Battery manufacturing process, battery treatment device, battery, and power-consuming device

Abstract

The present application relates to the technical field of batteries, and particularly to a battery manufacturing process, a battery treatment device, a battery, and a power-consuming device. The battery manufacturing process comprises: obtaining a battery to be subjected to treatment, and subjecting the battery to electrolyte injection; and charging the battery before sodium in the battery is reduced at the negative electrode. In the present application, the battery is charged before sodium in the battery is reduced at the negative electrode; during the process of charging the battery, water can receive electrons at the negative electrode to undergo a reduction reaction so as to produce hydrogen and hydroxy radicals, or water is decomposed in the electrolyte to produce hydrogen ions, and the hydrogen ions can receive the electrons at the negative electrode to undergo a reduction reaction so as to produce hydrogen; in such a way, water in the battery can be removed; after the water removal, sodium is reduced at the negative electrode to produce an elementary sodium metal, thus reducing the risk of the reduced sodium reacting with water, reducing a loss of battery capacity, and improving the cycling performance of the battery.

Description

Battery manufacturing process, battery processing equipment, batteries and electrical equipment

[0001] Related applications

[0002] This application claims priority to Chinese patent application No. 202310973398.6 filed on August 3, 2023, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the field of battery technology, and in particular to a battery manufacturing process, a battery processing device, a battery, and an electrical device. Background Art

[0004] Secondary batteries have the advantages of high energy density, high output voltage, good safety, no pollution, and no memory effect. They have been widely used in various consumer electronic products and electric vehicles.

[0005] The presence of water inside the battery will affect the performance of the battery. The sources of water inside the battery include water in the electrode, water in the electrolyte, etc. In order to improve the performance of the battery, the water content in the battery needs to be strictly controlled during the battery preparation process.

[0006] Summary of the Invention

[0007] The main purpose of this application is to provide a battery manufacturing process to improve the cycle performance of the battery.

[0008] To achieve the above objectives, the present application proposes a battery manufacturing process, comprising:

[0009] Obtaining a battery to be processed;

[0010] injecting liquid into the battery;

[0011] The battery is charged before the sodium in the battery is reduced at the negative electrode.

[0012] In the prior art, water is generally removed from the battery by high-temperature baking. However, this water removal method is difficult to effectively remove water from the battery.

[0013] The present application adopts a charging method to remove water. Specifically, a battery to be processed is obtained; the battery is injected with liquid. Considering the presence of water in the electrode and the diaphragm, the battery is injected with liquid so that the electrolyte infiltrates the electrode and the diaphragm, and the moisture in the electrode and the diaphragm is infiltrated into the electrolyte to facilitate the subsequent removal of water.

[0014] For sodium batteries, sodium ions are first reduced on the current collector before the additive begins to form a film on the negative electrode. It is understood that the reduction of sodium to sodium metal at the negative electrode can include sodium reduction to sodium metal on the negative electrode surface or embedding sodium metal into the negative electrode (for example, when the negative electrode includes a negative electrode active material, sodium metal is embedded within the layered negative electrode active material). The reduced sodium metal is highly reactive and easily reacts violently with water in the battery to generate gases such as H2, resulting in a large amount of capacity loss.

[0015] In order to solve the above problems, the present application adopts the method of charging the battery before the sodium in the battery is reduced at the negative electrode. During the charging process of the battery, water can receive electrons at the negative electrode to undergo a reduction reaction, producing hydrogen and hydroxide, or water can decompose in the electrolyte to generate hydrogen ions, which receive electrons at the negative electrode to undergo a reduction reaction, producing hydrogen. In this way, the water in the battery is removed. After the water is removed, the sodium is reduced at the negative electrode to generate sodium metal element, reducing the risk of the reduced sodium reacting with the water, alleviating the problem of battery capacity loss, and improving the battery's cycle performance. That is, before sodium reduction occurs at the negative electrode, the water in the battery cell is removed as much as possible, thereby reducing the adverse effects of water on the subsequent operation of the battery cell.

[0016] Optionally, the step of charging the battery includes:

[0017] The battery is charged at a first charging voltage, wherein the first charging voltage is higher than H + The first charging voltage is lower than the reduction potential of sodium.

[0018] The battery is charged at a first charging voltage, and the first charging voltage is higher than H + The reduction potential of the first charge voltage is lower than the reduction potential of sodium. In this way, water can undergo a reduction reaction at the negative electrode at this charge voltage, and water gains electrons at the negative electrode to generate H2, for example, 2H2O+4e - →H2+2OH - Alternatively, water can react with NaPF6 in the electrolyte to produce hydrogen ions, which receive electrons at the negative electrode and are reduced to H2, such as 2H2O+NaPF6+4e - →NaPO2F2+2H2+4F - It is understandable that, at the same time, it is difficult for sodium reduction and precipitation to occur at this voltage, that is, it is difficult for sodium to be reduced at the negative electrode.

[0019] Optionally, the battery is a sodium battery without a negative electrode system, and the first charging voltage is lower than the deposition potential of sodium;

[0020] Alternatively, the battery is a sodium battery with a negative electrode system, the first charging voltage is lower than the reduction potential of the electrolyte additive, and the reduction potential of the electrolyte additive is in the range of 1.5V to 2.5V.

[0021] It can be understood that a battery without a negative electrode system means that the negative electrode current collector does not include the negative electrode active material. For example, taking a sodium battery as an example, a battery without a negative electrode system means that the ions in the negative electrode are no longer embedded in the layered material and exist in the form of ions, but form sodium elements directly on the negative electrode current collector.

[0022] A battery with a negative electrode system means that the negative electrode current collector is provided with a negative electrode active material, such as hard carbon and other materials. For example, taking a sodium battery as an example, a battery with a negative electrode system means that ions are embedded in the layered material in the negative electrode and exist in the form of ions.

[0023] It is understandable that the sodium in the negative electrode-free sodium battery is deposited in the negative electrode in the form of a single substance. When the water in the battery is not removed during the sodium deposition process, it not only affects the capacity loss of sodium, but also affects the further deposition of sodium at the negative electrode. It is understandable that if there is still water in the battery before the sodium deposition, the deposited sodium will react violently with the water. The sodium deposited on the negative electrode is unevenly distributed on the surface of the negative electrode. In the subsequent process of further sodium deposition, it cannot be evenly deposited on the negative electrode, thus affecting the further deposition effect of sodium. It is also understandable that the uneven deposition of sodium can easily cause local dendrites, which makes the battery cell prone to short circuit.

