A soluble copper-based composite material and its preparation method and application

Abstract

The present invention discloses a soluble copper-based composite material, which is a sheet material with a thickness of 4 to 10 μm and is composed of 60 to 90 wt% of copper powder, 8 to 38 wt% of a binder and 2 to 5 wt% of a conductive agent; the binder is sodium alginate, the copper powder is composed of two different copper powders with particle sizes of 0.2 μm and 1.1 μm respectively in a weight ratio of 1 to 5:1, and the conductive agent is one or more of carbon nanotubes, carbon black and graphene; the preparation method and application of the composite material are also disclosed; the composite material of the present invention is intended to replace traditional copper foil, and its water-soluble property enables complete self-destruction of electrical devices in an aqueous environment, greatly improving the safety of the equipment. The composite material of the present invention has excellent bonding performance with electrode materials and a large contact area, thereby effectively improving the effective capacity of lithium batteries.

Description

Technical Field

[0001] The patent of this invention belongs to the field of electrochemical energy storage, and specifically relates to a soluble copper-based composite material, as well as its preparation method and a current collector for the negative electrode of a lithium battery. Background Art

[0002] With growing environmental awareness, circular, renewable energy has become a core industry that countries around the world are competing to develop. In recent years, the market share of new energy lithium-ion battery vehicles has steadily climbed. Simultaneously, wind and solar power plants have increasingly relied on lithium-ion battery energy storage technology, undoubtedly driving strong demand for lithium-ion battery energy storage technology. As an essential component of new energy lithium-ion batteries, market demand for negative electrode current collector copper foil has also rapidly increased, becoming a key force driving the sustainable development of the new energy industry.

[0003] Currently, copper foil is the main material for negative electrode current collectors, but there are some problems with the existing copper foil as a negative electrode current collector. Although copper is an excellent metal conductor with electrical conductivity second only to silver, and it is abundant in resources, cheap and easy to obtain, under some special processes, such as the production of rolled copper foil, its manufacturing cost is relatively high. The price of pure copper is 2 to 3 times that of pure aluminum. In addition, due to the difference in the surface properties of the copper foil and the surface of the negative electrode material, usually, there are certain problems with the bonding strength between the negative electrode binder and the copper foil surface, and the negative electrode material is easier to peel off. Thirdly, in some special fields, lithium batteries are used as endurance power, but in order to protect the secrets of special equipment, the lithium batteries of the characteristic equipment need to adopt a self-destruction program. Copper foil is usually difficult to self-destruct. Therefore, the information of the special equipment is inferred through analysis of the lithium battery, which creates the risk of leakage. Summary of the Invention

[0004] Based on the above problems, namely, the high preparation cost of existing copper foil and certain problems with the contact area and adhesion with the negative electrode material, and the problem that the existing copper foil is not easy to self-destruct, resulting in easy leakage, one of the purposes of the present invention is to provide a soluble copper-based composite material. The copper-based composite material provided by the present invention can be used as a current collector material to replace copper foil. The copper-based composite material is easily dissolved in water. In an aqueous environment, the copper foil can be completely dissolved and the electrical device can be completely self-destructed; in addition, the copper-based composite material of the present invention can be well bonded to the electrode material, which can effectively improve the bonding strength between the negative electrode material and the copper-based composite material, and can achieve green recycling of copper foil without using organic solvents for recycling.

[0005] The present invention solves the technical problem by adopting a technical solution: a soluble copper-based composite material, a sheet material with a thickness of 4 to 10 μm, comprising, by weight, 60 to 90 wt% copper powder, 8 to 38 wt% binder, and 2 to 5 wt% conductive agent. The binder is sodium alginate, and the copper powder is composed of two different copper powders with particle sizes of 0.2 μm and 1.1 μm, respectively, in a weight ratio of 1 to 5:1. Different particle size gradations ensure the density of the composite material, further improve adhesion and conductivity, and the conductive agent is one or more of carbon nanotubes, carbon black, and graphene. Within a certain range, the ratio of the copper powder, binder, and conductive agent can achieve conductivity equivalent to or slightly better than that of copper foil.

[0006] Furthermore, the conductive agent is a mixture of graphene and carbon black in a weight ratio of 1:2-5, or a mixture of carbon nanotubes and carbon black in a weight ratio of 1:2-5. Graphene is a flaky material, carbon black is granular, and carbon nanotubes are tubular. The combination of granular, flaky, and tubular structures can enhance conductivity and improve the strength of the composite material.

