Effect of passivating Al2O3 thin films on MnO2/carbon nanotube composite lithium-ion battery anodes

Abstract

MnO2/carbon nanotube composite electrodes for Li-ion battery application were directly coated with ultrathin thicknesses of aluminum oxide film by atomic layer deposition (ALD). The non-reactive Al2O3 layer not only provides a stable film to protect the manganese oxide and carbon nanotubes from undesirable reaction with the electrolyte but also restrains the volume change strain of manganese oxide during cycling. The first cycle Coulombic efficiency of coated samples was increased to different extents depending on the coating thickness. In the following cycles, the coated electrodes denote high specific capacity, good capacity retention ability, and perfect rate charge/discharge performance.