CN104157842B - Perfluor sulfonyl carboxylic acid lighium polymer electrolyte preparation method and lithium-sulfur rechargeable battery - Google Patents

Abstract

The invention discloses a method for preparing a perfluorosulfonyl carboxylate lithium polymer electrolyte. Firstly, methylcarbamoyl chloride and perfluorosulfonyl fluoride resin are stirred and refluxed in an inert atmosphere at a certain temperature in the presence of a solvent. , preparing a perfluorosulfonylformyl chloride resin polymer containing a sulfonylchloride group in the side chain; then hydrolyzing the perfluorosulfonylchloride resin polymer to obtain a polymer containing a sulfonylcarboxylic acid group in the side chain; Then carry out lithium ion exchange reaction to obtain polymer precipitate; after the polymer precipitate is suction filtered, washed, dissolved and concentrated, a perfluorosulfonyl carboxylate lithium polymer electrolyte solution is obtained. The lithium-sulfur secondary battery of the present invention can be prepared by assembling the prepared lithium perfluorosulfonylcarboxylate polymer electrolyte membrane with a lithium negative electrode, a positive electrode sheet, an organic electrolyte, and the like. The polymer electrolyte of the invention can block the penetration of anions and organic molecules, has high ion conductivity and electrochemical stability, and the cycle life of assembled battery products is longer.

Description

Preparation method of perfluorosulfonyl carboxylate lithium polymer electrolyte and lithium-sulfur secondary battery

technical field

The invention relates to the preparation of a functional electrolyte membrane and a corresponding lithium-sulfur battery, in particular to a preparation method of a perfluorosulfonyl carboxylate lithium polymer electrolyte and a lithium-sulfur secondary battery.

Background technique

The current rapid development of communications, portable electronic equipment, electric vehicles and space technology has put forward higher and higher requirements for the performance of energy storage batteries. It is of great significance to develop new lithium batteries with high specific energy, low cost and environmental friendliness. . Li-S secondary batteries based on Li metal anode and sulfur cathode represent one of the highest energy density combinations of known chemically reversible systems. The theoretical energy density of the lithium-sulfur system is 2600Wh/kg, and the actual energy density that can be expected to be achieved is 700Wh/kg, which is three times that of the existing lithium-ion batteries. Although the achievable energy density of lithium-sulfur batteries has reached 300-400Wh/kg, the sulfur positive electrode is not conductive, the electrochemical reaction process is complicated, and the lithium negative electrode has high activity. The intermediate product lithium polysulfide dissolves in the electrolyte during the charging and discharging process of lithium-sulfur batteries. , in the liquid phase diffuses to the negative electrode through the porous diaphragm (that is, the "shuttle effect"), resulting in the consumption of positive active materials and the corrosion and passivation of the negative electrode, which seriously affects the cycle performance of lithium-sulfur batteries.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art, to provide a lithium perfluorosulfonyl carboxylate polymer that can block the penetration of anions and organic molecules, and has high ion conductivity and chemical and electrochemical stability. The preparation method of the solid electrolyte also provides a lithium-sulfur secondary battery with high gram capacity of active material, less dissolution and loss of active material and long cycle life during charging and discharging.

In order to solve the above-mentioned technical problems, the technical solution proposed by the present invention is a preparation method of lithium perfluorosulfonylcarboxylate polymer electrolyte, comprising the following steps:

(1) Carbamoyl chloride and perfluorosulfonyl fluoride resin with ether terminal side groups are reacted under stirring and reflux under an inert atmosphere and a certain temperature in the presence of a solvent. The molar ratio of the sulfonyl fluoride resin is controlled at 5:1 to 1:1, and a perfluorosulfonyl chloride resin polymer containing a sulfonyl chloride group in the side chain is prepared;

(2) Hydrolyze the perfluorosulfonylformyl chloride resin polymer prepared in the above step (1), make it stir and reflux under an inert atmosphere and a certain temperature, and prepare a polymer containing sulfonylcarboxylic acid groups in the side chain thing;

(3) carry out lithium ion exchange reaction with the polymer that the side chain that above-mentioned step (2) makes contains sulfonyl carboxylic acid group, obtain polymer precipitation after sufficient reaction is complete;

(4) Suction filtration, washing, dissolution and concentration of the polymer precipitate to obtain a lithium perfluorosulfonylcarboxylate polymer electrolyte solution.

