Battery pack and temperature control method of battery pack

Abstract

To provide a battery pack that protects a collector terminal from a heat generation due to an increase in temperature in a steady use state and suppresses the fusion of a fusion part in the case where the fusion part is formed at the collector terminal that electrically connects an external terminal of a cell and an electrode body, and provide a temperature control method of the battery pack.SOLUTION: A battery pack includes: a cell containing a battery case, an electrode body that is housed in an internal part of the battery case; an external terminal having at least one part arranged at an external part of the battery case, a collector terminal in which a fusion part that can be fused at a temperature equal to or higher than a temperature of a fusion is formed and which electrically connects the electrode body to the external terminal; a temperature detection part that detects the temperature of the collector terminal; a current detection part that detects a current input / output to / from a battery including the cell; and a temperature control device that estimates a temperature change of the fusion part on the basis of the temperature of the collector terminal and a detection result of the current, and performs an input / output limitation of the battery or cooling of the battery in the case where the temperature change of the fusion part estimated is a predetermined temperature change threshold value or higher.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a battery pack and a temperature control method for the battery pack, and in particular to a battery pack having a cell including a battery case, an electrode body housed inside the battery case, an external terminal at least a part of which is disposed outside the battery case, and a current collecting terminal that electrically connects the electrode body to the external terminal, and a temperature control method for the battery pack. [Background technology]

[0002] A secondary battery is generally mounted in a vehicle in the form of a battery pack. The battery pack includes a secondary battery, sensors for detecting the state of the secondary battery (e.g., current, voltage, and temperature), and a control device. For such a battery pack, a technique is known for protecting the secondary battery from heat generation due to temperature rise during normal use of the battery pack by limiting input / output of the battery pack based on the temperature of the battery pack estimated based on the detection results of each sensor.

[0003] Patent Document 1 discloses a battery pack input / output control device that is a control device for processing input / output limitations of a battery pack, including an inside / outside temperature difference estimation module that estimates the temperature difference between the surface temperature and the inside temperature of the battery pack as a maximum temperature estimation unit that estimates the maximum temperature inside the battery pack, and an R-attributed temperature difference estimation module that estimates the temperature difference caused by the difference in internal resistance of each unit battery. Here, Patent Document 1 discloses that the estimation of the above-mentioned inside / outside temperature difference and R-attributed temperature difference takes into account the intake air temperature, current load, and cooling air volume, and that the above-mentioned control device includes an input / output limiting unit that limits the input / output power of the battery pack based on the estimated maximum temperature. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-222133 A Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, one of the ideas for improving the safety of secondary batteries is related to a current collecting terminal that electrically connects an external terminal, at least a part of which is disposed outside a battery case, and an electrode body housed inside the battery case in a cell (single cell) of a secondary battery. For example, by providing a fusing part that can be melted by an overcurrent in a part of the current collecting terminal, when an overcurrent flows through the cell, the current collecting terminal generates heat, causing the fusing part to melt and cut off the current path. The fusing part that functions as a fuse in this way is configured so that heat is locally concentrated when an overcurrent flows through the cell, and therefore the temperature may rise significantly. Therefore, it is desirable to monitor the temperature of the current collecting terminal in order to protect the current collecting terminal from heat generated by a temperature rise during normal use of the battery pack and to suppress melting of the fusing part. However, the technology described in Patent Document 1 has a problem in that the temperature of the current collecting terminal is not monitored.

[0006] The present invention has been made to solve such problems, and aims to provide a battery pack and a temperature control method for a battery pack that, when a fusion portion is formed in a collector terminal that electrically connects the external terminal of a cell to an electrode body, protects the collector terminal from heat generation due to temperature rise during steady-state use and suppresses fusion of the fusion portion. [Means for solving the problem]

[0007] A battery pack according to one embodiment includes at least one cell including a battery case, an electrode body stored inside the battery case, an external terminal at least a portion of which is disposed outside the battery case, and a current collecting terminal in which a fusion portion that can be fused at a temperature equal to or higher than the fusion temperature is formed and which electrically connects the electrode body to the external terminal, a temperature detection unit that detects the temperature of the current collecting terminal, a current detection unit that detects a current input to and output from a battery including the cell, and a temperature control device that estimates a temperature change in the fusion portion based on the detection results of the temperature of the current collecting terminal detected by the temperature detection unit and the current detected by the current detection unit, and that limits input / output to and from the battery or cools the battery if the estimated temperature change in the fusion portion is equal to or higher than a predetermined temperature change threshold.

