Diaphragm, sodium ion battery and electric device

Abstract

The utility model relates to a diaphragm, a sodium ion battery and an electric device. The diaphragm is used for the sodium ion battery and comprises a diaphragm base material; the first functional layer is arranged on one side, close to the negative electrode of the sodium ion battery, of the diaphragm base material, and the first functional layer comprises a first gas adsorption layer and a first water absorption layer which are sequentially stacked on the diaphragm base material; the second functional layer is arranged on the side, close to the positive electrode of the sodium ion battery, of the diaphragm base material, and the second functional layer comprises a second water absorption layer, a sodium supplementing layer and a second gas adsorption layer which are sequentially arranged on the diaphragm base material in a stacked mode. According to the diaphragm provided by the invention, the sodium supplementing layer, the first gas adsorption layer, the second gas adsorption layer, the first water absorption layer and the second water absorption layer are arranged, and the position of the layered structure is reasonably configured, so that the energy density, the first coulombic efficiency and the structural stability of the sodium ion battery are improved, and the cycle life of the sodium ion battery is prolonged.

Description

Technical Field

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

[0002] Sodium-ion batteries have been widely used in energy storage and other fields due to their advantages such as rich resources, low price, and wide distribution.

[0003] However, during the first charge and discharge process, side reactions occur on the positive electrode side of the sodium-ion battery, consuming some active sodium, and on the negative electrode side, the formation of the SEI film also consumes some active sodium. Therefore, the energy density of the sodium-ion battery is reduced, resulting in a low Coulombic efficiency of the sodium-ion battery during the first charge and discharge.

[0004] During the production and manufacturing process of sodium-ion batteries, the moisture in the electrode sheet is usually controlled within a few hundred ppm, and the moisture in the electrolyte is controlled within dozens of ppm. Among them, since the solvent in the negative electrode slurry is water, the moisture in the negative electrode sheet after coating is higher than that in the positive electrode sheet. The trace moisture remaining inside the sodium-ion battery will still trigger side reactions, accelerating the attenuation of the battery capacity during the cycling process and storage process. In addition, a certain amount of gas is released during the cycling process of the sodium-ion battery, which causes the interface to deteriorate due to swelling, further exacerbating the failure of the battery.

[0005] In addition, layered oxides, as the positive electrode material of sodium-ion batteries, have received extensive attention due to their high energy density and good rate performance. However, layered oxides have problems such as unstable interfaces and poor air stability during the charge and discharge process, and will undergo a hydration reaction with water molecules to form a hydrated phase, affecting the structural stability and electrochemical performance of the material. Summary of the Utility Model

[0006] Based on this, it is necessary to provide a separator, a sodium-ion battery, and an electrical device to solve the above technical problems.

[0007] In the first aspect of the present application, a separator is provided. The separator is used for a sodium-ion battery and includes: a separator substrate; a first functional layer disposed on one side of the separator substrate close to the negative electrode of the sodium-ion battery, the first functional layer including a first gas adsorption layer and a first water absorption layer sequentially stacked on the separator substrate; a second functional layer disposed on one side of the separator substrate close to the positive electrode of the sodium-ion battery, the second functional layer including a second water absorption layer, a sodium supplement layer, and a second gas adsorption layer sequentially stacked on the separator substrate.

[0008] In some embodiments, the thickness ratio of the first gas adsorption layer to the second gas adsorption layer is (1~1.5):1.

[0009] In some embodiments, the thickness of the first gas adsorption layer is 0.3μm~5μm.

[0010] In some embodiments, the thickness ratio of the first water-absorbing layer to the second water-absorbing layer is (1~1.5):1.

[0011] In some embodiments, the thickness of the second water-absorbing layer is 0.1 μm to 2 μm.

[0012] In some embodiments, the thickness of the sodium supplement layer is 0.1 μm to 3 μm.

[0013] In some embodiments, the sodium supplement layer is a discontinuous coating structure, and the discontinuous coating structure includes a coating area and a gap area, and the width of the gap area is 1 / 5 to 1 / 4 of the width of the coating area.

[0014] In some embodiments, the first gas adsorption layer and the second gas adsorption layer are metal-organic framework layers.

