Aqueous zinc ion battery and electrolyte thereof

Abstract

The application belongs to the field of aqueous zinc ion batteries, and particularly relates to an electrolyte of an aqueous zinc ion battery, which is an aqueous solution containing a zinc salt and an additive, wherein the additive comprises NaCl, NaF, NaBr and NaI. The application also includes the application of the electrolyte. The sodium-type quaternary anion additive can effectively stabilize the hydrogen bond network of water to inhibit the activity of water, and can deeply optimize the super-low temperature performance. In addition, the sodium-type quaternary anion additive can effectively inhibit gas production at high temperature, and improve the high-temperature performance. The electrolyte can significantly improve the super-wide temperature range performance and long cycle performance of the aqueous zinc ion battery.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of zinc ion batteries, and particularly relates to the electrolyte of zinc ion batteries. BACKGROUND

[0002] The aqueous zinc ion battery contains an aqueous solution, and a common electrolyte is a zinc salt aqueous solution, wherein the zinc salt mainly includes zinc chloride, zinc sulfate, Zn(CF3SO3)2, Zn(CH3F3SO3)2, Zn(CH3COO)2, etc., and the concentration of the zinc salt is generally 0.5-5M. However, the performance of the conventional electrolyte is not ideal. In view of this problem, the mainstream idea in the industry is to add various additives to the electrolyte, aiming to improve different performances thereof.

[0003] For example, the Chinese patent document with the publication number CN112510178A discloses a seawater-based electrolyte, which is an aqueous solvent dissolving a zinc salt and an additive, wherein the additive is one or a mixture of several of MnSO4, Mn(CF3SO3)2, MgCl2, MgSO4, NaCl, and Na2SO4; and the molar ratio of the additive to the zinc salt is 2:1-1:10. Again, the Chinese patent document with the publication number CN114824263A discloses a Zn@Zn-E composite negative electrode, its preparation and application in an aqueous zinc ion battery, and specifically discloses an aqueous solution electrolyte dissolving a zinc salt, a compound containing a non-metallic element E, a complexing agent, a conductive salt, a grain refiner, and an anode activator.

[0004] In summary, although there are many reports on electrolytes modified by various additives in the prior art, and some of the additive schemes claim to improve the low-temperature performance, most of them can only improve the low-temperature performance at-10℃, and it is difficult to further improve the performance at ultra-low temperature (such as-40℃). In addition, the aqueous electrolyte is prone to gas generation at high temperature, especially at high temperature above 60℃, and the high-temperature performance is not ideal, making it difficult to meet the application requirements of low temperature and high temperature. That is, the existing aqueous zinc ion battery is still difficult to adapt to the application requirements of ultra-wide temperature range and long cycle. SUMMARY

[0005] In view of the problems faced by the aqueous zinc ion battery, the first object of the present application is to provide an electrolyte for an aqueous zinc ion battery, aiming to improve the low-temperature, high-temperature, and long-cycle stability thereof.

[0006] The second object of the present application is to provide an aqueous zinc ion battery comprising the electrolyte.

[0007] An electrolyte for an aqueous zinc ion battery is an aqueous solution dissolving a zinc salt and an additive, wherein the additive includes NaCl, NaF, NaBr, and NaI.

[0008] The sodium type quaternary anion additive combination of the application can effectively stabilize the hydrogen bond network of water to inhibit the activity of water, can deeply optimize the super low temperature performance, and can effectively inhibit high temperature gas production and improve high temperature performance.

[0009] In the application, the zinc salt can be a water-soluble zinc salt known in the industry, for example, one or more of zinc sulfate, zinc trifluoromethane sulfonate, bis-trifluoromethane sulfonyl zinc Zn(TFSI)2, zinc acetate Zn(CH3COO)2.

[0010] In the application, the concentration of the zinc salt is 0.5-2 M, preferably 0.5-1 M, and further 0.7-0.9 M. In order to reduce the activity of water, the prior art mostly needs to rely on high zinc ion concentration to achieve, however, the research of the application shows that the combination of the additive composition can unexpectedly improve the super wide temperature range performance and long cycle performance of the prepared electrolyte under low zinc ion concentration.

[0011] The research of the application also shows that the combined control of the composition ratio of the additive helps to further adjust the activity of water, and helps to further improve the super wide temperature range performance and long cycle performance of the water-based zinc ion battery.

[0012] In the application, the molar ratio of NaF, NaCl, NaBr and NaI in the additive is 0.05-0.15:0.05-0.15:0.02-0.06:0.02-0.06; preferably 0.08-0.12:0.07-0.09:0.04-0.05:0.03-0.05; and more preferably 0.9-0.1:0.07-0.08:0.045-0.05:0.04-0.045. Research shows that the preferred ratio can obtain better component synergy, and can obtain better super wide temperature amplitude stability and stability.

