Leaf-inspired design of mesoporous Sb2S3/N-doped Ti3C2Tx composite towards fast sodium storage

The Renaissance of Poly(3-hexylthiophene) as a Promising Hole-Transporting Material Toward Efficient and Stable Perovskite Solar Cells

To push the commercialization of the promising photovoltaic technique of perovskite solar cells (PSCs), the three-element golden law of efficiency, stability, and cost should be followed. As the key component of PSCs, hole-transporting materials (HTMs) involving widely-used organic semiconductors such as 2,2',7,7'-tetrakis-(N,N-di-4-methoxyphenylamino)-9,9'-spirobifluorene (Spiro-OMeTAD) or poly(triarylamine) (PTAA) usually suffer high-cost preparation and low operational stability. Fortunately, the studies on the classical p-type polymer poly(3-hexylthiophene) (P3HT) as an alternative HTM have recently sparked a broad interest due to its low-cost synthesis, excellent batch-to-batch purity, superior hole conductivity as well as controllable and stable film morphology. Despite this, the device efficiency still lags behind P3HT-based PSCs mainly owing to the mismatched energy level and poor interfacial contact between P3HT and the perovskite layer. Hence, in this review, the study timely summarizes the developed strategies for overcoming the corresponding issues such as interface engineering, morphology regulation, and formation of composite HTMs from which some critical clues can be extracted to provide guidance for further boosting the efficiency and stability of P3HT-based devices. Finally, in the outlook, the future research directions either from the viewpoint of material design or device engineering are outlined.

High-Rate SiO Lithium-Ion Battery Anode Enabled by Rationally Interfacial Hybrid Encapsulation Engineering

The development of a high-rate SiO lithium-ion battery anode is seriously limited by its low intrinsic conductivity, sluggish interfacial charge transfer (ICT), and unstable dynamic interface. To tackle the above issues, interfacial encapsulation engineering for effectively regulating the interfacial reaction and thus realizing a stable solid electrolyte interphase is significantly important. Hybrid coating, which aims to enhance the coupled e-/Li+ transport via the employment of dual layers, has emerged as a promising strategy. Herein, we construct a hybrid MXene-graphene oxide (GO) coating layer on the SiO microparticles. In the design, Ti3C2Tx MXene acts as a "bridge", which forms a close covalent connection with SiO and GO through Ti-O-Si and Ti-O-C bonds, respectively, thus greatly reducing the ICT resistance. Moreover, the Ti3C2Tx with rich surface groups (e.g., -OH, -F) and GO outer layers with an intertwined porous framework synergistically enable the pseudocapacitance dominated behavior, which is beneficial for fast lithium-ion storage. Accordingly, the as-made Si@MXene@GO anode exhibits considerably reinforced lithium-ion storage performance in terms of superior rate performance (1175.9 mA h g-1 at 5 A g-1) and long cycling stability (1087.6 mA h g-1 capacity retained after 1000 cycles at 2.0 A g-1). In-depth interfacial chemical composition analysis further reveals that an inorganically rich interphase with a gradient distribution of LiF and Li2O formed at the electrolyte/anode interface ensures mechanical stability during repeated cycles. This work paves a feasible way for maximizing the potential of SiO anodes toward fast-charging lithium-ion batteries.

High Proportion of Active Nitrogen-Doped Hard Carbon Based on Mannich Reaction as Anode Material for High-Performance Sodium-Ion Batteries

