Patent Application
20250030112
The present application claims priority to and the benefit of Korean Patent Application No. 10-2023-0094896, filed on Jul. 20, 2023, in the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference.
The present disclosure relates to a rechargeable battery pack.
Unlike primary batteries, rechargeable batteries are batteries that repeatedly charge and discharge. Small-capacity rechargeable batteries are used in small, portable electronic devices such as mobile phones, laptop computers, and camcorders. High-capacity and high-density secondary batteries are used as power sources for driving motors in hybrid and electric vehicles or for energy storage.
A rechargeable battery module may include a plurality of battery cells connected in series and/or parallel to drive a motor of, for example, a hybrid vehicle that requires relatively high energy density. For example, a rechargeable battery module may be formed by stacking a plurality of battery cells in a frame and the number of battery cells may depend on a desired amount of power of the rechargeable battery module (e.g., for an electric vehicle).
Such rechargeable battery modules are connected in series and/or parallel within a housing manufactured using various methods to form a rechargeable battery pack. Therefore, various types of rechargeable battery modules are being manufactured to suit the capacity of the rechargeable battery pack.
However, in terms of energy capacity, packs with rechargeable battery modules have limitations. Therefore, in order to maximize the energy of the rechargeable battery pack, it is desirable to manufacture a rechargeable battery pack that directly assembles the battery cells without a rechargeable battery module.
The above information disclosed in this Background section is for enhancement of understanding of the background of the present disclosure, and therefore, it may contain information that does not constitute prior art.
Embodiments of the present disclosure relates to a rechargeable battery pack that maximizes or at least increases pack energy density by stacking battery cells.
A rechargeable battery pack according to embodiments of the present disclosure includes a center frame supporting the cell stack with a first bottom and a first side wall, a first side frame and a second side frame coupled to the center frame in a second direction crossing the first direction and having a second bottom and a second side wall to support a cell narrow side of the cell stack, and a first end frame and a second end frame coupled to both ends of the center frame, the first side frame, and the second side frame in the first direction to support a cell wide side of the cell stack.
The rechargeable battery pack according to embodiments of the present disclosure may further include a cross center frame coupled to the center frame, the first side frame, and the second side frame in the middle of the first direction to support the cell wide sides of the different cell stacks on both sides of the first direction.
The center frame, the first side frame, and the second side frame may correspond to various sizes of the cell stack depending on the length in the first direction.
The cell stack may include insulating members provided at both ends of the first direction, and a pressurizing body disposed outside the insulating member at at least one side of both ends in the first direction.
The pressurizing body may include a first plane portion disposed on the cell stack side, a second plane portion formed integrally with the first plane portion to form a gap, and a compressing force generator supported on the end frame by screwing the second plane portion and causing the first plane portion to press the cell stack.
The first plane portion is formed with an area corresponding to the cell wide side of the cell stack, the second plane portion is formed to have a smaller area than the first plane portion, and the pressurizing body may further include an inclined surface portion connecting the first plane portion and the second plane portion in a direction inclined to the first direction.
The pressurizing body may further include a rib connecting the first plane portion and the second plane portion in the first direction.
The first plane portion and the second plane portion may have a a partially cut recess portion at a portion where the electrode terminals of the battery cell are disposed.
The first flat part may have a first vent hole, and the second plane portion may have second vent holes penetrating on both sides of the compressing force generator and connected to the first vent hole.
The rechargeable battery pack may further include a pack cover mounted on the first side frame, the second side frame, and the first end frame and the second end frame, wherein at least one of the first end frame and the second end frame has a pack vent connected to the second vent hole.
The first side frame and the second side frame may have an adhesive injection port provided at the top of the third direction, an inclined portion connected to the adhesive injection port and inclined inward in the second direction, and an inductive gap portion connected to the inclined portion to form a gap that guides adhesive to the cell narrow side and a cell bottom of the battery cell. The inductive gap may be filled with an adhesive.
The rechargeable battery pack of embodiments of the present disclosure may be provided between the second side wall and the cell stack and may further include insulation having a length (L) and a height (H) on the side and bottom surfaces of the cell stack.
