Supercapacitor Electrodes from Viscose-Based Activated Carbon Fibers: Significant Yield and Performance Improvement Using Diammonium Hydrogen Phosphate as Impregnating Agent

Abstract

Viscose fibers were impregnated with different concentrations of diammonium hydrogen phosphate (DAHP), carbonized, activated, and tested as high-performance electrode materials for supercapacitors. The yield of these activated carbon fibers (ACFs) could be increased by a factor of 14 by using DAHP compared to ACF without impregnation. These specific activation procedures yielded a high specific surface area of more than 2700 m2·g−1 with a pore size distribution (PSD) suitable for use as a supercapacitor electrode. The electrode materials were implemented in symmetric supercapacitors using TEMA BF4 as electrolyte and cyclic voltammetry measurements showed high specific capacitances of up to 167 F·g−1. Furthermore, the devices showed high energy densities of up to 21.4 W·h·kg−1 and high-power densities of up to 8.7 kW·kg−1. The supercapacitors featured high capacity retention (96%) after 10,000 cycles. These results show that ACFs made of viscose fibers, previously impregnated with DAHP, can be used as high-performance electrodes in supercapacitors for energy storage applications.