Secondary battery and electric equipment

Abstract

The embodiment of the invention provides a secondary battery and electric equipment, and the secondary battery provided by the embodiment of the invention realizes targeted supplement of active ions in different areas by arranging an active ion supplement substance with larger mass at the edge area of a positive pole piece, ensures sufficient active ions of the pole piece and uniform distribution of the active ions, and improves the efficiency of the secondary battery. The risk of battery structure looseness is reduced, so that the cycle life and the energy density of the secondary battery are remarkably improved.

Description

Technical Field

[0001] The present application relates to the technical field of battery manufacturing, and particularly to a secondary battery and an electrical device using the same. Background Art

[0002] Currently, with the continuous growth of energy demand and the pursuit of sustainable energy, secondary batteries such as lithium-ion batteries and sodium-ion batteries have received extensive attention.

[0003] However, during the first charge and discharge process of existing secondary batteries, some active ions are consumed at the negative electrode, resulting in a reduction in battery capacity. In the prior art, active ion supplement substances (such as sodium supplement agents or lithium supplement agents) are simply added to the positive and negative electrode materials of the battery or on the electrode surface to achieve the supplement of active ions. After long-term cycling of the secondary battery, the active ion supplement substances are continuously consumed, which causes a certain degree of reduction in the thickness of the electrode sheet. This easily leads to loosening of the battery structure. In addition, during the battery cycling process, the consumption of active ions is not uniform. The consumption amount in the edge region of the electrode sheet is often greater than that in the central region. According to the existing solutions, there is a drawback that active ions cannot be evenly supplemented to the electrode sheet, thus affecting the improvement of the battery cycle life. Summary of the Invention

[0004] The technical problem to be solved by the present application is to provide a secondary battery and an electrical device using the same, so as to solve the problem that the existing method of supplementing active ions easily leads to loosening of the battery structure and reduces the battery cycle life.

[0005] To solve the above problems, the present application is implemented by the following technical solutions:

[0006] The present application provides a secondary battery, which includes a battery cell assembly. The battery cell assembly includes a negative electrode sheet, a separator, and a positive electrode sheet that are sequentially stacked. The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer provided on at least one surface of the positive electrode current collector. An active ion supplement layer is provided in the positive electrode active material layer.

[0007] The positive electrode active material layer includes positive electrode active materials. The active ion supplement layer includes active ion supplement substances. The positive electrode sheet includes a central region and an edge region surrounding the central region, and the total mass of the active ion supplement substances in the edge region is greater than the total mass in the central region.

[0008] Further, in the secondary battery, grooves are provided on the surface of the positive electrode active material layer, and the active ion supplement substances are provided in the grooves.

[0009] Further, in the secondary battery, the thickness of the grooves is less than or equal to the thickness of the positive electrode active material layer.

[0010] Further, in the secondary battery, the thickness of the groove is 10% to 100% of the thickness of the positive electrode active material layer.

[0011] Further, in the secondary battery, the volume of the groove in the edge region is larger than the volume of the groove in the central region.

[0012] Further, in the secondary battery, the groove is in a strip shape, a loop shape or a block shape.

[0013] Further, in the secondary battery, the active ion supplementing substance includes a sodium ion compound, and the sodium ion compound includes at least one of NaP3, Na2S, NaN3, Na3P, NaCrO2, NaNiO2, Na2CO3, NaNO2, Na2C4O4, Na2C2O4, Na2C6O6, Na2C6H2O6, EDTA-4Na, and DTPA-5Na.

[0014] Further, in the secondary battery, the active ion supplementing substance includes a lithium ion compound, and the lithium ion compound includes at least one of Li2O, Li2O2, Li3N, Li5FeO4, Li2NiO2, Li6CoO4, Li2C2O4, and LiBOB.

[0015] Further, in the secondary battery, the ratio G between the total mass of the active ion supplementing substance in the edge region and the total mass in the central region satisfies: 1 < G ≤ 10.

[0016] The present application also provides an electrical device, which includes the above secondary battery as a power supply for the electrical device.

