Transition Metal Selenides Research Articles

High-entropy selenides derived from Prussian blue analogues as electrode materials for sodium-ion batteries

Transition metal selenides (TMS) have received much attention as anode materials for sodium-ion batteries (SIBs) because of their high theoretical capacity and excellent redox reversibility. However, their further development is constrained by the dissolution of transition metal ions and substantial volume changes experienced during cycling. Herein, the high-entropy Prussian blue analogues were selenized by the vapor infiltration method, resulting in the formation of a core–shell structured high-entropy selenides (HESe-6). The core–shell structure with voids and abundant selenium vacancies on the surface effectively mitigates bulk expansion and enhances electronic conductivity. Furthermore, the high-entropy property endows an ultra-stable crystal structure and inhibits the dissolution of metal ions. The ex-situ EIS and in-situ XRD results show that HESe-6 is able to be reversibly transformed into highly conductive ultrafine metal particles upon Na+ embedding, providing more Na+ reactive active sites. In addition, despite the incorporation of up to seven different elements, it exhibits minimal phase transitions during discharge/charge cycles, effectively mitigating stress accumulation. HESe-6 could retain an ultralong-term stability of 765.83 mAh g−1 after 1000 loops even at 1 A g−1. Furthermore, when coupled with the Na3V2(PO4)2O2F cathode, it maintains a satisfactory charge energy density of 303 Wh kg−1 after 300 cycles, which shows promising application prospect in the future.

Transition Metal Selenide-Based Anodes for Advanced Sodium-Ion Batteries: Electronic Structure Manipulation and Heterojunction Construction Aspect.

In recent years, sodium-ion batteries (SIBs) have gained a foothold in specific applications related to lithium-ion batteries, thanks to continuous breakthroughs and innovations in materials by researchers. Commercial graphite anodes suffer from small interlayer spacing (0.334 nm), limited specific capacity (200 mAh g-1), and low discharge voltage (<0.1 V), making them inefficient for high-performance operation in SIBs. Hence, the current research focus is on seeking negative electrode materials that are compatible with the operation of SIBs. Many studies have been reported on the modification of transition metal selenides as anodes in SIBs, mainly targeting the issue of poor cycling life attributed to the volume expansion of the material during sodium-ion extraction and insertion processes. However, the intrinsic electronic structure of transition metal selenides also influences electron transport and sodium-ion diffusion. Therefore, modulating their electronic structure can fundamentally improve the electron affinity of transition metal selenides, thereby enhancing their rate performance in SIBs. This work provides a comprehensive review of recent strategies focusing on the modulation of electronic structures and the construction of heterogeneous structures for transition metal selenides. These strategies effectively enhance their performance metrics as electrodes in SIBs, including fast charging, stability, and first-cycle coulombic efficiency, thereby facilitating the development of high-performance SIBs.

Rational design of a setaria-like NiTe2/MoS2 semi-coherent heterogeneous interface for enhancing diffusion kinetics in potassium-ion batteries

Constructing unique heterostructures is a highly effective approach for enhancing the K+ storage capability of transition metal selenides. Such structures generate internal electric fields that significantly reduce the charge transfer activation energy. However, achieving a flawless interfacial region that maintains the optimal energy level gradient and degree of lattice matching remains a considerable challenge. In this study, we synthesised Setaria-like NiTe2/MoS2@C heterogeneous interfaces at which three-dimensional MoS2 nanosheets are evenly embedded in NiTe2 nanorods to form stabilised heterojunctions. The NiTe2/MoS2 heterojunctions display distinctive electronic configurations and several active sites owing to their low lattice misfits (δ = 13 %), strong electric fields, and uniform carbon shells. A NiTe2/MoS2@C anode in a potassium-ion battery (KIB) exhibited an impressive reversible capacity of 125.8 mAh/g after 1000 cycles at a rate of 500 mA g−1 and a stable reversible capacity of 111.7 mAh/g even after 3000 cycles at 1000 mA g−1. Even the NiTe2/MoS2@C//perylene tetracarboxylic dianhydride full battery configuration maintained a significant reversible capacity of 92.4 mAh/g after 100 cycles at 200 mA g−1, highlighting its considerable potential for application in KIBs. Calculations further revealed that the well-designed NiTe2/MoS2 heterojunction significantly promotes K+ ion diffusion.

