Aqueous iron ion battery

Abstract

The present invention discloses an aqueous iron ion battery, wherein the positive electrode comprises a ferrous vanadate positive electrode material and the electrolyte is an aqueous electrolyte. The ferrous vanadate positive electrode material in the aqueous iron ion battery of the present invention contains ferrous ions, which can provide sufficient working ions for the aqueous iron ion battery. The negative electrode can use a non-ferrous negative electrode material, thereby avoiding the problem of side reactions between the metallic iron negative electrode and the aqueous electrolyte, and is suitable for large-scale commercial applications.

Description

Technical Field

[0001] The present invention relates to the technical field of secondary batteries, and in particular to an aqueous iron ion battery. Background Art

[0002] With the continuous development of human society, the substantial increase in energy supply and demand and the increasing severity of environmental pollution have become two major issues that need to be addressed urgently. The large-scale development and utilization of low-pollution, sustainable, intermittent energy sources such as wind, solar, and tidal energy has the potential to fundamentally resolve these issues. One of the keys to large-scale development and utilization of intermittent energy is the establishment of high-quality energy storage systems.

[0003] Lithium-ion batteries have the advantage of high energy density and are energy storage devices that have been widely used. However, there are major bottlenecks in the further application of lithium-ion batteries, as follows: 1) The scarcity of lithium resources and the large consumption of lithium elements have limited the total production capacity of lithium batteries, and the high cost of battery raw materials has led to high battery prices; 2) The electrolyte and battery materials are highly toxic. Once leaked, they will not only cause environmental pollution, but also harm the human body, which also makes the production conditions of batteries extremely harsh; 3) Lithium-ion batteries have safety hazards such as combustion and explosion (for example: short-circuit spontaneous combustion accidents of electric vehicle batteries have cast a shadow on the development of lithium-ion batteries). Therefore, researchers at home and abroad have begun to develop safer and lower-cost Fe 2+ / Mg 2+ / Ca 2+ / Zn 2+ / Al 3+ Aqueous secondary batteries such as lithium-ion batteries are expected to partially replace lithium-ion batteries.

[0004] Aqueous iron ion battery is a kind of battery that uses ferrous ions (Fe 2+ ) as the working ion battery system, and because iron is an element with abundant reserves in the earth's crust, aqueous iron-ion batteries have a good development prospect. At present, the common iron-ion battery consists of a positive electrode (metal oxide, etc.), a negative electrode (metal iron, etc.) and an electrolyte (containing Fe 2+ of neutral aqueous solution) and the Fe 2+ / Fe 0 The double electron reaction has a high specific capacity. Rechargeable aqueous iron ion batteries have the potential for large-scale energy storage applications and have gradually become the focus of researchers. They have great development advantages in the future battery market. According to the embedding / desorption model of multivalent energy storage theory, during discharge, the negative electrode metal Fe loses electrons and becomes Fe 2+, migrate through the electrolyte and embed into the positive electrode material structure. During charging, the ferrous ions are released from the positive electrode material structure and migrate and deposit on the metallic iron negative electrode. However, the metallic iron negative electrode is prone to side reactions with the aqueous electrolyte and is prone to forming iron dendrites during rapid charge and discharge, which poses a risk of causing battery short circuit. In addition, there is Fe 2+ The problems of low utilization rate and poor cycle performance make it difficult to fully meet the actual application needs.

[0005] Therefore, it is of great significance to develop an aqueous iron-ion battery whose positive electrode material itself contains ferrous ions and can provide sufficient working ions for the iron-ion battery (avoiding the use of a metallic iron negative electrode and thus avoiding the side reaction between the metallic iron negative electrode and the aqueous electrolyte). Summary of the Invention

[0006] The object of the present invention is to provide an aqueous iron ion battery.

[0007] The technical solution adopted by the present invention is:

[0008] The invention discloses an aqueous iron ion battery, wherein the positive electrode comprises a ferrous vanadate positive electrode material and the electrolyte is an aqueous electrolyte.

