Secondary battery, electric device, separator and method for manufacturing same

Abstract

The invention provides a secondary battery, an electric device, an isolating membrane and a preparation method thereof, the secondary battery comprises a composite matrix layer and a latticed bonding layer, the composite matrix layer comprises at least two layers of base membranes and at least one solid electrolyte layer arranged between every two layers of base membranes, and the latticed bonding layer is arranged on at least one side of the composite matrix layer. The secondary battery in the present application can give consideration to both high safety performance and low internal resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a separator film, a preparation method thereof, a secondary battery and a power utilization device. BACKGROUND

[0002] In recent years, with the increasingly wide application of secondary batteries, secondary batteries are widely used in energy storage power supply systems such as hydraulic, thermal, wind and solar power stations, and in many fields such as electric tools, electric bicycles, electric motorcycles, electric vehicles, aerospace, etc. Due to the great development of secondary batteries, higher requirements are put forward for their electrical performance and safety performance.

[0003] As an important component of secondary batteries, the performance of the separator film affects the performance of the secondary battery to some extent. At present, the separator film is usually composed of a base film and a functional coating layer, but the safety performance and electrical performance cannot be considered when using the above separator film. SUMMARY

[0004] The present application is made in view of the above-mentioned problems, and aims to provide a secondary battery, a power utilization device, a separator film and a preparation method thereof. The secondary battery in the present application can consider both high safety performance and low internal resistance.

[0005] To achieve the above-mentioned purpose, the present application provides a secondary battery in the first aspect, comprising a positive electrode sheet, a negative electrode sheet and a separator film arranged between the positive electrode sheet and the negative electrode sheet; the separator film comprises: a composite substrate layer comprising at least two base films and at least a solid electrolyte layer arranged between each two base films; a grid-shaped adhesive layer arranged on at least one side of the composite substrate layer.

[0006] In the present application, since the separator film comprises at least two base films, the at least two base films simultaneously close the pores at high temperature, which can sufficiently block the transmission path of active ions, thereby improving the safety performance of the battery; in addition, the solid electrolyte layer arranged in the separator can improve the transmission efficiency of active ions, thereby being conducive to reducing the internal resistance of the secondary battery. On this basis, the adhesive layer is arranged in a grid shape, which can reduce the contact area between the adhesive layer and the electrode sheet, i.e. reduce the influence of the adhesive layer on the internal resistance of the secondary battery, which can reduce the internal resistance of the secondary battery on the basis of realizing the adhesion between the separator film and the electrode sheet. Based on the above analysis, the separator film of the present application can consider both high safety performance and low internal resistance.

[0007] In some embodiments, the isolation film further comprises: a heat-resistant layer; the heat-resistant layer is arranged at least between the composite matrix layer and the grid-shaped adhesive layer. The heat-resistant layer can protect the composite matrix layer, reduce the risk of performance degradation of the composite matrix layer due to excessive temperature, and further improve the safety performance of the isolation film.

[0008] In some embodiments, the composite matrix layer comprises two base films and the solid-state electrolyte layer arranged between the two base films. By arranging the solid-state electrolyte layer between the base films, the internal resistance of the battery can be further reduced.

[0009] In some embodiments, the porosity of the base film is 45% to 55%. Thus, the air permeability of the isolation film is improved, and the internal resistance of the battery is further reduced.

[0010] In some embodiments, the material of the at least two base films is the same or different. The use of the same material for the at least two base films simplifies the structure of the isolation film. The use of different materials for the at least two base films allows for differentiated settings of the isolation film, which can more fully block the transmission path of active ions and thus improve the safety performance of the battery.

[0011] In some embodiments, the base film comprises one or more of a polyethylene-based film, a polypropylene-based film, a polyethylene-polypropylene composite base film, a polyethylene non-woven base film, a polypropylene non-woven base film, a polypropylene-polyethylene-polypropylene composite base film, a polyimide base film, a polyimide non-woven base film, a polytetrafluoroethylene base film, a polytetrafluoroethylene non-woven base film, a polyvinyl chloride base film, or a polyvinyl chloride non-woven base film. The above-mentioned base films have the advantages of low cost, stable chemical properties, and excellent mechanical properties, which can improve the chemical stability and mechanical properties of the isolation film.

[0012] In some embodiments, the thickness of the base film is 5 μm to 15 μm. Thus, the isolation film has appropriate mechanical stability and chemical stability, which can balance the high safety performance and low internal resistance of the battery.

[0013] In some embodiments, the grid width of the grid-shaped adhesive layer is 200 μm to 500 μm. Thus, the adhesion between the isolation film and the pole piece can be achieved while reducing the internal resistance of the secondary battery.

[0014] In some embodiments, the spacing between two adjacent grids of the grid-shaped adhesive layer is 1000 μm to 5000 μm. Thus, the internal resistance of the secondary battery can be reduced.

[0015] In some embodiments, the thickness of the grid-shaped adhesive layer is 0.4 μm to 1 μm. Thus, the internal resistance of the battery can be further reduced.

[0016] In some embodiments, the solid-state electrolyte layer comprises a first electrolyte material, a first ceramic material and a first binder; and the mass ratio of the first electrolyte material, the first ceramic material and the first binder is (4-9):(0-4):(1-2). On the one hand, this is conducive to reducing the ion impedance of the isolation film, thereby reducing the internal resistance of the battery; on the other hand, by introducing the first ceramic material into the solid-state electrolyte layer, the heat resistance of the isolation film can be improved, which is conducive to further improving the safety performance.

[0017] In some embodiments, the first electrolyte material comprises one or more of LGLZO, LiGe2(PO4)3, LZTO, LLTO, LiT2(PO4)3, LLZO, LATP, LAGP, and LLAZO. The above-mentioned first electrolyte material has the advantages of high ion migration coefficient, and is used as the main material of the solid-state electrolyte layer, which can further reduce the internal resistance of the battery.

[0018] In some embodiments, the thickness of the solid-state electrolyte layer is 1-5 μm. Thus, it is conducive to further reducing the internal resistance of the battery.

[0019] In some embodiments, the heat-resistant layer comprises a second ceramic material, a second electrolyte material and a second binder; and the mass ratio of the second ceramic material, the second electrolyte material and the second binder is (4-9):(0-4):(1-2). On the one hand, this is conducive to improving the safety performance of the battery; on the other hand, by mixing the second solid-state electrolyte material in the heat-resistant layer, the heat resistance of the isolation film can be improved, and the influence of the heat-resistant layer on the internal resistance of the battery can be reduced, i.e. the internal resistance of the battery is further reduced.

[0020] In some embodiments, the second ceramic material comprises one or more of boehmite, aluminum oxide, magnesium hydroxide, magnesium oxide, barium titanate, zinc oxide or barium sulfate. The above-mentioned second ceramic material has the advantages of good flame retardation effect, good chemical stability and good thermal stability, and is used as the main material of the heat-resistant layer, which is conducive to further improving the safety performance of the battery.

[0021] In some embodiments, the thickness of the heat-resistant layer is 0.5-2 μm. Thus, the safety performance and low internal resistance of the battery can be taken into account.

[0022] The second aspect of the present application provides a power utilization device comprising the secondary battery of the first aspect.

[0023] The third aspect of the present application provides an isolation film, comprising: a composite base layer comprising at least two base films and at least a solid-state electrolyte layer arranged between each two base films; and a grid-shaped bonding layer arranged on at least one side of the composite base layer.

[0024] In the present application, since the isolation film comprises at least two base films, the safety performance of the battery can be improved by blocking the transmission path of active ions when the at least two base films are closed at the same time in a high temperature environment. In addition, the transmission efficiency of active ions can be improved by arranging the solid electrolyte layer in the isolation film, thereby being conducive to reducing the internal resistance of the secondary battery. On this basis, the adhesion layer is arranged in a grid shape, which can reduce the contact area between the adhesion layer and the pole piece, i.e. reduce the influence of the adhesion layer on the internal resistance of the secondary battery, and can reduce the internal resistance of the secondary battery on the basis of realizing the adhesion between the isolation film and the pole piece. Based on the above analysis, the isolation film of the present application can balance high safety performance and low internal resistance.

[0025] In some embodiments, the isolation film further comprises: a heat-resistant layer; the heat-resistant layer is arranged at least between the composite matrix layer and the grid-shaped adhesion layer. The heat-resistant layer can protect the composite matrix layer, reduce the probability of performance degradation of the composite matrix layer due to excessive temperature, and be conducive to further improving the safety performance of the isolation film.

[0026] In some embodiments, the porosity of the base film is 45% to 55%. Thus, it is conducive to improving the air permeability of the isolation film and further reducing the internal resistance of the battery.

