NOVELTY - A silicon-containing material contains lithium, in which the lithium is doped and de-doped. A graph is drawn with respect to relationship between differential value (dQ/dV), which is obtained by differentiating charge/discharge capacity (Q) and voltage level (V) at working electrode with reference to the reference electrode, and voltage level (V), when charging and discharging are performed using tripolar cell consisting of working electrode containing silicon-containing material, reference electrode, counter electrode, and lithium-ion conductive electrolyte.    USE - Silicon-containing material is used as active material in manufacture of negative electrode of nonaqueous electrolyte secondary battery (all claimed). Uses include but are not limited to motor vehicle, electronic device, communication apparatus and electric vehicle.    ADVANTAGE - The secondary battery consisting of negative electrode containing the silicon-containing material has excellent cycle characteristics. The device using the secondary battery has excellent durability.    DETAILED DESCRIPTION - A silicon-containing material contains lithium, in which the lithium is doped and de-doped. The graph is drawn with respect to relationship between differential value (dQ/dV), which is obtained by differentiating charge/discharge capacity (Q) and voltage level (V) at working electrode with reference to the reference electrode, and voltage level (V), when charging and discharging are performed using tripolar cell consisting of working electrode containing silicon-containing material as active material, reference electrode made of metal lithium, counter electrode made of metal lithium, and lithium-ion conductive electrolyte. The silicon-containing material has ratio (B/A) of 2 or less, during discharging time when current flows through silicon-containing material in direction in which lithium is de-doped. The ratio is ratio of maximal value (B) of differential value (dQ/dV) between voltage levels of 420 mV and 520 mV with respect to maximal value (A) of differential value (dQ/dV) between voltage levels of 260 mV and 320 mV. INDEPENDENT CLAIMS are included for the following:    (1) negative electrode, which contains silicon-containing material as negative electrode active material;    (2) nonaqueous electrolyte secondary battery, which consists of positive electrode and negative electrode in which absorption and release is possible, and lithium ion electroconductivity electrolyte; and    (3) manufacture of negative electrode.