Diaphragm, preparation method thereof, preparation process of battery, battery and electric device

Abstract

The present application relates to the technical field of battery, in particular to a kind of diaphragm and preparation method thereof, the preparation process of battery, battery and electric device.The diaphragm of the present application includes sodium supplementing compound, the chemical formula of sodium supplementing compound is at least one of NaAlO2, Na2M n O 2n+1 Wherein M includes at least one of Ti, Zr, Si, and 1≤n≤10.The above-mentioned sodium supplementing compound in the present application can be decomposed to obtain sodium ion and inorganic material during formation or charging process, the product sodium ion can supplement the sodium ion consumed during formation or charging process, and the product inorganic material can improve the high-temperature shrinkage and puncture resistance of diaphragm, effectively improve the cycle performance of battery.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a separator and its preparation method, a battery manufacturing process, a battery, and an electrical device. Background Technology

[0002] Compared to lithium-ion batteries, which use scarce elements such as lithium, cobalt, and nickel, sodium-ion batteries have the advantage of abundant sodium resources and low raw material costs, making them highly promising for the energy storage field.

[0003] Due to irreversible reactions such as the formation of the solid electrolyte interphase (SEI) film on the negative electrode surface during the initial charge-discharge formation process, sodium ions are lost from the positive electrode material, leading to a decrease in the energy density of sodium-ion batteries. Therefore, developing sodium replenishment materials and methods that meet the requirements is urgently needed. Summary of the Invention

[0004] The main objective of this invention is to provide a separator designed to improve the performance of sodium secondary batteries.

[0005] To achieve the above objectives, the present invention provides a diaphragm comprising a sodium-supplementing compound, wherein the chemical formula of the sodium-supplementing compound is NaAlO2 or Na2M. n O 2n+1 At least one of the following, wherein M includes at least one of Ti, Zr, and Si, and 1 ≤ n ≤ 10.

[0006] The sodium-replenishing compound described in this application can decompose into sodium ions and inorganic materials during the formation or charging process. The sodium ions produced can replenish the sodium ions consumed during the formation or charging process, while the inorganic materials produced can improve the high-temperature shrinkage and puncture resistance of the separator, effectively improving the cycle performance of the battery.

[0007] Optionally, 1 ≤ n ≤ 5.

[0008] Sodium supplement compound Na2M n O 2n+1 In this context, 1≤n≤5, sodium-supplementing compounds with n in the above range are relatively common in nature, easy to obtain, and have low cost.

[0009] Optionally, the Na2M n O 2n+1 Including Na2TiO3, Na2Ti2O5, and Na2Ti5O 11 Na2Ti6O 13 , Na2ZrO3, Na2SiO3, Na2Si2O5, Na2Si3O7, Na2Si5O 11 Na2Si 10 O 21At least one of them.

[0010] Na2M in this application n O 2n+1 Including but not limited to Na2TiO3, Na2Ti6O 13 Na2Ti5O 11 , Na2ZrO3, Na2SiO3, Na2Si2O5, Na2Si3O7, Na2Si5O 11 Na2Si 10 O 21 At least one of them. It is understood that sodium-supplementing compounds can be oxidized and decomposed during formation or charging to yield sodium ions and inorganic materials.

[0011] For example, 4NaAlO2-4e-→2Al2O3+4Na + +O2;

[0012] Alternatively, 2Na₂TiO₃-4e⁻→2TiO₂+4Na + +O2;

[0013] Alternatively, 2Na2Ti6O 13 -4e- → 12TiO2 + 4Na + +O2;

[0014] Alternatively, 2Na₂ZrO₃-4e⁻→2ZrO₂+4Na + +O2;

[0015] Alternatively, 2Na2SiO3-4e-→2SiO2+4Na + +O2;

[0016] Alternatively, 2Na2Si2O5-4e-→4SiO2+4Na + +O2;

[0017] Alternatively, 2Na2Si3O7-4e-→6SiO2+4Na + +O2;

[0018] Alternatively, 2Na2Si 10 O 21 -4e- → 20SiO2 + 4Na + +O2. That is, sodium-containing compounds can be oxidized and decomposed during formation or charging to yield sodium ions and inorganic materials.

[0019] The inorganic materials obtained from the decomposition have high hardness and high temperature resistance, which can improve the high temperature shrinkage performance of the diaphragm and reduce the problem of dendrite puncture of the diaphragm.

[0020] Optionally, the membrane includes a sodium-supplementing membrane, the sodium-supplementing membrane includes the sodium-supplementing compound, and the thickness of the sodium-supplementing membrane ranges from 5 μm to 15 μm; preferably, from 7 μm to 13 μm.

[0021] Alternatively, the diaphragm includes a base membrane and a sodium supplement layer disposed on the base membrane, the sodium supplement layer including the sodium supplement compound, and the thickness of the sodium supplement layer ranging from 5 μm to 15 μm; preferably, from 7 μm to 13 μm.

[0022] It is understood that the diaphragm in this application can be a single-layer diaphragm or a multi-layer diaphragm. When it is a single-layer diaphragm, the single-layer diaphragm is a sodium-supplementing diaphragm. For example, the sodium-supplementing diaphragm raw material (sodium-supplementing compound, polymer) is melt-extruded to obtain the sodium-supplementing diaphragm by melt extrusion. When it is a multi-layer diaphragm, at least one layer of the multi-layer diaphragm is a sodium-supplementing diaphragm. For example, the sodium-supplementing diaphragm raw material (sodium-supplementing compound, polymer) and the base film raw material (polymer) are melt-extruded simultaneously by melt co-extrusion. The resulting diaphragm includes a sodium-supplementing diaphragm composed of a polymer-coated sodium-supplementing compound and a base film bonded to the sodium-supplementing diaphragm, forming a double-layer diaphragm. The sodium-supplementing diaphragm includes a sodium-supplementing compound, and the thickness of the sodium-supplementing diaphragm ranges from 5 μm to 15 μm; preferably, from 7 μm to 13 μm. It is understood that the thickness of the sodium-supplementing diaphragm mentioned above refers to the thickness after hot pressing.

[0023] It is also understood that the separator includes a base membrane and a sodium-supplementing layer disposed on the base membrane. The sodium-supplementing layer includes a sodium-supplementing compound, and the thickness of the sodium-supplementing layer ranges from 5 μm to 15 μm; preferably, 7 μm to 13 μm. That is, the separator can be obtained by preparing the sodium-supplementing compound into a slurry and coating it onto the base membrane, with the thickness of the sodium-supplementing layer ranging from 5 μm to 15 μm; preferably, 7 μm to 13 μm.

[0024] When the thickness of the sodium-replenishing diaphragm or sodium-replenishing layer is within the above range, it can improve the sodium-replenishing capacity of the diaphragm, as well as the diaphragm's high-temperature resistance and puncture resistance.

[0025] Optionally, the Dv50 value of the sodium supplement compound ranges from 100 nm to 3 μm, preferably from 100 nm to 1 μm.

[0026] When the Dv50 of the sodium-supplementing compound is within the above range, it can help decompose the sodium-supplementing compound. In addition, it can alleviate the problem that excessively large particles of sodium-supplementing compounds can clog the micropores of the sodium-supplementing membrane, improve the problem that excessively small particles of sodium-supplementing compounds are prone to agglomeration, and facilitate the preparation of sodium-supplementing membranes of appropriate thickness.

[0027] Optionally, the membrane includes a sodium-supplementing membrane, which further includes a polymer coated on the surface of the sodium-supplementing compound.

[0028] The sodium-replenishing membrane also includes a polymer. The surface of the sodium-replenishing compound is coated with a polymer. By coating the sodium-replenishing compound with the polymer, the sodium-replenishing compound in the sodium-replenishing membrane is less likely to fall off the membrane, thus improving the sodium replenishment effect of the membrane in sodium secondary batteries.

[0029] Meanwhile, considering that sodium-supplemented compounds will oxidize and decompose into inorganic materials during formation or charging, polymer coating also reduces the problem of inorganic materials being released into the electrolyte.

[0030] Optionally, the sodium-supplemented diaphragm further includes a toughening agent;

[0031] Alternatively, the sodium-supplementing membrane may further include a toughening agent, wherein the toughening agent accounts for 5% to 15% of the mass of the sodium-supplementing membrane, preferably 5% to 10%.

[0032] To improve the bonding strength between the sodium-supplementing compound and the polymer, the sodium-supplementing membrane also includes a toughening agent. Furthermore, the toughening agent accounts for 5% to 15% of the mass of the sodium-supplementing membrane, preferably 5% to 10%.

[0033] Optionally, the sodium-supplementing membrane further includes a polymer, the polymer including at least one of polyethylene, polypropylene, polyethylene terephthalate, polyamide, and polyimide;

[0034] And / or, the sodium-supplemented diaphragm further includes a toughening agent, the toughening agent being at least one selected from polytetrafluoroethylene, polyvinylidene fluoride, acrylic acid, polyethylene oxide, sodium carboxymethyl cellulose, styrene-butadiene rubber, hydroxypropyl methyl cellulose, carboxylated styrene-butadiene latex, or polyvinyl alcohol.

[0035] The sodium-supplementing diaphragm in this application also includes polymers, including but not limited to at least one of polyethylene, polypropylene, polyethylene terephthalate, polyamide, and polyimide.

