Sulfur-based aqueous ferrous ion battery assembled in non-inert gas environment

Abstract

The invention provides a sulfenyl aqueous ferrous ion battery assembled in a non-inert gas environment. The sulfenyl aqueous ferrous ion battery mainly comprises a sulfur-containing positive electrode, an iron-containing negative electrode, a ferrous ion-containing electrolyte and a diaphragm. The charging and discharging process of the battery relates to an oxidation-reduction reaction between ferrous ions and a sulfur-containing positive electrode, and the battery has the electrochemical characteristic of two-electron transfer. The sulfur-based aqueous ferrous ion battery successfully solves the problems of serious battery polarization and poor rate capability caused by low conductivity of elemental sulfur, and inhibits oxidation failure of ferrous ions in the electrolyte, so that the battery does not need to be assembled in an oxygen-free inert gas glove box; therefore, the cost and the process complexity of the battery are greatly reduced, the specific capacity of the battery calculated based on the positive and negative active substances (N / P = 1) reaches 517 mAh g <-1 >, and the energy density reaches 191 Wh kg <-1 >. The invention provides an important technical support for the practicability of the sulfenyl aqueous ferrous ion battery.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal secondary batteries, in particular, to a sulfur-based aqueous ferrous ion battery assembled in a non-inert gas environment. BACKGROUND

[0002] Lithium-sulfur batteries are considered as one of the most promising candidates in the next generation of electrochemical energy storage due to the high theoretical capacity (1675 mAh g -1 ) of the sulfur cathode, low cost (0.1 $ kg ~ ) and environmental friendliness. -1 However, the low electrical conductivity (5×10 -28 S m -1 ) of the sulfur cathode, the polysulfide shuttle effect and the potential safety hazard of the organic electrolyte are the main challenges faced by the development of lithium-sulfur batteries. The development of sulfur-based aqueous batteries can not only release the high theoretical capacity of the sulfur cathode, but also ensure the safety of the battery.

[0003] In recent years, with the excavation and matching of a series of transition metal elements, a large number of new types of aqueous metal-sulfur batteries have been reported one after another, and have shown unique energy storage characteristics. For example, zinc-sulfur batteries have a reversible specific capacity of 1200 mAh g -1 , and the solid-solid phase transition between sulfur (S) and zinc sulfide (ZnS) during charging and discharging effectively avoids the dissolution of polysulfides and the loss of active materials. However, the zinc element has a low reserve in the earth (52-83 ppm), which limits its wide application. In contrast, iron, a transition metal, has a very high crustal element abundance (50,000 ppm) and exhibits a lower hydrogen standard reduction electrode potential (-0.44 V vs. SHE) and a higher theoretical specific capacity (960 mAh g -1 ), so iron has the potential to be used as an anode material for aqueous batteries. The aqueous iron-sulfur battery composed of a sulfur cathode and an iron anode not only has a high theoretical capacity, but also has a very low manufacturing cost.

[0004] However, this system still faces two major challenges. First, the intrinsic electrical conductivity of elemental sulfur is extremely low, which leads to a large polarization and slow kinetic response of the phase transition reaction between sulfur and iron sulfide, thereby limiting the rate performance of the battery. Second, ferrous ions (Fe 2+ ) in the electrolyte are easily oxidized to (Fe 3+ ), which leads to the failure of the electrolyte, so the battery must be assembled in an oxygen-free inert glove box, which increases the manufacturing cost and the complexity of the process. Therefore, breakthroughs in the above two major challenges will promote the development of sulfur-based aqueous iron ion batteries in the energy storage field and provide important technical support for the development of the next generation of low-cost and high-safety aqueous batteries. SUMMARY

[0005] In view of the defects in the prior art, the purpose of the present application is to provide a sulfur-based aqueous ferrous ion battery assembled in a non-inert gas environment.

[0006] The sulfur-based aqueous ferrous ion battery according to the present application has the characteristics of being assembled in a non-inert gas environment, high intrinsic conductivity and high specific capacity, and comprises a sulfur-containing positive electrode coated on a current collector, a ferrous negative electrode, a ferrous ion electrolyte and a separator.

[0007] The current collector is responsible for efficiently collecting and conducting the electrons generated in the electrode material to the external circuit, providing mechanical support for the active material, preventing the electrode material from falling off and deforming during charging and discharging, maintaining the stability of the electrode structure, and effectively reducing the battery resistance, improving the charging and discharging efficiency of the battery, and reducing energy loss.

[0008] Preferably, the material of the current collector is one or more of carbon, titanium and nickel.

