Lithium primary button battery, preparation method thereof and electronic device

Abstract

To provide a lithium primary button type battery having excellent discharge performance, good stability and reliability, its manufacturing method, and an electronic apparatus.SOLUTION: A lithium primary button battery comprises a battery case and a battery core module located inside the battery case, the battery core module comprises a negative electrode (3), a negative electrode modification membrane (4), a separator (5, 6) and a positive electrode (7) which are sequentially stacked, a surface of the negative electrode (3) close to the negative electrode modification membrane (4) is provided with a concave groove (9), and the negative electrode modification membrane (4) is tightly embedded in the concave groove (9).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] This application claims priority to a Chinese patent application bearing application number 202411045595.2 filed with the China Patent Office on July 31, 2024, and to a Chinese patent application bearing application number 202421847565.9 filed with the China Patent Office on July 31, 2024, the entire contents of which are incorporated herein by reference.

[0002] This application relates to the technical field of battery materials, and in particular to lithium primary button batteries, methods for making same, and electronic devices. [Background technology]

[0003] A lithium primary battery is a high-energy chemical galvanic battery, commonly known as a lithium battery. It uses metallic lithium as the negative electrode, a solid salt or a salt soluble in an organic solvent as the electrolyte, and a metal oxide or other solid or liquid oxidizer as the positive electrode active material. It is widely used in various fields such as smart watches, smart transportation, smart security, and medical equipment. With the widespread application of Internet of Things technology, user application environments are becoming increasingly harsh, and the requirements for battery output capacity and stability in extreme environments are becoming increasingly higher. Therefore, the requirements for the structural stability of the battery core throughout its life cycle are also becoming higher.

[0004] Extreme environments mainly include extreme conditions such as high temperature, low temperature, high pressure, and strong vibration. These extreme environmental conditions place higher requirements on the performance and reliability of batteries. For example, in low-temperature environments, battery materials need to have better low-temperature performance to avoid the leaching phenomenon and shuttle effect of positive electrode active ions and side reactions between the electrode material and the electrolyte, and maintain the stability and reliability of the battery. In high-pressure environments, battery structures need to be more robust and safe to prevent battery rupture and explosion. In strong vibration environments, battery structures and fixing methods need to be more stable and reliable to prevent battery displacement or detachment. Therefore, to adapt to these extreme environments, optimization and improvement are required in terms of materials, structures, management systems, etc. Summary of the Invention [Problem to be solved by the invention]

[0005] Based on the above situation, the related art discloses that by providing a carbon material layer inside the battery, side reactions inside the battery can be reduced, the conductive ability can be improved, and ultimately the internal resistance of the battery can be reduced. However, the carbon material layer is prone to falling off, lacks strength, and has gaps between it and the electrode. Meanwhile, the related art also discloses that an electrode layer with good affinity or conductive ability can be fabricated and obtained. However, this cannot be fabricated without a special process, and the process and material requirements are high, so mass production is not possible. [Means for solving the problem]

[0006] In a first aspect, the present embodiment comprises: a battery case; and a battery core module located inside the battery case and including a negative electrode, a negative electrode modifying film, a separator, and a positive electrode that are sequentially stacked; A concave groove is provided on the surface of the negative electrode that is closer to the negative electrode modifying film, and the negative electrode modifying film is tightly embedded in the concave groove, thereby providing a lithium primary button battery.

[0007] In a second aspect, the present embodiment comprises: pressing the negative electrode modified film into a negative electrode having a concave groove on its surface to form a precursor material; the precursor material, the separator, and the positive electrode are sequentially stacked to obtain a battery core module; and sealing the battery core module and the battery case to obtain the lithium primary button battery. A method of making a lithium primary button battery according to the first aspect is provided.

[0008] In a third aspect, an embodiment of the present application provides an electronic device comprising the lithium primary button battery according to the first aspect. [Effects of the Invention]

[0009] This application provides a lithium primary button battery, which first provides a concave groove on the surface of the negative electrode, allowing the negative electrode modifying film to be tightly embedded in the concave groove and achieving the following effects: (1) improves the coating density, coating flatness, and centering between the negative electrode modifying film and the negative electrode, not only ensuring the structural stability of the battery core module itself, but also improving the structural stability in reliability tests of the battery core module, for example, no misalignment occurs between the negative electrode and the negative electrode modifying film during long-term vibration, drop, or centrifugal tests at room temperature or high temperature, thereby enhancing the adhesion stability between the negative electrode modifying film and the negative electrode at high discharge depths and ensuring stable performance during high-current discharge or pulse discharge at room temperature and cryogenic temperatures; and (2) reserves a storage space inside the negative electrode to accommodate the negative electrode modifying film, not only ensuring that the negative electrode modifying film is not deformed during the pressing process, but also improving the flatness of the composite surface of the entire negative electrode material.

