Lithium ion secondary battery and electric device

Abstract

The invention relates to a lithium ion secondary battery and an electric device. In the width direction of the positive electrode current collector, the positive electrode film layer comprises first areas and second areas, and the first areas are arranged on the two sides of the second areas; the first region includes: a first positive electrode active material; the second region comprises a first positive electrode active material and a second positive electrode active material, and the ratio of the mass content of the first positive electrode active material in the second region to the mass content of the second positive electrode active material in the second region is (89-96): (1-8); the first positive electrode active material includes a lithium-containing transition metal oxide of a layered structure, and the second positive electrode active material includes a lithium-containing transition metal phosphate of an olivine structure. By means of the design, the total mass content of manganese in the middle area of the positive pole piece is reduced, manganese dissolution of the corresponding center area of the negative pole piece during high-temperature and high-voltage storage can be reduced, and damage to an SEI film caused by migration of dissolved Mn ions to the negative pole piece is reduced; and lithium precipitation of the negative pole piece is improved.

Description

Technical Field

[0001] The present application relates to a lithium-ion secondary battery and an electrical device. Background Art

[0002] As an emerging sustainable energy storage technology, lithium-ion batteries have the characteristics of low cost and environmental friendliness, so their application has been increasingly developed in recent years.

[0003] Therefore, higher requirements are placed on the high-temperature storage performance of lithium-ion batteries. Summary of the invention

[0004] The purpose of the present application is to provide a lithium-ion secondary battery and an electrical device.

[0005] The embodiment of the present application is implemented as follows:

[0006] In a first aspect, an embodiment of the present application provides a lithium-ion secondary battery, comprising:

[0007] Positive electrode sheet, negative electrode sheet and separator;

[0008] The positive electrode sheet includes a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector;

[0009] Along the width direction of the positive electrode current collector, the positive electrode film layer includes a first region and a second region, and the first region is arranged on both sides of the second region;

[0010] The first region includes: a first positive electrode active material;

[0011] The second region includes: a first positive electrode active material and a second positive electrode active material, wherein a ratio of a mass content of the first positive electrode active material in the second region to a mass content of the second positive electrode active material in the second region is (89-96): (1-8);

[0012] The first positive electrode active material includes a layered lithium-containing transition metal oxide, and the second positive electrode active material includes an olivine-structured lithium-containing transition metal phosphate.

[0013] In the above technical solution, along the width direction of the positive electrode current collector, the first region is arranged on both sides of the second region, which is equivalent to the second region being located in the middle region of the positive electrode plate, and the positive electrode film layer in the second region includes two positive electrode materials, namely, a layered transition metal oxide and an olivine structured lithium-containing transition metal phosphate, and within the above-mentioned mass ratio range, the content of the layered lithium-containing transition metal oxide in the middle region of the positive electrode plate is effectively reduced, thereby reducing the dissolution of transition metals such as manganese in the layered transition metal oxide in the middle region of the entire positive electrode plate, so that compared with the positive electrode film layer containing only layered transition metal oxides, the technical solution of the present application can reduce the dissolution amount of transition metal elements such as manganese in the middle region of the positive electrode plate, thereby reducing the dissolution of transition metal elements such as manganese in the middle region of the positive electrode plate, and thus the total amount of transition metal elements such as manganese that can migrate to the middle region of the corresponding negative electrode plate is also reduced, thereby reducing the damage to the SEI film of the negative electrode plate and improving the lithium precipitation of the negative electrode plate; and thus it is beneficial to improve the high temperature storage performance of the battery.

[0014] In some embodiments, a ratio of a mass content of the first positive electrode active material in the second region to a mass content of the second positive electrode active material in the second region is (89-91):(6-8).

[0015] In some embodiments, the second region is a rectangular region, and along the width direction, the width of the second region is 20%-70% of the width of the positive electrode film layer; optionally, the width of the second region is 50%-70% of the width of the positive electrode film layer.

[0016] In some embodiments, the first region is disposed on two opposite sides of the positive electrode film layer.

[0017] In some embodiments, based on the total mass of the second region, the mass content of the second positive electrode active material in the second region is 1% to 8%; alternatively, the mass content of the second positive electrode active material in the second region is 6% to 8%.

[0018] In some embodiments, based on the total mass of the second region, the mass content of the first positive electrode active material and the second positive electrode active material in the second region is 95% to 97%.

[0019] In some embodiments, based on the total mass of the first region, the mass content of the first positive electrode active material in the first region is 95% to 97%.

[0020] In some embodiments, the first cathode active material has a Dv50 of 3.3 μm to 3.8 μm.

[0021] In some embodiments, the second positive active material has a Dv50 of 1.4 μm to 1.8 μm.

[0022] In some embodiments, the layered lithium-containing transition metal oxide has a chemical formula of: Li a Ni b Co c Mn d M e O f R g , where 0.75 ≤ a ≤ 1.2, 0.3 < b < 1.0, 0 < c < 0.4, 0 < d < 1, 0 ≤ e ≤ 0.2, 1 ≤ f ≤ 2.5, 0 ≤ g ≤ 1, f + g ≤ 3, M includes one or more elements selected from Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, Sr, Sb, Y, W, Nb, and R includes one or more elements selected from N, F, S, Cl.

