Positive electrode plate and battery

Abstract

To provide a battery having high energy density and having more stable cycle performance.SOLUTION: In one example, a positive electrode plate includes a positive electrode current collector, and a positive electrode active material layer provided on one side or both sides of the positive electrode current collector. The positive electrode active material layer includes a first active material layer and a second active material layer. The first active material layer is positioned in an intermediate region in a longitudinal direction on a surface of the positive electrode current collector. The second active material layer is positioned on both side edge parts in the longitudinal direction on the surface of the positive electrode current collector or the second active material layer is positioned at a periphery of a surface of the positive electrode current collector. The first active material layer includes a first active material, and the second active material layer includes a second active material. The gram capacity of the first active material is higher than that of the second active material. The positive electrode plate according to the present invention can improve the lithium precipitation problem in a negative electrode plate edge part and a battery including the positive electrode plate has higher energy density and more stable cycle performance.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to the field of battery technology, and more particularly to positive plates and batteries. [Background technology]

[0002] In the 5G era, polymer lithium-ion batteries are becoming increasingly important. As the need for battery life in new electronic devices increases, lithium-ion battery manufacturers must constantly strive to improve the energy density of lithium batteries.

[0003] Currently, material development in various areas is reaching its limits, and development costs are becoming increasingly high. In lithium-ion batteries, further increasing the areal density of the electrode plates is an effective way to improve energy density, is least dependent on material technology, and is a versatile method applicable to various product series. However, increasing the areal density of the electrode plates is likely to lead to lithium deposition problems at the edges of the negative electrode plates, which will ultimately lead to reduced battery cell performance.

[0004] Therefore, it is very important to invent a battery that can improve lithium deposition at the edge of the negative electrode and has a high energy density and more stable cycle performance. Summary of the Invention [Problem to be solved by the invention]

[0005] To solve the above-mentioned problems in the prior art, the present invention provides a positive plate and a battery including the positive plate. In the battery according to the present invention, the active materials in the middle and edge regions of the positive plate can achieve different capacities at the same voltage, and by working together with the negative plate, the problem of lithium deposition at the edge of the negative electrode can be alleviated. A battery including the positive plate of the present invention can alleviate the problem of lithium deposition in the negative plate at a high areal density, while also achieving higher energy density and better cycle performance.

[0006] During battery use, the potential at the edge of the negative plate is lower than that at the middle, so when the surface density is high, lithium deposition problems are likely to occur at the edge of the negative plate, which reduces the cycle stability of the battery. [Means for solving the problem]

[0007] The inventors of the present invention have discovered that by optimizing the positive electrode plate, the lithium deposition problem on the negative electrode plate can be improved, and the energy density and cycle stability of the battery can be improved.

[0008] As a result of further intensive research, the inventors of the present invention have found that in order to optimize the positive electrode plate, the capacity exerted by the middle region and the edge region of the positive electrode plate can be made different, thereby improving the lithium deposition problem in the negative electrode plate and improving the cycle performance of the battery.

[0009] To achieve the above object, a first aspect of the present invention discloses a positive electrode plate comprising a positive electrode current collector and a positive electrode active material layer provided on one or both sides of the positive electrode current collector, the positive electrode active material layer comprising a first active material layer and a second active material layer, the first active material layer being located in a longitudinally intermediate region of the surface of the positive electrode current collector, and the second active material layer being located on both longitudinal edge portions of the surface of the positive electrode current collector, or the second active material layer being located on the periphery of the surface of the positive electrode current collector.

[0010] Here, the first active material layer includes a first active material, the second active material layer includes a second active material, and the gram capacity of the first active material is higher than the gram capacity of the second active material.

[0011] A second aspect of the present invention discloses a battery, the positive electrode plate of which is the positive electrode plate according to the first aspect of the present invention.

[0012] In one example, the battery includes a negative electrode plate, the positive electrode plate includes a positive electrode current collector and a positive electrode active material layer provided on one or both sides of the positive electrode current collector, the positive electrode active material layer including a first active material layer and a second active material layer, the first active material layer being located in a central region in the longitudinal direction of the surface of the positive electrode current collector, and the second active material layer being located on both edge portions in the longitudinal direction of the surface of the positive electrode current collector, or the second active material layer being located on the peripheral edge of the surface of the positive electrode current collector, wherein the first active material layer includes a first active material and the second active material layer includes a second active material. The battery has a first area and a second area, the first area is a region including the first active material layer, and the CB value of the first area is CB1 = (area density of negative electrode plate x gram capacity of negative electrode active material x content of negative electrode active material) / (area density of positive electrode plate x gram capacity of first active material in first area x content of first active material in first area), the second area is a region including the second active material layer, and the CB value of the second area is CB2 = (area density of negative electrode plate x gram capacity of negative electrode active material x content of negative electrode active material) / (area density of positive electrode plate x gram capacity of second active material in second area x content of second active material in second area), and CB1 <CB2である。

[0013] In one example, 0 <CB2-CB1≦0.15である。 [Effects of the Invention]

[0014] By using the above technical means, the present invention has at least the following advantages over the prior art. (1) The middle and edge regions of the positive electrode plate of the present invention have different capacities, and the middle and edge regions have different dynamics. (2) The distribution of the active material is different between the middle region and the edge region of the positive electrode plate of the present invention. (3) The battery of the present invention has a high energy density. (4) The battery of the present invention can improve the problem of lithium deposition on the negative electrode plate. (5) The battery of the present invention has good cycle stability. (6) The battery of the present invention has a long service life. Other features and advantages of the present invention will be described in detail in the following specific embodiments. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 2 is an example of a top view of a positive electrode plate according to an embodiment of the present invention. [Figure 2] FIG. 10 is an example of a top view of a positive electrode plate according to another embodiment of the present invention. [Figure 3] 1 is an example of an actual image of a negative electrode plate disassembled from a battery manufactured in Example 1 of the present invention after 20 cycles (the color of the negative electrode plate is uniform and no lithium deposition occurs on the edge). [Figure 4] This is an example of an actual image of a negative electrode plate disassembled after 20 cycles of a battery manufactured in the comparative example (the dark colored areas in the edge region are lithium deposition, i.e., the lithium deposition problem occurred at the edge). DETAILED DESCRIPTION OF THE INVENTION

[0016] Specific embodiments of the present invention will be described in detail below. Note that the specific embodiments described here are merely for the purpose of explaining and introducing the present invention, and are not intended to limit the present invention.

