Improved electrochemical performances of nanocrystalline Li[Li0.2Mn0.54Ni0.13Co0.13]O2 cathode material for Li-ion batteries

Layered Li[Li0.2Co0.13Ni0.13Mn0.54]O-2 nanoparticles were synthesized by a simple polymer-pyrolysis method and then coated with 3 wt% Al2O3 to form a similar to 4 nm thick protective skin. The Al2O3-coated Li[Li0.2Co0.13Ni0.13Mn0.54]O-2 electrode demonstrates a high initial coulombic efficiency of 96.1%, a large reversible capacity of similar to 311 mAh g(-1), and a good cyclability with 83.8% capacity retention after 70 cycles. Particularly, this material can deliver a quite high capacity of similar to 239 mAh g(-1) at a high rate of 400 mA g(-1). This superior electrochemical performance results from the well-crystallized nanocores and effective surface modification of the material. The former provides a short diffusion path and fast transport channels for lithium ion insertion/extraction reactions and the latter restrains the elimination of oxide ion vacancies and metal ion rearrangement during charge-discharge cycling. Due to their simplicity and applicability, the synthetic method along with the surface modification technique is easily adopted to make high performance xLi(2)MnO(3)center dot(1 - x)LiMO2 materials for practical battery applications.