Battery monomer, composite sodium supplement material and preparation method thereof, battery, electric device

Abstract

The application relates to a battery monomer, a composite sodium supplementing material and a preparation method thereof, a battery and a power utilization device. The battery monomer comprises a positive electrode sheet, the positive electrode sheet comprises a positive electrode film layer, the positive electrode film layer comprises a positive electrode active material and a porous conductive agent, and the pores of the porous conductive agent contain a sodium supplementing agent. By arranging that the pores of the porous conductive agent contain the sodium supplementing agent, the capacity improvement effect of the battery monomer can be effectively achieved, the sodium supplementing agent and the porous conductive agent are combined into an entirety and added into a sodium battery system, the excellent conductivity of the porous conductive agent improves the conversion efficiency of the sodium supplementing agent, and the battery capacity is further improved. The sodium supplementing agent and the porous conductive agent are combined into an entirety and added into the sodium battery system, the problem that the sodium supplementing agent is prone to gelling and blocking and difficult to process when directly added into the battery monomer system can be effectively improved, and thus the difficulty of industrial application of the sodium supplementing agent can be reduced.

Description

Technical Field

[0001] This application relates to a battery cell, a composite sodium-supplementing material and its preparation method, a battery, and an electrical device. Background Technology

[0002] Sodium-ion batteries, as an emerging sustainable energy storage technology, are characterized by low cost and environmental friendliness, and therefore their application has been increasingly developed in recent years.

[0003] Therefore, higher requirements are placed on the capacity of sodium-ion batteries. Summary of the Invention

[0004] The purpose of this application is to provide a battery cell, a composite sodium-supplementing material and its preparation method, a battery, and an electrical device.

[0005] The embodiments of this application are implemented as follows:

[0006] In a first aspect, embodiments of this application provide a single battery cell, comprising:

[0007] The positive electrode sheet includes a positive electrode film layer; the positive electrode film layer includes a positive electrode active material and a porous conductive agent.

[0008] The porous conductive agent contains a sodium-supplementing agent within its pores.

[0009] In the above technical solution, by setting the pores of the porous conductive agent to contain sodium replenishing agent, the capacity of sodium-ion batteries can be effectively improved. The sodium replenishing agent and the porous conductive agent are combined into a whole and added to the sodium battery system. The excellent conductivity of the porous conductive agent improves the conversion efficiency of the sodium replenishing agent, which is further beneficial to the battery capacity and cycle performance.

[0010] Furthermore, combining the sodium supplement with the porous conductive agent as a whole and adding it to the sodium battery system can effectively improve the problems of gelation and agglomeration and difficult processing that occur when the sodium supplement is directly added to the sodium-ion battery system, thereby reducing the difficulty of industrial application of the sodium supplement.

[0011] Furthermore, in the above technical solution, by setting the pores of the porous conductive agent to contain a sodium replenishing agent, compared with the conventional high-temperature carbon coating solution, it can effectively avoid the decomposition of some sodium replenishing agents that are easily decomposed at low temperatures, thereby improving the sodium replenishment effect; furthermore, since the above technical solution does not require high-temperature sintering, it has fewer processing steps, lower costs, and is more conducive to industrial application.

[0012] In some optional implementations, when the discharge capacity of a single cell reaches more than 95% of its nominal capacity at 0.33C, the content of sodium supplement in the positive electrode film is 0.01% to 0.05% by mass.

[0013] In the above technical solution, by setting the content of sodium supplement in the positive electrode film layer to be 0.01% to 0.05% by mass, the effect of improving the capacity of the battery cell can be effectively achieved.

[0014] In some alternative embodiments, the porous conductive agent satisfies at least one of the following characteristics:

[0015] (1) D of porous conductive agents V 50 ranges from 1.2 μm to 10.4 μm;

[0016] (2) The porous conductive agent (D) V 90-D V 10) / D V 50 ranges from 0.83 to 3.01;

[0017] (3) The average pore size of the porous conductive agent is 2nm-50nm.

[0018] In the above technical solution, by setting the D of the porous conductive agent V 50 represents a particle size of 1μm to 10μm. This is beneficial for the processing performance of the slurry and for the battery capacity.

[0019] In some alternative embodiments, the porous conductive agent includes a porous carbon material. In some alternative embodiments, the sodium supplement agent includes a water-soluble sodium supplement agent.

[0020] In some alternative embodiments, the weak acid-strong base salt includes at least one of sodium nitrite, sodium citrate, sodium oxalate, or sodium carbonate.

[0021] In some alternative embodiments, the sodium supplement includes Na2NiO2, Na2S, NaN3, Na2CO3, Na2C4O4, and C. 10 H 12 At least one of N2Na4O8, Na2C6H2O6, NaNO2, Na2S2O3, Na2SO3, or Na2S2O5.

[0022] In some alternative implementations, the decomposition voltage of the sodium supplement is 3.3V to 4.3V.

[0023] In some alternative embodiments, the positive electrode active material includes at least one of polyanionic materials or layered oxides.

[0024] In some alternative embodiments, the positive electrode active material includes at least one of the following: sodium iron pyrophosphate, sodium iron pyrophosphate, sodium iron sulfate, sodium vanadium phosphate, and sodium fluorophosphate.

[0025] Secondly, embodiments of this application provide a composite sodium supplement material, comprising:

[0026] Porous conductive agent and sodium replenishing agent; the pores of the porous conductive agent contain sodium replenishing agent.

[0027] In some alternative embodiments, the porous conductive agent satisfies at least one of the following characteristics:

[0028] (1) D of porous conductive agents V 50 ranges from 1.2 μm to 10.4 μm;

[0029] (2) The porous conductive agent (D) V 90-D V 10) / D V 50 ranges from 0.83 to 3.01;

[0030] (3) The average pore size of the porous conductive agent is 2nm-50nm. In some optional embodiments, the pore volume of the composite sodium supplement material is 0.007ml / g to 0.14ml / g.

[0031] In some alternative implementations, the sodium supplement includes a water-soluble sodium supplement.

[0032] In some alternative embodiments, the sodium supplement includes Na2NiO2, Na2S, NaN3, Na2CO3, Na2C4O4, and C. 10 H 12 At least one of N2Na4O8, Na2C6H2O6, NaNO2, Na2S2O3, Na2SO3, or Na2S2O5.

[0033] In some alternative implementations, the decomposition voltage of the sodium supplement is 3.3V to 4.3V.

[0034] Thirdly, embodiments of this application provide a method for preparing a composite sodium supplement material, comprising:

[0035] The mixed solution of sodium supplement and porous conductive agent is recrystallized to precipitate the sodium supplement and allow it to enter the pores of the porous conductive agent.

[0036] In some alternative embodiments, recrystallizing the mixed solution of the sodium supplement and the porous conductive agent includes:

[0037] A saturated solution of sodium supplement is mixed with a porous conductive agent to obtain a mixed solution; the mixed solution is then stirred and heated. In some optional embodiments, the mass ratio of sodium supplement to porous conductive agent is (0.29-2.9):1.

[0038] In some optional embodiments, the pore volume of the porous conductive agent is greater than or equal to 0.2 ml / g; alternatively, the pore volume of the porous conductive agent is 0.5 ml / g to 2.0 ml / g.

[0039] In some alternative embodiments, the porous conductive agent satisfies at least one of the following characteristics:

[0040] (1) D of porous conductive agents V 50 is 1μm to 10μm; optionally, the D of the porous conductive agent V 50 is 6μm to 10μm;

[0041] (2) Porous conductive agents (D) V 90-D V 10) / D V 50 is 0.8 to 3;

[0042] (3) The average pore size of the porous conductive agent is 2nm-50nm.

[0043] In some alternative embodiments, the sodium supplement includes Na2NiO2, Na2S, NaN3, Na2CO3, Na2C4O4, and C. 10 H 12 At least one of N2Na4O8, Na2C6H2O6, NaNO2, Na2S2O3, Na2SO3, or Na2S2O5.

