Co(ii), Sn(ii), V(iii), Ni(ii), Mn(ii), and Ru(iii) species in urea-based quasi-ILs were investigated using cyclic voltammograms and X-ray absorption near-edge structure (XANES) spectra. The ...excellent pseudocapacitive characteristics of MnO sub(2)-graphene nanocomposite electrodes in ILs, associated with the large variation of Mn oxidation state during charge and discharge cycles, were also elucidated using in situXANES spectra.
This paper describes a fabrication protocol for a dipole-assisted solid phase extraction (SPE) microchip available for trace metal analysis in water samples. A brief overview of the evolution of ...chip-based SPE techniques is provided. This is followed by an introduction to specific polymeric materials and their role in SPE. To develop an innovative dipole-assisted SPE technique, a chlorine (Cl)-containing SPE functionality was implanted into a poly(methyl methacrylate) (PMMA) microchip. Herein, diverse analytical techniques including contact angle analysis, Raman spectroscopic analysis, and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analysis were employed to validate the utility of the implantation protocol of the C-Cl moieties on the PMMA. The analytical results of the X-ray absorption near-edge structure (XANES) analysis also demonstrated the feasibility of the Cl-containing PMMA used as an extraction medium by virtue of the dipole-ion interactions between the highly electronegative C-Cl moieties and the positively charged metal ions.
The electrochemical behavior of anodically deposited Mn oxide was studied in three ionic liquids (ILs): 2-methylpyridine-trifluoroacetic acid (P-TFA), 1-ethyl-3-methylimidazolium-dicyanamide ...(EMI-DCA), and 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI-BF(4)). In the aprotic and low-viscosity EMI-DCA IL, ideal pseudocapacitive behavior of the oxide electrode was observed; the specific capacitance, measured using cyclic voltammetry at a sweep rate of 5 mV/s, was 72 F/g. The operation potential window was as wide as 2 V, which is double that found in traditional aqueous electrolytes. Moreover, electrochemical stability of the Mn oxide electrode in EMI-DCA IL was excellent; after 600 redox cycles, the capacitance barely decayed. The charge storage mechanism of Mn oxide in the IL was examined using X-ray photoelectron spectroscopic (XPS) analyses. The results reveal that DCA(-), instead of EMI(+), is the primary working ion that penetrates into the oxide and compensates the Mn valent state variation. This is the first study that provides a detailed explanation of the pseudocapacitive properties of Mn oxide in IL.
Due to the ligand property of the DCA anion, both CuCl and NiCl2 are soluble in 1-ethyl-3-methylimidazolium dicyanamide (EMI-DCA) ionic liquid. Cyclic voltammograms of Ni(II), Cu(I), and ...Ni(II)+Cu(I), respectively, in EMI-DCA were recorded on the glassy carbon electrode at 30°C. It is interesting to note that the thermodynamic deposition potentials of Ni and Cu are very close to each other. This is especially favorable for the electrodeposition of Ni-Cu alloys without any additive. The Ni-Cu alloys were electrodeposited using bulk controlled-potential electrolysis experiments. Energy-dispersive spectroscopy (EDS) data indicates that the composition of the Ni-Cu alloys not only depends on the deposition potential, but also on the Cu(I) and Ni(II) concentrations in the melt.
A 3D network composed of V
O
nanofibers was manufactured on a novel conductive printing paper urea-LiClO
-PVA (ULP) deep eutectic solvent gel-doped graphite/printing paper, U-paper for use as ...electrodes linked with a ULP neutral gel electrolyte for 3D network V
O
wearable symmetric pseudocapacitors (WSSCs). The function of the ULP gel is not only that it can be doped into the conductive ink to decrease the resistance of the conductive printing paper but also that it increases the stability of V
O
-based electrodes. Moreover, 3D network V
O
WSSCs containing the ULP gel can support high operating voltages of 4.0 V with great specific capacitance (160 F/g) and offer a high energy density (355 W h/kg at 0.2 kW/kg). The 3D network V
O
WSSCs exhibit a superior cycling stability/durability after 5000 cycles (capacitance retention of ∼91%). Operando X-ray absorption spectroscopy experiments show the reversibility and pseudocapacitive properties of V
O
from the ULP gel and offer the information of the oxidation states of vanadium during charge-discharge cycles. The 3D network V
O
WSSCs with the ULP gel electrolyte show great potential prospective candidates for smarter 3D wearable energy-storage devices and Internet-of-Things applications.
To achieve high energy and power densities, we developed a high-voltage 2.5 V electrochemical pseudo-capacitor with a maximum energy density of 304 W h kg-1 based on MnO2 nanowires electrodeposited ...on nickel foam as electrode with a novel Li-ion quasi-ionic liquid as electrolyte.
