CN116190810A

CN116190810A - Aqueous solution sodium ion battery

Info

Publication number: CN116190810A
Application number: CN202310161602.4A
Authority: CN
Inventors: 艾常春; 薛永萍; 张睿; 陈德权; 王泽平
Original assignee: Wuhan Institute of Technology
Current assignee: Wuhan Institute of Technology
Priority date: 2023-02-23
Filing date: 2023-02-23
Publication date: 2023-05-30

Abstract

The invention belongs to the technical field of sodium ion batteries, and particularly relates to an aqueous solution sodium ion battery. With NaTi ₂ (PO ₄ ) ₃ Polyanion titanium-based material is used as negative electrode active material, and polyanion Na is used as negative electrode active material ₂ FePO ₄ F is an anode active material, and NaTi is used ₂ (PO ₄ ) ₃ The three-dimensional framework structure of the battery realizes the rapid diffusion of sodium ions in a three-dimensional channel, improves the sodium ion conduction rate, and further improves the energy density of the battery; the positive and negative electrode active materials contain sodium ions, and the advantages of good circulation stability, air stability and the like of the polyanion electrode materials are well utilized, and the positive and negative electrode active materials are applied to an aqueous solution system, so that the advantages of low cost, stable circulation and the like are realized, and the safety performance of the battery is greatly improved.

Description

Aqueous solution sodium ion battery

Technical Field

The invention belongs to the technical field of sodium ion batteries, and particularly relates to an aqueous solution sodium ion battery.

Background

Each time the energy technology is innovated, the great progress of human civilization is promoted, and although the technology of converting renewable energy sources such as wind energy, solar energy, water energy and the like which are developed faster into electric energy has been rapidly developed in recent years, the conversion process is limited by the natural condition, so that the new energy power generation industry still faces serious resource waste. Therefore, development of a high-efficiency and convenient large-scale energy storage new technology is needed to realize sustainable development of new energy sources with green low carbon and high efficiency and saving.

At present, the storage of electric energy is mainly realized through technologies such as physical energy storage, chemical energy storage, electrochemical energy storage and the like. The electrochemical energy storage has the remarkable advantages of high energy density, high energy conversion efficiency, high response speed and the like, and has wide application prospect in the energy storage field, and the secondary battery which is easy to modularize is more interesting. Currently, secondary batteries that have entered into energy storage demonstration applications are mainly lead-acid batteries, high-temperature sodium batteries, vanadium flow batteries, and lithium ion batteries. However, these four types of batteries have respective limitations, such as low energy density of lead-acid batteries, low energy conversion efficiency of vanadium redox flow batteries, and shortage of lithium resources of lithium ion batteries, and thus new energy storage battery technologies must be developed to support sustainable development. In recent years, sodium ion batteries which are similar to the working principle of lithium ion batteries and are compatible in technology are favored by a plurality of scientific researchers because of abundant resources and low cost. The lithium battery can be widely applied to the fields of energy storage batteries, base station standby power supplies, low-speed quadricycles, electric two-wheelers and the like, and forms a complementary pattern with lithium batteries.

Most of reported sodium ion batteries are assembled by taking a carbon-based material as a negative electrode and Prussian blue or layered oxide as a positive electrode. For example, in 2019 Hu et al, a sodium ion battery using copper-doped copper-based layered oxide as a positive electrode material and amorphous carbon as a negative electrode material is proposed, so that serious domestic conflict of sodium ion battery technology is opened, and rapid development of a global low-speed electric vehicle is promoted. However, the carbon-based negative electrode material has problems of low initial coulomb efficiency, poor cycle stability and the like. Similarly, layered oxides and Prussian blue, which are cathode materials, have high specific capacities, but have poor cycle performance and are liable to cause environmental pollution.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide an aqueous solution sodium ion battery so as to solve the technical problems of low initial coulomb efficiency, poor circulation stability, easiness in causing environmental pollution and the like of the sodium ion battery in the prior art.

The invention provides an aqueous sodium ion battery, which comprises a positive electrode, a negative electrode and an electrolyte, wherein the positive electrode comprises a positive electrode active material, and the positive electrode active material is Na ₂ FePO ₄ F, performing the process; the negative electrode comprises a negative electrode active material which is NaTi ₂ (PO ₄ ) ₃ The method comprises the steps of carrying out a first treatment on the surface of the The electrolyte is an aqueous solution containing sodium salt.

Preferably, the positive electrode active material Na ₂ FePO ₄ The preparation method of F comprises the following steps:

(1) Sodium fluoride and FePO ₄ ·2H ₂ The O powder is ground and uniformly mixed to obtain mixed salt containing an iron source, a phosphorus source and a sodium source;

(2) Mixing the mixed aqueous solution of the sodium salt supplement and the carbon source with the mixed salt obtained in the step (1) and then carrying out hydrothermal reaction to obtain Na ₂ FePO ₄ F, precursor;

(3) Subjecting the Na of step (2) ₂ FePO ₄ F, sintering the precursor to obtain the Na-ion battery anode material ₂ FePO ₄ F。

Further preferably, the FePO of step (1) ₄ ·2H ₂ The average particle size of the O powder is 0.5 to 10. Mu.m, more preferably 2 to 6. Mu.m; the FePO ₄ ·2H ₂ The mol ratio of the O powder to the sodium fluoride is 1:1-2:1.

Preferably, the negative electrode active material NaTi ₂ (PO ₄ ) ₃ The preparation method of (2) comprises the following steps:

s1: adding a titanium source into a buffer solution of hydrogen peroxide and ammonia water to obtain a titanium source solution;

s2: organic acid, (NH) ₄ ) ₂ HPO ₄ Mixing sodium salt with the titanium source solution in the step S1 to obtain a mixed solution of a titanium source, a phosphorus source and a sodium source;

s3: mixing the dispersing agent with the mixed solution obtained in the step S2, and heating to disperse the dispersing agent to obtain a transparent product;

s4: carrying out hydrothermal reaction on the transparent product obtained in the step S3 to obtain NaTi ₂ (PO ₄ ) ₃ A precursor;

s5: the NaTi obtained in the step S4 is processed ₂ (PO ₄ ) ₃ Sintering the precursor in inert atmosphere to obtain NaTi as sodium ion negative electrode material ₂ (PO ₄ ) ₃ 。

Further preferably, the titanium source in the step S1 is tetrabutyl titanate and/or isobutyl titanate; the titanium source, the organic acid, (NH) ₄ ) ₂ HPO ₄ The mole ratio of the sodium salt is 1 (1-10): (1-15), and (0.1-1).

Further preferably, the molar ratio of the titanium source to the dispersing agent in the step S3 is 1:1 to 1:10, and the dispersing agent is ethylene glycol or polyethylene glycol.

