High-stability 5 V spinel LiNi0.5Mn1.5O4 sputtered thin film electrodes by modifying with aluminium oxide

Abstract Aluminium oxide (Al 2 O 3 )-modified LiNi 0.5 Mn 1.5 O 4 (LNMO) thin-film electrodes were prepared by pulsed laser deposition and effects of surface modification on interfacial reactions of LNMO were studied. The modification by Al 2 O 3 was carried out successively after the deposition of LNMO thin-film. Field-emission Scanning Electron Microscope results show that Al 2 O 3 disperses uniformly in nano-scale on the film electrodes. Charge/discharge behavior of the batteries under a high cutoff voltage of 4.9 V vs. Li is highly improved by using Al 2 O 3 modification, especially at elevated temperature. The electrochemical properties of LNMO thin-film electrodes are also affected by the thickness of coating. It is found that 20 nm thick Al 2 O 3 coating layer improves thermal stability most obviously among them. At 55 °C, 84.1% of its initial capacity at 1C-rate can be retained after 100 cycles, and as the rate increases from 0.2 to 10 C the reversible capacity can still maintain 80.7mAhg −1 , which are greatly improved compared to pristine, 6 and 40 nm thick Al 2 O 3 modified samples.