Oxygen hole formation controls stability in LiNiO2 cathodes
Oxygen hole formation controls stability in LiNiO2 cathodes
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DOI：
10.1016/j.joule.2023.06.017
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发表时间：
2023-07-19
期刊：
影响因子：
39.8
通讯作者：
Morris, Andrew J.
中科院分区：
文献类型：
--
作者：
Genreith-Schriever, Annalena R.;Banerjee, Hrishit;Morris, Andrew J.
富Ni锂离子阴极材料实现高电压和高容量，但易于结构不稳定和氧损失。不稳定性的起源在于脱锂过程中O的显著氧化：对于LiNiO 2、NiO 2和岩盐NiO，基于最大局域化Wannier函数的密度泛函理论和动力学平均场理论计算产生约为2.5的Ni电荷态。+2，O在-2（NiO）、-1.5（LiNiO 2）和-1（NiO 2）之间变化。计算得到的X射线能谱、Ni K边谱和O K边谱与实验结果吻合较好。利用从头算分子动力学模拟，我们观察到锂镍氧化物（012）表面的氧丢失，两个表面氧自由基结合形成一个过氧化氢离子，过氧化氢离子被氧化形成氧，留下两个氧空位和两个氧离子.优先释放的1 O2是通过单重基态的过氧化氢离子和自旋守恒。
Ni-rich lithium-ion cathode materials achieve both high voltages and capacities but are prone to structural instabilities and oxygen loss. The origin of the instability lies in the pronounced oxidation of O during delithiation: for LiNiO2, NiO2, and the rock salt NiO, density functional theory and dynamical mean-field theory calculations based on maximally localized Wannier functions yield a Ni charge state of ca. +2, with O varying between-2 (NiO),-1.5 (LiNiO2), and-1 (NiO2). Calculated X-ray spectroscopy Ni K and O K-edge spectra agree well with experimental spectra. Using ab initio molec-ular dynamics simulations, we observe loss of oxygen from the (012) surface of delithiated LiNiO2, two surface O, -radicals combining to form a peroxide ion, and the peroxide ion being oxidized to form O2, leaving behind two O vacancies and two O2-ions. Preferential release of 1O2 is dictated via the singlet ground state of the peroxide ion and spin conservation.