Improving the Electrochemical Properties of High-Voltage LiNi0.5Mn1.5O4 for Li-Ion Battery by Modified Current Collectors

Abstract

The stability of current collector in high voltage LiNi0.5Mn1.5O4 batteries and the rate performance and cyclic stability of LiNi0.5Mn1.5O4 electrodes using three current collectors were investigated, including an Al foil, an etched Al foil (E-Al), and a carbon-coated Al foil (C-Al). The oxidation stability of current collector at high voltage is significantly improved by carbon coating on the Al foil, which can make a good contact between the current collector and active layer. The surface structure and composition of the current collectors strongly affect the rate capability and cyclic performance of LiNi0.5Mn1.5O4 electrodes. Interestedly, using the C-Al current collector not only remarkably increases the rate capability with the capacity of 78 mAh g−1 and the average discharge voltage of 4.1 V at 40 C-rate, but also greatly enhances its cyclic stability at 55°C. Furthermore, the formation of a thin and uniform surface film is observed on the cycled LiNi0.5Mn1.5O4 electrode using the C-Al current collector, which can be attributed to reducing the electrode polarization and suppressing the electrolyte decomposition, leading to good capacity retention. In brief, the carbon-coated Al foil can be applicable to the high voltage LiNi0.5Mn1.5O4 material of Li-ion battery.