Stable deposition/stripping of lithium metal for long lifespan batteries by shielding electrical double layer interference with a lithiated TiO2 cap

Li-metal batteries face challenges including low cyclability and fire risk due to dendrite growth from uneven charge distribution at the solid-liquid interface, exacerbated by surface roughness. In this study, a lithiated TiO2 cap was incorporated onto a Li-metal anode in a full cell configuration. The film, deposited on a PP separator by magnetron sputtering, provided excellent ionic conductivity and anti-static properties. The interface between the Li-ion deposition and electrical double layer was effectively isolated, preventing short circuits. This arrangement eliminates the corona effect resulting from electron accumulation on the Li metal electrode. Under the protective influence of the cap, Li-ion deposition and stripping occur on the anodes without dendrite growth, leading to exceptional cyclability in the newly designed cell. Symmetrical cells containing the modified separator exhibit stable cycling for 2000 h at both 1 mA cm-2 and 5 mA cm- 2, with an areal capacity of 1 mA h cm- 2. Furthermore, when combined with a commercial cathode material of LiFePO4, the cell demonstrates impressive cycle stability, withstanding 600 cycles at a current density of 1 C. This innovative approach holds promise for enhancing the performance and safety of lithium-metal batteries in practical applications.