[0036] The sodium-supplemented diaphragm in this application also includes a toughening agent, which includes, but is not limited to, at least one of polytetrafluoroethylene, polyvinylidene fluoride, acrylic acid, polyethylene oxide, sodium carboxymethyl cellulose, styrene-butadiene rubber, hydroxypropyl methylcellulose, carboxylated styrene-butadiene latex, or polyvinyl alcohol.

[0037] Optionally, the diaphragm further includes a non-sodium-supplemented diaphragm, wherein the sodium-supplemented diaphragm is disposed on at least one side of the non-sodium-supplemented diaphragm.

[0038] It is understood that the diaphragm also includes a non-sodium-supplemented diaphragm, that is, the diaphragm includes at least two layers, at least one of which is a non-sodium-supplemented diaphragm and at least one of which is a sodium-supplemented diaphragm, with the sodium-supplemented diaphragm located on at least one side of the non-sodium-supplemented diaphragm.

[0039] By using a multi-layered membrane, the membrane thickness can be adjusted, and the porosity of the non-sodium-supplemented membrane can be adjusted as needed. For example, the porosities of the sodium-supplemented membrane and the non-sodium-supplemented membrane can be set differently. In one embodiment, the porosity of the non-sodium-supplemented membrane is greater than that of the sodium-supplemented membrane to reduce the shedding of inorganic materials from the sodium-supplemented membrane into the electrolyte and to improve the overall permeability of the membrane, thereby enhancing the ion passage performance. For example, in one embodiment, the non-sodium-supplemented membrane can be a base membrane, and the prepared sodium-supplemented membrane can be adhered to the surface of the base membrane to form a membrane with at least two layers.

[0040] Optionally, the diaphragm is disposed on one side of the positive electrode or the negative electrode, and the sodium-supplementing diaphragm is disposed on the side of the non-sodium-supplementing diaphragm facing the positive electrode.

[0041] In theory, the sodium-supplementing membrane can be placed on either side of the non-sodium-supplementing membrane. Considering that the sodium-supplementing compound will undergo an oxidative decomposition reaction during formation or charging, the potential of the positive electrode is higher than that of the negative electrode, which is more conducive to the decomposition of the sodium-supplementing compound. Therefore, in the preferred case, the sodium-supplementing membrane is placed on the side of the non-sodium-supplementing membrane facing the positive electrode.

[0042] Optionally, the total thickness of the diaphragm ranges from 13 μm to 30 μm; preferably, it ranges from 15 μm to 20 μm.

[0043] It is understood that the diaphragm in this application may be a multilayer diaphragm. When it is a multilayer diaphragm, at least one of the multilayer diaphragms is a sodium-supplementing diaphragm. The total thickness of the diaphragm in the multilayer diaphragm ranges from 13 μm to 30 μm; preferably, it is from 15 μm to 20 μm.

[0044] For example, a multilayer membrane includes a base membrane and a sodium-supplementing membrane disposed on at least one side of the base membrane. By placing the sodium-supplementing membrane on the base membrane, the overall thickness of the membrane can be increased. At the same time, the porosity of the base membrane can be greater than that of the sodium-supplementing membrane, thereby improving the overall puncture resistance and air permeability of the membrane.

[0045] The base membrane includes organic microporous membranes, and the materials of the base membrane include organic polymer materials, such as polyethylene, polypropylene, etc.

[0046] The base film is made of the same material as the polymer.

[0047] In theory, the material of the base membrane and the polymer can be the same or different, but it is preferred that they are the same to mitigate the problem of inconsistent ion conduction rates between the base membrane and the sodium-supplementing separator, which affects battery performance. For example, the base membrane material includes at least one of polyethylene, polypropylene, polyethylene terephthalate, polyamide, and polyimide.

[0048] Optionally, the mass percentage of the sodium-supplementing compound is 5% to 30% of the total mass of the diaphragm, preferably 10% to 20%.

[0049] It is understood that when the diaphragm is a single-layer diaphragm, the mass percentage of the sodium supplement compound is 5% to 30% of the mass of the single-layer diaphragm, preferably 10% to 20%.

[0050] When the diaphragm is a multilayer diaphragm, at least one layer is a sodium-supplementing diaphragm, and the mass percentage of the sodium-supplementing compound is 5% to 30% of the mass of the multilayer diaphragm, preferably 10% to 20%.

[0051] In other words, by setting the mass percentage of the sodium-replenishing compound relative to the mass of the membrane within the aforementioned range, the sodium ions lost during formation or charging can be replenished. It is understood that, for example, when the mass percentage of the sodium-replenishing compound relative to the mass of the membrane is greater than 8%, the sodium-replenishing compound will not be completely decomposed during the formation stage, and there will be a remaining sodium-replenishing compound used to decompose during the cycling process to replenish the sodium loss during the cycling process.

[0052] Furthermore, by setting the mass percentage of the sodium-supplementing compound within the aforementioned range, the inorganic materials generated from the decomposition of the sodium-supplementing compound can improve the high-temperature shrinkage and puncture resistance of the separator, effectively enhancing the battery's cycle performance. It is understood that setting the mass percentage of the sodium-supplementing compound within the aforementioned range can improve the sodium-supplementing effect and improve the battery's mass energy density. Taking all factors into consideration, this application uses a sodium-supplementing compound mass percentage of 5% to 30% of the total separator mass, preferably 10% to 20%.

[0053] Optionally, the porosity of the diaphragm ranges from 30% to 45%, preferably from 35% to 45%.

[0054] Considering the inorganic materials generated by sodium addition and decomposition, the porosity of the diaphragm is set between 30% and 45% to reduce the amount of inorganic materials falling into the electrolyte.

[0055] Optionally, the membrane includes a sodium-supplemented membrane and a non-sodium-supplemented membrane, wherein the sodium-supplemented membrane is disposed on at least one side of the non-sodium-supplemented membrane, and the porosity of the sodium-supplemented membrane is less than or equal to the porosity of the non-sodium-supplemented membrane; preferably, the difference between the porosity of the non-sodium-supplemented membrane and the porosity of the sodium-supplemented membrane is less than or equal to 5%.

[0056] The porosity of the sodium-supplemented membrane and the non-sodium-supplemented membrane can be set to be the same or different. For example, in one embodiment, the porosity of the non-sodium-supplemented membrane is greater than that of the sodium-supplemented membrane to reduce the shedding of inorganic materials from the sodium-supplemented membrane into the electrolyte and to improve the overall permeability of the membrane, thereby enhancing the ion passage performance. When the porosities of the two membranes are different, and the porosity of the sodium-supplemented membrane is less than that of the non-sodium-supplemented membrane, the difference between the porosities of the two membranes is less than or equal to 5%.

[0057] Optionally, the porosity of the sodium-supplementing membrane ranges from 30% to 45%, preferably from 35% to 45%.

[0058] And / or, the porosity of the non-sodium-supplemented diaphragm ranges from 30% to 45%, preferably from 37% to 45%.

[0059] Setting the porosity of the sodium-supplemented membrane within the above-mentioned range can reduce the shedding of inorganic materials from the membrane into the electrolyte.

[0060] The porosity of the non-sodium-supplemented diaphragm is set within the above range to improve the overall air permeability of the diaphragm and enhance the ion passage performance.

[0061] Optionally, this application also provides a method for preparing the diaphragm as described above, comprising:

[0062] The raw materials for preparing the diaphragm include sodium-supplementing compounds with the chemical formulas NaAlO2 and Na2M. n O 2n+1 At least one of the following, wherein M includes at least one of Ti, Zr, and Si, and 1 ≤ n ≤ 10;

[0063] The raw materials for the diaphragm are prepared into a diaphragm.

[0064] Understandably, in one embodiment, the diaphragm can be a single-layer membrane, which can be produced using melt extrusion technology, with the polymer coating the surface of the sodium-supplementing compound. That is, the raw materials for the diaphragm (sodium-supplementing compound, polymer) are added to the extruder of the diaphragm extrusion apparatus for melt extrusion, and a composite membrane substrate is obtained through a cooling roller; the composite membrane substrate is then subjected to a cold drawing process to form holes, followed by heat treatment and a hot drawing process to form holes, and finally shaped to obtain a single-layer membrane.

[0065] In another embodiment, the diaphragm includes a base membrane and a sodium supplement layer disposed on the base membrane. In the raw material preparation step of the diaphragm, the sodium supplement compound can be prepared into a slurry and coated on the base membrane to obtain the diaphragm.

[0066] Alternatively, in another embodiment, the diaphragm can be a multilayer membrane, with a single-layer membrane produced by melt extrusion technology and then bonded to a base membrane to form a double-layer structure.

[0067] Alternatively, in another embodiment, a melt co-extrusion method is used, in which the diaphragm material (sodium supplement compound, polymer) and the base film material (polymer) are melt co-extruded simultaneously. The resulting diaphragm includes a membrane structure composed of a polymer-coated sodium supplement compound and a base film bonded to the membrane structure. Melt co-extrusion refers to an extrusion process in which several extruders simultaneously supply different plastic molten material flows to a composite die head and merge them into a multi-layer composite product.

