Patent Application
20250167385
The present disclosure relates to a battery pack housing a battery including an exhaust valve.
A battery cell including an exhaust valve configured to open when an internal pressure is higher than a predetermined pressure enhances safety by opening the exhaust valve when the internal pressure abnormally increases. A battery pack housing the battery cell in an outer case thereof is required to safely exhaust an ejection substance exhausted from the exhaust valve to the outside of the outer case. In particular, in a battery cell using a non-aqueous electrolyte solution, since high-temperature gas obtained by vaporizing the electrolyte solution is ejected as the ejection substance from the exhaust valve, it is important to prevent an adverse effect caused by the ejection substance. In particular, it is important to prevent an adverse effect that a high-temperature ejection substance exhausted from the battery cell ignites outside the outer case. A battery pack has been developed in which a high-temperature ejection substance exhausted from an exhaust valve of a battery is exhausted to the outside of an outer case (PTL 1).
A battery pack according to an aspect of the disclosure includes: a battery block including a plurality of battery cells and a lead plate connecting the plurality of battery cells to one another, each of the plurality of battery cells including an exhaust valve; and a cover disposed on an outer periphery of the battery block, the cover including a gas exhaust port configured to exhaust an ejection substance from the exhaust valve to outside. In the battery block, the plurality of battery cells are parallel to one another, the plurality of battery cells have respective electrode end surfaces disposed in a same direction, and the lead plate is connected to the respective electrode end surfaces. The lead plate has a transmission gap configured to allow the ejection substance to transmit through the transmission gap. The cover includes an outer peripheral wall disposed at a periphery of the battery block, a closing plate closing an opening of the outer peripheral wall, and an exhaust duct disposed between the closing plate and the battery block, the exhaust duct being configured to exhaust the ejection substance. The exhaust duct is partitioned into a spreading duct and an outer peripheral duct by a partition rib. The partition rib demarcates the outer peripheral duct along an outer periphery of the spreading duct and has a communication opening therein configured to allow the ejection substance to flow from the spreading duct to the outer peripheral duct. The gas exhaust port is configured to exhaust the ejection substance from the exhaust valve of the each of the plurality of battery cells passing through the transmission gap of the lead plate, the spreading duct, and the outer peripheral duct, and is exhausted to outside from the gas exhaust port of the cover.
The battery pack described above provides an advantageous effect providing high safety by preventing an adverse effect such as ignition caused by the ejection substance at a high temperature exhausted from the battery cell being exhausted to the outside of the cover.
A battery pack according to an aspect of the disclosure includes: a battery block including a plurality of battery cells and a lead plate connecting the plurality of battery cells to one another, each of the plurality of battery cells including an exhaust valve; and a cover disposed on an outer periphery of the battery block, the cover including a gas exhaust port configured to exhaust an ejection substance from the exhaust valve to outside. In the battery block, the plurality of battery cells are parallel to one another, the plurality of battery cells have respective electrode end surfaces disposed in a same direction, and the lead plate is connected to the respective electrode end surfaces. The lead plate has a transmission gap configured to allow the ejection substance to transmit through the transmission gap. The cover includes an outer peripheral wall disposed at a periphery of the battery block, a closing plate closing an opening of the outer peripheral wall, and an exhaust duct disposed between the closing plate and the battery block, the exhaust duct being configured to exhaust the ejection substance. The exhaust duct is partitioned into a spreading duct and an outer peripheral duct by a partition rib. The partition rib demarcates the outer peripheral duct along an outer periphery of the spreading duct and has a communication opening therein configured to allow the ejection substance to flow from the spreading duct to the outer peripheral duct. The gas exhaust port is configured to exhaust the ejection substance from the exhaust valve of the each of the plurality of battery cells passing through the transmission gap of the lead plate, the spreading duct, and the outer peripheral duct, and is exhausted to outside from the gas exhaust port of the cover.
