Chalcogenide Dopant-Induced Lattice Expansion in Cobalt Vanadium Oxide Nanosheets for Enhanced Supercapacitor Performance

Abstract

We explore the effect of sulfur doping in Co 3 V 2 O 8 on the electrochemical performance of supercapacitors in terms of enhanced lattice spacing, electrochemical surface area (ECSA), electronic conductivity, and density of states. The sulfur-doped Co 3 V 2 O 8 (S-Co 3 V 2 O 8 ) nanosheets were grown in situ as a binderfree synthesis on nickel foam by the hydrothermal method. The electrochemical performance was analyzed in an aqueous alkaline electrolyte where the S-Co 3 V 2 O 8 electrode exhibited a specific capacity of 410 mAh/g at 2 A/g with enhanced rate capability and capacity retention of 94.2% at 5 A/g specific currents after 4000 cycles, whereas the undoped Co 3 V 2 O 8 electrode exhibited a specific capacity of 337.8 mAh/g at 2 A/g. The high capacity of S-Co 3 V 2 O 8 is attributed to the enhanced ECSA (by ∼45%) and improved electrical conductivity (by ∼22%) upon doping with sulfur. Furthermore, these results corroborated with density functional theory results. The calculations suggest an increase in lattice parameters and the introduction of additional density of states near the valence-band edge due to the doping of sulfur, resulting in a decrease in charge-transfer resistance. An asymmetric supercapacitor was fabricated, using S-Co 3 V 2 O 8 nanosheets as the cathode and activated carbon as the anode, which shows a high specific capacity (or capacitance) value of 485 mAh/g, an energy density of 36.4 W h/kg, and a power density of 740 W/kg at 2 A/g with 98.4% specific capacity retention after 4000 consecutive charge−discharge cycles. Furthermore, the analysis was extended in a nonaqueous medium for Li-ion storage where S-Co 3 V 2 O 8 exhibits a specific capacity of 994 mA h/g and a specific energy density of 828 W h/kg at 1 A/g making it a promising candidate for future high-energy storage systems. The concept of doping is extended to other chalcogenide (e.g., selenium) doping (Se-Co 3 V 2 O 8 ), which also shows improved device performance and makes this a versatile approach for high-performance devices.

MXene-drivenin situconstruction of hollow core-shelled Co3V2O8@Ti3C2Txnanospheres for high-performance all-solid-state asymmetric supercapacitors

“…S14c † exhibits the V 2p spectrum with the V 5+ and V 4+ states, indicating its steady valence state. 39 The Ti 2p spectrum in Fig. S14d † suggested the existence of Ti 3 C 2 T x MXene.…”

“…S14b † revealed the presence of Co 2+ and Co 3+ , but the weaker Co 2+ and satellite peaks compared to the pre-cycling indicated that Co 2+ was partially converted to Co 3+ , which agreed with the observations in the previous literature. 39 Fig. S14c † exhibits the V 2p spectrum with the V 5+ and V 4+ states, indicating its steady valence state.…”

Interfacially coupled thin sheet-like NiO/NiMoO4 nanocomposites synthesized by a simple reflux method for excellent electrochemical performance

“…S8†) and are summarized in Table S7 †48,49 The calculated value of ECASA for the NNMO-3 electrode is 9650 cm 2 , which is significantly larger than those of the other nanocomposite electrodes (NNMO-1: 6031 cm 2 , NNMO-2: 6863 cm 2 , and NNMO-4: 3949 cm 2 ), and therefore, signifies the higher availability of the electroactive sites for better capacitive behaviour among all the tested nanocomposite electrodes. 49 The maximum bulk BET specific surface area along with the mesoporous structure (Fig.…”

Isovalent anion-induced electrochemical activity of doped Co3V2O8 for oxygen evolution reaction application

“…The replacement of the oxygen with sulphur decreases the diffraction angle due to the increased d spacing. 33…”

“…Recently, Sharma et al reported that the doping of sulphur in Co 3 V 2 O 8 results in the improved conductivity of Co 3 V 2 O 8 . 33 As the change in conductivity alters the surface energy of the catalyst, S-Co 3 V 2 O 8 exhibits better OER performance. Additionally, the oxygen vacancies created due to vanadium in Co 3 V 2 O 8 further support the OER.…”