CN111261938A - Electrolyte additive for sodium ion battery using prussian blue and analogues thereof as positive electrode material and application of electrolyte additive - Google Patents

Abstract

The invention discloses an electrolyte additive for a sodium ion battery taking prussian blue and analogues thereof as a positive electrode material and application thereof, belongs to the field of secondary batteries and also belongs to the technical field of energy materials. Compared with a control sample which is not added, the battery using the additive provided by the invention has the advantages that the first discharge capacity is stably improved under the condition that the charge-discharge multiplying power is 1C, the cycle stability is greatly improved, and the cycle capacity retention rate can be improved by 15.1% after 300 cycles.

Description

A kind of electrolyte for sodium ion battery using Prussian blue and its analogs as positive electrode materials Liquid Additives and Their Applications

technical field

The invention belongs to the field of secondary batteries and the technical field of energy materials, and particularly relates to an electrolyte additive for sodium ion batteries using Prussian blue and the like as positive electrode materials and applications thereof.

Background technique

In recent years, lithium-ion batteries have received extensive and in-depth research and development. Because of their high energy density, long life, and no memory effect, they have occupied major markets such as portable electronic devices and electric vehicles, and have shown great promise in the large-scale energy storage market. Great prospects. However, due to the limited global lithium resource reserves and its high manufacturing cost, its development in the large-scale energy storage market has been severely restricted. To this end, research and development of new batteries with abundant resource reserves and low cost can well meet the challenges of large-scale energy storage market development. Compared with lithium, sodium has the advantages of abundant reserves and lower refining costs, and the two are in the same main group, showing similar chemical properties and having similar electrode potentials. If a new type of sodium-ion battery can be researched and developed to enhance its battery performance and develop in the field of large-scale energy storage, sodium-ion battery will have a greater cost advantage than lithium-ion battery. Therefore, exploring sodium-ion batteries with high capacity and long cycle life has become a research hotspot in this field. Among them, Prussian blue and its analog materials have attracted people's attention because of their high theoretical capacity, but the prepared materials themselves contain more bound water, which seriously restricts their structural stability and affects the performance of batteries. And the battery as a whole system, the role of the electrolyte is extremely important. At present, the electrolyte used in sodium-ion batteries mainly draws on the research results of commercial lithium-ion batteries, and carbonate-based electrolytes are usually used for research, which lacks further in-depth research. For Prussian blue and its analog electrode materials, research and development of corresponding matching electrolytes to maximize their performance will be an indispensable link for the commercialization of sodium-ion batteries in the future.

SUMMARY OF THE INVENTION

In order to solve the problem that when Prussian blue and its analogs existing in the prior art are used as positive electrode materials for sodium ion batteries, it is difficult to remove bound water and the surface of electrode materials is alkaline. At the same time, the Prussian blue material itself is sensitive to the alkaline environment and is easily etched and destroys the material structure, which will have a great adverse effect on the working performance of the battery. The electrolyte additive for sodium ion battery using Prussian blue and its analogs as the positive electrode material and its application, the technical scheme is as follows:

First, the present invention provides an electrolyte additive for sodium ion batteries using Prussian blue and the like as positive electrode materials, including at least one metal salt with Lewis acidity.

The metal salt with Lewis acidity is one or more of anhydrous antimony chloride, antimony fluoride, niobium chloride, zinc chloride, tin chloride, chromium chloride, aluminum chloride, and titanium chloride .

Secondly, the present invention provides the application of the above-mentioned electrolyte additive for sodium ion batteries using Prussian blue and its analogs as positive electrode materials.

The application of the electrolyte additive for sodium ion batteries using Prussian blue and its analogs as positive electrode materials, as electrolyte additives, is added to the basic electrolyte of sodium ion batteries using Prussian blue and its analogs as positive electrode materials.

The anode material of the sodium ion battery is one of Prussian blue and the like.

The base electrolyte includes sodium salt and organic solvent.

The sodium salt includes one or both of NaClO ₄ and NaPF ₆ .

The organic solvent is a carbonate organic solvent.

The carbonate organic solvent includes one of ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC) and fluoroethylene carbonate (FEC) or two or more.

