Effect of SBR/CMC Binder Ratio on the Electrochemical and Mechanical Properties of NG/c-SiO Composite Negative Electrodes

The effects of binder composition on natural graphite (NG)/carbon-coated silicon monoxide (c-SiO) composite electrodes were investigated by varying the ratio of sodium carboxymethyl cellulose (CMC) to styrene-butadiene rubber (SBR). A higher CMC content improved cycling stability, rate capability, and reduced resistance, but also increased electrode brittleness. In contrast, a higher SBR fraction enhanced mechanical flexibility but compromised electrochemical stability. Electrode resistivity and GITT analyses confirmed that CMC promotes strong interfacial adhesion and well-established electron transport pathways. Overall, the results demonstrate a clear trade-off between electrochemical performance and mechanical durability and suggest that a balanced SBR/CMC ratio provides the most reliable route for practical NG/c-SiO composite negative electrodes.