Flexible electrochemical supercapacitors (FESCs) are emerging as innovative energy storage systems, characterized by their stable performance, long cycle life, and portability/foldability. Crucial ...components of FESCs, such as electrodes and efficient electrolytes, have become the focus of extensive research. Herein, we examine deep eutectic solvent (DES)–based polymer gel systems for their cost-effective accessibility, simple synthesis, excellent biocompatibility, and exceptional thermal and electrochemical stability. We used a mixture a DES, LiClOsub.4–2-Oxazolidinone as the electroactive species, and a polymer, either polyvinyl alcohol (PVA) or polyacrylamide (PAAM) as a redox additive/plasticizer. This combination facilitates a unique ion-transport process, enhancing the overall electrochemical performance of the polymer gel electrolyte. We manufactured and used LiClOsub.4–2-Oxazolidinone (LO), polyvinyl alcohol–LiClOsub.4–2-Oxazolidinone (PVA–LO), and polyacrylamide–LiClOsub.4–2-Oxazolidinone (PAAM–LO) electrolytes to synthesize an MnOsub.2 symmetric FESC. To evaluate their performance, we analyzed the MnOsub.2 symmetric FESC using various electrolytes with cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS). The FESC featuring the PVA–LO electrolyte demonstrated superior electrochemical and mechanical performances. This solid-state MnOsub.2 symmetric FESC exhibited a specific capacitance of 121.6 F/g within a potential window of 2.4 V. Due to the excellent ionic conductivity and the wide electrochemical operating voltage range of the PVA–LO electrolyte, a high energy density of 97.3 Wh/kg at 1200 W/kg, and a long-lasting energy storage system (89.7% capacitance retention after 5000 cycles of GCD at 2 A/g) are feasibly achieved. For practical applications, we employed the MnOsub.2 symmetric FESCs with the PVA–LO electrolyte to power a digital watch and a light-emitting diode, further demonstrating their real-world utility.
In this work, we successfully fabricated 3D network vanadium oxide (VO
x
) and manganese oxide (MnO
x
) nanofibers on conductive paper (PVA-acetamide-LiClO
4
-graphite/paper, PGP) as electrodes ...linked with an eco-friendly PVA-acetamide-LiClO
4
(PAL) deep eutectic solvent-based gel electrolyte for high-voltage wearable asymmetric supercapacitors (HVWASCs). An ecologically compatible deep eutectic solvent-based electrolyte with self-supporting electroactive species has been generally accepted as a unique type of cost-effective and green electrolyte that possibly involves a bulk concentration of the electroactive species and a large working potential window, thereby achieving a high performance. The HVWASCs are able to work with a large operating voltage of 4.2 V, and supply outstanding energy and power densities (245 W hkg
−1
at 0.18 W kg
−1
and 95.3 kW kg
−1
at 98 W h kg
−1
). The HVWASCs demonstrate remarkable cycling stability and durability after 6000 cycles, including bending and twisting (capacitance retention of 91.5%). The HVWASCs are a superior prospective candidate for wearable/flexible electronic devices and Internet of Things (IoT) applications.
A new approach for developing novel energy storage devices involving 3D network VO
x
and MnO
x
nanofibers on conductive paper (PVA-acetamide-LiClO
4
-graphite/paper, PGP) as electrodes linked with an eco-friendly deep eutectic solvent-based gel electrolyte for SCs is proposed and demonstrated.
In this work, we successfully fabricated 3D network vanadium oxide (VO x ) and manganese oxide (MnO x ) nanofibers on conductive paper (PVA–acetamide–LiClO 4 -graphite/paper, PGP) as electrodes ...linked with an eco-friendly PVA–acetamide–LiClO 4 (PAL) deep eutectic solvent-based gel electrolyte for high-voltage wearable asymmetric supercapacitors (HVWASCs). An ecologically compatible deep eutectic solvent-based electrolyte with self-supporting electroactive species has been generally accepted as a unique type of cost-effective and green electrolyte that possibly involves a bulk concentration of the electroactive species and a large working potential window, thereby achieving a high performance. The HVWASCs are able to work with a large operating voltage of 4.2 V, and supply outstanding energy and power densities (245 W hkg −1 at 0.18 W kg −1 and 95.3 kW kg −1 at 98 W h kg −1 ). The HVWASCs demonstrate remarkable cycling stability and durability after 6000 cycles, including bending and twisting (capacitance retention of 91.5%). The HVWASCs are a superior prospective candidate for wearable/flexible electronic devices and Internet of Things (IoT) applications.
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