Composite positive electrode material and preparation method and application thereof

Abstract

The application relates to the technical field of batteries, in particular to a composite positive electrode material and a preparation method and application thereof. The composite positive electrode material comprises a positive electrode matrix and a coating layer coated on the surface of the positive electrode matrix, the positive electrode matrix comprises a core material and a carbon material layer coated on the surface of the core material, the core material comprises a lithium manganese iron phosphate material and a doping element M, the doping element M comprises at least one of vanadium, titanium, niobium and magnesium, and the coating layer comprises titanium nitride. The composite positive electrode material provided by the application can slow down the dissolution of Mn in the lithium manganese iron phosphate material, and the cooperation with the materials of the layers of the positive electrode matrix can improve the cycle stability. The battery provided by the application adopts the composite positive electrode material and an electrolyte, Li + / Zn 2+ double carriers, so that the battery has higher energy density and a voltage window.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a composite positive electrode material and a preparation method and application thereof. BACKGROUND

[0002] At present, lithium ion batteries (LIBs) are widely used in new energy markets, such as electric vehicles, electric tools and scene energy storage. LIBs have high voltage windows and energy densities. However, the lithium battery electrolyte is a combustible organic solvent, which is prone to thermal runaway in the event of a safety accident. In recent years, there have been many reports of self-ignition of electric vehicles and electric energy storage boxes. Therefore, high-safety energy storage systems have received increasing attention. Water-based zinc ion batteries rely on the ultra-high safety of the water-based electrolyte system. Compared with non-aqueous systems, water-based batteries use water as a solvent, which has low volatility, non-toxicity and non-flammability. At the same time, the water-based electrolyte has high ionic conductivity, does not require a dry environment for assembly, and has unique advantages such as high power, fast charging and low manufacturing cost. The ultra-low raw material cost of metal zinc and the good service life are gradually becoming a research hotspot in the current large-scale energy storage field.

[0003] The negative electrode material of the traditional lithium ion battery is usually graphite, and the positive electrode is composed of lithium-containing transition metal oxides. During charging, lithium ions are stripped from the positive electrode and intercalated into the graphite negative electrode interlayer through the electrolyte, thereby converting electrical energy into chemical energy. During discharging, lithium ions are stripped from the graphite negative electrode and return to the positive electrode, thereby converting chemical energy into electrical energy. Unlike LIBs, traditional water-based zinc ion batteries use vanadium oxide as a positive electrode material and zinc metal as a negative electrode for zinc ion deposition. During discharging, zinc ions are stripped from the surface of the metal zinc and undergo a reduction reaction at the positive electrode to form zinc vanadium oxide. During charging, the reaction path is reversed, and zinc ions are stripped from the positive electrode and deposited on the metal zinc sheet. However, the types of positive electrode materials for current water-based zinc ion batteries are relatively few, especially vanadium oxide materials, which have certain limitations due to intrinsic toxicity and are difficult to produce and use on a large scale in industrial production.

[0004] In view of the above, the present application is proposed. SUMMARY

[0005] One object of the present application is to provide a composite positive electrode material. The titanium nitride coating layer can slow down the dissolution of Mn in the lithium manganese iron phosphate material, coordinate with the positive electrode matrix, and improve the cycle stability.

[0006] Another object of the present application is to provide a preparation method of the composite positive electrode material. The method is simple and easy to implement, and the cycle stability of the obtained composite positive electrode material is good.

[0007] Another object of the present application is to provide a positive electrode sheet.

[0008] Another object of the present application is to provide a water-based zinc ion battery.

[0009] In order to achieve the above object of the present application, the technical scheme is adopted as follows:

[0010] A composite positive electrode material comprises a positive electrode substrate and a coating layer coated on the surface of the positive electrode substrate, the positive electrode substrate comprises a core material and a carbon material layer coated on the surface of the core material, the core material comprises a lithium manganese iron phosphate material and a doping element M, the doping element M comprises at least one of vanadium, titanium, niobium and magnesium, and the coating layer comprises titanium nitride.

[0011] In some embodiments, the mass of the coating layer is 2% to 20% of the mass of the composite positive electrode material.

[0012] The preparation method of the composite positive electrode material as described above comprises the following steps:

[0013] Anhydrous ferrous manganese phosphate, a lithium source, a carbon source, a doping agent containing element M and a solvent are mixed and treated, and then ground to obtain a first material; a dispersion liquid of titanium nitride is mixed and stirred with the first material, and then dried and calcined.

[0014] In some embodiments, the mass ratio of the anhydrous ferrous manganese phosphate, the lithium source, the carbon source, the doping agent containing element M and the solvent is (300-600):(200-350):(120-200):(4-8):(1800-2500).

[0015] In some embodiments, the carbon source comprises at least one of starch, sucrose, fructose, maltose, cyclodextrin, citric acid and polyol materials.