[0017] A first aspect of the present invention discloses a positive electrode plate comprising a positive electrode current collector and a positive electrode active material layer provided on one or both sides of the positive electrode current collector, the positive electrode active material layer comprising a first active material layer and a second active material layer, the first active material layer being located in a longitudinally intermediate region of the surface of the positive electrode current collector, and the second active material layer being located on both longitudinal edge portions of the surface of the positive electrode current collector, or the second active material layer being located on the periphery of the surface of the positive electrode current collector.

[0018] Here, the first active material layer includes a first active material, the second active material layer includes a second active material, and the gram capacity of the first active material is higher than the gram capacity of the second active material.

[0019] To improve the surface density of positive and negative electrodes while maintaining charging capacity at high surface densities, the use of highly compressed fast-charging graphite materials for negative electrodes is currently being widely studied. This technology relies primarily on technological advances in graphite materials, but it has two drawbacks: (1) the gram capacity of graphite in highly compressed fast-charging graphite materials is significantly reduced, preventing significant improvements in energy density; (2) the actual charging capacity of highly compressed fast-charging graphite materials generally cannot exceed 1.5 C, and if it does exceed this limit, the compressed density must be 1.75 g / cm. 3 It's even harder to achieve.

[0020] On the other hand, according to an embodiment of the present invention, by optimizing the distribution of the positive electrode active material in the positive electrode plate based on an existing material system, positive electrode active material with different gram capacities is provided in the middle region and the edge region of the positive electrode plate, so that the active materials in the middle region and the edge region of the positive electrode plate have different gram capacities at the same voltage, and the gram capacity in the middle region is higher than the gram capacity in the edge region, which generates a kinetic difference and thereby improves the lithium deposition problem in the negative electrode plate.

[0021] By optimizing the positive electrode plate using the above-mentioned methods, it is possible to achieve a higher energy density and more stable cycle performance than conventional techniques in the positive electrode plate. Furthermore, to further improve the effect, one or more of the technical configurations can be further optimized.

[0022] As shown in FIGS. 1 and 2, the first active material layer is located in a middle region 1 in the longitudinal direction of the surface of the positive electrode current collector.

[0023] The second active material layer is located on both longitudinal edge portions 2 of the surface of the positive electrode current collector, or on the peripheral edge 3 of the surface of the positive electrode current collector. As shown in Fig. 1, the second active material layer is located on both longitudinal edge portions 2 of the surface of the positive electrode current collector, and as shown in Fig. 2, the second active material layer is located on the peripheral edge 3 of the surface of the positive electrode current collector.

[0024] In one example, the first active material layer region and the second active material layer region are connected or overlapped with each other, which can both improve the lithium deposition problem in the negative electrode plate.

[0025] The second active material layer and the first active material layer can be connected to each other. As shown in Figure 1, the first active material layer located in a central region 1 in the longitudinal direction of the surface of the positive electrode current collector and the second active material layer located on both longitudinal edge portions 2 of the surface of the positive electrode current collector are connected to each other, and a plain region 4 is located at one end. As shown in Figure 2, the first active material layer located in a central region 1 in the longitudinal direction of the surface of the positive electrode current collector and the second active material layer located on the peripheral edge 2 of the surface of the positive electrode current collector are connected to each other, and a plain region 4 is located at one end.

[0026] The first active material layer may include a first active material, and the second active material layer may include a second active material, wherein the gram capacity of the first active material is higher than the gram capacity of the second active material. When the gram capacity of the first active material is higher than the gram capacity of the second active material, the capacity exhibited by the edge region of the positive electrode plate is lower than the capacity exhibited by the middle region, thereby improving the lithium deposition problem at the edge of the negative electrode plate.

[0027] In one example, the gram capacity of the first active material is 125-190 mAh / g (e.g., 125 mAh / g, 130 mAh / g, 140 mAh / g, 150 mAh / g, 160 mAh / g, 170 mAh / g, 180 mAh / g, 190 mAh / g).

[0028] In one example, the gram capacity of the second active material is 120-190 mAh / g (e.g., 120 mAh / g, 125 mAh / g, 130 mAh / g, 140 mAh / g, 150 mAh / g, 160 mAh / g, 170 mAh / g, 180 mAh / g, 190 mAh / g).

[0029] In one example, the gram capacity of the first active material is higher than the gram capacity of the second active material by 0.1-240 mAh / g (e.g., 0.1 mAh / g, 0.5 mAh / g, 1 mAh / g, 5 mAh / g, 10 mAh / g, 15 mAh / g, 25 mAh / g, 30 mAh / g, 35 mAh / g, 40 mAh / g, 45 mAh / g, 50 mAh / g, 100 mAh / g, 150 mAh / g, 200 mAh / g, 240 mAh / g). When the gram capacity of the first active material is higher than the gram capacity of the second active material, the CB value of the middle region of the electrode plate is smaller than the CB value of the edge region of the electrode plate, assuming the same areal density. That is, in the negative electrode plate, the lithium insertion location points in the middle region of the negative electrode plate are fewer than the lithium insertion location points in the edge region, so there are enough lithium insertion location points in the edge region of the negative electrode plate, which effectively alleviates the lithium deposition problem at the edge of the negative electrode plate.

