Battery manufacturing process, battery processing device, battery and electric equipment

Abstract

The invention relates to the technical field of batteries, in particular to a battery manufacturing process, a battery processing device, a battery and electric equipment.The battery manufacturing process comprises the steps that the battery to be processed is obtained, and liquid injection is conducted on the battery; the battery is charged before sodium in the battery is reduced at the negative electrode. Sodium in the battery is adopted to charge the battery before the negative electrode is reduced, and in the process of charging the battery, water can receive electrons at the negative electrode to generate a reduction reaction to generate hydrogen and hydroxyl, or water is decomposed in electrolyte to generate hydrogen ions, the hydrogen ions can receive electrons at the negative electrode to generate a reduction reaction to generate hydrogen, and the hydrogen ions can receive electrons at the negative electrode to generate hydrogen. Therefore, water in the battery can be removed, after water removal, sodium is reduced at the negative electrode to generate a sodium metal simple substance, the risk that the reduced sodium reacts with water is reduced, the loss of the battery capacity is reduced, and the cycle performance of the battery is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a battery manufacturing process, a battery processing device, a battery and an electrical device. Background Art

[0002] 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.

[0003] 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. Summary of the invention

[0004] The main purpose of the present invention is to provide a battery manufacturing process, aiming to improve the cycle performance of the battery.

[0005] To achieve the above object, the present invention provides a battery manufacturing process, comprising:

[0006] Obtaining a battery to be processed;

[0007] Filling the battery with liquid;

[0008] The battery is charged before the sodium in the battery is reduced at the negative electrode.

[0009] In the prior art, water is generally removed from the battery by high-temperature baking, but this water removal method is difficult to effectively remove water from the battery.

[0010] The present application adopts charging to remove water. Specifically, a battery to be processed is obtained; the battery is injected with liquid. Considering the presence of water in the pole piece and the diaphragm, the battery is injected with liquid so that the electrolyte infiltrates the pole piece and the diaphragm, and the water in the pole piece and the diaphragm is infiltrated into the electrolyte to facilitate the subsequent removal of water.

[0011] For sodium batteries, before the additive begins to form a film on the negative electrode, sodium ions will first be reduced on the current collector. It is understood that the reduction of sodium to sodium metal at the negative electrode may include the reduction of sodium to sodium metal on the surface of the negative electrode, and may also include the situation where the sodium metal is embedded in the negative electrode (for example, when the negative electrode includes a negative electrode active material, the sodium metal is embedded in the layered negative electrode active material). The reduced sodium metal is highly active and easily reacts violently with the water in the battery to generate gases such as H2, thereby causing a large amount of capacity loss.

[0012] In order to solve the above problems, the present application uses the sodium in the battery to charge the battery before the negative electrode is reduced. During the charging process of the battery, water can receive electrons at the negative electrode to undergo a reduction reaction to produce hydrogen and hydroxyl, or water can be decomposed 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. 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, reducing 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.

[0013] Optionally, the step of charging the battery includes:

[0014] 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.

[0015] The battery is charged at a first charging voltage, and the first charging voltage is higher than H + The first charging voltage is lower than the reduction potential of sodium. In this way, water can undergo a reduction reaction at the negative electrode at this charging 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 precipitation to occur at this voltage, that is, it is difficult for sodium to be reduced at the negative electrode.

[0016] 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;

[0017] 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 ranges from 1.5V to 2.5V.

[0018] 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 directly form sodium elements on the negative electrode current collector.

[0019] 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.

[0020] It is understandable that the sodium in the sodium battery without negative electrode system 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, so that the sodium deposited at the negative electrode is unevenly distributed on the surface of the negative electrode, and in the subsequent process of further sodium deposition, it cannot be evenly deposited at 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.

[0021] 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 hydroxyl, 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 film formation 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 migrated from the positive electrode reaches 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 the 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 receive electrons at the negative electrode, the water removal effect becomes worse. For this reason, the phenomenon of film formation at the negative electrode should be reduced during the charging process at the first charging voltage, 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 above-mentioned 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.

