Electricity has emerged as a preferred energy vector for both conventional and renewable energy, thanks to its versatility and the vast existing electrical infrastructure. The electrification of the transport sector is a natural development to make use of energy from a wide variety of sources, and to reduce CO2 emissions and combat urban air pollution. The UK government plans to ban sale of all diesel and petrol cars and vans from 2040, following similar moves by France and Germany. Globally, the number of electric vehicles (EVs) is projected to rise from about 1 million in 2015 to 300 million in 2040. Achieving these goals requires dramatically improved performance and lowered costs of batteries for EV use. Lithium-ion batteries (LIBs) are promising, but enhanced materials for electrodes, especially the cathode, are needed to meet the power density and costs requirements for the next-generation EVs and energy storage systems.
The research aims to generate fundamental knowledge and develop experimental and numerical tools for the controlled synthesis of high-performance cathode materials for LIBs with the inherent potential to be scaled to large throughput production. The materials will be based on layered, multi-element metal oxides (MOs) and carbon-metal oxides (CMOs). Among these, the nickel manganese cobalt oxides (NMCs) with various metal contents and surface features, which are favoured by mainstream automotive companies, will be the main target for the research, though the research and production techniques will be applicable for a large class of MOs and CMOs. Conventionally, MOs can be produced via solid state, sol-gel, and co-precipitation methods and combinations thereof, followed by high temperature annealing processes without or with carbon coating. Such multi-step synthesis routes are time- and energy-consuming, and require delicate control of the surrounding conditions. A promising alternative is flame spray pyrolysis (FSP), in which a precursor solution is atomised to produce a large number of evaporating droplets that are carried into a heated reactor or burned with a flame to form nanoparticles. FSP can offer a one-step, high throughput, easy-to-handle, scalable and continuous process, with a wide range of precursor solutions. It allows good control and, importantly, decoupling of the production process from the gas-phase chemistry process, creating the potential to produce designer materials at scale and low cost.
The project is a collaboration between Cambridge University (Simone Hochgreb in flame synthesis; Adam Boies in nanoparticle synthesis; Michael De Volder in nanomaterial and batteries) and UCL (Kai Luo in modelling and simulation). A combined experimental and numerical study will be conducted to reveal the dynamic processes of and controlling mechanisms behind particle formation, growth and coating. At the microscopic level, the detailed transport and chemical reactions will be unravelled; at the mesoscopic level, factors affecting phase change and particle growth will be identified; and at the macroscopic level, the input parameters and time scales of key processes will be linked with quality of MO and CMO products. The experiments involve cutting-edge in-situ and ex-situ measurements to qualify and quantify the synthesis process. The modelling and simulation include advanced mesoscopic simulations of droplet dynamics and evaporation; and atomistic simulations of precursor pyrolysis, particle formation and growth. The fundamental insights gained, and tools and production techniques developed will be exploited for controlled flame synthesis of materials that are directly tied to battery performance metrics, in collaboration with four companies (CATL, Echion Tech, PV3 Technologies and STFET). These companies' activities cover the technology readiness levels (TRLs) from 2 to 9, providing valuable inputs to the research and multiple routes to exploitation of research outputs.
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