Study on the ionic conduction properties of alginate based biopolymer electrolytes and its potential application in electrical double-layer capacitor

Energy storage device face several fundamental challenges in the present and the future, including the need for improved performance and safety benchmarks that take into account the introduction of environmentally friendly materials and creation of upgradable and easily recyclable products. To prevent environmental contamination problems, biopolymers are believed to be a key component on emerging new ways to overcome recent synthetic polymer electrolytes. Thus, alginate polymers have a great potential for development into solid biopolymer electrolytes (SBEs). The aims of this research are to develop and characterize the feasibility of alginate-based SBE systems doped with varying compositions of glycolic acid (GA) (System I) and plasticized with varying compositions of ethylene carbonate (EC) (System II) to be applied in an electrical double layer capacitor (EDLC). The solution casting technique was used to prepare both systems that possess flexible, transparent, and free-standing films. The lone pair oxygen from the host polymer (alginate) interacted with the H+ ion from the carboxylate group (COO----H+) of the charge carrier, which was shown by the shifting and disappearance of the peak in the Fourier-transform infrared spectroscopy (FTIR) analysis. The x-ray diffraction (XRD) peak intensity decreased gradually for both systems as the amorphous nature of the SBEs improved, demonstrating that movement of H+ ion through polymer matrix, lowered the degree of crystallinity (Xc) when introduced with GA and EC. The most amorphous SBEs discovered for System I and System II were composed of 20 wt. % GA (Xc = 26.99 %) and 5 wt. % EC (Xc = 18.85 %), respectively with smooth and homogeneous morphology without phase separation. Adding EC into the alginate-GA SBEs increased the Tg value due to the EC structure’s cyclic compound, which entangled the polymer chain leading to reduced flexibility in the complexes. Thermal stability was determined using thermogravimetric analysis (TGA) while the maximum decomposition temperature was elevated to 300 °C. These findings imply that the SBEs system is thermally stable and capable of meeting the device requirements. In System I, the optimum ionic conductivity (σ) of 5.32 x 10-4 S cm-1 at ambient temperature was achieved by adding 20 wt. % GA (GA-4). Meanwhile, the optimum ionic conductivity (σ) for System II (9.06 x 10-4 S cm-1) at ambient temperature was achieved by adding 6 wt. % EC (EC-3). Both SBEs systems obeyed the Arrhenius behaviour completely, with acceptable regression values (R2 ~ 1). The FTIR deconvolution approach was used to compute ionic transport parameters for both systems. The σ of both systems were predominantly influenced by ionic mobility (μ) and diffusion coefficient number (D) of H+ ion. Transference number measurement (TNM) was used to determine cation transference number (tн+), which was raised from 0.22 (GA-4) to 0.45 (EC-3). This proved that the plasticization effect successfully promoted greater H+ dissociation from the acidic salt which was utilized in this study. The linear sweep voltammetry (LSV) analysis demonstrated that Systems I and II were relatively stable at room temperature. For the EDLC cell fabrication, the highest ionic conducting sample from each SBEs was used. The plasticized SBEs, represented by System II Cell, outperformed the un-plasticized cell (System I Cell) in terms of power density (Pd), energy density (Ed), specific capacitance (Csp) and equivalent series resistance (ESR), which were improved by a higher current density that can withstand 10,000 cycles. These findings suggest that alginate-based SBE systems offer a significant potential for EDLC applications

Review on provision of solid-state polymer electrolytes for electrochemical energy storage devices