The first side frame and the second side frame may have the adhesive injection port, the inclined portion, and the inductive gap portion on at least one side in the second direction.
The center frame may include an adhesive injection port provided at the top of the third direction, a first inclined portion and a second inclined portion connected to the adhesive injection port and inclined respectively inward and outward in the second direction, and a first inductive gap portion and a second inductive gap portion respectively connected to the first inclined portion and the second inclined portion and respectively induce the adhesive to the cell narrow side of the battery cell disposed on both sides in the second direction. The first inductive gap portion and the second inductive gap portion may be filled with an adhesive.
The rechargeable battery pack according to embodiments of the present disclosure may be provided between the inner side of the side wall in the second direction and the cell stack and between the outer side of the side wall in the second direction and the cell stack, and may further include a first insulation and a second insulation having a length (L) and a height (H) on the side and bottom surfaces of the cell stack.
The first side frame and the second side frame may have the adhesive injection port, the first inclined portion and the second inclined portion, and the first inductive gap portion and the second inductive gap portion on at least one side in the second direction.
The first side frame and the second side frame may include a flange that is formed to be long along the first direction at the outer edge of the second direction and is mounted on a vehicle.
The first bottom and the second bottom may form refrigerant passages, and the refrigerant passages may be connected to each other at both ends in the first direction, and may be connected to a refrigerant inlet and a refrigerant outlet provided at both ends of the second direction at one end of the first direction.
The rechargeable battery pack of embodiments is equipped with a cell stack that stacks a plurality of battery cells in a first direction with a center frame, first and second side frames, and first and second end frames, so that pack energy density may be maximized or at least increased.
According to embodiments, the center frame, first and second side frames may correspond to various sizes of the cell stack depending on the length in the first direction. Additionally, because embodiments include a pressurizing body in the cell stack, the cell stack may be pressed in the first direction.
Hereinafter, the present invention will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. The drawings and description are to be regarded as illustrative in nature and not restrictive. Like reference numerals designate like elements throughout the specification.
Referring to
In an embodiment in which the pack frame 200 is configured to extend lengthwise in the first direction (x-axis direction), the pack frame 200 may further include a lateral or cross center frame 40. The lateral center frame 40 is coupled to the center frame 10 and the first and second side frames 21 and 22 in an intermediate portion (e.g., the middle or substantially the middle) of the center frame 10 in the first direction (x-axis direction) to support the different cell stacks 100 on both sides of the lateral center frame 10 in the first direction (x-axis direction).
The sizes (lengths) of the center frame 10 and the first and second side frames 21 and 22 may correspond to the size (length) of the cell stack 100 in the first direction (x-axis direction). That is, the center frame 10 and the first and second side frames 21 and 22 may be cut to an appropriate length depending on the length of the cell stack 100 in the first direction (x-axis direction).
In the pack frame 200, the center frame 10, the first side frame 21, and the second side frame 22 form an assembly space for the cell stack 100.
The cross-sectional shape and the length of the center frame 10, and the first and second side frames 21 and 22 may be selected depending on the various energy requirements of electric vehicles that utilize the cell stacks 100.
The center frame 10 includes a first bottom 11 and a first side wall 12 configured to support the cell stack 100. The first side wall 12 has a height extending upward in the third direction (z-axis direction) from the center (or substantially the center) of the first bottom 11 in the second direction (y-axis direction) and extends lengthwise in the first direction (x-axis direction). Accordingly, the center frame 10 is formed at both sides in the second direction (y-axis direction) with an open first bottom 11 without side walls.
The first side frame 21 and the second side frame 22 are each coupled to the center frame 10 in the second direction (y-axis direction) crossing the first direction (x-axis direction), and each have a second bottom 211 and second side walls 212 and 213 to support a cell narrow side (xz plane) of the cell stacks 100.
The first end frame 31 and the second end frame 32 are coupled to both ends (i.e., opposite ends) of the center frame 10 and the first and second side frames 21 and 22 in the first direction (x-axis direction) to support a cell wide side (yz plane) of the cell stacks 100.