The battery pack described above prevents an adverse effect such as ignition caused by a high-temperature ejection substance being exhausted to the outside of the cover, and implements high safety. This is because, in the battery pack described above, energy of the ejection substance in the exhaust duct provided on an inner side of the cover is attenuated, and the ejection substance is exhausted to the outside. The exhaust duct efficiently attenuates the energy of the ejection substance by both the spreading duct and the outer peripheral duct, and exhausts the ejection substance to the outside. The spreading duct is a gap spreading planarly, and causes the ejection substance exhausted from the battery cell to spread planarly to attenuate energy. The ejection substance that has passed through the narrow transmission gap of the lead plate flows into the spreading duct, collides with an inner surface of the closing plate, spreads to the periphery, and spreads over a large planar area, so that the energy of the ejection substance is attenuated. The ejection substance flowing into the spreading duct radiates heat energy to the closing plate and the lead plate having a large area, and the heat energy is attenuated. The ejection substance with energy attenuated in the spreading duct flows into the outer peripheral duct, and the energy is further reduced and the ejection substance is exhausted from the gas exhaust port. The outer peripheral duct causes the ejection substance to flow into an elongated hollow path to radiate heat energy, and further reduces energy of motion by a flow resistance passing therethrough to exhaust the ejection substance from the gas exhaust port.
In the battery pack according to another aspect of the disclosure, one end of the outer peripheral duct may be defined as a first end, the other end of the outer peripheral duct may be defined as a second end. The first end of the outer peripheral duct may communicate with the gas exhaust port. The communication opening may be disposed between the second end of the outer peripheral duct and a center portion of the outer peripheral duct.
In the battery pack described above, since the outer peripheral duct is formed with a sealed chamber between the communication opening and the second end, the ejection substance passing through the communication opening collides with an inner surface of the outer peripheral wall which is an outer wall of the outer peripheral duct and is branched to both sides. A part of the branched ejection substance flows into the sealed chamber to reduce a flow rate on the exhaust side. Therefore, at the moment when the exhaust valve is opened, the energy of the high-temperature ejection substance exhausted by the high-speed flow is reduced by a buffering action of the sealed chamber. This configuration prevents leakage fire of the gas exhaust port caused by the exhausted ejection substance that flows at a high speed immediately after the exhaust valve is opened.
In the battery pack according to still another aspect of the disclosure, the battery block may further include a battery holder disposing the plurality of battery cells at fixed positions. The cover may further include: a holder outer peripheral wall molded unitarily with the battery holder; and a separation outer peripheral wall connected to the holder outer peripheral wall, the battery block being disposed inside the separation outer peripheral wall.
In the battery block described above, since a part of the cover is molded unitarily with the battery holder, a dedicated outer case for housing the battery block is not required, and the cover may have a simple structure. Further, since the separation outer peripheral wall is connected to the holder outer peripheral wall having a structure unitary with the battery holder to form the cover, a housing space for disposing built-in components such as a circuit board may be provided on an inner side of the separation outer peripheral wall.
In the battery pack according to still another aspect of the disclosure, the partition rib may be molded unitarily with the battery holder. In this configuration, the partition rib molded unitarily with the battery holder partitions the spreading duct and the outer peripheral duct while preventing leakage of the ejection substance. The ejection substance may flow from the spreading duct into the outer peripheral duct through the communication opening, and the energy of the ejection substance in the exhaust duct is reliably reduced.
In the battery pack according to still another aspect of the disclosure, the closing plate may have a fitting recess therein to which the partition rib is fitted and connected. The partition rib may be connected to the closing plate while being guided to the fitting recess. In this configuration, the partition rib and the closing plate are connected to each other without a gap therebetween, and leakage of the ejection substance of the spreading duct and the outer peripheral duct is effectively prevented. Therefore, the ejection substance of the spreading duct flows into the outer peripheral duct from the communication opening without leakage, and the energy of the ejection substance in the exhaust duct is reduced more reliably.
In the battery pack according to still another aspect of the disclosure, the closing plate may be molded unitarily with the partition rib. In this configuration, since the partition rib and the closing plate are connected to each other without a gap, the leakage of the ejection substance of the spreading duct and the outer peripheral duct is prevented, the ejection substance of the spreading duct flows into the outer peripheral duct through the communication opening without leakage, and the energy of the ejection substance in the exhaust duct is reduced more reliably.
In the battery pack according to still another aspect of the disclosure, the battery block may further include a battery holder disposing the plurality of battery cells at fixed positions. The partition rib may be a member separate from the battery holder and the closing plate, and is disposed between the battery holder and the closing plate.
In the battery pack according to still another aspect of the disclosure, the cover may have a rectangular outer shape, and includes a first outer peripheral wall, a second outer peripheral wall, a third outer peripheral wall, and a fourth outer peripheral wall. The outer peripheral duct may be disposed along inner sides of the first outer peripheral wall, the second outer peripheral wall, and the third outer peripheral wall. The gas exhaust port may be opened in the fourth outer peripheral wall.