[0015] In some embodiments, the first water-absorbing layer and the second water-absorbing layer are the same or different, and are independently selected from any one of a calcium chloride layer, an aluminum chloride layer, a magnesium sulfate layer, and an activated carbon layer.

[0016] In some embodiments, the sodium supplement layer is selected from any one of a sodium azide layer, a sodium carbonate layer, a sodium nitrite layer, a sodium oxide layer, a sodium peroxide layer, a sodium oxalate layer, a sodium squarate layer, a tetrasodium ethylenediaminetetraacetate layer, and a pentasodium diethylenetriaminepentaacetate layer.

[0017] The second aspect of the present application provides a sodium-ion battery, which includes a positive electrode, a negative electrode, and the separator provided in the first aspect above, and the positive electrode is a layered oxide positive electrode.

[0018] The third aspect of the present application provides an electrical device, which includes the sodium-ion battery provided in the second aspect above.

[0019] Compared with the traditional technology, the present application has at least the following beneficial effects:

[0020] For the separator provided in this application, the first functional layer is disposed closer to the negative electrode side of the sodium-ion battery, and the second functional layer is disposed closer to the positive electrode side of the sodium-ion battery. On the one hand, the applicant has found that in actual production, the moisture content of the negative electrode tab is higher than that of the positive electrode tab. Therefore, the first water absorption layer is disposed at a position far from the separator substrate and close to the negative electrode, and the second water absorption layer is disposed at a position close to the separator substrate and far from the positive electrode, thereby slowing down the damage of water molecules in the battery to the positive electrode material and ensuring the structural stability and electrochemical performance of the positive electrode material. On the other hand, the sodium supplementation layer in the second functional layer provides an additional sodium source, improving the energy density and first Coulombic efficiency of the sodium-ion battery. The first gas adsorption layer is disposed at a position close to the separator substrate and far from the negative electrode, and the second gas adsorption layer is disposed between the sodium supplementation layer and the positive electrode. It can not only adsorb the gas generated during the cycling of the battery together with the first gas adsorption layer, but also in-situ adsorb the gas released during the sodium supplementation process of the sodium supplementation layer, slowing down the damage of the gas to the battery interface and improving the cycle life of the battery.

[0021] In summary, for the separator provided in this application, by setting the sodium supplementation layer, the first gas adsorption layer, the second gas adsorption layer, the first water absorption layer and the second water absorption layer and reasonably configuring the positions of the above-layered structures, the energy density, first Coulombic efficiency, structural stability and cycle life of the sodium-ion battery are improved. Description of the Drawings

[0022] Figure 1 It is a schematic structural diagram of the separator in an embodiment of this application.

[0023] Description of the Reference Numerals

[0024] 1. Separator;

[0025] 10. Separator Substrate;

[0026] 20. First Functional Layer; 21. First Gas Adsorption Layer; 22. First Water Absorption Layer;

[0027] 30. Second Functional Layer; 31. Second Water Absorption Layer; 32. Sodium Supplementation Layer; 33. Second Gas Adsorption Layer. Detailed Description of the Embodiments

[0028] To make the above objects, features and advantages of this application more obvious and understandable, the following detailed description of the specific embodiments of this application is provided in conjunction with the drawings. Many specific details are set forth in the following description in order to fully understand this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of this application. Therefore, this application is not limited by the specific embodiments disclosed below.

[0029] In the description of the present application, it should be understood that if there are terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., the orientation or positional relationship indicated by these terms is based on the orientation or positional relationship shown in the drawings. These are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present application.

[0030] In addition, if there are terms such as "first" and "second", these terms are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present application, if there is a term "plurality", the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0031] In the present application, unless otherwise clearly specified and limited, if there are terms such as "mounted", "connected", "connected to", "fixed", etc., these terms should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0032] In the present application, unless otherwise clearly specified and limited, if there is a description such as a first feature being "on" or "under" a second feature, the meaning may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. The first feature being "under", "beneath" and "underneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0033] It should be noted that if an element is referred to as "fixed to" or "disposed on" another element, it can be directly on the other element or there may also be an intermediate element. If an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. If present, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are only for illustrative purposes and do not represent the only implementation.

[0034] In this application, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are considered continuous and include the minimum and maximum values of the range, as well as every value between such minimum and maximum values. Further, when the range refers to integers, it includes every integer between the minimum and maximum values of the range. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.