The potential for energy storage in carbonaceous materials is well known. Heteroatom doping - particularly nitrogen doping - can further enhance their electrochemical performance. The type of N configuration determines the reactivity of doped carbon. It remains a challenge, however, to achieve a high ratio of active N (N-5) in N-doped carbon. In this study, a high proportion of active nitrogen-doped hard carbon (PTA-Lys-800) is synthesized by the classical Mannich reaction, using tannic acid (TA) and amino acid as precursors. For sodium-ion batteries (SIBs), PTA-Lys-800 provides outstanding cycling stability and rate performance (338.8 mAh g^-1 at 100 mA g^-1 for 100 cycles, a capacity retention of 86 %; 131.1 mAh g^-1 at 4 A g^-1 after 5000 cycles). The excellent performance of PTA-Lys-800 is attributed to stable hierarchical pore structure, abundant defects, and a high proportion of N-5 formed during the carbonization process. Based on a detailed fundamental analysis, the pseudocapacitance mechanism is found to contribute to the higher sodium storage process in PTA-Lys-800. The Na-adsorption mechanism is further explored through ex situ Raman spectroscopy. A new method is presented for designing carbonaceous anode materials with high capacity and long cycle life.

Sodium titanium phosphate nanocube decorated on tablet-like carbon for robust sodium storage performance at low temperature

Sodium-ion batteries, featuring resource abundance and similar working mechanisms to lithium-ion batteries, have gained extensive interest in both scientific exploration and industrial applications. However, the extremely sluggish reaction kinetics of charge carrier (Na+) at subzero temperatures significantly reduces their specific capacities and cycling life. Herein, this study presents a novel hybrid structure with sodium titanium phosphate (NaTi2(PO4)3, NTP) nanocube in-situ decorated on tablet-like carbon (NTP/C), which manifests superior sodium storage performances at low temperatures. At even -25 °C, a stable cycling with a specific capacity of 94.3 mAh/g can still be maintained after 200 cycles at 0.5 A/g, delivering a high capacity retention of 91.5 % compared with that at room temperature, along with an excellent rate capability. Generally, the superionic conductor structure, flat voltage plateaus, as well as the conductive carbonaceous framework can efficiently facilitate the charge transfer, accelerate the diffusion of Na+, and decrease the electrochemical polarization. Moreover, further investigations on diffusion kinetics, solid electrolyte interface layer, and the interaction between NTP and carbonaceous skeleton reveal its high Na+ diffusion coefficient, robust solid electrolyte interface, and strong electronic interaction, thus contributing to the superior capacity retentions at subzero temperatures.

A Novel Hierarchical Structure of SnCu2Se4/d-Ti3C2Tx/NPC for a Lithium/Sodium Ion Battery and Hybrid Capacitor with Long-Term Cycling Stabilities

To alleviate kinetics imbalance and capacity insufficiency simultaneously, a novel hierarchical structure (SnCu₂Se₄/d-Ti₃C₂T_x/NPC) composed of delaminated Ti₃C₂T_x, SnCu₂Se₄ nanoparticles, and N-doped porous carbon layers is designed as a battery-type anode for lithium/sodium ion hybrid capacitor (LIC/SIC). The combination of SnCu₂Se₄ nanoparticles with high specific capacity, d-Ti₃C₂T_x with accelerated ion diffusion path, and NPC with enhanced electronic conductivity makes the SnCu₂Se₄/d-Ti₃C₂T_x/NPC composite possess excellent cycling stabilities in half-cell lithium-ion and sodium-ion batteries (LIB and SIB), with capacities of 114 mAh g^-1 after 6000 cycles at 10 A g^-1 for LIB and 296 mAh g^-1 after 900 cycles at 1.0 A g^-1 for SIB. The rate performance is also outstanding, with recovered capacity of 738 mAh g^-1 at 0.1 A g^-1 after cycles at current densities up to 50 A g^-1 for LIB. Subsequently, LIC and SIC based on the SnCu₂Se₄/d-Ti₃C₂T_x/NPC anode and activated carbon cathode exhibit high energy densities of 147.9 and 158.6 Wh kg^-1 at a power density of 100 W kg^-1, respectively. They also possess distinctive long lifespans with capacity retentions of 78 and 81% after 10,000 cycles at 1.0 A g^-1, respectively, demonstrating the feasibility of SnCu₂Se₄/d-Ti₃C₂T_x/NPC toward energy devices requiring high energy density, power density, and long-term stability.

