CN115132961A - A kind of sodium ion battery positive electrode and its preparation method and application - Google Patents

Abstract

The invention provides a positive pole piece of a sodium-ion battery, and a preparation method and application thereof ₂ ‑CF ₂ ] _n -, the branches of the fibrillatable polymer comprising-SO ₃ ^‑ The solid-state positive pole piece prepared by the method has lower transmission impedance than the solid-state positive pole piece prepared by using a non-ionic conductor, so that the solid-state battery prepared by the method has excellent rate performance.

Description

A kind of sodium ion battery positive electrode and its preparation method and application

technical field

The invention belongs to the technical field of sodium ion batteries, and relates to a positive pole piece of a sodium ion battery and a preparation method and application thereof.

Background technique

A sodium-ion battery is a rocking-chair secondary battery similar to a lithium-ion battery. Compared with lithium-ion batteries, the first ionization energy of sodium ions is lower, which makes sodium ions more stable, and it is not easy to precipitate dendrites at low temperatures, which brings more excellent safety, stability and low-temperature performance to sodium-ion batteries. Second, the molar conductivity of sodium ions is higher, and the electrochemical performance of sodium ion batteries is slightly better than that of lithium ion batteries. The supply and demand relationship of sodium resources is stable, and the price fluctuation is small. The sodium-ion solid-state battery is a battery technology that replaces the flammable organic liquid electrolyte with a non-flammable sodium-ion solid-state battery electrolyte, which greatly improves the safety of the battery system and can better adapt to high-energy positive and negative electrodes. And reduce the weight of the system to achieve a simultaneous increase in energy density.

At present, the solid cathode electrode in sodium-ion solid-state batteries is usually made by homogenization and coating process. In order to ensure the continuity of the electrolyte membrane, it is necessary to mix the binder, the solvent and the solid electrolyte particles in the homogenization step.

CN114023921A discloses a sodium ion battery positive pole piece and its preparation method and application, the active material of the sodium ion battery positive pole piece includes polytriphenylamine and/or polytriphenylamine derivative, which uses polytriphenylamine and/or Polytriphenylamine derivatives are used as cathode active materials. Polytriphenylamine and its derivatives have the fast charge-discharge transport framework of poly(paraphenylene) conductive polymers and exhibit excellent power characteristics. At the same time, they have high-energy redox groups of polyaniline. and has a higher energy density.

CN110429329A discloses a preparation method of an all-solid-state sodium ion battery, comprising: mixing sodium salt, organic solvent, additive and initiator to obtain a liquid mixture; coating the surface of the positive pole piece and/or the negative pole piece to form a solid electrolyte layer; encapsulation to obtain a sodium ion battery; after baking the sodium ion battery, inject it into a liquid mixture, and let it stand; heating the sodium ion battery to obtain an unactivated solid state sodium ion battery; converting the solid sodium ion battery into , degassing, and vacuum packaging to obtain an all-solid-state sodium-ion battery.

The sodium-ion batteries described in the above solutions all use conventional binders, the binders used do not have ionic conductivity, and when the binder is dissolved in the solvent and then dried, the binder will be coated on the solid electrolyte. On the surface of the particles, the ions are not transported smoothly between the particles, so that the ionic conductivity of the solid positive electrode sheet is significantly reduced, and eventually the rate performance and capacity of the battery are seriously lost. And because the binder will coat the particle surface of the solid electrolyte, the usage of the binder is increased; in addition, the addition of the solvent increases the drying, solvent recovery and other processes, which increases the cost and may cause environmental pollution. .

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a kind of positive pole piece of sodium ion battery and its preparation method and application. The fiberizable polymer connects the solid electrolyte particles, and the binder acts to conduct sodium ions between the particles. The solid-state positive electrode sheet has lower transmission impedance, so the solid-state battery prepared by it has excellent rate performance.

In order to achieve this object of the invention, the present invention adopts the following technical solutions:

In a first aspect, the present invention provides a positive electrode plate for a sodium ion battery, the positive electrode plate for a sodium ion battery includes a current collector and an active material layer disposed on the surface of the current collector, and the active material layer includes a sodium ion active material layer. A substance, a sodium ion solid electrolyte, a conductive agent, and a fiberizable polymer, the main chain of the fiberizable polymer containing -[CF ₂ -CF ₂ ] _n -, and the branched chain of the fiberizable polymer including - SO ₃ ^- .

