Challenges, laser processing and electrochemical characteristics on application of ultra-thick electrode for high-energy lithium-ion battery

Lithium ion battery with ultra-thick electrode is hardly manufactured in practice due to its poor rate capability and large unusable capacity caused by high internal resistances in spite of the potential benefits of a high capacity and cost reduction by less inactive material usage in the same volume. In this work, we report the effectiveness of laser structuring of ultra-thick electrodes for high-energy battery. Lithium cobalt-oxide cathode (700 μm) and graphite anode (650 μm) are prepared with the areal discharge capacity, 25 mAh cm−2. After laser structuring, electrode surface morphology and chemistry are investigated. Internal resistances and diffusion characteristics are analyzed by electrochemical impedance spectroscopy using symmetric cells with non-intercalating salt. Geometric changes of ultra-thick electrode by laser structuring contributes to decrease of tortuosity, decrease of electronic and ionic resistances, and enhancement of diffusion characteristics in both laser-structured cathode and anode without chemically negative reaction, thermal damage or a failure of electrode structure. The rate capability and areal discharge capacity of laser-structured cells increases by 5 times than that of unstructured one at 0.1 C condition. Therefore, laser structuring of ultra-thick electrodes is a viable approach for the high-energy battery with practical use of space.