A unique two-phase heterostructure with cubic NiSe2 and orthorhombic NiSe2 for enhanced lithium ion storage and electrocatalysis

Two-phase heterostructures have received tremendous attention in energy-related fields as high-performance electrode materials. However, heterogeneous interfaces are usually constructed by introducing foreign elements, which disturbs the investigation of the intrinsic effect of the two-phase heterostructure. Herein, unique heterostructures constructed with orthorhombic NiSe₂ and cubic NiSe₂ phases are developed, which are embedded in in situ formed porous carbon from metal-organic frameworks (MOFs) (O/C-NiSe₂@C). Precisely-controlled selenylation of MOFs is crucial for the formation of the O/C-NiSe₂ heterostructure. The heterogeneous interfaces with lattice dislocations and charge distribution are conducive to the high-speed transfer of electrons and ions during electrochemical processes, so as to improve the electrochemical reaction kinetics for lithium-ion storage and the hydrogen evolution reaction (HER). When used as the anode of lithium-ion batteries (LIBs), O/C-NiSe₂@C shows a superior electrochemical performance to the counterparts with only the cubic phase (C-NiSe₂@C), in view of the cycling performance (719.3 mA h g^-1 at 0.1 A g^-1 for 100 cycles; 456.3 mA h g^-1 at 1 A g^-1 for 1000 cycles) and rate capabilities (344.8 mA h g^-1 at 4 A g^-1). Furthermore, O/C-NiSe₂@C also exhibits better HER properties than C-NiSe₂@C, that is, much lower overpotentials of 154 mV and 205 mV in 0.5 M H₂SO₄ and 1 M KOH, respectively, at 10 mA cm^-2, a smaller Tafel slope as well as stable electrocatalytic activities for 2000 cycles/10 h. Preliminary observations indicate that the unique orthorhombic/cubic two-phase heterostructure could significantly improve the electrochemical performance of NiSe₂ without additional modifications such as doping, suggesting the O/C-NiSe₂ heterostructure as a promising bifunctional electrode for energy conversion and storage applications.

High-capacity and ultrastable lithium storage in SnSe2-SnO2@NC microbelts enabled by heterostructures

The ingenious design of high-performance tin-based lithium-ion batteries (LIBs) is challenging due to their poor conductivity and drastic volume change during continuous lithiation/delithiation cycles. Herein, we present a strategy to confine heterostructured SnSe₂-SnO₂ nanoparticles into macroscopic nitrogen-doped carbon microbelts (SnSe₂-SnO₂@NC) as anode materials for LIBs. The composites exhibit an excellent specific capacity of 436.3 mA h g^-1 even at 20 A g^-1 and an ultrastable specific capacity of 632.7 mA h g^-1 after 2800 cycles at 5 A g^-1. Density Functional Theory (DFT) calculations reveal that metallic SnSe₂-SnO₂ heterostructures endow the lithium atoms at the interface with high adsorption energy, which promotes the anchoring of Li atoms, and enhances the electrical conductivity of the anode materials. This demonstrates the superior Li⁺ storage performance of the SnSe₂-SnO₂@NC microbelts as anode materials.

K-Functionalized Carbon Quantum Dots-Induced Interface Assembly of Carbon Nanocages for Ultrastable Potassium Storage Performance

Carbon nanocages (CNCs), with unique merits of morphology and structure, have attracted increasing attention for energy storage and conversion. However, the synthesis of CNCs reported so far suffers from relatively harsh conditions and expensive raw materials. Herein, porous CNCs are intelligently designed using low-cost glucose as the carbon precursor via a facile K-functionalized carbon quantum dots (K-CQDs)-induced assembly route under hydrothermal process. The resulting CNCs have a unique cage-like structure, large surface area, and rich carboxyl groups. With these elegant structural merits, the as-made CNCs anode shows a high reversible capacity of 270 mAh g^-1 at 100 mA g^-1 after 200 cycles and a long-term cycling stability of 206 mAh g^-1 at 2000 mA g^-1 after 4000 cycles. An intercalation reaction mechanism with the K⁺ intercalation compound is further identified through an in-situ Raman technique. Density functional theory simulations reveal that abundant carboxyl groups inherited from K-CQDs can significantly promote the potassium storage capacities of the CNCs electrode.

