Method and apparatus for measuring electrolyte wettability rate

Abstract

The embodiment of the present application provides a method and device for measuring the infiltration rate of electrolyte, which can effectively determine the infiltration degree of electrolyte to the electrode sheet by measuring the infiltration rate of electrolyte. The method comprises the following steps: preparing a first cavity, and determining the reference volume and reference pressure of the first cavity; preparing a second cavity; placing an electrode assembly in the second cavity and injecting electrolyte, so that the electrode assembly is infiltrated in the electrolyte; connecting the first cavity with the second cavity, and determining the equilibrium pressure, which is the pressure when the air pressure between the second cavity and the first cavity is balanced; determining the target volume according to the reference volume, the reference pressure and the equilibrium pressure, the target volume being the volume of the space in the second cavity except the electrode assembly and not infiltrated by the electrolyte; and determining the infiltration rate of the electrolyte according to the target volume.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery measurement, in particular to a method and device for measuring electrolyte infiltration rate. BACKGROUND

[0002] Energy saving and emission reduction is the key to the sustainable development of the automobile industry. In this case, electric vehicles have become an important part of the sustainable development of the automobile industry due to their energy-saving and environmentally friendly advantages. For electric vehicles, battery technology is an important factor for their development.

[0003] In the process of battery production and manufacturing, the electrolyte needs to be left for a period of time after being injected to ensure that the pole piece and the diaphragm are fully infiltrated. If the electrolyte does not fully infiltrate the pole piece and the diaphragm, problems such as lithium precipitation may occur, which greatly deteriorates the safety performance of the battery. If the electrolyte infiltrates the pole piece and the diaphragm for too long, the production cycle of the battery will be prolonged, resulting in an increase in the manufacturing cost of the battery. Therefore, how to effectively determine the infiltration degree of the electrolyte to the pole piece and the diaphragm in the battery is a problem to be solved. SUMMARY

[0004] The embodiments of the present application provide a method and device for measuring electrolyte infiltration rate, which can effectively determine the infiltration degree of the electrolyte to the pole piece and the diaphragm by measuring the infiltration rate of the electrolyte.

[0005] In a first aspect, a method for measuring electrolyte infiltration rate is provided, comprising: preparing a first cavity and determining a reference volume and a reference pressure of the first cavity; preparing a second cavity; placing an electrode assembly in the second cavity and injecting electrolyte to make the electrode assembly infiltrate in the electrolyte; connecting the first cavity and the second cavity and determining an equilibrium pressure, the equilibrium pressure being the pressure when the air pressure between the second cavity and the first cavity is balanced; determining a target volume according to the reference volume, the reference pressure and the equilibrium pressure, the target volume being the volume of the space in the second cavity excluding the electrode assembly that is not infiltrated by the electrolyte; and determining the infiltration rate of the electrolyte according to the target volume.

[0006] The embodiment of the present application can determine the target volume in the space of the second cavity except the electrode assembly which is not infiltrated by the electrolyte by using the principle of conservation of mass, the reference volume and the reference pressure of the prepared first cavity, and the balance pressure between the first cavity and the second cavity. Since the target volume has a correlation with the infiltration rate of the electrolyte, for example, as the electrolyte gradually infiltrates the pole piece and the diaphragm, the target volume gradually increases, then slowly increases, and finally remains basically unchanged, and the corresponding infiltration rate of the electrolyte gradually decreases until it decreases to zero, at which time the electrolyte has been fully infiltrated to the pole piece and the diaphragm. Therefore, the accuracy of determining the infiltration rate of the electrolyte according to the target volume is relatively high. Further, in the process of determining the infiltration rate of the electrolyte in the second cavity, the target volume can be obtained by the first cavity, and the cost is relatively low. In other words, the embodiment of the present application can effectively determine the infiltration rate of the electrolyte at a relatively low cost, so as to judge the infiltration degree of the electrolyte to the pole piece and the diaphragm based on the determined infiltration rate.

[0007] In some possible implementation manners, the first cavity is connected with a first switch, and the reference pressure of the first cavity is determined by opening the first switch to inflate or deflate the first cavity, and closing the first switch and measuring the pressure in the first cavity to obtain the reference pressure.

[0008] In some possible implementation manners, the first cavity and the second cavity are communicated through a connecting pipe, the connecting pipe is provided with a second switch, and the balance pressure is determined by opening the second switch and measuring the pressure after the air pressure between the first cavity and the second cavity is balanced to obtain the balance pressure.

[0009] In some possible implementation manners, the connecting pipe is a hard pipe.

[0010] The above technical solution considers that the connecting pipe may be affected by pressure or other forces in the process of determining the infiltration rate of the electrolyte. Therefore, the connecting pipe is set as a hard pipe, so that the connecting pipe will not expand, break or the like when the connecting pipe is affected by pressure or other forces, thereby improving the efficiency of determining the infiltration rate of the electrolyte.

[0011] In some possible implementation manners, the second cavity is provided with a third switch, and the method further includes opening the third switch to communicate the second cavity with the atmosphere.

[0012] The above technical solution communicates the second cavity with the atmosphere, so that the pressure of the second cavity is the atmospheric pressure. In this way, in the process of determining the target volume, the data processing is relatively simple, and the processing speed can be effectively improved.

[0013] In some possible implementations, the second cavity is a cavity formed by a shell of a battery cell, and an injection hole is further provided on the shell. The electrolyte is injected into the second cavity through the injection hole, and the third switch is connected to the injection hole.

[0014] In the above technical solution, the second cavity is a cavity formed by the battery cell shell used in actual production applications. The electrolyte and electrode assembly to be measured are components that will be actually loaded into the battery cell shell in the future. The connecting tube is connected to the second cavity through the reused liquid injection hole on the shell. There is no need to set up an additional connection port between the connecting tube and the second cavity, nor is there any need to customize a special measurement cavity. This not only reduces the complexity of the measurement method, but also effectively reduces the measurement cost of the measurement method.

[0015] In some possible implementations, the reference pressure and the equilibrium pressure are obtained through a relative pressure sensor, and the relative pressure sensor is connected to the first cavity.

[0016] In the above technical solution, the pressure sensor is set as a relative pressure sensor. Since the pressure in the second cavity is atmospheric pressure, the pressure in the second cavity measured by the relative pressure sensor is 0. This makes data processing relatively simple in the process of calculating the target volume using the principle of conservation of matter, and can effectively improve the processing speed.

[0017] In some possible implementations, the reference pressure and the equilibrium pressure are obtained by an absolute pressure sensor, and the absolute pressure sensor is connected to the first cavity.

