The main issue of Si anode is the large volume variations during alloying/dealloying processes, which severely causes the disintegration in the pre-designed conductive and mechanical networks and the interfacial contact between the current collector and Si particles; moreover, it can hardly be overcome economically. Here, the growth methodology of ultrathin graphdiyne nanosheets is scalably developed for in-situ constructing the 3D all-carbon conductive and mechanical networks and firstly enhancing the interfacial contact between current collector and Si anode via chemical bonding. Seamlessly hold by the ultrathin graphdiyne nanosheets, the disintegrations of the silicon anodes in the conductive networks and the interfacial contact are effectively retarded; as a result, the silicon electrode shows impressive enhancements in term of the capacity (2300 mA h g–1), and long-term stability for high-energy-density battery (1343 W h l–1). Such method shows great promises for realizing the commercial-level applications of Si anode.