Probing the electronic conductivity of battery electrodes

Abstract

Improving advanced battery technology have been a focus within the sustainable energy space, where battery performance becomes hindered by defects that impair their efficiency and electrical characteristics. A common quantity to measure is the electrical conductivity of electrodes. Typically, they are measured using the Four Point Probe (4PP) method to attain an average value. However, this method has the drawback where it potentially causes damage, where the physical properties of the material become altered under plastic deformation. To address this issue, the implementation of a load cell design aims to alert users during 4PP measurements and prevent them from exceeding the mechanical limits of tested materials. A novel method to characterising electrical conductivity of battery samples is also proposed with the Sixteen Point Probe (16PP) method, which adopts the conventional Four Point Probe (4PP) method to create a heatmap/image reconstruction to a 2-dimensional conductivity distribution of them. By using the Electrical Impedance Tomography and Diffusion based Optical Tomography Reconstruction Software (EIDORS) MATLAB program to process measurements and estimate the inhomogeneity of battery electrodes, the 16PP method is accurate in reconstructing the geometry of localised defects on measured samples. We verified the method’s capability in distinguishing regions of high and low conductivity through comparing the average range of values from its estimations with the 4PP method measurements. Our findings determine that EIDORS is capable in producing reliable results and improvements to its algorithm can improve accuracy and resolution. The insights gained from this thesis will pave the way to further develop and refine the methodology to characterising battery electrodes.

Date of Award	2025
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology
Supervisor	Qing CHEN (Supervisor)