Aqueous zinc ion battery electrolyte additive in low temperature range and application thereof

Abstract

The application discloses acetyl urea used as an electrolyte additive of a water-based zinc ion battery in a low-temperature domain. Due to the direct connection of carbonyl and amino groups in acetyl urea, the binding energy of the O atom in the carbonyl and zinc ions is large, which can replace part of the water molecules in the solvent sheath structure of zinc ions, and reduce the number of water molecules in the solvent sheath structure of zinc ions; at the same time, a solid electrolyte interface layer SEI is generated in situ on the surface of the zinc negative electrode tip, the SEI layer inhibits the continuous growth of the zinc tip into zinc dendrites, and prevents the contact of water molecules with the surface of the Zn negative electrode, thereby effectively inhibiting the hydrogen evolution reaction and corrosion reaction on the zinc surface, so as to adapt to the charging and discharging process under low-temperature conditions. The application solves the problems of dendrites, hydrogen evolution and corrosion of the negative electrode of the current water-based zinc ion battery by a safe and low-cost method, and obtains a high-performance water-based zinc battery, which can help the development of zinc batteries with low cost and high performance, and greatly promotes the commercial application process of the water-based zinc battery.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of battery electrolyte, and particularly relates to a water-based zinc ion battery low-temperature domain electrolyte additive and application thereof. BACKGROUND

[0002] Lithium ion batteries have the advantages of high energy density, long cycle life and low self-discharge rate, are the mainstream secondary batteries in today's society, and play an important role in the fields of electronic devices, energy, etc. However, the lithium ion battery has the defects of high manufacturing cost and low safety, while the emerging water-based zinc ion battery has the characteristics of high energy density, low cost and safety and environmental protection, and has attracted much attention from researchers.

[0003] However, since the water-based zinc ion battery electrolyte contains a large amount of water, a series of problems are caused, such as positive electrode dissolution, negative electrode corrosion, passivation and hydrogen evolution reaction, etc. The electrolyte, as the "blood" of the battery, plays an irreplaceable role in the efficient cycle of the battery. Therefore, the introduction of an electrolyte additive is a very simple and efficient strategy. The existing electrolyte uses additives (such as dimethyl sulfoxide and sodium dodecyl sulfate) which are toxic and high in cost, completely deviating from the advantages of safety and low cost of the water-based zinc battery. SUMMARY

[0004] The technical problem to be solved by the present application is to provide an economical, safe and efficient water-based zinc ion battery low-temperature domain electrolyte additive and application thereof.

[0005] In order to solve the above technical problems, the present application adopts the following technical solutions:

[0006] Acetyl urea (C3H6N2O2, abbreviated as ACE) is used as a water-based zinc ion battery low-temperature domain electrolyte additive.

[0007] The water-based zinc ion battery low-temperature domain electrolyte comprises a soluble zinc salt and the above-mentioned additive.

[0008] The concentration of the soluble zinc salt is 1-4 mol / L, and the concentration of the additive is 0.01-0.05 mol / L.

[0009] The concentration of the soluble zinc salt is 2-4 mol / L, and the concentration of the additive is 0.01-0.02 mol / L.

[0010] The soluble zinc salt is one or a combination of zinc sulfate, zinc chloride, zinc bromide, zinc nitrate, zinc acetate and trifluoromethane sulfonic acid zinc.

[0011] The above-mentioned electrolyte additive or electrolyte is applied in the preparation of a water-based zinc ion battery.

[0012] The water-based zinc ion battery comprises a positive electrode, a negative electrode, a separator and the above-mentioned electrolyte.

[0013] The positive electrode is a manganese-based oxide, a vanadium-based oxide, or a Prussian blue analogue.

[0014] The negative electrode is zinc or a zinc alloy.

[0015] The separator is glass fiber, qualitative filter paper, or polypropylene fiber separator.