[0016] In some embodiments, the doping agent containing element M comprises at least one of ammonium metavanadate, titanium dioxide, ammonium metavanadate, di vanadium pentoxide, di niobium pentoxide, anhydrous magnesium acetate and magnesium oxide.

[0017] In some embodiments, the lithium source comprises lithium phosphate.

[0018] In some embodiments, the anhydrous ferrous manganese phosphate is obtained by heat treatment of a ferrous manganese phosphate precursor; the temperature of the heat treatment is 500-600°C, and the time of the heat treatment is 4-6h.

[0019] In some embodiments, the rotation speed of the mixing treatment is 200-600rpm, and the time of the mixing treatment is 10-30min.

[0020] In some embodiments, the mass of the titanium nitride is 1% to 30% of the mass of the first material.

[0021] In some embodiments, the solid content of the titanium nitride in the dispersion is 5-30%.

[0022] In some embodiments, the preparation of the dispersion of titanium nitride comprises: subjecting the mixture of titanium nitride and water to high-pressure microjet treatment, wherein the pressure of the high-pressure microjet treatment is 10,000-22,000 psi, the flow rate of the high-pressure microjet treatment is 20-250 mL / min, and the time of the high-pressure microjet treatment is 30-60 min.

[0023] In some embodiments, the rotation speed of the mixing and stirring is 300-600 rpm, and the time of the mixing and stirring is 30-70 min.

[0024] In some embodiments, the drying is spray drying, wherein the inlet air temperature of the spray drying is 150-250℃, the pressure of the spray drying is 0.1-0.3 MPa, and the feeding speed of the spray drying is 10-30 rpm.

[0025] In some embodiments, the calcination comprises a first constant temperature treatment and a second constant temperature treatment, wherein the temperature of the first constant temperature treatment is 150-250℃, the time of the first constant temperature treatment is 3-6 h, the temperature of the second constant temperature treatment is 300-600℃, and the time of the second constant temperature treatment is 10-15 h.

[0026] An anode sheet comprising the composite anode material as described above, or prepared by the method for preparing a composite anode material as described above.

[0027] An aqueous zinc ion battery comprising the anode sheet as described above.

[0028] In some embodiments, the battery further comprises an electrolyte, wherein the electrolyte comprises a soluble zinc salt, a soluble lithium salt, and water, the soluble zinc salt comprises ZnSO4·7H2O, the soluble lithium salt comprises Li2SO4, the concentration of the soluble zinc salt is 0.7-1.2 mol / L, and the concentration of the soluble lithium is 0.2-0.5 mol / L.

[0029] In some embodiments, the method comprises: mixing a soluble zinc salt, a soluble lithium salt, and water, wherein the rotation speed of the mixing is 100-300 rpm, and the time of the mixing is 10-30 min.

[0030] An electrical equipment comprising the aqueous zinc ion battery as described above.

[0031] Compared with the prior art, the present application has the following beneficial effects:

[0032] (1) The composite positive electrode material of the present application, the doping element M in the positive electrode matrix can enhance the stability of the lithium manganese iron phosphate material, the carbon material layer can further improve the conductivity, the titanium nitride coating layer can slow down the dissolution of Mn in the lithium manganese iron phosphate material, and through the coordination of each layer, the cycle stability can be improved.

[0033] (2) The preparation method of the composite positive electrode material of the present application is simple and easy to operate, and through the cooperation of each step, a composite positive electrode material with stable structure and high capacity can be obtained.

[0034] (3) The battery of the present application adopts a composite positive electrode material to match the electrolyte, Li + / Zn 2+ double carriers, so that it has higher energy density and voltage window. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the specific embodiments or the prior art description will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0036] Figure 1 The scanning electron microscope image of the composite positive electrode material of the present application. DETAILED DESCRIPTION

[0037] The embodiments of the present application will be described in detail below with reference to the examples, but those skilled in the art will understand that the following examples are only used to illustrate the present application, and should not be regarded as limiting the scope of the present application. The specific conditions are not indicated in the examples, and the conventional conditions or the conditions recommended by the manufacturer are used. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products that can be obtained by purchase.

[0038] According to one aspect of the present application, the present application relates to a composite positive electrode material, comprising a positive electrode matrix and a coating layer coated on the surface of the positive electrode matrix, the positive electrode matrix comprising a core material and a carbon material layer coated on the surface of the core material, the core material comprising a lithium manganese iron phosphate material and a doping element M, the doping element M comprising at least one of vanadium, titanium, niobium and magnesium, and the coating layer comprising titanium nitride (TiN).

[0039] The composite positive electrode material of the present application, the doping element M in the positive electrode matrix can enhance the stability of the lithium manganese iron phosphate material, the carbon material layer can further improve the conductivity, the titanium nitride coating layer can slow down the dissolution of Mn in the lithium manganese iron phosphate material, and through the coordination of each layer, the cycle stability can be improved.

