A method for preparing anode material for all-solid-state battery

Abstract

The present invention discloses a method for preparing an all-solid-state battery anode material, belonging to the technical field of anode materials. The method first weighs a certain mass of red phosphorus and nano-silicon and mixes them by ball milling to obtain a mixture; then, the mixture is ball milled with cyclodextrin to obtain a phosphorus-silicon composite material; and finally, the phosphorus-silicon composite material is placed in a polyacyl chloride solution and reacted for a period of time, followed by treatment to obtain the all-solid-state battery anode material. The present invention further encapsulates the phosphorus-silicon composite material within a molecular cavity by reacting the cyclodextrin coated with the phosphorus-silicon mixture with the polyacyl chloride solution, thereby preventing the phosphorus-silicon from diffusing out of the molecular cavity under pressure.

Description

Technical Field

[0001] The present invention relates to the technical field of negative electrode materials, and in particular to a method for preparing a negative electrode material for an all-solid-state battery. Background Art

[0002] Lithium-ion batteries are widely used in numerous portable electronic devices due to their advantages, including high specific capacity, stable operating voltage, excellent safety, and lack of memory effect. With the rapid development of various electronic devices and electric vehicles, the demand for the energy and cycle life of lithium-ion batteries is increasing. Anode materials are a crucial component of batteries. Together with cathode materials, they determine key performance characteristics of lithium-ion batteries, including cycle life, capacity, and safety, making them a key research topic.

[0003] Currently, the specific capacity of commercial graphite-based negative electrode materials is low, only 372mAh / g, which limits the improvement of the overall capacity of lithium-ion batteries and can no longer meet market demand. Silicon materials have been proven to be an excellent alternative to graphite materials for high-energy lithium-ion batteries due to their excellent theoretical specific capacity of up to 4200mAh / g. However, there are still some difficulties in popularizing silicon-based materials, such as the large volume changes during cycling and the poor conductivity of silicon materials themselves. These defects have seriously hindered the application of silicon-based materials in lithium-ion batteries.

[0004] Therefore, it is urgent to propose a preparation method for all-solid-state battery negative electrode materials to solve the above problems. Summary of the Invention

[0005] The present invention discloses a method for preparing an all-solid-state battery negative electrode material, which can effectively solve at least one technical problem involved in the background technology.

[0006] To achieve the above object, the technical solution of the present invention is:

[0007] A method for preparing an all-solid-state battery negative electrode material comprises the following steps:

[0008] Step S1, weighing a certain amount of red phosphorus and nano-silicon and mixing them by ball milling to obtain a mixture;

[0009] Step S2, mixing the mixture with cyclodextrin by ball milling to obtain a phosphorus-silicon composite material;

[0010] Step S3: placing the phosphorus-silicon composite material into a polyacyl chloride solution to react for a period of time, and then treating it to obtain an all-solid-state battery negative electrode material.

[0011] As a preferred improvement of the present invention, the mass ratio of the red phosphorus to the nano-silicon is 5-8:5-2.

[0012] As a preferred improvement of the present invention, the mass proportion of cyclodextrin in the phosphorus silicon composite material is 0.5-5%.

[0013] As a preferred improvement of the present invention, in steps S1 and S2, the ball milling mixing rate is 200-500 rpm, the ball milling time is 15-60 min, and the ball-to-material ratio is 1:20-40.

[0014] As a preferred improvement of the present invention, in step S3, a polyacyl chloride monomer is dissolved in an organic solvent to obtain a polyacyl chloride solution; the polyacyl chloride monomer is an active acyl chloride monomer with difunctionality or higher, the organic solvent is any one of n-hexane and cyclohexane, and the concentration of the polyacyl chloride solution is 0.01-0.5 mol / L.

[0015] As a preferred improvement of the present invention, the polyacyl chloride monomer is any one of trimesoyl chloride and terephthaloyl chloride.

[0016] As a preferred improvement of the present invention, in step S3, the phosphorus silicon composite material is placed in a polyacyl chloride solution and reacted for 30 seconds to 2 minutes, and then dried at low temperature to obtain an all-solid-state battery negative electrode material.

[0017] As a preferred improvement of the present invention, in step S3, the phosphorus silicon composite material is placed in a polyacyl chloride solution and the reaction temperature is 20-60°C.

