A composite of copper grown on the surface of CNTs has been fabricated by a redox reaction between copper acetate and ethylene glycol for use as negative electrode at high currents in electrochemical energy storage. Subsequently, the as-prepared Cu/CNT composite was coated with carbon using glucose as carbon source. Structure, morphology and electrochemical performance of the composite were investigated by scanning electron microscopy, X-ray diffraction, XPS, and electrochemical measurements. The carbon coating effectively prevents the dissolution of copper carbonate complexes formed during the electrode reactions Cu-2(OH)(2)CO3 + 2e(-) (sic) Cu2O + OH- + HCO3- and Cu2O + H2O+ 2e(-) (sic) 2Cu + 2OH(-), increases the conductivity of the copper constituent in the negative electrode and protects this component against direct contact with the electrolyte solution during cycling. The C/Cu/CNTs composite exhibits higher capacity and better rate behavior as well as excellent cycling stability in 0.5 M K2CO3 aqueous solution than unsupported copper. (C) The Author(s) 2016. Published by ECS. All rights reserved.