[0018] In some possible implementations, the method further includes: determining the electrode pressure in the second cavity; determining the target volume based on the reference volume, the reference pressure and the equilibrium pressure includes: determining the target volume based on the reference volume, the reference pressure, the equilibrium pressure and the electrode pressure.

[0019] In some possible implementations, determining the electrode pressure in the second cavity includes: connecting the first cavity to the atmosphere; and measuring the pressure in the first cavity by the absolute pressure sensor, wherein the pressure measured by the absolute pressure sensor is the electrode pressure.

[0020] In some possible implementation manners, the determining the target volume according to the reference volume, the reference pressure and the equilibrium pressure comprises: determining a plurality of target volumes according to the reference volume, the reference pressure and the equilibrium pressure at different time points; and the determining the infiltration rate of the electrolyte according to the target volume comprises: determining the infiltration rate of the electrolyte according to at least two target volumes in the plurality of target volumes and at least two time points corresponding to the at least two target volumes.

[0021] According to the above technical solution, the target volumes are determined according to the reference volumes, the reference pressures and the equilibrium pressures obtained multiple times, the more the values are, and the more accurate the target volumes obtained are. Further, the infiltration rate of the electrolyte determined according to at least two target volumes in the plurality of target volumes is also more accurate and has higher precision.

[0022] In some possible implementation manners, the reference volume is a fixed value.

[0023] According to the above technical solution, the reference volume is set as a fixed value, that is, the reference volume does not change with changes of external factors, so that the precision of the target volume determined based on the reference volume can be improved.

[0024] In some possible implementation manners, the shell for forming the second cavity is a rigid shell.

[0025] According to the above technical solution, the shell for forming the second cavity is a rigid shell, that is, the second cavity does not expand or shrink with the charging or discharging. In this way, if the target volume needs to be determined according to the volume of the second cavity in the process of determining the target volume, since the volume of the second cavity is fixed because the second cavity does not expand or shrink with the charging or discharging, the precision of the target volume determined according to the volume of the second cavity is higher.

[0026] In a second aspect, a device for measuring an electrolyte infiltration rate is provided, and has the following features. The device includes a measuring device including a first cavity and a gas inlet / outlet for inflating or deflating the first cavity, the first cavity having a reference volume; and a pressure sensor connected to the first cavity for measuring a reference pressure of the first cavity after the first cavity is inflated with the gas, and for measuring an equilibrium pressure between the second cavity and the first cavity after the first cavity is connected to a second cavity containing an electrode assembly and the gas pressure between the first cavity and the second cavity is balanced, the second cavity being infiltrated with the electrolyte; wherein the reference volume, the reference pressure and the equilibrium pressure are used to determine a target volume, the target volume being used to determine the electrolyte infiltration rate, the target volume being a volume of the second cavity excluding the electrode assembly and not infiltrated with the electrolyte.

[0027] In some possible implementations, the measuring device is connected with a first switch, and when the first switch is in an open state, the gas can enter or exit the first cavity through the gas inlet / outlet; and when the first switch is switched from the open state to a closed state, the pressure measured by the pressure sensor is the reference pressure.

[0028] In some possible implementations, the first cavity and the second cavity are connected through a connecting pipe, and the connecting pipe is provided with a second switch; wherein when the second switch is in an open state, the pressure measured by the pressure sensor is the equilibrium pressure.

[0029] In some possible implementations, the connecting pipe is a rigid pipe.

[0030] In some possible implementations, the second cavity is provided with a third switch, and when the third switch is in an open state, the second cavity is connected to the atmosphere.

[0031] In some possible implementations, the second cavity is further provided with a liquid injection hole, the electrolyte is injected into the second cavity through the liquid injection hole, and the third switch is connected to the liquid injection hole.

[0032] In some possible implementations, the pressure sensor is an absolute pressure sensor.

[0033] In some possible implementations, the absolute pressure sensor is further used to measure an electrode pressure in the second cavity; wherein the reference volume, the reference pressure, the equilibrium pressure and the electrode pressure are used to determine the target volume.

[0034] In some possible implementations, the absolute pressure sensor measures the pressure in the first cavity as the atmospheric pressure when the first cavity is in communication with the atmosphere.

[0035] In some possible implementations, the pressure sensor is a relative pressure sensor.

[0036] In some possible implementations, the pressure sensor is configured to measure the reference pressure and the equilibrium pressure multiple times at different time points to obtain multiple target volumes, at least two target volumes of the multiple target volumes, and at least two time points corresponding to the at least two target volumes are used to determine the infiltration rate of the electrolyte.

[0037] In some possible implementations, the reference volume is a fixed value.

[0038] In some possible implementations, the shell for forming the second cavity is a rigid shell. BRIEF DESCRIPTION OF DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be briefly introduced as follows. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort on the basis of the drawings.

[0040] Figure 1 is a schematic diagram of a vehicle according to an embodiment of the present application.

[0041] Figure 2 is a structural schematic diagram of a battery according to an embodiment of the present application.

[0042] Figure 3 is an exploded view of a battery cell according to an embodiment of the present application.

[0043] Figure 4 is a schematic flowchart of a method for measuring an electrolyte infiltration rate according to an embodiment of the present application.

[0044] Figure 5 is a schematic diagram of an electrode before electrolyte infiltration according to an embodiment of the present application.

[0045] Figure 6 is a schematic diagram of an electrode after electrolyte infiltration according to an embodiment of the present application.

[0046] Figure 7 is a schematic diagram of the connection between a device for measuring an electrolyte infiltration rate and an electrode assembly according to an embodiment of the present application.

[0047] Figure 8is a schematic diagram of a target volume measured at different time instants by an embodiment of the present application.

[0048] Figure 9 is a schematic block diagram of a device for measuring the electrolyte infiltration rate according to an embodiment of the present application.

[0049] In the drawings, the figures are not necessarily drawn to scale. DETAILED DESCRIPTION

[0050] The embodiments of the present application will be further described in conjunction with the drawings and embodiments. The detailed description and drawings of the following embodiments are used to exemplarily illustrate the principles of the present application, but cannot be used to limit the scope of the present application, i.e., the present application is not limited to the described embodiments.

[0051] In the description of the present application, it should be noted that, unless otherwise specified, the meaning of "a plurality of" is more than two; the orientation or position relationship indicated by the terms "upper", "lower", "left", "right", "inner", "outer" and the like only for the convenience of describing the present application and simplifying the description, and is not intended to indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" and the like are only for the purpose of description, and cannot be understood as indicating or implying relative importance. "Vertical" is not strictly vertical, but within the allowable range of error. "Parallel" is not strictly parallel, but within the allowable range of error.

