Safety battery and electric device

Abstract

The invention belongs to the technical field of batteries, and relates to a safety type battery and an electric device, the safety type battery adopts a safety type current collector, and the safety type current collector comprises a base film layer and a metal layer arranged on at least one side surface of the base film layer; before the safe current collector is not coated with the active material, the bonding strength between the base film layer and the metal layer is greater than or equal to 300N / m; after the safe current collector is assembled into a battery cell and is subjected to formation treatment, the bonding strength between the base film layer and the metal layer is 0; wherein the single-layer thickness of the metal layer is less than or equal to 2 microns. According to the safe battery provided by the invention, when the interior of the battery is inflated, the base film layer and the metal layer are quickly layered, and the metal layer is ultra-thin and generates cracks under external force, so that the performance of the battery is quickly attenuated, and the safety early warning function of the battery is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of batteries, and relates to a safe battery, and particularly to a safe battery and an electrical device. Background Art

[0002] At present, functional current collectors based on polymer membranes have received extensive attention and applications in the new energy industry. Compared with traditional current collectors (such as copper foils), functional current collectors based on polymer membranes have many advantages such as low cost, light weight, and good internal insulation. These advantages enable the functional current collector to significantly reduce the manufacturing cost of the battery when applied in the battery, while improving the energy density and safety performance of the battery.

[0003] However, after the functional current collector is applied to the battery, it can only fully play its safety protection role when the battery is subjected to a huge external force collision. Under normal working conditions, this safety characteristic of the functional current collector may not be obvious. For example, when the hydrogen concentration inside the battery exceeds 4%, it may trigger an explosion once it comes into contact with a fire source; overcharging will cause excessive gas to be generated inside the battery, and if it cannot be discharged in time, the risk of explosion will increase. In addition, when the battery plate of the storage battery becomes sulfided, the single-cell voltage and the electrolyte temperature during the charging process will rise rapidly, which is extremely likely to cause the battery to expand or even explode.

[0004] In short, the existing technology still cannot effectively reduce the safety risks during the daily use of the battery. Although the functional current collector can provide additional safety protection when subjected to an external force collision, there are still obvious deficiencies in other aspects (such as hydrogen concentration control, overcharging protection, and sulfidation prevention). It is urgent to further optimize the design of its structure and material to achieve a comprehensive improvement in safety performance. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a safe battery and an electrical device. When the safe battery encounters internal gas swelling in the battery, through the rapid delamination between the base film layer and the metal layer and the ultra-thin thickness of the metal layer, cracks are generated when subjected to an external force, so that the battery performance decays rapidly, thereby realizing the safety warning function of the battery.

[0006] To achieve the purpose of this invention, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a safe battery, and the safe battery adopts a safe current collector, and the safe current collector includes a base film layer and a metal layer provided on at least one surface of the base film layer.

[0008] Before the safety current collector is coated with active materials, the bonding strength between the base film layer and the metal layer is ≥300 N / m; after the safety current collector is assembled into an electric core and undergoes formation treatment, the bonding strength between the base film layer and the metal layer is 0.

[0009] Among them, the single-layer thickness of the metal layer is ≤2 μm.

[0010] For ultra-thin metal foils, when preparing them into electrode sheets, since it is necessary to coat active materials on the surface of the metal foil and perform rolling, this process will exert great mechanical stress on the metal foil, which is extremely likely to cause damage to the ultra-thin metal foil. Such damage will not only have an adverse impact on the quality and performance of the electrode sheet, but also increase production costs and process complexity. Before the safety current collector provided by the present invention is assembled into an electric core, the metal layer is combined with the base film layer, which not only ensures the mechanical properties of the current collector, but also the base film layer can effectively disperse the concentrated stress generated during rolling as a support layer, thus avoiding excessive local stress on the metal layer and ensuring the integrity of the metal layer before delamination during formation.

[0011] When encountering gas swelling inside the battery, since the bonding strength between the base film layer and the metal layer is 0, rapid delamination can be achieved, and the thickness of the metal layer is ultra-thin (less than 2 μm), and cracks are easily generated when subjected to external forces, resulting in a rapid decline in battery performance. Users can accurately judge whether there is a safety risk inside the battery in a timely manner according to the decline in battery performance, thus realizing the safety warning function of the battery.

[0012] Preferably, a functional layer is further provided on at least one surface of the base film layer.

