Zinc-air capacitor battery based on double-anode structure and preparation method thereof

Abstract

The invention discloses a zinc-air capacitor battery based on a double-anode structure and a preparation method thereof, the zinc-air capacitor battery comprises a zinc metal cathode, a neutral electrolyte, an air electrode and a capacitor electrode, and the air electrode and the capacitor electrode are anodes connected in parallel. According to the zinc-air capacitor battery, on the basis of a neutral zinc-air battery, a capacitor electrode is introduced into a system, and the high-energy characteristic of the zinc-air battery and the high-power characteristic of a super capacitor are combined in one device, so that the zinc-air capacitor battery is constructed. The introduction of the capacitor electrode reduces the overpotential of charging and discharging of the zinc-air battery, improves the power of the battery, and prolongs the service life of the battery.

Description

Technical Field

[0001] The invention relates to the field of zinc-air batteries and hybrid capacitors, and in particular to a zinc-air capacitor battery with a double positive electrode structure and a preparation method thereof. Background Art

[0002] At present, lithium-ion batteries are the most successful commercial electrochemical storage technology and are widely used in automobiles and various portable electronic devices. However, lithium-ion batteries have problems such as high cost, low energy density and poor safety, and cannot meet the growing demand for large-scale energy storage. Therefore, we urgently need to develop low-cost, high-energy-density and safe battery systems. Compared with lithium-ion batteries, zinc-air batteries use aqueous electrolytes, which can effectively avoid the risk of combustion caused by electrolyte leakage. In addition, the theoretical energy density of zinc-air batteries is as high as 1086Wh / kg, and the earth's zinc reserves are more abundant than lithium, easy to mine and inexpensive. Therefore, zinc-air batteries are considered to be a promising electrochemical energy storage technology that can supplement lithium-ion batteries.

[0003] Conventional rechargeable zinc-air batteries consist of a zinc metal anode, an electrolyte, and an air cathode loaded with oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalysts. Due to the fast reaction kinetics of ORR and OER in alkaline electrolytes, alkaline electrolytes are commonly used electrolytes for zinc-air batteries. However, severe side reactions and dendrite formation at the zinc anode in alkaline zinc-air batteries lead to low energy efficiency during charge and discharge cycles and rapid battery failure. In contrast, neutral electrolytes are more environmentally friendly and mild, and can give zinc-air batteries a better service life. However, neutral zinc-air batteries usually exhibit poor ORR and OER reaction kinetics, and the corresponding batteries have large charge and discharge overpotentials and poor rate performance.

[0004] Metal ion capacitors are electrochemical capacitors that are usually composed of a porous carbon positive electrode and a metal negative electrode. They work by using the charge generated by ions in the electrolyte to store charge between the electrodes. They are able to charge and discharge at high rates, providing high energy density. Due to the low cost of porous carbon and zinc metal, zinc ion capacitors are safe, high-power, and low-cost energy storage technologies. However, zinc ion capacitors have the disadvantage of low energy density, which limits their widespread application. Summary of the invention

[0005] In view of the above problems, the present invention constructs a zinc-air capacitor battery based on a dual positive electrode structure. The zinc-air capacitor battery is composed of a dual positive electrode structure consisting of a zinc metal negative electrode, a neutral electrolyte, a capacitor electrode and an air electrode. The introduction of the capacitor electrode into the positive electrode reduces the battery charge and discharge overpotential, so that the zinc-air capacitor battery has a higher power output and prolongs the battery life.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] In a first aspect, the present invention provides a zinc-air capacitor battery based on a dual positive electrode structure, comprising a zinc metal negative electrode, a neutral electrolyte, an air electrode and a capacitor electrode, wherein the air electrode and the capacitor electrode are positive electrodes connected in parallel.

[0008] Preferably, the negative electrode uses zinc metal as the active material; zinc sheets, zinc foils, zinc blocks and various materials composited with zinc metal can be used as the negative electrode of the zinc-air capacitor battery.

[0009] Preferably, the electrolyte is a zinc salt aqueous solution, the solute of the zinc salt aqueous solution is one or more of zinc sulfate, zinc chloride, zinc acetate, zinc trifluoromethanesulfonate and zinc bis(trifluoromethylsulfonyl)imide; the concentration of the zinc salt solution is 0.2 to 5 mol / L, preferably 0.5 to 2 mol / L.

[0010] Preferably, the air electrode is an electrode loaded with carbon material on the surface of the current collector, with a loading amount of 1 to 8 mg / cm 2 The capacitor electrode is an electrode loaded with carbon material on the surface of the current collector, and the loading amount is 1 to 20 mg / cm 2 .

