Negative electrode and method for manufacturing a negative electrode

Abstract

To provide: a negative electrode capable of significantly increasing capacity while maintaining battery characteristics; and a method for manufacturing such negative electrode.SOLUTION: A negative electrode includes: a negative electrode current collector having a roughened surface; and a negative electrode active material provided on the negative electrode current collector. The negative electrode active material comprises negative electrode active material particles including a compound of lithium, silicon, and oxygen. The negative electrode active material particles can be represented by SiOxLiy, and a value of x is 0.8 or more and 1.2 or less, and a value of y is 0.5 or more and 3.4 or less. The negative electrode active material has a multilayer structure composed of two or more layers. In Si2p bond energy obtained by X-ray photoelectron spectroscopy analysis of a layer interior in each layer of the negative electrode active material having the multilayer structure, intensity of a peak A acquired in the vicinity of 98 eV and intensity of a peak B acquired in the vicinity of 100.5 eV have a relation (intensity of peak A)≥(intensity of peak B).SELECTED DRAWING: Figure 1

Claims

1. A negative electrode current collector with a roughened surface, A negative electrode active material layer provided on the negative electrode current collector, A negative electrode having, The negative electrode active material layer includes negative electrode active material particles having a compound of lithium, silicon, and oxygen, and the negative electrode active material particles can be represented as SiOxLiy, where the value of x is 0.8 or more and 1.2 or less, and the value of y is 1.0 or more and 3.4 or less. The negative electrode active material layer has a multilayer structure consisting of two or more layers. A negative electrode characterized in that, in the Si2p bond energy obtained by X-ray photoelectron spectroscopy analysis of the interior of each layer in the negative electrode active material layer having the multilayer structure, the intensity of peak A obtained near 98 eV and the intensity of peak B obtained near 100.5 eV have the relationship (intensity of peak A) ≥ (intensity of peak B).

2. The negative electrode according to claim 1, characterized in that the intensity ratio of peak A to peak B obtained by X-ray photoelectron spectroscopy analysis of the interior of each layer of the negative electrode active material layer having the multilayer structure (intensity of peak A) / (intensity of peak B) is 1.1 or more and 1.6 or less.

3. The negative electrode according to claim 1, characterized in that the Li1s binding energy obtained by X-ray photoelectron spectroscopy analysis of the interior of each layer of the negative electrode active material layer having the multilayer structure has a peak obtained around 55 eV.

4. The negative electrode according to claim 1, characterized in that the O1s bond energy obtained by X-ray photoelectron spectroscopy analysis of the interior of each layer of the negative electrode active material layer having the multilayer structure has a peak obtained around 530 eV.

5. The negative electrode according to claim 1, characterized in that the negative electrode active material particles have a coating on their outermost surface consisting of at least one of Li carbonate, Li phosphate, Li fluoride, Al carbonate, Al phosphate, and Al fluoride.

6. The negative electrode active material particles are Li ４ SiO ４ 、Li ２ Si ２ O ５ 、Li ２ SiO ３ 及びLi ６ Si ２ O ７ The negative electrode according to claim 1, characterized in that it has at least one of them.

7. The negative electrode active material particles are Si １＋ ~Si ３＋ The negative electrode according to claim 1, characterized in that it has a silicon-lithium composite oxide.

8. The negative electrode active material particles are Si ４＋ The silicon-lithium composite oxide is Si １＋ ~Si ３＋ The negative electrode according to claim 1, characterized in that it is present in greater quantities than the silicon compound.

9. The negative electrode according to claim 1, characterized in that the negative electrode current collector has a surface surface with a ten-point average roughness Rz of 1.5 μm or more and 5.0 μm or less.

10. The negative electrode according to claim 1, characterized in that the negative electrode active material layer forms secondary particles, which are aggregates of the negative electrode active material particles, when the negative electrode active material particles are defined as primary particles, and the secondary particles are separated from each other in the in-plane direction.

11. A method for manufacturing a negative electrode according to any one of claims 1 to 10, A step of winding the negative electrode current collector onto a can roll having curvature, A step of vapor-depositing a film containing silicon and / or silicon monoxide, having a multilayer structure consisting of two or more layers, on the negative electrode current collector while the negative electrode current collector is running on the can roll, A step of blowing an oxygen-containing gas onto the film containing silicon and / or silicon monoxide to form a multilayer structure containing silicon dioxide on top of each layer, The process involves inserting and de-inserting lithium into the multilayer structure to form the negative electrode active material layer, A method for manufacturing a negative electrode, characterized by including the following:

12. A method for manufacturing a negative electrode according to claim 5, A step of winding the negative electrode current collector onto a can roll having curvature, A step of vapor-depositing a film containing silicon and / or silicon monoxide, having a multilayer structure consisting of two or more layers, on the negative electrode current collector while the negative electrode current collector is running on the can roll, A step of blowing an oxygen-containing gas onto the film containing silicon and / or silicon monoxide to form a multilayer structure containing silicon dioxide on top of each layer, The process involves inserting and de-inserting lithium into the multilayer structure to form the negative electrode active material layer, Includes, In the step of forming the multilayer structure, the multilayer structure is formed in which each layer contains silicon oxide containing silicon dioxide, A step of vapor-phase growing the negative electrode active material layer containing silicon oxide on the negative electrode current collector, The negative electrode active material layer is immersed in a lithium-containing solution, the silicon oxide is modified by electrochemical means to form a compound of lithium, silicon, and oxygen, and the coating is formed. A method for manufacturing a negative electrode, characterized by including the following:

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