Lithium supplementing electrode sheet and preparation method therefor, lubricant, battery, and electric device

Abstract

The present application relates to the technical field of batteries, and to a lithium supplementing electrode sheet and a preparation method therefor, a lubricant, a battery, and an electric device. The preparation method for the lithium supplementing electrode sheet comprises: by means of asynchronous rolling, calendaring a lithium material by using a calendaring roller, a lubricant being provided between the lithium material and the calendaring roller; and laminating the calendared lithium material to the surface of an electrode sheet substrate, wherein the lubricant comprises lubricating oil and inorganic particles dispersed in the lubricating oil. In the preparation method for the lithium supplementing electrode sheet of the present application, there are a large number of binding sites between a lithium film layer obtained by calendaring and an active material layer of an electrode sheet substrate, so that the binding force between the lithium film layer and the active material layer can be improved, thus solving the problems in the prior art of difficulty of laminating a lithium film layer to an electrode sheet substrate and a poor binding force between the lithium film layer and the active material layer. The prepared lithium supplementing electrode sheet has good wettability in an electrolyte, and the battery prepared using the lithium supplementing electrode sheet has good cycle performance and good low-temperature resistance.

Description

Lithium-replenishing electrode and preparation method thereof, lubricant, battery and electrical equipment

[0001] Cross-references

[0002] This application claims priority to the Chinese invention patent application with application number 202311628247.3 filed on November 29, 2023, and invention name “Lithium-replenishing electrode and preparation method thereof, lubricant, battery and electrical equipment”, the contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the field of battery technology, and in particular to a lithium-supplementing electrode and a preparation method thereof, a lubricant, a battery, and an electrical device. Background Art

[0004] The lithium film layer is laminated with the electrode substrate to form a lithium-supplemented electrode to improve the initial efficiency and cycle performance of the battery. When the lithium film layer is laminated with the active material layer of the electrode substrate, the bonding strength between the lithium film layer and the active material layer of the electrode substrate is poor, making lamination more difficult.

[0005] Summary of the Invention

[0006] In response to the shortcomings of the existing technology, the present application provides a lithium-replenishing electrode and its preparation method, lubricant, battery and electrical equipment to solve the problems of difficult lamination of the lithium film layer and the electrode substrate and poor bonding between the lithium film layer and the active material layer of the electrode substrate, and can improve the wettability of the prepared lithium-replenishing electrode to the electrolyte.

[0007] In a first aspect, the present application provides a method for preparing a lithium-replenishing electrode sheet, which includes a electrode sheet substrate. The method for preparing the lithium-replenishing electrode sheet includes: using an asynchronous rolling method to use a calendering roller to calender a lithium material, with a lubricant between the lithium material and the calendering roller; laminating the calendered lithium material to the surface of the electrode sheet substrate; wherein the lubricant includes lubricating oil and inorganic particles dispersed in the lubricating oil.

[0008] In the preparation method of the lithium-supplemented electrode provided in the present application, a lithium material is placed between two calendering rollers, and a lubricant is provided between the lithium material and the calendering rollers, and then the lithium material is calendered. The inorganic particles in the lubricant can increase the friction between the lithium material and the surface of the calendering roller. With the help of asynchronous rolling, when the surface linear speeds of the two calendering rollers are different, the lithium film layer formed by the calendered lithium material can have multiple grooves and / or multiple cracks; the lubricating oil in the lubricant can facilitate the separation of the lithium film layer formed after calendering from the calendering roller, and then facilitate the coating of the lithium film layer on the surface of the active material layer of the electrode substrate to form a lithium-replenishing electrode; and because the lithium film layer obtained by calendering has multiple grooves and / or multiple cracks, when the lithium film layer is coated with the electrode substrate, there are more bonding sites (mechanical bite sites) between the lithium film layer and the electrode substrate, which can improve the bonding force between the lithium film layer and the active material layer of the electrode substrate, solving the problem that the traditional lithium film layer and the electrode substrate are difficult to coat and the bonding force between the lithium film layer and the active material layer of the electrode substrate is poor.

[0009] The lithium-replenishing pole piece prepared by the preparation method provided in the present application has a pole piece substrate and a lithium film layer located on the surface of the active material layer of the pole piece substrate, and the lithium film layer has multiple grooves and / or multiple cracks. The prepared lithium-replenishing pole piece has good wettability to the electrolyte, and the battery prepared using the lithium-replenishing pole piece has good cycle performance and good low-temperature resistance.

[0010] In some embodiments, the mass ratio of lubricating oil to inorganic particles is (30-80):(20-70). During asynchronous rolling, the mass ratio of lubricating oil to inorganic particles in the lubricant is within the above-mentioned ratio range, which not only increases the friction between the surface of the lithium material and the surface of the calendering roller, but also makes the grooves and / or cracks on the lithium film layer formed after calendering more densely distributed, so that there are more binding sites when the lithium film layer is laminated with the active material layer of the pole piece substrate, which facilitates the lamination of the lithium film layer and the pole piece substrate and is conducive to improving the bonding force between the lithium film layer and the active material layer of the pole piece substrate. At the same time, it can also facilitate the lubricant to be more evenly coated on the surface of the lithium material and / or the calendering roller, and facilitate the separation of the lithium film layer formed after calendering from the calendering roller.

[0011] In some embodiments, the inorganic particles include first particles having a volume average particle size D V 50≤1μm. The lubricant contains volume average particle size D V The first particles of 50≤1μm can make the friction between the surface of the lithium material and the surface of the calendering roller larger, so that the grooves and / or cracks on the lithium film layer formed after calendering are distributed more densely, so that there are more bonding sites when the lithium film layer and the electrode substrate are laminated, which is convenient for the lamination of the lithium film layer and the electrode substrate, and is beneficial to improving the bonding force between the lithium film layer and the active material layer of the electrode substrate.

[0012] In some embodiments, the volume average particle size D of the first particles is V 50≤500nm. The friction between the surface of the lithium material and the surface of the calendering roller can be made more appropriate, which not only makes the grooves and / or cracks on the lithium film layer formed after calendering more densely distributed, but also makes the thickness of the lithium film layer formed after calendering thinner, so that the lithium film layer formed after calendering has more binding sites when laminating with the electrode substrate, thereby making it easier for the lithium film layer formed after calendering to laminarize with the electrode substrate, which is beneficial to further improve the bonding force between the lithium film layer and the active material layer of the electrode substrate.

[0013] In some embodiments, the first particles are spherical, and the inorganic particles further include second particles, the second particles are flake-shaped, and the volume average particle size D of the second particles is V 50 is 1μm to 20μm. The lubricant contains a volume average particle size D V The second particles 50 are 1 μm to 20 μm, which can give the lubricant a certain viscosity, making it easier to form a thin and evenly covered lubricant layer on the surface of the lithium material and / or the working roller, which is beneficial to the formation of a relatively thin lithium film layer after rolling, thereby making it easier for the lithium film layer to be laminated with the electrode substrate, thereby improving the bonding force between the lithium film layer and the active material layer of the electrode substrate.

[0014] In some embodiments, the volume average particle size D of the second particles is V The volume average particle size D of the second particles is 2 μm to 7 μm. V 50 Within the above range, the viscosity of the lubricant can be made more appropriate, and the thickness of the lithium film layer formed after rolling can be made within a more appropriate range, which not only facilitates the lamination of the lithium film layer and the electrode substrate, but also fully exerts the lithium replenishing performance of the lithium film layer.

[0015] In some embodiments, the mass ratio of the second particles to the first particles is (1-10):1. When the mass ratio of the first particles to the second particles is within the above-mentioned ratio range, the viscosity of the lubricant and the friction between the lithium material and the surface of the calendering roller during calendering can be taken into account, so that the viscosity of the lubricant and the friction between the lithium material and the surface of the calendering roller during calendering are both relatively appropriate, which is not only conducive to forming a relatively thin lithium film layer after calendering, but also facilitates the formation of more binding sites when the lithium film layer formed after calendering is laminated with the electrode substrate, thereby making it easier for the lithium film layer to laminate with the electrode substrate and improving the bonding strength between the lithium film layer and the active material layer of the electrode substrate.

[0016] In some embodiments, the viscosity of the lubricant is 10,000 mPa.s to 150,000 mPa.s. A lubricant viscosity within the above range is conducive to forming a relatively thin lithium film layer after calendering; particularly when the lubricant covers the surface of the lithium material before calendering, the lubricant viscosity within the above range facilitates the formation of a thin and uniform lubricant layer on the surface of the lithium material, and is also conducive to forming a relatively thin lithium film layer after calendering, thereby facilitating the lamination of the lithium film layer with the electrode substrate and improving the bonding strength between the lithium film layer and the electrode substrate.

