Development of Dual-Functional Polyamide Imidazole Binder for Silicon Anode Lithium-Ion Battery

Abstract

Silicon (Si) is one of the most promising anode materials in lithium-ion batteries (LIBs). However, Si undergoes a huge volume change during charging/discharging and induces intractable problems such as delamination, cracking of electrode, and unstable solid electrolyte interphase. Polymer binder is one of powerful strategies to prevent the problem. In this study, the novel polyamide imidazole (PAID) binder is synthesized and forms imide and imidazole intermediate phase (i-PAID) at electrode fabrication temperature. The i-PAID binder have strong interaction with Si particle and carbon black by ambidextrous binding effect. Introduction of amine and carboxylic acid in i-PAID binder enhances adhesion force of the Si particles. In addition, the extended polymer backbone of i-PAID improves not only inter-molecular interaction with carbon black by π-π stacking interaction but also sustains robust conduction pathway in Si anode. The Si anode with i-PAID binder confirmed outstanding mechanical durability of Si during charging/discharging through in-situ electrochemical dilatometer and ex-situ SEM observation. It exhibited higher reversible capacity and stable cycle performance for 200 cycles at 0.2C than the Si anode with commercial polyimide binder, respectively. Thus, the ambidextrous polymer binder would propose new molecular design concept for Si anode in LIBs.