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., TiO2) 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 TiO2 coated CoSe2 nanorods (TiO2@CoSe2), in which a thin layer of TiO2 shell is deposited via a conventional ALD method. The effects of the TiO2 deposition on the structural and electrochemical characteristics of the CoSe2 nanorods are systematically investigated. When applied as anodes for LIBs, the TiO2@CoSe2 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 CoSe2 electrode (only 145.4 mA h/g after 220 cycles at 200 mA/g). Atomic layer deposition (ALD) of TiO2 shells on CoSe2 nanorods (TiO2@CoSe2) allows much enhanced lithium storage performance including higher specific capacity, better cycling stability and rate capability, when used as an anode material for lithium ion batteries, owing to the efficient buffering effect on the electrode pulverization upon cycling. [Display omitted] •CoSe2 nanorods were successfully prepared by a facile hydrothermal method.•TiO2 shells with controlled thickness were coated on the CoSe2 nanorods via a facile atomic layer depositon method.•TiO2@CoSe2 demonstrated much enhanced lithium storage performance as anode for lithium ion batteries.•Deposition of TiO2 shells greatly improved the structure stability of CoSe2 electrode upon lithiation/delithiation cycling.