Lithium ion secondary battery

Abstract

The invention provides a lithium ion secondary battery which comprises a positive plate, the positive plate comprises a positive current collector, the positive current collector is provided with N positive tabs, N is greater than or equal to 2, and a positive functional layer comprising a positive active material is arranged on at least part of the functional surface of the positive current collector; the positive electrode active material comprises a single crystal ternary material with the chemical composition of LipMem( NixCoyMnz) O2 and a polycrystal ternary material with the chemical composition of LiqMen (NiaCobMnc) O2, the lithium ion secondary battery meets the condition that (C * N) / W is greater than or equal to 0.2 and less than or equal to 7.5, and C is the nickel molar content of the positive electrode active material; w is the width of the positive pole lug. The lithium ion secondary battery not only has relatively high energy density, but also has relatively good high-temperature cycle performance and safety performance.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery technology and relates to a lithium-ion secondary battery. Background Technology

[0002] In recent years, lithium-ion batteries have been widely used in energy storage systems such as hydropower, wind power, thermal power, and solar power plants, as well as in everyday applications such as power tools, electric bicycles, electric motorcycles, electric vehicles, and aerospace, due to their advantages such as high specific energy, high operating voltage, low self-discharge rate, small size, and light weight. With the continuous expansion of lithium-ion battery applications, the market is placing higher demands on them, such as higher energy density and rate performance, a wider operating temperature range, longer cycle life, and superior safety performance.

[0003] As a crucial component of lithium-ion batteries, the positive electrode active material plays a key role in their electrochemical performance. Common positive electrode materials currently include layered lithium cobalt oxide, spinel, polyanionic materials, and ternary materials. Among these, medium-high nickel (nickel content in the transition metal element is not less than 0.5 molar) ternary materials offer significantly improved energy density compared to other materials, but suffer from lower conductivity. Furthermore, while increasing nickel content contributes to higher energy density, it also significantly increases heat generation during charge and discharge, leading to decreased high-temperature cycling performance and potential safety hazards.

[0004] Therefore, a battery is provided that has high energy density while also having high high-temperature cycle performance and safety performance. Summary of the Invention

[0005] This invention provides a lithium-ion secondary battery that not only has high energy density, but also good high-temperature cycle performance and safety performance.

[0006] This invention provides a lithium-ion secondary battery, the lithium-ion secondary battery comprising a positive electrode sheet; the positive electrode sheet comprising a positive electrode current collector, the positive electrode current collector being provided with N positive electrode tabs, N≥2; a positive electrode functional layer comprising a positive electrode active material is provided on at least a portion of the functional surface of the positive electrode current collector; the positive electrode active material comprising a monocrystalline ternary material and a polycrystalline ternary material;

[0007] The single-crystal ternary material has the chemical composition of Formula 1.

[0008] Li p Me m (Ni x Co y Mn z O2 formula 1

[0009] In Formula 1, 0.9≤p≤1.1, 0.01≤m≤0.5, 0.6≤x≤0.98, 0≤y≤0.4, 0≤z≤0.4, and Me includes at least one of Al, Mg, Zr, B, Y, Sr, W, Ti, Nb, Mo, La, Sb, and Sr.

[0010] The polycrystalline ternary material has the chemical composition of Formula 2.

[0011] Li q Me n (Ni a Co b Mn c O2 formula 2

[0012] In Equation 2, 0.9≤q≤1.1, 0.01≤n≤0.5, 0.6≤a≤0.98, 0≤b≤0.4, 0≤c≤0.4, and Me includes at least one of Al, Mg, Zr, B, Y, Sr, W, Ti, Nb, Mo, La, Sb, and Sr.

[0013] The lithium-ion secondary battery satisfies Equation 3.

[0014] 0.2≤(C×N) / W≤7.5 (Equation 3)

[0015] In Formula 1, C is the molar content of nickel in the positive electrode active material relative to the transition metal elements; W is the width of the positive electrode tab, in mm.

[0016] Furthermore, the width W of the positive electrode tab is 3mm-10mm, and / or the N is 2-60.

[0017] Furthermore, the median particle size Dv50 of the single-crystal ternary material is smaller than the median particle size Dv50 of the polycrystalline ternary material;

[0018] Preferably, the median particle size Dv50 of the single-crystal ternary material is 1μm-8μm, and / or the median particle size Dv50 of the polycrystalline ternary material is 8μm-18μm.

[0019] Furthermore, the primary particles in the polycrystalline ternary material have a particle size of 200nm-800nm, and / or the median particle size Dv50 of the positive electrode active material is 2μm-15μm.

[0020] Furthermore, the positive electrode active material comprises, by mass percentage: 10wt%-90wt% of the single-crystal ternary material and 10wt%-90wt% of the polycrystalline ternary material.

[0021] Furthermore, the positive current collector includes a positive current collector substrate and an epitaxial portion connected to each other. The epitaxial portion is located on one side of the positive current collector substrate and forms the positive electrode tab. At least a portion of the functional surface of the positive current collector substrate is provided with the positive electrode functional layer.

[0022] Furthermore, the lithium-nickel mixing ratio of the single-crystal ternary material is 0.15%-5%, and / or the lithium-nickel mixing ratio of the polycrystalline ternary material is 0.5%-8%.

[0023] Furthermore, the positive electrode functional layer includes an adjacent positive electrode active layer and an inorganic coating, and the inorganic coating is located between the positive electrode active layer and the positive electrode tab;

[0024] Preferably, the width of the inorganic coating is 0.5mm-5mm, and / or the thickness of the inorganic coating is 2μm-25μm;

[0025] Preferably, the inorganic coating includes at least one of boehmite, BaSO4, CaSiO3, CaSiO4, Al2O3, and TiO2.

[0026] Furthermore, the lithium-ion secondary battery satisfies Equation 4 and / or Equation 5.

[0027] 0.2≤(H×D2) / D1≤10 Equation 4

[0028] In Equation 4, H is the thickness of the inorganic coating, D1 is the particle size Dv99 of the single-crystal ternary material, and H≥D1, D2 is the median particle size Dv50 of the inorganic material;

[0029] 5≤B / A≤300 Equation 5

[0030] In Equation 5, A is the projected area of ​​the inorganic coating on the positive current collector, and B is the area of ​​the positive electrode sheet.

[0031] Preferably, the particle size Dv99 of the single-crystal ternary material is 6μm-12μm, and / or the median particle size Dv50 of the inorganic material is 0.2μm-4μm.

[0032] Furthermore, the lithium-ion secondary battery also includes a separator, the separator comprising a substrate and a coating layer, the coating layer comprising a polymer layer and / or a ceramic layer;

[0033] Preferably, the thickness of the substrate is 3μm-8μm, and / or the thickness of the coating layer is 1μm-7μm;

[0034] Preferably, the thickness of the polymer layer is 0.5 μm-4 μm, and / or the thickness of the ceramic layer is 0.5 μm-3 μm;

[0035] Preferably, the areal density of the diaphragm is 3 g / m³. 2 -20g / m 2 .

[0036] Furthermore, the lithium-ion secondary battery also includes an electrolyte, which includes nitrile additives;

[0037] Preferably, the electrolyte satisfies formula 6.

[0038] 1≤E / F≤17 Equation 6

[0039] In Formula 6, E is the mass percentage of the nitrile additive in the electrolyte, in wt%; F is the molar content of nickel in the positive electrode active material relative to the transition metal elements.

[0040] Preferably, the mass percentage E of the nitrile additive in the electrolyte is 1wt%-10wt%.

