Chitosan-based Polymer Electrolyte Research Articles

Highly conductive Poly(ε-caprolactone) and chitosan based polymer electrolyte for lithium metal battery

Poly (ε-caprolactone) (PCL) is an attractive polymer electrolyte material due to its ultralow glass transition temperature, high dielectric constant as well as excellent electrochemical stability, but its practical application has been greatly hindered due to the low ionic conductivity induced by the semi-crystalline structure. Herein, we elaborately modify PCL with chitosan (CS) to obtain an amorphous PCL-CS composite membrane, and develop a fast Li+ conducting quasi-solid polymer electrolyte (QPE) with lithium bis(trifluoro methane sulphonyl)imide (LiTFSI) and merely 10 wt% plasticizer. The optimized QPE with 50 wt% LiTFSI exhibits an ionic conductivity of 7.7 × 10−4 S cm−1, which is the highest among PCL-based polymer electrolyte. Fourier Transform Infrared spectroscopy and Raman spectra reveal that Li+ conducting via the solvation of partial plasticizer as well as contacted ionic clusters. In addition, its excellent stability and compatibility are validated by the integrated symmetric Li//Li cell that exhibits an ultra-long cycling for over 1850 h with no Li dendrite formation.

(Invited) Flexible and Safe Zinc Alkaline Solid-State Rechargeable Battery for Wearable Applications

Wearable electronics are one of the most rapidly growing industries, due to their extended use in everyday applications resulting in an increased demand for portable energy storage devices. Despite immense success in commercialization of Lithium-ion batteries (LIBs), conventional LIBs suffer from issues of cost and safety. The expanding need for cheaper, and safer energy storage devices led explorations towards alternatives. After careful considerations, Zinc (Zn)-Manganese dioxide (MnO2) based alkaline system was chosen to be investigated in this work due to its low cost, inherent safety, and high theoretical energy density. However, challenges associated with making the aforementioned system rechargeable and highly performing still remains. The work in this study is directed towards enhancing the overall performance of the Zn-MnO2 alkaline battery in addition to making it suitable for flexible and wearable applications. A highly ionically conducting polymer electrolyte ({5}CP) with excellent physical and electrochemical stability primarily comprising biopolymer chitosan is prepared by using a time and energy-efficient technique. Incorporation of this polymer electrolyte with Zn anode and MnO2 cathode enabled the successful preparation of a physically flexible cell. To obtain high cyclability and performance of the system; issues of inactive phase formations (MnxOy, ZnMnxOy), low active material availability, pronounced shape changes at the anode surface, and zincate ion transfer towards cathode were overcome by enhancing the electrochemically active layers in the system. The assembled cell comprising the enhanced fabricated layers; (i.e. a Zinc/Stainless steel mesh composite anode, a hierarchical binder-free bismuth and copper additives based MnO2 cathode, and a chitosan-based polymer electrolyte with calcium hydroxide additive) indicated excellent rate capabilities (486 mAh/g @ 0.1 A/g, 78% of the theoretical 2-electron capacity on MnO2), long cycling stabilities (70% retention over 1000 cycles), and good energy densities (155 – 400 Wh/kg @ 0.1 – 1 A/g). Moreover, a number of destructive tests such as being bent, hammered, pressurized, and punctured were conducted on the pouch cell fabricated using the above-mentioned layers to analyze the cells’ safety, reliability, and robustness. Results indicated not much deterioration in capacities. Additionally, when the cell was bent and tested for long performance; a stable discharge capacity (270 mAh/g @ 1 A/g) was obtained after 250 cycles, thus attesting to excellent cycling stability. The successful working of the fabricated cell was validated by lighting up an LED. The successful findings presented in this study can chart new pathways to the development of safe, flexible, cost-effective, and more environmentally responsible alternative energy storage sources for wearables.

Flexible and Safe Zinc/SS – Cu and Bi Incorporated Binder Free Hierarchical MnO2 Alkaline Solid-State Battery with High-Capacity Utilization and Long Cycle Life for Wearable Applications.

