Internal fields in solid electrolytes due to interface effects

The space charge distribution and therefore the distribution of the internal potential in ion-conducting polymers can strongly be influenced by electrode effects. Due to image forces the electrodes attract mobile ions to the electrolyte/electrode interface. Simulations performed with a three-dimensional hopping model yield a charge accumulation of mobile ions at the electrodes as well as a depletion zone near this accumulation layer even without external applied field. The resulting potential shows a maximum in the middle of the sample. Measurements of the surface potential performed with a scanning Kelvin probe using polyethylene oxide confirm the model.