Enabling 2.4-V aqueous supercapacitors through the rational design of an integrated electrode of hollow vanadium trioxide/carbon nanospheres

Abstract

Aqueous supercapacitors (SCs) exhibit several advantages, including high-power density, cycling durability, and safety; however, the shortage of low energy density inhibits their further application. Acquiring an excellent performance upon using simple strategies would be beneficial, but remains challenging. Here, an integrated electrode of hollow V 2 O 3 /carbon nanospheres (H-V 2 O 3 /C) was designed and synthesized for SCs. The introduction of carbon can increase the conductivity and stability, whereas the hollow structure endows H-V 2 O 3 /C with a high specific surface area and rapid transport of ions. Moreover, the H-V 2 O 3 /C integrated electrode can simultaneously work in both negative and positive potential windows. Benefiting from these advantages, the H-V 2 O 3 /C integrated electrode exhibits a specific capacitance as high as 708.6 F g −1 in a wide voltage window of −1.1-1.3 V. Furthermore, stemming from the multiple energy storage mechanisms, the aqueous integrated full SC device exhibits a wider potential window and higher energy density than the traditional (a)symmetric ones. Therefore, the proposed device delivers a wide voltage window of 2.4 V with an energy density of 96.8 W h kg −1 at a power density of 1204.6 W kg −1 , as well as superior cycling stability. This study enlightens the design and preparation of electrode materials, opening up a possible approach for developing wide-voltage aqueous SCs.

Ultrathin Polypyrrole Layers Boosting MoO3 as Both Cathode and Anode Materials for a 2.0 V High-Voltage Aqueous Supercapacitor

“…To quantitatively analyze the charge storage mechanism in the electrochemical processes of MP, a kinetic study of CV curves was carried out (Figure ). Generally, i ( V ) = k 1 v + k 2 v 1/2 , where I , v , and k 1 v and k 2 v 1/2 represent the current at a fixed potential, the sweep rate, and the surface-controlled and diffusion-controlled capacitive contributions, respectively . The equation can be further transformed into i ( V )/ v 1/2 = k 1 v 1/2 + k 2 .…”

“…However, the relatively low decomposition voltage (1.23 V) of water limits the operation voltage of aqueous supercapacitors, which correspondingly affects the energy density . It has been reported that the working voltage window can be expanded via modification of the electrode materials to build a more economical supercapacitor. − Generally, to broaden the potential window of a supercapacitor, it is necessary to increase its overpotential of the oxygen evolution reaction on the anode or the hydrogen evolution reaction on the cathode, respectively, under a steady state. , The cathode materials must then match with the anode materials to obtain asymmetric supercapacitors. While there has been considerable success in exploring electrodes for asymmetric supercapacitors with large device voltage and storage energy, device assembly requires much more complex processes compared to that of symmetric supercapacitors due to the different types of cathode and anode electrodes.…”

Interfacial engineering in amorphous/crystalline heterogeneous nanostructures as a highly effective battery-type electrode for hybrid supercapacitors

“…Development of hybrid HSCs that combine battery types and capacitor electrode materials is an effective strategy to improve these parameters. [7][8][9][10] Recently, tremendous efforts have been made to designing novel nanostructured, high-rate performance, and low-cost electrochemical materials, including metal phosphides, metal oxides and metal suldes. [11][12][13] In addition, transition metal phosphates (TMPs) have become the research emphasis due to their higher electrical conductivity and high capacity for HSCs.…”

“…Development of hybrid HSCs that combine battery types and capacitor electrode materials is an effective strategy to improve these parameters. 7–10…”

High‐Energy Aqueous Asymmetric Supercapacitors via Synergistic Design of Electrodes Derived from Hierarchical Vanadium Dioxide Nanocomposites

“…[34] In addition, the carbon coating can serve as an elastic buffer and protective layer of VO 2 anode, which efficiently alleviates its volume change and dissolution, respectively. [35] It would be quite interesting to investigate the preeminent electrode materials for effective ASCs by integrating the welldesigned nanocomposite structure with high electrochemical performance.…”