Preparation method of anti-crosstalk long-life sodium ion battery

Abstract

The invention discloses an anti-crosstalk long-life sodium ion battery, which is used for prolonging the cycle life of the sodium ion battery, inhibiting the gas production problem and improving the safety performance. The blocking agent is prepared by grafting the organic metal framework with the chelating agent, then the blocking agent is coated on the positive plate or the diaphragm, and then the sodium ion battery cell is manufactured. Oxygen atoms and nitrogen atoms on the blocking agent contain a large number of lone pair electrons and can firmly adsorb free transition metal ions on a positive electrode, so that the transition metal ions do not reach the surface of a negative electrode any more, and the performances such as battery life and safety are improved.

Description

Technical Field

[0001] The invention relates to the field of sodium ion batteries, and in particular to a method for preparing an anti-crosstalk long-life sodium ion battery and a sodium ion battery blocking agent. Background Art

[0002] With the rapid development of electric vehicles, smart grids and other fields, the demand for lithium resources is increasing, while the reserves of lithium resources are limited and unevenly distributed, resulting in lithium resource shortages becoming an important factor restricting the development of lithium-ion batteries. Sodium-ion battery resources are relatively abundant. Sodium is one of the elements with relatively abundant reserves on the earth. Its content in the earth's crust is about 2.75%, while the content of lithium is only 0.0065%. The abundant sodium resources provide strong support for the large-scale application of sodium-ion batteries. The cost of lithium-ion batteries is relatively high, especially in large-scale applications, which limits their widespread application in some fields. In contrast, the cost of raw materials for sodium-ion batteries is relatively low, which has certain cost advantages. The cost of key materials such as positive and negative electrode materials and electrolytes of sodium-ion batteries is usually lower than that of corresponding materials of lithium-ion batteries. In terms of production process, the production process of some sodium-ion batteries is similar to that of lithium-ion batteries; in the process of industrialization, existing production equipment and technology can be used to a certain extent, thereby reducing the cost of equipment investment and process improvement. With the continuous development of sodium-ion battery technology and the emergence of scale effects, its cost is expected to be further reduced, making its cost advantage more prominent. As the research on sodium-ion batteries continues to develop, their performance continues to improve, gradually approaching the level of lithium-ion batteries. This provides technical support for the industrial application of sodium-ion batteries. In some fields that do not require high energy density, such as energy storage systems and low-speed electric vehicles, sodium-ion batteries have broad application prospects.

[0003] In recent years, there are some technical difficulties in the technology of sodium-ion batteries: after multiple charge and discharge cycles, a large amount of gas will be generated inside the sodium-ion battery. The reasons for the gas generation are: poor stability of the positive electrode material, mismatch of the electrolyte, sodium metal has stronger chemical activity than lithium metal, and it is easy to precipitate on the hard carbon surface. The gas production of sodium-ion batteries will have a negative impact on the performance and safety of the battery, including the following aspects: 1. Capacity decay: gas production will cause the internal pressure of the battery to increase, thereby causing the capacity of the battery to decay. 2. Safety risks: If too much gas is produced, it may cause the internal pressure of the battery to be too high, thereby increasing the safety risks of battery leakage, explosion, etc. 3. Shortened life: gas production will cause the chemical reaction inside the battery to be unstable, thereby shortening the service life of the battery. Therefore, in order to improve the performance and safety of sodium-ion batteries, measures need to be taken to reduce the occurrence of gas production problems.

[0004] At present, the mainstream transition metal oxides, polyanion compounds and Prussian blue compound materials are still in the process of continuous research and development and industrialization. The three materials have their own advantages and disadvantages in terms of specific capacity, conductivity, cycle and other electrochemical properties. They can usually be modified to maximize their strengths and minimize their weaknesses. Transition metal oxide positive electrode materials have poor stability (Na x MO2 (where 0<x≤1, M is a transition metal element)) is composed of transition metal oxides. The variable valence transition metals involved are mainly vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni) and copper (Cu). Among them, manganese and iron, which are relatively abundant in resources, are the most commonly used. Although layered transition metal oxide sodium ion batteries have a high specific capacity, due to the insertion and extraction of sodium and lithium, the layered transition metals are prone to structural changes or phase transitions, resulting in battery cycle decay. Therefore, improving the stability of positive electrode materials is of great significance. During the use of sodium ion batteries, some of the positive electrode active materials will undergo structural decomposition to form transition metal ions. These ions will precipitate on the surface of the negative electrode to form metal dendrites. Subsequently, sodium ions will precipitate on the surface and around the dendrites to form byproducts that produce gas, causing battery bloating. It will also block the micropores on the hard carbon, causing some negative electrodes to fail and reduce the battery capacity. Dendrites may also cause internal short circuits in the battery. Summary of the invention

[0005] The first object of the present invention is to provide: a method for preparing an anti-crosstalk long-life sodium ion battery, the purpose of which is to improve the cycle life of the sodium ion battery, inhibit gas production problems, and improve safety performance.