[0009] Preferably, the preparation method of the sulfur-containing positive electrode comprises the following steps: S1: mixing sulfur material and carbon material according to a certain mass ratio, controlling the carbon content to be 10-80 wt%, and obtaining sulfur-carbon composite material by melt diffusion method; S2: mixing the sulfur-carbon composite with a binder and a conductive agent, the addition amount of the binder and the conductive agent being not more than 30 wt%, and then adding ethanol to obtain a mixed slurry; S3: coating the mixed slurry on the current collector, drying and cutting the piece for standby use.

[0010] Preferably, the sulfur material is one or more of sulfur, selenium, sulfur-selenium intermetallic compound, (poly) ferrous sulfide and (poly) ferrous selenide.

[0011] Preferably, the carbon material is one or more of microporous carbon, mesoporous carbon, activated carbon, hierarchical porous carbon, carbon nanotube, graphene, graphite, Ketjen black, acetylene black, Super-P, carbon sphere and heteroatom treatment modification.

[0012] Preferably, the binder is one or more of polytetrafluoroethylene, polyvinylidene fluoride, butadiene rubber, sodium carboxymethyl cellulose, polyacrylic acid, sodium polyacrylate, sodium alginate and polyvinyl alcohol.

[0013] Preferably, the conductive agent is one or more of acetylene black, Super-P, Ketjen black, carbon nanotube, graphene, carbon fiber, graphite and metal powder.

[0014] Preferably, the iron-containing negative electrode is metallic iron foil, metallic iron powder, foamed iron, and metallic iron loaded on a conductive current collector, which includes but is not limited to one of carbon materials, metals, or non-metallic materials.

[0015] Preferably, the ferrous ion electrolyte is an aqueous solution of ferrous perchlorate, in which the concentration of ferrous ions is 0.01-20 mol / L. -1 The amount of electrolyte added is related to the capacity of the battery, and the amount of electrolyte added is 1-20 ml Ah -1 .

[0016] Preferably, the material of the separator is cellulose, glass fiber, or porous polyolefin.

[0017] The working principle and characteristics of the sulfur-based aqueous ferrous ion battery assembled in a non-inert gas environment according to the present application are as follows: During discharging, the sulfur selenium intercalation compound in the sulfur-containing positive electrode obtains electrons and combines with Fe 2+ in the electrolyte to form FeS and FeSe, and Fe in the negative electrode material loses electrons to generate Fe 2+ into the electrolyte.

[0018] During charging, FeS and FeSe in the sulfur-containing positive electrode lose electrons and are converted into S and Se, respectively, and Fe 2+ dissolves back into the electrolyte, and Fe 2+ in the electrolyte is reversibly deposited into the negative electrode material.

[0019] Compared with the prior art, the present application has the following beneficial effects: 1. The sulfur-based aqueous ferrous ion battery assembled in a non-inert gas environment according to the present application uses a novel ferrous perchlorate as an electrolyte, which can effectively prevent ferrous ions from being oxidized by dissolved oxygen in the electrolyte and oxygen in the air environment due to its special solvation structure, thereby completely solving the current situation that aqueous ferrous ion batteries are assembled in an inert gas glove box, and greatly reducing the manufacturing cost and process complexity of the battery. 2. The sulfur-based aqueous ferrous ion battery assembled in a non-inert gas environment according to the present application uses sulfur selenium intercalation compound as the active material of the positive electrode, and utilizes the high electrical conductivity of selenium to significantly improve the intrinsic conductivity of the positive electrode material, thereby ensuring that the sulfur-based aqueous battery has excellent rate performance and good cycle stability. 3. The sulfur-based aqueous ferrous ion battery assembled in a non-inert gas environment according to the present application has the characteristics of safety, low cost, high energy density, long service life, and chargeability, and has great research value and application prospect in the field of energy storage. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to make the technical solutions of the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description only need to explain the embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative effort based on the provided drawings. Other features, objects and advantages of the present application will become more apparent from the following detailed description of the non-limiting embodiments with reference to the accompanying drawings: Figure 1 is a working schematic diagram of a sulfur-based aqueous ferrous ion battery assembled in a non-inert gas environment provided by the present application; Figure 2 is a rate performance diagram of a sulfur-based aqueous ferrous ion battery assembled in a non-inert gas environment in embodiment 1 of the present application; Figure 3 is a cycle performance diagram of a sulfur-based aqueous ferrous ion battery assembled in a non-inert gas environment in embodiment 1 of the present application at 0.5 A g -1 Figure 4 is a typical charge-discharge curve of a sulfur-based aqueous ferrous ion battery assembled in a non-inert gas environment in embodiment 2 of the present application; Figure 5 is a typical charge-discharge curve of a sulfur-based aqueous ferrous ion battery assembled in a non-inert gas environment in embodiment 3 of the present application; Figure 6 is a typical charge-discharge curve of a sulfur-based aqueous ferrous ion battery assembled in a non-inert gas environment in embodiment 4 of the present application. DETAILED DESCRIPTION

[0021] The present application will be described in detail below with specific embodiments. The following embodiments will help those skilled in the art to further understand the present application, but do not limit the present application in any form. It should be noted that for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made. These all belong to the protection scope of the present application.