[0052] The orientation words appearing in the following description are the directions shown in the drawings, and are not limited to the specific structure of the present application. In the description of the present application, it should be noted that, unless otherwise specified and limited, the terms "mounting", "connection", "connecting" should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be directly connected, or indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0053] In the present application, the term "and / or" is only a description of the association relationship between the associated objects, which means that there can be three kinds of relationships, for example, A and / or B can represent the following three cases: A exists alone, A and B exist together, and B exists alone. In addition, the character " / " in the present application generally represents an "or" relationship between the front and rear associated objects.

[0054] Unless otherwise defined, all technical and scientific terms used in the present application have the same meanings as those commonly understood by one of ordinary skill in the art to which this application belongs; the terms used in the present application, unless defined differently, are used as generally used terms in accordance with the prior art; and the present application is not intended to be limited to the specific embodiments described in the specification of the present application; the terms "comprise" and "have" and any variations thereof in the present application and claims and the above description of drawings are intended to cover the non-exclusive inclusion. The terms "first", "second" and the like in the specification of the present application and claims are used to distinguish different objects, not to describe a specific order or primary and secondary relationship.

[0055] Reference to "an embodiment" in this application means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase that the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive of other embodiments. It is explicitly stated that the described embodiments of the application can be combined with other embodiments.

[0056] Reference to "an embodiment" in this application means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase that the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive of other embodiments. It is explicitly stated that the described embodiments of the application can be combined with other embodiments.

[0057] "Multiple" appearing in the present application means more than two (including two), similarly, "multiple groups" means more than two groups (including two groups), "multiple pieces" means more than two pieces (including two pieces), and "multiple columns" means more than two columns (including two columns).

[0058] In the environment of the automobile industry using traditional energy as power supply, the problem of environmental pollution is becoming more and more serious, and actively developing new energy vehicles can reduce the harm to the environment. New energy vehicles can be pure electric vehicles, hybrid electric vehicles or extended range vehicles, etc.

[0059] Figure 1This is a structural diagram of a vehicle 1 according to one embodiment of the present application, and the vehicle 1 may be a new energy vehicle. A motor 40, a controller 30, and a battery 10 may be provided inside the vehicle 1, and the controller 30 is used to control the battery 10 to power the motor 40. For example, a battery 10 may be provided at the bottom, front, or rear of the vehicle 1. The battery 10 may be used to power the vehicle 1, for example, the battery 10 may be used as an operating power source for the vehicle 1, for the circuit system of the vehicle 1, for example, for the working power requirements during the start-up, navigation, and operation of the vehicle 1. In another embodiment of the present application, the battery 10 may not only be used as an operating power source for the vehicle 1, but may also be used as a driving power source for the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0060] Battery technology is a crucial factor in the development of new energy vehicles. A battery is a single physical module that includes one or more battery cells to provide higher voltage and capacity. For example, the battery referred to in this application may include a battery module or a battery pack. Batteries generally include a housing that encloses one or more battery cells. This housing prevents liquids or other foreign matter from affecting the charging or discharging of the battery cells.

[0061] For example, Figure 2 As shown in FIG. 1 , a schematic diagram of the structure of a battery 10 according to an embodiment of the present application is provided. The battery 10 may include a plurality of battery cells 20. The battery 10 may also include a housing (or cover), the interior of the housing being a hollow structure, and the plurality of battery cells 20 being accommodated in the housing. Figure 2 As shown, the box body may include two parts, referred to herein as a first part 111 and a second part 112, which are buckled together. The shapes of the first part 111 and the second part 112 may be determined according to the shape of the combination of multiple battery cells 20, and the first part 111 and the second part 112 may each have an opening. For example, the first part 111 and the second part 112 may both be hollow cuboids and each have only one open face, the opening of the first part 111 and the opening of the second part 112 are arranged relative to each other, and the first part 111 and the second part 112 are buckled together to form a box body with a closed chamber. The box body may include a bottom plate 112a, a side plate 112b and a beam. Multiple battery cells 20 are connected in parallel, in series, or in a mixed combination and are placed in the box body formed by buckling the first part 111 and the second part 112.

[0062] Optionally, the battery 10 can further include other structures, which are not described herein. For example, the battery 10 can further include a current collecting component for achieving electrical connection between the plurality of battery cells 20, such as parallel connection, series connection or mixed connection. Specifically, the current collecting component can achieve electrical connection between the plurality of battery cells 20 by connecting the electrode terminals of the battery cells 20. Further, the current collecting component can be fixed to the electrode terminals of the battery cells 20 by welding. The electrical energy of the plurality of battery cells 20 can be further led out through the box by a conductive mechanism. Optionally, the conductive mechanism can also belong to the current collecting component.

[0063] The plurality of battery cells 20 included in the battery 10 can be connected in series, in parallel or in mixed connection, which means a mixture of series connection and parallel connection. Optionally, the plurality of battery cells 20 can be connected in series, in parallel or in mixed connection to form a battery module, and the plurality of battery modules can be connected in series, in parallel or in mixed connection to form a battery. That is, the plurality of battery cells 20 can be directly connected to form a battery, or can be connected to form a battery module first, and then the battery module is connected to form a battery.

[0064] According to different power requirements, the number of battery cells 20 can be set to any value. The plurality of battery cells 20 can be connected in series, in parallel or in mixed connection to achieve larger capacity or power.

[0065] Figure 3 A structural schematic diagram of a battery cell 20 according to an embodiment of the present application is shown. The battery cell 20 includes one or more electrode assemblies 22, a housing 211 and a cover plate 212. The housing 211 and the cover plate 212 form an outer shell or a battery box 21. The wall of the housing 211 and the cover plate 212 are both referred to as the wall of the battery cell 20. The shape of the housing 211 is determined according to the shape of the combined one or more electrode assemblies 22. For example, the housing 211 can be a hollow cuboid or a square or a cylinder, and one of the faces of the housing 211 has an opening so that the one or more electrode assemblies 22 can be placed in the housing 211. For example, when the housing 211 is a hollow cuboid or a square, one of the planes of the housing 211 is an opening plane, i.e. the plane does not have a wall so that the inside and outside of the housing 211 are in communication. When the housing 211 can be a hollow cylinder, the end face of the housing 211 is an opening plane, i.e. the end face does not have a wall so that the inside and outside of the housing 211 are in communication. The cover plate 212 covers the opening and is connected with the housing 211 to form a closed cavity for placing the electrode assemblies 22. The housing 211 is filled with electrolyte.

