Hien Nguyen Rose Hills
Characterization of transport parameters
Advancement of lithium-based battery technology is extremely important as demand for safer and higher capacity batteries continues to increase. Commercial lithium-ion (Li-ion) technology has an inherit safety concern as the electrolyte mixture of ethylene carbonate, dimethyl carbonate, and lithium hexafluorophosphate is highly flammable. One way to address this problem is to switch to a nonflammable electrolyte while maintaining high levels of electrolyte performance. Performance metrics include conductivity, which is the reverse of the resistance to ion flow, transference number, which is a measure of the percentage of charge carried by a particular ion, and the salt diffusion coefficient, which tells how fast a molecule is moving with concentration gradient. All three metrics are needed to fully characterize an electrolyte.
Electrolytes formed out of polymers are of specific interest as they are nonflammable. The newest class of polymer electrolytes include mixtures of perfluoropolyethers and lithium salts with fluorinated anions. Our project is to determine the salt diffusion coefficient within the fluorinated electrolyte, particularly a system with a mixture of lithium bis(fluorosulfonyl)imide (LiFSI) in C8-DMC as a function of salt concentration and electrolyte thickness.