Negative electrode sheet, battery, energy storage device, and electric device

Abstract

The application provides a negative electrode sheet, a battery, an energy storage device and an electric equipment. The negative electrode sheet comprises a negative electrode current collector, at least one side of the negative electrode current collector is provided with a negative electrode active material layer, the negative electrode active material layer comprises a negative electrode active material, a plurality of tabs are arranged along the length direction of the negative electrode sheet, and the negative electrode sheet satisfies a relationship formula: d1 / d2=x / y, wherein d1 represents the interval of adjacent tabs, and the unit is cm; d2 represents the width of the negative electrode sheet, and the unit is cm; x represents the OI value of the negative electrode active material; and y represents the porosity of the negative electrode active material layer.

Description

Technical Field

[0001] This application relates to the field of energy storage technology, and in particular to a negative electrode sheet, a battery, an energy storage device, and an electrical device. Background Technology

[0002] Secondary batteries (such as lithium-ion batteries) have advantages such as high energy density, low self-discharge, and light weight, and are therefore widely used in energy storage devices and other fields.

[0003] As one of the main structures of a secondary battery, the negative electrode plays a crucial role in its performance. However, during battery cycling, factors such as insufficient kinetics of the negative electrode active material, poor electrolyte wetting, or stress concentration can easily lead to lithium plating on the negative electrode, especially at low temperatures, thus affecting the cycle performance of the secondary battery. Summary of the Invention

[0004] To address the aforementioned technical problems, this application discloses a negative electrode sheet, a battery, an energy storage device, and an electrical appliance to improve the lithium deposition problem of the negative electrode sheet, especially the lithium deposition problem of the negative electrode sheet under low temperature conditions, and improve the cycle performance of the secondary battery.

[0005] In a first aspect, this application provides a negative electrode sheet, the negative electrode sheet comprising a negative electrode current collector, at least one side of the negative electrode current collector having a negative electrode active material layer, the negative electrode active material layer comprising a negative electrode active material, and having a plurality of tabs disposed along the length direction of the negative electrode sheet, the negative electrode sheet satisfying the following relationship:

[0006] Wherein, d1 represents the distance between adjacent tabs, in cm;

[0007] d2 represents the width of the negative electrode plate, in cm;

[0008] x represents the OI value of the negative electrode active material;

[0009] y represents the porosity of the negative electrode active material layer.

[0010] In some embodiments of this application, the negative electrode sheet satisfies the following relationship:

[0011] In some embodiments of this application, x ≤ 15.

[0012] In some embodiments of this application, 0.2 ≤ y ≤ 0.35.

[0013] In some embodiments of this application, 0.1 ≤ d1 ≤ 0.7.

[0014] In some embodiments of this application, 10 ≤ d2 ≤ 24.

[0015] In some embodiments of this application, the areal density of the negative electrode active material layer is CW, 0.11 g / 1540.25 mm. 2 ≤CW≤0.14g / 1540.25mm 2 .

[0016] In some embodiments of this application, the median particle size of the negative electrode active material is Dv50, where 5μm≤Dv50≤12μm.

[0017] Secondly, this application provides a battery including the negative electrode sheet described in the first aspect.

[0018] In some embodiments of this application, the battery has a wound structure, the central region of which has a cavity with an inner diameter of L, where 5mm ≤ L ≤ 8mm.

[0019] Thirdly, this application provides an energy storage device, including a housing and at least one battery as described in the second aspect, the battery being housed within the housing.

[0020] Fourthly, this application provides an electrical device including the energy storage device described in the third aspect, wherein the energy storage device supplies power to the electrical device.

[0021] Compared with the prior art, this application has at least the following beneficial effects:

[0022] This application provides a negative electrode sheet, a battery, an energy storage device, and an electrical device, wherein the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer, the negative electrode active material layer includes a negative electrode active material, and multiple tabs are arranged along the length direction of the negative electrode sheet. The negative electrode sheet satisfies the following relationship: Improve the lithium plating problem on the negative electrode, especially the lithium plating problem on the negative electrode under low temperature conditions, and improve the cycle performance of the secondary battery, especially the low temperature cycle performance. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the negative electrode sheet of one embodiment of this application (viewed along the thickness direction);

[0025] Figure 2This is a schematic diagram of the negative electrode sheet of one embodiment of this application (viewed along the width direction);

[0026] Figure 3 This is a schematic diagram of the structure of a lithium-ion battery according to one embodiment of this application;

[0027] Figure 4 This is a schematic diagram of the structure of an energy storage system according to one embodiment of this application;

[0028] Figure 5 This is a schematic diagram of the energy storage system according to another embodiment of this application;

[0029] Figure 6 This is a schematic diagram of the energy storage system according to another embodiment of this application.

[0030] Explanation of reference numerals in the attached figures:

[0031] 10-Negative electrode sheet, 11-Negative current collector, 12-Negative active material layer, 13-Electrical tab, 14-Cavity, 15-Shell, 400-Energy storage system, 410-First power conversion device, 420-First user load, 430-Second user load, 440-Energy storage device, 450-High voltage cable, 460-Second power conversion device, 470-Automobile, 480-Photovoltaic-energy storage-charging station. Detailed Implementation

[0032] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0033] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0034] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in certain circumstances to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0035] Furthermore, the terms "installation," "setup," "equipped with," "connection," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; 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, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0036] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, components, or parts (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, components, or parts. Unless otherwise stated, "a plurality of" means two or more.

[0037] It should be noted that this application uses lithium-ion batteries as an example of secondary batteries to explain the application, but the secondary batteries in this application are not limited to lithium-ion batteries.

[0038] During lithium-ion battery cycling, bright streaks tend to appear first in the central region of the negative electrode sheet due to factors such as insufficient kinetics of the negative electrode active material, poor electrolyte wetting, or stress concentration. These bright streaks are formed by changes in the microscopic interface of the negative electrode active material. Subsequently, the bright streaks gradually expand and form lithium plating bands on the surface of the negative electrode sheet, affecting the cycle performance of the lithium-ion battery. These bright streaks are especially prone to appear under low-temperature conditions (e.g., below -20°C).