[0024] Considering that during the charging process of the battery at the first charging voltage, water can receive electrons at the negative electrode to undergo a reduction reaction to produce hydrogen and hydroxide, or water can decompose in the electrolyte to generate hydrogen ions, and the hydrogen ions receive electrons at the negative electrode to undergo a reduction reaction to produce hydrogen, it is assumed that when the battery is charged at the first charging voltage, the electrolyte additive reacts to participate in the formation of a film at the negative electrode interface. At this time, the film formed at the negative electrode interface will hinder the water or H + Migrate to the negative electrode (for example, when the water migrates from the positive electrode to the negative electrode, the film formed on the negative electrode interface will prevent the water from reaching the negative electrode surface, that is, the film formed on the negative electrode interface makes it difficult for water to receive electrons at the negative electrode). At this time, water or H +Because the film formed at the negative electrode interface is difficult to accept electrons at the negative electrode, the water removal effect is reduced. Therefore, during the charging process at the first charging voltage, the phenomenon of film formation at the negative electrode should be reduced. That is, the first charging voltage is lower than the reduction potential of the electrolyte additive. Specifically, when the battery is a sodium battery with a negative electrode system, the first charging voltage is lower than the reduction potential of the electrolyte additive, and the reduction potential range of the electrolyte additive is 1.5V to 2.5V. For example, in one embodiment, when the reduction potential of the electrolyte additive is 2V, the first charging voltage is lower than 2V. When the first charging voltage is lower than the reduction potential of the electrolyte additive, the phenomenon of the electrolyte additive participating in film formation at the negative electrode can be reduced, and the water removal effect can be improved.

[0025] Optionally, the first charging voltage ranges from 1.0V to 2.9V, preferably from 1.7V to 2.9V, and preferably from 2.5V to 2.7V.

[0026] It can be understood that when the first charging voltage is low, the reduction reaction of water is weak and it is difficult to effectively remove water. When the first charging voltage is high, sodium reduction and precipitation will occur. In order to avoid the above problems, the range of the first charging voltage is 1.0V to 2.9V, preferably 1.7V to 2.9V, and more preferably 2.5V to 2.7V.

[0027] It can be understood that, considering that when the battery is a sodium battery without a negative electrode system, the first charging voltage is lower than the reduction potential of the electrolyte additive, and the reduction potential range of the electrolyte additive is greater than 2.9V and less than or equal to 3.5V, for the sodium battery without a negative electrode system, at this time, in one embodiment, the range of the first charging voltage can be 1.0V to 2.9V, that is, in actual operation, the appropriate first charging voltage is selected according to the specific battery type and the reduction potential of the additive in the electrolyte.

[0028] When the battery is a sodium battery with a negative electrode system, the first charging voltage is lower than the reduction potential of the electrolyte additive, and the reduction potential range of the electrolyte additive is 1.5V to 2.5V. At this time, in one embodiment, the first charging voltage can be in the range of 1.0V to 1.49V. That is, in actual operation, the appropriate first charging voltage is selected according to the specific battery type and the reduction potential of the additive in the electrolyte.

[0029] Optionally, the step of charging the battery at the first charging voltage further includes heating the battery.

[0030] It can be understood that during the charging process of the battery at the first charging voltage, water can receive electrons at the negative electrode to undergo a reduction reaction to produce hydrogen and hydroxide, or water can decompose in the electrolyte to generate hydrogen ions, which receive electrons at the negative electrode to undergo a reduction reaction to produce hydrogen. When the water or H+ When the water is continuously diffused to the negative electrode, the water removal efficiency is improved. In order to effectively diffuse the water in the battery to the negative electrode, for example, to release the water in the electrode, the battery is heated. The battery has an appropriate temperature so that the water in the battery material can be quickly dissolved into the electrolyte phase, that is, the electrolyte fully infiltrates the battery material, so that the water is continuously diffused to the negative electrode side (or the H generated by the hydrolysis of the sodium salt). + Driven by the electric field, it migrates to the negative electrode side. Under the effective voltage, water or H + Continuous reduction on the negative electrode side produces hydrogen, thus improving the water removal effect.

[0031] It is also understandable that, in theory, the battery can be heated before charging the battery at the first charging voltage, so that the moisture in the battery core material is released into the electrolyte in advance.

[0032] Optionally, in the step of heating the battery, the temperature of the battery ranges from 25°C to 70°C, preferably from 45°C to 60°C.

[0033] The battery is heated. The water removal effect is best when the battery temperature is between 25°C and 70°C, preferably between 45°C and 60°C. It is understood that the battery temperature should not be too high. Excessive temperature will cause the low-boiling-point additives in the battery to evaporate, causing the battery to swell. Furthermore, when removing hydrogen generated inside the battery during charging, the low-boiling-point additives will be discharged from the battery, resulting in the loss of the low-boiling-point additives and affecting battery performance.

[0034] Optionally, during the process of charging the battery at the first charging voltage, the battery is further vacuumed.

[0035] Theoretically, water is reduced to produce H2 during the water removal process. At this time, a pressure difference will be formed inside and outside the battery. When the battery is opened, H2 will be released from the inside of the battery. However, in order to speed up the water removal, the chemical equilibrium reaction is made to proceed towards the reaction product, for example, 2H2O+NaPF6+4e - →NaPO2F2+2H2+4F - The battery maintains a certain vacuum level during the dehydration process, allowing the H2 generated within the cell to be promptly removed. This allows the electrochemical balance to continuously shift towards H2 production, improving the dehydration effect.

[0036] Optionally, in the step of evacuating the battery, the vacuum degree inside the battery is in a range of greater than or equal to -80 kPa and less than 0 kPa, preferably -30 kPa to -10 kPa.

[0037] Maintaining a vacuum within the aforementioned range effectively removes H2 from the battery. However, the vacuum should not be too high, as this can cause electrolyte loss and loss of low-boiling-point additives. For these reasons, the battery's internal vacuum is maintained within the aforementioned range.

[0038] Optionally, in the step of charging the battery at the first charging voltage, the charging time is 4 hours to 48 hours, preferably 6 hours to 18 hours.

[0039] It is understandable that as the charging time of the battery at the first charging voltage increases, the water inside the battery is continuously removed. However, when the charging time is further extended, the water removal effect is not obvious. In order to ensure that the water or H + While being removed, the production efficiency and energy consumption are increased to the optimal level. The charging time is 4h to 48h, preferably 6h to 18h. It can be understood that the water removal efficiency is close to 90% in 12h.

[0040] Optionally, in the step of charging the battery at the first charging voltage, the charging method includes one of constant voltage charging, step voltage charging, and cyclic charging.

[0041] Constant voltage charging means charging at a constant voltage during the charging time. For example, if the charging time is 6 hours, the battery is charged at a constant voltage of 2V during the 6 hours.

[0042] Step voltage charging means changing the voltage during the charging time. For example, if the charging time is 6 hours, the battery is first charged at 2V for 2 hours, then at 2.5V for 2 hours, and then at 2.7V for 2 hours.

