Soft package cylindrical battery and power utilization device

Abstract

In order to solve the problems that an existing soft package battery is prone to deformation and low in safety when subjected to large external force, the invention provides a soft package cylindrical battery which comprises a roll core, the roll core comprises a positive plate, a diaphragm and a negative plate, and the negative plate comprises a negative current collector and a negative active material layer arranged on the surface of the negative current collector. The sum of the thicknesses of the negative electrode active material layers is 12-20 [mu] m; the negative electrode active material layer comprises a negative electrode silicon-based active material, and the negative electrode silicon-based active material comprises pure silicon particles; a positive tab is arranged at the first end of the roll core, a negative tab is arranged at the second end of the roll core, and the projection of the positive tab on the end surface of the second end of the roll core does not intersect with the negative tab along the axis direction of the roll core; as the positive tab and the negative tab are not on the same straight line, when the roll core is subjected to a large external force, the same deformation does not generate a large counter-acting force, and the positive and negative tabs and the positive and negative plates are not easy to contact, so that the roll core is not easy to fire or explode, and the safety of batch application of the roll core is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a soft-package cylindrical battery and an electrical device. Background Art Lithium-ion batteries have become an ideal power source for portable electronic devices such as e-cigarettes due to their high energy density, long cycle life, and small volume-to-weight ratio. In recent years, with the continuous development of the e-cigarette market, consumers' expectations for e-cigarettes have also been continuously upgraded. They not only pursue long-lasting battery life, but also have higher and higher demands for battery cell energy density, which is also the case in the field of soft-pack cylindrical batteries.

[0002] However, as the energy density of soft-pack cylindrical batteries increases, the safety and reliability of the batteries also become worse. If the original conventional battery cell structure design is still used, its safety and reliability cannot meet industry requirements. This is also an important bottleneck restricting the improvement of energy density in the soft-pack cylindrical field.

[0003] like Figure 1 As shown, in the prior art, the positive and negative tabs in the soft-pack battery are arranged at both ends of the core, and along the length direction of the core, the extension line of the positive tab coincides with the negative tab; when a large external force (such as ≥13KN) is applied to the surface of the core, the core will be greatly deformed. Since the positive and negative tabs are located on the same straight line, when the core is greatly deformed, the positive and negative tabs and the positive and negative electrode sheets are easily in contact, causing the core to catch fire or explode, which brings hidden dangers to the mass application of the core. Therefore, how to overcome the above-mentioned technical problems and defects has become a key issue that needs to be solved. Summary of the invention

[0004] In view of the problems that existing soft-pack batteries have low energy density, are easily deformed when subjected to large external forces, and have low safety, the present invention provides a soft-pack cylindrical battery and an electrical device.

[0005] The technical solution adopted by the present invention to solve the above technical problems is as follows: In one aspect, the present invention provides a soft-pack cylindrical battery, comprising a soft-pack shell and a winding core disposed in the soft-pack shell, wherein the winding core comprises a positive electrode sheet, a separator and a negative electrode sheet; The negative electrode sheet comprises a negative electrode current collector and negative electrode active material layers disposed on both sides of the surface of the negative electrode current collector, and the total thickness of the negative electrode active material layers is 12 μm-20 μm; The negative electrode active material layer includes a negative electrode silicon-based active material, the negative electrode silicon-based active material includes pure silicon particles, and the mass percentage of the pure silicon particles in the negative electrode silicon-based active material is 65-100%; The positive electrode sheet, the separator and the negative electrode sheet are stacked and wound to form the winding core, in which the positive electrode sheet and the negative electrode sheet are separated by the separator; the positive electrode sheet is provided with a positive electrode ear, and the positive electrode ear is located at the first end of the winding core; the negative electrode sheet is provided with a negative electrode ear, and the negative electrode ear is located at the second end of the winding core; the projection of the positive electrode ear on the end surface of the second end of the winding core along the axial direction of the winding core does not intersect with the projection of the negative electrode ear on the end surface of the second end of the winding core along the axial direction of the winding core.

[0006] Optionally, the thickness of the negative electrode sheet is 18 μm-28 μm.

[0007] Optionally, the double-sided surface density of the negative electrode sheet is 1.6-2.4 mg / cm 2 The compaction density of the negative electrode sheet is 1.1-1.3 g / cm 3 .

[0008] Optionally, the projection of the positive electrode ear on the second end surface of the core along the axial direction of the core and the projection of the negative electrode ear on the second end surface of the core along the axial direction of the core are respectively located on both sides of the central axis of the core, and the positive electrode ear is arranged in parallel with the negative electrode ear.

[0009] Optionally, a projection of the positive electrode tab on the second end surface of the winding core along the axial direction of the winding core and a projection of the negative electrode tab on the second end surface of the winding core along the axial direction of the winding core are symmetrically arranged about the central axis of the winding core.

[0010] Optionally, the projection of the positive electrode sheet on the diaphragm is located inside the projection of the negative electrode sheet on the diaphragm.

[0011] Optionally, the positive electrode tab is welded at a first end in a width direction of the positive electrode sheet.

[0012] Optionally, the negative electrode tab is welded at an end of the negative electrode sheet that is away from the positive electrode tab in the width direction of the negative electrode sheet.

[0013] Optionally, the area where the positive tab is welded on the positive electrode sheet is the positive tab welding area, the length of the positive tab welding area is L1 mm, the width of the positive electrode sheet is W mm, and L1 and W satisfy the relationship: L1<1 / 2W.

[0014] Optionally, the area where the negative electrode tab is welded to the negative electrode sheet is the negative electrode tab welding area, the length of the negative electrode tab welding area projected onto the positive electrode sheet is L2 mm, and L2 and W satisfy the relationship: L2<1 / 2W.

[0015] Optionally, L1, L2, and W satisfy the relationship: L1+L2<W-2.

[0016] Another aspect of the present invention provides an electrical device, which includes the soft-pack cylindrical battery as described above.

