Battery cell, related device, system and charging network

Abstract

The invention relates to the technical field of batteries, and provides a battery monomer, a related device, a system and a charging network. The battery monomer provided by the invention comprises a positive electrode plate, the positive electrode plate comprises a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector, the positive electrode film layer comprises a positive electrode active material, and the positive electrode active material comprises positive electrode active material particles and a coating material, the material discontinuously coats the surfaces of positive active material particles to form a coating layer, and the coating material comprises metal phosphate and a carbon material. In the battery monomer provided by the invention, the positive pole piece contains the positive active material with a specific structure and specific components, so that the positive active material is stable in structure and relatively low in interface impedance, and the positive pole piece is endowed with relatively high electron and ion transmission rate, so that the battery monomer shows excellent cycle performance.

Description

Technical Field

[0001] This application belongs to the field of battery technology, and in particular relates to a battery cell, related devices, systems and charging networks. Background Technology

[0002] The statements herein are intended to provide background information in connection with this application and do not necessarily constitute prior art.

[0003] In recent years, with the increasingly wide application of rechargeable batteries, they have been widely used in energy storage power systems such as hydropower, thermal power, wind power, and solar power plants, as well as in various fields such as power tools, electric bicycles, electric motorcycles, and electric vehicles. Due to the significant progress made in the battery field, higher performance requirements have been placed on rechargeable batteries.

[0004] As the active ion donor in secondary batteries, the positive electrode active material has a significant impact on the energy density and capacity cycle retention of the battery. To further improve the cycle life of individual battery cells, higher requirements are being placed on the positive electrode active material. Summary of the Invention

[0005] The purpose of this application is to provide a battery cell, related devices, systems and charging networks, which aim to solve the problem of unsatisfactory cycle performance of battery cells.

[0006] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows:

[0007] In a first aspect, this application provides a battery cell including a positive electrode sheet, the positive electrode sheet including a positive current collector and a positive electrode film layer disposed on at least one side of the positive current collector, the positive electrode film layer including a positive electrode active material, the positive electrode active material including positive electrode active material particles and a coating material, the coating material being discontinuously coated on the surface of the positive electrode active material particles to form a coating layer, the coating material including metal phosphate and carbon material.

[0008] In this application's technical solution, the positive electrode active material comprises positive electrode active material particles and a coating material. The coating material includes metal phosphates and carbon materials. Metal phosphates have high ionic conductivity and can serve as lithium-ion transport channels and carriers. Therefore, metal phosphates can provide more lithium-ion transport channels for the positive electrode active material particles, thereby enhancing their ionic conductivity. Carbon materials have high electrical conductivity; therefore, coating the surface of the positive electrode active material particles with carbon materials can construct a good conductive network on the particle surface. This not only provides an effective transport path for electrons but also reduces the contact resistance between the particles, allowing for rapid electron transport. Thus, the coating material, including metal phosphates and carbon materials, improves the ionic and electronic conductivity of the positive electrode active material particles, enabling rapid electron and ion transport within the positive electrode, thereby contributing to improved battery cell capacity cycle retention. In addition, the coating material is coated on the surface of the positive electrode active material particles in a discontinuous form, which can suppress the dissolution of active ions contained in the positive electrode active material particles to a certain extent, so that the positive electrode active material particles have high structural stability. This makes it less likely to affect the lithium-ion storage and deintercalation ability of the positive electrode active material particles, thereby effectively improving the capacity cycle retention rate of the battery cell.

[0009] In some embodiments, the coating material has a core-shell structure, wherein the core material of the core-shell structure is a metal phosphate and the outer shell material of the core-shell structure is a carbon material.

[0010] The coating material has a core-shell structure, specifically carbon material coating the surface of metal phosphate to form a shell layer, thereby effectively increasing the contact effect between metal phosphate and carbon material, improving the uniformity of the conductivity of metal phosphate, thereby reducing the interfacial polarization of the positive electrode active material and reducing the interfacial impedance of the positive electrode active material.

[0011] In some embodiments, the covering material satisfies at least one of the following features (1) to (4):

[0012] (1) The particle size of the coating material Dv250 is less than 300nm;

[0013] (2) The thickness of the shell is 1nm-5nm;

[0014] (3) The mass percentage of carbon materials in the coating material is 1-8 wt%;

[0015] (4) The metals corresponding to the metal phosphates include at least one of iron, nickel, cobalt and manganese.

[0016] By controlling the type of metal phosphate, the content of each component, the thickness of the carbon material shell, and the particle size of the coating material within the above-mentioned range, the coating material can fully exert its performance in improving the ionic conductivity and ionic conductivity of the positive electrode active material particles. This helps to reduce the interfacial impedance of the positive electrode active material, thereby providing a positive effect on the cycle performance of the battery cell.

[0017] In some embodiments, the coating material is coated in an island-like manner onto at least a portion of the surface of the positive electrode active material particles to form a coating layer.

[0018] Island-like coating means that the coating material is not completely coated on the surface of the positive electrode active material particles, so that the diffusion of lithium ions is not easily hindered. As a result, lithium ions have a high migration rate, and the battery cell exhibits excellent cycle performance.

[0019] In some embodiments, the thickness of the coating layer is <300 nm.

[0020] In some embodiments, the thickness of the coating layer is 20nm-100nm.

[0021] By controlling the thickness of the coating layer within the above-mentioned range, the surface of the positive electrode active material particles has a coating material of suitable thickness. This not only helps to improve the ion conduction and electron conduction capabilities of the positive electrode active material particles, but also gives lithium ions a shorter migration path, which helps lithium ions to migrate quickly in the battery cell.

[0022] In some embodiments, the mass ratio of positive electrode active material particles to coating material is 95-80:5-20.

[0023] By controlling the mass ratio of positive electrode active material particles to coating material within the above range, the coating material forms a coating layer of suitable thickness on the positive electrode active material particles, thereby helping lithium ions maintain a high migration rate.

[0024] In some embodiments, the D of the positive electrode active material particles v1 The particle size of 50 particles ranges from 3μm to 15μm.

[0025] Controlling the D of positive electrode active material particles v1 With a particle size of 50 mm within the above range, the coating material with a core-shell structure is more easily distributed on the surface of the positive electrode active material particles to form a coating layer of suitable thickness, thus making it less likely to affect the migration rate of lithium ions.

[0026] In some embodiments, the positive electrode also contains a lithium replenishing agent, the decomposition voltage of which is lower than the standard decomposition voltage of the lithium replenishing agent.

[0027] In the positive electrode, the surface of the positive active material is coated with a core-shell structured coating material. The shell of the coating material is a carbon material with good conductivity. Therefore, when the lithium replenisher comes into contact with the positive active material, the lithium replenisher can make full contact with the carbon material, thereby effectively improving the conductivity of the lithium replenisher. The carbon material can also act as a catalyst to catalyze the delithiation of the lithium replenisher. Thus, the lithium replenisher achieves delithiation under conditions lower than its standard decomposition voltage, resulting in an abundance of lithium ions in the battery cell system. This helps to improve the overall electrochemical performance of the battery.

