Sodium-supplementing separator, method for preparing sodium-supplementing separator, sodium-ion battery, and electric device

Abstract

Disclosed in the present application are a sodium-supplementing separator, a method for preparing the sodium-supplementing separator, a sodium-ion battery, and an electric device. The sodium-supplementing separator comprises a sodium-supplementing agent, and further comprises a separator substrate and an adsorption layer, wherein the adsorption layer is used for adsorbing CO2 generated by the sodium-supplementing agent, and the adsorption layer is arranged on at least one side of the separator substrate. According to the present application, the sodium-supplementing separator comprises the sodium-supplementing agent, which can provide a positive electrode with active sodium; and the sodium-supplementing separator has an adsorption effect and can thus adsorb CO2 generated by the sodium-supplementing agent. When used in a sodium-ion battery, without affecting the normal working of a positive electrode, the sodium-supplementing separator absorbs residual CO2 gas left in a formation stage to inhibit the residual CO2 gas from penetrating through the separator and reacting with a negative electrode, thereby effectively inhibiting the influence thereof on the composition of an SEI film, and also avoids the phenomenon of battery swelling caused by the residual CO2 gas.

Description

Sodium supplementing separator, method for preparing sodium supplementing separator, sodium ion battery and electric device

[0001] This application claims priority to the Chinese patent application No. 202410833035.7, filed on June 25, 2024, and entitled "Sodium supplementing separator, method for preparing sodium supplementing separator, sodium ion battery and electric device", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the technical field of batteries, in particular to a sodium supplementing separator, a method for preparing a sodium supplementing separator, a sodium ion battery and an electric device. BACKGROUND

[0003] To improve the capacity and cycle stability of batteries, existing sodium ion batteries generally have a sodium supplementing requirement. One method for supplementing sodium is to add a positive electrode sodium supplementing agent. Currently, common positive electrode sodium supplementing agents include sodium carbonate (Na2CO3), sodium oxalate (Na2C2O4) and sodium subcarbonate (Na2C4O4), etc., however, the decomposition of these sodium supplementing agents will generate a large amount of CO2 gas. Although most of the CO2 gas can be discharged during the formation stage, there is still some CO2 gas present inside the battery, which may subsequently cause the battery to bulge or even react with the negative electrode through the separator, affecting the composition of the SEI film and thus affecting the cycle performance of the battery. SUMMARY

[0004] A series of concepts in simplified form are introduced in the content part of the application, which will be further described in detail in the specific embodiment part. The content part of the present application does not mean to attempt to limit the key features and necessary technical features of the claimed technical solutions, nor to attempt to determine the protection scope of the claimed technical solutions.

[0005] To at least partially solve the above problems, the present application provides a sodium supplementing separator, which contains a sodium supplementing agent and comprises:

[0006] a separator base layer; and

[0007] an adsorption layer for adsorbing CO2 generated by the sodium supplementing agent, the adsorption layer being arranged on at least one side of the separator base layer.

[0008] Optionally, the adsorption layer comprises an adsorbent, and the adsorbent is an organic compound containing an amino group.

[0009] Optionally, the adsorbent is an amino acid organic compound.

[0010] Optionally, the mass percentage content of the adsorbent in the adsorption layer is 1% to 15%.

[0011] Optionally, the adsorbent has a mass percentage content of 8% to 12% in the adsorption layer.

[0012] Optionally, the adsorption layer further comprises the sodium supplement agent, and the sodium supplement agent has a mass percentage content of 10% to 98% in the adsorption layer.

[0013] Optionally, the sodium supplement diaphragm further comprises a sodium supplement layer, and the sodium supplement layer is arranged on a side of the diaphragm base layer for facing the positive electrode, and the sodium supplement layer comprises the sodium supplement agent.

[0014] Optionally, the sodium supplement layer and the adsorption layer are respectively arranged on different sides of the diaphragm base layer or are jointly arranged on the same side of the diaphragm base layer.

[0015] Optionally, the adsorption layer is the outermost layer of the sodium supplement diaphragm, and the face density of the adsorption layer is 1 g / m 2 ~ 10 g / m 2 .

[0016] Optionally, the diaphragm base layer comprises at least one of a conventional diaphragm and a modified diaphragm, the modified diaphragm comprises a modified coating layer and a modified diaphragm layer, and the modified coating layer is one of an organic coating layer and an inorganic oxide coating layer.

[0017] According to another aspect of the present application, a method for preparing a sodium supplement diaphragm is provided, and the sodium supplement diaphragm is the sodium supplement diaphragm of any one of the above aspects, and the method comprises applying an adsorbent and an auxiliary agent to at least one side of a diaphragm substrate for facing a positive electrode after mixing.