[0066] The battery cell 20 can further include two electrode terminals 214, which can be disposed on the cover plate 212. The cover plate 212 is generally flat, and the two electrode terminals 214 are fixed on the flat surface of the cover plate 212. The two electrode terminals 214 are respectively a positive electrode terminal 214a and a negative electrode terminal 214b. Each electrode terminal 214 is respectively provided with a connecting member 23, which is also referred to as a current collecting member 23, and is located between the cover plate 212 and the electrode assembly 22, so as to electrically connect the electrode assembly 22 and the electrode terminal 214.

[0067] As shown in Figure 3 Each electrode assembly 22 has a first tab 221a and a second tab 222a. The polarities of the first tab 221a and the second tab 222a are opposite. For example, when the first tab 221a is a positive electrode tab, the second tab 222a is a negative electrode tab. The first tab 221a of one or more electrode assemblies 22 is connected to one electrode terminal through one connecting member 23, and the second tab 222a of one or more electrode assemblies 22 is connected to another electrode terminal through another connecting member 23. For example, the positive electrode terminal 214a is connected to the positive electrode tab through one connecting member 23, and the negative electrode terminal 214b is connected to the negative electrode tab through another connecting member 23.

[0068] In the battery cell 20, the electrode assembly 22 can be provided as a single electrode assembly or multiple electrode assemblies according to actual use requirements. Figure 3 As shown in

[0069] The battery cell 20 can further be provided with a pressure relief mechanism 213. The pressure relief mechanism 213 is used to actuate to release the internal pressure or temperature when the internal pressure or temperature of the battery cell 20 reaches a threshold value. The pressure relief mechanism 213 can be various possible pressure relief structures, and the embodiments of the present application are not limited thereto. For example, the pressure relief mechanism 213 can be a temperature-sensitive pressure relief mechanism, which is configured to be able to melt when the internal temperature of the battery cell 20 provided with the pressure relief mechanism 213 reaches a threshold value; and / or the pressure relief mechanism 213 can be a pressure-sensitive pressure relief mechanism, which is configured to be able to break when the internal air pressure of the battery cell 20 provided with the pressure relief mechanism 213 reaches a threshold value.

[0070] The electrode assembly 22 is composed of a positive electrode sheet, a negative electrode sheet and a separator. The battery cell 20 mainly relies on the movement of metal ions between the positive electrode sheet and the negative electrode sheet to work. The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer, the positive electrode active material layer is coated on the surface of the positive electrode current collector, the current collector without the positive electrode active material layer protrudes from the current collector with the positive electrode active material layer, and the current collector without the positive electrode active material layer serves as a positive electrode tab (such as the first tab 221a). Taking a lithium ion battery as an example, the material of the positive electrode current collector can be aluminum, and the positive electrode active material can be lithium cobaltate, lithium iron phosphate, ternary lithium or lithium manganate, etc. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer, the negative electrode active material layer is coated on the surface of the negative electrode current collector, the current collector without the negative electrode active material layer protrudes from the current collector with the negative electrode active material layer, and the current collector without the negative electrode active material layer serves as a negative electrode tab (such as the second tab 222a). The material of the negative electrode current collector can be copper, and the negative electrode active material can be graphite, carbon or silicon, etc. In order to ensure that no fuse occurs when passing a large current, the number of positive electrode tabs is multiple and stacked together, and the number of negative electrode tabs is multiple and stacked together. The material of the separator can be PP or PE, etc. In addition, the electrode assembly can be a winding type structure or a stacking type structure, and the embodiments of the present application are not limited thereto.

[0071] The electrolyte is the carrier of ion transmission in the battery, and plays a role in conducting ions between the positive and negative electrodes. The electrolyte is generally configured by electrolyte lithium salt, organic solvent and additive in proportion. Considering the comprehensive factors such as battery cost and safety performance, the commonly used electrolyte lithium salt at present is lithium hexafluorophosphate (LiPF6). LiPF6 has high electrochemical reliability, room temperature range working requirement and price advantage brought by industrialization scale effect. In addition, lithium bisfluorosulfonylimide salt (LiFSI) and lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) and other electrolyte lithium salts also begin to be applied in the configuration of electrolyte, so as to achieve the purpose of improving the energy density of the battery. Compared with LiPF6, LiFSI has more excellent performance in thermal stability, electrical conductivity, cycle life and low temperature performance.

[0072] The organic solvent is the medium in the electrolyte. The organic solvent generally refers to carbonate solvents. According to the different structures, the carbonate solvents can be divided into cyclic carbonate organic solvents, chain carbonate organic solvents and ether organic solvents. The cyclic carbonate solvents include ethylene carbonate (EC) and propylene carbonate (PC); the chain carbonate solvents include dimethyl carbonate (DMC), diethyl carbonate (DEC) and methyl ethyl carbonate (EMC) and the like. Generally, the electrolyte solvent is mixed and prepared by these carbonate solvents to meet the different battery needs of customers.

[0073] The additives mainly include film-forming additives, high / low temperature additives, flame-retardant additives, and overcharge protection additives. The film-forming additives are the most important additive. Among the other additives, the high / low temperature additives can ensure the stability of the electrolyte in different environments such as high and low temperatures, and have a greater impact on the performance of the automobile in tropical or low-temperature areas. The flame-retardant additives can reduce the risk of battery combustion and explosion, and are more suitable for ternary batteries with poor thermal stability. The overcharge protection additives can protect the positive electrode and prevent the positive electrode structure from being damaged when the battery is overcharged, thereby damaging the cycle performance and affecting the energy density.

[0074] During the operation of the battery, metal ions shuttle between the positive and negative electrodes through the electrolyte. The electrolyte has an important influence on the energy density, cycle life, and safety performance of the battery. For example, if the electrolyte does not fully soak the electrode, it may cause the metal ions to be difficult to insert into the negative electrode, resulting in lithium precipitation and other problems, which seriously affect the safety performance of the battery.

[0075] If the electrolyte is left for too long after being injected into the battery in order to fully soak the electrode, the production cycle of the battery will be prolonged, resulting in an increase in the manufacturing cost of the battery.

[0076] In view of this, the embodiments of the present application propose a method for measuring the soaking rate of the electrolyte, which can effectively determine the soaking degree of the electrolyte on the electrode by measuring the soaking rate of the electrolyte.

[0077] It should be understood that the technical solutions described in the embodiments of the present application are applicable to various devices using batteries, such as mobile phones, portable devices, notebook computers, electric vehicles, electric toys, electric tools, electric vehicles, ships, and spacecraft, such as aircraft, rockets, space shuttles, and spacecraft.

