Template-Sacrificed Hot Fusion Construction and Nanoseed Modification of 3D Porous Copper Nanoscaffold Host for Stable-Cycling Lithium Metal Anodes

Lithium (Li) metal anodes have been proposed as a promising candidate for high-energy-density electrode materials in secondary batteries. However, the dendrite growth and unstable electrode–electrolyte interfaces during Li plating/stripping are fatal to their practical applications. Herein, the construction of 3D porous Au/Cu nanoscaffold prepared via a convenient template-sacrificed hot fusion construction method and a nanoseed modification process as an effective Li metal hosting material are proposed. The Au/Cu nanoscaffold can spatially guide uniform deposition of Li metal free from the growth of Li dendrites due to the homogenous Li⁺ ion flux and negligible nucleation overpotential. Moreover, the Cu skeleton can relieve volume change and stabilize local current density during cycling processes. Benefiting from these advantages, the symmetric cells based on self-supported Li-filled Au/Cu (Li-Au/Cu) nanoscaffold electrodes present highly stable Li plating/stripping for more than 1000 h with a low voltage hysteresis less than 90 mV and a long lifespan over 1300 h at 1.0 mA cm^–2 in carbonate-based electrolytes. Impressively, the Li-Au/Cu nanoscaffold||LiFePO₄ full cells also exhibit exceptional cycling stability and rate performance. This work provides a promising strategy to construct dendrite-free lithium metal anodes toward high-performance lithium metal batteries.     

Strategies in Structure and Electrolyte Design for High-Performance Lithium Metal Batteries

Lithium metal is the “holy grail” anode for next-generation high-energy rechargeable batteries due to its high capacity and lowest redox potential among all reported anodes. However, the practical application of lithium metal batteries (LMBs) is hindered by safety concerns arising from uncontrollable Li dendrite growth and infinite volume change during the lithium plating and stripping process. The formation of stable solid electrolyte interphase (SEI) and the construction of robust 3D porous current collectors are effective approaches to overcoming the challenges of Li metal anode and promoting the practical application of LMBs. In this review, four strategies in structure and electrolyte design for high-performance Li metal anode, including surface coating, porous current collector, liquid electrolyte, and solid-state electrolyte are summarized. The challenges, opportunities, perspectives on future directions, and outlook for practical applications of Li metal anode, are also discussed.     

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.     

Anode‐Free Rechargeable Lithium Metal Batteries

Anode‐free rechargeable lithium (Li) batteries (AFLBs) are phenomenal energy storage systems due to their significantly increased energy density and reduced cost relative to Li‐ion batteries, as well as ease of assembly because of the absence of an active (reactive) anode material. However, significant challenges, including Li dendrite growth and low cycling Coulombic efficiency (CE), have prevented their practical implementation. Here, an anode‐free rechargeable lithium battery based on a Cu||LiFePO₄ cell structure with an extremely high CE (>99.8%) is reported for the first time. This results from the utilization of both an exceptionally stable electrolyte and optimized charge/discharge protocols, which minimize the corrosion of the in situly formed Li metal anode.     

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.     

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.     

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.     

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.     

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.     

Regulating Lithium Nucleation and Deposition via MOF‐Derived Co@C‐Modified Carbon Cloth for Stable Li Metal Anode

Lithium metal is an exciting anode candidate with extra high theoretical specific capacity for new high‐energy rechargeable batteries. However, uncontrolled Li deposition and an unsteady solid electrolyte interface seriously obstruct the commercial application of Li anodes in Li metal batteries. Herein, 3D carbon cloth (CC) supporting N‐doped carbon (CN) nanosheet arrays embedded with tiny Co nanoparticles (CC@CN‐Co) are employed as a lithiophilic framework to regulate homogenous Li nucleation/growth behavior in a working Li metal anode. The emergence of Li dendrites is supposed to be inhibited by the conductive 3D scaffold that reduces local current density. The uniform nucleation of Li can be guided by N‐containing functional groups as they have a strong interaction with Li atoms, and the tiny Co nanoparticles can provide active sites to guide Li deposition. As a result, the current CC@CN‐Co host exhibits Li dendrite–free features and stable cycling performance with a low overpotential (20 mV) throughout 800 h cycles. When paired with the typical LiFePO₄ (LFP) cathode, the assembled CC@CN‐Co@Li//LFP@C full cell exhibits outstanding rate capability and improved cycling performance.     