[0027] In some embodiments, the thickness of the base film is 5 μm to 15 μm. Thus, the isolation film has appropriate mechanical stability and chemical stability, which is conducive to balancing the high safety performance and low internal resistance of the battery.

[0028] In some embodiments, the grid width of the grid-shaped adhesion layer is 200 μm to 500 μm. Thus, the internal resistance of the secondary battery can be reduced on the basis of realizing the adhesion between the isolation film and the pole piece.

[0029] In some embodiments, the spacing between two adjacent grids of the grid-shaped adhesion layer is 1000 μm to 5000 μm. Thus, it is conducive to reducing the internal resistance of the secondary battery.

[0030] In some embodiments, the thickness of the grid-shaped adhesion layer is 0.4 μm to 1 μm. Thus, it is more conducive to reducing the internal resistance of the battery.

[0031] In some embodiments, the solid-state electrolyte layer comprises a first electrolyte material, a first ceramic material and a first binder; the mass ratio of the first electrolyte material, the first ceramic material and the first binder is (4-9):(0-4):(1-2). In this way, on the one hand, it is conducive to reducing the ion impedance of the separator film, thereby reducing the internal resistance of the battery, and on the other hand, by introducing the first ceramic material in the solid-state electrolyte layer, the heat resistance of the separator film can be improved, which is conducive to further improving the safety performance.

[0032] In some embodiments, the thickness of the solid-state electrolyte layer is 1-5 μm. In this way, it is conducive to further reducing the internal resistance of the battery.

[0033] In some embodiments, the heat-resistant layer comprises a second ceramic material, a second electrolyte material and a second binder; the mass ratio of the second ceramic material, the second electrolyte material and the second binder is (4-9):(0-4):(1-2). In this way, on the one hand, it is conducive to improving the safety performance of the battery, and on the other hand, by mixing the second solid-state electrolyte material in the heat-resistant layer, the heat resistance of the separator film can be improved, and at the same time, the influence of the heat-resistant layer on the internal resistance of the battery can be reduced, i.e. the internal resistance of the battery is further reduced.

[0034] In some embodiments, the thickness of the heat-resistant layer is 0.5-2 μm. In this way, the safety performance and low internal resistance of the battery can be taken into account.

[0035] The fourth aspect of the present application provides a preparation method of a separator film, comprising the following steps: a first preparation step, comprising forming a solid-state electrolyte layer on at least one surface of a base film, and then compounding another base film on the surface of the solid-state electrolyte layer to form a composite base layer; a second preparation step, comprising forming a grid-shaped adhesive layer on at least one surface of the composite base layer.

[0036] In the separator film formed by the present application, since the separator film comprises at least two base films, the closure of the at least two base films occurs at the same time in a high-temperature environment, which can fully block the transmission path of active ions, thereby improving the safety performance of the battery. In addition, by providing a solid-state electrolyte layer in the separator, the transmission efficiency of active ions can be improved, thereby being conducive to reducing the internal resistance of the secondary battery. On this basis, by setting the adhesive layer to be grid-shaped, the contact area between the adhesive layer and the pole piece can be reduced, i.e. the influence of the adhesive layer on the internal resistance of the secondary battery can be reduced, which can reduce the internal resistance of the secondary battery on the basis of realizing the adhesion between the separator film and the pole piece. Based on the above analysis, the separator film of the present application can take into account high safety performance and low internal resistance.

[0037] In some embodiments, in the second preparation step, the adhesive layer paste is coated by using a grid structure gravure roll to form the grid-shaped adhesive layer. In this way, the grid-shaped adhesive layer can be obtained, so as to reduce the internal resistance of the secondary battery on the basis of realizing the adhesion between the separator film and the pole piece.

[0038] In some embodiments, in the first preparation step, the first paste is coated on the surface of at least one base film by using a roll coating method to form the solid electrolyte layer. The formation of the composite base layer under the above conditions is conducive to forming a composite base layer with appropriate thickness and uniformity, so as to facilitate the high safety performance and low internal resistance of the battery.

[0039] In some embodiments, in the first preparation step, after the other base film is compounded on the surface of the solid electrolyte layer, the drying treatment is carried out at 40-90°C for 1-3 min.

[0040] In some embodiments, the first preparation step further comprises coating a second paste on at least one side of the composite base layer to form a heat-resistant layer. In this way, it is conducive to further improving the safety performance of the separator film. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 is a sectional view of a separator film according to an embodiment of the present application.

[0042] Figure 2 is a top view of a separator film according to an embodiment of the present application.

[0043] Figure 3 is a schematic view of a battery cell according to an embodiment of the present application.

[0044] Figure 4 is a schematic view of a battery cell according to an embodiment of the present application. Figure 3 is an exploded view of a battery cell according to an embodiment of the present application.

[0045] Figure 5 is a schematic view of a battery module according to an embodiment of the present application.

[0046] Figure 6 is a schematic view of a battery pack according to an embodiment of the present application.

[0047] Figure 7 is a schematic view of a battery pack according to an embodiment of the present application. Figure 6 is an exploded view of a battery pack according to an embodiment of the present application.

[0048] Figure 8 is a schematic view of an electric device using a secondary battery as a power source according to an embodiment of the present application.

[0049] BRIEF DESCRIPTION OF DRAWINGS

[0050] 1: battery pack; 2: upper case; 3: lower case; 4: battery module; 5: battery cell; 51: case; 52: electrode assembly; 53: top cap assembly; 11: composite base layer; 111: base film; 112: solid electrolyte layer; 12: heat-resistant layer; 13: grid-shaped adhesive layer. DETAILED DESCRIPTION

[0051] Hereinafter, embodiments of a secondary battery, an electric device, a separator, and a method of manufacturing the same according to the present application will be described in detail with appropriate reference to the accompanying drawings. However, there will be cases where unnecessary detailed descriptions are omitted. For example, there will be cases where detailed descriptions of matters well-known in the art, repeated descriptions of substantially identical configurations, are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present application, and are not intended to limit the subject matter recited in the claims.

[0052] The ranges disclosed herein are defined by their lower and upper limits, and are presented herein for purposes of exemplification as being inclusive of the endpoints and all the individual ranges between the endpoints. Other ranges of any one of the parameters disclosed herein are also contemplated, and any lower limit can be combined with any upper limit to define a range. For example, if a range of 60-120 and a range of 80-110 are disclosed, it is understood that a range of 60-110 and a range of 80-120 are also contemplated. Furthermore, if a minimum range value of 1 and 2 are disclosed, and if a maximum range value of 3, 4, and 5 are disclosed, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In the present application, unless otherwise stated, a numerical range "a-b" indicates a shorthand manner of describing each and every individual amount that is within the scope of the range of a to b, wherein a and b are both real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed herein, and "0-5" is merely a shorthand manner of describing each and every individual amount that is within the scope of the range of 0 to 5. In addition, when it is stated that a parameter is an integer ≥ 2, it is equivalent to disclose that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0053] If not specifically stated, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0054] If not specifically stated, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

[0055] If not otherwise specified, all steps of the present application can be carried out in sequence or randomly, preferably in sequence. For example, the method comprising steps (a) and (b) means that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, the method mentioned can further comprise step (c), which means that step (c) can be added to the method in any sequence, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0056] If not otherwise specified, the terms used in the present application have the common meanings generally understood by those skilled in the art.

[0057] If not otherwise specified, the values of the parameters mentioned in the present application can be measured by various test methods commonly used in the art, for example, can be measured according to the test methods given in the present application.

[0058] The conventional polyethylene (PE) separator and polypropylene (PP) separator are made of high molecular materials. Since the high molecular material itself has poor heat resistance and weak adhesion to the pole piece, a functional layer is usually coated on the surface of the polyethylene separator or the polypropylene separator. For example, a layer of inorganic heat-resistant layer (such as aluminum oxide coating, boehmite coating) is coated on the surface of the polyethylene separator, and then a layer of adhesion layer (such as polyvinylidene fluoride PVDF layer, polymethyl methacrylate PMMA layer) is coated on the heat-resistant layer to improve the heat resistance and adhesion of the separator.

[0059] After the functional layer is coated on the surface of the separator, although the heat resistance and adhesion of the separator can be improved, the air permeability value of the separator is reduced and the ion impedance is increased, thereby affecting the internal resistance of the battery. In addition, when the separator or the battery encounters a high temperature environment (> 130℃), the polyethylene separator or the polypropylene separator will close the pores and quickly block the internal transmission path of lithium ions. However, due to the uniformity or manufacturing factors of the separator, when the separator closes the pores, there may be local areas that do not close the pores, causing the active ion transmission path to be not fully blocked, thereby affecting the safety performance of the battery.

