阅读说明：本技术 一种不需金属集流体的电化学储能电极片 (Electrochemical energy storage electrode plate without metal current collector ) 是由 刘金章 张宗伟 于 2019-09-26 设计创作，主要内容包括：本发明涉及一种基于碳材料的自支撑电化学储能电极片,组分包短切碳纤维、碳纳米管、多孔活性炭、和粘合剂。将碳纤维和碳纳米管进行表面功能化处理后,与活性炭和粘合剂在乙醇中混合,得到原料,然后压片成型,干燥后得到自支撑的储能电极片,无需金属箔片集流体。短切碳纤维和碳纳米管起到增加电极片的机械强度和提高导电之作用,而多孔活性炭则是对电化学储能起主要作用。本发明提供的以碳材料为基的集流体与电极一体化的电极片,具有操作简便、性能稳定的优点,且不含金属集流体,适合水系储能器件。(The invention relates to a self-supporting electrochemical energy storage electrode plate based on a carbon material, which comprises the components of short carbon fibers, carbon nanotubes, porous activated carbon and an adhesive. After surface functionalization treatment is carried out on carbon fibers and carbon nanotubes, the carbon fibers and the carbon nanotubes are mixed with active carbon and an adhesive in ethanol to obtain a raw material, then tabletting and forming are carried out, and the self-supporting energy storage electrode slice is obtained after drying without a metal foil current collector. The chopped carbon fibers and the carbon nanotubes play a role in increasing the mechanical strength of the electrode plate and improving the electric conductivity, and the porous activated carbon plays a main role in electrochemical energy storage. The electrode plate integrating the carbon-based current collector and the electrode has the advantages of simplicity and convenience in operation and stable performance, does not contain a metal current collector, and is suitable for a water system energy storage device.)

1. An electrochemical energy storage electrode plate without a metal current collector is characterized by selection of materials and a preparation method.

1) Selecting short carbon fibers with the length of 3mm, and carrying out surface plasma treatment on the short carbon fibers by using a plasma cleaning machine.

2) Multiwalled carbon nanotubes are added to build a conductive network in the electrode sheet. The multi-wall carbon nano tube is treated by concentrated nitric acid, and is treated for 5 hours at the temperature of 150 ℃ by a hydrothermal method. Thus, the carbon nano tube has oxygen-containing groups on the surface and has better dispersibility.

3) Optimizing the mass ratio of the components and uniformly mixing. Dispersing carbon fiber, carbon nanotube and active carbon in ethanol at a ratio of 1:2:2, adding 10% of binder (PTFE emulsion), and ultrasonic mixing.

4) And (6) tabletting. And filtering the mixture to obtain a filter cake, transferring the filter cake into a 70 ℃ oven for drying, pressing the dried filter cake into a sheet with the thickness of 2mm by using a tablet press, and then rolling the sheet into a compact sheet with the thickness of 0.5mm by using a roller press.

2. The electrochemical energy storage electrode plate without the metal current collector as claimed in claim 1, wherein the carbon fiber surface is treated by a plasma cleaning machine. The method can remove organic impurities on the surface of the carbon fiber, and can form a pseudo diffusion layer on the surface of the carbon fiber so as to improve the binding force between the carbon fiber and other substances.

3. The electrochemical energy storage electrode plate without the metal current collector as claimed in claim 1, wherein the surface treatment of the carbon nanotubes is achieved by steam of concentrated nitric acid using a hydrothermal method. The method can ensure the efficient and safe surface treatment of the carbon nano tube, and functional groups such as-COOH, -C ═ C-, -C-OH, -C-H and the like are added on the surface of the carbon nano tube, so that the surface hydrophilicity of the carbon nano tube is greatly improved.

4. The electrochemical energy storage electrode plate without the metal current collector as claimed in claim 1, wherein the ratio of carbon fiber, carbon nanotube and activated carbon is controlled. The carbon fibers in the three ensure the high strength and modulus of the current collector, ensure the formation of electrode plates and participate in the construction of a conductive network; the carbon nano tube has a lamellar structure similar to one-dimensional nano material graphite and has good conductivity, and a conductive network is constructed together with the carbon fiber, so that the internal resistance of the current collector is greatly reduced; the activated carbon with higher specific surface area is a high-quality electrode material of the super capacitor.

