Constructing Stable and Efficient Solid Electrolytes Based on Zirconium-Doping on Li₄Ti₅O₁₂ for Solid-State Lithium Metal Batteries

Solid-state lithium metal batteries (SSLMBs) represent a prime direction for next-generation high-energy-density storage technologies. As the central component for developing SSLMBs, current research focuses on designing solid-state electrolytes featuring high ionic conductivity and low electronic conductivity, along with low cost. However, great challenges are encountered. This work develops a composite solid electrolyte (CSE) consisting of a doped Li4Ti4.95Zr0.05O12 (LTZO1) and poly(vinylidene fluoride) (PVDF), which has a network structure that enables rapid ion conduction and electron blocking. Density functional theory calculations confirm that Zr doping can get a reduced energy barrier for Li+ transport, with ionic conductivity increasing from 0.228 mS cm–1 to 0.665 mS cm–1 and dramatically suppressing its electronic conductivity from 0.11 mS cm–1 to 2.4 × 10–6 S cm–1. The optimized CSE exhibits enhanced ionic conductivity from 0.171 mS cm–1 to 0.581 mS cm–1, further weakens electronic conductivity, and has a critical current density of up to 5.5 mA cm–2. These excellent properties make solid-state batteries such as Li|LTZO1|LiFePO4 and Li|LTZO1|NCM811 achieve good performance, including capacity and cycling. This study provides an effective strategy for preparing practical CSEs for SSLMBs.