Energy storage apparatus and electric device

Abstract

An energy storage apparatus (100) and an electric device (400), which relate to the technical field of energy storage. The energy storage apparatus (100) comprises: an electrode assembly (20), which comprises a positive electrode sheet (21), a negative electrode sheet (22) and a separator (23), wherein the positive electrode sheet (21) comprises a current collector (211) and an active material layer (212), the active material layer (212) contains first lithium-containing compounds (Li1) and second lithium-containing compounds (Li2), and the second lithium-containing compounds (Li2) are lithium-replenishment particles and each comprise a lithium-replenishment core (Li21) and a shell (Li22); and a connected region (AA) and a separated region (BB) are formed between the lithium-replenishment core (Li21) and the shell (Li22), and in a cross section of the positive electrode sheet (21), the ratio of the path length of the shell (Li22) of each lithium-replenishment particle in the connected region (AA) to the total perimeter of the shell ranges from 5% to 45%.

Description

Energy storage devices and electrical equipment

[0001] Cross-references

[0002] This disclosure claims priority to Chinese patent application number 202410149534.4 filed on February 2, 2024, entitled “Energy Storage Device and Electrical Equipment,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the field of energy storage technology, and in particular to an energy storage device and electrical equipment. Background Art

[0004] Secondary batteries, also known as rechargeable batteries or storage batteries, are batteries that can be recharged after discharge to reactivate the active materials and continue to be used. Their recyclable nature has made them a key power source for electrical devices. As demand for secondary batteries grows, so too are demands on their performance, particularly cycle life.

[0005] To improve the cycle life of secondary batteries, prior art has proposed pre-replenishing lithium during the battery manufacturing process to reduce lithium consumption during the formation stage. However, after careful research, researchers have discovered that even after lithium replenishment, some areas may still appear purple due to poor lithium replenishment. Furthermore, some areas may experience lithium deposition due to excessive lithium replenishment, which can affect the battery's cycle life and even increase safety risks. Summary of the Invention

[0006] A main purpose of the present application is to provide an energy storage device and electrical equipment that can improve cycle life.

[0007] To achieve the above application objectives, this application adopts the following technical solutions:

[0008] According to one aspect of the present application, an energy storage device is provided, comprising: an electrode assembly including a stacked positive electrode sheet, a negative electrode sheet, and a separator; the positive electrode sheet including a current collector and an active material layer located on a surface of the current collector, the active material layer comprising a first lithium-containing compound and a second lithium-containing compound in granular form, the first lithium-containing compound being a positive electrode active material, the second lithium-containing compound being a lithium-supplementing particle, the lithium-supplementing particle including a lithium-supplementing core and a shell covering the lithium-supplementing core; a connection region and a separation region being formed between the lithium-supplementing core and the shell, the spacing between the lithium-supplementing core and the shell in the connection region being less than or equal to 5 nanometers, and the spacing between the lithium-supplementing core and the shell in the separation region being greater than 5 nanometers, the lithium-supplementing particles in the active material layer being within a cross-section of the positive electrode sheet, the ratio of the path length of the shell of the lithium-supplementing particle in the connection region to the total circumference of the shell being greater than or equal to 5% and less than or equal to 45%.

[0009] In the embodiment of the present application, the ratio of the path length of the shell of the lithium-replenishing particles in the connection area to the total circumference of the shell is set to be greater than or equal to 5% and less than or equal to 45%, so as to ensure the uniformity of the release of lithium ions by the lithium-replenishing particles in the active material layer during the formation stage of the energy storage device, and to ensure that the lithium-replenishing particles release sufficient lithium ions to form a solid electrolyte interface film, thereby avoiding local lithium deposition and local purple spots on the positive electrode sheet 21 of the energy storage device 100, so as to ensure the cycle life of the energy storage device; at the same time, it can avoid the situation where the lithium-replenishing particles have a smaller connection area and form fewer lithium ion transmission paths, resulting in poor subsequent lithium replenishment effect.

[0010] According to one aspect of the present application, an electric device is provided, which includes the energy storage device described in the above aspect, and the energy storage device supplies power to the electric device.

[0011] In the embodiments of the present application, in combination with the energy storage device described above, during the use of the electrical equipment, it is convenient to improve the working stability of the electrical equipment and extend the working time of the electrical equipment.

[0012] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The above and other features and advantages of the present application will become more apparent by describing in detail example embodiments thereof with reference to the accompanying drawings.

[0014] FIG1 is a schematic structural diagram of a household energy storage system according to an exemplary embodiment.

[0015] FIG2 is a schematic cross-sectional view of an electrode assembly according to an exemplary embodiment.

[0016] FIG3 is a schematic cross-sectional view of an energy storage device according to an exemplary embodiment.

[0017] FIG4 is a schematic diagram showing a cross-sectional structure of a positive electrode sheet according to an exemplary embodiment.

[0018] FIG5 is an electron microscope image of a first observation area within a cross-section of a positive electrode sheet according to an exemplary embodiment.

[0019] FIG6 is an electron microscope image of a second observation area within a cross-section of a positive electrode sheet according to an exemplary embodiment.

[0020] FIG7 is a schematic structural diagram showing an electric device according to an exemplary embodiment.

[0021] Among them, the figure numbers are explained as follows: 100, energy storage device; 200, electric energy conversion device; 300, user load; 400, electrical equipment; 10, shell; 20, electrode assembly; 30, end cover unit; 11, accommodating cavity; 21, positive electrode sheet; 22, negative electrode sheet; 23, diaphragm; 31, cover plate; 32, electrode terminal; 211, current collector; 212, active material layer; Li1, first lithium-containing compound; Li2, second lithium-containing compound; Li21, lithium-supplementing core; Li22, shell; AA, connection area; BB, separation area. DETAILED DESCRIPTION

[0022] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concepts of the example embodiments to those skilled in the art. Like reference numerals in the figures represent like or similar structures, and thus their detailed description will be omitted.

[0023] Since the energy people need is highly temporal and spatial, in order to make rational use of energy and improve energy utilization, it is necessary to use a medium or device to store one form of energy in the same form or convert it into another form of energy, and then release it in a specific form of energy based on future application needs.

[0024] Current green energy sources mainly include solar energy, wind energy, etc. However, solar energy and wind energy generally have problems of strong intermittency and large volatility, which will cause unstable voltage of the green power grid (insufficient electricity during peak hours and too much electricity during low hours). Unstable voltage will cause damage to electricity. Therefore, it may cause the problem of "wind and solar power curtailment" due to insufficient electricity demand or insufficient grid acceptance capacity.

[0025] To address the issue of insufficient electricity demand or insufficient grid capacity, energy storage devices are essential. These devices convert electrical energy into other forms of energy through physical or chemical means, storing it. When needed, the stored energy is converted back into electricity and released. Simply put, an energy storage device acts like a large "power bank," storing electricity when there's sufficient solar or wind energy and releasing it when needed.

[0026] Currently, energy storage (i.e., energy storage) has a wide range of application scenarios, including power generation-side energy storage, grid-side energy storage, renewable energy grid-connected energy storage, and user-side energy storage. The corresponding types of energy storage devices include:

[0027] (1) Large energy storage containers used in grid-side energy storage scenarios can serve as high-quality active and reactive power regulation power sources in the grid, achieving load matching of electricity in time and space, enhancing the ability to absorb renewable energy, and are of great significance in grid system backup, alleviating peak load power supply pressure, and peak and frequency regulation;

[0028] (2) The main operating mode of small and medium-sized energy storage cabinets used in industrial and commercial energy storage scenarios (banks, shopping malls, etc.) on the user side and small household energy storage boxes used in home energy storage scenarios on the user side is "peak shaving and valley filling". Since there is a large price difference in electricity prices at peak and valley locations according to electricity demand, after users have energy storage equipment, in order to reduce costs, they usually charge the energy storage cabinets / boxes during the low electricity price period; during the peak electricity price period, the electricity in the energy storage equipment is discharged for use to achieve the purpose of saving electricity bills. In addition, in remote areas and areas with high incidence of natural disasters such as earthquakes and hurricanes, the existence of household energy storage devices is equivalent to users providing themselves and the power grid with backup power, eliminating the inconvenience caused by frequent power outages due to disasters or other reasons.

[0029] Taking the household energy storage scenario in user-side energy storage as an example, Figure 1 shows a household energy storage system. The household energy storage system includes an energy storage device 100, an electric energy conversion device 200 (such as a photovoltaic panel), and a user load 300 (such as a street lamp, household appliances, etc.). The energy storage device 100 is a small energy storage box that can be mounted on an outdoor wall. Specifically, the electric energy conversion device 200 can convert solar energy into electrical energy during periods of low electricity prices and store it in the energy storage device 100. The energy can then be supplied to the user load 300 for use during peak electricity prices or during power outages.

[0030] In conjunction with the aforementioned physical or electrochemical energy storage, taking electrochemical energy storage as an example, energy storage device 100 includes at least one chemical battery, utilizing the chemical elements within the battery as an energy storage medium, with the charging and discharging process achieved through chemical reactions or changes in the storage medium. Simply put, the electrical energy generated by solar or wind energy is stored in at least one set of chemical batteries through chemical reactions or changes in the storage medium. When external power usage reaches a peak, the energy stored in the at least one set of chemical batteries is released through chemical reactions or changes in the storage medium, or transferred to areas with power shortages for reuse.

[0031] The present embodiment provides an energy storage device 100, which may be, but is not limited to, a single cell (secondary battery), as well as a battery module, battery pack, battery system, etc. composed of single cells. The single cell may be a lithium-ion battery, a lithium-sulfur battery, a sodium-lithium-ion battery, a sodium-ion battery, a magnesium-ion battery, etc. The single cell may be cylindrical, flat, or rectangular. Furthermore, the single cell may be a soft-pack battery or a battery with a housing, etc., which is not limited in the present embodiment.