[0043] Cyclic charging refers to repeating a charge and discharge cycle multiple times within the charging time. For example, a charge and discharge cycle includes charging at a rate of 0.23C to a voltage of 2.5V, then discharging at a rate of 0.23C to a voltage of 2.0V, and repeating the above charge and discharge process.

[0044] It is understood that the present application prefers a constant voltage charging method, which can of course be cyclic charging within a certain voltage range, or charging in a step voltage rising manner. That is, constant voltage charging is a charging method that maintains a constant voltage at a suitable voltage. For example, in one embodiment, before sodium reduction, the electric field strength in the battery is kept at a maximum (voltage is maximum), and the direction of the electric field is always consistent, thereby ensuring that water or hydrogen ions move directionally from the positive electrode to the negative electrode at the maximum rate. The constant voltage charging method can make the interior of the battery always at the maximum electric field strength, which helps to improve the effect of water removal.

[0045] Optionally, after charging the battery at the first charging voltage, the method further includes the following steps:

[0046] The battery is charged at a second charging voltage that is higher than the reduction potential of sodium and / or higher than the reduction potential of the electrolyte additive.

[0047] It is understood that water removal is performed before sodium reduction, and after water removal, the battery is charged for a second time, and the battery is charged at a second charging voltage, which is higher than the reduction potential of sodium and / or higher than the reduction potential of the electrolyte additive. In this way, sodium is reduced or sodium ions are intercalated into the negative electrode active material, or the additive in the electrolyte forms a film at the negative electrode. It is understood that for a sodium secondary battery with a negative electrode system (the negative electrode includes a negative electrode active material), during the second charging process, the second charging voltage is higher than the reduction potential of the electrolyte additive, which can enable the electrolyte additive to participate in film formation and form protection for the interface; for a sodium secondary battery without a negative electrode system, the second charging voltage is higher than the reduction potential of sodium, so that sodium is effectively deposited at the negative electrode.

[0048] Optionally, the second charging voltage has a range of greater than 2.9V and less than or equal to 4.2V.

[0049] The range value of the second charging voltage satisfies the above range. For sodium secondary batteries without a negative electrode system, sodium deposition can be effectively achieved. For sodium secondary batteries with a negative electrode system, sodium ions can be effectively embedded in the negative electrode active material.

[0050] Optionally, after the battery is charged at the second charging voltage, the method further includes the steps of injecting liquid into the battery, evacuating the battery, injecting a protective gas, and sealing the battery.

[0051] It can be understood that the charging process of the second charging voltage can be regarded as a formation step. The battery needs to be formed during the preparation process of the battery. There will be electrolyte loss in the formation process (for example, part of the electrolyte is drawn away by negative pressure, and part of the electrolyte is reacted). Therefore, after formation, liquid injection, vacuuming, protective gas injection, and sealing steps are required.

[0052] Optionally, the positive electrode active material of the battery includes at least one of Na3MnTi(PO4)3, Na3MnV(PO4)3, Na3TiV(PO4)3, Na3Fe2(PO4)3, and Na3MnZr(PO4)3.

[0053] The positive electrode active material of the battery of the present application includes but is not limited to at least one of Na3MnTi(PO4)3, Na3MnV(PO4)3, Na3TiV(PO4)3, Na3Fe2(PO4)3, and Na3MnZr(PO4)3.

[0054] It is understandable that for battery cells that are difficult to remove moisture from through the "high-temperature baking" process, such as Nasicon-type phosphate positive electrode material system battery cells, moisture can be removed through electrochemical dehydration technology, thereby improving the cycle life of the battery cells and reducing the risk of gas production.

[0055] The present application also provides a battery processing device, comprising:

[0056] a battery acquisition unit configured to obtain a battery to be processed, wherein the battery is filled with an electrolyte;

[0057] The charging unit is configured to control the battery to be charged before the sodium in the battery is reduced at the negative electrode.

[0058] A battery processing device can be used to remove water from the battery. The battery processing device includes a battery acquisition unit and a charging unit. The battery acquisition unit is configured to obtain the battery to be processed, and the battery is filled with electrolyte; the charging unit is configured to control the sodium in the battery to charge the battery before the negative electrode is reduced.

[0059] Optionally, the charging unit includes a first charging unit, wherein the first charging unit is configured to control the battery to be charged at a first charging voltage, wherein the first charging voltage is higher than H + The first charging voltage is lower than the deposition potential of sodium.

[0060] The charging unit includes a first charging unit configured to control the battery to be charged at a first charging voltage, the first charging voltage being higher than H + The first charging voltage is lower than the deposition potential of sodium.

[0061] The battery is charged at a first charging voltage controlled by the first charging unit, and the first charging voltage is higher than H + The first charging voltage is lower than the sodium deposition potential. Thus, water reduction occurs at this charging voltage. At the same time, sodium reduction precipitation is unlikely to occur at this voltage.

[0062] Optionally, the charging unit further includes a heating unit, wherein the heating unit is configured to heat the battery in response to the first charging unit controlling the battery to charge at the first charging voltage;

[0063] And / or, the charging unit further includes a vacuum unit, and the vacuum unit is configured to vacuum the battery in response to the first charging unit controlling the battery to charge at the first charging voltage.

[0064] The battery is heated by the heating unit, and the battery has an appropriate temperature, so that the water in the battery material can be quickly dissolved into the electrolyte phase, that is, the electrolyte fully infiltrates the battery material, so that the water continues to diffuse to the negative electrode side (or the H generated by the hydrolysis of sodium salt). + Driven by the electric field, it migrates to the negative electrode side. Under the effective voltage, water or H + Continuous reduction on the negative electrode side produces hydrogen, thus improving the water removal effect.

[0065] The vacuum unit is used to control the vacuum degree inside the battery during the dehydration process, so that the H2 generated in the battery cell can be removed in time, and the electrochemical balance continues to move towards the production of H2, thereby improving the dehydration effect.

[0066] The present application also provides a battery, including a battery prepared by the battery manufacturing process as described above.

[0067] The present application also provides an electrical device, which includes the battery as described above.

[0068] This application uses the method of charging and removing water from the battery before the sodium in the battery is reduced at the negative electrode. In this way, after the water is removed, the sodium is reduced at the negative electrode, reducing the risk of the reduced sodium reacting with water, alleviating the problem of battery capacity loss, and improving the battery's cycle performance. In other words, before sodium reduction occurs at the negative electrode, the water in the battery cell is removed as much as possible, thereby reducing the adverse effects of water on the subsequent operation of the battery cell.

