Enhanced electrochemical performance of Li-ion battery cathodes by atomic layer deposition

”Li-ion battery now plays an irreplaceable role in supplying green and convenient energy. In this work, atomic layer deposition (ALD) was used to modify Li-ion battery cathode particles for performance enhancement. An ultrathin and conductive CeO2 ALD film was deposited on Li-rich layered cathode particles, of which the specific capacity and cyclic stability were significantly improved. On the same cathode particles, FeOx ALD and post-annealing resulted in a stable and conductive surface spinel phase to improve the performance. Synergetic TiN coating and Ti doping were performed on a LiFePO4 (LFP) cathode and extended its cycle life. The TiN ALD precursor, TiCl4, reacted with the surface of LFP and formed Ti-doped phase during the ALD process. The modification using FeOx ALD and post-annealing was also carried out on spinel LiMn1.5Ni0.5O4 cathode particles. The parasitic reactions due to high working voltage of this cathode were suppressed by this method, and the intrinsic electronic and ionic conductivities were significantly improved. Moreover, by controlling post-annealing temperature, a porous structure was achieved for the cathode particles, which can further increase the specific capacity and cyclic stability. A synergetic bi-elemental modification was performed on Ni-rich LiNi0.8Mn0.1Co0.1O2 (NMC811) cathode particles using Zr-surface doping, followed by Al2O3 coating. This rational design derived from individual investigation on Al2O3 and ZrO2 modified NMC811, which proved better performance of Al2O3 as a coating material and Zr as a dopant”--Abstract, page iv