Comparison of three different industrial lignin-based porous carbon electrodes for electrochemical applications

In order to fully utilize industrial lignin, a comparative study was conducted on the properties of porous carbon electrodes prepared by activating different industrial lignin as precursors. The results revealed that carbon electrodes prepared with sodium lignosulfonate (CM-S) exhibited superior specific surface area (SSA) (1,593.5 m 2  g −1 ) and pore volume (PV) (1.03 cm 3  g −1 ) due to the largest relative molecular mass (Mn = 4,539, Mw = 7,290), which is greater than that prepared with alkali lignin (CM-A) and kraft lignin (CM-K), and displayed a well-developed micro-mesoporous macropore hierarchy which was feasible for the efficiency of electron mobility. The electrochemical properties of materials were evaluated, and CM-S showed a mass-specific capacitance of 201 F g −1 at 0.2 A g −1 current density, along with an impressive capacitance retention rate of 54.7 % at 10 A g −1 current density, which is more potential than CM-A and CM-K (specific capacitances: 100 F g −1 and 75 F g −1 respectively). Additionally, maximum energy and power density of CM-S were measured to be 6.98 W h kg −1 and 2306 W kg −1 with excellent retention rate of 95.5 % after 10,000 charge–discharge cycles at a current density of 5 A g −1 . Comparatively, sodium lignosulfonate, compared with alkali lignin and kraft lignin, emerges as a more ideal precursor material for porous carbon electrode.