Before being mounted on the pack frame 200, the cell stack 100 is in an uncompressed state. Each of the battery cells 101 is a square rechargeable battery, has the wide cell side (yz plane) and the narrow cell side (xz plane), and includes electrode terminals 102 and 103 at the top.
In the battery cell 101, the cell wide side (yz plane) faces both sides of the first direction (x-axis direction). The cell narrow side (xz plane) faces both sides of the second direction (y-axis direction) orthogonal to the first direction (x-axis direction). The electrode terminals 102 and 103 face upward in the third direction (z-axis direction) orthogonal to the first and second directions (x- and y-axis directions).
Referring to
Referring to
The compressing force generator 53 is supported on the end frame 32 by screwing the compressing force generator 53 into the second plane portion 52 so that the first plane portion 51 presses the cell stack 100. In one or more embodiments, the compressing force generator 53 is a bolt.
The bolt head of the compressing force generator 53 is between the first and second plane portions 51 and 52 and is rotationally adjustable. The end of the compressing force generator 53 that is screwed into the second plane portion 52 is supported on the end frame 32. As the amount of protrusion of the end of the compressing force generator 53 toward the second plane portion 52 increases, the first plane portion 51 applies more compressing force to the cell stack 100.
In one or more embodiments, the cell stack assembly space is larger than the dimensions of the cell stack 100, and the cell stack 100 is assembled in the cell stack assembly space in an uncompressed state. The pressurizing body 50 configured to compress the cell stack 100 is located on at least one side of the cell stack 100 in the first direction.
In response to the compressing force generator 53 being rotated, the pressurizing body 50 moves in a direction opposite to that of the compressing force generator 53 and compresses the cell stack 100. Compressing the cell stack 100 adjusts the overall dimensions of the cell stack 100 in the first direction and enables welding a bus bar 104 (see
Compressing the cell stack 100 is performed by rotating the compressing force generator 53 of the pressurizing body 50 after the cell stack 100 is assembled to the pack frame 200. After assembly and compressing all cell stacks 100 are completed, the bus bars 104 are laser welded to the electrode terminals 102 and 103 of the battery cells 101.
In an event in which a laser welding defect occurs, the compressing force generator 53 of the defective cell stack 100 may be released so that only the corresponding cell stack 100 may be reworked (e.g., the laser welding may be reperformed). Accordingly, the rechargeable battery pack of embodiments allows the cell stack 100 to be reworked when a defect occurs during the process.
Rotating the compressing force generator 53 causes the pressurizing body 50 to compress the battery cells 100. The compressing force may be adjusted in various ways by adjusting the bolt exterior diameter, material, and torque value of the compressing force generator 53.
The relationship between the torque applied to the compressing force generator 53 (e.g., the bolt), and the axial force of the compressing force generator 53 may be calculated as shown in Equation 1.
In Equation 1, F is the axial bolt force (compressing force) (N), T is the wrench torque (Nm), K is a constant that varies depending on the material and size, d is the nominal bolt diameter (m), and L is the lubrication coefficient (%).
In an embodiment in which T=10 Nm, K=0.2 (zink plated), d=0.02 m (Ø20 mm), and L=0%, the compressing force is approximately 2500N. The compressing force may be applied to the cell stack 100 by applying various variable values of the compressing force generator (e.g., bolt).
In one or more embodiments, the position of the compressing force generator 53 with respect to the pressurizing body 50 may be specified. In the pressurizing body 50, the first plane portion 51 is formed with an area corresponding to 1 the cell wide side (yz plane) of the cell stack 100. In one or more embodiments, the second plane portion 52 has a smaller area than the first plane portion 51.
The pressurizing body 50 further includes an inclined surface portion 54 connecting the first plane portion 51 and the second plane portion 52 in a direction inclined with respect to the first direction (x-axis direction). The pressurizing body 50 further includes a rib 55 connecting the first plane portion 51 and the second plane portion 52 in the first direction (x-axis direction). The inclined surface portion 54 and the rib 55 strengthen the mechanical strength of the pressurizing body 50 and prevent (or at least mitigate) deformation when the compressing force is transmitted from the second plane portion 52 to the first plane portion 51.
