Lithiophilic and Antioxidative Copper Current Collectors for Highly Stable Lithium Metal Batteries

Designing copper (Cu) current collectors is a convenient way to stabilize lithium (Li) metal anodes. However, Cu current collectors and their derived Li/Cu anodes still face several obstacles, including lithiophobic and oxidizable Cu surface, cumbersome anode fabrication process, and low Li utilization. Here, a formate-treatment strategy is presented to reconstruct Cu current collectors with a passivation layer covered Cu(110) surface. This method can easily be generalized to increase the lithiophilicity and oxidation resistibility of Cu current collectors. Using the formate-treated Cu nanowire network as an anode current collector, the full cell consisting of a LiFePO₄ cathode and Li/Cu anode with a low negative/positive capacity ratio delivers an excellent cycling performance with 74.8% capacity retention after 1000 cycles at 1 C. In addition, a concept of an upper current collector is introduced to simplify the manufacturing procedure of Li/Cu anodes. This work provides new insights into the design and construction of high-performance Li/Cu anodes.     

Super‐Aligned Carbon Nanotube Films as Current Collectors for Lightweight and Flexible Lithium Ion Batteries

Carbon nanotube (CNT) current collectors with excellent flexibility, extremely low density (0.04 mg cm^?2), and tunable thickness are fabricated by cross‐stacking continuous CNT films drawn from super‐aligned CNT arrays. Compared with metal current collectors, better wetting, stronger adhesion, greater mechanical durability, and lower contact resistance are demonstrated at the electrode/CNT interface. Electrodes with CNT current collectors show improvements in cycling stability, rate capability, and gravimetric energy density over those with metal current collectors. These results suggest that CNT films can function as a promising type of current collector for lightweight and flexible lithium ion batteries with high energy density.     

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.     

A Patterned 3D Silicon Anode Fabricated by Electrodeposition on a Virus‐Structured Current Collector

Electrochemical methods were developed for the deposition of nanosilicon onto a 3D virus‐structured nickel current collector. This nickel current collector is composed of self‐assembled nanowire‐like rods of genetically modified tobacco mosaic virus (TMV1cys), chemically coated in nickel to create a complex high surface area conductive substrate. The electrochemically depo­sited 3D silicon anodes demonstrate outstanding rate performance, cycling stability, and rate capability. Electrodeposition thus provides a unique means of fabricating silicon anode materials on complex substrates at low cost.     

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.     

Lithium-Ion Desolvation Induced by Nitrate Additives Reveals New Insights into High Performance Lithium Batteries

Electrolyte additives have been widely used to address critical issues in current metal (ion) battery technologies. While their functions as solid electrolyte interface forming agents are reasonably well-understood, their interactions in the liquid electrolyte environment remain rather elusive. This lack of knowledge represents a significant bottleneck that hinders the development of improved electrolyte systems. Here, the key role of additives in promoting cation (e.g., Li⁺) desolvation is unraveled. In particular, nitrate anions (NO₃⁻) are found to incorporate into the solvation shells, change the local environment of cations (e.g., Li⁺) as well as their coordination in the electrolytes. The combination of these effects leads to effective Li⁺ desolvation and enhanced battery performance. Remarkably, the inexpensive NaNO₃ can successfully substitute the widely used LiNO₃ offering superior long-term stability of Li⁺ (de-)intercalation at the graphite anode and suppressed polysulfide shuttle effect at the sulfur cathode, while enhancing the performance of lithium–sulfur full batteries (initial capacity of 1153 mAh g⁻¹ at 0.25C) with Coulombic efficiency of ≈100% over 300 cycles. This work provides important new insights into the unexplored effects of additives and paves the way to developing improved electrolytes for electrochemical energy storage applications.     

3D Carbonaceous Current Collectors: The Origin of Enhanced Cycling Stability for High‐Sulfur‐Loading Lithium–Sulfur Batteries

The cycling stability of high‐sulfur‐loading lithium–sulfur (Li–S) batteries remains a great challenge owing to the exaggerated shuttle problem and interface instability. Despite enormous efforts on design of advanced electrodes and electrolytes, the stability issue raised from current collectors has been rarely concerned. This study demonstrates that rationally designing a 3D carbonaceous macroporous current collector is an efficient and effective “two‐in‐one” strategy to improve the cycling stability of high‐sulfur‐loading Li–S batteries, which is highly versatile to enable various composite cathodes with sulfur loading >3.7 mAh cm^?2. The best cycling performance can be achieved upon 950 cycles with a very low decay rate of 0.029%. Moreover, the origin of such a huge enhancement in cycling stability is ascribed to (1) the inhibition of electrochemical corrosion, which severely occurs on the typical Al foil and disables its long‐term sustainability for charge transfer, and (2) the passivation of cathode surface. The role of the chemical resistivity against corrosion and favorable macroscopic porous structure is highlighted for exploiting novel current collectors toward exceptional cycling stability of high‐sulfur‐loading Li–S batteries.     

