High voltage battery module parallel cell fusing system

Abstract

A fusing system for a brick of lithium ion battery in a battery module is provided where the fusing system has a combination of low-voltage fuses and a high-voltage fuse. The low-voltage fuse can have one or more fusing elements in a springy spiral configuration or a straight configuration with the fuse element encapsulated.

Claims

1. A fusing system in a brick of battery cells comprising: a first terminal; a first cell interconnect coupled to the first terminal to receive a flow of current from said first terminal; a plurality of battery cells in said brick coupled to the first cell interconnect in parallel; a second cell interconnect coupled to the plurality of battery cells in parallel; a second terminal coupled to said second cell interconnect; wherein a majority of said plurality of battery cells are each coupled to the first cell interconnect via a low-voltage fuse; and wherein at least one of said plurality of battery cells is coupled to the first cell interconnect via a high-voltage fuse.

2. The fusing system as recited in claim 1, wherein the low voltage fuse has a contact portion and at least one arm, said contact portion makes a direct contact with one of said battery cell from said majority, and said at least one arm acts as the fusing element connecting the contact portion to the first cell interconnect.

3. The fusing system as recited in claim 2, wherein the at least one arm has a curved shape.

4. The fusing system as recited in claim 3, wherein the at least one arm has a spiral shape.

5. The fusing system as recited in claim 4, wherein the low voltage fuse has at least two arms in a double spiral configuration.

6. The fusing system as recited in claim 2, wherein the contact portion is not on a same plane as the first cell interconnect.

7. The fusing system as recited in claim 2, wherein the at least one arm has a springy property with a biasing force that tends to move the contact portion of the low voltage fuse away from the battery cell.

8. The fusing system as recited in claim 2, wherein the high-voltage fuse is a cartridge fuse and it minimizes arcing and thermal runaway events by providing sufficient creepage and clearance to prevent arcs from continuing to short to the plurality of battery cells or other ground metal.

9. The fusing system as recited in claim 8, wherein the low-voltage fuses are designed to melt before the high-voltage fuse.

10. The fusing system as recited in claim 9, wherein when the low-voltage fuse opens up, a gap is created with sufficient opening to allow a polluted gas to escape from a vicinity of the plurality of battery cells.

11. The fusing system as recited in claim 3, wherein the fusing element of the low-voltage fuse is encapsulated by silicone or silicone based composite encapsulant.

12. The fusing system as recited in claim 9, wherein the fusing element of the low-voltage fuse is encapsulated by silicone or silicone based composite encapsulant.

13. The fusing system as recited in claim 12, wherein break point of the fusing element is located within an interstitial space sandwiched between two dielectric layers of composite material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) It should be noted that the drawing figures may be in simplified form and might not be to precise scale. In reference to the disclosure herein, for purposes of convenience and clarity only, directional terms such as top, bottom, left, right, up, down, over, above, below, beneath, rear, front, distal, and proximal are used with respect to the accompanying drawings. Such directional terms should not be construed to limit the scope of the embodiment in any manner

(2) FIG. 1 is a perspective view of the contemplated fusing system implemented in a brick of battery cells, according to one aspect of the disclosure.

(3) FIG. 2 is a perspective view of the fusing system of FIG. 1 in a cell interconnect, according to one aspect of the disclosure.

(4) FIG. 3 is a top plan view of the fusing system of FIG. 2, according to one aspect of the disclosure.

(5) FIG. 4 is a bottom plan view of the fusing system of FIG. 2, according to one aspect of the disclosure.

(6) FIG. 5 is a close-up top plan view of a low-voltage fuse in the contemplated fusing system of FIG. 2, according to one aspect of the disclosure.

(7) FIG. 6 is a side perspective view of the low-voltage fuse of FIG. 5, according to one aspect of the disclosure.

(8) FIG. 7 is a side plan view of the low-voltage fusing system of FIG. 2, according to one aspect of the disclosure.

(9) FIG. 8 is a close-up side view of a low-voltage fuse of FIG. 5, according to one aspect of the disclosure.

(10) FIG. 9 is a close-up side view of a low-voltage fuse with its arms encapsulated in silicon, according to one aspect of the disclosure.

(11) FIG. 10 is a top plan view of the metal layer of a cell interconnect having a different design in the fusing element of the low-voltage fuses, according to one aspect of the disclosure.

(12) FIG. 11 is a bottom plan view of the metal layer of FIG. 10, according to one aspect of the disclosure.

(13) FIG. 12 is a close-up view of the low-voltage fuse shown in FIG. 10, according to one aspect of the disclosure.

