CN108110234B - A kind of conductive polymer hydrogel and its preparation method and application - Google Patents

Abstract

A conductive polymer hydrogel and a preparation method and application thereof. Dissolving an acrylic acid monomer and an aniline monomer in water or a water mixed solvent, standing and fully stirring; then weighing an initiator and preparing an aqueous solution; slowly dripping the prepared aqueous solution into the co-solution of the acrylic acid and the aniline monomer, and then controlling the reaction temperature to carry out copolymerization reaction for 0.5-5 hours under the protection of inert gas to obtain polyacrylic acid doped polyaniline stable polyaniline conductive polymer gel synthesized by a one-step method; then adding a precipitator for precipitation, filtering, washing and drying to obtain a sample. The conductive polymer gel is applied as a positive electrode material to prepare a lithium battery, and has good charge-discharge performance, cycle stability and capacity retention rate when being used as a positive electrode material of a lithium ion battery.

Description

A kind of conductive polymer hydrogel and its preparation method and application

technical field

The present invention relates to a hydrogel and its preparation method and application, in particular to a conductive polymer hydrogel and its preparation method and application.

Background technique

Super absorbent polymer is a new type of functional polymer material with moderate cross-linking and three-dimensional network structure. It can absorb tens or even thousands of times its own weight in water, and the absorbed water will not overflow even under pressure. . Superabsorbent polymers were first used in agriculture and health care 30 years ago, and have gradually expanded to other fields where better water absorption and retention properties are required. In recent years, researchers on superabsorbent polymers have mainly developed new uses for them, such as conductive materials, biomaterials, sensors, drug release materials, and wave absorbing materials. At present, it has become a research hotspot to prepare multifunctional superabsorbent polymers by modification, grafting, copolymerization and other methods to meet practical needs.

However, there are few reports on the preparation of conducting polymers and hydrogels based on superabsorbent polymers. Due to the advantages of high electrical conductivity, colloidal stability, low price and simple preparation process, conductive hydrogels can be used to prepare fuel cells, capacitors, fuel-sensitive solar cells and rechargeable lithium batteries. Polyaniline is a highly conductive polymer, and new conductive hydrogels can be prepared by combining with polyacrylate superabsorbent polymers. However, the preparation of conductive polyaniline hydrogel usually adopts a two-step method, that is, firstly prepare a water-soluble polymer gel, and then conduct the polymerization process of polyaniline to prepare conductive polyaniline hydrogel. In the post-polymerization process of polyaniline, an inorganic small molecular acid needs to be introduced as a doping acid, and the loss of the doping acid in the subsequent use process and the influence on the electrical properties of the polyaniline gel cannot be guaranteed. In this paper, a polyacrylic acid/polyaniline conductive hydrogel was synthesized by a one-step aqueous solution polymerization method. Because the aniline monomer and the acrylic monomer are mixed in the early stage of the reaction, and then the polyacrylic acid-doped polyaniline conductive polymer gel is formed in one step by a copolymerization method, and the doping rate and electrical properties of the material are improved. It is a promising new method for preparing stable conductive polymer hydrogels. The stable polyaniline conductivity and unique hydrogel adhesion are expected to be applied in the electrode materials of organic lithium batteries.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a conductive polymer hydrogel and a preparation method and application thereof. The polyaniline/polyacrylic acid conductive polymer gel is prepared by a one-step method and applied to a positive electrode material of a lithium battery; the polyaniline prepared by a one-step method The conductive polymer gel has high organic acid doping degree and stable electrical properties, and the prepared hydrogel can be used as a potential cathode material for organic lithium-ion batteries.

The purpose of this invention is to realize through the following technical solutions:

A conductive polymer hydrogel, the conductive polymer hydrogel is a polyacrylic acid/polyaniline conductive polymer gel with structural and electrochemical stability, characterized in that its chemical structure is such as (1) shown:

A method for preparing conductive polymer hydrogel, the preparation process adopts one-step co-initiated polymerization to prepare conductive polymer gel; the method includes the following preparation process:

Dissolve acrylic monomer and aniline monomer in water or water mixed solvent, stand still and fully stir; then, weigh the initiator and configure an aqueous solution; slowly add the configured aqueous solution dropwise to the above-mentioned co-solution of acrylic acid and aniline monomer , and then control the reaction temperature and carry out the copolymerization reaction under the protection of inert gas for 0.5-5 hours to obtain the polyacrylic acid-doped polyaniline-stabilized polyaniline conductive polymer gel synthesized by one-step method; then add a precipitant for precipitation, filter , washed and dried to obtain the sample.

In the method for preparing a conductive polymer hydrogel, an inert gas, such as nitrogen or argon, is used for protection during the synthesis of the polyacrylic acid/polyaniline conductive polymer gel material.

In the method for preparing a conductive polymer hydrogel, the aqueous solvent used in the synthesis process of the polyacrylic acid/polyaniline gel material includes: water, acetone/water mixed solution, ethanol and water mixed solution.

