CN106711503A - Single-ion gel polymer electrolyte and preparation method thereof - Google Patents

Abstract

The invention relates to a single-ion gel polymer electrolyte and a preparation method thereof, which is characterized in that: firstly, using the insoluble characteristic of sodium sulfate in absolute ethanol, the sodium salt of sulfonic acid with a double bond is selected to prepare lithium salt of sulfonic acid with a double bond; and then synthesized Prepare a single-ion polymer matrix, wherein the molar ratio of the carbon-carbon double bond in the added monomer to lithium sulfonate is in the range of 10:1-1:10, the catalyst is 2wt.% azobisisobutyronitrile, and the solvent is toluene , react at 70-80°C for 7-12h; then, use the prepared polymer as a matrix to prepare a single-ion gel polymer electrolyte, wherein the addition amount of polymer, organic solvent and liquid electrolyte is 1-3g and 20 -50ml. The beneficial effect of the present invention is that the introduction of lithium ions into the polymer in the form of chemical bonds increases the lithium ion transfer number of the electrolyte, which not only provides the possibility to further improve the energy density of lithium ion batteries, but also provides a new solution for gel polymer electrolytes. The application in actual production lays a certain foundation.

Description

Single ion gel polymer electrolyte and preparation method thereof

technical field

The invention relates to a single-ion gel polymer electrolyte and a preparation method thereof, belonging to the technical field of lithium ion batteries.

Background technique

At present, lithium-ion batteries have made great progress and have been widely used in digital products, electric tools, vehicles, lighting and other fields. However, lithium-ion batteries still have the disadvantage of low endurance due to low energy density. The lithium ion migration number of the electrolyte used in lithium-ion batteries is one of the key factors determining the energy of the battery. In order to increase the lithium ion migration number in the electrolyte, the most commonly used method is to increase the volume of the anion of the lithium salt added to the electrolyte, such as introducing an organic large anion group lithium salt. This method has indeed achieved some effects to a certain extent. However, these lithium salts with large organic groups have brought the problem of poor electrochemical performance stability. In addition, the gel polymer electrolyte is composed of three parts: polymer matrix, plasticizer and lithium salt. It is a kind of electrolyte with high ion conductivity, high safety and good electrochemical performance. One of the important supports for great development. Based on the advantages of the gel polymer electrolyte, the present invention aims at increasing the migration number of lithium ions in the electrolyte, and proposes to introduce lithium ions into the polymer matrix in the gel polymer electrolyte in the form of chemical bonds. This method makes the polymer matrix The polymer chain becomes an anionic group. When the electrolyte conducts ions, the anionic groups of the polymer chain obviously do not migrate, so the migration number of lithium ions must be greatly improved. Related studies have not yet appeared in domestic and foreign reports.

Contents of the invention

technical problem to be solved

In order to increase the lithium ion migration number of the gel polymer electrolyte, the invention proposes a single-ion gel polymer electrolyte and a preparation method thereof.

Technical solutions

The single-ion gel polymer electrolyte and its preparation method are characterized in that: the specific steps are as follows:

(1) Preparation of lithium sulfonate salt with double bond: Weigh water-soluble sodium sulfonate salt with carbon-carbon double bond and pour it into a beaker, add deionized water, stir fully, and prepare sodium sulfonate saturated solution; configure A sulfuric acid solution with a concentration in the range of 1-5mol/L; add the sulfuric acid solution to the saturated sodium sulfonate solution, stir evenly, and ensure that the molar ratio of sodium ions to sulfate ions is 2:1; then, the obtained uniform Transfer the solution into the separatory funnel, drain the absolute ethanol solvent with a glass rod from the top of the funnel, and use the characteristic that sodium sulfate is insoluble in ethanol, and sodium sulfate will precipitate at the interface between water and ethanol; release the aqueous solution below the funnel into the beaker Then transfer to a separatory funnel and precipitate with absolute ethanol. Repeat the above operations to completely remove the sodium ions to obtain a sulfonic acid aqueous solution; add anhydrous lithium hydroxide to the sulfonic acid aqueous solution, stir until pH = 7, and remove the water solvent by rotary evaporation to obtain lithium sulfonic acid salt powder with double bonds.

(2) Preparation of single-ion polymer matrix: mix one or more of acrylates, acrylonitriles, vinylidene fluorides, phosphazenes and vinyl acetate monomers, and add them to the pre-dissolved In the toluene solvent of double-bond lithium sulfonate salt, the molar ratio of the carbon-carbon double bond in the monomer to the carbon-carbon double bond in the double-bond lithium sulfonate salt is within the range of 10:1-1:10, and then add the total reactant The mass of 2wt.% of the catalyst azobisisobutyronitrile is passed through nitrogen, and the reaction is stirred in a three-necked flask at 70-80° C. for 7-12 hours. The resulting material was poured into a beaker filled with deionized water, resulting in a pale yellow latex-like polymer precipitate. Dissolving with toluene and precipitating with deionized water were repeated three times to obtain a white latex solid. The obtained solid was dried and pulverized, washed three times with deionized water, and dried in vacuum for two days to obtain a white powder.

