Improved Electrochemical Performance of LiMn2O4 via Ni and Co Gradient Doping
Improved Electrochemical Performance of LiMn2O4 via Ni and Co Gradient Doping
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通过 Ni 和 Co 梯度掺杂改善 LiMn2O4 的电化学性能
DOI：
10.1166/sam.2018.3425
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发表时间：
2018-12
影响因子：
0.9
通讯作者：
Jianbing Jiang
中科院分区：
文献类型：
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作者：
Wei Li;Haojie Deng;Jianbing Jiang
采用共沉淀法在Mn 3 O 4（GM）中实现了Ni和Co的梯度掺杂。以梯度掺杂锂离子电池（GM）和Li_2CO_3为原料，合成了梯度掺杂LGM。采用X射线衍射（XRD）、扫描电子显微镜（SEM）和X射线光电子能谱（XPS）研究了梯度掺杂元素对LGM的结构、形貌和价态的影响。结果表明，梯度掺杂后LGM的结构与JCPDS卡号35-0782的LiMn 2 O 4几乎相同。扫描电镜观察表明，所制备的样品均为球形颗粒。充放电测试结果表明，梯度掺杂提高了材料的循环性能和容量。当掺杂量为Co = Ni = 1%时，LGM在室温下3 ~ 4.3V、148 mA/g放电电流下的首次放电容量达到119.8mAh/g。循环200次后，容量仍保持在115.8mAh/g。交流阻抗谱（EIS）结果表明，LGM的R Ω值随掺杂量的增加而增大。XPS曲线显示Ni和Co的价态分别为+2和+3。
Ni and Co were successfully gradient doped in Mn3O4 (GM) via co-precipitation method. Then, gradient doped lithium manganate (LGM) was synthesized with GM and Li2CO3 as raw materials. To investigate the influence of gradient doping elements on the structure, morphology and the value state of LGM, X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscope (XPS) were employed. The results demonstrated that the structure of LGM after gradient doping was almost the same as LiMn2O4 with JCPDS Card No. 35-0782. The SEM figure indicated that the morphology of all prepared samples was spherical grain. From the results of charge–discharge test, it demonstrated that both of the cycle performance and capacity were improved through gradient doping. When the doping content was Co = Ni = 1%, the initial discharge capacity of LGM reached 119.8 mAh/g at discharge current of 148 mA/g between 3 and 4.3 V at room temperature. The capacity still retained 115.8 mAh/g after 200 cycles. The results of impedance spectroscopy (EIS) indicated the R Ω value of LGM increased with the augment of doping content. XPS curves revealed the valance of Ni and Co were +2 and +3, respectively.