[0040] In some embodiments, the lithium manganese iron phosphate material is LiFe 0.4 Mn 0.6 PO4.

[0041] In some embodiments, the mass of the coating layer is 2% to 20% of the mass of the composite cathode material, for example, 2%, 3%, 5%, 6%, 8%, 10%, 12%, 15%, 18%, 20%, etc. The coating layer of the application has a suitable mass, which is more conducive to ensuring the electrochemical performance of the composite cathode material.

[0042] In some embodiments, the mass of the doping element M is 0.01% to 0.1% of the mass of the composite cathode material, for example, 0.01%, 0.02%, 0.05%, 0.06%, 0.08%, 0.1%, etc.

[0043] According to another aspect of the application, the application also relates to a preparation method of a composite cathode material, comprising the following steps:

[0044] The anhydrous ferrous manganese phosphate, the lithium source, the carbon source, the doping agent containing the element M, and the solvent are mixed and treated, and ground to obtain a first material; a dispersion liquid of titanium nitride is mixed and stirred with the first material, and then dried and calcined.

[0045] The preparation method of the composite cathode material of the application is simple and easy to implement, and through the cooperation of various steps, a composite cathode material with stable structure and high capacity can be obtained.

[0046] In some embodiments, the mass ratio of the anhydrous ferrous manganese phosphate, the lithium source, the carbon source, the doping agent containing the element M, and the solvent is (300-600):(200-350):(120-200):(4-8):(1800-2500), for example, 300:200:120:4:1800, 400:250:150:5:1900, 500:300:160:6:2000, 600:200:200:8:2300, etc. The various materials of the application adopt a suitable ratio, which is more conducive to the reaction.

[0047] In some embodiments, the carbon source includes at least one of starch, sucrose, fructose, maltose, cyclodextrin, citric acid, and polyalcohol material. The carbon source can improve the conductivity of the cathode material. The polyalcohol material includes at least one of polyethylene glycol, polyvinyl alcohol, and polyglycerol. In some embodiments, the carbon source includes starch and polyalcohol material, and the mass ratio of the starch and the polyalcohol material is (1-2):1, for example, 1:1, 1.5:1, 2:1, etc. The combination of the two is more conducive to improving the stability of the matrix material and improving the cycle performance of the final composite cathode material.

[0048] In some embodiments, the dopant containing element M includes at least one of ammonium metavanadate, titanium dioxide, ammonium metavanadate, vanadium pentoxide, niobium pentoxide, anhydrous magnesium acetate, and magnesium oxide.

[0049] In some embodiments, the lithium source includes lithium phosphate.

[0050] In some embodiments, the anhydrous ferrous manganese phosphate is derived from the ferrous manganese phosphate precursor (Mn 0.6 Fe 0.4 )3(PO4)2·6H2O is obtained by heat treatment; the temperature of the heat treatment is 500-600℃, for example 500℃, 520℃, 550℃, 580℃ or 600℃, etc., and the time of the heat treatment is 4-6h, for example 4h, 4.5h, 5h, 5.5h or 6h, etc.

[0051] In some embodiments, the mixing speed is 200–600 rpm, for example 200 rpm, 250 rpm, 300 rpm, 400 rpm, 500 rpm, or 600 rpm, and the mixing time is 10–30 min, for example 10 min, 15 min, 20 min, 25 min, or 30 min. The present invention employs suitable mixing and stirring conditions to ensure that the materials are thoroughly mixed.

[0052] In some embodiments, the mass of titanium nitride is 1% to 30% of the mass of the first material, for example, 1%, 2%, 5%, 6%, 8%, 10%, 12%, 15%, 18%, 20%, 25%, or 30%.

[0053] In some embodiments, the solid content of titanium nitride in the dispersion is 5% to 30%, for example, 5%, 8%, 10%, 15%, 20%, 25% or 30%.

[0054] In some embodiments, the preparation of the titanium nitride dispersion specifically includes: subjecting a mixture of titanium nitride and water to high-pressure microfluidic treatment; the pressure of the high-pressure microfluidic treatment is 10,000–22,000 psi, for example, 10,000 psi, 12,000 psi, 15,000 psi, 18,000 psi, 20,000 psi, 22,000 psi, etc.; the flow rate of the high-pressure microfluidic treatment is 20–250 mL / min, for example, 10 mL / min, 20 mL / min, 30 mL / min, 50 mL / min, 80 mL / min, or 100 mL / min, etc.; and the time of the high-pressure microfluidic treatment is 30–60 min, for example, 30 min, 40 min, 50 min, or 60 min, etc. By employing suitable high-pressure microfluidic treatment conditions, this invention can obtain a more uniformly dispersed titanium nitride dispersion, which is beneficial for subsequent coating layer preparation and improves the overall electrochemical performance of the composite cathode material.

