Metal‐Coordination Mediated Polyacrylate for High Performance Silicon Microparticle Anode

Abstract As opposed to nano‐Si anodes, Si‐microparticle (Si‐MP)‐based negative electrode is still in an immature stage due to the fragility of particles of which dimension is farther from the critical size of Si. In terms of binder chemistry, the established strategies for nano‐Si anode can be moderately transferred to designing functional binders for commercially available Si‐MP. However, only a few studies have reported acceptable electrochemical properties of Si‐MP in the level of designing novel‐binder systems. Herein, the ionically crosslinked polyacrylate (PANa_0.8Fe_y) inspired by metallo‐supramolecular polymers is introduced as a binder for Si‐MP anode. Although cracking of Si‐MP is inevitable during cycles, the electrode components can effectively be confined within the supramolecular network, which reversibly adjusts its architecture via iron (Fe³⁺)‐carboxylate coordination. With appropriate compositions, the incorporation of ferric ion to sodium polyacrylate allows the Si‐MP to exhibit an excellent round‐trip capacity of ∼1400 mAh g⁻¹ after 400 cycles. The resulting electrochemical performance is demonstrated by several correlated factors: (i) type of supramolecular interactions, (ii) effect of cations (Na⁺/Fe³⁺) on the conformation of polymer, and (iii) mechanical properties of the electrode.