Voltage detection device for battery module

Abstract

In order to suppress disconnection of conducting wires (12), the present invention comprise a plurality of the conducting wires (12) each having one end connected to a to-be-detected part of a battery cell (21) and another end connected to an input unit of a controller (25), and an outer shell (11) covering the plurality of conducting wires, wherein: the outer shell has a repeating shape in which the cross-sectional shape perpendicular to an extension direction is constant and a plurality of iterative units are repeated, and one end of the outer shell is fixed to one pressurizing part (23a) and another end is directly or indirectly fixed to another pressurizing part (23b); and the respective one ends of the plurality of conducting wires are guided to the outside of the outer shell from iterative units, from among the plurality of iterative units, that are different from one another, and are connected to to-be-detected parts, from among the abovementioned to-be-detected parts, that are different from one another.

Description

Battery module voltage detection device

[0001] The present invention relates to a voltage detection device for a battery module.

[0002] A known wire harness with a simple configuration that allows easy adjustment of the length of an electric wire includes an electric wire having a bent portion that is bent in a stretchable manner, and the length between both ends of the electric wire can be adjusted by stretching the bent portion, and an exterior member having a resin tubular portion through which the electric wire is inserted and in which the bent portion is housed (Patent Document 1).

[0003] JP 2017-130999 A

[0004] However, if the above-mentioned conventional wire harness is used as a voltage detection conductor for a battery module, the battery cells expand and contract as the secondary battery is charged and discharged, and this expansion and contraction exerts a tensile force on the wire harness, which may cause it to break.

[0005] An object of the present invention is to provide a voltage detection device for a battery module that can prevent breakage of conductors.

[0006] The present invention solves the above problem by comprising a plurality of conductors, one end of which is connected to a detectable portion of a battery cell and the other end of which is connected to an input portion of a controller, and an outer shell covering the plurality of conductors, wherein the outer shell has a constant cross-sectional shape perpendicular to the extension direction and a repeating shape in which a plurality of repeating units are repeated, one end of which is fixed to one of the pressure applying portions and the other end of which is fixed directly or indirectly to the other pressure applying portion, and wherein each of the one ends of the plurality of conductors is led out of the outer shell from a mutually different repeating unit and connected to a mutually different detectable portion.

[0007] According to the present invention, breakage of the conductor wire can be suppressed.

[0008] 1 is a side view showing an embodiment of a battery module to which a voltage detection device according to the present invention is applied; FIG. 2 is a plan view of the battery module of FIG. 1; FIG. 3 is a cross-sectional view taken along line III-III of FIG. 2; FIG. 4 is a perspective view showing an outer shell of FIG. 1; FIG. 5 is a side view for explaining the operation of the voltage detection device of FIG. 1; FIG. 6 is a side view of a battery module showing another embodiment of a voltage detection device according to the present invention; FIG. 7 is a side view of a battery module showing yet another embodiment of a voltage detection device according to the present invention; FIG. 8 is a cross-sectional view taken along line VIII-VIII of FIG. 7; FIG. 9 is a side view of a battery module showing yet another embodiment of a voltage detection device according to the present invention; FIG. 10 is a front view of a battery module showing yet another embodiment of a voltage detection device according to the present invention; FIG. 11 is a side view of a battery module showing yet another embodiment of a voltage detection device according to the present invention;

[0009] Hereinafter, with reference to the drawings, an embodiment of the present invention will be described. Fig. 1 is a side view showing one embodiment of a battery module 2 to which a voltage detection device 1 according to the present invention is applied. Fig. 2 is a plan view of the battery module 2 of Fig. 1. Fig. 3 is a cross-sectional view taken along line III-III of Fig. 2. Fig. 4 is a perspective view showing the outer shell 11 of Fig. 1. Fig. 5 is a side view illustrating the operation of the voltage detection device 1. Fig. 6 is a side view of a battery module showing another embodiment of the voltage detection device 1 according to the present invention. In Figs. 1 to 12, XYZ indicate a three-dimensional space when the battery module 2 is mounted on a vehicle, the Z axis indicates the vertical direction of the vehicle, and the X and Y axes indicate the front-rear and left-right directions of the vehicle.

