2.4.3 Carbonization
As a renewable biomass material rich in a large amount of carbon,
cellulose is activated to prepare carbon-based fibers that also exhibit
excellent electric double layer performance. However, the performance of
directly using the prepared cellulose-based carbon fiber for energy
storage devices is not very good. In recent years, paper-based
supercapacitors prepared by compounding cellulose-based carbon fibers
with substances with high energy storage activity have also shown
excellent performance. Wu et al. [124] loaded carbonized
cellulose-based tissue paper (FCP) with
NiCO2O4 by hydrothermal method to obtain
FCP-NiCO2O4 paper-based electrode
(Figure 15B). On the one hand, carbonized FCP provides abundant sites
for the loading of highly conductive
NiCO2O4. On the other hand, carbonized
FCP favors the rapid movement of electrons during electrochemical
reactions. Thanks to the synergistic effect of carbonized FCP and
NiCO2O4, the
FCP-NiCO2O4 paper-based electrode showed
excellent area specific capacitance (3115mF cm-2) and
excellent energy density (1.2 mWh cm-3) and power
density (58.16 mW cm-3). As shown in Figure 15C,
Rabani et al. [125] uniformly grow cobalt oxide
(Co3O4) nanoparticles on the surface of
1DCNF. Then the resulting composite fiber is molded to obtain
CNF/Co3O4 paper matrix composite.
Finally, CNF/Co3O4 paper-based electrode
was obtained by carbonization treatment at 200°C. Thanks to the
excellent performance of CNF fiber and
Co3O4 after carbonization treatment. The
paper-based energy storage device assembled with this electrode can
provide a high specific capacitance of 214F g-1 at 1A
g-1.