Stereolithography Three-Dimensional Printing Solid Polymer Electrolytes for All-Solid-State Lithium Metal Batteries

Ionic Covalent Organic Framework Solid-State Electrolytes

Rechargeable secondary batteries, widely used in modern technology, are essential for mobile and consumer electronic devices and energy storage applications. Lithium (Li)-ion batteries are currently the most popular choice due to their decent energy density. However, the increasing demand for higher energy density has led to the development of Li metal batteries (LMBs). Despite their potential, the commonly used liquid electrolyte-based LMBs present serious safety concerns, such as dendrite growth and the risk of fire and explosion. To address these issues, using solid-state electrolytes in batteries has emerged as a promising solution. In this Perspective, recent advancements are discussed in ionic covalent organic framework (ICOFs)-based solid-state electrolytes, identify current challenges in the field, and propose future research directions. Highly crystalline ion conductors with polymeric versatility show promise as the next-generation solid-state electrolytes. Specifically, the use of anionic or cationic COFs is examined for Li-based batteries, highlight the high interfacial resistance caused by the intrinsic brittleness of crystalline ICOFs as the main limitation, and presents innovative ideas for developing all- and quasi-solid-state batteries using ICOF-based solid-state electrolytes. With these considerations and further developments, the potential for ICOFs is optimistic about enabling the realization of high-energy-density all-solid-state LMBs.

A Large-Scale Fabrication of Flexible, Ultrathin, and Robust Solid Electrolyte for Solid-State Lithium-Sulfur Batteries

All-solid-state lithium metal batteries (ASSLMBs) are considered as the most promising candidates for the next-generation high-safety batteries. To achieve high energy density in ASSLMBs, it is essential that the solid-state electrolytes (SSEs) are lightweight, thin, and possess superior electrochemical stability. In this study, a feasible and scalable fabrication approach to construct 3D supporting skeleton using an electro-blown spinning technique is proposed. This skeleton not only enhances the mechanical strength but also hinders the migration of Li-salt anions, improving the lithium-ion transference number of the SSE. This provides a homogeneous distribution of Li-ion flux and local current density, promoting uniform Li deposition. As a result, based on the mechanically robust and thin SSEs, the Li symmetric cells show outstanding Li plating/stripping reversibility. Besides, a stable interface contact between SSE and Li anode has been established with the formation of an F-enriched solid electrolyte interface layer. The solid-state Li|sulfurized polyacrylonitrile (Li|SPAN) cell achieves a capacity retention ratio of 94.0% after 350 cycles at 0.5 C. Also, the high-voltage Li|LCO cell shows a capacity retention of 92.4% at 0.5 C after 500 cycles. This fabrication approach for SSEs is applicable for commercially large-scale production and application in high-energy-density and high-safety ASSLMBs.

Efficient Ion Percolating Network for High-Performance All-Solid-State Cathodes

All-solid-state lithium batteries (ASSLBs) face critical challenges of low cathode loading and poor rate performances, which handicaps their energy/power densities. The widely-accepted aim of high ionic conductivity and low interfacial resistance seems insufficient to overcome these challenges. Here, it is revealed that an efficient ion percolating network in the cathode exerts a more critical influence on the electrochemical performance of ASSLBs. By constructing vertical alignment of Li0.35La0.55TiO3 nanowires (LLTO NWs) in solid-state cathode through magnetic manipulation, the ionic conductivity of the cathode increases twice compared with the cathode consisted of randomly distributed LLTO NWs. The all-solid-state LiFePO4/Li cells using poly(ethylene oxide) as the electrolyte is able to deliver high capacities of 151 mAh g-1 (2 C) and 100 mAh g-1 (5 C) at 60 °C, and a room-temperature capacity of 108 mAh g-1 can be achieved at a charging rate of 2 C. Furthermore, the cell can reach a high areal capacity of 3 mAh cm-2 even with a practical LFP loading of 20 mg cm-2. The universality of this strategy is also presented showing the demonstration in LiNi0.8Co0.1Mn0.1O2 cathodes. This work offers new pathways for designing ASSLBs with improved energy/power densities.

