Polydopamine layer-coated porous Ni foam host for Li metal batteries under lean electrolytic cell operations

Abstract

Li metal batteries (LMBs) face challenges such as volume change, dendrite growth, electrolyte depletion, and safety concerns. To address these issues, employing three-dimensional (3D) porous substrates and artificial solid electrolyte interphase (SEI) layers has been proposed for uniform Li ion distribution and interfacial stability. Here, we present a dendrite-free Li metal anode for LMBs operating under lean electrolytic conditions. This is achieved by synergistically combining oxidized 3D Ni foam as a conductive substrate and polydopamine (PDA) coating as an artificial SEI layer. The oxidized 3D Ni foam provides abundant lithiophilic sites with a large surface area for Li-ion deposition, effectively mitigating volume expansion due to its high elastic modulus. The PDA artificial SEI layer acts as a protective barrier, enhancing electrolyte wettability and preventing direct contact with Li metal surface. The PDA-coated oxidized 3D Ni foam demonstrates stabilized operation in full cell even with a small amount of electrolyte, achieving a Coulombic efficiency of approximately 99 % over 150 cycles and an exceptionally low voltage hysteresis (∼10 mV) for over 400 h. Our approach utilizing the highly conductive 3D foam substrate and the passivating PDA SEI layer enables outstanding electrochemical performance, opening avenues for future research on commercially viable LMBs.