Reconstruction of\nLiF-Rich Interfaces through a Lithium\nFormate Additive for Anode-Free Lithium Metal Batteries

Abstract

Anode-free lithium metal batteries (AFLMBs) offer high\nenergy density\nand enhanced safety due to no excess lithium (Li) in the anode. Nevertheless,\nLi dendrite growth and dead Li formation rapidly consume the limited\nactive Li in AFLMBs, resulting in a low Coulombic efficiency (CE)\nand accelerated battery capacity deterioration. Herein, a Li reservoir\nis established by incorporating lithium formate (CHLiO₂) into both the cathode and anode as a Li salt additive for interface\nreconstruction, which improves the cycling stability of AFLMBs. Density\nfunctional theory calculation confirms that CHLiO₂ exhibits\nrelatively lower lowest unoccupied molecule orbital (LUMO) energies\nand higher highest occupied molecular orbital (HOMO) energies compared\nto the carbonate electrolyte solvents. The integration of CHLiO₂ significantly promotes the reconstruction of LiF-rich interfaces\nand effectively prevents continuous electrolyte decomposition, which\ncontributes to uniform Li deposition and suppresses active Li consumption.\nAfter the introduction of the CHLiO₂ additive, the Cu||NCM811\ncell retains an average CE of 97.3% during 40 cycles. This study provides\na simple yet effective methodology to supply an extra Li source and\nreconstruct LiF-rich interfaces for extending the cycling life of\nAFLMBs.