Synthesis of porous peanut-like LiNi0.5Mn1.5O4 cathode materials through an ethylene glycol-assisted hydrothermal method using urea as a precipitant
Synthesis of porous peanut-like LiNi0.5Mn1.5O4 cathode materials through an ethylene glycol-assisted hydrothermal method using urea as a precipitant
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DOI：
10.1039/c5ta05550d
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发表时间：
2015-09
影响因子：
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通讯作者：
Li Wang;G. Liu;Wei Wu;Dan Chen;Guangchuan Liang
中科院分区：
文献类型：
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作者：
Li Wang;G. Liu;Wei Wu;Dan Chen;Guangchuan Liang
以尿素为沉淀剂，采用乙二醇辅助水热法合成了具有花生状形貌和多孔结构的高压尖晶石LiNi 0. 5 Mn 1. 5 O 4。为了比较，LiNi0.5Mn1.5O4样品也在不存在乙二醇（EG）的水溶液中合成。采用XRD、SEM、TEM、FT-IR、CV、EIS和恒流充放电等测试手段对材料进行了表征。在水热过程中EG的存在改善了分散性并减小了最终LiNi0.5Mn1.5O4产物的粒度，从而导致其更好的倍率性能，其在10 C倍率下的放电容量可高达121.4 mA h g−1。另一方面，EG的存在使反应物混合更均匀，结晶度更高，杂质和Mn 3+含量更低，有利于循环性能的提高。此外，LiNi0.5Mn1.5O4材料的多孔结构可以有效地减轻由重复Li+插入/拔出过程引起的体积变化，这也有利于循环稳定性。通过EG辅助水热法合成的LiNi 0.5Mn 1.5O4正极材料在1C倍率下循环100次后显示出96.4%的容量留存率。此外，还提出了花生状形貌的Ni0.25Mn0.75CO3前驱体的可能形成机理。
The high voltage spinel LiNi0.5Mn1.5O4 with a peanut-like morphology and porous structure was synthesized by an ethylene glycol-assisted hydrothermal method using urea as a precipitant followed by high-temperature calcination. For comparison, the LiNi0.5Mn1.5O4 sample was also synthesized in the aqueous solution in the absence of ethylene glycol (EG). The as-prepared materials were characterized by XRD, SEM, TEM, FT-IR, CV, EIS and galvanostatic charge/discharge tests. The presence of EG in the hydrothermal process improves the dispersity and decreases the particle size of the final LiNi0.5Mn1.5O4 product, thus leading to its better rate capability, whose discharge capacity at a 10C rate could reach as high as 121.4 mA h g−1. On the other hand, the presence of EG in the hydrothermal process could make the reagents mix more homogeneously, thus leading to higher crystallinity, lower impurity and Mn3+ contents, which are advantageous to the cycling performance. Furthermore, the porous structure of the LiNi0.5Mn1.5O4 material could effectively mitigate the volume change caused by the repeated Li+ insertion/extraction process, which is also conducive to the cycling stability. The LiNi0.5Mn1.5O4 cathode material synthesized by the EG-assisted hydrothermal process shows a capacity retention rate of 96.4% after 100 cycles at a 1C rate. Additionally, a possible formation mechanism for the Ni0.25Mn0.75CO3 precursor with a peanut-like morphology was also proposed.