[0008] A temperature control method for a battery pack according to one embodiment includes a step of estimating a temperature change of a fusion part based on a detection result obtained by detecting a temperature of a current collecting terminal of at least one cell including a battery case, an electrode body stored inside the battery case, an external terminal at least a portion of which is disposed outside the battery case, and a current collecting terminal in which a fusion part that can be fused at a temperature equal to or higher than a fusion temperature is formed and which electrically connects the electrode body to the external terminal, and a current input / output to / from a battery including the cell; and a step of restricting input / output of the battery or cooling the battery if the estimated temperature change of the fusion part is equal to or higher than a predetermined temperature change threshold. Effect of the Invention

[0009] The present invention makes it possible to provide a battery pack and a temperature control method for a battery pack that, when a fusion portion is formed in a collector terminal that electrically connects an external terminal of a cell and an electrode body, protects the collector terminal from heat generation due to temperature rise during steady-state use and suppresses fusion of the fusion portion. [Brief description of the drawings]

[0010] [Figure 1] 1 is a diagram showing a vehicle equipped with a battery pack according to a first embodiment. [Diagram 2] 2 is a cross-sectional view showing one cell included in the battery pack shown in FIG. 1. [Diagram 3] 4 is a flowchart showing a temperature control process of the battery pack according to the first embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] First embodiment Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. However, the present disclosure is not limited to the following embodiment. In addition, in order to clarify the description, the following description and drawings are appropriately simplified. What is shown in the drawings is only a part of the whole, and in reality, many other configurations that are not shown are included. In the following description, the same or equivalent elements are given the same reference numerals, and duplicated descriptions are omitted.

[0012] First, Fig. 1 is a diagram showing a vehicle equipped with a battery pack according to the first embodiment. The vehicle 100 includes a battery pack 10 including a battery 200. The vehicle 100 is an electric vehicle configured to run using power stored in the battery 200. The vehicle 100 is an electric vehicle that does not include an engine. However, the vehicle 100 is not limited to an electric vehicle, and may be a hybrid vehicle equipped with an engine (internal combustion engine). The ECU 300 according to this embodiment corresponds to an example of a "temperature control device" according to the present disclosure.

[0013] The vehicle 100 further includes a motor generator (MG) 11, a power control unit (PCU) 12, and a system main relay (SMR) 13.

[0014] SMR 13 is provided in a current path connecting battery 200 and PCU 12. SMR 13 is, for example, an electromagnetic mechanical relay. The state (connected / disconnected) of SMR 13 is controlled by ECU 300. When SMR 13 is in the ON state (connected state), power can be exchanged between battery 200 and PCU 12, and when SMR 13 is in the OFF state (disconnected state), power cannot be exchanged between battery 200 and PCU 12. SMR 13 is set to the ON state when the vehicle is running.

[0015] The MG 11 is, for example, a three-phase AC motor generator. The MG 11 is configured to be driven by the PCU 12 and rotate the drive wheels 15 of the vehicle 100. The PCU 12 is configured to include, for example, a control device including a processor, an inverter, and a converter (none of which are shown). The control device of the PCU 12 is configured to receive instructions (control signals) from the ECU 300 and control the inverter and converter of the PCU 12 according to the instructions. The output torque of the MG 11 is transmitted to the drive wheels 15 via the power transmission gear 14 which serves as a reduction gear. The MG 11 is also configured to perform regenerative power generation and supply the generated power to the battery 200.

[0016] The battery pack 10 includes a battery 200, a temperature sensor 410, a current sensor 420, and an ECU 300. The battery 200 functions as a secondary battery. In this embodiment, an assembled battery including a plurality of electrically connected lithium ion batteries is adopted as the battery 200. Each secondary battery constituting the assembled battery is a cell 201. In this embodiment, each lithium ion battery constituting the battery 200 corresponds to the cell 201. Note that the secondary battery included in the battery pack 10 is not limited to a lithium ion battery, and may be another secondary battery (for example, a nickel-metal hydride battery). As the secondary battery, a liquid electrolyte secondary battery or an all-solid-state secondary battery may be adopted. In this embodiment, a liquid electrolyte secondary battery is adopted as the secondary battery.

