Precursor polymers for the carbon coating of Au@ZnO multipods for application as active material in lithium-ion batteries

The synthesis of statistical and block copolymers based on polyacrylonitrile, as a source for carbonaceous materials, and thiol-containing repeating units as inorganic nanoparticle anchoring groups is reported. These polymers are used to coat Au@ZnO multipod heteroparticles with polymer brushes. IR spectroscopy and transmission electron microscopy prove the successful binding of the polymer onto the inorganic nanostructures. Thermogravimetric analysis is applied to compare the binding ability of the block and statistical copolymers. Subsequently, the polymer coating is transformed into a carbonaceous (partially graphitic) coating by pyrolysis. The obtained carbon coating is characterized by Raman spectroscopy and energy-dispersive X-ray (EDX) spectroscopy. The benefit of the conformal carbon coating of the Au@ZnO multipods regarding its application as lithium-ion anode material is revealed by performing galvanostatic cycling, showing a highly enhanced and stabilized electrochemical performance of the carbon-coated particles (still 831 mAh g^-1 after 150 cycles) with respect to the uncoated ones (only 353 mAh g^-1 after 10 cycles). The carbon coating of Au@ZnO heteroparticles using anchoring carbon precursor polymer is described in this article. Carbon-coated particles are applied as alternative anode material in lithium-ion batteries, showing a substantially enhanced performance compared to uncoated particles.