Cathode current collector for lithium-sulfur battery and anode current collector for lithium metal battery or lithium ion battery

Abstract

The utility model discloses a cathode current collector of a lithium-sulfur battery and an anode current collector of a lithium metal battery or a lithium ion battery, wherein the cathode current collector comprises a magnesium-lithium alloy strip or mesh belt and a cathode active material attached to the magnesium-lithium alloy strip or mesh belt. The anode current collector comprises a magnesium-lithium alloy strip or mesh belt and metal lithium attached to the magnesium-lithium alloy strip or mesh belt. According to the utility model, the magnesium-lithium alloy is used as the cathode and anode current collectors of the lithium-sulfur battery or the lithium metal battery, and the specific surface area of the metal lithium is increased by an electro-deposition method, so that the cycle life and the overall performance of the battery can be remarkably improved; the problem that the current conduction in the electrode is failed and the electrochemical reaction is terminated due to the fact that the traditional metal lithium foil anode is extremely easy to break in the circulating process is solved, and the low-temperature performance and the rate capability of the battery are improved. And the magnesium-lithium alloy in the cathode improves the stability of the cathode material by supplementing lithium ions, so that the cycle life of the battery is further prolonged.

Description

TECHNICAL FIELD

[0001] The utility model relates to lithium sulfur battery or lithium metal battery technical field, especially relate to a kind of cathode current collector for lithium sulfur battery and lithium metal battery or lithium ion battery anode current collector. BACKGROUND

[0002] At present, lithium sulfur battery and lithium metal battery have great application potential in high energy density and long cycle life. However, so far, the negative electrode (anode) of the above two types of batteries uses single metal lithium foil. This design has significant defects in the battery charging and discharging cycle process. Due to the lack of current collector as the support and conductive network of metal lithium foil, metal lithium foil is prone to breakage and uneven deposition of lithium metal in the early stage of battery charging and discharging cycle, resulting in short circuit and open circuit failure of the battery, which seriously limits the cycle life of the battery. In addition, the positive electrode (cathode) material is also prone to capacity decay and stability decline due to depletion of lithium source during the cycle process.

[0003] In chemical batteries, especially lithium sulfur batteries or lithium metal batteries, the current method is to use metal lithium foil as the negative electrode (anode) directly, without current collector to carry metal lithium, which will cause lithium foil to break in the early cycle, resulting in negative electrode (anode) failure and battery failure.

[0004] Therefore, Chinese utility model patent authorization announcement No. CN110828829B patent points out the importance and solution of 3D current collector, but the raw material of the current collector used is a metal material with relatively heavy unit mass, which is contrary to the prospect of improving the specific energy of the battery. At the same time, it needs to deposit or electroplate noble metals such as gold and silver on the current collector, which is complex in process and high in cost. It is not conducive to large-scale manufacturing and industrial application.

[0005] In Chinese utility model patent authorization announcement No. CN103794800B patent, foam metal is used as the carrier of metal lithium. Under current technology, although the uniformity of some metal foam materials has been greatly improved, there is still a big gap in consistency compared with mechanical manufacturing and processing methods. The manufacturing process of the battery often guarantees the consistency by monitoring the weight of each component material, so the difference in consistency of the above materials has a great impact on the consistency of single battery, which will eventually affect the cycle life of the battery. At the same time, the processing cost of foam metal is also relatively high.

[0006] The core of the Chinese utility model patent authorization announcement number CN110061191B is: the current collector as the framework is three-dimensional foam copper, and the metal lithium is dispersed in the interstices of the three-dimensional foam copper; wherein, the metal nanomaterial is grown on the surface of the three-dimensional foam copper, forming a lithiumophilic surface; the three-dimensional foam copper forms an alloy with lithium through the metal nanomaterial. The same problems as the above patent are: 1: consistency; 2: heavy metal does not meet the lightweight demand; 3: the surface of the metal copper needs to be treated in a complex way to make the metal lithium compatible with it. The process is complex, the cost is high, and industrialization is difficult.

[0007] The Chinese utility model patent authorization announcement number CN109713224B also uses foam metal as the current collector, which also has the same problems as above.

[0008] In addition, using foam metal as the negative (anode) current collector and depositing lithium metal in the foam can theoretically prevent the battery from failing due to the problem of the negative (anode) metal lithium. However, due to the uniformity and consistency of the foam preparation, the weight of the deposited metal lithium in a certain area or volume may vary. The battery manufacturing process often involves the weight of various components and parts, so the difference will seriously affect the consistency of the chemical battery reaction, ultimately leading to early failure of the battery.

