Lithium battery positive electrode material and preparation method and application thereof

Abstract

The invention discloses a lithium battery positive electrode material and a preparation method and application thereof. Relates to the field of lithium ion batteries. The positive electrode material comprises a hydrogen bond-containing aromatic polymer, the hydrogen bond-containing aromatic polymer comprises an imide group and a hydrogen bond structure, and the hydrogen bond structure comprises an intramolecular hydrogen bond and an intermolecular hydrogen bond. The positive electrode material comprises the hydrogen bond-containing polymer, the polymer contains an imide group and a hydrogen bond structure and contains both intramolecular hydrogen bonds and polymer interchain hydrogen bonds, and the polymer has better molecular accumulation and chain accumulation effects through the hydrogen bond action, so that the crystallinity and the structural stability of the material are improved; therefore, the cycling stability of the battery is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium ion batteries, in particular to a lithium battery positive electrode material and a preparation method and application thereof. BACKGROUND

[0002] In recent years, with the rapid development of global electric new energy vehicle industry and large-scale application of renewable energy, the demand for energy storage technology is growing. Especially, high energy density, long cycle life, high reliability and stable batteries have become an important demand in the fields of electric vehicles, power storage systems and mobile devices. Among many battery technologies, lithium ion batteries (LIBs) have become the most mainstream battery type due to their significant superior performance, especially higher energy density and excellent cycle performance.

[0003] The advantage of lithium batteries is their high energy density, which makes them relatively light in volume and weight, providing longer use time or endurance for electric vehicles and other applications. In addition, lithium ion batteries can maintain good cycle performance during long-time charging and discharging, and have no significant memory effect, which is crucial for mobile devices and electric vehicles, greatly improving their service life. More importantly, lithium batteries are more environmentally friendly than traditional batteries such as lead-acid batteries, with lower environmental impact, in line with the current global green development trend.

[0004] However, the positive electrode material in lithium batteries is crucial to the performance of the battery. The electrochemical performance and production cost of lithium batteries are largely determined by the composition of their positive electrode materials. Currently, the positive electrode materials in commercial lithium batteries are mainly inorganic metal oxides, such as lithium cobaltate (LiCoO2), lithium manganate (LiMn2O4) and lithium iron phosphate (LiFePO4). Lithium cobaltate is widely used in portable electronic devices, while lithium manganate and lithium iron phosphate have more extensive applications in electric vehicles. Although these inorganic metal oxides have high electrochemical performance, they have some obvious shortcomings: first, metal materials are mostly limited resources, and some metals (such as cobalt) have high cost and supply instability; second, metal oxides are non-renewable resources, which are difficult to meet the future large-scale industrialization demand, and their production process may cause certain pollution to the environment. These factors make the current lithium battery positive electrode material face the challenge of sustainable development.

[0005] In this context, organic electrode materials have gradually attracted widespread attention as a potential alternative. Organic electrode materials have many advantages that traditional inorganic materials do not have, especially in terms of sustainability, environmental friendliness, and cost. Organic materials are mainly composed of elements such as carbon (C), hydrogen (H), and oxygen (O) that are abundant in the Earth's crust. These elements are not only abundant and low-cost, but also have a smaller environmental burden during use. Therefore, organic electrode materials have the potential advantages of low cost and environmental friendliness, which is of great significance for realizing green battery technology and promoting sustainable development of the industry.

[0006] In addition, organic materials have lighter weight and good mechanical properties, and their flexibility makes them more competitive in some specific applications. For example, in wearable devices and flexible electronic products, organic electrode materials can provide better battery performance and durability for these lightweight and flexible devices. At the same time, the structure of organic materials can be flexibly adjusted through molecular design, allowing them to be optimized according to different electrochemical performance requirements. For example, by adjusting the length of the molecular chain, introducing different functional groups, or changing the molecular configuration, the electrical conductivity, stability, and cycle performance of the material can be effectively improved.

[0007] These advantages make organic electrode materials an important direction for the future development of lithium-ion battery anode materials. By developing suitable organic electrode materials, it is expected to make important progress in reducing battery costs, improving battery performance, and increasing battery sustainability. However, despite the great potential of organic electrode materials, current research still faces some challenges, especially in terms of electrochemical performance. The energy density and cycle stability of organic electrode materials still have some gaps compared to traditional inorganic metal oxides, which makes their performance in practical applications difficult to compete with inorganic materials.

