Battery and curing method thereof

Abstract

The present application provides a battery and a curing method thereof, wherein the battery includes a battery shell provided with a liquid injection port, the liquid injection port being used to evacuate the interior of the battery shell or inject electrolyte into the battery shell, wherein the method includes: obtaining a gas production rate of the electrolyte that changes with time at a preset curing temperature; determining a preset vacuum pressure relative to the external air pressure when the battery shell reaches a preset deformation degree; determining a vacuum pressure range of the battery shell at the preset deformation degree based on the preset vacuum pressure and the gas production rate; and performing a vacuum operation on the battery according to a pressure within the vacuum pressure range during the battery curing process until the battery curing is completed.

Description

Technical Field

[0001] The present application relates to the technical field of battery preparation, and in particular to a battery and a curing method thereof. Background Art

[0002] In the prior art, polymer electrolyte batteries are prepared by in-situ curing, which is mainly carried out by free radical thermal polymerization, which will cause gas to be generated in the electrolyte. If the exhaust is not timely and thorough, it will seriously affect the electrode contact and hinder ion conduction. Flexible bags can be used to provide battery cell accommodation space and gas accommodation space, and the battery cells can be activated and then placed in the battery square shell to solve the expansion problem caused by electrolyte gas production, but the process is complicated and increases the cost of consumables. It is also possible to maintain a negative pressure inside the battery reactor through a vacuum pipe, and to start the injection pipe from the bottom of the battery reactor under the action of the pressure difference to reduce the electrolyte wall and bubble generation, but it can only discharge the naturally retained gas inside the battery cell during the injection process, and cannot solve the gas production problem during the polymer electrolyte curing process. Summary of the Invention

[0003] In view of this, the purpose of the present application is to at least provide a battery and a curing method thereof, by determining the gas production rate of the electrolyte that changes with time at a preset curing temperature and the preset vacuum pressure relative to the external air pressure that can cause the battery shell to reach a preset deformation degree, thereby determining the vacuum pressure range that causes the battery shell to be in a preset deformation degree according to the preset vacuum pressure and gas production rate, and then, according to the vacuum pressure range, performing a vacuum operation on the battery during the curing process to discharge the gas generated by the electrolyte during the curing process of the battery, thereby solving the technical problem in the prior art that the gas produced by the electrolyte during the curing of the battery cannot be discharged in time, and achieving the technical effect of reducing battery defects.

[0004] This application mainly includes the following aspects:

[0005] In a first aspect, an embodiment of the present application provides a battery curing method, wherein the battery includes a battery shell provided with a liquid injection port, and the liquid injection port is used to evacuate the interior of the battery shell or inject electrolyte into the battery shell, wherein the method includes: obtaining the gas production rate of the electrolyte that changes with time at a preset curing temperature; determining a preset vacuum pressure relative to the external air pressure when the battery shell reaches a preset deformation degree; determining the vacuum pressure range of the battery shell under the preset deformation degree based on the preset vacuum pressure and the gas production rate; and performing a vacuum operation on the battery according to the pressure in the vacuum pressure range during the battery curing process until the battery curing is completed.

[0006] Optionally, the preset vacuum pressure relative to the external air pressure when the battery shell reaches a preset deformation degree is determined in the following manner: determining the initial thickness value of the preset position of the battery shell; performing a vacuum operation on the battery shell and applying different vacuum pressures to determine the actual thickness values of the preset positions corresponding to different vacuum pressures; and determining the preset vacuum pressure relative to the external air pressure when the preset deformation degree is reached based on the actual thickness values and the initial thickness values corresponding to different vacuum pressures.

[0007] Optionally, the vacuum pressure range of the battery shell under a preset deformation degree is determined by: determining the time-varying gas production pressure of the electrolyte according to the time-varying gas production rate; and determining the vacuum pressure range based on the preset vacuum pressure and the time-varying gas production pressure.

[0008] Optionally, determining the time-varying gas production pressure of the electrolyte according to the time-varying gas production rate includes: calculating the gas production pressure based on the ideal gas state equation through the void volume in the battery shell, the ideal gas constant, the battery temperature and the amount of substance converted by the gas production rate.

[0009] Optionally, the battery is vacuumed in the following manner: the battery curing process is divided into multiple curing time periods according to the gas production rate that changes with time; for each curing time period, the battery shell is vacuumed for the curing time period according to the target pressure within the vacuum pressure range corresponding to the curing time period.

