Formation of Uniform N‐doped Carbon‐Coated SnO2 Submicroboxes with Enhanced Lithium Storage Properties

Rational design and preparation of SnO₂‐based materials with superior electrochemical performance for lithium‐ion batteries are highly desirable. In this work, the synthesis of SnO₂/nitrogen‐doped carbon (SnO₂/NC) submicroboxes with excellent lithium storage properties is reported. The as‐synthesized SnO₂/NC submicroboxes are highly porous with a high specific surface area of 125 m² g^?1, well‐defined hollow structure (around 400 nm in size) with a shell thickness of 40 nm, and ultrasmall SnO₂ nanoparticles uniformly coated with nitrogen‐doped carbon layer. As a result, the SnO₂/NC submicroboxes show outstanding electrochemical performance as an anode material for lithium‐ion batteries. A high reversible capacity of 491 mAh g^?1 can be retained after 100 cycles at a current density of 0.5 A g^?1.     

In Situ Generation of Few‐Layer Graphene Coatings on SnO2‐SiC Core‐Shell Nanoparticles for High‐Performance Lithium‐Ion Storage

A simple ball‐milling method is used to synthesize a tin oxide‐silicon carbide/few‐layer graphene core‐shell structure in which nanometer‐sized SnO₂ particles are uniformly dispersed on a supporting SiC core and encapsulated with few‐layer graphene coatings by in situ mechanical peeling. The SnO₂‐SiC/G nanocomposite material delivers a high reversible capacity of 810 mA h g^?1 and 83% capacity retention over 150 charge/discharge cycles between 1.5 and 0.01 V at a rate of 0.1 A g^?1. A high reversible capacity of 425 mA h g^?1 also can be obtained at a rate of 2 A g^?1. When discharged (Li extraction) to a higher potential at 3.0 V (vs. Li/Li⁺), the SnO₂‐SiC/G nanocomposite material delivers a reversible capacity of 1451 mA h g^?1 (based on the SnO₂ mass), which corresponds to 97% of the expected theoretical capacity (1494 mA h g^?1, 8.4 equivalent of lithium per SnO₂), and exhibits good cyclability. This result suggests that the core‐shell nanostructure can achieve a completely reversible transformation from Li_4.4Sn to SnO₂ during discharging (i.e., Li extraction by dealloying and a reversible conversion reaction, generating 8.4 electrons). This suggests that simple mechanical milling can be a powerful approach to improve the stability of high‐performance electrode materials involving structural conversion and transformation.     

Sn‐Alloy Foil Electrode with Mechanical Prelithiation: Full‐Cell Performance up to 200 Cycles

Self‐supporting Sn foil is a promising high‐volumetric‐capacity anode for lithium ion batteries (LIBs), but it suffers from low initial Coulombic efficiency (ICE). Here, mechanical prelithiation is adopted to improve ICE, and it is found that Sn foils with coarser grains are prone to cause electrode damage. To mitigate damage and prepare thinner lithiated electrodes, 3Ag0.5Cu96.5Sn foil is used that has more refined grains (5–10 µm) instead of Sn (50–100 µm), where the abundant grain boundaries (GBs) offer more sliding systems to release stress and reduce deep fractures. Thus, the thickness of Li_x3Ag0.5Cu96.5Sn can be reduced to 50 µm, compared to 100 µm Li_xSn. When the foils contact open air, the Sn‐Li‐O(H) products are more stable than Li‐O(H), thus Li_x3Ag0.5Cu96.5Sn shows outstanding air stability. The as‐prepared 50 µm foil anode achieves stable 200 cycles in LiFePO₄//Li_x3Ag0.5Cu96.5Sn full cell (≈2.65 mAh cm^?2) and the capacity retention is 95%. Even at 5C, the capacity of Li_x3Ag0.5Cu96.5Sn is still up to ≈1.8 mAh cm^?2. The cycle life of NCM523//Li_x3Ag0.5Cu96.5Sn full cell exceeds that of NCM523//Li. Furthermore, 70 µm Li_x3Ag0.5Cu96.5Sn is used as double‐sided anode for a 3 cm × 2.8 cm pouch cell and its actual volumetric capacity density is 674 mAh cm^?3 after 50 cycles.     

