Sodium supplementing material for sodium ion hybrid capacitor and preparation method of sodium supplementing material

Abstract

The invention belongs to the technical field of hybrid capacitors, and particularly relates to a sodium supplementing material for a sodium ion hybrid capacitor and a preparation method of the sodium supplementing material. The preparation method comprises the following steps: adding absolute ethyl alcohol into an aqueous solution of sodium oxalate, fully mixing, adding Super P, and carrying out spray drying on a solution in which the Super P is fully dispersed to obtain the sodium supplementing material for the sodium ion hybrid capacitor. Through an innovative preparation process, the size structure of sodium oxalate particles is successfully reduced, and the sodium oxalate particles are uniformly compounded with the Super P carbon material, so that the conductivity of the sodium oxalate is greatly improved, the decomposition voltage of the sodium oxalate is reduced, and meanwhile, the utilization rate is improved. When the composite material is applied to a sodium ion hybrid capacitor, consumption of sodium ions in an electrolyte in the SEI film forming process can be effectively supplemented, and the electrochemical performance of the capacitor is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of hybrid capacitors, and in particular relates to a sodium-supplementing material for sodium-ion hybrid capacitors and a preparation method thereof. Background Art

[0002] Sodium-ion hybrid capacitors are a new type of electrochemical energy storage device that combines the high energy density of sodium-ion batteries and the high power density characteristics of supercapacitors. Its positive electrode usually uses a capacitive material (such as activated carbon), and the negative electrode uses a battery-type material (such as hard carbon). Sodium-ion hybrid capacitors achieve energy storage through the adsorption / desorption and reversible insertion / deinsertion of sodium ions between the positive and negative electrodes. They have the advantages of low cost, abundant resources, and environmental friendliness, and show broad application prospects in large-scale energy storage, electric vehicles, and portable electronic devices. However, during the first charge and discharge process of sodium-ion hybrid capacitors, the negative electrode material (such as hard carbon) will consume some sodium ions due to the formation of a solid electrolyte interface film, resulting in irreversible capacity loss, reducing the energy efficiency and cycle life of the device. Pre-sodiumization technology has become the key to solving this problem. Pre-sodiumization can effectively compensate for the sodium ion loss during the first charge and discharge process by introducing additional sodium ions into the hybrid capacitor, thereby improving the overall electrochemical performance of the device.

[0003] At present, pre-sodiumization methods include electrochemical pre-sodiumization, addition of sodium supplementation reagents and direct contact methods. Among them, although electrochemical pre-sodiumization can accurately control the amount of sodium ions introduced, its process is complicated and requires additional power supply equipment, which is not conducive to large-scale production. The direct contact method is to directly contact metallic sodium with the negative electrode material to achieve sodiumization, but metallic sodium is extremely active and extremely sensitive to humidity and temperature. Therefore, it requires a harsh operating environment (such as anhydrous and oxygen-free conditions), and it is difficult to uniformly control the degree of sodiumization, which limits its practical application. In contrast, sodium supplementation by adding sodium supplementation reagents has the advantages of simple operation, low cost, and easy large-scale production, and has received widespread attention.

[0004] As a common sodium source, sodium oxalate has the characteristics of low cost and moderate decomposition voltage. In principle, it is an ideal chemical pre-sodiumization reagent. Through the decomposition reaction of sodium oxalate, sodium ions can be efficiently introduced into the electrolyte, significantly improving the electrochemical performance of sodium ion hybrid capacitors. In addition, the sodium oxalate pre-sodiumization process has low environmental requirements and is highly safe and environmentally friendly. However, sodium oxalate crystals have large particle size and poor conductivity, which not only leads to a significant increase in the actual decomposition voltage during the electrolysis process, but also results in a low utilization rate of active substances. Therefore, solving the problems caused by the large particle size of sodium oxalate crystals has important research value and application potential for the application of sodium oxalate in the pre-sodiumization technology of sodium ion hybrid capacitors. Summary of the Invention

[0005] The purpose of the present invention is to provide a sodium-supplementing material for sodium ion hybrid capacitors and a preparation method thereof, which can solve the problem caused by the large particle size of sodium oxalate crystals and is conducive to the application of sodium oxalate in the pre-sodiumization technology of sodium ion hybrid capacitors.

[0006] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0007] A sodium-supplementing material for sodium-ion hybrid capacitors is obtained by the following preparation method: first, sodium oxalate is dissolved in deionized water, then anhydrous ethanol is added, SuperP is added after thorough mixing, and the solution after SuperP is fully dispersed is spray-dried to obtain the sodium-supplementing material for sodium-ion hybrid capacitors.

[0008] The mass ratio of sodium oxalate to SuperP is 1-20:1. The volume ratio of deionized water to anhydrous ethanol is 20-200:1.

[0009] The sodium oxalate has a columnar structure, with some parts having a length of more than 10 microns. There is no particular requirement for the concentration of sodium oxalate in the aqueous solution of sodium oxalate.

