An ultrathin Li-doped perovskite SEI film with high Li ion flux for a fast charging lithium metal battery†

Abstract

Developing an artificial solid electrolyte interphase (SEI) with high Li ion flux is vital to improve the cycling stability of lithium metal batteries, especially under a high rate. In this work, a novel artificial SEI film was prepared via in situ deposition of a lithium-doped cesium lead chloride perovskite (Li–CsPbCl₃). Benefiting from its ultra-high thickness (0.45 μm), high mechanical modulus (5.9 GPa), high lithium-ion migration number (0.57), and unique highly oriented framework, the Li–CsPbCl₃ SEI film could promote the rapid transport and uniform deposition of lithium ions, enhancing the stability of lithium deposition and stripping. As a result, Li/Li symmetric cells based on the Li–CsPbCl₃ protective film could cycle stably for 1300 hours under high current density of 10 mA cm⁻². In addition, the Li/LiFePO₄ battery using the Li–CsPbCl₃ SEI film showed an impressive cycling stability with a capacity retention rate of up to 91.4% after 230 cycles at a high current rate of 3C.