[0013] Preferably, the material of the functional layer includes acrylate and vinyl ethylene carbonate.

[0014] Preferably, the mass ratio of acrylate to vinyl ethylene carbonate is 1:(0.2 - 0.5).

[0015] Preferably, inorganic particles are included inside the base film layer.

[0016] Preferably, the Mohs hardness of the inorganic particles is ≥4.

[0017] Preferably, based on the total mass of the base film layer as the calculation benchmark, the content of the inorganic particles is 0.5% - 5%.

[0018] Preferably, the material of the inorganic particles includes any one or a combination of at least two of silicon dioxide, titanium dioxide, aluminum oxide, magnesium oxide, or iron phosphate.

[0019] Preferably, a lithium supplement agent is further included inside the base film layer, and the lithium supplement agent includes any one or a combination of at least two of lithium hydroxide, lithium-rich nickelate, lithium-rich ironate, lithium-rich oxalate, lithium-rich manganate, or lithium-rich cobaltate.

[0020] Preferably, the material of the base film layer includes any one or a combination of at least two of polypropylene, polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyimide, polypropylene, polyvinyl chloride, polyvinylidene fluoride, polytetrafluoroethylene, polyphenylene sulfide, polyphenylene ether, polystyrene, or polyamide.

[0021] Preferably, the thickness of the base film layer is 1-10 μm.

[0022] Preferably, the material of the metal layer includes any one of titanium, silver, aluminum, aluminum alloy, nickel, nickel alloy, copper, or copper alloy.

[0023] Preferably, the single-layer thickness of the metal layer is 0.8-1.2 μm.

[0024] Preferably, an underlayer is provided between the base film layer and the metal layer.

[0025] Preferably, one side surface of the underlayer close to the metal layer has a texture structure, and after the metal layer is delaminated, the underlayer adheres to the surface of the metal layer.

[0026] Preferably, taking the single-side area of the underlayer as the calculation reference, the area ratio of the texture structure is 20%-80%.

[0027] Preferably, the material of the underlayer includes any one of nickel-chromium alloy, alumina, silica, titanium oxide, elemental nickel, elemental chromium, elemental titanium, nickel-chromium-copper alloy, or silicon-aluminum alloy.

[0028] Preferably, the porosity of the functional layer ≤ 40%.

[0029] Preferably, the single-layer thickness of the functional layer is 20-2000 nm.

[0030] Preferably, a protective layer is further provided on at least one side surface of the safety-type current collector.

[0031] Preferably, the material of the protective layer includes any one of nickel, nickel oxide, nickel-based alloy, chromium, chromium oxide, copper oxide, copper-based alloy, alumina, silica, cobalt oxide, graphite, carbon black, copper chromate, cuprous chromite, carbon nano quantum dots, carbon nanotubes, carbon nanofibers, graphene, or fluorinated hydrocarbons.

[0032] Preferably, the single-layer thickness of the protective layer is 10-100 nm.

[0033] In a second aspect, the present invention provides an electrical device, which includes the safety-type battery as described in the first aspect.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] (1) Before the safety-type current collector provided by the present invention is assembled into an electrode core, the metal layer is combined with the base film layer, which not only ensures the mechanical properties of the current collector, but also the base film layer, as a support layer, can effectively disperse the concentrated stress generated during rolling, thereby avoiding excessive local stress on the metal layer and ensuring the integrity of the metal layer before formation delamination.

[0036] (2) When the battery bulges inside, since the bonding strength between the base film layer and the metal layer is 0, rapid delamination can be achieved, and the thickness of the metal layer is ultra-thin (less than 2 μm), and cracks are likely to occur when subjected to external forces, causing the battery performance to rapidly decay. The user can accurately judge whether there is a safety risk inside the battery in a timely manner according to the decay of the battery performance, thereby realizing the safety warning function of the battery. Specific Embodiments

[0037] The technical solutions of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0038] An embodiment of the present invention provides a safety-type battery, which uses a safety-type current collector. The safety-type current collector includes a base film layer and a metal layer provided on at least one surface of the base film layer.

[0039] Before the safety-type current collector is coated with active materials, the bonding strength between the base film layer and the metal layer is ≥300 N / m. For example, it can be 300 N / m, 350 N / m, 400 N / m, 450 N / m, 500 N / m, 550 N / m, 600 N / m, 650 N / m, 700 N / m, 750 N / m, 800 N / m, 900 N / m, 1000 N / m, 1100 N / m or 1200 N / m; after the safety-type current collector is assembled into an electrode core and undergoes formation treatment, the bonding strength between the base film layer and the metal layer is 0.