[0017] In some embodiments, the viscosity of the lubricant is 30,000 MPa.s to 100,000 MPa.s. The viscosity of the lubricant within the above range can ensure that the thickness of the lithium film formed after calendering is within a relatively suitable range, which not only facilitates the lamination of the lithium film layer with the electrode substrate, but also fully utilizes the lithium replenishment performance of the lithium film layer.

[0018] In some embodiments, the inorganic particles contain at least one of carbon, silicon, and sulfur.

[0019] In some embodiments, the inorganic particles are made of at least one of carbon, silicon, and sulfur. The inorganic particles selected from the aforementioned materials can increase friction between the lithium material and the surface of the calendering rollers, thereby causing the lithium film formed by the calendered lithium material to have multiple grooves and / or cracks. This facilitates lamination of the calendered lithium film with the electrode substrate and improves the bonding strength between the lithium film and the active material layer of the electrode substrate.

[0020] In some embodiments, the inorganic particles are conductive particles, which are beneficial to improving the electronic conductivity of the lithium-replenishing electrode, and further beneficial to improving the rate performance of the battery prepared using the lithium-replenishing electrode.

[0021] In some embodiments, the lubricant comprises at least one of a resin and a hydrocarbon lubricant. The lubricant is selected from the above substances to facilitate the separation of the lithium film layer formed after calendering from the calendering rollers, thereby facilitating the coating of the lithium film layer on the surface of the electrode substrate to form a lithium-replenishing electrode.

[0022] In some embodiments, the resin is selected from at least one of polyether resin and epoxy resin, so as to facilitate the separation of the lithium film layer formed after calendering from the calendering roller, and further facilitate the lithium film layer to be coated on the surface of the electrode substrate to form a lithium-replenishing electrode.

[0023] In some embodiments, the hydrocarbon lubricant is selected from at least one of polyalphaolefin lubricants, white oil, and kerosene, to facilitate the separation of the lithium film layer formed after calendering from the calendering rollers, and further facilitate the coating of the lithium film layer on the surface of the electrode substrate to form a lithium-replenishing electrode.

[0024] In some embodiments, the ratio of the surface linear speeds of the two calendering rollers is (0.03-0.1):1. This allows the grooves and / or cracks formed on the lithium film layer after calendering to be distributed more densely, so that the lithium film layer formed after calendering has more bonding sites when laminating with the electrode substrate, thereby facilitating the lamination of the lithium film layer formed after calendering with the electrode substrate and improving the bonding strength between the lithium film layer and the active material layer of the electrode substrate.

[0025] In some embodiments, the surface linear speeds of the two calendering rollers are 1 m / min to 50 m / min and 2 m / min to 100 m / min, respectively. When the surface linear speeds of the two calendering rollers are within the above ranges, not only can the grooves and / or cracks on the lithium film layer formed after calendering be more densely distributed, but the thickness of the lithium film layer formed after calendering can also be within a more appropriate range, which not only facilitates the lamination of the lithium film layer with the electrode substrate, but also fully utilizes the lithium replenishment performance of the lithium film layer.

[0026] In a second aspect, the present application provides a lithium-replenishing electrode, which includes a electrode substrate and a lithium film layer located on the surface of the active material layer of the electrode substrate; wherein the lithium film layer has multiple grooves and / or multiple cracks.

[0027] In the lithium-replenishing electrode provided in the present application, there are more binding sites (mechanical bite sites) between the lithium film layer and the active material layer of the electrode substrate, and the binding force between the lithium film layer and the active material layer of the electrode substrate is strong. Since the lithium film layer has multiple grooves and / or cracks, the prepared lithium-replenishing electrode has good wetting performance for the electrolyte, and the battery prepared using the lithium-replenishing electrode has good cycle performance and good low-temperature resistance.

[0028] In some embodiments, the surface of the lithium film layer has a striped pattern formed by grooves and / or cracks. This allows the resulting lithium-replenishing electrode to have better electrolyte wettability, and batteries fabricated using this lithium-replenishing electrode have better cycle performance and lower-temperature resistance.

[0029] In some embodiments, the lithium film layer includes a lithium material layer and a lubricant layer disposed sequentially along the direction from the electrode substrate toward the lithium film layer. The lithium material layer has a thickness of 1 μm to 15 μm. The lubricant layer includes a lubricant, which includes lubricating oil and inorganic particles dispersed within the lubricating oil. A lithium material layer thickness within this range not only facilitates lamination of the lithium film layer to the electrode substrate, but also fully utilizes the lithium replenishment properties of the lithium material layer.

[0030] In a third aspect, the present application provides a lubricant, which includes lubricating oil and inorganic particles dispersed in the lubricating oil; the mass ratio of the lubricating oil to the inorganic particles is (30-80):(20-70).

[0031] The lubricant provided by the present application is placed between the surface of the lithium material and two calendering rollers, the lithium material is calendered, and then the lithium material is coated with the active material layer of the pole piece substrate. The inorganic particles in the lubricant can increase the friction between the lithium material and the surface of the calendering roller. By means of asynchronous rolling, when the surface linear speeds of the two calendering rollers are different, the lithium film layer formed by the calendered lithium material can have multiple grooves or / and multiple cracks; the lubricating oil in the lubricant can facilitate the separation of the lithium film layer formed after calendering from the calendering roller, thereby facilitating the coating of the lithium film layer on the surface of the active material layer of the pole piece substrate to form a lithium-supplemented pole piece; and because the lithium film layer obtained by calendering has multiple grooves or / and multiple cracks, when the lithium film layer is coated with the pole piece substrate, there are more binding sites (mechanical bite sites) between the lithium film layer and the pole piece substrate, which can improve the bonding force between the lithium film layer and the active material layer of the pole piece substrate, solving the problem that the traditional lithium film layer is difficult to coat with the pole piece substrate and the bonding force between the lithium film layer and the active material layer of the pole piece substrate is poor.

[0032] In addition, the lithium-replenishing pole piece prepared using the lubricant provided above has a pole piece substrate and a lithium film layer located on the surface of the active material layer of the pole piece substrate, and the lithium film layer has multiple grooves and / or cracks. The prepared lithium-replenishing pole piece has good wettability to the electrolyte, and the battery prepared using the lithium-replenishing pole piece has good cycle performance and good low-temperature resistance.

[0033] In some embodiments, the inorganic particles include first particles having a volume average particle size D V 50≤1μm. Volume average particle size D contained in the lubricant V The first particles of 50≤1μm can make the friction between the surface of the lithium material and the surface of the calendering roller larger, so that the grooves and / or cracks on the lithium film layer formed after calendering are distributed more densely, so that there are more bonding sites when the lithium film layer and the electrode substrate are laminated, which is convenient for the lamination of the lithium film layer and the electrode substrate, and is beneficial to improving the bonding force between the lithium film layer and the active material layer of the electrode substrate.

[0034] In some embodiments, the volume average particle size D of the first particles is V 50≤500nm. The friction between the surface of the lithium material and the surface of the calendering roller can be made more appropriate, which not only makes the grooves and / or cracks on the lithium film layer formed after calendering more densely distributed, but also makes the thickness of the lithium film layer formed after calendering thinner, so that the lithium film layer formed after calendering has more binding sites when laminating with the electrode substrate, thereby making it easier for the lithium film layer formed after calendering to laminarize with the electrode substrate, which is beneficial to further improve the bonding force between the lithium film layer and the active material layer of the electrode substrate.

[0035] In some embodiments, the first particles are spherical, and the inorganic particles further include second particles, the second particles are flake-shaped, and the volume average particle size D of the second particles is V 50 is 1μm to 20μm. The lubricant contains a volume average particle size D V The second particles 50 are 1 μm to 20 μm, which can give the lubricant a certain viscosity, making it easier to form a thin and evenly covered lubricant layer on the surface of the lithium material, which is beneficial to the formation of a relatively thin lithium film layer after calendering, and further facilitates the lamination of the lithium film layer with the electrode substrate, thereby improving the bonding force between the lithium film layer and the active material layer of the electrode substrate.

[0036] In some embodiments, the mass ratio of the second particles to the first particles is (1-10):1. When the mass ratio of the first particles to the second particles is within the above-mentioned ratio range, the viscosity of the lubricant and the friction between the lithium material and the surface of the calendering roller during calendering can be taken into account, so that the viscosity of the lubricant and the friction between the lithium material and the surface of the calendering roller during calendering are both relatively appropriate, which is not only conducive to forming a relatively thin lithium film layer after calendering, but also facilitates the formation of more binding sites when the lithium film layer formed after calendering is laminated with the electrode substrate, thereby making it easier for the lithium film layer to laminate with the electrode substrate and improving the bonding strength between the lithium film layer and the active material layer of the electrode substrate.