The status and challenging perspectives of 3D-printed micro-batteries

In the era of the Internet of Things and wearable electronics, 3D-printed micro-batteries with miniaturization, aesthetic diversity and high aspect ratio, have emerged as a recent innovation that solves the problems of limited design diversity, poor flexibility and low mass loading of materials associated with traditional power sources restricted by the slurry-casting method. Thus, a comprehensive understanding of the rational design of 3D-printed materials, inks, methods, configurations and systems is critical to optimize the electrochemical performance of customizable 3D-printed micro-batteries. In this review, we offer a key overview and systematic discussion on 3D-printed micro-batteries, emphasizing the close relationship between printable materials and printing technology, as well as the reasonable design of inks. Initially, we compare the distinct characteristics of various printing technologies, and subsequently emphatically expound the printable components of micro-batteries and general approaches to prepare printable inks. After that, we focus on the outstanding role played by 3D printing design in the device architecture, battery configuration, performance improvement, and system integration. Finally, the future challenges and perspectives concerning high-performance 3D-printed micro-batteries are adequately highlighted and discussed. This comprehensive discussion aims at providing a blueprint for the design and construction of next-generation 3D-printed micro-batteries.

Solid-state, liquid-free ion-conducting elastomers: rising-star platforms for flexible intelligent devices

Soft ionic conductors have emerged as a powerful toolkit to engineer transparent flexible intelligent devices that go beyond their conventional counterparts. Particularly, due to their superior capacities of eliminating the evaporation, freezing and leakage issues of the liquid phase encountered with hydrogels, organohydrogels and ionogels, the emerging solid-state, liquid-free ion-conducting elastomers have been largely recognized as ideal candidates for intelligent flexible devices. However, despite their extensive development, a comprehensive and timely review in this emerging field is lacking, particularly from the perspective of design principles, advanced manufacturing, and distinctive applications. Herein, we present (1) the design principles and intriguing merits of solid-state, liquid-free ion-conducting elastomers; (2) the methods to manufacture solid-state, liquid-free ion-conducting elastomers with preferential architectures and functions using advanced technologies such as 3D printing; (3) how to leverage solid-state, liquid-free ion-conducting elastomers in exploiting advanced applications, especially in the fields of flexible wearable sensors, bioelectronics and energy harvesting; (4) what are the unsolved scientific and technical challenges and future opportunities in this multidisciplinary field. We envision that this review will provide a paradigm shift to trigger insightful thinking and innovation in the development of intelligent flexible devices and beyond.

3D Printing Manufacturing of Lithium Batteries: Prospects and Challenges toward Practical Applications

The manufacturing and assembly of components within cells have a direct impact on the sample performance. Conventional processes restrict the shapes, dimensions, and structures of the commercially available batteries. 3D printing, a novel manufacturing process for precision and practicality, is expected to revolutionize the lithium battery industry owing to its advantages of customization, mechanization, and intelligence. This technique can be used to effectively construct intricate 3D structures that enhance the designability, integrity, and electrochemical performance of both liquid- and solid-state lithium batteries. In this study, an overview of the development of 3D printing technologies is provided and their suitability for comparison with conventional printing processes is assessed. Various 3D printing technologies applicable to lithium-ion batteries have been systematically introduced, especially more practical composite printing technologies. The practicality, limitations, and optimization of 3D printing are discussed dialectically for various battery modules, including electrodes, electrolytes, and functional architectures. In addition, all-printed batteries are emphatically introduced. Finally, the prospects and challenges of 3D printing in the battery industry are evaluated.

Highly Efficient Aligned Ion-Conducting Network and Interface Chemistries for Depolarized All-Solid-State Lithium Metal Batteries

