Flexible and Freestanding Silicon/MXene Composite Papers for High-Performance Lithium-Ion Batteries

2D/3D hierarchical Zinc@Ti3C2Tx-MXene composite-coated copper foil as dendrite-free lithium host for stable lithium metal batteries

Lithium metal, with its ultrahigh theoretical capacity (3860 mAh g-1) and the lowest redox potential among metallic anodes (-3.04 V vs. SHE), is regarded as the ultimate anode for next-generation high-energy-density batteries. However, rampant dendrite growth and unstable solid electrolyte interphase (SEI) formation critically hinder its practical adoption. Herein, we design a hierarchical 2D/3D Zinc@MXene (Zn@M) composite-coated Cu current collector to stabilize lithium metal anodes. The MXene nanosheets (Ti3C2Tx) function as lithium-philic conductive channels to homogenize Li+ flux, while micrometer-sized Zn particles construct a porous scaffold that mitigates MXene restacking and provides preferential nucleation sites for lithium deposition. Benefiting from the strong interfacial bonding between MXene and Zn, the composite forms a robust dual-phase architecture with enhanced mechanical integrity and ion/electron transport efficiency. This synergy enables dendrite-free Li plating/stripping, as evidenced by the Li||Zn@M half-cell achieving a high average coulombic efficiency of 97.6 % over 450 cycles (1 mA cm-2/1 mAh cm-2) and symmetrical cells sustaining stable operation for 3300 h (1 mA cm-2/1 mAh cm-2). Remarkably, when paired with a high-loading LiFePO4 cathode (12.7 mg cm-2) in anode-free configuration, the Zn@M/Cu current collector demonstrates exceptional full-cell cyclability with 70 % capacity retention after 50 cycles. This work provides a universal interface engineering strategy for realizing dendrite-suppressive lithium hosts, paving the way toward practical high-energy lithium-metal batteries.

Suppression Strategies for Si Anode Volume Expansion in Li-Ion Batteries Based on Structure Design and Modification: A Review

Silicon anodes have received increasing attention due to their exceptionally high theoretical capacity in lithium-ion batteries (LIBs). However, the defect of anode volume expansion caused by solid-electrolyte interphase (SEI) crushing limits the cycle life seriously. To overcome the obstacle, one must understand the mechanism behind anode volume expansion prior to exploring the suppression strategies. In this review, the recent advances in Si-based anode modification and structural design are categorized comprehensively, the scaled-up framework structures are deeply discussed, and the impacts of various composite structures on cycling performance and Coulombic efficiency are emphasized, particularly the synergistic effects of carbon/MXene assembled with silicon. Some reliable strategies for anode volume expansion restriction have been proposed. The porous structure of monocrystalline silicon spheres reconstructed by alloy sintering can restrain volume expansion effectively due to the reshaped uniform internal stress field. The inner-stress offset induced by Si anode expansion and two-dimensional material layer collapse can provide a perfect inhibition effect on SEI fragmentation when monocrystalline silicon spheres are assembled with graphene or MXene. Moreover, how special nanoshape structures provide anode stability after long cycles are summarized. This current review will be beneficial to facilitate the exploration of strategies for suppression of Si-based anode volume expansion and to pave an avenue for extensive application of Si-based LIBs in the future.

Advances and future perspectives on silicon-based anodes for lithium-ion batteries

Silicon (Si)-based anode has emerged as the most promising anode material for next-generation lithium-ion batteries (LIBs) due to its high specific capacity, suitable operating potential and abundant natural reserves. Nevertheless, the drastic volume effect of Si particles during lithiation/delithiation leads to particle pulverization, electrode structure collapse, and solid electrolyte interfacial (SEI) film instability, which results in a rapid reversible capacity degradation of Si-based anodes. It is essential to deeply analyze the failure mechanism of silicon-based electrodes and explore suitable improvement methods to achieve higher capacity retention. Herein, we systematically summarize the improvement strategies for Si-based anodes, including regulating material particle size, optimizing structure and composition, and exploring new binders, along with their enhancement mechanisms. In addition, the preparation of high-performance Si-based electrodes based on newly developed 3D printing technology in recent years is discussed. Lastly, several possible directions and emerging challenges for Si anode are presented to facilitate further improvement in practical applications. Overall, this review is expected to provide basic understanding and insights into the practical application of Si-based materials in next-generation LIBs negative electrodes.

Fundamentals, Advances and Perspectives in Designing Eutectic Electrolytes for Zinc-Ion Secondary Batteries

Zinc-ion secondary batteries have been competitive candidates since the "post-lithium-ion" era for grid-scale energy storage, owing to their plausible security, high theoretical capacity, plentiful resources, and environment friendliness. However, many encumbrances like notorious parasitic reactions and Zn dendrite growth hinder the development of zinc-ion secondary batteries remarkably. Faced with these challenges, eutectic electrolytes have aroused notable attention by virtue of feasible synthesis and high tunability. This review discusses the definition and advanced functionalities of eutectic electrolytes in detail and divides them into nonaqueous, aqueous, and solid-state eutectic electrolytes with regard to the state and component of electrolytes. In particular, the corresponding chemistry concerning solvation structure regulation, electric double layer (EDL) structure, solid-electrolyte interface (SEI) and charge/ion transport mechanism is systematically elucidated for a deeper understanding of eutectic electrolytes. Moreover, the remaining limitations and further development of eutectic electrolytes are discussed for advanced electrolyte design and extended applications.

Commercial SiO Encapsulated in Hybrid Bilayer Conductive Skeleton as Stable Anode Coupling Chemical Prelithiation for Lithium-Ion Batteries

Although Silicon monoxide (SiO) is regarded as the most promising next-generation anode material, the large volume expansion, poor conductivity, and low initial Coulombic efficiency (ICE) severely hamper its commercialization application. Designing a multilayer conductive skeleton combined with advanced prelithiation technology is considered an effective approach to address these problems. Herein, a reliable strategy is proposed that utilizes MXene and carbon nanotube (CNT) as dual-conductive skeletons to encapsulate SiO through simple electrostatic interaction for high-performance anodes in LIBs, while also performing chemical prelithiation. Various characterizations and electrochemical measurements indicate that both MXene and CNT, as conductive networks and buffer interfaces, synergistically enhance the electron transport and lithium storage properties of the electrode. Moreover, the chemical prelithiation process effectively improves the ICE and cycling stability. Consequently, the prepared SiO@MXene@CNT anode delivers a high capacity of 1032 mAh g-1 after 200 cycles at 200 mA g-1 and an ultrahigh capacity retention rate of 89.5% beyond 1000 cycles at 1000 mA g-1. More importantly, the ICE of the SiO@MXene@CNT anode increases from 65.1% to 92.3% after chemical prelithiation. The work opens a new avenue for significantly improving the lithium storage performance of SiO-based anodes and is expected to promote their commercialization progress.

