Solution combustion synthesis method of LiMn2O4 and lithium battery

Abstract

The invention relates to the technical field of new energy batteries, in particular to a solution combustion synthesis method of LiMn2O4 and a lithium battery. The synthesis method comprises the following steps: preparing a precursor solution containing lithium salt and manganese salt; mixing the precursor solution with a compound playing a role in fuel and complexation, and adjusting the pH value to be greater than 7; stirring at a first preset temperature until black floccules appear; baking the floccules at a second preset temperature, and calcining at a third preset temperature; wherein the third preset temperature is higher than the second preset temperature, and the second preset temperature is lower than 300 DEG C; the synthesis method is simple and easy to operate, the energy consumption can be effectively reduced, the synthesis time is shortened, and meanwhile, the spinel type lithium manganate material prepared by the synthesis method also has the advantages of high purity and small particle size. The preparation raw materials of the positive electrode of the lithium battery comprise the LiMn2O4 material prepared by the synthesis method provided by the invention, and the lithium battery has good electrical properties.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy batteries, and in particular to a solution combustion synthesis method of LiMn2O4 and a lithium battery. Background Art

[0002] Lithium manganese oxide (LiMn2O4) material with a spinel structure has attracted much attention due to its three-dimensional lithium ion channels and excellent rate performance. It is one of the more promising lithium ion positive electrode materials.

[0003] The related technology provides a high-temperature solid-phase method for preparing spinel lithium manganese oxide materials, which includes: first ball milling the raw materials, pre-burning them at 700°C for 15 hours, cooling and crushing them, then calcining them at 850°C for 20 hours, and then slowly cooling and crushing them to obtain the desired material.

[0004] However, the synthesis method of the spar-type lithium manganate material provided by the related art has high energy consumption and is difficult to control the cost during large-scale production. Summary of the Invention

[0005] The object of the present invention is to provide a solution combustion synthesis method of LiMn2O4 and a lithium battery. The synthesis method is simple and easy to operate, can effectively reduce energy consumption and shorten the synthesis time. At the same time, the crystal-type lithium manganese oxide material prepared by the synthesis method also has the advantages of high purity and small particle size. The raw material for preparing the positive electrode of the lithium battery of the present invention includes the LiMn2O4 material prepared by the synthesis method of the present invention, and the lithium battery has good electrical properties.

[0006] The present invention is achieved in that: In a first aspect, the present invention provides a solution combustion synthesis method of LiMn2O4, comprising: preparing a precursor solution containing a lithium salt and a manganese salt; The precursor solution is mixed with a compound serving as a fuel and a complexing agent, and the pH is adjusted to be greater than 7; stirring at a first preset temperature until black flocs appear; The flocculent material is baked at a second preset temperature and then calcined at a third preset temperature; wherein the third preset temperature is greater than the second preset temperature, and the second preset temperature is less than 300°C.

[0007] In an optional embodiment, the molar ratio of the metal ions in the precursor solution to the compound acting as fuel and complexing agent is 1:1 to 1:1.5.

[0008] In an optional embodiment, the second preset temperature is 260±10°C.

[0009] In an optional embodiment, the baking time is 5±2 hours.

[0010] In an optional embodiment, the third preset temperature is 800±100°C.

[0011] In an optional embodiment, the calcination time is 6 to 11 hours.

[0012] In an optional embodiment, the first preset temperature is 100±5° C.; and the stirring speed is 200±10 r / min.

[0013] In an optional embodiment, in the step of adjusting the pH, the adjusting agent includes aqueous ammonia; wherein, after the precursor is mixed with the compound that acts as a fuel and a complexing agent, the pH is adjusted to 8-9.

[0014] In an optional embodiment, the molar ratio of lithium ions of the lithium salt to manganese ions of the manganese salt is 1:1.8 to 1:2.2.

[0015] In an optional embodiment, the lithium salt includes at least one of lithium nitrate and lithium acetate, the manganese salt includes at least one of manganese nitrate and manganese acetate; and the compound acting as a fuel and a chelating agent includes at least one of glycine or urea.

[0016] In a second aspect, the present invention provides a lithium battery, wherein the raw material for preparing the positive electrode of the lithium battery includes the LiMn2O4 material prepared by any of the aforementioned LiMn2O4 solution combustion synthesis methods.