Wearable electronics are one of the most rapidly growing industries, due to their extended use in everyday applications resulting in an increased demand for portable energy storage devices. Despite immense success in commercialization of Lithium-ion batteries (LIBs), conventional LIBs suffer from issues of cost and safety. The expanding need for cheaper, and safer energy storage devices led explorations towards alternatives. After careful considerations, Zinc (Zn)-Manganese dioxide (MnO2) based alkaline system was chosen to be investigated in this work due to its low cost, inherent safety, and high theoretical energy density. However, challenges associated with making the aforementioned system rechargeable and highly performing still remains. The work in this study is directed towards enhancing the overall performance of the Zn-MnO2 alkaline battery in addition to making it suitable for flexible and wearable applications. A highly ionically conducting polymer electrolyte ({5}CP) with excellent physical and electrochemical stability primarily comprising biopolymer chitosan is prepared by using a time and energy-efficient technique. Incorporation of this polymer electrolyte with Zn anode and MnO2 cathode enabled the successful preparation of a physically flexible cell. To obtain high cyclability and performance of the system; issues of inactive phase formations (MnxOy, ZnMnxOy), low active material availability, pronounced shape changes at the anode surface, and zincate ion transfer towards cathode were overcome by enhancing the electrochemically active layers in the system. The assembled cell comprising the enhanced fabricated layers; (i.e. a Zinc/Stainless steel mesh composite anode, a hierarchical binder-free bismuth and copper additives based MnO2 cathode, and a chitosan-based polymer electrolyte with calcium hydroxide additive) indicated excellent rate capabilities (486 mAh/g @ 0.1 A/g, 278.9 mAh/g @ 2 A/g & 172.8 mAh/g @ 5 A/g), high capacity utilization (78% of the theoretical 2-electron capacity on MnO2), long cycling stabilities (70% retention over 1000 cycles), and good energy densities (155 – 400 Wh/kg @ 0.1 – 1 A/g). Moreover, a number of destructive tests such as being bent, hammered, pressurized, and punctured were conducted on the pouch cell fabricated using the above-mentioned layers to analyze the cells’ safety, reliability, and robustness. Results indicated not much deterioration in capacities. Additionally, when the cell was bent and tested for long performance; a stable discharge capacity (270 mAh/g @ 1 A/g) was obtained after 250 cycles, thus attesting to excellent cycling stability. The successful working of the fabricated cell was validated by lighting up an LED. The successful findings presented in this study can chart new pathways to the development of safe, flexible, cost-effective, and more environmentally responsible alternative energy storage sources for wearables.

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.

Impedance, circuit simulation, transport properties and energy storage behavior of plasticized lithium ion conducting chitosan based polymer electrolytes

In this work, energy storage devices based on plasticized chitosan biopolymer electrolytes were studied. The polymer electrolyte system of CS-LiClO4 with three different glycerol concentrations has been well prepared. The FTIR analysis revealed that the glycerol has interacted with the CS-LiClO4complex, which is confirmed bythe existence of several functional groups. The results of impedance spectroscopy were fitted with electrical equivalent circuits. The ion transport parameters were analyzed from the deconvoluted FTIR spectra. The highest ionic conductivity is obtained at 1.20 × 10−3 S cm−1 for CS-LiClO4 doped with 30 wt% glycerol (C3) with the breakdown voltage of 2.13 V. The transport parameters are observed to be influenced by the ionic conductivity, which verified from the deconvolution of v(ClO4−) band. The dielectric and electric modulus studies revealed the non-Debye behavior of the electrolytes.The tionvalue for C3 was 0.955 while telec was 0.045, and these values were used to further evaluate the contribution of ionsin ionic mobility and diffusion coefficient. At the scanned rate of 10 mV s−1, the maximum Cs value was obtained to be 98.99 F/g by the EDLC, very similar to the Cs (97.98 F/g) extracted from the 1st cycle GCD curve. Other parameters such as energy density and power density are specified for the fabricated EDLC device.

Improving EDLC Device Performance Constructed from Plasticized Magnesium Ion Conducting Chitosan Based Polymer Electrolytes via Metal Complex Dispersion.