[0039] In view of this, this application provides a negative electrode plate, with reference to Figure 1 and Figure 2 The negative electrode 10 includes a negative current collector 11, at least one side of which has a negative active material layer 12. The negative active material layer 12 includes a negative active material. A plurality of tabs 13 are disposed along the length of the negative electrode 10. The negative electrode 10 satisfies the following relationship: In another alternative implementation, For example, The values ​​are 1.6, 1.8, 2, 2.3, 2.5, 3, 5, 6, 7, or 7.4. Where d1 represents the distance between adjacent tabs in cm; d2 represents the width of the negative electrode sheet in cm; x represents the orientation degree of the negative electrode active material, i.e., the OI value; and y represents the porosity of the negative electrode active material layer.

[0040] The inventors discovered that, from the perspective of the negative electrode sheet, the greater the porosity of the negative electrode active material layer, the more developed the pore structure of the negative electrode sheet, the better the wettability of the electrolyte, and the faster the liquid phase transport speed of active lithium ions. During high-rate charging, active lithium ions are more easily reduced, thereby reducing the formation of lithium dendrites on the surface of the negative electrode sheet. Therefore, the greater the porosity of the negative electrode active material layer, the better the kinetic performance of the lithium-ion battery, and it can maintain good electrochemical performance under operating conditions such as low temperature and high-rate charging. However, when the porosity of the negative electrode active material layer is too large, the mass of active material per unit area is reduced accordingly, and the energy density of the lithium-ion battery also decreases. The microstructure of the negative electrode active material (such as graphite) has an impact on electrochemical performance, and the OI value indicates the packing orientation of the negative electrode active material particles on the negative electrode current collector. A smaller OI value results in a shorter lithium-ion transport path and lower diffusion resistance during lithium-ion insertion and extraction, which is beneficial for improving rate performance. It also allows for more stress release directions during charging and discharging, reducing the risk of lithium-ion battery swelling. However, this also increases the processing cost of the negative electrode active material. Conversely, a larger OI value results in a longer lithium-ion transport path, higher diffusion resistance, fewer stress release directions during charging and discharging, and a greater risk of lithium-ion battery swelling. Based on this analysis, a negative electrode with suitable porosity and OI value can balance low-temperature performance, fast-charging performance, and high energy density.

[0041] Furthermore, the design of the negative electrode is also a key factor affecting the electrical performance of lithium-ion batteries. Especially for negative electrodes with multi-tab structures, the current density distribution on the negative electrode is not uniform; the current density decreases along the direction away from the tabs, meaning the current density is highest near the tabs and lowest further away. Moreover, the current density is also related to lithium-ion insertion / extraction; a higher current density is more conducive to lithium-ion insertion / extraction, thus facilitating rapid charging and discharging of the lithium-ion battery. Further research by the inventors revealed that the smaller d1×d2 is, the greater the current density within the same reaction time, the faster the electrolyte wetting rate, the higher the reaction utilization rate of the negative electrode active material, and the more uniform the reaction inside the electrode. However, d1 cannot be too small, otherwise the tabs will squeeze each other after winding, affecting the current conduction performance of the tabs, and the electrolyte wetting is also affected. Furthermore, d2 cannot be too small, otherwise the negative electrode sheet becomes too narrow, making it difficult to meet the requirements for battery energy density. When d1×d2 is larger, the current density of the negative electrode sheet decreases along the first direction, resulting in a lower utilization rate of the negative electrode active material far from the tab. Under conditions such as low temperature and high-rate charging, some negative electrode active materials may not be able to participate in the reaction, i.e., "particle stagnation" occurs. A large state of charge (SOC) gradient is easily formed inside the lithium-ion battery, which can easily lead to severe concentration polarization inside the negative electrode sheet and thus cause capacity decay. Further research by the inventors revealed that, compared to the single-tab structure of the negative electrode, the maximum current transmission path of the multi-tab structure of the negative electrode is the width direction of the negative electrode, i.e., the first direction. Therefore, the impact of d2 on the performance of lithium-ion batteries also needs to be considered.

[0042] Based on the above research, when d1, d2, x, and y satisfy the above relationship, the lithium plating problem of the negative electrode sheet under low temperature conditions is improved, and the lithium-ion battery has better cycle performance, especially low temperature cycle performance.

[0043] In some embodiments of this application, x ≤ 15; in another alternative embodiment, 6 ≤ x ≤ 15. For example, x is 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15. This is beneficial for balancing the rate performance, expansion risk, and processing costs of lithium-ion batteries.

[0044] In some embodiments of this application, 0.2 ≤ y ≤ 0.35. For example, y is 0.2, 0.23, 0.25, 0.3, 0.33, or 0.35. This is beneficial for balancing the electrolyte wettability of the negative electrode and the energy density of the lithium-ion battery.

[0045] In some embodiments of this application, 0.1 ≤ d1 ≤ 0.7. For example, d1 is 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, or 0.7. This is beneficial for balancing the wettability of the electrolyte and the current conduction performance of the tabs.

[0046] In some embodiments of this application, 10 ≤ d2 ≤ 24. For example, d2 is 10, 13, 15, 18, 20, 22, or 24. d2 within the above range is beneficial for balancing electrolyte wetting and lithium-ion battery energy density, thereby enabling the negative electrode to have good wettability while simultaneously achieving high energy density in the lithium-ion battery.

[0047] In some embodiments of this application, the areal density of the negative electrode active material layer is CW, 0.11 g / 1540.25 mm. 2 ≤CW≤0.14g / 1540.25mm 2 For example, CW is 0.11g / 1540.25mm. 2 0.12g / 1540.25mm 2 0.13g / 1540.25mm 2 Or 0.14g / 1540.25mm 2 This allows lithium-ion batteries to achieve both high-rate, long-cycle performance and high energy density.

[0048] In some embodiments of this application, the median particle size of the negative electrode active material is Dv50, where 5 μm ≤ Dv50 ≤ 12 μm. For example, Dv50 is 5 μm, 7 μm, 9 μm, 10 μm, 11 μm, or 12 μm. This is advantageous for obtaining a negative electrode with a low OI value and a high ion diffusion rate.

[0049] In this application, Dv50 represents the particle size that, in the volumetric particle size distribution, reaches 50% of the total volumetric size, starting from the smallest particle size.

