Effect of polyimide binder on electrochemical characteristics of surface-modified silicon anode for lithium ion batteries

Si nanostructures with high surface area are prepared by Ag-assisted chemical etching, and then employed as an anode material for lithium ion batteries. The use of the surface-modified Si, which has four times higher surface area than its pristine counterpart, leads to the enhancement of electrochemical performance characteristics such as discharge capacity and coulombic efficiency. In order to optimize the electrode constituents, two different binders, poly-vinylidine difluoride (PVdF) and polyimide (PI), are evaluated on the basis of electrochemical and physical tests. In-situ dilatometer and nano-indentation studies during repeated charging and discharging cycles for the different binders reveal more stability and recuperative capability against physical stress with the PI binder than with the PVdF. The optimized active structure combined with the film-like binder plays an important role in enhancing the electrochemical performance.

► Si nanostructures are prepared by Ag-assisted chemical etching.
► The choice of PI binder for Si nanostructure is very important.
► The employment of PI binder improves electrochemical performance.
► The mechanical properties of PI mitigate the volume change of Si electrode.
► The proper selection of binders such as polyimide is one of the key factors.