Hierarchical 3D micro/nanostructured LiMn1-xFexPO4/graphene hybrid composite for high power Li-ion battery and its dynamic study by in-situ X-ray absorption and THz spectroscopies

锂离子电池具有高电压、高能量密度和良好的循环稳定性，是一类重要的储能器件。然而，作为电动汽车和混合动力汽车的电源，目前的LIB技术还需要进一步发展，以提高其功率密度。该战略项目旨在为大功率、安全的锂离子电池开发新型高性能、廉价的正极材料。我们建议将重点放在最有前途的正极材料之一，即LiMn1-xFexPO4 (LMFP)，与发达的LiFePO4相比，它的能量密度增加了20%。这可以为加拿大电池制造商提供竞争优势，使储能系统重量更轻，需要的电池更少。然而，LMFP确实有自己的挑战，包括(i)电子导电性差，（ii） Li+扩散缓慢。此外，对这种新型LMFP阴极材料中Li+离子和电子的动力学还缺乏深入的了解。在本项目中，我们将采用纳米技术开发一种新型的分层三维微/纳米结构的石墨烯涂层阴极材料LMFP，旨在解决上述挑战。同样重要的是应用新的太赫兹（THz）和同步辐射技术，以及理论建模，以进行独特的原位和非原位Li+和电子动力学研究。这将为设计高性能LMFP/石墨烯正极材料提供重要指导，为加拿大能源行业的公司提供竞争优势。特别是，太赫兹光谱是一种非接触式电探针，可以在亚皮秒到纳秒的时间尺度上测量电荷动力学和光电导率（传统方法不具备的时间分辨率）。这将有助于提高锂电池的安全性，并在经济上与目前的电动汽车内燃机相比具有竞争力。申请人将与三家加拿大工业伙伴合作，在对加拿大具有高度社会经济影响的部门申请。

Lithium ion batteries (LIBs) represent an important family of energy storage devices due to their high voltage, high energy density, and good cycling stability. However, as a power source for electric vehicles (EVs) and hybrid EVs, the current LIB technology still needs to be further advanced to improve their power density. This Strategic project aims to develop new type of high-performance and cheap cathode materials for high-power and safe LIBs. We propose to focus on one of the most promising cathode materials, i.e. LiMn1-xFexPO4 (LMFP), which provides up to 20% increase in energy density compared with the well-developed LiFePO4. This could offer Canadian cell manufacturers with a competitive advantage by allowing energy storage systems to weigh less and require fewer cells. However, LMFP does have its own challenges, including (i) poor electronic conductivity, and (ii) sluggish Li+ diffusion. Further, deep understanding of the dynamics of Li+ ions and electrons in this new LMFP cathode material is lacking. In this project, we will employ nanotechnology to develop a novel hierarchical 3D micro/nanostructured LMFP with graphene coating cathode materials, targeting to solve the above challenges. Equally important is the application of novel terahertz (THz) and synchrotron radiation techniques, and theoretical modeling, to perform unique in situ and ex situ studies of the Li+ and electron dynamics. This would provide significant guidance to design super performance LMFP/graphene cathode materials, giving Canadian companies in the energy sector a competitive advantage. Particularly, THz spectroscopy is a non-contact electrical probe that can measure charge dynamics and photoconductivity on sub-picosecond to nanosecond timescales (temporal resolutions that traditional methods do not have). This would help to make LIBs safe and economically competitive with today's internal combustion engine for EVs. The applicants will work with three Canadian industrial partners for applications in sectors of high socio-economic impact to Canada.