Negative electrode paste processing method and negative electrode paste processing device

Abstract

The invention provides a negative electrode slurry treatment method and device. The treatment method comprises the step of storing and / or transporting the negative electrode slurry at the temperature of 0-18 DEG C, wherein the negative electrode slurry comprises porous carbon. The treatment method can effectively improve the foaming and gelling phenomena of the negative electrode slurry, and improve the cycling stability and storage performance of the sodium secondary battery.

Description

Technical Field

[0001] 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

[0002] In recent years, secondary batteries have been widely used in energy storage power systems such as hydropower, thermal, wind and solar power stations, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields.

[0003] Compared with lithium secondary batteries, sodium secondary batteries have greater competitive advantages due to their abundant sodium resources and wide distribution. However, sodium secondary batteries have certain defects in preparation, storage and transportation processes. For example, the negative electrode slurry has foaming phenomenon, which makes it impossible to mass-produce sodium secondary batteries to meet market demand. Summary of the invention

[0004] 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.

[0005] 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.

[0006] 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 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.

[0007] 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. .

[0008] 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 to further increase 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 to water molecules, improve the foaming phenomenon of the negative electrode slurry, enhance the stability of the negative electrode slurry, and enhance the cycle performance and storage performance of the sodium secondary battery. In addition, it can also further reduce the increase in cost due to too low temperature.

[0009] In any embodiment, the negative electrode slurry is stored or transported at a stirring speed not exceeding 25 rpm.

[0010] The stirring speed of the negative electrode slurry during storage and / or transportation is controlled not to exceed 25rpm, 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 0rpm, which can significantly reduce the production cost. 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.

[0011] In any embodiment, the porous carbon comprises hard carbon.

[0012] In any embodiment, the solid content of the negative electrode slurry is 45% to 55%, and can be optionally 48% to 53%.

[0013] Controlling the solid content of the negative electrode slurry within a suitable 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.

[0014] In any embodiment, 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.

[0015] 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 the sodium secondary battery.

[0016] In any embodiment, the viscosity of the negative electrode slurry changes by 10000 mPa·s to 30000 mPa·s after being treated by the method for 48 hours.

[0017] The viscosity of the negative electrode slurry after being treated by the method for 48 hours changes to 10000 mPa·s to 30000 mPa·s, 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.

[0018] In any embodiment, 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.

[0019] 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.

[0020] In any embodiment, the temperature for preparing the negative electrode slurry is 5°C to 35°C, and can be 5°C to 15°C.

[0021] 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.

[0022] A second aspect of the present application provides a device for treating negative electrode slurry, the device comprising:

[0023] A cavity, used to contain the negative electrode slurry, wherein the negative electrode slurry includes porous carbon;

[0024] A cooling device is used to cool the cavity so that the temperature of the cavity is 0°C to 18°C.

[0025] The device equipped with a cooling device can control the temperature of the cavity, thereby improving the gelation and foaming phenomena of the negative electrode slurry, and enhancing the cycle stability and storage performance of its sodium secondary battery.

[0026] In any embodiment, the device includes at least one of a slurry storage tank and a transportation pipeline.

[0027] 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

[0028] Figure 1 a) is a schematic diagram of the structure of a slurry storage tank in one embodiment of the present application;

[0029] Figure 1 b) is a schematic diagram of the structure of a transport pipeline in one embodiment of the present application;

[0030] Figure 2 Schematic diagram of the division 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;

[0031] Figure 3 is a schematic diagram of a sodium secondary battery according to an embodiment of the present application;

[0032] Figure 4 yes Figure 3 An exploded view of a sodium secondary battery according to an embodiment of the present application is shown;

[0033] Figure 5 is a schematic diagram of a battery module according to an embodiment of the present application;

[0034] Figure 6 is a schematic diagram of a battery pack according to an embodiment of the present application;

[0035] Figure 7 yes Figure 6 An exploded view of a battery pack according to an embodiment of the present application is shown;

[0036] Figure 8 Schematic diagram of an electrical device using a sodium secondary battery according to an embodiment of the present application as a power source.

[0037] Description of reference numerals:

[0038] 61 slurry storage tank; 601 condensate water inlet of slurry storage tank; 602 condensate water outlet of slurry storage tank; 71 transport pipeline; 701 condensate water inlet of transport pipeline; 702 condensate water outlet of 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

[0039] Below, the embodiments of the negative electrode slurry processing method and device of the present application are specifically disclosed with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structure are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following descriptions are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0040] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a 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 a special range. The scope limited in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present 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 real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it 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.