Further preferably, the organic acid in step S2 is citric acid, tartaric acid or gluconic acid; the pH of the mixed solution in step S2 is 4 to 8, more preferably 5 to 7.

Preferably, the positive electrode further comprises a positive electrode current collector, a conductive agent and a binder, wherein the positive electrode active material, the conductive agent, the binder and the dispersing agent are mixed and then adhered to the positive electrode current collector to form the positive electrode;

the negative electrode also comprises a negative electrode current collector, a conductive agent and a binder, wherein the negative electrode active material, the conductive agent, the binder and the dispersing agent are mixed and then adhered to the negative electrode current collector to form the negative electrode.

Preferably, the porous PTEE membrane also comprises a membrane, wherein the membrane is one of non-woven fabrics, glass fibers, porous PP/PE membranes and porous PTEE membranes.

Preferably, the sodium salt is one or more of sodium bis (fluorosulfonyl) imide, sodium bis (trifluoromethanesulfonyl) imide, sodium perchlorate, sodium sulfate, sodium nitrate, sodium phosphate, sodium carbonate, and sodium oxalate.

Preferably, the conductive agent is selected from one or more of graphite, carbon black, carbon nanotubes and graphene;

and/or the adhesive is selected from one or more of polytetrafluoroethylene, polyacrylic acid, sodium alginate, polyvinyl alcohol, sodium carboxymethyl cellulose and styrene-butadiene latex;

and/or, the positive electrode current collector and the negative electrode current collector are each independently selected from one of a foil or mesh of titanium, copper, stainless steel, nickel.

Preferably, the mass ratio of the positive electrode active material, the conductive agent and the binder is 1: (0.1-0.8): (0.03-0.15);

the mass ratio of the anode active material to the conductive agent to the binder is 1: (0.1-1.8): (0.04-0.2).

According to another aspect of the present invention, there is provided an electronic device comprising the aqueous sodium ion battery.

In general, the above technical solutions conceived by the present invention have the following compared with the prior art

The beneficial effects are that:

(1) The invention provides an aqueous solution sodium ion battery, which uses NaTi ₂ (PO ₄ ) ₃ Polyanion titanium-based material is used as negative electrode active material, and polyanion Na is used as negative electrode active material ₂ FePO ₄ F is an anode active material, and NaTi is used ₂ (PO ₄ ) ₃ The three-dimensional framework structure of the battery realizes the rapid diffusion of sodium ions in a three-dimensional channel, improves the sodium ion conduction rate, and further improves the energy density of the battery; the positive and negative electrode active materials contain sodium ions, and the advantages of good circulation stability, air stability and the like of the polyanion electrode materials are well utilized, and the positive and negative electrode active materials are applied to an aqueous solution system, so that the advantages of low cost, stable circulation and the like are realized, and the safety performance of the battery is greatly improved.

(2) The invention provides a novel aqueous solution sodium ionSub-cell NaTi ₂ (PO ₄ ) ₃ /Na ₂ FePO ₄ The first reversible capacity of F can reach 130mAh/g, and has better safety and cycle stability. Meanwhile, the electrode material prepared in the invention has rich sources, in particular to a negative electrode material NaTi ₂ (PO ₄ ) ₃ The improved Pechni method is adopted, and the cost of the phosphorus source is greatly reduced. In the preferred embodiment of the invention Na is used ₂ SO ₄ The solution is electrolyte, so that the safety performance of the battery is better. Therefore, the novel sodium ion battery prepared by the method has wide application value and great market prospect.

(3) The novel aqueous solution sodium ion battery has simple assembly process and is easier to realize industrial production. The sodium ion battery has the advantages of low cost, high specific capacity, good cycle stability and the like. Therefore, the method can be popularized and applied in the technical field of chemical power supplies.

Drawings

FIG. 1 is a schematic diagram of the structure of an aqueous sodium ion battery of the present invention;

FIG. 2 shows the sodium ion negative electrode material NaTi prepared in step (1) of example 1 ₂ (PO ₄ ) ₃ X-ray diffraction phase analysis of (2);

FIG. 3 is a sodium ion positive electrode material Na of step (2) of example 1 ₂ FePO ₄ F X-ray diffraction phase analysis diagram;

in FIG. 4, content S1 and content S2 are NaTi obtained by comparative example 1 and example 1, respectively ₂ (PO ₄ ) ₃ Scanning electron microscope pictures of the cathode material;

FIG. 5 is the sodium ion battery anode material NaTi of example 1 and comparative example 1 ₂ (PO ₄ ) ₃ A first charge-discharge curve graph at 2C magnification;

FIG. 6 is the sodium ion battery anode material NaTi of example 1 and comparative example 1 ₂ (PO ₄ ) ₃ A cycle performance graph of (2);

FIG. 7 is a sodium ion battery NaTi of example 1 ₂ (PO ₄ ) ₃ /Na ₂ FePO ₄ F impedance diagrams at different temperatures;

FIG. 8 is a sodium ion battery NaTi of example 1 ₂ (PO ₄ ) ₃ /Na ₂ FePO ₄ F, a first-circle charge-discharge curve graph at different temperatures;

FIG. 9 is a sodium ion battery NaTi of example 1 ₂ (PO4) ₃ /Na ₂ FePO ₄ F ratio performance curves at different temperatures.

Detailed Description

The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.

The invention discloses a novel aqueous solution sodium ion battery which takes the bottleneck of development of a lithium ion battery, which is in shortage of resources, as a contract point, and can be used as a beneficial supplement of the lithium ion battery. The invention provides an aqueous solution sodium ion battery, which is shown in figure 1 and comprises a positive electrode, a negative electrode and electrolyte, wherein the positive electrode comprises a positive electrode active material, and the positive electrode active material is Na ₂ FePO ₄ F, performing the process; the negative electrode comprises a negative electrode active material which is NaTi ₂ (PO ₄ ) ₃ The method comprises the steps of carrying out a first treatment on the surface of the The electrolyte is an aqueous solution containing sodium salt.