[0068] Optionally, the process of preparing the membrane from the raw materials includes:

[0069] The raw material for the diaphragm is added to the extruder of the diaphragm extrusion device for melt extrusion, and a composite membrane substrate is obtained by passing it through a cooling roller;

[0070] The composite membrane substrate is subjected to a cold drawing process to form holes, followed by a heat treatment and hot drawing process to form holes, and then shaped to obtain a sodium-supplemented diaphragm.

[0071] An extrusion diaphragm device is used to push diaphragm raw material and extrude it into a film.

[0072] The sodium-supplemented separator prepared by melt extrusion includes a polymer-coated sodium-supplemented compound. This can alleviate the problem of inorganic materials generated by the decomposition of the sodium-supplemented compound falling off the separator into the electrolyte. It can also alleviate the problem of sodium-supplemented compound falling off the separator due to insufficient adhesion when it is coated on the separator during folding and rolling of the battery assembly, which would reduce the sodium-supplementation efficiency. Furthermore, this preparation method does not involve the use of organic solvents, which reduces production costs and environmental pollution.

[0073] Optionally, the step of preparing the raw materials for the diaphragm further includes:

[0074] The sodium-supplementing compound, polymer, and toughening agent are stirred and mixed at a stirring speed of 400 r / min to 800 r / min for 0.5 h to 1 h to obtain the raw material for the diaphragm.

[0075] In the preparation of the raw materials for the diaphragm, the sodium-supplementing compound, polymer, and toughening agent are stirred and mixed at a speed of 400 r / min to 800 r / min for 0.5 h to 1 h to obtain the raw materials for the diaphragm. Adding the toughening agent can improve the bonding strength between the sodium-supplementing material and the polymer, as well as the tightness of the bonding between the sodium-supplemented diaphragm and the base membrane.

[0076] Optionally, the temperature of the cooling roller is 15°C to 30°C;

[0077] And / or, the thickness of the composite film substrate is 10 μm to 25 μm;

[0078] And / or, the cold drawing process is performed under the conditions of uniaxial stretching at a temperature of 15°C to 30°C and a stretching speed of 0.01 m / min to 0.1 m / min;

[0079] And / or, the heat treatment conditions are heating at 15°C to 30°C below the polymer melting point for 30 to 60 minutes;

[0080] And / or, the hot-drawing process is performed under the following conditions: uniaxial stretching at a temperature of 100°C to 160°C, a stretching ratio of 1 to 5 times, and a stretching speed of 0.05 m / min to 0.5 m / min.

[0081] And / or, the shaping treatment conditions are: temperature 15°C to 30°C, time 0.5h to 2h.

[0082] During the preparation of the diaphragm, the corresponding steps are made to meet the above conditions to obtain a diaphragm of appropriate thickness.

[0083] Optionally, this application also provides a battery manufacturing process, the battery manufacturing process including assembling a separator, a positive electrode, and a negative electrode, wherein the separator includes the separator as described above;

[0084] Alternatively, the battery manufacturing process includes assembling a separator, a positive electrode, and a negative electrode, wherein the separator includes a separator prepared by the method described above.

[0085] Optionally, the assembly of the separator, positive electrode, and negative electrode includes:

[0086] The battery, after being encapsulated with the separator, positive electrode, and negative electrode, is injected with electrolyte and then subjected to formation treatment.

[0087] Formation, in sodium battery formation, is the first charging process of a sodium battery after electrolyte injection. This process activates the active materials in the battery, thus activating the sodium battery.

[0088] Considering that the sodium-supplementing compound in this application can decompose into sodium ions and inorganic materials during the formation process, the battery after being packaged with the separator, positive electrode, and negative electrode is injected with electrolyte and subjected to formation treatment. This allows the sodium-supplementing compound in the separator to decompose, and the resulting sodium ions can replenish the sodium ions consumed during formation or charging. The resulting inorganic materials can improve the high-temperature shrinkage and puncture resistance of the separator, effectively improving the cycle performance of the battery.

[0089] Optionally, in the step of forming the battery, the voltage range of the forming is 3V to 4.2V;

[0090] And / or, the temperature of the formation is 45°C to 80°C;

[0091] And / or, the formation time is 2 hours to 5 hours;

[0092] And / or, the vacuum degree of the formed battery ranges from 0.01 MPa to 0.1 MPa.

[0093] Using the voltage range mentioned above during the formation process helps to decompose sodium-containing compounds.

[0094] Within the aforementioned formation temperature range, the decomposition rate of sodium-supplemented compounds can be increased.

[0095] Within the aforementioned formation time range, sodium ions lost during the formation stage can be effectively replenished.

[0096] The aforementioned vacuum level inside the battery during the formation process can eliminate the gases generated during the decomposition of sodium compounds.

[0097] In addition, setting the battery vacuum level to the aforementioned level can reduce electrolyte loss and mitigate the problem of inorganic materials generated during the decomposition of sodium compounds being carried into the electrolyte from the polymer pores.

[0098] Optionally, after the formation process of the battery, the battery is further charged with a voltage range of 3V to 4.2V.

[0099] Considering that the sodium-supplementing compound in this application can decompose into sodium ions and inorganic materials during charging, setting the charging voltage range within the above-mentioned range can help decompose the sodium-supplementing compound.

[0100] In other words, the sodium-replenishing compound of this application not only decomposes during the formation stage to help replenish sodium ions during the formation stage, but also decomposes during the battery charging process to replenish sodium ions during the cycle.

[0101] This application also provides a battery comprising a battery prepared by the battery preparation process described above.

[0102] This application also provides an electrical device, which includes the battery as described above.

[0103] The diaphragm of this application includes a sodium-supplementing compound, the chemical formula of which is NaAlO2 or Na2M. n O 2n+1At least one of the following, wherein M includes at least one of Ti, Zr, and Si, and 1 ≤ n ≤ 10. The sodium-replenishing compound described above in this application can decompose to obtain sodium ions and inorganic materials during the formation or charging process. The sodium ions produced can replenish the sodium ions consumed during the formation or charging process, while the inorganic materials produced can improve the high-temperature shrinkage and puncture resistance of the separator, effectively improving the cycle performance of the battery. Attached Figure Description

[0104] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0105] Figure 1 This is a schematic diagram of the structure of a diaphragm according to an embodiment of this application;

[0106] Figure 2 This is a schematic diagram of the structure of a diaphragm according to an embodiment of this application;

[0107] Figure 3 This is a schematic diagram of a battery cell according to one embodiment of this application;

[0108] Figure 4 yes Figure 3 An exploded view of a battery cell according to one embodiment of this application is shown.

[0109] Figure 5 This is a schematic diagram of a battery module according to one embodiment of this application;

[0110] Figure 6 This is a schematic diagram of a battery pack according to one embodiment of this application;

[0111] Figure 7 yes Figure 6 An exploded view of a battery pack according to one embodiment of this application is shown;

[0112] Figure 8 This is a schematic diagram of an electrical device in which a single battery cell is used as a power source according to one embodiment of this application.

[0113] Explanation of icon numbers:

[0114] label name label name 100 diaphragm 4 Battery Module 10 Sodium-supplemented diaphragm 5 battery cell 20 Non-sodium supplementation diaphragm 51 case 1 Battery pack 52 Electrode assembly 2 Upper box 53 cover plate 3 Lower box

[0115] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0116] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0117] The following detailed description, with appropriate reference to the accompanying drawings, discloses the separator and its preparation method, the battery manufacturing process, the battery, and the power-consuming device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0118] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0119] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0120] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0121] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0122] Compared to lithium-ion batteries, which are made from scarce elements such as lithium, cobalt, and nickel, sodium-ion batteries have the advantage of abundant sodium resources and low raw material costs, making them highly promising for the energy storage field.

[0123] Sodium secondary batteries suffer from sodium loss during cycling.

[0124] For example, due to irreversible reactions such as the formation of the solid electrolyte interphase (SEI) film on the negative electrode surface during the first charge-discharge formation process, sodium ions will be lost from the positive electrode material, which will lead to a decrease in the energy density of the sodium secondary battery.

[0125] To address the aforementioned technical problems, this application provides a separator designed to improve the performance of sodium secondary batteries.

[0126] The membrane includes sodium-supplementing compounds, the chemical formulas of which are NaAlO2 and Na2M. n O 2n+1 At least one of the following, wherein M includes at least one of Ti, Zr, and Si, and 1 ≤ n ≤ 10.

[0127] In the structure of a secondary battery, the separator is one of the key internal components. The performance of the separator determines the battery's interface structure, internal resistance, and other characteristics, directly affecting the battery's capacity, cycle life, and safety performance. A high-performance separator plays a crucial role in improving the overall performance of the battery. The main function of the separator is to separate the positive and negative electrodes, preventing short circuits caused by contact between them. Additionally, it allows electrolyte ions to pass through.

[0128] The sodium-replenishing compound described in this application can decompose into sodium ions and inorganic materials during the formation or charging process. The sodium ions produced can replenish the sodium ions consumed during the formation or charging process, while the inorganic materials produced can improve the high-temperature shrinkage and puncture resistance of the separator, effectively improving the cycle performance of the battery.

[0129] In the above 1≤n≤10, the values ​​include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments and 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc., as well as the range values ​​between any two of the above point values.

[0130] In one embodiment, 1 ≤ n ≤ 5.

