Clusters of flower-shaped CuO nanosheets: microstructure and enhanced high-rate dischargeability properties of LaNi3.81Mn0.30Co0.78Al0.11 alloy electrodes

Abstract

Nickel metal hydride (Ni-MH) batteries play an important role in new-energy vehicles; however, the poor high rate dischargeability (HRD) of the negative electrode materials (hydrogen storage alloy) limits its further application in high-power fields. In this work, a facile strategy was applied to improve the HRD performance of AB5-type alloy (LaNi3.81Mn0.30Co0.78Al0.11) by introducing flower-shaped CuO nanosheets to the electrode. Compared with the bare alloy, the modificatory electrode (3 wt.% CuO) shows enhanced HRD performance of increasing from 8.4 to 31.4% at a discharge current density of 1800 mA g−1. Besides, the corresponding capacity retention rate at the 100th cycle (S100) increases from 83.3 to 93.6%. For kinetic property, the exchange current density increases from 144.6 to 267.9 mA g−1 and the hydrogen diffusion coefficient increases from 1.96 × 10−15 to 6.52 × 10−15 cm2 s−1 (3 wt.% CuO), which mean the faster hydrogen diffusion rate. These are contributed to the 3-dimensional clusters of flower-shaped CuO nanosheets seamlessly integrated with hydrogen storage alloy and the formation of Cu particles deposited at the surface of alloy particles during charge/discharge process, decreasing the internal resistance and polarization of the hybrid electrode.