Part of the fiberizable polymer of the present invention is: the main chain structure composed of -[CF ₂ -CF ₂ ] _n -, which provides the cohesive force and fiberizable properties of the polymer, and the other part is composed of Na ⁺ The branch chain formed by the ion exchange functional group -SO ₃ H, the branch chain forms -SO ₃ Na after Na ⁺ ion exchange, and plays the role of conducting sodium ions.

In the present invention, a polymer that can be fibrillated and can conduct sodium ions is used as a binder, and the polymer can be connected between the particles in part of the positive electrode active layer, or between the particles in all the positive electrode active layers. The solid electrolyte particles are connected by the filament-like fiberizable polymer, and the point-to-point contact between the fiberizable polymer and the solid electrolyte particles can effectively reduce the ion transfer impedance between the solid electrolyte particles and reduce the positive electrode. Ion transfer resistance between flake particles and improved mechanical properties. The solid battery prepared by this method has excellent rate performance and greatly reduces the amount of binder.

In the present invention, a polymer with ionic conductivity is used as a binder, which can play a role of conducting sodium ions between the particles while binding the particles. The solid-state positive electrode plate prepared by using the non-ionic conductor has lower transmission impedance, so the solid-state battery prepared by using the non-ionic conductor has excellent rate performance.

Preferably, the electrical conductivity of the fiberizable polymer is >5×10 ^-6 S/cm, for example: 5.2×10 ^-6 S/cm ^, 6×10 ^-6 S/cm, 7×10 ^-6 S/cm cm, 8×10 ^-6 S/cm, 9×10 ^-6 S/cm or 10×10 ^-6 S/cm, etc.

Preferably, the fiberizable polymer is in the form of filaments.

The invention uses filamentous polymer as the binder without the participation of the solvent. On the one hand, the contact and reaction of the solvent to the solid electrolyte is avoided, the impedance of the battery is reduced, and the rate performance of the battery is improved; on the other hand, the solvent is reduced. The energy required for evaporation and recovery avoids problems such as post-processing and recovery of organic solvents, effectively saving production costs and avoiding environmental pollution; at the same time, the preparation process is simple and easy to scale up, which is a method suitable for industrial applications and is conducive to promoting new technologies. The development of the energy industry has broad application prospects.

Preferably, there is point-to-point contact between the fiberizable polymer and the solid electrolyte particles.

Preferably, the thickness of the positive pole piece is 30-200 μm, for example: 30 μm, 50 μm, 80 μm, 100 μm, 150 μm or 200 μm, etc.

Preferably, the thickness of the current collector is <20 μm.

Preferably, the sodium ion active material includes any one or a combination of at least two of a layered oxide material, a polyanionic positive electrode material or a Prussian blue positive electrode material.

Preferably, the chemical formula of the layered oxide material is Na _x MO ₂ , wherein x≤1, and M is any one or a combination of at least two of Ni, Mn, Fe, Co or Cu.

Preferably, the chemical formula of the polyanionic positive electrode material is Na _{x My} (AO ₄ ) _z (P ₂ O ₇ ) _w , wherein 2≤x≤4, 1≤y≤4, 0≤z≤4, 0≤w≤1, M includes any one or a combination of at least two of Ti, V, Cr, Mn, Fe, Co, Ni, Cu or Zn, A includes Al, Si, P, S, Ti, V Or any one of W or a combination of at least two of them, and M is an electroactive transition metal.

Preferably, the chemical formula of the Prussian blue cathode material is A _x M[Fe(CN) ₆ ] _y ·zH ₂ O, wherein 0<x<2, 0<y<1, and A includes Li, Na or K Any one or a combination of at least two of M includes any one or a combination of at least two of Fe, Mn, Co, Ni or Cu.

Preferably, the sodium ion solid electrolyte comprises any one or a combination of at least two of Na-β-Al ₂ O ₃ , Na ₃ PS ₄ , Na ₃ SbS ₄ or Na ₁₁ Sn ₂ PS ₁₂ .

