Search

EP-4654331-B1 - BATTERY MODULE WITH THERMAL INSULATION SPACERS

EP4654331B1EP 4654331 B1EP4654331 B1EP 4654331B1EP-4654331-B1

Inventors

  • VILLARDI, Caroline

Dates

Publication Date
20260513
Application Date
20240524

Claims (15)

  1. A battery module (10) comprising - two parallel end plates (12) and two parallel side plates (14) extending along a longitudinal direction (100) of the battery module (10) perpendicular to the end plates (12), wherein the end plates (14) and side plates (16) are made of an aluminium alloy with a thermal conductivity higher than 100 Wm -1 K -1 , - rows of cells (16) extending in the longitudinal direction (100) of the battery module (10), each of the rows of cells (16) comprising a series of prismatic battery cells (20, 22) and thermal insulation spacers (24, 26) repeated alternately along the longitudinal direction (100), - a partition plate (18) between each pair of adjacent rows among the rows of cells (16), each partition plate (18) extending parallel to the side plates (14), wherein the partition plates (18) are made of an aluminium alloy with a thermal conductivity higher than 100 Wm -1 K -1 characterised in that at least one of the thermal insulation spacers (24, 26) is made of a state transition material, which exhibits an initial thermal conductivity higher than an initial thermal conductivity threshold (TCT1) at temperatures below 200°C and, when exposed to temperatures higher than a transition temperature (TT) greater than 220°C and less than 320°C, undergoes an irreversible transformation which results in a post-transformation thermal conductivity lower than a post-transformation thermal conductivity threshold (TCT2) that is less than the initial thermal conductivity threshold (TCT1) minus 0.5 Wm -1 K -1 , and less than 0.28 Wm -1 K -1 ; and in that the thermal insulation spacers (24, 26) include intermediate insulation spacers (24) each located between and in contact with two adjacent prismatic battery cells (20, 22) of the series, and two opposite end insulation spacers (26) each at a respective longitudinal end of the series, each of the end insulation spacers (26) being in contact with a respective end prismatic battery cell (22) of the series and a respective one of the two end plates (12), wherein at least one of the two end insulation spacers (26) is made of said state transition material.
  2. The battery module (10) of claim 1, wherein - the initial thermal conductivity threshold (TCT1) is higher than 0.30 Wm -1 K -1 , and preferably higher than 0.35 Wm -1 K -1 ; and/or - the post-transformation thermal conductivity threshold (TCT2) is less than or equal to 0.25 Wm -1 K -1 ; and/or - the post-transformation thermal conductivity threshold (TCT2) that is less than the initial thermal conductivity threshold minus 0.8 Wm -1 K -1 - the transition temperature (TT) is greater than 280°C; and/or - the transition temperature (TT) is less than 300°C.
  3. The battery module (10) of any one of the preceding claims, wherein the initial thermal conductivity is higher than the initial thermal conductivity threshold (TCT1) at temperatures below 220°C.
  4. The battery module (10) of any one of the preceding claims, wherein the transformation comprises charring, which results in an outer char coating or a depth charring of said state transition material.
  5. The battery module (10) of any one of the preceding claims, wherein the state transition material consists of, or comprises one or more of: - a composite material which contains a polyolefin and glass or mineral fibres; and/or - a composite material which contains at least 60 wt. % of polypropylene and at least 20 wt. % of long glass fibres and 0.01 to 10 wt. % of a halogen-free flame retardant; and/or - a thermoplastic polymer composition comprising a flame retardant, preferably an intumescent flame retardant.
  6. The battery module (10) of any one of the preceding claims, wherein the state transition material exhibits a V 0 rating for a material thickness of 1 mm when tested in accordance with UL94.
  7. The battery module (10) of any one of the preceding claims, wherein the thermal conductivity of the end plates (12) and side plates (14) is higher than the thermal conductivity of the partition plates.
  8. The battery module (10) of any one of the preceding claims, wherein the intermediate insulation spacers (24) are made of an insulating material exhibiting a thermal conductivity which: - is less than 0.04 Wm -1 K -1 at temperatures below 350°C; and/or - is less than 0.05 Wm -1 K -1 at temperatures below 450°C; and/or - increases with the temperature in a temperature range from 100°C to 400°C.
  9. The battery module (10) of any one of the preceding claims, wherein each of the end plates (12) is made of a heat conductive material with a thermal conductivity higher than 100 Wm -1 K -1 , preferably an aluminium alloy.
  10. The battery module (10) of any one of the preceding claims, wherein the one or more rows of cells (16) include at least a first and a second rows of cells (16).
  11. The battery module (10) of claim 10, comprising a common end plate insulation spacer comprising the end insulation spacer (26) of the first row of cells (16) and the end insulation spacer (26) of the second row of cells.
  12. The battery module (10) of any one of claims 10 toll, wherein the first and second rows of cells (16) are positioned side by side on opposite sides of a partition plate (18) which extends from one of the two end plates (12) to the other.
  13. The battery module (10) of claim 12 in combination with claim 11, wherein the common end plate insulation spacer (26) is provided with a slot (28) through which a tongue (30) of the partition plate (18) extends.
  14. The battery module (10) of any one of claims 12 to 13, wherein - the partition plate (18) is made of an aluminium alloy with a thermal conductivity higher than 100 Wm -1 K -1 , and/or - each of the prismatic battery cells (20, 22) has a contact area with the partition plate (18), which is less than ¼ of a contact area between the end battery cell (22) and the end insulation spacer (26).
  15. The battery module (10) of any one of the preceding claims, wherein the least one of the thermal insulation spacers (24, 26) made of said state transition material has a thickness of more than 0,7mm and less than 2,5 mm.

