Lu Bo, Song Yicheng, Zhang Qinglin, Pan Jie, Cheng Yang-Tse, Zhang Junqian
Shanghai Institute of Applied Mathematics and Mechanics, Shanghai University, Shanghai 200072, China and Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506, USA.
Department of Mechanics, Shanghai University, Shanghai 200444, China.
Phys Chem Chem Phys. 2016 Feb 14;18(6):4721-7. doi: 10.1039/c5cp06179b.
The crucial role of mechanical stress in voltage hysteresis of lithium ion batteries in charge-discharge cycles is investigated theoretically and experimentally. A modified Butler-Volmer equation of electrochemical kinetics is proposed to account for the influence of mechanical stresses on electrochemical reactions in lithium ion battery electrodes. It is found that the compressive stress in the surface layer of active materials impedes lithium intercalation, and therefore, an extra electrical overpotential is needed to overcome the reaction barrier induced by the stress. The theoretical formulation has produced a linear dependence of the height of voltage hysteresis on the hydrostatic stress difference between lithiation and delithiation, under both open-circuit conditions and galvanostatic operation. Predictions of the electrical overpotential from theoretical equations agree well with the experimental data for thin film silicon electrodes.
从理论和实验两方面研究了机械应力在锂离子电池充放电循环中电压滞后现象中的关键作用。提出了一种修正的电化学动力学巴特勒 - 沃尔默方程，以考虑机械应力对锂离子电池电极中电化学反应的影响。研究发现，活性材料表层的压应力会阻碍锂的嵌入，因此，需要额外的电过电位来克服由应力引起的反应势垒。理论公式表明，在开路条件和恒流操作下，电压滞后高度与锂化和脱锂过程中的静水压力差呈线性关系。理论方程对电过电位的预测与薄膜硅电极的实验数据吻合良好。
