Prestoring Lithium into Stable 3D Nickel Foam Host as Dendrite‐Free Lithium Metal Anode

Lithium metal is considered a “Holy Grail” of anode materials for high‐energy‐density batteries. However, both dendritic lithium deposition and infinity dimension change during long‐term cycling have extremely restricted its practical applications for energy storage devices. Here, a thermal infusion strategy for prestoring lithium into a stable nickel foam host is demonstrated and a composite anode is achieved. In comparison with the bare lithium, the composite anode exhibits stable voltage profiles (200 mV at 5.0 mA cm^?2) with a small hysteresis beyond 100 cycles in carbonate‐based electrolyte, as well as high rate capability, significantly reduced interfacial resistance, and small polarization in a full‐cell battery with Li₄Ti₅O₁₂ or LiFePO₄ as counter electrode. More importantly, in addition to the fact that lithium is successfully confined in the metallic nickel foam host, uniform lithium plating/stripping is achieved with a low dimension change (merely ≈3.1%) and effective inhibition of dendrite formation. The mechanism for uniform lithium stripping/plating behavior is explained based on a surface energy model.     

Spatially Controlled Lithium Deposition on Silver-Nanocrystals-Decorated TiO2 Nanotube Arrays Enabling Ultrastable Lithium Metal Anode

3D scaffolds and heterogeneous seeds are two effective ways to guide Li deposition and suppress Li dendrite growth. Herein, 3D TiO₂ nanotube (TNT) arrays decorated using ultrafine silver nanocrystals (7–10 nm) through cathodic reduction deposition are first demonstrated as a confined space host for lithium metal deposition. First, TiO₂ possesses intrinsic lithium affinity with large Li absorption energy, which facilitates Li capture. Then, ultrafine silver nanocrystals decoration allows the uniform and selective nucleation in nanoscale without a nucleation barrier, leading to the extraordinary formation of lithium metal importing into 3D nanotube arrays. As a result, Li metal anode deposited on such a binary architecture (TNT-Ag-Li) delivers a high Coulomb efficiency at around 99.4% even after 300 cycles with a capacity of 2 mA h cm⁻². Remarkably, TNT-Ag-Li exhibits ultralow overpotential of 4 mV and long-term cycling life over 2500 h with a capacity of 2 mAh cm^–2 in Li symmetric cells. Moreover, the full battery with 3D spaced Li nanotubes anode and LiFeO₄ cathode exhibits a stable and high capacity of 115 mA h g^–1 at 5 C and an excellent Coulombic efficiency of ≈100% over 500 cycles.     

Lithiophilic MXene-Guided Lithium Metal Nucleation and Growth Behavior

The positive effects of a lithiophilic substrate on the electrochemical performance of lithium metal anodes are confirmed in several reports, while the understanding of lithiophilic substrate-guided lithium metal nucleation and growth behavior is still insufficient. In this study, the effect of a lithiophilic surface on lithium metal nucleation and growth behaviors is investigated using a large-area Ti₃C₂T_x MXene substrate with a large number of oxygen and fluorine dual heteroatoms. The use of the MXene substrate results in a high lithium-ion concentration as well as the formation of uniform solid–electrolyte-interface (SEI) layers on the lithiophilic surface. The solid–solid interface (MXene-SEI layer) significantly affects the surface tension of the deposited lithium metal nuclei as well as the nucleation overpotential, resulting in the formation of uniformly dispersed lithium nanoparticles ( ≈ 10–20 nm in diameter) over the entire MXene surface. The primary lithium nanoparticles preferentially coalesce and agglomerate into larger secondary particles while retaining their primary particle shapes. Subsequently, they form close-packed structures, resulting in a dense metal layer composed of particle-by-particle microstructures. This distinctive lithium metal deposition behavior leads to highly reversible cycling performance with high Columbic efficiencies >  99.0% and long cycle lives of over 1000 cycles.     

