Synthesis of the nanocomposite polymeric electrolyte in the form of a hyperbranched network as a result of reaction of metaloorganic precursor and olygoethers

aim of project The aim of the work is related to the synthesis of the new class of polymeric electrolytes. Obtained systems will be based on the nanocomposite matrix. It is assumed that nanosized fi ller will be obtained by the in-situ hydrolysis reaction of the organometallic precursor with the use of water residues present in the system (polymer + salt). The metaloorganic precursor used belongs to the so-called methylalumoxanes class of compounds (MAO). Additionally, MAO molecule can react with the polymeric matrix of the general chemical formula: CH3O- -(CH2CH2O)n-CH2CH 2OH creating compounds belonging to aluminum alcoxylates (olygoglycolates in this case). Due to the fact that one MAO molecule comprises more than ten –CH3 moieties able to react in both above mentioned ways, it is possible to fi nally produce branched structures with a centre of an MAO core. The next strategy is related to the possibility of incorporation into the obtained structure molecules of the olygoxyethylene glycol containing two free –OH moieties (HO-(CH2CH2O)m - CH2CH2OH). This mixture of substrates leads to the synthesis of the partially cross-linked structure as two functional monomers can react with MAO molecules. Finally, by changing the proportion between the glycols used and by tailoring their molecular mass (and in consequence the length of the chain) it is possible to control the rheological properties of the obtained matrices together with their lithium cation transport properties. The electrolyte obtained in gel form is easily processable and can be applied directly on the surface of the electrodes (the substrate components are liquid). The gelifi cation process is conducted solvent free and in ambient conditions.

Expected results
One of the methods leading to the improvement of the polymeric electrolyte properties is based on obtaining polymer-ceramic composites containing the dispersed non-conductive phase able to change the crystalline structure of the polymeric matrix. In consequence, the improvement of the electric conductivity of the system is achieved. Additionally, such systems are characterized with improved mechanical properties and better electrochemical stability. The last feature is assigned to the trapping of the polymer matrix impurities by their adsorption on the grain surface. In consequence, growth of the passive layer on the electrode surface is depleted. Additionally, fi ller grains mechanically block dendrite formation. Both electric and electrochemical eff ects of grain addition increase with the decrease of the addend grain size. Large scale synthesis of the nanocomposite system is diffi cult because of the grain aggregation eff ect. In the proposed synthetic route of the nanocomposite matrix, a bifunctional metaloorganic precursor of the inorganic fi ller is utilized. In consequence, the aggregation problem is generally solved as fi ller particles are created in-situ in a reaction of the precursor with residual water present in the system. It leads to the inhibition of the aggregation process by the viscous medium of a polymeric matrix. Additionally, the impurities present in the system, which are responsible for the electrode passivation process, are bounded by the precursor not only by the adsorption process but also through a chemical reaction, so in a much stronger and irreversible manner.

The obtained material can be thus utilized in a reversible lithium- polymer battery incorporating an anode formed from metallic lithium.