[0131] Sodium supplement compound Na2M n O 2n+1 In this context, 1≤n≤5, sodium-supplementing compounds with n in the above range are relatively common in nature, easy to obtain, and have low cost.

[0132] In the above 1≤n≤5, the values ​​include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, as well as 1, 2, 3, 4, 5, etc., and the range values ​​between any two of the above point values.

[0133] In one embodiment, Na2M n O 2n+1 Including Na2TiO3, Na2Ti2O5, and Na2Ti5O 11 Na2Ti6O 13 , Na2ZrO3, Na2SiO3, Na2Si2O5, Na2Si3O7, Na2Si5O 11 Na2Si 10 O 21 At least one of them.

[0134] Na2M in this application n O 2n+1 Including but not limited to Na2TiO3, Na2Ti2O5, Na2Ti5O 11 Na2Ti6O 13 , Na2ZrO3, Na2SiO3, Na2Si2O5, Na2Si3O7, Na2Si5O 11 Na2Si 10 O 21 At least one of them. It is understood that sodium-supplementing compounds can be oxidized and decomposed during formation or charging to yield sodium ions and inorganic materials.

[0135] For example, 4NaAlO2-4e-→2Al2O3+4Na + +O2; or, 2Na2TiO3-4e-→2TiO2+4Na + +O2; or, 2Na2Ti6O 13 -4e- → 12TiO2 + 4Na ++O2; or, 2Na2ZrO3-4e-→2ZrO2+4Na + +O2; or, 2Na2SiO3-4e-→2SiO2+4Na + +O2; or, 2Na2Si2O5-4e-→4SiO2+4Na + +O2; or, 2Na2Si3O7-4e-→6SiO2+4Na + +O2; or, 2Na2Si 10 O 21 -4e- → 20SiO2 + 4Na + +O2. That is, sodium-containing compounds can be oxidized and decomposed during formation or charging to yield sodium ions and inorganic materials.

[0136] The inorganic materials obtained from the decomposition have high hardness and high temperature resistance, which can improve the high temperature shrinkage performance of the diaphragm and reduce the problem of dendrite puncture of the diaphragm.

[0137] In one embodiment, the diaphragm includes a sodium-supplementing diaphragm, which includes a sodium-supplementing compound, and the thickness of the sodium-supplementing diaphragm ranges from 5 μm to 15 μm; preferably, from 7 μm to 13 μm; or, the diaphragm includes a base membrane and a sodium-supplementing layer disposed on the base membrane, the sodium-supplementing layer including a sodium-supplementing compound, and the thickness of the sodium-supplementing layer ranges from 5 μm to 15 μm; preferably, from 7 μm to 13 μm.

[0138] It is understandable that, such as Figure 1 and Figure 2 The diaphragm 100 in this application can be a single-layer diaphragm or a multi-layer diaphragm. When it is a single-layer diaphragm, the single-layer diaphragm is a sodium-supplementing diaphragm 10. For example, it is prepared by melt extrusion, where the sodium-supplementing diaphragm raw material (sodium-supplementing compound, polymer) and the base film raw material (polymer) are melt-co-extruded simultaneously. The resulting diaphragm includes a sodium-supplementing diaphragm composed of a polymer-coated sodium-supplementing compound and a base film bonded to the sodium-supplementing diaphragm, forming a double-layer diaphragm. At least one layer of the multi-layer diaphragm is a sodium-supplementing diaphragm 10, which includes a sodium-supplementing compound. The thickness of the sodium-supplementing diaphragm ranges from 5 μm to 15 μm, preferably from 7 μm to 13 μm. It is understood that the thickness of the sodium-supplementing diaphragm mentioned above refers to the thickness after hot pressing.

[0139] It is also understood that the separator includes a base membrane and a sodium-supplementing layer disposed on the base membrane. The sodium-supplementing layer includes a sodium-supplementing compound, and the thickness of the sodium-supplementing layer ranges from 5 μm to 15 μm; preferably, 7 μm to 13 μm. That is, the separator can be obtained by preparing the sodium-supplementing compound into a slurry and coating it onto the base membrane, with the thickness of the sodium-supplementing layer ranging from 5 μm to 15 μm; preferably, 7 μm to 13 μm.

[0140] When the thickness of the sodium-replenishing diaphragm or sodium-replenishing layer is within the above range, it can improve the sodium-replenishing capacity of the diaphragm, as well as the diaphragm's high-temperature resistance and puncture resistance.

[0141] The values ​​in the range of 5μm to 15μm include the minimum and maximum values ​​of this range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, etc., as well as the range values ​​between any two of the above point values.

[0142] The values ​​in the range of 7μm to 13μm include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, etc., as well as the range values ​​between any two of the above point values.

[0143] In one embodiment, the Dv50 value of the sodium-supplementing compound ranges from 100 nm to 3 μm, preferably from 100 nm to 1 μm.

[0144] Dv50 is the particle size at which the cumulative particle size distribution percentage of a sample reaches 50%. Physically, it means that 50% of the particles are larger than Dv50, and 50% are smaller. Dv50 is also called the median diameter or median particle size. Dv50 is often used to represent the average particle size of powders.

[0145] Dv50 can be tested using methods known in the art. As an example, GB / T19077-2016 can be referenced for characterization testing using a Malvern laser particle size analyzer, such as the Malvern Mastersizer-3000.

[0146] When the Dv50 of the sodium-supplementing compound is within the above range, it can help decompose the sodium-supplementing compound. In addition, it can alleviate the problem that excessively large particles of sodium-supplementing compounds can clog the micropores of the sodium-supplementing membrane, improve the problem that excessively small particles of sodium-supplementing compounds are prone to agglomeration, and facilitate the preparation of sodium-supplementing membranes of appropriate thickness.

[0147] The values ​​in the range of 100nm to 3μm include the minimum and maximum values ​​of this range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 500nm, 550nm, 800nm, 850nm, 1μm, 1.5μm, 2μm, 2.5μm, 3μm, etc., as well as the range values ​​between any two of the above point values.

[0148] The values ​​in the range of 100nm to 1μm include the minimum and maximum values ​​of this range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, 550nm, 600nm, 650nm, 700nm, 750nm, 800nm, 850nm, 900nm, 950nm, 1μm, etc., as well as the range values ​​between any two of the above point values.

[0149] In one embodiment, the diaphragm includes a sodium-supplementing diaphragm, which further includes a polymer coated on the surface of the sodium-supplementing compound.

[0150] Polymers are high molecular weight compounds composed of many identical, simple structural units linked together by repeated covalent bonds, such as polyethylene and polypropylene.

[0151] The polymer coating on the surface of the sodium-supplementing compound indicates that the sodium-supplementing compound in the sodium-supplementing membrane is coated with polymer, reducing the direct exposure of the sodium-supplementing compound to the outside.

[0152] The sodium-replenishing membrane also includes a polymer. The surface of the sodium-replenishing compound is coated with a polymer. By coating the sodium-replenishing compound with the polymer, the sodium-replenishing compound in the sodium-replenishing membrane is less likely to fall off the membrane, thus improving the sodium replenishment effect of the membrane in sodium secondary batteries.

[0153] Meanwhile, considering that sodium-supplemented compounds will oxidize and decompose into inorganic materials during formation or charging, polymer coating also reduces the problem of inorganic materials being released into the electrolyte.

[0154] In one embodiment, the sodium-supplemented membrane further includes a toughening agent; or, the sodium-supplemented membrane further includes a toughening agent, wherein the mass percentage of the toughening agent is 5% to 15% of the mass of the sodium-supplemented membrane, preferably 5% to 10%.

[0155] To improve the bonding strength between the sodium-supplementing compound and the polymer, the sodium-supplementing membrane also includes a toughening agent. Furthermore, the toughening agent accounts for 5% to 15% of the mass of the sodium-supplementing membrane, preferably 5% to 10%.

[0156] The values ​​in the range of 5% to 15% include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments and 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, etc., as well as the range values ​​between any two of the above point values.

[0157] The values ​​in the range of 5% to 10% include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments and 5%, 6%, 7%, 8%, 9%, 10%, etc., as well as the range values ​​between any two of the above point values.

[0158] In one embodiment, the sodium-supplementing membrane further includes a polymer, the polymer including at least one of polyethylene, polypropylene, polyethylene terephthalate, polyamide, and polyimide; and / or, the sodium-supplementing membrane further includes a toughening agent, the toughening agent including at least one of polytetrafluoroethylene, polyvinylidene fluoride, acrylic acid, polyethylene oxide, sodium carboxymethyl cellulose, styrene-butadiene rubber, hydroxypropyl methylcellulose, carboxylated styrene-butadiene latex, or polyvinyl alcohol.

[0159] The sodium-supplementing diaphragm in this application also includes polymers, including but not limited to at least one of polyethylene, polypropylene, polyethylene terephthalate, polyamide, and polyimide.

[0160] The sodium-supplemented diaphragm in this application also includes a toughening agent, which includes, but is not limited to, at least one of polytetrafluoroethylene, polyvinylidene fluoride, acrylic acid, polyethylene oxide, sodium carboxymethyl cellulose, styrene-butadiene rubber, hydroxypropyl methylcellulose, carboxylated styrene-butadiene latex, or polyvinyl alcohol.