[0032] Taking the energy storage device 100 as a single cell as an example, the energy storage device 100 includes an electrode assembly 20, as shown in Figure 2. The electrode assembly 20 includes a stacked positive electrode sheet 21, a negative electrode sheet 22 and a separator 23, and the separator 23 is located between the positive electrode sheet 21 and the negative electrode sheet 22. The positive electrode sheet 21 and the negative electrode sheet 22 have positive and negative tabs, respectively, to facilitate series and parallel connection with other single cells through the positive and negative tabs.

[0033] FIG3 illustrates a schematic structural diagram of an energy storage device 100 provided in an embodiment of the present application. As shown in FIG3 , the energy storage device 100 includes, in addition to the electrode assembly 20, a housing 10 and an end cap unit 30 . The housing 10 includes a receiving cavity 11 with an opening. The end cap unit 30 seals the opening of the receiving cavity 11 . The electrode assembly 20 is accommodated in the receiving cavity 11 .

[0034] The shell 10 may be a cylindrical structure with one end open. In this case, the energy storage device 100 includes an end cover unit 30 to seal one opening of the shell 10 through the end cover unit 30. Of course, the shell 10 may also be a cylindrical structure with both ends open. In this case, the energy storage device 100 includes an end cover unit 30 and a cover plate 31, or includes two end cover units 30, so that the two openings of the shell 10 are sealed through the end cover unit 30 and the cover plate 31, or the two end cover units 30 respectively.

[0035] Among them, the end cover unit 30 includes an end cover body and an electrode terminal 32. The electrode terminal 32 is penetrated on the end cover body, and one end is connected to the electrode assembly 20, and the other end is exposed outside the accommodating cavity 11 to serve as the output end of the energy storage device 100; the end cover body can also be provided with an explosion-proof valve and / or an injection hole. The explosion-proof valve is used to discharge the gas accumulated in the accommodating cavity 11 to improve the safety of the use of the energy storage device 100, and the injection hole is used to inject electrolyte into the accommodating cavity 11 to achieve infiltration of the electrode assembly 20.

[0036] In which, in combination with the electrode assembly 20 described above, the positive electrode tabs and negative electrode tabs respectively possessed by the positive electrode sheet 21 and the negative electrode sheet 22 can be located at different ends of the electrode assembly 20. At this time, one of the positive electrode tab and the negative electrode tab is connected to the electrode terminal 32 included in the end cover unit 30, and the other is connected to the bottom of the shell 10 or the electrode terminal 32 included in the other end cover unit 30, so as to realize the electrical energy output of the electrode assembly 20 through the electrode terminal 32 of the end cover unit 30 and the bottom of the shell 10, or through the electrode terminals 32 of the two end cover units 30.

[0037] Furthermore, the energy storage device 100 also includes a metal adapter, which can be used to connect the electrode tab of the electrode assembly 20 and the electrode terminal 32 of the end cover unit 30 to ensure the stability of the connection between the electrode tab and the electrode terminal 32 while ensuring the overcurrent capacity.

[0038] In the related art, lithium replenishing materials are usually added during the production process of the positive electrode sheet 21 to reduce the consumption of lithium ions in the positive electrode active material caused by the formation of a solid electrolyte interface film during the formation stage of the energy storage device 100, thereby reducing the irreversible capacity of the energy storage device 100 and facilitating the improvement of the cycle life of the energy storage device 100. However, after careful research, technicians found that although the lithium replenishing particles included in the lithium replenishing material can achieve the replenishment of lithium ions, after disassembling the energy storage device 100 after use, it was found that some areas on the negative electrode sheet 22 of the electrode assembly 20 still had purple spots due to poor lithium replenishment effect, and some areas had lithium deposition due to excessive lithium replenishment. To this end, the embodiment of the present application provides an energy storage device 100, which includes a lithium replenishing material added to the positive electrode sheet 21. On the basis of uniform distribution, it can effectively ensure the uniformity of lithium replenishment in various areas on the positive electrode sheet 21, so as to effectively improve the cycle life of the energy storage device 100 and reduce safety hazards.

[0039] FIG4 illustrates a cross-sectional structural diagram of a positive electrode sheet 21 provided in an embodiment of the present application. As shown in FIG4 , the positive electrode sheet 21 includes: a current collector 211 and an active material layer 212 located on the surface of the current collector 211 .

[0040] The positive electrode sheet 21 may have an active material layer 212 on one surface of the current collector 211, or on both surfaces of the current collector 211. Compared to the case where the active material layer 212 is provided on one surface of the current collector 211, the case where the active material layer 212 is provided on both surfaces of the current collector 211 can effectively increase the lithium ion content per unit volume of the positive electrode sheet 21, thereby effectively increasing the specific capacity of the energy storage device 100 including the positive electrode sheet 21. At the same time, by reducing the amount of the current collector 211, the energy storage device 100 can be made lighter.

[0041] From the electron microscope image of the first observation area within the cross-section of the positive electrode sheet 21 shown in Figure 5 and the electron microscope image of the second observation area within the cross-section of the positive electrode sheet 21 shown in Figure 6, it can be seen that the active material layer 212 includes a granular first lithium-containing compound Li1 and a second lithium-containing compound Li2, the first lithium-containing compound Li1 is the positive electrode active material, the second lithium-containing compound Li2 is a lithium-supplementing particle, and the lithium-supplementing particle includes a lithium-supplementing core Li21 and a shell Li22 covering the lithium-supplementing core Li21, thereby achieving lithium ion replenishment through the second lithium-containing compound Li2 included in the active material layer 212, reducing the consumption of lithium ions in the positive electrode active material caused by the formation of a solid electrolyte interface film.

[0042] The electron microscope images shown in Figures 5 and 6 are images of regions observed through the microscope window at an accelerating voltage of 5 kV, a working distance of 4.3 mm, an aperture size of 30 μm, and a magnification of 5,000x. Furthermore, the cross-section of the positive electrode sheet 21 can be a straight cross-section of the positive electrode sheet 21, i.e., a cross-section obtained by shearing the positive electrode sheet 21 in a direction perpendicular to its length. Alternatively, it can be an oblique cross-section of the positive electrode sheet 21, i.e., a cross-section obtained by shearing the positive electrode sheet 21 in a direction intersecting its length. The observation area within the cross-section (e.g., the first observation area and the second observation area described above) can be selected by first confirming the distribution area of ​​the granular second lithium-containing compound Li2 within the cross-section using a microscope. The observation area can then be confirmed by combining the distribution area of ​​the lithium-supplementing particles with the observation area at an appropriate magnification (e.g., 5,000x). The ratio of the observed area of ​​the lithium-supplementing particles within the observation area to the area of ​​the observation area should be greater than or equal to 0.3 and less than or equal to 0.7.

[0043] Among them, the first lithium-containing compound Li1 can be a positive electrode active material, such as at least one of LiFePO4, LiCoO2, LiMn2O4, and NCM. This can reduce the selection criteria of the first lithium-containing compound Li1 and reduce the production cost of the active material layer 212. At the same time, the electrical properties of the first lithium-containing compound Li1 can be improved by combining multiple types of positive electrode active materials.

[0044] For the lithium supplement core Li21 included in the lithium supplement particles in the second lithium-containing compound Li2, it can be Li 1+r M 1-p N p O 4-s B s , 0.1 < r < 6.1, 0 ≤ p < 0.99, 0 ≤ s < 0.1, M and N are at least one of the elements Fe, Co, Ni, Ti, Zn, Mg, Al, Mn, V, Cr, Zr, Cu, Nb, Ta, W, Zr, Y, La respectively, and B is at least one of the elements S, N, F, Cl, Br. Exemplarily, the lithium supplement core Li21 is Li5FeO4 (M is the element Fe, and both p and s take the value of 0).

[0045] Since the lithium content of the second lithium-containing compound Li2 is greater than that of the first lithium-containing compound Li1, when manufacturing the active material layer 212, a certain amount of the second lithium-containing compound Li2 can be directly used to replace the same amount of the first lithium-containing compound Li1, so as to achieve the lithium supplement effect while avoiding adjusting the contents of other components, which is convenient for simplifying the preparation of the active material layer 212. The lithium content involved in this application is the content of lithium ions per unit mass, and this unit mass can be the mass of the substance or the amount of substance (i.e., molar mass).

[0046] Optionally, in the cross-section of the lithium supplement particles, the ratio of the total length of the outer contour of the lithium supplement core Li21 to the circumference of the smallest circumscribed circle of the outer contour is greater than or equal to 0.125 and less than or equal to 1. Exemplarily, the ratio of the circumference of the lithium supplement core Li21 to the circumference of the smallest circumscribed circle is 0.125, 0.25, 0.5, 1. In this way, the roundness of the lithium supplement core Li21 can be ensured, and then the uniformity of the coating of the outer shell Li22 can be ensured when manufacturing the lithium supplement particles, the deintercalation effect of lithium ions in the lithium supplement core Li21 can be ensured, and at the same time, the risk of the outer shell Li22 cracking caused by the deintercalation of lithium ions in the lithium supplement core Li21 can be reduced. In addition, the more uniform the coating of the outer shell Li22 is, the more uniform the lithium supplement effect of the lithium supplement core Li21 will be, and then the uniformity of the lithium supplement effect of the lithium supplement particles can be ensured.

[0047] Furthermore, the ratio of the total length of the outer contour of the lithium supplement core Li21 to the circumference of the smallest circumscribed circle of the outer contour is greater than or equal to 0.25 and less than or equal to 0.9. In this way, the roundness of the lithium supplement core Li21 can be further ensured to further ensure the deintercalation effect of lithium ions in the lithium supplement core Li21, and at the same time, the risk of the outer shell Li22 cracking can be further reduced. Exemplarily, the ratio of the total length of the outer contour of the lithium supplement core Li21 to the circumference of the smallest circumscribed circle is 0.25, 0.3, 0.35, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, etc.