Recent Advances in Antimony Sulfide-Based Nanomaterials for High-Performance Sodium-Ion Batteries: A Mini Review

Recently, sodium-ion batteries (SIBs) have attracted extensive attention as potential alternatives to lithium-ion batteries (LIBs) due to the abundance, even distribution, low cost, and environmentally friendly nature of sodium. However, sodium ions are larger than lithium ions so that the anode materials of LIBs are not suitable for SIBs. Therefore, many negative electrode materials have been investigated. Among them, Sb₂S₃-based nanomaterials have gradually become a research focus due to their high theoretical specific capacity, good thermal stability, simple preparation, and low price. In this review, the research progress of Sb₂S₃-based nanomaterials in the SIB field in recent years is summarized, including Sb₂S₃, Sb₂S₃/carbon composites, Sb₂S₃/graphene composites, and Sb₂S₃/M_xS_y composites. Furthermore, the challenges and prospects for the development of Sb₂S₃-based nanomaterials are also put forward. We hope this review will contribute to the design and manufacture of high-performance SIBs and promote its practical application.

Recent advances of metal telluride anodes for high-performance lithium/sodium-ion batteries

Metal tellurides (MTs) have emerged as highly promising candidate anode materials for state-of-the-art lithium-ion batteries (LIBs) and sodium ion batteries (SIBs). This is owing to the unique crystal structure, high intrinsic conductivity, and high trap density of such materials. The present work delivers a detailed discussion on the latest research and progress associated with the use of MTs for LIBs/SIBs with a focus on reaction mechanisms, challenges, electrochemical performance, and synthesis strategies. Further, the prospects and future development of MT anode materials are discussed in terms of strategies to overcome the existing limitations. This review provides both an in-depth understanding of MTs and provides the driving force for expanding research on MTs for energy storage and conversion applications.

Constructing Heterostructured Bimetallic Selenides on an N-Doped Carbon Nanoframework as Anodes for Ultrastable Na-Ion Batteries

Transition-metal selenides have been recognized as a class of promising anode materials for sodium-ion batteries (SIBs) on account of their high capacity. Nevertheless, the sluggish conversion kinetics and rapid capacity decay caused by insufficient conductivity and volume change restrain their applications. Herein, hollow heterostructured bimetallic selenides embedded in an N-doped carbon nanoframework (H-CoSe₂/ZnSe@NC) were prepared via a facile template-engaged method. Benefiting from the rich defect at the phase boundary of the CoSe₂/ZnSe heterostructure, pre-reserved cavity, and enhanced structure rigidity, the abovementioned issues are resolved at once, and the accelerated charge transportation kinetics traced by spectroscopy techniques and theoretical calculations certify the interface effect in the capacity release. In addition, ex situ X-ray photoelectron spectroscopy, X-ray diffraction, and high-resolution transmission electron microscopy all confirm the high-reversible electrochemical conversion mechanism in H-CoSe₂/ZnSe@NC. Together with a reasonable structural architecture and the highly reversible conversion reaction, H-CoSe₂/ZnSe@NC displays a prominent rate capacity (244.8 mA h g^-1 at 10 A g^-1) as well as an ultralong lifespan (10,000 cycles at 10 A g^-1), highlighting the significance of structure control in fabricating high-performance anodes for SIBs.

