Kinetics Of Electrode Reactions Research Articles

Constructing LiF-Dominated Interphases with Polymer Interwoven Outer Layer Enables Long-Term Cycling of Si Anodes.

Constructing a robust solid electrolyte interphase (SEI) is extremely critical to developing high-energy-density silicon (Si)-based lithium-ion batteries. However, it is still elusive how to accurately manipulate the chemical composition and structure of the SEI layer. Herein, a LiF-dominated SEI film intertwined by a highly elastic polymer is achieved by regulating the defluorination mechanism of the fluorinated carbonate additive on the Si electrode surface. The experimental and computational results confirm that the decomposition route of trans-difluoroethylene carbonate (DFEC) molecules can be significantly altered in the presence of lithium difluoro(oxalato)borate (LiDFOB) additive. The induction of direct defluorination of DFEC step by LiDFOB, as opposed to the breaking of C-O bonds without LiDFOB addition, is crucial in ensuring the exclusive formation of LiF-dominated SEI and maintaining the cyclic structure of DFEC. The defluorinated DFEC easily polymerizes to form poly(vinylene carbonate), enhancing the elasticity of the SEI. The resulting LiF-dominated SEI film with a polymer interwoven outer layer shows enhanced ionic conductivity and mechanical stability, which can effectively accelerate electrode reaction kinetics and maintain the structural stability of the Si electrode. As a result, the Si electrode with the electrolyte containing the designed dual-additive exhibits superior cycling stability and excellent rate performance, delivering a high reversible capacity of 1487.3 mAh g-1 after 1000 cycles at 2 A g-1.

A Solar and Seawater Co‐Involved Durable Rechargeable Battery Enabled by Crown Ether‐Rich Polymer‐Mediated Photoelectrodes

AbstractThe first flow‐type solar and seawater co‐mediated sodium‐air rechargeable battery (SSRB) for efficient solar‐to‐electrochemical energy conversion/storage is established. Such SSRB is enabled by a robust self‐regulated CEP/ZnWO4/WO3 heterojunction photoelectrochemical electrodes (PE) by passivating predesigned crown ether‐rich photoresponsive covalent organic polymer (CEP) layers onto ZnWO4‐modified WO3 nanosheet arrays. The PE design utilizes the previously‐unexplored self‐mediated effect of CEP to endow PE with superior stability, facilitated electrode reaction kinetics, and high efficiency of spatial charge separation simultaneously. This leads to remarkable light‐enhanced oxygen evolution catalysis with impressive photocurrent density up to 6.1 mA cm−2 at 1.23 V versus RHE in seawater – surpassing metal‐oxide‐based PEs ever reported for seawater splitting. Thus, the SSRB breaks the limit of the equilibrium voltage (3.47 V) of conventional seawater sodium‐air cells to deliver a low charge voltage of 2.71 V along with stable photo‐charge over 100 h and good photo‐charge/normal discharge cycling stability over 240 h – superior to almost all existing light‐involved air batteries. Combined experimental and modeling studies for the first time unveil the multi‐regulation effects of CEP passivation which prevents detrimental Cl‐corrosion, and promote oxygen evolution kinetics.

Challenge and Design Strategies of Polymer Organic Electrodes for Lithium‐Ion Batteries

AbstractDue to the scarcity of metallic lithium and the limited specific energy density of traditional inorganic cathodes, the application of lithium‐ion batteries (LIBs) in the large‐scale energy storage market is severely limited. To meet the growing power demands of electric vehicles and electronics, low‐cost and sustainable battery technologies need to be developed. Organic batteries and organic electrode materials emerge at a historic moment and show great potential. Polymer organic materials (POEs) with longer cycle life than small organic molecules that are easily soluble in liquid electrolytes provide more opportunities for advanced electrode materials. However, many issues remain to be addressed before POEs are widely used, such as sluggish electrode reaction kinetics and poor electronic conductivity. Herein, the classification, energy storage mechanism and features of POEs are briefly summarized. Further, the existing problems and design strategies of POEs are discussed and summarized in depth. This review aims to highlight the potential role of structural and morphological design in improving the practical performance of POEs in LIBs and provides insights into the in‐depth understanding and development of organic batteries and organic electrode materials.

