Enhanced Stability of LiCoO 2 Cathodes in Lithium-ion Batteries Using Surface Modification by Atomic Layer Deposition

Ultrathin atomic layer deposition (ALD) coatings were found to enhance the performance of lithium-ion batteries (LIBs). Previous studies have demonstrated that LiCoO₂ cathode powders coated with metal oxides with thicknesses of ~100-1000 A grown using wet chemical techniques improved LIB performance. In this study, LiCoO₂ powders were coated with conformal Al₂O₃ ALD films with thicknesses of only ~3-4 A established using 2 ALD cycles. The coated LiCoO₂ powders exhibited a capacity retention of 89% after 120 charge-discharge cycles in the 3.3~4.5 V (vs. Li/Li?) range. In contrast, the bare LiCoO₂ powders displayed only a 45% capacity retention. This dramatic improvement may result from the ultrathin Al₂O₃ ALD film acting to minimize Co dissolution or to reduce surface electrolyte reactions.