Battery module

Abstract

The present disclosure relates to a battery module. A battery module comprises a battery cell array including a plurality of battery cells, a first connection member electrically connecting the first terminals of the plurality of battery cells to each other and connected to an external device through a first common node, and a second connection member electrically connecting the second terminals of the plurality of battery cells to each other and connected to an external device through a second common node, wherein the first common node is located adjacent to the first battery cell among the first and second battery cells located at the outermost edge of the battery cell array, and the second common node is located adjacent to the second battery cell among the first and second battery cells, and the first connection member is configured such that the resistance value per unit length gradually increases as it moves away from the first common node, and the second connection member is configured such that the resistance value per unit length gradually increases as it moves away from the second common node.

Description

Technology Field

[0001] The present disclosure relates to a battery module. Background Technology

[0002] Secondary batteries differ from primary batteries, which provide only the irreversible conversion of chemical substances into electrical energy, in that they can be repeatedly charged and discharged. Low-capacity secondary batteries are used as power sources for small electronic devices such as mobile phones, laptop computers, and camcorders, while high-capacity secondary batteries are used as power sources for electric vehicles.

[0003] Electric vehicles require the use of high-capacity batteries to increase driving range. Therefore, battery modules composed of multiple battery cells connected in series or parallel are used in electric vehicles. In particular, to construct a high-capacity battery module, a method of connecting multiple battery cells in parallel is used. The problem to be solved

[0004] The problem to be solved through the embodiments is to provide a battery module capable of uniform charging and discharging of battery cells by eliminating current deviations between battery cells connected in parallel. means of solving the problem

[0005] A battery module according to an embodiment for solving the above problem comprises a battery cell array including a plurality of battery cells, a first connection member electrically connecting the first terminals of the plurality of battery cells to each other and connected to an external device through a first common node, and a second connection member electrically connecting the second terminals of the plurality of battery cells to each other and connected to an external device through a second common node, wherein the first common node is located adjacent to the first battery cell among the first and second battery cells located at the outermost edge of the battery cell array, and the second common node is located adjacent to the second battery cell among the first and second battery cells, and the first connection member is configured such that the resistance value per unit length gradually increases as it moves away from the first common node, and the second connection member is configured such that the resistance value per unit length gradually increases as it moves away from the second common node.

[0006] The first connection member includes a plurality of first connection resistors sequentially connected along the arrangement direction of the plurality of battery cells, each of the plurality of first connection resistors connects the first terminals of two adjacent battery cells, and the plurality of first connection resistors may be configured such that the resistance value gradually increases as they move further away from the first common node.

[0007] The second connection member includes a plurality of second connection resistors sequentially connected along the arrangement direction of the plurality of battery cells, each of the plurality of second connection resistors connects the second terminals of two adjacent battery cells, and the plurality of second connection resistors may be configured such that the resistance value gradually increases as they move further away from the second common node.

[0008] The resistance values ​​of the plurality of first connection resistors and the plurality of second connection resistors can be determined to satisfy Equation 14.

[0009] [Equation 14]

[0010] R Bk = ((nk) / k)R Tk

[0011] The above n is the number of the plurality of battery cells, and the R Tk represents the first connection resistor located at the k-th position in the first direction away from the first common node among the plurality of first connection resistors, and R Bk represents the second connection resistor located at the k-th position in the first direction among the plurality of second connection resistors above.

[0012] The first connecting member is formed such that its width, thickness, or cross-sectional area gradually increases as it moves away from the first common node, thereby increasing the resistance value per unit length as it moves away from the first common node, and the second connecting member is formed such that its width, thickness, or cross-sectional area gradually increases as it moves away from the second common node, thereby increasing the resistance value per unit length as it moves away from the second common node.

[0013] The first and second connecting members above can be configured as a bus bar. Effects of the invention

[0014] According to the embodiments, current deviations between battery cells connected in parallel can be eliminated so that the battery cells can be charged and discharged uniformly. Brief explanation of the drawing

[0015] FIG. 1 schematically illustrates a battery module according to one embodiment. FIG. 2 illustrates an equivalent circuit of a battery module according to one embodiment. FIG. 3 is a diagram illustrating the effect of eliminating current deviation in a battery module according to one embodiment. Specific details for implementing the invention

[0016] Embodiments of the present invention will be described in detail below with reference to the attached drawings. The effects and features of the embodiments and the methods of implementation thereof will be described in detail below with reference to the attached drawings. In the drawings, the same reference numerals denote the same components, and redundant descriptions thereof are omitted. However, the present invention may be implemented in various forms and should not be interpreted as being limited to the embodiments described herein. Rather, these embodiments are provided as examples to ensure that the present disclosure is thorough and complete, and will sufficiently convey the aspects and features of the present invention to a person skilled in the art.

