Freely-Rotatable Multidentate Molecular Anchor Enables Self-Adaptive Aqueous Binders for Lithium-Ion Batteries

The rational design and synthesis of reliable binders is a big challenge to efficiently mitigate the severe volume change of silicon-based anodes for lithium ion batteries. Herein, we report a multidentate molecular anchoring strategy to construct a novel self-adaptive aqueous binder. This binder composes of robust 3D dynamic networks derived from the crosslinking of the freely-rotatable multidentate molecular anchor (2,2-bis(hydroxymethyl)butyric acid, BHB) and polyacrylic acid (PAA) via dynamic hydrogen-mediated self-assembly, which effectively imparts the fabrication of high-strength Si/C anodes and achieves high areal capacities (6.13 mAh cm^-2) under a high mass loading of 13 mg cm^-2. Furthermore, the dynamic and reversible adhesion and the efficient "net-to-point" bonding characteristic contribute to enhance structural and interfacial stability in the NCM811/Si/C full cells. Consequently, the cells demonstrate superior cyclability and electrochemical performance. Notably, this multidentate molecular anchoring strategy can be further extended to develop other BHB-derived self-adaptive binders (i.e., BHB/PVA and BHB/CMC) for the purpose of dynamic structure regulation. This work provides valuable insights into the judicious modulation of aqueous binders from the perspective of molecular chemistry and product engineering, paving the pathway for the design of auqeous binders for ultra-high-energy Si-based lithium-ion batteries.