Production Method for Battery Pack Thermal Insulation Pads

Abstract

Method of making a plurality of anti-thermal propagation cell spacers for use in a multi-cell battery pack comprising providing a web of double sided tape, the first side of which is attached to a fir

Description

TECHNICAL FIELD The present invention relates to a method of production of a thermal insulator for use in a battery pack. BACKGROUND In recent years, the popularity of electric vehicles has increased considerably. A main advantage of electric vehicles over traditional internal combustion engine vehicles is that they use electrical energy and so do not need to burn hydrocarbon-containing fuels. Consequently, electric vehicles do not emit carbon dioxide while driving and so are viewed as more environmentally friendly. Most electric vehicles comprise a sizeable battery pack with a plurality of chargeable lithium-ion batteries. Considerable time and effort goes towards designing this battery pack to be relatively small and lightweight, while providing a high energy storage capacity that allows the vehicle to be driven over large distances without requiring the batteries to be recharged. An important challenge in the design of battery packs for electric vehicles is to combine high density energy storage and quick charging with effective thermal management to avoid overheating of individual battery cells which can propagate to neighbouring battery cells and eventually lead to thermal runaway of larger parts of the battery pack. Known solutions for avoiding such thermal runaway include the use of thermally insulating material between adjacent battery cells. This thermally insulating material can be provided in the form of an anti-thermal propagation (ATP) pad, which consists of insulation material housed in a frame, with adhesive tape provided for bonding the ATP pad to a battery cell. Conventional methods of manufacturing these ATP pads utilise “pick and place” assembly, whereby the separate elements (insulation material, frame, and adhesive tape) are produced independently as pre-made parts before assembly into the ATP pad configuration. Manufacturing the elements of the ATP pads separately is a costly exercise whether it is done in-house along with the final assembly, or by an external supplier. In addition to the equipment required to assemble the final ATP pad, a large amount of machinery is required to produce these separate elements from raw and intermediate materials. In addition to this, if the individual components are produced by an external supplier and purchased for assembly into the ATP pads, the supply chain is made more complex and therefore more susceptible to changes and disruptions. This can affect the cost and quality of the final ATP pads, and may impact assembly if one or more components are temporarily unavailable. It is an aim of the present invention to address one or more disadvantages associated with the prior art. SUMMARY OF THE INVENTION According to an aspect of the invention, there is provided a method of making a plurality of anti-thermal propagation cell spacers for use in a multi-cell battery pack. The method comprises providing a first web of double-sided tape. A first side of the first web of double-sided tape is releasably attached to a first liner. The method also comprises kisscutting the first web of double-sided tape to define a first ladder-shaped waste matrix and a plurality of first adhesive patches, while the first liner remains uncut. The method further comprises removing the first ladder-shaped waste matrix from the first liner, while the first adhesive patches remain releasably attached to the first liner. The method further comprises providing a plurality of frames comprising a first face, a second face and a central aperture. The frames have an outer perimeter corresponding to an outer perimeter of the first adhesive patches. The frames also have an inner perimeter defined by the central aperture. The method even further comprises forming a plurality of insulation pads from a web of thermally insulating material. The insulation pads comprise a first face and a second face. The insulation pads have an outer perimeter corresponding to the inner perimeter of the frames. The method also comprises fitting together the frames and respective ones of the insulation pads such that the outer perimeter of the insulation pads is located within the central aperture of the frames. The method further comprises attaching the first face of the frames to respective ones of the first adhesive patches while the first adhesive patches are still attached to the first liner. The outer perimeter of the frames is aligned with the outer perimeter of respective ones of the first adhesive patches. The method further comprises attaching the first face of the insulation pads to respective ones of the first adhesive patches while the first adhesive patches are still attached to the first liner. The method may comprise providing a second web of double-sided tape. A first side of the second web of double-sided tape may be releasably attached to a second liner. The second web of double-sided tape may be kiss-cut to define a second ladder-shaped waste matrix and a plurality of second adhesive patches, while the second liner remains uncut. The second adhesive patches may have an outer perimeter corresponding to the outer perimeter of the first adhesive patches. The second ladder-shaped waste matrix may be removed from the second liner, while the second adhesive patches remain releasably attached to the second liner. The second face of the frames may be attached to respective ones of the second adhesive patches while the second adhesive patches are still attached to the second liner, wherein the outer perimeter of the frames is aligned with the outer perimeter of respective ones of the second adhesive patches. The second face of the