溶液处理富锂锰基固溶体Li_1.2Mn_0.54Ni_0.13Co_0.13O_2

Surface modification by chemical leaching of lithium-manganese-rich layered oxides Li_1.2Mn_0.54Ni_0.13Co_0.13O_2

针对Li1.2Mn0.54Ni0.13Co0.13O2材料的首次效率过低和倍率性能差的缺陷,系统研究了中性去离子水、弱酸性的硫酸铵和强酸性的磷酸3种不同pH值的溶液处理对Li[Li0.2-Mn0.54Ni0.13Co0.13]O2综合性能的影响.ICP结果表明预处理液的pH值对Li的析出量有显著影响;XRD结果显示处理对材料的体相结构有影响;XPS证实处理对材料表面过渡金属元素的价态没有影响.充放电测试表明,硫酸铵处理后的样品具有最优的电化学性能,首次效率由64.6%提高到85.4%,1 C放电容量从149.5 mA h g?1提高到183.7 mA h g?1,中值电压呈缓和下降趋势.

Focusing on its low initial columbic efficiency and poor rate capability, Li[Li0.2Mn0.54Ni0.13Co0.13]O2 was chemically pretreated with various solutions with different pH values, including deionized water, （NHa）2SO4 and H3PO4. ICP analysis states pH value has significant effect on the amount of leached Li element. XRD results prove the bulk structure of the material is changed after treatment. XPS results show the valence states of the transition elements remain unchanged after treatment. Electrochemical test shows the sample treated with （NH4）2SO4 possesses the optimal comprehensive performance. The initial columbic efficiency is enhanced from 64.6% to 85.4% and the discharge capacity at 1 C increased from 149.5 mA h g-1 to 183.7 mA h g-1. The improvement is attributed to the pre-leaching of Li and formation of a new spinel structure.