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DE-102024132650-A1 - Battery cell with the possibility of forming a gas channel in case of thermal runaway.

DE102024132650A1DE 102024132650 A1DE102024132650 A1DE 102024132650A1DE-102024132650-A1

Abstract

Battery cell (1), comprising - a housing (2), with a housing wall (3) - a safety pressure valve (4) or housing weak point arranged in the housing wall (3), - an active material (5) arranged inside the housing (2), - at least one solid body (7, 8) arranged in a space (6) between the housing wall and the active material (5), which only partially covers the housing wall (3), wherein the solid body (7, 8) expands or deforms when a limit temperature is exceeded, so that when the solid body (7, 8) expands or deforms, a distance (A) between the active material (5) and the housing wall (3) is increased.

Inventors

  • Nikita Aurelian Schulz
  • Jan Teuwsen

Assignees

  • POWERCO SE

Dates

Publication Date
20260513
Application Date
20241108

Claims (7)

  1. Battery cell (1) comprising - a housing (2) with a housing wall (3) - a safety pressure valve (4) or a housing weak point arranged in the housing wall (3), - an active material (5) arranged inside the housing (2), characterized by - at least one solid body (7, 8) arranged in a space (6) between the housing wall and the active material (5), which only partially covers the housing wall (3), wherein the solid body (7, 8) expands or deforms when a limit temperature is exceeded, such that when the solid body (7, 8) expands or deforms, a distance (A) between the active material (5) and the housing wall (3) is increased.
  2. Battery cell (1) after Claim 1 , characterized in that the solid body (7, 8) is arranged laterally to the side of the safety pressure valve (4) or the housing weak point.
  3. Battery cell (1) after Claim 1 or 2 , characterized in that several of the solid bodies (7, 8) are arranged laterally to the side of the safety pressure valve (4) or the housing weak point.
  4. Battery cell (1) according to one of the preceding claims, characterized in that the housing wall (3) is designed such that the distance (A) between the active material (5) and the housing wall (3) is increased by deformation of the housing wall (3).
  5. Battery cell (1) according to one of the preceding claims, characterized in that the solid body (7, 8) comprises or is formed from a shape memory material or a bimetal.
  6. Battery cell (1) according to one of the preceding claims, characterized in that the solid body (7, 8) has several through holes (9, 10).
  7. A method for creating a gas channel in a battery cell (1), wherein the battery cell comprises: - a housing (2) with a housing wall (3); - a safety pressure relief valve (4) or a housing weak point arranged in the housing wall (3); - an active material (5) arranged within the housing (2); - at least one solid (7, 8) arranged in a space (6) between the housing wall and the active material (5), which only partially covers the housing wall (3); and the method comprises: - heating (S1) the battery cell (1) to a temperature above a limit temperature; - expanding or deforming (S2) the solid (7, 8) upon exceeding the limit temperature; - increasing (S3) a distance (A) between the active material (5) and the housing wall (3) during the expansion or deformation of the solid (7, 8).

Description

The present invention relates to a battery cell in which, in the event of thermal runaway, a gas channel can be formed to drain gases that may be produced. Battery cells are susceptible to thermal runaway (TR). The gases produced during a thermal runaway cause deformation of the battery cell casing, as the degassing channels – designed to achieve high energy densities – are typically very small. This deformation weakens the material and can lead to casing failure in undesirable locations. The deformation also places mechanical stress on adjacent cells. DE 10 2021 132 874 A1 This relates to a cell separator for placement in a space between two battery cells of a motor vehicle battery, wherein the cell separator is at least partially elastically deformable, such that it adapts to changes in the geometry of the space caused by expansion and/or contraction of the battery cells in the first direction. This increases the propagation time in the event of a thermal runaway. The cell separator can be made of a shape-memory material. Another technical problem with thermal runaway is that battery cells or parts of a cell stack, due to expansion or pressure from gases, can press against a safety pressure relief valve or a weak point in the casing. This has negative consequences, such as blocking the safety pressure relief valve or the weak point in the casing, faster propagation times, or cell rupture at unintended locations. The object of the invention was to provide a battery cell that does not exhibit the aforementioned disadvantages and allows for the venting of gases generated during thermal runaway. Ideally, the mechanical stress on adjacent cells should also be reduced. A battery cell and a method according to the independent claims are specified. Further embodiments are specified in the dependent claims and this description. The invention relates to a battery cell comprising - a case, with a case wall - a safety pressure valve located in the housing wall or a housing weak point located in the housing wall, - an active material arranged inside the housing, - at least one solid body arranged in a space between the housing wall and the active material, which only partially covers the housing wall, wherein the solid expands or deforms when a limit temperature is exceeded, such that when the solid expands or deforms, the distance between the active material and the housing wall is increased. The invention ensures that, in the event of a thermal runaway, parts of the active material do not compress under the pressure of a hot gas and settle onto the safety pressure valve or the housing weak point, thus preventing blockage. Negative effects, such as faster propagation times or cell rupture at unintended locations, are thereby avoided or at least significantly reduced in likelihood. The invention specifically aims to keep open the area between the active material and the housing wall where the safety pressure valve or the housing weak point is located. A housing weak point is a point of weakness where the housing is breached when a defined internal pressure is exceeded. An opening is formed in the housing through which gas can escape. A housing weak point can be created, for example, but is not limited to, a sheet metal welded onto a housing opening, where the weld fails at a defined pressure. The fact that the solid only partially covers the housing wall means, in particular, that the solid only partially covers the housing wall in a longitudinal dimension and/or a lateral dimension. If a solid also has the aforementioned through-holes running from the active material to the housing wall, there is no coverage in the area of the through-holes. The housing wall is preferably a lower housing wall, also referred to as the bottom wall, or an upper housing wall, also referred to as the top wall. Preferably, the solid is arranged only in a space between the bottom wall and the active material and/or the solid is arranged only in a space between the lid wall and the active material are arranged. This means that there is no solid body in a space between a side wall and the active material. When positioning a shape memory material between stacks of an active material, as in DE 10 2021 132 874 A1 As described, the blockage of the safety pressure valve is not prevented. According to the current state of the art... DE 10 2021 132 874 A1 and the placement of a shape memory material between the stacks exerts an expansion force laterally, thus also on the neighboring stacks, but this does not solve the technical problem of the present invention. Active material is understood to be an arrangement consisting of at least cathodes, current collector layers, and separators. Anodes may also be present. Increasing the distance between the active material and the housing wall creates or enlarges a volume for venting gases towards the safety pressure valve or housing weak point. The space between the housing wall and the active material is in