Composite resin-based hard carbon material, sodium ion battery and preparation method thereof

Abstract

The present invention provides a composite resin-based hard carbon material, a sodium ion battery, and a preparation method thereof. The preparation method of the composite resin-based hard carbon material comprises the following steps: preparing a resin mixture containing a phenol-formaldehyde epoxy resin precursor and an aromatic phenolic resin curing agent, curing the mixture at 80-200°C, pulverizing the cured mixture, and performing a high-temperature treatment under an inert atmosphere. Sodium ion batteries prepared using this composite resin-based hard carbon material as the negative electrode material exhibit excellent initial coulombic efficiency, charge-discharge capacity, and cycle stability.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a composite resin-based hard carbon material, a sodium ion battery and a preparation method thereof. Background Art

[0002] In recent years, hard carbon materials have been widely researched. Some research has been conducted on the use of certain types of resins to prepare hard carbon anode materials. However, when used in sodium-ion batteries, the overall performance of existing resin-based hard carbon materials, such as charge-discharge performance and cycle stability, remains low. Summary of the Invention

[0003] Based on this, it is necessary to provide composite resin-based hard carbon materials, sodium ion batteries and preparation methods thereof, so as to improve the charge and discharge performance and cycle stability of sodium ion batteries.

[0004] The present invention adopts the following technical solutions:

[0005] The present invention provides a preparation method of a composite resin-based hard carbon material, comprising the following steps: using a phenol-formaldehyde epoxy resin as a precursor, uniformly mixing the phenol-formaldehyde epoxy resin with an aromatic phenolic resin curing agent in a mass ratio of (10-1):1 to obtain a resin mixture; heat-curing the resin mixture at 80-200°C to obtain a cured composite; crushing the cured composite to obtain a cured powder; and heating the cured powder to 1000-1800°C under inert atmosphere protection for high-temperature treatment to obtain a composite resin-based hard carbon material.

[0006] In some embodiments, the aromatic phenolic resin is preferably selected from at least one of aralkyl phenolic resin, biphenyl phenolic resin, and bisphenol A phenolic resin.

[0007] In some embodiments, the mass ratio of the phenol formaldehyde epoxy resin to the aromatic phenol formaldehyde resin is preferably (5-1):1.

[0008] In some embodiments, the heat preservation and curing time is 1 to 16 hours.

[0009] In some embodiments, the heating rate of the high temperature treatment is 1-15° C. / min, and the duration of the high temperature treatment is 1-10 h.

[0010] In some embodiments, the temperature of the high temperature treatment is preferably 1400-1800°C.

[0011] A composite resin-based hard carbon material prepared by the method.

[0012] The present invention may also provide a negative electrode plate, which is prepared using a negative electrode slurry containing the composite resin-based hard carbon material. Preferably, the negative electrode plate is prepared using a negative electrode slurry containing a conductive agent, a binder, a solvent, and the composite resin-based hard carbon material.

[0013] The present invention may also provide a sodium ion battery comprising the above-mentioned negative electrode sheet. Preferably, the sodium ion battery further comprises a positive electrode sheet, a separator and a sodium ion electrolyte.

[0014] Compared with the prior art, the core advantages of the present invention are:

[0015] Through extensive research and exploration, the present invention discovered that a composite resin-based hard carbon material prepared by subjecting a resin mixture of a phenol formaldehyde epoxy resin (as a precursor) and an aromatic phenolic resin (as a curing agent) to a curing reaction and high-temperature treatment can, when applied to a sodium-ion battery system, improve overall performance such as the first coulombic efficiency, cycle stability, and charge and discharge capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is the SEM image of the composite resin-based hard carbon material of Example 4. DETAILED DESCRIPTION

[0017] The technical concept of the present invention is to provide a composite resin-based hard carbon material, a sodium ion battery using the composite resin-based hard carbon material, and a preparation method thereof, which can improve the comprehensive performance of the sodium ion battery, such as the charge and discharge performance and cycle stability.

[0018] The present invention is further described in detail below in conjunction with specific embodiments so that those skilled in the art can understand the present invention more clearly. The following embodiments are only used to illustrate the present invention, but are not limited to limiting the scope of the present invention. Based on the specific embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. In the embodiments of the present invention, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art; in the embodiments of the present invention, unless specifically specified, the technical means used are conventional means well known to those skilled in the art.

