A lithium metal battery pole piece and a rolling apparatus, production system and method for pressing the same

Abstract

The application provides a lithium metal battery pole piece and a roller pressing device, a production system and a method for pressing the same, the roller pressing device comprises a roller pressing mechanism for roller pressing a strip, the roller pressing mechanism comprises a first compression roller arranged on one side of the strip, a second compression roller arranged on the opposite side of the strip and a pressure bearing roller in contact with the second compression roller; the centers of the first compression roller, the second compression roller and the pressure bearing roller are on the same straight line; the radius R1 of the first compression roller, the radius R2 of the second compression roller and the radius Rc of the pressure bearing roller satisfy the relationship R1>Rc>R2; and the number N of the pressure bearing rollers is greater than or equal to 1. The application adopts a multi-roller roller pressing device combined with a differential speed calendering process, further combined with lithium metal activation, can prepare a lithium ion battery pole piece with a width of up to 600 mm by one-step rolling, the thickness can be from 5 microns to 2 mm, can meet all design requirements of existing lithium metal batteries and future solid-state batteries, and has the advantages of low equipment cost and energy consumption cost, high safety and huge industrial application prospect.

Description

Technical Field

[0001] This invention belongs to the field of materials processing and relates to a lithium metal battery electrode and a rolling equipment, production system and method for pressing it. Background Technology

[0002] High-performance lithium metal anodes are crucial components of high-energy-density lithium batteries and solid-state batteries. Their size and performance directly affect the cell specifications, energy density, rate performance, and cycle life. Table 1 shows the commonly used preparation methods and performance characteristics of lithium metal anodes.

[0003] Table 1: List of conventional preparation methods for lithium metal anodes

[0004]

[0005] The current market for lithium metal anode production primarily utilizes Method 1 (Table 1), which can produce both pure lithium metal foil and composite lithium metal anodes combining lithium metal foil with other metal or non-metal substrates. Roll-to-roll industrial-scale mass production has already been achieved. However, the main drawback of Method 1 is the limitation imposed by current rolling techniques, resulting in lithium metal anodes with a width less than 400 mm. It also presents difficulties in producing lithium metal foils or composite foils with a thickness less than 50 µm. Methods 2–4 are advantageous in preparing lithium metal foils with a thickness of 5–20 µm, but face challenges in preparing foils thicker than 20 µm. Furthermore, these methods are not feasible for preparing lithium metal foils with a width greater than 400 mm. These dimensional limitations restrict the application of lithium metal anodes, impacting the design and performance improvement of high-energy-density lithium metal batteries and solid-state batteries.

[0006] Comparing these preparation methods reveals that Method 2 requires thermally melting lithium metal followed by coating, placing high demands on the temperature, stability, and safety of the thermal melting equipment. It can only produce composite lithium metal anodes with high-temperature resistant substrates. Method 3 also only produces composite lithium metal anodes; the high vacuum required for the equipment results in high equipment and energy costs. Method 4 employs an electrochemical preparation method, but the use of different electrolyte systems in the anode and cathode chambers places high demands on the structural design of the electrolytic cell and the lithium-ion exchange membrane. These limitations in equipment and operating conditions also affect the application of these methods.

[0007] Therefore, there is a need to find a production method that can produce batteries with a wider width and a greater range of thickness, which can meet all the design requirements of existing lithium metal batteries and future solid-state batteries, while also having lower equipment and energy costs and higher safety. Summary of the Invention

[0008] To address the problems existing in the prior art, this invention provides a lithium metal battery electrode sheet and a rolling mill, production system, and method for pressing it. This invention employs a multi-roll rolling mill combined with a differential rolling process, further incorporating lithium metal activation, enabling one-step rolling production of lithium-ion battery electrodes with widths up to 600mm and thicknesses ranging from 5µm to 2mm. This almost meets all design requirements of existing lithium metal batteries and future solid-state batteries, while also offering lower equipment and energy costs, higher safety, and significant potential for industrial application.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a roll forming device, the roll forming device including a roll forming mechanism for roll forming strip, the roll forming mechanism including a first pressure roller disposed on one side of the strip, a second pressure roller disposed on the opposite side of the strip, and a bearing roller in contact with the second pressure roller; the centers of the first pressure roller, the second pressure roller and the bearing roller are on the same straight line;

[0011] The radius R1 of the first pressure roller, the radius R2 of the second pressure roller, and the radius Rc of the bearing roller are related by the following condition: R1 > Rc > R2.

[0012] The number of pressure rollers N ≥ 1.

[0013] As a preferred embodiment of the present invention, when the number of pressure rollers N=1, the ratio of the radius R1 of the first pressure roller, the radius R2 of the second pressure roller and the radius Rc1 of the pressure roller is: R1:R2:Rc1=(4-6):1:(2-4).

[0014] As a preferred embodiment of the present invention, when the number of pressure rollers N=2, the pressure roller in contact with the second pressure roller is the first pressure roller, and the pressure roller in contact with the first pressure roller is the second pressure roller. The centers of the first pressure roller and the second pressure roller are on the same straight line as the centers of the first pressure roller and the second pressure roller. The relationship between the radius R1 of the first pressure roller, the radius R2 of the second pressure roller, the radius Rc1 of the first pressure roller, and the radius Rc2 of the second pressure roller is: R1:R2:Rc1:Rc2=(4-6):1:(2-4):(3-5); and Rc2>Rc1.

[0015] As a preferred embodiment of the present invention, when the number of pressure rollers N=1, the first pressure roller rotates clockwise during operation, the second pressure roller rotates counterclockwise during operation, and the pressure roller rotates clockwise during operation.

[0016] As a preferred embodiment of the present invention, when the number of pressure rollers N=2, the pressure roller in contact with the second pressure roller is the first pressure roller, and the pressure roller in contact with the first pressure roller is the second pressure roller. The centers of the first pressure roller and the second pressure roller are on the same straight line as the centers of the first pressure roller and the second pressure roller. The first pressure roller rotates clockwise during operation, and the second pressure roller rotates counterclockwise during operation.