[0018] The beneficial effects of the present invention are as follows:

[0019] 1. The present invention mixes red phosphorus and nano-silicon and reacts the mixture with cyclodextrin. By utilizing the hollow structure of cyclodextrin, the nano-scale phosphorus-silicon mixture is bound within its molecular cavities, thereby limiting the expansion of the negative electrode.

[0020] 2. The present invention further encapsulates the phosphorus-silicon composite material inside the molecular cavity by reacting the phosphorus-silicon composite material, i.e., cyclodextrin coated with the phosphorus-silicon mixture, with a polyacyl chloride solution, thereby preventing the phosphorus-silicon from diffusing out of the molecular cavity under pressure. DETAILED DESCRIPTION

[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0022] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship and movement status of the various components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0023] In addition, the terms "first," "second," and so on, used in this disclosure are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referenced. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this disclosure, "plurality" means at least two, such as two or three, unless otherwise specifically defined.

[0024] In the present invention, unless otherwise specified or limited, the terms "connection" and "fixation" should be understood in a broad sense. For example, "fixation" can mean fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will be able to understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0025] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in this field can implement it. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0026] The present invention provides a method for preparing an all-solid-state battery negative electrode material, comprising the following steps:

[0027] Step S1, weighing a certain amount of red phosphorus and nano-silicon and mixing them by ball milling to obtain a mixture;

[0028] Wherein, the mass ratio of the red phosphorus to the nano-silicon is 5-8:5-2.

[0029] Step S2, mixing the mixture with cyclodextrin by ball milling to obtain a phosphorus-silicon composite material;

[0030] Specifically, the mass proportion of cyclodextrin in the phosphorus silicon composite material is 0.5-5%.

[0031] Step S3: placing the phosphorus-silicon composite material into a polyacyl chloride solution for a period of time, and then treating the polyacyl chloride solution to obtain an all-solid-state battery negative electrode material. The polyacyl chloride solution is obtained by dissolving polyacyl chloride monomers in an organic solvent.

[0032] Specifically, the polyacyl chloride monomer is a difunctional or higher active acyl chloride monomer such as trimesoyl chloride and terephthaloyl chloride, the organic solvent is any one of n-hexane and cyclohexane, and the concentration of the polyacyl chloride solution is 0.01-0.5 mol / L.

[0033] In steps S1 and S2, the ball milling mixing rate is 200-500 rpm, the ball milling time is 15-60 min, and the ball-to-material ratio is 1:20-40.

[0034] Preferably, in step S3, the phosphorus silicon composite material is placed in a polyacyl chloride solution at a reaction temperature of 20-60° C. and reacted for 30 seconds to 2 minutes, and then dried at low temperature to obtain an all-solid-state battery negative electrode material.

[0035] The present invention is described in detail below through specific examples.

[0036] Example 1

[0037] (1) 90 wt% of red phosphorus (9 g) and 10 wt% of nano-silicon (1 g) were weighed and mixed using a planetary ball mill at a medium speed of 250 rpm for 30 min to obtain a mixture;

[0038] (2) Weighing 0.2 g of cyclodextrin and adding it to the ball milling jar of the planetary ball mill in (1), and performing a secondary ball milling on the mixture and the cyclodextrin under the same parameters to obtain a phosphorus-silicon composite material;

[0039] (3) Dissolve trimesoyl chloride in n-hexane solvent to prepare a 0.15 mol / L polyacyl chloride solution, heat the reaction temperature to 30°C, and then immerse the phosphorus silicon composite material prepared in (2) in the polyacyl chloride solution to react for 1 minute. After low-temperature drying, a negative electrode material for an all-solid-state battery is obtained.

[0040] Example 2

[0041] (1) Weigh 50 wt% of red phosphorus (5 g) and 50 wt% of nano-silicon (5 g) and mix them by medium-speed ball milling in a planetary ball mill at a speed of 250 rpm for 30 min to obtain a mixture;

[0042] (2) Weighing 0.5 g of cyclodextrin and adding it to the ball milling jar of the planetary ball mill in (1), and performing a secondary ball milling on the mixture and the cyclodextrin under the same parameters to obtain a phosphorus-silicon composite material;

[0043] (3) Dissolve trimesoyl chloride in n-hexane solvent to prepare a 0.2 mol / L polyacyl chloride solution, heat the reaction temperature to 30°C, and then immerse the phosphorus silicon composite material prepared in (2) in the polyacyl chloride solution to react for 30 seconds. After low-temperature drying, a negative electrode material for an all-solid-state battery is obtained.