[0009] Preferably, the ferrous vanadate positive electrode material is prepared by the following method:

[0010] 1) mixing an iron source and a vanadium source in a molar ratio of 1:2, mixing with a chelating agent, dispersing in water to form a sol, and then heating and stirring to obtain a wet gel;

[0011] 2) drying the wet gel from step 1) to form a xerogel, pre-calcining the xerogel in a reducing atmosphere or a protective atmosphere, and then grinding the xerogel to obtain a powdered material;

[0012] 3) The powdered material from step 2) is placed in a reducing atmosphere and calcined to obtain a ferrous vanadate positive electrode material.

[0013] Preferably, the iron source in step 1) is at least one of ferrous oxalate, ferrous sulfate, ferric citrate, and ferric oxide.

[0014] Preferably, the vanadium source in step 1) is at least one of ammonium metavanadate, vanadyl sulfate, vanadyl oxalate, vanadyl acetylacetonate, vanadium acetylacetonate, and vanadium pentoxide.

[0015] Preferably, the chelating agent in step 1) is at least one of citric acid, ascorbic acid, oxalic acid, glucose, sucrose, cellulose, and starch.

[0016] Preferably, in step 1), the molar ratio of the vanadium source to the chelating agent is 1:0.5-3.

[0017] Preferably, the heating and stirring in step 1) is carried out at 60°C to 100°C.

[0018] Preferably, the drying in step 2) is carried out at 60°C to 150°C.

[0019] Preferably, the reducing atmosphere in step 2) is one of hydrogen (H2) atmosphere, ammonia (NH3) atmosphere, carbon monoxide (CO) atmosphere, argon-hydrogen (Ar / H2) mixed atmosphere, and helium-hydrogen (He / H2) mixed atmosphere.

[0020] Preferably, the protective atmosphere in step 2) is a nitrogen atmosphere or an argon atmosphere.

[0021] Preferably, the pre-calcination in step 2) is carried out at 300° C. to 500° C., and the pre-calcination time is 3 h to 5 h.

[0022] Preferably, in step 3), the reducing atmosphere is one of hydrogen atmosphere, ammonia atmosphere, carbon monoxide atmosphere, argon-hydrogen mixed atmosphere, and helium-hydrogen mixed atmosphere.

[0023] Preferably, the calcination in step 3) is carried out at 700° C. to 900° C., and the calcination time is 6 h to 12 h.

[0024] Preferably, the aqueous electrolyte is an aqueous solution made of at least one of ferrous sulfate, ferrous chloride, and ferrous ammonium sulfate.

[0025] Preferably, the negative electrode in the aqueous iron ion battery is made of metallic iron (iron foil, iron powder, iron mesh) or carbon material (carbon powder, carbon cloth, carbon mesh).

[0026] Further preferably, the negative electrode of the aqueous iron ion battery is made of carbon material.

[0027] The beneficial effects of the present invention are as follows: the ferrous vanadate positive electrode material in the aqueous iron ion battery of the present invention itself contains ferrous ions, which can provide sufficient working ions for the aqueous iron ion battery, and the negative electrode can use a non-ferrous negative electrode material, thereby avoiding the problem of side reactions between the metallic iron negative electrode and the aqueous electrolyte, and is suitable for large-scale commercial applications.

[0028] Specifically:

[0029] 1) The main component of the ferrous vanadate cathode material in the aqueous iron ion battery of the present invention is ferrous vanadate (FeV2O4). FeV2O4 has a small molecular weight and, combined with the multi-electron reaction of the vanadium element, has a higher charge and discharge capacity than conventional cathode materials.