Tuning MXene Pathways via Silver Nanoparticle Size Variations for Anode-Free Battery Applications

MXenes, a class of two-dimensional titanium carbide materials, have emerged as promising materials for film-based applications due to their exceptional properties. However, their densely layered structures hinder ion diffusion, metal-ion mobility, and nanoscale particle transfer, limiting their potential in energy-related applications. Expanding and controlling interlayer spacing is essential for overcoming these limitations and optimizing MXene performance. In this study, silver nanoparticles (AgNPs) measuring 20 and 55 nm in size were incorporated into dense MXene structures to control and expand their pathways. X-ray diffraction confirmed the lamellar structure of pristine MXene, and detailed analyses using electron microscopy and small-angle neutron scattering demonstrated that the size and concentration of AgNPs directly influenced pathway expansion. The interlayer spacing increased significantly, with widths growing from 2.4 nm to ∼25 nm as the AgNP parameters varied. Electrochemical impedance spectroscopy results revealed that the densely packed structure of pristine MXene was unsuitable for use as an anode-current collector coating in batteries. In contrast, the MXene/AgNP composite demonstrated effective functionality due to the expanded pathways, which improved ion transfer and conductivity. These findings underscore the importance of pathway engineering and the use of additive insertion methods in advancing MXene-based materials for energy storage and other functional applications.

A brief review on the progress of MXene-based catalysts for electro- and photochemical water splitting for hydrogen generation

The development and generation of affordable and highly efficient energy, particularly hydrogen, are one of the best approaches to address the challenges posed by the depletion of non-renewable energy sources. Hydrogen energy, as a green and ecosystem-friendly source with zero carbon emission, can be generated through various methods, including water splitting (HER/OER) via either photo- or electrocatalytic reactions. To implement these reactions effectively in practical applications, it is highly desirable to develop extremely efficient and cost-effective catalytic materials that are comparable to contemporary catalysts. MXenes, a family of newly discovered 2D transition metal carbides, nitrides, or carbonitrides with surface termination groups, such as -OH, -O, and -F, have emerged as promising materials and substrates for photo- and electrocatalytic applications due to their unique characteristics. These include excellent conductivity provided by the transition metals, hydrophilic nature imparted by the surface termination groups, high mechanical stability, fast electronic transmission and extremely high surface area-to-volume ratios. In this review, we provide detailed insights into the synthesis, properties, and catalytic applications of MXenes. We systematically outline the photo- and electrocatalytic water splitting reactions carried out by various MXene-based heterostructures, supported by experimental data. A thorough deliberation on the structure-activity associations of reported catalysts and a basic understanding of the electrocatalytic applications of MXenes are also included. Furthermore, we offer an insight into the upcoming tasks, challenges, prospects and new research strategies for MXenes in water splitting applications. A noteworthy recognition of the design and optimization of extremely efficient MXene-based catalysts in water splitting applications is therefore offered in this review.

Recent progress in Si/Ti3C2Tx MXene anode materials for lithium-ion batteries

Cardiovascular diseases (CVDs) are a major global health issue, causing significant morbidity and mortality worldwide. Early diagnosis and continuous monitoring of physiological signals are crucial for managing cardiovascular diseases, necessitating the development of lightweight and cost-effective wearable devices. These devices should incorporate portable energy storage systems, such as lithium-ion batteries (LIBs). To enhance the durability and consistency of the monitoring systems, there is a need to develop LIBs with high energy density. Silicon-based materials hold great promise for future LIBs anodes due to their high theoretical capacity and cost-efficiency. Despite their potential, silicon-based materials encounter challenges like substantial volume fluctuations and sluggish kinetics. Transition metal carbide, MXene, features a two-dimensional structure, offering advantages in silicon-based anode materials. This review initially presents the potential of silicon-based anodes and then addresses their challenges. Subsequently, the advantages of MXene are systematically reviewed, including unique structure, abundant surface functional groups, excellent electrical conductivity, and excellent ion transport performance. Next, the detailed discussion covers recent advancements in Si/Ti3C2Tx MXene anode materials for LIBs, with a focus on their synthesis methods. Finally, the challenges and future perspectives of synthesizing Si/Ti3C2Tx nanocomposites are examined, aiming to provide a foundational resource for designing advanced materials for high-energy LIBs.

Low-cost silicon cutting waste reused as a high-power-density silicon-based anode

With the rapid development of electric vehicle technology, commercial graphite anodes (theoretical capacity of 372 mA h g-1) of lithium-ion batteries cannot meet the needs for high power density. Silicon has high theoretical capacity (4200 mA h g-1), low working voltage (about 0.4 V vs. Li/Li+), rich resources and environmental friendly nature; hence, it is regarded as a potential negative electrode material. During repeated charging and discharging, silicon particles continuously pulverize, which leads to the volume expansion of electrode materials (up to 400%) and a decrease in conductivity. In this study, high-purity nano-silicon was prepared via a calcination-ball milling-pickling process with low-cost silicon cutting waste (SiCW) as a raw material to meet the needs of lithium-ion batteries for high-purity and nano-scale silicon-based anodes. At the same time, silicon@graphite nanocomposites with different mass ratios were prepared via a low-cost industrialized ball-milling process. The easy intercalation and softness of the graphite layer structure realized the coating and joining of nano-silicon, which improved the conductivity of nano-silicon and restrained the rapid degradation of cycling performance caused by the expansion and pulverization of the silicon-based anode. Adopting low-cost raw materials and industrialization-based preparation processes can effectively control the production cost of silicon-based anode materials and lay a solid foundation for their practicality.

