Atomic layer deposition of TiO2 shells on CoSe2 nanorods towards enhanced lithium storage performance

Surface modification via atomic layer deposition (ALD) of metal oxides ( ex. , TiO 2 ) has been suggested as an effective strategy to enhance the electrochemical performance of high-specific-capacity electrode materials. Herein, we study the lithium storage behavior of TiO 2 coated CoSe 2 nanorods (TiO 2 @CoSe 2 ), in which a thin layer of TiO 2 shell is deposited via a conventional ALD method. The effects of the TiO 2 deposition on the structural and electrochemical characteristics of the CoSe 2 nanorods are systematically investigated. When applied as anodes for LIBs , the TiO 2 @CoSe 2 electrode displays much enhanced lithium storage performance including higher specific capacity, better cycle stability and rate capability, delivering a discharge capacity of 999.2 mA h/g after 300 cycles at 200 mA/g and an exceptional capacity of 723.7 mA h/g after 430 cycles even at high current density of 500 mA/g, which is much higher than that of the bare CoSe 2 electrode (only 145.4 mA h/g after 220 cycles at 200 mA/g).