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mno2 摘 要锂离子电池已经成为现代电子设备和移动终端的能源核心，在全球能源消费市场中所占的比率不断增长。但是，随着锂离子电池在电动汽车、智能移动设备和大功率电器、电网储能领域的发展，人们对商业化的锂离子电池在比容量和循环稳定性、高倍率性能方面提出了更高的要求。其中，过渡金属氧化物负极材料是一种新的高比容量材料，由于锂转化反应加快，同时也有良好的储锂性能，经过材料优化和结构升级，可尝试用作锂离子电池的负极材料。
MnO2具有较高的理论比容量（1233 mAh·g-1），但是在放电过程中容易粉化，而TiO2具有充放电循环稳定性好的优点。
因此，我们使用MnO2/TiO2作为锂离子电池的负极材料，并通过其电化学测试研究了储锂性能。
X射线衍射（XRD）和傅里叶变换红外光谱（FT-IR）和元素分析结果表明所制备的材料为MnO2/TiO2的复合材料。电化学测试结果表明，在100mA·g-1的电流密度下，TiO2的首次放电比容量为106.7 mAh·g-1，而MnO2/TiO2复合材料的首次放电比容量提高到了740.7 mAh·g-1；100次循环后MnO2/TiO2复合材料的放电比容量仅为38.7 mAh·g-1，比纯TiO2的48.1 mAh·g-1还低，说明在充放电过程中MnO2还是发生了明显的粉化，二氧化钛的结构稳定作用不太明显。倍率性能结果表示，1000 mA·g-1的高电流密度下可以获得的放电容量是在100 mA·g-1的低电流密度下放电容量的5.2%，表明制备的MnO2/TiO2 材料结构在大电流密度下结构破坏更加迅速。
MnO2/TiO2的复合材料能够提高其储锂比容量，但是循环稳定性和倍率性能并没有得到提升，需要进一步研究。
关键词：锂离子电池；负极材料；MnO2/TiO2
Abstract
Lithium-ion batteries have become the core of modern electronic equipment and mobile terminals, and the market share in the global energy consumption is growing. However, with the development of lithium-ion batteries in the field of electric vehicles, intelligent mobile devices, high-power electrical appliances and power grid energy storage, the higher specific capacity and cycle stability and rate performance are requested. Among them, the transition metal oxide anode material is a new high specific capacity material, because of the rapid lithium conversion reaction and good lithium storage performance. Through material optimization and structural upgrading, the transition metal oxide can be used as a lithium ion battery anode material.
MnO2 has a high theoretical specific capacity (1233 mAh/g), but it is easy to pulverize during the charge/discharge process. However, TiO2 has the advantages of good stability of charge and discharge cycle. Therefore, we use MnO2/TiO2 as the anode material of lithium ion battery, and the electrochemical performance of lithium storage has been studied.
X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and elemental analysis show that the prepared materials were MnO2/TiO2 composites. The electrochemical test results show that the first discharge capacity of TiO2 is 106.7 mAh/g at the current density of 100 mA/g, and the first discharge capacity of MnO2/TiO2 composites is increased to 740.7 mAh/g. The discharge capacity of MnO2/TiO2 composite is only 38.7 mAh/g after 100 cycles, which is lower than that of pure TiO2 (48.1 mAh/g). The results indicate that MnO2 is obviously pulverized during charging and discharging process and the structural stability effect of titanium dioxide is not obvious. The results of rate performance show that the discharge capacity at 1000 mA/g is 5.2% of that under the low current density of 100 mA/g, indicating that the prepared MnO2/TiO2 material has a obvious structure damage at high current density.
MnO2/TiO2 composite material can improve the specific capacity of the lithium storage capacity, but the cycle stability and magnification performance have not been improved, which need further study.
Key words：Lithium-ion batteries；Anode material；MnO2/TiO2
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