[0017] The battery 200 includes a plurality of cells 201 stacked in a stacking direction along the thickness direction of the cells 201, a plurality of bus bars (not shown) that electrically connect adjacent cells 201 in the stacking direction, and the like. In this embodiment, the battery 200 includes a plurality of cells 201 connected in parallel by the bus bars. Note that the connection method of the plurality of cells 201 included in the battery 200 is not limited to parallel connection, and may be series connection, etc.

[0018] Here, the cell 201 will be described in detail with reference to FIG. 2. FIG. 2 is a cross-sectional view showing one cell included in the battery pack shown in FIG. 1. The dashed line in FIG. 2 shows a positive electrode current collector terminal 250 seen from above in the height direction of the cell 201. As shown in FIG. 2, the cell 201 includes a battery case 210, an electrode body 220 housed inside the battery case 210, and positive and negative external terminals 230, 240 at least a part of which is disposed outside the battery case 210. The cell 201 includes positive and negative current collector terminals 250, 260 that electrically connect the electrode body 220 to the positive and negative external terminals 230, 240. Furthermore, the cell 201 has an electrolyte (not shown) such as a nonaqueous electrolyte inside the battery case 210. There is no particular limitation on the type of electrolyte as long as it does not impair the performance of the cell 201, and it can be appropriately selected according to the application.

[0019] The battery case 210 is a flat rectangular container having a rectangular case body 211 with an opening at the top and a plate-like lid 212 that closes the opening of the case body 211. The inside of the battery case 210 can be sealed by joining the lid 212 by welding or the like to the case body 211 that houses the electrode body 220 and the like inside. The battery case 210 is made of a metal material having a required strength, such as aluminum, an aluminum alloy, or stainless steel. The lid 212 may have an injection port for injecting an electrolyte into the battery case 210, a gas exhaust valve for exhausting gas inside the battery case 210 when the internal pressure of the battery case 210 increases, and the like.

[0020] The electrode body 220 is a power generating element accommodated inside the battery case 210 in a state where it is covered with an insulating film (not shown) or the like. The electrode body 220 has a positive electrode, a negative electrode, and a separator interposed between the positive and negative electrodes. The electrode body 220 is a laminated electrode body in which rectangular sheet-like positive electrodes and negative electrodes are alternately laminated with rectangular sheet-like separators interposed therebetween. The structure of the electrode body 220 is not particularly limited, and various structures that can be adopted in lithium ion secondary batteries can be adopted without restriction. For example, the electrode body 220 may be a wound electrode body in which long sheet-like positive electrodes and negative electrodes are laminated with two long sheet-like separators interposed therebetween and wound.

[0021] The positive electrode has a foil-shaped positive electrode collector such as an aluminum foil, and a positive electrode active material layer formed on the surface (preferably both surfaces) of the positive electrode collector. The positive electrode active material layer contains various materials such as a positive electrode active material, a binder, and a conductive material. The material contained in the positive electrode active material layer can be any material that can be used for the negative electrode of a lithium ion secondary battery, without any particular limitation.

[0022] The negative electrode has a foil-shaped negative electrode collector such as copper foil, and a negative electrode active material layer formed on the surface (preferably both surfaces) of the negative electrode collector. The negative electrode active material layer contains various materials such as a negative electrode active material and a binder. The material contained in the negative electrode active material layer can be any material that can be used for the negative electrode of a lithium ion secondary battery, without any particular limitation.

[0023] The electrode body 220 is also formed with a positive electrode connection part 221 where no positive electrode active material layer is formed and the positive electrode current collector is exposed. The positive electrode connection part 221 is a rectangular positive electrode end part that protrudes upward from a part of the positive electrode. The electrode body 220 is also formed with a negative electrode connection part 222 where no negative electrode active material layer is formed and the negative electrode current collector is exposed. The negative electrode connection part 222 is a rectangular negative electrode end part that protrudes upward from a part of the negative electrode so as not to overlap with the positive electrode connection part 221.