[0041] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0042] 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.

[0043] If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means 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), which means 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.

[0044] If there is no special explanation, the "include" and "comprising" mentioned in this application are open-ended or closed-ended. For example, the "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0045] If not specifically stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0046] Compared with 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. The traditional graphite system has a solid-gas-liquid interface due to wetting, and the residual gas causes the negative electrode slurry to foam. The presence of surfactants in the negative electrode slurry causes air to enter the negative electrode slurry during stirring, further exacerbating the foaming phenomenon. The foaming phenomenon is usually improved by additives such as wetting agents or defoaming agents, which are surfactants with low surface tension. However, porous carbon has pores. During the preparation, storage and transportation of the negative electrode slurry, the solvent water molecules in the negative electrode slurry will slowly enter the pores of the porous carbon, discharge the gas adsorbed in the porous carbon pores, and cause the negative electrode slurry to foam. In particular, the foaming phenomenon is more serious during the storage and transportation of the negative electrode slurry. If a surfactant with low surface tension is introduced into the negative electrode slurry, it will further promote the solvent water molecules to enter the porous carbon pores, worsening the foaming. The foaming of negative electrode slurry is not conducive to the subsequent coating of negative electrode slurry. The foaming phenomenon of negative electrode slurry will also cause gelation problems, increase the difficulty of coating, and also have a great impact on the mass production and performance of sodium secondary batteries. Therefore, it is necessary to design a method for treating negative electrode slurry to improve the foaming and gelation phenomenon of negative electrode slurry, so that its products can meet the needs of the market.

[0047] [Method for treating negative electrode slurry]

[0048] 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.

[0049] Porous carbon materials refer to carbon materials with pore structures of different sizes, which have highly developed specific surface area and pore structure, and their pore sizes can range from ultrafine nano-scale micropores of molecular size to micro-scale pores suitable for microbial activities. According to the provisions of the International Union of Pure and Applied Chemistry (IUPAC), they can be divided into three types according to their pore sizes: micropores (<2nm), mesopores (2-50nm) and macropores (>50nm). In some embodiments, porous carbon includes hard carbon.

[0050] In some embodiments, the temperature for storage and / or transportation of the negative electrode slurry may be selected as 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.

[0051] Research has found that the sodium storage mechanism of porous carbon, especially hard carbon, can be simply summarized as: 1) adsorption of surfaces, defect sites and functional groups; 2) micropore filling; 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 negative electrode slurry using porous carbon as the negative electrode active material, the solvent water molecules will gradually enter the porous carbon pores, expel the gas adsorbed in the porous carbon pores, and cause a large number of bubbles in the negative electrode slurry, which deteriorates the stability of the negative electrode slurry. The foaming phenomenon of the negative electrode slurry will cause the negative electrode slurry to leak during the coating process, which will affect the distribution of the active material of the electrode sheet, resulting in fluctuations in the CB value and a serious risk of sodium precipitation.

[0052] 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 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.

[0053] Herein, "the temperature of storage and / or transportation of the negative electrode slurry is 0° C. to 18° C." can be detected by any temperature detection device, such as using a temperature sensor to measure the temperature.

[0054] In some embodiments, the negative electrode slurry is stored and / or transported at a temperature of 3°C to 10°C, and may be stored and / or transported at a temperature of 3°C to 6°C. In some embodiments, the temperature at which the negative electrode slurry is stored and / or transported may be 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.

[0055] 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 conducive to 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 to 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 also further reduce the increase in cost caused by too low temperature.

[0056] In some embodiments, the negative electrode slurry is stored and / or transported at a stirring speed of no more than 25 rpm.

[0057] 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.

[0058] 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 slow stirring state, both of which can achieve the effect of improving the gelation and foaming of the negative electrode slurry.

[0059] In some embodiments, the stirring speed of the negative electrode slurry during storage and / or transportation is 0 rpm-15 rpm.

[0060] A stirring speed of 0 rpm can significantly reduce production costs. Compared with the static state of the negative electrode slurry, slow stirring can prevent the slurry from settling while preventing the slurry from having low viscosity and excessive water from entering the porous carbon pores, which can 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.