[0050] This application does not impose any particular restrictions on the raw materials and coating agents used to prepare the negative electrode active material, as long as they can achieve the purpose of this application. For example, the raw materials include at least one of petroleum coke, pitch coke, needle coke, green coke, semi-calcined coke, and calcined coke; the coating agents include at least one of pitch, petroleum residue oil, indene resin, epoxy resin, furfural resin, and bio-based resin.

[0051] This application does not impose any particular restrictions on the method of controlling the OI value of the negative electrode active material, as long as the purpose of this application can be achieved. For example, the OI value of the negative electrode active material can be controlled by adjusting the type of raw materials used to prepare the negative electrode active material, the particle size of the negative electrode active material, or by modifying the negative electrode active material.

[0052] This application does not impose any particular limitation on the method of controlling the porosity of the negative electrode active material layer, as long as the purpose of this application can be achieved. For example, the porosity of the negative electrode active material layer can be controlled during the preparation of the negative electrode sheet by adjusting the rolling pressure, rolling method, spraying a pore-forming agent onto the negative electrode active material layer, etc.

[0053] This application also provides a battery including the negative electrode sheet described in any embodiment of this application.

[0054] The lithium-ion battery of this application also includes a positive electrode, a separator, and an electrolyte, wherein the separator is located between the positive electrode and the negative electrode and plays a role in isolation.

[0055] In some embodiments of this application, reference is made to Figure 3 The lithium-ion battery has a wound structure with a cavity 14 in the central region. The cavity 14 can be cylindrical, with an inner diameter L of 5mm ≤ L ≤ 8mm. For example, L can be 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, or 8mm. This cavity 14 allows for the storage of a portion of the electrolyte, improving electrolyte wetting and preventing excessive stress at the center of the negative electrode due to an excessively large cavity diameter. This avoids the problem of bright spots appearing at the center of the negative electrode due to poor electrolyte wetting and high internal stress. It should be noted that... Figure 3 For illustrative purposes only, only part of the tab 13 is shown. Additionally, the lithium-ion battery also has a casing 15, and the lithium-ion battery can be a cylindrical lithium-ion battery.

[0056] In this application, the negative electrode material layer can be disposed on one or both surfaces of the negative electrode current collector along its thickness direction. Specifically, the negative electrode material layer can be disposed on a portion or the entire surface of the negative electrode current collector. This application does not impose any particular limitation on the negative electrode current collector, as long as it achieves the purpose of this application; for example, it can include, but is not limited to, copper foil, copper alloy foil, nickel foil, or composite current collectors. Similarly, this application does not impose any particular limitation on the thickness of the negative electrode current collector, as long as it achieves the purpose of this application; for example, a thickness of 4 μm to 12 μm is acceptable. The single-sided thickness of the negative electrode material layer in this application can be 70 μm to 200 μm.

[0057] In this application, the negative electrode material layer may also include a negative electrode binder. This application does not impose any particular limitation on the negative electrode binder, as long as it can achieve the purpose of this application. For example, it may include, but is not limited to, at least one of acrylate, polyamide, polyimide, polyamide-imide, polyvinylidene fluoride (PVDF), styrene-butadiene rubber (SBR), sodium alginate, polyvinyl alcohol, polytetrafluoroethylene, polyacrylonitrile, sodium carboxymethyl cellulose (CMC), and potassium carboxymethyl cellulose.

[0058] This application does not impose any particular limitation on the positive electrode sheet, as long as it achieves the purpose of this application. For example, the positive electrode sheet typically includes a positive current collector and a positive electrode material layer. The positive electrode material layer can be disposed on one surface or on two surfaces in the thickness direction of the positive current collector. In this application, the positive electrode material layer is disposed on the surface of the positive current collector, that is, the positive electrode material layer can be disposed on a portion of a surface of the positive current collector or on the entire surface of a surface of the positive current collector. This application does not impose any particular limitation on the positive current collector, as long as it achieves the purpose of this application, it can be, for example, including but not limited to aluminum foil, aluminum alloy foil, or composite current collectors. In this application, there is no particular limitation on the thickness of the positive current collector, as long as it achieves the purpose of this application, for example, a thickness of 8μm to 13μm. The single-sided thickness of the positive electrode material layer in this application can be 100μm to 200μm.

[0059] In this application, the positive electrode material layer includes a positive electrode material. This application does not have any particular restrictions on the positive electrode material, as long as it can achieve the purpose of this application. For example, it may include at least one of lithium iron phosphate, lithium-rich manganese-based materials, lithium cobalt oxide, lithium manganese oxide, and lithium manganese iron phosphate.

[0060] In this application, the positive electrode material layer may further include a positive electrode conductive agent. This application does not impose any particular limitation on the positive electrode conductive agent, as long as it can achieve the purpose of this application. For example, it may include, but is not limited to, at least one of conductive carbon black (Super P), carbon nanotubes (CNTs), carbon fibers, acetylene black, and graphene. The aforementioned carbon nanotubes may include, but are not limited to, single-walled carbon nanotubes and / or multi-walled carbon nanotubes. In this application, the positive electrode material layer may further include a positive electrode binder. This application does not impose any particular limitation on the positive electrode binder, as long as it can achieve the purpose of this application. For example, it may include, but is not limited to, at least one of PVDF, fluorinated resin, polypropylene resin, fiber-type binder, rubber-type binder, or polyimide-type binder.

[0061] The lithium-ion battery of this application also includes a separator. This application does not impose any particular limitation on the separator; those skilled in the art can choose according to actual needs, as long as the purpose of this application is achieved. For example, the separator may include a substrate layer and a surface treatment layer. The substrate layer is a nonwoven fabric, membrane, or composite membrane with a porous structure, and the material of the substrate layer is selected from at least one of polyethylene, polypropylene, polyethylene terephthalate, and polyimide. Specifically, a polypropylene porous membrane, a polyethylene porous membrane, a polypropylene nonwoven fabric, a polyethylene nonwoven fabric, or a polypropylene-polyethylene-polypropylene porous composite membrane can be selected.

