A Pyrene–Poly(acrylic acid)–Polyrotaxane Supramolecular Binder Network for High‐Performance Silicon Negative Electrodes

Abstract

Although being incorporated in commercial lithium-ion batteries for a while, the weight portion of silicon monoxide (SiO_x , x ≈ 1) is only less than 10 wt% due to the insufficient cycle life. Along this line, polymeric binders that can assist in maintaining the mechanical integrity and interfacial stability of SiO_x electrodes are desired to realize higher contents of SiO_x . Herein, a pyrene-poly(acrylic acid) (PAA)-polyrotaxane (PR) supramolecular network is reported as a polymeric binder for SiO_x with 100 wt%. The noncovalent functionalization of a carbon coating layer on the SiO_x is achieved by using a hydroxylated pyrene derivative via the π-π stacking interaction, which simultaneously enables hydrogen bonding interactions with the PR-PAA network through its hydroxyl moiety. Moreover, the PR's ring sliding while being crosslinked to PAA endows a high elasticity to the entire polymer network, effectively buffering the volume expansion of SiO_x and largely mitigating the electrode swelling. Based on these extraordinary physicochemical properties of the pyrene-PAA-PR supramolecular binder, the robust cycling of SiO_x electrodes is demonstrated at commercial levels of areal loading in both half-cell and full-cell configurations.