[0060] Based on this, the present application proposes a new secondary battery, a power consumption device, a separator and a preparation method thereof. The secondary battery in the present application can balance high safety performance and low internal resistance.

[0061] Secondary battery

[0062] The first aspect of the present application provides a secondary battery, comprising a positive electrode sheet, a negative electrode sheet, and a separator disposed between the positive electrode sheet and the negative electrode sheet; the separator comprises a composite substrate layer and a grid-shaped adhesive layer. The composite substrate layer comprises at least two base films and at least a solid electrolyte layer disposed between each two base films; the grid-shaped adhesive layer is disposed on at least one side of the composite substrate layer.

[0063] In the present application, since the separator comprises at least two base films, the at least two base films can simultaneously close pores in a high temperature environment, which can sufficiently block the transmission path of active ions, thereby improving the safety performance of the battery; in addition, by disposing a solid electrolyte layer in the separator, the transmission efficiency of active ions can be improved, thereby facilitating the reduction of the internal resistance of the secondary battery. On this basis, by setting the adhesive layer to be grid-shaped, the contact area between the adhesive layer and the electrode sheet can be reduced, i.e. the influence of the adhesive layer on the internal resistance of the secondary battery can be reduced, which can reduce the internal resistance of the secondary battery while realizing the adhesion between the separator and the electrode sheet. Based on the above analysis, the separator of the present application can balance high safety performance and low internal resistance.

[0064] In some embodiments, the separator further comprises a heat-resistant layer, which is at least disposed between the composite substrate layer and the grid-shaped adhesive layer. In some embodiments, the heat-resistant layer can also be disposed between one base film in the composite substrate layer and the solid electrolyte layer, or the heat-resistant layer can also be disposed between two base films in the composite substrate layer and the solid electrolyte layer, or when the grid-shaped adhesive layer is disposed on one side of the composite substrate layer, the heat-resistant layer can also be disposed on the side of the composite substrate layer away from the grid-shaped adhesive layer. In the present application, the heat-resistant layer can protect the composite substrate layer, reduce the probability of performance degradation of the composite substrate layer due to excessive temperature, and facilitate further improvement of the safety performance of the separator.

[0065] The following further illustrates the separator in the secondary battery of the present application in conjunction with the accompanying drawings.

[0066] Figure 1 is a sectional view of the separator in the secondary battery of an embodiment of the present application, Figure 2 is a top view of the separator in the secondary battery of an embodiment of the present application, as Figure 1 and Figure 2 shown, the separator comprises a composite substrate layer 11, a heat-resistant layer 12, and a grid-shaped adhesive layer 13, wherein the composite substrate layer 11 comprises at least two base films 111 and at least a solid electrolyte layer 112 disposed between each two base films 111; the heat-resistant layer 12 is disposed on at least one side of the composite substrate layer 12; the grid-shaped adhesive layer 13 is disposed on the side of the heat-resistant layer 12 away from the composite substrate layer 11.

[0067] The number of base films 111 included in the composite substrate layer 11 is not particularly limited. For example, the number of base films included in the composite substrate layer can be 2, 3, 4, and more.

[0068] In some embodiments, the composite substrate layer includes two base films and a solid electrolyte layer between the two base films. By arranging the solid electrolyte layer between the base films, the internal resistance of the battery is further reduced.

[0069] In some embodiments, the composite substrate layer includes two base films and a solid electrolyte layer between the two base films and on the outer surfaces of the two base films, i.e., the composite substrate layer includes three solid electrolyte layers and two base film layers, and the solid electrolyte layers and the base film layers are arranged alternately. In this way, the internal resistance of the battery is further reduced.

[0070] In some embodiments, the porosity of the base film is 45% to 55%. For example, the porosity of the base film is 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, or a value between any two of the above values. Controlling the porosity of the base film within the above range is beneficial to improve the air permeability of the separator film and further reduce the internal resistance of the battery.

[0071] In some embodiments, the materials of the at least two base films are the same or different. Using the same material for the at least two base films is beneficial to simplify the structure of the separator film. Using different materials for the at least two base films is beneficial to realize the differentiated arrangement of the separator film, and can more fully block the transmission path of active ions, thereby improving the safety performance of the battery.

[0072] In some embodiments, the base film includes one or more of a polyethylene-based film, a polypropylene-based film, a polyethylene-polypropylene composite-based film, a polyethylene non-woven fabric-based film, a polypropylene non-woven fabric-based film, a polypropylene-polyethylene-polypropylene composite-based film, a polyimide-based film, a polyimide non-woven fabric-based film, a polytetrafluoroethylene-based film, a polytetrafluoroethylene non-woven fabric-based film, a polyvinyl chloride-based film, or a polyvinyl chloride non-woven fabric-based film. The above-mentioned base films have the advantages of low cost, stable chemical properties, excellent mechanical properties, etc., which are beneficial to improve the chemical stability and mechanical properties of the separator film.

[0073] In some embodiments, the thickness of the base film is 5 μm to 15 μm. For example, the thickness of the base film is 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, or a value between any two of the above values. Controlling the thickness of the base film within the above range makes the separator film have appropriate mechanical stability and chemical stability, which is beneficial to balance the high safety performance and low internal resistance of the battery.

[0074] In some embodiments, the grid width of the grid-shaped adhesive layer is 200-500 μm. For example, the grid width of the grid-shaped adhesive layer is 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm, or a value within a range between any two of the values. The grid width of the grid-shaped adhesive layer within the above range can reduce the internal resistance of the secondary battery while maintaining the adhesion between the separation film and the electrode sheet.

[0075] In some embodiments, the distance between the two adjacent grids of the grid-shaped adhesive layer is 1000-5000 μm. For example, the distance between the two adjacent grids is 1000 μm, 2000 μm, 3000 μm, 4000 μm, 5000 μm, or a value within a range between any two of the values. The distance between the two adjacent grids of the grid-shaped adhesive layer within the above range can further reduce the internal resistance of the secondary battery while maintaining the adhesion between the separation film and the electrode sheet.

[0076] In some embodiments, the thickness of the grid-shaped adhesive layer is 0.4-1 μm. For example, the thickness of the grid-shaped adhesive layer is 0.4 μm, 0.6 μm, 0.8 μm, 1 μm, or a value within a range between any two of the values. The thickness of the grid-shaped adhesive layer within the above range can further reduce the internal resistance of the battery while maintaining the adhesion between the separation film and the electrode sheet.

[0077] In some embodiments, the solid-state electrolyte layer comprises a first electrolyte material, a first ceramic material, and a first binder; and the mass ratio of the first electrolyte material, the first ceramic material, and the first binder is (4-9):(0-4):(1-2). The mass ratio of the first electrolyte material, the first ceramic material, and the first binder within the above range can further reduce the ion impedance of the separation film, thereby further reducing the internal resistance of the battery. In addition, by introducing the first ceramic material into the solid-state electrolyte layer, the heat resistance of the separation film can be improved, thereby further improving the safety performance.

[0078] In some embodiments, the first electrolyte material comprises one or more of LGLZO (lithium garnet zirconium oxide), LiGe2(PO4)3 (lithium germanium phosphate), LZTO (lithium zirconium titanium oxide), LLTO (lithium lanthanum titanium oxide), LiT2(PO4)3 (lithium titanium phosphate), LLZO (lithium lanthanum zirconium oxide), LATP (lithium aluminum titanium phosphate), LAGP (lithium aluminum germanium phosphate), and LLAZO (lithium lanthanum aluminum zirconium oxide). The above first electrolyte material has the advantage of high ion migration coefficient and is used as the main material of the solid-state electrolyte layer, thereby further reducing the internal resistance of the battery.

[0079] In some embodiments, the first ceramic material comprises one or more of boehmite, alumina, magnesium hydroxide, magnesium oxide, barium titanate, zinc oxide, or barium sulfate.

[0080] In some embodiments, the first binder comprises one or more of polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl alcohol, polyurethane, or polystyrene acid ester.

[0081] In some embodiments, the thickness of the solid-state electrolyte layer is 1-5 μm. Illustratively, the thickness of the solid-state electrolyte layer is 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, or a value between any two of the values. The thickness of the solid-state electrolyte layer in the above range is advantageous for further reducing the internal resistance of the battery.

