Gas flow rate measuring device for secondary battery and measuring method using the same

Abstract

A gas flow measurement device for a secondary battery according to one embodiment of the present invention includes a chamber that accommodates a secondary battery, and a pipe-shaped flow measurement unit that is connected to an outlet of the chamber.

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0144750, dated November 2, 2022, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a safety measurement device for a secondary battery, and more particularly to a device and method for measuring the safety of a single secondary battery by measuring the flow rate of gas generated in the event of ignition. [Background technology]

[0003] In modern society, as the use of portable devices such as mobile phones, laptops, video cameras, and digital cameras has become commonplace, active development of technologies related to these mobile devices is taking place. Furthermore, rechargeable secondary batteries are being used as power sources for electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (P-HEVs), etc., as a solution to problems such as air pollution caused by existing gasoline-powered vehicles that use fossil fuels, and so there is an increasing need for development of secondary batteries.

[0004] Currently commercially available secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium secondary batteries. Among these, lithium secondary batteries are attracting attention due to their advantages of being free to charge and discharge, having a very low self-discharge rate, and having a high energy density, as they have almost no memory effect compared to nickel-based secondary batteries.

[0005] Such lithium secondary batteries mainly use lithium-based oxides and carbon materials as the positive and negative electrode active materials, respectively, and include an electrode assembly in which a positive electrode plate and a negative electrode plate, each coated with the positive and negative electrode active materials, are arranged with a separator sandwiched therebetween, and a battery case that hermetically houses the electrode assembly together with an electrolyte.

[0006] Generally, lithium secondary batteries can be classified into can-type secondary batteries, in which an electrode assembly is housed in a metal can, and pouch-type secondary batteries, in which an electrode assembly is housed in a pouch made of an aluminum laminate sheet, depending on the shape of the exterior material.

[0007] While secondary batteries used in small devices typically have two to three battery cells, secondary batteries used in medium- to large-sized devices such as automobiles typically use battery modules in which multiple battery cells are electrically connected. These battery modules improve capacity and output by connecting multiple battery cells in series or parallel to form a stack of battery cells. One or more battery modules can be attached to various control and protection systems, such as a Battery Disconnect Unit (BDU), Battery Management System (BMS), and cooling system, to form a battery pack.

[0008] In particular, with the recent development of high-capacity cells, the safety of secondary batteries, especially their thermal propagation characteristics, is recognized as important. Such safety characteristics can be achieved by simulating overcharge or overheating conditions in secondary batteries and analyzing the gases generated when they ignite. However, when analyzing multiple secondary batteries at once, it is difficult to compare the characteristics of each secondary battery and it is also difficult to perform accurate analysis. Therefore, there is a need for an apparatus and method that can accurately analyze the gases generated when a single secondary battery (single cell) is overcharged or overheated. Summary of the Invention [Problem to be solved by the invention]

[0009] The problem to be solved by the present invention is to provide an apparatus and method that can accurately analyze gas generated during overcharge and overheating with a simple structure so that the heat transfer characteristics of a single secondary battery can be evaluated.

[0010] However, the problems to be solved by the embodiments of the present invention are not limited to the above problems, and can be variously expanded within the scope of the technical ideas included in the present invention. [Means for solving the problem]

[0011] A gas flow measurement device for a secondary battery according to an embodiment of the present invention may include a chamber that accommodates a secondary battery, and a pipe-shaped flow measurement unit that is connected to an outlet of the chamber.

[0012] The length of the flow rate measuring portion may be between 800 mm and 2,000 mm.

[0013] The diameter of the flow measuring portion may be between 2.5 cm and 13 cm.

[0014] After the secondary battery is received, the volume of the remaining space in the chamber may be 0.1L to 5L.

[0015] The chamber may have a box-shaped rectangular parallelepiped shape.

[0016] The chamber and the flow rate measuring unit may be made of aluminum or stainless steel.

[0017] A method for measuring a gas flow rate of a secondary battery according to another embodiment of the present invention includes the steps of accommodating a secondary battery in a chamber, increasing the temperature inside the chamber to induce ignition in the secondary battery, and measuring the temperature of gas generated from the secondary battery due to the ignition, and the gas may be discharged to a pipe-shaped flow rate measuring unit connected to an outlet of the chamber.

[0018] The gas discharged from the flow rate measuring unit may include only the gas generated from the secondary battery without mixing with a separate carrier gas.

[0019] 95% or more of the gas generated from the secondary battery may be discharged to the flow rate measuring unit.

[0020] The chamber may accommodate one to four of the secondary batteries. [Effects of the Invention]

[0021] According to an embodiment of the present invention, it is possible to provide an apparatus and method that can accurately analyze gas generated during overcharge and overheating with a simple structure so as to evaluate the heat transfer characteristics of a single secondary battery.

[0022] The effects of the present invention are not limited to those mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is a diagram showing a gas flow rate measuring device for a secondary battery according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0024] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention may be embodied in various different forms and is not limited to the embodiments set forth herein.

