Similarities and differences between tannin- and resorcinol-based carbon aerogels: nitrogen-doping, electrical conductivity, and performance in a Zn-based electrochemical cell

Abstract

Carbon aerogels derived from organic precursors are gaining attention in various applications among others especially in energy storage. On one hand, the paper deals with the substitution of phenolic materials by tannin which could be beneficial to both the bioeconomy and the environment due to its low-cost, bio-based, and non-toxic characteristics. On the other hand, the comparative study aims to find out advantages and drawbacks of both aerogels, their electrical conductivity, morphology, performance in a electrochemical cell, and materials costs. The results illustrate that both nitrogen-doped aerogels exhibit pyridinic and pyrrolic functional groups, doping with melamine leads to higher nitrogen amount about 5 wt.-% compared against ammonia treatment (1-2.5 wt.-%). RF-based carbon aerogels exhibit almost twice the electrical conductivity of tannin-based carbon aerogels. The electrochemical performance of both carbon aerogels in a electrochemical cell is comparable to literature-reported cases. The capacitance of non-doped aerogels was found to be the highest reaching 239 F‧g-1 at a current density of 0.5 A g-1. Material costs of tannin-based electrodes are slightly lower compared to resorcinol-based.