[0041] Preferably, the nitrile additives include succinate, glutaronitrile, adiponitrile, 1,5-dicyanopentane, 1,6-dicyanohexane, 1,7-dicyanoheptane, 1,8-dicyanoctane, 1,9-dicyanonane, 1,10-dicyanodecane, 1,12-dicyanodecadecane, tetramethylsuccinate, 2-methylglutaronitrile, 2,4-dimethylglutaronitrile, 2,2,4,4-tetramethylglutaronitrile, 1,4-dicyanopentane, 2,6-dicyanoheptane, 2,7-dicyanoctane, 2,8-dicyanonane, and 1,6-dicyanopentane. 1,2-Dicyanobenzene, 1,3-Dicyanobenzene, 1,4-Dicyanobenzene, 3,5-Dioxa-heptanenitrile, 1,4-Di(cyanoethoxy)butane, ethylene glycol di(2-cyanoethyl) ether, diethylene glycol di(2-cyanoethyl) ether, triethylene glycol di(2-cyanoethyl) ether, tetraethylene glycol di(2-cyanoethyl) ether, 3,6,9,12,15,18-hexaoxaeicosanoic acid dinitrile, 1,3-Di(2-cyanoethoxy)propane, 1,4-Di(2-cyanoethoxy)butane, 1,5-Di(2-cyanoethyl)propane, 1,3-Di(2-cyanoethoxy)butane, 1,4-Di(2-cyanoethyl)propane, 1,5-Di(2-cyanoethyl)propane, 1,4-Di(2-cyanoethoxy)butane, 1,5-Di(2-cyanoethyl)propane, 1,4 ... Ethoxy)pentane, ethylene glycol di(4-cyanobutyl) ether, 1,4-dicyano-2-butene, 1,4-dicyano-2-methyl-2-butene, 1,4-dicyano-2-ethyl-2-butene, 1,4-dicyano-2,3-dimethyl-2-butene, 1,4-dicyano-2,3-diethyl-2-butene, 1,6-dicyano-3-hexene, 1,6-dicyano-2-methyl-3-hexene, 1,6-dicyano-2-methyl-5-methyl-3-hexene, 1,3,5-pentanetricarbonyl, 1,2,3-propanetrimethyl... At least one of the following: nitrile, 1,3,6-hexanetrionitrile, glyceryltrionitrile, 1,2,6-hexanetrionitrile, 1,2,3-tris(2-cyanoethoxy)propane, 1,2,4-tris(2-cyanoethoxy)butane, 1,1,1-tris(cyanoethoxymethylene)ethane, 1,1,1-tris(cyanoethoxymethylene)propane, 3-methyl-1,3,5-tris(cyanoethoxy)pentane, 1,2,7-tris(cyanoethoxy)heptane, 1,2,6-tris(cyanoethoxy)hexane, and 1,2,5-tris(cyanoethoxy)pentane.

[0042] Furthermore, the lithium-ion secondary battery comprises a cell formed by sequentially stacking and winding a positive electrode, a negative electrode, and a separator.

[0043] And / or, the lithium-ion secondary battery includes battery cells stacked in sequence, wherein the battery cell includes a positive electrode, a negative electrode and a separator stacked in sequence.

[0044] This invention improves the high-temperature cycle performance and safety of medium- and high-nickel ternary cathode material system batteries by setting multiple (N≥2) cathode tabs on the cathode current collector and making the cathode active material include both single-crystal ternary material with the chemical composition of Formula 1 and polycrystalline ternary material with the chemical composition of Formula 2. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the positive electrode sheet in one embodiment of the present invention;

[0046] Figure 2 This is a schematic diagram of the positive electrode sheet in another embodiment of the present invention;

[0047] Explanation of reference numerals in the attached figures:

[0048] 1-Positive current collector substrate;

[0049] 2-Extension;

[0050] 3-Positive electrode tab;

[0051] 11-Inorganic coating;

[0052] 12- Positive electrode active layer. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0054] The present invention provides a lithium-ion secondary battery, which includes a positive electrode sheet; the positive electrode sheet includes a positive current collector, the positive current collector is provided with N positive electrode tabs, N≥2; a positive electrode functional layer including a positive electrode active material is provided on at least a portion of the functional surface of the positive current collector; the positive electrode active material includes a monocrystalline ternary material and a polycrystalline ternary material;

[0055] Single-crystal ternary materials have the chemical composition of Formula 1.

[0056] Li p Me m (Ni x Co y Mn z O2 formula 1

[0057] In Formula 1, 0.9≤p≤1.1, 0.01≤m≤0.5, 0.6≤x≤0.98, 0≤y≤0.4, 0≤z≤0.4, and Me includes at least one of Al, Mg, Zr, B, Y, Sr, W, Ti, Nb, Mo, La, Sb, and Sr.

[0058] Polycrystalline ternary materials have the chemical composition of Formula 2.

[0059] Li q Me n (Ni a Co b Mn c O2 formula 2

[0060] In Equation 2, 0.9≤q≤1.1, 0.01≤n≤0.5, 0.6≤a≤0.98, 0≤b≤0.4, 0≤c≤0.4, and Me includes at least one of Al, Mg, Zr, B, Y, Sr, W, Ti, Nb, Mo, La, Sb, and Sr.

[0061] Lithium-ion secondary batteries satisfy Equation 3.

[0062] 0.2≤(C×N) / W≤7.5 (Equation 3)

[0063] In Equation 3, C is the molar content of nickel in the positive electrode active material relative to the transition metal elements; W is the width of the positive electrode tab, in mm.

[0064] The transition metal elements in this invention refer to Ni, Co, and Mn.

[0065] This invention significantly improves the high-temperature cycle performance and safety of medium- and high-nickel ternary cathode material systems for lithium-ion secondary batteries by setting multiple (at least two) cathode tabs on the cathode current collector and including single-crystal ternary materials with the chemical composition of Formula 1 and polycrystalline ternary materials with the chemical composition of Formula 2 in the cathode active material. Based on this phenomenon, the inventors analyzed the improvement in high-temperature cycle performance and safety, believing the reasons may be as follows: When the chemical compositions of monocrystalline ternary materials and polycrystalline ternary materials satisfy Formulas 1 and 2, they can synergize and cooperate with each other, effectively reducing the occurrence of side reactions between the cathode material and the electrolyte, thereby reducing capacity loss and heat caused by side reactions; at the same time, by setting multiple cathode tabs on the cathode current collector, the heat generated by the medium-high nickel cathode active material during charging and discharging can be quickly conducted for rapid heat dissipation, effectively reducing the temperature rise of the battery under high-rate charging and discharging, thereby reducing the battery temperature and avoiding thermal runaway; therefore, the lithium-ion secondary battery of this invention can comprehensively improve the high-temperature cycle performance and safety performance of the battery while ensuring high energy density.

[0066] In addition, multiple positive electrode tabs help to disperse the current density and reduce the polarization of the system during charging and discharging, thereby effectively improving the low-temperature discharge performance of the battery.

[0067] Furthermore, the monocrystalline ternary material and / or polycrystalline ternary material also include a coating layer, wherein the coating layer of the monocrystalline ternary material and the polycrystalline ternary material independently includes at least one of a metal fluoride, a metal oxide, a metal borate compound, and a metal phosphate compound. This can further reduce side reactions between the positive electrode active material and the electrolyte, and further improve the cycle performance of the battery.

[0068] In one specific embodiment, the width W of the positive electrode tab is 3mm-10mm. For example, the width W is 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, 8mm, 8.5mm, 9mm, 9.5mm, or 10mm. When the width W of the positive electrode tab is within the aforementioned range, lithium plating problems caused by excessive current density at the positive electrode tab can be avoided, and it can also play a better role in heat dissipation, improving battery safety; at the same time, it can also ensure a high energy density and reduce the risk of contact between the positive and negative electrodes, further improving battery safety.

[0069] In one specific embodiment, N is 2-60. For example, the number N is 2, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, or 60. When the lithium-ion secondary battery satisfies Formula 1, further ensuring that the number N of the positive electrode tabs is within the aforementioned range not only allows for better heat dissipation, further improving the battery's high-temperature cycle performance and safety, but also better disperses the current density, improving the battery's low-temperature discharge performance; simultaneously, it also reduces energy density loss.

[0070] In one specific embodiment, the median particle size Dv50 of the single-crystal ternary material is smaller than that of the polycrystalline ternary material. This further reduces side reactions between the positive electrode active material and the electrolyte, thereby further reducing capacity loss and heat generated by side reactions.

[0071] In this invention, the median particle size Dv50 refers to the particle size value corresponding to a cumulative particle size distribution percentage of 50%, which can be obtained by testing with a laser particle size analyzer.

[0072] Preferably, the median particle size Dv50 of the single-crystal ternary material is 1μm-8μm. For example, the median particle size Dv50 is 1μm, 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 4.5μm, 5μm, 5.5μm, 6μm, 6.5μm, 7μm, 7.5μm, or 8μm. Within this range, the single-crystal ternary material particles are relatively small, which is beneficial for further improving the lithium-ion transport rate and enhancing the low-temperature discharge performance of the battery. At the same time, it can avoid the risk of puncturing the separator due to excessively large single-crystal ternary material particles, further improving the safety performance of the battery.

[0073] Preferably, the median particle size Dv50 of the polycrystalline ternary material is 8μm-18μm. For example, the median particle size Dv50 is 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, or 18μm. Within this range, the side reactions between the electrolyte and the positive electrode active material during charging and discharging can be further reduced, thereby giving the battery higher high-temperature cycle performance and safety; and within this range, it is beneficial to improve the transport of lithium ions within the particles, thereby improving the low-temperature discharge performance of the battery.

[0074] In one specific embodiment, the primary particles in the polycrystalline ternary material have a particle size of 200 nm to 800 nm. For example, the median particle size Dv50 of the primary particles is 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, or 800 nm. Within this range, it helps to shorten the diffusion path of lithium ions and further improve the discharge performance of the battery at low temperatures.

