BATTERY CELL ARRANGEMENT

Abstract

A battery cell assembly comprises a battery cell and a battery cell holder. The battery cell has a cell casing. The cell casing has an outer surface. The outer surface of the casing has a first plurality of grooves formed therein. The battery cell holder has a plurality of cell pockets. Each of the cell pockets has a wall. The wall has a wall surface. The wall surface has a second plurality of grooves that interact with the first plurality of grooves on the outer surface of the cell casing. The interaction of the first plurality of grooves on the cell casing with the second plurality of grooves on the wall of each cell pocket from the plurality of cell pockets prevents the battery cell from moving relative to the battery cell holder.

Description

INTRODUCTION

[0001] The present invention relates to a battery cell assembly and, more particularly, to a battery cell assembly comprising a battery cell and a battery support structure.

[0002] Such a battery cell arrangement is disclosed, for example, in DE 10 2019 210 765 A1. The battery cells have several grooves that engage with corresponding grooves in the battery support structure to prevent the battery cells from moving relative to the battery support structure. A similar battery cell arrangement is disclosed in US 2011 / 0 135 975 A1.

[0003] A rechargeable energy storage system (RESS), such as a battery, typically comprises one or more battery cells and a means for supporting or holding the battery cell. The battery cell typically consists of an anode material and a cathode material separated by an electrically insulating material. The battery may comprise many anode and cathode pairs separated by the insulating material. In one example of a battery cell, the anode material, separator material, and cathode material (however many there may be) are rolled into a roll, sometimes called a "jelly roll." The jelly roll is then inserted into a hollow metal shell or casing to protect the jelly roll from the environment. The casing also serves to contain an electrolyte fluid within and around the jelly roll. The battery cell is supported by a casing or the like.Typically, an adhesive is used to hold the battery cell in the housing.

[0004] A battery cell in a RESS may experience an uncontrolled thermal event known as thermal runaway propagation (TRP). During a TRP event, the battery cell temperature may increase, leading to a pressure increase. Rising temperature and pressure within the enclosure due to gas production can cause the enclosure seal to leak.

[0005] While current RESS systems serve their purpose, problems remain. Accordingly, a new and improved RESS is needed that incorporates a means of securing the battery cells within the support member or housing. Furthermore, a RESS is needed that incorporates battery cells with a means of absorbing a TRP event. SUMMARY

[0006] According to the invention, a battery cell arrangement is presented which is characterized by the features of claim 1. According to another aspect of the present invention, the battery cell assembly further comprises a thermal interface material disposed between each of the plurality of cooling channels and the outer surface of the cell casing of the battery cell to promote heat transfer from the battery cell to the plurality of cooling channels.

[0007] According to another aspect of the present invention, the cell casing of the battery cell further comprises first and second ends, wherein a first plurality of the first plurality of grooves is formed in the cell casing surface at the first end of the cell casing and a second plurality of the first plurality of grooves is formed in the cell casing surface at the second end of the cell casing.

[0008] According to another aspect of the present invention, the cell housing further comprises a first wall portion, wherein the first wall portion has a first wall thickness and wherein the first plurality of grooves are formed in the first wall portion.

[0009] According to another aspect of the present invention, the cell housing further comprises a second wall portion, wherein the second wall portion has a second wall thickness, and wherein the second wall thickness is less than the first wall thickness of the first wall portion.

[0010] According to another aspect of the present invention, the second wall thickness of the second wall portion is arranged at the first or second end of the cell housing.

[0011] According to another aspect of the present invention, the wall of each cell pocket of the plurality of cell pockets has a first and a second end, wherein a first plurality of the second plurality of grooves is formed on the surface of the wall at the first end of each cell pocket of the plurality of cell pockets and a second plurality of the second plurality of grooves is formed on the surface of the wall at the second end of each cell pocket of the plurality of cell pockets.

[0012] According to another aspect of the present invention, the battery cell holder further comprises a projection extending from one of the first and second ends of the battery cell holder, and wherein the projection and the end of the housing define a vent gas passage.