[0009] In addition, the inconsistency and unevenness may cause the following problems:

[0010] 1. Inconsistent battery performance: uneven metal lithium deposition may cause differences in battery performance between batteries, or even inconsistent performance among batteries in the same batch.

[0011] 2. Difficulty in quality control: Each component in the battery manufacturing process usually requires precise material weight control and proportioning to ensure the stability and consistency of the battery. The weight difference introduced by foam metal may pose challenges to these controls, thereby affecting the overall quality and life of the battery.

[0012] 3. Foam copper and foam nickel are high in processing cost, and have poor compatibility with metal lithium. After surface chemical treatment, the metal lithium deposition can meet the requirements as much as possible, which brings complex processing and high cost. In high-energy battery design, the lighter the current collector, the better, and lightweight metals are needed. Utility model content

[0013] One of the technical problems to be solved by the present application is to provide a cathode current collector for a lithium-sulfur battery or an anode current collector for a lithium metal battery or a lithium ion battery, which has low manufacturing cost and is easy to industrialize.

[0014] Another technical problem to be solved by the present application is to provide a cathode current collector for a lithium-sulfur battery or an anode current collector for a lithium metal battery or a lithium ion battery, which has low manufacturing cost and is easy to industrialize.

[0015] As the cathode current collector for a lithium-sulfur battery of the first aspect of the present application, it comprises a magnesium-lithium alloy strip or mesh belt and a cathode active material attached to the magnesium-lithium alloy strip or mesh belt.

[0016] As the anode current collector for a lithium metal battery or a lithium ion battery of the second aspect of the present application, it comprises a magnesium-lithium alloy strip or mesh belt and metal lithium attached to the magnesium-lithium alloy strip or mesh belt.

[0017] In a preferred embodiment of the present application, the lithium content in the magnesium-lithium alloy strip or mesh belt is between 3-20wt%.

[0018] In a preferred embodiment of the present application, the lithium content in the magnesium-lithium alloy strip or mesh belt is between 5-15wt%.

[0019] In a preferred embodiment of the present application, the cathode active material is sulfur or sulfide.

[0020] In a preferred embodiment of the present application, the magnesium-lithium alloy mesh belt is a tensile mesh (also known as an expanded mesh).

[0021] In a preferred embodiment of the present application, the metal lithium is attached to the magnesium-lithium alloy strip or mesh belt by mechanical means using a metal lithium foil.

[0022] In a preferred embodiment of the present application, the metal lithium is attached to the magnesium-lithium alloy strip or mesh belt by compression means using a metal lithium foil.

[0023] In a preferred embodiment of the present application, the metal lithium is attached to the magnesium-lithium alloy strip or mesh belt by electrodeposition.

[0024] In a preferred embodiment of the present application, the cathode active material is uniformly attached to the magnesium-lithium alloy strip or mesh belt by wet or dry coating method.

[0025] In a preferred embodiment of the utility model, the magnesium-lithium alloy strip or mesh belt is made by rolling process.

[0026] Due to the above technical scheme, the utility model has the following advantages:

[0027] 1. The magnesium-lithium alloy strip or mesh belt is used as the current collector to carry metal lithium and cathode active material, wet or dry electrode coating mode is used, the active material coated per unit area is much higher than that of the traditional transfer coating mode, the specific surface area of the electrode is increased, the electrode reaction efficiency is improved, and the energy density of the battery is greatly improved.

[0028] 2. As the negative electrode (anode) current collector, the stability of the current conduction and the lithium metal adhesion surface area of the negative electrode (anode) can be ensured during the whole battery life, thereby the battery life can be greatly prolonged. Meanwhile, the three-dimensional current collector structure also increases the specific surface area of the anode, the chemical reaction rate in the chemical battery system can be greatly improved, good low-temperature performance and rate characteristics are formed, the stress and damage of the metal lithium foil attached to the surface in the cycle process can be reduced, and the battery cycle life is prolonged.

[0029] 3. Metal magnesium is one of the lightest metals, and the magnesium-lithium alloy formed by adding lithium can improve the ductility of the material, facilitate subsequent rolling foil processing and tensile net manufacturing. Pure metal magnesium is not suitable for this application due to insufficient ductility.

