CN110416627B

CN110416627B - PFSA-Na solid composite electrolyte membrane and preparation method and application thereof

Info

Publication number: CN110416627B
Application number: CN201910736151.6A
Authority: CN
Inventors: 徐茂文; 杜光远; 陶梦丽
Original assignee: Southwest University
Current assignee: Southwest University
Priority date: 2019-08-09
Filing date: 2019-08-09
Publication date: 2021-03-16
Anticipated expiration: 2039-08-09
Also published as: CN110416627A

Abstract

The invention relates to a PFSA-Na solid composite electrolyte diaphragm and a preparation method and application thereof, belonging to the technical field of battery materials, wherein the preparation method of the diaphragm mainly comprises the following steps: firstly, PFSA-Li powder and a sodium source are used as raw materials to prepare PFSA-Na powder through ion exchange reaction, then the PFSA-Na powder is dissolved in an organic solvent to obtain PFSA-Na glue solution, electrolyte is added into the glue solution under stirring to obtain mixed solution, and finally the mixed solution is subjected to blade coating and drying to obtain the PFSA-Na solid composite electrolyte membrane. The diaphragm prepared by the method has thinner thickness, is beneficial to thinning the thickness of the battery in the commercial process and improving the energy density, and can effectively improve the cycle stability of the battery when being used in a secondary solid-state sodium ion battery. In addition, the battery assembled by the diaphragm can still normally work at minus dozens of degrees. The method is simple and easy to operate, has low requirements on equipment, and is suitable for expanded production.

Description

PFSA-Na solid composite electrolyte membrane and preparation method and application thereof

Technical Field

The invention belongs to the technical field of battery materials, and particularly relates to a PFSA-Na solid-state composite electrolyte diaphragm and a preparation method and application thereof.

Background

The rechargeable battery is a basic power technology for storing energy of electric vehicles and power grids, and popularization and application of the technology can reduce pollution of fossil fuel to the environment, avoid intermittence of green energy sources such as wind energy, solar energy and the like, and provide convenience for life and development of human society. Therefore, there is a strong need to search for and find an energy storage system that can supplement existing high energy density, long cycle life Lithium Ion Batteries (LIBs). In recent years, the cost of lithium ion batteries has been increasing due to the small global reserve of lithium resources. Sodium and lithium are located in the same main group of the periodic table of elements, sodium-ion batteries and lithium-ion batteries have the same electrochemical behavior, and the earth reserves of sodium are rich and low in cost, so that the sodium-ion batteries become the most promising substitutes for the lithium-ion batteries.

In recent years, safety accidents and casualties caused by explosion of lithium ion batteries are frequent, and the basic reason is that organic electrolyte used by the traditional liquid battery has thermal instability, is volatile and highly flammable, can be electrochemically decomposed in the battery circulation process to cause battery expansion, and can cause liquid leakage seriously to further cause fire explosion accidents. The same potential safety hazard brought by organic electrolyte is faced in the sodium ion battery and the lithium ion battery, so that the solid electrolyte is used for replacing the organic electrolyte.

Disclosure of Invention

In view of the above, an object of the present invention is to provide a method for preparing a PFSA-Na solid composite electrolyte membrane; the second purpose is to provide a PFSA-Na solid composite electrolyte diaphragm; the other purpose is to provide the application of the PFSA-Na solid composite electrolyte membrane in a secondary solid sodium-ion battery.

In order to achieve the purpose, the invention provides the following technical scheme:

1. a preparation method of a PFSA-Na solid-state composite electrolyte membrane comprises the following steps:

adding PFSA-Li powder and a sodium source into water, uniformly mixing, stirring for 5-24h at 40-150 ℃, then centrifugally washing and drying to obtain PFSA-Na powder, dissolving the PFSA-Na powder in an organic solvent to obtain PFSA-Na glue solution, adding an electrolyte into the PFSA-Na glue solution under stirring to obtain a mixed solution, finally blade-coating the mixed solution, and drying at 60-150 ℃ for 12-48h to obtain the PFSA-Na solid composite electrolyte membrane.