[0075] The primary particle size in this invention can be obtained by laser particle size analyzer or electron microscope (SEM).

[0076] In one specific embodiment, the median particle size Dv50 of the positive electrode active material is 2 μm-15 μm. For example, the median particle size Dv50 of the positive electrode active material is 2 μm, 4 μm, 6 μm, 8 μm, 10 μm, 12 μm, 14 μm, or 15 μm. Within this range, it helps to further shorten the diffusion path of lithium ions during charging and discharging, ensure the diffusion rate at low temperatures, and improve the low-temperature discharge performance of the battery.

[0077] In one specific embodiment, the positive electrode active material comprises, by mass percentage: 10wt%-90wt% monocrystalline ternary material and 10wt%-90wt% polycrystalline ternary material. Within this range, the monocrystalline and polycrystalline ternary materials can work synergistically to further reduce side reactions and heat generation, thereby giving the battery higher safety and high-temperature cycle performance. Simultaneously, it can further shorten the lithium-ion diffusion path, resulting in higher rate performance and low-temperature discharge performance. Moreover, within this range, the specific discharge capacity of the battery can be effectively improved.

[0078] In one specific embodiment, the positive current collector includes a positive current collector substrate and an epitaxial portion connected to each other. The epitaxial portion is located on one side of the positive current collector substrate and forms a positive electrode tab. At least a portion of the functional surface of the positive current collector substrate is provided with a positive functional layer.

[0079] Specifically, Figure 1 This is a schematic diagram of the structure of the positive electrode in one embodiment. Figure 2 This is a schematic diagram of the positive electrode sheet in another embodiment, such as... Figure 1 and Figure 2 As shown, the positive current collector includes a positive current collector substrate 1 and an epitaxial portion 2 connected to each other. The epitaxial portion 2 is located on one side of the positive current collector substrate 1 and forms a positive electrode tab 3. At least a portion of the surface of the positive current collector substrate 1 is provided with a positive functional layer.

[0080] The present invention does not specifically limit the formation method of the positive electrode tab 3, for example, it can be formed by die cutting.

[0081] In one specific embodiment, the lithium-nickel mixing ratio of the monocrystalline ternary material is 0.15%-5%, and / or the lithium-nickel mixing ratio of the polycrystalline ternary material is 0.5%-8%. For example, the lithium-nickel mixing ratio of the monocrystalline ternary material is 0.15%, 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, or 5.0%; and the lithium-nickel mixing ratio of the polycrystalline ternary material is 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, 6.5%, 7.0%, 7.5%, or 8.0%. Within this range, not only can lithium-ion secondary batteries achieve higher rate performance and high-temperature cycling performance, but the transformation from layered structure to spinel structure or even rock salt phase structure can also be effectively mitigated, capacity decay can be improved, and the first coulombic efficiency of the battery can be increased. At the same time, the occurrence of side reactions between the positive electrode active material and the electrolyte can be further reduced. Combined with the multi-tab structure of the positive electrode sheet, efficient heat conduction and heat dissipation can be achieved, thereby further improving the high-temperature cycling performance and safety of the battery.

[0082] The lithium-nickel mixing ratio in this invention is obtained by X-ray diffraction (XRD). Specifically, XRD testing is performed on the positive electrode active material to obtain an XRD spectrum, in which the ratio of the peak intensity of the diffraction peak of the 003 crystal plane to the peak intensity of the diffraction peak of the 104 crystal plane is the lithium-nickel mixing ratio of the positive electrode active material.

[0083] In one specific embodiment, the positive electrode functional layer includes an adjacent positive electrode active layer and an inorganic coating, wherein the inorganic coating is located between the positive electrode active layer and the positive electrode tab.

[0084] Preferably, the width of the inorganic coating is 0.5mm-5mm, and / or the thickness of the inorganic coating is 2μm-25μm;

[0085] Preferably, the inorganic coating includes at least one of boehmite, BaSO4, CaSiO3, CaSiO4, Al2O3, and TiO2.

[0086] For example, the width of the inorganic coating is 0.5mm, 1.0mm, 1.5mm, 2.0mm, 2.5mm, 3.0mm, 3.5mm, 4.0mm, 4.5mm or 5.0mm; the thickness of the inorganic coating is 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, 20mm, 21mm, 22mm, 23mm, 24mm or 25mm.

[0087] It should be noted that the thickness of the inorganic coating in this invention refers to the thickness of a single-sided coating.

[0088] Specifically, such as Figure 1 and Figure 2 As shown, the positive electrode functional layer includes an adjacent positive electrode active layer 12 and an inorganic coating 11, with the inorganic coating 11 located between the positive electrode active layer 12 and the positive electrode tab 3. Specifically, the positive electrode active layer 12 and the inorganic coating 11 have no overlapping portion in the thickness direction of the positive electrode sheet; that is, the positive electrode active layer 12 is disposed on a portion of the surface of the positive electrode current collector, and the inorganic coating 11 is disposed on a portion of the surface of the positive electrode current collector.

[0089] Preferably, there is an intersection region between the inorganic coating and the positive electrode active layer, and the inorganic coating in the intersection region is located on the surface of the positive electrode active layer away from the positive electrode current collector.

[0090] Specifically, in one embodiment, the positive electrode active layer 12 is disposed on a portion of the surface of the positive electrode current collector, and the inorganic coating 11 is disposed on a portion of the surface of the positive electrode current collector and a portion of the surface of the positive electrode active layer; in another embodiment, the positive electrode active layer 12 is disposed on a portion of the surface of the positive electrode current collector, and the inorganic coating 11 is disposed on a portion of the surface of the positive electrode active layer.

[0091] Because the single-crystal ternary material particles in the positive electrode active material have high hardness, excessive pressure during rolling may cause the particles to be squeezed into the foil. After the electrode is wound into a battery cell, these particles embedded in the foil are easily caused to break under the winding tension, leading to risks such as cell deformation and safety failure. This risk can be effectively eliminated by setting an inorganic coating between the positive electrode active layer and the positive electrode tabs. Furthermore, because this invention uses a multi-tab structure, many burrs are generated during the tab cutting process. In actual use, these burrs may puncture the separator, causing safety failure. Introducing an inorganic coating into the positive electrode functional layer can effectively avoid thermal runaway caused by burrs generated during tab cutting, improving battery safety.

[0092] Furthermore, when the width of the inorganic coating is within the aforementioned range, it can not only further reduce the degree of single crystal particles embedded in the foil, thereby reducing the risk of foil breakage; it can also further ensure that the burrs generated by the tab cutting will not pierce the diaphragm and cause safety risks; and it can also reduce the loss of energy density.

[0093] Furthermore, when the thickness of the inorganic coating is within the aforementioned range, it can effectively improve the degree of embedding of single crystal particles into the foil, thereby further reducing the risk of foil breakage. It can also effectively reduce the risk of the separator being punctured by large particles in the positive electrode active layer, improve safety, and reduce energy density loss.

[0094] In one specific embodiment, the lithium-ion secondary battery satisfies Equation 4.

[0095] 0.2≤(H×D2) / D1≤10 Equation 4

[0096] In Equation 4, H is the thickness of the inorganic coating, D1 is the particle size of the single-crystal ternary material Dv99, and H≥D1, D2 is the median particle size of the inorganic material Dv50.

[0097] In this invention, Dv99 refers to the particle size value corresponding to a cumulative particle size distribution percentage of 99%, which can be obtained by testing with a laser particle size analyzer.

[0098] When a lithium-ion secondary battery satisfies Equation 4, the inorganic coating, single-crystal ternary material, and electrode material particles can work together to prevent large ternary material particles in the positive electrode active material from protruding and piercing the separator, thus avoiding safety risks. In addition, the inorganic coating can also play a good role in isolation, preventing mutual interference during the tab die-cutting process, and further reducing energy density loss. While ensuring high energy density, it can also effectively improve battery safety.

[0099] In one specific embodiment, the lithium-ion secondary battery satisfies Equation 5.

[0100] 5≤B / A≤300 Equation 5

[0101] In Equation 5, A is the projected area of ​​the inorganic coating on the positive current collector, and B is the area of ​​the positive electrode sheet.

[0102] In this invention, the positive electrode area refers to the area excluding the tabs.

[0103] The introduction of inorganic coatings can exacerbate battery polarization to some extent, and an increase in the polarization layer area can lead to a decrease in the low-temperature discharge performance of the battery system. Simultaneously, the introduction of inorganic coatings also results in a loss of cell energy density. When a lithium-ion secondary battery satisfies Equation 5, the single-crystal ternary material and the inorganic coating can work synergistically to effectively reduce the degree of polarization caused by the inorganic coating, improve the low-temperature discharge performance of the battery system, and compensate for the loss of cell energy density.