[0055] In some embodiments, the mixing and stirring speed is 300–600 rpm, such as 300 rpm, 350 rpm, 400 rpm, 500 rpm, 600 rpm, etc. The mixing and stirring time is 30–70 min, such as 30 min, 40 min, 50 min, 60 min, etc. The present invention employs suitable mixing and stirring conditions to ensure that the titanium nitride dispersion is fully mixed with the first material, thus guaranteeing the subsequent coating effect.

[0056] In some embodiments, the drying is carried out by spray drying, the inlet air temperature of the spray drying is 150-250°C, for example 150°C, 160°C, 180°C, 200°C, 250°C, etc., the spray drying pressure is 0.1-0.3 MPa, for example 0.1 MPa, 0.2 MPa, 0.3 MPa, etc., and the feed rate of the spray drying is 10-30 rpm, for example 10 rpm, 20 rpm, or 30 rpm, etc.

[0057] In some embodiments, the calcination includes a first isothermal treatment and a second isothermal treatment. The temperature of the first isothermal treatment is 150–250°C, such as 150°C, 160°C, 180°C, 200°C, 220°C, or 250°C, and the first isothermal treatment time is 3–6 hours, such as 3 hours, 3.5 hours, 4 hours, 5 hours, or 6 hours. The temperature of the second isothermal treatment is 300–600°C, such as 300°C, 350°C, 400°C, 500°C, or 600°C, and the second isothermal treatment time is 10–15 hours, such as 10 hours, 11 hours, 12 hours, 13 hours, or 15 hours. The calcination atmosphere is a protective gas, such as nitrogen or helium. The heating rates of the first and second isothermal treatments are each independent, ranging from 0.5 to 5°C / min.

[0058] In some embodiments, sieving is also included after calcination.

[0059] According to another aspect of the present invention, the present invention also relates to a positive electrode sheet comprising the aforementioned composite positive electrode material, or a composite positive electrode material prepared by the method for preparing the aforementioned composite positive electrode material.

[0060] The positive electrode of the present invention has excellent electrochemical performance, including a positive current collector and a positive electrode layer disposed on at least one side surface of the positive current collector, wherein the positive electrode layer contains the above-mentioned composite positive electrode material.

[0061] According to another aspect of the invention, the invention also relates to an aqueous zinc-ion battery, including the aforementioned positive electrode.

[0062] The aqueous zinc-ion battery of the present invention has excellent cycle stability.

[0063] The battery of the present invention further includes an electrolyte comprising a soluble zinc salt, a soluble lithium salt, and water. The soluble zinc salt comprises ZnSO4·7H2O, and the soluble lithium salt comprises Li2SO4. The concentration of the soluble zinc salt is 0.7–1.2 mol / L, for example, 0.7 mol / L, 0.9 mol / L, 1 mol / L, 1.2 mol / L, etc., and the concentration of the soluble lithium salt is 0.2–0.5 mol / L, for example, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, or 0.5 mol / L, etc.

[0064] The battery of the present invention uses the above-mentioned composite positive electrode material in combination with the above-mentioned electrolyte, Li + / Zn 2+ The dual charge carriers give it higher energy density and voltage window. The composite cathode material paired with a zinc metal anode has a higher output voltage of 1.8V, which is significantly higher than the 1.6V of traditional vanadium-based cathode materials (VO2, V2O5), and has higher energy density potential.

[0065] In some embodiments, the method for preparing the electrolyte includes: mixing a soluble zinc salt, a soluble lithium salt, and water at a mixing speed of 100–300 rpm, such as 100 rpm, 150 rpm, 200 rpm, 250 rpm, or 300 rpm, for a mixing time of 10–30 min, such as 10 min, 15 min, 20 min, or 25 min. The electrolyte preparation method of the present invention can obtain a high-performance electrolyte.

[0066] According to another aspect of the invention, the invention also relates to an electrical device comprising the aforementioned aqueous zinc-ion battery.

[0067] The following explanation, combined with specific embodiments and comparative examples, further illustrates the point.

[0068] Example 1

[0069] A method for preparing a composite cathode material includes the following steps:

[0070] (1) The manganese ferrous phosphate precursor (Mn) synthesized by coprecipitation method 0.6 Fe 0.4 )3(PO4)2·6H2O was placed in a box furnace for sintering. The sintering atmosphere was nitrogen, the sintering temperature was 500℃, and the sintering time was 4h to obtain anhydrous ferrous manganese phosphate precursor.

[0071] (2) Weigh 500g of anhydrous ferrous manganese phosphate obtained in step (1), add it to a mixing tank, add 317g of lithium phosphate, then add 71.47g of starch, 71.47g of polyethylene glycol, 5.96g of ammonium metavanadate and 2199g of deionized water, stir for 25 minutes and then transfer to a sand mill for grinding to obtain material a.