Preferably, the mass ratio of the PFSA-Li powder to the sodium source is 1-100: 1-400.

Preferably, the mass fraction of PFSA-Na powder in the PFSA-Na glue solution is 20-40%; the volume ratio of the PFSA-Na glue solution to the electrolyte is 0.5-200: 1; the concentration of the electrolyte is 1 mol/L.

Preferably, the sodium source is one of sodium chloride, sodium acetate, sodium nitrate, sodium hydroxide or sodium carbonate.

Preferably, the centrifugal washing is performed 3-10 times at the speed of 5000-9000r/min by using deionized water, and each time is performed for 3-5 min.

Preferably, the drying is specifically drying for 5-96h at 30-150 ℃.

Preferably, the organic solvent is one of nitrogen-nitrogen dimethylformamide, N-methylpyrrolidone, acetonitrile, tetrahydrofuran or dimethyl sulfoxide.

Preferably, the solute in the electrolyte is one of sodium perchlorate, sodium hexafluorophosphate, sodium trifluoromethanesulfonate and sodium bistrifluoromethylsulfonyl imide, and the solvent in the electrolyte is one of EC/DEC, EC/PC, DGM or DME.

2. The PFSA-Na solid composite electrolyte membrane prepared by the method.

3. The PFSA-Na solid composite electrolyte membrane is applied to a secondary solid sodium-ion battery.

The invention has the beneficial effects that: the invention provides a PFSA-Na solid composite electrolyte diaphragm and a preparation method and application thereof, wherein PFSA-Li powder and a sodium source are used as raw materials, PFSA-Na powder is prepared through ion exchange reaction, PFSA-Na powder is dissolved in an organic solvent to obtain PFSA-Na powder glue solution, electrolyte is added into the glue solution, the viscosity of finally formed mixed solution can be controlled by reasonably controlling the mass fraction of the PFSA-Na powder in the glue solution and the volume ratio of the glue solution to the electrolyte, and the thickness of the solid composite electrolyte diaphragm formed by blade coating at the later stage is ensured; by controlling the types of solute and solvent in the electrolyte and the drying temperature and time after blade coating, on one hand, the content of free sodium ions in the finally prepared solid-state composite electrolyte diaphragm can be improved by utilizing the specific solute in the electrolyte, so that the ionic conductivity is improved, and on the other hand, the crystallinity of a polymer matrix (PFSA) in the drying film-forming process can be reduced by utilizing the specific solvent in the electrolyte, so that the vibration of a molecular chain segment is improved, and the ionic conductivity is further improved. If the drying temperature after blade coating is too high, the electrolyte is caused to generate adverse effects such as pyrolysis and the like, so that the content of free sodium ions in the finally prepared solid composite electrolyte diaphragm cannot be improved, and if the drying time is too short, the drying is incomplete, so that the toughness of the finally prepared solid composite electrolyte diaphragm is affected. The diaphragm prepared by the method disclosed by the invention is thinner, the thickness of the battery is reduced in a commercial process, the energy density is improved, and the cycling stability of the battery can be effectively improved when the diaphragm is used in a secondary solid-state sodium ion battery. In addition, the battery assembled by the diaphragm can still normally work at minus dozens of degrees. The method is simple and easy to operate, has low requirements on equipment, and is suitable for expanded production.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the means of the instrumentalities and combinations particularly pointed out hereinafter.