[0013] In the application, the molar amount of NaF in the additive is preferably 33-38%, the molar amount of NaCl is preferably 30-32%, the molar amount of NaBr is 15-20%, and the balance is NaI.

[0014] Preferably, the total concentration of the additive is 20-55% of the molar amount of the zinc salt anion, preferably 20-40%, and further preferably 30-35%. Research shows that the preferred additive ratio can obtain better component synergy, and can obtain better super wide temperature amplitude stability and stability.

[0015] The application further provides a water-based zinc ion battery, comprising an electric core composed of a positive electrode, a diaphragm and a negative electrode in sequence, and an electrolyte for soaking the electric core, wherein the electrolyte is the electrolyte provided by the application.

[0016] The water-washed zinc ion battery provided by the application can comprise other components such as the positive electrode, the negative electrode and the diaphragm known in the industry, or can be obtained by adjusting the known means.

[0017] The positive electrode comprises a current collector and a positive electrode material compounded on the surface of the current collector, and the active material in the positive electrode material can comprise at least one of manganese dioxide, vanadium pentoxide, ammonium vanadate, sodium vanadate phosphate and sodium iron pyrophosphate.

[0018] The negative electrode can be zinc metal.

[0019] The diaphragm can be a cellulose diaphragm with a thickness of 20-600 microns.

[0020] Beneficial effects

[0021] The sodium-type quaternary anion additive provided by the application can effectively inhibit the activity of water and promote the uniform and rapid migration of zinc ions by forming a stable hydrogen bond network, can deeply optimize the ultralow-temperature performance, and can effectively inhibit the gas production at high temperature and improve the high-temperature performance, and the electrolyte provided by the application can significantly improve the ultrawide-temperature-range performance and long cycle performance of the water-based zinc ion battery.

[0022] The researches of the application show that the electrolyte can be applied at a low temperature of-40 DEG C and a high temperature of 80 DEG C, can meet the application requirements in an ultrawide temperature range, and can also have excellent long cycle stability. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The electrochemical performance of the symmetric batteries of Example 1 and Comparative Example 1 at 25 DEG C, 5mA / cm 2 and 5mAh / cm 2 ;

[0024] Figure 2 The electrochemical performance of the symmetric batteries of Example 1 and Comparative Example 1 at-40 DEG C, 1mA / cm 2 and 1mAh / cm 2 ;

[0025] Figure 3 The electrochemical performance of the symmetric batteries of Example 1 and Comparative Example 1 at 80 DEG C, 1mA / cm 2 and 1mAh / cm 2 ;

[0026] Figure 4 Electrochemical performance of the full cell for Example 1 and Comparative Example 1 at 25°C. DETAILED DESCRIPTION

[0027] Example 1

[0028] The electrolyte is an aqueous solution containing zinc sulfate and an additive, wherein the concentration of zinc sulfate is 0.8M;

[0029] The additive is NaF, NaCl, NaBr and Nal, and the concentrations thereof are 0.096M, 0.08M, 0.048M and 0.04M, respectively.

[0030] Test:

[0031] (1): Half cell:

[0032] The zinc sheet is assembled into a symmetrical cell with the electrolyte, and the cycle life thereof is 2500h at 25°C, 5mA / cm2and 5mAh / cm2, 1000h at -40°C, 1mA / cm2and 1mAh / cm2, and 2000h at 80°C, 1mA / cm2and 1mAh / cm2.

[0033] (2): Full cell:

[0034] Positive electrode: V2O5, conductive agent (conductive carbon black), and binder PVDF are compounded on a current collector at a weight ratio of 7:2:1 to form a positive electrode, and the positive electrode, a separator, a zinc negative electrode, and the above electrolyte are compounded to form a water-based zinc ion battery.

[0035] Cycled for 910 cycles (referring to the cycle number when the capacity decays to 40%) at a current density of 1A / g and a temperature of 25°C.

[0036] Example 2

[0037] Compared with Example 1, the only difference is that the concentration of zinc sulfate in the electrolyte is 0.5M, and the other operations, parameters and tests are the same as those of Example 1.

[0038] Symmetrical cell performance: the cycle life thereof is 2331h at 25°C, 5mA / cm2and 5mAh / cm2, 810h at -40°C, 1mA / cm2and 1mAh / cm2, and 1612h at 80°C, 1mA / cm2and 1mAh / cm2.

[0039] Full cell performance: cycled for 821 cycles at a temperature of 25°C.

[0040] Example 3

[0041] Compared with Example 1, the only difference is that the concentration of zinc sulfate in the electrolyte is 1.5M, and other operations, parameters and tests are the same as those in Example 1.