The electrolyte additive accounts for 0.001%-20% by mass of the basic electrolyte.

beneficial effect

The electrolyte additive of the present invention can neutralize the alkalinity of the surface of the electrode material of Prussian blue and the like, and reduce the etching effect on the electrode material itself; at the same time, during the charging and discharging process, the bound water of the positive electrode material is The hydrated sodium ion is released, and the electrolyte additive of the present invention can react with it to capture the water molecules in the hydrated sodium ion to form a stable compound. It can prevent water molecules from decomposing and producing gas under high voltage, and avoid entering the material again in the form of large-sized hydrated sodium ions, squeezing the lattice, destroying the structure, and causing a cycle process. cracks in.

The use of the electrolyte additive of the present invention can effectively improve the working performance of the battery through the above-mentioned dual functions of neutralizing alkalinity and "locking" water molecules. At a charge-discharge rate of 1C, the initial discharge capacity is stably improved, and the cycle stability can be greatly improved. After 300 cycles, the cycle capacity retention rate can be increased by 15.1%.

Description of drawings

Fig. 1 is the performance curve of the battery prepared in Example 1;

Fig. 2 is the performance curve of the battery prepared in Example 2;

FIG. 3 is the performance curve of the battery prepared in Example 3. FIG.

Detailed ways

Example 1

(1) Electrolyte preparation

Ethylene carbonate (EC), diethyl carbonate (DEC) and fluoroethylene carbonate (FEC) were mixed according to the volume ratio EC:DEC:FEC=48:48:4, and sodium perchlorate (NaClO ₄ ) dissolved to a molar concentration of 1 mol/L.

(2) The Prussian blue material was used as the working electrode, and the sodium metal sheet was used as the counter electrode. The battery was assembled with the above electrolyte as a comparison sample, and its electrochemical performance was tested.

Add the additive provided by the present invention:

According to the method of the comparative example, the electrolyte is prepared, the battery is assembled, and the performance is tested. 0.5%.

The test performance curve is shown in Figure 1. It can be seen that under the charge-discharge rate of 1C, after adding the additive provided by the present invention, the initial discharge capacity is increased from 104.0mAh/g to 111.8mAh/g, and the cycle stability can be greatly improved. After 300 cycles, the cycle capacity retention rate improved from 75.4% to 82.7%, an increase of 7.3%.

Example 2

(1) Electrolyte preparation

Ethylene carbonate (EC), propylene carbonate (PC) and fluoroethylene carbonate (FEC) were mixed according to the volume ratio EC:PC:FEC=47:47:6, and sodium perchlorate (NaClO4) was added to dissolve to a molar concentration of 1 mol/L.

(2) The Prussian blue material was used as the working electrode, and the sodium metal sheet was used as the counter electrode. The battery was assembled with the above electrolyte as a comparison sample, and its electrochemical performance was tested.

Add the additive provided by the present invention:

According to the method of the comparative example, the electrolyte is prepared, the battery is assembled, and the performance test is performed. 0.8%.

The test performance curve is shown in Figure 2. It can be seen that at a charge-discharge rate of 1C, the initial discharge capacity is increased from 104.7mAh/g to 108.2mAh/g, and the cycle stability can be greatly improved. After 300 cycles, the cycle capacity The retention rate improved from 81.1% to 93.8%, an increase of 12.7%.

Example 3

(1) Electrolyte preparation

Propylene carbonate (PC) and fluoroethylene carbonate (FEC) were mixed in a volume ratio of PC:FEC=95:5, and sodium perchlorate (NaClO4) was added to dissolve to a molar concentration of 1 mol/L.

(2) The Prussian blue material was used as the working electrode, and the sodium metal sheet was used as the counter electrode. The battery was assembled with the above electrolyte as a comparison sample, and its electrochemical performance was tested.

Add the additive provided by the present invention:

According to the method of the comparative example, the electrolyte is prepared, the battery is assembled, and the performance is tested. 1.0%.