[0037] In some embodiments, the viscosity of the lubricant is 10000 mPa.s to 150000 mPa.s; the viscosity of the lubricant is within the above range, which is conducive to the formation of a relatively thin lithium film layer after calendering; especially for the case where the lubricant covers the surface of the lithium material before calendering, the viscosity of the lubricant is within the above range, which is convenient for forming a thin and uniformly covered lubricant layer on the surface of the lithium material, and is also conducive to the formation of a relatively thin lithium film layer after calendering, thereby making it easier for the lithium film layer to be laminated with the electrode substrate, thereby improving the bonding strength between the lithium film layer and the electrode substrate.

[0038] In a fourth aspect, the present application provides a battery comprising the lithium supplement electrode provided by any one of the second aspects above. The battery provided by the present application has high cycle performance and low low-temperature resistance.

[0039] In a fifth aspect, the present application provides an electrical device, which includes the battery provided in the fourth aspect.

[0040] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0042] FIG1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0043] FIG2 is a schematic diagram of the exploded structure of a battery provided in some embodiments of the present application;

[0044] FIG3 is a schematic structural diagram of a battery cell provided in some embodiments of the present application;

[0045] FIG4 is an exploded view of a battery cell provided in some embodiments of the present application;

[0046] FIG5 is a cross-sectional view of a lithium-supplemented electrode with a continuous lithium film layer laminated to an electrode substrate;

[0047] FIG6 is a cross-sectional view of a lithium-replenishing electrode provided in some embodiments of the present application;

[0048] FIG7 is a photograph of the lithium film layer obtained in Example 1;

[0049] FIG8 is a photograph of the lithium film layer prepared in Comparative Example 1.

[0050] Icon: 1000-vehicle; 100-battery; 10-housing; 11-accommodation space; 12-first part; 13-second part; 20-battery cell; 21-housing; 211-opening; 22-end cover assembly; 221-end cover; 222-electrode terminal; 23-electrode assembly; 24-current collecting member; 25-insulating protection member; 200-controller; 300-motor.

[0051] 1-lithium replenishing electrode; 2-electrode substrate; 3-lithium membrane layer; 4-lithium material layer; 5-lubricating oil layer.

[0052] 400 - lithium replenishing electrode; 410 - electrode substrate; 420 - lithium film layer; 421 - lithium material layer; 422 - lubricant layer. DETAILED DESCRIPTION

[0053] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0054] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0055] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0056] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0057] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0058] In the description of the embodiments of the present application, the orientation or positional relationship indicated by technical terms such as "length", "width", "thickness", "bottom", "inside" and "outside" is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the embodiments of the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be understood as a limitation on the embodiments of the present application.

[0059] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installation," "connection," and "fixation" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; internal connections between two components or interactions between two components. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0060] Currently, market developments indicate that power batteries are becoming increasingly widely used. They are not only used in energy storage systems such as hydropower, thermal, wind, and solar power plants, but are also widely used in electric vehicles like electric bicycles, electric motorcycles, and electric vehicles, as well as in military equipment and aerospace. As power battery applications continue to expand, market demand is also growing.

[0061] Power batteries can be lithium-ion batteries. During the charging process, lithium ions are released from the positive electrode active material, transported through the electrolyte, passed through the separator, and embedded in the negative electrode active material. To improve the battery's initial efficiency and cycle performance, lithium-ion batteries often use lithium-supplemented electrodes.

[0062] The preparation method for lithium-replenishing pole pieces is as follows: lubricating oil is applied to the surface of the lithium material, and then the lithium material is placed between two working rollers to roll the lithium material to form a continuous lithium film layer; the rolled continuous lithium film layer is laminated with the active material layer of the pole piece substrate, so that the continuous lithium film layer covers and bonds to the active material layer of the pole piece substrate, forming a lithium-replenishing pole piece. However, when the continuous lithium film layer is laminated with the pole piece substrate, the bonding strength between the active material layer of the pole piece substrate and the continuous lithium film layer is poor, and lamination of the continuous lithium film layer and the pole piece substrate is often difficult, or even impossible.

[0063] Based on the above considerations, in order to solve the problem of difficult lamination of the lithium film layer and the electrode substrate and poor bonding between the lithium film layer and the active material layer of the electrode substrate, the present application designs a method for preparing a lithium-supplemented electrode, including: adopting an asynchronous rolling method, using a calendering roller to calender the lithium material, with a lubricant between the lithium material and the calendering roller; laminating the calendered lithium material to the surface of the electrode substrate; wherein the lubricant includes lubricating oil and inorganic particles dispersed in the lubricating oil.

[0064] In the preparation method of the lithium-supplemented electrode provided in the present application, a lithium material is placed between two calendering rollers, and a lubricant is provided between the lithium material and the calendering rollers, and then the lithium material is calendered. The inorganic particles in the lubricant can increase the friction between the lithium material and the surface of the calendering roller. With the help of asynchronous rolling, when the surface linear speeds of the two calendering rollers are different, the lithium film layer formed by the calendered lithium material can have multiple grooves and / or multiple cracks; the lubricating oil in the lubricant can facilitate the separation of the lithium film layer formed after calendering from the calendering roller, and then facilitate the coating of the lithium film layer on the surface of the active material layer of the electrode substrate to form a lithium-replenishing electrode; and because the lithium film layer obtained by calendering has multiple grooves and / or multiple cracks, when the lithium film layer is coated with the electrode substrate, there are more bonding sites (mechanical bite sites) between the lithium film layer and the electrode substrate, which can improve the bonding force between the lithium film layer and the active material layer of the electrode substrate, solving the problem that the traditional lithium film layer and the electrode substrate are difficult to coat and the bonding force between the lithium film layer and the active material layer of the electrode substrate is poor.

[0065] The lithium-replenishing pole piece prepared by the preparation method provided in the present application has a pole piece substrate and a lithium film layer located on the surface of the active material layer of the pole piece substrate, and the lithium film layer has multiple grooves and / or multiple cracks. The prepared lithium-replenishing pole piece has good wettability to the electrolyte, and the battery prepared using the lithium-replenishing pole piece has good cycle performance and good low-temperature resistance.

[0066] The lithium-supplemented electrode sheet prepared in this manner can be used as a negative electrode sheet. This negative electrode sheet can be assembled with a positive electrode sheet, an electrolyte, and a separator to form a battery. This battery can be a single cell, a module, a battery pack, etc., and can be used, but not limited to, in electrical equipment such as vehicles, ships, and aircraft. The battery disclosed in this application can be used to form a power supply system for such an electrical equipment, thereby improving the battery's cycle performance and service life at higher temperatures.

[0067] The embodiments of the present application provide an electrical device that uses a battery as a power source. The electrical device may be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, and the like. The vehicle may be a fuel vehicle, a gas vehicle, or a new energy vehicle. The new energy vehicle may be a pure electric vehicle, a hybrid vehicle, or an extended-range vehicle. The spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft. The electric toys may include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys. The electric tools may include metal cutting electric tools, grinding electric tools, assembly electric tools, and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers. The embodiments of the present application do not impose any special restrictions on the above-mentioned electrical devices.

[0068] For the convenience of description, the following embodiments are described by taking the electric device as a vehicle as an example.

[0069] Please refer to Figure 1, which is a schematic diagram of the structure of a vehicle 1000 provided in some embodiments of the present application. A battery 100 is disposed within vehicle 1000. Battery 100 can be located at the bottom, front, or rear of vehicle 1000. Battery 100 can be used to power vehicle 1000, for example, as an operating power source for vehicle 1000.

[0070] The vehicle 1000 may further include a controller 200 and a motor 300 . The controller 200 is used to control the battery 100 to supply power to the motor 300 , for example, to meet the power requirements of the vehicle 1000 during startup, navigation, and driving.

[0071] In some embodiments of the present application, the battery 100 can not only serve as the operating power source of the vehicle 1000, but also serve as the driving power source of the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0072] FIG2 is a schematic diagram of the exploded structure of a battery 100 provided in some embodiments of the present application. Referring to FIG2 , the battery 100 includes a housing 10 and a battery cell 20 , wherein the battery cell 20 is housed in the housing 10 .

[0073] The housing 10 is used to provide a storage space 11 for the battery cells 20. In some embodiments, the housing 10 may include a first portion 12 and a second portion 13, which overlap to define the storage space 11 for accommodating the battery cells 20. Of course, the connection between the first portion 12 and the second portion 13 can be sealed by a seal (not shown), such as a sealing ring, sealant, or the like.

[0074] The first portion 12 and the second portion 13 can have various shapes, such as a rectangular parallelepiped, a cylinder, etc. The first portion 12 can be a hollow structure with an opening on one side to form a receiving cavity for accommodating the battery cell 20. The second portion 13 can also be a hollow structure with an opening on one side to form a receiving cavity for accommodating the battery cell 20. The open side of the second portion 13 covers the open side of the first portion 12, thereby forming the box 10 with the receiving space 11. Of course, as shown in Figure 2, the first portion 12 can also be a hollow structure with an opening on one side, and the second portion 13 can be a plate-like structure. The second portion 13 covers the open side of the first portion 12, thereby forming the box 10 with the receiving space 11.