[0030] In one example, the gram capacity of the first active material is 0.8-60 mAh / g higher than the gram capacity of the second active material.

[0031] In the embodiments of the present disclosure, the gram capacity of a material is measured by a capacity test method using 0.2 C discharge. Specifically, the method includes placing the cell in an environment of 25±2°C, leaving it to stand for 4 hours, charging it to an upper limit voltage using a constant current and constant voltage of 0.2 C scaling, terminating at 0.05 C, leaving it to stand for another 5 minutes, and discharging it to a lower limit voltage using a constant current of 0.2 C scaling, recording the discharge capacity Q0, and calculating the active material content m0 ​​of the battery by calculating the weight of the positive electrode plate during the battery manufacturing process and subtracting the weight of the current collector and additional materials, and calculating the gram capacity G of the material as G=Q0 / m0.

[0032] According to a specific embodiment, the area of the region of the first active material layer is S1, the area of the region of the second active material layer is S2, and S1 and S2 satisfy the relationship of 0 < S2 / S1 ≤ 0.5 (for example, 0.001, 0.005, 0.01, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5). Since the gram capacity of the first active material layer is higher, by satisfying 0 < S2 / S1 ≤ 0.5, it can be ensured that the manufactured cell has a higher energy density.

[0033] As shown in FIG. 1, when the second active material layer is located at both side edges in the longitudinal direction on the surface of the positive electrode current collector, the area S2 of the region of the second active material layer is the sum of the areas of both side edges. As shown in FIG. 2, when the second active material layer is located on the periphery of the surface of the positive electrode current collector, the area S2 of the region of the second active material layer is the sum of the areas of the peripheral portions.

[0034] In one embodiment, 0.005 ≤ S2 / S1 ≤ 0.15.

[0035] According to a specific embodiment, the first active material layer and the second active material layer have the same areal density, that is, the areal density of the positive electrode plate is uniform and there is no phenomenon that the edge is thinner. Therefore, the flatness of the battery cell body is higher.

[0036] In one embodiment, the areal density of the positive electrode plate is 10 - 30 mg / cm 2 (for example, 10 mg / cm 2 , 12 mg / cm 2 , 15 mg / cm 2 , 18 mg / cm 2 , 20 mg / cm 2 , 21 mg / cm 2 , 22 mg / cm 2 , 23 mg / cm 2 , 24 mg / cm 2 , 25 mg / cm 2 , 26 mg / cm 2 , 27 mg / cm 2 , 28 mg / cm 2 , 29 mg / cm2 , 30 mg / cm 2 ) In the present invention, the areal density of the positive electrode plate refers to the areal density of one side of the positive electrode plate. When the positive electrode active material layer is present on one side of the positive electrode current collector, the areal density of the positive electrode plate is the areal density of that side (i.e., the side on which the positive electrode active material layer is present). When the positive electrode active material layer is present on both sides of the positive electrode current collector, the areal densities of both sides of the positive electrode plate are the same, and the areal density of the positive electrode plate is the areal density of either one of those sides. The positive electrode plate having an areal density that satisfies the above-mentioned range is advantageous for exhibiting capacity, improving energy density and cycle performance.

[0037] In one embodiment, the areal density of the positive electrode plate is 15-25 mg / cm 2 is.

[0038] According to a specific embodiment, the first active material layer and the second active material layer have the same compression density, that is, the compression density of the positive electrode plate is uniform.

[0039] In an embodiment of the present disclosure, the method for testing the areal density of a material is 電極板 Prepare a related electrode plate (coated on both sides) and measure its weight to determine that its area is S 電極板 Obtain the weight of the relevant electrode plate, m 電極板 and the surface density of the electrode plate C W =m 電極板 / S 電極板 and calculating / 2.

[0040] In one embodiment, the positive electrode plate has a compression density of 1-5 g / cm 3 (e.g., 1g / cm 3 , 2g / cm 3 , 2.5g / cm 3 , 3.0g / cm 3 , 3.5g / cm 3 , 4g / cm 3 , 4.5g / cm 3 , 5g / cm 3). In the present invention, the bonding density of the positive electrode plate refers to the bonding density of one side of the positive electrode plate. When the positive electrode active material layer is present on one side of the positive electrode current collector, the bonding density of the positive electrode plate is the bonding density of that side (i.e., the side on which the positive electrode active material layer is present). When the positive electrode active material layer is present on both sides of the positive electrode current collector, the bonding densities of both sides of the positive electrode plate are the same, and the bonding density of the positive electrode plate is the bonding density of either side. The positive electrode plate having a bonding density that satisfies the above range can improve the energy density of a battery cell.

[0041] In one example, the positive electrode plate has a compression density of 2.5-4.3 g / cm 3 is.

[0042] In the embodiment of the present disclosure, the method for measuring the bonding density of the material is to measure the total thickness of the electrode plate with a micrometer, subtract the thickness of the current collector, and then divide by 2 to obtain the thickness h0 of one side, and calculate the bonding density P of the electrode plate. D =C W and calculating / h0.

[0043] According to a specific embodiment, the first active material layer and the second active material layer have the same thickness. By making the first active material layer and the second active material layer have the same thickness, the consistency of the thickness of the positive electrode plate can be ensured, and the coating and pressing processes of the positive electrode plate can be controlled according to the normal coating standard, thereby ensuring no abnormalities in weight gain, thickness, and appearance.