[0048] Among them, for the total length of the outer contour of the lithium-replenishing core Li21 in the cross-section of the positive electrode sheet 21, and the circumference of the minimum circumscribed circle of the outer contour, the cross-sectional structure of the lithium-replenishing particles in Figure 5 or Figure 6 described above can be combined to mark the outer contour L1 of the lithium-replenishing core Li21 and determine the length of each of the multiple segments of the outer contour L1 based on the established coordinate system to determine the total length of the outer contour L1; and determine the minimum circumscribed circle L2 of the outer contour L1 based on the established coordinate system, and determine the circumference of the minimum circumscribed circle L2.

[0049] Optionally, the median particle size of the lithium-supplementing core Li21 is greater than or equal to 3 microns and less than or equal to 10 microns, that is, the particle size Dv50 of the lithium-supplementing core is greater than or equal to 3 microns and less than or equal to 10 microns. By limiting the median particle size of the lithium-supplementing core Li21, the size of the lithium-supplementing particles is limited, thereby ensuring uniform distribution of the lithium-supplementing particles within the active material layer 212 and ensuring uniform lithium-supplementing effect. This also prevents the lithium-supplementing effect from being poor due to instability in air when the lithium-supplementing particles are too small, which could lead to capacity loss in the energy storage device 100. It also prevents the lithium-supplementing effect from being poor due to poor kinetics when the lithium-supplementing particles are too large, which could lead to capacity reduction in the energy storage device 100.

[0050] For example, the median particle size of the lithium-supplementing core Li21 is 3 microns, 4 microns, 5 microns, 6 microns, 7 microns, 8 microns, 9 microns, 10 microns, etc. Of course, the median particle size of the lithium-supplementing core can also be slightly smaller than 3 microns or slightly larger than 10 microns, and this embodiment of the application is not limited to this.

[0051] The outer shell Li22 included in the lithium-supplementing particles of the second lithium-containing compound Li2 can have a single coating layer structure or a multi-coating layer structure. When the outer shell Li22 has a single coating layer structure, the outer shell Li22 can be an oxide coating layer or a conductive coating layer. When the outer shell Li22 has a multi-coating layer structure, the outer shell Li22 can have an oxide coating layer and a conductive coating layer, with the oxide coating layer being located in the inner layer.

[0052] Among them, the oxide coating layer can be M x O y Coating layer; M is at least one of the elements Fe, Co, Ni, Ti, Zn, Mg, Al, Mn, V, Cr, Zr, Cu, Nb, Ta, W, Zr, Y, and La, with 1 ≤ x ≤ 3 and 1 ≤ y ≤ 5. For example, an Al2O3 coating layer. The conductive coating layer may be a carbon coating layer or a superionic conductor coating layer. For example, a graphite coating layer may be used.

[0053] Among them, the specific structure of the shell Li22 can be set in combination with the median particle size of the lithium-replenishing core Li21. Specifically, for the lithium-replenishing core Li21 with a larger specific surface area, external gas, moisture, etc. are more likely to enter it, causing CO2 and moisture to react with the lithium-replenishing core Li21, resulting in a decrease in the capacity of the lithium-replenishing core Li21, thereby reducing the amount of lithium replenishment. In this case, an oxide coating layer can be coated on the surface of the lithium-replenishing core Li21 to form protection, thereby ensuring the lithium replenishment effect. For the lithium-replenishing core Li21 with a smaller specific surface area, its conductivity is relatively low. In this case, a conductive coating layer can be coated on the surface of the lithium-replenishing core Li21 to improve the conductivity. For the lithium-replenishing core Li21 with a moderate specific surface area, an oxide coating layer and a conductive coating layer can be coated on the surface of the lithium-replenishing core Li21 in sequence to form protection while improving conductivity.

[0054] The specific surface area of ​​the lithium-replenishing core Li21 decreases with increasing particle size, while the specific surface area increases with decreasing particle size. For example, when the median particle size of the lithium-replenishing core Li21 is less than or equal to 3 microns, only an oxide coating layer may be provided; when the median particle size of the lithium-replenishing core Li21 is greater than or equal to 10 microns, only a conductive coating layer may be provided; and when the median particle size of the lithium-replenishing core Li21 is greater than or equal to 3 microns and less than or equal to 10 microns, both an oxide coating layer and a conductive coating layer may be provided. Of course, it is also possible to directly provide both an oxide coating layer and a conductive coating layer without regard to the median particle size of the lithium-replenishing core Li21, and this is not limited in the present embodiments.

[0055] Taking the shell Li22 including an oxide coating layer and a carbon coating layer as an example, the preparation method of the second lithium-containing compound Li2 can be: a lithium source and a precursor Fe source are mixed in a molar ratio of 5 to 6:1, and after ball milling, they are sintered at a high temperature of 600 to 800 degrees Celsius for 15 to 20 hours under a protective gas (such as nitrogen) to obtain a granular lithium-replenishing core Li21. The lithium-replenishing core Li21 is then first coated with a layer of oxide by ALD (Atomic Layer Deposition), CVD (Chemical Vapor Deposition), PLD (Pulsed Laser Deposition), etc. to obtain an oxide coating layer, which is then mixed with an organic carbon source and sintered at a high temperature of 300 to 500 degrees Celsius for 4 to 6 hours to obtain a second lithium-containing compound Li2 having an oxide coating layer and a carbon coating layer.

[0056] Among them, after sintering at high temperature to obtain the granular lithium-replenishing core Li21, through ball milling, screening and other operations, particles with a ratio of the total length of the inner and outer contours of the particle cross-section to the circumference of the minimum circumscribed circle of the outer contour greater than or equal to 0.125 and less than or equal to 1 can be obtained as the lithium-replenishing core Li21. At the same time, the lithium-replenishing core Li21 with a median particle size greater than or equal to 3 microns and less than or equal to 10 microns can also be obtained.

[0057] Among them, for lithium-replenishing particles including a carbon coating layer, combined with the above-mentioned method for preparing the second lithium-containing compound Li2, the ratio of the organic carbon source can be adjusted when the lithium-replenishing core Li21 is mixed with the organic carbon source, so that the mass proportion of the carbon content in the prepared second lithium-containing compound Li2 is greater than or equal to 0.5% and less than or equal to 4%, so as to avoid the second lithium-containing compound Li2 having a low carbon content and affecting the conductive properties of the second lithium-containing compound Li2 in the active material layer 212, thereby affecting the deintercalation of lithium ions on the lithium-replenishing core Li21, and at the same time avoid the carbon coating layer being too thick due to the high carbon content in the second lithium-containing compound Li2, thereby affecting the deintercalation of lithium ions on the lithium-replenishing core Li21.

[0058] Furthermore, the ratio of the organic carbon source can be adjusted so that the mass percentage of carbon in the second lithium-containing compound Li2 is greater than or equal to 0.5% and less than or equal to 3.5%. For example, the mass percentage of carbon in the second lithium-containing compound Li2 is 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, etc.

[0059] In addition, for the shell Li22 (oxide coating layer and / or conductive coating layer) that covers the lithium-supplementing core Li21, in order to prevent the shell Li22 from rupturing and causing external air to enter the lithium-supplementing core Li21 and react, thereby reducing the lithium ion deintercalation ability of the lithium-supplementing core Li21, the shell Li22 of the lithium-supplementing particle is a continuous spherical structure. That is, as shown in Figure 5 or Figure 6, in the electron microscope image of the cross-section of the positive electrode sheet 21, the cut edge of the shell Li22 is a continuous structure. In this way, the shell Li22 can be ensured to completely cover the lithium-supplementing core Li21, avoiding the reaction between the lithium-supplementing core Li21 and the external air. For example, in combination with the above-mentioned method for producing the second lithium-containing compound Li2, the ratio of the precursor Fe source and the ratio of the organic carbon source can be adjusted to ensure that the shell Li22 of the lithium-supplementing particle is a continuous spherical structure.

[0060] It can be understood that the spherical structure described herein can be a regular spherical structure or a spherical-like structure similar to a sphere.

[0061] Furthermore, the thickness of the outer shell Li22 of the lithium-supplementing particle is greater than or equal to 30 nanometers and less than or equal to 200 nanometers. This prevents the thin outer shell Li22 from cracking during the formation or charge-discharge phases of the energy storage device 100, prevents external gases and moisture from easily entering the outer shell, which could cause CO2 and moisture to react with the inner core Li21, and prevents the thick outer shell Li22 from affecting the intercalation and deintercalation of lithium ions in the inner core Li21 and the infiltration of the electrolyte into the inner core Li21. Furthermore, it prevents the problem of a relatively small lithium ion mass ratio in the lithium-supplementing particle due to a thick outer shell Li22.

[0062] For example, in combination with the above-mentioned method for manufacturing the second lithium-containing compound Li2, the thickness of the shell Li22 can be ensured to be 30 nanometers, 50 nanometers, 100 nanometers, 150 nanometers, 200 nanometers, etc. by adjusting the ratio of the precursor Fe source and the ratio of the organic carbon source.

[0063] It should be noted that the thickness of the outer shell Li22 can vary in different regions. In this case, the thickness can be determined by combining the minimum and maximum thicknesses of the outer shell Li22, as long as the minimum and maximum thicknesses are within the above ranges. For example, the minimum thickness of the outer shell Li22 is 45 nanometers and the maximum thickness is 180 nanometers.

[0064] In some embodiments, the particle size distribution of the lithium-replenishing particles in the second lithium-containing compound Li2 satisfies (Dv99-Dv10) / Dv50 is less than or equal to 4, that is, the particle size distribution of the lithium-replenishing particles satisfies that the difference between the particle size when the volume share is 99% and the particle size when the volume share is 10% is less than or equal to 4 times the median particle size.

[0065] In this way, the uniformity of the particle size of the lithium-replenishing particles in the second lithium-containing compound Li2 can be ensured, avoiding large differences in the particle size of the lithium-replenishing particles, which may lead to concentrated lithium ion distribution in the active material layer 212 due to larger lithium-replenishing particles in local areas, and poor lithium-replenishing effect due to smaller lithium-replenishing particles in local areas; at the same time, the uniformity of lithium ion insertion and extraction in each lithium-replenishing particle is ensured.

