Selective gas-permeable vent for a battery cell

Abstract

A battery cell comprises a housing with multiple walls defining a cell stack receiving area, and a one-way valve attached to the housing on one of the multiple walls and fluidically connected to the cell stack receiving area. The one-way valve includes an inlet attached to one of the multiple walls, an outlet, and a valve element that selectively connects the inlet and outlet to vent the cell stack receiving area. A gas-permeable membrane is positioned between the cell stack receiving area of ​​the housing and the outlet of the one-way valve. The gas-permeable membrane allows selected gases to flow from the cell stack receiving area through the outlet while preventing substances from entering the cell stack receiving area through the outlet.

Description

INTRODUCTION

[0001] The information provided in this section serves to present the general context of the disclosure. Works of the inventors mentioned herein, insofar as they are described in this section, as well as aspects of the description that may not have been prior art at the time of filing, are neither expressly nor implicitly recognized as prior art with respect to the present disclosure.

[0002] The present disclosure relates to the prior art in battery arrangements and in particular to a battery arrangement comprising a battery cell container with a selectively permeable vent.

[0003] Electric vehicles (EVs), such as battery electric vehicles (BEVs), hybrid vehicles, and / or fuel cell vehicles, comprise one or more electric motors and a battery system with one or more battery cells, modules, and / or packs. A power control system is used to manage the charging and / or discharging process of the battery system during charging and / or driving.

[0004] Battery cell casings, or "containers," comprise cathode electrodes, anode electrodes, and separators arranged in a battery cell stack. The cathode electrodes include a layer of active cathode material arranged on a cathode current collector. The anode electrodes include a layer of active anode material arranged on an anode current collector. The cathode and anode electrodes are connected by cathode and anode terminals located on an outer surface of the cell casing.

[0005] The battery modules are formed from several cell containers arranged within a housing. The anode and cathode terminals of the battery cells are connected to provide a desired output voltage. Each cell container includes a vent that opens when the pressure inside the container exceeds a certain value. SUMMARY

[0006] A battery cell according to the present disclosure comprises a housing with a plurality of walls defining a cell stack receiving area, a one-way valve attached to the housing on the plurality of walls and fluidically connected to the cell stack receiving area. The one-way valve comprises an inlet attached to one of the plurality of walls, an outlet, and a valve element that selectively connects the inlet and the outlet to vent the cell stack receiving area. A gas-permeable membrane is arranged between the cell stack receiving area of ​​the housing and the outlet of the one-way valve. The gas-permeable membrane allows selected gases to flow from the cell stack receiving area through the outlet while simultaneously preventing substances from entering the cell stack receiving area through the outlet.

[0007] In other features, the one-way valve comprises a valve seat and a check ball selectively arranged on the valve seat, with the gas-permeable diaphragm being located at the inlet of the one-way valve.

[0008] In other features, the one-way valve includes a flap that is pivotally mounted on one of the multiple walls that form the housing.

[0009] In other respects, the gas-permeable membrane includes a water-absorbing material.

[0010] In other cases, the gas-permeable membrane is formed from a gas-permeable material that encapsulates the water-absorbing material.

[0011] In other respects, the gas-permeable membrane is formed from a multitude of layers, including a first layer of a first gas-permeable material and a second layer of a water-absorbing material.

[0012] In other features, the multitude of layers includes a third layer made of a second gas-permeable material, with the second layer being formed from the water-absorbing material between the first layer and the third layer.

[0013] For other features, the first gas-permeable material is a first hydrophobic gas-permeable polymer and the second gas-permeable material is a second hydrophobic gas-permeable polymer.

[0014] In other respects, the water-absorbing material comprises a variety of ceramic particles.

[0015] For other characteristics, the multitude of ceramic particles defines a three-angstrom (3A) molecular sieve.

[0016] In other respects, the gas-permeable membrane is formed from a multitude of layers, including a first layer of a gas-permeable material and a second layer of a hydrophobic material.

[0017] In other respects, the second gas-permeable hydrophobic polymer that forms the second layer is a superhydrophobic gas-permeable polymer.

[0018] In other respects, the gas-permeable membrane includes a hydrophobic coating.

[0019] In other cases, the hydrophobic coating is formed from a superhydrophobic material.

[0020] In other features, the gas-permeable membrane includes a porous material that traps dirt.

[0021] In other respects, the gas-permeable membrane exhibits a gas permeability coefficient between approximately 280 and approximately 4100.

[0022] In other respects, the one-way valve includes a gas-permeable membrane element.

