Impact of Aqueous and Acidic Treatment on Li-Transition Metal Oxides
Final Report Abstract
The combination of LiNi0.5Mn1.5O4 (LNMO) as cathode material with water-based electrode manufacturing processes is a promising strategy to increase the overall sustainability of nextgeneration high-energy lithium-ion batteries (LIBs) by the substitution of critical raw materials like cobalt as well as nowadays toxic processing solvents, i.e. N-methyl-2-pyrrolidone (NMP) and fluorine-containing binders as polyvinylidene fluoride (PVdF) by water and biopolymers. Herein, the pronounced sensitivity of LNMO upon water contact still poses a challenge that needs to be overcome before any possible industrialization. However, these processes are barely investigated on the atomic scale and thus mitigation strategies are rather based on empirical approaches than on understanding. Within this project we have made use of singlecrystalline LNMO particles with highly defined exposure of specific surface facets to investigate their interaction with water and typical processing additives and the consequent implications for aqueous processing. Thereby, we have first established a synthesis strategy that enables the careful design of such particles and their properties. Based on this, we provide insights regarding the impact of water on such materials, esp. highlighting the involvement of the transition metal oxidation state and the presence of phosphates during processing. Conclusively, we present an optimized aqueous processing strategy based on carrageenan (CAR) and citric acid (CA) as binder and phosphoric acid (PA) as additive.