[0042] Symmetric battery performance: the cycle life thereof is 1922h at 25℃, 5mA / cm2 and 5mAh / cm2, 631h at-40℃, 1mA / cm2 and 1mAh / cm2, and 1485h at 80℃, 1mA / cm2 and 1mAh / cm2.

[0043] Full battery performance: the full battery life is 740 weeks.

[0044] It can be seen from Examples 1-3 that, by using the additive described in the application, the zinc salt concentration is controlled to be below 1M, in particular, controlled to be 0.7-0.9M, which is helpful to obtain better super-low temperature and super-high temperature performance, and also can obtain better long cycle stability.

[0045] Example 4

[0046] Compared with Example 1, the only difference is that zinc triflate is used as the zinc salt, and other operations, parameters and tests are the same as those in Example 1.

[0047] Symmetric battery performance: the cycle life thereof is 2430h at 25℃, 5mA / cm2 and 5mAh / cm2, 923h at-40℃, 1mA / cm2 and 1mAh / cm2, and 1705h at 80℃, 1mA / cm2 and 1mAh / cm2.

[0048] Full battery performance: the full battery life of the full battery assembled with V2O5 and zinc sheet is 850 weeks.

[0049] Example 5

[0050] Compared with Example 1, the only difference is that the molar concentrations of the additives NaF, NaCl, NaBr and Nal in the electrolyte are 0.08M, 0.07M, 0.04M and 0.04M, respectively.

[0051] Symmetric battery performance: the zinc sheet is assembled into a symmetric battery with the electrolyte, and the cycle life thereof is 2213h at 25℃, 5mA / cm2 and 5mAh / cm2, 675h at-40℃, 1mA / cm2 and 1mAh / cm2, and 1560h at 80℃, 1mA / cm2 and 1mAh / cm2.

[0052] Full battery performance: the full battery life is 671 weeks.

[0053] Example 6

[0054] The difference compared with Example 1 is only that the molar ratio of the additives is changed, specifically: NaCl, NaF, NaBr and Nal, the concentrations of which are 0.096M, 0.08M, 0.048M and 0.04M respectively. And the total molar amount of the additives is the same as Example 1.

[0055] (1): Half-cell:

[0056] The cycle life is 2426h at 25℃, 5mA / cm2and 5mAh / cm2, 932h at -40℃, 1mA / cm2and 1mAh / cm2, and 1854h at 80℃, 1mA / cm2and 1mAh / cm2.

[0057] (2): Full-cell:

[0058] Cycled for 812 cycles at 1A / g current density and 25℃ temperature.

[0059] Comparative Example 1

[0060] The difference compared with Example 1 is only that the electrolyte is 0.8M zinc sulfate solution without additives, and other operations, operations and tests are the same as Example 1.

[0061] Symmetric cell performance: the cycle life is 110h at 25℃, 5mA / cm2and 5mAh / cm2, 95h at -40℃, 1mA / cm2and 1mAh / cm2, and initially decomposes at 80℃, 1mA / cm2and 1mAh / cm2, and then fails after 50h of cycling.

[0062] Full-cell performance: the full-cell fails after 200 cycles.

[0063] Comparative Example 2

[0064] The difference compared with Example 1 is only that the additive contains only sodium chloride, and the total concentration of the additive and other operations are the same as Example 1.

[0065] Symmetric cell performance: the cycle life is 1203h at 25℃, 5mA / cm2and 5mAh / cm2, 350h at -40℃, 1mA / cm2and 1mAh / cm2, and 965h at 80℃, 1mA / cm2and 1mAh / cm2.

[0066] Full-cell performance: the full-cell cycles for 482 cycles.

[0067] Comparative Example 3:

[0068] The difference between the comparative example and Example 1 is that the additive contains only sodium chloride and sodium fluoride (in the same molar ratio as in Example 1), the total concentration of the additive, and other operations are the same as in Example 1.

[0069] Symmetric cell performance: the cycle life thereof is 1380 h at 25°C, 5 mA / cm2and 5 mAh / cm2, 442 h at -40°C, 1 mA / cm2and 1 mAh / cm2, and 1020 h at 80°C, 1 mA / cm2and 1 mAh / cm2.

[0070] Full cell performance: the full cell is cycled for 510 cycles.

[0071] Comparative Example 4:

[0072] The difference between the comparative example and Example 1 is that the additive contains only sodium chloride, sodium fluoride and sodium iodide (in the same molar ratio as in Example 1), the total concentration of the additive, and other operations are the same as in Example 1.

[0073] Symmetric cell performance: the cycle life thereof is 1575 h at 25°C, 5 mA / cm2and 5 mAh / cm2, 483 h at -40°C, 1 mA / cm2and 1 mAh / cm2, and 1162 h at 80°C, 1 mA / cm2and 1 mAh / cm2.

