Designed Formation of Hybrid Nanobox Composed of Carbon Sheathed CoSe2 Anchored on Nitrogen‐Doped Carbon Skeleton as Ultrastable Anode for Sodium‐Ion Batteries

Research on sodium‐ion batteries (SIBs) has recently been revitalized due to the unique features of much lower costs and comparable energy/power density to lithium‐ion batteries (LIBs), which holds great potential for grid‐level energy storage systems. Transition metal dichalcogenides (TMDCs) are considered as promising anode candidates for SIBs with high theoretical capacity, while their intrinsic low electrical conductivity and large volume expansion upon Na⁺ intercalation raise the challenging issues of poor cycle stability and inferior rate performance. Herein, the designed formation of hybrid nanoboxes composed of carbon‐protected CoSe₂ nanoparticles anchored on nitrogen‐doped carbon hollow skeletons (denoted as CoSe₂@C∩NC) via a template‐assisted refluxing process followed by conventional selenization treatment is reported, which exhibits tremendously enhanced electrochemical performance when applied as the anode for SIBs. Specifically, it can deliver a high reversible specific capacity of 324 mAh g^?1 at current density of 0.1 A g^?1 after 200 cycles and exhibit outstanding high rate cycling stability at the rate of 5 A g^?1 over 2000 cycles. This work provides a rational strategy for the design of advanced hybrid nanostructures as anode candidates for SIBs, which could push forward the development of high energy and low cost energy storage devices.     

Unique Cobalt Sulfide/Reduced Graphene Oxide Composite as an Anode for Sodium‐Ion Batteries with Superior Rate Capability and Long Cycling Stability

Exploitation of high‐performance anode materials is essential but challenging to the development of sodium‐ion batteries (SIBs). Among all proposed anode materials for SIBs, sulfides have been proved promising candidates due to their unique chemical and physical properties. In this work, a facile solvothermal method to in situ decorate cobalt sulfide (CoS) nanoplates on reduced graphene oxide (rGO) to build CoS@rGO composite is described. When evaluated as anode for SIBs, an impressive high specific capacity (540 mAh g^?1 at 1 A g^?1), excellent rate capability (636 mAh g^?1 at 0.1 A g^?1 and 306 mAh g^?1 at 10 A g^?1), and extraordinarily cycle stability (420 mAh g^?1 at 1 A g^?1 after 1000 cycles) have been demonstrated by CoS@rGO composite for sodium storage. The synergetic effect between the CoS nanoplates and rGO matrix contributes to the enhanced electrochemical performance of the hybrid composite. The results provide a facile approach to fabricate promising anode materials for high‐performance SIBs.     

Self‐Supporting,Flexible, Additive‐Free,and Scalable Hard Carbon Paper Self‐Interwoven by 1D Microbelts: Superb Room/Low‐Temperature Sodium Storage and Working Mechanism

Hard carbon is regarded as a promising anode material for sodium‐ion batteries (SIBs). However, it usually suffers from the issues of low initial Coulombic efficiency (ICE) and poor rate performance, severely hindering its practical application. Herein, a flexible, self‐supporting, and scalable hard carbon paper (HCP) derived from scalable and renewable tissue is rationally designed and prepared as practical additive‐free anode for room/low‐temperature SIBs with high ICE. In ether electrolyte, such HCP achieves an ICE of up to 91.2% with superior high‐rate capability, ultralong cycle life (e.g., 93% capacity retention over 1000 cycles at 200 mA g^?1) and outstanding low‐temperature performance. Working mechanism analyses reveal that the plateau region is the rate‐determining step for HCP with a lower electrochemical reaction kinetics, which can be significantly improved in ether electrolyte.     

Bismuth Nanoparticle@Carbon Composite Anodes for Ultralong Cycle Life and High‐Rate Sodium‐Ion Batteries