In the battery pack described above, the ejection substance flows through the long outer peripheral duct disposed along the first to third outer peripheral walls, and the energy is reduced. Further, the ejection substance collides with the inner surface of the outer peripheral wall at both corner portion between the first and second outer peripheral walls and corner portion between the second and third outer peripheral walls, a direction of the ejection substance is changed, and the energy is further reduced. The ejection substance with the reduced energy is exhausted to the outside from the gas exhaust port of the fourth outer peripheral wall, and the adverse effect of the leakage fire is more effectively prevented.
In the battery pack according to still another aspect of the disclosure, the battery block may further include the battery holder disposing the plurality of battery cells at the fixed positions. The cover may further include: a holder outer peripheral wall molded unitarily with the battery holder; and a separation outer peripheral wall connected to the holder outer peripheral wall, the battery block being disposed inside the separation outer peripheral wall. The first outer peripheral wall, the second outer peripheral wall, and the third outer peripheral wall may constitute the holder outer peripheral wall, and the fourth outer peripheral wall may constitute the separation outer peripheral wall.
In the battery pack according to still another embodiment of the disclosure, a board housing space configured to house a circuit board therein may be provided between the separation outer peripheral wall and the battery block. A blocking rib may be disposed between the board housing space and the spreading duct, and the blocking rib may be configured to block the ejection substance. Both ends of the blocking rib may be connected to both ends of the partition rib.
In the battery pack described above, the ejection substance that passes through the lead plate and flows into the spreading duct may be prevented from directly flowing into the board housing space and may flow into the outer peripheral duct, and the energy is sufficiently reduced by the long outer peripheral duct provided along the first to third outer peripheral walls, thereby preventing the leakage fire from the outer peripheral duct.
In the battery pack according to still another aspect of the disclosure, the blocking rib may partition the board housing space and the spreading duct and communicates the outer peripheral duct with the board housing space.
In the battery pack described above, the ejection substance exhausted from the outer peripheral duct flows into the board housing space from the outer peripheral duct, and spreads therein to reduce the energy. The ejection substance with the reduced energy is effectively prevented from being exhausted from the gas exhaust port to the outside of the case and becoming leakage fire.
In the battery pack according to still another aspect of the disclosure, the blocking rib may be molded unitarily with the partition rib.
In the battery pack according to still another aspect of the disclosure, the fourth outer peripheral wall may have, at a corner portion, a collision wall for the ejection substance flowing out from a terminal end of the outer peripheral duct, and the gas exhaust port may be open at a center portion with respect to the collision wall.
In the battery pack described above, the ejection substance exhausted from the outer peripheral duct to the board housing space flows out from the outer peripheral duct, collides with the collision wall, is changed in direction, and spreads into the board housing space, so that energy is reduced, and the ejection substance is exhausted from the gas exhaust port.
In the battery pack according to still another aspect of the disclosure, the transmission gap of the lead plate may be 1 mm or less, and gap (d) of the spreading duct between the closing plate and the lead plate can be 3 mm or more.
In the battery pack according to still another aspect of the disclosure, inner width (W) of the outer peripheral duct between the outer peripheral wall and the partition rib may be 1 cm or less.
The disclosure will be detailed below with reference to the drawings. In the following description, terms indicating specific directions or positions (for example, “up”, “down”, and other terms including these terms) are used as necessary, and the use of these terms is to facilitate understanding of the invention with reference to the drawings. However, the technical scope of the invention is not limited by the meaning of these terms. In addition, portions denoted by the same reference numerals in a plurality of drawings indicate the same or equivalent portions or members.
Further, the following embodiments show specific examples of the technical idea of the invention, and the invention is not limited to the following. In addition, dimensions, materials, shapes, relative arrangements, and the like of components described below are intended to be shown without limiting the scope of the invention thereto unless otherwise specified. Contents described in one embodiment and examples can be applied to other embodiments and examples. Sizes, positional relationships, and the like of members shown in the drawings may be exaggerated for clarity of description.
Battery pack 100 shown in
Battery cell 1 is a cylindrical battery having electrode end surfaces 1A at both ends thereof. However, the battery in the battery pack of the disclosure is not limited to a cylindrical battery. As battery cell 1, a battery having another shape such as a chargeable rectangular battery can also be used. The cylindrical battery houses electrodes and an electrolyte solution in a cylindrical metal case. The metal case has a sealed structure in which a sealing plate is airtightly fixed to an opening portion of an outer can with a closed bottom. The outer can is manufactured by pressing a metal plate. The sealing plate is airtightly fixed to a peripheral edge of the opening portion of the outer can by crimping through a packing of an insulating material. In the rectangular battery, positive and negative electrode terminals insulated from each other are provided on the sealing plate that closes the opening portion of the metal case.