[0028] In some embodiments, the mass ratio of lithium supplement to positive electrode active material is 0-10:99-90.

[0029] Secondly, this application provides a method for preparing a battery cell, comprising the following steps:

[0030] Metal phosphates are mixed with a carbon source and then sintered to obtain a coating material.

[0031] The positive electrode active material is obtained by discontinuously coating the surface of the positive electrode active material particles with the coating material.

[0032] A positive electrode slurry containing a positive electrode active material is prepared, and the positive electrode slurry is coated on at least one surface of a positive electrode current collector to form a positive electrode film layer, thereby obtaining a positive electrode sheet;

[0033] The positive and negative electrode plates are assembled to obtain a single battery cell.

[0034] In some embodiments, the sintering conditions include sintering at 700°C-800°C for 5-10 hours under a protective atmosphere.

[0035] By controlling the sintering conditions within the above range, it is possible to obtain a coating material with a core-shell structure.

[0036] In some embodiments, the step of discontinuously coating the surface of the positive electrode active material particles with the coating material includes: mixing the coating material with the positive electrode active material particles and sintering at 500°C-600°C for 4-8 hours.

[0037] By adopting the above steps, a positive electrode active material with high ionic conductivity and electronic conductivity can be obtained, and the metal ions contained in the positive electrode active material are not easily dissolved.

[0038] In some embodiments, a lithium supplement agent is added to the prepared positive electrode slurry, and the mass ratio of the lithium supplement agent to the positive electrode active material is 1-10:99-90.

[0039] By controlling the mass ratio of lithium replenishing agent to positive electrode active material within the above range, the loss of active lithium in the battery cell during the first charge can be compensated, thereby effectively improving the electrochemical performance of the battery cell.

[0040] Thirdly, this application provides a battery device including multiple battery cells of the above embodiments.

[0041] Fourthly, this application provides an energy storage device, including multiple battery cells or multiple battery devices according to the above embodiments.

[0042] Fifthly, this application provides an energy storage system, including a power conversion device and an energy storage device according to the above embodiments, wherein the power conversion device is used to electrically connect a power generation device and the energy storage device.

[0043] Sixthly, this application provides an electrical device, including a battery cell, a battery device, an energy storage device, or an energy storage system as described in the above embodiments, wherein the battery cell or the battery device is used to store or provide electrical energy.

[0044] In a seventh aspect, this application provides a charging network, including a charging pile and an energy storage device or an energy storage system as described in the above embodiments, wherein the energy storage device is used to provide electrical energy to the charging pile. Attached Figure Description

[0045] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0046] Figure 1 This is a schematic diagram of the positive electrode active material structure provided in the embodiments of the present invention / application;

[0047] Figure 2 This is an exploded view of the battery provided in the embodiments of the present invention / application;

[0048] Figure 3 This is an exploded view of a battery cell provided in the embodiments of the present invention / application.

[0049] The following are the labeling elements in the figure:

[0050] 100. Battery;

[0051] 10. Box body; 11. First box body; 12. Second box body;

[0052] 20. Battery cell modules;

[0053] 30. Battery cell; 31. Housing; 32. Electrode assembly; 33. Cover plate;

[0054] 4. Positive electrode active material; 41. Positive electrode active material particles; 42. Coating material;

[0055] 421. Metal phosphates; 422. Carbon materials. Detailed Implementation

[0056] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0057] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0058] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0059] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0060] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0061] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0062] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0063] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0064] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0065] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order; for example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0066] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0067] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0068] Unless otherwise specified, the following terms have the following meanings. Any undefined terms have their technically accepted meanings.

[0069] Typically, a battery cell includes a positive electrode, a negative electrode, an electrolyte, and a separator. During the charging and discharging process, active ions move back and forth between the positive and negative electrodes, inserting and extracting. The electrolyte, acting as a conductor for the active ions, lies between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, primarily prevents short circuits while allowing the passage of active ions.

[0070] In the embodiments of this application, SEI film is short for "solid electrolyte interface", which refers to a solid electrolyte interface film with the characteristics of a solid electrolyte. That is, during the first charge and discharge process of a liquid lithium-ion battery, a passivation layer formed by the reaction between the electrode material and the electrolyte at the solid-liquid interface is formed and covers the surface of the negative electrode material.

[0071] In this embodiment of the application, the battery cell can be a secondary battery, which refers to a battery cell that can be recharged to activate the active materials and continue to be used after the battery cell has been discharged.

[0072] With the continued strong performance of the new energy vehicle market, the demand for power batteries is growing day by day. Developing power lithium-ion batteries with high energy density, stable structure, and high cycle stability has become an urgent need in the current market.

[0073] Spinel-type lithium nickel manganese oxide (LiMO) materials are favored by society among commercially available lithium-ion battery cathode active materials due to their advantages such as high capacity retention, cycle stability, low cost, and environmental friendliness. However, spinel-type LiMO is prone to transition metal ion dissolution during charge and discharge, such as manganese ion dissolution. Manganese ions deposit on the negative electrode surface and damage the SEI film, leading to increased battery impedance and capacity decay, thus hindering the large-scale application of LiMO materials.

[0074] Based on the above background, this application provides a battery cell that improves the cycle performance of the battery by improving the positive electrode active material contained in the positive electrode sheet, such as improving the battery's capacity cycle retention rate and interface resistance.

[0075] Next, we will provide a detailed introduction to the positive electrode, negative electrode, separator, and electrolyte components of a single battery cell.

[0076] [Positive electrode plate]

[0077] The positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector, the positive electrode film layer including a positive electrode active material.

[0078] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer can be disposed on either or both of the two opposite surfaces of the positive current collector.

[0079] In some embodiments, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0080] In some embodiments, the positive electrode active material includes positive electrode active material particles and a coating material, wherein the coating material is discontinuously coated on the surface of the positive electrode active material particles to form a coating layer, and the coating material includes metal phosphates and carbon materials.

[0081] Metal phosphates have high ionic conductivity and can serve as lithium-ion transport channels and carriers. Therefore, metal phosphates can provide more lithium-ion transport channels for positive electrode active material particles, thereby enhancing the ion migration rate of the positive electrode active material particles.

[0082] Carbon materials have high conductivity. Therefore, coating the surface of positive electrode active material particles with carbon materials can build a good conductive network on the surface of the positive electrode active material particles, providing an effective transport path for electrons. This not only reduces the contact resistance between positive electrode active material particles, but also reduces the interfacial resistance between metal phosphate and positive electrode active material particles, thereby reducing the resistive polarization of the positive electrode active material. In this way, electrons can be transported quickly between positive electrode active materials.

[0083] Therefore, carbon materials and metal phosphates are used as coating materials. In this way, a conductive path is formed between adjacent coating material particles through the contact of carbon materials, and there are also carbon materials between the metal phosphates and the positive electrode active material particles. In this way, the coating materials can improve the conductive network on the surface of the positive electrode active material particles, so that electrons and ions can be transported quickly in the positive electrode. This can effectively reduce the interfacial polarization of the positive electrode active material, reduce the interfacial impedance of the positive electrode active material, and make the battery cell have a better cycle capacity retention rate.