[0010] The battery module 2 of this embodiment includes a battery cell 21 having an output terminal 24, a stack 22 in which a plurality of battery cells 21 are stacked, a pressure mechanism (pressure units 23a, 23b) that presses the stack 22 in the stacking direction X of the battery cells 21, and a controller 25. In this embodiment, the battery module 2 is provided with a voltage detection device 1 that detects the voltage of the battery cell 21, and the detected voltage is read out by the controller 25.

[0011] The battery cells 21 included in the battery module 2 of this embodiment are not particularly limited as long as they are battery cells whose electrode thicknesses change during charging and discharging, and various types of battery cells can be used. Examples of such battery cells 21 include, but are not limited to, all-solid-state batteries and semi-solid-state batteries. An all-solid-state battery is a rechargeable secondary battery that uses a solid electrolyte as an electrolyte, and also includes a solid electrolyte containing a small amount of liquid material. A semi-solid-state battery is a rechargeable secondary battery that uses a gel electrolyte as an electrolyte. In this type of battery cell 21, the positive electrode layer and the negative electrode layer expand and contract during charging and discharging, with the expansion and contraction of the negative electrode layer being particularly significant compared to the positive electrode layer.

[0012] The battery cell 21 of this embodiment is not particularly limited, but may be, for example, a battery cell 21 containing metallic lithium or a metallic lithium alloy as the negative electrode active material. The battery cell 21 of this embodiment can be configured by housing a stack of a positive electrode layer, a negative electrode layer, an electrolyte layer, a positive electrode current collector, and a negative electrode current collector in an exterior member such as a laminate film, and by leading out a positive electrode terminal and a negative electrode terminal from the exterior member.

[0013] The battery module 2 of this embodiment is used by connecting a plurality of battery cells 21 (four in the example shown in FIG. 1 ) in series and / or parallel, and connecting another battery module or a load to the positive electrode terminal on one side of the connected battery cells and the negative electrode terminal on the other side.

[0014] Battery cells 21 used under pressure, such as all-solid-state or semi-solid-state batteries, require a pressure treatment to bond the interfaces between the solid or semi-solid electrolyte layer and the positive and negative electrode layers. Therefore, the pressure mechanism of this embodiment presses the stack 22 of the battery module 2 in the stacking direction X of the battery cells 21. As shown in FIGS. 1 and 2 , the pressure mechanism of this embodiment includes pressure members 23 a, 23 b formed of a pair of end plates and a pressure actuator (not shown). One or both of the pair of pressure members 23 a, 23 b are moved toward or away from each other by the pressure actuator, thereby applying or removing a desired surface pressure to the stack 22 located between the pair of pressure members 23 a, 23 b. Furthermore, when the battery cells 21 expand or contract during charging or discharging, one or both of the pair of pressure members 23 a, 23 b also move in the X-axis direction (shown).

[0015] The pressure actuator is composed of a fluid pressure cylinder, a pantograph jack, a feed screw mechanism, etc., and is driven by a control signal from the controller 25, thereby controlling the surface pressure applied to the main surfaces of the battery cells 21. The pressure mechanism shown in the figure is one example of a pressure mechanism included in the battery module 2 to which the voltage detection device 1 according to the present invention is applied, and is not intended to be limited to this type of pressure mechanism. Any pressure mechanism that can apply a predetermined range of surface pressure to the main surfaces of the battery cells 21 will do.

[0016] The voltage detection device 1 of this embodiment is a device that detects the voltage between the positive and negative terminals of each battery cell 21 and outputs the voltage to the controller 25. Hereinafter, the positive and negative terminals of the battery cells 21 are also simply referred to as output terminals 24. The voltage detection device 1 of this embodiment has a plurality of conductors 12, one end of which is connected to the output terminal 24 of the battery cell 21 (corresponding to the detected portion according to the present invention) and the other end of which is connected to the input portion of the controller 25, and an outer shell 11 that covers the plurality of conductors 12.