The above-mentioned preparation method of the present invention is mainly synthesized by a three-step method, that is: first, carbamoyl chloride and perfluorosulfonyl fluoride resin with ether terminal side groups undergo a similar conversion reaction to obtain a side chain containing sulfonylformyl chloride group perfluorosulfonylformyl chloride resin polymer, and then hydrolyzed to obtain a polymer containing sulfonyl carboxylic acid groups in the side chain, and finally obtained a perfluorosulfonyl carboxylate containing lithium sulfonyl carboxylate groups in the side chain through lithium ion exchange reaction lithium polymer.

In the above-mentioned preparation method of the present invention, preferably, in the step (1), the solvent includes tetrahydrofuran, anisole, dioxolane, N-N-dimethylformamide, N-N-dimethylacetamide, N- At least one of methylpyrrolidone, N-ethylpyrrolidone, dichloromethane, dichloroethane, toluene (preferably a mixture of one or two); the temperature of the stirring and reflux reaction is controlled at 40° C. to 120° C. °C, the time for the stirring and reflux reaction is 4h to 30h.

In the above-mentioned preparation method of the present invention, preferably, in the step (2), the temperature of the stirring and reflux reaction is controlled at 40°C to 120°C, and the time of the stirring and reflux reaction is 4h to 30h.

In the above-mentioned preparation method of the present invention, preferably, in the step (3), the process of the lithium ion exchange reaction is specifically soaking the polymer containing sulfonyl carboxylic acid groups in the side chain in 1mol/L～10mol/L In a solution containing lithium salt and/or lithium hydroxide, and at a temperature of 40°C to 100°C, stir and reflux for 0.5h to 10h, or use a titration method to determine whether the lithium ion exchange is complete to control the time for stirring and reflux.

In the above preparation method of the present invention, preferably, the lithium salt in the solution includes lithium chloride (LiCl), lithium perchlorate (LiClO ₄ ), lithium nitrate (LiNO ₃ ), lithium carbonate (Li ₂ CO ₃ ), Lithium sulfate (Li ₂ SO ₄ ), at least one of organic lithium salts (such as lithium acetate, lithium oxalate, etc.), the solvent in the solution preferably includes at least one of water, methanol, ethanol or dimethyl sulfoxide species (other protonated solvents can also be selected).

In the above-mentioned preparation method of the present invention, preferably, in the step (4), the detergent used for suction filtration and washing is a mixed solvent of ethanol and water, and the organic solvent selected for dissolving includes N-N-dimethylformamide, At least one of N-N dimethylacetamide, N-methylpyrrolidone, N-ethylpyrrolidone, dichloroethane, dimethylsulfoxide or sulfolane (preferably a mixture of one or two);

The specific operation of dissolving includes: firstly make the content of the polymer reach 4%-50%, stirring and dissolving at a temperature of 30°C-100°C;

The specific operation of the concentration includes: filtering out insoluble matter in the dissolved solution system with a sieve, and concentrating the solution system to a concentration of 7wt.%-30wt.%.

In the above-mentioned preparation method of the present invention, preferably, the same solvent system is used in the reaction process of the step (1) to step (3), and the use of the same solvent system can avoid the cumbersome operation of solvent removal treatment, and reduce the The loss of products during the treatment process and the possible side reactions caused by high-temperature distillation and concentration. More preferably, the solvent system is a mixed solvent system comprising one or two ethers and other types of solvents, because the mixed solvent system comprising one or two ethers can adapt to the above steps (1) and In the reaction process of (2), in order to increase the reaction temperature and reduce the requirements of solvent volatilization, it is easy to realize the purification of each main product of the two-step reaction.