[0017] In this document, the term "and / or" includes any combination or any combination of the multiple items listed in relation to it. When describing embodiments of the present invention, the use of "may" or "may be" means "one or more embodiments of the present invention." In the following description of embodiments of the present invention, terms in the singular form may include the plural form unless otherwise specified in the context.

[0018] In this document, terms including ordinal numbers such as "first," "second," and "third" are used to describe various components, but these components are not limited by these terms. These terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the second component may be named the first component, and similarly, the first component may be named the second component.

[0019] Additionally, the size and thickness of each component shown in the drawings are arbitrarily depicted for convenience of explanation, and the embodiments are not necessarily limited to those illustrated. Thickness and area may be exaggerated in the drawings to clearly represent multiple layers and areas.

[0020] Where in this document one component or layer is described as being "on," "connected," or "combined" with respect to another component or layer, "on," "connected," and "combined" include both being formed directly or through one or more other components or layers. Furthermore, where one component or layer is described as being "between" two components or layers, it should be understood that it is the sole component or layer between the two components or layers, or that one or more interposed elements or layers exist. Additionally, electrically connecting two components includes not only directly connecting the two components but also connecting them through another component. Other components may include switches, resistors, capacitors, etc. In describing the embodiments, the expression "connected" means electrically connecting unless the expression "directly connected" is used.

[0022] FIG. 1 schematically illustrates a battery module according to one embodiment.

[0023] Referring to FIG. 1, the battery module (10) may include a battery cell array (11) and first and second connecting members (12, 13).

[0024] The battery cell array (11) may include a plurality of battery cells (C1 to C5) arranged sequentially along a predetermined direction (e.g., the x-direction in FIG. 1). FIG. 1 illustrates, for convenience of explanation, a case in which the battery cell array (11) includes five battery cells. However, the embodiments are not limited by this, so the number of battery cells included in the battery cell array (11) may be greater or less.

[0025] The first connecting member (12) is coupled to the positive terminals of a plurality of battery cells (C1 to C5) to electrically connect the positive terminals of the plurality of battery cells (C1 to C5) to each other. The second connecting member (13) is coupled to the negative terminals of a plurality of battery cells (C1 to C5) to electrically connect the negative terminals of the plurality of battery cells (C1 to C5) to each other. Accordingly, the plurality of battery cells (C1 to C5) can be connected in parallel between the first connecting member (12) and the second connecting member (13).

[0026] The first and second connecting members (12, 13) may be composed of conductive members such as bus bars.

[0027] The first and second connection members (12, 13) may each include a first common node (N1) and a second common node (N2). The first and second common nodes (N1, N2) may be electrically connected to an external device (e.g., a charger or a load). That is, the first and second common nodes (N1, N2) serve as current inlet / outlet ports for the first and second connection members (12, 13), respectively, and current flow between the first and second connection members (12, 13) and the external device may be made through the first and second common nodes (N1, N2).

[0028] The first and second common nodes (N1, N2) may be located in opposite directions relative to the center of the battery cell array (11). The first common node (N1) may be located adjacent to battery cell (C1) among the two battery cells (C1, C5) located at the outermost edge of the battery cell array (11), and the second common node (N2) may be located adjacent to battery cell (C5) among the two outermost battery cells (C12, C5). In this document, the center of the battery cell array (11) may refer to the center in the arrangement direction (x direction in FIG. 1) of the battery cells (C1 to C5) constituting the battery cell array (11).

[0029] The first connecting member (12) may be configured such that the resistance value per unit length gradually increases as it moves away from the first common node (N1) and gradually decreases as it moves closer to the first common node (N1). The second connecting member (13) may be configured such that the resistance value per unit length gradually increases as it moves away from the second common node (N2) and gradually decreases as it moves closer to the second common node (N2). In FIG. 1, the length direction of the first and second connecting members (12, 13) corresponds to the arrangement direction (x direction) of the battery cells (C1 to C5).

