CN110265714A - A kind of ionic polymer electrolyte material and its preparation method and application - Google Patents

Abstract

The invention discloses an ionic polymer electrolyte material, a preparation method and application thereof. The preparation method of the present invention comprises the following steps: 1) sulfonating polyether ether ketone to obtain sulfonated polyether ether ketone; 2) ionizing the sulfonated polyether ether ketone obtained in step 1). An ionic polymer electrolyte material is prepared by the above preparation method. A battery separator, prepared from the ionic polymer electrolyte material prepared by the above-mentioned preparation method. The battery diaphragm prepared by the diaphragm material of the present invention has higher thermal dimensional stability; the diaphragm material has a variety of polar groups, making it better compatible with the polar liquid electrolyte; in addition, this type of material It has ion conductivity, which can effectively improve the ion conductivity; and because the sulfonate negative ions are suspended on the polymer skeleton, this type of polymer electrolyte membrane material exhibits single ion conductivity, and as a battery separator, the ions of the polymer electrolyte will The number of migrations has been greatly improved.

Description

A kind of ionic polymer electrolyte material and its preparation method and application

technical field

The invention relates to the technical field of energy storage equipment, in particular to an ionic polymer electrolyte material and its preparation method and application.

Background technique

Although the research and development of advanced energy storage devices is the research focus of important researchers in the field of materials science worldwide. Modern electrochemistry in the last two decades. Lithium-ion batteries power the vast majority of portable devices and have overcome the barriers to large-scale use in many high-energy-density devices.

With the development of diaphragm and electrode preparation technology, the shape of lithium-ion batteries can become thinner and thinner (the thinnest can reach 0.5mm), which also makes it possible to prepare batteries of various shapes, sizes and capacities. At the same time, the energy of polymer lithium-ion batteries far exceeds that of ordinary lithium-ion batteries. Compared with traditional lithium-ion batteries, their capacity, charge and discharge characteristics, safety, and cycle life have also been greatly improved. The separators widely used in the market today are mainly polyolefin-based separators based on polyethylene (PE) and polypropylene (PP). This type of diaphragm is cheap, the preparation process is simple and quick, and when used as a battery diaphragm, the cycle performance is good and the specific capacity is high. But at the same time, there are some problems, such as: poor high temperature resistance, large thermal shrinkage, poor wettability with electrolyte, and low electrical conductivity. Therefore, it is very important to develop new separator systems to improve battery performance.

Contents of the invention

The object of the present invention is to propose an ionic polymer electrolyte material and its preparation method and application in view of the above-mentioned deficiencies of the prior art.

The preparation method of an ionic polymer electrolyte material of the present invention comprises the following steps: 1) sulfonating polyether ether ketone to obtain sulfonated polyether ether ketone; 2) sulfonated polyetherether ether obtained in the ionization step 1) ketone.

Preferably, the degree of sulfonation of the sulfonated polyether ether ketone obtained in step 1) is 40%-95.0%.

Preferably, step 1) adopts concentrated sulfuric acid to sulfonate polyether ether ketone.

Preferably, the specific operation of using concentrated sulfuric acid to sulfonate polyether ether ketone: add the dried polyether ether ketone to concentrated sulfuric acid, stir and react at a certain temperature for a period of time, slowly pour the reaction solution into ice water, and Pour in while stirring until all the white filamentous solids are precipitated; filter, remove the filtrate, and keep the filter cake; wash with UP water until the washing liquid is neutral, and then dry the filter cake.

Preferably, in step 2), an alkaline solution formed of metal cations and hydroxides is used to ionize the sulfonated polyether ether ketone.

Preferably, the specific step of step 2) is to add sulfonated polyether ether ketone into a certain concentration of alkali solution and stir for a period of time to ensure that the solution is alkaline and the alkalinity does not change for a long time; filter the solution, filter the obtained The solid was washed to neutral and dried.

Preferably, the metal cation is one of lithium ions, potassium ions, sodium ions, magnesium ions, aluminum ions, zinc ions, manganese ions, mercury ions, cadmium ions and nickel ions.

