新型高比能量全固态钠金属电池的设计与界面稳定性调控

All-solid-state sodium metal batteries are one of the most promising energy storage systems due to their advantages of high safety, high energy density and low cost. However, so far, the development and application of the current all-solid-state sodium metal batteries is in slow pace. The main bottleneck is that the current electrolyte systems show poor stability towards sodium metal anode and incompatibility with high-specific-energy cathodes. In this project, we innovatively design a new oxy-chloro-sulfide solid-state electrolyte system. The new electrolyte shows unique microstructural character of negligible grain boundary and excellent (electro)chemical stability towards sodium metal, which is expected to address the scientific problems for the current electrolyte systems (oxide electrolytes suffer from the short-circuiting due to the sodium dendrite penetration along the grain boundary; sulfide ones experience decomposition due to the chemical reaction with sodium metal) and realizes the stable cycling of sodium metal anode and running of room-temperature sodium-sulfur battery with high specific energy by further designing novel three-dimensional structured sodium metal anode and sulfur composite cathode. In addition, the relationship between the composition, microstructure and performance of the new solid-state electrolytes will be revealed by the ex-situ material characterization techniques; the interfaces between the electrode and electrolyte will be deeply analyzed and effectively optimized through the in-situ electrochemical techniques, which will pave the way for the development and applications of the all-solid-state batteries.

全固态钠金属电池因其高安全性、高能量密度和低成本等优点，是最有前景的储能体系之一。然而，当前全固态钠金属电池的发展和应用进程缓慢。主要的瓶颈是当前的电解质体系对钠金属负极稳定性差并且与高比能量的正极不兼容。本项目创新性地设计出一种新型的氧-氯-硫化物固态电解质体系，这种电解质体系具有独特的基本无晶界的微结构特征和对钠金属优异的电(化学)稳定性，有望解决目前电解质体系(氧化物因为晶界诱导的枝晶刺穿短路以及硫化物与钠金属反应分解)的科学问题，同时通过设计新颖的三维结构的钠金属负极以及硫复合正极，实现钠金属负极长时间稳定循环以及高比能量室温钠硫电池的运行。本项目还将借助非原位的材料表征技术探索电解质的组成，微结构与性能之间的关系以及原位的电化学技术深入分析并优化电极/电解质的界面，为全固态电池的发展与应用奠定基础。

全固态钠金属电池是最有前景的高安全和低成本储能体系之一。其应用的关键瓶颈是传统电解质对钠金属负极稳定性差并且与高比能量的正极不兼容。本项目设计并成功合成出一种新型的氧-硫化物基玻璃固态电解质体系，兼具了氧化物和硫化物体系固态电解质的优点。这种新型的固态电解质体系不仅可以匹配钠金属负极以及高比容量的硫正极，达到了项目的预期目标，而且表现出多个独特的性质：室温低压力下实现晶界基本无缺陷、高致密度和高机械强度。多种材料表征技术和(电)化学表征技术揭示了氧-硫化物基玻璃固态电解质的多尺度结构特征和对金属钠在化学-机械-电化学三方面的界面稳定机制。进一步地，在电池性能方面取得了多个突破性进展。基于氧-硫化物基玻璃固态电解质，钠金属对称电池表现出目前文献报道的最高的临界电流密度，最优的循环稳定以及匹配硫正极，实现了近室温下稳定工作且具有超高能量密度的全固态钠金属-硫电池的组装和运行，展现出了很好的实际应用潜力。