Battery cell integrated exhaust diverter with particulate trap

Abstract

A vehicle battery unit exhaust system includes a battery pack that provides power to propulsion of a vehicle. The battery cell includes a battery can surrounding a component containing an electrolyte. The battery end cap captures the electrolyte portion. A mandrel having a longitudinal bore extends through the electrolyte and is disposed on the battery can central axis. The gas generated by the electrolyte may pass through the longitudinal aperture. A shaft is slidably disposed within the longitudinal bore with a proximal end of the shaft secured to a vent cap portion of the battery end cap. A circular score formed in the battery end cap releasably secures the vent cap portion to the battery end cap and is frangible, allowing the vent cap portion to be separated from the battery end cap and displacing with the shaft when the battery cell forms an overpressure condition.

Description

Technical Field

[0001] The present disclosure relates to electric vehicle batteries and battery venting. Background Art

[0002] For vehicle batteries, when the battery experiences heat propagation, hot gases and particles (ejecta) are expelled. To assist with battery thermal management, a vent cap can be used to allow and direct the ejection of gases and particles into the battery vent channel. Vent channel diverters have been developed in the battery vent channel to help direct hot gases and ejecta; however, these diverters can interfere with the operation of the vent cap.

[0003] Therefore, while current systems and methods for diverting battery gaseous vents achieve their intended purposes, a need remains for a new and improved system and method for venting gases and effluents from battery cells in a vehicle battery pack. Summary of the Invention

[0004] According to several aspects, a vehicle battery cell vent system includes a vehicle having a battery pack that provides power for propulsion and operation of the vehicle's systems. A battery cell of the battery pack includes an outer battery canister surrounding components of the battery cell, the components of the battery cell including an electrolyte disposed within the battery canister. A battery end cap captures a portion of the electrolyte. A mandrel having a tubular shape has a longitudinal bore extending through the mandrel, the mandrel extending through the electrolyte and disposed on a longitudinal center axis of the battery canister. The mandrel allows gas generated by the electrolyte to pass through the longitudinal bore. A shaft is slidably disposed within the longitudinal bore of the mandrel, with a proximal end of the shaft secured to a vent cap portion of the battery end cap. A circular notch is formed on the battery end cap to releasably secure the vent cap portion to the battery end cap. The circular notch is frangible, allowing the vent cap portion to separate from the battery end cap and allowing the vent cap portion to displace along with the shaft when an overpressure condition develops in the battery cell.

[0005] In another aspect of the present disclosure, the longitudinal bore includes a first bore having a first bore diameter A that opens into a second bore having a second bore diameter B, wherein the first bore diameter A is smaller than the second bore diameter B.

[0006] In another aspect of the present disclosure, the shaft includes a main shaft portion having a first shaft diameter C; and the first shaft diameter C is smaller than the first aperture A, thereby providing a sliding fit of the main shaft portion within the first aperture A.

[0007] In another aspect of the present disclosure, the shaft includes a stop block having a block diameter D greater than the first aperture A of the longitudinal bore, the stop block being slidably disposed within the second bore.

[0008] In another aspect of the present disclosure, the second hole terminates at a shoulder; and a stop block is slidably engaged within the second bore diameter B of the second hole, the stop block contacting the shoulder to terminate the sliding travel of the shaft in the shaft sliding direction.

[0009] In another aspect of the present disclosure, a particle trap is positioned on the vent cover portion, the particle trap providing a surface adhesive or treatment defining a generally circular end wall raised above the surface of the vent cover portion to collect and trap particles in the ejecta generated during battery cell venting. The particle trap defines one of a magnetic material that magnetically attracts and retains particles of the ejecta, or a chemical or adhesive material that captures particles that come into direct contact with the particle trap.

[0010] In another aspect of the invention, a wedge member is formed on the shaft; and a tapered outer surface of the wedge member contacts an inner tapered surface of a companion shape formed in the mandrel to arrest travel of the shaft.

