Uncovering the effect of ion exchange membrane on capacity decay and efficiency for all-vanadium redox flow battery by modeling analysis

ABSTRACT

During the long-term charge–discharge cycle, the vanadium permeability of membrane has a significant impact on the capacity and efficiency of the all-vanadium redox flow battery (VFB). Fundamentally, the diffusion of vanadium ions will enhance the self-discharge reaction, resulting in an imbalance in the state of charge of the electrolytes of the two half-cells and a subsequent decrease in capacity. In order to predict the capacity decay and efficiencies of VFBs in the long-term cycle caused by the diffusion of vanadium ions, an electrochemical model of VFB is established on the basis of mass conservation. In this paper, VFBs with five commercialized membranes including cation exchange membrane and anion membrane were investigated at varied densities. Simulation results prove that the diffusion coefficient of vanadium ions has a significant effect on the capacity decay of VFB and the capacity decay can be to some extent alleviated by increasing the charge–discharge current. Therefore, this simulated model can be an excellent guidance for VFB practical operation.

KEYWORDS:

• All-vanadium flow battery
• vanadium permeability
• modeling analysis
• capacity decay and efficiency
• ion exchange membrane

Acknowledgments

This work was supported in part by the National Natural Science Foundation of China under Grant 52074064 and Grant 62173073; in part by the National Key Research and Development Program of China under 2020AAA0109203; in part by the Fundamental Research Funds for Liaoning Natural Science Foundation, China, under Grant 2019-MS-120; in part by the Fundamental Research Funds for the Central Universities, China under Grant N2104026, Grant N2018008, and Grant N2001002; in part by Institute of Metal Research, Chinese Academy of Sciences.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [52074064] and [62173073]; National Key Research and Development Program of China [2020AAA0109203]; Fundamental Research Funds for Liaoning Natural Science Foundation, China [2019-MS-120]; Fundamental Research Funds for the Central Universities, China [N2104026]; [N2018008]; and [N2001002]; Institute of Metal Research, Chinese Academy of Sciences.