[0161] In one embodiment, the diaphragm further includes a non-sodium-supplemented diaphragm, wherein the sodium-supplemented diaphragm is disposed on at least one side of the non-sodium-supplemented diaphragm.

[0162] Non-sodium-supplemented diaphragms, excluding sodium-supplemented compounds.

[0163] For example, such as Figure 2 As shown, the diaphragm 100 includes a sodium-supplemented diaphragm 10 and a non-sodium-supplemented diaphragm 20.

[0164] It is understood that the diaphragm also includes a non-sodium-supplemented diaphragm, that is, the diaphragm includes at least two layers, at least one of which is a non-sodium-supplemented diaphragm and at least one of which is a sodium-supplemented diaphragm, with the sodium-supplemented diaphragm located on at least one side of the non-sodium-supplemented diaphragm.

[0165] By using a multi-layered membrane, the membrane thickness can be adjusted, and the porosity of the non-sodium-supplemented membrane can be adjusted as needed. For example, the porosities of the sodium-supplemented membrane and the non-sodium-supplemented membrane can be set differently. In one embodiment, the porosity of the non-sodium-supplemented membrane is greater than that of the sodium-supplemented membrane to reduce the shedding of inorganic materials from the sodium-supplemented membrane into the electrolyte and to improve the overall permeability of the membrane, thereby enhancing the ion passage performance. For example, in one embodiment, the non-sodium-supplemented membrane can be a base membrane, and the prepared sodium-supplemented membrane can be adhered to the surface of the base membrane to form a membrane with at least two layers.

[0166] In one embodiment, a separator is disposed on one side of the positive electrode or the negative electrode, and a sodium-supplementing separator is disposed on the side of the non-sodium-supplementing separator facing the positive electrode.

[0167] It is understandable that in the process of battery manufacturing, the separator and the electrode need to be stacked in sequence. During the stacking of the separator and the electrode, the position of the separator in the electrode can be set as needed. For example, the separator can be placed between the positive electrode and the negative electrode.

[0168] In theory, the sodium-supplementing membrane can be placed on either side of the non-sodium-supplementing membrane. Considering that the sodium-supplementing compound will undergo an oxidative decomposition reaction during formation or charging, the potential of the positive electrode is higher than that of the negative electrode, which is more conducive to the decomposition of the sodium-supplementing compound. Therefore, in the preferred case, the sodium-supplementing membrane is placed on the side of the non-sodium-supplementing membrane facing the positive electrode.

[0169] In one embodiment, the total thickness of the diaphragm ranges from 13 μm to 30 μm; preferably, from 15 μm to 20 μm.

[0170] It is understood that the diaphragm in this application may be a multilayer diaphragm. When it is a multilayer diaphragm, at least one of the multilayer diaphragms is a sodium-supplementing diaphragm. The total thickness of the diaphragm in the multilayer diaphragm ranges from 13 μm to 30 μm; preferably, it is from 15 μm to 20 μm.

[0171] For example, a multilayer membrane includes a base membrane and a sodium-supplementing membrane disposed on at least one side of the base membrane. By placing the sodium-supplementing membrane on the base membrane, the overall thickness of the membrane can be increased. At the same time, the porosity of the base membrane can be greater than that of the sodium-supplementing membrane, thereby improving the overall puncture resistance and air permeability of the membrane.

[0172] The base membrane includes organic microporous membranes, and the materials of the base membrane include organic polymer materials, such as polyethylene, polypropylene, etc.

[0173] The base film is made of the same material as the polymer.

[0174] In theory, the material of the base membrane and the polymer can be the same or different, but it is preferred that they are the same to mitigate the problem of inconsistent ion conduction rates between the base membrane and the sodium-supplementing separator, which affects battery performance. For example, the base membrane material includes at least one of polyethylene, polypropylene, polyethylene terephthalate, polyamide, and polyimide.

[0175] The values ​​in the range of 13μm to 30μm include the minimum and maximum values ​​of this range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, 21μm, 22μm, 23μm, 24μm, 25μm, 26μm, 27μm, 28μm, 29μm, 30μm, etc., as well as the range values ​​between any two of the above point values.

[0176] The values ​​in the range of 15μm to 20μm include the minimum and maximum values ​​of this range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, as well as 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, etc., and the range values ​​between any two of the above point values.

[0177] In one embodiment, the mass percentage of the sodium-supplementing compound is 5% to 30% of the total mass of the diaphragm, preferably 10% to 20%.

[0178] It is understood that when the diaphragm is a single-layer diaphragm, the mass percentage of the sodium supplement compound is 5% to 30% of the mass of the single-layer diaphragm, preferably 10% to 20%.

[0179] When the diaphragm is a multilayer diaphragm, at least one layer is a sodium-supplementing diaphragm, and the mass percentage of the sodium-supplementing compound is 5% to 30% of the mass of the multilayer diaphragm, preferably 10% to 20%.

[0180] In other words, by setting the mass percentage of the sodium-replenishing compound relative to the mass of the membrane within the aforementioned range, the sodium ions lost during formation or charging can be replenished. It is understood that, for example, when the mass percentage of the sodium-replenishing compound relative to the mass of the membrane is greater than 8%, the sodium-replenishing compound will not be completely decomposed during the formation stage, and there will be a remaining sodium-replenishing compound used to decompose during the cycling process to replenish the sodium loss during the cycling process.

[0181] Furthermore, by setting the mass percentage of the sodium-supplementing compound within the aforementioned range, the inorganic materials generated from the decomposition of the sodium-supplementing compound can improve the high-temperature shrinkage and puncture resistance of the separator, effectively enhancing the battery's cycle performance. It is understood that setting the mass percentage of the sodium-supplementing compound within the aforementioned range can improve the sodium-supplementing effect and improve the battery's mass energy density. Taking all factors into consideration, this application uses a sodium-supplementing compound mass percentage of 5% to 30% of the total separator mass, preferably 10% to 20%.

[0182] The values ​​in the range of 5% to 30% include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, etc., as well as the range values ​​between any two of the above point values.

[0183] The values ​​in the range of 10% to 20% include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, etc., as well as the range values ​​between any two of the above point values.

[0184] In one embodiment, the porosity of the membrane ranges from 30% to 45%, preferably from 35% to 45%.

[0185] Considering the inorganic materials generated by sodium addition and decomposition, the porosity of the diaphragm is set between 30% and 45% to reduce the amount of inorganic materials falling into the electrolyte.

[0186] The values ​​in the range of 30% to 45% include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, etc., as well as the range values ​​between any two of the above point values.

[0187] The values ​​in the range of 35% to 45% include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, etc., as well as the range values ​​between any two of the above point values.

[0188] In one embodiment, the membrane includes a sodium-supplemented membrane and a non-sodium-supplemented membrane, the sodium-supplemented membrane being disposed on at least one side of the non-sodium-supplemented membrane, and the porosity of the sodium-supplemented membrane being less than or equal to the porosity of the non-sodium-supplemented membrane.

[0189] The porosity of the sodium-supplemented membrane and the non-sodium-supplemented membrane can be set to be the same or different. For example, in one embodiment, the porosity of the non-sodium-supplemented membrane is greater than that of the sodium-supplemented membrane to reduce the shedding of inorganic materials from the sodium-supplemented membrane into the electrolyte and to improve the overall permeability of the membrane, thereby enhancing the ion passage performance. When the porosities of the two membranes are different, and the porosity of the sodium-supplemented membrane is less than that of the non-sodium-supplemented membrane, the difference between the porosities of the two membranes is less than or equal to 5%.

[0190] In one embodiment, the porosity of the sodium-supplemented membrane ranges from 30% to 45%, preferably 35% to 45%; and / or, the porosity of the non-sodium-supplemented membrane ranges from 30% to 45%, preferably 37% to 45%.

[0191] Setting the porosity of the sodium-supplemented membrane within the above-mentioned range can reduce the shedding of inorganic materials from the membrane into the electrolyte.

[0192] The porosity of the non-sodium-supplemented diaphragm is set within the above range to improve the overall air permeability of the diaphragm and enhance the ion passage performance.

[0193] The values ​​in the range of 30% to 45% include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, etc., as well as the range values ​​between any two of the above point values.

[0194] The values ​​in the range of 35% to 45% include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, etc., as well as the range values ​​between any two of the above point values.

[0195] The values ​​in the range of 37% to 45% include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments and 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, etc., as well as the range values ​​between any two of the above point values.

[0196] In one embodiment, this application also provides a method for preparing the above-mentioned diaphragm, comprising: preparing raw materials for the diaphragm, wherein the raw materials for the diaphragm include a sodium-supplementing compound, the chemical formula of which is NaAlO2 or Na2M. n O 2n+1 At least one of the following, wherein M includes at least one of Ti, Zr, and Si, and 1 ≤ n ≤ 10; the raw materials for the diaphragm are prepared into a diaphragm.

[0197] Understandably, in one embodiment, the diaphragm can be a single-layer membrane, which can be produced using melt extrusion technology, with the polymer coating the surface of the sodium-supplementing compound. That is, the raw materials for the diaphragm (sodium-supplementing compound, polymer) are added to the extruder of the diaphragm extrusion apparatus for melt extrusion, and a composite membrane substrate is obtained through a cooling roller; the composite membrane substrate is then subjected to a cold drawing process to form holes, followed by heat treatment and a hot drawing process to form holes, and finally shaped to obtain a single-layer membrane.

