The synthesis of NiO and NiCo 2 O 4 nanosheets by a new method and their excellent capacitive performance for asymmetric supercapacitor

Modified chemical synthesis of MnS nanoclusters on nickel foam for high performance all-solid-state asymmetric supercapacitors

“…In ASC, two electrodes with complementary potential windows, i.e., a positive potential from a pseudocapacitive electrode and a negative potential from a carbon-based electrode are integrated together to widen the potential window. [20][21][22] On the other hand, aqueous electrolytes used in ASCs evaporate gradually, resulting in a decrease in performance with time. Consequently, there is a need to fabricate all-solidstate ASCs with high C s , energy density, and power density.…”

β‐Co(OH)2 Nanosheets: A Superior Pseudocapacitive Electrode for High‐Energy Supercapacitors

“…Ultrafast charging/discharging capability (7 s) of the cell is also realized,f or example, at ap ower density of 8kWkg À1 the cell is callable of delivering the energy density of 15.64 Wh kg À1 .T his value is one of the best figures obtained for b-Co(OH) 2 or its composite-based asymmetrica ssemblies reportede lsewhere ( Table T1 in the Supporting Information). [19,26,28,35,50] Figure 4c shows the electrochemical impedance spectroscopy (EIS) curve of the asymmetric supercapacitor in the frequencyr ange of 0.1 Hz to 100 kHz at open-circuit conditions. The plot exhibits as emicircular curve followed by al inear curve, indicating an ideal capacitiveb ehavior of the supercapacitor.…”

“…Activated carbon (AC) is ap opular choice for EDLC components, in particular,f or the power component in the asymmetric configuration owing to its fascinating characteristics such as its wide range of chemical and electrochemical stabilities, high surfacea rea, high electricalc onductivity,t ailored meso-/microporous structure, low cost, etc. [2, [10][11][12] On the other hand, there are numerousm etal oxides and hydroxides (RuO 2 , [13] MnO 2 , [14] V 2 O 5 , [15] NiO, [16][17][18][19] Mn 3 O 4 , [20] Co 3 O 4 , [21][22][23] Bi 2 O 3 , [24][25][26] and Ni(OH) 2 [27][28][29][30][31][32] )h ave been exploited as pseudoca- pacitivee lectrodes, and af ew of them have been paired with AC too. Amongt hem, hydroxide-based materials have been extensively studied to improve the energy density of supercapacitors.…”

NiCo2O4/C Core‐Shell Nanoneedles on Ni Foam for All‐Solid‐State Asymmetric Supercapacitors

“…Spinel nickel cobaltite (NiCo 2 O 4 ) is one of the most representative active materials for pseudocapacitors because of its high theoretical capacity, cost‐effective, natural abundance, and environmental friendliness . Nevertheless, the capacitance of NiCo 2 O 4 is far less than its theoretical value, which is generally caused by intrinsically poor electronic conductivity which restrict the transfer of electrons . The storage mechanism of pseudocapacitors is confined to the few nanometers of surface, while the thickness of electrode materials is generally dozens of nanometers or more, which limit the effective utilization of active materials .…”