[0066] The smaller the value of (Dv99 - Dv10) / Dv50, the more uniform the size of the lithium-supplementing particles. In this case, the lithium-supplementing core Li21 of the lithium-supplementing particles releases lithium ions more evenly. For example, the value of (Dv99 - Dv10) / Dv50 can be 1, 2, 3, 4, etc.

[0067] In other embodiments, the particle size distribution of the lithium-replenishing particles in the second lithium-containing compound Li2 satisfies Dv90 less than or equal to 35 microns and Dv10 greater than or equal to 1 micron, so as to limit the overall size of the lithium-replenishing particles in the second lithium-containing compound Li2, thereby further ensuring the uniformity of the particle size of the lithium-replenishing particles in the second lithium-containing compound Li2.

[0068] For example, the value of Dv90 is 12 microns, 15 microns, 18 microns, 21 microns, 24 microns, 27 microns, 30 microns, 33 microns, 35 microns, etc.; the value of Dv10 is 1 micron, 1.5 microns, 2 microns, 2.5 microns, 3 microns, 3.5 microns, 4 microns, etc.

[0069] It should be noted that in the process of preparing the second lithium-containing compound Li2, particle size screening can be carried out so that the particle size distribution of the lithium-replenishing particles in the second lithium-containing compound Li2 satisfies (Dv99-Dv10) / Dv50 is less than or equal to 4, and at the same time Dv90 is less than or equal to 35 microns, and Dv10 is greater than or equal to 1 micron, so as to further ensure the particle size uniformity of the lithium-replenishing particles in the second lithium-containing compound Li2.

[0070] In the embodiment of the present application, in addition to the first lithium-containing compound Li1 and the second lithium-containing compound Li2, the active material layer 212 also includes at least a conductive agent, a binder and a solvent. The conductive agent can be at least one of conductive carbon black, conductive graphite, graphene, carbon nanotubes and carbon fibers, etc. The binder can be at least one of styrene-butadiene rubber, polyvinylidene fluoride, polyvinyl alcohol, polyethylene acrylic acid, polyacrylate, polytetrafluoroethylene, etc. The solvent can be at least one of deionized water, N-methylpyrrolidone, etc.

[0071] Optionally, the mass ratio of the first lithium-containing compound Li1 to the second lithium-containing compound Li2 in the active material layer 212 can be 89-98.7:0.3-5, to ensure the content of the second lithium-containing compound Li2 in the active material layer 212, thereby ensuring the lithium replenishment effect of the energy storage device 100. For example, the mass ratio of the first lithium-containing compound Li1 to the second lithium-containing compound Li2 is 89:5.0, 91:4.0, 92:3.0, 94:2.0, 96:0.5, 98.7:0.3, etc.

[0072] Furthermore, the mass ratio of the first lithium-containing compound Li1 to the second lithium-containing compound Li2 in the active material layer 212 can be 92-96.5:0.5-3, so as to ensure the content of the second lithium-containing compound Li2 in the active material layer 212, thereby ensuring the lithium replenishment effect of the energy storage device 100 and avoiding the lithium plating phenomenon.

[0073] In some embodiments, the active material layer 212 can be prepared by: mixing the first lithium-containing compound Li1, the second lithium-containing compound Li2, the conductive agent, and the binder at a mass ratio of 92% to 96.5%: 0.5% to 3%: 0.2% to 2%: 1% to 3% at high speed, and then adding a solvent and stirring for a second time to obtain a positive electrode slurry with a solid content of 50% to 70%; then coating the positive electrode slurry on one side of the current collector 211 (such as aluminum foil) at a single-sided coating density of 0.16 mg / mm2 to 0.26 mg / mm2, and then drying at a temperature of 90 degrees Celsius to 110 degrees Celsius, and then compacting to obtain an active material layer 212 with a compaction density of 2.3 to 2.7 g / cm3.

[0074] In this way, through the above preparation process, the uniform distribution of the second lithium-containing compound Li2 in the active material layer 212 and the lithium replenishment effect of the second lithium-containing compound Li2 are ensured, and the phenomenon of excessive aggregation of the lithium replenishment material in a local area on the active material layer 212 and the occurrence of lithium precipitation, or the phenomenon of poor lithium replenishment due to excessive lithium replenishment, is avoided. Among them, the stirring speed during the two stirrings can be greater than or equal to 1000 rpm, for example, the stirring speed can be 1000 rpm, 1500 rpm, 2000 rpm, and 2500 rpm. Of course, the two stirring speeds can also be slightly less than 1000 rpm, for example, 900 rpm and 800 rpm, as long as the uniform distribution of the second lithium-containing compound Li2 in the active material layer 212 can be ensured.

[0075] The mass proportion of the second lithium-containing compound Li2 in the active material layer 212 is greater than or equal to 0.5% and less than or equal to 3%, so as to avoid the second lithium-containing compound Li2 in the active material layer 212 having a low content and affecting the lithium replenishment effect, and to avoid the second lithium-containing compound Li2 in the active material layer 212 having a high content and causing excessive lithium replenishment and local lithium precipitation, and to avoid the first lithium-containing compound Li1 in the active material layer 212 having a low mass proportion and causing a decrease in energy density. For example, the mass proportion of the second lithium-containing compound Li2 in the active material layer 212 is 0.5%, 1.0%, 1.5%, 2%, 2.5%, 3%, etc.

[0076] In this application, after the positive electrode sheet 21 is fabricated, the negative electrode sheet 22 and the separator 23 are combined to form the electrode assembly 20, which is then assembled with the housing 10 and the end cap unit 30 to form the energy storage device 100. The assembled energy storage device 100 typically undergoes a formation phase to form a good solid electrolyte interface film before charging and discharging to provide power to the electrical device 400.

[0077] Among them, the production process of the negative electrode sheet 22 is: the negative electrode active material (such as artificial graphite), the thickener (such as sodium carboxymethyl cellulose CMC), the conductive agent (such as conductive carbon black Super-P) and the binder (such as styrene-butadiene rubber emulsion SBR) are mixed in a mass ratio of 96:1:1:2, and then deionized water is added and stirred evenly to prepare a negative electrode slurry with a solid content of 50%. Thereafter, the negative electrode slurry is evenly coated on one side surface of a negative electrode current collector (such as copper foil) with a thickness of 6 microns. Finally, the negative electrode material layer is obtained after drying, and then further cold pressing, striping, and cutting are performed to obtain the negative electrode sheet 22.

[0078] Among them, the above-mentioned method for preparing the second lithium-containing compound Li2 and the method for preparing the positive electrode sheet 21 can be combined to ensure the uniform distribution of the lithium-replenishing particles in the second lithium-containing compound Li2 in the active material layer 212, as well as the amount of lithium ions intercalated and deintercalated from the lithium-replenishing particles, thereby ensuring the lithium-replenishing effect of the lithium-replenishing particles, thereby improving the cycle life of the energy storage device 100 during the charge and discharge stages.

[0079] Furthermore, in order to further improve the cycle life of the energy storage device 100, for the second lithium-containing compound Li2 included in the active material layer 212 on the positive electrode sheet 21, as shown in Figure 5, a connection area AA and a separation area BB can be formed between the lithium-supplementing core Li21 and the outer shell Li22 of the lithium-supplementing particles in the second lithium-containing compound Li2, and the ratio of the path length of the outer shell Li22 in the connection area AA to the total circumference of the outer shell is greater than or equal to 5% and less than or equal to 45%.

[0080] In this way, the lithium-replenishing particles in the active material layer 212 can be guaranteed to release lithium ions uniformly during the formation stage of the energy storage device 100, and can be guaranteed to release sufficient lithium ions to form a solid electrolyte interface film, thereby avoiding local lithium deposition and local purple spots on the positive electrode sheet 21 of the energy storage device 100, thereby ensuring the cycle life of the energy storage device 100; at the same time, it can avoid the situation where the lithium-replenishing particles have fewer lithium ion transmission paths due to the smaller connection area AA, resulting in poor subsequent lithium replenishment effect.

[0081] Among them, the path length of the shell Li22 in the connection area AA refers to the length of the cross-sectional profile of the shell Li22 in the connection area AA within the cross-section of the positive electrode sheet 21, and the total circumference of the shell refers to the total length of the cross-sectional profile of the shell Li22 within the cross-section of the positive electrode sheet 21; in addition, for the path length of the shell Li22 in the connection area AA, it can be for lithium-supplementing particles with separated core and shell in at least one selected observation area, measuring the path length of the shell Li22 of each lithium-supplementing particle in the connection area AA, and determining the average value of the path lengths of multiple lithium-supplementing particles in at least one observation area as the path length of the shell Li22 in the connection area AA.

[0082] Multiple connection areas AA can be formed between the lithium-replenishing core Li21 and the outer shell Li22. The path length of the outer shell Li22 in the connection areas AA can be the sum of the lengths of the cross-sectional profile of the outer shell Li22 in the connection areas AA within a cross-section of the positive electrode sheet 21. As shown in FIG5 , connection areas AA and separation areas BB are formed between the lithium-replenishing core Li21 and the outer shell Li22. The spacing L3 between the lithium-replenishing core Li21 and the outer shell Li22 in the connection areas AA is less than or equal to 5 nanometers, and the spacing L4 between the lithium-replenishing core Li21 and the outer shell Li22 in the separation areas BB is greater than 5 nanometers. Furthermore, the method for determining the path length of the outer shell Li22 in the connection areas AA and the total perimeter of the outer shell within a cross-section of the positive electrode sheet 21 can be similar to the method for determining the total outer perimeter length of the lithium-replenishing core Li21 within a cross-section of a lithium-replenishing particle described above. The difference is that the positive electrode sheet 21 is obtained by disassembling the energy storage device 100. In this case, the positive electrode sheet 21 needs to be cleaned with an electrolyte solvent to remove residual electrolyte from the positive electrode sheet 21.

