Coil‐to‐Stretch Transition of Binder Chains Enabled by “Nano‐Combs” to Facilitate Highly Stable SiOx Anode

The commercialized binder carboxymethyl cellulose sodium (CMC‐Na) is considered unsuitable for micro‐sized SiOx anode as it cannot endure the large volume change to retain the conductive network during repeated charge/discharge cycles. Herein, a small amount of silicon nanoparticles (SiNPs) is added during slurry preparation process as “nano‐combs” to unfold the convoluted CMC‐Na polymer chains so that they undergo a coil‐to‐stretch transition by interaction between polar groups (e.g., –OH, –COONa) of polymer and SiNPs’ large surface. Through maximizing the utilization of binders, a uniform conductive network is constructed with increased interfacial contact with micro‐sized SiOx. As a result, the SiOx electrode with optimized (10 wt%) SiNPs addition shows significantly improved initial capacity and cycling performance. Through revisiting CMC‐Na, a currently deemed unqualified binder in SiOx anode, this work gives a brand‐new perspective on the failing mechanism of Si‐based anode materials and an improving strategy for electrode preparation.