[0024] The separator is, for example, a porous resin sheet having a required heat resistance. The separator is interposed between the positive electrode and the negative electrode to insulate the positive electrode from the negative electrode. The cell 201 is configured so that charge carriers (lithium ions in the case of a lithium ion secondary battery) move between the positive electrode and the negative electrode through a plurality of fine holes formed in the separator. Note that any separator that can be used in a lithium ion secondary battery can be used without any particular limitation.

[0025] The positive and negative external terminals 230, 240 are fixed to the lid 212 via insulating seal members (not shown) provided on the upper and lower surfaces of the lid 212. The positive and negative external terminals 230, 240 have, for example, rectangular plate-shaped bases 231, 241, and shafts 232, 242 extending downwardly inserted into the through-holes 212a of the lid 212 and the through-holes 251a, 261a of the positive and negative current collecting terminals 250, 260, and the tips of the shafts 232, 242 are crimped. That is, the positive and negative external terminals 230, 240 are arranged such that the bases 231, 241, which are parts of the terminals, are disposed outside the battery case 210, and the shafts 232, 242, which are the remaining parts of the terminals, extend from the outside to the inside of the battery case 210. In this manner, at least a portion of each of the positive and negative external terminals 230, 240 is disposed outside the battery case 210. The positive and negative external terminals 230, 240 are electrically connected to the electrode assembly 220 via the positive and negative current collecting terminals 250, 260.

[0026] The positive and negative electrode current collector terminals 250, 260 are plate-shaped conductive members. The positive and negative electrode current collector terminals 250, 260 are disposed inside the battery case 210. The positive and negative electrode current collector terminals 250, 260 have base portions 251, 261 extending toward the outside in the width direction of the cell 201, and lead portions 252, 262 extending toward the inside in the width direction of the cell 201 from the tips of the ends of the base portions 251, 261 bent downward. The base portion 251 of the positive electrode current collector terminal 250 is joined to the positive electrode external terminal 230 by crimping or the like. The lead portion 252 of the positive electrode current collector terminal 250 is joined to the positive electrode connection portion 221 of the electrode body 220 by welding. The base portion 261 of the negative electrode current collector terminal 260 is joined to the negative electrode external terminal 240 by crimping or the like. The lead portion 262 of the negative electrode current collecting terminal 260 is joined to the negative electrode connecting portion 222 of the electrode body 220 by welding.

[0027] The positive electrode external terminal 230 and the positive electrode current collector terminal 250 are made of, for example, a metal material mainly made of aluminum. Thus, the positive electrode external terminal 230 and the positive electrode current collector terminal 250 may be made of the same metal material, but are not particularly limited, and may be made of different metal materials. As for the metal material, any material that can be used for the positive electrode external terminal 230 and the positive electrode current collector terminal 250 can be used without any particular limitation. The negative electrode external terminal 240 and the negative electrode current collector terminal 260 are made of, for example, a metal material mainly made of copper. Thus, the negative electrode external terminal 240 and the negative electrode current collector terminal 260 may be made of the same metal material, but are not particularly limited, and may be made of different metal materials. As for the metal material, any material that can be used for the negative electrode external terminal 240 and the negative electrode current collector terminal 260 can be used without any particular limitation.

[0028] At least one of the positive and negative current collector terminals 250, 260 has a fusion part 253 formed thereon that can be fused at a temperature equal to or higher than the fusion temperature. In this embodiment, the fusion part 253 is formed only in the positive current collector terminal 250. However, the fusion part 253 may be formed in each of the positive current collector terminal 250 and the negative current collector terminal 260, or may be formed only in the negative current collector terminal 260. Each cell 201 constituting the battery 200 has the same configuration. That is, each cell 201 constituting the battery 200 includes a positive current collector terminal 250 in which the fusion part 253 is formed.

