Electrochemical Polishing: An Effective Strategy for Eliminating Li Dendrites

Dendritic growth of lithium (Li) is well-known to originate from deposition on rough and inhomogeneous Li-metal surfaces, and has long been a central problem in charging lithium metal batteries. Herein, a universal strategy is proposed for dendrite suppression by both in situ and ex situ electrochemical polishing of Li metal from the corrosion science perspective. This polishing technique greatly smoothens the surface of the Li and dynamically regenerates a homogeneous solid electrolyte interphase film simultaneously during cell cycling, which suppresses the nucleation sites for dendritic Li and establishes an ideal matrix for even deposition of Li. As a result, the polished Li presents a stable voltage profile and high Li utilization in both the symmetric cells and the full cells coupled with LiNi0.8Co0.1Mn0.1O2 (NCM811) or LiFePO4. The long cycle life of polished Li electrodes clearly demonstrates a uniform dendrite-free deposition of Li. This strategy shows a new direction to realize a uniform deposition of Li by providing a regenerative homogeneous Li-surface during repeated cycling.