[0082] In some embodiments, the heat-resistant layer comprises a second ceramic material, a second electrolyte material, and a second binder; the mass ratio of the second ceramic material, the second electrolyte material, and the second binder is:

[0083] (4-9):(0-4):(1-2). The mass ratio of the second ceramic material, the second electrolyte material, and the second binder in the above range is advantageous for improving the safety performance of the battery. In addition, by mixing the second solid-state electrolyte material in the heat-resistant layer, the heat resistance of the separator film is improved, and the influence of the heat-resistant layer on the internal resistance of the battery is reduced, i.e., the internal resistance of the battery is further reduced.

[0084] In some embodiments, the second ceramic material comprises one or more of boehmite, alumina, magnesium hydroxide, magnesium oxide, barium titanate, zinc oxide, or barium sulfate. The above-mentioned second ceramic material has the advantages of good flame retardant effect, good chemical stability, and good thermal stability, etc., and is used as the main material of the heat-resistant layer, which is advantageous for further improving the safety performance of the battery.

[0085] In some embodiments, the second electrolyte material comprises one or more of LGLZO, LiGe2(PO4)3, LZTO (lithium zirconium titanate), LLTO (lithium lanthanum titanate), LiT2(PO4)3, LLZO (lithium lanthanum zirconate), LATP (lithium aluminum titanium phosphate), LAGP (lithium aluminum silicon phosphate), and LLAZO (lithium lanthanum aluminum zirconium oxide).

[0086] In some embodiments, the second binder comprises one or more of polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl alcohol, polyurethane, or polystyrene acid ester.

[0087] In some embodiments, the heat-resistant layer has a thickness of 0.5 μm to 2 μm. Illustratively, the heat-resistant layer has a thickness of 0.5 μm, 1 μm, 1.5 μm, 2 μm, or a value between any two of the values. The thickness of the heat-resistant layer in the above range can balance the safety performance and low internal resistance of the battery.

[0088] The term "secondary battery" referred to herein means a battery cell, a battery module, or a battery pack. Each is described below.

[0089] Generally, a secondary battery cell includes a positive electrode sheet, a negative electrode sheet, an electrolyte, and the separator of the first aspect. During charging and discharging of the battery, active ions are intercalated and deintercalated between the positive electrode sheet and the negative electrode sheet. The electrolyte functions to conduct ions between the positive electrode sheet and the negative electrode sheet. The separator is disposed between the positive electrode sheet and the negative electrode sheet and functions to prevent short circuiting between the positive and negative electrodes while allowing ions to pass through.

[0090] Positive electrode sheet

[0091] The positive electrode sheet includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, the positive electrode film layer including the positive electrode active material of the first aspect.

[0092] As an example, the positive electrode current collector has two surfaces opposite in the thickness direction thereof, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive electrode current collector.

[0093] In some embodiments, the positive electrode current collector can be a metal foil or a composite current collector. For example, as the metal foil, an aluminum foil can be used. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material base material (e.g., a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0094] In some embodiments, when the battery cell is a lithium ion battery, the positive electrode active material can employ a positive electrode active material for a lithium ion battery known in the art. As an example, the positive electrode active material can include at least one of a lithium-containing phosphate of an olivine structure, a lithium transition metal oxide, and a modified compound of each thereof. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery positive electrode active material can also be used. These positive electrode active materials can be used alone only or in combination of two or more. Among them, examples of the lithium transition metal oxide can include, but are not limited to, lithium cobalt oxide (e.g., LiCoO2), lithium nickel oxide (e.g., LiNiO2), lithium manganese oxide (e.g., LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (e.g., LiNi 1 / 3 Co 1 / 3Mn 1 / 3 O2(also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2(also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2(also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2(also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2(also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (e.g., LiNi 0.85 Co 0.1 Al 0.05 O2), and a modified compound thereof, etc. Examples of the lithium-containing phosphate of an olivine structure can include, but are not limited to, at least one of lithium iron phosphate (e.g., LiFePO4(also referred to as LFP)), a composite of lithium iron phosphate and carbon, lithium manganese phosphate (e.g., LiMnPO4), a composite of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite of lithium manganese iron phosphate and carbon.

[0095] The battery is accompanied by Li deintercalation and consumption during charging and discharging, and the molar content of Li is different when the battery is discharged to different states. In the enumeration of the positive electrode active material in the present application, the molar content of Li is the initial state of the material, i.e., the state before feeding, and the positive electrode active material is applied to the battery system. After charging and discharging cycles, the molar content of Li will change.

[0096] In some embodiments, when the battery cell is a sodium-ion battery, the positive active material can employ positive active materials known in the art for sodium-ion batteries. As an example, the positive active material can include at least one of sodium-containing layered oxides, polyanionic sodium-ion compounds, Prussian blue sodium-ion compounds.

[0097] As an example, the sodium-containing layered oxides can be iron-manganese-based layered oxides. The iron-manganese-based layered oxides include at least one of nickel-iron-manganese-based layered oxides and copper-iron-manganese-based layered oxides.

[0098] As an alternative technical means of the present application, the polyanionic sodium-ion compounds can be a compound having sodium ions, transition metal ions, and tetrahedral (YO4) n- anion units. The transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; Y can be at least one of P, S, and Si; and n represents the valence of (YO4) n- . The polyanionic sodium-ion compounds can also be a compound having sodium ions, transition metal ions, tetrahedral (YO4) n- anion units, and halogen anions. The transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; Y can be at least one of P, S, and Si, and n represents the valence of (YO4) n- . The halogen can be at least one of F, Cl, and Br.

[0099] The polyanionic sodium-ion compounds can also be a compound having sodium ions, tetrahedral (YO4) n- anion units, polyhedral units (ZO y ) m+ , and optional halogen anions. Y can be at least one of P, S, and Si, and n represents the valence of (YO4) n . Z represents a transition metal, which can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce, and m represents the valence of (ZO y ) m+ . The halogen can be at least one of F, Cl, and Br. The polyanionic compounds are, for example, at least one of NaFePO4, Na3V2(PO4)3, NaM’PO4F (M’ is one or more of V, Fe, Mn, and Ni), and Na3(VO y )2(PO4)2F 3-2y (0≤y≤1).

[0100] As an alternative technical means of the present application, the polyanionic sodium-ion compounds can be Nax-a A a V y-b M b (PO4) 2-2c (DO4) 2c F z-d Q d wherein A represents an alkali metal element doped to substitute Na, M represents a metal element doped to substitute V, D represents a doping element doped to substitute P, Q represents a doping element doped to substitute F, D includes at least one of Si and S, and Q includes at least one of Cl and O; 3.5≤x≤4.5, 0≤a≤0.15x, 0.8≤y≤1.1, 0≤b≤0.3y, 0≤c≤0.15, 0.8≤z≤1.1, 0≤d≤0.2z. Optionally, A includes at least one of K and Li; and M includes at least one of Fe, Cr, Al, Sc, Ga, In, Ti, Zr, Mn, Zn, Ni, Cu and Co.

[0101] As an optional technical means of the present application, the polyanionic sodium ion compound can be Na x R y (PO4)2P2O7, wherein x=3.5-4.5, y=2.75-3.25, and R includes at least one of Mg, Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Cr, Nb, Mo, In, Ga, Sn, Hf, Ta, W and Pb.

[0102] As an optional technical means of the present application, the polyanionic sodium ion compound can be Na 4+x R 3-y P 4-m O 15 / C; wherein 0

[0103] The Prussian blue compound can be a compound having sodium ions, transition metal ions and cyanide ions (CN-). The transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce. The Prussian blue compound is, for example, Na a Me b Me’ c(CN)6, wherein Me and Me’ are each independently at least one of Ni, Cu, Fe, Mn, Co, and Zn, 0 < a < 2, 0 < b < 1, and 0 < c < 1.

[0104] In the enumeration of the positive electrode active material in the present application, the molar content of O is only the theoretical state value, and the oxygen release of the crystal lattice will cause the molar content of oxygen to change, and the actual molar content of O will appear to be floating.

[0105] In some embodiments, the positive electrode film layer further optionally includes a binder. As an example, the binder can include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylic ester resin.

[0106] In some embodiments, the positive electrode film layer further optionally includes a conductive agent. As an example, the conductive agent can include at least one of super conductive carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0107] In some embodiments, the positive electrode tab can be prepared by dispersing the above-mentioned components for preparing the positive electrode tab, such as the positive electrode active material, the conductive agent, the binder, and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on a positive electrode current collector, and after processes such as drying, cold pressing, etc., the positive electrode tab can be obtained.

[0108] Negative electrode tab

[0109] The negative electrode tab includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, the negative electrode film layer including a negative electrode active material.

[0110] As an example, the negative electrode current collector has two surfaces opposite in the thickness direction thereof, and the negative electrode film layer is disposed on either one or both of the two opposite surfaces of the negative electrode current collector.