Controlled SnO2 Crystallinity Effectively Dominating Sodium Storage Performance

The exploration of sodium ion batteries (SIBs) is a profound challenge due to the rich sodium abundance and limited supply of lithium on earth. Here, amorphous SnO₂/graphene aerogel (a‐SnO₂/GA) nanocomposites have been successfully synthesized via a hydrothermal method for use as anode materials in SIBs. The designed annealing process produces crystalline SnO₂/graphene aerogel (c‐SnO₂/GA) nanocomposites. For the first time, the significant effects of SnO₂ crystallinity on sodium storage performance are studied in detail. Notably, a‐SnO₂/GA is more effective than c‐SnO₂/GA in overcoming electrode degradation from large volume changes associated with charge–discharge processes. Surprisingly, the amorphous SnO₂ delivers a high specific capacity of 380.2 mAh g^?1 after 100 cycles at a current density of 50 mA g^?1, which is almost three times as much as for crystalline SnO₂ (138.6 mAh g^?1). The impressive electrochemical performance of amorphous SnO₂ can be attributed to the intrinsic isotropic nature, the enhanced Na⁺ diffusion coefficient, and the strong interaction between amorphous SnO₂ and GA. In addition, amorphous SnO₂ particles with the smaller size better function to relieve the volume expansion/shrinkage. This study provides a significant research direction aiming to increase the electrochemical performance of the anode materials used in SIBs.     

Understanding Ostwald Ripening and Surface Charging Effects in Solvothermally‐Prepared Metal Oxide–Carbon Anodes for High Performance Rechargeable Batteries

Metal oxides synthesized by the solvothermal approach have widespread applications, while their nanostructure control remains challenging because their reaction mechanism is still not fully understood. Herein, it is demonstrated how the competitive relation between Ostwald ripening and surface charging during solvothermal synthesis is crucial to engineering high‐quality metal (oxide)–carbon nanomaterials. Using SnO₂ as a case study, a new type of hollow SnO₂–C hybrid nanoparticles is synthesized consisting of core–shell structured SnO₂@C nanodots (which has not been previously reported). This new anode material exhibits extremely high lithium storage capacity of 1225 and 955 mAh g^?1 at 200 and 500 mA g^?1, respectively, and excellent cycling stability. In addition, full‐battery cells are constructed combining SnO₂–C anode with Ni‐rich cathode, which can be charged to a higher voltage compared to commercial graphite anode and still demonstrate extraordinary rate performance. This study provides significant insight into the largely unexplored reaction mechanism during solvothermal synthesis, and demonstrates how such understanding can be used to achieve high‐performance metal (oxide)–C anodes for rechargeable batteries.     

A Conductive Molecular Framework Derived Li2S/N,P‐Codoped Carbon Cathode for Advanced Lithium–Sulfur Batteries

Li₂S is one of the most promising cathode materials for Li‐ion batteries because of its high theoretical capacity and compatibility with Li‐metal‐free anode materials. However, the poor conductivity and electrochemical reactivity lead to low initial capacity and severe capacity decay. In this communication, a nitrogen and phosphorus codoped carbon (N,P–C) framework derived from phytic acid doped polyaniline hydrogel is designed to support Li₂S nanoparticles as a binder‐free cathode for Li–S battery. The porous 3D architecture of N and P codoped carbon provides continuous electron pathways and hierarchically porous channels for Li ion transport. Phosphorus doping can also suppress the shuttle effect through strong interaction between sulfur and the carbon framework, resulting in high Coulombic efficiency. Meanwhile, P doping in the carbon framework plays an important role in improving the reaction kinetics, as it may help catalyze the redox reactions of sulfur species to reduce electrochemical polarization, and enhance the ionic conductivity of Li₂S. As a result, the Li₂S/N,P–C composite electrode delivers a stable capacity of 700 mA h g^?1 with average Coulombic efficiency of 99.4% over 100 cycles at 0.1C and an areal capacity as high as 2 mA h cm^?2 at 0.5C.     