[0078] Figure 4 A schematic flowchart of a method 400 for measuring the soaking rate of the electrolyte is shown. The method 400 can include at least part of the following content.

[0079] 410: Prepare a first cavity and determine the reference volume and reference pressure of the first cavity.

[0080] 420: Prepare a second cavity.

[0081] 430: Place an electrode assembly in the second cavity and inject electrolyte so that the electrode assembly is soaked in the electrolyte.

[0082] 440: Connect the first cavity and the second cavity, and determine the equilibrium pressure, which is the pressure when the air pressure between the second cavity and the first cavity is balanced.

[0083] 450: Determine a target volume based on the reference volume, the reference pressure, and the equilibrium pressure. The target volume is the volume of the space in the second cavity excluding the electrode assembly that is not soaked in the electrolyte.

[0084] 460: Determine the electrolyte infiltration rate based on the target volume.

[0085] In the embodiment of the present application, the target volume of the space in the second cavity excluding the electrode assembly that is not infiltrated with electrolyte is determined by preparing the reference volume and reference pressure of the first cavity and the equilibrium pressure between the first cavity and the second cavity and using the principle of conservation of matter. Since the target volume is correlated with the infiltration rate of the electrolyte, for example, Figure 5 and Figure 6 As shown, as the electrolyte gradually infiltrates the electrode and the diaphragm, the target volume becomes larger and larger. Specifically, as the electrolyte gradually infiltrates the electrode and the diaphragm, the target volume increases rapidly at first, then increases slowly, and finally remains basically unchanged. The corresponding electrolyte infiltration rate gradually decreases until it drops to zero, at which point the electrolyte has fully infiltrated the electrode and the diaphragm. Therefore, the accuracy of determining the electrolyte infiltration rate based on the target volume is high. Furthermore, in the process of determining the electrolyte infiltration rate in the second cavity, the embodiment of the present application can obtain the target volume through the first cavity, and the cost is low. In other words, the embodiment of the present application can effectively determine the electrolyte infiltration rate at a lower cost, and thus judge the degree of electrolyte infiltration of the electrode and the diaphragm based on the determined infiltration rate.

[0086] Optionally, the volume of the first cavity, i.e., the reference volume, can be a fixed value. That is, the reference volume does not change with changes in environmental factors, temperature, air pressure, and the like, and remains a fixed value at any time under any conditions. This improves the accuracy of the target volume determined based on the reference volume.

[0087] Alternatively, during the process of measuring the infiltration rate of the electrolyte, the reference volume may be a fixed value. During other times except the period of measuring the infiltration rate of the electrolyte, the reference volume may be a variable.

[0088] The second cavity is the cavity of the battery cell. Optionally, the housing forming the second cavity can be a rigid housing, i.e., the housing of the battery cell is a rigid housing. In other words, during the charging or discharging process, the second cavity will not expand or contract as the charging or discharging proceeds. For example, the battery of the embodiment of the present application can be a hard-shell battery.

[0089] The shell for forming the second cavity is a rigid shell, that is, the second cavity will not expand or shrink with the charging or discharging. In this way, when determining the target volume, if the target volume needs to be determined according to the volume of the second cavity, since the volume of the second cavity is fixed and will not expand or shrink with the charging or discharging, the accuracy of the target volume determined according to the volume of the second cavity is higher.

[0090] Optionally, the first cavity and the second cavity can be communicated through a connecting pipe. Considering that the connecting pipe may be subjected to pressure or other forces during the determination of the infiltration rate of the electrolyte, the connecting pipe can be a pipe with high strength, for example, a hard pipe. In this technical solution, the connecting pipe is set to a hard pipe, so that when the connecting pipe is subjected to pressure or other forces, the connecting pipe will not expand, break, or the like, thereby improving the efficiency of determining the infiltration rate of the electrolyte.

[0091] When the shell for forming the second cavity is the shell of the battery monomer, the shell of the battery monomer can be provided with a liquid injection hole through which the electrolyte is injected into the second cavity. As shown in Figure 7 , the connecting pipe can be communicated with the second cavity through the liquid injection hole.

[0092] In this technical solution, the second cavity is a cavity formed by the shell of the battery monomer used in actual production and application, and the measured electrolyte and electrode assembly are components that will be actually loaded into the battery monomer shell in the future. The connecting pipe is connected to the second cavity through the multipurpose liquid injection hole on the shell, without the need to additionally set a connecting port of the connecting pipe and the second cavity, or to additionally customize a special cavity for measurement. Not only does this reduce the complexity of the measurement method of the embodiments of the present application, but also effectively reduces the measurement cost.

[0093] Alternatively, the shell of the battery monomer can be further provided with an interface other than the liquid injection hole, and the connecting pipe can be communicated with the second cavity through the other interface.

[0094] Optionally, the connecting pipe and the first cavity, and the connecting pipe and the second cavity can be connected through a sealing material or welding. The sealing material can be, for example, AB glue, rubber, a U-shaped ring, or the like.

[0095] Optionally, the electrode pressure in the second cavity can be atmospheric pressure. For example, referring again to Figure 7 , the second cavity can be provided with a third switch, and at this time, the method 400 can further include: opening the third switch to communicate the second cavity with the atmosphere.

[0096] The third switch can be connected with the liquid injection hole, or the second cavity can be further provided with another interface in addition to the liquid injection hole, and the third switch can be connected to the second cavity through the other interface.

[0097] The technical solution communicates the second cavity with the atmosphere, so that the pressure of the second cavity is atmospheric pressure. In this way, the data processing is simple during the determination of the target volume, and the processing speed can be effectively improved.

[0098] It should be noted that the pressure of the electrode in the second cavity can also not be atmospheric pressure, and the embodiments of the present application do not make specific limitations thereon. For the sake of description, the pressure of the electrode in the second cavity is taken as an example in the following description.

[0099] It should be further noted that, in order to avoid the water vapor and other substances in the atmosphere from entering the second cavity, the second cavity can be communicated with the atmosphere during the determination of the target volume. At other times, the second cavity is not communicated with the atmosphere.

[0100] The implementation of the reference pressure, the equilibrium pressure and the target volume will be described in detail below.

[0101] In some embodiments, as shown in FIG. 1, the first cavity is connected with a first switch. In this case, the reference pressure of the first cavity can be determined by opening the first switch to inflate or deflate the first cavity, then closing the first switch and measuring the pressure in the first cavity to obtain the reference pressure. Figure 7

[0102] Optionally, the gas in the first cavity can be, but is not limited to, an inert gas. For example, helium, argon, etc. Since the inert gas is relatively cheap, filling the inert gas into the first cavity can obtain the reference pressure at a lower cost.