Bismuth has emerged as a promising anode material for sodium‐ion batteries (SIBs), owing to its high capacity and suitable operating potential. However, large volume changes during alloying/dealloying processes lead to poor cycling performance. Herein, bismuth nanoparticle@carbon (Bi@C) composite is prepared via a facile annealing method using a commercial coordination compound precursor of bismuth citrate. The composite has a uniform structure with Bi nanoparticles embedded within a carbon framework. The nanosized structure ensures a fast kinetics and efficient alleviation of stress/strain caused by the volume change, and the resilient and conductive carbon matrix provides an interconnected electron transportation pathway. The Bi@C composite delivers outstanding sodium‐storage performance with an ultralong cycle life of 30 000 cycles at a high current density of 8 A g^?1 and an excellent rate capability of 71% capacity retention at an ultrahigh current rate of 60 A g^?1. Even at a high mass loading of 11.5 mg cm^?2, a stable reversible capacity of 280 mA h g^?1 can be obtained after 200 cycles. More importantly, full SIBs by pairing with a Na₃V₂(PO₄)₃ cathode demonstrates superior performance. Combining the facile synthesis and the commercial precursor, the exceptional performance makes the Bi@C composite very promising for practical large‐scale applications.     

Focus on Spinel Li4Ti5O12 as Insertion Type Anode for High‐Performance Na‐Ion Batteries

Sodium‐ion batteries (SIBs) toward large‐scale energy storage applications has fascinated researchers in recent years owing to the low cost, environmental friendliness, and inestimable abundance. The similar chemical and electrochemical properties of sodium and lithium make sodium an easy substitute for lithium in lithium‐ion batteries. However, the main issues of limited cycle life, low energy density, and poor power density hamper the commercialization process. In the last few years, the development of electrode materials for SIBs has been dedicated to improving sodium storage capacities, high energy density, and long cycle life. The insertion type spinel Li₄Ti₅O₁₂ (LTO) possesses “zero‐strain” behavior that offers the best cycle life performance among all reported oxide‐based anodes, displaying a capacity of 155 mAh g^?1 via a three‐phase separation mechanism, and competing for future topmost high energy anode for SIBs. Recent reports offer improvement of overall electrode performance through carbon coating, doping, composites with metal oxides, and surface modification techniques, etc. Further, LTO anode with its structure and properties for SIBs is described and effective methods to improve the LTO performance are discussed in both half‐cell and practical configuration, i.e., full‐cell, along with future perspectives and solutions to promote its use.     

Confined Amorphous Red Phosphorus in MOF‐Derived N‐Doped Microporous Carbon as a Superior Anode for Sodium‐Ion Battery

Red phosphorus (P) has attracted intense attention as promising anode material for high‐energy density sodium‐ion batteries (NIBs), owing to its high sodium storage theoretical capacity (2595 mAh g^?1). Nevertheless, natural insulating property and large volume variation of red P during cycling result in extremely low electrochemical activity, leading to poor electrochemical performance. Herein, the authors demonstrate a rational strategy to improve sodium storage performance of red P by confining nanosized amorphous red P into zeolitic imidazolate framework‐8 (ZIF‐8) ‐derived nitrogen‐doped microporous carbon matrix (denoted as P@N‐MPC). When used as anode for NIBs, the P@N‐MPC composite displays a high reversible specific capacity of ≈600 mAh g^?1 at 0.15 A g^?1 and improved rate capacity (≈450 mAh g^?1 at 1 A g^?1 after 1000 cycles with an extremely low capacity fading rate of 0.02% per cycle). The superior sodium storage performance of the P@N‐MPC is mainly attributed to the novel structure. The N‐doped porous carbon with sub‐1 nm micropore facilitates the rapid diffusion of organic electrolyte ions and improves the conductivity of the encapsulated red P. Furthermore, the porous carbon matrix can buffer the volume change of red P during repeat sodiation/desodiation process, keeping the structure intact after long cycle life.     

High‐Performance Sodium‐Ion Battery Anode via Rapid Microwave Carbonization of Natural Cellulose Nanofibers with Graphene Initiator

Cellulose is a promising natural bio‐macromolecule due to its abundance, renewability and low cost. Here, a new method is developed to prepare pre‐sodiated carbonaceous anodes for sodium‐ion batteries (SIBs) from cellulose nanofibers (CNFs) under microwave irradiation for potential ultrafast and large‐scale manufacturing. While direct carbonization of CNFs through microwave treatment is usually impossible due to the weak microwave absorption of CNFs, it is found that a small amount of reduced graphene oxide (rGO) can act as an effective initiator. Microwaving rGO releases extremely high energy, giving rise to local ultrahigh temperature as well as ultrahigh heating rate, which then induces the fast carbonization of CNFs and the production of pre‐sodiated carbonaceous materials within seconds. The sodium in the carbonaceous materials, introduced from the carbonization of CNFs containing sodium‐ion carboxyl, offer favorable spaces for sodiation/desodiation, which improves the electrochemical performance of the sodium‐inserted carbonaceous anode. When the microwaved rGO‐CNF (MrGO‐CNF) is used as an anode for SIBs, a high initial capacity of 558 mAh g^?1 is delivered and the capacity of 340 mAh g^?1 remains after 200 cycles. The excellent reversible capacity and cycling stability indicate MrGO‐CNF a promising anode for sodium‐ion batteries.     