[0013] According to yet another aspect of the present invention, the battery cell holder further comprises a projection extending from the first or second end of the battery cell holder. The projection and the end of the housing form a vent gas passage. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The drawings described herein are for illustrative purposes only. Fig. 1 and Fig. 2 show a battery cell assembly in a perspective view and a plan view, illustrated in accordance with the present invention. Fig. 3 shows the battery cell arrangement as shown in Fig. 2, in a cross-sectional view, illustrated according to the present invention. Fig. Figure 3A shows the first plurality of grooves formed in the housing outer surface and the plurality of grooves formed in the cell pocket wall as shown in Fig. 3, according to the present invention in an enlarged view. Fig. 3B shows the second plurality of grooves formed in the housing outer surface and a second plurality of grooves formed on the surface of the wall at the second end of each cell pocket of the plurality of cell pockets according to the present invention in an enlarged view. DETAILED DESCRIPTION

[0015] The following description is for illustrative purposes only.

[0016] With reference now to Fig. 1 and Fig. 2 illustrates a battery cell assembly 10 according to the present invention in a perspective view and a partial plan view. The battery cell assembly 10 includes a battery cell 12 and a battery cell holder 14. Although the battery assembly 10 is shown only in partial view, one skilled in the art will appreciate that the battery assembly 10 can be constructed in various sizes with the features described below, as required for the particular application. The battery cell 12 has a generally cylindrical shape and a hollow cylindrical cell housing 16.A jelly roll or Swiss roll construction or assembly may be used to manufacture the battery cell 12, in which an insulated plate (not shown) is disposed on one surface, a thin layer of anode material (not shown) is disposed on the insulated plate, a separator (not shown) is disposed on the anode material, and a cathode material (not shown) is disposed on the separator. The jelly roll assembly forms a cylindrical rechargeable battery made of, for example, the following materials: nickel cadmium (Ni-Cd), nickel metal hydride (NiMH), and lithium ion (Li-ion). The jelly roll assembly (not shown) is inserted into the hollow cylindrical cell casing 16. The cell casing 16 is sealed, and metal contacts (not shown) are attached. A variety of devices, such as electric motors, may be powered by the battery cell 12 by connecting electrical wires from the device (i.e., the battery cell).i.e. the electric motor) to the metal contacts of the battery cell 12.

[0017] A polymer, such as nylon, or other suitable material may be used to manufacture the cell holder 14. Furthermore, any suitable manufacturing method may be used to form the cell holder 14 using the polymer, such as injection molding, 3D printing, vacuum forming, and the like. The battery cell holder 14 includes a plurality of cell pockets 22. The cell pockets 22 are generally cylindrical in shape and are configured to hold a battery cell 12 within each of the cell pockets 22, as described in more detail below. In particular, each of the cell pockets 22 includes a pocket wall 24. The pocket wall 24 includes a pocket wall surface 26. The pocket wall 24 and the pocket wall surface 26 serve to hold or support the battery cell 12 and to facilitate cooling of the battery cell 12, as described in more detail below.

[0018] The battery cell holder 14 further includes a plurality of substantially flat and longitudinally extending cooling bands 32 that absorb the heat generated by the battery cells 12 and transport it to a location external to the battery assembly 10. The cooling bands 32 extend the entire length of the cell holder 14, and each of the cooling bands runs adjacent to or is aligned adjacent to each of the cell pockets 22. Each of the cooling bands 32 is made of a thermally conductive material, such as a metal. The cooling band 32 is made of aluminum, for example. The cooling bands 32 can be molded or overmolded into the battery cell holder 14 during the molding process of the battery cell holder 14.However, an opening or window 33 is provided in the pocket wall 24 adjacent to the cooling belt 32 to allow heat transfer from the battery cell 12 located in the cell pocket 22 to the cooling belt 32, as described in more detail below. Other methods for placing or positioning the cooling belts 32 in the cell holder 14 are also conceivable in the present invention; for example, the cooling belts 32 can be threaded through slots in the cell holder 14.

[0019] With additional reference to Fig. 3, the battery cell arrangement 10 is arranged on a Fig. 2 according to the present invention in a cross-sectional view. The cooling belts 32 have a plurality of cooling channels 34. Heat exchange fluid or coolant, such as ethylene glycol, diethylene glycol, propylene glycol, or polyalkylene glycol or a similar fluid, is circulated through each of the plurality of cooling channels 34 disposed in the pocket wall 24 of each of the plurality of cell pockets 22. The coolant circulating through the cooling channels 34 absorbs the heat generated by the battery cell 12 and transports it to a location external to the battery cell assembly 10, thereby cooling the battery cells 12.Additionally, a thermal interface material 36 is provided between each of the cooling bands 32 and the outer casing surface 18 of the cell casing 16 of the battery cell 12, disposed within the opening or window 33 in the wall 24 to further promote heat transfer from the battery cell 12 to the coolant in the plurality of cooling channels 34. The present invention contemplates the use of commercially available thermal interface materials cut or formed into a sheet or layer, such as a thermally conductive acrylic interface pad offered by 3M™. In the present invention, the thermal interface material 36 contacts the outer casing surface 18 of the cell casing 16 of the battery cell 12 and a surface of the cooling bands 32. The cooling bands 32 may be connected to a heat exchanger (not shown) that dissipates heat absorbed by the coolant in the cooling channels 34.