The current work shows the preparation of plasticized chitosan-magnesium acetate Mg(CH3COO)2-based polymer electrolyte dispersed with nickel (Ni) metal complexes via solution casting. Investigations of electrical and electrochemical properties of the prepared polymer composite electrolyte were carried out. The structural and optical properties of the samples were studied using X-ray diffraction (XRD) and UV-Vis spectroscopy techniques. The structural and optical outcomes revealed a clear enhancement in both absorbance and amorphous nature of the samples upon the addition of Ni metal complexes. Through the simulation of impedance data, various ion transport parameters were calculated. The electrochemical performance of the sample was examined by means of transference number measurement (TNM), linear sweep voltammetry (LSV) and cyclic voltammetry (CV) measurements. The TNM analysis confirmed the dominance of ions as the main charge carrier in the electrolyte with tion of (0.96) compared to only (0.04) for tel. The present electrolyte was stable in the range of 0 V to 2.4 V, which was obtained from linear sweep voltammetry (LSV). A result from CV proved that the electrical double-layer capacitor (EDLC) has a capacitive behavior as no redox peaks could be observed. The presence of Ni improved the charge–discharge cycle of the EDLC due to its amorphous behavior. The average performances of the EDLC were recorded as 41.7 F/g, 95%, 5.86 Wh/kg and 628 W/kg for specific capacitance, coulombic efficiency, energy and power densities, respectively. The fabricated EDLC device was found to be stable up to 1000 cycles.

The study of EDLC device fabricated from plasticized magnesium ion conducting chitosan based polymer electrolyte

Plasticized biopolymer electrolytes based on chitosan (CS) doped with magnesium acetate (Mg(CH3COO)2) and various amounts of glycerol have been prepared for energy storage electrochemical double-layer capacitor (EDLC) application. In this work the dielectric and electrochemical properties have been examined using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and linear sweep voltammetry (LSV). It is confirmed from the frequency changing of the impedance spectra that relatively high dielectric constant has been recorded at low frequency region. From tan δ and M″ spectra, relaxation peaks are clearly seen. It has been found that as the glycerol concentration increased, the DC conductivity increases. In the fabricated system (CS: Mg(CH3COO)2: glycerol.), ions are responsible for charge carrying as the ion transference number is higher than the electron transference number. The electrochemical stability of the system extends to 2.4 V as shown in the LSV. The mechanism of the charge storage has been investigated and indicated that the non-Faradaic dominates where the specific capacitance is significantly affected by scan rate. The fabricated EDLC possessed a constant value of specific capacitance (78.2 F/g), energy density (8.8 Wh/kg), and ESR (78.2 F/g). The EDLC has an tremendous cycleability as high number of Columbic efficiency has accomplished. The value of efficiency of the EDLC has been in the range of 97%–99%.

Glycerolized Li+ Ion Conducting Chitosan-Based Polymer Electrolyte for Energy Storage EDLC Device Applications with Relatively High Energy Density.

In this study, the solution casting method was employed to prepare plasticized polymer electrolytes of chitosan (CS):LiCO2CH3:Glycerol with electrochemical stability (1.8 V). The electrolyte studied in this current work could be established as new materials in the fabrication of EDLC with high specific capacitance and energy density. The system with high dielectric constant was also associated with high DC conductivity (5.19 × 10−4 S/cm). The increase of the amorphous phase upon the addition of glycerol was observed from XRD results. The main charge carrier in the polymer electrolyte was ion as tel (0.044) < tion (0.956). Cyclic voltammetry presented an almost rectangular plot with the absence of a Faradaic peak. Specific capacitance was found to be dependent on the scan rate used. The efficiency of the EDLC was observed to remain constant at 98.8% to 99.5% up to 700 cycles, portraying an excellent cyclability. High values of specific capacitance, energy density, and power density were achieved, such as 132.8 F/g, 18.4 Wh/kg, and 2591 W/kg, respectively. The low equivalent series resistance (ESR) indicated that the EDLC possessed good electrolyte/electrode contact. It was discovered that the power density of the EDLC was affected by ESR.

Metal Complex as a Novel Approach to Enhance the Amorphous Phase and Improve the EDLC Performance of Plasticized Proton Conducting Chitosan-Based Polymer Electrolyte.