Drawings

For the purposes of promoting a better understanding of the objects, aspects and advantages of the invention, reference will now be made to the following detailed description taken in conjunction with the accompanying drawings in which:

fig. 1 is a morphology diagram of a PFSA-Na solid state composite electrolyte membrane prepared in example 1;

fig. 2 is a graph showing the results of an ion conductivity test of the PFSA-Na solid composite electrolyte membrane prepared in example 1 and a pure PFSA-Na solid electrolyte membrane prepared in comparative example 1; (in FIG. 2, a is the result of an ionic conductivity test of the PFSA-Na solid state composite electrolyte membrane prepared in example 1, and in FIG. 2, b is the result of an ionic conductivity test of the pure PFSA-Na solid state electrolyte membrane prepared in comparative example 1)

Fig. 3 is a graph showing the results of an ion conductivity test of the PFSA-Na solid state composite electrolyte separator prepared in example 2;

fig. 4 is a graph showing the results of an ion conductivity test of the PFSA-Na solid state composite electrolyte separator prepared in example 3;

fig. 5 is a graph showing the results of an ion conductivity test of the PFSA-Na solid state composite electrolyte separator prepared in example 4;

FIG. 6 is a graph showing the results of electrochemical performance tests on a sodium ion battery of example 6, which consists of a positive electrode sheet containing NVP @ C, and the PFSA-Na solid-state composite electrolyte membrane prepared in example 1; (a in FIG. 6 is a charge-discharge curve diagram of the battery during the cycle, and b in FIG. 6 is a cycle performance diagram of the battery)

Fig. 7 is a graph showing the results of electrochemical performance tests on a sodium ion battery of example 6, which consists of a positive electrode sheet containing NFP @ C, and the PFSA-Na solid-state composite electrolyte separator prepared in example 1; (a in fig. 7 is a charge-discharge curve chart of the battery in the cycle process, and b in fig. 7 is a cycle performance chart of the battery);

fig. 8 is a graph showing the results of electrochemical performance tests on a sodium ion battery in example 6, which consists of a positive electrode sheet containing NMVP @ C, and the PFSA-Na solid-state composite electrolyte membrane prepared in example 1; (a in fig. 8 is a charge-discharge curve chart of the battery in the cycle process, and b in fig. 8 is a cycle performance chart of the battery);

fig. 9 is a graph showing the results of electrochemical performance tests of the sodium ion battery of example 6, which is composed of the positive electrode sheet containing HQ-NaFe, and the PFSA-Na solid-state composite electrolyte separator prepared in example 1; (a in fig. 9 is a charge-discharge curve diagram of the battery during the cycle, and b in fig. 9 is a cycle performance diagram of the battery);

fig. 10 is a graph of the results of the performance test of the sodium-ion battery assembled based on the PFSA-Na solid-state composite electrolyte separator in example 7 at low temperature.

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.

Example 1

Preparation of PFSA-Na solid composite electrolyte membrane

PFSA-Li powder and sodium hydroxide are added into water according to the mass ratio of 1:150 to be mixed uniformly, the mixture is stirred for 5h at 50 ℃, then the mixture is centrifugally washed for 3 times by deionized water at the speed of 9000r/min, each time of centrifugal washing is 5min, then the mixture is dried for 96h at 120 ℃ to obtain PFSA-Na powder, the PFSA-Na powder is dissolved in dimethyl sulfoxide to obtain PFSA-Na glue solution, the volume ratio of the PFSA-Na glue solution to electrolyte is 40:1, electrolyte is added into the PFSA-Na glue solution under stirring to obtain mixed solution, finally the mixed solution is subjected to blade coating and dried for 48h at 80 ℃ to obtain the PFSA-Na solid composite electrolyte diaphragm with the thickness of 20 mu m, wherein the mass fraction of the PFSA-Na powder in the PFSA-Na glue solution is 20%, the solute in the electrolyte is sodium perchlorate, and the solvent is EC/DEC, the concentration of the electrolyte was 1 mol/L. The morphology of the PFSA-Na solid-state composite electrolyte membrane is shown in figure 1.