[0044] In one embodiment, the median diameter D of the second active material 50 is the median diameter D of the first active material 50 By limiting the relative size relationship between the median diameters of the first active material and the second active material, it is possible to improve the compression density of the positive electrode plate and also contribute to improving the energy density of the entire battery cell.

[0045] In one embodiment, the median diameter D of the second active material 50and the median diameter D of the first active material 50 The difference between the median diameters of the first and second active materials is 2 μm or more (e.g., 2 μm, 5 μm, 10 μm, 15 μm). By further improving the relative size relationship between the median diameters of the first and second active materials, the advantages of the first and second active materials can be utilized in combination, thereby improving the energy density of the entire battery cell.

[0046] In the examples of the present disclosure, the median diameter D of the material was measured using a laser particle measurement instrument (LS-909). 50 Measure.

[0047] In one embodiment, the first active material comprises one or more of lithium cobalt oxide (LCO), lithium iron phosphate (LFP), lithium iron manganese phosphate, lithium manganese oxide, lithium nickel oxide, lithium nickel manganese oxide (LNMO), ternary materials (e.g., nickel cobalt aluminum ternary materials (NCA), nickel cobalt manganese ternary materials (NCM)), lithium nickel cobalt manganese aluminum oxide (NCMA), and lithium-rich manganese-based materials (LRM).

[0048] In one embodiment, the second active material comprises one or more of lithium cobalt oxide (LCO), lithium iron phosphate (LFP), lithium iron manganese phosphate, lithium manganese oxide, lithium nickel oxide, lithium nickel manganese oxide (LNMO), ternary materials (e.g., nickel cobalt aluminum ternary materials (NCA), nickel cobalt manganese ternary materials (NCM)), lithium nickel cobalt manganese aluminum oxide (NCMA), and lithium-rich manganese-based materials (LRM).

[0049] According to a specific embodiment, the first active material comprises a ternary material.

[0050] According to a specific embodiment, the first active material includes one or more of a nickel-cobalt-aluminum ternary material and a nickel-cobalt-manganese ternary material.

[0051] According to a specific embodiment, the second active material includes lithium cobalt oxide.

[0052] According to a specific embodiment, the first active material includes one or more of a nickel-cobalt-aluminum ternary material and a nickel-cobalt-manganese ternary material, and the second active material includes lithium cobalt oxide.

[0053] According to a specific embodiment, the first active material comprises a monocrystalline ternary material and / or a polycrystalline ternary material.

[0054] According to a specific embodiment, the nickel-cobalt-aluminum ternary material may include a single crystal ternary material and / or a polycrystalline ternary material, and the nickel-cobalt-manganese ternary material may include a single crystal ternary material and / or a polycrystalline ternary material.

[0055] In one embodiment, the formula of the single crystal ternary material is Li a Ni x Co y Mn 1-x-y A k O2 (0≦x≦1, 0≦y≦1, 0.9≦a≦1.1, 0≦k≦0.05), and A is a doping element. Preferably, A is selected from one or more of Al, Mg, Ti, La, Zr, V, Nb, Si, F, O, B, Cu, Sn, N, P, Y, Zr, N, C, Au, and Ag.

[0056] In one embodiment, the formula of the single crystal ternary material is Li a Ni x Co y Al 1-x-y A k O2 (0≦x≦1, 0≦y≦1, 0.9≦a≦1.1, 0≦k≦0.05), and A is a doping element. Preferably, A is selected from one or more of Al, Mg, Ti, La, Zr, V, Nb, Si, F, O, B, Cu, Sn, N, P, Y, Zr, N, C, Au, and Ag.

[0057] In one embodiment, the crystal structure of the single crystal ternary material is a layered structure.

[0058] In one embodiment, the median diameter D of the single crystal ternary material 50 is 1-6 μm (e.g., 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm). 50 By lowering it to this range, the reaction active area can be increased, and the magnification performance of the single crystal ternary material can be improved to a certain extent.

[0059] In one embodiment, the median diameter D of the single crystal ternary material 50 is 2-4 μm.

[0060] In the examples of the present invention, unless otherwise specified, 50 is always DV 50 Refers to...

[0061] In one embodiment, the formula of the polycrystalline ternary material is Li a Ni x Co y Mn 1-x-y A k O2 (0≦x≦1, 0≦y≦1, 0.9≦a≦1.1, 0≦k≦0.05), and A is selected from one or more of Al, Mg, Ti, Y, and Zr.

[0062] In one embodiment, the formula of the polycrystalline ternary material is Li a Ni x Co y Al 1-x-y A k O2 (0≦x≦1, 0≦y≦1, 0.9≦a≦1.1, 0≦k≦0.05), and A is selected from one or more of Al, Mg, Ti, Y, and Zr.

[0063] In one embodiment, the crystalline structure of the polycrystalline ternary material is a layered structure.

[0064] In one embodiment, the median diameter D of the polycrystalline ternary material 50The range is 7-20 μm (for example, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 15 μm, 16 μm, 17 μm, 20 μm). By increasing the median diameter of the polycrystalline material to this range, the high-temperature stability of the polycrystalline material can be improved and sufficient magnification performance can be ensured.

[0065] In one embodiment, the median diameter D of the polycrystalline ternary material 50 is 8-12 μm.

[0066] In one embodiment, the median diameter D of the lithium cobalt oxide 50 is 5-25 μm (e.g., 5 μm, 7 μm, 10 μm, 12 μm, 15 μm, 17 μm, 20 μm, 22 μm, 25 μm).