(3) Preparation of single-ion gel polymer electrolyte: Weigh 1-3g of the polymer prepared in the above step (2) and put it in a beaker, add 20-50ml of organic solvent, stir until completely dissolved, pour into polytetrafluoroethylene In the plate, after the organic solvent is completely volatilized, a transparent hard film is obtained, and the film is immersed in the liquid electrolyte for a long enough time to obtain a soft gel polymer electrolyte film.

The single-ion gel polymer electrolyte and its preparation method are characterized in that: the sodium sulfonate salt is sodium p-styrenesulfonate, sodium vinylsulfonate, sodium propenesulfonate, methylpropenesulfonic acid Sodium, sodium 2-acrylamido-2-methylpropanesulfonate or a combination of several.

The single-ion gel polymer electrolyte and its preparation method are characterized in that: the organic solvent is one or more of acetone, tetrahydrofuran, N, N dimethylformamide, dimethyl sulfoxide, etc. Solution mixing.

The single-ion gel polymer electrolyte and its preparation method are characterized in that: the plasticizer in the liquid electrolyte is propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate One or a mixture of esters, etc.; the lithium salt in the liquid electrolyte is one or a mixture of lithium perchlorate, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium trifluoromethanesulfonate, etc. .

Beneficial effect

The beneficial effect of the present invention is that introducing lithium ions on the polymer matrix in the gel polymer electrolyte increases the lithium ion migration number of the electrolyte, which not only provides the possibility to further improve the energy density of the lithium ion battery, but also provides a The application of polymer electrolytes in actual production lays a certain foundation.

Description of drawings

Figure 1 is the appearance of P(MMA-SSS-Li) single-ion gel polymer electrolyte membrane.

Fig. 2 is the AC impedance spectrum of P(MMA-SSS-Li) single-ion gel polymer electrolyte membrane at 25°C, 30°C, 35°C, 40°C, 45°C and 50°C.

detailed description

The present invention will be further described below in conjunction with accompanying drawing and specific embodiment:

Example

(1) Preparation of lithium sulfonate with double bond: Weigh 0.05mol of water-soluble sodium p-styrene sulfonate (SSS), pour it into a beaker, add 40ml of deionized water, stir fully, and prepare saturated sodium sulfonate solution; configure the sulfuric acid solution 5ml within the concentration 5mol/L scope; join the sulfuric acid solution in the saturated solution of sulfonic acid sodium salt, stir evenly, guarantee that the mol ratio of sodium ion and sulfate ion is 2: 1; Then, will obtain Transfer the uniform solution into the separatory funnel, drain the absolute ethanol solvent from the upper opening of the funnel with a glass rod, and use the characteristic that sodium sulfate is insoluble in ethanol, sodium sulfate precipitates at the interface between water and ethanol; release the aqueous solution below the funnel into beaker, then transferred to a separatory funnel, and precipitated with absolute ethanol. Repeat the above operations to completely remove the sodium ions to obtain an aqueous solution of p-styrenesulfonic acid; add anhydrous lithium hydroxide to the aqueous solution of p-styrenesulfonic acid, stir until pH = 7, and remove the water solvent by rotary evaporation to obtain p-styrene Lithium sulfonate (SSS-Li) powder.

(2) Preparation of single-ion polymer matrix: Measure 6.7ml of methyl methacrylate (MMA), weigh 4.13g of p-styrenesulfonate lithium (SSS-Li), and 0.01g of azobisisobutyronitrile. Put in a beaker, add 150ml of toluene, stir until fully dissolved into a transparent solution; transfer the solution into a three-necked flask, heat to 75°C, blow nitrogen, stir and reflux for 8 hours; pour the obtained substance into a beaker filled with deionized water In, a light yellow latex polymer precipitate was obtained. Dissolving with toluene and precipitating with deionized water were repeated three times to obtain a white latex solid. The obtained solid was dried and pulverized, washed three times with deionized water, and dried in vacuum for two days to obtain poly(methyl methacrylate-lithium p-styrenesulfonate) (P(MMA-SSS-Li)) white powder.

(3) Preparation of single-ion gel polymer electrolyte: Weigh 2 g of the polymer P(MMA-SSS-Li) prepared in the above step (2) and place it in a beaker, add 40 ml of organic solvent, stir until completely dissolved, pour After the organic solvent is completely volatilized, a transparent hard film is obtained, and the film is immersed in the liquid electrolyte for a long enough time to obtain a soft gel polymer electrolyte film.

