One-pot rapid synthesis of core-shell structured NiO@TiO₂ nanopowders and their excellent electrochemical properties as anode materials for lithium ion batteries

Core-shell structured NiO@TiO₂ nanopowders for application as anode materials for lithium ion batteries are prepared by one-pot flame spray pyrolysis from aqueous spray solution containing Ni and Ti components. A new formation mechanism of the core-shell structured nanopowders in the flame spray pyrolysis is proposed. Composite nanopowders are first formed by surface growth and coagulation from NiO and TiO₂ vapors. A small amount of TiO ₂ in composite powders disturbs the crystallization of TiO ₂. Therefore, the TiO₂ component moves out to the surface of the powders forming an amorphous shell during the formation of single crystalline NiO. The initial discharge and charge capacities of the NiO@TiO ₂ nanopowders at a current density of 300 mA g^-1 are 1302 and 937 mA h g^-1, respectively. The discharge capacities of the pure NiO and NiO@TiO₂ nanopowders after 80 cycles are 542 and 970 mA h g^-1, respectively. The capacity retentions of the pure NiO and NiO@TiO₂ nanopowders after 80 cycles measured after the first cycles are 75 and 108%, respectively.