An ionic polymer electrolyte material is prepared by the above preparation method.

A battery separator, prepared from the ionic polymer electrolyte material prepared by the above-mentioned preparation method.

The above-mentioned preparation method of a battery separator is prepared by solution casting method, electrospinning method, phase transfer method or template method.

In the present invention, polyetheretherketone is prepared through two steps of simple sulfonation and ionization to prepare a class of high-performance battery polymer electrolyte materials, and different degrees of sulfonation are obtained by controlling the temperature and time of sulfonation, and through the exchange of different metal ions , to obtain polymer electrolytes that can be applied to different batteries, including lithium-ion batteries, sodium-ion batteries, potassium-ion batteries, zinc-ion batteries, magnesium-ion batteries, etc. Since polyether ether ketone has a higher melting point, the battery separator prepared from this type of polymer electrolyte separator material has higher thermal dimensional stability. This type of polymer electrolyte membrane material has a variety of polar groups, such as C=O, O and SO3-, etc., so that this type of material has better compatibility with polar liquid electrolytes. In addition, this type of material itself has ion-conducting properties, which can effectively improve ion conductivity. Finally, because the sulfonate anions are suspended on the polymer skeleton, this type of polymer electrolyte separator material exhibits single-ion conductivity and has a high metal ion migration number. As a battery separator, the ion migration number of the polymer electrolyte can be increased. Greater improvement.

Description of drawings

Fig. 1 is the thermogravimetric curve diagram of the electrolyte separator prepared in Example 1 of the present invention;

Fig. 2 is the thermal dimensional stability test diagram of the electrolyte diaphragm prepared in Example 1 of the present invention;

Fig. 3 is the contact angle test diagram of the electrolyte separator prepared in Example 1 of the present invention;

Figure 4 is an electrochemical window diagram of the electrolyte separator prepared in Example 1 of the present invention;

Fig. 5 is a comparison diagram of the conductivity of the electrolyte diaphragm prepared in Example 1 of the present invention and the diaphragm prepared by commercial electrolyte and Li-SPEEK spinning membrane after adding commercial electrolyte;

Fig. 6 is the lithium ion migration figure of the electrolyte diaphragm prepared in Example 1 of the present invention;

Figure 7 is a diagram of the lithium ion migration number of PP/commercialized electrolyte separator;

Figure 8 is a diagram of the lithium ion transfer number after the Li-SPEEK spun membrane is added with a commercial electrolyte.

Detailed ways

The following are specific embodiments of the present invention and in conjunction with the accompanying drawings, the technical solutions of the present invention are further described, but the present invention is not limited to these embodiments.

Example 1

Preparation of sulfonated polyether ether ketone: Add 100 mL of concentrated sulfur to 10 g of polyether ether ketone dried in a vacuum oven at 60 °C, heat and stir at 38 °C for 5 h, 50 °C for 3 h, and 55 °C for 2 h, After the reaction is completed, cool to room temperature, slowly pour the above reaction solution into the ice-water mixture, and pour it while stirring until all the white filamentous solids are precipitated; filter, remove the filtrate, and keep the filter cake. Wash with UP water until neutral, dry in a blast oven at 60°C for 48h and vacuum dry at 80°C for 24h for use.

Ionized sulfonated polyether ether ketone: add 20mL of 1mol/L lithium hydroxide solution and stir for 2h, if the solution is detected to be acidic after 2h, add an appropriate amount of lithium hydroxide solution until the solution is alkaline and the alkalinity is no longer after stirring for a sufficient time changes happened. The solid was washed until neutral, dried in a blast oven at 60° C. for 48 hours, and then vacuum-dried at 80° C. for 24 hours to obtain an ionic polymer electrolyte material for use.

Preparation of the separator: the ionic polymer electrolyte prepared above was dissolved in N,N-dimethylformamide to form a uniform viscous solution with a concentration fraction of 29%, and then formed into a membrane by electrospinning.

