Silicon anodes are a key component for high-energy lithium-ion batteries (LIBs). Electrode binder engineering for Si anodes has been calling increasing awareness. Here, we report a series of molecularly engineered conductive polymer binders, that is, star-like polyaniline (s-PANi), cross-linked polyaniline (c-PANi), and linear polyaniline (l-PANi). As a conductive binder, the molecular structure of PANi was found to play a key role in determining the performance of a Si anode: a reversible capacity of 1776 mAh g(-1) after 100 cycles at 500 mA g(-1) was achieved using s-PANi as the conductive binder, far superior than systems adopting c-PANi, l-PANi, and conventional carboxymethyl cellulose binders. The correlation between the binder molecule structure and Si anode performance is found: a star-like molecular structure is more advantageous over the heavily cross-linked structure for it offers a 3D-conjugated conductive network that is more resistant to cycle-induced large strain.