Technical Field

Porous activated carbon is used to make electrodes for supercapacitors by virtue of its high specific surface area. However, the activated carbon has poor conductivity and needs to be attached to an aluminum foil current collector. The invention relates to a method for integrating current collector electrodes, belonging to the field of electrochemical energy storage. The prepared electrode plate can be used for a traditional super capacitor, and can also be used for a zinc ion super capacitor or a battery. Furthermore, the carbon material in the pole piece is modified with an electrode material with redox activity on the surface, and then the electrode material can be used for an aqueous rechargeable battery.

Background

Supercapacitors are a new type of energy storage element that has emerged in recent years with an energy density intermediate between electrolytic capacitors and rechargeable batteries. The supercapacitor electrode based on porous activated carbon stores electric energy by physical adsorption of ions in electrolyte on the surface of the electrode, and belongs to double-electric-layer capacitance. One significant disadvantage is the low energy density, but high power density. The super capacitor has the advantages of safety, reliability, high charging and discharging speed, long cycle life, environmental protection and the like. Until now, super capacitors have been successfully applied in the fields of national defense, aerospace, electronic products, power communication and the like, and the application of super capacitors is believed to be continuously expanded.

At present, the commonly used wound supercapacitor electrode generally uses an aluminum foil as a current collector, and a porous activated carbon electrode material is coated on the surface of the aluminum foil. The coating is also added with a carbon black conductive agent and a polymer binder. At present, the commercialized super capacitor belongs to an organic device, i.e. the electrode solution is an organic solvent. The aqueous supercapacitor uses an aqueous solution as an electrolytic solution, for example, a solution of dilute sulfuric acid, lithium sulfate, sodium sulfate, or the like. The electrodes of such devices may have a higher specific capacitance. Although the voltage window is narrow, with the development of the technology, the technology is expected to break through and be commercialized. In addition, pseudo-capacitance materials such as metal oxides, conductive polymers and the like can be introduced into the electrode of the water-based supercapacitor, so that the specific capacitance is further improved. Since the traditional aluminum foil current collector is easy to corrode in aqueous solution, it is imperative to find a current collector which is corrosion resistant. The conductive carbon fiber cloth has the characteristics of flexibility and high conductivity, is an ideal choice, but is expensive. The carbon cloth is formed by carbonizing pre-oxidized polyacrylonitrile fiber fabric or weaving carbon fibers, and the carbon cloth with good conductivity is mainly an imported product. Therefore, the preparation of the pole piece made of all-carbon material and integrating the current collector and the electrode has important significance.

Disclosure of Invention

The technical invention provides a current collector preparation scheme which is simple in preparation process, low in cost and convenient for repeated operation. According to the invention, the energy storage electrode plate which can be self-supported and has low resistance is prepared by mixing the porous activated carbon, the high-conductivity chopped carbon fibers and the carbon nanotubes and adding the adhesive, and no additional metal current collector is needed. The carbon fiber can improve the conductivity, toughness and strength of the self-supporting current collector, and is matched with the carbon nano tube to participate in constructing a conductive network. The porous activated carbon serving as a common electrode material of the super capacitor has the characteristics of large specific surface area, good conductivity, stable chemical property and the like. The prepared self-supporting electrode slice has adjustable thickness and large specific surface area, and can be used for constructing various electrochemical devices, such as a traditional double electric layer super capacitor, a zinc-carbon combined hybrid super capacitor, a zinc ion battery and the like.

An electrochemical energy storage electrode plate without a metal current collector comprises the following preparation steps:

(1) The surface of the carbon fiber is treated with plasma. The experiment selects 3mm short carbon fiber, and the short carbon fiber is put into a plasma cleaning machine and treated for 180s in glow plasma of argon and oxygen mixed gas.

(2) And (5) surface treatment of the carbon nano tube. According to the matching proportion of 1g of carbon nano tube and 10mL of concentrated nitric acid (68 wt%), the concentrated nitric acid is poured into a polytetrafluoroethylene inner container, the carbon nano tube is added, the inner container is placed into a hydrothermal kettle, the hydrothermal kettle is heated to 150 ℃ and is kept warm for 5 hours, the inner container is taken out after being cooled to room temperature, and the inner container is washed with water and filtered until the pH value of the filtrate is neutral, so that the carbon nano tube after surface treatment is obtained. The infrared spectrum analysis is shown in FIG. 1, and the scanning electron microscope image is shown in FIG. 2 (a).