[0011] Preferably, the carbon material is selected from at least one of conductive carbon black, porous carbon, activated carbon, carbon nanotubes, and activated carbon fibers.

[0012] Preferably, the current collector comprises one of nickel foam, carbon paper and stainless steel mesh.

[0013] In a second aspect, the present invention provides a method for preparing a zinc-air capacitor battery based on a dual positive electrode structure, comprising the following steps:

[0014] (1) Preparation of dual positive electrodes: dispersing carbon material and binder in a solvent, mixing to form a slurry, applying the slurry to a current collector, and drying to obtain an air electrode;

[0015] The carbon material, the binder and the conductive additive are dispersed in a solvent, mixed to form a slurry, the slurry is applied to a current collector, and dried to obtain a capacitor electrode;

[0016] (2) Assembly of zinc-air capacitor battery based on dual positive electrode structure: Assemble in the order of zinc sheet, air electrode, and capacitor electrode, and add electrolyte to obtain a dual positive electrode structure zinc-air capacitor battery.

[0017] Preferably, in the air electrode preparation process of step (1), the mass ratio of the carbon material to the binder is (8-10):1; further preferably, the mass ratio of the carbon material to the binder is 9:1.

[0018] Preferably, in the capacitor electrode preparation process of step (1), the mass ratio of the carbon material, the conductive additive and the binder is (15-20):(1.5-2.5):1; further preferably, the mass ratio of the carbon material, the conductive additive and the binder is 85:10:5.

[0019] Preferably, the current collector in step (1) comprises one of nickel foam, carbon paper and stainless steel mesh.

[0020] Preferably, the binder in step (1) comprises one or more of sodium carboxymethyl cellulose, polytetrafluoroethylene and polyvinylidene fluoride.

[0021] Preferably, the conductive additive in step (1) includes one or more of carbon black, acetylene black, Ketjen black, conductive graphite and carbon nanotubes.

[0022] Preferably, the dispersant in step (1) comprises one or more of water, ethanol and N-methylpyrrolidone.

[0023] In a third aspect, the present invention provides a use of a dual positive electrode structure in a zinc-air capacitor battery, wherein the dual positive electrode structure comprises an air electrode and a capacitor electrode connected in parallel.

[0024] Preferably, the air electrode is an electrode loaded with carbon material on the surface of the current collector, with a loading amount of 1 to 8 mg / cm 2 The capacitor electrode is an electrode loaded with carbon material on the surface of the current collector, and the loading amount is 1 to 20 mg / cm 2 .

[0025] Preferably, the carbon material is selected from at least one of conductive carbon black, porous carbon, activated carbon, carbon nanotubes, and activated carbon fibers.

[0026] Preferably, the current collector comprises one of nickel foam, carbon paper and stainless steel mesh.

[0027] Beneficial Effects

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The present invention discloses a zinc-air capacitor battery with a dual positive electrode structure based on a neutral electrolyte and a preparation method thereof. Based on a neutral zinc-air battery, the present invention introduces a capacitor electrode into the system, combines the high energy characteristics of the zinc-air battery and the high power characteristics of the supercapacitor in one device, and constructs a "zinc-air capacitor battery". The introduction of the capacitor electrode reduces the overpotential of the zinc-air battery during charge and discharge, increases the power of the battery, and extends the service life of the battery; at the same time, it provides a new idea for the development of new multifunctional electronic devices in the future. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 A schematic diagram of the structure of a dual-positive-electrode zinc-air capacitor battery according to the present invention;

[0032] Figure 2 The constant current charge and discharge curves of the dual positive electrode structure zinc-air capacitor battery of Example 1 at different current densities;

[0033] Figure 3 The constant current charge and discharge curves of the zinc-air battery of Example 1 at different current densities;

[0034] Figure 4 The volt-ampere characteristic curves of the zinc-air battery of Example 1 and the zinc-air capacitor battery with a dual positive electrode structure are compared;

[0035] Figure 5 The power density and energy density of the dual positive electrode structure zinc-air capacitor battery of Example 1 are compared with those of the neutral zinc-air battery and the zinc capacitor at different current densities;

[0036] Figure 6 The number of cycles of the dual positive electrode structure zinc-air capacitor battery under different currents of Example 1 (limited capacity 2 mAh / cm 2 );

[0037] Figure 7 This is a time-voltage diagram of a long-term cycle of a dual-positive-electrode structure zinc-air capacitor battery of Example 1;

[0038] Figure 8 This is a graph showing the change of voltage and output power over time when the dual positive electrode structure zinc-air capacitor battery of Example 1 is discharged alternately at 0.1 mA and 2 mA;