[0029] In the positive electrode current collector terminal 250, the fusion portion 253 is formed in the lead portion 252. Specifically, the fusion portion 253 is formed between the boundary between the base portion 251 and the lead portion 252 and the joint portion 252a between the lead portion 252 and the electrode body 220. The fusion portion 253 is formed in the lead portion 252 so as to have a smaller cross-sectional area than the other portions except the fusion portion 253. Since the fusion portion 253 has a smaller current conduction area than the other portions, the electrical resistance of the fusion portion 253 may be larger than the other portions. Therefore, when an overcurrent flows through the cell 201, the amount of heat generated by the fusion portion 253 may be relatively large, and the amount of heat dissipated by the fusion portion 253 may be relatively small. Therefore, when an overcurrent flows through the cell 201, the temperature change ΔT (temperature rise) of the fusion portion 253 may be larger than the other portions. As long as the cross-sectional area described above can be ensured, there is no particular limitation on the shape of the fusing portion 253. The fusing portion 253 shown in FIG. 2 is formed by providing notches 254 at both ends of the lead portion 252 in the width direction.

[0030] The temperature sensor 410 is an example of a temperature detection unit that detects a temperature T1 of a current collecting terminal (positive current collecting terminal 250 in this embodiment) on which the fusion portion 253 is formed. The temperature sensor 410 is attached to a surface of the cell 201 including the positive current collecting terminal 250. Specifically, the temperature sensor 410 is attached to an upper surface of the lid 212 by an attachment means such as an adhesive so as to be disposed in the vicinity of the positive current collecting terminal 250 on which the fusion portion 253 is formed. The temperature sensor 410 detects the temperature of the attached cell 201 as the temperature T1 of the positive current collecting terminal 250. For the temperature sensor 410, a temperature sensing element such as a thermistor can be used, for example.

[0031] 1, in this embodiment, one temperature sensor 410 is attached to one of the multiple cells 201 constituting the battery 200. The temperature sensor 410 is preferably attached to the cell 201 that generates the largest amount of heat among the multiple cells 201 constituting the battery 200. However, as described above, only one temperature sensor 410 may be provided for one battery 200, or one may be provided for each of the multiple cells 201. The temperature sensor 410 outputs a detection result of the detected temperature T1 to the ECU 300.

[0032] The current sensor 420 is an example of a current detection unit that detects a current I input to and output from the battery 200 including the cell 201. The current sensor 420 is attached to a current path of the battery 200. The current sensor 420 outputs the detection result of the detected current I to the ECU 300.

[0033] The monitoring unit including the temperature sensor 410 and the current sensor 420 may further include other sensors for detecting the state of the battery 200, such as a voltage sensor for detecting the voltage of the cell 201 of the battery 200. Such a monitoring unit outputs the detection result of the state of the battery 200 to the ECU 300. The monitoring unit may be a BMS (Battery Management System) having a SOC (State Of Charge) estimation function, a SOH (State of Health) estimation function, a cell voltage equalization function, a diagnosis function, and a communication function in addition to the above sensor function. The ECU 300 can obtain the state of the battery 200 (for example, the temperature T1, the current I, the voltage, the SOC, and the internal resistance) based on the output of the monitoring unit. The battery pack 10 may also have cooling means such as a fan for blowing air to cool the battery 200 and a cooling device for supplying a refrigerant for cooling the battery 200.

[0034] The ECU 300 has a function of controlling the operation of each component of the battery pack 10 as a whole. The ECU 300 includes a processor 310, a random access memory (RAM) 320, and a storage device 330. For example, a central processing unit (CPU) can be used as the processor 310. The RAM 320 functions as a working memory that temporarily stores data processed by the processor 310. The storage device 330 is configured to be able to save stored information. The storage device 330 includes, for example, a read only memory (ROM) and a rewritable non-volatile memory. In addition to the program, the storage device 330 stores information used in the program (for example, heat capacity C, electrical resistance R, thermal resistance θ, temperature change threshold ΔTthr, and various parameters). In this embodiment, the processor 310 executes the program stored in the storage device 330, thereby executing various controls in the ECU 300. However, the various controls in the ECU 300 are not limited to being executed by software, and can also be executed by dedicated hardware (electronic circuit). The number of processors included in ECU 300 is arbitrary, and a processor may be provided for each predetermined control.

