Secondary battery module

Abstract

To provide a secondary battery module that can accommodate volumetric changes in unit cells, and apply an appropriate pressure to a unit cell or secondary battery module while limiting the maximum deformation of the module due to expansion of the unit cell.SOLUTION: A secondary battery module according to the present disclosure includes one or more cell stacks including a plurality of unit cells, at least one first compression pad disposed between the plurality of unit cells, and a pair of end plates disposed opposite each other outside the one or more cell stacks.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a secondary battery module for accommodating volumetric changes of unit cells. [Background technology]

[0002] A secondary battery is a battery that can be charged and discharged, unlike a primary battery that cannot be charged. Low-capacity secondary batteries are used in small portable electronic devices such as smartphones, feature phones, laptop computers, digital cameras, and camcorders, while large-capacity secondary batteries are widely used as motor drive power sources and power storage batteries in hybrid and electric vehicles. Such secondary batteries include an electrode assembly consisting of a positive electrode and a negative electrode, a case that houses the electrode assembly, and an electrode terminal connected to the electrode assembly.

[0003] A secondary battery cell has the characteristic of expanding and contracting depending on the external environment and the charge / discharge state. In addition, to ensure optimal performance and lifespan of a secondary battery, it is necessary to apply an appropriate pressure to the secondary battery cell. However, if a pressure higher than the appropriate pressure is applied to a secondary battery cell, cracks may occur in the electrode plates, reducing electrical conductivity and causing peeling or a decrease in capacity due to lithium plating. On the other hand, if a pressure lower than the appropriate pressure is applied to a secondary battery cell, an uncharged area may occur in the negative electrode or the electrode plates may lift up, increasing contact resistance.

[0004] Therefore, it is necessary to apply an appropriate pressure to the secondary battery cells, and the maximum deformation of the secondary battery module must be limited to within the allowable displacement of the cell's can-cap. Also, the secondary battery module must be deformed only within the minimum separation distance that must be maintained within the secondary battery pack of the secondary battery module so that the deformation of the secondary battery module does not cause interference with the secondary battery pack case or other secondary battery modules.

[0005] The above information disclosed in this Background of the Invention is intended to enhance the understanding of the background of the present invention only, and may thus include information that does not constitute prior art. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Korean Patent Publication No. 10-2010-0063165 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention provides a secondary battery module that can apply an appropriate pressure to unit cells or a secondary battery module and limit the maximum deformation of the module due to the expansion of the unit cells.

[0008] However, the technical problems that the present invention aims to solve are not limited to the problems mentioned above, and other problems not mentioned should be clearly understood by those skilled in the art from the description of the invention described below. [Means for solving the problem]

[0009] A secondary battery module according to one embodiment of the present disclosure for solving the above technical problems includes one or more cell stacks including a plurality of unit cells, at least one first compression pad disposed between the plurality of unit cells, and a pair of end plates disposed facing each other outside the one or more cell stacks.

[0010] A secondary battery module according to one embodiment of the present disclosure for solving the above technical problems includes one or more cell stacks including a plurality of unit cells, and a pair of end plates arranged facing each other outside the one or more cell stacks, where the one or more cell stacks include a first cell stack and a second cell stack, and an elastic member is arranged between the first cell stack and the second cell stack. Effect of the Invention

[0011] According to the present invention, the end plate is deformed in response to volumetric expansion caused by deterioration of the unit cells, thereby making it possible to maintain a constant pressure on the unit cells and ensure robustness in limiting a maximum deformation amount within a certain range when swelling reaches a high level.

[0012] According to the present invention, by disposing a compression pad between the end plate and the unit cell, pressure can be applied uniformly to one side of the unit cell.

[0013] According to the present invention, by disposing an elastic member between a plurality of cell stacks, it is possible to prevent deformation of the end plates and to ensure a marginal space required for contraction / expansion of the unit cells or cell stacks.

[0014] According to the present invention, by using a unit disc spring as an elastic member, the elastic force of the elastic member for the same volume can be increased compared to the case where a coil spring or the like is used.

[0015] According to the present invention, the variable cylinder fixes the positions of the unit disc springs, and the elastic member can be compressed by an external force.

[0016] However, the effects obtained by the present invention are not limited to the effects described above, and other technical effects not mentioned should be clearly understood by those skilled in the art from the description of the invention described below.

[0017] The following drawings etc. attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention described below, serve to further understand the technical concept of the present invention. Therefore, the present invention should not be analyzed in terms of being limited only to the matters shown in such drawings. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a perspective view illustrating a secondary battery module according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a top view of a secondary battery module in an initial state (Beginning Of Life, BOL) of a unit cell according to an embodiment of the present disclosure. [Diagram 3] FIG. 2 is a top view of a secondary battery module in an end of life (EOL) state of a unit cell according to an embodiment of the present disclosure. [Figure 4] 13A and 13B are diagrams illustrating modified examples of end plates in which grooves are formed according to an embodiment of the present disclosure. [Diagram 5] FIG. 13 is a diagram showing the difference in pressure distribution applied to one side of a unit cell with and without a compression pad. [Figure 6] FIG. 1 is a graph showing a decrease in the initial charge amount due to an increase in the number of charge / discharge cycles of a secondary battery. [Figure 7] FIG. 2 is a top view of a secondary battery module in which an elastic member according to an embodiment of the present disclosure is arranged. [Figure 8] 1A and 1B are side and top views of a unit disc spring included in an elastic member according to an embodiment of the present disclosure. [Figure 9] 1A and 1B are diagrams illustrating an example arrangement of unit disc springs included in an elastic member according to one embodiment of the present disclosure. [Figure 10] 11A and 11B are diagrams illustrating an example in which the length of a variable cylinder changes due to compression of an elastic member according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] <Summary of the Invention> According to one embodiment of the present disclosure, the assembly further includes at least one second compression pad disposed between the pair of end plates and the one or more cell stacks.