[0019] It is worth noting that, in the present application, aromatic phenolic resin refers to a type of phenolic resin having a benzene ring structure, and this type of phenolic resin contains at least one benzene ring with a delocalized bond.

[0020] Among them, the structural formula of biphenyl phenolic resin is:

[0021]

[0022] The structural formula of aralkylphenolic resin:

[0023]

[0024] The structural formula of bisphenol A phenolic resin:

[0025]

[0026] The structural formula of aliphatic phenolic resin:

[0027]

[0028] The structural formula of phenol formaldehyde epoxy resin:

[0029]

[0030] Sources and physical and chemical indicators of some key materials used in the experiments:

[0031]

[0032] Example 1

[0033] This embodiment provides a method for preparing a composite resin-based hard carbon material, comprising the following steps:

[0034] S1. Evenly mix phenol formaldehyde epoxy resin and biphenyl phenolic resin in a mass ratio of 3:1 to obtain a resin mixture.

[0035] S2, transferring the resin mixture into an alumina ark, and curing it at 80° C. for 8 h to obtain a cured composite.

[0036] S3, grinding the solidified composite into powder using a vibration mill to obtain solidified powder.

[0037] S4, raising the temperature from room temperature to 1000°C at a rate of 2°C / min, high-temperature treating the solidified powder for 2 hours, and cooling to room temperature to obtain a composite resin-based hard carbon material.

[0038] According to tests, the composite resin-based hard carbon material prepared in this embodiment is a hard carbon material having irregular block-shaped particles in the macroscopic form and nano-microporous structures inside the particles, wherein the average pore diameter of the nano-microporous structure is 0.29 nm.

[0039] Example 2

[0040] This embodiment provides a method for preparing a composite resin-based hard carbon material. The process steps are basically the same as those in Example 1, with the only difference being that the mass ratio in step S1 is 1:1, the insulation curing temperature and duration in step S2 are 200°C and 1h respectively, and the high-temperature treatment temperature in step S4 is 1200°C.

[0041] After testing, the composite resin-based hard carbon material prepared in this embodiment is a hard carbon material with irregular block-shaped particles in the macroscopic form and nano-microporous structures inside the particles, wherein the average pore diameter of the nano-microporous structure is 0.57 nm.

[0042] Example 3

[0043] This embodiment provides a method for preparing a composite resin-based hard carbon material. The process steps are basically the same as those in Example 1, with the only difference being that the mass ratio in step S1 is 5:1, the insulation curing temperature and duration in step S2 are 100°C and 16h respectively, and the high-temperature treatment temperature in step S4 is 1400°C.

[0044] The test results show that the composite resin-based hard carbon material prepared in this embodiment is a hard carbon material with irregular block-shaped particles in the macroscopic form and nano-microporous structures inside the particles, wherein the average pore diameter of the nano-microporous structures is 1.05 nm.

[0045] Example 4

[0046] This embodiment provides a method for preparing a composite resin-based hard carbon material. The process steps are basically the same as those in Example 1, with the only difference being that the mass ratio in step S1 is 2:1, the insulation curing temperature and duration in step S2 are 120°C and 10 hours respectively, and the high-temperature treatment temperature in step S4 is 1600°C.

[0047] After testing, the composite resin-based hard carbon material prepared in this embodiment is a hard carbon material with irregular block-shaped particles in the macroscopic form and nano-microporous structures inside the particles, wherein the average pore diameter of the nano-microporous structure is 1.32 nm.

[0048] Example 5

[0049] This embodiment provides a method for preparing a composite resin-based hard carbon material. The process steps are basically the same as those in Example 1, with the only difference being that the mass ratio in step S1 is 4:1, the heat preservation and curing temperature and duration in step S2 are 160°C and 4h respectively, and the high-temperature treatment temperature in step S4 is 1800°C.

[0050] After testing, the composite resin-based hard carbon material prepared in this embodiment is a hard carbon material with irregular block-shaped particles in the macroscopic form and nano-microporous structures inside the particles, wherein the average pore diameter of the nano-microporous structure is 1.58 nm.

