METHODS FOR PROCESSING PASTE USING CATALYTIC ELECTRODES AND EQUIPMENT FOR PROCESSING PASTE USING CATALYTIC ELECTRODES

Abstract

The invention relates to a method and apparatus for processing cathode paste. The processing method comprises a storage and / or transport step of cathode paste at temperatures between 0°C and 18°C, the cathode paste consisting of porous carbon. The processing method effectively reduces foaming and gelation in the cathode paste, improving the cycle stability and storage performance of sodium secondary batteries.

Description

Negative electrode slurry processing method and negative electrode slurry processing device

[0001] Cross-references

[0002] This application claims priority to Chinese Patent Application No. 202311470246.0, filed on November 7, 2023, entitled “Method for Processing Negative Electrode Slurry and Device for Processing Negative Electrode Slurry,” which is incorporated herein by reference in its entirety. Technical Field

[0003] The present application relates to the technical field of sodium batteries, and in particular to a method and device for processing negative electrode slurry. Background Art

[0004] In recent years, secondary batteries have been widely used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields.

[0005] Compared to lithium-ion batteries, sodium-ion batteries offer a significant competitive advantage due to their abundant and widespread sodium resources. However, sodium-ion batteries have certain drawbacks in their manufacturing, storage, and transportation processes, such as foaming in the negative electrode slurry. This has prevented mass production of these batteries to meet market demand.

[0006] Summary of the Invention

[0007] The present application is made in view of the above-mentioned problems, and its purpose is to provide a method for treating negative electrode slurry, aiming to improve the foaming and gelation phenomena of negative electrode slurry, so as to enhance the cycle stability and storage performance of sodium secondary batteries.

[0008] In a first aspect of the present application, a method for processing negative electrode slurry is provided, comprising: storing and / or transporting the negative electrode slurry at a temperature of 0° C. to 18° C., wherein the negative electrode slurry comprises porous carbon.

[0009] Controlling the storage and / or transportation temperature of the negative electrode slurry to be between 0°C and 18°C ​​increases the hydrogen bonding between water molecules in the solvent, which is beneficial to increasing the surface tension of the negative electrode slurry and the adsorption capacity of the surface of the negative electrode active material particles in the negative electrode slurry for water molecules, that is, the interaction force between water molecules in the negative electrode slurry and the adsorption force between the surface of the negative electrode active material particles on water molecules are both greater than the adsorption force of the porous carbon pores on water molecules, thereby reducing the probability of water molecules entering the pores of the negative electrode active material, reducing the generation of bubbles in the negative electrode slurry, improving the gelation and foaming of the negative electrode slurry, improving the stability of the negative electrode slurry, reducing the degree of leakage of the negative electrode slurry during the coating process, and improving the cycle stability and storage performance of the sodium secondary battery.

[0010] In any embodiment, the negative electrode slurry is stored and / or transported at a temperature of 3°C to 10°C, and optionally stored and / or transported at a temperature of 3°C to 6°C.

[0011] Further controlling the storage and / or transportation temperature of the negative electrode slurry to 3°C to 10°C or 3°C to 6°C is beneficial for further increasing the surface tension of the negative electrode slurry and the adsorption capacity of the surface of the negative electrode active material particles in the negative electrode slurry for water molecules, improving the foaming phenomenon of the negative electrode slurry, enhancing the stability of the negative electrode slurry, and improving the cycling performance and storage performance of the sodium secondary battery. In addition, it can also further reduce the cost increase caused by excessively low temperature.

[0012] In any embodiment, the negative electrode slurry is stored or transported at a stirring speed not exceeding 25 rpm.

[0013] The stirring speed of the negative electrode slurry during storage and / or transportation is controlled to not exceed 25 rpm, that is, the negative electrode slurry can be in a static state or in a slow stirring state, both of which can achieve the effect of improving the gel and foaming phenomenon of the negative electrode slurry. Compared with the negative electrode slurry in a slow stirring state, the stirring speed in the container is 0 rpm, which can significantly reduce production costs. Compared with the negative electrode slurry in a static state, slow stirring at a low speed can hinder the sedimentation of the negative electrode slurry, further improve the storage or transportation quality of the negative electrode slurry, and enhance the cycle performance and storage performance of its sodium secondary battery.

[0014] In any embodiment, the porous carbon comprises hard carbon.

[0015] In any embodiment, the solid content of the negative electrode slurry is 45% to 55%, and optionally 48% to 53%.

[0016] Controlling the solid content of the negative electrode slurry within an appropriate range is beneficial to the subsequent coating of the negative electrode slurry. Further controlling the solid content of the negative electrode slurry to 48% to 53% can take into account the storage, transportation and coating of the negative electrode slurry.

[0017] In any embodiment, after the negative electrode slurry is treated by the treatment method for 48 hours, the bubble volume per unit mass of the porous carbon does not exceed 4 mL.

[0018] After the negative electrode slurry is treated by the treatment method for 48 hours, the bubble volume per unit mass of porous carbon does not exceed 4 mL, which can effectively improve the foaming phenomenon of the negative electrode slurry and enhance the cycle stability and storage performance of its sodium secondary battery.

[0019] In any embodiment, the viscosity of the negative electrode slurry after being treated for 48 hours changes from 10,000 mPa·s to 30,000 mPa·s.

[0020] The viscosity of the negative electrode slurry changes to 10000 mPa·s to 30000 mPa·s after 48 hours of treatment, so that the negative electrode slurry still has fluidity after long-term storage or transportation, and improves the gelation phenomenon of the negative electrode slurry to facilitate subsequent coating.

[0021] In any embodiment, the processing method specifically includes: preparing negative electrode slurry, storing the negative electrode slurry in a slurry storage tank and / or transporting the negative electrode slurry in a pipeline.

[0022] In any embodiment, the maximum stirring speed for preparing the negative electrode slurry is 800 rpm to 1800 rpm, and can be optionally 1000 rpm to 1500 rpm.

