Laminated cell and secondary battery

Abstract

The utility model relates to the technical field of lithium ion batteries, and discloses a laminated battery cell and a secondary battery. The outermost-layer pole piece is located on the outer side of the inner-layer pole piece, the outermost-layer pole piece comprises an outermost-layer current collector and an outermost-layer active material layer arranged on the surface of one side of the outermost-layer current collector, and the outermost-layer active material layer is arranged close to the inner-layer pole piece; and the outermost current collector is a foam current collector or a composite current collector. According to the utility model, the current collector on the outermost layer has larger resistivity, and the thickness of the current collector on the outermost layer can be set to be larger, so that the strength of the current collector on the outermost layer is improved, the current collector on the outermost layer has higher bending resistance, and the pole piece on the outermost layer is prevented from being curled; and meanwhile, the current collector on the outermost layer has relatively high resistivity, so that even if the thickness of the current collector on the outermost layer is increased, the internal resistance of the current collector on the outermost layer is not reduced too much, and the problem of lithium precipitation of the cathode on the outermost layer or the cathode corresponding to the anode on the outermost layer in the laminated cell is solved.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium-ion batteries, in particular to a laminated battery core and a secondary battery. Background Art

[0002] Lithium-ion secondary batteries have high charge and discharge performance, no memory effect, and are environmentally friendly. They are widely used in electric vehicles and consumer electronics. In recent years, the application of lithium-ion batteries in various fields has become more and more extensive. The operating environment of batteries is complex, and higher performance requirements are placed on batteries. For laminated battery cells, in order to avoid curling of the outermost electrode, the thickness of the current collector of the outermost electrode will be thicker than the thickness of the current collector of the inner electrode. However, due to the different thicknesses of the outermost current collector and the inner current collector, the internal resistance of the outermost current collector is smaller, and the current density obtained is greater, which will cause the outermost negative electrode or the negative electrode corresponding to the outermost positive electrode to be prone to lithium deposition. Utility Model Content

[0003] In view of this, the present invention provides a laminated battery cell and a secondary battery to solve the problem that the outermost negative electrode of the existing laminated battery cell or the negative electrode corresponding to the outermost positive electrode is prone to lithium deposition.

[0004] In the first aspect, the utility model provides a laminated battery cell, comprising a first electrode piece, a diaphragm and a second electrode piece arranged in a stacked manner, the first electrode piece and the second electrode piece have opposite polarities, the first electrode piece comprising: an inner electrode piece; an outermost electrode piece, located on the outside of the inner electrode piece, the outermost electrode piece comprising an outermost current collector and an outermost active material layer arranged on one side surface of the outermost current collector, the outermost active material layer being arranged close to the inner electrode piece; wherein the outermost current collector is a foam current collector or a composite current collector.

[0005] In an optional embodiment, the outermost electrode is a positive electrode, and the outermost current collector is a foam aluminum current collector or a composite aluminum current collector.

[0006] In an optional embodiment, the porosity of the aluminum foam current collector is 20% to 80%; and / or the resistivity of the aluminum foam current collector is 2.82×10 -7 Ω·m to 2.82×10 -6 Ω·m; and / or, the thickness of the foam aluminum current collector is 10 μm to 30 μm.

[0007] In an optional embodiment, the composite aluminum current collector includes a first bonding layer and aluminum layers disposed on two opposite sides of the first bonding layer, the thickness of the composite aluminum current collector is 5 μm to 30 μm, and the thickness of the aluminum layer is 0.5 μm to 5 μm.

[0008] In an optional embodiment, the outermost electrode is a negative electrode, and the outermost current collector is a foam copper current collector or a composite copper current collector.

[0009] In an optional embodiment, the porosity of the copper foam current collector is 20% to 80%; and / or the resistivity of the copper foam current collector is 6.75×10 -7 Ω·m to 6.75×10 -6 Ω·m; and / or, the thickness of the foam copper current collector is 5 μm to 30 μm.

[0010] In an optional embodiment, the composite copper current collector includes a second bonding layer and copper layers disposed on two opposite sides of the second bonding layer. The thickness of the composite copper current collector is 5 μm to 30 μm, and the thickness of the copper layer is 0.5 μm to 3 μm.

[0011] In an optional embodiment, the inner electrode sheet includes an inner current collector and an inner active material layer provided on at least one side surface of the inner current collector; the inner electrode sheet is a positive electrode sheet, and the inner current collector is an aluminum foil current collector, or a foamed aluminum current collector, or a composite aluminum current collector; or, the inner electrode sheet is a negative electrode sheet, and the inner current collector is a copper foil current collector, or a foamed copper current collector, or a composite copper current collector; the thickness of the outermost current collector is H1, the thickness of the inner current collector is H2, the resistivity of the outermost current collector is ρ1, and the resistivity of the inner current collector is ρ2, satisfying: ρ1 / ρ2≥H1 / H2; wherein, the units of H1 and H2 are μm, the units of ρ1 and ρ2 are Ω·m, the value range of H1 is 10μm to 30μm, the value range of H2 is 5μm to 15μm, and the value range of ρ1 is 6.75×10 -7 Ω·m to 2.82×10 -6 Ω·m, the value range of ρ2 is 6.75×10 -8 Ω·m to 2.82×10 -6 Ω·m.

[0012] In an optional embodiment, the thickness of the outermost active material layer is 15 μm to 150 μm; and / or, the first electrode is a positive electrode and the second electrode is a negative electrode; or, the first electrode is a negative electrode and the second electrode is a positive electrode.

[0013] In a second aspect, the present invention further provides a secondary battery comprising the above-mentioned laminated battery cell.

[0014] The technical solution of this application has the following advantages:

[0015] The laminated battery cell provided in the present application adopts a foam current collector or a composite current collector for the outermost current collector, so that the outermost current collector has a larger resistivity. Therefore, the outermost current collector can be set to a larger thickness, thereby improving the self-strength of the outermost current collector, making the outermost current collector have a higher bending resistance, and avoiding curling of the outermost electrode; at the same time, because the outermost current collector has a larger resistivity, even if the thickness of the outermost current collector is increased, it will not cause the internal resistance of the outermost current collector to decrease too much, thereby solving the problem of lithium plating in the outermost negative electrode or the negative electrode corresponding to the outermost positive electrode in the laminated battery cell.

[0016] Additional aspects and advantages of the embodiments of the present application will be described and shown in part in the subsequent description, or explained through the implementation of the embodiments of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 This is a schematic structural diagram of the outermost pole piece of an embodiment of the present utility model;

[0019] Figure 2 This is a schematic structural diagram of the inner electrode of an embodiment of the present utility model;

[0020] Figure 3 This is a schematic structural diagram of a laminated battery cell according to an embodiment of the present invention.

[0021] Description of reference numerals:

[0022] 1. Inner electrode; 11. Inner current collector; 12. Inner active material layer; 2. Outermost electrode; 21. Outermost current collector; 22. Outermost active material layer; 3. Diaphragm. DETAILED DESCRIPTION

[0023] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0024] The present application provides a laminated battery cell and a secondary battery, which can effectively solve the problem of lithium plating on the outermost negative electrode or the negative electrode corresponding to the outermost positive electrode in the laminated battery cell. Figures 1 to 3 , describing the embodiments of the present utility model.

