Effects of carbon coating on calendered nano-silicon graphite composite anodes of LiB

Recently, silicon has attracted attention as anode material for lithium-ion batteries, but the periodic volume change leads to poor cycling stability. Two promising strategies to overcome this are the use of nanoparticles and the combination with graphite. In our previous study, a process route for production of silicon-on-graphite composites ([email protected]) with 10 wt% silicon via fluidized bed granulation and carbon coating ([email protected]/C) was presented. Within this study, the process has been scaled up to pilot scale and the effects of carbon coating on particle level combined with a comprehensive calendering study were investigated in more detail. It could be shown, that the carbon coating reduces the surface area, stabilizes the composite and enhances electrical conductivity. Based on porosity measurements, a disintegration of the composites most likely occurred as a consequence of the high shear stresses. The electrochemical performance revealed a significantly enhanced capacity retention after 125 cycles ([email protected]: 82.2% vs. [email protected]/C: 91.9%). After calendering, the positive impact of carbon coating was even more pronounced. While [email protected] suffered from accelerated degradation with increasing electrode density, calendering had only minor impact on [email protected]/C. This study advances the understanding of the positive effects of carbon coating for the calendering of nano-Si containing electrodes.