Recent Progress in Rechargeable Sodium‐Ion Batteries: toward High‐Power Applications

The increasing demands for renewable energy to substitute traditional fossil fuels and related large‐scale energy storage systems (EES) drive developments in battery technology and applications today. The lithium‐ion battery (LIB), the trendsetter of rechargeable batteries, has dominated the market for portable electronics and electric vehicles and is seeking a participant opportunity in the grid‐scale battery market. However, there has been a growing concern regarding the cost and resource availability of lithium. The sodium‐ion battery (SIB) is regarded as an ideal battery choice for grid‐scale EES owing to its similar electrochemistry to the LIB and the crust abundance of Na resources. Because of the participation in frequency regulation, high pulse‐power capability is essential for the implanted SIBs in EES. Herein, a comprehensive overview of the recent advances in the exploration of high‐power cathode and anode materials for SIB is presented, and deep understanding of the inherent host structure, sodium storage mechanism, Na⁺ diffusion kinetics, together with promising strategies to promote the rate performance is provided. This work may shed light on the classification and screening of alternative high rate electrode materials and provide guidance for the design and application of high power SIBs in the future.     

The State and Challenges of Anode Materials Based on Conversion Reactions for Sodium Storage

Sodium‐ion batteries (SIBs) have huge potential for applications in large‐scale energy storage systems due to their low cost and abundant sources. It is essential to develop new electrode materials for SIBs with high performance in terms of energy density, cycle life, and cost. Metal binary compounds that operate through conversion reactions hold promise as advanced anode materials for sodium storage. This Review highlights the storage mechanisms and advantages of conversion‐type anode materials and summarizes their recent development. Although conversion‐type anode materials have high theoretical capacities and abundant varieties, they suffer from multiple challenging obstacles to realize commercial applications, such as low reversible capacity, large voltage hysteresis, low initial coulombic efficiency, large volume changes, and low cycling stability. These key challenges are analyzed in this Review, together with emerging strategies to overcome them, including nanostructure and surface engineering, electrolyte optimization, and battery configuration designs. This Review provides pertinent insights into the prospects and challenges for conversion‐type anode materials, and will inspire their further study.     

Hierarchical Porous Nanosheets Constructed by Graphene‐Coated,Interconnected TiO2 Nanoparticles for Ultrafast Sodium Storage

Sodium‐ion batteries (SIBs) are considered promising next‐generation energy storage devices. However, a lack of appropriate high‐performance anode materials has prevented further improvements. Here, a hierarchical porous hybrid nanosheet composed of interconnected uniform TiO₂ nanoparticles and nitrogen‐doped graphene layer networks (TiO₂@NFG HPHNSs) that are synthesized using dual‐functional C₃N₄ nanosheets as both the self‐sacrificing template and hybrid carbon source is reported. These HPHNSs deliver high reversible capacities of 146 mA h g^?1 at 5 C for 8000 cycles, 129 mA h g^?1 at 10 C for 20 000 cycles, and 116 mA h g^?1 at 20 C for 10 000 cycles, as well as an ultrahigh rate capability up to 60 C with a capacity of 101 mA h g^?1. These results demonstrate the longest cyclabilities and best rate capability ever reported for TiO₂‐based anode materials for SIBs. The unprecedented sodium storage performance of the TiO₂@NFG HPHNSs is due to their unique composition and hierarchical porous 2D structure.     

