Probing carbon black deagglomeration in lithium-ion battery cathode manufacturing using powder resistivity metrics

Abstract

Carbon black dispersion is critical to achieving a percolated network in lithium-ion battery electrodes. Existing knowledge relies on legacy insights, lacks mechanistic understanding, and direct quantification of dispersion remains challenging due to nanoscale particle sizes. This study presents the first mechanistic investigation of carbon black deagglomeration via mechanofusion, using powder resistivity to examine deagglomeration behaviour, linking dry mixing parameters, CBD structures and coating characteristics. Low powder resistivity can be achieved with a short mixing time, while optimal mixing speed depends on carbon loading and mixing time. Inadequate mixing results in inhomogeneous distribution of conductive additives, and excessive mixing breaks down large carbon black structures necessary for long-range conduction, increasing powder resistivity. While powder resistivity correlates with deagglomeration, it does not directly predict electrochemical performance. These findings highlight the importance of a combination of long and short-range contacts in the carbon binder domain, facilitated by conductive carbon coatings, to enhance electrochemical performance. This work introduces a practical technique to assess carbon black deagglomeration, traditionally evaluated through slurry, electrode, or cell-level properties. Powder resistivity can be effectively used to correlate carbon black structures with dispersion during mixing, providing a valuable tool for data-driven optimisation of mixing processes and conductive network formation.