Hydrogen storage in a rare‐earth perovskite‐type oxide La _0.6 Sr _0.4 Co _0.2 Fe _0.8 O ₃ for battery applications

Abstract

Abstract Recently, rare‐earth perovskite‐type oxides with the general formula ABO 3 (A rare earth element, B transition metal, O oxygen) are regarded as promising materials for Ni/oxide batteries due to their hydrogen storage ability. In the present study, the hydrogen storage properties of the rare‐earth perovskite‐type oxide La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 were evaluated in alkaline solution and at various temperatures. The hydrogen storage properties were investigated electrochemically by applying galvanostatic charge/discharge currents. Electrochemical pressure–composition–temperature isotherms were constructed using the Nernst equation. The exchange current density and proton hydrogen diffusion coefficient were calculated using linear polarization measurements and the potential‐step method, respectively. Interestingly, the maximum hydrogen absorption capacity, re‐calculated from the electrochemical capacity, is 1.72 wt% at 333 K and 6 mol·L −1 KOH. In addition, the hysteresis value, calculated from pressure–composition–temperature isotherms, was 429 J·mol −1 at 333 K, while the self‐discharge rate was about 25% after 24‐h storage at open circuit and at 333 K.