Recent Advances in Graphene-Based Materials for Zinc-Ion Batteries.

Zinc-ion batteries (ZIBs) are a promising alternative for large-scale energy storage due to their advantages of environmental protection, low cost, and intrinsic safety. However, the utilization of their full potential is still hindered by the sluggish electrode reaction kinetics, poor structural stability, severe Zn dendrite growth, and narrow electrochemical stability window of the whole battery. Graphene-based materials with excellent physicochemical properties hold great promise for addressing the above challenges foe ZIBs. In this review, the energy storage mechanisms and challenges faced by ZIBs are first discussed. Key issues and recent progress in design strategies for graphene-based materials in optimizing the electrochemical performance of ZIBs (anode, cathode, electrolyte, separator and current collector) are then discussed. Finally, some potential challenges and future research directions of graphene-based materials in high-performance ZIBs are proposed for practical applications.

Recent progress of antipoisoning catalytic materials for high temperature proton exchange membrane fuel cells doped with phosphoric acid

The current challenges and opportunities faced by HT-PEMFCs are discussed, as well as possible future solutions. This review can provide guidance for the future development of high-performance HT-PEMFC catalysts.

Advancements and prospects of perovskite-based fuel electrodes in solid oxide cells for CO2 electrolysis to CO.

Carbon dioxide (CO2) electrolysis to carbon monoxide (CO) is a very promising strategy for economically converting CO2, with high-temperature solid oxide electrolysis cells (SOECs) being regarded as the most suitable technology due to their high electrode reaction kinetics and nearly 100% faradaic efficiency, while their practical application is highly dependent on the performance of their fuel electrode (cathode), which significantly determines the cell activity, selectivity, and durability. In this review, we provide a timely overview of the recent progress in the understanding and development of fuel electrodes, predominantly based on perovskite oxides, for CO2 electrochemical reduction to CO (CO2RR) in SOECs. Initially, the current understanding of the reaction mechanisms over the perovskite electrocatalyst for CO synthesis from CO2 electrolysis in SOECs is provided. Subsequently, the recent experimental advances in fuel electrodes are summarized, with importance placed on perovskite oxides and their modification, including bulk doping with multiple elements to introduce high entropy effects, various methods for realizing surface nanoparticles or even single atom catalyst modification, and nanocompositing. Additionally, the recent progress in numerical modeling-assisted fast screening of perovskite electrocatalysts for high-temperature CO2RR is summarized, and the advanced characterization techniques for an in-depth understanding of the related fundamentals for the CO2RR over perovskite oxides are also reviewed. The recent pro-industrial application trials of the CO2RR in SOECs are also briefly discussed. Finally, the future prospects and challenges of SOEC cathodes for the CO2RR are suggested.

A Scalable and Effective Strategy for Boosting the Initial Coulombic Efficiency of Silicon Suboxide Anode

Silicon suboxide (SiO x ) is one of the most attractive candidates for anode materials for high-energy-density lithium-ion batteries due to its high specific capacity and its relatively lower volume expansion than that of Si. However, its low initial Coulombic efficiency (ICE) seriously affects its practical applications. In this work, we demonstrate a scalable and effective strategy to enable a high ICE of the SiO x electrode through a MnO-assisted disproportionation reaction. The obtained Mn 2 SiO 4 –Si–SiO x @C (MSS@C) material shows a reduced lithium irreversible consumption in the first cycle. The Mn 2 SiO 4 phase can store lithium through a conversion reaction with a smaller volume change (33%) than SiO x , which helps to maintain the structural stability of MSS@C during cycling. Meanwhile, the metallic Mn nanoparticles generated from Mn 2 SiO 4 during the lithiation process facilitate electron conduction, thus improving the electrode reaction kinetics. Owing to the synergetic effects, the MSS@C material exhibits a higher ICE (79.51%) compared to 60.91% of pure SiO x , and a superior cyclic performance (832 mAh g −1 at 0.5 A g −1 after 350 cycles with a capacity retention of 90.4%). This work offers a new approach to increase the ICE while improving the electrode reaction kinetics and cycling stability of SiO x -based materials.