[0040] Among them, the single-layer thickness of the metal layer is ≤2 μm. For example, it can be 0.2 μm, 0.4 μm, 0.6 μm, 0.8 μm, 1 μm, 1.2 μm, 1.4 μm, 1.6 μm, 1.8 μm or 2 μm, but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0041] For ultra-thin metal foils, when preparing them into electrode sheets, since it is necessary to coat active materials on the surface of the metal foils and perform rolling, this process will exert great mechanical stress on the metal foils, which is extremely likely to cause damage to the ultra-thin metal foils. Such damage will not only have an adverse impact on the quality and performance of the electrode sheets, but also increase the production cost and process complexity. Before the safety current collector provided by the present invention is assembled into an electric core, the metal layer is combined with the base film layer, which not only ensures the mechanical properties of the current collector, but also the base film layer, as a support layer, can effectively disperse the concentrated stress generated during rolling, thereby avoiding excessive local stress on the metal layer and ensuring the integrity of the metal layer before the formation and layering process.

[0042] When encountering gas swelling inside the battery, since the bonding strength between the base film layer and the metal layer is 0, rapid delamination can be achieved, and the thickness of the metal layer is ultra-thin (less than 2 μm), and cracks are easily generated when subjected to external forces, causing the battery performance to rapidly decay. Users can accurately judge whether there is a safety risk inside the battery according to the decay of the battery performance in a timely manner, thus realizing the safety warning function of the battery.

[0043] In some embodiments, a functional layer is further provided on at least one surface of the base film layer.

[0044] In some embodiments, the material of the functional layer includes acrylate and vinyl ethylene carbonate.

[0045] In some embodiments, the mass ratio of the acrylate to the vinyl ethylene carbonate is 1:(0.2 - 0.5), for example, it can be 1:0.2, 1:0.25, 1:0.3, 1:0.35, 1:0.4, 1:0.45 or 1:0.5, but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0046] In some embodiments, inorganic particles are included inside the base film layer.

[0047] In some embodiments, the Mohs hardness of the inorganic particles is ≥4, for example, it can be 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5 or 8, but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0048] By adding inorganic particles with a specific hardness inside the base film layer in the present invention, not only can the mechanical properties, surface roughness and thermal stability of the base film layer be ensured, which is beneficial to the industrialization of the safety current collector, but also the wetting effect of the electrolyte on the metal layer after delamination can be improved, and the chemical erosion of the electrolyte on the base film layer can be reduced.

[0049] In some embodiments, based on the total mass of the base film layer, the content of the inorganic particles is 0.5% - 5%, for example, it can be 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5%, but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0050] In some embodiments, the material of the inorganic particles includes any one or a combination of at least two of silica, titanium dioxide, alumina, magnesia or iron phosphate. Typical but non - limiting combinations include the combination of silica and titanium dioxide, the combination of titanium dioxide and alumina, the combination of alumina and magnesia, or the combination of magnesia and iron phosphate.

[0051] In some embodiments, the interior of the base film layer further contains a lithium supplement agent, and the lithium supplement agent includes any one or a combination of at least two of lithium hydroxide, lithium - rich lithium nickelate, lithium - rich lithium ferrate, lithium - rich lithium oxalate, lithium - rich lithium manganate or lithium - rich lithium cobaltate. Typical but non - limiting combinations include the combination of lithium hydroxide and lithium - rich lithium nickelate, the combination of lithium - rich lithium nickelate and lithium - rich lithium ferrate, the combination of lithium - rich lithium ferrate and lithium - rich lithium oxalate, the combination of lithium - rich lithium oxalate and lithium - rich lithium manganate, or the combination of lithium - rich lithium manganate and lithium - rich lithium cobaltate.

[0052] By adding a lithium supplement agent inside the base film layer in the present invention, the mechanical properties of the base film layer can be improved and the function of timed lithium supplementation can be realized by adjusting the material components and ratios to balance high adhesion and lithium supplementation effect.

