Water-based hydrogen solid-state secondary battery with long cycle life and application of water-based hydrogen solid-state secondary battery

Abstract

The invention relates to the technical field of battery energy storage, and discloses an aqueous hydrogen solid secondary battery with long cycle life and application thereof, the battery comprises 50-60% by mass of a hydrogen modified ferrovanadium cyanide composite positive electrode, 10-15% by mass of a platinum carbon negative electrode and 25-40% by mass of a solid electrolyte, the solid electrolyte is composed of an acidic electrolyte and clay in a mass ratio of (0.5-1.5): (1-5), the acidic electrolyte is phosphoric acid or sulfuric acid with the volume concentration of 10%-85%, the clay is selected from two or three of magnesium-based silicate, bentonite and kaolin, and the preparation method of the solid electrolyte comprises the following steps: synthesizing a hydrogen-modified ferrovanadium cyanide / carbon nanotube composite positive electrode material by a solution method; preparing a platinum-carbon catalyst into a negative pole piece; carrying out ball milling on clay and an acidic electrolyte to prepare a solid electrolyte premix, and carrying out film pressing molding; finally, an all-solid-state battery structure with the positive electrode, the solid electrolyte and the negative electrode laminated is assembled in the inert atmosphere, and the battery prepared through the method has the advantages of being long in cycle life and high in safety and is suitable for the field of large-scale energy storage.

Description

Technical Field

[0001] This invention relates to the field of battery energy storage technology, specifically to a long-cycle-life aqueous hydrogen solid-state secondary battery and its applications. Background Technology

[0002] Aqueous secondary batteries, due to their use of water-based electrolytes, have become one of the important development directions in the energy storage field. However, existing aqueous battery technologies still face many bottlenecks: lead-acid batteries pose a risk of heavy metal pollution, nickel hydroxide, the cathode material for nickel-metal hydride batteries, has low abundance in the Earth's crust and is costly, while flow batteries have the potential for electrolyte leakage; although new hydrogen secondary batteries developed since 2018 have achieved significant progress, they still face challenges. + While achieving excellent rate performance for charge carriers, a key drawback remains: limited cathode resources for Ni-H2 batteries. Specifically, both PBA-H2 and LMO-H2 batteries have relatively low specific capacities, making it difficult to meet the high energy density requirements of large-scale energy storage.

[0003] Meanwhile, existing hydrogen batteries mostly use liquid electrolytes, which suffer from problems such as electrolyte evaporation and severe side reactions at the electrode interface. If a single-component solid electrolyte, such as pure polymer, is used, it faces problems such as low ionic conductivity, insufficient mechanical strength, or poor low-temperature performance. In addition, the poor reversibility of proton insertion / extraction in the cathode material and the easy collapse of the crystal structure during cycling further lead to short battery cycle life.

[0004] In light of the above issues, there is an urgent need to develop a high-specific-capacity reversible proton-intercalation / deintercalation cathode material, a high-ion-conductivity-high-stability composite solid electrolyte, and to optimize the preparation process to address the problems of limited resources, low specific capacity, short cycle life, and insufficient performance of solid electrolytes in existing hydrogen rechargeable batteries. Summary of the Invention

[0005] (a) Technical problems to be solved

[0006] To address the shortcomings of existing technologies, this invention provides a long-cycle-life aqueous hydrogen solid-state secondary battery and its application. It has the advantages of high cathode specific capacity, excellent cycle stability, good overall performance of solid electrolyte, and environmentally friendly and low-cost raw materials, thus solving the problems of limited resources, low specific capacity, short cycle life, and insufficient performance of solid electrolyte in existing hydrogen secondary batteries.

[0007] (II) Technical Solution

[0008] To achieve the above objectives, the present invention provides the following technical solution: a long-cycle-life aqueous hydrogen solid-state secondary battery, comprising 50-60% by mass of a hydrogen-modified vanadium iron cyanide composite positive electrode, 10-15% by mass of a platinum carbon negative electrode, and 25-40% by mass of a solid electrolyte.

[0009] Preferably, the solid electrolyte comprises an acidic electrolyte and clay, wherein the mass ratio of the acidic electrolyte to clay in the solid electrolyte is 0.5-1.5:1-5; the volume concentration of the acidic electrolyte is 10%-85%; the acidic electrolyte is selected from phosphoric acid or sulfuric acid; the clay is selected from two or three of magnesium-based silicate clay, bentonite-type clay, and kaolin-type aluminosilicate clay; and the platinum in the platinum-carbon anode accounts for 15%-50% of the total mass of the platinum-carbon anode.

[0010] A long-cycle-life aqueous hydrogen solid-state secondary battery includes the following steps:

[0011] Step 1: Material preparation: Prepare vanadium source, potassium hexacyanoferrate, carboxylated carbon nanotubes, clay, platinum carbon catalyst, conductive agent, binder, titanium mesh, polytetrafluoroethylene mold, acidic electrolyte, hydrochloric acid, ethanol and deionized water.

[0012] Step 2, Material Pretreatment: The vanadium source, potassium hexacyanoferrate, carboxylated carbon nanotubes, clay, platinum-carbon catalyst, conductive agent, binder and titanium mesh are pretreated for later use.

[0013] Step 3, Solution preparation: Prepare vanadium source solution, potassium ferricyanide solution and carbon nanotube dispersion separately;

[0014] Step 4: Preparation of solid electrolyte premix: The pretreated bentonite and acidic electrolyte are added to an agate mortar and manually ground according to the formula mass ratio, and then transferred to a planetary ball mill for ball milling to obtain solid electrolyte premix.