Empowering Green Energy Storage Systems with MXene for a Sustainable Future

Green energy storage systems play a vital role in enabling a sustainable future by facilitating the efficient integration and utilization of renewable energy sources. The main problems related to two-dimensional (2D) materials are their difficult synthesis process, high cost, and bulk production, which hamper their performance. In recent years, MXenes have emerged as highly promising materials for enhancing the performance of energy storage devices due to their unique properties, including their high surface area, excellent electrical and thermal conductivity, and exceptional chemical stability. This paper presents a comprehensive scientific approach that explores the potential of MXenes for empowering green energy storage systems. Which indicates the novelty of the article. The paper reviews the latest advances in MXene synthesis techniques. Furthermore, investigates the application of MXenes in various energy storage technologies, such as lithium-ion batteries, supercapacitors, and emerging energy storage devices. The utilization of MXenes as electrodes in flexible and transparent energy storage devices is also discussed. Moreover, the paper highlights the potential of MXenes in addressing key challenges in energy storage, including enhancing energy storage capacity, improving cycling stability, and promoting fast charging and discharging rates. Additionally, industrial application and cost estimation of MXenes are explored. As the output of the work, we analyzed that HF and modified acid (LiF and HCl) are the established methods for synthesis. Due to high electrical conductivity, MXene materials are showing extraordinary results in energy storage and related applications. Making a composite hydrothermal method is one of the established methods. This scientific paper underscores the significant contributions of MXenes in advancing green energy storage systems, paving the way for a sustainable future driven by renewable energy sources. To facilitate the research, this article includes technical challenges and future recommendations for further research gaps in the topic.

Preparation of WSi@SiOx/Ti3C2 from photovoltaic silicon waste as high-performance anode materials for lithium-ion batteries

Silicon anodes hold promise for future lithium-ion batteries (LIBs) due to their high capacity, but they face challenges such as severe volume expansion and low electrical conductivity. In this study, we present a straightforward and scalable electrostatic self-assembly method to fabricate WSi@SiOx/Ti3C2 composites for LIBs. Silicon nanosheets and the ultra-thin oxide layer SiOx serve as sufficient buffers against volume changes, while the layered MXene enhances the electrical conductivity of the composite and promoted Li+/e- transport. Additionally, cationic surfactant-treated Ti3C2 provides more active sites for WSi@SiOx attachment and acts as an intercalating agent, enabling WSi@SiOx to enter the interlayer spaces of Ti3C2. The WSi@SiOx/Ti3C2 electrodes significantly improved electrochemical performance, achieving a capacity of 1,130 mAh g-1 after 800 charge/discharge cycles at 500 mA g-1. This study not only presents a straightforward pathway for high-value utilization of silicon waste but also offers a feasible route for preparing high-performance and cost-effective silicon-based LIBs.

Design of dual carbon encapsulated porous micron silicon composite with compact surface for enhanced reaction kinetics of lithium-ion battery anodes

Developing high-performance composites with fast charging and superior cycle life is paramount for lithium-ion batteries (LIBs). Herein, we synthesized a double-shell carbon-coated porous structure composite with a compact surface (P-Si@rGO@C) using low-cost commercial micron-sized silicon (Si) instead of nanoscale silicon. Results reveal that the unique P-Si@rGO@C features high adaptability to volume expansion, accelerates electron/ion transmission rate, and forms a stable solid electrolyte interphase (SEI) film. This phenomenon arises from the synergistic effect of abundant internal voids and an external double-layer carbon shell with a dense surface. Specifically, the P-Si@rGO@C anode exhibits a high initial coulombic efficiency (ICE) (88.0 %), impressive rate-capability (612.1 mAh/g at 2C), and exceptional long-term cyclability (972.2 mAh/g over 500 cycles at 0.5C). Further kinetic studies elucidate the diffusion-capacitance hybrid energy storage mechanism and reveal an improved Li+ diffusion coefficient (from 3.47 × 10-11 to 2.85 × 10-9 cm2 s-1). Ex-situ characterization confirms the crystal phase change of micron-sized Si and the formation of a stable LiF-rich SEI. Theoretical calculations support these findings by demonstrating an enhancement in the adsorption ability of Si to Li+ (from -0.89 to -0.97 eV) and a reduction in the energy migration barrier (from 0.35 to 0.18 eV). Additionally, practical LixSi powder is shown to increase the ICE of full cells from 67.4 % to 87.9 %. Furthermore, a pouch cell utilizing the prelithiated P-Si@rGO@C anode paired with LiNi1/3Co1/3Mn1/3O2 (NCM111) cathode delivers a high initial reversible capacity of 7.2 mAh and 76.8 % capacity retention after 100 cycles. This work provides insights into the application of commercial silicon-aluminum alloy powder in the anode of high-energy LIBs.

Innovative Solutions for High-Performance Silicon Anodes in Lithium-Ion Batteries: Overcoming Challenges and Real-World Applications

Silicon (Si) has emerged as a potent anode material for lithium-ion batteries (LIBs), but faces challenges like low electrical conductivity and significant volume changes during lithiation/delithiation, leading to material pulverization and capacity degradation. Recent research on nanostructured Si aims to mitigate volume expansion and enhance electrochemical performance, yet still grapples with issues like pulverization, unstable solid electrolyte interface (SEI) growth, and interparticle resistance. This review delves into innovative strategies for optimizing Si anodes' electrochemical performance via structural engineering, focusing on the synthesis of Si/C composites, engineering multidimensional nanostructures, and applying non-carbonaceous coatings. Forming a stable SEI is vital to prevent electrolyte decomposition and enhance Li+ transport, thereby stabilizing the Si anode interface and boosting cycling Coulombic efficiency. We also examine groundbreaking advancements such as self-healing polymers and advanced prelithiation methods to improve initial Coulombic efficiency and combat capacity loss. Our review uniquely provides a detailed examination of these strategies in real-world applications, moving beyond theoretical discussions. It offers a critical analysis of these approaches in terms of performance enhancement, scalability, and commercial feasibility. In conclusion, this review presents a comprehensive view and a forward-looking perspective on designing robust, high-performance Si-based anodes the next generation of LIBs.

MXene as Promising Anode Material for High-Performance Lithium-Ion Batteries: A Comprehensive Review

Broad adoption has already been started of MXene materials in various energy storage technologies, such as super-capacitors and batteries, due to the increasing versatility of the preparation methods, as well as the ongoing discovery of new members. The essential requirements for an excellent anode material for lithium-ion batteries (LIBs) are high safety, minimal volume expansion during the lithiation/de-lithiation process, high cyclic stability, and high Li+ storage capability. However, most of the anode materials for LIBs, such as graphite, SnO2, Si, Al, and Li4Ti5O12, have at least one issue. Hence, creating novel anode materials continues to be difficult. To date, a few MXenes have been investigated experimentally as anodes of LIBs due to their distinct active voltage windows, large power capabilities, and longer cyclic life. The objective of this review paper is to provide an overview of the synthesis and characterization characteristics of the MXenes as anode materials of LIBs, including their discharge/charge capacity, rate performance, and cycle ability. In addition, a summary of the potential outlook for developments of these materials as anodes is provided.