[0008] First, the electrochemical performance of organic electrode materials is usually limited by their molecular structure and charge transport ability. Although organic materials can be optimized through molecular design, existing organic materials still have deficiencies in energy density and electrical conductivity. Especially during the battery charging and discharging process, organic materials may undergo structural changes, leading to capacity degradation or shortened cycle life. In addition, the stability and conductivity of organic materials also need to be further improved. In order to solve these problems, researchers are exploring different organic material systems, such as polymers, conjugated molecules, and small-molecule organic compounds, in the hope of finding more advantageous electrode materials.

[0009] Secondly, the synthesis process and stability of the organic electrode material also become the difficulty of the research. Compared with inorganic materials, the synthesis process of the organic electrode material is more complex, and instability may occur in the preparation process. Especially in the process of large-scale production, the stability and consistency of the organic material are the key. In order to meet the needs of industrialization, developing more efficient, economic and environmentally friendly preparation process, improving the quality and consistency of the material is the key to promote the application of organic electrode material.

[0010] Therefore, it is urgent to develop a more stable and better performing organic electrode material. SUMMARY

[0011] The purpose of the present application is to develop a more stable and better performing organic positive electrode material.

[0012] The first aspect of the present application is:

[0013] A positive electrode material is provided.

[0014] The second aspect of the present application is:

[0015] A method for preparing a positive electrode material is provided.

[0016] The third aspect of the present application is:

[0017] Application of the positive electrode material.

[0018] Specifically, the technical solution adopted according to the first aspect of the present application is:

[0019] A positive electrode material, the positive electrode material includes a hydrogen-bond-containing aromatic polymer, the hydrogen-bond-containing polymer contains an imide group and a hydrogen bond structure, the hydrogen bond structure includes intramolecular hydrogen bonds and intermolecular hydrogen bonds.

[0020] According to an embodiment of the present application, one of the technical solutions has at least one of the following advantages or beneficial effects:

[0021] The positive electrode material of the present application includes a hydrogen-bond-containing polymer, the polymer contains an imide group and a hydrogen bond structure, which contains both intramolecular hydrogen bonds and interpolymer chain hydrogen bonds. Through the action of hydrogen bonds, the polymer forms a better molecular and chain packing effect, which can improve the crystallinity and structural stability of the material, and further improve the cycle stability of the battery. When used as a lithium battery positive electrode material, it has similar capacity performance to existing positive electrode materials, but has better cycle stability and rate performance, with a specific capacity of 355 mAh / g, a specific capacity of 210 mAh / g after 40 cycles, a capacity retention rate of 60% at 1C high current, and a working voltage range of 1.5-3.5V. It has good application prospects in the field of lithium battery electrode materials.

[0022] According to an embodiment of the present application, the hydrogen-bonded polymer has the following structural formula:

[0023]

[0024] wherein R1, R2 are independently selected from a benzene ring, thiophene or a fused ring.

[0025] According to an embodiment of the present application, the structural formula of R1 is:

[0026]

[0027] According to an embodiment of the present application, the structural formula of R2 is:

[0028]

[0029] Specifically, the technical solution adopted according to the second aspect of the present application is:

[0030] A method for preparing the positive electrode material, comprising the following steps:

[0031] dissolving an aromatic monomer containing anhydride groups and a compound containing amino groups in a solvent, and then performing a polymerization reaction to obtain the positive electrode material.

[0032] According to an embodiment of the present application, the aromatic monomer containing anhydride groups comprises benzene tetra-carboxylic anhydride.

[0033] According to an embodiment of the present application, the compound containing amino groups comprises at least one of p-phenylenediamine dihydrazide and Reductant Red F3B. The p-phenylenediamine dihydrazide contains a hydrazine group (-NH-NH2) in its structure, which provides an amino group that can undergo a condensation reaction with the anhydride groups of benzene tetra-carboxylic anhydride to form an imide group after the loss of a water molecule, and the hydrogen atom in the amino group can form a hydrogen bond with the carbonyl oxygen. The chemical structure of Reductant Red F3B contains two 1-aminoanthraquinone units, and the free amino groups in the units can react with the anhydride groups of benzene tetra-carboxylic anhydride to form an imide structure, and the carbonyl groups on the anthraquinone ring can act as hydrogen bond acceptors to form intermolecular hydrogen bonds with the hydrogen atoms of the amino groups.

[0034] According to an embodiment of the present application, the solvent comprises at least one of dimethylformamide, N-methylpyrrolidone and acetone.