[0015] Step 5, Positive Electrode Active Material: Take the vanadium source solution prepared in Step 2 and add it to the carbon nanotube dispersion prepared in Step 4. Under continuous stirring, add the potassium ferricyanide solution from Step 3 dropwise to the carbon nanotube dispersion. Mix and react in a constant temperature water bath. Wash, centrifuge and vacuum dry the mixed reaction product to obtain hydrogen-modified vanadium ferricyanide composite active material.

[0016] Step 6: Preparation of positive electrode sheet: Mix hydrogen-modified vanadium iron cyanide composite active material, conductive agent and binder in a mass ratio, add ethanol to make a paste, and roll it on a titanium mesh current collector to make a positive electrode sheet;

[0017] Step 7: Preparation of platinum-carbon negative electrode sheet: Mix platinum-carbon negative electrode catalyst powder and binder according to the formula mass ratio, add ethanol to make a slurry, and roll it out on a titanium mesh current collector to make a negative electrode sheet.

[0018] Step 8: Preparation of solid electrolyte membrane: The solid electrolyte premix obtained in step 4 is spread evenly in a polytetrafluoroethylene mold and solid electrolyte membrane is prepared under vacuum drying.

[0019] Step 9: Assemble the battery: In an argon-protected glove box, stack the positive electrode sheet → solid electrolyte membrane → platinum-carbon negative electrode sheet in that order, put them into the battery case, and press them with a tablet press to obtain an aqueous hydrogen solid secondary battery.

[0020] Preferably, the material pretreatment in step two includes:

[0021] S1.1. Vanadium source, potassium hexacyanoferrate and carboxylated carbon nanotubes were vacuum dried at 55-60℃ for 2-4 hours.

[0022] S1.2. After drying the clay in an oven at 75-80℃ for 4-6 hours, grind it through a 200-300 mesh sieve; place the platinum-carbon catalyst, conductive agent, and binder in a desiccator for later use;

[0023] S1.3. Cut the titanium mesh into circular pieces with a diameter of 19-21 mm, and ultrasonically clean them with 1 mol / L hydrochloric acid solution for 25-30 min, ultrasonically clean them with deionized water 2-3 times, and finally vacuum dry them at 55-60℃ for 1-2 h for later use.

[0024] Preferably, the solution preparation in step three is as follows:

[0025] S2.1 Preparation of vanadium source solution: Add the pretreated vanadium source to 74.95-75.05 mL of hydrochloric acid solution with a concentration of 5.95-6.05 mol / L, and stir magnetically in a constant temperature water bath at 45-50℃ for 1.5-2 h until the vanadium source is completely dissolved to form a clear vanadium source solution. After cooling to room temperature, seal and store.

[0026] S2.2 Preparation of potassium ferricyanide solution: Add the pretreated potassium hexacyanoferrate to 49.95-50.05 mL of deionized water and stir magnetically for 25-30 min at room temperature until completely dissolved to form a green and transparent potassium ferricyanide solution.

[0027] S2.3 Preparation of carbon nanotube dispersion: Add the pretreated carboxylated carbon nanotubes to 39.95-40.05 mL of deionized water and ultrasonically disperse at 300-350 W for 0.99-1 h to form a carbon nanotube dispersion.

[0028] Preferably, the vanadium source is one or both of vanadium oxysulfate and vanadium trichloride, and the chemical formula for the mixed reaction of the vanadium source solution and potassium ferricyanide solution is:

[0029] (1) When the vanadium source is vanadium oxysulfate:

[0030] VOSO4+K3[Fe(CN)6 KVO[Fe(CN)6]+K2SO4;

[0031] (2) When the vanadium source is vanadium trichloride:

[0032] VO 2+ +K3[Fe(CN)6+Cl - KVO[Fe(CN)6]+2KCl;

[0033] The reaction temperature in the above formula is 40-80℃, the reaction time is 7-12h, and magnetic stirring at a speed of 200-300r / min is required during the reaction.

[0034] Preferably, in step five, a hydrogen-modified vanadium ferrocyanide composite active material is prepared:

[0035] S3.1 Prepare vanadium source solution, potassium ferricyanide solution and deionized water according to the mass-volume ratio of 80-120mg:100-200mg:30-60mL;

[0036] S3.2. Take the vanadium source solution prepared in step two and add it to the carbon nanotube dispersion prepared in step four.

[0037] S3.3. Then, under continuous stirring at 250-300 r / min, add the potassium ferricyanide solution prepared in step 3 dropwise to the carbon nanotube dispersion. After the addition is complete, transfer to a constant temperature water bath at 55-60℃ for 9-10 h.

[0038] After the S3.4 and S3.3 reactions are completed, wash the product 2-3 times with deionized water and ethanol alternately, and centrifuge at 7000-8000 r / min for 13-15 min.

[0039] S3.5 Finally, vacuum dry at 55-60℃ for 4-6 hours to obtain hydrogen-modified vanadium ferrocyanide composite active material.

[0040] Preferably, step six involves preparing the positive electrode sheet:

[0041] S4.1 Mix the hydrogen-modified vanadium ferrocyanide composite active material, conductive agent, and binder in a mass ratio of 7:2:1;

[0042] S4.2 Add 20-30% ethanol of the total mass of the mixture, and stir continuously at 300-500 r / min for 2-4 hours at room temperature to prepare a paste.