[0018] Optionally, the method comprises applying an adsorbent, a sodium supplement agent and an auxiliary agent to one side of a diaphragm substrate for facing a positive electrode after mixing.

[0019] Optionally, the method comprises:

[0020] mixing an adsorbent and an auxiliary agent to obtain a first mixture;

[0021] mixing a sodium supplement agent and an auxiliary agent to obtain a second mixture; and

[0022] applying the first mixture and the second mixture to the same side of a diaphragm substrate, and a layer formed by the first mixture is located on one side of a layer formed by the second mixture, or applying the first mixture and the second mixture to different sides of a diaphragm substrate respectively, wherein the second mixture is located on one side of a diaphragm substrate for facing a positive electrode.

[0023] According to still another aspect of the present application, a sodium ion battery is provided, and the sodium ion battery comprises a positive electrode, a negative electrode and the sodium supplement diaphragm of any one of the above aspects.

[0024] Optionally, the sodium supplementing diaphragm comprises an adsorption layer containing a sodium supplementing agent, which is arranged on the side of the diaphragm base layer facing the positive electrode,

[0025] or the sodium supplementing diaphragm comprises a sodium supplementing layer, which is arranged on the side of the diaphragm base layer facing the positive electrode.

[0026] According to still another aspect of the present application, there is provided a power utilization device comprising the sodium ion battery of any one of the above aspects.

[0027] According to the sodium supplementing diaphragm, the sodium ion battery and the method for preparing the sodium supplementing diaphragm of the present application, the sodium supplementing diaphragm contains a sodium supplementing agent, which can provide active sodium for the positive electrode; and the sodium supplementing diaphragm has an adsorption effect, which can adsorb CO2 generated by the sodium supplementing agent. When applied to the sodium ion battery, the residual CO2 gas in the formation stage is adsorbed without affecting the normal operation of the positive electrode, effectively inhibiting the penetration of the residual CO2 gas through the diaphragm and the reaction with the negative electrode, affecting the composition of the SEI film, and also avoiding the drumming phenomenon caused by the residual CO2 gas. BRIEF DESCRIPTION OF DRAWINGS

[0028] The following drawings of the present application are hereby incorporated into the present application as part of the present application for the purpose of understanding the present application. The embodiments of the present application and the description thereof shown in the drawings are used to explain the principles of the present application.

[0029] In the drawings:

[0030] Fig. 1 is a schematic structural diagram of a sodium supplementing diaphragm according to one embodiment of the present application;

[0031] Fig. 2 is a schematic structural diagram of a sodium supplementing diaphragm according to another embodiment of the present application;

[0032] Fig. 3 is a schematic structural diagram of a sodium supplementing diaphragm according to still another embodiment of the present application;

[0033] Fig. 4 is a schematic structural diagram of a sodium supplementing diaphragm according to still another embodiment of the present application;

[0034] Fig. 5 is a schematic structural diagram of a sodium supplementing diaphragm according to still another embodiment of the present application.

[0035] Legend of reference signs: 10: sodium supplementing diaphragm; 11: diaphragm base layer; 12: adsorption layer; 13: sodium supplementing layer. DETAILED DESCRIPTION

[0036] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to one skilled in the art that the present application can be practiced without one or more of these specific details. In other instances, well-known features have not been described in detail to avoid obscuring aspects of the present application.

[0037] For a thorough understanding of the present application, reference is made to the following description taken in conjunction with the accompanying drawings. It is apparent that the application can be practiced without one or more of the specific details set forth herein. Certain terminology is used in the description and the claims that shall not be interpreted as limiting unless otherwise indicated.

[0038] It is to be understood that the terminology used herein is for the purpose of describing the particular embodiments only and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0039] The ordinal numbers such as "first" and "second" used in the present application are merely identifiers but do not have any other meaning, for example, a particular order. Also, for example, the term "first member" itself does not imply the existence of a "second member", and the term "second member" itself does not imply the existence of a "first member".

[0040] It is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "inner", "outer" and similar terms are used for illustrative purposes only and are not intended to be limiting.

[0041] The exemplary embodiments according to this application will now be described in detail with reference to the accompanying drawings. The exemplary embodiments, however, can be implemented in various forms, and should not be construed as being limited to the implementations set forth herein. It will be understood that the exemplary embodiments are provided so that this application will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art.

[0042] The present application provides a sodium-ion battery, which comprises a positive electrode, a negative electrode and a sodium-supplementing separator. The sodium-supplementing separator can provide active sodium for the positive electrode. FIGS. 1-5 respectively schematically show different embodiments of the sodium-supplementing separator 10 of the present application. As shown in FIGS. 1-5, the present application also provides a novel sodium-supplementing separator 10 containing a sodium-supplementing agent, which can provide active sodium for the positive electrode; and the sodium-supplementing separator 10 has an adsorption function, which can adsorb CO2 generated by the sodium-supplementing agent.