[0017] According to the roll core provided by the present invention, by using silicon-based active materials as the negative electrode, the energy density of the battery cell is increased by more than 50% compared with graphite, and the battery energy density is significantly improved. At the same time, the positive electrode ear and the negative electrode ear are arranged at both ends of the roll core, and the positive electrode ear and the negative electrode ear are not on the same straight line. Therefore, when a large external force (such as ≥13KN) is applied to the surface of the roll core, since the positive electrode ear and the negative electrode ear are not on the same straight line, when the roll core undergoes a large axial deformation, the positive electrode ear and the negative electrode sheet are not easy to contact, which makes it difficult for the roll core to catch fire or explode, thereby improving the safety of batch application of the roll core. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of a soft-pack cylindrical battery in the prior art; Figure 2 is a schematic structural diagram of a soft-pack cylindrical battery provided by an embodiment of the present invention; Figure 3 1 is a schematic diagram of an expanded soft-pack cylindrical battery provided by an embodiment of the present invention; Figure 4 It is a schematic structural diagram of a negative electrode sheet in a soft-pack cylindrical battery provided by an embodiment of the present invention; Figure 5 This is a schematic diagram of a first structure in which a positive electrode tab is welded on a positive electrode sheet in a soft-pack cylindrical battery provided by an embodiment of the present invention; Figure 6 This is a schematic diagram of a second structure in which a positive electrode tab is welded on a positive electrode sheet in a soft-pack cylindrical battery provided by an embodiment of the present invention; Figure 7 This is a schematic diagram of a third structure in which a positive electrode tab is welded on a positive electrode sheet in a soft-pack cylindrical battery provided by an embodiment of the present invention; Figure 8 This is a schematic diagram of the area division on the electrode sheet in a soft-pack cylindrical battery provided by an embodiment of the present invention; The reference numerals in the drawings of the specification are as follows: 1-positive electrode sheet; 11-positive electrode ear; 2-negative electrode sheet; 21-negative electrode current collector; 22-negative electrode active material layer; 23-negative electrode ear; 3-diaphragm. DETAILED DESCRIPTION

[0019] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0020] In the description of the present invention, it should be understood that the terms "side", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0021] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0022] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods; the materials and reagents used are reagents and materials that can be obtained from commercial channels unless otherwise specified.

[0023] like Figure 2-Figure 4 As shown, in one embodiment, the present invention provides a soft-pack cylindrical battery, including a soft-pack shell (not shown in the figure) and a winding core arranged in the soft-pack shell, the winding core including a positive electrode sheet 1, a separator 3 and a negative electrode sheet 2; The negative electrode sheet 2 includes a negative electrode current collector 21 and negative electrode active material layers 22 disposed on both sides of the surface of the negative electrode current collector 21. The total thickness of the negative electrode active material layers 22 is 12 μm-20 μm. The negative electrode active material layer 22 includes a negative electrode silicon-based active material, the negative electrode silicon-based active material includes pure silicon particles, and the mass percentage of the pure silicon particles in the negative electrode silicon-based active material is 65-100%; The positive electrode sheet 1, the separator 3 and the negative electrode sheet 2 are stacked and wound to form a winding core, in which the positive electrode sheet 1 and the negative electrode sheet 2 are separated by the separator 3; the positive electrode sheet 1 is provided with a positive electrode ear 11, and the positive electrode ear 11 is located at the first end of the winding core, and the negative electrode sheet 2 is provided with a negative electrode ear 12, and the negative electrode ear 12 is located at the second end of the winding core, and the projection of the positive electrode ear 11 along the axial direction of the winding core on the end surface of the second end of the winding core does not intersect with the projection of the negative electrode ear 12 along the axial direction of the winding core on the end surface of the second end of the winding core.

[0024] Specifically, in one embodiment, negative electrode active material layers 22 are disposed on both sides of the surface of the negative electrode current collector 21 , and the total thickness of the negative electrode active material layers 22 is 12 μm-20 μm.

[0025] In order to better control the stability of the negative electrode silicon-based active material on the negative electrode current collector 21 during the battery operation process and improve the conductivity of the negative electrode silicon-based active material, the negative electrode silicon-based active material disposed on one side of the negative electrode current collector 21 of the negative electrode sheet 2 in the present invention is defined as the first negative electrode active material layer, and the negative electrode silicon-based active material disposed on the other side is defined as the second negative electrode active material layer. The sum of the thickness of the active material layer 22 is 12μm-20μm, that is, the sum of the thickness of the first negative electrode active material layer and the second negative electrode active material layer is 12μm-20μm. In other words, the thickness of the first negative electrode active material layer is 6μm-10μm; the thickness of the second negative electrode active material layer is 6μm-10μm. The sum of the thickness of the first negative electrode active material layer and the second negative electrode active material layer on the negative electrode sheet 2 is controlled between 12μm-20μm, so that the thickness of the negative electrode sheet 2 is much smaller than the thickness of the traditional negative electrode sheet 2.

[0026] Furthermore, the thickness of the negative electrode silicon-based active material on the negative electrode active material layer of the negative electrode sheet 2 provided by the present invention which is arranged on both sides of the negative electrode current collector 21 can be the same or different. The thickness of the negative electrode silicon-based active material of the negative electrode active material layer on one side can be adjusted separately as needed, or the thickness of the negative electrode silicon-based active material on both sides can be adjusted separately, but the sum of the thickness of the negative electrode active material layer 22 on both sides is still controlled between 12μm-20μm.

[0027] In order to better control the stability of the negative electrode silicon-based active material on the negative electrode current collector 21 during battery operation and improve the conductivity of the negative electrode silicon-based active material, negative electrode active material layers 22 are provided on both sides of the negative electrode sheet 2 in the present invention, and the sum of the thicknesses of the negative electrode active material layers 22 on both sides is controlled between 12μm and 20μm, so that the thickness of the negative electrode sheet 2 is much smaller than the thickness of the traditional negative electrode sheet 2.

[0028] Specifically, the mass percentage of pure silicon particles in the negative electrode silicon-based active material is 65%, 75%, 85%, 95% or 100% at any point or a range consisting of any two points. However, it is worth noting that 100% pure silicon is only discussed as a theoretical limit. In practical applications, since it is difficult for pure silicon to be completely free of impurities in its natural state, the so-called "100% pure silicon" does not actually exist. Even after a highly refined process, silicon materials will still contain trace amounts of impurity elements such as iron, aluminum, calcium, etc.

[0029] The negative electrode silicon-based active material provided by the present invention can be pure silicon, pure silicon and graphite, pure silicon and silicon-carbon material or silicon composite material. When the negative electrode silicon-based active material is pure silicon and graphite or pure silicon and silicon-carbon material or silicon composite material, the mass percentage of pure silicon in the negative electrode silicon-based active material is controlled at 65-100%. The present invention selects a negative electrode active material containing pure silicon particles, and the pure silicon particles have a very high theoretical specific capacity (up to 4200mAh / g), which far exceeds the theoretical specific capacity of traditional graphite negative electrodes (372mAh / g). Therefore, the use of a negative electrode active material containing pure silicon particles can significantly improve the energy density of the battery, so that the battery can store more electrical energy at the same weight or volume. In addition, compared with other high-performance negative electrode materials, the cost of pure silicon particles is relatively low, which makes it have potential cost advantages in large-scale commercial applications.

