Xuesong E, Tengfei Lu, Sumei Wu, Yao Liang, Xiang Liu, Yang Wen, Weiwei Jiang, Zheng Wei, Yan Cui, Zhihua Zhang
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引用次数: 0
Abstract
Ni-rich cathode materials are among the most promising electrode materials for lithium-ion batteries due to their high capacity and low cost. Doping is considered to be one of the most effective strategies to mitigate cycling performance degradation and enhance the stability of the cathode material. In this study, group VIB transition metals (TM = Cr, Mo and W) were doped into pristine LiNiO2, and their effects on structural stability, electronic properties, lithium-ion diffusion, and intercalation voltage were systematically investigated using density functional theory and ab initio molecular dynamics simulations. TM doping introduces impurity bands, reducing the band gap and significantly enhancing conductivity. The doped systems have thermodynamic stability. Both intrinsic and doped systems exhibit anisotropic diffusion, the b-axis remaining the energetically favored path for Li+ migration. The diffusion activation energy of lithium-ion along b-axis decreases from 0.996 eV (pristine) to 0.696 eV (Cr), 0.608 eV (Mo) and 0.611 eV (W). Mo/W-doped systems exhibit Li+ diffusion coefficients and rates 6 orders of magnitude higher than the pristine system. The intercalation voltage is also increased by TM-doped system. These results provide a theoretical foundation for optimizing Ni-rich cathodes through doping strategies, emphasizing the superior efficacy of Mo/W dopants in enhancing conductivity and Li+ transport.
富镍正极材料因其高容量、低成本的特点,成为锂离子电池极具发展前景的材料之一。掺杂被认为是缓解循环性能下降和提高正极材料稳定性的最有效策略之一。本研究将VIB族过渡金属(TM = Cr, Mo和W)掺杂到原始LiNiO2中,并利用密度泛函理论和从头算分子动力学模拟系统地研究了它们对结构稳定性、电子性能、锂离子扩散和插层电压的影响。TM掺杂引入杂质带,减小带隙,显著提高电导率。掺杂体系具有热力学稳定性。本征体系和掺杂体系都表现出各向异性扩散,b轴仍然是Li+迁移的能量有利路径。锂离子沿b轴扩散活化能由0.996 eV (original)降低到0.696 eV (Cr)、0.608 eV (Mo)和0.611 eV (W)。Mo/ w掺杂体系的Li+扩散系数和速率比原始体系高6个数量级。掺入tm后,插层电压也有所提高。这些结果为通过掺杂策略优化富镍阴极提供了理论基础,强调了Mo/W掺杂剂在提高电导率和Li+输运方面的卓越效果。