Stable ultrathin lithium metal anode enabled by self-adapting electrochemical regulating strategy

Ultrathin lithium metal foils with controllable capacity could realize high-specific-energy batteries, however, the pulverization of Li metal foils due to its extreme volume change results in rapid active Li loss and capacity fading. Here, we report a strategy to stabilize ultrathin Li metal anode via in-situ transferring Li from ultrathin Li foil into a well-designed 3D gradient host during cycling process. A 3D carbon fiber with gradient distribution of Ag nanoparticles is placed on the ultrathin Li foil in advance and acts as a Li reservoir, guiding Li deposition into its interior and thus alleviating the volume change of ultrathin Li foil anode. Hence, a high reversibility of Li metal is achieved and Li pulverization is suppressed, which can be witnessed by a long cyclic life in the symmetric cells. The proposed method offers a versatile and facile approach for protecting ultrathin Li metal anode, which will boost their commercial application process.