Solid-state battery negative electrode material, preparation method thereof and solid-state battery

Abstract

The invention discloses a negative electrode material of a solid-state battery, a preparation method of the negative electrode material and the solid-state battery. The negative electrode material of the solid-state battery is composed of a silicon-carbon base material and a conductive coating layer coating the periphery of the silicon-carbon base material, the conductive coating layer is formed by compounding agarose and m-hydroxybenzyl chloride. Agarose and m-hydroxybenzyl chloride are selected to be compounded according to a certain proportion to serve as a coating layer of the solid-state battery negative electrode material, due to the synergistic effect of electron donating group hydroxyl and electron withdrawing group chlorine atoms, the ionic conductivity is improved, the content of all the components is optimized and adjusted, and the solid-state battery negative electrode material is obtained. And the first coulombic efficiency and the cycle performance of the solid-state battery negative electrode material are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of solid-state batteries, and in particular to a solid-state battery negative electrode material and a preparation method thereof, and a solid-state battery. Background Art

[0002] Solid-state battery is a new type of energy storage battery with solid positive electrode, negative electrode and electrolyte. It is different from traditional liquid electrolyte battery. Because the electrolyte of solid battery is non-volatile, non-corrosive and non-flammable, it has higher safety. In addition, solid-state battery also has the characteristics of long cycle life, high charging efficiency and high energy density. It is widely used in electric vehicles, electronic equipment and other high-end equipment. The negative electrode material of solid-state battery is often made of silicon-carbon material. The carbon encapsulation of silicon nanoparticles enhances the conductivity and cycle stability of the negative electrode material. However, the first coulomb efficiency and cycle performance of the negative electrode material of solid-state battery still need to be further improved. Summary of the invention

[0003] In view of this, the present invention provides a solid-state battery negative electrode material and a preparation method thereof and a solid-state battery to solve the problems raised in the above-mentioned background technology. By coating a new type of enhanced conductive material on the surface of the silicon-carbon material, the first coulombic efficiency and cycle performance of the solid-state battery negative electrode material are further improved.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] In a first aspect, the present invention discloses a solid-state battery negative electrode material, which is composed of a silicon-carbon substrate and a conductive coating layer coated on the periphery of the silicon-carbon substrate; the conductive coating layer is compounded by agarose and m-hydroxybenzyl chloride.

[0006] As a further solution of the present invention: the agarose and m-hydroxybenzyl chloride are compounded in a mass ratio of 1:9-9:1;

[0007] As a further embodiment of the present invention: the mass of the agarose is ≤ the mass of m-hydroxybenzyl chloride.

[0008] As a further solution of the present invention: the agarose and m-hydroxybenzyl chloride are compounded in a mass ratio of 1:3-4.

[0009] As a further solution of the present invention: the mass ratio of the silicon-carbon substrate to the conductive coating layer is 20:1-5.

[0010] As a further solution of the present invention: the mass ratio of the silicon-carbon substrate to the conductive coating layer is 20:2-4.

[0011] In a second aspect, the present invention discloses a method for preparing the above-mentioned solid-state battery negative electrode material, comprising the following steps:

[0012] The silicon-carbon substrate is evenly dispersed in a solvent, and then agarose and m-hydroxybenzyl chloride are added, mixed at 70-90° C. for 1-3 hours, and dried to obtain a solid-state battery negative electrode material.

[0013] As a further solution of the present invention: mixing is performed by ultrasonic mixing.

[0014] As a further embodiment of the present invention: the solvent includes at least one of dimethyl sulfoxide and acetonitrile.

[0015] As a further solution of the present invention: the mass ratio of the silicon-carbon substrate to the solvent is 2-4:25.