[0010] Next, the negative electrode modifying film according to the present invention has the following advantages. [1] The anode modified membrane has a porous structure. Meanwhile, batteries are affected by the potential during the reaction process, causing the positive electrode active material to react with some trace components in the non-aqueous electrolyte to form free cations or anions. Furthermore, because the separator in a battery has a stronger liquid absorption capacity than the positive electrode active material, a concentration polarization effect exists. The eluted positive electrode active material ions shuttle through the separator and potentially undergo irreversible side reactions with the anode, forming a reaction interface with high internal resistance. The anode modified membrane according to the present application has abundant mesopores and micropores, providing strong ion adsorption capabilities, effectively adsorbing eluted positive electrode active ions into the pore structure and ultimately preventing them from migrating to the surface of the anode and causing side reactions. On the other hand, some components in the non-aqueous electrolyte also react with the negative electrode to form an SEI film, which is easily destroyed in the early stages of the battery cycle. Furthermore, as the negative electrode continues to wear out in the later stages of the cycle, the interfacial impedance between it and the separator and positive electrode increases. At this time, if the negative electrode comes into contact with excessive free electrolyte, a high-impedance interfacial film is more likely to form, inhibiting ion transport. The porous structure of the negative electrode modified membrane of the present application has strong adsorption properties, so that free electrolyte can be adsorbed into the modified membrane at the end of discharge, reducing its contact with the negative electrode and improving the discharge performance of the battery. At the same time, the pore structure of the negative electrode modified membrane can be freely adjusted and controlled based on the selection of membrane raw materials and processing process. [2] The anode modified film is a multifunctional layer. The modified film has good electrical conductivity and can form a capacitor-like structure with the positive electrode layer, thereby achieving certain capacitor characteristics. When the battery is in a relatively low-temperature environment, the capacitor structure can provide a certain amount of charge in the instant of reaction. At the same time, good contact is achieved between the modified film and the negative electrode, forming a certain affinity between the particles. When the original passive layer state changes and electrons are conducted, lithium ions can easily pass through the passive layer, thereby ensuring that ions can pass through the passive layer, shortening ion conduction and increasing the instantaneous recovery voltage. At the same time, the modified film can increase the ion and electron conduction rate during the battery discharge process and ensuring the battery's high current output capability. Furthermore, the anode modified film of the present application has good affinity with the negative electrode and can modify the passive layer on the surface of the negative electrode, better protecting the negative electrode from erosion by dissolved positive ions. [3] The anode modified membrane has high strength and good flexibility, and the tensile strength of the anode sheet obtained by the process is as high as 0.4 to 0.5 kN / m, which can ensure the integrity of the anode modified membrane during the electrode sheet separation process, the workability during the battery assembly process, and the integrity of the battery during sealing. At the same time, its good flexibility reduces the stress generated between the anode and the anode when they are coated, preventing uneven adhesion and uneven adhesion surfaces. It also does not dissolve or deform even when infiltrated with a non-aqueous electrolyte or after deep discharge. [4] The negative electrode modified film has high flatness, and the deviation of the thickness range of the negative electrode modified film is only within 3 μm, which reduces the process difficulty when the negative electrode modified film is fitted to the surface of the negative electrode, ensures the flatness of the adhesion between the negative electrode modified film and the negative electrode, reduces the gap between the negative electrode modified film and the negative electrode, and ultimately improves the interfacial contact performance between the two. [5] The anode modified membrane is a self-supporting, integrated functional membrane that not only reduces the interfacial resistance of ion conduction, but also avoids side reactions between the battery system and other substrates that may result from the introduction of other substrates, or a lack of effective space in the battery core module. Furthermore, the processing process for the anode modified membrane of this application is simple, its thickness is not affected by the thickness of the substrate layer, and the overall thickness can be as low as 30 μm. The uniformity of the anode modified membrane is not affected by the material or flatness of the substrate layer. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a structural schematic diagram of a lithium primary button battery according to the present application, in which the positive electrode is directly fabricated by pressing into a sheet. [Figure 2] 1 is a structural schematic diagram of a lithium primary button battery according to the present application, in which the positive electrode is prepared by pressing a current collecting ring onto the surface of a positive electrode active material layer. [Figure 3] 1 is a cross-sectional exploded schematic view of a lithium primary button battery according to the present application. FIG. [Figure 4] FIG. 4 is a partially enlarged view of the circled portion in FIG. 3. [Figure 5] FIG. 1 is a schematic diagram illustrating the assembly of precursor materials in a lithium primary button battery according to the present application. [Figure 6] 1 is a flowchart of a method for fabricating a lithium primary button battery according to the present application. DETAILED DESCRIPTION OF THE INVENTION

[0012] As shown in FIGS. 1 to 4 , the present application provides a lithium primary button battery for use in an electronic device, comprising a battery case 10 and a battery core module located inside the battery case 10, wherein the battery core module comprises a negative electrode 3, a negative electrode modifying film 4, separators 5 and 6, and a positive electrode 7, which are sequentially stacked, and a concave groove 9 is formed on the surface of the negative electrode 3 closest to the negative electrode modifying film 4, and the negative electrode modifying film 4 is tightly embedded in the concave groove 9.

[0013] The shape of the concave groove 9 may be any one or a combination of at least two of a circle, an annulus, or a regular polygon, and may be, for example, a circle. Examples of the regular polygon include a square, a regular pentagon, and a regular hexagon. The center of the concave groove 9 coincides with the center of a vertical projection of the negative electrode modifying film 4. The area ratio of the negative electrode modifying film 4 to the concave groove 9 is 1:1.

[0014] The area ratio of the negative electrode modifying film 4 to the negative electrode 3 is (0.2 to 0.99):1, and may be (0.3 to 0.6):1, for example, 0.2:1, 0.22:1, 0.25:1, 0.28:1, 0.3:1, 0.32:1, 0.35:1, 0.38:1, 0.4:1, 0.42:1, 0.45:1, 0.48:1, 0.5:1, 0.52:1, 0.55:1, 0.58:1, 0.6 :1, 0.65:1, 0.7:1, 0.75:1, 0.78:1, 0.8:1, 0.82:1, 0.85:1, 0.88:1, 0.9:1, 0.925:1, 0.93:1, 0.935:1, 0.94:1, 0.945:1, 0.95:1, 0.955:1, 0.96:1, 0.965:1, 0.97:1, 0.975:1, 0.98:1, 0.985:1, 0.99:1, and the like.

[0015] The functionality of the anode modifying film can be fully exerted by adjusting and controlling the area ratio between the anode modifying film and the anode. If the area ratio is too low, the functionality of the anode modifying film will be weakened due to a decrease in the area of ​​the modified region. For example, the improvement in the electrical conductivity of the conductive surface will be relatively small, resulting in a decrease in the adsorption area and a decrease in the adsorption ability for eluted positive electrode active ions. Conversely, the distance between the edges of the concave surface will be small, making it difficult to properly caulk and fix the anode modifying film. Furthermore, if the area is too large, even if the functionality is not significantly improved, the manufacturing process costs will increase.

