非晶硅负极材料在锂电池快速充电条件下极易发生力学退化，导致不可逆容量衰退，缩短高性能锂电池使用寿命。快速充电条件下非晶硅中原子重新排列并极易产生微观缺陷，但传统连续介质力学模型未引入材料微观缺陷，无法准确分析电极材料的应力演化过程和锂化动力学过程。为解决这一问题，本项目采用自由体积定义非晶硅负极材料在锂化过程中的微观缺陷，并以此为基础建立新的力学-化学耦合模型。具体研究内容叙述涵括三个方面：（1）研究锂化过程中自由体积改变对塑性流动的影响，确定微观自由体积和宏观塑性应变率之间的关系；（2）将锂化速率考虑在内，研究微观自由体积变化规律；（3）研究锂化、应力演化和自由体积变化之间的耦合关系，建立新的粘塑性力化学耦合模型，并通过实验验证其正确性。本项目为非晶硅负极材料的结构设计提供必要的基础性科学依据，推动解决其在快速充电条件下力学退化的难题。

It is known that the mechanical degradation tends to happen in amorphous silicon electrode during the processes of fast charging. Fast charging may lead to the atoms rearrangement, and the micro-defect in amorphous silicon electrode. The effect of micro-defect is neglected in the conventional continuum mechanics, so the stress evolution and lithiation process is not precisely analyzed. In order to overcome this issue, the concept of free volume is introduced to define the micro-defect in amorphous silicon during the process of lithiation, which can be used to establish a new chemo-mechanical model. The specific research content includes three aspects: (1) The relationship between free volume and plastic flow is analyzed, and the relationship between free volume and plastic strain rate are determined. (2) The variation of free volume is investigated with considering the effect of lithiation rate. (3) In order to established new chemo-mechanical coupling model, the coupling relation among the lithiation process, stress evolution process and variation of free volume is studied. The provided theoretical model are validated by simple experiment for the application of high performance electrode material. This project can provide scientific basis for the structural design of amorphous silicon electrode, which may solve the issue of mechanical degradation during the process of fast charging.