Positive electrode active material Na adopted in aqueous solution sodium ion battery ₂ FePO ₄ F and the negative electrode active material is NaTi ₂ (PO ₄ ) ₃ Can be prepared by conventional preparation methods in the prior art, as long as the corresponding active material can be obtained. In some preferred embodiments, the positive electrode active material Na ₂ FePO ₄ The preparation method of F comprises the following steps:

In some embodiments, fePO in step (1) ₄ ·2H ₂ The average particle size of the O powder is 0.5 to 10. Mu.m, more preferably 2 to 6. Mu.m. Suitable FePO ₄ ·2H ₂ The granularity range of the O powder is more beneficial to preparing the Na with high specific capacity ₂ FePO ₄ And F, a positive electrode material. FePO of the above particle size range ₄ ·2H ₂ O powder may be obtained by various methods of preparation of ultrafine powders, in some embodiments, the FePO described in step (1) ₄ ·2H ₂ The O powder is FeSO ₄ ·7H ₂ O and H ₃ PO ₄ The powder material is prepared by adopting a turbulent circulation method for raw materials. The turbulent circulation method (or called turbulent circulation reaction method) is to change the flow direction of the material by using a flow guiding device in the stirring process, so that the material is in a turbulent state. In this state, the motion direction of each substance in the mixture has the characteristic of randomness, so that the mixture or dispersion among materials is quicker and more uniform, and each reactant can be contacted rapidly in a short time, thereby forming uniform microcrystalline particle products rapidly. The method is favorable for synthesizing superfine and high-purity powder materials. The invention adopts a turbulent circulation method to prepare the superfine FePO ₄ ·2H ₂ O powder as Na for preparing sodium ion positive electrode material ₂ FePO ₄ F an iron source and a phosphorus source.

In some embodiments of the invention, a turbulent circulation kettle is used for preparing FePO through turbulent circulation reaction ₄ ·2H ₂ O powder, the specific structure of which is disclosed in the document Hu Yi, etc., is synthesized into superfine lithium phosphate by a turbulent circulation method and is characterized by chemical engineering journal, 2014, (000) 003, 1099-1103). When the turbulent circulation kettle operates, the stator and the rotor start to rotate to enable FeSO ₄ ·7H ₂ O and H ₃ PO ₄ Dissolving in deionized water of a certain mass according to a certain proportion, adding excessive H ₂ O ₂ Until 1-10 phenanthrene-ethanol solution is used for detecting Fe in the now-prepared oxidation solution ²⁺ Completely become Fe ³⁺ . Then the prepared oxidizing solution is pumped into a turbulent circulation kettle, sucked into a stator from the bottom and mixed at high speed, and FePO with good surface morphology and uniform particle size distribution is synthesized by strictly controlling the conditions of turbulent circulation rate, reaction temperature, dropwise added NaOH concentration, final pH value, aging time, washing temperature, drying temperature, time and the like of a reaction system ₄ ·xH ₂ O. And then discharged from the meshes of the wall of the stator diversion cylinder to circulate in turn. Finally, the obtained FePO is ₄ ·xH ₂ Transferring the O dry powder into a cabinet type electric furnace, performing heat treatment for a certain time at a certain temperature, and removing crystal water to obtain micro-nano grade ferric phosphate powder. The principle is similar to that of an impinging stream reactor (Wuyuan, chemical progress, 2001,20 (11), 8-13), an impinging zone is formed in a stator, which is beneficial to promoting micromixing and preparing FePO of nano or submicron scale ₄ ·2H ₂ O powder.

When preparing the positive electrode active material in the experimental process of the invention, fePO ₄ ·2H ₂ The O powder provides an iron source and a phosphorus source, and the sodium fluoride provides a fluorine source and a sodium source, in some embodiments, the FePO described in step (1) ₄ ·2H ₂ The mol ratio of the O powder to the sodium fluoride is 1:1-2:1. The sodium salt supplement in the step (2) is sodium acetate, sodium oxalate or sodium citrate, the concentration of sodium ions in the mixed aqueous solution is 2-6 mol/L, the concentration of a carbon source is 0.1-0.5 g/mL, and the carbon source is sucrose and/or glucose. The molar ratio of the sodium salt supplement in the mixed aqueous solution in the step (2) to the sodium fluoride in the mixed salt in the step S1 is 0.5-1.2:1.

In some embodiments, in step (2), the mixed aqueous solution of the sodium salt supplement and the carbon source is mixed with the mixed salt in step S1 by ultrasound for 30-45 min before hydrothermal reaction. The sufficient ultrasonic mixing is helpful for preparing the nano-scale anode material.

In some embodiments, the hydrothermal reaction in step (2) is performed at a temperature of 40 to 180 ℃ for a reaction time of 10 to 40 hours. Experiments show that the hydrothermal temperature is not too high, otherwise, the sintering process is easy to agglomerate; on the other hand, the hydrothermal temperature is not too low, otherwise, the prepared precursor material has the bulk degreeInsufficient, collapse after sintering leads to a decrease in porosity of the cathode material, thereby leading to unstable electrochemical properties. The hydrothermal reaction process of the invention is essentially a rheological phase synthesis method (the mutual transformation between gas phase and liquid phase) by which Na with ideal porosity and bulk can be synthesized ₂ FePO ₄ And F, positive electrode material structure.

In some embodiments, the sintering of step (3) is specifically: pre-sintering for 1-5 h at 200-400 ℃ under inert atmosphere, and then sintering for 4-12 h at 500-800 ℃ to obtain Na ₂ FePO ₄ F sodium ion positive electrode material. Sintering is preferably performed in a rotary tube furnace to prevent agglomeration during sintering. The inert atmosphere may be N ₂ He, ar or N ₂ And Ar.

In some embodiments, the negative electrode active material, naTi ₂ (PO ₄ ) ₃ The preparation method of (2) comprises the following steps:

In some embodiments, the titanium source is tetrabutyl titanate and/or isobutyl titanate. The titanium source, the organic acid, (NH) ₄ ) ₂ HPO ₄ The mole ratio of the sodium salt is 1 (1-10): (1-15), 0.1-1); the molar ratio of the titanium source to the dispersing agent in the step S3 is 1:1-1:10, and the dispersing agent is ethylene glycolAlcohols or polyethylene glycols, more preferably ethylene glycol. In a preferred embodiment, the titanium source, the organic acid, (NH) ₄ ) ₂ HPO ₄ The mole ratio of the sodium salt is 1 (1-5): (1-5) and (0.1-1).