[0020] According to an embodiment of the present disclosure, the first compression pad is compressed due to volume expansion caused by changes in the state of charge (SOC) of the plurality of unit cells, thereby preventing deformation of the end plate.

[0021] According to one embodiment of the present disclosure, the first compression pad is made of an elastic material and is reversibly deformable.

[0022] According to an embodiment of the present disclosure, each of the pair of end plates includes a central plate disposed parallel to one surface of the unit cells, and an outer plate bent and extended from the central plate in a direction away from the unit cells in an initial state (Beginning Of Life, BOL) of the unit cells.

[0023] According to one embodiment of the present disclosure, a groove is formed in the bend between the center plate and the outer plates.

[0024] According to one embodiment of the present disclosure, a groove is formed in the inner surface of the end plate.

[0025] According to an embodiment of the present disclosure, the pair of end plates are configured to be deformed in response to volumetric expansion accompanying deterioration of the plurality of unit cells, thereby maintaining constant pressure applied to the plurality of unit cells.

[0026] According to one embodiment of the present disclosure, the pair of end plates are formed of metal and are irreversibly deformed in response to volumetric expansion associated with degradation of the plurality of unit cells.

[0027] According to one embodiment of the present disclosure, at an end of life (EOL) state of the unit cells, the center plate and the outer plate are parallel to one side of the unit cells.

[0028] According to one embodiment of the present disclosure, the one or more cell stacks include a first cell stack and a second cell stack, and an elastic member is disposed between the first cell stack and the second cell stack.

[0029] According to one embodiment of the present disclosure, the elastic member is compressed due to volume expansion accompanying a change in the state of charge of the first cell stack and the second cell stack, thereby preventing deformation of the end plates.

[0030] According to one embodiment of the present disclosure, the elastic member includes a plurality of unit disc springs.

[0031] According to one embodiment of the present disclosure, a plurality of unit disc springs are arranged in series or parallel.

[0032] According to an embodiment of the present disclosure, the plurality of unit disc springs may be arranged in such a manner that a group of unit disc springs arranged in series are arranged in parallel, or a group of disc springs arranged in parallel are arranged in series.

[0033] According to an embodiment of the present disclosure, the elastic member further includes a variable cylinder penetrating through the center of the plurality of unit disc springs.

[0034] According to one embodiment of the present disclosure, the maximum compression amount of the variable cylinder is determined to prevent damage to the multiple unit disc springs.

[0035] According to an embodiment of the present disclosure, the elastic member includes a plurality of unit disc springs, and the arrangement of the plurality of unit disc springs is determined based on at least one of the type, number, or maximum allowable deformation of the secondary battery module.

[0036] According to an embodiment of the present disclosure, the elastic member further includes a pair of plates arranged to face each other outside the elastic member and supporting the elastic member from the outside.

[0037] <Detailed Description of the Invention> Hereinafter, a preferred embodiment of the present disclosure will be described in detail with reference to the accompanying drawings. First, the terms and words used in the present specification and claims should not be analyzed limited to their ordinary and dictionary meanings, but should be interpreted with a meaning and concept that is consistent with the technical idea of ​​the present invention, in accordance with the principle that the inventor can appropriately define the concept of the term in order to best describe his / her invention. Therefore, it should be understood that the configurations shown in the embodiments and drawings described in this specification are only some preferred embodiments of the present invention and do not represent the entire technical idea of ​​the present invention, and that there may be various equivalents and modifications that can replace them at the time of filing this application. In addition, as used in this specification, "comprise" and / or "comprising" specify the presence of a mentioned shape, number, step, operation, member, element, and / or group, and do not exclude the presence or addition of one or more other shapes, numbers, operations, members, elements, and / or groups. In addition, when describing an embodiment of the present invention, "may" and "may" can include "one or more embodiments of the present invention."

[0038] In order to facilitate understanding of the invention, the accompanying drawings are not drawn to scale, and the dimensions of some components may be exaggerated. In addition, the same reference numerals are used to refer to the same components in different embodiments.

[0039] A statement that two comparison objects are "identical" means that they are "substantially identical." Therefore, being substantially identical can include cases where there is a deviation that is considered to be a low level in the art, for example, a deviation within 5%. In addition, in a given region, a certain parameter being uniform can mean that it is uniform in an average sense.

[0040] Although the terms "first", "second", etc. are used to describe various components, it is understood that these components are not limited by these terms. These terms are merely used to distinguish one component from another, and it is understood that a first component can be a second component unless otherwise specified.