[0016] In a third aspect, the present invention discloses a solid-state battery, which includes the above-mentioned solid-state battery negative electrode material or the solid-state battery negative electrode material prepared by the above-mentioned preparation method.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention selects agarose and m-hydroxybenzyl chloride to be compounded in a certain ratio as a coating layer of a negative electrode material for a solid-state battery. Due to the synergistic effect of an electron-donating group hydroxyl and an electron-withdrawing group chlorine atom, the ionic conductivity is improved. Meanwhile, agarose and m-hydroxybenzyl chloride as the coating layer of the negative electrode material for the solid-state battery reduce the volume change of the negative electrode material. The first coulomb efficiency and cycle performance of the negative electrode material for the solid-state battery are improved by optimizing and adjusting the content of each component. DETAILED DESCRIPTION

[0019] For ease of understanding of the present invention, the present invention will be described more fully below in conjunction with specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly understood.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0021] The specific information of the raw materials used in the following examples and comparative examples is as follows:

[0022] The silicon carbon substrate is prepared according to the following method:

[0023] Add 100 parts of elemental silicon and 100 parts of asphalt into a mixer, stir at 500°C for 1.5 hours, cool to 25°C, and grind to a particle size of 2μm; add the grinded material into a rotary kiln, calcine at 800°C for 4 hours under a nitrogen atmosphere, switch the rotary kiln to an acetylene atmosphere, and calcine at 800°C for 1.5 hours; add the calcined material into a 5wt% sodium hydroxide solution, stir for 12 hours, filter and dry to obtain a silicon-carbon substrate.

[0024] Among them, the particle size of elemental silicon is 74μm; the asphalt is 70# asphalt.

[0025] All materials are commercially available conventional products.

[0026] It is to be understood that the above raw materials and reagents are only examples of some specific embodiments of the present invention, so that the technical solution of the present invention is clearer, and it does not mean that the present invention can only use the above reagents, and the specific scope in the claims shall prevail. In addition, the "parts" described in the examples and comparative examples, unless otherwise specified, refer to parts by weight.

[0027] Any range described in the present invention includes the end value and any numerical value between the end values ​​and any sub-range formed by the end value or any numerical value between the end values.

[0028] Example 1

[0029] 20 parts of silicon-carbon substrate were ultrasonically dispersed in 250 parts of solvent (dimethyl sulfoxide), 0.9 parts of agarose and 0.1 parts of m-hydroxybenzyl chloride were added, and ultrasonication was continued at 80° C. until the mixture was uniformly mixed, and then dried to obtain a solid-state battery negative electrode material.

[0030] Example 2

[0031] 40 parts of silicon-carbon substrate were ultrasonically dispersed in 250 parts of solvent (chloroform), 1 part of agarose and 9 parts of m-hydroxybenzyl chloride were added, and ultrasonication was continued at 80° C. until the mixture was uniformly mixed, and then dried to obtain a solid-state battery negative electrode material.

[0032] Example 3

[0033] 20 parts of silicon-carbon substrate were ultrasonically dispersed in 250 parts of solvent (dimethyl sulfoxide), 0.1 parts of agarose and 0.9 parts of m-hydroxybenzyl chloride were added, and ultrasonication was continued at 80° C. until the mixture was uniformly mixed, and then dried to obtain a solid-state battery negative electrode material.

[0034] Example 4

[0035] 20 parts of silicon-carbon substrate were ultrasonically dispersed in 250 parts of solvent (dimethyl sulfoxide), 0.5 parts of agarose and 0.5 parts of m-hydroxybenzyl chloride were added, and ultrasonication was continued at 80° C. until the mixture was uniformly mixed, and then dried to obtain a solid-state battery negative electrode material.

[0036] Example 5

[0037] 20 parts of silicon-carbon substrate were ultrasonically dispersed in 250 parts of solvent (dimethyl sulfoxide), 0.25 parts of agarose and 0.75 parts of m-hydroxybenzyl chloride were added, and ultrasonication was continued at 80° C. until the mixture was uniformly mixed, and then dried to obtain a solid-state battery negative electrode material.

[0038] Example 6

[0039] 20 parts of silicon-carbon substrate were ultrasonically dispersed in 250 parts of solvent (dimethyl sulfoxide), 0.2 parts of agarose and 0.8 parts of m-hydroxybenzyl chloride were added, and ultrasonication was continued at 80° C. until the mixture was uniformly mixed, and then dried to obtain a solid-state battery negative electrode material.