Lamellar MXene Composite Aerogels with Sandwiched Carbon Nanotubes Enable Stable Lithium–Sulfur Batteries with a High Sulfur Loading

Realizing long cycling stability under a high sulfur loading is an essential requirement for the practical use of lithium–sulfur (Li–S) batteries. Here, a lamellar aerogel composed of Ti₃C₂T_x MXene/carbon nanotube (CNT) sandwiches is prepared by unidirectional freeze-drying to boost the cycling stability of high sulfur loading batteries. The produced materials are denoted parallel-aligned MXene/CNT (PA-MXene/CNT) due to the unique parallel-aligned structure. The lamellae of MXene/CNT/MXene sandwich form multiple physical barriers, coupled with chemical trapping and catalytic activity of MXenes, effectively suppressing lithium polysulfide (LiPS) shuttling under high sulfur loading, and more importantly, substantially improving the LiPS confinement ability of 3D hosts free of micro- and mesopores. The assembled Li–S battery delivers a high capacity of 712 mAh g⁻¹ with a sulfur loading of 7 mg cm⁻², and a superior cycling stability with 0.025% capacity decay per cycle over 800 cycles at 0.5 C. Even with sulfur loading of 10 mg cm⁻², a high areal capacity of above 6 mAh cm⁻² is obtained after 300 cycles. This work presents a typical example for the rational design of a high sulfur loading host, which is critical for the practical use of Li–S batteries     

Composite Lithium Metal Anodes with Lithiophilic and Low-Tortuosity Scaffold Enabling Ultrahigh Currents and Capacities in Carbonate Electrolytes

The practical application of lithium metal anode has been hindered by safety and cyclability issues due to the uncontrollable dendrite growth, especially during fast cycling and deep plating/stripping process. Here, a composite Li metal anode supported by periodic, perpendicular, and lithiophilic TiO₂/poly(vinyl pyrrolidone) (PVP) nanofibers via a facial rolling process is reported. TiO₂/PVP nanofibers with good Li affinity provide low-tortuosity and directly inward Li⁺ transport paths to facilitate Li nucleation and deposition under high areal capacities and current densities. The micrometer-scale interspaces between TiO₂/PVP walls offer enough space to circumvent the huge volume variation and avoid structure collapsing during the repeated deep Li plating/stripping. The unique structure enables stable cycling under ultrahigh currents (12 mA cm⁻²), and ultra-deep plating/stripping up to 60 mAh cm⁻² with a long cycle life in commercial carbonate electrolytes. The gassing behavior in operating pouch cells is observed using ultrasonic transmission mapping. When paired with LiFePO₄ (5 mAh cm⁻²), sulfur (3 mAh cm⁻²), and high-voltage LiNi_0.8Co_0.1Mn_0.1O₂ cathodes, the composite Li anodes deliver remarkably improved rate performance and cycling stability, demonstrating that it could be a promising strategy for balancing high-energy density and high-power density in Li metal batteries.     

Lithiation MXene Derivative Skeletons for Wide-Temperature Lithium Metal Anodes

Lithium (Li) metal, as an appealing candidate for the next-generation of high-energy-density batteries, is plagued by its safety issue mainly caused by uncontrolled dendrite growth and infinite volume expansion. Developing new materials that can improve the performance of Li-metal anode is one of the urgent tasks. Herein, a new MXene derivative containing pure rutile TiO₂ and N-doped carbon prepared by heat-treating MXene under a mixing gas, exhibiting high chemical activity in molten Li, is reported. The lithiation MXene derivative with a hybrid of LiTiO₂-Li₃N-C and Li offers outstanding electrochemical properties. The symmetrical cell assembling lithiation MXene derivative hybrid anode exhibits an ultra-long cycle lifespan of 2000 h with an overpotential of ≈30 mV at 1 mA cm⁻², which overwhelms Li-based anodes reported so far. Additionally, long-term operations of 34, 350, and 500 h at 10 mA cm⁻² can be achieved in symmetrical cells at temperatures of −10, 25, and 50 °C, respectively. Both experimental tests and density functional theory calculations confirm that the LiTiO₂-Li₃N-C skeleton serves as a promising host for Li infusion by alleviating volume variation. Simultaneously, the superlithiophilic interphase of Li₃N guides Li deposition along the LiTiO₂-Li₃N-C skeleton to avoid dendrite growth.     

Pillared MXene with Ultralarge Interlayer Spacing as a Stable Matrix for High Performance Sodium Metal Anodes

Sodium (Na) metal is a promising alternative to lithium metal as an anode material for the next‐generation energy storage systems due to its high theoretical capacity, low cost, and natural abundance. However, dendritic/mossy Na growth caused by uncontrollable plating/stripping results in serious safe concerns and rapid electrode degradation. This study presents Sn²⁺ pillared Ti₃C₂ MXene serving as a stable matrix for high‐performance dendrite‐free Na metal anode. The intercalated Sn²⁺ between Ti₃C₂ layers not only induces Na to nucleate and grow within Ti₃C₂ interlayers, but also endows the Ti₃C₂ with larger interlayer space to accommodate the deposited Na by taking advantage of the “pillar effect,” contributing to uniform Na deposition. As a result, the pillar‐structured MXene‐based Na metal electrode could enable high current density (up to 10 mA cm^?2) along with high areal capacity (up to 5 mAh cm^?2) over long‐term cycling (up to 500 cycles). The full cell using MXene‐based Na metal anode exhibits superior electrochemical performance than that using host‐less commercial Na. It is believed that the well‐controlled MXene‐based Na anode not only extends the application scope of MXene, but also provides guidance in designing high‐performance Na metal batteries.     