In some embodiments, the organic acid in step S2 is citric acid, tartaric acid, or gluconic acid; the pH of the mixed solution in the step S2 is 4 to 8, more preferably 5 to 7. In some embodiments, 30% H ₂ O ₂ And 28% NH ₃ ·H ₂ And (3) fully stirring and mixing O to obtain a buffer solution. Organic acid is used as a chelating agent of titanium ions in a titanium source, the chelate of the titanium ions is further mixed with a dispersing agent and then heated in a water bath to uniformly disperse the chelate of the titanium ions, and then hydrothermal reaction and sintering reaction are carried out to obtain a negative electrode material NaTi ₂ (PO ₄ ) ₃ . It was found in the experiment that the pH of the mixed solution of the titanium source, the phosphorus source and the sodium source obtained in the step S2 was relative to the NaTi finally obtained ₂ (PO ₄ ) ₃ Has a great influence on the electrochemical performance of (a). In some embodiments (NH) ₄ ) ₂ HPO ₄ As a phosphorus source, the pH of the obtained mixed solution is 6, and the obtained mixed solution is in a stable colloid shape; in experiments if NH is used ₄ H ₂ PO ₄ As a phosphorus source, the pH of the mixed solution was about 3, and a stable colloid could not be obtained; characterization demonstrated the use of (NH) ₄ )

₂ HPO ₄ As the phosphorus source, NH is adopted ₄ H ₂ PO ₄ As a phosphorus source, the corresponding electrochemical performance is obviously improved; it was also found in experiments that (NH) ₄ ) ₂ HPO ₄ As a phosphorus source, if the pH of the mixed solution is too small when the organic acid and the sodium salt are mixed, a stable colloidal mixed solution cannot be obtained even if the pH is adjusted to 6 by adding aqueous ammonia, and eventually the electrochemical properties of the prepared material are also affected.

In some embodiments, the sodium salt is sodium nitrate or sodium carbonate. To reduce cost, some embodiments dissolve sodium carbonate in dilute nitric acid solution to obtain sodium nitrate as a sodium source.

In some embodiments, step S3 mixes the dispersant with the result of step S2Mixing the mixed solution, and reacting at 60-100 ℃ for 1-8 h, preferably 2-5 h to obtain the transparent product. Step S4, the transparent product obtained in the step S3 is subjected to hydrothermal reaction for 1 to 8 hours at the temperature of 80 to 180 ℃, preferably, the transparent product is subjected to hydrothermal reaction for 2 to 6 hours at the temperature of 120 to 160 ℃ to obtain NaTi ₂ (PO ₄ ) ₃ A precursor.

In some embodiments, the inert atmosphere of step S5 is N ₂ He, ar or N ₂ A mixed gas with Ar; the sintering is specifically as follows: pre-sintering for 1-5 h at 200-400 ℃ and then secondary sintering for 4-12 h at 500-800 ℃.

In some embodiments, the positive electrode of the aqueous sodium ion battery further comprises a positive electrode current collector, a conductive agent and a binder, wherein the positive electrode active material, the conductive agent, the binder and the dispersing agent are mixed and then adhered to the positive electrode current collector to form the positive electrode; the negative electrode also comprises a negative electrode current collector, a conductive agent and a binder, wherein the negative electrode active material, the conductive agent, the binder and the dispersing agent are mixed and then adhered to the negative electrode current collector to form the negative electrode.

In some embodiments, the aqueous sodium ion battery of the present invention further comprises a separator, wherein the separator is one of a nonwoven fabric, a glass fiber, a porous PP/PE separator, and a porous PTEE film.

In some embodiments, the sodium salt used in the electrolyte of the aqueous sodium ion battery of the present invention is one or more of sodium bis (fluorosulfonyl) imide, sodium bis (trifluoromethanesulfonyl) imide, sodium perchlorate, sodium sulfate, sodium nitrate, sodium phosphate, sodium carbonate, and sodium oxalate.

In some embodiments, the conductive agent is selected from one or more of graphite, carbon black, carbon nanotubes, graphene; and/or the adhesive is selected from one or more of polytetrafluoroethylene, polyacrylic acid, sodium alginate, polyvinyl alcohol, sodium carboxymethyl cellulose and styrene-butadiene latex; and/or, the positive electrode current collector and the negative electrode current collector are each independently selected from one of a foil or mesh of titanium, copper, stainless steel, nickel; the dispersing agent is ethanol and other conventional dispersing agents and is used for improving the fluidity of the grinding and mixing process.

In some embodiments, the preparation method of the aqueous sodium ion battery comprises the following specific steps:

(1) The prepared sodium ion negative electrode material NaTi ₂ (PO ₄ ) ₃ Mixing (active material), conductive agent and binder in a certain proportion in an agate mortar, grinding uniformly, adding dispersant ethanol, grinding to prepare a bright thick paste, and then pressing and molding by a tablet press to obtain a negative electrode film;

(2) The prepared sodium ion positive electrode material Na ₂ FePO ₄ F (active substance), a conductive agent and a binder are mixed in an agate mortar according to a certain proportion, ground uniformly, added with dispersant ethanol, ground and prepared into a bright thick paste, and then pressed into a film by a tablet press to obtain a positive electrode film;

(3) Drying the negative electrode film prepared in the step (1) in a vacuum drying oven, and preparing into 1cm ² The square electrode plate of the anode electrode plate is obtained;

(4) Drying the positive electrode film prepared in the step (2) in a vacuum drying oven, and preparing into 1cm ² The square electrode plate of the anode electrode plate is obtained;

(5) Taking the negative electrode plate and the positive electrode plate prepared in the steps (3) and (4) as a negative electrode and a positive electrode of an assembled full battery respectively, taking a glass fiber diaphragm as a diaphragm, and taking 1M Na as a diaphragm ₂ SO ₄ And (3) taking the solution as electrolyte, assembling the electrolyte into a full battery, placing the full battery in an oven for standing to obtain the aqueous solution sodium ion battery, and placing the assembled full battery in the oven for standing for 2-20 h at the temperature of 20-80 ℃.

In some embodiments, the mass ratio of the positive electrode active material, the conductive agent, and the binder is 1: (0.1-0.8): (0.03-0.15); the mass ratio of the anode active material to the conductive agent to the binder is 1: (0.1-1.8): (0.04-0.2).

The invention also provides an electronic device comprising the aqueous solution sodium ion battery.

The invention designs and proposes that NaTi ₂ (PO ₄ ) ₃ Polyanion titanium-based material is used as negative electrode active material, and polyanion Na is used as negative electrode active material ₂ FePO ₄ F is the positive electrode activity of the sodium ion batteryMaterials using NaTi ₂ (PO ₄ ) ₃ The three-dimensional framework structure of the battery realizes the rapid diffusion of sodium ions in a three-dimensional channel, improves the sodium ion conduction rate, and further improves the battery energy density. The invention has the remarkable advantages that the polyanion NaTi is used ₂ (PO ₄ ) ₃ The negative electrode material is used as a negative electrode and takes polyanion Na as a negative electrode ₂ FePO ₄ F is taken as a positive electrode and Na is taken as ₂ SO ₄ The advantages of good circulation stability, air stability and the like of the polyanion electrode material are well utilized for the electrolyte, and the polyanion electrode material is also applied to an aqueous solution system, so that the cost is low, the circulation stability is realized, and the safety performance of the battery is greatly improved.

