Preparation method of high-silicon slag derived porous negative electrode material

Abstract

The application relates to a preparation method of a high-silicon slag derived porous negative electrode material, which comprises the following steps: ① mixing and reacting high-silicon slag and organic substances; ② filtering after the reaction is completed, and taking the filtrate; ③ evaporating and crystallizing the filtrate; and ④ calcining the crystallization product to prepare a silicon-based negative electrode material. The application takes high-silicon slag as raw material to prepare the negative electrode material, the electrochemical performance of which is excellent, the production cost is greatly reduced, the economic benefits of enterprises are improved, the problems of high-silicon slag stacking and the like are solved, and the high-value utilization of high-silicon slag is realized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of chemistry, and particularly relates to a preparation method of a high-silicon slag derived porous negative electrode material. BACKGROUND

[0002] Phosphorus chemical enterprises will produce a large amount of high-silicon slag, which mainly contains silicon dioxide, followed by calcium oxide, and a small amount of aluminum oxide and iron oxide. The main way to dispose of high-silicon slag is to mix it with cement to prepare a retarder or to prepare hollow bricks and other building materials, which is a low-value utilization. With the increasing emphasis on environmental protection and resource recycling, high-value utilization of high-silicon slag has become an urgent industry pain point to be solved.

[0003] Silicon materials are considered to be the ideal choice for the next generation of lithium ion battery negative electrode materials due to their high capacity and low cost, but their poor conductivity and large volume expansion limit their application. CN117894968B patent uses gelatin as a carbon source to construct a continuous conductive network on the surface of silicon powder through a wet coating and pyrolysis process, and prepares a silicon-carbon material with excellent cycle performance and rate performance, but the solid coating layer prepared by this method is easy to separate and the preparation process is complex, which is high in cost. Based on this, the present application proposes a silicon slag derived porous negative electrode material with excellent electrochemical performance and a simple low-cost process. SUMMARY

[0004] In order to solve the above problems, the present application aims to provide a preparation method of a high-silicon slag derived porous negative electrode material, which can prepare a negative electrode material with excellent electrochemical performance; and realize high-value utilization of silicon slag while meeting the requirements of simple manufacturing process and low cost.

[0005] The technical scheme of the present application is as follows:

[0006] A preparation method of a high-silicon slag derived porous negative electrode material, the method comprising the following steps:

[0007] (1) mixing high-silicon slag and organic matter at a certain liquid-solid ratio into a solution and reacting at a certain temperature:

[0008] (2) reacting for a period of time, and after the reaction is completed, filtering and taking the filtrate;

[0009] (3) evaporating and crystallizing the filtrate;

[0010] (4) calcining the crystallization product to prepare a silicon-based negative electrode material.

[0011] Preferably, the composition of high-silicon slag is: silicon dioxide 68%-69%, silicate 15.5%-16.5%, calcium phosphate 14.5%-15.5%, and potassium fluoride 0.5%-1%.

[0012] Preferably, the high-silicon slag is first subjected to pickling, the pickling solution comprising a mixture of one or more of nitric acid, hydrochloric acid, sulfuric acid, the mass concentration of the pickling solution being 30-50%, and during the pickling process, the liquid-solid ratio is 1:1.

[0013] Preferably, the organic substance is a quaternary ammonium base mixture. The presence of the organic base can obtain a high-purity organosilicon, thereby preparing a negative electrode material with excellent electrochemical performance.

[0014] Further preferably, the quaternary ammonium base mixture is: tetramethylammonium hydroxide: tetraethylammonium hydroxide: tetrabutylammonium hydroxide = 1:1:1.

[0015] Preferably, the molar ratio of the quaternary ammonium base to silicon in step (1) is (1.8-3):1, the reaction temperature is 50-100℃, and the liquid-solid ratio is 5-20, further preferably, the liquid-solid ratio is 8-10.

[0016] Further preferably, the total molar amount of the quaternary ammonium base mixture to the molar amount of silicon in the silicon slag is (2-2.5):1.

[0017] Further preferably, in step (1), the molar ratio of tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrabutylammonium hydroxide in the quaternary ammonium base mixture is (0.1-2):(0.1-2):(0.1-2), preferably, the molar ratio of tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrabutylammonium hydroxide is 1:1:1, and the addition ratio of polyethylene glycol is 0.1%-0.2% of the total mass of the high-silicon slag and the quaternary ammonium base mixture.

[0018] Further preferably, in step (1), the liquid-solid ratio is 8-10, and the reaction temperature is 70-100℃.

[0019] Preferably, the reaction time in step (2) is 1-3h.