Intercalation-Induced Localized Conversion Reaction in h-CuSe for Ultrafast-Rechargeable and Long-Cycling Sodium Metal Battery.

Cathode materials of sodium-based batteries with high specific capacity and fast charge-discharge mode, as well as ultralong reversible cycles at wide applied temperatures, are essential for future development of advanced energy storage system. Developing transition metal selenides with intercalation features provides a new strategy for realizing the above cathode materials. Herein, this work reports a storage mechanism of sodium ion in hexagonal CuSe (h-CuSe) based on the density functional theory (DFT) guidance. This work reveals that the two-dimensional ion intercalation triggers localized redox reaction in the h-CuSe bulk phase, termed intercalation-induced localized conversion (ILC) mechanism, to stabilize the sodium storage structure by forming localized Cu7Se4 transition phase and adjusting the near-edge coordination state of the Cu sites to achieve high reversible capacity and ultra-long cycling life, while allowing rapid charge-discharge cycling over a wide temperature range.

Heterostructure CoSe2/Sb2Se3 nanocrystals embedded into nanocage-in-nanofiber carbon framework for ultralong-life sodium-ion batteries

Transition metal selenides are considered as one of the most promising anode materials for sodium-ion batteries (SIBs) on account of their high theoretical specific capacity. However, the poor conductivity, sluggish kinetics and volume expansion during the (de)sodiation process hinder its application. Herein, a novel heterostructure of CoSe2/Sb2Se3 nanocrystals embedded into nanocage-in-nanofiber carbon framework is designed and constructed via electrospinning, carbonization, ion exchange and selenization processes. In this structure, bimetallic selenide heterostructure accelerates electron/ion transfer kinetics and Na+ adsorption capacity, carbon nanocages structure alleviates the volume expansion and maintains structural integrity during the (de)sodiation process, and carbon nanofibers connect the nanocages in series to shorten the electron transmission path and enhance electrical conductivity. As a self-supporting anode for SIBs, as-synthesized CoSe2/Sb2Se3@C@CNF shows a high reversible capacity of 406 mAh g-1 at 0.2 A g-1 after 200 cycles and displays excellent rate capability. More remarkably, the CoSe2/Sb2Se3@C@CNF anode manifests an outstanding cycling stability for over 2000 and 12,000 cycles at 1 and 5 A g-1, with the capacity retention being 97 % and 103 % respectively. Meanwhile, the excellent sodium storage performance is revealed by kinetic analysis, energy level analysis and density functional theory calculations.

Coupling the fast electron transportation of cobalt diselenide-based anode via cationic modulation for high rate Na+ storage

The sodium-ion batteries (SIBs), as compelling candidate for partially replacing lithium-ion batteries (LIBs) in relevant application scenarios, is gaining increasing attention. The development of high-rate performance anode materials for sodium-ion batteries is exceptionally crucial. Here, a ZIF (zeolitic imidazolate framework) compound targeting bimetallic cations has applied through a pyrolysis-induced in-situ selenization strategy. This resulted in a nitrogen-doped porous carbon-encapsulated Fe-ion-modified CoSe2 material with a rhombic dodecahedron morphology (Fe-CoSe2@NC). The architecture not only effectively alleviates the bulk stress induced by the insertion/extraction of sodium ions, but also enhances the migration and transport of electrons/ions. Additionally, Fe doping enhances the material's conductivity and expedites reaction kinetics. Consequently, the Fe-CoSe2@NC exhibits outstanding rate performance and cycling stability (362.54 mAh g-1 after 1000 cycles at a current density of 10.0 A g-1) when utilized as an anode for SIBs in a coin-type half-cell. The Fe-CoSe2@NC also delivers a high initial coulombic efficiency (ICE) of 70.14%. This is substantiated by diffusion analysis and in-situ electrochemical impedance spectroscopy (EIS) characterization. The charging and discharging mechanisms of Fe-CoSe2@NC were verified through XRD and TEM characterizations during the electrochemical processes. When coupled with Na3V2(PO4)3 as the cathode material to form a full cell, the Fe-CoSe2@NC// Na3V2(PO4)3 battery system achieves a high energy density of 112.05 Wh kg-1. In this study, the successful construction of a transition metal selenide anode material for SIBs characterized by a stable structure and facilitation of rapid ion migration was demonstrated.

