Sustainable and Printable Nanocellulose-Based Ionogels as Gel Polymer Electrolytes for Supercapacitors

A new gel polymer electrolyte (GPE) based supercapacitor with an ionic conductivity up to 0.32–0.94 mS cm−2 has been synthesized from a mixture of an ionic liquid (IL) with nanocellulose (NC). The new NC-ionogel was prepared by combining the IL 1-ethyl-3-methylimidazolium dimethyl phosphate (EMIMP) with carboxymethylated cellulose nanofibers (CNFc) at different ratios (CNFc ratio from 1 to 4). The addition of CNFc improved the ionogel properties to become easily printable onto the electrode surface. The new GPE based supercapacitor cell showed good electrochemical performance with specific capacitance of 160 F g−1 and an equivalent series resistance (ESR) of 10.2 Ω cm−2 at a current density of 1 mA cm−2. The accessibility to the full capacitance of the device is demonstrated after the addition of CNFc in EMIMP compared to the pristine EMIMP (99 F g−1 and 14.7 Ω cm−2).

Influence of Nano Filler (ZrO2) on Optical and Thermal Studies of Potassium Doped Polyethylene Oxide Solid Polymer Electrolytes

Solid polymer electrolyte films made with potassium doped Polyethylene oxide using ZrO2 as nanofiller (70PEO-30KBF4-x ZrO2 where x = 1, 2.5, 5, 7.5, & 10 wt% ­­) were prepared by solution casting technique. Optical and thermal properties of polymer electrolyte films were studied by using Optical absorption and DSC techniques. From Optical absorption spectra, it is observed that fundamental absorption edge is shifted towards the higher wavelength side (range 259- 297 nm) with increase of nano filler (ZrO­2) concentration (1-10 wt %). Optical band gap for all electronic transitions (p=1/2, 2, 2/3 and 1/3) are found to be increased as incorporation of nano filler (ZrO2) which confirms the structural rearrangements takes place in polymer electrolyte films. Optical band gap for indirect allowed transitions (p=1/2) are found to be in the range of 1.93-3.34eV. Decrease in Urbach energy (4.8eV- 1.4eV) is associated with decrease in defect formation in host polymeric matrix (PEO-KBF4) as a result of embedded nano filler (ZrO2). DSC spectra analysis of polymer electrolytes has showed melting temperatures in the range 63.63-73.71°C and highest crystallinity is found to be 85 % (10 wt % ZrO­2). Enthalpy values are elevated with increase in nanofiller composition (ZrO2) in the present polymer electrolyte films.Keywords: PEO based polymer electrolytes, Solid polymer electrolytes, Optical and Thermal studies.