Hierarchical Microcellular Microporous Carbon from Polyamic Acid Cryogel and its Electrochemical Capacitance

Abstract

AbstractThe obtainment of a high specific surface area (SSA) without disrupting the conductivity of carbon is very challenging. Herein, an as‐synthesized polyamic acid (PAA) derivative dissolved in 1,4‐dioxane solvent was freeze dried to prepare a PAA cryogel, which allowed homogenous shrinkage of the texture and a high carbon yield upon carbonization. This work presents the successful template‐free preparation of a high‐surface area microporous carbon with a unique microcellular structure by simple carbonization treatment of a PAA cryogel. Upon increasing the carbonization temperature, the N content decreased, which was unfavorable for capacitance, but simultaneously, both the surface area and the crystallinity increased, which was beneficial in increasing the capacitance; these results are indicative of an interesting trade‐off relationship between surface area, conductivity, and the N content of the carbon. In particular, C‐PAA (1000) prepared by carbonization at 1000 °C from the PAA cryogel showed a high porosity of approximately 90.8 % and a remarkably high SSA of 2038 m2 g−1 along with high crystallinity and effective N doping favorable for good conductivity; this material thus illustrates a high specific capacitance of 248 F g−1 at 0.5 A g−1 and excellent stability in inorganic electrolyte.