[0010] Optionally, after the battery is solidified, the method further includes: sealing the liquid injection port for the first time and controlling the battery temperature to cool to a preset cooling temperature, and performing a formation operation on the battery; after canceling the first seal of the liquid injection port, vacuuming the battery according to a preset exhaust pressure, and the preset exhaust pressure is used to control the interior of the battery to approach a theoretical vacuum environment; and sealing the liquid injection port for a second time to complete the battery packaging.

[0011] Optionally, before the battery is solidified, the method further comprises: placing the battery cell into the battery casing, injecting electrolyte through the injection port, and controlling the liquid level of the electrolyte to be higher than the height of the battery cell.

[0012] Optionally, the method further includes: adjusting the values of multiple curing time periods, and / or target pressures corresponding to multiple curing time periods, and / or preset cooling temperatures corresponding to multiple curing time periods to determine battery process parameters corresponding to different values, wherein the battery process parameters are used to measure battery defects; and selecting target values of multiple curing time periods and / or preset cooling temperatures for reducing battery defects according to the battery process parameters under different values.

[0013] Optionally, the battery process parameters include electrolyte change parameters, battery internal resistance, battery capacity change caused by a preset number of charge and discharge cycles, and the number of cell bubbles; wherein the electrolyte change parameters are used to describe the weight change parameters of the electrolyte before solidification and after formation.

[0014] In a second aspect, an embodiment of the present application further provides a battery, comprising a battery housing provided with a liquid injection port, an electrolyte, and a battery cell, wherein the battery is cured by the battery curing method described in the first aspect or any possible embodiment of the first aspect.

[0015] An embodiment of the present application provides a battery and a curing method thereof, wherein the battery includes a battery shell provided with a liquid injection port, the liquid injection port being used to evacuate the interior of the battery shell or inject electrolyte into the battery shell, wherein the method includes: obtaining the gas production rate of the electrolyte that changes with time at a preset curing temperature; determining a preset vacuum pressure relative to the external air pressure when the battery shell reaches a preset deformation degree; determining a vacuum pressure range of the battery shell when it is at a preset deformation degree based on the preset vacuum pressure and the gas production rate; and performing a vacuum operation on the battery according to the pressure within the vacuum pressure range during the battery curing process until the battery curing is completed. By determining the gas production rate of the electrolyte that changes with time at a preset curing temperature and the preset vacuum pressure relative to the external air pressure that can cause the battery shell to reach a preset deformation degree, the vacuum pressure range that causes the battery shell to be at a preset deformation degree is determined according to the preset vacuum pressure and gas production rate. Then, the battery is vacuumed during the battery curing process according to the vacuum pressure range to discharge the gas generated by the electrolyte during the battery curing process, which solves the technical problem in the prior art that the gas produced by the electrolyte during battery curing cannot be discharged in time, and achieves the technical effect of reducing battery defects.

[0016] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 A schematic structural diagram of a battery provided in an embodiment of the present application is shown.

[0019] Figure 2 A flow chart of a battery curing method provided in an embodiment of the present application is shown.

[0020] Figure 3 A side view of a battery provided by an embodiment of the present application is shown Figure 1 .

[0021] Figure 4 A side view of a battery provided by an embodiment of the present application is shown Figure 2 . DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. It should be understood that the drawings in the present application only serve the purpose of illustration and description and are not used to limit the scope of protection of the present application. In addition, it should be understood that the schematic drawings are not drawn to scale. The flowcharts used in this application illustrate the operations implemented according to some embodiments of the present application. It should be understood that the operations of the flowcharts can be implemented out of sequence, and steps without logical context can be reversed or implemented simultaneously. In addition, those skilled in the art, under the guidance of the contents of this application, can add one or more other operations to the flowchart, or remove one or more operations from the flowchart.

[0023] In addition, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application generally described and shown in the drawings here can be arranged and designed in various configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present application.