[0075] In the battery 100, there can be one or more battery cells 20. If there are multiple battery cells 20, the multiple battery cells 20 can be connected in series, in parallel, or in a mixed connection. Mixed connection means that the multiple battery cells 20 are connected in series and in parallel. The multiple battery cells 20 can be directly connected in series, in parallel, or in a mixed connection, and then the whole formed by the multiple battery cells 20 is accommodated in the box 10; of course, it is also possible that the multiple battery cells 20 are first connected in series, in parallel, or in a mixed connection to form a battery module, and the multiple battery modules are then connected in series, in parallel, or in a mixed connection to form a whole, and accommodated in the box 10. The battery cell 20 can be cylindrical, flat, rectangular, or in other shapes. Figure 2 exemplifies the case where the battery cell 20 is square.

[0076] In some embodiments, the battery 100 may further include a busbar component (not shown), and the multiple battery cells 20 may be electrically connected via the busbar component to achieve series connection, parallel connection, or mixed connection of the multiple battery cells 20 .

[0077] Figure 3 is a schematic diagram of the structure of a battery cell 20 provided in some embodiments of the present application, and Figure 4 is an exploded view of a battery cell 20 provided in some embodiments of the present application. Referring to Figures 3 and 4, the battery cell 20 may include a housing 21, an end cap assembly 22, and an electrode assembly 23. The housing 21 has an opening 211, and the electrode assembly 23 is accommodated within the housing 21. The end cap assembly 22 is used to seal the opening 211.

[0078] The shape of the housing 21 can be determined according to the specific shape of the electrode assembly 23. For example, if the electrode assembly 23 is a rectangular parallelepiped structure, the housing 21 can be a rectangular parallelepiped structure. Figures 3 and 4 exemplarily show the case where the housing 21 and the electrode assembly 23 are square.

[0079] The shell 21 may be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc., and the embodiment of the present application does not impose any special restrictions on this.

[0080] The end cap assembly 22 includes an end cap 221 and an electrode terminal 222. The end cap assembly 22 is used to seal the opening 211 of the outer shell 21 to form a sealed installation space (not shown), which is used to accommodate the electrode assembly 23. The installation space is also used to accommodate an electrolyte, such as an electrolyte. The end cap assembly 22 serves as a component for outputting the electrical energy of the electrode assembly 23. The electrode terminal 222 in the end cap assembly 22 is used to electrically connect to the electrode assembly 23, that is, the electrode terminal 222 is electrically connected to the tab of the electrode assembly 23. For example, the electrode terminal 222 is connected to the tab through the current collecting member 24 to achieve electrical connection between the electrode terminal 222 and the tab.

[0081] It should be noted that the number of openings 211 of the outer shell 21 can be one or two. If the number of openings 211 of the outer shell 21 is one, the number of end cap assembly 22 can also be one, and two electrode terminals 222 can be provided in the end cap assembly 22. The two electrode terminals 222 are respectively used to electrically connect to the positive electrode tab and the negative electrode tab of the electrode assembly 23. If the number of openings 211 of the outer shell 21 is two, for example, the two openings 211 are provided on opposite sides of the outer shell 21, the number of end cap assemblies 22 can also be two, and the two end cap assemblies 22 are respectively covered on the two openings 211 of the outer shell 21. In this case, the electrode terminal 222 in one end cap assembly 22 can be a positive electrode terminal, which is used to electrically connect to the positive electrode tab of the electrode assembly 23; and the electrode terminal 222 in the other end cap assembly 22 can be a negative electrode terminal, which is used to electrically connect to the negative electrode sheet of the electrode assembly 23.

[0082] In some embodiments, as shown in FIG4 , the battery cell 20 may further include an insulating protective member 25 fixed to the periphery of the electrode assembly 23, and the insulating protective member 25 is used to insulate and isolate the electrode assembly 23 from the housing 21. Exemplarily, the insulating protective member 25 is a tape bonded to the periphery of the electrode assembly 23. In some embodiments, there are multiple electrode assemblies 23, and the insulating protective member 25 is arranged around the periphery of the multiple electrode assemblies 23, and the multiple electrode assemblies 23 are formed into an integral structure to maintain the structural stability of the electrode assembly 23. Among them, the electrode assembly 23 can be a wound electrode assembly or a laminated electrode assembly, and the embodiments of the present application are not limited thereto.

[0083] The electrode assembly 23 includes a positive electrode sheet, a negative electrode sheet, and a separator, and the separator is arranged between the positive electrode sheet and the negative electrode sheet.

[0084] This application has no special restrictions on the positive electrode sheet and the separator.

[0085] The isolation membrane may be a PP (polypropylene) porous membrane, a PE (polyethylene) porous membrane, a polyimide porous membrane, or a porous membrane formed by a composite of multiple polymers.

[0086] The positive electrode sheet includes a positive electrode current collector and a positive electrode active layer covering at least one surface of the positive electrode current collector in the thickness direction; the material of the positive electrode current collector may include aluminum foil, foamed aluminum, aluminum composite current collector (a current collector with a polymer support layer in the middle and aluminum metal layers on both surfaces of the support layer), nickel foil, foamed nickel, etc.; the positive electrode active material in the positive electrode active layer includes one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide and olivine structure lithium-containing phosphate, for example, nickel cobalt manganese oxide Lithium, lithium nickel cobalt aluminum oxide, lithium cobalt oxide, lithium iron phosphate, lithium manganate, etc.; the binder in the positive electrode active layer is selected from at least one of vinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyacrylate, carboxymethyl cellulose sodium salt, styrene-butadiene rubber, polyurethane, ethylene-vinyl acetate copolymer and ethylene-acrylic acid copolymer; the dispersant in the positive electrode active layer is selected from polyvinyl pyrrolidone, etc.; the conductive particles in the positive electrode active layer are selected from at least one of conductive carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanotubes, graphene, activated carbon, graphite flakes, graphite particles and mesophase carbon microbeads.

[0087] The negative electrode sheet uses a lithium-supplemented electrode sheet. In this application, the preparation method of the lithium-supplemented electrode sheet includes: rolling a lithium material using asynchronous rolling; then coating the rolled lithium material on the surface of the active material layer of the electrode substrate; wherein, during rolling, a lubricant is provided between the lithium material and the rolling rollers; the lubricant includes lubricating oil and inorganic particles dispersed in the lubricating oil.

[0088] Among them, "rolling the lithium material by asynchronous rolling" means: placing the lithium material between two working rolls, and when rolling the lithium material, the surface linear speeds of the two working rolls are different.

[0089] "There is a lubricant between the lithium material and the calendering roller" can be achieved in the following three ways: Method 1: Covering the lubricant on the surface of the lithium material (for example, by coating); Method 2: Covering the lubricant on the surface of the calendering roller (for example, by coating); Method 3: Covering the lubricant on both the surface of the calendering roller and the surface of the lithium material.

[0090] The electrode substrate includes a negative electrode current collector and a negative electrode active layer covering at least one surface of the negative electrode current collector in the thickness direction. The negative electrode current collector can be made of aluminum foil, copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, or a polymer substrate coated with a conductive metal. The conductive metal includes, but is not limited to, copper, nickel, or titanium. The polymer substrate can be made of, but is not limited to, at least one of polyethylene, polypropylene, ethylene-propylene copolymer, polyethylene terephthalate, polyethylene naphthalate, and poly(p-phenylene terephthalamide). The negative electrode active layer includes graphite, coke, and the like. The conductive agent in the negative electrode active layer may include, but is not limited to, a carbon material, a metal, or a conductive polymer. The carbon material may include at least one of conductive carbon black (Super P), carbon nanotubes (CNTs), carbon nanofibers, natural graphite, artificial graphite, flake graphite, carbon dots, or graphene. The metal may include metal powder or metal fiber of copper, iron, aluminum, etc. The conductive polymer may include at least one of polythiophene, polypyrrole, polyaniline, polyphenylene, and polyphenylene vinylene. The binder in the negative electrode active layer may include, but is not limited to, at least one of polypropylene alcohol, sodium polyacrylate, potassium polyacrylate, lithium polyacrylate, polyimide, polyamide-imide, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl pyrrolidone, polyethylene, polypropylene, epoxy resin, nylon, styrene-butadiene rubber (SBR), polyvinyl alcohol (PVA), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl butyral, water-based acrylic resin, carboxymethyl cellulose (CMC), or sodium carboxymethyl cellulose (CMC-Na).

[0091] FIG5 is a cross-sectional view of a lithium-replenishing electrode 1 in which a continuous lithium film layer 3 and an electrode substrate 2 are laminated. FIG6 is a cross-sectional view of a lithium-replenishing electrode 400 provided in some embodiments of the present application.