[0017] The solution combustion synthesis method of LiMn2O4 of the present invention has the following beneficial effects: In the solution combustion synthesis method of LiMn2O4 provided by an embodiment of the present invention, the temperature of at least part of the process heating is less than 300°C, that is, the temperature when the flocs are baked is less than 300°C. Therefore, the process of synthesizing LiMn2O4 can be reduced, which is beneficial to effectively control costs when producing LiMn2O4.

[0018] Moreover, the LiMn2O4 prepared by the solution combustion synthesis method of LiMn2O4 provided in the embodiment of the present invention also has the advantages of high purity and small particle size.

[0019] The beneficial effects of the lithium battery of the present invention include: the raw material for preparing the positive electrode of the lithium battery provided by the embodiment of the present invention includes the LiMn2O4 material prepared by the above-mentioned solution combustion synthesis method of LiMn2O4; the lithium battery has good electrical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 is the XRD pattern of LiMn2O4 prepared in Example 1 of the present invention; Figure 2 This is the mapping diagram of LMn2O4 prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0022] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.

[0023] Lithium manganese oxide (LiMn2O4) material with spinel structure is one of the most promising lithium-ion positive electrode materials.

[0024] The preparation method provided by the related technology is a high-temperature solid-phase method, which includes: first ball milling the raw materials, pre-burning at 700°C for 15 hours, cooling and crushing, then calcining at 850°C for 20 hours, and then slowly cooling and crushing to obtain the required material.

[0025] However, the high-temperature solid-phase method has high energy consumption and a long time, making it difficult to control costs in large-scale production.

[0026] In order to improve the above problems, the present disclosure provides a solution combustion synthesis method of LiMn2O4; the synthesis method is simple and easy to operate, can effectively reduce energy consumption and shorten the synthesis time, and the crystal-type lithium manganese oxide material prepared by the synthesis method also has the advantages of high purity and small particle size.

[0027] The solution combustion synthesis method of LiMn2O4 disclosed in the present invention comprises: preparing a precursor solution containing a lithium salt and a manganese salt; The precursor solution is mixed with a compound serving as a fuel and a complexing agent, and the pH is adjusted to be greater than 7; stirring at a first preset temperature until black flocs appear; The flocculent material is baked at a second preset temperature and then calcined at a third preset temperature; wherein the third preset temperature is greater than the second preset temperature, and the second preset temperature is less than 300°C.

[0028] In the solution combustion synthesis method of LiMn2O4 disclosed in the present invention, the temperature of at least part of the process heating is less than 300°C, that is, the temperature when the flocs are baked is less than 300°C. Therefore, the process of synthesizing LiMn2O4 can be reduced, which is beneficial for effectively controlling costs when producing LiMn2O4.

[0029] Moreover, the LiMn2O4 prepared by the solution combustion synthesis method of LiMn2O4 provided in the embodiment of the present invention also has the advantages of high purity and small particle size.

[0030] Optionally, the molar ratio of lithium ions of the lithium salt to manganese ions of the manganese salt is 1:1.8 to 1:2.2, for example, 1:1.8, 1:1.9, 1:2, 1:2.1, 1:2.2, etc., which is not specifically limited here.

[0031] Optionally, the lithium salt includes at least one of lithium nitrate and lithium acetate, and the manganese salt includes at least one of manganese nitrate and manganese acetate.

[0032] Alternatively, in some embodiments, preparing the precursor solution comprises mixing lithium nitrate and manganese nitrate tetrahydrate having a molar ratio of lithium ions to manganese ions of 1:2 with excess ultrapure water.

[0033] Of course, in other embodiments, the precursor solution can also be prepared by mixing lithium acetate, manganese nitrate, and ultrapure water, or mixing lithium acetate, manganese acetate, and ultrapure water, or mixing lithium nitrate, manganese acetate, and ultrapure water, or mixing lithium nitrate, lithium acetate, manganese nitrate, and ultrapure water, or mixing lithium nitrate, manganese acetate, manganese nitrate, and ultrapure water, etc., and is not specifically limited here.

[0034] Optionally, at least one of glycine and urea may serve as both a fuel and a complexing agent.

