阅读说明：本技术 一种氧化石墨烯/聚苯胺/二氧化锰复合电极及其制备方法和在海水电池中的应用 (Graphene oxide/polyaniline/manganese dioxide composite electrode, preparation method thereof and application thereof in seawater battery ) 是由 邓姝皓 袁莉君 陈永波 周富威 方文强 于 2020-03-24 设计创作，主要内容包括：本发明公开了一种氧化石墨烯/聚苯胺/二氧化锰复合电极及其制备方法和在海水电池中的应用。复合电极的制备是以石墨纸作为阳极,不锈钢板作为阴极,无机酸溶液作为电解液,进行电氧化处理石墨纸,再以氧化石墨纸作为阳极,不锈钢板作为阴极,苯胺-有机酸-无机酸-二价锰盐混合溶液作为电解液,在氧化石墨纸上同时电沉积聚苯胺和二氧化锰,即得能量密度高、极化作用小、比表面积大、稳定性好的复合电极,将复合电极用于海水电池,表现出高比容量、高比能量等优点。(The invention discloses a graphene oxide/polyaniline/manganese dioxide composite electrode, a preparation method thereof and application thereof in a seawater battery. The preparation method of the composite electrode comprises the steps of taking graphite paper as an anode, taking a stainless steel plate as a cathode, taking an inorganic acid solution as an electrolyte, carrying out electrooxidation treatment on the graphite paper, taking oxidized graphite paper as the anode, taking the stainless steel plate as the cathode, taking an aniline-organic acid-inorganic acid-divalent manganese salt mixed solution as the electrolyte, and electrodepositing polyaniline and manganese dioxide on the oxidized graphite paper simultaneously to obtain the composite electrode which is high in energy density, small in polarization, large in specific surface area and good in stability.)

1. A method for preparing a graphite oxide paper/polyaniline/manganese dioxide composite electrode by electrochemical in-situ polymerization is characterized by comprising the following steps: carrying out electrooxidation treatment on graphite paper by taking the graphite paper as an anode, a stainless steel plate as a cathode and an inorganic acid solution as electrolyte to obtain graphene oxide paper; and then, taking graphite oxide paper as an anode, a stainless steel plate as a cathode, and a mixed solution of aniline-organic acid-inorganic acid-divalent manganese salt as an electrolyte, and electrodepositing polyaniline and manganese dioxide on the graphite oxide paper at the same time to obtain the composite material.

2. The method for preparing the graphene oxide/polyaniline/manganese dioxide composite electrode by electrochemical in-situ polymerization according to claim 1, wherein the graphene oxide/polyaniline/manganese dioxide composite electrode comprises the following steps: the conditions of the electrooxidation treatment are as follows: the temperature is 10-50 ℃, and the current density is 5-50 mA-cm^-2The electrooxidation time is 5-100 min; the electric oxidation adopts a direct current power supply orA pulse power supply; the direct current power supply is a constant voltage or constant current direct current power supply; the pulse period of the pulse power supply is 1-200 ms, and the duty ratio is 0.1-0.8.

3. The method for preparing the graphene oxide/polyaniline/manganese dioxide composite electrode through electrochemical in-situ polymerization according to claim 1, wherein the concentration of the inorganic acid solution is 0.1-3 mol/L, and the inorganic acid solution is at least one selected from nitric acid, sulfuric acid, hydrochloric acid and phosphoric acid.

4. The method for preparing the graphene oxide/polyaniline/manganese dioxide composite electrode by electrochemical in-situ polymerization according to claim 1, wherein the graphene oxide/polyaniline/manganese dioxide composite electrode comprises the following steps: the thickness of the graphite paper is 0.01-5 mm.

5. The method for preparing the graphene oxide/polyaniline/manganese dioxide composite electrode by electrochemical in-situ polymerization according to claim 1, wherein the graphene oxide/polyaniline/manganese dioxide composite electrode comprises the following steps: the conditions of the electrodeposition are as follows: the current density is 10-60 mA-cm^-2The electrodeposition time is 10-50 min, and the temperature is 10-60 ℃.

