Publication Date

2018-05-01

Availability

Embargoed

Embargo Period

2020-04-30

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PHD)

Department

Mechanical Engineering (Engineering)

Date of Defense

2018-03-23

First Committee Member

Xiangyang Zhou

Second Committee Member

Weiyong Gu

Third Committee Member

Hongtan Liu

Fourth Committee Member

Norman Munroe

Abstract

The present PhD dissertation reflects research efforts on Prussian blue analogues (PBAs) enhanced mediator supercapacitors(SCs). Two effects of PBAs were studied: (1) mediators provide extra capacitance to the electrodes of SCs; and (2) mediators provide extra free ions to the electrolyte in the SCs. In the first part of this dissertation, sixteen PBAs were synthesized and characterized by using proper methods. Respectively, PBAs-based supercapacitors were fabricated and analyzed by electrochemical characterization methods. The results of experiment showed that with doping 9% mediators in the electrodes the specific capacitance of the SCs increased by 85%. The correlation between capacitance increment and mediator was studied by using physic-chemical characterizations, linear sweep voltammetry and atomic simulation methods. It is concluded that the performance of mediator is mainly determined by the density of states at Fermi energy of core metal in PBAs. Also, the effect of PBAs as an ion supplier in mediator SCs was studied by comparing the performance of SCs with insufficient free ions. The results indicated that the mediator can provide extra free ions into the electrolyte. These ions help mitigate the deficiency of ions in the electrolyte during charging cycle and maintain the capacitance of SCs. An empirical method is proposed to predict the performance of SCs under different electrolyte concentrations.

Keywords

Prussian blue; mediator; supercapacitor

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