Hybrid Carbon Nanostructures for Li-based Energy Devices
Lopez Silva, Gladys Anahi
Tour, James M
Doctor of Philosophy
In this work, we explored the use of carbon nanostructures as host materials, interlayers, and electrodes for high-performance lithium-sulfur (Li-S) batteries, as well as lithium-ion (Li-ion) capacitors. The adverse effects of CO2 on the environment have driven the transition to a more carbon-neutral society, where batteries and capacitors play a crucial role by making possible self-sustained renewable sources and electric transportation. However, these applications demand the development of devices with higher energy densities or that they can withstand harsh conditions. Herein, the use of nanostructures based on carbon nanotubes, graphene, and graphene nanoribbons to stabilize the sulfur cathode and the lithium metal anode is presented. Also, this thesis describes the use of the same structures to fabricate an all-carbon Li-ion capacitor capable of performing at high pressures. Our results indicate that 3D conductive carbon networks are essential to obtain high capacities and good rate capabilities; however, the cycle stability can only be obtained when the lithium polysulfide diffusion is mitigated. In the case of lithium metal anodes, a lithiated carbon nanotube interface can control the Li+ ion flux and suppress the growth of lithium dendrites. Lastly, pressure can improve the energy and power densities of Li-ion capacitors, but there is a balance where it can also affect the performance. Future research could undertake to explore more carbon materials for the stabilization of sulfur cathodes and lithium metal anodes and to identify the changes that the electrodes experience while performing in harsh conditions.