[0104] In one specific embodiment, the particle size Dv99 of the single-crystal ternary material is 6μm-12μm. For example, the particle size Dv99 is 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, or 12μm. When the lithium-ion secondary battery satisfies Equation 4, and the particle size Dv99 of the single-crystal ternary material is within the aforementioned range, the diffusion path of lithium ions during charging and discharging can be effectively shortened. This not only ensures the high safety of the battery but also enables the battery to have high low-temperature discharge performance.

[0105] In one specific embodiment, the median particle size Dv50 of the inorganic material is 0.2 μm-4 μm. For example, the median particle size Dv50 is 0.2 μm, 0.5 μm, 1.0 μm, 1.5 μm, 2.0 μm, 2.5 μm, 3.0 μm, 3.5 μm, or 4.0 μm. When the lithium-ion secondary battery satisfies Formula 2, and the median particle size Dv50 of the inorganic material is within the aforementioned range, the risk of the positive electrode active material puncturing the separator can be further reduced.

[0106] In one specific embodiment, the lithium-ion secondary battery further includes a separator, the separator comprising a substrate and a coating layer, the coating layer comprising a polymer layer and / or a ceramic layer;

[0107] Preferably, the thickness of the substrate is 3μm-10μm, and / or the thickness of the coating layer is 1μm-7μm;

[0108] Preferably, the thickness of the polymer layer is 0.5 μm-4 μm, and / or the thickness of the ceramic layer is 0.5 μm-3 μm;

[0109] Preferably, the areal density of the diaphragm is 3 g / m³. 2 -20g / m 2 .

[0110] For example, the thickness of the substrate is 3μm, 3.5μm, 4μm, 4.5μm, 5μm, 5.5μm, 6μm, 6.5μm, 7μm, 7.5μm, 8μm, 8.5μm, 9μm, 9.5μm or 10μm.

[0111] For example, the thickness of the coating layer is 1μm, 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 4.5μm, 5μm, 5.5μm, 6μm, 6.5μm or 7μm.

[0112] For example, the thickness of the polymer layer is 0.5μm, 1.0μm, 1.5μm, 2.0μm, 2.5μm, 3.0μm, 3.5μm or 4μm.

[0113] For example, the thickness of the ceramic layer is 0.5μm, 1.0μm, 1.5μm, 2.0μm, 2.5μm or 3.0μm.

[0114] For example, the areal density of the diaphragm is 3 g / m³. 2 5g / m 2 7g / m 2 9g / m 2 11g / m 2 13g / m 2 15g / m 2 17g / m 2 19g / m 2 Or 20g / m 2 .

[0115] In this invention, the thickness of the coating layer, the thickness of the polymer layer, and the thickness of the ceramic layer all refer to the thickness on one side.

[0116] By including a coating layer in the separator, the thermal stability and mechanical strength of the separator can be effectively improved, preventing short circuits in high-temperature environments. At the same time, the puncture resistance of the separator can be effectively improved, thereby reducing the risk of the separator being punctured due to the high hardness of single crystal particles. It can also effectively avoid puncturing the separator due to burrs generated during the cutting of multi-tabs, further reducing the risk of cell short circuits and improving battery safety.

[0117] Furthermore, when the thickness of the substrate, the coating layer, the polymer layer and ceramic layer in the coating layer, and the areal density of the separator are within the aforementioned range, the thermal stability and mechanical strength of the separator can be further improved, avoiding short circuit problems at high temperatures; at the same time, the separator has higher puncture resistance, further avoiding the risk of the separator being punctured, making the battery safer.

[0118] The substrate in this invention is preferably any one of polyolefin-based polymer film, glass fiber film, polytetrafluoroethylene film, cellulose film, polyimide film, polyamide film, spandex, and aramid film; wherein, the polyolefin-based polymer film is preferably any one of polyethylene, polypropylene, ethylene / butene copolymer, and ethylene / methacrylate copolymer.

[0119] In this invention, the polymer in the polymer layer is preferably at least one of polymethyl methacrylate, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinylidene fluoride-trifluorochloroethylene copolymer, and polyoxyethylene.

[0120] The inorganic material in the ceramic layer of this invention is preferably at least one of boehmite, Mg(OH)2, Al2O3, SiO2, TiO2, ZnO, MgO, CaO, ZrO2, MnO, and WO3.

[0121] In one specific embodiment, the lithium-ion secondary battery further includes an electrolyte comprising nitrile additives. By including nitrile additives in the electrolyte, the nitrile additives synergistically interact with the positive electrode active material, forming a stable CEI protective film on the positive electrode surface during charge and discharge. This effectively suppresses the dissolution of transition metal ions, avoids side reactions between the electrolyte and the positive electrode active material, thereby further reducing heat generation from side reactions, improving high-temperature cycle performance, and enhancing the cell's safety performance.

[0122] Preferably, the mass percentage of nitrile additives in the electrolyte is 1wt%-10wt%. When the mass percentage of nitrile additives in the electrolyte is within the aforementioned range, they can better synergize with the positive electrode active material, helping to form a thicker and more stable CEI film on the positive electrode surface, while not causing an increase in the internal impedance of the battery, nor damaging the SEI film of the negative electrode, effectively improving the cycle performance of the battery.

[0123] Preferably, the electrolyte satisfies formula 6.

[0124] 1≤E / F≤17 Equation 6

[0125] In Formula 6, E represents the mass percentage of nitrile additives in the electrolyte, in wt%; F represents the molar content of nickel in the positive electrode active material relative to the transition metal elements.

[0126] Within this range, the synergistic effect between nitrile additives and ternary cathode active materials can be further enhanced, promoting the formation of the CEI film on the cathode surface, improving the uniformity and density of the CEI film, better preventing the dissolution of transition metal ions (especially Mn ions) during charging and discharging, and improving the structural stability of the cathode active material, thereby effectively alleviating capacity decay. At the same time, it is beneficial to further reduce the occurrence of side reactions between the cathode material and the electrolyte, thereby reducing the gas generation problem caused by solvent decomposition, and reducing heat generation during battery operation, thus improving battery safety.

[0127] Preferably, the mass percentage E of the nitrile additive in the electrolyte is 1wt%-10wt%. Exemplarily, the mass percentage is 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, or 10wt%. When the electrolyte satisfies Formula 6, and the nitrile additive is further within the above range, the nitrile additive can better synergize with the positive electrode active material, further suppressing the dissolution of transition metal ions (especially Mn ions) and reducing capacity decay; moreover, it can further reduce the occurrence of side reactions, giving the battery higher cycle performance and safety performance.

[0128] Preferably, the nitrile additives include succinate, glutaronitrile, adiponitrile, 1,5-dicyanopentane, 1,6-dicyanohexane, 1,7-dicyanoheptane, 1,8-dicyanoctane, 1,9-dicyanonane, 1,10-dicyanodecane, 1,12-dicyanodecadecane, tetramethylsuccinate, 2-methylglutaronitrile, 2,4-dimethylglutaronitrile, 2,2,4,4-tetramethylglutaronitrile, 1,4-dicyanopentane, 2,6-dicyanoheptane, 2,7-dicyanoctane, 2,8-dicyanonane, and 1,6-dicyanodecane. Alkane, 1,2-dicyanobenzene, 1,3-dicyanobenzene, 1,4-dicyanobenzene, 3,5-dioxa-heptanenitrile, 1,4-di(cyanoethoxy)butane, ethylene glycol di(2-cyanoethyl) ether, diethylene glycol di(2-cyanoethyl) ether, triethylene glycol di(2-cyanoethyl) ether, tetraethylene glycol di(2-cyanoethyl) ether, 3,6,9,12,15,18-hexaoxaeicosanoic acid dinitrile, 1,3-di(2-cyanoethoxy)propane, 1,4-di(2-cyanoethoxy)butane, 1,5-di(2-cyanoethyl)propane, 1,2-dicyanoethoxy)butane, 1,4-di(2-cyanoethoxy)butane, 1,5-di(2-cyanoethoxy)propane, 1,4-di(2-cyanoethoxy)butane, 1,5-di(2-cyanoethoxy)propane, 1,4-di(2-cyanoethoxy)propane, 1,4-di(2-cyanoethoxy)butane, 1,4-di(2-cyanoethoxy)prop ... oxy)pentane, ethylene glycol di(4-cyanobutyl) ether, 1,4-dicyano-2-butene, 1,4-dicyano-2-methyl-2-butene, 1,4-dicyano-2-ethyl-2-butene, 1,4-dicyano-2,3-dimethyl-2-butene, 1,4-dicyano-2,3-diethyl-2-butene, 1,6-dicyano-3-hexene, 1,6-dicyano-2-methyl-3-hexene, 1,6-dicyano-2-methyl-5-methyl-3-hexene, 1,3,5-pentanetricarbonyl, 1,2,3-propanetrimethyl... At least one of the following: nitrile, 1,3,6-hexanetrionitrile, glyceryltrionitrile, 1,2,6-hexanetrionitrile, 1,2,3-tris(2-cyanoethoxy)propane, 1,2,4-tris(2-cyanoethoxy)butane, 1,1,1-tris(cyanoethoxymethylene)ethane, 1,1,1-tris(cyanoethoxymethylene)propane, 3-methyl-1,3,5-tris(cyanoethoxy)pentane, 1,2,7-tris(cyanoethoxy)heptane, 1,2,6-tris(cyanoethoxy)hexane, and 1,2,5-tris(cyanoethoxy)pentane.