6. The method for preparing the graphene oxide/polyaniline/manganese dioxide composite electrode by electrochemical in-situ polymerization according to claim 1 or 5, wherein: the electrodeposition adopts a direct current power supply or a pulse power supply; the direct current power supply is a constant voltage or constant current direct current power supply; the pulse period of the pulse power supply is 1-200 ms, and the duty ratio is 0.1-0.8.

7. The method for preparing the graphene oxide/polyaniline/manganese dioxide composite electrode through electrochemical in-situ polymerization according to claim 1, wherein the concentration of aniline in the aniline-organic acid-inorganic acid-manganous salt mixed solution is 0.1-3 mol/L, the concentration of manganous salt is 1-5 mol/L, the concentration of inorganic acid is 0.3-3 mol/L, the concentration of organic acid is 10-50 g/L, the inorganic acid is at least one selected from sulfuric acid, hydrochloric acid and perchloric acid, the organic acid is at least one selected from sulfosalicylic acid, sodium dodecyl benzene sulfonate, camphorsulfonic acid and p-methylbenzenesulfonic acid, and the manganous salt is at least one selected from manganese chloride, manganese sulfate, manganese acetate and manganese perchlorate.

8. A graphene oxide/polyaniline/manganese dioxide composite electrode is characterized in that: prepared by the method of any one of claims 1 to 7.

9. The application of the graphene oxide/polyaniline/manganese dioxide composite electrode as claimed in claim 8, wherein: the method is applied to seawater batteries.

10. The application of the graphene oxide/polyaniline/manganese dioxide composite electrode according to claim 9, wherein the graphene oxide/polyaniline/manganese dioxide composite electrode comprises: the graphene oxide/polyaniline/manganese dioxide composite electrode is used as a positive electrode, the magnesium alloy is used as a negative electrode, and seawater is used as electrolyte to form the seawater battery.

Technical Field

The invention relates to a seawater battery anode, in particular to a composite anode prepared by in-situ polymerization by taking graphite oxide paper as a matrix and a conductive agent, manganese dioxide as a stabilizer and conductive polyaniline as an active substance, and also relates to application of the composite anode in a seawater battery, belonging to the technical field of seawater battery preparation.

Background

Polyaniline is used as a conductive polymer with excellent performances such as light weight, low price, large specific surface area, good stability, simple and convenient synthesis method, adjustable and controllable conductive capacity and the like, and the theoretical energy density is more than 500 Wh/kg^-1The composite material is expected to replace traditional positive electrode materials such as noble metals, noble metal salts, metal oxides and the like which have high cost, large specific gravity, poor conductivity and long activation time, and is applied to high-performance seawater batteries.

Polyaniline is insoluble in various solvents and poor in thermal processing performance, and related electrodes are generally pressed under high pressure, but the method can cause electrolyte to be difficult to permeate into the electrodes, so that active substances in the electrodes are difficult to participate in reaction, and the utilization rate of the active substances is reduced. In a magnesium/polyaniline seawater battery system, in the discharging process, the polyaniline has a de-doping phenomenon, the conductivity of the polyaniline is reduced, so that the internal resistance of the battery is increased, the electrode reaction is difficult to go deep into the battery, and the utilization rate of active substances is low.

The positive electrode of the polyaniline seawater battery mentioned in the Chinese patent (application number 201810052098.3) is a polyaniline electrode prepared by pressing, and in order to maintain the stable structure of the electrode during use and the compact electrode pressure, electrolyte is difficult to enter during reaction, and only can react with polyaniline on the surface of the electrode, so that the utilization rate is limited. In addition, the outer polyaniline layer of the pressed polyaniline electrode is subjected to reaction to cause the dedoping of materials, the conductivity is poor, the internal resistance is obviously increased, and the polyaniline in the inner layer is seriously influenced to participate in the reaction, so that only the polyaniline on the surface participates in the reaction when the polyaniline electrode is subjected to electrochemical reaction, the discharge capacity of the polyaniline electrode is not high enough, and the excellent battery performance of the polyaniline cannot be shown.