[0017] Compared with the prior art, the embodiments of the present application have the following advantages:

[0018] In the present application, by providing an active ion supplementing layer with a larger mass at the edge region of the positive electrode plate, targeted supplementation of active ions in different regions is achieved, ensuring sufficient active ions and uniform distribution of active ions in the plate, reducing the risk of causing loosening of the battery structure, and improving the cycle life and energy density of the secondary battery.

[0019] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a first schematic structural view of a positive electrode plate in an embodiment of the present application;

[0021] Figure 2 isFigure 1 Cross-sectional view in the A direction of;

[0022] Figure 3 It is the second structural schematic diagram of the positive electrode plate in the embodiment of the present application;

[0023] Figure 4 is Figure 3 Cross-sectional view in the B direction of;

[0024] Figure 5 It is the third structural schematic diagram of the positive electrode plate in the embodiment of the present application;

[0025] Figure 6 is Figure 5 Cross-sectional view in the C direction of.

[0026] Explanation of reference numerals:

[0027] 10 - Positive electrode plate, 11 - Positive current collector, 12 - Positive active material layer, 101 - Central region, 102 - Edge region, 13 - Active ion replenishing layer, 14 - Groove. Detailed implementation manners

[0028] To make the above objects, features, and advantages of the present application more obvious and understandable, the present application will be further described in detail below with reference to the accompanying drawings and specific implementation manners.

[0029] In the embodiment of the present application, to solve the above problems, a secondary battery is provided. The secondary battery includes a cell assembly, and the cell assembly includes a negative electrode plate, a separator, and a positive electrode plate that are sequentially stacked. As Figures 1 to 6 shown, the positive electrode plate 10 includes a positive current collector 11 and a positive active material layer 12 provided on at least one surface of the positive current collector 11. An active ion replenishing layer 13 is provided in the positive active material layer 12; the positive active material layer 12 includes positive active materials, and the active ion replenishing layer includes active ion replenishing materials. The positive electrode plate 10 includes a central region 101 and an edge region 102 surrounding the central region 101, and the total mass of the active ion replenishing materials in the edge region is greater than that in the central region.

[0030] Among them, considering that due to the edge effect, at the edge of the electrode plate, the current density is large, polarization is likely to occur, and the electrolyte contacts the edge of the electrode plate more fully and has higher reaction activity, resulting in greater consumption of active ions in the edge region and prone to side reactions, leading to relatively fast capacity decay; while in the present application, by providing an active ion replenishing layer with a larger mass at the edge region of the positive electrode plate, that is, replenishing more active ions to the region where the active ions are consumed more, targeted replenishment of active ions in different regions is achieved, ensuring uniform distribution of the replenishment of active ions in the electrode plate, reducing the risk of causing loosening of the battery structure, and improving the cycle life and energy density of the secondary battery.

[0031] Among them, the area ratio of the central region to the edge region is (1:1) to (2:1). For example, it can be one of 1:1, 1.5:1, 2:1 or the range value of any two of them, which can realize the targeted replenishment of the active ions in the edge region where the active ions are consumed relatively fast, and ensure that the active ions in the electrode sheet are sufficient and the distribution of the active ions is uniform. In this application, the central region of the positive electrode sheet refers to the region that occupies a certain area in the positive electrode active material layer, and this region is located at the geometric center position of each layer of the positive electrode active material layer. The edge region refers to the region that surrounds the central region and occupies a certain area in the positive electrode active material layer. Reference can be made to the Figures 1 to 6 reference numerals 101 and 102 in the attached drawings of the specification.

[0032] Optionally, the ratio G between the total mass of the active ion replenishing substance in the edge region and the total mass in the central region satisfies: 1 < G ≤ 10, which can effectively balance the difference in active ion consumption between the edge region and the central region. Optionally, in some embodiments, the ratio G of the total mass of the active ion replenishing substance in the edge region to the total mass in the central region can be one of 1.1, 2, 3, 5, 8, 10 or the range value of any two of them.