[0043] Specifically, the sodium-supplementing separator 10 of the present application comprises a separator base layer 11 and an adsorption layer 12. The adsorption layer 12 is used to adsorb CO2 generated by the sodium-supplementing agent, and the adsorption layer 12 is arranged on at least one side of the separator base layer 11. The adsorption layer 12 can be directly applied to the side of the separator base layer 11; alternatively, other layers, such as the sodium-supplementing layer 13 mentioned below, can exist between the adsorption layer 12 and the separator base layer 11.

[0044] The separator base layer 11 comprises at least one of a conventional separator and a modified separator. The conventional separator or the modified separator is usually selected to constitute the separator base layer 11, that is, one type of separator material is selected to constitute the separator base layer 11. The ordinary separator is one of a glass fiber separator, a non-woven fabric separator, a polyolefin separator and other suitable separators. Among them, the non-woven fabric separator uses an organic polymer non-woven fabric.

[0045] The modified separator comprises a modified coating layer and a modified separator layer, and the modified coating layer is one of an organic coating layer and an inorganic oxide coating layer. Therefore, it can also be said that the modified separator comprises one of an organic coating modified separator and an inorganic oxide coating modified separator. The organic matter in the organic coating layer comprises at least one of vinylidene fluoride-hexafluoropropylene copolymer, cellulose and polydopamine and other suitable organic matters. The inorganic matter in the inorganic oxide coating layer comprises at least one of metal oxides such as aluminum oxide and non-metal oxides such as silicon dioxide.

[0046] The sodium-supplementing agent in the present application can be contained in the adsorption layer 12 or form an independent coating layer.

[0047] FIGS. 1 and 2 respectively schematically show different embodiments of the sodium-supplementing separator 10, in which the sodium-supplementing agent is contained in the adsorption layer 12, and the difference is that FIG. 1 shows that one layer of adsorption layer 12 containing the sodium-supplementing agent is applied to one side of the separator base layer 11; FIG. 2 shows that two layers of adsorption layer 12 are arranged, and the adsorption layer 12 is respectively applied to the two sides of the separator base layer 11, the sodium-supplementing agent is contained in one layer of adsorption layer 12, and the sodium-supplementing agent is schematically represented by small particles and the adsorbent is schematically represented by large particles; the other layer of adsorption layer 12 does not contain the sodium-supplementing agent. In the two embodiments, the adsorption layer 12 containing the sodium-supplementing agent is located on the side of the separator base layer 11 facing the positive electrode.

[0048] Specifically, one layer of the adsorption layer 12 includes a sodium supplement agent, an adsorbent and an auxiliary agent. The sodium supplement agent, the adsorbent and the auxiliary agent are mixed thoroughly, and then the formed mixture is applied to one side of the diaphragm base material constituting the diaphragm base layer 11. The adsorbent is uniformly dispersed in the adsorption layer 12; the sodium supplement agent is uniformly dispersed in the adsorption layer 12. Alternatively, another layer of the adsorption layer 12 includes the adsorbent and the auxiliary agent. The adsorbent and the auxiliary agent are mixed thoroughly, and then the formed mixture is applied to the other side of the diaphragm base material.

[0049] The sodium supplement agent includes sodium carbonate (Na2CO3), sodium oxalate (Na2C2O4) and sodium squarate (Na2C4O4), etc., that is, the sodium supplement agent is a compound with a molecular formula of Na x C y O z (x, y and z are all integers, and x≥1, y≥1, z≥1). The mass percentage of the sodium supplement agent in the adsorption layer 12 is 10% to 98%, for example, can be 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 98%, etc. The addition of the sodium supplement agent makes it possible to supplement sodium to the sodium ion battery to compensate for the sodium loss caused by the formation of SEI on the surface of the negative electrode, therefore, the sodium supplement agent needs to be as much as possible to improve the sodium supplement effect of the battery. In view of the above, the mass percentage of the sodium supplement agent in the adsorption layer 12 is preferably 85% to 90%.

