Carbon nanotube/felt composite electrodes without polymer binders

• Published in: Journal of power sources Vol. 162; no. 1; pp. 620 - 628
• Main Authors: Rosolen, J. Mauricio, Matsubara, E.Y., Marchesin, Marcel S., Lala, Stella M., Montoro, L.A., Tronto, S.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 08.11.2006; Elsevier Sequoia
• Subjects: Applied sciences; Capacitor; Carbon composite; Carbon nanotubes; Cup-stacked carbon; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Electrochemical conversion: primary and secondary batteries, fuel cells; Exact sciences and technology; Li-ion battery; Carbon nanotubes; Cup-stacked carbon; Carbon composite; Capacitor; Li-ion battery; Scanning electron microscopy; Nanotube; Carbon electrode; Secondary cell; Electrochemical characteristic; Lithium battery; Electrochemical properties; Propene; Capacitance; Chemical decomposition; Carbonates; Microstructure; Specific capacity
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2006.06.087

In this work we have investigated the suitability of composite electrodes consisting of cup-stacked and bamboo-like carbon nanotubes (CNT) synthesized directly onto a carbon felt for both lithium storage and double-layer capacitance applications. The CNT/felt composite electrode was prepared using catalytic chemical vapor decomposition on the carbon felt. The microstructure of the electrodes was characterized by scanning electron microscopy. Electrochemical characterization of the CNT/felt, either submitted or not to acid treatment for extraction of the catalytic particles used during the CNT growth, was carried out using 1 mol L −1 LiPF 6 in mixtures of ethylene carbonate, dimethyl carbonate, diethyl carbonate, and propylene carbonate. The carbon nanotubes loading and the type of CNT, whether open or closed, on the felt were the most significant factors regarding the electrochemical properties of the composite. With respect to the application of the composite to lithium storage, an anomalous behavior in the reversible specific capacity as a function of the current was detected. The capacity was found to be large at higher current values. The best reversible specific capacity was found for the open-CNT/felt (275 mAh g −1 at 0.16 A g −1, and 200 mAh g −1 at 0.82 A g −1), on an area of 0.634 mm 2. The double-layer capacitance of the CNT decreased with increasing current. In the case of the open-CNT with a CNT loading of 13.93 mg, the composite provided 40.3 μF cm 2 or about 12 F g −1 at 10 mA of polarization current using 1 mol L −1 LiPF 6 in mixtures of ethylene carbonate and dimethyl carbonate. For the closed-CNT with a CNT loading of 9.3 mg, the double-layer capacitance was 30 F g −1 at 20 mA in 1 M H 2SO 4.