[0025] According to an embodiment of the present invention, on the one hand, a laminated battery cell is provided, comprising a first electrode sheet, a separator 3, and a second electrode sheet arranged in a stacked manner. The first electrode sheet and the second electrode sheet have opposite polarities. The first electrode sheet comprises an inner electrode sheet 1 and an outermost electrode sheet 2, with the outermost electrode sheet 2 being located outside the inner electrode sheet 1. The outermost electrode sheet 2 comprises an outermost current collector 21 and an outermost active material layer 22 disposed on one side of the outermost current collector 21, with the outermost active material layer 22 being disposed adjacent to the inner electrode sheet 1. The outermost current collector 21 is a foam current collector or a composite current collector.

[0026] When using the laminated battery cell of this embodiment, a foam current collector or a composite current collector is used for the outermost current collector 21, so that the outermost current collector 21 has a larger resistivity. Therefore, the outermost current collector 21 can be set to a larger thickness, thereby improving the self-strength of the outermost current collector 21, making the outermost current collector 21 have a higher bending resistance, and avoiding curling of the outermost electrode 2; at the same time, because the outermost current collector 21 has a larger resistivity, even if the thickness of the outermost current collector 21 increases, it will not cause the internal resistance of the outermost current collector 21 to decrease too much, thereby solving the problem of lithium plating in the outermost negative electrode or the negative electrode corresponding to the outermost positive electrode in the laminated battery cell.

[0027] It should be noted that, during the stacking process, the laminated battery cells are stacked in the order of first electrode piece-diaphragm 3-second electrode piece-diaphragm 3-first electrode piece-diaphragm 3...diaphragm 3-second electrode piece-diaphragm 3-first electrode piece. Therefore, the first electrode piece stacked first and the last electrode piece stacked last are both the outermost electrode piece 2, and the first electrode piece between the first electrode piece stacked first and the last electrode piece stacked last is the inner electrode piece 1.

[0028] It is worth noting that in the related art, although batteries using laminated cells have faster charging speeds, due to process requirements, the outermost current collector 21 can often only be coated on one side during the preparation of the laminated cell. Single-sided coating will result in uneven stress distribution of the current collector and easy curling. Therefore, for laminated cells, in order to avoid curling of the outermost electrode 2, the thickness of the current collector of the outermost electrode 2 will be thicker than that of the current collector of the inner electrode 1, thereby reducing the internal resistance of the current collector of the outermost electrode 2 compared to the internal resistance of the current collector of the inner electrode 1, increasing the current density of the current collector of the outermost electrode 2, and increasing the possibility of lithium plating. Therefore, in this embodiment, the outermost current collector 21 is a foam current collector or a composite current collector, which increases the resistivity of the outermost current collector 21. Therefore, although the thickness of the outermost current collector 21 increases, it will not cause the internal resistance of the outermost current collector 21 to be too small compared to the internal resistance of the current collector of the inner electrode 1, thus avoiding the occurrence of lithium plating problems.

[0029] It is understood that internal resistance is the internal resistance, and resistivity is a physical quantity that describes the conductive properties of a material. According to the resistance law, the internal resistance of a conductor is inversely proportional to its cross-sectional area. The main function of the current collector is to collect and transmit current. When the thickness of the current collector increases, the conductive area also increases, which reduces the internal resistance of the current collector. Lithium deposition is the phenomenon in which lithium ions precipitate on the surface of the negative electrode to form metallic lithium during the charging process of lithium-ion batteries.

[0030] It is worth noting that the active slurry is vacuum impregnated into the internal pores of the foam current collector, and then dried, rolled, and slit to produce the pole piece. As a result, the contact area between the active material and the current collector in the pole piece is effectively increased, increasing the coating amount of the lithium-ion battery and effectively improving the volumetric energy density of the lithium-ion battery.

[0031] It should be noted that when the first electrode is a positive electrode, the second electrode is a negative electrode; and when the first electrode is a negative electrode, the second electrode is a positive electrode. That is, the laminated battery cell includes alternating positive and negative electrode sheets, with a separator 3 disposed between the positive and negative electrode sheets. Specifically, a separator 3 is disposed between the outermost electrode sheet 2 and the inner electrode sheet 1, and a separator 3 is disposed between adjacent inner electrode sheets 1. The outermost electrode sheet 2 can be either a positive electrode or a negative electrode.

[0032] In one embodiment, the outermost electrode 2 is a positive electrode. In this case, the outermost current collector 21 is a foamed aluminum current collector or a composite aluminum current collector.

[0033] Specifically, when the outermost current collector 21 is a foamed aluminum current collector, the porosity of the foamed aluminum current collector is 20% to 80%, and the resistivity of the foamed aluminum current collector is 2.82×10 -7 Ω·m to 2.82×10 -6Ω·m, and the thickness of the foam aluminum current collector is 10μm to 30μm.

[0034] It is worth noting that if the porosity of the foam aluminum current collector is too large, the strength of the foam aluminum current collector will be insufficient, and the bending of the outermost electrode 2 cannot be effectively suppressed; if the porosity of the foam aluminum current collector is too small, the resistivity of the foam aluminum current collector will be too small, and the lithium plating problem cannot be improved.

[0035] When the required internal resistance of the outermost current collector 21 is certain, if the resistivity of the foam aluminum current collector is too large, the thickness of the foam aluminum current collector will be too small, and the bending of the outermost electrode 2 cannot be effectively suppressed; if the resistivity of the foam aluminum current collector is too small, the thickness of the foam aluminum current collector will be too large, resulting in the overall size of the laminated battery cell being too large.

[0036] If the thickness of the foamed aluminum current collector is too large, the overall size of the laminated battery core will be too large; if the thickness of the foamed aluminum current collector is too small, the bending of the outermost electrode 2 will not be effectively suppressed.

[0037] In summary, by comprehensively controlling the porosity, resistivity and thickness of the foam aluminum current collector, the bending resistance of the outermost electrode 2 can be effectively improved, while the overall size of the laminated battery cell can be controlled and the lithium plating problem can be effectively improved.

[0038] Optionally, the porosity of the foam aluminum current collector can be any value among 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, etc., or a value between any two values.

[0039] Optionally, the resistivity of the aluminum foam current collector is 2.82×10 -7 Ω·m、3.0×10 -7 Ω·m、5.0×10 -7 Ω·m、7.0×10 -7 Ω·m、9.0×10 -7 Ω·m、1.1×10 -6 Ω·m、2.82×10 -6 Any value in Ω·m, etc. or a value between any two values.

[0040] Optionally, the thickness of the foam aluminum current collector is any value among 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, 25 μm, 28 μm, 30 μm, etc., or a value between any two values.

[0041] Specifically, when the outermost current collector 21 is a composite aluminum current collector, the composite aluminum current collector includes a first bonding layer and aluminum layers arranged on two opposite sides of the first bonding layer. The thickness of the composite aluminum current collector is 5 μm to 30 μm, and the thickness of the aluminum layer is 0.5 μm to 5 μm.

[0042] It is worth noting that if the composite aluminum current collector is too thick, the overall size of the laminated cell will be too large; if the composite aluminum current collector is too thin, it will not be able to effectively prevent the bending of the outermost electrode 2. If the thickness of the aluminum layer is too thin, the composite aluminum current collector will be insufficiently strong and will not be able to effectively prevent the bending of the outermost electrode 2; if the thickness of the aluminum layer is too thick, the resistance of the outermost current collector 21 will be too low, and the lithium plating problem will not be effectively improved.