[0129] When the nitrile additive includes two or more of the aforementioned specific compounds, the present invention does not impose specific limitations on the ratio between the specific compounds.

[0130] In one specific embodiment, the lithium-ion secondary battery includes a cell formed by stacking and winding a positive electrode sheet, a negative electrode sheet, and a separator in sequence.

[0131] And / or, a lithium-ion secondary battery includes cells stacked in sequence, wherein a cell includes a positive electrode, a negative electrode and a separator stacked in sequence.

[0132] The present invention will be further described below through specific embodiments and comparative examples. Unless otherwise specified, the reagents, materials and instruments used below are all conventional reagents, materials and instruments, all of which are commercially available, and the reagents and materials involved can also be synthesized by conventional synthetic methods.

[0133] Example 1

[0134] 1) Preparation of single-crystal ternary materials: LiOH·H2O, Ni(OH)2, Co(OH)2, Mn(OH)2, and NaOH are mixed to obtain a mixture, wherein the molar ratio of LiOH·H2O, TM(OH)2, and NaOH is 1.5:1:0.5, where TM refers to Ni, Co, and Mn, and the molar ratio of Ni, Co, and Mn is 0.88:0.06:0.06; then Al2O3, Y2O3, and ZrO2 are added to the mixture, wherein Al2O3 accounts for 0.4 wt% of the mixture by mass, and Y2O3 accounts for 0.4 wt% of the mixture by mass. The content of Ni, Co, and Mn is 0.3 wt%, and ZrO2 accounts for 0.8 wt% of the mixture. The n(Li / TM) ratio is 1:1.05. Here, TM refers to the total molar amount of Ni, Co, and Mn. The mixed raw materials are placed in an oxygen atmosphere and sintered at 450°C at a heating rate of 5°C / min for 12 hours. After natural cooling to room temperature, the mixture is crushed, and Li3BO3 is added. The mixture is then heated to 350°C and held for 3 hours. Finally, after crushing and sieving, the single-crystal ternary material of this embodiment is obtained, with Dv50 of 3 μm and Dv99 of 7.5 μm. The chemical composition is Li... 0.978 (Al 0.008 Y 0.006 Zr 0.008 (Ni) 0.88 Co 0.06 Mn 0.06 O2;

[0135] 2) Preparation of polycrystalline ternary materials: LiOH·H2O, Ni(OH)2, Co(OH)2, Mn(OH)2, and NaOH are mixed to obtain a mixture, wherein the molar ratio of LiOH·H2O, TM(OH)2, and NaOH is 1.5:1:0.5, where TM refers to Ni, Co, and Mn; and the molar ratio of Ni, Co, and Mn is 0.8:0.1:0.1; then Al2O3 is added to the mixture, and the percentage of Al2O3 in the mixture is... The percentage is 0.2 wt%, where n(Li / TM) is 1:1.045, and TM is Ni, Co, and Mn. The mixed raw materials are placed in an oxygen atmosphere and sintered at 550°C at a heating rate of 5°C / min for 15 hours. After natural cooling to room temperature, the mixture is crushed, and Li3BO3 is added. The mixture is then heated to 350°C and held for 3 hours. Finally, after crushing and sieving, the polycrystalline ternary material of this embodiment is obtained, with a chemical composition of Li. 0.996 (Al 0.004 (Ni) 0.8 Co 0.1 Mn 0.1 O2, Dv50 is 13.5μm, and the median particle size Dv50 of primary particles is 450nm;

[0136] 3) Preparation of positive electrode sheet: The single-crystal ternary material and polycrystalline ternary material prepared above are physically mixed at a mass ratio of 1:1 to obtain a positive electrode active material with a Dv50 of 8.3 μm; the positive electrode active material, binder polyvinylidene fluoride (PVDF), conductive agent carbon black, and conductive agent carbon nanotubes are added to N-methylpyrrolidone (NMP) at a weight ratio of 95:1.5:1.5:2 and stirred under vacuum until the mixture becomes a homogeneous and fluid positive electrode slurry;

[0137] An inorganic slurry was prepared by mixing Al2O3, an inorganic material with a Dv50 of 2.0 μm, with polyvinylidene fluoride as a binder and N-methylpyrrolidone as a solvent in a ratio of 98:2.

[0138] The prepared positive electrode slurry and inorganic slurry were placed in two separate outlet holes and coated together on the coating area of ​​aluminum foil. Simultaneously, an empty foil area was reserved at the edge along the width of the current collector for subsequent tab cutting. The foil was then baked sequentially at temperature gradients of 70℃, 80℃, 95℃, 120℃, and 120℃, followed by drying in a 120℃ oven for 8 hours. Finally, it was rolled and slit to obtain a compacted density of 3.75 g / cm³ in this embodiment. 3 The positive electrode has an inorganic coating with a thickness of 8 μm and a width of 3 mm.

[0139] The positive electrode sheet obtained above is die-cut into the reserved empty foil area using an electrode tab mold to obtain a positive electrode sheet with electrode tabs. The width of the positive electrode tabs is 6mm, and the width is consistent, with a number of 22.

[0140] 4) Negative electrode preparation: Graphite (negative electrode active material), sodium carboxymethyl cellulose (CMC-Na) (thickener), styrene-butadiene rubber (binder), and acetylene black (conductive agent) were mixed in a weight ratio of 97:1:1:1. Deionized water was added, and a negative electrode slurry was obtained under vacuum stirring. The negative electrode slurry was uniformly coated onto carbon-coated copper foil, with empty foil areas reserved at the edges along the width of the current collector for subsequent tab cutting. After air drying at room temperature, the foil was transferred to an 80℃ oven for drying for 10 hours. The resulting product was then rolled and slit to obtain a compacted density of 1.7 g / cm³. 3 The negative electrode plate;

[0141] The negative electrode obtained above is die-cut into the reserved empty foil area using an electrode tab mold to obtain a positive electrode with tabs. The positive electrode tabs are 6mm wide, have a uniform width, and number 22.

[0142] 5) A conventional commercially available diaphragm is selected, with polyethylene as the substrate, Al2O3 as the ceramic layer, and PVDF as the polymer layer. Specifically, a 1μm thick ceramic layer and a polymer layer are respectively deposited on both functional surfaces of a 5μm thick substrate. Then, a polymer layer is deposited on the outer surface of the ceramic layer. The two polymer layers are of equal thickness, with a total thickness of 1.5μm. The diaphragm surface density is 5.8 g / m³. 2 ;

[0143] 6) In a glove box filled with inert gas (argon) (H2O < 0.1 ppm, O2 < 0.1 ppm), ethylene carbonate, propylene carbonate, diethyl carbonate, and propyl propionate are mixed evenly in a mass percentage ratio of 15 wt%: 10 wt%: 10 wt%: 65 wt%. Then, fully dried lithium hexafluorophosphate (LiPF6) (molar concentration of 1.25 mol / L) is quickly added to dissolve it in a non-aqueous organic solvent and stirred evenly. Finally, succinic acid additive is added, and the mass percentage of succinic acid in the electrolyte is controlled to be 5 wt%. After passing the tests for moisture and free acid, the electrolyte of this embodiment is obtained.

[0144] 7) Preparation of lithium-ion secondary battery: The prepared positive electrode, negative electrode and separator are stacked in sequence, the separator is placed between the positive electrode and the negative electrode, and the cells are wound up to obtain the battery cell. The positive electrode tabs are overlapped separately and the negative electrode tabs are overlapped separately to obtain a bare core with a multi-tab winding structure. The bare battery cell is placed in the outer packaging foil, and the electrolyte is injected into the battery cell in the glove box. After vacuum sealing, standing, formation, shaping and sorting, a soft-pack lithium-ion secondary battery with a capacity of 3.5Ah is finally obtained.