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a battery module and, more specifically to provisions taken to address thermal propagation risks in a battery module. BACKGROUND ART Battery modules comprising two opposite end plates and several parallel rows of cells separated by one or more partition plates perpendicular to the end plates are well known in the art, as disclosed e.g. in CN111584978A or CN113437403A. Each row of cells usually comprises a repeating series of alternating prismatic battery cells and thermal insulation spacers. The thermal insulation spacers include intermediate insulation spacers each located between two adjacent prismatic battery cells of the series, in direct contact with the two adjacent prismatic battery cells, and two opposite end insulation spacers, each at a respective end of the series, in contact with an end battery cell of the series and with one of the end plates. Under normal operating conditions, there is an advantage in having a high thermal conductivity between the end battery cell and the end plate, so that heat can flow through the end plate rather than towards the next battery cell of the row. However, if the end battery cell overheats, too high a conductivity increases the risk of heat being transferred through the end plate to the end battery cell of the next row. Similarly, depending on the design of the battery module, it may be advantageous to promote heat flow between the cells of a row at low temperature, while avoiding heat propagation from an overheated cell to the neighbouring cells of the row. WO2023279096 discloses methods and systems to manage thermal runaway issues in energy storage systems. Exemplary embodiments include methods and systems having a compressible thermal barrier. The compressible thermal barrier is tailored in size (e.g., thickness, volume, etc.) to prevent thermal propagation between adjacent cells, modules and/or packs when a portion of an energy source has experienced a thermal event. The methods and systems mitigate thermal propagation such that a cell adjacent to a compromised cell (e.g., actively combusting cell) does not experience thermal runaway as it is shielded from dissipating heat and does not surpass a critical temperature. A battery module or pack with one or more battery cells and the compressible thermal barrier placed between adjacent cells are also disclosed. WO2023067071 discloses an article for covering battery components in an automotive prime-mover battery pack, the article comprising a top cover having an outer major surface and an inner major surface that is shaped to conform to the battery components, wherein the top cover is prepared by extrusion of a composition comprising a polyolefin and glass fibers to obtain a sheet and subsequent thermoforming of the sheet and wherein the article is configured to form an outer char coating when exposed to flame. WO2020064752 discloses a glass fiber filled flame retardant polypropylene composition comprising (A) a polypropylene-based polymer, (B) a first flame retardant in an amount of 15 to 40 wt% of the total composition, wherein the first flame retardant is in the form of particles comprising ammonium polyphosphate and at least one phosphate selected from the group consisting of melamine phosphate, melamine polyphosphate, melamine pyrophosphate, piperazine phosphate, piperazine polyphosphate, piperazine pyrophosphate, 2-methylpiperazine monophosphate, tricresyl phosphate, alkyl phosphates, haloalkyl phosphates, tetraphenyl pyrophosphate, poly(2-hydroxy propylene spirocyclic pentaerythritol bisphosphate) and poly(2,2-dimethylpropylene spirocyclic pentaerythritol bisphosphonate), (C) a second flame retardant in an amount of 0.1 to 15 wt% of the total composition, wherein the second flame retardant comprises an aromatic phosphate ester and (D) glass fibers in an amount of 5 to 40 wt% of the total composition. SUMMARY OF THE INVENTION The invention aims to provide a battery module which conciliate these contradictory requirements. According to the invention, there is provided a battery module comprising one or more rows of cells extending in a longitudinal direction of the battery module, each of the one or more rows of cells comprising a series of prismatic battery cells and thermal insulation spacers repeated alternately along the longitudinal direction. At least one of the thermal insulation spacers is made of a state transition material, which exhibits an initial thermal conductivity higher than an initial thermal conductivity threshold at temperatures below 200°C and, when exposed to temperatures higher than a transition temperature greater than 220°C and less than 320°C, undergoes an irreversible transformation which results in a post-transformation thermal conductivity lower than a post-transformation thermal conductivity threshold that is less than the initial thermal conductivity threshold minus 0.5 Wm-1K-1, and less than 0.28 Wm-1K-1 . The