[0030] Using silicon-based active materials as the negative electrode, the energy density of the battery cell is increased by more than 50% compared to graphite. The higher the battery energy density, the worse the battery safety performance. Therefore, this application improves the existing battery structure to improve the battery safety performance.

[0031] like Figure 1 As shown, in the prior art, the positive electrode ear 11 and the negative electrode ear 23 in the soft-pack cylindrical battery are arranged at both ends of the winding core, and along the axial direction of the winding core, the extension line of the positive electrode ear 11 coincides with the negative electrode ear 23; when a large external force (such as ≥13KN) is applied to the surface of the winding core, the winding core will undergo a large deformation. Since the positive electrode ear 11 and the negative electrode ear 23 are located on the same straight line, when the winding core undergoes a large deformation, the positive electrode ear 11 and the negative electrode ear 23 are easily in contact with their corresponding negative electrode sheets and positive electrode sheets, thereby causing the winding core to catch fire or explode, posing a hidden danger to the mass application of the winding core.

[0032] like Figure 2 As shown, the positive electrode ear 11 and the negative electrode ear 23 of the present invention are arranged at both ends of the winding core, and along the axial direction of the winding core, the extension line of the positive electrode ear 11 does not overlap with the negative electrode ear 23; therefore, when a large external force (such as ≥13KN) is applied to the surface of the winding core, the positive electrode ear 11 and the negative electrode ear 23 are not on the same straight line, and the winding core is looser than the conventional structure. When the winding core undergoes a large deformation, the positive electrode ear 11 and the negative electrode ear 23 are not easy to contact with the corresponding negative electrode sheet 2 and positive electrode sheet 1, so it is not easy to cause the winding core to catch fire or explode, thereby improving the safety of batch application of the winding core.

[0033] The soft-pack cylindrical battery mentioned in the embodiments of the present application may be a single physical module including one or more core rolls to provide higher voltage and capacity. For example, the battery mentioned in the present application may include a core roll, a battery module or a battery pack, etc. The core roll is the smallest unit of the battery, which can realize the function of charging and discharging alone. When there are multiple core rolls, the multiple core rolls are connected in series, in parallel or in mixed connection through a busbar. In some embodiments, the battery may be a battery module; when there are multiple core rolls, the multiple core rolls are arranged and fixed to form a battery module. In some embodiments, the battery may be a battery pack, which includes a battery housing and a core roll, and the core roll or battery module is accommodated in the battery housing.

[0034] In some embodiments, the battery may be an energy storage device, which includes an energy storage container, an energy storage cabinet, and the like.

[0035] like Figure 4 As shown, in one embodiment, the thickness of the negative electrode sheet 2 is 18 μm-28 μm.

[0036] Specifically, the thickness of the negative electrode sheet 2 is any point value among 18μm, 19μm, 20μm, 21μm, 22μm, 23μm, 24μm, 25μm, 26μm, 27μm or 28μm, or a range value consisting of any two point values; in a preferred embodiment, the thickness of the negative electrode sheet 2 is 18μm-24μm.

[0037] The present invention can effectively shorten the transmission distance of electrons and lithium ions inside the electrode sheet by controlling the thickness of the negative electrode sheet 2 to be between 18 μm and 28 μm, which helps to reduce the internal resistance of the battery and improve the rate performance of the battery.

[0038] like Figure 4 As shown, in one embodiment, the double-sided surface density of the negative electrode sheet 2 is 1.6-2.4 mg / cm 2 ; The compaction density of the negative electrode sheet 2 is 1.1-1.3g / cm 3 .

[0039] Specifically, the double-sided surface density of the negative electrode sheet 2 is 1.6 mg / cm 2 、1.8mg / cm 2 , 2.0mg / cm 2 , 2.2mg / cm 2 or 2.4 mg / cm 2 In a preferred embodiment, the double-sided surface density of the negative electrode sheet 2 is 1.8 mg / cm 2 -2.2mg / cm 2 .

[0040] By optimizing the double-sided surface density of the negative electrode sheet 2, the thickness of the negative electrode sheet 2 can be regulated, the utilization rate of the negative electrode material can be improved, and thus the capacity and energy density of the battery can be increased.

[0041] When the surface density of both sides of the negative electrode sheet 2 is greater than 2.2 mg / cm 2 When the double-sided surface density of the negative electrode sheet 2 is less than 1.6 mg / cm, it means that more negative electrode active materials are loaded on the same area, which may theoretically increase the capacity of the battery. However, too high a surface density will increase the thickness of the negative electrode sheet 2, resulting in an increase in the internal resistance of the battery, affecting the charge and discharge efficiency of the battery, thereby limiting the improvement of the battery capacity to a certain extent. 2 Having less active material in the coating means that the number of lithium ions that can be stored and released during the charge and discharge process decreases, and the energy that can be stored per unit volume also decreases, so the battery capacity will also decrease.

[0042] Specifically, the compaction density of the negative electrode sheet 2 is 1.1 g / cm 3 , 1.15g / cm 3 , 1.2g / cm 3 , 1.25g / cm 3 or 1.3 g / cm 3 In a preferred embodiment, the compaction density of the negative electrode sheet 2 is 1.15 g / cm 3 -1.25g / cm 3 .

[0043] By controlling the compaction density of the negative electrode sheet 2, the porosity and void distribution of the negative electrode sheet 2 can be controlled, thereby adjusting the ion conduction capacity of the battery during the charge and discharge process, thereby changing the rate performance of the battery. When the compaction density of the negative electrode sheet 2 is greater than 1.30 g / cm 3 When the compaction density of the negative electrode sheet 2 is less than 1.10 g / cm 3 When the compaction density is too low, on the one hand, the active material in the negative electrode sheet 2 will be insufficiently filled, thereby reducing the capacity of the battery. On the other hand, it may also cause the voids inside the negative electrode sheet 2 to increase, thereby increasing the internal resistance of the battery and affecting the rate performance of the battery.

[0044] like Figure 2 As shown, in one embodiment, the projection of the positive electrode ear 11 on the second end surface of the winding core along the axial direction of the winding core and the projection of the negative electrode ear 12 on the second end surface of the winding core along the axial direction of the winding core are respectively located on both sides of the central axis of the winding core, and the positive electrode ear 11 is arranged in parallel with the negative electrode ear 12.