[0016] The ratio of the depth of the concave groove 9 to the thickness of the negative electrode modifying film 4 is (0.3 to 1.3):1, and may be (0.95 to 1.05):1, for example, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.90:1, 0.91:1, 0.92:1, 0.93:1, 0.94:1, It may be 0.95:1, 0.96:1, 0.97:1, 1:1, 1.02:1, 1.03:1, 1.04:1, 1.05:1, 1.06:1, 1.07:1, 1.08:1, 1.1:1, 1.12:1, 1.15:1, 1.18:1, 1.2:1, 1.22:1, 1.25:1, 1.28:1, 1.3:1, etc.

[0017] By adjusting and controlling the ratio between the depth of the concave groove and the thickness of the negative electrode modifying film, the negative electrode modifying film and the surface of the negative electrode are completely flush with each other and have good physical bonding strength. If the depth of the concave groove is too deep, the upper surface of the negative electrode modifying film is not pressed down to a sufficient degree during the leveling process, resulting in an insufficient bonding strength between the lower surface of the negative electrode modifying film and the negative electrode in the concave groove, unevenness, and insufficient exhaust, resulting in a certain air gap surface. If the depth of the concave groove is too shallow and the thickness of the negative electrode modifying film is too large, the negative electrode modifying film is too thick during the leveling process, resulting in insufficient space in the concave groove, causing the negative electrode modifying film to stretch laterally during leveling and pressing down, further exposing the surface of the negative electrode and resulting in an uneven surface. In addition, the sizes of the negative electrode and the negative electrode modifying film exceed the height limit, affecting the overall size of the battery core.

[0018] The thickness of the negative electrode modifying film 4 is 0.03 mm to 0.20 mm, and may be 0.05 to 0.10 mm, for example, 0.03 mm, 0.04 mm, 0.05 mm, 0.06 mm, 0.07 mm, 0.08 mm, 0.09 mm, 0.10 mm, 0.11 mm, 0.12 mm, 0.13 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm, 0.20 mm, etc.

[0019] By adjusting and controlling the thickness of the negative electrode modified film, the functionality of the negative electrode modified film can be satisfied, and the assemblability and sufficient capacity design of the entire battery core can be ensured. If the thickness is too small, the processing of the negative electrode modified film becomes more difficult, the production costs increase, and the assembly processing of the negative electrode modified film during the assembly process becomes more difficult. On the other hand, if the thickness is too thin, the adsorption ability for eluted positive electrode active ions decreases accordingly. Conversely, if the thickness is too thick, the structural design space of the negative electrode is occupied, and the design capacity of the entire battery core is reduced.

[0020] The tensile strength of the negative electrode modifying film 4 is 0.1 to 2 KN / m, and may be 0.4 to 0.5 KN / m, for example, 0.1 KN / m, 0.2 KN / m, 0.3 KN / m, 0.4 KN / m, 0.42 KN / m, 0.45 KN / m, 0.48 KN / m, 0.5 KN / m, 0.8 KN / m, 1 KN / m, 1.2 KN / m, 1.5 KN / m, 1.8 KN / m, 2 KN / m, etc.

[0021] By adjusting and controlling the tensile strength of the negative electrode modified film, the negative electrode modified film has excellent machining performance, including the performance of cutting, transferring, positioning, and leveling. If the tensile strength is too low, it will affect the implementation of the entire processing process and the consistency of the assembly. Furthermore, because the negative electrode modified film has poor strength or is easily damaged, the adhesion of the negative electrode modified film will decrease with increasing depth of discharge. Conversely, if the film pieces are too large, it will further affect some of the functionality of the negative electrode modified film, such as reducing its conductivity and its ability to adsorb eluted positive electrode active ions. Methods for increasing the tensile strength of the negative electrode modified film include increasing the content of binder, which will reduce the content of conductive components and similarly reduce the porosity of the negative electrode modified film.

[0022] The surface density of the negative electrode modifying film 4 is 40 to 80 g / cm 2 Of which, 50-60g / cm 2 For example, 40 g / cm 2 , 45g / cm 2 , 50g / cm 2 , 52g / cm 2 , 55g / cm2 , 58g / cm 2 , 60g / cm 2 , 65g / cm 2 , 70g / cm 2 , 75g / cm 2 , 80g / cm 2 etc. may also be used.

[0023] By adjusting and controlling the surface density of the negative electrode modified film, the negative electrode modified film has excellent comprehensive functionality, but if the surface density is too low, it will exhibit poor film strength, and as the reaction of the battery core progresses toward the end of discharge, the functionality of the negative electrode modified film will deteriorate rapidly. Conversely, it will indicate a corresponding decrease in the porosity of the negative electrode modified film, which will reduce its ability to adsorb dissolved positive electrode active ions. Similarly, it will indicate that the negative electrode modified film contains a high content of non-conductive binder components, which will result in a corresponding decrease in the conductivity of the negative electrode modified film.

[0024] The pore volume of the negative electrode modifying membrane 4 is 0.05 to 0.5 cm 3 / g, of which 0.15 to 0.33 cm 3 / g, for example, 0.05 cm 3 / g, 0.08cm 3 / g, 0.1cm 3 / g, 0.12cm 3 / g, 0.15cm 3 / g, 0.18cm 3 / g, 0.2cm 3 / g, 0.22cm 3 / g, 0.25cm 3 / g, 0.28cm 3 / g, 0.3cm 3 / g, 0.33cm 3 / g, 0.35cm 3 / g, 0.4cm 3 / g, 0.45cm 3 / g, 0.5cm 3 / g, etc.

[0025] By adjusting and controlling the pore volume of the negative electrode modified membrane, the functionality of the modified membrane can be fully exerted. The pore volume of the modified membrane is also affected by the material model, the compounding ratio of each component, and the processing method. If the pore volume is too small, the adsorption capacity for the eluted positive electrode active ions will be reduced, mainly due to the amount of adsorption being too small and quickly reaching saturation, and conversely, the adsorption efficiency for the eluted positive electrode active ions will be low.