insulation pads may be attached to respective ones of the second adhesive patches while the second adhesive patches are still attached to the second liner. The method may also comprise cutting the first liner and the second liner across a width of the first liner and second liner and in a position between adjacent frames to separate the anti-thermal propagation cell spacers. Especially when compared to a traditional “pick and place” method of assembly, producing the anti-thermal propagation (ATP) cell spacers from webs of material in a continuous process allows for greater control over the manufacturing process in various ways. Having a continuous process which forms the individual components as well as producing the final ATP cell spacers allows for a high level of control over the dimensions of the different components. As the tolerance between these individual components (especially between the frames, the insulation pads, and the adhesive patches) may be very small, having this control over the dimensions of the components is advantageous to lower the risk of not being able to fit the individual components together. This reduces the likelihood of needing to discard defective components, which can be beneficial to the overall cost of manufacturing of the ATP cell spacers. Advantageously, the manufacturing cost of the ATP cell spacers when using a continuous process is lower than it would be if the individual components were manufactured using separate processes. Substantially more machinery would be required to manufacture each component separately, which translates to an increased cost per component and therefore an increased overall cost of the ATP cell spacers. In one embodiment, the following method steps are carried out in this order: forming a plurality of insulation pads; attaching the first face of the insulation pads to respective ones of the first adhesive patches; attaching the first face of the frames to respective ones of the first adhesive patches; and simultaneously attaching the second face of the frames to respective ones of the second adhesive patches and attaching the second face of the insulation pads to respective ones of the second adhesive patches. The insulation pads and the frames could instead be applied to the first adhesive patches in the reverse order, for example. Alternatively, the frames and the insulation pads may be fitted together prior to application to the first adhesive pad. By attaching both the insulation pads and the frames to the first adhesive patches and then to the second adhesive patches, while they are still attached to their respective liners, this allows for many ATP cell spacers to be created in series, while one or both of the liners act as a carrier for moving the ATP cell spacers through the manufacturing process. This allows for a high level of control of the space between the ATP cell spacers throughout the manufacturing process This can help to mitigate misalignment between components as they are created and placed. In one embodiment, forming the plurality of insulation pads from the web of thermally insulating material may comprise feeding the web of thermally insulating material between a rotary die and a vacuum anvil roller. The rotary die may comprise a blade arrangement corresponding to the outer perimeter of the insulation pads. The blade arrangement and the vacuum anvil roller may contact the web of thermally insulating material. The blade arrangement may cut the web of thermally insulating material to define a third ladder-shaped waste matrix and the plurality of insulation pads, and subsequently the second face of the insulation pads is releasably attached to an outer surface of the vacuum anvil roller by a vacuum during a portion of a rotation of the vacuum anvil roller. Alternatively, the blade arrangement may cut the web of thermally insulating material to define the plurality of insulation pads. In one embodiment, attaching the first face of the insulation pads to respective ones of the first adhesive patches comprises releasing the vacuum when the vacuum anvil roller has completed the portion of a rotation. The insulation pads are vertically are preferably aligned with the respective ones of the first adhesive patches at the completion of the portion of a rotation. It is advantageous to form the insulation pads from a roll of thermally insulating material instead of using pre-cut insulation pads, particularly by using a rotary die and vacuum roller arrangement. Feeding pre-cut insulation pads into position onto the adhesive patches (for example, via a pick and place system) while the process is travelling at speed is a complex process, requires the process to start and stop, and there is a risk of misaligning the pre-cut insulation pads with the adhesive patches. By aligning the in-feed speed of the roll of insulation material with the speed that the adhesive patches travel through the process, the ATP cell spacer production machinery can run continuously. This means that the vacuum anvil roller rotates at the same speed as the adhesive tape to place the insulation pads onto the adhesive patches continuously without having to start and stop the process, leading to a higher production rate. The rotary die and vacuum roller arrangement can also be positioned so that after the insulation pads have been formed, they are immediately aligned with the adhesive patches, which minimises the risk of misalignment once they are placed into position. Alternatively, forming the plurality of insulation pads from the web of thermally insulating material may comprise die-cutting the web of thermally insulating material with a laser or a knife, to define a third ladder-shaped waste matrix and the plurality of insulation pads. The web of thermally insulating material may comprise a plurality of rolls of thermally insulating material, wherein the rolls of thermally insulating