Ni-rich ternary oxides (LiNi_xCo_yMn_zO₂, x + y + z = 1, x ≥ 0.6) has received growing attention due to its high reversible capacity and high working voltage. However, the practical application of Ni-rich cathodes is still obstructed by the serious interfacial instability and structural degradation during long-term cycling. In this work, we propose a novel cyclic siloxane additive, i.e. 2,2,5,5-tetramethyl-2,5-disila-1-oxacyclopentane (TMDSi). With this additive, the capacity retention of NCM90||Li cells can be improved to 85% after 200 cycles at 1C (1C = 180 mA g⁻¹). The working mechanism of this novel additive has been clearly disclosed with the help of scanning electronic microscopy (SEM), transmission electron microscopy (TEM), electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS) and liquid nuclear magnetic resonance (NMR) techniques. The results show that TMDSi can effectively scavenge HF and suppress the dissolution of transition metal ions from the NCM90 cathode. Furthermore, its decomposition products can also form a uniform protective CEI film on the surface of NCM90 particles to maintain the complete morphology and reduce parasitic side reactions at the cathode interface. This bifunctional working mechanism makes TMDSi a promising electrolyte additive for Ni-rich cathode in Li-ion batteries.

富镍三元氧化物（LiNi _x Co _y Mn _z O ₂ , x + y + z = 1, x ≥ 0.6）由于其高可逆容量和高工作电压而受到越来越多的关注。然而，富镍正极的实际应用仍然受到长期循环过程中严重的界面不稳定和结构退化的阻碍。在这项工作中，我们提出了一种新型环状硅氧烷添加剂，即 2,2,5,5-tetramethyl-2,5-disila-1-oxacyclopentane (TMDSi)。使用这种添加剂，NCM90||Li 电池在 1C 下循环 200 次后的容量保持率可以提高到 85%（1C = 180 mA g ^-1). 借助扫描电子显微镜 (SEM)、透射电子显微镜 (TEM)、电化学阻抗谱 (EIS)、X 射线光电子能谱 (XPS) 和液体核磁共振 (核磁共振）技术。结果表明，TMDSi 可以有效地清除 HF 并抑制 NCM90 正极中过渡金属离子的溶解。此外，其分解产物还能在NCM90颗粒表面形成一层均匀的CEI保护膜，保持完整的形貌，减少正极界面的寄生副反应。这种双功能工作机制使 TMDSi 成为锂离子电池中富镍正极的一种很有前途的电解质添加剂。