[0033] Optionally, in one embodiment, as Figure 2 , 4 , as shown in 6, a groove 14 is provided on the surface of the above-mentioned positive electrode active material layer 12, and the active ion replenishing substance is arranged in the groove 14, that is, the space of the groove is used to accommodate the active ion replenishing substance. During the battery cycling process, even if the active ion replenishing substance is consumed with the battery cycling, since the active ion replenishing substance is distributed in the groove, the thickness of the positive electrode sheet will not change, avoiding the loosening of the battery structure.

[0034] Optionally, the active ion replenishing substance can fill the groove, which can not only arrange more active ion replenishing substances in a smaller space, but also ensure the overall structural strength of the battery. The active ion replenishing substance can also not fill the groove, so as to ensure better wetting performance of the electrode sheet.

[0035] Optionally, in one embodiment, the thickness of the above-mentioned groove is less than or equal to the thickness of the positive electrode active material layer, that is, the active ion replenishing layer can be partially embedded in the positive electrode active material layer or penetrate through the positive electrode active material layer, which can not only realize the targeted replenishment of active ions in different regions, but also effectively ensure the flatness of the surface of the electrode sheet, facilitating close contact with the separator.

[0036] Optionally, in one embodiment, the thickness of the groove is 10% to 100% of the thickness of the positive electrode active material layer, which can stably arrange the active ion supplement substance on the positive electrode plate on the premise of facilitating the release of active ions and ensuring the effect of active ion supplementation. For example, the thickness of the groove can be one of 10%, 15%, 20%, 50%, 80%, 100% of the thickness of the positive electrode active material layer or the range value of any two of them.

[0037] Optionally, in a specific embodiment, the thickness of the groove in the edge region is 50 to 100% of the thickness of the positive electrode active material layer, and the thickness of the groove in the central region is 10 to 50% of the thickness of the positive electrode active material layer. Since the consumption rate of active ions in the edge region is higher than that in the central region, this setting can not only balance the active ion concentration in the edge and central regions, but also facilitate the release of active ions and ensure the effect of active ion supplementation; for example, the thickness of the groove in the edge region is one of 50%, 52%, 55%, 60%, 70%, 80%, 90%, 100% of the thickness of the positive electrode active material layer or the range value of any two of them, and the thickness of the groove in the central region is one of 10%, 12%, 15%, 20%, 30%, 40%, 50% of the thickness of the positive electrode active material layer or the range value of any two of them.

[0038] Optionally, in one embodiment, the volume of the groove in the above-mentioned edge region is greater than or equal to the volume of the groove in the central region, which can make targeted supplementation according to the consumption degree of active ions. Among them, since the active ion supplement substances distributed in the grooves in the edge region and the central region are the same, setting the volume of the groove in the edge region to be greater than or equal to the volume of the groove in the central region can make the total mass of the active ion supplement layer formed in the groove in the edge region greater than the total mass of the active ion supplement layer formed in the groove in the central region.

[0039] In the embodiments of the present application, the size adjustment of the volume can be achieved by adjusting the size of the length, width and depth, that is, setting the length of the groove in the edge region to be greater than or equal to the length of the groove in the central region, the width of the groove in the edge region to be greater than or equal to the length of the groove in the central region, and the thickness of the active ion supplement layer in the edge region to be greater than or equal to the thickness of the active ion supplement layer in the central region, so that the volume of the groove in the edge region is greater than or equal to the volume of the groove in the central region.

[0040] In the embodiments of the present application, the above-mentioned groove can be strip-shaped (as shown in Figure 1 ), loop-shaped (as shown in Figure 3 ), or block-shaped (as shown in Figure 5 ), where the block shape can be one of a cube, a rectangular block or a circular block.

[0041] Optionally, in a specific embodiment, the above-mentioned groove is strip-shaped or loop-shaped, 2 to 10 grooves are provided, and the area of a single groove accounts for 0.1 to 6% of the total area of the positive electrode plate. By setting the area of a single strip-shaped or loop-shaped groove according to the area of the positive electrode plate and dispersing it on the positive electrode active material layer, targeted supplementation of active ions in different regions can be further achieved, ensuring sufficient active ions in the electrode plate and uniform distribution of active ions.

