Gradient V2O5 surface-coated LiMn2O4 cathode towards enhanced performance in Li-ion battery applications

The spine! LiMn2O4 was recognized as an appealing candidate cathode material for high rate Li-ion battery, but it suffers from severe capacity fading, especially at a high temperature. In order to solve this problem, we prepared V2O5 coated LiMn2O4 (LiMn2O4@V2O5) samples in this work and its structure and morphology were characterized by powder X-ray diffraction, scanning electron microscope, and transmission electron microscope. The LiMn2O4@V2O5 material delivers an excellent cycling ability and rate capability in lithium batteries, while sustaining a capacity of 75.5 mAh g(-1) after 200 cycles at 2 C with a high operating temperature (328 K). This performance are much better than that of LiMn2O4 (35.4 mAh g(-1)) without V2O5 coating, the capacity of which faded seriously. These results indicated that the surface modification of V2O5, which possess a relative lower operating potential (<= 3.7V, LixV2-x/5O5) compare to the LiMn2O4 (similar to 3.9 and 4.1 V), can improve the electrochemical properties of LiMn2O4 by endowing a fast lithium diffusion and reasonable electronic conductivity which facilitates the transformation of the electrons and ions. In addition, the acidic and isolated protective layer of V2O5 can work as a HF inhibitor and/or HF scavenger and suppress the dissolution of manganese into electrolyte. Thus, we believe that such a LiMn2O4@V2O5 composite can be an economical and viable candidate cathode material for Li-ion batteries. (C) 2014 Elsevier Ltd. All rights reserved.