CN114639878A - Aqueous lithium ion battery electrolyte based on oligomer and application thereof - Google Patents

Abstract

The invention discloses an aqueous lithium ion battery electrolyte based on oligomer, which comprises oligomer solute, electrolyte and water; wherein the oligomeric solute is selected from oligomers of pyrrole, aniline or thiophene; the electrolyte is a lithium-containing soluble salt. The electrolyte has the characteristics of high voltage window and good cycling stability, and is suitable for high-pressure water system lithium ion batteries. The invention also discloses application of the electrolyte.

Description

An oligomer-based aqueous lithium-ion battery electrolyte and its application

technical field

The present invention relates to the field of aqueous ion batteries. More specifically, it relates to an oligomer-based aqueous lithium-ion battery electrolyte and its application.

Background technique

Although commercial lithium-ion batteries have many advantages such as high energy density, high cycle stability, and high energy efficiency, the use of organic-based electrolytes with high cost and poor safety still hinders their large-scale energy storage applications. In view of this, the development of aqueous electrolytes with high safety factor, easy preparation, and high ionic conductivity has become an ideal choice for large-scale energy storage. An aqueous battery refers to a secondary battery that uses water as an electrolyte solvent. Compared with organic electrolyte batteries, aqueous batteries have the advantages of high safety, environmental friendliness, and high ionic conductivity. Therefore, aqueous batteries have greater application prospects in large-scale electrical energy storage in the future. At present, water-based batteries are mainly limited by the shortcomings of narrow window voltage, serious electrode side reactions, and poor cycle stability. Zinc batteries, etc.), and a lot of research has been done on their anode and cathode materials, electrolytes, and energy storage mechanisms.

Unlike organic electrolytes, aqueous electrolytes have narrow stable potential windows, and water splitting must be carefully considered when selecting electrode active materials for lithium-ion water batteries. In principle, the reaction potential of materials such as LiCoO ₂ , LiMn ₂ O ₄ , LiNi _x Co _1-x O ₂ , LiFePO ₄ is before the water splitting potential, so they can be used as cathode materials for lithium-ion aqueous batteries. Theoretically, within the voltage range of hydrogen evolution and oxygen evolution, a low-potential lithium-ion-accepting negative electrode and a high-potential lithium-ion-providing positive electrode can be combined to form an aqueous lithium-ion battery.

In 1994, the first aqueous lithium-ion battery was reported, which used VO ₂ and LiMn ₂ O ₄ as the negative and positive electrodes, respectively, and 5M LiNO ₃ as the electrolyte. However, the electrochemical window of the water-based lithium-ion battery is narrow, which restricts its further large-scale application. In response to this problem, a new type of "water-in-salt" electrolyte has been adopted in recent years, which can make the electrochemical window of the water-based lithium-ion battery reach 3.0V (1.9–4.9V vs. Li ⁺ /Li), which is comparable to organic electrolytes, and LiTFSI is used as the lithium salt. When the positive electrode is polarized, TFSI ^- will be reduced before water molecules to form a layer Similar to the SEI film in the organic electrolyte system, it helps to improve the open circuit voltage and electrochemical performance of the battery.

SUMMARY OF THE INVENTION

The first object of the present invention is to provide an oligomer-based aqueous lithium-ion battery electrolyte, which has the characteristics of high voltage window and good cycle stability, and is suitable for high-pressure aqueous lithium-ion batteries.

The second object of the present invention is to provide an application of an oligomer-based aqueous lithium-ion battery electrolyte in an electrochemical energy storage device.

The third object of the present invention is to provide an electrochemical energy storage device.

For reaching above-mentioned first purpose, the present invention adopts following technical scheme:

An oligomer-based aqueous lithium-ion battery electrolyte electrolyte, comprising an oligomer solute, an electrolyte and water; wherein,

The oligomer solute is selected from oligomers of pyrrole, aniline or thiophene;

The electrolyte is a lithium-containing soluble salt.