[0040] Example 7

[0041] 20 parts of silicon-carbon substrate were ultrasonically dispersed in 250 parts of solvent (dimethyl sulfoxide), 1 part of agarose and 4 parts of m-hydroxybenzyl chloride were added, and ultrasonication was continued at 80° C. until the mixture was uniformly mixed, and then dried to obtain a solid-state battery negative electrode material.

[0042] Example 8

[0043] 20 parts of silicon-carbon substrate were ultrasonically dispersed in 250 parts of solvent (dimethyl sulfoxide), 0.4 parts of agarose and 1.6 parts of m-hydroxybenzyl chloride were added, and ultrasonication was continued at 80° C. until the mixture was uniformly mixed, and then dried to obtain a solid-state battery negative electrode material.

[0044] Example 9

[0045] 20 parts of silicon-carbon substrate were ultrasonically dispersed in 250 parts of solvent (dimethyl sulfoxide), 0.8 parts of agarose and 3.2 parts of m-hydroxybenzyl chloride were added, and ultrasonication was continued at 80° C. until the mixture was uniformly mixed, and then dried to obtain a solid-state battery negative electrode material.

[0046] Comparative Example 1

[0047] 20 parts of silicon-carbon substrate were ultrasonically dispersed in 250 parts of solvent (dimethyl sulfoxide), 1 part of agarose was added, and ultrasonication was continued at 80° C. until the mixture was uniformly mixed, and then dried to obtain a solid-state battery negative electrode material.

[0048] Comparative Example 2

[0049] 20 parts of silicon-carbon substrate were ultrasonically dispersed in 250 parts of solvent (dimethyl sulfoxide), 0.9 parts of agarose and 0.1 parts of N-(2-methoxy-5-methylphenyl)-3-oxo-butyramide were added, and ultrasonication was continued at 80°C until the mixture was uniform, and then dried to obtain a solid-state battery negative electrode material.

[0050] Test example

[0051] Solid electrolyte Li6PS5Cl and nitrile rubber are dissolved in xylene in a mass ratio of 98:2 to prepare a solid electrolyte slurry; the solid electrolyte slurry is evenly coated on polyethylene terephthalate and dried to obtain a solid electrolyte membrane; the solid-state battery negative electrode material prepared in Example 1-9 and Comparative Example 1-2 is mixed with sodium carboxymethyl cellulose, conductive agent VGCF, solid electrolyte Li6PS5Cl, and double distilled water in a mass volume ratio of 77g:15g:4g:4g:220mL in turn, coated on one side of the copper foil, dried, and rolled to prepare a negative electrode sheet; LiCoO2, solid electrolyte Li6PS5Cl, nitrile rubber, and conductive agent VGCF are dissolved in xylene in a mass ratio of 85:13:1:1, and evenly coated on the positive electrode collector foil box, dried, cold pressed, and cut to obtain a positive electrode sheet; the solid electrolyte membrane is placed between the negative electrode sheet and the positive electrode sheet to fit tightly to obtain a solid-state battery. The first coulombic efficiency was tested (the charging and discharging voltage range was 0.01-2.0V, and the charging and discharging rate was 0.1C), and the cycle performance was tested at the same time (0.5C charging, 1C discharging, and 500 cycles). The results are shown in Table 1.

[0052] Table 1

[0053] project First coulombic efficiency (%) First reversible capacity (mAh / g) 500 times capacity retention rate (%) Example 1 97.11 2201.5 94.61 Example 2 97.03 2189.3 94.14 Example 3 97.43 2224.8 95.23 Example 4 98.22 2253.7 95.89 Example 5 98.75 2261.3 96.57 Example 6 99.12 2271.4 97.04 Example 7 99.54 2289.3 97.70 Example 8 99.89 2321.9 98.95 Example 9 99.76 2310.8 98.22 Comparative Example 1 96.10 2065.5 89.21 Comparative Example 2 96.98 2175.1 92.86

[0054] Compared with Comparative Examples 1-2, the solid-state battery negative electrode material prepared in Example 1 is a compound of agarose and m-hydroxybenzyl chloride. As a result, the first coulombic efficiency, the first reversible capacity and the 500-time capacity retention rate of Example 1 are higher than those of Comparative Examples 1-3, indicating that the compound use of agarose and m-hydroxybenzyl chloride synergistically improves the first coulombic efficiency and cycle performance of the solid-state battery negative electrode material.