[0023] In some embodiments, the olivine-structured lithium-containing transition metal phosphate has a chemical formula of: Li 1+x Fe 1- y A y P 1-z R z O i , where x is any value in the range of -0.100 to 0.100, y is any value in the range of 0.001 to 0.500, z is any value in the range of 0.001 to 0.100, i is any value in the range of 3.5 to 4, A includes one or more elements selected from Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Co, Ga, Sn, Sb, Nb, and Ge, and R includes one or more elements selected from B, S, Si, and N.

[0024] In a third aspect, an electrical device provided by an embodiment of the present application includes the lithium-ion secondary battery provided by any one of the foregoing implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] To more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required for the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0026] Figure 1 is a schematic diagram of the positive electrode film layer (including the tab) of an embodiment of the present application;

[0027] Figure 2 is a schematic diagram of a battery cell of an embodiment of the present application;

[0028] Figure 3 yes Figure 1 An exploded view of a battery cell according to an embodiment of the present application is shown;

[0029] Figure 4 is a schematic diagram of a battery module according to an embodiment of the present application;

[0030] Figure 5 is a schematic diagram of a battery pack according to an embodiment of the present application;

[0031] Figure 6 yes Figure 4 An exploded view of a battery pack according to an embodiment of the present application is shown;

[0032] Figure 7 is a schematic diagram of an electrical device using a battery as a power source according to an embodiment of the present application;

[0033] Figure 8 It is a schematic diagram of the decomposition voltage test;

[0034] Fig. 9 Schematic diagram of the positive electrode slurry filtration performance test.

[0035] icon:

[0036] 110 first area; 120 second area; 130 pole ear; 1 battery pack; 2 upper box; 3 lower box; 4 battery module; 5 battery cell; 51 shell; 52 electrode assembly; 53 top cover assembly. DETAILED DESCRIPTION

[0037] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0039] In the description of the embodiments of the present application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features.

[0040] In the description of the embodiments of the present application, the orientations or positional relationships indicated by the technical terms "inside" and "outside" are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0041] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0042] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0043] In the embodiments of the present application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the heights, lengths, widths, and other dimensions of the various components in the embodiments of the present application shown in the drawings, as well as the overall heights, lengths, widths, and other dimensions of the integrated device are only exemplary descriptions and should not constitute any limitation to the present application.

[0044] At present, the problem of battery performance diving during high-temperature storage of lithium-ion batteries often occurs. After disassembling the interface, it was found that there was serious lithium deposition in the middle of the negative electrode. After a series of research and analysis, the cause was locked in that the transition metal elements (especially manganese elements) in the layered structure of lithium-containing transition metal oxides in the positive electrode were enhanced under high-temperature storage conditions. The John-Teller effect aggravated the dissolution of transition metal ions. These dissolved transition metal ions migrated to the negative electrode after dissolution and destroyed the SEI film of the negative electrode, resulting in serious lithium deposition in the middle of the negative electrode. As a result, the kinetics of the negative electrode decreased. In addition, as the battery life increases, the battery expansion force in the middle of the negative electrode increases the most, further deteriorating the kinetics of the negative electrode, resulting in the problem of battery performance diving during high-temperature storage.

[0045] Based on this, refer to Figure 1 In a first aspect, the present application provides a lithium-ion secondary battery, including: a positive electrode sheet, a negative electrode sheet, and a separator;

[0046] Along the width direction of the positive electrode current collector, the positive electrode film layer includes a first region 110 and a second region 120, and the first region 110 is arranged on both sides of the second region 120;

[0047] The first region 110 includes: a first positive electrode active material;

[0048] The second region 120 includes: a first positive electrode active material and a second positive electrode active material, wherein a ratio of a mass content of the first positive electrode active material in the second region to a mass content of the second positive electrode active material in the second region is (89-96): (1-8);

[0049] The first positive electrode active material includes a layered lithium-containing transition metal oxide, and the second positive electrode active material includes an olivine-structured lithium-containing transition metal phosphate.

[0050] In the above technical solution, along the width direction of the positive electrode current collector, the first region is arranged on both sides of the second region, which is equivalent to the second region being located in the middle region of the positive electrode plate, and the positive electrode film layer in the second region includes two positive electrode materials, namely, a layered transition metal oxide and an olivine structured lithium-containing transition metal phosphate, and within the above-mentioned mass ratio range, the content of the layered lithium-containing transition metal oxide in the middle region of the positive electrode plate is effectively reduced, thereby reducing the dissolution of transition metals such as manganese in the layered transition metal oxide in the middle region of the entire positive electrode plate, so that compared with the positive electrode film layer containing only layered transition metal oxides, the technical solution of the present application can reduce the dissolution amount of transition metal elements such as manganese in the middle region of the positive electrode plate, thereby reducing the dissolution of transition metal elements such as manganese in the middle region of the positive electrode plate, and thus the total amount of transition metal elements such as manganese that can migrate to the middle region of the corresponding negative electrode plate is also reduced, thereby reducing the damage to the SEI film of the negative electrode plate and improving the lithium precipitation of the negative electrode plate; and thus it is beneficial to improve the high temperature storage performance of the battery.