[0006] A method for preparing an anti-crosstalk long-life sodium ion battery comprises the following steps:

[0007] Step 1: preparing an inhibitor by grafting a chelating agent onto an organic metal framework;

[0008] Step 2: Mix and stir the barrier agent, binder and diluent to form a slurry;

[0009] Step 3: Apply the slurry on the surface of the separator or the positive electrode to form a capture layer;

[0010] Step 4: The positive electrode sheet or separator containing the capture layer is made into a sodium ion battery through stirring, coating, rolling, slitting, laminating, welding, assembling, baking, liquid injection, chemical formation, sealing and capacity separation.

[0011] In the step 1, the organic metal framework is MOF-808 (1579984-19-2, C 24 H 12 O 32 Zr6), MIL-100AL (1200358-58-2, C 18 H 11 Al3O16 )、UIO-66(1072413-89-8、C 48 H 24 O 32 Zr6) at least one.

[0012] In the step 1, the chelating agent is at least one of cyclohexanediaminetetraacetic acid (CDTA), 1,2-diaminocyclopentane-N,N,N',N'-tetraacetic acid (CPDTA), ethylene glycol diethyl ether diaminetetraacetic acid (EGTA), ethylenediaminetetrapropionic acid (EDTP), hydroxyethylenediaminetriacetic acid (HEDTA), diethylenetriaminepentaacetic acid (DTPA), triethylenetetraaminehexaacetic acid (TTHA), and ethylenediaminetetraacetic acid (EDTA).

[0013] In the step 2, the binder is PVDF, PTFE, CMC, SBR, PAA, PVA, PEG, ST, EPM or PEO.

[0014] The diluent is NMP, DMF, DMSO, THF, ethanol, acetonitrile, solvent oil, cyclohexanone or silane.

[0015] The second object of the present invention is to provide a battery prepared by the above-mentioned method for preparing an anti-crosstalk long-life sodium ion battery.

[0016] The third object of the present invention is to provide: a method for preparing an anti-crosstalk long-life sodium ion battery inhibitor, the purpose of which is to remove the formic acid group to form a porous inhibitor with an organic metal framework and a chelating agent.

[0017] A method for preparing an anti-crosstalk long-life sodium ion battery blocking agent comprises the following steps:

[0018] Step 1: adding an organic metal framework, a chelating agent and water into a reaction kettle, stirring evenly, and heating to obtain a reactant;

[0019] Step 2: Filter the reactant to obtain a precipitate;

[0020] Step 3: Wash the precipitate with water for 2-5 times, then wash it with acetone for 2-5 times, and dry it to obtain the inhibitor.

[0021] In the step 1, the heating temperature is 55-65°C and the heating time is 20-28h;

[0022] In the step 3, the drying is carried out under vacuum conditions at 55-65° C. for 12 hours.

[0023] The fourth object of the present invention is to provide a barrier agent prepared by the above barrier agent preparation method.

[0024] The fifth object of the present invention is to provide the use of the above-mentioned inhibitor in the preparation of sodium ion batteries.

[0025] Beneficial Effects

[0026] The oxygen atoms and nitrogen atoms on the inhibitor of the present invention contain a large number of lone pairs of electrons, which can firmly adsorb the transition metal ions that have been freed from the positive electrode, so that they no longer reach the surface of the negative electrode, thereby improving the battery life and safety performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 : Comparison of the lifespan of MOF-808-EDTA system batteries and blank batteries.

[0028] Figure 2 : Comparison of lifespan between MIL-100AL+CDTA system battery cells and blank battery cells.