material are spliced together, defining a series of splices therebetween. The method may therefore also comprise determining a location of a splice of the series of splices using a sensor, and when the splice is proximate to the rotary die: disengaging the rotary die and moving the rotary die away from the web of thermally insulating material such that the blade arrangement does not contact the web of thermally insulating material, indexing the web of thermally insulating material forwards until the splice has passed the rotary die, and moving the rotary die towards the web of thermally insulating material such that the blade arrangement recontacts the web of thermally insulating material, and reengaging the rotary die. Splicing together rolls of thermally insulating material and then bypassing this splice, especially when combined with the use of an accumulator, is advantageous as it allows for a more smooth manufacturing process without the need to start and stop the process to load new rolls of material. Frequent starting and stopping of production can stretch and retract the webs of material, which in turn can negatively affect registration between parts of the machine. The method may further comprise removing a portion of the first liner to provide a plurality of first peel tabs, wherein the first peel tabs are aligned with the first adhesive patches. Similarly, the method may also comprise removing a portion of the second liner to provide a plurality of second peel tabs, wherein the second peel tabs are aligned with the second adhesive patches. The first liner may comprise polyethylene terephthalate. Similarly, the second liner may comprise polyethylene terephthalate. The provision of peel tabs allows for the liners to be more easily removed by the end user when applying the ATP cell spacers to battery cells. In one embodiment, the method may further comprise printing information onto the second face of the insulation pads or onto the PET release liner. Kiss-cutting of the first web of double-sided tape may comprise feeding the first web of double-sided tape through a first die cutter. Similarly, kiss-cutting of the second web of double-sided tape may comprise feeding the second web of double-sided tape through a second die cutter. BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 shows an exploded view of an embodiment of an anti-thermal propagation cell spacer according to the invention. Figures 2a and 2b show a top and front view respectively of another embodiment of an anti-thermal propagation cell spacer according to the invention. Figure 2c shows an exploded front view of the anti-thermal propagation cell spacer as shown in Figures 2a and 2b. Figure 3 shows an embodiment of a process for making an anti-thermal propagation cell spacer according to the invention. Figure 4 shows a perspective view of the process for making an anti-thermal propagation cell spacer as shown in Figure 3. Figure 5 shows the rotary die and vacuum roller arrangement from the process of Figures 3 and 4 during formation and placement of the plurality of insulation pads. Figure 6 shows the rotary die and vacuum roller arrangement from the process of Figures 3 and 4 during bypass of a splice. DETAILED DESCRIPTION OF THE DRAWINGS Figure 1 shows an exploded view of an embodiment of an anti-thermal propagation (ATP) cell spacer 100 according to the invention. The ATP cell spacer 100 is configured to be sandwiched between two battery cells (not shown) in a multi-cell battery pack. This provides thermal insulation between battery cells and helps to prevent thermal runaway. The ATP cell spacer 100 comprises a first liner 110, a first adhesive patch 120, a frame 130, an insulation pad 140, a second adhesive patch 150, and a second liner 160. It is to be noted that the Figures are schematic drawings and have not been drawn to scale. The insulation pad 140 is made of a lightweight insulation material configured for preventing thermal runaway. The lightweight insulation material may, for example, be an aerogel. Other suitable insulating materials may also be used. The insulation pad 140 has a first face 142, a second face (not shown), and an outer perimeter which defines a substantially rectangular shape. The substantially rectangular shape of the insulation pad 140 is chosen align well with the shape of traditional battery cells so as to provide a maximum coverage of the battery cell with insulation material, however any other suitable shape for the insulation pad 140 may be used. The frame 130 surrounds the insulation pad 140 and provides structure to the ATP cell spacer 100. The frame 130 is made of a thermoplastic or thermosetting polymer. Another suitable material may also be used for the frame 130. The frame 130 has a first face 132, a second face (not shown), a central aperture, and an outer perimeter which defines a substantially rectangular shape. The central aperture is substantially the same shape and size as the outer perimeter of the insulation pad 140. This allows the insulation pad 140 to fit into the central aperture with either a fixed fit or a small clearance. A border is defined between the central aperture and the outer perimeter of the frame 130. The border is relatively thin compared to the width of the insulation pad 140 in order to maximise the surface area of the battery cell which can be covered by insulation material. The insulation pad 140 and frame 130 sit on substantially the same plane, and have a similar thickness. The insulation pad 140 may be slightly thicker than the frame 130. The frame 130 and the insulation pad 140 are sandwiched between a first adhesive patch 120 and a second adhesive patch 150. The adhesives patches help to secure the insulation pad 140 inside the frame 130. In doing so, if the insulation pad 140 is thicker than the frame 130 then the insulation pad 140 may be compressed slightly by the first