[0039] Fig. 9 The constant current charge and discharge curves of the dual positive electrode structure zinc-air capacitor battery of Example 2 at different current densities;

[0040] Fig.10 The constant current charge and discharge curves of the zinc-air battery of Example 2 at different current densities;

[0041] Fig.11 The constant current charge and discharge curves of the dual positive electrode structure zinc-air capacitor battery of Example 2 and the zinc-air battery at the same current density are compared. DETAILED DESCRIPTION

[0042] Hereinafter, the preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Before the description, it should be understood that the terms used in the specification and the appended claims should not be interpreted as limited to the general and dictionary meanings, but should be interpreted based on the principle of allowing the inventor to appropriately define the terms for the best interpretation, based on the meaning and concept corresponding to the technical level of the present invention. Therefore, the description herein is only a preferred example for illustrative purposes, and is not intended to limit the scope of the present invention, so it should be understood that other equivalent implementations and modifications can be made without departing from the spirit and scope of the present invention.

[0043] In this document, the terms "include", "including", "have", "contain" or any other similar terms are open conjunctions, which are intended to cover non-exclusive inclusions. For example, a composition or product containing multiple elements is not limited to the elements listed herein, but may also include other elements that are not explicitly listed but are generally inherent to the composition or product. In addition, unless otherwise explicitly stated, the term "or" refers to an inclusive "or" rather than an exclusive "or". For example, any of the following situations satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist), A is false (or does not exist) and B is true (or exists), and A and B are both true (or exist). In addition, in this document, the interpretation of the terms "include", "including", "have", and "contain" should be considered to have been specifically disclosed and simultaneously cover closed or semi-closed conjunctions such as "consisting of" and "consisting essentially of".

[0044] In this article, all features or conditions defined in the form of numerical ranges or percentage ranges are only for brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be deemed to have covered and specifically disclosed all possible secondary ranges and individual values ​​within the range, especially integer values. For example, the range description of "1 to 8" should be deemed to have specifically disclosed all secondary ranges such as 1 to 7, 2 to 8, 2 to 6, 3 to 6, 4 to 8, 3 to 8, etc., especially secondary ranges defined by all integer values, and should be deemed to have specifically disclosed individual values ​​such as 1, 2, 3, 4, 5, 6, 7, 8, etc. within the range. Unless otherwise specified, the above interpretation method applies to all contents of the entire present invention, regardless of whether the range is broad or not.

[0045] If the quantity or other numerical value or parameter is expressed as a range, a preferred range or a series of upper and lower limits, it should be understood that all ranges consisting of any upper limit or preferred value of the range and the lower limit or preferred value of the range have been specifically disclosed herein, regardless of whether these ranges are disclosed separately. In addition, if a numerical range is mentioned herein, unless otherwise specified, the range should include its endpoints and all integers and fractions within the range.

[0046] In this document, under the premise of achieving the purpose of the invention, numerical values ​​should be understood to have the accuracy of the number of significant digits of the numerical value. For example, the number 40.0 should be understood to cover the range from 39.50 to 40.49.

[0047] In the zinc-air capacitor battery with a dual positive electrode structure according to the present invention, the positive electrode is a dual positive electrode structure composed of a capacitor electrode and an air electrode. The introduction of the capacitor electrode provides more surface area for electron transmission, reduces the charge transfer impedance of the electrode, thereby reducing the internal resistance of the battery and improving the battery discharge efficiency; at the same time, it also increases the battery's capacitance, thereby improving the battery's energy storage capacity and power density, allowing the battery to release stored energy faster; in addition, the capacitor electrode can respond to the battery discharge or charging needs faster, improving the response speed and dynamic characteristics of the zinc-air battery; finally, the addition of the capacitor electrode can increase the charge transfer rate between the electrode material and the electrolyte, promote the electrochemical reaction in the battery, and thus increase the battery's energy transfer rate. In general, a capacitor electrode is connected in parallel to the positive electrode of the zinc-air battery to improve the battery's performance and enhance the battery's performance and stability.

[0048] The following examples are only listed as examples of embodiments of the present invention and do not constitute any limitation to the present invention. It can be understood by those skilled in the art that modifications within the scope of the essence and concept of the present invention fall within the scope of protection of the present invention. Unless otherwise specified, the reagents and instruments used in the following examples are all commercially available products.

[0049] The sandwich zinc-air battery mold used in the embodiment was purchased from Changsha Spring New Energy Technology Co., Ltd., model OMS-C, and the positive electrode active area was 1 cm 2 The active area of ​​the negative electrode is 2 cm 2 The distance between the positive and negative electrodes is 10 mm, and the electrolyte carrying capacity is approximately 1.5 mL.