[0041] Throughout the specification, unless specifically stated to the contrary, each element may be singular or plural.

[0042] When an arbitrary structure is disposed "on (or on) the "top (or bottom)" of a component or "above (or below)" a component, it does not only mean that the arbitrary structure is disposed in contact with the upper surface (or lower surface) of the component, but also that other structures may be interposed between the component and the arbitrary structure disposed above (or below) the component.

[0043] In addition, when a certain component is described as being "coupled," "coupled," or "connected" to another component, it should be understood that the components can be directly coupled or connected to each other, but that other components can be "interposed" between each component, or each component can be "coupled," "coupled," or "connected" via another component. In addition, when a certain part is said to be electrically coupled to another part, this includes not only the case where they are directly coupled, but also the case where they are coupled via another element in between.

[0044] Throughout the specification, "A and / or B" means A, B, or A and B, unless specifically stated to the contrary. That is, "and / or" includes any and all combinations of the listed items. "C through D" means at least C and at most D, unless specifically stated to the contrary.

[0045] The secondary battery pack includes at least one secondary battery module and a pack housing having an accommodation space for accommodating the at least one secondary battery module.

[0046] The secondary battery module may include a plurality of secondary battery cells and a module housing. The plurality of secondary battery cells may be housed in the module housing in a stacked configuration. The secondary battery cells may include a positive electrode lead and a negative electrode lead. The secondary battery cells may be circular, rectangular, or pouch-shaped, depending on the form of the secondary battery.

[0047] In the secondary battery pack, a cell stack may be stacked to form a module instead of a secondary battery module. The cell stack may be accommodated in an accommodation space of a pack housing or in an accommodation space partitioned by a frame, a partition wall, or the like.

[0048] The secondary battery cells generate a large amount of heat during charging / discharging. The generated heat accumulates in the secondary battery cells, accelerating deterioration of the secondary battery cells. Therefore, the secondary battery pack further includes a cooling member to suppress deterioration of the secondary battery cells. The cooling member is provided at a lower portion of the accommodating space including the secondary battery cells, but is not limited thereto, and may be provided at an upper portion or a side portion depending on the secondary battery pack.

[0049] In the secondary battery cells, exhaust gas generated in the secondary battery cells under abnormal operating conditions known as thermal runaway or thermal events may be discharged to the outside of the secondary battery cells. The secondary battery pack or secondary battery module may include an exhaust port for discharging the exhaust gas in order to prevent damage to the secondary battery pack or module due to the exhaust gas.

[0050] The secondary battery pack may include a secondary battery and a battery management system (BMS) for managing the secondary battery. The secondary battery management system may include a detection device, a balancing device, and a control device. The secondary battery module may include a plurality of cells connected in series or parallel to each other. The secondary battery modules may be connected in series or parallel to each other.

[0051] The detection device can sense the state (voltage, current, temperature, etc.) of the secondary battery to detect state information indicating the state of the secondary battery. The detection device can detect the voltage of each cell or each secondary battery module that constitutes the secondary battery. The detection device can also detect the current flowing through each secondary battery module that constitutes a secondary battery module or a secondary battery pack. The detection device can also detect the temperature of the cell and / or module at at least one point of the secondary battery and / or the ambient temperature.

[0052] The balancing device may perform a balancing operation of the secondary battery module and / or cell group constituting the secondary battery. The control device may receive state information (voltage, current, temperature, etc.) of the secondary battery module from the detection device. The control device may monitor and calculate the state (voltage, current, temperature, SOC (State Of Charge), SOH (State Of Health), etc.) of the secondary battery module based on the state information received from the detection device. The control device may also perform a control function (e.g., temperature control, balancing control, charge / discharge control, etc.) and a protection function (e.g., over-discharge prevention, over-charge prevention, over-current prevention, short circuit, extinguishing function, etc.) based on the state monitoring result. The control device may also perform a wired or wireless communication function with an external device of the secondary battery pack (e.g., an upper controller, a vehicle, a charger, a PCS, etc.).

[0053] The control device may also control the charging / discharging and protection operations of the secondary battery, and for this purpose, the control device may include a charging / discharging control unit, a balance control unit, and a protection unit.

[0054] A secondary battery management system is a system that monitors the status of a secondary battery and performs diagnostic, control, communication, and protection functions. It can calculate the charge / discharge status, calculate the life or state of health (SOH) of the secondary battery, cut off power to the secondary battery when necessary (relay control), control heat management (cooling, heating, etc.), perform a high-voltage interlock function, and detect or calculate insulation and short-circuit status.

[0055] The relay may be a mechanical contactor that is turned on and off by the magnetic force of a coil, or a semiconductor switch such as a Metal Oxide Semiconductor Field Effect Transistor (MOSFET).

[0056] The relay control is a function that cuts off the power supply from the secondary battery when a problem occurs in the vehicle and the secondary battery system, and may include one or more relays and a precharge relay at each of the positive and negative terminals.

[0057] Pre-charge control has the risk of generating an inrush current in the high voltage capacitor on the inverter input side when the secondary battery is connected as a load. In order to prevent the generation of an inrush current, the pre-charge control can have a function of operating the pre-charge relay and connecting it to a pre-charge resistor before connecting the main relay when the vehicle is started.