[0067] In one embodiment, the median diameter D of the lithium cobalt oxide 50 is 12-18 μm.

[0068] According to a specific embodiment, the first active material layer includes a first conductive agent and a first adhesive.

[0069] In one embodiment, the first conductive agent is selected from one or more of carbon black, mesophase microspheres, acetylene black, ketjen black, conductive graphite, conductive carbon fiber, carbon nanotubes (CNTs), metal powder, carbon fiber, single-walled carbon nanotubes, and multi-walled carbon nanotubes.

[0070] In one embodiment, the first adhesive is selected from one or more of polyvinylidene fluoride (PVDF), sodium carboxymethyl cellulose, polyurethane, polyvinyl alcohol, polyvinylidene fluoride, vinylidene fluoride-fluorinated olefin copolymer, and polymethyl methacrylate (PMMA).

[0071] In one embodiment, based on the total weight of the first active material layer, the weight content of the first active material is 80-99.8 wt%, the weight content of the first conductive agent is 0.1-10 wt%, and the weight content of the first adhesive is 0.1-10 wt%.

[0072] In one embodiment, based on the total weight of the first active material layer, the weight content of the first active material is 90-99.6 wt%, the weight content of the first conductive agent is 0.2-5 wt%, and the weight content of the first adhesive is 0.2-5 wt%.

[0073] According to a specific embodiment, the second active material layer includes a second conductive agent and a second adhesive.

[0074] In one embodiment, the second conductive agent is selected from one or more of carbon black, mesophase microspheres, acetylene black, ketjen black, conductive graphite, conductive carbon fiber, carbon nanotubes (CNTs), metal powder, carbon fiber, single-walled carbon nanotubes, and multi-walled carbon nanotubes.

[0075] In one embodiment, the second adhesive is selected from one or more of polyvinylidene fluoride (PVDF), sodium carboxymethyl cellulose, polyurethane, polyvinyl alcohol, polyvinylidene fluoride, vinylidene fluoride-fluorinated olefin copolymer, and polymethyl methacrylate (PMMA).

[0076] In one embodiment, based on the total weight of the second active material layer, the weight content of the second active material is 80-99.8 wt%, the weight content of the second conductive agent is 0.01-10 wt%, and the weight content of the second adhesive is 0.01-10 wt%.

[0077] In one embodiment, based on the total weight of the second active material layer, the weight content of the second active material is 90-99.6 wt%, the weight content of the second conductive agent is 0.02-5 wt%, and the weight content of the second adhesive is 0.02-5 wt%.

[0078] A second aspect of the present invention discloses a battery, the positive electrode plate of which is the positive electrode plate according to the first aspect of the present invention.

[0079] The materials and manufacturing methods of the battery other than the positive electrode plate can be according to the methods known in the art, and all of them can achieve the effects of high energy density and stable cycle performance.

[0080] In one embodiment, the battery comprises a negative plate.

[0081] The negative electrode plate may be a conventional negative electrode plate in the art, for example, the negative electrode plate includes a negative electrode current collector and a negative electrode active material layer disposed on one or both sides of the negative electrode current collector. The negative electrode active material layer includes a negative electrode active material.

[0082] In one embodiment, the negative electrode active material is selected from one or more of carbon-based negative electrode materials (eg, artificial graphite, natural graphite, mesocarbon microspheres, hard carbon, and soft carbon) and silicon-based negative electrode materials.

[0083] In one embodiment, the positive electrode plate comprises a positive electrode current collector and a positive electrode active material layer provided on one or both sides of the positive electrode current collector, the positive electrode active material layer comprising a first active material layer and a second active material layer, the first active material layer being located in a longitudinally intermediate region of the surface of the positive electrode current collector, and the second active material layer being located on both longitudinal edge portions of the surface of the positive electrode current collector, or the second active material layer being located on the periphery of the surface of the positive electrode current collector, wherein the first active material layer contains a first active material and the second active material layer contains a second active material.

[0084] In one embodiment, the region of the first active material layer and the region of the second active material layer are connected or overlap with each other.

[0085] Other descriptions of the positive electrode plate may refer to the first aspect and will not be described again here.

[0086] According to a specific embodiment, the battery includes a first area and a second area. The first area is an area including the first active material layer. The CB value of the first area is CB1 = (the areal density of the negative electrode plate × the gram capacity of the negative active material × the content of the negative active material) / (the areal density of the positive electrode plate × the gram capacity of the first active material in the first area × the content of the first active material in the first area). The second area is an area including the second active material layer. The CB value of the second area is CB2 = (the areal density of the negative electrode plate × the gram capacity of the negative active material × the content of the negative active material) / (the areal density of the positive electrode plate × the gram capacity of the second active material in the second area × the content of the second active material in the second area), and CB1 < CB2.

[0087] By optimizing the positive electrode plate and providing different active materials in the middle region and the edge region of the positive electrode plate, a difference is generated between CB1 of the first area and CB2 of the second area of the battery. Thereby, the problem that lithium is deposited at the edge at a high areal density of the battery can be improved, and the effect of achieving both a high energy density and stable cycle performance can be achieved.

[0088] In one embodiment, 0 < CB2 - CB1 ≤ 0.15 (for example, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15).

[0089] In one embodiment, 0.0008 ≤ CB2 - CB1 ≤ 0.06.

