Impact of Dopants on Suppressing Gas Evolution from High-Nickel Layered Oxide Cathodes

Gas release from high-Ni layered oxide cathodes (LiNi x Mn 1- x-y-z Co y Al z O 2; x > 0.8) can jeopardize the overall performance and safety characteristics of the cell. A comprehensive assessment of rational cathode design with common dopants, such as Ni, Co, Al, and Mn, to suppress gas evolution is crucial for battery safety, yet it remains to be conducted. Here, we present an in situ gas analysis of nine high-Ni cathode materials with online electrochemical mass spectrometry (OEMS). We show that, regardless of the dopant, reactive oxygen release from the cathode lattice remains a critical process for gas evolution. A series of comparisons reveals that the intensity and onset point of gas release are strongly dependent on the cathode composition. Notably, Al and Mn are the most effective dopants to suppress gas evolution from the cathode at 4.4 V. We further highlight lattice stability limits, across these nine compositions, between 85% and 93% state-of-charge.