[0058] The high voltage interlock is a circuit that uses a small signal to detect whether all high voltage parts are connected to all vehicle systems, and has the function of forcibly opening a relay if an open occurs at any point on any loop.

[0059] In the present disclosure, the beginning of life (BOL) state of a secondary battery cell may indicate the beginning of the life of the secondary battery. In general, a secondary battery may have an optimal performance level and capacity at the beginning of its life. The end of life (EOL) state of a secondary battery cell may indicate a state where the life of the secondary battery has ended and the secondary battery can no longer provide a desired level of performance and capacity. For example, the end of life state of a secondary battery cell may indicate a point in time when the performance of the secondary battery cell has deteriorated to such an extent that it is determined that the secondary battery cell is no longer suitable for its original use.

[0060] The swelling of a secondary battery cell may refer to a physical expansion of the size of the secondary battery cell due to internal chemical reactions and other factors. The degree of swelling of the secondary battery cell may vary throughout the life cycle of the secondary battery cell, including the initial state and the end state. Specifically, the swelling of the secondary battery cell in the initial state of the secondary battery cell may generally be absent or minimal. In this case, the internal components and materials of the secondary battery cell may be tightly packed without damage. The secondary battery cell may gradually expand and swell as it ages over time due to repeated charging and discharging. This swelling phenomenon may occur due to various factors such as chemical reactions, side reactions, and changes in the secondary battery electrode and electrolyte structure. As the life of the secondary battery cell approaches the end state, the degree of swelling / swelling of the secondary battery may become higher. Specifically, the swelling may increase when the deterioration process and irreversible changes in the secondary battery cell accumulate. The swelling of the secondary battery cell affects the performance, safety, and overall functionality of the secondary battery cell. Moreover, excessive expansion may cause pressure build-up, mechanical stress on the secondary battery, damage, etc. Therefore, it is important to resolve the expansion problem of secondary battery cells in order to ensure safe and effective operation of the secondary battery.

[0061] FIG 1 is a perspective view showing a secondary battery module 100 according to an embodiment of the present disclosure. Referring to FIG 1, the secondary battery module 100 according to the present invention includes a plurality of unit cells 10 having terminal parts 11, 12 and arranged in one direction, a connection tab 20 connecting a unit cell 10a and an adjacent unit cell 10b, and a protection circuit module 30 having one end connected to the connection tab 20. The protection circuit module 30 may be a secondary battery management system (BMS). The connection tab 20 includes a body part contacting the terminal parts 11, 12 between the adjacent unit cells 10a, 10b, and an extension part extending from the body part and connected to the protection circuit module 30. The connection tab 20 may be a bus bar.

[0062] First, the unit cell 10 may include a secondary battery case, an electrode assembly housed in the secondary battery case, and an electrolyte. The electrode assembly and the electrolyte react electrochemically to generate energy. One side of the unit cell 10 may include terminals 11 and 12 electrically connected to a connection tab 20, and a vent 13 serving as a passage for discharging gas generated therein. The terminals 11 and 12 of the unit cell 10 may be a positive terminal 11 and a negative terminal 12 having different polarities, and the terminals 11 and 12 of adjacent unit cells 10a and 10b may be electrically connected in series or in parallel by a connection tab 20 described below. Meanwhile, although the above description is given by way of an example of a series connection, it is understood that various connection structures may be adopted as necessary without being limited thereto. In addition, the number and arrangement of the unit cells are not limited to the structure shown in FIG. 1 and may be changed as necessary. For example, the secondary battery module 100 may include one or more cell stacks including a plurality of unit cells, and the one or more cell stacks may be arranged spaced apart from each other.

[0063] A plurality of unit cells 10 may be arranged in one direction such that the wide surfaces of the unit cells 10 face each other, and the arranged plurality of unit cells 10 may be fixed by housings 61, 62, 63, 64. The housings 61, 62, 63, 64 may include a pair of end plates 61, 62 that face the wide surfaces of the unit cells 10 and are arranged to face each other outside the plurality of unit cells (or one or more cell stacks), a side plate 63 that connects the pair of end plates 61, 62, and a bottom plate 64. The side plate 63 may support the side of the unit cell 10, and the bottom plate 64 may support the bottom of the unit cell 10. In addition, the pair of end plates 61, 62, the side plate 63, and the bottom plate 64 may be connected by a connecting method such as bolting or welding.

[0064] In one embodiment, a first compression pad 65 can be disposed between the unit cells 10. Additionally or alternatively, a second compression pad 66 can be disposed between the pair of end plates 61, 62 and the unit cells 10. The compression pads 65, 66 are made of an elastic material and are reversibly deformable. Additionally, the compression pads 65, 66 can include a flame retardant material and / or a cooling material.

[0065] The end plates 61, 62 may be made of a metal such as stainless steel or aluminum, a carbon fiber material, a polymer, or a reinforced plastic.

