The porous carbon derived from soy protein isolate “tofu” with electrochemical performance controlled by external pressure

Abstract

• The porous carbons were prepared from SPI-tofu. • The electrochemical performance of SPI tofu-based porous carbon can be adjusted by external pressure. • The influence of external pressure on electrochemical performance mainly comes from the change of pore length. • The porous carbons have great specific capacitance, energy density and cycle stability. Inspired by the preparation process of traditional tofu, we propose a tofu-based porous carbon (PC) preparation strategy. The PC (SPI-PC-x, x refers to the magnitude of pressure) with a three-dimensional (3D) structure is obtained by using soy protein isolate (SPI) with abundant protein content as raw material, and the best electrochemical performance can be optimized by adjusting the external pressure. We explored the regulation mechanism of pressure on the pore structure and the transport mechanism of electrolyte in the porous structure, aiming to provide a research basis for the fabrication of porous carbon or porous carbon composite with the action of protein (e.g SPI) flocculation. The results showed that PC with a suitable pore length has a higher effective specific surface area (SSA) and a faster ion transmission rate. The SPI-PC-200 has the maximum Cg of 280F g −1 in the three electrodes system with 6 M KOH as the electrolyte, and it has a good energy density of 16.5 Wh kg −1 when the power density is 450.0 W kg −1 in the two electrodes system with 1 M Na 2 SO 4 as the electrolyte.