[0050] The adsorbent is an organic compound containing amino group. Exemplarily, the adsorbent is an amino acid organic compound. For example, an amino acid salt (RCH(NH2)COOM, wherein M represents a salt element). Alternatively, the adsorbent is, for example, ethylenediamine, methylamine and other organic compounds containing amino group. The amino group (NH2-) in the adsorbent can react with CO2 to generate carbamic acid (ester), that is, RNH2+ CO2→ RNHCOO - . The free state CO2 is converted into a compound, so that the sodium supplement diaphragm 10 can realize chemical adsorption of CO2. The mass percentage of the adsorbent in the adsorption layer 12 is 1% to 15%, for example, can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, etc. The purpose of the adsorbent is to adsorb the residual CO2 gas not discharged in the synthesis stage, and this part of residual CO2 gas is less, therefore, the content of the adsorbent should not be too high, otherwise it will affect the electrochemical performance of the battery, and at the same time reduce the energy density of the battery. Preferably, the mass percentage of the adsorbent in the adsorption layer 12 is 8% to 12%. The adsorption layer 12 is the outermost layer of the sodium supplement diaphragm 10, further said is the layer closest to the positive electrode. The area density of the adsorption layer 12 can be 1 g / m 2 ~ 10 g / m 2 , for example, 1 g / m 2 , 2 g / m2 , 3 g / m 2 , 4 g / m 2 , 5 g / m 2 , 6 g / m 2 , 7 g / m 2 , 8 g / m 2 , 9 g / m 2 , 10 g / m 2 , and so on.

[0051] The auxiliary agent can include a binder and other auxiliary agents for forming the coating. The binder can be, for example, polyvinylidene fluoride (PVDF). The binder can have a mass percentage of 1% to 5% of the adsorption layer 12, for example, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, and so on. The amount of the binder should not be too high, otherwise it will also affect the electrochemical performance of the battery. Preferably, the binder has a mass percentage of 2% to 3% of the adsorption layer 12.

[0052] The sodium supplement, the adsorbent, and the binder are stirred in a solvent in a certain proportion, then coated on the surface of the separator, and after drying, a sodium supplement separator is obtained. The sodium supplement separator is assembled with a positive electrode and a negative electrode, then electrolyte is injected, and finally a finished battery is obtained. The positive electrode includes, for example, one or more of sodium iron pyrophosphate (NFPP), layered oxides, prussian blue compounds, and polyanion compounds, the negative electrode includes, for example, hard carbon, the solvent includes, for example, N-methyl pyrrolidone (NMP), the solvent of the electrolyte includes, for example, a mixture of ethylene carbonate (EC) and propylene carbonate (PC) in a volume ratio of 1:1, and the solute includes, for example, 1 mol / L of sodium hexafluorophosphate, and the areal density of the positive electrode is 110 to 130 g / m 2 , for example, 110 g / m 2 , 112 g / m 2 , 114 g / m 2 , 116 g / m 2 , 118 g / m 2 , 120 g / m 2 , 122 g / m 2 , 124 g / m 2 , 126 g / m 2 , 128 g / m 2 , 130 g / m 2 , and so on.

[0053] The sodium supplement diaphragm 10 provided by the embodiment firstly focuses on the treatment of residual CO2 and proposes to use amino materials as adsorption materials and blend with sodium supplement agents to form a mixture, which is coated on the surface of the diaphragm and applied to sodium ion batteries. In the case of not affecting the normal operation of the positive electrode, the residual CO2 gas in the formation stage is adsorbed, effectively inhibiting the residual CO2 gas from penetrating the diaphragm and reacting with the negative electrode, affecting the composition of the SEI film, and also avoiding the phenomenon of battery bulging caused by residual CO2 gas.

[0054] FIGS. 3, 4 and 5 respectively schematically show different embodiments of the sodium supplement diaphragm 10. In the three embodiments, the sodium supplement agent forms an independent coating, i.e., a sodium supplement layer 13, and the difference is that the adsorption layer 12 and the sodium supplement layer 13 are located differently.

[0055] Specifically, the sodium supplement diaphragm 10 further comprises a sodium supplement layer 13, which is arranged on the side of the diaphragm base layer 11 for facing the positive electrode, and the sodium supplement layer 13 comprises a sodium supplement agent. The sodium supplement layer and the adsorption layer 12 are respectively arranged on different sides of the diaphragm base layer 11, or are jointly arranged on the same side of the diaphragm base layer 11. As shown in FIG. 3, the sodium supplement layer 13 is arranged on one side of the diaphragm base layer 11, and the adsorption layer 12 is arranged on the other side of the diaphragm base layer 11. Alternatively, as shown in FIG. 4, the sodium supplement layer 13 and the adsorption layer 12 are jointly arranged on the same side of the diaphragm base layer 11, and the sodium supplement layer 13 is arranged between the adsorption layer 12 and the diaphragm base layer 11. Alternatively, as shown in FIG. 5, the sodium supplement layer 13 and the adsorption layer 12 are jointly arranged on the same side of the diaphragm base layer 11, and the adsorption layer 12 is arranged between the sodium supplement layer 13 and the diaphragm base layer 11. Of course, if necessary and / or desired, two or more sodium supplement layers 13 can be provided, or two or more adsorption layers 12 can be provided, and the sodium supplement layers 13 and the adsorption layers 12 are arranged alternately.