[0090] According to a specific embodiment, the areal density of the negative electrode plate is 4 - 16 mg / cm 2 (for example, 10 mg / cm 2 , 11 mg / cm2 , 12 mg / cm 2 , 13 mg / cm 2 , 14 mg / cm 2 , 15 mg / cm 2 , 16 mg / cm 2 In the present invention, the areal density of the negative electrode plate refers to the areal density of one side of the negative electrode plate. When the negative electrode active material layer is present on one side of the negative electrode current collector, the areal density of the negative electrode plate is the areal density of that one side. When the negative electrode active material layer is present on both sides of the negative electrode current collector, the areal densities of both sides of the negative electrode plate are the same, and the areal density of the negative electrode plate is the areal density of one side thereof.

[0091] In one embodiment, the areal density of the negative electrode plate is 10-13 mg / cm 2 is.

[0092] In one embodiment, the negative electrode plate has a compression density of 1.5-1.9 g / cm 3 (1.5g / cm 3 , 1.6g / cm 3 , 1.7g / cm 3 , 1.8g / cm 3 , 1.9g / cm 3 ) In the present invention, the bonding density of the negative electrode plate refers to the bonding density of one side of the negative electrode plate. When the negative electrode active material layer is present on one side of the negative electrode current collector, the bonding density of the negative electrode plate refers to the bonding density of that one side. When the negative electrode active material layer is present on both sides of the negative electrode current collector, the bonding densities of both sides of the negative electrode plate are the same, and the bonding density of the negative electrode plate refers to the bonding density of one side. Within this range, the energy density of the positive electrode plate according to the present invention and a battery manufactured from the negative electrode plate can be improved.

[0093] In one embodiment, the negative electrode plate has a compression density of 1.7-1.8 g / cm 3 Within this range, the energy density of the battery cell can be further improved.

[0094] In one embodiment, the negative electrode active material layer includes a third conductive agent and a third adhesive.

[0095] In one embodiment, the third conductive agent is selected from one or more of carbon black, mesophase microspheres, acetylene black, ketjen black, conductive graphite, conductive carbon fiber, carbon nanotubes (CNTs), metal powder, carbon fiber, single-walled carbon nanotubes, and multi-walled carbon nanotubes.

[0096] In one embodiment, the third adhesive is selected from one or more of styrene-butadiene rubber (SBR), sodium carboxymethyl cellulose, polyurethane, polyvinyl alcohol, and polymethyl methacrylate (PMMA).

[0097] In one embodiment, based on the total weight of the negative electrode active material layer, the weight content of the negative electrode active material is 80-99.8 wt%, the weight content of the third conductive agent is 0.1-10 wt%, and the weight content of the third adhesive is 0.1-10 wt%.

[0098] In one embodiment, based on the total weight of the negative electrode active material layer, the weight content of the negative electrode active material is 90-99.6 wt%, the weight content of the third conductive agent is 0.2-5 wt%, and the weight content of the third adhesive is 0.2-5 wt%.

[0099] In one embodiment, the negative electrode active material layer is obtained by coating a negative electrode active material slurry on the surface of the negative electrode current collector.

[0100] In one embodiment, the solid content of the negative electrode active material slurry is 40 wt%-49 wt% (e.g., 40 wt%, 41 wt%, 42 wt%, 43 wt%, 44 wt%, 45 wt%, 46 wt%, 47 wt%, 48 wt%, 49 wt%).

[0101] In one embodiment, the viscosity of the negative electrode active material slurry is 2000 to 6000 mPa·s (for example, 2000 mPa·s, 3000 mPa·s, 4000 mPa·s, 5000 mPa·s, or 6000 mPa·s).

[0102] In the examples of the present disclosure, the viscosity of the slurry is measured with a viscometer (NDJ-5S / 8S).

[0103] By including the positive electrode plate according to the present invention, the battery according to the present invention has improved energy density, improved cycle stability, and a longer cycle life.

[0104] The present invention will be described in detail below based on the examples. The examples described in the present invention are only some of the examples of the present invention, and are not all of the examples. All other examples obtained by those skilled in the art based on the examples of the present invention without creative labor fall within the scope of protection of the present invention.

[0105] The following examples are used to illustrate the manufacture of positive plates according to the present invention. Example 1a (1) Preparation of ingredients Positive electrode current collector: 10 μm aluminum foil First active material slurry: 97 parts by weight of the first active material (nickel-cobalt-manganese ternary material, D 50 Ternary polycrystalline materials with a D of 10 μm-12 μm 50 The ternary single crystal material has a particle size of 2 μm-4 μm and a gram capacity of 190 mAh / g@4.2V (where @4.2V indicates that the gram capacity is measured at a voltage of 4.2V), 1.5 parts by weight of a first conductive agent (multi-walled carbon nanotubes), and 1.5 parts by weight of a first adhesive (PVDF). Second active material slurry: 97 parts by weight of second active material (lithium cobalt oxide material, D 50 As shown in Table 1, the gram capacity is 160 mAh / g@4.2 V), 1.5 parts by weight of a second conductive agent (multi-walled carbon nanotubes), 1.5 parts by weight of a second adhesive (PVDF) (2) Manufacturing of positive electrode plates The produced first active material slurry and second active material slurry were applied to a positive electrode current collector using a press-type coating device to obtain a first active material layer located in the middle region in the longitudinal direction and second active material layers located on both sides of the first active material layer. The areal density of both the first active material layer and the second active material layer was 22 mg / cm. 2 The compression density of the first active material layer and the second active material layer was 3.8 g / cm 3 As shown in Figure 1, the coating width of the first active material layer is 570 mm, and the coating width of the second active material layer is 30 mm (15 mm on each side). The sum of the coating widths of the first active material layer and the second active material layer is 600 mm, and the first active material layer and the second active material layer have the same coating length and thickness. After the coating process is completed, the positive electrode plate is completed.

