CN115132961A - Positive pole piece of sodium-ion battery and preparation method and application thereof - Google Patents

Positive pole piece of sodium-ion battery and preparation method and application thereof Download PDF

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CN115132961A
CN115132961A CN202210743116.9A CN202210743116A CN115132961A CN 115132961 A CN115132961 A CN 115132961A CN 202210743116 A CN202210743116 A CN 202210743116A CN 115132961 A CN115132961 A CN 115132961A
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sodium
polymer
ion
ion battery
positive electrode
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陈少杰
李瑞杰
张琪
袁文森
王志文
曹晓菊
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Svolt Energy Technology Wuxi Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/137—Electrodes based on electro-active polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1399—Processes of manufacture of electrodes based on electro-active polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers

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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

Positive pole piece of sodium-ion battery and preparation method and application thereof
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
A sodium ion battery is a rocking chair type secondary battery similar to a lithium ion battery. Compared with a lithium ion battery, the first ionization energy of sodium ions is lower, so that the sodium ions are more stable, dendrite is not easy to separate out at low temperature, and more excellent safety, stability and low-temperature performance are brought to the sodium ion battery. And secondly, the molar conductivity of sodium ions is higher, and the electrochemical performance of the sodium ion battery is slightly superior to that of a lithium ion battery. The sodium resource supply and demand relationship is stable, and the price fluctuation is small. The sodium ion solid-state battery is a battery technology, and adopts non-flammable sodium ion solid-state battery electrolyte to replace flammable organic liquid electrolyte, so that the safety of a battery system is greatly improved, high-energy positive and negative electrodes can be better adapted, the weight of the system is reduced, and the synchronous improvement of energy density is realized.
At present, a solid positive pole piece in a sodium ion solid-state battery is generally manufactured by adopting a homogenizing and coating process, and in order to ensure that an electrolyte membrane can be continuous, a binder, a solvent and solid electrolyte particles need to be mixed in a homogenizing step.
CN114023921A discloses a positive pole piece of a sodium-ion battery and a preparation method and application thereof, wherein an active material of the positive pole piece of the sodium-ion battery comprises polytriphenylamine and/or polytriphenylamine derivatives, the polytriphenylamine and/or polytriphenylamine derivatives are used as a positive active material, the polytriphenylamine and the derivatives thereof have a rapid charge-discharge transmission framework of a poly-p-phenylene conductive polymer and show excellent power characteristics, and simultaneously have high-energy redox groups of polyaniline and have higher energy density.
CN110429329A discloses a preparation method of an all-solid-state sodium ion battery, which comprises the following steps: mixing sodium salt, an organic solvent, an additive and an initiator to obtain a liquid mixed solution; coating the surface of the positive pole piece and/or the negative pole piece to form a solid electrolyte layer; packaging to obtain a sodium ion battery cell; baking the sodium ion battery cell, injecting a liquid mixed solution, and standing; heating the sodium ion battery cell to obtain an unactivated solid sodium ion battery; and (3) carrying out formation, degassing and vacuum packaging on the solid sodium ion battery to obtain the all-solid sodium ion battery.
The sodium ion batteries in the scheme adopt the conventional binder, the used binder has no ionic conductivity, and after the binder is dissolved in a solvent and dried, the binder can be coated on the particle surfaces of solid electrolytes, so that ions are not smoothly transmitted among particles, the ionic conductivity of a solid positive pole piece is remarkably reduced, and the rate capability and the capacity performance of the battery are seriously lost. The binder can be coated on the particle surface of the solid electrolyte, so that the use amount of the binder is increased; in addition, the addition of the solvent increases the processes of drying, solvent recovery treatment and the like, increases the cost and may cause environmental pollution.
Disclosure of Invention
The invention aims to provide a positive pole piece of a sodium-ion battery, a preparation method and application thereof.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the invention provides a positive electrode plate of a sodium-ion battery, which comprises 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 - 。
The fibrillatable polymers of the present invention are, in part: from- [ CF 2 -CF 2 ] n A main chain structure of constituents providing the adhesive power and fiberizability properties of the polymer, another part consisting of Na + Ion exchange functional group-SO 3 H is a branch formed by Na + Formation of-SO after ion exchange 3 Na, which plays a role of conducting sodium ions.
