Biopolymer Kappa Carrageenan with Ammonium Chloride as Electrolyte for Potential Application in Organic Battery

Carrageenan is a generic name for a family of natural, water-soluble, sulphated galactans isolated from red seaweeds and exploited commercially. The biopolymer of kappa carrageenan has been known to be used as electrolyte in electrochemical device since it shows good ionic conductivity characteristic. In this study, we attempt to study the chemical, morphology, and electric properties of biopolymer kappa carrageenan. We developed a free-standing film of kappa carrageenan with addition of ammonium chloride as an electrolyte for an organic battery prototype. We prepared the solution by mixing kappa carrageenan, ammonium chloride and water to form a gel with a particular concentration. Then, the gel was coated on the substrate and cured at 50°C for 4 hours. The final free-standing film product reveals a thickness about 100-200 mm as captured by SEM image in cross-section view. The morphology of kappa carrageenan with or without ammonium chloride clearly shows a non-homogeneous surface that attributed to the nature characteristics of kappa carrageenan immiscible. The addition of ammonium chloride into kappa carrageenan forms a smoother surface that show good mixture of kappa carrageenan. FTIR spectra of the samples show the interaction of ammonium chloride to the host polymer of kappa carrageenan as indicated by the shifted of the O-H peak from 3448 to 3446 cm-1 and from 3288 to 3207 cm-1 while the peak of 2924 cm-1 is disappeared after addition of the ammonium chloride. The implementation of this film in an organic C_Zn battery prototype shows that battery’s voltage reached 2.1 Volt by charging. Then, the battery can be used to emit an LED with 20 µA electrical current for about 1 hour in discharging process.