A soluble solid battery negative electrode composite sheet and a preparation method and application thereof

Abstract

The application discloses a soluble solid-state battery negative composite pole piece which is composed of a copper-based composite current collector and a negative material active layer coated on the copper-based composite current collector; the copper-based composite current collector is a soluble copper-based composite material prepared from copper powder, sodium alginate and a conductive agent; and the negative material active layer comprises 70-90 parts of graphite, 4-12 parts of polyvinyl alcohol, 5-13 parts of Li7La3Zr2O 12 7 and 1-5 parts of carbon black; the polyvinyl alcohol is a medium molecular weight polyvinyl alcohol with a molecular weight of 120000-150000; and a preparation method and a battery are also disclosed; the composite pole piece not only has normal negative functions, but also can be assembled into a soluble solid-state battery with a solid-state electrolyte and a corresponding positive pole piece; moreover, the solubility design greatly simplifies the recycling process of the battery, is favorable for recycling and reuse of active substances, and provides a new solution for sustainable development of lithium batteries.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage, specifically relating to a soluble solid-state battery negative electrode composite sheet, its preparation method, and its application in lithium batteries. Background Technology

[0002] Against the backdrop of the global energy revolution, lithium batteries, due to their superior performance characteristics such as high energy density, long cycle life, and low self-discharge rate, have become indispensable energy storage devices in electronic products such as electric vehicles, smartphones, and drones. However, with the in-depth research and widespread application of lithium battery technology, positive and negative electrode materials face a series of challenges and problems.

[0003] Negative electrode current collectors play a crucial role in lithium-ion batteries, but their limitations are becoming increasingly apparent in certain applications. This is especially true in scenarios requiring high safety and rapid self-destruction capabilities, such as the military and specialized equipment sectors, where the properties of the negative electrode current collector are paramount.

[0004] However, commonly used negative electrode current collector materials (such as copper or other metal alloys) often have low solubility or high stability, which makes it difficult to achieve rapid and complete self-destruction of the battery when it is damaged or under certain conditions, thereby increasing the risk of information leakage or safety accidents. Summary of the Invention

[0005] To address the shortcomings of existing technologies, one objective of this invention is to provide a novel soluble solid-state battery negative electrode composite electrode. This electrode uses a soluble material as the negative electrode current collector and coats it with a negative electrode active layer. The resulting electrode not only possesses normal negative electrode functionality and can be assembled with a solid electrolyte and a corresponding positive electrode to form a soluble solid-state battery, but its soluble design also greatly simplifies the battery recycling process, facilitating the recovery and reuse of active materials and providing a new solution for the sustainable development of lithium batteries.

[0006] The technical solution adopted by this invention to solve its technical problem is: a soluble solid-state battery negative electrode composite electrode, comprising a copper-based composite current collector and a negative electrode material active layer coated on the copper-based composite current collector; the copper-based composite current collector is a soluble copper-based composite material prepared by copper powder, sodium alginate and a conductive agent; calculated by weight, the negative electrode material active layer contains 70-90 parts graphite, 4-12 parts polyvinyl alcohol, and a composite solid electrolyte Li7La3Zr2O. 125-13 parts of carbon black and 1-5 parts of polyvinyl alcohol; the polyvinyl alcohol is a medium molecular weight polyvinyl alcohol with a molecular weight of 120,000-150,000. Sodium alginate is used as a binder in the soluble copper-based composite material, which has good water solubility. The above-mentioned soluble copper-based composite material can be well compatible with the negative electrode active material, with good interfacial compatibility and a large contact area. Polyvinyl alcohol is used as a binder in the active layer of the negative electrode material, which can be well dissolved in aqueous solution. Moreover, polyvinyl alcohol and sodium alginate have similar polarity and can be well compatible, further improving compatibility.