[0020] Further optimization, the drying method in step (3) is freeze-drying.

[0021] Preferably, in step (4), the calcination atmosphere is nitrogen, the calcination temperature is 700-1000℃, and the calcination time is 1.5-2h.

[0022] Compared with the prior art, the present application has the following advantages:

[0023] (1) The present application uses silicon slag as raw material, and through alkali dissolution and calcination, a high-purity porous carbon-silicon material is prepared, which is used for the preparation of negative electrode material, and can endow it with excellent electrochemical performance.

[0024] (2) The organic base can be combined with the silicon material through a chemical bond in the process, and the silicon is firmly fixed in the carbon material structure after calcination, so that the prepared negative electrode material has good stability.

[0025] (3) The quaternary ammonium base in the application is prepared by mixing a plurality of substances, which can optimize the pore size distribution in the carbon framework after calcination and improve the electrochemical performance.

[0026] (4) The silicon slag is used as a raw material, and the addition of the organic base precisely purifies the silicon element, and the organic base material generates a porous carbon after calcination, which can improve the electrochemical performance of the material.

[0027] (5) The overall preparation process is simple, realizes high-value utilization of the silicon slag, and realizes high-value utilization of the silicon slag while being environmentally friendly. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to specific embodiments of the application. The embodiments are only a part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0029] To better illustrate the above embodiments, the following examples are listed, and the scope of the application is not limited to the listed examples. The silicon slag used in the examples is produced by Yidu Xingfa Chemical Co., Ltd., and the composition is 68%-69% of silicon dioxide, 15.5%-16.5% of silicate, 14.5%-15.5% of calcium hydroxide phosphate dihydrate, and 0.5%-1% of potassium fluoride.

[0030] The quaternary ammonium base mixture used in the examples is a mixture of tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrabutylammonium hydroxide in a ratio of 1:1:1.

[0031] Example 1

[0032] The high-silicon slag is soaked in a mixed solution of sulfuric acid and nitric acid (1:1) at a liquid-solid ratio of 50% for 5h, filtered and dried, and the silicon slag and the quaternary ammonium base mixture are weighed according to the molar mass ratio of base to silicon of 2:1. The mixture is placed in an aqueous solution under the condition of a liquid-solid ratio of 8:1, the temperature is increased to 70℃, and the reaction is carried out for 2h. After filtration, the filtrate is distilled and dried, and the dried solid is placed in a tube furnace under nitrogen atmosphere and heated at 800℃ for 1.5h. Finally, the calcined solid is taken out.

[0033] Example 2

[0034] The high-silicon slag was soaked in a mixed solution of sulfuric acid and nitric acid (3:1) at a liquid-solid ratio of 50% for 5h, filtered and dried. The silicon slag and quaternary ammonium base mixture were weighed according to a molar mass ratio of base to silicon of 2:1, placed in an aqueous solution under a liquid-solid ratio of 9:1, the temperature was raised to 80°C, and the reaction was carried out for 2.5h. The mixture was filtered, the filtrate was distilled and dried, and the dried solid was placed in a tube furnace under a nitrogen atmosphere and heated at 850°C for 2h. Finally, the calcined solid was removed.

[0035] Example 3

[0036] The high-silicon slag was soaked in a mixed solution of sulfuric acid and nitric acid (3:1) at a liquid-solid ratio of 50% for 5h, filtered and dried. The silicon slag and quaternary ammonium base mixture were weighed according to a molar mass ratio of base to silicon of 2.4:1, placed in an aqueous solution under a liquid-solid ratio of 10:1, the temperature was raised to 90°C, and the reaction was carried out for 3h. The mixture was filtered, the filtrate was distilled and dried, and the dried solid was placed in a tube furnace under a nitrogen atmosphere and heated at 900°C for 2h. Finally, the calcined solid was removed.

[0037] Example 4

[0038] The high-silicon slag was soaked in a mixed solution of hydrochloric acid and nitric acid (3:1) at a liquid-solid ratio of 50% for 6h, filtered and dried. The silicon slag and quaternary ammonium base mixture were weighed according to a molar mass ratio of base to silicon of 2.5:1, placed in an aqueous solution under a liquid-solid ratio of 10:1, the temperature was raised to 100°C, and the reaction was carried out for 3h. The mixture was filtered, the filtrate was distilled and dried, and the dried solid was placed in a tube furnace under a nitrogen atmosphere and heated at 1000°C for 2h. Finally, the calcined solid was removed.

