Negative electrode active material, method for manufacturing same, and lithium secondary battery

Patent metadata

Field	Value
Publication number	US-2016285091-A1
Application number	US-201314442141-A
Country	US
Kind code	A1
Filing date	Oct 28, 2013
Priority date	Nov 13, 2012
Publication date	Sep 29, 2016
Grant date	—

Abstract

A negative electrode active material comprising silicon oxide satisfying the following Equation 1 and Equation 2 when solid state NMR ( 29 Si-DDMAS) of silicon is measured for the silicon oxide after performing charging at least once is excellent in the performance as a negative electrode active material for a lithium secondary battery;
0.42≦ S 1/( S 1+ S 2+ S 3)≦0.55  (Equation 1)

0.21≦ S 3/( S 1+ S 2+ S 3)≦0.26,  (Equation 2)

in which S1 is a sum of peak areas of a group of signals assigned to Si having a Si—Si bond and having peaks at 0 to −15 ppm, −55 ppm, −84 ppm and −88 ppm, S2 is a sum of peak areas of a group of signals assigned to Si having a Si(OH) 4-n (OSi) n (n=3, 4) structure and having peaks at −100 ppm and −120 ppm, and S3 is a sum of peak areas of a group of signals assigned to Si having a Si(OLi) 4-n (OSi) n (n=0, 1, 2, 3) structure and having peaks at −66 ppm, −74 ppm, −85 ppm and −96 ppm.

First claim

1 . A negative electrode active material comprising silicon oxide which satisfies the following Equation 1 and Equation 2 when solid state NMR ( 29 Si-DDMAS) of silicon is measured for the silicon oxide after performing charging at least once,
0.42≦ S 1/( S 1+ S 2+ S 3)≦0.55  (Equation 1)
0.21≦ S 3/( S 1+ S 2+ S 3)≦0.26,  (Equation 2)
in which S1 is a sum of peak areas of a group of signals assigned to Si having a Si—Si bond and having peaks at 0 to −15 ppm, −55 ppm, −84 ppm and −88 ppm, S2 is a sum of peak areas of a group of signals assigned to Si having a Si(OH) 4-n (OSi) n (n=3, 4) structure and having peaks at −100 ppm and −120 ppm, and S3 is a sum of peak areas of a group of signals assigned to Si having a Si(OLi) 4-n (OSi) n (n=0, 1, 2, 3) structure and having peaks at −66 ppm, −74 ppm, −85 ppm and −96 ppm.

2 . The negative electrode active material according to claim 1 , wherein conditions of the Equation 1 and Equation 2 are satisfied after performing the charging once.

3 . The negative electrode active material according to claim 1 , wherein the negative electrode active material contains silicon oxide pre-doped with lithium, and conditions of the Equation 1 and Equation 2 are satisfied after performing the charging at least once.

4 . The negative electrode active material according to claim 3 , wherein the silicon oxide is pre-doped with lithium by employing at least one of (i) a method utilizing thermal diffusion of lithium and (ii) a method of electrochemically doping lithium.

5 . The negative electrode active material according to claim 4 , wherein after performing pre-doping by (i) utilizing thermal diffusion of lithium, the pre-doping is performed by (ii) the method of electrochemically doping lithium.

6 . A lithium secondary battery comprising a negative electrode comprising a negative electrode active material according to claim 1 , a binder and a collector, a positive electrode and an electrolyte.

7 . A method for manufacturing a negative electrode active material comprising silicon oxide, comprising a step of doping the silicon oxide with lithium,
wherein lithium is doped in the step of doping the silicon oxide with lithium so as to satisfies the following Equation 1 and Equation 2 when solid state NMR ( 29 Si-DDMAS) of silicon is measured for the silicon oxide after performing charging at least once,
0.42≦ S 1/( S 1+ S 2+ S 3)≦0.55  (Equation 1)

0.21≦ S 3/( S 1+ S 2+ S 3)≦0.26,  (Equation 2)

in which S1 is a sum of peak areas of a group of signals assigned to Si having a Si—Si bond and having peaks at 0 to −15 ppm, −55 ppm, −84 ppm and −88 ppm, S2 is a sum of peak areas of a group of signals assigned to Si having a Si(OH) 4-n (OSi) n (n=3, 4) structure and having peaks at −100 ppm and −120 ppm, and S3 is a sum of peak areas of a group of signals assigned to Si having a Si(OLi) 4-n (OSi) n (n=0, 1, 2, 3) structure and having peaks at −66 ppm, −74 ppm, −85 ppm and −96 ppm.

8 . The method for manufacturing a negative electrode active material according to claim 7 , wherein the silicon oxide is doped with lithium by employing at least one of (i) a method utilizing thermal diffusion of lithium and (ii) a method of electrochemically doping lithium.

9 . The method for manufacturing a negative electrode active material according to claim 8 , wherein the silicon oxide is doped with lithium by (i) the method utilizing thermal diffusion of lithium and thereafter doped with lithium by (ii) the method of electrochemically doping lithium.

10 . An evaluation method for a negative electrode active material comprising silicon oxide, the method comprising:
measuring solid state NMR ( 29 Si-DDMAS) of silicon for the silicon oxide after performing charging at least once, and selecting the negative electrode active material depending on whether the following Equation 1 and Equation 2 is satisfied,
0.42≦ S 1/( S 1+ S 2+ S 3)≦0.55  (Equation 1)

0.21≦ S 3/( S 1+ S 2+ S 3)≦0.26,  (Equation 2)

in which S1 is a sum of peak areas of a group of signals assigned to Si having a Si—Si bond and having peaks at 0 to −15 ppm, −55 ppm, −84 ppm and −88 ppm, S2 is a sum of peak areas of a group of signals assigned to Si having a Si(OH) 4-n (OSi) n (n=3, 4) structure and having peaks at −100 ppm and −120 ppm, and S3 is a sum of peak areas of a group of signals assigned to Si having a Si(OLi) 4-n (OSi) n (n=0, 1, 2, 3) structure and having peaks at −66 ppm, −74 ppm, −85 ppm and −96 ppm.

Assignees

• Nec Corp

Inventors

• Iriyama Jiro
• Kawasaki Daisuke
• Fujii Emiko
• Serizawa Shin
• Takahashi Hiroo

Classifications

• H01M4/0459

  Electrochemical doping, intercalation, occlusion or alloying · CPC title

• H01M4/485 Primary

  of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy (H01M4/505, H01M4/525 take precedence) · CPC title

• H01M2004/027

  Negative electrodes · CPC title

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• H01M4/0445

  Forming after manufacture of the electrode, e.g. first charge, cycling · CPC title