[0007] Furthermore, the copper powder content is 80wt%, the binder content is 17wt%, and the conductive agent content is 3wt%. The above proportions can ensure good electrical conductivity and good bonding strength between the obtained copper-based composite material and the negative electrode material.

[0008] A second object of the present invention is to provide a method for preparing a soluble copper-based composite material, comprising the following steps:

[0009] (1) Weighing 40-80 wt% of copper powder with a particle size of 0.2 μm, 16-40 wt% of copper powder with a particle size of 1.1 μm, 3 wt% of a conductive agent, and 17 wt% of sodium alginate in a certain proportion, wherein the particle size of the conductive agent is 0.05-0.5 μm, and vibrating and mixing the materials in a ball mill mixing tube to uniformly mix the materials to obtain a mixed powder;

[0010] (2) Add an appropriate amount of ultrapure water to the mixed powder and vibrate and grind again until a slurry with appropriate consistency is formed. The viscosity of the slurry is controlled at 1300-1600 mPa.s; appropriate viscosity is conducive to coating and molding.

[0011] (3) Use glass as the substrate, ensure that the substrate surface is flat and clean, and use a coating scraper to evenly apply the prepared slurry on the glass substrate; place the coated glass in a vacuum oven at 50-90°C and dry for 2-10 hours to ensure that the slurry is completely solidified; the vacuum drying temperature is 60°C and the drying time is 8 hours.

[0012] (4) The dried copper-based composite material is rolled and peeled to control the thickness and cut as needed to obtain a soluble copper-based composite material of the required length and width.

[0013] A third object of the present invention is to provide the above-mentioned soluble copper-based composite material for a current collector of a negative electrode of a lithium battery.

[0014] A fourth object of the present invention is to provide a lithium battery using the above-mentioned current collector.

[0015] The beneficial technical effects obtained by the present invention are as follows:

[0016] The copper-based composite material provided by the present invention exhibits excellent solubility in a water environment and is therefore particularly suitable for use as a key component of lithium batteries in marine special equipment. In specific application scenarios, especially when special equipment faces potential risks of confidentiality disclosure, the lithium battery can achieve self-destruction through a complete water-dissolution mechanism, thereby ensuring the absolute security of sensitive information. This technological breakthrough not only broadens the application field of copper-based composite materials, but also provides a strong technical guarantee for the safety of marine special equipment. Through precise preparation technology and a unique dissolution mechanism, the present invention ensures that lithium batteries can dissolve quickly and thoroughly under extreme conditions, avoiding possible risks of information leakage and environmental pollution.

[0017] The copper-based composite material provided by the present invention can have good bonding force and bonding strength with the negative electrode material. The copper-based composite material of the present invention is made of copper powder and conductive agent powder precisely bonded by a specific binder, while the negative electrode material is formed by the powder additives such as negative electrode active material powder and conductive agent also precisely bonded by a binder. During the hot pressing process of the lithium battery slurry, the powder particles of the two materials can be compatible with each other and in close contact, effectively increasing the contact area. This design not only enhances the bonding strength between the copper-based composite material and the negative electrode material, but also effectively reduces the interface impedance between the copper foil and the negative electrode material, significantly improving the overall performance of the lithium battery.

[0018] By precisely controlling the particle size ratio of copper powder to conductive agent powder, this invention significantly improves the conductivity of the copper-based composite material, achieving a level of conductivity comparable to that of copper foil current collectors. Furthermore, the copper-based composite material exhibits excellent water solubility, providing unique advantages for specific applications.

[0019] The present invention adds a conductive agent and an appropriate amount of binder to copper powder as a composition, so the copper material used is reduced compared with pure copper foil, and the preparation method is relatively simple and the preparation cost is relatively low. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the embodiments.

[0021] Additional aspects and advantages of the present invention will be described in part in the following description, and in part will become apparent from the following description or learned through practice of the present invention. It should be understood that the following description is only used to explain the present invention and is not intended to limit the present invention.

[0022] Unless otherwise specified, the raw materials and equipment used in the present invention can be purchased from the market or are commonly used in the art. The methods in the embodiments, unless otherwise specified, are all conventional methods in the art.

