Improving Gr/SiO Negative Electrode Formulations: Effect of Active Material, Binders, and Single-Walled Carbon Nanotubes

Abstract

With the growing demand for high-energy-density lithium-ion batteries, silicon oxide (SiO) has emerged as a promising anode material due to its high specific capacity. However, its use entails high irreversible losses and mechanical stress. Pre-lithiated SiO (Li-SiO) blended with graphite enables electrodes with rather low irreversible losses, high specific capacity, and less mechanical stress. However, so far, insights about processing Li-SiO are missing in literature. This work deals with Gr/SiO negative electrodes containing 20 wt% SiO in the active mass. We investigate the effects of different suspension formulations on their rheological properties and the electrochemical performance of the electrodes. Our findings prove superior electrochemical properties of anodes made from Li-SiO compared to pristine SiO. However, we show that the basicity of suspensions containing Li-SiO causes challenges for their processability. The integration of single-walled carbon nanotubes is shown to be essential for counteracting the adverse effects and enabling electrodes with enhanced adhesion, reduced irreversible losses, and stable cycling. A good cell performance is demonstrated with electrodes containing as much as 96.8% of active mass. Our findings provide essential insights into the correlation between formulation, processability, and electrochemical performance of Gr/SiO blends, supporting the development of industrial-scale production processes.