In the present invention, it is found that these selected oligomer solutes are preferentially adsorbed on the surface of the electrode. When free water molecules in the electrolyte contact the electrode surface, the electrode material and the above-mentioned oligomer solute are preferentially reacted with electron gain and loss. The water only breaks down when the voltage is higher or lower. In addition, the heteroatoms in the above-mentioned oligomers interact with free water molecules through hydrogen bonding, which can overcome the preferential reaction characteristics of water molecules on the electrode surface. Combining the above two functions, the electrochemical stability window of the electrolyte is broadened. On the other hand, the above-mentioned oligomer solute encapsulates the electrode material in situ, which avoids the destruction of the crystal structure of the material and suppresses the side reactions on the surface, and at the same time improves the electronic conductivity and ion transport performance of the material.

Further, the degree of polymerization of the oligomer solute is 2-10.

Further, the oligomer solute is obtained by adding pyrrole, aniline or thiophene monomer into an aqueous solution containing an oxidant, and after the reaction, the supernatant is taken and centrifuged. Under this condition, the voltage window is higher and the cycling stability is better.

Further, the oxidant is selected from one or more of ferric chloride and ammonium persulfate.

Further, in the aqueous solution of the oxidant, the concentration of the oxidant is 0.0005-0.005M. Exemplarily, the concentration of the oxidant includes, but is not limited to, 0.005M, 0.001-0.005M, 0.0005M, 0.0005-0.001M, and the like.

Further, the concentration of the electrolyte in the electrolyte is 1-21M. Exemplarily, the concentration of the electrolyte includes, but is not limited to, 10-21M, 10M, 21M, and the like.

Further, the concentration of the oligomer solute is 10 ^-6 to 1M. Exemplarily, the concentration of the oligomeric solute includes, but is not limited to, 10 ^-6 M, 10 ^-3 M, 1 M, and the like.

Further, the lithium-containing soluble salt is selected from one of lithium sulfate, lithium nitrate, lithium acetate, lithium bistrifluoromethanesulfonimide and lithium bisfluorosulfonimide.

In order to achieve the above second object, the present invention provides the application of the electrolyte solution described in the first object above in an electrochemical energy storage device.

In order to achieve the above-mentioned third object, the present invention provides an electrochemical energy storage device, which includes the electrolyte according to the first object.

Further, the electrochemical energy storage device is an aqueous secondary battery or an aqueous electrochemical supercapacitor or an organic combination of the two.

Further, the water-based secondary battery is selected from water-based lithium-ion batteries.

Further, the aqueous lithium-ion battery includes a positive electrode and a negative electrode; wherein, the positive electrode material is selected from lithium manganate, lithium iron phosphate or ternary material NCM523; the negative electrode material is selected from titanium dioxide or lithium titanate.

The beneficial effects of the present invention are as follows:

The electrolyte provided in the present invention is an aqueous electrolyte, which has a high-voltage window and is suitable for high-voltage aqueous lithium-ion batteries. In the application and electrochemical energy storage device provided in the present invention, due to the use of the electrolyte of the present application, the decomposition voltage of the electrolyte is improved and the working temperature is widened, thereby improving the performance and application range of the lithium ion battery, which is an electrochemical The promotion and application of energy storage devices has laid the foundation.

Description of drawings

The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

FIG. 1 shows the cycle performance test results obtained by using the prepared aqueous electrolyte in an aqueous lithium ion battery in Example 1.

FIG. 2 shows the test results of the electrochemically stable voltage window obtained by using the prepared aqueous electrolyte in an aqueous lithium ion battery in Example 2.

Detailed ways

In order to illustrate the present invention more clearly, the present invention will be further described below with reference to the preferred embodiments and accompanying drawings. Similar parts in the figures are denoted by the same reference numerals. Those skilled in the art should understand that the content specifically described below is illustrative rather than restrictive, and should not limit the protection scope of the present invention.