adhesive patch 120 and the second adhesive patch 150. The adhesive patches 120, 150 also each provide a surface for the ATP cell spacer 100 which can be attached to a battery cell. The adhesive patches 120, 150 are flexible and therefore allow for the insulation pad 140 to compress when the ATP cell spacer 100 is sandwiched between two battery cells. In this embodiment, the adhesive patches 120, 150 are made of double-sided tape and so each of a first and second side of each adhesive patch is coated in an adhesive layer. However, single-sided tape may also be used. Alternatively, any suitable material with an adhesive layer may be used for the adhesive patches. The adhesive patches 120, 150 both have outer perimeters with substantially the same shape and dimensions as the outer perimeter of the frame 130. In this embodiment, the adhesive patches 120, 150 are rectangular. The first side of the first adhesive patch 120 is attached to both the first face 132 of the frame 130 and the first face 142 of the insulation pad 140, so that the outer perimeters of the frame 130 and the first adhesive patch 120 are substantially aligned. The first side of the second adhesive patch 150 is attached to both the second face of the frame 130 and the second face of the insulation pad 140 in a similar manner. A first liner 110 and a second liner 160 are removably attached to the second side of the first adhesive patch 120 and the second adhesive patch 150 respectively, in order to protect each adhesive layer on the second side of the adhesive patches 120, 150. The liners 110, 160 are peeled away from the adhesive patches 120, 150 to expose the adhesive layers before application of the ATP cell spacer 100 to a battery cell (not shown). The first liner 110 may, for example, comprise polyethylene terephthalate. Likewise, the second liner 160 may, for example, comprise polyethylene terephthalate. Other suitable materials may also be used for the first liner 110 and the second liner 160. In some embodiments, the liners 110, 160 may have peel tabs which help a user to remove the liners 110, 160 from their corresponding adhesive patches 120, 150. As is shown in the embodiment of Figure 1, the first liner 110 has two first peel tabs 112, each positioned at opposite ends of the ATP cell spacer 100. Similarly, the second liner 160 has two second peel tabs 162, each positioned at opposite ends of the ATP cell spacer 100 and aligned with the first peel tabs 112. Figures 2a, 2b, and 2c show another embodiment of an anti-thermal propagation (ATP) cell spacer 100 according to the invention. While the ATP cell spacer 100 of Figure 1 is shown in an exploded view, the ATP cell spacer 100 of Figures 2a and 2b is shown as being fully assembled. The ATP cell spacer 100 of Figure 2c is shown in an exploded view. The ATP cell spacer 100 shown in Figures 2a, 2b, and 2c differs from the ATP cell spacer 100 shown in Figure 1 in the configuration of the peel tabs 112, 162. As is shown in this embodiment, the first liner 110 has one first peel tab 112, and the second liner 160 has one second peel tab 162. The first and second peel tabs 112, 162 are positioned at opposite ends of the ATP cell spacer 100. Figures 3 and 4 show an embodiment of a process for making multiple antithermal propagation cell spacers according to the invention, also referred to as an ATP cell spacer manufacturing process. As will be described, the process is a continuous process which allows for many ATP cell spacers to be created in series and linked together, before separation into individual ATP cell spacers. It is to be noted that the steps of the process for making an anti-thermal propagation cell spacer as described below can occur in any sensible order, in which case the machinery shown in Figures 3 and 4 and described below can be rearranged accordingly. A first web of double-sided tape is provided in the form of a roll at a first input 250. The first web of double-sided tape comprises a first side and a second side, both sides being covered in an adhesive layer. The second side is releasably attached to a first liner web 114. The first web of double-sided tape is unwound and fed into a first nip feed 200. At this stage, the first web of double-sided tape is oriented so that the first side is facing upwards, and the first liner web 114 is on the underside of the double-sided tape. The first nip feed 200 and other nip feeds in the ATP cell spacer manufacturing process may be coated with a non-stick silicone layer or another polytetrafluoroethylene (PTFE) type later so that the exposed adhesive does not permanently bond to the nip feed. The first liner web 114 indexes throughout the ATP cell spacer manufacturing process by passing through a series of nip feeds as will be described below, beginning with the first nip feed 200. The skilled person will acknowledge that these nip feeds may be positioned in locations other than what is shown in Figures 3 and 4, and that alternative methods for indexing the first liner web 114 throughout the manufacturing process may also be used. For example, a conveyor belt or other conveying means may act as a surface upon which the first liner web 114 may index throughout the ATP cell spacer manufacturing process. The first nip feed 200 indexes the first liner web 114 (with the attached first web of double-sided tape) forwards into a first die cut station 220. Here, a first die kiss-cuts the first web of double-sided tape to define a series of first adhesive patches 120 and a first ladder-shaped waste matrix. The first web of double-sided tape could instead be kiss-cut using alternative methods, such as a knife cutting mechanism, roller die cutter mechanism, or laser cutter. At this stage, the first liner web 114 remains uncut. The first ladder-shaped waste matrix is removed from the first liner web 114. This can be done by a respooling unit or another