RESUMEN
In this study, an ionogel electrolyte (PAIM-X) consisting of 1-vinyl-3-methylimidazole bis (trifluoromethyl sulfonyl) imide ([VMIM][TFSI]), Polyacrylamide (PAAm), and MXene were prepared. The conductivity of PAIM-X and integral area of the voltammetric curve of the supercapacitor (PAIMSC) were improved by adding MXene. The addition of [VMIM][TFSI] enhanced the conductivity and applicable temperature of the ionogel electrolyte. At 90 °C, the conductivity of PAIM-4 can reach 36.4 mS/cm. In addition, spherical polyaniline with good electrochemical properties was synthesized and coated on graphite paper as an active substance. An all-solid-state supercapacitor was composed of PAIM-4, polyaniline electrode with 1.2 V potential window, pseudo-capacitors and high quality capacitors. The solvent 1-ethyl-3-methylimidazolium bis (trifluoromethyl sulfonyl imide) ([EMIM][TFSI]) and methanesulfonic acid (MSA) were introduced into the ionogel to promote the redox reaction of polyaniline (PANI). The mass specific capacitance of PAIMSC was 204.6 F/g and its energy density could reach 40.92 Wh/kg, which shows great potential for practical application at high temperature. The device had good rate performance and cycle performance, and its capacitance retention rate was still 91.56% after 10,000 cycles. In addition, the supercapacitor can work within the temperature range of -20 °C to 90 °C. These excellent electrochemical properties indicate that PAAm/IL/Mxene-X has broad application space and prospect.
Asunto(s)
Imidas , Temperatura , ElectrodosRESUMEN
Two-dimensional transition metal carbides/nitrides (MXene) have excellent physicochemical properties, but the restacking of MXene films restricts their development towards flexible supercapacitors with high energy density. Introducing Polyaniline (PANI) into the MXene layer and expanding the interlayer distance of the MXene can reduce the effect of restacking on the MXene after compounding. However, despite the excellent electronic conductivity of the composited MXene/PANI (MP), its internal slow ionic kinetics becomes a fundamental limitation of the electrochemical performance after the MP loading increases. To compensate for this weakness, MP films are often scaled down to a few micrometers in size (<2 mg cm-2), which limits their development. Here, we introduce α-Fe2O3/MnO2 (FM) into MP for the first time by designing a sandwich structure, which significantly improves the bulk capacitance. Due to a large number of active sites and good hydrophilic properties on the MXene surface, FM can interact with the MP. By complexing with MP, the accumulation and loss of FM can be reduced. At the same time, the effect of increasing loading on the electrochemical performance of MP can be compensated. The MXene-PANI/α-Fe2O3-MnO2/MXene-PANI (MP/FM/MP) electrode still exhibits high capacitive performance (661 F g-1, 3138 mF cm-3) when the MP loading reaches 5 mg cm-2, with excellent mechanical properties and increased flexibility. In addition, the corresponding symmetric supercapacitor also shows a remarkable energy density of 53.32 Wh·L-1 (17.45 Wh kg-1). This study provides a way to fabricate MXene-based electrodes with high loadings by designing sandwich-structured electrodes.
RESUMEN
The restacking of the MXene film limits its development to the high energy density of flexible supercapacitors. In order to promote the application of MXene films in portable electronic devices and miniaturized energy storage devices, it is necessary to increase the area capacitance of MXene films for the pursuit of high energy density. The introduction of α-Fe2O3-C-MoS2-PEDOT:PSS (FMP) into MXene significantly increases the area capacitance. Considering the large number of active sites on the surface of MXene and its excellent hydrophilicity, FMP can be well-compounded with MXene, and the accumulation and loss of FMP can be prevented. Meanwhile, it can reduce the performance degradation caused by the accumulation of MXene's own structure and greatly increase its capacitance value. It is worth mentioning that the MXene/FMP/MXene (M/FMP/M) sandwich structure on the carbon cloth is reasonably designed to show excellent performance. Therefore, the best M/FMP/M electrode could attain a breakthrough in the area capacitance (2700 mF cm-2 and 541 F g-1). At the same time, the electrode maintains a fine rate capability and fabulous flexibility. In addition, the symmetrical supercapacitors also show a significant energy density of 371 µW h cm-2 (12.36 W h·kg-1), making this sandwich structure electrode a promising candidate for high-energy-density devices.