Sodium Plating from Na‐β″‐Alumina Ceramics at Room Temperature,Paving the Way for Fast‐Charging All‐Solid‐State Batteries

All‐solid‐state batteries with an alkali metal anode have the potential to achieve high energy density. However, the onset of dendrite formation limits the maximum plating current density across the solid electrolyte and prevents fast charging. It is shown that the maximum plating current density is related to the interfacial resistance between the solid electrolyte and the metal anode. Due to their high ionic conductivity, low electronic conductivity, and stability against sodium metal, Na‐β″‐alumina ceramics are excellent candidates as electrolytes for room‐temperature all‐solid‐state batteries. Here, it is demonstrated that a heat treatment of Na‐β″‐alumina ceramics in argon atmosphere enables an interfacial resistance <10 Ω cm² and current densities up to 12 mA cm^?2 at room temperature. The current density obtained for Na‐β″‐alumina is ten times higher than that measured on a garnet‐type Li₇La₃Zr₂O₁₂ electrolyte under equivalent conditions. X‐ray photoelectron spectroscopy shows that eliminating hydroxyl groups and carbon contaminations at the interface between Na‐β″‐alumina and sodium metal is key to reach such values. By comparing the temperature‐dependent stripping/plating behavior of Na‐β″‐alumina and Li₇La₃Zr₂O₁₂, the role of the alkali metal in governing interface kinetics is discussed. This study provides new insights into dendrite formation and paves the way for fast‐charging all‐solid‐state batteries.     

Amorphous Carbon Coated High Grain Boundary Density Dual Phase Li4Ti5O12‐TiO2: A Nanocomposite Anode Material for Li‐Ion Batteries

This work introduces an effective, inexpensive, and large‐scale production approach to the synthesis of a carbon coated, high grain boundary density, dual phase Li₄Ti₅O₁₂‐TiO₂ nanocomposite anode material for use in rechargeable lithium‐ion batteries. The microstructure and morphology of the Li₄Ti₅O₁₂‐TiO₂‐C product were characterized systematically. The Li₄Ti₅O₁₂‐TiO₂‐C nanocomposite electrode yielded good electrochemical performance in terms of high capacity (166 mAh g^?1 at a current density of 0.5 C), good cycling stability, and excellent rate capability (110 mAh g^?1 at a current density of 10 C up to 100 cycles). The likely contributing factors to the excellent electrochemical performance of the Li₄Ti₅O₁₂‐TiO₂‐C nanocomposite could be related to the improved morphology, including the presence of high grain boundary density among the nanoparticles, carbon layering on each nanocrystal, and grain boundary interface areas embedded in a carbon matrix, where electronic transport properties were tuned by interfacial design and by varying the spacing of interfaces down to the nanoscale regime, in which the grain boundary interface embedded carbon matrix can store electrolyte and allows more channels for the Li+ ion insertion/extraction reaction. This research suggests that carbon‐coated dual phase Li₄Ti₅O₁₂‐TiO₂ nanocomposites could be suitable for use as a high rate performance anode material for lithium‐ion batteries.     