[0043] Optionally, the thickness of the composite aluminum current collector is any value among 5 μm, 8 μm, 10 μm, 15 μm, 18 μm, 20 μm, 25 μm, 28 μm, 30 μm, etc., or a value between any two values.

[0044] Optionally, the thickness of the aluminum layer is any value among 0.5 μm, 0.8 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, etc., or a value between any two values.

[0045] It should be noted that the first adhesive layer is a polymer adhesive layer, which can be made of PP (polypropylene), PE (polyethylene) or PET (polyethylene terephthalate). The first adhesive layer plays a supporting role for the aluminum layer.

[0046] In one embodiment, the outermost electrode sheet 2 is a negative electrode sheet. In this case, the outermost current collector 21 is a foam copper current collector or a composite copper current collector.

[0047] Specifically, when the outermost current collector 21 is a foam copper current collector, the porosity of the foam copper current collector is 20% to 80%, and the resistivity of the foam copper current collector is 6.75×10 -7 Ω·m to 6.75×10 -6 Ω·m, and the thickness of the foam copper current collector is 5μm to 30μm.

[0048] It is worth noting that if the porosity of the foam copper collector is too large, the strength of the foam copper collector will be insufficient, and the bending of the outermost electrode 2 cannot be effectively suppressed; if the porosity of the foam copper collector is too small, the resistivity of the foam copper collector will be too small, and the lithium plating problem cannot be improved.

[0049] When the required internal resistance of the outermost current collector 21 is certain, if the resistivity of the foam copper current collector is too large, the thickness of the foam copper current collector will be too small, and the bending of the outermost electrode 2 cannot be effectively suppressed; if the resistivity of the foam copper current collector is too small, the thickness of the foam copper current collector will be too large, resulting in the overall size of the laminated battery cell being too large.

[0050] If the thickness of the copper foam current collector is too large, the overall size of the laminated core will be too large; if the thickness of the copper foam current collector is too small, the bending of the outermost electrode 2 will not be effectively suppressed.

[0051] In summary, by comprehensively controlling the porosity, resistivity and thickness of the foam copper current collector, the bending resistance of the outermost electrode 2 can be effectively improved, while the overall size of the laminated battery cell can be controlled and the lithium plating problem can be effectively improved.

[0052] Optionally, the porosity of the foam copper current collector can be any value among 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, etc., or a value between any two values.

[0053] Optionally, the resistivity of the copper foam current collector is 6.75×10 -7 Ω·m、8.0×10 -7 Ω·m、1.0×10 -6 Ω·m、3.0×10 -6 Ω·m、5.0×10 -6 Ω·m、6.75×10 -6 Any value in Ω·m, etc. or a value between any two values.

[0054] Optionally, the thickness of the foam copper current collector is any value among 5 μm, 8 μm, 10 μm, 15 μm, 18 μm, 20 μm, 25 μm, 28 μm, 30 μm, etc., or a value between any two values.

[0055] Specifically, when the outermost current collector 21 is a composite copper current collector, the composite copper current collector includes a second bonding layer and copper layers arranged on two opposite sides of the second bonding layer. The thickness of the composite copper current collector is 5 μm to 30 μm, and the thickness of the copper layer is 0.5 μm to 3 μm.

[0056] It is worth noting that if the thickness of the composite copper current collector is too large, the overall size of the laminated cell will be too large; if the thickness of the composite copper current collector is too small, it will not be able to effectively suppress the bending of the outermost electrode 2. If the thickness of the copper layer is too small, the strength of the composite copper current collector will be insufficient, and the bending of the outermost electrode 2 will not be effectively suppressed; if the thickness of the copper layer is too large, the resistance of the outermost current collector 21 will be too low, and the lithium plating problem will not be effectively improved.

[0057] Optionally, the thickness of the composite copper current collector is any value among 5 μm, 8 μm, 10 μm, 15 μm, 18 μm, 20 μm, 25 μm, 28 μm, 30 μm, etc., or a value between any two values.

[0058] Optionally, the thickness of the copper layer is any value among 0.5 μm, 0.8 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, etc., or a value between any two values.

[0059] It should be noted that the second adhesive layer is a polymer adhesive layer, which can be made of PP (polypropylene), PE (polyethylene) or PET (polyethylene terephthalate). The second adhesive layer plays a supporting role for the copper layer.

[0060] In one embodiment, Figure 2 As shown, the inner electrode 1 includes an inner current collector 11 and an inner active material layer 12 provided on at least one side surface of the inner current collector 11; the thickness of the outermost current collector 21 is H1, the thickness of the inner current collector 11 is H2, the resistivity of the outermost current collector 21 is ρ1, and the resistivity of the inner current collector 11 is ρ2, satisfying: ρ1 / ρ2≥H1 / H2; wherein, the units of H1 and H2 are μm, the units of ρ1 and ρ2 are Ω·m, the value range of H1 is 10μm to 30μm, the value range of H2 is 5μm to 15μm, and the value range of ρ1 is 6.75×10 -7 Ω·m to 2.82×10 -6 Ω·m, the value range of ρ2 is 6.75×10 -8 Ω·m to 2.82×10 -6 This arrangement effectively suppresses the bending of the outermost electrode 2 and solves the problem of lithium deposition at the outermost negative electrode or the negative electrode corresponding to the outermost positive electrode in the laminated battery cell.

[0061] Furthermore, when the inner electrode sheet 1 is a positive electrode sheet, the inner current collector 11 can be an aluminum foil current collector, a foamed aluminum current collector, or a composite aluminum current collector, and the material of the inner active material layer 12 can include one or a mixture of lithium cobalt oxide, a ternary material, lithium iron phosphate, and lithium manganese iron phosphate. When the inner electrode sheet 1 is a negative electrode sheet, the inner current collector 11 can be a copper foil current collector, a foamed copper current collector, or a composite copper current collector, and the material of the inner active material layer 12 can be one or a mixture of graphite, hard carbon, silicon carbon, silicon oxide, pure silicon, and lithium titanate.

[0062] It should be noted that the inner active material layer 12 is disposed corresponding to only one side of the inner current collector 11 , or the inner active material layer 12 is disposed corresponding to two opposite sides of the inner current collector 11 .

[0063] Optionally, the thickness H1 of the outermost current collector 21 is any value among 10 μm, 15 μm, 18 μm, 20 μm, 25 μm, 28 μm, 30 μm, etc., or a value between any two values.

[0064] Optionally, the thickness H2 of the inner current collector 11 is any value among 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, etc., or a value between any two values.

[0065] Optionally, the resistivity ρ1 of the outermost current collector 21 is 6.75×10 -7 Ω·m、8.0×10 -7 Ω·m、9.0×10 -7 Ω·m、1.0×10 -6 Ω·m、2.0×10 -6 Ω·m、2.82×10 -6 Any value in Ω·m, etc. or a value between any two values.

[0066] Optionally, the resistivity ρ2 of the inner current collector 11 is 6.75×10 -8 Ω·m、8.0×10 -8 Ω·m、9.0×10 -8 Ω·m、1.0×10 -7 Ω·m、2.0×10 -7 Ω·m、2.82×10 -7 Ω·m、6.75×10 -7 Ω·m、8.0×10 -7 Ω·m、9.0×10 -7 Ω·m、1.0×10 -6 Ω·m、2.0×10 -6 Ω·m、2.82×10 -6 Any value in Ω·m, etc. or a value between any two values.

