Anti-Perovskite Interphase Engineering Enables Dendrite-free Garnet Solid-State Electrolytes

Garnet-type Li7La3Zr2O12 (LLZO) is widely regarded as one of the most promising solid-state electrolytes due to its high ionic conductivity and chemical stability. However, the in-compact structure with voids between LLZO particles causes high resistance, significantly limiting the electrochemical performance of solid-state lithium-ion batteries. Herein, we present a wet chemical method combined with vacuum sintering for melt-injecting the low melting point anti-perovskite Li2OHCl that forms in situ at the grain boundaries of LLZO via capillary. A three-dimensional Li+ conduction pathway through the LLZO bulk is built to lower the interface resistance between the electrolyte and Li metal to 15.2 Ω cm–2, achieving a high total ionic conductivity of 6.2 × 10–4 S cm–1 at room temperature. The electron-blocking properties efficiently reduce the lithium dendrite growth during lithium plating-stripping, enabling stable cycling of Li symmetric cells for 800 h at 0.1 mA cm–2 without a short circuit. LiNi0.928Co0.072O2/LLZO-OH/Li full cells exhibit excellent stability at 0.1 C for 200 cycles. This work offers a novel low temperature sintering method to develop dendrite-free LLZO electrolytes for solid-state lithium metal batteries.