Nanocellulose/polypyrrole aerogel electrodes with higher conductivity via adding vapor grown nano-carbon fibers as conducting networks for supercapacitor application

Abstract

Nanocellulose-based conductive materials have been widely used as supercapacitor electrodes. Herein, electrode materials with higher conductivity were prepared by in situ polymerization of polypyrrole (PPy) on cellulose nanofibrils (CNF) and vapor grown carbon fiber (VGCF) hybrid aerogels. With increase in VGCF content, the conductivities of CNF/VGCF aerogel films and CNF/VGCF/PPy aerogel films increased. The CNF/VGCF₂/PPy aerogel films exhibited a maximum value of 11.25 S cm⁻¹, which is beneficial for electron transfer and to reduce interior resistance. In addition, the capacitance of the electrode materials was improved because of synergistic effects between the double-layer capacitance of VGCF and pseudocapacitance of PPy in the CNF/VGCF/PPy aerogels. Therefore, the CNF/VGCF/PPy aerogel electrode showed capacitances of 8.61 F cm⁻² at 1 mV s⁻¹ (specific area capacitance) and 678.66 F g⁻¹ at 1.875 mA cm⁻² (specific gravimetric capacitance) and retained 91.38% of its initial capacitance after 2000 cycles. Furthermore, an all-solid-state supercapacitor fabricated by the above electrode materials exhibited maximum energy and power densities of 15.08 W h Kg⁻¹, respectively. These electrochemical properties provide great potential for supercapacitors or other electronic devices with good electrochemical properties.