Ni and Co doped yolk-shell type Fe₂O₃ hollow microspheres as anode materials for lithium-ion batteries

Ni and Co doped Fe₂O₃ hollow microspheres of yolk-shell type were designed and synthesized by using resin (RF-COOH) microspheres as hard template and subsequent calcination. Specific morphologies (walnut-like, jingle-bell-like and ball-like) and compositions of Fe₂O₃ with different amounts of Ni and Co doping were obtained by tuning metal precursor concentration to optimize their performance in lithium-ion battery application. When Ni and Co doped Fe₂O₃ hollow microspheres were used as anode materials for lithium-ion batteries, jingle-bell-like and ball-like morphologies showed better electrochemical performance with specific capacities of 415.7 and 414.1 mA h/g, respectively up to 200 cycles due to their stable construction with hollow cavity, porous shell and Ni and Co dopants. However, the specific capacity of Ni and Co doped Fe₂O₃@TiO₂ hollow microspheres increased to 562 mA h/g. This work showed a new avenue for designing and fabricating yolk-shell hollow structures with specific morphologies and compositions in order to optimize their specific capacity for use in lithium-ion batteries.