[0062] The battery of this application also includes an electrolyte. This application does not impose any particular limitation on the electrolyte; those skilled in the art can choose according to actual needs, as long as it achieves the purpose of this application. For example, at least one of ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), ethyl propionate (EP), propyl propionate (PP), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), vinylene carbonate (VC), or fluoroethylene carbonate (FEC) can be mixed in a certain mass or volume ratio to obtain a non-aqueous organic solvent, and then lithium salt can be added to dissolve and mix evenly. This application does not limit the type of lithium salt, as long as it achieves the purpose of this application. For example, the lithium salt may include at least one of LiPF6, LiBF4, LiAsF6, LiClO4, LiB(C6H5)4, LiCH3SO3, LiCF3SO3, LiN(SO2CF3)2, LiC(SO2CF3)3, LiSiF6, lithium dioxolaneborate (LiBOB), or lithium difluoroborate.

[0063] This application does not impose any particular limitation on the concentration of lithium salt in the electrolyte, as long as it achieves the purpose of this application. Taking LiPF6 as an example, the concentration of LiPF6 in the electrolyte is 1 mol / L to 2 mol / L, for example, the concentration of LiPF6 is 1 mol / L, 1.3 mol / L, 1.5 mol / L, 1.8 mol / L or 2 mol / L.

[0064] The battery of this application also includes a casing. This application does not impose any particular restrictions on the casing, and those skilled in the art can choose one according to actual needs, as long as it can achieve the purpose of this application. For example, the casing may include an aluminum-plastic film.

[0065] This application does not impose any particular limitation on the preparation method of lithium-ion batteries. Any preparation method known in the art can be selected, as long as it can achieve the purpose of this application. For example, the preparation method of lithium-ion batteries includes, but is not limited to, the following steps: stacking positive electrode sheets, separators, and negative electrode sheets in sequence, and performing winding, folding, and other operations as needed to obtain a bare cell with a winding structure; adjusting parameters such as winding tension, winding needle diameter, and number of winding turns to adjust the inner diameter of the cavity in the central region of the winding structure; then placing the bare cell in a packaging bag, injecting electrolyte into the packaging bag, and sealing it to obtain a battery with a winding structure.

[0066] This application also provides an energy storage device, including a housing and at least one battery as described in any of the above embodiments, the battery being housed within the housing. The energy storage device with this battery exhibits excellent performance, which is beneficial for its use. Housing the battery within the housing increases its stability and protection, thereby extending the lifespan of the energy storage device. It is understood that the energy storage device may contain one or more batteries, and when the energy storage device contains multiple batteries, the multiple batteries can be connected in at least one manner, such as parallel or series connection.

[0067] This application also provides an electrical device including the energy storage device described in the above embodiments, which is beneficial for improving the product competitiveness and performance of the electrical device. In an optional embodiment, the electrical device includes an electrical device body, and the energy storage device is used to supply power to the electrical device body. In an optional embodiment, the electrical device body includes a positive terminal and a negative terminal, the positive electrode of the battery in the energy storage device is used to electrically connect to the positive terminal of the electrical device body, and the negative electrode of the battery in the energy storage device is used to electrically connect to the negative terminal of the electrical device body, so as to supply power to the electrical device.

[0068] The electrical equipment in this application may include, but is not limited to: containers, electric vehicles, electric cars, ships, spacecraft, electric toys, and power tools, etc. Among them, spacecraft include, for example, airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include, for example, stationary or mobile electric toys, specifically, electric car toys, electric ship toys, and electric airplane toys, etc. Power tools include, for example, metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, specifically, electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers.

[0069] Because the energy we need is highly time- and space-dependent, in order to utilize energy rationally and improve energy efficiency, it is necessary to store one form of energy in the same way or by converting it into another, and then release it in a specific energy form for future applications. Currently, the main way to generate green electricity is to develop green energy sources such as photovoltaics and wind power to replace fossil fuels.

[0070] Currently, the generation of green electricity generally relies on solar, wind, and hydropower. However, wind and solar power are generally characterized by strong intermittency and large fluctuations, which can cause grid instability, insufficient power during peak demand periods, and excessive power during off-peak periods. Unstable voltage can also damage the power grid. Therefore, insufficient electricity demand or insufficient grid capacity may lead to the problem of "wind and solar curtailment." Solving these problems requires energy storage. This involves converting electrical energy into other forms of energy through physical or chemical means and storing it. When needed, this energy can be converted back into electrical energy and released. Simply put, energy storage is like a large "power bank," storing electrical energy when solar and wind power are abundant and releasing the stored electricity when needed.

[0071] Taking electrochemical energy storage as an example, this solution provides an energy storage device 440, which is applied to an energy storage system 400. The energy storage device 440 is equipped with a set of chemical batteries, which mainly use the chemical elements in the batteries as energy storage medium. The charging and discharging process is accompanied by the chemical reaction or change of the energy storage medium. Simply put, the electrical energy generated by wind and solar energy is stored in the chemical batteries. When the use of external electrical energy reaches its peak, the stored electrical energy is released for use, or transferred to places with a shortage of electricity for use.

[0072] Current energy storage applications are quite widespread, including generation-side energy storage, grid-side energy storage, and consumption-side energy storage. The corresponding types of energy storage devices 440 include:

[0073] (1) Large-scale energy storage power stations (composed of multiple prefabricated energy storage modules) applied to wind power and photovoltaic power stations can help renewable energy power generation meet grid connection requirements and improve the utilization rate of renewable energy. As a high-quality active / reactive power source in the power supply side, the energy storage power station realizes the load matching of power in time and space, enhances the renewable energy absorption capacity, reduces instantaneous power changes, reduces the impact on the power grid, improves the problem of new energy power generation absorption, and is of great significance in power grid system backup, alleviating peak load power supply pressure and peak regulation and frequency regulation.

[0074] (2) The energy storage prefabricated cabin applied on the grid side mainly functions as peak regulation, frequency regulation and grid congestion relief. In terms of peak regulation, it can realize peak shaving and valley filling of electricity load, that is, charging the energy storage battery when the electricity load is low and releasing the stored electricity during the peak electricity load period, thereby achieving a balance between power production and consumption.