[0017] The outer shell 11 of this embodiment is formed from an electrically insulating material, such as a synthetic resin, that is flexible and expandable at least in the extension direction (which is also the axial direction of the outer shell 11). The outer shell 11 of this embodiment is preferably coated with a coating film having an emissivity of 0.9 or higher. Furthermore, the outer shell 11 of this embodiment has a uniform cross-sectional shape perpendicular to the extension direction, and has a repeating shape in which a plurality of repeat units are repeated. As shown in FIGS. 1 and 2 , one end of the outer shell 11 of this embodiment is fixed to one of the pressure members 23 a, 23 b, and the other end is directly or indirectly fixed to the other of the pressure members 23 a, 23 b.

[0018] When both of the pair of pressure members 23a, 23b are movable end plates, the outer shell 11 of this embodiment has one end directly fixed to one of the pressure members 23a and the other end directly fixed to the other pressure member 23b, as shown in Figures 1 and 2. The outer shell 11 expands and contracts as both pressure members 23a, 23b move toward and away from each other. In contrast, when only one of the pair of pressure members 23a, 23b (e.g., 23b) is movable and the other pressure member (e.g., 23a) is a stationary end plate, the outer shell 11 of this embodiment has one end directly fixed to the movable pressure member 23b, but the other end may be directly fixed to the stationary pressure member 23a or may be fixed to a stationary member other than the stationary pressure member 23a. The outer shell 11 expands and contracts as the movable pressure member 23b moves toward and away from the stationary pressure member 23a.

[0019] The outer shell 11 of the embodiment shown in Figures 1 and 2 has a repeating shape in which a plurality of wave-shaped repeat units are repeated, as shown in the side view of Figure 1 and the perspective view of Figure 4. The cross-sectional shape of the outer shell 11 perpendicular to the direction of extension from one end to the other end has a flat, uniform shape, as shown in Figure 3, and four conducting wires 12 are inserted inside.

[0020] Although not particularly limited, the outer shell 11 of this embodiment preferably has a repeating shape in which a repeat unit including a curved portion is repeated multiple times, like the apex of a corrugated shape. Furthermore, the outer shell 11 of this embodiment more preferably has a repeating shape in which a pair of semicircular repeat units is repeated multiple times, as shown in Fig. 6 . However, the outer shell 11 of this embodiment may have a corrugated shape in which the apex of the corrugated shape is sharply folded, as long as the length of expansion and contraction in the extension direction is uniform.

[0021] In this embodiment, the conductors 12 are made of a metal material with high electrical conductivity, such as copper or a copper alloy, and the number of conductors 12 is the same as the number of battery cells 21, i.e., four conductors for four battery cells 21. As described above, one end of the conductors 12 is connected to the input unit of the controller 25 as shown in FIG. 2 , and the other end is connected to each of the output terminals 24 of the four battery cells 21. Then, each of one ends of the multiple conductors 12 is led out of the outer shell 11 from a different repeat unit and connected to the output terminal 24 of a different battery cell 21.

[0022] That is, in the case of the four conductors 12 shown in the plan view of Figure 2, each having one end connected to the controller 25, for example, the top conductor 12 is connected to the output terminal 24 of the leftmost battery cell 21, the second conductor 12 from the top is connected to the output terminal 24 of the second battery cell 21 from the left, the third conductor 12 from the top is connected to the output terminal 24 of the third battery cell 21 from the left, and the bottom conductor 12 is connected to the output terminal 24 of the rightmost battery cell 21. 1, the topmost conductor 12 in FIG. 2 is led out from the top of the leftmost waveform in FIG. 1 and connected to the output terminal 24 of the leftmost battery cell 21, the second conductor 12 from the top in FIG. 2 is led out from the top of the second leftmost waveform in FIG. 1 and connected to the output terminal 24 of the second leftmost battery cell 21, the third conductor 12 from the top in FIG. 2 is led out from the top of the third leftmost waveform in FIG. 1 and connected to the output terminal 24 of the third leftmost battery cell 21, and the bottommost conductor 12 in FIG. 2 is led out from the top of the rightmost waveform in FIG. 1 and connected to the output terminal 24 of the rightmost battery cell 21.