[0011] In another aspect of the present disclosure, a plurality of wedge members extend inwardly from an inner wall of a mandrel, each including a tapered surface having a continuously downwardly decreasing diameter. The shaft has an upwardly directed tapered body that passes through the wedge members to prevent travel of the shaft against one of the wedge members when a pressure differential from an overpressure condition occurs.

[0012] In another aspect of the present disclosure, the vent cover portion includes a plurality of concentric brushes or porous material secured to an upper surface of the vent cover portion. The gaps or pores are designed to receive and capture at least one particle entrained in the ejecta arising during venting of the battery cell.

[0013] In another aspect of the present disclosure, the vent cover portion is thinner at the center of the vent cover than at the periphery of the vent cover, allowing the center of the vent cover to bend more easily when exposed to gas exhausted from the battery cells. The center of the vent cover forms a curved bowl shape during bending to improve the collection of ejecta particles exhausted from the battery cells. The vent cover portion is surface treated to attract the ejecta particles, the surface treatment defining at least one of a brush material and a porous material for attracting and capturing the ejecta particles, the brush material and the porous material defining a high-temperature resistant polymer.

[0014] According to several aspects, a method for forming a vehicle battery cell exhaust system includes: rolling a positive electrode and a negative electrode at a separator to form a winding; passing a hollow mandrel through the longitudinal center axis of the winding; engaging a bottom insulator at a first end of the winding proximate the negative electrode; connecting a top insulator to a second end of the winding opposite the negative electrode and proximate the positive electrode; slidably positioning the bottom insulator with the winding in a can; mounting a battery top assembly defining a collector above the positive terminal of the positive electrode and onto the top insulator; slidably inserting a shaft into a longitudinal hole of the mandrel positioned at a central position of the can, with a portion of the shaft extending beyond the bottom end of the mandrel; welding an end of the shaft to a surface of a vent cover portion of a battery end cover; and pushing the battery end cover with the shaft welded to the vent cover portion onto the first end of the can, and securing the battery end cover at the periphery of the first end of the can.

[0015] In another aspect of the present disclosure, the method further includes adding electrolyte to the header of the cell top assembly and crimping the cell top assembly containing the electrolyte at the second end of the can.

[0016] In another aspect of the present disclosure, the method further includes: extending a support ring of the cell end cap circumferentially outward from the vent cap portion to form a support surface to receive a portion of the electrolyte; and encapsulating the portion of the electrolyte using a raised shoulder around the support ring when the cell end cap is secured to the can.

[0017] In another aspect of the present disclosure, the method further includes extending a positive terminal outwardly from the positive electrode and extending a negative terminal outwardly from the negative electrode.

[0018] In another aspect of the present disclosure, the method further includes: forming a first aperture A in a longitudinal bore leading to a second bore having a second aperture B, wherein the first aperture A is smaller than the second aperture B; the second bore terminates at a shoulder; providing the shaft with a main shaft portion having a first shaft diameter C and a stop block having a stop block diameter D; forming the first shaft diameter C smaller than the first aperture A of the longitudinal bore, thereby providing a sliding fit of the main shaft portion within the first aperture A; positioning the stop block on the shaft, the stop block having a stop block diameter D larger than the first aperture A, so that the stop block is slidably fitted within the second aperture B of the longitudinal bore, and the stop block contacts the shoulder to terminate the sliding stroke of the shaft.

[0019] In another aspect of the present disclosure, the method further includes: circumferentially welding the bottom insulator to the first end of the winding; welding the bottom insulator to the can after the bottom insulator with the winding is disposed in the can; and welding the cell top assembly to the positive terminal of the positive electrode.

[0020] In another aspect of the present disclosure, the method further includes forming a circular score in the battery end cap that is frangible, allowing the vent cap portion to be separated from the battery end cap, and allowing the vent cap portion to be displaced with the shaft when an overpressure condition is established in the battery cell.

