Current collector, battery monomer and power device

Abstract

The utility model discloses a current collector, a battery monomer and a power device, the current collector comprises a foil material, the foil material is provided with a through hole, and the through hole is filled with a thermosensitive insulating material; the surfaces of the two sides, in the thickness direction, of the foil are coated with the first coating, and the first coating is configured to generate inert gas under the preset condition; and the second coating is coated on the surface of one layer, far away from the foil, of the first coating. According to the current collector disclosed by the utility model, the first coating capable of generating inert gas at high temperature is coated on the current collector, so that the pressure in the battery cell is increased, the anti-explosion valve can be opened in advance for heat dissipation, the violent degree of thermal runaway in the battery cell and the explosion risk are reduced, and the safety coefficient in the battery cell is improved; and the thermosensitive insulating material melts under the influence of temperature rise, expands in volume, flows out of the through holes and covers the surface of the foil, so that the surface of the foil is insulated, and the condition of short circuit is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of battery manufacturing, in particular to a current collector, a battery monomer and a power device. Background Art

[0002] It is pointed out in the relevant technology that the electrical properties and safety performance of lithium-ion batteries are greatly affected by the composition of the electrolyte, and LiPF6 is the most widely used lithium salt in lithium-ion batteries and an important component of the electrolyte. However, LiPF6 is easy to decompose at high temperatures (above 60°C) to produce PF5, and PF5 is a strong acid that will corrode the current collector, especially in a high temperature environment. At the same time, LiPF6 is also easy to hydrolyze, thereby producing HF, which will also increase the risk of corrosion of the current collector. As time goes by, the current collector is corroded more and more seriously, which will increase the interface resistance between the active material and the current collector, resulting in a cycle jump; at the same time, because the current collector has a strong electron transmission ability, when a short circuit occurs inside the battery cell, the short-circuit internal resistance at the interface between the current collector and the active material is extremely small, resulting in a large short-circuit current, which causes the battery cell to rapidly run out of control due to its local temperature rising sharply. In this regard, it is necessary to develop a corrosion-resistant, thermal runaway short-circuit resistance, and highly safe current collector to improve battery safety and long-term cycle stability.

[0003] At present, the main improvement methods for the current collector corrosion problem caused by electrolyte include the following: ① Use LiFSI, a lithium salt with high thermal stability (decomposition temperature greater than 200°C) and non-hydrolyzable, to reduce the proportion of LiPF6; ② Control the impurity elements present in the electrolyte preparation process, especially halogen elements, and control the content of water and acid ions; ③ Coat a layer of mixed coating of carbon materials such as graphene / carbon nanotubes on the surface of the current collector.

[0004] However, there are few current collectors that can suppress excessive short-circuit current and reduce the severity of thermal runaway of battery cells. At the same time, the heat dissipation time before thermal runaway of battery cells is also an important factor affecting heat diffusion.

[0005] Among them, solution ① will increase the cost of electrolyte; the content of impurity elements in solution ② has been controlled with the improvement of lithium salt preparation technology, and the content of halogen elements is basically kept within 1ppm, with very limited room for improvement, and the water content is also strictly controlled. In addition, the water inside the battery may be generated by side reactions caused by the electrolyte at a certain voltage (such as SEI film formation and high voltage decomposition); at the same time, the current commercial current collector is not sensitive enough to thermal runaway caused by short circuits in the battery cell, and there is a lack of a high-safety current collector that can effectively inhibit the spread of the short circuit area. Utility Model Content

[0006] The utility model aims to solve at least one of the technical problems existing in the prior art. To this end, the utility model proposes a current collector, which can avoid the occurrence of short circuits and reduce the severity of thermal runaway in the battery cell.

[0007] The utility model also provides a battery monomer having the current collector.

[0008] The utility model also provides a battery pack having the battery monomer.

[0009] According to the first aspect of the utility model, the current collector includes: a foil material, on which a through hole is formed, and the through hole is filled with a thermosensitive insulating material; a first coating layer, which is applied to the two side surfaces of the foil material in the thickness direction, and the first coating layer is configured to generate an inert gas under preset conditions; and a second coating layer, which is applied to a surface of the first coating layer away from the foil material.