[0067] In one embodiment, the thickness of the outermost active material layer 22 is 15 μm to 150 μm. Specifically, when the outermost electrode sheet 2 is a positive electrode sheet, the outermost active material layer 22 is a positive electrode active material layer, and the thickness of the positive electrode active material layer is 15 μm to 150 μm; when the outermost electrode sheet 2 is a negative electrode sheet, the outermost active material layer 22 is a negative electrode active material layer, and the thickness of the negative electrode active material layer is 15 μm to 150 μm.

[0068] Optionally, the thickness of the outermost active material layer 22 is any value among 15μm, 20μm, 25μm, 28μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, etc., or a value between any two values.

[0069] According to an embodiment of the present invention, on the other hand, a secondary battery is provided, comprising the above-mentioned laminated battery cell.

[0070] It should be noted that the secondary battery is a lithium-ion secondary battery, which includes a laminated cell, an electrolyte and an aluminum-plastic film. The laminated cell includes a cell body and positive and negative electrode tabs extending from the cell body, and the cell body is encapsulated in the aluminum-plastic film.

[0071] The present application is further described in detail below with reference to specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in this application.

[0072] Example 1

[0073] (1) Lithium cobalt oxide is used as the positive electrode active material to prepare the positive electrode slurry: the positive electrode slurry is prepared according to a certain batching process according to the ratio of 96% positive electrode active material, 2.5% conductive agent, and 1.5% binder. The slurry viscosity is 2000-7000 mPa·s and the solid content is 70%-80%.

[0074] (2) Preparation of negative electrode slurry using graphite as the negative electrode active material: The negative electrode slurry is prepared according to a certain batching process according to the ratio of 96.8% negative electrode active material, 1.2% conductive agent, and 2% binder. The slurry viscosity is 2000-5000 mPa·s and the solid content is 40%-50%.

[0075] (3) The positive electrode slurry prepared by (1) was coated on a foamed aluminum current collector. The foamed aluminum current collector had a thickness of 20 μm, a porosity of 20%, and a resistivity of 2.82×10 -7 Ω·m, and dried to obtain the outermost positive electrode sheet.

[0076] (4) The positive electrode slurry prepared by (1) is coated on an aluminum foil current collector having a thickness of 10 μm, and dried to obtain an inner positive electrode sheet.

[0077] (5) The negative electrode slurry prepared in (2) is coated on a copper foil current collector having a thickness of 10 μm, and dried to obtain an inner negative electrode sheet.

[0078] (6) The positive and negative electrode sheets obtained above are rolled, die-cut and slit, and then stacked to form a laminated battery cell. After passing the short-circuit test, they are packaged with aluminum-plastic film and baked in an oven to remove moisture. After the moisture reaches the moisture standard required for liquid injection, the electrolyte is injected. After aging for 24h-48h, the first charge is completed by a hot pressing process to obtain an activated battery.

[0079] Example 2

[0080] (1) Lithium cobalt oxide is used as the positive electrode active material to prepare the positive electrode slurry: the positive electrode slurry is prepared according to a certain batching process according to the ratio of 96% positive electrode active material, 2.5% conductive agent, and 1.5% binder. The slurry viscosity is 2000-7000 mPa·s and the solid content is 70%-80%.

[0081] (2) Preparation of negative electrode slurry using graphite as the negative electrode active material: The negative electrode slurry is prepared according to a certain batching process according to the ratio of 96.8% negative electrode active material, 1.2% conductive agent, and 2% binder. The slurry viscosity is 2000-5000 mPa·s and the solid content is 40%-50%.

[0082] (3) The positive electrode slurry prepared by (1) was coated on a foamed aluminum current collector. The foamed aluminum current collector had a thickness of 30 μm, a porosity of 80%, and a resistivity of 2.82×10 -6 Ω·m, and dried to obtain the outermost positive electrode sheet.

[0083] (4) The positive electrode slurry prepared by (1) is coated on an aluminum foil current collector having a thickness of 10 μm, and dried to obtain an inner positive electrode sheet.

[0084] (5) The negative electrode slurry prepared in (2) is coated on a copper foil current collector having a thickness of 10 μm, and dried to obtain an inner negative electrode sheet.

[0085] (6) The positive and negative electrode sheets obtained above are rolled, die-cut and slit, and then stacked to form a laminated battery cell. After passing the short-circuit test, they are packaged with aluminum-plastic film and baked in an oven to remove moisture. After the moisture reaches the moisture standard required for liquid injection, the electrolyte is injected. After aging for 24h-48h, the first charge is completed by a hot pressing process to obtain an activated battery.

[0086] Example 3

[0087] (1) Lithium cobalt oxide is used as the positive electrode active material to prepare the positive electrode slurry: the positive electrode slurry is prepared according to a certain batching process according to the ratio of 96% positive electrode active material, 2.5% conductive agent, and 1.5% binder. The slurry viscosity is 2000-7000 mPa·s and the solid content is 70%-80%.

[0088] (2) Preparation of negative electrode slurry using graphite as the negative electrode active material: The negative electrode slurry is prepared according to a certain batching process according to the ratio of 96.8% negative electrode active material, 1.2% conductive agent, and 2% binder. The slurry viscosity is 2000-5000 mPa·s and the solid content is 40%-50%.

[0089] (3) The positive electrode slurry prepared by (1) was coated on a foamed aluminum current collector. The foamed aluminum current collector had a thickness of 20 μm, a porosity of 50%, and a resistivity of 6.50×10 -6 Ω·m, and dried to obtain the outermost positive electrode sheet.

[0090] (4) The positive electrode slurry prepared by (1) was coated on a foamed aluminum current collector. The foamed aluminum current collector had a thickness of 10 μm, a porosity of 20%, and a resistivity of 2.82×10 -7 Ω·m, and dried to obtain the inner positive electrode sheet.

[0091] (5) The negative electrode slurry prepared in (2) is coated on a copper foil current collector having a thickness of 10 μm, and dried to obtain an inner negative electrode sheet.

[0092] (6) The positive and negative electrode sheets obtained above are rolled, die-cut and slit, and then stacked to form a laminated battery cell. After passing the short-circuit test, they are packaged with aluminum-plastic film and baked in an oven to remove moisture. After the moisture reaches the moisture standard required for liquid injection, the electrolyte is injected. After aging for 24h-48h, the first charge is completed by a hot pressing process to obtain an activated battery.

[0093] Example 4

[0094] (1) Lithium cobalt oxide is used as the positive electrode active material to prepare the positive electrode slurry: the positive electrode slurry is prepared according to a certain batching process according to the ratio of 96% positive electrode active material, 2.5% conductive agent, and 1.5% binder. The slurry viscosity is 2000-7000 mPa·s and the solid content is 70%-80%.

[0095] (2) Preparation of negative electrode slurry using graphite as the negative electrode active material: The negative electrode slurry is prepared according to a certain batching process according to the ratio of 96.8% negative electrode active material, 1.2% conductive agent, and 2% binder. The slurry viscosity is 2000-5000 mPa·s and the solid content is 40%-50%.

[0096] (3) The positive electrode slurry prepared by (1) is coated on an aluminum foil current collector having a thickness of 10 μm, and dried to obtain an inner positive electrode sheet.

[0097] (4) The negative electrode slurry prepared by (2) was coated on a foam copper current collector. The foam copper current collector had a thickness of 15 μm, a porosity of 20%, and a resistivity of 6.75×10 -7 Ω·m, and dried to obtain the outermost negative electrode sheet.