[0022] Optionally, the first charging voltage has a range of 1.0V to 2.9V, preferably 1.7V to 2.9V, and preferably 2.5V to 2.7V.

[0023] 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 large, sodium reduction precipitation will occur. In order to avoid the above problems, the range value of the first charging voltage is 1.0V to 2.9V, preferably 1.7V to 2.9V, and further preferably 2.5V to 2.7V.

[0024] 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 value 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.

[0025] 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 of the electrolyte additive ranges from 1.5V to 2.5V. At this time, in one embodiment, the first charging voltage can range from 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.

[0026] Optionally, the step of charging the battery at the first charging voltage further includes heating the battery.

[0027] 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 hydroxyl, 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. + When the water in the battery 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 sheet, 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.

[0028] It can also be understood that, in theory, the battery can be heated before charging the battery at the first charging voltage, so that the moisture in the battery material is released into the electrolyte in advance.

[0029] 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.

[0030] The battery is heated, and the dehydration effect is better when the battery temperature is in the range of 25°C to 70°C, preferably 45°C to 60°C. It is understandable that the battery temperature cannot be too high. If the battery temperature is too high, the low boiling point additive in the battery will evaporate, the battery will swell, and when the hydrogen generated inside the battery during the charging process is removed, the low boiling point additive will be discharged from the battery, resulting in the loss of the low boiling point additive and affecting the battery performance.

[0031] Optionally, the process of charging the battery at the first charging voltage further includes evacuating the battery.

[0032] 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 in the direction of the reaction product, for example, 2H2O+NaPF6+4e - →NaPO2F2+2H2+4F - , the H2 is quickly discharged by vacuuming, which speeds up the water removal process. That is, the battery maintains a certain vacuum degree in the water removal process, so that the H2 generated in the battery cell is promptly removed, and the electrochemical balance continues to move in the direction of H2 generation, thereby improving the water removal effect.

[0033] Optionally, 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.

[0034] The vacuum degree inside the battery is within the above range, which can effectively remove the H2 inside the battery. At the same time, the vacuum degree cannot be too large. If the vacuum degree inside the battery is too large, it will cause the loss of electrolyte. At the same time, too large a vacuum degree will also cause the loss of low-boiling point additives. Considering all factors, the vacuum degree inside the battery is set within the above range.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] Step voltage charging means charging by 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.

[0040] 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.

[0041] It is understandable that the present application prefers constant voltage charging, and of course it can also 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 (maximum voltage), 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 keep the electric field strength inside the battery at the maximum at all times, which helps to improve the effect of water removal.

[0042] Optionally, after charging the battery at the first charging voltage, the method further comprises the following steps:

[0043] 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.

[0044] It is understandable that water is removed before sodium reduction, and after water removal, the battery is charged for the second time, and the battery is charged at a second charging voltage, and the second charging voltage 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 embedded in the negative electrode active material, or the additive in the electrolyte forms a film at the negative electrode. It is understandable 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 make the electrolyte additive participate in film formation and protect 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.

[0045] Optionally, the second charging voltage has a range of greater than 2.9V and less than or equal to 4.2V.

[0046] The range value of the second charging voltage satisfies the above range. For a sodium secondary battery without a negative electrode system, sodium deposition can be effectively achieved. For a sodium secondary battery with a negative electrode system, sodium ions can be effectively embedded in the negative electrode active material.

[0047] 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 protective gas, and sealing the battery.

[0048] 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 the formation, liquid injection, vacuuming, protective gas injection and sealing steps are required.

[0049] 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.

[0050] 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.

[0051] 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 increasing the cycle life of the battery cells and reducing the risk of gas production.

[0052] The present application also provides a battery processing device, comprising:

[0053] A battery acquisition unit, configured to obtain a battery to be processed, wherein the battery is filled with an electrolyte;

[0054] 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.

[0055] 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.

