锂和镍的半径相近，才会产生大量混排，使得镍在interslab中起到支撑作用，才能实现高容量。然而这本身就是一种缺陷结构，高电压下锂离子脱出较多，就会形成NiO岩盐或尖晶石结构。过渡金属溶解不太了解，文献中看到说锰在低价态时能溶解，高价镍应该是氧化性很强吧。

高电压下，一般电解液不匹配，造成材料与电解液副反应增多，材料结构变化

高镍的氧化性较高，材料与电解液形成的固液界面发生反应。

这个主题很好，坐听高手回答

氧和镍的能级重叠，与电解液反应失去氧形成岩盐相NiO，导致性能衰减。

Highly reactive Ni4+ will be predominant at the end of charge leading to undesired side reactions with the electrolyte solution. This will eventually lead to a consumption of active material, gas evolution and capacity fading. Furthermore, the high temperature stability of the material will decrease with higher nickel contents leading to serious safety concerns
Just like in pure LNO high nickel contents in NCM will lead to a Li/Ni cation mixing. This will lead to a spinel formation on the surface and eventually to the formation of the inactive Fm(-)3m phase and capacity fade.
Starting with NCM811 a prolonged cycling will lead to cracks in the secondary particles along the grain boundaries. This leads to a continuous increase in surface area and hence more active sites for parasitic reactions.
我只是文献的搬运工，

It is well known that Li[NixCoyMnz]O2, especially with x > 0.6,readily reacts with air, resulting in the formation of Li2CO3 and LiOH on the cathode surface [18,19]. The formed LiOH reacts with LiPF6
and generates acidic HF in the electrolyte. In addition, Li2CO3 gives rise to severe swelling upon storage at high temperatures, especially in the charged state [20]. Table 2 exhibits the total residual
lithium amounts (LiOH and Li2CO3) on the cathode surfaces. The total residual lithium amount increased with increasing Ni content in Li[NixCoyMnz]O2 and increased drastically at Ni contents (x)
above 0.7.