The above-mentioned preparation method of the present invention, preferably, also includes step (5) after the step (4), and the specific operation of the step (5) includes: making the obtained perfluorosulfonyl carboxylate lithium polymer electrolyte The solution is coated with a coater, scraped with a knife coater or cast to form a film. After initial drying, an extractant can be optionally added for secondary film formation. After vacuum drying, heat treatment at 120°C to 200°C for 0.5h to 4h, After cooling, the perfluorosulfonyl carboxylate lithium polymer electrolyte membrane is obtained; the selected extractant is ethanol, isopropanol, ether, propyl ether, tetrahydrofuran, ethylene carbonate, propylene carbonate, diethyl carbonate, methyl carbonate At least one of ethyl ester, dioxolane, water, dichloromethane, dichloroethane, and toluene. The addition of the extractant is beneficial to the complete removal of the volatile matter of the electrolyte membrane, and it is also beneficial to the demoulding of the electrolyte.

As a general technical concept, the present invention also provides a lithium-sulfur secondary battery, comprising a lithium negative electrode, a positive electrode sheet, an electrolyte membrane, and an organic electrolyte;

The electrolyte membrane is the lithium perfluorosulfonylcarboxylate polymer electrolyte membrane obtained by the above-mentioned preparation method of the present invention;

The lithium negative electrode mainly includes negative electrode active materials composed of lithium metal or lithium-containing alloys; and may also include conductive materials and binders;

The positive electrode sheet is mainly composed of a current collector that conducts current and a positive active material coated on the current collector, a conductive agent and a binder; the positive active material is sulfur element, organic sulfide, carbon sulfur polymer at least one of

The organic electrolytic solution comprises a lithium salt and a non-aqueous solvent, and the lithium salt is selected from lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium hexafluoroarsenate (LiAsF ₆ ), lithium perchlorate (LiClO ₄ ), lithium trifluoromethanesulfonyl imide (LiN(CF ₃ SO ₂ ) ₂ ), lithium trifluoromethanesulfonate (LiSO ₃ CF ₃ ), lithium nitrate, lithium polysulfide of different valence states at least A kind; Described non-aqueous solvent comprises acetonitrile, cyclohexane, cyclohexanone, isopropanol, tetrahydrofuran, 2-methyltetrahydrofuran, ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, Diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, ethyl butyrate, Dimethoxyethane, 1,3-dioxolane, diglyme (dimethoxyethyl ether), triglyme, tetraglyme, diethylene glycol At least one of dimethyl ether, sulfolane, dimethyl sulfoxide, and dimethyl sulfone. By adjusting the type and concentration of the non-aqueous solvent in the organic electrolyte, the ion conduction characteristics of the electrolyte membrane can be adjusted within a certain range, affecting the conductivity of the electrolyte membrane, and improving the cycle performance of the lithium-sulfur battery. The non-aqueous solvent preferably added above has a certain activation effect on the electrolyte membrane. After the electrolyte membrane absorbs the organic solvent in the electrolyte and reaches a certain balance, it can conduct lithium ions well in the lithium-sulfur battery with higher ion conductivity and Inhibit the mutual migration and diffusion of anions and organic molecules between positive and negative electrodes.

In the above-mentioned lithium-sulfur secondary battery, preferably, the current collector is aluminum foil or aluminum mesh, and the conductive agent is a carbon-based conductive agent, such as one or more of preferred conductive carbon black, acetylene black or graphite powder kind, the binder is polyethylene oxide, styrene-butadiene rubber, polyvinylidene fluoride or polyvinylidene fluoride-hexafluoropropylene copolymer; wherein, the mass fractions of positive electrode active material, conductive agent and binder are respectively 50% to 80%, 15% to 30% and 5% to 20%.

Compared with the prior art, the present invention has the advantages of:

1. The lithium perfluorosulfonylcarboxylate polymer electrolyte membrane prepared by the above-mentioned preparation method of the present invention has a highly crystalline main chain to form a dense barrier layer, and the side chain has anion fixed charges, which jointly block the penetration of anions and organic molecules, thereby obtaining A single cation migrates. The main chain of the polymer electrolyte is a perfluorinated carbon-carbon chain, and the anion fixed in the side chain is a sulfonyl carboxylic acid anion with a large volume, and has high ion conductivity and chemical and electrochemical stability.

2. The preparation method of the present invention adopts perfluorosulfonyl fluoride resin as a raw material, and prepares it through a similar conversion reaction with methylcarbamoyl chloride, the process steps are simple, and the yield is higher than 90%.