[0021] According to several aspects, a method for venting a vehicle battery cell includes: passing a hollow mandrel through the longitudinal center axis of a winding; installing the winding into a can; slidably inserting the shaft into a longitudinal hole of the mandrel positioned at a central position of the can, with a portion of the shaft extending beyond the bottom end of the mandrel; forming a frangible circular score in a battery end cover to distinguish a vent cover portion of the battery end cover; welding the portion of the shaft extending beyond the bottom end of the mandrel to a surface of the vent cover portion of the battery end cover; forming a battery cell by securing the battery end cover to one end of the can and introducing electrolyte into the can; when an overpressure condition is formed in the battery cell, rupturing the frangible circular score separating the vent cover portion from the battery end cover to allow the vent cover portion to be displaced from the can along with the shaft to vent gas from the battery cell.

[0022] In another aspect of the present disclosure, the method further includes: engaging a bottom insulator at a first end of the winding proximate the negative electrode; and coupling a top insulator at a second end of the winding opposite the negative electrode and proximate the positive electrode.

[0023] In another aspect of the present disclosure, the method further comprises: installing a cell top assembly defining a header over the positive terminal of the positive electrode and onto the top insulator; and pushing a cell end cap having a shaft welded thereto onto the first end of the can and securing the cell end cap to a periphery of the first end of the can.

[0024] Further areas of applicability will become apparent from the description provided herein.It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

[0026] Figure 1 is a left front perspective view of a vehicle having a vehicle battery unit vent system according to an exemplary aspect;

[0027] Figure 2 yes Figure 1 A partial elevational cross-sectional view of a battery cell of a battery cell exhaust system;

[0028] Figure 3 It is manufactured Figure 1 An illustration of the steps of a vehicle battery unit venting system;

[0029] Figure 4is a top perspective view of a vent cap portion of a battery end cap of the present disclosure in an initially assembled state, the vent cap portion having a circular score for joining the vent cap portion to the body of the battery end cap;

[0030] Figure 5 yes Figure 4 A top perspective view of the battery end cap after the circular score has been broken and the vent cap has been partially displaced;

[0031] Figure 6 is an elevational cross-sectional view of an improved battery cell of the present disclosure having a particulate trap;

[0032] Figure 7 is an elevational cross-sectional view of an improved battery cell of the present disclosure having a tapered vent cap stop member;

[0033] Figure 8 is an elevational cross-sectional view of an improved battery cell of the present disclosure having a raised edge vent cover portion with a particulate trap;

[0034] Figure 9 is an elevational cross-sectional view of an improved battery cell of the present disclosure having a plurality of tapered vent cap stop members;

[0035] Figure 10 is an elevational cross-sectional view of an improved battery cell of the present disclosure having a melted phase change material vent cap stop system;

[0036] Figure 11 is an elevational cross-sectional view of an improved battery cell of the present disclosure having a vent cap portion with a plurality of upwardly directed concentric rings to capture particles; and

[0037] Figure 12 is an elevational cross-sectional view of an improved battery cell of the present disclosure having a deformable vent cover portion. DETAILED DESCRIPTION

[0038] The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.

[0039] refer to Figure 1A vehicle battery cell venting system 10 is provided for a vehicle 12 having a battery pack 14 that provides power for propulsion and operation of various systems of the vehicle 12. The vehicle 12 may include a sedan, a sport utility vehicle, a van, a truck, or an autonomous vehicle, which collectively define a battery electric vehicle having a plurality of battery cells 16 of the battery pack 14. The vehicle 12 may also include an additional power source 17, including a gasoline engine or a hydrogen fuel cell, to provide a portion of the battery charging current or a portion of the propulsion force to assist the battery pack 14 in powering the vehicle 12. According to several aspects, the battery cells 16 may include any configuration of battery cell geometries, including cylindrical battery cells and / or rectangular battery cells, with the cylindrical battery cell geometry shown for illustration purposes only.