[0023] As shown in FIG. 1 , the other ends of the multiple conductors 12 are led out of the outer shell 11 from the symmetrical portion of the repeating unit that is closest to the output terminal 24. In other words, in the side view shown in FIG. 1 , the repeating shape of the waveform repeating unit is a vertically symmetrical shape with a phase in the X-axis direction, as indicated by the dashed-dotted line L, and of the upper and lower halves of the dashed-dotted line L, the lower half is closer to the output terminal 24. Therefore, each of the four conductors 12 is led out of the outer shell 11 from the symmetrical portion of the lower half of the repeating shape and connected to the output terminal 24. In particular, each of the four conductors 12 in the embodiment shown in FIG. 1 extends vertically from the apex of the waveform in the symmetrical portion of the lower half and is connected to the output terminal 24. It is preferable that the conductors 12 in this embodiment be coated with a coating having an emissivity of 0.9 or higher.

[0024] Next, the operation will be described. FIG. 5 is a side view showing a state in which the length in the X-axis direction of the stack 22 increases from X1 to X2 (X2 > X1) by charging the four battery cells 21 shown in FIG. 1 . As described above, in the battery cells 21 containing metallic lithium or a metallic lithium alloy as the negative electrode active material, the thickness of the electrode layer (particularly the negative electrode layer) increases when charged, and decreases when discharged. As a result, the battery cells 21 expand in the X-axis direction when charged and contract in the X-axis direction when discharged. Then, as shown in FIG. 5 , when the four battery cells 21 are charged, each battery cell 21 expands in the X-axis direction, and the length in the X-axis direction of the stack 22 increases from X1 to X2.

[0025] At this time, the spacing between the pair of pressure members 23a, 23b increases in response to the expansion of the laminate 22 in the X-axis direction, causing the outer shell 11 of the voltage detection device 1 to also expand in the X-axis direction. Because the outer shell 11 has a repeating shape in which repeating units are repeated, the peaks of the waveform shape from which the four conductors 12 are derived also expand at equal intervals. Therefore, as shown in FIG. 5 , even if each of the four battery cells 21 expands in the X-axis direction and the position of the output terminal 24 moves, the distance between each of the peaks of the waveform shape from which the four conductors 12 are derived does not change. This suppresses the generation of tensile stress acting on the conductors 12, particularly tensile stress acting on the connection (e.g., weld) between the conductors 12 and the output terminal 24, thereby preventing disconnection.

[0026] When discharging begins from the charged state shown in FIG. 5 , the length of the laminate 22 in the X-axis direction decreases from X2 to X1 as shown in FIG. 1 . At this time, the spacing between the pair of pressure members 23 a, 23 b also decreases in response to the shrinkage of the laminate 22 in the X-axis direction, causing the outer shell 11 of the voltage detection device 1 to also shorten in the X-axis direction. Because the outer shell 11 has a repeating shape in which repeating units are repeated, the peaks of the waveform shape from which the four conductors 12 lead also shorten at equal intervals. Therefore, even if each of the four battery cells 21 shrinks in the X-axis direction and the position of the output terminal 24 moves, as shown in FIG. 1 , the distance between each of the peaks of the waveform shape from which the four conductors 12 lead does not change. This suppresses tensile stress acting on the connection (e.g., weld) between the conductors 12 and the output terminal 24, preventing disconnection.

[0027] The outer shell 11 of the present invention is not limited to the repeating shape of the repeating unit having a wave shape as shown in Figures 1 to 6, but may have any shape as long as the cross-sectional shape perpendicular to the extension direction is constant and the repeating unit is repeated multiple times. Figure 7 is a side view of a battery module 2 showing yet another embodiment of the voltage detection device 1 of the present invention, and Figure 8 is a cross-sectional view taken along line VIII-VIII in Figure 7. Since the battery module 2 of this embodiment has the same configuration as the battery module 2 shown in Figure 1, the same reference numerals are used in Figure 7, and the description of Figure 1 is incorporated herein by reference.

