Imidazolium ionic liquids as electrolytes for manganese dioxide free Leclanche batteries

A set of four imidazolium ionic liquids (solid at room temperature) and one imidazolium ionic solid was screened for its potential as electrolytes in manganese dioxide free Leclanche batteries, equipped with a zinc anode and graphite cathode. Electrical impedance spectroscopy allowed to determine the room-temperature ionic solids (RTISs) ionic conductivities, which was the highest for carboxylic acid functionalized RTIS 3 [C(2)O(2)Mlm][CI]. The toxic manganese dioxide was substituted by benzoquinone. A systematic ionic conductivity optimization of RTIS 3-benzoquinone-ZnSO4-H2O mixtures at room temperature resulted in the identification of the following conditions for the Leclanche battery studies: 50 mg of a 50:50 RTIS:benzoquinone mixture and 96 mg of water. The chronopotentiometric experiments with a constant current of 5 M showed a remarkable performance for the RTIS 3 based battery. The potential (1.47 V) and stability is comparable to that of the commercial Rayovac (R) battery filling (model AA). Furthermore, linear potentiodynamic voltammetry (0.01 V/s) and chronoamperometric analysis at short-circuit conditions (0.0 V) validated the RTIS 3-benzoquinone-water battery as a promising alternative for manganese dioxide free Leclanche batteries. (C) 2008 Elsevier Ltd. All rights reserved.