Title : New fluorine containing solid polymer electrolyte membranes
Abstract:
Polymer electrolytes (PE) play an important role in electrochemical devices such as batteries and fuel cells. To achieve optimal performance, the PE must maintain a high ionic conductivity and mechanical stability at both high and low relative humidity. The polymer electrolyte also needs to have excellent chemical stability for long product life and robustness.
According to the prevailing theory, ionic conduction in polymer electrolytes is facilitated by the large-scale segmental motion of the polymer backbone and primarily occurs in the amorphous regions of the polymer electrolyte. Crystallinity restricts polymer backbone segmental motion and significantly reduces conductivity. Consequently, polymer electrolytes with high conductivity at room temperature have been sought through polymers which have highly flexible backbones and have largely amorphous morphology.
The interest to polymer electrolyte was increased also by potential applications of solid polymer electrolytes in high energy density solid state batteries, gas sensors and electrochromic windows. Conductivity of 10-3 S/cm is commonly regarded as a necessary minimum value for practical applications in batteries. It is well established also that lithium ion coordination takes place predomi-nantly in the amorphous domain and that the segmental mobility of the polymer is an important factor in determining the ionic mobility important. So, investigation in the field of creation new solid polymer electrolyte membranes with new host fluorine groups is important.
By hydrosilylation reaction of 2.4.6.8-tetrahydro-2.4.6.8-tetramethylcyclotetrasiloxane (D4 H) with 2.2.3.3.4.4.5.5.6.6-octafluoropentyl acrylate and vinyltriethoxysilane at 1:3:1 ratio of initial compounds in the presence of platinum catalysts D4 RR’type adduct has been obtained. Via ring opening polymerization reaction of D4 R,R’ in solution, in the presence of anhydrous powder-like potassium hydroxide, new comb-type siloxane matrixes with pendant octafluoropentyl propionate side groups and triethoxysilane groups have been obtained. So, ssynthesized comb-type polymers were analyzed by FTIR, 1 H, 13C, and 29Si NMR spectroscopy, DSC and GPC methods. Sol-gel reactions of polymers doped with lithium trifluoromethanesulfonate (triflate) and lithium bis (trifluoromethanelsulfonyl)imide have been studied and new solid polymer electrolyte membranes have been obtained. The ion conductivity of the membranes was determined via electrical impedance spectroscopy. The ion conductivity of solid polymer electrolyte membranes at 25o C changes in the range 7.8x10-5 - 9.1x10-7 S/cm.
Acknowledgment: The financial support of the Georgian National Science Foundation and Technology Centre in
Ukraine, STCU-2016-16 (6301), is gratefully acknowledged.
Audience take away:
- Synthesis of new D4 ’ type organocyclotetrasiloxanes containing 2.2.3.3.4.4.5.5.6.6-octafluoropentyl propionate groups and ethyltriethoxysilane crosslinking moieties at silicon; investigation polymerization reactions of organocyclotetrasiloxanes in the presence of various catalysts; investigation of sol-gel reactions of obtained combtype polymers with regular arrangement of side groups; obtaining solid polymer electrolyte membranes on the base of Lithium salt: Lithium triflate and Lithium bis(trifluoromethanesulfonyl) imide and investigation of their ion-conductivity.
- For obtaining of comb-type polymers with regular arrangement of electro donor side groups they will use suggested by us this method.
- This suggested way of synthesis of comb-type polymers with regular structure for obtaining of solid PE membranes will be used by another researcher in their research and teaching, which will be make their research more efficient, informative and interesting.
