Lithium-ion solid-state batteries with spinel Li4Ti5O12 (LTO) electrodes have significant advantages, such as stability, long life, and good multiplication performance. In this work, the LTO electrode was obtained by the atmospheric plasma spraying method, and a composite solid electrolyte was prepared by in situ ultraviolet (UV) curing on the LTO electrode. The composite solid electrolyte was designed using a soft–hard combination strategy, and the electrolyte was prepared into a composite of a poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) flexible structure and high-conductivity Li1.3Al0.3Ti1.7(PO4)3 (LATP) hard particles. The composite electrolyte exhibited a good ionic conductivity up to 0.35 mS cm−1 at 30 °C and an electrochemical window above 4.0 V. In situ and ex situ electrolytes were assembled into LTO//electrolyte//Li solid-state batteries to investigate their impact on the electrochemical performance of the batteries. As a result, the assembled Li4Ti5O12//in situ electrolytes//Li batteries exhibited excellent rate of performance, and their capacity retention rate was 90% at 0.2 mA/cm2 after 300 cycles. This work provides a new method for the fabrication of novel advanced solid-state electrolytes and electrodes for applications in solid-state batteries.

固态电池因其优异的性能备受关注，但是与传统的液态电池相比，离子传输能力偏弱，原因是固-固界面离子传输困难。本文制备了以聚偏氟乙烯-六氟丙烯（PVDF-HFP）为基的固态电解质膜，并探究PVDF-HFP 和增塑剂乙氧基化三羟甲基丙烷三丙烯酸酯（ETPTA）质量比例为1.0∶0.3、1.0∶0.4、1.0∶0.5 时对电解质膜离子传输的影响，并组装成以磷酸铁锂为正极、锂片为负极的固态电池，研究其电化学性能。研究发现：当PVDF-HFP 和ETPTA 比例为1.0∶0.4 时，锂离子迁移数达0.89，电化学窗口可达4 V，离子电导率达到8×10-5 S/cm，表现出良好的稳定性。将比例为1.0∶0.4 的电解质膜装配成固态电池，经过激活之后，首先在0.1 C 的倍率下进行测试，首圈充电比容量为133 mA·h/g，首圈放电比容量为129 mA·h/g；在20 圈循环测试后，放电比容量也能保持在120 mA·h/g 以上，容量保持率为92%。

Gel electrolytes for lithium-ion batteries continue to replace the organic liquid electrolytes in conventional batteries due to their advantages of being less prone to leakage and non-explosive and possessing a high modulus of elasticity. However, the development of gel electrolytes has been hindered by their generally low ionic conductivity at room temperature and high interfacial impedance with electrodes. In this paper, a poly (vinylidene fluoride)-hexafluoropropylene copolymer (PVdF-HFP) with a flexible structure, Li6PS5Cl (LPSCl) powder of the sulfur–silver–germanium ore type, and lithium perchlorate salt (LiClO4) were prepared into sulfide gel composite electrolyte films (GCEs) via a thermosetting process. The experimental results showed that the gel composite electrolyte with 1% LPSCl in the PVdF-HFP matrix exhibited an ionic conductivity as high as 1.27 × 10−3 S·cm−1 at 25 °C and a lithium ion transference number of 0.63. The assembled LiFePO4||GCEs||Li batteries have excellent rate (130 mAh·g−1 at 1 C and 54 mAh·g−1 at 5 C) and cycling (capacity retention was 93% after 100 cycles at 0.1 C and 80% after 150 cycles at 0.2 C) performance. This work provides new methods and strategies for the design and fabrication of solid-state batteries with high ionic conductivity and high specific energy.