Bioderived Ionic Liquids with Alkaline Metal Ions for Biodegradable Electrochemical Devices

An ionic liquid, choline lactate, composed of bioderived materials offers an opportunity to develop electrochemical devices which degrade after use. Although ionic liquids show large potential window, high ionic conductivity, and non-volatility, the ionic liquids do not show electrochemical characteristics – intercalation pseudo-capacitance, redox pseudo-capacitance, electrochromism, for example. We, therefore, develop bioderived ionic liquids including biodegradable metal ions, Li, Na, and Ca, to yield the ionic liquids the electrochemical behaviors. Differential scanning calorimetry reveals that the ionic liquids remain liquid states with a temperature range from 230.42 K to 373.15K. The ionic liquids with metal ions show lower ionic conductivities than that of the pristine ionic liquid whereas influence of the ions on capacitances are negligibly small. A biodegradability test based on a protocol of Organization for Economic Co-operation and Development 301C modified MITI test (I) confirms that the pristine ionic liquid and an ionic gel composed of the ionic liquid and poly(vinyl alcohol) exhibit ready biodegradability and biodegradability, respectively. The results are of interest as the biodegradable ionic liquids with metal ions for electrochemical devices in research fields including environmentally benign devices, sustainable electronics, and bioresorbable/implantable devices, that conventional ionic liquids are unable to achieve.