Example 1

The specific composition of the aqueous electrolyte in this example is a solvent oligomer solution, and the electrolyte is lithium bistrifluoromethanesulfonimide. The preparation method is as follows: 1 mL of pyrrole is added to 10 mL of FeCl ₃ aqueous solution with a concentration of 0.0005 M, and after the reaction, 1 mL of pyrrole is added. The relatively clear supernatant is centrifuged, and the obtained clear oligomer solution is mixed with water, and the concentration of the oligomer in the solution is 10 ^-3 M, and the lithium bisfluorosulfonimide is dissolved in the aforementioned oligomer solution, An electrolyte solution with an electrolyte concentration of 21 M was prepared to obtain the aqueous electrolyte solution of this example. The electrochemical window of the aqueous electrolyte prepared in this example was tested by three-electrode linear voltammetry, and the electrochemical stability window of the aqueous electrolyte reached 3.2V.

The aqueous electrolyte of this example is used in an aqueous lithium-ion battery, the positive electrode is lithium manganate, the negative electrode is titanium dioxide, and the positive and negative electrodes are mixed according to the weight ratio of active material/carbon black/PVDF=8/1/1 to make a slurry , the positive electrode material is coated on the titanium foil, and the negative electrode material is coated on the carbon-coated aluminum foil, and is made into an electrode after drying. Then, a lithium-ion battery is assembled, the separator used is a glass fiber GFF separator, and the electrolyte is the aqueous electrolyte of this example. The charge-discharge test was performed at 0.8-2.5V, the current density was 1A/g, and the capacity retention was 94% after 3000 cycles at room temperature.

Example 2

The specific composition of the aqueous electrolyte in this example is a solvent oligomer solution, and the electrolyte is lithium bistrifluoromethanesulfonimide. The preparation method is as follows: 1 mL of pyrrole is added to 10 mL of FeCl ₃ aqueous solution with a concentration of 0.005 M, and after the reaction, 1 mL of pyrrole is added. The relatively clear supernatant is centrifuged, and the obtained clear oligomer solution is mixed with water, and the concentration of the oligomer in the solution is 10 ^-3 M, and the lithium bisfluorosulfonimide is dissolved in the aforementioned oligomer solution, An electrolyte solution with an electrolyte concentration of 21 M was prepared to obtain the aqueous electrolyte solution of this example. The electrochemical window of the aqueous electrolyte prepared in this example was tested by three-electrode linear voltammetry, and the electrochemical stability window of the aqueous electrolyte reached 3.2V.

The aqueous electrolyte of this example is used in an aqueous lithium-ion battery, the positive electrode is lithium manganate, the negative electrode is titanium dioxide, and the positive and negative electrodes are mixed according to the weight ratio of active material/carbon black/PVDF=8/1/1 to make a slurry , the positive electrode material is coated on the titanium foil, and the negative electrode material is coated on the carbon-coated aluminum foil, and is made into an electrode after drying. Then, a lithium-ion battery is assembled, the separator used is a glass fiber GFF separator, and the electrolyte is the aqueous electrolyte of this example. The charge-discharge test was carried out at 0.8-2.5V, the current density was 1A/g, and the capacity retention rate was 91% after 3000 cycles at room temperature.

Example 3

The specific composition of the aqueous electrolyte in this example is a solvent oligomer solution, and the electrolyte is lithium bistrifluoromethanesulfonimide. The preparation method is as follows: 1 mL of pyrrole is added to 10 mL of FeCl ₃ aqueous solution with a concentration of 0.0005 M, and after the reaction, 1 mL of pyrrole is added. The relatively clear supernatant is centrifuged, and the obtained clear oligomer solution is mixed with water, and the concentration of the oligomer in the solution is 10 ^-3 M, and the lithium bisfluorosulfonimide is dissolved in the aforementioned oligomer solution, An electrolyte solution with an electrolyte concentration of 21 M was prepared to obtain the aqueous electrolyte solution of this example. The electrochemical window of the aqueous electrolyte prepared in this example was tested by three-electrode linear voltammetry, and the electrochemical stability window of the aqueous electrolyte reached 3.2V.

The aqueous electrolyte of this example is used in an aqueous lithium-ion battery, the positive electrode is lithium manganate, the negative electrode is lithium titanate, and the positive and negative electrodes are mixed according to the weight ratio of active material/carbon black/PVDF=8/1/1. Slurry, the positive electrode material is coated on the titanium foil, and the negative electrode material is coated on the aluminum foil, and is made into an electrode after drying. Then, a lithium-ion battery is assembled, the separator used is a glass fiber GFF separator, and the electrolyte is the aqueous electrolyte of this example. The charge-discharge test was carried out at 1.5-2.8V, the current density was 1A/g, and the capacity retention rate was 93% after 3000 cycles at room temperature.

