Silicon Microparticle Anodes with Self-Healing Multiple Network Binder

Si has been regarded as a promising anode material for Li-ion batteries. However, its dramatic volume change during cycling poses formidable challenges to building stable electrodes. Since Si microparticles (SiMPs) can easily cause the pulverization and loss of electronic contact, many previous works were focused on porous-structured, nanostructured, or hierarchically structured silicon materials to improve the cycle stability. However, their low-cost and mass production is mostly difficult or even impossible. Herein, a water-soluble polymer binder, poly(acrylic acid)-poly(2-hydroxyethyl acrylate-co-dopamine methacrylate), is designed and synthesized. It shows better wettability to liquid electrolyte than poly(acrylic acid). Moreover, its multiple network structure with rigid-soft chains and bonds, and special self-healing capability in situ formed during the electrode preparation, not only provides enough mechanical support but also buffers the strain caused by the volume change of SiMPs. Thus, the cycle stability and rate performance are remarkably improved under high reversible capacity or electrode loading.