Rational Design of Robust and Universal Aqueous Binders to Enable Highly Stable Cyclability of High-Capacity Conversion and Alloy-Type Anodes

The development of high-performance binders is a simple but effective approach to address the rapid capacity decay of high-capacity anodes caused by large volume change upon lithiation/delithiation. Herein, we demonstrate a unique organic/inorganic hybrid binder system that enables an efficient in situ crosslinking of aqueous binders (e.g., sodium alginate (SA) and carboxymethyl cellulose (CMC)) by reacting with an inorganic crosslinker (sodium metaborate hydrate (SMH)) upon vacuum drying. The resultant 3D interconnected networks endow the binders with strong adhesion and outstanding self-healing capability, which effectively improve the electrode integrity by preventing fracturing and exfoliation during cycling and facilitate Li⁺ ion transfer. SiO anodes fabricated from the commercial microsized powders with the SA/0.2SMH binder maintain 1470 mAh g⁻¹ of specific capacity at 100 mA g⁻¹ after 200 cycles, which is 5 times higher than that fabricated with SA binder alone (293 mAh g⁻¹). Nearly, no capacity loss was observed over 500 cycles when limiting discharge capacity at 1500 mAh g⁻¹. The new binders also dramatically improved the performance of Fe₂O₃, Fe₃O₄, NiO, and Si electrodes, indicating the excellent applicability. This finding represents a novel strategy in developing high-performance aqueous binders and improves the prospect of using high-capacity anode materials in Li-ion batteries.