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

Abstract

Rare-earth perovskites-type oxides are compounds with the general formula ABO 3 . There are many industrial and research applications related to their properties such as photocatalytic activity, magnetism, or pyroferro and piezo-electricity, and interest in these compounds in the field of energy storage and conversion is growing. Rare-earth perovskite-type oxides may be used in nickelmetal hydride (Ni/MH) battery technology because these materials may store hydrogen in strong alkaline environments, and also because of their abundance and low cost. In this review, the use of rare-earth perovskite-type oxides in Ni/MH batteries is described, starting from their crystalline structure and production methods. In each category, a description concerning the latest advances and future research direction is presented. Electrochemical performance of the perovskite-type electrodes is reviewed extensively. In addition, various strategies for enhancing their hydrogen storage capacity as a negative electrode in hydrogen batteries are discussed. Drawbacks and challenges of this technology are also presented.

Electrochemical performance of the rare-earth perovskite-type oxide La0.6Sr0.4Co0.2Fe0.8O3 as negative electrode material for Ni/oxide rechargeable batteries

“…1b) revealed that La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 particles displayed an irregular morphology and were agglomerated with each other. Considering the application, it is always an advantage to use of ultrafine oxides over bulk ones, since the diffusion path of both hydrogen ions and electrons can be shortened using ultrafine particles as demonstrated in previous studies [13,16].…”

“…Interestingly, the obvious expansion of the cell volume in the perovskite-type electrodes is small in comparison to the volumetric expansion experienced by traditional intermetallic alloys (up to 25% volume change) [20]. The change in the cell volume is attributed to the nature of the hydrogen uptake in perovskites [13]. Unlike conventional metal hydride alloys, in a perovskite, the dissociated H 2 O molecule, specifically H ?…”

“…One of the attempts for improving the electrochemical performance of the oxide electrodes was the introduction of dopant elements within the perovskite structure. For example, Deng et al [19] reported a discharge capacity value of around 502 mAh g -1 with a current density of 31.25 mA g -1 at 333 K for the La 1-x Sr x FeO 3 (for x = 0.4) oxide electrode, which is considerably much higher than that reported for the undoped LaFeO 3 and AB 5 alloys [5,6,13]. Another option for improving the electrochemical performance of perovskites was the reduction of the particle size of the powder (from micrometric to nanometric scale) [16].…”

“…Since AB 5 -based alloys present their best performance in a temperature range between 293 and 313 K [12], engineers have proposed various types of materials as alternatives to the intermetallic ones. In this manner, rareearth perovskite-type oxides (REMeO 3 , in which RE = a rare-earth element and Me = a transition metal) have risen as a new kind of material for negative electrodes in Ni/MH batteries [13]. REMeO 3 are known not only for having proton conductivity at high temperatures and under hydrogen atmospheres, but also for their superior hydrogen solubility over other metal oxides.…”

“…Since the metal hydride electrode in Ni/MH batteries can be substituted for the perovskite-type oxide electrode, this new technology has been given the name Ni/oxide battery. Among the different perovskite-type compounds studied as negative electrode materials for Ni/oxide rechargeable batteries [13], LaFeO 3 perovskite-based oxides have shown promising electrochemical performance (capacity values of around 350 mAh g -1 at 333 K) [13,15]. Nevertheless, there are various key points concerning these oxides that are still under investigation.…”