Example 2

Preparation of PFSA-Na solid composite electrolyte membrane

PFSA-Li powder and sodium carbonate are added into water according to the mass ratio of 1:400 and mixed evenly, stirring at 80 deg.C for 10h, centrifuging at 7000r/min with deionized water for 10 times, each time for 3min, then drying for 5h at 150 ℃ to obtain PFSA-Na powder, dissolving the PFSA-Na powder in acetonitrile to obtain PFSA-Na glue solution, wherein the volume ratio of the PFSA-Na glue solution to the electrolyte is 200:1, adding electrolyte into the PFSA-Na glue solution under stirring to obtain mixed solution, blade-coating the mixed solution, drying at 150 deg.C for 12h to obtain PFSA-Na solid composite electrolyte membrane with thickness of 40 μm, wherein, the mass fraction of PFSA-Na powder in the PFSA-Na glue solution is 40%, the solute in the electrolyte is sodium hexafluorophosphate, the solvent is DME, and the concentration of the electrolyte is 1 mol/L.

Example 3

Preparation of PFSA-Na solid composite electrolyte membrane

PFSA-Li powder and sodium chloride are added into water according to the mass ratio of 100:1 to be mixed uniformly, stirred for 24 hours at 150 ℃, then centrifugally washed for 7 times by deionized water at the speed of 5000r/min, each time centrifugally washed for 3min, then dried for 36 hours at 60 ℃ to obtain PFSA-Na powder, the PFSA-Na powder is dissolved in N-methylpyrrolidone to obtain PFSA-Na glue solution, electrolyte is added into the PFSA-Na glue solution under stirring according to the volume ratio of the PFSA-Na glue solution to the electrolyte of 0.5:1 to obtain mixed solution, finally the mixed solution is subjected to blade coating and dried for 36 hours at 60 ℃ to obtain the PFSA-Na solid composite electrolyte diaphragm with the thickness of 20 mu m, wherein the mass fraction of the PFSA-Na powder in the PFSA-Na glue solution is 20%, the solute in the electrolyte is sodium trifluoromethanesulfonate, the solvent is EC/PC, and the concentration of the electrolyte is 1 mol/L.

Example 4

Preparation of PFSA-Na solid composite electrolyte membrane

PFSA-Li powder and sodium nitrate are added into water according to the mass ratio of 80:1 to be mixed evenly, the mixture is stirred for 2 hours at 120 ℃, then the mixture is centrifugally washed for 5 times by deionized water at the speed of 6000r/min, each time is centrifugally washed for 4 minutes, then the mixture is dried for 48 hours at 30 ℃ to obtain PFSA-Na powder, the PFSA-Na powder is dissolved in tetrahydrofuran to obtain PFSA-Na glue solution, the volume ratio of the PFSA-Na glue solution to electrolyte is 100:1, electrolyte is added into the PFSA-Na glue solution under stirring to obtain mixed solution, finally the mixed solution is subjected to blade coating and dried for 24 hours at 100 ℃ to obtain the PFSA-Na solid composite electrolyte diaphragm with the thickness of 30 mu m, wherein the mass fraction of the PFSA-Na powder in the PFSA-Na glue solution is 30 percent, the solute in the electrolyte is bis-trifluoromethyl sulfimide sodium, the solvent is DGM, and the concentration of the electrolyte is 1 mol/L.

Comparative example 1

The difference from example 1 is that PFSA-Na powder is dissolved in dimethyl sulfoxide to obtain PFSA-Na glue solution, and the PFSA-Na glue solution is directly subjected to blade coating and then dried at 80 ℃ for 48 hours to obtain a pure PFSA-Na solid electrolyte membrane.