[0023] In any embodiment, the temperature for preparing the negative electrode slurry is 5°C to 35°C, and can be optionally 5°C to 15°C.

[0024] Controlling the stirring speed and temperature in the process of preparing the negative electrode slurry within an appropriate range is beneficial to reducing the gel and foaming phenomenon of the negative electrode slurry after treatment, and improving the cycle stability and storage performance of the battery.

[0025] A second aspect of the present application provides a device for treating negative electrode slurry, the device comprising:

[0026] a cavity for accommodating negative electrode slurry, wherein the negative electrode slurry includes porous carbon;

[0027] The cooling device is used to cool the cavity so that the temperature of the cavity is 0°C to 18°C.

[0028] The device equipped with a cooling device can control the temperature of the cavity, thereby improving the gelation and foaming of the negative electrode slurry, and improving the cycle stability and storage performance of its sodium secondary battery.

[0029] In any embodiment, the device includes at least one of a slurry storage tank and a transportation pipeline.

[0030] The negative electrode slurry can be placed in a slurry storage tank for storage, or placed in a transportation pipeline for transportation. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1a) is a schematic structural diagram of a slurry storage tank in one embodiment of the present application;

[0032] Figure 1b) is a schematic structural diagram of a transport pipeline in one embodiment of the present application;

[0033] FIG2 is a schematic diagram showing the classification of gel state test results of negative electrode slurry after storage and / or transportation at 25° C. for 48 hours in one embodiment of the present application;

[0034] FIG3 is a schematic diagram of a sodium secondary battery according to an embodiment of the present application;

[0035] FIG4 is an exploded view of the sodium secondary battery according to one embodiment of the present application shown in FIG3 ;

[0036] FIG5 is a schematic diagram of a battery module according to an embodiment of the present application;

[0037] FIG6 is a schematic diagram of a battery pack according to an embodiment of the present application;

[0038] FIG7 is an exploded view of the battery pack shown in FIG6 according to an embodiment of the present application;

[0039] FIG8 is a schematic diagram of an electric device using a sodium secondary battery as a power source according to an embodiment of the present application.

[0040] Explanation of the reference numerals: 61 slurry storage tank; 601 condensate water inlet of the slurry storage tank; 602 condensate water outlet of the slurry storage tank; 71 transport pipeline; 701 condensate water inlet of the transport pipeline; 702 condensate water outlet of the transport pipeline; 1 battery pack; 2 upper box; 3 lower box; 4 battery module; 5 sodium secondary battery; 51 shell; 52 electrode assembly; 53 top cover assembly. DETAILED DESCRIPTION

[0041] Below, with appropriate reference to the accompanying drawings, embodiments of the negative electrode slurry processing method and apparatus of the present application are described in detail. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of substantially identical structures may be omitted. This is to avoid unnecessary length in the following description and to facilitate understanding by those skilled in the art. In addition, the drawings and the following description are provided to enable those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0042] " range " disclosed in the present application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0043] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0044] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0045] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0046] Unless otherwise specified, the terms "include" and "comprising" used in this application may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0047] Unless otherwise specified, the term "or" is used in this application to be inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied if any of the following conditions are met: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0048] Compared to traditional graphite, porous carbon, especially graphite, is often selected as one of the commonly used negative electrode active materials for sodium secondary batteries due to its higher capacity and rate performance. Traditional graphite systems, due to wetting, result in the presence of a solid-liquid interface. Residual gas causes foaming in the negative electrode slurry. The presence of surfactants in the negative electrode slurry also leads to air ingress during stirring, further exacerbating the foaming. Foaming is usually improved by adding low-surface-tension surfactants such as wetting agents or defoamers. However, due to the pores in porous carbon, during the preparation, storage, and transportation of the negative electrode slurry, solvent water molecules in the negative electrode slurry will slowly enter the pores of the porous carbon, expelling the gas adsorbed in the porous carbon pores and causing foaming in the negative electrode slurry. The foaming is particularly severe during storage and transportation. Introducing low-surface-tension surfactants into the negative electrode slurry further encourages solvent water molecules to enter the porous carbon pores, exacerbating the foaming. Foaming of the negative electrode slurry is detrimental to subsequent coating. It also causes gelation problems, making coating more difficult and significantly impacting the mass production and performance of sodium secondary batteries. Therefore, it is necessary to design a negative electrode slurry treatment method to improve the foaming and gelation of the negative electrode slurry, thereby ensuring that the product meets market demand.

[0049] [Negative electrode slurry processing method]

[0050] Based on this, the present application proposes a method for processing negative electrode slurry, comprising: storing and / or transporting the negative electrode slurry at a temperature of 0°C to 18°C, wherein the negative electrode slurry comprises porous carbon.

[0051] Porous carbon materials refer to carbon materials with pore structures of varying sizes, possessing highly developed specific surface areas and pore structures. Pore sizes range from ultrafine nanopores the size of molecules to micropores suitable for microbial activity. According to the International Union of Pure and Applied Chemistry (IUPAC), porous carbon materials can be classified into three categories based on pore size: microporous (<2 nm), mesoporous (2-50 nm), and macroporous (>50 nm). In some embodiments, porous carbon comprises hard carbon.

[0052] In some embodiments, the temperature for storage and / or transportation of the negative electrode slurry may be selected from 0°C, 1°C, 2°C, 3°C, 4°C, 5°C, 6°C, 7°C, 8°C, 9°C, 10°C, 12°C, 14°C, 15°C, 16°C, 18°C ​​or a value in a range consisting of any two of the above points.