[0043] S4.3. The obtained adhesive is uniformly coated onto the surface of the titanium mesh current collector. The coating thickness is controlled by a scraper to precisely control the active material loading at 1.057-1.059 mg·cm³. -2 Within the range;

[0044] S4.4 Finally, place the coated electrode in an oven at 55-60℃ for pre-drying. After the solvent has basically evaporated, it is ready for use.

[0045] Preferably, in step seven, the platinum-carbon negative electrode sheet is prepared by mixing platinum-carbon negative electrode catalyst powder and binder at a mass ratio of 4:1, adding 20-30% ethanol by mass to form a slurry, rolling the slurry onto a titanium mesh current collector to form a negative electrode sheet, and controlling the platinum loading to be 1-1.02 mg·cm³. -2 Vacuum dry at 55-60℃ for 3-4 hours for later use;

[0046] In step eight, a solid electrolyte membrane is prepared by spreading the solid electrolyte premix obtained in step four in a polytetrafluoroethylene mold and vacuum drying it at 55-60℃ for 1.5-2 hours to produce a solid electrolyte membrane with a thickness of 0.19-0.21 mm and a diameter of 19-21 mm.

[0047] An application of a long-cycle-life aqueous hydrogen solid-state secondary battery: The aqueous hydrogen solid-state secondary battery prepared according to the above method is applied to renewable energy storage systems, grid peak-shaving energy storage devices, and power supply systems for portable electronic devices.

[0048] Compared with the prior art, the present invention provides a long cycle life aqueous hydrogen solid-state secondary battery and its application, which has the following beneficial effects:

[0049] 1. This invention prepares hydrogen-modified vanadium ferrocyanide (H-VHCF) and uses it as a novel cathode material to achieve the beneficial effects of high specific capacity, excellent proton conductivity and stable crystal framework. This material uses the abundant vanadium element as its core, and its material procurement cost is low, which solves the problem of low specific capacity or limited resources of traditional cathode materials (such as nickel-based and Prussian blue analogues).

[0050] 2. This invention uses an acidic electrolyte-clay composite to prepare a solid electrolyte membrane, achieving the beneficial effects of both high ionic conductivity and excellent safety. The element-rich clay framework can not only effectively fix the electrolyte, suppress hydrogen evolution side reactions and dendrite growth, but also completely avoid the risk of leakage of liquid electrolyte, thereby improving the cycle life and safety of the battery.

[0051] 3. This invention achieves the beneficial effects of reducing interface impedance, ensuring efficient proton transport and stable cycling by precisely controlling the active material loading and using specific pressure encapsulation. This overall design enables the battery to achieve a long cycle life while maintaining the intrinsic safety of aqueous batteries. Attached Figure Description

[0052] Figure 1 This is a flowchart of the battery manufacturing process of the present invention;

[0053] Figure 2 This is a battery cycle performance diagram from Embodiment 1 of the present invention;

[0054] Figure 3 This is a battery performance curve diagram of Embodiment 1 of the present invention;

[0055] Figure 4 This is a cyclic stability diagram of the electrode material in Embodiment 1 of the present invention. Detailed Implementation

[0056] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0057] Please see Figures 1-4 A long-cycle-life aqueous hydrogen solid-state secondary battery comprises a hydrogen-modified vanadium iron cyanide composite (H-VHCF) cathode (50-60% by mass), a platinum-carbon (Pt / C) anode (10-15%), and a solid electrolyte (25-40%).

[0058] Specifically, the solid electrolyte includes an acidic electrolyte and clay, wherein the mass ratio of the acidic electrolyte to clay in the solid electrolyte is 0.5-1.5:1-5; the volume concentration of the acidic electrolyte is 10%-85%; the acidic electrolyte is selected from either phosphoric acid (H3PO4) or sulfuric acid (H2SO4); the clay is selected from two or three of magnesium silicate clay (Mg2H2(SiO3)3·3.0H2O), bentonite-type clay (H2Al2O6Si·1.19H2O), and kaolin-type aluminosilicate clay (H4Al2O9Si2·0.32H2O); and platinum in the platinum-carbon anode accounts for 15%-50% of the total mass of the platinum-carbon anode.

[0059] Specifically, the raw materials and their functions are as follows:

[0060] Table 1

[0061] Serial Number Raw material name Function Description 1 <![CDATA[Vanadyl sulfate (VOSO4)]]> As a vanadium source precursor, it is used to synthesize hydrogen-modified vanadium ferrocyanide composite active materials (HC-VHCF), providing vanadium to participate in electrochemical reactions. 2 <![CDATA[Vanadium(III) chloride (VCl3)]]> By replacing or supplementing vanadium sources, the crystal structure and electronic conductivity of materials can be controlled through combinations of vanadium compounds with different valence states. 3 <![CDATA[Potassium hexacyanoferrate (K3[Fe(CN)6])]]> The reaction with a vanadium source produces a vanadium ferrocyanide complex structure, providing ferrocyanide ligands to stabilize the crystal framework and enhance proton conductivity. 4 Carboxylated carbon nanotubes As a conductive additive and carrier matrix, it enhances the electronic conductivity and mechanical strength of composite materials. 5 <![CDATA[Phosphoric acid (H3PO4)]]> <![CDATA[As an acidic electrolyte, it provides a proton (H + ), a conduction medium, participates in electrode reactions, and optimizes interfacial charge transfer kinetics]]> 6 <![CDATA[Sulfuric acid (H2SO4)]]> Replacing phosphoric acid as an acidic electrolyte, it further improves battery rate performance through higher ionic conductivity. 7 <![CDATA[Magnesium silicate clay (Mg2H2(SiO3)3·3.0H2O)]]> As a solid electrolyte framework, it adsorbs electrolyte through its layered structure and suppresses side reactions, maintaining ion channels between electrodes. 8 <![CDATA[Bentonite clay (H2Al2O6Si·1.19H2O)]]> It provides high specific surface area and cation exchange capacity, enhancing electrolyte retention capacity and interfacial contact stability. 9 <![CDATA[Kaolin-type aluminosilicate clay (H4Al2O9Si2·0.32H2O)]]> Improve the mechanical strength and thermal stability of solid electrolytes and inhibit dendrite growth. 10 Platinum-carbon catalyst (Pt / C) As a negative electrode catalyst layer, it reduces the hydrogen evolution / hydrogen absorption overpotential and accelerates the hydrogen adsorption-dissociation kinetic equilibrium. 11 Acetylene black As a positive electrode conductive agent, a three-dimensional conductive network is constructed to improve the utilization rate of active materials. 12 Polytetrafluoroethylene (PTFE) emulsion As a binder, it fixes active materials and conductive agent particles, maintaining the integrity of the electrode structure. 13 Titanium mesh As a current collector, it provides an electron conduction pathway and supports the electrode material.

[0062] Specifically, a long-cycle-life aqueous hydrogen solid-state secondary battery includes the following steps:

[0063] Step 1: Material Preparation: Prepare vanadium source (analytical grade), potassium hexacyanoferrate (K3[Fe(CN)6], analytical grade), carboxylated carbon nanotubes (purity ≥98%), clay, platinum-carbon catalyst, conductive agent, binder, titanium mesh (purity ≥99.5%, thickness 0.1mm), polytetrafluoroethylene mold, acidic electrolyte, hydrochloric acid, ethanol, and deionized water;

[0064] Step 2, Material Pretreatment: The vanadium source, potassium hexacyanoferrate, carboxylated carbon nanotubes, clay, platinum-carbon catalyst, conductive agent, binder and titanium mesh are pretreated for later use.

[0065] Step 3, Solution preparation: Prepare vanadium source solution, potassium ferricyanide solution and carbon nanotube dispersion separately;

[0066] Step 4: Preparation of solid electrolyte premix: Add the pretreated bentonite and acidic electrolyte to an agate mortar according to the formula mass ratio and grind manually for 8-10 minutes. Then transfer to a planetary ball mill and ball mill at 180-200 r / min for 30-35 minutes to obtain a uniform solid electrolyte premix.

[0067] Step 5, Positive Electrode Active Material: Take the vanadium source solution prepared in Step 2 and add it to the carbon nanotube dispersion prepared in Step 4. Under continuous stirring, add the potassium ferricyanide solution prepared in Step 3 dropwise to the carbon nanotube dispersion. After the addition is completed, transfer it to a constant temperature water bath for mixing reaction. After the reaction is completed, wash, centrifuge and vacuum dry the mixed reaction product to finally obtain the hydrogen-modified vanadium ferricyanide composite active material.

[0068] Step 6: Preparation of positive electrode sheet: Mix hydrogen-modified vanadium iron cyanide composite active material, conductive agent and binder in a mass ratio, add ethanol to make a paste, and roll it on a titanium mesh current collector to make a positive electrode sheet;

[0069] Step 7: Preparation of platinum-carbon negative electrode sheet: Mix platinum-carbon negative electrode catalyst powder and binder according to the formula mass ratio, add ethanol to make a slurry, and roll it out on a titanium mesh current collector to make a negative electrode sheet.

[0070] Step 8: Preparation of solid electrolyte membrane: The solid electrolyte premix obtained in step 4 is spread evenly in a polytetrafluoroethylene mold and solid electrolyte membrane is prepared under vacuum drying.

[0071] Step 9: Assemble the battery: In an argon-protected glove box, stack the positive electrode sheet → solid electrolyte membrane → platinum-carbon negative electrode sheet in that order, put them into the battery case, and press them with a press at 4-5 MPa for 3-5 minutes to obtain an aqueous hydrogen solid secondary battery.

[0072] Specifically, in step two, the material pretreatment includes:

[0073] S1.1. Vanadium source, potassium hexacyanoferrate and carboxylated carbon nanotubes are vacuum dried at 55-60℃ for 2-4h to remove surface adsorbed water and prevent moisture from interfering with subsequent chemical reactions and degrading electrode performance.

[0074] S1.2 After drying the clay in an oven at 75-80℃ for 4-6 hours, grind it through a 200-300 mesh sieve; place the platinum-carbon catalyst, conductive agent, and binder (mass fraction 55-60%) in a desiccator for later use to ensure the uniformity and density of the solid electrolyte membrane preparation.

[0075] S1.3. Titanium mesh (purity ≥99.5%, thickness 0.1-0.12mm) is cut into circular pieces with a diameter of 19-21mm. It is then ultrasonically cleaned with 1mol / L hydrochloric acid solution for 25-30min, followed by ultrasonic cleaning with deionized water 2-3 times (13-15min each time). Finally, it is vacuum dried at 55-60℃ for 1-2h for later use to thoroughly remove surface oxides and contaminants, and enhance its bonding force with active materials and the reliability of conductive contact.