Example 5

(1) The ionic conductivity of the PFSA-Na solid-state composite electrolyte membrane prepared in example 1 and the pure PFSA-Na solid-state electrolyte membrane prepared in comparative example 1 were tested

The PFSA-Na solid composite electrolyte membrane prepared in example 1 and the pure PFSA-Na solid electrolyte membrane prepared in comparative example 1 were respectively sandwiched between two stainless steel electrodes, respectively assembled into a CR2032 type battery, the test of the ac impedance spectrum was performed at room temperature using an electrochemical workstation, the test results are shown in figure 2, wherein a in FIG. 2 is an ionic conductivity test result of the PFSA-Na solid state composite electrolyte membrane prepared in example 1, b in fig. 2 is an ion conductivity test result of the pure PFSA-Na solid electrolyte membrane prepared in comparative example 1, and as can be seen from fig. 2, as can be seen from a and b in fig. 2, the resistance value of the PFSA-Na solid composite electrolyte membrane is significantly smaller than that of the pure PFSA-Na solid electrolyte membrane, therefore, the room-temperature ionic conductivity of the PFSA-Na solid-state composite electrolyte membrane is obviously higher than that of a pure PFSA-Na solid-state electrolyte membrane. The electrolyte is added in the process of preparing the PFSA-Na solid composite electrolyte diaphragm, the solute in the electrolyte increases the number of free sodium ions in the composite solid electrolyte diaphragm, and meanwhile, the solvent in the electrolyte has a plasticizing effect on the solid electrolyte diaphragm, so that the crystallinity of a polymer matrix can be reduced, partial molecular chain segments of the polymer matrix are more disordered, vibration and migration are more violent, and the finally prepared PFSA-Na solid composite electrolyte diaphragm has excellent room-temperature ionic conductivity.

(2) The ionic conductivity of the PFSA-Na solid state composite electrolyte separators prepared in examples 2 to 3 was tested

The PFSA-Na solid composite electrolyte membranes prepared in examples 2 to 3 were respectively sandwiched between two stainless steel electrodes to be assembled into CR2032 type cells, and ac impedance spectroscopy was performed at room temperature using an electrochemical workstation, and the results of the ac impedance spectroscopy are shown in fig. 3, 4 and 5 in sequence, where the intersection point of the curve and the abscissa in each figure can be regarded as the overall resistance (total resistance) of the membrane, i.e., R, as can be seen from fig. 3 to 5, the overall resistance of the PFSA-Na solid composite electrolyte membranes prepared in examples 2 to 3 was very low, and the PFSA-Na solid composite electrolyte membranes prepared in examples 2 to 3 had ideal room temperature ionic conductivity according to the formula δ ═ L/(R × S).

Example 6

Application of PFSA-Na solid-state composite electrolyte membrane prepared in example 1 to secondary solid-state sodium ion battery

(1) Preparation of four positive electrode materials of NVP @ C, NFP @ C, NMVP @ C and HQ-NaFe

Grinding sodium acetate, ammonium metavanadate, ammonium dihydrogen phosphate and a proper amount of sucrose in a stoichiometric ratio in an agate mortar for 10min, then adding 10mL of ethanol, continuously grinding until the ethanol is completely volatilized to obtain a powdery precursor, placing the powdery precursor in a tube furnace, heating to 700 ℃ at a heating rate of 5 ℃/min in an argon atmosphere, and carrying out heat preservation treatment for 6 hours to obtain the NVP @ C.

Mixing sodium acetate, ferric oxalate, sucrose, ammonium dihydrogen phosphate and a proper amount of ethanol according to a stoichiometric ratio, performing ball milling for 24h, drying a product obtained by ball milling at 60 ℃ for 3h to obtain precursor powder, and performing heat preservation treatment on the precursor powder at 600 ℃ for 12h at a heating rate of 3 ℃/min in an argon atmosphere to obtain NFP @ C.

Grinding and mixing sodium acetate, manganese acetate and vanadium acetylacetonate which accord with the stoichiometric ratio in an agate mortar for 10min to obtain mixed powder, adding phosphoric acid (14.63M) and 10mL of absolute ethyl alcohol which accord with the stoichiometric ratio into the mixed powder, continuously grinding and mixing until the ethyl alcohol is completely volatilized to obtain a powder precursor, placing the powder precursor in a tubular furnace, heating to 650 ℃ at the heating rate of 5 ℃/min under the protection of argon, and carrying out heat preservation treatment for 8h to obtain the NMVP @ C.

