Electrochemical analysis of laser structured ultra-thick electrode for high energy lithium-ion battery

Abstract

Lithium ion battery with ultra-thick electrode is hardly manufactured in practice due to its poor rate capability and large unusable capacity resulting from the high internal resistance in spite of the potential benefits of high energy density and cost reduction by less inactive material usage. In this work, we report the effectiveness of laser structuring of ultra-thick electrodes on performance enhancement. The full cell for experiment is fabricated with laser-structured and unstructured ultra-thick lithium cobalt oxide cathode (700 m) and graphite anode (650 m). The electronic and ionic resistances of the laser-structured and unstructured electrodes are measured by electrochemical impedance spectroscopy using symmetric cells with non-intercalating salt. Polarization analysis is carried out using a galvanostatic intermittent titration technique. The rate capability of laser structured full cell increases by 6 times from that of the unstructured one and the usable capacity by 4 times despite of electrode mass loss at 0.1 C condition. It is explained by the result of reduced polarization of the laser structured electrode. In addition, it is found that the electronic resistance of cathode decreased by 90 % while the ionic resistance in both cathode and anode decreased by 60 %, contributing to the observed battery performance.