Solid-state electrochemical energy storage (EES) development has recently attracted considerable attention due to their practical application in portable energy devices. One of the issues with recent portable energy devices is high cost and adverse environmental effects during production, mainly brought on by the rise of the stationary applications. The electrochemical performance and mechanical stability of devices during charge/discharge are generally influenced by the design and method of synthesis, especially on the development of solid-state polymer electrolytes (SSPEs). The present review provides an overview of the solvent-free process used to make solid-state polymer electrolytes (SSPEs) and its challenges. Four methods are described: solution casting technique, heat-based method (hot-pressing and melt processing), spin coating, and 3D printing. Despite being the most recent approach for creating SSPEs, 3D printing is still a bottleneck for allprinted batteries and is still intensively studied. Hot-pressing and melt processing were employed as approaches for not only SSPEs preparation but also for electrodes preparation. Solution casting is the most straightforward approach to produce flexible and transparent SSPEs compared to the other three methods. Due to its convenience, many researchers have chosen this approach to prepare their SSPES. The solution was homogeneously placed onto a flat substrate and spread using a spin coater, which can be rotated at varying rotation speeds to generate a uniform film. This procedure is similar to the solution casting technique. The solution viscosity, spinning time, and spin coater speed all influence how thick the final coating is (production). Lastly, the challenges for SSPEs preparation development in EES devices are outlined

Ionic conductivity study of ethylene carbonate as a plasticizer in alginate bio-based polymer electrolytes

In this present work, the study of ionic conductivity based on bio-based Polymer electrolytes (BBPEs) containing with alginate doped glycolic acid (GA) and plasticized with ethylene carbonate (EC) is presented. The ionic conductivity of present work is determined through impedance spectroscopy over a frequency range from 50 Hz to 1 MHz. The addition of EC has improved the Cole-Cole plot for entire samples where it revealed the combination of CPE and bulk resistant in series for their electrical equivalent circuit. It is shown that the ionic conductivity increased from 10−5 to 10−4 S cm−1 upon addition of plasticizer into BBPEs system with the optimum conductivity is obtained at 9.06 × 10−4 S cm−1 for sample containing 6 wt.% of EC. The findings show that the present system has great potential to be used in application of polymer electrolytes system

Electrical Properties of A Novel Solid Biopolymer Electrolyte based on Algi-nate Incorporated with Citric Acid

In the present study, a novel solid biopolymer electrolytes (SBE) system has been introduced by doping citric acid into alginate polymer. The sample of alginate-citric acid SBE system was prepared via solution casting technique. By using Electrical Impedance Spectroscopy (EIS), the electrolytes of alginate-citric acid has been analyzed from 5 Hz to 1 MHz achieved highest conductivity value at 20 wt.% of 5.49 x 10-7 S cm-1. The temperature dependence of various composition citric acid was found to obey the Arrhenius rules with R2~1 where all SBE system is thermally activated when increasing temperature. The dielectric studies of the alginate-citric acid SBE system showed a non-debye behavior based on data measured using complex permittivity (ε*) and complex electrical modulus (M*) at selected temperature where there are no single relation was found in new biopolymer electrolytes system

Study on ionic conduction of alginate bio-based polymer electrolytes by incorporating ionic liquid

Biopolymer electrolytes is attracting a great deal of interest as a substitute for synthetic polymer electrolytes in electrochemical devices. They are carbon–neutral, sustainable, and reduce dependency on non-renewable fossil fuels, and easily biodegradable. The present work aims to develop the alginate bio-based polymer electrolytes (BBPEs) with the addition of various composition (2 to 10 wt%) of ionic liquid (1-butyl-3-methylimidazolium chloride) via solution casting technique. The ionic conduction study was characterized using electrical impedance spectroscopy (EIS) at different frequencies ranging from 50 Hz to 1 MHz. With the addition of 6 wt% 1-butyl-3-methylimidazolium chloride ([Bmim]Cl), the ionic conductivity of the BBPEs system was improved significantly from 5.32 X 10-5 S cm-1 to 2.03 X 10-3 S cm-1 at ambient temperature. The electrical properties analysis revealed that the ionic conductivity sample-based BBPEs has a good relationship with electrical properties formulism and shows non-Debye behavior where no single relaxation occurred in the present system

Ionic conductiviy of Alginate-NH4Cl polymer electrolyte

This study aims to produce a solid biopolymer electrolyte (SBE) by doping ammonium chloride (NH4Cl) into alginate. Solution casting was used to prepare the alginate–NH4Cl SBE system. Electrical impedance spectroscopy was performed to analyze the electrical properties of the SBE under the applied frequency range of 50 Hz–1 MHz. The incorporation of 8 wt.% NH4Cl enhances the ionic conductivity of the SBE up to 3.18 × 10-7 S/cm at ambient room temperature. Fourier transform infrared spectroscopy shows that complexation occurs between the hydroxyl (-OH), carboxylate (COO-) and ether linkage (C-O-C) functional groups due to the formation of inter- and intra-molecular hydrogen bonds between the biopolymer and the ionic dopant. The dielectric constant and dielectric loss increase with increasing dopant composition, thereby increasing the number of charge carriers and ionic mobility