[0030] As illustrated in FIG. 1, the first connecting member (12) is formed such that its width gradually increases as it moves away from the first common node (N1), so that the resistance value per unit length can gradually increase as it moves away from the first common node (N1). Additionally, the second connecting member (13) is formed such that its width gradually increases as it moves away from the second common node (N2), so that the resistance value per unit length can gradually increase as it moves away from the second common node (N2).

[0031] FIG. 1 illustrates an example in which the width of the first and second connecting members (12, 13) is gradually increased / decreased to gradually increase / decrease the resistance value per unit length of the first and second connecting members (12, 13), but the embodiments are not limited thereto. In other embodiments, the height, cross-sectional area, etc. of the first and second connecting members (12, 13) may be gradually increased / decreased to gradually increase / decrease the resistance value per unit length of the first and second connecting members (12, 13).

[0032] Below, with reference to FIG. 2, a method for determining resistance values ​​according to the positions of the first connecting member (12) and the second connecting member (13) is described in detail.

[0033] FIG. 2 illustrates a schematic equivalent circuit of the battery module of FIG. 1. FIG. 2 shows V to the battery cell array (11) through the first and second common nodes (N1, N2). T Illustrates the case where a common voltage is applied.

[0034] In FIG. 2, the currents flowing through the battery cells (C1 to C5) are i1, i2, i3, i4, and i5, respectively, and The open-circuit voltage of the battery cells (C1 ~ C5) is V, respectively. oc1 , V oc2 , V oc3 , V oc4 , and V oc5 And the internal resistances of the battery cells (C1 to C5) are Z1, Z2, Z3, Z4, and Z5, respectively.

[0035] Referring to FIG. 2, the first connecting member (12) comprises a plurality of first connecting resistors (R) sequentially connected in series along the arrangement direction of the battery cells (C1 to C5) (refer to the x-direction in FIG. 1). T1 ~ R T4 It may include a plurality of first connection resistors (R T1 ~ R T4 Each ) can electrically connect the positive terminals of two adjacent battery cells to each other. The second connecting member (13) comprises a plurality of second connecting resistors (R) sequentially connected in series along the arrangement direction (x direction) of the battery cells (C1 to C5). B1 ~ R B4 It may include a plurality of second connection resistors (R B1 ~ R B4 Each ) can electrically connect the negative terminals of two adjacent battery cells to each other.

[0036] R T1 is a connecting resistor that connects the positive terminals of the first and second battery cells (C1, C2) to each other, and R B1R is a connecting resistor that connects the negative terminals of the first and second battery cells (C1, C2) to each other. T2 is a connecting resistor that connects the positive terminals of the second and third battery cells (C2, C3) to each other, and R B2 R is a connecting resistor that connects the negative terminals of the second and third battery cells (C2, C3) to each other. T3 is a connecting resistor that connects the positive terminals of the third and fourth battery cells (C3, C4) to each other, and R B3 R is a connecting resistor that connects the negative terminals of the third and fourth battery cells (C3, C4) to each other. T4 is a connecting resistor that connects the positive terminals of the 4th and 5th battery cells (C4, C5) to each other, and R B4 is a connecting resistor that connects the negative terminals of the 4th and 5th battery cells (C4, C5) to each other.

[0037] Multiple first connection resistors (R T1 ~ R T4 ) can be configured so that the resistance value gradually increases along the arrangement direction (x direction) of the battery cells (C1 ~ C5). That is, a plurality of first connection resistors (R T1 ~ R T4 ) can be configured such that the resistance value gradually increases as it moves away from the first common node (N1) and gradually decreases as it approaches the first common node (N1). A plurality of second connection resistors (R B1 ~ R B4 ) can be configured so that the resistance value gradually decreases along the arrangement direction (x direction) of the battery cells (C1 ~ C5). That is, a plurality of second connection resistors (R B1 ~ R B4 ) can be configured so that the resistance value gradually decreases as it gets closer to the second common node (N2) and gradually increases as it gets further away from the second common node (N2).

[0038] First and second connecting resistors (R T1 ~ R T4 , RB1 ~ R B4 As explained with reference to FIG. 1, the resistance value can be adjusted by adjusting the physical shape of the corresponding connecting member (12, 13).