Multiscale Structural Design of 2D Nanomaterials-based Flexible Electrodes for Wearable Energy Storage Applications

2D nanomaterials play a critical role in realizing high-performance flexible electrodes for wearable energy storge devices, owing to their merits of large surface area, high conductivity and high strength. The electrode is a complex system and the performance is determined by multiple and interrelated factors including the intrinsic properties of materials and the structures at different scales from macroscale to atomic scale. Multiscale design strategies have been developed to engineer the structures to exploit full potential and mitigate drawbacks of 2D materials. Analyzing the design strategies and understanding the working mechanisms are essential to facilitate the integration and harvest the synergistic effects. This review summarizes the multiscale design strategies from macroscale down to micro/nano-scale structures and atomic-scale structures for developing 2D nanomaterials-based flexible electrodes. It starts with brief introduction of 2D nanomaterials, followed by analysis of structural design strategies at different scales focusing on the elucidation of structure-property relationship, and ends with the presentation of challenges and future prospects. This review highlights the importance of integrating multiscale design strategies. Finding from this review may deepen the understanding of electrode performance and provide valuable guidelines for designing 2D nanomaterials-based flexible electrodes.

Synergistic Charge Storage Enhancement in Supercapacitors via Ti3C2Tx MXene and CoMoO4 Nanoparticles

MXene has emerged as a highly promising two-dimensional (2D) layered material with inherent advantages as an electrode material, such as a high electrical conductivity and spacious layer distances conducive to efficient ion transport. Despite these merits, the practical implementation faces challenges due to MXene's low theoretical capacitance and issues related to restacking. In order to overcome these limitations, we undertook a strategic approach by integrating Ti3C2Tx MXene with cobalt molybdate (CoMoO4) nanoparticles. The CoMoO4 nanoparticles bring to the table rich redox activity, high theoretical capacitance, and exceptional catalytic properties. Employing a facile hydrothermal method, we synthesized CoMoO4/Ti3C2Tx heterostructures, leveraging urea as a size-controlling agent for the CoMoO4 precursors. This innovative heterostructure design utilizes Ti3C2Tx MXene as a spacer, effectively mitigating excessive agglomeration, while CoMoO4 contributes its enhanced redox reaction capabilities. The resulting CoMoO4/Ti3C2Tx MXene hybrid material exhibited 698 F g-1 at a scan rate of 5 mV s-1, surpassing that of the individual pristine Ti3C2Tx MXene (1.7 F g-1) and CoMoO4 materials (501 F g-1). This integration presents a promising avenue for optimizing MXene-based electrode materials, addressing challenges and unlocking their full potential in various applications.

Intercalation of C60 into MXene Multilayers: A Promising Approach for Enhancing the Electrochemical Properties of Electrode Materials for High-Performance Energy Storage Applications

In this study, we report on the enhancement of the electrochemical properties of MXene by intercalating C60 nanoparticles between its layers. The aim was to increase the interlayer spacing of MXene, which has a direct effect on capacitance by allowing the electrolyte flow in the electrode. To achieve this, various concentrations of Ti3SiC2 (known as MXene) and C60 nanocomposites were prepared through a hydrothermal process under optimal conditions. The resulting composites were characterized by using X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, Raman spectroscopy, and cyclic voltammetry. Electrodes were fabricated using different concentrations of MXene and C60 nanocomposites, and current-voltage (I-V) measurements were performed at various scan rates to analyze the capacitance of pseudo supercapacitors. The results showed the highest capacitance of 348 F g1- for the nanocomposite with a composition of 90% MXene and 10% C60. We introduce MXene-C60 composites as promising electrode materials for supercapacitors and highlight their unique properties. Our work provides a new approach to designing high-performance electrode materials for supercapacitors, which can have significant implications for the development of efficient energy storage systems.

MXene-Based Current Collectors for Advanced Rechargeable Batteries

As an indispensable component of rechargeable batteries, the current collector plays a crucial role in supporting the electrode materials and collecting the accumulated electrical energy. However, some key issues, like uneven resources, high weight percentage, electrolytic corrosion, and high-voltage instability, cannot meet the growing need for rechargeable batteries. In recent years, MXene-based current collectors have achieved considerable achievements due to its unique structure, large surface area, and high conductivity. The related research has increased significantly. Nonetheless, a comprehensive review of this area is seldom. Herein the applications and progress of MXene in current collector are systematically summarized and discussed. Meanwhile, some challenges and future directions are presented.

Unleashing the Potential of MXene-Based Flexible Materials for High-Performance Energy Storage Devices

Since the initial discovery of Ti3 C2 a decade ago, there has been a significant surge of interest in 2D MXenes and MXene-based composites. This can be attributed to the remarkable intrinsic properties exhibited by MXenes, including metallic conductivity, abundant functional groups, unique layered microstructure, and the ability to control interlayer spacing. These properties contribute to the exceptional electrical and mechanical performance of MXenes, rendering them highly suitable for implementation as candidate materials in flexible and wearable energy storage devices. Recently, a substantial number of novel research has been dedicated to exploring MXene-based flexible materials with diverse functionalities and specifically designed structures, aiming to enhance the efficiency of energy storage systems. In this review, a comprehensive overview of the synthesis and fabrication strategies employed in the development of these diverse MXene-based materials is provided. Furthermore, an in-depth analysis of the energy storage applications exhibited by these innovative flexible materials, encompassing supercapacitors, Li-ion batteries, Li-S batteries, and other potential avenues, is conducted. In addition to presenting the current state of the field, the challenges encountered in the implementation of MXene-based flexible materials are also highlighted and insights are provided into future research directions and prospects.