Porous Carbon Nanofibers Encapsulated with Peapod‐Like Hematite Nanoparticles for High‐Rate and Long‐Life Battery Anodes

Fe₂O₃ is regarded as a promising anode material for lithium‐ion batteries (LIBs) and sodium‐ion batteries (SIBs) due to its high specific capacity. The large volume change during discharge and charge processes, however, induces significant cracking of the Fe₂O₃ anodes, leading to rapid fading of the capacity. Herein, a novel peapod‐like nanostructured material, consisting of Fe₂O₃ nanoparticles homogeneously encapsulated in the hollow interior of N‐doped porous carbon nanofibers, as a high‐performance anode material is reported. The distinctive structure not only provides enough voids to accommodate the volume expansion of the pea‐like Fe₂O₃ nanoparticles but also offers a continuous conducting framework for electron transport and accessible nanoporous channels for fast diffusion and transport of Li/Na‐ions. As a consequence, this peapod‐like structure exhibits a stable discharge capacity of 1434 mAh g^?1 (at 100 mA g^?1) and 806 mAh g^?1 (at 200 mA g^?1) over 100 cycles as anode materials for LIBs and SIBs, respectively. More importantly, a stable capacity of 958 mAh g^?1 after 1000 cycles and 396 mAh g^?1 after 1500 cycles can be achieved for LIBs and SIBs, respectively, at a large current density of 2000 mA g^?1. This study provides a promising strategy for developing long‐cycle‐life LIBs and SIBs.     

Ultrahigh Rate Performance of Hollow Antimony Nanoparticles Impregnated in Open Carbon Boxes for Sodium‐Ion Battery under Elevated Temperature

Antimony is a competitive and promising anode material for sodium‐ion batteries (SIBs) due to its high theoretical capacity. However, the poor rate capability and fast capacity fading greatly restrict its practical application. To address the above issues, a facile and eco‐friendly sacrificial template method is developed to synthesize hollow Sb nanoparticles impregnated in open carbon boxes (Sb HPs@OCB). The as‐obtained Sb HPs@OCB composite exhibits excellent sodium storage properties even when operated at an elevated temperature of 50 °C, delivering a robust rate capability of 345 mAh g^?1 at 16 A g^?1 and rendering an outstanding reversible capacity of 187 mAh g^?1 at a high rate of 10 A g^?1 after 300 cycles. Such superior electrochemical performance of the Sb HPs@OCB can be attributed to the comprehensive characteristics of improved kinetics derived from hollow Sb nanoparticles impregnated into 2D carbon nanowalls, the existence of robust Sb? O? C bond, and enhanced pseudocapacitive behavior. All those factors enable Sb HPs@OCB great potential and distinct merit for large‐scale energy storage of SIBs.     

Metal Cation‐Assisted Synthesis of Amorphous B,N Co‐Doped Carbon Nanotubes for Superior Sodium Storage

Nearly inexhaustible sodium sources on earth make sodium ion batteries (SIBs) the best candidate for large‐scale energy storage. However, the main obstacles faced by SIBs are the low rate performance and poor cycle stability caused by the large size of Na⁺ ions. Herein, a universal strategy for synthesizing amorphous metals encapsulated into amorphous B, N co‐doped carbon (a‐M@a‐BCN; M = Co, Ni, Mn) nanotubes by metal cation‐assisted carbonization is explored. The methodology allows tailoring the structures (e.g., length, wall thickness, and metals doping) of a‐M@a‐BCN nannotubes at the molecular level. Furthermore, the amorphous metal sulfide encapsulated into a‐BCN (a‐MS_x@a‐BCN; MS_x: CoS, Ni₃S₂, MnS) nanotubes are obtained by one‐step sulfidation process. The a‐M@a‐BCN and a‐MS_x@a‐BCN possess the larger interlayer spacing (0.40 nm) amorphous carbon nanotube rich in heteroatoms active sites, making them exhibit excellent Na⁺ ions diffusion kinetics and capacitive storage behavior. As SIBs anodes, they show high capacity, excellent rate performance, and long cycle stability.     

Recent Progress in Iron‐Based Electrode Materials for Grid‐Scale Sodium‐Ion Batteries

Grid‐scale energy storage batteries with electrode materials made from low‐cost, earth‐abundant elements are needed to meet the requirements of sustainable energy systems. Sodium‐ion batteries (SIBs) with iron‐based electrodes offer an attractive combination of low cost, plentiful structural diversity and high stability, making them ideal candidates for grid‐scale energy storage systems. Although various iron‐based cathode and anode materials have been synthesized and evaluated for sodium storage, further improvements are still required in terms of energy/power density and long cyclic stability for commercialization. In this Review, progress in iron‐based electrode materials for SIBs, including oxides, polyanions, ferrocyanides, and sulfides, is briefly summarized. In addition, the reaction mechanisms, electrochemical performance enhancements, structure–composition–performance relationships, merits and drawbacks of iron‐based electrode materials for SIBs are discussed. Such iron‐based electrode materials will be competitive and attractive electrodes for next‐generation energy storage devices.     