[0025] In order to clearly explain the present invention, parts that are not necessary for the explanation will be omitted, and the same reference numerals will be used throughout the specification to refer to the same or similar components.

[0026] In addition, the size and thickness of each component shown in the drawings are arbitrarily shown for the convenience of explanation, and the present invention is not necessarily limited to those shown in the drawings. In the drawings, thicknesses are exaggerated to clearly show various layers and regions. In the drawings, thicknesses of some layers and regions are exaggerated for the convenience of explanation.

[0027] Furthermore, when an element such as a layer, film, region, or plate is said to be "on" another element, this includes not only the case where it is "directly on" the other element, but also the case where there is another element between them. Conversely, when an element is said to be "directly on" another element, it means that there is no other element between them. Furthermore, being "on" a reference element means being located above or below the reference element, and does not necessarily mean being located "on" in the opposite direction of gravity.

[0028] Also, throughout the specification, when a part is said to "comprise" a certain element, this does not mean that it excludes other elements and may further include other elements, unless specifically stated to the contrary.

[0029] Also, throughout the specification, "in a plane" means a view of the subject part from above, and "in cross section" means a view of the subject part cut vertically from the side.

[0030] The gas analyzer for a secondary battery will be described below with reference to FIG.

[0031] FIG. 1 is a diagram showing a gas flow rate measuring device for a secondary battery according to one embodiment of the present invention.

[0032] The gas analyzer 100 for a secondary battery is configured to analyze gas emitted from a secondary battery 200.

[0033] The gas analyzer 100 for a secondary battery includes a chamber 110 that houses the secondary battery 200 and a flow rate measuring unit 120 that has a pipe shape to serve as a passage for gas discharged from the secondary battery 200. Although not shown, the analyzer may further include an overload means (not shown) that is attached to the inside or outside of the chamber 110 and raises the internal temperature, and a flow meter (not shown) that is attached to the inside or outside of the flow rate measuring unit 120 and measures the flow rate.

[0034] The chamber 110 is configured to accommodate the secondary battery 200, which is the object to be analyzed. For example, the chamber 110 may have a rectangular box shape with an internal space, as shown in Fig. 1. The chamber 110 may be made of aluminum or stainless steel to withstand heat, etc.

[0035] The size of the space inside the chamber 110 may be set so that only one secondary battery 200 can be accommodated therein. In this case, the size of the internal space is set so that the volume of the remaining portion after one secondary battery 200 is accommodated is 0.1 L to 5 L. If the volume exceeds 5 L and is excessively large compared to the size of the secondary battery 200, some of the high-temperature gas may change phase to liquid as it passes through the space. As a result, the amount of high-temperature gas measured by the flow rate measuring unit 120 may be less than the actual flow rate of the generated high-temperature gas. Therefore, accurate measurement becomes difficult, so it is necessary to limit the remaining volume after accommodating the secondary battery 200 to the above range.

[0036] Also, only one secondary battery 200 can be accommodated in the chamber 110, and its characteristics can be evaluated. Conventionally, heat propagation characteristics have been simulated and measured in a stack or module state in which multiple secondary batteries 200 are stacked, but this has the problem of making it difficult to ensure safety at the experimental stage because the scale of ignition increases and the amount of gas generated is large. Therefore, in an embodiment of the present invention, one to four secondary batteries 200 are accommodated in the chamber 110, and the gas flow rate is measured when ignition occurs.

[0037] An outlet 111 through which high-temperature gas generated from the secondary battery 200 is discharged is formed on one side of the chamber 110, and a pipe-shaped flow rate measuring unit 120 is connected to the outlet 111. The flow rate measuring unit 120 is formed in a pipe shape so that the high-temperature gas generated from the secondary battery 200 can pass through.

[0038] A flow meter capable of measuring the flow rate of gas passing through the flow measuring unit 120 may be provided inside or outside the flow measuring unit 120. The flow measuring unit 120 may also be made of a material that can withstand heat and pressure, such as aluminum or stainless steel. The flow measuring unit 120 may be located in the center of one side of the box-shaped chamber 110, or may be formed on only one side as shown in FIG. 1, or may be formed on both sides. However, in this case, the flow measuring unit 120 is configured only for discharging gas, and in this embodiment of the present invention, the flow rate is measured without introducing a separate carrier gas for flow rate measurement.

[0039] The length L of the flow measuring unit 120 may be 800 mm to 2,000 mm, and the diameter D may be 2.5 cm to 13 cm. Within these ranges, the length L and diameter D of the flow measuring unit 120 can be appropriately adjusted depending on the size of the chamber 110. That is, the smaller the chamber 110, the smaller the length L and diameter D may be. Furthermore, when the length L of the flow measuring unit 120 is 800 mm to 2,000 mm and the diameter D is 2.5 cm to 13 cm, the gas generated in the secondary battery 200 can pass through the flow measuring unit 120 while maintaining its initial temperature, thereby enabling accurate measurement of the flow rate of the generated gas. That is, when the length of the flow measuring unit 120 is long and the diameter is small, a flow loss occurs during the process of passing through the flow measuring unit 120, resulting in a problem of the actual flow rate being measured lower than expected. Therefore, for accurate flow rate measurement, it is preferable to control the length L and diameter D of the flow measuring unit 120 within the above ranges.

