A Non‐Isothermal Dynamic Model for Vanadium Redox Flow Batteries With Gravitational Loss Analysis

Vanadium redox flow batteries (VRFB) are promising for long‐duration and large‐scale energy storage owing to their high safety, long cycle life, and independently scalable power and energy capacities. However, most existing dynamic models rely on isothermal or lumped‐parameter assumptions, which neglect gravitational losses, temperature‐dependent electrolyte properties, and heat transfer in pipelines. These simplifications limit their accuracy in representing practical VRFB operation, particularly in large‐scale energy storage systems. This study develops a non‐isothermal dynamic model for VRFB by coupling electrochemical, mass transfer, hydraulic, and thermal processes. Gravitational work is incorporated into the hydraulic loss formulation, while electrolyte density and viscosity are treated as temperature‐dependent time‐varying parameters. A three‐zone thermal model covering the storage tanks, transfer pipelines, and stack is further established to describe heat generation, dissipation, and intercomponent heat exchange. Experimental validation under different currents and flow rates showed good agreement between the simulated and measured voltage responses, with a maximum absolute error of 4.28%. The simulated temperatures also closely reproduced the measured thermal trends at the stack, tank, and pipelines. Furthermore, comparative analysis at different pipeline elevation heights showed that the pump‐loss current increased with height, confirming the contribution of gravitational head to parasitic losses. Sensitivity analysis further elucidated the effects of current and flow rate on voltage response and Coulombic efficiency. The proposed model provides a basis for state monitoring, thermal management, grid‐oriented control, and scale‐up analysis of VRFB energy storage systems.