[0035] If there is no special instruction, the "including" and "comprising" mentioned in this application mean open-ended, and can also be closed-ended. For example, the "including" and "comprising" can mean that other components not listed can also be included or comprised, or only the components listed are included or comprised.

[0036] If there is no special instruction, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) while B is true (or exists); or both A and B are true (or exist).

[0037] See Figure 1 , a first aspect of this application provides a separator 1 for a sodium-ion battery. The separator 1 includes a separator substrate 10, a first functional layer 20 and a second functional layer 30. The first functional layer 20 is disposed on one side of the separator substrate 10 close to the negative electrode of the sodium-ion battery. The first functional layer 20 includes a first gas adsorption layer 21 and a first water absorption layer 22 which are sequentially stacked on the separator substrate 10. The second functional layer 30 is disposed on one side of the separator substrate 10 close to the positive electrode of the sodium-ion battery. The second functional layer 30 includes a second water absorption layer 31, a sodium supplementation layer 32 and a second gas adsorption layer 33 which are sequentially stacked on the separator substrate 10.

[0038] The separator 1 provided by this application has a first functional layer 20 disposed on the negative electrode side of the sodium-ion battery, and a second functional layer 30 disposed on the positive electrode side of the sodium-ion battery. On the one hand, the applicant has found that in actual production, the moisture content of the negative electrode sheet is higher than that of the positive electrode sheet. Therefore, the first water-absorbing layer 22 is disposed at a position away from the separator substrate 10 and close to the negative electrode, and the second water-absorbing layer 31 is disposed at a position close to the separator substrate 10 and away from the positive electrode, thereby slowing down the damage of water molecules in the battery to the positive electrode material and ensuring the structural stability and electrochemical performance of the positive electrode material. On the other hand, the sodium-supplementing layer 32 in the second functional layer 30 provides an additional sodium source, improving the energy density and first Coulomb efficiency of the sodium-ion battery. The first gas adsorption layer 21 is disposed at a position close to the separator substrate 10 and away from the negative electrode, and the second gas adsorption layer 33 is disposed between the sodium-supplementing layer 32 and the positive electrode. It can not only adsorb the gas generated during the cycling of the battery together with the first gas adsorption layer 21, but also in-situ adsorb the gas released during the sodium-supplementing process of the sodium-supplementing layer 32, slowing down the damage of the gas to the battery interface and improving the cycle life of the battery.

[0039] In summary, the separator 1 provided by this application, by setting the sodium-supplementing layer 32, the first gas adsorption layer 21, the second gas adsorption layer 33, the first water-absorbing layer 22 and the second water-absorbing layer 31 and reasonably configuring the positions of the above layer structures, improves the energy density, first Coulomb efficiency, structural stability and cycle life of the sodium-ion battery.

[0040] In some of the embodiments, the thickness ratio of the first gas adsorption layer 21 to the second gas adsorption layer 33 is 1:(1~1.5), including but not limited to 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5.

[0041] It can be understood that a certain amount of gas is released during the cycling of the sodium-ion battery, and a part of the gas is also generated by the sodium-supplementing agent in the sodium-supplementing layer 32 of the second functional layer 30 during the sodium-supplementing process. By setting the thickness of the second gas adsorption layer 33 slightly higher than that of the first gas adsorption layer 21, it can be realized that while the second gas adsorption layer 33 adsorbs the gas generated during the cycling of the battery, it can also in-situ adsorb the gas generated by the sodium-supplementing layer 32, improving the gas adsorption efficiency, slowing down the damage of the gas to the battery interface, and improving the cycle life of the battery.

[0042] In some of the embodiments, the thickness of the first gas adsorption layer 21 is 0.3μm~5μm, including but not limited to 0.3μm, 0.5μm, 1μm, 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 4.5μm, 5μm.

[0043] By setting the thickness of the first gas adsorption layer 21 to be 0.3 μm to 5 μm, the present application can improve the gas adsorption efficiency, slow down the damage of the gas to the battery interface, increase the cycle life of the battery, while maintaining the air permeability of the separator 1, reducing the internal resistance of the battery, and balancing the structural stability and electrochemical performance of the battery.