[0075] (3) Small energy storage cabinets applied to the electricity consumption side mainly function as self-consumption of electricity, peak-valley price arbitrage, capacity cost management, and improvement of power supply reliability. Depending on the application scenario, electricity consumption side energy storage can be divided into industrial and commercial energy storage cabinets, household energy storage devices, energy storage charging piles, etc., which are generally used in conjunction with distributed photovoltaics. Industrial and commercial users can use energy storage for peak-valley price arbitrage and capacity cost management. In the electricity market implementing peak-valley pricing, by charging the energy storage system when the electricity price is low and discharging the energy storage system when the electricity price is high, peak-valley price arbitrage can be achieved, reducing electricity costs. In addition, industrial enterprises subject to two-part tariffs can use energy storage systems to store energy during off-peak hours and discharge during peak loads, thereby reducing peak power and the maximum demand declared, achieving the goal of reducing capacity charges. Household photovoltaics with energy storage can improve the level of self-consumption of electricity. Due to high electricity prices and poor power supply stability, the demand for household photovoltaic installations is driven. Given that photovoltaic power generation occurs during the day, while user load is generally higher at night, configuring energy storage can better utilize photovoltaic power, improve self-consumption levels, and reduce electricity costs. Furthermore, energy storage is needed in areas such as communication base stations and data centers for backup power.

[0076] In some embodiments, see Figure 4 , Figure 4 This is a schematic diagram of the structure of an energy storage system 400 according to an embodiment of this application. Figure 1 This application Figure 4 The embodiments are illustrated using a home energy storage scenario in user-side energy storage as an example. The energy storage device 440 of this application is not limited to the home energy storage scenario.

[0077] This application provides an energy storage system 400, which includes a first power conversion device 410 (photovoltaic panel), a first user load 420 (household lighting fixture), a second user load 430 (e.g., household appliances such as air conditioners), and an energy storage device 440. The energy storage device 440 is a small energy storage box that can be wall-mounted on an outdoor wall. However, the energy storage device 440 is not limited to wall mounting and can also be placed in a user's residence in other ways. Specifically, the photovoltaic panel can convert solar energy into electrical energy during periods of low electricity prices, and the energy storage device 440 stores this electrical energy and supplies it to lighting fixtures and household appliances during peak electricity prices, or provides power during power outages / power interruptions.

[0078] In some embodiments, see Figure 5 , Figure 5 This is a schematic diagram of the structure of an energy storage system 400 according to an embodiment of this application. Figure 2 And this application Figure 5 The embodiments are illustrated using a shared energy storage scenario on the generation / distribution side as an example. The energy storage device 440 of this application is not limited to the energy storage scenario on the generation / distribution side.

[0079] This application provides an energy storage system 400, which includes: a high-voltage cable 450, a first power conversion device 410, a second power conversion device 460, and an energy storage device 440 provided in this application. In some embodiments of the power generation scenario, the second power conversion device 460 can be a wind power conversion device. Since the electricity generated by wind power conversion is volatile, random, and intermittent, the unstable electricity output by the wind power conversion device can be stored in the energy storage device 440 through grid connection. The energy storage device 440 is connected to the high-voltage cable and outputs smooth electricity to the power consumption side of the distribution network, realizing peak shaving and frequency regulation, and stable grid operation; or, wind power... The conversion device is always connected to the high-voltage cable. Under normal power generation conditions, the power output of the wind power conversion device is supplied to the power consumption side of the distribution network through the high-voltage cable. When the current power load is low and the wind power conversion device generates excess power, the excess power is first stored in the energy storage device 440 to reduce wind and solar curtailment rates and improve the problem of new energy power generation consumption. When the power load is high, the power grid issues an instruction to transmit the power stored in the energy storage device 440 together with the high-voltage cable 450 in grid-connected mode to supply power to the power consumption side. This provides the power grid with various services such as peak shaving, frequency regulation, and backup, giving full play to the peak shaving role of the power grid, promoting peak shaving and valley filling, and alleviating the power supply pressure of the power grid.

[0080] In some embodiments on the distribution network side, the first power conversion device 410 can be a photovoltaic panel, and the energy storage device 440 is connected to the high-voltage cable 450 and installed downstream of the high-voltage cable 450 and between the user load. The electrical energy output by the photovoltaic power conversion device is stored in the energy storage device 440, which can respond in a timely manner to act as a backup power source when the power grid / distribution network fails; or, it can provide power supply support to alleviate line congestion when the high-voltage cable 450 transmission line is blocked, and to delay the economic pressure caused by the expansion of the power grid / distribution capacity when the power grid is planned to be expanded.

[0081] In some embodiments, see Figure 6 , Figure 6 This is a schematic diagram of the structure of an energy storage system 400 according to an embodiment of this application. Figure 3 And this application Figure 6 The embodiments are illustrated using an industrial and commercial energy storage scenario as an example. The energy storage device 440 of this application is not limited to industrial and commercial energy storage scenarios.

[0082] This application provides an energy storage system 400, which includes: an energy storage device 440, a high-voltage cable 450, a factory equipped with a first power conversion device 410, a photovoltaic-energy storage-charging station 480, and a vehicle 470. In some embodiments of industrial and commercial scenarios, the first power conversion device 410 can be a photovoltaic panel, which converts solar energy into electrical energy and stores it in the energy storage device 440 in the factory. In the event of a power grid failure, the energy storage device 440 provides power to ensure the safe and stable operation of the factory without interruption. Alternatively, when the factory's power load is high, the power grid issues an instruction to transmit the electricity stored in the energy storage device 440 in conjunction with the high-voltage cable 450 in a grid-connected mode to supply the factory with electricity, providing various services such as peak shaving / frequency regulation and backup for the power grid operation. In addition, the first power conversion device 410 can also convert solar energy into electrical energy and store it in the energy storage device 440 of the photovoltaic-energy storage-charging station 480, which can then directly charge the vehicle 470, making it fast and convenient.

[0083] Optionally, the first power conversion device 410 may include, but is not limited to, a photovoltaic panel, and the second power conversion device 460 may include, but is not limited to, a wind power conversion device. The first power conversion device 410 and the second power conversion device 460 can convert at least one of solar energy, light energy, wind energy, thermal energy, tidal energy, biomass energy, and mechanical energy into electrical energy.

[0084] Optionally, the energy storage device 440 may include, but is not limited to, energy storage applications such as energy storage power stations, hydropower / thermal / wind power generation systems, solar power generation systems, mobile power systems, smart home systems, or temporary power supply systems, and may also be applied in multiple fields such as data centers, military equipment, aerospace, charging piles, and electric vehicles.

[0085] Optionally, the energy storage device 440 may include, but is not limited to, individual batteries, or battery modules, battery packs, battery clusters, power banks, energy storage cabinets / prefabricated energy storage compartments, and other battery integrated systems composed of individual batteries. The actual application form of the energy storage device 440 provided in this application embodiment may be, but is not limited to, the listed products, and may also be other application forms. This application embodiment does not strictly limit the application form of the energy storage device 440.