[0053] Research has found that the sodium storage mechanism of porous carbon, especially hard carbon, can be simply summarized as: 1) adsorption on the surface, defect sites and functional groups; 2) filling of micropores; 3) intercalation of graphitized carbon layers. Based on the above sodium storage mechanism, the gram capacity can be increased by increasing the porosity and optimizing the pore structure. However, with the increase of porosity, during the preparation, storage and transportation of the negative electrode slurry using porous carbon as the negative electrode active material, the solvent water molecules will gradually enter the porous carbon pores, expelling the gas adsorbed in the porous carbon pores, resulting in a large number of bubbles in the negative electrode slurry, which worsens the stability of the negative electrode slurry. The foaming phenomenon of the negative electrode slurry will cause the negative electrode slurry to have a coating leak problem during the coating process, which will affect the distribution of the active material of the electrode, resulting in fluctuations in the CB value and a serious risk of sodium precipitation.

[0054] It can be understood that controlling the storage and / or transportation temperature of the negative electrode slurry to be 0°C to 18°C ​​increases the hydrogen bonding effect between the water molecules in the solvent, which is beneficial to increasing the surface tension of the negative electrode slurry and the adsorption capacity of the surface of the negative electrode active material particles in the negative electrode slurry for water molecules, that is, the interaction force between the water molecules in the negative electrode slurry and the adsorption force between the surface of the negative electrode active material particles on the water molecules are greater than the adsorption force of the porous carbon pores on water molecules, thereby reducing the probability of water molecules entering the pores of the negative electrode active material, reducing the generation of bubbles in the negative electrode slurry, improving the gelation and foaming of the negative electrode slurry, improving the stability of the negative electrode slurry, reducing the degree of leakage of the negative electrode slurry during the coating process, and improving the cycle stability and storage performance of the sodium secondary battery.

[0055] Herein, "the temperature of the negative electrode slurry during storage and / or transportation is 0° C. to 18° C." can be detected by any temperature detection device, such as a temperature sensor.

[0056] In some embodiments, the negative electrode slurry is stored and / or transported at a temperature of 3°C to 10°C. In some embodiments, the negative electrode slurry is stored and / or transported at a temperature of 3°C to 6°C. In some embodiments, the temperature for storing and / or transporting the negative electrode slurry can be selected from 3°C, 4°C, 5°C, 6°C, 7°C, 8°C, 9°C, 10°C, or a value in a range consisting of any two of the above.

[0057] Further controlling the storage and / or transportation temperature of the negative electrode slurry to 3°C to 10°C or 3°C to 6°C is beneficial for further increasing the surface tension of the negative electrode slurry and the adsorption capacity of the negative electrode active material particles in the negative electrode slurry for water molecules, improving the gelation and foaming of the negative electrode slurry, improving the stability of the negative electrode slurry, and improving the cycle stability and storage performance of the sodium secondary battery. In addition, it can further reduce the cost increase caused by excessively low temperature.

[0058] In some embodiments, the negative electrode slurry is stored and / or transported at a stirring speed of no more than 25 rpm.

[0059] In some embodiments, the stirring speed for storage and / or transportation of the negative electrode slurry may be selected as 0 rpm, 0.1 rpm, 0.5 rpm, 1 rpm, 3 rpm, 5 rpm, 7 rpm, 9 rpm, 10 rpm, 13 rpm, 15 rpm, 20 rpm, 25 rpm, or a value in a range consisting of any two of the above points.

[0060] The stirring speed of the negative electrode slurry during storage and / or transportation is controlled not to exceed 25 rpm, that is, the negative electrode slurry in the container can be in a static state or in a low-speed slow stirring state, both of which can achieve the effect of improving the gelation and foaming of the negative electrode slurry.

[0061] In some embodiments, the stirring speed of the negative electrode slurry during storage and / or transportation is 0 rpm-15 rpm.

[0062] A stirring speed of 0 rpm can significantly reduce production costs. Compared to leaving the negative electrode slurry in a static state, slow stirring can prevent the slurry from settling while preventing low viscosity and excessive water from entering the porous carbon pores. This can further improve the storage or transportation quality of the negative electrode slurry and enhance the cycling and storage performance of its sodium secondary battery.

[0063] In some embodiments, the porous carbon comprises hard carbon.

[0064] In some embodiments, the solid content of the negative electrode slurry is 45% to 55%. In some embodiments, the solid content of the negative electrode slurry is 48% to 53%.

[0065] In some embodiments, the solid content of the negative electrode slurry may be 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55% or a value in a range consisting of any two of the above points.

[0066] Controlling the solid content of the negative electrode slurry within an appropriate range is beneficial to the subsequent coating of the negative electrode slurry. Further controlling the solid content of the negative electrode slurry to 48% to 53% can take into account the storage, transportation and coating of the negative electrode slurry.

[0067] In some embodiments, after the negative electrode slurry is treated by the treatment method for 48 hours, the bubble volume per unit mass of the porous carbon does not exceed 4 mL / g.

[0068] In this application, the bubble volume per unit mass of porous carbon in the negative electrode slurry can be tested using methods known in the art. For example, the negative electrode slurry (the mass of porous carbon in the negative electrode slurry is m, in g) is sealed in a sealed bag and the gas change is tested using the water displacement method. The initial volume is V0, in mL, and the test volume after 48 hours is V1, in mL. The bubble volume per unit mass of porous carbon = (V1-V0) / m, in mL / g.

[0069] In some embodiments, after the negative electrode slurry is treated by the treatment method for 48 hours, the bubble volume per unit mass of the porous carbon is 0 mL / g, 1 mL / g, 2 mL / g, 3 mL / g, 4 mL / g, or a value in a range consisting of any two of the above points.

[0070] The bubble volume per unit mass of porous carbon in the negative electrode slurry does not exceed 4 mL / g, which can effectively improve the foaming phenomenon of the negative electrode slurry and enhance the cycle stability and storage performance of its sodium secondary battery.

[0071] In some embodiments, the viscosity of the negative electrode slurry after being treated by the method for 48 hours changes from 10,000 mPa·s to 30,000 mPa·s.

