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Aiming for increased nickel and lower cobalt content in layered transition metal oxide cathodes (NCM) is a feasible strategy for achieving increased energy density and cost competitiveness in commercial lithium‐ion batteries. However, the practical long‐term cycling of NCM cathodes suffers from severe capacity degradation due to irreversible interface phase transformation and unavoidable crack formation. Herein, an in situ modification strategy is used to form a uniform and conformal Li1.8Sc0.8Ti1.2(PO4)3 (LSTP) protective layer by interconnecting the single‐crystal‐layered LiNi0.6Co0.1Mn0.3O2 (SC‐NCM) particles. LSTP surface modification helps to construct a robust cathode‐electrolyte interphase thin film between the cathode and the electrolyte, which can prevent SC‐NCM corrosion by electrolyte, and the stability of the mechanics can improve the intergranular cracks caused by long cycles under harsh conditions. Moreover, the LSTP conductive modification layer facilitates the lithium‐ion transport among cathode particles, effectively enhancing the rate capability. Impressively, the LSTP modified SC‐NCM exhibits a high reversible capacity of 144.3 mAh g−1 at the high discharge rate of 5 C and maintains a capacity retention of 90.27% even at the ultrahigh charge voltage of 4.6 V operation after 500 cycles. Moreover, in a pouch‐type full battery, the graphite/LSTP modified SC‐NCM maintains a capacity retention of 89.6% after 1700 cycles. [ABSTRACT FROM AUTHOR]

Anionic redox activity can trigger structural instability in Li‐rich Mn‐based cathodes. Lattice oxygen activity can be tuned through liquid acid‐induced spinel phases and oxygen vacancies. However, the liquid‐acid‐modified surface is still attacked by the electrolyte. Besides, the underlying mechanism of spinel phase suppression of lattice oxygen activity is controversial. Here, a solid acid strategy for modification is proposed and the underlying mechanism is investigated in detail. Unique solid acid can in situ generate an interface protection layer and remarkably stabilize the structure. Theoretical calculations and experimental characterizations reveal that the spinel phase suppresses the irreversible loss of lattice oxygen by decreasing the O 2p non‐bonding energy level and enriching electrons at the layered/spinel phase interface. The inert layer on the surface prevents highly active On− from being attacked by electrolytes. The obtained material exhibits significantly reduced irreversible lattice oxygen release and improved electrochemical performance. After 300 cycles, a slow capacity fading of 0.177 mAh g−1 per cycle and suppressed voltage fading are achieved. This study reveals the regulation method and mechanism for the anion activity of oxide cathodes in next‐generation Li‐ion batteries. [ABSTRACT FROM AUTHOR]