A facile synthesis of novel binder-free NiSe-SnSe electrode: With enhanced electrochemical performance and superior life span

Fossil fuels depletion and deteriorating environmental conditions have deepened the growing demand for new energy solution. The bimetallic transition metal selenides, which a smaller bandgap and greater electrical conductivity than nanometals, are the subject of recent research on hybrid supercapacitors, composite systems integrating battery-like energy storage capability with capacitive charging. Herein, a new binder NiSe-SnSe composite system for supercapacitors has been developed through facile hydrothermal method, and its structural features, morphological characteristics as well as electrochemical properties are systematically studies in this work. Additionally, a thorough understanding of the electrode physicochemical properties are presented. Practically, a NiSe-SnSe||AC|KOH ASC had excellent specific capacitance (618 F/g at 1 A g−1), mainly owing to fast charge transport in electrochemical action. More importantly, the NiSe-SnSe||AC|KOH ASC electrode exhibits a high specific power of 8400 W kg−1 at a high specific energy of 55.4 Wh kg−1 with remarkable cycling stability by 96.4 % maintenance of initial capacitance after 5500 cycles. Our findings provide a profound understanding and possible use of this newly developed asymmetric supercapacitor in energy storage.

Integrated graphene-based semimetal/metallic-like MSe2 (M = Pt, Re) heterostructures for mid-infrared ultrafast photonics

Mid-infrared (MIR) ultrafast photonics has received significant interest due to the development of compact and robust MIR laser sources capable of emitting wavelengths beyond 2 μm. Transition metal selenides (TMSes), with the properties of feasibly tunable bandgaps, desirable photocarrier transmission property, and broadband nonlinear optical response, have become a research focus on ultrafast photonic applications. However, the relatively large bandgap (around 1 eV) of the TMSes greatly restricts their applications in the MIR region. Here, the synergetic interaction between multilayer graphene (Gr) and semimetal or metallic-like (PtSe2 and ReSe2) is employed to tune the optical properties and to further optimize the optical performance of TMSes in the MIR region. Benefiting from the ultrafast photocarrier relaxation time, appropriate modulation depth, and almost zero non-saturated loss of Gr-PtSe2 and Gr-ReSe2 heterostructures, stable Q-switched laser operation at 1.9 μm has been achieved in an integrated design based on waveguide laser platform. The results demonstrate that combining the semimetal or metallic-like TMSes with van der Waals (vdW) heterostructures is a promising strategy to extend the photonic applications of TMSes into the MIR region, indicating the potential applications of graphene-based TMSes vdW heterostructures for MIR integrated photonics.

Microwave-Assisted Synthesis of Few-Layer Ti3C2Tx Loaded with Ni0.5Co0.5Se2 Nanospheres for High-Performance Supercapacitors.

