Term of Award
Master of Science in Applied Physical Science (M.S.)
Document Type and Release Option
Thesis (open access)
Copyright Statement / License for Reuse
This work is licensed under a Creative Commons Attribution 4.0 License.
Department of Chemistry
Committee Member 1
Committee Member 2
Lithium-Ion Batteries (LIBs) have broad applications such as portable electronic devices, electric vehicles, and for green energy storage from intermittent sources. Current LIBs are limited by their low capacity materials at both the anode and cathode. At the anode, graphite suffers from a low capacity of only 372 mAh g-1. The most commonly used cathode material is LiCoO2 which has a meager capacity of 140 mAh g-1. Thereby the broader applications of LIBs are limited due to these low capacities. It is imperative to develop higher capacity materials to further improve the performance of LIBs. Silicon is an ideal candidate to replace commercial anode materials due to its high theoretical capacity of 4200 mAh g-1 and vanadium pentoxide (V2O5) is a leading candidate for cathodes with an impressive capacity of 294 mAh g-1when two lithium ions are inserted per V2O5 unit. Unfortunately, silicon suffers from an extreme volume expansion of ~300% upon charging. This causes the material to crack leading to permanent capacity loss. V2O5 also suffers from some volume expansion issues, but the biggest obstacle to overcome is its low electrical conductivity and ion diffusivity. Herein, we report the fabrication of composite single, double, and triple-layer asymmetric membranes containing micron size silicon as anode materials and single-layer asymmetric membranes containing V2O5 as cathode materials. Anodes fabricated with an asymmetric membrane structure demonstrate a capacity of 610 mAh g-1 after 100 cycles with an 88% capacity retention at 0.5 C. Cathodes demonstrate a capacity of over 160 mAh g-1 with ~100% capacity retention at 0.5 C in 380 cycles. It is found that the choice of conductive additives and annealing temperature can have a significant effect on V2O5 particle morphology and cycling performance. Lower annealing temperatures and the addition of conductive graphene are shown to be beneficial to improving cycling performance. This scalable method may provide a universal answer for other anode and cathode materials with volume expansion issues.
Byrd, Ian. Asymmetric Membranes for High Capacity Lithium-Ion Battery Electrodes. Georgia Southern University, Statesboro, Georgia, 2017.
Research Data and Supplementary Material