Homogeneous Li+ Flux Distribution Enables Highly Stable and Temperature-Tolerant Lithium Anode

3D carbon hosts can enable low-stress Li metal anodes (LMAs) with improved structural and interfacial stability. However, the uneven Li⁺ flux and large concentration polarization, resulting from intrinsically poor Li affinity and limited porosity of carbon scaffolds, make the precise control of Li plating/stripping still one the key challenges facing advanced LMAs. Here it is demonstrated that a lightweight carbon scaffold, featuring parallel-aligned porous fibers, can work well for homogeneous Li⁺ flux distribution and reduced concentration gradient to form a stable solid electrolyte interphase, and then synergistically guide smooth Li nucleation/growth even at low temperatures. As a result, the obtained LMAs delivers a high areal capacity up to 15 mAh cm⁻², ultralong lifespan (4800 cycles at 4 mA cm⁻²) with very low voltage hysteresis of ≈21 mV, a high practically available specific capacity of 863.9 mAh g⁻¹ after 1000 cycles, and a long-term stable behavior at low-temperature operation. As coupling with the commercial LiNi_1/3Co_1/3Mn_1/3O₂ cathodes and common carbonate-based electrolyte, the corresponding practical cells also possess an ultralong lifespan and outstanding low-temperature functionality. This study not only presents an advanced carbon host candidate but also sheds new light on crucial design principles of carbon scaffolds for practically feasible rechargeable metal batteries.     

Inorganic Filler Enhanced Formation of Stable Inorganic-Rich Solid Electrolyte Interphase for High Performance Lithium Metal Batteries

Lithium metal (LM) is a promising anode material for next generation lithium ion based electrochemical energy storage devices. Critical issues of unstable solid electrolyte interphases (SEIs) and dendrite growth however still impede its practical applications. Herein, a composite gel polymer electrolyte (GPE), formed through in situ polymerization of pentaerythritol tetraacrylate with fumed silica fillers, is developed to achieve high performance lithium metal batteries (LMBs). As evidenced theoretically and experimentally, the presence of SiO₂ not only accelerates Li⁺ transport but also regulates Li⁺ solvation sheath structures, thus facilitating fast kinetics and formation of stable LiF-rich interphase and achieving uniform Li depositions to suppress Li dendrite growth. The composite GPE-based Li||Cu half-cells and Li||Li symmetrical cells display high Coulombic efficiency (CE) of 90.3% after 450 cycles and maintain stability over 960 h at 3 mA cm⁻² and 3 mAh cm⁻², respectively. In addition, Li||LiFePO₄ full-cells with a LM anode of limited Li supply of 4 mAh cm⁻² achieve capacity retention of 68.5% after 700 cycles at 0.5 C (1 C = 170 mA g⁻¹). Especially, when further applied in anode-free LMBs, the carbon cloth||LiFePO₄ full-cell exhibits excellent cycling stability with an average CE of 99.94% and capacity retention of 90.3% at the 160th cycle at 0.5 C.     

Ultrafine Titanium Nitride Sheath Decorated Carbon Nanofiber Network Enabling Stable Lithium Metal Anodes

Nonuniform local electric field and few nucleation sites on the reactive interface tend to cause detrimental lithium (Li) dendrites, which incur severe safety hazards and hamper the practical application of Li metal anodes in batteries. Herein, a carbon nanofiber (CNF) mat decorated with ultrafine titanium nitride (TiN) nanoparticles (CNF‐TiN) as both current collector and host material is reported for Li metal anodes. Uniform Li deposition is achieved by a synergetic effect of lithiophilic TiN and 3D CNF configuration with a highly conductive network. Theoretical calculations reveal that Li prefers to be adsorbed onto the TiN sheath with a low diffusion energy barrier, leading to controllable nucleation sites and dendrite‐free Li deposits. Moreover, the pseudocapacitive behavior of TiN identified through kinetics analysis is favorable for ultrafast Li⁺ storage and the charge transfer process, especially under a high plating/stripping rate. The CNF‐TiN‐modified Li anodes deliver lower nucleation overpotential for Li plating and superior electrochemical performance under a large current density (200 cycles at 3 mA cm^?2) and high capacity (100 cycles with 6 mAh cm^?2), as well as a long‐running lifespan (>600 h). The CNF‐TiN‐based full cells using lithium iron phosphate and sulfur cathodes exhibit excellent cycling stability.     

