Resistance measuring device and inspection system

Abstract

To provide a resistance measuring device in which internal resistance measurement accuracy of a battery is improved.SOLUTION: A resistance measuring device of a secondary battery that is connected to a plate-like electrical derivation member being either one member of lead for extracting electricity from inside the battery and a bus bar 61 connected to the lead, and measures resistance of the secondary battery comprises: a current application terminal 31 that is connected to the secondary battery; a voltage detection terminal 41 that is connected to the secondary battery; and a measuring instrument that measures resistance of the secondary battery on the basis of voltage output from the voltage detection terminal 41. The current application terminal 31 contacts with the electrical derivation member using surface contact of a first contact part 61b on a principal surface of the electrical derivation member; the voltage detection terminal 41 contacts with the electrical derivation member using a second contact part 61c on the electrical derivation member; and the first contact part 61b is positioned closer to a secondary battery side than the second contact part 61c on an electrical conduction path from the second contact part 61c to the secondary battery.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a resistance measuring device and an inspection system for measuring the resistance of a secondary battery. [Background technology]

[0002] Conventionally, there has been known a battery with a voltage detection terminal in which an insulating member is sandwiched between the bus bar and the voltage detection terminal to suppress the flow of current between the bus bar and the voltage detection terminal (Patent Document 1). In the battery of Patent Document 1, the positive and negative terminals are male threads, and the bus bar, washer (insulating member), and voltage detection terminal are each plate-like members with holes formed according to the diameter of the male thread of the positive and negative terminals, and are fixed by stacking the bus bar, washer (insulating member), and voltage detection terminal in this order and then screwing them together. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-44549 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the battery described in Patent Document 1 has a problem in that the resistance in the axial direction of the male threads of the positive and negative terminals varies greatly, and the voltage drop at the measurement point varies, resulting in low accuracy in measuring the battery's internal resistance.

[0005] An object of the present invention is to provide a resistance measuring device that improves the accuracy of measuring the internal resistance of a battery. [Means for solving the problem]

[0006] The present invention solves the above problem by connecting to a plate-shaped electrical lead-out member, which is either a lead or a bus bar, to measure the resistance of a secondary battery, the current application terminal making surface contact with the electrical lead-out member at a first contact portion on a main surface of the electrical lead-out member, and the voltage detection terminal making surface contact with the electrical lead-out member at a second contact portion on the electrical lead-out member, and the first contact portion being located closer to the secondary battery than the second contact portion on the electrical conduction path from the second contact portion to the secondary battery. [Effects of the Invention]

[0007] According to the present invention, it is possible to reduce variations in the resistance between the electrical lead-out member and the current application terminal, thereby improving the accuracy of measuring the internal resistance of the battery. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram of a resistance measuring device according to this embodiment. [Figure 2] FIG. 2(a) is a perspective view of a secondary battery measured by a resistance measuring device, and FIG. 2(b) is a partial perspective view of leads and bus bars included in the secondary battery. [Figure 3] FIG. 3(a) is a plan view of a substrate included in the resistance measuring device, and FIG. 3(b) is a perspective view of the battery pack 6. As shown in FIG. [Figure 4] FIG. 4(a) is a cross-sectional view of the connection portion between the terminal of the resistance measuring device and the terminal of the secondary battery, and FIGS. 4(b-1, b-2) are plan views of the terminal of the resistance measuring device. [Figure 5] Figure 5(a-1) is a conceptual diagram of the terminal surface in this embodiment, Figure 5(a-2) is a conceptual diagram of the terminal surface in a modified example of this embodiment, and Figures 5(b) and 5(c) are conceptual diagrams of the terminal surface in a reference example. [Figure 6] 6(a) to 6(c) are conceptual diagrams for explaining the connection configuration of the current application terminals, voltage detection terminals, current sources, and voltmeters. [Figure 7] FIG. 7 is a conceptual diagram of the inspection system according to this embodiment. [Figure 8]FIG. 8 is a side view of the connection portion between the terminal of a resistance measuring device and the terminal of a secondary battery according to another embodiment of the present invention. [Figure 9] FIG. 9 is a side view of the connection portion between the terminal of a resistance measuring device and the terminal of a secondary battery according to another embodiment of the present invention. [Figure 10] FIG. 10 is a side view of the connection portion between the terminal of a resistance measuring device and the terminal of a secondary battery according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] First Embodiment The resistance measuring device for a secondary battery according to the present invention will be described with reference to the drawings. Fig. 1 is a block diagram of the resistance measuring device according to this embodiment, Fig. 2(a) is a perspective view of a secondary battery measured by the resistance measuring device, and Fig. 2(b) is a partial perspective view of leads and bus bars included in the secondary battery.

[0010] 1, resistance measuring device 1 includes measuring instrument 10, voltage measuring circuit 20, current application terminals 31 and 32, and voltage detection terminals 41 and 42. Resistance measuring device 1 is a device that measures the internal resistance of a large-capacity battery (module) for an electric vehicle, hybrid vehicle, or the like. Resistance measuring device 1 is a device that is useful, for example, for measuring the state of deterioration of battery performance, and is particularly used for detecting (measuring) electrolyte resistance in a very small resistance range.

[0011] Measuring instrument 10 applies current to the secondary battery from P-pole current application terminal 31, and passes current from P-pole current application terminal 31 through the secondary battery to N-pole current application terminal 32. While current is being applied to the secondary battery (battery cell), measuring instrument 10 measures the terminal voltage of the secondary battery using voltage measurement circuit 20. Measuring instrument 10 then measures the internal resistance of the secondary battery based on the detected voltage. Note that the internal resistance can be measured by measuring instrument 10 using various measurement methods, such as an AC impedance measurement method.

