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.     

Engineering Wavy‐Nanostructured Anode Interphases with Fast Ion Transfer Kinetics: Toward Practical Li‐Metal Full Batteries

Fast Li‐metal depletion and severe anode pulverization are the most critical obstacles for the energy‐dense Li‐metal full batteries using thin Li‐metal anodes (<50 µm). Here, a wavy‐nanostructured solid electrolyte interphase (SEI) with fast ion transfer kinetics is reported, which can promote high‐efficiency Li‐metal plating/stripping (>98% at 4 mAh cm^?2) in conventional carbonate electrolyte. Cryogenic transmission electron microscopy (cryo‐TEM) further reveals the fundamental relationship between wavy‐nanostructured SEI, function, and the electrochemical performance. The wavy SEI with greatly decreased surface diffusion resistance can realize grain coarsening of Li‐metal deposition and exhaustive dissolution of active Li‐metal during the stripping process, which can effectively alleviate “dead Li” accumulation and anode pulverization problems in practical full cells. Under highly challenging conditions (45 µm Li‐metal anodes, 4.3 mAh cm^?2 high capacity LiNi_0.8Mn_0.1Co_0.1O₂ cathodes), full cells exhibit significantly improved cycling lifespan (170 cycles; 20 cycles for control cells) via the application of wavy SEI.     

A Soft Lithiophilic Graphene Aerogel for Stable Lithium Metal Anode

The lithium metal anode is one of the most promising anodes for next‐generation high‐energy‐density batteries. However, the severe growth of Li dendrites and large volume expansion leads to rapid capacity decay and shortened lifetime, especially in high current density and high capacity. Herein, a soft 3D Au nanoparticles@graphene hybrid aerogel (Au? GA) as a lithiophilic host for lithium metal anode is proposed. The large surface area and interconnected conductive pathways of the Au? GA significantly decrease the local current density of the electrode, enabling uniform Li deposition. Furthermore, the 3D porous structure effectively accommodates the large volume expansion during Li plating/stripping, and the Li_xAu alloy serves as a solid solution buffer layer to completely eliminate the Li nucleation over‐potential. Symmetric cells can stably cycle at 8 mA cm^?2 for 8 mAh cm^?2 and exhibit ultra‐long cycling: 1800 h at 2 mA cm^?2 for 2 mAh cm^?2, and 1200 h at 4 mA cm^?2 for 4 mAh cm^?2, with low over‐potential. Full cells assemble with a Cu@Au? GA? Li anode and LiFePO₄ cathode, can sustain a high rate of 8 C, and retain a high capacity of 59.6 mAh g^?1 after 1100 cycles at 2 C.     

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.     

Fluoroethylene Carbonate Additives to Render Uniform Li Deposits in Lithium Metal Batteries

Lithium (Li) metal has been considered as an important substitute for the graphite anode to further boost the energy density of Li‐ion batteries. However, Li dendrite growth during Li plating/stripping causes safety concern and poor lifespan of Li metal batteries (LMB). Herein, fluoroethylene carbonate (FEC) additives are used to form a LiF‐rich solid electrolyte interphase (SEI). The FEC‐induced SEI layer is compact and stable, and thus beneficial to obtain a uniform morphology of Li deposits. This uniform and dendrite‐free morphology renders a significantly improved Coulombic efficiency of 98% within 100 cycles in a Li | Cu half‐cell. When the FEC‐protected Li metal anode matches a high‐loading LiNi_0.5Co_0.2Mn_0.3O₂ (NMC) cathode (12 mg cm^?2), a high initial capacity of 154 mAh g^?1 (1.9 mAh cm^?2) at 180.0 mA g^?1 is obtained. This LMB with conversion‐type Li metal anode and intercalation‐type NMC cathode affords an emerging energy storage system to probe the energy chemistry of Li metal protection and demonstrates the material engineering of batteries with very high energy density.     

Dendrite-Free Li-Metal Anode Enabled by Dendritic Structure

The practical application of Li-metal anode in high-energy rechargeable Li batteries is still hindered by the uncontrollable formation of Li dendrites. Here, a facile way is reported to stabilize Li-metal anode by building dendrite-like Li₃Mg₇ alloys enriched with Li-containing polymers as the physical protecting layer and LiH as the Li-ion conductor. This unique dendritic structure effectively reduces local current density and accommodates volume change during the repeated Li plating/stripping process. More importantly, lithiophilic Li₃Mg₇ alloys not only guide the uniform Li deposition down into the below Li metal upon Li deposition, but also thermodynamically promote the extraction of Li during the reverse Li stripping process, which suppresses the parasitic reactions occurring on the surface of Li metal and hence inhibits the formation of Li dendrites. Moreover, the facile diffusion of Mg from Li₃Mg₇ alloys toward Li metal below is thermodynamically permitted, which leads to a uniform distribution of LiMg alloys inside the whole electrode and thus benefits long-term deep cycling stability. As a result, the protected Li-metal anode delivers stable and dendrite-free cycling performance at 10 mA h cm⁻² for over 900 h. When coupling this anode with LiFePO₄ and S cathodes, the thus-assembled full cells exhibit superior cycling stability.     