Atomizing platinum for hydrogen electrode reactions

Anion exchange membrane fuel cells and water electrolyzers are promising hydrogen energy conversion devices due to more abundant options toward catalysts under alkaline conditions. However, the sluggish hydrogen electrode reaction kinetics remains a major challenge for wide applications. Herein, we conceive atomically dispersed Pt on Ni single-atom/nitrogen-doped carbon (PtA/C-Ni-NC), in which the Pt co-exists in Pt single atoms (PtA-N4 sites) and atomically dispersed Pt clusters (PtC). Such a multi-atom scale PtA/C-Ni-NC structure greatly enhances the active site density and atomic utilization by balancing hydrogen adsorption energy and hydroxyl adsorption energy, leading to significantly elevated hydrogen oxidation and evolution reactions (HOR/HER) catalysis activity. For HOR, it reaches a current density of 3.75 mA cm−2 at a potential of 200 mV, with a mass activity of 72.3 mA mg−1, which is 3 times higher than that of commercial Pt/C. For HER, to deliver the current density of 10 mA cm−2, the overpotential is only 10 mV, with a mass activity of 2217.7 mA mg−1, which is 8.4 times higher than that of commercial Pt/C. Density functional theory (DFT) calculations and in-situ detection results further confirm that the equilibrium between hydrogen binding energy (HBE) and hydroxyl binding energy (OHBE), and the unique interfacial water on the catalyst surface are responsible for high activity of the catalyst. This work provides important insights into developing multi-atom scale catalysts for efficient hydrogen electrode reactions and deeper understanding active sites dispersed at the atomic level.

Use of Surface Features with Controlled Kinetics to Verify Fits of Scanning Electrochemical Microscopy Images

Scanning Electrochemical Microscopy (SECM) is a promising technique for measuring kinetics of redox reactions at surfaces. The conversion of the current map - produced by rastering an electrode over the surface - to a maps of the rate constant of reactions at the surface requires computer modelling and statistical techniques. Experimentally obtained SECM images are necessary to validate computer models that will be used to test these fitting procedures.The largest challenge was finding or creating samples that have reactive sites of known kinetics that were sufficiently slow to be activation-limited. This was achieved by producing small precious metal electrodes embedded in an insulating surface. The exchange currents of these electrodes were characterized using cyclic voltammetry at high scan rates[1,2] so that the rate constant of the electrodes could be effectively controlled by the potential at which they were poised. SECM images of these electrodes can compared to computer simulations to verify that they produced correct results. [1] Nicholson, R.S. Theory and Application of Cyclic Voltammetry for Measurement of Electrode Reaction Kinetics. Anal. Chem. 1965, 37, 11, 1351–1355[2] Mirkin, M.V.; Bard, A.J. Simple Analysis of Quasi-Reversible Steady-State Voltammograms. Anal. Chem. 1992, 64, 19, 2293–2302

Co/Mn ratio-regulated hexacyanoferrates as a long-life and high-rate cathode for aqueous Zn-ion batteries