In battery cell 1, exhaust valve 1v is provided on the sealing plate in order to prevent an internal pressure of the metal case from becoming abnormally high and prevent the metal case from being damaged. Exhaust valve 1v has an ejection opening in the sealing plate. The ejection substance containing gas and the like inside exhaust valve 1v is exhausted through the ejection opening while exhaust valve 1v is opened. However, in the battery cell, the exhaust valve and the ejection opening thereof may be provided in the bottom of the outer can. When the internal pressure is higher than a predetermined pressure, for example, 1.5 MPa, exhaust valve 1v is opened to prevent the metal case from being damaged due to an increase in the internal pressure. Exhaust valve 1v is opened in an abnormal state. Accordingly, when exhaust valve 1v is opened, a temperature of battery cell 1 is also very high. Therefore, the ejection substance exhausted from opened exhaust valve 1v has an abnormally high temperature due to the mixture of gas and the electrolyte solution (ejection substance). In particular, in a non-aqueous electrolyte solution secondary battery such as a lithium ion battery as battery cell 1, the ejection substance may reach an abnormally high temperature of 400° C. or higher. Further, since the lithium ion battery is filled with a non-aqueous electrolyte solution, when the non-aqueous electrolyte solution is exhausted to the outside of the case at a high temperature, the non-aqueous electrolyte solution may contact air and ignite, and the temperature may become further abnormally high. Not only in the lithium ion battery, but also in other chargeable batteries, since the temperature of the ejection substance ejected from opened exhaust valve lv becomes high, it is important to attenuate the energy of the ejection substance and exhaust the ejection substance to the outside of the case to improve safety.
Battery block 10 disposes battery cells 1 at fixed position in battery holder 7 made of plastic. In battery block 10 shown in
In battery block 10 shown in
Battery holder 7 shown in
As shown in
Further, in battery holder 7, in addition to battery cells 1, lead plates 11 are also disposed at fixed positions by a fitting structure. Battery holder 7 has a fitting recess therein guiding lead plate 11, and lead plate 11 is fitted into the fitting recess, and is disposed at the fixed position. In addition, in the fitting of battery cell 1 and lead plate 11, lead plate 11 has a through hole therein. A positioning rib molded unitarily with battery holder 7 is inserted into the through hole, and lead plate 11 is disposed at the fixed position of battery holder 7. In battery holder 7, electrode end surfaces 1A at both ends of battery cells 1 are disposed along the same direction, and lead plates 11 are welded to electrodes provided on electrode end surfaces 1A. Lead plate 11 is connected to the electrode by a method such as laser welding, spot welding, or ultrasonic welding.
Cover 2 is made of a thermoplastic resin, such as polycarbonate, having high heat resistance properties, and is molded to have a rectangular shape. Battery block 10 and circuit board 13 are disposed inside cover 2. Cover 2 shown in the figures includes outer peripheral wall 3 having a rectangular outer shape and closing plate 4 that closes an opening portion of outer peripheral wall 3. Outer peripheral wall 3 includes holder outer peripheral wall 3X and separation outer peripheral wall 3Y. Holder outer peripheral wall 3X is molded unitarily with battery holder 7. Separation outer peripheral wall 3Y is connected to holder outer peripheral wall 3X. Circuit board 13 and battery block 10 are disposed on an inner side of separation outer peripheral wall 3Y. Outer peripheral wall 3 shown in
A gap is provided between cover 2 and battery block 10, i.e., between battery holder 7 and closing plate 4 shown in in
Exhaust duct 5 includes partition rib 6 provided between battery holder 7 and closing plate 4. Partition rib 6 partitions exhaust duct 5 into spreading duct 5A and outer peripheral duct 5B. Partition rib 6 is disposed along the outer periphery of spreading duct 5A. Outer peripheral duct 5B is disposed along the outer periphery of spreading duct 5A. Partition rib 6 has communication opening 16 therein. the ejection substance in spreading duct 5A is guided to outer peripheral duct 5B by communication opening 16. Partition rib 6 in
However, in the battery pack according to the disclosure, partition rib 6 is molded unitarily with closing plate 4, and partition rib 6 and closing plate 4 are connected to each other without a gap. Partition rib 6 is disposed at the fixed position without positional deviation while preventing leakage of the ejection substance. Further, partition rib 6 may be manufactured as a member separate from battery holder 7 and closing plate 4, and may be disposed at the fixed position between battery holder 7 and closing plate 4 by a fitting structure, bonding, or welding.