[0042] Optionally, in a specific embodiment, the above-mentioned groove is block-shaped, 4 to 30 grooves are provided, and the area of a single groove accounts for 0.1 to 6% of the total area of the positive electrode plate. By setting the area of a single block-shaped groove according to the area of the positive electrode plate and dispersing it on the positive electrode active material layer, targeted supplementation of active ions in different regions can be further achieved, ensuring sufficient active ions in the electrode plate and uniform distribution of active ions.

[0043] Optionally, in an embodiment, the above-mentioned secondary battery can be a sodium-ion battery, and the positive electrode active material is a sodium-containing positive electrode active material. Among them, the above-mentioned active ion supplementing substance is a sodium supplementing agent. In this embodiment, by setting a sodium supplementing agent with a larger mass at the edge region of the positive electrode plate of the sodium-ion battery, targeted supplementation of sodium ions in different regions is achieved, ensuring sufficient sodium ions in the electrode plate and uniform distribution of active ions, reducing the risk of causing loosening of the battery structure, and thus significantly improving the cycle life and energy density of the secondary battery.

[0044] Optionally, in a specific embodiment, the above-mentioned active ion supplementing substance includes sodium ion compounds, and the sodium ion compounds include at least one of NaP3, Na2S, NaN3, Na3P, NaCrO2, NaNiO2, Na2CO3, NaNO2, Na2C4O4, Na2C2O4, Na2C6O6, Na2C6H2O6, EDTA-4Na, DTPA-5Na.

[0045] Optionally, in a specific embodiment, the above-mentioned sodium-containing positive electrode active material includes at least one of sodium ion transition metal oxides, sodium ion transition metal phosphates and variants, sodium ion transition metal sulfates, and Prussian blue compounds.

[0046] Optionally, in a specific embodiment, the above-mentioned sodium-containing positive electrode active material contains one or more of NaCoO2, NaMnO2, NaNi 0.33 Fe 0.33 Mn 0.33 O2, NaFePO4, NaCoPO4, Na3V2(PO4)3.

[0047] Optionally, in another embodiment, the secondary battery may be a lithium-ion battery or a sodium-ion battery, the positive electrode active material is a lithium-containing positive electrode active material, and the active ion supplement material is a lithium supplement agent. In this embodiment, by arranging a lithium supplement agent with a larger mass at the edge region of the positive electrode plate of the lithium-ion battery, targeted supplementation of lithium ions in different regions is achieved, ensuring sufficient lithium ions and uniform distribution of active ions in the electrode plate, reducing the risk of loosening of the battery structure, and thus significantly improving the cycle life and energy density of the secondary battery.

[0048] Optionally, in a specific embodiment, the active ion supplement material includes a lithium ion compound, and the lithium ion compound includes at least one of Li2O, Li2O2, Li3N, Li5FeO4, Li2NiO2, Li6CoO4, Li2C2O4, and LiBOB.

[0049] Optionally, in a specific embodiment, the lithium-containing positive electrode active material includes a lithium ion transition metal oxide. The lithium ion transition metal oxide includes at least one of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, and nickel cobalt manganese ternary compounds. The nickel cobalt manganese ternary compound may specifically be, for example, Li(Ni 0.8 Mn 0.1 Co 0.1 )O2, Li(Ni 1 / 3 Mn 1 / 3 Co 1 / 3 )O2, Li(Ni 0.5 Mn 0.2 Co 0.3 )O2, Li(Ni 0.6 Mn 0.2 Co 0.2 )O2, etc.

[0050] Optionally, in an embodiment, the positive electrode plate further includes a first binder, a second binder, a first conductive agent, and a second conductive agent. The first binder and the second binder may each include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, and tetrafluoroethylene-hexafluoropropylene copolymer. The first conductive agent and the second conductive agent may each be acetylene black, carbon fiber, carbon nanotube, carbon black, graphene, etc.

[0051] In some embodiments, the positive electrode sheet is prepared as follows: The components for preparing the positive electrode sheet, such as the above-mentioned positive electrode active material, the first binder, and any other components, are dispersed in a solvent such as N-methylpyrrolidone to form a positive electrode slurry; the above-mentioned active ion supplement material, the second binder, and the second conductive agent are dispersed in a solvent such as N-methylpyrrolidone to form an active ion supplement slurry; the positive electrode slurry and the active ion supplement slurry are simultaneously and uniformly coated on both sides of a positive electrode current collector such as aluminum foil; after processes such as baking, rolling, and cutting, the positive electrode sheet can be obtained.