Vertically Aligned Carbon Nanofibers on Cu Foil as a 3D Current Collector for Reversible Li Plating/Stripping toward High‐Performance Li–S Batteries

A vertically aligned carbon nanofiber (VACNF) array with unique conically stacked graphitic structure directly grown on a planar Cu current collector (denoted as VACNF/Cu) is used as a high‐porosity 3D host to overcome the commonly encountered issues of Li metal anodes. The excellent electrical conductivity and highly active lithiophilic graphitic edge sites facilitate homogenous coaxial Li plating/stripping around each VACNF and forming a uniform solid electrolyte interphase. The high specific surface area effectively reduces the local current density and suppresses dendrite growth during the charging/discharging processes. Meanwhile, this open nanoscale vertical 3D structure eliminates the volume changes during Li plating/stripping. As a result, highly reversible Li plating/stripping with high coulombic efficiency is achieved at various current densities. A low voltage hysteresis of 35 mV over 500 h in symmetric cells is achieved at 1 mA cm^?2 with an areal Li plating capacity of 2 mAh cm^?2, which is far superior to the planar Cu current collector. Furthermore, a Li–S battery using a S@PAN cathode and a lithium‐plated VACNF/Cu (VACNF/Cu@Li) anode with slightly higher capacity (2 mAh cm^?2) exhibits an excellent rate capability and high cycling stability with no capacity fading over 600 cycles.     

A Mixed Lithium‐Ion Conductive Li2S/Li2Se Protection Layer for Stable Lithium Metal Anode

Constructing artificial solid‐electrolyte interphase (SEI) on the surface of Li metal is an effective approach to improve ionic conductivity of surface SEI and buffer Li dendrite growth of Li metal anode. However, constructing of homogenous ideal artificial SEI is still a great challenge. Here, a mixed lithium‐ion conductive Li₂S/Li₂Se (denoted as LSSe) protection layer, fabricated by a facile and inexpensive gas–solid reaction, is employed to construct stable surface SEI with high ionic conductivity. The Li₂S/Li₂Se‐protected Li metal (denoted as LSSe@Li) exhibits a stable dendrite‐free cycling behavior over 900 h with a high lithium stripping/plating capacity of 3 mAh cm^?2 at 1.5 mA cm^?2 in the symmetrical cell. Compared to bare Li anode, full batteries paired with LiFePO₄, sulfur/carbon, and LiNi_0.6Co_0.2Mn_0.2O₂ cathodes all present better battery cycling and rate performance when LSSe@Li anode is used. Moreover, Li₂Se exhibits a lower lithium‐ion migration energy barrier in comparison with Li₂S which is proved by density functional theory calculation.     

A Surface Chemistry Approach to Tailoring the Hydrophilicity and Lithiophilicity of Carbon Films for Hosting High‐Performance Lithium Metal Anodes

Porous carbon scaffolds can host lithium (Li) metal anodes to potentially enable stable Li metal batteries. However, the poor Li metal wettability on the carbon surface has inhibited the uniform distribution of metallic Li on most carbon scaffolds. Herein, this work reports a lithiophilic top layer through mild surface ozonolysis and ammoniation methods can universally facilitate the infiltration of liquid Li metal into most carbon matrices. Based on this finding, thin, a lightweight Li@carbon film (CF) composite anode with a high practical capacity of 3222 mAh g^?1 and suppressed volume expansion and dendrite formation is reported. It is observed that the deep stripping/plating pre‐cycling yields dense, trunky Li metal in the Li@CF composite, which allows for favorable long‐term cycling performance. The full cell combining the thin Li@CF composite anode and a high‐mass‐loading, cobalt‐free cathode can deliver high reversible capacity, good cycle stability, and good rate capability in the conventional carbonate electrolyte. The present study further establishes the relationship between lithiophilicity and hydrophilicity for carbon materials as well as provides insights into improving the liquid Li metal infiltration into other carbon scaffolds.     

