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Yang Yu, Jianling Li, Guimei Han, Zhe Yang, Jianjian Zhong, and Feiyu Kang, Optimize two-phase distribution of lithium-rich materials to stabilize structure and suppress voltage attenuation, Int. J. Miner. Metall. Mater., 29(2022), No. 12, pp.2201-2211. https://dx.doi.org/10.1007/s12613-021-2362-7
Yang Yu, Jianling Li, Guimei Han, Zhe Yang, Jianjian Zhong, and Feiyu Kang, Optimize two-phase distribution of lithium-rich materials to stabilize structure and suppress voltage attenuation, Int. J. Miner. Metall. Mater., 29(2022), No. 12, pp.2201-2211. https://dx.doi.org/10.1007/s12613-021-2362-7
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优化富锂材料亮相分布提高结构稳定性及抑制电压衰减

摘要: 富锂材料虽然具有超高的比容量,但由于氧的氧化还原不完全可逆,因此会出现电压衰减和结构不稳定的现象。本文首次采用分布共沉淀的方法以通过控制过渡金属元素的分布来实现对两相分布的调控。经过检测发现成功的增加了颗粒内部中LiMO2(M = Ni、Co、Mn)相的含量以及颗粒表面Li2MnO3相的含量,并在表面形成了Li4Mn5O12尖晶石相。这使得材料表现出优异的电化学性能:LR(原始)在 1 C 500 圈循环后的放电比容量为 72.7 mAh⋅g−1,而GR(改性样品)的放电比容量仍为 137.5 mAh⋅g−1。在1 C循环220圈后,GR 的放电中压仍然保持在3 V以上。因此,通过调节两相的局部状态可以有效地稳定材料结构和抑制电压衰减。

 

Optimize two-phase distribution of lithium-rich materials to stabilize structure and suppress voltage attenuation

Abstract: Lithium-rich materials possess the ultra-high specific capacity, but the redox of oxygen is not completely reversible, resulting in voltage attenuation and structural instability. A stepwise co-precipitation method is used for the first time in this paper to achieve the control of the two-phase distribution through controlling the distribution of transition metal elements and realize the modification of particle surface structure without the aid of heterologous ions. The results of characterization tests show that the content of LiMO2 phase inside the particles and the content of Li2MnO3 phase on the surface of the particles are successfully increased, and the surface induced formation of Li4Mn5O12 spinel phase or some disorderly ternary. The electrochemical performance of the modified sample is as follows: LR (pristine) shows specific discharge capacity of 72.7 mA·h·g−1 after 500 cycles at 1 C, while GR (modified sample) shows specific discharge capacity of 137.5 mA·h·g−1 at 1 C, and the discharge mid-voltage of GR still remains above 3 V when cycling to 220 cycles at 1 C (mid-voltage of LR remains above 3 V when cycling to 160 cycles at 1 C). Therefore, deliberately regulating the local state of the two phases is a successful way to reinforced the material structure and inhibition the voltage attenuation.

 

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