[0012] Voltage measurement circuit 20 is a circuit for measuring the terminal voltage of a secondary battery, and includes current source 21 and voltmeter 22. Current source 21 is connected between current application terminal 31 and current application terminal 32, and voltmeter 22 is connected between voltage detection terminal 41 and voltage detection terminal 42. Current source 21 outputs a current in response to a control command from measuring instrument 10. Voltmeter 22 outputs detected voltage data to measuring instrument 10.

[0013] Current application terminals 31 and 32 are conductive members connected to the secondary battery and input and output current from current source 21. Voltage detection terminals 41 and 42 are conductive members connected to the secondary battery and detect the output voltage of the secondary battery. Current application terminal 31 and voltage detection terminal 41 correspond to the resistance measurement terminals on the P-pole side, and current application terminal 32 and voltage detection terminal 42 correspond to the resistance measurement terminals on the N-pole side. The structure of each terminal and the structure of the connection portion with the secondary battery will be described later.

[0014] FIG. 2(a) shows a perspective view of the battery 5 under test in the resistance measuring device 1. The secondary battery 2 is, for example, a lithium-ion secondary battery. The secondary battery 5 includes a battery case, multiple secondary batteries, tab leads, and bus bars. The battery case is a metal case that houses the secondary batteries. The secondary battery is composed of a power generating element formed by laminating a positive electrode layer, a negative electrode layer, and a separator and filling it with an electrolyte, and an exterior member that houses and seals the tab leads connected to the positive and negative electrode layers. While a detailed description of the materials contained in the secondary battery and its structure is omitted, well-known battery materials and structures can be applied to the secondary battery. Multiple secondary batteries are connected in series or parallel and housed in the battery case.

[0015] The tab leads (leads) of the secondary battery are made of plate-shaped metal members so that electricity can be extracted from inside the secondary battery. The tips of the tab leads are connected to bus bars. The ends of the bus bars serve as the positive electrode terminal (P terminal), intermediate terminal, and negative electrode terminal (N terminal) of the secondary battery 2, and are provided with screw holes for bolt fastening. The bus bars are formed by bending and extending plate-shaped members from the tips of the tab leads toward the terminals (P terminal, N terminal, intermediate terminal). The terminals (P terminal, N terminal, intermediate terminal) of the secondary battery 2 are not limited to the ends of the bus bars, but may also be the tips of the tab leads. In other words, the secondary battery 2 may be configured so that electricity can be extracted directly from the tab leads without going through the bus bars. The tab leads and bus bars correspond to the "electrical lead-out members" for extracting electricity from inside the battery in this invention.

[0016] FIG. 2(b) is a perspective view illustrating only tab leads 51-53 and bus bars 61-63 of the secondary battery 5 shown in FIG. 2(a). The secondary battery 5 is made up of two batteries connected in series. Tab lead 51 is a terminal for the P pole of one of the two batteries, tab lead 52 is a terminal for the P pole of the other battery, and tab lead 52 is a terminal for the N pole of the other battery. Note that in FIG. 2(b), the tab lead that serves as the terminal for the N pole of one battery is omitted, and the tab lead for the N pole of one battery is connected to bus bar 62.

[0017] Busbar 61 is a busbar for the P pole and is connected to tab lead 51. Busbar 62 is a busbar for an intermediate terminal and is connected to tab lead 52 and a tab lead for the N pole of one of the batteries. Busbar 63 is a busbar for the N pole and is connected to tab lead 53. Busbars 61 to 63 have terminal surfaces formed by bending metal members extending in the z-axis direction in an orthogonal direction. The terminal surfaces of busbars 61 and 62 extend from the bent portion in the positive direction of the y-axis, and the terminal surface of busbar 63 extends from the bent portion in the negative direction of the y-axis. The dotted arrows in FIG. 2(b) indicate the conduction direction of current applied from resistance measuring device 1 to secondary battery 5.

[0018] Next, the connection structure between the terminals of the resistance measuring device 1 and the terminals of the secondary battery 5 will be described with reference to Fig. 3 and Fig. 4. Fig. 3(a) is a plan view of the substrate 70 included in the resistance measuring device 1. Fig. 3(b) is a perspective view of the battery pack 6. Fig. 4(a) is a cross-sectional view of the connection portion between the terminals of the resistance measuring device 1 and the terminals of the secondary battery 5, and Fig. 4(b) is a plan view of the terminals of the resistance measuring device 1.

[0019] A substrate 70 is provided inside the resistance measuring device 1, and mounted on the substrate 70 are a voltage measurement circuit 20, current application terminals 31 and 32, voltage detection terminals 41 and 42, intermediate electrode terminals 33 and 34, and a terminal box 35. A terminal box 35 for connecting to a current source 21 is also mounted on the substrate 70. The current application terminal 31 and other terminals are connected to the voltage measurement circuit 20 and the terminal box 35 by wiring within the substrate 70. The current application terminal 31 and other terminals are arranged in two rows and three columns to match the terminal arrangement of the battery pack 6, with the terminals in the first row and the terminals in the second row being connected to the terminals in the first and second rows of the battery pack 6. The P-pole terminal, consisting of the current application terminal 31 and the voltage detection terminal 41, and the N-pole terminal, consisting of the current application terminal 32 and the voltage detection terminal 42, have common dimensions (standardized). The substrate 70, on which various terminals such as the current application terminal 31 are mounted, is housed in a case (not shown), and the various terminals such as the current application terminal 31 are exposed from the case by, for example, a resin socket so that they can be connected to the terminals of the battery pack 6. When the terminals of the battery pack 6 are fitted into the socket, the resistance measuring device 1 and the battery pack 6 are electrically connected.