[0017] As a preferred embodiment of the present invention, the roller pressing equipment is further provided with a sealed cavity to place the roller pressing equipment in a sealed space;

[0018] As a preferred embodiment of the present invention, a gas inlet is provided on the sealed cavity.

[0019] As a preferred embodiment of the present invention, the roller pressing equipment further includes a temperature control mechanism, which is connected to the first pressure roller and the second pressure roller respectively. Temperature control oil is injected into the pressure roller through a flow channel preset in the pressure roller and connected to an external oil temperature controller to form a circulation, thereby achieving the function of controlling the temperature of the pressure roller.

[0020] As a preferred embodiment of the present invention, the rolling equipment further includes a pressure regulating mechanism disposed between the first and second pressure rollers. The pressure regulating mechanism includes a calendering and coating pressure thrust system, a pressure reading and real-time adjustment system, and a micro-gap adjustment system. The calendering and coating pressure thrust system and the pressure reading and real-time adjustment system are connected to the second pressure roller, and the micro-gap adjustment system is connected to the roll gap between the first and second pressure rollers. The rolling pressure is set through the pressure thrust system, and the uniform and stable application of the rolling pressure throughout the entire calendering process is ensured through the real-time pressure regulating system and the micro-gap adjustment system.

[0021] Secondly, the present invention provides a production system for preparing lithium metal battery electrodes, the system including the aforementioned rolling equipment, and further including an unwinding mechanism for setting the material to be rolled and a winding mechanism for winding the rolled strip.

[0022] As a preferred embodiment of the present invention, a tension adjustment mechanism is provided between the unwinding mechanism and the winding mechanism.

[0023] As a preferred embodiment of the present invention, a slitting and trimming mechanism is provided between the rolling mechanism and the winding mechanism.

[0024] Thirdly, the present invention provides a method for using lithium metal battery electrodes with the aforementioned rolling equipment, the method comprising:

[0025] The strip to be pressed is fed into the roller pressing mechanism for pressing, and the ratio of the rotational speed of the first roller to the rotational speed of the second roller is controlled to be 1:(1-1.4).

[0026] As a preferred embodiment of the present invention, the rotational speed of the first pressure roller is 1-10 m / min, and the rotational speed of the second pressure roller is 1-14 m / min.

[0027] As a preferred embodiment of the present invention, the pressing is carried out in the presence of a protective gas and / or a reactive gas, preferably a reactive gas.

[0028] As a preferred embodiment of the present invention, the protective gas includes argon and / or helium.

[0029] As a preferred embodiment of the present invention, the reactive gas includes any one or a combination of at least two of oxygen, nitrogen, hydrogen, carbon dioxide or ammonia.

[0030] As a preferred embodiment of the present invention, the pressing is carried out under a slight negative pressure condition, and the pressure range is 0.04-0.08 MPa.

[0031] As a preferred embodiment of the present invention, during the pressing process, the surface temperature of the first pressure roller is 15℃-150℃, and the surface temperature of the second pressure roller is 15℃-150℃.

[0032] Fourthly, the present invention provides a lithium metal battery electrode sheet pressed using the aforementioned rolling equipment, wherein the width of the lithium metal battery electrode sheet is 0-600 mm and the thickness is 5-2000 μm.

[0033] As a preferred embodiment of the present invention, the lithium metal battery electrode has a width of 50-350 mm and a thickness of 20-100 μm.

[0034] As a preferred embodiment of the present invention, the lithium metal battery electrode comprises a single-layer lithium metal film or a lithium metal composite film.

[0035] As a preferred embodiment of the present invention, the lithium metal composite film is a composite film formed by a lithium metal layer and a substrate, including a single-sided composite film or a double-sided composite film.

[0036] As a preferred embodiment of the present invention, in the lithium metal composite film, the thickness of the lithium metal layer is 5-1500 μm, and the thickness of the substrate layer is 3-1500 μm.

[0037] As a preferred embodiment of the present invention, the substrate includes any one of a metal substrate, a non-metal substrate, or a metal-non-metal composite substrate.

[0038] As a preferred embodiment of the present invention, the metal material in the metal substrate and the metal-nonmetal composite substrate includes any one or a combination of at least two of copper, aluminum, nickel, zinc, titanium, gold, silver, platinum and stainless steel.

[0039] As a preferred embodiment of the present invention, the non-metallic material in the non-metallic substrate and the metal-non-metallic composite substrate includes any one or a combination of at least two of the following: carbon cloth, carbon plate, graphite-based film, resin-based reinforced carbon fiber composite film, conductive polymer film, and PET film.

[0040] As a preferred embodiment of the present invention, the single-sided composite film includes a single-sided composite film composed of a lithium metal layer and a metal substrate, a single-sided composite film composed of a lithium metal layer and a non-metallic substrate, or a single-sided composite film composed of a lithium metal layer and a metal-non-metallic composite substrate.

[0041] As a preferred embodiment of the present invention, the double-sided composite film includes any one of the following: a double-sided composite film composed of a lithium metal layer and a metal substrate, a double-sided composite film composed of a lithium metal layer and a non-metal substrate, or a double-sided composite film composed of a lithium metal layer and a metal-non-metal composite substrate.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] This invention, by employing an asymmetric multi-roller pressing mechanism and differential rolling, can reduce the pressure of the roller mechanism and can produce lithium metal foil or lithium metal composite foil with a width of up to 600 mm and a thickness from 5 µm to 2 mm, which can almost meet all the design requirements of existing lithium metal batteries and future solid-state batteries.