[0076] Specifically, in step three, the solution is prepared as follows:

[0077] S2.1 Preparation of vanadium source solution: Weigh 3.98-4.02g of pretreated vanadium source and slowly add it to 74.95-75.05mL of hydrochloric acid (HCl) solution with a concentration of 5.95-6.05mol / L. Stir magnetically in a constant temperature water bath at 45-50℃ for 1.5-2h until the vanadium source is completely dissolved and a clear vanadium source solution is formed. After cooling to room temperature, seal and store. The constant temperature water bath can ensure the stability and high reactivity of the vanadium precursor solution.

[0078] S2.2 Preparation of potassium ferricyanide solution: Weigh 1.1845-1.1855g of pretreated potassium hexacyanoferrate and add it to 49.95-50.05mL of deionized water. Stir magnetically at room temperature for 25-30min until completely dissolved to form a green and transparent potassium ferricyanide solution.

[0079] S2.3 Preparation of carbon nanotube dispersion: Weigh 0.0495-0.505g of pretreated carboxylated carbon nanotubes and add them to 39.95-40.05mL of deionized water. Disperse the dispersion by ultrasonication at 300-350W power for 0.99-1h to form a uniform and stable carbon nanotube dispersion. Ultrasonic dispersion enables the effective construction of a conductive network in the composite material.

[0080] Specifically, step five involves the preparation of hydrogen-modified vanadium ferrocyanide composite active materials:

[0081] S3.1 Prepare vanadium source solution, potassium ferricyanide solution and deionized water according to the mass-volume ratio of 80-120mg:100-200mg:30-60mL;

[0082] S3.2. Take the vanadium source solution prepared in step two and add it to the carbon nanotube dispersion prepared in step four.

[0083] S3.3. Then, under continuous stirring at 250-300 r / min, add the potassium ferricyanide solution prepared in step 3 dropwise to the carbon nanotube dispersion. After the addition is complete, transfer to a constant temperature water bath at 55-60℃ for 9-10 h.

[0084] After the S3.4 and S3.3 reactions are completed, wash the product 2-3 times with deionized water and ethanol alternately, and centrifuge at 7000-8000 r / min for 13-15 min.

[0085] S3.5 Finally, vacuum dry at 55-60℃ for 4-6 hours to obtain hydrogen-modified vanadium ferrocyanide composite active material.

[0086] The advantages are: by controlling the reactant ratio, dropping rate, reaction temperature and time, uniform growth and composite of vanadium ferrocyanide on carbon nanotubes can be achieved, ultimately forming a stable nanostructure.

[0087] Specifically, the vanadium source is one or both of vanadium oxysulfate (VOSO4) or vanadium trichloride (VCl3) (when the vanadium source is vanadium oxysulfate (VOSO4), it is directly dissolved in deionized water to form a vanadium source solution without the need for additional acid solution). The chemical formula for the reaction of the vanadium source solution and potassium ferricyanide solution is:

[0088] (1) When the vanadium source is vanadium oxysulfate (VOSO4):

[0089] VOSO4+K3[Fe(CN)6 KVO[Fe(CN)6]+K2SO4;

[0090] (2) When the vanadium source is vanadium trichloride (VCl3), it dissociates into VO under acidic conditions. 2+ )hour:

[0091] VO 2+ +K3[Fe(CN)6+Cl - KVO[Fe(CN)6]+2KCl;

[0092] The reaction temperature in the above formula is 40-80℃, and the reaction time is 7-12h. During the reaction, the stirring speed should be maintained at 200-300r / min with magnetic stirring to ensure that the reaction system is uniformly mixed and to avoid excessive local concentration that may lead to product agglomeration.

[0093] Specifically, step six involves preparing the positive electrode sheet:

[0094] S4.1 Mix the hydrogen-modified vanadium ferrocyanide composite active material, conductive agent, and binder in a mass ratio of 7:2:1;

[0095] S4.2 Add 20-30% ethanol of the total mass of the mixture, and stir continuously at 300-500 r / min for 2-4 hours at room temperature to prepare a paste.

[0096] S4.3. The obtained adhesive is uniformly coated onto the surface of the titanium mesh current collector. The coating thickness is controlled by a scraper to precisely control the active material loading at 1.057-1.059 mg·cm³. -2 Within the range;

[0097] S4.4 Finally, place the coated electrode in an oven at 55-60℃ for pre-drying. After the solvent has basically evaporated, it is ready for use.

[0098] Specifically, in step seven, the platinum-carbon negative electrode sheet is prepared by mixing platinum-carbon negative electrode catalyst powder and binder at a mass ratio of 4:1, adding 20-30% ethanol by mass to form a slurry, rolling it onto a titanium mesh current collector to form the negative electrode sheet, and controlling the platinum (Pt) loading to be 1-1.02 mg·cm³. -2 Vacuum dry at 55-60℃ for 3-4 hours for later use;

[0099] Specifically, in step eight, a solid electrolyte membrane is prepared by spreading the solid electrolyte premix obtained in step four in a polytetrafluoroethylene mold and vacuum drying it at 55-60℃ for 1.5-2 hours to produce a solid electrolyte membrane with a thickness of 0.19-0.21 mm and a diameter of 19-21 mm.

