Revisiting the lithium metal anode fading mechanisms and protective design principles under practical operation conditions

The ever-expanding electric vehicle market requires high-energy batteries with enhanced safety, which has attracted increasing global research attention. The lithium metal battery is considered a promising candidate because of its high theoretical energy density. However, the unstable lithium metal anode interphase and severe lithium dendrite formation hinder the battery's electrochemical performance and create a huge safety hazard. Additionally, the constant anode side reactions result in continuous lithium and electrolyte consumption, further limiting the commercialization of lithium metal batteries under practical low lithium excess and lean electrolyte conditions. This review mainly focuses on the recent progress in protecting the lithium metal anode under practical operation conditions. The existing issues that lead to the instability of lithium metal anodes (e.g., dendritic deposition, unstable interphase, and cathode crossover) and their formation mechanism are discussed. Moreover, various strategies regarding constructing stable lithium metal anodes under practical operation conditions, including electrode design, interphase engineering, and crossover blocking, are introduced. In the end, the perspectives and challenges of developing stable lithium metal batteries are presented.