In the method for preparing a conductive polymer hydrogel, the oxidants used in the synthesis process of the conductive polymer gel material are ammonium persulfate, potassium persulfate, FeCl ₃ , and H ₂ O ₂ .

In the method for preparing a conductive polymer hydrogel, in the process of synthesizing the conductive polymer gel material, oxidant: monomer=0.1-1 mol/mol; the reaction time is 0.5-5 h; the reaction temperature is -20 ~60℃; acetone, methanol and ethanol are used as precipitants.

An application of a conductive polymer hydrogel, the prepared polyacrylic acid/polyaniline gel material is used as a positive electrode material of a lithium battery; the preparation process of a positive electrode piece of a lithium battery is: using an aqueous solvent coating method to prepare a positive electrode on the surface of an aluminum foil Electrode sheet; disperse polyacrylic acid/polyaniline gel active material: conductive acetylene black = mass ratio 2~8:2~5, disperse in water+alcohol mixed solvent and grind uniformly into a viscous coating on clean aluminum foil, then It was dried in a vacuum drying oven.

The advantages and effects of the present invention are:

(1) Compared with the reported step-by-step preparation of polyacrylic acid/polyaniline conductive polymer gel, the polyaniline conductive polymer gel prepared by one-step method has high organic acid doping degree, stable electrical properties, and simple preparation method, etc. Features.

(2) Compared with the reported inorganic acid-doped polyaniline cathode material, the polyacrylic acid-doped polyaniline gel material prepared by the one-step method of the present invention has an actual specific capacity of 131.2 mAh/g; at the same time, the electrode prepared The electrode has the advantages of improved cycle stability and improved self-discharge performance of the prepared electrode material. Therefore, the polyacrylic acid/polyaniline conductive polymer hydrogel prepared by one-step method can be used as a very potential cathode material for organic lithium-ion battery cathode materials.

Description of drawings

Fig.1 The first charge-discharge curves of polyacrylic acid/polyaniline conductive polymer gel at a charge-discharge rate of 20 mA/g (voltage range: 2.5~4.2 V vs. Li/Li ⁺ );

Figure 2. Cycling stability performance of the polyacrylic acid/polyaniline conductive polymer gel cathode material at a charge-discharge rate of 20 mA/g (voltage range: 2.5~4.2 V vs. Li/Li ⁺ ).

Detailed ways

The present invention will be described in detail below with reference to the embodiments shown in the accompanying drawings.

Fig. 1 The first charge-discharge curves of polyacrylic acid/polyaniline gel polymer (a) and PANI-HCl (b) at a rate of 17 mA·g ^-1 .

Figure 2. Cycling performance of polyacrylic acid/polyaniline gel (a) and PANI-HCl (b) discharged at a rate of 17 mA·g ⁻¹ .

The polyacrylic acid/polyaniline conductive polymer hydrogel of the present invention has the chemical structure shown in (1):

The present invention also provides a one-step preparation method of the polyacrylic acid/polyaniline conductive polyaniline. The method comprises the following steps: dissolving a certain amount of acrylic monomer and aniline monomer in a certain volume of water or a mixed solvent of water, and then static for a certain amount of time. time and stir well. Then, a certain amount of initiator is weighed and an aqueous solution of a certain concentration is prepared. The prepared aqueous solution is slowly added dropwise to the above-mentioned co-solution of acrylic acid and aniline monomer, and then the reaction temperature is controlled within a certain range and the copolymerization reaction is carried out under the protection of an inert gas for 0.5-5 hours. A polyacrylic acid-doped polyaniline-stabilized polyaniline conductive polymer gel synthesized by one-step method was obtained. Then a precipitant was added for precipitation, filtered, washed and dried to obtain the sample.

In the one-step preparation method, the inert gas used includes nitrogen, argon and other gases, preferably argon.

In the method, the aqueous solvent used in the reaction mainly includes water, acetone/water mixed solution, ethanol and water mixed solution, preferably water.

In the method, the oxidizing agent mainly includes ammonium persulfate, potassium persulfate, FeCl ₃ , H ₂ O ₂ , etc., preferably ammonium persulfate.

Further, the oxidant in the reaction feed: monomer=0.1~1 mol/mol; the reaction time is 0.5~5 h; the reaction temperature is -20~60°C; the precipitating agent is acetone, methanol, ethanol, etc.

The invention also provides an application of the prepared polyaniline gel as a positive electrode active material for a lithium battery. Specifically, the preparation process of the positive electrode and the battery assembly process are as follows:

Electrode preparation: A positive electrode sheet was prepared on the surface of aluminum foil by using water as solvent coating method. Disperse the polyacrylic acid/polyaniline gel active material: conductive acetylene black in a mixed solvent of water + alcohol and grind it uniformly to form a viscous coating on a clean aluminum foil, and then dry it in a vacuum drying oven.

Further, the mass composition of the electrode material is, active material polymer gel: conductive agent acetylene black=2~8:2~5, preferably 5~7:3~4.