[0035] According to an embodiment of the present application, the polymerization reaction has a reaction condition comprising: the polymerization atmosphere is an inert atmosphere, and / or the polymerization temperature is 60-120°C.

[0036] Another aspect of the present application also provides a positive electrode material layer comprising the conductive agent, the binder and the positive electrode material as described above. Since this application employs all the technical solutions of the positive electrode material as described above, it has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiments.

[0037] Another aspect of the present application also provides a lithium ion battery comprising the negative electrode, the electrolyte, the separator and the positive electrode material as described above in the embodiment of the first aspect. Since this application employs all the technical solutions of the positive electrode material as described above, it has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiments.

[0038] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0039] The above and / or additional aspects and advantages of the present application will become apparent and be readily appreciated from the following description, including the appended drawings, wherein:

[0040] Figure 1 Flow chart of the method for preparing the positive electrode material in Example 1.

[0041] Figure 2 Infrared spectrum of the positive electrode material prepared in Example 1.

[0042] Figure 3 Flow chart of the method for preparing the positive electrode material in Example 2.

[0043] Figure 4 Infrared spectrum of the positive electrode material prepared in Example 2.

[0044] Figure 5 Flow chart of the method for preparing the lithium ion battery in Example 4.

[0045] Figure 6 Lithium battery charge-discharge curve test chart of the lithium battery prepared in Examples 3-4 and Comparative Examples 1-2.

[0046] Figure 7 Lithium battery cycle charge-discharge test chart of the lithium battery prepared in Examples 3-4 and Comparative Examples 1-2. DETAILED DESCRIPTION

[0047] The words "preferred" and "preferably" in the present application refer to embodiments of the present application that can provide certain benefits under certain circumstances. However, other embodiments can also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude those other embodiments from the scope of the present application.

[0048] When a numerical range is disclosed herein, the range is to be construed as continuous along the entire range, including the minimum and maximum values of the range, and every value between the minimum and maximum values of the range. Further, when a range is provided, it is intended to include every integer within the range, unless otherwise indicated. Moreover, when a range is provided, it is intended to include the start and end values of the range, unless otherwise indicated. Additionally, where "or" is used in the description or claims, it is intended to mean an inclusive "or," and not an exclusive "or," unless otherwise indicated. Also, as used in this specification and the appended claims, the singular forms "a," "an" and "the" include plural referents unless the content clearly dictates otherwise. Further, to the extent that any definition or usage of a term in this specification conflicts with a definition or usage of that term in a document incorporated by reference, the definition or usage in this specification prevails.

[0049] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0050] The reagents, methods and devices used in the present application are conventional reagents, methods and devices in the technical field unless otherwise specified.

[0051] Embodiment 1

[0052] A positive electrode material, the structural formula of the positive electrode material is:

[0053]

[0054] The preparation method of the positive electrode material, the preparation flow is as shown in Figure 1 Specifically, the method comprises the following steps:

[0055] 1 mmol of phenyl tetraformate and 1 mmol of p-phenylenediamine dihydrazine were dissolved in 5 mL of dimethylformamide under an inert atmosphere, and stirred at 80°C for 18 hours. After the reaction was completed, methanol was used for washing, and drying was performed in an oven at 80°C to obtain the positive electrode material, which was named as product NHP1, and the yield was 70%.

[0056] The product NHP1 was subjected to infrared spectrum test, and the test results are as shown in Figure 2 Figure 2 The wavenumber is wave number, and the absorbance is absorbance. It can be known from Figure 2 that the infrared characteristic peak indicates that the imide group and the hydrogen bond characteristic functional group in the NHP1 polymer are successfully synthesized, that is, the positive electrode material containing the imide group and the hydrogen bond structure is successfully prepared.

[0057] Embodiment 2

[0058] A positive electrode material, the structural formula of the positive electrode material is: ​

[0059]

[0060] The preparation method of the above positive electrode material, the preparation flowchart is shown in Figure 3 , and specifically comprises the following steps:

[0061] Under an inert atmosphere, 1 mmol of benzene tetra-carboxylic anhydride and 1 mmol of reduced red F3B (CAS is 12227-47-3) are dissolved in 5 mL of dimethylformamide, and stirred at 80°C for 18 hours. After the reaction is completed, methanol is used for multiple washing, and the product is dried in an oven at 80°C to obtain the above positive electrode material, which is named as product NHP2, and the yield is 70%.

