The utilization of an anode-free lithium-metal battery (AFLMB) is pivotal in meeting the high-energy-density demand for portable electronic devices and vehicles. However, the dendritic growth of lithium (Li) and continuous SEI formation on Copper (Cu) current collector limits the lifetime of a cell. Here we report the effect of milled Al 2 O 3 /polyacrylonitrile (PAN) composite layer (AOP) coated on Cu, as AOP@Cu, to encourage compact and smoother Li + deposition extracted from NMC (333) cathode. The excellent wettable nature of the AOP layer promotes uniform ionic flux and improved kinetics. The multifunctional AOP layer offers moderate mechanical support and sufficient strength to the SEI layer to suppress dendritic growth. The formation of Li−Al−O/Al 2 O 3 species at the bottom part of the layer reveals AOP's lithiophilicity to form new SEI components, besides Al−F, by regulating Li + deposition. PAN synergism is manifested by its flexible binding role and nitrogen content that has an excellent affinity to Li + . The resulting AOP@Cu||NMC and AOP@Cu||Li cells demonstrated improved cycling stability and Coulombic efficiency. An AOP@Cu||NMC cell run at 0.2 mA cm −2 exhibits a first cycle discharge capacity of 160 mAh g −1 that retains 30% after 82 cycles, whereas the Cu||NMC cell retains ∼30% after only 52 cycles.

Anode-free lithium metal batteries (AFLMBs) have been extensively studied due to their intrinsic high energy and safety without a metallic Li anode in cell design. Yet, the dendrite and dead-Li buildup continuously consumes the active Li upon cycling, leading to the poor lifespan of AFLMBs. Here, we introduce lithium oxalate into the cathode as an electrode additive providing a Li reservoir to extend the lifespan of AFLMBs. The AFLMB using 20% lithium oxalate and a LiNi0.3Co0.3Mn0.3O2 composite cathode exhibits >80 and 40% capacity retention after 50 and 100 cycles, respectively, outperforming the poor cycle life of fewer than 20 cycles obtained from the cell using a pure LiNi0.3Co0.3Mn0.3O2 cathode. Surprisingly, the average Coulombic efficiency of AFLMBs is found to improve as the amount of lithium oxalate increases in the composite cathode. This abnormal phenomenon could be attributed to the as-formed carbon dioxide after the first activation cycle forming a Li2CO3-rich solid–electrolyte interphase and improving the Li deposition and stripping efficiency. The findings in this work provide a new strategy to delay the capacity roll-over of AFLMBs from an electrode engineering perspective, which can be coupled with other approaches such as functional electrolytes synergistically to further improve the cycle life of AFLMBs for practical application.