[0044] Fourthly, embodiments of this application provide a battery, which includes a battery cell provided in any of the foregoing embodiments.

[0045] Fifthly, embodiments of this application provide an electrical device, which includes a battery cell provided by any of the aforementioned embodiments. Attached Figure Description

[0046] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0047] Figure 1 This is a schematic diagram of a battery cell according to one embodiment of this application;

[0048] Figure 2 yes Figure 1 An exploded view of a battery cell according to one embodiment of this application is shown.

[0049] Figure 3This is a schematic diagram of a battery module according to one embodiment of this application;

[0050] Figure 4 This is a schematic diagram of a battery pack according to one embodiment of this application;

[0051] Figure 5 yes Figure 4 An exploded view of a battery pack according to one embodiment of this application is shown;

[0052] Figure 6 This is a schematic diagram of an electrical device that uses a battery as a power source according to one embodiment of this application;

[0053] Figure 7 This is a schematic diagram of a decomposed voltage test;

[0054] Figure 8 This is a schematic diagram of the positive electrode slurry filtration performance test.

[0055] icon:

[0056] 1 Battery pack; 2 Upper housing; 3 Lower housing; 4 Battery module; 5 Battery cell; 51 Housing; 52 Electrode assembly; 53 Top cover assembly. Detailed Implementation

[0057] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0058] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0059] In the description of the embodiments of this application, the technical terms "first", "second", etc. are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features.

[0060] In the description of the embodiments of this application, the technical terms "inner" and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0061] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0062] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0063] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the height, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall height, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0064] Due to the increasing demands on the capacity of sodium-ion batteries, there are numerous methods for improving their capacity. Common methods include using sodium-additives. However, adding sodium-additives to sodium-ion battery systems often leads to gelation and clumping; furthermore, the large particle size of the sodium-additives results in poor slurry processing performance. Other solutions address this by modifying the sodium-additives, adding the modified version to the sodium-ion battery system to mitigate the gelation problem. Common methods for modifying sodium-additives include carbon coating to address their moisture absorption and difficult particle size processing.

[0065] Research has revealed that some low-voltage sodium supplements, such as certain sodium / potassium nitrites, citrates, oxalates, and carbonates, while possessing the advantage of low-potential oxidative decomposition for sodium supplementation, are highly susceptible to hygroscopic deliquescence, leading to agglomeration. Furthermore, their large particle size and difficulty in grinding result in gelation (excessive water content) and poor filterability (large particles) in the slurry after addition, hindering their industrial application. Moreover, these sodium supplements are prone to low-temperature decomposition, while conventional coating modification processes often require sintering at temperatures above 500°C, which is unsuitable for processing sodium supplements prone to low-temperature decomposition. Additionally, the high-temperature sintering process is complex and costly.

[0066] Based on this, the first aspect of the embodiments of this application provides a battery cell, including:

[0067] The positive electrode sheet includes a positive electrode film layer; the positive electrode film layer includes a positive electrode active material and a porous conductive agent.

[0068] The porous conductive agent contains a sodium-supplementing agent within its pores.

[0069] In the above technical solution, by incorporating a sodium-replenishing agent within the pores of the porous conductive agent, the capacity of the sodium-ion battery can be effectively improved. Furthermore, the presence of a sodium-replenishing agent within the pores of the porous conductive agent allows the agent to integrate with the conductive agent as a single unit, which is then added to the positive electrode slurry. This effectively addresses the common problems of gelation and clumping when sodium-replenishing agents are added to sodium-ion battery systems, as well as the issues of poor filtration (large particles), thus reducing the difficulty of industrial application. Furthermore, by incorporating a sodium-replenishing agent within the pores of the porous conductive agent, compared to conventional high-temperature carbon coating methods, the above technical solution effectively avoids the decomposition of some low-temperature decomposable sodium-replenishing agents, thereby improving the sodium replenishment effect. Moreover, since the above technical solution does not require high-temperature sintering, it involves fewer processing steps, lowers costs, and is more conducive to industrial application.

[0070] In some embodiments of this application, the aforementioned battery cell includes a positive electrode, a negative electrode, an electrolyte, and a separator. The positive electrode includes a positive current collector and a positive electrode film; the negative electrode includes a negative current collector and a negative electrode film. During battery charging and discharging, active ions repeatedly insert and extract between the positive and negative electrode plates. The electrolyte acts as a conductor between the positive and negative electrode plates. The separator is disposed between the positive and negative electrode plates, primarily to prevent short circuits between the positive and negative electrodes, while simultaneously allowing ions to pass through.

[0071] Furthermore, in some embodiments of this application, when the discharge capacity of a single battery cell reaches more than 95% of its nominal capacity when discharged at 0.33C, the content of sodium supplement in the positive electrode film is 0.01% to 0.05% by mass percentage.

[0072] In the above technical solution, by setting the content of sodium supplement in the positive electrode film layer to be 1% to 3% by mass, the capacity and cycle performance of sodium-ion batteries can be effectively improved.

[0073] For example, in some embodiments of this application, the content of sodium supplement in the positive electrode film layer, by mass percentage, is 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, or any two of the aforementioned values.

[0074] In some embodiments of this application, the method for testing the content of the sodium supplement described above includes:

[0075] ICP (Inductively Coupled Plasma) testing is a powerful analytical technique used for qualitative and quantitative elemental analysis. An exemplary procedure for testing the content of sodium supplement using ICP is as follows:

[0076] (1) Take an appropriate electrode sheet and scrape 2g of sample with a ceramic knife;

[0077] (2) Then pour it into a clean beaker, weigh out 100g of deionized water, and soak for 24 hours to ensure that the water-soluble sodium supplement dissolves in the water.

[0078] (3) Filter the clear liquid and take 1g of the clear liquid;

[0079] (4) Then, referring to the inductively coupled plasma atomic emission spectrometry (ICP-OES) EPA 6010D-2018 standard test, the Na element content was obtained, in units of X%.

[0080] (5) Adding the dilution factor of 100, the amount of Na is 100*X% = X g; this is only the content of sodium, so the content of sodium supplement is X*M / 23g (where M is the molar mass of sodium supplement and 23 is the molar mass of sodium); finally, divide by the initial sample of 2g, so the content of sodium supplement is 100X*M / 46%.

[0081] It should be noted that the above-mentioned test method for sodium supplement content is for newly manufactured batteries, which refers to batteries whose discharge capacity reaches more than 95% of the nominal capacity when discharged at 0.33C.

[0082] The aforementioned "nominal capacity" is a term known in the art. Typically, the nominal capacity of a battery refers to the capacity indicated on the battery packaging, usually expressed in units of Ah (ampere-hours) or mAh (milliampere-hours). Furthermore, in some embodiments of this application, the D of the porous conductive agent... V 50 ranges from 1.2μm to 10.4μm.

[0083] In the above technical solution, by setting the D of the porous conductive agent V 50 has a particle size ranging from 1.2μm to 10.4μm. This is beneficial for the processing performance of the slurry and for the capacity of the battery.

[0084] Exemplary, in some embodiments of this application, the D of the porous conductive agent V 50 is 1.2μm, 1.3μm, 1.4μm, 1.5μm, 1.6μm, 1.7μm, 1.8μm, 2μm, 2.5μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 10.1μm, 10.2μm, 10.3μm, 10.4μm or any two of the aforementioned values.

[0085] Furthermore, in some embodiments of this application, the porous conductive agent (SPAN): (D V 90-D V 10) / D V 50 ranges from 0.83 to 3.01.

