Additive engineering enables aggressive high-voltage LiCoO2 lithium-ion batteries

Abstract

The advancement of additive engineering in high-voltage LiCoO₂ (LCO)-based lithium-ion batteries (LIBs) is limited by the lack of effective guiding principles. Here, we report a lattice coupling mechanism for designing nitrile additives, systematically evaluating 20 candidates to quantify their enhancement effects on LCO performance. Key to this mechanism are two motif descriptors: the O 2p band center energy and the energy gap (ΔE) between the O 2p band center and the Co 3d band center, which significantly improve the structural and interfacial stability of the LCO cathode. Guided by this principle, we developed 1,2,2,3-propanetetracarbonitrile (PCN) as a representative additive, achieving 80% capacity retention in 4.55 V 1.0 Ah artificial graphite (AG)||LCO pouch cells after over 770 and 380 cycles at 25°C and 45°C, respectively. This work provides new insights into the exploration and evaluation of additive chemistry for high-voltage LCO cathode.