[0028] The voltage detection device 1 of this embodiment is also a device that detects the voltage between the positive and negative terminals of each battery cell 21 and outputs the voltage to the controller 25, and has a plurality of conductors 12, one end of which is connected to the output terminal 24 of the battery cell 21 (corresponding to the detected part in the present invention) and the other end of which is connected to the input part of the controller 25, and an outer shell 11 that covers these plurality of conductors 12.

[0029] The outer shell 11 of this embodiment is formed from a flexible, electrically insulating material, such as a synthetic resin, that is expandable and contractible at least in the extension direction (which is also the axial direction of the outer shell 11). The outer shell 11 of this embodiment has a constant diameter in the extension direction and a repeating shape in which a plurality of spiral repeat units are repeated. As shown in FIG. 7 , one end of the outer shell 11 of this embodiment is fixed to one of the pressure members 23 a, 23 b, and the other end is directly or indirectly fixed to the other of the pressure members 23 a, 23 b. For example, if both of the pair of pressure members 23 a, 23 b are movable end plates, the outer shell 11 of this embodiment has one end directly fixed to one of the pressure members 23 a, and the other end directly fixed to the other pressure member 23 b, as shown in FIG. 7 . The outer shell 11 expands and contracts as the pressure members 23 a, 23 b move toward and away from each other. In contrast, when only one of the pair of pressure members 23a, 23b (for example, 23b) is movable and the other pressure member (for example, 23a) is a stationary end plate, outer shell 11 of this embodiment has one end directly fixed to movable pressure member 23b, but the other end directly fixed to stationary pressure member 23a, or may be fixed to a stationary member other than stationary pressure member 23a. As movable pressure member 23b moves toward and away from stationary pressure member 23a, outer shell 11 expands and contracts.

[0030] The outer shell 11 of this embodiment shown in Fig. 7 has a repeating shape in which a plurality of spiral repeat units are repeated. The cross section of the outer shell 11 perpendicular to the direction of extension from one end to the other end has a uniform circular shape as shown in Fig. 8, and four conducting wires 12 are inserted inside.

[0031] In this embodiment, the conductors 12 are made of a metal material with high electrical conductivity, such as copper or a copper alloy, and the number of conductors 12 is the same as the number of battery cells 21, i.e., four conductors for four battery cells 21. As described above, one end of the conductors 12 is connected to the input unit of the controller 25 as shown in FIG. 7 , and the other end is connected to each of the output terminals 24 of the four battery cells 21. Then, each of one ends of the multiple conductors 12 is led out of the outer shell 11 from a different repeat unit and connected to the output terminals 24 of a different battery cell 21.

[0032] The other ends of the multiple conducting wires 12 are each led out of the outer shell 11 from a symmetrical portion of the spiral repeat unit that is closer to the output terminal 24. In other words, in the side view shown in Figure 7, the repeating shape of the spiral repeat unit is a vertically symmetrical shape with a phase in the X-axis direction, as shown by the dashed-dotted line L in the figure, and of the upper and lower halves of the dashed-dotted line L, the lower half is closer to the output terminal 24. Therefore, each of the four conducting wires 12 is led out of the outer shell 11 from a symmetrical portion of the lower half of the repeating shape and connected to the output terminal 24. In particular, each of the four conducting wires 12 in the embodiment shown in Figure 7 extends vertically from the lower end of the spiral shape in the symmetrical portion of the lower half and is connected to the output terminal 24.