Lithiophilic Mo2C Clusters-Embedded Carbon Nanofibers for High Energy Density Lithium Metal Batteries

Lithium metal anodes are widely regarded as the ideal candidate for the next generation of high-energy-density lithium batteries. Here, a 3D host made of lithiophilic Mo₂C clusters-embedded carbon nanofibers (Mo₂C@CNF) is developed. The uniformly dispersed clusters and large specific surface areas of Mo₂C@CNF provide numerous nucleation sites for lithium deposition. Mo₂C clusters exhibit ultralow nucleation overpotential compared to MoO₂, which is also supported by density functional theory calculations. Furthermore, the transition metal element serves as a catalyst for the formation of a stable and robust solid electrolyte interphase layer containing LiF on Mo₂C@CNF, effectively mitigating the occurrence of dead lithium and enhancing the Coulombic efficiency during prolonged operation. As a result, the Mo₂C@CNF composite delivers superior electrochemical performance (>1600 h) at 1 mA cm⁻² and lower nucleation overpotential (13 mV) for lithium plating. The Li/Mo₂C@CNF anode coupled with the commercial LiFePO₄ cathode exhibits excellent cycling stability (300 cycles at 1 C) and high rate capability at low N/P ratios.     

Dendrite-Free Reverse Lithium Deposition Induced by Ion Rectification Layer toward Superior Lithium Metal Batteries

Considerable endeavors are developed to suppress lithium (Li) dendrites and improve the cycling stability of Li metal batteries in order to promote their commercial application. Herein, continuous zinc (Zn) nanoparticles-assembled film with homogenous nanopores is proposed as a modified layer for separator via a scalable method. The in situ formed LiZn alloy film during initial Li plating can serve as a Li⁺ ion rectification and lithiophilic layer to regulate the nucleation and reverse deposition of Li. When applied in Li|LiFePO₄ full cells with traditional carbonate-based electrolyte, the modified separator enables outstanding cycling stability of up to 350 cycles without capacity loss at a large rate of 5 C (3.4 mA cm⁻²) and a remarkable reversible capacity of 144 mAh g⁻¹ after 120 cycles at a commercial mass loading as high as 19.72 mg cm⁻². The excellent electrochemical performances are ascribed to the dendrite-free reverse Li deposition induced by modified layer by means of its lithiophilic property for regulating homogeneous Li nucleation on the separator as well as its well-distributed nanopores for homogenizing Li⁺ ion flux and enhancing electrolyte wetting.     

Nanoflake Arrays of Lithiophilic Metal Oxides for the Ultra‐Stable Anodes of Lithium‐Metal Batteries

A molten lithium infusion strategy has been proposed to prepare stable Li‐metal anodes to overcome the serious issues associated with dendrite formation and infinite volume change during cycling of lithium‐metal batteries. Stable host materials with superior wettability of molten Li are the prerequisite. Here, it is demonstrated that a series of strong oxidizing metal oxides, including MnO₂, Co₃O₄, and SnO₂, show superior lithiophilicity due to their high chemical reactivity with Li. Composite lithium‐metal anodes fabricated via melt infusion of lithium into graphene foams decorated by these metal oxide nanoflake arrays successfully control the formation and growth of Li dendrites and alleviate volume change during cycling. A resulting Li‐Mn/graphene composite anode demonstrates a super‐long and stable lifetime for repeated Li plating/stripping of 800 cycles at 1 mA cm^?2 without voltage fluctuation, which is eight times longer than the normal lifespan of a bare Li foil under the same conditions. Furthermore, excellent rate capability and cyclability are realized in full‐cell batteries with Li‐Mn/graphene composite anodes and LiCoO₂ cathodes. These results show a major advancement in developing a stable Li anode for lithium‐metal batteries.     