In addition, the first plane portion 51 and the second plane portion 52 include recess portions 511 and 521 (e.g., notches), respectively, that are partially cut at the portion where the electrode terminals 102 and 103 of the battery cell 101 are located. The recess portions 511 and 521 prevent or at least reduce strong compressing forces from being applied to the electrode terminals 102 and 103, which are structurally more complex and vulnerable portions of the battery cell 101 than the portion including an electrode assembly (not shown).
In addition, the first plane portion 51 has a first vent hole 512, and the second plane portion 52 has second vent holes 522 on both sides of the compressing force generator 53 and connected to the first vent hole 512.
The position of the compressing force generator 53 is at the center (or approximately the center) of the first and second plane portions 51 and 52 of the pressurizing body 50 to apply a uniform (or approximately uniform) compressing force and does not protrude above the contact surface of the cell stack 100.
A compressible distance CL of the compressing force generator 53 is the distance between the lower end of the bolt head and the inner surface of the second plane portion 52. In one or more embodiments in which the maximum compression requirement is 7 mm, it may be designed as follows.
Wrench work is possible at a gap G2 set between the first and second flat portions 51 and 52 at the upper center portion of the pressurizing body 50. In order to prevent (or at least mitigate) stress from concentrating on the second plane portion 52 and to apply uniform (or approximately uniform) compressing force, the bolt diameter may be made as large as possible within a range that does not cause issues with assembly.
Once the assembly of the cell stack 100 on the pack frame 10 and the laser welding of the bus bar 104 are completed, additional fixation of the cell stack 100 may be performed. If the cell stack 100 is not completely fixed, the battery cell 101 may move during cell swelling, vibration, or impact, which may cause a fire or explosion. In one or more embodiments, after the cell stack 100 is assembled, side bonding is applied to both sides of the cell stack 100 in the second direction (x-axis direction).
The adhesive injection port 221 is provided at the top in the third direction (z-axis direction) to enable injection of adhesive. The inclined portion 222 is connected to the adhesive injection port 221 and is inclined inward in the second direction (y-axis direction). The inclined portion 222 is configured to allow the injected adhesive to flow downward.
The gap portion 223 is connected to the inclined portion 222 to form a gap that induces or guides the adhesive to flow downward from the cell narrow side (xz plane) of the battery cells 101 and the cell bottom (xy plane) of the battery cells 101. The gap portion 223 is filled with adhesive 224 at the cell bottom (xy plane) and the cell narrow side (xz plane) adjacent to the cell bottom.
The filled adhesive 224 has a length (L) set at the cell bottom (xy plane) and a height (H) set at the cell narrow side (xz plane). The adhesive 224 attaches the battery cells 101 of the cell stack 100 to the first and second side frames 21 and 22.
An L-shaped insulation 214 with a length (L) and height (H) may be applied to the side and bottom surfaces of the cell stack 100 to form a space for adhesive to flow between the cell stack 100 and the second side walls 212 and 213, and between the cell stack 100 and the second bottom 211.
In this manner, the cell stack 100 is prevented from being assembled eccentrically (i.e., crooked) between the second side walls 212 and 213, and a minimum space equal to the thickness of the insulation 214 may be achieved. The adhesive flows down and is absorbed into the insulation 214. In one or more embodiments, the adhesive has a viscosity capable of providing adhesion with the insulation 214.
The side bonding of the cell stack 100 may be achieved. An inclination angle θ of the inclined portion 222 for applying the adhesive may be adjusting depending on the viscosity of the adhesive. In one or more embodiments, the inclination angle θ may be larger for a relatively low-viscosity adhesive, and the inclination angle θ may be smaller for a relatively high-viscosity adhesive.
A gap GG between the battery cell 101 and the second side walls 212 and 213 for adhesive application may be adjusted depending on the viscosity of the adhesive, and may be adjusted by adjusting the length (L) and height (H) of the insulation 214. That is, the gap GG may be larger for a relatively high-viscosity adhesive, and the gap GG may be smaller for a relatively low-viscosity adhesive.