[0051] In some embodiments of the present application, in the above-mentioned lithium-ion secondary battery, during the battery charging and discharging process, active ions are embedded and extracted back and forth between the positive electrode sheet and the negative electrode sheet. The electrolyte plays the role of conducting ions between the positive electrode sheet and the negative electrode sheet. The isolation membrane is arranged between the positive electrode sheet and the negative electrode sheet, mainly playing the role of preventing the positive and negative electrodes from short-circuiting, while allowing ions to pass through.

[0052] Reference Figure 1 In the illustrated embodiment, the above-mentioned "width direction" ( Figure 1 The arrow direction Y) is the width direction of the positive electrode film layer. The direction perpendicular to the width direction is the length direction of the positive electrode film layer. Exemplarily, when forming an electrode assembly, the electrode assembly is wound along the length direction.

[0053] Further optionally, in some embodiments of the present application, the ratio of the mass content of the first positive electrode active material in the second region to the mass content of the second positive electrode active material in the second region is (89, 90, 91, 92, 93, 94, 95, 96 or a range between any two of the foregoing values): (1, 2, 3, 4, 5, 6, 7, 8 or a range between any two of the foregoing values).

[0054] Further optionally, in some embodiments of the present application, the ratio of the mass content of the first positive electrode active material in the second region to the mass content of the second positive electrode active material in the second region is (89-91):(6-8).

[0055] In the above technical solution, the ratio of the mass content of the first positive electrode active material in the second region to the mass content of the second positive electrode active material in the second region is (89-91): (6-8), which is further beneficial to improve lithium deposition in the middle of the negative electrode sheet.

[0056] Further, refer to Figure 1 , exemplarily, in the illustrated embodiment, the second region is a rectangular region, and along the first aspect of the positive electrode film layer, the width of the second region 120 is 20% to 70% of the width of the positive electrode film layer 100 .

[0057] In the above technical solution, by setting the width of the second region along the width direction of the positive electrode film layer to be 20% to 70% of the width of the positive electrode film layer, it is beneficial to improve lithium deposition in the middle of the negative electrode plate.

[0058] Illustratively, in some embodiments of the present application, along the width direction of the positive electrode film layer 100, the width of the second region 120 is 20%, 22%, 25%, 28%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70% of the width of the positive electrode film layer 100 or a range between any two of the foregoing values.

[0059] Further optionally, in some embodiments of the present application, the first region 110 is disposed on two opposite sides of the positive electrode film layer.

[0060] Further optionally, in some embodiments of the present application, the width of the second region is 50%-70% of the width of the positive electrode film layer.

[0061] In the above technical solution, the width of the second region is 50%-70% of the width of the positive electrode film layer; this is further beneficial to improving lithium deposition in the middle of the negative electrode plate.

[0062] Furthermore, in some embodiments of the present application, based on the total mass of the second region 120 , the mass content of the second positive electrode active material in the second region is 1% to 8%.

[0063] Illustratively, in some embodiments of the present application, in the second region 120, the second positive electrode active material accounts for 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8% or a range between any two of the foregoing values ​​of the total mass of the first positive electrode active material and the second positive electrode active material, as a percentage by mass.

[0064] In the above technical solution, based on the total mass of the second region 120, the mass content of the second positive electrode active material in the second region is 1% to 8%; within this range, it is further beneficial to reduce the amount of manganese dissolution in the central area of ​​the negative electrode plate, thereby protecting the SEI film on the surface of the negative electrode plate, and is beneficial to the dynamics of the negative electrode plate, thereby effectively improving lithium precipitation in the middle of the negative electrode plate.

[0065] In the above technical solution, by setting the mass content of the second positive electrode active material in the second region to be 1% to 8% based on the total mass of the second region 120, it is further beneficial to reduce the impact of expansion and extrusion in the middle of the battery cell. According to further research, when the mass content of the second positive electrode active material in the second region is 1% to 8%, the full charge rebound rate of the corresponding negative electrode plate can be reduced by about 1.0% to 4% year-on-year, and the corresponding expansion force can be reduced by 0.05MPa to 0.3MPa under the same number of cycles during the use of the battery (generally speaking, the surface pressure threshold of the battery expansion force of the ternary system is 1.1 to 1.3Mpa); this is beneficial to improve the lithium deposition problem in the middle of the anode during the use of the battery, thereby extending the service life of the battery.

[0066] Further optionally, in some embodiments of the present application, the mass content of the second positive electrode active material in the second region is 6% to 8%.

[0067] In the above technical solution, the mass content of the second positive electrode active material in the second region is 6% to 8%, which is further beneficial to improving lithium deposition in the middle of the negative electrode sheet.

[0068] Further, in some embodiments of the present application, Dv50 of the first positive electrode active material is 3.3 μm to 3.8 μm.

[0069] Illustratively, in some embodiments of the present application, the Dv50 of the first positive electrode active material is 3.3 μm, 3.35 μm, 3.4 μm, 3.45 μm, 3.5 μm, 3.55 μm, 3.6 μm, 3.65 μm, 3.7 μm, 3.75 μm, 3.8 μm or a range between any two of the foregoing values.

[0070] In the above technical solution, by setting the Dv50 of the first positive electrode active material to 3.3 μm to 3.8 μm, it is beneficial to match the particle size of the positive electrode active material in the central area of ​​the negative electrode sheet, which is beneficial to battery dynamics.