[0069] Moreover, through the battery manufacturing process of the present application, the proton hydrogen at the end of the alcohol substance can be reduced to generate H2, thereby improving the battery interface. That is, the battery manufacturing process of the present application can remove the proton hydrogen at the end of the compound containing terminal hydroxyl groups. Specifically, some alcohol substances, such as ethylene glycol, 1,3-butanediol, etc., are added to the pole piece as plasticizers to improve the toughness of the pole piece. However, as these plasticizers accumulate, the problem of increased interface impedance will be caused, thereby worsening the battery performance. The battery manufacturing process of the present application can alleviate the above problems, that is, before the sodium in the battery is reduced at the negative electrode, the battery is charged. During the charging process, the proton hydrogen at the end of the alcohol substance can be reduced to generate H2, thereby alleviating the problem of increased interface impedance caused by these alcohol substances.

[0070] That is, the battery manufacturing process of the present application can improve the cycle life of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0072] FIG1 is a schematic diagram of the process flow of the battery manufacturing process of the present application;

[0073] FIG2 is a schematic diagram of a battery module provided in an embodiment of the present application;

[0074] FIG3 is a schematic diagram of a battery pack provided in an embodiment of the present application;

[0075] FIG4 is an exploded view of the battery pack provided by the embodiment of the present application shown in FIG3 ;

[0076] FIG5 is a schematic diagram of an electrical device using a secondary battery provided in an embodiment of the present application as a power source.

[0077] Description of Figure Numbers:

[0078] The realization of the objectives, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0079] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0080] Below, with appropriate reference to the accompanying drawings, the embodiments of the battery manufacturing process, battery processing device, battery, and electrical equipment disclosed in this 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.

[0081] " 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.

[0082] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0083] 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.

[0084] 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.

[0085] Secondary batteries have the advantages of high energy density, high output voltage, good safety, no pollution, and no memory effect. They have been widely used in various consumer electronic products and electric vehicles.

[0086] The presence of water inside the battery will affect the performance of the battery. The sources of water inside the battery include water in the electrode, water in the electrolyte, etc. In order to improve the performance of the battery, the water content in the battery needs to be strictly controlled during the battery preparation process.

[0087] In order to solve the above technical problems, the present application provides a battery manufacturing process, aiming to improve the cycle performance of the battery.

[0088] The battery manufacturing process includes: obtaining a battery to be processed, injecting liquid into the battery; and charging the battery before sodium in the battery is reduced at the negative electrode.

[0089] In the prior art, water is generally removed from the battery by high-temperature baking. However, this water removal method is difficult to effectively remove water from the battery.

[0090] The present application adopts a charging method to remove water. Specifically, a battery to be processed is obtained; the battery is injected with liquid. Considering the presence of water in the electrode and the diaphragm, the battery is injected with liquid so that the electrolyte infiltrates the electrode and the diaphragm, and the moisture in the electrode and the diaphragm is infiltrated into the electrolyte to facilitate the subsequent removal of water.

[0091] For sodium batteries, sodium ions will first be reduced on the current collector before the additive begins to form a film on the negative electrode. It is understood that the reduction of sodium to sodium metal at the negative electrode can include sodium being reduced to sodium metal on the negative electrode surface, or it can also include the situation where sodium metal is embedded in the negative electrode (for example, when the negative electrode includes a negative electrode active material, sodium metal is embedded in the layered negative electrode active material). The reduced sodium metal is highly active and easily reacts violently with water in the battery to generate gases such as H2, resulting in a large amount of capacity loss.

[0092] In order to solve the above problems, the present application adopts the method of charging the battery before the sodium in the battery is reduced at the negative electrode. During the charging process of the battery, water can receive electrons at the negative electrode to undergo a reduction reaction, producing hydrogen and hydroxide, or water can decompose in the electrolyte to generate hydrogen ions, which receive electrons at the negative electrode to undergo a reduction reaction, producing hydrogen. In this way, the water in the battery is removed. After the water is removed, the sodium is reduced at the negative electrode to generate sodium metal element, reducing the risk of the reduced sodium reacting with the water, alleviating the problem of battery capacity loss, and improving the battery's cycle performance. That is, before sodium reduction occurs at the negative electrode, the water in the battery cell is removed as much as possible, thereby reducing the adverse effects of water on the subsequent operation of the battery cell.

[0093] It is understandable that in the prior art, vacuum baking can be used to remove water, but this method is difficult to effectively remove water from the battery, thereby deteriorating the battery's cycle performance. The vacuum baking method requires two steps: high-temperature baking and high-temperature soaking. The present application continuously removes water from the battery cell by charging the battery at a first charging voltage, thereby improving the battery's cycle performance. At the same time, the present application also omits the two steps of high-temperature baking and high-temperature soaking in the prior art process, thereby improving the battery cell production efficiency.

[0094] In one embodiment, the step of electrochemically removing water from the battery includes: charging the battery at a first charging voltage, the first charging voltage being higher than H + The first charging voltage is lower than the reduction potential of sodium.

[0095] The battery is charged at a first charging voltage, and the first charging voltage is higher than H + The reduction potential of the first charge voltage is lower than the reduction potential of sodium. In this way, water can undergo a reduction reaction at the negative electrode at this charge voltage, and water gains electrons at the negative electrode to generate H2, for example, 2H2O+4e - →H2+2OH - Alternatively, water can react with NaPF6 in the electrolyte to produce hydrogen ions, which receive electrons at the negative electrode and are reduced to H2, for example, 2H2O+NaPF6+4e - →NaPO2F2+2H2+4F - It is understandable that, at the same time, it is difficult for sodium reduction and precipitation to occur at this voltage, that is, it is difficult for sodium to be reduced at the negative electrode.

[0096] In one embodiment, the battery is a sodium battery without a negative electrode system, and the first charging voltage is lower than the deposition potential of sodium; or, the battery is a sodium battery with a negative electrode system, and the first charging voltage is lower than the reduction potential of the electrolyte additive, and the reduction potential range of the electrolyte additive is 1.5V to 2.5V.

[0097] It can be understood that a battery without a negative electrode system means that the negative electrode current collector does not include the negative electrode active material. For example, taking a sodium battery as an example, a battery without a negative electrode system means that the ions in the negative electrode are no longer embedded in the layered material and exist in the form of ions, but form sodium elements directly on the negative electrode current collector.

[0098] A battery with a negative electrode system means that the negative electrode current collector is provided with a negative electrode active material, such as hard carbon and other materials. For example, taking a sodium battery as an example, a battery with a negative electrode system means that ions are embedded in the layered material in the negative electrode and exist in the form of ions.

[0099] It is understandable that the sodium in the negative electrode-free sodium battery is deposited in the negative electrode in the form of a single substance. When the water in the battery is not removed during the sodium deposition process, it not only affects the capacity loss of sodium, but also affects the further deposition of sodium at the negative electrode. It is understandable that if there is still water in the battery before the sodium deposition, the deposited sodium will react violently with the water. The sodium deposited on the negative electrode is unevenly distributed on the surface of the negative electrode. In the subsequent process of further sodium deposition, it cannot be evenly deposited on the negative electrode, thus affecting the further deposition effect of sodium. It is also understandable that the uneven deposition of sodium can easily cause local dendrites, which makes the battery cell prone to short circuit.

