材料科学
阴极
反铁磁性
过渡金属
电化学
氧化物
密度泛函理论
锂(药物)
磁矩
离子
电压
电池(电)
化学物理
凝聚态物理
电极
物理化学
冶金
热力学
计算化学
化学
电气工程
物理
内分泌学
工程类
催化作用
功率(物理)
有机化学
医学
生物化学
标识
DOI:10.1016/j.jmmm.2022.170107
摘要
Layered LiNi0.8Mn0.1Co0.1O2 (NMC811) has received considerable attention as a high-energy density cathode for next generation lithium-ion batteries (LiBs). The charge compensation process underlying the achievement of high capacity is generally described by a two-stage redox reaction between Ni2+/Ni3+ and Ni3+/Ni4+. However, the increase of the Ni for the high battery capacity often leads to a significant degradation of the NMC811 material. In this study, the magnetic property of the NMC811 battery system has been compared at low (4.3 V) and high (4.7 V) cut-off voltages. There has been a notable drop in the magnetic moment from 2.33 μB (pristine) to 2.11 μB and 2.07 μB for the cathodes cycled at 4.3 V and 4.7 V, respectively. The amount of low-spin Ni4+ increased in the cathode material after the high voltage cycling. A density-functional theory (DFT) simulation has been adopted to further understand the discrepancy in the magnetic moment upon the different voltages. The local magnetic moment () of the transition metals are evaluated with different atomic environments including the Li/Ni exchange. Also, the corresponding density of states (DOS) are provided. It is shown that the electrochemical performance will significantly deteriorate when a high antiferromagnetic interaction occurs with the Li/Ni exchange.
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