[0111] In some embodiments, the negative electrode current collector can adopt a metal foil or a composite current collector. For example, as a metal foil, a copper foil can be adopted. The composite current collector can include a high polymer material base layer and a metal layer formed on at least one surface of the high polymer material base layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a high polymer material base layer (such as a base layer of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0112] In some embodiments, the negative active material can employ a negative active material for a battery known in the art. As an example, the negative active material can include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, and lithium titanate, etc. The silicon-based material can be selected from at least one of elemental silicon, silicon oxide compound, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy. The tin-based material can be selected from at least one of elemental tin, tin oxide compound, and tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as a negative active material for a battery can also be used. These negative active materials can be used alone or in combination of two or more.

[0113] In some embodiments, the negative film layer can further optionally include a binder. The binder can be selected from at least one of styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0114] In some embodiments, the negative film layer can further optionally include a conductive agent. The conductive agent can be selected from at least one of super conductive carbon, acetylene black, carbon black, ketjen black, carbon dot, carbon nanotube, graphene, and carbon nanofiber.

[0115] In some embodiments, the negative film layer can further optionally include other auxiliary agents, such as thickening agents (e.g., sodium carboxymethyl cellulose (CMC-Na)) and the like.

[0116] In some embodiments, the negative electrode sheet can be prepared by dispersing the above-mentioned components for preparing the negative electrode sheet, such as the negative active material, the conductive agent, the binder, and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry on a negative current collector, and after drying, cold pressing, and the like, the negative electrode sheet can be obtained.

[0117] Electrolyte

[0118] The electrolyte functions to conduct ions between the positive electrode sheet and the negative electrode sheet. The present application does not have a specific limitation on the type of electrolyte, which can be selected as needed. For example, the electrolyte can be liquid, gel, or all-solid.

[0119] In some embodiments, the electrolyte employs an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0120] In some embodiments, the electrolyte salt can be selected from at least one of sodium hexafluorophosphate, sodium tetrafluoroborate, sodium perchlorate, sodium hexafluoroarsenate, sodium bisfluorosulfonimide, sodium bistrifluoromethylsulfonimide, sodium trifluoromethanesulfonate, sodium difluorophosphate, sodium difluoroboric oxalate, sodium bioric phosphate, and sodium tetrifluoroboric oxalate.

[0121] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, butyrosulfone, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0122] In some embodiments, the electrolyte solution can also optionally include an additive. For example, the additive can include a negative electrode film-forming additive, a positive electrode film-forming additive, and can also include an additive capable of improving certain performance of the battery, such as an additive capable of improving overcharge performance of the battery, an additive capable of improving high-temperature or low-temperature performance of the battery, etc.

[0123] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator film can be made into an electrode assembly through a roll-pressing process or a stacking process.

[0124] In some embodiments, the battery cell can include an outer package. The outer package can be used to package the electrode assembly and the electrolyte solution described above.

[0125] In some embodiments, the outer package of the battery cell can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package of the battery cell can also be a soft package, such as a pouch-type soft package. The material of the soft package can be plastic, and as plastic, polypropylene, polybutylene terephthalate, and polybutylene succinate, etc. can be listed.

[0126] The shape of the battery cell is not particularly limited in the present application, and can be cylindrical, square, or any other arbitrary shape. For example, Figure 3 is a battery cell 5 of a square structure as an example.

[0127] In some embodiments, with reference to Figure 4The outer package can include a housing 51 and a top cover assembly 53. The housing 51 can include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose a receiving cavity. The housing 51 has an opening in communication with the receiving cavity, and the top cover assembly 53 can be covered on the opening to close the receiving cavity. The positive electrode tab, the negative electrode tab, and the separator film can form the electrode assembly 52 through a winding process or a stacking process. The electrode assembly 52 is packaged in the receiving cavity. The electrolyte is impregnated in the electrode assembly 52. The number of electrode assemblies 52 contained in the battery cell 5 can be one or more, and the number can be selected by a person skilled in the art according to the actual needs.

[0128] In some embodiments, the battery cell can be assembled into a battery module, and the number of battery cells contained in the battery module can be one or more, and the specific number can be selected by a person skilled in the art according to the application and capacity of the battery module.

[0129] Figure 5 The battery module 4 is an example. Refer to Figure 5 In the battery module 4, a plurality of battery cells 5 can be arranged in sequence along the length direction of the battery module 4. Of course, other arbitrary arrangements can also be used. Further, the plurality of battery cells 5 can be fixed by fasteners.

[0130] Optionally, the battery module 4 can further include a housing having a receiving space, and the plurality of battery cells 5 are received in the receiving space.

[0131] In some embodiments, the above-mentioned battery module can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, and the specific number can be selected by a person skilled in the art according to the application and capacity of the battery pack.

[0132] Figure 6 and Figure 7 The battery pack 1 is an example. Refer to Figure 6 and Figure 7 The battery pack 1 can include a battery box and a plurality of battery modules 4 arranged in the battery box. The battery box includes an upper box body 2 and a lower box body 3, and the upper box body 2 can be covered on the lower box body 3 to form a closed space for receiving the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0133] Electric device

[0134] In addition, the second aspect of the present application provides a power consuming device comprising the secondary battery provided by the present application. The secondary battery can be used as a power source of the power consuming device, or can be used as an energy storage unit of the power consuming device. The power consuming device can include a mobile device (such as a mobile phone, a notebook computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship and a satellite, an energy storage system, etc., but is not limited thereto.

[0135] As the power consuming device, the battery monomer, the battery module or the battery pack can be selected according to the use requirement thereof.

[0136] Figure 8 The power consuming device is taken as an example. The power consuming device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the requirement of high power and high energy density of the secondary battery for the power consuming device, the battery pack or the battery module can be used.

[0137] The device taken as another example can be a mobile phone, a tablet computer, a notebook computer, etc. The device usually requires thinning, and the battery monomer can be used as a power source.

[0138] Separator film

[0139] The third aspect of the present application provides a separator film comprising a composite substrate layer and a grid-shaped adhesive layer. The composite substrate layer comprises at least two base films and at least a solid electrolyte layer arranged between each two base films; the grid-shaped adhesive layer is arranged on at least one side of the composite substrate layer.

[0140] In the present application, since the separator film comprises at least two base films, the at least two base films can be closed at the same time in a high temperature environment, which can block the transmission path of active ions sufficiently, thereby improving the safety performance of the battery; in addition, the transmission efficiency of active ions can be improved by arranging the solid electrolyte layer in the separator film, thereby being beneficial to reduce the internal resistance of the secondary battery. On this basis, the adhesive layer is arranged in a grid shape, which can reduce the contact area between the adhesive layer and the pole piece, i.e. reduce the influence of the adhesive layer on the internal resistance of the secondary battery, which can reduce the internal resistance of the secondary battery on the basis of realizing the adhesion between the separator film and the pole piece. Based on the above analysis, the separator film of the present application can take into account high safety performance and low internal resistance.

[0141] The present application does not particularly limit the number of base films included in the composite substrate layer. For example, the number of base films included in the composite substrate layer can be 2, 3, 4, and more.

[0142] In some embodiments, the isolation film further comprises a heat-resistant layer, which is arranged at least between the composite matrix layer and the grid-shaped adhesive layer. In some embodiments, the heat-resistant layer can also be arranged between one base film in the composite matrix layer and the solid-state electrolyte layer, or between two base films in the composite matrix layer and the solid-state electrolyte layer, or between the composite matrix layer away from the grid-shaped adhesive layer when the grid-shaped adhesive layer is arranged on one side of the composite matrix layer. In the present application, the heat-resistant layer can protect the composite matrix layer, reduce the probability of performance degradation of the composite matrix layer due to excessive temperature, and further improve the safety performance of the isolation film.

[0143] The present application does not particularly limit the number of base films 111 included in the composite matrix layer 11. For example, the number of base films included in the composite matrix layer can be 2, 3, 4, and more.

[0144] In some embodiments, the composite matrix layer includes two base films and a solid-state electrolyte layer between the two base films. By arranging the solid-state electrolyte layer between the base films, the internal resistance of the battery can be further reduced.

[0145] In some embodiments, the composite matrix layer includes two base films and a solid-state electrolyte layer between the two base films and on the outer surfaces of the two base films, i.e., the composite matrix layer includes three solid-state electrolyte layers and two base film layers, and the solid-state electrolyte layers and the base film layers are arranged alternately. In this way, the internal resistance of the battery can be further reduced.