[0086] Optionally, the individual cell can be, but is not limited to, at least one of cylindrical, prismatic, prismatic, or other shaped cells.

[0087] Optionally, the single cell can be a rechargeable battery, which refers to a single cell that can be recharged after discharge to activate the active materials and continue to be used. The single cell can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, etc., and this application does not specifically limit it.

[0088] Example

[0089] The following examples, embodiments, and comparative examples illustrate the implementation of this application in more detail. Various tests and evaluations were conducted according to the methods described below.

[0090] Example 1

[0091] <Preparation of Negative Electrode Active Materials>

[0092] Secondary petroleum coke particles (Dv50 of 9.5 μm) and asphalt powder (Dv50 of 5 μm) were mixed at a mass ratio of 99.2:0.8 and subjected to thermodynamic kneading at 200℃ to ensure uniform mixing. Then, carbonization and asphalt coating were performed at 900℃. The resulting product was then sieved and demagnetized to obtain a negative electrode active material, which is carbon-coated artificial graphite particles. Its Dv50, OI value, and other parameters are shown in Table 1. The secondary petroleum coke particles were obtained from primary particles through a granulation process.

[0093] <Preparation of Negative Electrode Sheets>

[0094] The prepared negative electrode active material, conductive carbon black (Super-P), CMC, and SBR were mixed in a mass ratio of 96:1:1:2, and deionized water was added to prepare a negative electrode slurry with a solid content of 50wt%, which was then stirred evenly. The negative electrode slurry was uniformly coated onto both sides of a 6μm thick copper foil negative electrode current collector using a die-cutting extrusion coating machine and dried at 85℃. After rolling, slitting, cutting, and welding of tabs, the negative electrode sheet was obtained. The rolling conditions were: a rotation speed of 10m / min and a pressure of 800MPa. The parameters such as the spacing d1 between adjacent tabs, the width d2 of the negative electrode sheet, and the porosity and areal density of the negative electrode active material layer are shown in Table 1.

[0095] <Preparation of the positive electrode>

[0096] Lithium iron phosphate (LiFePO4), conductive agent acetylene black, and binder PVDF were mixed at a mass ratio of 96:2:2. N-methylpyrrolidone (NMP) was then added as a solvent to prepare a positive electrode slurry with a solid content of 60 wt%, and the mixture was stirred evenly. The positive electrode slurry was then uniformly coated onto one surface of a 10 μm thick aluminum foil current collector, dried at 85°C, and subsequently cold-pressed, slit, cut, and welded with tabs to obtain the positive electrode sheet. The areal density of the positive electrode active material layer was 0.250 g / 1540.25 mm. 2 .

[0097] <Preparation of the diaphragm>

[0098] A 16μm thick porous polypropylene (PP) membrane was used as the separator.

[0099] <Preparation of Electrolyte>

[0100] In an argon atmosphere glove box with a moisture content ≤1ppm, ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed at a mass ratio of 3:7. Then, lithium salt LiPF6 was added and dissolved in the solvent. After mixing evenly, an electrolyte was obtained. The concentration of LiPF6 in the electrolyte was 1mol / L.

[0101] <Preparation of Lithium-ion Batteries>

[0102] The positive electrode, separator, and negative electrode obtained above are stacked in sequence, with the separator positioned between the positive and negative electrodes to provide isolation. The resulting cells are then wound to obtain a bare battery cell. The bare battery cell is placed in an aluminum-plastic film packaging bag, vacuum dried, and then injected with electrolyte. After vacuum sealing, settling, formation shaping, and capacity testing, a lithium-ion battery is obtained.

[0103] Example 2

[0104] Except for the preparation of the negative electrode active material, which is different from Example 1, everything else is the same as Example 1.

[0105] <Preparation of Negative Electrode Active Materials>

[0106] Petroleum coke particles (Dv50 of 6 μm) and phenolic resin powder (Dv50 of 8 μm) were mixed at a mass ratio of 98:2 and subjected to thermal dynamic kneading at 120℃ to ensure uniform mixing. Then, carbonization and phenolic resin coating were carried out at 800℃. The prepared product was then sieved and demagnetized to obtain the negative electrode active material. The parameters of the negative electrode active material, such as Dv50, OI value, porosity, and areal density of the negative electrode active material layer, are shown in Table 1.

[0107] Example 3

[0108] Except for the preparation of the negative electrode active material, which is different from Example 1, everything else is the same as Example 1.

[0109] <Preparation of Negative Electrode Active Materials>

[0110] Primary particles of asphalt coke (Dv50 of 5 μm) and micro asphalt powder (Dv50 of 4 μm) were mixed at a mass ratio of 98:2 and subjected to thermal dynamic kneading at 230℃ to ensure uniform mixing. Then, carbonization and asphalt coating were carried out at 1000℃. The prepared product was then sieved and demagnetized to obtain the negative electrode active material. The parameters of the negative electrode active material, such as Dv50, OI value, porosity, and areal density of the negative electrode active material layer, are shown in Table 1.

[0111] Examples 4 to 5

[0112] Except for adjusting the relevant parameters of the negative electrode active material according to Table 1 in the <Preparation of Negative Electrode Active Material> section, the rest is the same as in Example 1.

[0113] In Example 4, the preparation steps of the negative electrode active material include: mixing homogeneous coke primary particles (Dv50 of 6 μm) and phenolic resin micro powder (Dv50 of 8 μm) at a mass ratio of 98:2, and performing thermal dynamic kneading at 120°C to ensure uniform mixing; then carbonizing and coating with phenolic resin at 800°C, and finally sieving and demagnetizing the prepared product to obtain the negative electrode active material. The parameters such as Dv50, OI value, and porosity of the negative electrode active material layer are shown in Table 1.

[0114] The preparation steps of the negative electrode active material in Example 5 include: mixing needle-shaped coke primary particles (Dv50 of 6 μm) and phenolic resin micro powder (Dv50 of 8 μm) at a mass ratio of 98:2, and performing hot dynamic kneading at 120°C to ensure uniform mixing; then carbonizing and coating with phenolic resin at 800°C, and finally sieving and demagnetizing the prepared product to obtain the negative electrode active material. The parameters of the negative electrode active material, such as Dv50, OI value, and porosity of the negative electrode active material layer, are shown in Table 1.