appropriate mechanism. The first adhesive patches 120 remain releasably attached to the first liner web 114 and are spaced apart from one another along the length of the first liner web 114. The first liner web 114 advantageously acts as a carrier for moving the first adhesive patches 120 throughout the ATP cell spacer manufacturing process. The first liner web 114 (with the attached first adhesive patches 120) then passes through a second nip feed 202 into a first rotary die cutter 222. Here, a first edge of the first liner web 114 is castellated by the first rotary die cutter 222 to create a series of first peel tabs 112, examples of which are shown in Figures 1, 2a, 2b, and 2c. The first peel tabs 112 are positioned to align with corresponding first adhesive patches 120. The first rotary die cutter 222 can also be configured to castellate peel tabs into the second edge of the first liner web 114, or alternatively to trim one or both edges of the first liner web 114. The edge trim waste from the first liner web 114 is then removed, preferably to a spooling unit. As is shown in more detail in Figure 5, a second rotary die cutter 230 used to cut and place the insulation pads 140 onto the first adhesive patches 120 is stacked vertically above a support roller 238. The second rotary die cutter 230 comprises a rotary die 232 and a vacuum anvil roller 236. The vacuum anvil roller 236 is stacked vertically below the rotary die 232. The vacuum anvil roller 236 is stacked vertically above the support roller 238. In this embodiment, the second rotary die cutter 230 is located after the first rotary die cutter 222 in the ATP cell spacer manufacturing process. In this embodiment, two rolls of thermally insulating material are provided at a second input 252. A first roll of thermally insulating material is unwound and passes through an accumulator 260. When the first roll of thermally insulating material is unwound to a point where the end of the material becomes visible, it is spliced together with the beginning of a second roll of thermally insulating material, defining a splice 242 between the two rolls of thermally insulating material. As is known in the art, the accumulator 260 allows time for the two rolls of thermally insulating material to be spliced together, while not having to stop the downstream manufacturing process. The thermally insulating material which exits the accumulator 260 is hereafter referred to as the web of thermally insulating material 240. As each roll of thermally insulating material is used through the process, another replacement roll of thermally insulating material may be loaded into the second input 252, to extend the web of thermally insulating material 240. Each time a new roll of thermally insulating material is loaded into the second input 252 and spliced to the web of thermally insulating material 240, another splice 242 is defined. The web of thermally insulating material 240 is fed into a first insulation nip feed 244, which indexes the web of thermally insulating material 240 into the second rotary die cutter 230. The rotary die 232 comprises a blade arrangement 234 which is configured to cut the web of thermally insulating material 240 as it passes through the second rotary die cutter 230 to define a plurality of insulation pads 240 and a corresponding ladder-shaped waste matrix. A vacuum applied by the vacuum anvil roller 236 suctions the insulation pads 140 and the ladder shaped waste matrix to the vacuum anvil roller 236. The ladder shaped waste matrix is pulled away from the vacuum applied by the vacuum anvil roller 236 and out of the second rotary die cutter 230 by a second insulation nip feed 246. A first side of each insulation pad 140 is therefore still releasably attached to the vacuum anvil roller 236 while it rotates. The first liner web 114 (in the embodiment shown in Figures 3 and 4, the first liner web 114 at this stage has first peel tabs 112 and is still releasably attached to the first adhesive patches 120) indexes between the vacuum anvil roller 236 and the support roller 238. This movement of the first liner web 114 may be assisted by passing the web 114 through a third nip feed 204 as in shown in Figures 3 and 4. The first liner web 114 moves between the vacuum anvil roller 236 and the support roller 238 at a speed which correlates to the speed that the second rotary die cutter 230 produces and rotates insulation pads 140. More specifically, when the vacuum anvil roller 236 has rotated so that an insulation pad 140 is positioned to be proximal to and vertically aligned with the support roller 238, a first adhesive patch 120 will also be positioned to be vertically aligned with the insulation pad 140. At this point, the vacuum in the vacuum anvil roller 236 releases, allowing the insulation pad 140 to attach to the first adhesive patch 120. The insulation pad 140 is now placed substantially in the centre of the first adhesive patch 120. This leaves a strip of exposed adhesive surrounding the insulation pad 140, where the frame 130 will later be placed. Next, an inkjet 262 prints the second face of the insulation pads 140 with information. This information can relate to the date of manufacture, batch number, or other relevant information. Figure 6 shows the rotary die and vacuum roller arrangement from the process of Figures 3 and 4 during bypass of a splice. As is explained above, the web of thermally insulating material 240 has at least one splice 242 defined where two rolls of thermally insulating material have been spliced together. A sensor determines the location of a splice 242 as it nears the rotary die 232. When the splice 242 is proximate to the rotary die 232, the rotary die 232 is disengaged and moved away from the web of thermally insulating material 240 so that the blade arrangement 234 is no longer in contact with the web of thermally insulating material 240. The