Among all kinds of cathodes for aqueous Zn-ion batteries, Mn-based hexacyanoferrates exhibit advantages of high-voltage and abundant resources. However, they suffer from inferior cycle-life and rate capability, which may be attributed to the structural instability and metal ion dissolution. In this work, a continuous element substitution (Mn replaced by Co) is employed to modify the electrochemical performance of Mn-based hexacyanoferrates. With the increasing ration of Co/Mn, the Mn, Co-based hexacyanoferrate (MnCoHCF) samples show unchanged crystalline phase with similar morphology and increasing Co dopant. Additionally, the initial specific capacity gradually decreases, but the electrochemical polarization is alleviated. Among the samples, MnCoHCF-4 (ratio of Co/Mn of 3:1) exhibits excellent cycling life (71.4% after 3000 cycles at 5 C) and rate performance (81.4 mA h g−1 at 10 C). In-situ techniques reveal the obvious metal ion dissolution with a low ratio of Co/Mn during the electrochemical process, resulting in poor structure stability and reaction kinetics of MnHCF electrode. However, When the ratio of Co/Mn is increased, the metal ion dissolution is effectively suppressed, and the MnCoHCF electrode shows improved structure stability and reaction kinetics. This work proposes an effective modification for hexacyanoferrates and other high-voltage Prussian blue analogues, which may promote the application of aqueous Zn-ion batteries.

Graphene quantum dots-decorated N-doped Bi2MoO6 hollow nanostructures: Coupling defect engineering with interface engineering toward enhanced charge storage for supercapacitors

The practical applications of transition-metal oxides as electrode materials for supercapacitors are still impeded by their intrinsically poor electrical conductivity and limited number of electroactive sites. Herein, a defect engineering strategy combined with interface engineering is adopted to create nitrogen-doped bismuth molybdate (N-BMO) hollow nanostructures decorated with graphene quantum dots (GQDs). Theoretical calculation and experimental results indicate that the N doping in BMO can enhance electrical conductivity of N-BMO by reducing its electronic band gap. Moreover, the surface decoration of GQDs on N-BMO enables higher electrical conductivity and more electroactive sites. More importantly, a built-in electric field is formed at the N-BMO/GQD interface due to their Fermi-level difference, which favors fast interfacial charge transfer and accelerate electrode reaction kinetics. Accordingly, the optimized N-BMO@GQD electrodes yield higher specific capacities (572 and 435 C g−1 at 1 and 10 A g−1, respectively) and better cycling stability (91 % capacity retention after 10000 cycles at 5 A g−1) compared to pristine BMO electrode. Moreover, an assembled asymmetric supercapacitor device with N-BMO@GQD as positive electrode can deliver an energy density of 45.2 Wh kg−1 at 801 W kg−1. This study showcases an efficient strategy to design and develop promising BMO-based electrode materials for supercapacitors.

Hierarchical Architecture Engineering of Branch-Leaf-Shaped Cobalt Phosphosulfide Quantum Dots: Enabling Multi-Dimensional Ion-Transport Channels for High-Efficiency Sodium Storage.

New-fashioned electrode hosts for sodium-ion batteries (SIBs) are elaborately engineered to involve multifunctional active components that can synergistically conquer the critical issues of severe volume deformation and sluggish reaction kinetics of electrodes toward immensely enhanced battery performance. Herein, it is first reported that single-phase CoPS, a new metal phosphosulfide for SIBs, in the form of quantum dots, is successfully introduced into a leaf-shaped conductive carbon nanosheet, which can be further in situ anchored on a 3D interconnected branch-like N-doped carbon nanofiber (N-CNF) to construct a hierarchical branch-leaf-shaped CoPS@C@N-CNF architecture. Both double carbon decorations and ultrafine crystal of the CoPS in-this exquisite architecture hold many significant superiorities, such as favorable train-relaxation, fast interfacial ion-migration, multi-directional migration pathways, and sufficiently exposed Na+ -storage sites. In consequence, the CoPS@C@N-CNF affords remarkable long-cycle durability over 10000 cycles at 20.0Ag-1 and superior rate capability. Meanwhile, the CoPS@C@N-CNF-based sodium-ion full cell renders the potential proof-of-feasibility for practical applications in consideration of its high durability over a long-term cyclic lifespan with remarkable reversible capacity. Moreover, the phase transformation mechanism of the CoPS@C@N-CNF and fundamental springhead of the enhanced performance are disclosed by in situ X-ray diffraction, ex situ high-resolution TEM, and theoretical calculations.