[0083] It should be noted that because the lithium-replenishing core Li21 and shell Li22 of the second lithium-containing compound Li2 may form multiple alternating connection regions AA and separation regions BB, FIG5 illustratively illustrates only one connection region AA and an adjacent separation region BB. Furthermore, during formation of the energy storage device 100, only the lithium-replenishing core Li21 releases lithium ions and shrinks, while the shell Li22 does not deform in size. Therefore, the particle size of the lithium-replenishing particles does not change while the lithium-replenishing core Li21 and shell Li22 separate.

[0084] In combination with the roundness of the lithium-supplementing core Li21 described above, the ratio of the total outer contour length of the lithium-supplementing core Li21 to the circumference of the smallest circumscribed circle of the outer contour can be limited to further ensure the uniformity of lithium ion intercalation and deintercalation in the multiple lithium-supplementing particles, thereby ensuring the uniformity of lithium supplementation of the second lithium-containing compound Li2. Furthermore, in combination with the particle size of the lithium-supplementing particles described above, the uniformity of the lithium-supplementing particle size can be ensured by limiting at least one of the Dv50 particle size, Dv90 particle size, Dv10 particle size, and particle size distribution ratio of the lithium-supplementing particles, thereby ensuring the uniformity of lithium ion intercalation and deintercalation in the multiple lithium-supplementing particles, thereby ensuring the uniformity of lithium supplementation of the second lithium-containing compound Li2.

[0085] It is understood that during the formation phase of the energy storage device 100, the lithium-replenishing core Li21 included in the second lithium-containing compound Li2 releases lithium ions, thereby forming a connection region AA and a separation region BB between the lithium-replenishing core Li21 and the outer shell Li22 of the lithium-replenishing particle. The size of the connection region AA formed between the lithium-replenishing core Li21 and the outer shell Li22 is determined by the amount of lithium ions released by the lithium-replenishing core Li21 during the formation phase. Furthermore, the size of the connection region AA determines the number of lithium-ion transmission pathways formed by the lithium-replenishing core Li21, and thus determines the degree of lithium replenishment of the lithium-replenishing core Li21.

[0086] In the embodiment of the present application, within the cross-section of the positive electrode sheet 21, the separation area BB and connection area AA formed between the lithium-supplementing core Li21 and the outer shell Li22 of the lithium-supplementing particle, as well as the ratio of the path length of the outer shell Li22 in the connection area AA to the total circumference of the outer shell is greater than or equal to 5% and less than or equal to 45%, which can be formed during the formation stage of the energy storage device 100.

[0087] Specifically, the formation parameters of the energy storage device 100 during the formation stage (such as maximizing the formation voltage) can be limited to ensure that the ratio of the path length of the outer shell Li22 of the lithium-replenishing particle in the connection area AA to the total circumference of the outer shell in the active material layer 212 on the positive electrode sheet 21 is greater than or equal to 5% and less than or equal to 45%, thereby ensuring the lithium replenishment effect of the lithium-replenishing particle.

[0088] For example, the maximum formation voltage of the energy storage device 100 during the formation stage is greater than or equal to 4.0 V. For example, the maximum formation voltage of the energy storage device 100 is 4.0 V, 4.1 V, 4.2 V, 4.3 V, 4.5 V, 4.7 V, etc.

[0089] Furthermore, the total formation time of the energy storage device 100 during the formation phase can be limited to ensure that the ratio of the path length of the outer shell Li22 of the lithium-supplementing particles in the active material layer 212 on the positive electrode sheet 21 in the connection area AA to the total perimeter of the outer shell is greater than or equal to 5% and less than or equal to 45%. For example, the total formation time of the energy storage device 100 can be set to be greater than or equal to 3 hours. For example, the total formation time of the energy storage device is 3 hours, 3.2 hours, 3.6 hours, 3.8 hours, 4.0 hours, 4.2 hours, etc.

[0090] Furthermore, the minimum formation current and maximum formation current of the energy storage device 100 during multi-stage constant current charging during the formation phase can be limited to ensure that the ratio of the path length of the outer shell Li22 of the lithium-supplementing particles in the connection area AA to the total perimeter of the outer shell within the active material layer 212 on the positive electrode sheet 21 is greater than or equal to 5% and less than or equal to 45%. For example, the minimum formation current of the energy storage device 100 can be set to be greater than or equal to 0.01 times the capacity (i.e., 0.01C) and less than or equal to 0.05 times the capacity (i.e., 0.05C), and the maximum formation current of the energy storage device 100 can be set to be greater than or equal to 0.9 times the capacity (i.e., 0.9C) and less than or equal to 1 times the capacity (i.e., 1C). For example, the minimum current of the energy storage device 100 is set to 0.01C, 0.02C, 0.03C, 0.04C, 0.05C, etc.; the maximum current of the energy storage device 100 is set to 0.9C, 0.92C, 0.94C, 0.96C, 0.98C, 1C, etc.

[0091] It should be noted that the formation temperature of the energy storage device 100 during formation can be greater than or equal to 40 degrees Celsius and less than or equal to 60 degrees Celsius, so as to further ensure the release of lithium ions in the lithium-supplementing particles during formation of the energy storage device 100. For example, the formation temperature of the energy storage device 100 during formation is 40 degrees Celsius, 42 degrees Celsius, 44 degrees Celsius, 46 degrees Celsius, 50 degrees Celsius, 54 degrees Celsius, 56 degrees Celsius, 58 degrees Celsius, 60 degrees Celsius, etc. In addition, in combination with the above, the roundness, particle size and distribution of the lithium-supplementing core Li21 can also be limited, while ensuring the uniform distribution of the lithium-supplementing particles, ensuring the uniformity of lithium deposition of the lithium-supplementing particles, and thus ensuring that the ratio of the path length of the outer shell Li22 of the lithium-supplementing particle in the connection area AA to the total circumference of the outer shell is greater than or equal to 5% and less than or equal to 45%.

[0092] Next, the cycle life of the energy storage device 100 described above will be explained with reference to a specific embodiment.

[0093] Example 1: In combination with the above-described method for preparing the second lithium-containing compound Li2, lithium-supplementing particles are prepared in which the lithium-supplementing core Li21 is Li5FeO4, and the outer shell Li22 includes an Al2O3 oxide coating layer and a carbon coating layer of the second lithium-containing compound Li2 (Li5FeO4@Al2O3@C). The minimum thickness of the outer shell Li22 is greater than 30 nanometers and the average thickness is 100 nanometers. The carbon content of the second lithium-containing compound Li2 is 2%. Then, in conjunction with the above-described method for manufacturing the positive electrode sheet 21, the first lithium-containing compound Li1 (lithium iron phosphate), the second lithium-containing compound Li2, the conductive agent (conductive carbon black), and the binder (polyvinylidene fluoride) were mixed at a mass ratio of 92:3:2:3 by high-speed stirring. A solvent (N-methylpyrrolidone) was then added and stirred a second time to obtain a positive electrode slurry with a solid content of 60%. The positive electrode slurry was then coated on one surface of the current collector 211 at a single-sided coating density of 0.23 mg / mm2, dried at 110 degrees Celsius, and compacted to obtain an active material layer 212 with a compaction density of 2.5 g / cm3, thereby obtaining the positive electrode sheet 21. The negative electrode sheet 22 and separator 23 were then combined to produce the electrode assembly 20, which was then assembled with the housing 10 and end cap unit 30 to obtain the energy storage device 100.

[0094] The formation process of the energy storage device 100 is as follows: 2 minutes of storage in a 45°C constant-current oven; 5 minutes of 0.1C constant-current charging, with a voltage cap of 3.5V; 2 minutes of storage; 40 minutes of 0.3C constant-current charging, with a voltage cap of 3.5V; 2 minutes of storage; 40 minutes of 1C constant-current charging, with a voltage cap of 3.55V; 2 minutes of storage; 50 minutes of 0.1C constant-current charging, with a voltage cap of 3.8V; 2 minutes of storage; 35 minutes of 0.05C constant-current charging, with a voltage cap of 4.1V. Testing during the charge and discharge phases subsequently revealed that the energy storage device 100 exhibited a discharge capacity of 144.5 mAh / g when discharged at a rate of 0.5, with the voltage dropping from 3.65V to 2.5V. Furthermore, the cycle retention rate after 500 cycles at a rate of 0.5 was 99.5%. In addition, after disassembling the positive electrode sheet 21 of the energy storage device 100, the path length ratio of the shell Li22 of the lithium-replenishing particles in the active material layer 212 on the positive electrode sheet 21 (the ratio of the path length of the shell Li22 in the connection area AA to the total circumference of the shell) was tested to be 26.7%. The particle size distribution of the lithium-replenishing particles (Dv99-Dv10) / Dv50 was 3.6, and the powder resistance of the positive electrode sheet 21 was 0.93 ohms / cm.

[0095] Example 2: In combination with the above-described method for preparing the second lithium-containing compound Li2, lithium-supplementing particles are prepared in which the lithium-supplementing core Li21 is Li5FeO4, and the outer shell Li22 includes an Al2O3 oxide coating layer and a carbon coating layer of the second lithium-containing compound Li2 (Li5FeO4@Al2O3@C). The minimum thickness of the outer shell Li22 is greater than 30 nanometers and the average thickness is 100 nanometers. The carbon content of the second lithium-containing compound Li2 is 1.5%. Then, in conjunction with the above-described method for manufacturing the positive electrode sheet 21, the first lithium-containing compound Li1 (lithium iron phosphate), the second lithium-containing compound Li2, the conductive agent (conductive carbon black), and the binder (polyvinylidene fluoride) were mixed at a mass ratio of 92:3:2:3 by high-speed stirring. A solvent (N-methylpyrrolidone) was then added and stirred a second time to obtain a positive electrode slurry with a solid content of 60%. The positive electrode slurry was then coated on one surface of the current collector 211 at a single-sided coating density of 0.23 mg / mm2, dried at 110 degrees Celsius, and compacted to obtain an active material layer 212 with a compaction density of 2.5 g / cm3, thereby obtaining the positive electrode sheet 21. The negative electrode sheet 22 and separator 23 were then combined to produce the electrode assembly 20, which was then assembled with the housing 10 and end cap unit 30 to obtain the energy storage device 100.

