Article ID: 20-64059
Recently, the single-walled carbon nanotube (SWCNT) has been the focus as a durable electrode with a high rate performance for the electric double layer capacitor (EDLC). However, it has not yet been clarified whether these reported outstanding properties are universal for all SWCNTs. The authors compared various self-standing SWCNT membranes (buckypapers) as the EDLC electrode to evaluate their stability to a floating high-voltage charge. Some SWCNTs exhibited an excellent rate performance even after the floating durability test, but other electrodes were degraded and showed a lower capacitance-retention. This variability in the durability for the SWCNTs can be attributed to the presence of residual metal impurities. Thus, it should be noted that the purity is a significant factor when using SWCNTs as the EDLC electrode, in addition to the nano-structure design from the viewpoint of operation stability.