[0052] The battery cell assembly provided by the present application is formed by winding a positive electrode sheet, a negative electrode sheet, and a separator after laminating them.

[0053] Among them, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer provided on the negative electrode current collector. The above-mentioned negative electrode active material layer can use a negative electrode active material for a battery, such as selected from a metal negative electrode material or a non-metal negative electrode material; when the above-mentioned secondary battery is a sodium ion secondary battery, the above-mentioned metal negative electrode material is preferably a metal foil or alloy compound such as metallic sodium, sodium alloy, tin, antimony, etc.; the non-metal negative electrode material is preferably any one or at least two combinations of hard carbon, soft carbon, graphite, and silicon suboxide.

[0054] In some embodiments, the negative electrode sheet further includes a third conductive agent and a third binder; optionally, the above-mentioned conductive agent includes one or more of conductive carbon black, acetylene black, carbon nanotubes, and graphene, and the above-mentioned binder includes a carboxymethyl cellulose-based binder and a resin-based binder.

[0055] Optionally, in one embodiment, the carboxymethyl cellulose-based binder includes one or more of sodium carboxymethyl cellulose and lithium carboxymethyl cellulose; and / or the resin-based binder includes one or more of styrene rubber, polyacrylic acid, and polyacrylonitrile.

[0056] In some embodiments, the negative electrode sheet is prepared as follows: The components for preparing the negative electrode sheet, such as the above-mentioned negative electrode active material, the second binder, and the second conductive agent, are dispersed in a solvent such as deionized water to form a negative electrode slurry; the negative electrode slurry is coated on both sides of a negative electrode current collector such as copper foil; after processes such as baking, rolling, and cutting, the negative electrode sheet can be obtained.

[0057] In practical applications, the negative electrode sheet, the separator, and the positive electrode sheet are stacked in sequence and wound to obtain a battery cell assembly, the battery cell assembly is encapsulated to obtain a bare battery cell, and the bare battery cell is baked and then filled with electrolyte, formed, secondarily encapsulated, and sorted to obtain the above-mentioned secondary battery.

[0058] The present application also proposes an electrical device, which includes the above-mentioned secondary battery, and the secondary battery is used as the power supply of the electrical device.

[0059] For the above embodiments of the electrical equipment, it includes the above secondary battery and can achieve the same technical effects. To avoid repetition, it will not be elaborated here. For relevant parts, refer to the partial description of the secondary battery embodiments.

[0060] To make the invention purpose, technical solution and beneficial effects of this application clearer, the following further describes this application in combination with embodiments. It should be understood that these embodiments are only used to illustrate this application and not to limit the scope of this application.

[0061] The following details this application through embodiments.

[0062] Testing method

[0063] (1) Capacity retention rate test:

[0064] At 25 °C, charge and discharge the battery at 1C / 1C within the voltage range of 2.5 - 4.2V until the capacity of the battery cycles to 2000 times and then stop the test, and calculate the capacity retention rate of the battery after 2000 cycles.

[0065] (2) Energy density test:

[0066] Connect the battery to the test channel in the test cabinet, charge it to 4.2V at a rate of 0.05C, and then discharge it to 2.5V at a rate of 0.33C. The energy during the discharge process is E2, and the mass of the battery cell is m, then the energy density = E2 / m.