[0044] In some embodiments, the thickness ratio of the first water absorption layer 22 to the second water absorption layer 31 is (1 to 1.5):1, including but not limited to, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1.

[0045] It can be understood that in actual production, the water content of the negative electrode sheet is higher than that of the positive electrode sheet. By setting the thickness of the first water absorption layer 22 to be slightly higher than that of the second water absorption layer 31, the first water absorption layer 22 and the second water absorption layer 31 can both effectively adsorb the water generated in the positive and negative electrode sheets of the battery during the cycling process, which is beneficial to slowing down the damage of water molecules in the battery to the positive electrode material and ensuring the structural stability and electrochemical performance of the positive electrode material.

[0046] In some embodiments, the thickness of the second water absorption layer 31 is 0.1 μm to 2 μm, including but not limited to 0.1 μm, 0.5 μm, 1 μm, 1.5 μm, 2 μm.

[0047] By setting the thickness of the second water absorption layer 31 to be 0.1 μm to 2 μm, the present application can improve the water adsorption capacity of the separator 1, reduce the damage of the internal water of the battery to the positive electrode material, while maintaining the air permeability of the separator 1, reducing the internal resistance of the battery, and balancing the structural stability and electrochemical performance of the battery.

[0048] In some embodiments, the thickness of the sodium supplementation layer 32 is 0.1 μm to 3 μm, including but not limited to 0.1 μm, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm.

[0049] By setting the thickness of the sodium supplementation layer 32 to be 0.1 μm to 3 μm in the present application, an appropriate amount of sodium source can be provided, increasing the energy density and the first Coulombic efficiency of the battery, while avoiding the excessive release of gas by the too thick sodium supplementation layer 32 and increasing the internal resistance of the battery, ensuring the safety and cycle life of the battery.

[0050] In some embodiments, the sodium supplementation layer 32 has an intermittent coating structure, and the intermittent coating structure includes a coating area and a gap area, and the width of the gap area is 1 / 5 to 1 / 4 of the width of the coating area.

[0051] This application uses a sodium replenishing layer 32 with an intermittent coating structure, where the width of the gap region is 1 / 5 to 1 / 4 of the width of the coating region, thereby improving the sodium replenishing efficiency and gas adsorption effect of the sodium replenishing layer 32. The gap region can serve as a gas release channel, which helps to release gas more evenly during the sodium replenishing process, reduces the damage of gas to the battery interface, and improves the cycle life of the battery. In addition, intermittent coating can also reduce the use of materials and lower costs.

[0052] In some specific embodiments, the coating width of the coating region is 100 mm, and the width of the gap region is 20 mm to 25 mm.

[0053] In some of these embodiments, the first gas adsorption layer 21 and the second gas adsorption layer 33 are metal-organic framework layers.

[0054] The first gas adsorption layer 21 and the second gas adsorption layer 33 of this application are metal-organic framework layers. The metal-organic framework layer has a pore structure and a high specific surface area, thereby enhancing the adsorption capacity for gas molecules, effectively reducing the gas accumulation inside the battery, and improving the cycle performance of the battery.

[0055] It should be noted that the main material of the metal-organic framework layer is a metal-organic framework compound, and the metal-organic framework compound is selected from any one of ZIF-67, ZIF-8, MOF-74, MOF-5, MOF-11, MIL-53, MIL-100, and MIL-101. These materials are all conventional gas adsorbent materials in the prior art, and this application has not made any improvements to them; the above metal-organic framework layer also includes a binder, and the binder is selected from any one of polytetrafluoroethylene, polyvinylidene fluoride, acrylic acid, polyethylene oxide, sodium carboxymethyl cellulose, styrene-butadiene rubber, hydroxypropyl methylcellulose, carboxylated styrene-butadiene latex, and polyvinyl alcohol. These materials are all conventional binder materials in the prior art, and this application has not made any improvements to them.

[0056] In some of these embodiments, the first water absorption layer 22 and the second water absorption layer 31 are the same or different, and are independently selected from any one of a calcium chloride layer, an aluminum chloride layer, a magnesium sulfate layer, and an activated carbon layer.

