Contents lists available at ScienceDirect Journal of Power Sources journal homepage: www.elsevier.com/locate/jpowsour In-situ characterizations of chemo-mechanical behavior of free-standing vanadium pentoxide cathode for lithium-ion batteries during discharge- charge cycling using digital image correlation Weiguo Mao a , Zhuo Wang a , Caisheng Li a , Xiaoxue Zhu a , Cuiying Dai a,* , Haoyong Yang a , Xi Chen b,** , Daining Fang c a School of Materials Science and Engineering, Xiangtan University, Hunan, 411105, China b Department of Earth and Environmental Engineering, Columbia University, New York, 10027, USA c Institute of Advanced Structure Technology, Beijing Institute of Technology, Beijing, 100081, China HIGHLIGHTS The free-standing nanobelts structure V 2 O 5 cathodes were successfully syn- thesized. An in-situ and non-contact strain measurement system with digital image correlation. Heterogeneous strain features of V 2 O 5 cathode were successfully in-situ monitored. The corresponding stress evolutions of V 2 O 5 cathode were systematically discussed. The results are crucial to reveal the chemo-mechanical mechanisms of V 2 O 5 cathode. GRAPHICAL ABSTRACT ARTICLE INFO Keywords: Vanadium pentoxide In-situ measurement Heterogeneous strain Digital image correlation Chemo-mechanical coupling mechanism ABSTRACT The free-standing V 2 O 5 nanobelts cathodes for lithium-ion batteries are synthesized through hydrothermal re- action followed by anneal treatments and vacuum ltration deposition. The well cycling performances of the electrode were veried by battery test system. The microstructure and surface morphologies of the V 2 O 5 elec- trode before and after discharge-charge cycles were analyzed by X-ray diraction and scanning electron mi- croscope, respectively. The evolutions of strain elds of free-standing V 2 O 5 electrodes are in-situ measured by digital image correlation technique. The heterogeneous features of in-plane strains of V 2 O 5 electrode surface in macro-scales are characterized and systematically discussed as a function of test time (or voltage). Given the eect that the elastic modulus is dependent on the concentration and cycling number, the evolutions of in-plane stresses of V 2 O 5 cathodes during discharge-charge cycling are estimated using a chemo-mechanical constitutive equation. The inuences of chemical and mechanical components on in-plane stresses are extracted and dis- cussed, respectively. The results are crucial to further reveal the chemo-mechanical coupling failure mechanism of V 2 O 5 cathode and optimize the electrode structure of lithium-ion battery systems. https://doi.org/10.1016/j.jpowsour.2018.09.047 Received 7 March 2018; Received in revised form 15 July 2018; Accepted 16 September 2018 * Corresponding author. ** Corresponding author. E-mail addresses: daicuiying@126.com (C. Dai), xichen@columbia.edu (X. Chen). Journal of Power Sources 402 (2018) 272–280 0378-7753/ © 2018 Elsevier B.V. All rights reserved. T