[0061] In some embodiments, the porous carbon includes hard carbon.

[0062] In some embodiments, the solid content of the negative electrode slurry is 45% to 55%, and optionally 48% to 53%.

[0063] In some embodiments, the solid content of the negative electrode slurry may be selected to 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.

[0064] Controlling the solid content of the negative electrode slurry within a suitable 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.

[0065] In some embodiments, 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 / g.

[0066] In the present application, the test of the bubble volume per unit mass of porous carbon in the negative electrode slurry can be carried out by a method known in the art, such as sealing the negative electrode slurry (the mass of porous carbon in the negative electrode slurry is m, in g) into a sealed bag; and testing the gas change by the drainage method. The initial volume is V0, in mL, and the test volume after 48 hours is V1, in mL. Then the bubble volume per unit mass of porous carbon = (V1-V0) / m, in mL / g.

[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 porous carbon is 0 mL / g, 1 mL / g, 2 mL / g, 3 mL / g, 4 mL / g or a value in the range formed by any two of the above points.

[0068] 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.

[0069] In some embodiments, the viscosity of the negative electrode slurry after being treated by the method for 48 hours changes to 10000 mPa·s to 30000 mPa·s.

[0070] In the present 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 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°C, test time is 5 minutes, and read the data after the display is stable.

[0071] Re-test the viscosity of the negative electrode slurry after 48 hours of storage and / or transportation, and use a rotating viscometer to measure the viscosity of the negative electrode slurry. Select a suitable rotor, fix the viscometer rotor, and place the negative electrode slurry under the viscometer rotor. 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°C, test time is 5 minutes, and read the data after the display is stable. 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.

[0072] In some embodiments, the viscosity of the negative electrode slurry after being placed at 25° C. for 48 hours changes to 10000 mPa·s, 15000 mPa·s, 20000 mPa·s, 25000 mPa·s, 30000 mPa·s, or a value in a range consisting of any two of the above points.

[0073] The viscosity of the negative electrode slurry after being treated by the method for 48 hours changes to 10000 mPa·s to 30000 mPa·s, 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.

[0074] 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.

[0075] In some embodiments, 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.

[0076] 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 points.

[0077] 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.

[0078] In some embodiments, the temperature for preparing the negative electrode slurry is 5° C. to 35° C., and can be 5° C. to 15° C. In some embodiments, the temperature for preparing the negative electrode slurry can be 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 above points.

[0079] 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.

[0080] In some embodiments, preparing the negative electrode slurry further comprises:

[0081] 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; optionally, the raw materials also include a plasticizer.

[0082] In some embodiments, the negative electrode active material includes hard carbon.

[0083] In some embodiments, the conductive agent includes one or more of SuperP, Ketjen black, acetylene black, carbon nanotubes, and graphene, and may optionally include SuperP.

[0084] In some embodiments, the binder includes one or more of styrene-butadiene rubber, polyacrylic acid, polyacrylate, polyamide, poly(acrylonitrile-acrylate), poly(styrene-acrylate), and optionally includes styrene-butadiene rubber.

[0085] In some embodiments, the dispersing agent comprises sodium carboxymethylcellulose.

[0086] In some embodiments, the plasticizer includes 1,3,-butanediol.

[0087] 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.

[0088] [Device for processing negative electrode slurry]

[0089] In some embodiments, the present application also provides a device for treating negative electrode slurry, the device comprising:

[0090] A cavity, for containing negative electrode slurry, wherein the negative electrode slurry comprises porous carbon;

[0091] The cooling device is used to cool the cavity so that the temperature in the container is 0°C to 18°C.

[0092] The device equipped with a cooling device can control the temperature of the cavity, thereby improving the gelation and foaming phenomena of the negative electrode slurry, and enhancing the cycle stability and storage performance of its sodium secondary battery.

[0093] 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.

[0094] In some embodiments, the temperature detection device is a temperature sensor.

[0095] The temperature detection device can control the temperature of the cavity to 0°C ~ 18°C, thereby improving the gel and foaming phenomena of the negative electrode slurry, and enhancing the cycle stability and storage performance of its sodium secondary battery.

[0096] In some embodiments, the device includes at least one of a slurry storage tank and a transportation pipeline.

[0097] like Figure 1 a) and Figure 1 As shown in b), 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. Alternatively, 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.