[0100] The advantage is that by vacuum drying at a specific temperature, the gel premix is ​​cured to form a dense solid film with microscopic ion channels.

[0101] An application of a long-cycle-life aqueous hydrogen solid-state secondary battery: The aqueous hydrogen solid-state secondary battery prepared according to the above method is applied to renewable energy storage systems, grid peak-shaving energy storage devices, and power supply systems for portable electronic devices.

[0102] Examples 1-3 were prepared using the battery preparation method of the present invention, referring to comparative examples 1-3, specifically as follows:

[0103] Example 1

[0104] S1. Preparation of HCVHCF cathode: 4 g of vanadium source was added to 75 ml of HCl and stirred. 9.4 ml of the solution was added to 40 ml of carbon nanotube dispersion and labeled as A. 3.6 mmol of K3[Fe(CN)6] was added to 50 mL of deionized water to form a green solution labeled as B. Then, B was slowly added dropwise to solution A under continuous stirring. The reaction was carried out at 60 °C for 9 h. After washing, centrifugation, and drying, the HC-VHCF cathode was obtained.

[0105] S2. Preparation of positive electrode sheet, Pt / C negative electrode sheet and solid electrolyte membrane:

[0106] (1) The preparation method of the positive electrode sheet is as follows: the positive active material H-VHCF, the conductive agent acetylene black and the binder PTFE are rolled into a film in a ratio of 7:2:1 to form an electrode, wherein the current collector is a titanium mesh and the loading of the active material is 1.058 mg·cm³. -2 The diameter of the positive electrode is 19mm;

[0107] (2) The preparation method of Pt / C negative electrode sheet is as follows: Pt / C negative electrode catalyst powder and binder PTFE are rolled into film in a ratio of 8:2 to form an electrode, wherein the current collector is a titanium mesh and the Pt loading is 1 mg·cm³. -2 The diameter of the Pt / C negative electrode sheet is 19 mm; Pt accounts for 40% of the total mass of the Pt / C negative electrode.

[0108] (3) The solid electrolyte membrane is prepared by mixing bentonite H2Al2O6Si·1.19H2O with acidic electrolyte H3PO4 at a mass ratio of 1:1 to form a gel-like solid electrolyte membrane, wherein the concentration of acidic electrolyte H3PO4 is 63%;

[0109] S4. Finally, assemble the battery. The assembly order of the battery is: positive electrode, solid electrolyte membrane and Pt / C negative electrode.

[0110] The charging and discharging principle of the hydrogen solid-state secondary battery with vanadium-based cathode assembled in Example 1 is as follows: Figure 1 As shown, during the first charge, the positive electrode material HC-VHCF releases H... + In the solid electrolyte membrane, protons react to generate hydrogen gas under the catalysis of the negative electrode catalyst Pt. During the discharge process, hydrogen gas reacts on the negative electrode catalyst Pt to generate protons, which are then transferred to the solid electrolyte and inserted into the positive electrode material through the Grotthuss mechanism to generate H-VHCF. In the second and subsequent charge and discharge processes, the positive electrode is characterized by the insertion of protons into C-VHCF (discharge process) and the extraction of protons from HC-VHCF (charge process), while the negative electrode is characterized by the oxidation and reduction reactions of protons.

[0111] Example 2

[0112] S1. Preparation of HCVHCF cathode: Dissolve 4g VOSO4 in 75ml deionized water and stir. Take 9.4ml of the solution and add it to 40ml carbon nanotube dispersion, which is recorded as A. Then add 3.6mmol K3[Fe(CN)6] to 50mL deionized water to form a green solution, which is recorded as B. Then, under continuous stirring, slowly add B to solution A. React at 60℃ for 9h. Wash, centrifuge and dry to obtain the cathode HC-VHCF.

[0113] S2. Preparation of positive electrode, Pt / C negative electrode and solid electrolyte membrane: (The method is the same as in Example 1, but the clay in the solid electrolyte membrane is a 1:1 mixture of sepiolite and bentonite, the acidic electrolyte is 50% H2SO4, and the clay / acid mass ratio is 1.5:1).

[0114] Example 3

[0115] S1. Preparation of HCVHCF cathode: (Method is the same as in Example 1, vanadium source is VCl3);

[0116] S2. Preparation of positive electrode sheet, Pt / C negative electrode sheet and solid electrolyte membrane: (The method is the same as in Example 1, but the clay in the solid electrolyte membrane is a mixture of three types of clay in equal proportions, and the clay / acid mass ratio is 1:2).

[0117] Comparative Example 1

[0118] A commercial Mn-based Prussian blue analogue was used instead of H-VHCF as the cathode material, and the remaining steps were exactly the same as in Example 1.

[0119] Comparative Example 2

[0120] The battery was assembled using a liquid 63% H3PO4 electrolyte (clay-free skeleton) and a glass fiber separator, and the remaining steps were exactly the same as in Example 2.

[0121] Comparative Example 3

[0122] The negative electrode uses pure carbon material without Pt catalyst, and the remaining steps are exactly the same as in Example 3.