[0056] 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.

[0057] The charging unit includes a first charging unit, the first charging unit is configured to control the battery to be charged at a first charging voltage, the first charging voltage is higher than H + The reduction potential of the first charging voltage is lower than the deposition potential of sodium.

[0058] 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 deposition potential of sodium, so that the water reduction reaction occurs at the charging voltage. At the same time, the phenomenon of sodium reduction precipitation is difficult to occur at this voltage.

[0059] Optionally, the charging unit further comprises 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 the first charging voltage;

[0060] 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.

[0061] 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 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.

[0062] 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 direction of H2 production, thereby improving the dehydration effect.

[0063] The present application also provides a battery, including a battery prepared by the battery manufacturing process as described above.

[0064] The present application also provides an electrical device, which includes the battery as described above.

[0065] The present application uses the sodium in the battery to charge and remove water before the negative electrode is reduced. 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. That is, before the negative electrode undergoes sodium reduction, the water in the battery cell is removed as much as possible, thereby reducing the adverse effect of water on the subsequent operation of the battery cell.

[0066] Moreover, through the battery manufacturing process of the present application, the proton hydrogen at the end of the alcohol substance can also 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, but with the accumulation of these plasticizers, the problem of increased interface impedance will be caused, thereby deteriorating 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, alleviating the problem of increased interface impedance caused by these alcohol substances.

[0067] That is, through the battery manufacturing process of the present application, the cycle life of the battery cell can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0069] Figure 1 A schematic diagram of the battery manufacturing process for this application;

[0070] Figure 2is a schematic diagram of a battery module provided in an embodiment of the present application;

[0071] Figure 3 is a schematic diagram of a battery pack provided in an embodiment of the present application;

[0072] Figure 4 yes Figure 3 An exploded view of a battery pack provided in an embodiment of the present application is shown;

[0073] Figure 5 It is a schematic diagram of an electrical device using a secondary battery provided in an embodiment of the present application as a power source.

[0074] Description of Figure Numbers:

[0075] Label name Label name 1 Battery Pack 3 Lower box 2 Upper box 4 Battery Module 5 Battery Cell

[0076] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0077] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0078] Below, the battery manufacturing process, battery processing device, battery and electrical equipment of the present application are described in detail 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 structures 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 description 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.

[0079] "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.

[0080] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] The battery manufacturing process includes: obtaining a battery to be processed, injecting liquid into the battery; and charging the battery before the sodium in the battery is reduced at the negative electrode.

[0087] In the prior art, water is generally removed from the battery by high-temperature baking, but this water removal method is difficult to effectively remove water from the battery.

[0088] The present application adopts charging to remove water. Specifically, a battery to be processed is obtained; the battery is injected with liquid. Considering the presence of water in the pole piece and the diaphragm, the battery is injected with liquid so that the electrolyte infiltrates the pole piece and the diaphragm, and the water in the pole piece and the diaphragm is infiltrated into the electrolyte to facilitate the subsequent removal of water.

[0089] For sodium batteries, before the additives begin to form a film on the negative electrode, sodium ions will first be reduced on the current collector. It is understood that the reduction of sodium to sodium metal at the negative electrode may include the reduction of sodium to sodium metal on the surface of the negative electrode, or the embedding of sodium metal into the negative electrode (for example, when the negative electrode includes a negative electrode active material, the sodium metal is embedded in the layered negative electrode active material). The reduced sodium metal is highly active and easily reacts violently with the water in the battery to generate gases such as H2, thereby causing a large amount of capacity loss.

[0090] In order to solve the above problems, the present application uses the sodium in the battery to charge the battery before the negative electrode is reduced. During the charging process of the battery, water can receive electrons at the negative electrode to undergo a reduction reaction to produce hydrogen and hydroxyl, or water can be decomposed 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. 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, reducing 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.