[0066] In one embodiment, the end plates 61, 62 may include a central plate 61a, 62a arranged parallel to one surface (e.g., a wide surface) of the unit cell 10, and outer plates 61b, 62b bent and extended from the central plate 61a, 62a in a direction away from the unit cells in an initial state (Beginning Of Life, BOL) of the unit cells. As a result, the end plates 61, 62 are deformed in response to volumetric expansion caused by deterioration of the unit cells, thereby maintaining a constant pressure applied to the unit cells and ensuring robustness in limiting the maximum deformation amount within a certain range when swelling occurs at a high level. The process of deforming the end plates 61, 62 will be described in detail below with reference to Figures 2 and 3.

[0067] The protection circuit module 30 may be mounted with electronic components and a protection circuit, and may be electrically connected to a connection tap 20, which will be described later. The protection circuit module 30 includes a first protection circuit module 30a and a second protection circuit module 30b extending from different positions along a direction in which the unit cells 10 are arranged. In this case, the first protection circuit module 30a and the second protection circuit module 30b may be positioned parallel to each other while being spaced apart from each other at a certain interval, and may be electrically connected to the adjacent connection tap 20. For example, the first protection circuit module 30a may be extended on one side of the unit cells 10 along a direction in which the unit cells 10 are arranged, and the second protection circuit module 30b may be extended on the other side of the unit cells 10 along a direction in which the unit cells 10 are arranged. In this case, the second protection circuit module 30b may be positioned to be spaced apart from the first protection circuit module 30a across the vent 13, but may be arranged parallel to the first protection circuit module 30a. In this manner, the two protection circuit modules are arranged parallel to each other at a distance from each other along the direction in which the unit cells are arranged, thereby minimizing the area of ​​a PCB (Printed Circuit Board) constituting the protection circuit module. By configuring a protection circuit module from each of the two protection circuit modules, unnecessary PCB area can be minimized. The first protection circuit module 30a and the second protection circuit module 30b may be connected to each other by a conductive connection member 50. At this time, one side of the connection member 50 is connected to the first protection circuit module 30a, and the other side is connected to the second protection circuit module 30b, thereby electrically connecting the two protection circuit modules.

[0068] The connection can be made by one of the following methods: soldering, resistance welding, laser welding or projection welding.

[0069] The connecting member 50 may be, for example, an electric wire. The connecting member 50 may be made of a material having elasticity or flexibility. The connecting member 50 can be used to check and manage whether the voltage, temperature, and current of the plurality of unit cells 10 are normal. That is, information on the voltage, current, temperature, etc. transferred from the adjacent connection tap to the first protection circuit module and information on the voltage, current, temperature, etc. transferred from the adjacent connection tap to the second protection circuit module can be integrated and managed by the protection circuit module through the connecting member.

[0070] In addition, when the unit cell 10 expands, the elasticity or flexibility of the connecting member 50 absorbs the impact, thereby preventing damage to the first and second protection circuit modules 30a and 30b.

[0071] Furthermore, the shape and structure of the connecting member 50 are not limited to the shape shown in FIG.

[0072] In this way, since the protection circuit module 30 is provided as the first and second protection circuit modules 30a and 30b, the area of ​​the PCB constituting the protection circuit module can be minimized, and space can be secured within the secondary battery module. This not only facilitates the connection between the connection tap 20 and the protection circuit module 30, but also facilitates repairs when an abnormality is detected in the secondary battery module, thereby improving work efficiency.

[0073] 2 is a top view of a secondary battery module 200 in an initial state (Beginning Of Life, BOL) of a unit cell 210 according to an embodiment of the present disclosure. The secondary battery module 200 may include one or more cell stacks including a plurality of unit cells 210, at least one first compression pad 220 disposed between the plurality of unit cells 210, and a pair of end plates 240, 250 disposed to face each other on the outside of the one or more cell stacks.

[0074] In one embodiment, the first compression pad 220 can prevent deformation of the end plate by being compressed due to volume expansion caused by a change in the State Of Charge (SOC) of the plurality of unit cells 210. For example, the volume of the plurality of unit cells 210 may expand when fully charged (SOC 100%) compared to when fully discharged (SOC 0%). In this case, the first compression pad 220 can be compressed due to the volume expansion of the plurality of unit cells 210.

[0075] In one embodiment, the second compression pad 230 may be disposed between the pair of end plates 240, 250 and the one or more cell stacks, so that the pressure applied by the end plates 240, 250 may be uniformly transferred to one side of the plurality of unit cells 210.

[0076] The compression pads 220, 230 may be made of a resilient material and may be reversibly deformable. For example, the compression pads 220, 230 may be made of a material such as, but not limited to, urethane.

[0077] Each of the pair of end plates 240, 250 may include a central plate 240a, 250a arranged parallel to one surface (e.g., a wide surface) of the unit cell 210, and outer plates 240b, 250b bent and extended from the central plate 240a, 250a in a direction away from the unit cells 210 in an initial state (Beginning Of Life, BOL) of the unit cells 210. In one embodiment, a groove may be formed in a bent portion between the central plate 240a, 250a and the outer plate 240b, 250b. In this case, the groove may be formed on an inner surface of the end plate 240, 250.

