Three-dimensional self-supporting composite structure electrode, preparation method thereof and lithium-air battery
阅读说明：本技术 三维自支撑的复合结构电极及其制备方法、锂空气电池 (Three-dimensional self-supporting composite structure electrode, preparation method thereof and lithium-air battery ) 是由 魏文飞 孔雪 曾梦丝 邹十美 谷建行 于 2019-11-15 设计创作，主要内容包括：本发明公开了三维自支撑的复合结构电极及其制备方法、锂空气电池。其中,所述三维自支撑的复合结构电极的制备方法为：先对聚氨酯海绵材料剪裁成所需的形状,再碳化处理；将碳化的聚氨酯海绵浸入氧化石墨烯溶液中,取出干燥；将该干燥后的材料浸泡于催化剂溶液,取出晾干,低温还原就得到了三维自支撑的复合结构电极。该复合结构电极以碳化聚氨酯海绵的纤维为骨架,用作整体的导电网络,在该碳化聚氨酯海绵纤维的外表及空隙处包裹、填充还原氧化石墨烯和催化剂,以增加该电极的导电性及比表面积,为反应提供大量的活性位点。该电极不含粘结剂,可有效防止电池充放电过程中副反应的发生,从而提高电池的能量密度。(The invention discloses a three-dimensional self-supporting composite structure electrode, a preparation method thereof and a lithium-air battery. The preparation method of the three-dimensional self-supporting composite structure electrode comprises the following steps: firstly, cutting a polyurethane sponge material into a required shape, and then carbonizing; immersing the carbonized polyurethane sponge into a graphene oxide solution, taking out and drying; and soaking the dried material in a catalyst solution, taking out and airing, and reducing at low temperature to obtain the three-dimensional self-supporting composite structure electrode. The composite structure electrode takes fibers of carbonized polyurethane sponge as a framework and is used as an integral conductive network, and reduced graphene oxide and a catalyst are wrapped and filled on the outer surface and the gaps of the carbonized polyurethane sponge fibers so as to increase the conductivity and the specific surface area of the electrode and provide a large number of active sites for reaction. The electrode does not contain a binder, and can effectively prevent side reactions from occurring in the charging and discharging processes of the battery, thereby improving the energy density of the battery.)
1. A preparation method of a three-dimensional self-supporting composite structure electrode comprises the following steps:
step 1: firstly, cutting a polyurethane sponge material into a required shape, and then carrying out carbonization treatment;
step 2: immersing the carbonized polyurethane sponge into a graphene oxide solution, taking out and drying;
and step 3: and soaking the dried material in a catalyst solution, taking out the material, airing the material at room temperature, and reducing the material at low temperature to obtain the three-dimensional self-supporting composite structure electrode.
2. The preparation method of claim 1, wherein the polyurethane sponge is cut into a column, and then ultrasonically cleaned with deionized water and absolute ethyl alcohol, and dried.
3. The method according to claim 1, wherein the carbonization treatment is carried out at 600 ~ 900 ℃ for 2.0 ~ 4.0.0 h in Ar or N atmosphere2。
4. The preparation method according to claim 1, wherein the concentration of the graphene oxide solution is 1 ~ 5mg/ml, the graphene oxide solution is uniformly dispersed by ultrasonic waves and used for soaking the carbonized polyurethane sponge, and the carbonized polyurethane sponge is taken out and dried.
5. The method of claim 1 wherein the catalyst solution is a chloride solution having a concentration of 0.45 ~ 0.55.55M.
6. The method of claim 5, wherein the chloride in the chloride solution is a chloride of one of Ru, Co, Pt, or Fe.
7. The preparation method of claim 1, wherein the low-temperature reduction is carried out at 190 ~ 210 ℃ for 3.5 ~ 4.5.5H in Ar/H atmosphere2Atmosphere in which H25 ~ 10%.
8. A three-dimensional self-supporting composite structure electrode prepared by the preparation method according to any one of claims 1 to 7, comprising a carbonized skeleton, reduced graphene oxide wrapped and filled in the outer surface and voids of the carbon skeleton, and a catalyst material.
9. A lithium-air battery comprising the three-dimensional self-supporting composite structure electrode of claim 8.
Technical Field
The invention relates to the technical field of battery electrodes, in particular to a positive electrode used as a component of a lithium air battery and the like, a preparation method thereof and the lithium air battery with the positive electrode.