[0030] 4. The magnesium-lithium alloy is prepared by alloy smelting method, and is processed into magnesium-lithium alloy strip or mesh belt in the shape of current collector, so that the magnesium-lithium alloy has good ductility and mechanical strength.

[0031] 5. The lithium source (lithium supplement) in the magnesium-lithium alloy is used to improve the stability of the positive electrode (cathode) material, thereby greatly prolonging the cycle life of the battery.

[0032] 6. High-purity metal lithium foil is used, and the metal lithium is uniformly attached or deposited on the magnesium-lithium alloy strip or mesh belt by mechanical pressing or electrodeposition method, so as to improve the specific surface area of the negative electrode (anode).

[0033] 7. The positive electrode (cathode) active material (such as sulfur and sulfur compounds) is attached to the surface of the magnesium-lithium alloy strip or mesh belt by coating method, which can ensure material heavy coating and uniform distribution.

[0034] 8. In the process of battery charging and discharging, the lithium source in the magnesium-lithium alloy provides additional lithium ions (lithium supplement), and improves the stability of the cathode material.

[0035] 9. Selecting magnesium-lithium alloys with lithium content in the range of 3-20 wt% can slow down the dissolution rate of lithium to some extent while maintaining the mechanical strength of the magnesium-lithium alloy.

[0036] 10. The magnesium-lithium alloy current collector provides stable mechanical support, preventing accidental breakage of the metal lithium foil during battery charge and discharge cycles due to the randomness of metal lithium deposition areas, thereby greatly extending the cycle life of the battery. The magnesium-lithium alloy mesh in the cathode improves the stability of the cathode material by replenishing lithium ions.

[0037] 11. Due to the improved stability of the anode and cathode, the battery maintains better performance and higher energy density during charging and discharging.

[0038] 12. Both the method of rolling the metal lithium foil and the method of electrodeposition can increase the specific surface area of the anode, which can improve the low-temperature performance and rate performance of the battery.

[0039] 13. The use of magnesium-lithium alloy current collectors can reduce the safety hazards caused by the breakage of metal lithium foil, improving the safety of the battery. The improved stability of the cathode material also helps to prevent overcharging and other adverse reactions.

[0040] 14. Reduce physical damage to metal lithium: The current collector can share the stress in the battery, reducing the risk of deformation and breakage of metal lithium during charging and discharging.

[0041] 15. Improve the cycle stability of the battery: By improving the anode design, the resistance change and performance degradation during battery cycling can be reduced, extending the cycle life of the battery.

[0042] 16. Improve safety: Reduce local hot spots and safety hazards that occur during charging of metal lithium, improve the safety performance of the battery.

[0043] 17. Magnesium-lithium alloy is a very light metal material, which is very suitable for use as a battery negative electrode (anode) current collector, which helps to improve the energy density and overall weight efficiency of the battery.

[0044] 18. The magnesium-lithium alloy contains metal lithium components, which makes the subsequent metal lithium electrodeposition or mechanical rolling process better combined with the base material, improving the stability and cycle life of the anode.

[0045] 19. The three-dimensional network material of magnesium-lithium alloy constructed by mechanical stretching process can achieve high uniformity and consistency of porosity, which is crucial for weight control and performance stability in the battery manufacturing process.

[0046] 20. Using conventional mechanical processing modes (such as stretching processes) to process magnesium-lithium alloy foils can be more easily implemented compared to methods such as foaming metals, and can be optimized in terms of cost and technical complexity.

[0047] 21. The use of mechanical stretching net (expanding net) processing mode for magnesium-lithium alloy can effectively utilize magnesium-lithium alloy foil materials with little waste, which is very important for cost control and sustainability.

[0048] 22. Compared to other high-cost processing methods such as punching or laser drilling, the processing cost of mechanical stretching net is generally more economical, as it does not involve complex equipment or high-energy-consuming process steps. The mechanical stretching net processing flow is relatively simple, easy to implement and control, reducing technical risks and the influence of variables in the manufacturing process. This processing method can be easily scaled up to mass production, adapting to the high yield demand in battery manufacturing. In terms of mass production, the mechanical stretching net processing flow can further improve efficiency and consistency through automation and process optimization, ensuring the stability of product quality and production efficiency. This is a crucial factor for meeting market demand, reducing unit cost, and promoting the commercial success of new technologies. Mechanical stretching net as a processing mode indeed effectively solves the problems of wasted materials and high costs, especially in the application of lightweight metal materials such as magnesium-lithium alloy, with significant advantages. This method not only helps to improve production efficiency, but also reduces manufacturing costs, laying the foundation for the commercialization and widespread application of new technologies.