[0146] In some embodiments, the porosity of the base film is 45% to 55%. For example, the porosity of the base film is 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, or a value within the range between any two of the above values. Controlling the porosity of the base film within the above range can improve the air permeability of the isolation film and further reduce the internal resistance of the battery.

[0147] In some embodiments, the materials of the at least two base films are the same or different. Using the same material for the at least two base films can simplify the structure of the isolation film. Using different materials for the at least two base films can achieve differentiated settings of the isolation film, which can more fully block the transmission path of active ions and thus improve the safety performance of the battery.

[0148] In some embodiments, the base film comprises one or more of a polyethylene base film, a polypropylene base film, a polyethylene-polypropylene composite base film, a polyethylene non-woven base film, a polypropylene non-woven base film, a polypropylene-polyethylene-polypropylene composite base film, a polyimide base film, a polyimide non-woven base film, a polytetrafluoroethylene base film, a polytetrafluoroethylene non-woven base film, a polyvinyl chloride base film, or a polyvinyl chloride non-woven base film. The above-mentioned base films have the advantages of low cost, stable chemical properties, excellent mechanical properties, and the like, and are conducive to improving the chemical stability and mechanical properties of the separator film.

[0149] In some embodiments, the thickness of the base film is 5 μm to 15 μm. Illustratively, the thickness of the base film is 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, or a value between any two of the above-mentioned values. The thickness of the base film is in the above-mentioned range, so that the separator film has suitable mechanical stability and chemical stability, which is conducive to balancing the high safety performance and low internal resistance of the battery.

[0150] In some embodiments, the grid width of the grid-shaped adhesive layer is 200 μm to 500 μm. Illustratively, the grid width of the grid-shaped adhesive layer is 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm, or a value between any two of the above-mentioned values. The grid width of the grid-shaped adhesive layer is in the above-mentioned range, which can reduce the internal resistance of the secondary battery on the basis of realizing the adhesion between the separator film and the pole piece.

[0151] In some embodiments, the spacing between the two adjacent grids of the grid-shaped adhesive layer is 1000 μm to 5000 μm. Illustratively, the spacing between the two adjacent grids is 1000 μm, 2000 μm, 3000 μm, 4000 μm, 5000 μm, or a value between any two of the above-mentioned values. The spacing between the two adjacent grids of the grid-shaped adhesive layer is in the above-mentioned range, which can further reduce the internal resistance of the secondary battery on the basis of realizing the adhesion between the separator film and the pole piece.

[0152] In some embodiments, the thickness of the grid-shaped adhesive layer is 0.4 μm to 1 μm. Illustratively, the thickness of the grid-shaped adhesive layer is 0.4 μm, 0.6 μm, 0.8 μm, 1 μm, or a value between any two of the above-mentioned values. The thickness of the grid-shaped adhesive layer is in the above-mentioned range, which can further reduce the internal resistance of the battery on the basis of realizing the adhesion between the separator film and the pole piece.

[0153] In some embodiments, the solid-state electrolyte layer comprises a first electrolyte material, a first ceramic material and a first binder; the mass ratio of the first electrolyte material, the first ceramic material and the first binder is (4-9):(0-4):(1-2). The mass ratio of the first electrolyte material, the first ceramic material and the first binder within the above range is conducive to further reducing the ion impedance of the isolation film, thereby further reducing the internal resistance of the battery. In addition, in the present application, by introducing the first ceramic material into the solid-state electrolyte layer, the heat resistance of the isolation film can be improved, which is conducive to further improving the safety performance.

[0154] In some embodiments, the first electrolyte material comprises one or more of LGLZO (lithium garnet zirconium oxide), LiGe2(PO4)3 (lithium germanium phosphate), LZTO (lithium zirconium titanium oxide), LLTO (lithium lanthanum titanium oxide), LiT2(PO4)3 (lithium titanium phosphate), LLZO (lithium lanthanum zirconium oxide), LATP (lithium aluminum titanium phosphate), LAGP (lithium aluminum germanium phosphate), LLAZO (lithium lanthanum aluminum zirconium oxide). The above-mentioned first electrolyte material has the advantage of high ion migration coefficient, and is used as the main material of the solid-state electrolyte layer, which can further reduce the internal resistance of the battery.

[0155] In some embodiments, the first ceramic material comprises one or more of boehmite, aluminum oxide, magnesium hydroxide, magnesium oxide, barium titanate, zinc oxide or barium sulfate.

[0156] In some embodiments, the first binder comprises one or more of polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl alcohol, polyurethane or polystyrene acid.

[0157] In some embodiments, the thickness of the solid-state electrolyte layer is 1-5 μm. For example, the thickness of the solid-state electrolyte layer is 1 μm, 2 μm, 3 μm, 4 μm, 5 μm or a value between any two of the above values. The thickness of the solid-state electrolyte layer within the above range is conducive to further reducing the internal resistance of the battery.

[0158] In some embodiments, the heat-resistant layer comprises a second ceramic material, a second electrolyte material and a second binder; the mass ratio of the second ceramic material, the second electrolyte material and the second binder is:

[0159] (4-9):(0-4):(1-2). The mass ratio of the second ceramic material, the second electrolyte material and the second binder within the above range is conducive to improving the safety performance of the battery. In addition, by mixing the second solid-state electrolyte material in the heat-resistant layer, the heat resistance of the isolation film can be improved, and the influence of the heat-resistant layer on the internal resistance of the battery can be reduced, i.e. the internal resistance of the battery is further reduced.

[0160] In some embodiments, the second ceramic material includes one or more of boehmite, alumina, magnesium hydroxide, magnesium oxide, barium titanate, zinc oxide, or barium sulfate. The above-mentioned second ceramic material has the advantages of good flame-retardant effect, good chemical stability, good thermal stability, etc., and is used as the main material of the heat-resistant layer, which is conducive to further improving the safety performance of the battery.

[0161] In some embodiments, the second electrolyte material includes one or more of LGLZO, LiGe2(PO4)3, LZTO (lithium zirconium titanate), LLTO (lithium lanthanum titanate), LiT2(PO4)3, LLZO (lithium lanthanum zirconate), LATP (lithium aluminum titanium phosphate), LAGP (lithium aluminum silicon phosphate), and LLAZO (lithium lanthanum aluminum zirconium oxide).

[0162] In some embodiments, the second binder includes one or more of polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl alcohol, polyurethane, or polystyrene acrylate.

[0163] In some embodiments, the thickness of the heat-resistant layer is 0.5 μm to 2 μm. Illustratively, the thickness of the heat-resistant layer is 0.5 μm, 1 μm, 1.5 μm, 2 μm, or a value between any two of the above values. The thickness of the heat-resistant layer in the above range can balance the safety performance and low internal resistance of the battery.

[0164] Method for preparing a separator film

[0165] The fourth aspect of the present application provides a method for preparing a separator film, including: a first preparation step, including forming a solid electrolyte layer on at least one surface of a base film, and then combining another base film on the surface of the solid electrolyte layer to form a composite base layer; and a second preparation step, including forming a grid-shaped adhesive layer on at least one side surface of the composite base layer.

[0166] In the present application, by forming a composite base layer including at least two base films and at least a solid electrolyte layer arranged between each two base films, and forming a grid-shaped adhesive layer on at least one side surface of the composite base layer, a separator film with high safety performance and low internal resistance can be obtained.

[0167] The isolation film formed by the application can sufficiently block the transmission path of active ions by closing the pores of the at least two base films at the same time in a high-temperature environment, thereby improving the safety performance of the battery. In addition, the transmission efficiency of active ions can be improved by arranging the solid-state electrolyte layer in the isolation film, thereby facilitating the reduction of the internal resistance of the secondary battery. On this basis, the adhesive layer is arranged in a grid shape, which can reduce the contact area between the adhesive layer and the pole piece, i.e., reduce the influence of the adhesive layer on the internal resistance of the secondary battery, and can reduce the internal resistance of the secondary battery on the basis of realizing the adhesion between the isolation film and the pole piece. Based on the above analysis, the isolation film of the application can balance high safety performance and low internal resistance.

[0168] In some embodiments, in the second preparation step, the adhesive layer slurry is coated by using a grid structure gravure roll to form a grid-shaped adhesive layer. Coating the adhesive layer slurry by using a grid structure gravure roll can obtain a grid-shaped adhesive layer, thereby reducing the internal resistance of the secondary battery on the basis of realizing the adhesion between the isolation film and the pole piece.