Chemistry Aspects and Designing Strategies of Flexible Materials for High-Performance Flexible Lithium-Ion Batteries

In recent years, flexible and wearable electronics such as smart cards, smart fabrics, bio-sensors, soft robotics, and internet-linked electronics have impacted our lives. In order to meet the requirements of more flexible and adaptable paradigm shifts, wearable products may need to be seamlessly integrated. A great deal of effort has been made in the last two decades to develop flexible lithium-ion batteries (FLIBs). The selection of suitable flexible materials is important for the development of flexible electrolytes self-supported and supported electrodes. This review is focused on the critical discussion of the factors that evaluate the flexibility of the materials and their potential path toward achieving the FLIBs. Following this analysis, we present how to evaluate the flexibility of the battery materials and FLIBs. We describe the chemistry of carbon-based materials, covalent-organic frameworks (COFs), metal-organic frameworks (MOFs), and MXene-based materials and their flexible cell design that represented excellent electrochemical performances during bending. Furthermore, the application of state-of-the-art solid polymer and solid electrolytes to accelerate the development of FLIBs is introduced. Analyzing the contributions and developments of different countries has also been highlighted in the past decade. In addition, the prospects and potential of flexible materials and their engineering are also discussed, providing the roadmap for further developments in this fast-evolving field of FLIB research.

Versatile Protein and Its Subunit Biomolecules for Advanced Rechargeable Batteries

Rechargeable batteries are of great significance for alleviating the growing energy crisis by providing efficient and sustainable energy storage solutions. However, the multiple issues associated with the diverse components in a battery system as well as the interphase problems greatly hinder their applications. Proteins and their subunits, peptides, and amino acids, are versatile biomolecules. Functional groups in different amino acids endow these biomolecules with unique properties including self-assembly, ion-conducting, antioxidation, great affinity to exterior species, etc. Besides, protein and its subunit materials can not only work in solid forms but also in liquid forms when dissolved in solutions, making them more versatile to realize materials engineering via diverse approaches. In this review, it is aimed to offer a comprehensive understanding of the properties of proteins and their subunits, and research progress of using these versatile biomolecules to address the engineering issues of various rechargeable batteries, including alkali-ion batteries, lithium-sulfur batteries, metal-air batteries, and flow batteries. The state-of-the-art advances in electrode, electrolyte, separator, binder, catalyst, interphase modification, as well as recycling of rechargeable batteries are involved, and the impacts of biomolecules on electrochemical properties are particularly emphasized. Finally, perspectives on this interesting field are also provided.

Strategies for Advanced Supercapacitors Based on 2D Transition Metal Dichalcogenides: From Material Design to Device Setup

Recently, the development of new materials and devices has become the main research focus in the field of energy. Supercapacitors (SCs) have attracted significant attention due to their high power density, fast charge/discharge rate, and excellent cycling stability. With a lamellar structure, 2D transition metal dichalcogenides (2D TMDs) emerge as electrode materials for SCs. Although many 2D TMDs with excellent energy storage capability have been reported, further optimization of electrode materials and devices is still needed for competitive electrochemical performance. Previous reviews have focused on the performance of 2D TMDs as electrode materials in SCs, especially on their modification. Herein, the effects of element doping, morphology, structure and phase, composite, hybrid configuration, and electrolyte are emphatically discussed on the overall performance of 2D TMDs-based SCs from the perspective of device optimization. Finally, the opportunities and challenges of 2D TMDs-based SCs in the field are highlighted, and personal perspectives on methods and ideas for high-performance energy storage devices are provided.

2D MXenes polar catalysts for multi-renewable energy harvesting applications

The synchronous harvesting and conversion of multiple renewable energy sources for chemical fuel production and environmental remediation in a single system is a holy grail in sustainable energy technologies. However, it is challenging to develop advanced energy harvesters that satisfy different working mechanisms. Here, we theoretically and experimentally disclose the use of MXene materials as versatile catalysts for multi-energy utilization. Ti₃C₂T_X MXene shows remarkable catalytic performance for organic pollutant decomposition and H₂ production. It outperforms most reported catalysts under the stimulation of light, thermal, and mechanical energy. Moreover, the synergistic effects of piezo-thermal and piezo-photothermal catalysis further improve the performance when using Ti₃C₂T_X. A mechanistic study reveals that hydroxyl and superoxide radicals are produced on the Ti₃C₂T_X under diverse energy stimulation. Furthermore, similar multi-functionality is realized in Ti₂CT_X, V₂CT_X, and Nb₂CT_X MXene materials. This work is anticipated to open a new avenue for multisource renewable energy harvesting using MXene materials.

MXene-Based Nanocomposites for Piezoelectric and Triboelectric Energy Harvesting Applications

Due to its superior advantages in terms of electronegativity, metallic conductivity, mechanical flexibility, customizable surface chemistry, etc., 2D MXenes for nanogenerators have demonstrated significant progress. In order to push scientific design strategies for the practical application of nanogenerators from the viewpoints of the basic aspect and recent advancements, this systematic review covers the most recent developments of MXenes for nanogenerators in its first section. In the second section, the importance of renewable energy and an introduction to nanogenerators, major classifications, and their working principles are discussed. At the end of this section, various materials used for energy harvesting and frequent combos of MXene with other active materials are described in detail together with the essential framework of nanogenerators. In the third, fourth, and fifth sections, the materials used for nanogenerators, MXene synthesis along with its properties, and MXene nanocomposites with polymeric materials are discussed in detail with the recent progress and challenges for their use in nanogenerator applications. In the sixth section, a thorough discussion of the design strategies and internal improvement mechanisms of MXenes and the composite materials for nanogenerators with 3D printing technologies are presented. Finally, we summarize the key points discussed throughout this review and discuss some thoughts on potential approaches for nanocomposite materials based on MXenes that could be used in nanogenerators for better performance.

MXene: fundamentals to applications in electrochemical energy storage

A new, sizable family of 2D transition metal carbonitrides, carbides, and nitrides known as MXenes has attracted a lot of attention in recent years. This is because MXenes exhibit a variety of intriguing physical, chemical, mechanical, and electrochemical characteristics that are closely linked to the wide variety of their surface terminations and elemental compositions. Particularly, MXenes are readily converted into composites with materials including oxides, polymers, and CNTs, which makes it possible to modify their characteristics for a variety of uses. MXenes and MXene-based composites have demonstrated tremendous promise in environmental applications due to their excellent reducibility, conductivity, and biocompatibility, in addition to their well-known rise to prominence as electrode materials in the energy storage sector. The remarkable characteristics of 2D MXene, including high conductivity, high specific surface area, and enhanced hydrophilicity, account for the increasing prominence of its use in storage devices. In this review, we highlight the most recent developments in the use of MXenes and MXene-based composites for electrochemical energy storage while summarizing their synthesis and characteristics. Key attention is paid to applications in supercapacitors, batteries, and their flexible components. Future research challenges and perspectives are also described.