[0026] The material of the negative electrode modifying film 4 includes an active material. The active material includes at least one of an oxide material, a carbon material, metal conductive particles, or fluorine-containing particles, for example, an oxide material and / or a carbon material. The oxide material includes any one or a combination of at least two of titanium dioxide, molybdenum dioxide, aluminum oxide, lithium titanate, or silver oxide. The carbon material includes any one or a combination of at least two of graphene, acetylene black, carbon nanotubes, activated carbon, or graphite. The metal conductive particles include any one or a combination of at least two of copper particles, silver particles, or gold particles. The fluorine-containing particles include any one or a combination of at least two of lithium fluoride, fluorocarbon, polytetrafluoroethylene, polyvinylidene fluoride, or polyvinyl fluoride copolymer.

[0027] The material of the negative electrode modifying film 4 further contains a binder, which contains at least one of polytetrafluoroethylene, polyvinylidene fluoride, fluorinated ethylene propylene copolymer, and polyacrylic acid.

[0028] The mass ratio of the active material to the binder is 1:(0.03-0.3), which may be 1:(0.05-0.25), for example, 1:0.03, 1:0.05, 1:0.08, 1:0.1, 1:0.12, 1:0.15, 1:0.18, 1:0.2, 1:0.22, 1:0.25, 1:0.28, 1:0.3, etc.

[0029] By adjusting and controlling the mass ratio of the active material to the binder, the negative electrode modified membrane has excellent functionality, including, for example, electrical conductivity, adsorption, and flexible self-supporting ability. If the mass ratio is too low, the negative electrode modified membrane cannot be self-supported or has poor membrane strength; conversely, it has poor electrical conductivity and low positive electrode active ion adsorption capacity, and the proportion of other materials is low.

[0030] In the method for preparing the negative electrode modifying membrane, the active material and the binder are molded or extruded. The method may be prepared without using a solvent during the molding process, or may be prepared using a certain inorganic or organic solvent, depending on the process needs.

[0031] The separator includes a glass fiber separator 5 and / or a polypropylene separator 6. The separator has 1 to 3 layers, and may have 2 layers, for example, 1 layer, 2 layers, or 3 layers, and the separator includes a combination of the glass fiber separator 5 and the polypropylene separator 6.

[0032] The glass fiber separator 5 is located closer to the anode 3, while the polypropylene separator 6 is located closer to the cathode 7, thereby achieving a functional match with the anode modified membrane 4. The reasons for this are (1) the glass fiber separator's lower stiffness than the polypropylene separator, favoring adhesion between the glass fiber separator and the anode modified membrane; and (2) the glass fiber separator's liquid absorption capacity, which is such that the glass fiber separator's liquid absorption capacity > that of the anode modified membrane > that of the polypropylene separator > that of the cathode, creates a concentration gradient. The placement of the glass fiber separator is beneficial for ensuring uniform electrolyte distribution throughout the battery core. At the same time, the glass fiber separator acts as an electrolyte storage interface, ensuring the amount of free electrolyte at the end of the battery core's life, enhancing ion conduction capabilities, and ensuring the battery core's shock resistance at extremely low temperatures. In addition, the amount of free electrolyte stored at the positive electrode interface can be reduced, the leaching of the positive electrode active material and the amount of free electrolyte stored in the negative electrode modifying film can be reduced, and side reactions between the leached positive electrode active ions and the negative electrode can be reduced.

[0033] The battery case 10 includes an anode bottom cover 2 located on the anode 3 side and a cathode cover 8 located on the cathode 7 side. A gasket 1 is provided on the anode bottom cover 2, and the gasket 1 is provided at the edge engagement portion between the anode bottom cover 2 and the cathode cover 8.

[0034] The lithium primary button cell further comprises an electrolyte.

[0035] As shown in FIG. 6 , the present application further provides a method for fabricating a lithium primary button battery, the method comprising: Step S101: pressing the negative electrode modifying film into a negative electrode having a concave groove on its surface to form a precursor material; Step S102: sequentially stacking the precursor material, the separator, and the positive electrode to obtain a battery core module; and step S103 of sealing the battery core module and the battery case to obtain the lithium primary button battery.

[0036] After pressing the anode modifying film into the anode having a concave groove on its surface, the method further includes leveling the contact surface between the anode modifying film and the concave groove, thereby fully ensuring the degree of contact and flatness of the contact between them.

[0037] After cutting the negative electrode modifying film into a predetermined shape, it is pressed into the negative electrode having a concave groove on its surface. The positioning requires that the center of its vertical projection completely overlaps with the center of the concave groove in the negative electrode, achieving a flat and tight fit at the initial stage.

[0038] If the depth of the concave groove is less than or equal to the thickness of the negative electrode modified film, the negative electrode modified film will be initially pressured during the leveling process, and the center of the projection surfaces of the two will be subjected to force. Through the conduction of the force, the lower surface of the negative electrode modified film will be embedded into and tightly fitted to the upper surface of the concave groove of the negative electrode, while the air between them will be expelled at the same time, achieving a completely flat and tight fit effect. If the depth of the concave groove is greater than the thickness of the negative electrode modified film, it is equivalent to the negative electrode modified film being placed within the concave groove of the negative electrode. During the leveling process, the portion of the negative electrode that is not within the concave groove will be initially subjected to force, and the central portion of the concave groove will be in a pressure-deficient or pressure-deficient state. Due to the continuous action of the pressing force, the negative electrode will be deformed under pressure, acting on the central pressure-deficient area. As a result, the negative electrode modified film will be tightly fitted into the concave groove, and the upper surface will be gathered in and fitted by the negative electrode, thereby achieving a completely flat and tight fit effect.

[0039] The battery case includes an anode bottom cover 2 located on the anode 3 side and a cathode lid 8 located on the cathode 7 side. A gasket 1 is provided on the anode bottom cover 2, and the gasket 1 is provided at the edge engagement portion between the anode bottom cover 2 and the cathode lid 8.

[0040] The precursor material and the separators 5, 6 are pressed into the negative electrode bottom cap.

[0041] The separators 5 and 6 are in an inverted U shape, and both sides of the inverted U shape are curved toward the positive electrode 7 .

