Preparation method of super-long cycle-stable organic negative electrode plate of sodium-ion battery

Abstract

The invention relates to a preparation method of an organic negative electrode plate with ultra-long cycle stability for a sodium-ion battery. Comprising the following steps: S1, respectively weighing an organic small molecule material, conductive carbon and a binder according to a certain mass ratio, the mass ratio of the organic small molecule material is 50-95%, the mass ratio of the conductive carbon is 2-30%, and the mass ratio of the binder is 3-20%; S2, adding zirconium oxide beads, and putting the mixture into a small oscillator for full oscillation; s3, aluminum foil is evenly coated with the slurry, then the aluminum foil is placed in a vacuum oven to be dried, and the coating thickness ranges from 15 micrometers to 30 micrometers; and S4, fully wetting the pole piece in the electrolyte, and then assembling the pole piece into the battery. Compared with the prior art, the preparation method has the advantages of simple and feasible operation process, environment friendliness and good cycle performance, and is an excellent sodium ion battery negative electrode material.

Description

Technical Field

[0001] The present invention belongs to the field of sodium ion battery negative electrodes, and more specifically, relates to a method for preparing an organic negative electrode sheet for a sodium ion battery with ultra-long cycle stability. Background Art

[0002] Lithium-ion batteries have revolutionized the field of energy storage devices with their high energy density, excellent cycle stability and reliability, and are widely used in fields such as portable electronics and electric vehicles. However, the continued growth in lithium resource consumption as demand grows rapidly has raised concerns about its resource scarcity. As a rare element, lithium supply may be at risk of insufficient supply in the coming decades as the lithium-ion battery market expands. In addition to lithium, lithium-ion batteries typically contain non-widely used transition metals such as copper, nickel and cobalt, with the shortage of cobalt being particularly severe. In addition, the extraction and processing of transition metals are often harmful to the environment and are usually energy intensive.

[0003] Organic materials do not contain toxic or expensive elements and can be produced from renewable resources. The redox chemistry of organic and organometallic compounds is generally less dependent on the nature of the counterions in the balanced reduction / oxidation process. Due to this versatility, organic compounds can be flexibly applied to different types of battery technologies, such as lithium-ion batteries, sodium-ion batteries, and potassium-ion batteries, thereby accelerating the development of alternative battery technologies.

[0004] Therefore, research on organic materials with cyclic stability can effectively promote the development of negative electrode materials for sodium-ion batteries, thereby alleviating the problems caused by the shortage of lithium resources. Summary of the invention

[0005] The purpose of the present invention is to provide a sodium ion battery organic negative electrode material with stable circulation and a preparation method thereof.

[0006] The first aspect of the present invention provides a study on the electrochemical performance of the organic small molecule (Na2C6O6H2) negative electrode material, comprising the following steps.

[0007] The organic negative electrode material for sodium ion batteries according to the present invention exhibits different electrochemical cycle stability when using a carbonate electrolyte and an ether electrolyte.

[0008] (1) Weigh the organic small molecule material (Na2C6O6H2), conductive carbon and binder in a certain proportion; (2) Add small zirconium oxide beads and place in a small oscillator to fully oscillate for a certain period of time; (3) The slurry is uniformly coated on aluminum foil at a certain thickness, and then placed in a vacuum oven at a certain temperature to dry for a period of time; (4) Select a suitable electrolyte, fully wet the electrode, and assemble the battery; Furthermore, in step (1), the mass ratio of the organic small molecule material, the conductive carbon and the binder is 60%:30%:10% or 70%:20%:10%; Furthermore, the shaking time in step (2) is 30-60 minutes; Furthermore, in step (3), the drying temperature is 60-100 degrees Celsius and the drying time is 10-24 hours; Furthermore, in step (4), the electrolyte is selected from carbonate and ether electrolytes.

[0009] According to the present invention, preferably, the electrode material is Na2C6O6H2, the conductive carbon is carbon black, the binder is polyvinylidene fluoride, the addition amount thereof is 60%:30%:10%, an ether electrolyte is used, and the voltage range is 0.05-1.5 V.

[0010] The present invention has the following advantages: 1. The present invention provides a new type of cyclically stable and environmentally friendly material in the field of organic negative electrode materials for sodium ion batteries.

[0011] 2. The material of the present invention does not contain any transition metal elements, and the original material is cheap and easy to obtain and store.

[0012] 3. The material of the present invention has excellent cycle stability and rate performance.

[0013] 4. The ether electrolyte used in the present invention is much better than the carbonate electrolyte.