Assembly of the battery: The conventional battery assembly process is adopted. Specifically, the CR2032 battery device system was used to test the electrochemical performance and charge-discharge performance of the battery. Lithium was used as the negative and reference electrode, the electrolyte was 1 M LiPF ₆ in EC:DMC = 1:1 (v/v) solution, and the separator was an industrially used polypropylene microporous membrane (Celgard 2300) prepared before The electrode is the positive electrode, which is assembled into a CR2032 simulated half-cell in a glove box in an argon atmosphere (both water and oxygen values are below 1 ppm). And put it in the battery test system for constant current charge and discharge test and rate performance test.

The present invention applies the polyaniline conductive polymer gel prepared by the one-step method to the lithium ion battery as the positive electrode material of the lithium ion battery for the first time, and assembles it into a simulated battery device for testing and obtains better battery performance.

Example 1

Preparation of polyacrylic acid/polyaniline conductive polymer gel

At room temperature, 15 g of acrylic monomer, 0.4656 g of aniline monomer, and 0.0308 g of cross-linking agent were dissolved in 50 ml of distilled water to form a mixed solution of aniline acrylate (as shown in Figure 1). The mixture was stirred uniformly and placed in a 50 ^o C water bath for heating and stirring, 10 ml of solution containing 0.5705 g of initiator ammonium persulfate was added dropwise, and the reaction was stirred under the protection of inert argon for 1 h. The reaction polymer gel was precipitated with a large amount of acetone, filtered, washed and dried to obtain a polyacrylic acid/polyaniline hydrogel product.

Example 2

Electrode preparation and battery assembly

(1) Preparation of electrodes. Electrodes were prepared on the surface of aluminum foil by coating method. Dissolve active material polymer powder: conductive agent acetylene black = mass ratio 7:3 in water to form a viscous liquid. The liquid was then coated on clean aluminum foil with a 90 nm doctor blade and vacuum dried at 60 ^o C until the film quality remained unchanged.

(2) Assembly of the battery. In this paper, the CR2032 battery device system is mainly used to test the electrochemical performance and charge-discharge performance of the battery. Lithium was used as the negative and reference electrode, the electrolyte was 1 M LiPF6 in EC:DMC = 1:1 (v/v) solution, and the separator was an industrially used polypropylene microporous membrane (Celgard 2300). As the positive electrode, a CR2032 simulated half-cell was assembled in a glove box in an argon atmosphere (both water and oxygen values were below 1 ppm). Before testing, put the assembled battery in a desiccator for 12 h. This move is to make the electrolyte and the pole piece better infiltrate, so as to make the test data more stable. The electrochemical performance of the prepared battery was tested at a charge-discharge rate of 20 mA/g in 1mol/L LiPF6 EC/DMC (V/V, 1:1) electrolyte at 2.5 V-4.2 V Charge-discharge and cycle performance tests are performed within the voltage range.

The battery performance test showed that the polyacrylic acid/polyaniline conductive polymer gel as the battery cathode material exhibited a high specific discharge capacity (131.2 mAh/g) (Fig. 1) and had improved cycling stability (Fig. 2). The storage performance of the assembled simulated coin cell was improved and enhanced, and the capacity retention rate was 70% of the initial capacity after 2 months of storage (compared to the 52% capacity retention rate of the conventional hydrochloric acid-doped polyaniline cathode).

Claims (5)

1. a method for preparing conductive polymer hydrogel, characterized in that the preparation process adopts one-step co-initiated polymerization to prepare conductive polymer gel; the method comprises the following preparation process: Dissolve acrylic monomer and aniline monomer in water or water mixed solvent, stand still and fully stir; then, weigh the initiator and configure an aqueous solution; slowly add the configured aqueous solution dropwise to the above-mentioned co-solution of acrylic acid and aniline monomer , then control the reaction temperature, and carry out the copolymerization reaction under the protection of inert gas for 0.5-5 hours to obtain the polyacrylic acid-doped polyaniline-stabilized polyaniline conductive polymer gel synthesized by one-step method; then add a precipitant for precipitation, filter , washed and dried to obtain the sample. 2 . The method for preparing a conductive polymer hydrogel according to claim 1 , wherein the inert gas is argon. 3 . 3 . The method for preparing a conductive polymer hydrogel according to claim 1 , wherein the water or water mixed solvent comprises: one of water, acetone/water mixed solution, ethanol and water mixed solution. 4 . 4 . The method for preparing a conductive polymer hydrogel according to claim 1 , wherein the initiator is one of ammonium persulfate, potassium persulfate, FeCl ₃ and H ₂ O ₂ . 5 . 5. a kind of conductive polymer hydrogel preparation method according to claim 1, is characterized in that, in the described conductive polymer gel material synthesis process initiator: monomer=0.1～1 mol/mol; Reaction time for 0.5~5 h; the reaction temperature is -20~60℃; the precipitating agent is one of acetone, methanol and ethanol.

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