The P(MMA-SSS-Li) single-ion gel polymer electrolyte membrane prepared in the example was tested and analyzed on an electrochemical workstation CHI-660D of Shanghai Chenhua Company, China. The AC impedance test condition is that the scanning frequency range is 0.1Hz to 100kHz, the exchange signal amplitude is 10mV, and the electrodes are ^two stainless steels with an area of 1cm2; the linear scanning test condition is that the scanning frequency range is 0.1Hz to 100kHz, and the scanning rate is 1mV·s ^-1 , the negative electrode is a lithium sheet, and the positive electrode is stainless steel; the test conditions for the lithium ion migration number are AC impedance frequency range 0.1Hz-100kHz, exchange signal amplitude 10mV, and polarization voltage applied by DC polarization 10mV. The result of the test is that the ionic conductivity of the P(MMA-SSS-Li) single-ion gel polymer electrolyte at 25°C, 30°C, 35°C, 40°C, 45°C and 50°C is 1.22×10 ^-3 S·cm ^-1 , 1.43×10 ^-3 S·cm ^-1 , 1.68×10 ^-3 S·cm ^-1 , 1.96×10 ^-3 S·cm ^-1 , 2.24×10 ^-3 S·cm ^-1 and 2.69×10 ^-3 S·cm ^-1 ; the electrochemical stability window of the gel polymer electrolyte reaches 4.65V; the lithium ion transfer number reaches 6.88.

Claims (4)

1. single ion gel polymer electrolyte and preparation method thereof, it is characterised in that：Comprise the following steps that：

(1) with the preparation of double bond sulfonic acid lithium salts：Weigh the water miscible sulfonate sodium with carbon-carbon double bond to pour into beaker, addition is gone Ionized water, is sufficiently stirred for, and prepares sulfonate sodium saturated solution；Sulfuric acid solution of the configuration concentration in the range of 1-5mol/L；By sulphur Acid solution is added in sulfonate sodium saturated solution, is stirred, it is ensured that the mol ratio of sodium ion and sulfate ion is 2: 1； Then, the homogeneous solution that will be obtained is transferred in separatory funnel, and square opening is utilized with glass bar drainage anhydrous ethanol solvent from funnel The characteristics of sodium sulphate does not dissolve in ethanol, sodium sulphate is precipitated out at water and ethanol intersection interface；By the aqueous solution below funnel It is released into beaker, then is transferred in separatory funnel, is precipitated with absolute ethyl alcohol.Operated more than repeating, sodium ion is removed completely, obtained To the sulfonic acid aqueous solution；Anhydrous lithium hydroxide is added in the sulfonic acid aqueous solution, is stirred, until pH=7, rotary evaporation is gone out water-soluble Agent, obtains band double bond Sulfonic Lithium salt powder.

(2) preparation of single-ion polymer matrix：By esters of acrylic acid, vinyl cyanide, vinylidene class, phosphonitrile class and acetic acid second One or more mixing in alkene esters monomer, are added to and dissolved in advance in the toluene solvant with double bond sulfonic acid lithium salts, addition In monomer in carbon-carbon double bond and double bond sulfonic acid lithium salts carbon-carbon double bond mol ratio 10: within the scope of 1-1: 10, add reactant The catalyst azodiisobutyronitrile of gross mass 2wt.%, lead to nitrogen, at 70-80 DEG C in there-necked flask stirring reaction 7-12h.Will The material for obtaining is poured into the beaker equipped with deionized water, obtains light yellow latex shaped polymer precipitation.Again with toluene dissolves, goes Ionized water is precipitated, and is repeated three times, obtains white latex shape solid.The solid crushed after being dried that will be obtained, deionization Water washing three times, is vacuum dried two days, obtains white powder.

(3) preparation of single ion gel polymer electrolyte：Prepared polymer is placed in beaker in weighing 1-3g above-mentioned steps (2) In, 20-50ml organic solvents are added, stir to being completely dissolved, pour into Teflon dish, treat that organic solvent volatilizees completely Transparent dura mater is obtained afterwards, film is immersed in liquid electrolyte enough for a long time, obtain soft gel polymer electrolyte film.

2. single ion gel polymer electrolyte according to claim 1 and preparation method thereof, it is characterised in that：Described Sulfonate sodium be sodium p styrene sulfonate, sodium vinyl sulfonate, sodium allylsulfonate, methylpropene sodium sulfonate, 2- acrylamidos- The mixing of one or more of 2- methyl propane sulfonic acid sodium.

3. described single ion gel polymer electrolyte according to claim 1 and preparation method thereof, it is characterised in that： Described organic solvent is one or more solution in acetone, tetrahydrofuran, DMF, dimethyl sulfoxide etc. Mixing.

4. described single ion gel polymer electrolyte according to claim 1 and preparation method thereof, it is characterised in that： Plasticizer in the liquid electrolyte is propene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, carbonic acid first The mixing of one or more in ethyl ester etc.；Lithium salts in the liquid electrolyte is lithium perchlorate, lithium hexafluoro phosphate, tetrafluoro boron One or several mixing in sour lithium, trifluoromethyl sulfonic acid lithium etc..