[0091] It is understandable that in the prior art, the water removal method can be vacuum baking, but this water removal method is difficult to effectively remove the moisture in the battery, thereby deteriorating the battery's cycle performance. The water removal method using vacuum baking needs to include two steps: high-temperature baking and high-temperature soaking. The present application charges the battery at the first charging voltage to continuously remove the moisture in the battery cell, 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.

[0092] 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.

[0093] The battery is charged at a first charging voltage, and the first charging voltage is higher than H + The first charging voltage is lower than the reduction potential of sodium. In this way, water can undergo a reduction reaction at the negative electrode at this charging 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 precipitation to occur at this voltage, that is, it is difficult for sodium to be reduced at the negative electrode.

[0094] 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 of the electrolyte additive ranges from 1.5V to 2.5V.

[0095] 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 directly form sodium elements on the negative electrode current collector.

[0096] 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.

[0097] It is understandable that the sodium in the sodium battery without negative electrode system 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, so that the sodium deposited at the negative electrode is unevenly distributed on the surface of the negative electrode, and in the subsequent process of further sodium deposition, it cannot be evenly deposited at 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.

[0098] 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 hydroxyl, 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 film formation 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 migrated from the positive electrode reaches 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 the 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 receive electrons at the negative electrode, the water removal effect becomes worse. For this reason, the phenomenon of film formation at the negative electrode should be reduced during the charging process at the first charging voltage, 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 above-mentioned 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.

[0099] 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.

[0100] 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 large, sodium reduction precipitation will occur. In order to alleviate the above problems, the range value of the first charging voltage is 1.0V to 2.9V, preferably 1.7V to 2.9V, and further preferably 2.5V to 2.7V.

[0101] 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 value 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.

[0102] 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 of the electrolyte additive ranges from 1.5V to 2.5V. At this time, in one embodiment, the first charging voltage can range from 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.

[0103] In the above-mentioned 1.0V to 2.9V, 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 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., and the range value between any two of the above-mentioned point values.

[0104] In the above-mentioned 1.7V to 2.9V, 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 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., and the range values ​​between any two of the above-mentioned point values.

[0105] In the above 2.5V to 2.7V, 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 2.5V, 2.55V, 2.6V, 2.65V, 2.7V, etc., and the range values ​​between any two of the above point values.

[0106] In one embodiment, the step of charging the battery at the first charging voltage further includes heating the battery.

[0107] 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 hydroxyl, 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. + When the water in the battery 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 sheet, 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.

[0108] It can also be understood that, in theory, the battery can be heated before charging at the first charging voltage, so that the moisture in the battery material is released into the electrolyte in advance.

[0109] 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.

[0110] The battery is heated, and the dehydration effect is better when the battery temperature is in the range of 25°C to 70°C, preferably 45°C to 60°C. It is understandable that the battery temperature cannot be too high. If the battery temperature is too high, the low boiling point additive in the battery will evaporate, the battery will swell, and when the hydrogen generated inside the battery during the charging process is removed, the low boiling point additive will be discharged from the battery, resulting in the loss of the low boiling point additive and affecting the battery performance.

[0111] In the above-mentioned 25℃ to 70℃, 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 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.

[0112] In one embodiment, the process of charging the battery at the first charging voltage further includes evacuating the battery.

[0113] 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 in the direction of the reaction product, for example, 2H2O+NaPF6+4e - →NaPO2F2+2H2+4F - , the H2 is quickly discharged by vacuuming, which speeds up the water removal process. That is, the battery maintains a certain vacuum degree in the water removal process, so that the H2 generated in the battery cell is promptly removed, and the electrochemical balance continues to move in the direction of H2 generation, thereby improving the water removal effect.

[0114] 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.

[0115] The vacuum degree inside the battery is within the above range, which can effectively remove the H2 inside the battery. At the same time, the vacuum degree cannot be too large. If the vacuum degree inside the battery is too large, it will cause the loss of electrolyte. At the same time, too large a vacuum degree will also cause the loss of low-boiling point additives. Considering all factors, the vacuum degree inside the battery is set within the above range.