[0045] The positive electrode ear 11 and the negative electrode ear 23 of the present invention are arranged at both ends of the winding core, and the projection of the positive electrode ear 11 on the second end surface of the winding core and the negative electrode ear 12 are located on both sides of the central axis of the winding core and are arranged in parallel; therefore, when a large external force (such as ≥13KN) is applied to the surface of the winding core, the winding core is relatively loose, and the positive electrode ear 11 and the negative electrode ear 23 are not on the same side of the central axis. When the winding core undergoes a large deformation, the positive electrode ear 11 and the negative electrode ear 23 are not easy to contact with the corresponding positive and negative electrodes, so that it is not easy to cause the winding core to catch fire or explode, thereby improving the safety of batch application of the winding core.

[0046] like Figure 2 As shown, in one embodiment, the projection of the positive electrode tab 11 on the second end surface of the winding core along the axial direction of the winding core and the projection of the negative electrode tab 12 on the second end surface of the winding core along the axial direction of the winding core are symmetrically arranged about the central axis of the winding core.

[0047] The positive electrode ear 11 and the negative electrode ear 23 of the present invention are arranged at both ends of the winding core, and the projection of the positive electrode ear 11 on the second end surface of the winding core and the negative electrode ear 12 are symmetrically arranged about the central axis of the winding core; therefore, when a large external force (such as ≥13KN) is applied to the surface of the winding core, the winding core is relatively loose, and the positive electrode ear 11 and the negative electrode ear 23 are located on both sides of the central axis. When the winding core undergoes a large deformation, the positive electrode ear 11 and the negative electrode ear 23 are not easy to contact with the corresponding positive and negative electrodes, so that it is not easy to cause the winding core to catch fire or explode, thereby improving the safety of batch application of the winding core.

[0048] Furthermore, since the positive electrode ear 11 and the negative electrode ear 23 are symmetrically arranged about the center of the winding core, the lead-out position of the negative electrode ear 23 makes the force on the winding core in the width direction of the electrode ear or in the extrusion direction at a 45-degree angle to the width direction of the electrode ear more uniform, while reducing the maximum external force on the electrode ear locally in the width direction or in the extrusion direction at a 45-degree angle to the width direction of the electrode ear, and reducing the rate of increase of the reaction force in the direction perpendicular to the width direction of the electrode ear, so that during the extrusion process, the electrode piece will not be subjected to excessive pressure locally or to faster impact locally, resulting in the possibility of the electrode piece rupture, puncturing the diaphragm 3 and causing short circuit failure in the winding core, thereby ultimately making the winding core have good extrusion resistance.

[0049] In other embodiments, the connecting line of the centers of the two end surfaces of the winding core is used as the central axis, and the positive electrode ear 11 and the negative electrode ear 23 are respectively located on both sides of the central axis, so as to avoid that when the winding core undergoes a large deformation, the positive electrode ear 11 and the negative electrode ear 23 are not easy to contact with the corresponding negative electrode and positive electrode, thereby preventing the winding core from catching fire or exploding, thereby improving the safety of batch application of the winding core.

[0050] like Figure 3 As shown, the projection of the positive electrode sheet 1 on the separator 3 is located inside the projection of the negative electrode sheet 2 on the separator 3 .

[0051] In some embodiments, the positive electrode sheet 1 includes a positive electrode current collector and a positive electrode material layer coated on the surface of the positive electrode current collector, the positive electrode material layer includes a positive electrode active substance, the positive electrode active substance is not particularly limited, and any positive electrode active substance in the art can be used, for example, it can include at least one of lithium nickel cobalt manganese oxide (811, 622, 523, 111), lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium-rich manganese-based material, lithium cobalt oxide, lithium manganese oxide, lithium iron manganese phosphate or lithium titanate.

[0052] In some embodiments, the positive electrode material layer further includes a positive electrode conductive agent, and the type of the positive electrode conductive agent is not particularly limited as long as the purpose of the present application can be achieved. Examples of positive electrode conductive agents may include, but are not limited to, at least one of conductive carbon black (SuperP), carbon nanotubes (CNTs), carbon nanofibers, flake graphite, acetylene black, carbon black, Ketjen black, carbon dots or graphene, etc.; the above positive electrode conductive agents may be used alone or in any combination.

[0053] In some embodiments, the positive electrode material layer further includes a positive electrode binder. The type of the positive electrode binder is not particularly limited as long as it is a material that can be dissolved or dispersed in the liquid medium used in electrode manufacturing. Examples of positive electrode binders may include, but are not limited to, one or more of the following: resin polymers such as polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, polyimide, aromatic polyamide, cellulose, nitrocellulose, etc.; rubber polymers such as styrene-butadiene rubber, nitrile rubber, fluororubber, isoprene rubber, polybutadiene rubber, ethylene-propylene rubber, etc.; thermoplastic elastomer polymers such as styrene-butadiene-styrene block copolymers or their hydrides, ethylene-propylene-diene terpolymers, styrene-ethylene-butadiene-ethylene copolymers, styrene-isoprene-styrene block copolymers or their hydrides; soft resin polymers such as syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene-vinyl acetate copolymers, propylene-α-olefin copolymers, etc.; fluorine-based polymers such as polyvinylidene fluoride, polytetrafluoroethylene, fluorinated polyvinylidene fluoride, polytetrafluoroethylene-ethylene copolymers, etc.; polymer compositions having ion conductivity of alkali metal ions (especially lithium ions), etc. The above positive electrode binders may be used alone or in any combination.

[0054] In some embodiments, the type of solvent used to form the positive electrode slurry is not limited, as long as it is a solvent that can dissolve or disperse the positive electrode material, the conductive agent, the positive electrode binder, and the thickener used as needed. Examples of solvents used to form positive electrode slurries may include any of aqueous solvents and organic solvents. Examples of aqueous media may include, but are not limited to, water and mixed media of alcohol and water. Examples of organic media may include, but are not limited to, aliphatic hydrocarbons such as hexane; aromatic hydrocarbons such as benzene, toluene, xylene, methylnaphthalene; heterocyclic compounds such as quinoline and pyridine; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; esters such as methyl acetate and methyl acrylate; amines such as diethylenetriamine and N,N-dimethylaminopropylamine; ethers such as diethyl ether, propylene oxide, and tetrahydrofuran; amides such as N-methylpyrrolidone, dimethylformamide, and dimethylacetamide; aprotic polar solvents such as hexamethylphosphoramide and dimethyl sulfoxide, etc.

