Carbon nanotubes grafted conductive polymer constructs robust multi-scale conductive pathways for high-performance anodes

As the representative high-performance anode, the performance of silicon-based anode in high-energy lithium-ion batteries is hindered by significant volumetric fluctuations and poor conductivity. Carbon nanotubes (CNTs) have emerged as pivotal conductive additives and structural stabilizers in silicon-based electrodes. However, the insulation of commercial binders and their limited interaction with CNTs prevent the CNTs from performing their intended roles, particularly in commercial electrodes with high anode material content. To address this, the study introduces a novel conductive binder (PCNT) by grafting conductive polyfluorene onto the surface of CNTs. The long/short-range electron transport channels intertwine to form a dense, multi-scale conductive network, which endows the binder with remarkable conductivity and efficient electron transfer at the CNTs interface, significantly reducing voltage polarization in graphite/SiO_x electrodes and enhancing rate performance. Even with an ultra-low binder content (5 wt % without other additives), the constructed robust framework effectively suppresses electrode expansion and internal void cracking, which helps decelerate the aging process of solid-electrolyte interphase (SEI). Thus, it maintains the integrity of the electronic percolation network, improving the cycling stability of the electrodes. The effective synergy between conductivity, adhesiveness, and mechanical properties offers new insights into the application of CNTs and conductive polymers in silicon-based electrodes.