[0023] A method for venting a battery cell according to the present disclosure comprises providing an initial formation charge for a battery stack in a housing, venting gases generated by the battery stack during the initial formation charge through a gas-permeable membrane supported by the housing, providing a second formation charge for the battery stack in the housing, and venting gases generated by the battery stack during the second formation charge through the gas-permeable membrane supported by the housing.

[0024] For other features, the passage of gases through the gas-permeable membrane includes the passage of gases through a gas-permeable hydrophobic material.

[0025] Other features include the passage of gases through the gas-permeable membrane, as well as the passage of gases through a water-absorbing material.

[0026] Further applications of the present disclosure will become apparent from the detailed description, the claims, and the drawings. The detailed description and the specific examples serve only for illustration and are not intended to limit the scope of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present disclosure will be better understood from the detailed description and the accompanying drawings, whereby: Fig. 1 a front view of a prismatic cell container with a vent having a selectively permeable hydrophobic vent membrane according to one aspect of the present disclosure; Fig. 2 a front view of a prismatic cell container with a vent having a selectively permeable hydrophobic vent membrane according to a further aspect of the present disclosure; Fig. 3 a front view of a prismatic cell container with a vent having a selectively permeable hydrophobic vent membrane according to yet another aspect of the present disclosure; Fig. 4 shows a cross-sectional view of a selectively permeable hydrophobic venting membrane with encapsulated moisture-absorbing particles according to one aspect of the present disclosure; Fig. 5 shows a cross-sectional view of a selectively permeable hydrophobic venting membrane with a moisture-absorbing layer between a first and a second hydrophobic layer according to one aspect of the present disclosure; Fig. Figure 6 shows a cross-sectional view of a selectively permeable hydrophobic venting membrane with a superhydrophobic coating according to one aspect of the present disclosure; Fig. Figure 7 shows a cross-sectional view of a selectively permeable hydrophobic venting membrane with a particle trap layer according to one aspect of the present disclosure.

[0028] Reference symbols can be reused in the drawings to identify similar and / or identical elements. DETAILED DESCRIPTION

[0029] The size and shape of the housings can vary. Prismatic housings include a length spacing, a width spacing, and a height spacing and can be configured as tall or long housings. In a tall housing, the height spacing is greater than both the width and length spacing. In long housings, the length spacing is greater than both the height and width spacing. The terminals for tall cells are typically located on a top surface, while the terminals for long cells may be located on the top or end surfaces.

[0030] Prismatic container battery cells typically include a vent cap. During thermal runaway, the vent cap ruptures, allowing at least some of the venting gases and ejecta generated during thermal runaway to escape from the casing. Due to the tall cell design, the vent caps are usually located on the top or bottom. The top or bottom placement provides space for cooling systems that act on the side faces of the prismatic container battery cell.

[0031] In addition to venting gases produced during thermal runaway, battery casings are also vented during initial cell formation and charging. During charging, particularly the first, second, and / or subsequent charging cycles, the battery cells produce gas. At least during the first charge, the gas is released through a removable plug. During subsequent charging cycles, the gas slowly escapes from the cell. A gas-permeable vent would reduce the number of manufacturing steps, as it would allow venting during initial cell formation, and would also improve charging efficiency, since the gas could escape from the cell during charging cycles.

[0032] A battery cell according to the present disclosure is generally 10 in Fig. The battery cell 10 comprises a housing 12 formed from a plurality of walls 14. The plurality of walls 14 include a bottom wall 16, an upper wall 18, a first side wall 20, and a second side wall 22. The bottom wall 16, the upper wall 18, the first side wall 20, the second side wall 22, and additional walls (not shown) together form a battery stack receiving area 28. A battery stack 32 is arranged in the battery stack receiving area 28. The battery stack 32 is connected to a first terminal 34 and a second terminal 36, which are attached to the upper wall 18. The location of the first and second terminals can vary. Although the housing 12 is shown as a prismatic container, it can take on various shapes.

[0033] According to the present disclosure, the housing 12 includes a vent 40 that facilitates the passage of gases from the battery stack receiving area 28 into the surrounding environment. According to one exemplary aspect, the vent 40 includes a one-way valve 42 and a gas-permeable membrane 44. The gas-permeable membrane 44 is formed from a material selected to allow selected gases, such as carbon dioxide and selected alkanes / alkenes, to escape from the battery stack receiving area 28. The gas-permeable membrane 44 can be attached to the housing 12 by several techniques, including gluing, clamping between plates and gaskets, and crimping. Although the vent 40 is shown on the upper wall 18, it can also be arranged on any other of the plurality of walls 14, depending on the battery requirements.In a non-restrictive example, the gas-permeable membrane 44 has a gas permeability coefficient between approximately 280 and approximately 4100.