[0071] Further optionally, in some embodiments of the present application, the Dv50 of the second positive electrode active material is 1.4 μm to 1.8 μm.

[0072] Illustratively, in some embodiments of the present application, Dv50 of the second positive electrode active material is 1.4 μm, 1.45 μm, 1.5 μm, 1.55 μm, 1.6 μm, 1.65 μm, 1.7 μm, 1.75 μm, 1.8 μm or a range between any two of the foregoing values.

[0073] In the above technical solution, by setting the Dv50 of the second positive electrode active material to 1.4 μm to 1.8 μm, it is beneficial to match the particle size of the positive electrode active material in the central area of ​​the negative electrode plate, which is beneficial to battery dynamics.

[0074] The above “D V "50" has a well-known meaning in the art, which indicates the particle size corresponding to when the cumulative volume distribution percentage of the porous conductive agent reaches 50%, and can be measured by instruments and methods known in the art. For example, it can be measured by a laser particle size analyzer with reference to GB / T19077-2016. The test instrument can be a Mastersizer 3000 laser particle size analyzer produced by Malvern Instruments Ltd., UK.

[0075] Further optionally, in some embodiments of the present application, based on the total mass of the second region, the mass content of the first positive electrode active material and the second positive electrode active material in the second region is 95% to 97%.

[0076] For example, in some embodiments of the present application, the mass content of the first positive electrode active material and the second positive electrode active material in the second region is 95%, 96%, 97% or a range between any two of the foregoing values.

[0077] Further optionally, in some embodiments of the present application, based on the total mass of the first region, the mass content of the first positive electrode active material in the first region is 95% to 97%.

[0078] Illustratively, in some embodiments of the present application, the mass content of the first positive electrode active material in the first region is 95%, 96%, 97% or a range between any two of the foregoing values.

[0079] In some embodiments of the present application, the second positive electrode active material includes: lithium-containing transition metal phosphate with an olivine structure, which has a relatively stable temperature, making it difficult for the positive electrode active material particles to break during battery use. Therefore, the rebound rate of the central film region (the second region) of the positive electrode sheet is also less than that of the two side regions (the two first regions), which can also improve the problem of swelling and extrusion in the middle of the battery; furthermore, it is beneficial to improve the problem of lithium deposition in the middle of the anode during battery use. Further, the lithium-containing transition metal phosphate with an olivine structure is disposed in the second region, which reduces the CB value and the rebound rate of the positive electrode sheet, effectively solving the problem of difficult electrolyte infiltration in the middle region due to the expansion of the electrode sheet during the cycling process, thereby achieving the purpose of extending the battery life. Therefore, the rebound rate of the middle regions of the positive and negative electrode sheets can be improved, thereby improving the problem of difficult electrolyte infiltration in the central region of the lithium-ion battery due to excessive swelling force, avoiding lithium deposition in the center, and extending the service life.

[0080] Further optionally, in some embodiments of the present application, the layered lithium-containing transition metal oxide includes the chemical formula: Li a Ni b Co c Mn d M e O f R g , where 0.75 ≤ a ≤ 1.2, 0.3 < b < 1.0, 0 < c < 0.4, 0 < d < 1, 0 ≤ e ≤ 0.2, 1 ≤ f ≤ 2.5, 0 ≤ g ≤ 1, f + g ≤ 3, M includes one or more elements of Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, Sr, Sb, Y, W, Nb, and R includes one or more elements of N, F, S, Cl.

[0081] Exemplarily, the layered lithium-containing transition metal oxide can be LiNi 0.4 Co 0.2 Mn 0.4 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, and LiNi 0.7 Co 0.15 Mn 0.15 O2, etc. Li a Ni b Co c M1 d M2 e O f R gHere, a can be any one or more values ​​in the range of 0.75 to 1.2, b can be any one or more values ​​in the range of 0.3 to 1.0, c can be any one or more values ​​in the range of 0 to 0.4, d can be any one or more values ​​in the range of 0 to 1, e can be any one or more values ​​in the range of 0 to 0.2, f can be any value in the range of 1 to 2.5, and g can be any one or more values ​​in the range of 0 to 1.

[0082] Optionally, in the technical solutions of some embodiments of the present application, the lithium-containing transition metal phosphate of the olivine structure includes a chemical formula of: Li 1+x Fe 1-y A y P 1-z R z O i , wherein x is any value in the range of -0.100 to 0.100, y is any value in the range of 0.001 to 0.500, z is any value in the range of 0.001 to 0.100, i is any value in the range of 3.5 to 4, A includes one or more elements selected from the group consisting of Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Co, Ga, Sn, Sb, Nb and Ge, and R includes one or more elements selected from the group consisting of B, S, Si and N.

[0083] In the technical solutions of some embodiments of the present application, the compound Li 1+x Fe 1-y A y P 1-z R i The preparation method may include the following steps:

[0084] (1) dissolving an iron source, an element A source to be doped with the iron site, and an acid in a solvent and stirring to generate a suspension of an iron salt doped with the element A, filtering the suspension and drying the filter cake to obtain an iron salt doped with the element A;

[0085] (2) adding a lithium source, a phosphorus source, an element R source, a solvent, and the iron salt doped with element A obtained in step (1) into a reaction container, grinding and mixing to obtain a slurry;

[0086] (3) transferring the slurry obtained in step (2) to a spray drying device for spray drying and granulation to obtain granules;

[0087] (4) Sintering the particles obtained in step (3) to obtain a positive electrode active material.