[0053] In some embodiments, the material of the base film layer includes any one or a combination of at least two of polypropylene, polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyimide, polypropylene styrene, polyvinyl chloride, polyvinylidene fluoride, polytetrafluoroethylene, polyphenylene sulfide, polyphenylene ether, polystyrene or polyamide. Typical but non - limiting combinations include the combination of polypropylene and polyethylene, the combination of polyethylene and polyethylene terephthalate, the combination of polyethylene terephthalate and polybutylene terephthalate, the combination of polybutylene terephthalate and polyethylene naphthalate, the combination of polyethylene naphthalate and polyimide, the combination of polyimide and polypropylene styrene, the combination of polypropylene styrene and polyvinyl chloride, the combination of polyvinyl chloride and polyvinylidene fluoride, the combination of polyvinylidene fluoride and polytetrafluoroethylene, the combination of polytetrafluoroethylene and polyphenylene sulfide, the combination of polyphenylene sulfide and polyphenylene ether, the combination of polyphenylene ether and polystyrene, or the combination of polystyrene and polyamide.

[0054] In some embodiments, the thickness of the base film layer is 1-10 μm, for example, it can be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm, but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0055] In some embodiments, the material of the metal layer includes any one of titanium, silver, aluminum, aluminum alloy, nickel, nickel alloy, copper or copper alloy.

[0056] In some embodiments, the single-layer thickness of the metal layer is 0.8-1.2 μm, for example, it can be 0.8 μm, 0.9 μm, 1 μm, 1.1 μm or 1.2 μm, but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0057] In some embodiments, an underlayer is provided between the base film layer and the metal layer.

[0058] In some embodiments, one side surface of the underlayer close to the metal layer has a texture structure, and after the metal layer is delaminated, the underlayer adheres to the surface of the metal layer.

[0059] In the present invention, an underlayer with a texture structure is provided between the base film layer and the metal layer, and the texture structure is close to the metal layer, which enhances the bonding force between the underlayer and the metal layer, and this bonding force is higher than the bonding force between the base film layer and the underlayer, thereby ensuring the effective separation of the metal layer and the base film layer. At the same time, the texture structure speeds up the infiltration speed of the electrolyte, thereby accelerating the erosion effect of the electrolyte.

[0060] In the present invention, the structural unit of the texture structure can be any one of a wavy line, a broken line, a straight line or a dotted line, as long as it belongs to the category of the texture structure, so no special limitation is made on its specific structural details here.

[0061] In some embodiments, based on the unilateral area of the underlayer as the calculation benchmark, the area ratio of the texture structure is 20%-80%, for example, it can be 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75% or 80%, but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0062] In some embodiments, the material of the underlayer includes any one of nickel-chromium alloy, aluminum oxide, silicon oxide, titanium oxide, elemental nickel, elemental chromium, elemental titanium, nickel-chromium-copper alloy or silicon-aluminum alloy.

[0063] In some embodiments, the porosity of the functional layer is ≤ 40%, for example, it can be 5%, 10%, 15%, 20%, 25%, 30%, 35% or 40%, but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0064] In some embodiments, the single-layer thickness of the functional layer is 20 - 2000 nm, for example, it can be 20 nm, 100 nm, 200 nm, 400 nm, 600 nm, 800 nm, 1000 nm, 1200 nm, 1400 nm, 1600 nm, 1800 nm or 2000 nm, but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0065] In some embodiments, a protective layer is further provided on at least one surface of the safety current collector.

[0066] In some embodiments, the material of the protective layer includes any one of nickel, nickel oxide, nickel-based alloy, chromium, chromium oxide, copper oxide, copper-based alloy, aluminum oxide, silicon oxide, cobalt oxide, graphite, carbon black, copper chromate, cuprous chromite, carbon nano quantum dots, carbon nanotubes, carbon nanofibers, graphene or fluorinated hydrocarbons.

[0067] In some embodiments, the single-layer thickness of the protective layer is 10 - 100 nm, for example, it can be 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm or 100 nm, but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0068] An embodiment of the present invention further provides an electrical device, and the electrical device includes the safety battery as described in any one of the above embodiments.

[0069] The numerical ranges described in the present invention include not only the above-listed point values, but also any point values between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the ranges.