[0042] After the above-mentioned sequential lamination and provision, a step of injecting an electrolyte solution is further included.

[0043] After injecting the electrolyte, the formed positive electrode sheet is placed, and finally the positive electrode cover 8 is placed on the battery, and the battery is subjected to a primary sealing press and a secondary sealing press to complete a lithium primary button battery.

[0044] The positive electrode sheet includes a current collector and a positive electrode active material layer provided on at least one side of the current collector. The positive electrode active material layer includes a positive electrode active material, a conductive agent, and a binder. The positive electrode active material may, for example, include manganese dioxide, carbon fluoride, or iron sulfide. The conductive agent may, for example, include at least one of graphite, carbon nanotubes, conductive carbon black, or graphene. The binder may, for example, include at least one of polytetrafluoroethylene, polyvinylidene fluoride, sodium polyacrylate, polyethylene oxide, or polyacrylonitrile.

[0045] The positive electrode sheet forming process includes uniformly mixing a positive electrode active material, a conductive agent, and a binder using a high-speed mixer, and then pressing the mixture into a sheet using a molding machine for direct use. A current collecting mesh may be pressed onto the surface of the positive electrode active material layer, or a current collecting ring may be used in combination.

[0046] The material of the negative electrode 3 includes, for example, lithium metal or a lithium alloy.

[0047] The lithium primary button battery in the following examples and comparative examples is a CR2032 type button battery with a diameter of 20 mm and a thickness of 3.2 mm, of which the positive electrode sheet is 15.00 mm in diameter and 1.85 mm in thickness, the negative electrode sheet is 16.00 mm in diameter and 0.58 mm in thickness, and the electrolyte is a non-aqueous lithium perchlorate electrolyte with a concentration of 0.9 mol / L (the solvent is propylene carbonate and ethylene glycol dimethyl ether).

[0048] The method for producing the positive electrode sheet is as follows: manganese dioxide, conductive carbon black, and polytetrafluoroethylene emulsion are uniformly mixed in a mass ratio of 1:0.5:0.6 by a high-speed mixer, and then dried to obtain a powder material, which is then pressed into a positive electrode sheet by a powder material molding ring assembly integrated machine to assemble a current collector, thereby obtaining the positive electrode sheet as shown in FIG. 1; Alternatively, the method may include a step of uniformly mixing manganese dioxide, conductive carbon black, and polytetrafluoroethylene emulsion in a mass ratio of 1:0.5:0.6 using a high-speed mixer, followed by drying to obtain a powder material, and then pressing a current collecting ring onto the surface of the positive electrode using a molding machine to obtain the positive electrode sheet as shown in FIG. 2.

[0049] The above description of the button battery is intended to fully describe the technical solution of the present application, and should not be considered as limiting the present application.

[0050] Example 1 This embodiment provides a lithium primary button battery. As shown in FIGS. 3 and 4, the lithium primary button battery includes a battery case 10, a battery core module and an electrolyte located inside the battery case 10. The battery core module includes a lithium metal anode 3, a circular flat anode modifying film 4, a separator, and a manganese dioxide positive electrode 7, which are sequentially stacked. The lithium metal anode 3 has a circular concave groove 9 on the surface closest to the circular flat anode modifying film 4, and the circular flat anode modifying film 4 is tightly fitted within the circular concave groove 9. The battery case 10 includes an anode bottom cover 2 located on the lithium metal anode 3 side and a cathode bottom cover 8 located on the manganese dioxide cathode 7 side, and a gasket 1 is provided on the anode bottom cover 2, and the gasket 1 is provided at the edge attachment location of the anode bottom cover 2 and the cathode bottom cover 8. The separator includes a combination of a glass fiber separator 5 and a polypropylene separator 6, and the glass fiber separator 5 is provided on the side closer to the lithium metal anode 3, and the polypropylene separator 6 is provided on the side closer to the manganese dioxide cathode 7.

[0051] The area ratio of the circular flat anode modifying film 4 to the circular concave grooves 9 is 1:1, the area ratio of the circular flat anode modifying film 4 to the lithium metal anode 3 is 0.45:1, and the ratio of the depth of the circular concave grooves 9 to the thickness of the circular flat anode modifying film 4 is 0.95:1. The circular flat anode modifying film 4 has a thickness of 0.08 mm, a tensile strength of 0.45 KN / m, and an areal density of 55 g / cm. 2 The pore diameter is 2 to 200 nm and the pore volume is 0.3 cm3 / g. The circular, flat negative electrode modifying film 4 is produced by molding a material containing a carbon material and a polytetrafluoroethylene binder in a mass ratio of 1:0.15.

[0052] This embodiment further provides a method for fabricating the above-mentioned lithium primary button battery, which includes: As shown in FIG. 5, a circular upper mold is used on the negative electrode bottom cover side to press the surface of the lithium metal negative electrode to form a circular concave groove, and then a circular flat negative electrode modifying film is pressed into the negative electrode with the circular concave groove on its surface. The positioning requires that the center of its vertical projection completely overlaps the center of the circular concave groove in the negative electrode. After leveling with a press tool, a precursor material is formed, and then a separator is pressed into the negative electrode bottom cover to form a "U" shape. A non-aqueous electrolyte is injected, and then a molded manganese dioxide positive electrode sheet is placed inside. Finally, a positive electrode cover is attached, and primary and secondary sealing presses are sequentially performed to obtain the lithium primary button battery.

[0053] Example 2 This example differs from Example 1 in the following respects: the shape of the negative electrode modifying film is a circular flat surface, the shape of the concave groove is a circular surface, the area ratio of the circular flat surface of the negative electrode modifying film to the circular concave groove 9 is 1:1, the area ratio of the circular flat surface of the negative electrode modifying film to the negative electrode is 0.3:1, and the ratio of the depth of the circular concave groove 9 to the thickness of the circular flat surface of the negative electrode modifying film is 0.95:1.