[0078] In one embodiment, the bending angle of the outer plates 240b, 250b may vary depending on the type of unit cell (e.g., all-solid-state secondary battery or lithium ion secondary battery), the maximum deformation amount of the secondary battery module, and the pressure applied to the unit cell. For example, the bending angle may be larger as the unit cell included in the secondary battery module 200 generates a higher swelling pressure, thereby absorbing the higher swelling pressure. The thickness of the end plates 240, 250 may also be determined depending on the maximum deformation amount of the secondary battery module and the pressure applied to the unit cell.

[0079] 2, the end plates 240, 250 may be formed in various structures to ensure robustness in limiting the maximum deformation amount within a certain range when a high level of swelling force occurs at the end of life (EOL) of a plurality of unit cells. For example, the end plates 240, 250 may be formed in an arch or dome shape, or may further include a plate extending from the outer plates 240b, 250b.

[0080] 3 is a top view of a secondary battery module 300 in an end of life (EOL) state of a unit cell according to an embodiment of the present disclosure. The details described in FIG. 2 regarding the unit cell 310 of the secondary battery, the first compression pad 320, and the second compression pad 330 will be omitted.

[0081] The end plates 340, 350 may be configured to be deformed in response to volumetric expansion caused by degradation of the plurality of unit cells 310 and to maintain a constant pressure applied to the deformed plurality of unit cells 310. The pair of end plates 340, 350 may be made of metal and may be plastically deformed. Thus, the pair of end plates 340, 350 may be irreversibly deformed in response to volumetric expansion caused by degradation of the plurality of unit cells 310.

[0082] In an end of life (EOL) state of the plurality of unit cells 310, a high level of swelling force may be generated due to the expansion of the plurality of unit cells 310. Accordingly, in the end of life (EOL) state of the plurality of unit cells 310, the center plates 340a, 350a and the outer plates 340b, 350b are deformed parallel to one surface of the plurality of unit cells 310, thereby limiting the maximum deformation of the secondary battery module while continuously applying an appropriate pressure to the plurality of unit cells 310. With this configuration, the end plates 340, 350 can provide a constant pressure from the initial state to the end state of the secondary battery cell.

[0083] At the end of life (EOL) of the unit cells 310, the compression pads 320, 330 are compressed due to volume expansion caused by a change in the state of charge of the unit cells 310, and absorb the pressure applied to the end plates 340, 350, thereby preventing deformation of the end plates.

[0084] FIG. 4 is a diagram showing a modified example of an end plate 410 having a groove 412 according to an embodiment of the present disclosure. The end plate 410 may include a central plate 240a arranged parallel to one surface of the unit cells, and an outer plate 240b bent and extended in a direction away from the unit cells. The end plate 410 is easily deformed in response to volumetric expansion (external force applied to the right in FIG. 4) caused by deterioration of the unit cells, so that the groove 412 may be formed at the bent portion between the central plate 240a and the outer plate 240b. In this case, the groove 412 may be formed on the inner surface of the end plate 410. The end plate 410 may represent the state of the end plate in the beginning of life (BOL) state of the unit cells.

[0085] By forming the grooves 412 in the end plate 410, the end plate 420, which is deformed in response to the volumetric expansion caused by the deterioration of the unit cells, may become parallel to one surface of the unit cells. For example, as the unit cells expand due to deterioration, the center plate 240a may move parallel to the expansion direction of the unit cells, and the outer plate 240b connected to the center plate 240a may move to become parallel to one surface of the unit cells. The deformed end plate 420 may represent the state of the end plate at the end of life (EOL) of the unit cells.

[0086] Alternatively, the end plates 410 may be deformed by forming hinges at the bends between the central plate 240a and the outer plates 240b.

[0087] 5 shows the difference in pressure distribution applied to one side of a unit cell with and without a compression pad. A first color map 510 shows the distribution of pressure applied to one side of a unit cell when no compression pad is placed between an end plate and a unit cell, and between groups of unit cells. A second color map 520 shows the distribution of pressure applied to one side of a unit cell when a compression pad is placed between an end plate and a unit cell, and between groups of unit cells.

[0088] As shown in the figure, in the first color map 510, it can be seen that low pressure is applied to the outer side of the unit cell, while high pressure is applied to the inner side. That is, it can be seen that pressure is not applied uniformly to the unit cells in the first color map 510. On the other hand, it can be seen that in the second color map 520, pressure is applied uniformly to one side of the unit cells by using compression pads. That is, by disposing compression pads between the end plates and the unit cells and between the unit cell groups, pressure is applied uniformly to one side of the unit cells.

[0089] 6 is a graph 600 showing the decrease in the initial charge amount as the number of charge / discharge cycles of a secondary battery increases. In the graph 600, it can be seen that the deterioration of the secondary battery progresses most slowly when only one cell is used (Single Cell). On the other hand, it can be seen that the deterioration of the secondary battery progresses more quickly in a secondary battery module including multiple secondary battery cells (15S1P Module) compared to when only one cell is used (Single Cell) due to the swelling phenomenon of the secondary battery.

[0090] On the other hand, when the compression pad (1.68T or 3.6T) and end plate (DF-JIG(1.68T), DF-JIG(3.6T)) according to the present disclosure are applied to a secondary battery module including a plurality of secondary battery cells, it can be confirmed that the lifespan of the secondary battery module is significantly improved. Also, when the thickness of the compression pad is increased from 1.68T (DF-JIG(1.68T)) to 3.6T (DF-JIG(3.6T)), it can be confirmed that the lifespan of the secondary battery module is further improved. That is, it can be confirmed that the greater the compression thickness of the compression pad, the longer the lifespan of the secondary battery.

