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锂离子电池高电压正极材料镍锰酸锂的制备及电化学性能研究
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摘要
微乳液法是锂离子电池正极材料的一种新型制备方法,通过将反应物原料配制成微乳液,然后加入沉淀剂H_2C_2O_4溶液,使反应在其水核内部比较温和的发生发生,有效地控制产物的尺寸和形貌,制备得到形貌均匀的径向纳米尺寸产物LiNi_(0.5)Mn_(1.5)O_4正极材料。测试产物的电化学性能,结果显示:在0.5、10和20 C倍率下,首次放电比容量分别为130.03、113.6和101.4 mA h g~(-1),经过100次循环后分别保持127.9、102.2和85.1 mA h g~(-1)的放电比容量,其容量保持率可达98.4、89.9和83.9%。说明这种形貌均匀的径向纳米尺寸能够极大地缩短电极反应中电子和锂离子的传输距离,并且其较大的比表面积可以为电极材料和电解液提供更大的接触面积,从而显著的提高锂离子脱出和嵌入的速度,使电极材料表现出优异的电化学性能。
Microemulsion method is a new preparation method for lithium ion battery cathode materials.We adopt microemulsion to make the reaction happen in the water nuclei by manufacturing the reactants as microemulsion,and to effectively control the size of the product as far as possible.We found that reaction can take place more moderate and generate nanorod LiNi_(0.5)Mn_(1.5)O_4 cathode material when using H_2C_2O_4 solution as precipitation agent.The products display discharge capacities of 130.03、113.6 and 101.4 mA h g~(-1) at 0.5、10 and 20 C rate,respectively,and demonstrate good cycling stability for capacity retention of 98.4%、89.9% and 83.9% after 100 cycles.The excellent rate performances are mainly attributed to the nanoscale size,which can greatly shorten lithium diffusion lengths and provide appropriate contact area between active materials and electrolyte.
引文
[1]邓海福,聂平,申来法,等.锂离子电池用高电位正极材料LiN i0.5Mn1.5O4[J].化学进展,2014,26(6):939-949.

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