3. The lithium-sulfur secondary battery of the present invention mainly suppresses the interdiffusion of polysulfide anions, alkoxide anions and organic solvents between the positive and negative electrodes through the functional polymer electrolyte membrane prepared by the present invention. It is shown to prevent the diffusion of polysulfide anion and alkoxy anion in the electrolyte and the side reaction with the lithium metal anode, and has a high ionic conductivity, so as to ensure that the active material exerts a high gram capacity during the charging and discharging process of the battery, and at the same time The dissolution and loss of the active material is reduced, and the cycle performance and cycle life of the lithium-sulfur secondary battery are improved (the capacity of the lithium-sulfur secondary battery maintains more than 80% after 500 cycles).

Description of drawings

Fig. 1 is a curve diagram of the energy capacity retention rate of the charge and discharge cycles of the product prepared in Example 1 of the present invention.

Fig. 2 is a curve diagram of the energy capacity retention rate of the charge and discharge cycles of the product prepared in Example 2 of the present invention.

detailed description

In order to facilitate the understanding of the present invention, the present invention will be described more fully and in detail below in conjunction with the accompanying drawings and preferred embodiments, but the protection scope of the present invention is not limited to the following specific embodiments.

Unless otherwise defined, all technical terms used hereinafter have the same meanings as commonly understood by those skilled in the art. The terminology used herein is only for the purpose of describing specific embodiments, and is not intended to limit the protection scope of the present invention.

Unless otherwise specified, the various reagents and raw materials used in the present invention are commercially available products or products that can be prepared by known methods.

Example 1:

A preparation method of perfluorosulfonyl carboxylate lithium polymer electrolyte of the present invention, comprises the following steps:

(1) Dissolve 0.6g of carbamoyl chloride in 200g of anisole, then add 25g of perfluorosulfonyl fluoride resin to the solution, stir and reflux at 70°C for 15h under a nitrogen atmosphere, remove unreacted raw materials and By-products are precipitated to obtain perfluorosulfonylformyl chloride resin polymers containing sulfonylformyl chloride groups in their side chains. The perfluorosulfonylformyl chloride resin polymer was filtered and washed with a mixed solvent such as ethanol and water, and then dried to obtain 26.8 g of a solid product. The ion exchange capacity of the perfluorosulfonyl fluoride resin used is 0.9 mmol/100 g.

(2) Add 26.8 g of the solid product obtained in the above step (1) into 80 g of deionized water, stir and reflux at 70°C for 4 hours under the protection of nitrogen, and prepare a polymer containing sulfonyl carboxylic acid groups in the side chain after suction filtration. thing.

(3) the polymer that the side chain that above-mentioned step (2) makes contains sulfonyl carboxylic acid group is joined in the LiOH/ethanol/water mixed solvent of 4mol/L, and ethanol and water mass ratio are 1/3, in Stirred and refluxed at 70°C for 8 hours to obtain a polymer precipitate.

(4) The polymer precipitate obtained in the above step (3) is suction filtered, washed and dissolved. When dissolving, the polymer precipitate is first dissolved in N-methylpyrrolidone so that its solid content in the solution system reaches 4%. ~50%, then stirred and dissolved at 90°C, filtered out the insoluble matter in the dissolved solution system with a 60-mesh screen, and concentrated the solution system to a concentration of 10%, to obtain a lithium perfluorosulfonyl carboxylate electrolyte solution.

(5) The perfluorosulfonyl carboxylate lithium polymer electrolyte solution prepared in the above step (4) is scraped and coated with a scraper to form a film, and after initial drying, add the mixed solution of extractant ethanol and water mass ratio of 1/2 Soaking, replacing the N-methylpyrrolidone in the original solution system for secondary film formation, vacuum drying after demoulding, heat treatment at 140°C for 0.5h, and cooling to obtain lithium perfluorosulfonylcarboxylate polymer electrolyte membrane.