Preferably, the conductive agent comprises any one or a combination of at least two of acetylene black, Super-P, carbon nanotube, carbon fiber (VGCF), Ketjen black, graphite conductive agent or graphene.

Preferably, based on the mass of the active material layer as 100%, the mass fraction of the sodium ion active material is 55-90%, for example: 55%, 60%, 70%, 80% or 90%, etc., preferably 70 to 85%.

Preferably, the mass fraction of the conductive agent is 0.1-5%, for example: 0.1%, 0.5%, 1%, 3% or 5%, etc., preferably 1-2.5%.

Preferably, the mass fraction of the fiberizable polymer is 0.1-5%, for example: 0.1%, 0.5%, 1%, 3% or 5%, etc., preferably 0.5-3%.

In a second aspect, the present invention provides a method for preparing a sodium-ion battery positive electrode plate as described in the first aspect, the preparation method comprising the following steps:

(1) performing sodium ion exchange treatment on the fiberizable polymer, stirring and mixing the sodium ion positive electrode active material, solid electrolyte particles, conductive agent and fiberizable polymer to obtain a mixture;

(2) shearing and hot pressing the mixture obtained in step (1) to obtain a positive electrode active material layer;

(3) Coating the positive electrode active material layer obtained in step (2) on the surface of the current collector to obtain the sodium ion battery positive electrode sheet.

In the present invention, the fiberizable polymer is used as the binder, and without adding a solvent, the sodium ion active material, the sodium ion solid electrolyte and the conductive agent are first mixed; secondly, the fiberizable polymer and the above mixed particles are mixed at a low speed Mix evenly, and then carry out high-speed shear mixing. The fiberizable polymer can be elongated, thinned, and filamentized by using the characteristics that the fiberizable polymer can be filamentous under the action of external shearing force. , the filamentous fiberizable polymer is sticky and can bind the particles together; and since the fiberizable polymer exists in the form of filaments after filamentation, it is a point between the solid electrolyte particles- Point contact, which is different from the surface-to-surface contact between the binder and the particles in the traditional wet coating process, the method of the present invention can reduce the ion transmission resistance between the solid electrolyte particles and improve the mechanical properties. The solid-state battery has excellent rate performance and can reduce the amount of binder used compared to the traditional wet coating process.

In the present invention, the mixture is sheared and hot-pressed, so as to achieve the purpose of thinning the solid positive electrode piece and making the thickness uniform. After hot-pressing, a self-supporting independent positive electrode piece can be formed. The collector is hot-pressed composite. The positive electrode piece prepared by this process has good ductility and strong plasticity. After repeated rolling, it can achieve a high compaction density, which can effectively improve the volume energy density and mass energy density of the battery. No requirements, can be changed and customized according to actual requirements, with higher flexibility.

Preferably, the mode of the sodium ion exchange treatment comprises the following steps:

(A) mixing and soaking the fiberizable polymer and hydrochloric acid solution and washing to neutrality;

(B) the polymer obtained in step (1) is dried, sieved, mixed with sodium chloride solution, washed and dried to obtain a sodium ion-containing fiberizable polymer.

Taking PTFE as an example, its ion exchange steps are as follows:

Using FTIR to characterize the polymer prepared above, it can be seen that there are absorption peaks of -[CF ₂ -CF ₂ ] _n -segment groups around 1130cm ^-1 and 1200cm ^-1 , and at 1060cm ^- There is an absorption peak of -SO ₃ ^- group at ¹ .

Preferably, the speed of the high-speed mixing is 500-3000 rpm, for example: 500 rpm, 1000 rpm, 2000 rpm, 2500 rpm or 3000 rpm and the like.

In the present invention, if the rotational speed is too low and the time is too short, the external mechanical force is not enough to stretch the adhesive to make it filamentous, so that the adhesive cannot reach the optimal bonding state; if the rotational speed is too high, the time If it is too long, the excessively large external mechanical force will cause the adhesive to be overstretched, elongated and fractured, so that the adhesive will form fragmented short filaments, which will eventually lead to a decrease in the adhesive force.

