In Situ Reaction Fabrication of a Mixed-Ion/Electron-Conducting Skeleton Toward Stable Lithium Metal Anodes

Abstract

Lithium metal batteries are emerging as a strong candidate in the future energy storage market due to its extremely high energy density. However, the uncontrollable lithium dendrites and volume change of lithium metal anodes severely hinder its application. In this work, the porous Cu skeleton modified with Cu₆Sn₅ layer is prepared via dealloying brass foil following a facile electroless process. The porous Cu skeleton with large specific surface area and high electronic conductivity effectively reduces the local current density. The Cu₆Sn₅ can react with lithium during the discharge process to form lithiophilic Li₇Sn₂ in situ to promote Li-ions transport and reduce the nucleation energy barrier of lithium to guide the uniform lithium deposition. Therefore, more than 300 cycles at 1 mA cm⁻² are achieved in the half-cell with an average Coulombic efficiency of 97.5%. The symmetric cell shows a superior cycle life of more than 1000 h at 1 mA cm⁻² with a small average hysteresis voltage of 16 mV. When coupled with LiFePO₄ cathode, the full cell also maintains excellent cycling and rate performance.