[0123] The performance test results are shown in Table 2 below:

[0124] Table 2

[0125] Test Project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Initial discharge capacity (mAh / g) 320 315 318 280 275 260 Capacity retention rate (%) after 500 cycles 92.3 91.5 90.8 78.6 65.4 55.2 Capacity retention (%) at 10C rate 85.2 84.7 83.9 68.4 52.1 40.3 -20℃ low-temperature discharge capacity (mAh / g) 245 240 238 205 180 165 Charge / discharge efficiency (%) 94.5 93.8 93.2 91.2 88.7 85.5 Cycle life (times) >5000 >4800 >4500 3200 2100 1800

[0126] Table 2 summarizes the following:

[0127] The batteries in Examples 1-3 exhibit significant advantages in cycle life, rate performance, and low-temperature performance, specifically in the following three aspects:

[0128] 1. Excellent cycle stability: After 500 cycles, the capacity retention rate of Examples 1-3 was all above 90%, which was far better than that of Comparative Example 1 (78.6%), Comparative Example 2 (65.4%) and Comparative Example 3 (55.2%). This is due to the stable reversible proton insertion / extraction capability of H-VHCF cathode material, the effective suppression of interfacial side reactions by clay components in solid electrolyte, and the electrode interface stability maintained by efficient catalysis of Pt / C anode. The synergistic effect of these three factors ensures the long cycle life of the batteries in the examples.

[0129] 2. Excellent high-rate performance: The capacity retention rate of the battery in the example is still over 83% at a high rate of 10C, while that of the comparative example is generally less than 70%. This is mainly due to the continuous proton conduction channel constructed by the acidic electrolyte-clay in the example, combined with the intrinsic fast ion diffusion characteristics of the H-VHCF cathode material, which together realize the high-speed migration of protons in the battery, thereby improving its rate performance.

[0130] 3. Excellent low-temperature performance: The discharge capacity of the embodiment at -20℃ remains at 238-245mAh / g, which is significantly higher than that of the comparative example (165-205mAh / g). This is due to the gelation design of the solid electrolyte in the embodiment battery, which can effectively reduce the risk of electrolyte solidification at low temperatures. At the same time, the crystal structure of the H-VHCF cathode material can remain stable at low temperatures, thereby ensuring the smooth ion transport path and enabling the battery to maintain a high capacity output in low-temperature environments.

[0131] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A long-cycle-life aqueous hydrogen solid-state secondary battery, characterized in that, It includes a hydrogen-modified vanadium ferrocyanide composite cathode (50-60% by mass), a platinum-carbon anode (10-15% by mass), and a solid electrolyte (25-40% by mass).

2. The long-cycle-life aqueous hydrogen solid-state secondary battery according to claim 1, characterized in that, The solid electrolyte comprises an acidic electrolyte and clay, wherein the mass ratio of the acidic electrolyte to clay in the solid electrolyte is 0.5-1.5:1-5; the volume concentration of the acidic electrolyte is 10%-85%; the acidic electrolyte is selected from phosphoric acid or sulfuric acid; the clay is selected from two or three of magnesium-based silicate clay, bentonite-type clay, and kaolin-type aluminosilicate clay; and platinum accounts for 15%-50% of the total mass of the platinum-carbon anode.

3. The long-cycle-life aqueous hydrogen solid-state secondary battery according to claim 1, characterized in that, Includes the following steps: Step 1: Material preparation: Prepare vanadium source, potassium hexacyanoferrate, carboxylated carbon nanotubes, clay, platinum carbon catalyst, conductive agent, binder, titanium mesh, polytetrafluoroethylene mold, acidic electrolyte, hydrochloric acid, ethanol and deionized water. Step 2, Material Pretreatment: The vanadium source, potassium hexacyanoferrate, carboxylated carbon nanotubes, clay, platinum-carbon catalyst, conductive agent, binder and titanium mesh are pretreated for later use. Step 3, Solution preparation: Prepare vanadium source solution, potassium ferricyanide solution and carbon nanotube dispersion separately; Step 4: Preparation of solid electrolyte premix: The pretreated bentonite and acidic electrolyte are added to an agate mortar and manually ground according to the formula mass ratio, and then transferred to a planetary ball mill for ball milling to obtain solid electrolyte premix. Step 5, Positive Electrode Active Material: Take the vanadium source solution prepared in Step 2 and add it to the carbon nanotube dispersion prepared in Step 4. Under continuous stirring, add the potassium ferricyanide solution from Step 3 dropwise to the carbon nanotube dispersion. Mix and react in a constant temperature water bath. Wash, centrifuge and vacuum dry the mixed reaction product to obtain hydrogen-modified vanadium ferricyanide composite active material. Step 6: Preparation of positive electrode sheet: Mix hydrogen-modified vanadium iron cyanide composite active material, conductive agent and binder in a mass ratio, add ethanol to make a paste, and roll it on a titanium mesh current collector to make a positive electrode sheet; Step 7: Preparation of platinum-carbon negative electrode sheet: Mix platinum-carbon negative electrode catalyst powder and binder according to the formula mass ratio, add ethanol to make a slurry, and roll it out on a titanium mesh current collector to make a negative electrode sheet. Step 8: Preparation of solid electrolyte membrane: The solid electrolyte premix obtained in step 4 is spread evenly in a polytetrafluoroethylene mold and solid electrolyte membrane is prepared under vacuum drying. Step 9: Assemble the battery: In an argon-protected glove box, stack the positive electrode sheet → solid electrolyte membrane → platinum-carbon negative electrode sheet in that order, put them into the battery case, and press them with a tablet press to obtain an aqueous hydrogen solid secondary battery.

4. The long-cycle-life aqueous hydrogen solid-state secondary battery according to claim 3, characterized in that, The material pretreatment in step two: S1.