Metal Ion-Induced Porous MXene for All-Solid-State Flexible Supercapacitors

MXenes are normally used for energy storage applications. However, large nanosheets and restacking are detrimental to the ion diffusion and thus limit its rate capability. Here, a strategy to prepare flexible and porous MXene-M supercapacitor electrodes can simultaneously enlarge the interlayer spacing between layers and create holes in the layers. As a result, Ti₃C₂T_x-Mn presents an excellent lifespan, with still 248 F g^-1 after 100 000 cycles at a current density of 100 A g^-1. Moreover, Ti₃C₂T_x-Mn-based symmetric all-solid-state supercapacitor exhibits outstanding volumetric energy up to 52.4 mWh cm^-3 and retains 38.4 mWh cm^-3 at an ultrahigh volumetric power density of 55.3 W cm^-3. We believe this work provides an idea for the later regulation of MXene layer spacing and the design of porous structures, and can be widely used in the next-generation high-energy density and power density practical applications.

A Rising 2D Star: Novel MBenes with Excellent Performance in Energy Conversion and Storage

As a flourishing member of the two-dimensional (2D) nanomaterial family, MXenes have shown great potential in various research areas. In recent years, the continued growth of interest in MXene derivatives, 2D transition metal borides (MBenes), has contributed to the emergence of this 2D material as a latecomer. Due to the excellent electrical conductivity, mechanical properties and electrical properties, thus MBenes attract more researchers' interest. Extensive experimental and theoretical studies have shown that they have exciting energy conversion and electrochemical storage potential. However, a comprehensive and systematic review of MBenes applications has not been available so far. For this reason, we present a comprehensive summary of recent advances in MBenes research. We started by summarizing the latest fabrication routes and excellent properties of MBenes. The focus will then turn to their exciting potential for energy storage and conversion. Finally, a brief summary of the challenges and opportunities for MBenes in future practical applications is presented.

Towards Greener and More Sustainable Synthesis of MXenes: A Review

The unique properties of MXenes have been deemed to be of significant interest in various emerging applications. However, MXenes provide a major drawback involving environmentally harmful and toxic substances for its general fabrication in large-scale production and employing a high-temperature solid-state reaction followed by selective etching. Meanwhile, how MXenes are synthesized is essential in directing their end uses. Therefore, making strategic approaches to synthesize greener, safer, more sustainable, and more environmentally friendly MXenes is imperative to commercialize at a competitive price. With increasing reports of green synthesis that promote advanced technologies and non-toxic agents, it is critical to compile, summarize, and synthesize the latest development of the green-related technology of MXenes. We review the recent progress of greener, safer, and more sustainable MXene synthesis with a focus on the fundamental synthetic process, the mechanism, and the general advantages, and the emphasis on the MXene properties inherited from such green synthesis techniques. The emerging use of the so-called green MXenes in energy conversion and storage, environmental remediation, and biomedical applications is presented. Finally, the remaining challenges and prospects of greener MXene synthesis are discussed.

MXenes Thin Films: From Fabrication to Their Applications

Two-dimensional MXenes possessed exceptional physiochemical properties such as high electrical conductivity (20,000 Scm-1), flexibility, mechanical strength (570 MPa), and hydrophilic surface functionalities that have been widely explored for energy storage, sensing, and catalysis applications. Recently, the fabrication of MXenes thin films has attracted significant attention toward electronic devices and sensor applications. This review summarizes the exciting features of MXene thin film fabrication methods such as vacuum-assisted filtration (VAF), electrodeposition techniques, spin coating, spray coating, dip-coating methods, and other physical/chemical vapor deposition methods. Furthermore, a comparison between different methods available for synthesizing a variety of MXenes films was discussed in detail. This review further summarizes fundamental aspects and advances of MXenes thin films in solar cells, batteries, electromagnetic interference shielding, sensing, etc., to date. Finally, the challenges and opportunities in terms of future research, development, and applications of MXenes-based films are discussed. A comprehensive understanding of these competitive features and challenges shall provide guidelines and inspiration for further growth in MXenes-based functional thin films and contribute to the advances in MXenes technology.

Large areal capacity all-in-one lithium-ion battery based on boron-doped silicon/carbon hybrid anode material and cellulose framework

Si, featuring ultra-large theoretical specific capacity, is a very promising alternative to graphite for Li-ion batteries (LIBs). However, Si suffers from intrinsic low electrical conductivity and structural instability upon lithiation, thereby severely deteriorating its electrochemical performance. To address these issues, B-doping into Si, N-doped carbon coating layer, and carbon nanotube conductive network are combined in this work. The obtained Si/C hybrid anode material can be "grown" onto the Cu foil without using any binder and delivers large specific capacity (2328 mAh g^-1 at 0.2 A g^-1), great rate capability (1296.8 mAh g^-1 at 4 A g^-1), and good cyclability (76.7% capacity retention over 500 cycles). Besides, a cellulose separator derived from cotton is found to be superior to traditional polypropylene separator. By using cellulose as both the separator host and the mechanical skeleton of two electrodes, a flexible all-in-one paper-like LIB is assembled via a facile layer-by-layer filtration method. In this all-in-one LIB, all the components are integrated together with robust interfaces. This LIB is able to offer commercial-level areal capacity of 3.47 mAh cm^-2 (corresponding to 12.73 mWh cm^-2 and 318.3 mWh cm^-3) and good cycling stability even under bending. This study offers a new route for optimizing Si-based anode materials and constructing flexible energy storage devices with a large areal capacity.

Preparations and Applications of MXene–Metal Composites: A Review

MXene, an advanced family of 2D ceramic material resembling graphene, has had a considerable impact on the field of research because of its unique physiochemical properties. MXene has been synthesized by the selective etching of MAX via different techniques. However, with the passage of time, due to the need for further progress and improvement in MXene materials, ideas have turned toward composite fabrication, which has aided boosting the MXene composites regarding their properties and applications in various areas. Many review papers are published on MXene and their composites with polymer, carbon nanotube, graphene, other carbon, metal oxides and sulfides, etc., except metal composite, and such papers discuss these composites thoroughly. In this review article, we illustrate and explain the development of MXene-based metal composites. Furthermore, we highlight the synthesis techniques utilized for the preparation of MXene composites with metal. We briefly discuss the enhancement of properties of the composites and a wide range of applications as an electrode substance for energy storage devices, electrochemical cells, supercapacitors, and catalytic and anti-corrosive performance. Major obstacles in MXene and metal composite are mentioned and provide future recommendations. Together, they can overcome problems and enable MXene and composites on commercial-scale production.