[0049] The magnesium-lithium alloy is used as the anode three-dimensional current collector, which has the following main advantages: 1. providing an excellent conductive attachment surface area for the lithium source, 2. maintaining the integrity of the current collector and the consistency of current distribution throughout the battery's life, 3. enabling the metal lithium to have a higher specific surface area than the foil, increasing the chemical reaction rate, and significantly improving the low-temperature performance and rate performance of the chemical battery.

[0050] The magnesium-lithium alloy is used as the cathode or anode current collector of lithium-sulfur batteries or lithium metal batteries or other lithium-ion batteries with metal lithium negative electrodes, and the specific surface area of metal lithium is increased through electrodeposition, which can significantly improve the cycle life and overall performance of the battery, solve the problem of easy breakage of traditional metal lithium foil anodes during cycling, and improve the low-temperature performance and rate performance of the battery. The magnesium-lithium alloy net in the cathode improves the stability of the cathode material by supplementing lithium ions, further extending the cycle life of the battery. This innovative method is expected to play an important role in the development and application of high-energy-density batteries. BRIEF DESCRIPTION OF DRAWINGS

[0051] Figure 1The utility model discloses a magnesium lithium alloy mesh belt (stretching net) structure schematic diagram.

[0052] Figure 2 The utility model discloses another magnesium lithium alloy mesh belt (stretching net) structure schematic diagram.

[0053] Figure 3 The structure schematic diagram of cathode current collector of example 1.

[0054] Figure 4 The structure schematic diagram of cathode current collector of example 2.

[0055] Figure 5 The structure schematic diagram of anode current collector of example 3.

[0056] Figure 6 The structure schematic diagram of anode current collector of example 4.

[0057] Figure 7 The schematic diagram of pressing metal lithium foil to magnesium lithium alloy mesh belt (stretching net) of example 5. DETAILED DESCRIPTION

[0058] The utility model will be further described below in connection with the drawings and specific embodiment. EMBODIMENT

[0059] Referring to Figure 3 , the cathode current collector for lithium-sulfur battery includes magnesium lithium alloy strip 1a and positive electrode (cathode) active material 2a that is coated and adhered on magnesium lithium alloy strip 1a uniformly. The positive electrode (cathode) active material is sulfur or sulfide, wherein the sulfur content is greater than 50%, such as sulfur carbon mixed material, polymerized sulfur / carbon mixed material, lithium sulfide / carbon mixed material. The active material coating can adopt double-sided rolling coating mode. The lithium content in magnesium lithium alloy strip 1a is between 3-20wt%, preferably between 5-15wt%.

[0060] The magnesium lithium alloy strip is made by rolling process, and the thickness is 0.02-0.09mm.

[0061] The process of coating positive electrode (cathode) active material 2a on magnesium lithium alloy strip 1a is single-sided transfer coating mode EMBODIMENT

[0062] Referring to Figure 4, a positive electrode (cathode) current collector for lithium-sulfur battery, comprising a magnesium-lithium alloy mesh belt 1b and a positive electrode (cathode) active material 2b uniformly attached on the magnesium-lithium alloy mesh belt 1b by electrodeposition. The positive electrode (cathode) active material 2b is sulfur or sulfide, such as sulfur / carbon / binder mixed material, polymerized sulfur / carbon / binder mixed material, lithium sulfide / carbon / binder mixed material. The coating mode can be double-sided roll coating mode. The lithium content in the magnesium-lithium alloy mesh belt 1b is between 3-20wt%, preferably between 5-15wt%.

[0063] The process of electrodeposition of the positive electrode (cathode) active material 2a on the magnesium-lithium alloy mesh belt 1b is to use the lithium-magnesium alloy mesh as the negative electrode and the metal lithium as the positive electrode, to use the organic solvent capable of dissolving the metal lithium as the electrolyte, and to deposit the metal lithium on the lithium-magnesium alloy mesh belt by constant current charging, and the deposition thickness and morphology can be controlled by adjusting the current density and process time.