[0023] The following further describes the method in conjunction with specific implementation methods. Example 1

[0024] The present embodiment discloses a soluble copper-based composite material, and the preparation steps are as follows: weighing 40wt% copper powder with a particle size of 0.2μm, 40wt% copper powder with a particle size of 1.1μm, 1wt% graphene, 2wt% carbon black and 17wt% sodium alginate, where the particle size of the graphene and carbon black is 0.05-0.5μm, vibrating and grinding the materials in a ball mill mixing tube to uniformly mix the materials to obtain a mixed powder; adding an appropriate amount of ultrapure water to the mixed powder, vibrating and grinding again until the viscosity of the formed slurry is 1400mPa.s; using glass as a substrate, ensuring that the substrate surface is flat and clean, and using a coating scraper to evenly apply the prepared slurry on the substrate; placing the coated glass in a vacuum oven at 60°C and drying for 8 hours to ensure that the slurry is completely cured and tightly bonded to the glass substrate; rolling the dried glass to control the thickness of the copper-based composite material, peeling, and cutting as needed to obtain a soluble copper-based composite material of the required length and width. The conductive agent powder and copper powder achieve multi-level particle size grading, thereby increasing the density of the copper-based composite material and improving the conductive performance.

[0025] Resistivity Test: The copper-based composite material from Example 1 was subjected to a copper foil resistivity test using the four-wire method to evaluate the conductive properties of the current collector. Use wires to connect the copper-based composite material sample to a four-wire resistance meter. Ensure a secure connection and good contact. The four-wire method requires two pairs of wires: one pair for transmitting current (current wires) and the other pair for measuring voltage (voltage wires). Set appropriate test parameters, such as current level and test time, based on the dimensions (length, cross-sectional area) of the copper-based composite material sample and the expected resistivity range. Turn on the power and start the four-wire resistance meter. Follow the instrument's operating instructions to begin the test. The instrument will automatically transmit current to the copper-based composite material sample and measure voltage. After the test, the instrument will display the resistance value of the copper-based composite material sample. Record this value for subsequent calculations. Calculate the resistivity ρ: ρ = R * S / L, where R is the measured resistance value, S is the cross-sectional area of ​​the copper-based composite material sample, and L is the length of the copper-based composite material sample.

[0026] Water solubility test of copper-based composite materials: The prepared copper-based composite materials are used as test samples, and the prepared copper-based composite materials are placed in a certain volume of aqueous solution. The aqueous solution is kept magnetically stirred, and after 10 minutes, the copper-based composite materials are observed to see whether they are completely dissolved, partially dissolved, or not dissolved. Complete dissolution means that there are no block or flaky materials, and the dissolved materials in the aqueous solution are evenly dispersed; partial dissolution means that there are fragmented block materials in the solution; insolubility means that the negative electrode slurry on the copper-based composite material sheet is not dissolved. For the convenience of recording, complete dissolution is marked as 3, partial dissolution is marked as 2, and insolubility is marked as 1. The data of the specific embodiment are shown in the table below. Example 2

[0027] The present embodiment discloses a soluble copper-based composite material, and the preparation steps are as follows: weighing 60wt% copper powder with a particle size of 0.2μm, 20wt% copper powder with a particle size of 1.1μm, 1wt% graphene, 2wt% carbon black and 17wt% sodium alginate, where the particle size of the graphene and carbon black is 0.05-0.5μm, vibrating and grinding the materials in a ball mill mixing tube to uniformly mix the materials to obtain a mixed powder; adding an appropriate amount of ultrapure water to the mixed powder, vibrating and grinding again until the viscosity of the formed slurry is 1300mPa.s; using glass as a substrate, ensuring that the substrate surface is flat and clean, and using a coating scraper to evenly apply the prepared slurry on the substrate; placing the coated glass in a vacuum oven at 50°C and drying for 10 hours to ensure that the slurry is completely cured and tightly bonded to the glass substrate; rolling the dried glass to control the thickness of the copper-based composite material, peeling, and cutting as needed to obtain a soluble copper-based composite material of the required length and width. Example 3

[0028] The present embodiment discloses a soluble copper-based composite material, and the preparation steps are as follows: weighing 70wt% copper powder with a particle size of 0.2μm, 14wt% copper powder with a particle size of 1.1μm, 1wt% graphene, 2wt% carbon black and 17wt% sodium alginate, where the particle size of the graphene and carbon black is 0.05-0.5μm, vibrating and grinding the materials in a ball mill mixing tube to uniformly mix the materials to obtain a mixed powder; adding an appropriate amount of ultrapure water to the mixed powder, vibrating and grinding again until the viscosity of the formed slurry is 1500mPa.s; selecting glass as a substrate, ensuring that the substrate surface is flat and clean, and using a coating scraper to evenly apply the prepared slurry on the substrate; placing the coated glass in a vacuum oven at 60°C and drying for 8 hours to ensure that the slurry is completely cured and tightly bonded to the glass substrate; rolling the dried glass to control the thickness of the copper-based composite material, peeling, and cutting as needed to obtain a soluble copper-based composite material of the required length and width. Example 4