Example 4

The specific composition of the aqueous electrolyte in this example is a solvent oligomer solution, and the electrolyte is lithium bistrifluoromethanesulfonimide. The preparation method is as follows: 1 mL of pyrrole is added to 10 mL of FeCl ₃ aqueous solution with a concentration of 0.0005 M, and after the reaction, 1 mL of pyrrole is added. The relatively clear supernatant is centrifuged, and the obtained clear oligomer solution is mixed with water, and the concentration of the oligomer in the solution is 10 ^-3 M, and the lithium bisfluorosulfonimide is dissolved in the aforementioned oligomer solution, An electrolyte solution with an electrolyte concentration of 21 M was prepared to obtain the aqueous electrolyte solution of this example. The electrochemical window of the aqueous electrolyte prepared in this example was tested by three-electrode linear voltammetry, and the electrochemical stability window of the aqueous electrolyte reached 3.2V.

The aqueous electrolyte of this example is used in an aqueous lithium-ion battery, the positive electrode is lithium iron phosphate, the negative electrode is titanium dioxide, and the positive and negative electrodes are mixed according to the weight ratio of active material/carbon black/PVDF=8/1/1 to make a slurry , the positive electrode material is coated on the titanium foil, and the negative electrode material is coated on the carbon-coated aluminum foil, and is made into an electrode after drying. Then, a lithium-ion battery is assembled, the separator used is a glass fiber GFF separator, and the electrolyte is the aqueous electrolyte of this example. The charge-discharge test was performed at 1-2.1V, the current density was 1A/g, and the capacity retention was 95% after 4000 cycles at room temperature.

Example 5

The specific composition of the aqueous electrolyte in this example is a solvent oligomer solution, and the electrolyte is lithium bistrifluoromethanesulfonimide. The preparation method is as follows: 1 mL of pyrrole is added to 10 mL of FeCl ₃ aqueous solution with a concentration of 0.0005 M, and after the reaction, 1 mL of pyrrole is added. The relatively clear supernatant is centrifuged, and the obtained clear oligomer solution is mixed with water, and the concentration of the oligomer in the solution is 10 ^-3 M, and the lithium bisfluorosulfonimide is dissolved in the aforementioned oligomer solution, The aqueous electrolyte of this example was obtained by preparing an electrolyte with an electrolyte concentration of 21M. Three-electrode linear voltammetry was used to test the electrochemical window of the aqueous electrolyte prepared in this example, and the electrochemical stability window of the aqueous electrolyte reached 3.2V.

The aqueous electrolyte of this example is used in an aqueous lithium-ion battery, the positive electrode is lithium iron phosphate, the negative electrode is lithium titanate, and the positive and negative electrodes are mixed according to the weight ratio of active material/carbon black/PVDF=8/1/1. Slurry, the positive electrode material is coated on the titanium foil, and the negative electrode material is coated on the aluminum foil, and is made into an electrode after drying. Then, a lithium-ion battery is assembled, the separator used is a glass fiber GFF separator, and the electrolyte is the aqueous electrolyte of this example. The charge-discharge test was performed at 1-2.1V, the current density was 1A/g, and the capacity retention was 94% after 4000 cycles at room temperature.

Example 6

The specific composition of the aqueous electrolyte in this example is a solvent oligomer solution, and the electrolyte is lithium bistrifluoromethanesulfonimide. The preparation method is as follows: 1 mL of pyrrole is added to 10 mL of FeCl ₃ aqueous solution with a concentration of 0.0005 M, and after the reaction, 1 mL of pyrrole is added. The relatively clear supernatant is centrifuged, and the obtained clear oligomer solution is mixed with water, and the concentration of the oligomer in the solution is 10 ^-3 M, and the lithium bisfluorosulfonimide is dissolved in the aforementioned oligomer solution, An electrolyte solution with an electrolyte concentration of 21 M was prepared to obtain the aqueous electrolyte solution of this example. The electrochemical window of the aqueous electrolyte prepared in this example was tested by three-electrode linear voltammetry, and the electrochemical stability window of the aqueous electrolyte reached 3.2V.

