Kinetics in a unique sodium borohydride regenerative fuel cell

ENVR 81

George H. Miley, ghmiley@uiuc.edu, Nie Luo, nluo@uiuc.edu, Xiaoling Yang, yangx2007@gmail.com, Kyu-Jung Kim, kyujung@illinois.edu, and Grant Kopec, gkopec@gmail.com. Department of Nuclear, Plasma and Radiological Engineering, University of Illinois at Champaign-Urbana, 100 NEL, 103 S. Goodwin Ave, Urbana, IL 61801
A unitized direct sodium borohydride regenerative battery-type fuel cell is being developed to compete with other advanced regenerative fuel cells and chemical batteries. In its discharged state, this cell contains an aqueous solution of sodium metaborate in both the anode and cathode sides. During recharge, the cell is designed to electrochemically produce sodium borohydride in the anode and hydrogen peroxide in the cathode. The work described here is focused on cell kinetics based on measurements of the species produced during recharge. Nuclear magnetic resonance spectroscopy and other supporting measurements are employed. Results confirm that sodium borohydride is electrochemically regenerated in aqueous solution via a one-step process from a solution of sodium metaborate at the anode. It is shown that an optimal pH of order 12-13 balances the stability of any sodium borohydride produced during recharge with the oxidizing species necessary for sodium borohydride oxidation during discharge.