[0116] Among the above-mentioned greater than or equal to -80kPa and less than 0kPa, 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 -80kPa, -75kPa, -70kPa, -65kPa, -60kPa, -55kPa, -50kPa, -45kPa, -40kPa, -35kPa, -30kPa, -25kPa, -20kPa, -15kPa, -10kPa, -0.1kPa, etc., and the range values ​​between any two of the above-mentioned point values.

[0117] 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.

[0118] 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.

[0119] In the above 4h to 48h, 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 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 point values.

[0120] 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.

[0121] 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.

[0122] Step voltage charging means charging by 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.

[0123] 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.

[0124] It is understandable that the present application prefers constant voltage charging, and of course it can also 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 (maximum voltage), 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 keep the electric field strength inside the battery at the maximum at all times, which helps to improve the effect of water removal.

[0125] In one embodiment, the battery comprises a sodium secondary battery.

[0126] The sodium battery in the present application includes but is not limited to a sodium secondary battery.

[0127] In one embodiment, the battery comprises a negative electrode-free sodium secondary battery.

[0128] It can be understood that, for a sodium secondary battery without a negative electrode system, a coating can be applied on the current collector to allow the metal to be uniformly deposited on the current collector.

[0129] 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.

[0130] It is understandable that water is removed before sodium reduction, and after water removal, the battery is charged for the second time, and the battery is charged at a second charging voltage, and the second charging voltage 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 embedded in the negative electrode active material, or the additive in the electrolyte forms a film at the negative electrode. It is understandable 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 make the electrolyte additive participate in film formation and protect 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.

[0131] In one embodiment, the second charging voltage is in a range of greater than 2.9V and less than or equal to 4.2V.

[0132] The range value of the second charging voltage satisfies the above range. For a sodium secondary battery without a negative electrode system, sodium deposition can be effectively achieved. For a sodium secondary battery with a negative electrode system, sodium ions can be effectively embedded in the negative electrode active material.

[0133] Among the above-mentioned values ​​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., and the range value between any two of the above-mentioned point values.

[0134] 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 also included.

[0135] 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 the formation, liquid injection, vacuuming, protective gas injection and sealing steps are required.

[0136] 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.

[0137] 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.

[0138] 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 increasing the cycle life of the battery cells and reducing the risk of gas production.

[0139] 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.

[0140] 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.

[0141] In one embodiment, the charging unit includes a first charging unit, the first charging unit is 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.

[0142] The dehydration unit includes a first charging unit, which is 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.

[0143] 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, the reduction reaction of water occurs at the charging voltage. At the same time, it is difficult for sodium reduction precipitation to occur at this voltage, that is, it is difficult for sodium to be reduced at the negative electrode.

[0144] 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.

[0145] 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 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.

[0146] 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 direction of H2 production, thereby improving the dehydration effect.

[0147] In one embodiment, the present application also provides a battery, including a battery prepared by the battery manufacturing process as described above.

[0148] In one embodiment, the present application further provides an electrical device, which includes the battery as described above.

[0149] The present application uses the sodium in the battery to charge and remove water before the negative electrode is reduced. 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. That is, before the negative electrode undergoes sodium reduction, the water in the battery cell is removed as much as possible, thereby reducing the adverse effect of water on the subsequent operation of the battery cell.

[0150] Moreover, through the battery manufacturing process of the present application, the proton hydrogen at the end of the alcohol substance can also 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, but with the accumulation of these plasticizers, the problem of increased interface impedance will be caused, thereby deteriorating 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, alleviating the problem of increased interface impedance caused by these alcohol substances.

[0151] That is, through the battery manufacturing process of the present application, the cycle life of the battery cell can be improved.

[0152] In addition, the battery and the electric device of the present application will be described below with reference to the drawings as appropriate.

[0153] It can be understood that the battery includes battery cells, battery modules, and battery packs.

[0154] Figure 2 4 is an example of a battery module. Figure 2 In the battery module 4, the plurality of battery cells 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 battery cells 5 may be fixed by fasteners.

