CPC H01M 4/386 (2013.01) [C01B 33/02 (2013.01); C22C 24/00 (2013.01); H01B 1/04 (2013.01); H01M 4/381 (2013.01); H01M 10/0525 (2013.01); C01P 2002/54 (2013.01); C01P 2002/72 (2013.01); C01P 2006/14 (2013.01); C01P 2006/16 (2013.01); C01P 2006/40 (2013.01); H01M 2004/027 (2013.01)] | 3 Claims |
1. A negative electrode active material comprising a silicon material in which silicon clathrate II represented by composition formula NaxSi136 (0≤x≤10) is contained and a volume of a pore having a diameter of not greater than 100 nm is not less than 0.025 cm3/g.
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