[0098] The negative electrode slurry can be placed in a slurry storage tank for storage, or placed in a transportation pipeline for transportation.

[0099] 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.

[0100] 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.

[0101] [Negative electrode]

[0102] 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.

[0103] 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 any one or both of the two opposite surfaces of the negative electrode current collector.

[0104] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, a copper 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 substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0105] In some embodiments, the negative electrode film layer is prepared from negative electrode slurry processed by the negative electrode slurry processing method in some embodiments.

[0106] In some embodiments, the negative electrode film layer may further include a binder. As an 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).

[0107] In some embodiments, the negative electrode film layer may further include a conductive agent. As an 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.

[0108] In some embodiments, the negative electrode film layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0109] 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.

[0110] [Positive electrode]

[0111] 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.

[0112] 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 any one or both of the two opposite surfaces of the positive electrode current collector.

[0113] In some embodiments, the positive electrode current collector can be a metal foil or a composite current collector. For example, as the metal foil, aluminum foil can be used. The composite current collector can 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 can 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.).

[0114] In some embodiments, the positive electrode active material can be a positive electrode active material for batteries well-known in the art. As an example, the positive electrode active material can 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 can also be used. These positive electrode active materials can 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.

[0115] In some embodiments, the positive electrode film layer may also optionally include a binder. As an example, the binder can 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.

[0116] In some embodiments, the positive electrode film layer may also optionally include a conductive agent. As an example, the conductive agent can include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0117] In some embodiments, the positive electrode sheet can be prepared in the following manner: 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 collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0118] [Electrolytes]

[0119] The electrolyte plays the role of conducting ions between the positive electrode and the negative electrode. The present application has no specific restrictions on the type of electrolyte, which can be selected according to needs. For example, the electrolyte can be liquid, gel or all-solid.

[0120] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.

[0121] 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.

[0122] 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.

[0123] In some embodiments, the electrolyte includes a solvent, and the solvent includes at least one of a chain carbonate, a chain carboxylic acid ester, 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 carboxylic acid ester 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.

[0124] In some embodiments, the electrolyte may further include additives, such as 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, additives that improve battery high or low temperature performance, etc.

[0125] [Isolation film]

[0126] In some embodiments, the sodium secondary battery further includes a separator, which can be any known porous structure separator with good chemical stability and mechanical stability.

[0127] In some embodiments, the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The isolation membrane can be a single-layer film or a multi-layer composite film. When the isolation membrane is a multi-layer composite film, the materials of each layer can be the same or different.

[0128] In some embodiments, the isolation film further has at least one of a bonding coating and a ceramic coating.

[0129] [Sodium secondary battery]

[0130] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly by a winding process or a lamination process.

[0131] In some embodiments, the sodium secondary battery may include an outer package that can be used to encapsulate the electrode assembly and the electrolyte.

[0132] 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, a steel shell, etc. The outer packaging of the sodium secondary battery can also be a soft package, such as a bag-type soft package. The material of the soft package can be plastic, and as the plastic, polypropylene, polybutylene terephthalate, and polybutylene succinate can be listed.

[0133] The shape of the sodium secondary battery in this application can be cylindrical, square or any other shape. For example, Figure 3 A sodium secondary battery 5 having a square structure is used as an example.

[0134] In some embodiments, reference Figure 4 , the outer packaging may include a shell 51 and a cover plate 53. Among them, 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 are enclosed to form a accommodating cavity. The shell 51 has an opening connected to the accommodating cavity, and the cover plate 53 can be covered on the opening to close the accommodating cavity. The positive electrode sheet, the negative electrode sheet and the isolation membrane can form an electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is encapsulated in the accommodating 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.

[0135] In some embodiments, the 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, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

[0136] Figure 5 4 is an example of a battery module. Figure 5 In the battery module 4, the plurality of sodium secondary batteries 5 may be arranged in sequence along the length direction of the battery module 4. Of course, they may also be arranged in any other manner. Further, the plurality of sodium secondary batteries 5 may be fixed by fasteners.

[0137] Optionally, the battery module 4 may further include a housing having a housing space, and the plurality of sodium secondary batteries 5 are housed in the housing space.

[0138] 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 according to the application and capacity of the battery pack.