Porosity‐ and Graphitization‐Controlled Fabrication of Nanoporous Silicon@Carbon for Lithium Storage and Its Conjugation with MXene for Lithium‐Metal Anode

Silicon (Si) and lithium metal are the most favorable anodes for high‐energy‐density lithium‐based batteries. However, large volume expansion and low electrical conductivity restrict commercialization of Si anodes, while dendrite formation prohibits the applications of lithium‐metal anodes. Here, uniform nanoporous Si@carbon (NPSi@C) from commercial alloy and CO₂ is fabricated and tested as a stable anode for lithium‐ion batteries (LIBs). The porosity of Si as well as graphitization degree and thickness of the carbon layer can be controlled by adjusting reaction conditions. The rationally designed porosity and carbon layer of NPSi@C can improve electronic conductivity and buffer volume change of Si without destroying the carbon layer or disrupting the solid electrolyte interface layer. The optimized NPSi@C anode shows a stable cyclability with 0.00685% capacity decay per cycle at 5 A g^?1 over 2000 cycles for LIBs. The energy storage mechanism is explored by quantitative kinetics analysis and proven to be a capacitance‐battery dual model. Moreover, a novel 2D/3D structure is designed by combining MXene and NPSi@C. As lithiophilic nucleation seeds, NPSi@C can induce uniform Li deposition with buffered volume expansion, which is proven by exploring Li‐metal deposition morphology on Cu foil and MXene@NPSi@C. The practical potential application of NPSi@C and MXene@NPSi@C is evaluated by full cell tests with a Li(Ni_0.8Co_0.1Mn_0.1)O₂ cathode.     

Spherical Lithium Deposition Enables High Li-Utilization Rate,Low Negative/Positive Ratio,and High Energy Density in Lithium Metal Batteries

Lithium metal battery promises an attractively high energy density. A high Li-utilization rate of Li metal anode is the prerequisite for the high energy density and avoiding a huge waste of the Li resource. However, the dendritic Li deposition gives rise to “dead Li” and parasitic interfacial reactions, resulting in a low Li utilization rate. Herein, Li deposition is regulated to spherical Li by designing an MXene host with an egg-box structure, suitable curvature, and continuous gradient lithiophilic structure. Because the spherical Li greatly reduces the interfacial side reactions and avoids the formation of dead Li, the Li anode affords a high plating/stripping efficiency. Furthermore, the gradient lithiophilic design results in a bottom-up growth of the spherical Li within the host, safely away from the separator. Thus, the spherical Li anode realizes a long life of >3000 h with a high Li-utilization rate of >90%, stable cycling in full cells at an areal capacity up to 5 mAh cm⁻² with a low negative/positive ratio of 0.8, which is critical for high energy density. Such spherical deposition highlights the critical role of the morphological control of alkali metals and provides a viable method to build practical high-energy metal batteries.     

Regulating Uniform Li Plating/Stripping via Dual‐Conductive Metal‐Organic Frameworks for High‐Rate Lithium Metal Batteries

Lithium metal anodes show immense scope for application in high‐energy electronics and electric vehicles. Unfortunately, lithium dendrite growth and volume change leading to short lifespan and safety issues severely limit the feasibility of lithium metal batteries. A rational design of metal–organic framework (MOF)‐modified Li metal anode with optimized Li plating/stripping behavior via one‐step carbonization of ZIF‐67 is proposed. Experimental and theoretical simulation results reveal that carbonized MOFs with uniformly dispersed Co nanoparticles in N‐graphene (Co@N‐G) exhibit an electronic/ionic dual‐conductivity and significantly improved affinity with Li, and so serve as an ideal host for dendrite‐free lithium deposition, consequently leading to uniform lithium plating/stripping during cycling. As a result, the anode delivers highly stable cyclic performance with high coulombic efficiency (CE) at ultrahigh current densities (CE = 91.5% after 130 cycles at 10 mA cm^?2, and CE = 90.4% after 80 cycles at 15 mA cm^?2). Moreover, the practical applicability and functionality of such anodes are demonstrated through assembly of Li‐Co@N‐G/NCM full batteries exhibiting a long cycle life of 100 cycles with a high capacity retention of 92% at 1 C.     