The following are examples:

example 1

A novel aqueous solution sodium ion battery and a preparation method thereof specifically comprises the following steps:

(1) Weighing 0.2g of sodium ion anode material NaTi prepared ₂ (PO ₄ ) ₃ (active substance), 0.03g of conductive agent (acetylene black) and 0.01g of binder (polytetrafluoroethylene) are put into an agate mortar, dispersant ethanol is added, and the mixture is ground and prepared into a bright thick paste, and then pressed into a film by a tablet press for molding, thus obtaining a negative electrode film; wherein the negative electrode active material NaTi ₂ (PO ₄ ) ₃ The preparation method comprises the following specific steps: 40ml of 30% H are measured ₂ O ₂ And 28% of 15ml NH ₃ ·H ₂ Fully stirring and mixing O to obtain a buffer solution; weighing 3.0g of tetrabutyl titanate, slowly adding the tetrabutyl titanate into the prepared buffer solution, and fully stirring to obtain a titanium source; weighing 4.0g of citric acid, 2g (NH) ₄ ) ₂ HPO ₄ (dissolved in 10ml deionized water) and 0.5g NaNO ₃ (dissolved in 10ml deionized water), sequentially adding into the obtained solution, and fully stirring to obtain a mixed solution of a phosphorus source, a sodium source and a titanium source; the pH of the mixed solution was measured to be 6; 1.0g of ethylene glycol is weighed and added into the obtained solution, and the solution reacts for 1 hour in a constant-temperature water bath at 90 ℃ to obtain transparent liquid; transferring the obtained transparent solution into a hydrothermal kettle, and placing the hydrothermal kettle in a 160 ℃ oven for heating and preserving heat for 1h to obtain NaTi ₂ (PO ₄ ) ₃ A precursor; to be preparedNaTi ₂ (PO ₄ ) ₃ The precursor is placed in a tube furnace, presintered for 3h at 400 ℃ and secondarily sintered for 8h at 500 ℃ respectively under argon atmosphere, and the sodium ion negative electrode active material NaTi is obtained ₂ (PO ₄ ) ₃ 。

(2) Weighing 0.6g of the prepared sodium ion positive electrode material Na ₂ FePO ₄ F (active substance), 0.1g of conductive agent (acetylene black) and 0.04g of binder (polytetrafluoroethylene) are put into an agate mortar, dispersant ethanol is added, and the mixture is ground and prepared into a bright thick paste, and then a tablet press is used for film pressing and forming, so that a positive electrode film is obtained; wherein the positive electrode active material Na ₂ FePO ₄ The preparation method of F comprises the following specific steps: grinding 3.6g of ferrous phosphate powder with average granularity of 4 mu m and 1.0g of NaF in an agate mortar for 30min to obtain mixed salt; weigh 1.8g CH ₃ COONa is dissolved in 4ml deionized water, 1.0g sucrose is added, and the solution is stirred until the solution is transparent, thus obtaining transparent solution; and (3) placing the prepared mixed salt into a hydrothermal reaction kettle, slowly dropwise adding the obtained transparent solution into the hydrothermal reaction kettle, and stirring ultrasonically for 40min until uniformity. Placing the reaction kettle containing the mixed solution in an oven at 80 ℃ for heating and preserving heat for 20 hours to obtain Na ₂ FePO ₄ F, precursor; na to be prepared ₂ FePO ₄ F, placing the precursor in a rotary tube furnace, presintering for 3h at 300 ℃ and secondary sintering for 8h at 600 ℃ in sequence under argon atmosphere to obtain Na ₂ FePO ₄ F sodium ion positive electrode active material.

Wherein, ferric phosphate powder with average granularity of 4 mu m is synthesized into FePO by adopting a turbulent circulation method ₄ ·2H ₂ O. The preparation method comprises the following steps: feSO is carried out ₄ ·7H ₂ O and H ₃ PO ₄ Dissolving in deionized water according to a ratio of 3:1, adding excess H ₂ O ₂ (1.5 times of phosphoric acid) until the Fe in the freshly prepared oxidation solution is detected by using 1-10 g (phenanthroline) ethanol solution ²⁺ Completely become Fe ³⁺ . Then the prepared oxidizing solution is pumped into a turbulent circulation kettle, the turbulent circulation rate of a reaction system is strictly controlled to 3000r/min, the reaction temperature is 85 ℃, 10 percent NaOH concentration is dripped, the final pH value is 2.08, the aging time is 1h, the washing temperature is 60 ℃ for 4 times, the drying is 140 ℃ for 8h, the synthetic surface appearance is good,FePO with uniform particle size distribution ₄ ·xH ₂ O. Finally, the obtained FePO is ₄ ·xH ₂ Transferring the O dry powder into a cabinet electric furnace, performing heat treatment at 80 ℃ for 12 hours, and removing crystal water to obtain the ferric phosphate powder with the average granularity of 4 mu m.

(3) Placing the negative electrode film prepared in the step (1) in a vacuum drying oven at 60 ℃ for 10 hours, and preparing 1cm ² The square electrode plate of the anode electrode plate is obtained;

(4) Placing the positive electrode film prepared in the step (2) in a vacuum drying oven at 60 ℃ for 10 hours, and preparing 1cm ² The square electrode plate of the anode electrode plate is obtained;

(5) Taking the negative electrode plate and the positive electrode plate prepared in the steps (3) and (4) as a negative electrode and a positive electrode of an assembled full battery respectively, taking a glass fiber diaphragm as a diaphragm, and taking 1M Na as a diaphragm ₂ SO ₄ And (3) taking the solution as electrolyte, assembling the electrolyte into a full battery, and standing in an oven to obtain the aqueous solution sodium ion battery.

Example 2

(1) Weighing 0.1g of sodium ion anode material NaTi prepared ₂ (PO ₄ ) ₃ (active substance), 0.02g of conductive agent (acetylene black) and 0.008g of binder (polyvinylidene fluoride) are put into an agate mortar, dispersant propanol is added, and the mixture is ground and prepared into a bright thick paste, and then pressed into a film by a tablet press to obtain a negative electrode film; negative electrode material active material NaTi ₂ (PO ₄ ) ₃ The preparation method of (a) comprises the following steps: 40ml of 30% H are measured ₂ O ₂ And 28% of 15ml NH ₃ ·H ₂ Fully stirring and mixing O to obtain a buffer solution; weighing 3.0g of tetrabutyl titanate, slowly adding the tetrabutyl titanate into the prepared buffer solution, and fully stirring to obtain a titanium source; weighing 4.0g of citric acid, 1.75g (NH) ₄ ) ₂ HPO ₄ (dissolved in 10ml deionized water) and 0.3g Na ₂ CO ₃ (dissolved in 10ml 60% HNO) ₃ ) Sequentially adding the mixed solution into the obtained solution, and fully stirring to obtain a mixed solution of a phosphorus source, a sodium source and a titanium source; the pH of the mixed solution was measured to be 6; 1.0g of ethylene glycol was weighed and added to the resulting mixed solution at 80 DEG CPerforming constant-temperature water bath reaction for 3 hours to obtain a transparent solution; transferring the obtained transparent solution into a hydrothermal kettle, and placing the hydrothermal kettle in a 140 ℃ oven for heating and preserving heat for 3 hours to obtain sodium ion negative electrode material NaTi ₂ (PO ₄ ) ₃ A precursor; the prepared sodium ion negative electrode material NaTi ₂ (PO ₄ ) ₃ The precursor is placed in a tube furnace, presintered for 3h at 300 ℃ and secondarily sintered for 7h at 700 ℃ respectively in argon atmosphere, and the sodium ion anode material NaTi is obtained ₂ (PO ₄ ) ₃ 。