[0057] It should be noted that the main materials of the calcium chloride layer, the aluminum chloride layer, the magnesium sulfate layer, and the activated carbon layer are calcium chloride, aluminum chloride, magnesium sulfate, and activated carbon respectively. These materials are all conventional water-absorbing materials in the prior art, and this application has not made any improvements to them; the first water absorption layer 22 and the second water absorption layer 31 also include a binder, and the binder is selected from any one of polytetrafluoroethylene, polyvinylidene fluoride, acrylic acid, polyethylene oxide, sodium carboxymethyl cellulose, styrene-butadiene rubber, hydroxypropyl methylcellulose, carboxylated styrene-butadiene latex, and polyvinyl alcohol. These materials are all conventional binder materials in the prior art, and this application has not made any improvements to them.

[0058] In some of these embodiments, the sodium supplement layer 32 is selected from any one of a sodium azide layer, a sodium carbonate layer, a sodium nitrite layer, a sodium oxide layer, a sodium peroxide layer, a sodium oxalate layer, a squaric acid sodium layer, a tetrasodium ethylenediaminetetraacetate layer, and a pentasodium diethylenetriaminepentaacetate layer.

[0059] It should be noted that the main materials of the sodium azide layer, the sodium carbonate layer, the sodium nitrite layer, the sodium oxide layer, the sodium peroxide layer, the sodium oxalate layer, the squaric acid sodium layer, the tetrasodium ethylenediaminetetraacetate layer, and the pentasodium diethylenetriaminepentaacetate layer are sodium azide, sodium carbonate, sodium nitrite, sodium oxide, sodium peroxide, sodium oxalate, squaric acid sodium, tetrasodium ethylenediaminetetraacetate, and pentasodium diethylenetriaminepentaacetate respectively. These materials are all conventional sodium supplement agent materials in the prior art, and this application has not made any improvements thereto; the sodium supplement layer 32 further includes a binder and a conductive agent. The binder is selected from any one of polytetrafluoroethylene, polyvinylidene fluoride, acrylic acid, polyethylene oxide, sodium carboxymethyl cellulose, styrene-butadiene rubber, hydroxypropyl methylcellulose, carboxy styrene-butadiene latex, and polyvinyl alcohol. These materials are all conventional binder materials in the prior art, and this application has not made any improvements thereto; the conductive agent is selected from any one of carbon nanotubes, conductive carbon black, and graphene. These materials are all conventional conductive agent materials in the prior art, and this application has not made any improvements thereto.

[0060] In some of these embodiments, the separator substrate 10 can be a non-woven fabric, a film, or a composite film having a porous structure.

[0061] In some of these embodiments, the material of the separator substrate 10 is selected from any one of polyethylene, polypropylene, and a composite material of polyethylene and polypropylene.

[0062] It should be noted that polyethylene, polypropylene, and the composite material of polyethylene and polypropylene are all conventional separator substrate materials in the prior art, and this application has not made any improvements thereto.

[0063] In some of these embodiments, the thickness of the separator substrate 10 is 5 μm to 30 μm, including but not limited to 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, and 30 μm.

[0064] The second aspect of this application provides a sodium-ion battery, which includes a positive electrode, a negative electrode, and the separator provided in the first aspect above. The positive electrode is a layered oxide positive electrode.

[0065] The sodium-ion battery provided by this application includes the separator 1 provided in the first aspect above. By providing the sodium supplement layer 32, the first gas adsorption layer 21, the second gas adsorption layer 33, the first water absorption layer 22, and the second water absorption layer 31 and reasonably configuring the positions of the above-mentioned layered structures, the energy density, the initial Coulomb efficiency, the structural stability, and the cycle life of the sodium-ion battery are improved.

[0066] It is understandable that there are problems such as interface instability and poor air stability in the layered oxide cathode during charge and discharge. It will undergo a hydration reaction with water molecules to form a hydrated phase, affecting the structural stability and electrochemical performance of the material. Therefore, the separator in this application is particularly suitable for sodium-ion batteries with a layered oxide cathode.

