Manipulating electrolyte concentration for metal hydride electrode at ultra-low temperature

Metal hydride electrode has been widely used in alkaline aqueous battery due to their merits of good comprehensive performance and high safety. However, their further development is hindered by ultra-low-temperature performance. We prepare an electrode and discuss the effect of KOH electrolyte concentration for the ultra-low-temperature performance of the electrode. The C max of the electrode increases from 163.7 mAh g −1 (5 M) to 322.2 mAh g −1 (9 M) at − 40 °C due to the R ct decreasing obviously. The R ct decreases, and I 0 and D increase with KOH concentration increasing from 5 to 9 M, and the maximum value of HRD 150 obtains 82.60% (9 M) at − 40 °C. Thus, the transfer resistance and hydrogen diffusion coefficient affect simultaneously the HRD performance. Moreover, the cycle stability of the metal hydride electrode will be improved significantly at ultra-low temperature because the I corr decreases sharply. Therefore, the outstanding ultra-low-temperature performance demonstrates the electrode in 9 M KOH electrolyte for excellent ultra-low-temperature aqueous Ni-MH battery. Graphical abstract