[0067] Example 1

[0068] (1) Preparation of the positive electrode plate

[0069] a. Preparation of the active ion supplementary slurry

[0070] Mix the active ion supplementary substance Na2C2O4, the binder polyvinylidene fluoride (PVDF), and the conductive agent acetylene black according to a mass ratio of 80:10:10, add the solvent N-methylpyrrolidone (NMP) accounting for 40% of the total mass of the mixed substances, and make the slurry uniformly mixed under the action of a vacuum mixer to obtain the active ion supplementary slurry;

[0071] b. Preparation of the positive electrode active slurry

[0072] Mix the positive electrode active substance Na(Ni 0.33 Fe 0.33 Mn 0.33)O2, binder polyvinylidene fluoride (PVDF), and conductive agent acetylene black are mixed in a mass ratio of 96:2:2. Solvent N-methylpyrrolidone (NMP) equal to 40% of the total mass of the mixed substances is added, and the slurry is uniformly mixed under the action of a vacuum mixer to obtain an active ion supplement slurry;

[0073] c. The positive electrode active slurry is evenly coated on the positive electrode current collector aluminum foil through a coater by a pump at the same time. The coating width of the electrode is 20 cm. The coated electrode is transferred to an oven for drying, and then cold-pressed and slit to obtain a positive electrode. The positive electrode is divided into a central area and an edge area in a 1:1 area ratio, and three strip-shaped grooves with equal lengths are arranged in parallel at intervals on the surface of the positive electrode active material layer in the distribution pattern of the edge area, central area, and edge area. Among them, the widths of the grooves are 0.2 cm, 0.1 cm, and 0.2 cm respectively, and the depth of the grooves is equal to the thickness of the positive electrode active material layer. Then, the active ion supplement slurry is pressed into the above grooves through a coater and completely fills the grooves to form an active ion supplement layer.

[0074] (3) Preparation of the negative electrode

[0075] The negative electrode active material hard carbon, conductive agent acetylene black (Super P), and binder sodium carboxymethyl cellulose (CMC) are mixed evenly in a mass ratio of 96:2:2. Deionized water equal to 40% of the total mass of the mixed substances is added, and uniformly dispersed to make a uniform black slurry. After the mixed slurry is coated on both sides of the copper foil, it is baked, rolled, and sliced to obtain a negative electrode.

[0076] (4) Preparation of the electrolyte

[0077] Ethylene carbonate (EC) and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1. Then, 1 mol / L of NaPF6 is dissolved in the mixed organic solvent and mixed evenly to prepare an electrolyte.

[0078] (5) Preparation of the secondary battery

[0079] The positive electrode, separator (12-μm thick polypropylene separator), and negative electrode are stacked in sequence, and then wound into a bare battery core and installed in an aluminum shell. After processes such as top-side sealing, liquid injection, formation, and sorting, a sodium-ion battery with a sodium supplement sheet is obtained.

[0080] Examples 2 to 4

[0081] The difference from Example 1 is only that in the preparation process of the active ion supplement slurry, the types of active ion supplement substances are adjusted.

[0082] Examples 5 to 8

[0083] The difference from Example 1 is only that, during the preparation of the positive electrode sheet, the groove width in the central region is adjusted to 0.15 cm, the groove widths in the edge regions are adjusted to 0.1 cm respectively and the groove width in the central region is 0.05 cm, the groove width in the central region is adjusted to 0.35 cm, and the groove widths in the edge regions are adjusted to 0.25 cm respectively and the groove width in the central region is 0.05 cm.

[0084] Examples 9 - 10

[0085] The difference from Example 1 is only that, during the preparation of the positive electrode sheet, the thicknesses of the grooves in the edge region and the central region are adjusted to adjust the thickness of the active ion supply layer.

[0086] Example 11

[0087] The difference from Example 1 is only that, during the preparation of the positive electrode sheet, two loop-shaped grooves are arranged at intervals by laser etching on the surface of the positive electrode active material layer from the edge region to the central region, and the groove widths are 0.2 cm and 0.1 cm respectively.

[0088] Example 12

[0089] The difference from Example 1 is only that, during the preparation of the positive electrode sheet, cube-shaped grooves are arranged at intervals by laser etching in the edge region and the central region of the positive electrode active material layer respectively, the numbers of the grooves are 10 and 2 respectively, and the length and width of the grooves are both 0.1 cm.

[0090] Example 13

[0091] The difference from Example 12 is only that, during the preparation of the positive electrode sheet, the block-shaped grooves are adjusted to circular grooves with a radius of 0.1 cm.

