Strategy of manipulating La/Ce ratio to develop metal hydride electrode with excellent capacity even at −40 °C

• Published in: Journal of power sources 2022-09, Vol.543, p.231817, Article 231817
• Main Authors: Tan, Cheng, Jiang, Wenbin, Cui, Jie, Min, De, Liao, Canhui, Ouyang, Liuzhang, Zhu, Min
• Format: Article
• Language: English
• Subjects: La/ce ratio; Metal hydride electrode; Ni/MH battery; Ultra-low-temperature performance
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2022.231817

Metal hydride electrodes have been widely used in Ni/MH batteries, but their low-temperature discharge (LTD) performance restricts practical application. Herein, we propose a facile strategy for tuning the La/Ce ratio to prepare metal hydride electrodes for ultra-low-temperature Ni/MH batteries. The enthalpy shifts in the positive direction with a decrease in the La/Ce ratio and the thermodynamic stability decreases. Moreover, the resultant enhanced charge transfer and proton diffusion endows the electrode with impressive kinetics at −40 °C. One novel candidate, namely, La0.55Ce0.37M electrode presents the highest reported capacity of 317.3 mAh g−1 (0.2C) and the highest discharge specific capacity of 27.2 mAh g−1 (1C) even at −40 °C. A commercial-grade AAA nickel-metal hydride battery concomitantly presents the specific capacity of 71 and 456 mAh at a large current of 1000 mA at −40 and −20 °C, respectively. The excellent LTD performance indicates the suitability of this strategy for developing advanced ultra-low-temperature Ni/MH batteries. [Display omitted] •The La/Ce ratio strategy promotes the thermodynamic and kinetic properties.•The La0.55Ce0.37M electrode has the capacity of 317.3 mAh g−1 (0.2C) at −40 °C.•A commercial-grade AAA battery presents the capacity of 71 mAh (2C) at −40 °C.