[0044] Simultaneously, by applying specific atmospheres before and after rolling, and controlling the roller temperature for different width and thickness requirements, the ductility of lithium metal strips can be improved, enabling the fabrication of ultra-thin and ultra-wide lithium metal foils or lithium metal composite films through a one-step rolling process. The lithium metal anode obtained through activation develops a protective layer on its surface, enhancing its stability and extending the battery's cycle life. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the roller pressing equipment in Embodiment 1 of the present invention;

[0046] Figure 2 This is a schematic diagram of the system structure in Embodiment 3 of the present invention;

[0047] Figure 3 This is a schematic diagram of the system structure in Embodiment 6 of the present invention;

[0048] Wherein, 1-first pressure roller; 2-second pressure roller; 3-first pressure bearing roller; 4-second pressure bearing roller; 5-strip material; 6-sealed cavity; 7, 71, 72, 73-unwinding mechanism; 8, 81, 82, 83-rewinding mechanism; 9-slitting and trimming mechanism. Detailed Implementation

[0049] To better illustrate the present invention and facilitate understanding of its technical solutions, the present invention will be further described in detail below. However, the following embodiments are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0050] The present invention provides a roll forming device, which includes a roll forming mechanism for roll forming strip. The roll forming mechanism includes a first pressure roller disposed on one side of the strip, a second pressure roller disposed on the opposite side of the strip, and a bearing roller in contact with the second pressure roller; the centers of the first pressure roller, the second pressure roller, and the bearing roller are on the same straight line.

[0051] The radius R1 of the first pressure roller, the radius R2 of the second pressure roller, and the radius Rc of the bearing roller are related by the following condition: R1 > Rc > R2.

[0052] The number of pressure rollers N≥1, specifically 1, 2, 3, etc.

[0053] In this invention, when the number of pressure rollers is greater than 1, each pressure roller is arranged sequentially along the center line of the second pressure roller, and the center of each pressure roller is on the same straight line as the center of the first pressure roller and the second pressure roller. The pressure roller that contacts the second pressure roller is the first pressure roller, and the pressure roller that contacts the first pressure roller is the second pressure roller, and so on.

[0054] The first pressure roller is a passive roller, and the second pressure roller is an active roller. Based on the positional relationship between the first and second pressure rollers and the bearing roller, this invention adjusts the radius ratio between the first and second pressure rollers and the bearing roller to ensure that the pressure applied to the strip during calendering is sufficiently low to meet the pressure requirements for preparing strips of different widths and thicknesses, especially for strips with very wide widths (width > 360 mm) and very thin thicknesses (5-20 µm). Simultaneously, by adjusting the diameter ratio between the first and second pressure rollers and the bearing roller, the roller speeds of the first and second pressure rollers can differ during operation, achieving differential calendering. This introduces shear force in addition to the rolling force, allowing lithium strip to be rolled to an ultra-thin thickness of 5-20 µm under relatively low pressure.

[0055] More specifically, the pressure roller configuration described in this invention can reduce the pressure required to thin wide lithium strips from a thickness greater than 2 mm to below 50 µm, or even to 5 µm, in a single step. According to experimental tests, rolling a 15 µm thick lithium foil requires a pressure of 55 T under a 350 mm width; extrapolating from this, rolling a 10 µm thick lithium foil under a 600 mm width would require a pressure exceeding 150 T, significantly increasing equipment costs and reducing the feasibility of mass production. However, with the design of this invention, only 20 T of pressure is needed to complete the pressing of the required lithium foil, reducing equipment costs and improving mass production capabilities.

[0056] As a preferred embodiment of the present invention, when the number of pressure rollers N=1, the ratio of the radius R1 of the first pressure roller, the radius R2 of the second pressure roller, and the radius Rc1 of the pressure roller is: R1:R2:Rc1=(4-6):1:(2-4), for example 4:1:2, 4:1:3, 5:1:2, 5:1:3, 5:1:4, 6:1:2, 6:1:3, or 6:1:4, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0057] As a preferred embodiment of the present invention, when the number of pressure rollers N=2, the pressure roller in contact with the second pressure roller is the first pressure roller, and the pressure roller in contact with the first pressure roller is the second pressure roller (4). The centers of the first pressure roller and the second pressure roller are on the same straight line as the centers of the first pressure roller and the second pressure roller, and the radius R1 of the first pressure roller, the radius R2 of the second pressure roller, the radius Rc1 of the first pressure roller, and the radius Rc2 of the second pressure roller are related as follows: R1:R2: Rc1:Rc2=(4-6):1:(2-4):(3-5); and Rc2>Rc1; R1:R2:Rc1:Rc2 is such as 4:1:2:3, 4:1:3:4, 5:1:2:3, 5:1:3:4, 5:1:4:5, 6:1:2:3, 6:1:2:4, 6:1:3:4 or 6:1:4:5, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0058] In this invention, the radii of the first pressure roller, the second pressure roller, and the bearing roller are in a certain proportional relationship. If the radii are less than this proportional range, greater pressure is required to obtain the same thickness of rolled lithium foil, thereby increasing the diameter of the pressure roller and the bearing roller, increasing the equipment cost and installation and use costs. Moreover, the uniformity of the lithium foil surface will decrease under a large roller diameter, thus affecting the performance of the lithium foil. If the radii are greater than this proportional range, the diameter of the first pressure roller will be too large and the diameter of the second pressure roller will be too small, thereby increasing their elastic flattening value and making it impossible to roll thin lithium foil.

[0059] As a preferred embodiment of the present invention, when the number of pressure rollers N=1, the first pressure roller rotates clockwise during operation, the second pressure roller rotates counterclockwise during operation, and the pressure roller rotates clockwise during operation.

[0060] As a preferred embodiment of the present invention, when the number of pressure rollers N=2, the pressure roller in contact with the second pressure roller is the first pressure roller, and the pressure roller in contact with the first pressure roller is the second pressure roller. The centers of the first pressure roller and the second pressure roller are on the same straight line as the centers of the first pressure roller and the second pressure roller. The first pressure roller rotates clockwise during operation, and the second pressure roller rotates counterclockwise during operation.