[0030] 2) The ferrous vanadate cathode material in the aqueous iron ion battery of the present invention is subjected to carbon coating on the particle surface (carbon formed by carbonization of the chelating agent), which can further improve the electrical conductivity and electrochemical activity of the material, thereby effectively improving the electrochemical performance of the cathode material;

[0031] 3) The present invention uses a sol-gel method to prepare ferrous vanadate cathode materials, which has the advantages of simple preparation, convenient operation, low production cost, and easy control of product particle size and morphology, and has good industrialization prospects;

[0032] 4) The ferrous vanadate cathode material in the aqueous iron ion battery of the present invention can provide the ferrous ions required for battery operation, avoiding the use of a metallic iron anode, thereby completely solving all problems caused by the metallic iron anode;

[0033] 5) The cost of the positive and negative electrode materials and aqueous electrolyte of the aqueous iron ion battery of the present invention is low, which is conducive to large-scale commercial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 1 is the X-ray diffraction pattern of the ferrous vanadate positive electrode material in Examples 1 to 3.

[0035] Figure 2 The scanning electron microscope image and carbon element distribution diagram of the ferrous vanadate positive electrode material in Example 1.

[0036] Figure 3 This is the charge and discharge curve of the aqueous iron ion battery of Example 1.

[0037] Figure 4 This is the charge and discharge curve of the aqueous iron ion battery of Example 2.

[0038] Figure 5 This is the charge and discharge curve of the aqueous iron ion battery of Example 3. DETAILED DESCRIPTION

[0039] The present invention will be further explained and illustrated below with reference to specific embodiments.

[0040] Example 1:

[0041] The invention discloses an aqueous iron ion battery, wherein the positive electrode comprises a ferrous vanadate positive electrode material, the negative electrode is made of iron powder, and the electrolyte is a ferrous sulfate aqueous solution.

[0042] The preparation method of the aqueous iron ion battery comprises the following steps:

[0043] 1) Ferrous oxalate (FeC2O4) and ammonium metavanadate (NH4VO3) were weighed in a molar ratio of iron to vanadium of 1:2, and then dissolved in deionized water. Citric acid was then added to a molar ratio of ammonium metavanadate to citric acid of 1:0.5. The mixture was stirred at 60°C until the solids were completely dissolved. The mixture was then stirred at 60°C for 5 h to obtain a wet gel.

[0044] 2) drying the wet gel from step 1) at 70°C in a forced air drying oven to form a xerogel, sintering the xerogel at 300°C in a hydrogen atmosphere for 5 hours, and grinding the xerogel to obtain a powdered material;

[0045] 3) sintering the powdered material from step 2) at 900° C. for 6 h in a hydrogen atmosphere to obtain a ferrous vanadate positive electrode material;

[0046] 4) Dispersing ferrous vanadate cathode material, acetylene black, and polyvinylidene fluoride in a mass ratio of 8:1:1 in N-methylpyrrolidone, coating the resulting film on titanium foil, drying the film thoroughly, and then pressing the film with a tablet press to form the resulting film, which was then cut to obtain battery electrodes.

[0047] 5) In a clean indoor environment, use the battery electrode from step 4) as the positive electrode, the iron sheet as the negative electrode, and a 1 mol / L ferrous sulfate aqueous solution as the electrolyte to encapsulate the battery into a button cell to obtain an aqueous iron ion battery.

[0048] Performance testing:

[0049] 1) The X-ray diffraction (XRD) pattern of the ferrous vanadate cathode material in this embodiment is as follows: Figure 1 shown.

[0050] Depend on Figure 1 It can be seen that the ferrous vanadate positive electrode material in this embodiment contains no impurities and is a pure phase ferrous vanadate positive electrode material with high product purity.

[0051] 2) The scanning electron microscope (SEM) image and carbon element distribution diagram of the ferrous vanadate positive electrode material in this embodiment are as follows Figure 2 shown.

[0052] Depend on Figure 2 It can be seen that the ferrous vanadate positive electrode material in this embodiment is a secondary particle formed by agglomeration of primary particles with a particle size of 100 nm to 500 nm, and the conductive carbon is evenly coated on the surface of the particles.

