Restraining Lattice Oxygen Escape by Bioinspired Antioxidant Enables Thermal Runaway Prevention in Ni−Rich Cathode Based Lithium−Ion Batteries

Abstract

Ni−rich cathodes are hopeful materials for advanced lithium−ion batteries (LIBs) due to high capacity. Nonetheless, the chemical crosstalk triggered by reactive oxygen (O^*) represents a critical factor in thermal runaway (TR). Currently, there are few effective means to prevent this parasitic reaction. Here, inspired by the O^* scavenging effect of β−carotene in living organisms, it is innovatively identified that β−carotene can impede TR by restraining the escape of O^* during the thermal decomposition of nickel−rich cathodes. Using LiNi_0.6Co_0.2Mn_0.2O₂ as model and extending to higher nickel content cathodes (LiNi_0.8Co_0.1Mn_0.1O₂, LiNi_0.9Co_0.05Mn_0.05O₂), it is demonstrated that β−carotene can undergo an in situ oxygen copolymerization reaction to trapping O^*, thereby attenuating chemical crosstalk. Additionally, the generated oxygen copolymer can also adjust band center of the O 2p orbitals of delithiated cathode, alleviating the charge compensation behavior of oxygen anions, and thus delaying the phase transition of charged LiNi_0.8Co_0.1Mn_0.1O₂. As a result, the TR trigger temperature of NCM811∣Graphite pouch cell is increased from 131.0 to 195.0 °C and maximum temperature is reduced from 657.8 to 412.4 °C. This work introduces a new and simple strategy for designing functional additives to block TR, offering a promising avenue for advancing the safety of LIBs.