[0070] Example 1

[0071] This example provides a safety battery, and the safety battery uses a safety current collector. The specific preparation method of the safety current collector is as follows:

[0072] Mix acrylate and vinyl ethylene carbonate in a mass ratio of 1:0.3, and coat the resulting mixture on both side surfaces of a PET film (with a thickness of 6 μm) to form a functional layer; then dry it at 60 °C for 5 min, at 80 °C for 3 min, and at 100 °C for 1 min in sequence. After drying, the single-layer thickness of the functional layer is 100 nm and the porosity is 0; place the film with the functional layer in the chamber of vacuum evaporation, melt and evaporate the high-purity copper wire (with a purity greater than 99.99%) in the metal evaporation chamber at a high temperature of 1500 °C. The evaporated copper atoms pass through the cooling system in the vacuum coating chamber and are deposited on the two opposite side surfaces of the film to form a metal layer with a single-layer thickness of 1 μm.

[0073] The preparation method of the safety battery provided in this embodiment includes the following steps:

[0074] (1) Use an aluminum foil with a thickness of 12 μm as the positive current collector, and use lithium iron phosphate (LiFePO4) as the positive electrode material;

[0075] (2) Use the above-mentioned safety current collector as the negative current collector, and use graphite as the negative electrode material;

[0076] (3) Use a carbonate solution of 1M lithium hexafluorophosphate (LiPF6), and select a combination of propylene carbonate, ethylene carbonate, and ethyl methyl carbonate with a mass ratio of 1:1:1 as the carbonate solvent;

[0077] (4) Stack the positive and negative electrode plates and the separator in sequence and wind them into a cylindrical core, bake them after putting them into the shell, inject the electrolyte into the core and seal the cover plate, and obtain a safety battery after formation.

[0078] Example 2

[0079] This embodiment provides a safety battery. Except for adding titanium dioxide particles (with an average particle size of 30 nm and a Mohs hardness of 7) to the PET film, and taking the total mass of the PET film as the calculation basis, the content of the titanium dioxide particles is 1%, the rest of the steps and conditions are the same as those in Example 1, so they will not be elaborated here.

[0080] Example 3

[0081] This embodiment provides a safety battery. Except for replacing the titanium dioxide particles with silicon dioxide particles (with an average particle size of 30 nm and a Mohs hardness of 7), the rest of the steps and conditions are the same as those in Example 2, so they will not be elaborated here.

[0082] Example 4

[0083] This embodiment provides a safe battery. Except that the content of titanium dioxide particles is changed to 0.5%, the remaining steps and conditions are the same as those in Embodiment 2, so they will not be elaborated here.

[0084] Embodiment 5

[0085] This embodiment provides a safe battery. Except that the content of titanium dioxide particles is changed to 5%, the remaining steps and conditions are the same as those in Embodiment 2, so they will not be elaborated here.

[0086] Embodiment 6

[0087] This embodiment provides a safe battery. Except that lithium hydroxide is also added as a lithium supplement agent in the PET film, and based on the total mass of the PET film, the content of the lithium supplement agent is 0.5%, the remaining steps and conditions are the same as those in Embodiment 2, so they will not be elaborated here.

[0088] Embodiment 7

[0089] This embodiment provides a safe battery. Except that a nickel-chromium alloy layer with a thickness of 50 nm is deposited on the surface of the dried functional layer by magnetron sputtering as a primer layer, and a texture structure is formed after rolling at 100 kPa, and based on the single-sided area of the primer layer, the area ratio of the texture structure is 50%, the remaining steps and conditions are the same as those in Embodiment 2, so they will not be elaborated here.

[0090] Embodiment 8

[0091] This embodiment provides a safe battery. Except that the area ratio of the texture structure is changed to 20%, the remaining steps and conditions are the same as those in Embodiment 7, so they will not be elaborated here.

[0092] Embodiment 9

[0093] This embodiment provides a safe battery. Except that the area ratio of the texture structure is changed to 80%, the remaining steps and conditions are the same as those in Embodiment 7, so they will not be elaborated here.

[0094] Embodiment 10

[0095] This embodiment provides a safe battery. Except that the mixing mass ratio of acrylate and vinyl ethylene carbonate is changed to 1:0.2, the remaining steps and conditions are the same as those in Embodiment 1, so they will not be elaborated here.

[0096] Embodiment 11

[0097] This embodiment provides a safe battery. Except that the mixing mass ratio of acrylate and vinyl ethylene carbonate is changed to 1:0.5, the remaining steps and conditions are the same as those in Embodiment 1, so they will not be elaborated here.