[0024] Batteries, as chemical energy storage devices, are widely used in consumer electronics, energy storage power stations, power batteries, and other fields due to their advantages such as high specific energy, long service life, and no memory effect. As the capacity and energy density of single cells increase, batteries need to be connected in series or parallel to increase specifications, and battery safety issues are becoming increasingly serious. Solid-state batteries are considered an important solution to battery safety issues due to their characteristics such as electrolyte non-leakage and non-flammability. In the existing technology, polymer electrolytes prepared by in-situ curing methods are preferred for battery applications with high specific energy and high safety requirements due to their advantages such as good electrode interface and high manufacturability. In-situ curing methods are mainly carried out by free radical thermal polymerization, which is accompanied by gas generation. If the exhaust is not timely and thorough, it will seriously affect the electrode contact, hinder ion conduction, and cause battery defects. Square-shell batteries are widely used due to their efficient system assembly rate. However, when designing square-shell battery cells, the thickness of the battery cell before entering the shell is usually smaller than the internal thickness of the square shell due to the expansion of the battery electrodes during charging and discharging. The ratio of the battery cell thickness to the internal thickness of the square shell is usually 90-95%. However, due to the certain rigidity of the shell itself, the in-situ cured polymer electrolyte solid-state battery cannot effectively pressurize the battery cell body on the one hand. On the other hand, it will swell and deform as the internal air pressure changes. If the vacuum degree is too high, the middle part of the shell will be compressed and deformed, and the liquid level inside the battery cell will rise. As the curing proceeds, the fluidity of the polymer electrolyte decreases, and the gas generated is not easy to be discharged. On the other hand, the electrolyte is squeezed to the upper edge and solidified, and cannot return to between the electrodes, forming an invalid electrolyte, which affects the uniformity of the electrode interface and reduces the electrical performance.

[0025] At present, the gas inside the soft-pack battery cell can be discharged by clamping it with external pressure, or the soft-pack battery cell can be degassed by adjusting the bayonet, vacuum extraction, and heat sealing processes. The above two methods are both for the manufacture of flexible shell battery cells, and cannot be used for corresponding extrusion of square hard shell batteries. Furthermore, the existing technology will consider providing battery cell accommodating space and gas accommodating space by means of flexible bags, activating the battery cell, taking out the battery cell and then putting it into the square shell. This method can solve the gas production and expansion problems, but the process is complicated and increases the cost of consumables. Alternatively, the battery reactor is kept at a negative pressure through a vacuum pipe, and the injection pipe is ordered to start injection from the bottom of the battery reactor under the action of the pressure difference, thereby reducing the electrolyte wall adhesion and bubble generation, but the injection is only for the discharge of the naturally retained gas inside the battery cell during the injection process, and cannot solve the gas production problem during the solidification process of the polymer electrolyte.

[0026] Based on this, an embodiment of the present application provides a battery and a curing method thereof. By determining the gas production rate of the electrolyte that varies with time at a preset curing temperature and the preset vacuum pressure relative to the external air pressure that can cause the battery shell to reach a preset deformation degree, the vacuum pressure range that causes the battery shell to be at a preset deformation degree is determined according to the preset vacuum pressure and gas production rate. Then, according to the vacuum pressure range, the battery is vacuumed during the battery curing process to discharge the gas generated by the electrolyte during the battery curing process. This solves the technical problem in the prior art that the gas produced by the electrolyte during battery curing cannot be discharged in time, and achieves the technical effect of reducing battery defects, as follows:

[0027] See also Figure 1 , Figure 1 This is a schematic diagram of the structure of a battery provided in an embodiment of the present application. Figure 1 As shown, the battery provided in the embodiment of the present application includes a positive electrode post 101, a negative electrode post 102, a battery housing 104 provided with a liquid injection port 103, an electrolyte 106, and a battery cell 105. The positive electrode post 101 and the negative electrode post 102 are led out of the battery housing 104. The liquid injection port is used to evacuate the interior of the battery housing or inject electrolyte into the battery housing.

[0028] Exemplarily, the electrolyte injected through the injection port is selected as a polymer electrolyte, and the initiator of the polymer electrolyte includes but is not limited to one or more of the following: azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, azoisobutyric acid cyanamide, and the monomer of the polymer electrolyte includes but is not limited to one or more of the following: tetraethylene glycol dimethyl ether, polyethylene glycol dimethacrylate, acrylate, pentaerythritol tetraacrylate.

[0029] Exemplarily, the positive electrode of the battery cell includes but is not limited to one or more of the following: lithium iron phosphate, lithium manganese iron phosphate, lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium-rich manganese, and lithium nickel manganese oxide; the negative electrode includes but is not limited to one or more of the following: graphite, lithium titanate, hard carbon, silicon carbon, silicon oxygen carbon, silicon, and metallic lithium.

[0030] For example, the monomer of the polymer electrolyte selected in the embodiment of the present application is tetraethylene glycol dimethyl ether (5% by weight), the initiator of thermal polymerization is azobisisobutyronitrile (1% by weight), the lithium salt is lithium hexafluorophosphate at a concentration of 1 mol / L, and the solvent is ethylene carbonate, wherein the weight ratio of methyl ethyl carbonate is 3:7.

[0031] See also Figure 2 , Figure 2 This is a flow chart of a battery curing method provided in an embodiment of the present application. Figure 2As shown, the curing method of the battery provided in the embodiment of the present application includes the following steps:

[0032] S101: Obtaining a gas production rate of the electrolyte that changes with time at a preset curing temperature.

