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...
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| Format: | Thesis |
| Language: | English |
| Published: |
2021
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| Subjects: | |
| Online Access: | http://umpir.ump.edu.my/id/eprint/34270/1/Studies%20on%20ionic%20transport%20and%20immittance.pdf |
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| Summary: | 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. |
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