(23b) Direct Deposit of Polyvinyl Alcohol/Silicon/Graphene Nanoribbon Nanofibers for a Facile Production of High Capacity Lithium‒ion Battery Anodes
AIChE Annual Meeting
Sunday, November 16, 2014 - 3:45pm to 4:00pm
Despite high theoretical capacity in lithium-ion batteries, silicon (Si) anodes are still vulnerable to severe capacity fading due to dramatic volume expansion and formation of solid–electrolyte interface on their surfaces.[1,2] Herein, we prepared a novel anode of polyvinyl alcohol (PVA)/Si nanoparticles (NPs)/graphene nanoribbon (GNR) nanofibers directly on the current collector via water–based electrospinning. This facile direct deposit approach using water as solvent eliminates the use of toxic solvents like NMP and by–passes conventional paste preparation steps such as sonication, blending, grinding and coating. Furthermore, PVA polymer acts as a dispersant to disperse highly loaded GNRs in water, which are unzipped from carbon nanotubes. Battery cells using PVA/Si/GNRs nanofibers exhibit an initial discharge capacity over 5000 mAh/g at 0.1C due to the synergy between well–dispersed GNRs and Si NPs. Hybrid nanofibers also exhibit much less charge transport resistance and higher peak current density than Si NPs. Even at 1C, they show a capacity around 1800 mAh/g owing to highly conductive GNRs within nanofibers, and a very stable cycle retention over 90% during 200 cycles. Such excellent cycle retention is attributed to cross–linked PVA covering Si NPs, which not only prohibits the volume expansion but also alleviates the formation of SEI layers.
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