Negative electrode active material and lithium secondary battery including the same

Patent metadata

Field	Value
Publication number	US-10714741-B2
Application number	US-201715746661-A
Country	US
Kind code	B2
Filing date	Apr 20, 2017
Priority date	May 27, 2016
Publication date	Jul 14, 2020
Grant date	Jul 14, 2020

Abstract

The present invention relates to a silicon-carbon-based composite negative electrode active material, and a negative electrode for a secondary battery and a lithium secondary battery including the same, and particularly to a silicon-carbon-based composite negative electrode active material, in which physical stability is improved by including a carbon-based core capable of intercalating and deintercalating lithium ions and at least one silicon particle included in the carbon-based core and disposed in the form of being distributed in an outer portion of the carbon-based core, and a negative electrode for a secondary battery and a lithium secondary battery in which life characteristics are improved by including the same.

First claim

The invention claimed is:

1. A silicon-carbon-based composite negative electrode active material comprising:
a carbon-based core capable of intercalating and deintercalating lithium ions; and
at least one silicon particle included in the carbon-based core and disposed in a form of being distributed in an outer portion of the carbon-based core,
wherein the carbon-based core comprises a carbon material selected from the group consisting of natural graphite, artificial graphite, graphite, graphitizable carbon, non-graphitizable carbon, carbon black, and graphite oxide, or a mixture of two or more thereof, and
wherein the outer portion of the carbon-based core is a portion having a length of 10% to 50% of a total length from the center of the carbon-based core to a surface of the carbon-based core in a depth direction from the surface,
wherein the outer portion comprises at least some of the carbon material and the silicon particle(s),
wherein the carbon-based core has a concentration gradient in which porosity is gradually increased from a center at the core to the outer portion of the core.

2. The silicon-carbon-based composite negative electrode active material of claim 1 , wherein an average particle diameter of the carbon-based core is in a range of 5 μm to 30 μm.

3. The silicon-carbon-based composite negative electrode active material of claim 1 , wherein a pore ratio of the center of the carbon-based core:the outer portion of the carbon-based core is in a range of 10 vol %:20 vol % to 10 vol %:50 vol %.

4. The silicon-carbon-based composite negative electrode active material of claim 1 , wherein the at least one silicon particle disposed in the form of being distributed in the outer portion of the carbon-based core comprises a single material selected from the group consisting of a crystalline or amorphous silicon (Si) single phase, SiO x (0<x≤2), and a Si—Z alloy (where Z comprises alkali metal, alkaline earth metal, a Group 13 element, a Group 14 element, transition metal, a rare earth element, or a combination thereof, and is not Si), or a mixture of two or more thereof.

5. The silicon-carbon-based composite negative electrode active material of claim 1 , wherein the at least one silicon particle disposed in the form of being distributed in the outer portion of the carbon-based core has a diameter of 20 nm to 100 nm.

6. The silicon-carbon-based composite negative electrode active material of claim 1 , wherein the at least one silicon particle disposed in the form of being distributed in the outer portion of the carbon-based core is included in an amount of 5 wt % to 50 wt % based on a total amount of the negative electrode active material.

7. The silicon-carbon-based composite negative electrode active material of claim 1 , wherein the negative electrode active material further comprises at least one coating layer selected from the group consisting of a silicon-based coating layer and a carbon coating layer.

8. The silicon-carbon-based composite negative electrode active material of claim 7 , wherein the silicon-based coating layer is formed of a single material selected from the group consisting of a crystalline or amorphous silicon (Si) single phase, SiO x (0<x≤2), and a Si—Z alloy (where Z comprises alkali metal, alkaline earth metal, a Group 13 element, a Group 14 element, transition metal, a rare earth element, or a combination thereof, and is not Si), or a mixture of two or more thereof.

9. The silicon-carbon-based composite negative electrode active material of claim 7 , wherein the silicon-based coating layer is included in an amount of 0.01 wt % to 50 wt % based on a total weight of the negative electrode active material.

10. The silicon-carbon-based composite negative electrode active material of claim 7 , wherein the carbon coating layer is formed of amorphous carbon or a conductive polymer.

11. The silicon-carbon-based composite negative electrode active material of claim 7 , wherein the carbon coating layer is included in an amount of 0.01 wt % to 50 wt % based on a total weight of the negative electrode active material.

12. The silicon-carbon-based composite negative electrode active material of claim 1 , wherein the negative electrode active material has an average particle diameter (D50) of 6 μm to 55 μm.

13. The silicon-carbon-based composite negative electrode active material of claim 1 , wherein the negative electrode active material has a specific surface area (Brunauer-Emmett-Teller (BET)) of 0.5 m 2 /g to 20 m 2 /g.

14. A negative electrode comprising:
a current collector; and
an electrode material mixture layer including the silicon-carbon-based composite negative electrode active material of claim 1 which is formed on at least one surface of the current collector.

15. The negative electrode of claim 14 , wherein the electrode material mixture layer further comprises at least one additive selected from the group consisting of a conductive agent, a binder, and a filler.

16. A lithium secondary battery comprising:
a positive electrode;
a negative electrode;
a separator disposed between the positive electrode and the negative electrode; and
a non-aqueous electrolyte solution,
wherein the negative electrode comprises the negative electrode of claim 14 .

Assignees

• Lg Chemical Ltd

Inventors

• Choi Jung Hyun
• Lee Yong Ju
• Kim Eun Kyung

Classifications

• H01M4/366 Primary

  as layered products · CPC title

• H01M4/13

  Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof · CPC title

• H01M4/587

  for inserting or intercalating light metals · CPC title

• H01M4/386

  Silicon or alloys based on silicon · CPC title

• H01M4/62

  Selection of inactive substances as ingredients for active masses, e.g. binders, fillers · CPC title