[0103] If the solubility of the gas in the first cavity is high, it means that the gas is easy to dissolve in the electrolyte. In this case, if the gas is dissolved in the electrolyte, the gas will be consumed in the electrolyte in addition to being filled in the first cavity, so that the obtained equilibrium pressure value will be smaller, and the accuracy of the target volume will also be reduced, thereby affecting the accuracy of the determined electrolyte immersion rate.

[0104] Therefore, the solubility of the gas in the first cavity can be less than a threshold value, so that the gas is not dissolved in the electrolyte.

[0105] It should be understood that the specific value of the threshold value can be calculated according to the specific technical requirements or other factors in actual application. For example, the threshold value can be calculated according to the required measurement accuracy.

[0106] ​Optionally, the pressure in the first cavity can be measured by a pressure sensor. The pressure sensor can be connected to the first cavity.

[0107] As an example, the pressure sensor can be a relative pressure sensor. In this example, the electrode pressure in the second cavity measured by the pressure sensor is 0

[0108] As another example, the pressure sensor can be an absolute pressure sensor.

[0109] Since the electrode pressure in the second cavity is atmospheric pressure, in this example, the parameters used to determine the target volume can include, in addition to the reference volume, the reference pressure and the equilibrium pressure, the electrode pressure in the second cavity.

[0110] In an implementation, the first cavity can be connected to the atmosphere, in which case the pressure in the first cavity is also atmospheric pressure. The pressure in the first cavity can be measured by an absolute pressure sensor, and the pressure measured by the absolute pressure sensor is the electrode pressure.

[0111] Specifically, as shown in Figure 7 , a second switch can also be provided on the connecting pipe. The second switch can be opened and the first switch can be closed, i.e., the first cavity is connected to the atmosphere. The pressure can then be measured by the absolute pressure sensor.

[0112] Again, as shown in Figure 7 , the pressure sensor can be provided between the second switch and the first cavity. In an implementation, the pressure sensor can be provided on the connecting pipe.

[0113] In another implementation, the pressure sensor can be provided on other wires or other pipes.

[0114] It should be noted that when the second switch is opened, the third switch is in a closed state.

[0115] In some embodiments, during the measurement of the equilibrium pressure, the second switch can be opened to connect the first cavity and the second cavity. After the air pressure between the first cavity and the second cavity is balanced, the pressure sensor measures the pressure, and the measured pressure is the equilibrium pressure.

[0116] After the first cavity and the second cavity are connected, the air pressure between the first cavity and the second cavity can quickly reach equilibrium. For example, the air pressure between the first cavity and the second cavity can reach equilibrium within 10 seconds.

[0117] It should be understood that the pressure sensor used to measure the reference pressure, the equilibrium pressure and the electrode pressure can be the same pressure sensor or different pressure sensors, and the present application does not make specific limitations thereto.

[0118] It should also be understood that in the embodiments of the present application, "first", "second" and "third" are merely for distinguishing different objects, but do not constitute a limitation on the scope of the embodiments of the present application.

[0119] After the reference volume, the reference pressure and the equilibrium pressure are obtained, the target volume can be determined according to the reference volume, the reference pressure and the equilibrium pressure.

[0120] Specifically, according to the principle of conservation of mass, the following formula can be obtained:

[0121] V1*P1+V2*P2=(V1+V2)*P (1)

[0122] Wherein, V1 is the reference volume, P1 is the reference pressure, V2 is the target volume, P2 is the electrode pressure, and P is the equilibrium pressure.

[0123] If the pressure sensor is an absolute pressure sensor, the target volume V2 satisfies the formula:

[0124]

[0125] If the pressure sensor is a relative pressure sensor, P2 is 0, and the formula (1) can be simplified as:

[0126] V1*P1=(V1+V2)*P (3)

[0127] Then the target volume V2 satisfies the formula:

[0128]

[0129] It can be seen that the pressure sensor is set to a relative pressure sensor, the data processing is simple, and the processing speed can be effectively improved.

[0130] It should be understood that when the reference pressure is determined, the second switch and the third switch can be in a closed state, or the second switch and the third switch can be in an open state and the connecting pipe between the second switch and the third switch is not connected. When the equilibrium pressure is determined, in addition to the second switch being in an open state, the third switch is also in an open state, and the first switch is in a closed state. When the electrode pressure is determined, the connecting pipe between the second switch and the third switch is not connected.

[0131] In the case that the pressure in the second cavity is not atmospheric pressure, the pressure in the second cavity can be measured by Figure 7An additional switch (referred to as the fourth switch) is arranged between the pressure sensor and the first cavity. When determining the reference pressure, the fourth switch can be opened, and the first switch and the second switch can be closed. The pressure measured by the pressure sensor is the reference pressure. When determining the electrode pressure, the fourth switch can be closed, and the second switch and the third switch can be opened. The pressure measured by the pressure sensor is the electrode pressure. When determining the equilibrium pressure, the first switch can be closed, and the second switch, the third switch, and the fourth switch can be opened. The pressure measured by the pressure sensor is the equilibrium pressure.

[0132] Further, the step 450 can specifically include: determining a plurality of target volumes according to the reference volume, the reference pressure, and the equilibrium pressure at different time points.

[0133] As shown in FIG. 6, a corresponding target volume is determined at each of the 31 different time points, so as to obtain a curve of the target volume changing with the infiltration time. Figure 8 As shown in FIG. 6, a corresponding target volume is determined at each of the 31 different time points, so as to obtain a curve of the target volume changing with the infiltration time. Figure 8 As shown in FIG. 6, a corresponding target volume is determined at each of the 31 different time points, so as to obtain a curve of the target volume changing with the infiltration time.

[0134] Therefore, the step 460 can specifically include: determining the infiltration rate of the electrolyte according to at least two target volumes in the plurality of target volumes, and according to at least two time points corresponding to the at least two target volumes.

[0135] For example, a curve obtained based on the plurality of target volumes and the plurality of time points can be fitted, and a derivative is calculated, and a value obtained is the infiltration rate of the electrolyte.

[0136] For another example, a target volume at two adjacent time points can be divided by a time difference between the two adjacent time points, and a value obtained is the infiltration rate of the electrolyte at the time point. For example, a target volume at t1 is Va, and a target volume at t2 is Vb. The infiltration rate of the electrolyte at (t1-t2) / 2 is (Va-Vb) / (t1-t2).

