Influence of Water on Poly(propylene glycol)- Lithium Triflate Electrolytes, Studied by Impedance and Infrared Spectroscopy
Typ
Examensarbete för masterexamen
Program
Physics and astronomy (MPPAS), MSc
Publicerad
2019
Författare
Olander, Erik
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
In this thesis, Poly(propylene glycol)4000-LiCF3SO3-water electrolytes were
studied with thermogravimetry, impedance and infrared spectroscopy. A method for drying the
compounds and adding water was developed success- fully. Among the samples without water, the
medium concentration 0.63 mol/kg LiCF3SO3 (LiTf) had the highest conductivity of 2.9 10−4 S/m.
Water increased the conductivity for all samples. The conductivity increased the most for the high
concentration 2.7 mol/kg LiTf sample, from 8.4 10−6 S/m dry to 1.5 10−2 S/m wet. Water in PPG4000
above saturation sepa- rates into a wet polymer phase and an aqueous phase, but LiTf enables more
water to be mixed into the electrolyte without phase separation. The limited molecular interaction
between PPG4000 chain and water explains the phase separation. The PPG4000 hydrophilic OH endgroups
can explain the ability to form emulsion with water. The SO3 1041 cm−1 and 1031 cm−1 symmetric
stretch IR bands show that OH and Li+ compete in interacting with SO3.
The ion pair dissociation could explain part of the conductivity increase with added water.
Beskrivning
Ämne/nyckelord
Polymer electrolytes , Impedance Spectroscopy , Conductivity , Permittivity , FTIR Infrared Spectroscopy , Lithium Triflate LiCF3SO3 , Poly(propylene glycol) PPG PPG4000 , Poly(propylene glycol)-Water Mixtures , Poly(propylene glycol)-Lithium Triflate electrolytes , Poly(propylene glycol)-Lithium Triflate-Water Mixtures , Macrophase and Microphase Separation , Phase Separation , Ion Pairs , Aqueous electrolytes