[0039] Below, referring to the necessary formulas, the first and second connecting resistors (R) according to their positions T1 ~ R T4 , R B1 ~ R B4 Explain in detail how to determine the resistance value of ).

[0040] Battery cells (C1 ~ C5) have identical characteristics (Z1=Z2=Z3=Z4=Z5, V oc1 =V oc2 =V oc3 =V oc4 =V oc4 Assuming it has ), the common voltage (V T ) can be expressed by the following mathematical formulas 1 to 5.

[0041] [Formula 1]

[0042] V T = i1Z1+ V oc1 + i1R B1 + (i1+i2)R B2 + (i1+i2+i3)R B3 + (i1+i2+i3+i4)R B4

[0043] [Mathematical Formula 2]

[0044] V T = i2Z2+ V oc2 + (i2+i3+i4+i5)R T1 + (i1+i2)R B2 + (i1+i2+i3)R B3 + (i1+i2+i3+i4)R B4

[0045] [Equation 3]

[0046] V T = i3Z3+ V oc3 + (i2+i3+i4+i5)R T1 + (i3+i4+i5)RT2 + (i1+i2+i3)R B3 + (i1+i2+i3+i4)R B4

[0047] [Equation 4]

[0048] V T = i4Z4+ V oc4 + (i2+i3+i4+i5)R T1 + (i3+i4+i5)R T2 + (i4+i5)R T3 + (i1+i2+i3+i4)R B4

[0049] [Formula 5]

[0050] V T = i5Z5+ V oc5 + (i2+i3+i4+i5)R T1 + (i3+i4+i5)R T2 + (i4+i5)R T3 + i5R T4

[0051] Assuming that the same current flows through all battery cells (C1 to C5), subtracting Equation 1 from Equation 2 above results in the following Equation 6.

[0052] [Equation 6]

[0053] (i2Z2+ V oc2 + (i2+i3+i4+i5)R T1 + (i1+i2)R B2 + (i1+i2+i3)R B3 + (i1+i2+i3+i4)R B4 ) - (i1Z1+ V oc1 + i1R B1 + (i1+i2)R B2 + (i1+i2+i3)R B3 + (i1+i2+i3+i4)R B4 ) = i1R B1 - (i2+i3+i4+i5)R T1 = 0

[0054] From Equation 6 above, the two connecting resistors (R B1 , R T1The relationship between ) can be derived as the following Equation 7.

[0055] [Equation 7]

[0056] R B1 = ((i2+i3+i4+i5) / i1)R T1 = 4R T1

[0057] In addition, if Equation 2 is subtracted from Equation 3 above, it can be expressed as the following Equation 8.

[0058] [Equation 8]

[0059] (i3Z3+ V oc3 + (i2+i3+i4+i5)R T1 + (i3+i4+i5)R T2 + (i1+i2+i3)R B3 + (i1+i2+i3+i4)R B4 ) - (i2Z2+ V oc2 + (i2+i3+i4+i5)R T1 + (i1+i2)R B2 + (i1+i2+i3)R B3 + (i1+i2+i3+i4)R B4 ) = (i3+i4+i5)R T2 - (i1+i2)R B2

[0060] [Formula 9]

[0061] From Equation 8 above, the two connecting resistors (R B2 , R T2 The relationship between ) can be derived as the following Equation 9.

[0062] R B2 = ((i3+i4+i5) / (i1+i2))R T2 = (3 / 2)R T2

[0063] In addition, if Equation 3 is subtracted from Equation 4 above, it can be expressed as the following Equation 10.

[0064] [Formula 10]

[0065] (i4Z4+ V oc4 + (i2+i3+i4+i5)RT1 + (i3+i4+i5)R T2 + (i4+i5)R T3 + (i1+i2+i3+i4)R B4 ) - (i3Z3+ V oc3 + (i2+i3+i4+i5)R T1 + (i3+i4+i5)R T2 + (i1+i2+i3)R B3 + (i1+i2+i3+i4)R B4 ) = ((i4+i5)R T3 ) - ((i1+i2+i3)R B3 )

[0066] [Equation 11]

[0067] From Equation 10 above, the two connecting resistors (R B3 , R T3 The relationship between ) can be derived as the following Equation 9.

