US-12620640-B2 - Pouch cell vent pressure measurement apparatus

US12620640B2US 12620640 B2US12620640 B2US 12620640B2US-12620640-B2

Abstract

An apparatus for measuring a vent pressure of a pouch cell includes a pouch cell accommodating an electrode assembly therein, and formed with a heat fusion part on a side thereof; a measurement unit defining therein a space for seating the pouch cell, expanding the pouch cell by a negative pressure formed in the measuring unit, and measuring a vent pressure of the pouch cell; and a negative pressure forming unit connected to the measurement unit, and forming a negative pressure inside the measurement unit.

Inventors

Sang Mok Park
Dong Guk Park
Yong Ju Lim

Assignees

HYUNDAI MOTOR COMPANY
KIA CORPORATION

Dates

Publication Date: 20260505
Application Date: 20220725
Priority Date: 20210914

Claims (9)

1 . An apparatus for measuring a vent pressure of a pouch cell, comprising: the pouch cell, wherein the pouch cell is configured to accommodate an electrode assembly therein, and the pouch cell comprises a heat fusion part on a side thereof; a measurement chamber defining therein a space configured to seat the pouch cell, wherein the measurement chamber is configured to expand the pouch cell by a negative pressure produced in the measurement chamber, and to measure a vent pressure of the pouch cell; and a negative pressure forming device connected to the measurement chamber, and configured to produce the negative pressure inside the measurement chamber; and an outside air supply device connected to the measurement chamber at a lower end of the measurement chamber, wherein the outside air supply device is configured to form a hole in the pouch cell to supply outside air into the pouch cell and induce venting of the pouch cell when the pouch cell is not vented by the negative pressure inside the measurement chamber.
2 . The apparatus according to claim 1 , further comprising: a seating die disposed at a lower end of the measurement chamber, wherein the pouch cell is seated on the seating die; a contact panel disposed at an upper end in the measurement chamber, wherein the contact panel is configured to be moved up and down and to come into contact with the seated pouch cell; and a load sensor configured to measure a load generated by the pouch cell due to expansion of the pouch cell in response to a negative pressure inside the contact panel.
3 . The apparatus according to claim 2 , further comprising a pressure sensitive paper disposed between the pouch cell and the contact panel and configured to measure a contact area between the contact panel and the pouch cell.
4 . The apparatus according to claim 1 , wherein the negative pressure forming device comprises: a vacuum reservoir connected to the measurement chamber and configured to control the negative pressure formed in the measurement chamber; a vacuum pump configured to discharge air inside the measurement chamber and the vacuum reservoir; a first valve disposed between the vacuum reservoir and the vacuum pump; and a second valve disposed between the measurement chamber and the vacuum reservoir.
5 . The apparatus according to claim 1 , wherein the outside air supply device comprises: a compressor configured to compress outside air; an outside air reservoir connected to the compressor and configured to store the compressed outside air; an outside air passage configured to connect the compressor, the outside air reservoir, and the measurement chamber, and through which the compressed outside air of the outside air reservoir flows; and a third valve disposed between the measurement chamber and the outside air reservoir.
6 . The apparatus according to claim 5 , further comprising a seating die disposed at a lower end of the measurement chamber, wherein: the pouch cell is seated on the seating die; a groove is formed on a side of the seating die which is in contact with the pouch cell; the outside air passage is connected to the groove; and the outside air passage and the groove are configured to supply the outside air through the hole formed in the pouch cell.
7 . The apparatus according to claim 6 , wherein: the outside air passage has a branched configuration so that a first end of the outside air passage is connected to the groove and a second end of the outside air passage is connected to the inside of the measurement chamber; and the apparatus further comprises a fourth valve formed at the second end of the outside air passage and configured to form a negative pressure in the groove to cause a portion of the pouch cell to protrude into the groove.
8 . The apparatus according to claim 1 , further comprising a seating die disposed at a lower end of the measurement chamber, wherein: the pouch cell is seated on the seating die; a groove is formed on a side of the seating die which is in contact with the pouch cell; and a needle configured to form the hole in the pouch cell is disposed at a lower end of the groove.
9 . The apparatus according to claim 1 , wherein the measurement chamber comprises: a heater configured to create a high temperature environment inside of the measurement chamber; and a temperature sensor configured to measure a temperature inside of the measurement chamber.