The aqueous electrolyte of this example is used in an aqueous lithium-ion battery, the positive electrode is a ternary material NCM523, the negative electrode is titanium dioxide, and the positive and negative electrodes are mixed according to the weight ratio of active material/carbon black/PVDF=8/1/1 to make a slurry The positive electrode material is coated on the titanium foil, and the negative electrode material is coated on the aluminum foil, and is made into an electrode after drying. Then, a lithium-ion battery is assembled, the separator used is a glass fiber GFF separator, and the electrolyte is the aqueous electrolyte of this example. The charge-discharge test was performed at 1-2.2V, the current density was 1A/g, and the capacity retention was 92% after 3000 cycles at room temperature.

Example 7

The specific composition of the aqueous electrolyte in this example is a solvent oligomer solution, and the electrolyte is lithium bistrifluoromethanesulfonimide. The preparation method is as follows: 1 mL of pyrrole is added to 10 mL of FeCl ₃ aqueous solution with a concentration of 0.0005 M, and after the reaction, 1 mL of pyrrole is added. The relatively clear supernatant is centrifuged, and the obtained clear oligomer solution is mixed with water, and the concentration of the oligomer in the solution is 10 ^-3 M, and the lithium bisfluorosulfonimide is dissolved in the aforementioned oligomer solution, An electrolyte solution with an electrolyte concentration of 21 M was prepared to obtain the aqueous electrolyte solution of this example. The electrochemical window of the aqueous electrolyte prepared in this example was tested by three-electrode linear voltammetry, and the electrochemical stability window of the aqueous electrolyte reached 3.2V.

The aqueous electrolyte of this example is used in an aqueous lithium-ion battery, the positive electrode is a ternary material NCM523, the negative electrode is lithium titanate, and the positive and negative electrodes are mixed according to the weight ratio of active material/carbon black/PVDF=8/1/1. A slurry is formed, the positive electrode material is coated on the titanium foil, the negative electrode material is coated on the aluminum foil, and dried to form an electrode. Then, a lithium-ion battery is assembled, the separator used is a glass fiber GFF separator, and the electrolyte is the aqueous electrolyte of this example. The charge-discharge test was performed at 1.5-2.6V, the current density was 1A/g, and the capacity retention was 90% after 3000 cycles at room temperature.

Example 8

Example 4 was repeated, with the difference that the aqueous electrolyte was changed to lithium bisfluorosulfonimide, the concentration of the electrolyte in the electrolyte was 10M, and other conditions remained unchanged, and the electrochemical stability window of the obtained aqueous electrolyte reached 3V.

The aqueous electrolyte was used in an aqueous lithium-ion battery according to the method of Example 1, and the charge-discharge test was carried out at 0.8-2.5V, the current density was 1A/g, and it was cycled 2000 times at room temperature, and the capacity retention rate was 92%. .

Example 9

Example 4 was repeated, except that the oxidant in the oligomer solute was changed to 0.0005M (NH ₄ ) ₂ S ₂ O ₈ , and other conditions remained unchanged, and the electrochemical stability window of the obtained aqueous electrolyte reached 3.2V.

The aqueous electrolyte was used in an aqueous lithium-ion battery according to the method of Example 1, and the charge-discharge test was carried out at 1-2.5V, the current density was 1A/g, and the cycle was 4000 times at room temperature, and the capacity retention rate was 93%. .

Example 10

Example 4 was repeated, the difference was that the weight ratio of the oligomer solute to water was 2:1, and other conditions remained unchanged, and the electrochemical stability window of the obtained aqueous electrolyte reached 3.2V.

The aqueous electrolyte was used in an aqueous lithium-ion battery according to the method of Example 1, and the charge-discharge test was carried out at 0.8-2.6V, the current density was 1A/g, the cycle was 3000 times at room temperature, and the capacity retention rate was 92%. .