Recent Advancements in Electrochemical Hydrogen Production via Hybrid Water Splitting.

As one of the most promising approaches to producing high-purity hydrogen (H2 ), electrochemical water splitting powered by the renewable energy sources such as solar, wind, and hydroelectric power has attracted considerable interest over the past decade. However, the water electrolysis process is seriously hampered by the sluggish electrode reaction kinetics, especially the four-electron oxygen evolution reaction at the anode side, which induces a high reaction overpotential. Currently, the emerging hybrid electrochemical water splitting strategy is proposed by integrating thermodynamically favorable electro-oxidation reactions with hydrogen evolution reaction at the cathode, providing a new opportunity for energy-efficient H2 production. To achieve highly efficient and cost-effective hybrid water splitting toward large-scale practical H2 production, much work has been continuously done to exploit the alternative anodic oxidation reactions and cutting-edge electrocatalysts. This review will focus on recent developments on electrochemical H2 production coupled with alternative oxidation reactions, including the choice of anodic substrates, the investigation on electrocatalytic materials, and the deep understanding of the underlying reaction mechanisms. Finally, some insights into the scientific challenges now standing in the way of future advancement of the hybrid water electrolysis technique are shared, in the hope of inspiring further innovative efforts in this rapidly growing field.

Recent Progress of Vertical Graphene: Preparation, Structure Engineering, and Emerging Energy Applications.

Vertical graphene (VG) nanosheets have garnered significant attention in the field of electrochemical energy applications, such as supercapacitors, electro-catalysis, and metal-ion batteries. The distinctive structures of VG, including vertically oriented morphology, exposed, and extended edges, and separated few-layer graphene nanosheets, have endowed VG with superior electrode reaction kinetics and mass/electron transportation compared to other graphene-based nanostructures. Therefore, gaining insight into the structure-activity relationship of VG and VG-based materials is crucial for enhancing device performance and expanding their applications in the energy field. In this review, the authors first summarize the fabrication methods of VG structures, including solution-based, and vacuum-based techniques. The study then focuses on structural modulations through plasma-enhanced chemical vapor deposition (PECVD) to tailor defects and morphology, aiming to obtain desirable architectures. Additionally, a comprehensive overview of the applications of VG and VG-based hybrids d in the energy field is provided, considering the arrangement and optimization of their structures. Finally, the challenges and future prospects of VG-based energy-related applications are discussed.

Synergized N and P co-doped Ti3C2Tx mxene enabling high-performance Li-air batteries

Lithium-oxygen batteries (LOBs) with a theoretical energy density of up to 3500 Wh kg−1 hold a promise for the next-generation high-energy-density batteries. However, the slow oxygen reduction/evolution kinetics at the cathode limits the performance of Li-air batteries. The rational design of efficient catalysts is essential for the improvement of oxygen electrode reaction kinetics. Herein, we report a facile strategy to co-dope N and P atoms simultaneously into Ti3C2Tx (NP-Ti3C2Tx) MXene via an electrostatic self-assembly approach. The co-doped NP-Ti3C2Tx layers expose abundant active sites, providing more space for accommodating the formed Li2O2. Moreover, the N and P co-doping facilitates efficient electron transport in Ti3C2Tx MXene. The LOB with NP-Ti3C2TX catalyst delivers a high discharge capacity of 24,940 mAh/g at 1000 mA g−1. At a cut-off capacity of 1000 mAh/g, this battery runs continuously for 159, 276, 185, and 229 cycles at current densities of 1000, 2000, 3000, and 5000 mA g−1, respectively. Theoretical calculations unveil that N and P co-doping enables lower ηORR and ηOER of only 0.26 V and 0.13 V on Ti3C2Tx MXene, respectively. This work offers a feasible approach for constructing efficient MXene electrocatalysts for Li–air batteries.