[0084] It is understood that discontinuous coating refers to a coating layer on the surface of the coated substrate that is not complete, continuous, and uninterrupted. In the embodiments of this application, when the coating material coats the positive electrode active material particles, the coating layer has interrupted, vacant, or discontinuous parts. Specifically, the coating material may be distributed in dispersed and isolated areas on the surface of the positive electrode active material particles, with uncoated blank areas between these areas.

[0085] The coating material is applied discontinuously to the surface of the positive electrode active particles, which can inhibit the dissolution of active ions contained in the particles to a certain extent, thus giving the particles higher structural stability. This keeps the number of active sites in the positive electrode that can participate in electrochemical reactions at a high level, minimizing the impact on the lithium-ion storage and deintercalation capabilities of the particles, thereby helping to improve the capacity cycle retention of the battery cell. Furthermore, the discontinuous coating means that there are gaps between some adjacent coating material particles. These gaps can serve as lithium-ion transport channels, minimizing spatial obstruction and facilitating faster lithium-ion transport, resulting in a higher capacity cycle retention rate for the battery cell.

[0086] In some embodiments, the coating material has a core-shell structure, wherein the core material of the core-shell structure is a metal phosphate and the outer shell material of the core-shell structure is a carbon material.

[0087] Please see Figure 1 The positive electrode active material 4 includes positive electrode active material particles 41 and coating material 42. The coating material 42 includes metal phosphate 421 and carbon material 422. The carbon material 422 coats the surface of the metal phosphate 421 to form a shell, thereby the coating material 42 has a core-shell structure.

[0088] Carbon material is coated onto the surface of metal phosphate to form a shell, effectively increasing the contact between the metal phosphate and the carbon material, thus improving the uniformity of the metal phosphate's conductivity. Therefore, coating the surface of the positive electrode active material particles with a core-shell structure means that carbon material is interspersed between the positive electrode active material particles and the metal phosphate, and adjacent coated material particles are in contact through the carbon material. This creates a more complete conductive network on the surface of the positive electrode active material particles, providing an excellent conductive environment. This reduces the interfacial polarization of the positive electrode active material, resulting in a lower interfacial impedance. This reduces energy loss during charging and discharging of the battery cell and helps improve the cycle capacity retention rate of the battery cell.

[0089] In some embodiments, the Dv250 particle size of the coating material is <300 nm. vThe 50 particle size designation refers to the particle size corresponding to a cumulative volumetric distribution percentage of 50% for the material, which can be determined using instruments and methods known in the art. For example, the Dv250 particle size of the coating material can be typical but not limiting values ​​such as 20 nm, 50 nm, 80 nm, 100 nm, 120 nm, 150 nm, 180 nm, 200 nm, 220 nm, 250 nm, 280 nm, and 290 nm.

[0090] Controlling the particle size of the coating material within the above-mentioned range, that is, keeping the particle size of the coating material at the nanometer level, is more conducive to coating the surface of the positive electrode active material particles and forming a coating layer.

[0091] In some embodiments, the Dv250 particle size of the coating material is 20nm-100nm. For example, the Dv250 particle size of the coating material can be typical but not limiting values ​​such as 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, and 100nm.

[0092] The fact that the particle size of the coating material is within the aforementioned range means that, under the same mass conditions, the coating material has as many particles as possible, which is more conducive to the coating material coating the surface of the positive electrode active material particles. Moreover, because the particle size of the coating material is within the aforementioned range, the coating material forms a coating layer of suitable thickness on the surface of the positive electrode active material particles, which helps lithium ions to migrate rapidly.

[0093] In some embodiments, the thickness of the housing is 1 nm to 5 nm. For example, the thickness of the housing can be a typical but non-limiting value such as 1 nm, 2 nm, 3 nm, 4 nm, or 5 nm.

[0094] By controlling the thickness of the casing within the aforementioned range, a good conductive environment can be formed on the surface of the metal phosphate, thereby reducing the polarization of the positive electrode activity and giving the positive electrode active material a lower interfacial impedance, thus providing a positive effect on the cycle performance of the battery cell.

[0095] In some embodiments, the carbon material accounts for 1-8 wt% of the coating material by mass. For example, the mass percentage of carbon material can be typical but not limiting values ​​such as 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%.

[0096] By controlling the carbon material content within the above range, a carbon material shell of suitable thickness can be formed on the surface of the metal phosphate. This not only improves the conductivity of the metal phosphate but also does not affect the lithium-ion transport path of the metal phosphate, giving the coating material high ion conductivity and electron conductivity.

[0097] In some embodiments, the metal corresponding to the metal phosphate includes at least one of iron, nickel, cobalt, and manganese.

[0098] These metal phosphates have good ionic conductivity, which can effectively improve the ionic conductivity of the positive electrode active material particles.

[0099] For example, metal phosphates include, but are not limited to, iron phosphate (FePO4), manganese phosphate (Mn3(PO4)2), cobalt phosphate (Co3(PO4)2), and nickel phosphate (Ni3(PO4)2).

[0100] In some embodiments, the coating material is coated in an island-like manner onto at least a portion of the surface of the positive electrode active material particles to form a coating layer.

[0101] Island coating refers to the distribution of multiple spaced island-shaped or dot-shaped coating layers on the surface of positive electrode active material particles. These multiple island-shaped or dot-shaped coating layers form a discontinuous coating layer. Island coating means that the coating material is coated on the surface of the positive electrode active material particles in a discontinuous form, which makes the diffusion of lithium ions less obstructed. As a result, lithium ions have a higher migration rate, and the battery cell exhibits excellent cycle performance.

[0102] In some embodiments, the thickness of the coating layer is <300 nm. For example, the thickness of the coating layer can be typical but not limiting values ​​such as 20 nm, 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 280 nm, 290 nm, 295 nm, etc.

[0103] Controlling the thickness of the coating layer to less than 300 nm means that the surface of the positive electrode active material particles has an appropriate thickness, which makes the migration path of lithium ions shorter, giving lithium ions a higher migration rate and playing a positive role in the cycle performance of the battery cell.

[0104] In some embodiments, the thickness of the coating layer is 20nm-100nm. For example, the thickness of the coating layer can be a typical but non-limiting value such as 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, etc.

[0105] By controlling the thickness of the coating layer within the above-mentioned range, the surface of the positive electrode active material particles has a coating material of suitable thickness. This not only helps to improve the ion conduction and electron conduction capabilities of the positive electrode active material particles, but also gives lithium ions a shorter migration path, enabling lithium ions to migrate quickly.

[0106] In some embodiments, the mass ratio of positive electrode active material particles to coating material is 95-80:5-20. For example, the mass percentage of positive electrode active material particles can be typical but not limiting values ​​such as 80, 82, 85, 88, 90, 92, 95, etc., and the mass percentage of coating material can be typical but not limiting values ​​such as 5, 8, 10, 12, 15, 18, 20, etc.