[0072] In this application, the viscosity change of the negative electrode slurry after 48 hours of the treatment method can be tested by methods known in the art, such as using a rotary viscometer to measure the initial viscosity of the negative electrode slurry before treatment. Select a suitable rotor, fix the viscometer rotor, place the negative electrode slurry under the viscometer rotor, and just submerge the scale line of the rotor. Instrument model: Shanghai Fangrui NDJ-5S, rotor: 63# (2000-10000mPa.s), 64# (10000-50000mPa.s), speed: 12 rpm, test temperature: 25°C, test time: 5 minutes, and read the data after the display stabilizes.

[0073] After 48 hours of storage and / or transportation, the negative electrode slurry is retested for viscosity. The viscosity of the negative electrode slurry is measured using a rotating viscometer. Select a suitable rotor, secure the viscometer rotor, and place the negative electrode slurry under the viscometer rotor so that the negative electrode slurry just covers the scale line of the rotor. Instrument model: Shanghai Fangrui NDJ-5S, rotor: 63# (2000-10000mPa.s), 64# (10000-50000mPa.s), speed: 12 rpm, test temperature: 25°C, test time: 5 minutes, and read the data after the display stabilizes. The viscosity change of the negative electrode after 48 hours of storage and / or transportation is the difference between the viscosity of the negative electrode slurry after 48 hours of storage and / or transportation and the initial viscosity of the negative electrode slurry.

[0074] In some embodiments, the viscosity of the negative electrode slurry after being placed at 25° C. for 48 hours changes to 10,000 mPa·s, 15,000 mPa·s, 20,000 mPa·s, 25,000 mPa·s, 30,000 mPa·s, or a value in a range consisting of any two of the above points.

[0075] The viscosity of the negative electrode slurry changes to 10,000 mPa·s to 30,000 mPa·s after 48 hours of treatment, which allows the negative electrode slurry to still have fluidity after long-term storage or transportation, improves the gelation phenomenon of the negative electrode slurry, and facilitates subsequent coating.

[0076] In some embodiments, the processing method specifically includes: preparing the negative electrode slurry, storing the negative electrode slurry in a slurry storage tank and / or transporting the negative electrode slurry in a pipeline.

[0077] In some embodiments, the maximum stirring speed for preparing the negative electrode slurry is 800 rpm to 1800 rpm. In some embodiments, the maximum stirring speed for preparing the negative electrode slurry is 1000 rpm to 1500 rpm.

[0078] In some embodiments, the stirring speed for preparing the negative electrode slurry is 800 rpm, 900 rpm, 1000 rpm, 1100 rpm, 1200 rpm, 1300 rpm, 1400 rpm, 1500 rpm, 1600 rpm, 1700 rpm, 1800 rpm, or a value in a range consisting of any two of the foregoing.

[0079] The stirring speed of the negative electrode slurry is controlled within an appropriate range to prepare a negative electrode slurry with uniform distribution of solid particles, improve the stability of the negative electrode slurry, reduce the gel and foaming phenomenon of the negative electrode slurry after treatment, and improve the cycle stability and storage performance of the battery.

[0080] In some embodiments, the temperature for preparing the negative electrode slurry is 5° C. to 35° C. In some embodiments, the temperature for preparing the negative electrode slurry is 5° C. to 15° C. In some embodiments, the temperature for preparing the negative electrode slurry can be selected from 5° C., 10° C., 15° C., 20° C., 25° C., 30° C., 35° C., or a value in a range consisting of any two of the foregoing values.

[0081] During the preparation process, the temperature of the negative electrode slurry is controlled within an appropriate range to reduce the gelation and foaming of the negative electrode slurry after treatment, thereby improving the cycle stability and storage performance of the battery.

[0082] In some embodiments, preparing the negative electrode slurry further comprises:

[0083] At a temperature of 5° C. to 35° C., raw materials including a negative electrode active material, a conductive agent, a binder, and a dispersant are mixed and stirred to prepare a negative electrode slurry; in some embodiments, the raw materials further include a plasticizer.

[0084] In some embodiments, the negative electrode active material includes hard carbon.

[0085] In some embodiments, the conductive agent includes one or more of SuperP, Ketjen black, acetylene black, carbon nanotubes, and graphene. In some embodiments, the conductive agent includes SuperP.

[0086] In some embodiments, the binder comprises one or more of styrene-butadiene rubber, polyacrylic acid, polyacrylate, polyamide, poly(acrylonitrile-acrylate), poly(styrene-acrylate). In some embodiments, the binder comprises styrene-butadiene rubber.

[0087] In some embodiments, the dispersant comprises sodium carboxymethylcellulose.

[0088] In some embodiments, the plasticizer includes 1,3,-butanediol.

[0089] The above-mentioned dispersant is beneficial to improving the dispersion uniformity of the negative electrode slurry and improving the processability of the negative electrode slurry. The above-mentioned conductive agent and binder can make the negative electrode sheet prepared by the negative electrode slurry have excellent conductivity and adhesion. The above-mentioned plasticizer can make the negative electrode sheet prepared by the negative electrode slurry have excellent toughness and reduce the cracking of the negative electrode sheet.

[0090] [Device for processing negative electrode slurry]

[0091] In some embodiments, the present application further provides a device for treating negative electrode slurry, the device comprising:

[0092] a cavity for accommodating negative electrode slurry, wherein the negative electrode slurry includes porous carbon;

[0093] The cooling device is used to cool the cavity so that the temperature in the container is 0°C to 18°C.

[0094] The device equipped with a cooling device can control the temperature of the cavity, thereby improving the gelation and foaming of the negative electrode slurry, and improving the cycle stability and storage performance of its sodium secondary battery.

[0095] In some embodiments, the device further comprises a temperature detection device for monitoring the temperature of the cooling device and / or the temperature in the device.

[0096] In some embodiments, the temperature detection device is a temperature sensor.

[0097] The temperature detection device can control the temperature of the cavity to 0℃~18℃, thereby improving the gelation and foaming of the negative electrode slurry and enhancing the cycle stability and storage performance of its sodium secondary battery.