Performance analysis:

1. Thermogravimetric analysis: An intelligent thermogravimetric analyzer (STA409PC, Germany NETZSCH) was used to analyze the thermal stability of the polymer. Under the protection of N ₂ atmosphere, the temperature was raised from room temperature to 800°C at a rate of 10°C min ^-1 . The curve of sample mass versus temperature was measured.

As shown in Figure 1, it can be seen from Figure 1 that the thermal decomposition temperature of the separator prepared in this embodiment is above 450°C, fully meeting the temperature requirements of the battery.

2. Thermal dimensional stability analysis: put the diaphragm on a glass plate, heat it with a heating plate, and record the diaphragm at room temperature, 50°C, 100°C, 150°C and 200°C for half an hour to see the shrinkage of the film diameter The shape of the diaphragm.

As shown in FIG. 2 , it can be seen from the figure that the separator prepared in this embodiment has good thermal dimensional stability, and there is no obvious thermal shrinkage at 200° C.

3. Contact angle test: use a JC2000D contact angle measuring instrument, use a micro-syringe to draw 1 drop of electrolyte EC/DMC on the diaphragm, take pictures after 3 seconds, and measure the contact angles of PP film and Li-SPEEK film respectively.

As shown in Figure 3, it can be seen from the figure that the separator of the present invention obtained by the electrospinning method completes the complete infiltration of the electrolyte within 3s, and the good wettability comes from the polar groups of this type of material, which has Good compatibility with polar liquid electrolytes.

4. Electrochemical window: soak the electrolyte diaphragm with a diameter of 19mm in EC/DMC (v:v=1:1) mixed solvent for 3 days, then use the stainless steel sheet as the working electrode, and the lithium sheet as the reference electrode, according to " Lithium sheet|diaphragm|stainless steel sheet" device structure to assemble the battery. The test range is -0.5V to 5V, and the sweep speed is 1mV s ^-1 .

As shown in Figure 4, it can be seen from the figure that within 5V, the separator prepared in this example has no oxidation peak, indicating that the separator prepared in this example has high electrochemical stability and can be applied to various batteries Among them, such as lithium iron phosphate, lithium cobalt oxide, and lithium manganese oxide even require high-voltage batteries.

5. Ionic conductivity: use electrochemical AC impedance spectroscopy, the scanning frequency is 1MHz to 1Hz, the oscillation voltage is 10mV, and the required impedance value is measured. The test temperature is from 25°C (room temperature) to 80°C. Soak the electrolyte diaphragm with a diameter of 16mm in the mixed solvent of EC/DMC (v:v=1:1), and take out the test device sandwiched between two stainless steel discs and assembled into a sandwich structure after 3 days, that is, "stainless steel sheet | Diaphragm|Stainless Steel Sheet". Conductivity was calculated using the following formula:

l is the thickness of the diaphragm (cm), R is the impedance (Ω) of the diaphragm measured by EIS, and A is the effective contact area of the diaphragm (cm ² ).

It can be seen from Fig. 5 that the Li-SPEEK separator prepared in Example 1 exhibited higher ionic conductivity, and after adding commercial electrolyte, it showed higher ionic conductivity than the traditional polyolefin separator.

6. Migration number of lithium ions: The number of migration of lithium ions is measured by the steady-state current method, a very small polarization voltage is given, and the impedance of the device is tested before and after the test (that is, before and after the formation of the passivation layer of the lithium electrode), and the frequency is 1MHz to 100Hz. The electrolyte separator with a diameter of 19mm was soaked in EC/DMC (v:v=1:1) mixed solvent for 3 days, and then assembled into a battery structure of "lithium sheet|diaphragm|lithium sheet". The ion migration number t+ is calculated by the following formula:

ΔV is the set polarization voltage, I ₀ and I _S represent the initial current and steady-state current, respectively, R ₀ and R _S represent the initial resistance and steady-state resistance of the passivation layer of the lithium electrode.