[0020] As in Fig. 3, the cell casing 16 of the battery cell 12 has a casing outer surface 18. The casing outer surface 18 has a plurality of grooves 20 formed therein, as shown in the expanded or enlarged views of Fig. 3A and Fig. 3B. The cell casing 16 of the battery cell 12 further includes first and second ends 38, 40. A first plurality 42 of the plurality of grooves 20 is formed in the cell casing surface 18 at the first end 38 of the cell casing 16, and a second plurality 44 of the plurality of grooves 20 is formed in the cell casing surface 18 at the second end 40 of the cell casing 16.

[0021] In addition, the cell housing 16 further includes a first wall portion 48. The first wall portion 48 has a first wall thickness "t1." The second plurality of grooves 44 are formed in the first wall portion 48, as shown in the expanded or enlarged view of Fig. 3B. The cell housing 16 also includes a second wall portion 50. The second wall portion 50 has a second wall thickness "t2." The second wall thickness t2 is less than the first wall thickness t1 of the first wall portion 48. While the second wall portion 50 is shown at the second end 40 of the cell housing 16, the present invention contemplates that the second wall portion 50 may be disposed at the first end 38 or at the second end 40 of the cell housing 16. The second wall thickness t2 is configured to allow one end or bottom 66 of the cell housing 16 to be separated from the remainder of the cell housing to allow gas that has accumulated within the cell housing to escape.

[0022] With further reference to Fig. 3, the wall 24 of each cell pocket of the plurality of cell pockets 22 of the cell holder 14 has a first end and a second end 52, 54. The wall surface 26 of the wall 24 has a second plurality of grooves 30 that cooperate with the first plurality of grooves 20 on the outer surface 18 of the cell housing 16. In particular, the second plurality of grooves 30 includes a first set of grooves 56, as shown in the expanded or enlarged view of Fig. 3A formed on the surface 26 of the wall 24 at the first end 38 of each cell pocket of the plurality of cell pockets 22, and a second set of grooves 58 formed on the surface 26 of the wall 24 at the second end 40 of each cell pocket of the plurality of cell pockets 22, as shown in the expanded or enlarged view of Fig.3B. The cooperation of the first plurality of grooves 20 on the cell housing 16 with the second plurality of grooves 30 on the wall 24 of each cell pocket of the plurality of cell pockets 22 prevents the battery cell 12 from moving relative to the battery cell holder 14. With the present invention, it is contemplated to adjust the number of grooves 20, 30 to provide retention forces sufficient to retain the battery cell 12 in the cell pocket 22 of the battery holder 14. For example, the number of grooves in the cell housing 16 and in the wall 24 of the cell holder 14 may be increased to increase the retention forces that hold the battery cell 12 in the battery cell holder 14.

[0023] The wall 24 additionally includes a plurality of protrusions 68 extending from the first or second end 52, 54 of the battery cell holder 14. The plurality of protrusions 68 at the end 54 of, for example, the cell casing 16 form a vent gas passage 70. During a temperature rise of the battery cell 12, referred to as a TRP event, gas accumulating in the battery casing can escape into the vent gas passage 40 through the separation of the cell casing 16 at the reduced wall thickness t2 in the wall portion 50 of the wall 24.

[0024] The present invention also relates to a method for assembling the battery cell 12. The method includes a first step in which a stamping process is performed. A second step includes a deep drawing process to extend the cylindrical battery case 16. A third step includes extending the cylindrical battery case 16 to an appropriate length. A fourth step includes a grooving process on the elongated cylindrical battery case to form the grooves in the case, for example, at the ends of the case. A fifth step includes inserting the jelly roll with an anode and cathode collector into the case. A sixth step includes filling the case with the electrolyte. A seventh and final step includes crimping one end onto the case to create a sealed battery case 16.