[0115] Examples 6 to 7

[0116] Except for adjusting parameters such as porosity of the negative electrode active material layer according to Table 1 in the <Preparation of Negative Electrode Sheet>, the rest is the same as in Example 1.

[0117] In Example 6, a rolling process was performed at a speed of 10 m / min and a pressure of 900 MPa to obtain the negative electrode sheet.

[0118] In Example 7, a rolling process was performed at a speed of 20 m / min and a pressure of 800 MPa to obtain the negative electrode sheet.

[0119] Examples 8 to 9

[0120] Except for adjusting the OI value, porosity, and areal density of the negative electrode active material according to Table 1 in the <Preparation of Negative Electrode Active Material> section, the rest is the same as in Example 1.

[0121] Examples 10-11

[0122] Except for adjusting the OI value of the negative electrode active material, the porosity, areal density of the negative electrode active material layer, and the inner diameter of the cavity in the central region of the wound structure according to Table 1 in the <Preparation of Lithium-ion Batteries>, the rest is the same as in Example 1.

[0123] Comparative Example 1

[0124] Except for the preparation of the negative electrode active material and the preparation of the negative electrode sheet, which are different from those in Example 1, the rest are the same as in Example 1.

[0125] <Preparation of Negative Electrode Active Materials>

[0126] Petroleum coke particles (Dv50 of 11 μm) and phenolic resin micro powder (Dv50 of 7 μm) were mixed at a mass ratio of 98:2 and subjected to thermal dynamic kneading at 140℃ to ensure uniform mixing. Then, carbonization and phenolic resin coating were carried out at 850℃. The prepared product was then sieved and demagnetized to obtain the negative electrode active material. The parameters of the negative electrode active material, such as Dv50 and OI value, are shown in Table 1.

[0127] <Preparation of Negative Electrode Sheets>

[0128] The prepared negative electrode active material, conductive carbon black (Super-P), CMC, and SBR were mixed in a mass ratio of 96:1:1:2, and deionized water was added to prepare a negative electrode slurry with a solid content of 50wt%, which was then stirred evenly. The negative electrode slurry was uniformly coated onto both sides of a 6μm thick copper foil negative electrode current collector using a die-cutting extrusion coating machine and dried at 85℃. After rolling, slitting, cutting, and welding of tabs, the negative electrode sheet was obtained. The rolling conditions were: a rotation speed of 10m / min and a pressure of 1100MPa. The parameters such as the spacing d1 between adjacent tabs, the width d2 of the negative electrode sheet, and the porosity and areal density of the negative electrode active material layer are shown in Table 1.

[0129] Comparative Example 2

[0130] Except for adjusting the rolling conditions of the roller press in the <Preparation of Negative Electrode Sheet> section to be 10 m / min speed and 600 MPa pressure, the rest is the same as Comparative Example 1. The spacing d1 between adjacent tabs, the width d2 of the negative electrode sheet, and the porosity and areal density of the negative electrode active material layer are shown in Table 1.

[0131] Table 1: Relevant preparation parameters for each example and comparative example

[0132]

[0133]

[0134] Test methods and equipment:

[0135] OI value test of negative electrode active material:

[0136] According to the People's Republic of China Machinery Industry Standard JB / T 4220-2011 "Method for Determination of Lattice Parameters of Artificial Graphite", the X-ray diffraction patterns of the negative electrode active material layer were tested for the (004) plane diffraction lines and (110) plane diffraction lines.

[0137] The experimental conditions are as follows: X-rays are emitted using CuKα radiation, which is removed by a filter or monochromator. The operating voltage of the X-ray tube is 30kV~35kV, and the operating current is 15mA~20mA. The scanning speed of the counter is 1 / 4 (°) / min. When recording the 004 diffraction pattern, the scanning range of the diffraction angle 2θ is 53°~57°. When recording the 110 diffraction pattern, the scanning range of the diffraction angle 2θ is 75°~79°. The peak area obtained from the (004) plane diffraction pattern is denoted as C004. The peak area obtained from the (110) plane diffraction pattern is denoted as C110. The ratio of C004 / C110 of the negative electrode is calculated, which is the OI value of the negative electrode.

[0138] Porosity test of the negative electrode active material layer:

[0139] First, the negative electrode sheet was pretreated (vacuum drying at 45℃ for 2 hours). Then, the negative electrode sheet was cut into 6-8 rectangular sample strips of 1.5cm × 15cm using a mold. The apparent volume V0 was measured (V0 = S × H, where S is the area of ​​a single electrode sheet and H is the total thickness of the sample). A certain amount of inert helium gas was injected into the sample cell of the true density meter. The sample strips were then placed into the sample cell of the true density meter (model AccuPycⅡ1345), and the true volume V0 was measured using the ideal gas law. sample The porosity y of the negative electrode active material layer is calculated using the following expression:

[0140]

[0141] Electrode spacing test:

[0142] The electrode spacing is determined by an automated infrared vision inspection method. Specifically, the bare battery cell (i.e., a lithium-ion battery without electrolyte) is transported to the inspection station via a conveyor belt. After the cell enters the inspection area, the industrial camera triggers a shooting signal through a photoelectric sensor to capture multiple images of the electrode from multiple angles to avoid the electrode being obstructed. In the image processing stage, the system automatically identifies the electrode edges to eliminate interference such as electrode wrinkles and stains, calculates the center distance or edge distance between adjacent electrodes, and selects a measurement benchmark according to process requirements.

[0143] Negative electrode width test:

[0144] Testing and quality assessment are performed using an online visual inspection system and a laser scanning sensor (Yihong Intelligent Fully Automatic Slitting CCD Integrated Machine): The equipment is calibrated in advance using standard width samples to ensure accurate measurement benchmarks; when the negative electrode sheet passes through the detection area, the system automatically positions the edge of the negative electrode sheet to eliminate interference from tabs and burrs, continuously records the width value, measures 10 to 20 points for each sheet, and then takes the average value.