[0040] refer to Figure 2 And refer to it again Figure 1 , a single battery cell 16 defining a cylindrical battery cell includes an outer battery can 18 surrounding the components of the battery cell 16. An electrolyte 20 is disposed within the battery can 18, with a portion of the electrolyte 20 being captured using a battery end cap 22. The battery end cap 22 may be coupled to the battery can 18 using a weld joint 24 to isolate the battery cell 16 from the atmosphere. The mandrel 26 has a longitudinal bore 56 extending the entire length of the mandrel 26, reference Figure 3 As will be described in greater detail, a mandrel 26 extends through the electrolyte 20 and is disposed on a longitudinal center axis 28 of the battery can 18. The mandrel 26 allows gases generated by the electrolyte 20 during a heat propagation event in the battery cell 16 to pass through a longitudinal aperture 27 that causes an overpressure condition in the battery cell 16.

[0041] The shaft 30 is slidably disposed in the longitudinal hole 27 of the spindle 26. The shaft 30 includes a stopper 32 having a block diameter that is larger than the shaft diameter of the shaft 30. The block diameter of the stopper 32 and the shaft diameter of the shaft 30 are smaller than the longitudinal hole diameter of the spindle 26 to allow the shaft 30 to slide in the longitudinal hole 27 of the spindle 26, as shown in FIG. Figure 3 The proximal end of the shaft 30 is fixed to the vent cap portion 34 of the battery end cap 22, as shown in FIG. Figure 3 Described in more detail, the vent cover portion 34 of the battery end cover 22 is releasably secured to the battery end cover 22 via a circular score 36 formed in the battery end cover 22. The circular score 36 is frangible, allowing the vent cover portion 34 to be separated from the battery end cover 22 and to be displaced in an exemplary downward direction 38 along with the shaft 30 when an overpressure condition is established in the battery cell 16.

[0042] refer to Figure 3 And refer to it again Figure 1 and Figure 2, shows a series of exemplary manufacturing steps for forming the battery cell 16. Initially, the positive electrode 40 is positioned proximate to the negative electrode 42. A separator 44 is provided, and the positive electrode 40 and the negative electrode 42 are rolled or folded and thereby wound together with the separator 44 to form a winding 46. The winding 46 may include a positive terminal 47 extending outwardly from the positive electrode 40 and a negative terminal 48 extending outwardly from the negative electrode 42. The hollow mandrel 26 is then passed through the longitudinal center axis 28 of the winding 46, as shown in FIG. Figure 2 A bottom insulator 50 is then bonded to a first end of the winding 46 proximate to the negative electrode 42 . Similarly, a top insulator 52 is then bonded to a second end of the winding 46 opposite the negative electrode 42 and proximate to the positive electrode 40 .

[0043] The bottom insulator 50 is then circumferentially welded to the first end of the winding 46, and the bottom insulator 50 and the winding 46 are slidably positioned in the can 18. The bottom insulator 50 is further welded into the can 18. The cell top assembly 54 defining the header is mounted over the positive terminal 47 of the positive electrode 40 and mounted on the top insulator 52. The cell top assembly 54 is then welded to the positive terminal 47 of the positive electrode 40 extending outward from the second end of the can 18. Figure 2 The electrolyte 20 is added to the header of the cell top assembly 54 , and the cell top assembly 54 containing the electrolyte 20 is circumferentially crimped at the second end of the can 18 .