[0033] The preset curing temperature refers to the ideal temperature of the battery under control during the curing process of the battery. For example, the preset curing temperature is 60°C.

[0034] That is, before injecting the electrolyte into the battery case, the electrolyte is heated to 60°C and the outgassing volume of the electrolyte is measured over time. The time-varying gas production rate is then determined by the ratio of the time-varying outgassing volume to time. Furthermore, when determining the time-varying gas production rate, the mass of the electrolyte should be set to the same as the mass of the electrolyte actually injected into the battery case to ensure the accuracy of the gas production rate.

[0035] For example, in the embodiment of the present application, the weight of the electrolyte injected into the battery shell is 230 grams. Then, 230 grams of electrolyte is prepared and the electrolyte is controlled to maintain at 60°C. It is found that the change in gas production rate is mainly divided into three stages. The gas production rate in the first 30 minutes is 3 mL / min (milliliters per minute), the gas production rate from 30 to 90 minutes is 4.8 mL / min, and the gas production rate after 90 minutes is 0.6 mL / min.

[0036] For example, the gas discharged from the electrolyte can be collected by a sealed collection tank, and the gas production rate that changes with time can be calculated by the change in pressure in the collection tank over time. This application does not limit the method for calculating the gas production rate of the electrolyte at a preset curing temperature.

[0037] S102: Determine a preset vacuum pressure relative to the external air pressure when the battery housing reaches a preset deformation degree.

[0038] Exemplarily, the preset deformation degree refers to the preset thickness change degree of the battery shell at a preset position, and the battery shell should not cause deformation of the battery cell when it reaches the preset deformation degree. Furthermore, even if the battery shell is controlled to be at the preset deformation degree during the curing process, it will not affect the battery cell body.

[0039] In other words, because the thickness of the battery cell itself is less than the width of the inner wall of the battery case, and the reduction in the width of the inner wall of the battery case due to the preset degree of deformation does not affect the thickness of the battery cell, the battery cell can be placed in the battery case to determine the preset vacuum pressure relative to the external air pressure when the battery case reaches the preset degree of deformation. Alternatively, the preset vacuum pressure relative to the external air pressure when the battery case reaches the preset degree of deformation can be determined without placing the battery cell. This application does not impose any restrictions on this.

[0040] Among them, the preset vacuum pressure relative to the external air pressure when the battery shell reaches a preset deformation degree is determined in the following manner: determining the initial thickness value of the preset position of the battery shell; performing a vacuum operation on the battery shell and applying different vacuum pressures to determine the actual thickness values of the preset positions corresponding to different vacuum pressures; and determining the preset vacuum pressure relative to the external air pressure when the preset deformation degree is reached based on the actual thickness values and the initial thickness values corresponding to different vacuum pressures.

[0041] That is to say, the initial thickness value refers to the thickness value of the preset position of the battery shell when the battery shell is not vacuumed, and the vacuum pressure refers to the difference between the pressure inside the battery shell and the pressure outside the battery shell, or the difference between the pressure inside the battery shell and the atmospheric pressure.

[0042] Furthermore, when the battery case is vacuumed through the liquid injection port, the pressure outside the battery case is greater than the pressure inside the battery case, causing the battery case to deform inward. As the absolute value of the vacuum pressure gradually increases, the pressure inside the battery case gradually decreases, which in turn causes the thickness value at the preset position to gradually decrease. Therefore, the actual thickness values of the preset positions corresponding to different vacuum pressures can be collected. Then, for different vacuum pressures, the ratio of the actual thickness value of the preset position corresponding to the vacuum pressure to the initial thickness value is used as the deformation ratio of the battery case, and the vacuum pressure corresponding to the deformation ratio of the preset deformation degree is used as the preset vacuum pressure.

[0043] For example, the preset position refers to the center of the battery casing, and the preset deformation degree refers to a 99% deformation ratio at the center of the battery casing, meaning that the thickness of the center of the battery casing decreases by 1%. This change in thickness at the center does not squeeze the battery cells. Furthermore, it is believed that even if the battery casing deforms to the preset deformation degree, it can subsequently return to its original shape.