[0091] 7 is a top view of a secondary battery module 700 in which an elastic member 750 according to an embodiment of the present disclosure is arranged. Regarding the end plates 730 and 740, the same contents as those described above will not be described.

[0092] The elastic member 750 may be disposed between a first cell stack 710 including a plurality of unit cells and a second cell stack 720 including a plurality of unit cells. The elastic member 750 is compressed due to volumetric expansion caused by a change in the state of charge of the first cell stack 710 and the second cell stack 720, thereby preventing deformation of the end plates 730, 740 while securing a margin required for contraction / expansion of the unit cells or the cell stacks 710, 720. Specifically, the elastic member 750 is used when the volumetric expansion of the cells caused by a change in the state of charge is large, thereby absorbing pressure caused by the expansion.

[0093] In one embodiment, the elastic member 750 may include a plurality of unit disc springs 752. The specific structure of the unit disc springs will be described in detail later with reference to FIG.

[0094] In one embodiment, the plurality of unit disc springs 752 may be arranged in series or in parallel, or a group of unit disc springs arranged in series may be arranged in parallel, or a group of disc springs arranged in parallel may be arranged in series, thereby adjusting the elastic force and / or the compression length of the elastic member 750. This will be described in detail later with reference to FIG.

[0095] In one embodiment, the elastic member 750 may include variable cylinders 754, 756 that pass through the center of the plurality of unit disc springs 752. The variable cylinders 754, 756 may be compressed together when the plurality of unit disc springs 752 are compressed. For example, a protrusion 758 formed on one side of the second cylinder member 756 may be inserted into the hollow of the first cylinder member 754 to shorten the length of the variable cylinders 754, 756. This will be described in detail later with reference to FIG.

[0096] Additionally, a pair of plates (not shown) may be further disposed so as to face each other on the outer side of the elastic member 750. The pair of plates facing each other may support the elastic member 750 on the outer side.

[0097] Additionally or alternatively, a resilient member 750 may be disposed between the first end plate 730 and the first cell stack 710 and / or between the second end plate 740 and the second cell stack 720.

[0098] 7 shows the use of multiple unit disc springs 752 and variable cylinders 754, 756 together, but is not limited thereto. For example, only variable cylinders 754, 756 or multiple unit disc springs 752 may be used.

[0099] 8 is a side view and a top view of a unit disc spring 800 included in an elastic member according to an embodiment of the present disclosure. The lower part of the unit disc spring 800 has a first diameter d o The hollow 820 formed in the upper portion of the unit disk spring 800 has a second diameter d i When the unit disc spring 800 is compressed, the inclined portion 810 may be flush with the hollow 820.

[0100] The variable height h of the unit disc spring 800 or the inclination of the inclined portion 810 and / or the thickness t of the unit disc spring 800 may be changed based on the required performance of the elastic member disposed between the multiple cell stacks. For example, when the variable height h increases, the elastic force of the elastic member may increase.

[0101] By using the unit disc spring 800 as an elastic member, the elastic force of the elastic member for the same volume can be increased compared to when a coil spring or the like is used.

[0102] 9 is a diagram showing exemplary arrangements 910, 920, 930 of unit disc springs included in an elastic member according to an embodiment of the present disclosure. The first arrangement 910 shows a structure in which a plurality of unit disc springs are arranged in parallel. In this case, the maximum compression distance is the same compared to when one unit disc spring is used, but the elastic force required for compression can increase in proportion to the number of unit disc springs used.

[0103] The second arrangement 920 shows a structure in which multiple unit disc springs are arranged in series. In this case, the maximum compression distance increases in proportion to the number of unit disc springs used compared to when one unit disc spring is used, but the elastic force required for compression may be the same.

[0104] The third arrangement 930 shows a structure in which a plurality of unit disc springs are arranged in series in a group of unit disc springs arranged in parallel, or in series in a group of parallel disc springs, etc. In this case, compared to the case where one unit disc spring is used, the maximum compression distance increases in proportion to the number of unit disc springs arranged in series, and the elastic force required for compression increases in proportion to the number of unit disc springs arranged in parallel.

[0105] The arrangement of the unit disc springs may vary based on the required performance of the elastic member that includes the unit disc springs. For example, the arrangement of the unit disc springs may be designed based on the type of unit cell (e.g., all-solid-state secondary battery or lithium ion secondary battery), the number of unit cells, the maximum deformation amount of the secondary battery module, the pressure applied to the unit cells, etc. For example, the pressure applied to the unit cells varies depending on the type of unit cell, and the pressure applied by the elastic member may be adjusted by the arrangement of the disc springs so that the pressure is applied to the unit cells.

[0106] 10 is a diagram showing an example in which the length of variable cylinders 1014, 1016 changes due to compression of an elastic member 1010 according to an embodiment of the present disclosure. The variable cylinders 1014, 1016 penetrating the centers of a plurality of unit disc springs 1012 include a first cylinder member 1014 and a second cylinder member 1016, and the second cylinder member 1016 can include a protrusion 1018.