web of thermally insulating material 240 can now index forward until the splice 242 has passed through the rotary die 232. After the splice 242 has passed through the rotary die 232, the rotary die 232 then moves back towards the web of thermally insulating material 240 and reengages, such that the blade arrangement 234 is now back in contact with the web of thermally insulating material 240. While the splice 242 passes through the rotary die 232, the first liner web 114 slows to a stop. The first liner web 114 restarts movement once the rotary die 232 is reengaged. This process allows for splices 242 to be bypassed so that a splice 242 is not included in an insulation pad 140. Stopping the first liner web 114 during this process avoids the possibility of producing an ATP cell spacer 100 without an insulation pad 140. In this embodiment, frames 130 are placed onto the first adhesive patches 120 at a frame placement module 266, following the placement of the insulation pads 140. However, the frames 130 could be placed onto the first adhesive patches 120 prior to the placement of the insulation pads 140. The frame placement module 266 could comprise a pick and place mechanism, or any other suitable alternative method to attach the frames 130 to the first adhesive patches 120. The first liner web 114 (in the embodiment shown in Figures 3 and 4, the first liner web 114 at this stage is still releasably attached to the first adhesive patches 120, which in turn has the frames 130 and insulation pads 140 attached) indexes through the ATP cell spacer manufacturing process and passes through a passes through a fourth nip feed 206. The fourth nip feed 206 applies pressure to further secure the frames 130 and insulation pads 140 to the first adhesive patches 120. A second web of double-sided tape is provided in the form of a roll at a third input 254. The second web of double-sided tape comprises a first side and a second side, both sides being covered in an adhesive layer. The second side is releasably attached to a second liner web (not shown). The second web of double sided tape is unwound and fed into a fifth nip feed 208. At this stage, the second web of double-sided tape is oriented so that the first side is facing upwards, and the second liner web is on the bottom side of the double-sided tape. The fifth nip feed 208 indexes the second liner web (with the attached second web of double-sided tape) forwards into a second die cut station 224. Here, a second die kisscuts the second web of double-sided tape to define a series of second adhesive patches 150 and a second ladder-shaped waste matrix. The second web of double-sided tape could instead be kiss-cut using alternative methods, such as a knife cutting mechanism, roller die cutter mechanism, or laser cutter. At this stage, the second liner web remains uncut. The second ladder-shaped waste matrix is removed from the second liner web. This can be done by a respooling unit or another appropriate mechanism. The second adhesive patches 150 remain releasably attached to the second liner web and are spaced apart from one another along the length of the second liner web. The second liner web (with the attached second adhesive patches 150) then passes into a third rotary die cutter 226. The third rotary die cutter 226 comprises a rotary die, stacked on top of an anvil roller. The third rotary die cutter 226 is also stacked vertically above another support roller (not shown). In this embodiment, the third rotary die cutter 226 is located after the fourth nip feed 206 in the ATP cell spacer manufacturing process. A first edge of the second liner web is castellated by the third rotary die cutter 226 to create a series of second peel tabs 162, examples of which are shown in Figures 1, 2a, 2b, and 2c. The second peel tabs 162 are positioned to align with corresponding second adhesive patches 150. The third rotary die cutter 226 can also be configured to castellate peel tabs into the second edge of the second liner web, or alternatively to trim one or both edges of the second liner web. The edge trim waste from the second liner web is then removed, preferably to a spooling unit. After passing through the third rotary die cutter 226, the second liner web is fed between the anvil roller and the support roller. The first liner web 114 (in the embodiment shown in Figures 3 and 4, the first liner web 114 at this stage is still releasably attached to the first adhesive patches 120, which in turn has the frames 130 and insulation pads 140 attached) is simultaneously also fed between the anvil roller and the support roller. Both the second liner web and the first liner web 114 pass between the anvil roller and the support roller at a correlated speed, so that the second adhesive patches 150 are applied to the second faces of the frames 130 and the insulation pads 140. At this point in the manufacturing process, the various components have been 5 assembled as layers in the following order, hereafter referred to as a linked series of ATP cell spacers: the first liner web 114, followed by the first adhesive patches 120, followed by the frames 130 and the insulation pads 140, followed by the second adhesive patches 150, followed by the second liner web (not shown). The linked series of ATP cell spacers therefore comprises a series of ATP cell spacers which are joined by a continuous first 10 liner web 114 and a continuous second liner web. The linked series of ATP cell spacers is finally fed through a sixth nip feed 210 into a rotary sheeter 264. The rotary sheeter 264 uses a cutting knife to cut vertically through the first liner web 114 and the second liner web between each frame 130. This 15 separates the individual ATP cell spacers 100, examples of which are shown in Figures 1, 2a, 2b, and 2c. The rotary sheeter 264 may instead use a laser to cut through the first liner web 114 and second liner web.