A lithium-sulfur (Li-S) secondary battery of the present invention and a preparation process thereof, comprising a lithium negative electrode, a positive electrode sheet, an electrolyte membrane, and an organic electrolyte;

The electrolyte membrane is the lithium perfluorosulfonylcarboxylate polymer electrolyte membrane obtained by the preparation method of the above-mentioned embodiment;

The lithium negative electrode mainly includes a negative electrode active material composed of lithium foil; and may also include conductive materials and binders;

The positive electrode sheet is mainly composed of a current collector (such as aluminum foil or aluminum mesh) and a positive active material coated on the current collector, a conductive agent and a binder; the positive active material is a carbon-sulfur polymer. The conductive agent is carbon-based Conductive agent, such as conductive carbon black, acetylene black or graphite powder; Binding agent is polyvinylidene fluoride; Wherein, the mass percent of positive electrode active material, conducting agent and binding agent are respectively 70%, 19% and 11%; Will The positive electrode active material, conductive agent, binder (and some other additives) were weighed according to the aforementioned ratio and mixed by ball milling for 4 hours, and a double-sided coated positive electrode sheet was prepared using a coating machine. The positive electrode active material loading was 6mg/ cm ² , cut into 10cm long and 5cm wide positive electrode pieces, and vacuum dry at 60°C for 12h;

Then, the positive electrode sheet, the above-mentioned lithium perfluorosulfonylcarboxylate polymer electrolyte membrane, and lithium foil are wound in a glove box to prepare a battery cell. The thickness of the lithium foil used is 100 μm, and then 1M lithium hexafluorophosphate/ethylene glycol di Diethyl ether (DME)/1,3-dioxolane (DOL) electrolyte, packaged and placed for 24 hours, and its electrical properties were tested. At room temperature, the voltage is limited to 2.5V ~ 1.5V, and the current is 0.75mA/cm ³ . After testing, the Li-S secondary battery C/10 prepared in this example was charged and discharged, and the capacity was maintained at 70% after 100 charge and discharge cycles (see FIG. 1 ).

Example 2:

A preparation method of perfluorosulfonyl carboxylate lithium polymer electrolyte of the present invention, comprises the following steps:

(1) Dissolve 4.88g of carbamoyl chloride in 10g of tetrahydrofuran, then add 20g of perfluorosulfonyl fluoride resin to the solution, stir and reflux at 70°C for 15h under a nitrogen atmosphere, and remove unreacted raw materials and precipitates by suction filtration By-products, perfluorosulfonylformyl chloride resin polymers containing sulfonylformyl chloride groups in the side chains are obtained. The perfluorosulfonylformyl chloride resin polymer was filtered and washed with a mixed solvent such as ethanol and water, and then dried to obtain 21.6 g of a solid product.

(2) Add 21.6 g of the solid product obtained in the above step (1) into 80 g of deionized water, stir and reflux at 70°C for 4 hours under the protection of nitrogen, and prepare a polymer containing sulfonyl carboxylic acid groups in the side chain after suction filtration. thing.

(3) Add the polymer containing sulfonyl carboxylic acid groups in the side chain prepared in the above step (2) into 4mol/L lithium acetate/ethanol solution, stir and reflux at 70°C for 8h to obtain a polymer precipitate .

(4) Suction filter, wash and dissolve the polymer precipitate obtained in the above step (3). When dissolving, first dissolve the polymer precipitate in N,N-dimethylformamide to make it solid in the solution system The content reaches 4% to 50%, and then stirred and dissolved at 90°C, filtered out the insoluble matter in the dissolved solution system with a 60-mesh screen, and concentrated the solution system to a concentration of 7wt.%, to obtain perfluorosulfonyl carboxyl Lithium oxide solution.

(5) Scrape the lithium perfluorosulfonylcarboxylate polymer electrolyte solution prepared in the above step (4) with a scraper to coat the film. After the film is formed, it is released from the mold and dried in vacuum. It is heat-treated at 140°C for 0.5h, and it is ready to use after cooling. The perfluorosulfonyl carboxylate lithium polymer electrolyte membrane was obtained.