In one or more embodiments in which the adhesive has a viscosity of 5000 cps, the inclination angle θ may be in a range from approximately 40° to approximately 50°, and the gap GG may be in a range from approximately 1.0 mm to approximately 2.0 mm. In one or more embodiments, the inclination angle θ may be approximately 45° and the gap GG may be approximately 1.5 mm.
In an embodiment in which the adhesive has a viscosity of approximately 10000 cps, the inclination angle θ may be in a range from approximately 250 to approximately 35°, and the gap GG may be in a range from approximately 2.0 mm to approximately 3.0 mm. In one or more embodiments, the inclination angle θ may be approximately 30° and the gap GG may be approximately 2.5 mm.
The first and second side frames 21 and 22 may have the adhesive injection port 221, the inclined portion 222, and the inductive gap portion 223 on one of the second side walls 212 and 213 in the second direction (y-axis direction). In the illustrated embodiment, the adhesive injection port 221, the inclined portion 222, and the gap portion 223 may be provided on each of the second side walls 212 and 213 in the second direction (y-axis direction) to provide a stronger adhesion with the battery cells 101.
Referring to
Because the first side wall 12 of the center frame 10 corresponds to the second side wall 213 of the first and second side frames 21 and 22, a separate illustration of the first side wall 12 of the center frame 10 will be omitted, and will be described by the adhesive injection port 121, the first inclined portion 122 and the second inclined portion 123, and the first gap portion 124 and a second gap portion 125 provided in the second side wall 213 of the first and second side frames 21 and 22 of
The adhesive injection port 121 is provided at the top in the third direction (z-axis direction) to enable injection of adhesive. The first inclined portion 122 and the second inclined portion 123 are connected to the adhesive injection port 121 and are formed to be inclined inward and outward in the second direction, respectively.
The first gap portion 124 and the second gap portion 125 are connected to the first inclined portion 122 and the second inclined portion 123, respectively, and induce or guide the flow of the adhesive to each cell narrow side (xz plane) of the battery cells 101 on both sides of the first side wall 12 of the center frame 10 in the second direction. The first gap portion 124 and the second gap portion 125 are filled (or substantially filled) with the adhesive 224 at the cell bottom (xy plane) and the cell narrow side (xz plane) of the battery cells 101 adjacent to the cell bottom.
The first and second side frames 21 and 22 include the adhesive injection port 121, the first inclined portion 122 and the second inclined portion 123, and the first gap portion 124 and the second gap portion 125 on the second side wall 213.
In the first and second side frames 21 and 22, the first gap portion 124 and the second gap portion 125 are filled (or substantially filled) with the adhesive 224 at the cell bottom (xy plane) and the cell narrow side (xz plane) of the battery cells 101 adjacent to the cell bottom.
A first insulation 245 and a second insulation 246 are located between the inside of the side wall 12 and the cell stack 100 in the second direction and between the outside of the side wall 12 and the cell stack 100 in the second direction, respectively. The first insulation 245 and the second insulation 246 each have an L-shaped cross-section with the length (L) and the height (H) of the first and second insulations 245, 246 on the side and bottom surfaces of the cell stack 100 to provide a space for the adhesive to flow.
The pack cover 300 covers the bus bar 104 that electrically connects the electrode terminals 102 and 103 of the battery cells 101 together. In one or more embodiments, at least one of the first and second end frames 31 and 32 includes a pack vent 400 connected to a second vent hole 522.
The gap G1 between the busbar 104 and the pack cover 300 is connected to (in fluid communication with) the gap G2 set between the first plane portion 51 of the pressurizing body 50 and the first plane portion 51. These gaps G1 and G2, together with the recess portions 511 and 521 and the first and second vent holes 512 and 522, enable the discharge of gas generated from the battery cells 101 during an event. This gas may be safely discharged to the outside of the rechargeable battery pack through the pack vent 400 provided in the second end frame 32 via the third vent hole 322 in the second end frame 32.
Referring again to
In addition, the first bottom 11 of the center frame 10 and the second bottom 211 of each of the first and second side frames 21 and 22 form a plurality of refrigerant passages 60 (see
While this disclosure has been described in connection with what is presently considered to be practical embodiments, it is to be understood that the disclosure is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2023-0094896 | Jul 2023 | KR | national |