Ultrathin Li4Ti5O12 Nanosheet Based Hierarchical Microspheres for High‐Rate and Long‐Cycle Life Li‐Ion Batteries

Ultrathin Li₄Ti₅O₁₂ nanosheet based hierarchical microspheres are synthesized through a three‐step hydrothermal procedure. The average thickness of the Li₄Ti₅O₁₂ sheets is only ≈(6.6 ± 0.25) nm and the specific surface area of the sample is 178 m² g^?1. When applied into lithium ion batteries as anode materials, the hierarchical Li₄Ti₅O₁₂ microspheres exhibit high specific capacities at high rates (156 mA h g^?1 at 20 C, 150 mA h g^?1 at 50 C) and maintain a capacity of 126 mA h g^?1 after 3000 cycles at 20 C. The results clearly suggest that the utility of hierarchical structures based on ultrathin nanosheets can promote the lithium insertion/extraction reactions in Li₄Ti₅O₁₂. The obtained hierarchical Li₄Ti₅O₁₂ with ultrathin nanosheets and large specific surface area can be perfect anode materials for the lithium ion batteries applied in high power facilities, such as electric vehicles and hybrid electric vehicles.     

Conductive Copper Niobate: Superior Li+‐Storage Capability and Novel Li+‐Transport Mechanism

Niobates with shear ReO₃ crystal structures are remarkably promising anode materials for Li⁺ batteries due to their large capacities, inherent safety, and high cycling stability. However, they generally suffer from limited rate capabilities rooted in their insufficient electronic and Li⁺ conductivities. Here, micrometer‐sized copper niobate (Cu₂Nb₃₄O₈₇) bulk as a new anode material having a high electronic conductivity of 2.1 × 10^?5 S cm^?1 and an impressive average Li⁺ diffusion coefficient of ≈3.5 × 10^?13 cm² s^?1 is exploited, which synergistically leads to an excellent rate capability (184 mAh g^?1 at 10 C) while remaining a large reversible capacity and superior cycling stability. Moreover, the fast Li⁺ transport pathways of grain boundary (micrometer scale) → lattice deformation area (nanometer scale) → (010) crystallographic plane (angstrom scale) are demonstrated in Cu₂Nb₃₄O₈₇. Therefore, these results could pave the way for practical application of Cu₂Nb₃₄O₈₇ in high‐performance Li⁺ batteries.     

High Reversible Lithium Storage Capacity and Structural Changes of Fe2O3 Nanoparticles Confined inside Carbon Nanotubes

The structural evolution of electrochemically prelithiated Fe₂O₃ nanoparticles confined in carbon nanotubes (CNTs) during lithium insertion/extraction is studied by in situ transmission electron microscopy. It is found that the aggregation and coarsening of Fe core‐containing Li₂O (Fe@Li₂O) nanograins formed during the charge process are prevented by the spatial restriction of the CNTs. A high reversible capacity of 2071 mA h g^?1 for the encapsulated Fe₂O₃ nanoparticles in CNTs is demonstrated when the material is used as the anode of lithium ion batteries. This is the highest reversible capacity ever reported for an Fe₂O₃ electrode. The significantly improved lithium storage capacity of the Fe₂O₃ nanoparticles is attributed to the extra lithium storage due to the enhanced interfacial lithium storage and reversible reaction of LiOH to form LiH and solid‐electrolyte‐interphase conversion originating from the nanoconfinement of CNTs as well as the very small particle size of the Fe@Li₂O nanograins and their good electrical contact with CNTs.     

A Robust Route to Co2(OH)2CO3 Ultrathin Nanosheets with Superior Lithium Storage Capability Templated by Aspartic Acid‐Functionalized Graphene Oxide

