Kuldeep Mishra

Studies on a proton battery using gel polymer electrolyte

A proton-conducting film of gel polymer electrolyte, poly(vinylidene fluoride hexafluoropropylene)/poly(methyl methacrylate) + ammonium thiocyanate + ethylene carbonate + propylene carbonate, has been prepared by solution casting technique. The ionic conductivity of the film is in the order of approximately 10−3 S cm− 1 at room temperature. A proton battery with the configuration zinc + zinc sulfate heptahydrate | gel electrolyte | lead oxide + vanadium pentoxide has been fabricated using this film as electrolyte and separator between the electrodes. The battery shows an open circuit voltage of 1.45 V and energy density of approximately 10 Wh kg−1at low current drain. The rechargeability of the battery has been observed up to three cycles after which its discharge capacity starts fading.

Investigations on Poly(ethylene oxide) + NH4PF6 Solid Polymer Electrolyte System

The authors report experimental investigation on a solid polymer electrolyte PEO + NH4PF6. The solid thin films of different compositions of PEO + NH4PF6 complex were synthesized using solution cast technique and characterized. Complexation between polymer and the salt has been established using X-ray diffraction, Fourier transform infrared spectroscopy, differential thermal analysis, and thermogravimetric analysis. Ion transport in the polymer material has been studied by electrical conductivity measurements with composition, temperature, and humidity; by total ionic transference number measurement; and by dielectric measurements. The maximum room temperature (∼29°C) conductivity of the material has been found to be 1.04 × 10−6 S cm−1 for at RH = 60%. The conductivity shows strong humidity dependence. The temperature dependence of the conductivity shows the Arrhenius behavior. The total ionic transference number of the electrolyte material has been found to be between 0.94 and 0.97.

Studies on PEO-BMImHSO4 solid polymer electrolyte

Polymer electrolyte membrane based on Polyethylene oxide/1-Butyl-3-methylimidazolium hydrogen sulfate (PEO-BMImHSO4) is prepared. The highest room temperature ionic conductivity of the membrane is obtained as ∼ 4.27 × 10−5 Scm−1. Ion dynamics is studied using dielectric measurements which reveal translational motion of the ions in the prepared polymer electrolyte. The loss tangent (tan δ) reflects faster ion hoping in the electrolyte but at higher concentration of IL, hoping rate receives tapering.

All-solid-state proton battery using gel polymer electrolyte

A proton conducting gel polymer electrolyte system; PMMA+NH4SCN+EC/PC, has been prepared. The highest ionic conductivity obtained from the system is 2.5 × 10−4 S cm−1. The optimized composition of the gel electrolyte has been used to fabricate a proton battery with Zn/ZnSO4⋅7H2O anode and MnO2 cathode. The open circuit voltage of the battery is 1.4 V and the highest energy density is 5.7 W h kg−1 for low current drain.

Nanofiller-incorporated porous polymer electrolyte for electrochemical energy storage devices

We report the poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP)-based microporous polymer membranes, prepared by phase inversion technique, incorporated with different amounts of nanosized zirconium dioxide (ZrO2) filler. Scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and thermal studies confirm the role of ZrO2 nanofiller to modify the polymer structure, pore geometry and crystallinity. The nanofillers interact with the PVdF-HFP chains via surface groups and electrostatic interactions, and their incorporation led to an increase in crystalline content of the membrane and ionic conductivity (when activated with a liquid electrolyte (LE)). A possible mechanism for the increase in crystallinity in the polymer due to interaction with nanofiller particles has also been presented. The optimized membrane has been saturated with an LE sodium perchlorate-ethylene carbonate:propylene carbonate for use as a separator/electrolyte in electrical double-layer capacitor (EDLC). The cells fabricated with the nanofiller-incorporated membrane show better performance in terms of specific electrode capacitance, specific energy and specific power (approximately 76 F g−1, approximately 20.9 Wh kg−1 and 2.62 kW kg−1) than the cells using the membrane devoid of nanofillers (approximately 61 F g−1, approximately 17.3 Wh kg−1 and approximately 3.16 kW kg−1), respectively. The EDLC shows approximately 85% retention in specific capacitance for 10,000 charge–discharge cycles.

Effect of Plasticizers on Ion Transport Properties of PEO+NH4PF6 Polymer Electrolyte System – Dielectric Studies

Dielectric properties of proton conducting polymer electrolyte system, containing polyethylene oxide (PEO) as host polymer and ammonium hexfluorophosphate (NH4PF6) as complexing salt plasticized with EC and EC:PC, are investigated. The free standing films of thickness ~ 200 - 300µm are synthesized by solution casting technique. The electrical conductivity studies show that plasticization of the polymer electrolyte results into an enhancement in its conductivity by about two orders of magnitude. The maximum room temperature bulk conductivity is obtained to be ~ 10-5 S/cm for the plasticized polymer electrolyte. To understand the ion transport mechanism, different frequency dependent parameters are measured like dielectric permittivity, loss tangent and AC conductivity. The ionic transference number of the prepared systems is found to be close to unity which shows ion dominant charge transport in the electrolyte system. The conductivity of the polymer electrolyte has been found to be very sensitive to the relative humidity, which makes it a good candidate for its application for humidity sensor.