US 12,424,620 B2
Negative electrode active material, negative electrode and method for producing them
Takakazu Hirose, Annaka (JP); Reiko Sakai, Takasaki (JP); Yusuke Osawa, Annaka (JP); Takumi Matsuno, Annaka (JP); Kohta Takahashi, Takasaki (JP); Katsunori Nishiura, Chiba (JP); and Nan Fang, Ichihara (JP)
Assigned to SHIN-ETSU CHEMICAL CO., LTD., Tokyo (JP)
Appl. No. 17/642,302
Filed by SHIN-ETSU CHEMICAL CO., LTD., Tokyo (JP)
PCT Filed Jul. 16, 2020, PCT No. PCT/JP2020/027582
§ 371(c)(1), (2) Date Mar. 11, 2022,
PCT Pub. No. WO2021/053951, PCT Pub. Date Mar. 25, 2021.
Claims priority of application No. 2019-169865 (JP), filed on Sep. 18, 2019.
Prior Publication US 2022/0336800 A1, Oct. 20, 2022
Int. Cl. H01M 4/48 (2010.01); H01M 4/04 (2006.01); H01M 4/02 (2006.01)
CPC H01M 4/48 (2013.01) [H01M 4/0402 (2013.01); H01M 2004/021 (2013.01); H01M 2004/027 (2013.01)] 8 Claims
OG exemplary drawing
 
1. A negative electrode active material comprising negative electrode active material particles,
wherein the negative electrode active material particles contain silicon compound particles containing a silicon compound,
the silicon compound particles contain Li2SiO3,
at least a part of a surface of the silicon compound particles is covered with a carbon layer, and
a surface layer of the negative electrode active material particles contains a substance having a carboxylic acid structure,
wherein the negative electrode active material particles are that in which a negative fragment derived from a carboxylic acid structure is detected by measurement by TOF-SIMS,
wherein a spectral intensity of Six+ (0<x<4) of a negative electrode containing the negative electrode active material after charging is higher than that of the negative electrode after discharging in a spectrum of K absorption edge XANES of Si obtained from the XAFS measurement of the negative electrode taken out from a charged secondary battery, and the negative electrode taken out from the charged secondary battery after complete discharge, and
wherein the XANES spectrum of the negative electrode after the charge spectral intensity of Six+ (2≤x<4) is higher than spectral intensity of Six+ (0<x<2).