Synthesis and characterization of PI gel carbonized material and its use in a supercapacitor

Abstract

In this study, a polyimide gel material with a high spatial network structure was synthesized. The pyrolysis process increased the material’s porous structure and specific surface area to improve the specific capacitance. The effects of pyrolysis temperature on morphology, structure, thermal, mechanical, and electrochemical properties were studied. The gel material is in the frozen state of the molecular chain from the frozen state to the moving state before 400°C. At the same time, pore structure formation with a weight loss rate of 11.9% in the decomposition state at 400°C–600°C, showing the breakage of the molecular chain and the decomposition of the polymer. With the increase of carbonized temperature, the pore structure becomes more compact while the pore size becomes smaller due to the reconstruction of the polymer structure. Meanwhile, due to the stable formation of carbon skeleton and the increase of carbon amount, the PI gel carbonized material’s thermal conductivity was improved to 1.458 $\mathit{W}/\left(\mathit{m}\mathrm{\cdot }\mathit{K}\right)$ , which was 330% higher than that of pure PI gel (0.339 $\mathit{W}/\left(\mathit{m}\mathrm{\cdot }\mathit{K}\right)$ ). Furthermore, the carbonized materials exhibit a specific capacitance of 66.17 $\mathit{F}\mathrm{\cdot }{\mathit{g}}^{-1}$ and show good redox reversibility, apparent concentration polarization and good ion diffusion effect during charging and discharging, suggesting it is a promising electrode material for supercapacitors.