Electrochemical performance of YMg₂Ni₉ hydrogen storage electrode alloy in-situ coated with Ni₃S₂

The YMg₂Ni₉ hydrogen storage alloy in-situ coated with Ni₃S₂ was successfully prepared by hydrothermal sulfurization treatment and investigated as the anode material in nickel-metal hydride (Ni-MH) batteries for the first time. Owing to the high electronic conductivity and electrocatalytic activity of Ni₃S₂ nanoflake coating, the electrochemical performance of the YMg₂Ni₉ alloy electrode is significantly enhanced. The alloy electrode treated in 0.3 M Na₂S solution exhibits the highest discharge capacity of 230.8 mAh/g and superior cycling stability, maintaining a capacity retention rate of 85.1 % after 100 cycles. The increase in the discharge capacity of the electrode is credited to the Ni₃S₂ coating on the surface of the alloy, which possesses a nanoflake structure, facilitating the surface electrochemical reaction and providing more channels for hydrogen diffusion. In addition, Ni₃S₂ nanoflakes wrapped around the surface of the alloy can stabilize the reaction interface between the alloy and the electrolyte and slow down the alkali erosion, thus improving the cycle life of the electrode. The present study offers beneficial information for investigating a potential anode material for Ni-MH batteries.