[0062] The product NHP2 is subjected to infrared spectrum test, and the test result is shown in Figure 4 , wherein Wavenumber is wave number, and absorbance is absorbance. Figure 4 From Figure 4 , it can be known that the infrared characteristic peak indicates that the imide group and the hydrogen bond characteristic functional group in the NHP2 polymer are successfully synthesized, that is, the positive electrode material containing the imide group and the hydrogen bond structure is successfully prepared.

[0063] Example 3

[0064] A lithium ion battery comprises the product NHP1 prepared in Example 1, a diaphragm, an electrolyte and a lithium sheet.

[0065] Specifically:

[0066] The preparation method of the above lithium ion battery comprises the following steps:

[0067] S1. NHP1, carbon nanotubes (CNT) and polyvinylidene fluoride (PVDF) are weighed and mixed according to a weight ratio of 3:6:1, and after grinding, a tablet is obtained, which is an NHP1-based electrode tablet, and after drying in a 80°C vacuum oven for 12 hours, it is ready for use;

[0068] S2. In an argon glove box, a positive electrode shell, an NHP1 electrode tablet, a diaphragm (and 60 μL of electrolyte is added on the diaphragm), a lithium sheet, a gasket, a spring and a negative electrode shell are sequentially assembled, and after pressure packaging, the preparation of the lithium battery is completed.

[0069] Example 4

[0070] A lithium ion battery comprises the product NHP2 prepared in Example 2, a diaphragm, an electrolyte and a lithium sheet.

[0071] Specifically:

[0072] The preparation method of the above lithium ion battery, the flowchart is shown in Figure 5 , and specifically comprises the following steps:

[0073] S1 NHP2, carbon nanotube (CNT) and polyvinylidene fluoride (PVDF) were weighed and mixed in a weight ratio of 3:6:1, and after grinding, the NHP2-based electrode sheet was obtained by tabletting, and after drying in a vacuum oven at 80°C for 12 hours, it was ready for use;

[0074] S2 In an argon glove box, the positive electrode shell, NHP2 electrode sheet, separator (and 60 μL of electrolyte was added on the separator), lithium sheet, gasket, spring and negative electrode shell were sequentially assembled, and after pressure packaging, the preparation of the lithium battery was completed.

[0075] Comparative Example 1

[0076] The difference between Comparative Example 1 and Example 4 is that Comparative Example 1 uses commercial NCM811 as the positive electrode material of the lithium battery.

[0077] Specifically:

[0078] A preparation method of a lithium ion battery, comprising the following steps:

[0079] S1 NCM811, superconducting carbon black (SP) and polyvinylidene fluoride (PVDF) were weighed and mixed in a weight ratio of 8:1:1, and after grinding, the NCM811-based electrode sheet was obtained by tabletting, and after drying in a vacuum oven at 80°C for 12 hours, it was ready for use;

[0080] S2 In an argon glove box, the positive electrode shell, NCM811 electrode sheet, separator (and 60 μL of electrolyte was added on the separator), lithium sheet, gasket, spring and negative electrode shell were sequentially assembled, and after pressure packaging, the preparation of the lithium battery was completed.

[0081] Comparative Example 2

[0082] The difference between Comparative Example 2 and Example 4 is that Comparative Example 2 uses 1,1'-iminodi anthraquinone (IDAQ) as the positive electrode material of the lithium battery.

[0083] Specifically:

[0084] A preparation method of a lithium ion battery, comprising the following steps:

[0085] S1 IDAQ, carbon nanotube (CNT) and polyvinylidene fluoride (PVDF) were weighed and mixed in a weight ratio of 3:6:1, and after grinding, the IDAQ-based electrode sheet was obtained by tabletting, and after drying in a vacuum oven at 80°C for 12 hours, it was ready for use;

[0086] S2 In an argon glove box, the positive electrode shell, IDAQ electrode sheet, separator (and 60 μL of electrolyte was added on the separator), lithium sheet, gasket, spring and negative electrode shell were sequentially assembled, and after pressure packaging, the preparation of the lithium battery was completed.