(3) And (4) mixing. Taking a proper amount of carbon fibers, ultrasonically dispersing the carbon fibers in ethanol for 1 hour, ultrasonically mixing the carbon fibers, the carbon nanotubes and the activated carbon in the ethanol according to the mass ratio of 1:2:2, then adding 5% of a binder (PTFE emulsion), and further ultrasonically mixing.

(4) and (6) tabletting. And filtering the mixture to obtain a filter cake, and transferring the filter cake to a 70 ℃ oven for drying. The dried filter cake is firstly pressed into a sheet with the thickness of 2mm by a tablet press, and then is rolled into a compact sheet with the thickness of 0.5mm by a roller press. The scanning electron micrograph thereof is shown in FIG. 2 (b).

(5) The obtained sheet was cut into electrode pieces of regular shapes, and immersed in a 1M aqueous solution of sulfuric acid. After several hours, the material is taken out and used as an electrode of the super capacitor to carry out an electrochemical energy storage performance test, and the result is shown in figure 3. The conductivity of the electrode sheet was analyzed as shown in fig. 4.

Compared with the prior art, the invention has the following remarkable advantages:

(1) The electrode plate prepared by the invention has good electric conduction and high specific surface area, and does not need a metal substrate as a current collector. The corrosion resistance is particularly suitable for aqueous electrolytes.

(2) The raw materials are common carbon materials, and the preparation process is simple and easy to operate; the prepared electrode plate has high specific capacity, and can be independently used for a water system super capacitor or used as a carrier for depositing pseudo-capacitance electrode materials on the surface of the electrode plate.

(3) The processing method is simple and suitable for expanded production. The thickness of the electrode plate current collector can be adjusted according to requirements from several micrometers to several millimeters.

Drawings

FIG. 1 is an infrared spectrum of carbon nanotubes before and after nitric acid treatment.

FIG. 2 is a scanning electron micrograph. (a) Scanning electron microscope images of carbon nanotube nitration treatment; (b) roll forming the carbon material bond map.

FIG. 3 is a test of electrochemical performance of a current collector and electrode integrated supercapacitor.

FIG. 4 is a graph of resistance versus time at a test frequency of 0.2s each time.

Detailed Description

The present invention is further illustrated by the following examples, but is not limited to the specific embodiments.

(1) And (3) drying 0.5g of 3mm short carbon fiber in a 70 ℃ oven, and performing plasma treatment on the carbon fiber for 180 seconds in an argon and oxygen mixed gas atmosphere by using a plasma cleaning machine for later use.

(2) Taking 1g of multi-wall carbon nano-tube with the diameter of 10-20 nm and 10mL of concentrated nitric acid with the mass concentration of 68 wt%, putting the multi-wall carbon nano-tube and the concentrated nitric acid into an inner container made of polytetrafluoroethylene materials, putting the inner container into a hydrothermal kettle, heating the inner container to 150 ℃, preserving heat for 5 hours, cooling the inner container to room temperature, taking the inner container out, and obtaining the carbon nano-tube after surface treatment for later use.

(3) And (2) placing 0.5g of carbon fiber subjected to surface treatment by the plasma in a beaker filled with 200mL of absolute ethyl alcohol for ultrasonic dispersion for 1h, after complete dispersion, adding 1g of carbon nanotube subjected to surface treatment, 1g of activated carbon and 0.4g of PTFE emulsion with the concentration of 60 wt% into the beaker together, and performing ultrasonic dispersion for 3h to obtain a uniformly dispersed mixture.

(4) Filtering the mixture obtained in the step (3), drying the obtained filter cake in a 70 ℃ oven, and then roughly pressing the filter cake into a sheet with the thickness of 2mm by using a tablet press, and rolling the sheet into a compact sheet with the thickness of 0.5mm by using a rolling machine.

(5) The sheet with a thickness of 0.5mm was cut into 1.5cm by 1.5cm square electrode pieces and immersed in 1M aqueous H2SO4 solution. And taking out after soaking for 2h, taking the membrane as a working electrode, taking a platinum sheet as a counter electrode, and forming a three-electrode system by using an Ag/AgCl reference electrode to perform electrochemical test.

the above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by the present specification, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.