[0086] For example, in some embodiments of this application, the porous conductive agent (SPAN) is 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.90, 0.92, 0.94, 0.95, 0.98, 0.98, 0.98, 1.00, 1.05, 1.08, 1.1, 1.12, 1.15, 1.18, 1.20, 1.22, 1.25, 1.28, 1.30, 1.50, 1.80, 1.90, 2.00, 2.20, 2.50, 2.80, 2.90, 2.50, 3.00, 3.01 or a range between any two of the aforementioned values.

[0087] Particle size distribution width (SPAN) is another indicator that characterizes the width of particle distribution. SPAN is often used to characterize asymmetric particle systems, especially when the particle diameter distribution is significantly skewed.

[0088] The formula for calculating SPAN is as follows: (D V 90-D V 10) / D V 50; The higher the SPAN value, the wider the particle size distribution.

[0089] The above "D" V 50. D V 10. D V 90. D V "99" is a well-known term in the art, representing the particle size corresponding to a cumulative volume distribution percentage of 10%, 50%, 90%, and 99% for porous conductive agents. This size can be determined using instruments and methods known in the art. For example, it can be determined using a laser particle size analyzer, referring to GB / T19077-2016. The testing instrument can be a Mastersizer 3000 laser particle size analyzer from Malvern Instruments Ltd., UK.

[0090] In the above technical solution, the porous conductive agent (SPAN) has a wide particle size distribution in the range of 0.83 to 3.01, which is beneficial to the processing performance of the slurry and the capacity of the battery.

[0091] Furthermore, in some embodiments of this application, the average pore size of the porous conductive agent is 2nm-50nm.

[0092] For example, in some embodiments of this application, the average pore size of the porous conductive agent is 2nm, 3nm, 5nm, 8nm, 10nm, 12nm, 15nm, 18nm, 20nm, 22nm, 25nm, 30nm, 32nm, 35nm, 38nm, 40nm, 42nm, 45nm, 48nm, 50nm, or a range between any two of the aforementioned values.

[0093] The above-mentioned "average pore diameter of porous conductive agent" is: d = 4V / S, where d is the average pore diameter, V is the total pore volume, and S is the specific surface area.

[0094] The test method for the "average pore size of porous conductive agents" mentioned above can refer to GB / T21650.2-2008 for testing the mesopore and macropore volumes of materials, and further refer to GB / T 21650.3-2011 for testing the micropore volume of materials. The average pore size is 4 × total pore volume / specific surface area. That is, it is assumed that the pores of the material are simple columnar pores.

[0095] Furthermore, in some embodiments of this application, the porous conductive agent includes: porous carbon material.

[0096] Porous conductive agents, such as activated carbon, have a high porosity structure for "storing" sodium-containing agents, which not only solves the problem of difficult processing of highly hygroscopic surfactants, but also has good electronic conductivity, which can accelerate the decomposition efficiency of sodium-containing agents.

[0097] Furthermore, in some embodiments of this application, the sodium supplement includes a water-soluble sodium supplement.

[0098] In the above technical solution, the sodium replenishing agent includes a water-soluble sodium replenishing agent, which can better form an aqueous solution, thereby facilitating its subsequent entry into the pores of the porous conductive agent, which in turn benefits the processing of the positive electrode active material slurry and the battery capacity.

[0099] Furthermore, in some embodiments of this application, the sodium supplement includes a weak acid-strong base salt of sodium.

[0100] The above technical solution uses a sodium supplement agent comprising a weak acid-strong base salt, which is readily soluble in water and can better form an aqueous solution. This facilitates its subsequent entry into the pores of the porous conductive agent, thereby benefiting the processing of the positive electrode active material slurry and improving the battery capacity.

[0101] Furthermore, in some embodiments of this application, the weak acid-strong base salt includes at least one of nitrite, citrate, oxalate, or carbonate.

[0102] In the above technical solution, sodium nitrite, sodium citrate, sodium oxalate, and sodium carbonate are all readily soluble in water and can form a good sodium aqueous solution, which is beneficial for subsequent entry into the pores of the porous conductive agent, thereby improving the processing performance of activated carbon and the battery capacity.

[0103] For example, in some embodiments of this application, the sodium supplement is at least one of sodium nitrite, sodium citrate, sodium oxalate, or sodium carbonate; or in some embodiments of this application, the sodium supplement is a mixture of sodium nitrite and sodium citrate; or in some embodiments of this application, the sodium supplement is a mixture of sodium citrate and sodium oxalate; or in some embodiments of this application, the sodium supplement is a mixture of sodium oxalate and sodium carbonate; or in some embodiments of this application, the sodium supplement is a mixture of sodium nitrite, sodium citrate, sodium oxalate, and sodium carbonate; the raw materials in each of the above mixtures can be mixed in any proportion.

[0104] Furthermore, in some embodiments of this application, the sodium supplement includes Na2NiO2, Na2S, NaN3, Na2CO3, Na2C4O4, and C. 10 H 12 At least one of N2Na4O8, Na2C6H2O6, NaNO2, Na2S2O3, Na2SO3, or Na2S2O5.

[0105] In the above technical solution, Na2NiO2, Na2S, NaN3, Na2CO3, Na2C4O4, and C 10 H 12 N2Na4O8 (4Na.EDTA), Na2C6H2O6, NaNO2, Na2S2O3, Na2SO3, or Na2S2O5 are all readily soluble in water and can form good aqueous solutions of sodium, which is beneficial for subsequent entry into the pores of porous conductive agents, thereby improving the processing performance of activated carbon and the capacity of the battery.

[0106] Exemplary examples, in some embodiments of this application, the sodium supplement is selected from Na2NiO2, Na2S, NaN3, Na2CO3, Na2C4O4, C 10 H 12The sodium supplement is selected from any one of N2Na4O8, Na2C6H2O6, NaNO2, Na2S2O3, Na2SO3, or Na2S2O5; or in some embodiments of this application, the sodium supplement is selected from a mixture of Na2NiO2, Na3P, and Na2S; or in some embodiments of this application, the sodium supplement is selected from a mixture of NaN3, Na2CO3, Na2C4O4, and 4Na·EDTA; or in some embodiments of this application, the sodium supplement is selected from a mixture of Na2C6H2O6, NaNO2, Na2S2O3, and Na2SO3; or in some embodiments of this application, the sodium supplement is selected from a mixture of Na2NiO2 and Na2S2O5; the raw materials in each of the above mixtures can be mixed in any proportion.

[0107] Furthermore, in some embodiments of this application, the decomposition voltage of the sodium supplement is 3.3V to 4.3V.

[0108] In the above technical solution, the decomposition voltage of the sodium replenishing agent is 3.3V to 4.3V. This low-voltage sodium replenishing agent is more easily oxidized and decomposed. In the sodium battery system, it is compounded with the positive electrode active material, thereby forming a synergistic effect with the positive electrode active material to achieve the sodium replenishment effect, which is beneficial to improving the capacity of the battery cell.

[0109] For example, in some embodiments of this application, the decomposition voltage of the sodium supplement is 3.3V, 3.31V, 3.32V, 3.33V, 3.34V, 3.35V, 3.36V, 3.37V, 3.38V, 3.39V, 3.40V, 3.41V, 3.42V, 3.43V, 3.44V, 3.45V, 3.46V, 3.47V, 3.48V, 3.49V, 3.50V, 3.60V, 3.80V, 3.90V, 4.00V, 4.05V, 4.10V, 4.15V, 4.20V, 4.25V, 4.30V, or a range between any two of the aforementioned values.

[0110] Furthermore, in some embodiments of this application, the aforementioned "decomposition voltage of the sodium supplement" refers to:

[0111] Decomposition voltage refers to the minimum voltage required to decompose an electrolyte at the electrode to generate electrolytic products.

[0112] Furthermore, in some embodiments of this application, the term "decomposition voltage of the sodium supplement" has a meaning known in the art and can be tested using methods known in the art. An exemplary test method is as follows: Sodium supplement: conductive carbon: binder, mixed in a 7:2:1 ratio by mass, is applied to the electrode sheet, then cut to form a coin cell, and charged to 4.6V using a 5mA current, referring to… Figure 7 ,like Figure 7 As shown, a decomposition plateau appears at 3.45V, which corresponds to the decomposition voltage of the sodium supplement at 3.45V.