[0056] According to another aspect of the present application, a sodium ion battery is provided, which comprises a positive electrode, a negative electrode and the above-mentioned sodium supplement diaphragm 10. The adsorption layer 12 containing the sodium supplement agent is arranged on the side of the diaphragm base layer 11 for facing the positive electrode. Alternatively, the sodium supplement layer 13 is arranged on the side of the diaphragm base layer 11 for facing the positive electrode.

[0057] According to still another aspect of the present application, an electric device is provided, which comprises the above-mentioned sodium ion battery.

[0058] According to yet another aspect of the present application, a method for preparing a sodium supplementing separator is provided, the sodium supplementing separator being the sodium supplementing separator 10 of any of the above aspects. The method comprises applying the adsorbent and the auxiliary agent to at least one side of the separator substrate after mixing. Thus, the mixture of the adsorbent and the auxiliary agent can form the adsorption layer 12, and the separator substrate can form the separator base layer 11. The method comprises applying the adsorbent, the sodium supplementing agent and the auxiliary agent to one side of the separator substrate facing the positive electrode after mixing. Thus, the mixture of the adsorbent, the sodium supplementing agent and the auxiliary agent can form the adsorption layer 12 containing the sodium supplementing agent, and the adsorption layer 12 is located on one side of the separator base layer 11, as shown in the embodiments of FIG. 1 and FIG. 2. The method further comprises applying the adsorbent and the auxiliary agent to the other side of the separator substrate after mixing. Thus, the mixture of the adsorbent and the auxiliary agent can form the adsorption layer 12, and the adsorption layer 12 is located on the other side of the separator base layer 11, as shown in the embodiment of FIG. 2.

[0059] Alternatively, the method comprises mixing the adsorbent and the auxiliary agent to obtain a first mixture; and mixing the sodium supplementing agent and the auxiliary agent to obtain a second mixture, as shown in the embodiments of FIG. 3 to FIG. 5. The method further comprises applying the first mixture and the second mixture to different sides of the separator substrate, respectively. Thus, the first mixture can form the adsorption layer 12 not containing the sodium supplementing agent, and the second mixture can form the sodium supplementing layer 13, and the adsorption layer 12 and the sodium supplementing layer 13 are located on two sides of the separator base layer 11, as shown in the embodiment of FIG. 3.

[0060] Optionally, the method further comprises applying the first mixture and the second mixture to the same side of the separator substrate, and the layer formed by the first mixture is located on the side of the layer formed by the second mixture. Thus, the first mixture can form the adsorption layer 12 not containing the sodium supplementing agent, and the second mixture can form the sodium supplementing layer 13, and the adsorption layer 12 and the sodium supplementing layer 13 are located on one side of the separator base layer 11 and are stacked and adjacent to each other, as shown in the embodiments of FIG. 4 and FIG. 5.

[0061] The method further comprises applying the second mixture to the side of the separator substrate first, and then applying the first mixture to the separator substrate coated with the second mixture and on the second mixture. Thus, the sodium supplementing layer 13 is located between the adsorption layer 12 and the separator base layer 11, as shown in the embodiment of FIG. 4. The method further comprises applying the first mixture to the side of the separator substrate first, and then applying the second mixture to the separator substrate coated with the first mixture and on the first mixture. Thus, the adsorption layer 12 is located between the sodium supplementing layer 13 and the separator base layer 11, as shown in the embodiment of FIG. 5.

[0062] Example 1

[0063] Na2C2O4 of 96.5% by mass, sodium glutamate of 0.5% by mass, and polyvinylidene fluoride of 3% by mass were added to N-methylpyrrolidone, and mixed by stirring. The mixed mixture was uniformly coated on one side of a polyolefin separator. After drying at 80°C for 24 hours, a sodium-supplemented separator was obtained. The face density of the adsorption layer was 3 g / m 2 .

[0064] A sodium-supplemented separator, a positive electrode composed of sodium iron pyrophosphate (NFPP), and a negative electrode composed of hard carbon were assembled, and then an electrolyte was injected, to finally obtain a finished battery.

[0065] Example 2

[0066] Na2C2O4 of 96% by mass, sodium glutamate of 1% by mass, and polyvinylidene fluoride of 3% by mass were added to N-methylpyrrolidone, and mixed by stirring. The mixed mixture was uniformly coated on one side of a polyolefin separator. After drying at 80°C for 24 hours, a sodium-supplemented separator was obtained. The face density of the adsorption layer was 3 g / m 2 .

[0067] A sodium-supplemented separator, a positive electrode composed of sodium iron pyrophosphate (NFPP), and a negative electrode composed of hard carbon were assembled, and then an electrolyte was injected, to finally obtain a finished battery.

