Nonaqueous Protonic Electrolytes Based on Methacrylic Monomers and Their Application in Supercapacitors

INTRODUCTION

The growing interest in proton conducting solid systems can be easily explain by their superior conductivities, which are related to the unique property of proton, the absence of the electron shell and by this higher mobility. Compared to other solid proton conductor polymer electrolytes have several advantages, such as processibility and flexibility of polymer matrix, enabling the contact with the electrode surface. those properties made them attractive for a possible application in chemical sensors [1], electrochromic devices [2], fuel cells [3] or supercapacitors [4,5].

In this work we present study of methacrylate copolymer gel electrolyte. This is followed by a application of so prepared membrane for supercapacitor with electrodes made of activated carbons.

EXPERIMENTAL

Protonic gel samples were prepared in small glass containers by dissolving proton donor in organic solvent. This was follow by the addition of monomers, benzoyl peroxide and TEGDM and the mixing of the entire solution over 1h to obtain homogeneity. After this time the solution was cast as a thin film and placed in oven at 60-70°C for 12h to allow for gelation. All the steps took placed in the glovebox with inert atmosphere of Argon gas, and with oxygen and water content of less than 1 ppm. The electrolyte was composed of different proton  content, 12,5% polymer matrix (different monomers ratio) and solvent. In the respect of polymer amount it was added 1% of BP and 5% of TEGDM.

The active electrodes were prepared by mixing carbon with 5% of PTFE. So prepared paste was cut into electrodes with surface area ~0,79cm²and thickness was kept in the range 200-250µm. Then placed in vacuum oven and dried at 120°C.

The symmetrical capacitors were assembled in two electrode cell Swagelok^®. The carbon electrodes were placed on a gold current collector (thickness ~60µm) and they were separated with our electrolyte.

CONCLUSIONS

Prepared electrolytes are elastic and transparent membranes. Their characterization focused on conductivity and electrochemical stability measurements, DSC and FTIR characterization. It helped in describing proton conductive mechanism.

The preliminary results obtained for the supercapacitor with Multiwalled Carbon Nanotubes as electrodes and 40% w/w H₃PO₄ (proton donor), HEMA-co-MMA (polymer matrix), propylene carbonate (solvent) as electrolyte show capacitance close to 11F/g. This value is typical for MWCNT material. The obtained results were compared to the value obtained for supercapacitor with liquid 40% H₃PO₄in PC used as electrolyte. The detailed results will be presented and discussed during the talk

ACKNOWLEDGMENT

The MPD/2010/4 project is realized within the MPD programme of Foundation for Polish Science, cofinanced from European Union, Regional Development Fund.

REFERENCES

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5. H. Gao, K. Lian, J. Power Sources, 196 (2011) 8855-8857