[0113] Furthermore, in some embodiments of this application, the positive electrode active material includes at least one of polyanionic materials or layered oxides.

[0114] In the above technical solution, polyanionic materials refer to materials that can insert and release sodium ions, and whose structure contains anionic groups that can interact with sodium ions. Polyanionic cathode materials typically have high electrochemical activity, enabling high-capacity sodium ion storage.

[0115] In some embodiments of this application, the aforementioned polyanionic material may be Na x-a A a V y-b M b (PO4)2(DO4)2F z-d Q d Wherein, element A represents an alkali metal element that substitutes for element Na, element M represents a metal element that substitutes for element V, element D represents a dopant element that substitutes for element P, and element Q represents a dopant element that substitutes for element F. Element D includes at least one of Si and S, and element Q includes at least one of Cl and O; 3.5 ≤ x ≤ 4.5, 0 ≤ a ≤ 0.15x, 0.8 ≤ y ≤ 1.1, 0 ≤ b ≤ 0.3y, 0.8 ≤ z ≤ 1.1, and 0 ≤ d ≤ 0.2z. Optionally, element A includes at least one of K and Li; element M includes at least one of Fe, Cr, Al, Sc, Ga, In, Ti, Zr, Mn, Zn, Ni, Cu, and Co.

[0116] In some embodiments of this application, the above-mentioned positive electrode active materials may be modified by doping and / or surface coating.

[0117] Furthermore, in some embodiments of this application, the above-mentioned positive electrode active material includes at least one of the following: sodium iron pyrophosphate, sodium iron pyrophosphate, sodium iron sulfate, sodium vanadium phosphate, and sodium fluorophosphate.

[0118] Further optionally, in some embodiments of this application, the sodium iron pyrophosphate class includes: sodium iron pyrophosphate, dopants of sodium iron pyrophosphate; exemplarily, iron site dopants of sodium iron pyrophosphate.

[0119] Further optionally, in some embodiments of this application, the iron-site doping element of sodium iron pyrophosphate includes at least one of Ti, V, Cr, Mn, Co, Ni, Ca, Mg, Al, or Nb.

[0120] Further optionally, in some embodiments of this application, the positive electrode active material can be selected from sodium iron pyrophosphate such as Na4Fe3(PO4)2P2O7(NFPP), sodium iron pyrophosphate such as sodium iron pyrophosphate Na2FeP2O7, sodium vanadium phosphate such as sodium vanadium phosphate Na3V2(PO4)3, sodium fluorophosphate such as Na2FePO4F, Na3V2(PO4)3.

[0121] Further optionally, in some embodiments of this application, sodium iron pyrophosphate includes: sodium iron pyrophosphate, dopants of sodium iron pyrophosphate; exemplarily, iron site dopants of sodium iron pyrophosphate.

[0122] Further optionally, in some embodiments of this application, the iron-site doping element of sodium iron pyrophosphate includes at least one of Ti, V, Cr, Mn, Co, Ni, Ca, Mg, Al, or Nb.

[0123] In other optional embodiments of this application, the sodium ferric sulfate, sodium vanadium phosphate, and sodium fluorophosphate described above also include similar doping methods.

[0124] Further, optionally, in some embodiments of this application, the above-mentioned layered oxide includes:

[0125] Na x MO2, where M is a transition metal element, such as nickel, cobalt, manganese, iron, copper, etc.

[0126] For example, in some embodiments of this application, the layered oxide described above can be a nickel-iron-manganese layered oxide; such as NaNi. 0.2 Fe 0.29 Mn 0.4 Cu 0.1 Ga 0.01 O2, NaNi 0.2 Fe 0.2 Mn 0.4 Cu 0.05 Ga 0.15 O2, NaNi 0.2 Fe 0.3 Mn 0.4 Cu 0.09 Ga 0.01 O2, NaNi 0.2 Fe 0.29 Mn 0.4 Zn 0.1 Ga 0.01 O2, NaNi 0.2 Fe 0.30 Mn 0.4 Mg 0.05 Ga 0.0 5O2, NaNi0.1 Feb 0.39 Mr 0.4 Cu 0.1 Ga 0.01 O2、NaFe 0.39 Mr 0.5 Cu 0.1 Ga 0.01 O2、NaNi 0.39 Feb 0.2 Mr 0.4 Ga 0.01 O2、NaNi 0.25 Feb 0.39 Mr 0.3 Cu 0.05 Ga 0.01 O2、Na 0.7 Ni 0.2 Feb 0.29 Mr 0.4 Cu 0.1 Ga 0.01 O2、NaNi 0.2 Feb 0.29 Mr 0.4 Cu 0.1 Dad 0.01 O2、NaNi 0.2 Feb 0.2 Mr 0.4 Cu 0.05 Dad 0.15 O2、NaNi 0.3 Feb 0.3 Mr 0.4 Cu 0.09 Dad 0.01 O2、NaNi 0.2 Feb 0.29 Mr 0.4 Zn 0.1 Dad 0.01 O2、NaNi 0.2 Feb 0.30 Mr 0.4 Mg 0.05 Dad 0.0 5O2、NaNi 0.3 Feb 0.19 Mr 0.4 Cu 0.1 Dad 0.01 O2、NaNi 0.1 Feb 0.39 Mr 0.4 Cu 0.1 Dad 0.01 O2、NaFe 0.39 Mr 0.5 Cu 0.1 Dad0.01 O2, NaNi 0.39 Mn 0.5 Zn 0.1 Ta 0.01 O2, NaNi 0.45 Fe 0.5 Cu 0.04 Ta 0.01 O2, NaNi 0.39 Fe 0.2 Mn 0.4 Ta 0.01 O2, Na 1.0 3Ni 0.2 Fe 0.29 Mn 0.4 Cu 0.1 Ta 0.01 O2, Na 0.7 Ni 0.2 Fe 0.29 Mn 0.4 Cu 0.1 Ta 0.01 O2, NaNi 0.25 Fe 0.39 Mn 0.3 Cu 0.05 Ta 0.0 At least one of 1O2.

[0127] During the charging and discharging process of a battery, sodium (Na) undergoes insertion / extraction and consumption, resulting in varying molar Na content at different discharge states. In the examples of cathode materials in this application, the molar Na content refers to the initial state of the material, i.e., the state before feeding. When the cathode material is applied to the battery system, the molar Na content changes after charge-discharge cycles.

[0128] In the examples of cathode materials in this application, the molar content of O is only a theoretical value. Oxygen release from the crystal lattice will cause changes in the molar content of oxygen, and the actual molar content of O will fluctuate.

[0129] Further optionally, in some embodiments of this application, the positive electrode film layer may also include a binder. As an example, the binder may include at least one selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0130] Further optionally, in some embodiments of this application, the conductive agent in the positive electrode film layer may include porous carbon materials and non-porous carbon materials; for example, porous carbon materials include activated carbon, etc.; non-porous carbon materials include at least one of acetylene black, carbon black, carbon nanotubes, graphene or carbon nanofibers.

[0131] Further optionally, in some embodiments of this application, the amount of the conductive agent (the conductive agent and the sodium supplement as a whole) added to the positive electrode slurry, by mass percentage, is 1% to 5%. Exemplarily, the amount of the conductive agent added to the positive electrode slurry, by mass percentage, is 1%, 1.1%, 1.2%, 1.5%, 1.8%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, 3.1%, 3.2%, 3.5%, 3.8%, 4%, 4.1%, 4.5%, 4.8%, 5%, or a range between any two of the aforementioned values.

[0132] In some embodiments of this application, the positive electrode slurry prepared above is coated on at least one surface of the positive electrode current collector, and after drying, cold pressing and other processes, a positive electrode sheet can be obtained.