[0068] Example 3

[0069] Na2C2O4 of 90% by mass, sodium glutamate of 7% by mass, and polyvinylidene fluoride of 3% by mass were added to N-methylpyrrolidone, and mixed by stirring. The mixed mixture was uniformly coated on one side of a polyolefin separator. After drying at 80°C for 24 hours, a sodium-supplemented separator was obtained. The face density of the adsorption layer was 3 g / m 2 .

[0070] A sodium-supplemented separator, a positive electrode composed of sodium iron pyrophosphate (NFPP), and a negative electrode composed of hard carbon were assembled, and then an electrolyte was injected, to finally obtain a finished battery.

[0071] Example 4

[0072] Na2C2O4 of 89% by mass, sodium glutamate of 8% by mass, and polyvinylidene fluoride of 3% by mass were added to N-methylpyrrolidone, and mixed by stirring. The mixed mixture was uniformly coated on one side of a polyolefin separator. After drying at 80°C for 24 hours, a sodium-supplemented separator was obtained. The face density of the adsorption layer was 3 g / m 2 .

[0073] A sodium supplement diaphragm, a positive electrode composed of sodium pyrophosphate iron (NFPP), and a negative electrode composed of hard carbon are assembled, and then an electrolyte is injected, and finally a finished battery is obtained.

[0074] Example 5

[0075] A sodium supplement diaphragm, a positive electrode composed of sodium pyrophosphate iron (NFPP), and a negative electrode composed of hard carbon are assembled, and then an electrolyte is injected, and finally a finished battery is obtained. 2 .

[0076] A sodium supplement diaphragm, a positive electrode composed of sodium pyrophosphate iron (NFPP), and a negative electrode composed of hard carbon are assembled, and then an electrolyte is injected, and finally a finished battery is obtained.

[0077] Example 6

[0078] A sodium supplement diaphragm, a positive electrode composed of sodium pyrophosphate iron (NFPP), and a negative electrode composed of hard carbon are assembled, and then an electrolyte is injected, and finally a finished battery is obtained. 2 .

[0079] A sodium supplement diaphragm, a positive electrode composed of sodium pyrophosphate iron (NFPP), and a negative electrode composed of hard carbon are assembled, and then an electrolyte is injected, and finally a finished battery is obtained.

[0080] Example 7

[0081] A sodium supplement diaphragm, a positive electrode composed of sodium pyrophosphate iron (NFPP), and a negative electrode composed of hard carbon are assembled, and then an electrolyte is injected, and finally a finished battery is obtained. 2 .

[0082] A sodium supplement diaphragm, a positive electrode composed of sodium pyrophosphate iron (NFPP), and a negative electrode composed of hard carbon are assembled, and then an electrolyte is injected, and finally a finished battery is obtained.

[0083] Example 8

[0084] Na2C2O4 of 82% by mass, sodium glutamate of 15% by mass, and polyvinylidene fluoride of 3% by mass were added to N-methylpyrrolidone, and mixed by stirring. The mixed mixture was uniformly coated on one side of a polyolefin separator. After drying at 80°C for 24 hours, a sodium-supplemented separator was obtained. The face density of the adsorption layer was 3 g / m2. 2 .

[0085] The sodium-supplemented separator, the NFPP positive electrode, and a negative electrode composed of hard carbon were assembled, and then an electrolyte was injected, to finally obtain a finished battery.

[0086] Example 9

[0087] Na2C2O4 of 81% by mass, sodium glutamate of 16% by mass, and polyvinylidene fluoride of 3% by mass were added to N-methylpyrrolidone, and mixed by stirring. The mixed mixture was uniformly coated on one side of a polyolefin separator. After drying at 80°C for 24 hours, a sodium-supplemented separator was obtained. The face density of the adsorption layer was 3 g / m2. 2 .

[0088] The sodium-supplemented separator, the NFPP positive electrode, and a negative electrode composed of hard carbon were assembled, and then an electrolyte was injected, to finally obtain a finished battery.

[0089] Example 10

[0090] Na2C2O4 of 85% by mass, sodium glycinate of 12% by mass, and polyvinylidene fluoride of 3% by mass were added to N-methylpyrrolidone, and mixed by stirring. The mixed mixture was uniformly coated on one side of a polyolefin separator. After drying at 80°C for 24 hours, a sodium-supplemented separator was obtained. The face density of the adsorption layer was 3 g / m2. 2 .

[0091] The sodium-supplemented separator, the NFPP positive electrode, and a negative electrode composed of hard carbon were assembled, and then an electrolyte was injected, to finally obtain a finished battery.