Background
With the development of science and technology, lithium air batteries have received attention from people. Because the lithium-air battery has high theoretical energy density and high specific capacity, compared with the common lithium-ion battery anode material, the lithium-air battery anode active material, namely oxygen, can be provided by the external environment, namely air, is environment-friendly and has low cost, thereby having great development and application prospects. Therefore, it is necessary to prepare a porous anode material with high catalytic performance. The negative electrode of the lithium-air battery is lithium metal, and the positive electrode is a porous carbon material containing a catalyst. The positive electrode and the negative electrode are separated by a diaphragm, and electrolyte is added to form a complete battery structure. The positive electrode serves as an air electrode, which mainly contributes to the energy density of the battery and directly affects the output voltage and output power of the battery. During discharge, lithium ions are transported from the negative electrode to the positive electrode of this structure through the electrolyte, and are combined with oxygen to form Li2O2Staying on the positive electrode. At the same time, the electron current is transferred from the negative electrode to the positive electrode of the battery through an external circuit.
In order to increase the integrity of the electrode and prevent the deterioration of the battery performance caused by the falling of the electrode during the cycling, a binder is generally added to the electrode, but the binder, which is an inactive material in the battery, not only reduces the energy density of the battery but also causes a series of unnecessary side reactions after the addition. If an electrode without a binder can be designed, the energy density of the battery can be improved, and the positive effect on the development of future batteries can be achieved. However, the traditional three-dimensional self-supporting electrode is made by a hydrothermal method, and high temperature and long-time energy consumption are needed; the material is prepared by a sol-gel method or a template method, and has the disadvantages of complicated process, time and labor consumption and high cost.
Therefore, how to overcome the defects of large energy consumption, low efficiency and high cost in the preparation of the conventional three-dimensional self-supporting electrode is an urgent problem to be solved in the industry.
Disclosure of Invention
The invention provides an energy-saving, environment-friendly, simple-to-manufacture and low-cost three-dimensional self-supporting composite structure electrode, a preparation method thereof and a lithium-air battery with the electrode, aiming at solving the problems of high energy consumption, low efficiency and high cost in the preparation of the conventional three-dimensional self-supporting electrode.
The invention provides a preparation method of a three-dimensional self-supporting composite structure electrode, which comprises the following steps:
step 1: firstly, cutting a polyurethane sponge material into a required shape, and then carrying out carbonization treatment;
step 2: immersing the carbonized polyurethane sponge into a graphene oxide solution, taking out and drying;
and step 3: and soaking the dried material in a catalyst solution, taking out the material, airing the material at room temperature, and reducing the material at low temperature to obtain the three-dimensional self-supporting composite structure electrode.
Preferably, the polyurethane sponge is cut into a columnar body, and then ultrasonic cleaning and drying are respectively carried out by using deionized water and absolute ethyl alcohol.
Preferably, the carbonization temperature of the carbonization treatment is 600 ~ 900 ℃, the time is 2.0 ~ 4.0.0 h, and the atmosphere is Ar or N2。
Preferably, the concentration of the graphene oxide solution is 1 ~ 5mg/ml, the graphene oxide solution is uniformly dispersed by ultrasonic and then used for soaking the carbonized polyurethane sponge, and the carbonized polyurethane sponge is taken out and then subjected to vacuum freeze drying.
Preferably, the catalyst solution is a chloride solution, and the concentration is 0.45 ~ 0.55.55M.
Preferably, the chloride in the chloride solution is one of Ru, Co, Pt or Fe.
Preferably, the temperature of the low-temperature reduction is 190 ~ 210 ℃, the time is 3.5 ~ 4.5.5H, and the atmosphere is Ar/H2Atmosphere in which
The invention also provides a three-dimensional self-supporting composite structure electrode prepared by the preparation method, which comprises a carbonized framework, reduced graphene oxide and a catalyst material, wherein the reduced graphene oxide and the catalyst material are wrapped and filled on the surface and in gaps of the carbonized framework.
The invention further provides a lithium air battery comprising a three-dimensional self-supporting composite structure electrode of the invention.
The three-dimensional self-supporting composite structure electrode provided by the invention takes carbonized polyurethane sponge as a framework, so that an integral conductive network is provided, and simultaneously, reduced graphene oxide and a catalyst are wrapped and filled on polyurethane sponge fibers and gaps, so that the conductivity and the specific surface area of the electrode are increased, and a large number of active sites are provided for reaction. The electrode does not contain a binder, and can effectively prevent side reactions from occurring in the charging and discharging processes of the battery, thereby improving the energy density and the cycle performance of the battery. Compared with the prior art, the invention has the advantages of energy saving, environmental protection, simple manufacture and low cost.
