Dynamic Cross-Linking of Polymeric Binders Based on Host-Guest Interactions for Silicon Anodes in Lithium Ion Batteries

We report supramolecular cross-linking of polymer binders via dynamic host-guest interactions between hyperbranched ?-cyclodextrin polymer and a dendritic gallic acid cross-linker incorporating six adamantane units for high-capacity silicon anodes. Calorimetric analysis in the solution phase indicates that the given host-guest complexation is a highly spontaneous and enthalpically driven process. These findings are further verified by carrying out gelation experiments in both aqueous and organic media. The dynamic cross-linking process enables intimate silicon-binder interaction, structural stability of electrode film, and controlled electrode-electrolyte interface, yielding enhanced cycling performance. Control experiments using both ?, ?CDp with different cavity sizes and a guest molecule incorporating a single adamantane unit verified that the enhanced cycle life originates from the host-guest interaction between ?-cyclodextrin and adamantane. The impact of the dynamic cross-linking is maximized at an optimal stoichiometry between the two components. Importantly, the present investigation proves that the molecular-level tuning of the host-guest interactions can be translated directly to the cycling performance of silicon anodes.NPRP grant (NPRP 7-301-2-126) from the Qatar National Research Fund (a member of Qatar Foundation). Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (2013R1A1A1012282). J.W.C. acknowledges support through the National Research Foundation of Korea (NRF) grant funded by the Korean government (MEST) (NRF-2012-R1A2A1A01011970). National Research Foundation of Korea (NRF) grant funded by the Korean government (MEST) (NRF-2014R1A4A1003712 and BK21 PLUS program).Scopu