Stress and strain energy dynamics in Zn/VO2 battery electrodes under cyclic electrochemical loading

Irreversible cyclic strain and stress in battery electrodes during ion intercalation or deintercalation drives mechanical energy dissipation, accelerating lifecycle degradation. However, the lack of quantitative methods to assess this dissipation hinders a mechanistic understanding of mechanical behavior in electrochemical systems. Here, we present a theoretical framework integrated with operando strain measurements to quantify stress and strain energy evolution in practical heterogeneous composite electrodes, validated using a VO2-based zinc-ion battery cathode. Under assumptions of plane stress and elastic deformation, spatially resolved stress distributions and average stress or strain energy per cycle are derived and calculated for VO2-based cathodes during dynamic Zn2+ insertion or extraction. Experimental validation reveals that biphasic VO2 exhibits lower stress or strain energy magnitude than single-phase VO2 during prolonged cycling, correlating with its superior cycling stability.