[0155] Optionally, the battery module 4 may further include a housing having a receiving space, and the plurality of battery cells 5 are received in the receiving space.

[0156] 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.

[0157] Figure 3 and Figure 4 1 is a battery pack 1 as an example. Figure 3 and Figure 4 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.

[0158] 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 are not limited thereto.

[0159] As an electrical device, an electrode assembly, a battery module or a battery pack can be selected according to its usage requirements.

[0160] Figure 5 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 high power and high energy density requirements of the power consumption device for the electrode assembly, a battery pack or a battery module can be used.

[0161] As another example, the device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is usually required to be light and thin, and an electrode assembly may be used as a power source.

[0162] Example

[0163] Example 1

[0164] Preparation of positive electrode:

[0165] The positive electrode active material NaFePO4, the conductive agent acetylene black, and the binder carboxymethyl cellulose are fully stirred and mixed in a proper amount of N-methylpyrrolidone (NMP) at a mass ratio of 95:2:3 to form a uniform positive electrode slurry; the positive electrode slurry is 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 is obtained.

[0166] Preparation of negative electrode sheet:

[0167] 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, and the negative electrode sheet is obtained through compaction and other processes.

[0168] Preparation of electrolyte:

[0169] 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 after stirring evenly, an electrolyte was obtained.

[0170] Isolation film:

[0171] Polypropylene film as separator

[0172] Battery Assembly:

[0173] 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 put into shells and packaged into dry cells;

[0174] Battery manufacturing process:

[0175] After the above-mentioned dry battery is injected with liquid once, it is directly transferred to the "constant voltage charging" process, and the battery is charged with a first charging voltage (1.0V). The charging process with the first charging voltage also includes heating the battery, and the battery temperature is 45°C. At the same time, the battery is evacuated (the vacuum degree inside the battery is -30kPa), and the charging time is 24h.

[0176] After charging, the battery enters the formation stage. After the formation is completed, the battery is filled with liquid, vacuumed, injected with protective gas, and sealed.

[0177] Example 2 to Example 6

[0178] On the basis of Example 1, the first charging voltage is adjusted to obtain Examples 2 to 6.

[0179] Example 7 and Example 8

[0180] On the basis of Example 4, the temperature of the battery was adjusted to obtain Example 7 and Example 8.

[0181] Example 9 and Example 10

[0182] On the basis of Example 4, the vacuum degree inside the battery was adjusted to obtain Examples 9 and 10.

[0183] Example 11 to Example 14

[0184] 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.

[0185] Comparative Example 1

[0186] The battery is prepared by the same steps as in Example 1, and the prepared battery is dehydrated by "high temperature baking", that is, the prepared positive electrode plate, negative electrode plate, and isolation film are rolled into a bare battery cell according to the preparation process of the wound battery cell, and the battery cell is shelled and packaged into a dry battery cell; the packaged dry battery cell is vacuum baked at a temperature of 45°C for 60 hours. After the baking, the electrolyte is injected for the first time, and the electrode liquid is fully infiltrated at a temperature of 45°C for 24 hours. The battery is then formed, the electrolyte is injected again, and the battery is then filled with nitrogen, glued, etc. to obtain a battery product.

[0187] Cycle performance test:

[0188] Five battery cells in the above embodiments and comparative examples were respectively tested in parallel. Each battery cell was charged at a rate of 0.33C to a voltage of 3.65V at room temperature, and then discharged at a rate of 0.33C to a voltage of 2.5V. The reversible capacity was measured as C0. The charging and discharging were repeated until the discharge capacity of a certain cycle Cn / C0≤80%. The total number of cycles was recorded as X-Cycle. Among them, Cn is the reversible capacity at the nth cycle.

[0189] Table 1 List of Examples

[0190]

[0191]

[0192] It can be seen from the experimental data in Table 1 above that, by comparing the embodiments and 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 are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

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

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

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