[0016] In view of the problems existing in the current aqueous zinc ion battery, the inventors have found that acetyl urea can be used as an electrolyte additive for the aqueous zinc ion battery in a low temperature range. Due to the direct connection of carbonyl and amino groups in acetyl urea, the O atom in the carbonyl group can combine with zinc ions with large binding energy, replace part of the water molecules in the zinc ion solvation sheath structure, and reduce the number of water molecules in the zinc ion solvation sheath structure. At the same time, a solid electrolyte interface layer (SEI) is generated in situ on the surface of the zinc negative electrode tip. The SEI layer inhibits the continuous growth of the zinc tip into zinc dendrites, and prevents water molecules from contacting the surface of the Zn negative electrode, effectively inhibiting the hydrogen evolution reaction and corrosion reaction on the surface of the zinc, so as to adapt to the charging and discharging process under low temperature conditions. Therefore, the aqueous zinc ion battery formed by using the electrolyte provided by the present application exhibits high cycle stability. Moreover, the additive amount of the additive of the present application is extremely small, the electrolyte is easy to prepare, and has the characteristics of low cost and strong repeatability. In summary, the present application solves the problems of dendrites, hydrogen evolution, corrosion and the like existing in the negative electrode of the current aqueous zinc ion battery by a safe and low-cost method, and obtains a high-performance aqueous zinc battery, which can help the development of zinc batteries with low cost and high performance, and greatly promote the commercial application process of aqueous zinc batteries. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a graph of the electrochemical polarization curve measurement results of Example 1 and Comparative Example 1.

[0018] Figure 2 is a scanning electron microscope characterization result graph of zinc electrodeposition, in which: (a) is a scanning electron microscope characterization of the Zn anode of Example 2 after deposition at 5 mA cm -2 after the next cycle, and (b) is a scanning electron microscope characterization of Comparative Example 2.

[0019] Figure 3 is an X-ray diffraction characterization result graph of the cycled zinc anode using Example 2 and Comparative Example 2.

[0020] Figure 4 is a long cycle performance test graph of the Zn||Zn symmetric cell of the aqueous zinc ion battery using the electrolyte of Example 3 and the reference electrolyte of Comparative Example 3.

[0021] Figure 5 is a low-temperature long cycle performance test graph of the Zn||Zn symmetric cell of the aqueous zinc ion battery using the electrolyte of Example 4 and the reference electrolyte of Comparative Example 4.

[0022] Figure 6 This is a graph showing the long-cycle performance of an aqueous zinc-ion battery (Zn||V2O5) using the electrolyte tested in Example 5 and the reference electrolyte in Comparative Example 5. Detailed Implementation

[0023] Example 1

[0024] Acetourea (ACE) was used as an additive in the electrolyte of an aqueous zinc-ion battery to prepare a composite electrolyte with 2 mol / L zinc sulfate solution (ZS) for zinc electrodeposition, verifying the effect of acetourea on inducing uniform zinc ion deposition. The specific operation was as follows:

[0025] At room temperature, 14.378 g of zinc sulfate heptahydrate and 0.051 g of acetylurea were added to 25 ml of deionized water and sonicated for 20 min to disperse them completely, thus preparing an electrolyte solution containing 2 mol / L zinc sulfate and 0.02 mol / L acetylurea in 25 ml.

[0026] Comparative Example 1

[0027] At room temperature, 14.378 g of zinc sulfate heptahydrate was added to 25 ml of deionized water and sonicated for 20 min to completely disperse it, thus preparing an electrolyte solution containing 2 mol / L zinc sulfate in 25 ml.

[0028] Electrokinetic polarization curves were measured using the electrolytes of Example 1 and Comparative Example 1 with a three-electrode method. The test results are as follows: Figure 1 As shown, the corrosion current in Example 1 decreased significantly, reducing the damage of the aqueous electrolyte to the zinc anode; the corrosion current in the comparative example was significant, indicating that the corrosion of the zinc sheet was aggravated, and the aqueous electrolyte caused obvious damage to the zinc anode.

[0029] Example 2

[0030] Acetourea was used as an additive in the electrolyte of an aqueous zinc-ion battery to prepare a composite electrolyte with a 2 mol / L zinc sulfate solution for zinc electrodeposition, verifying the effect of acetourea on inducing uniform zinc ion deposition. The specific operation was as follows:

[0031] At room temperature, 14.378 g of zinc sulfate heptahydrate and 0.051 g of acetylurea were added to 25 ml of deionized water and sonicated for 20 min to disperse them completely, thus preparing an electrolyte solution containing 2 mol / L zinc sulfate and 0.02 mol / L acetylurea (ACE) in 25 ml.

[0032] Comparative Example 2

[0033] At room temperature, 14.378 g of zinc sulfate heptahydrate was added to 25 ml of deionized water and sonicated for 20 min to completely disperse it, thus preparing an electrolyte solution containing 2 mol / L zinc sulfate in 25 ml.

[0034] The scanning electron microscope of zinc electrodeposition and the X-ray diffraction of the cycled zinc anode were tested using the electrolyte of Example 2 and Comparative Example 2, and the test results are shown in Figure 2 and Figure 3 :

[0035] Figure 2 The deposition morphology of the assembled symmetric battery after cycling at a current density of 5 mA cm -2 , Example 2, due to the presence of the SEI protective layer formed, zinc ions are deposited in a layered stacking morphology parallel to the basal plane, with no obvious dendrites; the zinc deposition structure of Comparative Example 2 is loose, with many chaotic clusters and corrosion pits, which can exacerbate the corrosion reaction and the accumulation of by-products, ultimately leading to battery failure.