[0092] In the preparation method of the lithium-supplemented electrode provided in the present application, an asynchronous rolling method is adopted, and a lithium material is rolled using a rolling roller, with a lubricant between the lithium material and the rolling roller; the rolled lithium material is coated on the surface of the electrode substrate 410; wherein the lubricant includes lubricating oil and inorganic particles dispersed in the lubricating oil.

[0093] The lithium material is placed between two calendering rollers, and a lubricant is provided between the lithium material and the calendering rollers, and then the lithium material is calendered. The inorganic particles in the lubricant can increase the friction between the lithium material and the surface of the calendering roller. By means of asynchronous rolling, when the surface linear speeds of the two calendering rollers are different, the lithium film layer 420 formed by the calendered lithium material can have multiple grooves or / and multiple cracks (for example, the striped lithium film layer 420 structure as shown in FIG6 , the lithium film layer 420 includes a lithium material layer 421 and a lubricant layer 422 covering the surface of the lithium material layer 421). The lubricating oil in the lubricant can facilitate the separation of the lithium film layer 420 formed after calendering from the calendering roller, thereby facilitating the adhesion of the lithium film layer 420 to the surface of the active material layer of the electrode substrate 410 to form a lithium-supplementing electrode 400.

[0094] Comparing Figures 5 and 6, in Figure 5, the lithium film layer 3 is a continuous lithium film layer (including a lithium material layer 4 and a lubricating oil layer 5 covering the surface of the lithium material layer 4), and the entire continuous lithium film layer 3 is laminated with the active material layer of the electrode substrate 2 to form a lithium-supplemented electrode 1. In the present application, referring to Figure 6, since the lithium film layer 420 obtained by calendering is discontinuous, when the lithium film layer 420 is laminated with the electrode substrate 410, there are more binding sites (mechanical bite sites) between the lithium film layer 420 and the active material layer of the electrode substrate 410, which can improve the bonding strength between the lithium film layer 420 and the active material layer of the electrode substrate 410, solving the problem that the traditional continuous lithium film layer 420 is difficult to laminate with the electrode substrate 410 and the bonding strength between the lithium film layer 420 and the active material layer of the electrode substrate 410 is poor.

[0095] The lithium-replenishing pole piece 400 is prepared using the preparation method provided in the present application. The lithium-replenishing pole piece 400 has a pole piece substrate 410 and a lithium film layer 420 located on the surface of the active material layer of the pole piece substrate 410, and the lithium film layer 420 has multiple grooves and / or multiple cracks. The prepared lithium-replenishing pole piece 400 has good wettability to the electrolyte, and the battery prepared using the lithium-replenishing pole piece 400 has good cycle performance and good low-temperature resistance.

[0096] In some embodiments, the mass ratio of lubricating oil to inorganic particles in the lubricant is (30-80):(20-70). During asynchronous rolling, the mass ratio of lubricating oil to inorganic particles in the lubricant is within the above-mentioned ratio range, which not only increases the friction between the surface of the lithium material and the surface of the calendering roller, but also makes the grooves and / or cracks on the lithium film layer formed after calendering more densely distributed, so that there are more binding sites when the lithium film layer is laminated with the active material layer of the pole piece substrate, which facilitates the lamination of the lithium film layer and the pole piece substrate and is conducive to improving the bonding force between the lithium film layer and the active material layer of the pole piece substrate. At the same time, it can also facilitate the lubricant to be more evenly coated on the surface of the lithium material and / or the calendering roller, and facilitate the separation of the lithium film layer formed after calendering from the calendering roller.

[0097] As an example, in the lubricant, the mass ratio of lubricating oil to inorganic particles can be any value among 30:70, 40:60, 50:50, 55:45, 60:40, 65:35, 70:30, 75:25 and 80:20, or a range value between any two of them.

[0098] In some embodiments, the inorganic particles include first particles having a volume average particle size D V 50≤1μm.

[0099] The lubricant contains a volume average particle size D V The first particles of 50≤1μm can make the friction between the surface of the lithium material and the surface of the calendering roller larger, so that the grooves and / or cracks on the lithium film layer formed after calendering are distributed more densely, so that there are more bonding sites when the lithium film layer and the electrode substrate are laminated, which is convenient for the lamination of the lithium film layer and the electrode substrate, and is beneficial to improving the bonding force between the lithium film layer and the active material layer of the electrode substrate.

[0100] As an example, the volume average particle size D of the first particles is V 50 can be any value among 1 μm, 800 nm, 600 nm, 500 nm, 450 nm, 300 nm, 150 nm, 100 nm and 50 nm, or a range between any two of them.

[0101] In some embodiments, the volume average particle size D of the first particles is V 50≤500nm. The friction between the surface of the lithium material and the surface of the calendering roller can be made more appropriate, which not only makes the grooves and / or cracks on the lithium film layer formed after calendering more densely distributed, but also makes the thickness of the lithium film layer formed after calendering thinner, so that the lithium film layer formed after calendering has more binding sites when laminating with the electrode substrate, thereby making it easier for the lithium film layer formed after calendering to laminarize with the electrode substrate, which is beneficial to further improve the bonding force between the lithium film layer and the active material layer of the electrode substrate.

[0102] In some embodiments, the first particles are spherical, and the inorganic particles further include second particles, the second particles are flake-shaped, and the volume average particle size D of the second particles is V 50 is 1μm~20μm.

[0103] The first particles being spherical means that the first particles can be spherical or quasi-spherical particles.

[0104] The lubricant contains a volume average particle size D V50 is a second particle of 1μm to 20μm, which can give the lubricant a certain viscosity, making it easier to form a thin and evenly covered lubricant layer on the surface of the lithium material and / or the working roller, which is beneficial to the formation of a relatively thin lithium film layer after rolling, and further facilitates the lamination of the lithium film layer and the electrode substrate, thereby improving the bonding strength between the lithium film layer and the electrode substrate.

[0105] As an example, the volume average particle size D of the second particles is V 50 can be any value among 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm and 20μm, or a range between any two of them.

[0106] In some embodiments, the volume average particle size D of the second particles is V 50 is 2μm to 7μm. The volume average particle size D of the flaky particles V 50 Within the above range, the viscosity of the lubricant can be made more appropriate, and the thickness of the lithium film layer formed after rolling can be made within a more appropriate range, which not only facilitates the lamination of the lithium film layer and the electrode substrate, but also fully exerts the lithium replenishing performance of the lithium film layer.

[0107] As an example, the volume average particle size D of the second particles is V 50 can be any value among 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 4.5μm, 5μm, 5.5μm, 6μm, 6.5μm and 7μm, or a range between any two of them.

[0108] In some embodiments, the mass ratio of the second particles to the first particles is (1-10):1. When the mass ratio of the first particles to the second particles is within the above-mentioned ratio range, the viscosity of the lubricant and the friction between the lithium material and the surface of the calendering roller during calendering can be taken into account, so that the viscosity of the lubricant and the friction between the lithium material and the surface of the calendering roller during calendering are both relatively appropriate, which is not only conducive to forming a relatively thin lithium film layer after calendering, but also facilitates the formation of more binding sites when the lithium film layer formed after calendering is laminated with the electrode substrate, thereby making it easier for the lithium film layer to laminate with the electrode substrate and improving the bonding strength between the lithium film layer and the active material layer of the electrode substrate.

[0109] As an example, the mass ratio of the second particles to the first particles can be any value among 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1 and 10:1, or a range between any two values.

[0110] In some embodiments, the viscosity of the lubricant is 10,000 mPa.s to 150,000 mPa.s. A lubricant viscosity within the above range is conducive to forming a relatively thin lithium film layer after calendering; particularly when the lubricant covers the surface of the lithium material before calendering, the lubricant viscosity within the above range facilitates the formation of a thin and uniform lubricant layer on the surface of the lithium material, and is also conducive to forming a relatively thin lithium film layer after calendering, thereby facilitating the lamination of the lithium film layer with the electrode substrate and improving the bonding strength between the lithium film layer and the electrode substrate.

[0111] As an example, the viscosity of the lubricant can be 10000 mPa.s, 15000 mPa.s, 20000 mPa.s, 25000 mPa.s, 30000 mPa.s, 35000 mPa.s, 40000 mPa.s, 45000 mPa.s, 50000 mPa.s, 55000 mPa.s, 60000 mPa.s, 65000 mPa. Any value among 10000mpa.s, 70000mpa.s, 75000mpa.s, 80000mpa.s, 85000mpa.s, 90000mpa.s, 100000mpa.s, 110000mpa.s, 120000mpa.s, 130000mpa.s, 140000mpa.s and 150000mpa.s or any range between any two of them.

[0112] In some embodiments, the viscosity of the lubricant is 30,000 MPa.s to 100,000 MPa.s. The viscosity of the lubricant within the above range can ensure that the thickness of the lithium film formed after calendering is within a relatively suitable range, which not only facilitates the lamination of the lithium film layer with the electrode substrate, but also fully utilizes the lithium replenishment performance of the lithium film layer.

