A thermoelectric conversion material includes Mg.sub.2Si.sub.xSn.sub.1−x (where 0.3≤X≤1) and a boride containing one or two or more metals selected from titanium, zirconium, and hafnium. Further, it is preferable that the boride is one or two or more selected from TiB.sub.2, ZrB.sub.2, and HfB.sub.2.

The present invention provides a thermoelectric material excellent in heat resistance with less degradation of thermoelectric characteristics even in a high temperature environment. The thermoelectric material comprises a compound represented by a chemical formula Mg.sub.2Si.sub.1-xSn.sub.x (0<x<1) wherein at least one of the Si site and the Sn site of the compound is replaced with at least one of Sb and Bi, and an added Fe.

A metal-Si based powder contains a metal-Si based particle including a plurality of crystal phase grains. The crystal phase grains include a crystal phase containing a compound of a metal and Si. The crystal phase grains have an average grain size of, for example, 20 μm or less. The metal-Si based particle has an average particle size of, for example, 5 to 100 μm.

A main object of the present disclosure is to provide an active material whose volume variation due to charge and discharge is small. The present disclosure achieves the object by providing an active material comprising a primary particle including at least one crystal phase of a Type I silicon clathrate and a Type II silicon clathrate, and the primary particle includes a void inside thereof.

A main object of the present disclosure is to provide an active material whose volume variation due to charge and discharge is small. The present disclosure achieves the object by providing an active material comprising a primary particle including at least one crystal phase of a Type I silicon clathrate and a Type II silicon clathrate, and the primary particle includes a void inside thereof.

Silicon materials suitable for use as an anode material and associated method of production are disclosed herein. In one embodiment, a silicon material includes crystalline silicon in a matrix and macro-scale pores distributed in the matrix of the crystalline silicon. The macro-scale pores can have a size greater than 100 nanometers, and surfaces of crystalline silicon in the macro-scale pores are coated with carbon.

Silicon materials suitable for use as an anode material and associated method of production are disclosed herein. In one embodiment, a silicon material includes crystalline silicon in a matrix and macro-scale pores distributed in the matrix of the crystalline silicon. The macro-scale pores can have a size greater than 100 nanometers, and surfaces of crystalline silicon in the macro-scale pores are coated with carbon.

A main object of the present disclosure is to provide an active material wherein an expansion upon intercalation of a metal ion such as a Li ion is suppressed. The present disclosure achieves the object by providing an active material comprising a silicon clathrate type crystal phase, and the active material includes a Na element, a Si element and a M element that is a metal element with an ion radius larger than the Si element, and a proportion of the M element to a total of the Si element and the M element is 0.1 atm % or more and 5 atm % or less.

A main object of the present disclosure is to provide an active material wherein an expansion upon intercalation of a metal ion such as a Li ion is suppressed. The present disclosure achieves the object by providing an active material comprising a silicon clathrate type crystal phase, and the active material includes a Na element, a Si element and a M element that is a metal element with an ion radius larger than the Si element, and a proportion of the M element to a total of the Si element and the M element is 0.1 atm % or more and 5 atm % or less.

A main object of the present disclosure is to provide an active material wherein an expansion upon intercalation of a metal ion such as a Li ion is suppressed. The present disclosure achieves the object by providing an active material comprising a silicon clathrate type crystal phase, and the active material includes a Na element, a Si element and a M element that is a metal element with an ion radius larger than the Si element, and a proportion of the M element to a total of the Si element and the M element is 0.1 atm % or more and 5 atm % or less.