[0055] Compared with Example 1, the mass of agarose in the solid-state battery negative electrode material prepared in Example 3-6 is ≤ the mass of m-hydroxybenzyl chloride. As a result, the first coulombic efficiency, the first reversible capacity and the 500-time capacity retention rate of Example 3-6 are higher than those in Example 1, indicating that the mass of agarose is ≤ the mass of m-hydroxybenzyl chloride, which further improves the first coulombic efficiency and cycle performance of the solid-state battery negative electrode material.

[0056] Compared with Example 3-4, the mass ratio of agarose and m-hydroxybenzyl chloride in the solid-state battery negative electrode material prepared in Example 5-6 is 1:3-4. As a result, the first coulombic efficiency, first reversible capacity and 500 times capacity retention rate of Example 5-6 are higher than those of Example 3-4, indicating that the mass ratio of agarose and m-hydroxybenzyl chloride is 1:3-4, which further improves the first coulombic efficiency and cycle performance of the solid-state battery negative electrode material.

[0057] Compared with Examples 6-7, the mass ratio of the silicon-carbon substrate and the coating layer in the solid-state battery negative electrode material prepared in Examples 8-9 is 20:2-4. As a result, the first coulombic efficiency, the first reversible capacity and the 100-time capacity retention rate of Examples 8-9 are higher than those of Examples 6-7, indicating that the mass ratio of the silicon-carbon substrate and the coating layer is 20:2-4, which further improves the first coulombic efficiency and cycle performance of the solid-state battery negative electrode material.

[0058] Although this specification is described according to implementation modes, not every implementation mode includes only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

[0059] Therefore, the above description is only a preferred embodiment of the present application and is not intended to limit the scope of implementation of the present application; that is, all equivalent changes made according to the scope of the claims of the present application are within the protection scope of the claims of the present application.

Claims

1. A solid-state battery negative electrode material, characterized in that: The invention is composed of a silicon-carbon substrate and a conductive coating layer coated on the periphery of the silicon-carbon substrate; the conductive coating layer is compounded by agarose and m-hydroxybenzyl chloride.

2. The solid-state battery negative electrode material according to claim 1, characterized in that: The agarose and m-hydroxybenzyl chloride are compounded in a mass ratio of 1:9-9:

1.

3. The solid-state battery negative electrode material according to claim 1, characterized in that: The mass of the agarose is ≤ the mass of m-hydroxybenzyl chloride.

4. The solid-state battery negative electrode material according to claim 1, characterized in that: The agarose and m-hydroxybenzyl chloride are compounded in a mass ratio of 1:3-4.

5. The solid-state battery negative electrode material according to claim 1, characterized in that: The mass ratio of the silicon-carbon substrate to the conductive coating layer is 20:1-5.

6. The solid-state battery negative electrode material according to claim 5, characterized in that: The mass ratio of the silicon-carbon substrate to the conductive coating layer is 20:2-4.

7. The method for preparing a solid-state battery negative electrode material according to any one of claims 1 to 6, characterized in that: The following steps are involved: The silicon-carbon substrate is evenly dispersed in a solvent, and then agarose and m-hydroxybenzyl chloride are added, mixed at 70-90° C. for 1-3 hours, and dried to obtain a solid-state battery negative electrode material.

8. The preparation method according to claim 7, characterized in that: The mixing was carried out by ultrasonic mixing.

9. The preparation method according to claim 7, characterized in that: The solvent includes at least one of dimethyl sulfoxide and acetonitrile.

10. The preparation method according to claim 7, characterized in that: The mass ratio of the silicon-carbon substrate to the solvent is 2-4:

25.

11. A solid-state battery, characterized in that: The solid-state battery negative electrode material comprises the solid-state battery negative electrode material according to any one of claims 1 to 6.