FWF I4383N: Proton transfer in protic ionic liquids
grant holder
Christian Schröder
funding period
10/2020 - 09/2023
Abstract
Non-flammable ionic liquids are promising candidates for future battery generations. Using ionic liquids
could avoid the use of Critical Raw Materials in battery manufacturing process, which in the case of currently
used lithium batteries imply uncertainty about a safe supply of these materials at a competitive cost.
Ionic liquids could also solve issues with flammability of currently used electrolytes.
The high viscosity of ‘conventional’ ionic liquids, however, leads to rather low electric conductivities.
This drawback for many applications can be circumvented by using protic ionic liquids.
The key property that distinguishes this subclass from other ionic liquids is the reversible proton transfer
from an acid (proton donor) to a base (proton acceptor). Charge transport can thus be decoupled from mass transport
and the low proton mass can make charges very mobile, i.e. increases the conductivity.
So far, the ionic mobility and distribution of charge carriers has been widely assessed either from the average,
equilibrium distribution of protons as obtained from molecular spectroscopies, or from the long-ranged transport
of all charge carriers as measured via the electrolyte conductivity. Both experiments allow to classify the “ionicity”,
which however led to unsatisfactory and inconsistent results.
Non-flammable ionic liquids are promising candidates for future battery generations. Using ionic liquids
could avoid the use of Critical Raw Materials in battery manufacturing process, which in the case of currently
used lithium batteries imply uncertainty about a safe supply of these materials at a competitive cost.
Ionic liquids could also solve issues with flammability of currently used electrolytes.
The high viscosity of ‘conventional’ ionic liquids, however, leads to rather low electric conductivities.
This drawback for many applications can be circumvented by using protic ionic liquids.
The key property that distinguishes this subclass from other ionic liquids is the reversible proton transfer
from an acid (proton donor) to a base (proton acceptor). Charge transport can thus be decoupled from mass transport
and the low proton mass can make charges very mobile, i.e. increases the conductivity.
So far, the ionic mobility and distribution of charge carriers has been widely assessed either from the average,
equilibrium distribution of protons as obtained from molecular spectroscopies, or from the long-ranged transport
of all charge carriers as measured via the electrolyte conductivity. Both experiments allow to classify the “ionicity”,
which however led to unsatisfactory and inconsistent results.