[0055] In some embodiments, the positive electrode material layer further includes a thickener. The thickener is generally used to adjust the viscosity of the slurry. In the case of using an aqueous medium, a thickener and a styrene-butadiene rubber emulsion can be used for slurrying. The type of thickener is not particularly limited, and examples thereof may include, but are not limited to, carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, and salts thereof. The above thickeners may be used alone or in any combination.

[0056] In some embodiments, the type of the positive electrode current collector is not particularly limited, and it can be any known material suitable for use as a positive electrode current collector. Examples of the positive electrode current collector can include, but are not limited to, aluminum.

[0057] In some embodiments, the negative electrode active material layer 22 further includes an auxiliary agent.

[0058] In some embodiments, the auxiliary agent includes a negative electrode conductive agent, which can also be selected from any type of conductive agent known to technicians in the field, and can be a combination of one or more of a branched conductive agent, a one-dimensional chain conductive agent, a two-dimensional flaky conductive agent, a polymer conductive agent, a carbon black conductive agent, and a graphite conductive agent. More preferably, it can be selected from one or more of superconducting carbon black, acetylene black, Ketjen black, carbon nanotubes, carbon fibers, flaky graphite, graphene, polyacetylene, polythiophene, polypyrrole, and polyaniline.

[0059] In some embodiments, the auxiliary agent may further include a negative electrode binder. The negative electrode binder can improve the bonding between the negative electrode material particles and the bonding between the negative electrode material and the current collector. The type of negative electrode binder is not particularly limited, as long as it is a material that is stable to the solvent used in the manufacture of the electrolyte or electrode. In some embodiments, the negative electrode binder includes a resin binder. Examples of resin binders include, but are not limited to, fluororesins, polyacrylonitrile (PAN), polyimide resins, acrylic resins, polyolefin resins, and the like. When an aqueous solvent is used to prepare the negative electrode mixture slurry, the negative electrode binder includes, but is not limited to, carboxymethyl cellulose (CMC) or its salt, styrene-butadiene rubber (SBR), polyacrylic acid (PAA) or its salt, polyvinyl alcohol, and the like.

[0060] In some embodiments, as the negative electrode current collector 21 for holding the negative electrode material, any known current collector may be used. Examples of the negative electrode current collector 21 include, but are not limited to, copper.

[0061] In some embodiments, there is no particular restriction on the material and shape of the diaphragm 3, as long as the effect of the present application is not significantly impaired. The diaphragm 3 may be a resin, glass fiber, inorganic material, etc. formed by a material that is stable to the electrolyte of the present application. In some embodiments, the diaphragm 3 includes a porous sheet or a non-woven fabric-like material with excellent liquid retention. Examples of materials for the resin or glass fiber diaphragm 3 may include, but are not limited to, polyolefins, aromatic polyamides, polytetrafluoroethylene, polyether sulfone, etc. In some embodiments, the polyolefin is polyethylene or polypropylene. In some embodiments, the polyolefin is polypropylene. The materials of the above-mentioned diaphragm 3 can be used alone or in any combination.

[0062] like Figure 5-7 As shown, in one embodiment, the positive electrode tab 11 is welded to the first end of the positive electrode sheet 1 in the width direction.

[0063] Specifically, along the length direction of the positive electrode sheet 1 , the positive electrode tab 11 is welded at the head end, the tail end or any position therebetween of the positive electrode sheet 1 .

[0064] like Figure 3 As shown, in one embodiment, the negative electrode tab 23 is welded to an end of the negative electrode sheet 2 in the width direction away from the positive electrode tab 11 .

[0065] Specifically, along the length direction of the negative electrode sheet 2 , the negative electrode ear 23 is welded at the head end, the tail end or any position therebetween of the negative electrode sheet 2 .

[0066] like Figure 3 As shown, in one embodiment, the area where the positive tab 11 is welded to the positive electrode sheet 1 is the positive tab welding area, the length of the positive tab welding area is L1 mm, the width of the positive electrode sheet 1 is W mm, and L1 and W satisfy the relationship: L1<1 / 2W.

[0067] like Figure 3 As shown, in one embodiment, the area where the negative electrode ear 23 is welded to the negative electrode sheet 2 is the negative electrode ear welding area, the length of the negative electrode ear welding area projected onto the positive electrode sheet 1 is L2 mm, the width of the positive electrode sheet 1 is W, and L2 and W satisfy the relationship: L2<1 / 2W.

[0068] Specifically, when L1<1 / 2W, L2<1 / 2W, along the direction perpendicular to the length of the core, the projections of the welding end of the positive ear 11 and the welding end of the negative ear 23 in the length direction of the core do not overlap. When a large external force (such as ≥13KN) is applied to the surface of the core, the core will undergo a large deformation, and the positive ear 11 and the negative ear 23 and their corresponding negative electrode sheet 2 and positive electrode sheet 1 are not easy to contact, which makes it difficult for the core to catch fire or explode, thereby improving the safety of mass application of the core.

[0069] like Figure 3 As shown, in one embodiment, L1, L2, and W satisfy the relationship: L1+L2<W-2.

[0070] Specifically, when L1+L2<W-2, along the direction perpendicular to the length of the core, the projections of the welding end of the positive electrode ear 11 and the welding end of the negative electrode ear 23 in the length direction of the core do not overlap. When a large external force (such as ≥13KN) is applied to the surface of the core, the core will undergo a large deformation. The positive electrode ear 11 and the negative electrode ear 23 are not easy to contact with their corresponding negative electrode sheet 2 and positive electrode sheet 1, which makes it difficult for the core to catch fire or explode, thereby improving the safety of mass application of the core.

[0071] Another aspect of the present invention provides an electrical device, which includes the soft-pack cylindrical battery as described above.

[0072] In another embodiment, the electrical device includes the soft-pack cylindrical battery provided in the present application. The soft-pack cylindrical battery can be used as a power source for the electrical device, or as an energy storage unit for the electrical device. The electrical device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited thereto.

[0073] As an electrical device, the number of soft-pack cylindrical batteries can be selected according to its usage requirements.

[0074] As an example of an electric device, the electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the electric device's requirements for high power and high energy density of secondary batteries, a battery pack or a battery module may be used.

[0075] As another example, the device may be an electronic cigarette, a mobile phone, a tablet computer, a laptop computer, etc. The device is usually required to be light and thin, and a secondary battery may be used as a power source.

