Improving silicon anode durability through uniform dispersion and binding enhancement with polyacrylamide-grafted carbon nanotubes

Silicon (Si) anodes offer a high specific capacity (> 3,500 mA h g-1), but severe volume changes during cycling and poor intrinsic conductivity hinder commercialization. Carbon nanotubes (CNTs) are commonly incorporated to improve the electronic conductivity of Si electrodes, but their tendency to aggregate in polar solvent-based slurries leads to non-uniform electrodes. To address this, we synthesize polyacrylamide-grafted CNTs (PAM-g-CNTs) by covalently attaching hydrophilic acrylamide monomers to CNT surfaces. The PAM chains provide steric hindrance that minimizes van der Waals interactions between PAM-g-CNTs and interacts effectively with polar solvents, thus promoting uniform dispersion and forming a stable electron-conductive network within the electrode. Furthermore, PAM-g-CNTs establish hydrogen bonds with Si particles and binder matrices, enhancing the structural integrity of the electrode. The cycling performance of Si half cells incorporating PAM-g-CNTs shows substantial durability after 200 cycles. Moreover, in high-energy-density Si electrode configurations with reduced binder and conductive agent ratios (active material > 70%), PAM-g-CNT-based cells preserved 70% of their initial capacity after 100 cycles, compared to only 20% retention in Super P-based cells. The functionalization of CNTs with hydrophilic PAM thus proves effective in improving dispersion stability and conductivity while reinforcing electrode cohesion. This strategy presents a promising path for developing durable Si anodes for high-energy-density lithium-ion batteries.