[0098] (5) The negative electrode slurry prepared in (2) is coated on a copper foil current collector having a thickness of 6 μm, and dried to obtain an inner negative electrode sheet.

[0099] (6) The positive and negative electrode sheets obtained above are rolled, die-cut and slit, and then stacked to form a laminated battery cell. After passing the short-circuit test, they are packaged with aluminum-plastic film and baked in an oven to remove moisture. After the moisture reaches the moisture standard required for liquid injection, the electrolyte is injected. After aging for 24h-48h, the first charge is completed by a hot pressing process to obtain an activated battery.

[0100] Example 5

[0101] (1) Lithium cobalt oxide is used as the positive electrode active material to prepare the positive electrode slurry: the positive electrode slurry is prepared according to a certain batching process according to the ratio of 96% positive electrode active material, 2.5% conductive agent, and 1.5% binder. The slurry viscosity is 2000-7000 mPa·s and the solid content is 70%-80%.

[0102] (2) Preparation of negative electrode slurry using graphite as the negative electrode active material: The negative electrode slurry is prepared according to a certain batching process according to the ratio of 96.8% negative electrode active material, 1.2% conductive agent, and 2% binder. The slurry viscosity is 2000-5000 mPa·s and the solid content is 40%-50%.

[0103] (3) The positive electrode slurry prepared by (1) is coated on an aluminum foil current collector having a thickness of 10 μm, and dried to obtain an inner positive electrode sheet.

[0104] (4) The negative electrode slurry prepared by (2) was coated on a foam copper current collector. The foam copper current collector had a thickness of 30 μm, a porosity of 80%, and a resistivity of 6.75×10 -6 Ω·m, and dried to obtain the outermost negative electrode sheet.

[0105] (5) The negative electrode slurry prepared in (2) is coated on a copper foil current collector having a thickness of 6 μm, and dried to obtain an inner negative electrode sheet.

[0106] (6) The positive and negative electrode sheets obtained above are rolled, die-cut and slit, and then stacked to form a laminated battery cell. After passing the short-circuit test, they are packaged with aluminum-plastic film and baked in an oven to remove moisture. After the moisture reaches the moisture standard required for liquid injection, the electrolyte is injected. After aging for 24h-48h, the first charge is completed by a hot pressing process to obtain an activated battery.

[0107] Example 6

[0108] (1) Lithium cobalt oxide is used as the positive electrode active material to prepare the positive electrode slurry: the positive electrode slurry is prepared according to a certain batching process according to the ratio of 96% positive electrode active material, 2.5% conductive agent, and 1.5% binder. The slurry viscosity is 2000-7000 mPa·s and the solid content is 70%-80%.

[0109] (2) Preparation of negative electrode slurry using graphite as the negative electrode active material: The negative electrode slurry is prepared according to a certain batching process according to the ratio of 96.8% negative electrode active material, 1.2% conductive agent, and 2% binder. The slurry viscosity is 2000-5000 mPa·s and the solid content is 40%-50%.

[0110] (3) The positive electrode slurry prepared by (1) is coated on an aluminum foil current collector having a thickness of 10 μm, and dried to obtain an inner positive electrode sheet.

[0111] (4) The negative electrode slurry prepared by (2) was coated on a foam copper current collector. The foam copper current collector had a thickness of 15 μm, a porosity of 50%, and a resistivity of 1.75×10 -6 Ω·m, and dried to obtain the outermost negative electrode sheet.

[0112] (5) The negative electrode slurry prepared in (2) is coated on a copper foil current collector having a thickness of 6 μm, and dried to obtain an inner negative electrode sheet.

[0113] (6) The positive and negative electrode sheets obtained above are rolled, die-cut and slit, and then stacked to form a laminated battery cell. After passing the short-circuit test, they are packaged with aluminum-plastic film and baked in an oven to remove moisture. After the moisture reaches the moisture standard required for liquid injection, the electrolyte is injected. After aging for 24h-48h, the first charge is completed by a hot pressing process to obtain an activated battery.

[0114] Example 7

[0115] (1) Lithium cobalt oxide is used as the positive electrode active material to prepare the positive electrode slurry: the positive electrode slurry is prepared according to a certain batching process according to the ratio of 96% positive electrode active material, 2.5% conductive agent, and 1.5% binder. The slurry viscosity is 2000-7000 mPa·s and the solid content is 70%-80%.

[0116] (2) Preparation of negative electrode slurry using graphite as the negative electrode active material: The negative electrode slurry is prepared according to a certain batching process according to the ratio of 96.8% negative electrode active material, 1.2% conductive agent, and 2% binder. The slurry viscosity is 2000-5000 mPa·s and the solid content is 40%-50%.

[0117] (3) The positive electrode slurry prepared by (1) is coated on a composite aluminum current collector, the thickness of the composite aluminum current collector is 20 μm, the thickness of the aluminum layer is 3 μm, and dried to obtain the outermost positive electrode sheet.

[0118] (4) The positive electrode slurry prepared by (1) is coated on an aluminum foil current collector having a thickness of 10 μm, and dried to obtain an inner positive electrode sheet.

[0119] (5) The negative electrode slurry prepared in (2) is coated on a copper foil current collector having a thickness of 10 μm, and dried to obtain an inner negative electrode sheet.

[0120] (6) The positive and negative electrode sheets obtained above are rolled, die-cut and slit, and then stacked to form a laminated battery cell. After passing the short-circuit test, they are packaged with aluminum-plastic film and baked in an oven to remove moisture. After the moisture reaches the moisture standard required for liquid injection, the electrolyte is injected. After aging for 24h-48h, the first charge is completed by a hot pressing process to obtain an activated battery.

[0121] Example 8

[0122] (1) Lithium cobalt oxide is used as the positive electrode active material to prepare the positive electrode slurry: the positive electrode slurry is prepared according to a certain batching process according to the ratio of 96% positive electrode active material, 2.5% conductive agent, and 1.5% binder. The slurry viscosity is 2000-7000 mPa·s and the solid content is 70%-80%.

[0123] (2) Preparation of negative electrode slurry using graphite as the negative electrode active material: The negative electrode slurry is prepared according to a certain batching process according to the ratio of 96.8% negative electrode active material, 1.2% conductive agent, and 2% binder. The slurry viscosity is 2000-5000 mPa·s and the solid content is 40%-50%.

[0124] (3) The positive electrode slurry prepared by (1) is coated on a composite aluminum current collector, the thickness of the composite aluminum current collector is 20 μm, the thickness of the aluminum layer is 1 μm, and dried to obtain the outermost positive electrode sheet.

[0125] (4) The positive electrode slurry prepared by (1) is coated on an aluminum foil current collector having a thickness of 10 μm, and dried to obtain an inner positive electrode sheet.

[0126] (5) The negative electrode slurry prepared in (2) is coated on a copper foil current collector having a thickness of 10 μm, and dried to obtain an inner negative electrode sheet.

[0127] (6) The positive and negative electrode sheets obtained above are rolled, die-cut and slit, and then stacked to form a laminated battery cell. After passing the short-circuit test, they are packaged with aluminum-plastic film and baked in an oven to remove moisture. After the moisture reaches the moisture standard required for liquid injection, the electrolyte is injected. After aging for 24h-48h, the first charge is completed by a hot pressing process to obtain an activated battery.