Claims

1. A method of making a plurality of anti-thermal propagation cell spacers(100) for use in a multi-cell battery pack, the method comprising:providing a first web of double-sided tape, wherein a first side of the first web of double-sided tape is releasably attached to a first liner;kiss-cutting the first web of double-sided tape to define a first ladder-shaped waste matrix and a plurality of first adhesive patches (120), while the first liner remains uncut;removing the first ladder-shaped waste matrix from the first liner, while the first adhesive patches (120) remain releasably attached to the first liner;providing a plurality of frames (130) comprising a first face (132), a second face and a central aperture, the frames (130) having an outer perimeter corresponding to an outer perimeter of the first adhesive patches (120), the frames (130) having an inner perimeter defined by the central aperture;forming a plurality of insulation pads (140) from a web of thermally insulating material (240), the insulation pads (140) comprising a first face (142) and a second face, the insulation pads (140) having an outer perimeter corresponding to the inner perimeter of the frames (130);fitting together the frames (130) and respective ones of the insulation pads (140) such that the outer perimeter of the insulation pads (140) is located within the central aperture of the frames (130);attaching the first face of the frames (130) to respective ones of the first adhesive patches (120) while the first adhesive patches (120) are still attached to the first liner, wherein the outer perimeter of the frames (130) is aligned with the outer perimeter of respective ones of the first adhesive patches (120); andattaching the first face (142) of the insulation pads (140) to respective ones of the first adhesive patches (120) while the first adhesive patches (120) are still attached to the first liner.