[0044] The shaft 30 is slidably inserted into a longitudinal bore 56 of the spindle 26, which is positioned at the center of the tank 18. The longitudinal bore 56 has a first bore diameter A and opens into a second bore 58 having a second bore diameter B. According to several aspects, the first bore diameter A is smaller than the second bore diameter B. The second bore 58 terminates at a shoulder 60. The shaft 30 includes a main shaft portion 62 having a first shaft diameter C, and the stop 32 has a stop diameter D. According to several aspects, the first shaft diameter C is smaller than the first bore diameter A of the longitudinal bore 56, thereby providing a sliding fit of the main shaft portion 62 within the first bore diameter A. According to several aspects, the stop diameter D is larger than the first bore diameter A, so that the stop 32 slidably fits only within the second bore diameter B of the longitudinal bore 56. The stop 32 contacts the shoulder 60 to terminate the sliding travel of the shaft 30 in the shaft sliding direction 64.

[0045] The portion 66 of the shaft 30 that extends beyond the bottom end 68 of the mandrel 26 is welded to a surface 70 of the vent cap portion 34 of the cell end cap 22. A support ring 72 of the cell end cap 22 extends circumferentially outward from the vent cap portion 34 and forms a support surface for receiving a portion of the electrolyte 20. When the cell end cap 22 is secured to the can 18, a portion of the electrolyte 20 is encapsulated around the raised shoulder 74 of the support ring 72. The cell end cap 22 with the shaft 30 welded thereto is then pushed onto the bottom or first end 76 of the can 18 and the reference Figure 2 The weld joint 24 is shown as being circumferentially welded at the perimeter of the first end 76 of the can 18 to complete the manufacture of the battery cell 16 .

[0046] refer to Figure 4 And refer to it again Figures 1 to 3 , the assembly 78 including the cell end cap 22, the mandrel 26, and the shaft 30 has the vent cap portion 34 releasably secured to the support ring 72 using the score 36. The score 36 provides a pressure-tight 360-degree seal of the vent cap portion 34 to the support ring 72 to seal the electrolyte 20 and the internal features of the cell 16 from the atmosphere under normal operating conditions of the cell 16. A weld joint 80 secures the shaft 30 to the surface 70 of the vent cap portion 34, as described above with reference to Figure 3 In the initial configuration condition of the assembly 78 , the stop block 32 is positioned above and out of contact with the shoulder 60 , so that if a subsequent high pressure condition, such as a battery heat propagation event, occurs during subsequent operation of the battery cell 16 , the vent cover portion 34 can be displaced from the support ring 72 .

[0047] refer to Figure 5 And refer to it again Figure 4 , under predetermined operating conditions of the battery cell 16, including during internal overpressure conditions of the battery cell caused by, for example, battery heat propagation, gas pressure within the battery cell 16 acting in the downward direction 64 causes a rupture of the frangible 360 ​​degree seal provided by the intact score 36. Thus, when the convex circumferential edge 82 of the vent cover portion 34 separates from the concave circumferential wall 84 of the support ring 72, the vent cover portion 34 is permitted to be displaced in the downward direction 64 from the support ring 72. When the vent cover portion 34 separates from the support ring 72, the vent path 86 opens to permit battery gases and ejecta to escape from the battery cell 16. When the stop block 32 is in direct contact with the shoulder 60, displacement of the vent cover portion 34 in the downward direction 64 is prevented, thereby maintaining the vent path 86 open without permitting the vent cover portion 34 to move and contact and potentially damage any portion of the battery pack 14. Thus, as Figure 3 As shown, the length of the portion 66 of the shaft 30 extending beyond the bottom end 68 of the spindle 26 is predetermined to provide a maximum opening for the exhaust path 86 while allowing the exhaust cover portion 34 to be retained by the stop block 32 .