[0054] The circular flat negative electrode coating has a thickness of 0.05 mm, a tensile strength of 0.4 KN / m, and an areal density of 50 g / cm 2 The pore diameter is 2 to 200 nm and the pore volume is 0.3 cm 3 / g. The annular flat negative electrode modifying film 4 was produced by molding a material containing a carbon material and a polytetrafluoroethylene binder in a mass ratio of 1:0.1, and all other points were the same as in Example 1.

[0055] Example 3 This example differs from Example 1 in the following respects: the shape of the negative electrode modifying film is a square plane, the shape of the concave groove is square, the area ratio of the square plane negative electrode modifying film to the square concave groove is 1:1, the area ratio of the square plane negative electrode modifying film to the negative electrode is 0.6:1, and the ratio of the depth of the square concave groove to the thickness of the square plane negative electrode modifying film is 0.97:1.

[0056] The square planar negative electrode modified film has a thickness of 0.10 mm, a tensile strength of 0.5 KN / m, and an areal density of 60 g / cm 2 The pore diameter is 2 to 200 nm and the pore volume is 0.3 cm 3 The square-plane negative electrode modifying film was produced by molding a material containing a carbon material and a polytetrafluoroethylene binder in a mass ratio of 1:0.2, and all other aspects were the same as in Example 1.

[0057] Example 4 This embodiment differs from Example 1 in that the separator is replaced with a double polypropylene separator, but is otherwise the same as Example 1.

[0058] Example 5 This example differs from Example 1 in that the area ratio between the circular flat negative electrode modifying film and the negative electrode is 0.1:1, but all other points are the same as Example 1.

[0059] Example 6 This example differs from Example 1 in that the area ratio of the circular flat negative electrode modifying film to the negative electrode is 1.2:1, but all other points are the same as Example 1.

[0060] Example 7 This example differs from Example 1 in that the ratio of the depth of the circular concave groove to the thickness of the circular flat surface of the negative electrode modifying film is 0.1:1, but all other points are the same as Example 1.

[0061] Example 8 This example differs from Example 1 in that the ratio of the depth of the circular concave groove to the thickness of the circular flat surface of the negative electrode modifying film is 2:1, but all other points are the same as Example 1.

[0062] Example 9 In this example, the surface density of the circular flat negative electrode modifying film is 30 g / cm 2 This is different from the first embodiment in that the above point is true, and all other points are the same as those of the first embodiment.

[0063] Example 10 In this example, the surface density of the circular flat negative electrode modifying film is 90 g / cm 2 This is different from the first embodiment in that the above point is true, and all other points are the same as those of the first embodiment.

[0064] Example 11 In this example, the pore volume of the circular flat negative electrode modified membrane is 0.02 cm 3 / g, and all other points are the same as in Example 1.

[0065] Example 12 In this example, the pore volume of the circular flat negative electrode modified membrane is 0.7 cm 3 / g, and all other points are the same as in Example 1.

[0066] Example 13 This example differs from Example 1 in that the mass ratio of the active material of carbon material to the binder of polytetrafluoroethylene is 1:0.02, but all other points are the same as Example 1.

[0067] Example 14 This example differs from Example 1 in that the mass ratio of the active material of carbon material to the binder of polytetrafluoroethylene is 1:0.4, but all other points are the same as Example 1.

[0068] (Comparative Example 1) This comparative example differs from Example 1 in that the negative electrode is made flat by direct pressing and no circular flat negative electrode modifying film is provided, but all other points are the same as Example 1.

[0069] (Comparative Example 2) This comparative example differs from Example 1 in that the negative electrode is directly pressed to a flat surface, a circular flat negative electrode modifying film is not provided, and the separator is replaced with a double polypropylene separator; all other aspects are the same as Example 1.

[0070] (Comparative Example 3) This comparative example differs from Example 1 in that the negative electrode is directly pressed to have a flat surface and a circular flat negative electrode modifying film is provided, but all other points are the same as Example 1.

[0071] Comparative Example 4 This comparative example differs from Example 1 in that the negative electrode is directly pressed to a flat surface, a circular flat negative electrode modifying film is provided, and the separator is replaced with a double polypropylene separator; all other aspects are the same as Example 1.

[0072] (Comparative Example 5) This comparative example differs from Example 1 in that the negative electrode is directly pressed to form a flat surface, and the circular flat negative electrode modifying film is replaced with a circular carbon material layer produced by uniformly stirring acetylene black with ethanol and polyacrylic acid to form a slurry, transferring and applying the slurry to a polypropylene nonwoven fabric, vacuum baking, and then cutting the fabric into a circular flat surface. All other aspects are the same as those of Example 1.

[0073] (Comparative Example 6) This comparative example differs from Example 1 in that the negative electrode is directly pressed to form a flat surface, the circular flat negative electrode modification film is replaced with a circular carbon material layer prepared by uniformly stirring acetylene black with ethanol and polyacrylic acid to form a slurry, transferring and applying the slurry to a polypropylene nonwoven fabric, vacuum baking, and then cutting into a circular flat surface, and the separator is replaced with a double polypropylene separator. All other aspects are the same as Example 1.

[0074] (Comparative Example 7) This comparative example differs from Example 1 in that the negative electrode is directly pressed to form a flat surface, and the circular flat negative electrode modification film is replaced with a circular carbon foil composite layer produced by uniformly stirring acetylene black with ethanol and polyacrylic acid to form a slurry, which is then transferred and applied to a steel mesh and a polypropylene nonwoven fabric, vacuum baked, rolled flat, and then cut into a circular flat surface. All other aspects are the same as Example 1.

[0075] (Comparative Example 8) In this comparative example, the negative electrode is directly pressed to form a flat surface, and the circular flat negative electrode modification film is replaced with a circular carbon foil composite layer prepared by uniformly stirring acetylene black with ethanol and polyacrylic acid to form a slurry, which is then transferred and applied to a steel mesh and a polypropylene nonwoven fabric, vacuum baked, rolled flat, and then cut into a circular flat surface. The separator is replaced with a double polypropylene separator, which is different from Example 1, except for the other points.