A Series of Hybrid Multifunctional Interfaces as Artificial SEI Layer for Realizing Dendrite Free,and Long-Life Sodium Metal Anodes (Adv. Funct. Mater. 42/2023)

Sodium metal (Na) anodes are considered the most promising anode for high-energy-density sodium batteries because of their high capacity and low electrochemical potential. However, Na metal anode undergoes uncontrolled Na dendrite growth, and unstable solid electrolyte interphase layer (SEI) formation during cycling, leading to poor coulombic efficiency, and shorter lifespan. Herein, a series of Na-ion conductive alloy-type protective interface (Na-In, Na-Bi, Na-Zn, Na-Sn) is studied as an artificial SEI layer to address the issues. The hybrid Na-ion conducting SEI components over the Na-alloy can facilitate uniform Na deposition by regulating Na-ion flux with low overpotential. Furthermore, density functional study reveals that the lower surface energy of protective alloys relative to bare Na is the key factor for facilitating facile ion diffusion across the interface. Na metal with interface layer facilitates a highly reversible Na plating/stripping for ≈790 h, higher than pristine Na metal (100 h). The hybrid self-regulating protective layers exhibit a high mechanical flexibility to promote dendrite free Na plating even at high current density (5 mA cm⁻²), high capacity (10 mAh cm⁻²), and good performance with Na₃V₂(PO₄)₃ cathode. The current study opens a new insight for designing dendrite Na metal anode for next generation energy storage devices.     

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.     

Dendrite‐Free Lithium Plating Induced by In Situ Transferring Protection Layer from Separator

Lithium (Li) metal anodes are regarded as a promising pathway to meet the rapidly growing requirements on high energy density cells, owing to their highest gravimetric capacity (3840 mAh g^?1) and their lowest redox potential. The application of Li metal anodes, however, is still hindered by undesired dendrites formation and endless consumption of liquid electrolyte due to a continuous reaction on interface of electrolyte/Li‐metal without a stable solid–electrolyte–interface (SEI) layer. A stable protection layer is formed on Li metal anode by in situ transferring the coating layer from polymer separator. The Li anode protection strategy is developed with an in situ formed protection layer transferred through the reduction of a coating layer on polymer separator. A PbZr_0.52Ti_0.48O₃ (PZT) coating layer on polypropylene (PP) separator is reduced by Li metal anode to produce a Pb metal containing composite layer, which could form Pb–Li alloy and adhere to the surface of Li metal anode after the reaction and improves the Li plating/stripping efficiency owing to the formation of a more homogenized electric field. Both the Li/Li symmetric cells and LiFePO₄/Li cells with this PZT precoated PP separators exhibit significantly improved Coulombic efficiency and cycling life.     

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.     

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.     

Amino Acid-Induced Interface Charge Engineering Enables Highly Reversible Zn Anode

Despite the impressive merits of low-cost and high-safety electrochemical energy storage for aqueous zinc ion batteries, researchers have long struggled against the unresolved issues of dendrite growth and the side reactions of zinc metal anodes. Herein, a new strategy of zinc-electrolyte interface charge engineering induced by amino acid additives is demonstrated for highly reversible zinc plating/stripping. Through electrostatic preferential absorption of positively charged arginine molecules on the surface of the zinc metal anode, a self-adaptive zinc-electrolyte interface is established for the inhibition of water adsorption/hydrogen evolution and the guidance of uniform zinc deposition. Consequently, an ultra-long stable cycling up to 2200 h at a high current density of 5 mA cm⁻² is achieved under an areal capacity of 4 mAh cm⁻². Even cycled at an ultra-high current density of 10 mA cm⁻², 900 h-long stable cycling is still demonstrated, demonstrating the reliable self-adaptive feature of the zinc-electrolyte interface. This work provides a new perspective of interface charge engineering in realizing highly reversible bulk zinc anode that can prompt its practical application in aqueous rechargeable zinc batteries.     

Solvent-Free Electrolyte for High-Temperature Rechargeable Lithium Metal Batteries

The formation of lithiophobic inorganic solid electrolyte interphase (SEI) on Li anode and cathode electrolyte interphase (CEI) on the cathode is beneficial for high-voltage Li metal batteries. However, in most liquid electrolytes, the decomposition of organic solvents inevitably forms organic components in the SEI and CEI. In addition, organic solvents often pose substantial safety risks due to their high volatility and flammability. Herein, an organic-solvent-free eutectic electrolyte based on low-melting alkali perfluorinated-sulfonimide salts is reported. The exclusive anion reduction on Li anode surface results in an inorganic, LiF-rich SEI with high capability to suppress Li dendrite, as evidenced by the high Li plating/stripping CE of 99.4% at 0.5  mA cm⁻² and 1.0 mAh cm⁻², and 200-cycle lifespan of full LiNi_0.8Co_0.15Al_0.05O₂ (2.0 mAh cm⁻²) || Li (20 µm) cells at 80 °C. The proposed eutectic electrolyte is promising for ultrasafe and high-energy Li metal batteries.     

