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

Abstract

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.

Rational Design of Carbon Nanomaterials for Electrochemical Sodium Storage and Capture

“…In particular, hybrid CDI is analogous to the concept of hybrid SC, integrating high capacity battery‐type electrodes with capacitor‐type carbon electrodes in an asymmetric configuration, which can maximize the CDI performance and energy efficiency. In a similar manner to the historical advance in EDLC, various carbon materials, such as activated carbon, carbon aerogel, mesoporous carbon, CNFs, CNTs, and graphene, contributed to the development of CDI electrodes. Table 3 summarizes the CDI performance of representative carbon materials.…”

Recent Studies on Supercapacitors with Next-Generation Structures

“…The cylinder radius size plays a role of consolidation with capacitance, since the pore size reaches certain values. Additionally, the size of the slits affects the normalized capacitance, since the size is changed with various ranges [ 47 , 48 ]. Both the macropore and micropore structure is captured by scanning electron microscopy (SEM) images of highly pores activated carbons (HAPC).…”

“…Both the macropore and micropore structure is captured by scanning electron microscopy (SEM) images of highly pores activated carbons (HAPC). The images by SEM are 1 μm to 10 μm with different elements ( Figure 6 ) [ 47 ].…”

“… ( A – C ) Macro/micropole-dominated carbon on SEM (scanning electron microscope) images with different scale (10 μm and 1 μm) and ( D ) element mapping of highly porous activated carbon [ 47 ]. Reprinted with permission from Ref.…”

Nitrogen-doped graphene–TiOxNy nanocomposite electrode for highly efficient capacitive deionization

“…6 Currently, most reported and commercialized CDI electrode materials are based on various kinds of novel porous carbon electrodes. [7][8][9][10][11][12][13][14] Graphene, as a novel two-dimensional carbon nanomaterial, has been widely used as the electrode materials in batteries and supercapacitors due to its high electrochemical performance and large surface area. [15][16][17][18][19][20] Its heteroatom-doped derivative, especially nitrogen-doped graphene (NG), has also been investigated as electrode materials to achieve even better electrochemical performance in batteries and supercapacitors as opposed to graphene due to nitrogen-doped active sites and enhanced electrical conductivity.…”