Macropore- and Micropore-Dominated Carbon Derived from Poly(vinyl alcohol) and Polyvinylpyrrolidone for Supercapacitor and Capacitive Deionization

We developed a kind of macropore- and micropore-dominated carbon (HPAC) derived from poly(vinyl alcohol) and polyvinylpyrrolidone for electric double-layer capacitive (EDLC) applications, e.g., supercapacitors and capacitive deionization (CDI). By comparing the EDLC performance of HPAC with those of ordered mesoporous carbon (OMC) and commercial activated carbon (AC), we evaluated the pore size effects. Cyclic voltammetry (CV) was employed for static and flowing CDI processes to identify the disparities between supercapacitors and CDI. HPAC exhibits a specific capacitance of 309 F g(-1) at a specific current of 0.5 A g(-1) (6 M KOH) in a three-electrode half-cell and has a salt removal capacity of 16.3 mg g(-1) (1.2 V, 500 mg L-1 NaCl), which is better than those of AC and OMC. Cycling tests of HPAC in supercapacitors and CDI show excellent stability. The properties of HPAC, fine, hydrophilic, macroporous, and microporous, endow HPAC with the promising possibility of use in supercapacitors and capacitive deionization. The disparities of supercapacitors and CDI include ionic species and concentrations and solution hydromechanics. CV analysis of static and flowing CDI equipped with HPAC electrodes suggests that increasing the salt concentration in CDI is beneficial for the carbon electrode to show high capacitance and to reduce the pumping energy during the CDI process.