Improved performance of vanadium redox battery using methylsulfonic acid solution as supporting electrolyte

Methylsulfonic acid (MSA) as supporting electrolyte for vanadium redox battery was studied and evaluated by thermal stability test, cyclic voltammetry, linear sweep voltammetry, and charge-discharge technique. The results show that the V(V)-MSA solution has better thermal stability than the sulfuric acid solutions, which may be due to the formation of VO(CH3SO3)2 to prevent further condensation. The diffusion coefficient of V(IV) in MSA can reach up to (0.94–1.52) × 10−6 cm2 s−1, much higher than that in H2SO4 solution (1.40–2.20 × 10−7 cm2 s−1). Polarization curves show the improved reaction kinetics of V(IV)/V(V) in MSA solution, lower charge transfer resistance (5.61 Ω), larger exchange current density (4.57 × 10−3 A cm−2), and rate constant (4.74 × 10−5 cm s−1) compared with the H2SO4 solution. The vanadium redox batteries with the MSA electrolytes demonstrated excellent reversibility and high energy efficiency (83.1%), 2.7% higher than that in H2SO4 solution. The preliminary exploration shows that MSA has a promising application prospect in vanadium redox battery and is worthy for further study.