[0010] When SuperP is fully dispersed, stirring and ultrasonication are performed respectively, and the stirring and ultrasonication time are respectively not less than 1 hour.

[0011] The spray drying is carried out using a spray dryer with a feed rate of 10-30 ml / min, an air inlet temperature of 200° C.-250° C., and an exhaust air temperature of 80° C.-150° C.

[0012] Specifically, the preparation method of the present invention comprises the following steps:

[0013] Step 1): weigh raw sodium oxalate (Aladdin, purity ≥99%) and dissolve it in deionized water to form solution A;

[0014] Step 2): Add anhydrous ethanol to solution A and stir;

[0015] Step 3): SuperP is added to the solution treated in step 2) to form solution B;

[0016] Step 4): Stirring and ultrasonicating solution B to allow SuperP to be evenly dispersed in the solution;

[0017] Step 5): Solution B is spray-dried and finally collected to obtain a sodium-replenishing material that can be used in sodium-ion hybrid capacitors.

[0018] The present invention mainly considers the use of low-priced sodium oxalate that can be directly purchased on the market. When applied on a large scale, the cost advantage will be very obvious. The sodium oxalate purchased directly has the problem of excessively large particle size, such as some particle sizes are greater than 10 microns, and there is a certain agglomeration phenomenon between the particles. The present invention selects SuperP with a small particle size to mix with sodium oxalate. The addition of SuperP greatly improves the conductivity of sodium oxalate and can effectively reduce the decomposition potential of sodium oxalate. For example, after adding SuperP, the decomposition voltage of sodium oxalate can be reduced from about 4.4V to about 4.1V. And SuperP is also relatively cheap, which is conducive to reducing material costs. In addition, the particle size of SuperP is conducive to the application of spray drying, and will not clog the instrument, so the content of SuperP can be flexibly adjusted. The size of the sodium oxalate material obtained by the present invention is at the nanometer level, the size is significantly reduced, and it is evenly mixed with SuperP, and combined into a uniform spherical structure.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] (1) The present invention successfully reduces the size and structure of sodium oxalate particles through an innovative preparation process, and achieves a highly uniform composite of sodium oxalate and SuperP at the nanoscale. Compared with mechanical mixing, this method avoids agglomeration or unevenness, greatly improves the conductivity of sodium oxalate, and reduces the decomposition voltage of sodium oxalate. (2) The sodium oxalate and SuperP used in the present invention are low-priced, which improves material utilization while reducing production costs. (3) The particle size of sodium oxalate is greatly reduced, which increases its specific surface area and reaction activity, and is beneficial to ion transport in the subsequent pre-sodiumization process. Its application in sodium ion hybrid capacitors can effectively replenish the consumption of sodium ions in the electrolyte and improve the electrochemical performance of the capacitor. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a scanning electron microscope photograph of commercially available sodium oxalate;

[0022] Figure 2 This is a scanning electron microscope photograph of the final product obtained in Example 1. DETAILED DESCRIPTION

[0023] The technical solution of the present invention is described below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto:

[0024] Example 1

[0025] A method for preparing a sodium-supplementing material for a sodium-ion hybrid capacitor comprises the following steps:

[0026] Step 1: Dissolve 7.5 g of original sodium oxalate in 500 ml of deionized water and stir in a beaker;

[0027] Step 2: Add 10 ml of anhydrous ethanol to the solution treated in step 1 and stir;

[0028] Step 3, adding 1.5 g of SuperP to the solution treated in step 2;

[0029] Step 4: Stir the solution treated in step 3 for 1 hour, and then sonicate for 1 hour;

[0030] Step 5: The solution treated in step 4 was spray dried at a feed rate of 15 ml / min, with an inlet air temperature of 230°C and an exhaust air temperature of 110°C. A sodium oxalate and SuperP composite sodium ion hybrid capacitor sodium replenishing material was collected. The decomposition voltage of the obtained sodium replenishing material was approximately 4.1 V.

[0031] Example 2

[0032] A method for preparing a sodium-supplementing material for a sodium-ion hybrid capacitor comprises the following steps:

[0033] Step 1: Dissolve 7.5 g of original sodium oxalate in 500 ml of deionized water and stir in a beaker;

[0034] Step 2: Add 25 ml of anhydrous ethanol to the solution treated in step 1 and stir;

[0035] Step 3, adding 1.5 g of SuperP to the solution treated in step 2;

[0036] Step 4: Stir the solution treated in step 3 for 1 hour, and then sonicate for 1 hour;

[0037] Step 5: spray-dry the solution treated in step 4 at a feed rate of 15 ml / min, an inlet air temperature of 230° C., and an exhaust air temperature of 110° C. to obtain a sodium oxalate and SuperP composite sodium ion hybrid capacitor sodium replenishing material.