[0061] In this invention, the rotation directions of the first pressure roller and the second pressure roller are both towards the direction of travel of the lithium foil, while the rotation direction of the bearing roller is opposite to that of the second pressure roller, so that the rolling force can be better transmitted between the bearing roller and the rolling roller and act evenly on the lithium battery.

[0062] As a preferred embodiment of the present invention, the roller pressing equipment is further provided with a sealed cavity to place the roller pressing equipment in a sealed space.

[0063] As a preferred embodiment of the present invention, a gas inlet is provided on the sealed cavity.

[0064] In this invention, the rolling equipment is placed in a sealed cavity with a gas inlet. The purpose is to introduce a protective atmosphere and / or a reactive atmosphere during the rolling process, ensuring that rolling is carried out under specific atmospheric conditions and maintaining a slight negative pressure within the sealed cavity, allowing the atmosphere purity to reach over 90%. Rolling under these atmospheric conditions further improves the ductility of the lithium strip before and after rolling, making it easier to stretch and thin. Simultaneously, the surface of the fresh lithium metal foil after rolling is treated with a specific atmosphere, forming a protective layer on the lithium metal foil surface, thereby increasing the stability of the lithium metal foil and improving the cycle life of the battery.

[0065] As a preferred embodiment of the present invention, the rolling mill further includes a temperature control mechanism, which is connected to the first and second rolling mills respectively. Temperature-controlled oil is injected into the rolling mills through channels pre-installed in the rolling mills and connected to an external oil temperature controller to form a circulation, thereby controlling the rolling mill temperature. The temperature control mechanism can heat or cool the rolling mills to maintain a roll surface temperature of 15-150℃, adjusting the roll surface temperature according to the different thickness requirements of the lithium metal foil or composite film being processed.

[0066] In a preferred embodiment of the present invention, the rolling equipment includes a pressure control mechanism disposed between the first and second pressure rollers. This pressure control mechanism comprises a calendering and coating pressure thrust system, a pressure reading and real-time adjustment system, and a micro-gap adjustment system. The calendering and coating pressure thrust system and the pressure reading and real-time adjustment system are connected to the second pressure roller, while the micro-gap adjustment system is connected to the roll gap between the first and second pressure rollers. The rolling pressure is set via the pressure thrust system, and the uniform and stable application of the rolling pressure throughout the entire calendering process is ensured by the real-time pressure adjustment system and the micro-gap adjustment system. The pressure control mechanism can read the pressure during the calendering process in real time and provide feedback to adjust the calendering pressure within the required range.

[0067] As a preferred embodiment of the present invention, the rolling equipment further includes an unwinding mechanism for setting the material to be rolled and a winding mechanism for winding the rolled strip.

[0068] In this invention, there is no limit to the number of unwinding mechanisms, which can be set according to the type of lithium metal accessory being prepared, and may include protective film unwinding mechanism, lithium strip unwinding mechanism, transfer film unwinding mechanism, lithium strip unwinding mechanism, composite film unwinding mechanism, etc.

[0069] There is no limit to the number of winding mechanisms, which can be set according to the type of lithium metal accessory being prepared, and may include protective film winding mechanisms, composite film winding mechanisms, etc.

[0070] As a preferred embodiment of the present invention, a tension adjustment mechanism is provided between the unwinding mechanism and the winding mechanism. The number of such mechanisms is not limited and can be adjusted as needed.

[0071] As a preferred embodiment of the present invention, a slitting and trimming mechanism is provided between the rolling mechanism and the winding mechanism.

[0072] Secondly, the present invention provides a method for preparing lithium metal battery electrodes using the aforementioned rolling mill equipment, the method comprising:

[0073] The strip to be pressed is fed into the roller pressing mechanism for pressing. The ratio of the rotational speed of the first roller to the rotational speed of the second roller is controlled to be 1:(1-1.4), such as 1:1, 1:1.1, 1:1.2, 1:1.3 or 1:1.4, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0074] This invention employs differential rolling, which introduces shear force in addition to rolling force, allowing lithium strips to be rolled into ultra-thin thicknesses of 5–20 µm under relatively low pressure.

[0075] As a preferred embodiment of the present invention, the rotational speed of the first pressure roller is 1-10 m / min, such as 1 m / min, 2 m / min, 3 m / min, 4 m / min, 5 m / min, 6 m / min, 7 m / min, 8 m / min, 9 m / min or 10 m / min, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable; the rotational speed of the second pressure roller is 1-14 m / min, such as 1.2 m / min, 1.5 m / min, 2 m / min, 3 m / min, 4 m / min, 5 m / min, 6 m / min, 7 m / min, 8 m / min, 9 m / min, 10 m / min, 11 m / min, 12 m / min, 13 m / min or 14 m / min, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0076] As a preferred embodiment of the present invention, the pressing is carried out in the presence of a protective gas and / or a reactive gas, preferably a reactive gas.

[0077] As a preferred embodiment of the present invention, the protective gas includes argon and / or helium.

[0078] As a preferred embodiment of the present invention, the reactive gas includes any one or a combination of at least two of oxygen, nitrogen, hydrogen, carbon dioxide or ammonia. Typical but non-limiting combinations include combinations of oxygen and nitrogen, nitrogen and hydrogen, oxygen and carbon dioxide, carbon dioxide and ammonia, etc.

[0079] In this invention, calendering in the presence of a reactive gas can further improve the ductility of the lithium strip before and after calendering, making the lithium strip easier to stretch and thin. At the same time, a protective layer can be formed on the surface of the lithium metal foil after calendering, thereby increasing the stability of the lithium metal foil and improving the cycle life of the battery.