Firstly weighing 968mg of sodium ferrocyanide decahydrate, dissolving the sodium ferrocyanide decahydrate in 100mL of deionized water to obtain a clear solution, adding 1mL of hydrochloric acid (37%) into the clear solution under mechanical stirring, continuously stirring the solution at 60 ℃ for 4h, carrying out suction filtration and washing, and carrying out vacuum drying at 100 ℃ for 24h to obtain HQ-NaFe.

(2) Respectively mixing the NVP @ C, NFP @ C, NMVP @ C and HQ-NaFe positive electrode materials prepared in the step (1) with acetylene black and polyvinylidene fluoride according to a mass ratio of 70:20:10, adding a small amount of N-methyl pyrrolidone, grinding the mixture in an agate mortar to form uniform black paste, uniformly coating the obtained black paste positive electrode slurry on an aluminum foil with the diameter of 13mm, and performing vacuum drying at 120 ℃ for 12 hours to obtain four positive electrode sheets.

(3) The positive plate containing NVP @ C prepared in step (2), the PFSA-Na solid-state composite electrolyte membrane prepared in example 1, and sodium metal were transferred to a glove box filled with argon gas to assemble a solid sodium ion battery (coin cell), the model of the used coin cell was CR2032, after the assembly was completed, the battery was removed from the glove box, and then an electrochemical performance test was performed on a Land test system, the test voltage range was 1.5-4.0V, and the test result is shown in fig. 6, in which a in fig. 6 is a charge-discharge curve diagram of the battery in the cycle process, and b in fig. 6 is a charge-discharge curve diagram of the battery in the cycle processThe battery cycle performance diagram, as can be seen from a in fig. 6, when the NVP @ C and the PFSA-Na solid-state composite electrolyte membrane are assembled into a solid-state sodium-ion battery, a significant charge-discharge platform is provided, which is consistent with the electrochemical behavior exhibited in the common electrolyte. As can be seen from a in FIG. 6, the specific discharge capacity of the first ring of the battery reaches 106mAh g^-1The performance is excellent, the contact ratio of the charging and discharging curves of 50 circles, 100 circles and 200 circles is high, the polarization is small, and the reversibility of the battery in the circulating process is good. As can be seen from b in fig. 6, the battery has good cycle stability in the actual cycle process, the cycle life is as long as 200 cycles, the reversible capacity attenuation in the cycle process is reduced, and the coulombic efficiency in the cycle process is always close to 100%, which indicates that the electrochemical reaction involved in the cycle process has high reversibility, and further verifies that the PFSA-Na solid composite electrolyte membrane prepared in example 1 and the NVP @ C material have good matching performance in energy storage applications.

(4) The positive plate containing NFP @ C prepared in step (2), the PFSA-Na solid-state composite electrolyte membrane prepared in example 1, and sodium metal were transferred to a glove box filled with argon gas to assemble a solid-state sodium-ion battery (coin battery), the model of the coin battery used was CR2032, after the assembly was completed, the battery was removed from the glove box, then, the electrochemical performance test is carried out on a Land test system, the test voltage range is 1.5-4.0V, the test result is shown in figure 7, wherein a in fig. 7 is a charge-discharge curve diagram of the battery in the cycle process, b in fig. 7 is a cycle performance diagram of the battery, and as can be seen from a in fig. 7, when NFP @ C and PFSA-Na solid-state composite electrolyte membrane are assembled into a solid-state sodium ion battery, has obvious charge and discharge platform, which is consistent with the electrochemical behavior of the material in common electrolyte. As can be seen from a in FIG. 7, the charge-discharge specific capacity of the first ring of the battery reaches 126 mAh.g and 84 mAh.g^-1The performance is excellent, and the contact ratio of the charging and discharging curves of 50, 100 and 200 circles is higher, which shows that the battery has good reversibility in the circulating process. As can be seen from b in FIG. 7, the battery has good cycle stability in the actual cycle process, the cycle life is as long as 200 circles, the reversible capacity attenuation in the cycle process is reduced, and coulombs in the cycle processThe efficiency is always close to 100%, which shows that the involved electrochemical reaction in the circulation process has high reversibility, and further verifies that the PFSA-Na solid-state composite electrolyte membrane prepared in the example 1 has good matching performance with the NFP @ C material in energy storage application.