Transition metal selenides have high theoretical capacities, making them attractive candidates for energy storage applications. Here, using the microwave-absorbing properties of the materials, we designed a simple and efficient microwave-assisted synthesis method to produce a composite made of nanospheres Ni0.5Co0.5Se2 (NCSe) and highly conductive, stable Ti3C2Tx MXene. The Ni0.5Co0.5Se2/Ti3C2Tx composites are characterized via scanning electron microscopy, X-ray diffraction, cyclic voltammetry, and electrochemical impedance spectroscopy. The findings indicate that 3D Ni0.5Co0.5Se2 bimetallic selenide nanospheres were uniformly loaded within the few-layer Ti3C2Tx MXene wrapper in a short period. The optimal NCSe/Ti3C2Tx-2 electrode can demonstrate a specific capacitance of 752.4 F g-1 at 1 A g-1. Furthermore, the asymmetric supercapacitor combined with activated carbon maintains a capacitance retention of 110% even after 5000 cycles. The method of directly growing active substances on few-layer Ti3C2Tx MXene will provide inspiration for the manufacture of high-pseudocapacitance supercapacitors.

Incorporating ZIF-8-derived ZnSe into hollow carbon nanospheres as anodes for lithium-ion batteries

Transition metal selenides (TMSs) show great potential as anode materials for lithium-ion batteries (LIBs), boasting a high theoretical capacity. Nevertheless, their practical utility faces challenges, mainly stemming from significant volume changes that lead to rapid capacity decay during charge and discharge cycles. To overcome this challenge, we present a systematic approach involving the growth of uniformly dispersed ultrafine ZnSe nanoparticles derived from ZIF-8 on the surface of hollow carbon nanospheres (ZnSe@N-HCS/700). When utilized as an anode material for LIBs, the ZnSe@N-HCS/700 electrode demonstrates exceptional electrochemical performance. Specifically, it achieves a capacity of 1299 mAh g−1 after 100 cycles at a current density of 100 mA g−1 and maintains a capacity of 614 mAh g−1 even after 1800 cycles at 2500 mA g−1. The hollow structure of the composite alleviates the volume variation of ZnSe nanoparticles during charge and discharge processes, and provides a large reactive surface area, thereby significantly enhancing lithium storage capacity. In conclusion, our strategy presents an innovative approach to synthesize negative electrode materials with unique structures for LIBs.

Phase-controllable synthesis of nickel selenide nanostructures decorated on carbon nanotubes as efficient binder-free cathodes for hybrid supercapacitors

In this work, we employed a facile pulse-reversal (PR) electrodeposition route to successfully synthesize nickel selenide nanostructures directly decorated on carbon nanotubes (CNTs) by adjusting different pulse-reversal potentials. The study systematically investigated the effects of PR potential on the morphology and composition of nickel selenides on CNTs. The experimental results suggested that regulating the PR potential could effectively manage the formation of nickel selenide nanostructures on the backbones of CNTs. By decreasing the PR potential from 0.2 to −0.2 V, the composition of nickel selenide nanostructures changed from NiSe2 to Ni0.85Se. The CNTs@NiSe2 electrode outperformed the others with a specific capacity of 125.4 mAh g−1 at 2 A g−1 and an impressive capacity retention of 81.2 % at 16 A g−1. The assembled hybrid supercapacitor using CNTs@NiSe2 as the cathode achieved exceptional performance with a high specific capacity of 42 mAh g−1 at 1 A g−1 and a maximum energy density of 33.6 Wh kg−1 at 800 W kg−1. This work presents an efficient approach that can be widely employed to fabricate one-dimensional carbon material-supported transition metal selenide nanostructures for practical applications in the next generation of energy storage and conversion.

Bimetallic Selenide CuFeSe2 as Mg‐Storage Material for Rechargeable Magnesium Batteries

AbstractRechargeable magnesium batteries (RMBs) are appealing alternatives for energy storage systems based on the high theoretical capacity, low price and high security of the Mg metal anode. Nevertheless, the shortage of high‐performance cathode materials severely obstructs its development. As an important conversion material, transition metal selenides, with desirable theoretical capacity and weak bond energy (Mg−Se), have attracted more attention in recent years. In this study, CuFeSe2 (CFS) nanoparticles were produced by a hydrothermal approach and its feasibility as a cathode material for RMBs was further investigated. Given the synergistic effect between Cu and Fe, the optimized CFS shows a reversible capacity of 120 mAh g−1 at 100 mA g−1, outstanding long‐term cyclability (86 mAh g−1 at 1 A g−1 after 600 cycles), and prominent rate capability (85 mAh g−1 at 1 A g−1). Density functional theory (DFT) computations conclude CFS exhibits a suitable migration barrier for Mg2+ along the tunnel of 0.92 eV. An in‐depth investigation of the mechanism demonstrates that the Mg storage process can be divided into solid solution reaction and the conversion processes by ex‐situ techniques. This work contributes to further investigate the Mg2+ storage mechanism of cathode materials for RMBs.