Preferably, the high-speed mixing time is 10-60 minutes, for example: 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, or 60 minutes.

Preferably, the temperature of the hot pressing treatment is 50-220°C, for example: 50°C, 80°C, 100°C, 200°C or 220°C, and the like.

In a third aspect, the present invention provides a sodium-ion solid-state battery, the sodium-ion solid-state battery comprising the sodium-ion battery positive electrode plate described in the first aspect.

Compared with the prior art, the present invention has the following beneficial effects:

(1) The positive electrode sheet of the present invention uses a polymer that can be fiberized and can conduct sodium ions as a binder. Compared with the traditional wet coating process, no solvent is required; and the solid electrolyte particles are connected by filament-like fiberizable polymers, and the fiberizable polymer and the solid electrolyte particles are in point-to-point contact. The ion transport resistance between solid electrolyte particles can be effectively reduced, the ion transport resistance between positive electrode and pole piece particles can be reduced, and the mechanical properties can be improved. The solid battery prepared by this method has excellent rate performance and greatly reduces the amount of binder.

(2) The present invention uses a polymer with ionic conductivity as a binder, which can play a role of conducting sodium ions between the particles while binding the particles. The solid positive electrode prepared by this method The sheet has lower transmission impedance than the solid-state positive electrode sheet prepared by using the non-ionic conductor, so the solid-state battery prepared therefrom has excellent rate performance.

(3) The tensile strength of the positive electrode piece of the sodium ion battery according to the present invention can reach more than 115.2N/cm ² , the specific capacity of 0.33C discharge can reach more than 93.8mAh/g, and the specific capacity of 1C discharge can reach more than 90mAh/g, The 3C discharge specific capacity can reach more than 97.2mAh/g, the 1C/0.1C retention rate can reach more than 91.3%, and the 3C/0.1C retention rate can reach more than 87.6%.

Description of drawings

FIG. 1 is a SEM image of the positive electrode piece of the sodium-ion battery described in Example 1. FIG.

Figure 2 is an FTIR spectrum of the fiberizable polymer after sodium ion exchange.

Detailed ways

The technical solutions of the present invention are further described below through specific embodiments. It should be understood by those skilled in the art that the embodiments are only for helping the understanding of the present invention, and should not be regarded as a specific limitation of the present invention.

The sodium ion exchange process of the fibrillable polymers used in the examples of the present invention and the comparative examples is as follows:

1) First, soak 10g of the above-mentioned polymer in 100ml, 5mol/L of HCl solution for 32h;

2) Use excess deionized water to clean the above-mentioned polymer after soaking until the pH value is neutral;

3) drying the polymer obtained in step 2 at 120°C for 8h;

4) use 300-mesh ultrasonic vibrating screen to carry out sieving treatment of polymer particles in step 3, and take the material in the lower layer of the screen for subsequent use;

5) NaCl is dissolved in deionized water, and the mass concentration is 30%;

6) Mix 2 g of polymer particles obtained in step 4 with 50 ml of the solution in step 5, and stir at 1200 rpm for 30 h at 60°C;

7) using deionized water to clean the obtained polymer in step 6 to the surface without NaCl residue;

8) The polymer obtained in step 7 was dried at 120° C. for 8 h for use, and the FTIR spectrum of the obtained polymer was shown in FIG. 2 .

Example 1

The present embodiment provides a sodium ion battery positive pole piece, and the preparation method of the sodium ion battery positive pole piece is as follows:

(1) Put Na ₃ V ₂ (PO ₄ ) ₃ , Na ₃ PS ₄ and Super-P into a mixer, the ratio of each of the above-mentioned substances is 75:23:2, and stir for 60min at a stirring speed of 350rpm to obtain a mixture. The mixture and the fibrillable polymer after the sodium ion exchange are added together in the mixer for low-speed stirring and mixing, the ratio of the polymer and the mixture is 2:98, the stirring speed is 300rpm, and the stirring time is 20min to obtain the mixture;

(2) the above-mentioned mixture is sheared and mixed using a high-speed mixer to obtain a sheared mixture, the rotating speed of the high-speed stirring is 2500rpm, and the stirring time is 40min, and the sheared mixture is put into the roller press and hot-pressed processing to form a self-supporting positive electrode active material layer, wherein the hot pressing temperature is 60° C., the rolling speed is 50 cm/min, and the thickness of the positive electrode active material layer is 60 μm;

(3) Hot pressing the positive electrode active material layer and the aluminum foil together to obtain the positive electrode piece of the sodium ion battery.