[0068] R B3 = ((i4+i5) / (i1+i2+i3))R T3 = (2 / 3)R T3

[0069] In addition, if Equation 4 is subtracted from Equation 5 above, it can be expressed as the following Equation 12.

[0070] [Equation 12]

[0071] (i5Z5+ V oc5 + (i2+i3+i4+i5)R T1 + (i3+i4+i5)R T2 + (i4+i5)R T3 + i5R T4 ) - (i4Z4+ V oc4 + (i2+i3+i4+i5)R T1 + (i3+i4+i5)R T2 + (i4+i5)R T3 + (i1+i2+i3+i4)R B4 ) = (i5R T4 ) - ((i1+i2+i3+i4)R B4 )

[0072] [Equation 13]

[0073] From Equation 12 above, the two connecting resistors (R B4 , R T4 The relationship between ) can be derived as the following Equation 9.

[0074] R B4 = (i5 / (i1+i2+i3+i4))R T3 = (1 / 4)R T4

[0075] The above formula 7(R B1 = 4R T1 , Formula 9(R B2 = (3 / 2)R T2 ), Formula 11(R B3 = (2 / 3)R T3 ), and Formula 13(R B4 = (1 / 4)R T4 Generalizing ) can be expressed as the following Equation 14.

[0076] [Equation 14]

[0077] R Bk = ((nk) / k)R Tk

[0078] In the above formula 14, n is the number of battery cells (C1 to C5) constituting the battery cell array (11), and R Tk is a plurality of first connection resistors (R) constituting the first connection member (12). T1 ~ R T4 The k-th first connection resistance can be represented based on the arrangement direction (x-direction in FIG. 1) of the battery cells (C1 ~ C5) among ). In addition, R Bk is a plurality of second connection resistors (R) constituting the second connection member (13). B1 ~ R B4 The k-th second connection resistance can be represented based on the arrangement direction (x direction in Fig. 1) of the battery cells (C1 to C5).

[0079] In the embodiment, the first and second connecting resistors (R) satisfy Equation 14 above. T1 ~ R T4 , RB1 ~ R B4 The resistance value of ) can be determined. In addition, the first and second connecting resistors (R T1 ~ R T4 , R B1 ~ R B4 Based on the resistance value of ), the shape of the first and second connecting members (12, 13) can be adjusted.

[0080] FIG. 3 is a diagram illustrating the effect of eliminating current deviation in a battery module according to one embodiment.

[0081] In FIG. 3, the comparison example is the first and second connecting resistors (R T1 ~ R T4 , R B1 ~ R B4 Configure all resistance values ​​of ) to be the same (R T1 = R T2 = R T3 = R T4 = R B1 = R B2 = R B3 = R B4 This is the result of simulating the charge / discharge amount (Ah) of each battery cell (C1 ~ C5) by setting = 1.0mΩ). In addition, the embodiment satisfies the above mathematical formula 14 by configuring the first and second connecting resistors (R T1 ~ R T4 , R B1 ~ R B4 Configure the resistance value of (R T1 = 0.4mΩ, R T2 = 0.8mΩ, R T3 = 1.2mΩ, R T4 = 1.6mΩ, R B1 = 1.6mΩ, R B2 = 1.2mΩ, R B3 = 0.8mΩ, R B4 This is the result of simulating the charge / discharge amount (Ah) of each battery cell (C1 ~ C5) by (= 0.4mΩ). The comparison example and embodiment in Fig. 3 are the results of simulating charge / discharge with the same current and voltage for the same amount of time.

[0082] Table 1 below is a table of the graph in Figure 3, where (max-min) represents the value obtained by subtracting the charge / discharge amount (min) of the battery cell with the smallest charge / discharge amount from the charge / discharge amount (max) of the battery cell with the largest charge / discharge amount.