Disclosure of Invention

Aiming at the defects of insufficient utilization rate of active substances and serious electrode polarization in the preparation process of the polyaniline positive electrode of the existing seawater battery, the first purpose of the invention is to provide a method for preparing a graphene oxide/polyaniline/manganese dioxide composite electrode by electrochemical in-situ polymerization.

The second purpose of the invention is to provide a seawater battery anode which has the advantages of light weight, low price, environmental protection, high energy density, small polarization, large specific surface area and good stability.

The third purpose of the invention is to provide an application of the graphene oxide/polyaniline/manganese dioxide composite electrode, and the seawater battery with large specific capacity and high specific energy can be obtained by using the graphene oxide/polyaniline/manganese dioxide composite electrode as the anode of the seawater battery.

In order to achieve the technical purpose, the invention provides a method for preparing a graphite oxide paper/polyaniline/manganese dioxide composite electrode by electrochemical in-situ polymerization, which comprises the steps of carrying out electrooxidation treatment on graphite paper by taking the graphite paper as an anode, a stainless steel plate as a cathode and an inorganic acid solution as an electrolyte to obtain graphene oxide paper; and then, taking graphite oxide paper as an anode, a stainless steel plate as a cathode, and a mixed solution of aniline-organic acid-inorganic acid-divalent manganese salt as an electrolyte, and electrodepositing polyaniline and manganese dioxide on the graphite oxide paper at the same time to obtain the composite material.

According to the technical scheme, graphene paper is oxidized in situ by an electrochemical method, and then the graphene oxide paper is used as an anode to compound a polyaniline active material and a manganese dioxide stabilizer in situ by the electrochemical method, the graphene oxide has a large specific surface area and is rich in polar groups on the surface, so that the generated polyaniline can be completely spread on the surface of the graphene oxide paper to generate a uniform polyaniline film layer, and the full contact between the active polyaniline and an electrolyte is facilitated.

According to the technical scheme, graphite paper is oxidized on the electrochemical surface to form oxygen-containing functional groups which are large in specific surface area, carboxyl, epoxy, hydroxyl and the like are arranged on the surface, physical and chemical bonding effects of polyaniline and the surface of graphene oxide are utilized, in-situ compounding of the graphene oxide paper and the polyaniline is facilitated, and the utilization rate of the electrode can be improved to the maximum extent by improving the specific surface area of the polyaniline. Therefore, the polyaniline composite material prepared by taking the graphene oxide paper as the substrate is directly used as an electrode, the graphite paper is used as an electrode support, the effect of improving the specific surface area of the electrode is also achieved, and the polyaniline composite can be completely spread on the electrode support, so that the utilization rate of active substances is improved. The composite of polyaniline and manganese dioxide is used as the active material of positive electrode of battery, and because the main reaction on the polyaniline electrode is the dedoping of polyaniline and the reduction of oxygen, the side reaction separates out H₂，H₂The manganese dioxide is used as an effective electrode depolarizer and stabilizer, can reduce the evolution of hydrogen, and can absorb H₂The polarization effect is reduced; the structure of the electrode can be improved, and the stability of the electrode can be improved.

In a preferred embodiment, the conditions of the electrooxidation treatment are as follows: the temperature is 10-50 ℃, and the current density is 5-50 mA-cm^-2The oxidation time is 5-100 min. More preferred conditions for the electrooxidation treatment are: the temperature is 35-45 ℃, and the current density is 10-20 mA-cm^-2The oxidation time is 50-100 min。

In a preferable scheme, a direct current power supply or a pulse power supply is adopted in the electro-oxidation treatment process; the direct current power supply is a constant voltage or constant current direct current power supply; the pulse period of the pulse power supply is 1-200 ms, and the duty ratio is 0.1-0.95.

Preferably, the concentration of the inorganic acid solution is 0.1-3 mol/L, and the inorganic acid solution is at least one selected from nitric acid, sulfuric acid, hydrochloric acid and phosphoric acid, more preferably, the concentration of the inorganic acid solution is 1-2 mol/L.