[0133] 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.

[0134] 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.).

[0135] 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.

[0136] Some embodiments of this application provide a composite sodium supplement material, including:

[0137] Porous conductive agent and sodium replenishing agent; the pores of the porous conductive agent contain sodium replenishing agent.

[0138] In the above technical solution, the porous conductive agent contains a sodium-replenishing agent within its pores, allowing it to be added as a whole to the battery cell system. The porous conductive agent functions as a conductive agent, while the sodium-replenishing agent replenishes sodium. Simultaneously, the porous conductive agent acts as a carrier, embedding the sodium-replenishing agent within it. This not only solves the problem of difficult sodium-replenishing agent processing but also improves the high-efficiency conversion of the sodium-replenishing agent due to its superior conductivity.

[0139] Furthermore, in some embodiments of this application, the D of the porous conductive agent V 50 ranges from 1.2μm to 10.4μm.

[0140] Exemplary, in some embodiments of this application, the D of the porous conductive agent V 50 is 1.2μm, 1.3μm, 1.5μm, 2.0μm, 2.5μm, 2.8μm, 3.0μm, 3.5μm, 4.0μm, 4.5μm, 5.0μm, 5.5μm, 6.0μm, 6.5μm, 7.0μm, 7.5μm, 8.0μm, 8.5μm, 9.0μm, 9.5μm, 10.0μm, 10.1μm, 10.2μm, 10.3μm, 10.4μm, or any two of the aforementioned values.

[0141] Further optionally, the D of the porous conductive agent V 50 is 6.2μm~6.8μm.

[0142] Furthermore, in some embodiments of this application, the porous conductive agent (SPAN): (D V 90-D V 10) / D V 50 ranges from 0.83 to 3.01.

[0143] For example, in some embodiments of this application, the porous conductive agent (SPAN) is 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.90, 0.92, 0.94, 0.95, 0.98, 0.98, 0.98, 1.00, 1.05, 1.08, 1.1, 1.12, 1.15, 1.18, 1.20, 1.22, 1.25, 1.28, 1.30, 1.50, 1.80, 1.90, 2.00, 2.20, 2.50, 2.80, 2.90, 2.50, 3.00, 3.01 or a range between any two of the aforementioned values.

[0144] Furthermore, in some embodiments of this application, the average pore size of the porous conductive agent is 2nm-50nm.

[0145] For example, in some embodiments of this application, the average pore size of the porous conductive agent is 2nm, 3nm, 5nm, 8nm, 10nm, 12nm, 15nm, 18nm, 20nm, 22nm, 25nm, 30nm, 32nm, 35nm, 38nm, 40nm, 42nm, 45nm, 48nm, 50nm, or a range between any two of the aforementioned values.

[0146] Further optionally, in some embodiments of this application, the pore volume of the composite sodium supplement material is 0.007 ml / g to 0.14 ml / g.

[0147] For example, in some embodiments of this application, the pore volume of the composite sodium supplement material is 0.007 ml / g, 0.008 ml / g, 0.010 ml / g, 0.012 ml / g, 0.015 ml / g, 0.020 ml / g, 0.030 ml / g, 0.040 ml / g, 0.050 ml / g, 0.060 ml / g, 0.070 ml / g, 0.080 ml / g, 0.090 ml / g, 0.10 ml / g, 0.11 ml / g, 0.12 ml / g, 0.13 ml / g, 0.14 ml / g, or a range between any two of the aforementioned values.

[0148] Furthermore, in some embodiments of this application, the sodium supplement includes a water-soluble sodium supplement.

[0149] Furthermore, in some embodiments of this application, the sodium supplement includes Na2NiO2, Na2S, NaN3, Na2CO3, Na2C4O4, and C. 10 H 12 At least one of N2Na4O8, Na2C6H2O6, NaNO2, Na2S2O3, Na2SO3, or Na2S2O5.

[0150] Furthermore, in some embodiments of this application, the decomposition voltage of the sodium supplement is 3.3V to 4.3V.

[0151] Some embodiments of this application provide a method for preparing a composite sodium supplement material, including:

[0152] The mixed solution of sodium supplement and porous conductive agent is recrystallized to precipitate the sodium supplement and allow it to enter the pores of the porous conductive agent.

[0153] In the above technical solution, a mixed solution is obtained by mixing a saturated solution of sodium supplement with a porous conductive agent; the mixed solution is then recrystallized to precipitate the sodium supplement and allow it to enter the pores of the porous conductive agent; this allows the sodium supplement to be embedded in the porous conductive agent using a high-porosity conductive agent as a carrier, which not only solves the problem of difficult processing, but also improves the high-efficiency conversion efficiency of the sodium supplement due to the excellent conductivity of the conductive agent.

[0154] Furthermore, in some embodiments of this application, recrystallizing the mixed solution includes:

[0155] A saturated solution of sodium supplement is mixed with a porous conductive agent to obtain a mixed solution; the mixed solution is then stirred and heated.

[0156] In the above technical solution, heating the mixed solution allows the solvent to evaporate, thereby enabling the sodium supplement to enter the pores of the porous conductive agent. Alternatively, in the above technical solution, stirring and heating the mixed solution can further increase the solvent evaporation rate, thereby accelerating the entry of the sodium supplement into the pores of the porous conductive agent.

[0157] Furthermore, in some embodiments of this application, the mass ratio of sodium supplement to porous conductive agent is (0.29-2.9):1.

[0158] In the above technical solution, by setting the mass ratio of sodium replenishing agent to porous conductive agent to (0.29-2.9):1, it can be well combined with activated carbon within this range, filling more of the pores of the porous conductive agent, which is conducive to obtaining a better sodium replenishment effect, thereby improving the capacity of the battery cell.

[0159] For example, in some embodiments of this application, the mass ratio of sodium supplement to porous conductive agent is 0.29:1, 0.30:1, 0.32:1, 0.35:1, 0.38:1, 0.40:1, 0.45:1, 0.50:1, 0.55:1, 0.60:1, 0.65:1, 0.70:1, 0.75:1, 0.80:1, 0.90:1, 1:1, 1.2:1, 1.5:1, 1.8:1, 2:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1, or any two of the aforementioned values.

[0160] Furthermore, in some embodiments of this application, the pore volume of the porous conductive agent is greater than or equal to 0.2 ml / g.

[0161] In the above technical solution, by setting the pore volume of the porous conductive agent to be greater than or equal to 0.2 ml / g, more sodium supplement can be accommodated, allowing more sodium supplement to be embedded in the porous conductive agent. This not only solves the problem of difficult processing, but also improves the high efficiency conversion of sodium supplement by its excellent conductivity.

[0162] For example, in some embodiments of this application, the pore volume of the porous conductive agent is 0.2 ml / g, 0.21 ml / g, 0.22 ml / g, 0.23 ml / g, 0.24 ml / g, 0.25 ml / g, 0.26 ml / g, 0.27 ml / g, 0.28 ml / g, 0.29 ml / g, 0.3 ml / g, 0.32 ml / g, 0.35 ml / g, 0.38 ml / g, 0.4 ml / g, 0.45 ml / g, 0.46 ml / g, 0.46 ml / g, 0.46 ml / g, 0.46 ml / g, 0.48 ml / g. ml / g, 0.5ml / g, 0.55ml / g, 0.6ml / g, 0.65ml / g, 0.70ml / g, 0.75ml / g, 0.80ml / g, 0.85ml / g, 0.90ml / g, 0.95ml / g, 1.00ml / g, 1.10ml / g, 1.20ml / g, 1.30ml / g, 1.40ml / g, 1.50ml / g, 1.60ml / g, 1.70ml / g, 1.80ml / g, 1.90ml / g, 2.00ml / g, or a range between any two of the aforementioned values.

