Tunicate-inspired versatile binder for silicon/graphite anodes enabled by co-operation of π–π stacking and hydrogen bonding interactions
Xiangyu Lin, Le Yu, Yong Wen, Luhe Qi, Shanshan Wang, He Liu, Xu Xu, Chaoji Chen
Abstract
Co-utilization of silicon (Si) and graphite (Gr) has become a commercially viable route to achieve higher energy density before the realization of pure Si anodes. However, the challenges of poor dispersion in the aqueous binder and structural stability faced with Si/Gr remain difficult to negotiate. Herein, inspired by the outstanding adhesive ability of pyrogallol-containing proteins in tunicates, a water-soluble binder polyvinyl alcohol-gallic acid (PVA-GA) is synthesized via a one-step esterification reaction. Multiple supramolecular interactions of π−π stacking and hydrogen bonding are introduced to favor the homogeneous distribution of Si/Gr and the excellent structural stability of Si/Gr electrodes. The Si/Gr-PVA-GA delivers a high specific capacity of 568.6 mAh g−1 over 200 cycles, corresponding to 91.5% capacity retention and 0.038% capacity loss per cycle. Furthermore, the good practicality is demonstrated by the stable and safe operation of a Si/Gr||LiNi0.6Mn0.2Co0.2O2 full cell with a practical level of areal capacity up to 3 mAh cm−2.