Coordinatively-intertwined Dual Anionic Polysaccharides As Binder with 3D Network Conducive for Stable SEI Formation in Advanced Silicon-Based Anodes

The rational design of stable binders targeting silicon electrodes with high theoretical capacity is vital for their superior electrochemical performance. Owing to the drastic volume change of silicon electrode upon long-term cycling, unstable SEI layer accompanying with low initial Coulombic efficiency (ICE) deteriorate the battery performance severely. In this case, we propose a 3D network binder (SHA) by weaving two anionic polysaccharides (i.e., hyaluronic acid (HA) and soluble soybean polysaccharides (SSPS)) via supramolecular interactions. Driven by the distinct chain flexibility, the two polysaccharides microphase-separate into internal buffer region (hard SSPS) and external restricted region (soft HA), resulting in double-layer network of SHA. The resulted hard/soft scaffold can not only significantly confine the disintegrated Si electrodes, but also guarantee a 3D continuous ion transportation circuit. Consequently, the SHA binder effectively assists the formation of stable SEI layer and achieves an excellent ICE up to 92.67%, leading to a satisfying rate capability and stable cycling performance for 250 cycles at 2 A g-1, with a capacity decay rate of 0.24% per cycle. This novel and facile strategy delivers a perspective binder design through alternative combination of anionic, cationic and neutral polysaccharides for high performance Si anodes.