Study on the Fading Mechanism of SiO-based Anodes Using Styrene Butadiene Rubber and Carboxymethyl Cellulose as Binders for Lithium-ion Batteries

Three kinds of SiO-based electrodes and one graphite electrode were fabricated using styrene butadiene rubber (SBR) and carboxymethyl cellulose (CMC) as binders. The cycling results showed that the more amount of SiO in the electrodes was, the faster the capacity of the electrode dropped and the lower coulombic efficiency of the electrode performed. Thus, it was the fading of SiO resulted in the SiO-based anodes reversible capacity dropping. In order to analyze the fading mechanism of the SiO-based anodes, SiO electrode was done 10% capacity lithiation/delithiation cycling, during which the volume change of the electrode should be negligible. The results showed that the voltage difference between the maximum and minimum values of the SiO anode cell kept increasing, which indicated that the SiO anode fading happened. The SEM images of SiO anodes illustrated that before cycling, the surface of SiO particles were smooth and tidy, and the SiO particles' edge was sharp, while the surface of SiO particles became roughness, the edge was blurry, and there were fewer conductive additives on the SiO particles' surface after cycling, which implied that electronic conductivity of the electrode became worse after cycling. It can be concluded that electronic conductivity played an important role in the electrode. We believe that boosting the electronic conductivity of the SiO-based electrode is one of the important methods to improve the cell cycle performance.