High capacity anode (Silicon, Si) and cathode (Sulfur) electrode materials are receiving a significant amount attention from the battery community due to their exceptionally large capacities that could accelerate the advent of future lithium ion battery applications represented by advanced portable electronics and hybrid electric vehicles. A consequence of the large Li capacity, however, is that the Si anode undergoes significant volume expansion, indeed up to 300%, resulting in severe mechanical and interfacial failures of the electrodes. Hence, for Si anodes, polymeric binders may not play simple passive roles as in conventional battery electrodes, but could rather contribute significantly to decent cell performance. Our systematic investigation of polymeric binders incorporating Meldrum`s acid revealed that most critical binder property for silicon anodes in lithium ion batteries is the self-healing effect facilitated by series of noncovalent ion-dipole interactions. Accordingly, we transferred millipedes’ adhesion mechanism, that is enabled by a synergistic effect between many contacting points based on continuous pairs of legs and several micron-sized adhesive pads decorated with ionic moieties located on each leg, at macroscale to polysaccharide binders at nanoscale in order to clearly demonstrate the effect of ion-dipole interactions in polysaccharide binders for high capacity Si anodes in lithium ion batteries. Recently, we have also reported that supramolecular crosslinking of polymer binders via dynamic host-guest interactions between hyperbranched β-cyclodextrin polymer and a dendritic gallic acid crosslinker incorporating six adamantane units enable intimate silicon-binder interaction, structural stability of electrode film, and controlled electrode-electrolyte interface, yielding enhanced cycling performance for silicon anodes in lithium ion batteries. More recently, we have also demonstrated that by incorporating small amount of polyrotaxanes into the conventional binders, it is possible to form binder networks with unparalleled elasticity, which enabled stable cycle life for silicon microparticle anodes at commercial-level areal capacities.<br/>

Tailoring supramolecular polymers for high capacity electrodes in lithium-ion batteries

256th National Meeting (2018)

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