[0044] See also Figure 3 and Figure 4 , Figure 3 A side view of a battery provided in an embodiment of the present application Figure 1 , Figure 4 A side view of a battery provided in an embodiment of the present application Figure 2 .like Figure 3 As shown, the thickness d1 of the battery cell 105 is less than the thickness d2 of the middle position of the battery shell 104. The middle position of the battery shell may be the position where half of the height of the battery shell is located. Figure 4As shown, when the battery housing 104 is vacuumed, the battery housing 104 will be recessed, but the battery cells 105 will not be squeezed. Furthermore, during the vacuuming operation, the thickness of the middle portion of the battery housing 104 at different vacuuming pressures is measured to determine the preset vacuuming pressure corresponding to the preset degree of deformation. For example, the preset vacuuming pressure is -80,000 Pa (Pa), meaning that the internal pressure of the battery housing 104 is 80,000 Pa lower than the external pressure, or in other words, the internal pressure of the battery housing 104 is 80,000 Pa lower than atmospheric pressure.

[0045] return Figure 2 S103: Determine a vacuum pressure range of the battery housing under a preset deformation degree according to the preset vacuum pressure and the gas production rate.

[0046] That is to say, in order to fully exhaust the electrolyte during the battery curing process to reduce battery defects, the present application also performs a vacuum operation on the battery shell during the battery curing process. The exhaust of the electrolyte during the battery curing process will affect the pressure inside the battery shell, causing the pressure inside the battery shell to change. Therefore, it is necessary to consider the pressure change inside the battery shell caused by the exhaust of the electrolyte under the preset vacuum pressure, so that even if the electrolyte generates gas during the curing process, the battery shell continues to be in a preset deformation degree. The deformation of the battery shell at the preset deformation degree is conducive to the full exhaust of the electrolyte, solving the technical problem in the prior art that the electrolyte cannot be fully exhausted during the curing process.

[0047] Among them, the vacuum pressure range of the battery shell under a preset deformation degree is determined by the following method: determining the time-varying gas production pressure of the electrolyte according to the time-varying gas production rate; determining the vacuum pressure range based on the preset vacuum pressure and the time-varying gas production pressure.

[0048] Specifically, determining the time-varying gas production pressure of the electrolyte according to the time-varying gas production rate includes: calculating the gas production pressure based on the ideal gas state equation through the void volume in the battery shell, the ideal gas constant, the battery temperature and the amount of substance converted by the gas production rate.

[0049] For example, the battery case of the present application has a remaining void volume of 37 ml after placing the battery cell and injecting 230 grams of electrolyte, and the gas production rate of the electrolyte is 3 mL / min (ml per minute) within 30 minutes, 4.8 mL / min from 30 to 90 minutes, and 0.6 mL / min after 90 minutes. That is, the maximum gas production rate is 4.8 mL / min and the minimum gas production rate is 0.6 mL / min. Considering that the volume of 1 mol of gas under standard conditions is 22400 mL, the amount of substance produced per minute converted according to the maximum gas production rate per minute is 4.8 / 22400=0.000214 mol, and the amount of substance produced per minute converted according to the minimum gas production rate per minute is 0.6 / 22400=0.0000267 mol.

[0050] Among them, the ideal gas state equation is:

[0051] (1)

[0052] In formula (1), It refers to the pressure, Refers to the gas volume, in this application the void volume is 37 ml, is the amount of substance, is the ideal gas constant, which is 8.314 J / (mol·K). is the battery temperature in Kelvin.

[0053] Furthermore, due to the degassing of the electrolyte, the pressure inside the battery case changes, and the maximum gas production pressure inside the battery case per minute is , the minimum gas production pressure in the battery shell per minute To convert volume from milliliters to cubic meters, you need to multiply by The temperature of 273.15 (Kelvin) was chosen because actual operation is significantly affected by equipment and processes, and actual on-site temperatures may vary slightly. Therefore, an ideal temperature standard was chosen for calculation. In fact, the temperature here can also be calculated based on the Kelvin temperature of the battery temperature measured in the actual environment or the Kelvin temperature of the preset curing temperature. Furthermore, even if the electrolyte in the battery casing generates gas, causing the pressure inside the battery casing to increase, in order to control the deformation of the battery casing to maintain the preset deformation degree, it is necessary to increase the vacuum strength inside the battery casing. Therefore, the vacuum pressure at the minimum gas production pressure should be -80,000 - 1639 = -81,639 Pa, and the vacuum pressure at the maximum gas production pressure should be -80,000 - 13,135 = -93,135 Pa. Theoretically, the vacuum pressure range is [-93,135 Pa, -81,639 Pa]. In other words, vacuuming the battery casing within the vacuum pressure range can maintain the preset deformation degree.