[0107] By controlling the mass ratio of positive electrode active material particles to coating material within the above range, after the positive electrode active material particles and coating material particles are combined, there is enough coating material to form a discontinuous coating on the surface of the positive electrode active material particles, and the coating layer is formed by a single layer of coating material particles. In this way, the coating layer formed on the surface of the positive electrode active material particles has an appropriate thickness, and lithium ions have a high migration rate, which helps to improve the cycle performance of the battery cell.

[0108] In some embodiments, the D of the positive electrode active material particles v1 50 particles have a diameter of 3μm-15μm. D v The 50 particle size designation refers to the particle size corresponding to a cumulative volume distribution percentage of 50% for the material, which can be determined using instruments and methods known in the art. For example, the D of positive electrode active material particles... v1 The particle size can be typical but not limited to values ​​such as 3μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, and 16μm.

[0109] Controlling the D of positive electrode active material particles v1 With a particle size of 50 mm within the above range, the coating material with a core-shell structure is more easily distributed on the surface of the positive electrode active material particles, forming a single-layer coating material particle coating layer, which does not easily affect the migration rate of lithium ions.

[0110] In some embodiments, the upper limit of the decomposition voltage of the positive electrode active material particles is ≥4.2V.

[0111] The upper limit decomposition voltage refers to the maximum applied voltage theoretically required to cause the electrolyte to decompose during electrolysis. In this application, the upper limit decomposition voltage refers to the maximum voltage value that ensures effective delithiation of the positive electrode active material particles.

[0112] Controlling the upper limit of the decomposition voltage to ≥4.2V not only makes the positive electrode active material more stable during charging and discharging, making it less prone to structural damage and side reactions, thus extending the battery's cycle life; it also means that the positive electrode active material can enable the battery cell to store more energy per unit volume or weight, thereby increasing the energy density of the battery cell.

[0113] For example, positive electrode active material particles include, but are not limited to, lithium nickel manganese oxide.

[0114] The operating voltage range of spinel lithium nickel manganese oxide is 3.5-4.95V (vs Li / Li + The {110} crystal planes of lithium nickel manganese oxide (LiMO) reduce stress accumulation and prevent particle breakage under stress. However, these planes are prone to manganese (Mn) leaching, leading to a decrease in positive electrode capacity and damage to the SEI film of the negative electrode. Therefore, in this embodiment, a core-shell structured coating material is discontinuously coated on the surface of lithium nickel manganese oxide, thereby effectively reducing Mn leaching. Furthermore, the core metal phosphate of this coating material provides a transport channel for lithium ions, thus enabling the coating material to reduce Mn leaching without hindering lithium ion migration, thereby improving the cycle performance of the battery cell.

[0115] During the first charge of a lithium-ion battery, the organic electrolyte undergoes reduction and decomposition on the surface of the negative electrode, such as graphite, forming a solid electrolyte interphase (SEI) film. This permanently consumes a significant amount of lithium from the positive electrode, resulting in a low coulombic efficiency during the first cycle and reducing the battery's capacity and energy density. Adding a lithium replenishing agent to the positive electrode can offset the irreversible lithium loss caused by the SEI film formation. However, due to the high decomposition voltage of these lithium replenishing agents, they are not compatible with most commercially available positive electrode materials.

[0116] In view of this, the embodiments of this application improve the positive electrode active material by attaching a core-shell structured coating material to the surface of the positive electrode active material particles. The shell of this coating material is a carbon material with good conductivity. Therefore, when the lithium replenisher comes into contact with the positive electrode active material, the lithium replenisher can fully contact the carbon material in the coating material, thereby effectively improving the conductivity of the lithium replenisher. Furthermore, the carbon material can also act as a catalyst to catalyze the delithiation of the lithium replenisher. Thus, the lithium replenisher achieves delithiation under conditions lower than its standard decomposition voltage, resulting in sufficient lithium ions in the battery cell, which helps to improve the overall electrochemical performance of the battery cell.

[0117] In some embodiments, the positive electrode film layer further comprises a lithium replenishing agent, the decomposition voltage of which is lower than the standard decomposition voltage of the lithium replenishing agent.

[0118] The standard decomposition voltage refers to the standard potential difference required for a lithium supplement to undergo a decomposition reaction under specific conditions. In the embodiments of this application, the standard decomposition voltage refers to the energy threshold required for electron transfer during the decomposition process of the lithium supplement. That is, when the voltage applied to the lithium supplement reaches or exceeds this standard decomposition voltage, the lithium supplement will begin to undergo a decomposition reaction, achieving delithiation.

[0119] In the positive electrode film, the lithium replenishing agent mainly contacts the positive electrode active material, which is composed of positive electrode active material particles and a coating material discontinuously distributed on the surface of the positive electrode active material particles. The coating material contains a carbon material shell, which can build a complete conductive network on the surface of the positive electrode active material. This can effectively improve the conductive environment of the positive electrode sheet, thereby reducing the impedance at the interface between the positive electrode active material and the lithium replenishing agent. Moreover, the carbon material can also act as a catalyst for the lithium replenishing agent, which significantly reduces the decomposition voltage of the lithium replenishing agent to below its standard decomposition voltage.

[0120] Since the positive electrode film also includes a conductive agent, the conductive agent comes into contact with the carbon material on the surface of the positive electrode active material, thus constructing an excellent conductive network in the positive electrode sheet. This further helps to improve the conductive environment of the lithium supplement and reduce the decomposition voltage of the lithium supplement.

[0121] Because the positive electrode active material used in any of the above embodiments is employed, the lithium replenisher can perform delithiation more effectively than the positive electrode active material particles. Thus, the lithium replenisher acts as a "sacrificial agent" during the formation stage, releasing as many lithium ions as possible in one go to replenish the irreversible lithium ions consumed during the formation of the SEI film at the negative electrode. This maintains an ample supply of lithium ions within the battery cell and improves the battery's electrochemical performance. Furthermore, the lithium replenisher's ability to delithigate as much lithium as possible during the formation stage also reduces subsequent cycle expansion of the battery cell. Moreover, since the carbon material in the positive electrode active material can also act as a catalyst for the lithium replenisher, a larger amount of lithium replenisher can be added to the battery cell to improve its cycle capacity. In addition, since no additional lithium replenisher catalyst needs to be introduced into the battery cell, the energy density of the battery cell can also be increased.

[0122] In some embodiments, the mass ratio of lithium supplement to positive electrode active material is 0-10:99-90. Exemplarily, the mass percentage of lithium supplement can be a typical but not limiting value such as 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10. The mass percentage of positive electrode active material can be a typical but not limiting value such as 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99.