This work indicates that glycerolized chitosan-NH4F polymer electrolytes incorporated with zinc metal complexes are crucial for EDLC application. The ionic conductivity of the plasticized system was improved drastically from 9.52 × 10−4 S/cm to 1.71 × 10−3 S/cm with the addition of a zinc metal complex. The XRD results demonstrated that the amorphous phase was enhanced for the system containing the zinc metal complex. The transference number of ions (tion) and electrons (te) were measured for two of the highest conducting electrolyte systems. It confirmed that the ions were the dominant charge carriers in both systems as tion values for CSNHG4 and CSNHG5 electrolytes were 0.976 and 0.966, respectively. From the examination of LSV, zinc improved the electrolyte electrochemical stability to 2.25 V. The achieved specific capacitance from the CV plot reveals the role of the metal complex on storage properties. The charge–discharge profile was obtained for the system incorporated with the metal complex. The obtained specific capacitance ranged from 69.7 to 77.6 F/g. The energy and power densities became stable from 7.8 to 8.5 Wh/kg and 1041.7 to 248.2 W/kg, respectively, as the EDLC finalized the cycles.

PH and Swelling Study of Chitosan-Based Polymer Electrolytes with Various Salt Additives

Electrolyte and its components play a vital role on battery performance, as it is the interface at which all redox reactions responsible for working of a battery happen. Our study focuses on the use of Chitosan, a naturally available polysaccharide to form free-standing, flexible films that act as gel electrolytes. Chitosan was chosen among various polysaccharides for testing due to the ease of preparation from the shells of crabs, shrimps and prawns, natural abundance, renewability, biodegradability, cost-effectiveness, eco-friendly nature and a high degree of functionality which is not available in most synthetic polymers. During initial testing, the ionic conductivity value obtained for pristine chitosan was approximately 10-6S/cm, which is at least two orders of magnitude higher than the conventional synthetic polymers (PEO, PVP, etc.). This inherent advantage encouraged us to explore the possibility of their use as an electrolyte layer in batteries. It was noted that a semi-stable gel is formed when these biopolymers were vigorously mixed with minute amounts of acetic acid and dissolved in deionized water and allowed to sit for a while. It was also noted from the literature that chitosan films have an enormous surface area per unit volume (high aspect ratio), which makes us anticipate higher efficiencies. In our effort to make stable yet flexible organic films, various amounts of PVA (x=0.2, 0.4, 0.6, 0.8, 1) were added individually to Chitosan (CPx, CP=Chitosan: PVA), vortex mixed, cast into films, dried and then tested against SS blocking electrodes. Ionic conductivity studies on the various films provided a best average ionic conductivity value of 0.0068S/cm for CP0.2. This sample was then chosen and used for future experimentations due to enhanced conductivity from solvent retention of PVA and no rigidity induction in comparison to others.The CP0.2 samples were then soaked in varied concentrations (1, 2, 3, 4, 5, 6, 7 and 8M) of KOH, ZnCl2, and ZnSO4 for varied time intervals for swelling and pH studies. These studies were performed since previous literature indicated that the concentration of salt in which a polymer electrolyte is soaked affects its physical properties along with its cycling performance (reversibility and reactivity) in batteries. The CP0.2 samples were soaked in respective salt solutions (1-8M KOH/ ZnCl2/ ZnSO4) and measured for their weights for every 15 minutes for 1 hour and every hour for 6 hours. pH values of these varied electrolytes in salt solutions were measured simultaneously during experimentation. The pH values varied from 12-14, 6-2.5 and 5.5-3.5 for increasing concentration (1-8M) for samples in KOH, ZnCl2 and ZnSO4 respectively. The swelling coefficients (final weight/initial weight) were then calculated based on the values obtained. For all samples it was observed that the highest swelling coefficients were observed within 45 minutes of soaking, after which the swelling coefficients remained constant. The highest swelling coefficient of 2.1 was observed for CP0.2 soaked in 6M KOH for 45 minutes. Similarly, 1.97 for 1M ZnCl2 and 2 for 1M ZnSO4. These samples were also measured for ionic conductivities to assess their performance. The ionic conductivities of samples increased with soaking in higher concentrations of salt until 5M and then reduced beyond for KOH salt. A highest ionic conductivity of 0.916S/cm was recorded. The increased conductivity until 5M salt concentration may be due to increase in number of mobile ions (OH-) in the system generated from dissociation of additional KOH salt available. Beyond 5M, the decrease in ionic conductivities might be due to aggregation of excess ions causing reduction in mobility. It also may be due to salt crystallization observed, that greatly reduces the migration ability. For ZnCl2 and ZnSO4 samples the phenomenon of reduction in ionic conductivities were observed from the very beginning. The highest recorded ionic conductivities were 0.004913S/cm and 0.019183S/cm for samples in 1M ZnCl2 and ZnSO4 samples respectively. During experimentation it was observed that, the samples soaked in ZnCl2 were significantly turning brittle and non-flexible compared to other samples. We think this is due to salt crystallization in the sample and is confirmed by the lowest ionic conductivity values. When analyzing the pH and swelling studies in conjunction it was noted that maximum swellability of samples occurred at lower acidities for ZnCl2 (pH-6) and ZnSO4 (pH-5.5) solutions and at higher basicities for KOH (pH-13.5) solution. Also analyzing ionic conductivities together indicated that, higher swelling implied higher ionic conductivities. The best samples obtained with this study will further be tested in Zn-based batteries to access the effect and performance of the prepared varied pH alkaline and Zn ion salt-based electrolytes.