[0054] For example, the vacuum pressure in different time periods is calculated based on the change rule that the gas production rate of the electrolyte is 3mL / min (milliliters per minute) within 30 minutes, 4.8mL / min from 30 to 90 minutes, and 0.6mL / min after 90 minutes. The vacuum pressure per minute within 30 minutes should be -80000-8220=-88220Pa, and the exhaust pressure per minute from 30 minutes to 90 minutes should be , the vacuum pressure per minute from 30 minutes to 90 minutes should be -80000-13135=-913135Pa, and the exhaust pressure per minute after 90 minutes should be , after 90 minutes, the vacuum pressure per minute should be -80000-1639=-81639Pa.

[0055] S104: During the battery curing process, the battery is vacuumed at a pressure within the vacuuming pressure range until the battery is cured.

[0056] The battery is vacuumed in the following manner: the battery curing process is divided into a plurality of curing time periods according to the gas production rate that changes with time; for each curing time period, the battery shell is vacuumed in the curing time period according to the target pressure within the vacuum pressure range corresponding to the curing time period.

[0057] Specifically, the first curing period is the first 30 minutes of the curing process, the second curing period is from 30 to 90 minutes into the curing process, and the third curing period is from 90 to 120 minutes into the curing process. Each curing period corresponds to a target pressure within the vacuum pressure range. Furthermore, for each curing period, the battery housing is vacuumed at the target pressure corresponding to that curing period to maintain the battery housing deformation within the preset range. Therefore, throughout the curing process, the battery housing maintains the preset deformation, and the inward concave deformation of the battery housing facilitates the expulsion of gases during the electrolyte curing process. Furthermore, while the internal volume of the battery housing remains relatively unchanged, the pressure increase caused by the gases generated during the curing process and the pressure reduction caused by the vacuuming are relatively balanced, thereby relatively minimizing compression deformation in the central portion of the housing. Furthermore, maintaining the preset deformation allows the housing to recover after venting is complete, potentially allowing less electrolyte to be squeezed onto the upper edge. Since electrolyte addition typically provides a 3-5% excess, this generally does not affect battery performance.

[0058] Before the battery is solidified, the method further includes: placing the battery core into the battery housing, injecting electrolyte through the injection port, and controlling the liquid level of the electrolyte to be higher than the height of the battery core.

[0059] That is to say, before curing the battery, the battery cell and the electrolyte need to be placed in the battery case to perform the battery curing operation. For example, a dry battery cell at room temperature is placed in the battery case, and then 230 grams of polymer electrolyte precursor is injected into the battery case through the injection port. Figure 1 The electrolyte level h2 should be higher than the cell body height h1, and the battery should be left in a static state for 24 hours before curing. During the curing process, the battery temperature is maintained at the preset curing temperature, and the battery housing is vacuumed to the corresponding target pressure according to different curing time periods until the electrolyte solidifies into a non-fluid state, and the battery is fully cured.

[0060] After the battery is solidified, the method further includes: sealing the liquid injection port for the first time and controlling the battery temperature to cool to a preset cooling temperature, and performing a formation operation on the battery; after canceling the first seal of the liquid injection port, vacuuming the battery according to a preset exhaust pressure, and the preset exhaust pressure is used to control the interior of the battery to approach a theoretical vacuum environment; and sealing the liquid injection port for the second time to complete the battery packaging.

[0061] Exemplarily, the preset cooling temperature can be set to room temperature. Furthermore, after the battery is solidified, the liquid injection port is temporarily sealed by means of a nail, and the battery temperature is left to cool to room temperature, and then the battery is charged and discharged at a constant current of 0.1C to realize the formation operation of the battery. During the formation process, the battery core will expand, that is, the thickness of the battery core moves in the direction of fitting the inner wall of the battery shell. During the charging process, lithium ions are released from the positive electrode and embedded in the negative electrode material. The volume of the negative electrode material will expand, thereby increasing the thickness of the battery core. By performing charging activation, an interface film is formed on the electrode to ensure the stable transmission of subsequent lithium ions. Then, the formed battery core is vacuum degassed, the temporary seal of the liquid injection port is cancelled, and the battery shell is vacuumed to a preset exhaust pressure of -95000Pa, and maintained for 30s. Finally, the liquid injection port is vacuum-sealed and welded, and the insulating film is coated and shaped to complete the battery packaging.

[0062] Exemplarily, the method further includes: adjusting the values of multiple curing time periods, and / or target pressures corresponding to multiple curing time periods, and / or preset cooling temperatures corresponding to multiple curing time periods to determine battery process parameters corresponding to different values, wherein the battery process parameters are used to measure battery defects; and selecting target values of multiple curing time periods and / or preset cooling temperatures for reducing battery defects according to the battery process parameters under different values.