[0145] Example 2

[0146] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1, except that in step 2), the nickel content in the polycrystalline ternary material is adjusted to 0.6%, specifically, the chemical composition is Li 0.996 (Al 0.004 (Ni) 0.6 Co 0.2 Mn 0.2 )O2.

[0147] Example 3

[0148] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1, except that in step 2), the nickel content in the polycrystalline ternary material is adjusted to 0.7, specifically, the chemical composition is Li 0.996 (Al 0.004 (Ni) 0.7 Co 0.1 Mn 0.2 )O2.

[0149] Example 4

[0150] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1, except that in step 2), the nickel content in the polycrystalline ternary material is adjusted to 0.98%, specifically, the chemical composition is Li 0.996 (Al 0.004 (Ni) 0.98 Co 0.01 Mn 0.01 )O2.

[0151] Example 5

[0152] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1, except that in step 1), the nickel content in the single-crystal ternary material is adjusted to 0.6%, specifically, the chemical composition is Li 0.978 (Al 0.008 Y 0.006 Zr 0.008 (Ni)0.6 Co 0.2 Mn 0.2 )O2.

[0153] Example 6

[0154] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1, except that in step 1), the nickel content in the single-crystal ternary material is adjusted to 0.7, specifically, the chemical composition is Li 0.978 (Al 0.008 Y 0.006 Zr 0.008 (Ni) 0.7 Co 0.1 Mn 0.2 )O2.

[0155] Example 7

[0156] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1, except that in step 1), the nickel content in the single-crystal ternary material is adjusted to 0.9, specifically, the chemical composition is Li 0.978 (Al 0.008 Y 0.006 Zr 0.008 (Ni) 0.9 Co 0.05 Mn 0.05 )O2.

[0157] Example 8

[0158] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1, except that in step 1), the nickel content in the single-crystal ternary material is adjusted to 0.98%, specifically, the chemical composition is Li 0.978 (Al 0.008 Y 0.006 Zr 0.008 (Ni) 0.98 Co 0.01 Mn 0.01 )O2.

[0159] Example 9

[0160] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1. The difference is that in step 3), the mass percentage of single-crystal ternary material in the positive electrode active material is adjusted to 60wt%, and the mass percentage of polycrystalline ternary material is adjusted to 40wt%.

[0161] Example 10

[0162] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1. The difference is that in step 3), the mass percentage of single-crystal ternary material in the positive electrode active material is adjusted to 70wt%, and the mass percentage of polycrystalline ternary material is adjusted to 30wt%.

[0163] Example 11

[0164] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1. The difference is that in step 3), the mass percentage of single-crystal ternary material in the positive electrode active material is adjusted to 90wt%, and the mass percentage of polycrystalline ternary material is adjusted to 10wt%.

[0165] Example 12

[0166] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1. The difference is that in step 3), the mass percentage of single-crystal ternary material in the positive electrode active material is adjusted to 10wt%, and the mass percentage of polycrystalline ternary material is adjusted to 90wt%.

[0167] Example 13

[0168] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1. The difference is that in step 1), the Dv50 of the single crystal ternary material is adjusted to 1 μm and the Dv99 is adjusted to 6 μm.

[0169] Example 14

[0170] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1. The difference is that in step 1), the Dv50 of the single crystal ternary material is adjusted to 5μm and the Dv99 is adjusted to 10μm.

[0171] In step 3), the thickness of the inorganic coating is adjusted to 12 μm.

[0172] Example 15

[0173] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1. The difference is that in step 1), the Dv50 of the single crystal ternary material is adjusted to 8μm and the Dv99 is adjusted to 12μm.

[0174] In step 3), the thickness of the inorganic coating is adjusted to 13 μm.

[0175] Example 16

[0176] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1. The difference is that in step 2), the Dv50 of the polycrystalline ternary material is adjusted to 8μm.

[0177] Example 17

[0178] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1. The difference is that in step 2), the Dv50 of the polycrystalline ternary material is adjusted to 10μm.

[0179] Example 18

[0180] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1. The difference is that in step 2), the Dv50 of the polycrystalline ternary material is adjusted to 15μm.

[0181] Example 19

[0182] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1. The difference is that in step 2), the Dv50 of the polycrystalline ternary material is adjusted to 18μm.

[0183] Example 20

[0184] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1. The difference is that in step 2), the Dv50 of the primary particles of the polycrystalline ternary material is adjusted to 200 μm.

[0185] Example 21

[0186] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1. The difference is that in step 2), the Dv50 of the primary particles of the polycrystalline ternary material is adjusted to 800 μm.

[0187] Example 22

[0188] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1. The difference is that in step 3), the width of the positive electrode tab is adjusted to 3mm.

[0189] Example 23

[0190] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1. The difference is that in step 3), the width of the positive electrode tab is adjusted to 8mm.

[0191] Example 24

[0192] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1. The difference is that in step 3), the number N of the positive electrode tabs is adjusted to 2.

[0193] Example 25

[0194] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1, except that in step 3), the number N of the positive electrode tabs is adjusted to 15.

[0195] Example 26

[0196] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1. The difference is that in step 3), the number N of the positive electrode tabs is adjusted to 30.

[0197] Example 27

[0198] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1. The difference is that in step 3), the width of the inorganic coating is adjusted to 0.5 mm.

[0199] Example 28

[0200] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1. The difference is that in step 3), the width of the inorganic coating is adjusted to 2 mm.

[0201] Example 29

[0202] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1. The difference is that in step 3), the width of the inorganic coating is adjusted to 5 mm.

[0203] Example 30

[0204] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1. The difference is that in step 3), the thickness of the inorganic coating is adjusted to 6 mm.

[0205] Example 31

[0206] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1, except that in step 3), the thickness of the inorganic coating is adjusted to 25 mm.

[0207] Example 32

[0208] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1. The difference is that in step 3), the Dv50 of the inorganic material is adjusted to 0.2 μm.

[0209] Example 33

[0210] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1. The difference is that in step 3), the Dv50 of the inorganic material is adjusted to 4μm.

[0211] Example 34

[0212] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1, except that in step 6), the mass percentage of succinic anion in the electrolyte is adjusted to 1 wt%.

[0213] Example 35

[0214] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1, except that in step 6), the mass percentage of succinic anion in the electrolyte is adjusted to 10 wt%.

[0215] Example 36

[0216] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1, except that in step 6), succinic anion is replaced with 1,5-dicyanopentane.

[0217] Example 37

[0218] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1, except that in step 6), succinic anion is replaced with tetramethylsuccinic anion.

[0219] Example 38

[0220] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1, except that in step 6), succinic anion is replaced with 1,4-dicyanopentane.

[0221] Example 39

[0222] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1, except that in step 6), succinic anion is replaced with 1,2-dicyanophenyl.

[0223] Example 40

[0224] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1. The difference is that in step 1), the Dv50 of the single crystal ternary material is adjusted to 8.5 μm and the Dv99 is adjusted to 15 μm.

[0225] In step 3), the thickness of the inorganic coating is adjusted to 20 μm.

[0226] Example 41

[0227] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1. The difference is that in step 2), the Dv50 of the polycrystalline ternary material is adjusted to 20 μm, and the Dv50 of the primary particles is adjusted to 950 nm.

[0228] Example 42

[0229] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1. The difference is that in step 1), the lithium-nickel mixing ratio of the single-crystal ternary material is adjusted to 6%.

[0230] Example 43

[0231] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1. The difference is that in step 2), the lithium-nickel mixing ratio of the polycrystalline ternary material is adjusted to 9%.

[0232] Example 44

[0233] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1. The difference is that in step 3), no inorganic coating is set on the positive electrode functional layer.

[0234] Example 45

[0235] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1. The difference is that in step 3), the width of the inorganic coating is adjusted to 0.2 mm.

[0236] Example 46

[0237] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1. The difference is that in step 3), the thickness of the inorganic coating is adjusted to 4 μm.

[0238] Example 47

[0239] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1, except that in step 1), the D99 of the single crystal ternary material is adjusted to 6μm.

[0240] In step 3), the Dv50 of the inorganic material is adjusted to 3μm, and the thickness of the inorganic coating is adjusted to 20μm.

[0241] Example 48

[0242] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1, except that in step 1), the D99 of the single crystal ternary material is adjusted to 6μm.

[0243] In step 3), the width of the inorganic coating is adjusted to 10mm.

[0244] Example 49

[0245] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1, except that in step 1), the Dv99 of the single crystal ternary material is adjusted to 13.5 μm.

[0246] In step 3), the thickness of the inorganic coating is adjusted to 15 μm.

[0247] Example 50

[0248] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1, except that in step 6), the mass percentage of succinic anion in the electrolyte is adjusted to 12 wt%.