(2) Weighing 0.5g of the prepared sodium ion positive electrode material Na ₂ FePO ₄ F (active substance), 0.08g of conductive agent (acetylene black) and 0.02g of binder (polyvinylidene fluoride) are put into an agate mortar, added with dispersant propanol, ground and prepared into a bright thick paste, and then pressed into a film by a tablet press to obtain a positive electrode film; positive electrode material active material Na ₂ FePO ₄ The preparation method of F specifically comprises the following steps: 3.6g of ferric phosphate powder with average granularity of 4 mu m (the preparation method is the same as that of the example 1) and 1.0g of NaF are put into an agate mortar to be ground for 30min, thus obtaining mixed salt; weighing 6.0g of sodium citrate, dissolving in 6ml of deionized water, adding 1.0g of sucrose, and stirring to obtain a transparent solution; and (3) placing the mixed salt prepared in the step (2) into a hydrothermal reaction kettle, slowly adding the transparent solution obtained in the step (3) into the hydrothermal reaction kettle, and stirring by ultrasonic until the transparent solution is uniform. Placing the reaction kettle containing the mixed solution in a baking oven at 100 ℃ for heating and preserving heat for 18 hours to obtain Na ₂ FePO ₄ F, precursor; na to be prepared ₂ FePO ₄ F, placing the precursor in a tube furnace, presintering for 3h at 400 ℃ and secondary sintering for 8h at 700 ℃ in sequence under argon atmosphere to obtain Na ₂ FePO ₄ F sodium ion positive electrode material;

(3) Placing the negative electrode film prepared in the step (1) in a vacuum drying oven at 40 ℃ for 12 hours, and preparing 1cm ² The square electrode plate of the anode electrode plate is obtained;

(4) Placing the positive electrode film prepared in the step (2) in a vacuum drying oven at 40 ℃ for 12 hours, and preparing 1cm ² The square electrode plate of the anode electrode plate is obtained;

(5) The negative electrode plate and the positive electrode prepared in the steps (3) and (4) are electrically connectedThe pole pieces are respectively used as a negative electrode and a positive electrode of the assembled full battery, the glass fiber diaphragm is used as a diaphragm, and 1M Na is used as a diaphragm ₂ SO ₄ And (3) taking the solution as electrolyte, assembling the electrolyte into a full battery, and standing in an oven to obtain the aqueous solution sodium ion battery.

Example 3

(1) Weighing 0.5g of sodium ion anode material NaTi prepared ₂ (PO ₄ ) ₃ (active substance), 0.09g of conductive agent (acetylene black) and 0.08g of binder (styrene-butadiene rubber) are put into an agate mortar, dispersant isopropanol is added, and the mixture is ground and prepared into a bright thick paste, and then pressed into a film by a tablet press to obtain a negative electrode film; negative electrode material active material NaTi ₂ (PO ₄ ) ₃ The preparation method of (2) is the same as that of example 1;

(2) 1.2g of the prepared sodium ion positive electrode material Na is weighed ₂ FePO ₄ F (active substance), 0.8g of conductive agent (acetylene black) and 0.1g of binder (styrene-butadiene rubber) are put into an agate mortar, dispersant isopropanol is added, and the mixture is ground and prepared into a bright thick paste, and then the thick paste is pressed into a film by a tablet press to obtain a positive electrode film;

(3) Placing the negative electrode film prepared in the step (1) in a vacuum drying oven at 70 ℃ for 8 hours, and preparing 1cm ² The square electrode plate of the anode electrode plate is obtained;

(4) Placing the positive electrode film prepared in the step (2) in a vacuum drying oven at 70 ℃ for 8 hours, and preparing 1cm ² The square electrode plate of the anode electrode plate is obtained;

Example 4

(1) Weighing 0.8g of the prepared sodium ion anode materialNaTi ₂ (PO ₄ ) ₃ (active substance), 0.12g of conductive agent (acetylene black) and 0.08g of binder (styrene-butadiene rubber) are put into an agate mortar, dispersant isopropanol is added, and the mixture is ground and prepared into a bright thick paste, and then pressed into a film by a tablet press to obtain a negative electrode film; negative electrode material active material NaTi ₂ (PO ₄ ) ₃ The preparation method of (a) comprises the following steps: 40ml of 30% H are measured ₂ O ₂ And 28% of 15ml NH ₃ ·H ₂ Fully stirring and mixing O to obtain a buffer solution; 3.0g of tetrabutyl titanate is weighed and slowly added into the buffer solution prepared in the process, and fully stirred to obtain a titanium source; weighing 4.0g of citric acid, 2.0g (NH) ₄ ) ₂ HPO ₄ (dissolved in 10ml deionized water) and 0.5g Na ₂ CO ₃ (dissolved in 10ml 60% HNO) ₃ ) Sequentially adding the mixed solution into the obtained solution, and fully stirring to obtain a mixed solution of a phosphorus source, a sodium source and a titanium source; the pH of the mixed solution was measured to be 6; weighing 1.0g of polyethylene glycol (with molecular weight of 380-420), adding into the obtained mixed solution, and carrying out constant-temperature water bath at 60 ℃ for 4 hours to obtain transparent liquid; transferring the obtained transparent solution into a hydrothermal kettle, and placing the hydrothermal kettle in a baking oven at 120 ℃ for heating and preserving heat for 5 hours to obtain sodium ion negative electrode material NaTi ₂ (PO ₄ ) ₃ A precursor; the prepared sodium ion negative electrode material NaTi ₂ (PO ₄ ) ₃ The precursor is placed in a tube furnace, presintered for 4 hours at 400 ℃ and secondarily sintered for 6 hours at 800 ℃ respectively under argon atmosphere, and the sodium ion anode material NaTi is obtained ₂ (PO ₄ ) ₃ ；