[0092] Examples 14 - 15

[0093] The difference from Example 1 is only that, during the preparation of the positive electrode sheet, the active ion supply substances are adjusted to Li2O and Li2C2O4 respectively, and at the same time the positive electrode active material is adjusted to lithium ternary material Li(Ni 1 / 3 Mn 1 / 3 Co 1 / 3 )O2; during the preparation of the electrolyte, the salt is adjusted to LiPF6.

[0094] Comparative Example 1

[0095] The difference between Comparative Example 1 and Example 1 is that, during the preparation of the positive electrode sheet, the groove width in the central region is adjusted to 0.4 cm.

[0096] Comparative Example 2

[0097] The difference between Comparative Example 2 and Example 14 is that during the preparation of the positive electrode sheet, the groove width in the central region is adjusted to 0.4 cm.

[0098] The process parameters and test data of each example and comparative example are shown in Table 1.

[0099] Table 1

[0100]

[0101]

[0102] From the experimental results of Examples 1 to 13 and Comparative Example 1, and Examples 14 to 15 and Comparative Example 2, it can be seen that in the embodiments of the present application, by providing an active ion replenishment layer with a greater mass at the edge region of the positive electrode sheet, targeted replenishment of active ions in different regions is achieved, ensuring sufficient active ions and uniform distribution of active ions in the electrode sheet, reducing the risk of loosening of the battery structure, and thus significantly improving the cycle life and energy density of the secondary battery.

[0103] Although the preferred embodiments of the embodiments of the present application have been described, those skilled in the art can make additional changes and modifications once they know the basic creative concept. Therefore, the claims are intended to be construed to include the preferred embodiments and all changes and modifications falling within the scope of the embodiments of the present application.

[0104] The above provides a detailed introduction to a secondary battery and an electrical device provided by the present application. Specific examples are used in this article to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application; at the same time, for those of ordinary skill in the art, according to the idea of the present application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present application.

Claims

1. A secondary battery, characterized in that: The invention comprises a battery cell assembly, wherein the battery cell assembly comprises a negative electrode sheet, a separator and a positive electrode sheet which are stacked in sequence, wherein the positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer which is arranged on at least one side of the positive electrode current collector, wherein the positive electrode active material layer is provided with an active ion supplement layer; The positive electrode active material layer contains positive electrode active material, the active ion supplement layer contains active ion supplement material, the positive electrode plate includes a central area and an edge area surrounding the central area, and the total mass of the active ion supplement material in the edge area is greater than the total mass of the central area.

2. The secondary battery according to claim 1, characterized in that: The surface of the positive electrode active material layer is provided with a groove, and the active ion supplement material is arranged in the groove.

3. The secondary battery according to claim 2, characterized in that: The thickness of the groove is less than or equal to the thickness of the positive electrode active material layer.

4. The secondary battery according to claim 3, characterized in that: The thickness of the groove is 10% to 100% of the thickness of the positive electrode active material layer.

5. The secondary battery according to any one of claims 2 to 4, characterized in that: The volume of the groove in the edge region is greater than the volume of the groove in the central region.

6. The secondary battery according to claim 2, characterized in that: The groove is in the shape of a strip, a circle or a block.

7. The secondary battery according to claim 1, characterized in that: The active ion supplement material includes a sodium ion compound, and the sodium ion compound includes at least one of NaP3, Na2S, NaN3, Na3P, NaCrO2, NaNiO2, Na2CO3, NaNO2, Na2C4O4, Na2C2O4, Na2C6O6, Na2C6H2O6, EDTA-4Na, and DTPA-5Na.

8. The secondary battery according to claim 1, characterized in that: The active ion supplement material includes a lithium ion compound, and the lithium ion compound includes at least one of Li2O, Li2O2, Li3N, Li5FeO4, Li2NiO2, Li6CoO4, Li2C2O4, and LiBOB.

9. The secondary battery according to claim 1, characterized in that: The ratio G of the total mass of the active ion supplement material in the edge region to the total mass in the central region satisfies: 1<G≤10.

10. An electrical device, characterized in that: It comprises the secondary battery according to any one of claims 1 to 9, wherein the secondary battery is used as a power supply for the electrical equipment.

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