Effect of crosslinking binders on Li-storage behavior of silicon particles as anodes for lithium ion batteries

To gain insight of the effect of binders on interfacial behaviors is crucial for the design of binders for Si-based lithium ion batteries. Herein, we develop a method to generate the cross-linked polymer binder, via esterification between polyacrylic acid and sodium alginate, during the formation of the electrode. Compared to the sodium alginate binder, an improved electrochemical performance of the commercially available submicro-sized Si particles is obtained with the cross-linked polymer binder. The initial specific discharge capacity increases to 2471 mAh g−1 with a Coulombic efficiency (86.8%) of the electrode with the cross-linked polymer binder, relative to that of 2371 mAh g−1 with a Coulombic efficiency (82.6%) of the electrode with sodium alginate. After 110 cycles at 200 mA g−1, the electrode with the cross-linked polymer binder can deliver a discharge capacity of 945 mAh g−1 with a capacity retention of 38.2%, superior to those of the electrodes with sodium alginate. The electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy data demonstrate that the tight binding of the cross-linked polymer binder can greatly improve the interface stability, resulting in the formation of less solid electrolyte interphase film, and less poor electronic/ionic conductive species at the interface of the Si particles. Thus, a proper design of binder with a flexible three-dimensional network and adhesion ability to the Si particles would be advantageous for improving performance of Si particles toward lithium storage.