Pseudocapacitive Electrodes Produced By Oxidant-Free Polymerization of Pyrrole Between the Layers of 2D Titanium Carbide (MXene)

Abstract

Pseudocapacitive electrodes based on electrochemically active organic materials are emerging for the energy storage applications.1 Organic materials are renewable, relatively inexpensive, lightweight, and their electrochemical properties can be tuned by changing their functional groups. Despite aforementioned advantages, they tend to degrade rapidly upon cycling mainly due to their poor conductivity. One option to improve their cycling performance is to graft/deposit them onto conductive carbon particles.2 Two-dimensional carbides and carbonitirides called MXenes, which generally offer metallic conductivity, may become a suitable option to replace carbon in pseudocapacitve electrodes to improve the electrochemical performance of the organic materials.3,4 Herein, we present simultaneous intercalation, alignment and oxidant-free polymerization of the pyrrole between the Ti 3 C 2 T x MXene layers by mixing pyrrole monomer with the Ti 3 C 2 T x colloidal solution. The optimized composition of the resulting composite yielded high volumetric and gravimetric capacitances of 1000 F/cm 3 and 416 F/g, respectively, at 5 mV/s. Furthermore, excellent capacitance retention of 92% was observed after 25,000 cycles at 100 mV/s. 1. M. Boota et al., Adv. Mater. (2015). DOI: 10.1002/adma.201504705 2. M. Boota et al., ChemSusChem, 8, 3576–3581 (2015) 3. M. R. Lukatskaya et al., Science., 341, 1502–1505 (2013) 4. M. Ghidiu, M. R. Lukatskaya, M.-Q. Zhao, Y. Gogotsi, and M. W. Barsoum, Nature, 516, 78–81 (2014)