锂离子电池硅碳负极材料变形实时原位表征及失效机理研究

锂离子电池具有高能量密度、高功率、低自放电率、无记忆效应等优点，已成为国家能源发展战略的重要支柱之一。硅碳负极材料变形失效和分层断裂已成为发展更高容量、更长寿命锂离子电池的重要瓶颈。发展不同原理的电极变形实时原位实验技术和实验装备是研究硅碳负极材料力学行为和提升锂离子电池性能的重要途径。在项目组的工作基础上，本申请项目拟进一步发展基于数字图像相关方法的锂离子电池硅碳负极变形失效的实时原位表征技术和实验系统；制备硅碳负极材料和耐化学反应的特殊散斑材料，在不同工作温度和充放电条件下实现硅碳负极变形失效实时原位表征；完善多层结构硅碳负极材料热-化-力多场本构模型，建立硅碳负极变形断裂失效与锂离子电池性能退化的关联，系统分析热-化多场耦合作用下硅碳负极材料变形、应力演变及失效机理，为新型锂离子电池安全性、可靠性和耐用性提供重要实验依据。

Lithium-ion batteries (LIBs) have the advantages of high energy density, high power, low self-discharge rate and no memory effect. They have become one of the important pillars of national energy development strategies. The deformation failure and layered fracture of silicon-carbon composite anode materials have become an important bottleneck in the development of LIBs with higher capacity and longer life. The developments of in-situ experimental measurement techniques and equipment of electrode deformation in LIBs play an important role in studying the mechanical behaviors of silicon-carbon anodes and enhancing the performance of LIBs. On the basis of our previous works, we will further develop an in-situ measurement technique and system of deformation failure of silicon-carbon anodes of LIBs based on digital image correlation, and prepare the semi-battery of silicon-carbon anode materials and special speckle materials resistant to chemical reaction, and then perform in-situ characterizations of deformation failure of silicon-carbon anodes under different operating temperatures and charge-discharge cycling. We further propose the thermo-chemo-mechanical coupling constitutive model of multilayer silicon-carbon anode materials, and establish the relationship between the deformed fracture failure of silicon-carbon anodes and performance degradation of LIBs. Finally, we will systematically analyze the deformation, stress evolution and failure mechanisms of multilayer structure silicon-carbon anode materials under thermo-chemical coupling conditions. The results can provide the related important guidance for the safety, reliability and durability capabilities of new LIBs.