Enabling Ultrafast Charging in Graphite Anodes Using BIAN-Based Conjugated Polymer/Lithium Polyacrylate as a Binder

The facile diffusion of Li+ ions through the solid electrolyte interphase (SEI) is crucial to realize extremely fast-charging (XFC) batteries. Graphite is a promising candidate for electric vehicles and other battery applications. However, it exhibits a poor delithiation capacity due to exfoliation under high current rates. Therefore, herein, a composite polymer binder, named BIAN-LiPAA, with intrinsic Li+ ions, was prepared to achieve fast charging and better ion diffusion. The remarkably low-lying energy level of the lower unoccupied molecular orbital of the BIAN-LiPAA binder makes it an n-doped composite binder in an anodic environment, which leads to the reduction of the binder before electrolyte degradation to form a thin and conducting SEI. The proposed composite binder exhibits a considerably low SEI, charge transfer resistance, and an activation energy of 21.00 kJ/mol with improved Li+ diffusion in the graphite matrix (2.86 × 10–10 cm2 s–1). Anodic half-cells fabricated using the BIAN-LiPAA binder exhibit discharge capacities of 276, 114.5, and 62.1 mAh/g at 1C, 5C, and 10C, respectively, considerably higher than those of the PVDF-, LiPAA-, and P-BIAN- based cells. Under XFC conditions, BIAN-LiPAA exhibits high-capacity retentions of 94.2 and 83.5% at 10C and 5C, respectively, after 2000 charge–discharge cycles.