[0098] Example 12

[0099] This example provides a safe battery. Except that the content of titanium dioxide particles is changed to 6%, the remaining steps and conditions are the same as those in Example 2, so they will not be elaborated here.

[0100] Example 13

[0101] This example provides a safe battery. Except that the area ratio of the texture structure is changed to 10%, the remaining steps and conditions are the same as those in Example 7, so they will not be elaborated here.

[0102] Example 14

[0103] This example provides a safe battery. Except that the area ratio of the texture structure is changed to 90%, the remaining steps and conditions are the same as those in Example 7, so they will not be elaborated here.

[0104] Example 15

[0105] This example provides a safe battery. Except that the porosity of the functional layer is changed to 20%, the remaining steps and conditions are the same as those in Example 1, so they will not be elaborated here.

[0106] Example 16

[0107] This example provides a safe battery. Except that the porosity of the functional layer is changed to 40%, the remaining steps and conditions are the same as those in Example 1, so they will not be elaborated here.

[0108] Example 17

[0109] This example provides a safe battery. Except that the porosity of the functional layer is changed to 50%, the remaining steps and conditions are the same as those in Example 1, so they will not be elaborated here.

[0110] Comparative Example 1

[0111] This comparative example provides a battery. Except that instead of coating the functional layer on both surfaces of the PET film, a metal layer is directly deposited on both surfaces of the PET film, the remaining steps and conditions are the same as those in Example 1, so they will not be elaborated here.

[0112] Comparative Example 2

[0113] This comparative example provides a battery. Except that the mixing mass ratio of acrylate and vinyl ethylene carbonate is changed to 1:0.1, the remaining steps and conditions are the same as those in Example 1, so they will not be elaborated here.

[0114] Comparative Example 3

[0115] This comparative example provides a battery. Except that the mixing mass ratio of acrylate and vinyl ethylene carbonate is changed to 1:0.6, the remaining steps and conditions are the same as those in Example 1, so they will not be elaborated here.

[0116] Performance Test

[0117] (A) Adhesion strength: Using a peel force tester, take a sample with a size of 120 mm × 50 mm, stick it on a steel plate with tape pre - pasted, use a 2 kg pressure roller to roll back and forth 2 times to ensure the surface of the sample is flat. Then, paste a tape with a size of 22 cm × 12.7 mm on the surface of the sample, use a 2 kg pressure roller to roll back and forth 2 times, and then place it on the peel force tester. After fixing, peel them at an angle of 180° and a speed of 100 mm / min to test the peel force, and thus obtain the bonding strength between the metal layer and the base film layer before coating the active material and after formation treatment.

[0118] (B) Tensile strength: Refer to the standard of GB / T 1040.3 - 2006 to test the tensile strength of the current collector.

[0119] (C) Penetration test: When the battery is in a 75% SOC state, use a high - strength stainless steel with a diameter of 3 mm to penetrate it at a penetration speed of 20 mm / s and pierce the whole battery; monitor the highest temperature during the penetration process.

[0120] (D) Cycle performance: Place the battery in a cycle performance test device, and conduct charge - discharge cycle experiments in a charge - discharge voltage range of 3.0 V - 3.8 V at a rate of 0.2C, and record the battery capacity retention rate after 100 charge - discharge cycles.

[0121] The relevant test results are shown in Table 1 below.

[0122] Table 1

[0123]

[0124]

[0125] In the above table, adhesion strength A refers to the adhesion strength between the metal layer and the base film layer before coating the active material, and adhesion strength B refers to the adhesion strength between the metal layer and the base film layer after formation treatment.

[0126] In the above-mentioned acupuncture experiment, the metal layer of the traditional functional current collector (such as Comparative Example 1) generates cracks under mesoscopic plastic deformation, which can directly cut off the electronic path to prevent internal short circuits, or utilize the thermal shrinkage of the material and the shedding of the metal layer to timely cut off the Joule heat generated by the internal short circuit caused by nail piercing. Since the metal layer and the base film layer of the safety current collector provided by the present invention are delaminated and the thickness of the metal layer is ultra-thin, during the acupuncture experiment, the metal layer rapidly extends outward at the acupuncture point to generate many micro-cracks or even large cracks, thereby cutting off the current path and achieving an open circuit instantaneously during acupuncture, further improving the safety performance.