Facile construction of Cu2-xSe@C nanobelts as anode for superior sodium-ion storage

Transition metal selenides are considered promising electrochemical energy storage materials due to their excellent rate properties and high capacity based on multi-step conversion reactions. However, its practical applications are hampered by poor conductivity and large volume variation for Na+ storage, which resulting fast capacity decay. Herein, a facile metal-organic framework (MOF) derived method is explored to embed Cu2-xSe@C particles into a carbon nanobelts matrix. Such carbon encapsulated nanobelts' structural moderate integral electronic conductivity and maintained the structure from collapsing during Na+ insertion/extraction. Furthermore, the porous structure of these nanobelts endows enough void space to mitigate volume stress and provide more diffusion channels for Na+/electrons transporting. Due to the unique structure, these Cu2-xSe@C nanobelts achieved ultra-stable cycling performance (170.7 mAh/g at 1.0 A/g after 1000 cycles) and superior rate capability (94.6 mAh/g at 8 A/g) for sodium-ion batteries. The kinetic analysis reveals that these Cu2-xSe@C nanobelts with considerable pesoudecapactive contribution benefit the rapid sodiation/desodiation. This rational design strategy broadens an avenue for the development of metal selenide materials for energy storage devices.

High-entropy MnCoCuZnAlSe2 nanosheet arrays for highly efficient alkaline oxygen evolution reaction

The oxygen evolution reaction is the primary obstacle in the electrochemical breakdown of water; whereas transition metal selenides exhibit remarkable OER activity, their stability is compromised by the oxidative dissolution of selenium. The high-entropy materials can provide a feasible strategy to solve this problem due to their multi-element synergy and entropy stabilization effect. Here, we designed novel high-entropy MnCoCuZnAlSe2 electrocatalysts with ultra-low overpotential (190 mV@10 mA cm−2) and exceptional endurance (500 h@10 mA cm−2), which outperform other selenide and IrO2 catalysts. The high entropy effect was experimentally confirmed to inhibit selenium dissolution and improve the stability of transition metal selenides. Calculations using Density Functional Theory suggest that cobalt is actually MnCoCuZnAlSe2's true active center. The extraordinary OER properties of high-entropy selenides offer great opportunities for the design of ideal catalysts for practical applications.

Investigating the electrochemical performance of MnSe-supported SrZrO3 perovskite oxide nanocomposite as an electrode material for supercapacitor

Currently, the advancement in energy storage technology is a worldwide-based vital challenge, so researchers focused on the development and design of promising electrode materials for energy storage equipment. Perovskite oxide and transition metal selenide nanocomposites can achieve better cycle stability, efficient electric conductivity, high capacity, excellent redox reaction, and inattentive flexibility as electrode materials for energy storage devices and supercapacitor applications. Herein, we present the designed, fabricated, and electrochemical properties of MnSe-supported SrZrO3 nanocomposite via the Pechini method that exhibited more efficient capacitive performance than pristine SrZrO3 and MnSe. The result of electrochemical testing indicates that the SrZrO3–MnSe nanocomposite electrode possessed a battery-type pseudocapacitive nature and displayed a boosted specific capacitance of 1204 Fg-1 at a 5 mV/s scan rate in aqueous 1 M KOH solution under a three-electrode setup and maintained 95.2% retention after 3000th cycles. It also showed a higher electrochemical active surface area (1680.5 cm2), higher energy density (40 Wh/Kg), long-term cyclic stability performance, and enhanced rate capability compared to other prepared products. As a result, these findings have shown that SrZrO3–MnSe nanocomposite can be considered as potential electrode materials and might have emerging applications in commercial products for energy storage devices and supercapacitors.