Studies on the ions transportation behavior of alginate doped with H+ carrier-based polymer electrolytes

In the present work, amorphous bio-based polymer electrolytes (BBPEs) using alginate polymer as a matrix host and doped with varying amounts of ammonium iodide (NH4I) have been developed via the solution casting technique. The physicochemical properties of alginate-NH4I BBPEs were evaluated by using X-Ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared (FTIR), thermal gravimetric analysis (TGA), electrical impedance spectroscopy (EIS), and transference number measurement (TNM). The BBPEs film containing 25 wt % of NH4I possessed the highest ionic conductivity of 1.29 × 10−4 S cm−1, the highest amorphous phase, and good thermal stability of up to 234 °C. Based on the Nyquist fitting approaches, the ionic conductivity of the BBPEs was primarily influenced by the ion transportation, which was due to the interplay of segmental motion between the alginate and NH4I, and also the H+ hopping mechanism, as shown by FTIR. The proton transference number (tH+ = 0.41) suggests that alginate BBPEs are promising materials in electrochemical device applications

Conduction properties study on alginate incorporated with glycolic acid based solid biopolymer electrolytes

This present work focuses on the conduction properties investigation on solid biopolymer electrolytes (SBEs) based alginate doped with various composition of glycolic acid (GA). The film was successfully prepared via solution casting technique and was characterized for conduction properties by using impedance spectroscopy. Based on ionic conductivity study, sample containing with 20 wt. % of GA possessed an optimum ionic conductivity of 5.32 × 10-5 Scm−1 at ambient temperature (303 K). The dielectric analysis revealed the highest ionic conductivity sample based alginate-GA SBEs has the highest dielectric constant and loss and increased significantly when temperature increases at ambient temperature. The dielectric properties shows that the entire alginate-GA SBEs are non-Debye behavior where there is no single relaxation occurred in the present system

Influence of lithium bromide on electrical properties in bio-based polymer electrolytes

The present work reports on the influence of lithium bromide (LiBr) in electrical properties of alginate, as bio-based polymer electrolytes (BBPEs) system. Alginate bio-based were prepared with various composition of LiBr via solution casting technique. The ionic conductivity and electrical properties of the prepared BBPEs samples were investigated using electrical impedance spectroscopy over a frequency range from 50 Hz to 1 MHz. The maximum ionic conductivity of 7.46 x 10-5 S cm-1 was obtained at ambient temperature (303 K) for sample containing with 15 wt. % lithium bromide-doped alginate bio-based polymer electrolytes. The electrical analysis revealed the highest ionic conductivity sample based alginate-LiBr BBPEs has the optimum dielectric constant and loss and increases significantly when temperature increased. The dielectric properties show that the entire alginate-LiBr BBPEs are in non-Debye behavior condition where there is no single relaxation occurred in the present system

Enhancing proton conductivity of sodium alginate doped with glycolic acid in bio-based polymer electrolytes system

The investigation on bio-based polymer electrolytes (BBPEs) system based on alginate doped with a various composition of glycolic acid (GA) were carried out and prepared using solution casting technique. The BBPEs complexes were characterized by using fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC) and electrical impedance spectroscopy (EIS). The complexation was observed to have taken place between alginate and GA with apparent changes of the peak wavenumber, specifically at the –COO− of alginate functional group. Moreover, from the impedance analysis, it is evident that the sample which contains 20 wt. % of GA possessed the optimum ionic conductivity of 5.32 × 10−5 S cm−1 at room temperature with the lowest activation energy. The ionic conductivity increased by incorporating GA was demonstrated via the enhancement of their thermal stability as well as amorphousness. The findings of the present investigation suggest that alginate polymer has the potential to be applied as an electrolyte system for electrochemical devices applications