Transition metal carbide – carbon fabrics for energy storage devices

Abstract

This study focuses on multifunctional composites based on transition metal carbides and carbon fiber, and their derivative energy storage devices. The carbon fabrics with a structural flexibility and excellent electrical conductivity was utilized as a three-dimensional substrate. Among two-dimensional transition metal carbides, titanium based Ti3C2Tx was directly applied as an active material in anode for lithium-ion battery without any binder and conductive additive, and showed high lithium storage ability and low capacity degradation. Furthermore, vanadium carbide nanowires, which were directly grown on carbon fabric by hydrothermal synthesis, were used as an active material in cathode for lithium-ion battery. Improved electrical conductivity affected to be high lithium storage capability and cyclic stability compared to commercial cathode materials. Moreover, a sulfur was inserted between two-dimensional titanium carbide and graphene oxide film, which have abundant surface functional groups, and this composite was utilized as a cathode active material, current collector, and permselective separator, respectively, for lithium-sulfur battery to suppress shuttle effect and enhanced long-cycle stability. In addition, the flexible lithium-sulfur battery integrated with a polymer electrolyte was fabricated, and electrochemically and mechanically analyzed. Carbon-nitrogen based covalent triazine frameworks were synthesized and fabricated as an electrode in supercapacitor after loaded on carbon fabric. To enhance the limitation in potential window from aqueous electrolyte, ionic liquid was hired. Polymer electrolyte, consisting of Nafion and ionic liquid, was prepared and applied to demonstrate the flexible supercapacitor. Increased operational potential window about 3 times resulted in increasing energy density about 6 times than conventional devices. Bimetal-organic frameworks were epitaxially grown on Ti3C2Tx and it was utilized as alternative noble metal based electrocatalysts in lithium-oxygen battery. Chemical bondings were derived with surface terminators of Ti3C2Tx and bimetal-organic frameworks and unpaired electrons through the solvothermal treatment enhanced the electrocatalytic activity. Therefore, the as-prepared bifuntional electrocatalyst exhibited superior performance and long cycle durability in lithium-oxygen battery.