chemical strain analysis of CNT/VOOH during zinc insertion in Zn-ion batteries

• Published in: Energy & environmental science Vol. 16; no. 1; pp. 467 - 4678
• Main Authors: Shi, Xiuling, Sun, Yuchuan, Weng, Yibo, Long, Xiaoying, Lei, Tongxing, Zhou, Jianli, Li, Deping, Zhang, Jin, Huang, Yan, Ci, Lijie, Li, Kaikai, Zhang, Tong-Yi
• Format: Journal Article
• Published: 11.10.2023
• ISSN: 1754-5692; 1754-5706
• DOI: 10.1039/d3ee01745a

Electrochemical ion insertion/extraction induces the periodical volume change, which causes fatigue and capacity decay of Zn-ion batteries, but the lack of quantitative understanding of the volume change remains a great challenge to the rational design of high-stability cathodes. Herein, we report an operando digital image correlation (DIC)-based technique applied to the investigation of the chemical strain of the CNT/VOOH composite cathode with pure VOOH for comparison. In combination with an electrochemical-mechanical coupling model, the chemical strain evolution with time (capacity) and residual chemical strain with cycle are quantified and the partial molar volumes of Zn 2+ in the two cathodes are estimated. The results indicate that the partial molar volume of Zn 2+ is obviously reduced by the introduction of CNTs, yielding smaller strains in the CNT/VOOH composite compared to that in pure VOOH, thereby conferring the long-term stability of CNT/VOOH. Specifically, the CNT/VOOH composite cathode delivers a high specific capacity of 322 mA h g −1 at 20 A g −1 and exhibits ultra-long cycle life at 10 A g −1 with 206 mA h g −1 retained after 8500 cycles. An operando DIC-based technique is developed to analyze the strain and partial molar volume of Zn 2+ in combination with an electrochemical-mechanical coupling model, which provides fundamental explanations for the enhanced cycling stability of AZIBs.