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

Abstract

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\xa0=\xa00, 3, 6 and 9) to the alloy electrodes provides electrodes with maximum discharge capacities of 368.9\xa0mAh/g (x\xa0=\xa00), 373.2\xa0mAh/g (x\xa0=\xa03), 407.3\xa0mAh/g (x\xa0=\xa06) and 398.6\xa0mAh/g (x\xa0=\xa09), and high-rate dischargeabilities at a discharge current density of 1200\xa0mA/g of 40.5% (x\xa0=\xa00), 64.0% (x\xa0=\xa03), 82.0% (x\xa0=\xa06) and 76.0% (x\xa0=\xa09). The addition of Cu@rGO nanocomposite also provides alloy electrodes with hydrogen diffusion coefficients of 3.7\xa0×\xa010−10\xa0cm2/s (x\xa0=\xa00), 4.1\xa0×\xa010−10\xa0cm2/s (x\xa0=\xa03), 4.2\xa0×\xa010−10\xa0cm2/s (x\xa0=\xa06) and 4.0\xa0×\xa010−10\xa0cm2/s (x\xa0=\xa09). Clearly, the addition of 6\xa0wt%Cu@rGO nanocomposite not only increases the electrochemical capacity of La0.7Mg0.3Ni2.8Co0.5 alloy electrodes, but also improves their electrochemical kinetic properties.