Flower-like CoSe2/N, P-doped carbon microspheres accommodated on carbon nanosheets for high-performance potassium-ion batteries

Transition metal selenides (TMSs) have emerged as promising electrode materials for potassium-ion batteries (PIBs), whereas the large volume expansion and sluggish reaction kinetics have seriously hindered the cycle life and rate performance. Herein, a hierarchical composite of flower-like CoSe2/N, P-doped carbon microspheres accommodated on carbon nanosheets (CoSe2-NPC@CNS) was rationally fabricated as the anode for PIBs through a one-pot hydrothermal and subsequent selenization method. The intimate hybridization of CoSe2/N, P-doped carbon microspheres can effectively alleviate the volume expansion of CoSe2 during charge-discharge cycles, and the ultrathin carbon nanosheets derived from fluid catalytic cracking (FCC) slurry serves as a highly conductive and buffered substrate. By robustly merging them together, the interconnected hierarchical nanoarchitecture with exposed active sites achieves promoted potassium storage capacity, electrochemical reaction kinetics, and structural stability. As a result, the PIBs with CoSe2-NPC@CNS anode deliver high reversible capacities of 320.8 mAh g−1 after 100 cycles at 0.1 A g−1 and 213.9 mAh g−1 after 850 cycles at 1.0 A g−1, excellent rate capability (188.8 mAh g−1 at 5 A g−1), and enhanced pseudo-capacitive contribution rate of 88.7 %. This work offers valuable insight into the rational design and development of hierarchical anode materials with high performance for PIBs and beyond.

Facilitating Rapid Na+ Storage through MoWSe/C Heterostructure Construction and Synergistic Electrolyte Matching Strategy.

The realization of sodium-ion devices with high-power density and long-cycle capability is challenging due to the difficulties of carrier diffusion and electrode fragmentation in transition metal selenide anodes. Herein, a Mo/W-based metal-organic framework is constructed by a one-step method through rational selection, after which MoWSe/C heterostructures with large angles are synthesized by a facile selenization/carbonization strategy. Through physical characterization and theoretical calculations, the synthesized MoWSe/C electrode delivers obvious structural advantages and excellent electrochemical performance in an ethylene glycol dimethyl ether electrolyte. Furthermore, the electrochemical vehicle mechanism of ions in the electrolyte is systematically revealed through comparative analyses. Resultantly, ether-based electrolytes advantageously construct stable solid electrolyte interfaces and avoid electrolyte decomposition. Based on the above benefits, the Na half-cell assembled with MoWSe/C electrodes demonstrated excellent rate capability and a high specific capacity of 347.3 mA h g-1 even after cycling 2000 cycles at 10 A g-1. Meanwhile, the constructed sodium-ion capacitor maintains ∼80% capacity retention after 11,000 ultralong cycles at a high-power density of 3800 W kg-1. The findings can broaden the mechanistic understanding of conversion anodes in different electrolytes and provide a reference for the structural design of anodes with high capacity, fast kinetics, and long-cycle stability.

In situ confined growth of Cu2-xSe nanoparticles in highly defective nitrogen-doped carbon for high-rate sodium-ion battery anodes