[0100] Considering that during the charging process of the battery at the first charging voltage, water can receive electrons at the negative electrode to undergo a reduction reaction to produce hydrogen and hydroxide, or water can decompose in the electrolyte to generate hydrogen ions, and the hydrogen ions receive electrons at the negative electrode to undergo a reduction reaction to produce hydrogen, it is assumed that when the battery is charged at the first charging voltage, the electrolyte additive reacts to participate in the formation of a film at the negative electrode interface. At this time, the film formed at the negative electrode interface will hinder the water or H + Migrate to the negative electrode (for example, when the water migrates from the positive electrode to the negative electrode, the film formed on the negative electrode interface will prevent the water from reaching the negative electrode surface, that is, the film formed on the negative electrode interface makes it difficult for water to receive electrons at the negative electrode). At this time, water or H + Because the film formed at the negative electrode interface is difficult to accept electrons at the negative electrode, the water removal effect is reduced. Therefore, during the charging process at the first charging voltage, the phenomenon of film formation at the negative electrode should be reduced. That is, the first charging voltage is lower than the reduction potential of the electrolyte additive. Specifically, when the battery is a sodium battery with a negative electrode system, the first charging voltage is lower than the reduction potential of the electrolyte additive, and the reduction potential range of the electrolyte additive is 1.5V to 2.5V. For example, in one embodiment, when the reduction potential of the electrolyte additive is 2V, the first charging voltage is lower than 2V. When the first charging voltage is lower than the reduction potential of the electrolyte additive, the phenomenon of the electrolyte additive participating in film formation at the negative electrode can be reduced, and the water removal effect can be improved.

[0101] In one embodiment, the first charging voltage ranges from 1.0V to 2.9V, preferably from 1.7V to 2.9V, and more preferably from 2.5V to 2.7V.

[0102] It can be understood that when the first charging voltage is low, the reduction reaction of water is weak and it is difficult to effectively remove water. When the first charging voltage is high, sodium reduction and precipitation will occur. In order to alleviate the above problems, the range of the first charging voltage is 1.0V to 2.9V, preferably 1.7V to 2.9V, and more preferably 2.5V to 2.7V.

[0103] It can be understood that, considering that when the battery is a sodium battery without a negative electrode system, the first charging voltage is lower than the reduction potential of the electrolyte additive, and the reduction potential range of the electrolyte additive is greater than 2.9V and less than or equal to 3.5V, for the sodium battery without a negative electrode system, at this time, in one embodiment, the range of the first charging voltage can be 1.0V to 2.9V, that is, in actual operation, the appropriate first charging voltage is selected according to the specific battery type and the reduction potential of the additive in the electrolyte.

[0104] When the battery is a sodium battery with a negative electrode system, the first charging voltage is lower than the reduction potential of the electrolyte additive, and the reduction potential range of the electrolyte additive is 1.5V to 2.5V. At this time, in one embodiment, the first charging voltage can be in the range of 1.0V to 1.49V. That is, in actual operation, the appropriate first charging voltage is selected according to the specific battery type and the reduction potential of the additive in the electrolyte.

[0105] In the above-mentioned 1.0V to 2.9V, the values ​​include the minimum and maximum values ​​of the range, and every value between such minimum and maximum values. Specific examples include but are not limited to the point values ​​in the embodiments and 1.0V, 1.2V, 1.3V, 1.4V, 1.5V, 1.6V, 1.7V, 1.8V, 1.9V, 2.0V, 2.1V, 2.2V, 2.3V, 2.4V, 2.5V, 2.6V, 2.7V, 2.8V, 2.9V, etc., as well as the range values ​​between any two of the above-mentioned point values.

[0106] In the above-mentioned 1.7V to 2.9V, the values ​​include the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Specific examples include but are not limited to the point values ​​in the embodiments and 1.7V, 1.8V, 1.9V, 2.0V, 2.1V, 2.2V, 2.3V, 2.4V, 2.5V, 2.6V, 2.7V, 2.8V, 2.9V, etc., as well as the range values ​​between any two of the above-mentioned point values.

[0107] In the above-mentioned 2.5V to 2.7V, the values ​​include the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Specific examples include but are not limited to the point values ​​in the embodiments and 2.5V, 2.55V, 2.6V, 2.65V, 2.7V, etc., as well as the range values ​​between any two of the above-mentioned point values.

[0108] In one embodiment, the step of charging the battery at the first charging voltage further includes heating the battery.

[0109] It can be understood that during the charging process of the battery at the first charging voltage, water can receive electrons at the negative electrode to undergo a reduction reaction to produce hydrogen and hydroxide, or water can decompose in the electrolyte to generate hydrogen ions, which receive electrons at the negative electrode to undergo a reduction reaction to produce hydrogen. When the water or H + When the water is continuously diffused to the negative electrode, the water removal efficiency is improved. In order to effectively diffuse the water in the battery to the negative electrode, for example, to release the water in the electrode, the battery is heated. The battery has an appropriate temperature so that the water in the battery material can be quickly dissolved into the electrolyte phase, that is, the electrolyte fully infiltrates the battery material, so that the water is continuously diffused to the negative electrode side (or the H generated by the hydrolysis of the sodium salt). +Driven by the electric field, it migrates to the negative electrode side. Under the effective voltage, water or H + Continuous reduction on the negative electrode side produces hydrogen, thus improving the water removal effect.

[0110] It is also understandable that, in theory, the battery can be heated before charging at the first charging voltage, so that the moisture in the battery core material is released into the electrolyte in advance.

[0111] In one embodiment, in the step of heating the battery, the temperature of the battery ranges from 25°C to 70°C, preferably from 45°C to 60°C.

[0112] The battery is heated. The water removal effect is best when the battery temperature is between 25°C and 70°C, preferably between 45°C and 60°C. It is understood that the battery temperature should not be too high. Excessive temperature will cause the low-boiling-point additives in the battery to evaporate, causing the battery to swell. Furthermore, when removing hydrogen generated inside the battery during charging, the low-boiling-point additives will be discharged from the battery, resulting in the loss of the low-boiling-point additives and affecting battery performance.

[0113] In the above-mentioned 25℃ to 70℃, the values ​​include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include but are not limited to the point values ​​in the embodiments and 25℃, 27℃, 29℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, etc., as well as the range values ​​between any two of the above-mentioned point values.

[0114] In one embodiment, the process of charging the battery at the first charging voltage further includes evacuating the battery.