Determining the potential of 55 wt.% chitosan-45 wt.% NH4I biopolymer electrolyte for application in dye-sensitized solar cells

Solution casting technique has been used to prepared chitosan-based polymer electrolyte films. The polymer electrolyte (PE) film containing 55 wt.% of biopolymer chitosan, 45 wt.% of NH4I salt and 80 wt.% of 1-butyl-3-methylimidazolium iodide (BMII) displayed the highest room temperature ionic conductivity of 3.02 × 10−4 S cm−1. The interaction between components in the biopolymer electrolyte has been optically investigated. The configuration of indium tin-oxide (ITO)/TiO2/Ru-complex (N3) dye/biopolymer electrolyte/Pt/ITO dye-sensitized solar cells (DSSCs) were fabricated. DSSC with chitosan-based PE consist of 80 wt.% BMII exhibited the highest efficiency of 1.2%.

Performance of ZnO/ZnS nanocomposite based dye-sensitized solar cell with chitosan-polymer electrolyte

Chitosan is a biodegradable and nontoxic polymer and it exhibits piezoelectricity, which is a useful property for an electrolyte where the phototronic effect can be activated to enhance the power conversion efficiency (PCE) in solar cells. This is used here as an electrolyte in ZnO/ZnS based dye-sensitized solar cells (DSSCs). Also, to reduce the recombination of electrons, enhanced ionic conductivity and the stability of the redox this electrolyte is used. Here, ZnO/ZnS nanocomposite photo-anode is used in the fabrication of DSSCs and tested with LED lamp for the chitosan-based polymer electrolyte. The maximum PCE of 1.6% is achieved.

Investigation of plasticized ionic conductor based on chitosan and ammonium bromide for EDLC application

Abstract Chitosan-based polymer electrolytes incorporated with ammonium bromide (NH4Br) and glycerol were produced via solution casting technique. Characteristics of these electrolytes were examined using impedance technique, transport number measurement (TNM) and linear scan voltammetry (LSV). Based on the results obtained from impedance measurement, the sample with 40 wt.% glycerol achieved the highest ac and dc conductivies at room temperature. Dielectric behavior of the electrolytes was found to be improved upon incorporation of 40 wt.% glycerol, suggesting their relation with the conductivity trend. Result of TNM revealed that the conductivity has a huge contribution from ions. LSV analysis at 5 mV/s sweep rate showed that the best conducting sample is suitable for electrical double layer capacitor (EDLC) application. Specific capacitance (Cs) of the single carbon based electrode was determined from cyclic voltammetry (CV) technique.