[0048] refer to Figure 6 And refer to it again Figures 3 to 5According to another aspect, battery cell 87 is modified from battery cell 16 to further maximize the capture of ejecta escaping from battery cell 87. A particle trap 88 provides a surface adhesive or treatment that defines a generally circular end wall raised above a surface 90 of the modified vent cap portion 34' to collect and capture particles 92 in the ejecta that emerge during cell venting. The particle trap 88 may define a magnetic material to magnetically attract and retain particles 92 of the ejecta, or a chemical or adhesive material to capture particles 92 that come into direct contact with the particle trap 88. The particle trap 88 may be positioned and retained on the surface 90 of the modified vent cap portion 34' using a raised end wall 94 of the modified vent cap portion 34'. The raised end wall 94 allows an outer surface 96 of the modified vent cap portion 34' to be machined or modified to perform the function of the score 36 when the modified vent cap portion 34' is separated from the concave circumferential wall 84 of the support ring 72. The cell gases may then be allowed to fully exit the cell 16 via the flow paths 98, 98'. Figure 5 Similar to the discussion in reference Figure 3 As shown, the length of the portion 66 ′ of the shaft 30 extending beyond the bottom end 68 of the mandrel 26 is predetermined to provide a maximum opening for the flow paths 98 , 98 ′ while allowing the modified vent cap portion 34 ′ to be retained by the stop block 32 .

[0049] refer to Figure 7 And refer to it again Figures 3 to 6 , battery cell 99 is modified from battery cell 16 to improve the positioning of the vent cap during the escape of gases from battery cell 99. As an alternative to using a stop block 32, the shaft tip shape is designed to pass through the shape of the wedge-shaped channel when a pressure differential from a heat propagation jet occurs. The allowance for maintaining the improved vent cap portion 34" is provided by a wedge-shaped member 100 formed on the improved shaft 102. The tapered outer surface 104 of the wedge member 100 contacts the inner tapered surface 106 of the accompanying shape of the improved mandrel 108 to stop the travel of the improved shaft 102 in the downward direction 64 after the circular score 36 is broken. The other accessories and functions of the improved vent cap portion 34" are similar to the designs of the previous vent cap portions 34, 34' discussed above. The tapered geometry of the wedge member 100 provides further advantages over the stop block 32. In the event that the battery pack 14 is flipped over and turned upside down, the wedge geometry Ensure that the wedge member 100 is aligned with the cone The shaped surface 106 is frictionally engaged to hold the modified vent cover portion 34" in the open position. So that gas can be discharged even in the flipped state.

[0050] refer to Figure 8 And refer to it again Figure 6According to another aspect, battery cell 109 is modified from battery cell 16 to further maximize the capture of ejecta escaping from battery cell 109. To further maximize the capture of ejecta escaping from vented battery cell 16 and ejected from battery cell 16 if thermal propagation of battery cell 16 occurs, vent cover portion 110 is modified from vent cover portion 34, 34', 34" and provided with a particle trap 112 having a surface adhesive or treatment that defines a generally circular surface 114 raised above a surface 116 of vent cover portion 110 to collect and capture particles 118 escaping from ejecta ejected from battery cell 16 during cell venting. An additional end wall 120 is located on the periphery of vent cover portion 110 and includes a surface 122 raised above particle trap 112 to further capture particles 118.

[0051] refer to Figure 9 And refer to it again Figure 6 and Figure 8 According to another aspect, battery cell 123 is modified from battery cell 16 to improve the positioning of the vent cap during the escape of gas from battery cell 123. As an alternative to using a stop block 32, mandrel 124 includes a plurality of wedge-shaped members 126a, 126b, 126c, 126d, 126e, 126f extending inwardly from a mandrel inner wall 128. Each wedge-shaped member 126a, 126b, 126c, 126d, 126e, 126f includes a tapered surface 130 designed with a continuously decreasing diameter as it moves downward. Shaft 132 is modified from shaft 30 to include an upwardly directed tapered body 134 that passes through wedge-shaped members 126a, 126b, 126c, 126d, 126e, 126f when the pressure differential generated by the heat transfer jet pushes shaft 132 in the downward direction 64. When the conical surface 136 of the conical body 134 contacts a continuous wedge member among the wedge members 126a, 126b, 126c, 126d, 126e, 126f, multiple positions of the conical body 134, and thereby multiple positions of the shaft 132, are allowed to be used for different retaining positions of the improved vent cover portion 34'". The spindle 124 and the shaft 132 are both coaxially aligned on the longitudinal center axis 138 of the battery cell 123.

