阴离子硫氧化还原与Li_(1-x)NiO_(2-y)S_y的结构稳定性:第一性原理研究（英文）

First-Principles Study: the Structural Stability and Sulfur Anion Redox of Li_(1-x)NiO_(2-y)S_y

高镍层状氧化物是电动汽车高能量密度锂离子电池正极材料的首选。本文通过第一性原理计算模拟了Li_(1-x)NiO_(2-y)S_y材料的脱锂过程。通过GGA+U计算分析了体系费米能级处的电子结构,充电过程中的氧化还原机制和热稳定性。在Li_(1-x)NiO_(2-y)S_y脱锂过程中,首次发现硫参与电荷补偿,抑制过渡金属的迁移,降低晶格扭曲幅度和提高体系中氧的稳定性。这种基于硫阴离子氧化还原对锂离子电池阴极材料电化学行为的调制有助于设计高稳定性的高镍正极材料。

Ni-rich layered oxides are the preferred cathode materials for high-energy-density lithium-ion batteries currently used in electric vehicles. In this paper, we present a systematic first-principles evaluation of the deintercalation process in the Li1-xNiO2-ySy. The partial density of states （PDOS） characters of the electrons near the Fermi level, redox behaviors, and thermal stability have been investigated within the GGA＋U scheme. The results show that the introduction of sulfur alleviates the lattice distortion during charging, suppresses nickel migration, and enhances the stability of oxygen according to the contribution of sulfur anion redox to the charge compensation for the overcharged Li1-xNiO2-ySy. This study provides a new insight on improving the stability of Ni-rich cathode materials by tuning of the electrochemical behaviors based on sulfur anion redox.