[0072] (3) Prepare a 10% solid content aqueous solution of titanium nitride and then disperse it under high pressure using a high pressure micro-jet homogenizer. The equipment pressure is 20000 psi and the flow rate is 200 mL / min. After dispersion, it is ready for use and is referred to as solution b.

[0073] (4) Mix material a and solution b, and stir at 500 rpm for 60 min. The prepared solution is called solution c.

[0074] (5) Spray dry the prepared solution c. Spray pressure: 0.2MPa, air inlet temperature: 200℃, feed rate (peristalsis speed): 20rpm.

[0075] (6) After spray drying, the material is sieved through a 400-mesh sieve and then calcined in a tube furnace at 200℃ for 5 hours and 350℃ for 12 hours. The heating rate is 1℃ / min and the nitrogen atmosphere is 1L / min.

[0076] (7) The calcined material is sieved through a 400-mesh sieve and then packaged to obtain a composite cathode material. The mass content of TiN in the composite cathode material is 5%.

[0077] The scanning electron microscope image of the composite cathode material in this embodiment is shown below. Figure 1 As shown.

[0078] A method for preparing a battery includes the following steps:

[0079] The composite positive electrode material, conductive carbon black, and binder polyvinylidene fluoride (PVDF) described in this embodiment were mixed in a mass ratio of 90:5:5. Using N-methylpyrrolidone (NMP) as a solvent, the mixture was prepared into a slurry, uniformly coated onto aluminum foil, dried at a suitable temperature, rolled to the required thickness, and vacuum dried at 120°C for 12 hours to obtain the positive electrode sheet. The negative electrode used was zinc foil, the separator was a glass fiber separator, and the electrolyte was 1 mol / L ZnSO4 + 0.1 mol Li2SO4. The electrolyte preparation method included dissolving 14.38 g of ZnSO4·7H2O and 0.55 g of Li2SO4 in 50 mL of deionized water, stirring at 200 rpm for 20 min to obtain an aqueous zinc-ion battery electrolyte with a Li2SO4 concentration of 0.1 mol / L and a ZnSO4 concentration of 1 mol / L.

[0080] Example 2

[0081] A method for preparing a composite cathode material includes the following steps:

[0082] (1) Ferrous manganese phosphate precursor (Mn) obtained by precipitation method 0.6 Fe 0.4 )3(PO4)2·6H2O was placed in a box furnace for sintering. The sintering atmosphere was nitrogen, the sintering temperature was 500℃, and the sintering time was 4h to obtain anhydrous ferrous manganese phosphate precursor.

[0083] (2) Weigh 500g of anhydrous ferrous manganese phosphate obtained in step 1 and add it to a mixing tank. Then add 317g of lithium phosphate, 71.47g of starch, 71.47g of polyethylene glycol, 5.96g of ammonium metavanadate and 2199g of deionized water. After stirring for 25 minutes, transfer it to a sand mill for grinding to obtain material a.

[0084] (3) Prepare a 7% solid content aqueous solution of titanium nitride and then disperse it under high pressure using a high pressure micro-jet homogenizer with a pressure of 20000 psi and a flow rate of 200 mL / min. After dispersion, it is ready for use and is referred to as solution b.

[0085] (4) Mix material a and solution b, and stir at 500 rpm for 60 min. The prepared solution is called solution c.

[0086] (5) Spray dry the prepared solution c. Spray pressure: 0.2MPa, air inlet temperature: 200℃, feed rate (peristalsis speed): 20rpm.

[0087] (6) After spray drying, the material is sieved through a 400-mesh sieve and then calcined in a tube furnace at 200℃ for 5 hours and 350℃ for 12 hours. The heating rate is 1℃ / min and the nitrogen atmosphere is 1L / min.

[0088] (7) The calcined material is sieved through a 400-mesh sieve and then packaged to obtain a composite cathode material. The mass content of TiN in the composite cathode material is 7%.

[0089] The method for preparing a battery includes the following steps:

[0090] The composite positive electrode material, conductive carbon black, and binder polyvinylidene fluoride (PVDF) described in this embodiment were mixed in a mass ratio of 90:5:5. Using N-methylpyrrolidone (NMP) as a solvent, the mixture was prepared into a slurry, uniformly coated onto aluminum foil, dried at a suitable temperature, rolled to the required thickness, and vacuum dried at 120°C for 12 hours to obtain the positive electrode sheet. The negative electrode used was zinc foil, the separator was a glass fiber separator, and the electrolyte was 1 mol / L ZnSO4 + 0.1 mol / L Li2SO4. The electrolyte preparation method included dissolving 14.38 g of ZnSO4·7H2O and 0.55 g of Li2SO4 in 50 mL of deionized water, and rotating at 200 rpm to obtain an aqueous zinc-ion battery electrolyte. The concentration of Li2SO4 was 0.1 mol / L, and the concentration of ZnSO4 was 1 mol / L.