[0020] As shown in FIG. 3(b), the battery pack 6 is configured by packaging two secondary batteries 5. In the example of FIG. 3(b), the secondary batteries 5 are arranged in two layers, but three or more layers are also possible. Mass-produced cell modules, such as lithium-ion batteries for EVs, often have a configuration in which a predetermined number of secondary batteries are packaged as a battery pack (two layers of two series-connected cells). Furthermore, to reduce costs, the terminals of the battery pack 6 are typically standardized (commonly sized). In this embodiment, the terminals mounted on the substrate 70 are also standardized to match the battery specifications, thereby reducing device manufacturing costs. Specifically, the terminals on the substrate 70 are manufactured on the same substrate 70 using a printed circuit board manufacturing method to match the terminal layout of the battery pack 6. This reduces the cost of mass-produced resistance measurement devices 1. Furthermore, in the example of FIG. 3(a), a bus bar 36 that connects the upper and lower batteries in series is formed on the substrate 70. This simplifies wiring materials and the wiring work during measurement.

[0021] Next, with reference to FIG. 4(a), the structure of the connection portion between the terminals on the P-pole side will be described. The structure of the connection portion between the terminals on the N-pole side is the same as that on the P-pole side, and therefore will not be described here. The busbar 61 extends along the xz plane and is bent at a bend 61a so that the busbar extension direction changes from the z-axis direction to the y-axis direction, thereby forming the end of the busbar 61 as a terminal for the secondary battery 5. The end of the busbar 61 facing the current application terminal 31 and the voltage detection terminal 41 forms the terminal surface. The terminal surface forms the main surface of the busbar 61. The terminal surface has a first contact portion 61b that connects with the current application terminal 31 and a second contact portion 61c that connects with the voltage detection terminal 41. The first contact portion 61b and the second contact portion 61c are spaced a certain distance apart on the terminal surface, with the first contact portion 61b located at the bend 61a and the second contact portion 61c located away from the bend 61a. The first contact portion 61b does not necessarily have to be located at the bent portion 61a, but may be located closer to the bent portion 61a than the second contact portion 61c.

[0022] When the terminal portion of the secondary battery 5 is fitted into the socket of the resistance measuring device 1, the current application terminal 31 comes into surface contact with the bus bar 61 at the first connection portion 61b, and the voltage detection terminal 41 comes into surface contact with the bus bar 61 at the second connection portion 61c.

[0023] Next, with reference to Fig. 4(b-1, b-2), the terminal surfaces of the current applying terminals 31, 32 and the voltage detecting terminals 41, 42 will be described. Fig. 4(b-1) is a plan view of the terminal surfaces of the current applying terminal 31 and the voltage detecting terminal 41, which are terminals on the P-pole side, and Fig. 4(b-2) is a plan view of the terminal surfaces of the current applying terminal 32 and the voltage detecting terminal 42, which are terminals on the N-pole side.

[0024] 2, the busbar 61 on the P-pole side is bent so that the busbar extension direction changes from the z-axis direction to the positive direction of the y-axis, and therefore, on the xy plane, the terminal surface 31a of the current applying terminal 31 is located lower (on the negative side of the y-axis) than the terminal surface 41a of the voltage detecting terminal 41 (see FIG. 4(b-1)). On the other hand, the busbar 63 on the N-pole side is bent so that the busbar extension direction changes from the z-axis direction to the negative direction of the y-axis, and therefore, on the xy plane, the terminal surface 32a of the current applying terminal 32 is located higher (on the positive side of the y-axis) than the terminal surface 42a of the voltage detecting terminal 42 (see FIG. 4(b-2)).

[0025] When the terminal portion of secondary battery 5 is fitted into the socket of resistance measuring device 1 and current is applied from current application terminals 31 and 32 to bus bars 61 and 63, the direction of current flow on the P-pole side is the negative direction of the y-axis, and the direction of current flow on the N-pole side is the positive direction of the y-axis. The terminal surface of the resistance measurement terminal on the P-pole side of resistance measuring device 1 is divided into two on the same plane, forming terminal surface 31a of current application terminal 31 and terminal surface 41a of voltage detection terminal 41. Similarly, the terminal surface of the resistance measurement terminal on the N-pole side is divided into two on the same plane, forming terminal surface 32a of current application terminal 32 and terminal surface 42a of voltage detection terminal 42. Also, referring to FIG. 1 , current application terminal 31 and current application terminal 32 are connected by wiring via current source 21, and voltage detection terminal 41 and voltage detection terminal 42 are connected by wiring via voltmeter 22. That is, the resistance measurement terminals are electrically divided into two parts, one for applying current and one for detecting voltage, on the P-pole side and the other for detecting voltage, and are arranged on the side facing bus bars 61, 63. In other words, current application terminals 31, 32 and voltage detection terminals 41, 42 are constantly separated within the contact surfaces of bus bars 61, 63. This ensures insulation between the terminals on the resistance measurement device 1 side, even if no insulating material is provided between current application terminals 31, 32 and voltage detection terminals 41, 42.

[0026] Because the measurement current applied to the secondary battery 5 from the current application terminals 31 and 32 has the property of flowing to the opposite electrode of the secondary battery, the measurement current does not flow through the contact surfaces of the voltage detection terminals 41 and 42, which are in contact at the position farthest from the secondary battery along the electrical conduction path of the secondary battery 5. In other words, the voltage detection terminals 41 and 42 are configured not to electrically interfere with the measurement current applied to the secondary battery 5 from the current application terminals 31 and 32. Therefore, the voltage signal used to detect the voltage of the secondary battery 5 does not include variations in the electrode current resistance of the bus bars 61 and 63 and variations in the surface contact resistance at the contact points between the terminal surfaces of the voltage detection terminals 41 and 42 and the second contact portions. This improves the accuracy of measuring the internal resistance of the battery.