[0035] Optionally, the molar ratio of the metal ions in the precursor solution to the compound serving as the fuel and the complexing agent is 1:1 to 1:1.5, for example, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, etc., which is not specifically limited here.

[0036] Taking glycine as an example, glycine, as a fuel and chelating agent, has a high calorific value of combustion. The gas released by combustion can prevent the precursor particles from agglomerating and form a loose and porous substance. Secondly, glycine can form a uniform complex with metal ions and burn to form uniform particles.

[0037] Furthermore, if the molar ratio of glycine added as a fuel to a complexing agent is less than 1, the fuel is insufficient, and unreacted metal salts are likely to remain, leading to particle aggregation. If the molar ratio of glycine is equal to 1, the reaction is complete, resulting in a highly pure synthesized material with a uniform particle size distribution. If the molar ratio of glycine is greater than 1, the glycine is in excess, generating reducing gas at high temperatures, inhibiting particle growth and producing a product with a smaller particle size. Therefore, optimizing the ratio of fuel to complexing agent not only ensures reliable bonding of lithium ions, manganese ions, and the complexing agent, but also facilitates the formation of high-purity, small-particle LiMn2O4 materials.

[0038] Optionally, the first preset temperature is 100±5°C, for example: 95°C, 97°C, 100°C, 102°C, 105°C, etc., which are not specifically limited here; the stirring speed is 200±10r / min, for example: 190r / min, 195r / min, 200r / min, 205r / min, 210r / min, etc., which are not specifically limited here. If the stirring speed is too low, the metal salt, fuel and complexing agent are not mixed evenly, resulting in incomplete combustion reaction; if the stirring speed is too high, bubbles will be generated, affecting the porosity of the product; if the stirring temperature is low, the dissolution is insufficient and a mixed phase is generated; if the stirring temperature is too high, part of the precursor will agglomerate, and the gel will burn prematurely. Therefore, optimizing the stirring temperature and speed is beneficial to improving the synthesis efficiency of the lithium manganese oxide material and ensuring the reliability of the combination of metal ions and complexing agents.

[0039] Optionally, in the step of adjusting the pH, the regulator includes aqueous ammonia; wherein, after the precursor is mixed with the compound serving as the fuel and the complexing agent, the pH is adjusted to 8-9, for example: 8, 8.2, 8.5, 8.8, 9, etc., which is not specifically limited here.

[0040] It should be noted that the mass concentration or volume concentration of the ammonia water is not limited, as long as the pH can be adjusted to 8-9 in the end.

[0041] Optionally, the second preset temperature is 260±10°C, for example, 250°C, 255°C, 260°C, 265°C, 270°C, etc., which is not specifically limited here.

[0042] Optionally, the baking time is 5±2 hours, for example, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, etc., which is not specifically limited here.

[0043] It should be noted that the black flocculent precursor is generated by heating and stirring, and can be directly baked.

[0044] Since the black floc precursor contains a certain amount of water, baking is used to remove this residual water and prevent the precursor from splashing during high-temperature calcination. Secondly, it allows the complexing agent (e.g., glycine) and the metal ions to fully complex and remove unreacted substances, thereby improving the purity of the synthesized product. Therefore, baking at a lower temperature can achieve complexation between the metal ions and the complexing agent while ensuring high complexation efficiency.

[0045] Controlling a lower baking temperature and a shorter baking time can effectively save energy consumption, help control the cost of lithium manganese oxide material synthesis, and improve environmental protection.

[0046] Optionally, the third preset temperature is 800±100°C, for example, 700°C, 750°C, 800°C, 850°C, 900°C, etc., which is not specifically limited here.

[0047] Optionally, the calcination time is 6 to 11 hours, for example, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, etc., which is not specifically limited here.

[0048] During synthesis, if the calcination temperature is too low, the reaction will be incomplete and impurities will be easily generated. If the calcination temperature is too high, the precursor particles will sinter, forming dense blocks, and the product will also be easily decomposed. Therefore, calcining at a higher temperature can not only promote grain growth and ensure the material has a high purity phase, but also avoid material sintering, shorten the calcination preparation time, save energy, and achieve the goals of reducing costs, protecting the environment, and improving production efficiency.