[0163] Furthermore, in some embodiments of this application, the pore volume of the porous conductive agent is 0.5 ml / g to 2.0 ml / g.

[0164] In the above technical solution, by setting the pore volume of the porous conductive agent to 0.5 ml / g to 2.0 ml / g, more sodium supplement can be accommodated, allowing more sodium supplement to be embedded in the porous conductive agent. This not only solves the problem of difficult processing, but also improves the high efficiency of sodium supplement conversion due to its excellent conductivity.

[0165] Furthermore, in some embodiments of this application, the "pore volume of the porous conductive agent" mentioned above refers to:

[0166] In some embodiments of this application, the term "pore volume of the porous conductive agent" has a well-known meaning in the art, referring to the volume of other substances that a porous material can hold under a certain pressure. Testing instruments include BET analyzers and automatic specific surface area and porosity analyzers (such as the Micromeritics ASAP series and Quantachrome Autosorb series). Nitrogen adsorption is typically used to determine the pore volume and pore size distribution of the material by measuring the amount of nitrogen adsorbed under different relative pressures.

[0167] Furthermore, in some embodiments of this application, the D of the porous conductive agent V 50 is 1μm to 10μm; optionally, the D of the porous conductive agent V 50 is 6μm to 8μm.

[0168] Exemplary, in some embodiments of this application, the D of the porous conductive agent V 50 is a range of 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm or any two of the aforementioned values.

[0169] Furthermore, in some embodiments of this application, the porous conductive agent (D V 90-D V 10) / D V 50 is 0.8 to 3.

[0170] Exemplary, in some embodiments of this application, the porous conductive agent (D V 90-D V 10) / D V 50 is a range of 0.8, 0.85, 0.9, 0.95, 1, 1.2, 1.5, 1.8, 2, 2.2, 2.5, 2.8, 3, or any two of the aforementioned values.

[0171] Furthermore, in some embodiments of this application, the sodium supplement includes Na2NiO2, Na2S, NaN3, Na2CO3, Na2C4O4, and C. 10 H 12 At least one of N2Na4O8, Na2C6H2O6, NaNO2, Na2S2O3, Na2SO3, or Na2S2O5.

[0172] [Negative electrode plate]

[0173] The negative electrode sheet includes a negative current collector and a negative electrode film layer formed on at least one surface of the negative current collector.

[0174] In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as 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 a negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0175] In some optional embodiments of this application, the aforementioned negative electrode active material may include at least one of the following: hard carbon, graphite, soft carbon, carbon fiber, silicon-based materials, tin-based materials, sodium titanate, or other metals that can form alloys with sodium, optionally, hard carbon.

[0176] 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 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 (copper, copper 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.).

[0177] 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).

[0178] 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.

[0179] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0180] In other embodiments, the current collector of the negative electrode sheet typically includes a current collector body and a base coating. The base coating can be disposed on at least one side of the current collector body. The base coating essentially does not contain negative electrode active material, but may include a small amount of carbon material. However, the carbon material forms a thin coating and cannot function as a negative electrode active material. When the current collector of the negative electrode sheet includes a base coating, the film layer can be disposed on the surface of the base coating away from the current collector. In this embodiment, the negative electrode sheet can be an electrode sheet without a negative electrode active material layer. For a negative electrode sheet without a negative electrode active material layer, when the current collector of the negative electrode sheet does not contain a base coating, the film layer can be disposed on the surface of at least one side of the current collector; when the current collector of the negative electrode sheet includes a base coating, the film layer can be disposed on the surface of the base coating away from the current collector.

[0181] In some embodiments, the film layer may further include a binder for fixing the additive to the negative electrode sheet. The type of binder is not particularly limited, and those skilled in the art can choose flexibly according to actual needs.

[0182] [Electrolytes]

[0183] This application does not impose any particular limitation on the type of electrolyte, which can be selected according to actual needs. For example, the electrolyte can be selected from at least one of solid electrolytes and liquid electrolytes (i.e., electrolyte solutions). This includes battery cells using electrolyte solutions and some battery cells using solid electrolytes.

[0184] The electrolyte plays a role in conducting ions between the positive and negative electrode plates.

[0185] In some embodiments, the electrolyte salt may be selected from at least one of sodium hexafluorophosphate, sodium tetrafluoroborate, sodium perchlorate, sodium hexafluoroarsenate, sodium difluorosulfonamide, sodium ditrifluoromethanesulfonamide, sodium trifluoromethanesulfonate, sodium difluorophosphate, sodium difluorooxalate borate, sodium dioxalate borate, sodium difluorodioxalate phosphate, and sodium tetrafluorooxalate phosphate.

[0186] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0187] 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.

[0188] [Isolation membrane]

[0189] In some embodiments, this application does not have a particular limitation on the type of separator membrane, and any known porous structure separator membrane with good chemical and mechanical stability can be selected.

[0190] In some embodiments, the material of the separator can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0191] In some embodiments of this application, the positive electrode, the negative electrode, and the separator can be formed into an electrode assembly 52 by a winding process or a stacking process.

[0192] 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.

[0193] 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.

[0194] 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 1 The example shown is a square-structured battery cell 5.

[0195] In some implementations, refer to Figure 2 The outer packaging may include a housing 51 and a cover plate 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 plate 53 can be placed over the opening to close the receiving cavity. An 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 the battery cell 5 may be one or more, which can be selected by those skilled in the art according to specific practical needs.

[0196] Some embodiments of this application provide a battery, including the battery cell provided in any of the foregoing embodiments.

[0197] In the above technical solutions, the term "battery" can be at least one of a battery cell, a battery module, or a battery pack.

[0198] For example, in some embodiments, battery cells can be assembled into battery modules, and the number of battery cells contained in a battery module 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 module.

[0199] Figure 3 This is battery module 4, used as an example. (See reference...) Figure 3 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.

[0200] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple battery cells 5 are received.

[0201] 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.

[0202] Figure 4 and Figure 5 This is battery pack 1 as an example. (See reference...) Figure 4 and Figure 5 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.

[0203] Some embodiments of this application provide an electrical device that includes a battery cell provided in any of the foregoing embodiments, or the electrical device includes a battery provided in any of the foregoing embodiments.

[0204] The battery cell, battery module, or battery pack can be used as a power source for the electrical device, or as an energy storage unit for 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.

[0205] As the electrical device, a single battery cell, a battery module, or a battery pack can be selected according to its usage requirements.

[0206] Figure 6 This 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 device's requirements for high power and high energy density, a battery pack or battery module can be used.

[0207] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can be powered by a battery.

[0208] Example

[0209] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0210] Example 1

[0211] A battery cell is provided, prepared according to the following steps:

[0212] [Preparation of positive electrode sheet]:

[0213] I. Preparation of prefabricated composite sodium supplement material:

[0214] Prepare a saturated sodium supplement solution:

[0215] (1) Add sodium supplement (NaNO2) to water and prepare a saturated solution of sodium supplement with a concentration of 22.4 g / 100 mL;

[0216] (2) Add activated carbon to the saturated solution obtained in step (1) and stir; the pore volume of the activated carbon is 0.5 ml / g, and the D of the activated carbon is... V 50 is 6μm; the mass ratio of activated carbon to sodium supplement is 1:1.

[0217] (3) Stirring and heating simultaneously, sodium supplementation agent is gradually released and fills the pores of activated carbon to prepare additive@activated carbon precursor;

[0218] (4) The additive@activated carbon precursor obtained in step (3) is further dried; dried at 105℃, weighed every 2 hours until the mass remains unchanged;

[0219] (5) The dried additive@activated carbon powder obtained in step (4) is further ground and passed through a 300-mesh sieve to obtain composite sodium supplement powder. See Table 1 and Table 2 for details of each parameter.

[0220] II. Forming of Positive Electrode Sheets

[0221] Aluminum foil is used as the current collector.