[0025] The present invention has many advantages and conveniences over current designs. For example, the cooperation of the plurality of grooves 20 in the battery cell 12 with the plurality of grooves 30 in the battery cell holder 14 minimizes the movement of the cell in the vertical axis compared to previous designs. Furthermore, the plurality of grooves 20, 30 also centers the battery cell 12 in the cell pocket 22 of the battery cell holder 14. In addition, the minimal movement of the vertical axis of the battery cell 12 in the cell pocket 22 also minimizes bending of the cell connectors or metal contacts. Furthermore, the assembly of the battery cells 12 in the battery cell holder 14 is simpler and more precise than compared to current designs.For example, a set or a plurality of battery cells 12 can be inserted into the battery cell holder 14 simultaneously using a series of suction cups attached to rotating arms, which in turn are attached to a robot arm or arms. The rotating arms can, for example, be capable of rotating in multiple directions, i.e., roll, yaw, and pitch, to enable efficient assembly of the battery cells 12 in the battery cell holder 14.

Claims

[1] Battery cell assembly (10) comprising: a battery cell (12) having a cell housing (16), wherein the cell housing (16) has a housing outer surface (18) and wherein the housing outer surface (18) has a first plurality of grooves (20) formed therein, a battery cell holder (14) made of a polymer material having a plurality of cell pockets (22), each of the cell pockets (22) having a wall (24) and the wall (24) having a wall surface (26), the wall surface (26) having a second plurality of grooves (30) that cooperate with the first plurality of grooves (20) on the outer surface (18) of the cell housing (16), and wherein the cooperation of the first plurality of grooves (20) on the cell housing (16) with the second plurality of grooves (30) on the wall (24) of each cell pocket (22) of the plurality of cell pockets (22) prevents the battery cell (12) from moving relative to the battery cell holder (14); wherein the battery cell holder (14) comprises a plurality of metal cooling bands (32) extending the entire length of the cell holder (14), each cooling band (32) extending adjacent to or aligned adjacent to each of the cell pockets (22) within the associated wall (24) to absorb heat generated by the battery cells (12) and transport it to a location external to the battery assembly (10); wherein the cooling belts (32) each have a plurality of cooling channels (34) in which a coolant circulates; and wherein a window (33) is formed in the wall (24) of each cell pocket (22), in which window a heat-conducting material (36) is located, which promotes the heat transfer from a battery cell (12) located in the respective cell pocket (22) and the cooling channel (34) in the wall (24). [2] The battery cell assembly (10) of claim 1, wherein the thermally conductive material (36) is disposed between each of the plurality of cooling channels (34) and the outer surface (18) of the cell casing (16) of the battery cell (12) to promote heat transfer from the battery cell (12) to the plurality of cooling channels (34). [3] The battery cell assembly (10) of claim 1, wherein the cell casing (16) of the battery cell (12) further comprises first and second ends (38, 40), a first plurality of the first plurality of grooves (20) being formed in the cell casing surface (18) at the first end (38) of the cell casing (16) and a second plurality of the first plurality of grooves (20) being formed in the cell casing surface (18) at the second end (40) of the cell casing (16). [4] The battery cell assembly (10) of claim 3, wherein the cell housing (16) further comprises a first wall portion (48), the first wall portion (48) having a first wall thickness, and the first plurality of grooves (20) formed in the first wall portion (48). [5] The battery cell assembly (10) of claim 4, wherein the cell housing (16) further comprises a second wall portion (50), wherein the second wall portion has a second wall thickness, and wherein the second wall thickness is less than the first wall thickness of the first wall portion (48). [6] Battery cell assembly (10) according to claim 5, wherein the second wall thickness of the second wall portion (50) is arranged at the first or second end (38, 40) of the cell housing (16). [7] The battery cell assembly (10) of claim 5, wherein the wall (24) of each cell pocket (22) of the plurality of cell pockets (22) has a first and a second end (52), wherein a first plurality of the second plurality of grooves (30) is formed on the surface of the wall (24) at the first end (52) of each cell pocket (22) of the plurality of cell pockets (22), and a second plurality of the second plurality of grooves (30) is formed on the surface of the wall (24) at the second end (54) of each cell pocket (22) of the plurality of cell pockets (22). [8] The battery cell assembly (10) of claim 1, wherein the battery cell holder (14) further comprises a projection (68) extending from one of the first and second ends of the battery cell holder (14), and wherein the projection (68) and the end of the housing define a vent gas passage (70).

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