[0083] C1 C2 C3 C4 C5 (Max-min) Comparison Example 1.751 1.723 1.714 1.723 1.751 0.04 Example of implementation 1.739 1.739 1.739 1.739 1.739 0

[0084] Referring to FIG. 3 and FIG. 1, the first and second connecting resistors (R T1 ~ R T4 , R B1 ~ R B4 If the resistance values ​​of ) are all configured to be the same, a deviation in the charge / discharge amount occurs due to the current deviation of the battery cells (C1 ~ C5). On the other hand, as in the aforementioned embodiment, the first and second connecting resistors (R) to satisfy Equation 14 above T1 ~ R T4 , R B1 ~ R B4 When the resistance value of ) is configured, the current deviation of the battery cells (C1 to C5) is eliminated, and accordingly, the charge and discharge amounts of all battery cells (C1, C2, C3) can be made equal. The above-described embodiment can increase the maximum allowable current of the battery module by eliminating the current deviation between the battery cells in this way. Furthermore, not only the temperature deviation between battery cells caused by the current deviation, but also the lifespan deviation between battery cells caused by the current and temperature deviations can be reduced.

[0086] The electronic or electrical devices and / or any other related devices or components according to the embodiments of the present invention described herein may be implemented using any suitable hardware, firmware (e.g., application-specific integrated circuit), software, or a combination of software, firmware, and hardware. For example, various components of these devices may be formed on a single integrated circuit (IC) chip or on individual IC chips. Additionally, various components of these devices may be implemented on a flexible printed circuit film, a tape carrier package (TCP), a printed circuit board (PCB), or a substrate. The electrical connections or interconnections described herein may be implemented, for example, by wiring or conductive elements on a PCB or other type of circuit carrier. Conductive elements may include metallizations, such as surface metallizations, and / or pins, and may include conductive polymers or ceramics. In addition, electrical energy can be transmitted, for example, through wireless access using electromagnetic radiation or light.

[0087] In addition, various components of these devices may be processes or threads that execute on one or more processors and within one or more computing devices to perform the various functions described herein, execute computer program instructions, and interact with other system components. Computer program instructions are stored in memory that may be implemented in computing devices using standard memory devices, such as, for example, random access memory (RAM). Computer program instructions may also be stored in other non-transitory computer-readable media, such as, for example, CD-ROMs and flash drives.

[0088] In addition, those skilled in the art should recognize that the functions of various computing devices may be combined or integrated into a single computing device, or that the functions of a specific computing device may be distributed across one or more other computing devices without departing from the scope of the exemplary embodiments of the present invention. Explanation of the symbols

[0089] 10: Battery module 11: Battery cell array 12: First connecting member 13: Second connection missing C1 ~ C5: Battery cells N1: 1st common node N2: 2nd common node R T1 ~ R T4 : First connecting resistor R B1 ~ R B4 : Second connecting resistor

Claims

Claim 1 A battery cell array comprising a plurality of battery cells, a first connection member electrically connecting first terminals of the plurality of battery cells to each other and connected to an external device through a first common node, and a second connection member electrically connecting second terminals of the plurality of battery cells to each other and connected to an external device through a second common node, wherein the first common node is located adjacent to the first battery cell among the first and second battery cells located at the outermost edge of the battery cell array, and the second common node is located adjacent to the second battery cell among the first and second battery cells, wherein the first connection member is configured such that the resistance value per unit length gradually increases as it moves away from the first common node, and the second connection member is configured such that the resistance value per unit length gradually increases as it moves away from the second common node, wherein the first connection member includes a plurality of first connection resistors that are sequentially connected along the arrangement direction of the plurality of battery cells and electrically connect the first terminals of two adjacent battery cells to each other, and the second connection member is configured such that the arrangement direction of the plurality of battery cells A battery module comprising a plurality of second connection resistors that are sequentially connected and electrically connect the second terminals of two adjacent battery cells, wherein the resistance values ​​of the plurality of first connection resistors and the plurality of second connection resistors are determined to satisfy Equation 14. [Equation 14] RBk = ((nk) / k)RTk, wherein n is the number of the plurality of battery cells, RTk represents the first connection resistor located at the k-th position in the first direction away from the first common node among the plurality of first connection resistors, and RBk represents the second connection resistor located at the k-th position in the first direction among the plurality of second connection resistors. Claim 2 A battery module according to claim 1, wherein the plurality of first connection resistors are configured such that the resistance value gradually increases as they move further away from the first common node. Claim 3 A battery module according to paragraph 2, wherein the plurality of second connection resistors are configured such that the resistance value gradually increases as they move further away from the second common node. Claim 4 delete Claim 5 delete Claim 6 In claim 1, the first and second connecting members are configured as a bus, forming a battery module.

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