The polymer which can be fiberized and can conduct sodium ions is used as the binder, the polymer can be connected between particles in a part of the positive electrode active layer and can also be connected between particles in the whole positive electrode active layer, the solid electrolyte particles are connected through the threadlike fiberizable polymer, the fiberizable polymer and the solid electrolyte particles are in point-to-point contact, the ion transmission impedance among the solid electrolyte particles can be effectively reduced, the ion transmission impedance among the positive electrode plate particles is reduced, and the mechanical property is improved. The solid battery prepared by the method has excellent rate performance, and the using amount of the binder is greatly reduced.
The polymer with the ion conduction function is used as the binder, the particles are bonded, and the sodium ion conduction function can be realized among the particles.
Preferably, the compound isThe conductivity of the fibrillated polymer is more than 5 x 10 -6 S/cm, for example: 5.2X 10 -6 S/cm、6×10 - 6 S/cm、7×10 -6 S/cm、8×10 -6 S/cm、9×10 -6 S/cm or 10X 10 -6 S/cm, etc.
Preferably, the fiberizable polymer is in the form of filaments.
According to the invention, the filamentous polymer is used as the binder, and no solvent is involved, so that on one hand, the contact and reaction of the solvent to the solid electrolyte are avoided, the impedance of the battery is reduced, and the rate capability of the battery is improved; on the other hand, the energy required by solvent evaporation and recovery is reduced, the problems of post-treatment and recovery of the organic solvent and the like are avoided, the production cost is effectively saved, and the environmental pollution is avoided; meanwhile, the preparation process is simple and easy to amplify, is a method suitable for industrial application, is beneficial to promoting the development of new energy industry, and has wide application prospect.
Preferably, there is point-to-point contact between the fibrillatable 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, 200 μm, or the like.
Preferably, the thickness of the current collector is < 20 μm.
Preferably, the sodium ion active material includes any one of a layered oxide material, a polyanionic positive electrode material, or a prussian blue positive electrode material, or a combination of at least two thereof.
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 the combination of at least two of Ti, V, Cr, Mn, Fe, Co, Ni, Cu or Zn, A comprises any one or at least one of Al, Si, P, S, Ti, V or WIn combination of the two, 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 combination of at least two of Li, Na or K, and M comprises any one or combination of at least two of Fe, Mn, Co, Ni or Cu.
Preferably, 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 includes any one of acetylene black, Super-P, carbon nanotube, carbon fiber (VGCF), ketjen black, graphite conductive agent, or graphene or a combination of at least two thereof.
Preferably, the mass fraction of the sodium ion active material is 55 to 90% based on 100% by mass of the active material layer, for example: 55%, 60%, 70%, 80%, 90%, etc., preferably 70 to 85%.
Preferably, the mass fraction of the conductive agent is 0.1-5%, such as: 0.1%, 0.5%, 1%, 3%, or 5%, etc., preferably 1 to 2.5%.
Preferably, the mass fraction of the fibrillatable polymer is 0.1 to 5%, for example: 0.1%, 0.5%, 1%, 3%, or 5%, etc., preferably 0.5 to 3%.
In a second aspect, the invention provides a method for preparing the positive electrode plate of the sodium-ion battery according to the first aspect, wherein the method for preparing the positive electrode plate of the sodium-ion battery comprises 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) shearing and hot-pressing the mixture obtained in the step (1) 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.
The invention adopts fiberizable polymer as the binder, and firstly mixes the sodium ion active substance, the sodium ion solid electrolyte and the conductive agent under the condition of not adding solvent; secondly, uniformly mixing the fiberizable polymer and the mixed particles at a low speed, and then carrying out high-speed shearing and mixing, wherein the fiberizable polymer is elongated, thinned and filamentized by utilizing the characteristic that the fiberizable polymer can be filamentized under the action of external shearing force, and the filamentized fiberizable polymer has viscosity and can bond the particles together; and because the fiberizable polymer exists in a filament shape after being filamentized, the fiberizable polymer is in point-point contact between solid electrolyte particles, and is different from the surface-surface contact between the binder and the particles in the traditional wet coating process.
The invention carries out shearing and hot pressing treatment on the mixture, thereby achieving the purposes of thinning the solid positive pole piece and homogenizing the thickness, forming a self-supporting independent positive pole piece after hot pressing, and finally compounding the positive pole piece and the current collector by hot pressing. The positive pole piece prepared by the process has good ductility and strong plasticity, can reach higher compaction density through repeated rolling, can effectively improve the volume energy density and the mass energy density of the battery, has no requirements on the shape and the size of the positive pole piece, can be changed and customized according to actual requirements, and has higher flexibility.
