A ceramic solid electrolyte of Li_1.5Al_0.5Ge_1.5(PO₄)₃ (LAGP) with high ionic conductivity (4.28 × 10⁻⁴ S cm⁻¹ at 30 °C) and low activation energy (0.25 eV) is prepared by a three-step method, and the interfacial properties of the ceramic solid electrolyte are further modified by an in-situ polymerization strategy with the formation of a gel-polymer electrolyte with the thickness of 8.85 μm on the surface of LAGP. The presence of the gel-polymer electrolyte on the surface of LAGP inhibits the side reactions and the growth of lithium dendrites, as evidenced by the stable cycling of the lithium symmetric cells with the modified LAGP solid electrolyte for 1000 h at 25 °C. In addition, the high ionic conductivity and the stable interface of the modified LAGP solid electrolyte enable the solid-state lithium battery with a LiFePO₄ cathode, exhibiting superior electrochemical performances which can run stably at 25 °C with initial discharge specific capacity of 159.8 mAh g⁻¹ at 0.1C.

具有高离子电导率（4.28 × 10 ^-4 S cm ^{-1 ）的 Li} _1.5 Al _0.5 Ge _1.5 (PO ₄ ) ₃ (LAGP)陶瓷固体电解质通过三步法制备低活化能（0.25 eV）的陶瓷固体电解质，并通过原位聚合策略进一步修饰陶瓷固体电解质的界面性能，形成凝胶-聚合物电解质LAGP表面的厚度为8.85 μm。LAGP 表面上凝胶聚合物电解质的存在抑制了副反应和锂枝晶的生长，锂对称电池与改性 LAGP 固体电解质在 25°C 下 1000 小时的稳定循环证明了这一点。_{此外，改性LAGP固体电解质的高离子电导率和稳定的界面使LiFePO 4}的固态锂电池成为可能正极，表现出优异的电化学性能，可在 25 °C 下稳定运行，在 0.1C下的初始放电比容量为 159.8 mAh g ^{-1 。}