Example 11

Example 5 was repeated, except that the aqueous electrolyte was changed to lithium bisfluorosulfonimide, the electrolyte concentration was 10M, and other conditions remained unchanged, and the electrochemical stability window of the obtained aqueous electrolyte reached 3V.

The aqueous electrolyte was used in an aqueous lithium-ion battery according to the method of Example 1, and the charge-discharge test was carried out at 0.8-2.5V, the current density was 1A/g, and it was cycled 3000 times at room temperature, and the capacity retention rate was 91%. .

Example 12

Example 5 was repeated, except that the oxidant in the oligomer solute was changed to 0.0005M (NH ₄ ) ₂ S ₂ O ₈ , and other conditions remained unchanged, and the electrochemical stability window of the obtained aqueous electrolyte reached 3.2V.

The aqueous electrolyte was used in an aqueous lithium-ion battery according to the method of Example 1, and the charge-discharge test was carried out at 1.5-2.8V, the current density was 1A/g, and the cycle was 3000 times at room temperature, and the capacity retention rate was 92%. .

Example 13

Example 5 was repeated, with the difference that the weight ratio of the oligomer solute to water was 2:1, and other conditions remained unchanged, and the electrochemical stability window of the obtained aqueous electrolyte reached 3.2V.

The aqueous electrolyte was used in an aqueous lithium-ion battery according to the method of Example 1, and the charge-discharge test was carried out at 0.8-2.6V, the current density was 1A/g, and it was cycled 3000 times at room temperature, and the capacity retention rate was 93%. .

Example 14

The specific composition of the aqueous electrolyte in this example is a solvent oligomer solution, and the electrolyte is lithium bis-trifluoromethanesulfonimide. The preparation method is as follows: ₁ mL of aniline is added to 10 mL of FeCl aqueous solution with a concentration of 0.0005M, and after the reaction, 1 mL of aniline is added. The relatively clear supernatant is centrifuged, and the obtained clear oligomer solution is mixed with water, and the concentration of the oligomer in the solution is 10 ^-3 M, and the lithium bisfluorosulfonimide is dissolved in the aforementioned oligomer solution, An electrolyte solution with an electrolyte concentration of 21 M was prepared to obtain the aqueous electrolyte solution of this example. The electrochemical window of the aqueous electrolyte prepared in this example was tested by three-electrode linear voltammetry, and the electrochemical stability window of the aqueous electrolyte reached 3.0V.

The aqueous electrolyte of this example is used in an aqueous lithium-ion battery, the positive electrode is lithium manganate, the negative electrode is titanium dioxide, and the positive and negative electrodes are mixed according to the weight ratio of active material/carbon black/PVDF=8/1/1 to make a slurry , the positive electrode material is coated on the titanium foil, and the negative electrode material is coated on the carbon-coated aluminum foil, and is made into an electrode after drying. Then, a lithium-ion battery is assembled, the separator used is a glass fiber GFF separator, and the electrolyte is the aqueous electrolyte of this example. The charge-discharge test was carried out at 0.8-2.5V, the current density was 1A/g, and the capacity retention rate was 93% after 3000 cycles at room temperature.

Example 15

Example 3 was repeated, except that the pyrrole was replaced with aniline, and the remaining conditions remained unchanged, and the electrochemical stability window of the obtained aqueous electrolyte reached 3.1V.

The aqueous electrolyte was used in an aqueous lithium-ion battery according to the method of Example 1, and the charge-discharge test was carried out at 1.5-2.7V, the current density was 1A/g, and it was cycled 3000 times at room temperature, and the capacity retention rate was 92%. .

Example 16

Example 4 was repeated, with the difference that the pyrrole was replaced with aniline, and the remaining conditions remained unchanged, and the electrochemical stability window of the obtained aqueous electrolyte reached 3.1V.

The aqueous electrolyte was used in an aqueous lithium-ion battery according to the method of Example 1, and the charge-discharge test was carried out at 0.5-2.0V, the current density was 1A/g, the cycle was 4000 times at room temperature, and the capacity retention rate was 95.5%. .