Ion Reservoir Enabled by Hierarchical Bimetallic Sulfides Nanocages Toward Highly Effective Sodium Storage

Designing and constructing bimetallic hierarchical structures is vital for the conversion‐alloy reaction anode of sodium‐ion batteries (SIBs). Particularly, the rationally designed hetero‐interface engineering can offer fast diffusion kinetics in the interface, leading to the improved high‐power surface pseudocapacitance and cycling stability for SIBs. Herein, the hierarchical zinc–tin sulfide nanocages (ZnS‐NC/SnS₂) are constructed through hydrothermal and sulfuration reactions. The unconventional hierarchical design with internal void space greatly optimizes the structure stability, and bimetallic sulfide brings a bimetallic composite interface and N heteroatom doping, which are devoted to high electrochemical activity and improved interfacial charge transfer rate for Na⁺ storage. Remarkably, the ZnS‐NC/SnS₂ composite anode exhibits a delightful reversible capacity of 595 mAh g^?1 after 100 cycles at 0.2 A g^?1, and long cycling capability for 500 cycles with a low capacity loss of 0.08% per cycle at 1 A g^?1. This study opens up a new route for rationally constructing hierarchical heterogeneous interfaces and sheds new light on efficient anode material for SIBs.     

Bulk Bismuth as a High‐Capacity and Ultralong Cycle‐Life Anode for Sodium‐Ion Batteries by Coupling with Glyme‐Based Electrolytes

Sodium‐ion batteries (SIBs) have attracted great interest for large‐scale electric energy storage in recent years. However, anodes with long cycle life and large reversible capacities are still lacking and therefore limiting the development of SIBs. Here, a bulk Bi anode with surprisingly high Na storage performance in combination with glyme‐based electrolytes is reported. This study shows that the bulk Bi electrode is gradually developed into a porous integrity during initial cycling, which is totally different from that in carbonate‐based electrolytes and ensures facile Na⁺ transport and structural stability. The achievable capacity of bulk Bi in the NaPF₆‐diglyme electrolyte is high up to 400 mAh g^?1, and the capacity retention is 94.4% after 2000 cycles, corresponding to a capacity loss of 0.0028% per cycle. It exhibits two flat discharge/charge plateaus at 0.67/0.77 and 0.46/0.64 V, ascribed to the typical two‐phase reactions of Bi ? NaBi and NaBi ? Na₃Bi, respectively. The excellent performance is attributed to the unique porous integrity, stable solid electrolyte interface, and good electrode wettability of glymes. This interplay between electrolyte and electrode to boost Na storage performance will pave a new pathway for high‐performance SIBs.     

High‐Energy/Power and Low‐Temperature Cathode for Sodium‐Ion Batteries: In Situ XRD Study and Superior Full‐Cell Performance

Sodium‐ion batteries (SIBs) are still confronted with several major challenges, including low energy and power densities, short‐term cycle life, and poor low‐temperature performance, which severely hinder their practical applications. Here, a high‐voltage cathode composed of Na₃V₂(PO₄)₂O₂F nano‐tetraprisms (NVPF‐NTP) is proposed to enhance the energy density of SIBs. The prepared NVPF‐NTP exhibits two high working plateaux at about 4.01 and 3.60 V versus the Na⁺/Na with a specific capacity of 127.8 mA h g^?1. The energy density of NVPF‐NTP reaches up to 486 W h kg^?1, which is higher than the majority of other cathode materials previously reported for SIBs. Moreover, due to the low strain (≈2.56% volumetric variation) and superior Na transport kinetics in Na intercalation/extraction processes, as demonstrated by in situ X‐ray diffraction, galvanostatic intermittent titration technique, and cyclic voltammetry at varied scan rates, the NVPF‐NTP shows long‐term cycle life, superior low‐temperature performance, and outstanding high‐rate capabilities. The comparison of Ragone plots further discloses that NVPF‐NTP presents the best power performance among the state‐of‐the‐art cathode materials for SIBs. More importantly, when coupled with an Sb‐based anode, the fabricated sodium‐ion full‐cells also exhibit excellent rate and cycling performances, thus providing a preview of their practical application.     