[0033] Next, the operation will be explained. As described above, in a battery cell 21 containing metallic lithium or a metallic lithium alloy as the negative electrode active material, the thickness of the electrode layer (particularly the negative electrode layer) increases when the battery cell 21 is charged, and decreases when the battery cell 21 is discharged. As a result, the battery cell 21 expands in the X-axis direction when the battery cell 21 is charged, and contracts in the X-axis direction when the battery cell 21 is discharged. When the four battery cells 21 shown in FIG. 7 are charged, each battery cell 21 expands in the X-axis direction, and the length of the stack 22 in the X-axis direction increases.

[0034] At this time, the spacing between the pair of pressure members 23a, 23b increases in response to the expansion of the laminate 22 in the X-axis direction, causing the outer shell 11 of the voltage detection device 1 to also expand in the X-axis direction. Because the outer shell 11 has a repeating shape in which repeat units are repeated, the bottom ends of the spiral shapes from which the four conductors 12 are derived also expand at equal intervals. Therefore, as shown in FIG. 7 , even if each of the four battery cells 21 expands in the X-axis direction and the position of the output terminal 24 moves, the distance between each of the four battery cells 21 and the bottom ends of the spiral shapes from which the four conductors 12 are derived does not change. This suppresses the generation of tensile stress acting on the connection (e.g., weld) between the conductors 12 and the output terminal 24, preventing disconnection.

[0035] Furthermore, when discharging begins from a charged state, the length of the laminate 22 in the X-axis direction decreases. At this time, the spacing between the pair of pressure members 23 a, 23 b also decreases in response to the shrinkage of the laminate 22 in the X-axis direction, causing the outer shell 11 of the voltage detection device 1 to shorten in the X-axis direction. Because the outer shell 11 has a repeating shape in which repeating units are repeated, the bottom ends of the spiral shapes from which the four conductors 12 lead out also shorten at equal intervals. Therefore, even if each of the four battery cells 21 shrinks in the X-axis direction and the position of the output terminal 24 moves, the distance between each of the four battery cells 21 and the bottom ends of the spiral shapes from which the four conductors 12 lead out remains unchanged. This suppresses tensile stress acting on the connection (e.g., weld) between the conductors 12 and the output terminal 24, preventing disconnection.

[0036] If the outer shell 11 according to the present invention is formed as a spiral repeating unit extending horizontally, there is a risk of vertical vibration. Therefore, the shaft member 13 may be inserted through the center of the extension direction of the outer shell 11. FIG. 9 is a side view of a battery module 2 illustrating yet another embodiment of the voltage detection device 1 according to the present invention. In this embodiment, the pair of pressure members 23a, 23b are provided with the shaft member 13, and the outer shell 11 is wrapped around the outer periphery of the shaft member 13. The shaft member 13 is slidable relative to the pressure members 23a, 23b so as not to hinder the approaching and separating movement of the pair of pressure members 23a, 23b. Furthermore, although the shaft member 13 is inserted through the center of the spiral-shaped outer shell 11, it is sufficient that the insertion state is such that vibration of the outer shell 11 is suppressed without hindering the expansion and contraction of the outer shell 11.

[0037] Furthermore, when the spiral-shaped outer shell 11 is formed as shown in FIG. 7 , the spiral shape when viewed from the axial direction of the spiral shape (X-axis direction) may be a perfect circle or an ellipse. FIGS. 10A and 10B are front views (viewed along the X-axis arrow) of a battery module 2 illustrating yet another embodiment of a voltage detection device 1 according to the present invention. In FIG. 10A , the outer shell 11 is shown as viewed in the axial direction of the outer shell 11, i.e., a front view along the X-axis direction. The spiral-shaped outer shell 11 shown in FIG. 10A is an example in which the major axis of the ellipse is arranged horizontally and the minor axis of the ellipse is arranged vertically. In contrast, the spiral-shaped outer shell 11 shown in FIG. 10B is an example in which the major axis of the ellipse is arranged vertically and the minor axis of the ellipse is arranged horizontally.