[0034] The one-way valve 42 comprises an inlet 46, which is fluidically connected to the battery stack receiving area 28, an outlet 48, and a valve element 50. The valve element 50 facilitates gas flow from the inlet 46 to the outlet 48 while simultaneously preventing flow in the reverse direction. The gas-permeable diaphragm 44 is located at the inlet 46 of the one-way valve 42. In this way, the one-way valve 42 allows gases to escape from the battery stack receiving area 28, which may be generated during the charging and / or discharging cycles of the battery cell 10.

[0035] According to a non-restrictive example, the one-way valve 42 can include a flap 52 which is pivotally attached to the housing 12 via a hinge 54. Gases flowing from the battery stack receiving area 28 into the inlet 46 exit through the outlet 48 and release the flap 52. The gases can then be released into the environment. In addition to facilitating the outgassing of gases from the battery stack receiving area 28, the gas-permeable membrane 44 prevents selected materials from entering the battery stack receiving area 28. The gas-permeable membrane 44 can, for example, be made of a gas-permeable, hydrophobic material 60 that allows selected gases to pass to the outside but prevents moisture from entering the battery stack receiving area 28.

[0036] The one-way valve 42 can take various forms. For example, the one-way valve 42 can have the form of a ball valve 62, as shown in Fig. Figure 2 shows that the ball valve 62 includes a check ball 63 which is biased against a valve seat 65 by a spring 68. The spring 68 is designed such that the check ball 63 can disengage from the valve seat 65 when subjected to a certain pressure. The selected pressure can be chosen to ensure positive flow through the one-way valve 42, thus minimizing backflow or exposure of the battery stack receiving area 28 to the environment.

[0037] The one-way valve 42 can also have the form of a double diaphragm valve 74, as in Fig. Figure 3 shows the double diaphragm valve 74 comprising a further gas-permeable diaphragm 80 arranged above the outlet 48. In this arrangement, gases generated in the battery stack receiving area 28 can first flow through the gas-permeable diaphragm 44 into a cavity 84 formed in the upper wall 18 between the inlet 46 and the outlet 48. Depending on the pressure of the gases in the cavity 84, the flow can proceed through another gas-permeable diaphragm 80 to the environment. If the pressure in the cavity 84 exceeds a selected pressure value, a further gas-permeable diaphragm 80 can be opened to allow the accumulating gases to escape to the environment.

[0038] The gas-permeable membrane 44 can take on various forms. For example, as in Fig. As shown in Figure 4, the gas-permeable hydrophobic material 60 can encapsulate a quantity of water-absorbing material 88 (e.g., desiccant). The water-absorbing material 88 can take the form of ceramic particles 90 forming a three-angstrom (3A) molecular sieve 92. Of course, other materials can also be used for water absorption. The water-absorbing material 88 not only absorbs any water that might enter the battery stack absorption area 28, but can also improve the structural stability of the gas-permeable membrane 44. The gas-permeable membrane 44 can alternatively be formed from a variety of layers 95, as shown in Figure 4. Fig. Figure 5 shows the multitude of layers 95 comprising a first layer 98, a second layer 100, and a third layer 102. The first layer 98 and the third layer 102 are formed from a gas-permeable, hydrophobic material, while the third layer 102 is formed from a water-absorbing material 88.

[0039] Fig. Figure 6 shows the gas-permeable membrane 44, which is formed from a plurality of layers 112, including a first layer 114 made of gas-permeable material 116 and a second layer 118 made of hydrophobic material 120. The second layer 118 can be a separate layer bonded to the first layer 114, or it can take the form of a hydrophobic coating made of hydrophobic or superhydrophobic material. It should be noted that the term "hydrophobic material" refers to a material that has a water contact angle of more than 90 degrees. Superhydrophobic material describes a material with a water contact angle of more than 150 degrees and a slip angle of 5 degrees.

[0040] The gas-permeable membrane 44 can also include a particle trapping layer 133, as shown in Fig.Figure 7 shows that the particle trap layer 133 is formed from a mesh of dirt-trapping material 135, which prevents foreign particles from entering the battery stack collection area 28 when the gas flows through the one-way valve 42. Thus, the vent 40 provides a passage for the gases generated by the battery stack 32 to flow out of the battery cell 10 to relieve the pressure in the battery stack collection area 28. Reducing the internal pressure in a battery cell can improve the performance and lifespan of the battery cells. The vent 40 not only allows gases to escape but also prevents the ingress of unwanted substances during a degassing cycle that could contaminate the internal components of the battery cell.