[0080] As a preferred embodiment of the present invention, the pressing is carried out under a slight negative pressure condition, the pressure range being 0.04-0.08 MPa, such as 0.04 MPa, 0.05 MPa, 0.06 MPa, 0.07 MPa, or 0.08 MPa, but not limited to the listed values; other unlisted values ​​within this range are also applicable. Performing the calendering under slight negative pressure conditions ensures that the purity of the protective gas and / or reactive gas during the calendering process is >90%.

[0081] As a preferred embodiment of the present invention, during the pressing process, the surface temperature of the first pressure roller is 15℃-150℃, such as 15℃, 20℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, 100℃, 110℃, 120℃, 130℃, 140℃, or 150℃, but not limited to the listed values; other unlisted values ​​within this range are also applicable. The surface temperature of the second pressure roller is 15℃-150℃, such as 15℃, 20℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, 100℃, 110℃, 120℃, 130℃, 140℃, or 150℃, but not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0082] In this invention, the surface temperatures of the first and second pressure rollers are adjusted accordingly based on the type of lithium metal foil or composite film to be processed and the temperature requirements for different thicknesses.

[0083] For example, when pressing pure lithium foil with a thickness of 5-20µm, the required roller surface temperature range for the first and second pressure rollers is 50℃-70℃; when pressing pure lithium foil with a thickness of 50-100µm, the required roller surface temperature range for the first and second pressure rollers is 30℃-50℃; and when pressing composite lithium foil with a thickness of 30-50µm on both sides of lithium foil / copper foil, setting the roller surface temperature to 70℃-90℃ yields the best results.

[0084] Thirdly, the present invention provides a lithium metal battery electrode sheet pressed using the aforementioned rolling mill, wherein the width of the lithium metal battery electrode sheet is 0-600mm, such as 50mm, 100mm, 150mm, 200mm, 250mm, 300mm, 350mm, 400mm, 450mm, 500mm, 550mm or 600mm, etc., but not limited to the listed values, and other unlisted values ​​within this range are also applicable; the thickness is 5-2000μm, such as 5μm, 10μm, 50μm, 100μm, 300μm, 500μm, 700μm, 1000μm, 1300μm, 1500μm, 1700μm or 2000μm, etc., but not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0085] As a preferred embodiment of the present invention, the lithium metal battery electrode has a width of 50-350 mm and a thickness of 20-100 μm.

[0086] As a preferred embodiment of the present invention, the lithium metal battery electrode comprises a single-layer lithium metal film or a lithium metal composite film.

[0087] As a preferred embodiment of the present invention, the lithium metal composite film is a composite film formed by a lithium metal layer and a substrate, including a single-sided composite film or a double-sided composite film.

[0088] As a preferred embodiment of the present invention, the thickness of the lithium metal layer in the lithium metal composite film is 5-1500 μm, for example, 5 μm, 10 μm, 50 μm, 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, 1000 μm, 1100 μm, 1200 μm, 1300 μm, 1400 μm, or 1500 μm, but is not limited to the listed values; other values ​​within this range not listed are also acceptable. The values ​​listed also apply; the thickness of the substrate layer is 3-1500μm, such as 3μm, 5μm, 10μm, 50μm, 100μm, 200μm, 300μm, 400μm, 500μm, 600μm, 700μm, 800μm, 900μm, 1000μm, 1100μm, 1200μm, 1300μm, 1400μm or 1500μm, but is not limited to the listed values. Other unlisted values ​​within this range also apply.

[0089] As a preferred embodiment of the present invention, the substrate includes any one of a metal substrate, a non-metal substrate, or a metal-non-metal composite substrate.

[0090] As a preferred embodiment of the present invention, the metal material in the metal substrate and the metal-nonmetal composite substrate includes any one or a combination of at least two of copper, aluminum, nickel, zinc, titanium, gold, silver, platinum and stainless steel.

[0091] As a preferred embodiment of the present invention, the non-metallic material in the non-metallic substrate and the metal-non-metallic composite substrate includes any one or a combination of at least two of the following: carbon cloth, carbon plate, graphite-based film, resin-based reinforced carbon fiber composite film, conductive polymer film, and PET film.

[0092] Typical examples of metal-nonmetal composite substrates include copper foil coated with PET copper film or conductive adhesive, and aluminum foil coated with conductive adhesive.

[0093] As a preferred embodiment of the present invention, the single-sided composite film includes a single-sided composite film composed of a lithium metal layer and a metal substrate, a single-sided composite film composed of a lithium metal layer and a non-metal substrate, or a single-sided composite film composed of a lithium metal layer and a metal-non-metal composite substrate.

[0094] As a preferred embodiment of the present invention, the double-sided composite film includes any one of the following: a double-sided composite film composed of a lithium metal layer and a metal substrate, a double-sided composite film composed of a lithium metal layer and a non-metal substrate, or a double-sided composite film composed of a lithium metal layer and a metal-non-metal composite substrate.

[0095] In this invention, the lithium metal battery electrode can be used as an electrode in liquid, liquid-solid hybrid, or solid-state lithium batteries.

[0096] The following are typical but non-limiting embodiments of the present invention:

[0097] Example 1:

[0098] This embodiment provides a roller pressing device, such as... Figure 1 As shown, the rolling mill includes a rolling mechanism for rolling strip. The rolling mechanism includes a first pressure roller 1 located on one side of the strip, a second pressure roller 2 located on the opposite side of the strip, and a first bearing roller 3 in contact with the second pressure roller 2. The bearing roller in contact with the first bearing roller 3 is a second bearing roller 4. The centers of the first pressure roller 1, the second pressure roller 2, the first bearing roller 3, and the second bearing roller 4 are on the same straight line. The radius R1 of the first pressure roller 1, the radius R2 of the second pressure roller 2, the radius Rc1 of the first bearing roller 3, and the radius Rc2 of the second bearing roller 4 are in the ratio 5:1:3:4. Simultaneously, the first pressure roller 1 rotates clockwise during operation, the second pressure roller 2 rotates counterclockwise, the first bearing roller 3 rotates clockwise, and the second bearing roller 4 rotates counterclockwise.