(5) The positive plate containing NMVP @ C prepared in step (2), the PFSA-Na solid-state composite electrolyte membrane prepared in example 1, and sodium metal were transferred to a glove box filled with argon gas to assemble a solid-state sodium-ion battery (coin cell) of the type CR2032, after the assembly was completed, the battery was removed from the glove box, then, the electrochemical performance test is carried out on a Land test system, the test voltage range is 2.5-3.8V, the test result is shown in figure 8, wherein, a in fig. 8 is a charge-discharge curve chart of the battery in the circulation process, b in fig. 8 is a circulation performance chart of the battery, and as can be seen from a in fig. 8, when the NMVP @ C and the PFSA-Na solid-state composite electrolyte membrane are assembled into the solid-state sodium ion battery, has obvious charge and discharge platform, which is consistent with the electrochemical behavior of the material in common electrolyte. As can be seen from a in FIG. 8, the charge-discharge specific capacity of the first ring of the battery reaches 101 mAh.g and 87 mAh.g^-1The performance is excellent, the contact ratio of charging and discharging curves of 50 circles, 100 circles and 193 circles is high, the polarization is small, and the reversibility of the battery in the circulating process is good. As can be seen from b in fig. 8, the battery has good cycle stability in the actual cycle process, the cycle life is as long as 200 cycles, the reversible capacity attenuation in the cycle process is reduced, and the coulombic efficiency in the cycle process is always close to 100%, which indicates that the electrochemical reaction involved in the cycle process has high reversibility, and further verifies that the PFSA-Na solid composite electrolyte membrane prepared in example 1 and the NMVP @ C material have good matching performance in energy storage applications.

(6) The positive plate containing HQ-NaFe prepared in step (2), the PFSA-Na solid composite electrolyte membrane prepared in example 1, and sodium metal were transferred to a glove box filled with argon gas to assemble a solid sodium ion battery (coin cell), the model of the coin cell used was CR2032, after the assembly was completed, the battery was removed from the glove box, and then electrochemical testing was performed on a Land test systemThe performance test has the test voltage range of 2-4.2V, and the test result is shown in fig. 9, wherein a in fig. 9 is a charge-discharge curve diagram of the battery in the cycle process, b in fig. 9 is a cycle performance diagram of the battery, and as can be seen from a in fig. 9, when the HQ-NaFe and the PFSA-Na solid-state composite electrolyte membrane are assembled into a solid-state sodium ion battery, a significant charge-discharge platform is provided, which is consistent with the electrochemical behavior of the material in a common electrolyte. As can be seen from a in FIG. 9, the charge-discharge specific capacity of the first ring of the battery reaches 51 mAh g and 122mAh g^-1The performance is excellent, the contact ratio of the charging and discharging curves of 50 circles, 100 circles and 200 circles is high, the polarization is small, and the reversibility of the battery in the circulating process is good. As can be seen from b in fig. 9, the battery has good cycle stability in the actual cycle process, the cycle life is as long as 200 cycles, the reversible capacity attenuation in the cycle process is reduced, and the coulombic efficiency in the cycle process is always close to 100%, which indicates that the electrochemical reaction involved in the cycle process has high reversibility, and further verifies that the PFSA-Na solid composite electrolyte membrane prepared in example 1 and the HQ-NaFe material have good matching performance in energy storage applications.

