Undervalued Roles of Binder in Modulating Solid Electrolyte Interphase Formation of Silicon-Based Anode Materials.

The use of silicon (Si) for lithium (Li) storage has the significant merits of an ultrahigh theoretical specific capacity and a low working platform, potentially enabling a high-energy-density Li-ion battery (LIB). However, the Si itself undergoes a huge volume variation (>300%) upon the lithiation/delithiation process, which inevitably causes material pulverization and electrode cracking as well as ceaselessly repairs the solid electrolyte interphase (SEI), eventually resulting in a rapid capacity decay of the Si anode. Presently, using a robust binder has been well-recognized as an effective solution, which is generally explained by its robust mechanical properties that enable the electrode integrity of the Si anode during the repeated cycling process. Comparatively, the roles of the binder in modulating the chemical composition and the spatial distribution of the Si-based SEI layer are overlooked. This review will specifically provide an overview of the correlation between the binder species and SEI properties. The binder species have a critical role of inducing a robust SEI layer by selectively allowing the electrolyte salt and the solvent to connect the Si surface in the initial discharging process. Finally, we conclude by providing the perspective of the binder design based on interfacial chemistries and new characterization techniques.