[0096] The formation process of the energy storage device 100 is as follows: 2 minutes of storage in a 45°C constant-current oven; 5 minutes of charging at a 0.1C constant current, with a voltage cap of 3.5V; 2 minutes of storage; 40 minutes of charging at a 0.3C constant current, with a voltage cap of 3.5V; 2 minutes of storage; 40 minutes of charging at a 1C constant current, with a voltage cap of 3.55V; 2 minutes of storage; 50 minutes of charging at a 0.1C constant current, with a voltage cap of 3.8V; 2 minutes of storage; and 35 minutes of charging at a 0.05C constant current, with a voltage cap of 4.0V. Testing during the charge and discharge phases subsequently revealed that the energy storage device 100 exhibited a discharge capacity of 145.0 mAh / g when discharged at a rate of 0.5, with the voltage decreasing from 3.65V to 2.5V. Furthermore, the cycle retention rate after 500 cycles at a rate of 0.5 was 101.3%. In addition, after disassembling the positive electrode sheet 21 of the energy storage device 100, the path length ratio of the shell Li22 of the lithium-replenishing particles in the active material layer 212 on the positive electrode sheet 21 at the connection area AA (the ratio of the path length of the shell Li22 at the connection area AA to the total circumference of the shell) was 9.4%. The particle size distribution of the lithium-replenishing particles (Dv99-Dv10) / Dv50 was 3.6, and the powder resistance of the positive electrode sheet 21 was 0.87 ohm / cm.

[0097] Example 3: In combination with the above-described method for preparing the second lithium-containing compound Li2, lithium-supplementing particles are prepared in which the lithium-supplementing core Li21 is Li5FeO4, and the outer shell Li22 includes an Al2O3 oxide coating layer and a carbon coating layer of the second lithium-containing compound Li2 (Li5FeO4@Al2O3@C). The minimum thickness of the outer shell Li22 is greater than 30 nanometers and the average thickness is 100 nanometers. The carbon content of the second lithium-containing compound Li2 is 1.5%. Then, in conjunction with the above-described method for manufacturing the positive electrode sheet 21, the first lithium-containing compound Li1 (lithium iron phosphate), the second lithium-containing compound Li2, the conductive agent (conductive carbon black), and the binder (polyvinylidene fluoride) were mixed at a mass ratio of 92:3:2:3 by high-speed stirring. A solvent (N-methylpyrrolidone) was then added and stirred a second time to obtain a positive electrode slurry with a solid content of 60%. The positive electrode slurry was then coated on one surface of the current collector 211 at a single-sided coating density of 0.23 mg / mm2, dried at 110 degrees Celsius, and compacted to obtain an active material layer 212 with a compaction density of 2.5 g / cm3, thereby obtaining the positive electrode sheet 21. The negative electrode sheet 22 and separator 23 were then combined to produce the electrode assembly 20, which was then assembled with the housing 10 and end cap unit 30 to obtain the energy storage device 100.

[0098] The formation process of the energy storage device 100 is as follows: 2 minutes of storage in a 45°C constant-current oven; 5 minutes of charging at a 0.1C constant current, with a voltage cap of 3.5V; 2 minutes of storage; 40 minutes of charging at a 0.3C constant current, with a voltage cap of 3.5V; 2 minutes of storage; 40 minutes of charging at a 1C constant current, with a voltage cap of 3.55V; 2 minutes of storage; 50 minutes of charging at a 0.1C constant current, with a voltage cap of 3.8V; 2 minutes of storage; and 35 minutes of charging at a 0.05C constant current, with a voltage cap of 4.0V. Testing during the charge and discharge phases subsequently revealed that the energy storage device 100 exhibited a discharge capacity of 145.3 mAh / g when discharged at a 0.5x rate, with the voltage dropping from 3.65V to 2.5V. Furthermore, the cycle retention rate after 500 cycles at a 0.5x rate was 102.0%. In addition, after disassembling the positive electrode sheet 21 of the energy storage device 100, the path length ratio of the shell Li22 of the lithium-replenishing particles in the active material layer 212 on the positive electrode sheet 21 at the connection area AA (the ratio of the path length of the shell Li22 at the connection area AA to the total circumference of the shell) was tested to be 5%. The particle size distribution of the lithium-replenishing particles (Dv99-Dv10) / Dv50 was 2.2, and the powder resistance of the positive electrode sheet 21 was 0.83 ohms / cm.

[0099] Example 4: In combination with the above-described method for preparing the second lithium-containing compound Li2, lithium-supplementing particles are prepared in which the lithium-supplementing core Li21 is Li5FeO4, and the outer shell Li22 includes an Al2O3 oxide coating layer and a carbon coating layer of the second lithium-containing compound Li2 (Li5FeO4@Al2O3@C). The minimum thickness of the outer shell Li22 is greater than 30 nanometers and the average thickness is 100 nanometers. The carbon content of the second lithium-containing compound Li2 is 1.5%. Then, in conjunction with the above-described method for manufacturing the positive electrode sheet 21, the first lithium-containing compound Li1 (lithium iron phosphate), the second lithium-containing compound Li2, the conductive agent (conductive carbon black), and the binder (polyvinylidene fluoride) were mixed at a mass ratio of 92:3:2:3 by high-speed stirring. A solvent (N-methylpyrrolidone) was then added and stirred a second time to obtain a positive electrode slurry with a solid content of 60%. The positive electrode slurry was then coated on one surface of the current collector 211 at a single-sided coating density of 0.23 mg / mm2, dried at 110 degrees Celsius, and compacted to obtain an active material layer 212 with a compaction density of 2.5 g / cm3, thereby obtaining the positive electrode sheet 21. The negative electrode sheet 22 and separator 23 were then combined to produce the electrode assembly 20, which was then assembled with the housing 10 and end cap unit 30 to obtain the energy storage device 100.

[0100] The formation process of the energy storage device 100 is as follows: 2 minutes of storage in a 45°C constant-current oven; 5 minutes of charging at a 0.1C constant current, with a voltage cap of 3.5V; 2 minutes of storage; 40 minutes of charging at a 0.3C constant current, with a voltage cap of 3.5V; 2 minutes of storage; 40 minutes of charging at a 1C constant current, with a voltage cap of 3.55V; 2 minutes of storage; 50 minutes of charging at a 0.1C constant current, with a voltage cap of 3.8V; 2 minutes of storage; and 35 minutes of charging at a 0.05C constant current, with a voltage cap of 4.2V. Testing during the charge and discharge phases subsequently revealed that the energy storage device 100 exhibited a discharge capacity of 143.8 mAh / g when discharged at a 0.5x rate, with the voltage dropping from 3.65V to 2.5V. Furthermore, the cycle retention rate after 500 cycles at a 0.5x rate was 98.8%. In addition, after disassembling the positive electrode sheet 21 of the energy storage device 100, the path length ratio of the shell Li22 of the lithium-replenishing particles in the active material layer 212 on the positive electrode sheet 21 at the connection area AA (the ratio of the path length of the shell Li22 at the connection area AA to the total circumference of the shell) was tested to be 45%. The particle size distribution of the lithium-replenishing particles (Dv99-Dv10) / Dv50 was 2.2, and the powder resistance of the positive electrode sheet 21 was 0.85 ohm / cm.

[0101] Example 5: In combination with the above-described method for preparing the second lithium-containing compound Li2, lithium-supplementing particles are prepared in which the lithium-supplementing core Li21 is Li6CoO4, and the outer shell Li22 includes an Al2O3 oxide coating layer and a carbon coating layer of the second lithium-containing compound Li2 (Li6CoO4@Al2O3@C). The minimum thickness of the outer shell Li22 is greater than 30 nanometers and the average thickness is 100 nanometers. The carbon content of the second lithium-containing compound Li2 is 2%. Then, in conjunction with the above-described method for manufacturing the positive electrode sheet 21, the first lithium-containing compound Li1 (lithium iron phosphate), the second lithium-containing compound Li2, the conductive agent (conductive carbon black), and the binder (polyvinylidene fluoride) were mixed at a mass ratio of 92:3:2:3 by high-speed stirring. A solvent (N-methylpyrrolidone) was then added and stirred a second time to obtain a positive electrode slurry with a solid content of 60%. The positive electrode slurry was then coated on one surface of the current collector 211 at a single-sided coating density of 0.23 mg / mm2, dried at 110 degrees Celsius, and compacted to obtain an active material layer 212 with a compaction density of 2.5 g / cm3, thereby obtaining the positive electrode sheet 21. The negative electrode sheet 22 and separator 23 were then combined to produce the electrode assembly 20, which was then assembled with the housing 10 and end cap unit 30 to obtain the energy storage device 100.

[0102] The formation process of the energy storage device 100 is as follows: 2 minutes of storage in a 45°C constant-current oven; 5 minutes of charging at a 0.1C constant current, with a voltage cap of 3.5V; 2 minutes of storage; 40 minutes of charging at a 0.3C constant current, with a voltage cap of 3.5V; 2 minutes of storage; 40 minutes of charging at a 1C constant current, with a voltage cap of 3.55V; 2 minutes of storage; 50 minutes of charging at a 0.1C constant current, with a voltage cap of 3.8V; 2 minutes of storage; and 35 minutes of charging at a 0.05C constant current, with a voltage cap of 4.1V. Testing during the charge and discharge phases subsequently revealed that the energy storage device 100 exhibited a discharge capacity of 145.3 mAh / g when discharged at a 0.5x rate, with the voltage dropping from 3.65V to 2.5V. Furthermore, the cycle retention rate after 500 cycles at a 0.5x rate was 102.1%. In addition, after disassembling the positive electrode sheet 21 of the energy storage device 100, the path length ratio of the shell Li22 of the lithium-replenishing particles in the active material layer 212 on the positive electrode sheet 21 at the connection area AA (the ratio of the path length of the shell Li22 at the connection area AA to the total circumference of the shell) was tested to be 7%. The particle size distribution of the lithium-replenishing particles (Dv99-Dv10) / Dv50 was 2.0, and the powder resistance of the positive electrode sheet 21 was 0.87 ohms / cm.

