LiNixCoyMn1-x-yO2 Cathode Material Synthesized through Construction of E-pH Diagram and Its Electrochemical Performance

LI Ling, LI Yun-Jiao, XU Bin, LU Wei-Sheng, SU Qian-Ye, CHEN Yong-Xiang, LI Lin
2018 Journal of Inorganic Materials  
摘 要: 通过热力学计算获得了 Li-Ni-Co-Mn-H 2 O 系中各物质的热力学数据, 从而绘制了 25℃和 200℃、离子活度 为 1.00 下的 Li-Ni-Co-Mn-H 2 O 系电位-pH 图。 热力学分析结果表明: 温度为 25℃时, 在 pH 3~13 范围内, 水溶液中 未出现 LiNi x Co y Mn 1-x-y O 2 稳定区域; 随着温度升高, Li-Ni-Co-Mn-H 2 O 系中各物质的稳定区域向低 pH 和低电位方向 移动。在温度为 200℃, pH 为 9.7~13.0 的水溶液中出现了 LiNi x Co y Mn 1-x-y O 2 稳定区域。这说明在一定温度下, 水溶液 中合成 LiNi x Co y Mn 1-x-y O 2 是可能的, 且提高温度有利于合成反应进行。 进一步通过实验验证, 以(Ni 0.5 Co 0.2 Mn 0.3 ) (OH) 2 前驱体和 LiOH·H 2 O 为原料, 在水溶液中成功获得具有 α-NaFeO 2 层状结构的锂镍钴锰四元前驱体, 经过热处理后 得到循环稳定性良好的 LiNi 0.5 Co 0.2
more » ... 良好的 LiNi 0.5 Co 0.2 Mn 0.3 ; 锂离子电池; 正极材料 中图分类号: TM912 文献标识码: A Abstract: The thermodynamic data of various species in Li-Ni-Co-Mn-H 2 O system is obtained by thermodynamics calculation, and E-pH diagrams for Li-Ni-Co-Mn-H 2 O system with activity 1.00 at 25℃ and 200℃ were constructed. From E-pH diagrams, it shows that there is no predominant region of the LiNi x Co y Mn 1-x-y O 2 composite oxide in pH range of 3~13 at 25℃. However, the stability region of various species expands towards the low pH and low potential zones as the temperature increases. When pH is between 9.7~13.0 at 200℃, synthesis of LiNi x-Co y Mn 1-x-y O 2 via aqueous process is thermodynamically possible, and high temperature is favorable. Experimental results showed that the composite precursor (LNCM) with α-NaFeO 2 structure was successfully prepared in aqueous solution by using (Ni 0.5 Co 0.2 Mn 0.3 )(OH) 2 as precursor and LiOH·H 2 O as raw material. LiNi 0.5 Co 0.2 Mn 0.3 O 2 cathode materials were then obtained by post heat treatment and following tests exhibited excellent cycling performance. These experimental results are in consistent with the information given in E-pH diagram of the Li-Ni-Co-Mn-H 2 O system, and the as-prepared LiNi 0.5 Co 0.2 Mn 0.3 O 2 cathode materials show excellent cycling performance.
doi:10.15541/jim20170192 fatcat:s7yscf75rnb6nk4kjuusmfhjxy