Catalytic activity of La1−xSrxCoO3−δ (x = 0–1) for aqueous lithium-air rechargeable batteries

Abstract We investigated the applicability of La 1− x Sr x CoO 3− δ (LSCO) as an oxygen electrode catalyst for aqueous lithium-air batteries using cyclic voltammetry (CV) and polarization measurements with a gas diffusion electrode (GDE). The electrolyte was a concentrated aqueous solution of LiCl (10.0 mol dm − 3 ) and LiOH (2.0 mol dm − 3 ). The catalyst samples were synthesized using conventional solid state synthesis and ground in a ball mill to achieve a uniform particle size. LSCO exhibited a perovskite-type structure up to x = 0.9, while x = 1 showed a brownmillerite-type structure. CV measurements were performed over a potential range of 0.1 V to 1.7 V vs. RHE to study the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). ORR activity was low, but OER activity was high in Sr-rich compositions ( x = 0.8 to 1.0). Within this range, oxide ion insertion into the structure for catalyst was confirmed, which is related to the high OER activity. Cycling degradation occurred due to the wide potential range scan; however, LSCO ( x = 0.9) remained relatively stable. Its OER activity was comparable to highly active catalysts, such as Sr 3 Co 2 O 7 and La 3 Co 2 O 5 Cl 2 . We evaluated the gas diffusion electrode (GDE) using the LSCO ( x = 0.9) electrode. Compared to Ketjenblack (KB), which is commonly used as the oxygen electrode in lithium-air batteries, the LSCO ( x = 0.9) electrode exhibited lower overpotentials for both ORR and OER. Aqueous lithium-air batteries that used the LSCO ( x = 0.9) electrode demonstrated low overpotentials and good cycling performance.