[0098] In some embodiments, the device includes at least one of a slurry storage tank and a transportation pipeline.

[0099] As shown in Figure 1a) and Figure 1b), the slurry storage tank 61 or the transport pipeline 71 includes a cooling device. For example, the cooling device is equipped with condensed water. For the slurry storage tank 61, the condensed water enters from the condensed water inlet 601 of the slurry storage tank and exits from the condensed water outlet 602 of the slurry storage tank, or, for the transport pipeline 71, the condensed water enters from the condensed water inlet 701 of the transport pipeline and exits from the condensed water outlet 702 of the transport pipeline, which can effectively reduce the temperature in the container cavity so that the temperature in the container reaches 0°C to 18°C.

[0100] The negative electrode slurry can be placed in a slurry storage tank for storage, or placed in a transportation pipeline for transportation.

[0101] In some embodiments, the cooling device comprises a pipe filled with a cooling medium; the cooling medium comprises at least one of water, liquid nitrogen, and dry ice.

[0102] The above cooling media can reduce the temperature in the container cavity so that the temperature in the container cavity is 0°C to 18°C.

[0103] [Negative electrode]

[0104] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer located on at least one side of the negative electrode current collector, and the negative electrode film layer includes a negative electrode active material.

[0105] As an example, the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0106] 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 base layer and a metal layer formed on at least one surface of the polymer base material. 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 base material (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0107] In some embodiments, the negative electrode film layer is prepared from the negative electrode slurry processed by the negative electrode slurry processing method in some embodiments.

[0108] In some embodiments, the negative electrode film layer may further include a binder. For example, 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).

[0109] In some embodiments, the negative electrode film layer may further include a conductive agent. For example, 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.

[0110] In some embodiments, the negative electrode film layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0111] The negative electrode sheet can be prepared in the following manner: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0112] [Positive electrode]

[0113] The positive electrode sheet includes a positive electrode current collector and a positive electrode film layer located on at least one side of the positive electrode current collector, and the positive electrode film layer includes a positive electrode active material.

[0114] As an example, the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive electrode current collector.

[0115] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, aluminum foil may be used. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector may be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0116] In some embodiments, the positive electrode active material may be a positive electrode active material for batteries well-known in the art. As an example, the positive electrode active material may include at least one of the following materials: layered transition metal oxides, polyanion compounds, or Prussian blue compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Among them, the Prussian blue compound includes Na x P[R(CN)6] δ ·zH2O, where P and R are each independently selected from at least one of transition metal elements, 0 < x ≤ 2, 0 < δ ≤ 1, and 0 ≤ z ≤ 10; the polyanion compound includes Na b Me c (PO4) d O2X, where A includes one or more of H, Li, Na, K, and NH4, Me includes one or more of Ti, Cr, Mn, Fe, Co, Ni, V, Cu, and Zn, X includes one or more of F, Cl, and Br, 0 < b ≤ 4, 0 < c ≤ 2, 1 ≤ d ≤ 3; the layered transition metal oxide includes Na a M b Fe c O2, M includes transition metal ions, 0.67 < a < 1.1, 0.5 < b < 1, 0 < c < 0.5.

[0117] In some embodiments, the positive electrode film layer may also optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0118] In some embodiments, the positive electrode film layer may also optionally include a conductive agent. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0119] In some embodiments, the positive electrode sheet can be prepared by the following method: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0120] [Electrolytes]

[0121] The electrolyte conducts ions between the positive and negative electrodes. This application does not specify the type of electrolyte, and the electrolyte can be selected based on the needs. For example, the electrolyte can be liquid, gel, or solid.

[0122] In some embodiments, the electrolyte is an electrolyte solution comprising an electrolyte salt and a solvent.

[0123] In some embodiments, the electrolyte includes an electrolyte salt selected from at least one of NaPF6, NaBF4, NaN(SO2F)2(NaFSI), NaClO4, NaAsF6, NaB(C2O4)2(NaBOB), NaBF2(C2O4)(NaDFOB), NaN(SO2RF)2, and NaN(SO2F)(SO2RF), wherein RF is represented by C b F 2b+1 , b is an integer between 1 and 10, and can be optionally an integer between 1 and 3.

[0124] In some embodiments, the electrolyte salt is selected from one or more of NaPF6, NaN(SO2F)2, NaN(CF3SO2)2, NaB(C2O4)2, and NaBF2(C2O4). In some embodiments, the electrolyte salt is selected from one or more of NaPF6, NaN(SO2RF)2, and NaBF2(C2O4). In some embodiments, RF is -CF3, -C2F5, or -CF2CF2CF3.

[0125] In some embodiments, the electrolyte includes a solvent, and the solvent includes at least one of a chain carbonate, a chain carboxylate, a cyclic carbonic acid, an ether solvent, a sulfone solvent, and a nitrile solvent. In some embodiments, the chain carbonate includes at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), methyl propyl carbonate (MPC), methyl isopropyl carbonate (MIPC), methyl butyl carbonate, ethyl propyl carbonate, dipropyl carbonate, and dibutyl carbonate. In some embodiments, the chain carbonate includes at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and methyl propyl carbonate (MPC). In some embodiments, the chain carboxylate includes at least one of methyl formate (MF), ethyl formate (EF), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), ethyl butyrate (EB), methyl acetate (MA), ethyl acetate (EA), and propyl acetate (PA). In some embodiments, the linear carboxylic acid ester includes at least one of methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl acetate (MA), ethyl acetate (EA), and propyl acetate (PA). In some embodiments, the ether solvent includes at least one of dioxolane (DOL), tetrahydrofuran (THF), 2-methyltetrahydrofuran (2Me-THF), tetrahydropyran (THP), 1,2-dimethoxyethane (DME), diethylene glycol dimethyl ether (DG), 1,2-diethoxyethane, and 1,2-dibutoxyethane.