[0123] The lithium replenishing agent undergoes delithiation during battery formation, releasing as many lithium ions as possible in one go to replenish the irreversible lithium ions consumed during the formation of the SEI film at the negative electrode, thereby maintaining an ample supply of lithium ions within the battery system. In one embodiment, a portion of the lithium replenishing agent is not delithiated during battery formation; the remaining portion continues to delithiate during subsequent charge and discharge processes to release sufficient lithium ions, achieving efficient lithium replenishment. In another embodiment, the lithium replenishing agent undergoes complete delithiation during formation, contributing ample lithium ions and achieving efficient lithium replenishment.

[0124] Most lithium replenishing agents undergo delithiation during the formation stage of the battery cell, which allows the gas generated by the delithiation to be released during this stage. This gas is then extracted during the second sealing process after formation, which not only replenishes the active lithium lost due to the formation of the SEI film but also reduces the subsequent cycle expansion of the battery cell.

[0125] In some embodiments, the positive electrode film layer may optionally include a binder. As an example, the binder may include at least one selected from polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0126] In some embodiments, the positive electrode film may optionally include a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0127] [Negative electrode plate]

[0128] The negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector, the negative electrode film layer including a negative electrode active material.

[0129] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode film layer can be disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0130] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0131] In some embodiments, the negative electrode active material may be a negative electrode active material known in the art for use in battery cells. As an example, the negative electrode active material may include, but is not limited to, one or more of carbon materials (e.g., carbon materials include at least one of natural graphite, artificial graphite, soft carbon, and hard carbon), silicon-based materials, tin-based materials, and lithium titanate.

[0132] In some embodiments, the negative electrode film layer may optionally include an adhesive. The adhesive may be selected from at least one of styrene-butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid, and carboxymethyl chitosan.

[0133] In some embodiments, the negative electrode film may optionally include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0134] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose).

[0135] In some embodiments, the negative electrode sheet can be prepared by dispersing the above-mentioned components for preparing the negative electrode sheet, such as negative electrode active material, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto the negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0136] [Electrolytes]

[0137] The electrolyte acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific limitations on the type of electrolyte; it can be selected according to requirements. For example, the electrolyte can be liquid, gel-like, or entirely solid.

[0138] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0139] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium fluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, lithium tetrafluorooxalate phosphate, N-dialkylpyrrolidine onium lithium salt, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, and N-ethylpyrrolidine onium lithium tetrafluoroborate.

[0140] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0141] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0142] [Isolation membrane]

[0143] This application does not impose any particular restrictions on the type of separator membrane; any known porous separator membrane with good chemical and mechanical stability can be selected.

[0144] In some embodiments, the material of the separator can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0145] In some embodiments, the positive electrode, negative electrode, and separator described above can be fabricated into an electrode assembly by a winding process or a stacking process.

[0146] In some embodiments, a single battery cell may include an outer packaging. This outer packaging may be used to encapsulate the electrode assembly and electrolyte described above.

[0147] The second aspect of this application provides a method for preparing a battery cell, comprising the following steps:

[0148] Step S10: Mix the metal phosphate with the carbon source and then sinter it to obtain the coating material;

[0149] Step S20: The coating material is discontinuously coated onto the surface of the positive electrode active material particles to obtain the positive electrode active material;

[0150] Step S30: Prepare a positive electrode slurry containing a positive electrode active material, and coat the positive electrode slurry onto at least one surface of the positive electrode current collector to form a positive electrode film layer, thereby obtaining a positive electrode sheet;

[0151] Step S40: Assemble the positive electrode and the negative electrode to obtain a single battery cell.

[0152] The battery cell preparation method provided in this application involves mixing and sintering a metal phosphate with a carbon source, causing the carbon source to form a carbon material that coats the surface of the metal phosphate, thus obtaining a core-shell structured coating material. This coating material is then discontinuously coated onto the surface of positive electrode active material particles to obtain the positive electrode active material. A positive electrode sheet containing the positive electrode active material is then prepared, and finally, the positive and negative electrode sheets are assembled, thereby effectively producing a battery cell with the performance described in the above embodiments. Furthermore, the battery cell preparation method is simple, reliable, and controllable, which is beneficial for its widespread application.

[0153] In some embodiments, in step S10, the carbon source includes, but is not limited to, at least one of conductive carbon black, acetylene black, carbon nanotubes, Ketjen black, graphene oxide, polyvinylidene fluoride, glucose, sucrose, starch, citric acid, lauric acid, polypropylene, hydroxyethyl cellulose, and polycarbonate.

[0154] In some embodiments, the selection of metal phosphate in step S10 is as described above and will not be repeated here.

[0155] In some embodiments, before mixing the metal phosphate with the carbon source in step S10, the metal phosphate is further refined. The refining process may include, but is not limited to, ball milling. The Do of the metal phosphate after refining is... v3 50 Particle size <300nm, such as refined metal phosphate D v3 The particle size of 50 particles ranges from 20nm to 100nm.

[0156] In some embodiments, in step S10, the sintering conditions include sintering at 700°C-800°C for 5-10 hours under a protective atmosphere. Exemplarily, the first sintering temperature can be a typical but not limiting value such as 700°C, 710°C, 720°C, 730°C, 740°C, 750°C, 760°C, 770°C, 780°C, 790°C, or 800°C. The first sintering time can be a typical but not limiting value such as 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, or 10 hours.

[0157] During the sintering process, carbon source carbonizes to form carbon material that coats the surface of metal phosphate to form a shell, thus obtaining a core-shell structured coating material.

[0158] In some embodiments, the mixing conditions in step S10 are: a rotational speed of 800 rpm to 1500 rpm and a mixing time of 10 min to 60 min. For example, the rotational speed can be typical but not limiting values ​​such as 800 rpm, 900 rpm, 1000 rpm, 1100 rpm, 1200 rpm, 1300 rpm, 1400 rpm, and 1500 rpm. The mixing time can be typical but not limiting values ​​such as 10 min, 20 min, 30 min, 40 min, 50 min, and 60 min.

[0159] In some embodiments, step S20, the step of discontinuously coating the surface of the positive electrode active material particles with the coating material, includes: mixing the coating material with the positive electrode active material particles and sintering at 500°C-600°C for 4-8 hours. Exemplarily, the second sintering temperature can be a typical but not limiting value such as 500°C, 510°C, 520°C, 530°C, 540°C, 550°C, 560°C, 570°C, 580°C, 590°C, or 600°C. The second sintering time can be a typical but not limiting value such as 4 hours, 5 hours, 6 hours, 7 hours, or 8 hours.

[0160] During the sintering process, the coating material coats the surface of the positive electrode active material particles to form a discontinuous coating layer.

[0161] In some embodiments, in step S30, the positive electrode slurry is obtained using methods well known in the art, and can be prepared using the following methods;

[0162] The positive electrode active material, conductive agent, and binder are dispersed in a solvent to form a positive electrode slurry.

[0163] The selection of conductive agents and binders has been described above and will not be repeated here.