[0027] The shape of the terminal surfaces of the current applying terminals 31 and 32 will be described with reference to Fig. 5. Fig. 5(a-1, 5-2) is a conceptual diagram for explaining the positional relationship between the ends of the bus bars 61 and 63, the terminal surfaces 31a and 32a of the current applying terminals 31 and 32, and the terminal surfaces 41a and 42a of the voltage detecting terminals 41 and 42. Fig. 5(a-1) is a conceptual diagram of the terminal surfaces in this embodiment, and Fig. 5(a-2) is a conceptual diagram of the terminal surfaces in a modified example of this embodiment. Figs. 5(b) and 5(c) are conceptual diagrams of the terminal surfaces in a reference example. Note that the shape and arrangement of the terminal surfaces on the N-pole side are the same as those on the P-pole side, and therefore will not be described here.

[0028] As shown in FIG. 5(a-1), the terminal surface 31a of the current application terminal 31 is formed in a rectangular shape having short and long sides. The terminal surface 31a is in contact with the first contact portion 61b of the bus bar 61 so that the short side of the terminal surface 31a is the side along the conduction direction of the measurement current and the long side of the terminal surface 31a is the side along the direction perpendicular to the conduction direction of the measurement current. The direction along the long side of the terminal surface 31a is perpendicular to the conduction direction of the measurement current, and the direction along the short side of the terminal surface 31a is the direction along the conduction direction of the measurement current. The terminal surface 31a is in contact with the main surface of the bus bar 61 so that the longitudinal direction of the terminal surface 31a is perpendicular to the conduction direction of the measurement current. The angle between the longitudinal direction of the terminal surface 31a and the conduction direction of the measurement current is defined as θ e In this case, θ e = 90 (deg). The area of ​​the terminal surface 31a is designed to be large enough to meet the current carrying capacity of the measurement current. The area of ​​the terminal surface 31a affects the resistance between the terminal surface 31a and the first contact portion 61b, so to lower this resistance, it is best to make it as large as possible, but as the area becomes larger, the amount of deviation of the measurement point increases. On the other hand, if the area of ​​the terminal surface 31a becomes too small, the amount of heat generated when the measurement current is conducted increases. In this embodiment, the area of ​​the terminal surface 31a is set to a current carrying area that does not generate excessive heat at the allowable value of the measurement current.

[0029] The terminal surface 41a of the voltage detection terminal 41 is in contact with the second contact portion 61c of the busbar 61. The terminal surface 41a is rectangular, and the area of ​​the terminal surface 41a is larger than the area of ​​the terminal surface 31a. The first contact portion 61b is located closer to the battery than the second contact portion 61c on the electrical conduction path from the second contact portion 61c to the secondary battery 5. The first contact portion 61b corresponds to the current flow range of the measurement current, and the second contact portion 61c corresponds to the detection range for detecting the voltage of the battery cell. Therefore, the current flow range of the measurement current is located farther from the tip of the busbar 61 on the main surface of the busbar 61, and the detection range is located closer to the tip of the busbar 61 on the main surface of the busbar 61.

[0030] Here, the magnitude of the measured current is I, and the resistance of the electrode material is R t The battery voltage of the secondary battery 5 is V c When the measurement current (I) is applied to the secondary battery 5, the measurement current (I) and the resistance (R t ) is generated. This voltage drop is equal to the detection voltage (V c ) and becomes a detection error of the battery voltage, and its magnitude is V=I×R t ×2 (PN both poles). In this embodiment, the conduction path of the measurement current does not include the electrode member resistance formed between the terminal surfaces of the voltage detection terminals 41, 42 and the second contact portion 61c, but does include the electrode member resistance formed between the terminal surfaces of the current application terminals 31, 32 and the first contact portion 61b. Therefore, the electrode member resistance (R t ) does not include a resistance component formed between the terminal surfaces of the current applying terminals 31, 32 and the second contact portion 61c, so that it is possible to suppress variations in contact resistance and voltage drop in the terminal portion.

[0031] Next, the position of the measurement current application point will be described with reference to FIG. 5. In FIG. 5, W i indicates the length of the long side of the terminal surface 31a, and L tindicates the length of the short side of the terminal surface 31a. When the terminal surfaces 31a and 32a of the current application terminals 31 and 32 contact the first contact portion 61b, the surfaces do not necessarily contact cleanly, and the contact points may vary within the terminal surfaces 31a and 32a. In FIG. 5(a-1), points on the terminal surface 31a represent current application points. As shown in FIG. 5(b), in the reference example, the angle θ between the longitudinal direction of the terminal surface 31a and the conduction direction of the measurement current is e are 45(deg) and 0(deg).

[0032] For example, θ e = 45 (deg), that is, when the boundary line (boundary line on the terminal surface 31a) of the measurement current flowing from the current application terminal 31 toward the inside of the cell is inclined at 45 degrees to the direction of current flow, the change width dx of the application point of the measurement current is Wi × cos(θ e ) and the position of the current application point may fluctuate within the range of variation dx relative to the current conduction direction. e If =0 (deg), the change width dx of the measurement current application point is W i Therefore, the position of the current application point may vary within a range of variation dx with respect to the current conduction direction. e = 90 (deg) and the change width dx of the applied point of the measurement current is L t and Wi×cos(θ e ) and Wi. Therefore, in this embodiment, the fluctuation range of the current is t The length of the slit is kept within a range equivalent to the length of the slit.

[0033] In this embodiment, the longitudinal direction of the terminal surfaces 31a and 32a of the current application terminals 31 and 32 is perpendicular to the direction of conduction of the measurement current. This makes it possible to suppress fluctuations in the current application point in the direction of conduction of the measurement current even if the contact resistance distribution on the measurement target surface changes. Furthermore, it is possible to accurately measure the internal resistance of batteries that are connected by surface contact.