(14) FIG. 13 is a close-up view of another embodiment of a low-voltage fuse having its fuse element encapsulated in silicon, according to one aspect of the disclosure.

(15) The following call-out list of elements in the drawing can be a useful guide when referencing the elements of the drawing figures:

(16) 1 Brick of battery cells

(17) 100 Fusing system

(18) 101 Top cell interconnect

(19) 102 Bottom cell interconnect

(20) 103 Dielectric layer

(21) 104 Terminal

(22) 105 Battery cell

(23) 106 Exposed metal

(24) 109 Electrically isolated patch

(25) 110 Low voltage fuse

(26) 112 Contact portion

(27) 114 Spiral arm

(28) 115 Encapsulant

(29) 116 Gap

(30) 120 High voltage fuse

(31) 121 Glass tube

(32) 122 First spring clamp

(33) 123 Second spring clamp

(34) 124 First end cap

(35) 125 Second end cap

(36) 126 First link contact

(37) 127 Second link contact

(38) 128 Conductive bridge

(39) 129 Ceramic tube

(40) 210 Low voltage fuse

(41) 212 Contact portion

(42) 214 Fuse element

(43) 215 Encapsulant

(44) 217 Gap

DETAILED DESCRIPTION OF THE DISCLOSURE

(45) The different aspects of the various embodiments can now be better understood by turning to the following detailed description of the embodiments, which are presented as illustrated examples of the embodiments as defined in the claims. It is expressly understood that the embodiments as defined by the claims may be broader than the illustrated embodiments described below.

(46) In a typical large high-voltage battery pack, there can be several lower voltage modules in series. Within each lower voltage battery modules there can have several “bricks” of batteries in series. Each brick can contain many lithium ion cells in parallel. The inventor has discovered a novel system and method of fusing a brick of battery cells. Although the embodiments herein are described with implementation in a brick of battery cells, it is particular contemplated that this novel system can be used in other types of cells and energy storage devices such as capacitors.

(47) This contemplated general concept provides that during a short or other disruptive events within a brick, further damage to the module can be kept under control by having N-1 number of fuse to melt first at low voltage and then the last fuse to melt at a high voltage using a commercially available high-voltage fuse with high interrupt current rating.

(48) There can be many causes of a short. For example, when an electric vehicle collides with a physical object, its battery pack may be physically damaged by blunt force and even the battery housing may be punctured. Such blunt force may also physically puncture a battery cell and/or a cell interconnect, thereby causing a short at or near the puncture site. In another example, a defected battery cell may overheat during a fast-charging session, leading to rupturing or a small explosion. This thermal event at the defected battery cell can lead to a thermal runaway event where neighboring battery cells also ruptures and explodes.

(49) Referring now to FIG. 1. Here, a brick 170 is shown having twenty-one battery cells 105. It should be noted that the contemplated fusing system can be implemented to a brick of any number of battery cells. This group of battery cells 105 are connected in parallel between a top cell interconnect 101 and a bottom cell interconnect 102. A cell interconnect is defined as a multi-layer material which can include an electrically conductive sheet material and sandwiched between two dielectric layers such as mica. Other dielectric materials like GPO1 GPO3 and FR4 can also be used. In FIG. 1, the top cell interconnect 101 itself is also labeled as the fusing system 100 because it contains the low-voltage cell fuses 110 and the high-voltage fuse 120. Here, the bottom cell interconnect 102 is also shown to have the contemplated fusing system 100.

(50) The contemplated fusing system 100, however, is not limited to necessarily require the cell interconnect 101, 102 or being part of the cell interconnect 101, 102. For example in one contemplated embodiment, the novel fusing system 100 can be a system of low-voltage fuses in combination with at least one high-voltage fuse in a battery module whether these fuses are specifically installed directly on the cell interconnect 101, 102 or elsewhere in the battery module.

(51) In one contemplated embodiment, a brick 170 can have the fusing system 100 implemented in either the top cell interconnect 101 or the bottom cell interconnect 102.

(52) In another contemplated embodiment, a brick 170 can have the fusing system 100 implemented in both the top cell interconnect 101 and the bottom cell interconnect 102.

(53) In the top cell interconnect 101 shown in FIG. 1, there are twenty low-voltage cell fuses 110. The remaining one battery cell not provided with a low-voltage cell fuse 110 is provided with a high-voltage fuse, as will be explained in more details later.

(54) Also shown in FIG. 1 is a terminal 104 on the exposed metal sheet 106 of the electrically conductive sheet material. Besides the exposed metal sheet 106, the rest of the top side of the top cell interconnect 101 is covered by mica or any other suitable dielectric material.

(55) Similarly, the side of the bottom cell interconnect 102 facing the battery cells 105 can also be mostly covered by mica or any other suitable dielectric material.