Integrating Dually Encapsulated Si Architecture and Dense Structural Engineering for Ultrahigh Volumetric and Areal Capacity of Lithium Storage

High-theoretical-capacity silicon anodes hold promise in lithium-ion batteries (LIBs). Nevertheless, their huge volume expansion (∼300%) and poor conductivity show the need for the simultaneous introduction of low-density conductive carbon and nanosized Si to conquer the above issues, yet they result in low volumetric performance. Herein, we develop an integration strategy of a dually encapsulated Si structure and dense structural engineering to fabricate a three-dimensional (3D) highly dense Ti₃C₂T_x MXene and graphene dual-encapsulated Si monolith architecture (HD-Si@Ti₃C₂T_x@G). Because of its high density (1.6 g cm^-3), high conductivity (151 S m^-1), and 3D dense dual-encapsulated Si architecture, the resultant HD-Si@Ti₃C₂T_x@G monolith anode displays an ultrahigh volumetric capacity of 5206 mAh cm^-3 (gravimetric capacity: 2892 mAh g^-1) at 0.1 A g^-1 and a superior long lifespan of 800 cycles at 1.0 A g^-1. Notably, the thick and dense monolithic anode presents a large areal capacity of 17.9 mAh cm^-2. In-situ TEM and ex-situ SEM techniques, and systematic kinetics and structural stability analysis during cycling demonstrate that such superior volumetric and areal performances stem from its dual-encapsulated Si architecture by the 3D conductive and elastic networks of MXene and graphene, which can provide fast electron and ion transfer, effective volume buffer, and good electrolyte permeability even with a thick electrode, whereas the dense structure results in a large volumetric performance. This work offers a simple and feasible strategy to greatly improve the volumetric and areal capacity of alloy-based anodes for large-scale applications via integrating a dual-encapsulated strategy and dense-structure engineering.

One-Step, Vacuum-Assisted Construction of Micrometer-Sized Nanoporous Silicon Confined by Uniform Two-Dimensional N-Doped Carbon toward Advanced Li Ion and MXene-Based Li Metal Batteries

With the advantages of a high theoretical capacity, proper working voltage, and abundant reserves, silicon (Si) is regarded as a promising anode for lithium-ion batteries. However, huge volume expansion and low electronic conductivity impede the commercialization of Si anodes. We devised a one-step, vacuum-assisted reactive carbon coating technique to controllably produce micrometer-sized nanoporous silicon confined by homogeneous N-doped carbon nanosheet frameworks (NPSi@NCNFs), achieved by the solid state reaction of a commercial bulk precursor and the subsequent evaporation of byproducts. The graphitization degree, C and N contents of the carbon shell, as well as the porosity of Si can be regulated by adjusting the synthetic conditions. A rational structure can mitigate volume expansion to maintain structural integrity, enhance electronic conductivity to facilitate charge transport, and serve as a protected layer to stabilize the solid electrolyte interphase. The NPSi@NCNF anode enables a stable cycling performance with 95.68% capacity retention for 4000 cycles at 5 A g^-1. Furthermore, a flexible 2D/3D architecture is designed by conjugating NPSi@NCNFs with MXene. Lithiophilic NPSi@NCNFs homogenize Li nucleation and growth, evidenced by structural evolutions of MXene@NPSi@NCNF deposited Li. The application potential of NPSi@NCNFs and MXene@NPSi@NCNFs is estimated via assembling full cells with LiNi_0.8Co_0.1Mn_0.1O₂ and LiNi_0.5Mn_1.5O₄ cathodes. This work offers a method for the rational design of alloy-based materials for advanced energy storage.

Flexible Ti3C2Tx/Nanocellulose Hybrid Film as a Stable Zn-free Anode for Aqueous Hybrid Zn-Li Batteries

Aqueous zinc-based batteries are a very promising technology in the post-lithium era. However, excess zinc metals are often used, which results in not only making a waste but also lowering the actual energy density. Herein, a Ti₃C₂T_x/nanocellulose (derived from soybean stalks) hybrid film is prepared by a facile solution casting method and employed as the zinc-free anode for aqueous hybrid Zn-Li batteries. Benefiting from the ultra-low diameter and rich hydroxyl groups of nanocellulose, the hybrid film exhibits better mechanical properties, superior electrolyte wettability, and more importantly, significantly improved zinc plating/stripping reversibility compared to the pure Ti₃C₂T_x film. The hybrid film also dramatically overwhelms the stainless steel as the electrode for reversible zinc deposition. Further analysis shows that the hybrid film can lower the zinc deposition overpotential and promote the desolvation process of hydrated Zn²⁺ ions. In addition, it is found that hexagonal Zn thin flakes are horizontally deposited onto the hybrid film owing to the low lattice mismatch between the Ti₃C₂T_x surface and the (002) facet of Zn. Consequently, zinc dendritic growth and accompanied harmful side reactions can be considerably inhibited by the hybrid film, and the assembled Zn-Li hybrid batteries exhibit excellent electrochemical performances. This work might inspire future work on zinc-based batteries.

Conductive polymer doped two-dimensional MXene materials: opening the channel of magnesium ion transport

MXene has a series of advantages, such as high specific surface and conductivity, abundant surface functional groups, and effectively accelerating the electron conduction of electrochemically active sites. It is worth noting that due to the van der Waals force between MXene layers, the layers attract each other and the layer spacing becomes smaller, which cannot give full scope to the performance of MXene. Therefore, we introduce a conductive polymer PANI. The purpose of introducing acidified PANI to construct PANI/Ti₃C₂ composites is to make full use of the conductive framework of Ti₃C₂, the abundant functional groups on the surface, and the synergistic effect between the composites, to alleviate the stacking of Ti₃C₂ layers by occupying the active sites on the surface of Ti₃C₂ with PANI. At the same time, the proportion of PANI is changed to 40% of Ti₃C₂, and the composite when used as the cathode of magnesium ion batteries shows a mass-specific capacity of 132.2 mA h g⁻¹ and a series of excellent electrochemical properties at 50 mA g⁻¹ current. This provides a new design idea for the subsequent development of high-performance magnesium storage cathode materials.

A simple preparation method is used to obtain two-dimensional MXene material doped with a conductive polymer, which is used as cathode material of magnesium ion batteries to open the transmission channel of magnesium ions.