[0010] According to the current collector of the utility model, by coating the first coating which can generate inert gas at high temperature on the current collector, the pressure inside the battery cell is increased, so that the explosion-proof valve can be opened in advance to dissipate heat, thereby reducing the severity of thermal runaway and the risk of explosion in the battery cell, and improving the safety factor inside the battery cell. In addition, by filling the through hole with heat-sensitive insulating material, the surface density of the current collector is reduced, the mass energy density of the battery cell is improved, and the production cost is reduced. The current collector has the dual effects of anti-corrosion and improving the conductivity of the current collector, thereby improving the electrical performance of the battery cell.

[0011] In some embodiments, the first coating is a coating comprising an inorganic salt of bicarbonate.

[0012] In some embodiments, the first coating has a thickness in the range of 0.1 μm-10 μm.

[0013] In some embodiments, the through holes include a plurality of through holes, the plurality of through holes are arranged at intervals, and the number of the through holes is 3000-4000 / cm 2 within the range.

[0014] In some embodiments, the diameter of each through hole is in the range of 5-20 μm.

[0015] In some embodiments, the carbon content of the second coating layer is not higher than 10%, and / or the thickness of the second coating layer is not less than 1 μm.

[0016] In some embodiments, the melting point of the heat-sensitive insulating material is greater than 80°C.

[0017] In some embodiments, the foil is aluminum foil or copper foil, and the thickness of the foil is not less than 4 μm.

[0018] A battery cell according to a second aspect of the present invention comprises a current collector according to the first aspect of the present invention.

[0019] According to the battery cell of the utility model, by setting the current collector of the first aspect mentioned above, the overall performance of the battery cell is improved, the occurrence of battery cell short circuit is avoided, the diffusion of the short circuit area is reduced, the severity of thermal runaway in the battery cell is reduced, the safety factor of the battery cell is improved, and the production cost of the battery cell is reduced.

[0020] The power device according to the third aspect of the utility model comprises a plurality of battery cells according to the second aspect of the utility model.

[0021] According to the power device of the utility model, by providing the battery monomer of the second aspect, the overall performance of the power device is improved, the safety factor of the power device is improved, and the production cost of the power device is reduced.

[0022] Additional aspects and advantages of the present invention will be given in part in the following description, and in part will become apparent from the following description, or will be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic diagram of a current collector according to an embodiment of the utility model;

[0024] Figure 2 yes Figure 1 Schematic cross-sectional view of the current collector shown in FIG.

[0025] Reference numerals:

[0026] 100. Current collector;

[0027] 1. Foil; 11. Through hole;

[0028] 2. First coating; 3. Second coating;

[0029] 4. Thermosensitive insulating materials. DETAILED DESCRIPTION

[0030] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0031] Reference below Figure 1 and Figure 2 The current collector 100 according to the first embodiment of the present invention is described.

[0032] like Figure 1 As shown, the current collector 100 according to the first embodiment of the utility model includes: a foil 1, a first coating 2 and a second coating 3.

[0033] Specifically, a through hole 11 is formed on the foil 1, and the through hole 11 is filled with a thermosensitive insulating material 4, a first coating 2 is coated on both sides of the foil 1 in the thickness direction, the first coating 2 is configured to generate an inert gas under a preset condition, and a second coating 3 is coated on a surface of the first coating 2 away from the foil 1. Therefore, the current collector 100 has a simple structure and a high safety factor.

[0034] When an internal short circuit occurs in a certain area of ​​the electrode in the battery cell, the temperature of the area will rise rapidly. At this time, the thermosensitive insulating material 4 in the through hole 11 is affected by the temperature rise and melts, expands in volume, flows out of the through hole 11, and covers the surface of the foil 1, so that the surface of the foil 1 is insulated, avoiding the occurrence of a short circuit; and the thermal decomposition material in the first coating 2 will produce CO2 or other inert gases when heated, which increases the internal pressure of the battery cell, and the explosion-proof valve opens in advance to achieve the effect of early heat dissipation.

[0035] According to the current collector 100 of the embodiment of the utility model, by coating the first coating 2 that can generate inert gas at high temperature on the current collector 100, the pressure inside the battery cell is increased, so that the explosion-proof valve can be opened in advance to dissipate heat, thereby reducing the severity of thermal runaway and the risk of explosion in the battery cell, and improving the safety factor inside the battery cell. In addition, filling the through hole 11 with a thermosensitive insulating material 4 reduces the surface density of the current collector 100, improves the mass energy density of the battery cell, and reduces the production cost. The current collector 100 also has the dual effects of anti-corrosion and improving the conductivity of the current collector 100, thereby improving the electrical performance of the battery cell.