[0076] (Test conditions) The performance tests were carried out on the negative electrode modifying film 4 or the carbon foil composite layer according to Examples 1 to 14 and Comparative Examples 1 to 8, and the test methods were as follows: For tensile strength, a tensile strength test was performed on a membrane piece using an electronic separator tensile tester. First, a 100 x 14 mm negative electrode modified membrane 4 was cut and placed between the upper and lower chucks of the tensile tester. The clamping distance was 50 mm and the preliminary test force was 0.5 N. The instrument was then started and the sample was pulled at a constant elongation rate of 10 mm / min until it broke, and the maximum tensile force value during the pulling process was recorded.

[0077] Tests were conducted on the lithium primary button batteries according to Examples 1 to 14 and Comparative Examples 1 to 8, and the test methods were as follows: (1) First, a discharge program was performed at room temperature, in which the batteries were discharged at a constant resistance of 0.2 mA for 800 hours. Then, the batteries were placed in refrigerators at -30°C and -20°C for 4 hours. (2) The background current is 10 μA, and then the battery is pulse-discharged at a constant current of 10 mA for 0.5 seconds, and left for 4.5 seconds. This process is repeated three times, and the discharge voltage value is recorded. Then, the refrigerator temperature is adjusted to -20°C and the battery is left there for 4 hours, and the above test process is repeated three times. Five batteries of each type are tested, and the average value is taken. The formula for calculating the voltage deviation of the five tested batteries is: Voltage deviation = (maximum voltage - minimum voltage) / average voltage.

[0078] The test results are shown in Tables 1 and 2.

[0079] [Table 1]

[0080] [Table 2]

[0081] As can be seen from Tables 1 and 2, the tensile strength value of the anode modified membrane 4 is positively correlated with the thickness of the anode modified membrane and with the polytetrafluoroethylene content, and the pore volume and areal density parameters of the anode modified membrane 4 also affect its tensile strength value. As can be seen from a comparison between Examples 1 and 4, by providing the glass fiber separator 5 on the side closer to the anode 3 and the polypropylene separator 6 on the side closer to the cathode 7, it is possible to achieve a match in functionality of the anode modified membrane 4.

[0082] As can be seen from the comparison between Example 1 and Examples 5 and 6, the present invention can fully exhibit their functionality by adjusting and controlling the area ratio between the circular flat negative electrode modifying film and the negative electrode.

[0083] As can be seen from a comparison between Examples 1 and 7 to 8, the present invention adjusts and controls the ratio between the depth of the circular concave groove and the thickness of the circular flat negative electrode modifying film, so that the negative electrode modifying film and the negative electrode surface are completely flush with each other and have a certain good physical bonding strength.

[0084] As can be seen from the comparison between Example 1 and Examples 9 and 10, the present invention adjusts and controls the surface density of the circular flat negative electrode modifying film, so that the negative electrode modifying film has excellent comprehensive functionality.

[0085] As can be seen from a comparison between Example 1 and Examples 11 and 12, the present invention allows the functionality of the modified membrane to be fully exhibited by adjusting and controlling the pore volume of the circular flat negative electrode modified membrane.

[0086] As can be seen from the comparison between Examples 1 and 13 to 14, the present invention provides an anode-modified membrane with excellent functionality, including, for example, electrical conductivity, adsorptivity, and flexible self-supporting properties, by adjusting and controlling the mass ratio of the active material to the binder.

[0087] As can be seen from a comparison between Example 1 and Comparative Examples 1 to 4, the absence of the concave groove 9 on the surface of the negative electrode 3 closest to the negative electrode modifying film 4 weakens the bonding strength between the negative electrode 3 and the negative electrode modifying film 4, raising the risk of detachment. Because of the good coating tightness between the negative electrode modifying film and the negative electrode according to the present application, the lithium primary button battery exhibits good consistency in pulse voltage when subjected to a pulse test at low temperature after a certain depth of discharge.

[0088] As can be seen from the comparison between Example 1 and Comparative Examples 5 to 8, even if a circular carbon material layer or a circular carbon foil composite layer disclosed in the related art is adopted, it is not possible to achieve all of the technical effects of the anode modifying film of the present application.

[0089] This application provides a lithium primary button battery, which first provides a concave groove on the surface of the negative electrode, allowing the negative electrode modifying film to be tightly embedded in the concave groove and achieving the following effects: (1) improves the coating density, coating flatness, and centering between the negative electrode modifying film and the negative electrode, not only ensuring the structural stability of the battery core module itself, but also improving the structural stability in reliability tests of the battery core module, for example, no misalignment occurs between the negative electrode and the negative electrode modifying film during long-term vibration, drop, or centrifugal tests at room temperature or high temperature, thereby enhancing the adhesion stability between the negative electrode modifying film and the negative electrode at high discharge depths and ensuring stable performance during high-current discharge or pulse discharge at room temperature and cryogenic temperatures; and (2) reserves a storage space inside the negative electrode to accommodate the negative electrode modifying film, not only ensuring that the negative electrode modifying film is not deformed during the pressing process, but also improving the flatness of the composite surface of the entire negative electrode material.