[0099] The roller pressing equipment is provided with a sealed cavity 6 to place the roller pressing equipment in a sealed space. A gas inlet is opened on the sealed cavity 6 and it is filled with protective gas argon. The pressure in the sealed space is 0.04-0.08MPa.

[0100] Example 2:

[0101] This embodiment provides a roller pressing device. Based on Embodiment 1, the roller pressing device is filled with reactive carbon dioxide gas, and the pressure within the sealed space is 0.04-0.08 MPa. It also includes a temperature control mechanism connected to the first and second rollers respectively. Temperature control oil is injected into the rollers through channels pre-set in the rollers and connected to an external oil temperature controller to form a circulation, thereby controlling the roller temperature. A pressure control mechanism is located between the first and second rollers. This pressure control mechanism includes a calendering and coating pressure thrust system, a pressure reading and real-time adjustment system, and a micro-gap adjustment system. The calendering and coating pressure thrust system and the pressure reading and real-time adjustment system are connected to the second roller, and the micro-gap adjustment system is connected to the roller gap between the first and second rollers.

[0102] Comparative Example A1:

[0103] This embodiment provides a roller pressing device, which is the same as that in Embodiment 2, except that the radius R1 of the first pressure roller 1, the radius R2 of the second pressure roller 2, the radius Rc1 of the first bearing roller 3, and the radius Rc2 of the second bearing roller 4 are in the following relationship: 3:1:1.5:2.

[0104] Example 3:

[0105] This embodiment provides a system and preparation method for pressing pure lithium metal foil using the equipment described in Embodiment 1, such as... Figure 2 As shown, the system includes the rolling equipment in Embodiment 1, and also includes an unwinding mechanism 7 and a winding mechanism 8, with a tension adjustment mechanism between the unwinding mechanism 7 and the winding mechanism 8; specifically, the unwinding mechanism 71 is used for unwinding the release protective film, the unwinding mechanism 72 is used for unwinding the lithium strip raw material, and the unwinding mechanism 73 is used for unwinding the transfer film; the winding mechanism 81 is used for winding the release protective film, the winding mechanism 82 is used for winding the lithium metal foil with the transfer film, and the winding mechanism 83 is used for winding the protective film on the surface of the lithium strip; at the same time, a slitting and trimming mechanism 9 is provided between the rolling equipment and the winding mechanism 82.

[0106] The method for pressing using the system is as follows:

[0107] The material to be pressed is unwound by the unwinding mechanism 7 and calendered by the rolling equipment. The rotation speed of the first pressure roller 1 is 6 m / min, the rotation speed of the second pressure roller 2 is 7.5 m / min, the rotation speed of the first bearing roller 3 is 7.5 m / min, and the rotation speed of the second bearing roller 4 is 7.5 m / min; the speed difference is 1:1.25; the pressure inside the pressing chamber is controlled at 0.06 MPa during the pressing process; after calendering, the release protective film is taken in by the winding mechanism 81, and the lithium metal foil with the transfer film is slit and trimmed by the slitting and trimming mechanism 9, and then taken in by the winding mechanism 82.

[0108] The lithium metal foil with transfer film pressed in this embodiment has a width of 250 mm and a thickness of 40 μm.

[0109] Example 4:

[0110] This embodiment provides a system and preparation method for pressing pure lithium metal foil using the equipment in Embodiment 2. Except for the rolling equipment, the structure of the system is the same as that in Embodiment 3.

[0111] The pressing method using the system is the same as in Example 3, except that the temperature of the first pressure roller 2 is controlled to 60°C and the temperature of the second pressure roller 2 is controlled to 60°C by the temperature control mechanism.

[0112] The lithium metal foil with transfer film pressed in this embodiment has a width of 350 mm and a thickness of 40 μm.

[0113] Comparative Example A2:

[0114] Comparative Example A2 provides a system and preparation method for pressing pure lithium metal foil using the equipment in Comparative Example A1. Except for the rolling equipment, the system structure is the same as that in Example 3.

[0115] The pressing method used in this comparative pressing is the same as that in Example 3.

[0116] The performance of lithium metal foils with transfer films pressed in Examples 3, 4 and Comparative Example A2 was tested. The test method was to form a button cell with the lithium foil and an excess of ternary cathode, and to conduct a charge-discharge test to test its first charge-discharge efficiency, thereby evaluating the stability of the lithium foil. The evaluation results are shown in Table 1.

[0117] Table 1: Test Results of Examples 3, 4 and Comparative Example A2

[0118] Examples / Comparative Examples First charge-discharge efficiency Example 3 95.6% Example 4 97.6% Comparative Example A2 89.3%

[0119] Example 5:

[0120] This embodiment provides a system and preparation method for pressing a single-sided lithium metal composite film using the equipment described in Embodiment 2, such as... Figure 2 As shown, the system includes the rolling equipment in Embodiment 2, and also includes an unwinding mechanism 7 and a winding mechanism 8, with a tension adjustment mechanism between the unwinding mechanism 7 and the winding mechanism 8; specifically, the unwinding mechanism 71 is used to unwind the release film, the unwinding mechanism 72 is used to unwind the lithium metal film with a protective film, and the unwinding mechanism 73 is used to unwind the substrate; the winding mechanism 81 is used to wind up the protective film, and the winding mechanism 82 is used to wind up the single-sided lithium metal composite film; at the same time, a slitting and trimming mechanism 9 is provided between the rolling equipment and the winding mechanism 82.