Transition metal selenides are considered as hopeful anode materials for sodium-ion battery (SIB) due to the high specific capacity and rich reserves in nature. However, the inherent low conductivity of these anode materials, as well as the inevitable volume expansion and structural collapse during cycling, result in their poor rate performance and cycling stability. Herein, a universal selenization-co-carbonization strategy is proposed to synthesize Cu2-xSe nanoparticles in-situ confined in highly defective nitrogen-doped carbon (Cu2-xSe@NC) with superior architectural features, which involves simultaneous selenization and carbonization procedure of octahedral metal–organic framework (Cu-BTC) precursor. The nitrogen-doped carbon matrix stabilizes/confines the Cu2-xSe nanoparticles to prevent their agglomeration and volume expansion during cycling while endowing high electrical conductivity to the hybrid materials. As anode for SIBs, the Cu2-xSe@NC exhibits a high reversible capacity of 340 mAh/g at 0.1 A/g with a high initial coulombic efficiency of 70 %, superior rate performance (capacity retention of 82.4 % from 0.02 to 5 A/g), and long-cycle durability. The ex-situ XRD and HRTEM techniques confirmed that Cu2-xSe undergoes complex intercalation and crystal evolution accompanied by reversible intermediate phases (NaCuSe and Na2Se) transformation during charge/discharge cycle. First-principles calculations and in-situ EIS confirmed that the intercalation of Na+ can greatly reducing the energy band gap and improving the electrical conductivity of Cu2-xSe@NC, thereby achieving excellent rate performance. Moreover, the Cu2-xSe@NC anode is also evaluated by matching with Na3V2(PO4)3 cathode to assemble a full SIB, which can provide high initial capacity and capacity retention, revealing its potential for practical application.

Enhancing sodium storage through tri-phase heterointerfaces in Co–Fe–MoSe2@N-doped carbon nanocubes with self-generated rich phase boundaries

Transition metal selenides have received considerable research interest as conversion-type anodes owing to their impressive theoretical specific capacity and high conversion reaction efficiency. Nevertheless, the practical application of these materials is constrained by the low intrinsic conductivity and substantial volume changes during repetitive cycles, which leads to electrode structure deterioration, reduced cyclic stability, and poor rate performance. Herein, a trimetallic selenide Co–Fe–MoSe2@N-doped carbon composite with self-generated abundant phase boundaries was successfully designed using a straightforward co-precipitation method followed by a selenization process. The hybrid material, with its inherent self-generated electric field at the heterojunction surfaces, significantly improves the reaction kinetics. Moreover, the experimental results, complemented with density functional theory calculations, also illustrate that the enriched heterostructure boundaries provide ample electrochemical reaction active sites, thereby boosting charge transfer efficiency and mitigating the Na+ diffusion barrier. Remarkably, the composite exhibits excellent cyclic performance, achieving 322.4 mAh g−1 at 5 A g−1 after 1000 cycles, surpassing the performance of various other metal selenides. This innovative approach of creating abundant phase boundaries through the heterostructured ternary metal selenide presents a promising avenue for advancing the practical application of conversion-type anode materials.

Heterogeneous engineering and carbon confinement strategy to synergistically boost the sodium storage performance of transition metal selenides

Transition metal selenides (TMSs) stand out as a promising anode material for sodium-ion batteries (SIBs) owing to their natural resources and exceptional sodium storage capacity. Despite these advantages, their practical application faces challenges, such as poor electronic conductivity, sluggish reaction kinetics and severe agglomeration during electrochemical reactions, hindering their effective utilization. Herein, the dual-carbon-confined CoSe2/FeSe2@NC@C nanocubes with heterogeneous structure are synthesized using ZIF-67 as the template by ion exchange, resorcin-formaldehyde (RF) coating, and subsequent in situ carbonization and selenidation. The N-doped porous carbon promotes rapid electrolyte penetration and minimizes the agglomeration of active materials during charging and discharging, while the RF-derived carbon framework reduces the cycling stress and keeps the integrity of the material structure. More importantly, the built-in electric field at the heterogeneous boundary layer drives electron redistribution, optimizing the electronic structure and enhancing the reaction kinetics of the anode material. Based on this, the nanocubes of CoSe2/FeSe2@NC@C exhibits superb sodium storage performance, delivering a high discharge capacity of 512.6 mA h g−1 at 0.5 A g−1 after 150 cycles and giving a discharge capacity of 298.2 mA h g−1 at 10 A g−1 with a CE close to 100.0 % even after 1000 cycles. This study proposes a viable method to synthesize advanced anodes for SIBs by a synergy effect of heterogeneous interfacial engineering and a carbon confinement strategy.