Improving the long-term cycling stability and energy density of all-solid-state lithium (Li)-metal batteries (ASSLMBs) at room temperature is a severe challenge because of the notorious solid-solid interfacial contact loss and sluggish ion transport. Solid electrolytes are generally studied as two-dimensional (2D) structures with planar interfaces, showing limited interfacial contact and further resulting in unstable Li/electrolyte and cathode/electrolyte interfaces. Herein, three-dimensional (3D) architecturally designed composite solid electrolytes are developed with independently controlled structural factors using 3D printing processing and post-curing treatment. Multiple-type electrolyte films with vertical-aligned micro-pillar (p-3DSE) and spiral (s-3DSE) structures are rationally designed and developed, which can be employed for both Li metal anode and cathode in terms of accelerating the Li+ transport within electrodes and reinforcing the interfacial adhesion. The printed p-3DSE delivers robust long-term cycle life of up to 2600 cycles and a high critical current density of 1.92 mA cm-2. The optimized electrolyte structure could lead to ASSLMBs with a superior full-cell areal capacity of 2.75 mAh cm-2 (LFP) and 3.92 mAh cm-2 (NCM811). This unique design provides enhancements for both anode and cathode electrodes, thereby alleviating interfacial degradation induced by dendrite growth and contact loss. The approach in this study opens a new design strategy for advanced composite solid polymer electrolytes in ASSLMBs operating under high rates/capacities and room temperature.

Technological Advances and Market Developments of Solid-State Batteries: A Review

Batteries are essential in modern society as they can power a wide range of devices, from small household appliances to large-scale energy storage systems. Safety concerns with traditional lithium-ion batteries prompted the emergence of new battery technologies, among them solid-state batteries (SSBs), offering enhanced safety, energy density, and lifespan. This paper reviews current state-of-the-art SSB electrolyte and electrode materials, as well as global SSB market trends and key industry players. Solid-state electrolytes used in SSBs include inorganic solid electrolytes, organic solid polymer electrolytes, and solid composite electrolytes. Inorganic options like lithium aluminum titanium phosphate excel in ionic conductivity and thermal stability but exhibit mechanical fragility. Organic alternatives such as polyethylene oxide and polyvinylidene fluoride offer flexibility but possess lower ionic conductivity. Solid composite electrolytes combine the advantages of inorganic and organic materials, enhancing mechanical strength and ionic conductivity. While significant advances have been made for composite electrolytes, challenges remain for synthesis intricacies and material stability. Nuanced selection of these electrolytes is crucial for advancing resilient and high-performance SSBs. Furthermore, while global SSB production capacity is currently below 2 GWh, it is projected to grow with a >118% compound annual growth rate by 2035, when the potential SSB market size will likely exceed 42 billion euros.

Efficient Bifunctional Photoelectric Integrated Cathode for Solar Energy Conversion and Storage

The integrated photoelectric battery serves as a compact and energy-efficient form for direct conversion and storage of solar energy compared to the traditional isolated PV-battery systems. However, combining efficient light harvesting and electrochemical energy storage into a single material is a great challenge. Here, a bifunctional lead phytate-cesium lead bromide (PbPA-CsPbBr3) cathode is explored for the solid-state batteries in terms of CsPbBr3 in situ grown on the PbPA framework. Specifically, CsPbBr3 nanocrystals generate electron-hole pairs under sunlight, the holes contribute to the lithium desorption of the discharged PbPA, and the electrons participate in the formation of the cathode interfacial film through oxygen reduction. The obtained solid-state photoelectric lithium-metal battery achieved a photoconversion efficiency of 0.72%, outperforming other systems under the same lighting conditions. The reasonable cathode design and its application in integrated solid-state batteries provide an efficient way for solar energy utilization.

3D printing of hierarchically micro/nanostructured electrodes for high-performance rechargeable batteries

3D printing, also known as additive manufacturing, is capable of fabricating 3D hierarchical micro/nanostructures by depositing a layer-upon-layer of precursor materials and solvent-based inks under the assistance of computer-aided design (CAD) files. 3D printing has been employed to construct 3D hierarchically micro/nanostructured electrodes for rechargeable batteries, endowing them with high specific surface areas, short ion transport lengths, and high mass loading. This review summarizes the advantages and limitations of various 3D printing methods and presents the recent developments of 3D-printed electrodes in rechargeable batteries, such as lithium-ion batteries, sodium-ion batteries, and lithium-sulfur batteries. Furthermore, the challenges and perspectives of the 3D printing technique for electrodes and rechargeable batteries are put forward. This review will provide new insight into the 3D printing of hierarchically micro/nanostructured electrodes in rechargeable batteries and promote the development of 3D printed electrodes and batteries in the future.

