Nano scale electrochemistry: Application to solid electrolytes

Electrochemistry underlies a variety of useful applications such as batteries, fuel cells, and ionic sensors. However, these applications are currently facing numerous problems and challenges such as low power/energy density, short running time, low efficiency, vulnerability to contamination and costliness. The rate of improvement has recently decreased because the fundamental scientific understanding for each electrochemical phenomenon is limited.;For the fundamental understanding of physics behind the observed bulk phenomena, direct nano-scale observation should be of great help. In the last few decades, a variety of scanning probe based nano-scale electrical/electrochemical measurement schemes has been developed.;The first part of this thesis presents a newly proposed method to obtain AC impedance maps and its application to a few solid electrolytes. The Kelvin Probe Microscopy (KPM) and electrostatic force microscopy (EFM) were considered as alternative methods to investigate ionic systems. A series of surface potential maps could reveal the local distribution and movement of ionic species. However, the geometric convolution between the tip and the surface causes significant artifacts in surface potential measurement. A novel method for suppressing this artifact is presented in this thesis.;For the KPM or EFM, due to the long range property of electrostatic interaction and the finite size of probe, the detected electric signal is obscured and subject to complicated interaction. For that reason, the modeling and analysis of these techniques is crucial to obtain accurate information. Numerical calculations using the boundary element method help to link the observed electrostatic signal with quantitative physical parameters. In addition, this simulation shows the impact of the feature size and the tip geometry on the experimental resolution and accuracy.;Besides the "probing" or "characterizing" capability, a sharp tip enables highly accurate and nano-scale manipulation of ionic species in a controlled fashion. Nano-scaled morphological patterning was performed by applying a sequence of pulsed biases through a fast metal ion conductor film. Additionally, charge patterning on metal oxides (where little morphological change was observed) was observed after a pulsing procedure.