[0052] Continue to refer Figure 9, another function of the improved vent cover portion 34'" is similar to the previous vent cover portion 34, 34', 34" designs discussed above. The tapered geometry of the wedge members 126a, 126b, 126c, 126d, 126e, 126f and the tapered body 134 provides an additional advantage over the stop block 32. In the event that the battery cell 123 is flipped and inverted, the wedge geometry ensures frictional contact between one of the wedge members 126a, 126b, 126c, 126d, 126e, 126f and the tapered surface 136 of the tapered body 134 to maintain the improved vent cover portion 34" in the open position so that gas can be vented even in the flipped state.

[0053] refer to Figure 10 According to another aspect, a cell 140 is modified from cell 16 to improve the positioning of the vent cap during the escape of gas from cell 140. Mandrel 142 is hollow and centrally located within cell 140 having an inner wall 144. As an alternative to using shoulder 60, mandrel 142 includes a single wedge-shaped member 145 extending inwardly from mandrel inner wall 144 having an upwardly directed contact surface 146. Wedge-shaped member 145 also includes a tapered surface 148 having a continuously decreasing diameter upwardly oriented and oriented with respect to reference 146. Figure 9 The wedge members 126a, 126b, 126c, 126d, 126e, and 126f are depicted with the reverse geometry. The molten phase change material 150 is initially positioned within the bore of the mandrel 142 and below the stop surface 152 of the stop block 32. Unidirectional movement of the shaft 30 in the downward direction 64 begins when the molten phase change material 150 contacts the cell gases ejected during the heat propagation event of the molten phase change material 150. The shaft 30 and the vent cap portion 34 are displaced in the downward direction 64 until the stop surface 152 of the stop block 32 contacts the contact surface 146.

[0054] refer to Figure 11 According to another aspect, the battery cell 154 is modified from the battery cell 16 to improve positioning of the vent cover during escape of gases from the battery cell 154. The vent cover portion 34'" is modified to include a plurality of upwardly directed porous materials or wires 156 secured to an upper surface 158 of the vent cover portion 34'". Gaps 160 are provided between the consecutive concentric lines 156, the gaps 160 opening in an upward direction 162. The gaps 160 are sized to receive and capture at least one and, according to several aspects, a plurality of particles 164 entrained in ejecta emerging during venting of the battery cell 154. The gaps 160 may be less than or equal to approximately 100 μm.

[0055] refer to Figure 12According to another aspect, battery cell 166 is modified from battery cell 16 to provide an improved vent cap portion 168, such that vent cap portion 168 is thinner at vent cap center 170 than at vent cap periphery 172. This allows vent cap center 170 to flex more easily when exposed to gases exhausted from battery cell 166. During flexion, vent cap center 170 forms a curved bowl shape, which improves the collection of ejected particles 174. Vent cap portion 168 may also be provided with a surface treatment 176 to attract ejected particles 174. For example, surface treatment 176 may define a brush material or porous material for attracting and capturing particles 174. The brush material or porous material may be made of a flexible but high-temperature resistant polymer. A roughness-enhancing surface treatment 178 may also be provided to further aid in particle capture. The curved bowl shape and surface treatment 176 help retain particles 174, preventing them from being discharged into manifold 180, which receives gases exhausted from battery cell 166.

[0056] The disclosed vehicle battery cell vent system 10 offers several advantages. These include integrating a flow diverter into the battery cell. The vent is connected to a stopper via a mandrel. When the vent is opened, the vent cover rises to a predetermined height. The vent cover acts as both a flow diverter and a particle trap. Thus, the vehicle battery cell vent system 10 prevents thermal and mechanical damage to the battery modules and / or battery pack structure.