[0036] Optionally, the first coating 2 is a coating of an inorganic salt containing bicarbonate. Specifically, the first coating 2 can be a sodium bicarbonate coating, the first coating 2 can also be a potassium bicarbonate coating, the first coating 2 can also be a calcium bicarbonate, and so on. When the temperature inside the battery cell rises due to a large area short circuit, the thermal decomposition material in the first coating 2 will be heated to produce CO2 or other inert gases, which will increase the internal pressure of the battery cell, and the explosion-proof valve will open in advance, achieving the effect of early heat dissipation.

[0037] In some embodiments of the present invention, the thickness of the first coating 2 is in the range of 0.1 μm-10 μm. For example, the thickness of the first coating 2 can be 0.1 μm, 0.2 μm, 0.4 μm, 0.6 μm, 0.8 μm, 1.0 μm, 1.5 μm, 2.0 μm, 2.5 μm, 3.0 μm, 3.5 μm, 4.0 μm, 4.5 μm, 5.0 μm, 5.5 μm, 6.0 μm, 6.5 μm, 7.0 μm, 7.5 μm, 8.0 μm, 8.5 μm, 9.0 μm, 9.5 μm, 10.0 μm, etc.

[0038] In some embodiments of the present invention, Figure 1 As shown, the through holes 11 include a plurality of through holes 11, and the plurality of through holes 11 are arranged at intervals, and the number of through holes 11 is 3000-4000 / cm 2 In the range of , the tensile strength per unit area of ​​the foil material 1 is in the range of 100Mpa-300Mpa, and the elongation of the foil material 1 is in the range of 1.5-4.5. Thus, the strength of the current collector 100 is ensured while the number of through holes 11 is ensured, and the overall structural design is ingenious.

[0039] For example, the number of through holes 11 may be 3000 / cm 2 , 3100 pieces / cm 2 , 3200 pieces / cm 2 、3300pcs / cm 2 、3400pcs / cm 2 , 3500 pieces / cm 2 , 3600 pieces / cm 2 、3700pcs / cm 2 、3800pcs / cm 2 、3900pcs / cm 2 , 4000 pieces / cm 2 and so on; the tensile strength per unit area of ​​the foil 1 can be 100Mpa, 110Mpa, 120Mpa, 130Mpa, 140Mpa, 150Mpa, 160Mpa, 170Mpa, 180Mpa, 190Mpa, 200Mpa, 210Mpa, 220Mpa, 230Mpa, 240Mpa, 250Mpa, 260Mpa, 270Mpa, 280Mpa, 290Mpa, 300Mpa and the like; the elongation of the foil 1 can be 1.5, 2, 2.5, 3, 3.5, 4, 4.5 and the like.

[0040] In some embodiments of the present invention, the aperture of each through hole 11 is in the range of 5-20 μm. For example, the aperture of the through hole 11 can be 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, etc.

[0041] In some embodiments of the utility model, the carbon content of the second coating 3 is not higher than 10%, and / or the thickness of the second coating 3 is not lower than 1 μm. Specifically, a single or mixed material such as activated carbon / carbon black / graphene / carbon nanotube is dispersed in an oily dispersant and a binder, and the carbon material content is not higher than 10%. Then, the slurry is applied to the surface of the graphene / copper foil by a coating machine, and the coating thickness is adjusted by the thickness of the scraper. After one side is dried, the other side is coated.

[0042] Furthermore, the carbon material of the second coating layer 3 can be conductive carbon black, graphene, carbon nanotubes or other carbon materials with good conductivity, and the thickness of the carbon layer is not less than 1 μm. The solvent of the mixed slurry used for coating can be water-based or oil-based such as NMP, and the binder can be one or more of PVDF, CMC, and SBR.

[0043] In some embodiments of the present invention, the melting point of the thermosensitive insulating material 4 is greater than 80°C. When an internal short circuit occurs in a certain area of ​​the electrode in the battery cell, the temperature of the area will rise rapidly. At this time, the thermosensitive insulating material 4 in the through hole 11 is affected by the temperature rise and melts, expands in volume, flows out of the through hole 11, and covers the surface of the foil 1, so that the surface of the foil 1 is insulated. For example, the melting point of the thermosensitive insulating material 4 can be 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, etc.