Two‐dimensional (2D) nanomaterials are widely recognized as an important class of functional materials possessing superior electrochemical reaction kinetics. Herein, an L‐aspartic acid (AA)‐modified graphene oxide (GO) templating strategy is developed to in situ yield ultrathin (i.e., ≈5 nm) cobalt carbonate hydroxide (Co₂(OH)₂CO₃) nanosheets as advanced anode materials of lithium ion batteries. Notably, the covalent tethering of AA on the GO surface renders a high density of carboxyl groups that impart effective loading of Co‐containing precursors and subsequent growth into Co₂(OH)₂CO₃ nanosheets bridging adjacent GO layers. The lasagna‐like Co₂(OH)₂CO₃‐GO nanocomposites exhibit an ultrahigh lithium storage capacity of 1770 mAh g^?1 after 500 cycles at 100 mA g^?1. It is noteworthy that the cycled Co₂(OH)₂CO₃ phase separates into homogeneously dispersed Co(OH)₂ and CoCO₃ phases with two different charge plateaus at ≈1.2 and 2.0 V, respectively, which effectively inhibit large‐scale homophase coarsening of Co, Li₂CO₃, and LiOH. The much shortened Li⁺/e^? transfer distance enabled by individual ultrathin Co₂(OH)₂CO₃ nanosheet together with robust layer‐by‐layer assembled nanostructure of Co₂(OH)₂CO₃‐GO confers the superior electrochemical reactivity and mechanical stability. As such, the amino acid‐modified GO templating strategy may represent a simple yet robust means of crafting a variety of 2D nanostructured composites of interest for energy storage applications.     

Advanced Energy‐Storage Architectures Composed of Spinel Lithium Metal Oxide Nanocrystal on Carbon Textiles

Current battery technologies are known to suffer from kinetic problems associated with the solid‐state diffusion of Li⁺ in intercalation electrodes materials. Not only the use of nanostructure materials but also the design of electrode architectures can lead to more advanced properties. Here, advanced electrode architectures consisting of carbon textiles conformally covered by Li₄Ti₅O₁₂ nanocrystal are rationally designed and synthesized for lithium ion batteries. The efficient two‐step synthesis involves the growth of ultrathin TiO₂ nanosheets on carbon textiles, and subsequent conversion into spinel Li₄Ti₅O₁₂ through chemical lithiation. Importantly, this novel approach is simple and general, and it is used to successfully produce LiMn₂O₄/carbon composites textiles, one of the leading cathode materials for lithium ion batteries. The resulting 3D textile electrode, with various advantages including the direct electronic pathway to current collector, the easy access of electrolyte ions, the reduced Li⁺/e^? diffusion length, delivers excellent rate capability and good cyclic stability over the Li‐ion batteries of conventional configurations.     

An Ultrastable Presodiated Titanium Disulfide Anode for Aqueous “Rocking‐Chair” Zinc Ion Battery

Rechargeable aqueous Zn‐based batteries are attractive candidates as energy storage technology, but the uncontrollable Zn dendrites, low stripping/plating coulombic efficiency, and inefficient utilization of Zn metal limit the battery reliability and energy density. Herein, for the first time, a novel presodiated TiS₂ (Na_0.14TiS₂) is proposed and investigated as an intercalated anode for aqueous Zn‐ion batteries, showing a capacity of 140 mAh g^?1 with a suitable potential of 0.3 V (vs Zn²⁺/Zn) at 0.05 A g^?1 and superior cyclability of 77% retention over 5000 cycles at 0.5 A g^?1. The remarkable performance originates from the buffer phase formation of Na_0.14TiS₂ after chemically presodiating TiS₂, which not only improves the structural reversibility and stability but also enhances the diffusion coefficient and electronic conductivity, and lowers cation migration barrier, as evidenced by a series of experimental and theoretical studies. Moreover, an aqueous “rocking‐chair” Zn‐ion full battery is successfully demonstrated by this Na_0.14TiS₂ anode and ZnMn₂O₄ cathode, which delivers a capacity of 105 mAh g^?1 (for anode) with an average voltage of 0.95 V at 0.05 A g^?1 and preserves 74% retention after 100 cycles at 0.2 A g^?1, demonstrating the feasibility of Zn‐ion full batteries for energy storage applications.     

