Magnetron sputtering deposition of titanium films on the surface of Li₆.₄La₃Zr₁.₄Ta₀.₆O₁₂ electrolyte tablets

The garnet-type Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 (LLZTO) is considered a promising solid-state electrolyte (SSE) due to its high ionic conductivity and electrochemical stability. However, the surface of LLZTO easily reacts with H 2 O and CO 2 in the air, forming a passivation layer of Li 2 CO 3 . This reaction further deteriorates the interface between LLZTO and the Li anode, resulting in poor wettability. Consequently, significant gaps form between LLZTO and the Li anode, leading to uneven deposition of Li during the cycling. Li dendrites can grow into these gaps, eventually penetrating the electrolyte and causing a short circuit in the battery. In this study, a surface modification method is investigated, where a thin film of titanium is deposited onto the surface of LLZTO electrolyte tablets using magnetron sputtering. The effects of magnetron sputtering deposition titanium film process parameters—chamber pressure, bias voltage, and temperature—on the electrochemical properties of button cells were investigated. The results indicated that LLZTO electrolyte tablets coated with titanium exhibited low interfacial resistance, high cycle stability, and significant inhibition of Li dendrites under optimized conditions of 1.0 Pa chamber pressure, 100 V bias voltage, and 150 ℃ temperature. Under these conditions, the interface resistance decreased significantly from 1437.9 Ω to 190.19 Ω. Additionally, the Li symmetric cell assembled with the titanium-coated LLZTO electrolyte tablet demonstrated stable cycling for over 1200 h at 25 ℃ under a current density of 0.1 mA·cm −2 .