[0039] Example 5

[0040] The high-silicon slag was soaked in a mixed solution of hydrochloric acid and nitric acid (1:1) at a liquid-solid ratio of 50% for 8h, filtered and dried. The silicon slag and quaternary ammonium base mixture were weighed according to a molar mass ratio of base to silicon of 2.5:1, placed in an aqueous solution under a liquid-solid ratio of 10:1, the temperature was raised to 100°C, and the reaction was carried out for 3h. The mixture was filtered, the filtrate was distilled and dried, and the dried solid was placed in a tube furnace under a nitrogen atmosphere and heated at 1100°C for 2h. Finally, the calcined solid was removed.

[0041] Example 6

[0042] The high-silicon slag was soaked in a mixed solution of hydrochloric acid and nitric acid (3:1) at a liquid-solid ratio of 50% for 10h, filtered and dried. The silicon slag and quaternary ammonium base mixture were weighed according to a molar mass ratio of base to silicon of 2.5:1, placed in an aqueous solution under a liquid-solid ratio of 10:1, the temperature was raised to 100°C, and the reaction was carried out for 3h. The mixture was filtered, the filtrate was distilled and dried, and the dried solid was placed in a tube furnace under a nitrogen atmosphere and heated at 1200°C for 2h. Finally, the calcined solid was removed.

[0043] Example 7

[0044] The high-silicon slag is soaked in a mixed solution of hydrochloric acid and nitric acid (3:1) at a liquid-solid ratio of 50% for 10 h, filtered and dried. The silicon slag and sodium hydroxide are weighed according to a molar mass ratio of base to silicon of 2.5:1, and placed in an aqueous solution under the condition of a liquid-solid ratio of 10:1. The temperature is raised to 100°C, and the reaction is carried out for 3 h. Filtration is performed, and the filtrate is distilled and dried. The dried solid is placed in a tube furnace under a nitrogen atmosphere, heated at 1200°C for 2 h, and finally the calcined solid is taken out.

[0045] Comparative Example 1

[0046] The high-silicon slag is soaked in a mixed solution of hydrochloric acid and nitric acid (3:1) at a liquid-solid ratio of 50% for 10 h, filtered and dried. The silicon slag and sodium hydroxide are weighed according to a molar mass ratio of base to silicon of 2.5:1, and placed in an aqueous solution under the condition of a liquid-solid ratio of 10:1. The temperature is raised to 100°C, and the reaction is carried out for 3 h. Filtration is performed, and the filtrate is distilled and dried. The dried solid is placed in a tube furnace under a nitrogen atmosphere, heated at 1200°C for 2 h, and finally the calcined solid is taken out.

[0047] Comparative Example 2

[0048] The high-silicon slag is soaked in a mixed solution of hydrochloric acid and nitric acid (3:1) at a liquid-solid ratio of 50% for 10 h, filtered and dried. The silicon slag and a mixture of quaternary ammonium base are weighed according to a molar mass ratio of base to silicon of 2.5:1, and placed in an aqueous solution under the condition of a liquid-solid ratio of 10:1. The temperature is raised to 100°C, and the reaction is carried out for 3 h. Filtration is performed, and the filtrate is distilled and dried. The dried solid is placed in a tube furnace under an air atmosphere, heated at 1200°C for 2 h, and finally the calcined solid is taken out.

[0049] Comparative Example 3

[0050] The high-silicon slag is soaked in a mixed solution of hydrochloric acid and nitric acid (3:1) at a liquid-solid ratio of 50% for 10 h, filtered and dried. The silicon slag and tetraethylammonium hydroxide are weighed according to a molar mass ratio of base to silicon of 2.5:1, and placed in an aqueous solution under the condition of a liquid-solid ratio of 10:1. The temperature is raised to 100°C, and the reaction is carried out for 3 h. Filtration is performed, and the filtrate is distilled and dried. The dried solid is placed in a tube furnace under a nitrogen atmosphere, heated at 1200°C for 2 h, and finally the calcined solid is taken out.

[0051] Comparative Example 4

[0052] The high-silicon slag is soaked in a mixed solution of hydrochloric acid and nitric acid (3:1) at a liquid-solid ratio of 50% for 10 h, filtered and dried. The silicon slag and tetrabutylammonium hydroxide are weighed according to a molar mass ratio of base to silicon of 2.5:1, and placed in an aqueous solution under the condition of a liquid-solid ratio of 10:1. The temperature is raised to 100°C, and the reaction is carried out for 3 h. Filtration is performed, and the filtrate is distilled and dried. The dried solid is placed in a tube furnace under a nitrogen atmosphere, heated at 1200°C for 2 h, and finally the calcined solid is taken out.