In Situ Carbon‐Doped Mo(Se0.85S0.15)2 Hierarchical Nanotubes as Stable Anodes for High‐Performance Sodium‐Ion Batteries

Sodium‐ion batteries (SIBs) are promising energy storage devices, but suffer from poor cycling stability and low rate capability. In this work, carbon doped Mo(Se_0.85S_0.15)₂ (i.e., Mo(Se_0.85S_0.15)₂:C) hierarchical nanotubes have been synthesized for the first time and serve as a robust and high‐performance anode material. The hierarchical nanotubes with diameters of 300 nm and wall thicknesses of 50 nm consist of numerous 2D layered nanosheets, and can act as a robust host for sodiation/desodiation cycling. The Mo(Se_0.85S_0.15)₂:C hierarchical nanotubes deliver a discharge capacity of 360 mAh g⁻¹ at a high current density of 2000 mA g⁻¹ and keep a 81.8% capacity retention compared to that at a current density of 50 mA g⁻¹, showing superior rate capability. Comparing with the second cycle discharge capacities, the nanotube anode can maintain capacities of 102.2%, 101.9%, and 97.8% after 100 cycles at current densities of 200, 500, and 1000 mA g⁻¹, respectively. This work demonstrates the best cycling performance and high‐rate sodium storage capabilities of MoSe₂ for SIBs to date. The hollow interior, hierarchical organization, layered structure, and carbon doping are beneficial for fast Na⁺‐ion and electron kinetics and are responsible for the stable cycling performance and high rate capabilities.     

A 1D Honeycomb‐Like Amorphous Zincic Vanadate for Stable and Fast Sodium‐Ion Storage

Developing nanomaterials with synergistic effects of various structural merits is considered to be an effective strategy to improve the sluggish ion kinetics and severe structural degradation of sodium‐ion battery (SIB) anodes. Herein, honeycomb‐like amorphous Zn₂V₂O₇ (ZVO‐AH) nanofibers as SIBs anode material with plentiful defective sites, complex cavities, and good mechanical flexibility are reported. The fabrication strategy relies on the expansive and volatile nature of the organic vanadium source, based on a simple electrospinning with subsequent calcination. Originating from the synergies of amorphous nature and honeycomb‐like cavities, ZVO‐AH shows increased electrochemical activity, accelerated Na‐ion diffusion, and robust structure. Impressively, the ZVO‐AH anode delivers superior cycle stability (112% retention at 5 A g^?1 after 5000 cycles) and high rate capability (150 mAh g^?1 at 10 A g^?1). The synthetic versatility is able to synergistically promote the practical application of more potential materials in sodium‐ion storage.     

Urchin‐Like Fe3Se4 Hierarchitectures: A Novel Pseudocapacitive Sodium‐Ion Storage Anode with Prominent Rate and Cycling Properties

Transition metal chalcogenides have received great attention as promising anode candidates for sodium‐ion batteries (SIBs). However, the undesirable cyclic life and inferior rate capability still restrict their practical applications. The design of micro–nano hierarchitectures is considered as a possible strategy to facilitate the electrochemical reaction kinetics and strengthen the electrode structure stability upon repeated Na⁺ insertion/extraction. Herein, urchin‐like Fe₃Se₄ hierarchitectures are successfully prepared and developed as a novel anode material for SIBs. Impressively, the as‐prepared urchin‐like Fe₃Se₄ can present an ultrahigh rate capacity of 200.2 mAh g^‐1 at 30 A g^‐1 and a prominent capacity retention of 99.9% over 1000 cycles at 1 A g^‐1, meanwhile, a respectable initial coulombic efficiency of ≈100% is achieved. Through the conjunct study of in situ X‐ray diffraction, ex situ X‐ray absorption near‐edge structure spectroscopy, as well as cyclic voltammetry curves, it is intriguing to reveal that the phase transformation from monoclinic to amorphous structure accompanied by the pseudocapacitive Na⁺ storage behavior accounts for the superior electrochemical performance. When paired with the Na₃V₂(PO₄)₃ cathode materials, the assembled full cell enables high energy density and decent cyclic stability, demonstrating potential practical feasibility of the present urchin‐like Fe₃Se₄ anode.