The effects of monosaccharides on the physico-electrochemical properties of chitosan based solid polymer electrolytes (SPEs)

Monosaccharides have shown their potential as plasticizers in solid polymer electrolytes (SPEs) due to the presence of numerous hydroxyl (OH) functioning groups. Glucose and fructose were used in this study. The effect of monosaccharides on physico-electrochemical properties of solid polymer electrolytes based on chitosan have been studied. Chitosan-based polymer electrolytes have been successfully plasticized using a solution-casting technique at six different weight percentages (0-30 wt.%). The result shows that 15 wt.% was the highest ionic conductivity achieved by both chitosan-glucose (CG) and chitosan-fructose (CF) systems. Lithium transference number (TLi +) analysis showed that CF had a high number of lithium ions compared to the CG system, with values of 0.26 and 0.14, respectively. In addition, Linear Sweep Voltammetry (LSV) analysis shows that the electrochemical stability for the CG system was 2.98 V compared to 3.20 V for the CF system. This discovery demonstrates that monosaccharides have the potential to be used as plasticizers due to the presence of several oxygen atoms in the structure, which act as a coordination site for cation interaction and can also improve the ion mobility and ionic conductivity of chitosan-based solid polymer electrolytes

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

Studies on ionic transport and immittance response of carboxymethyl cellulose/polyvinyl alcohol-based solid biopolymer electrolytes and its application

Polymer electrolytes (PEs) have been attracting attention owing to their wide application in areas of energy storage devices. Extensive research has been focusing on the application of petroleum-based polymers which give drawbacks including high costs, petroleum resources depletion and environmental problems. Thus, this present research has been carried out on biopolymers comprising of carboxymethyl cellulose (CMC)–polyvinyl alcohol (PVA) polymer blend as host which is prepared via the solution casting technique. The incorporation of ionic dopant (NH4NO3) followed by plasticizer, namely ethylene carbonate (EC) into the CMC–PVA also known as solid biopolymer electrolytes (SBEs) was investigated for the enhancement of the structural, optical and thermal properties via Fourier transform infrared (FTIR) spectroscopy, x-ray diffraction (XRD) spectroscopy, scanning electron microscopy (SEM), thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). This enhancement is important because it could influence the ionic and transport conduction properties of the SBEs that is measured by electrical impedance spectroscopy (IS). The highest conducting SBEs samples were fabricated in an electrical double layer capacitor (EDLC) where its performance was assessed via cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS). The complexation at the active functional group of C–O–C, –OH and –COO- is believed to influence the crystalline nature where the SBEs became more amorphous upon the addition of the NH4NO3 and EC. Morphology analysis showed that the developed samples have no phase segregation that is also due to the occurrence of complexation in the SBEs system. All SBEs samples were found to be thermally stable up to 300 °C and the ionic conductivity had increased to 1.70 10-3 S/cm with the addition of 30 wt. % NH4NO3 and further increased to 3.92 10-3 S/cm when added with 6 wt. % EC. Based on IR-deconvolution approaches, ionic transport elucidated that number of ions (η), ions mobility (μ) and diffusion coefficient (D) governed the ionic conductivity. The highest conducting samples both from NH4NO3 and EC were found to be stable up to 1.73 V and 1.89 V, respectively based on their electrochemical stability (potential windows). The plasticized SBEs demonstrated better cycling stabilities than un-plasticized SBEs at higher current density, 0.339 mA/cm2. As a result, the plasticized system exhibited higher specific capacitance, energy and power density. Therefore, the present research revealed the possibility of CMC–PVA as an electrolyte system by demonstrating favorable electrochemical properties in an EDLC practical application