[0092] Example 11

[0093] Na2C2O4 of 85% by mass, ethylenediamine of 12% by mass, and polyvinylidene fluoride of 3% by mass were added to N-methylpyrrolidone, and mixed by stirring. The mixed mixture was uniformly coated on one side of a polyolefin separator. After drying at 80°C for 24 hours, a sodium-supplemented separator was obtained. The face density of the adsorption layer was 3 g / m2. 2 .

[0094] The sodium-added separator, NFPP positive electrode, and hard carbon negative electrode are assembled, and then the electrolyte is injected to obtain the finished battery.

[0095] Example 12

[0096] 85% Na₂CO₃, 12% monosodium glutamate, and 3% polyvinylidene fluoride were added to N-methylpyrrolidone and mixed thoroughly. The mixture was then uniformly coated onto one side of a polyolefin membrane. After drying at 80°C for 24 hours, a sodium-added membrane was obtained. The areal density of the adsorption layer was 3 g / m³. 2 .

[0097] The sodium-added separator, NFPP positive electrode, and hard carbon negative electrode are assembled, and then the electrolyte is injected to obtain the finished battery.

[0098] Example 13

[0099] Monosodium glutamate (MSG) at 98% by weight and polyvinylidene fluoride (PVDF) at 2% by weight were added to N-methylpyrrolidone and mixed thoroughly. The first mixture was then uniformly coated onto one side of a polyolefin membrane. Next, Na₂C₂O₄ at 97% by weight and PVDF at 3% by weight were added to N-methylpyrrolidone and mixed thoroughly. The second mixture was then uniformly coated onto the first mixture. After drying at 80°C for 24 hours, a sodium-added membrane was obtained. The areal density of the adsorption layer was 3 g / m³. 2 .

[0100] The sodium-added separator, NFPP positive electrode, and hard carbon negative electrode are assembled, and then the electrolyte is injected to obtain the finished battery.

[0101] Comparative Example 1

[0102] 85% Na₂C₂O₄, 12% conductive carbon, and 3% polyvinylidene fluoride (PVDF) were added to N-methylpyrrolidone and mixed thoroughly. The mixture was then uniformly coated onto one side of a polyolefin membrane. After drying at 80°C for 24 hours, a sodium-supplemented membrane was obtained. The areal density of the sodium-supplemented layer was 3 g / m³. 2 .

[0103] The sodium-added separator, NFPP positive electrode, and hard carbon negative electrode are assembled, and then the electrolyte is injected to obtain the finished battery.

[0104] Comparative Example 2

[0105] The polyolefin separator, NFPP positive electrode, and hard carbon negative electrode are assembled, and then an electrolyte is injected to obtain the finished battery.

[0106] Battery cycle performance test

[0107] The battery charge-discharge specific capacity test was carried out by using a charge-discharge tester. The battery was set to a charged state, i.e., the working electrode was desodiated, the charge current density was 0.1C, and the battery was charged to the cut-off voltage of 4.5V, i.e., stopped running, and the first charge specific capacity was calculated. The discharge current density was 0.1C, and the battery was discharged to the cut-off voltage of 2.0V, and the discharge ended, and the first discharge specific capacity was calculated.

[0108] First charge specific capacity (mAh / g) = first charge capacity / mass of active material

[0109] First discharge specific capacity (mAh / g) = first discharge capacity / mass of active material

[0110] Table 1

[0111] The test results show that:

[0112] Compared with Comparative Example 2, Examples 1 to 13 and Comparative Example 1 all have a significant sodium supplement effect, and the sodium supplement effect of the battery added with the adsorbent in Examples 1 to 13 is better than that of Comparative Example 1. And from the test results of Examples 1 to 9, it can be known that when the content of the adsorbent is a variable, increasing the content of the adsorbent can improve the sodium supplement effect.

[0113] When the mass percentage content of the adsorbent is from 0.5% to 1%, the sodium supplement effect has an upward fluctuation. When the mass percentage content of the adsorbent is from 15% to 16%, the sodium supplement effect has a downward fluctuation. Therefore, the mass percentage content of the adsorbent can be selected to be 1% to 15%.

[0114] When the mass percentage content of the adsorbent is 8%, the sodium supplement effect is obvious. When the mass percentage content of the adsorbent is 12%, the sodium supplement effect is better, and then the content of the adsorbent is continuously increased, and the sodium supplement effect is gently improved. The adsorbent can basically completely absorb the residual CO2 when the mass percentage content of the adsorbent is 12%. Therefore, the mass percentage content of the adsorbent is preferably 8% to 12%.

[0115] From the test results of Examples 6, 10 and 11, it can be known that the sodium supplement effect is not much different when the types of the adsorbent are different. From the test results of Examples 6 and 12, it can be known that the CO2 absorption effects of the adsorbent on different sodium supplement agents are different. From the test results of Example 13, it can be known that when the adsorbent and the sodium supplement agent form two separate layers respectively, the sodium supplement effect is also good relative to forming one mixed layer.

