Synthesis method of sodium supplementing material for sodium ion hybrid capacitor

Abstract

The invention belongs to the technical field of hybrid capacitors, and particularly relates to a synthesis method of a sodium supplementing material for a sodium ion hybrid capacitor. The sodium supplementing material is prepared by fully dispersing commercially available sodium oxalate into deionized water, and then carrying out spray drying to obtain sodium oxalate with a nanoscale size. Through the unique preparation process, the size of the sodium oxalate particles is successfully reduced, the specific surface area and the utilization rate of the sodium oxalate are improved, and the decomposition voltage of the sodium oxalate is reduced. The electrolyte is mixed with a sodium ion mixed capacitor positive electrode material and charged to a certain potential, so that consumption of sodium ions in the electrolyte can be effectively supplemented, and the electrochemical performance of the capacitor is improved. The method is simple and suitable for large-scale preparation, and has certain commercial potential.

Description

Technical Field

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

[0002] As a new type of energy storage device, sodium ion hybrid capacitors are composed of capacitor-type positive electrode materials and battery-type negative electrode materials. They have many advantages such as high energy density, high power density and long cycle life. In addition, since the Na element does not react with the Al current collector, low-cost Al current collectors can be used to replace expensive Cu current collectors, thereby significantly reducing R&D and application costs, and further broadening the commercial application prospects of sodium ion hybrid capacitors. However, when sodium ion hybrid capacitors are charged and discharged for the first time, the sodium ions in the electrolyte will undergo irreversible solid interface film reactions on the surface of the negative electrode, causing a large loss of active substances, thereby reducing the initial coulombic efficiency, energy density and cycle performance. To improve this situation, researchers have developed a pre-sodiumization technology suitable for sodium storage electrode materials, aiming to improve the electrochemical performance of sodium ion hybrid capacitors.

[0003] Currently, pre-sodiumization technologies mainly include two strategies: positive electrode sodium replenishment and negative electrode sodium replenishment. The negative electrode sodium replenishment method effectively compensates for the sodium ions consumed by the irreversible formation of the solid electrolyte interface (SEI) by pre-introducing metallic sodium or its compounds into the negative electrode material, thereby significantly improving the reversible capacity of sodium-ion hybrid capacitors and optimizing their electrochemical performance. Depending on the sodium replenishment method, negative electrode sodium replenishment technology can be further subdivided into: direct contact with metallic sodium, chemical sodium replenishment agent method, and electrochemical short-circuit pre-sodium method. However, these methods usually require additional processing steps on the negative electrode side. In contrast, positive electrode sodium replenishment technology is gradually developing into a new sodium replenishment strategy with more practical value due to its advantages such as simple operation and flexible process. Positive electrode sodium replenishment involves directly mixing and doping high-sodium-content compounds with positive electrode active materials during the slurry preparation process to prepare sodium-rich electrode materials, which can effectively increase the sodium content of the positive electrode active material. The research and development of new sodium replenishment materials has realistic application prospects. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for synthesizing a sodium-supplementing material for sodium ion hybrid capacitors, which can effectively solve the defects of sodium oxalate as a sodium-supplementing material and expand its practical application.

[0005] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0006] A method for synthesizing a sodium-supplementing material for a sodium-ion hybrid capacitor is disclosed. The sodium-supplementing material is prepared by fully dispersing commercially available sodium oxalate in deionized water, followed by spray drying to obtain sodium oxalate having a nanometer size.

[0007] Wherein, commercially available sodium oxalate is added into deionized water and stirred for 1-5 hours for dispersion.

[0008] The feed rate for mist drying is 10ml / min-30ml / min.

[0009] Furthermore, the inlet air temperature of the spray drying is 200-250°C.

[0010] Furthermore, the outlet air temperature of the spray drying is 80-150°C.

[0011] The sodium oxalate particles obtained after spray drying have a spherical structure.

[0012] From the perspectives of environmental friendliness, cost, and battery capacity, sodium oxalate is a satisfactory sodium supplement reagent with a theoretical capacity of up to 400 mAh g -1 . Sodium oxalate can efficiently release sodium ions during the decomposition process, effectively compensating for the sodium source consumed by the formation of the SEI film, thereby significantly improving the electrochemical performance of sodium ion hybrid capacitors. However, in actual applications, sodium oxalate crystals with larger particle sizes usually have a higher decomposition voltage, which may exceed the stable voltage window of the battery and affect its electrochemical stability. At the same time, due to its small specific surface area and poor conductivity, sodium oxalate is difficult to fully decompose, resulting in a decrease in the utilization rate of active substances. The above defects limit the practical application of sodium oxalate as a sodium supplement reagent.

[0013] The present invention is based on practical application and future large-scale application, and uses commercially available sodium oxalate as a raw material, which is low in cost. However, commercially available sodium oxalate not only has the aforementioned problem of large particles (most of which are larger than 10 μm in length), but also has a certain degree of agglomeration between the sodium oxalate particles, further limiting its application.