Mesoporous TiO2‐Sn/C Core‐Shell Nanowire Arrays as High‐Performance 3D Anodes for Li‐Ion Batteries

Three‐dimensional mesoporous TiO₂‐Sn/C core‐shell nanowire arrays are prepared on Ti foil as anodes for lithium‐ion batteries. Sn formed by a reduction of SnO₂ is encapsulated into TiO₂ nanowires and the carbon layer is coated onto it. For additive‐free, self‐supported anodes in Li‐ion batteries, this unique core‐shell composite structure can effectively buffer the volume change, suppress cracking, and improve the conductivity of the electrode during the discharge‐charge process, thus resulting in superior rate capability and excellent long‐term cycling stability. Specifically, the TiO₂‐Sn/C nanowire arrays display rechargeable discharge capacities of 769, 663, 365, 193, and 90 mA h g^?1 at 0.1C, 0.5C, 2C 10C, and 30C, respectively (1C = 335 mA g^?1). Furthermore, the TiO₂‐Sn/C nanowire arrays exhibit a capacity retention rate of 84.8% with a discharge capacity of over 160 mA h g^?1, even after 100 cycles at a high current rate of 10C.     

A High‐Rate and Ultrastable Sodium Ion Anode Based on a Novel Sn4P3‐P@Graphene Nanocomposite

Phosphorus and tin phosphide based materials that are extensively researched as the anode for Na‐ion batteries mostly involve complexly synthesized and sophisticated nanocomposites limiting their commercial viability. This work reports a Sn₄P₃‐P (Sn:P = 1:3) @graphene nanocomposite synthesized with a novel and facile mechanochemical method, which exhibits unrivalled high‐rate capacity retentions of >550 and 371 mA h g^?1 at 1 and 2 A g^?1, respectively, over 1000 cycles and achieves excellent rate capability (>815, ≈585 and ≈315 mA h g^?1 at 0.1, 2, and 10 A g^?1, respectively).     

Polysulfide‐Shuttle Control in Lithium‐Sulfur Batteries with a Chemically/Electrochemically Compatible NaSICON‐Type Solid Electrolyte

A NaSICON‐type Li⁺‐ion conductive membrane with a formula of Li_{1+ x} Y _x Zr_{2? x} (PO₄)₃ (LYZP) (x = 0–0.15) has been explored as a solid‐electrolyte/separator to suppress polysulfide‐crossover in lithium‐sulfur (Li‐S) batteries. The LYZP membrane with a reasonable Li⁺‐ion conductivity shows both favorable chemical compatibility with the lithium polysulfide species and exhibits good electrochemical stability under the operating conditions of the Li‐S batteries. Through an integration of the LYZP solid electrolyte with the liquid electrolyte, the hybrid Li‐S batteries show greatly enhanced cyclability in contrast to the conventional Li‐S batteries with the porous polymer (e.g., Celgard) separator. At a rate of C/5, the hybrid Li ||LYZP|| Li₂S₆ batteries developed in this study (with a Li‐metal anode, a liquid/LYZP hybrid electrolyte, and a dissolved lithium polysulfide cathode) delivers an initial discharge capacity of ≈1000 mA h g^?1 (based on the active sulfur material) and retains ≈90% of the initial capacity after 150 cycles with a low capacity fade‐rate of <0.07% per cycle.     

Molecular Engineering of Monodisperse SnO2 Nanocrystals Anchored on Doped Graphene with High‐Performance Lithium/Sodium‐Storage Properties in Half/Full Cells

