Unravelling the Enhanced High‐Temperature Performance of Lithium‐Rich Oxide Cathode with Methyl Diphenylphosphinite as Electrolyte Additive
Unravelling the Enhanced High‐Temperature Performance of Lithium‐Rich Oxide Cathode with Methyl Diphenylphosphinite as Electrolyte Additive
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DOI：
10.1002/celc.201800061
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发表时间：
2018-06
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影响因子：
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通讯作者：
Shuaifeng Lou;M. Yulin;Zhenxing Zhou;Hua Huo;Pengjian Zuo;Xinqun Cheng;X. Qu;Yunzhi Gao;C. Du
中科院分区：
文献类型：
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作者：
Shuaifeng Lou;M. Yulin;Zhenxing Zhou;Hua Huo;Pengjian Zuo;Xinqun Cheng;X. Qu;Yunzhi Gao;C. Du
具有高能量密度的富锂氧化物阴极材料吸引了很多关注，然而，它们往往在循环期间，特别是在高温下遭受严重的容量衰减。在此，首次研究了甲基二苯基次膦酸酯（MDP）作为电解质添加剂，以提高富锂氧化物阴极在高温下循环期间的容量保持率。结果表明，当添加0.2wt.%的Ni时，Li 1.16Ni 0.2Co 0.1Mn 0.54O2正极材料的高温循环稳定性得到显著提高MDP，包括增强的库仑效率和容量保持率，在80次循环后从49.7%提高到93.9%。电化学和物理表征结合理论计算表明，由于P-O-物种和过渡金属元素之间的相互作用，MDP倾向于吸附在阴极表面，然后在约3.75 V（vs. Li/Li+）下优先氧化，在阴极表面原位形成坚固的人工界面层。 该界面相能有效地抑制电解液的分解，提高Li 1. 16 Ni 0. 2Co 0. 1 Mn 0. 54 O2与电解液在高温高压下的界面稳定性。
Lithium‐rich oxide cathode materials with high energy density attract much attention, however, they tend to suffer from serious capacity fading during cycling, especially at elevated temperature. Here, methyl diphenylphosphinite (MDP) is studied as electrolyte additive for the first time to enhance the capacity retention of lithium‐rich oxide cathode during cycling under high temperature. As a result, the cyclic stability of Li1.16Ni0.2Co0.1Mn0.54O2cathodes at elevated temperature is improved significantly when adopting 0.2 wt.% MDP, including an enhanced Columbic efficiency and capacity retention ratio promoted from 49.7 to 93.9 % after 80 cycles. Electrochemical and physical characterizations, combined with theoretical calculations, demonstrate that MDP tends to adsorb on the cathode surfacedue to the interaction between the P−O− species and transition‐metal elements, and then is oxidized preferentially at around 3.75 V (vs. Li/Li+), in situ forming a robust artificial interphase layer on the surface of the cathode. The interphases can effectively inhibit the electrolyte decomposition and greatly enhance the interface stability between Li1.16Ni0.2Co0.1Mn0.54O2and the electrolyte at high voltage and high temperature.