[0128] Example 9

[0129] (1) Lithium cobalt oxide is used as the positive electrode active material to prepare the positive electrode slurry: the positive electrode slurry is prepared according to a certain batching process according to the ratio of 96% positive electrode active material, 2.5% conductive agent, and 1.5% binder. The slurry viscosity is 2000-7000 mPa·s and the solid content is 70%-80%.

[0130] (2) Preparation of negative electrode slurry using graphite as the negative electrode active material: The negative electrode slurry is prepared according to a certain batching process according to the ratio of 96.8% negative electrode active material, 1.2% conductive agent, and 2% binder. The slurry viscosity is 2000-5000 mPa·s and the solid content is 40%-50%.

[0131] (3) The positive electrode slurry prepared by (1) is coated on a composite aluminum current collector, the thickness of the composite aluminum current collector is 20 μm, the thickness of the aluminum layer is 5 μm, and dried to obtain the outermost positive electrode sheet.

[0132] (4) The positive electrode slurry prepared by (1) is coated on an aluminum foil current collector having a thickness of 10 μm, and dried to obtain an inner positive electrode sheet.

[0133] (5) The negative electrode slurry prepared in (2) is coated on a copper foil current collector having a thickness of 10 μm, and dried to obtain an inner negative electrode sheet.

[0134] (6) The positive and negative electrode sheets obtained above are rolled, die-cut and slit, and then stacked to form a laminated battery cell. After passing the short-circuit test, they are packaged with aluminum-plastic film and baked in an oven to remove moisture. After the moisture reaches the moisture standard required for liquid injection, the electrolyte is injected. After aging for 24h-48h, the first charge is completed by a hot pressing process to obtain an activated battery.

[0135] Example 10

[0136] (1) Lithium cobalt oxide is used as the positive electrode active material to prepare the positive electrode slurry: the positive electrode slurry is prepared according to a certain batching process according to the ratio of 96% positive electrode active material, 2.5% conductive agent, and 1.5% binder. The slurry viscosity is 2000-7000 mPa·s and the solid content is 70%-80%.

[0137] (2) Preparation of negative electrode slurry using graphite as the negative electrode active material: The negative electrode slurry is prepared according to a certain batching process according to the ratio of 96.8% negative electrode active material, 1.2% conductive agent, and 2% binder. The slurry viscosity is 2000-5000 mPa·s and the solid content is 40%-50%.

[0138] (3) The positive electrode slurry prepared by (1) is coated on an aluminum foil current collector having a thickness of 10 μm, and dried to obtain an inner positive electrode sheet.

[0139] (4) The negative electrode slurry prepared by (2) is coated on a composite copper current collector, the thickness of the composite copper current collector is 15 μm, the thickness of the copper layer is 2 μm, and the mixture is dried to obtain an outermost negative electrode sheet.

[0140] (5) The negative electrode slurry prepared in (2) is coated on a copper foil current collector having a thickness of 6 μm, and dried to obtain an inner negative electrode sheet.

[0141] (6) The positive and negative electrode sheets obtained above are rolled, die-cut and slit, and then stacked to form a laminated battery cell. After passing the short-circuit test, they are packaged with aluminum-plastic film and baked in an oven to remove moisture. After the moisture reaches the moisture standard required for liquid injection, the electrolyte is injected. After aging for 24h-48h, the first charge is completed by a hot pressing process to obtain an activated battery.

[0142] Example 11

[0143] (1) Lithium cobalt oxide is used as the positive electrode active material to prepare the positive electrode slurry: the positive electrode slurry is prepared according to a certain batching process according to the ratio of 96% positive electrode active material, 2.5% conductive agent, and 1.5% binder. The slurry viscosity is 2000-7000 mPa·s and the solid content is 70%-80%.

[0144] (2) Preparation of negative electrode slurry using graphite as the negative electrode active material: The negative electrode slurry is prepared according to a certain batching process according to the ratio of 96.8% negative electrode active material, 1.2% conductive agent, and 2% binder. The slurry viscosity is 2000-5000 mPa·s and the solid content is 40%-50%.

[0145] (3) The positive electrode slurry prepared by (1) is coated on an aluminum foil current collector having a thickness of 10 μm, and dried to obtain an inner positive electrode sheet.

[0146] (4) The negative electrode slurry prepared by (2) is coated on a composite copper current collector, the thickness of the composite copper current collector is 15 μm, the thickness of the copper layer is 1 μm, and dried to obtain the outermost negative electrode sheet.

[0147] (5) The negative electrode slurry prepared in (2) is coated on a copper foil current collector having a thickness of 6 μm, and dried to obtain an inner negative electrode sheet.

[0148] (6) The positive and negative electrode sheets obtained above are rolled, die-cut and slit, and then stacked to form a laminated battery cell. After passing the short-circuit test, they are packaged with aluminum-plastic film and baked in an oven to remove moisture. After the moisture reaches the moisture standard required for liquid injection, the electrolyte is injected. After aging for 24h-48h, the first charge is completed by a hot pressing process to obtain an activated battery.

[0149] Example 12

[0150] (1) Lithium cobalt oxide is used as the positive electrode active material to prepare the positive electrode slurry: the positive electrode slurry is prepared according to a certain batching process according to the ratio of 96% positive electrode active material, 2.5% conductive agent, and 1.5% binder. The slurry viscosity is 2000-7000 mPa·s and the solid content is 70%-80%.

[0151] (2) Preparation of negative electrode slurry using graphite as the negative electrode active material: The negative electrode slurry is prepared according to a certain batching process according to the ratio of 96.8% negative electrode active material, 1.2% conductive agent, and 2% binder. The slurry viscosity is 2000-5000 mPa·s and the solid content is 40%-50%.

[0152] (3) The positive electrode slurry prepared by (1) is coated on an aluminum foil current collector having a thickness of 10 μm, and dried to obtain an inner positive electrode sheet.

[0153] (4) The negative electrode slurry prepared by (2) is coated on a composite copper current collector, the thickness of the composite copper current collector is 15 μm, the thickness of the copper layer is 3 μm, and dried to obtain the outermost negative electrode sheet.

[0154] (5) The negative electrode slurry prepared in (2) is coated on a copper foil current collector having a thickness of 6 μm, and dried to obtain an inner negative electrode sheet.

[0155] (6) The positive and negative electrode sheets obtained above are rolled, die-cut and slit, and then stacked to form a laminated battery cell. After passing the short-circuit test, they are packaged with aluminum-plastic film and baked in an oven to remove moisture. After the moisture reaches the moisture standard required for liquid injection, the electrolyte is injected. After aging for 24h-48h, the first charge is completed by a hot pressing process to obtain an activated battery.

[0156] Example 13

[0157] (1) Lithium cobalt oxide is used as the positive electrode active material to prepare the positive electrode slurry: the positive electrode slurry is prepared according to a certain batching process according to the ratio of 96% positive electrode active material, 2.5% conductive agent, and 1.5% binder. The slurry viscosity is 2000-7000 mPa·s and the solid content is 70%-80%.

[0158] (2) Preparation of negative electrode slurry using graphite as the negative electrode active material: The negative electrode slurry is prepared according to a certain batching process according to the ratio of 96.8% negative electrode active material, 1.2% conductive agent, and 2% binder. The slurry viscosity is 2000-5000 mPa·s and the solid content is 40%-50%.