Superionic Conductor Enabled Composite Lithium with High Ionic Conductivity and Interfacial Wettability for Solid-State Lithium Batteries

The urgent demand for high energy and safety batteries has generated the rapid development of Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO) type solid-state lithium metal batteries. However, severe dendritic lithium growth, which is caused by poor interfacial contact of the Li/LLZTO interface and loss of electrical contact during cycles due to low intrinsic Li⁺ diffusion coefficient of lithium, greatly hampers its practical application. Here, from the point of view of reducing surface tension and improving ion diffusion of lithium, a composite lithium anode (CLA) with high wettability and ion diffusion coefficient is prepared by adding GaP into molten lithium, thus strengthening the CLA/LLZTO interface even in cycling. As envisioned, compared to pure lithium, CLA presents lower surface tension, larger adhesion work, and higher ion diffusion coefficient, ensuring close contact of the CLA/LLZTO interface. Therefore, the assembled symmetric cells exhibit a low area specific resistance of 4.5 Ω cm², a large critical current density of 2.5 mA cm⁻², and ultra-long lifespan of 5700 h at 0.3 mA cm⁻² at 25 °C. Meanwhile, full cells coupled with LiFePO₄ cathode show a high-capacity retention of 97.32% after 490 cycles at 1C. This work provides a new solution to the interfacial challenges of solid-state lithium-metal batteries.     

Perpendicular MXene Arrays with Periodic Interspaces toward Dendrite‐Free Lithium Metal Anodes with High‐Rate Capabilities

Although lithium metal is an ultimate anode material for lithium‐based batteries owing to its high theoretical capacity, the uncontrollable dendrites and infinite volume change associated with poor rate capabilities are stagnating its practical applications. Here, a new type of perpendicular MXene–Li array is developed with tunable MXene walls and constant space in between as anodes for lithium metal batteries. Such perpendicular MXene arrays possess dual periodic interspaces, i.e., nanometer‐scale interspaces in MXene walls and micrometer‐scale interspaces between MXene walls. The former interspaces are favorable for the fast transfer of lithium ions upon stripping and plating, and the latter enables efficiently homogenization of the electric field, leading to a good high‐rate capability up to 20 mA cm^?2. More importantly, the notorious lightning rod effect and volume change are efficiently inhibited in such perpendicular MXene arrays, giving rise to a dendrite‐free lithium anode with a low potential of 25 mV, a high capacity of 2056 mAh g^?1, and good cycle stability up to 1700 h.     

Van der Waals Forces between S and P Ions at the CoP-C@MoS2/C Heterointerface with Enhanced Lithium/Sodium Storage

Metal–organic framework-derived metal phosphides with high capacity, facile synthesis, and morphology-controlled are considered as potential anodes for lithium/sodium-ion batteries. However, the severe volume expansion during cycling can cause the electrode material to collapse and reduce the cycle life. Here, novel CoP-C@MoS₂/C nanocube composites are synthesized by vapor-phase phosphating and hydrothermal process. As the anode of LIBs, CoP-C@MoS₂/C exhibits outstanding long-cycle performance of 369 mAh g⁻¹ at 10 A g⁻¹ after 2000 cycles. In SIBs, the composite also displays excellent rate capability of 234 mAh g⁻¹ at 5 A g⁻¹ and an ultra-high the capacity retention rate of 90.16% at 1 A g⁻¹ after 1000 cycles. Through density functional theory, it is found that the S ions and P ions at the interface formed by CoP and MoS₂ can serve as Na⁺/Li⁺ diffusion channels with an action of van der Waals force, have attractive characteristics such as high ion adsorption energy, low expansion rate and fast diffusion kinetics compared with MoS₂. This study provides enlightenment for the reasonable design and development of lithium/sodium storage anode materials composited with MOF-derived metal phosphides and metal sulfides.     

Overcoming Anode Instability in Solid-State Batteries through Control of the Lithium Metal Microstructure

Enabling the lithium metal anode (LMA) in solid-state batteries (SSBs) is the key to developing high energy density battery technologies. However, maintaining a stable electrode–electrolyte interface presents a critical challenge to high cycling rate and prolonged cycle life. One such issue is the interfacial pore formation in LMA during stripping. To overcome this, either higher stack pressure or binary lithium alloy anodes are used. Herein, it is shown that fine-grained (d = 20 µm) polycrystalline LMA can avoid pore formation by exploiting the microstructural dependence of the creep rates. In a symmetric cell set-up, i.e., LiǀLi_6.25Al_0.25La₃Zr₂O₁₂(LLZO)ǀLi, fine-grained LMA achieves > 11.0 mAh cm⁻² compared to ≈ 3.6 mAh cm⁻² for coarse-grained LMA (d = 295 µm) at 0.1 mA cm⁻² and at moderate stress of 2.0 MPa. Smaller diffusion lengths (≈ 20 µm) and higher diffusivity pathway along dislocations (D_d ≈ 10⁻⁷ cm² s⁻¹), generated during cell fabrication, result in enhanced viscoplastic deformation in fine-grained polycrystalline LMA. The electrochemical performances corroborate well with estimated creep rates. Thus, microstructural control of LMA can significantly reduce the required stack pressure during stripping. These results are particularly relevant for “anode-free” SSBs wherein both the microstructure and the mechanical state of the lithium are critical parameters.     

