Electrochemical Performance of Lithium-Ion Pouch Cells Containing Aqueous Processed and Laser Structured Thick Film NMC 622 and Graphite Electrodes

Abstract

The development of high areal energy density electrodes with layered metal oxide cathode materials is currently a hot topic in research and industry. However, for automotive applications, current research focuses on the merger of two concepts: (i) the “thick-film concept” which enables a high energy density due to a reduced amount of inactive materials, and (ii) the “three-dimensional (3D) battery concept”, which provides a high power density with improved interfacial kinetics at mass areal capacity ≥ 6.5 mAh/cm2. Latter could be realized by applying ultrafast laser patterning of electrodes which in turn includes an advanced 3D electrode design. Briefly, a rapid and homogeneous electrode wetting with liquid electrolyte can be induced, and besides a high capacity retention during long-term cycling. However, the mass loss due to laser patterning needs to be taken into account, since the cathode represents about 50 % of the total material costs of LIBs. Thus, the use of electrode structures with a high aspect ratio as well as a significantly reduced material removal is of great importance. Besides, cost reduction and environmentally friendly production by applying aqueous processing of cathode has been intensively investigated recently. In this work, 150 µm thick-film Li(Ni0.6Mn0.2Co0.2)O2 electrodes were manufactured with both water-based binders and PVDF binder by tape-casting. Both cathodes are anodes were subsequently laser patterned to achieve 3D architectures. Finally, the NMC 622 cathodes were assembled in pouch cells versus graphite anodes for studying the impact of laser patterning and binders on the electrochemical performance by applying rate capability analysis, electrochemical impedance spectroscopy (EIS), and lifetime analysis.