[0115] Theoretically, water is reduced to produce H2 during the water removal process. At this time, a pressure difference will be formed inside and outside the battery. When the battery is opened, H2 will be released from the inside of the battery. However, in order to speed up the water removal, the chemical equilibrium reaction is made to proceed towards the reaction product, for example, 2H2O+NaPF6+4e - →NaPO2F2+2H2+4F - The battery maintains a certain vacuum level during the dehydration process, allowing the H2 generated within the cell to be promptly removed. This allows the electrochemical balance to continuously shift towards H2 production, improving the dehydration effect.

[0116] In one embodiment, in the step of evacuating the battery, the vacuum degree inside the battery ranges from greater than or equal to -80 kPa to less than 0 kPa, preferably from -30 kPa to -10 kPa.

[0117] The battery's internal vacuum within the aforementioned range can effectively remove H2. At the same time, the vacuum should not be too high, as excessive vacuum can cause electrolyte loss and loss of low-boiling-point additives. For these reasons, the battery's internal vacuum is set within the aforementioned range.

[0118] Among the above-mentioned values ​​greater than or equal to -80kPa and less than 0kPa, the values ​​include the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Specific examples include but are not limited to the point values ​​in the embodiments and -80kPa, -75kPa, -70kPa, -65kPa, -60kPa, -55kPa, -50kPa, -45kPa, -40kPa, -35kPa, -30kPa, -25kPa, -20kPa, -15kPa, -10kPa, -0.1kPa, etc., as well as the range values ​​between any two of the above-mentioned point values.

[0119] In one embodiment, in the step of charging the battery at the first charging voltage, the charging time is 4 hours to 48 hours, preferably 6 hours to 18 hours.

[0120] It is understandable that as the charging time of the battery at the first charging voltage increases, the water inside the battery is continuously removed. However, when the charging time is further extended, the water removal effect is not obvious. In order to ensure that the water or H + While being removed, the production efficiency and energy consumption are increased to the optimal level. The charging time is 4h to 48h, preferably 6h to 18h. It can be understood that the water removal efficiency is close to 90% in 12h.

[0121] In the above-mentioned 4h to 48h, the values ​​include the minimum and maximum values ​​of the range, and every value between such minimum and maximum values. Specific examples include but are not limited to the point values ​​in the embodiments and 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h, 26h, 28h, 30h, 32h, 34h, 36h, 38h, 40h, 42h, 44h, 46h, 48h, etc., and the range values ​​between any two of the above-mentioned point values.

[0122] In one embodiment, in the step of charging the battery at the first charging voltage, the charging method includes one of constant voltage charging, step voltage charging, and cyclic charging.

[0123] Constant voltage charging means charging at a constant voltage during the charging time. For example, if the charging time is 6 hours, the battery is charged at a constant voltage of 2V during the 6 hours.

[0124] Step voltage charging means changing the voltage during the charging time. For example, if the charging time is 6 hours, the battery is first charged at 2V for 2 hours, then at 2.5V for 2 hours, and then at 2.7V for 2 hours.

[0125] Cyclic charging refers to repeating a charge and discharge cycle multiple times within the charging time. For example, a charge and discharge cycle includes charging at a rate of 0.23C to a voltage of 2.5V, then discharging at a rate of 0.23C to a voltage of 2.0V, and repeating the above charge and discharge process.

[0126] It is understood that the present application prefers a constant voltage charging method, which can of course be cyclic charging within a certain voltage range, or charging in a step voltage rising manner. That is, constant voltage charging is a charging method that maintains a constant voltage at a suitable voltage. For example, in one embodiment, before sodium reduction, the electric field strength in the battery is kept at a maximum (voltage is maximum), and the direction of the electric field is always consistent, thereby ensuring that water or hydrogen ions move directionally from the positive electrode to the negative electrode at the maximum rate. The constant voltage charging method can make the interior of the battery always at the maximum electric field strength, which helps to improve the effect of water removal.

[0127] In one embodiment, the battery comprises a sodium secondary battery.

[0128] The sodium battery in the present application includes but is not limited to sodium secondary batteries.

[0129] In one embodiment, the battery comprises a negative electrode-free sodium secondary battery.

[0130] It is understood that, for a sodium secondary battery without a negative electrode system, a coating can be applied on the current collector to ensure uniform deposition of the metal on the current collector.

[0131] In one embodiment, after charging the battery at the first charging voltage, the method further comprises the following steps: charging the battery at a second charging voltage, wherein the second charging voltage is higher than the reduction potential of sodium and / or higher than the reduction potential of the electrolyte additive.

[0132] It is understood that water removal is performed before sodium reduction, and after water removal, the battery is charged for a second time, and the battery is charged at a second charging voltage, which is higher than the reduction potential of sodium and / or higher than the reduction potential of the electrolyte additive. In this way, sodium is reduced or sodium ions are intercalated into the negative electrode active material, or the additive in the electrolyte forms a film at the negative electrode. It is understood that for a sodium secondary battery with a negative electrode system (the negative electrode includes a negative electrode active material), during the second charging process, the second charging voltage is higher than the reduction potential of the electrolyte additive, which can enable the electrolyte additive to participate in film formation and form protection for the interface; for a sodium secondary battery without a negative electrode system, the second charging voltage is higher than the reduction potential of sodium, so that sodium is effectively deposited at the negative electrode.

[0133] In one embodiment, the second charging voltage is in a range of greater than 2.9V and less than or equal to 4.2V.

[0134] The range value of the second charging voltage satisfies the above range. For sodium secondary batteries without a negative electrode system, sodium deposition can be effectively achieved. For sodium secondary batteries with a negative electrode system, sodium ions can be effectively embedded in the negative electrode active material.

[0135] In the above-mentioned range greater than 2.9V and less than or equal to 4.2V, the values ​​include the minimum and maximum values ​​of the range, and every value between the minimum and maximum values. Specific examples include but are not limited to the point values ​​in the embodiments and 2.95V, 3.0V, 3.1V, 3.2V, 3.3V, 3.4V, 3.5V, 3.6V, 3.7V, 3.8V, 3.9V, 4.0V, 4.1V, 4.2V, etc., as well as the range values ​​between any two of the above-mentioned point values.

[0136] In one embodiment, after the battery is charged at the second charging voltage, the steps of injecting liquid into the battery, evacuating the battery, injecting protective gas, and sealing the battery are further included.

[0137] It can be understood that the charging process of the second charging voltage can be regarded as a formation step. The battery needs to be formed during the preparation process of the battery. There will be electrolyte loss in the formation process (for example, part of the electrolyte is drawn away by negative pressure, and part of the electrolyte is reacted). Therefore, after formation, liquid injection, vacuuming, protective gas injection, and sealing steps are required.

