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Eco-friendly gel polymer electrolytes (GPEs) for energy storage systems with high ionic conductivities


Kurzfassung

Gel polymer electrolytes (GPEs) have advantageous properties in case of leakage or exposure to higher temperatures when compared to conventional fluid electrolytes. Unfortunately, in case such an energy storage system catches fire, the polymer matrix of the usual gel polymer electrolyte may decompose, resulting in a release of highly toxic hydrogen fluoride. Evan more important, the ionic conductivity of gel polymer electrolytes based on highly fluorinated polymers is in many cases significantly less than that of the underlying fluid electrolyte. Here we present novel freestanding gel polymer electrolytes based on a polyhydroxyurethane matrix which show even higher ionic conductivities compared to usual GPEs reported in the art. In addition, the novel gel polymer electrolytes are eco-friendly. They are free of fluorine and can be produced from bio-based starting materials or biological/renewable (re)sources such as carbohydrates and proteins. The internal resistance being composed of the reaction resistance and the electrical resistance of the GPE-based cell, was significant lower compared to the internal resistance of a reference cell. In particular, ionic conductivities of the novel gel polymer electrolytes, as measured by electrochemical impedance spectroscopy, were up to 20 times higher compared to conventional systems.


Hintergrund

Gel polymer electrolytes (GPEs) are used in energy storages systems like chargeable and non-chargeable batteries, capacitors, fuel cells, and dye-sensitized solar cells. Gel polymer electrolytes (GPEs) have advantageous properties in case of leakage or exposure to higher temperatures when compared to conventional fluid electrolytes.


Problemstellung

Gel polymer electrolytes (GPEs) are usually produced from highly fluorinated polymers, such as polyvinylidene difluoride (PVdF). This leads to some drawbacks. Fluorine is a corrosive and toxic gas, therefore requires elaborated safety standards which results in increased manufacturing costs associated with the final energy storage system. Furthermore, in case such an energy storage system catches fire, the polymer matrix of the usual gel polymer electrolyte may decompose, resulting in a release of highly toxic hydrogen fluoride.
Even more important, the ionic conductivity of gel polymer electrolytes based on highly fluorinated polymers is in many cases significantly less than that of the underlying fluid electrolyte.


Lösung

In a project funded by Baden-Württemberg Stiftung gGmbH scientists at the University of Freiburg have developed an energy storage system comprising Polyhydroxyurethane-based gel polymer electrolytes. The internal resistance being composed of the reaction resistance and the electrical resistance of the GPE-based cell, was significant lower compared to the internal resistance of a reference cell. In particular, ionic conductivities of the novel gel polymer electrolytes, as measured by electrochemical impedance spectroscopy, were up to 20 times higher compared to conventional systems.


Vorteile

  • ionic conductivity up to 20 times higher compared to conventional systems
  • further increase of ionic conductivity by use of conductive fillers, such as graphene or graphene oxide
  • novel gel polymer electrolytes (GPEs) based on a polyhydroxyurethane matrix
  • eco-friendly i.e., free of fluorine and can be produced from bio-based starting materials or biological/renewable (re)sources
  • GPE-based cells successfully tested by running 150 charging and discharging cycles with excellent capacity retention
  • works in sodium ion batteries or lithium ion batteries

Anwendungsbereiche

Here we present novel freestanding gel polymer electrolytes based on a polyhydroxyurethane matrix which show even higher ionic conductivities compared to usual GPEs reported in the art. In addition, the novel gel polymer electrolytes are eco-friendly. They are free of fluorine and can be produced from bio-based starting materials or biological/renewable (re)sources such as carbohydrates and proteins.


Service

Technologie-Lizenz-Büro GmbH is responsible for the exploitation of this technology and assists companies in obtaining licenses.


Technologie-Lizenz-Büro (TLB) der Baden-Württembergischen Hochschulen GmbH

Dr. Frank Schlotter
+ 49 721 790 040
fschlotter@tlb.de
www.tlb.de
Adresse
Ettlinger Straße 25
76137 Karlsruhe



Entwicklungsstand

Demonstrationsexemplar


Patentsituation

  • EP anhängig

Stichworte

crosslinked, gel polymer electrolyte, biobased, ionic conductivity, sodium ion battery

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