Abstract: A negative electrode active material is composed of a silicon material coated with a carbon layer containing a Group 4 to 6 metal. A method for producing a negative electrode active material includes a step of decomposing a compound containing the Group 4 to 6 metal and a carbon source by heating in the presence of a silicon material, the compound, and the carbon source.

Abstract: A method for producing a silicon material, the method including: a step of heating CaSi2 powder in a range of 400 to 1000° C.; a step of reacting acid with the CaSi2 powder having been subjected to the step of heating CaSi2 powder in a range of 400 to 1000° C., to obtain a layered silicon compound; and a step of heating the layered silicon compound at not less than 300° C.

Abstract: A production process for carbon-coated silicon material includes the step of: heating CaSi2 and a halogen-containing polymer at a temperature being a carbonization temperature or more of the halogen-containing polymer in a state where the CaSi2 and the halogen-containing polymer coexist.

Abstract: Cycle characteristics of a nonaqueous secondary battery are to be improved. An active material including: a first active material that contains a nano silicon produced by heating a layered polysilane represented by a composition formula (SiH)n and having a structure in which multiple six-membered rings formed from silicon atoms are connected; and a second active material that contains a graphite, is used in a negative electrode. With this, expansion and contraction due to stress during charging and discharging can be mitigated, and thereby cycle characteristics improve.

Abstract: A nano silicon material having reduced amounts of oxygen (O) and chlorine (Cl) contained therein is provided. The nano silicon material contains fluorine (F) and nano-sized silicon crystallites. Generation of a layer in which oxygen (O) and chlorine (Cl) are present is suppressed due to the presence of fluorine (F), so that a decrease in the moving speed of lithium ions is suppressed. In addition, due to the presence of fluorine (F), the concentrations of oxygen (O) and chlorine (Cl) are reduced, so that reaction thereof with lithium ions is suppressed.

Abstract: Provided is a method for producing a CaSi2-containing composition, the method including: a molten metal step of adding Ca and/or M (M is at least one element selected from elements of groups 3 to 9) to a CaSi2-containing composition containing crystalline silicon to prepare a molten metal containing Ca, M and Si that satisfy the following condition: when a molar ratio of Ca, M and Si is x:y:z (x+y+z=100), x, y and z satisfy 23<x?100/3, 0<y<10 and 64<z?200/3, respectively; and a cooling step of cooling the molten metal to obtain a CaSi2-containing composition containing a reduced amount of crystalline silicon.

Abstract: A silicon material useful as a negative electrode active material is provided. The silicon material has an Si/O atom ratio within a range of greater than 1/0.5 and not greater than 1/0.1 and a band gap within a range of greater than 1.1 eV and not greater than 2.1 eV. A secondary battery in which this silicon material is used as a negative electrode active material has long life.

Abstract: A silicon material useful as a negative electrode active material is provided. The silicon material has a band gap within a range of greater than 1.1 eV and not greater than 1.7 eV. A secondary battery in which this silicon material is used as a negative electrode active material has improved initial efficiency.

Abstract: A negative electrode active material is composed of a silicon material coated with a carbon layer containing a Group 4 to 6 metal. A method for producing a negative electrode active material includes a step of decomposing a compound containing the Group 4 to 6 metal and a carbon source by heating in the presence of a silicon material, the compound, and the carbon source.

Abstract: A method for producing a silicon material, the method including: a step of heating CaSi2 powder in a range of 400 to 1000° C.; a step of reacting acid with the CaSi2 powder having been subjected to the step of heating CaSi2 powder in a range of 400 to 1000° C., to obtain a layered silicon compound; and a step of heating the layered silicon compound at not less than 300° C.

Abstract: Provided is a method for producing a silicon material, the method including: a molten metal preparing step of preparing Ca-x at % Si alloy (42?x?75) molten metal; a solidifying step of cooling the molten metal by a rapid cooling device to solidify the Ca-x at % Si alloy; a synthesizing step of reacting the solidified Ca-x at % Si alloy with acid to obtain a layered silicon compound; and a heating step of heating the layered silicon compound at not less than 300° C.

Abstract: Provided is a method for producing a CaSi2-containing composition, the method including: a molten metal step of adding Ca and/or M (M is at least one element selected from elements of groups 3 to 9) to a CaSi2-containing composition containing crystalline silicon to prepare a molten metal containing Ca, M and Si that satisfy the following condition: when a molar ratio of Ca, M and Si is x:y:z (x+y+z=100), x, y and z satisfy 23<x?100/3, 0<y<10 and 64<z?200/3, respectively; and a cooling step of cooling the molten metal to obtain a CaSi2-containing composition containing a reduced amount of crystalline silicon.

Abstract: A production process for carbon-coated silicon material includes the step of: heating CaSi2 and a halogen-containing polymer at a temperature being a carbonization temperature or more of the halogen-containing polymer in a state where the CaSi2 and the halogen-containing polymer coexist.

Abstract: A production process for carbon-coated silicon material includes the steps of: a lamellar-silicon-compound production step of reacting CaSi2 with an acid to turn the CaSi2 into a lamellar silicon compound; a silicon-material production step of heating the lamellar silicon compound at 300° C. or more to turn the lamellar silicon compound into a silicon material; a coating step of coating the silicon material with carbon; and a washing step of washing the silicon material, or another silicon material undergone the coating step, with a solvent of which the relative permittivity is 5 or more.

Abstract: A silicon material useful as a negative electrode active material is provided. The silicon material has a band gap within a range of greater than 1.1 eV and not greater than 1.7 eV. A secondary battery in which this silicon material is used as a negative electrode active material has improved initial efficiency.

Abstract: A negative electrode active material having improved electron conductivity is provided. A reaction between an acid and a copper-containing calcium silicide represented by CaCuxSiy is caused, and a heat treatment is performed in a non-oxidizing atmosphere on the reaction product, to obtain a copper-containing silicon material. The copper-containing silicon material contains Si and copper in an amorphous phase, and fine copper silicide is uniformly deposited within the amorphous phase. Thus, electron conductivity improves. Therefore, a secondary battery in which the negative electrode active material is used as a negative electrode has improved rate characteristics and also has an increased charge/discharge capacity.

Abstract: A nano silicon material having reduced amounts of oxygen (O) and chlorine (Cl) contained therein is provided. The nano silicon material contains fluorine (F) and nano-sized silicon crystallites. Generation of a layer in which oxygen (O) and chlorine (Cl) are present is suppressed due to the presence of fluorine (F), so that a decrease in the moving speed of lithium ions is suppressed. In addition, due to the presence of fluorine (F), the concentrations of oxygen (O) and chlorine (Cl) are reduced, so that reaction thereof with lithium ions is suppressed.

Abstract: A silicon material useful as a negative electrode active material is provided. The silicon material has an Si/O atom ratio within a range of greater than 1/0.5 and not greater than 1/0.1 and a band gap within a range of greater than 1.1 eV and not greater than 2.1 eV. A secondary battery in which this silicon material is used as a negative electrode active material has long life.

Abstract: Cycle characteristics of a nonaqueous secondary battery are to be improved. An active material including: a first active material that contains a nano silicon produced by heating a layered polysilane represented by a composition formula (SiH)n and having a structure in which multiple six-membered rings formed from silicon atoms are connected; and a second active material that contains a graphite, is used in a negative electrode. With this, expansion and contraction due to stress during charging and discharging can be mitigated, and thereby cycle characteristics improve.