Wednesday, 4 October 2017
Prince George's Exhibit Hall D/E (Gaylord National Resort and Convention Center)
Silicon has the potential to replace the graphite as the anode material for LIB due to its high specific capacity and proper working voltage. However, the dramatic volume expansion during the Li-ion insertion and extraction has caused the poor cyclic stability. To improve the cyclic stability of Si anode, we embedded Si into a carbon matrix to form a Si-C composites. In this study, the silicon powders of micrometer size recovered from the silicon ingot slicing slurries and lignin, which is by-product of pulp industry, are employed to fabricate negative electrodes for lithium ion battery. The biomass would well mix with Si particles by magnetic stirring and ultrasonication, and then undergo a pyrolysis process to form Si-C composites. Depends on different carbonaceous precursors, the composites have different structures. The lignin-based Si particles are coated with a carbon layer, and the layer can not only suppress the volume change but also increase the electronic conductivity. The composite electrode exhibits outstanding cycle performance for capacity retention up to 60% after 51 cycles at 300 mA/g. On the other hand, the pyrolyzed lignocellulose formed an interconnected structure with Si particles, which provide extra space to accommodate Si volume variation. It showed excellent electrochemical performance with an initial charge capacity up to 1937 mAh/g and retaining 1275 mAh/g after 100 cycles at 300 mA/g. The utilization of renewable sources and industrial wastes for energy storage materials is well demonstrated in this study.