[0198] In another embodiment, the diaphragm includes a base membrane and a sodium supplement layer disposed on the base membrane. In the raw material preparation step of the diaphragm, the sodium supplement compound can be prepared into a slurry and coated on the base membrane to obtain the diaphragm.

[0199] Alternatively, in another embodiment, the diaphragm can be a multilayer membrane, with a single-layer membrane produced by melt extrusion technology and then bonded to a base membrane to form a double-layer structure.

[0200] Alternatively, in another embodiment, a melt co-extrusion method is used, in which the diaphragm material (sodium supplement compound, polymer) and the base film material (polymer) are melt co-extruded simultaneously. The resulting diaphragm includes a membrane structure composed of a polymer-coated sodium supplement compound and a base film bonded to the membrane structure. Melt co-extrusion refers to an extrusion process in which several extruders simultaneously supply different plastic molten material flows to a composite die head and merge them into a multi-layer composite product.

[0201] In one embodiment, the process of preparing the membrane raw material into a membrane includes: adding the membrane raw material into the extruder of the extrusion membrane device, performing melt extrusion, and obtaining a composite membrane substrate through a cooling roller; performing a cold drawing process to form holes on the composite membrane substrate, performing heat treatment and a hot drawing process to form holes, and shaping to obtain a sodium-supplemented membrane.

[0202] An extrusion diaphragm device is used to push diaphragm raw material and extrude it into a film.

[0203] The sodium-supplemented separator prepared by melt extrusion includes a polymer-coated sodium-supplemented compound. This can alleviate the problem of inorganic materials generated by the decomposition of the sodium-supplemented compound falling off the separator into the electrolyte. It can also alleviate the problem of sodium-supplemented compound falling off the separator due to insufficient adhesion when it is coated on the separator during folding and rolling of the battery assembly, which would reduce the sodium-supplementation efficiency. Furthermore, this preparation method does not involve the use of organic solvents, which reduces production costs and environmental pollution.

[0204] Understandably, the preparation principle of the melt extrusion / stretching / heat setting method is that the polymer melt crystallizes under a high stress field, forming a lamellar structure that is perpendicular to the extrusion direction and parallel to it. Then, after heat treatment, an elastic material is obtained. After stretching, the lamellars of the hard and elastic polymer film separate, and a large number of microfibers appear, thereby forming a large number of microporous structures. After heat setting, a microporous membrane is obtained.

[0205] In one embodiment, the step of preparing the raw materials for the diaphragm further includes: stirring and mixing a sodium-supplementing compound, a polymer, and a toughening agent at a stirring speed of 400 r / min to 800 r / min for a stirring time of 0.5 h to 1 h to obtain the raw materials for the diaphragm.

[0206] In the preparation of the raw materials for the diaphragm, the sodium-supplementing compound, polymer, and toughening agent are stirred and mixed at a speed of 400 r / min to 800 r / min for 0.5 h to 1 h to obtain the raw materials for the sodium-supplemented diaphragm. Adding the toughening agent can improve the bonding strength between the sodium-supplementing material and the polymer, as well as the tightness of the bonding between the sodium-supplemented diaphragm and the base membrane.

[0207] The values ​​in the range of 400r / min to 800r / min include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 400r / min, 500r / min, 600r / min, 700r / min, 800r / min, etc., as well as the range values ​​between any two of the above point values.

[0208] The values ​​in the range of 0.5h to 1h include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h, etc., as well as the range values ​​between any two of the above point values.

[0209] In one embodiment, the temperature of the cooling roller is 15°C to 30°C; and / or, the thickness of the composite film substrate is 10 μm to 25 μm; and / or, the cold drawing process is performed under uniaxial stretching conditions of 15°C to 30°C and a stretching speed of 0.01 m / min to 0.1 m / min; and / or, the heat treatment conditions are heating at 15°C to 30°C below the polymer melting point for 30 min to 60 min; and / or, the hot drawing process conditions are uniaxial stretching under conditions of 100°C to 160°C, a stretching ratio of 1 to 5 times, and a stretching speed of 0.05 m / min to 0.5 m / min; and / or, the setting treatment conditions are: temperature 15°C to 30°C, time 0.5 h to 2 h.

[0210] It is understandable that the heat treatment conditions are heating at 15°C to 30°C below the polymer's melting point for 30 to 60 minutes. Assuming the polymer's melting point is 100°C, the heat treatment temperature is 70°C to 85°C, and the heating time is 30 to 60 minutes.

[0211] During the preparation of the diaphragm, the corresponding steps are made to meet the above conditions to obtain a diaphragm of appropriate thickness.

[0212] In one embodiment, this application also provides a battery manufacturing process, the battery manufacturing process including assembling a separator, a positive electrode, and a negative electrode, the separator including the separator as described above; or, the battery manufacturing process including assembling a separator, a positive electrode, and a negative electrode, the separator including the separator prepared by the separator manufacturing method described above.

[0213] In one embodiment, the process of assembling the separator, positive electrode, and negative electrode includes: injecting electrolyte into the battery after the separator, positive electrode, and negative electrode are packaged, and performing formation treatment on the battery.

[0214] Formation, in sodium battery formation, is the first charging process of a sodium battery after electrolyte injection. This process activates the active materials in the battery, thus activating the sodium battery.

[0215] Considering that the sodium-supplementing compound in this application can decompose into sodium ions and inorganic materials during the formation process, the battery after being packaged with the separator, positive electrode, and negative electrode is injected with electrolyte and subjected to formation treatment. This allows the sodium-supplementing compound in the separator to decompose, and the resulting sodium ions can replenish the sodium ions consumed during formation or charging. The resulting inorganic materials can improve the high-temperature shrinkage and puncture resistance of the separator, effectively improving the cycle performance of the battery.

[0216] In one embodiment, during the formation process of the battery, the formation voltage range is 3V to 4.2V; and / or, the formation temperature is 45°C to 80°C; and / or, the formation time is 2h to 5h; and / or, the vacuum degree of the formed battery ranges from 0.01MPa to 0.1MPa.

[0217] Using the voltage range mentioned above during the formation process helps to decompose sodium-containing compounds.

[0218] Within the aforementioned formation temperature range, the decomposition rate of sodium-supplemented compounds can be increased.

[0219] Within the aforementioned formation time range, sodium ions lost during the formation stage can be effectively replenished.

[0220] The aforementioned vacuum level inside the battery during the formation process can eliminate the gases generated during the decomposition of sodium compounds.

[0221] In addition, setting the battery vacuum level to the aforementioned level can reduce electrolyte loss and mitigate the problem of inorganic materials generated during the decomposition of sodium compounds being carried into the electrolyte from the polymer pores.

[0222] The values ​​in the range of 3V to 4.2V include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, as well as 3V, 3.2V, 3.5V, 3.8V, 4.0V, 4.2V, etc., and the range values ​​between any two of the above point values.

[0223] The values ​​of 45℃ and 80℃ mentioned above include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, etc., as well as the range values ​​between any two of the above point values.

[0224] The values ​​in the range 2h to 5h include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, as well as 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, etc., and the range values ​​between any two of the above point values.

[0225] The values ​​in the range of 0.01MPa to 0.1MPa include the minimum and maximum values ​​of this range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 0.01MPa, 0.02MPa, 0.03MPa, 0.04MPa, 0.05MPa, 0.06MPa, 0.07MPa, 0.08MPa, 0.09MPa, 0.1MPa, etc., as well as the range values ​​between any two of the above point values.

[0226] In one embodiment, after the formation process of the battery, the battery is further charged with a voltage ranging from 3V to 4.2V.

[0227] Considering that the sodium-supplementing compound in this application can decompose into sodium ions and inorganic materials during charging, setting the charging voltage range within the above-mentioned range can help decompose the sodium-supplementing compound.

[0228] In other words, the sodium-replenishing compound of this application not only decomposes during the formation stage to help replenish sodium ions during the formation stage, but also decomposes during the battery charging process to replenish sodium ions during the cycle.

[0229] The values ​​from 3V to 4.2V mentioned above include the minimum and maximum values ​​within this range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 3V, 3.2V, 3.5V, 3.8V, 4.0V, 4.2V, etc., as well as the range values ​​between any two of the above point values. In one embodiment, this application also provides a battery, the battery comprising a battery prepared by the battery manufacturing process described above.

[0230] In one embodiment, this application also provides an electrical device, which includes a battery as described above.

[0231] Since the battery adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be repeated here.

[0232] In addition, the following description of the battery (cell battery, battery module, battery pack) and electrical device of this application will be made with appropriate reference to the accompanying drawings.

[0233] In one embodiment of this application, a battery cell is provided.

[0234] Typically, a battery cell includes a positive electrode, a negative electrode, an electrolyte, and a separator. During charging and discharging, active ions move back and forth between the positive and negative electrodes, inserting and releasing. The electrolyte acts as a conductor of ions between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, primarily prevents short circuits between the positive and negative electrodes while allowing ions to pass through. The separator described above is the improved separator of this application.

[0235] The positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector.