Performance of chitosan based polymer electrolyte for natural dye sensitized solar cell

Out of the main challenge facing dye sensitized solar cells (DSSCs) is the leakage and vaporization of liquid electrolyte limiting the long term durability of these cells. Therefore, solidification of electrolyte in DSSCs is a crucial research direction. In this work, DSSC was assembled using electrolyte system composed of Chitosan as host polymer, ethylene carbonate as plasticizer, LiI: I2 as redox couple and TiO2 as filler; TiO2 modified with WO3 photoanode to provide inherent energy barrier and anthocyanin as sensitizer. The obtained solar cell conversion efficiency was about 1.8% with fill factor 53% using an irradiation of 100 mW/cm2 at 25 °C. The prepared DSSC is not only stable but also eco friendly due to use of natural polymer and dye. © 2018 American Institute of Chemical Engineers Environ Prog, 38: 630–634, 2019

Impedance Spectroscopy as a Novel Approach to Probe the Phase Transition and Microstructures Existing in CS:PEO Based Blend Electrolytes

In this work the role of phase transition of PEO from crystalline to amorphous phases on DC conductivity enhancement in chitosan-based polymer electrolyte was discussed. Silver ion-conducting polymer electrolytes based on chitosan (CS) incorporated with silver nitrate (AgNt) is prepared via solution cast technique. Various amounts of polyethylene oxide (PEO) are added to the CS:AgNt system to prepare blend polymer electrolytes. Ultraviolet-visible (UV-vis) spectrophotometry is used to confirm that the blended samples containing AgNt salt exhibit a broad absorption peak. From optical micrograph images it is apparent that small white specs appear on the surface of the samples. The SEM results clearly show the aggregated silver nanoparticles. The enlargement of the crystalline area was observed from the morphological emergence and impedance plots. The phase separation in SEM images was observed at high PEO concentration. The XRD consequences support the morphological manifestation. In this study a new approach is offered to explore the microstructures existing in the blend electrolytes. The width of the semicircle linked to crystalline phase in impedance spectra was found to be increased with the increase of PEO concentration. A slow increase of DC conductivity was observed at low temperatures while above 333 K an immediate change in DC conductivity was obtained. The rapid rise of DC conductivity at high temperatures is correlated with the DSC results and impedance studies at high temperatures.

Li+ doped chitosan-based solid polymer electrolyte incorporated with PEDOT:PSS for electrochromic device

In this study, solid polymer electrolyte (SPE) based on chitosan (Ch) was prepared with addition of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), lithium trifluro methane sulfonate (LiTRIF), propylene carbonate (PC) by solvent casting technique. The chitosan-based polymer electrolyte was characterized using electrochemical impedance spectroscopy (EIS). The ionic conductivity value was calculated as 4.2 x 10-4 S/cm. The SPE having good ionic conductivity was used to fabricate electrochromic device with glass/ITO/WO3׀PEDOT:PSS-Ch-LiTRIF-PC׀ITO/glass whose performance was evaluated via cyclic voltammetry, transmittance, repeating chronoamperometry. The optical contrast of ECD was attained as 22% at 800 nm, which resulting in coloration efficiency of 67 cm2/C. The ECD displays fast response time for coloration (tc ) is 0.29 s. Upon reversal of potential bleaching (tb ) forms within 3 s. The findings demonstrated that this SPE electrolyte has promising candidate for use in optoelectronic applications.

Fabrications and investigation of physicochemical and electrochemical properties of heteropoly acid-doped sulfonated chitosan-based polymer electrolyte membranes for fuel cell applications

A proton exchange membrane for fuel cell application consists of modified chitosan/PEO doped with different weight percentage of HPA acids cross-linked by sulfosuccinic acid. Modifying the chemical structure of the chitosan by means of sulfonation, which was successfully synthesized by direct sulfonating reagent 1,3-propane sultone, chemical structure and thermal stability of the membrane were characterized by FTIR and TG analysis. Further the membrane was characterized by XRD, SEM, AFM and impedance analysis. The results shows that the structure of the composite membranes becomes more compact compared with undoped membranes due to interaction between the sulfonic acid groups and amine groups. This could lead to increase the conductivity and reduce the excess swelling of the membrane. From all the results, these biodegradable and low-costs composite membrane was tested in the single-cell proton exchange membrane fuel cell and it predicts that chitosan-based electrolytes are promising material for fuel cell application.