[0034] The shape of the terminal surfaces of the current applying terminals 31 and 32 in the modified example will be described with reference to Fig. 5(a-2) and Fig. 5(c). In the modified example, the longitudinal length W of the terminal surfaces 31a and 32a is i is the width direction length W of the bus bar 61 t The width direction of the bus bar 61 is a direction perpendicular to the extending direction of the bus bar 61. On the other hand, as shown in FIG. 5(c), in the reference example, the longitudinal length W of the terminal surfaces 31a and 32a is i is the width direction length W of the bus bar 61 t In the modified example, even if the contact positions of the terminal surfaces 31a and 32a of the current applying terminals 31 and 32 are displaced in the width direction of the bus bar 61, the contact in the width direction is maintained, and the contact area between the terminal surfaces 31a and 32a and the first contact portion 61b of the bus bar 61 is not insufficient. On the other hand, in the reference example, the longitudinal length W of the terminal surfaces 31a and 32a is i Therefore, when the terminal surfaces 31a, 32a of the current applying terminals 31, 32 are shifted in the width direction of the bus bar 61, the contact area between the terminal surfaces 31a, 32a and the first contact portion 61b of the bus bar 61 becomes small. When the contact area becomes small, the resistance increases, and the amount of heat generated increases. Furthermore, the increase in contact resistance may impede the flow of the measurement current, resulting in a large measurement error.

[0035] As described above, in this embodiment, the longitudinal length of the terminal surfaces 31a, 32a of the current applying terminals 31, 32 is longer than the widthwise length of the bus bars 61, 63. This maintains a predetermined contact area even if the contact positions of the current applying terminals 31, 32 are misaligned, thereby preventing heat generation problems on the contact surfaces. Furthermore, the internal resistance of batteries that are connected by surface contact can be measured with high accuracy.

[0036] 6, the wiring paths when measuring the internal resistance of the secondary battery 5 and the wiring paths when adjusting the charge capacity of the secondary battery 5 will be described. Figures 6(a) to 6(c) are conceptual diagrams for explaining the connection configuration of the current application terminals 31 and 32, the voltage detection terminals 41 and 42, the current sources 21a and 21b, and the voltmeter 22.

[0037] 6(a), when the resistance measuring device according to this embodiment is dedicated to measuring internal resistance, the current source 21a is an AC power source for measurement, and the current source 21a is connected to the current application terminal 31 and the current application terminal 32. The voltmeter 22 is connected to the voltage detection terminal 41 and the voltage detection terminal 42.

[0038] As shown in FIG. 6(b), when the resistance measurement device 1 according to this embodiment is used to measure internal resistance and adjust charge capacity, the resistance measurement device 1 includes switches 23a and 23b that switch the wiring paths connected to the voltage detection terminals 41 and 42. The current source 21b serves as both a measurement current source and a charge / discharge current source, and is a power supply that can switch between AC and DC, or a bipolar power supply. The current source 21b is connected to the current application terminals 31 and 32, and is connected to the voltage detection terminals 41 and 42 via the switches 23a and 23b. The voltmeter 22 is connected to the voltage detection terminals 41 and 42 via the switches 23a and 23b. When measuring internal resistance, the switches 23a and 23b are switched so that the voltage detection terminals 41 and 42 are electrically connected to the voltmeter 22. When adjusting the charge capacity, the switches 23a and 23b are switched so that the voltage detection terminal 41 and the voltage detection terminal 42 are electrically connected to the current source 21b.

[0039] When the resistance measurement device 1 according to this embodiment is used to measure internal resistance and adjust charge capacity, the wiring may be a wiring path as shown in FIG. 6(c). The resistance measurement device 1 includes a measurement current source 21c, a charge / discharge current source 21d, and switches 23c and 23d. The switch 23c switches between conduction and interruption in the wiring path from the current application terminal 31 to the current application terminal 32 via the current source 21c. The switch 23d switches between conduction and interruption in the wiring path from the voltage detection terminal 41 to the voltage detection terminal 42 via the current source 21c. When measuring internal resistance, the switch 23c is turned on and the switch 23d is turned off. When adjusting charge capacity, the switch 23c is turned off and the switch 23d is turned on.

[0040] The resistance measurement device 1 according to this embodiment has a connection terminal dedicated to internal resistance measurement and the basic configuration of a resistance measurement device. The terminals of the resistance measurement device 1 contact the bus bars 61 and 63 via surface contact, and the size and shape of the terminal surfaces 31a and 32a are specified to minimize the contact area and minimize resistance variation. For currents of approximately 10 A, such as the measurement current, the size of the terminal surfaces 31a and 32a can be small to suppress heat generation. However, the contact area is insufficient when charging or discharging a large current of approximately 100 A, such as for SOC adjustment. Therefore, in this embodiment, the current-carrying electrodes are switched between measurement and charging / discharging. As shown in FIG. 6(b), the voltage detection terminals 41 and 42, which are connected to the voltmeter 22 during internal resistance measurement, are connected to the current source 21b during charging / discharging, allowing the charging / discharging current to flow across almost the entire surface of the contact terminals. Furthermore, as shown in FIG. 6(c), a configuration is provided in which the internal resistance measurement circuit and the charging / discharging power source can be switched. The voltage detection terminals 41 and 42 are always in a connected state and can also be used to monitor the cell voltage during charging and discharging.

[0041] As described above, in this embodiment, when adjusting the charge capacity of a secondary battery, the current application terminals 31, 32 and the voltage detection terminals 41, 42 are electrically connected via wiring. This eliminates the need to change terminals when switching between internal resistance measurement and capacity adjustment. Therefore, when the resistance measurement device according to this embodiment is applied to a device that performs battery degradation diagnosis, it is possible to increase the degree of freedom in design and improve testing productivity.