The SEM image of the positive electrode plate is shown in Figure 1, the particles are solid electrolyte particles, the filamentous polymer is filamentous, and the filamentous polymer and solid electrolyte particles can be seen in the circle. point-to-point contact.

Example 2

The present embodiment provides a sodium ion battery positive pole piece, and the preparation method of the sodium ion battery positive pole piece is as follows:

(1) Put Na ₃ V ₂ (PO ₄ ) ₃ , Na ₃ SbS ₄ and VGCF into a mixer, the ratio of each of the above substances is 80:19:1, and stir for 80 min at a stirring speed of 400 rpm to obtain a mixture. Add the fibrillable polymer after the sodium ion exchange into the mixer for low-speed stirring and mixing, the ratio of the polymer to the mixture is 1:99, the stirring speed is 400rpm, and the stirring time is 20min to obtain the mixture;

(2) the above-mentioned mixed material is sheared and mixed using a high-speed mixer to obtain a sheared mixed material, the rotating speed of the described high-speed stirring is 3000rpm, and the stirring time is 40min, and the sheared mixed material is put into the roller press and hot-pressed processing to form a self-supporting positive electrode active material layer, wherein the hot pressing temperature is 80° C., the rolling speed is 60 cm/min, and the thickness of the positive electrode active material layer is 60 μm;

(3) Hot pressing the positive electrode active material layer and the aluminum foil together to obtain the positive electrode piece of the sodium ion battery.

Example 3

The only difference between this example and Example 1 is that the ratio of the polymer to the mixed material is 0.5:99.5, and other conditions and parameters are exactly the same as those of Example 1.

Example 4

The only difference between this example and Example 1 is that the ratio of the polymer to the mixed material is 3.5:96.5, and other conditions and parameters are exactly the same as those of Example 1.

Comparative Example 1

The present comparative example provides a method for preparing a sodium ion positive pole piece, comprising the following steps:

(1) put Na ₃ V ₂ (PO ₄ ) ₃ , Na ₃ PS ₄ and SP into the mixer, the above-mentioned respective material ratios are 75:23:2, and stir 60min at a stirring speed of 350rpm to obtain a mixture;

(2) the nitrile rubber and toluene solvent accounting for 2% of the mass of the whole powder are dissolved;

(3) using a homogenizer to homogenize the slurry dissolved in the step (2) and the mixed slurry in the step (1);

(4) Finally, the above slurry is coated with a coating machine at a coating speed of 1 m/min. After coating, it is dried at 90° C. for 2 hours to form a positive pole piece, and the thickness of the positive pole piece is 60 μm.

Comparative Example 2

This comparative example provides a preparation method of a sodium ion all-solid-state battery positive pole piece, comprising the following steps:

(1) put Na ₃ V ₂ (PO ₄ ) ₃ , Na ₃ SbS ₄ and VGCF into the mixer, the above-mentioned respective material ratios are 80:19:1, and stirred for 80min at a stirring speed of 400rpm to obtain a mixture;

(2) the nitrile rubber and toluene solvent accounting for 5% of the mass of the whole powder are dissolved;

(3) using a homogenizer to homogenize the slurry dissolved in the step (2) and the mixed slurry in the step (1);

(4) Finally, the above slurry is coated with a coating machine at a coating speed of 1 m/min. After coating, it is dried at 90° C. for 2 hours to form a positive pole piece, and the thickness of the positive pole piece is 60 μm.

Comparative Example 3

The only difference between this comparative example and Example 1 is that the polymer is not subjected to sodium ion exchange treatment, and other conditions and parameters are exactly the same as those of Example 1.