[0053] 3) The charge and discharge curves of the aqueous iron ion battery of this embodiment at a voltage of 0.2V to 1.8V and a current density of 200mA / g are as follows: Figure 3 shown.

[0054] Depend on Figure 3It can be seen that the charge-discharge specific capacity of the aqueous iron ion battery of this embodiment is relatively high.

[0055] Example 2:

[0056] The invention discloses an aqueous iron ion battery, wherein the positive electrode comprises a ferrous vanadate positive electrode material, the negative electrode is made of carbon powder, and the electrolyte is a ferrous chloride aqueous solution.

[0057] The preparation method of the aqueous iron ion battery comprises the following steps:

[0058] 1) Ferric citrate (FeC6H5O7) and vanadium pentoxide (V2O5) were weighed in a molar ratio of 1:2, and then dissolved in deionized water. Glucose was then added to a molar ratio of 1:1, and the mixture was stirred at 80°C until the solids were completely dissolved. The mixture was then stirred at 80°C for 3 hours to obtain a wet gel.

[0059] 2) drying the wet gel from step 1) at 90°C in a forced air drying oven to form a xerogel, sintering the xerogel at 400°C for 4 hours in a hydrogen atmosphere, and grinding the xerogel to obtain a powdered material;

[0060] 3) sintering the powdered material from step 2) at 800° C. for 9 h in a hydrogen atmosphere to obtain a ferrous vanadate positive electrode material;

[0061] 4) Dispersing ferrous vanadate cathode material, acetylene black, and polyvinylidene fluoride in a mass ratio of 8:1:1 in N-methylpyrrolidone, coating the resulting film on titanium foil, drying the film thoroughly, and then pressing the film with a tablet press to form the resulting film, which was then cut to obtain battery electrodes.

[0062] 5) In a clean indoor environment, using the battery electrode from step 4) as the positive electrode, a carbon powder pressed into a sheet as the negative electrode, and a 1 mol / L ferrous chloride aqueous solution as the electrolyte, the cells are packaged into button cells to obtain an aqueous iron ion battery.

[0063] Performance testing:

[0064] 1) The X-ray diffraction pattern of the ferrous vanadate cathode material in this embodiment is as follows Figure 1 shown.

[0065] Depend on Figure 1 It can be seen that the ferrous vanadate positive electrode material in this embodiment contains no impurities and is a pure phase ferrous vanadate positive electrode material with high product purity.

[0066] 2) The charge and discharge curves of the aqueous iron ion battery of this embodiment at a voltage of 0.2V to 1.8V and a current density of 200mA / g are as follows: Figure 4 shown.

[0067] Depend on Figure 4It can be seen that the charge-discharge specific capacity of the aqueous iron ion battery of this embodiment is relatively high.

[0068] Example 3:

[0069] The invention relates to an aqueous iron ion battery, wherein the positive electrode comprises a ferrous vanadate positive electrode material, the negative electrode is made of carbon cloth, and the electrolyte is an aqueous solution of ferrous ammonium sulfate.

[0070] The preparation method of the aqueous iron ion battery comprises the following steps:

[0071] 1) Ferrous sulfate (FeSO4) and vanadyl oxalate (VOC2O4) were weighed in a molar ratio of 1:2, and then dissolved in deionized water. Cellulose was then added in a molar ratio of 1:0.5, and the mixture was stirred at 70°C until the solids were completely dissolved. The mixture was then stirred at 70°C for 4 hours to obtain a wet gel.

[0072] 2) drying the wet gel from step 1) at 110° C. in a forced air drying oven to form a dry gel, sintering the dry gel at 500° C. in a hydrogen atmosphere for 3 h, and grinding the dry gel to obtain a powdered material;

[0073] 3) sintering the powdered material from step 2) at 700° C. for 12 h in a hydrogen atmosphere to obtain a ferrous vanadate positive electrode material;

[0074] 4) Dispersing ferrous vanadate cathode material, acetylene black, and polyvinylidene fluoride in a mass ratio of 8:1:1 in N-methylpyrrolidone, coating the resulting film on titanium foil, drying the film thoroughly, and then pressing the film with a tablet press to form the resulting film, which was then cut to obtain battery electrodes.