[0249] Example 51

[0250] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1. The difference is that in step 3), the mass percentage of single-crystal ternary material in the positive electrode active material is adjusted to 8 wt%, and the mass percentage of polycrystalline ternary material is adjusted to 92 wt%.

[0251] Example 52

[0252] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1. The difference is that in step 3), the mass percentage of single-crystal ternary material in the positive electrode active material is adjusted to 92wt%, and the mass percentage of polycrystalline ternary material is adjusted to 8wt%.

[0253] Example 53

[0254] The method for manufacturing the lithium-ion secondary battery in this embodiment is basically the same as that in Embodiment 1. The difference is that in step 2), the Dv50 of the primary particles of the polycrystalline ternary material is adjusted to 1 μm.

[0255] Example 54

[0256] The method for manufacturing the lithium-ion secondary battery in this embodiment is basically the same as that in Embodiment 1. The difference is that in step 2), the Dv50 of the monocrystalline ternary material is adjusted to 12μm, the Dv99 is adjusted to 18μm, and the Dv50 of the polycrystalline ternary material is adjusted to 10μm.

[0257] Example 55

[0258] The method for manufacturing the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1. The difference is that the Dv50 of the positive electrode active material after mixing is adjusted to 17.2 μm. At this time, the particle size Dv50 of the single crystal ternary material is 10 μm, Dv99 is 16.3 μm, and the Dv50 of the polycrystalline ternary material is 25 μm.

[0259] Example 56

[0260] The method for fabricating the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1, except that the chemical formula of the single-crystal ternary battery is Li. 0.978 (Al 0.008 Y 0.006 Zr 0.008 (Ni) 0.9 Co 0.05 Mn 0.05 O2, the chemical formula of the polycrystalline ternary is Li 0.996 (Al 0.004 (Ni) 0.9 Co 0.05 Mn 0.05 O2, the content of nitrile additives in the electrolyte is 0.5%.

[0261] Example 57

[0262] The method for manufacturing the lithium-ion secondary battery in this embodiment is basically the same as that in Embodiment 1. The difference is that the thickness of the inorganic coating is adjusted to 25 μm and the median particle size Dv50 of the inorganic material is adjusted to 4 μm.

[0263] Comparative Example 1

[0264] The method for manufacturing the lithium-ion secondary battery in this comparative example is basically the same as that in Example 1. The difference is that in step 3), the positive electrode active material is replaced with the single-crystal ternary material prepared in step 1), excluding the polycrystalline ternary material.

[0265] Comparative Example 2

[0266] The method for manufacturing the lithium-ion secondary battery in this comparative example is basically the same as that in Example 1. The difference is that in step 3), the positive electrode active material is replaced with the polycrystalline ternary material prepared in step 2), excluding the single-crystal ternary material.

[0267] Comparative Example 3

[0268] The method of manufacturing the lithium-ion secondary battery in this comparative example is basically the same as that in Example 1, except that in step 3), only one tab is set at the edge of the positive electrode.

[0269] In step 4), only one tab is set at the edge of the negative electrode plate.

[0270] Comparative Example 4

[0271] The preparation method of the lithium-ion secondary battery in this embodiment is basically the same as that in Example 1. The difference is that in step 3), the width of the positive electrode tab is adjusted to 2mm.

[0272] See Table 1 for specific parameters.

[0273] Table 1

[0274]

[0275]

[0276]

[0277] Table 2

[0278]

[0279]

[0280]

[0281] Test case

[0282] 1. The discharge specific capacity of the lithium-ion secondary batteries prepared in the above embodiments and comparative examples was tested, including the following steps:

[0283] Under the conditions of a test temperature of 25℃ and a test voltage range of 3.0V-4.3V, charging and discharging were performed, with a charge / discharge rate of 0.5C / 0.5C and a cutoff current of 0.025C.

[0284] The test results are shown in Table 3.

[0285] 2. The safety performance of the lithium-ion secondary batteries prepared in the above embodiments and comparative examples was tested, including the following steps:

[0286] Using 20 lithium-ion rechargeable batteries as a group, the batteries were charged at a constant current rate of 0.5C to 4.3V at 25℃, then charged at a constant voltage rate to a cutoff current of 0.025C. After standing for 2 hours, the fully charged batteries were placed in a hot chamber and heated from room temperature to 132℃ at a rate of 5℃ / min, and maintained for 60 minutes. If the batteries did not explode or catch fire, they were considered PASS; otherwise, they were considered FAIL. The test results are shown in Table 3.

[0287] 3. The low-temperature discharge performance of the lithium-ion secondary batteries prepared in the above embodiments and comparative examples was tested, including the following steps:

[0288] The battery was first discharged at 0.2C to 3.0V at an ambient temperature of (25±3)℃, and then left to rest for 5 minutes. It was then charged at 0.7C. When the cell terminal voltage reached the charging limit voltage (4.3V), constant voltage charging was switched until the charging current ≤ 0.02C, at which point charging was stopped. After resting for 5 minutes, the battery was discharged at 0.2C to 3.0V, and the discharge capacity was recorded as the room temperature capacity Q1. The battery was then charged at 0.7C. When the cell terminal voltage reached the charging limit voltage, constant voltage charging was switched until the charging current ≤ the cutoff current, at which point charging was stopped. The fully charged battery was then left to rest at -20±2℃ for 4 hours, and then discharged at 0.2C to the cutoff voltage of 3.0V, and the discharge capacity Q2 was recorded. The low-temperature discharge capacity retention rate (%) is calculated as Q2 / Q1 × 100%. The test results are shown in Table 3.

[0289] 4. The high-temperature cycle performance of the lithium-ion secondary batteries prepared in the above embodiments and comparative examples was tested, including the following steps:

[0290] The battery was placed in a constant temperature environment of 45℃ and charged and discharged at a rate of 1.8C / 4.0C. The cutoff voltage range was 2.5V-4.3V. The battery was charged and discharged 500 times. The initial discharge capacity was recorded as C0 and the discharge capacity after 500 cycles was recorded as C1. The high temperature cycle capacity retention rate (%) = C1 / C0 × 100%. The test and calculation results are shown in Table 3.

[0291] 5. The energy density of the lithium-ion secondary batteries prepared in the above embodiments and comparative examples was tested, including the following steps:

[0292] Under the conditions of a test temperature of 25℃ and a test voltage range of 3.0V-4.3V, charging and discharging were performed. The charge / discharge rate was 0.5C / 0.5C, and the cutoff current was 0.025C. The energy of the discharged cell (in Wh) was recorded, and the cell weight (in g) was also recorded. The energy density (Wh / kg) = discharge energy / (cell weight / 1000). The test results are shown in Table 3.

[0293] Table 3

[0294]

[0295]

[0296]

[0297] From Tables 1-3, we can see that:

[0298] The lithium-ion secondary batteries in Examples 1-57 exhibit higher overall performance compared to those in Comparative Examples 1-4. Specifically, Example 5 achieved a furnace temperature test pass rate of 19 / 20, with a corresponding low-temperature discharge capacity retention of 81.0% and a 500-cycle high-temperature capacity retention of 92.4%. In contrast, while Comparative Example 1 showed higher high-temperature cycling performance, its furnace temperature test pass rate was only 3 / 20. Comparative Example 2 demonstrated good low-temperature discharge performance, but its furnace temperature test pass rate was also only 3 / 20, resulting in a high-temperature cycling capacity retention of only 80.2%. Comparative Examples 3 and 4 showed lower furnace temperature safety performance, low-temperature discharge performance, and high-temperature cycling performance. Therefore, the lithium-ion secondary battery of this invention possesses superior low-temperature discharge performance, high-temperature cycling performance, and safety performance.

[0299] 5. Perform ICP testing on the positive electrode sheets in the above embodiments and comparative examples, including the following steps:

[0300] 1) Under the conditions of a test temperature of 25℃ and a test voltage range of 3.0V-4.3V, charge and discharge were performed. The charge and discharge rate was 0.5C / 0.5C and the cutoff current was 0.025C. At this time, the battery was 100% SOC. Under this condition, the positive electrode was disassembled to obtain the positive electrode sheet. The positive electrode sheet was immersed in a dimethyl carbonate (DMC) solution for 30 minutes. After immersion, it was taken out and dried in a 120℃ oven for 6 hours.

[0301] 2) Place the dried electrode in a tube furnace and sinter it at high temperature. Set the tube furnace sintering temperature to 300℃ and the sintering time to 4h. After sintering, allow it to cool naturally and place the cooled electrode in a sealed glass bottle.

[0302] 3) Place the glass bottle containing the electrode in an ultrasonic machine and sonicate for 15 minutes. After sonicating, remove the bottle and gently rub the powder to obtain positive electrode powder in a 100% SOC state.