Hierarchical Co3O4 Nanofiber–Carbon Sheet Skeleton with Superior Na/Li‐Philic Property Enabling Highly Stable Alkali Metal Batteries

Uncontrollable dendritic behavior and infinite volume expansion in alkali metal anode results in the severe safety hazards and short lifespan for high‐energy batteries. Constructing a stable host with superior Na/Li‐philic properties is a prerequisite for commercialization. Here, it is demonstrated that the small Gibbs free energy change in the reaction between metal oxide (Co₃O₄, SnO₂, and CuO) and alkali metal is key for metal infusion. The as‐prepared hierarchical Co₃O₄ nanofiber–carbon sheet (CS) skeleton shows improved wettability toward molten Li/Na. The 3D carbon sheet serves as a primary framework, offering adequate lithium nucleation sites and sufficient electrolyte/electrode contact for fast charge transfer. The secondary framework of Co/Li₂O nanofibers provides physical confinement of deposited Li and further redistributes the Li⁺ flux on each carbon fiber, which is verified by COMSOL Multiphysics simulations. Due to the uniform deposition behavior and near‐zero volume change, modified symmetrical Li/Li cells can operate under an ultrahigh current density of 20 mA cm^?2 for more than 120 cycles. When paired with LiFePO₄ cathodes, the Li/Co–CS cell shows low polarization and 88.4% capacity retention after 200 cycles under 2 C. Convincing improvement can also be observed in Na/Co–CS symmetrical cells applying NaClO₄‐based electrolyte. These results illustrate a significant improvement in developing safe and stable alkali metal batteries.     

In Situ Construction of Lithium Silicide Host with Unhindered Lithium Spread for Dendrite-Free Lithium Metal Anode

Performance degradation and safety issue caused by Li dendrite growth and huge volume variation hinder the practical application of Li metal anode in high-energy-density lithium batteries. Li diffusion barrier of the host is a key parameter that determines the dendrite growth. Herein, a stable Li₂₁Si₅ alloy host with very low Li diffusion barriers is designed and prepared by an in situ metallurgical method using low-cost micron silicon precursor. The low diffusion barrier of Li₂₁Si₅ host enables a dendrite-free Li deposition behavior. It is revealed that the in-situ formed porous Li₂₁Si₅ host not only has high Li affinity, but also suppresses volume variation of the electrode effectively and thus keeps superior structural stability during Li stripping and plating processes. As a result, this new Li metal anode with Li₂₁Si₅ host exhibits promising cycle stability and rate capability with low polarization in both symmetric and full cells. This study opens new opportunities for using alloy-based materials as the hosts for Li composite anodes.     

A Facile Way to Construct Stable and Ionic Conductive Lithium Sulfide Nanoparticles Composed Solid Electrolyte Interphase on Li Metal Anode

Due to the high theoretical capacity and low reduction potential, metallic lithium is a promising anode material for the next generation of high-energy-density batteries. However, the dynamic Li plating/stripping process can easily destroy the unstable solid electrolyte interphase (SEI) and cause dendrite growth. Here, an artificial lithium sulfide nanoparticle composed SEI layer with superior stability and high ionic conductivity is designed by a spray quenching method. The artificial SEI layer on Li surface can effectively minimize the side reactions and suppress Li dendrite growth, and the metal electrode delivers stable cycling for 500 cycles in the symmetrical cell with carbonate electrolyte. Moreover, when this SEI-modified Li anode is coupled with a LiFePO₄ cathode, the full cell shows promoted cycling stability and rate capability. This work provides a broadly applicable and facile strategy to address the intrinsic issues of lithium metal anodes.     