Suppressing Lithium Dendrite Growth by Metallic Coating on a Separator

Lithium (Li) metal is one of the most promising candidates for the anode in high‐energy‐density batteries. However, Li dendrite growth induces a significant safety concerns in these batteries. Here, a multifunctional separator through coating a thin electronic conductive film on one side of the conventional polymer separator facing the Li anode is proposed for the purpose of Li dendrite suppression and cycling stability improvement. The ultrathin Cu film on one side of the polyethylene support serves as an additional conducting agent to facilitate electrochemical stripping/deposition of Li metal with less accumulation of electrically isolated or “dead” Li. Furthermore, its electrically conductive nature guides the backside plating of Li metal and modulates the Li deposition morphology via dendrite merging. In addition, metallic Cu film coating can also improve thermal stability of the separator and enhance the safety of the batteries. Due to its unique beneficial features, this separator enables stable cycling of Li metal anode with enhanced Coulombic efficiency during extended cycles in Li metal batteries and increases the lifetime of Li metal anode by preventing short‐circuit failures even under extensive Li metal deposition.     

Artificial Soft–Rigid Protective Layer for Dendrite‐Free Lithium Metal Anode

Lithium (Li) metal has been pursued as “Holy Grail” among various anode materials due to its high specific capacity and the lowest reduction potential. However, uncontrolled growth of Li dendrites and extremely unstable interfaces during repeated Li plating/stripping ineluctably plague the practical applications of Li metal batteries. Herein, an artificial protective layer with synergistic soft–rigid feature is constructed on the Li metal anode to offer superior interfacial stability during long‐term cycles. By suppressing random Li deposition and the formation of isolated Li, such a protective layer enables a dendrite‐free morphology of Li metal anode and suppresses the depletion of Li metal and electrolyte. Additionally, sufficient ionic conductivity is guaranteed through the synergy between soft and rigid structural units that are uniformly dispersed in the layer. Dendrite‐free and dense Li deposition, as well as a greatly reduced interfacial resistance after cycling, is achieved owing to the stabilized interface, accounting for significantly prolonged cycle life of Li metal batteries. This work highlights the ability of synergistic organic/inorganic protective layer in stabilizing Li metal anode and provides fresh insights into the energy chemistry and mechanics of anode in a working battery.     

Design of a Multifunctional Interlayer for NASCION‐Based Solid‐State Li Metal Batteries

NASCION‐type Li conductors have great potential to bring high capacity solid‐state batteries to realization, related to its properties such as high ionic conductivity, stability under ambient conditions, wide electrochemical stability window, and inexpensive production. However, their chemical and thermal instability toward metallic lithium (Li) has severely hindered attempts to utilize Li as anode material in NASCION‐based battery systems. In this work, it is shown how a tailored multifunctional interlayer between the solid electrolyte and Li anode can successfully address the interfacial issues. This interlayer is designed by creating a quasi‐solid‐state paste in which the functionalities of LAGP (Li_1.5Al_0.5Ge_1.5(PO₄)₃) nanoparticles and an ionic liquid (IL) electrolyte are combined. In a solid‐sate cell, the LAGP‐IL interlayer separates the Li metal from bulk LAGP and creates a chemically stable interface with low resistance (≈5 Ω cm²) and efficiently prevents thermal runaway at elevated temperatures (300 °C). Solid‐state cells designed with the interlayer can be operated at high current densities, 1 mA cm^?2, and enable high rate capability with high safety. Here developed strategy provides a generic path to design interlayers for solid‐state Li 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.     

Dendrite Suppression by a Polymer Coating: A Coarse‐Grained Molecular Study

A major hurdle to the successful deployment of high‐energy‐density lithium metal based batteries is dendrite growth during battery cycling, which raises safety and cycle life concerns. Coating the Li metal anode with a soft polymer layer has been previously shown to be effective in suppressing dendrite growth, leading to uniform lithium deposition even at high current densities. A 3D coarse‐grained molecular model to study the mechanism of dendrite suppression is presented. It is found that the most effective coatings delay or even prevent dendrites from penetrating the polymer layer during deposition. The optimal deposition can be achieved by jointly tuning the polymer stiffness and relaxation time. Higher polymer dielectric permittivity and coating thickness are also effective, but the deposition rate and, therefore, the charging current density is reduced. These findings provide the basis for rational design of soft polymer coatings for stable lithium deposition.