H-Bond Network-Regulated Binder for Si/Graphite Anodes

Silicon-based anode materials attract ever-increasing attention owing to their high theoretical capacity. However, their practical application is significantly hindered by the dramatic volume change during the charge/discharge process, during which not only the solid electrolyte interface (SEI) but also the electrode might be ruined. Here, we propose a H-bond network-regulated binder by introducing low-molecular-weight cross-linkers, lithium oxalate and alpha-cyclodextrin (alpha-CD), into alginate (Alg). The balance between the binding strength and Li ion diffusion is realized through the control of the ratio between them. Lithium oxalate and alpha-CD can effectively regulate the H-bond network of the binder by forming intermolecular dynamic H bonds with Alg and reducing the intramolecular ones. Although the hybrid binder shows lower adhesion force than Alg, better electrode integrity is obtained during the charge/discharge process. Meanwhile, Li+ transportation is facilitated due to extra Li+ supplied by lithium oxalate, thereby achieving better rate capability.