[0121] The method for pressing using the system is as follows:

[0122] The material to be pressed is unwound by the unwinding mechanism 7 and calendered by the roll forming equipment. The rotation speed of the first pressure roller 1 is 6 m / min, the rotation speed of the second pressure roller 2 is 7.5 m / min, the rotation speed of the first bearing roller 3 is 7.5 m / min, and the rotation speed of the second bearing roller 4 is 7.5 m / min. The rotation speed difference between the first pressure roller and the second pressure roller is 1:1.25. The pressure inside the pressing chamber is controlled at 0.06 MPa during the pressing process. After calendering, slitting and trimming, a single-sided lithium metal composite film is obtained.

[0123] The single-sided lithium metal composite film pressed in this embodiment has a width of 250 mm and a thickness of 50 µm.

[0124] The tensile strength of the single-sided lithium metal composite film pressed in this embodiment was tested, and the result was 56 MPa.

[0125] Example 6:

[0126] This embodiment provides a system and preparation method for pressing a double-sided lithium metal composite film using the equipment described in Embodiment 2, such as... Figure 3 As shown, the system includes the rolling equipment in Embodiment 2, and also includes an unwinding mechanism 7 and a winding mechanism 8, with a tension adjustment mechanism between the unwinding mechanism 7 and the winding mechanism 8; specifically, the unwinding mechanism 72 is used to unwind a single-sided lithium metal composite film, the unwinding mechanism 73 is used to unwind a protective film, and the unwinding mechanism 71 is used to unwind a lithium metal strip with a protective film; the winding mechanisms 81 and 82 are used to wind up the protective film, and the winding mechanism 83 is used to wind up a double-sided lithium metal composite film; at the same time, a slitting and trimming mechanism 9 is provided between the rolling equipment and the winding mechanism 82.

[0127] The method for pressing using the system is as follows:

[0128] The material to be pressed is unwound by the unwinding mechanism 7 and calendered by the roll forming equipment. The rotation speed of the first pressure roller 1 is 6 m / min, the rotation speed of the second pressure roller 2 is 7.5 m / min, the rotation speed of the first bearing roller 3 is 7.5 m / min, and the rotation speed of the second bearing roller 4 is 7.5 m / min. The rotation speed difference between the first pressure roller and the second pressure roller is 1.25. The pressure inside the control cavity is 0.06 MPa during the pressing process. After calendering, the protective film is wound up by the winding mechanism 81 and the winding mechanism 82. The winding mechanism 82 wound up the double-sided lithium metal composite film.

[0129] The double-sided lithium metal composite film pressed in this embodiment has a width of 250 mm and a thickness of 60 µm.

[0130] The tensile strength of the double-sided lithium metal composite film pressed in this embodiment was tested, and the result was 67 MPa.

[0131] As can be seen from the above embodiments and comparative examples, the present invention, by employing an asymmetric multi-roller pressing mechanism and differential rolling, can reduce the pressure of the roller mechanism and produce lithium metal foils or lithium metal composite foils with a width of up to 600 mm and a thickness from 5 µm to 2 mm, which can almost meet all the design requirements of existing lithium metal batteries and future solid-state batteries. At the same time, by controlling the roller temperature during rolling under specific atmospheres before and after rolling, and according to different width and thickness requirements, the resulting battery electrode can improve the first-charge efficiency of lithium metal batteries and increase cycle life.

[0132] The applicant declares that the detailed process equipment and process flow of this invention are illustrated through the above embodiments, but this invention is not limited to the above detailed process equipment and process flow, that is, it does not mean that this invention must rely on the above detailed process equipment and process flow to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials for the products of this invention, additions of auxiliary components, and selection of specific methods, all fall within the protection scope and disclosure scope of this invention.

Claims

1. A roll press apparatus characterized by, The roller pressing device comprises a roller pressing mechanism for pressing the strip, the roller pressing mechanism comprising a first pressing roller (1) arranged on one side of the strip, a second pressing roller (2) arranged on the opposite side of the strip, and a pressure bearing roller in contact with the second pressing roller (2); the centers of the first pressing roller (1), the second pressing roller (2) and the pressure bearing roller are on the same straight line; The radius R1 of the first pressing roller (1), the radius R2 of the second pressing roller (2) and the radius Rc of the pressure bearing roller satisfy the relationship R1>Rc>R2; The number N of the pressure bearing rollers is greater than or equal to 1; When the number N of the pressure bearing rollers is 1, the ratio of the radius R1 of the first pressing roller (1), the radius R2 of the second pressing roller (2) and the radius Rc1 of the pressure bearing roller is R1:R2:Rc1=(4-6):1:(2-4); When the number N of the pressure bearing rollers is 2, the pressure bearing roller in contact with the second pressing roller (2) is the first pressure bearing roller (3), the pressure bearing roller arranged in contact with the first pressure bearing roller (3) is the second pressure bearing roller (4), the centers of the first pressure bearing roller (3) and the second pressure bearing roller (4) and the centers of the first pressing roller (1) and the second pressing roller (2) are on the same straight line, and the radius R1 of the first pressing roller (1), the radius R2 of the second pressing roller (2), the radius Rc1 of the first pressure bearing roller (3) and the radius Rc2 of the second pressure bearing roller (4) satisfy the relationship R1:R2:Rc1:Rc2=(4-6):1:(2-4):(3-5); and Rc2>Rc1; The roller pressing device adopts differential speed rolling; the ratio of the rotating speed of the first pressing roller to the rotating speed of the second pressing roller is 1:(1-1.4); During the pressing process, the roller surface temperature of the first pressing roller (1) is 30-90℃, and the roller surface temperature of the second pressing roller (2) is 30-90℃.

2. The roll press apparatus according to claim 1, characterized by When the number N of the pressure bearing rollers is 1, the first pressing roller (1) rotates clockwise during operation, the second pressing roller (2) rotates counterclockwise during operation, and the pressure bearing roller rotates clockwise during operation.

