We report direct manufacturing of high-capacity carbon/silicon composite fiber electrodes for lithium-ion batteries produced via a flexible low-cost melt processing route, yielding low-cost stable silicon particles coated insitu by a 10nanometer thick protective silica layer. The core-shell silicon/SiO2 islands are embedded in electrochemically active and electronically conductive carbon fiber derived from lignin precursor material. The silicon-silica-carbon composites exhibit capacities exceeding 700mAhg-1 with Coulombic efficiencies in excess of 99.5%. The high efficiency, stability, and rate capability are linked to the nanocrystalline structure and abundant, uniform nanometer-thick SiO2 interfaces that are produced during the spinning and subsequent pyrolysis of the precursor blend. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.