2. A method as claimed in claim 1, further comprises:providing a second web of double-sided tape, wherein a first side of the second web of double-sided tape is releasably attached to a second liner;kiss-cutting the second web of double-sided tape to define a second ladder-shaped waste matrix and a plurality of second adhesive patches (150), while the second liner remains uncut, wherein the second adhesive patches (150) have an outer perimeter corresponding to the outer perimeter of the first adhesive patches (120);removing the second ladder-shaped waste matrix from the second liner, while the second adhesive patches (150) remain releasably attached to the second liner;attaching the second face of the frames (130) to respective ones of the second adhesive patches (150) while the second adhesive patches (150) are still attached to the second liner, wherein the outer perimeter of the frames (130) is aligned with the outer perimeter of respective ones of the second adhesive patches (150); andattaching the second face of the insulation pads (140) to respective ones of the second adhesive patches (150) while the second adhesive patches (150) are still attached to the second liner.

3. A method as claimed in claim 2, wherein the following method steps are carried out in this order:forming a plurality of insulation pads (140);attaching the first face (142) of the insulation pads (140) to respective ones of the first adhesive patches (120);attaching the first face (132) of the frames (130) to respective ones of the first adhesive patches (120); andsimultaneously attaching the second face of the frames (130) to respective ones of the second adhesive patches (150) and attaching the second face of the insulation pads (140) to respective ones of the second adhesive patches (150).

4. A method as claimed in claim 2 or 3, further comprising:cutting the first liner and the second liner across a width of the first liner and second liner and in a position between adjacent frames (130) to separate the anti-thermal propagation cell spacers (100).

5. A method as claimed in any preceding claim, wherein the forming of the plurality of insulation pads (140) from the web of thermally insulating material (240) comprises:feeding the web of thermally insulating material (240) between a rotary die (232) and a vacuum anvil roller (236), wherein the rotary die (232) comprises a blade arrangement (234) corresponding to the outer perimeter of the insulation pads (140), wherein the blade arrangement (234) and the vacuum anvil roller (236) contact the web of thermally insulating material (240);wherein the blade arrangement (234) cuts the web of thermally insulating material (240) to define a third ladder-shaped waste matrix and the plurality of insulation pads (140), and subsequently the second face of the insulation pads (140) is releasably attached to an outer surface of the vacuum anvil roller (236) by a vacuum during a portion of a rotation of the vacuum anvil roller (236).

6. A method as claimed in claim 5, wherein the attaching of the first face (142) of the insulation pads (140) to respective ones of the first adhesive patches (120) comprises releasing the vacuum when the vacuum anvil roller (236) has completed the portion of a rotation, wherein the insulation pads (140) are vertically aligned with the respective ones of the first adhesive patches (120) at the completion of the portion of a rotation.

7. A method as claimed in claim 5 or 6, wherein the web of thermallyinsulating material (240) comprises a plurality of rolls of thermally insulating material, wherein the rolls of thermally insulating material are spliced together, defining a series of splices (242) therebetween.

8. A method as claimed in claim 7, further comprising:determining a location of a splice (242) of the series of splices using a sensor, and when the splice (242) is proximate to the rotary die (232):disengaging the rotary die (232) and moving the rotary die (232) away from the web of thermally insulating material (240) such that the blade arrangement (234) does not contact the web of thermally insulating material (240);indexing the web of thermally insulating material (240) forwards until the splice (242) has passed the rotary die (232); andmoving the rotary die (232) towards the web of thermally insulating material (240) such that the blade arrangement (234) recontacts the web of thermally insulating material (240), and reengaging the rotary die (232).

9. A method as claimed in any preceding claim, further comprising removing a portion of the first liner to provide a plurality of first peel tabs (112), wherein the first peel tabs (112) are aligned with the first adhesive patches (120).

10. A method as claimed in any of claims 2 to 9, further comprising removing a portion of the second liner to provide a plurality of second peel tabs (162), wherein the second peel tabs (162) are aligned with the second adhesive patches (150).

11. A method as claimed in any preceding claim, further comprising printing information onto the second face of the insulation pads (140).

12. A method as claimed in any preceding claim, wherein the kiss-cutting of the first web of double-sided tape comprises feeding the first web of double-sided tape through a first die cutter (220).

13. A method as claimed in any of claims 2 to 12, wherein the kiss-cutting of the second web of double-sided tape comprises feeding the second web of double-sided tape through a second die cutter (224).

14. A method as claimed in any preceding claim, wherein the first liner comprises polyethylene terephthalate.

15. A method as claimed in any of claims 2 to 14, wherein the second liner comprises polyethylene terephthalate.

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