[0064] The magnesium-lithium alloy mesh belt 1b is a tensile mesh structure as shown in Figure 1 and Figure 2 , and the thickness is 0.02-0.09mm. It can also be made by rolling process, and the thickness is 0.02-0.09mm, and the holes are round holes or special-shaped holes. Embodiment

[0065] Referring to Figure 5 , an anode current collector for lithium metal battery or lithium ion battery, comprising a magnesium-lithium alloy strip 1c and metal lithium 3a uniformly attached on the magnesium-lithium alloy strip 1c by electrodeposition, and the lithium content in the magnesium-lithium alloy strip 1c is between 3-20wt%, preferably between 5-15wt%.

[0066] The magnesium-lithium alloy strip is made by rolling process, and the thickness is 0.02-0.09mm. Embodiment

[0067] Referring to Figure 6 , an anode current collector for lithium metal battery or lithium ion battery, comprising a magnesium-lithium alloy mesh belt 1d and metal lithium 3b uniformly attached on the magnesium-lithium alloy mesh belt 1d by electrodeposition, and the lithium content in the magnesium-lithium alloy mesh belt 1d is between 3-20wt%, preferably between 5-15wt%.

[0068] The magnesium-lithium alloy mesh belt 1b is a tensile mesh structure as shown in Figure 1 and Figure 2 , and the thickness is 0.02-0.09mm. It can also be made by rolling process, and the thickness is 0.02-0.09mm, and the holes are round holes or special-shaped holes. Embodiment

[0069] Referring to Figure 7An anode current collector for lithium metal or lithium ion batteries comprising a magnesium-lithium alloy mesh ribbon 1e and metallic lithium 3c attached to the magnesium-lithium alloy mesh ribbon 1d by means of a pressing process, the lithium content in the magnesium-lithium alloy mesh ribbon 1e being between 3 and 20 wt%, preferably between 5 and 15 wt%.

[0070] The magnesium-lithium alloy mesh ribbon 1b is Figure 1 and Figure 2 a stretched mesh structure as shown in the drawing, having a thickness of 0.02 to 0.09 mm, which can also be produced by means of a rolling process, having a thickness of 0.02 to 0.09 mm, and having round or shaped holes.

Claims

1. Cathode current collector for lithium-sulfur batteries, characterized by, The magnesium-lithium alloy strip or web and a cathode active material attached to the magnesium-lithium alloy strip or web.

2. The cathode current collector for lithium-sulfur batteries of claim 1, wherein, The lithium content in the magnesium-lithium alloy strip or web is between 3-20wt%.

3. The cathode current collector for lithium-sulfur batteries of claim 1, wherein, The cathode active material of the positive electrode is sulfur element or compound of sulfur, wherein the proportion of sulfur element is greater than 50%.

4. The cathode current collector for lithium-sulfur batteries of claim 1, wherein, The magnesium-lithium alloy web is a tensile web.

5. The cathode current collector for lithium-sulfur batteries according to claim 1, wherein The magnesium-lithium alloy strip or web is made by rolling process.

6. The cathode current collector for lithium-sulfur batteries of claim 1, wherein, The cathode active material is uniformly attached to the magnesium-lithium alloy strip or web by wet transfer coating or dry extrusion coating.

7. Anode current collector for a lithium metal battery or a lithium-ion battery, characterized in that, The magnesium-lithium alloy strip or web and metal lithium attached to the magnesium-lithium alloy strip or web.

8. The anode current collector for a lithium metal or lithium ion battery of claim 7, wherein, The lithium content in the magnesium-lithium alloy strip or web is between 3-20wt%.

9. The anode current collector for a lithium metal or lithium ion battery of claim 7, wherein, The magnesium-lithium alloy web is a tensile web.

10. The anode current collector for a lithium metal or lithium ion battery of claim 7, wherein, The magnesium-lithium alloy strip or web is made by rolling process.

11. The anode current collector for a lithium metal or lithium ion battery of claim 7, wherein, The lithium is attached to the magnesium-lithium alloy strip or web by mechanical method using metal lithium foil.

12. The anode current collector for a lithium metal or lithium ion battery of claim 7, wherein, The lithium is attached to the magnesium-lithium alloy strip or web by pressing method using metal lithium foil.

13. The anode current collector for a lithium metal or lithium ion battery of claim 7, wherein, The lithium is attached to the magnesium-lithium alloy strip or web by electrodeposition method.

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