It can be seen from FIG. 6 that the lithium ion migration number of the Li-SPEEK spun membrane prepared in Example 1 is 0.89, showing single ion conductivity. Figure 7 shows the PP/commercialized electrolyte separator. The lithium ion migration number of the electrolyte system is only 0.28, showing dual ion conductivity. Figure 8 shows the lithium ion migration number of Li-SPEEK spinning membrane after adding commercial electrolyte. It can be seen from the figure that the lithium ion migration number of this system is 0.52, which is almost twice that of PP/commercial electrolyte separator, indicating that single ion The conductive Li-SPEEK separator helps to increase the lithium ion migration number of the electrolyte.

In summary, Embodiment 1 of the present invention provides an ionic polymer electrolyte that can be used for battery diaphragms, the film-forming method of the electrolyte diaphragm is electrospinning, and the polymer electrolyte film-forming material is sulfonated Polyether ether ketone has a high thermal decomposition temperature and high thermal dimensional stability, which can ensure the excellent thermal stability of the prepared polymer electrolyte. At the same time, under the condition of ensuring the excellent thermal stability of the separator, the ionized fiber filaments in the film-forming raw material also contain lithium ions, so as to improve the mobility and conductivity of lithium ions and subsequently increase the mobility of lithium ions number.

What is not involved above is applicable to the prior art.

Although some specific embodiments of the present invention have been described in detail by examples, those skilled in the art should understand that the above examples are only for illustration, rather than for limiting the scope of the present invention. Various modifications or additions or similar substitutions can be made to the described specific embodiments without departing from the direction of the present invention or exceeding the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent replacements, improvements, etc. made to the above implementations based on the technical essence of the present invention shall be included in the protection scope of the present invention.

Claims (10)

1. a kind of preparation method of Ionomer electrolyte, characterized by the following steps: 1) by polyethers ether Ketone sulfonation obtains sulfonated polyether-ether-ketone；2) ionization step 1) obtained sulfonated polyether-ether-ketone.

2. a kind of preparation method of Ionomer electrolyte as described in claim 1, it is characterised in that: step 1) The sulfonation degree of obtained sulfonated polyether-ether-ketone is 40%-95.0%.

3. a kind of preparation method of Ionomer electrolyte as described in claim 1, it is characterised in that: step 1) Using concentrated acid sulfonation polyether-ether-ketone.

4. a kind of preparation method of Ionomer electrolyte as claimed in claim 3, it is characterised in that: using dense The concrete operations of sulfuric acid sulfonation polyether-ether-ketone: it will be added in the concentrated sulfuric acid in dried polyether-ether-ketone, stir at a certain temperature Reaction a period of time, reaction solution is slowly poured into ice water, is poured into while stirring, until white stringy solids are whole It separates out；Filtrate is removed in filtering, retains filter cake；It is neutral, re-dry filter cake with UP water washing to cleaning solution.

5. a kind of preparation method of Ionomer electrolyte as described in claim 1, it is characterised in that: step 2) The middle aqueous slkali formed using metal cation and hydroxyl ionizes sulfonated polyether-ether-ketone.

6. a kind of preparation method of Ionomer electrolyte as claimed in claim 5, it is characterised in that: step 2) Comprise the concrete steps that sulfonated polyether-ether-ketone is added in certain density aqueous slkali stir a period of time after guarantee solution in alkali Property and for a long time alkalinity do not change；Filtering solution is dried after washing the solid being obtained by filtration to neutrality.

7. a kind of preparation method of Ionomer electrolyte as claimed in claim 5, it is characterised in that: the gold Belonging to cation is lithium ion, potassium ion, sodium ion, magnesium ion, aluminium ion, zinc ion, manganese ion, mercury ion, cadmium ion and nickel One of ion.

8. a kind of Ionomer electrolyte, it is characterised in that: by the described in any item preparation methods of claim 1-7 Preparation.

9. a kind of battery diaphragm, it is characterised in that: gathered by the ionic of the described in any item preparation method preparations of claim 1-7 The preparation of polymer electrolyte material.

10. a kind of preparation method of battery diaphragm as claimed in claim 9, it is characterised in that: use solution casting method, electrostatic Spin processes, phase transfer method or template preparation.