(56) While the cell interconnect 101, 102 are shown in a generally flat and rectangular shape, it should be noted that other shapes, sizes, and dimensions are also possible.

(57) Referring now to FIGS. 2-4. Here, the top cell interconnect 101 and all of the battery cells 105 have been removed leaving only the bottom cell interconnect 102. During normal operation, current flows from terminal 104 of one cell interconnect 101, 102 to the terminal 104 of the other cell interconnect 101, 102. Between these two terminals 104, the current goes through to the battery cells 105 (in parallel) via low-voltage cell fuses 110 and one high-voltage fuse 120.

(58) The top layer of the cell interconnect 102 can be a mica layer as mentioned above. Under the mica layer can be an electrically conductive layer. An exemplar design of this electrically conductive layer is shown in FIGS. 10 and 11. Most notably in FIGS. 10 and 11, there can be N-1 number of low-voltage fuses 210 directly connected to the exposed metal 106 of the electrically conductive layer. There can be an electrically isolated patch 109 formed along the edge on the far end opposite the terminal 104. This patch 109 is electrically isolated from rest of the exposed metal 106 and is electrically connected to the exposed metal 106 only via the high-voltage fuse 120. This electrically isolated patch 109 can be located elsewhere in the design of the metal layer so long as the same principle is followed to have N-1 number of battery cells each connected via a low-voltage fuse in parallel with one battery cell connected via a high-voltage fuse.

(59) Returning now to FIGS. 2-4, the terminal 104 can be directly provided on the electrically conductive layer. The electrically conductive layer can have twenty-one circular openings, each provided for a battery cell 105. Of the twenty-one circular openings, twenty of them are provided with a low-voltage cell fuse 110. The top mica layer has corresponding twenty-one circular openings in order to expose the low-voltage cell fuses 110.

(60) Of the twenty-one circular openings, one of them is provided with a conductive bridge 128 which is not directly connected to the electrically conductive layer. Instead, the conductive bridge 128 can be disposed on an electrically isolated patch (not shown) such as the one previously discussed in FIGS. 10 and 11. The conductive bridge 128 can be directly and electrically connected to link contact 127 which in turn electrically connects to end cap 125 of the high-voltage fuse. The end cap 125 is then electrically connected to a fusing element within the ceramic tube 129 and then electrically connected to end cap 124. End cap 124 is in turn electrically connected to link contact 126 which in turn is electrically connected to the electrically conductive layer of cell interconnect 102. Therefore, N-1 number of battery cells 105 in this arrangement is provided with a low-voltage fuse 110 while current must flow through high-voltage fuse 120 to get to the one remaining battery cell 105.

(61) It should be noted that the high-voltage fuse 120 can be a cartridge fuse that can be replaced. In other embodiments, a replaceable high-voltage fuse 120 may not be necessary because when a battery module fuses the module may become damaged forever, making it unnecessary to replace the fuse. Therefore, other permanent and cost-effective types of high-voltage fuses can be provided.

(62) This concept solves problems known with existing off-the-shelf parts and with current battery pack design practices. The high-voltage cell fuse 120 could have a lower cost than a known pack fuse, so it is conceivable that this strategy is a more robust fusing strategy than battery pack fusing strategies today.

(63) FIG. 4 shows the opposite side of the cell interconnect 102. This side of the cell interconnect can also be covered with mica. Here, a mica layer is provided. Conductive bridge 128 is not electrically connected to the whole sheet of electrically conductive layer except through the link contacts 126, 127 and the high-voltage fuse 120 as described above.

(64) FIGS. 5 and 6 show the low-voltage fuse 110 in close-up views. The low-voltage fuse 110 can have a contact portion 112 disposed in the middle of a circular opening. The contact portion 112 can be welded onto a battery cell 105. There can be two spiral arms 124 electrically connecting the contact portion 112 to the rest of the metal layer of the cell interconnect. In between the contact portion 112 and the end of the circular opening is the gap 116.

(65) Contemplated gap 116 can have a sufficient width to allow a polluted gas from the battery cells to escape to the opposite side of the cell interconnect 112, 113. Further, there can be provided vent holes or other ventilation means to further transport the polluted gas away from the battery cells 105. The inventor has discovered that the polluted gas can become a trigger for a thermal runaway event if such polluted gas is allowed to reach neighboring battery cells 105. Therefore, one specific embodiment offers sufficient gap distance between the contact portion 112 and the edge of the circular opening. In another embodiment which will be discussed in more details in FIGS. 8 and 9, this gap 116 can be created by a contact portion 112 that is vertically offset from the main plane of the cell interconnect 102.