[0116] Therefore, the novel sodium supplement diaphragm described in the application can adsorb CO2 generated by the sodium supplement agent and does not affect the sodium supplement effect, and can be applied to a sodium ion battery as an ideal diaphragm.

[0117] The sequence of steps of the method of the embodiments of the present application can be adjusted, combined or deleted according to actual needs. The above-described processes are only examples. Unless an adverse effect occurs, various processing operations can be performed in a sequence different from that of the above-described processes. The sequence of steps of the above-described processes can also be increased, combined or deleted according to actual needs.

[0118] Unless otherwise defined, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present application. The features described herein in one embodiment can be applied to another embodiment, alone or in combination with other features, unless the features are not applicable in the other embodiment or are otherwise described.

[0119] The present application has been described by the above embodiments, but it should be understood that the above embodiments are only for the purpose of example and illustration, and the present application is not limited to the above embodiments, and more various modifications and modifications can be made according to the teachings of the present application, which all fall within the scope claimed by the present application.

Claims

1. A sodium-replenishing diaphragm, wherein, The sodium-supplementing diaphragm contains a sodium-supplementing agent and includes: Diaphragm base layer; and An adsorption layer is provided on at least one side of the membrane base layer for adsorbing CO2 generated by the sodium supplement.

2. The sodium-supplementing diaphragm according to claim 1, wherein, The adsorption layer includes an adsorbent, which is an organic compound containing an amino group.

3. The sodium-supplementing diaphragm according to claim 2, wherein, The adsorbent is an amino acid-based organic compound.

4. The sodium-supplementing diaphragm according to claim 2, wherein, The adsorbent accounts for 1% to 15% of the mass percentage of the adsorption layer.

5. The sodium-supplementing diaphragm according to claim 4, wherein, The adsorbent accounts for 8% to 12% of the mass of the adsorption layer.

6. The sodium-supplementing diaphragm according to claim 2, wherein, The adsorption layer further includes the sodium supplementing agent, which accounts for 10% to 98% of the mass percentage of the adsorption layer.

7. The sodium-supplementing diaphragm according to any one of claims 1 to 6, wherein, The sodium-supplementing membrane further includes a sodium-supplementing layer, which is disposed on the side of the membrane base layer facing the positive electrode, and the sodium-supplementing layer includes the sodium-supplementing agent.

8. The sodium-supplementing diaphragm according to claim 7, wherein, The sodium replenishment layer and the adsorption layer are located on different sides of the membrane base layer, or they are located on the same side of the membrane base layer.

9. The sodium-supplementing diaphragm according to any one of claims 1 to 6, wherein, The adsorption layer is the outermost layer of the sodium-supplementing membrane, and the areal density of the adsorption layer is 1 g / m³. 2 ~10g / m 2 .

10. The sodium-supplementing diaphragm according to any one of claims 1 to 6, wherein, The membrane base layer includes at least one of conventional membranes and modified membranes, and the modified membrane includes a modified coating and a modified membrane layer, wherein the modified coating is one of an organic coating and an inorganic oxide coating.

11. A method for preparing a sodium-supplementing membrane, wherein the sodium-supplementing membrane is the sodium-supplementing membrane according to any one of claims 1 to 10, wherein, The method includes applying an adsorbent and an additive mixed together to at least one side of a membrane substrate.

12. The method according to claim 11, wherein, The method involves mixing an adsorbent, a sodium supplement, and an additive and then applying the mixture to one side of the membrane substrate facing the positive electrode.

13. The method according to claim 11, wherein, The method includes: The adsorbent and the additive are mixed to obtain the first mixture; The sodium supplement and adjuvants are mixed to obtain a second mixture; and The first mixture and the second mixture are applied to the same side of the membrane substrate, with the layer formed by the first mixture located on one side of the layer formed by the second mixture, or the first mixture and the second mixture are applied to different sides of the membrane substrate, respectively. The second mixture is located on the side of the membrane substrate facing the positive electrode.

14. A sodium-ion battery, wherein, The sodium-ion battery includes a positive electrode, a negative electrode, and a sodium-replenishing separator according to any one of claims 1 to 10.

15. The sodium-ion battery according to claim 14, wherein, The sodium-supplementing membrane includes an adsorption layer containing a sodium-supplementing agent, the adsorption layer being disposed on the side of the membrane base layer facing the positive electrode. Alternatively, the sodium-supplementing membrane may include a sodium-supplementing layer disposed on the side of the membrane base layer facing the positive electrode.

16. An electrical appliance, wherein, The electrical device includes a sodium-ion battery according to claim 14 or 15.

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