[0107] In the compressed elastic member 1030, the length of the variable cylinders 1014, 1016 can be shortened by inserting the protrusion 1018 provided on one side of the second cylinder member 1016 into the hollow of the first cylinder member 1014. As a result, the elastic member 1030 can be compressed by an external force while the variable cylinders 1014, 1016 fix the positions of the multiple unit disc springs 1012.

[0108] In one embodiment, the maximum compression of the variable cylinders 1014, 1016 can be determined to prevent breakage of the plurality of unit disc springs 1012. For example, the length of the protrusion 1018 (i.e., the maximum compression of the variable cylinders 1014, 1016) can be less than a threshold length that would cause the plurality of unit disc springs 1012 to break.

[0109] Alternatively, the elastic members 1010, 1030 are arranged on both sides of the plurality of unit disc springs and include a pair of opposing plates and one cylinder member, with a hollow formed in one of the plates and at least a portion of the cylinder member being drawn into the hollow of the plate, thereby allowing the length of the elastic member to be adjusted.

[0110] Although the present invention has been described above with reference to limited examples and drawings, it is to be understood that the present invention is not limited thereto, and various modifications and variations can be made by those having ordinary knowledge in the technical field to which the present invention pertains within the technical spirit of the present invention and the equivalent scope of the claims. [Explanation of symbols]

[0111] 100 Secondary battery module 10 Unit Cell 11 Positive terminal 12 Negative terminal 13. Vent 20 Connecting Taps 30 Protection Circuit Module 50 Connecting member 61, 62 End plate 63 Side Plate 64 Bottom Plate 65 First Compression Pad 66 Second Compression Pad

Claims

1. A secondary battery module, one or more cell stacks including a plurality of unit cells; at least one first compression pad disposed between the plurality of unit cells; a pair of end plates arranged to face each other outside the one or more cell stacks.

2. The secondary battery module of claim 1 , further comprising at least one second compression pad disposed between the pair of end plates and the one or more cell stacks.

3. The secondary battery module of claim 1 , wherein the first compression pad is compressed due to volume expansion caused by a change in state of charge (SOC) of the unit cells, thereby preventing deformation of the end plates.

4. The secondary battery module according to claim 1 , wherein the first compression pad is made of an elastic material and is reversibly deformable.

5. Each of the pair of end plates is a central plate disposed parallel to one surface of the unit cell; 2 . The secondary battery module of claim 1 , further comprising: an outer plate bent and extending from the central plate in a direction away from the unit cells when the unit cells are in an initial state (BOL).

6. The secondary battery module according to claim 5 , wherein a groove is formed at a bent portion between the central plate and the outer plate.

7. The secondary battery module according to claim 6 , wherein the grooves are formed on inner surfaces of the end plates.

8. 6. The secondary battery module of claim 5, wherein the pair of end plates are configured to deform in response to volumetric expansion caused by deterioration of the unit cells, thereby maintaining a constant pressure applied to the unit cells.

9. The secondary battery module of claim 8 , wherein the pair of end plates are made of metal and are irreversibly deformed in response to volumetric expansion caused by deterioration of the plurality of unit cells.

10. The secondary battery module of claim 5 , wherein the center plate and the outer plate are parallel to the one surface of the unit cells in an end-of-life (EOL) state of the unit cells.

11. the one or more cell stacks include a first cell stack and a second cell stack; The secondary battery module according to claim 1 , wherein an elastic member is disposed between the first cell stack and the second cell stack.

12. The secondary battery module of claim 11 , wherein the elastic member is compressed due to volume expansion caused by a change in a state of charge of the first cell stack and the second cell stack, thereby preventing deformation of the end plates.

13. The secondary battery module of claim 11 , wherein the elastic member includes a plurality of unit disc springs.

14. The secondary battery module according to claim 13 , wherein the plurality of unit disc springs are arranged in series or in parallel.

15. The secondary battery module according to claim 13 , wherein the plurality of unit disc springs are arranged in such a manner that a group of unit disc springs arranged in series are arranged in parallel, or a group of unit disc springs arranged in parallel are arranged in series.

16. The secondary battery module of claim 13 , wherein the elastic member further comprises a variable cylinder passing through a center of the plurality of unit disc springs.

17. The secondary battery module of claim 16 , wherein a maximum compression amount of the variable cylinder is determined to prevent damage to the plurality of unit disc springs.

18. A secondary battery module, one or more cell stacks including a plurality of unit cells; a pair of end plates disposed opposite each other on the outside of the one or more cell stacks; the one or more cell stacks include a first cell stack and a second cell stack; a rechargeable battery module, wherein an elastic member is disposed between the first cell stack and the second cell stack.

19. The elastic member includes a plurality of unit disc springs, The secondary battery module of claim 18 , wherein an arrangement of the unit disc springs is determined based on at least one of a type and a number of the unit cells, and a maximum allowable deformation of the secondary battery module.

20. The secondary battery module of claim 18 , further comprising a pair of plates disposed opposite each other on outer sides of the elastic member and supporting the elastic member from the outside.

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