[0076] In order to make the invention purpose, technical scheme and beneficial technical effect of the present invention clearer, the present invention is further described in detail below in conjunction with examples. However, it should be understood that the examples of the present invention are only for explaining the present invention, not for limiting the present invention, and the examples of the present invention are not limited to the examples given in the specification. The specific experimental conditions or operating conditions not specified in the examples are prepared under conventional conditions, or prepared under the conditions recommended by the material supplier.

[0077] In addition, it should be understood that one or more method steps mentioned in the present invention do not exclude the existence of other method steps before or after the combination step or the insertion of other method steps between these explicitly mentioned steps, unless otherwise specified; it should also be understood that the combination connection relationship between one or more devices / apparatuses mentioned in the present invention does not exclude the existence of other devices / apparatuses before or after the combination device / apparatus or the insertion of other devices / apparatuses between these explicitly mentioned two devices / apparatuses, unless otherwise specified. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or the scope of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the present invention without substantially changing the technical content.

[0078] In the following examples, the reagents, materials and instruments used, unless otherwise specified, can be purchased commercially or obtained by synthetic methods known in the art.

[0079] Embodiment 1: Cathode preparation: The binder PVDF 1.2% was fully stirred and mixed in an appropriate amount of NMP to form a PVDF glue solution; then 2.8% of the conductive agent was added to the PVDF glue solution for dispersion, and then 96% of the active material lithium cobalt oxide was added, and finally the viscosity was adjusted to form a uniform positive electrode slurry; the slurry was evenly coated on the positive electrode current collector aluminum foil, and the coating surface density was 13.2 mg / cm 2 After drying in the coating oven, it is rolled into a positive electrode strip with a compaction density of 3.77g / cm 3 , and then cut into positive electrode sheets of 734mm long and 28mm wide.

[0080] Negative electrode preparation: 0.8% CMC was added to deionized water and stirred, and then flake conductive carbon powder was added, followed by 2% polyacrylic acid binder, followed by 96% pure silicon, and finally 1.2% single-walled conductive carbon tube was added for dispersion, and then the viscosity was adjusted; a uniform negative electrode slurry was formed; the slurry was evenly coated on an 8μm thick negative electrode current collector copper foil, and the coating surface density was 1.6mg / cm 2 After drying in the coating oven, it is rolled into a negative electrode strip with a compaction density of 1.2g / cm 3 , and then cut into negative electrode sheets of 780 mm long and 29 mm wide, with a thickness of 20 μm.

[0081] Tab welding: Along the length direction of the positive electrode sheet, the positive electrode ear is welded at the head of the positive electrode sheet 1a area; the length of the positive electrode ear in the welding area of ​​the positive electrode sheet is L1, the width of the positive electrode sheet 1 is W, and L1 and W satisfy the relationship: L1<1 / 2W; Along the length direction of the negative electrode sheet, the negative electrode ear is welded at the head of the negative electrode sheet 1b area. The area where the negative electrode ear is welded to the negative electrode sheet is the negative electrode ear welding area. The length of the negative electrode ear welding area projected onto the positive electrode sheet is L2. The width of the positive electrode sheet is W. L2 and W satisfy the relationship: L2<1 / 2W; Preparation of electrolyte: Dissolve the lithium salt LiPF6 in a solvent, which uses a mixed solvent of EC / PC / DEC / EMC, and add additives such as VC, FEC, PS, etc. During the production process, the environmental humidity must be strictly controlled to prevent the introduction of moisture.

[0082] Preparation of soft-pack cylindrical batteries: The welded positive electrode sheet, separator and welded negative electrode sheet are stacked in order, so that the separator is in the middle of the positive and negative electrodes to play a role of isolation, and then rolled up from the first end of the positive electrode sheet along the length direction of the electrode sheet to form a bare battery cell. The bare battery cell is placed in a soft-pack shell, and then the ear glue and the soft-pack shell (aluminum-plastic film) are heat-sealed together, and then the electrolyte injection, high-temperature aging, formation, sealing and other processes are carried out to prepare a soft-pack cylindrical battery.

[0083] For the prepared battery cell, along the axis direction of the winding core, the projection of the positive electrode ear on the second end surface of the winding core and the projection of the negative electrode ear on the second end surface of the winding core are located on both sides of the central axis of the winding core and are nearly symmetrically arranged about the central axis of the winding core (with a deviation of less than 0.5 mm).

[0084] Example 2 Example 2 is used to illustrate a soft-pack cylindrical battery, a soft-pack cylindrical battery and an electric device disclosed in the present invention, and includes most of the operating steps in Example 1, except that: Tab welding: Along the length direction of the positive electrode sheet, the positive electrode ear is welded in the middle of the positive electrode sheet 2a area; Along the length direction of the negative electrode sheet, the negative electrode ear is welded in the middle of the negative electrode sheet 2b area.

[0085] In the prepared battery cell, along the axial direction of the winding core, the projection of the positive electrode ear on the second end surface of the winding core and the negative electrode ear are located on both sides of the central axis of the winding core and are nearly symmetrically arranged about the central axis of the winding core (with a deviation of less than 0.5 mm).

[0086] Example 3 Example 3 is used to illustrate a soft-pack cylindrical battery, a soft-pack cylindrical battery and an electric device disclosed in the present invention, and includes most of the operating steps in Example 1, except that: Tab welding: Along the length direction of the positive electrode sheet, the positive electrode ear is welded at the tail of the positive electrode sheet 3a area; Along the length direction of the negative electrode sheet, the negative electrode ear is welded at the tail of the negative electrode sheet 3b area.

[0087] In the prepared battery cell, along the axial direction of the winding core, the projection of the positive electrode ear on the second end surface of the winding core and the negative electrode ear are located on both sides of the central axis of the winding core and are nearly symmetrically arranged about the central axis of the winding core (with a deviation of less than 0.5 mm).

[0088] Example 4 Example 4 is used to illustrate a soft-pack cylindrical battery, a soft-pack cylindrical battery and an electrical device disclosed in the present invention, and includes most of the operating steps in Example 1, except that: Tab welding: Along the length direction of the positive electrode sheet, the positive electrode ear is welded to the head of the positive electrode sheet 1a area; Along the length direction of the negative electrode sheet, the negative electrode ear is welded to the head of the negative electrode sheet 2b area.

