A multifunctional polyelectrolyte binder to improve fast charging capability of graphite anode in lithium-ion batteries

The sluggish lithium-ion diffusion kinetics and severe lithium plating under fast charging conditions significantly impair the fast charging ability of graphite anode. Herein, water-soluble polyelectrolyte binder cellulose sulfate lithium (CSL) is employed as a multifunctional binder to enhance the extremely fast charging (> 4C) ability of the graphite anode. The CSL binder contributes to forming a uniform and thin solid electrolyte interphase layer, greatly reducing surface layer resistance. The –SO 4 Li groups also provide additional lithium ions, which prominently promote the diffusion of lithium ions. Furthermore, a number of –SO 4 Li and –OH groups in the binder can form robust hydrogen bonds with oxygen-containing groups from the graphite and collector, ensuring the cycling stability of graphite anode. Consequently, at 1C, the discharge specific capacity of the graphite anode using CSL (Gr-CSL) reaches 346.9 mAh g −1 , and it still has a specific capacity of 335.5 mAh g −1 with a retention rate of 96.7% (vs. 100 cycles) after 1000 cycles. At 5C, the Gr-CSL anode displays a reversible capacity of 147.3 mAh g −1 , much higher than 111.4 and 50.3 mAh g −1 using polyvinylidene fluoride and sodium carboxymethyl cellulose. Even after 1200 cycles, it still maintains a capacity of 132.8 mAh g −1 and an average coulombic efficiency of 99.89%. These results offer novel perspectives into the reasonable design of binders for the graphite anode with fast charging capability.