3D Printing-Enabled Design and Manufacturing Strategies for Batteries: A Review

Lithium-ion batteries (LIBs) have significantly impacted the daily lives, finding broad applications in various industries such as consumer electronics, electric vehicles, medical devices, aerospace, and power tools. However, they still face issues (i.e., safety due to dendrite propagation, manufacturing cost, random porosities, and basic & planar geometries) that hinder their widespread applications as the demand for LIBs rapidly increases in all sectors due to their high energy and power density values compared to other batteries. Additive manufacturing (AM) is a promising technique for creating precise and programmable structures in energy storage devices. This review first summarizes light, filament, powder, and jetting-based 3D printing methods with the status on current trends and limitations for each AM technology. The paper also delves into 3D printing-enabled electrodes (both anodes and cathodes) and solid-state electrolytes for LIBs, emphasizing the current state-of-the-art materials, manufacturing methods, and properties/performance. Additionally, the current challenges in the AM for electrochemical energy storage (EES) applications, including limited materials, low processing precision, codesign/comanufacturing concepts for complete battery printing, machine learning (ML)/artificial intelligence (AI) for processing optimization and data analysis, environmental risks, and the potential of 4D printing in advanced battery applications, are also presented.

Realization of High Loading Density Lithium Polymer Batteries by Optimizing Lithium-Ion Transport and Electronic Conductivity

Lithium polymer batteries (LPBs) with a high energy density and safety are being actively studied for their use as an energy storage system. However, bottlenecks to their development include charge-transport resistance and poor interfacial contact. In this paper, we introduce carbon nanofiber (CNF) as a conductive additive and the optimization of porosity in the electrode by calendering to realize a high loading density LPB. A simple dispersion strategy is applied to homogeneously disperse nanofiber additives in the electrode to achieve high electronic conductivity. Calendering with optimized pressing degree was performed on the CNF-based electrode to enhance lithium-ion transport and electron conduction in the LPB. The optimal pressing conditions were confirmed by measuring the electronic conductivity, internal resistance, lithium-ion diffusion coefficient, and charge transport characteristics of the cells. When the electrode was pressed by 35%, optimum electrode wettability by solid polymer electrolyte and contact between particles and current collector were achieved, resulting in the high performance of the LPB. Finally, at the optimized pressing degree, we successfully demonstrate 90% cycle retention during 100 cycles and an improvement of the volumetric energy density by over seven-fold.

All-Solid-State Thin Film Lithium/Lithium-Ion Microbatteries for Powering the Internet of Things

As the world steps into the era of Internet of Things (IoT), numerous miniaturized electronic devices requiring autonomous micropower sources will be connected to the internet. All-solid-state thin-film lithium/lithium-ion microbatteries (TFBs) combining solid-state battery architecture and thin-film manufacturing are regarded as ideal on-chip power sources for IoT-enabled microelectronic devices. However, unlike commercialized lithium-ion batteries, TFBs are still in the immature state, and new advances in materials, manufacturing, and structure are required to improve their performance. In this review, the current status and existing challenges of TFBs for practical application in internet-connected devices for the IoT are discussed. Recent progress in thin-film deposition, electrode and electrolyte materials, interface modification, and 3D architecture design is comprehensively summarized and discussed, with emphasis on state-of-the-art strategies to improve the areal capacity and cycling stability of TFBs. Moreover, to be suitable power sources for IoT devices, the design of next-generation TFBs should consider multiple functionalities, including wide working temperature range, good flexibility, high transparency, and integration with energy-harvesting systems. Perspectives on designing practically accessible TFBs are provided, which may guide the future development of reliable power sources for IoT devices.

