b'A New Approach to CathodeNew understanding of the fundamental chemistry of the next-generation high-Interface Structure/Activityenergy lithium-ion batteries advances energy storage technologies through with Transient Kinetics transient kinetic experiments.H igh nickel content lithium-nickel-manganese-cobalt oxides (LiNi x Mn y Co z O2, NMC) are promising candidates as cathode materials for next-generation high-energy lithium-ion batteries. Significant challenges associated with the degradation of nickel rich NMC cathode materials include gradual capacity loss, as well as safety concerns resulting from reduced thermal TOTAL APPROVED AMOUNT:stability, which could lead to combustion at a high state-of-charge. The degradation $539,000 over 2 years of NMC cathode materials primarily comes from side reactions, cation mixing, transition metal dissolution, and gas evolution, such as carbon dioxide (CO2) and PROJECT NUMBER:oxygen. It has been reported that surface impurities of lithium carbonate are notably 20A44-050 involved in parasitic surface reactions, as well as in CO2 production. A key challenge PRINCIPAL INVESTIGATOR:in the development of robust and durable materials is a fundamental understanding Zongtang Fang of how structure and composition impact the surface reactivity.CO-INVESTIGATORS: Temporal analysis of products (TAP) and infrared spectroscopy were combined with Qiang Wang, INL density functional theory modeling to study the formation of surface carbonates Rebecca Fushimi, INL and hydroxides via CO2 and water adsorption on various NMC cathode materials. TAP is a pulse response approach for mechanistic investigation and precise kinetic COLLABORATOR: characterization in heterogeneous catalysis. In this project, TAP was applied for the University of Alabama first time in the application area of battery materials. Various NMC material with different nickel ratios (x:y:z = 8:1:1, 6:2:2, 5:3:2, 4:3:3, 1:1:1), as well as coated NMC materials, were studied to determine the role of different metals on carbonate and hydroxide formation and the role of water on carbonate formation.The reactivity of the material was found to increase with the nickel content while the capacity for CO2 had a distinct composition dependence. It was found that water creates more active sites for CO2 adsorption through hydrogen bonding of surface hydroxyls. Furthermore, water can stabilize the reactive surface and hydroxyl groups greatly decelerate the carbonate formation process. Detailed kinetics of these processes were reported. This fundamental kinetic characterization points to strategies for controlling the surface reactivity and stability of NMCs through exposure of select crystalline planes and precise control of water. This new understanding will be used in the future to enable superior design of the next-generation cathode materials.88'