Stable interstitial layer to alleviate fatigue fracture of high nickel cathode for lithium-ion batteries

High nickel cathodes can deliver higher capacity with lower cost than conventional LiCoO₂, however, the irreversible structural and morphology degradation with long-term cycling hinder their further application. In this paper, LiNi_0.815Co_0.15Al_0.035O₂ agglomerates are treated by LiNi_0.333Co_0.333Mn_0.333O₂ coating to get a stable interstitial layer without capacity loss. The interstitial layer is about 10 nm in thickness and has a layered (R-3m) structure, which can improve the chemical and mechanical stability of cathode materials with capacity retention of 88.5% after 200 cycles. The structural analysis and in-situ compression test proves that the morphology degradation is a fatigue process within long-term electrochemical reaction, and the coated sample has an excellent elastic recovery capacity thus leading to long cycle life.