Solid-state lithium batteries (SSLBs) using solid-state electrolytes (SSEs) have attracted much attention due to their satisfying safety and high energy density. Towards further practical development, insufficient room temperature ionic conductivity in garnet-type Li_6.5La₃Zr_1.5Ta_0.5O₁₂ (LLZTO) SSEs (usually ˂1×10⁻³ S‧cm⁻¹) remains a significant challenge and calls for a giant leap. In this work, a novel solid-state sintering strategy is employed by introducing La₂O₃ nanoparticles to promote the homogenous distribution of the grains and construct 3D continuous Li-ion transport networks along the grain boundaries. The La₂O₃ nanoparticles are regarded as the second phase to inhibit the abnormal grain growth (AGG) of LLZTO grains and reduce the voids defect to improve the relative density. The LaLiO₂ Li-ion conductor is synthesized by combining the excess La₂O₃ nanoparticles and the gas Li₂O, providing continuous ionic pathways and enhancing the Li-ion conductivity. The Li-ion conductivity reaches 1.12×10⁻³ S•cm⁻¹ (64 % higher than the pure LLZTO electrolyte) with a relative density of 98.1 %. The results presented here show that SSLBs with LiFePO₄ cathode achieve a superior stable cycling performance with a high discharge capacity of 128.8 mA•h•g⁻¹ and a Coulombic efficiency over 99% after 600 long-term cycles (0.5 C) at room temperature. The work provides a feasible solid-state sintering approach to creating SSEs with high performances for future applications of SSLBs.

使用固态电解质（SSE）的固态锂电池（SSLB）因其令人满意的安全性和高能量密度而备受关注。对于进一步的实际开发，石榴石型 Li _6.5 La ₃ Zr _1.5 Ta _0.5 O ₁₂ (LLZTO) SSE（通常为˂1×10 ^-3 S‧cm ^-1）的室温离子电导率不足仍然是一个重大挑战，需要大跃进。在这项工作中，通过引入 La ₂ O _3，采用了一种新颖的固态烧结策略。纳米粒子以促进晶粒的均匀分布，并沿晶界构建 3D 连续锂离子传输网络。La ₂ O ₃纳米颗粒被认为是抑制LLZTO晶粒异常晶粒生长（AGG）和减少空隙缺陷以提高相对密度的第二相。LaLiO ₂锂离子导体是通过将过量的 La ₂ O ₃纳米粒子与气体 Li ₂ O结合而合成的，提供连续的离子通路并提高锂离子的电导率。锂离子电导率达到1.12×10 ^-3 S•cm ^-1（比纯 LLZTO 电解质高 64%），相对密度为 98.1%。此处展示的结果表明，具有 LiFePO ₄正极的SSLB实现了优异的稳定循环性能，在室温下 600 次长期循环 (0.5 C) 后具有 128.8 mA•h•g ^-1的高放电容量和超过 99% 的库仑效率温度。这项工作提供了一种可行的固态烧结方法，可以为 SSLB 的未来应用创建具有高性能的 SSE。