Tailoring Cathode Interphase Chemistry for High-Voltage Li-ion Batteries

To unlock the potential of cyclability and energy density of Lithium-ion batteries (LIBs), cathode interphase engineering is pivotal. However, a comprehensive methodology for rational cathode interphase design remains elusive. In this study, we propose a unified framework for designing robust cathode interphases by elucidating the role of heavy transition metal (TM)-oxygen (O) hybridization [quantified by the energy gap between TM 3d and O 2p orbitals (Δδ)] and the chemical bonding strength [measured by the integrals of crystal orbital Hamilton population (ICOHP)] at the cathode surface. A large Δδ, coupled with a low ICOHP value, is identified as critical for forming an effective and stable cathode interphase. Guided by this principle, N-fluorobis(phenylsulfonyl)amine (NFA) additive with high Δδ [0.432 eV for LiCoO₂ (LCO) and 0.350 eV for LiNiO₂] and low ICOHP values (-1.461 eV for Co-N and -0.377 eV for O-Li) is stood out, which effectively passivates aggressive high-voltage cathodes. This strategy enables superior battery cyclic performance, with 4.55 V graphite||LCO pouch cells achieving over 357 cycles and 4.6 V graphite||LiNi_0.8Mn_0.1Co_0.1O₂ pouch cells exceeding 400 cycles in carbonate electrolytes with simple formulations. The proposed cathode interphase design framework offers a promising pathway toward high-voltage LIBs with ultralong lifespans.