A lithium-sulfur (Li-S) secondary battery of the present invention and a preparation process thereof, comprising a lithium negative electrode, a positive electrode sheet, an electrolyte membrane, and an organic electrolyte;

The electrolyte membrane is the lithium perfluorosulfonylcarboxylate polymer electrolyte membrane obtained by the preparation method of the above-mentioned embodiment;

The lithium negative electrode mainly includes a negative electrode active material composed of lithium foil; and may also include conductive materials and binders;

The positive electrode sheet is mainly composed of a current collector (such as aluminum foil or aluminum mesh) and a positive active material coated on the current collector, a conductive agent and a binder; the positive active material is a carbon-sulfur polymer. The conductive agent is carbon-based Conductive agent, such as conductive carbon black, acetylene black or graphite powder; Binding agent is polyvinylidene fluoride; Wherein, the mass percent of positive electrode active material, conducting agent and binding agent are respectively 70%, 19% and 11%; Will The positive electrode active material, conductive agent, binder (and some other additives) etc. were weighed according to the aforementioned ratio and mixed by ball milling for 3 hours, and a double-sided coated positive electrode sheet was prepared by using a coating machine. The positive electrode active material loading was 6mg/ cm ² , cut into 10cm long and 5cm wide positive electrode pieces, and vacuum dry at 60°C for 12h;

Then, the positive pole piece, the above-mentioned lithium perfluorosulfonylcarboxylate polymer electrolyte membrane, and lithium foil are wound in a glove box to prepare a battery cell. The thickness of the lithium foil used is 100 μm, and then 1M trifluoromethylsulfonyl Lithium imide/triglyme, packaged and left for 24 hours, tested its electrical properties. At room temperature, the voltage is limited to 2.5V ~ 1.5V, and the current is 0.75mA/cm ² . After testing, the Li-S secondary battery C/10 prepared in this example was charged and discharged, and the capacity was maintained at 65% after 100 charge and discharge cycles (see FIG. 2 ).

Claims (10)

1. a perfluor sulfonyl carboxylic acid lighium polymer electrolyte preparation method, comprises the following steps:

(1) by the perfluor sulfonyl fluoro-resin of methylcarbamyl chloride and band aether terminal group lateral group in the presence of solvent and stirring and refluxing reaction under inert atmosphere and certain temperature, the mol ratio of described methylcarbamyl chloride and perfluor sulfonyl fluoro-resin controls 5: 1��1: 1, prepares the perfluor sulfonyl formyl chloride resinous polymer of side chain containing sulphonyl formyl chloride group;

(2) the perfluor sulfonyl formyl chloride resinous polymer that above-mentioned steps (1) is obtained is hydrolyzed so that it is stirring and refluxing reaction under inert atmosphere and certain temperature, prepares the polymkeric substance of side chain containing sulphonyl hydroxy-acid group;

(3) polymkeric substance that side chain obtained for above-mentioned steps (2) contains sulphonyl hydroxy-acid group carries out lithium ion exchanged reaction, obtains polymer precipitation after fully reacting completely;

(4) described polymer precipitation is carried out filtering and washing, dissolving, concentrated after, obtain perfluor sulfonyl carboxylic acid lighium polymer electrolyte solution.

2. preparation method according to claim 1, it is characterized in that: in described step (1), described solvent comprises at least one in tetrahydrofuran (THF), methyl-phenoxide, dioxolane, N-N-dimethyl formamide, N-N N,N-DIMETHYLACETAMIDE, N-Methyl pyrrolidone, N-ethyl pyrrolidone, methylene dichloride, ethylene dichloride, toluene; The temperature of described stirring and refluxing reaction controls at 40 DEG C��120 DEG C, and the time of described stirring and refluxing reaction is 4h��30h.

3. preparation method according to claim 1, it is characterised in that: in described step (2), the temperature of described stirring and refluxing reaction controls at 40 DEG C��120 DEG C, and the time of described stirring and refluxing reaction is 4h��30h.

4. preparation method according to claim 1, it is characterized in that: in described step (3), the polymkeric substance that side chain is specifically contained sulphonyl hydroxy-acid group by the process of described lithium ion exchanged reaction is immersed in the solution that 1mol/L��10mol/L contains lithium salt and/or lithium hydroxide, and at 40 DEG C��100 DEG C temperature, stirring and refluxing reaction 0.5h��10h.

5. preparation method according to claim 4, it is characterized in that: in described step (3), described lithium salt comprises at least one in lithium chloride, lithium perchlorate, lithium nitrate, Quilonum Retard, Lithium Sulphate, organic lithium salt, and the solvent in described solution comprises at least one in water, methyl alcohol, ethanol or dimethyl sulfoxide (DMSO).