[0051] Example 6

[0052] This embodiment provides a method for preparing a composite resin-based hard carbon material. The process steps are basically the same as those in Example 1, except that:

[0053] In step S1, phenol formaldehyde type epoxy resin and bisphenol A type phenolic resin are uniformly mixed in a mass ratio of 1:1 to obtain a resin mixture.

[0054] In step S2, the resin mixture is transferred to an alumina ark and cured at 120°C for 8 hours to obtain a cured composite.

[0055] In step S4, the temperature is raised from room temperature to 1600° C. at a rate of 2° C. / min, and the solidified powder is kept at high temperature for 6 h.

[0056] Example 7

[0057] This embodiment provides a method for preparing a composite resin-based hard carbon material. The process steps are basically the same as those in Example 1, except that:

[0058] In step S1, phenol formaldehyde type epoxy resin and aralkyl phenolic resin are uniformly mixed in a mass ratio of 1:1 to obtain a resin mixture.

[0059] In step S2, the resin mixture is transferred to an alumina ark and cured at 120°C for 8 hours to obtain a cured composite.

[0060] In step S4, the temperature is raised from room temperature to 1600° C. at a rate of 2° C. / min, and the solidified powder is kept at high temperature for 6 h.

[0061] Comparative Example 1

[0062] This comparative example provides a method for preparing a resin-based hard carbon material. The process steps are basically the same as those in Example 1, except that:

[0063] In step S1, phenol formaldehyde type epoxy resin and aliphatic phenolic resin are uniformly mixed in a mass ratio of 3:1 to obtain a resin mixture.

[0064] In step S2, the resin mixture is transferred to an alumina ark and cured at 120°C for 8 hours to obtain a cured composite.

[0065] In step S4, the temperature is raised from room temperature to 1000° C. at a rate of 2° C. / min, and the solidified powder is kept at high temperature for 6 h.

[0066] Comparative Example 2

[0067] This comparative example provides a method for preparing a resin-based hard carbon material. The process steps are basically the same as those in Example 1, except that the heating and curing step S2 in Example 4 is omitted. The other process steps are basically the same as those in Example 4.

[0068] Comparative Example 3

[0069] This comparative example provides a method for preparing a resin-based hard carbon material, comprising the following steps:

[0070] S1, crushing phenol formaldehyde type epoxy resin to obtain powder solid.

[0071] S2, raising the temperature from room temperature to 1000°C at a rate of 2°C / min, treating the powder solid at high temperature for 2 hours, and cooling to room temperature to obtain a resin-based hard carbon material.

[0072] Comparative Example 4

[0073] This comparative example provides a method for preparing a resin-based hard carbon material, comprising the following steps:

[0074] S1, crushing biphenyl phenolic resin to obtain a powder solid.

[0075] S2, raising the temperature from room temperature to 1000°C at a rate of 2°C / min, treating the powder solid at high temperature for 2 hours, and cooling to room temperature to obtain a resin-based hard carbon material.

[0076] Comparative Example 5

[0077] This comparative example provides a method for preparing a resin-based hard carbon material, comprising the following steps:

[0078] S1, mixing phenol formaldehyde epoxy resin and imidazole in a mass ratio of 100:1, adding 10% by mass of ethanol as a solvent, and stirring uniformly to obtain a mixture.

[0079] S2, transferring the mixture to a heater, and heating at 95° C. for 4 h to cure, thereby obtaining a cured product.

[0080] S3, taking out the solidified product, grinding it into powder, and obtaining a ground product.

[0081] S4, transferring the ground product into a reactor, placing it in an argon atmosphere and heating it to 1000° C. (heating rate of 5° C. / min), and carbonizing it for 1 hour to obtain a carbonized product.

[0082] S5, cooling the carbonized product to room temperature and taking it out to obtain a phenol formaldehyde epoxy resin-based nitrogen-doped hard carbon material.

[0083] Performance testing:

[0084] The hard carbon materials prepared in the above test examples were used as negative electrode materials to prepare batteries for performance testing. The method steps are as follows:

[0085] Preparation of negative electrode sheet: The hard carbon material prepared in the above test example was mixed evenly with carbon black and sodium alginate in a mass ratio of 7:2:1, an appropriate amount of deionized water was added, and the mixture was stirred for 6 hours. The mixed slurry was coated on the copper foil current collector and vacuum dried to make the negative electrode sheet.