Performance Testing:

The electrical conductivity of each material in Example 1 and Comparative Example 1 is tested, and the test results are shown in Table 1:

Table 1

As can be seen from Table 1, due to the use of the polymer with sodium ion conductivity in the present invention as a binder, the "No. 2" sample has a higher sodium ion conductivity than the "No. 3" sample, which is also closer to The conductivity of the "No. 1" original sample, ie the sodium ion conduction impedance between the particles, is smaller. The "No. 2" and "No. 3" samples have higher electrical conductivity than the "No. 4" samples due to the use of a binder with fibrillation ability.

The positive pole pieces prepared in Examples 1-4 and Comparative Examples 1-3 were tested for tensile strength, and the positive pole pieces prepared above were cut into circular pieces with a diameter of 10 mm using a slicer, and 200 mg of sodium ion solid electrolyte was used. Na ₃ PS ₄ is placed in a mold sleeve with a diameter of 10 mm, and a pressure of 200 MPa is applied to make it into a sheet. Using metal Na as the negative electrode, the positive electrode and sodium sheet are respectively placed in the solid electrolyte prepared in step 2. The two sides of the sheet were formed, and the pressure of 50MPa was applied outside. The above-mentioned batteries were charged and discharged at the rate of 0.33C, 1C, and 3C. The test results are shown in Table 1:

Table 1

As can be seen from Table 1, from Examples 1-2, the tensile strength of the positive electrode piece of the sodium ion battery of the present invention can reach more than 115.2N/cm ² , and the discharge specific capacity at 0.33C can reach 102.8mAh/g Above, the 1C discharge specific capacity can reach more than 93.8mAh/g, the 3C discharge specific capacity can reach more than 90mAh/g, the 1C/0.1C retention rate can reach more than 91.3%, and the 3C/0.1C retention rate can reach more than 87.6%.

From the comparison between Example 1 and Examples 3-4, it can be seen that the addition amount of the fiberizable polymer in the positive electrode plate of the sodium ion battery of the present invention will affect the performance of the obtained positive electrode plate, and the fiberizable polymer The addition amount is controlled at 0.5-3%, and the performance of the prepared positive electrode sheet is good. If the addition amount of the fiberizable polymer is too large, due to its low ionic conductivity, too much addition will still hinder the ion transmission, thereby causing the rate performance to decline; if the addition amount of the fiberizable polymer is too small, the viscosity will Insufficient junction force results in poor performance of the pole piece model, inability to form a film, and the contact between particles is not tight, resulting in a decrease in electrical properties.

It can be seen from the comparison between Example 1 and Comparative Example 1 and Example 2 and Comparative Example 2 that the present invention connects the solid electrolyte particles through filament-like fiberizable polymers, and the fiberizable polymer and the solid electrolyte particles are connected between the particles. For point-to-point contact, the ion transfer impedance between solid electrolyte particles can be effectively reduced, the ion transfer impedance between positive electrode and pole piece particles can be reduced, and mechanical properties can be improved. Using a polymer with ionic conductivity as a binder, it can play a role of conducting sodium ions between the particles while binding the particles. The solid-state positive electrode plate prepared by the ion conductor has lower transmission impedance, so the solid-state battery prepared by it has excellent rate performance.

From the comparison between Example 1 and Comparative Example 3, it can be seen that the present invention performs sodium ion exchange treatment on the fiberizable polymer, which can make the polymer have a certain sodium ion transport capacity, thereby reducing the hindering effect of the polymer on ion transport, thereby Improve the capacity and rate performance of the pole piece.

The applicant declares that the above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should Changes or substitutions that can be easily conceived within the technical scope all fall within the protection scope and disclosure scope of the present invention.

Claims (10)

1. The positive pole piece of the sodium-ion battery is characterized by comprising a current collector and an active substance layer arranged on the surface of the current collector, wherein the active substance layer comprises a sodium-ion active substance, a sodium-ion solid electrolyte, a conductive agent and a fibrillatable polymer, and the main chain of the fibrillatable polymer comprises- [ CF ₂ -CF ₂ ] _n -, the branches of the fibrillatable polymer comprising-SO ₃ ^- 。

2. The positive electrode sheet of the sodium-ion battery of claim 1, wherein the fibrillatable polymer has a conductivity > 5 x 10 ^-6 S/cm。

3. The positive electrode sheet of the sodium-ion battery of claim 1 or 2, wherein the fiberizable polymer is in the form of filaments;

preferably, there is point-to-point contact between the fibrillatable polymer and the solid electrolyte particles.