[0089] In the prepared battery cell, along the axis direction of the winding core, the projection of the positive electrode tab on the second end surface of the winding core and the negative electrode tab are located on both sides of the central axis of the winding core and are arranged in parallel; Example 5 Example 5 is used to illustrate a soft-pack cylindrical battery, a soft-pack cylindrical battery and an electric device disclosed in the present invention, and includes most of the operating steps in Example 1, except that: Tab welding: Along the length direction of the positive electrode sheet, the positive electrode ear is welded to the head of the positive electrode sheet 1a area; Along the length direction of the negative electrode sheet, the negative electrode ear is welded to the head of the negative electrode sheet 2a area.

[0090] In the prepared battery cell, along the axial direction of the winding core, the projection of the positive electrode ear on the second end surface of the winding core is located on the same side of the central axis as the negative electrode ear and does not intersect.

[0091] Comparative Example 1 Comparative Example 1 is used to illustrate a soft-pack cylindrical battery, a soft-pack cylindrical battery and an electric device disclosed in the present invention, and includes most of the operating steps in Example 1, except that: Tab welding: Along the length direction of the positive electrode sheet, the positive electrode ear is welded to the head of the positive electrode sheet 1a area; Along the length direction of the negative electrode sheet, the negative electrode ear is welded to the head of the negative electrode sheet 1a.

[0092] In the prepared battery cell, along the axial direction of the winding core, the projection of the positive electrode ear on the second end surface of the winding core is almost overlapped with the negative electrode ear (with a deviation of less than 0.5 mm).

[0093] Comparative Example 2 Comparative Example 2 is used to illustrate a soft-pack cylindrical battery, a soft-pack cylindrical battery and an electrical device disclosed in the present invention, and includes most of the operating steps in Example 1, except that: Tab welding: Along the length direction of the positive electrode sheet, the positive electrode ear is welded in the middle of the positive electrode sheet 2a area; Along the length direction of the negative electrode sheet, the negative electrode ear is welded in the middle of the negative electrode sheet 2a area.

[0094] In the prepared battery cell, along the axial direction of the winding core, the projection of the positive electrode ear on the second end surface of the winding core is almost overlapped with the negative electrode ear (with a deviation of less than 0.5 mm).

[0095] Comparative Example 3 Comparative Example 3 is used to illustrate a soft-pack cylindrical battery, a soft-pack cylindrical battery and an electrical device disclosed in the present invention, and includes most of the operating steps in Example 1, except that: Tab welding: Along the length direction of the positive electrode sheet, the positive electrode ear is welded at the tail of the positive electrode sheet 3a area; Along the length direction of the negative electrode sheet, the negative electrode ear is welded at the tail of the negative electrode sheet 3a area.

[0096] In the prepared battery cell, along the axial direction of the winding core, the projection of the positive electrode ear on the second end surface of the winding core is almost overlapped with the negative electrode ear (with a deviation of less than 0.5 mm).

[0097] Comparative Example 4 Comparative Example 4 is used to illustrate a soft-pack cylindrical battery, a soft-pack cylindrical battery and an electric device disclosed in the present invention, including most of the operating steps in Example 1, except that: The length of the positive electrode ear in the welding area of ​​the positive electrode sheet is L1, the width of the positive electrode sheet 1 is W, and L1 and W satisfy the relationship: L1>1 / 2W; The area where the negative electrode ear is welded to the negative electrode sheet is the negative electrode ear welding area. The length of the negative electrode ear welding area projected onto the positive electrode sheet is L2. The width of the positive electrode sheet is W. L2 and W satisfy the relationship: L2>1 / 2W. The prepared battery cell, along the axis direction of the winding core, the projection of the positive electrode ear on the second end surface of the winding core and the negative electrode ear are located on both sides of the central axis of the winding core and are symmetrically arranged about the central axis of the winding core; Along a direction perpendicular to the axis of the winding core, a projection of the positive electrode tab in the axial direction of the winding core partially overlaps with a projection of the negative electrode tab in the axial direction of the winding core.

[0098] Comparative Example 5 Comparative Example 5 is used to illustrate a soft-pack cylindrical battery, a soft-pack cylindrical battery and an electric device disclosed in the present invention, including most of the operating steps in Example 1, except that: Tab welding: Along the length direction of the positive electrode sheet, the positive electrode ear is welded at the head of the positive electrode sheet 1a area; the length of the positive electrode ear in the welding area of ​​the positive electrode sheet is L1, and the width of the positive electrode sheet 1 is W, and L1 and W satisfy the relationship: L1>1 / 2W; Along the length direction of the negative electrode sheet, the negative electrode ear is welded at the head of the negative electrode sheet 2b area; the area where the negative electrode ear is welded to the negative electrode sheet is the negative electrode ear welding area, the length of the negative electrode ear welding area projected onto the positive electrode sheet is L2, the width of the positive electrode sheet is W, and L2 and W satisfy the relationship: L2>1 / 2W; In the prepared battery cell, along the axis direction of the winding core, the projection of the positive electrode tab on the second end surface of the winding core and the negative electrode tab are located on both sides of the central axis of the winding core and are arranged in parallel; Along a direction perpendicular to the axis of the winding core, a projection of the positive electrode tab in the axial direction of the winding core partially overlaps with a projection of the negative electrode tab in the axial direction of the winding core.

[0099] Comparative Example 6 Comparative Example 6 is used to illustrate a soft-pack cylindrical battery, a soft-pack cylindrical battery and an electrical device disclosed in the present invention, and includes most of the operating steps in Example 1, except that: Tab welding: Along the length direction of the positive electrode sheet, the positive electrode ear is welded at the head of the positive electrode sheet 1a area; the length of the positive electrode ear in the welding area of ​​the positive electrode sheet is L1, and the width of the positive electrode sheet 1 is W, and L1 and W satisfy the relationship: L1>1 / 2W; Along the length direction of the negative electrode sheet, the negative electrode ear is welded at the head of the negative electrode sheet 2a area; the area where the negative electrode ear is welded to the negative electrode sheet is the negative electrode ear welding area, the length of the negative electrode ear welding area projected onto the positive electrode sheet is L2, the width of the positive electrode sheet is W, and L2 and W satisfy the relationship: L2>1 / 2W; In the prepared battery cell, along the axis direction of the winding core, the projection of the positive electrode ear on the second end surface of the winding core does not intersect with the negative electrode ear; Along a direction perpendicular to the axis of the winding core, a projection of the positive electrode tab in the axial direction of the winding core partially overlaps with a projection of the negative electrode tab in the axial direction of the winding core.