In the preferable scheme, the thickness of the graphite paper is 0.01-5 mm. The thickness of the preferred graphite paper is 1-3 mm, and the electrodeposition conditions are as follows: the current density is 10-60 mA-cm^-2The electrodeposition time is 10-50 min, and the temperature is 10-60 ℃. Preferred electrodeposition conditions are: the current density is 10-30 mA-cm^-2The electrodeposition time is 10-30 min, and the temperature is 40-50 ℃.

In a preferable scheme, a direct current power supply or a pulse power supply is adopted in the electrodeposition process; the direct current power supply is a constant voltage or constant current direct current power supply; the pulse period of the pulse power supply is 1-200 ms, and the duty ratio is 0.1-0.95.

Preferably, the concentration of aniline in the aniline-organic acid-inorganic acid-divalent manganese salt mixed solution is 0.1-3 mol/L, the concentration of divalent manganese salt is 1-5 mol/L, the concentration of inorganic acid is 0.3-3 mol/L, the concentration of organic acid is 10-50 g/L, the concentration of aniline is preferably 0.5-1.5 mol/L, the concentration of divalent manganese salt is preferably 2-4 mol/L, the concentration of inorganic acid is preferably 1-3 mol/L, and the concentration of organic acid is preferably 20-40 g/L.

Preferably, the inorganic acid is an inorganic acid commonly used in the art, such as at least one selected from sulfuric acid, hydrochloric acid, and perchloric acid.

Preferably, the organic acid is an organic carboxylic acid commonly used in the art, such as at least one selected from sulfosalicylic acid, sodium dodecylbenzene sulfonate, camphorsulfonic acid, and p-methyl benzene sulfonic acid.

Preferably, the manganous salt is common manganous salt in the field, such as at least one selected from manganese chloride, manganese sulfate, manganese acetate and manganese perchlorate.

According to the technical scheme, the graphite paper is oxidized in situ through electrochemistry, polyaniline is polymerized in situ, the oxidized graphene paper is large in specific area and contains more active functional groups, in-situ compounding of polyaniline and manganese dioxide is facilitated, a large number of reaction active points are provided for aniline polymerization, polyaniline active materials can be in full contact with electrolyte, and the utilization rate of active substances is improved.

The invention also provides a graphene oxide/polyaniline/manganese dioxide composite electrode which is prepared by the method. In the composite electrode, polyaniline is used as an active substance, graphene oxide is used as a conductive agent, and manganese dioxide is used as a stabilizer. H precipitation by side reaction on polyaniline as active material of composite electrode₂，H₂The reaction on the positive electrode is hindered by the adhesion of the manganese dioxide to the electrode, so that the internal resistance of the battery is increased to cause voltage drop, and the introduction of the manganese dioxide can effectively depolarize, MnO₂Can absorb H₂And the polarization effect is reduced, so that the structure of the electrode is improved, and the stability of the electrode is improved. The graphene oxide paper is introduced, and a large amount of oxygen-containing functional groups such as carboxyl, epoxy, hydroxyl and the like on the surface of the graphene oxide paper are utilized, so that not only is the in-situ compounding of polyaniline, manganese dioxide and graphene oxide facilitated, but also the graphene oxide can be used as a conductive agent of polyaniline, particularly a large amount of active groups on the surface of the graphene oxide provide a large amount of reaction active points for polyaniline monomers in a solution, the specific surface area of a polyaniline electrode is facilitated to be increased, the polyaniline active material can be in full contact with electrolyte, and the utilization rate of active substances is increased.

The invention also provides an application of the graphene oxide/polyaniline/manganese dioxide composite electrode, which is applied to a seawater battery.

In the preferred scheme, the graphene oxide/polyaniline/manganese dioxide composite electrode is used as a positive electrode, the magnesium alloy is used as a negative electrode, and seawater is used as an electrolyte to form the seawater battery. Magnesium alloys are common alloy systems in the art, such as magnesium aluminum alloys or magnesium zinc alloys.

The seawater battery prepared by the invention uses the composite anode and the magnesium alloy cathode to form the seawater battery, discharges in 3.5 wt% sodium chloride solution, and has constant current discharge current of 6.25mA/cm^-2And cutoff voltage 1.0V. The open-circuit voltage of the seawater battery is 1.8V-2.2V, 6.25mA/cm^-2Constant current discharge, the average discharge voltage is 1.35V-1.6V, the specific capacity of the battery is 172-300 mAh/g, and the specific energy is 230-450 mWh/g.

