Realizing Dendrite-Free Lithium Deposition with a Composite Separator

Abstract

A dendrite-free Li deposition strategy is developed with a composite separator of MnCO₃ coated porous polypropylene. Mn²⁺ ions are preferentially reduced to form Mn nanoparticles on Li anodes, which helped to reduce the nucleation overpotential and achieve a dendrite-free deposition of Li bulky grains. When MnCO₃ contacts the Li metal anode directly, an <i>in situ</i> artificial solid electrolyte interphase passivating layer was created from the reaction of Li metal, MnCO₃ and liquid electrolyte. Li metal anodes show significantly improved stability for more than 2000 h of plating/stripping in Li||Li symmetric cells. The homemade ultrathin Li films on Cu foils (Li@Cu), obtained by electrochemical Li deposition with PP/MnCO₃ separators, give enhanced cycling stability in LFP||Li@Cu cells. Combined with gel polymer electrolyte, the cycling stability of quasi-solid-state LFP||Li@Cu was further improved. This strategy for dendrite-free deposition via a composite separator provides a low-cost but efficient choice for alkaline metal batteries.