Development of highly stable and active intermetallic Pt-alloyed catalysts for the production of V3.5+ electrolyte in the vanadium redox flow batteries

Abstract

Vanadium based battery is considered one of the most promising candidates to overcome the limitations of lithium ion battery in large-scale energy storage systems. However, the high manufacturing cost of the vanadium electrolyte has been hindered to commercialize. Although the catalytic production of vanadium electrolyte was reported, with an organic reducing agent such as formic acid is considered as a promising method, the continuous production of vanadium electrolyte is still difficult owing to the limited catalyst durability. Herein, we present the highly durable and active intermetallic Pt-alloyed catalysts, i.e., L12-Fe0.25Pt0.75/C and L12Co0.25Pt0.75/C, for the catalytic production of V3.5+ electrolyte. In the catalytic test of electrolyte production, the intermetallic L12-Fe0.25Pt0.75/C showed nearly 3 times higher activity than the commercial Pt/C catalyst. In the catalyst durability test, on the other hand, the intermetallic L12Co0.25Pt0.75/C showed only 3 % decrease of initial activity whereas the intermetallic L12-Fe0.25Pt0.75/C and commercial Pt/C exhibited ca. 9 % and ca. 20 % decrease of initial activity, respectively, for one hundred times continuous electrolyte production test. Among the catalysts tested, the intermetallic L12-Fe0.25Pt0.75/C showed the highest initial catalytic activity while the L12Co0.25Pt0.75/C exhibited the strongest catalyst durability. In terms of catalytic activity and stability, the intermetallic L12Co0.25Pt0.75/C was found to be an efficient catalyst for the practical production of V3.5+ electrolyte.