Evaluation of mitigation of capacity decay in vanadium redox flow batteries for cation- and anion-exchange membrane by validated mathematical modelling

Vanadium redox flow battery (VRFB) is a potential electrochemical energy storage solution for residential accumulation and grid stabilization. Long-term durability, non-flammability and high overall efficiency represent the main advantages of the technology. The ion-exchange membrane, an essential component of the battery stack, is largely responsible for the efficiency of the battery and capacity losses caused by asymmetric cross-over of vanadium ions and a solvent.To mitigate these losses, we developed a mathematical model of the VRFB single-cell for both cation-exchange membrane (CEM) and anion-exchange membrane (AEM) and validated it against our own experimental data. Our model simulates the charge-discharge cycling of a VRFB single-cell under selected sets of operating conditions differing in the following parameters: applied current density, initial volume and concentration of electrolytes, arrangement of storage tanks (hydraulic shunt) and option of periodic rebalancing of electrolytes. The model includes a description of vanadium ions permeation and osmotic flux across the membrane and kinetics of electrode reactions. The hydraulic connection of electrolyte tanks appears to be the most promising mitigating strategy, reducing capacity losses by 69 % over 150 cycles when compared to standard VRFB set-up, which we have also confirmed experimentally. Moreover, by combining the operation methods, our model shows that using AEM with the hydraulic electrolyte connection and periodic rebalancing, the overall battery utilization can be increased by 80 % compared to a standard operation of VRFB using CEM. The developed model offers useful optimization tool for the construction and operation of flow batteries and can be easily adapted for other chemistries.

Regulating d-orbital electronic configuration of Ni-based chalcogenides to enhance the oxygen electrode reactions in Li-O2 batteries

Transition metal chalcogenides based electrocatalysts with regulable d-orbital electronic configuration by various chalcogen anions can exhibit excellent oxygen electrode reaction kinetics in Li-O2 batteries (LOBs). In this work, an electron rearrangement strategy to improve the catalytic activity of hexagonal NiS microsheets for LOBs has been developed via introducing Se anion as a substitution of S. With the as-prepared NiS0.67Se0.33 as cathode catalyst, LOB could achieve evidently lower overpotentials, larger discharge capacity, and ultralong cycling life than that using NiS. With the help of physicochemical techniques and theoretical calculations, the performance enhancement of NiS0.67Se0.33 could be elucidated with its suitable d-orbital electronic configuration. Specifically, Se anion substitution can modulate metal–chalcogen interactions with increased charge density and positively shifted d-band center of Ni metal cation, thereby promoting the d-p orbitals hybridization with increased binding strength to LiO2 intermediates and promoting oxygen reduction/evolution reaction kinetics. Moreover, small amount of Ni dissolution from NiS0.67Se0.33 to the electrolyte because of the rearranged electronic configuration also contributes to the enhanced oxygen electrochemistry and improved LOB performance by serving as a redox mediate catalyst. This work provides a facile anion doping engineering to facilitate the oxygen electrode reactions in LOBs by modulating d-orbital electronic configuration.

Free-standing TiNb6O17/rGO composites as a superior anode host for high-performance Li-ion capacitor