[0007] Furthermore, the thickness of the copper-based composite current collector is 4–10 μm, and the content of each component, by weight percentage, includes 60–90 wt% copper powder, 8–38 wt% sodium alginate binder, and 2–5 wt% conductive agent. Preferably, the copper powder content is 80 wt%, the sodium alginate content is 17 wt%, and the conductive agent content is 3 wt%.

[0008] Furthermore, 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 1:1.

[0009] Furthermore, the conductive agent is a mixture of graphene and carbon black in a weight ratio of 1:2. Different particle size distributions can ensure the density of the composite material, further improving its adhesion and conductivity. Graphene is a sheet-like material, while carbon black is granular. The combination of granular and sheet-like structures can enhance conductivity and also improve the strength of the composite material.

[0010] Furthermore, the Li7La3Zr2O 12 Li7La3Zr2O was obtained by using LiOH•H2O as the lithium source, molding under pressure of 4MPa, and then sintering at 1000℃ for 15 h. 12 Ceramic shards.

[0011] Furthermore, the active layer of the negative electrode material comprises 80 parts graphite, 10 parts polyvinyl alcohol, and Li7La3Zr2O. 12 8 parts and 2 parts carbon black.

[0012] A second objective of this invention is to provide a method for preparing the above-mentioned solid-state battery negative electrode composite sheet, comprising the following steps:

[0013] Step 1: Weigh 80 parts copper powder, 1 part graphene, 2 parts carbon black and 17 parts sodium alginate, and vibrate and grind them in a ball mill mixing tube to make the materials uniformly mixed to obtain a mixed powder. Add ultrapure water and vibrate and grind again until a slurry A with a viscosity of 1300-1600 mpa.s is formed. Coat slurry A onto a glass substrate, dry it in a vacuum oven at 50-90°C for 2-10 hours, roll it, and peel it off to obtain a soluble copper-based composite material.

[0014] Step 2, weigh out 80 parts of graphite and 8 parts of Li7La3Zr2O 12 Mix 2 parts carbon black with dry powder, and mix all components evenly. Add a small amount of N-methylpyrrolidone and ball mill to obtain slurry B. Weigh 10 parts polyvinyl alcohol and add it to slurry B. Continue to ball mill at a rotation speed of 300-350 r / min and a revolution speed of 2-5 r / min for 2-6 h. Use a high-shear emulsifier for high-speed stirring to obtain negative electrode active slurry.

[0015] Step 3: Coat the prepared negative electrode active slurry onto the soluble copper-based composite material, dry it at 40-80°C, and roll the dried electrode sheet using a roller press to obtain the soluble solid-state battery negative electrode composite sheet.

[0016] The third objective of this invention is to provide the above-mentioned solid-state battery negative electrode composite sheet for use in lithium batteries.

[0017] The beneficial effects of this invention are:

[0018] This invention uses a soluble copper-based composite material as the current collector, and then coats it with a negative electrode active layer to prepare a fully soluble solid-state battery negative electrode composite sheet. It verifies for the first time that the composite sheet can achieve normal negative electrode function and can be assembled with a solid electrolyte and a corresponding positive electrode sheet to form a fully soluble solid-state battery. Furthermore, due to the fully soluble design, the battery is easy to recycle and facilitates the recovery of active materials.

[0019] The soluble solid-state battery negative electrode composite sheet provided by this invention further expands the special applications of lithium-ion batteries. In this invention, sodium alginate is used as a binder in the soluble copper-based composite material, which has good water solubility. Moreover, the above-mentioned soluble copper-based composite material can be well compatible with the negative electrode active material, with good interfacial compatibility and a large contact area. Polyvinyl alcohol is used as a binder in the active layer of the negative electrode material, which can be well dissolved in aqueous solution. Furthermore, polyvinyl alcohol and sodium alginate have similar polarity and can be well compatible, further improving compatibility. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the negative electrode composite electrode structure of the present invention.