[0139] Figure 6 and Figure 7 1 is a battery pack 1 as an example. Figure 6 and Figure 7 The battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box. The battery box includes an upper box body 2 and a lower box body 3. The upper box body 2 can cover the lower box body 3 and form a closed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0140] 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 are not limited thereto.

[0141] As the electrical device, a sodium secondary battery, a battery module or a battery pack may be selected according to its usage requirements.

[0142] Figure 8 The power consumption device is taken as an example. The power consumption device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. In order to meet the power consumption device's requirements for high power and high energy density of sodium secondary batteries, a battery pack or a battery module can be used.

[0143] Another example of a device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is usually required to be thin and light, and a sodium secondary battery may be used as a power source.

[0144] Example

[0145] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If no specific techniques or conditions are indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0146] 1. Preparation method

[0147] Example 1

[0148] 1) Treatment of negative electrode slurry

[0149] 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.

[0150] 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 mixed mixture;

[0151] The dry mixed mixture was mixed with solvent water and kneaded for 60 minutes to obtain an adhesive mixture with a solid content of 65%;

[0152] The adhesive mixture and sodium carboxymethyl cellulose with a weight average molecular weight of 400,000 are mixed, and solvent water is added and stirred evenly at a stirring speed of 1600 rpm for 45 minutes to obtain a first adhesive solution;

[0153] 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 the stirring was continued at a speed of 700 rpm and a stirring time of 25 min to obtain a negative electrode slurry with a solid content of 50%;

[0154] The temperature of the above preparation process was controlled at 15°C.

[0155] Treatment of negative electrode slurry: The negative electrode slurry is first placed in a slurry storage tank at a temperature of 5°C, and then transported to a transportation pipeline at a temperature of 5°C by a pump. The storage time in the slurry storage tank is 24 hours, the transportation time in the transportation pipeline is 24 hours, and the linear speed of the transportation pipeline is 20m / s. The bubble volume per unit mass of hard carbon in the treated negative electrode slurry is 0mL, and the viscosity change is 14223mPa·s.

[0156] 2) Negative electrode

[0157] The negative electrode slurry treated as above was evenly coated on a 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 h, and then cold pressed and cut to obtain a negative electrode sheet.

[0158] 3) Positive electrode

[0159] The cathode 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 cathode slurry; the cathode slurry was mixed at 0.28 g (dry weight) / 1540.25 mm 2 The 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 sheet is obtained through cold pressing and slitting.

[0160] 4) Electrolyte

[0161] 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.

[0162] 5) Isolation film

[0163] A 12 μm polyethylene (PE) porous polymer film was used as the isolation membrane.

[0164] 6) Preparation of batteries

[0165] The positive electrode sheet, the separator, and the negative electrode sheet are stacked in order, so that the separator is located between the positive and negative electrode sheets to isolate the positive and negative electrode sheets, and the bare battery cell is wound, and the pole ears are welded. The bare battery cell is placed in an outer package, and the prepared electrolyte is injected into the dried battery cell. After packaging, standing, formation, shaping, capacity testing and other processes, the sodium secondary battery product of Example 1 is obtained.

[0166] The preparation methods of the sodium secondary batteries of Examples 2-7 are substantially the same as the preparation method of Example 1, except that the temperature of the slurry storage tank or the transport pipeline is adjusted. The specific parameters are shown in Table 1.

[0167] 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. The specific parameters are shown in Table 1.

[0168] The preparation methods of the sodium secondary batteries of Examples 11 and 12 are substantially the same as the preparation method of Example 1, except that the maximum stirring speed of the first glue solution in the preparation process of the negative electrode slurry is adjusted. The specific parameters are shown in Table 1.

[0169] The preparation methods of the sodium secondary batteries of Examples 13 and 14 are substantially the same as the preparation method of Example 1, except that the temperature during the preparation of the negative electrode slurry is adjusted. The specific parameters are shown in Table 1.

[0170] The preparation method of the sodium secondary battery in Example 15 is basically the same as the preparation method in Example 1, except that the negative electrode slurry is only stored in the slurry storage tank, and the storage time is 48 hours. The specific parameters are shown in Table 1.

[0171] 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.

[0172] 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.

[0173] 2. Performance Test

[0174] 1. Negative electrode slurry

[0175] 1) Viscosity change test of negative electrode slurry after 24 hours and 48 hours of storage and / or transportation

[0176] Use a rotating 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), rotation speed: 12 rpm, test temperature: 25℃, test time is 5 minutes, and read the data after the display is stable.