[0063] Specifically, the battery process parameters include electrolyte change parameters, battery internal resistance, battery capacity change caused by a preset number of charge and discharge cycles, and the number of bubbles in the battery cells; wherein the electrolyte change parameters are used to describe the weight change parameters of the electrolyte before solidification and after formation.

[0064] Exemplarily, the electrolyte change parameter includes the electrolyte change amount, or the electrolyte weight loss ratio. Therefore, by calculating the difference between the weight of the first battery after the electrolyte is injected into the battery casing and before the battery is solidified and the weight of the second battery after the battery is formed, the difference is used as the electrolyte change amount or the ratio of the difference to the first battery weight is used as the electrolyte weight loss ratio, and the electrolyte change amount or the electrolyte weight loss ratio is used as the electrolyte change parameter. The internal resistance of the battery can be the internal resistance tested by a resistance meter after the battery is secondary packaged. The preset number of charge and discharge cycles can be to select 100 charge and discharge cycles, calculate the battery capacity after 100 charge and discharge cycles and compare it with the battery capacity after one charge and discharge operation, and use the ratio as the battery capacity change caused by the preset number of charge and discharge cycles. The number of bubbles in the battery cell refers to disassembling the battery after 100 charge and discharge cycles and recording the number of bubbles.

[0065] Exemplarily, the duration of each curing time period can be modified, and / or the vacuum pressure of each curing time period can be modified, and / or the battery temperature of each curing time period can be modified. And each time a parameter is modified, the battery's electrolyte change parameters, battery internal resistance, battery capacity change caused by a preset number of charge and discharge cycles, and the number of cell bubbles can be statistically analyzed. By comparing the electrolyte change parameters, battery internal resistance, battery capacity change caused by a preset number of charge and discharge cycles, and the number of cell bubbles, the duration of each curing time period, vacuum pressure, and battery temperature under the condition of optimal battery quality can be determined. Furthermore, the battery can be actually prepared according to the duration of each curing time period, vacuum pressure, and battery temperature under the condition of optimal battery quality to improve the battery quality.

[0066] Furthermore, Table 1 refers to a numerical table of battery process parameters under different value conditions.

[0067] Table 1:

[0068]

[0069] That is to say, Example 1 refers to setting the first curing time period t1 to the first 30 minutes of the curing process, and controlling the vacuum pressure P1 within the first curing time period t1 to -88163Pa, the second curing time period t2 to 30 minutes to 90 minutes of the curing process, and controlling the vacuum pressure P2 within the second curing time period t2 to -93135Pa, the third curing time period t3 to 90 minutes of the curing process, and controlling the vacuum pressure P3 within the third curing time period t3 to -81639Pa, that is, the total time taken for the entire curing process is 120 minutes. In addition, the battery temperature is controlled to 60°C throughout the curing process. In this way, the electrolyte change parameters, battery internal resistance, battery capacity change caused by a preset number of charge and discharge cycles, and the number of cell bubbles of the battery made by curing the battery according to the above parameters are calculated. Furthermore, Examples 2 to 8 modify the values of the curing time periods to determine the values of the corresponding battery process parameters, and Example 9 modifies the battery temperature during the third curing time period to determine the values of the corresponding battery process parameters. Comparative Example 1 does not vacuum the curing process, and Comparative Examples 2 to 4 control the vacuum pressures of each curing time period to be equal. Furthermore, according to Table 1, it can be found that by setting different curing time periods according to the exhaust rate and correspondingly setting the vacuum pressure to prepare the battery in the manner of Example 1, the battery electrolyte weight loss can be controlled to be relatively small, the internal resistance to be small, the number of cell bubbles to be small, and the cell capacity retention rate to be high after 100 charge and discharge cycles, effectively improving the battery quality and reducing the battery bubble defects.

[0070] Based on the same application concept, the embodiments of the present application also provide a battery corresponding to the battery curing method provided in the above embodiments. Since the principle of solving the problem by the battery in the embodiments of the present application is similar to the battery curing method in the above embodiments of the present application, the implementation of the battery can refer to the implementation of the method, and the repeated parts will not be repeated.

[0071] The present application also provides a battery in an embodiment, comprising a battery housing with a liquid injection port, an electrolyte, and a battery cell. The battery is cured using the battery curing method described in the above embodiment. The cured battery is then subjected to formation, vacuum degassing, and secondary packaging molding to complete the battery.

