前驱体烘干温度对富锂锰基正极材料形貌和电化学性能的影响

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

  • 摘要: 以过渡金属硫酸盐、氢氧化钠、氨水为原料,通过连续共沉淀–高温固相法制备了富锂锰基正极材料Li1.17Ni0.33Mn0.5O2。对其进行了包括微观形貌、宏观形貌、晶体结构、电化学性能等方面的表征,研究了前驱体烘干温度对于粒度较小前驱体的宏观形貌及锂化后正极材料的微观形貌和电化学性能的影响。结果表明,烘干温度较高的前驱体在烘干后出现了明显了宏观烧结现象,锂化并涂布后出现了明显的颗粒;烘干温度较低的前驱体在烘干后并未出现宏观烧结现象,锂化并涂布后未出现明显的颗粒。在电化学性能方面,前驱体烘干温度较高的正极材料在经历50个循环后,可逆比容量只剩下85%,下降比较明显;前驱体烘干温度较低的正极材料在经历了50个循环后,可逆比容量未出现明显下降。

     

    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.

     

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