[0075] 5) In a clean indoor environment, use the battery electrode from step 4) as the positive electrode, the carbon cloth as the negative electrode, and a 1 mol / L aqueous solution of ammonium ferrous sulfate as the electrolyte to encapsulate the battery into a button cell to obtain an aqueous iron ion battery.

[0076] Performance testing:

[0077] 1) The X-ray diffraction pattern of the ferrous vanadate cathode material in this embodiment is as follows Figure 1 shown.

[0078] Depend on Figure 1 It can be seen that the ferrous vanadate positive electrode material in this embodiment contains no impurities and is a pure phase ferrous vanadate positive electrode material with high product purity.

[0079] 2) The charge and discharge curves of the aqueous iron ion battery of this embodiment at a voltage of 0.2V to 1.8V and a current density of 200mA / g are as follows: Figure 5 shown.

[0080] Depend on Figure 5It can be seen that the charge-discharge specific capacity of the aqueous iron ion battery of this embodiment is relatively high.

[0081] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. An aqueous iron ion battery, characterized in that: The positive electrode comprises a ferrous vanadate positive electrode material and an aqueous electrolyte. The ferrous vanadate positive electrode material is a secondary particle formed by agglomerating primary particles with a particle size of 100 nm to 500 nm, and conductive carbon is uniformly coated on the surface of the particles. The ferrous vanadate positive electrode material is prepared by the following method: 1) mixing an iron source and a vanadium source in a molar ratio of 1:2, then mixing with a chelating agent and dispersing in water to form a sol, and then heating and stirring to obtain a wet gel; 2) drying the wet gel from step 1) to form a dry gel, pre-calcining the dry gel in a reducing atmosphere or a protective atmosphere, and then grinding the dry gel to obtain a powdered material; 3) calcining the powdered material from step 2) in a reducing atmosphere to obtain a ferrous vanadate positive electrode material.

2. The aqueous iron ion battery according to claim 1, wherein: In step 1), the iron source is at least one of ferrous oxalate, ferrous sulfate, ferric citrate, and ferric oxide.

3. The aqueous iron ion battery according to claim 1 or 2, wherein: Step 1) The vanadium source is at least one of ammonium metavanadate, vanadyl sulfate, vanadyl oxalate, vanadyl acetylacetonate, vanadium acetylacetonate, and vanadium pentoxide.

4. The aqueous iron ion battery according to claim 1 or 2, characterized in that: Step 1) The chelating agent is at least one of citric acid, ascorbic acid, oxalic acid, glucose, sucrose, cellulose, and starch.

5. The aqueous iron ion battery according to claim 1 or 2, wherein: In step 1), the molar ratio of the vanadium source to the chelating agent is 1:0.5-3.

6. The aqueous iron ion battery according to claim 1 or 2, characterized in that: The heating and stirring in step 1) are performed at 60°C to 100°C; and the drying in step 2) is performed at 60°C to 150°C.

7. The aqueous iron ion battery according to claim 1, wherein: The pre-sintering in step 2) is carried out at 300° C. to 500° C. for 3 hours to 5 hours; and the calcining in step 3) is carried out at 700° C. to 900° C. for 6 hours to 12 hours.

8. The aqueous iron ion battery according to any one of claims 1, 2 and 7, wherein: The aqueous electrolyte is an aqueous solution made of at least one of ferrous sulfate, ferrous chloride, and ferrous ammonium sulfate.

9. The aqueous iron ion battery according to any one of claims 1, 2 and 7, wherein: The negative electrode in the aqueous iron ion battery is made of metallic iron or carbon material.

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