[0103] Example 6: In combination with the above-described method for preparing the second lithium-containing compound Li2, lithium-supplementing particles are prepared in which the lithium-supplementing core Li21 is Li5FeO4, and the outer shell Li22 includes an AlF3 oxide coating layer and a carbon coating layer of the second lithium-containing compound Li2 (Li5FeO4@AlF3@C). The minimum thickness of the outer shell Li22 is greater than 30 nanometers and the average thickness is 100 nanometers. The carbon content of the second lithium-containing compound Li2 is 1.5%. Then, in conjunction with the above-described method for manufacturing the positive electrode sheet 21, the first lithium-containing compound Li1 (lithium iron phosphate), the second lithium-containing compound Li2, the conductive agent (conductive carbon black), and the binder (polyvinylidene fluoride) were mixed at a mass ratio of 92:3:2:3 by high-speed stirring. A solvent (N-methylpyrrolidone) was then added and stirred a second time to obtain a positive electrode slurry with a solid content of 60%. The positive electrode slurry was then coated on one surface of the current collector 211 at a single-sided coating density of 0.23 mg / mm2, dried at 110 degrees Celsius, and compacted to obtain an active material layer 212 with a compaction density of 2.5 g / cm3, thereby obtaining the positive electrode sheet 21. The negative electrode sheet 22 and separator 23 were then combined to produce the electrode assembly 20, which was then assembled with the housing 10 and end cap unit 30 to obtain the energy storage device 100.

[0104] The formation process of the energy storage device 100 is as follows: 2 minutes of storage in a 45°C constant-current oven; 5 minutes of charging at a 0.1C constant current, with a voltage cap of 3.5V; 2 minutes of storage; 40 minutes of charging at a 0.3C constant current, with a voltage cap of 3.5V; 2 minutes of storage; 40 minutes of charging at a 1C constant current, with a voltage cap of 3.55V; 2 minutes of storage; 50 minutes of charging at a 0.1C constant current, with a voltage cap of 3.8V; 2 minutes of storage; and 35 minutes of charging at a 0.05C constant current, with a voltage cap of 4.1V. Testing during the charge and discharge phases subsequently revealed that the energy storage device 100 exhibited a discharge capacity of 145.2 mAh / g when discharged at a rate of 0.5, with the voltage dropping from 3.65V to 2.5V. Furthermore, the cycle retention rate after 500 cycles at a rate of 0.5 was 101.8%. In addition, after disassembling the positive electrode sheet 21 of the energy storage device 100, the path length ratio of the shell Li22 of the lithium-replenishing particles in the active material layer 212 on the positive electrode sheet 21 at the connection area AA (the ratio of the path length of the shell Li22 at the connection area AA to the total circumference of the shell) was tested to be 8%. The particle size distribution of the lithium-replenishing particles (Dv99-Dv10) / Dv50 was 2.5, and the powder resistance of the positive electrode sheet 21 was 0.88 ohm / cm.

[0105] Example 7: Compared to Example 2, the formula is as follows: the first lithium-containing compound Li1 (lithium iron phosphate), the second lithium-containing compound Li2, the conductive agent (conductive carbon black), and the binder (polyvinylidene fluoride) are mixed in a mass ratio of 94:1:2:3. After formation, the energy storage device 100 was tested during charge and discharge cycles. The discharge capacity of the energy storage device 100 at a discharge rate of 0.5x, with the voltage dropping from 3.65 volts to 2.5 volts, was 143.7 mAh / g. The cycle retention rate after 500 cycles at a charge and discharge rate of 0.5x was 98.1%. In addition, after disassembling the positive electrode sheet 21 of the energy storage device 100, the path length ratio of the shell Li22 of the lithium-replenishing particles in the active material layer 212 on the positive electrode sheet 21 at the connection area AA (the ratio of the path length of the shell Li22 at the connection area AA to the total circumference of the shell) was 9.4%. The particle size distribution of the lithium-replenishing particles (Dv99-Dv10) / Dv50 was 3.6, and the powder resistance of the positive electrode sheet 21 was 0.87 ohm / cm.

[0106] Example 8: Compared to Example 2, the formula is as follows: the first lithium-containing compound Li1 (lithium iron phosphate), the second lithium-containing compound Li2, the conductive agent (conductive carbon black), and the binder (polyvinylidene fluoride) are mixed in a mass ratio of 90:5:2:3. After formation, the energy storage device 100 was tested during charge and discharge cycles. The discharge capacity of the energy storage device 100 at a discharge rate of 0.5x, with the voltage dropping from 3.65 volts to 2.5 volts, was 147.0 mAh / g. The cycle retention rate after 500 cycles at a charge and discharge rate of 0.5x was 101.5%. In addition, after disassembling the positive electrode sheet 21 of the energy storage device 100, the path length ratio of the shell Li22 of the lithium-replenishing particles in the active material layer 212 on the positive electrode sheet 21 at the connection area AA (the ratio of the path length of the shell Li22 at the connection area AA to the total circumference of the shell) was 9.4%. The particle size distribution of the lithium-replenishing particles (Dv99-Dv10) / Dv50 was 3.6, and the powder resistance of the positive electrode sheet 21 was 0.87 ohm / cm.

[0107] Comparative Example 1: In combination with the above-described method for preparing the second lithium-containing compound Li2, lithium-supplementing particles are prepared in which the lithium-supplementing core Li21 is Li5FeO4, and the outer shell Li22 includes an Al2O3 oxide coating layer and a carbon coating layer of the second lithium-containing compound Li2 (Li5FeO4@Al2O3@C). The minimum thickness of the outer shell Li22 is 25 nanometers, and the carbon content of the second lithium-containing compound Li2 is 0.4%. Then, in conjunction with the above-described method for manufacturing the positive electrode sheet 21, the first lithium-containing compound Li1 (lithium iron phosphate), the second lithium-containing compound Li2, the conductive agent (conductive carbon black), and the binder (polyvinylidene fluoride) were mixed at a mass ratio of 92:3:2:3 by high-speed stirring. A solvent (N-methylpyrrolidone) was then added and stirred a second time to obtain a positive electrode slurry with a solid content of 60%. The positive electrode slurry was then coated on one surface of the current collector 211 at a single-sided coating density of 0.23 mg / mm2, dried at 110 degrees Celsius, and compacted to obtain an active material layer 212 with a compaction density of 2.5 g / cm3, thereby obtaining the positive electrode sheet 21. The negative electrode sheet 22 and separator 23 were then combined to produce the electrode assembly 20, which was then assembled with the housing 10 and end cap unit 30 to obtain the energy storage device 100.

[0108] The energy storage device 100 was placed in a 45°C constant-temperature oven for 2 minutes, then charged at a constant current of 0.1C for 5 minutes, with a voltage cap of 3.5V. The device was then placed for 2 minutes, then charged at a constant current of 0.3C for 40 minutes, with a voltage cap of 3.5V. The device was placed for 2 minutes, then charged at a constant current of 1C for 40 minutes, with a voltage cap of 3.55V. The device was placed for 2 minutes, then charged at a constant current of 0.1C for 50 minutes, with a voltage cap of 3.8V. The device was placed for 2 minutes, then charged at a constant current of 0.1C for 35 minutes, with a voltage cap of 3.9V. Subsequently, the device was tested during the charge and discharge phases, and the discharge capacity was 143.7 mAh / g when the voltage dropped from 3.65V to 2.5V at a discharge rate of 0.5. The cycle retention rate after 500 cycles at a charge and discharge rate of 0.5 was 97.0%. In addition, after disassembling the positive electrode sheet 21 of the energy storage device 100, the path length ratio of the shell Li22 of the lithium-replenishing particles in the active material layer 212 on the positive electrode sheet 21 at the connection area AA (the ratio of the path length of the shell Li22 at the connection area AA to the total circumference of the shell) was tested to be 4%. The particle size distribution of the lithium-replenishing particles (Dv99-Dv10) / Dv50 was 3.6, and the powder resistance of the positive electrode sheet 21 was 1.01 ohms / cm.

[0109] Comparative Example 2: Combined with the preparation method of the second lithium-containing compound Li2 described above, the lithium-supplementing core Li21 of the lithium-supplementing particles is Li5FeO4, and the outer shell Li22 includes an Al2O3 oxide coating layer and a carbon coating layer of the second lithium-containing compound Li2 (Li5FeO4@Al2O3@C). The minimum thickness of the outer shell Li22 is greater than 30 nanometers and the average thickness is 220 nanometers. The carbon content of the second lithium-containing compound Li2 is 0.4%. Then, in conjunction with the above-described method for manufacturing the positive electrode sheet 21, the first lithium-containing compound Li1 (lithium iron phosphate), the second lithium-containing compound Li2, the conductive agent (conductive carbon black), and the binder (polyvinylidene fluoride) were mixed at a mass ratio of 92:3:2:3 by high-speed stirring. A solvent (N-methylpyrrolidone) was then added and stirred a second time to obtain a positive electrode slurry with a solid content of 60%. The positive electrode slurry was then coated on one surface of the current collector 211 at a single-sided coating density of 0.23 mg / mm2, dried at 110 degrees Celsius, and compacted to obtain an active material layer 212 with a compaction density of 2.5 g / cm3, thereby obtaining the positive electrode sheet 21. The negative electrode sheet 22 and separator 23 were then combined to produce the electrode assembly 20, which was then assembled with the housing 10 and end cap unit 30 to obtain the energy storage device 100.

