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Restrained morphology and structural engineering of layered V2O5 by the oxidation of V-MXene to form a unique V2O5@V2C nanohybrids at different temperature and used as a cathode material for aqueous Zn-ion batteries (ZIBs).

Graphene sheet (GS)-ionic liquid (IL) supercapacitors are receiving intense interest because their specific energy density far exceeds that of GS-aqueous electrolytes supercapacitors. The electrochemical properties of ILs mainly depend on their diverse ions, especially anions. Therefore, identifying suitable IL electrolytes for GSs is currently one of the most important tasks. The electrochemical behavior of GSs in a series of ILs composed of 1-ethyl-3-methylimidazolium cation (EMIM(+)) with different anions is systematically studied. Combined with the formula derivation and building models, it is shown that the viscosity, ion size, and molecular weight of ILs affect the electrical conductivity of ILs, and thus, determine the electrochemical performances of GSs. Because the EMIM-dicyanamide IL has the lowest viscosity, ion size, and molecular weight, GSs in it exhibit the highest specific capacitance, smallest resistance, and best rate capability. In addition, because the tetrafluoroborate anion (BF4(-)) has the best electrochemical stability, the GS-[EMIM][BF4] supercapacitor has the widest potential window, and thus, displays the largest energy density. These results may provide valuable information for selecting appropriate ILs and designing high-performance GS-IL supercapacitors to meet different needs.

Owing to their unique nanosize effect and surface effect, pseudocapacitive quantum dots (QDs) hold considerable potential for high‐efficiency supercapacitors (SCs). However, their pseudocapacitive behavior is exploited in aqueous electrolytes with narrow potential windows, thereby leading to a low energy density of the SCs. Here, a film electrode based on dual‐confined FeOOH QDs (FQDs) with superior pseudocapacitive behavior in a high‐voltage ionic liquid (IL) electrolyte is put forward. In such a film electrode, FQDs are steadily dual‐confined in a 2D heterogeneous nanospace supported by graphite carbon nitride (g‐C3N4) and Ti‐MXene (Ti3C2). Probing of potential‐driven ion accumulation elucidates that strong adsorption occurs between the IL cation and the electrode surface with abundant active sites, providing sufficient redox reaction of FQDs in the film electrode. Furthermore, porous g‐C3N4 and conductive Ti3C2 act as ion‐accessible channels and charge‐transfer pathways, respectively, endowing the FQDs‐based film electrode with favorable electrochemical kinetics in the IL electrolyte. A high‐voltage flexible SC (FSC) based on an ionogel electrolyte is fabricated, exhibiting a high energy density (77.12 mWh cm−3), a high power density, a remarkable rate capability, and long‐term durability. Such an FSC can also be charged by harvesting sustainable energy and can effectively power various wearable and portable electronics.

Although manganese dioxide (MnO2) as cathode material holds great promise for aqueous Zn-ion batteries (ZIBs), the practical application is still impeded by its low tapping density, sluggish electron transfer and...

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