[0236] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0237] In some embodiments, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0238] In some embodiments, the positive electrode film layer may optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0239] In some embodiments, the positive electrode film may optionally include a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0240] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0241] The negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector, the negative electrode film layer including a negative electrode active material.

[0242] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0243] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0244] In some embodiments, the negative electrode active material may be a negative electrode active material known in the art for use in batteries. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, etc. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0245] In some embodiments, the negative electrode film layer may optionally include a binder. The binder may 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).

[0246] In some embodiments, the negative electrode film may optionally include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0247] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0248] In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as the negative electrode active material, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto the negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0249] The electrolyte acts as a conductor of ions between the positive and negative electrodes. This application does not specify any particular type of electrolyte; it can be selected according to requirements.

[0250] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0251] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0252] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding or stacking process.

[0253] In some embodiments, the battery cell may include an outer packaging. This outer packaging can be used to encapsulate the electrode assembly and electrolyte described above.

[0254] In some embodiments, the outer packaging of the battery cell can be a rigid shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of the battery cell can also be a flexible package, such as a pouch. The material of the flexible package can be plastic; examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0255] This application does not impose any particular limitation on the shape of the battery cell; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 3 The example shown is a square-structured battery cell 5.

[0256] In some implementations, refer to Figure 4 The outer packaging may include a housing 51 and a cover 53. The housing 51 may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover 53 can be placed over the opening to close the receiving cavity. The positive electrode, negative electrode, and separator may be formed into an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is encapsulated within the receiving cavity. Electrolyte is immersed in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in a single battery cell 5 may be one or more, which can be selected by those skilled in the art according to specific practical needs.

[0257] In some implementations, individual battery cells can be assembled into a battery module. The number of individual battery cells contained in a battery module can be one or more, and the specific number can be selected by those skilled in the art based on the application and capacity of the battery module.

[0258] Figure 5 This is battery module 4, used as an example. (See reference...) Figure 5 In battery module 4, multiple battery cells 5 can be arranged sequentially along the length of battery module 4. Of course, they can also be arranged in any other manner. Furthermore, these multiple battery cells 5 can be fixed in place using fasteners.

[0259] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple battery cells 5 are received.

[0260] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0261] Figure 6 and Figure 7 This is battery pack 1 as an example. (See reference...) Figure 6 and Figure 7 The battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box includes an upper body 2 and a lower body 3, with the upper body 2 covering the lower body 3 to form a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0262] In addition, this application also provides an electrical device, which includes at least one of the secondary battery, battery module, or battery pack provided in this application. The secondary battery, battery module, or battery pack can be used as the power source of the electrical device or as the energy storage unit of the electrical device. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0263] As an electrical device, you can choose individual battery cells, battery modules, or battery packs according to your usage requirements.

[0264] Figure 8This is an example of an electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of individual battery cells, a battery pack or battery module can be used.

[0265] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a single battery cell as their power source.

[0266] Example

[0267] Example 1

[0268] Preparation of the diaphragm:

[0269] Sodium-supplementing compound NaAlO2, polypropylene, and toughening agent PVDF with an average particle size of 200 nm were premixed in a planetary mixer at a mass ratio of 15:75:10 for 40 min at 600 r / min. The mixture was then added to a diaphragm extrusion device for melt extrusion, and after passing through a cooling roller at 25 °C, a composite membrane substrate with a thickness of 20 μm was obtained. The composite membrane substrate was subjected to a unidirectional cold drawing process at 20 °C and a stretching speed of 0.08 m / min, followed by heat treatment at 130 °C for 40 min, and then unidirectional hot drawing at 130 °C and a stretching speed of 0.35 m / min. Finally, the membrane was set at 23 °C for 1 h to obtain a diaphragm with a thickness of 13 μm.

[0270] Battery manufacturing:

[0271] Na3V2(PO4)2F3 positive electrode active material, polyvinylidene fluoride (PVDF) and conductive agent acetylene black were dispersed and dissolved in N-methylpyrrolidone (NMP) solvent at a mass ratio of 90:5:5. The solution was uniformly coated on Al foil current collector as positive electrode, and artificial graphite material was used as negative electrode. NaPF6+EMC+EC electrolyte system was selected. The solution was assembled with the above-mentioned separator to form a full cell.

[0272] Preparation of positive electrode sheet

[0273] The Na3V2(PO4)2F3 positive electrode active material, the above-mentioned titanium-doped carbon-coated sodium orthosilicate material, the binder PVDF and the conductive agent acetylene black are dispersed and dissolved in NMP solvent in a mass ratio of 88:2:5:5 to form a uniformly dispersed slurry. The slurry is then uniformly coated on an aluminum foil current collector, and after drying, cold pressing and slitting, the positive electrode sheet is obtained.

[0274] Preparation of negative electrode sheet

[0275] The active material artificial graphite, conductive agent carbon black, binder styrene-butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC) are dissolved in deionized water at a weight ratio of 96.2:0.8:0.8:1.2 and mixed evenly to prepare a negative electrode slurry. The negative electrode slurry is uniformly coated onto the negative electrode current collector copper foil once or multiple times, and then dried, cold-pressed, and slit to obtain the negative electrode sheet.

[0276] Preparation of electrolyte

[0277] In an argon atmosphere glove box (H2O < 0.1 ppm, O2 < 0.1 ppm), the organic solvents ethylene carbonate (EC) and ethyl methyl carbonate (EMC) are mixed evenly at a volume ratio of 3 / 7. 12.5% ​​NaPF6 sodium salt is added and dissolved in the organic solvent, and the mixture is stirred evenly.

[0278] Preparation of sodium-ion batteries

[0279] In Example 1, the positive electrode, separator, and negative electrode are stacked in sequence, with the separator acting as a separator between the positive and negative electrodes. The resulting bare cell is then wound, tabs are welded onto it, and the cell is placed in an aluminum casing. It is then baked at 100°C to remove moisture, followed by the injection of electrolyte and sealing to obtain a non-charged battery. This non-charged battery then undergoes a series of processes including settling, hot and cold pressing, formation (with a voltage of 3.4V, a formation temperature of 69°C, a formation time of 3.5 hours, and a vacuum degree of 0.05MPa), shaping, and capacity testing to obtain the sodium-ion battery product of Example 1.

[0280] Example 2

[0281] Except for changing the mass ratio from 15:75:10 to 20:70:10, the other steps in Example 2 are the same as in Example 1.

[0282] Example 3

[0283] Except for changing the cold drawing and hot drawing processes to a cold drawing stretching rate of 0.05 m / min and a hot drawing stretching rate of 0.20 m / min, and finally obtaining a membrane thickness of 18 μm, the other steps in Example 4 are the same as in Example 1.

[0284] Examples 4 and 5

[0285] Based on Example 1, the thickness of the diaphragm was adjusted.

[0286] Examples 6 to 12

[0287] Based on Example 1, the types of sodium-supplementing compounds were adjusted.

[0288] Examples 13 and 14

[0289] Based on Example 1, the proportions of sodium-supplementing compound, polymer, and toughening agent were adjusted.

[0290] Examples 15 to 17

[0291] Based on Example 1, the Dv50 of the sodium-supplementing compound was adjusted.

[0292] Examples 18 and 19

[0293] Based on Example 1, the types of polymers and toughening agents were adjusted.

[0294] Example 20

[0295] NaAlO2 and Ketjen Black were mixed at a mass ratio of 85:15 as solutes, and N-methylpyrrolidone (NMP) of the same mass as the solutes was added to prepare a slurry. The slurry was coated onto the surface of a 10 μm polypropylene base membrane to form a sodium-supplementing layer with a coating thickness of 3 μm, thus forming a separator containing the sodium-supplementing layer. Except for the separator, the assembly steps of the full cell were the same as in Example 1.

[0296] Comparative Example 1

[0297] Based on Example 1, no sodium compound was added to the diaphragm, and a polypropylene membrane was used as the diaphragm.

[0298] Performance testing

[0299] Membrane robustness test:

[0300] Using a Type I testing apparatus, the prepared diaphragm sample was placed on a copper shaft with a diameter of 2 mm and subjected to a bending performance test at a speed of 180° / s for 100 s. The detached sodium-filled layer was collected, weighed, and the detachment rate was calculated, categorized into five levels: A, detachment rate ≤3%, essentially no detachment; B, detachment rate 3% to 6%; C, detachment rate 6% to 10%; D, detachment rate 10% to 20%; E, detachment rate greater than 20%. The experiment was conducted in accordance with standard GB / T 6742-2007 (Bending Test of Paints and Varnishes).

[0301] Thermal shrinkage performance test of the diaphragm:

[0302] Referring to standard ISO 14616-1997 "Heat-shrinkable films of polyethylene, ethylene copolymers and mixtures thereof - Determination of shrinkage stress", the FST-02 film heat shrinkage rate tester was used. The sample was cut into strips of 15mm × 130mm, and the heat shrinkage rate of the diaphragm after heat treatment at 130℃ for 30min was tested.