[0044] Specifically, the thermosensitive insulating material 4 has insulating properties, poor thermal conductivity, good chemical stability, and is insoluble in water and organic solvents, and can be PET, PTFE or other materials. The thermosensitive insulating material 4 can be injected into the through hole 11 by coating, spraying, sputtering, etc.

[0045] Furthermore, the thermosensitive insulating material 4 is heated to a temperature above the melting point in the coating device, and then coated on the surface of the perforated foil 1 and filled in the through hole 11. When the temperature drops below its melting point, the insulating material solidifies and is built into the through hole 11. Then, by laser cleaning or other cleaning methods, by adjusting the power of the cleaning equipment, the excess thermosensitive insulating material 4 on the surface of other areas outside the through hole 11 is cleaned, while ensuring that the thermosensitive insulating material 4 in the through hole 11 is not seriously damaged, and then the current collector 100 is placed in a high-temperature hydrogen atmosphere above 500°C to eliminate the trace oxide layer generated by laser cleaning. Then, the slurry mixed with the thermal decomposition gas-generating material is coated on the surface of the foil 1 by coating, spraying, sputtering, etc. and dried, and finally the slurry mixed with various carbon materials is coated on the surface of the foil 1 and dried.

[0046] In some embodiments of the present invention, the foil 1 is aluminum foil or copper foil, and the thickness of the foil 1 is not less than 4 μm, preferably in the range of 4 μm-15 μm. Further, the shape, diameter and number of the through holes 11 are not limited, and the foil 1 can be aluminum foil, copper foil or other materials with good conductivity.

[0047] The battery cell according to the embodiment of the second aspect of the utility model includes the current collector 1000 according to the embodiment of the first aspect of the utility model.

[0048] According to the battery cell of the embodiment of the utility model, by setting the current collector 100 of the first aspect embodiment, the overall performance of the battery cell is improved, the occurrence of battery cell short circuit is avoided, the diffusion of the short circuit area is reduced, the severity of thermal runaway in the battery cell is reduced, the safety factor of the battery cell is improved, and the production cost of the battery cell is reduced.

[0049] The power device according to the embodiment of the third aspect of the utility model comprises a plurality of battery cells according to the embodiment of the second aspect of the utility model.

[0050] According to the power device of the embodiment of the utility model, by setting the battery monomer of the above-mentioned second aspect embodiment, the overall performance of the power device is improved, the safety factor of the power device is improved, and the production cost of the power device is reduced.

[0051] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0052] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present utility model, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0053] In the present invention, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fix" and the like 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, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0054] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0055] Although the embodiments of the present invention have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A current collector, characterized in that: include: A foil material, wherein a through hole is formed on the foil material, and the through hole is filled with a heat-sensitive insulating material; A first coating layer, the first coating layer is applied to both side surfaces of the foil material in a thickness direction, and the first coating layer is configured to generate an inert gas under a preset condition; The second coating layer is coated on a surface of the first coating layer which is away from the foil material.

2. The current collector according to claim 1, characterized in that: The first coating is a coating comprising an inorganic salt of bicarbonate.

3. The current collector according to claim 2, characterized in that: The thickness of the first coating layer is in the range of 0.1 μm-10 μm.

4. The current collector according to claim 3, characterized in that: The through holes include a plurality of through holes, the plurality of through holes are arranged at intervals, and the number of the through holes is 3000-4000 / cm 2 within the range.

5. The current collector according to claim 4, characterized in that: The diameter of each through hole is in the range of 5-20 μm.

6. The current collector according to any one of claims 1 to 5, characterized in that: The carbon content of the second coating layer is not higher than 10%, and / or the thickness of the second coating layer is not lower than 1 μm.

7. The current collector according to any one of claims 1 to 5, characterized in that: The melting point of the heat-sensitive insulating material is greater than 80°C.

8. The current collector according to any one of claims 1 to 5, characterized in that: The foil material is aluminum foil or copper foil, and the thickness of the foil material is not less than 4 μm.

9. A battery cell, characterized in that: The present invention comprises the current collector according to any one of claims 1 to 8.

10. A power device, characterized in that: The invention comprises a plurality of battery cells as claimed in claim 9.

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