Effect of reduced graphene oxide-supported copper addition on electrochemical properties of La0.7Mg0.3Ni2.8Co0.5 electrodes

Abstract

The reduced graphene oxide-supported copper (Cu@rGO) nanocomposite was introduced to improve the electrochemical properties of La0.7Mg0.3Ni2.8Co0.5 alloy electrodes. Experimental results show that adding Cu@rGO nanocomposite with mass fractions of x wt% (x = 0, 3, 6 and 9) to the alloy electrodes provides electrodes with maximum discharge capacities of 368.9 mAh/g (x = 0), 373.2 mAh/g (x = 3), 407.3 mAh/g (x = 6) and 398.6 mAh/g (x = 9), and high-rate dischargeabilities at a discharge current density of 1200 mA/g of 40.5% (x = 0), 64.0% (x = 3), 82.0% (x = 6) and 76.0% (x = 9). The addition of Cu@rGO nanocomposite also provides alloy electrodes with hydrogen diffusion coefficients of 3.7 × 10−10 cm2/s (x = 0), 4.1 × 10−10 cm2/s (x = 3), 4.2 × 10−10 cm2/s (x = 6) and 4.0 × 10−10 cm2/s (x = 9). Clearly, the addition of 6 wt%Cu@rGO nanocomposite not only increases the electrochemical capacity of La0.7Mg0.3Ni2.8Co0.5 alloy electrodes, but also improves their electrochemical kinetic properties.