[0126] In some embodiments, the electrolyte may further include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, and additives that improve battery high or low temperature performance.

[0127] [Isolation film]

[0128] In some embodiments, the sodium secondary battery further includes a separator, which can be any known porous separator with good chemical and mechanical stability.

[0129] In some embodiments, the material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer can be the same or different.

[0130] In some embodiments, the isolation film further has at least one of a bonding coating and a ceramic coating.

[0131] [Sodium secondary battery]

[0132] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be formed into an electrode assembly through a winding process or a lamination process.

[0133] In some embodiments, the sodium secondary battery may include an outer packaging that can be used to encapsulate the electrode assembly and the electrolyte.

[0134] In some embodiments, the outer packaging of the sodium secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. Alternatively, the outer packaging of the sodium secondary battery can be a soft shell, such as a pouch-type soft shell. The soft shell can be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0135] The shape of the sodium secondary battery in this application can be cylindrical, square or any other shape. For example, FIG3 shows a sodium secondary battery 5 with a square structure as an example.

[0136] In some embodiments, referring to FIG4 , the outer packaging may include a shell 51 and a cover plate 53. The shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the separator can be formed into an electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the sodium secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.

[0137] In some embodiments, sodium secondary batteries can be assembled into a battery module. The number of sodium secondary batteries contained in the battery module can be one or more. The specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

[0138] Figure 5 illustrates an example battery module 4. Referring to Figure 5 , within the battery module 4, multiple sodium secondary batteries 5 may be arranged sequentially along the length of the module 4. Of course, any other arrangement is also possible. Furthermore, the multiple sodium secondary batteries 5 may be secured using fasteners.

[0139] Optionally, the battery module 4 may further include a housing having an accommodation space, and the plurality of sodium secondary batteries 5 are accommodated in the accommodation space.

[0140] In some embodiments, the battery modules described above may also be assembled into a battery pack. The battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art based on the application and capacity of the battery pack.

[0141] Figures 6 and 7 illustrate an example battery pack 1. Referring to Figures 6 and 7 , the battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box comprises an upper case 2 and a lower case 3. The upper case 2 can be positioned over the lower case 3 to form an enclosed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0142] In addition, the present application also provides an electrical device, which includes at least one of the sodium secondary battery, battery module, or battery pack provided in the present application. The sodium secondary battery, battery module, or battery pack can be used as a power source for the electrical device, and can also be used as an energy storage unit for the electrical device. The electrical device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as 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., but is not limited thereto.

[0143] As the electrical device, a sodium secondary battery, a battery module or a battery pack can be selected according to its usage requirements.

[0144] Figure 8 shows an example of an electric device. This device can be a pure electric vehicle, hybrid electric vehicle, or plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of sodium secondary batteries, a battery pack or battery module can be used.

[0145] Another example device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is generally required to be lightweight and thin, and may use a sodium secondary battery as a power source.

[0146] Example

[0147] Below, the embodiment of the present application is described. The embodiment described below is exemplary and is only used to explain the present application, and is not to be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0148] 1. Preparation method

[0149] Example 1

[0150] 1) Treatment of negative electrode slurry

[0151] Preparation process of negative electrode slurry: The mass ratio of negative electrode active material hard carbon: conductive agent Super P, dispersant sodium carboxymethyl cellulose (Nippon Paper, weight average molecular weight of 350,000), plasticizer 1,3-butanediol and binder styrene butadiene rubber (SBR) is 95:0.5:0.4:1.0:0.1:3.

[0152] The negative electrode active material hard carbon, the conductive agent Super P and sodium carboxymethyl cellulose with a weight average molecular weight of 80,000 were mixed at a stirring speed of 600 rpm for 40 minutes to obtain a dry mix;

[0153] The dry mix was mixed with solvent water and kneaded for 60 min to obtain an adhesive mixture with a solid content of 65%;

[0154] The adhesive mixture and sodium carboxymethyl cellulose with a weight average molecular weight of 400,000 were mixed, and solvent water was added and stirred evenly at a stirring speed of 1600 rpm for 45 minutes to obtain a first adhesive solution;

[0155] The first glue solution was mixed with the plasticizer 1,3-butanediol and stirred evenly, and then the binder styrene-butadiene rubber (SBR) was added and stirred continuously at a stirring speed of 700 rpm for 25 minutes to obtain a negative electrode slurry with a solid content of 50%;

[0156] The temperature of the above preparation process was controlled at 15°C.

[0157] Anode slurry treatment: The slurry was placed in a 5°C storage tank and then pumped to a 5°C transport pipeline for transportation. The storage time in the tank was 24 hours, and the transport time in the pipeline was 24 hours at a linear speed of 20 m / s. The bubble volume per unit mass of hard carbon in the treated anode slurry was 0 mL, and the viscosity change was 14223 mPa·s.

[0158] 2) Negative electrode

[0159] The negative electrode slurry after the above treatment was evenly coated on the negative electrode current collector copper foil with a thickness of 8 μm; the copper foil was dried at room temperature and then transferred to a 120°C oven for drying for 1 hour, and then cold pressed and cut to obtain the negative electrode sheet.

[0160] 3) Positive electrode

[0161] The positive electrode active material Na3V2(PO4)2O2F, the conductive agent acetylene black, and the binder polyvinylidene fluoride (PVDF) were fully stirred and mixed in an appropriate amount of N-methylpyrrolidone (NMP) at a weight ratio of 80:10:10 to form a uniform positive electrode slurry; the positive electrode slurry was mixed at a ratio of 0.28g (dry weight) / 1540.25mm 2The density is evenly coated on the positive electrode current collector aluminum foil with a thickness of 13μm, and the coating speed is 30m / min; the temperature of the coating oven is 110℃, and then the positive electrode sheets are obtained through cold pressing and slitting.

