Cheap, high-performance, and safe energy storage solutions are needed to address the increasing demand for portable electronics and the transition to electric mobility. Lithium-ion batteries have replaced conventional secondary battery technology (like nickelcadmium and nickel-metal hydride batteries) due to their high energy densities, high operating voltages, and stable capacity retention during open-circuit rest. Lithium metal anodes were quickly replaced by lithium-intercalated graphitic materials in order to avoid the formation of dendrites that resulted in short circuiting of the two electrodes. However, while lithium-graphite intercalates are safer and more stable they have only a tenth of the energy density of metallic lithium. Silicon is a good active material for Li-ion anodes because it has a superior theoretical capacity of 3579 mA h g -1 (or 8340 mA h cm -3 ) for Li15Si4, andunlike some transition metalsit is not toxic and abundant. Moreover, its alloying reaction with lithium triggered at 0.3 V vs. Li/Li + , prevents the formation of metallic lithium around the anode during discharginga detrimental process observed for Ligraphite batteries known as "lithium plating"and allows the use of Si-Li electrodes under harsher conditions. The large number of lithium atoms that silicon can store, however, induces large volume changes during charge/discharge cycles (>300%). The mechanical stress induced by these drastic volume changes leads to the pulverization of the silicon active material, loss of contact of the electrode film with the current collector, and loss of overall mechanical integrity of the whole electrode. Repeated cycles of expansion and contraction of silicon expose pristine silicon surfaces and induce the reformation of solid electrolyte interfaces (SEI). This process contributes to the gradual consumption of lithium and electrolyte, and it limits the diffusion of charge carriers through the expanding SEI. It is difficult to counter these detrimental mechanical and chemical changes to silicon-based electrodes because conventional methods of electrode assembly rely on the mixing of multiple components that are held together by weak, dispersive forces. In laboratory settings, some strategies were developed to address the inherent flaws of these multi-component assemblies. For example, shaping silicon into hierarchical, nano-sized, or porous structures buffers some of its dramatic volume expansion during lithiation. On the downside, nanostructured silicon is susceptible to restructuring during battery operation, and its larger specific surface promotes reactions with the electrolyte to form more of electrochemically inactive SEI. In other approaches silicon particles are encapsulated in a carboneous matrix, or they are coated with metal oxides. However, encapsulation of silicon requires supplementary components that do not meaningfully contribute to the volumetric capacity of the electrode and might necessitate the addition of agents that enhance electric conductivity. Such modifications of the active material prior to electrode assembly have proven too time consuming, low yielding and expensive and, hence, none of these methods have found their way into commercial processes to date. In this work, we present a departure from the current "blend-andbake" paradigm of electrode manufacture. In a one-pot process, we embed silicon nanoparticles (Si NPs) in a covalently-linked, porous, semi-conducting polymer matrix whose growth is initiated and templated by the current collector (Cu) itself. The covalent bonds of the organic matrix contribute to a superior mechanical and chemical resistance of our electrode films. The overall πconjugated backbone of the triazine-based graphdiyne (TzG) polymer enables the transport of electrons from the active material to the current collector. Since the polymerization is promoted by the reactive metal surface of the current collector, the resulting polymer/silicon composite (TzG/Si) adheres strongly to it. In summary, the covalent polymer matrix acts at the same time as (i) a strong binder, as (ii) an electrical conductor, and as (iii) a semi-permeable membrane that enables transport of ions and electrolyte but prevents the migration of homogeneously dispersed silicon nanoparticles even under harsh conditions. This facile method yields silicon-based anodes (TzG/Si@Cu) of superior performance that suffer little mechanical and electrochemical deterioration from the inherent volume expansion of silicon during lithiation-delithiation cycles and that drastically limit the detrimental loss of lithium and electrolyte at the solid electrolyte interface.