[0049] The present disclosure also provides a lithium battery, the raw material for preparing the positive electrode of which includes LiMn2O4 material prepared by the solution combustion synthesis method of LiMn2O4 disclosed in the present disclosure; the lithium battery has good electrical properties.

[0050] It should be noted that the specific preparation method of the lithium battery disclosed in the present invention is similar to the related art and will not be repeated here.

[0051] The present invention is described in further detail below with reference to the examples.

[0052] Example 1 Step 1: Lithium nitrate and manganese nitrate tetrahydrate are weighed according to a molar ratio of lithium ion to manganese ion of 1:2, and fully dissolved in an excess of ultrapure water to prepare a precursor solution.

[0053] Step 2: Glycine was added to the precursor solution prepared in step 1 and fully dissolved according to the molar ratio of total metal ions to glycine in the precursor solution of 1:1.2. Ammonia water was added to adjust the pH of the solution to 8.0.

[0054] Step 3: Place the mixed solution in step 2 on a magnetic heating stirring table, and set the conditions to 100° C. and a rotation speed of 200 r / min.

[0055] Step 4: Heat and stir until gray-black flocculent powder appears in the beaker.

[0056] Step 5: Place the gray-black flocculent powder obtained in step 4 in a forced air drying oven and bake it at 260° C. for 5 hours to obtain a precursor.

[0057] Step 6: calcine the precursor in step 5 at 800° C. in a muffle furnace for 10 hours, and grind it to obtain spinel lithium manganate (LiMn2O4) material.

[0058] Example 2 Step 1: Lithium nitrate and manganese nitrate tetrahydrate were weighed according to a molar ratio of lithium ion to manganese ion of 1:1.8, and fully dissolved in an excess of ultrapure water to prepare a precursor solution.

[0059] Step 2: Glycine was added to the precursor solution prepared in step 1 and fully dissolved according to the molar ratio of total metal ions to glycine in the precursor solution of 1:1. Ammonia water was added to adjust the pH of the solution to 9.0.

[0060] Step 3: Place the mixed solution in step 2 on a magnetic heating stirring table, and set the conditions to 95° C. and a rotation speed of 190 r / min.

[0061] Step 4: Heat and stir until gray-black flocculent powder appears in the beaker.

[0062] Step 5: Place the gray-black flocculent powder obtained in step 4 in a forced air drying oven and bake it at 250° C. for 6 hours to obtain a precursor.

[0063] Step 6: calcine the precursor in step 5 at 700° C. in a muffle furnace for 11 hours, and grind it to obtain spinel lithium manganate (LiMn2O4) material.

[0064] Example 3 Step 1: Lithium nitrate and manganese nitrate tetrahydrate were weighed according to a molar ratio of lithium ion to manganese ion of 1:2.2, and fully dissolved in an excess of ultrapure water to prepare a precursor solution.

[0065] Step 2: Glycine was added to the precursor solution prepared in step 1 and fully dissolved according to the molar ratio of total metal ions to glycine in the precursor solution of 1:1.5. Ammonia water was added to adjust the pH of the solution to 8.5.

[0066] Step 3: Place the mixed solution in step 2 on a magnetic heating stirring table, and set the conditions to 105° C. and a rotation speed of 210 r / min.

[0067] Step 4: Heat and stir until gray-black flocculent powder appears in the beaker.

[0068] Step 5: Place the gray-black flocculent powder in step 4 in a forced air drying oven and bake it at 270° C. for 4 hours to obtain a precursor.

[0069] Step 6: calcine the precursor in step 5 at 900° C. in a muffle furnace for 9 hours, and grind it to obtain spinel lithium manganate (LiMn2O4) material.

[0070] Example 4 The difference between Example 4 and Example 1 is that the lithium salt in Example 4 is lithium acetate, the manganese salt is manganese acetate, and other process parameters refer to Example 1.

[0071] Example 5 The difference between Example 5 and Example 1 is that Example 5 uses urea instead of glycine, and other process parameters refer to Example 1.

[0072] Comparative Example 1 Lithium carbonate and manganese manganese oxide are ball-milled, pre-fired at 700°C for 15 hours, cooled and crushed, and then calcined at 850°C for 20 hours. After slowly cooling, they are crushed to obtain spinel lithium manganate (LiMn2O4) material.