The fabrication of ultrasmall and high‐content SnO₂ nanocrystals anchored on doped graphene can endow SnO₂ with superior electrochemical properties. Herein, an effective strategy, involving molecular engineering of a layer‐by‐layer assembly technique, is proposed to homogeneously anchor SnO₂ nanocrystals on nitrogen/sulfur codoped graphene (NSGS), which serves as an advanced anode material in lithium/sodium‐ion batteries (LIBs/SIBs). Benefiting from novel design and specific structure, the optimized NSGS for LIBs displays high initial capacity (2123.9 mAh g^?1 at 0.1 A g^?1), long‐term cycling performance (only 0.8% loss after 500 cycles), and good rate capability (477.4 mAh g^?1 at 5 A g^?1). In addition, the optimized NSGS for SIBs also delivers high initial capacity (791.7 mAh g^?1 at 0.1 A g^?1) and high reversible capacity (180.2 mAh g^?1 after 500 cycles at 0.5 A g^?1). Meanwhile, based on the detailed analysis of phase transition and electrochemical reaction kinetics, the reaction mechanisms of NSGS in LIBs and SIBs as well as the distinction in LIBs/SIBs are clearly articulated. Notably, to further explore the practical application, Li/Na⁺ full cells are also assembled by coupling the optimized NSGS anode with LiCoO₂ and Na₃V₂(PO₄)₃/C cathodes, respectively.     

Metal Sulfide‐Decorated Carbon Sponge as a Highly Efficient Electrocatalyst and Absorbant for Polysulfide in High‐Loading Li2S Batteries

Owing to its high theoretical specific capacity (1166 mA h g^?1) and particularly its advantage to be paired with a lithium‐metal‐free anode, lithium sulfide (Li₂S) is regarded as a much safer cathode for next‐generation advanced lithium–sulfur (Li–S) batteries. However, the low conductivity of Li₂S and particularly the severe “polysulfide shuttle” of lithium polysulfide (LiPS) dramatically hinder their practical application in Li–S batteries. To address such issues, herein a bifuctional 3D metal sulfide‐decorated carbon sponge (3DTSC), which is constructed by 1D carbon nanowires cross‐linked with 2D graphene nanosheets with high conductivity and polar 0D metal sulfide nanodots with efficient electrocatalytic activity and strong chemical adsorption capability for LiPSs, is presented. Benefiting from the well‐designed multiscale, multidimensional 3D porous nanoarchitecture with high conductivity, and efficient electrocatalytic and absorption ability, the 3DTSC significantly mitigates LiPS shuttle, improves the utilization of Li₂S, and facilitates the transport of electrons and ions. As a result, even with a high Li₂S loading of 8 mg cm^?2, the freestanding 3DTSC‐Li₂S cathode without a polymer binder and metallic current collector delivers outstanding electrochemical performance with a high areal capacity of 8.44 mA h cm^?2.     

Tailored Plum Pudding‐Like Co2P/Sn Encapsulated with Carbon Nanobox Shell as Superior Anode Materials for High‐Performance Sodium‐Ion Capacitors

Sodium‐ion capacitors (SICs) are emerging energy storage devices with high energy, high power, and durable life. Sn is a promising anode material for lithium storage, but the poor conductivity of the a‐NaSn phase upon sodaition hinders its implementation in SICs. Herein, a superior Sn‐based anode material consisting of plum pudding‐like Co₂P/Sn yolk encapsulated with nitrogen‐doped carbon nanobox (Co₂P/Sn@NC) for high‐performance SICs is reported. The 8–10 nm metallic nanoparticles produced in situ are uniformly dispersed in the amorphous Sn matrix serving as conductive fillers to facilitate electron transfer in spite of the formation of electrically resistive a‐NaSn phase during cycling. Meanwhile, the carbon shell buffers the large expansion of active Sn and provides a stable electrode–electrolyte interface. Owing to these merits, the yolk–shell Co₂P/Sn@NC demonstrates a large capacity of 394 mA h g^?1 at 100 mA g^?1, high rate capability of 168 mA h g^?1 at 5000 mA g^?1, and excellent cyclability with 87% capacity retention after 10 000 cycles. By integrating the Co₂P/Sn@NC anode with a peanut shell‐derived carbon cathode in the SIC, high energy densities of 112.3 and 43.7 Wh kg^?1 at power densities of 100 and 10 000 W kg^?1 are achieved.