[0137] The above technical solution determines a plurality of target volumes according to a plurality of reference volumes, reference pressures, and equilibrium pressures obtained at different times. The more values, the more accurate the target volumes obtained. Further, the infiltration rate of the electrolyte determined according to at least two target volumes in the plurality of target volumes is also more accurate and has higher precision.

[0138] After obtaining the infiltration rate of the electrolyte, the method 400 can further include: determining whether the electrolyte is sufficiently infiltrated into the pole piece of the electrode assembly according to the infiltration rate of the electrolyte.

[0139] Specifically, if it is determined according to the infiltration rate of the electrolyte that the electrolyte has sufficiently infiltrated the electrode sheet of the electrode assembly, the next operation can be performed. If it is determined according to the infiltration rate of the electrolyte that the electrolyte has not sufficiently infiltrated the electrode sheet of the electrode assembly, the battery can be left for a period of time to allow the electrolyte to continue to infiltrate the electrode sheet.

[0140] The technical solution can determine whether the electrolyte has sufficiently infiltrated the electrode sheet according to the infiltration rate of the electrolyte. On the one hand, the electrolyte can be allowed to sufficiently infiltrate the electrode sheet. On the other hand, the electrolyte can be prevented from infiltrating the electrode sheet for too long a time to extend the production cycle of the battery.

[0141] Further, the method 400 can further include adjusting the electrolyte according to the infiltration rate of the electrolyte.

[0142] If the infiltration rate of the electrolyte is slow, the production cycle of the battery can be affected, leading to an increase in the manufacturing cost of the battery. Therefore, in the case where the infiltration rate of the electrolyte is slow, the electrolyte can be adjusted by adjusting the type of organic solvent and / or additive of the electrolyte, or adjusting the proportion of electrolyte lithium salt, organic solvent, and additive, to optimize the performance of the electrolyte and improve the infiltration rate of the electrolyte.

[0143] Range anxiety is one of the key problems that limit the application of electric vehicles. The range of electric vehicles can be increased by improving the energy density of the battery. The energy density of the battery can be effectively improved by using a higher electrode sheet coating weight, a higher electrode sheet compaction density, and the like. However, these methods for improving the energy density of the battery can reduce the infiltration rate of the electrolyte to some extent. For example, as the electrode sheet compaction density increases, the porosity of the electrode sheet gradually decreases, and the pores between active materials are deformed due to the extrusion of the electrode sheet, leading to the difficulty of diffusion of the electrolyte in the electrode assembly, and thus the infiltration rate of the electrolyte becomes slow.

[0144] Therefore, the method 400 can further include adjusting the structure of the electrode assembly according to the infiltration rate of the electrolyte. Specifically, if the infiltration rate of the electrolyte is low, the coating weight or compaction density of the electrode sheet can be reduced, or the length and width of the electrode assembly can be adjusted.

[0145] The technical solution can adjust the structure of the electrode assembly according to the infiltration rate of the electrolyte, which can achieve the purpose of compatibility of the infiltration rate of the electrolyte and the energy density of the battery, and thus the performance of the battery can be effectively optimized.

[0146] The method embodiments of the embodiments of the present application are described in detail above, and the device embodiments of the embodiments of the present application are described below. The device embodiments correspond to the method embodiments, and thus the parts not described in detail can be referred to the method embodiments described above, and the device can implement any possible manner in the above method.

[0147] Figure 9 A schematic block diagram of a device 900 for measuring the electrolyte infiltration rate is shown. As shown, the device 900 can include: Figure 9

[0148] a measuring device 910 including a first cavity and a vent for inflating or deflating the first cavity, the first cavity having a reference volume;

[0149] a pressure sensor 920 connected to the first cavity for measuring a reference pressure of the first cavity after the gas fills the first cavity, and for measuring an equilibrium pressure between a second cavity and the first cavity after the first cavity communicates with the second cavity containing an electrode assembly and the gas pressure between the first cavity and the second cavity is balanced, the second cavity being infiltrated with the electrolyte;

[0150] wherein the reference volume, the reference pressure and the equilibrium pressure are used to determine a target volume, the target volume being used to determine the infiltration rate of the electrolyte, the target volume being the volume of the space in the second cavity other than the electrode assembly that is not infiltrated with the electrolyte.

[0151] Optionally, in an embodiment of the present application, a first switch is connected to the measuring device 910, and when the first switch is in an open state, the gas can enter or exit the first cavity through the vent.

[0152] When the first switch is switched from the open state to a closed state, the pressure measured by the pressure sensor 920 is the reference pressure.

[0153] Optionally, in an embodiment of the present application, the first cavity and the second cavity communicate through a connecting pipe, a second switch is provided on the connecting pipe, and the pressure sensor 920 is arranged between the second switch and the first cavity.

[0154] wherein when the second switch is in an open state, the pressure measured by the pressure sensor 920 is the equilibrium pressure.

[0155] Optionally, in an embodiment of the present application, the connecting pipe is a hard pipe.

[0156] ​Optionally, in an embodiment of the present application, a third switch is arranged on the second cavity, and when the third switch is in an open state, the second cavity is in communication with the atmosphere.

[0157] Optionally, in an embodiment of the present application, a liquid injection hole is further arranged on the second cavity, the electrolyte is injected into the second cavity through the liquid injection hole, and the third switch is connected with the liquid injection hole.

[0158] Optionally, in an embodiment of the present application, the pressure sensor 920 is an absolute pressure sensor.

[0159] Optionally, in an embodiment of the present application, the absolute pressure sensor is further configured to measure the electrode pressure in the second cavity.

[0160] The reference volume, the reference pressure, the equilibrium pressure and the electrode pressure are used to determine the target volume.

[0161] Optionally, in an embodiment of the present application, when the first cavity is in communication with the atmosphere, the pressure in the first cavity measured by the absolute pressure sensor is the electrode pressure.

[0162] Optionally, in an embodiment of the present application, the pressure sensor 920 is a relative pressure sensor.

[0163] Optionally, in an embodiment of the present application, the pressure sensor 920 is configured to measure the reference pressure and the equilibrium pressure multiple times at different time points to obtain multiple target volumes, at least two target volumes in the multiple target volumes and at least two time points corresponding to the at least two target volumes are used to determine the infiltration rate of the electrolyte.

[0164] Optionally, in an embodiment of the present application, the reference volume is a fixed value.

[0165] Optionally, in an embodiment of the present application, the shell for forming the second cavity is a rigid shell.

[0166] It should be understood that the device 900 can implement the corresponding operations in the method 400, and for the sake of brevity, the details are not repeated here. Accordingly, the device 900 can achieve the same technical effects as the aforementioned method 400, and for the sake of brevity of the content, the description is not repeated here.