[0029] The present embodiment discloses a soluble copper-based composite material, and the preparation steps are as follows: weighing 80wt% copper powder with a particle size of 0.2μm, 16wt% copper powder with a particle size of 1.1μm, 1wt% graphene, 2wt% carbon black and 17wt% sodium alginate, where the particle size of the graphene and carbon black is 0.05-0.5μm, vibrating and grinding the materials in a ball mill mixing tube to uniformly mix the materials to obtain a mixed powder; adding an appropriate amount of ultrapure water to the mixed powder, vibrating and grinding again until the viscosity of the formed slurry is 1600mPa.s; using glass as a substrate, ensuring that the substrate surface is flat and clean, and using a coating scraper to evenly apply the prepared slurry on the substrate; placing the coated glass in a vacuum oven at 80°C and drying for 9 hours to ensure that the slurry is completely cured and tightly bonded to the glass substrate; rolling the dried glass to control the thickness of the copper-based composite material, peeling, and cutting as needed to obtain a soluble copper-based composite material of the required length and width. Example 5

[0030] The present embodiment discloses a soluble copper-based composite material, and the preparation steps are as follows: weighing 80wt% copper powder with a particle size of 1.1μm, 40wt% copper powder with a particle size of 1.1μm, 1wt% graphene, 2wt% carbon black and 17wt% sodium alginate, where the particle size of the graphene and carbon black is 0.05-0.5μm, vibrating and grinding the materials in a ball mill mixing tube to uniformly mix the materials to obtain a mixed powder; adding an appropriate amount of ultrapure water to the mixed powder, vibrating and grinding again until the viscosity of the formed slurry is 1400mPa.s; using glass as a substrate, ensuring that the substrate surface is flat and clean, and using a coating scraper to evenly apply the prepared slurry on the substrate; placing the coated glass in a vacuum oven at 60°C and drying for 8 hours to ensure that the slurry is completely cured and tightly bonded to the glass substrate; rolling the dried glass to control the thickness of the copper-based composite material, peeling, and cutting as needed to obtain a soluble copper-based composite material of the required length and width. Example 6

[0031] The present embodiment discloses a soluble copper-based composite material, and the preparation steps are as follows: weighing 60wt% copper powder with a particle size of 0.2μm, 20wt% copper powder with a particle size of 1.1μm, 1wt% carbon nanotubes, 2wt% carbon black and 17wt% sodium alginate, where the particle size of the carbon nanotubes and carbon black is 0.05-0.5μm, vibrating and grinding the materials in a ball mill mixing tube to uniformly mix the materials to obtain a mixed powder; adding an appropriate amount of ultrapure water to the mixed powder, and vibrating and grinding again until the viscosity of the formed slurry is 1400mPa.s; using glass as a substrate, ensuring that the substrate surface is flat and clean, and using a coating scraper to evenly apply the prepared slurry on the substrate; placing the coated glass in a vacuum oven at 60°C and drying for 8 hours to ensure that the slurry is completely cured and tightly bonded to the glass substrate; rolling the dried glass to control the thickness of the copper-based composite material, peeling, and cutting as needed to obtain a soluble copper-based composite material of the required length and width. Example 7

[0032] The present embodiment discloses a soluble copper-based composite material, and the preparation steps are as follows: weighing 60wt% copper powder with a particle size of 0.2μm, 20wt% copper powder with a particle size of 1.1μm, 3wt% carbon black and 17wt% sodium alginate, wherein the particle size of the carbon black is 0.05-0.5μm, vibrating and grinding the materials in a ball mill mixing tube to uniformly mix the materials to obtain a mixed powder; adding an appropriate amount of ultrapure water to the mixed powder, vibrating and grinding again until the viscosity of the formed slurry is 1400mPa.s; using glass as a substrate, ensuring that the substrate surface is flat and clean, and using a coating scraper to evenly apply the prepared slurry on the substrate; placing the coated glass in a vacuum oven at 60°C and drying for 8 hours to ensure that the slurry is completely cured and tightly bonded to the glass substrate; rolling the dried glass to control the thickness of the copper-based composite material, peeling, and cutting as needed to obtain a soluble copper-based composite material of the required length and width.