[0138] In one embodiment, the positive electrode active material of the battery includes at least one of Na3MnTi(PO4)3, Na3MnV(PO4)3, Na3TiV(PO4)3, Na3Fe2(PO4)3, and Na3MnZr(PO4)3.

[0139] The positive electrode active material of the battery of the present application includes but is not limited to at least one of Na3MnTi(PO4)3, Na3MnV(PO4)3, Na3TiV(PO4)3, Na3Fe2(PO4)3, and Na3MnZr(PO4)3.

[0140] It is understandable that for battery cells that are difficult to remove moisture from through the "high-temperature baking" process, such as Nasicon-type phosphate positive electrode material system battery cells, moisture can be removed through electrochemical dehydration technology, thereby improving the cycle life of the battery cells and reducing the risk of gas production.

[0141] In one embodiment, the present application also provides a battery processing device, including: a battery acquisition unit, configured to obtain a battery to be processed, wherein the battery is filled with electrolyte; and a charging unit, configured to control the sodium in the battery to charge the battery before the negative electrode is reduced.

[0142] A battery processing device can be used to remove water from the battery. The battery processing device includes a battery acquisition unit and a charging unit. The battery acquisition unit is configured to obtain the battery to be processed, and the battery is filled with electrolyte; the charging unit is configured to control the sodium in the battery to charge the battery before the negative electrode is reduced.

[0143] In one embodiment, the charging unit includes a first charging unit configured to control the battery to be charged at a first charging voltage, the first charging voltage being higher than H + The first charging voltage is lower than the reduction potential of sodium.

[0144] The dehydration unit includes a first charging unit configured to control the battery to be charged at a first charging voltage, the first charging voltage being higher than the H + The first charging voltage is lower than the reduction potential of sodium.

[0145] The battery is charged at a first charging voltage controlled by the first charging unit, and the first charging voltage is higher than H + The first charging voltage is lower than the reduction potential of sodium. Thus, water reduction occurs at this charging voltage. At the same time, sodium reduction precipitation, i.e., sodium reduction at the negative electrode, is less likely to occur at this voltage.

[0146] In one embodiment, the charging unit further includes a heating unit, which is configured to heat the battery in response to the first charging unit controlling the battery to charge at the first charging voltage; and / or, the charging unit further includes a vacuum unit, which is configured to vacuum the battery in response to the first charging unit controlling the battery to charge at the first charging voltage.

[0147] The battery is heated by the heating unit, and the battery has an appropriate temperature, so that the water in the battery material can be quickly dissolved into the electrolyte phase, that is, the electrolyte fully infiltrates the battery material, so that the water continues to diffuse to the negative electrode side (or the H generated by the hydrolysis of sodium salt). + Driven by the electric field, it migrates to the negative electrode side. Under the effective voltage, water or H + Continuous reduction on the negative electrode side produces hydrogen, thus improving the water removal effect.

[0148] The vacuum unit is used to control the vacuum degree inside the battery during the dehydration process, so that the H2 generated in the battery cell can be removed in time, and the electrochemical balance continues to move towards the production of H2, thereby improving the dehydration effect.

[0149] In one embodiment, the present application also provides a battery, including a battery prepared by the above-mentioned battery manufacturing process.

[0150] In one embodiment, the present application further provides an electrical device, which includes the battery as described above.

[0151] This application uses the method of charging and removing water from the battery before the sodium in the battery is reduced at the negative electrode. In this way, after the water is removed, the sodium is reduced at the negative electrode, reducing the risk of the reduced sodium reacting with water, alleviating the problem of battery capacity loss, and improving the battery's cycle performance. In other words, before sodium reduction occurs at the negative electrode, the water in the battery cell is removed as much as possible, thereby reducing the adverse effects of water on the subsequent operation of the battery cell.

[0152] Moreover, through the battery manufacturing process of the present application, the proton hydrogen at the end of the alcohol substance can be reduced to generate H2, thereby improving the battery interface. That is, the battery manufacturing process of the present application can remove the proton hydrogen at the end of the compound containing terminal hydroxyl groups. Specifically, some alcohol substances, such as ethylene glycol, 1,3-butanediol, etc., are added to the pole piece as plasticizers to improve the toughness of the pole piece. However, as these plasticizers accumulate, the problem of increased interface impedance will be caused, thereby worsening the battery performance. The battery manufacturing process of the present application can alleviate the above problems, that is, before the sodium in the battery is reduced at the negative electrode, the battery is charged. During the charging process, the proton hydrogen at the end of the alcohol substance can be reduced to generate H2, thereby alleviating the problem of increased interface impedance caused by these alcohol substances.

[0153] That is, through the battery manufacturing process of the present application, the cycle life of the battery cell can be improved.

[0154] In addition, the battery and the electric device of the present application will be described below with reference to the drawings as appropriate.

[0155] It is understandable that batteries include battery cells, battery modules, and battery packs.

[0156] Figure 2 shows an example battery module 4. Referring to Figure 2 , within the battery module 4, multiple battery cells 5 may be arranged sequentially along the length of the battery module 4. Of course, they may also be arranged in any other manner. Furthermore, the multiple battery cells 5 may be secured together using fasteners.

[0157] Optionally, the battery module 4 may further include a housing having an accommodation space, and the plurality of battery cells 5 are accommodated in the accommodation space.

[0158] 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.

[0159] Figures 3 and 4 illustrate an example battery pack 1. Referring to Figures 3 and 4 , 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 placed 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.

[0160] In addition, the present application also provides an electrical device, which includes at least one of the electrode assembly, battery module, or battery pack provided in the present application. The electrode assembly, battery module, or battery pack can be used as a power source for the electrical device, or as an energy storage unit for the electrical device. The electrical device may include 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.

[0161] As an electrical device, an electrode assembly, battery module or battery pack can be selected according to its usage requirements.

[0162] Figure 5 shows an example of an electric device. This device can be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the electrode assembly, a battery pack or battery module can be used.

[0163] 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 an electrode assembly as a power source.

[0164] Example

[0165] Example 1

[0166] Preparation of positive electrode sheet:

[0167] The positive electrode active material NaFePO4, the conductive agent acetylene black, and the binder carboxymethyl cellulose were fully stirred and mixed in an appropriate amount of N-methylpyrrolidone (NMP) at a mass ratio of 95:2:3 to form a uniform positive electrode slurry; the positive electrode slurry was coated on the surface of the positive electrode current collector aluminum foil, and after drying, cold pressing, and die-cutting, a positive electrode sheet with a thickness of 200 μm was obtained.

[0168] Preparation of negative electrode sheet:

[0169] Conductive carbon and binder carboxymethyl cellulose in a mass ratio of 60:40 are prepared and dissolved in a solvent to obtain a conductive coating slurry. A current collector (copper foil) is prepared and the conductive coating slurry is coated on the current collector. After drying, the coating thickness is 2 μm. The negative electrode sheet is obtained through compaction and other processes.

