Fermentation assisted preparation of O and N riched porous carbon for high performance flexible supercapacitors

Abstract

Microorganisms have a superior biodegradability on biomass carbon. Herein, active yeast fermented cottonseed meal (FCM) by used as carbon precursor and K2CO3 as activator to prepare high O and N-doped porous carbon. The fermentation process not only decomposes the structural units of CM but also creates pore structure and increases the O, N group of the fermented CM (FCM). Most importantly, fermentation can improve the activation efficiency of K2CO3 and enhance the oxygen content. The optimized FCM-700-2 exhibits high O (19.45 at%) and N (3.13 at%) contents and hierarchical porous structure. The specific capacitance can reach up to 384 F g-1 in 6 M KOH. What’s more, we prepare a novel potassium citrate-agar gel electrolyte (PCA) with high operating voltage. The flexible symmetrical capacitor assembled with a commercial level mass loading of FCM-700-2 and PCA gel electrolyte delivers a high energy density of 27.4 Wh kg-1. Meanwhile, more than 109% of initial specific capacitance retains after 12, 000 cycles. This study provides a fermentation assisted strategy to prepare porous carbon materials, which has the advantage of simple, efficient, low activator ratio and high heteroatoms contents.