Mechanisms and Synthesis of Materials for Next-Generation Lithium Batteries Using Flame Spray Pyrolysis

由于电力的多功能性和现有的庞大电力基础设施，电力已成为传统能源和可再生能源的首选能源载体。交通运输部门的电气化是一种自然发展，可以利用各种来源的能源，减少二氧化碳排放量，防治城市空气污染。英国政府计划从2040年起禁止销售所有柴油和汽油汽车和货车，此前法国和德国也采取了类似举措。在全球范围内，电动汽车（EV）的数量预计将从2015年的约100万辆增加到2040年的3亿辆。实现这些目标需要大幅提高电动汽车电池的性能并降低其成本。锂离子电池（LIB）很有前途，但需要增强电极材料，特别是阴极，以满足下一代电动汽车和储能系统的功率密度和成本要求。该研究旨在产生基础知识，并开发实验和数值工具，用于LIB的高性能阴极材料的可控合成，具有扩展到大吞吐量生产的内在潜力。这些材料将基于分层的多元素金属氧化物（MO）和碳金属氧化物（CMO）。其中，具有各种金属含量和表面特征的镍锰钴氧化物（NMCs）将是研究的主要目标，这是主流汽车公司所青睐的，尽管研究和生产技术将适用于大类MO和CMO。常规地，MO可以经由固态、溶胶-凝胶和共沉淀方法及其组合，随后在没有或有碳涂层的情况下进行高温退火工艺来生产。这种多步合成路线是耗时和耗能的，并且需要对周围条件进行精细控制。一个有前途的替代方案是火焰喷雾热解（FSP），其中前体溶液被雾化以产生大量蒸发液滴，这些液滴被携带到加热的反应器中或用火焰燃烧以形成纳米颗粒。FSP可以提供一步式、高通量、易于操作、可扩展和连续的工艺，并提供广泛的前体解决方案。它允许良好的控制，重要的是，将生产过程与气相化学过程解耦，从而创造了以低成本大规模生产设计材料的潜力。该项目是剑桥大学（Simone Hochgreb在火焰合成; Adam Boies在纳米颗粒合成; Michael De Volder在纳米材料和电池）和UCL（Kai Luo在建模和模拟）之间的合作。结合实验和数值模拟研究，揭示粒子形成、生长和包覆的动力学过程和控制机制。在微观层面上，详细的运输和化学反应将被解开;在介观层面上，影响相变和颗粒生长的因素将被确定;在宏观层面上，关键过程的输入参数和时间尺度将与MO和CMO产品的质量联系起来。这些实验涉及尖端的原位和非原位测量，以定性和定量合成过程。建模和模拟包括液滴动力学和蒸发的先进介观模拟;以及前体热解、颗粒形成和生长的原子模拟。获得的基本见解以及开发的工具和生产技术将与四家公司（CATL，Echion Tech，PV 3 Technologies和STFET）合作，用于直接与电池性能指标相关的材料的受控火焰合成。这些公司的活动涵盖从2到9的技术准备水平，为研究提供了宝贵的投入，并为利用研究成果提供了多种途径。

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.