Systematic investigation of the Binder's role in the electrochemical performance of tin sulfide electrodes in SIBs

Binders play a significant role in the electrochemical performance of electrodes in batteries, especially for high-capacity conversion/alloying-type electrodes. However, the effects of binders on the electrochemical performance of the conversion/alloying-type anodes in sodium ion batteries are not widely investigated. In this work, we use SnS 2 as a model anode and comparatively investigate the performance of six different types of binders in SnS 2 electrodes of sodium ion batteries by half-cell testing. The binders are sodium carboxymethyl cellulose (CMC-Na), sodium polyacrylate (PAA-Na), CMC-Na-PAA-Na (1:1, wt%, denoted as PAA-CMC), sodium alginate (ALG-Na), PVDF, PTFE. The PAA-CMC binder electrodes exhibit outstanding cycling and rate performance, delivering a reversible capacity of 400 mAh g −1 at the current density of 100 mA g −1 within 70 cycles. Our results indicate that the binder with a large fraction of carboxylate and hydroxyl groups, which lead to stronger hydrogen bonds and/or covalent chemical bonds with the carbon black and active materials, is advantageous for the electrochemical performances of SnS 2 electrodes. The synergistic interactions among the binder and the surface of both the active materials of SnS 2 and the conductive additive of ketjen black have been also schematically proposed in this study.