[0106] Example Group 1b In this example group, the D of the first active material layer and the second active material layer 50 It is used to explain the effects that occur when changes in

[0107] The examples in this group are based on Example 1a, but the difference is that the D 50 is 14 μm, and D of the second active material layer is 50 The specific values ​​are shown in Table 1.

[0108] Example Group 2 This group of examples is used to illustrate the effects that occur when S2 / S1 is varied.

[0109] The examples in this group are based on Example 1, but the difference is that the coating width of the second active material layer is changed, as shown in Table 1.

[0110] Example Group 3 This group of examples is used to illustrate the effects that occur when the gram capacity of the first active material and / or the second active material is varied.

[0111] The examples in this group are based on Example 1, but the gram capacity of the first active material and / or the second active material is changed, as shown in Table 1.

[0112] Example Group 4 This group of examples is used to illustrate the effects that occur when the areal density of the positive plates is varied.

[0113] The examples in this group are based on Example 1, but the difference is that the areal density of the positive electrode plate is changed, as shown in Table 1.

[0114] Example Group 5 This group of examples is used to illustrate the effects that occur when the first active material and / or the second active material are varied.

[0115] The examples in this group are based on Example 1, but the difference is that the first active material and / or the second active material are changed, as shown in Table 1.

[0116] Comparative Example 1 This was carried out based on Example 1, except that the second active material was changed to the nickel-cobalt-manganese ternary material used in Example 1.

[0117] Comparative Example 2 This is based on Example 1, but the difference is that the second active material is changed to the lithium cobalt oxide used in Example 1, and the second active material is changed to the nickel-cobalt-manganese ternary material used in Example 1.

[0118] Table 1 JPEG0007763884000001.jpg128170* indicates that it is the same as in the first embodiment.

[0119] Manufacturing example Using the positive electrode plates manufactured in the examples and comparative examples, batteries were manufactured according to the following procedure. (1) Manufacturing of positive electrode plates The positive electrode plates obtained in the above-mentioned Examples and Comparative Examples are used. (2) Manufacturing of negative electrodes A negative electrode active material slurry was prepared with a graphite:adhesive:CMC:carbon black ratio of 96.5 wt %, 1.5 wt %, 1.5 wt %, and 0.5 wt %. After the slurry preparation was completed, the coating process was carried out according to the coating management control standard. The surface density of the negative electrode plate was 12.0 mg / cm. 2 and the compression density is 1.8 g / cm 3 is. (3) Separator A commercially available 5+2+2 oil-based separator manufactured by Asahi Kasei is used. (4) Electrolyte An electrolyte solution is obtained by dissolving lithium hexafluorophosphate (LiPF6) in a mixed solvent consisting of ethylene carbonate (EC), dimethyl carbonate (DEC), and ethyl methyl carbonate (EMC) (the weight ratio of the three is 1:1:1). (5) Battery manufacturing According to the conventional manufacturing process of polymer lithium-ion batteries, pressing is performed according to the process design to ensure that the bonding density of the positive and negative electrodes meets the process requirements. Then, sheet manufacturing (tab welding) and winding (positive electrode + separator + negative electrode) are performed. Next, packaging, injection, and chemical formation are performed, followed by secondary sealing to ensure that the residual liquid coefficient is 1.3 or higher. Finally, classification and selection are performed to complete the production of pouch-type polymer lithium-ion batteries.

[0120] Test Example The following tests were carried out on the batteries obtained in the examples and comparative examples. (1) 25℃ cycle performance test The battery is subjected to 700 charge / discharge cycles at 25°C and 1C within the charge / discharge cutoff voltage range. The discharge capacity at the first cycle of the test is denoted as x1mAh, and the discharge capacity at the Nth cycle is denoted as y1mAh. Dividing the capacity at the Nth cycle by the capacity at the first cycle gives the cycle capacity retention rate at the Nth cycle, R1 = y1 / x1. (2) 45℃ cycle performance test The battery is subjected to 500 charge / discharge cycles at 45°C and 1C within the charge / discharge end voltage range. The discharge capacity at the first cycle of the test is recorded as A1mAh, and the discharge capacity at the Nth cycle is recorded as B1mAh. Dividing the capacity at the Nth cycle by the capacity at the first cycle gives the cycle capacity retention rate at the Nth cycle, R2 = B1 / A1. (3) Lithium deposition test Disassemble the battery after 20 cycles at 25°C and check the state of lithium deposition on the negative electrode plate. If no lithium is deposited, it is indicated as "absent," and if lithium is deposited, it is indicated as "present." FIG. 3 shows an actual image of the negative electrode plate disassembled from the battery manufactured in Example 1 of the present disclosure after 20 cycles. The negative electrode plate has a uniform color and no lithium deposition on the edge. FIG. 4 shows an actual image of the negative electrode plate of the battery manufactured in the comparative example, disassembled after 20 cycles. The dark colored areas in the edge region are lithium deposition, meaning that the lithium deposition problem occurred at the edge. (4) Energy density test 1) The dimensions of the battery cell model are 4.0 (mm, thickness, H) × 60 (mm, width, W) × 90 (mm, height, L), i.e., the volume V of the battery cell = thickness × width × height. 2) After leaving the battery cell in an environment of 25±3°C for 2 hours, charge the battery cell to full charge at a constant current and voltage of 0.5C until the final current is 0.025C. After leaving the battery cell for 5 minutes, discharge the battery cell to 3.0V at a constant current of 0.2C. Record the discharge capacity Q and plateau voltage U. 3) The formula for calculating the volumetric energy density of a battery cell is ED=Q×U / (H×W×L).