[0014] By using the method of the present invention, the particle size of the obtained sodium oxalate particles is significantly reduced, and the sodium oxalate particles are assembled into a spherical structure with a large specific surface area, which can effectively improve the utilization efficiency of sodium oxalate and reduce its decomposition potential.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] The present invention successfully reduces the size of sodium oxalate particles through a unique preparation process, increases the specific surface area and utilization rate of sodium oxalate, and reduces the decomposition voltage of sodium oxalate. The optimized sodium oxalate decomposition capacity can reach 358mAhg -1 This demonstrates the effectiveness of this method. Mixing it with the positive electrode material of a sodium-ion hybrid capacitor and charging it to a certain potential effectively replenishes the sodium ions consumed in the electrolyte, improving the electrochemical performance of the capacitor. The method is simple, suitable for large-scale production, and has considerable commercial potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a scanning electron microscope image of the original commercial sodium oxalate product;

[0018] Figure 2 This is a scanning electron microscope photograph of the final product obtained in Example 1. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0020] Example 1

[0021] A method for synthesizing a sodium-supplementing material for a sodium-ion hybrid capacitor comprises the following steps:

[0022] Step 1: Dissolve 7.5 g of original sodium oxalate in 500 ml of deionized water;

[0023] Step 2: Stir the solution treated in step 1 for 1 hour, and then sonicate for 1 hour;

[0024] Step 3: spray-dry the solution treated in step 2 at a feed rate of 15 ml / min, an inlet air temperature of 230°C, and an exhaust air temperature of 110°C to collect sodium oxalate supplementary material with a smaller particle size. The decomposition capacity of the obtained sodium oxalate is 358 mAh g -1 about.

[0025] Example 2

[0026] A method for synthesizing a sodium-supplementing material for a sodium-ion hybrid capacitor comprises the following steps:

[0027] Step 1: Dissolve 6 g of original sodium oxalate in 500 ml of deionized water;

[0028] Step 2, stirring the solution treated in step 1 for 1 hour;

[0029] Step 3: spray-dry the solution treated in step 2 at a feed rate of 15 ml / min, a cavity temperature of the spray dryer of 230° C., and a material collection temperature of 110° C. to obtain a sodium oxalate sodium supplement material with a smaller particle size.

[0030] Example 3

[0031] A method for synthesizing a sodium-supplementing material for a sodium-ion hybrid capacitor comprises the following steps:

[0032] Step 1: Dissolve 9 g of original sodium oxalate in 600 ml of deionized water;

[0033] Step 2: Stir the solution treated in step 1 for 2 hours;

[0034] Step 3: spray-dry the solution treated in step 2 at a feed rate of 20 ml / min, a cavity temperature of the spray dryer of 200° C., and a material collection temperature of 120° C. to obtain a sodium oxalate sodium supplement material with a smaller particle size.

[0035] Example 4

[0036] A method for synthesizing a sodium-supplementing material for a sodium-ion hybrid capacitor comprises the following steps:

[0037] Step 1: Dissolve 6 g of original sodium oxalate in 600 ml of deionized water;

[0038] Step 2, stirring the solution treated in step 1 for 1 hour;

[0039] Step 3: spray-dry the solution treated in step 2 at a feed rate of 25 ml / min, an inlet air temperature of 230° C., and an exhaust air temperature of 110° C. to collect a sodium oxalate sodium supplement material with a smaller particle size.

[0040] Example 5

[0041] A method for synthesizing a sodium-supplementing material for a sodium-ion hybrid capacitor comprises the following steps:

[0042] Step 1: Dissolve 7 g of original sodium oxalate in 300 ml of deionized water;

[0043] Step 2: Stir the solution treated in step 1 for 2 hours;

[0044] Step 3: spray-dry the solution treated in step 2 at a feed rate of 10 ml / min, a chamber temperature of the spray dryer of 220° C., and an exhaust temperature of 110° C. to collect a sodium oxalate sodium supplement material with a smaller particle size.

[0045] Example 6

[0046] A method for synthesizing a sodium-supplementing material for a sodium-ion hybrid capacitor comprises the following steps:

[0047] Step 1: Dissolve 10 g of original sodium oxalate in 500 ml of deionized water;

[0048] Step 2: Stir the solution treated in step 1 for 1.5 hours;

[0049] Step 3: spray-dry the solution treated in step 2 at a feed rate of 15 ml / min, an inlet air temperature of 230° C., and an exhaust air temperature of 110° C. to collect sodium oxalate sodium supplement material with a smaller particle size.

[0050] Example 7

[0051] A method for synthesizing a sodium-supplementing material for a sodium-ion hybrid capacitor comprises the following steps:

[0052] Step 1: Dissolve 6 g of original sodium oxalate in 400 ml of deionized water;

[0053] Step 2: Stir the solution treated in step 1 for 2 hours;

[0054] Step 3: spray-dry the solution treated in step 2 at a feed rate of 20 ml / min, an inlet air temperature of 200° C., and an exhaust air temperature of 110° C. to collect sodium oxalate sodium-supplementing material with a smaller particle size.

Claims

1. A method for synthesizing a sodium-supplementing material for a sodium-ion hybrid capacitor, characterized in that: The sodium supplement material is prepared by fully dispersing commercially available sodium oxalate into deionized water, and then spray drying the obtained sodium oxalate to obtain a nanometer-sized size.

2. The method for synthesizing the sodium-supplementing material for sodium ion hybrid capacitors according to claim 1, wherein: Commercially available sodium oxalate was added to deionized water and stirred for 1-5 hours for dispersion.

3. The method for synthesizing the sodium-supplementing material for sodium ion hybrid capacitors according to claim 2, wherein: The feed rate for spray drying was 10 ml / min-30 ml / min.

4. The method for synthesizing the sodium-supplementing material for sodium ion hybrid capacitors according to claim 3, wherein: The inlet air temperature for spray drying is 200-250℃.

5. The method for synthesizing the sodium-supplementing material for sodium ion hybrid capacitors according to claim 4, wherein: The outlet air temperature of spray drying is 80-150℃.

6. The method for synthesizing the sodium-supplementing material for sodium ion hybrid capacitors according to any one of claims 1 to 5, wherein: The sodium oxalate nanoparticles obtained after spray drying assembled into a spherical structure.

7. The method for synthesizing the sodium-supplementing material for sodium ion hybrid capacitors according to claim 6, wherein: The commercially available sodium oxalate material has a columnar structure.

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