Low-Cost Regulating Lithium Deposition Behaviors by Transition Metal Oxide Coating on Separator

The application of lithium metal anode, despite being of the highest capacity, is hindered by low Coulombic efficiency (CE) and serious lithium dendrites formation. A strategy of transition metal oxides (TMOs) particles coated porous polypropylene (PP) separator is developed to regulate lithium deposition behaviors through in situ forming artificial solid electrolyte interface (SEI) passivating layers. By virtue of quite low solubilities of TMOs in the electrolyte, the concentration of TMOs in the electrolyte can be maintained at a constant and the dissolved TMOs can be reduced to produce Li₂O and Mn particles, which not only function as lithium nucleating seeds but are also involved in the formation of the SEI layer. The sustainably existed trace of TMOs ensures the artificial SEI layer can be re-healed once damaged by the volume expansion of lithium. With the help of one typical TMO of MnO coating on PP, an interesting dendrite-free dual layer Li deposition is observed, which significantly improves the CE of Li||Cu cells and cycling life of Li||Li cells. Using MnO coated PP, ultra-thin lithium films are deposited on copper foils with an in situ constructed SEI passivating layer, which exhibits a much improved cycling performance in liquid ether electrolyte and even better performance in gel polymer electrolyte.     

Unlocking the Potential of Lithium Metal Batteries With a Sulfite-Based Electrolyte

Lithium metal batteries (LMBs) have the potential to significantly increase the energy density of advanced batteries in the future. Nonetheless, the dendritic lithium structures and low Coulombic efficiency (CE) of LMBs currently impede their applied implementation. Herein, a sulfite-based electrolyte (SBE/FEC), including 1.0 m lithium bis(fluorosulfonyl)imide in a blend of ethylene sulfite and diethyl sulfite, and 5 wt% fluoroethylene carbonate is proposed. SBE/FEC is a highly efficient inhibitor against the growth of lithium dendrites through the formation of robust solid electrolyte interphase (SEI) layer. Raman spectroscopy and theoretical calculation indicate that in SBE/FEC, a significant portion of FSI⁻ exists in associated complexes, playing a vital role in the creation of LiF-rich passivation. Besides, the sulfite solvents decompose and yield polysulfide complexes in the SEI layer. A direct correlation between the proportion of cation–anion complexes and the contact angle between electrolyte and separator is elucidated through molecular dynamics simulations. The SBE/FEC system exhibits high CEs (98.3%) with Li||Cu cells, along with a steady discharge capacity of ≈137 mA h g⁻¹ in Li||LiFePO₄ cell. This study presents an effective approach for enhancing LMBs with sulfite-based electrolytes, which can lead to high-energy-density next-generation rechargeable batteries.     

Artificial Graphite Paper as a Corrosion-Resistant Current Collector for Long-Life Lithium Metal Batteries

The employment of ultra-thin lithium metal anode with high loading cathode is the key to realizing high-energy-density rechargeable lithium batteries. Ultra-thin lithium foils are routinely loaded on a copper substrate in batteries, however, the close contact of these two metals causes galvanic corrosion in the presence of electrolyte, which results in irreversible consumption of lithium and decomposition of electrolyte. Herein, a lightweight and highly conductive flexible graphite paper (GP) is applied to replace Cu foil as the current collector for lithium metal anode. It is demonstrated that the application of GP prevents galvanic corrosion and maintains intimate and steady contact between Li foil and GP current collector during cycling, thereby improving the electrochemical performance of the battery. A 1.08 Ah pouch cell assembled with Li@GP anode and LiNi_0.8Co_0.1Mn_0.1O₂ cathode exhibits a long lifetime of 240 cycles with a capacity retention of 91.6% under limited Li, high cathode loading and lean electrolyte conditions.     

Sol Electrolyte: Pathway to Long-Term Stable Lithium Metal Anode

Lithium (Li) metal batteries are the subject of intense study due to their high energy densities. However, uncontrolled dendrite growth and the resulting pulverization of Li foil during the repeated plating/stripping process seriously diminish their cycling life. Herein, a facile approach using octaphenyl polyoxyethylene (OP-10)-based sol electrolyte is proposed to alleviate Li anode pulverization. This sol electrolyte possesses better ionic conductivity compared to gel and solid-state electrolytes and also homogenizes Li ion diffusion throughout the entire electrolyte efficiently. As a result, Li/Li symmetric cells using this sol electrolyte demonstrate long-term cycling stability for up to 1800 h, with a plating capacity of 3.0 mAh cm⁻² without deteriorating the integrity of the thin Li foil. Using a conventional liquid electrolyte, electrode pulverization and battery failure can be observed after just three cycles. More importantly, a parameter of “throwing power” is introduced in a metal Li battery system to characterize the homogenizing ability of Li deposition in different electrolyte systems, which can serve as a guide to the efficient selection of electrolytes for Li metal batteries.