[0222] By mass ratio, the positive electrode active material (Na4Fe3(PO4)2P2O7), binder (polyvinylidene fluoride (PVDF)), and the aforementioned composite sodium-supplementing material powder were compounded in a ratio of 95:2.5:2.5 to obtain the positive electrode material. After adding it to the solvent N-methylpyrrolidone (NMP) and stirring until homogeneous, a positive electrode slurry was prepared. This slurry was then uniformly coated onto aluminum foil, with a single-sided coating weight of 0.3 g / 1540.25 mm. 2After drying, cold pressing to a density of 3.0 g / cc, winding, assembly, and formation processes, a positive electrode sheet is formed. Specific parameters are detailed in Tables 1 and 2.

[0223] [Preparation of negative electrode sheet]:

[0224] The negative electrode active material hard carbon, conductive agent acetylene black, binder styrene-butadiene rubber (SBCs), and thickener carboxymethyl cellulose (CMC) are thoroughly mixed in an appropriate amount of deionized water at a weight ratio of 90:5:4:1 to form a uniform negative electrode slurry. The negative electrode slurry is coated onto a negative electrode current collector copper foil with a thickness of 12μm, dried at 100℃, and then pressed to obtain a negative electrode sheet.

[0225] [Electrolyte preparation]:

[0226] In an argon-filled glove box, ethylene carbonate (EC), diethyl carbonate (DEC), and methyl ethyl carbonate (EMC) were mixed in a mass ratio of EC:DEC:EMC = 4:2:4, and then 1.0 mol / L sodium hexafluorophosphate (NaPF6) was added.

[0227] [Isolation membrane]:

[0228] The separator is a polyethylene separator.

[0229] [Battery Assembly]:

[0230] The positive electrode, separator, and negative electrode are stacked and wound in sequence to form a battery cell, which is then activated.

[0231] Activation process: (1) Charge to 3.0V at 0.1C rate; (2) Let stand for 10 min; (3) Charge to 4.3V at 0.1C; (4) Discharge to 2.0V at 0.33C; (5) Let stand for 10 min; (6) Charge to 3.0V at 0.33C.

[0232] Example 2-13

[0233] The difference from Example 1 is that the performance parameters of the sodium supplement, porous conductive agent, etc. are different, as detailed in Tables 1 and 2.

[0234] Comparative Example 1

[0235] The difference from Example 1 lies in the preparation of the positive electrode. The positive electrode of this comparative example is prepared as follows:

[0236] Aluminum foil is used as the current collector.

[0237] By mass ratio, the positive electrode active material (Na4Fe3(PO4)2P2O7), binder (polyvinylidene fluoride (PVDF)), and activated carbon were compounded in a ratio of 95:2.5:2.5 to obtain the positive electrode material. After adding it to the solvent N-methylpyrrolidone (NMP) and stirring until homogeneous, a positive electrode slurry was prepared. This slurry was then uniformly coated onto aluminum foil, with a single-sided coating weight of 0.3 g / 1540.25 mm. 2 After drying, cold pressing to a density of 3.0 g / cc, winding, assembly, and formation processes, a positive electrode sheet is formed. See Tables 1 and 2 for detailed parameters.

[0238] Comparative Example 2

[0239] The difference from Example 1 lies in the preparation of the positive electrode. The positive electrode of this comparative example is prepared as follows:

[0240] Aluminum foil is used as the current collector.

[0241] By mass ratio, the positive electrode active material (Na4Fe3(PO4)2P2O7), binder (polyvinylidene fluoride (PVDF)), activated carbon, and sodium supplement (code H-3) were compounded in a ratio of 95:2.5:1.25:1.25 to obtain the positive electrode material. After adding it to the solvent N-methylpyrrolidone (NMP) and stirring until homogeneous, the positive electrode slurry was uniformly coated onto aluminum foil, with a single-sided coating weight of 0.3 g / 1540.25 mm. 2 After drying, cold pressing to a density of 3.0 g / cc, winding, assembly, and formation processes, a positive electrode sheet is formed. See Tables 1 and 2 for detailed parameters.

[0242] [Performance Testing]:

[0243] Performance tests of each embodiment and comparative sample:

[0244] 1. Test for residual sodium supplement in the battery:

[0245] The prepared electrode was cleaned, soaked in dimethyl carbonate (DMC) solution for 2 hours, and then dried to ensure the introduction of sodium into the electrolyte. The testing steps are as follows:

[0246] (1) Take an appropriate electrode sheet and scrape 2g of sample with a ceramic knife;

[0247] (2) Then pour it into a clean beaker, weigh out 100g of deionized water, and soak for 24 hours to ensure that the water-soluble sodium supplement dissolves in the water.

[0248] (3) Filter the clear liquid and take 1g of the clear liquid;

[0249] (4) Then, referring to the inductively coupled plasma atomic emission spectrometry (ICP-OES) EPA 6010D-2018 standard test, the Na element content was obtained, in units of X%.

[0250] (5) Adding the dilution factor of 100, the amount of Na is 100*X% = X g; this is only the content of sodium, so the content of sodium supplement is X*M / 23g (where M is the molar mass of sodium supplement and 23 is the molar mass of sodium); finally, divide by the initial sample of 2g, so the content of sodium supplement is 100X*M / 46%.

[0251] 2. Capacity Test

[0252] The specific capacity of the active material (positive electrode active material + sodium supplement) in the positive electrode sheet = battery capacity Cn / total weight M of the active material in the positive electrode sheet; (unit, mAh / g).

[0253] The method for testing the total weight M of active material in the positive electrode sheet is as follows:

[0254] (1) Weight M1 of the substrate disc: 1540.25mm of substrate (the current collector remaining after scraping off the positive electrode film). 2 Use small circular pieces to measure 10 samples, and record the average value as M1.

[0255] (2) Weight M2 of the small circular electrode sheet after cold pressing: 1540.25mm 2 The small circular pieces were used, and the average value of 10 samples was recorded as M2.

[0256] (3) The weight of the small disc positive electrode material M3: (M2-M1)*95%, of which 95% (the sodium supplement needs to be deducted in the examples or comparative examples containing sodium supplement) is the mass percentage of the battery.

[0257] (4) The total weight of active material in the positive electrode M = M3*A*B / 1540.25, where A and B represent the width and length of the cathode electrode in a single cell, respectively.

[0258] The battery capacity testing method is as follows:

[0259] The rated capacity, or battery capacity, is obtained by testing according to the rated capacity method in section 3.3 of GB / T 31486-2015 "Electrical Performance Requirements and Test Methods for Power Batteries for Electric Vehicles".

[0260] The battery capacity Cn testing procedure is as follows:

[0261] (1) Let the prepared battery cell stand at 25℃ for 30 min; (2) Then discharge it at a constant current rate of 1 / 3C to 2V; (3) Let it stand for 30 min; (4) Charge it at a constant current rate of 1 / 3C to 3.8V, and then charge it at a constant voltage rate to 0.05C cutoff; (5) Let it stand for 30 min; (6) Discharge it at a constant current rate of 1 / 3C to 2V; (7) Let it stand for 30 min. Repeat steps (4)-(7) for a total of 3 times, and take the capacity value measured on the third time as the battery capacity Cn.

[0262] 3. Battery cycle performance test

[0263] The battery cycle performance test procedure is as follows:

[0264] (1) Let the prepared battery cell stand at 25℃ for 30 min; (2) Charge it to 3.8V with 1 / 3Cn (the third capacity value measured in the aforementioned battery capacity test method), and then charge it at a constant voltage to 0.05C cutoff; (3) Let it stand for 30 min; (4) Discharge it to 2V with a constant current of 1 / 3Cn; (5) Let it stand for 10 min; (6) Discharge it to 2V with a constant current of 0.04Cn; (7) Let it stand for 30 min; (8) (9) Charge to 3.8V with 1 / 3Cn, then charge at a constant voltage to 0.05C (cut-off); (10) Let stand for 10 minutes; (11) Discharge to 2V with a constant current of 1Cn; (12) Let stand for 10 minutes; this is one cycle, and the capacity is recorded as Cn0; (13) Repeat steps (8)-(11) 99 times to obtain a total capacity of 100 cycles; (14) Repeat steps (1)-(12) 5 times; this is a capacity of 500 cycles Cn. 500 .