[0167] While the present application has been described with reference to the preferred embodiments, it is to be understood that various other modifications can be made without departing from the scope of the present application. In particular, those skilled in the art will recognize that the technical features mentioned in the various embodiments can be combined in any way, as long as there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

[0168] While the present application has been described with reference to the preferred embodiments, it is to be understood that various other modifications can be made without departing from the scope of the present application. In particular, those skilled in the art will recognize that the technical features mentioned in the various embodiments can be combined in any way, as long as there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for measuring electrolyte infiltration rate, characterized in that: include: preparing a first cavity, and determining a reference volume and a reference pressure of the first cavity; preparing a second cavity; placing an electrode assembly in the second cavity and injecting an electrolyte so that the electrode assembly is immersed in the electrolyte; connecting the first cavity and the second cavity and determining an equilibrium pressure, wherein the equilibrium pressure is a pressure at which the air pressure between the second cavity and the first cavity is balanced; determining a target volume according to the reference volume, the reference pressure, and the equilibrium pressure, the target volume being the volume of the space in the second cavity excluding the electrode assembly that is not infiltrated by the electrolyte; The infiltration rate of the electrolyte is determined according to the target volume.

2. The method according to claim 1, characterized in that The first cavity is connected to a first switch, and determining the reference pressure of the first cavity includes: Turning on the first switch to inflate or deflat the first cavity; The first switch is closed and the pressure in the first cavity is measured to obtain the reference pressure.

3. The method according to claim 1 or 2, characterized in that The first cavity and the second cavity are connected via a connecting pipe, and a second switch is provided on the connecting pipe. The determining of the equilibrium pressure includes: Turn on the second switch; After the air pressure between the first cavity and the second cavity is balanced, the pressure is measured to obtain the balanced pressure.

4. The method according to claim 3, characterized in that The connecting pipe is a hard pipe.

5. The method according to claim 1 or 2, characterized in that A third switch is provided on the second cavity, and the method further includes: The third switch is turned on to allow the second cavity to communicate with the atmosphere.

6. The method according to claim 5, characterized in that The second cavity is further provided with a liquid injection hole, the electrolyte is injected into the second cavity through the liquid injection hole, and the third switch is connected to the liquid injection hole.

7. The method according to claim 5, characterized in that The reference pressure and the equilibrium pressure are obtained through a relative pressure sensor, and the relative pressure sensor is connected to the first cavity.

8. The method according to claim 7, characterized in that The determining of the target volume according to the reference volume, the reference pressure, and the equilibrium pressure includes: determining a plurality of target volumes at different times based on the reference volume, the reference pressure, and the equilibrium pressure; Determining the electrolyte infiltration rate according to the target volume includes: The infiltration rate of the electrolyte is determined according to at least two target volumes among the plurality of target volumes and according to at least two moments corresponding to the at least two target volumes.

9. The method according to claim 5, characterized in that The reference pressure and the equilibrium pressure are obtained through an absolute pressure sensor, and the absolute pressure sensor is connected to the first cavity.

10. The method according to claim 9, characterized in that The method further comprises: determining an electrode pressure within the second cavity; The determining of the target volume according to the reference volume, the reference pressure, and the equilibrium pressure includes: The target volume is determined according to the reference volume, the reference pressure, the equilibrium pressure, and the electrode pressure.

11. The method according to claim 10, characterized in that The determining the electrode pressure in the second cavity includes: connecting the first cavity to the atmosphere; The pressure in the first cavity is measured by the absolute pressure sensor, wherein the pressure measured by the absolute pressure sensor is the electrode pressure.

12. The method according to claim 1 or 2, characterized in that The reference volume is a fixed value.

13. The method according to claim 1 or 2, characterized in that The shell used to form the second cavity is a rigid shell.

14. A device for measuring electrolyte infiltration rate, characterized in that: include: A measuring device comprising a first cavity and a vent, wherein the vent is used to inflate or exhaust gas into the first cavity, and the volume of the first cavity is a reference volume; a pressure sensor connected to the first cavity, configured to measure a reference pressure of the first cavity after the first cavity is filled with gas, and to measure an equilibrium pressure between the second cavity and the first cavity after the first cavity is connected to a second cavity containing an electrode assembly and the gas pressure between the first cavity and the second cavity is balanced, wherein the second cavity is infiltrated with the electrolyte; The reference volume, the reference pressure and the equilibrium pressure are used to determine a target volume, and the target volume is used to determine the infiltration rate of the electrolyte. The target volume is the volume of the space in the second cavity other than the electrode assembly that is not infiltrated by the electrolyte.

15. The device according to claim 14, characterized in that The measuring device is connected to a first switch, and when the first switch is in an open state, the gas can enter or be discharged into the first cavity through the vent; When the first switch is switched from the open state to the closed state, the pressure measured by the pressure sensor becomes the reference pressure.

16. The device according to claim 14 or 15, characterized in that The first cavity and the second cavity are connected via a connecting pipe, and a second switch is provided on the connecting pipe; Wherein, when the second switch is in the open state, the pressure measured by the pressure sensor is the equilibrium pressure.

17. The device according to claim 16, characterized in that The connecting pipe is a hard pipe.

18. The device according to claim 14 or 15, characterized in that The second cavity is provided with a third switch. When the third switch is in an open state, the second cavity is communicated with the atmosphere.

19. The device according to claim 18, characterized in that The second cavity is further provided with a liquid injection hole, the electrolyte is injected into the second cavity through the liquid injection hole, and the third switch is connected to the liquid injection hole.

20. The device according to claim 18, characterized in that The pressure sensor is an absolute pressure sensor.

21. The device according to claim 20, characterized in that The absolute pressure sensor is also used to measure the electrode pressure in the second cavity; The reference volume, the reference pressure, the equilibrium pressure, and the electrode pressure are used to determine the target volume.

22. The device according to claim 21, characterized in that When the first cavity is connected to the atmosphere, the pressure in the first cavity measured by the absolute pressure sensor is the electrode pressure.

23. The device according to claim 18, characterized in that The pressure sensor is a relative pressure sensor.

24. The device according to claim 23, characterized in that The pressure sensor is used to measure the reference pressure and the equilibrium pressure multiple times at different moments to obtain multiple target volumes, and at least two target volumes among the multiple target volumes and at least two moments corresponding to the at least two target volumes are used to determine the infiltration rate of the electrolyte.

25. The device according to claim 14 or 15, characterized in that The reference volume is a fixed value.

26. The device according to claim 14 or 15, characterized in that The shell used to form the second cavity is a rigid shell.

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