[0033] Comparative Example 1: Weigh 55wt% copper powder with a particle size of 0.2μm, 2wt% graphene, 3wt% carbon black and 40wt% sodium alginate, where the particle size of graphene and carbon black is 0.05-0.5μm, and vibrate and grind them in a ball mill mixing tube to uniformly mix these materials to obtain a mixed powder; add an appropriate amount of ultrapure water to the mixed powder, and vibrate and grind them again until the viscosity of the formed slurry is 1400mPa.s; use glass as a substrate, ensure that the surface of the substrate is flat and clean, and use a coating scraper to evenly apply the prepared slurry on the substrate; place the coated glass in a vacuum oven at 60°C and dry it for 8 hours to ensure that the slurry is completely cured and tightly bonded to the glass substrate; roll the dried glass to control the thickness of the copper-based composite material, peel it, and cut it as needed to obtain a soluble copper-based composite material of the required length and width.

[0034] Comparative Example 2: Weigh 90wt% of copper powder with a particle size of 0.2μm, 5wt% of carbon black and 17wt% of sodium alginate, and the particle size of graphene and carbon black is 0.05-0.5μm, and vibrate and grind them in a ball mill mixing tube to uniformly mix these materials to obtain a mixed powder; add an appropriate amount of ultrapure water to the mixed powder, and vibrate and grind them again until the viscosity of the formed slurry is 1400mPa.s; use glass as a substrate, ensure that the surface of the substrate is flat and clean, and use a coating scraper to evenly apply the prepared slurry on the substrate; place the coated glass in a vacuum oven at 60°C and dry it for 8 hours to ensure that the slurry is completely cured and tightly bonded to the glass substrate; roll the dried glass to control the thickness of the copper-based composite material, peel it, and cut it as needed to obtain a soluble copper-based composite material of the required length and width.

[0035] Comparative Example 3: Pure copper foil of the same size as in Example 1 was used for testing.

[0036] The physical properties of the embodiments and comparative examples are shown in the following table.

[0037] .

[0038] From the data in the above table, it can be seen that Examples 1 to 3 compare the effects of copper powders with different particle size gradations on the electrical conductivity. The copper powders with different particle size gradations have a significant effect on the electrical conductivity of the copper-based composite material.

[0039] Comparison of the data of Examples 4 to 5 shows that copper powders of different particle sizes have an important influence on the conductive properties as a composition. Comparison of the data of Examples 4 to 5 with the data of Examples 1 to 3 shows that different particle size gradations can improve the conductive properties.

[0040] The data of Example 6 is mainly compared with that of Example 2. The addition of different conductive agents will produce different conductive properties.

[0041] Comparing the data of Comparative Examples 1 to 2 with the data of Examples 1 to 5, it is found that different component ratios have an important influence on the conductive properties.

[0042] Compared with Examples 1 to 5 and Comparative Example 3, the conductivity of the copper-based composite material is slightly worse than that of copper foil, but it can achieve comparable conductivity and is soluble, which further expands the selection and development of current collectors and application scenarios.

[0043] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A soluble copper-based composite material, characterized in that: The invention relates to a sheet material with a thickness of 4 to 10 μm, which is composed of 60 to 90 wt% of copper powder, 8 to 38 wt% of a binder and 2 to 5 wt% of a conductive agent. The binder is sodium alginate, the copper powder is composed of two different copper powders with particle sizes of 0.2 μm and 1.1 μm respectively, in a weight ratio of 1 to 5:1, and the conductive agent is one or more of carbon nanotubes, carbon black and graphene.

2. A soluble copper-based composite material according to claim 1, characterized in that: The conductive agent is a mixture of graphene and carbon black in a weight ratio of 1:2-5, or a mixture of carbon nanotubes and carbon black in a weight ratio of 1:2-5.

3. A soluble copper-based composite material according to claim 2, characterized in that: The copper powder content is 80wt%, the binder content is 17wt%, and the conductive agent content is 3wt%.

4. A method for preparing a soluble copper-based composite material according to claim 1, characterized in that: Here are the steps: (1) Weigh copper powder, conductive agent and sodium alginate in proportion, vibrate and grind them in a ball mill mixing tube, and mix them evenly to obtain a mixed powder; (2) Add ultrapure water to the mixed powder and vibrate and grind again until a slurry with a viscosity of 1300-1600 mPa.s is formed; (3) Use glass as the substrate, ensure that the substrate surface is flat and clean, and use a coating scraper to evenly apply the prepared slurry on the glass substrate; place the coated glass in a vacuum oven at 50-90°C and dry for 2-10 hours to ensure that the slurry is completely cured; (4) The dried copper-based composite material is rolled, peeled, and cut to obtain a soluble copper-based composite material.

5. A soluble copper-based composite material as claimed in claim 1 used as a current collector for a negative electrode of a lithium battery.

6. A lithium battery, characterized in that: The current collector according to claim 5 is used.