[0145] Areal density test of negative electrode active material layer:

[0146] ① Take samples from the coated negative electrode sheet, covering the head, middle, and tail of the roll, taking 3-5 samples from each. Avoid sampling areas with defects such as tabs, edge wrinkles, missing material, and bulges, and prioritize flat areas with uniform coating. ② Use a circular punching machine to punch circular samples from the negative electrode sheet. Weigh the total mass of the negative electrode sheet samples using a balance and record it as m1. Use the same sampling tool to take samples of the same size from blank copper foil and weigh the substrate mass, recording it as m2. ③ The mass of the active material = m1 - m2, then the areal density of the negative electrode active material layer = (m1 - m2) / the area of ​​the circular sheet.

[0147] Dv50 test of negative electrode active material:

[0148] The Dv50 of the negative electrode active material was measured using a laser diffraction particle size distribution measuring instrument (Malvern Mastersizer 3000) according to the particle size distribution laser diffraction method GB / T19077-2016.

[0149] Test of the inner diameter of the cavity in the central region of the wound structure:

[0150] The test was conducted using an image measuring instrument (model VIP500T-CNC). The lithium-ion battery was fixed on the measuring stage, ensuring that the axis of the cavity hole in the central area was perpendicular to the lens. The image of the cavity in the central area was captured by the lens, and the software automatically identified the edge contour of the cavity. The "Diameter Measurement" function was selected, and the software calculated the maximum diameter, minimum diameter, and average diameter of the cavity.

[0151] Lithium-ion battery room temperature cycle performance test:

[0152] The lithium-ion battery was charged and discharged for the first time in an environment of 25°C: constant power charging was performed at a charging rate of 1C until the upper limit voltage of 3.65V was reached, then constant voltage charging was switched to constant voltage charging. Then constant power discharging was performed at a discharging rate of 1C until the final voltage was 2.5V. The above charge and discharge process was repeated twice, and the discharge capacity of the second cycle was recorded. Then 1000 charge and discharge cycles were performed, and the discharge capacity of the 1000th cycle was recorded.

[0153] Capacity retention rate after 1000 cycles = (Discharge capacity in the 1000th cycle / Charge capacity in the 2nd cycle) × 100%.

[0154] Low-temperature cycle performance test of lithium-ion batteries:

[0155] The lithium-ion battery was charged and discharged for the first time in an environment of -20℃: constant power charging was performed at a charging rate of 0.02C until the upper limit voltage of 3.65V was reached, then constant voltage charging was performed, and then constant power discharging was performed at a discharging rate of 0.02C until the final voltage was 2.5V. The above charge and discharge process was repeated twice, and the discharge capacity of the second cycle was recorded; then 100 charge and discharge cycles were performed, and the discharge capacity of the 100th cycle was recorded.

[0156] Capacity retention rate after 100 cycles = (discharge capacity in the 100th cycle / charge capacity in the 2nd cycle) × 100%.

[0157] Lithium deposition test on negative electrode:

[0158] The prepared lithium-ion battery was charged to 3.65V at a rate of 1C in an environment of -20℃, then discharged to 2.5V at a rate of 1C, and then charged to 3.65V at a rate of 1C for 10 cycles. The lithium-ion battery was then disassembled and the lithium deposition on the surface of the negative electrode was observed.

[0159] Table 2: Performance data for each embodiment and comparative example

[0160]

[0161] As can be seen from Examples 1 to 11 and Comparative Examples 1 to 2, when When the temperature is too high (e.g., in Comparative Example 1), the capacity retention rate of the lithium-ion battery at both room temperature and low temperature is low, and lithium plating occurs on the surface of the negative electrode; when When the capacity is too small (e.g., in Comparative Example 2), the capacity retention rate at room temperature and at low temperature of the lithium-ion battery is also low, and lithium plating occurs on the surface of the negative electrode. However, the capacity retention rate at room temperature and at low temperature of the lithium-ion battery in this application are improved, and no lithium plating occurs on the surface of the negative electrode. It can be seen that when d1, d2, x, and y satisfy the relationship of this application, the lithium-ion battery has better cycle performance, especially low temperature cycle performance, and the lithium plating problem of the negative electrode is improved under low temperature conditions.

[0162] The median particle size of the negative electrode active material and the areal density of the negative electrode active material layer also affect the performance of the negative electrode sheet. As can be seen from Examples 1 to 11, by adjusting the above parameters within the range of this application, and based on the fact that d1, d2, x, and y satisfy the relationships of this application, it is beneficial to obtain a lithium-ion battery with good room temperature cycling performance and low temperature cycling performance.

[0163] The above provides a detailed description of a negative electrode sheet, battery, energy storage device, and electrical equipment disclosed in this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the technical solutions and core inventive points of the embodiments of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A negative electrode sheet, characterized in that, The negative electrode sheet includes a negative current collector, at least one side of which has a negative active material layer, the negative active material layer comprising a negative active material, and a plurality of tabs are disposed along the length of the negative electrode sheet. The negative electrode sheet satisfies the relationship: 1.6 ≤ ≤7.4; Wherein, d1 represents the distance between adjacent tabs, in cm; d2 represents the width of the negative electrode plate, in cm; x represents the OI value of the negative electrode active material; y represents the porosity of the negative electrode active material layer; 6≤x≤15, 0.2≤y≤0.35, 0.1≤d1≤0.7, 10≤d2≤24.

2. The negative electrode sheet according to claim 1, characterized in that, The negative electrode sheet satisfies the following relationship: 2.5 ≤ ≤7.

3. The negative electrode sheet according to claim 1, characterized in that, The areal density of the negative electrode active material layer is CW, 0.11 g / 1540.25 mm. 2 ≤CW≤0.14 g / 1540.25mm 2 .

4. The negative electrode sheet according to claim 1, characterized in that, The median particle size of the negative electrode active material is Dv50, where 5 μm ≤ Dv50 ≤ 12 μm.

5. A battery, characterized in that, Includes the negative electrode sheet as described in any one of claims 1 to 4.

6. The battery according to claim 5, characterized in that, The battery has a wound structure, and the central region of the wound structure has a cavity with an inner diameter of L, where 5mm ≤ L ≤ 8mm.

7. An energy storage device, characterized in that, It includes a housing and at least one battery as described in claim 5 or 6, the battery being housed within the housing.

8. An electrical appliance, characterized in that, The device includes the energy storage device of claim 7, wherein the energy storage device supplies power to the electrical equipment.

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