[0303] Battery performance test

[0304] Battery capacity retention test

[0305] Taking Example 1 as an example, the battery capacity retention rate test process is as follows: At 25°C, the battery corresponding to Example 1 is charged to 4.3V at a constant current of 1 / 3C, then charged to a current of 0.05C at a constant voltage of 4.3V, left to rest for 5 minutes, and then discharged to 2.8V at 1 / 3C. The resulting capacity is recorded as the initial capacity C0. The above steps are repeated for the same battery, and the discharge capacity Cn of the battery after the nth cycle is recorded. Then, the battery capacity retention rate after each cycle is Pn = Cn / C0 * 100%. In this test process, the first cycle corresponds to n = 1, the second cycle corresponds to n = 2, ..., the 200th cycle corresponds to n = 200. The battery capacity retention rate data corresponding to the examples and comparative examples in Tables 1 and 2 are the data measured after 500 cycles under the above test conditions, i.e., the value of P500.

[0306] Table 1. List of diaphragm parameters

[0307]

[0308]

[0309] Table 2. Separator and corresponding sodium-ion battery performance

[0310]

[0311] As can be seen from the table above, comparing the comparative examples and the comparative examples, the addition of a sodium-supplementing compound to the separator improves the cycle performance of the battery. Comparing Examples 1 to 19 with Example 20, Examples 1 to 19 are separators prepared using an extrusion separator apparatus, while Example 20 involves coating the separator with a slurry made from the sodium-supplementing compound. The separator prepared using the extrusion separator apparatus exhibits better cycle performance than that of Example 20.

[0312] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural transformations made using the contents of the specification and drawings of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the scope of patent protection of the present invention.

Claims

1. A diaphragm, characterized in that, The membrane includes a sodium-supplemented membrane, which comprises a sodium-supplemented compound, including Na2SiO3, Na2Si2O5, Na2Si3O7, and Na2Si5O. 11 Na2Si 10 O 21 At least one of them; The sodium-supplementing membrane also includes inorganic materials, which are obtained by oxidative decomposition of the sodium-supplementing compound during formation or charging, and the inorganic materials include SiO2.

2. The diaphragm as described in claim 1, characterized in that, The Dv50 value of the sodium-supplementing compound ranges from 100 nm to 3 μm.

3. The diaphragm as described in claim 2, characterized in that, The Dv50 value of the sodium-supplementing compound ranges from 100 nm to 1 μm.

4. The diaphragm according to any one of claims 1 to 3, characterized in that, The thickness of the sodium-supplementing diaphragm ranges from 5 μm to 15 μm.

5. The diaphragm as described in claim 4, characterized in that, The thickness of the sodium-supplementing diaphragm ranges from 7 μm to 13 μm.

6. The diaphragm according to any one of claims 1 to 3, characterized in that, The sodium-supplementing membrane also includes a polymer that coats the surface of the sodium-supplementing compound.

7. The diaphragm as described in claim 4, characterized in that, The sodium-supplemented diaphragm also includes a toughening agent; Alternatively, the sodium-supplemented diaphragm may further include a toughening agent, wherein the toughening agent accounts for 5% to 15% of the mass of the sodium-supplemented diaphragm.

8. The diaphragm as described in claim 7, characterized in that, The toughening agent accounts for 5% to 10% of the mass of the sodium-supplemented diaphragm.

9. The diaphragm as described in claim 4, characterized in that, The sodium-supplementing membrane also includes a polymer, which includes at least one of polyethylene, polypropylene, polyethylene terephthalate, polyamide, and polyimide. And / or, the sodium-supplemented diaphragm further includes a toughening agent, the toughening agent being at least one selected from polytetrafluoroethylene, polyvinylidene fluoride, acrylic acid, polyethylene oxide, sodium carboxymethyl cellulose, styrene-butadiene rubber, hydroxypropyl methyl cellulose, carboxylated styrene-butadiene latex, or polyvinyl alcohol.

10. The diaphragm as claimed in claim 4, characterized in that, The diaphragm also includes a non-sodium-supplemented diaphragm, wherein the sodium-supplemented diaphragm is disposed on at least one side of the non-sodium-supplemented diaphragm.

11. The diaphragm as claimed in claim 10, characterized in that, The diaphragm is disposed on one side of the positive or negative electrode, and the sodium-supplementing diaphragm is disposed on the side of the non-sodium-supplementing diaphragm facing the positive electrode.

12. The diaphragm according to any one of claims 1 to 3, characterized in that, The total thickness of the diaphragm ranges from 13 μm to 30 μm.

13. The diaphragm as claimed in claim 12, characterized in that, The total thickness of the diaphragm ranges from 15 μm to 20 μm.

14. The diaphragm according to any one of claims 1 to 3, characterized in that, The mass percentage of the sodium-supplementing compound is 5% to 30% of the total mass of the diaphragm.

15. The diaphragm as claimed in claim 14, characterized in that, The mass percentage of the sodium-supplementing compound is 10% to 20% of the total mass of the diaphragm.

16. The diaphragm according to any one of claims 1 to 3, characterized in that, The porosity of the diaphragm ranges from 30% to 45%.

17. The diaphragm as claimed in claim 16, characterized in that, The porosity of the diaphragm ranges from 35% to 45%.

18. The diaphragm according to any one of claims 1 to 3, characterized in that, The membrane includes a sodium-supplemented membrane and a non-sodium-supplemented membrane, wherein the sodium-supplemented membrane is disposed on at least one side of the non-sodium-supplemented membrane, and the porosity of the sodium-supplemented membrane is less than or equal to the porosity of the non-sodium-supplemented membrane.

19. The diaphragm as claimed in claim 18, characterized in that, The difference between the porosity of the non-sodium-supplemented diaphragm and the porosity of the sodium-supplemented diaphragm is less than or equal to 5%.

20. The diaphragm as claimed in claim 18, characterized in that, The porosity of the sodium-supplementing diaphragm ranges from 30% to 45%. And / or, the porosity of the non-sodium-supplemented diaphragm ranges from 30% to 45%.

21. The diaphragm as claimed in claim 20, characterized in that, The porosity of the sodium-supplementing diaphragm ranges from 35% to 45%. And / or, the porosity of the non-sodium-supplemented diaphragm ranges from 37% to 45%.

22. A method for preparing a diaphragm as described in any one of claims 1 to 21, characterized in that, include: The raw materials for preparing the diaphragm include sodium-supplementing compounds, such as Na₂SiO₃, Na₂Si₂O₅, Na₂Si₃O₇, and Na₂Si₅O₂. 11 Na2Si 10 O 21 At least one of them; The raw materials for the diaphragm are prepared into a diaphragm.

23. The method for preparing the diaphragm as described in claim 22, characterized in that, The process of preparing the membrane from the raw materials includes: The raw material for the diaphragm is added to the extruder of the diaphragm extrusion device for melt extrusion, and a composite membrane substrate is obtained by passing it through a cooling roller; The composite membrane substrate is subjected to a cold drawing process to form holes, followed by a heat treatment and hot drawing process to form holes, and then shaped to obtain a sodium-supplemented diaphragm.

24. The method for preparing the diaphragm as described in claim 23, characterized in that, The steps for preparing the raw materials for the membrane also include: The sodium-supplementing compound, polymer, and toughening agent are stirred and mixed at a stirring speed of 400 r / min to 800 r / min for 0.5 h to 1 h to obtain the raw material for the diaphragm.

25. The method for preparing the diaphragm as described in claim 24, characterized in that, The temperature of the cooling roller is 15°C to 30°C; And / or, the thickness of the composite film substrate is 10 μm to 25 μm; And / or, the cold drawing process is performed under the conditions of uniaxial stretching at a temperature of 15°C to 30°C and a stretching speed of 0.01 m / min to 0.1 m / min; And / or, the heat treatment conditions are heating at 15°C to 30°C below the polymer melting point for 30 to 60 minutes; And / or, the hot-drawing process is performed under the following conditions: uniaxial stretching at a temperature of 100°C to 160°C, a stretching ratio of 1 to 5 times, and a stretching speed of 0.05 m / min to 0.5 m / min. And / or, the shaping treatment conditions are: temperature 15°C to 30°C, time 0.5h to 2h.

26. A battery manufacturing process, characterized in that, The battery manufacturing process includes assembling a separator, a positive electrode, and a negative electrode, wherein the separator comprises the separator as described in any one of claims 1 to 21; Alternatively, the battery manufacturing process includes assembling a separator, a positive electrode, and a negative electrode, wherein the separator is a separator prepared by the method described in any one of claims 22 to 25.

27. The battery manufacturing process as described in claim 26, characterized in that, The assembly process of the separator, positive electrode, and negative electrode includes: The battery, after being encapsulated with the separator, positive electrode, and negative electrode, is injected with electrolyte and then subjected to formation treatment.

28. The battery manufacturing process according to claim 27, characterized in that, In the formation process of the battery, the formation voltage range is 3V to 4.2V; And / or, the temperature of the formation is 45°C to 80°C; And / or, the formation time is 2 hours to 5 hours; And / or, the vacuum degree of the formed battery ranges from 0.01 MPa to 0.1 MPa.

29. The battery manufacturing process according to claim 27 or 28, characterized in that, After the formation process of the battery, the battery is further charged with a voltage range of 3V to 4.2V.

30. A battery, characterized in that, The battery includes a battery prepared using the manufacturing process of any one of claims 26 to 29.

31. An electrical device, characterized in that, The electrical device includes the battery as described in claim 30.

Images