(90c) Synthesis and Design of Porous Nanospherical Particles for Vehicle Electrification

Shifting fossil energy to low-carbon clean energy is critical to prevent global warming, and increase sustainable economic growth. In transportation sector, the gains obtainable from advanced technologies applied to ICEs (internal combustion engines) such as downsizing and combustion control improvements cannot of themselves solve the issues of CO2 emissions. Electrification of the automobiles through proliferation of HEVs (hybrid electric vehicles), EVs (electric vehicles), and FCVs (fuel cell vehicles), coupled with development of sustainable sources of primary energy, will be essential in the future. In this talk, we will present the synthesis and design of porous nanospherical particles for electrification of the automobiles due to their large surface area and unique properties which arise from scaffold compositions. The first example will present a synthesis platform for mesoporous metallic alloy particles by combining the colloidal chemistry and aerosol technique. Electron tomography demonstrates that the resulting mesoporous particles are assembled from primary nanoparticles into three-dimensional (3D) networks. Such high-surface-area mesoporous particles exhibit excellent thermal stability and hold potential in catalysis of hydrogen storage. In the second example, we report a size-dependent synthesis method for hierarchically porous Si nanospheres (hp-SiNSs), which consist of a porous shell and a hollow core. On charge/ discharge cycling, the hp-SiNSs accommodate the volume change through reversible inward Li breathing with negligible particle-level outward expansion. Our mechanics analysis revealed that such inward expansion is enabled by the much stiffer lithiated layer than the unlithiated porous layer. LIBs assembled with the hp-SiNSs exhibit high capacity, high power and long cycle life, which is superior to the current commercial Si-based anode materials. The low-cost synthesis approach provides a new avenue for the rational design of hierarchically porous structures with unique materials properties.