[0038] Example 3

[0039] Step 1: Dissolve 9 g of original sodium oxalate in 800 ml of deionized water and stir in a beaker;

[0040] Step 2: Add 15 ml of anhydrous ethanol to the solution treated in step 1 and stir;

[0041] Step 3, adding 0.5g SuperP to the solution treated in step 2;

[0042] Step 4: Stir the solution treated in step 3 for 1.5 hours, and then sonicate for 1.5 hours;

[0043] Step 5: spray-dry the solution treated in step 4 at a feed rate of 20 ml / min, an inlet air temperature of 200° C., and an exhaust air temperature of 110° C. to obtain a sodium oxalate and SuperP composite sodium ion hybrid capacitor sodium replenishing material.

[0044] Example 4

[0045] Step 1: Dissolve 6 g of original sodium oxalate in 500 ml of deionized water and stir in a beaker;

[0046] Step 2: Add 5 ml of anhydrous ethanol to the solution treated in step 1 and stir;

[0047] Step 3, adding 0.5g SuperP to the solution treated in step 2;

[0048] Step 4: Stir the solution treated in step 3 for 1 hour, and then sonicate for 1 hour;

[0049] Step 5: spray-dry the solution treated in step 4 at a feed rate of 10 ml / min, an inlet air temperature of 200° C., and an exhaust air temperature of 110° C. to obtain a sodium oxalate and SuperP composite sodium ion hybrid capacitor sodium replenishing material.

[0050] Example 5

[0051] Step 1: Dissolve 6 g of original sodium oxalate in 1000 ml of deionized water and stir in a beaker;

[0052] Step 2: Add 5 ml of anhydrous ethanol to the solution treated in step 1 and stir;

[0053] Step 3, adding 0.5g SuperP to the solution treated in step 2;

[0054] Step 4: Stir the solution treated in step 3 for 1 hour, and then sonicate for 1 hour;

[0055] Step 5: spray-dry the solution treated in step 4 at a feed rate of 10 ml / min, an inlet air temperature of 220° C., and an exhaust air temperature of 100° C. to obtain a sodium oxalate and SuperP composite sodium ion hybrid capacitor sodium replenishing material.

[0056] Example 6

[0057] Step 1: Dissolve 6 g of original sodium oxalate in 600 ml of deionized water and stir in a beaker;

[0058] Step 2: Add 6 ml of anhydrous ethanol to the solution treated in step 1 and stir;

[0059] Step 3, adding 0.5g SuperP to the solution treated in step 2;

[0060] Step 4: Stir the solution treated in step 3 for 1 hour, and then sonicate for 1 hour;

[0061] Step 5: spray-dry the solution treated in step 4 at a feed rate of 15 ml / min, an inlet air temperature of 230° C., and an exhaust air temperature of 100° C. to obtain a sodium oxalate and SuperP composite sodium ion hybrid capacitor sodium replenishing material.

[0062] Example 7

[0063] Step 1: Dissolve 6 g of original sodium oxalate in 900 ml of deionized water and stir in a beaker;

[0064] Step 2: Add 10 ml of anhydrous ethanol to the solution treated in step 1 and stir;

[0065] Step 3, adding 0.5g SuperP to the solution treated in step 2;

[0066] Step 4: Stir the solution treated in step 3 for 1 hour, and then sonicate for 1 hour;

[0067] Step 5: spray-dry the solution treated in step 4 at a feed rate of 20 ml / min, an inlet air temperature of 220° C., and an exhaust air temperature of 110° C. to obtain a sodium oxalate and SuperP composite sodium ion hybrid capacitor sodium replenishing material.

[0068] The above embodiments are only for illustrating the technical concept and features of the present invention. Its purpose is to enable people familiar with this technology to understand the content of the present invention and implement it. It cannot be used to limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a sodium-supplementing material for a sodium-ion hybrid capacitor, characterized in that: Anhydrous ethanol is added to the aqueous solution of sodium oxalate, and Super P is added after thorough mixing. The solution after the Super P is thoroughly dispersed is spray-dried to obtain the sodium supplement material for sodium ion hybrid capacitors.

2. The method for preparing a sodium-supplementing material for a sodium-ion hybrid capacitor according to claim 1, wherein: The mass ratio of sodium oxalate to Super P is 1-20:

1.

3. The method for preparing a sodium-supplementing material for a sodium ion hybrid capacitor according to claim 2, wherein: The volume ratio of deionized water to anhydrous ethanol is 10-200:

1.

4. The method for preparing a sodium-supplementing material for a sodium ion hybrid capacitor according to claim 1, wherein: When Super P is fully dispersed, stirring and ultrasonication are performed respectively, and the stirring and ultrasonication time are respectively not less than 1 hour.

5. The method for preparing a sodium-supplementing material for a sodium-ion hybrid capacitor according to claim 1, wherein: The spray drying is carried out using a spray dryer with a feed rate of 10-30 ml / min, an air inlet temperature of 200° C.-250° C., and an exhaust air temperature of 80° C.-150° C.

6. A method for preparing a sodium-supplementing material for a sodium-ion hybrid capacitor according to any one of claims 1 to 5, characterized in that: The sodium oxalate is a columnar structure.

7. A sodium-supplementing material for sodium ion hybrid capacitors obtained by the preparation method according to any one of claims 1 to 6.

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