[0050] In the embodiment, during long-term battery testing, a waterproof breathable membrane is used to cover the positive electrode to prevent electrolyte leakage while ensuring air circulation, thereby reducing the volatilization of electrolyte during long-term battery operation. The waterproof breathable membrane was purchased from Changsha Spring New Energy Technology Co., Ltd. and is made of polytetrafluoroethylene.

[0051] Example 1

[0052] This embodiment provides a neutral dual positive electrode structure zinc-air capacitor battery, and its structural schematic diagram is as follows: Figure 1 As shown, the battery structure includes a zinc metal negative electrode, a neutral electrolyte, an air positive electrode, and a capacitor positive electrode. The preparation and assembly process is as follows:

[0053] (1) Preparation of air cathode:

[0054] Conductive carbon black (VULCAN XC-72R) and polytetrafluoroethylene were uniformly mixed in an ethanol solvent at a mass ratio of 90:10, and then coated on a circular carbon paper with a diameter of 12 mm, and then vacuum dried at a temperature of 80°C for 12 h. The loading amount of the air positive electrode was controlled at 5±0.5 mg / cm 2 ;

[0055] (2) Preparation of capacitor electrodes:

[0056] Commercial YP-50F, acetylene black and polytetrafluoroethylene were uniformly mixed in an ethanol solvent at a mass ratio of 85:10:5, and then coated on a circular carbon paper with a diameter of 12 mm, and then vacuum dried at a temperature of 80°C for 12 hours. The capacitance electrode loading was controlled at 10±1 mg / cm 2 ;

[0057] (3) Preparation of electrolyte:

[0058] In this embodiment, a 1 mol / L zinc trifluoromethanesulfonate aqueous solution is prepared as the electrolyte of the zinc air capacitor battery;

[0059] (4) Battery assembly

[0060] The zinc sheet, capacitor electrode and air electrode are placed on the mold in order, a waterproof and breathable film is covered on the positive electrode, the electrode is extended with a wire for easy testing, and the mold is tightened with screws. The electrolyte is injected into the middle cavity of the mold, and then the liquid inlet is sealed with a rubber plug.

[0061] The prepared dual-cathode zinc-air capacitor battery was electrochemically tested. 2 In the case of , the charge and discharge curves of different current densities are as follows Figure 2 As shown. Under the same conditions, the zinc-air battery without the introduction of capacitor electrodes ( Figure 3 ) compared, the charge and discharge overpotential of the zinc-air capacitor battery is significantly reduced; and when the current increases to 4mA / cm 2 When the voltage is cut off at 0.6V, the capacity of the zinc-air capacitor battery also increases significantly. Figure 4 It can also be shown that the electrochemical activity of the zinc-air capacitor battery is greatly increased after the introduction of the capacitor electrode. Figure 5It can be seen that the power density and energy density of the dual positive electrode structure zinc-air capacitor battery are improved compared with zinc-air batteries and zinc capacitors. Figure 6-7 This shows that the zinc-air capacitor battery has good cycle performance, with a limited capacity of 2mAh / cm 2 When 0.1mA / cm 2 The current density of charging and discharging can be stably operated for more than 2000h. Figure 8 When the dual-positive electrode zinc-air capacitor battery is discharged alternately with a current of 0.1mA and 2mA, the voltage and output power change over time, indicating that the battery can achieve conversion between high power and low power during the discharge process, so that it can flexibly respond to needs when powering equipment.

[0062] Example 2

[0063] This embodiment provides a neutral dual-positive electrode structure zinc-air capacitor battery, and its assembly process refers to that of Example 1. The difference from Example 1 is that in this embodiment, a 1 mol / L zinc acetate aqueous solution is used as the electrolyte.

[0064] Using 1 mol / L zinc acetate aqueous solution as the electrolyte, the charge and discharge capacity is limited to 2 mAh / cm 2 In the case of , the charge and discharge curves of different current densities are as follows Fig. 9 As shown. Under the same conditions, the zinc-air battery without the introduction of capacitor electrodes ( Fig.10 ), the charge and discharge overpotential of the zinc-air capacitor battery is also reduced, indicating that the measure of introducing capacitor electrodes to improve battery performance is also effective for the zinc-air battery system with zinc acetate aqueous solution as the electrolyte.