[0127] In addition, the acupuncture experiment of the traditional functional current collector shows that although it can reduce the risk of fire and explosion, the peak temperature is still relatively high (above 850 °C) due to its weak heat dissipation ability. Since the safety current collector provided by the present invention shortens the open circuit formation time, it can effectively reduce the energy rapidly released by the internal short circuit point in a short time, and thus effectively reduce the peak temperature, not only further improving the safety performance of the battery, but also reducing the thermal shrinkage rate and mechanical property requirements of the separator. Due to the low peak temperature, the thermal shrinkage rate of the separator will decrease, and since the safety performance is high, the requirement for the puncture resistance strength of the separator will also decrease, and the porosity of the separator can be higher, and a porous organic film without a ceramic layer can be used as the battery separator in the present invention.

[0128] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by any person skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A safe battery, characterized in that: The safety type battery adopts a safety type current collector, and the safety type current collector comprises a base film layer and a metal layer arranged on at least one side surface of the base film layer; Before the active material is coated on the safety current collector, the bonding strength between the base film layer and the metal layer is ≥300N / m; after the safety current collector is assembled into a battery cell and subjected to a chemical formation treatment, the bonding strength between the base film layer and the metal layer is 0; Wherein, the single layer thickness of the metal layer is ≤2 μm.

2. The safety battery according to claim 1, characterized in that: A functional layer is also provided on at least one side surface of the base film layer; Wherein, the material of the functional layer includes acrylate and vinyl carbonate; And / or, the mass ratio of the acrylic ester to vinyl ethylene carbonate is 1:(0.2-0.5).

3. The safety battery according to claim 2, characterized in that: The interior of the base film layer contains inorganic particles; Wherein, the Mohs hardness of the inorganic particles is ≥4; And / or, based on the total mass of the base film layer as a calculation basis, the content of the inorganic particles is 0.5%-5%.

4. The safety battery according to claim 3, characterized in that: The material of the inorganic particles includes any one of silicon dioxide, titanium dioxide, aluminum oxide, magnesium oxide or iron phosphate, or a combination of at least two thereof; And / or, the base film layer further contains a lithium supplement, and the lithium supplement includes any one of lithium hydroxide, lithium-rich lithium nickel oxide, lithium-rich lithium iron oxide, lithium-rich lithium oxalate, lithium-rich lithium manganese oxide or lithium-rich lithium cobalt oxide, or a combination of at least two thereof.

5. The safety battery according to claim 2, characterized in that: The material of the base film layer includes any one of polypropylene, polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyimide, polypropylene, polyvinyl chloride, polyvinylidene fluoride, polytetrafluoroethylene, polyphenylene sulfide, polyphenylene oxide, polystyrene or polyamide, or a combination of at least two thereof; And / or, the thickness of the base film layer is 1-10 μm; And / or, the material of the metal layer includes any one of titanium, silver, aluminum, aluminum alloy, nickel, nickel alloy, copper or copper alloy; And / or, the single layer thickness of the metal layer is 0.8-1.2 μm.

6. The safety battery according to claim 2, characterized in that: A primer layer is provided between the base film layer and the metal layer; The surface of the primer layer close to the metal layer has a texture structure, and after the metal layer is layered, the primer layer is attached to the surface of the metal layer; And / or, taking the single-side area of ​​the base layer as a calculation basis, the area proportion of the texture structure is 20%-80%.

7. The safety battery according to claim 6, characterized in that: The material of the base layer includes any one of nickel-chromium alloy, aluminum oxide, silicon oxide, titanium oxide, elemental nickel, elemental chromium, elemental titanium, nickel-chromium-copper alloy or silicon-aluminum alloy.

8. The safety battery according to claim 2, characterized in that: The porosity of the functional layer is ≤40%; And / or, the single layer thickness of the functional layer is 20-2000 nm.

9. The safety battery according to claim 2, characterized in that: At least one side surface of the safety current collector is also provided with a protective layer; The material of the protective layer includes any one of nickel, nickel oxide, nickel-based alloy, chromium, chromium oxide, copper oxide, copper-based alloy, aluminum oxide, silicon oxide, cobalt oxide, graphite, carbon black, copper chromate, copper chromite, carbon nano-quantum dots, carbon nanotubes, carbon nanofibers, graphene or carbon fluoride; And / or, the single layer thickness of the protective layer is 10-100 nm.

10. An electrical device, characterized in that: The electrical device comprises the safe battery as claimed in any one of claims 1 to 9.

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