[0164] In some embodiments, in step S30, a lithium supplement agent is further added to the prepared positive electrode slurry, and the mass ratio of the lithium supplement agent to the positive electrode active material is 1-10:99-90. Exemplarily, the mass percentage of the lithium supplement agent can be a typical but non-limiting value such as 1, 2, 3, 4, 5, 6, 7, 8, 9, 10. The mass percentage of the positive electrode active material can be a typical but non-limiting value such as 90, 91, 92, 93, 94, 95, 96, 97, 98, 99.

[0165] Since the positive electrode active material is composed of positive electrode active material particles and a coating material discontinuously distributed on the surface of the positive electrode active material particles, and the coating material contains a carbon shell, it can improve the conductive network on the surface of the positive electrode active material. Furthermore, after the positive electrode active material comes into contact with the conductive agent, the conductive agent comes into contact with the carbon material on the surface of the positive electrode active material, thus constructing an excellent conductive network in the positive electrode sheet. In the positive electrode film layer, the lithium supplement mainly contacts the carbon material in the positive electrode active material. Therefore, this conductive network not only effectively improves the conductive environment of the lithium supplement, but the carbon material can also act as a catalyst, resulting in a significant decrease in the decomposition voltage of the lithium supplement.

[0166] Therefore, by controlling the mass ratio of lithium replenishing agent to positive electrode active material within the above range, the lithium replenishing agent can perform delithiation better than the positive electrode active material particles, releasing sufficient lithium ions to compensate for the loss of active lithium in the battery cell during the first charge, thereby effectively improving the electrochemical performance of the battery cell.

[0167] In some embodiments, the lithium replenishing agent may be a ternary lithium replenishing agent or a binary lithium replenishing agent.

[0168] For example, the chemical formula of a ternary lithium supplement is Li a M b O cWhere M is at least one element selected from Fe, Ni, Mn, Cu, Zn, Co, Cr, Zr, Sb, Ti, V, Mo, Sn, etc., and 1≤a≤8, 0<b, 0<c<7. In specific embodiments, the ternary lithium supplement can be Li5FeO4, Li6MnO4, Li6CoO4, Li6ZnO4, Li2NiO2, LiFeO2, Li2CuO2, Li2CoO2, Li2MnO2, Li2Ni 0.5 Mn 1.5 O4, Li2Ni d Cu (1-d) At least one of O2 (0 < d < 1), etc.

[0169] For example, the general chemical formula of a binary lithium supplement is Li. k M m Where M is at least one element selected from S, P, N, F, B, O, Se, and Te, and 1 ≤ k ≤ 5 and 0 ≤ m. Binary lithium supplementers include, but are not limited to, at least one of Li3N, Li2S, LiF, Li3P, Li2Se, and Li2O.

[0170] For example, lithium supplements can also be organic lithium salts with high decomposition voltages, such as Li2C2O4 (delithiation potential 4.7V), LiOH (delithiation potential 4.8V), Li4SiO4 (delithiation potential 4.5V), Li3PO4 (delithiation potential exceeding 4V), Li2CO3 (delithiation potential 4.7V), etc.

[0171] A third aspect of this application provides a battery device comprising a plurality of battery cells described in the above embodiments.

[0172] The battery device mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells, which are connected in series, parallel, or mixed connections via a busbar.

[0173] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells.

[0174] As an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells together to form an independent module. As another example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0175] In some embodiments, the battery device may be a battery pack, which includes a housing and one or more individual battery cell assemblies housed within the housing.

[0176] As an example, the battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.

[0177] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0178] As an example, the enclosure may include a first enclosure and a second enclosure. The first enclosure and the second enclosure are fastened together to form a closed space inside the enclosure to house the individual battery cells. Here, "closed" refers to covering or closing, and can be either sealed or unsealed. The first enclosure may be a top cover or a bottom plate.

[0179] As an example, the enclosure may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are connected to the frame, creating an enclosed space inside the enclosure to house the individual battery cells.

[0180] The following description, with appropriate reference to the accompanying drawings, describes the battery cells and battery devices provided in the embodiments of this application.

[0181] Figure 1 This is an exploded view of a battery device 100 as an example. The battery device 100 includes a housing 10 and battery cell assemblies 20, with the battery cell assemblies 20 housed within the housing 10. The housing 10 provides a space for housing the battery cell assemblies 20 and can have various structures. In some embodiments, the housing 10 may include a first housing 11 and a second housing 12, which overlap each other, collectively defining a closed space for housing the battery cell assemblies 20. Of course, the housing 10 formed by the first housing 11 and the second housing 12 can have various shapes, such as a cylinder, a cuboid, etc. Multiple battery cell assemblies 20 can be arranged in any manner within the battery housing.

[0182] In the battery device 100, there can be one or more battery cell components 20. Multiple battery cell components 20 can be connected in series, parallel, or in a mixed manner. A mixed connection means that multiple battery cell components 20 are connected in both series and parallel. Multiple battery cell components 20 can be directly connected in series, parallel, or in a mixed manner, and then the whole formed by multiple battery cell components 20 is housed in the housing 10. Of course, the battery device 100 can also be formed by first connecting multiple battery cell components 20 in series, parallel, or in a mixed manner to form a battery module, such as a battery module or battery pack. Multiple battery modules are then connected in series, parallel, or in a mixed manner to form a whole and housed in the housing 10.

[0183] Battery cell assembly 20 includes multiple battery cells 30. Figure 2This is an exploded view of a single battery cell 30 as an example. The single battery cell 30 includes a housing 31, a cover plate 33, an electrode assembly 32, and other functional components.

[0184] The housing 31 may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The housing 31 is a hollow structure with an opening at one end, and the housing 31 is used to cooperate with the cover plate 33 to form an internal environment for accommodating the electrode assembly 32, electrolyte, and other functional components. The housing 31 can be of various shapes and sizes, such as cuboid, cylindrical, hexagonal prism, etc. Specifically, the shape of the housing 31 can be determined according to the specific shape and size of the electrode assembly 32. The material of the housing 31 can be, but is not limited to, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and is not limited here. The cover plate 33 is a component that covers the opening of the housing 31 to isolate the internal environment of the battery cell 30 from the external environment. The material of the cover plate 33 can be, but is not limited to, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and is not limited here.

[0185] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0186] A fourth aspect of this application provides an energy storage device, including a plurality of battery cells or battery devices as described above, wherein the battery cells or battery devices are used to store or provide electrical energy.

[0187] The energy storage device mentioned in the embodiments of this application includes one or more battery clusters to improve the voltage and capacity of the energy storage device. A battery cluster may include multiple battery devices, which are connected in series via a busbar to increase the voltage of the energy storage device. When the energy storage device includes multiple battery clusters, the multiple battery clusters are connected in parallel to increase the capacity of the energy storage device.

[0188] Energy storage devices can be used in energy storage power stations, wind power generation systems, solar power generation systems, mobile power systems, or temporary power supply systems. Energy storage devices can store electrical energy as needed and output it when appropriate. For example, energy storage devices can store electrical energy during off-peak hours and provide power to relevant users or electrical equipment during peak hours.

[0189] In some embodiments, the energy storage device is an energy storage container or an energy storage cabinet.