[0073] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the flocs formed in step 4 are not baked, but are directly calcined in step 6; other process parameters refer to Example 1.

[0074] The spinel lithium manganate (LiMn2O4) materials of Example 1, Comparative Example 1 and Comparative Example 2 were subjected to XDR test. The test results are shown in Figure 1 .

[0075] according to Figure 1 As can be seen, the XRD pattern of the LiMn2O4 in Example 1 exhibits distinct characteristic peaks. Furthermore, the characteristic peak intensity of Example 1 is significantly higher than that of Comparative Examples 1 and 2, indicating a complete and well-ordered crystal structure. Comparison with a standard LiMn2O4 card demonstrates high synthesis purity with no impurity peaks.

[0076] Referring to GB / T 23414-2021, the spinel lithium manganese oxide (LiMn2O4) material of Example 1 was subjected to mapping characterization. The results are shown in Figure 2 .

[0077] according to Figure 2 It can be seen that the distribution of various elements in the spinel lithium manganate (LiMn2O4) material of Example 1 is relatively uniform.

[0078] With reference to GB / T 19077-2016, the particle sizes of the lithium manganate (LiMn2O4) materials of Example 1 and Comparative Examples 1 and 2 were tested. The results are shown in Table 1.

[0079] Table 1. Particle size distribution

[0080] The results of the Malvern laser particle size analyzer test showed that the particle size of Example 1 was significantly smaller than that of Comparative Examples 1 and 2, indicating that the lithium manganate material synthesized by the solution combustion method has the characteristic of small particle size.

[0081] In summary, the solution combustion synthesis method of LiMn2O4 of the present invention is simple and easy to operate, can effectively reduce energy consumption and shorten the synthesis time. At the same time, the spinel-type lithium manganate material prepared by this synthesis method also has the advantages of high purity and small particle size.

[0082] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A solution combustion synthesis method of LiMn2O4, characterized in that: include: preparing a precursor solution containing a lithium salt and a manganese salt; The precursor solution is mixed with a compound that acts as a fuel and a complexing agent, and the pH is adjusted to be greater than 7; stirring at a first preset temperature until black flocs appear; The flocculent material is baked at a second preset temperature and then calcined at a third preset temperature; wherein the third preset temperature is greater than the second preset temperature, and the second preset temperature is less than 300°C.

2. The solution combustion synthesis method of LiMn2O4 according to claim 1, characterized in that: The molar ratio of the metal ions in the precursor solution to the compound acting as fuel and complexing agent is 1:1 to 1:1.

5.

3. The solution combustion synthesis method of LiMn2O4 according to claim 1, characterized in that: The second preset temperature is 260±10°C.

4. The solution combustion synthesis method of LiMn2O4 according to claim 3, characterized in that: The baking time is 5±2h.

5. The solution combustion synthesis method of LiMn2O4 according to claim 1, characterized in that: The third preset temperature is 800±100°C.

6. The solution combustion synthesis method of LiMn2O4 according to claim 5, characterized in that: The calcination time is 6 to 11 hours.

7. The solution combustion synthesis method of LiMn2O4 according to claim 1, characterized in that: The first preset temperature is 100±5° C.; the stirring speed is 200±10 r / min.

8. The solution combustion synthesis method of LiMn2O4 according to claim 1, characterized in that: In the step of adjusting the pH, the adjusting agent includes aqueous ammonia; wherein, after the precursor is mixed with the compound that acts as a fuel and a complexing agent, the pH is adjusted to 8-9.

9. The solution combustion synthesis method of LiMn2O4 according to claim 1, characterized in that: The molar ratio of lithium ions of the lithium salt to manganese ions of the manganese salt is 1:1.8 to 1:2.2; and / or, The lithium salt includes at least one of lithium nitrate and lithium acetate, the manganese salt includes at least one of manganese nitrate and manganese acetate; and the compound that acts as a fuel and a complexing agent includes at least one of glycine and urea.

10. A lithium battery, characterized in that: The raw material for preparing the positive electrode of the lithium battery includes the LiMn2O4 material prepared by the solution combustion synthesis method of LiMn2O4 as described in any one of claims 1-9.

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