[0088] In any embodiment, the iron source may be an iron-containing substance known in the art that can be used to prepare lithium iron phosphate. For example, the iron source may be selected from elemental iron, iron oxide, iron phosphate, ferrous oxalate, ferrous carbonate, or a combination thereof.

[0089] The acid is selected from one or more of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, organic acid such as oxalic acid, etc., for example, oxalic acid. The source of element R is selected from at least one of sulfate, borate, nitrate and silicate of element R. The source of element A is selected from at least one of simple substance, oxide, phosphate, oxalate, carbonate and sulfate of A.

[0090] In the technical solutions of some embodiments of the present application, the second positive electrode active material further has a carbon-containing coating layer.

[0091] In the technical solutions of some embodiments of the present application, the mass proportion of the carbon-containing coating layer in the lithium-containing transition metal phosphate including an olivine structure is 1% to 3%; illustratively, the mass proportion of the carbon-containing coating layer in the lithium-containing transition metal phosphate including an olivine structure is 1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.8%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5% or the range between any two of the foregoing values.

[0092] It should be noted that in the list of positive electrode active materials in this application, the molar content of Li is the initial state of the material, that is, the state before feeding. The positive electrode active material is used in the battery system, and the molar content of Li will change after charge and discharge cycles.

[0093] In addition, due to the different preparation processes and conditions of the materials, the molar content of the O element is usually not strictly the coefficient of the O element in the chemical formula, and there will be fluctuations, such as Li 1+x Fe 1-y A y P 1-z R z The molar content of the O element in O4 is not strictly 4.

[0094] For example, the second positive electrode active material may be LiFePO4, LiMn 0.1 Fe 0.9 PO4、LiMn 0.2 Fe 0.8 PO4、LiMn 0.3 Fe 0.7 PO4、LiMn 0.4 Fe 0.6 PO4、LiMn 0.5 Fe 0.5 PO4、LiMn 0.6 Fe 0.4PO4、LiMn 0.7 Fe 0.3 PO4、LiMn 0.8 Fe 0.2 PO4、LiMn 0.9 Fe 0.1 PO4, LiMnPO4, LiMn 0.5 Al 0.5 P 0.5 B 0.5 O4、LiMn 0.5 Mg 0.5 P 0.5 S 0.5 O4, etc.

[0095] Further optionally, in some embodiments of the present application, the positive electrode film layer may also optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylate resin.

[0096] Further optionally, in some embodiments of the present application, the conductive agent in the positive electrode film layer may include porous carbon materials and non-porous carbon materials; illustratively, the porous carbon materials include: activated carbon, etc.; the non-porous carbon materials include: at least one of acetylene black, carbon black, carbon nanotubes, graphene or carbon nanofibers.

[0097] Further optionally, in some embodiments of the present application, the amount of the conductive agent added to the positive electrode slurry is 1% to 5% by mass. Exemplarily, the amount of the conductive agent added to the positive electrode slurry is 1%, 1.1%, 1.2%, 1.5%, 1.8%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, 3.1%, 3.2%, 3.5%, 3.8%, 4%, 4.1%, 4.5%, 4.8%, 5% or the range between any two of the foregoing values.

[0098] In some embodiments of the present application, the positive electrode slurry prepared as above is coated on at least one surface of a positive electrode current collector, and after drying, cold pressing and other processes, a positive electrode sheet can be obtained.

[0099] As an example, the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.

[0100] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0101] In some embodiments, the positive electrode sheet can be prepared in the following manner: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0102] [Negative electrode]

[0103] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer formed on at least one surface of the negative electrode current collector.

[0104] In some embodiments, the negative electrode sheet can be prepared in the following manner: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0105] In some optional embodiments of the present application, the above-mentioned negative electrode active material may include: at least one of a combination of one or more of hard carbon, graphite, soft carbon, carbon fiber, silicon-based materials, tin-based materials, lithium titanate or other metals that can form alloys with lithium, optionally, hard carbon.

[0106] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, copper foil may be used. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0107] In some embodiments, the negative electrode film layer may further include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), lithium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), lithium alginate (SA), polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).

[0108] In some embodiments, the negative electrode film layer may further include a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

[0109] In some embodiments, the negative electrode film layer may also optionally include other additives, such as a thickener (eg, carboxymethyl cellulose lithium (CMC-Li)).

[0110] In other embodiments, the current collector of the negative electrode plate may generally include a current collector body and an undercoat layer, the undercoat layer may be provided on at least one side of the current collector body, the undercoat layer substantially does not contain negative electrode active materials, and may include a small amount of carbon material, but the thickness of the coating formed by the carbon material is thin and cannot play the role of negative electrode active materials. When the current collector of the negative electrode plate includes an undercoat layer, the film layer may be provided on the surface of the side of the undercoat layer away from the current collector. In this embodiment, the negative electrode plate may be a plate without a negative electrode active material layer. For a negative electrode plate without a negative electrode active material layer, when the current collector of the negative electrode plate does not contain an undercoat layer, the film layer may be provided on the surface of at least one side of the current collector; when the current collector of the negative electrode plate includes an undercoat layer, the film layer may be provided on the surface of the side of the undercoat layer away from the current collector.

