A chemical lithiation induced Li4.4Sn lithiophilic layer for anode-free lithium metal batteries

Abstract

Among the battery systems involving a lithium containing cathode, the anode-free lithium metal battery (AFLMB) exhibits the highest potential energy density. However, the lack of excess lithium amplifies the problems of dendritic Li growth, dead lithium formation, parasitic reactions, etc. The surface properties of the current collector play a crucial role in affecting the cycling stability of AFLMBs. Herein, we use a simple chemical pre-lithiation method to form a thin Li_4.4Sn coating layer with a fully lithiated phase on Cu foil (Li_4.4Sn@Cu). The lithiophilic Li_4.4Sn layer is conducive to fast electrochemical kinetics and induces higher nucleation density, which facilitates the epitaxial and dense deposition of Li ions. The dense Li deposition reduces the consumption of active lithium due to the inhibited side reactions between lithium and the electrolyte. Thus, anode-free lithium metal pouch cells assembled with Li_4.4Sn@Cu and a LiNi_0.8Co_0.1Mn_0.1O₂ cathode with an areal capacity of 4 mA h cm⁻² exhibits a high capacity retention of 85.5% after 50 cycles with an energy density of 355 W h kg⁻¹ under limited electrolyte addition of 2 g A h⁻¹.