Porous ZnO-Coated Co₃O₄ Nanorod as a High-Energy-Density Supercapacitor Material

Abstract

CoO with a high theoretical capacitance has been widely recognized as a promising electrode material for supercapacitor, but its poor electrical conductivity and stability limit its practical applications. Here, we developed an effective synthetic route to synthesize one-dimensional (1D) porous ZnO/CoO heterojunction composites. Benefiting from the heterostructure to promote the charge transfer and protect CoO from corrosion and the 1D porous structure to improve ion diffusion and prevent structural collapse in charge and discharge process, the as-prepared ZnO/CoO composites exhibited an excellent capacitive performance and good cycling stability. The specific capacitance of the ZnO/CoO-450 (1135 F g at 1 A g) was 1.4 times higher than that of CoO (814 F g), and the high-rate performance for ZnO/CoO-450 was 4.9 times better than that of CoO. Also, approximately 83% of its specific capacitance was retained after 5000 cycles at 10 A g. Most importantly, the as-fabricated asymmetric supercapacitor, with a ZnO/CoO-450 positive electrode and an activated carbon negative electrode, delivered a prominent energy density of 47.7 W h kg and a high power density of 7500 W kg. Thus, the ZnO/CoO composites could serve as a high-activity material for supercapacitor and the preparation method also offers an attractive strategy to enhance the capacitive performance of CoO.

Ultrathin Ni(OH)2 layer coupling with graphene for fast electron/ion transport in supercapacitor

“…To address this key issue, extensive studies have been done to develop high-performance electrode materials, including conducting polymers [12,13], heteroatomdoped carbon materials [14][15][16][17][18][19], transition metal phosphates [20], and transition metal oxides/hydroxides [21][22][23][24][25][26][27]. Lin et al [28] reported a nitrogen-doped mesoporous carbon, of which the specific capacitance can reach to 855 F g −1 at 1 A g −1 in 0.…”

Hybrid Supercapacitors Based on Interwoven CoO‐NiO‐ZnO Nanowires and Porous Graphene Hydrogel Electrodes with Safe Aqueous Electrolyte for High Supercapacitance

“…[23] Figure S22, Supporting Information, shows the SEM image of CNZO after 5000 cycles. At the same time, we also compare the test results with the reported work previously such as Co3O4/ ZnCo2O4/CuO-1//AC (35.82 Wh kg −1 at 800 W kg −1 ), [68] ZnO/ Co3O4-450//AC (47.7 Wh kg −1 at 750 W kg −1 ), [18] ZICO//N-G (40.5 Wh kg −1 at 750 W kg −1 ), [26] ZIF-NCS//AC (44.8 Wh kg −1 at 794.5 W kg −1 ), [69] ZnCo2O4//AC (52.36 Wh kg −1 at 650W kg −1 ), [70] PFNC//PFN (27.75 Wh kg −1 at 300 W kg −1 ), [71] and ZNCO//AC (35.6 Wh kg −1 at 187.6 W kg −1 ). By calculation, we obtained the energy density and power density of CNZO//PGH HSC, and the calculation results are shown in Figure 7g.…”

“…Compared with the other materials, metal oxides are favored by researchers because of their low cost and extremely high theoretical specific capacitance. [18] CoO is applied as electrode widely due to its ultra-high theoretical specific capacitance and high redox activity. ZnO is one of the typical semiconductor materials.…”

Self‐Supported, Sulfate‐Functionalized Nickel Hydroxide Nanoplates with Enhanced Wettability and Conductivity for Use in High‐Performance Supercapacitors

“…In the Ni 2p 3/2 spectra, the peaks at a binding energy (BE) of 855.9 and 861.5 eV (Figure e) are both ascribed to Ni II in Ni(OH) 2 . The O 1s peak (Figure S1) at BE=530.9 eV can be assigned to O in the hydroxide ions, and that at BE=532.0 eV corresponds to surface‐adsorbed carbonate anions . Notably, two peaks at BE=168.3 and 169.6 eV occur in the S 2p spectrum of SNO/NF‐2 (Figure e) but are absent in that of NO/NF, which indicates that S in the form of sulfate was present in SNO/NF‐2 .…”