采用液相共沉淀法和固相烧结法分别制备镍钴锰复合氢氧化物(Ni0.5Co0.2Mn0.3(OH)2)和LiNi0.5Co0.2Mn0.3O2正极材料.通过X射线衍射和电化学性能测试对所得样品的结构及电化学性能进行了表征.结果表明:LiNi0.5Co0.2Mn0.3O2具有很好的α-NaFeO2层状结构,以20 mA/g的电流密度在2.5~4.3 V的电压区间充放电时,最高首次放电比容量达175 mA·h/g,首次库伦效率在89%~90%之间.当首次放电比容量为160~170 mA·h/g时,30循环未见容量衰减.锂含量对其电化学性能影响的结果表明:锂含量(n(Li)/n(Ni+Co+Mn))在1.03~1.09的范围内,随着锂含量的增加,放电比容量略有减小,但循环性能、中值电压以及平台性能都得到提高;当锂含量超过1.09时,循环性能、中值电压以及平台性能开始降低.
@@@@The nickel and cobalt manganese composite hydroxide(Ni0.5Co0.2Mn0.3(OH)2) and LiNi0.5Co0.2Mn0.3O2 cathode materials were prepared by the solid state sintering synthesis and liquid phase coprecipitation. The structure and electrochemical performance were characterized by X-ray diffractometry and electrochemical properties test. The results show that the cathode material LiNi0.5Co0.2Mn0.3O2 hasα-NaFeO2 structure. The highest initial discharge capacity is 175 mA·h/g at current density of 20 mA·h/g in 2.7?4.3 V (vs Li/Li+), while the coulombic efficiency is 89%?90%. When the initial discharge capacity is at the range of 160?170, the capacity does not fade after 30 cycles. When n(Li)/n(Ni+Co+Mn) are 1.03?1.09, the discharge specific capacity decreases little with molar ratio of Li to M increasing. When molar ratio of Li to M is bigger than 1.09, the cycling performance, mean voltage and discharge plateau begin to fade.
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