[0053] Comparative Example 5

[0054] The high-silicon slag was soaked with a mixed solution of hydrochloric acid and nitric acid (3:1) at a liquid-solid ratio of 50% for 10h, filtered and dried, and the silicon slag and the quaternary ammonium base mixture were weighed according to a molar mass ratio of base to silicon of 2.5:1, placed in an aqueous solution under conditions of a liquid-solid ratio of 10:1, the temperature was raised to 100°C, and the reaction was carried out for 3h, filtered, the filtrate was distilled and dried, and the dried solid was placed in a tube furnace under a nitrogen atmosphere, heated at 1200°C for 2h, and finally the calcined solid was removed.

[0055] Comparative Example 6

[0056] The high-silicon slag was soaked with a mixed solution of hydrochloric acid and nitric acid (3:1) at a liquid-solid ratio of 50% for 10h, filtered and dried, and the silicon slag and the quaternary ammonium base mixture were weighed according to a molar mass ratio of base to silicon of 2.5:1, placed in an aqueous solution under conditions of a liquid-solid ratio of 10:1, the temperature was raised to 100°C, and the reaction was carried out for 3h, filtered, the filtrate was distilled and dried, and the dried solid was placed in a tube furnace under a nitrogen atmosphere, heated at 1200°C for 2h, and finally the calcined solid was removed.

[0057] The porous silicon-carbon obtained by Examples 1-6 was used as an electrode material, and the results of electrochemical performance tests were as follows:

[0058] Table 1

[0059]

[0060] From the experimental data of Examples 1-7, it can be seen that the addition of polyethylene glycol in Example 7 can improve the reactivity of the silicon slag and increase the reaction rate, and the prepared porous silicon-carbon material has better electrochemical performance. In Comparative Example 1, no quaternary ammonium base was involved in the reaction, and the prepared product had no electrochemical performance; in Comparative Example 2, the material prepared in an oxygen atmosphere had no electrochemical performance; and the electrochemical performance of Comparative Examples 3-5 was excellent without the addition of a quaternary ammonium base mixture.

[0061] The above examples explain the technical solutions of the present application, but the present application is not limited to the above examples, i.e. it does not mean that the present application must rely on the above specific examples to be implemented. Any improvement made by a person skilled in the art on the basis of the present application, or equivalent replacement of the materials selected for the present application, etc., all fall within the scope of protection of the patent.

Claims

1. A method for preparing a high-silicon slag-derived porous anode material, characterized in that: The method includes the following steps: (1) High-silica slag and organic matter are mixed in a solution at a certain liquid-solid ratio and reacted at a certain temperature; the organic matter is a quaternary ammonium base; the quaternary ammonium base is composed of tetramethylammonium hydroxide, tetraethylammonium hydroxide and tetrabutylammonium hydroxide, and polyethylene glycol is also added to the mixture of high-silica slag and quaternary ammonium base, with the addition ratio being 0.1%-0.5% of the total mass of the mixture of high-silica slag and quaternary ammonium base; (2) After reacting for a period of time, filter the solution and collect the filtrate. (3) Evaporate and crystallize the filtrate; (4) Silicon-based anode materials were prepared by calcining the crystallized products.

2. The method for preparing the high-silicon slag-derived porous anode material according to claim 1, characterized in that: High-silica slag composition: 68%-69% silica, 15.5%-16.5% silicate, 14.5%-15.5% basic calcium phosphate dihydrate, and 0.5%-1% potassium fluoride.

3. The method for preparing the high-silicon slag-derived porous anode material according to claim 1, characterized in that: The high-silica slag is first pickled. The pickling solution includes one or more of nitric acid, hydrochloric acid, and sulfuric acid, and the mass concentration of the pickling solution is 30-50%.

4. The method for preparing the high-silicon slag-derived porous anode material according to claim 3, characterized in that: The molar ratio of quaternary ammonium base to silicon in step (1) is (1.8-3):1, the reaction temperature is 50℃-100℃, and the liquid-solid ratio is 5-20.

5. The method for preparing the high-silicon slag-derived porous anode material according to claim 1, characterized in that: The molar ratio of tetramethylammonium hydroxide, tetraethylammonium hydroxide and tetrabutylammonium hydroxide in the quaternary ammonium base mixture in step (1) is (0.1-2):(0.1-2):(0.1-2).

6. The method for preparing the high-silicon slag-derived porous anode material according to claim 1, characterized in that: The reaction time for step (2) is 1-5 hours.

7. The method for preparing the high-silicon slag-derived porous anode material according to claim 1, characterized in that: Step (4) The calcination atmosphere is nitrogen, the calcination temperature is 700℃-1000℃, and the calcination time is 1-3h.

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