[0014] 5. The electrochemical performance of the Na2C6O6H2 sodium ion battery negative electrode material of the present invention is excellent and can be cycled for tens of thousands of cycles, indicating that it has good cycle reversibility and structural stability in ether electrolytes and is a highly competitive commercial negative electrode material. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is the structural formula of the organic small molecule (Na2C6O6H2) of the present invention; Figure 2 These are electron photographs of the organic small molecule (Na2C6O6H2) of the present invention in different electrolytes; Figure 3 The Na2C6O6H2 of the present invention is 50 mA g -1 Constant current charge and discharge curves in different electrolytes under the following conditions; Figure 4 The Na2C6O6H2 of the present invention is 50 mA g -1Cycling performance diagram in different electrolytes under ; Figure 5 The present invention is Na2C6O6H2 in ether electrolyte 2 A g -1 Cycle performance diagram below; Figure 6 This is a rate performance diagram of Na2C6O6H2 in ether electrolyte of the present invention. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0017] The present invention will be further described below by means of specific examples.

[0018] Example 1: Preparation of Na2C6O6H2 electrode material and carbonate electrolyte for sodium ion battery negative electrode.

[0019] In this embodiment, the process of the preparation method is as follows: Preparation of electrodes: Na2C6O6H2 material, conductive carbon black (conductive agent) and polyvinylidene fluoride (binder) were mixed in a mass ratio of 60%:30%:10%, and the resulting mixture was transferred to an oscillating tube. Six 3 mm zirconium dioxide beads were added and shaken for 30 minutes to obtain a uniform slurry. The slurry was evenly coated on aluminum foil using a coating machine (MSK-AFA-I) and placed at 100 o C was dried in a vacuum drying oven for 12 h to completely evaporate the solvent, and then cut into circular electrodes with a diameter of 10 mm using a cutting machine (MSK-T10). The electrodes were weighed and the mass of the active substance was calculated to be ~2 mg.

[0020] Electrochemical performance test: All battery assemblies were completed in a glove box (O2wt%≤0.01, H2O wt%≤0.01). The constant current charge and discharge test and long cycle test of R2032 button cells were achieved by Neware CT4000. The test voltage window was 0.05-1.5 V, and the electrolyte used was a carbonate electrolyte.

[0021] Example 2: Preparation of Na2C6O6H2 material and ether electrolyte for sodium ion battery negative electrode.

[0022] The difference between this embodiment and embodiment 1 is that the electrolyte is replaced with an ether electrolyte, and other parameters remain the same.

[0023] The molecular structures of the Na2C6O6H2 materials of Example 1 and Example 2 are as follows: Figure 1 As shown, each molecular structure possesses two carbonyl functional groups that can serve as active sites to store sodium ions.

[0024] Figure 2 The stability of Na2C6O6H2 in carbonate electrolyte and ether electrolyte. It can be seen that no dissolution occurs in either ether electrolyte or carbonate electrolyte, indicating that the material is very stable.

[0025] Figure 3 Comparison of the first two cycles of charge and discharge curves of Na2C6O6H2 in carbonate electrolyte and ether electrolyte. It can be seen that there is not much difference, and both can achieve 200 mAh g -1 The specific capacity is about .

[0026] Figure 4 The cycling test of Na2C6O6H2 material in carbonate electrolyte and ether electrolyte shows that the material has very poor cycling stability in carbonate electrolyte, but is very stable in ether electrolyte.

[0027] Figure 5 The cyclic test of Na2C6O6H2 material in ether electrolyte was carried out, even at 2 A g -1 Under high current density, the material cycled stably for tens of thousands of times with almost negligible attenuation.

[0028] Figure 6 This is the rate performance of Na2C6O6H2 material in ether electrolyte. It can be seen that the material has very excellent rate performance.

[0029] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing an organic negative electrode sheet for a sodium ion battery with ultra-long cycle stability, comprising the following steps: S1, weighing organic small molecule materials, conductive carbon and binder respectively, wherein the mass proportion of organic small molecule materials is 50%-95%, the mass proportion of conductive carbon is 2%-30%, and the mass proportion of binder is 3%-20%; S2, add zirconium oxide beads and oscillate thoroughly in a small oscillator; S3, coating the slurry evenly on aluminum foil, and then placing it in a vacuum oven to dry, wherein the coating thickness is 15 μm-30 μm; S4, assemble the electrode into a battery after fully moistening it in the electrolyte.

2. The method for preparing an organic negative electrode sheet for a sodium ion battery with ultra-long cycle stability according to claim 1, characterized in that: The organic small molecule material is Na2C6O6H2.

3. The method for preparing an organic negative electrode sheet for a sodium ion battery with ultra-long cycle stability according to claim 1, characterized in that: The electrolyte in step S4 is an ether electrolyte.

4. The method for preparing an organic negative electrode sheet for a sodium ion battery with ultra-long cycle stability according to claim 1, characterized in that: In step S3, the slurry is evenly coated on the aluminum foil at a thickness of 15 μm-30 μm and placed at 100 o C in a vacuum drying oven for 12 h.

5. The method for preparing an organic negative electrode sheet for a sodium ion battery with ultra-long cycle stability according to claim 1, characterized in that: In step S2, there are six 3 mm zirconium dioxide beads, which are fully shaken for 30 minutes.

Images