3. The roll press apparatus according to claim 1, characterized by When the number N of the pressure bearing rollers is 2, the pressure bearing roller in contact with the second pressing roller (2) is the first pressure bearing roller (3), the pressure bearing roller arranged in contact with the first pressure bearing roller is the second pressure bearing roller (4), the centers of the first pressure bearing roller (3) and the second pressure bearing roller (4) and the centers of the first pressing roller (1) and the second pressing roller (2) are on the same straight line, and the first pressing roller (1) rotates clockwise during operation, the second pressing roller (2) rotates counterclockwise during operation, the first pressure bearing roller (3) rotates clockwise, and the second pressure bearing roller (4) rotates counterclockwise.

4. The roll press apparatus according to claim 1, characterized by The roller pressing device is further provided with a sealed cavity (6) to place the roller pressing device in a sealed space.

5. The roll press apparatus according to claim 4, characterized by A gas inlet is formed on the sealed cavity (6).

6. The roll press apparatus according to claim 1, characterized by The roller pressing device further comprises a temperature control mechanism connected to the first pressing roller (1) and the second pressing roller (2), respectively, which injects temperature control oil into the pressing roller through the flow channel prearranged in the pressing roller, and forms a cycle connected to the external oil temperature machine.

7. The roll press apparatus according to claim 1, characterized by The roller pressing device further comprises a pressure regulating mechanism arranged between the first pressure roller (1) and the second pressure roller (2), wherein the pressure regulating mechanism comprises a calendering film pressure thrust system, a reading and real-time pressure adjusting system, and a reading and real-time micro-gap adjusting system; the calendering film pressure thrust system and the reading and real-time pressure adjusting system are connected to the second pressure roller (2), and the reading and real-time micro-gap adjusting system is connected to the roll gap of the first pressure roller (1) and the second pressure roller (2).

8. A production system for preparing a lithium metal battery pole piece, characterized by, The system comprises the roller pressing device according to any one of claims 1-7, and further comprises an unwinding mechanism for arranging the material to be pressed and a winding mechanism for winding the material after being pressed.

9. The production system of claim 8, wherein, A tension adjusting mechanism is arranged between the unwinding mechanism and the winding mechanism.

10. The production system of claim 8, wherein, A slitting and trimming mechanism is arranged between the roller pressing mechanism and the winding mechanism.

11. A method of pressing a lithium metal battery electrode sheet using the roll press apparatus of any one of claims 1-7, characterized in that, The method comprises: The material to be pressed is sent into the roller pressing mechanism for pressing, and the ratio of the rotating speed of the first pressure roller (1) to the rotating speed of the second pressure roller (2) is 1:(1-1.4).

12. The method of claim 11, wherein, The rotating speed of the first pressure roller (1) is 1-10 m / min, and the rotating speed of the second pressure roller (2) is 1-14 m / min.

13. The method of claim 11, wherein, The pressing is performed in the presence of a protective gas and / or a reactive gas.

14. The method of claim 11, wherein, The pressing is performed in the presence of a reactive gas.

15. The method of claim 13, wherein, The protective gas comprises argon and / or helium.

16. The method of claim 13, wherein, The reactive gas comprises any one or a combination of at least two of oxygen, nitrogen, hydrogen, carbon dioxide, and ammonia.

17. The method of claim 11, wherein, The pressing is performed under a micro-negative pressure condition, and the pressure range is 0.04-0.08 MPa.

18. The method of claim 11, wherein, During the pressing, the roll surface temperature of the first pressure roller (1) is 15-150 ℃, and the roll surface temperature of the second pressure roller (2) is 15-150 ℃.

19. A lithium metal battery electrode sheet pressed using the roll press apparatus of any one of claims 1-7. The width of the lithium metal battery electrode sheet is 0-600 mm, and the thickness is 5-2000 μm.

20. The lithium metal battery pole piece of claim 19, wherein, The width of the lithium metal battery electrode sheet is 50-350 mm, and the thickness is 20-100 μm.

21. The lithium metal battery pole piece of claim 19, wherein, The lithium metal battery electrode sheet comprises a single-layer lithium metal film or a lithium metal composite film.

22. The lithium metal battery pole piece of claim 21, wherein, The lithium metal composite film is a composite film formed by a lithium metal layer and a substrate, and comprises a single-sided composite film or a double-sided composite film.

23. The lithium metal battery pole piece of claim 21, wherein, In the lithium metal composite film, the thickness of the lithium metal layer is 5-1500 μm, and the thickness of the substrate layer is 3-1500 μm.

24. The lithium metal battery pole piece of claim 22, wherein, The substrate comprises any one of a metal substrate, a non-metal substrate, or a metal-non-metal composite substrate.

25. The lithium metal battery pole piece of claim 24, wherein, The metal material in the metal substrate and the metal-non-metal composite substrate comprises any one or a combination of at least two of copper, aluminum, nickel, zinc, titanium, gold, silver, platinum, and stainless steel.

26. The lithium metal battery pole piece of claim 24, wherein, The non-metal material in the non-metal substrate and the metal-non-metal composite substrate comprises any one or a combination of at least two of carbon cloth, carbon plate, graphite-based film, resin-based reinforced carbon fiber composite film, conductive polymer film, and PET film.

27. The lithium metal battery pole piece of claim 22, wherein, The single-sided composite film comprises a single-sided composite film composed of a lithium metal layer and a metal substrate, a single-sided composite film composed of a lithium metal layer and a non-metal substrate, or a single-sided composite film composed of a lithium metal layer and a metal-non-metal composite substrate.

28. The lithium metal battery pole piece of claim 22, wherein, The double-sided composite film includes any one of a double-sided composite film composed of a lithium metal layer and a metal substrate, a double-sided composite film composed of a lithium metal layer and a non-metal substrate, or a double-sided composite film composed of a lithium metal layer and a metal-nonmetal composite substrate.

Images