[0159] (3) The positive electrode slurry prepared by (1) was coated on a foamed aluminum current collector. The foamed aluminum current collector had a thickness of 20 μm, a porosity of 20%, and a resistivity of 2.82×10 -7 Ω·m, and dried to obtain the outermost positive electrode sheet.

[0160] (4) The positive electrode slurry prepared by (1) is coated on a composite aluminum current collector, the thickness of the composite aluminum current collector is 10 μm, the thickness of the aluminum layer is 3 μm, and the mixture is dried to obtain an inner positive electrode sheet.

[0161] (5) The negative electrode slurry prepared in (2) is coated on a copper foil current collector having a thickness of 10 μm, and dried to obtain an inner negative electrode sheet.

[0162] (6) The positive and negative electrode sheets obtained above are rolled, die-cut and slit, and then stacked to form a laminated battery cell. After passing the short-circuit test, they are packaged with aluminum-plastic film and baked in an oven to remove moisture. After the moisture reaches the moisture standard required for liquid injection, the electrolyte is injected. After aging for 24h-48h, the first charge is completed by a hot pressing process to obtain an activated battery.

[0163] Example 14

[0164] (1) Lithium cobalt oxide is used as the positive electrode active material to prepare the positive electrode slurry: the positive electrode slurry is prepared according to a certain batching process according to the ratio of 96% positive electrode active material, 2.5% conductive agent, and 1.5% binder. The slurry viscosity is 2000-7000 mPa·s and the solid content is 70%-80%.

[0165] (2) Preparation of negative electrode slurry using graphite as the negative electrode active material: The negative electrode slurry is prepared according to a certain batching process according to the ratio of 96.8% negative electrode active material, 1.2% conductive agent, and 2% binder. The slurry viscosity is 2000-5000 mPa·s and the solid content is 40%-50%.

[0166] (3) The positive electrode slurry prepared by (1) is coated on an aluminum foil current collector having a thickness of 10 μm, and dried to obtain an inner positive electrode sheet.

[0167] (4) The negative electrode slurry prepared by (2) was coated on a foam copper current collector. The foam copper current collector had a thickness of 30 μm, a porosity of 80%, and a resistivity of 6.75×10 -6 Ω·m, and dried to obtain the outermost negative electrode sheet.

[0168] (5) The negative electrode slurry prepared by (2) is coated on a composite copper current collector, the thickness of the composite copper current collector is 10 μm, the thickness of the copper layer is 3 μm, and dried to obtain an inner layer negative electrode sheet.

[0169] (6) The positive and negative electrode sheets obtained above are rolled, die-cut and slit, and then stacked to form a laminated battery cell. After passing the short-circuit test, they are packaged with aluminum-plastic film and baked in an oven to remove moisture. After the moisture reaches the moisture standard required for liquid injection, the electrolyte is injected. After aging for 24h-48h, the first charge is completed by a hot pressing process to obtain an activated battery.

[0170] In order to conduct a comparative analysis of the lithium plating conditions of the batteries, the comparative battery is described in detail below.

[0171] Comparative Example 1

[0172] (1) Lithium cobalt oxide is used as the positive electrode active material to prepare the positive electrode slurry: the positive electrode slurry is prepared according to a certain batching process according to the ratio of 96% positive electrode active material, 2.5% conductive agent, and 1.5% binder. The slurry viscosity is 2000-7000 mPa·s and the solid content is 70%-80%.

[0173] (2) Preparation of negative electrode slurry using graphite as the negative electrode active material: The negative electrode slurry is prepared according to a certain batching process according to the ratio of 96.8% negative electrode active material, 1.2% conductive agent, and 2% binder. The slurry viscosity is 2000-5000 mPa·s and the solid content is 40%-50%.

[0174] (3) The positive electrode slurry prepared by (1) was coated on a foamed aluminum current collector. The foamed aluminum current collector had a thickness of 20 μm, a porosity of 20%, and a resistivity of 2.82×10 -7 Ω·m, and dried to obtain the outermost positive electrode sheet.

[0175] (4) The positive electrode slurry prepared by (1) was coated on the foam aluminum current collector. The foam aluminum current collector had a thickness of 10 μm, a porosity of 80%, and a resistivity of 2.82×10 -6Ω·m, and dried to obtain the inner positive electrode sheet.

[0176] (5) The negative electrode slurry prepared in (2) is coated on a copper foil current collector having a thickness of 10 μm, and dried to obtain an inner negative electrode sheet.

[0177] (6) The positive and negative electrode sheets obtained above are rolled, die-cut and slit, and then stacked to form a laminated battery cell. After passing the short-circuit test, they are packaged with aluminum-plastic film and baked in an oven to remove moisture. After the moisture reaches the moisture standard required for liquid injection, the electrolyte is injected. After aging for 24h-48h, the first charge is completed by a hot pressing process to obtain an activated battery.

[0178] Comparative Example 2

[0179] (1) Lithium cobalt oxide is used as the positive electrode active material to prepare the positive electrode slurry: the positive electrode slurry is prepared according to a certain batching process according to the ratio of 96% positive electrode active material, 2.5% conductive agent, and 1.5% binder. The slurry viscosity is 2000-7000 mPa·s and the solid content is 70%-80%.

[0180] (2) Preparation of negative electrode slurry using graphite as the negative electrode active material: The negative electrode slurry is prepared according to a certain batching process according to the ratio of 96.8% negative electrode active material, 1.2% conductive agent, and 2% binder. The slurry viscosity is 2000-5000 mPa·s and the solid content is 40%-50%.

[0181] (3) The positive electrode slurry prepared by (1) is coated on an aluminum foil current collector having a thickness of 10 μm, and dried to obtain an inner positive electrode sheet.

[0182] (4) The negative electrode slurry prepared by (2) was coated on a foam copper current collector. The foam copper current collector had a thickness of 15 μm, a porosity of 20%, and a resistivity of 2.82×10 -7 Ω·m, and dried to obtain the outermost negative electrode sheet.

[0183] (5) The negative electrode slurry prepared in (2) was coated on a foam copper current collector. The foam copper current collector had a thickness of 6 μm, a porosity of 80%, and a resistivity of 6.75×10 -6 Ω·m, and dried to obtain the inner negative electrode sheet.

[0184] (6) The positive and negative electrode sheets obtained above are rolled, die-cut and slit, and then stacked to form a laminated battery cell. After passing the short-circuit test, they are packaged with aluminum-plastic film and baked in an oven to remove moisture. After the moisture reaches the moisture standard required for liquid injection, the electrolyte is injected. After aging for 24h-48h, the first charge is completed by a hot pressing process to obtain an activated battery.

[0185] Comparative Example 3

[0186] (1) Lithium cobalt oxide is used as the positive electrode active material to prepare the positive electrode slurry: the positive electrode slurry is prepared according to a certain batching process according to the ratio of 96% positive electrode active material, 2.5% conductive agent, and 1.5% binder. The slurry viscosity is 2000-7000 mPa·s and the solid content is 70%-80%.

[0187] (2) Preparation of negative electrode slurry using graphite as the negative electrode active material: The negative electrode slurry is prepared according to a certain batching process according to the ratio of 96.8% negative electrode active material, 1.2% conductive agent, and 2% binder. The slurry viscosity is 2000-5000 mPa·s and the solid content is 40%-50%.

[0188] (3) The positive electrode slurry prepared by (1) is coated on a composite aluminum current collector, the thickness of the composite aluminum current collector is 20 μm, the thickness of the aluminum layer is 6 μm, and dried to obtain the outermost positive electrode sheet.