Spreading duct 5A which is a region surrounded by partition rib 6 is a gap extending along a planar shape, and configured to spread the ejection substance flowing in from transmission gap 12 of lead plate 11 along a planar shape to reduce the energy. The ejection substance that has transmitted narrow transmission gap 12 of lead plate 11 flows into spreading duct 5A collides with the inner surface of closing plate 4, spreads to the periphery, and spreads over a large planar area, thereby reducing the energy of the ejection substance. Since spreading duct 5A is disposed between closing plate 4 and lead plate 11, the ejection substance flowing into spreading duct 5A radiates heat energy to closing plate 4 and lead plate 11 having a large area to reduce the heat energy. Further, the temperature of the substance is also be lowered by causing spreading duct 5A to adiabatically expand the ejection substance that has transmitted narrow transmission gap 12. The decrease in temperature due to the adiabatic expansion is more effective by exhausting the ejection substance transmitted narrow transmission gap 12 to wide spreading duct 5A. Accordingly, transmission gap 12 is narrowed, for example, transmission gap 12 is 1 mm or less, and gap (d) of spreading duct 5A is, for example, three times or more transmission gap 12, so that the temperature of the ejection substance is effectively lowered and guided to gas exhaust port 15.
Elongated outer peripheral duct 5B disposed on the outer periphery of spreading duct 5A causes the ejection substance to flow into an elongated hollow path to radiate heat energy, and further attenuates energy of motion by a flow resistance passing through the path to exhaust the ejection substance from gas exhaust port 15. Since the energy of the ejection substance is reduced by the flow resistance in outer peripheral duct 5B, the energy of the ejection substance is efficiently reduced by setting inner width (W) between outer peripheral wall 3 and partition rib 6 to 1 cm or less.
In cover 2 shown in of
In outer peripheral duct 5B extending along first outer peripheral wall 3A to third outer peripheral wall 3C, one end of outer peripheral duct 5B as first end 5a communicates with gas exhaust port 15, and the other end of outer peripheral duct 5B as second end 5b is closed by closing rib 17 without communicating with gas exhaust port 15. Outer peripheral duct 5B has communication opening 16 provided therein between second end 5b and a center portion of outer peripheral duct 5B. Exhaust duct 5 shown in
In cover 2 shown in
Blocking rib 18 provides board housing space 8 between fourth outer peripheral wall 3D and battery block 10. Circuit board 13 is disposed in board housing space 8. Blocking rib 18 is disposed between board housing space 8 and spreading duct 5A, and prevents the ejection substance in spreading duct 5A from flowing into board housing space 8. Circuit board 13 is connected to battery cells 1 and has a battery protection circuit and the like mounted thereon. In cover 2 described above, board housing space 8 is partitioned from spreading duct 5A by blocking rib 18 to prevent the ejection substance in spreading duct 5A from directly flowing into board housing space 8. Gas exhaust port 15 communicates with board housing space 8. The ejection substance in outer peripheral duct 5B is guided from board housing space 8 to gas exhaust port 15 and is exhausted to the outside of cover 2. In this structure, the energy of the ejection substance flowing in from outer peripheral duct 5B is further reduced in board housing space 8, and the ejection substance is exhausted to the outside from gas exhaust port 15. The ejection substance flowing into board housing space 8 may thermally damage circuit board 13, but battery pack 100 in which the ejection substance is exhausted from exhaust valve 1v cannot be reused thereafter. Accordingly, in battery pack 100 in which circuit board 13 is thermally damaged and the temperature of the ejection substance exhausted from gas exhaust port 15 can be lowered, it is possible to effectively prevent the leakage fire and ensure higher safety.
Further, in cover 2 shown in
In cover 2 shown in
Circuit board 13 is connected to board holder 14 by a fitting structure and disposed at a fixed position. Board holder 14 is disposed on an upper surface of battery holder 7 shown in
The disclosure can be effectively used in a battery pack for safely exhausting an ejection substance from a battery cell to the outside.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-033540 | Mar 2022 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2023/000039 | 1/5/2023 | WO |