The test performance curve is shown in Figure 3. It can be seen that under the charge-discharge rate of 1C, the initial discharge capacity is increased from 101.4mAh/g to 102.6mAh/g, and the cycle stability can be greatly improved. After 300 cycles, the cycle capacity The retention rate improved from 76.3% to 91.4%, an increase of 15.1%.

Example 4

(1) Electrolyte preparation

Ethylene carbonate (EC), diethyl carbonate (DEC) and fluoroethylene carbonate (FEC) were mixed according to the volume ratio EC:DEC:FEC=48:48:4, and sodium perchlorate (NaClO ₄ ) dissolved to a molar concentration of 1 mol/L.

(2) The Prussian blue material was used as the working electrode, and the sodium metal sheet was used as the counter electrode. The battery was assembled with the above electrolyte as a comparison sample, and its electrochemical performance was tested.

Add the additive provided by the present invention:

According to the method of the comparative example, the electrolyte is prepared, the battery is assembled, and the performance is tested. The difference is: in the preparation process of the electrolyte, the additive of the present invention is additionally added to dissolve, and aluminum chloride and titanium chloride are selected and mixed at a mass ratio of 1:1. As an additive, the added mass is 0.001% of the electrolyte mass.

When the charge-discharge rate is 1C, after adding the additive provided by the present invention, the initial discharge capacity is increased from 104.0mAh/g to 105.8mAh/g, and the cycle stability can be improved to a certain extent. After 300 cycles, the cycle capacity retention rate An improvement of 2.0% from 75.4% to 77.4%.

Example 5

(1) Electrolyte preparation

Ethylene carbonate (EC), propylene carbonate (PC) and fluoroethylene carbonate (FEC) were mixed according to the volume ratio EC:PC:FEC=47:47:6, and sodium perchlorate (NaClO4) was added to dissolve to a molar concentration of 1 mol/L.

(2) The Prussian blue material was used as the working electrode, and the sodium metal sheet was used as the counter electrode. The battery was assembled with the above electrolyte as a comparison sample, and its electrochemical performance was tested.

Add the additive provided by the present invention:

According to the method of the comparative example, the electrolyte is prepared, the battery is assembled, and the performance is tested. The mass ratio of 1:2:3 is mixed as an additive, and the added mass is 20% of the mass of the electrolyte.

At a charge-discharge rate of 1C, the initial discharge capacity increased from 104.7mAh/g to 107.2mAh/g, and the cycle stability could be greatly improved. After 300 cycles, the cycle capacity retention rate improved from 81.1% to 92.1% , an increase of 11.0%.

Claims (10)

1. A sodium ion battery electrolyte additive with Prussian blue and the like as positive electrode material, characterized in that: at least one metal salt with Lewis acidity is included. 2. The electrolyte additive for sodium ion batteries using Prussian blue and the like as positive electrode material according to claim 1, wherein the metal salt with Lewis acidity is anhydrous antimony chloride, antimony fluoride , one or more of niobium chloride, zinc chloride, tin chloride, chromium chloride, aluminum chloride and titanium chloride. 3. The application of the electrolyte additive for sodium ion batteries according to any one of claims 1 or 2 with Prussian blue and the like as positive electrode material. 4. application according to claim 3, it is characterized in that: described with Prussian blue and its analogs as the electrolyte additive for sodium ion battery of positive electrode material, as electrolyte additive, add and dissolve into with Prussian blue and its analogues. Analogues are used as cathode materials in the base electrolyte of sodium-ion batteries. 5 . The application according to claim 4 , wherein the anode material for the sodium ion battery is one of Prussian blue and the like. 6 . 6. The application according to claim 4, wherein the basic electrolyte comprises sodium salt and organic solvent. 7. application according to claim 6 is characterized in that: described sodium salt comprises one or both in NaClO ₄ and NaPF ₆ . 8. The application according to claim 6, wherein the organic solvent is a carbonate organic solvent. 9. application according to claim 8 is characterized in that: described carbonate organic solvent comprises ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate ( One or more of DEC) and fluoroethylene carbonate (FEC). 10 . The application according to claim 4 , wherein the electrolyte additive accounts for 0.001%-20% by mass of the basic electrolyte. 11 .

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