[0041] The vent 40 also provides advantages in the manufacture of battery cells. Previously, after manufacturing, a temporary plug was installed in a battery cell casing. The temporary plug was then removed during an initial formation charge of the battery cell, allowing the gases to escape. When the temporary plug is removed, the battery stack receiving area is exposed to the environment. After venting the gases generated during the initial formation, a permanent plug is installed and a sealing plate is welded in place before the battery cell undergoes a second formation charge. The vent described in accordance with the present disclosure eliminates the need for a temporary plug and the associated steps required to remove the plug and seal the battery cell casing after degassing.

[0042] According to the present disclosure, gases generated during the first formation can escape from the battery stack receiving area 28 through the gas-permeable membrane 44 and via the one-way valve 42. Gases from a second formation change can also flow directly from the battery stack receiving area 28 through the gas-permeable membrane 44 and via the one-way valve 42. By eliminating the need for a temporary plug, not only are battery manufacturing costs reduced, but battery cell efficiency is also increased by providing gas escape routes. Furthermore, the presence of the gas-permeable membrane 44 prevents the battery stack receiving area from being exposed to potential environmental contamination.

[0043] The foregoing description serves only for illustration and is not intended in any way to limit the disclosure, its application, or use. The comprehensive teachings of the disclosure can be implemented in a multitude of forms. Although this disclosure includes certain examples, the true scope of the disclosure should not be thereby limited, since other modifications will become apparent upon studying the drawings, the description, and the following claims. It is understood that one or more steps within a process may be carried out in a different order (or simultaneously) without altering the principles of the present disclosure.Although each of the embodiments described above has certain features, one or more of these features, described in relation to any embodiment of the disclosure, may be implemented in any other embodiment and / or combined with features of any other embodiment, even if this combination is not expressly described. In other words, the described embodiments are not mutually exclusive, and combinations of one or more embodiments remain within the scope of this disclosure.

[0044] When an element such as a layer, film, area, or substrate is described as lying "on" another element, it may lie directly on top of the other element, or there may be intermediate elements. Conversely, when an element is described as lying "directly on" another element, there are no intermediate elements.

[0045] The terms "approximately" and "essentially" are intended to encompass the degree of error associated with measuring a particular quantity based on the equipment available at the time the application was filed. For example, "approximately" and "essentially" may cover a range of ± 8% of a given value.

[0046] Spatial and functional relationships between elements (e.g., between modules, circuit elements, semiconductor layers, etc.) are described using various terms, including "connected," "interlocking," "coupled," "adjacent," "next to," "on top of," "above," "below," and "arranged." Unless a relationship between a first and a second element is explicitly described as "direct" in the above disclosure, this relationship may be a direct relationship, in which no other intervening elements exist between the first and the second element, or it may be an indirect relationship, in which one or more intervening elements (either spatial or functional) exist between the first and the second element.As used herein, the phrase “A, B and / or C” should be interpreted using a non-exclusive logical OR operation as logical (A OR-connected with B OR-connected with C) and not as “at least one of A, at least one of B and at least one of C”.

Claims

[1] Battery cell, comprising: a housing with a multitude of walls that form a cell stack receiving area; a one-way valve attached to the housing on one of the plurality of walls and fluidically connected to the cell stack receiving area, the one-way valve comprising an inlet attached to one of the plurality of walls, an outlet and a valve element that selectively connects the inlet and the outlet to vent the cell stack receiving area; and a gas-permeable membrane arranged between the cell stack receiving area of ​​the housing and the outlet of the one-way valve, wherein the gas-permeable membrane allows selected gases to flow from the cell stack receiving area through the outlet while preventing substances from entering the cell stack receiving area through the outlet. [2] Battery cell according to claim 1, wherein the one-way valve has a valve seat and a check ball selectively arranged on the valve seat and the gas-permeable membrane is arranged at the inlet of the one-way valve. [3] Battery cell according to claim 1, wherein the one-way valve comprises a flap pivotably attached to one of the plurality of walls forming the housing. [4] Battery cell according to claim 1, wherein the gas-permeable membrane comprises a water-absorbing material. [5] Battery cell according to claim 4, wherein the gas-permeable membrane is formed from a gas-permeable material that encapsulates the water-absorbing material. [6] Battery cell according to claim 4, wherein the gas-permeable membrane is formed from a plurality of layers, including a first layer formed from a first gas-permeable material and a second layer formed from a water-absorbing material. [7] Battery cell according to claim 1, wherein the gas-permeable membrane is formed from a plurality of layers, including a first layer of a gas-permeable material and a second layer of a hydrophobic material. [8] Battery cell according to claim 1, wherein the gas-permeable membrane has a hydrophobic coating. [9] Battery cell according to claim 1, wherein the gas-permeable membrane comprises a porous material that traps dirt. [10] Battery cell according to claim 1, wherein the gas-permeable membrane has a gas permeability coefficient between approximately 280 and approximately 4100.

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