全固态电池采用固态电解质取代液态电解液，可解决传统锂电池安全性问题，同时有望使用锂金属作为负极材料来提高电池的能量密度。然而，全固态电池面临诸多挑战，比如固态电解质较低的离子电导率、复合正极构建、电极与电解质固-固界面等问题。本论文围绕硫化物电解质，从其制备与表征、电化学反应机理、复合正极设计等方面对全固态电池性能的影响进行了系统的研究。研究了固相烧结工艺对Li6PS5Cl电解质的相组成、锂离子传导特性的影响。550°C烧结10 min 即可获得室温离子电导率高于3 mS cm-1的电解质。以硫-多壁碳纳米管（MWCNTs）-Li6PS5Cl复合物作为正极，锂铟合金作为负极组装全固态电池，在0.176 mA cm-2下循环首圈实现了1850 mAh g-1的超高放电容量，50圈后容量为1393 mAh g-1。实验揭示了Li6PS5Cl电解质具有电化学反应活性。研究了不同结晶度的硫化物电解质（SE）对全固态电池性能的影响。以In | SE | LiCoO2@LiNb0.5Ta0.5O3为模型电池，结果表明，使用玻璃或玻璃陶瓷电解质相比其对应的晶态电解质，显示出更好的电化学性能。这主要归因于使用玻璃或玻璃陶瓷电解质的正极中机械接触失效较小。基于固相烧结工艺制备高离子电导率（4 mS cm-1）的Li6PS5Cl0.5Br0.5（LPSCB）电解质，构建了In/LiIn | LPSCB | LPSCB-MWCNTs固态电池。通过循环过程中LPSCB的电化学分解，在LPSCB/MWCNTs两相复合正极中原位形成了活性物质、有效的离子和电子传导路径。该LPSCB基全固态电池在室温大电流密度（0.885 mA cm-2，~0.7 C）下循环1000余次仍可放出1.24 mAh cm-2的面容量，容量保持率94%。也可以实现室温12.56 mAh cm-2的高面容量。通过一系列的分析表征技术，揭示了LPSCB作为电极活性物质在循环中的电化学反应机理。为了制备薄电解质层，将聚偏氟乙烯（PVDF）引入到Li6PS5Cl电解质基体中，从而制备出离子电导率约为1 mS cm-1、厚度约为100 μm的Li6PS5Cl/PVDF复合电解质膜。Li6PS5Cl颗粒之间的孔隙被PVDF填充，可以缓解锂枝晶在Li6PS5Cl电解质中的生长。

All-solid-state batteries (ASSBs) are expected to achieve high safety by replacing liquid electrolyte with nonflammable solid electrolytes (SEs). In addition, ASSBs with high energy density may also be achieved due to enabling the utilization of lithium-metal as anode. However, the state-of-the-art ASSBs face many challenges, such as low ionic conductivity of SEs, composite cathode design, and solid electrode-solid electrolyte interface issues. This thesis mainly focuses on the preparation and characterization of sulfide SEs, the electrochemical reaction mechanism of SEs, the design of composite cathode, and the influence of sulfide SEs with different crystallinity on the performance of ASSBs.First of all, the effects of sintering temperature and durations on the phase, ionic conductivity and activation energy of Li6PS5Cl (LPSCl) have been investigated. A high ionic conductivity of over 3 mS cm-1 can be obtained by sintering at 550°C for just 10 min. The ASSB with nano sulfur-multiwall carbon nanotubes (MWCNTs)-LPSCl composite as cathode and Li-In alloy as anode delivers an initial high discharge capacity of 1850 mAh g-1 at 0.176 mA cm-2 at room temperature (RT), and the capacity remains 1393 mAh g-1 after 50 cycles. In addition, the decomposition products of LPSCl is proved to show electrochemical reaction activity. The influence of sulfide SEs with the same stoichiometry but different crystallinity on the performance of ASSBs is systematically studied. In/InLi | SE | LiCoO2@LiNb0.5Ta0.5O3 ASSB cells with glass or glass-ceramic SEs show higher Coulomb efficiency, slower increase of interfacial resistance, and better cycling and rate performance when compared to cells built with their crystalline analogues. This is mainly due to the less contact loss in the composite cathode with glass/glass-ceramic SEs. Based on the Li6PS5Cl0.5Br0.5 (LPSCB) SE with high ionic conductivity (4 mS cm-1) prepared by the solid-state sintering, the In/LiIn | LPSCB | LPSCB-MWCNTs ASSB is constructed. By electrochemical decomposition of LPSCB during the first discharge process, active material, effective ion and electron conduction paths are formed in situ in the LPSCB/MWCNTs two-phase composite cathode. The LPSCB-based ASSB still delivers a high areal capacity of 1.24 mAh cm-2 at a high current density (0.885 mA cm-2, ~0.7 C) after around 1000 cycles with a capacity retention of 94%. A high areal capacity of 12.56 mAh cm-2 is also achieved. Comprehensive characterization reveals a co-redox process of two redox-active elements during cycling. In order to prepare a thin SE layer, polyvinylidene fluoride (PVDF) is introduced into the LPSCl electrolyte matrix to prepare a LPSCl/PVDF composite electrolyte membrane with a high ionic conductivity of around 1 mS cm-1 and a thickness of about 100 μm. The pores between the LPSCl particles are filled with PVDF, which can alleviate the lithium dendrite growth in the LPSCl SE.