6. preparation method according to claim 1, it is characterized in that: in described step (4), the washing composition carrying out filtering and washing employing is the mixed solvent of ethanol, water, and the organic solvent that described dissolving is selected comprises at least one in N-N-dimethyl formamide, N-N N,N-DIMETHYLACETAMIDE, N-Methyl pyrrolidone, N-ethyl pyrrolidone, ethylene dichloride, dimethyl sulfoxide (DMSO) or tetramethylene sulfone;

The concrete operation of described dissolving comprises: the content first making polymer precipitation in solution system reaches 4%��50%, then stirring and dissolving at 30 DEG C��100 DEG C temperature;

Described concentrated concrete operation comprises: the insolubles in solution system after dissolving with screen cloth filtering, and solution system is concentrated to concentration be 7wt.%��30wt.%.

7. preparation method according to claim 1, it is characterised in that: the reaction process of described step (1)��step (3) all uses identical solvent system, and described solvent system is the solvent system comprising a kind of ether material.

8. preparation method according to any one of claim 1��7, it is characterized in that: after described step (4), also comprise step (5), the concrete operation of described step (5) comprising: is coated with by obtained perfluor sulfonyl carboxylic acid lighium polymer electrolyte solution coating machine, scrapes and be coated with device and scrape and be coated with film forming or casting film-forming, extraction agent two-step film forming is added after just doing, after vacuum-drying, 120 DEG C��200 DEG C thermal treatment 0.5h��4h, namely obtain perfluor sulfonyl carboxylic acid lighium polymer dielectric film after cooling; Selected extraction agent is at least one in ethanol, Virahol, ether, propyl ether, tetrahydrofuran (THF), NSC 11801, propylene carbonate, diethyl carbonate, Methyl ethyl carbonate, dioxolane, water, methylene dichloride, ethylene dichloride, toluene.

9. a lithium-sulfur rechargeable battery, comprises cathode of lithium, anode pole piece, dielectric film, organic electrolyte; It is characterized in that:

Described dielectric film is the perfluor sulfonyl carboxylic acid lighium polymer dielectric film that preparation method described in claim 8 obtains;

Described cathode of lithium mainly comprises lithium metal or the negative active core-shell material of lithium alloys composition;

Described anode pole piece is primarily of the collector of conduction current and coating positive electrode active materials on a current collector, conductive agent and tackiness agent composition; Described positive electrode active materials is at least one in sulphur simple substance, organic sulfide, carbon-sulfur polymer;

Described organic electrolyte comprises lithium salt and non-aqueous solvent, at least one that described lithium salt is selected from the poly-sulphur lithium of lithium hexafluoro phosphate, LiBF4, hexafluoroarsenate lithium, lithium perchlorate, lithium trifluoromethanesulp,onylimide, trifluoromethyl sulfonic acid lithium, lithium nitrate, different valence state, described non-aqueous solvent comprises acetonitrile, hexanaphthene, pimelinketone, Virahol, tetrahydrofuran (THF), 2-methyltetrahydrofuran, NSC 11801, propylene carbonate, butylene, methylcarbonate, diethyl carbonate, Methyl ethyl carbonate, methyl propyl carbonate, methyl-formiate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, ethyl butyrate, glycol dimethyl ether, 1, 3-dioxolane, diglyme, triglyme, tetraethylene glycol dimethyl ether, glycol dimethyl ether, tetramethylene sulfone, two sub-MSMs, at least one in dimethyl sulfone.

10. lithium-sulfur rechargeable battery according to claim 9, it is characterized in that: described collector is aluminium foil or aluminium net, described conductive agent is one or more in conductive carbon black, acetylene black or Graphite Powder 99, and described tackiness agent is polyoxygenated ethane, styrene-butadiene rubber(SBR), polyvinylidene difluoride (PVDF) or polyvinylidene difluoride (PVDF)-hexafluoropropylene copolymer; Wherein, the massfraction of positive electrode active materials, conductive agent and tackiness agent is respectively 50%��80%, 15%��30% and 5%��20%.