[0190] In some embodiments, the energy storage device may include a cabinet and one or more battery clusters housed within the cabinet.

[0191] In some embodiments, the energy storage device may include modules such as a thermal management module, a main control module, a central control module, a power distribution module, and a fire protection module.

[0192] As an example, the thermal management module may include a liquid cooling unit that supplies coolant to each battery device via piping to regulate the temperature of the individual battery cells.

[0193] As an example, the main control module can serve as the battery management unit for the battery cluster, used to monitor and manage the battery cluster. The main control module can monitor information such as the current, voltage, power, or temperature of the battery cluster. For instance, it can control the charging and discharging current and voltage of the battery cluster. The main control module includes auxiliary battery management units, integrated switches, and other modules.

[0194] As an example, the central control module can serve as the battery management unit for an energy storage device, used to monitor and manage the device. The central control module can monitor information such as the energy storage device's current, voltage, power, state of charge, or temperature. For instance, it can control the charging and discharging current and voltage of the energy storage device. As an example, the central control module includes modules such as an insulation monitoring module, a main battery management unit, and Ethernet and fiber optic conversion modules.

[0195] As an example, the fire protection module includes a control panel, detectors, alarm devices, etc., used to detect, alarm, or extinguish fires in the energy storage system.

[0196] As an example, the power distribution module can be used to distribute power to the power modules of the energy storage device.

[0197] A fifth aspect of this application provides an energy storage system, including a power conversion device and an energy storage device as described in the above embodiments, wherein the power conversion device is used to electrically connect a power generation device and an energy storage device.

[0198] In some embodiments, the energy storage system may include one or more energy storage devices and a power conversion device, the power conversion device being connected between the power generation device and the energy storage device. The power generation device generates electrical energy, which can be stored in the energy storage device through the power conversion device. As examples, the power generation device may specifically be a solar panel, hydroelectric power generation equipment, thermal power generation equipment, wind power generation equipment, etc. The specific type of power generation device is not limited in this application.

[0199] The sixth aspect of this application provides an electrical device, including a battery cell, a battery device, an energy storage device, or an energy storage system as described in the above embodiments, wherein the battery cell or battery device is used to store or provide electrical energy.

[0200] The technical solutions described in the embodiments of this application are applicable to various electrical devices that use individual battery cells, such as mobile phones, portable devices, laptops, electric vehicles, electric toys, power tools, vehicles, ships, and spacecraft. For example, spacecraft include airplanes, rockets, space shuttles, and spacecraft.

[0201] A seventh aspect of this application provides a charging network, including a charging pile and an energy storage device or an energy storage system as described in the above embodiments, wherein the energy storage device is used to provide electrical energy to the charging pile.

[0202] In the above embodiments, the charging pile is electrically connected to an energy storage device, which provides power to the charging pile. The charging pile is also electrically connected to a battery within the energy storage device via a cable, allowing the battery to supply its stored energy to the charging pile. The charging pile has one or more connectors for connecting to electrical equipment (such as a vehicle), thereby enabling the charging equipment to receive power.

[0203] Energy storage devices can be located inside the charging pile (e.g., an integrated energy storage and charging unit) or outside the charging pile.

[0204] Example

[0205] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0206] Example 1

[0207] This embodiment provides a single battery cell.

[0208] [Preparation of the positive electrode sheet]

[0209] The positive electrode active material comprises positive electrode active material particles (lithium nickel manganese oxide) in a mass ratio of 90:10 and a coating material. The coating material forms a coating layer on the surface of the positive electrode active material particles in a discontinuous form. The coating material includes iron phosphate and carbon materials, with the carbon material coating the surface of the iron phosphate to form a shell. The Dv150 particle size of the positive electrode active material particles is 3 μm, the Dv250 particle size of the coating material is 100 nm, the coating layer thickness is 100 nm, and the mass percentage of carbon material in the coating material is 4 wt%.

[0210] The preparation method of the above-mentioned positive electrode active material includes the following steps:

[0211] S1. Ferric phosphate is subjected to high-energy ball milling to obtain D. v350 nano-sized iron phosphate particles with a diameter of around 100 nm.

[0212] S2: The carbon source and nano-sized iron phosphate are mixed by a mixer at 1000 rpm / 20 min, and then sintered at 750 °C for 8 h under an inert atmosphere, so that the carbon source forms carbon material that coats the surface of the metal phosphate, thus obtaining a core-shell structured coating material.

[0213] S3. The coating material and lithium nickel manganese oxide are mixed by a mixer at 1000 rpm / 20 min, and then sintered at 550 °C for 6 h under an inert atmosphere to obtain the positive electrode active material.

[0214] The above-mentioned positive electrode active material, conductive agent carbon black (Super P), and binder PVDF are dispersed in N-methylpyrrolidone (NMP) at a weight ratio of 95:5:5 and thoroughly stirred and mixed to form a uniform positive electrode slurry. The positive electrode slurry is coated on two opposing surfaces of the positive electrode current collector aluminum foil, and then dried, cold-pressed, and cut to obtain the positive electrode sheet.

[0215] [Preparation of the negative electrode sheet]

[0216] Artificial graphite, conductive carbon black, carboxymethyl cellulose (CMC) binder, and water solvent are uniformly mixed in a weight ratio of 95:2:3:100 to obtain a negative electrode slurry. The negative electrode slurry is uniformly coated on two opposing surfaces of the negative electrode current collector copper foil. After drying, cold pressing, and cutting, a negative electrode sheet is obtained.

[0217] [Preparation of Electrolyte]

[0218] In an argon-filled glove box (water content <10 ppm, oxygen content <1 ppm), ethylene carbonate, diethyl carbonate, and dimethyl carbonate were mixed in a volume ratio of 1:1:1. LiPF6 was then dissolved in this mixture to obtain the electrolyte. The concentration of LiPF6 in the electrolyte was 1 mol / L.

[0219] [Isolation membrane]

[0220] A polyethylene film with a thickness of 13μm was used as the separator.

[0221] [Preparation of battery cells]

[0222] The prepared positive electrode, negative electrode, and separator are arranged in the order of positive electrode-separator-negative electrode. The separator is positioned between the positive and negative electrodes to isolate them. They are then stacked to form a core. The resulting core is then placed in an aluminum-plastic film, electrolyte is injected, and the process involves vacuum sealing, aging, formation (0.1C charging to 4.6V), secondary sealing, and capacity sorting to complete the preparation of a single lithium-ion battery cell.

[0223] Examples 2-18

[0224] Examples 2-18 provide a single battery cell, wherein the main difference between the single battery cell and Example 1 is that the positive electrode sheet is different, specifically: the mass ratio of positive electrode active material particles to coating material, and the D of the positive electrode active material particles. v1 50 particle size, coating material D v2 At least one of the following must be different: particle size, mass percentage of carbon material in the coating material, and mass ratio of positive electrode active material to lithium supplementer. See Table 1 for details.

