Sodium phytate stabilizing lattice oxygen in high-nickel oxide cathodes for thermal runaway inhibition and high voltage operation.

The reactive oxygen species (O*) released from the nickel-rich layered oxide cathodes (LiNixCoyMn1-x-yO2, NCM) are responsible for triggering thermal runaway (TR) in lithium-ion batteries (LIBs). Specifically, the charge compensation from transition metal (TM) 3d to oxygen (O) 2p in NCM plays a pivotal role in O* release. Here, inspired by the strong chelating effect of sodium phytate (PN) on TM, we employ PN as a cathode additive to coordinate with nickel, thereby weakening the charge compensation of TM 3d to O 2p on the surface of LiNi0.8Co0.1Mn0.1O2 (NCM811) and ultimately enhancing battery safety. It is shown that the chelation successfully stabilizes lattice oxygen and suppresses the release of O*, preventing detrimental phase transitions in NCM811 and reducing heat generation from O* related crosstalk reactions. Consequently, the TR trigger temperature (Ttr) of NCM811 pouch cell with PN elevates from 125.9 to 184.8 °C, while the maximum temperature (Tmax) decreases from 543.7 to 319.7 °C. Moreover, the PN-derived modification layer allows NCM811 to maintain exceptional cycling stability for over 700 cycles at 4.6 V. This strategy provides a facile method for stabilizing lattice oxygen in NCM, inhibiting O*-triggered TR, and enhancing high-voltage performance.