A Periodic “Self‐Correction” Scheme for Synchronizing Lithium Plating/Stripping at Ultrahigh Cycling Capacity

Lithium (Li) metal can deliver the highest theoretical specific capacity among all lithium battery anodes, yet its application is significantly hindered due to a series of critical challenges (poor cycleability and safety risks, etc.), most of which are related to uncontrolled Li dendrite growth. However, the dendrite problem cannot be fully avoided because of a number of complicated multi‐physical field factors, especially under high cycling rate and high capacity conditions. An ideal situation is when the battery can automatically restore the uncontrolled dendrites growth itself, whenever it appears during the entire cycling lifespan; however, discussion on this issue is rare. A periodically conductive/dielectric lamella scaffold is developed for hosting Li metal to realize a “self‐correction” functionality, which can automatically synchronize Li deposition/stripping by periodically re‐homogenizing electric field distribution around irregular Li protrusions. Consequently, dendrite‐free Li plating/stripping with high Coulombic efficiency can be achieved even at 5 mA cm^?2 and an ultrahigh cycling capacity of 15 mAh cm^?2. Notably, a maximal cumulative plating capacity of 4000 mAh cm^?2 with Li utilization of 50% is realized, outperforming most recently reported results. This work provides new insights for designing future smart high‐performance metal anode batteries for real application.     

High Areal Capacity Dendrite-Free Li Anode Enabled by Metal–Organic Framework-Derived Nanorod Array Modified Carbon Cloth for Solid State Li Metal Batteries

Li metal is one of the most promising anode materials for high energy density batteries. However, uncontrollable Li dendrite growth and infinite volume change during the charge/discharge process lead to safety issues and capacity decay. Herein, a carbonized metal–organic framework (MOF) nanorod arrays modified carbon cloth (NRA-CC) is developed for uniform Li plating/stripping. The carbonized MOF NRAs effectively convert the CC from lithiophobic to lithiophilic, decreasing the polarization and ensuring homogenous Li nucleation. The 3D interconnected hierarchal CC provides adequate Li nucleation sites for reducing the local current density to avoid Li dendrite growth, and broadens internal space for buffering the volume change during Li plating/stripping. These characteristics afford a stable cycling of the NRA-CC electrode with ultrahigh Coulombic efficiencies of 96.7% after 1000 h cycling at 2 mA cm⁻² and a prolonged lifespan of 200 h in the symmetrical cell under ultrahigh areal capacity (12 mAh cm⁻²) and current (12 mA cm⁻²). The solid-state batteries assembled with the composite Li anode, high-voltage cathode (LiNi_0.5Co_0.2Mn_0.3O₂), and composite solid-state electrolyte also deliver excellent cyclic and rate performance at 25 °C. This work sheds fresh insights on the design principles of a dendrite-free Li metal anode for safe solid-state Li metal batteries.     

Dendrite-Free and Long-Cycling Sodium Metal Batteries Enabled by Sodium-Ether Cointercalated Graphite Anode

Stable and dendrite-free Na metal plating–stripping is achieved on the graphite electrode. The sodium-ether cointercalated graphite exhibits ultrahigh Na deposition efficiency of 99.86% over 900 cycles at a current density of 2 mA cm⁻². The discharge process involves the [Na-ether]⁺ cointercalation and Na deposition. Density functional theory calculations demonstrate that the cointercalated graphite is critical for uniform Na deposition and stable Coulombic efficiency, which is ascribed to both the robust binding sites to Na by the diglyme molecules and a low lattice mismatch for Na growth on the cointercalated graphite. Also, a full cell consisting of Na₄Fe₃(PO₄)₂(P₂O₇) cathode and 0.5 mAh cm⁻² Na predeposited graphite anode shows excellent cycling stability. The full cell delivers a capacity of 95 mAh g⁻¹ based on the weight of cathode materials, with a high capacity retention of 91% over 300 cycles.