Construction of three-dimensional carbon materials-based conductive bonding network in flexible supercapacitor electrodes

Abstract

High-performance supercapacitors are widely studied, but few works have paid attention to the optimization of conductive bonding networks in the electrode to improve its electrochemical performance. Herein, a rationally designed three-dimensional (3D) conductive bonding network consisting of one-dimensional carboxylated carbon nanotubes (CNT-COOH) and two-dimensional reduced holey graphene oxide (rHGO) is introduced to porous carbon nanofiber/ultra-thin MnO2 nanosheets (PCNF/U-MnO2) electrode through vacuum filtration. The CNT-COOH/rHGO network endows the electrode with desired electron transport and ion diffusion properties for its advantages in 3D structures, conductivity and electrolyte wettability, which promote efficient use of PCNF/U-MnO2 active materials. Thus, PCNF/U-MnO2 in the electrode with CNT-COOH/rHGO network shows better capacitive performance than that of traditionally fabricated electrode with PTFE and acetylene black. Besides, CNT-COOH/rHGO network is conducive to structural stability of PCNF/U-MnO2 electrode, and it obtains a capacitance retention of 87% even after 4500 cycles. Then, an asymmetric supercapacitor with PCNF/U-MnO2 cathode and N, B-doped PCNFs anode has been assembled, which exhibits good flexibility using LiCl/PVA hydrogel as electrolyte and has a high energy density of 45 Wh kg−1 at a power density of 540.8 W kg−1. The strategy of CNT-COOH/rHGO network construction can be an effective and promising way beneficial to high-performance supercapacitor fabrication.