[0044] Example 3

[0045] (1) 10 wt% red phosphorus (1 g) and 90 wt% nano-silicon (9 g) were weighed and mixed using a planetary ball mill at a medium speed of 250 rpm for 30 min to obtain a mixture;

[0046] (2) Weighing 0.5 g of cyclodextrin and adding it to the ball milling jar of the planetary ball mill in (1), and performing a secondary ball milling on the mixture and the cyclodextrin under the same parameters to obtain a phosphorus-silicon composite material;

[0047] (3) Dissolve trimesoyl chloride in n-hexane solvent to prepare a 0.2 mol / L polyacyl chloride solution, heat the reaction temperature to 30°C, and then immerse the phosphorus silicon composite material prepared in (2) in the polyacyl chloride solution to react for 30 seconds. After low-temperature drying, a negative electrode material for an all-solid-state battery is obtained.

[0048] The negative electrode materials prepared in Examples 1 to 3 were applied to all-solid-state lithium batteries and the performance of the all-solid-state lithium batteries was tested. The results are shown in Table 1. Specifically, the all-solid-state lithium battery includes a positive electrode, a negative electrode, and a sulfide electrolyte between the positive electrode and the negative electrode. The positive electrode is lithium nickel cobalt manganese oxide (NCM811), the sulfide electrolyte is Li6PS5Cl, and the negative electrode is prepared from the negative electrode material prepared in Example.

[0049] Table 1 All-solid-state lithium battery performance test results

[0050] First charge capacity (mAhg-1) First charge and discharge efficiency (%) Unmodified silicon anode 185 72 Example 1 215 81 Example 2 202 75 Example 3 208 78

[0051] From Table 1, it can be seen that the battery effects made with the modified silicon negative electrode are better than those of the battery including the unmodified silicon negative electrode.

[0052] The beneficial effects of the present invention are as follows:

[0053] 1. The present invention mixes red phosphorus and nano-silicon and reacts the mixture with cyclodextrin. By utilizing the hollow structure of cyclodextrin, the nano-scale phosphorus-silicon mixture is bound within its molecular cavities, thereby limiting the expansion of the negative electrode.

[0054] 2. The present invention further encapsulates the phosphorus-silicon composite material inside the molecular cavity by reacting the phosphorus-silicon composite material, i.e., cyclodextrin coated with the phosphorus-silicon mixture, with a polyacyl chloride solution, thereby preventing the phosphorus-silicon from diffusing out of the molecular cavity under pressure.

[0055] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and the embodiments. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to specific details.

Claims

1. A method for preparing an all-solid-state battery negative electrode material, characterized in that: The following steps are involved: Step S1, weighing a certain mass of red phosphorus and nano-silicon and mixing them by ball milling to obtain a mixture, wherein the mass ratio of the red phosphorus to the nano-silicon is 5-8:5-2; Step S2, mixing the mixture with cyclodextrin by ball milling to obtain a phosphorus-silicon composite material, wherein the mass proportion of cyclodextrin in the phosphorus-silicon composite material is 0.5-5%; Step S3, placing the phosphorus silicon composite material into a polyacyl chloride solution to react for a period of time, and then treating it to obtain an all-solid-state battery negative electrode material, wherein the polyacyl chloride monomer is dissolved in an organic solvent to obtain a polyacyl chloride solution; the polyacyl chloride monomer is an active acyl chloride monomer with a functionality of two or more, the organic solvent is any one of n-hexane and cyclohexane, and the concentration of the polyacyl chloride solution is 0.01-0.5 mol / L.

2. The method for preparing an all-solid-state battery negative electrode material according to claim 1, characterized in that: In steps S1 and S2, the ball milling mixing rate is 200-500 rpm, the ball milling time is 15-60 min, and the ball-to-material ratio is 1:20-40.

3. The method for preparing an all-solid-state battery negative electrode material according to claim 1, characterized in that: The polyacyl chloride monomer is any one of trimesoyl chloride and terephthaloyl chloride.

4. The method for preparing an all-solid-state battery negative electrode material according to claim 1, characterized in that: In step S3, the phosphorus silicon composite material is placed in a polyacyl chloride solution and reacted for 30 seconds to 2 minutes, and then dried at low temperature to obtain an all-solid-state battery negative electrode material.

5. The method for preparing an all-solid-state battery negative electrode material according to claim 1, characterized in that: In step S3, the phosphorus silicon composite material is placed in the polyacyl chloride solution and the reaction temperature is 20-60°C.