[0042] Next, an example of how the resistance measuring device 1 of this embodiment is used will be described. FIG. 7 is a conceptual diagram of an inspection system equipped with the resistance measuring device 1. For example, the resistance measuring device 1 is used in the manufacturing (shipment) inspection process of secondary batteries 5 and the state of health (SOH) inspection process for reusing secondary batteries 5. In these processes, SOC adjustment and resistance measurement processes are performed. The inspection system 100 according to this embodiment includes the resistance measuring device 1 and a rack 101 that houses secondary batteries. Secondary batteries 5 are loaded into the inspection rack 101 manually or automatically using a robot arm. Current application terminals 31 and 32 and voltage detection terminals 41 and 42 are provided on the surface facing the insertion opening of the rack 101. When the secondary battery 5 is loaded into the rack 101, the terminals are electrically connected. The resistance measuring device 1 applies a measurement current from a current source 21 to the terminals to perform resistance measurements. At this time, the measurement current may be applied to each rack individually, or may be applied collectively to a predetermined number or all of the racks connected in series. The data on internal resistance measured at each test slot is used for deterioration diagnosis, and the state of the secondary battery 5 is diagnosed by referring to the predefined calibration characteristics of state of health (SOH) and resistance (HFR). The diagnosis result (SOH) is printed on a label on the corresponding battery under test, which is then sorted and sent to the next process; for example, batteries with a remaining health (SOH) that can be used for secondary purposes are reused or utilized as recycled resources.

[0043] As described above, the testing system 100 according to this embodiment includes a resistance measuring device 1 and a rack 101. The terminals of the resistance measuring device 1 have high reproducibility of the connection state, allowing for precise implementation of the four-terminal method. By utilizing these advantages in the testing system, automated testing can be easily performed, the testing process can be made more efficient, productivity can be maintained, and maintenance labor can be reduced. As a result, the cost of battery use can be reduced.

[0044] As described above, in this embodiment, the current applying terminals 31, 32 make surface-to-surface contact with the first contact portions 61b on the main surfaces of the electrical leading members, which are the tab leads 51-53 or the bus bars 61, 63, and the voltage detecting terminals 41, 42 make surface-to-surface contact with the electrical leading members, which are the tab leads 51-53 or the bus bars 61, 63. The first contact portions 61b make surface-to-surface contact with the electrical leading members, and the voltage detecting terminals 41, 42 make surface-to-surface contact with the electrical leading members at the second contact portions 61c on the electrical leading members. The first contact portions 61b are located closer to the battery cell than the second contact portions 61c on the electrical conduction path from the second contact portions 61c to the secondary battery 5 (battery cell). As a result, the measurement current does not flow through the second contact portions 61c, and therefore the voltage signal for detecting the voltage of the secondary battery 5 does not include variations in the electrode current-carrying resistance of the bus bars 61, 63 and variations in the surface contact resistance at the contact portions between the terminal surfaces of the voltage detecting terminals 41, 42 and the second contact portions. This allows for accurate measurement of the internal resistance of batteries that are connected to the main surfaces of the tab leads 51-53 or the bus bars 61, 63 through surface contact. That is, the variation in resistance between the electrical lead-out member and the current applying terminals 31 and 32 can be reduced, and the accuracy of measuring the internal resistance of the battery can be improved.

[0045] In this embodiment, the terminal surfaces 31a, 32a of the current applying terminals 31, 32 are rectangular with short and long sides, the short sides being along the direction of current flow to be measured, and the long sides being along the direction perpendicular to the current flow, and the areas of the terminal surfaces 31a, 32a are large enough to accommodate the current flow capacity of the current applying terminals 31, 32. This prevents overheating of the terminal surfaces, reduces variations in resistance between the electrical leading members and the current applying terminals 31, 32, and improves the accuracy of measuring the internal resistance of the battery.

[0046] In this embodiment, the electrical lead-out members, such as the tab leads 51-53 or the bus bars 61-63, have a bent portion 61a, and the current application terminals 31-32 contact the bent portion 61a. The optimal contact position of the current application terminals 31-32 on the contact surfaces of the tab leads 51-53 or the bus bars 61-63 is closest to the secondary battery 5 and perpendicular to the direction of the current flow. In practice, the terminals of the secondary battery 5 are surrounded by an insulating cover, limiting the contact position to the contact surface. However, a bent position within this range without interfering with the insulating cover provides the optimal application point for the current to be measured. This allows the current to be applied to the secondary battery 5 from an optimal position, minimizing the addition of bus bar resistance unrelated to the cell internal resistance, which is the target of measurement. As a result, the internal resistance of batteries that are connected by surface contact with the main surfaces of the tab leads 51-53 or the bus bars 61-63 can be accurately measured.

[0047] Second Embodiment Next, a resistance measuring device according to a second embodiment will be described. In the second embodiment, the structure of the terminal portions of the current applying terminals 31, 32 and the voltage detecting terminals 41, 42 is partially changed. Note that, except for the differences from the resistance measuring device according to the first embodiment in the points described below, the second embodiment has the same configuration as the first embodiment and operates or functions in the same way as the first embodiment, and the description of the first embodiment will be used as appropriate.

[0048] The structure of the connection portion between the P-pole terminals will be described with reference to Figure 8. Figure 8 is a side view of the connection portion between the terminals of the resistance measuring device 1 and the terminals of the secondary battery 5. Figure 8(a) shows the state when not in contact, Figure 8(b) shows the state when measuring internal resistance, and Figure 8(c) shows the state when adjusting the charge capacity. Note that the connection portion of the terminals has other members such as bolts for fastening the terminals together, but these other members are not shown in the side view of Figure 8 to avoid explanation. The same is true for Figures 9 and 10, which will be described later.

[0049] An elastic contact member 31b is fixed to the tip of the current application terminal 31. The elastic contact member 31b is a cantilevered metal leaf spring that has elastic force in the direction of contact with the bus bar 61 (the negative direction of the y-axis) and is electrically connected to the main body of the current application terminal 31. The elastic contact member 31b is a part of the current application terminal 31. The voltage detection terminal 41 extends in the direction of contact with the bus bar 61 and curves toward the space between the second contact portion 61c and the terminal surface 31a of the current application terminal 31, thereby forming a surface (terminal surface 41a) parallel to the second contact portion 61c and the terminal surface 31a. The voltage detection terminal 41 is formed by curving a plate-shaped metal. As shown in FIG. 8(a), when not in contact, the elastic contact member 31b is not in contact with the first contact portion 61b of the bus bar 61, and the voltage detection terminal 41 is not in contact with the second contact portion 61c or the terminal surface 31a of the current application terminal 31.

