Specific Adsorption-Oxidation Strategy in Cathode Inner Helmholtz Plane Enabling 4.6 V Practical Lithium-Ion Full Cells

Increasing the cutoff voltage effectively maximizes the available capacity of the state-of-art layered-oxide cathodes (LiTMO₂). However, the spontaneous dehydrogenation-oxidation of carbonates in the cathode inner Helmholtz plane (C-IHP) under high voltage/temperature leads to side effects, including weak cathode electrolyte interphase (CEI) and cathode structural collapse. Here, we report a specific adsorption-oxidation (Ad-O) mechanism that dominates the later CEI formation through molecular regulation in C-IHP. The two tailored additives with specific electron-rich groups will enter the C-IHP and mask the active sites of cathodes, thereby reducing the weak CEI generation from conventional carbonates. As-formed hierarchical CEI with inner LiF and outer B-F/-CN rich organic structure will further protect the aggressive cathode from harmful electrolyte corrosion under harsh conditions of high voltages (4.6 V) and elevated temperatures (60 °C). This synergistic strategy guided by the specific Ad-O mechanism enables 3.5 Ah LiNi_0.8Co_0.1Mn_0.1O₂/Graphite pouch cells, which remarkably achieve 270 Wh/kg with 450 cycles.