[0072] Furthermore, based on the gas production of the polymer electrolyte during the curing process and taking into account the deformation strength of the battery shell, combined with the influence of the curing temperature on the gas volume and pressure, the vacuum pressure in different curing time periods during the curing process is designed, and the battery is vacuumed through the battery's injection port to apply negative pressure to the inside of the battery to balance the pressure changes inside the battery cell, ensure that the shell has no significant deformation and reduce internal gas residue, solve the problems of battery cell expansion and battery defects caused by high-temperature curing gas production of polymer electrolytes, improve the distribution uniformity and interface consistency of the in-situ cured electrolyte, and effectively improve battery performance.

[0073] Those skilled in the art can clearly understand that, for the convenience and simplicity of description, the specific working process of the system and device described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here. In the several embodiments provided in this application, it should be understood that the disclosed system, device and method can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0074] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0075] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0076] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a non-volatile computer-readable storage medium that is executable by a processor. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0077] The above are only specific embodiments of the present application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A battery curing method, characterized in that: The battery includes a battery housing provided with a liquid injection port, wherein the liquid injection port is used to evacuate the interior of the battery housing or inject electrolyte into the battery housing. The method comprises: Obtaining a gas production rate of the electrolyte that changes with time at a preset curing temperature; determining a preset vacuum pressure relative to the external air pressure when the battery housing reaches a preset deformation degree; Determining a vacuum pressure range for the battery housing at a preset degree of deformation based on the preset vacuum pressure and the gas production rate, wherein the preset degree of deformation is the degree of deformation at which the battery housing returns to its original shape after curing is completed; During the battery curing process, the battery is vacuumed at a pressure within the vacuuming pressure range, and the battery housing is controlled to be continuously at the preset deformation degree during the curing process until the battery is cured.

2. The method according to claim 1, characterized in that The preset vacuum pressure relative to the external air pressure when the battery housing reaches a preset deformation degree is determined by the following method: Determining an initial thickness value of the battery housing at a preset position; Performing a vacuum operation on the battery housing and applying different vacuum pressures to determine actual thickness values of the preset positions corresponding to the different vacuum pressures; The preset vacuum pressure relative to the external air pressure when the preset deformation degree is reached is determined according to the actual thickness value and the initial thickness value corresponding to different vacuum pressures.

3. The method according to claim 1, characterized in that The vacuum pressure range of the battery housing under a preset deformation degree is determined by: According to the gas production rate that changes with time, the gas production pressure of the electrolyte that changes with time is determined; The vacuuming pressure range is determined based on the preset vacuuming pressure and the gas production pressure that changes with time.

4. The method according to claim 3, characterized in that Determining the time-varying gas production pressure of the electrolyte according to the time-varying gas production rate includes: The gas production pressure is calculated based on an ideal gas state equation by the void volume in the battery housing, the ideal gas constant, the battery temperature, and the amount of substance converted by the gas production rate.

5. The method according to claim 1, wherein The battery is vacuumed in the following manner: The battery curing process is divided into multiple curing time periods according to the gas production rate that changes with time; For each curing time period, the battery housing is vacuumed according to a target pressure within the vacuuming pressure range corresponding to the curing time period.

6. The method according to claim 1, characterized in that After the battery is cured, the method further includes: The liquid injection port is sealed for the first time and the battery temperature is controlled to cool to a preset cooling temperature, and a formation operation is performed on the battery; After the initial seal of the liquid injection port is removed, the battery is evacuated according to a preset exhaust pressure, wherein the preset exhaust pressure is used to control the interior of the battery to approach a theoretical vacuum environment; The liquid injection port is sealed for the second time to complete the battery packaging.

7. The method according to claim 6, characterized in that Before the battery is cured, the method further comprises: The battery cell is placed in the battery housing, and then the electrolyte is injected through the injection port, and the liquid level of the electrolyte is controlled to be higher than the height of the battery cell.

8. The method according to claim 6 or 7, characterized in that The method further comprises: Adjusting the values of multiple curing time periods, and / or target pressures corresponding to the multiple curing time periods, and / or preset cooling temperatures corresponding to the multiple curing time periods to determine battery process parameters corresponding to different values, wherein the battery process parameters are used to measure battery defects; According to the battery process parameters at different values, target values of multiple solidification time periods and / or preset cooling temperatures for reducing battery defects are selected.

9. The method according to claim 8, characterized in that The battery process parameters include electrolyte change parameters, battery internal resistance, battery capacity change caused by a preset number of charge and discharge cycles, and the number of bubbles in the battery cell; The electrolyte change parameter is used to describe the weight change parameter of the electrolyte before solidification and after formation.

10. A battery, characterized in that: The battery comprises a battery shell provided with a liquid injection port, an electrolyte and a battery cell. Wherein, the battery is cured by the battery curing method according to any one of claims 1 to 9.

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