The 4 kinds of positive electrode materials can be assembled with the PFSA-Na solid composite electrolyte diaphragm to form a solid sodium ion battery (button battery), and the solid sodium ion battery has excellent performance, simple preparation method and easily obtained raw materials, thereby proving that the invention has huge commercial prospect.

Example 7

Sodium ion battery assembled based on PFSA-Na solid composite electrolyte diaphragm and capable of testing operation capacity at low temperature

The positive plate containing HQ-NaFe prepared in step (2) of example 3, the PFSA-Na solid composite electrolyte membrane prepared in example 1, and sodium metal were transferred to a glove box filled with argon gas to assemble a solid sodium ion battery (coin cell), the model of the coin cell used was CR2032, after the assembly, the battery was removed from the glove box, and then an electrochemical performance test was performed on a Land test system at a test voltage range of 2-4.2V, during the test, the battery and the battery holder were placed in a high-low temperature box for temperature control. In the low-temperature experiment process, the adopted low temperatures are respectively 5 ℃, 5 ℃ below zero, and 15 ℃ below zero, before different low-temperature tests are started, the battery is kept still at the temperature for 1h to achieve temperature balance, the number of cycles of each low-temperature test is 60, the low-temperature cycle charge-discharge capacity and the coulombic efficiency are shown in figure 10, as can be seen from figure 10, the battery still keeps stable in low-temperature cycle, the capacity attenuation is reduced, and the coulombic efficiency still keeps 100%, so that the sodium ion battery assembled on the basis of the PFSA-Na solid composite electrolyte membrane still has practical application capability at low temperature.

Finally, the above embodiments are only intended to illustrate the technical solutions of the present invention and not to limit the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions, and all of them should be covered by the claims of the present invention.

Claims

1. A preparation method of a PFSA-Na solid composite electrolyte membrane is characterized by comprising the following steps:

adding PFSA-Li powder and a sodium source into water, uniformly mixing, stirring for 5-24h at 40-150 ℃, then centrifugally washing and drying to obtain PFSA-Na powder, dissolving the PFSA-Na powder in an organic solvent to obtain PFSA-Na glue solution, adding an electrolyte into the PFSA-Na glue solution under stirring to obtain a mixed solution, finally blade-coating the mixed solution, and drying at 60-150 ℃ for 12-48h to obtain the PFSA-Na solid composite electrolyte membrane; the mass fraction of PFSA-Na powder in the PFSA-Na glue solution is 20-40%; the volume ratio of the PFSA-Na glue solution to the electrolyte is 0.5-200: 1.

2. The method of claim 1, wherein the mass ratio of PFSA-Li powder to the sodium source is 1-100: 1-400.

3. The method of claim 1, wherein the electrolyte has a concentration of 1 mol/L.

4. A method according to any one of claims 1 to 3, wherein the sodium source is one of sodium chloride, sodium acetate, sodium nitrate, sodium hydroxide or sodium carbonate.

5. The method as claimed in any one of claims 1 to 3, wherein the centrifugal washing is performed 3-10 times at a speed of 5000-9000r/min with deionized water, each time for 3-5 min.

6. The method according to any one of claims 1 to 3, wherein the drying is in particular drying at 30 to 150 ℃ for 5 to 96 h.

7. The method of any one of claims 1-3, wherein the organic solvent is one of N-dimethylformamide, N-methylpyrrolidinone, acetonitrile, tetrahydrofuran or dimethylsulfoxide.

8. A method according to any one of claims 1 to 3, wherein the solute in the electrolyte is one of sodium perchlorate, sodium hexafluorophosphate, sodium triflate or sodium bistrifluoromethylsulphonimide and the solvent in the electrolyte is one of EC/DEC, EC/PC, DGM or DME.

9. A PFSA-Na solid state composite electrolyte membrane prepared by the method of any one of claims 1 to 8.

10. Use of the PFSA-Na solid state composite electrolyte membrane of claim 9 in a secondary solid state sodium ion battery.