[0113] In some embodiments, the inorganic particles contain at least one of carbon, silicon, and sulfur.

[0114] In some embodiments, the inorganic particles are made of at least one of carbon, silicon, and sulfur. The inorganic particles selected from the aforementioned materials can increase friction between the lithium material and the surface of the calendering rollers, thereby causing the lithium film formed by the calendered lithium material to have multiple grooves and / or cracks. This facilitates lamination of the calendered lithium film with the electrode substrate and improves the bonding strength between the lithium film and the active material layer of the electrode substrate.

[0115] As an example, the carbon element may include at least one of carbon black (Super P), carbon nanotubes (CNTs), carbon nanofibers, natural graphite, artificial graphite, flake graphite, carbon dots, and graphene.

[0116] In some embodiments, the inorganic particles are conductive particles, which are beneficial to improving the electronic conductivity of the lithium-replenishing electrode, and further beneficial to improving the rate performance of the battery prepared using the lithium-replenishing electrode.

[0117] In some embodiments, the lubricant comprises at least one of a resin and a hydrocarbon lubricant. The lubricant is selected from the above substances to facilitate the separation of the lithium film layer formed after calendering from the calendering rollers, thereby facilitating the coating of the lithium film layer on the surface of the electrode substrate to form a lithium-replenishing electrode.

[0118] In some embodiments, the resin is selected from at least one of polyether resin and epoxy resin, so as to facilitate the separation of the lithium film layer formed after calendering from the calendering roller, and further facilitate the lithium film layer to be coated on the surface of the electrode substrate to form a lithium-replenishing electrode.

[0119] As an example, the polyether resin can be selected from polyoxymethylene or polychlorohydrin ether, etc.; the epoxy resin can be selected from bisphenol A epoxy resin, polyphenol glycidyl ether epoxy resin, aliphatic glycidyl ether epoxy resin or glycidyl ether epoxy resin.

[0120] In some embodiments, the hydrocarbon lubricant is selected from at least one of polyalphaolefin lubricants, white oil, and kerosene, to facilitate the separation of the lithium film layer formed after calendering from the calendering rollers, and further facilitate the coating of the lithium film layer on the surface of the electrode substrate to form a lithium-replenishing electrode.

[0121] As an example, the poly-alpha-olefin lubricating oil may be poly-alpha-olefin (PAO).

[0122] In some embodiments, the calendering step includes: the ratio of the surface linear speeds of the two calendering rollers is (0.03-0.1):1. This can result in a denser distribution of the grooves and / or cracks on the lithium film layer formed after calendering, so that the lithium film layer formed after calendering has more bonding sites when laminating with the electrode substrate, thereby facilitating the lamination of the lithium film layer formed after calendering with the electrode substrate and improving the bonding strength of the active material layer between the lithium film layer and the electrode substrate.

[0123] Here, the surface linear velocity of the calendering roll refers to the linear velocity of a mass point on the roll surface of the calendering roll.

[0124] As an example, the ratio of the surface linear speeds of the two calendering rollers can be any value among 0.03:1, 0.035:1, 0.04:1, 0.045:1, 0.05:1, 0.055:1, 0.06:1, 0.065:1, 0.07:1, 0.075:1, 0.08:1, 0.085:1, 0.09:1, 0.095:1 and 0.1:1, or a range between any two of them.

[0125] In some embodiments, the surface linear speeds of the two calendering rollers are 1 m / min to 50 m / min and 2 m / min to 100 m / min, respectively. When the surface linear speeds of the two calendering rollers are within the above ranges, not only can the grooves and / or cracks on the lithium film layer formed after calendering be more densely distributed, but the thickness of the lithium film layer formed after calendering can also be within a more appropriate range, which not only facilitates the lamination of the lithium film layer with the electrode substrate, but also fully utilizes the lithium replenishment performance of the lithium film layer.

[0126] The two calendering rollers are defined as a first calendering roller and a second calendering roller. As an example, the surface linear velocity of the first calendering roller can be any value among 1 m / min, 5 m / min, 10 m / min, 15 m / min, 20 m / min, 25 m / min, 30 m / min, 35 m / min, 40 m / min, 45 m / min and 50 m / min, or a range between any two values; the surface linear velocity of the second calendering roller can be any value among 2 m / min, 5 m / min, 10 m / min, 20 m / min, 30 m / min, 40 m / min, 50 m / min, 60 m / min, 70 m / min, 80 m / min, 90 m / min, 95 m / min and 100 m / min, or a range between any two values.

[0127] The present application also provides a lithium-replenishing electrode, as shown in FIG6 , the lithium-replenishing electrode 400 includes an electrode substrate 410 and a lithium film layer 420 located on at least one surface in the thickness direction of the electrode substrate 410 ; wherein the lithium film layer 420 has multiple grooves and / or multiple cracks.

[0128] In the lithium-replenishing pole piece 400 provided in the present application, there are more bonding sites (mechanical bite sites) between the lithium film layer 420 and the pole piece substrate 410, and the bonding force between the lithium film layer 420 and the pole piece substrate 410 is relatively strong. Since the lithium film layer 420 has multiple grooves and / or multiple cracks, the prepared lithium-replenishing pole piece 400 has better wettability to the electrolyte, and the battery prepared using the lithium-replenishing pole piece 400 has better cycle performance and better low-temperature resistance.

[0129] In some embodiments, the surface of the lithium film layer 420 has a striped pattern formed by grooves and / or cracks. This allows the lithium-replenishing electrode 400 to have better electrolyte wettability, and a battery manufactured using the lithium-replenishing electrode 400 has better cycle performance and low-temperature resistance.

[0130] In some embodiments, along the direction from the electrode substrate 410 to the lithium film layer 420, the lithium film layer 420 includes a lithium material layer 421 and a lubricant layer 422 disposed sequentially. The thickness of the lithium material layer 421 is 1 μm to 15 μm. The lubricant layer 422 includes a lubricant, which includes lubricating oil and inorganic particles dispersed within the lubricating oil. A thickness of the lithium material layer 421 within this range not only facilitates lamination of the lithium film layer 420 with the electrode substrate 410, but also fully utilizes the lithium replenishment properties of the lithium material layer.

[0131] As an example, the thickness of the lithium material layer 421 can be any value among 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm and 15μm, or a range between any two values.

[0132] The present application also provides a lubricant, which includes lubricating oil and inorganic particles dispersed in the lubricating oil; the mass ratio of the lubricating oil to the inorganic particles is (30-80):(20-70).

[0133] The lubricant provided by the present application is placed between the surface of the lithium material and two calendering rollers, the lithium material is calendered, and then the lithium material is coated with the active material layer of the pole piece substrate. The inorganic particles in the lubricant can increase the friction between the lithium material and the surface of the calendering roller. By means of asynchronous rolling, when the surface linear speeds of the two calendering rollers are different, the lithium film layer formed by the calendered lithium material can have multiple grooves or / and multiple cracks; the lubricating oil in the lubricant can facilitate the separation of the lithium film layer formed after calendering from the calendering roller, thereby facilitating the coating of the lithium film layer on the surface of the active material layer of the pole piece substrate to form a lithium-supplemented pole piece; and because the lithium film layer obtained by calendering has multiple grooves or / and multiple cracks, when the lithium film layer is coated with the pole piece substrate, there are more binding sites (mechanical bite sites) between the lithium film layer and the pole piece substrate, which can improve the bonding force between the lithium film layer and the active material layer of the pole piece substrate, solving the problem that the traditional lithium film layer is difficult to coat with the pole piece substrate and the bonding force between the lithium film layer and the active material layer of the pole piece substrate is poor.

[0134] In addition, the lithium-replenishing pole piece prepared using the lubricant provided above has a pole piece substrate and a lithium film layer located on the surface of the active material layer of the pole piece substrate, and the lithium film layer has multiple grooves and / or cracks. The prepared lithium-replenishing pole piece has good wettability to the electrolyte, and the battery prepared using the lithium-replenishing pole piece has good cycle performance and good low-temperature resistance.

[0135] In some embodiments, the inorganic particles include first particles having a volume average particle size D V 50≤1μm. The lubricant contains volume average particle size D VThe first particles of 50≤1μm can make the friction between the surface of the lithium material and the surface of the calendering roller larger, so that the grooves and / or cracks on the lithium film layer formed after calendering are distributed more densely, so that there are more bonding sites when the lithium film layer and the electrode substrate are laminated, which is convenient for the lamination of the lithium film layer and the electrode substrate, and is beneficial to improving the bonding force between the lithium film layer and the active material layer of the electrode substrate.