[0087] Performance test:

[0088] The lithium battery charge-discharge curves of the lithium batteries prepared in Examples 3-4 and Comparative Examples 1-2 were tested, and the voltage-specific capacity curves of the batteries were obtained as shown in Figure 6 , wherein specific capacity is specific capacity, and voltage is voltage. Figure 6 , wherein specific capacity is specific capacity, and voltage is voltage. Figure 6 (a) of FIG. 4 is the lithium battery charge-discharge curve of the lithium battery prepared in Example 3-4 and Comparative Example 2, Figure 6 (b) of FIG. 4 is the lithium battery charge-discharge curve of the lithium battery prepared in Comparative Example 1. From Figure 6 It can be seen from (a) of FIG. 4 that the discharge specific capacity of the lithium battery based on NHP2 (Example 4) can reach 355 mAh / g, which is significantly higher than that of the lithium battery based on IDAQ (Comparative Example 2), and the working voltage range of which is 1.5-3.5 V. Figure 6 The discharge specific capacity of the commercial NCM811 lithium battery (Comparative Example 1) in (b) of FIG. 4 can reach 185 mAh / g, and the working voltage range of which is 3.0-4.3 V. In comparison, the lithium battery based on NHP2 (Example 4) has higher capacity.

[0089] The lithium battery cycle charge-discharge tests of the lithium batteries prepared in Examples 3-4 were performed in a Blue Electric battery test system, and the battery cycle efficiency-charge-discharge specific capacity curves were obtained as shown in Figure 7 , wherein cycle number is cycle number, specific capacity is specific capacity, and coulombic efficiency is coulombic efficiency. Figure 7 , wherein cycle number is cycle number, specific capacity is specific capacity, and coulombic efficiency is coulombic efficiency. Figure 7 (a) of FIG. 5 is the lithium battery cycle efficiency-charge-discharge specific capacity curve of the lithium battery prepared in Example 3, Figure 7 (b) of FIG. 5 is the lithium battery cycle efficiency-charge-discharge specific capacity curve of the lithium battery prepared in Example 4, Figure 7 (c) of FIG. 5 is the lithium battery cycle efficiency-charge-discharge specific capacity curve of the lithium battery prepared in Comparative Example 1, Figure 7 (d) of FIG. 5 is the lithium battery cycle efficiency-charge-discharge specific capacity curve of the lithium battery prepared in Comparative Example 2, and from Figure 7 It can be seen that the lithium battery based on NHP2 (Example 4) can still reach a specific capacity of 210 mAh / g after 40 cycles of cycle charge-discharge, and the cycle efficiency is as high as 100%, which is significantly better than the lithium battery based on commercial NCM811 (Comparative Example 1) and the lithium battery based on IDAQ (Comparative Example 2). Therefore, it can be seen that this type of hydrogen-bonding polymer is a kind of lithium battery electrode material with excellent performance.

[0090] The above merely illustrates the embodiments of the present application, and does not limit the patent scope of the present application, and any equivalent transformation or direct or indirect application in the related technical field based on the content of the present application is also included in the patent protection scope of the present application.

Claims

1. A cathode material, characterized in that: The cathode material includes an aromatic polymer containing hydrogen bonds, wherein the hydrogen-bonded polymer contains imide groups and a hydrogen bond structure, wherein the hydrogen bond structure includes intramolecular hydrogen bonds and intermolecular hydrogen bonds.

2. The cathode material according to claim 1, characterized in that: The hydrogen-bonded polymer has the following structural formula: R1 and R2 are independently selected from benzene rings, thiophene, or fused rings.

3. The cathode material according to claim 1, characterized in that: The structural formula of R1 is:

4. The cathode material according to claim 1, characterized in that: The structural formula of R2 is:

5. A method for preparing the cathode material according to any one of claims 1 to 4, characterized in that: Includes the following steps: The positive electrode material is obtained by dissolving an aromatic monomer containing an anhydride group and a compound containing an amino group in a solvent and then performing a polymerization reaction.

6. The method according to claim 5, characterized in that: The aromatic monomers containing anhydride groups include phenyltetracarboxylic anhydride.

7. The method according to claim 5, characterized in that: The amino-containing compound includes at least one of dihydrazine terephthalate and Reduction Red F3B.

8. The method according to claim 5, characterized in that: The solvent includes at least one of dimethylformamide, N-methylpyrrolidone, and acetone.

9. The method according to claim 5, characterized in that: The polymerization reaction is carried out under the following conditions: the polymerization atmosphere is an inert atmosphere, and / or the polymerization temperature is 60-120℃.

10. A lithium-ion battery, characterized in that, It includes a negative electrode, an electrolyte, a separator, and a positive electrode material as described in any one of claims 1-4.

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