Electrochemical properties and hydrogen storage mechanism of perovskite-type oxide LaFeO3 as a negative electrode for Ni/MH batteries

Review: on rare-earth perovskite-type negative electrodes in nickel–hydride (Ni/H) secondary batteries

“…These reagents are mixed in distilled water and heated until the excess free water evaporates. Subsequently, the resulting viscous liquid is auto-ignited by putting it in a preheated plate at a temperature around 673 K. Subsequently the as-burnt powder is calcined at a temperature typically around 1200 K for 3 to 5 h. This method has been reported in numerous studies involving RE-perovskite-type oxides for applications in Ni/MH batteries [27,59,64,65]. For instance, Deng et al [59] prepared RE-perovskite-type oxides to built-up electrodes for Ni/MH cells using the combustion method.…”

“…The hydrogen absorption mechanism in RE-perovskite-type oxides is similar to that presented before for intermetallic alloys, where the storage of hydrogen atoms is given by the reduction of water at the interface electrolyte/active material. Hydrogen atoms are then captured within the structure of the RE-perovskite-type oxide to form a solid solution, i.e., a hydride compound [27,59,77]. Accordingly, the half-cell electrochemical reaction at the REperovskite-type negative electrode is:…”

“…3 Plot of the discharge capacity as a function of the cycle number in a La 1-x Sr x FeO 3 (x = 0.2: orthorhombic structure, x = 0.4: rhombohedral structure). Data adapted from [59] the absorption/desorption process [27,78]. In the charge process, the plateau is more notorious due to the formation of stable chemical bonds between protons and oxygen in the oxide.…”

“…This fact is attributed to the lower cost of perovskite-type oxides than conventional intermetallic alloys, due to its thermally stability, abundance, and comparatively active behavior [27][28][29]. RE-perovskitetype oxides are known not only to present proton conductivity at high temperatures and under hydrogen atmospheres, but also to have higher hydrogen solubility than other metal oxides.…”

“…In the last decade, rare-earth (RE) perovskite-type oxides (ABO 3 ), which are reported herein as hydrogen uptake materials [21][22][23][24][25][26][27][28], have been regarded to be one of the valuable alternatives as negative electrode materials in Ni/ MH batteries. This fact is attributed to the lower cost of perovskite-type oxides than conventional intermetallic alloys, due to its thermally stability, abundance, and comparatively active behavior [27][28][29].…”