Abstract:

The 2.5 mm bamboo charcoal ultra-thick electrode material was prepared by direct carbonization of bamboo which preserved its straight pore structure. The bamboo charcoal materials Z-700, Z-800, and Z-900 were prepared at 700, 800 and 900 ℃, which were characterized by SEM, XPS, Raman spectra analysis. The results showed that the original bamboo structure was maintained after carbonization. Among them, the carbonized sample Z-900 owned a higher BET specific surface area(S_BET) of 483 m²/g, total pore volume(V_total) of 0.23 cm³/g, mesoporous pore volume(V_mes) of 0.05 cm³/g, and micropore volume(V_mic) of 0.18 cm³/g. Electrochemical performance tests showed that the specific capacitance of the prepared ultra-thick bamboo charcoal electrode Z-900 was as high as 22.0 F/cm² in the 6 mol/L KOH electrolyte with the current density of 10 A/m². When the current density was 200 A/m², the specific capacitance still reached 14.5 F/cm² and the capacitance retention rate was 65.9%. The symmetric supercapacitor Z-900//Z-900 assembled with ultra-thick bamboo charcoal electrode Z-900 owned a specific capacitance of 14 F/cm² at the current density of 10 A/m², which had a discharge time of 3 500 s, an energy density of 4.9 W·h/m², and a power density of 5 W/m². At the current density of 100 A/m², the coulomb efficiency could reach 99.8% after 10 000 cycles, and the capacitance retention was 88%, which demonstrated that Z-900 had an excellent electrochemical stability.

Key words: biomass, activated carbon, bamboo, ultra-thick electrode material, supercapacitor