UCLA

Portable energy storage is of critical importance for the advance of renewable energy storage, consumer electronics, electric vehicles, and electric aviation, due to the increasingly complex and energy intensive products. Most of the mobile energy market relies on and is dominated by Li-ion battery technology, since its commercial introduction during the 1990s. However, the commercial Li-ion battery does not use lithium metal (3840 mA h g -1) as anode, but instead uses graphite anode or LiC6 (372 mA h g -1) when fully charged with only ~10% capacity compared to solid lithium metal. Thus, to increase the energy density of the battery and keep up with the improvement of future electronics, incorporation of lithium metal anode will have to be realized. However, the holy grail that is lithium metal anode is plagued by numerous hindrances. The chief problem being lithium dendrite growth as the result of charge and discharge during battery usage. The formation of lithium dendrite can result in the capacity fade of the battery due to electrode detachment, and severe safety concerns of battery short from dendrite penetrating the thin separator, and unwanted side reaction with the volatile electrolytes. These inherent problems can be addressed by incorporating solid-state electrolytes, where higher modulus can suppress the danger associated with lithium metal anode. In the first part of this thesis, we discuss the background and electrochemistry of a battery and the role of solid electrolytes compared to its liquid counterpart. In the second portion, we examine the application of nanomaterials and nanostructures in solid state electrolyte to enhance the low ionic conductivity of solid electrolyte to realize the effects of percolation pathways. In the third part, we examine the high surface area 3D network nanostructure with electronegative surface atoms that enhances ionic conductivity at the interface between the network and polymer. Lastly, we demonstrate the use of lithium trifluoromethane-bis-(sulfonyl)imide (LiTFSI) surface functionalized silica aerogel/polyethylene oxide (PEO) composite electrolyte. And its ionic conductivity (2 x 10 –3 S/cm) compared to the liquid and solid counterparts. In addition, we unravel the typically neglected ionic conductivity at extremely low temperature regime.