Description

CROSS REFERENCE TO RELATED APPLICATION The present application claims under 35 U.S.C. § 119(a) the benefit of Korean Patent Application No. 10-2021-0122615 filed on Sep. 14, 2021, the entire contents of which are incorporated by reference herein for all purposes. BACKGROUND Technical Field The present disclosure relates to an apparatus for measuring a vent pressure of a pouch cell of a lithium secondary battery. More specifically, present disclosure relates to an apparatus configured to form a negative pressure environment around the pouch cell to induce venting of the pouch cell through a heat fusion part of the pouch cell, and to measure the pressure within the pouch cell upon venting. Description of the Related Art A lithium secondary battery is a battery which stores and produces electrical energy by the intercalation and deintercalation of lithium ions at a positive electrode and a negative electrode. The lithium secondary battery has excellent storage capacity, voltage, and lifespan characteristics when used in laptops, smartphones, and electric vehicles. The exterior, or casing, of a lithium secondary battery may configured as an angular, or prismatic type cell; a cylindrical type cell; or a pouch type cell. It is easy to change the external dimensions of the pouch type cell compared to the angular and cylindrical type cells, which typically are formed from aluminum or iron. In addition, since a pouch type cell is sealed by heat fusion, the pouch type cell is vented at a relatively low pressure when a swelling phenomenon occurs, thereby reducing risk of explosion. In addition, the pouch type cell has advantages in that it requires less space than angular and cylindrical type cells, and has a high energy density due to its light weight. In order to design a lithium secondary battery using a pouch type cell, or pouch cell, it is necessary to measure the vent pressure of the pouch cell. In the conventional art, air at high pressure is supplied to a specific part of the pouch cell to induce the venting of the pouch cell, and the vent pressure of the pouch cell is determined by measuring the air pressure immediately before venting occurs. However, this method may can be problematic because it can be difficult to accurately measure the vent pressure due to deformation of the pouch cell, resistance of the pouch cell to venting upon the application of pressurized air thereto, etc. The foregoing is intended to aid in the understanding of the background of the present disclosure, and is not intended to limit the present disclosure to the related art already known to those skilled in the art. SUMMARY The present disclosure has been made in an effort to solve the above problems associated with the related art, and the present disclosure provides an exemplary embodiment of an apparatus for measuring a vent pressure of a pouch cell, including a pouch cell accommodating an electrode assembly therein, and formed with a heat fusion part on a side thereof; a measurement unit defining therein a space for seating the pouch cell, expanding the pouch cell by a negative pressure formed in the measurement unit, and measuring a vent pressure of the pouch cell; and a negative pressure forming unit connected to the measurement unit, and forming a negative pressure inside the measurement unit. According to the above configuration, a method of venting the pouch cell while minimizing a change in the pressure of air inside the pouch cell and changing the pressure of air outside the pouch cell is provided. Thus, the vent pressure may be accurately measured as compared to the conventional method in which the pouch cell is vented by introducing air into the pouch cell. In an exemplary embodiment, an apparatus for measuring a vent pressure of a pouch cell according to the present disclosure includes the pouch cell. The pouch cell is configured to accommodate an electrode assembly therein, and the pouch cell includes a heat fusion part on a side thereof. The apparatus also includes a measurement unit defining therein a space configured to seat the pouch cell. The measurement unit is configured to expand the pouch cell by a negative pressure produced in the measurement unit, and to measure a vent pressure of the pouch cell. The apparatus further includes a negative pressure forming unit connected to the measurement unit, and configured to produce a negative pressure inside the measurement unit. In an exemplary embodiment, the apparatus further includes a seating die disposed at a lower end of the measurement unit, and the pouch cell is seated on the seating die. The apparatus also includes a contact panel disposed at an upper end in the measurement unit, and the contact panel is configured to be moved up and down and to come into contact with the seated pouch cell. The apparatus further includes a load sensor configured to measure a load generated by the pouch cell due to expansion of the pouch cell in response to a negative pressure in