Hollow spherical 0.5Li2MnO3·0.5LiMn1/3Ni1/3Co1/3O2 prepared by facile molten salt method for enhanced long-cycle and rate capability of lithium-ion batteries

Abstract

Molten salt method has been widely adopted in preparation of a series of battery materials. The formula of the molten salts has a great influence on the morphology and property of the product. In this work, a hollow spherical lithium-rich cathode material (0.5Li2MnO3·0.5LiMn1/3Ni1/3Co1/3O2, LMO) was successfully prepared using a mixed molted salt method. The hollow LMO possesses a higher crystallinity and more Li+ diffusion channels in comparison with the LMO prepared using single salt or no salt, because the mixed salts have a much lower melting point. These structural features endow the hollow LMO with remarkably high initial discharge capacity (280.9 mAh g−1 at 0.1C) and coulombic efficiency, excellent rate performance as well as good cycling stability (500 cycles at 5C). Notably, the hollow LMO exhibits outstanding cycling stability at high temperature (60 °C at 1C over 100 cycles). Further kinetic analyses reveal that the Li+ diffusion coefficient is obviously enhanced, and the charge transfer resistance is reduced by the mixed molten salt method. This work proposes an effective strategy to improve the electrochemical performance of Li-rich cathode materials by regulating the formula of the molten salt method.