[0022] It should be noted that when an element is referred to as "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element. In addition, the connection can be for fixing or for circuit communication.

[0023] ​It should be understood that the terms "length", "width", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate directions or positions based on the directions or positions shown in the drawings, and are used only for the purpose of facilitating the description of the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0024] In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more of the features. In the description of the embodiments of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly and specifically limited.

[0025] The features and performances of the present application are further described in detail below in combination with embodiments.

[0026] Embodiment 1 In the embodiments of the present application, the present application provides a sulfur-based aqueous ferrous ion battery assembled in a non-inert gas environment, comprising: A positive electrode material, and the preparation method thereof is specifically as follows: 40 wt% selenium disulfide powder is uniformly mixed with 60 wt% activated carbon and ground for 30 minutes, and then the mixture is placed in a vacuum glass tube and kept at 250 ℃ for 10 hours to obtain a sulfur-carbon composite material; the sulfur-carbon composite material, Super-P (conductive carbon black) and polytetrafluoroethylene dispersion liquid are mixed and ground in a ratio of 8:1:1 for 30 minutes, and an ethanol solution is added to obtain a slurry, which is coated on a current collector carbon paper and dried in a 60 ℃ vacuum drying oven overnight, and then cut into a 12 mm diameter disc to serve as a positive electrode sheet.

[0027] A negative electrode material, and the preparation method thereof is specifically as follows: a 1 mm thick foam iron is cut into a 12 mm diameter disc for use.

[0028] A battery assembly, and the method thereof is specifically as follows: a CR2032 type button cell is used, the positive electrode shell is placed upward, the sulfur positive electrode is placed, then a glass fiber diaphragm is placed, 130 μL of 0.5 mol L -1 of ferrous perchlorate electrolyte is added dropwise, the foam iron negative electrode is placed, the gasket is placed, the shrapnel is placed, the negative electrode shell is covered, and a pressure of 50 kg cm -2 is applied to obtain a sulfur-based aqueous ferrous ion battery, and finally electrochemical test is performed on a new wei battery test system.

[0029] Figure 2This is a rate performance diagram of the battery in this embodiment. The battery is at 0.5 A g. -1 It showed a current density of 854.5 mAh g. -1 High reversible capacity, even at 5 A g -1 It can still release up to 726.4 mAh g at a current density. -1 The reversible capacity, and the coulombic efficiency of the battery is always close to 100%; in addition, such as Figure 3 As shown, the battery still maintains 729.1 mAh g after 100 cycles. -1 The discharge capacity retention rate reached 88.4%. Example 2 In an embodiment of the present invention, the sulfur-based aqueous ferrous ion battery assembled in a non-inert gas environment provided by the present invention includes: The cathode material is prepared by mechanically grinding selenium powder and sulfur powder at a molar ratio of 6:2 for 30 minutes. The resulting mixture is then placed in a vacuum glass tube and incubated at 5°C for 1 minute. -1 The temperature was rapidly increased to 450℃ and maintained for 10 hours, then cooled to room temperature to obtain a sulfur-selenium intermetallic compound named Se6S2. 40 wt% Se6S2 powder was uniformly mixed with 60 wt% activated carbon and ground for 30 minutes. The mixture was then placed in a high-pressure reactor and kept at 210℃ for 10 hours to obtain a sulfur-carbon composite material. The sulfur-carbon composite material, Super-P, and polytetrafluoroethylene dispersion were mixed in a ratio of 8:1:1 and ground for 30 minutes. An ethanol solution was added to obtain a slurry. The slurry was coated onto current collector carbon paper and dried overnight in a vacuum drying oven at 60℃. The resulting discs were cut into 12 mm diameter rounds to serve as positive electrode plates.

[0030] The negative electrode material is prepared by cutting 1 mm thick foamed iron into 12 mm diameter circular pieces.