[0121] The results obtained are recorded in Table 2. Table 2 JPEG0007763884000002.jpg112170

[0122] As can be seen from Table 2, when comparing the Comparative Example and the Examples, when a battery was manufactured using the positive electrode plate according to the Examples, both the energy density and the cycle capacity retention rate were maintained, and the problem of lithium deposition at the edge of the negative electrode plate was improved. In other words, the positive electrode plate according to the present invention and the battery including the positive electrode plate improved the problem of lithium deposition at the negative electrode plate by optimizing the distribution of the positive electrode active material in the positive electrode plate, thereby improving the service life of the battery.

[0123] Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, the technical solutions of the present invention may be easily modified in various ways, for example, each technical configuration may be combined in any other suitable form. These simple modifications and combinations should also be considered as the disclosure content of the present invention and fall within the protection scope of the present invention.

Claims

1. A positive electrode plate, the positive electrode plate comprises a positive electrode current collector and a positive electrode active material layer provided on one or both sides of the positive electrode current collector, the positive electrode active material layer comprises a first active material layer and a second active material layer, the first active material layer being located in a middle region in a longitudinal direction of the surface of the positive electrode current collector, and the second active material layer being located on both edge portions in the longitudinal direction of the surface of the positive electrode current collector, or the second active material layer being located on a peripheral edge of the surface of the positive electrode current collector; the first active material layer includes a first active material, the second active material layer includes a second active material, and the gram capacity of the first active material is higher than the gram capacity of the second active material; the gram capacity of the first active material is 185-190 mAh / g; The area of ​​the first active material layer region is S １ and the area of ​​the region of the second active material layer is S ２ and S １ and S ２ is 0<S ２ / S １ ≦0.5, The first active material layer and the second active material layer have the same surface density, and the surface density of the positive electrode plate is 10-30 mg / cm ２ That is, A positive electrode plate characterized by:

2. The region of the first active material layer and the region of the second active material layer are connected to or overlap each other. The positive electrode plate according to claim 1 .

3. The gram capacity of the second active material is 120-190 mAh / g, The gram capacity of the first active material is 0.8-60 mAh / g higher than the gram capacity of the second active material. The positive electrode plate according to claim 1 .

4. the first active material layer and the second active material layer have the same compression density; The compression density of the positive electrode plate is 1-5 g / cm ３ is The positive electrode plate according to claim 1 .

5. The first active material layer and the second active material layer have the same thickness. The positive electrode plate according to claim 1 .

6. The median diameter D of the second active material ５０ is the median diameter D of the first active material ５０ Greater than The positive electrode plate according to claim 1 .

7. The difference between the median diameter of the second active material and the median diameter of the first active material is 2 μm or more. The positive electrode plate according to claim 1 .

8. the first active material comprises one or more of lithium cobalt oxide, lithium iron phosphate, lithium manganese iron phosphate, lithium manganate, lithium nickel oxide, lithium nickel manganate, nickel cobalt aluminum ternary material, nickel cobalt manganese ternary material, nickel cobalt manganese aluminum lithium oxide, and lithium-rich manganese-based materials; and / or the second active material comprises one or more of lithium cobalt oxide, lithium iron phosphate, lithium manganese iron phosphate, lithium manganate, lithium nickel oxide, lithium nickel manganate, nickel cobalt aluminum ternary material, nickel cobalt manganese ternary material, nickel cobalt manganese aluminum lithium oxide, and lithium rich manganese based materials. The positive electrode plate according to claim 1 .

9. The first active material comprises one or more of a nickel-cobalt-aluminum ternary material and a nickel-cobalt-manganese ternary material, and the second active material comprises lithium cobalt oxide. The positive electrode plate according to claim 1 .

10. The nickel-cobalt-aluminum ternary material and the nickel-cobalt-manganese ternary material include single crystal ternary materials and / or polycrystalline ternary materials. The positive electrode plate according to claim 9 .

11. The median diameter D of the single crystal ternary material ５０ is 1-6 μm, The median diameter D of the polycrystalline ternary material ５０ is 7-20 μm, The median diameter D of the lithium cobalt oxide ５０ is 5-25 μm The positive electrode plate according to claim 10 .

12. A battery, The battery comprises a positive electrode plate according to any one of claims 1 to 11. A battery characterized by:

13. the battery further comprises a negative electrode plate; the positive electrode plate comprises a positive electrode current collector and a positive electrode active material layer provided on one or both sides of the positive electrode current collector, the positive electrode active material layer comprising a first active material layer and a second active material layer, the first active material layer being located in a central region in a longitudinal direction of the surface of the positive electrode current collector, the second active material layer being located on both edge portions in the longitudinal direction of the surface of the positive electrode current collector, or the second active material layer being located on a peripheral edge of the surface of the positive electrode current collector, the first active material layer including a first active material, and the second active material layer including a second active material; the battery comprises a first area and a second area; The first area is a region including the first active material layer, and the CB value of the first area is CB １ = (area density of negative electrode plate × gram capacity of negative electrode active material × content of negative electrode active material) / (area density of positive electrode plate × gram capacity of first active material in first area × content of first active material in first area), The second area is a region including the second active material layer, and the CB value of the second area is CB ２ = (area density of negative electrode plate × gram capacity of negative electrode active material × content of negative electrode active material) / (area density of positive electrode plate × gram capacity of second active material in second area × content of second active material in second area), and CB １ <CB ２ is The positive electrode plate according to claim 12 .

14. 0<CB ２ -CB １ ≦0.15 The positive electrode plate according to claim 13 .

15. The surface density of the negative electrode plate is 4-16 mg / cm ２ and The negative electrode plate has a compression density of 1.5-1.9 g / cm ３ is The positive electrode plate according to claim 13 .

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