[0162] 4) Electrolyte

[0163] In an argon atmosphere glove box (H2O content <10ppm, O2 content <1ppm), propylene carbonate (PC) and ethyl methyl carbonate (EMC) were mixed in a mass ratio of 30 / 70, and 1M NaPF6 sodium salt was dissolved and stirred evenly to prepare an electrolyte.

[0164] 5) Isolation film

[0165] A 12 μm polyethylene (PE) porous polymer film was used as the separator.

[0166] 6) Preparation of batteries

[0167] The positive electrode sheet, the separator, and the negative electrode sheet are stacked in order, so that the separator is placed between the positive and negative electrode sheets to isolate the positive and negative electrode sheets. The bare battery cell is wound, the tabs are welded, and the bare battery cell is placed in an outer package. The above-prepared electrolyte is injected into the dried battery cell, and then the sodium secondary battery product of Example 1 is obtained after packaging, standing, formation, shaping, and capacity testing.

[0168] The preparation methods of the sodium secondary batteries of Examples 2-7 are basically the same as the preparation method of Example 1, except that the temperature of the slurry storage tank or the transportation pipeline is adjusted. Specific parameters are shown in Table 1.

[0169] The preparation methods of the sodium secondary batteries of Examples 8-10 are substantially the same as the preparation method of Example 1, except that the stirring speed of the slurry storage tank is adjusted. Specific parameters are shown in Table 1.

[0170] The preparation methods of the sodium secondary batteries of Examples 11 and 12 are basically the same as the preparation method of Example 1, except that the maximum stirring speed of the first glue solution in the negative electrode slurry preparation process is adjusted. The specific parameters are shown in Table 1.

[0171] The preparation methods of the sodium secondary batteries of Examples 13 and 14 are basically the same as the preparation method of Example 1, except that the temperature during the preparation of the negative electrode slurry is adjusted. Specific parameters are shown in Table 1.

[0172] The preparation method of the sodium secondary battery of Example 15 is basically the same as the preparation method of Example 1, except that the negative electrode slurry is only stored in the slurry storage tank and the storage time is 48 hours. Specific parameters are shown in Table 1.

[0173] The preparation method of the sodium secondary battery in Example 16 is basically the same as the preparation method in Example 1, except that the negative electrode slurry is only transported in the transport pipeline, and the transportation time is 48 hours. Specific parameters are shown in Table 1.

[0174] The preparation method of the sodium secondary battery of Comparative Example 1-2 is basically the same as the preparation method of Example 1, except that the temperature of the slurry storage tank and / or the transportation pipeline is adjusted. The specific parameters are shown in Table 1.

[0175] 2. Performance Testing

[0176] 1. Anode slurry

[0177] 1) Viscosity change test of negative electrode slurry after 24 hours and 48 hours of storage and / or transportation

[0178] Use a rotary viscometer to measure the initial viscosity of the negative electrode slurry before treatment: select a suitable rotor, fix the viscometer rotor, place the negative electrode slurry under the viscometer rotor, and the negative electrode slurry just submerges the scale line of the rotor. Instrument model: Shanghai Fangrui NDJ-5S, rotor: 63# (2000-10000mPa.s), 64# (10000-50000mPa.s), speed: 12 rpm, test temperature: 25℃, test time is 5 minutes, and read the data after the display is stable.

[0179] After 24 hours of storage and / or transportation, retest the viscosity of the negative electrode slurry using a rotating viscometer. Select a suitable rotor, secure the viscometer rotor, and place the negative electrode slurry under the viscometer rotor so that the negative electrode slurry just covers the scale line of the rotor. Instrument model: Shanghai Fangrui NDJ-5S, rotor: 63# (2000-10000mPa.s), 64# (10000-50000mPa.s), speed: 12 rpm, test temperature: 25°C, test time: 5 minutes, and read the data after the display stabilizes. The viscosity change of the negative electrode slurry after 24 hours of storage and / or transportation is the difference between the viscosity of the negative electrode slurry after 24 hours of storage and / or transportation and the initial viscosity of the negative electrode slurry.

[0180] After 48 hours of storage and / or transportation, the negative electrode slurry is retested for viscosity. The viscosity of the negative electrode slurry is measured using a rotating viscometer. Select a suitable rotor, fix the viscometer rotor, and place the negative electrode slurry under the viscometer rotor. The negative electrode slurry just covers the scale line of the rotor. Instrument model: Shanghai Fangrui NDJ-5S, rotor: 63# (2000-10000mPa.s), 64# (10000-50000mPa.s), speed: 12 rpm, test temperature: 25°C, test time: 5 minutes, and read the data after the display stabilizes. The viscosity change of the negative electrode slurry after 48 hours of storage and / or transportation is the difference between the viscosity of the negative electrode slurry after 48 hours of storage and / or transportation and the initial viscosity of the negative electrode slurry.

[0181] 2) Gel state test of negative electrode slurry after 48 hours of storage and / or transportation

[0182] After the negative electrode slurry has been stored and / or transported for 48 hours, take an appropriate amount of the negative electrode slurry and place it in a beaker. Use a steel ruler to lift the negative electrode slurry in the beaker and judge the gel state of the negative electrode slurry based on the flow state of the negative electrode slurry.

[0183] In the non-gel state, the negative electrode slurry flows naturally and continuously, and the negative electrode slurry flows flat on the surface of the steel ruler without agglomeration, as shown in FIG2a ;

[0184] In the slight gel state, the negative electrode slurry flows naturally and continuously, but the fluid is thin. The negative electrode slurry is basically spread evenly on the surface of the steel ruler, with slight small pieces, as shown in Figure 2b);

[0185] The moderate gel state is that the negative electrode slurry drips naturally and intermittently; it does not flow continuously, and the negative electrode slurry cannot be spread evenly on the surface of the steel ruler, with obvious block agglomerations, as shown in Figure 2c);

[0186] The severe gel state is that the negative electrode slurry cannot flow down in a stream, but falls into lumps or remains directly on the steel ruler and cannot flow down, as shown in Figure 2d).

