CN114361393B

CN114361393B - Method for preparing self-supporting silicon negative electrode and application of self-supporting silicon negative electrode in lithium/sodium battery

Info

Publication number: CN114361393B
Application number: CN202210017003.0A
Authority: CN
Inventors: 冯金奎; 安永灵; 田园
Original assignee: Shandong University
Current assignee: Shandong University
Priority date: 2022-01-07
Filing date: 2022-01-07
Publication date: 2023-08-15
Anticipated expiration: 2042-01-07
Also published as: CN114361393A

Abstract

The application belongs to the technical field of materials, and particularly relates to a method for preparing a self-supporting silicon negative electrode and application of the self-supporting silicon negative electrode in a lithium/sodium battery. The method comprises the following steps: and depositing metallic lithium on a current collector, then placing the current collector in a silicon tetrachloride/silicon tetrabromide solution, obtaining a silicon material on the surface of the current collector, and drying to obtain the self-supporting silicon anode. The silicon-based material is obtained by an in-situ reduction method, is uniform and is of a self-supporting structure, the use of conductive agents and binders can be avoided, the working procedures are reduced, the cost is reduced, and the energy density of the battery is improved. By adjusting the deposition amount of lithium metal, the amount of silicon can be controlled. By adjusting the time of substitution, the relative amounts of lithium and silicon in the product can be adjusted, thereby controlling its conductivity.

Description

Method for preparing self-supporting silicon negative electrode and application of self-supporting silicon negative electrode in lithium/sodium battery

Technical Field

The application belongs to the technical field of energy storage, and particularly relates to a simple method for preparing a self-supporting silicon anode and application thereof.

Background

The disclosure of this background section is only intended to increase the understanding of the general background of the application and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art already known to those of ordinary skill in the art.

The silicon negative electrode has the advantages of high lithium storage theoretical specific capacity, low working voltage, rich energy storage, no toxicity and the like. However, several problems limit its further commercial development. (1) The preparation process is complex, the required equipment is complex, the yield is low, and the cost is high. (2) Large volume expansion is generated in the circulation process, the structure of the material is destroyed, and the electrode material is pulverized and falls off, so that the circulation performance is poor. (3) silicon has poor conductivity and thus has poor rate performance.

The inventors found that: the defects of complex preparation, high cost, poor conductivity and the like in the prior art are that the development of a simple method for preparing the silicon negative electrode is important.

Disclosure of Invention

Aiming at the defects of the prior art, the application provides a simple method for preparing a self-supporting silicon anode.

In order to achieve the technical purpose, the application adopts the following technical scheme:

in a first aspect of the present application, there is provided a method for simply preparing a self-supporting silicon anode, comprising:

depositing metallic lithium on a current collector, then placing the current collector in silicon tetrachloride or silicon tetrabromide solution for substitution reaction, and obtaining a silicon material on the surface of the current collector;

and drying the silicon material to obtain the silicon material.

In a second aspect of the application, a self-supporting silicon electrode prepared by the above method is provided.

In a third aspect of the present application, a lithium ion battery is provided, the negative electrode being the self-supporting silicon electrode described above.

In a fourth aspect of the application, a sodium ion battery is provided, the negative electrode being the self-supporting silicon electrode described above.

The application has the beneficial effects that:

(1) The silicon-based material is obtained by an in-situ reduction method, is uniform and is of a self-supporting structure, the use of conductive agents and binders can be avoided, the working procedures are reduced, the cost is reduced, and the energy density of the battery is improved.

(2) By adjusting the deposition amount of lithium metal, the amount of silicon can be controlled.

(3) By adjusting the time of substitution, the relative amounts of lithium and silicon in the product can be adjusted, thereby controlling its conductivity.

(4) The method has the advantages of simplicity, low cost, universality and easiness in large-scale production.

(5) The research finds that: compared with the silicon material prepared by adopting an in-situ growth method, an electrodeposition method, a template method and an etching method, the silicon material prepared by the replacement of metallic lithium not only maintains better electrochemical performance, but also has more uniform silicon particles in the obtained product. In addition, the bonding force between silicon and the current collector is stronger.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the application.

Fig. 1 is an XRD pattern of the silicon material prepared in example 1.

Detailed Description

It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the application. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

As described in the background art, the present application provides a highly conductive carbon material, which addresses the deficiencies of the prior art.

The method comprises the following steps:

and depositing metallic lithium on a current collector, then placing the current collector in a silicon tetrachloride/silicon tetrabromide solution, obtaining a silicon material on the surface of the current collector, and drying to obtain the self-supporting silicon anode.