[0091] Example 3

[0092] A method for preparing a composite cathode material includes the following steps:

[0093] (1) The manganese ferrous phosphate precursor (Mn) synthesized by coprecipitation method 0.6 Fe 0.4 )3(PO4)2·6H2O was placed in a box furnace for sintering. The sintering atmosphere was nitrogen, the sintering temperature was 500℃, and the sintering time was 4h to obtain anhydrous ferrous manganese phosphate precursor.

[0094] (2) Weigh 500g of anhydrous ferrous manganese phosphate obtained in step 1 and add it to a mixing tank. Then add 317g of lithium phosphate, 71.47g of starch, 71.47g of polyethylene glycol, 5.96g of ammonium metavanadate and 2199g of deionized water. After stirring for 25 minutes, transfer it to a sand mill for grinding to obtain material a.

[0095] (3) Prepare a 5% solid content aqueous solution of titanium nitride and then disperse it under high pressure using a high pressure micro-jet homogenizer. The equipment pressure is 20000 psi and the flow rate is 200 mL / min. After dispersion, it is ready for use and is referred to as solution b.

[0096] (4) Mix material a and solution b, and stir at 500 rpm for 60 min. The prepared solution is called solution c.

[0097] (5) Spray dry the prepared solution c with a spray pressure of 0.2 MPa, an air inlet temperature of 200℃, and a feed rate (peristaltic speed) of 20 rpm.

[0098] (6) After spray drying, the material is sieved through a 400-mesh sieve and then calcined in a tube furnace at 200℃ for 5 hours and 350℃ for 12 hours. The heating rate is 1℃ / min and the nitrogen atmosphere is 1L / min.

[0099] (7) The calcined material is sieved through a 400-mesh sieve and then packaged to obtain a composite cathode material. The mass content of TiN in the composite cathode material is 5%.

[0100] The method for preparing a battery includes the following steps:

[0101] The composite positive electrode material, conductive carbon black, and binder polyvinylidene fluoride (PVDF) described in this embodiment were mixed in a mass ratio of 90:5:5. Using N-methylpyrrolidone (NMP) as a solvent, the mixture was prepared into a slurry, uniformly coated onto aluminum foil, dried at a suitable temperature, rolled to the required thickness, and vacuum dried at 120°C for 12 hours to obtain the positive electrode sheet. The negative electrode used was zinc foil, the separator was a glass fiber separator, and the electrolyte was 1 mol / L ZnSO4 + 0.5 mol Li2SO4. The electrolyte preparation method included dissolving 14.38 g ZnSO4·7H2O and 0.55 g Li2SO4 in 50 mL of deionized water, stirring at 200 rpm for 20 min to obtain an aqueous zinc-ion battery electrolyte with a Li2SO4 concentration of 0.1 mol / L and a ZnSO4 concentration of 1 mol / L.

[0102] Example 4

[0103] The preparation method of the composite cathode material is the same as in Example 1.

[0104] The battery preparation method differs from that in Example 1 in that the electrolyte is 0.2 mol / L ZnSO4 + 0.9 mol Li2SO4. 12.51 g ZnSO4·7H2O and 1.1 g Li2SO4 are dissolved in 50 mL of deionized water and stirred at 200 rpm for 20 min to obtain an aqueous zinc-ion battery electrolyte with a Li2SO4 concentration of 0.2 mol / L and a ZnSO4 concentration of 0.9 mol / L.

[0105] Example 5

[0106] The preparation method of the composite cathode material is the same as in Example 1.

[0107] The battery preparation method differs from that in Example 1 in that the electrolyte is 0.4 mol / L Li₂SO₄ + 0.7 mol / L ZnSO₄. The electrolyte preparation method includes: dissolving 9.73 g ZnSO₄·7H₂O and 2.2 g Li₂SO₄ in 50 mL of deionized water, stirring and mixing at 200 rpm for 20 min to obtain an aqueous zinc-ion battery electrolyte with a Li₂SO₄ concentration of 0.4 mol / L and a ZnSO₄ concentration of 0.7 mol / L.

[0108] Example 6

[0109] A method for preparing a composite cathode material includes the following steps:

[0110] (1) Ferrous manganese phosphate precursor (Mn) obtained by precipitation method 0.6 Fe 0.4 )3(PO4)2·6H2O was placed in a box furnace for sintering. The sintering atmosphere was nitrogen, the sintering temperature was 400℃, and the sintering time was 6h to obtain anhydrous ferrous manganese phosphate precursor.

[0111] (2) Weigh 500g of anhydrous ferrous manganese phosphate obtained in step 1 and add it to a mixing tank. Then add 317g of lithium phosphate, 80g of maltose, 80g of polyvinyl alcohol, 5.32g of niobium pentoxide and 2300g of deionized water. After stirring for 20 minutes, transfer it to a sand mill for grinding to obtain material a.

