Ternary Cross-Linked Multi-Functional Blended Polymers for High-Performance Silicon Anodes in Lithium-Ion Batteries

Abstract

Silicon (Si) based anode material is highly attractive for next-generation lithium‐ion batteries (LIBs) due to its unparalleledtheoretical capacity and abundance. However, a severe problem of Si is the significant volume change associated with thelithiation processes, resulting in reduced capacity retention. Researchers have traditionally considered the roles ofinteractive binders and conductive additives as separate entities. These two components often lead to remarkablydecreased mass ratio of Si to nonactive material, which inevitably limits the electrode capacity. To achieve an enhanceutilization efficiency, herein, we have developed a multifunctional nanocomposite binder for high capacity nano-size Sibasedmaterial through a cross-linked polymer of carboxymethylcellulose (CMC), polyacrylic acid (PAA) spine withgraphenized polyacrylonitrile (PAN) through a gradual carbonizing route. This nanocomposite strongly interacts with Simaterial, providing a robust nanoarchitecture with abundant conductive pathways for Li-ion transport. CMC and PAA with alarge number of carboxyl groups provide binding ability by sturdy three-dimensional (3D) cross-linked network with relativelya thin SiO2 mechanical binding film on the surface of Si nanoparticles onto a highly porous carbon and forming a stablesolid electrolyte interface (SEI) layer. Meanwhile, graphenized PAN provides a highly interconnected conductivenanoarchitecture of a nitrogen-doped graphenized-like structure (NG), which provides enhanced pathways for lithium iondiffusion. Without any conductive additives, this nanocomposite material not only shows a high superior 1st dischargecapacity of 3473 mAh g-1, high initial Coulombic efficiency of 89%, excellent rate capability, and remarkable cycling life formore 600 cycles when cycled at high current density of 3000 mA g-1, but also maintaining good cyclability with a constanthigh areal capacity of ~ 2.7 mAh cm-2. Together with the ease of fabrication, this provides a promising avenue forcommercial LIBs. Figure 1