[0136] In some embodiments, the volume average particle size D of the first particles is V 50≤500nm. The friction between the surface of the lithium material and the surface of the calendering roller can be made more appropriate, which not only makes the grooves and / or cracks on the lithium film layer formed after calendering more densely distributed, but also makes the thickness of the lithium film layer formed after calendering thinner, so that the lithium film layer formed after calendering has more binding sites when laminating with the electrode substrate, thereby making it easier for the lithium film layer formed after calendering to laminarize with the electrode substrate, which is beneficial to further improve the bonding force between the lithium film layer and the active material layer of the electrode substrate.

[0137] In some embodiments, the first particles are spherical, and the inorganic particles further include second particles, the second particles are flake-shaped, and the volume average particle size D of the second particles is V 50 is 1μm to 20μm. The lubricant contains a volume average particle size D V The second particles 50 are 1 μm to 20 μm, which can give the lubricant a certain viscosity, making it easier to form a thin and evenly covered lubricant layer on the surface of the lithium material and / or the working roller, which is beneficial to the formation of a relatively thin lithium film layer after rolling, thereby making it easier for the lithium film layer to be laminated with the electrode substrate, thereby improving the bonding force between the lithium film layer and the active material layer of the electrode substrate.

[0138] In some embodiments, the mass ratio of the second particles to the first particles is (1-10):1. When the mass ratio of the first particles to the second particles is within the above-mentioned ratio range, the viscosity of the lubricant and the friction between the lithium material and the surface of the calendering roller during calendering can be taken into account, so that the viscosity of the lubricant and the friction between the lithium material and the surface of the calendering roller during calendering are both relatively appropriate, which is not only conducive to forming a relatively thin lithium film layer after calendering, but also facilitates the formation of more binding sites when the lithium film layer formed after calendering is laminated with the electrode substrate, thereby making it easier for the lithium film layer to laminate with the electrode substrate and improving the bonding strength between the lithium film layer and the active material layer of the electrode substrate.

[0139] In some embodiments, the viscosity of the lubricant is 10000 mPa.s to 150000 mPa.s; the viscosity of the lubricant is within the above range, which is conducive to the formation of a relatively thin lithium film layer after calendering; especially for the case where the lubricant covers the surface of the lithium material before calendering, the viscosity of the lubricant is within the above range, which is convenient for forming a thin and uniformly covered lubricant layer on the surface of the lithium material, and is also conducive to the formation of a relatively thin lithium film layer after calendering, thereby making it easier for the lithium film layer to be laminated with the electrode substrate, thereby improving the bonding strength between the lithium film layer and the electrode substrate.

[0140] Regarding the specific selection, size parameters, and ligands of lubricating oil and inorganic particles in the lubricant, please refer to the above content and will not be repeated here.

[0141] The present application also provides a method for preparing a lubricant, comprising: mixing lubricating oil with inorganic particles.

[0142] Among them, regarding the specific selection of lubricating oil and inorganic particles in the lubricant, size parameters, ligands and other related contents, please refer to the above content and will not be repeated here.

[0143] In some embodiments, the lubricating oil and the inorganic particles are mixed by stirring or segmented stirring for 1-10 hours to allow the inorganic particles to be fully dispersed in the lubricating oil.

[0144] The lithium-supplementing electrode can be used to prepare a battery 100. The prepared battery 100 has high cycle performance and low low-temperature resistance. The battery 100 can be used as a power source for electrical devices.

[0145] Next, one or more embodiments will be described in more detail with reference to the following examples. Of course, these examples do not limit the scope of one or more embodiments.

[0146] Experimental example

[0147] (1) Preparation of positive electrode sheet:

[0148] Lithium iron phosphate, conductive agent Super P and binder polyvinylidene fluoride (PVDF) in a mass ratio of 95:3:2 were mixed in a solvent N-methylpyrrolidone (NMP) to prepare a positive electrode active slurry with a solid content of 50 wt%.

[0149] The positive electrode active slurry was coated on the current collector aluminum foil (thickness of 13 μm) and dried at 85°C for 4 hours, then cold pressed, and then trimmed and cut into pieces, and dried at 85°C under vacuum conditions for 4 hours to obtain a positive electrode sheet, wherein the thickness of the single-sided positive electrode active material layer was 200 μm.

[0150] (2) Preparation of negative electrode sheet:

[0151] Graphite, conductive agent Super P and binder polytetrafluoroethylene (PTFE) in a mass ratio of 95:2:3 were mixed in a solvent N-methylpyrrolidone (NMP) to prepare a negative electrode active slurry with a solid content of 50 wt%.

[0152] The negative electrode active slurry was coated on the current collector copper foil (thickness of 8 μm) and dried at 85°C for 4 hours, then cold pressed, and then trimmed and cut into pieces, and dried at 85°C under vacuum conditions for 4 hours to obtain the negative electrode sheet substrate; wherein, the thickness of the single-sided negative electrode active material layer was 150 μm.

[0153] A lubricant is evenly applied to two opposing surfaces of a 0.8 mm thick lithium material in the thickness direction using a coating machine, resulting in a 2.5 μm thick lubricant layer covering both opposing surfaces. The lithium material is then placed between a first and a second calendering roller to form a lithium film. The rotation of the first and second calendering rollers peels the lithium film from the calendering rollers and transfers it to the negative electrode substrate, producing the negative electrode sheet.

[0154] The specific composition and related parameters of the lubricant are shown in Table 1; the surface linear speeds of the first calendering roller and the second calendering roller are shown in Table 2.

[0155] (3) Preparation of electrode assembly:

[0156] The separator is made of PP (polypropylene) and has a thickness of 16 μm. The negative electrode sheet, the first separator, the positive electrode sheet, and the second separator are stacked and wound to form an electrode assembly.

[0157] (4) Preparation of battery cells:

[0158] The electrode assembly is welded to its tabs, placed in a housing, and injected with electrolyte (the electrolyte is a 1M lithium hexafluorophosphate EC / DMC (1:1 vol%) solution). The battery then undergoes vacuum packaging, standing, formation, and shaping processes to obtain a battery cell.

[0159] Table 1 Specific composition and related parameters of lubricants

[0160] In Table 1, “ / ” means that there is no corresponding parameter.

[0161] Table 2 Surface linear speed of the first calendering roller and the second calendering roller

[0162] The performance of the negative electrode sheets and battery cells prepared in the examples and comparative examples was tested:

[0163] (1) Coverage rate between lithium film layer and negative electrode substrate

[0164] The calculation formula for the coverage rate of the lithium film layer and the negative electrode substrate is: M = 1-(A1 / A0) × 100%, where A1 is the mass of the lithium film layer not transferred to the negative electrode substrate, and A0 is "the total mass of the lithium film layer on the calendering roller before the lithium film layer is transferred to the negative electrode substrate."

[0165] (2) Wetting performance of negative electrode to electrolyte

[0166] 0.5 mL of electrolyte (the electrolyte is a 1 M lithium hexafluorophosphate EC / DMC (1:1 vol%) solution) was added dropwise onto the surface of the metal lithium film of the negative electrode plates prepared in Examples 1 to 19 and Comparative Examples 1 to 4. The surface metal lithium film gradually undergoes a lithium insertion reaction with the negative electrode active material. A CCD camera (100X) was used to observe the time it takes for the surface metal lithium film to completely fuse with the negative electrode active material. When there is no obvious solid metal lithium on the surface of the negative electrode plate, the time is recorded as the infiltration time of the negative electrode plate.

[0167] (3) Low temperature resistance of battery cells

[0168] At 25°C, first charge a battery cell to 3.65V at a constant current of 0.5C. Then discharge it to 2.5V at a constant current of 0.5C. The discharge capacity is Cn. Then, at -25°C, discharge the battery cell by 0.5Cn at a constant current of 1C. The battery capacity is now 0.5Cn. Simultaneously measure the current U and voltage I of the battery cell at this point. Calculate the battery cell resistance DCR = U / I.

[0169] (4) Cycling performance of battery cells

[0170] At 25°C, the battery cell is first charged to 3.65V at a constant current of 0.5C and then discharged to 2.5V at a constant current of 0.5C. This constitutes one charge-discharge cycle, and the discharge capacity is the discharge capacity of the first cycle. The battery cell is subjected to 200 cycles of charge-discharge testing in this manner. The discharge capacity at the 200th cycle is measured and the post-cycle capacity retention of the battery cell is calculated using the following formula.

[0171] Capacity retention rate of a battery cell after 200 cycles (%) = [discharge capacity at the 200th cycle / discharge capacity at the 1st cycle] × 100%.

[0172] The performance of the negative electrode sheet and the battery cell are shown in Table 3.

[0173] Table 3 Performance of negative electrode sheets and battery cells

[0174] FIG7 is a photograph of the lithium film layer prepared in Example 1, and FIG8 is a photograph of the lithium film layer prepared in Comparative Example 1.

[0175] As can be seen from FIG7 , in the lithium film layer prepared in Example 1, there are stripe gaps on the surface of the lithium film layer, indicating that the lithium film layer prepared in Example 1 has more points at which it can be combined with the negative electrode substrate, which can make the bonding ability between the lithium film layer and the negative electrode substrate stronger.

