Nano-Confined Room-Temperature Ionic Liquids for Electrochemical Applications

Room-temperature ionic liquids (RTILs) and their derivatives are promising electrolytes for electrochemical devices including supercapacitors. Understanding the behavior of RTILs in these devices is critical for improving their performance. The energy density of supercapacitors can be improved greatly by using RTILs as electrolytes and nanoporous carbon as electrodes, but the mechanism of the charge storage using these materials is not well understood. In this dissertation, the diffusion and charging dynamics of RTILs in nanopores are studied. The results show that ion packing typically plays the most important role in ion diffusion. The study also demonstrates that the cyclic charging and discharging of a pore can exhibit a number of interesting features (e.g., sloshing of ionic charge along the pores during cyclic scans), which help explain experimental observations such as the negligible contribution of co-ions to charge storage at high scan rates. Solid electrolytes with both high ionic conductivities and excellent mechanical strength are needed in many electrochemical devices. The invention of ion gels featuring aligned polyanions immersed inside RTILs has shown promise in meeting this demand, but the mechanism behind their superior mechanical strength remains elusive. Using molecular simulations, it is discovered that the high elastic moduli of model PBDT ion gels originate from the RTIL-mediated interactions between the polyanions. This insight is useful for future design of ion gels to improve their transport and mechanical properties.

Name thesis:degree_name

Ph. D.

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Mechanical Engineering

Department dc:contributor.department

Mechanical Engineering

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2018

Author dc:creator

• He, Yadong

Chair dc:contributor.committeechair

• Qiao, Rui

Committee members dc:contributor.committeemember

• Madsen, Louis A.
• Tian, Zhiting
• Cheng, Jiangtao
• Lu, Chang

• Room-temperature ionic liquids
• nanopore
• ion gel
• molecular dynamics

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

vt_gsexam:14371

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/82419