[0265] Calculate the capacity retention rate over 500 laps:

[0266] 500-cycle capacity retention rate (%) = Cn 500 / Cn0.

[0267] 4. The test methods for the performance of the positive electrode slurry are as follows:

[0268] Filtration performance:

[0269] like Figure 8 As shown: 1) First, determine that the filter screen is 150 mesh, then cut the filter screen into 25cm*25cm pieces with scissors. For example... Figure 8 Figure number (1) is shown in the middle;

[0270] 2) Find a clean 500ml beaker, and make sure the beaker is clean. For example... Figure 8 Figure number (2) is shown in the middle section;

[0271] 3) Fold the 150-mesh filter into a triangle. (Example:) Figure 8 Figure number (3) is shown in the middle section;

[0272] 4) Pour 500mL of slurry through the filter screen and record the time. (Example:) Figure 8 Figures numbered (4)-(6) are shown in the middle section;

[0273] 5) Record the filtration time for 300mL.

[0274] A filtration time exceeding 90 seconds indicates poor filtration performance and poor slurry processing performance.

[0275] The performance test results of each embodiment and comparative example are shown in Tables 3 and 4.

[0276] Table 1 Preparation parameters of composite sodium supplementation material

[0277]

[0278] Table 2 Product parameters of composite sodium supplement materials

[0279]

[0280]

[0281] Table 3. Positive Electrode Slurry Performance

[0282]

[0283] Table 4 Battery Performance Parameters

[0284]

[0285]

[0286] As can be seen from the data in the table above:

[0287] The filtration time of Comparative Example 2 is greater than 5 minutes; the filtration performance of the slurry is poor, far exceeding the standard requirement of less than 90 seconds. Therefore, the processing performance of the slurry is poor, making it difficult to apply on a large scale in industry.

[0288] Furthermore, compared with the various embodiments of this application, the specific capacity and cycle performance of Comparative Example 1 are significantly lower than those of the various embodiments of this application.

[0289] This demonstrates that the solution in this application embodiment can effectively improve the specific capacity and cycle performance; at the same time, the slurry has excellent processing performance, which is conducive to large-scale industrial application.

[0290] The embodiments described above are some, but not all, of the embodiments of this application. The detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

Claims

1. A battery cell, characterized in that, include: A positive electrode sheet, wherein the positive electrode sheet includes a positive electrode film layer; the positive electrode film layer includes a positive electrode active material and a porous conductive agent; The porous conductive agent contains a sodium supplement within its pores.

2. The battery cell according to claim 1, characterized in that, When the discharge capacity of the battery cell reaches more than 95% of the nominal capacity when discharged at 0.33C, the content of the sodium supplement in the positive electrode film layer is 0.01% to 0.05% by mass percentage.

3. The battery cell according to claim 1 or 2, characterized in that, The porous conductive agent satisfies at least one of the following characteristics: (1) The D of the porous conductive agent V 50 ranges from 1.2 μm to 10.4 μm; (2) The porous conductive agent of (D) V 90-D V 10) / D V 50 is 0.83 to 3.01; (3) The average pore size of the porous conductive agent is 2 nm to 50 nm.

4. The battery cell according to claim 1 or 2, characterized in that, The porous conductive agent includes: porous carbon material.

5. The battery cell according to any one of claims 1-3, characterized in that, The sodium supplement includes water-soluble sodium supplements.

6. The battery cell according to claim 5, characterized in that, The sodium supplement includes a weak acid-strong base salt of sodium; Optionally, the sodium supplement includes at least one of sodium nitrite, sodium citrate, sodium oxalate, or sodium carbonate.

7. The battery cell according to any one of claims 1-6, characterized in that, The sodium supplement includes Na2NiO2, Na2S, NaN3, Na2CO3, Na2C4O4, and C. 10 H 12 At least one of N2Na4O8, Na2C6H2O6, NaNO2, Na2S2O3, Na2SO3, or Na2S2O5.

8. The battery cell according to any one of claims 1-7, characterized in that, The decomposition voltage of the sodium supplement is 3.3V to 4.3V.

9. The battery cell according to any one of claims 1-8, characterized in that, The positive electrode active material includes at least one of polyanionic materials or layered oxides.

10. The battery cell according to claim 9, characterized in that, The positive electrode active material includes at least one of the following: sodium iron pyrophosphate, sodium iron pyrophosphate, sodium iron sulfate, sodium vanadium phosphate, and sodium fluorophosphate.

11. A composite sodium supplement material, characterized in that, include: A porous conductive agent and a sodium supplement agent, wherein the pores of the porous conductive agent contain the sodium supplement agent.

12. The composite sodium supplement material according to claim 11, characterized in that, The porous conductive agent satisfies at least one of the following characteristics: (1) The D of the porous conductive agent V 50 ranges from 1.2 μm to 10.4 μm; (2) The porous conductive agent of (D) V 90-D V 10) / D V 50 ranges from 0.83 to 3.01; (3) The average pore size of the porous conductive agent is 2nm-50nm.

13. The composite sodium-supplementing material according to claim 11 or 12, characterized in that, The pore volume of the composite sodium supplement material is 0.007 ml / g to 0.14 ml / g.

14. The composite sodium supplement material according to any one of claims 11-13, characterized in that, The sodium supplement includes water-soluble sodium supplements.

15. The composite sodium supplement material according to any one of claims 11-14, characterized in that, The sodium supplement includes Na2NiO2, Na2S, NaN3, Na2CO3, Na2C4O4, and C. 10 H 12 At least one of N2Na4O8, Na2C6H2O6, NaNO2, Na2S2O3, Na2SO3, or Na2S2O5.

16. The composite sodium supplement material according to any one of claims 11-15, characterized in that, The decomposition voltage of the sodium supplement is 3.3V to 4.3V.

17. A method for preparing a composite sodium supplement material, characterized in that, include: The mixed solution of sodium supplement and porous conductive agent is recrystallized to precipitate the sodium supplement and enter the pores of the porous conductive agent.

18. The method for preparing the composite sodium supplement material according to claim 17, characterized in that, The recrystallization of the mixed solution of sodium supplement and porous conductive agent includes: A saturated solution of sodium supplement is mixed with a porous conductive agent to obtain the mixed solution; the mixed solution is then stirred and heated.

19. The method for preparing the composite sodium supplement material according to claim 17 or 18, characterized in that, The mass ratio of sodium supplement to the porous conductive agent is (0.29-2.9):1; Optionally, the porous conductive agent has a pore volume greater than or equal to 0.2 ml / g; alternatively, the porous conductive agent has a pore volume of 0.5 ml / g to 2.0 ml / g. Optionally, the D of the porous conductive agent V 50 is 1μm to 10μm; optionally, the D of the porous conductive agent V 50 is 6μm to 10μm; Optionally, the porous conductive agent has (D) V 90-D V 10) / D V 50 is 0.8 to 3; Optionally, the average pore size of the porous conductive agent is 2nm-50nm; Optionally, the sodium supplement includes Na2NiO2, Na2S, NaN3, Na2CO3, Na2C4O4, and C. 10 H 12 At least one of N2Na4O8, Na2C6H2O6, NaNO2, Na2S2O3, Na2SO3, or Na2S2O5.

20. A battery, characterized in that, The battery comprises the battery cell according to any one of claims 1-10.

21. An electrical appliance, characterized in that, The electrical device comprises a single battery cell as described in any one of claims 1-10; or the electrical device comprises a battery as described in claim 20.

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