[0086] In a glove box with an argon atmosphere, the prepared negative electrode sheet was assembled into a button battery with a glass fiber separator, a metal sodium sheet, and a mixed solution of 1.0 mol NaPF6 dissolved in 1 L of ethylene glycol dimethyl ether as the electrolyte.

[0087] The above button battery is subjected to constant current charge and discharge test:

[0088] The test voltage range is 0-2.0V, and the reversible specific capacity and first coulombic efficiency of the sodium ion batteries prepared using the hard carbon materials of each embodiment and comparative example are obtained; the current density (unit: mA / g) is 50, 100, 200, 500, 1000, 2000 and 5000, and the rate performance of the sodium ion batteries prepared using the hard carbon materials of each embodiment and comparative example is obtained; the current density is 500mA / g, and the charge and discharge cycle is 1000 weeks, and the reversible specific capacity retention rate of the sodium ion batteries prepared using the hard carbon materials of each embodiment and comparative example is obtained.

[0089] The performance test results are shown in the following table:

[0090]

[0091]

[0092] It can be seen from the above table that, compared with the comparative example, the comprehensive performance of the sodium ion batteries prepared using the hard carbon materials of Examples 1 to 7 is better.

[0093] In addition, the inventor team found through extensive research that:

[0094] (1) The hard carbon material of the present invention is prepared by mixing phenol formaldehyde epoxy resin and aromatic phenolic resin curing agent in a mass ratio of (10-1):1, and then heat-curing at 80-200°C for 1-16 hours and high temperature (1000-1800°C) for 1-10 hours. The reversible specific capacity, cycle performance, coulombic efficiency and other performance of the hard carbon negative electrode sodium ion battery are better.

[0095] (2) Under the same heat preservation curing and high temperature treatment process conditions, the performance advantages of the hard carbon negative electrode prepared by using aromatic phenolic resin and biphenyl type phenolic resin are obvious.

[0096] (3) In particular, the sodium ion battery assembled using the hard carbon material prepared in the optimal embodiment 4 has higher reversible specific capacity and coulombic efficiency.

[0097] It is important to note that the above embodiments are intended only to further illustrate and describe the technical solutions of the present invention and are not intended to further limit the technical solutions of the present invention. The methods of the present invention are merely preferred implementations and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. 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 method for preparing a composite resin-based hard carbon material, characterized in that: The steps include: Using phenol formaldehyde type epoxy resin as a precursor, the phenol formaldehyde type epoxy resin and aromatic phenolic resin are uniformly mixed in a mass ratio of (5-1):1 to obtain a resin mixture; Curing the resin mixture at 80-200° C. to obtain a cured composite; crushing the solidified composite to obtain solidified powder; Under the protection of an inert atmosphere, heating the solidified powder to 1000-1800° C. for high-temperature treatment to obtain a composite resin-based hard carbon material; The aromatic phenolic resin is selected from at least one of aralkyl phenolic resin, biphenyl phenolic resin and bisphenol A phenolic resin.

2. The method for preparing a composite resin-based hard carbon material according to claim 1, wherein: The heat preservation and curing time is 1 to 16 hours.

3. The method for preparing a composite resin-based hard carbon material according to claim 1, wherein: The heating rate of the high temperature treatment is 1-15°C / min, and the duration of the high temperature treatment is 1-10 hours.

4. The method for preparing a composite resin-based hard carbon material according to claim 1, wherein: The temperature of the high temperature treatment is 1400-1800°C.

5. A composite resin-based hard carbon material prepared by the method according to any one of claims 1 to 4.

6. A negative electrode plate, characterized in that: The negative electrode slurry is prepared by using a negative electrode slurry containing a composite resin-based hard carbon material prepared by the method according to any one of claims 1 to 4.

7. The negative electrode sheet according to claim 6, characterized in that: The negative electrode slurry is prepared by using a negative electrode slurry containing a conductive agent, a binder, a solvent and a composite resin-based hard carbon material prepared by the method according to any one of claims 1 to 4.

8. A sodium ion battery, characterized in that: Including the negative electrode sheet according to claim 6 or 7.

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