[0050] When the current application terminal 31 and the voltage detection terminal 41 are pushed in along the z-axis direction from the state shown in FIG. 8(a) and approach the bus bar 61, as shown in FIG. 8(b), the elastic contact member 31b elastically deforms and contacts the first contact portion 61b, and the terminal surface 41a of the voltage detection terminal 41 contacts the second contact portion 61c. As a result, the elastic force of the elastic contact member 31b presses the current application terminal 31 against the bus bar 61. Meanwhile, the rear surface of the terminal surface 41a of the voltage detection terminal 41 and the terminal surface 31a of the current application terminal 31 are separated and do not contact each other. The measurement current applied from the current application terminal 31 to the secondary battery 5 flows from the elastic contact member 31b through the first contact portion to the bus bar 61 (see arrow i in FIG. 8(b)). At this time, the measurement current does not flow through the second contact portion 61c. Therefore, the measurement current can be applied to the secondary battery 5 without electrically interfering with the voltage detection terminal 41.

[0051] When the current applying terminal 31 is further pressed in along the z-axis direction from the state shown in FIG. 8(b), the back surface of the terminal surface 41a of the voltage detecting terminal 41 comes into contact with the terminal surface 31a of the current applying terminal 31 (see FIG. 8(c)). As a result, the entire surface of the terminal surface 31a of the current applying terminal 31 is connected to the voltage detecting terminal 41. As a result, when adjusting the capacitance, the contact area between the terminals increases, the contact resistance decreases, and the amount of heat generated can be suppressed.

[0052] Another example of the structure of the current applying terminals 31, 32 and the voltage detecting terminals 41, 42 will be described with reference to Fig. 9. Fig. 9 is a side view of the connection portion between the terminals of the resistance measuring device 1 and the terminals of the secondary battery 5. Fig. 9(a) shows the non-contact state, Fig. 9(b) shows the state during internal resistance measurement, and Fig. 9(c) shows the state during charge capacity adjustment.

[0053] A resilient contact member 31b is fixed to the current application terminal 31. The resilient contact member 31b is a metal leaf spring that has an elastic force in a direction that contacts the bus bar 61 (the negative direction of the z-axis) and is electrically connected to the main body of the current application terminal 31. The resilient contact member 31b contacts the terminal surface 31a and moves along the terminal surface 31a. The tip portion of the resilient contact terminal 31 is bent so as to apply an elastic force in a direction that contacts the bus bar 61 (the negative direction of the z-axis). A portion of the terminal surface 31a of the current application terminal 31 is notched, and the bent portion of the resilient contact member 31b is shaped so that it fits into the notched portion when it elastically deforms. When not in contact, the resilient contact member 31b is not in contact with the first contact portion 61b of the bus bar 61, and the voltage detection terminal 41 is not in contact with the second contact portion 61c or the terminal surface 31a of the current application terminal 31.

[0054] When the current application terminal 31 and the voltage detection terminal 41 are pushed in along the z-axis direction from the state shown in FIG. 9(a) and approach the bus bar 61, the elastic contact member 31b elastically deforms and comes into contact with the first contact portion 61b, and the terminal surface 41a of the voltage detection terminal 41 comes into contact with the second contact portion 61c, as shown in FIG. 9(b). Meanwhile, the rear surface of the terminal surface 41a of the voltage detection terminal 41 and the terminal surface 31a of the current application terminal 31 are separated and do not come into contact. The measurement current applied to the secondary battery 5 from the current application terminal 31a flows from the elastic contact member 31b through the first contact portion 61b to the bus bar 61 (see arrow i in FIG. 9(b)). At this time, the measurement current does not flow through the second contact portion 61c. Therefore, the measurement current can be applied to the secondary battery 5 without electrically interfering with the voltage detection terminal 41.

[0055] When the current applying terminal 31 is further pressed in along the z-axis direction from the state shown in FIG. 9(b), the rear surface of the terminal surface 41a of the voltage detecting terminal 41 comes into contact with the elastic contact member 31b (see FIG. 9(c)). This connects the terminal surface 31a of the current applying terminal 31 with the voltage detecting terminal 41. This increases the contact area between the terminals during capacitance adjustment, reducing contact resistance and suppressing heat generation. Furthermore, in the state shown in FIG. 9(c), the bent portion of the elastic contact member 31b fits into the notch, preventing the elastic contact member 31b from interfering with the cover surrounding the terminal.

[0056] Another example of the structure of the current applying terminals 31, 32 and the voltage detecting terminals 41, 42 will be described with reference to Fig. 10. Fig. 10 is a side view of the connection portion between the terminals of the resistance measuring device 1 and the terminals of the secondary battery 5. Fig. 10(a) shows the non-contact state, Fig. 10(b) shows the state during internal resistance measurement, and Fig. 10(c) shows the state during charge capacity adjustment.

[0057] 10 differs in that the elastic contact member 31b uses a spring probe instead of a metal leaf spring. The elastic contact member 31b is provided in a cutout portion of the terminal surface 31 of the current applying terminal 31, and has elastic force in a direction that contacts the bus bar 61 (the negative direction of the z-axis). As shown in FIG. 10(a), when not in contact, the elastic contact member 31b is not in contact with the first contact portion 61b of the bus bar 61, and the voltage detection terminal 41 is not in contact with the second contact portion 61c and the terminal surface 31a of the current applying terminal 31.