The deposition mode of the metallic lithium is electrodeposition or fused deposition.

The current collector is copper, aluminum, carbon cloth, MXene and the like.

In a third aspect of the application, there is provided an application of the silicon electrode in a lithium ion battery.

In a fourth aspect of the application, there is provided the use of the silicon electrode described above in a sodium ion battery.

The application will now be described in further detail with reference to the following specific examples, which should be construed as illustrative rather than limiting.

In the following examples, the copper-based current collector was a double-light copper foil 200X 0.012mm.1Kg/roll.

Example 1

A self-supporting silicon material:

deposition of metallic lithium:

assembling a half cell, wherein a copper foil is used as a working electrode, a lithium sheet is used as a counter electrode and a reference electrode, the electrolyte is 1M LiPF6+EC/DEC, and the deposition parameter is 1mA cm ^-1 The time was 2h.

Substitution reaction: and (3) putting the obtained copper-based current collector into silicon tetrachloride, soaking for 30min, taking out, and drying to prepare the self-supporting silicon electrode, wherein the XRD pattern of the self-supporting silicon electrode is shown in figure 1.

Performance test: the silicon is adopted as a working electrode, a lithium sheet is adopted as a counter electrode and a reference electrode, and 1M LiPF is adopted as electrolyte ₆ +EC/DEC/10% FEC, current density 500mAg ^-1 The voltage interval is 0.01V ^-3 V, the capacity retention rate of the assembled battery after 100 weeks circulation is 86.8%, which proves that the silicon electrode has good performance.

Example 2

A self-supporting silicon material:

deposition of metallic lithium:

assembling a half cell, wherein a copper foil is used as a working electrode, a lithium sheet is used as a counter electrode and a reference electrode, the electrolyte is 1M LiPF6+EC/DEC, and the deposition parameter is 2mA cm ^-1 The time was 0.5h.

Substitution reaction: and (3) putting the obtained copper-based current collector into silicon tetrachloride solution, soaking for 35min, taking out, and drying to prepare the self-supporting silicon electrode.

Example 3

A self-supporting silicon material:

deposition of metallic lithium:

assembling a half cell, wherein a copper foil is used as a working electrode, a lithium sheet is used as a counter electrode and a reference electrode, the electrolyte is 1M LiPF6+EC/DEC, and the deposition parameter is 10mA cm ^-1 The time was 0.02h.

Substitution reaction: and (3) putting the obtained copper-based current collector into a silicon tetrachloride solution, soaking for 20min, taking out, and drying to prepare the self-supporting silicon electrode.

Example 4

A self-supporting silicon material:

deposition of metallic lithium:

assembling a half cell, wherein a copper foil is used as a working electrode, a lithium sheet is used as a counter electrode and a reference electrode, the electrolyte is 1M LiPF6+EC/DEC, and the deposition parameter is 5mA cm ^-1 The time was 0.2h.

Substitution reaction: and (3) putting the obtained copper-based current collector into silicon tetrachloride solution, soaking for 15min, taking out, and drying to prepare the self-supporting silicon electrode.

Finally, it should be noted that the above-mentioned embodiments are only preferred embodiments of the present application, and the present application is not limited to the above-mentioned embodiments, but may be modified or substituted for some of them by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method of making a self-supporting silicon anode comprising:

drying the silicon material to obtain the silicon material;

the soaking time of the current collector deposited with the metallic lithium in the silicon tetrachloride/silicon tetrabromide solution is 15-35 min.

2. The method of making a self-supporting silicon anode according to claim 1, wherein the current collector is copper, aluminum, carbon cloth, or MXene.

3. The method of preparing a self-supporting silicon anode according to claim 1, wherein the deposition is electrodeposition or fused deposition.

4. The method of preparing a self-supporting silicon anode according to claim 3, wherein the electrodeposition uses copper foil as a working electrode, and lithium sheets as a counter electrode and a reference electrode.

5. A method of preparing a self-supporting silicon anode according to claim 3, wherein the electrolyte is lipf6+ec/DEC.

6. The method for preparing a self-supporting silicon anode according to claim 3, wherein the deposition parameter is 1 to 10mAcm ^-1 The time is 0.2-2 h.

7. A self-supporting silicon electrode made by the method of any one of claims 1-6.

8. A lithium ion battery characterized in that the negative electrode is the self-supporting silicon electrode of claim 7.

9. A sodium ion battery characterized in that the negative electrode is the self-supporting silicon electrode of claim 7.