[0111] In some embodiments, the film layer may further include a binder, which is used to fix the additive on the negative electrode plate. The type of the binder is not particularly limited, and those skilled in the art may flexibly select the binder according to actual needs.

[0112] [Electrolytes]

[0113] The present application has no particular restrictions on the type of the electrolyte, which can be selected according to actual needs. For example, the electrolyte can be selected from at least one of a solid electrolyte and a liquid electrolyte (i.e., an electrolyte). Battery cells using electrolytes, and some battery cells using solid electrolytes.

[0114] The electrolyte conducts ions between the positive electrode and the negative electrode.

[0115] In some embodiments, the electrolyte salt can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0116] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane sulfone, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0117] In some embodiments, the electrolyte may further include additives, such as negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.

[0118] [Isolation film]

[0119] In some embodiments, the present application has no particular limitation on the type of isolation membrane, and any known porous structure isolation membrane with good chemical stability and mechanical stability can be selected.

[0120] In some embodiments, the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The isolation membrane can be a single-layer film or a multi-layer composite film, without particular limitation. When the isolation membrane is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0121] In some embodiments of the present application, the positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly 52 through a winding process or a lamination process.

[0122] In some embodiments, the lithium-ion secondary battery may include an outer package, which may be used to encapsulate the electrode assembly and the electrolyte.

[0123] In some embodiments, the outer packaging of the lithium ion secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the lithium ion secondary battery can also be a soft package, such as a bag-type soft package. The material of the soft package can be plastic, and as the plastic, polypropylene, polybutylene terephthalate, and polybutylene succinate can be listed.

[0124] The present application has no particular limitation on the shape of the lithium-ion secondary battery, which may be cylindrical, square, or any other shape. Figure 2 This is a lithium-ion secondary battery with a square structure as an example.

[0125] In some embodiments, reference Figure 3 , the outer package may include a shell 51 and a cover plate 53. The shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the battery cell 5 can be one or more, and those skilled in the art can select according to specific actual needs.

[0126] In the above technical solution, the term "lithium-ion secondary battery" may refer to at least one of a battery cell, a battery module or a battery pack.

[0127] For example, in some embodiments, lithium-ion secondary batteries can be assembled into a battery module. The number of battery cells contained in the battery module can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

[0128] Figure 4 4 is an example of a battery module. Figure 4 In the battery module 4, the plurality of battery cells 5 may be arranged in sequence along the length direction of the battery module 4. Of course, they may also be arranged in any other manner. Further, the plurality of battery cells 5 may be fixed by fasteners.

[0129] Optionally, the battery module 4 may further include a housing having a receiving space, and the plurality of battery cells 5 are received in the receiving space.

[0130] In some embodiments, the battery modules described above may also be assembled into a battery pack. The battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery pack.

[0131] Figure 5 and Figure 6 1 is a battery pack 1 as an example. Figure 5 and Figure 6 The battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box. The battery box includes an upper box body 2 and a lower box body 3. The upper box body 2 can cover the lower box body 3 and form a closed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0132] Some embodiments of the present application provide an electrical device, which includes a lithium-ion secondary battery provided by any of the aforementioned embodiments.

[0133] The battery cell, battery module, or battery pack can be used as a power source for the electrical device, or as an energy storage unit for the electrical device. The electrical device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited thereto.

[0134] As the electrical device, a battery cell, a battery module or a battery pack can be selected according to its usage requirements.

[0135] Figure 7 The power consumption device is taken as an example. The power consumption device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. In order to meet the high power and high energy density requirements of the power consumption device for the battery, a battery pack or a battery module can be used.

[0136] As another example, the device may be a mobile phone, a tablet computer, a notebook computer, etc. The device is usually required to be light and thin, and a battery may be used as a power source.

[0137] Example

[0138] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If no specific techniques or conditions are indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0139] Example 1

[0140] A battery cell is provided, which is prepared according to the following steps:

[0141]

Positive electrode sheet preparation

[0142] 1. Preparation of the first positive electrode slurry

[0143] In terms of mass ratio, the first positive electrode active material (LiNi 0.5 Co 0.2 Mn 0.3 O2), conductive carbon black (SP), and a binder (polyvinylidene fluoride (PVDF)) are mixed in a ratio of 97:1:2 to obtain a first positive electrode material; the mixture is added into a solvent N-methylpyrrolidone (NMP) and stirred evenly to obtain a first positive electrode slurry.

[0144] 2. Preparation of the second positive electrode slurry

[0145] In terms of mass ratio, the first positive electrode active material (LiNi 0.5 Co 0.2 Mn 0.3 O2), conductive carbon black (SP), binder (polyvinylidene fluoride (PVDF)), and second positive electrode active material (LiFePO4) are mixed in the ratio of 91:1:2:6 to obtain a second positive electrode material; the mixture is added into a solvent N-methylpyrrolidone (NMP) and stirred evenly to obtain a second positive electrode slurry.

[0146] 3. Coating

[0147] Aluminum foil was used as the current collector.

