Abstract A novel 3D composite cathode structure, comprised of MnCr2O4 spinel-based nanowires, is hereby presented. The reagentless self-seeded spinel-based nanowires are grown using an extremely simple, one-step, growth process that is comprised of 5% hydrogen in nitrogen at atmospheric pressure, under 1100 °C , without any external catalyst or reagent. This simple one-step process allows the density-controlled growth of highly crystalline spinel nanowires directly from common stainless steel mesh substrates, which acts both as reagents source and as a current collector. Electrochemical measurements show that this cathode exhibits high capacity (>230 mA h/g), stable cyclability (>370 cycles), high coulombic efficiency (>99%) and high rate performance (>2C). The novel 3D composite cathode structure exhibits several major advantages over conventional 2D cathodes, both in terms of the synthesis process and cost-effectiveness, and in terms of electrochemical performance enhancement possibilities.