Effect of Modified Natural Filler O-Methylene Phosphonic κ-Carrageenan on Chitosan-Based Polymer Electrolytes

The potential for using O-methylene phosphonic κ-carrageenan (OMPk) as a filler in the chitosan-based polymer electrolyte N-methylene phosphonic chitosan (NMPC) was investigated. OMPk, a derivative of κ-carrageenan, was synthesized via phosphorylation and characterized using infrared spectroscopy (IR) and nuclear magnetic resonance (NMR). Both the IR and NMR results confirmed the phosphorylation of the parent carrageenan. The solid polymer electrolyte (SPE)-based NMPC was prepared by solution casting with different weight percentages of OMPk ranging from 2 to 8 wt %. The tensile strength of the polymer membrane increased from 18.02 to 38.95 MPa as the amount of OMPk increased to 6 wt %. However, the increase in the ionic conductivity did not match the increase in the tensile strength. The highest ionic conductivity was achieved with 4 wt % OMPk, which resulted in 1.43 × 10−5 Scm−1. The κ-carrageenan-based OMPk filler strengthened the SPE while maintaining an acceptable level of ionic conductivity.

Ionic Conductivity of Chitosan-based Polymer Electrolyte with Polyethylene Glycol (PEG) as Plasticizer and KCl as Alkaline Ion Transport Source

Polymer electrolyte films were fabricated utilizing chitosan biopolymer plasticized with polyethylene glycol (PEG) and KCl addition as ionic transport source. The precursor solution was prepared by mixing the chitosan in acetic acid solution and PEG that act as a plasticizer. Into the mixed solution was added KCl salt for as alkalin ion transport source in the polymer electrolyte. The polymer electrolyte films were fabricated by the casting method onto the petri glass. The influence of KCl content on ionic conductivity of the composite polymer electrolyte film was studied. The ionic conductivity of the composite polymer electrolyte film was characterized using LCR meter at a frequency of 1 kHz. The best ionic conductivity was found for the film containing 45 wt% of KCl salt. The activation energy was determined by using Arrhenius plot based on conductivity data at varied temperature. It has been found that the activation energy of the composite polymer electrolyte films varied to the KCL content in the composite polymer electrolyte films. The highest activation energy was found for the polymer electrolyte film with 45 wt% of KCl content.

The Mixed Contribution of Ionic and Electronic Carriers to Conductivity in Chitosan Based Solid Electrolytes Mediated by CuNt Salt

This work shows the contribution of both ionic and electronic conductivities in chitosan (CS) based solid polymer electrolytes incorporated with various amounts of copper nitrate (CuNt). The samples were prepared using solution cast technique. The second semicircles at intermediate frequency in impedance plots were observed. Surface plasmonic resonance (SPR) was illustrated from the UV–Vis spectrophotometry, where broad peaks at 702 nm were obtained as an evidence for nanoparticles formation. The second semicircles in the impedance plots and the distinguished SPR peaks have revealed the contribution of electronic conductivity in CS:CuNt based polymer electrolytes. The same trend of UV–Vis spectra at different temperatures reveals that CS:CuNt polymer electrolyte is thermally stable. The presence of electronic conductivity is the main shortcoming of copper ion conducting solid polymer electrolytes. The role of lattice energy of the copper salts on electrical properties and morphological (SEM) appearance was discussed. The TEM image shows Cu nanopartciles with various sizes. A stable SPR peak and vanishing of second semicircle at high temperatures reveals the stability of copper ion conducting chitosan based polymer electrolytes. The pattern of DC conductivity and dielectric constant as a function of salt concentration are almost found to be similar. Both estimated DC conductivities from AC spectra and those calculated from impedance plots are shown to be comparable. Highest DC conductivity of 3.65 × 10−5 S/cm has been achieved for the sample incorporated with 21 wt% of CuNt. The high value of dielectric constant at low frequency can be ascribed to electrode polarization. Electric modulus parameters are studied to understand the relaxation process. Two semicircles in Argand plots were separated.