(66) Referring now to FIG. 7, one particular embodiment of cell interconnect 102 is shown. Here, the contact portions 112 can be seem vertically offset from the general plane of the cell interconnect 102 at rest. In another embodiment, the contact portions 112 are not vertically offset from the general plane of the cell interconnect 102 at rest. Instead, during assembly of a brick 1 of battery cells, the contact portions 112 can be biased away from the general plane of the cell interconnect 102 (such as that shown in FIGS. 8 and 9) and welded onto corresponding battery cells 105.

(67) In FIG. 8, the contact portion 112 can be elastically held in place by two spiral arms 114. The spiral arms can be the fusing element and can have a narrowed portion at a specific location to ensure when it melts, it melts at a certain spot along the spiral arm 114. In one embodiment, this can be located closer to the cell interconnect 102 and further away from the contact portion 112. The spiral arms 114 can essentially from a tension spring with a springy property that biases the contact portion 112 in an upward direction as shown in FIG. 8. During assembling of the brick 1 of battery cells 105, the contact portion 112 can be displaced downward towards the battery cells 105 and then welded onto the battery cells 105. The spiral arms 114 can retain its springy property or may be shape memory such that when the spiral arms 114 melts at any spot along its length, the remaining unmelt portion of the spiral arm 114 that is still connected to the cell interconnect 102 would spring upwards and away from the battery cell 105, thereby minimizing the chance of arcing between the remaining unmelt portion and the battery cell 105.

(68) The low-voltage fuse shown in FIG. 9 is similar to the one shown in FIG. 8 except here, the spiral arms 114 are encapsulated in silicone 107. The fuse element is encapsulated with silicone or any other suitable encapsulant. This encapsulant will degrade and draw energy 15 from an existing arc and help to isolate arc from metal parts in close vicinity.

(69) Further, the encapsulant can increase the voltage of a particular low-voltage fuse 110 for clearing the arc and could eliminate a need to have a cartridge certified HV fuse 120 altogether. Therefore, one particular embodiment of this disclosure includes a fusing system using only low-voltage fuses 110 such as those shown in FIGS. 9 and 13, and no high-voltage fuse 120 is used.

(70) Referring now to FIG. 10, which illustrates a design of the metal layer embedded within the cell interconnect 101, 102. As briefly discussed above, the metal layer of cell interconnect 102 of FIG. 2 can be similar to this in that an electronically isolated patch 109 of metal can be provided to ensure that one single battery cell 105 is in parallel with the rest of the battery cell 105 and is electronically protected by a high-voltage fuse 120. FIG. 11 is simply the underside of the metal layer of FIG. 10.

(71) Besides a double spiral 114 design for the fuse element, a low-voltage fuse 210 can have a straight fuse element 214 with a narrowed portion disposed or embedded between the layers of cell interconnect 102. In FIG. 12, the fuse element 214 can be centered in the interstitial space away from the gap 217. In this way, polluted air from the melt fuse element 214 is less likely to affect the battery cells 105 underneath the contact portion 212.

(72) In another embodiment, the straight fuse element of FIG. 12 can be encapsulated by an encapsulant 215, such as silicone (see FIG. 13). This can increase the voltage for clearing the arc and could eliminate a need for a cartridge certified HV fuse.

(73) The specification has set out a number of specific exemplary embodiments, but those skilled in the art will understand that variations in these embodiments will naturally occur in the course of embodying the subject matter of the disclosure in specific implementations and environments. It will further be understood that such variation and others as well, fall within the scope of the disclosure. Neither those possible variations nor the specific examples set above are set out to limit the scope of the disclosure. Rather, the scope of the present disclosure is defined solely by the claims set out below.

(74) Thus, specific embodiments and applications of high-voltage battery module parallel cell fusing system have been disclosed. It should be apparent, however, to those skilled in the art that many more modifications besides those already described are possible without departing from the disclosed concepts herein. The disclosed embodiments, therefore, is not to be restricted except in the spirit of the appended claims. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Insubstantial changes from the claimed subject matter as viewed by a person with ordinary skill in the art, now known or later devised, are expressly contemplated as being equivalent within the scope of the claims. Therefore, obvious substitutions now or later known to one with ordinary skill in the art are defined to be within the scope of the defined elements. The claims are thus to be understood to include what is specifically illustrated and described above, what is conceptually equivalent, what can be obviously substituted and also what essentially incorporates the essential idea of the embodiments. In addition, where the specification and claims refer to at least one of something selected from the group consisting of A, B, C . . . and N, the text should be interpreted as requiring at least one element from the group which includes N, not A plus N, or B plus N, etc.