[0029] Figure 3 : Comparison of lifespan of UIO-66+EGTA system battery cells and blank battery cells. DETAILED DESCRIPTION

[0030] The invention discloses an anti-crosstalk long-life sodium ion battery. The invention discloses an inhibitor made of an organic metal framework grafted chelating agent. The inhibitor, a binder and a diluent are stirred into a slurry, which is then coated on the surface of a diaphragm or a positive electrode sheet to form a capture layer. Finally, the positive electrode sheet or diaphragm containing the capture layer is made into a sodium ion battery through the processes of stirring, coating, rolling, slitting, laminating, welding, assembling, baking, liquid injection, chemical formation, sealing and capacity division.

[0031] In order to further describe the present invention, specific embodiments of the present invention are given below, but the scope of protection claimed in the present invention is not limited to the embodiments.

[0032] Example 1 Preparation of 1.5Ah soft-pack sodium ion battery cell of MOF-808-EDTA system of the present invention

[0033] Reaction principle: MOF-808+EDTA→MOF-808-EDTA+HCOOH

[0034] Step 1: Preparation of MOF-808-EDTA system inhibitor. Take 0.5g MOF-808 (Zr) and 0.95g EDTA-2Na and add them to a stirred kettle, then add 250mL water to the kettle, stir at 40r / min for 2h, and then heat to 60°C for 24h; filter the obtained product to obtain a white precipitate, wash it with water 3 times to remove unreacted EDTA; immerse the obtained solid sample in fresh acetone to exchange the water in the MOF-808-EDTA pores, and repeat the process 3 times; dry the solid at 60°C under vacuum for 12h to obtain a MOF-808-EDTA system inhibitor.

[0035] Step 2: Prepare slurry: Take 0.4 g MOF-808-EDTA inhibitor, 0.021 g PVDF, and 0.28 g NMP and stir at high speed for 4 hours to prepare slurry.

[0036] Step 3: Coating. Take a 12um×76mm PP base film and install it on the coating machine, pour the slurry into the coating machine trough, adjust the coating machine to coat a layer of 5um thick slurry on the PP diaphragm, and then dry it to form a capture layer.

[0037] Step 4: Prepare the battery cell. The positive electrode active material sodium nickel iron manganese oxide, conductive agent SP, conductive agent CNTS, and binder PVDF are added to the solvent NMP at a ratio of 95:2:1:2 and 65% solid content, mixed and stirred into a slurry, and then coated on the aluminum foil, and then dried, rolled and cut to make the positive electrode sheet. Take hard carbon material, conductive carbon black, PTFE, and carbon fiber in a ratio of 95:2:2:1 and add them to the stirring kettle, and apply them on the surface of the aluminum foil, and manufacture the negative electrode sheet according to the same process. Then fold the above negative electrode sheet, diaphragm, and positive electrode sheet into the core body in turn, and finally manufacture it into a sodium ion battery through welding, assembling aluminum-plastic film shell, baking, injection, shelving, formation, and capacity division processes, and make the diaphragm containing the capture layer into a 1.5Ah soft-pack sodium ion battery cell.

[0038] The battery cells were subjected to a 1.5A charge and discharge cycle life test in a battery testing cabinet, and a parallel comparison test was performed on batteries manufactured using diaphragms that were not coated with inhibitors.

[0039] Example 2: Preparation of 1.5Ah soft-pack sodium ion battery cell of the MIL-100AL-CDTA system of the present invention

[0040] Reaction principle: MIL-100AL+CDTA→CAU-7-CDTA+HCOOH

[0041] Step 1: Prepare the MIL-100AL-CDTA system inhibitor. Take 0.2g MIL-100AL and 0.98g CDTA and add them to a stirring kettle, then add 250mL water to the kettle, stir at 40r / min for 2h with a stirring kettle, and then heat to 60°C for 24h; filter the obtained product to obtain a white precipitate, wash it with water 3 times to remove the unreacted CDTA; immerse the obtained solid sample in fresh acetone to exchange the water in the pores of MIL-100AL-CDTA, and repeat the process 3 times; dry the solid at 60°C under vacuum for 12h to obtain the MIL-100AL-CDTA system inhibitor.

[0042] Step 2: Prepare slurry: Take 0.15g MIL-100AL-CDTA system inhibitor, 7.9mg PVDF, and 0.105g NMP and stir at high speed for 4h to make slurry.

[0043] Step 3 and step 4 are the same as those in Example 1.

[0044] The battery cells were subjected to a 1.5A charge and discharge cycle life test in a battery testing cabinet, and a parallel comparison test was performed on batteries manufactured using diaphragms that were not coated with inhibitors.

