Realizing Dendrite-Free Lithium Deposition with a Composite Separator.

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 in situ 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.