Li-doped SiO-negative active material (LixSiO) has been successfully synthesized by chemical method with immersion in Li-organic complex solution obtained by dissolving naphthalene and metallic Li into butyl methyl ether (BME) solvent. The rest potential of resultant LixSiO electrode drastically shifts to less noble value at the beginning of immersion and tends to be stable at around 0.21 V versus Li/Li+, which means the progress of Li-doping into SiO-negative active material. Furthermore, this chemical Li-doping process proceeds by the catalysis function of naphthalene and leads to reduce the irreversible capacity of SiO-negative electrode caused by consumption of Li sources provided from positive electrode. (c) 2005 Elsevier B.V. All rights reserved.