Ion Selectivity and Stability Enhancement of SPEEK/Lignin Membrane for Vanadium Redox Flow Battery: The Degree of Sulfonation Effect

Jiaye Ye; Xuechun Lou; Chun Wu; Sujuan Wu; Mei Ding; Lidong Sun; Chuankun Jia

doi:10.3389/fchem.2018.00549

Ion Selectivity and Stability Enhancement of SPEEK/Lignin Membrane for Vanadium Redox Flow Battery: The Degree of Sulfonation Effect

Front Chem. 2018 Nov 12:6:549. doi: 10.3389/fchem.2018.00549. eCollection 2018.

Authors

Jiaye Ye^{1

2}, Xuechun Lou¹, Chun Wu¹, Sujuan Wu², Mei Ding^{1

3}, Lidong Sun^{2

3}, Chuankun Jia^{1

3}

Affiliations

¹ College of Materials Science and Engineering, Changsha University of Science and Technology, Changsha, China.
² State Key Laboratory of Mechanical Transmission, School of Materials Science and Engineering, Chongqing University, Chongqing, China.
³ National Engineering Laboratory of Highway Maintenance Technology, Changsha University of Science & Technology, Changsha, Hunan, China.

Abstract

A membrane of high ion selectivity, high stability, and low cost is desirable for vanadium redox flow battery (VRB). In this study, a composite membrane is formed by blending the sulfonated poly (ether ether ketone) with lignin (SPEEK/lignin), and optimized by tailoring the degree of sulfonation. The incorporation of lignin into the SPEEK matrix provides more proton transport pathway and meanwhile adjusts the water channel to repulse vanadium ions. The VRB cells assembled with the composite membranes exhibit high coulombic efficiency (~99.27%) and impressive energy efficiency (~82.75%). The cells maintain a discharge capacity of ~95% after 100 cycles and ~85% after 200 cycles at 120 mA cm^-2, much higher than the commercial Nafion 212. The SPEEK/lignin composite membranes are promising for application in VRB system.

Keywords: SPEEK/lignin composite membrane; Sulfonated poly(ether ether ketone); degree of sulfonation; ion selectivity; vanadium flow battery.