[0112] (3) Prepare an aqueous solution of titanium nitride with a solid content of 7%, and then use a high-pressure micro-jet homogenizer to disperse it under high pressure. The equipment pressure is 15000psi and the flow rate is 80mL / min. After dispersion, it is ready for use and is referred to as solution b.

[0113] (4) Mix material a and solution b, and stir at 600 rpm for 45 minutes. The prepared solution is called solution c.

[0114] (5) Spray dry the prepared solution c. Spray pressure: 0.3MPa, air inlet temperature: 250℃, feed rate (peristalsis speed): 20rpm.

[0115] (6) After spray drying, the material is sieved through a 400-mesh sieve and then calcined in a tube furnace at 150℃ for 6 hours and 500℃ for 5 hours. The heating rate is 2℃ / min and the nitrogen atmosphere is 1L / min.

[0116] (7) The calcined material is sieved through a 400-mesh sieve and then packaged to obtain a composite cathode material. The mass content of TiN in the composite cathode material is 10%.

[0117] A method for preparing a battery, except that the composite cathode material used in this embodiment is used, is the same as in Example 1.

[0118] Example 7

[0119] A method for preparing a composite cathode material includes the following steps:

[0120] (1) Ferrous manganese phosphate precursor (Mn) obtained by precipitation method 0.6 Fe 0.4 )3(PO4)2·6H2O was placed in a box furnace for sintering. The sintering atmosphere was nitrogen, the sintering temperature was 600℃, and the sintering time was 4h to obtain anhydrous ferrous manganese phosphate precursor.

[0121] (2) Weigh 500g of anhydrous ferrous manganese phosphate obtained in step 1 and add it to a mixing tank. Then add 317g of lithium phosphate, 90g of sucrose, 45g of polyethylene glycol, 5.46g of vanadium pentoxide and 2250g of deionized water. After stirring for 20 minutes, transfer it to a sand mill for grinding to obtain material a.

[0122] (3) Prepare an aqueous solution of titanium nitride with a solid content of 7%, and then use a high-pressure micro-jet homogenizer to disperse it under high pressure. The equipment pressure is 10000psi and the flow rate is 100mL / min. After dispersion, it is ready for use and is referred to as solution b.

[0123] (4) Mix material a and solution b, and stir at 450 rpm for 60 min. The prepared solution is called solution c.

[0124] (5) Spray dry the prepared solution c. Spray pressure: 0.1MPa, air inlet temperature: 150℃, feed rate (peristalsis speed): 30rpm.

[0125] (6) After spray drying, the material is sieved through a 400-mesh sieve and then calcined in a tube furnace at 250℃ for 3 hours and 400℃ for 13 hours. The heating rate is 1℃ / min and the nitrogen atmosphere is 1L / min.

[0126] (7) The calcined material is sieved through a 400-mesh sieve and then packaged to obtain a composite cathode material. The mass content of TiN in the composite cathode material is 12%.

[0127] A method for preparing a battery, except that the composite cathode material used in this embodiment is used, is the same as in Example 1.

[0128] Comparative Example 1

[0129] A method for preparing a positive electrode material includes the following steps:

[0130] (1) The manganese ferrous phosphate precursor (Mn) synthesized by coprecipitation method 0.6 Fe 0.4 )3(PO4)2·6H2O was placed in a box furnace for sintering. The sintering atmosphere was nitrogen, the sintering temperature was 500℃, and the sintering time was 4h to obtain anhydrous ferrous manganese phosphate precursor.

[0131] (2) Weigh 500g of anhydrous ferrous manganese phosphate obtained in step 1 and add it to a mixing tank. Then add 317g of lithium phosphate, 71.47g of starch, 71.47g of polyethylene glycol, 5.96g of ammonium metavanadate and 2199g of deionized water. After stirring for 25 minutes, transfer it to a sand mill for grinding to obtain material a.

[0132] (3) Spray dry the prepared C solution with a spray pressure of 0.2 MPa, an air inlet temperature of 200℃, and a feed rate (peristaltic speed) of 20 rpm.

[0133] (4) After spray drying, the material is sieved through a 400-mesh sieve and then calcined in a tube furnace at 200℃ for 5 hours and 350℃ for 12 hours. The heating rate is 1℃ / min and the nitrogen atmosphere is 1L / min.

[0134] (5) The calcined material is sieved through a 400-mesh sieve and then packaged to obtain the finished product sample LiFe. 0.4 Mn 0.6 PO 4。

[0135] The battery was prepared using the same conditions as in Example 1, except that it used the composite cathode material described in this comparative example.