[0148] Along the width direction of the positive electrode current collector, the positive electrode film layer includes a first region and a second region, and the first region is arranged on both sides of the second region; the width of the second region accounts for 50% of the width of the positive electrode film layer. The first positive electrode slurry prepared above is evenly coated on the first region of the aluminum foil; the second positive electrode slurry prepared above is evenly coated on the second region of the aluminum foil. The coating weight of the first region and the second region is the same; both are 331mg / 1540.25mm 2 After coating, slitting and die-cutting are performed. Figure 1 As shown, the positive electrode sheet is obtained. Specific parameters are shown in Table 1.

[0149]

Negative electrode sheet preparation

[0150] The negative electrode active material graphite, conductive carbon black (SP), and binder styrene-butadiene rubber (SBR) were fully stirred and mixed in a proper amount of deionized water at a mass ratio of 97.5:1:1.5 to form a uniform negative electrode slurry; the negative electrode slurry was coated on the negative electrode current collector copper foil, and the negative electrode sheets were cut.

[0151]

Electrolyte preparation

[0152] In a glove box filled with argon, ethylene carbonate (EC), diethyl carbonate (DEC) and ethyl methyl carbonate (EMC) were mixed in a mass ratio of EC:DEC:EMC=4:2:4, and then 1.0 mol / L of lithium hexafluorophosphate (LiPF6) was added thereto.

[0153]

Isolation film

[0154] The separator is a polyethylene separator.

[0155]

Battery assembly

[0156] The positive electrode sheet, separator, and negative electrode sheet are stacked and wound in order to form a battery cell, and the battery is formed through processes such as hot pressing, shelling, welding, liquid injection, and formation.

[0157] Embodiment 2-7

[0158] The difference from Example 1 is that the various performance parameters are different, see Table 1 for details, and the rest are similar to Example 1.

[0159] Comparative Example 1

[0160] The difference from Example 1 is the preparation of the positive electrode sheet. The positive electrode sheet of this comparative example is prepared as follows:

[0161] In terms of mass ratio, the first positive electrode active material (LiNi 0.5 Co 0.2 Mn 0.3 O2), conductive carbon black (SP), and a binder (polyvinylidene fluoride (PVDF)) are mixed in a ratio of 97:1:2 to obtain a positive electrode material; the mixture is added into a solvent N-methylpyrrolidone (NMP) and stirred evenly to obtain a positive electrode slurry.

[0162] Aluminum foil was used as the current collector.

[0163] The positive electrode slurry prepared above was evenly coated on the aluminum foil, and the coating weight was 331 mg / 1540.25 mm 2 After coating, slitting and die cutting are performed to obtain positive electrode sheets. Specific parameters are shown in Table 1, and the others are similar to those in Example 1.

[0164]

Performance test

[0165] Performance tests of various examples and comparative examples:

[0166] 1. The battery cells prepared in the above embodiments or comparative examples (a sensor is clamped on the battery using a fixture, and the sensor can test the expansion force) are discharged to 2.5V at a rate of 0.33C at an ambient temperature of 25°C, and then charged to 4.35V at 0.33C; this is one cycle, and the capacity is recorded as Cn1. Thereafter, the battery is discharged to a voltage value of 2.5V with 0.33Cn, and after standing for 10 minutes, it is charged to 4.35V with 0.33Cn (corresponding to the fully charged state of the battery). During the above cycle process, the maximum expansion force F1 corresponding to the cycle is read by the sensor. Then it is stored in a constant temperature box at 50°C, and the above cycle is repeated every 30 days for 810 days. The capacity of the tested battery cell is recorded as Cn x Each time the capacity is tested, the corresponding maximum battery expansion force Fn is recorded, and then a graph is drawn with the capacity retention rate or the maximum battery expansion force as the ordinate and the storage time as the abscissa.

[0167] For example, Figure 8 and Fig. 9 The capacity retention rate graph and the expansion rate force change graph of Example 1 and Comparative Example 1 are shown.

[0168] According to the figure, calculate the battery capacity retention rate at 50°C full charge state for 810 days and the expansion force change rate at 50°C for 810 days according to the following formula

[0169] 810 days 50℃ capacity retention rate = Cn 810 / Cn1.

[0170] 810 days 50℃ expansion force change rate = F 810 / F1.

[0171] 2. Mn dissolution test

[0172] Each battery cell after the above test was disassembled and the amount of Mn dissolved on the surface of the middle area of ​​the negative electrode plate was tested:

[0173] According to GB / T 17359-2012 “Quantitative Analysis by Microbeam Energy Spectrometry”, the test was carried out using a scanning electron microscope-energy dispersive spectrometer (SEM-EDS).

[0174] The disassembled negative electrode sheet was cut into 3mm*3mm negative electrode sheet samples in the first area and the second area respectively (the first area and the second area of ​​the negative electrode sheet corresponded to the first area and the second area of ​​the positive electrode sheet one by one); the samples were respectively pasted on the sample stage of SEM-EDS, so that the surface of the negative electrode film layer away from the negative electrode current collector faced upward, and it was ensured that the area to be tested on the sample stage contained the negative electrode active material layer; the sample stage carrying the negative electrode sheet was placed in the sample chamber of SEM-EDS, and vacuumed to 5*10 -5 mbar, then adjust the distance from the sample to the condenser to 8.5 mm, then turn on the high voltage, select the appropriate area to focus, adjust the appropriate contrast and brightness for surface scanning, and use INCA software to obtain the mass percentage of Mn in the negative electrode film layer; that is, the Mn dissolution amount.