Claims

1. A vehicle battery unit exhaust system comprising: a vehicle having a battery pack that provides power for propulsion and operation of systems of the vehicle; a battery cell of the battery pack, the battery cell of the battery pack including an outer battery can surrounding components of the battery cell, the components of the battery cell including an electrolyte disposed within the battery can; a cell end cap, the cell end cap capturing a portion of the electrolyte; a mandrel having a longitudinal bore extending therethrough, the mandrel extending through the electrolyte and disposed on a longitudinal center axis of the battery can, the mandrel allowing gas generated by the electrolyte to pass through the longitudinal bore; as well as a shaft slidably disposed within the longitudinal bore of the mandrel, the proximal end of the shaft being secured to a vent cap portion of the battery end cap; as well as a circular score formed in the battery end cap and releasably securing the vent cover portion to the battery end cap, the circular score being frangible to allow the vent cover portion to be separated from the battery end cap and to allow the vent cover portion to be displaced with the shaft when an overpressure condition is established in the battery cell.

2. The vehicle battery unit venting system according to claim 1, wherein: The longitudinal hole includes a first hole having a first aperture A, the first hole leading to a second hole having a second aperture B, wherein the first aperture A is smaller than the second aperture B.

3. The vehicle battery unit venting system of claim 2, wherein: The shaft includes a main shaft portion having a first shaft diameter C; and The first shaft diameter C is smaller than the first aperture A, thereby providing a sliding fit of the main shaft portion within the first aperture A.

4. The vehicle battery unit exhaust system according to claim 3, wherein: The shaft includes a stop block having a block diameter D larger than the first aperture A of the longitudinal hole, wherein the stop block is slidably disposed in the second hole.

5. The vehicle battery unit venting system of claim 4, wherein: the second hole terminating at a shoulder; and The stop block is slidably fitted within the second bore diameter B of the second hole, wherein the stop block contacts the shoulder to terminate the sliding travel of the shaft in the shaft sliding direction.

6. The vehicle battery cell venting system according to claim 1 further includes a particle trap positioned on the vent cover portion, the particle trap providing surface viscosity or treatment, the surface viscosity or treatment defining a generally circular end wall raised above the surface of the vent cover portion to collect and capture particles of ejecta arising during battery cell venting, the particle trap defining one of a magnetic material or a chemical or viscous material, the magnetic material magnetically attracting and retaining particles of the ejecta, the chemical or viscous material to capture particles of the ejecta that come into direct contact with the particle trap.

7. The vehicle battery unit vent system of claim 1 , further comprising: a wedge-shaped member formed on the shaft; as well as The tapered outer surface of the wedge member contacts the inner tapered surface of the accompanying shape formed on the spindle to prevent the travel of the shaft.

8. The vehicle battery unit vent system of claim 1 , further comprising: a plurality of wedge-shaped members extending inwardly from an inner wall of the mandrel and each comprising a tapered surface having a shape in which the diameter decreases continuously downward; as well as A shaft having an upwardly directed tapered body passes through the wedge members to arrest travel of the shaft against one of the wedge members when a pressure differential from the overpressure condition occurs.

9. The vehicle battery unit venting system of claim 1 , wherein: The exhaust cover portion includes a plurality of wires fixed to an upper surface of the exhaust cover portion; as well as An upwardly open gap is provided between the consecutive conductive lines, the gap receiving and capturing at least one particle entrained in the ejecta arising during venting of the battery cell.

10. The vehicle battery unit vent system of claim 1, wherein: The vent cover portion is thinner at the center of the vent cover than at the periphery of the vent cover, so that the vent cover center is more likely to bend when in contact with gas exhausted from the battery cell, wherein the vent cover center forms a curved bowl shape during bending to improve the collection of ejecta particles exhausted from the battery cell; and The exhaust cover portion is surface treated to attract the ejecta particles, wherein the surface treatment defines at least one of a brush material and a porous material for attracting and capturing the ejecta particles, the brush material and the porous material defining a high temperature resistant polymer.

Images