Sulfonic Group Modified Binder Endows Rapid Lithium‐Ion Diffusion for SiOx Microparticle Anode

Silicon-based materials have been regarded as the most flourishing anode materials owing to the incomparable specific capacity. However, their commercial application is obstructed by huge volume expansion and particle pulverization, which subsequently lead to the stress concentration and the loss of electrical contact, eventually resulting in poor cycling stability and lousy rate performance. Herein, an ion-conductive binder with boosted ion-conductivity is proposed by free radical polymerization between acrylic acid and lithiated 2-acrylamido-2-methyl-1-propanesulfonic acid (LiAMPS). With the aid of ample sulfonic acid anionic groups, rapid lithium-ion diffusion can be achieved to improve the transport kinetics and rate performance. Meanwhile, superior mechanical properties of binder can alleviate the stress concentration to avoid particle pulverization by noncovalent hydrogen bond. The synergistic strategy of constructing lithium-ion diffusion pathway and alleviating the stress concentration can make a preeminent improvement on Li⁺ diffusion coefficient and maintain a high structural integrity of electrode. Benefiting from the synergistic effect, the SiO _x microparticle anode delivers a high capacity of 587.8 mAh g^-1 after 400 cycles at 1C and preeminent rate performance of 648.6 mAh g^-1 at 5C. Such a synergistic design strategy endows P(AA-co-LiAMPS) binder with a promising potential for high energy density silicon-based anodes.