Optimisation of powder extrusion moulding process for thick ceramic electrodes of LiCoO2 for enhanced energy-density lithium-ion batteries

Abstract

Lithium-ion batteries are widely used in portable electronic devices because of their high energy and power density. To enhance the energy density of these batteries, one strategy involves increasing the active material loading by increasing the thickness of the electrodes. In previous studies, we demonstrated that powder extrusion moulding (PEM) is a scalable and efficient method for producing additive-free LTO and LFP ceramic electrodes, which exhibit remarkable electrochemical performance with thicknesses up to 500 μm. This study focuses on the preparation and optimisation of the entire manufacturing process for thick ceramic electrodes of LiCoO2 (LCO) with a high mass loading of 180 mg cm−2 using the PEM process. Different powder loadings of mixtures of LCO and a thermoplastic multi-component binder were explored to obtain a formulation suitable for rheology. The optimal formulation comprises 60 vol% of powder. After binder removal via a combination of solvent and thermal treatment, followed by air sintering, parts with varying porosities were obtained. Striking a balance between porosity and thermal degradation is crucial for achieving optimal electrochemical behaviour. Electrochemical evaluations of the electrodes sintered at 900 °C and 1000 °C revealed areal capacity values as high as 17 mAh cm−2 at C/25 and 7 mAh cm−2 at C/6.25, respectively. These values far exceed the 1−2 mAh cm−2 obtained from commercial LCO electrodes. These results indicate a strategy for the production of electrodes to fabricate lithium-ion batteries with a low ratio of inactive materials and, therefore, with higher energy densities.