Preferably, the sodium ion exchange treatment comprises the following steps:
(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.
Taking PTFE as an example, the ion exchange steps are as follows:
Figure BDA0003715903160000061
the polymer prepared as described above was characterised using FTIR and it can be seen that it is at 1130cm -1 、1200cm -1 Presence of [ CF ] in the vicinity 2 -CF 2 ] n Absorption peak of the segment group and at 1060cm -1 In the presence of-SO 3 - Absorption peak of group.
Preferably, the speed of the high-speed mixing is 500-3000 rpm, for example: 500rpm, 1000rpm, 2000rpm, 2500rpm, 3000rpm, or the like.
In the invention, if the rotating speed is too low and the time is too short, the external mechanical force is not enough to stretch the adhesive to be in a filiform state, so that the adhesive cannot reach the optimal bonding state; if the rotation speed is too high and the rotation time is too long, the excessive applied mechanical force can cause the adhesive to be excessively stretched and prolonged to break, so that the adhesive forms short and small segmented filaments, and finally the adhesive force is reduced.
Preferably, the time of the high-speed mixing is 10-60 min, such as: 10min, 20min, 30min, 40min, 50min or 60min and the like.
Preferably, the temperature of the hot pressing treatment is 50-220 ℃, for example: 50 ℃, 80 ℃, 100 ℃, 200 ℃, 220 ℃ or the like.
In a third aspect, the present invention provides a sodium ion solid-state battery, which comprises the positive electrode plate of the sodium ion battery according to the first aspect.
Compared with the prior art, the invention has the following beneficial effects:
(1) the positive pole piece of the invention takes polymer which can be fiberized and can conduct sodium ions as the binder. Compared with the traditional wet coating process, the method does not need the participation of a solvent; and the solid electrolyte particles are connected through the filamentous fiberizable polymer, the fiberizable polymer is in point-to-point contact with the solid electrolyte particles, the ion transmission impedance among the solid electrolyte particles can be effectively reduced, the ion transmission impedance among the positive electrode plate particles is reduced, and the mechanical property is improved. The solid battery prepared by the method has excellent rate performance, and the using amount of the binder is greatly reduced.
(2) The polymer with the ionic conduction function is used as the binder, the particles are bonded, and the sodium ions can be conducted among the particles, so that 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, and the solid-state battery prepared by the method has excellent rate performance.
(3) The tensile strength of the positive pole piece of the sodium-ion battery can reach 115.2N/cm 2 More than, the 0.33C specific discharge capacity can reach more than 93.8mAh/g, the 1C specific discharge capacity can reach more than 90mAh/g, the 3C specific discharge 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%.
Drawings
Fig. 1 is an SEM image of the positive electrode sheet of the sodium-ion battery described in example 1.
FIG. 2 is an FTIR spectrum of a fiberizable polymer after sodium ion exchange.
Detailed Description
The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.
The sodium ion exchange process for the fibrillatable polymers used in the examples and comparative examples of the invention is as follows:
1) firstly, 10g of the polymer is soaked for 32 hours by using 100ml of 5mol/L HCl solution;
2) after soaking, washing the polymer by using excessive deionized water until the pH value is neutral;
3) drying the polymer obtained in the step 2 at 120 ℃ for 8 h;
4) screening the polymer particles in the step 3 by using a 300-mesh ultrasonic vibration sieve, and taking the material on the lower layer of the sieve for later use;
5) dissolving NaCl in deionized water with the mass concentration of 30%;
6) mixing 2g of the polymer particles obtained in the step 4 with 50ml of the solution obtained in the step 5, and stirring at the rotating speed of 1200rpm for 30 hours at the temperature of 60 ℃;
7) washing the polymer obtained in the step 6 by using deionized water until the surface has no NaCl residue;
8) the polymer obtained in step 7 was dried at 120 ℃ for 8h and the FTIR spectrum of the prepared polymer is shown in FIG. 2.