[0170] Preparation of electrolyte:

[0171] In an argon-filled glove box with a water content of <1 ppm, diethylene glycol dimethyl ether and tetrahydrofuran were mixed in a mass ratio of 1:3, sodium hexafluorophosphate (NaPF6) with a concentration of 1.0 mol / L was added, and the mixture was stirred evenly to obtain an electrolyte.

[0172] Isolation film:

[0173] Polypropylene film as separator

[0174] Battery Assembly:

[0175] The prepared positive electrode sheet, negative electrode sheet, and separator are rolled into bare cells according to the preparation process of wound cells, and then placed into a shell and packaged into a dry cell;

[0176] Battery manufacturing process:

[0177] After the above-mentioned dry cell battery is filled with liquid once, it is directly transferred to the "constant voltage charging" process, and the battery is charged with the first charging voltage (1.0V). During the charging process using the first charging voltage, the battery is also heated, and the battery temperature is 45°C. At the same time, the battery is also vacuumed (the vacuum degree inside the battery is -30kPa), and the charging time is 24h.

[0178] After charging is completed, the battery enters the formation stage. After the formation is completed, the battery is filled with liquid, vacuumed, injected with protective gas, and sealed.

[0179] Example 2 to Example 6

[0180] On the basis of Example 1, the first charging voltage is adjusted to obtain Examples 2 to 6.

[0181] Example 7 and Example 8

[0182] On the basis of Example 4, the temperature of the battery was adjusted to obtain Example 7 and Example 8.

[0183] Example 9 and Example 10

[0184] On the basis of Example 4, the vacuum degree inside the battery was adjusted to obtain Examples 9 and 10.

[0185] Example 11 to Example 14

[0186] On the basis of Example 4, the charging time of the battery at the first charging voltage is adjusted to obtain Examples 11 to 14.

[0187] Comparative Example 1

[0188] The battery was prepared by the same steps as in Example 1, and the prepared battery was dehydrated by "high-temperature baking", that is, the prepared positive electrode sheet, negative electrode sheet, and isolation film were rolled into a bare cell according to the preparation process of the wound cell, and the cell was shelled and packaged into a dry cell; the packaged dry cell was vacuum baked at a temperature of 45°C for 60 hours. After the baking was completed, the electrolyte was injected for the first time, and the electrode liquid was fully infiltrated at a temperature of 45°C for 24 hours. The battery was then formed, the electrolyte was injected again, and the battery was filled with nitrogen, pressed with glue nails, etc. to obtain a battery product.

[0189] Cyclic performance test:

[0190] Five battery cells from each of the aforementioned examples and comparative examples were tested in parallel. Each cell was charged at room temperature at a 0.33C rate to a voltage of 3.65V, then discharged at a 0.33C rate to a voltage of 2.5V. The reversible capacity was measured as C0. This charge and discharge cycle was repeated until the discharge capacity (Cn / C0) at a given cycle was ≤80%. The total number of cycles was recorded as X-Cycle. Cn is the reversible capacity at the nth cycle.

[0191] Table 1 List of Examples

[0192] It can be seen from the experimental data in Table 1 above that, by comparing the embodiments and the comparative examples, the battery manufacturing process of the present application can effectively improve the cycle performance of the battery, and when the first charging voltage is in the range of 2.5V to 2.7V, the cycle performance is improved more significantly.

[0193] The above is only a preferred embodiment of the present application and does not limit the patent scope of the present application. All equivalent structural transformations made based on the contents of the present application specification and drawings, or direct / indirect application in other related technical fields, are included in the patent protection scope of the present application.

Claims

1. A battery manufacturing process, wherein: include: Obtaining a battery to be processed; Filling the battery with liquid; The battery is charged before the sodium in the battery is reduced at the negative electrode.

2. The battery manufacturing process according to claim 1, wherein: The step of charging the battery includes: The battery is charged at a first charging voltage, wherein the first charging voltage is higher than H + The first charging voltage is lower than the reduction potential of sodium.

3. The battery manufacturing process according to claim 1 or 2, wherein: The first charging voltage ranges from 1.0V to 2.9V, preferably from 1.7V to 2.9V, and more preferably from 2.5V to 2.7V.

4. The battery manufacturing process according to claim 2 or 3, wherein: The step of charging the battery at the first charging voltage also includes heating the battery.

5. The battery manufacturing process according to claim 4, wherein: In the step of heating the battery, the temperature of the battery ranges from 25°C to 70°C, preferably from 45°C to 60°C.

6. The battery manufacturing process according to any one of claims 2 to 5, wherein: The process of charging the battery at the first charging voltage also includes evacuating the battery.

7. The battery manufacturing process according to claim 6, wherein: In the step of evacuating the battery, the vacuum degree inside the battery ranges from greater than or equal to -80 kPa to less than 0 kPa, preferably from -30 kPa to -10 kPa.

8. The battery manufacturing process according to any one of claims 2 to 7, wherein: In the step of charging the battery at the first charging voltage, the charging time is 4 hours to 48 hours, preferably 6 hours to 18 hours.

9. The battery manufacturing process according to any one of claims 2 to 8, wherein: After charging the battery at the first charging voltage, the method further comprises the following steps: The battery is charged at a second charging voltage which is higher than the reduction potential of sodium and / or higher than the reduction potential of the electrolyte additive.

10. The battery manufacturing process according to claim 9, wherein: The range value of the second charging voltage is greater than 2.9V and less than or equal to 4.2V.

11. The battery manufacturing process according to any one of claims 2 to 10, wherein: After the battery is charged at the second charging voltage, the method further includes the steps of injecting liquid, evacuating the battery, injecting protective gas, and sealing the battery.

12. A battery processing device, wherein: include: A battery acquisition unit, configured to obtain a battery to be processed, wherein the battery is filled with an electrolyte; The charging unit is configured to control the sodium in the battery to charge the battery before the sodium in the battery is reduced at the negative electrode.

13. The battery processing device according to claim 12, wherein: The charging unit includes a first charging unit, wherein the first charging unit is configured to control the battery to be charged at a first charging voltage, wherein the first charging voltage is higher than H + The first charging voltage is lower than the reduction potential of sodium.

14. The battery processing device according to claim 13, wherein: The charging unit further includes a heating unit, wherein the heating unit is configured to heat the battery in response to the first charging unit controlling the battery to be charged at a first charging voltage; And / or, the charging unit further includes a vacuum unit, and the vacuum unit is configured to evacuate the battery in response to the first charging unit controlling the battery to charge at the first charging voltage.

15. A battery, wherein: A battery comprising a battery prepared by the battery manufacturing process according to any one of claims 1 to 11.

16. An electrical device, wherein: The electric device comprises a battery as claimed in claim 15.

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