The process for preparing the graphite oxide paper/polyaniline/manganese dioxide composite electrode comprises the following specific steps:

the method comprises the following steps: oxidation treatment of graphite paper

The process of oxidizing graphite paper electrochemically includes oxidizing graphite paper with electrolyte of inorganic acid in concentration of 0.1-3 mol/L and selected from at least one of nitric acid and sulfuric acid, stainless steel plate as cathode and graphite paper as anode in thickness of 0.01-5 mm at 10-60 deg.c, and electrochemical oxidation at current density of 5-50 mA-cm^-2The oxidation time is 5-100 min;

step two: preparation of the electrodes

The process of preparing the graphite oxide paper/polyaniline/manganese dioxide composite electrode by electrochemical in-situ polymerization comprises the steps of enabling the concentration of inorganic acid in electrolyte to be 0.3-3 mol/L, enabling the concentration of organic acid to be 10-50 g/L, enabling the concentration of aniline to be 0.1-3 mol/L, enabling the concentration of manganese sulfate to be 1-5 mol/L, enabling an anode to be graphite oxide paper, enabling a cathode to be a stainless steel plate, maintaining the temperature of the electrolyte to be 10-60 ℃, and preparing the graphite oxide paper/polyaniline/manganese dioxide composite electrode by the electrochemical in-situ polymerization method, wherein the current density is 10-60 mA-cm^-2The deposition time is 10-50 min;

step three: battery discharge test

Discharging the prepared anode and magnesium alloy formed seawater battery in 3.5 wt% sodium chloride solution at 6.25mA/cm^-2Constant current discharge, cut-off voltage 1.0V; the open circuit voltage of the battery is 1.8V-2.2V, the average discharge voltage is 1.35V-1.6V, and the specific capacity of the battery is 172-300 mAh/g, and the specific energy is 230-450 mWh/g.

Compared with the prior art, the technical scheme of the invention has the beneficial technical effects that:

the invention provides a composite polyaniline electrode which is prepared by oxidizing graphene paper electrochemically and realizing in-situ compounding of graphene oxide, polyaniline and manganese dioxide, can realize uniform loading of polyaniline active materials on the surface of conductive graphene, greatly improves the contact area of polyaniline electrode materials and electrolyte, and improves the utilization rate of active substances.

The graphite oxide paper/polyaniline/manganese dioxide composite electrode provided by the invention has the advantages of light weight, low price, environmental friendliness, high energy density, small polarization effect, large specific surface area and good stability.

The graphene oxide/polyaniline/manganese dioxide composite electrode provided by the invention is applied to the anode of a seawater battery, and has the characteristics of large specific capacity and high specific energy, for example, the open-circuit voltage of the seawater battery is 1.8V-2.2V, the average discharge voltage is 1.35V-1.6V, and the specific energy of the battery is 172-300 mAh/g and 230-450 mWh/g.

The invention adopts an electrochemical in-situ polymerization method to prepare the graphite oxide paper/polyaniline/manganese dioxide composite electrode for the first time, has obvious technical advantages compared with the prior anode prepared by direct pressing, and mainly shows simple preparation (only an electrochemical mode and one-step forming) and environmental protection (no heavy metal pollution such as lead and the like).

Detailed Description

The following detailed description of embodiments of the present invention is provided for illustrative purposes and is intended to be merely illustrative of the invention and not limiting of the scope of the invention as claimed. Of course, a person skilled in the art may, on the basis of the following description, propose corresponding modifications or variations, which are intended to be included within the scope of the present invention.

Performance characterization of the electrodes:

the prepared polyaniline electrode and magnesium alloy form a seawater battery, the battery is subjected to discharge performance test by using a battery capacity tester, and 6.25mA/cm is set^-2Constant current discharge, cutoff voltage 1.0V, and summary and calculation of open circuit voltage, discharge time, battery capacity and specific energy with battery.