[0058] 10(b), when measuring the internal resistance, the elastic contact member 31b elastically deforms and comes into contact with the first contact portion 61b, and the terminal surface 41a of the voltage detection terminal 41 comes into contact with the second contact portion 61c. Meanwhile, the back surface of the terminal surface 41a of the voltage detection terminal 41 and the terminal surface 31a of the current application terminal 31 are separated and do not come into contact. When adjusting the capacitance, the back surface of the terminal surface 41a of the voltage detection terminal 41 comes into contact with the elastic contact member 31b, as shown in FIG. 10(c).

[0059] In this way, when the above-described structure of the terminal portions of the current application terminals 31, 32 and the voltage detection terminals 41, 42 is used, the connection state of each of the current application terminals 31, 32 and the voltage detection terminals 41, 42 can be switched between disconnection, measurement, and capacity adjustment by the pressing force of the current application terminals 31, 32. Furthermore, the switching of the connection state can be achieved without using switches such as the switches 23a to 23d of the first embodiment. Note that the pressing force of the current application terminals 31, 32 can be automated by controlling its driving with an electromagnetic actuator, a servo motor, or the like.

[0060] As described above, in this embodiment, the current applying terminals 31, 32 have elastic contact members 31b that have elastic force in a direction that contacts the electrical lead-out members, which are the tab leads 51-53 or the bus bars 61, 63, and are pressed against the electrical lead-out members by the elastic force. This makes it possible to automate capacity adjustment and measurement when they must be performed in sequence, such as when diagnosing the deterioration of used batteries. Furthermore, the simple mechanical mechanism eliminates the need for relays, preventing interruptions to the inspection process due to relay failure, allowing for productivity to be maintained and maintenance labor to be reduced.

[0061] Although the embodiments of the present invention have been described above, these embodiments are described to facilitate understanding of the present invention and are not described to limit the present invention. Therefore, each element disclosed in the above embodiments is intended to include all design modifications and equivalents that fall within the technical scope of the present invention. [Explanation of symbols]

[0062] 1...Resistance measuring device 5…Secondary battery 6...Battery pack 10…Measuring instrument 31, 32...Current application terminal 31b...Elastic contact member 41, 42...Voltage detection terminals 51~53... Tabreed 61b...first contact part 61c...Second contact part 61~63...Busbar 70...Substrate

Claims

1. A resistance measurement device for a secondary battery, which is connected to a plate-shaped electrical lead-out member that is either a lead for extracting electricity from inside the battery or a bus bar connected to the lead, and measures the resistance of the secondary battery, a current application terminal connected to the secondary battery; a voltage detection terminal connected to the secondary battery; a measuring instrument that measures the resistance of the secondary battery based on the voltage output from the voltage detection terminal; the current applying terminal is in surface contact with the electrical lead-out member at a first contact portion on a main surface of the electrical lead-out member; the voltage detection terminal contacts the electrical lead-out member at a second contact portion on the electrical lead-out member; the first contact portion is located closer to the secondary battery than the second contact portion on an electrical conduction path from the second contact portion to the secondary battery; The resistance measuring device, wherein the first contact portion and the second contact portion are arranged separately on a main surface of the electrical lead-out member.

2. In the resistance measuring device according to claim 1, the current applying terminal has a terminal surface that comes into surface contact with the electrical lead-out member, the terminal surface is rectangular having short and long sides, the short side is a side along the direction of current flow through the conduction path, the long side is a side along a direction perpendicular to the current-carrying direction, A resistance measuring device in which the area of ​​the terminal surface is large enough to satisfy the current carrying capacity of the current flowing through the current applying terminal.

3. 3. The resistance measuring device according to claim 1, The resistance measuring device has a resistance measuring terminal including the current applying terminal and the voltage detecting terminal, which is electrically divided into two terminals for applying current and detecting voltage.

4. The resistance measuring device according to any one of claims 1 to 3, the current applying terminal has a terminal surface that comes into surface contact with the electrical lead-out member, A resistance measuring device in which the terminal surface has a longitudinal direction perpendicular to the conduction direction of the measurement current flowing through the conduction path.

5. 2. The resistance measuring device according to claim 1, the current applying terminal has a terminal surface that comes into surface contact with the electrical lead-out member, A resistance measuring device in which the length of the terminal surface in the longitudinal direction is longer than the length of the electrical lead-out member in the width direction.

6. The resistance measuring device according to any one of claims 1 to 5, the electrical lead-out member has a bent portion, The current application terminal is in contact with the bent portion.

7. The resistance measuring device according to any one of claims 1 to 6, a substrate; The current application terminal and the voltage detection terminal are mounted on the substrate.

8. A resistance measurement device for a secondary battery, which is connected to a plate-shaped electrical lead-out member that is either a lead for extracting electricity from inside the battery or a bus bar connected to the lead, and measures the resistance of the secondary battery, a current application terminal connected to the secondary battery; a voltage detection terminal connected to the secondary battery; a measuring instrument that measures the resistance of the secondary battery based on the voltage output from the voltage detection terminal; the current applying terminal is in surface contact with the electrical lead-out member at a first contact portion on a main surface of the electrical lead-out member; the voltage detection terminal contacts the electrical lead-out member at a second contact portion on the electrical lead-out member; the first contact portion is located closer to the secondary battery than the second contact portion on an electrical conduction path from the second contact portion to the secondary battery; The resistance measuring device includes wiring for electrically connecting the current applying terminal and the voltage detecting terminal, the voltage detection terminal is in surface contact with the electrical lead-out member; When adjusting the charge capacity of the secondary battery, the current application terminal and the voltage detection terminal are electrically connected via the wiring.

9. The resistance measuring device according to any one of claims 1 to 8, The current applying terminal has an elastic contact member that has an elastic force in a direction in which it contacts the electrical lead-out member, and is brought into pressure contact with the electrical lead-out member by the elastic force.

10. An inspection system including the resistance measuring device according to any one of claims 1 to 9. An inspection system including a rack that houses the secondary battery.

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