[0036] Figure 3 The X-ray diffraction characterization of zinc deposition is shown, it can be seen that all the characteristic peaks of Example 2 match well with the standard phase of metallic zinc (PDF #65-3358), and the Zn(002) peak has the highest intensity, indicating that the main crystal plane of zinc ion deposition is the Zn(002) crystal plane parallel to the basal plane, and no by-product peak is observed. All the characteristic peaks of Comparative Example 2 match well with the standard phase of metallic zinc (PDF #78-0246), and the Zn(101) peak has the highest intensity, indicating that the main crystal plane of zinc ion deposition is the Zn(101) crystal plane perpendicular to the basal plane, and the formation of by-product Zn4SO4OH6·5(H2O) is observed.

[0037] Example 3

[0038] An acetyl urea was used as an additive for aqueous zinc ion battery electrolyte to prepare Zn||Zn symmetric battery, and the effect of the additive on the service life of zinc electrode was verified. The specific operation is as follows:

[0039] At room temperature, 14.378 g of zinc sulfate heptahydrate was added to 25 ml of deionized water and ultrasonicated for 20 min to make it completely dispersed, and an electrolyte containing 2 mol / L zinc sulfate and 0.02 mol / L acetyl urea was prepared; zinc foil was used as the positive and negative electrode, glass fiber was used as the separator, and 120 μL of the above obtained electrolyte was taken to assemble a CR2032 type button symmetric battery.

[0040] Comparative Example 3

[0041] At room temperature, 11.5 g of zinc sulfate heptahydrate was added to 5 ml of deionized water and ultrasonicated for 20 min to make it completely dispersed, and an electrolyte containing 2 mol / L zinc sulfate was prepared. Zinc foil was used as the positive and negative electrode, glass fiber was used as the separator, and 120 μL of the above obtained electrolyte was taken to assemble a CR2032 type button symmetric battery.

[0042] The batteries from Example 3 and Comparative Example 3 were used to conduct cyclic charge-discharge tests on the Newway battery testing system. The current density was 5 mA·cm⁻¹. -2 The surface capacity is 2.5mAh·cm³. -2 .

[0043] Test results are as follows Figure 4 As shown, Example 3, using acetourea electrolyte additive, operated for 600 hours, while Comparative Example 3 experienced a short circuit after 50 hours of cycling. The significantly increased operating time in Example 3 was attributed to the SEI layer formed by acetourea on the zinc anode surface, which suppressed side reactions, improved zinc deposition / stripping reaction kinetics, and consequently inhibited zinc dendrite growth.

[0044] Example 4

[0045] Azoxylurea was used as an additive in the electrolyte of an aqueous zinc-ion battery to prepare a Zn||Zn symmetric cell, and the effect of the additive on improving the service life of the zinc electrode under low-temperature conditions was verified. The specific operation was as follows:

[0046] At room temperature, 14.378 g of zinc sulfate heptahydrate was added to 25 ml of deionized water and sonicated for 20 min to disperse it completely, thus preparing an electrolyte containing 2 mol / L zinc sulfate and 0.02 mol / L acetylurea in 25 ml. Using zinc foil as the positive and negative electrodes and glass fiber as the separator, 120 μL of the electrolyte obtained above was used to assemble a CR2032 coin cell.

[0047] Comparative Example 4

[0048] At room temperature, 11.5 g of zinc sulfate heptahydrate was added to 5 ml of deionized water and sonicated for 20 min to ensure complete dispersion, thus preparing 25 ml of electrolyte containing 2 mol / L zinc sulfate. Using zinc foil as the positive and negative electrodes and glass fiber as the separator, 120 μL of the above electrolyte was used to assemble a CR2032 coin cell.

[0049] The batteries from Example 4 and Comparative Example 4 were used to conduct cyclic charge-discharge tests on the Newway battery testing system. The operating temperature was set to -10°C, and the current density was 0.25 mA·cm⁻¹. -2 The surface capacity is 0.25 mAh·cm³. -2 .

[0050] Test results are as follows Figure 5 As shown, the working time of Example 4 using acetourea electrolyte additive was 1800 h, while that of Comparative Example 4 was 99 h. The significant increase in working time is due to the fact that acetourea can capture free water molecules and form hydrogen bonds, inhibiting the activity of water. In addition, the SEI layer induced on the zinc anode surface can also greatly protect the zinc anode and improve the zinc deposition / stripping reaction kinetics, thereby inhibiting the growth of zinc dendrites.