[0136] Comparative Example 2

[0137] The battery preparation method differs from that in Example 1 in that the electrolyte is 1 mol / L ZnSO4. The preparation method of the electrolyte includes: dissolving 14.35 g of ZnSO4·7H2O in 50 mL of deionized water, stirring and mixing at 200 rpm for 20 min to obtain an aqueous zinc-ion battery electrolyte with a ZnSO4 concentration of 1 mol / L.

[0138] Experimental Example

[0139] The electrochemical performance of the batteries obtained in each example and comparative example was tested, and the results are shown in Table 1. Initial specific capacity test conditions: 1C, 0V-1.8V test, 1C = 300mAh / g.

[0140] Table 1. Electrochemical performance test results of the battery

[0141]

[0142]

[0143] As shown in Table 1, the battery obtained by combining the composite cathode material of the present invention with the electrolyte has a Li + / Zn 2+ The dual-carrier design gives it higher energy density and voltage window, with an initial efficiency of ≥80.9% and a capacity retention of over 88% after 100 cycles.

[0144] In Comparative Example 1, the surface of the cathode material was not coated with titanium nitride, resulting in a battery with low initial efficiency and low capacity retention after 100 cycles.

[0145] In Comparative Example 2, the electrolyte was 1 mol / L ZnSO4, and the resulting battery had reduced capacity, significantly reduced initial efficiency, and reduced cycle performance.

[0146] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An aqueous zinc-ion battery, characterized in that, It includes a positive electrode sheet and an electrolyte; the positive electrode sheet includes a composite positive electrode material; the electrolyte includes a soluble zinc salt, a soluble lithium salt and water, the soluble zinc salt includes ZnSO4·7H2O, and the soluble lithium salt includes Li2SO4; The preparation method of the composite cathode material includes the following steps: Anhydrous ferrous manganese phosphate, lithium source, carbon source, dopant containing element M and solvent are mixed and ground to obtain the first material; the dispersion of titanium nitride is mixed and stirred with the first material, and then dried and calcined. The mixing speed is 200~600 rpm, and the mixing time is 10~30 min; The preparation of the titanium nitride dispersion specifically includes: subjecting a mixture of titanium nitride and water to high-pressure microjets; the pressure of the high-pressure microjets is 10,000~22,000 psi, the flow rate of the high-pressure microjets is 20~250 mL / min, and the time of the high-pressure microjets is 30~60 min. The calcination includes a first constant temperature treatment and a second constant temperature treatment, wherein the temperature of the first constant temperature treatment is 150~250℃ and the temperature of the second constant temperature treatment is 300~600℃. The composite cathode material includes a cathode matrix and a coating layer covering the surface of the cathode matrix; The positive electrode substrate includes a core material and a carbon material layer covering the surface of the core material. The core material includes lithium manganese iron phosphate material and a dopant element M. The dopant element M includes at least one of vanadium, titanium, niobium and magnesium. The coating layer includes titanium nitride; The mass of the coating layer is 2% to 20% of the mass of the composite cathode material.

2. The aqueous zinc-ion battery according to claim 1, characterized in that, It includes at least one of the following features (1) to (4): (1) The mass ratio of the anhydrous manganese ferrous phosphate, lithium source, carbon source, dopant containing element M and solvent is (300~600):(200~350):(120~200):(4~8):(1800~2500); (2) The carbon source includes at least one of starch, sucrose, fructose, maltose, cyclodextrin, citric acid and polyols; (3) The dopants containing element M include at least one of ammonium metavanadate, titanium dioxide, vanadium pentoxide, niobium pentoxide, anhydrous magnesium acetate and magnesium oxide; (4) The lithium source includes lithium phosphate.

3. The aqueous zinc-ion battery according to claim 1, characterized in that, It includes at least one of the following features (1) to (6): (1) The anhydrous ferrous manganese phosphate is obtained by heat treatment of ferrous manganese phosphate precursor; the heat treatment temperature is 500~600℃ and the heat treatment time is 4~6h. (2) The mass of the titanium nitride is 1% to 30% of the mass of the first material; (3) In the titanium nitride dispersion, the solid content of titanium nitride is 5%~30%; (4) The mixing speed is 300~600 rpm, and the mixing time is 30~70 min; (5) The drying is carried out by spray drying, the inlet air temperature of the spray drying is 150~250℃, and the pressure of the spray drying is 0.1~0.3MPa; (6) The first isothermal treatment time is 3~6h, and the second isothermal treatment time is 10~15h.

4. The aqueous zinc-ion battery according to claim 1, characterized in that, The concentration of the soluble zinc salt is 0.7~1.2 mol / L, and the concentration of the soluble lithium is 0.2~0.5 mol / L.

5. The aqueous zinc-ion battery according to claim 4, characterized in that, The method for preparing the electrolyte includes: mixing soluble zinc salt, soluble lithium salt and water at a speed of 100-300 rpm for 10-30 min.

6. An electrical appliance, characterized in that, The aqueous zinc-ion battery includes any one of claims 1 to 5.

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