[0303] 4) The above-mentioned positive electrode powder was tested using atomic absorption spectrometry (ICP) to obtain the content values ​​of each element in the positive electrode powder.

[0304] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A lithium-ion secondary battery, characterized by comprising: The lithium ion secondary battery comprises a positive electrode sheet; the positive electrode sheet comprises a positive electrode current collector provided with N positive electrode tabs, N>=2; a positive electrode functional layer comprising a positive electrode active material is arranged on at least part of the functional surface of the positive electrode current collector; the positive electrode active material comprises single-crystal ternary material and polycrystal ternary material; The single-crystal ternary material has a chemical composition of formula 1, Li p Me m (Ni x Co y Mn z )O2Formula 1 In formula 1, 0.9<=p<=1.1, 0.01<=m<=0.5, 0.6<=x<=0.98, 0<=y<=0.4, 0<=z<=0.4, and Me comprises at least one of Al, Mg, Zr, B, Y, Sr, W, Ti, Nb, Mo, La, Sb, and Sr; The polycrystal ternary material has a chemical composition of formula 2, Li q Me n (Ni a Co b Mn c )O2Formula 2 In formula 2, 0.9<=q<=1.1, 0.01<=n<=0.5, 0.6<=a<=0.98, 0<=b<=0.4, 0<=c<=0.4, and Me comprises at least one of Al, Mg, Zr, B, Y, Sr, W, Ti, Nb, Mo, La, Sb, and Sr; The lithium ion secondary battery satisfies formula 3, 0.2<= (C*N) / W <=7.5 formula 3 In formula 3, C is the molar content of nickel in the positive electrode active material relative to the transition metal elements; and W is the width of the positive electrode tab, in mm.

2. The lithium-ion secondary battery according to claim 1, characterized by The width W of the positive electrode tab is 3-10 mm, and / or the N is 2-60.

3. The lithium-ion secondary battery according to claim 1 or 2, characterized by The median particle size Dv50 of the single-crystal ternary material is smaller than the median particle size Dv50 of the polycrystal ternary material; Preferably, the median particle size Dv50 of the single-crystal ternary material is 1-8 mu m, and / or the median particle size Dv50 of the polycrystal ternary material is 8-18 mu m.

4. The lithium-ion secondary battery according to any one of claims 1 to 3, characterized by The particle size of the primary particles in the polycrystal ternary material is 200-800 nm, and / or the median particle size Dv50 of the positive electrode active material is 2-15 mu m.

5. The lithium-ion secondary battery according to any one of claims 1 to 4, characterized by The positive electrode active material comprises, in mass percentage, 10-90 wt% of the single-crystal ternary material and 10-90 wt% of the polycrystal ternary material.

6. The lithium-ion secondary battery according to any one of claims 1 to 5, characterized by The positive electrode current collector comprises a positive electrode current collector base and an extension part connected to each other, the extension part is located on one side of the positive electrode current collector base, the extension part forms the positive electrode tab, and at least part of the functional surface of the positive electrode current collector base is provided with the positive electrode functional layer.

7. The lithium-ion secondary battery according to any one of claims 1 to 6, characterized by The lithium-nickel mixing rate of the single-crystal ternary material is 0.15-5%, and / or the lithium-nickel mixing rate of the polycrystal ternary material is 0.5-8%.

8. The lithium-ion secondary battery according to any one of claims 1 to 7, characterized by The positive electrode functional layer comprises an adjacent positive electrode active layer and an inorganic coating layer, and the inorganic coating layer is located between the positive electrode active layer and the positive electrode tab; Preferably, the width of the inorganic coating layer is 0.5-5 mm, and / or the thickness of the inorganic coating layer is 2-25 mu m; Preferably, the inorganic coating layer comprises at least one of boehmite, BaSO4, CaSiO3, CaSiO4, Al2O3, and TiO2.

9. The lithium-ion secondary battery according to claim 8, characterized by The lithium ion secondary battery satisfies formula 4 and / or formula 5, 0.2<= (H*D2) / D1 <=10 formula 4 In formula 4, H is the thickness of the inorganic coating layer, D1 is the particle size Dv99 of the single-crystal ternary material, and H≥D1, D2 is the median particle size Dv50 of the inorganic material; 5≤B / A≤300 Formula 5 In formula 5, A is the normal projection area of the inorganic coating layer on the positive current collector, and B is the area of the positive electrode tab. Preferably, the particle size Dv99 of the single-crystal ternary material is 6 μm-12 μm, and / or the median particle size Dv50 of the inorganic material is 0.2 μm-4 μm.

10. The lithium-ion secondary battery according to any one of claims 1 to 9, characterized by The lithium ion secondary battery further comprises a separator, the separator comprising a substrate, a coating layer, the coating layer comprising a polymer layer and / or a ceramic layer; Preferably, the thickness of the substrate is 3 μm-10 μm, and / or the thickness of the coating layer is 1 μm-7 μm; Preferably, the thickness of the polymer layer is 0.5 μm-4 μm, and / or the thickness of the ceramic layer is 0.5 μm-3 μm; Preferably, the face density of the separator is 3 g / m 2 - 20 g / m 2 .

11. The lithium-ion secondary battery according to any one of claims 1 to 10, characterized by The lithium ion secondary battery further comprises an electrolyte, the electrolyte comprising a nitrile-based additive; Preferably, the electrolyte satisfies formula 6, 1≤E / F≤17 Formula 6 In formula 6, E is the mass percentage content of the nitrile-based additive in the electrolyte, in wt%; F is the molar content of nickel element in the transition metal elements in the positive electrode active material; Preferably, the mass percentage content E of the nitrile-based additive in the electrolyte is 1 wt%-10 wt%. Preferably, the nitrile additive includes at least one of butanedinitrile, pentanedinitrile, hexanedinitrile, 1,5-dicyanopentane, 1,6-dicyanohexane, 1,7-dicyanoheptane, 1,8-dicyanoctane, 1,9-dicyanononane, 1,10-dicyanodecane, 1,12-dicyanododecane, tetramethylbutanedinitrile, 2-methylpentanedinitrile, 2,4-dimethylpentanedinitrile, 2,2,4,4-tetramethylpentanedinitrile, 1,4-dicyanopentane, 2,6-dicyanoheptane, 2,7-dicyanoctane, 2,8-dicyanononane, 1,6-dicyanodecane, 1,2-dicyanobenzene, 1,3-dicyanobenzene, 1,4-dicyanobenzene, 3,5-dioxa-heptanedinitrile, 1,4-bis(cyanoethoxy)butane, ethylene glycol bis(2-cyanoethyl) ether, diethylene glycol bis(2-cyanoethyl) ether, triethylene glycol bis(2-cyanoethyl) ether, tetraethylene glycol bis(2-cyanoethyl) ether, 3,6,9,12,15,18-hexaoxaicosanedinitrile, 1,3-bis(2-cyanoethoxy)propane, 1,4-bis(2-cyanoethoxy)butane, 1,5-bis(2-cyanoethoxy)pentane, ethylene glycol bis(4-cyanobutyl) ether, 1,4-dicyano-2-butene, 1,4-dicyano-2-methyl-2-butene, 1,4-dicyano-2-ethyl-2-butene, 1,4-dicyano-2,3-dimethyl-2-butene, 1,4-dicyano-2,3-diethyl-2-butene, 1,6-dicyano-3-hexene, 1,6-dicyano-2-methyl-3-hexene, 1,6-dicyano-2-methyl-5-methyl-3-hexene, 1,3,5-pentanetricarbonitrile, 1,2,3-propanetricarbonitrile, 1,3,6-hexanetricarbonitrile, glycerol tricarbonitrile, 1,2,6-hexanetricarbonitrile, 1,2,3-tris(2-cyanoethoxy)propane, 1,2,4-tris(2-cyanoethoxy)butane, 1,1,1-tris(cyanoethoxymethylene)ethane, 1,1,1-tris(cyanoethoxymethylene)propane, 3-methyl-1,3,5-tris(cyanoethoxy)pentane, 1,2,7-tris(cyanoethoxy)heptane, 1,2,6-tris(cyanoethoxy)hexane, and 1,2,5-tris(cyanoethoxy)pentane.

12. The lithium-ion secondary battery according to any one of claims 1 to 11, characterized by The lithium ion secondary battery includes an electrode core in which a positive electrode sheet, a negative electrode sheet, and a separator are sequentially stacked and wound; Or, the lithium ion secondary battery includes an electrode core monomer sequentially stacked, and the electrode core monomer includes a positive electrode sheet, a negative electrode sheet, and a separator sequentially stacked.

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