Li-ion capacitors are very enticing power sources having high energy and power density as they exemplify the benefits of both Lithium-ion battery (LIB) and supercapacitors (SCs) together. However, the high performance of LIC is limited due to low specific capacity and slow reaction kinetics of electrodes. Herein, pseudo-capacitive titanium niobium oxide (TiNb6O17: TNO) and reduced graphene oxide (rGO) composite material was fabricated and investigated as a unique anode material for LIC. The application of TNO-rGO composite electrode (R-TNO) as insertion anode material in LIC has been investigated due to its excellent electrochemical performance, intrinsic fast pseudo-capacitive behavior along with good reversibility and cyclability. A novel LIC was fabricated using R-TNO electrode as an innovative insertion type anode and activated carbon (AC) as cathode for the first time. Compared to conventional method (with binder), here the electrodes are prepared using binder-free and current-collector tape casting method to further enhance the energy and power density. As a result, the flexible and free-standing electrodes were acquired and used as anode for flexible LIC application. Comprehensive electrochemical analysis elucidates the improved storage behavior of composite electrode with rapid reaction kinetics, high reversibility and excellent cyclic stability. Novel R-TNO/AC LIC exhibited maximum energy density of 142.10 Wh/kg and power density of 18.75 kW/kg. The LIC device illustrated 88% cyclic stability even after 10,000 cycles, confirming its good electrochemical stability during electrochemical process. The extraordinary performance of LIC device is ascribed to collective effect of pseudo-capacitive behavior of TiNb6O17 particles and the buffering effect provided by rGO sheets. The results obtained are encouraging and propose the utilization of fabricated intercalation anode materials for the development of safe and high performance LICs.

Identifiability of the mechanisms governing the reaction kinetics of MIEC electrodes in solid oxide cells

The oxygen reduction reaction (ORR) is the main phenomenon occurring in mixed ionic and electronic conductors (MIECs) used as air electrodes in solid oxide cells. Their optimisation requires the identification of the ORR regime, which is typically performed via electrochemical impedance spectroscopy (EIS). In this study we present a physics-based model to simulate the impedance spectra of p-type oxygen-deficient perovskite MIEC materials. The EIS response of four extreme kinetic scenarios, characterised by the rate-determining step (electron-transfer or ion-transfer) and the high/low surface coverage of adsorbed oxygen, is mechanistically interpreted for both dense films and porous electrodes. A strategy for kinetic identification is proposed based on distinctive EIS fingerprints at different oxygen partial pressures (pO2) and cathodic bias. However, distinguishing the kinetic scenarios is not free from ambiguity even in dense films since some scenarios are discriminated only via a quantitative analysis, which may be susceptible to experimental errors in real measurements, and reverse behaviours appear when combining cathodic bias with pO2 variation. More difficulties arise in porous electrodes since bulk oxygen vacancy transport interacts with the ORR response. Application of the proposed strategy using literature data for some common MIEC materials shows the typical challenges of kinetic identification when relying solely on EIS.

Double-shelled NiS/SnS@N-doped carbon nanoboxes engineered from NiSn(OH)6 cube templates for advanced sodium-ion battery anodes

Overcoming the sluggish reaction kinetics and volume effects of metal sulfides as anodic materials for sodium-ion batteries remains a challenging task. In this study, a multistep template-engaged strategy is employed for the first time to fabricate hierarchical double-shells NiS/SnS@nitrogen doped carbon (NiS/SnS@NC) nanoboxes, utilizing NiSn(OH)6 cubes as starting templates. The synergistic combination of sophisticated sulfide components and the double-shell structure effectively mitigates volume variation, reduces nanoparticle cohesion, and enhances electrode reaction kinetics. Notably, NiS/SnS@NC exhibits outstanding stability under high current density while maintaining a high capacity. Comprehensive kinetics analysis reveals that the enhanced sodium storage of NiS/SnS@NC can be attributed to its low interface reaction resistance, significant capacitive contribution, and rapid mass-transfer kinetics. The stepwise (de)sodiation processes of the NiS/SnS@NC anode are elucidated through various in/ex-situ characterization techniques, confirming the alternating reaction activity alternations between two components, which acts as a self-buffering and self-conductivity mechanism to enhance sodium storage. Finally, a practical application is demonstrated, where a well-designed NiS/SnS@NC||Na3V2(PO4)2F3/C full cell shows promising performance, achieving a high capacity of 265 mAh/g after 1000 cycles at 2.0 A/g. This work′s synthesis strategy and research findings contribute to advancing the exploration and application of NiSn(OH)6 and its derivatives in the field of energy storage and beyond.