[0031] The battery assembly method is as follows: using a CR2032 button cell, with the positive electrode shell facing upwards, place the sulfur positive electrode, followed by a glass fiber separator, and then add 130 μL of 0.5 mol / L solution. -1 Ferrous perchlorate electrolyte, place the foamed iron negative electrode, place the gasket, place the spring, cover with the negative electrode shell, and apply 50 kg cm⁻¹. -2 A sulfur-based aqueous ferrous ion battery was obtained under pressure, and finally, electrochemical tests were conducted on the Newway battery testing system.

[0032] Figure 4 The battery in this embodiment typically operates at 0.5 A g. -1 Charge-discharge curves of the battery at current densities of 0.5 Ag. -1a high reversible capacity of 448.6 mAh g -1 at a current density of 0.5 A g

[0033] Example 3 In the embodiment of the present application, the present application provides a sulfur-based aqueous ferrous ion battery assembled in a non-inert gas environment, comprising: a positive electrode material, the preparation method thereof is specifically as follows: 40 wt% of sulfur powder and 60 wt% of activated carbon are uniformly mixed and ground for 30 minutes, and then the mixture is placed in a high-pressure reaction kettle, and is kept at 155 °C for 10 hours to obtain a sulfur-carbon composite material; the sulfur-carbon composite material, Super-P and polytetrafluoroethylene dispersion liquid are mixed and ground for 30 minutes at a ratio of 8:1:1, and an ethanol solution is added to obtain a slurry, the slurry is coated on a current collector carbon paper, and is dried in a 60 °C vacuum drying box overnight, and is cut into a 12 mm diameter disc to be used as a positive electrode sheet.

[0034] a negative electrode material, the preparation method thereof is specifically as follows: a 1 mm thick foam iron is cut into a 12 mm diameter disc to be used battery assembly, the method thereof is specifically as follows: a CR2032 type button cell is used, the positive electrode shell is upward, the sulfur positive electrode is placed, then a glass fiber diaphragm is placed, 130 μL of 0.5 mol L -1 of a high-chloric acid ferrous electrolyte is added dropwise, the foam iron negative electrode is placed, a gasket is placed, a spring is placed, the negative electrode shell is covered, and a pressure of 50 kg cm -2 is applied to obtain a sulfur-based aqueous ferrous ion battery, and finally electrochemical test is performed on a new battery test system.

[0035] Figure 5 The charge-discharge curve of the battery in this embodiment is typical at a current density of 0.5 A g -1 , the battery shows a high reversible capacity of 1213.0 mAh g -1 at a current density of 0.5 A g -1 , and the coulombic efficiency of the battery is close to 100%.

[0036] Example 4 In the embodiment of the present application, the present application provides a sulfur-based aqueous ferrous ion battery assembled in a non-inert gas environment, comprising: The specific preparation method of the positive electrode material is as follows: 40 wt% selenium powder and 60 wt% activated carbon are uniformly mixed and ground for 30 minutes. Then, the mixture is placed in a vacuum glass tube and kept at 260 ℃ for 10 hours to obtain a selenium-carbon composite material. Sulfur-carbon composite material, Super-P and polytetrafluoroethylene dispersion are mixed in a ratio of 8:1:1 and ground for 30 minutes. An ethanol solution is added to obtain a slurry. The slurry is coated onto current collector carbon paper and dried overnight in a vacuum drying oven at 60 ℃. The resulting discs are cut into 12 mm diameter round pieces to serve as positive electrode sheets.

[0037] The negative electrode material is prepared by cutting 1 mm thick foamed iron into 12 mm diameter circular pieces. The battery assembly method is as follows: using a CR2032 button cell, with the positive electrode shell facing upwards, place the sulfur positive electrode, followed by a glass fiber separator, and then add 130 μL of 0.5 mol / L solution. -1 Ferrous perchlorate electrolyte, place the foamed iron negative electrode, place the gasket, place the spring, cover with the negative electrode shell, and apply 50 kg cm⁻¹. -2 A sulfur-based aqueous ferrous ion battery was obtained under pressure, and finally, electrochemical tests were conducted on the Newway battery testing system.

[0038] Figure 6 The battery in this embodiment typically operates at 0.5 A g. -1 Charge-discharge curves of the battery at current densities of 0.5 Ag. -1 It showed a current density of 347.3 mAh g⁻¹. -1 It has a high reversible capacity and the coulombic efficiency of the battery is close to 100%.

