Commercial rechargeable lithium-ion batteries (LIBs) use LiCoO2 (LCO) as the cathode, which shows relatively low energy capacity (~140 mAh/g) and suffers poor cycle life performance. To develop next-generation LIBs with high capacity and long cycle life, surface modifications on cathodes have been applied. We start with thin layers of Al2O3 synthesized from sol-gel method to coat on the LCO surfaces and to test the optimal conditions, namely thickness and annealing temperature, for LIB performances in both half-cell and full cell configurations. The best performance (longest cycle life with high retention rate) is found to be 0.5 wt% coated Al2O3 annealed at 600°C. After identifying the best thickness for surface coating, we are moving to test new types of Li+ conducting surface coating, Li2SrSiO4, as predicted by density functional theory on LCO-based (LiNixMnyCo1-x-yO2) cathodes for high-density LIBs with long cycle life.