Composite solid electrolytes have recently attracted widespread attention due to their acceptable lithium-ion (Li-ion) conductivity and suitable flexibility. However, isolated ceramic particles in composite electrolyte cannot provide continuous fast Li-ion transport channels. And the non-uniformity caused by particle agglomeration usually leads to a decrease in the performance of the composite electrolyte. Here, we design a “polymer in ceramic” composite electrolyte that combines three-dimensional Li_6.4La₃Zr₂Al_0.2O₁₂ (3D LLZAO) framework with polyethylene oxide (PEO)/LiTFSI (T-LAPL) via a template and solution method. In addition to the significantly enhanced Li-ion conductivity (2.51×10^-4 S cm^-1 at room temperature) and the high Li-ion transference number (t_Li+ =0.53), the T-LAPL composite electrolyte also exhibits improved thermal and electrochemical stability. Both symmetrical Li/T-LAPL/Li cells and LiFePO₄/T-LAPL/Li cells display excellent electrochemical performance. The repeated lithium stripping/plating process at 0.1 mA cm^-2 can keep stable for 400 hours without short circuit at room temperature. The assembled LiFePO₄ cell shows an initial discharge capacity of 165.9 mAh g^-1 at 0.2 C and the capacity can remain 80 % after 100 cycles. This high-performance composite electrolyte reveals a promising opportunity for the next-generation lithium batteries with high energy density and high safety.

复合固体电解质由于其可接受的锂离子（Li离子）导电性和合适的柔韧性而最近引起了广泛的关注。但是，复合电解质中孤立的陶瓷颗粒无法提供连续的快速锂离子传输通道。并且，由粒子团聚引起的不均匀性通常导致复合电解质的性能下降。在这里，我们设计了一种“陶瓷中的聚合物”复合电解质，该电解质通过模板和溶液将三维Li _6.4 La ₃ Zr ₂ Al _0.2 O ₁₂（3D LLZAO）骨架与聚环氧乙烷（PEO）/ LiTFSI（T-LAPL）结合在一起方法。除了显着增强的锂离子电导率（2.51×10 ^-4室温下为S cm ^-1）和高的锂离子迁移数（t _{Li +} = 0.53），T-LAPL复合电解质还具有改善的热稳定性和电化学稳定性。对称的Li / T-LAPL / Li电池和LiFePO ₄ / T-LAPL / Li电池均显示出出色的电化学性能。在0.1 mA cm ^-2处重复进行锂剥离/镀覆过程可保持稳定400小时，而在室温下不会发生短路。组装好的LiFePO ₄电池的初始放电容量为165.9 mAh g ^-1温度为0.2 C时，经过100次循环后容量可保持80％。这种高性能的复合电解质为具有高能量密度和高安全性的下一代锂电池提供了广阔的机遇。