多场耦合作用对陶瓷基复合固体电解质相界面稳定性的影响机制及调控机理研究

如何提高固体电解质的离子电导率是新一代全固态锂电池发展的技术瓶颈之一。目前，在材料性能上取长补短的复合固体电解质的开发已成为未来的技术发展趋势。开发高性能复合固体电解质的一个关键问题就是如何调控锂离子在不同电解质组元之间的输运稳定性。为了解决这个难题，本项目拟通过界面原位分析技术、理论模拟计算和应力/应变在线监测等方法对石榴石/反钙钛矿型陶瓷基复合电解质固-固相界面的稳定性开展研究。通过调节充放电电流密度、元素扩散浓度梯度和应力/应变梯度等参数的方法，考察陶瓷基复合电解质相界面的组分、结构和应力/应变状态在不同充放电条件下的演化规律，寻找影响相界面离子输运稳定性的关键因素，揭示陶瓷基复合电解质相界面的电化学阻抗在多场耦合（电场、扩散场和应力场）作用下的优化方法，阐明多场耦合模型调控对沿石榴石型电解质晶界生长的锂枝晶的抑制机理，为高性能、长寿命的全固态锂电池复合电解质的开发提供科学依据。

One of the bottlenecks for all-solid-state lithium batteries is to improve the ionic conductivity of solid electrolytes. Recently, composite solid electrolytes with complementary advantages become their developing trend among future techniques. One of the key problems for composite solid electrolytes is to regulate the transporting stability of lithium ions between different electrolyte components. In order to solve this problem, this project aims at the researches of the interface (solid-solid) stability of garnet/anti-perovskite ceramic electrolytes, which can be characterized by in-situ interface analysis, theoretical simulation, stress/strain on-line monitoring etc. By developing the new methods such as adjusting charge-discharge current density, element diffusion concentration gradient and stress-strain gradient, the evolution of the ceramic composite electrolyte interface can be well studied, including the electrolyte component, structure and stress-strain state. In addition, the key factors that affect the ion transport at the interface can be found, and the optimized methods of electrochemical impedance for the solid electrolytes will be revealed under the multi-coupling field (electric field, diffusion field and stress field). Also, these new methods help to clarify the inhibition mechanism of lithium dendrite growth for garnet electrolyte with multi-field coupling models. This project provides new insights and scientific basis for the high-performance and long-life lithium batteries with all-solid-state composite electrolytes.