Fabrication of modern lithium ion batteries by 3D inkjet printing: opportunities and challenges

Inkjet printing (IJP) is a prospective additive manufacturing technology that enables the rapid and precise deposition of thin films or patterns. It offers numerous advantages over other thin-film manufacturing processes, including cost-effectiveness, ease of use, reduced waste material, and scalability. The key advantage of this technique is the ability of the fabrication of complex patterns with very high precision. The IJP gives the possibility of building three-dimensional (3D) structures on the microscale, which is beneficial for modern Li-Ion batteries (LIBs) and All-Solid-State Li-Ion Batteries (ASSLIBs). In contrast to typical laminated composite electrodes manufactured by tape casting and calendaring, 3D electrode design allows the electrolyte to penetrate through the electrode volume, increasing the surface-to-volume ratio and reducing ion diffusion paths. Thus, 3D electrodes/electrolyte structures are one of the most promising strategies for producing next-generation lithium-ion batteries with enhanced electrochemical performance. Although in the literature review, the IJP is frequently reported as a future perspective for the fabrication of 3D electrodes/electrolytes structures for LIBs, only a few works focus on this subject. In this review, we summarize the previous studies devoted to the topic and discuss different bottlenecks and challenges limiting further development.

3D Printing Nanostructured Solid Polymer Electrolytes with High Modulus and Conductivity

The development of advanced solid-state energy-storage devices is contingent upon finding new ways to produce and manufacture scalable, high-modulus solid-state electrolytes that can simultaneously provide high ionic conductivity and robust mechanical integrity. In this work, an efficient one-step process to manufacture solid polymer electrolytes composed of nanoscale ion-conducting channels embedded in a rigid crosslinked polymer matrix via Digital Light Processing 3D printing is reported. A visible-light-mediated polymerization-induced microphase-separation approach is utilized, which produces materials with two chemically independent nanoscale domains with highly tunable nanoarchitectures. By producing materials containing a poly(ethylene oxide) domain swelled with an ionic liquid, robust solid polymer electrolytes with outstanding room-temperature (22 °C) shear modulus (G' > 10⁸ Pa) and ionic conductivities up to σ = 3 × 10^-4 S cm^-1 are achieved. The nanostructured 3D-printed electrolytes are fabricated into a custom geometry and employed in a symmetric carbon supercapacitor, demonstrating the scalability of the fabrication and the functionality of the electrolyte. Critically, these high-performance materials are manufactured on demand using inexpensive and commercially available 3D printers, which allows the facile modular design of solid polymer electrolytes with custom geometries.

Smart Manufacturing Processes of Low-Tortuous Structures for High-Rate Electrochemical Energy Storage Devices

To maximize the performance of energy storage systems more effectively, modern batteries/supercapacitors not only require high energy density but also need to be fully recharged within a short time or capable of high-power discharge for electric vehicles and power applications. Thus, how to improve the rate capability of batteries or supercapacitors is a very important direction of research and engineering. Making low-tortuous structures is an efficient means to boost power density without replacing materials or sacrificing energy density. In recent years, numerous manufacturing methods have been developed to prepare low-tortuous configurations for fast ion transportation, leading to impressive high-rate electrochemical performance. This review paper summarizes several smart manufacturing processes for making well-aligned 3D microstructures for batteries and supercapacitors. These techniques can also be adopted in other advanced fields that require sophisticated structural control to achieve superior properties.

Additive Manufacturing Polyurethane Acrylate via Stereolithography for 3D Structure Polymer Electrolyte Application

Additive manufacturing (AM), also known as 3D-printing technology, is currently integrated in many fields as it possesses an attractive fabrication process. In this work, we deployed the 3D-print stereolithography (SLA) method to print polyurethane acrylate (PUA)-based gel polymer electrolyte (GPE). The printed PUA GPE was then characterized through several techniques, such as Fourier transform infrared (FTIR), electrochemical impedance spectroscopy (EIS), X-ray diffraction analysis (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and scanning electron microscope (SEM). The printed GPE exhibited high ionic conductivity of 1.24 × 10-3 S cm-1 at low-lithium-salt content (10 wt.%) in ambient temperature and favorable thermal stability to about 300 °C. The FTIR results show that addition of LiClO4 to the polymer matrix caused a shift in carbonyl, ester and amide functional groups. In addition, FTIR deconvolution peaks of LiClO4 show 10 wt.% has the highest amount of free ions, in line with the highest conductivity achieved. Finally, the PUA GPE was printed into 3D complex structure to show SLA flexibility in designing an electrolyte, which could be a potential application in advanced battery fabrication.