[0110] The energy storage device 100 was placed in a 45°C constant-current oven for 2 minutes, then charged at a constant current of 0.1C for 5 minutes, with a voltage cap of 3.5V; then placed for 2 minutes; then charged at a constant current of 0.3C for 40 minutes, with a voltage cap of 3.5V; then placed for 2 minutes; then charged at a constant current of 1C for 40 minutes, with a voltage cap of 3.55V; then placed for 2 minutes; then charged at a constant current of 0.1C for 117 minutes, with a voltage cap of 3.8V. Subsequently, testing during the charge and discharge phase revealed that the energy storage device 100 exhibited a discharge capacity of 143.6 mAh / g when discharged at a rate of 0.5, with the voltage dropping from 3.65V to 2.5V. Furthermore, after 500 cycles at a rate of 0.5, the cycle retention rate was 97.3%. In addition, after disassembling the positive electrode sheet 21 of the energy storage device 100, the path length ratio of the shell Li22 of the lithium-replenishing particles in the active material layer 212 on the positive electrode sheet 21 at the connection area AA (the ratio of the path length of the shell Li22 at the connection area AA to the total circumference of the shell) was 52%. The particle size distribution of the lithium-replenishing particles (Dv99-Dv10) / Dv50 was 3.5, and the powder resistance of the positive electrode sheet 21 was 1.08 ohms / cm.

[0111] For the energy storage devices 100 respectively including the above-mentioned Examples 1-8 and Comparative Examples 1-2, the performance parameters of the energy storage devices 100 are shown in the following table.

[0112] The energy storage devices 100 of Examples 1-8 and Comparative Examples 1-2 are prepared using the same manufacturing methods and formation processes as the energy storage devices 100 of Examples 2 and 3. However, due to the different particle size distributions (Dv99-Dv10) / Dv50 of the lithium-supplementing particles, the particle size uniformity of the lithium-supplementing particles in Example 3 is superior to that of the lithium-supplementing particles in Example 2. This results in a better uniformity in lithium ion release from the lithium-supplementing particles in Example 3 than in Example 2, and consequently, the electrochemical parameters of the energy storage device 100 in Example 3 are superior to those of the energy storage device 100 in Example 2. Similarly, the energy storage devices 100 in Examples 5 and 6 use the same manufacturing methods and formation processes. However, due to the difference in the particle size distribution (Dv99-Dv10) / Dv50 of the lithium-supplementing particles, the particle size uniformity of the lithium-supplementing particles in Example 5 is superior to that of the lithium-supplementing particles in Example 6. Consequently, the uniformity of lithium ion release from the lithium-supplementing particles in Example 5 is superior to that of the lithium-supplementing particles in Example 6, which in turn leads to better electrochemical parameters for the energy storage device 100 in Example 5 than for the energy storage device 100 in Example 6. The energy storage device 100 in Example 8 ensures uniform lithium replenishment of the lithium-supplementing particles in the positive electrode sheet 21 by setting parameters such as the maximum formation voltage. However, due to the large mass proportion of the second lithium-containing compound Li2, i.e., the excess second lithium-containing compound Li2, the lithium replenishment is excessive, resulting in uniform lithium deposition. In Examples 2, 7, and 8, the energy storage device 100 is manufactured using the same method and formation process. Although the mass percentage of the second lithium-containing compound Li2 is different, this does not affect the lithium ion intercalation and deintercalation of the lithium-supplementing particles. It only results in a different total amount of lithium ion intercalation and deintercalation, and thus different electrochemical parameters. Specifically, the mass percentage of the second lithium-containing compound Li2 in Examples 8, 2, and 7 decreases successively, resulting in completely different total amounts of lithium supplementation in the energy storage devices 100 in Examples 8, 2, and 7, and thus different electrochemical parameters.

[0113] The lithium replenishment effect of each energy storage device 100 can be confirmed by whether purple spots appear on the negative electrode sheet 22 after disassembly. To confirm whether lithium deposition occurs: the energy storage device 100 is charged from the initial temperature T0 (for example, -20 degrees Celsius) at a charging rate of 0.3 to 5 until the temperature rises ΔT (greater than or equal to 5 degrees Celsius) to reach the target temperature T1; the energy storage device 100 is continued to be charged from the target temperature T1 at a charging rate of 0.5 to 5 to 80% of the capacity, and then each energy storage device that has been charged to 80% of the capacity is charged. The device 100 is disassembled to observe whether there is lithium deposition on the negative electrode sheet, including: 1. No lithium deposition: there is no lithium deposition area on the entire negative electrode sheet 22; 2. Slight lithium deposition: the maximum area of ​​a single lithium deposition area on the entire negative electrode sheet is ≤5×5 square millimeters, and the number of lithium deposition areas on the entire negative electrode sheet 22 is ≤1; 3. Moderate lithium deposition: 5×5 square millimeters < the maximum area of ​​a single lithium deposition area on the entire negative electrode sheet is ≤10×10 square millimeters, and the number of lithium deposition areas on the entire negative electrode sheet 22 is ≤1; 4. Severe lithium deposition: lithium deposition exists and the judgment conditions for slight lithium deposition and moderate lithium deposition are not met.

[0114] The present application also provides an electrical device 400, which can be an energy storage device, a vehicle, an energy storage container, or the like. As shown in FIG7 , the electrical device 400 includes the energy storage device 100 described in the above embodiment, which supplies power to the electrical device 400. Thus, in combination with the energy storage device 100 described above, the operating stability of the electrical device 400 is improved during use, thereby extending the operating time of the electrical device 400.

[0115] In the embodiments of the present application, the terms "one", "an", "the", "said" and "at least one" are used to indicate the presence of one or more elements / components / etc.; the terms "first", "second" and "third" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance; the term "plurality" refers to two or more, unless otherwise expressly defined. Terms such as "installed", "connected", "connected", and "fixed" should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; "connected" can be a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0116] In the description of the embodiments of the present application, it should be understood that the directions or positional relationships indicated by terms such as "up", "down", "left", "right", "front", and "back" are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or unit referred to must have a specific direction, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limiting the embodiments of the present application.

[0117] Throughout this specification, terms such as "one embodiment," "some embodiments," and "specific embodiments" mean that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the implementation methods of this application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0118] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may be modified and varied in various ways. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. An energy storage device (100), characterized in that include: An electrode assembly (20) includes a positive electrode sheet (21), a negative electrode sheet (22), and a separator (23) that are stacked; The positive electrode sheet (21) comprises a current collector (211) and an active material layer (212) located on the surface of the current collector (211), wherein the active material layer (212) comprises a first lithium-containing compound (Li1) and a second lithium-containing compound (Li2) in a granular form, wherein the first lithium-containing compound (Li1) is a positive electrode active material, and the second lithium-containing compound (Li2) is a lithium-supplementing particle, wherein the lithium-supplementing particle comprises a lithium-supplementing core (Li21) and a shell (Li22) covering the lithium-supplementing core (Li21); A connection area (AA) and a separation area (BB) are formed between the lithium-supplementing core (Li21) and the shell (Li22); a distance between the lithium-supplementing core (Li21) and the shell (Li22) in the connection area (AA) is less than or equal to 5 nanometers; a distance between the lithium-supplementing core (Li21) and the shell (Li22) in the separation area (BB) is greater than 5 nanometers; and within a cross-section of the positive electrode sheet (21), a ratio of a path length of the shell (Li22) of the lithium-supplementing particle in the connection area (AA) to a total perimeter of the shell is greater than or equal to 5% and less than or equal to 45%.

2. The energy storage device (100) according to claim 1, characterized in that In the cross section of the lithium-supplementing particle, the ratio of the total length of the outer contour of the lithium-supplementing core (Li21) to the circumference of the smallest circumscribed circle of the outer contour is greater than or equal to 0.125 and less than or equal to 1.

3. The energy storage device (100) according to claim 2, characterized in that In the cross section of the lithium-supplementing particle, the ratio of the total length of the outer contour of the lithium-supplementing core (Li21) to the circumference of the smallest circumscribed circle of the outer contour is greater than or equal to 0.25 and less than or equal to 0.

9.

4. The energy storage device (100) according to claim 1, characterized in that In the cut surface of the positive electrode sheet (21), the cut edge of the shell (Li22) is a continuous structure.

5. The energy storage device (100) according to claim 4, characterized in that The thickness of the outer shell (Li22) is greater than or equal to 30 nanometers and less than or equal to 200 nanometers.

6. The energy storage device (100) according to any one of claims 1 to 5, characterized in that: The median particle size of the lithium-supplementing core (Li21) is greater than or equal to 3 microns and less than or equal to 10 microns.

7. The energy storage device (100) according to claim 6, characterized in that The housing (Li22) includes M x O y coating layer and a conductive coating layer, and the M x O y The cladding layer is located in the inner layer; Wherein, M is at least one of the elements Fe, Co, Ni, Ti, Zn, Mg, Al, Mn, V, Cr, Zr, Cu, Nb, Ta, W, Zr, Y, and La, and 1≤x≤3, 1≤y≤5.

8. The energy storage device (100) according to claim 7, characterized in that The conductive coating layer is a carbon coating layer.

9. The energy storage device (100) according to claim 8, characterized in that The carbon content in the second lithium-containing compound (Li2) is greater than or equal to 0.5% by mass and less than or equal to 4% by mass.

10. The energy storage device (100) according to claim 1, characterized in that The mass proportion of the second lithium-containing compound (Li2) in the active material layer (212) is greater than or equal to 0.3% and less than or equal to 5%.

11. The energy storage device (100) according to claim 1, characterized in that The lithium supplement core (Li21) is Li 1+r M 1-p N p O 4-s B s , where 0.1 < r < 6.1, 0 ≤ p < 0.99, 0 ≤ s < 0.1, M and N are at least one of the elements Fe, Co, Ni, Ti, Zn, Mg, Al, Mn, V, Cr, Zr, Cu, Nb, Ta, W, Zr, Y, La respectively, and B is at least one of the elements S, N, F, Cl, Br.

12. An electrical device (400), characterized in that: The electrical device (400) comprises the energy storage device (100) according to any one of claims 1 to 11, and the energy storage device (100) supplies power to the electrical device (400).

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