Example 1
The embodiment provides a positive pole piece of a sodium-ion battery, and a preparation method of the positive pole piece of the sodium-ion battery comprises the following steps:
(1) mixing Na 3 V 2 (PO 4 ) 3 、Na 3 PS 4 Putting the mixture and Super-P into a stirrer, wherein the ratio of the materials is 75:23:2, stirring at a stirring speed of 350rpm for 60min to obtain a mixture, adding the mixture and a fibrillatable polymer subjected to sodium ion exchange into the stirrer together for low-speed stirring and mixing, wherein the ratio of the polymer to the mixed material is 2:98, the stirring speed is 300rpm, and the stirring time is 20min to obtain a mixed material;
(2) shearing and mixing the mixture by using a high-speed mixer to obtain a sheared mixture, wherein the high-speed stirring rotating speed is 2500rpm, the stirring time is 40min, and the sheared mixture is placed into a roller press to be subjected to hot pressing treatment to form a self-supporting positive electrode active material layer, wherein the hot pressing temperature is 60 ℃, the rolling speed is 50cm/min, and the thickness of the positive electrode active material layer is 60 mu m;
(3) and hot-pressing the positive active material layer and the aluminum foil together to obtain the positive pole piece of the sodium-ion battery.
The SEM image of the positive electrode sheet is shown in fig. 1, wherein the particles are solid electrolyte particles, the filaments are filamentous polymers, and point-to-point contact between the filamentous polymers and the solid electrolyte particles can be seen at the circles.
Example 2
The embodiment provides a positive pole piece of a sodium-ion battery, and a preparation method of the positive pole piece of the sodium-ion battery comprises the following steps:
(1) na is mixed with 3 V 2 (PO 4 ) 3 、Na 3 SbS 4 Putting VGCF and VGCF into a stirrer, wherein the ratio of the substances is 80:19:1, stirring at a stirring speed of 400rpm for 80min to obtain a mixture, adding the mixture and the fiberizable polymer subjected to sodium ion exchange into the stirrer together for low-speed stirring and mixing, wherein the ratio of the polymer to the mixed material is 1:99, the stirring speed is 400rpm, and the stirring time is 20min to obtain a mixture;
(2) shearing and mixing the mixture by using a high-speed mixer to obtain a sheared mixture, wherein the high-speed stirring rotating speed is 3000rpm, the stirring time is 40min, and the sheared mixture is placed into a roller press to be subjected to hot pressing treatment to form a self-supporting positive electrode active material layer, wherein the hot pressing temperature is 80 ℃, the rolling speed is 60cm/min, and the thickness of the positive electrode active material layer is 60 mu m;
(3) and hot-pressing the positive active material layer and the aluminum foil together to obtain the positive pole piece of the sodium-ion battery.
Example 3
This example differs from example 1 only in that the polymer to blend ratio is 0.5:99.5, and the other conditions and parameters are exactly the same as in example 1.
Example 4
This example differs from example 1 only in that the ratio of polymer to blend was 3.5:96.5, and the other conditions and parameters were exactly the same as in example 1.
Comparative example 1
The comparative example provides a preparation method of a sodium ion positive pole piece, which comprises the following steps:
(1) mixing Na 3 V 2 (PO 4 ) 3 、Na 3 PS 4 Putting the SP and the mixture into a stirrer, wherein the ratio of the substances is 75:23:2, and stirring at the stirring speed of 350rpm for 60min to obtain a mixture;
(2) dissolving nitrile rubber accounting for 2 percent of the mass of the whole powder with a toluene solvent;
(3) homogenizing the slurry dissolved in the step (2) and the mixed slurry in the step (1) by using a homogenizer;
(4) and finally, coating the slurry by using a coating machine at a coating speed of 1m/min, and drying at 90 ℃ for 2h after coating to prepare the positive pole piece, wherein the thickness of the positive pole piece is 60 microns.
Comparative example 2
The comparative example provides a preparation method of a positive pole piece of a sodium ion all-solid-state battery, which comprises the following steps:
(1) mixing Na 3 V 2 (PO 4 ) 3 、Na 3 SbS 4 Putting VGCF and VGCF into a stirrer, wherein the ratio of the above substances is 80:19:1, and stirring at 400rpm for 80min to obtain a mixture;
(2) dissolving nitrile rubber accounting for 5 percent of the mass of the whole powder with a toluene solvent;
(3) homogenizing the slurry dissolved in the step (2) and the mixed slurry in the step (1) by using a homogenizer;
(4) and finally, coating the slurry by using a coating machine at a coating speed of 1m/min, and drying at 90 ℃ for 2h after coating to prepare the positive pole piece, wherein the thickness of the positive pole piece is 60 microns.