[0035] The ECU 300 adjusts the battery power, for example, by controlling the PCU 12. When the ignition switch 500 of the vehicle 100 is in the ON state, the SMR 13 is in the ON state, and power is supplied from the battery 200 to the PCU 12. Therefore, when the ignition switch 500 of the vehicle 100 is in the ON state, the ECU 300 controls the PCU 12 to allow the vehicle 100 to run. On the other hand, when the ignition switch 500 is in the OFF state, the SMR 13 is in the OFF state, and power is no longer supplied from the battery 200 to the PCU 12. Therefore, when the ignition switch 500 is in the OFF state, the vehicle system is in a stopped state (for example, a sleep state).

[0036] As described above, since the fusing portion 253 is configured to locally concentrate heat when an overcurrent flows through the cell 201, the temperature change ΔT may become large. Therefore, the ECU 300 estimates the temperature change ΔT of the fusing portion 253 based on the detection results of the temperature T1 and the current I, and when the estimated temperature change ΔT of the fusing portion 253 is equal to or greater than a predetermined temperature change threshold ΔTthr, the ECU 300 restricts the input / output of the battery 200 as a control for suppressing a temperature rise of the battery 200. In other words, the ECU 300 performs temperature control for suppressing a temperature rise of the battery 200 when it is predicted from the estimated temperature change ΔT of the fusing portion 253 that the fusing portion 253 will melt.

[0037] The flow of the temperature control process executed by the ECU 300 will be described with reference to Fig. 3. Fig. 3 is a flowchart showing the temperature control process of the battery pack 10 according to the first embodiment. The process shown in the flowchart of Fig. 3 is repeatedly executed at a predetermined cycle while the ignition switch 500 of the vehicle 100 on which the battery pack 10 is mounted is in the ON state, for example.

[0038] 3, step S1 is a process of estimating temperature change ΔT of fusing portion 253 based on the detection results of temperature T1 and current I. In step S1, first, ECU 300 acquires the detection result of temperature T1 from temperature sensor 410, and acquires the detection result of current I from current sensor 420. Then, ECU 300 calculates temperature change ΔT of fusing portion 253 based on the acquired detection results of temperature T1 and current I.

[0039] For example, the temperature change ΔT of the fusion portion 253 can be calculated by subtracting the amount of heat dissipated by the fusion portion 253 from the amount of heat generated by the fusion portion 253, and multiplying the result by the heat capacity C. Specifically, the temperature change ΔT of the fusion portion 253 is calculated by the following formula (1). ΔT=C×{I 2R -(T1-T2) / θ} Equation (1) Here, ΔT is the temperature change of the fusion portion 253, C is the heat capacity of the positive current collecting terminal 250, I is the current, R is the electrical resistance of the fusion portion 253, θ is the thermal resistance of the fusion portion 253, T1 is the temperature of the positive current collecting terminal 250, and T2 is the cooling temperature at which the positive current collecting terminal 250 is cooled. The heat capacity C, the electrical resistance R, and the thermal resistance θ are each constants that are previously set by experiment or the like. Also, "I 2R " represents the amount of heat generated by fusion portion 253, and "(T1-T2) / θ" represents the amount of heat dissipated by fusion portion 253. Furthermore, cooling temperature T2 is the temperature of the air that cools battery 200, the temperature of cell 201 adjacent to cell 201 including positive electrode current collecting terminal 250 that is the detection target of temperature sensor 410, or the temperature of the refrigerant that cools battery 200.

[0040] Next, in step S2, the estimated temperature change ΔT of the fusion part 253 is compared with a predetermined temperature change threshold ΔT thr In step S2, ECU 300 compares the temperature change ΔT estimated in step S1 with the temperature change threshold ΔTthr read from storage device 330 to determine which is larger. In this way, ECU 300 predicts whether fusing portion 253 will melt. It is preferable to use a temperature change threshold ΔTthr of 30° C. or lower (for example, a temperature that is equal to or lower than the heat resistance temperature of a resin part disposed in the vicinity of positive collector terminal 250 inside battery case 210).

[0041] When ECU 300 determines that temperature change ΔT is equal to or greater than temperature change threshold ΔTthr (step S2; YES), melting of melting portion 253 is predicted, and therefore the process proceeds to step S3. Step S3 is a process of restricting input / output of battery 200. In step S3, ECU 300 restricts power input / output to / from battery 200 so that temperature change ΔT is less than temperature change threshold ΔTthr. This suppresses melting of melting portion 253, allowing vehicle 100 to run continuously.