Material Design for Enhancing Properties of 3D Printed Polymer Composites for Target Applications

Polymer composites are becoming an important class of materials for a diversified range of industrial applications due to their unique characteristics and natural and synthetic reinforcements. Traditional methods of polymer composite fabrication require machining, manual labor, and increased costs. Therefore, 3D printing technologies have come to the forefront of scientific, industrial, and public attention for customized manufacturing of composite parts having a high degree of control over design, processing parameters, and time. However, poor interfacial adhesion between 3D printed layers can lead to material failure, and therefore, researchers are trying to improve material functionality and extend material lifetime with the addition of reinforcements and self-healing capability. This review provides insights on different materials used for 3D printing of polymer composites to enhance mechanical properties and improve service life of polymer materials. Moreover, 3D printing of flexible energy-storage devices (FESD), including batteries, supercapacitors, and soft robotics using soft materials (polymers), is discussed as well as the application of 3D printing as a platform for bioengineering and earth science applications by using a variety of polymer materials, all of which have great potential for improving future conditions for humanity and planet Earth.

3D Printing for Solid-State Energy Storage

Ever-growing demand to develop satisfactory electrochemical devices has driven cutting-edge research in designing and manufacturing reliable solid-state electrochemical energy storage devices (EESDs). 3D printing, a precise and programmable layer-by-layer manufacturing technology, has drawn substantial attention to build advanced solid-state EESDs and unveil intrinsic charge storage mechanisms. It provides brand-new opportunities as well as some challenges in the field of solid-state energy storage. This review focuses on the topic of 3D printing for solid-state energy storage, which bridges the gap between advanced manufacturing and future EESDs. It starts from a brief introduction followed by an emphasis on 3D printing principles, where basic features of 3D printing and key issues for solid-state energy storage are both reviewed. Recent advances in 3D printed solid-state EESDs including solid-state batteries and solid-state supercapacitors are then summarized. Conclusions and perspectives are also provided regarding the further development of 3D printed solid-state EESDs. It can be expected that advanced 3D printing will significantly promote future evolution of solid-state EESDs.

Spiral- and meridian-patterned spheres self-assembled from block copolymer/homopolymer binary systems

Spiral nanostructures, mainly in the 2D form, have been observed in polymer self-assembly, while well-defined 3D spirals are rarely reported. Here we report that a binary system containing polypeptide-based block copolymers and homopolymers can self-assemble into well-defined spiral spheres (3D spirals), in which the homopolymers form the core and the copolymers form the spirals. Upon increasing the preparation temperature, meridian spheres were obtained. Mixing polypeptide block copolymers with opposite backbone chirality also leads to the formation of meridian spheres. In the meridian patterns, a tighter packing manner of the phenyl groups appended to the polypeptide blocks was observed, which is responsible for the spiral-to-meridian transitions. This work enriches the research of spiral assemblies and provides a facile route to switch chiral/achiral nanostructures by regulating the packing manner of the pendant groups.

Electrocatalytic NiCo2O4 Nanofiber Arrays on Carbon Cloth for Flexible and High-Loading Lithium-Sulfur Batteries

Lithium-sulfur batteries have ultrahigh theoretical energy densities, which makes them one of the most promising next-generation energy storage systems. However, it is still difficult to achieve large-scale commercialization because of the severe lithium polysulfide (LiPS) shuttle effect and low sulfur loading. Here, we report a flexible lithium-sulfur battery of a high sulfur loading with the assistance of NiCo₂O₄ nanofiber array grown carbon cloth. The NiCo₂O₄ nanofibers are ideal electrocatalysts for accelerating LiPS conversion kinetics through strong chemical interactions. Therefore, the composite cathode delivers a high specific capacity of 1280 mAh g^-1 at 0.2 C with a sulfur loading of 3.5 mg cm^-2, and it can maintain a high specific capacity of 660 mAh g^-1 after 200 cycles, showing a good cycle stability. The "layer-by-layer" stacking strategy enables the Li-S battery with a high S loading of ∼9.0 mg cm^-2 to deliver a high areal capacity of 8.9 mAh cm^-2.