Example 17

Example 1 was repeated, except that the pyrrole was replaced with thiophene, and the other conditions remained unchanged, and the electrochemical stability window of the obtained aqueous electrolyte reached 3.0V.

The aqueous electrolyte was used in an aqueous lithium-ion battery according to the method of Example 1, and the charge-discharge test was carried out at 0.7-2.6V, the current density was 1A/g, and it was cycled 3000 times at room temperature, and the capacity retention rate was 92%. .

Example 18

Example 3 was repeated, except that the pyrrole was replaced with thiophene, and the other conditions remained unchanged, and the electrochemical stability window of the obtained aqueous electrolyte reached 3.1V.

The aqueous electrolyte was used in an aqueous lithium-ion battery according to the method of Example 1, and the charge-discharge test was carried out at 1.5-2.6V, the current density was 1A/g, and the capacity retention rate was 92% at room temperature for 3000 cycles. .

Example 19

Example 4 was repeated, except that the pyrrole was replaced with thiophene, the other conditions remained unchanged, and the electrochemical stability window of the obtained aqueous electrolyte reached 3.0V.

The aqueous electrolyte was used in an aqueous lithium-ion battery according to the method of Example 1, and the charge-discharge test was carried out at 0.4-2.1V, the current density was 1A/g, and it was cycled 4000 times at room temperature, and the capacity retention rate was 93%. .

Comparative Example 1

Example 17 was repeated, except that the obtained "thiophene oligomer" was replaced by "diethyl sulfate", and other conditions remained unchanged to prepare an aqueous electrolyte with an electrochemical stability window of 2.5V.

The aqueous electrolyte was used in an aqueous lithium-ion battery according to the method of Example 1, and the charge-discharge test was carried out at 0.7-2.6V, the current density was 1A/g, the cycle was 3000 times at room temperature, and the capacity retention rate was 15%. .

Obviously, the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, rather than limiting the embodiments of the present invention. Changes or changes in other different forms cannot be exhausted here, and all obvious changes or changes derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims (10)

1. an oligomer-based aqueous lithium-ion battery electrolyte, characterized in that, comprising oligomer solute, electrolyte and water; wherein, The oligomer solute is selected from oligomers of pyrrole, aniline or thiophene; The electrolyte is a lithium-containing soluble salt. 2. The electrolyte according to claim 1, wherein the degree of polymerization of the oligomer solute is 2-10; Preferably, the oligomer solute is obtained by adding pyrrole, aniline or thiophene monomer to an aqueous solution containing an oxidant, and after the reaction, centrifuging the supernatant; Preferably, the oxidant is selected from one or more of ferric chloride and ammonium persulfate; Preferably, in the aqueous solution of the oxidant, the concentration of the oxidant is 0.0005-0.005M. 3. The electrolyte according to claim 1, wherein the concentration of the electrolyte in the electrolyte is 1-21M. 4 . The electrolyte according to claim 1 , wherein the concentration of the oligomer solute is 10 ⁻⁶ to 1M. 5 . 5. The electrolyte according to claim 1, wherein the lithium-containing soluble salt is selected from the group consisting of lithium sulfate, lithium nitrate, lithium acetate, lithium bistrifluoromethanesulfonimide and bisfluorosulfonimide A type of lithium. 6. The application of the electrolyte according to any one of claims 1-5 in electrochemical energy storage devices. 7. An electrochemical energy storage device, characterized in that, comprising the electrolyte according to any one of claims 1-5. 8 . The electrochemical energy storage device according to claim 7 , wherein the electrochemical energy storage device is an aqueous secondary battery or an aqueous electrochemical supercapacitor or an organic combination of the two. 9 . 9 . The electrochemical energy storage device according to claim 8 , wherein the aqueous secondary battery is selected from aqueous lithium-ion batteries. 10 . 10. The electrochemical energy storage device according to claim 9, wherein the aqueous lithium-ion battery comprises a positive electrode and a negative electrode; wherein, the positive electrode material is selected from lithium manganate, lithium iron phosphate or ternary material NCM523; The negative electrode material is selected from titanium dioxide or lithium titanate.

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