Combining 3D Printing and promising Electrolyte Research: Ionic Liquid based Membrane Materials
Alyna LANGE1, Kerstin ZEHBE1, Khalid ELAMIN2, Iqbaal ABDURROKHMAN2, Zaneta WOJNAROWSKA3, Marian PALUCH3, Andreas TAUBERT1
1University of Potsdam, Potsdam, Germany
2Chalmers University of Technology, Gothenburg, Sweden
3University of Silesia in Katowice, Chorzow, Poland
As promising components in energy devices such as fuel or solar cells and batteries ionic liquids (ILs) are discussed due to their favorable properties. These salts with melting points below 100 °C show e.g., high thermal and electrochemical stability, high ionic conductivities and non-flammability, making them interesting candidates for use as electrolytes.[1,2]
One of the most pressing global issues of our time, when disregarding the current COVID19 crisis, is the climate change with its well-known challenges concerning the climate policy and the energy economy. In light of recent developments, a lot of research is being done in the fields of fuel cells and batteries and their improvements, as these technologies are not without some disadvantages themselves, especially concerning safety and leakage issues for batteries and low efficiency and necessity for high purity hydrogen for fuel cells. Most polymer-electrolyte-membrane (PEM) fuel cells for example work with Nafion® as their membrane. Nafion®, a fluorinated copolymer, however loses conductivity at higher temperatures due to dehydration, limiting its operation temperature to around 80 °C at ambient pressure.[1] ILs are considered compounds that can overcome these limitations as they offer high conductivities even at elevated temperatures.
For the applications as electrolytes in the aforementioned systems the immobilization of the ILs is necessary, however, to prevent leaking and realize proper function.[2,3] The resulting ionogels (IGs) then combine the properties of the polymer matrix, i.e. its mechanical stability, with the characteristics of the respective IL. A suitable method to realize precise geometries and shapes for these membranes is given by 3D printing, which offers adaptable electrolyte design.[4]
The aim of this work is the synthesis and characterization of ILs for ion (specifically proton) conduction. The ILs exhibit wide electrochemical and thermal stability windows and their ionic conductivities range between 10?2 ? 10?4 S/cm at elevated temperatures. They are furthermore investigated under aspects of ion and proton transport via different spectroscopy methods.[4,5] Moreover, the ILs are immobilized in different polymer matrix materials to provide flexible and transparent IGs that contain up to 80 wt% of IL and show promising electrolyte properties after addition of the ILs. Successful 3D-printing and structuring of the IGs is also demonstrated.[4]
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