[0045] Example 3 Preparation of 1.5Ah soft-pack sodium ion battery cell of the UIO-66-EGTA system of the present invention

[0046] Reaction principle: UIO-66+EGTA→UIO-66-EGTA+HCOOH

[0047] Step 1: Prepare the UIO-66-EGTA system inhibitor. Take 0.5g UIO-66 and 0.95g EGTA and add them to a stirring kettle, then add 250mL water to the kettle and stir at 40r / min for 2h, then heat to 60℃ for 24h; filter the obtained product to obtain a white precipitate, wash it with water 3 times to remove the unreacted EGTA; immerse the obtained solid sample in fresh acetone to exchange the water in the pores of UIO-66-EGTA, and repeat the process 3 times; dry the solid at 60℃ under vacuum for 12h to obtain the UIO-66-EGTA system inhibitor.

[0048] Step 2: Prepare slurry: Take 0.4g UIO-66-EGTA inhibitor, 0.021g PVDF, and 0.28g NMP and stir at high speed for 4h to make slurry.

[0049] Step 3 and step 4 are the same as those in Example 1.

[0050] The battery cells were subjected to a 1.5A charge and discharge cycle life test in a battery testing cabinet, and a parallel comparison test was performed on batteries manufactured using diaphragms that were not coated with inhibitors.

[0051] The capacity retention rate curve of the cyclic charge and discharge test of the sodium ion battery obtained in Examples 1-3 is as follows: Figure 1-3 As shown, it can be seen that in the battery of the present invention, an inhibitor made of MOF material and chelating agent is added to the diaphragm. The oxygen atoms and nitrogen atoms in the molecular structure contain a large number of lone pairs of electrons, which can firmly adsorb free transition metal ions and prevent them from reaching the negative electrode surface, thereby improving the battery life and safety performance.

Claims

1. A method for preparing an anti-crosstalk long-life sodium ion battery, characterized in that: The following steps are involved: Step 1: preparing an inhibitor by grafting a chelating agent onto an organic metal framework; Step 2: Mix and stir the barrier agent, binder and diluent to form a slurry; Step 3: Apply the slurry on the surface of the separator or the positive electrode to form a capture layer; Step 4: Make the positive electrode or separator containing the capture layer into a sodium ion battery.

2. The method for preparing an anti-crosstalk long-life sodium ion battery according to claim 1, characterized in that: In the step 1, the organic metal framework is at least one of MOF-808, MIL-100AL, and UIO-66.

3. The method for preparing an anti-crosstalk long-life sodium ion battery according to claim 1, characterized in that: In the step 1, the chelating agent is at least one of cyclohexanediaminetetraacetic acid, 1,2-diaminocyclopentane-N,N,N',N'-tetraacetic acid, ethylene glycol diethyl ether diaminetetraacetic acid, ethylenediaminetetrapropionic acid, hydroxyethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraaminehexaacetic acid, and ethylenediaminetetraacetic acid.

4. The method for preparing an anti-crosstalk long-life sodium ion battery according to claim 1, characterized in that: In the step 2, the binder is PVDF, PTFE, CMC, SBR, PAA, PVA, PEG, ST, EPM or PEO.

5. The method for preparing an anti-crosstalk long-life sodium ion battery according to claim 1, characterized in that: The diluent is NMP, DMF, DMSO, THF, ethanol, acetonitrile, solvent oil, cyclohexanone or silane.

6. The method for preparing an anti-crosstalk long-life sodium ion battery according to claim 1, characterized in that: In the step 1, the method for preparing the barrier agent comprises the following steps: Step 1: adding an organic metal framework, a chelating agent and water into a reaction kettle, stirring evenly, and heating to obtain a reactant; Step 2: Filter the reactant to obtain a precipitate; Step 3: Wash the precipitate with water and dry it to obtain the inhibitor.

7. The method for preparing the barrier agent according to claim 5, characterized in that: In the step 1, the heating temperature is 55-65° C. and the heating time is 20-28 hours.

8. The method for preparing the barrier agent according to claim 5, characterized in that: In the step 3, the drying is carried out under vacuum conditions at 55-65° C. for 12 hours.

9. An anti-crosstalk long-life sodium ion battery, characterized in that: The sodium ion battery is prepared by the preparation method described in any one of claims 1 to 6.

10. Use of the inhibitor according to claim 7 in the preparation of sodium ion batteries.

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