Effect of precursor drying temperature on the morphology and electrochemical performance of lithium-rich manganese-based cathode materials

Abstract

With the gradually increasing consumption of coal, oil, and natural gas and the increasing environmental pollution, recyclable secondary energy has become crucial to solving energy and environmental problems. Lithium-ion batteries have penetrated into all aspects of life. Its high energy density, high voltage platform, long life, and environment-friendly characteristics make it widely in-demand. Lithium-ion batteries are used in devices such as mobile phones, tablet computers, and electric vehicles, in which requirements of energy density, rate, and cycle performance are high. The high-capacity lithium-rich material can provide a reversible specific capacity higher than 250 mA·h·g–1 and an energy density of up to 600 W·h·kg–1, making it a positive electrode material. Being a scarce and strategic resource, the price of cobalt has considerably increased. The price fluctuation of cobalt directly affects the cost of the full battery. Drying conditions have a minor effect on most cathode materials and precursors and do not affect the size, morphology, and elemental distribution of their precursors. Thus, virtually no one has explored the effects of such drying conditions. Herein, we studied the drying conditions of cobalt-free lithium-rich cathode materials and explored the influence of drying condition on the morphology and electrochemical performance of cathode materials. Using sodium hydroxide, which is a transition metal sulfate, and ammonia as raw materials, a lithium-rich manganese-based cathode material (Li1.17Ni0.33Mn0.5O2) was prepared via coprecipitation followed by sintering at 900 ℃. The influence of the precursor drying temperature on the macro and micro morphology and electrochemical performance was studied. The results show that the precursor displays a clear macro sintering phenomenon, and particles appear after lithiation at a higher drying temperature. The precursor with the lower drying temperature did not display a macro sintering phenomenon, and no obvious particles appeared after lithiation. After 50 cycles, the remaining capacity of the high drying temperature was only 85%, which is a significant drop. The cathode material with the lower drying temperature did not decrease significantly in capacity after 50 cycles.