[0021] The figures are labeled as follows: 1—Active layer of negative electrode material, 2—Copper-based composite current collector. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0023] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. It should be understood that the following description is merely illustrative and is not intended to limit the invention.

[0024] Unless otherwise specified, the raw materials and equipment used in this invention can be purchased from the market or are commonly used in the field. Unless otherwise specified, the methods in the embodiments are conventional methods in the field. Example 1

[0025] The method for preparing the composite negative electrode of a solid-state battery provided in this embodiment includes the following steps.

[0026] Weigh out 40 parts by weight of copper powder with a particle size of 0.2 μm, 40 parts by weight of copper powder with a particle size of 1.1 μm, 1 part by weight of graphene, 2 parts by weight of carbon black, and 17 parts by weight of sodium alginate. The particle sizes of graphene and carbon black are 0.05–0.5 μm. Vibrate and grind these materials in a ball mill mixing tube to obtain a mixed powder. Add an appropriate amount of ultrapure water to the mixed powder and vibrate and grind again until the viscosity of the resulting slurry is 1300–1600 mPa·s. Select glass as the substrate, ensuring that the substrate surface is flat and clean. Use a coating doctor blade to evenly coat the prepared slurry onto the 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 and tightly bonded to the glass substrate. Roll press the dried glass to control the thickness of the copper-based composite material to 5.5 μm. Peel and cut as needed to obtain a soluble copper-based composite material of the required length and width.

[0027] Weigh out 80 parts graphite and 8 parts Li7La3Zr2O by weight. 12 Mix with 2 parts carbon black and dry mix. Add a small amount of N-methylpyrrolidone and ball mill to obtain the original slurry. Then weigh 10 parts polyvinyl alcohol and add it to the original slurry. Continue to ball mill at a rotation speed of 300-350 r / min and a revolution speed of 2-5 r / min for 2-6 h. Use a high-shear emulsifier for high-speed stirring to obtain the slurry. Coat the prepared slurry onto the prepared soluble copper-based composite material and dry at 40-80℃. Roll press the dried electrode sheet and use a punching machine to punch the electrode sheet into small round sheets of the required size and shape, which is the soluble solid-state battery negative electrode composite electrode sheet.

[0028] Ionic conductivity test: The prepared blocking electrode was brought into close contact with the soluble solid-state battery negative electrode composite sheet to ensure good contact between the electrode and the sample, free of bubbles and impurities. The temperature was kept constant at 25℃. The test frequency range was set from 13 MHz to 10 Hz for AC impedance testing. The ionic conductivity was calculated based on the measured impedance value and the sample size. The test results are shown in Table 1.

[0029] The prepared negative electrode sheet was used as the test sample. The prepared negative electrode sheet was placed in a certain volume of aqueous solution. The aqueous solution was kept magnetically stirred. After 10 minutes, it was observed whether the negative electrode sheet was completely dissolved, partially dissolved, or not dissolved. Complete dissolution means that there are no lumps or flakes of material and the dissolved material in the aqueous solution is uniformly dispersed. Partial dissolution means that there are fragments or lumps of material in the solution. Not dissolved means that the negative electrode sheet is not dissolved. For easy recording, complete dissolution is marked as 3, partial dissolution is marked as 2, and not dissolved is marked as 1. The data of the specific embodiment are shown in the table below.

[0030] Furthermore, all the following embodiments and comparative examples were characterized using the same test methods, and the specific corresponding parameters are shown in the table below.

[0031] Comparative Example 1: Weigh out 80 parts by weight of graphite and 8 parts by weight of Li7La3Zr2O. 12 Mix with 2 parts carbon black and dry mix. Add a small amount of N-methylpyrrolidone and ball mill to obtain the original slurry. Then weigh 10 parts polyvinyl alcohol and add it to the original slurry. Continue ball milling and mixing. Use a high-shear emulsifier for high-speed stirring to obtain the slurry. Coat the prepared slurry onto the prepared copper foil and dry it at 50°C. Roll the dried electrode sheet with a roller press and use a punching machine to punch the electrode sheet into small round sheets of the required size and shape, which are the negative electrode sheets of solid-state batteries.