[0065] Example 3

[0066] This embodiment provides a neutral dual positive electrode structure zinc-air capacitor battery, and its assembly process is referred to Example 1. The difference from Example 1 is that in this embodiment, Ketjen black is used as the carbon material of the air electrode. 2 , 0.4mA / cm 2 The charge and discharge curves of the neutral zinc-air battery (without dual positive electrode structure, i.e., without capacitor electrode) and the neutral dual positive electrode structure zinc-air capacitor battery at a current density of Fig.11 ) It can be seen that the charge and discharge overpotential of the neutral zinc-air capacitor is significantly reduced, indicating that the measure of introducing capacitor electrodes to improve battery performance is also effective for the zinc-air battery system using Ketjen black as the air positive electrode carbon material.

[0067] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A zinc-air capacitor battery based on a dual positive electrode structure, comprising a zinc metal negative electrode, a neutral electrolyte, an air electrode and a capacitor electrode, wherein the air electrode and the capacitor electrode are positive electrodes connected in parallel.

2. The zinc-air capacitor battery based on a dual positive electrode structure according to claim 1, characterized in that: The negative electrode adopts zinc metal as active material; zinc sheet, zinc foil, zinc block and various materials compounded with zinc metal can be used as the negative electrode of the zinc-air capacitor battery.

3. The zinc-air capacitor battery based on a dual positive electrode structure according to claim 1, characterized in that: The electrolyte is a zinc salt aqueous solution, wherein the solute of the zinc salt aqueous solution is one or more of zinc sulfate, zinc chloride, zinc acetate, zinc trifluoromethanesulfonate and zinc bis(trifluoromethylsulfonyl)imide; the concentration of the zinc salt solution is 0.2 to 5 mol / L, preferably 0.5 to 2 mol / L.

4. The zinc-air capacitor battery based on a dual positive electrode structure according to claim 1, characterized in that: The air electrode is an electrode loaded with carbon material on the surface of the current collector, with a loading amount of 1 to 8 mg / cm 2 The capacitor electrode is an electrode loaded with carbon material on the surface of the current collector, and the loading amount is 1 to 20 mg / cm 2 .

5. The zinc-air capacitor battery based on a dual positive electrode structure according to claim 4, characterized in that: The carbon material is selected from at least one of conductive carbon black, porous carbon, activated carbon, carbon nanotubes, and activated carbon fibers.

6. The zinc-air capacitor battery based on a dual positive electrode structure according to claim 4, characterized in that: The current collector includes one of foamed nickel, carbon paper and stainless steel mesh.

7. The method for preparing a zinc-air capacitor battery based on a dual positive electrode structure according to any one of claims 1 to 6, comprising the following steps: (1) Preparation of dual positive electrodes: dispersing carbon material and binder in a solvent, mixing to form a slurry, applying the slurry to a current collector, and drying to obtain an air electrode; The carbon material, the binder and the conductive additive are dispersed in a solvent, mixed to form a slurry, the slurry is applied to a current collector, and dried to obtain a capacitor electrode; (2) Assembly of zinc-air capacitor battery based on dual positive electrode structure: Assemble in the order of zinc sheet, air electrode, and capacitor electrode, and add electrolyte to obtain a dual positive electrode structure zinc-air capacitor battery.

8. The preparation method according to claim 7, characterized in that: In the air electrode preparation process of step (1), the mass ratio of the carbon material to the binder is (8-10):1; more preferably, the mass ratio of the carbon material to the binder is 9:1; Preferably, in the capacitor electrode preparation process of step (1), the mass ratio of the carbon material, the conductive additive and the binder is (15-20):(1.5-2.5):1; further preferably, the mass ratio of the carbon material, the conductive additive and the binder is 85:10:5; Preferably, the current collector in step (1) comprises one of nickel foam, carbon paper and stainless steel mesh; Preferably, the binder in step (1) comprises one or more of sodium carboxymethyl cellulose, polytetrafluoroethylene and polyvinylidene fluoride; Preferably, the conductive additive in step (1) comprises one or more of carbon black, acetylene black, Ketjen black, conductive graphite and carbon nanotubes; Preferably, the dispersant in step (1) comprises one or more of water, ethanol and N-methylpyrrolidone.

9. Use of a dual positive electrode structure in a zinc-air capacitor battery, wherein the dual positive electrode structure comprises an air electrode and a capacitor electrode connected in parallel.

10. The use according to claim 9, characterized in that The air electrode is an electrode loaded with carbon material on the surface of the current collector, with a loading amount of 1 to 8 mg / cm 2 The capacitor electrode is an electrode loaded with carbon material on the surface of the current collector, and the loading amount is 1 to 20 mg / cm 2 ; Preferably, the carbon material is selected from at least one of conductive carbon black, porous carbon, activated carbon, carbon nanotubes, and activated carbon fibers; Preferably, the current collector comprises one of nickel foam, carbon paper and stainless steel mesh.

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