[0189] (4) The positive electrode slurry prepared by (1) is coated on an aluminum foil current collector having a thickness of 10 μm, and dried to obtain an inner positive electrode sheet.

[0190] (5) The negative electrode slurry prepared in (2) is coated on a copper foil current collector having a thickness of 10 μm, and dried to obtain an inner negative electrode sheet.

[0191] (6) The positive and negative electrode sheets obtained above are rolled, die-cut and slit, and then stacked to form a laminated battery cell. After passing the short-circuit test, they are packaged with aluminum-plastic film and baked in an oven to remove moisture. After the moisture reaches the moisture standard required for liquid injection, the electrolyte is injected. After aging for 24h-48h, the first charge is completed by a hot pressing process to obtain an activated battery.

[0192] Comparative Example 4

[0193] (1) Lithium cobalt oxide is used as the positive electrode active material to prepare the positive electrode slurry: the positive electrode slurry is prepared according to a certain batching process according to the ratio of 96% positive electrode active material, 2.5% conductive agent, and 1.5% binder. The slurry viscosity is 2000-7000 mPa·s and the solid content is 70%-80%.

[0194] (2) Preparation of negative electrode slurry using graphite as the negative electrode active material: The negative electrode slurry is prepared according to a certain batching process according to the ratio of 96.8% negative electrode active material, 1.2% conductive agent, and 2% binder. The slurry viscosity is 2000-5000 mPa·s and the solid content is 40%-50%.

[0195] (3) The positive electrode slurry prepared by (1) is coated on an aluminum foil current collector having a thickness of 10 μm, and dried to obtain an inner positive electrode sheet.

[0196] (4) The negative electrode slurry prepared by (2) is coated on a composite copper current collector, the thickness of the composite copper current collector is 15 μm, the thickness of the copper layer is 4 μm, and the mixture is dried to obtain an outermost negative electrode sheet.

[0197] (5) The negative electrode slurry prepared in (2) is coated on a copper foil current collector having a thickness of 6 μm, and dried to obtain an inner negative electrode sheet.

[0198] (6) The positive and negative electrode sheets obtained above are rolled, die-cut and slit, and then stacked to form a laminated battery cell. After passing the short-circuit test, they are packaged with aluminum-plastic film and baked in an oven to remove moisture. After the moisture reaches the moisture standard required for liquid injection, the electrolyte is injected. After aging for 24h-48h, the first charge is completed by a hot pressing process to obtain an activated battery.

[0199] The example batteries of Examples 1 to 14 and the comparative batteries of Comparative Examples 1 to 4 were subjected to a cycle test. Specifically, the batteries were charged at a 3C rate and discharged at a 1C rate for 800 cycles. The batteries were then dissected to observe whether the outermost current collector 21 was curled, and whether lithium deposition occurred on the outermost negative electrode sheet or the negative electrode sheet corresponding to the outermost positive electrode sheet. The test results are shown in Tables 1, 2, and 3.

[0200] Table 1 Test results of example batteries and comparative example batteries (I)

[0201]

[0202] Table 2 Test results of the battery of the embodiment and the comparative example (II)

[0203]

[0204] Table 3 Test results of example batteries and comparative example batteries (III)

[0205]

[0206] In summary, the batteries of Examples 1 to 14 significantly improve the curling of the outermost current collector 21 and the lithium plating of the outermost negative electrode sheet or the negative electrode sheet corresponding to the outermost positive electrode sheet, compared with the batteries of Comparative Examples 1 to 4.

[0207] Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations shall fall within the scope defined by the appended claims.

Claims

1. A laminated battery cell comprising a first pole piece, a diaphragm (3) and a second pole piece stacked in layers, wherein the first pole piece and the second pole piece have opposite polarities, and is characterized in that: The first pole piece includes: Inner pole piece (1); an outermost electrode piece (2) located outside the inner electrode piece (1), the outermost electrode piece (2) comprising an outermost current collector (21) and an outermost active material layer (22) disposed on one side surface of the outermost current collector (21), the outermost active material layer (22) being disposed close to the inner electrode piece (1); Wherein, the outermost current collector (21) is a foam current collector or a composite current collector.

2. The laminated battery cell according to claim 1, characterized in that: The outermost electrode (2) is a positive electrode, and the outermost current collector (21) is a foamed aluminum current collector or a composite aluminum current collector.

3. The laminated battery cell according to claim 2, characterized in that: The porosity of the foamed aluminum current collector is 20% to 80%; and / or, The resistivity of the aluminum foam current collector is 2.82×10 -7 Ω·m to 2.82×10 -6 Ω·m; and / or, The thickness of the foam aluminum current collector is 10 μm to 30 μm.

4. The laminated battery cell according to claim 2, characterized in that: The composite aluminum current collector includes a first bonding layer and aluminum layers disposed on two opposite sides of the first bonding layer. The composite aluminum current collector has a thickness of 5 μm to 30 μm, and the aluminum layer has a thickness of 0.5 μm to 5 μm.

5. The laminated battery cell according to any one of claims 1 to 4, characterized in that: The outermost electrode (2) is a negative electrode, and the outermost current collector (21) is a foam copper current collector or a composite copper current collector.

6. The laminated battery cell according to claim 5, characterized in that: The porosity of the foam copper current collector is 20% to 80%; and / or, The resistivity of the foam copper current collector is 6.75×10 -7 Ω·m to 6.75×10 -6 Ω·m; and / or, The thickness of the foam copper current collector is 5 μm to 30 μm.

7. The laminated battery cell according to claim 5, characterized in that: The composite copper current collector includes a second bonding layer and copper layers disposed on two opposite sides of the second bonding layer. The composite copper current collector has a thickness of 5 μm to 30 μm, and the copper layers have a thickness of 0.5 μm to 3 μm.

8. The laminated battery core according to any one of claims 1 to 4, characterized in that: The inner electrode (1) comprises an inner current collector (11) and an inner active material layer (12) disposed on at least one side surface of the inner current collector (11); The inner electrode sheet (1) is a positive electrode sheet, and the inner current collector (11) is an aluminum foil current collector, or a foamed aluminum current collector, or a composite aluminum current collector; or, the inner electrode sheet (1) is a negative electrode sheet, and the inner current collector (11) is a copper foil current collector, or a foamed copper current collector, or a composite copper current collector; The thickness of the outermost current collector (21) is H1, the thickness of the inner current collector (11) is H2, the resistivity of the outermost current collector (21) is ρ1, and the resistivity of the inner current collector (11) is ρ2, satisfying: ρ1 / ρ2≥H1 / H2; The units of H1 and H2 are μm, the units of ρ1 and ρ2 are Ω·m, the value range of H1 is 10μm to 30μm, the value range of H2 is 5μm to 15μm, and the value range of ρ1 is 6.75×10 -7 Ω·m to 2.82×10 -6 Ω·m, the value range of ρ2 is 6.75×10 -8 Ω·m to 2.82×10 -6 Ω·m.

9. The laminated battery core according to any one of claims 1 to 4, characterized in that: The thickness of the outermost active material layer (22) is 15 μm to 150 μm; and / or, The first electrode is a positive electrode, and the second electrode is a negative electrode; or the first electrode is a negative electrode, and the second electrode is a positive electrode.

10. A secondary battery, characterized in that: A laminated battery core comprising the laminated battery core according to any one of claims 1 to 9.

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