[0169] In some embodiments, in the first preparation step, the first slurry is coated on the surface of at least one base film by using a roll coating method to form a solid-state electrolyte layer. Optionally, after the surface of the solid-state electrolyte layer is compounded with another base film in the first preparation step, the compound base layer is subjected to drying treatment at 40-90°C for 1-3 min. Forming the compound base layer under the above conditions is conducive to forming a compound base layer with appropriate thickness and uniformity, thereby facilitating the balance between high safety performance and low internal resistance of the battery.

[0170] In some embodiments, the first slurry is configured by: adding the first electrolyte material, the first ceramic material, and the first binder according to the mass ratio (4-9):(0-4):(1-2) into the first solvent and mixing them thoroughly to form the first slurry with a solid content of 40-44%. The first solvent includes one or more of N,N dimethylformamide, N-methyl pyrrolidone, dimethyl sulfoxide, acetonitrile, or ethanol.

[0171] In some embodiments, the above first preparation step further includes coating the second slurry on at least one side of the compound base layer to form a heat-resistant layer. In this way, it is conducive to further improving the safety performance of the isolation film.

[0172] In some embodiments, in the step of forming the heat-resistant layer, the second slurry is coated on the surface of at least one side of the compound base layer and then subjected to drying treatment, which is optionally performed at 40-90°C for 1-3 min. Forming the heat-resistant layer under the above conditions is conducive to forming a heat-resistant layer with appropriate thickness and uniformity, thereby facilitating the improvement of the safety performance of the battery.

[0173] In some embodiments, the second slurry is prepared by mixing the second ceramic material, the second electrolyte material and the second binder in a mass ratio of (4-9):(0-4):(1-2) in a second solvent and stirring sufficiently to form a second slurry with a solid content of 9-11%. The second solvent includes one or more of N,N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, acetonitrile or ethanol.

[0174] Examples

[0175] Hereinafter, examples of the present application will be described. The examples described below are illustrative and are presented for the purpose of explanation only and are not to be construed as limiting the present application. In the examples, unless otherwise specified, the techniques or conditions are performed according to the techniques or conditions described in the literature in the art or according to the product manual. Unless otherwise specified, the reagents or instruments used are all conventional products that can be obtained commercially.

[0176] Example 1

[0177] Preparation of the separator film

[0178] First preparation step, a) slurry preparation step: the first solid electrolyte LATP (Tianmu Pioneer), the first ceramic material boehmite (Yishitong), and the first binder PVDF were added to a solvent N-methylpyrrolidone in a weight ratio of 9:0:1, and stirred sufficiently to form a first slurry A with a solid content of 42%; the binder PVDF was added to a solvent N-methylpyrrolidone and stirred sufficiently to form a binder layer slurry C with a solid content of 10%.

[0179] b) coating step: a single layer of polyethylene release film (Zuogao) with a porosity of 50% and a thickness of 7 μm was taken as a base film 1, and the first slurry A was coated on the surface of the base film 1 by roll coating, and then another single layer of polyethylene release film (Zuogao) with a porosity of 50% and a thickness of 7 μm was taken as a base film 2, and was combined with the first slurry, and then the whole was dried at a temperature of 80°C for 30 min to form a composite base layer, in which the thickness of the solid electrolyte was 3 μm, and the thickness of the whole composite base layer was 17 μm.

[0180] Second preparation step: the binder layer slurry C was coated on the upper and lower surfaces of the composite base layer using a grid structure gravure roll, and after drying, a grid-shaped binder layer was obtained, with a thickness of 1 μm, a grid width of 300 μm, and a spacing between adjacent two grids of 2000 μm.

[0181] Performance test of the separator film

[0182] Test of air permeability

[0183] The isolation film prepared in Example 1 was fixed, air pressure was applied to one side of the isolation film, and air pressure drop and time used were tested to detect the air permeability of the isolation film. Specifically, the area of 6.45 cm 2 The time required for the isolation film, which is the air permeability of the isolation film, is shown in Table 2.

[0184] Preparation of the positive electrode sheet

[0185] The positive active material lithium iron phosphate, the binder PVDF, and the conductive agent Super P were added to an appropriate amount of solvent NMP in a mass ratio of 96.5:1.5:2, stirred and mixed to obtain a positive electrode slurry. The slurry was coated on the surface of the positive electrode current collector to form a positive electrode film layer, and the positive electrode film layer was subjected to drying, cold pressing and other processes to obtain a positive electrode sheet.

[0186] Preparation of the negative electrode sheet

[0187] The negative active material graphite, the binder styrene-butadiene rubber, the thickening agent CMC, and the conductive agent acetylene black were added to an appropriate amount of solvent deionized water in a mass ratio of 97:1:0.8:1.2, stirred and mixed to obtain a negative electrode slurry. The slurry was coated on the surface of the negative electrode current collector copper foil to form a negative electrode film layer, and the negative electrode film layer was subjected to drying, cold pressing and other processes to obtain a negative electrode sheet.

[0188] Electrolyte

[0189] Vinyl carbonate (EC) and diethyl carbonate (DEC) were mixed in a mass ratio of 3:7 to obtain an organic solvent, and then LiPF6 was dissolved in the organic solvent to prepare an electrolyte with a concentration of 1.2 mol / L.

[0190] Preparation of the secondary battery

[0191] The positive electrode sheet, the isolation film, and the negative electrode sheet were stacked in order, with the isolation film between the positive electrode sheet and the negative electrode sheet to play a role of isolation, and the stack was obtained as a bare cell. The bare cell was placed in an outer package, injected with the prepared electrolyte and packaged to obtain a secondary battery.

[0192] Performance test of the secondary battery

[0193] 1) DC internal resistance (DCR) test

[0194] ① At 25°C, constant current charging to 4.2V at a current of 0.33C, and then constant voltage charging to 0.05C;

[0195] ② Discharge to 50% capacity at a current of 0.33C to adjust the state of the battery to 50% SOC.

[0196] ③ rest for 5h at 25°C;

[0197] ④ constant current discharge at 2C for 10s, record the voltage of the battery before discharge V1 and the voltage of the battery after discharge V2;

[0198] DCR = (V2-V1) / 2C, the test results are shown in Table 2.

[0199] 2) cycle performance test

[0200] ① constant current charge to 4.2V at 1C, then constant voltage charge to 4.2V until the current is 0.05C;

[0201] ② rest for 30min;

[0202] ③ constant current discharge to 2.5V at 1C, record the discharge capacity of the 1st cycle D1;

[0203] ④ rest for 30min;

[0204] ⑤ cycle the above steps ① to ④ for 200 times, record the discharge capacity of the 200th cycle D 200 .

[0205] 200 cycle capacity retention rate (%) = discharge capacity of the 200th cycle D 200 / discharge capacity of the 1st cycle D1*100%, the test results are shown in Table 2.

[0206] 3) safety performance test

[0207] After the secondary battery is fully charged, it is placed in a hot box, and the temperature is increased from room temperature to 150°C at a rate of 5°C / min and kept for 30min. If the secondary battery does not catch fire or explode during this process, it is considered to have passed the safety performance test, recorded as pass, if the secondary battery catches fire or explodes during this process, it is considered to have failed the safety performance test, recorded as NG, the experimental results are shown in Table 2.

[0208] Example 2

[0209] The separator film was prepared according to the method similar to that of Example 1, and assembled into a secondary battery, with the difference that the separator film was prepared by further including the steps of disposing and coating the second slurry B, specifically, the second ceramic powder boehmite (Biyuntong), the second solid-state electrolyte LATP (Tianmuying), and the second binder PVDF were added into the solvent NMP at a weight ratio of 7:2:1, and mixed by stirring to form the second slurry B with a solid content of 40%; the second slurry B was coated on the upper and lower surfaces of the composite substrate layer, respectively, and then dried at a temperature of 80°C for 20 min to form a heat-resistant layer with a thickness of 2 μm, and then the grid-shaped adhesive layer was formed on the heat-resistant layer in the same manner as in Example 1.

[0210] The parameters of the prepared separator film are shown in Table 1 below.

[0211] Comparative Examples 1-4

[0212] The separator film was prepared according to the method similar to that of Example 1, and assembled into a secondary battery, with the difference that the parameters of the prepared separator film are shown in Table 1 below.

[0213] Table 1 shows the parameters of the prepared separator films in Example 1 and 2, and Comparative Examples 1-4. Table 2 shows the performance parameters of the prepared separator films in Example 1 and 2, and Comparative Examples 1-4, and the performance test results of the secondary batteries.

[0214] Table 1

[0215]

[0216] " / " in Table 1 indicates the absence.