[0067] In some of these embodiments, the layered oxide cathode includes any one of the compounds represented by the following general formula: Na i MO2, where 0 < i ≤ 1, and M is selected from any one of V, Cr, Mn, Fe, Co, Ni, Cu; further, the layered oxide cathode includes Na[Cu 1 / 9 Ni 2 / 9 Fe 1 / 3 Mn 1 / 3 O2, Na 0.44 MnO2, Na 2 / 3 [Fe 1 / 2 Mn 1 / 2 O2, Na[Ni 1 / 3 Fe 1 / 3 Mn 1 / 3 O2, Na 7 / 9 [Cu 2 / 9 Fe 1 / 9 Mn 2 / 3 O2, and NaNi 0.7 Co 0.15 Mn 0.15 O2.

[0068] In some of these embodiments, the negative electrode is any one of a hard carbon negative electrode, a soft carbon negative electrode, or a graphite negative electrode.

[0069] The third aspect of this application provides an electrical device, and this electrical device includes the sodium-ion battery provided in the second aspect above. Thus, this electrical device has all the features and advantages of the sodium-ion battery provided in the second aspect above, which will not be elaborated here.

[0070] The electrical device of this application is not particularly limited, and it can be any electrical device known in the prior art. For example, the electrical device can include but is not limited to laptop computers, pen input computers, mobile computers, e-book players, portable phones, portable fax machines, portable copiers, portable printers, head-mounted stereo headphones, video recorders, LCD TVs, hand-held cleaners, portable CD players, mini-discs, transceivers, electronic notepads, calculators, memory cards, portable recorders, radios, backup power supplies, motors, cars, motorcycles, motorized bicycles, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries, and sodium-ion capacitors.

[0071] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0072] The above-described embodiments only express several implementation manners of the present application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the patent of the present application. It should be noted that for those of ordinary skill in the art, without departing from the technical concept of the present application, several deformations and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the appended claims.

Claims

1. A separator, characterized in that, For a sodium-ion battery, comprising: A separator substrate (10); A first functional layer (20), disposed on one side of the separator substrate (10) close to the negative electrode of the sodium-ion battery, the first functional layer (20) comprising a first gas adsorption layer (21) and a first water absorption layer (22) sequentially stacked on the separator substrate (10); A second functional layer (30), disposed on one side of the separator substrate (10) close to the positive electrode of the sodium-ion battery, the second functional layer (30) comprising a second water absorption layer (31), a sodium supplement layer (32) and a second gas adsorption layer (33) sequentially stacked on the separator substrate (10).

2. The diaphragm according to claim 1, wherein The thickness ratio of the first gas adsorption layer (21) to the second gas adsorption layer (33) is 1:(1 - 1.5).

3. The diaphragm according to claim 2, characterized in that, The thickness of the first gas adsorption layer (21) is 0.3 μm - 5 μm.

4. The diaphragm according to claim 1, characterized in that, The thickness ratio of the first water absorption layer (22) to the second water absorption layer (31) is (1 - 1.5):

1.

5. The separator according to claim 4, characterized in that, The thickness of the second water absorption layer (31) is 0.1 μm - 2 μm.

6. The separator according to any one of claims 1 to 5, characterized in that, The thickness of the sodium supplement layer (32) is 0.1 μm - 3 μm.

7. The separator according to any one of claims 1 to 5, characterized in that, The sodium supplement layer (32) is a discontinuous coating structure, the discontinuous coating structure comprising a coating area and a gap area, and the width of the gap area is 1 / 5 - 1 / 4 of the width of the coating area.

8. The separator according to any one of claims 1 to 5, characterized in that, The first gas adsorption layer (21) and the second gas adsorption layer (33) are metal-organic framework layers; and / or, The first water absorption layer (22) and the second water absorption layer (31) are the same or different, and are independently selected from any one of a calcium chloride layer, an aluminum chloride layer, a magnesium sulfate layer and an activated carbon layer; and / or, The sodium supplement layer (32) is selected from any one of a sodium azide layer, a sodium carbonate layer, a sodium nitrite layer, a sodium oxide layer, a sodium peroxide layer, a sodium oxalate layer, a sodium squarate layer, a sodium ethylenediaminetetraacetate layer and a sodium diethylenetriaminepentaacetate layer.

9. A sodium-ion battery, characterized in that, Comprising a positive electrode, a negative electrode and a separator as described in any one of claims 1 - 8, and the positive electrode is a layered oxide positive electrode.

10. An electrical device, characterized in that, Comprising a sodium-ion battery as described in claim 9.

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