4. The positive electrode plate of the sodium-ion battery as claimed in any one of claims 1 to 3, wherein the thickness of the positive electrode plate is 30 to 200 μm;

preferably, the thickness of the current collector is < 20 μm.

5. The positive electrode plate of the sodium-ion battery of any one of claims 1 to 4, wherein the sodium-ion active material comprises any one of or a combination of at least two of a layered oxide material, a polyanionic positive electrode material or a Prussian blue positive electrode material;

preferably, the layered oxide material has the chemical formula Na _x MO ₂ Wherein x is less than or equal to 1, and M is any one or the combination of at least two of Ni, Mn, Fe, Co or Cu;

preferably, the polyanionic cathode material has a chemical formula of Na _x M _y (AO ₄ ) _z (P ₂ O ₇ ) _w Wherein x is more than or equal to 2 and less than or equal to 4, y is more than or equal to 1 and less than or equal to 4, z is more than or equal to 0 and less than or equal to 4, W is more than or equal to 0 and less than or equal to 1, M comprises any one or combination of at least two of Ti, V, Cr, Mn, Fe, Co, Ni, Cu or Zn, A comprises any one or combination of at least two of Al, Si, P, S, Ti, V or W, and M is an electroactive transition metal;

preferably, the chemical formula of the Prussian blue cathode material is A _x M[Fe(CN) ₆ ] _y ·zH ₂ O, wherein, 0<x<2，0<y<1, A comprises any one or more of Li, Na or KAt least two of the components are combined, and M comprises any one or the combination of at least two of Fe, Mn, Co, Ni or Cu.

6. The positive electrode plate of the sodium-ion battery according to any one of claims 1 to 5, wherein the sodium-ion solid electrolyte comprises Na-beta-Al ₂ O ₃ 、Na ₃ PS ₄ 、Na ₃ SbS ₄ Or Na ₁₁ Sn ₂ PS ₁₂ Any one or a combination of at least two of them;

preferably, the conductive agent comprises any one of acetylene black, Super-P, carbon nanotubes, carbon fibers, Ketjen black, a graphite conductive agent or graphene or a combination of at least two of the acetylene black, the Super-P, the carbon nanotubes, the carbon fibers, the Ketjen black, the graphite conductive agent or the graphene;

preferably, the mass fraction of the sodium ion active material is 55 to 90%, preferably 70 to 85%, based on 100% by mass of the active material layer;

preferably, the mass fraction of the conductive agent is 0.1-5%, preferably 1-2.5%;

preferably, the mass fraction of the fibrillatable polymer is 0.1 to 5%, preferably 0.5 to 3%.

7. The preparation method of the positive pole piece of the sodium-ion battery as claimed in any one of claims 1 to 6, characterized by comprising the following steps:

(1) carrying out sodium ion exchange treatment on the fibrillatable polymer, and stirring and mixing the sodium ion positive electrode active substance, the solid electrolyte particles, the conductive agent and the fibrillatable polymer to obtain a mixture;

(2) mixing the mixture obtained in the step (1) at a high speed, and performing shearing and hot pressing treatment to obtain a positive active material layer;

(3) and (3) laminating the positive active material obtained in the step (2) on the surface of a current collector to obtain the positive pole piece of the sodium-ion battery.

8. The method of claim 7, wherein the sodium ion exchange treatment comprises the steps of:

(A) mixing and soaking a fibrillatable polymer and a hydrochloric acid solution, and washing to be neutral;

(B) and (2) drying the polymer obtained in the step (1), sieving, mixing with a sodium chloride solution, and washing and drying to obtain the fibrillatable polymer containing sodium ions.

9. The method of claim 7 or 8, wherein the high speed mixing is at a speed of 500 to 3000 rpm;

preferably, the high-speed mixing time is 10-60 min;

preferably, the temperature of the hot pressing treatment is 50-220 ℃.

10. A sodium-ion solid-state battery comprising the positive electrode sheet of the sodium-ion battery according to any one of claims 1 to 7.

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