N-Doped Carbon Dots Assist Crosslinked Binder in Enhancing Ion Transport and Interface Stability of Silicon Anodes

Silicon (Si) anodes offer high capacity but suffer from large volume changes and unstable electrode-electrolyte interfaces. Conventional binders rarely provide both robust mechanical stability and efficient ion transport. Here, a multifunctional crosslinked binder (XC₅Ns_0.3) is designed via the in situ esterification between carboxyl styrene butadiene rubber (XSBR) and prelithiated carboxymethyl cellulose (CMCLi), with glycerol serving as a dual-functional polyhydroxyl component and nitrogen-doped carbon dots (N-CDs) incorporated to regulate ion transport. The resulting covalent and gradient hydrogen-bonding network delivers exceptional mechanical strength, disperses stress, and preserves electrode integrity. Meanwhile, uniformly distributed N-CDs significantly enhance ionic conductivity (1.12 × 10^-2 S cm^-1) and promote the formation of a stable, LiF-rich solid electrolyte interphase (SEI) layer. As a result, the XC₅Ns_0.3-based anode achieves a high initial coulombic efficiency (ICE) of 91.2% and retains 1685.1 mAh g^-1 after 550 cycles at 0.2 C. A full cell with a LiNi_0.52Co_0.2Mn_0.28O₂ (NCM523) cathode further validates its practical potential. Overall, this work presents a scalable strategy that concurrently addresses the mechanical and electrochemical challenges of next-generation high-energy-density lithium-ion batteries (LIBs).