Ultrathin Surface Modification By Atomic Layer Deposition on High Voltage Cathode LiNi0.5Mn1.5O4 for Lithium Ion Batteries

Monday, May 12, 2014: 14:20
Bonnet Creek Ballroom I, Lobby Level (Hilton Orlando Bonnet Creek)
X. Fang, M. Ge, J. Rong, Y. Che, N. Aroonyadet, X. Wang, Y. Liu, A. Zhang, and C. Zhou (USC)
Atomic layer deposition (ALD) has been employed to modify the surface of high voltage cathode LiNi0.5Mn1.5O4 by coating ultrathin Al2O3 layer on the electrodes. The ultrathin layer of Al2O3 can suppress the undesirable reactions during cycling, while maintaining the electron and ion conductivity of the electrode. The ALD Al2O3 coated LiNi0.5Mn1.5O4 showed remarkable improvement over bare LiNi0.5Mn1.5O4. After 200 cycles, the ALD Al2O3 coated LiNi0.5Mn1.5O4 showed 91% capacity retention when the bare LiNi0.5Mn1.5O4 can only maintain 75% in the same testing condition. In addition, the ALD coated LiNi0.5Mn1.5O4 maintained 63% capacity retention after as long as 900 cycles. At an elevated temperature of 55 ºC, the ALD Al2O3 coated LiNi0.5Mn1.5O4 still delivered 116 mAh/g at the 100th cycle, in comparison, the capacity for bare LiNi0.5Mn1.5O4 decreased to 98 mAh/g. According to the results from charge/discharge test and AC impedance test, the improvement is ascribed to the reduced overpotental and Li ion surface diffusion impedance. The promising results demonstrate the potential of developing high energy and long life lithium ion batteries with highly scalable LiNi0.5Mn1.5O4 preparation and broadly applicable ALD process.