[0090] Next, the negative electrode modifying film according to the present invention has the following advantages. [1] The anode modified membrane has a porous structure. Meanwhile, batteries are affected by the potential during the reaction process, causing the positive electrode active material to react with some trace components in the non-aqueous electrolyte to form free cations or anions. Furthermore, because the separator in a battery has a stronger liquid absorption capacity than the positive electrode active material, a concentration polarization effect exists. The eluted positive electrode active material ions shuttle through the separator and potentially undergo irreversible side reactions with the anode, forming a reaction interface with high internal resistance. The anode modified membrane according to the present application has abundant mesopores and micropores, providing strong ion adsorption capabilities, effectively adsorbing eluted positive electrode active ions into the pore structure and ultimately preventing them from migrating to the surface of the anode and causing side reactions. On the other hand, some components in the non-aqueous electrolyte also react with the negative electrode to form an SEI film, which is easily destroyed in the early stages of the battery cycle. Furthermore, as the negative electrode continues to wear out in the later stages of the cycle, the interfacial impedance between it and the separator and positive electrode increases. At this time, if the negative electrode comes into contact with excessive free electrolyte, a high-impedance interfacial film is more likely to form, inhibiting ion transport. The porous structure of the negative electrode modified membrane of the present application has strong adsorption properties, so that free electrolyte can be adsorbed into the modified membrane at the end of discharge, reducing its contact with the negative electrode and improving the discharge performance of the battery. At the same time, the pore structure of the negative electrode modified membrane can be freely adjusted and controlled based on the selection of membrane raw materials and processing process. [2] The anode modified film is a multifunctional layer. The modified film has good electrical conductivity and can form a capacitor-like structure with the positive electrode layer, thereby achieving certain capacitor characteristics. When the battery is in a relatively low-temperature environment, the capacitor structure can provide a certain amount of charge in the instant of reaction. At the same time, good contact is achieved between the modified film and the negative electrode, forming a certain affinity between the particles. When the original passive layer state changes and electrons are conducted, lithium ions can easily pass through the passive layer, thereby ensuring that ions can pass through the passive layer, shortening ion conduction and increasing the instantaneous recovery voltage. At the same time, the modified film can increase the ion and electron conduction rate during the battery discharge process and ensuring the battery's high current output capability. Furthermore, the anode modified film of the present application has good affinity with the negative electrode and can modify the passive layer on the surface of the negative electrode, better protecting the negative electrode from erosion by dissolved positive ions. [3] The anode modified membrane has high strength and good flexibility, and the tensile strength of the anode sheet obtained by the process is as high as 0.4 to 0.5 kN / m, which can ensure the integrity of the anode modified membrane during the electrode sheet separation process, the workability during the battery assembly process, and the integrity of the battery during sealing. At the same time, its good flexibility reduces the stress generated between the anode and the anode when they are coated, preventing uneven adhesion and uneven adhesion surfaces. It also does not dissolve or deform even when infiltrated with a non-aqueous electrolyte or after deep discharge. [4] The negative electrode modified film has high flatness, and the deviation of the thickness range of the negative electrode modified film is only within 3 μm, which reduces the process difficulty when the negative electrode modified film is fitted to the surface of the negative electrode, ensures the flatness of the adhesion between the negative electrode modified film and the negative electrode, reduces the gap between the negative electrode modified film and the negative electrode, and ultimately improves the interfacial contact performance between the two. [5] The anode modified membrane is a self-supporting, integrated functional membrane that not only reduces the interfacial resistance of ion conduction, but also avoids side reactions between the battery system and other substrates that may result from the introduction of other substrates, or a lack of effective space in the battery core module. Furthermore, the processing process for the anode modified membrane of this application is simple, its thickness is not affected by the thickness of the substrate layer, and the overall thickness can be as low as 30 μm. The uniformity of the anode modified membrane is not affected by the material or flatness of the substrate layer. [Explanation of symbols]

[0091] 1···Gasket, 2···Negative electrode bottom cover, 3···Negative electrode, 4···Negative electrode modified membrane, 5···Glass fiber separator, 6···Polypropylene separator, 7···Positive electrode, 8···Positive electrode cover, 9···Concave groove, 10···Battery case.

Claims

1. a battery case; and a battery core module located inside the battery case and including a negative electrode, a negative electrode modifying film, a separator, and a positive electrode that are sequentially stacked; a concave groove is provided on a surface of the negative electrode that is closer to the negative electrode modifying film, and the negative electrode modifying film is tightly embedded in the concave groove; Lithium primary button cell battery.

2. The shape of the concave groove includes any one or a combination of at least two of a circle, an annulus, or a regular polygon; the center of the concave groove overlaps with the center of a vertical projection of the negative electrode modifying film; 10. The lithium primary button battery of claim 1.

3. the area ratio of the negative electrode modifying film to the concave groove is 1:1; the area ratio of the negative electrode modifying film to the negative electrode is (0.2 to 0.99):1, the ratio of the depth of the concave groove to the thickness of the negative electrode modifying film is (0.3 to 1.3):1; 3. The lithium primary button battery according to claim 1 or 2.

4. The negative electrode modifying film is The thickness is 0.03 mm to 0.20 mm, The tensile strength is 0.1 to 2 KN / m, Surface density is 40 to 80 g / cm 2 and Pore ​​volume is 0.05 to 0.5 cm 3 / g, The lithium primary button battery according to any one of claims 1 to 3.

5. The material of the negative electrode modified membrane includes an active material and a binder; the active material comprises at least one of an oxide material, a carbon material, a metal conductive particle, or a fluorine-containing particle; the binder contains at least one of polytetrafluoroethylene, polyvinylidene fluoride, fluorinated ethylene-propylene copolymer, and polyacrylic acid; The mass ratio of the active material to the binder is 1:(0.03-0.3); The lithium primary button battery according to any one of claims 1 to 4.

6. The separator is a glass fiber separator, or a polypropylene separator, or a combination of a glass fiber separator and a polypropylene separator; The number of layers is 1 to 3. The lithium primary button battery according to any one of claims 1 to 5.

7. the battery case includes a negative electrode bottom cover located on the negative electrode side and provided with a gasket, and a positive electrode cover located on the positive electrode side; the gasket is provided at an edge engagement portion between the negative electrode bottom cover and the positive electrode cover, The lithium primary button battery further comprises an electrolyte; The lithium primary button battery according to any one of claims 1 to 6.

8. pressing the negative electrode modified film into a negative electrode having a concave groove on its surface to form a precursor material; the precursor material, the separator, and the positive electrode are sequentially stacked to obtain a battery core module; and sealing the battery core module and the battery case to obtain the lithium primary button battery. A method for making the lithium primary button battery of any one of claims 1 to 7.

9. After pressing the negative electrode modifying film into the negative electrode having a concave groove on the surface, The method further includes leveling the contact surface between the negative electrode modifying film and the concave groove. The method of claim 8.

10. A lithium primary button battery according to any one of claims 1 to 7, electronic equipment.

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