A Novel 3D Li/Li9Al4/Li-Mg Alloy Anode for Superior Lithium Metal Batteries

Lithium metal has been recognized as the most promising anode material due to its high capacity and low electrode potential. However, the high reactivity, infinite volume variation, and uncontrolled dendrites growth of Li during long-term cycling severely limit its practical applications. To address these issues, herein, a novel 3D Al/Mg/Li alloy (denoted as AM-Li) anode is designed and constructed by a facile smelting-rolling strategy, which improves the surface stability, electrochemical cycling stability, and rate capability in lithium metal batteries. Specifically, the optimized AM-Li|AM-Li symmetric cell exhibits low polarization voltage (< 20 mV) and perfect cycling stability at 1 mA cm⁻²-1 mAh cm⁻² for more than 1600 h. Moreover, the AM-Li|NCM811 full cell exhibits superior rate capability up to 5 C and excellent cyclability for 100 cycles at 0.5 C with a high capacity retention of 90.8%. The realization of lithium-poor or lithium-free anode materials will be a major development trend of anode materials in the future. Therefore, the research shows that the construction of 3D alloy framework is beneficial to improve the cycling stability of Li anodes by suppressing the volume expansion effect and Li dendrite growth, which will promote the further development of lithium-poor metal anodes.     

Polysiloxane Cross-Linked Mechanically Stable MXene-Based Lithium Host for Ultrastable Lithium Metal Anodes with Ultrahigh Current Densities and Capacities

The applications of lithium metal anode are limited by uncontrollable lithium dendrite growth and infinite volume changes during cycling. These fundamental issues are exacerbated at high cycling current densities and capacities. Herein, a mechanically stable and resilient lithium metal host is fabricated by covalently cross-linking a highly-conductive and lithiophilic MXene/silver nanowire scaffold through a silylation reaction between MXene nanosheets and polysiloxane. Compared with the control sample (an MXene scaffold assembled by weak van der Waals forces), the covalently cross-linked MXene scaffold displays excellent mechanical strength and resilience, which is conducive to buffer the large internal stress fluctuations generated during rapid and deep lithium plating-stripping and guaranteed that the integrated framework structure is maintained during long-term charging-discharging cycles. When used in a symmetric cell, the lithium composite anode based on the covalently cross-linked MXene host affords an unprecedented cyclic lithium plating-stripping stability of a record-high 3000 h lifespan at an ultrahigh current density (20 mA cm⁻²) and areal capacity (10 mAh cm⁻²). When this composite anode is coupled with a LiNi_0.5Co_0.2Mn_0.3O₂ cathode, the full cell delivers an ultrahigh rate of 10 C for up to 1000 cycles, with an average capacity decay of 0.043% per cycle and a stable Coulombic efficiency of 98.7%.     

Fast-Charging and Ultrahigh-Capacity Zinc Metal Anode for High-Performance Aqueous Zinc-Ion Batteries

Although some strategies have been triggered to address the intrinsic drawbacks of zinc (Zn) anodes in aqueous Zn-ion batteries (ZIBs), the larger issue of Zn anodes unable to cycle at a high current density with large areal capacity is neglected. Herein, the zinc phosphorus solid solution alloy (ZnP) coated on Zn foil (Zn@ZnP) prepared via a high-efficiency electrodeposition method as a novel strategy is proposed. The phosphorus (P) atoms in the coating layer are beneficial to fast ion transfer and reducing the electrochemical activation energy during Zn stripping/plating processes. Besides, a lower energy barrier of Zn²⁺ transferring into the coating can be attained due to the additional P. The results show that the as-prepared Zn@ZnP anode in the symmetric cell can be cycled at a current density of 15 mA cm⁻² with an areal capacity of 48 mAh cm⁻² (depth of discharge, DOD ≈ 82%) and even at an ultrahigh current density of 20 mA cm⁻² and DOD ≈ 51%. Importantly, a discharge capacity of 154.4 mAh g⁻¹ in the Zn/MnO₂ full cell can be attained after 1000 cycles at 1 A g⁻¹. The remarkable effect achieved by the developed strategy confirms its prospect in the large-scale application of ZIBs for high-power devices.     

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.