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

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