(2) Weighing 2.0g of the prepared sodium ion positive electrode material Na ₂ FePO ₄ F (active substance), 0.5g of conductive agent (acetylene black) and 0.2g of binder (styrene-butadiene rubber) are put into an agate mortar, dispersant isopropanol is added, and the mixture is ground and prepared into a bright thick paste, and then the thick paste is pressed into a film by a tablet press to obtain a positive electrode film; positive electrode material active material Na ₂ FePO ₄ The preparation method of F specifically comprises the following steps: 3.6g of ferric phosphate powder with average granularity of 4 mu m (the preparation method is the same as that of the example 1) and 1.0g of NaF are put into an agate mortar to be ground for 30min, thus obtaining mixed salt; 3.0g of sodium oxalate is weighed and dissolved in 5ml of deionized water, 2.0g of glucose is added, and stirring is carried outObtaining transparent solution after the solution is transparent; and (3) placing the prepared mixed salt into a hydrothermal reaction kettle, slowly adding the obtained transparent solution into the hydrothermal reaction kettle, and stirring the solution with ultrasound until the solution is uniform. Placing the reaction kettle containing the mixed solution in a baking oven at 180 ℃ for heating and preserving heat for 10 hours to obtain Na ₂ FePO ₄ F, precursor; na to be prepared ₂ FePO ₄ F, placing the precursor in a tube furnace, presintering for 4h at 400 ℃ and secondary sintering for 10h at 800 ℃ in sequence under argon atmosphere to obtain Na ₂ FePO ₄ F sodium ion positive electrode material;

(3) Placing the negative electrode film prepared in the step (1) in a vacuum drying oven at 50 ℃ for 10 hours, and preparing 1cm ² The square electrode plate of the anode electrode plate is obtained;

(4) Placing the positive electrode film prepared in the step (2) in a vacuum drying oven at 50 ℃ for 10 hours, and preparing 1cm ² The square electrode plate of the anode electrode plate is obtained;

Example 5

(1) Weighing 0.5g of sodium ion anode material NaTi prepared ₂ (PO ₄ ) ₃ (active substance), 0.09g of conductive agent (acetylene black) and 0.04g of binder (polytetrafluoroethylene) are put into an agate mortar, dispersant propanol is added, and the mixture is ground and prepared into a bright thick paste, and then the thick paste is pressed into a film by a tablet press to obtain a negative electrode film; negative electrode material active material NaTi ₂ (PO ₄ ) ₃ The preparation method of (2) is the same as that of example 1;

(2) 1.5g of the prepared sodium ion positive electrode material Na is weighed ₂ FePO ₄ F (active substance), 0.6g of conductive agent (acetylene black) and 0.1g of binder (polytetrafluoroethylene) are put into an agate mortar, added with dispersant propanol, ground and prepared into a bright thick paste, and then pressed into a film by a tablet press to form, namelyObtaining a positive electrode film; positive electrode material active material Na ₂ FePO ₄ F was prepared in the same manner as in example 1;

(3) Placing the negative electrode film prepared in the step (1) in a vacuum drying oven at 60 ℃ for 8 hours, and preparing 1cm ² The square electrode plate of the anode electrode plate is obtained;

(4) Placing the positive electrode film prepared in the step (2) in a vacuum drying oven at 60 ℃ for 8 hours, and preparing 1cm ² The square electrode plate of the anode electrode plate is obtained;

Example 6

(1) Weighing 0.8g of sodium ion anode material NaTi prepared ₂ (PO ₄ ) ₃ (active substance), 0.1g of conductive agent (acetylene black) and 0.05g of binder (polyvinylidene fluoride) are put into an agate mortar, dispersant ethanol is added, and the mixture is ground and prepared into a bright thick paste, and then pressed into a film by a tablet press to obtain a negative electrode film; negative electrode material active material NaTi ₂ (PO ₄ ) ₃ The preparation method of (2) is the same as that of example 1;

(2) 2.4g of the prepared sodium ion positive electrode material Na is weighed ₂ FePO ₄ F (active substance), 0.6g of conductive agent (acetylene black) and 0.1g of binder (polyvinylidene fluoride) are put in an agate mortar, dispersant ethanol is added, and the mixture is ground and prepared into a bright thick paste, and then the thick paste is pressed and molded by a tablet press to obtain the anode film; positive electrode material active material Na ₂ FePO ₄ F was prepared in the same manner as in example 1;

(3) Placing the negative electrode film prepared in the step (1) in a vacuum drying oven at 70 ℃ for 7 hours, and preparing 1cm ² The square electrode plate of the anode electrode plate is obtained;

(4) Placing the positive electrode film prepared in the step (2) in a vacuum drying oven at 70 ℃ for 7 hours, and preparing 1cm ² The square electrode plate of the anode electrode plate is obtained;

Comparative example 1

Comparative example 1 other procedures were the same as in example 1 except that (NH ₄ ) ₂ HPO ₄ Replaced by NH ₄ H ₂ PO ₄ The mixed solution of the phosphorus source, the sodium source and the titanium source was obtained, and the pH of the mixed solution was measured to be 3.

Sodium ion negative electrode material NaTi prepared in step (1) of example 1 ₂ (PO ₄ ) ₃ Placing the mixture on an X-ray diffractometer to obtain sodium ion negative electrode material NaTi ₂ (PO ₄ ) ₃ X-ray diffraction phase analysis of (2). The result is consistent with the standard card ICDD#97-020-3038, and the prepared NaTi is proved ₂ (PO ₄ ) ₃ A substance. Na-ion cathode material prepared in step (2) of example 1 ₂ FePO ₄ F is placed on an X-ray diffractometer to obtain sodium ion anode material Na ₂ FePO ₄ The X-ray diffraction phase analysis of F is shown in FIG. 3. It can be seen that a clearly split triplet appears at 2θ=34.2 °, 20= =34.5° and 20=34.8° which is in comparison with Na ₂ FePO ₄ The characteristic peaks of F are consistent, which shows that Na is obtained by the method ₂ FePO ₄ And F, a positive electrode material.

And observing and processing the prepared sodium ion negative electrode material by using a scanning electron microscope to obtain an SEM (scanning electron microscope) diagram shown in fig. 4. Wherein, in FIG. 4, the content S1 and the content S2 are respectively the NaTi prepared in comparative example 1 and example 1 ₂ (PO ₄ ) ₃ Scanning electron microscope pictures of the cathode material. As is evident from the figure, the NaTi prepared in comparative example 1 ₂ (PO ₄ ) ₃ The negative electrode material has no obvious micro-nano secondary structure, the particles are more dispersed, the particle size of the primary particles is between 200 and 300nm, and the surface of the particles is rough and shapedThe regularity is not high. Whereas the NaTi prepared in example 1 ₂ (PO ₄ ) ₃ The cathode material has a micro-nano secondary structure with obvious but irregular morphology, the particle size of primary particles is 200-300 nm, and most of the particles are spherical or elliptic particles with smooth surfaces.