Drawings
FIG. 1 is a schematic block diagram of a process for preparing a composite structured electrode according to the present invention;
wherein, PU: a polyurethane sponge; a CPU: carbonizing a polyurethane sponge; GO: graphene oxide;
rGO: reducing graphene oxide; CPU/GO is a carbonized polyurethane sponge/graphene oxide composite material;
CPU/rGO/M carbonized polyurethane sponge/reduced graphene oxide/metal catalyst (Ru, Pt, Fe, etc.) composite material
FIG. 2 is a schematic cross-sectional view of a composite structured electrode of the present invention;
FIG. 3 is a scanning electron micrograph of an electrode of the composite structure of the present invention;
fig. 4 is a charge-discharge curve diagram of the composite-structure electrode of the present invention applied to a lithium-air battery.
Detailed Description
Fig. 1 is a block flow diagram of a method for manufacturing a three-dimensional self-supporting composite structure electrode according to the present invention. The preparation method comprises the following steps:
1. cutting polyurethane sponge into required shape, such as column, in this example, cutting into cylinder with height of 1cm and diameter of 1cm, and ultrasonic cleaning the cut material with deionized water and anhydrous ethanol respectivelyDrying for several times; carbonizing at 750 deg.C for 2.5h in Ar or N atmosphere2And the like. The carbonization temperature can be selected as required: 600 ℃, 650 ℃, 700 ℃, 800 ℃, 850 ℃, 900 ℃ for 2h, 3h, 3.5h and 4 h. As the carbonization temperature increases and the time increases, the electrode becomes more brittle and the deeper the carbonization, the more conductive.
2. The method comprises the steps of preparing a graphene oxide solution with the concentration of 2.5mg/ml, uniformly dispersing by ultrasonic, immersing carbonized polyurethane sponge into the graphene oxide solution, taking out the graphene oxide solution, and drying to obtain the carbonized polyurethane sponge/graphene oxide composite material, wherein the concentration of the graphene oxide solution can be selected to be 1 ~ 5mg/ml as required, the higher the mass of an electrode is along with the increase of the concentration, the stronger the electrical conductivity is, the added reduced graphene oxide is wrapped on carbonized polyurethane sponge fibers and filled in gaps of the sponge fibers, on one hand, the reduced graphene oxide is used as a conductive framework to increase the electrical conductivity of the electrode, on the other hand, the reduced graphene oxide can be used as a porous carbon material to provide a space for reaction on the electrode, oxygen is supplied to pass through the porous carbon material, and a proper catalytic action is provided.
3. Preparing a catalyst solution, namely selecting a ruthenium chloride solution, wherein the concentration is 0.5M; soaking the dried composite material in the catalyst solution, taking out, drying at room temperature, reducing at 200 deg.C for 4 hr in Ar/
Fig. 2 and fig. 3 are schematic diagrams of embodiments of the three-dimensional self-supporting composite structure electrode prepared by the preparation method of the present invention. The three-dimensional self-supporting composite structure electrode is cut into a cylinder shape and comprises a carbonized framework, reduced graphene oxide and a catalyst material, wherein the reduced graphene oxide and the catalyst material are wrapped and filled on the outer surface of the carbon framework and in gaps. As shown in fig. 2, the carbonized skeleton is a spring-like carbonized polyurethane sponge fiber, the reduced graphene oxide material is a material wrapped on the fiber and filled in the fiber gap, and the catalyst material is distributed on the reduced graphene oxide.
The three-dimensional self-supporting composite structure electrode prepared by the method is directly used in a lithium air battery or a super capacitor.
As shown in FIG. 4, the lithium-air battery having the electrode of the three-dimensional self-supporting composite structure of the present invention was subjected to battery performance tests at a current density of 0.1mA/cm, respectively2、0.5mA/cm2The specific capacity of the battery reaches 2.7 mAh/cm respectively after charge and discharge tests2、4.9 mAh/cm2. Namely: the electrode has high-efficiency catalytic effect and the specific capacity of the battery is high.
The three-dimensional self-supporting composite structure electrode provided by the invention takes carbonized polyurethane sponge fiber as a framework, so that an integral conductive network is provided, and simultaneously, the polyurethane sponge fiber and gaps are coated and filled with a reduced graphene oxide catalyst, so that the conductivity and the specific surface area of the electrode are increased, and a large number of active sites are provided for reaction. The electrode does not contain a binder, and can effectively prevent side reactions from occurring in the charging and discharging processes of the battery, thereby improving the energy density and the cycle performance of the battery. Compared with the prior art, the invention has the advantages of energy saving, environmental protection, simple manufacture and low cost.
The foregoing is considered as illustrative only of the embodiments of the invention. It should be understood that any modifications, equivalents and changes made within the spirit and framework of the inventive concept are intended to be included within the scope of the present invention.
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