[0175] The performance test results of various embodiments and comparative examples are shown in Table 2.

[0176] Table 1 Parameters of the positive electrode film layer

[0177]

[0178] Table 2 Lithium-ion battery performance

[0179]

[0180]

[0181] From the above table data, we can see that:

[0182] The manganese dissolution amount in the second region of each embodiment is lower than that in the second region of Comparative Example 1. It can be seen that the manganese dissolution amount in the second region of each embodiment is effectively reduced; especially in Embodiment 1, Embodiment 3-Embodiment 7, relative to Comparative Example 1, the manganese dissolution amount in the second region can be reduced from 0.8% to 0.15%-0.2%, and the manganese dissolution amount in the second region is greatly reduced. It can be seen that the scheme of the embodiment of the present application can effectively reduce the manganese dissolution of the negative electrode sheet of the battery, which is conducive to improving the lithium precipitation of the negative electrode sheet.

[0183] Further, it can be seen that compared with Comparative Example 1, the 8-10 day 50°C capacity retention rate of the battery in each embodiment is effectively improved, which shows that the solution of the embodiment of the present application can effectively improve the capacity retention rate of the battery.

[0184] Further, it can be seen that, compared with Comparative Example 1, the change rate of the expansion force of the battery at 50° C. over 8-10 days in each embodiment is effectively reduced, which indicates that the solution of the embodiment of the present application can effectively improve the expansion of the battery.

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

Claims

1. A lithium ion secondary battery, characterized in that: include: Positive electrode sheet, negative electrode sheet and separator; The positive electrode plate comprises a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector; Along the width direction of the positive electrode current collector, the positive electrode film layer includes a first region and a second region, and the first region is arranged on both sides of the second region; The first region includes: a first positive electrode active material; The second region includes: a first positive electrode active material and a second positive electrode active material, wherein a ratio of a mass content of the first positive electrode active material in the second region to a mass content of the second positive electrode active material in the second region is (89-96): (1-8); The first positive electrode active material includes a lithium-containing transition metal oxide with a layered structure, and the second positive electrode active material includes a lithium-containing transition metal phosphate with an olivine structure.

2. The lithium ion secondary battery according to claim 1, characterized in that: The ratio of the mass content of the first positive electrode active material in the second region to the mass content of the second positive electrode active material in the second region is (89-91):(6-8).

3. The lithium ion secondary battery according to claim 1 or 2, characterized in that: The second region is a rectangular region, and along the width direction, the width of the second region is 20%-70% of the width of the positive electrode film layer; optionally, the width of the second region is 50%-70% of the width of the positive electrode film layer.

4. The lithium ion secondary battery according to any one of claims 1 to 3, characterized in that: The first region is arranged on two opposite sides of the positive electrode film layer.

5. The lithium ion secondary battery according to any one of claims 1 to 4, characterized in that: Based on the total mass of the second region, the mass content of the second positive electrode active material in the second region is 1% to 8%; optionally, the mass content of the second positive electrode active material in the second region is 6% to 8%.

6. The lithium ion secondary battery according to any one of claims 1 to 5, characterized in that: The mass content of the first positive electrode active material and the second positive electrode active material in the second region is 95% to 97% based on the total mass of the second region.

7. The lithium ion secondary battery according to any one of claims 1 to 6, characterized in that: The mass content of the first positive electrode active material in the first region is 95% to 97% based on the total mass of the first region.

8. The lithium ion secondary battery according to any one of claims 1 to 7, characterized in that: The Dv50 of the first positive electrode active material is 3.3 μm to 3.8 μm.

9. The lithium ion secondary battery according to any one of claims 1 to 8, characterized in that: The Dv50 of the second positive electrode active material is 1.4 μm to 1.8 μm.

10. The lithium ion secondary battery according to any one of claims 1 to 9, characterized in that: The lithium-containing transition metal oxide of the layered structure includes: with the chemical formula Li a Ni b Co c Mn d M e O f R g , where 0.75 ≤ a ≤ 1.2, 0.3 < b < 1.0, 0 < c < 0.4, 0 < d < 1, 0 ≤ e ≤ 0.2, 1 ≤ f ≤ 2.5, 0 ≤ g ≤ 1, f + g ≤ 3, M includes one or more elements of Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, Sr, Sb, Y, W, Nb, and R includes one or more elements of N, F, S, Cl.

11. The lithium ion secondary battery according to any one of claims 1 to 10, characterized in that: The lithium-containing transition metal phosphate of the olivine structure comprises: 1+x Fe 1-y A y P 1-z R z O i , wherein x is any value in the range of -0.100 to 0.100, y is any value in the range of 0.001 to 0.500, z is any value in the range of 0.001 to 0.100, i is any value in the range of 3.5 to 4, A includes one or more elements selected from the group consisting of Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Co, Ga, Sn, Sb, Nb and Ge, and R includes one or more elements selected from the group consisting of B, S, Si and N.

12. An electrical device, characterized in that: The electrical device comprises the lithium-ion secondary battery according to any one of claims 1 to 11.

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