[0039] In summary, this invention, through a novel sulfur cathode design, electrolyte selection, and anode matching method, has developed a sulfur-based aqueous ferrous ion battery that is resistant to air oxidation and can be assembled in the environment. This battery utilizes Fe... 2+ Using the charge carrier as the carrier, and based on the reversible phase transformation of the positive electrode sulfur-selenium intermetallic compound SeS2 with FeS and FeSe, and the reversible deposition / stripping process of the negative electrode, high energy density and power density were achieved. The specific capacity of the battery based on the total mass (N / P=1) of the positive and negative electrode active materials reached 517 mAh g. -1 The energy density reaches 191 Wh kg. -1 The various embodiments described in this specification are intended to be illustrative of the invention and do not limit the scope of the invention. Although specific embodiments have been described in detail, various modifications can be made to these details without departing from the spirit or scope of the application. Accordingly, it is intended that all such alternatives, modifications and variations be included within the scope of the following claims. The claims are intended to cover all adoptions of the application in which a patented process, machine, manufacture, or composition of matter is practiced.

[0040] The specific embodiments of the present application have been described. It is to be understood that the application is not limited to the specific embodiments described and that various modifications made to the embodiments can be made without departing from the spirit or scope of the application.

Claims

1. A sulfur-based aqueous ferrous ion battery assembled in a non-inert gas environment, characterized in that, This includes a sulfur-containing positive electrode, an iron-containing negative electrode, an electrolyte containing ferrous ions, and a diaphragm coated on the current collector; The sulfur-containing positive electrode is a sulfur-containing mixture, comprising a sulfur-containing carbon material composite with a carbon content of 10-80 wt%, a conductive agent with a carbon content of 10-20 wt%, and a binder with a carbon content of 10-20 wt%.

2. The sulfur-based aqueous ferrous ion battery assembled in a non-inert gas environment according to claim 1, characterized in that, The sulfur-containing mixture contains sulfur materials in one or more of the following forms: sulfur, selenium, sulfur-selenium intermetallic compound, ferrous sulfide, and ferrous selenide.

3. The sulfur-based aqueous ferrous ion battery assembled in a non-inert gas environment according to claim 1, characterized in that, The carbon material in the sulfur-containing mixture is one or more of the following: microporous carbon, mesoporous carbon, activated carbon, hierarchical porous carbon, carbon nanotubes, graphene, graphite, Ketjen black, acetylene black, Super-P, carbon spheres, and heteroatom-treated modified products of the above carbon materials.

4. The sulfur-based aqueous ferrous ion battery assembled in a non-inert gas environment according to claim 1, characterized in that, The current collector is made of one or more of carbon, titanium, and nickel.

5. The sulfur-based aqueous ferrous ion battery assembled in a non-inert gas environment according to claim 1, characterized in that, The conductive agent is one or more of the following: acetylene black, Super-P, Ketjen black, carbon nanotubes, graphene, carbon fiber, graphite, and metal powder.

6. The sulfur-based aqueous ferrous ion battery assembled in a non-inert gas environment according to claim 1, characterized in that, The adhesive is one or more of the following: polytetrafluoroethylene, polyvinylidene fluoride, styrene-butadiene rubber, sodium carboxymethyl cellulose, polyacrylic acid, sodium polyacrylate, sodium alginate, and polyvinyl alcohol.

7. The sulfur-based aqueous ferrous ion battery assembled in a non-inert gas environment according to claim 1, characterized in that, The iron-containing negative electrode is a metallic iron foil, metallic iron powder, foamed iron, or elemental metallic iron supported on a current collector. The current collector includes, but is not limited to, one or more of carbon materials, metals, or non-metallic materials.

8. The sulfur-based aqueous ferrous ion battery assembled in a non-inert gas environment according to claim 1, characterized in that, The ferrous ion-containing electrolyte is an aqueous solution of a soluble ferrous salt, with a ferrous ion concentration of 0.1–5 mol. . L -1 The amount of electrolyte added is 1~20 ml. . Ah -1 .

9. The sulfur-based aqueous ferrous ion battery assembled in a non-inert gas environment according to claim 1, characterized in that, The membrane is made of cellulose, glass fiber, or porous polyolefin.

10. The sulfur-based aqueous ferrous ion battery assembled in a non-inert gas environment according to claim 1, characterized in that, The method for preparing the sulfur-containing cathode includes the following steps: S1: Sulfur materials and carbon materials are mixed in a certain mass ratio, and the carbon content is controlled at 10~80 wt%. Sulfur-carbon composite materials are obtained by melt diffusion method. S2: The sulfur-carbon composite is mixed with a binder and a conductive agent, with the amount of binder and conductive agent added not exceeding 30 wt%, and then ethanol is added to obtain a mixed slurry; S3: Apply the mixed slurry to the current collector, dry it, and cut it into pieces for later use.

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