[0176] As can be seen from Figure 8, in the lithium film layer prepared in Comparative Example 1, the surface of the lithium film layer is smooth and has no stripe gaps, indicating that the lithium film layer prepared in Comparative Example 1 has few points at which it can be combined with the negative electrode substrate, which in turn leads to poor bonding ability between the lithium film layer and the negative electrode substrate.

[0177] It can be seen from Table 3 that in the negative electrode sheet prepared in Example 1, the coverage rate of the lithium film layer and the negative electrode sheet substrate can reach 92%, and in the negative electrode sheet prepared in Comparative Example 1, the coverage rate of the lithium film layer and the negative electrode sheet substrate is only 8%; in combination with Figures 7, 8 and Table 3, it can be seen that the scheme of Example 1 can make the lithium film layer effectively laminated with the negative electrode sheet substrate, while the scheme of Comparative Example 1 cannot make the lithium film layer and the negative electrode sheet substrate effectively laminated; This shows that: the method of "having a lubricant containing inorganic particles between the lithium material and the calendering roller, and calendering the lithium material by asynchronous rolling" can make the coverage rate between the lithium film layer obtained after calendering and the negative electrode sheet substrate higher.

[0178] As can be seen from Table 3, the coverage rate of the lithium film layer and the negative electrode sheet substrate in the battery cells prepared in Examples 1 to 19 and the capacity retention rate of the battery cells are higher than those in the battery cells prepared in Comparative Examples 1 to 4; the wetting time of the negative electrode sheets prepared in Examples 1 to 19 is lower than that of the negative electrode sheets prepared in Comparative Examples 3 to 4, and the low-temperature resistance of the battery cells prepared in Examples 1 to 19 is lower than that of the battery cells prepared in Comparative Examples 3 to 4; this indicates that the method of "having a lubricant containing inorganic particles between the lithium material and the calendering roller and calendering the lithium material by asynchronous rolling" can make the coverage rate between the lithium film layer obtained after calendering and the negative electrode sheet substrate higher, the obtained negative electrode sheet has better electrolyte wetting performance, and the obtained battery cell has higher capacity retention rate and better low-temperature performance.

[0179] From the comparison of Examples 1 to 5, it can be seen that the ratio of the mass of the lubricating oil to the "total mass of the spherical particles and the flaky particles" can further affect the coverage rate of the lithium film layer and the negative electrode sheet substrate and the capacity retention rate of the battery cell; when the ratio of the mass of the lubricating oil to the "total mass of the spherical particles and the flaky particles" is (30-80): (20-70), the coverage rate of the lithium film layer and the negative electrode sheet substrate can be higher and the capacity retention rate of the battery cell can be higher.

[0180] From the comparison between Example 1 and Examples 6 to 8, it can be seen that the volume average particle size D of the spherical particles is V 50 can further affect the coverage rate of the lithium film layer and the negative electrode substrate and the capacity retention rate of the battery cell; when the volume average particle size D V 50≤1μm, it is beneficial to further improve the coverage rate of the lithium film layer and the negative electrode substrate and the capacity retention rate of the battery cell; further, when the volume average particle size D of the spherical particles is V When the thickness is 50≤500nm, it is beneficial to further improve the coverage rate of the lithium film layer and the negative electrode substrate and the capacity retention rate of the battery cell.

[0181] From the comparison between Example 1 and Examples 9-10, it can be seen that the volume average particle size D of the flaky particles is V 50 can further affect the coverage rate of the lithium film layer and the negative electrode substrate and the capacity retention rate of the battery cell.

[0182] From the comparison between Example 1 and Examples 11 to 12, it can be seen that when the mass proportion of lubricating oil in the lubricant is the same, the mass ratio of spherical particles and flaky particles is 1:(1 to 10), which can make the coverage rate of the lithium film layer and the negative electrode substrate higher and the capacity retention rate of the battery cell higher.

[0183] From the comparison between Example 1 and Examples 13 to 15, it can be seen that the lubricating oil in the lubricant is selected from white oil or PAO, the spherical particles in the lubricant are graphite powder or sulfur powder, and the flaky particles in the lubricant are graphite powder or silicon powder, all of which can make the coverage rate of the lithium film layer and the negative electrode plate substrate higher and the capacity retention rate of the battery cell higher.

[0184] From the comparison between Example 1 and Examples 16 to 19, it can be seen that the ratio of the rotational speed of the first working roller to the rotational speed of the second working roller can further affect the coverage rate of the lithium film layer and the negative electrode sheet substrate and the capacity retention rate of the battery cell; when the ratio of the rotational speed of the first working roller to the rotational speed of the second working roller is (0.03 to 0.1):1, it is beneficial to further improve the coverage rate of the lithium film layer and the negative electrode sheet substrate and the capacity retention rate of the battery cell.

[0185] The embodiments described above are part of the embodiments of the present application, rather than all of the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

Claims

1. A method for preparing a lithium-supplementing electrode, the lithium-supplementing electrode comprising an electrode substrate, wherein: include: The lithium material is rolled using a rolling roller in an asynchronous rolling manner, and a lubricant is provided between the lithium material and the rolling roller; Laminating the rolled lithium material onto the surface of the pole piece substrate; Wherein, the lubricant includes lubricating oil and inorganic particles dispersed in the lubricating oil.

2. The preparation method according to claim 1, wherein The mass ratio of the lubricating oil to the inorganic particles is (30-80):(20-70).

3. The preparation method according to claim 1 or 2, wherein The inorganic particles include first particles, the volume average particle size D of the first particles is V 50≤1μm; Optionally, the volume average particle size D of the first particles is V 50≤500nm.

4. The preparation method according to claim 3, wherein The first particles are spherical, and the inorganic particles further include second particles, the second particles are flake-shaped, and the volume average particle size D of the second particles is V 50: 1μm~20μm; Optionally, the volume average particle size D of the second particles is V 50 is 2μm~7μm.

5. The preparation method according to claim 4, wherein: The mass ratio of the second particles to the first particles is (1-10):

1.

6. The preparation method according to any one of claims 1 to 5, wherein: The viscosity of the lubricant is 10000mpa.s to 150000mpa.s; Optionally, the viscosity of the lubricant is 30000mPa.s to 100000mPa.s.

7. The preparation method according to any one of claims 1 to 5, wherein: The inorganic particles contain at least one of carbon, silicon and sulfur; Optionally, the material of the inorganic particles is selected from at least one of carbon, silicon and sulfur; Optionally, the inorganic particles are conductive particles.

8. The preparation method according to any one of claims 1 to 5, wherein: The lubricating oil comprises at least one of a resin and a hydrocarbon lubricating oil; Optionally, the resin is selected from at least one of a polyether resin and an epoxy resin; Optionally, the hydrocarbon lubricant is at least one of poly-α-olefin lubricant, white oil and kerosene.

9. The preparation method according to any one of claims 1 to 5, wherein: The ratio of the surface linear speeds of the two calendering rollers is (0.03-0.1):1; Optionally, the surface linear speeds of the two calendering rollers are 1 m / min to 50 m / min and 2 m / min to 100 m / min, respectively.

10. A lithium supplement electrode, wherein: The lithium supplement pole piece comprises a pole piece substrate and a lithium film layer located on the surface of the active material layer of the pole piece substrate; Wherein, the lithium film layer has a plurality of grooves and / or a plurality of cracks.

11. The lithium supplement electrode according to claim 10, wherein: The surface of the lithium film layer has a stripe pattern formed by the grooves and / or the cracks.

12. The lithium supplement electrode according to claim 10 or 11, wherein: Along the direction from the pole piece substrate to the lithium film layer, the lithium film layer includes a lithium material layer and a lubricant layer arranged in sequence; wherein the thickness of the lithium material layer is 1 μm to 15 μm; the lubricant layer includes a lubricant, and the lubricant includes lubricating oil and inorganic particles dispersed in the lubricating oil.

13. A lubricant, wherein: The lubricant includes lubricating oil and inorganic particles dispersed in the lubricating oil; The mass ratio of the lubricating oil to the inorganic particles is (30-80):(20-70).

14. The lubricant according to claim 13, wherein The inorganic particles include first particles, the volume average particle size D of the first particles is V 50≤1μm; Optionally, the volume average particle size D of the first particles is V 50≤500nm; Optionally, the first particles are spherical, the inorganic particles further include second particles, the second particles are flake-shaped, and the volume average particle size D of the second particles is V 50: 1μm~20μm; Optionally, the mass ratio of the second particles to the first particles is (1-10):1; Optionally, the viscosity of the lubricant is 10000 mPa.s to 150000 mPa.s.

15. A battery, wherein: The battery comprises the lithium supplement electrode as described in any one of claims 10 to 12.

16. An electrical device, wherein: The electrical device comprises the battery according to claim 15.

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