Abstract
The emergence of the fast-growing battery-powered EV industry creates huge pressures but also opportunities on metal/material production to meet the accelerated pace of battery manufacturing as evidenced by the construction of hundreds of “gigafactories” around the world. A recent report by Research & Markets projects the global battery market to grow from US$ 95.7 billion in 2022 to US$ 136.6 billion by 2027. Hydrometallurgy stands to play a major role in this context not only in terms of extraction of LIB metals like Ni, Co, Li but also in the area of production and recycling the active cathode materials themselves, such as LiNixMnyCo(1-x-y)O2 (NMC), LiNi0.8Co0.15Al0.05O2 (NCA), or LiFePO4 (LFP). Hydrometallurgy already is advocated as one of the most effective recycling technologies. Meanwhile hydrometallurgy is employed commercially in the preparation of the NMC hydroxide precursors via CSTR Coprecipitation, while hydrothermal synthesis is used to produce nanostructured LFP. Our HydroMET group over the past 12 years has undertaken several studies involving hydrothermal synthesis of electrode, but also ceramic electrolyte compounds on one hand as well as direct hydrothermal recycling of cathode materials. In this paper we plan to provide highlights of our hydrothermal processing research and discuss key features of hydrothermal reactions such as particle nucleation, growth and transformation mechanisms, the control of which can lead to process and product innovation but also provide ideas for an expanding domain of pressure hydrometallurgy.