[0177] Re-test the viscosity of the negative electrode slurry after 24 hours of storage and / or transportation, and use a rotating viscometer to measure the viscosity of the negative electrode slurry. Select a suitable rotor, fix the viscometer rotor, and place the negative electrode slurry under the viscometer rotor. 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°C, test time is 5 minutes, and read the data after the display is stable. 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.

[0178] Re-test the viscosity of the negative electrode slurry after 48 hours of storage and / or transportation, and use a rotating viscometer to measure the viscosity of the negative electrode slurry. Select a suitable rotor, fix the viscometer rotor, and place the negative electrode slurry under the viscometer rotor. 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°C, test time is 5 minutes, and read the data after the display is stable. 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.

[0179] 2) Gel state test of negative electrode slurry after 48 hours of storage and / or transportation

[0180] After the negative electrode slurry is stored and / or transported for 48 hours, take an appropriate amount of the negative electrode slurry into a beaker, use a steel ruler to pick up the negative electrode slurry in the beaker, and judge the gel state of the negative electrode slurry according to the flow state of the negative electrode slurry;

[0181] The gel-free state is that the negative electrode slurry flows naturally and continuously, and the negative electrode slurry flows on the surface of the steel ruler without agglomeration. Figure 2 a) as shown;

[0182] The slight gel state is that the negative electrode slurry flows naturally and continuously, but the fluid is thin, and the negative electrode slurry is basically spread flat on the surface of the steel ruler, with slight small pieces, such as Figure 2 b) as shown;

[0183] 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, and there are obvious block agglomerations, such as Figure 2 c) as shown;

[0184] Severe gel state means that the negative electrode slurry cannot flow down in a stream, but falls off in lumps or remains directly on the steel ruler and cannot flow down. Figure 2 d).

[0185] 3) Bubble volume test in negative electrode slurry

[0186] After 48 hours of storage and / or transportation, the negative electrode slurry (the mass of hard carbon in the negative electrode slurry is m, in g) is sealed in a sealed bag; the gas change is tested by the water displacement method. The initial volume is V0, in mL, and the test volume after 48 hours is V1, in mL. Then the gas generation rate of the negative electrode slurry = (V1-V0) / m, in mL / g.

[0187] 2. Battery

[0188] 1) Cycle performance

[0189] 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 cycles were 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 for evaluating the battery cycle performance.

[0190] 2) Storage 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, and after standing for 10 minutes, discharged to 1.5V at a constant current of 1C. This is a charge / discharge cycle of the battery, with the capacity of the first discharge being 100%. The battery was then placed in a 60°C oven, and after being stored for a period of time, the battery was taken out and the above charging steps were repeated again, and 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 when the capacity retention rate reached 80% were used as an indicator to evaluate the battery storage performance.

[0192] III. Analysis of test results of various embodiments and comparative examples

[0193] The batteries of the embodiments and comparative examples were prepared according to the above method, and various performance parameters were measured. The results are shown in Table 1 below.

[0194] Table 1

[0195]

[0196] In Examples 1 to 16, the negative electrode slurry is stored and / or transported at a temperature of 0°C to 18°C, and the negative electrode slurry includes hard carbon. As can be seen from Examples 1 to 16, when the negative electrode slurry including hard carbon is stored and / or transported at a temperature of 0°C to 18°C, the gelation of the negative electrode slurry is improved, the bubbling volume per unit mass of hard carbon is small, and the battery has good cycle stability and storage performance.

[0197] From the comparison between 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 gel state of the slurry, reduce the bubble volume per unit mass of hard carbon, and enhance the cycle stability and storage performance of the battery.

[0198] It can be seen from Examples 1 and 8-10 that when the stirring speed of the slurry storage tank does not exceed 25 rpm, after the prepared slurry is stored and / or transported at a temperature of 0°C to 18°C, the negative electrode slurry does not gel, 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.

[0199] 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.

[0200] It can be seen from Examples 1, 14, and 15 that when the temperature for preparing the negative electrode slurry is 5°C to 35°C, after the prepared slurry is stored and / or transported at a temperature of 0°C to 18°C, the negative electrode slurry does not gel, 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.

[0201] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining 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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