1. Vanadium source, potassium hexacyanoferrate and carboxylated carbon nanotubes were vacuum dried at 55-60℃ for 2-4 hours. S1.

2. After drying the clay in an oven at 75-80℃ for 4-6 hours, grind it through a 200-300 mesh sieve; place the platinum-carbon catalyst, conductive agent, and binder in a desiccator for later use. S1.

3. Cut the titanium mesh into circular pieces with a diameter of 19-21 mm, and ultrasonically clean them with 1 mol / L hydrochloric acid solution for 25-30 min, ultrasonically clean them with deionized water 2-3 times, and finally vacuum dry them at 55-60℃ for 1-2 h for later use.

5. A long-cycle-life aqueous hydrogen solid-state secondary battery according to claim 3, characterized in that, Solution preparation in step three: S2.1 Preparation of vanadium source solution: Add the pretreated vanadium source to 74.95-75.05 mL of hydrochloric acid solution with a concentration of 5.95-6.05 mol / L, and stir magnetically in a constant temperature water bath at 45-50℃ for 1.5-2 h until the vanadium source is completely dissolved to form a clear vanadium source solution. After cooling to room temperature, seal and store. S2.2 Preparation of potassium ferricyanide solution: Add the pretreated potassium hexacyanoferrate to 49.95-50.05 mL of deionized water and stir magnetically for 25-30 min at room temperature until completely dissolved to form a green and transparent potassium ferricyanide solution. S2.3 Preparation of carbon nanotube dispersion: Add the pretreated carboxylated carbon nanotubes to 39.95-40.05 mL of deionized water and ultrasonically disperse at 300-350 W for 0.99-1 h to form a carbon nanotube dispersion.

6. The long-cycle-life aqueous hydrogen solid-state secondary battery according to claim 5, characterized in that, The vanadium source is one or both of vanadium oxysulfate and vanadium trichloride. The chemical formula for the mixed reaction of the vanadium source solution and potassium ferricyanide solution is: (1) When the vanadium source is vanadium oxysulfate: VOSO4+K3[Fe(CN)6 KVO[Fe(CN)6]+K2SO4; (2) When the vanadium source is vanadium trichloride: VO 2+ +K3[Fe(CN)6+Cl - KVO[Fe(CN)6]+2KCl; The reaction temperature in the above formula is 40-80℃, the reaction time is 7-12h, and magnetic stirring at a speed of 200-300r / min is required during the reaction.

7. A long-cycle-life aqueous hydrogen solid-state secondary battery according to claim 3, characterized in that, In step five, hydrogen-modified vanadium ferrocyanide composite active materials are prepared: S3.1 Prepare vanadium source solution, potassium ferricyanide solution and deionized water according to the mass-volume ratio of 80-120mg:100-200mg:30-60mL; S3.

2. Take the vanadium source solution prepared in step two and add it to the carbon nanotube dispersion prepared in step four. S3.

3. Then, under continuous stirring at 250-300 r / min, add the potassium ferricyanide solution prepared in step 3 dropwise to the carbon nanotube dispersion. After the addition is complete, transfer to a constant temperature water bath at 55-60℃ for 9-10 h. After the S3.4 and S3.3 reactions are completed, wash the product 2-3 times with deionized water and ethanol alternately, and centrifuge at 7000-8000 r / min for 13-15 min. S3.5 Finally, vacuum dry at 55-60℃ for 4-6 hours to obtain hydrogen-modified vanadium ferrocyanide composite active material.

8. A long-cycle-life aqueous hydrogen solid-state secondary battery according to claim 3, characterized in that, Step six involves preparing the positive electrode sheet: S4.1 Mix the hydrogen-modified vanadium ferrocyanide composite active material, conductive agent, and binder in a mass ratio of 7:2:1; S4.2 Add 20-30% ethanol of the total mass of the mixture, and stir continuously at 300-500 r / min for 2-4 hours at room temperature to prepare a paste. S4.

3. The obtained adhesive is uniformly coated onto the surface of the titanium mesh current collector. The coating thickness is controlled by a scraper to precisely control the active material loading at 1.057-1.059 mg·cm³. -2 Within the range; S4.4 Finally, place the coated electrode in an oven at 55-60℃ for pre-drying. After the solvent has basically evaporated, it is ready for use.

9. A long-cycle-life aqueous hydrogen solid-state secondary battery according to claim 3, characterized in that, In step seven, the platinum-carbon negative electrode sheet is prepared by mixing platinum-carbon negative electrode catalyst powder and binder at a mass ratio of 4:1, adding 20-30% ethanol to form a slurry, rolling the slurry onto a titanium mesh current collector to form the negative electrode sheet, and controlling the platinum loading to be 1-1.02 mg·cm³. -2 Vacuum dry at 55-60℃ for 3-4 hours for later use; In step eight, a solid electrolyte membrane is prepared by spreading the solid electrolyte premix obtained in step four in a polytetrafluoroethylene mold and vacuum drying it at 55-60℃ for 1.5-2 hours to produce a solid electrolyte membrane with a thickness of 0.19-0.21 mm and a diameter of 19-21 mm.

10. An application of a long-cycle-life aqueous hydrogen solid-state secondary battery, characterized in that, The aqueous hydrogen solid-state secondary battery prepared according to claim 3 can be applied to renewable energy storage systems, grid peak-shaving energy storage devices, and portable electronic device power supply systems.

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