NaTi prepared as in example 1 ₂ (PO ₄ ) ₃ As a negative electrode material, electrochemical performance test was conducted using silver chloride as a reference electrode, and the results are shown in FIGS. 5 and 6, wherein S1 and S2 in FIGS. 5 and 6 are respectively NaTi prepared in comparative example 1 and example 1 ₂ (PO ₄ ) ₃ The negative electrode material has a charge-discharge curve at 2C rate, wherein fig. 5 is a first-turn charge-discharge curve, and fig. 6 is a first-40-turn cycle performance curve. As is apparent from FIG. 5, the initial specific discharge capacity of the material prepared in comparative example 1 was 108mAh/g, and the initial specific discharge capacity of the material prepared in example 1 was 120mAh/g. Meanwhile, as can be seen from FIG. 6, the discharge specific capacity of the material prepared in comparative example 1 after 40 circles is 74.5mAh/g, and the capacity retention rate is 68%. The material prepared in example 1 has a specific discharge capacity of 102mAh/g after 40 circles of circulation, and a capacity retention rate of 85.3%. And the sodium ion negative electrode material NaTi prepared in example 1 ₂ (PO ₄ ) ₃ The first discharge specific capacity of the battery can reach 120mAh/g, and is relatively close to the theoretical specific capacity. The other conditions of the comparative example 1 and the example 1 are the same, and the difference is that ammonium dihydrogen phosphate of the comparative example 1 is replaced by diamine hydrogen phosphate of the example 1, so that the prepared sodium titanium phosphate anode material has great difference in morphology and electrochemical performance, probably because the diamine hydrogen phosphate has stronger alkalinity relative to the ammonium dihydrogen phosphate, the neutrality of a reaction system is favorably maintained, the occurrence of hydrogen evolution reaction on an electrode is restrained, and the specific capacity and the cycling stability of a sodium ion battery are obviously improved; or different pH environments for the prepared NaTi ₂ (PO ₄ ) ₃ Has a certain influence on the crystal structure, so that the corresponding electrochemical properties are greatly different.

FIG. 7 is a sodium ion battery NaTi of example 1 ₂ (PO ₄ ) ₃ /Na ₂ FePO ₄ F at different temperatures (S1, S2,S3, S4 and S5 correspond to impedance diagrams of 20 ℃, 25 ℃, 30 ℃, 35 ℃ and 40 ℃ respectively, and the aqueous solution sodium ion battery has small resistance and generates large current under the same voltage. NaTi of sodium ion battery prepared in example 1 ₂ (PO ₄ ) ₃ /Na ₂ FePO ₄ F electrochemical performance tests were performed at different temperatures. FIGS. 8 and 9 are respectively the NaTi sodium ion battery of example 1 ₂ (PO ₄ ) ₃ /Na ₂ FePO ₄ F the first charge-discharge curve graph and the multiplying power performance curve graph at different temperatures (S1 corresponds to 25 ℃ and S2 corresponds to 35 ℃). The test result shows that the battery has higher reversible discharge specific capacity for the first time at 35 ℃ at 25 ℃ and can reach 130mAh/g. The temperature rise may be more conducive to intercalation of sodium ions between the anode and cathode, thereby increasing the rate of sodium ion conduction.

In conclusion, the aqueous solution sodium ion battery NaTi prepared by the invention ₂ (PO ₄ ) ₃ /Na ₂ FePO ₄ F has the advantages of low cost, high specific capacity, high temperature resistance, good cycle stability and the like, so the preparation method is suitable for popularization and application in the field of chemical power sources.

It will be readily appreciated by those skilled in the art that the foregoing description is merely a preferred embodiment of the invention and is not intended to limit the invention, but any modifications, equivalents, improvements or alternatives falling within the spirit and principles of the invention are intended to be included within the scope of the invention.

Claims

1. The aqueous solution sodium ion battery is characterized by comprising a positive electrode, a negative electrode and electrolyte, wherein the positive electrode comprises a positive electrode active material, and the positive electrode active material is Na ₂ FePO ₄ F, performing the process; the negative electrode comprises a negative electrode active material which is NaTi ₂ (PO ₄ ) ₃ The method comprises the steps of carrying out a first treatment on the surface of the The electrolyte is an aqueous solution containing sodium salt.

2. The aqueous sodium ion battery of claim 1, wherein the positive electrode active material Na ₂ FePO ₄ The preparation method of F comprises the following steps:

3. The aqueous sodium ion battery of claim 2, wherein the FePO of step (1) ₄ ·2H ₂ The average granularity of the O powder is 0.5-10 mu m; the FePO ₄ ·2H ₂ The mol ratio of the O powder to the sodium fluoride is 1:1-2:1.

4. The aqueous sodium ion battery of claim 1, wherein the negative active material, niti ₂ (PO ₄ ) ₃ The preparation method of (2) comprises the following steps:

5. The aqueous sodium ion battery of claim 4, wherein the titanium source in step S1 is tetrabutyl titanate and/or isobutyl titanate; the titanium source, the organic acid, (NH) ₄ ) ₂ HPO ₄ The mole ratio of the sodium salt is 1 (1-10): (1-15), and (0.1-1).

6. The aqueous sodium ion battery of claim 4, wherein the molar ratio of the titanium source to the dispersant in step S3 is 1:1 to 1:10, and the dispersant is ethylene glycol or polyethylene glycol.

7. The aqueous sodium ion battery of claim 4, wherein the organic acid in step S2 is citric acid, tartaric acid or gluconic acid; the pH of the mixed solution in the step S2 is 4 to 8, preferably 5 to 7.

8. The aqueous sodium ion battery of claim 1, wherein the positive electrode further comprises a positive electrode current collector, a conductive agent and a binder, wherein the positive electrode active material, the conductive agent, the binder and the dispersing agent are mixed and then adhered to the positive electrode current collector to form the positive electrode;

9. The aqueous sodium ion battery of claim 1, wherein the sodium salt is one or more of sodium bis (fluorosulfonyl) imide, sodium bis (trifluoromethanesulfonyl) imide, sodium perchlorate, sodium sulfate, sodium nitrate, sodium phosphate, sodium carbonate, sodium oxalate.

10. An electronic device comprising an aqueous sodium ion battery as claimed in any one of claims 1 to 9.