Investigating the effect of the degree of cross‐linking in styrene butadiene rubber on the performance of graphite anodes for the use in lithium‐ion batteries

Abstract

Carboxymethyl cellulose/styrene butadiene rubber (CMC/SBR) has been proven to be an effective binder system for the use of graphite anodes within the lithium‐ion battery industry. However, often when this system is employed, there is no acknowledgement regarding the specific chemistry of the SBR used. This is an important omission because properties such as glass transition temperatures and tensile strengths are heavily dependent on the ratio of styrene to butadiene content and the degree of cross‐linking within the SBR. In this study, we investigate the impact of using styrene butadiene rubbers (SBRs) with different degrees of cross‐linking on the performance of graphite anodes. We demonstrate that SBRs with a higher degree of cross‐linking provide longer and more stable capacity retentions, than SBRs with a lower degree of cross‐linking. This was found to correlate with the adhesion and cohesion strengths of the electrode coatings, and the degree of electrolyte swelling the SBRs systems undertook. Overall, the findings from this study indicate that the degree of cross‐linking within the SBR impacts the overall performance of the battery.