[0032] The physical performance parameters of the embodiments and comparative examples are shown in the table below.

[0033] .

[0034] As can be seen from the data in the table above, comparing the effects of different current collectors on the ionic conductivity of the electrode sheet in Example 1 and Comparative Example 1, as well as the overall dissolution performance of the electrode sheet, although the ionic conductivity of the prepared soluble solid-state battery negative electrode composite electrode sheet decreased, the entire negative electrode sheet could be completely dissolved, and the active material became powder and was uniformly dispersed in the solution, without large pieces of metal.

[0035] This invention is the first to propose the use of a combination of soluble copper-based composite material and negative electrode active material, and for the first time realizes a soluble negative electrode sheet, providing more possibilities for the development of solid-state batteries.

[0036] It should be further noted that this invention and the series of inventions are all attempts to achieve complete dissolution of solid-state batteries. Although the electrochemical performance has decreased, it has opened up new research areas.

[0037] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A soluble solid-state battery negative electrode composite sheet, characterized in that: The device consists of a copper-based composite current collector (2) and an active layer (1) of negative electrode material coated on the copper-based composite current collector (2). The copper-based composite current collector (2) is a soluble copper-based composite material prepared by copper powder, sodium alginate and conductive agent, with a thickness of 4-10 μm. It contains 60-90 wt% copper powder, 8-38 wt% sodium alginate and 2-5 wt% conductive agent. The copper powder is composed of two different copper powders with particle sizes of 0.2 μm and 1.1 μm in a weight ratio of 1:

1. The conductive agent is a mixture of graphene and carbon black in a weight ratio of 1:

2. By weight, the active layer (1) of negative electrode material contains 70-90 parts graphite, 4-12 parts polyvinyl alcohol and Li7La3Zr2O. 12 5-13 parts and carbon black 1-5 parts; polyvinyl alcohol is a medium molecular weight polyvinyl alcohol with a molecular weight of 120,000-150,000; the Li7La3Zr2O 12 Li7La3Zr2O was obtained by using LiOH•H2O as the lithium source, molding under pressure of 4MPa, and then sintering at 1000℃ for 15 h. 12 Ceramic shards.

2. The soluble solid-state battery negative electrode composite sheet according to claim 1, characterized in that, The negative electrode material active layer (1) comprises 80 parts graphite, 10 parts polyvinyl alcohol, and Li7La3Zr2O. 12 8 parts and 2 parts carbon black.

3. A method for preparing a soluble solid-state battery negative electrode composite sheet as described in claim 1, characterized in that, Includes the following steps: Step 1: Weigh copper powder, graphene, carbon black and sodium alginate, and vibrate and grind them in a ball mill mixing tube until they are uniformly mixed. Add ultrapure water and vibrate and grind until a slurry A with a viscosity of 1300-1600 mPa·s is formed. Coat slurry A onto a glass substrate, dry it in a vacuum oven at 50-90°C for 2-10 hours, roll it, and peel it off to obtain a soluble copper-based composite material. Step 2, weigh out graphite and Li7La3Zr2O 12 Mix carbon black evenly with N-methylpyrrolidone and ball mill to obtain slurry B; weigh polyvinyl alcohol and add it to slurry B, continue to ball mill at a rotation speed of 300-350 r / min and a revolution speed of 2-5 r / min for 2-6 h to mix, and use a high shear emulsifier for high-speed stirring to obtain negative electrode active slurry; Step 3: Coat the negative electrode active slurry onto the soluble copper-based composite material, dry it at 40-80°C, and roll it using a roller press to obtain the soluble solid-state battery negative electrode composite sheet.

4. The soluble solid-state battery negative electrode composite sheet as described in claim 1 is used in lithium batteries.

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