[0187] 3) Bubble volume test in negative electrode slurry

[0188] After 48 hours of storage and / or transportation, seal the anode slurry (mass of hard carbon in the anode slurry is m, in g) in a sealed bag and measure the gas evolution using the displacement method. The initial volume is V0, in mL, and the measured volume after 48 hours is V1, in mL. The gas generation rate of the anode slurry is calculated as (V1 - V0) / m, in mL / g.

[0189] 2. Battery

[0190] 1) Cycle performance

[0191] At 25°C, the prepared battery was charged to 3.95V at a constant current of 1C, then charged at a constant voltage of 3.95V until the current dropped to 0.05C. After standing for 10 minutes, it was discharged to 1.5V at a constant current of 1C. This was one charge / discharge cycle of the battery. The capacity of the first discharge was 100%, and the charge and discharge cycle was repeated. When the discharge capacity decayed to 80%, the test was stopped and the number of cycles was recorded. The number of cycles when the capacity retention rate reached 80% was used as an indicator to evaluate the battery cycle performance.

[0192] 2) Storage performance

[0193] At 25°C, the prepared battery was charged at a constant current of 1C to 3.95V, then charged at a constant voltage of 3.95V until the current dropped to 0.05C. After standing for 10 minutes, it was discharged at a constant current of 1C to 1.5V. This was one charge / discharge cycle of the battery, with the capacity at the first discharge being 100%. The battery was then placed in a 60°C oven for a period of time, then taken out and the above charging steps were repeated. The discharge capacity was recorded until the discharge capacity decayed to 80%. The test was stopped and the storage days were recorded. The storage days until the capacity retention rate reached 80% were used as an indicator to evaluate the battery storage performance.

[0194] 3. Analysis of test results of various embodiments and comparative examples

[0195] Batteries of various examples and comparative examples were prepared according to the above methods, and various performance parameters were measured. The results are shown in Table 1 below.

[0196] Table 1

[0197] In Examples 1-16, the negative electrode slurry including hard carbon was stored and / or transported at a temperature between 0°C and 18°C. As shown in Examples 1-16, when the negative electrode slurry including hard carbon was stored and / or transported at a temperature between 0°C and 18°C, the gelation of the negative electrode slurry was improved, the foaming volume per unit mass of the hard carbon was small, and the battery had good cycling stability and storage performance.

[0198] From the comparison of the embodiments and the comparative examples, it can be seen that storing and / or transporting the negative electrode slurry at a temperature of 0°C to 18°C ​​can effectively improve the gelation of the slurry, reduce the bubble volume per unit mass of hard carbon, and enhance the cycle stability and storage performance of the battery.

[0199] As shown in Examples 1 and 8-10, when the stirring speed of the slurry storage tank does not exceed 25 rpm, the negative electrode slurry does not gel after storage and / or transportation at a temperature of 0°C to 18°C, the bubble volume per unit mass of hard carbon is small, and the battery has good cycle stability and storage performance. When the stirring speed of the slurry storage tank is 0 rpm to 15 rpm, the cycle stability and storage performance of the battery can be further improved.

[0200] It can be seen from Examples 1, 11, and 12 that when the maximum stirring speed for preparing the negative electrode slurry is 800 rpm to 1800 rpm, the negative electrode slurry does not gel after being stored and / or transported at a temperature of 0°C to 18°C, the bubble volume per unit mass of hard carbon is small, and the battery has good cycle stability and storage performance.

[0201] As can be seen from Examples 1, 14, and 15, when the temperature for preparing the negative electrode slurry is 5°C to 35°C, the negative electrode slurry does not gel after storage and / or transportation at a temperature of 0°C to 18°C, the bubble volume per unit mass of hard carbon is small, and the battery has good cycle stability and storage performance. When the temperature for preparing the negative electrode slurry is 5°C to 15°C, the cycle stability and storage performance of the battery can be further improved.

[0202] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A method for treating negative electrode slurry, characterized in that: include: The negative electrode slurry including the porous carbon is stored and / or transported at a temperature of 0° C. to 18° C.

2. The processing method according to claim 1, characterized in that: The negative electrode slurry is stored and / or transported at a temperature of 3°C to 10°C, and optionally stored and / or transported at a temperature of 3°C to 6°C.

3. The processing method according to claim 1 or 2, characterized in that: The negative electrode slurry is stored and / or transported at a stirring speed not exceeding 25 rpm.

4. The processing method according to any one of claims 1 to 3, characterized in that: The porous carbon includes hard carbon.

5. The processing method according to any one of claims 1 to 4, characterized in that: The solid content of the negative electrode slurry is 45% to 55%, and can be 48% to 53%; and / or After the negative electrode slurry is treated by the treatment method for 48 hours, the bubble volume per unit mass of the porous carbon does not exceed 4 mL / g.

6. The processing method according to any one of claims 1 to 5, characterized in that: The viscosity of the negative electrode slurry changes to 10000 mPa·s to 30000 mPa·s after being treated by the method for 48 hours.

7. The processing method according to any one of claims 1 to 6, characterized in that: The processing method specifically includes: preparing the negative electrode slurry, The negative electrode slurry is stored in a slurry storage tank and / or transported in a pipeline.

8. The processing method according to claim 7, characterized in that: The preparation of the negative electrode slurry satisfies at least one of the following conditions: (1) The maximum stirring speed is 800 rpm to 1800 rpm, and can be selected as 1000 rpm to 1500 rpm; (2) The temperature is 5°C to 35°C, and can be optionally 5°C to 15°C.

9. A device for treating negative electrode slurry, characterized in that: The device comprises: A cavity, used to contain the negative electrode slurry, wherein the negative electrode slurry includes porous carbon; A cooling device is used to cool the cavity so that the temperature of the cavity is 0-18°C.

10. The device according to claim 9, characterized in that The device includes at least one of a slurry storage tank and a transportation pipeline.

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