Electrochemical activation to enhance the volumetric performance of carbon nanotube electrodes
By Chen, Daniel Rui; Adusei, Paa Kwasi; Chitranshi, Megha; Fang, Yanbo; Johnson, Kevin; Schulz, Mark; Shanov, Vesselin
Published in Applied Surface Science
Applied Surface Science
2020
Abstract
In recent years, the floating catalyst chemical vapor deposition (FCCVD) method has established itself as one of the most commercially viable methods to produce carbon nanotubes (CNTs). However, at the final stage of the FCCVD process, densification of the web of CNTs to form a sheet causes a significant loss in the active surface area of the CNTs. This loss of surface area reduces the density of active materials that can be infiltrated into the CNT sheet. Reducing the amount of active material in the sheet reduces the charge storage capacity and causes low volumetric performance for CNT sheet in energy storage applications. Here, we are reporting the use of an electrochemical activation technique to chemically functionalize the CNT surface and recover the lost surface area. Chemical functionalization separates the CNTs and thereby increases the density of active materials that can be integrated into the CNT sheet. In order to avoid deterioration of the CNT structure from excessive electrochemical activation, we have optimized the procedure by comparing the performance of four samples of CNT sheets prepared using different numbers of cycles of electrochemical activation (5, 10, 20, 40 cycles). The performance of the sheet was analyzed using specific capacitance measurement, electrochemical impedance spectroscopy (EIS) analysis, and UV