The mechanical properties of battery electrodes are crucial for the cycling lifespan of batteries.Meanwhile,the Young's modulus of the electrode and partial molar volume of the lithium electrode are key factors that affect the mechanical properties of battery electrodes.The present work mainly focuses on the mechanical properties of lithium-ion batteries with the Cu6Sn5 film electrode,in which the Young's modulus of Cu6Sn5 and the partial molar volume of lithium electrodes are unclear yet.We combine the experiments and the algorithm of machine learning to obtain the two parameters mentioned above.We prepared the Cu6Sn5 film on the Si substrate by Magnetron sputtering.After that,we used a multi-beam optical sensor to measure the in-situ curvature of Cu6Sn5 films of negative electrode during the charge-discharge process through the established in-situ curvature measurement system and electrochemical testing methods.The measurement results indicate that the curvature exhibits periodic changes starting from the second cycle of electrochemical cycling,and the elastic deformation mainly occurs during the discharge(lithium insertion)processes,while the inelastic deformation mainly occurs during the charging(lithium desertion)processes.The partial molar volume of lithium and the Young's modulus of Cu6Sn5 in the linear elastic process were taken as hyperparameters and the optimal value of the hyperparameters were obtained by limiting the value range of the hyperparameters within the TPE algorithm of Bayesian optimization.As a result,the Young's modulus of Cu6Sn5 is 140.149GPa and the partial molar volume of lithium in Cu6Sn5 is 2.787 cm3/mol.Our work is helpful for the theoretical modeling research of Cu6Sn5 film electrodes and provides a framework for the study of the mechanical and electrochemical coupling behavior of other batteries.
关键词
Cu6Sn5薄膜电极/多光束光学传感器/原位曲率测量/树状结构Parzen估计算法
Key words
Cu6Sn5 film electrode/multi-beam optical sensor/in-situ curvature measurement/Tree-structured Parzen Estimator
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