Comparative example 3
This comparative example differs from example 1 only in that the sodium ion exchange treatment was not carried out on the polymer and the other conditions and parameters were exactly the same as in example 1.
And (3) performance testing:
the conductivity of each of the materials of example 1 and comparative example 1 was tested and the results are shown in table 1:
TABLE 1
Figure BDA0003715903160000111
As can be seen from table 1, since the polymer having sodium ion conductivity in the present invention was used as a binder, the sample "No. 2" had higher sodium ion conductivity than the sample "No. 3" and also was closer to the conductivity of the original sample "No. 1", that is, the sodium ion conduction resistance between particles was smaller. The samples "No. 2" and "No. 3" had higher conductivity than the sample "No. 4" due to the use of the binder having fiberizing ability.
The positive electrode sheets obtained in examples 1 to 4 and comparative examples 1 to 3 were subjected to tensile strength test, the positive electrode sheets obtained above were cut into 10 mm-diameter circular sheets by a microtome, and 200mg of Na ion as a solid electrolyte Na was added 3 PS 4 Using metal Na as a negative electrode, a positive electrode sheet and a sodium sheet were placed on both sides of the solid electrolyte sheet prepared in step 2, respectively, and molded after applying a pressure of 50MPa, and the above-described battery was subjected to charge and discharge tests at a rate of 0.33C, 1C, and 3C, with the test results shown in table 1:
TABLE 1
Figure BDA0003715903160000121
As can be seen from Table 1, the tensile strength of the positive pole piece of the sodium-ion battery can reach 115.2N/cm in the examples 1-2 2 More than, the 0.33C specific discharge capacity can reach more than 102.8mAh/g, the 1C specific discharge capacity can reach more than 93.8mAh/g, the 3C specific discharge 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%.
Compared with the embodiment 1 and the embodiment 3-4, the additive amount of the fiberizable polymer in the positive pole piece of the sodium-ion battery can influence the performance of the prepared positive pole piece, and the additive amount of the fiberizable polymer is controlled to be 0.5-3%, so that the prepared positive pole piece has better performance. If the addition amount of the fiberizable polymer is too large, the addition of too much polymer with low ionic conductivity can still obstruct the ion transmission, thereby causing the reduction of the rate doubling performance; if the addition amount of the fiberizable polymer is too small, the cohesive force is insufficient, the performance of the pole piece model is poor, the film cannot be formed, the contact among particles is not tight, and the electrical performance is reduced.
Compared with the embodiment 1 and the comparative example 1, and the embodiment 2 and the comparative example 2, the invention connects the solid electrolyte particles through the filamentous fiberizable polymer, and the fiberizable polymer and the solid electrolyte particles are in point-to-point contact, thereby effectively reducing the ion transmission impedance among the solid electrolyte particles, reducing the ion transmission impedance among the positive electrode plate particles and improving the mechanical property. The polymer with the ion conduction function is used as the binder, the particles are bonded, and the sodium ion conduction function can be realized among the particles.
Compared with the comparative example 3, the method disclosed by the invention has the advantages that the sodium ion exchange treatment is carried out on the fiberizable polymer, so that the polymer has certain sodium ion transmission capacity, the barrier effect of the polymer on the ion transmission is further reduced, and the capacity exertion and the rate capability of the pole piece are improved.
The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the scope and disclosure 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.
CN202210743116.9A 2022-06-27 2022-06-27 Positive pole piece of sodium-ion battery and preparation method and application thereof Pending CN115132961A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115395090A (en) * 2022-10-10 2022-11-25 蜂巢能源科技(无锡)有限公司 Solid electrolyte membrane and preparation method and application thereof
CN116314598A (en) * 2023-05-26 2023-06-23 江苏正力新能电池技术有限公司 Dry electrode slice and preparation method and application thereof

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115395090A (en) * 2022-10-10 2022-11-25 蜂巢能源科技(无锡)有限公司 Solid electrolyte membrane and preparation method and application thereof
CN116314598A (en) * 2023-05-26 2023-06-23 江苏正力新能电池技术有限公司 Dry electrode slice and preparation method and application thereof
CN116314598B (en) * 2023-05-26 2023-09-08 江苏正力新能电池技术有限公司 Dry electrode slice and preparation method and application thereof

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