[0040] According to the gas flow measurement device of the embodiment of the present invention as described above, it is possible to accurately measure the flow rate of the gas discharged from one secondary battery 200 without any loss in the flow rate of the generated gas.

[0041] Next, a gas flow rate measuring method for a secondary battery according to another embodiment of the present invention will be described with reference to FIG.

[0042] First, one secondary battery 200 is placed inside the chamber 110. At this time, the flow rate is measured for only one secondary battery 200, not for multiple secondary batteries, improving safety and enabling evaluation of each battery cell. Furthermore, compared to performing a simulation experiment on multiple secondary batteries 200 at once, the time and energy required for heating to cause ignition can be reduced.

[0043] Next, the internal temperature is increased by an overload means (not shown) attached inside or outside the chamber 110. In the embodiment of the present invention, only heating by the overload means is described as an example, but the present invention is not limited thereto, and an overload can also be induced in the secondary battery 200 by inducing an overcharged state, etc. When an overload is induced in the secondary battery 200 by heating, etc., the secondary battery 200 emits high-temperature gas.

[0044] When high-temperature gas is released, all of the high-temperature gas passes through the outlet 111 and passes through the flow rate measuring unit 120. The flow rate and temperature of the high-temperature gas passing through the flow rate measuring unit 120 are measured using a flow meter. Since the flow rate of the high-temperature gas released from the secondary battery 200 is measured by passing all of the generated gas through the flow rate measuring unit 120 without introducing a separate reference gas (carrier gas) to measure the flow rate, the flow rate can be measured accurately and simply without loss of the generated gas. In other words, introducing a carrier gas not only complicates the process but also can reduce the actual measured flow rate by partially liquefying the high-temperature gas as it mixes with other gases. As described above, in embodiments of the present invention, the volume of the remaining space within the chamber 110 excluding the secondary battery 200 is limited to 0.1 L to 5 L, and the length L and diameter D of the flow rate measuring unit 120 are limited to 800 mm to 2000 mm and 2.5 cm to 13 cm, respectively, thereby preventing the high-temperature gas from liquefying while passing through the remaining space or the flow rate measuring unit.

[0045] Next, the characteristics of the generated gas are analyzed with reference to the flow rate or temperature measured by the flow rate measurement unit 120. For example, it is possible to predict whether or not the heat transfer characteristics will be improved based on the level of a specific flow rate.

[0046] As described above, according to the method for measuring the gas flow rate of a secondary battery according to the embodiment of the present invention, the flow rate of the generated high-temperature gas can be accurately measured without loss using a simple structure and method.

[0047] Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited to these, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the claims also fall within the scope of the present invention. [Explanation of symbols]

[0048] 100: Gas flow measuring device 200: Secondary battery 110: Chamber 111: Exhaust port 120: Flow measurement unit

Claims

1. a chamber for housing the secondary battery; and A gas flow rate measuring device for a secondary battery, comprising a flow rate measuring unit having a pipe shape connected to the outlet of the chamber.

2. 2. The gas flow measurement device for a secondary battery according to claim 1, wherein the length of the flow measurement portion is 800 mm to 2,000 mm.

3. The diameter of the flow measuring portion is 2.5 cm to 13 cm. The gas flow rate measuring device for a secondary battery according to claim 1 or 2.

4. After the secondary battery is received, the volume of the remaining space in the chamber is 0.1 L to 5 L. The gas flow rate measuring device for a secondary battery according to claim 3 .

5. The chamber has a box-shaped rectangular parallelepiped shape. The gas flow rate measuring device for a secondary battery according to claim 1 .

6. The gas flow rate measuring device for a secondary battery according to claim 1 , wherein the chamber and the flow rate measuring unit are made of aluminum or stainless steel.

7. placing a secondary battery in the chamber; increasing the temperature inside the chamber to induce ignition in the secondary battery; and measuring the temperature of gas generated from the secondary battery due to the ignition; The gas is discharged to a flow rate measuring section having a pipe shape connected to an outlet of the chamber.

8. The method of claim 7 , wherein the gas discharged from the flow rate measuring unit includes only the gas generated from the secondary battery without mixing with a separate carrier gas.

9. The method for measuring a gas flow rate of a secondary battery according to claim 7 , wherein 95% or more of the gas generated from the secondary battery is discharged to the flow rate measuring section.

10. One to four of the secondary batteries are housed in the chamber. The method for measuring a gas flow rate of a secondary battery according to claim 7.

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