Application of proton conducting polymeric electrolytes to electrochemical capacitors

Microwaved-Assisted Synthesis of Starch-Based Biopolymer Membranes for Novel Green Electrochemical Energy Storage Devices

The investigated starch biopolymer membrane was found to be a sustainable alternative to currently reported and used separators due to its properties, which were evaluated using physicochemical characterization. The molecular dynamics of the biomembrane were analyzed using low-field nuclear magnetic resonance (LF NMR) as well as Raman and infrared spectroscopy, which proved that the chemical composition of the obtained membrane did not degrade during microwave-assisted polymerization. Easily and cheaply prepared through microwave-assisted polymerization, the starch membrane was successfully used as a biodegradable membrane separating the positive and negative electrodes in electric double-layer capacitors (EDLCs). The obtained results for the electrochemical characterization via cyclic voltammetry (CV), galvanostatic charge with potential limitation (GCPL), and electrochemical impedance spectroscopy (EIS) show a capacitance of 30 F g-1 and a resistance of 2 Ohms; moreover, the longevity of the EDLC during electrochemical floating exceeded more than 200 h or a cyclic ability of 50,000 cycles. Furthermore, due to the flexibility of the membrane, it can be easily used in novel, flexible energy storage systems. This proves that this novel biomembrane can be a significant step toward ecologically friendly energy storage devices and could be considered a cheaper alternative to currently used materials, which cannot easily biodegrade over time in comparison to biopolymers.

Multifunctional Enhancement of Proton-Conductive, Stretchable, and Adhesive Performance in Hybrid Polymer Electrolytes by Polyoxometalate Nanoclusters

High ionic conductivity, good mechanical strength, strong electrode adhesion, and low volatilization are highly desired properties for flexible solid electrolytes. However, it is difficult to realize all these properties simultaneously, which needs a rational synergy of different electrolyte constituents. Here, we present the use of polyoxometalates as versatile enhancers to fabricate nonvolatile flexible hybrid polymer electrolytes with improved conductive, stretchable, and adhesive properties. These electrolytes are based on the molecular hybridization of a polyacrylate elastomer, phosphoric acid, and a commercial polyoxometalate H₃PW₁₂O₄₀ (PW). PW can serve as a nanosized plasticizer to favor the chain relaxation of polyacrylate and improve stretchability. Meanwhile, PW as a solid acid can increase the proton concentration and form a hybrid hydrogen-bonding network to facilitate proton conduction. Besides, the strong adsorption ability of PW on solid surfaces enables the electrolytes with enhanced adhesion. The hybrid electrolyte with 30 wt % PW shows a break stress of 0.28 MPa, a break elongation of 990%, and a conductivity of 0.01 S cm^-1 at 298 K, which are 1.8, 1.8, and 2.5 times higher compared to the case without PW, respectively. Moreover, PW enhances the adhesive strength of hybrid electrolytes on polypropylene, steel, and glass substrates. The flexible supercapacitors based on the hybrid electrolytes and polyaniline electrodes hold a stable electrode-electrolyte interface and exhibit a high specific capacitance of 592 mF cm^-2 and an excellent capacitance retention of 84% after 6000 charge-discharge cycles. These results demonstrate great potential of polyoxometalates as multifunctional enhancers to design hybrid electrolyte materials for energy and electronic applications.

An ionic liquid incorporated in a quasi-solid-state electrolyte for high-temperature supercapacitor applications

An ionic liquid incorporated in a cross-linked quasi-solid-state electrolyte is prepared for high-temperature application of supercapacitors.

Spectroscopic and Electrochemical Properties of (1-x)[PVA/PVP] : x[MgCl26H2O] Blend Polymer Electrolyte Films

Blend polymer electrolytes were prepared with different wt% compositions of [PVA/PVP-MgCl2·6H2O] : x% using solution cast technique. Structural, morphological, vibrational, thermal, and ionic conductivity and electrochemical properties were studied on the prepared polymer films. XRD revealed the crystalline nature of the polymer electrolyte films. The morphology and the degree of roughness of the prepared films were analyzed by SEM. FTIR and Raman studies confirmed the chemical complex nature of the ligands, interlinking bond formation between the blend polymers and the dopant salt. The glass transition temperature (Tg) of polymer electrolytes was confirmed by DSC studies. Ionic conductivity measurements were carried out on the prepared films in the frequency ranging between 5000 Hz and 50000 KHz and found to be maximum (2.42 × 10−4 S/cm) for the prepared film with wt% composition 35PVA/35PVP : 30MgCl2·6H2O at room temperature. The electrochemical studies were also performed on the prepared films. The galvanostatic charge/discharge performance was carried out from 2.9 to 4.4 V for the configuration Mg+/(PVA/PVP + MgCl2·6H2O)/(I2 + C + electrolyte).

Proton-conducting polymer electrolytes and their applications in solid supercapacitors: a review

Research on solid supercapacitors over the last few years has aimed to provide high performing and safely operating energy storage solutions for the fast growing application areas of consumer and micro-electronics, providing printable, flexible and wearable devices.

Printable thin film supercapacitors using single-walled carbon nanotubes

Thin film supercapacitors were fabricated using printable materials to make flexible devices on plastic. The active electrodes were made from sprayed networks of single-walled carbon nanotubes (SWCNTs) serving as both electrodes and charge collectors. Using a printable aqueous gel electrolyte as well as an organic liquid electrolyte, the performances of the devices show very high energy and power densities (6 W h/kg for both electrolytes and 23 and 70 kW/kg for aqueous gel electrolyte and organic electrolyte, respectively) which is comparable to performance in other SWCNT-based supercapacitor devices fabricated using different methods. The results underline the potential of printable thin film supercapacitors. The simplified architecture and the sole use of printable materials may lead to a new class of entirely printable charge storage devices allowing for full integration with the emerging field of printed electronics.

Synthesis and proton conductivity of anhydrous dendritic electrolytes

Water soluble PEG cored dendritic hexa-acid which comprises peripheral carboxylic acidic groups were prepared via nucleophilic substitution reactions. Novel anhydrous proton conducting electrolytes were prepared by incorporation of the heterocyclic protogenic solvent imidazole (Im) into PEG cored dendritic hexa acid, (PEG-HA), at several molar ratios of Im to-COOH units of PEG-HA. The complexation of PEG-HA and Im was illustrated by infrared spectroscopy (FT-IR). The materials are thermally stable up to 150 °C as evidenced by thermogravimetry analysis (TGA). Differential scanning calorimetry (DSC) results verified that the organic electrolytes are homogeneous and amorphous. The proton conductivities were characterized by means of AC impedance spectroscopy and a maximum conductivity of 1 × 10−3 S/cm was measured at 120 °C in the anhydrous state.