Interfacial Covalent Bonding Endowing Ti3 C2 -Sb2 S3 Composites High Sodium Storage Performance

Antimony sulfide is attracting enormous attention due to its remarkable theoretical capacity as anode for sodium-ion batteries (SIBs). However, it still suffers from poor structural stability and sluggish reaction kinetics. Constructing covalent chemical linkage to anchor antimony sulfide on two-dimension conductive materials is an effective strategy to conquer the challenges. Herein, Ti₃ C₂ -Sb₂ S₃ composites are successfully achieved with monodispersed Sb2S3 uniformly pinned on the surface of Ti₃ C₂ T_x MXene through covalent bonding of Ti-O-Sb and S-Ti. Ti₃ C₂ T_x MXene serves as both charge storage contributor and flexible conductive buffer to sustain the structural integrity of the electrode. Systematic analysis indicates that construction of efficient interfacial chemical linkage could bridge the physical gap between Sb2S3 nanoparticles and Ti₃ C₂ T_x MXene, thus promoting the interfacial charge transfer efficiency. Furthermore, the interfacial covalent bonding could also effectively confine Sb2S3 nanoparticles and the corresponding reduced products on the surface of Ti₃ C₂ T_x MXene. Benefited from the unique structure, Ti₃ C₂ -Sb₂ S₃ anode delivers a high reversible capacity of 475 mAh g^-1 at 0.2 A g^-1 after 300 cycles, even retaining 410 mAh g^-1 at 1.0 A g^-1 after 500 cycles. This strategy is expected to shed more light on interfacial chemical linkage towards rational design of advanced materials for SIBs.

Microscale Silicon-Based Anodes: Fundamental Understanding and Industrial Prospects for Practical High-Energy Lithium-Ion Batteries

To accelerate the commercial implementation of high-energy batteries, recent research thrusts have turned to the practicality of Si-based electrodes. Although numerous nanostructured Si-based materials with exceptional performance have been reported in the past 20 years, the practical development of high-energy Si-based batteries has been beset by the bias between industrial application with gravimetrical energy shortages and scientific research with volumetric limits. In this context, the microscale design of Si-based anodes with densified microstructure has been deemed as an impactful solution to tackle these critical issues. However, their large-scale application is plagued by inadequate cycling stability. In this review, we present the challenges in Si-based materials design and draw a realistic picture regarding practical electrode engineering. Critical appraisals of recent advances in microscale design of stable Si-based materials are presented, including interfacial tailoring of Si microscale electrode, surface modification of SiO_x microscale electrode, and structural engineering of hierarchical microscale electrode. Thereafter, other practical metrics beyond active material are also explored, such as robust binder design, electrolyte exploration, prelithiation technology, and thick-electrode engineering. Finally, we provide a roadmap starting with material design and ending with the remaining challenges and integrated improvement strategies toward Si-based full cells.

Engineering Nanostructured Antimony-Based Anode Materials for Sodium Ion Batteries

Sodium-ion batteries (SIBs) are considered a potential alternative to lithium-ion batteries (LIBs) for energy storage due to their low cost and the large abundance of sodium resources. The search for new anode materials for SIBs has become a vital approach to satisfying the ever-growing demands for better performance with higher energy/power densities, improved safety and a longer cycle life. Recently, antimony (Sb) has been extensively researched as a promising candidate due to its high specific capacity through an alloying/dealloying process. In this review article, we will focus on different categories of the emerging Sb based anode materials with distinct sodium storage mechanisms including Sb, two-dimensional antimonene and antimony chalcogenide (Sb2S3 and Sb2Se3). For each part, we emphasize that the novel construction of an advanced nanostructured anode with unique structures could effectively improve sodium storage properties. We also highlight that sodium storage capability can be enhanced through designing advanced nanocomposite materials containing Sb based materials and other carbonaceous modification or metal supports. Moreover, the recent advances in operando/in-situ investigation of its sodium storage mechanism are also summarized. By providing such a systematic probe, we aim to stress the significance of novel nanostructures and advanced compositing that would contribute to enhanced sodium storage performance, thus making Sb based materials as promising anodes for next-generation high-performance SIBs.