3D carboxyl and hydroxyl co-enriched graphene hydrogels as binder-free electrodes for symmetric supercapacitors

N/O co-enriched graphene hydrogels as high-performance electrodes for aqueous symmetric supercapacitors

“…Except for epoxy functional groups, the other oxygen-containing functional groups (carboxyl, carbonyl and hydroxyl) can enhance the wettability of electrode materials and generate abundant pseudocapacitances to enhance their energy density. [15][16][17] However, the low conductivity and high epoxy functional group content of GO severely restrict its application in electrochemical eld. At present, many studies have used high-temperature reduction method to solve this problem, which not only consumes a lot of energy but also causes irreparable damage to the sheet structure of graphene.…”

Corn Stalk-Based Carbon Microsphere/Reduced Graphene Oxide Composite Hydrogels for High-Performance Symmetric Supercapacitors

“…It is obvious that after 10,000 cycles of GCD at 10 A g –1 , the cell can maintain 102.2% of its initial capacitance, which is mainly attributed to the copious oxygen-containing functional groups of CSs; these groups can help electrode materials improve their hydrophilicity, wettability, and ion transmission speed . Besides, it can be seen from the inset of Figure d that the CV curve still maintains an excellent rectangular shape, which proves that the material has excellent cycling stability and is suitable for supercapacitor electrode material …”

“…58 Besides, it can be seen from the inset of Figure 6d that the CV curve still maintains an excellent rectangular shape, which proves that the material has excellent cycling stability and is suitable for supercapacitor electrode material. 59 We considered that the outstanding electrochemical properties of CS/rGOs can be attributed as follows:…”

High-performance supercapacitor electrode materials based on chemical co-precipitation synthesis of nickel oxide (NiO)/cobalt oxide (Co3O4)-intercalated graphene nanosheets binary nanocomposites

“…With regard to the charge-discharge mechanisms of Cu(OH) 2 /Cu as the used current collector and Co 3 O 4 and/or NiO as anchored metal oxide nanoparticles, which are written in full details in equation (10)(11)(12)(13)(14)(15)(16)(17), these reactions implicate the reversible faradaic redox reactions of Cu + ↔ Cu 2+ , Co 2+ ↔ Co 3+ , and Ni + ↔ Ni 2+ as the result of surface adsorption/desorption of OHion. In fact, these changes trigger the pseudocapacitive behavior of all the mentioned components present within the working electrodes.…”

“…On the other hand, agglomeration and re-staking in EDLCs result in lower specific capacitance and lower energy density than pseudocapacitors. Contrary to EDLCs, the J o u r n a l P r e -p r o o f specific capacitance and energy density of pseudocapacitors are much higher owing to their underlying charge storage mechanism [16,17]. Despite the given merits, pseudocapacitors, specifically transition metal oxides (TMOs), suffer from low power density and electroconductivity and poor long-term structural stability that cast a shadow on their advantages [18].…”