[0042] On the other hand, in step S2, when ECU 300 determines that temperature change ΔT is not equal to or greater than temperature change threshold value ΔTthr (step S2; NO), it is predicted that fusing portion 253 will not melt, and therefore returns the process to step S1 without restricting input / output of battery 200. This allows vehicle 100 to continue traveling.

[0043] Thus, in this embodiment, ECU 300 restricts input / output of battery 200 so that the temperature of fusion part 253 does not exceed the fusion temperature. Therefore, according to this embodiment, the current collector terminal (positive current collector terminal 250 in this embodiment) on which fusion part 253 is formed can be protected from heat generated due to a temperature rise in a normal use state of battery pack 10, and fusion of fusion part 253 can be suppressed. As a result, the current path is not interrupted due to fusion of fusion part 253, and it is possible to prevent vehicle 100 from becoming unable to run.

[0044] The present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit of the present invention. For example, in the above-described embodiment, the battery pack 10 and the temperature control method for the battery pack 10 have been described by taking the input / output restriction of the battery 200 as an example of control for suppressing a temperature rise of the battery 200. However, the control for suppressing a temperature rise of the battery 200 is not limited to the input / output restriction of the battery 200, and may be cooling of the battery 200. When cooling the battery 200, the ECU 300 may increase the rotation speed of a fan that blows air to cool the battery 200, may increase the supply amount of the coolant that cools the battery 200, or may combine these. [Explanation of symbols]

[0045] 10 Battery pack 11 MG 12 PCU 13 SMR 14 Power transmission gear 15 Drive wheel 100 vehicles 200 Battery 201 Cell 210 Battery case 211 Case body 212 Lid 212a Through hole 220 Electrode body 221 Positive electrode connection part 222 Negative electrode connection part 230 Positive external terminal 231, 241 Base portion 232, 242 Shaft portion 240 Negative external terminal 250 Positive current collector terminal 260 Negative current collector terminal 251, 261 Base portion 251a, 261a Through hole 252, 262 Lead portion 252a Joint portion 253 Melting portion 254 Notch portion 310 processor; 320 RAM; 330 storage device 410 Temperature Sensor 420 Current Sensor 500 Ignition Switch

Claims

1. At least one cell including a battery case, an electrode assembly housed inside the battery case, an external terminal at least a part of which is disposed outside the battery case, and a current collecting terminal having a fusing portion formed therein that can be blown at a temperature equal to or higher than a fusing temperature and electrically connecting the electrode assembly to the external terminal; a temperature detection unit for detecting a temperature of the current collecting terminal; a current detection unit that detects a current input to and output from a battery including the cell; a temperature control device that estimates a temperature change of the fusion portion based on a detection result of the temperature of the current collecting terminal detected by the temperature detection unit and the current detected by the current detection unit, and limits input / output of the battery or cools the battery when the estimated temperature change of the fusion portion is equal to or greater than a predetermined temperature change threshold; A battery pack having

2. The temperature change of the fusion portion is ΔT=C×{I ２Ｒ - (T1-T2) / θ} 2. The battery pack according to claim 1, wherein ΔT is a temperature change of the fusion portion, C is a heat capacity of the current collecting terminal, I is the current, R is an electrical resistance of the fusion portion, θ is a thermal resistance of the fusion portion, T1 is a temperature of the current collecting terminal, and T2 is a cooling temperature at which the current collecting terminal is cooled.

3. a step of estimating a temperature change of a fusion part based on a detection result of a temperature of the current collecting terminal of at least one cell including a battery case, an electrode body housed inside the battery case, an external terminal at least a part of which is disposed outside the battery case, and a current collecting terminal in which a fusion part that can be fused at a temperature equal to or higher than a fusion temperature is formed and which electrically connects the electrode body to the external terminal, and a current input / output to / from a battery including the cell; limiting input / output of the battery or cooling the battery when the estimated temperature change of the fusion portion is equal to or greater than a predetermined temperature change threshold; A temperature control method for a battery pack comprising:

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