[0051] Example 5

[0052] Aqueous urea was used as an electrolyte additive in aqueous zinc-ion batteries to prepare them. The effect of acetylurea electrolyte additive on improving the capacity retention and lifespan of the aqueous zinc-ion batteries was tested. The specific operation was as follows:

[0053] At room temperature, 14.378 g of zinc sulfate heptahydrate and 0.051 g of acetylurea were added to 25 ml of deionized water and sonicated for 20 min to ensure complete dispersion, thus preparing 25 ml of electrolyte containing 2 mol / L zinc sulfate and 0.02 mol / L acetylurea. The V2O5 cathode preparation process was as follows: Vanadium oxide (V2O5, Macklin, 99%, 0.3 g) was dissolved in 10 mL of 2M sodium chloride (NaCl) aqueous solution and stirred continuously for 72 h. The resulting orange-red gel was washed several times with deionized water and ethanol. Then, it was dried in a vacuum oven at 80 °C for 12 h. After cooling, the solution was filtered, dried, and ground for later use. 80 mg of the above-prepared V2O5 was mixed with SuperP and polyvinylidene fluoride at a mass ratio of 7:2:1, ground in an agate mortar for 30 min, and N-methylpyrrolidone was added. After stirring for 12 h, the mixture was evenly coated onto the surface of titanium foil with a spatula. After complete drying, it was sliced ​​for later use.

[0054] Using the V2O5 positive electrode material prepared above as the positive electrode, zinc foil as the negative electrode, and glass fiber as the separator, 120 μL of the above electrolyte was used to assemble a CR2032 type aqueous zinc-ion button cell.

[0055] Comparative Example 5

[0056] At room temperature, 14.378 g of zinc sulfate heptahydrate was added to 25 ml of deionized water and sonicated for 20 min to completely disperse it, preparing 25 ml of electrolyte containing 2 mol / L zinc sulfate. 120 μL of this electrolyte was used as the positive electrode material (V₂O₅) prepared in the same manner as in Example 5, with zinc foil as the negative electrode and glass fiber as the separator, to assemble a CR2032 type aqueous zinc-ion coin cell.

[0057] Using the batteries from Example 5 and Comparative Example 5, cyclic charge-discharge tests were conducted on the Newway battery testing system at a current density of 1 A g. -1 .

[0058] Test results are as follows Figure 6 As shown, Example 5 uses a zinc sheet (100 μm) at 1 Ag. -1The discharge specific capacity under the condition of 0.2 C, 1.0 M ZnSO4, 0.5 M Na2SO4, 0.5 M NaCl, 0.5 M NaHCO3, 0.5 M Na2CO3, 0.5 M Na2SO3, 0.5 M Na2S2O3, 0.5 M Na2S2O4, 0.5 M Na2S, 0.5 M Na2S2O5, 0.5 M Na2S2O6, 0.5 M Na2S2O7, 0.5 M Na2S2O8, 0.5 M Na2S2O9, 0.5 M Na2S3O2, 0.5 M Na2S3O3, 0.5 M Na2S

Claims

1. A low-temperature range electrolyte for aqueous zinc-ion batteries, characterized by The electrolyte comprises a soluble zinc salt and acetyl urea, the concentration of the soluble zinc salt is 1-4 mol / L, and the concentration of the acetyl urea is 0.01-0.05 mol / L.

2. The electrolyte according to claim 1, characterized in that The concentration of the soluble zinc salt is 2-4 mol / L, and the concentration of the acetyl urea is 0.01-0.02 mol / L.

3. The electrolyte of claim 2, wherein The soluble zinc salt is one of zinc sulfate, zinc chloride, zinc bromide, zinc nitrate, zinc acetate and zinc trifluoromethane sulfonate or a combination thereof.

4. Use of the electrolyte in claim 1 in the preparation of a water-based zinc ion battery.

5. An aqueous zinc-ion battery, characterized in that The electrolyte comprises a positive electrode, a negative electrode, a separator and the electrolyte in claim 1.

6. The aqueous zinc-ion battery of claim 5, wherein The positive electrode is a manganese-based oxide, a vanadium-based oxide or a Prussian blue analogue.

7. The aqueous zinc-ion battery of claim 6, wherein The negative electrode is zinc or a zinc alloy.

8. The aqueous zinc-ion battery of claim 7, wherein The separator is a glass fiber, a qualitative filter paper or a polypropylene fiber separator.

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