[0100] Comparative Example 7 Comparative Example 7 is used to illustrate a soft-pack cylindrical battery, a soft-pack cylindrical battery and an electric device disclosed in the present invention, including most of the operating steps in Example 1, except that: Tab welding: The length of the positive electrode ear in the welding area of ​​the positive electrode sheet is L1, the width of the positive electrode sheet 1 is W, and L1 and W satisfy the relationship: L1=1 / 2W; The area where the negative electrode ear is welded to the negative electrode sheet is the negative electrode ear welding area. The length of the negative electrode ear welding area projected onto the positive electrode sheet is L2. The width of the positive electrode sheet is W. L2 and W satisfy the relationship: L2=1 / 2W. In the prepared battery cell, along the axial direction of the core, the projection of the positive electrode ear on the second end face of the core and the negative electrode ear are located on both sides of the central axis of the core and are symmetrically arranged about the central axis of the core; along the axial direction perpendicular to the core, the projection of the positive electrode ear in the axial direction of the core abuts against the projection of the negative electrode ear in the axial direction of the core.

[0101] Performance Test: Extrusion test: Test method: 15 soft-pack lithium-ion batteries prepared in Examples 1-5 and Comparative Examples 1-7 were prepared, and an extrusion test was performed on a 13KN press; The test results are shown in Table 1: Table 1 Extrusion test results of Examples 1-5 of the present invention and Comparative Examples 1-6 As can be seen from Table 1, the soft-pack cylindrical batteries prepared in Examples 1-5 of the present invention can still be maintained during the extrusion process under a pressure of 13KN, and no internal short circuit occurs in the positive and negative electrodes, and 100% pass the extrusion test; Comparative Examples 1-3 use the existing soft-pack cylindrical battery structure. Under the pressure of 13KN, the positive and negative electrodes will be locally overstressed, causing the pole pieces to rupture, and then the diaphragm will be damaged, causing an internal short circuit in the battery cell. In severe cases, the battery cell will catch fire and explode; For the soft-pack cylindrical batteries prepared in Comparative Examples 4-7, although the projection of the positive electrode ear on the second end face of the core does not intersect with the negative electrode ear along the axial direction of the core; however, along the axial direction perpendicular to the core, the projection of the positive electrode ear in the axial direction of the core abuts against the projection of the negative electrode ear in the axial direction of the core, and it will also deform under the pressure of 13KN; this is because the lead-out of the negative electrode ear makes the force on the core in the width direction of the ear or in the direction of extrusion at an acute angle to the width direction of the ear more uniform, reducing the maximum external force locally applied to the ear during the process of extrusion in the width direction or in the direction of extrusion at an acute angle to the width direction of the ear, and at the same time reducing the rate of increase of the reaction force in the direction perpendicular to the width direction of the ear, so that the electrode sheet will not be subjected to excessive pressure locally during the extrusion process, or will not be subjected to faster impact locally, resulting in the possibility of the electrode sheet rupturing, puncturing the diaphragm, and causing short circuit failure in the core, and ultimately making the core have good extrusion resistance.

[0102] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A soft-pack cylindrical battery, characterized in that: It includes a soft-package shell and a winding core arranged in the soft-package shell, wherein the winding core includes a positive electrode sheet, a separator and a negative electrode sheet; The negative electrode sheet comprises a negative electrode current collector and negative electrode active material layers disposed on both sides of the surface of the negative electrode current collector, and the total thickness of the negative electrode active material layers is 12 μm-20 μm; The negative electrode active material layer includes a negative electrode silicon-based active material, the negative electrode silicon-based active material includes pure silicon particles, and the mass percentage of the pure silicon particles in the negative electrode silicon-based active material is 65-100%; The positive electrode sheet, the separator and the negative electrode sheet are stacked and wound to form the winding core, in which the positive electrode sheet and the negative electrode sheet are separated by the separator; the positive electrode sheet is provided with a positive electrode ear, and the positive electrode ear is located at the first end of the winding core; the negative electrode sheet is provided with a negative electrode ear, and the negative electrode ear is located at the second end of the winding core; the projection of the positive electrode ear on the end surface of the second end of the winding core along the axial direction of the winding core does not intersect with the projection of the negative electrode ear on the end surface of the second end of the winding core along the axial direction of the winding core.

2. The soft-pack cylindrical battery according to claim 1, characterized in that: The thickness of the negative electrode sheet is 18 μm-28 μm.

3. The soft-pack cylindrical battery according to claim 1, characterized in that: The double-sided surface density of the negative electrode sheet is 1.6-2.4 mg / cm 2 The compaction density of the negative electrode sheet is 1.1-1.3 g / cm 3 .

4. The soft-pack cylindrical battery according to any one of claims 1 to 3, characterized in that: The projection of the positive electrode ear on the second end surface of the winding core along the axial direction of the winding core and the projection of the negative electrode ear on the second end surface of the winding core along the axial direction of the winding core are respectively located on both sides of the central axis of the winding core, and the positive electrode ear is arranged in parallel with the negative electrode ear.

5. The soft-pack cylindrical battery according to claim 4, characterized in that: The projection of the positive electrode tab on the second end surface of the winding core along the axis direction of the winding core and the projection of the negative electrode tab on the second end surface of the winding core along the axis direction of the winding core are symmetrically arranged about the central axis of the winding core.

6. The soft-pack cylindrical battery according to claim 1, characterized in that: The projection of the positive electrode sheet on the diaphragm is located inside the projection of the negative electrode sheet on the diaphragm.

7. The soft-pack cylindrical battery according to claim 1, characterized in that: The positive electrode tab is welded at one end of the positive electrode sheet in the width direction.

8. The soft-pack cylindrical battery according to claim 7, characterized in that: The negative electrode tab is welded at an end of the negative electrode sheet in the width direction away from the positive electrode tab.

9. The soft-pack cylindrical battery according to claim 8, characterized in that: The area where the positive electrode tab is welded to the positive electrode sheet is the positive electrode tab welding area. The length of the positive electrode tab welding area is L1 mm, the width of the positive electrode sheet is W mm, and L1 and W satisfy the relationship: L1<1 / 2W.

10. The soft-pack cylindrical battery according to claim 9, characterized in that: The area where the negative electrode tab is welded to the negative electrode sheet is the negative electrode tab welding area. The length of the negative electrode tab welding area projected onto the positive electrode sheet is L2 mm. L2 and W satisfy the relationship: L2<1 / 2W.

11. The soft-package cylindrical battery according to claim 10, characterized in that: The L1, L2, and W satisfy the relationship: L1+L2<W-2.

12. An electrical device, characterized in that: The electrical device comprises a soft-pack cylindrical battery as described in any one of claims 1-11.

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