[0217] Table 2

[0218]

[0219] As can be seen from Table 1 and Table 2, compared with Comparative Example 1 (only one base film is provided) and Comparative Example 4, by providing the separator film including two base films in Example 1 and 2, the safety performance of the secondary battery is obviously improved, and the air permeability of the separator film is basically flat; compared with Comparative Example 2 (without solid-state electrolyte layer) and Comparative Example 4, by providing the solid-state electrolyte layer between the two base films, the internal resistance of the secondary battery is obviously reduced; compared with Comparative Example 3 (the shape of the adhesive layer is sheet-shaped) and Comparative Example 4, by providing the adhesive layer in a grid shape in Example 1 and 2, the internal resistance of the secondary battery is further reduced, and providing the adhesive layer in a grid shape does not affect the adhesion performance, and the cycle retention rate of the secondary battery is not lost. Therefore, by providing the separator film including two base films and a solid-state electrolyte layer, and providing the adhesive layer in a grid shape in Example 1 and 2, the safety performance of the secondary battery is obviously improved, and the internal resistance of the secondary battery is reduced without affecting the adhesion performance.

[0220] Examples 3 to 7

[0221] The separator films were prepared in a similar manner to Example 2 and assembled into secondary batteries, with the only difference being that the parameters were adjusted according to Table 3 and Table 4 below when preparing the separator films, and the parameters of the prepared separator films and secondary batteries are shown in Table 5 below.

[0222] Table 3 and Table 4 below show the characteristics of the separator films prepared in Examples 3 to 7. Table 5 below shows the parameters of the separator films prepared in Examples 3 to 7 and the performance test parameters of the secondary batteries.

[0223] Table 3

[0224]

[0225]

[0226] Table 4

[0227]

[0228] Table 5

[0229]

[0230] As can be seen from Table 3-5, by setting the porosity of the base film to 45% to 55%, setting the thickness of the base film to 5 μm to 15 μm, setting the grid width of the adhesive layer to 200 μm to 500 μm, setting the grid thickness of the adhesive layer to 1000 μm to 5000 μm, and setting the mass ratio of the first electrolyte material, the first ceramic material and the first binder in the solid electrolyte layer to (4 to 9):(0 to 4):(1 to 2), the internal resistance of the secondary battery is significantly reduced, and the safety performance of the secondary battery is improved.

[0231] It should be noted that the present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and embodiments having substantially the same configuration and playing the same role and effect as the technical idea within the scope of the technical solution of the present application are all included in the technical scope of the present application. Furthermore, within the scope of the main idea of the present application, various modifications that can be thought of by those skilled in the art, other modes constructed by combining part of the configuration elements of the embodiments are also included in the scope of the present application.

Claims

1. A secondary battery characterized by comprising: The separator film comprises: The composite matrix layer comprises at least two base films and at least a solid electrolyte layer arranged between each two base films; The grid-shaped adhesive layer is arranged on at least one side of the composite matrix layer.

2. The secondary battery according to claim 1, characterized by The separator film further comprises a heat-resistant layer. The heat-resistant layer is arranged between the composite matrix layer and the grid-shaped adhesive layer.

3. The secondary battery according to claim 1 or 2, characterized by The composite matrix layer comprises two base films and the solid electrolyte layer arranged between the two base films.

4. The secondary battery according to any one of claims 1 to 3, characterized by, The porosity of the base film is 45% to 55%.

5. The secondary battery according to any one of claims 1 to 4, characterized by, The material of the at least two base films is the same or different.

6. The secondary battery according to any one of claims 1 to 5, characterized by The base film comprises one or more of a polyethylene-based film, a polypropylene-based film, a polyethylene-polypropylene composite-based film, a polyethylene non-woven fabric-based film, a polypropylene non-woven fabric-based film, a polypropylene-polyethylene-polypropylene composite-based film, a polyimide-based film, a polyimide non-woven fabric-based film, a polytetrafluoroethylene-based film, a polytetrafluoroethylene non-woven fabric-based film, a polyvinyl chloride-based film, or a polyvinyl chloride non-woven fabric-based film.

7. The secondary battery according to any one of claims 1 to 6, characterized by The thickness of the base film is 5 to 15 microns.

8. The secondary battery according to any one of claims 1 to 7, characterized by, The grid width of the grid-shaped adhesive layer is 200 to 500 microns.

9. The secondary battery according to any one of claims 1 to 8, characterized by, The spacing between adjacent two grids of the grid-shaped adhesive layer is 1000 to 5000 microns.

10. The secondary battery according to any one of claims 1 to 9, characterized by The thickness of the grid-shaped adhesive layer is 0.4 to 1 micron.

11. The secondary battery according to any one of claims 1 to 10, characterized by The solid electrolyte layer comprises a first electrolyte material, a first ceramic material, and a first adhesive; the mass ratio of the first electrolyte material, the first ceramic material, and the first adhesive is (4-9):(0-4):(1-2).

12. The secondary battery according to claim 11, characterized by The first electrolyte material comprises one or more of LGLZO, LiGe2(PO4)3, LZTO, LLTO, LiT2(PO4)3, LLZO, LATP, LAGP, and LLAZO.

13. The secondary battery according to any one of claims 1 to 12, characterized by, The thickness of the solid electrolyte layer is 1 to 5 microns.

14. The secondary battery according to claim 2, characterized by The heat-resistant layer comprises a second ceramic material, a second electrolyte material, and a second adhesive; the mass ratio of the second ceramic material, the second electrolyte material, and the second adhesive is (4-9):(0-4):(1-2).

15. The secondary battery according to claim 14, characterized by The second ceramic material comprises one or more of boehmite, aluminum oxide, magnesium hydroxide, magnesium oxide, barium titanate, zinc oxide, or barium sulfate.

16. The secondary battery according to claim 14 or 15, characterized by The thickness of the heat-resistant layer is 0.5 to 2 microns.

17. An electrical device, comprising: The secondary battery comprises any one of claims 1 to 16.

18. An isolating film, characterized by, The separator film comprises: The composite matrix layer comprises at least two base films and at least a solid electrolyte layer arranged between each two base films; The grid-shaped adhesive layer is arranged on at least one side of the composite matrix layer.

19. The separator membrane of claim 18, wherein, The separator film further comprises: The heat-resistant layer; The heat-resistant layer is arranged between the composite matrix layer and the grid-shaped adhesive layer.

20. The separator membrane according to claim 18 or 19, characterized in that, The porosity of the base film is 45% to 55%.

21. The separator membrane according to any one of claims 18 to 20, characterized in that, The thickness of the base film is 5 to 15 microns.

22. The separator membrane according to any one of claims 18 to 21, characterized in that, The grid width of the grid-shaped adhesive layer is 200 to 500 microns.

23. The separator membrane according to any one of claims 18 to 22, characterized in that, The spacing between adjacent two grids of the grid-shaped adhesive layer is 1000 to 5000 microns.

24. The separator membrane according to any one of claims 18 to 23, characterized in that, The thickness of the grid-shaped adhesive layer is 0.4 to 1 micron.

25. The separator membrane according to any one of claims 18 to 24, characterized in that, The solid electrolyte layer comprises a first electrolyte material, a first ceramic material and a first binder; the mass ratio of the first electrolyte material, the first ceramic material and the first binder is (4-9):(0-4):(1-2).

26. The separator membrane according to any one of claims 18 to 25, characterized in that, The thickness of the solid electrolyte layer is 1-5 μm.

27. The separator membrane of claim 19, wherein, The heat-resistant layer comprises a second ceramic material, a second electrolyte material and a second binder; the mass ratio of the second ceramic material, the second electrolyte material and the second binder is (4-9):(0-4):(1-2).

28. The separator membrane of claim 19 or 27, wherein, The thickness of the heat-resistant layer is 0.5-2 μm.

29. A method of producing an isolating film, characterized by, The method comprises the following steps: The first preparation step comprises forming a solid electrolyte layer on at least one surface of a base film, and then compounding another base film on the surface of the solid electrolyte layer to form a compound base layer; The second preparation step comprises forming a grid-shaped adhesive layer on at least one surface of the compound base layer.

30. The method of claim 29, wherein, In the second preparation step, the grid structure gravure roll is used to coat the adhesive layer slurry to form the grid-shaped adhesive layer.

31. The method of manufacturing according to claim 29 or 30, wherein, In the first preparation step, the first slurry is coated on at least one surface of a base film by roll coating to form the solid electrolyte layer.

32. The method of any one of claims 30-31, wherein, In the first preparation step, after compounding another base film on the surface of the solid electrolyte layer, drying treatment is performed at 40-90 °C for 1-3 min.

33. The method of manufacturing according to any one of claims 30 to 32, wherein, The first preparation step further comprises coating a second slurry on at least one side of the compound base layer to form a heat-resistant layer.

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