[0074] Full cell performance: the full cell is cycled for 581 cycles.

[0075] Comparative Example 5:

[0076] The difference between the comparative example and Example 1 is that the sodium element in the additive is replaced by Zn, the total concentration of the anions in the additive, and other operations are the same as in Example 1.

[0077] Symmetric cell performance: the cycle life thereof is 1720 h at 25°C, 5 mA / cm2and 5 mAh / cm2, 505 h at -40°C, 1 mA / cm2and 1 mAh / cm2, and 1284 h at 80°C, 1 mA / cm2and 1 mAh / cm2.

[0078] Full cell performance: the full cell is cycled for 613 cycles.

[0079] Comparative Example 6:

[0080] The difference between the comparative example and Example 1 is that the sodium element in the additive is replaced by Mg, the total concentration of the anions in the additive, and other operations are the same as in Example 1.

[0081] Symmetric cell performance: it has a cycle life of 1810 h at 25°C, 5 mA / cm2and 5 mAh / cm2, 512 h at -40°C, 1 mA / cm2and 1 mAh / cm2, and 1244 h at 80°C, 1 mA / cm2and 1 mAh / cm2.

[0082] Full cell performance: the full cell cycled for 635 cycles.

[0083] Comparative Example 7:

[0084] Compared with Example 1, the difference is that in the additive, the sodium element in the additive is replaced by ammonium ion, the total anion concentration of the additive and other operations are the same as Example 1.

[0085] Symmetric cell performance: it has a cycle life of 1870 h at 25°C, 5 mA / cm2and 5 mAh / cm2, 553 h at -40°C, 1 mA / cm2and 1 mAh / cm2, and 1345 h at 80°C, 1 mA / cm2and 1 mAh / cm2.

[0086] Full cell performance: the full cell cycled for 668 cycles.

Claims

1. An electrolyte for an aqueous zinc ion battery, which is an aqueous solution in which a zinc salt, an additive are dissolved, characterized by, The additive comprises NaCl, NaF, NaBr and NaI; The concentration of the zinc salt is 0.5-2 M; The total concentration of the additive is 20-55% of the molar amount of the zinc salt anion.

2. The aqueous zinc-ion battery electrolyte of claim 1, wherein, The zinc salt comprises one or more of zinc sulfate, zinc trifluoromethane sulfonate, bis-trifluoromethane sulfonyl zinc Zn(TFSI)2, zinc acetate Zn(CH3COO)2.

3. The aqueous zinc-ion battery electrolyte of claim 1 or 2, wherein, The concentration of the zinc salt is 0.5-1 M.

4. The aqueous zinc ion battery electrolyte of claim 3, wherein, The concentration of the zinc salt is 0.7-0.9 M.

5. The aqueous zinc ion battery electrolyte of claim 1, wherein, In the additive, the molar ratio of NaF, NaCl, NaBr and NaI is 0.05-0.15:0.05-0.15:0.02-0.06:0.02-0.

06.

6. The aqueous zinc ion battery electrolyte of claim 5, wherein, In the additive, the molar ratio of NaF, NaCl, NaBr and NaI is 0.08-0.12:0.07-0.09:0.04-0.05:0.03-0.

05.

7. The aqueous zinc ion battery electrolyte of claim 6, wherein, In the additive, the molar ratio of NaF, NaCl, NaBr and NaI is 0.9-0.1:0.07-0.08:0.045-0.05:0.04-0.

045.

8. The aqueous zinc ion battery electrolyte of claim 1, 5, 6, or 7, wherein, The total concentration of the additive is 20-40% of the molar amount of the zinc salt anion.

9. The aqueous zinc ion battery electrolyte of claim 8, wherein, The total concentration of the additive is 30-35% of the molar amount of the zinc salt anion.

10. An aqueous zinc-ion battery comprising an electric core compounded by a positive electrode, a separator and a negative electrode in sequence, and an electrolyte solution soaking the electric core, characterized in that, The electrolyte is the electrolyte of any one of claims 1-9.

11. The aqueous zinc ion battery of claim 10, wherein, The positive electrode comprises a current collector and a positive electrode material compounded on the surface of the current collector, and the active material in the positive electrode material comprises at least one of manganese dioxide, vanadium pentoxide, ammonium vanadate, vanadium sodium phosphate and sodium iron pyrophosphate.

12. The aqueous zinc ion battery of claim 10, wherein, The negative electrode is a zinc metal negative electrode.

13. The aqueous zinc ion battery of claim 10, wherein, The separator is a cellulose separator, and the thickness is 20-600 μm.

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