Lithium Storage Mechanism and Application of Micron-Sized Lattice-Reversible Binary Intermetallic Compounds as High-Performance Flexible Lithium-Ion Battery Anodes

A strategy of lattice-reversible binary intermetallic compounds of metallic elements is proposed for applications in flexible lithium-ion battery (LIB) anode with high capacity and cycling stability. First, the use of metallic elements can ensure excellent electronic conductivity and high capacity of the active anode substance. Second, binary intermetallic compounds possess a larger initial lattice volume than metallic monomers, so that the problem of volume expansion can be alleviated. Finally, the design of binary intermetallic compounds with lattice reversibility further improves the cycle stability. In this work, the feasibility of this strategy is verified using an indium antimonide (InSb) system. The volumetric expansion and lithium storage mechanism of InSb are investigated by in situ Raman characterization and theoretical calculations. The active material utilization is significantly improved and the growth of In whiskers is inhibited in the micron-sized ball-milled and carbon coated InSb (bInSb@C) anode, which exhibits a reversible capacity of 733.8 mAh g^-1 at 0.2 C, and provides a capacity of 411.5 mAh g^-1 after 200 cycles at 3 C with an average Coulombic efficiency of 99.95%. This strategy is validated in pouch cells, illustrating the great potential of lattice-reversible binary intermetallic compounds for use as commercial flexible LIB anodes.

Rational design of Ti3C2Cl2 MXenes nanodots-interspersed MXene@NiAl-layered double hydroxides for enhanced pseudocapacitor storage

Although electrodes based on two dimensional hybrids with interstratification-assemble have been widely studied for supercapacitors, the performance enhancement still remains challenge mainly due to the random dispersion of surface passivated two dimensional nanosheets. Herein, a new covalent surface functionalization of MXene-based Ti₃C₂Cl₂ nanodots-interspersed MXene@NiAl-layered double hydroxides (QD-Ti₃C₂Cl₂@NiAl-LDHs) hybrid electrode with superior pseudocapacitor storage performance has been elaborately designed by electrostatic-assembled. As a result, the QD-Ti₃C₂Cl₂@NiAl-LDHs electrode exhibits a super specific capacitance of 2010.8F g^-1 at 1.0 A g^-1 and high energy density of 100.5 Wh kg^-1 at a power density of 299.8 W kg^-1. In addition, 94.1% capacitance retention is achieved after cycling for 10,000 cycles at 1.0 A g^-1, outperforming previously reported of two dimensional hybrids electrode for supercapacitor. Furthermore, density functional theory (DFT) calculations show that the superior pseudocapacitor storage performance of the QD-Ti₃C₂Cl₂@NiAl-LDHs may be attributed to the creation of numerous electrochemical active sites and the enhancement of electrical conductivity by the QD-Ti₃C₂Cl₂ MXene. This work provides new strategy for developing excellent pseudocapacitor supercapacitor based on two dimensional hybrid electrode.

Crosslinking Nanoarchitectonics of Nitrogen-doped Carbon/MoS2 Nanosheets/Ti3 C2 Tx MXene Hybrids for Highly Reversible Sodium Storage

Although it is a promising sodium storage material due to its excellent electrochemical activity, small bandgap, and large interlayer spacing, layered molybdenum disulfide (MoS₂ ) suffers from poor rate capability and degraded cycling life, resulting from its serious aggregation upon preparation, sluggish reaction kinetics, and structure expansion during cycling. To address these issues, a polyethyleneimine (PEI)-assisted fabrication approach was developed for the rational synthesis of an interconnected framework with nitrogen-doped carbon-confined MoS₂ nanosheets/Ti₃ C₂ T_x MXene (MoS₂ /Ti₃ C₂ T_x @NC), where the PEI could guide the uniform growth of MoS₂ on Ti₃ C₂ T_x and the self-generated NC simultaneously enhanced its synergistic coupling with MoS₂ /Ti₃ C₂ T_x , thus contributing to the improvement of charge transfer, diffusion kinetics, and structural integrity of the hybrid electrode. Consequently, the desired MoS₂ /Ti₃ C₂ T_x @NC delivered impressive sodium storage performance, demonstrating high reversible capacities of 397.3 and 206.8 mAh g^-1 at 0.1 A g^-1 after 100 cycles and 0.5 A g^-1 after 500 cycles, respectively. Moreover, electrochemical kinetics analysis and charge storage mechanism manifested that high capacitive contribution, facilitated Na⁺ transport pathways, and synergistic electronic coupling between MoS₂ /Ti₃ C₂ T_x and NC contributed to the superior sodium storage performance.

Metal-Organic-Framework- and MXene-Based Taste Sensors and Glucose Detection

Taste sensors can identify various tastes, including saltiness, bitterness, sweetness, sourness, and umami, and have been useful in the food and beverage industry. Metal-organic frameworks (MOFs) and MXenes have recently received considerable attention for the fabrication of high-performance biosensors owing to their large surface area, high ion transfer ability, adjustable chemical structure. Notably, MOFs with large surface areas, tunable chemical structures, and high stability have been explored in various applications, whereas MXenes with good conductivity, excellent ion-transport characteristics, and ease of modification have exhibited great potential in biochemical sensing. This review first outlines the importance of taste sensors, their operation mechanism, and measuring methods in sensing utilization. Then, recent studies focusing on MOFs and MXenes for the detection of different tastes are discussed. Finally, future directions for biomimetic tongues based on MOFs and MXenes are discussed.

Bifunctional Smart Hydrogel Dressing with Strain Sensitivity and NIR-Responsive Performance

Smart response hydrogel has a broad application prospect in human health real-time monitoring due to its responses to a variety of stimuli. In this study, we developed a novel smart hydrogel dressing based on conductive MXene nanosheets and a temperature-sensitive PNIPAm polymer. γ-Methacryloxypropyltrimethoxysilane (KH570) was selected to functionalize the surface of MXene further to improve the interface compatibility between MXene and PNIPAm. Our prepared K-M/PNIPAm hydrogel was found to have a strain-sensitive property, as well as a respond to NIR phase change and volume change. When applied as a strain flexible sensor, this K-M/PNIPAm hydrogel exhibited a high strain sensitivity with a gauge factor (GF) of 4.491, a broad working strain range of ≈250%, a fast response of ∼160 ms, and good cycle stability (i.e., 3000 s at 20% strain). Besides, this K-M/PNIPAm hydrogel can be used as an efficient NIR light-controlled drug release carrier to achieve on-demand drug release. This work paved the way for the application of smart response hydrogel in human health real-time monitoring and NIR-controlled drug release functions.