[0225] Table 1

[0226]

[0227]

[0228] In Table 1:

[0229] W1 represents the mass ratio of positive electrode active material particles to coating material, W2 represents the mass percentage of carbon material in the coating material, and W3 represents the mass ratio of positive electrode active material to lithium supplement.

[0230] D1 represents the Dv150 particle size of the positive electrode active material particles; D2 represents the Dv250 particle size of the coating material.

[0231] H represents the thickness of the coating layer formed by the coating material on the surface of the positive electrode active material particles.

[0232] A represents the metal phosphate component; B represents the lithium supplement component.

[0233] Comparative Example 1

[0234] This comparative example provides a single battery cell. The difference from Example 1 is that the positive electrode active material only includes lithium nickel manganese oxide, while all other aspects are the same, as detailed in Table 1.

[0235] Comparative Example 2

[0236] This comparative example provides a single battery cell. The difference from Example 1 is that the positive electrode active material only includes lithium nickel manganese oxide, and the positive electrode film also contains a lithium replenishing agent. Everything else is the same, as detailed in Table 1.

[0237] Performance testing

[0238] (1) Mn dissolution test

[0239] The meaning of manganese content is well-known in the art and can be tested using methods known in the art. The content of the target element can be determined according to EPA 6010D-2014, "Inductively Coupled Plasma Atomic Emission Spectrometry," using a Thermo Fisher Scientific ICAP-7000 inductively coupled plasma atomic emission spectrometer (ICP-OES).

[0240] The specific testing method is as follows:

[0241] The material on the surface of the negative electrode sheet is peeled off and used as the sample to be tested.

[0242] 0.1 g of the sample to be tested was digested by microwave with 3 mL of concentrated nitric acid and 9 mL of concentrated hydrochloric acid. After digestion, the sample was added to a 50 mL volumetric flask and diluted to volume. The content of the target element was then determined by ICAP-7000 ICP-OES.

[0243] (2) Electrochemical performance testing

[0244] The battery capacity retention rate test process is as follows:

[0245] At 25°C, a single battery cell is charged and discharged at 1C / 1C, and the resulting capacity is recorded as the initial capacity C0. The above steps are repeated for the same battery, and the discharge capacity Cn of the battery after the nth cycle is recorded. The battery capacity retention rate after each cycle is Pn = Cn / C0 * 100%, thus obtaining the battery capacity retention rate.

[0246] During this test, the first loop corresponds to n=1, the second loop corresponds to n=2, ... the 1000th loop corresponds to n=1000.

[0247] The test procedure for DC impedance is as follows:

[0248] After the battery has undergone 1000 cycles, it was charged and discharged at 0.1C / 0.1C for one week at 25°C, then recharged to 50% SOC, and discharged for 10 seconds at 3C on a charging and discharging device to obtain the corresponding DCR value.

[0249] The testing process for the initial charge capacity and initial discharge capacity is as follows:

[0250] The individual battery cells are charged and discharged at 0.33C / 0.33C.

[0251] The performance test results of the battery cells provided in Examples 1-18 and Comparative Examples 1-2 are listed in Table 2 below.

[0252] Table 2

[0253]

[0254]

[0255] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized in that, The device includes a positive electrode sheet, which includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector. The positive electrode film layer includes a positive electrode active material, which includes positive electrode active material particles and a coating material. The coating material is discontinuously coated on the surface of the positive electrode active material particles to form a coating layer. The coating material includes metal phosphates and carbon materials.

2. The battery cell as described in claim 1, characterized in that, The coating material has a core-shell structure, wherein the core material of the core-shell structure is the metal phosphate, and the outer shell material of the core-shell structure is the carbon material.

3. The battery cell as described in any one of claims 1 or 2, characterized in that, The coating material satisfies at least one of the following characteristics (1) to (4): (1) The Dv250 particle size of the coating material is <300nm; (2) The thickness of the shell is 1nm-5nm; (3) The carbon material accounts for 1wt%-8wt% of the mass of the coating material; (4) The metal in the metal phosphate includes at least one of iron, nickel, cobalt and manganese.

4. The battery cell according to any one of claims 1 to 3, characterized in that, The coating material forms a coating layer by coating at least a portion of the surface of the positive electrode active material particles in an island-like manner.

5. The battery cell according to any one of claims 1 to 4, characterized in that, The thickness of the coating layer is <300nm.

6. The battery cell according to any one of claims 1 to 5, characterized in that, The thickness of the coating layer is 20nm-100nm.

7. The battery cell according to any one of claims 1 to 6, characterized in that, The mass ratio of the positive electrode active material particles to the coating material is 95-80:5-20.

8. The battery cell according to any one of claims 1 to 7, characterized in that, The positive electrode active material particles D v1 The particle size of 50 particles ranges from 3μm to 15μm.

9. The battery cell according to any one of claims 1 to 8, characterized in that, The positive electrode film layer also includes a lithium replenishing agent, the decomposition voltage of which is lower than the standard decomposition voltage of the lithium replenishing agent.

10. The battery cell as described in claim 9, characterized in that, The mass ratio of the lithium supplement to the positive electrode active material is 0-10:99-90.

11. A method for preparing a single battery cell, characterized in that, Includes the following steps: Metal phosphates are mixed with a carbon source and then sintered to obtain a coating material. The coating material is discontinuously coated onto the surface of positive electrode active material particles to obtain a positive electrode active material. A positive electrode slurry containing the positive electrode active material is prepared, and the positive electrode slurry is coated on at least one surface of the positive electrode current collector to form a positive electrode film layer, thereby obtaining a positive electrode sheet; The positive and negative electrode sheets are assembled to obtain a single battery cell.

12. The method for preparing a single battery cell as described in claim 11, characterized in that, The sintering process includes: sintering at 700℃-800℃ for 5-10 hours; and / or The step of discontinuously coating the surface of the positive electrode active material particles with the coating material includes: mixing the coating material with the positive electrode active material particles and sintering at 500℃-600℃ for 4h-8h.

13. The method for preparing a battery cell as described in claim 11 or 12, characterized in that, The prepared positive electrode slurry also contains a lithium supplement agent, and the mass ratio of the lithium supplement agent to the positive electrode active material is 1-10:99-90.

14. A battery device, characterized in that, It includes multiple battery cells as described in any one of claims 1-10.

15. An energy storage device, characterized in that, It includes a plurality of battery cells as described in any one of claims 1-10 or a plurality of battery devices as described in claim 14.

16. An energy storage system, characterized in that, It includes a power conversion device and an energy storage device as described in claim 15, wherein the power conversion device is used to electrically connect the power generation device and the energy storage device.

17. An electrical device, characterized in that, Includes a battery cell as described in any one of claims 1-10, a battery device as described in claim 14, an energy storage device as described in claim 15, or an energy storage system as described in claim 16, wherein the battery cell or the battery device is used to store or provide electrical energy.

18. A charging network, characterized in that, It includes a charging pile and an energy storage device as described in claim 15 or an energy storage system as described in claim 16, wherein the energy storage device is used to provide electrical energy to the charging pile.

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