[0038] When the outer shell 11 is arranged as shown in Fig. 10A, the vertical length Z1 of the battery module 2 can be set relatively shorter (Z1 < Z2) than when the outer shell 11 is arranged as shown in Fig. 10B. Conversely, when the outer shell 11 is arranged as shown in Fig. 10B, the Y-axis length Y2 of the battery module 2 can be set relatively shorter (Y2 < Y1) than when the outer shell 11 is arranged as shown in Fig. 10A. In this way, the degree of design freedom can be increased depending on the shape of the space in which the battery module 2 is arranged.

[0039] 11 and 12 are side views of a battery module 2 illustrating yet another embodiment of the voltage detection device 1 according to the present invention. When four battery cells 21 shown in FIG. 11 are charged, each of the four battery cells 21 expands in the X-axis direction. The battery cell 21 located farthest from the pressure applying portion 23a on the controller 25 has a movement error equal to not only its own expansion length error but also the sum of the expansion length errors of the other three battery cells 21. Therefore, the battery cell 21 located farthest from the pressure applying portion 23a on the controller 25 must have a longer extension length of its conductor 12 to take these errors into account. Therefore, in the embodiment shown in FIG. 11 , the length of each of the multiple conductors 12 from the position where one end of each conductor 12 is led out of the outer shell 11 to the output terminal 24 is set longer for the conductor 12 connected to the battery cell 21 that has moved the greatest distance from one pressure applying portion 23a.

[0040] Furthermore, if the length of the conductors 12 is set in this way taking into account the length of expansion during expansion, the conductors 12 will slacken as the battery cells 21 are located farthest from the pressure application portion 23a, as shown in Fig. 11. Therefore, as shown in Fig. 12, the longer the length of each of the conductors 12 from the position where one end of each conductor 12 is led out of the outer shell 11 to the output terminal 24, the farther the position where it is led out of the outer shell 11 will be from the output terminal 24. This makes it possible to prevent slack in the conductors 12 that would occur if the battery cells 21 were not expanded.

[0041] As described above, the voltage detection device 1 of this embodiment is a voltage detection device 1 for detecting the voltage of a battery cell 21 in a stack 22 in which a plurality of battery cells 21 are stacked, and in which pressure sections 23 a, 23 b are arranged at both ends of the stack 22 in the stacking direction X, and at least one of the pressure sections 23 a, 23 b moves in accordance with the expansion or contraction of the stack 22. In the voltage detection device 1, one end is connected to the output terminal 24, which is the detected part of the battery cell 21, and the other end is connected to the controller 25. and an outer shell 11 covering the plurality of conductors 12, wherein the outer shell 11 has a repeating shape in which a cross-sectional shape perpendicular to the extension direction is constant and a plurality of repeating units are repeated, one end of which is fixed to one of the pressure applying portions 23 a and the other end of which is fixed directly or indirectly to the other pressure applying portion 23 b, and each of the one ends of the plurality of conductors 12 is led out of the outer shell 11 from a different repeating unit and connected to an output terminal 24 which is a different detected portion.

[0042] Because the shell 11 of this embodiment has a repeating shape in which the repeating unit is repeated, the repeating shape from which the four conductors 12 lead out also expands or contracts at equal intervals as the laminate 22 expands or contracts. Therefore, even if each of the four battery cells 21 expands or contracts in the X-axis direction and the position of the output terminal 24 moves, the distance from each of the repeating shapes from which the four conductors 12 lead out does not change. This makes it possible to suppress the generation of tensile stress acting on the conductors 12, particularly tensile stress acting on the connection (e.g., weld) between the conductors 12 and the output terminal 24, and to prevent breakage.

[0043] In addition, in the voltage detection device 1 of this embodiment, the outer shell 11 has a repeating shape in which repeating units including curved portions are repeated multiple times, so that the repeating shape from which the four conductors 12 are derived also smoothly extends or shortens at equal intervals as the laminate 22 expands or contracts.

[0044] Furthermore, in the voltage detection device 1 of this embodiment, the outer shell 11 has a constant width in the extension direction and a repeating shape in which the waveform repeat unit is repeated multiple times, so that the generation of tensile stress acting on the conductor 12, particularly tensile stress acting on the connection portion (such as welding) between the conductor 12 and the output terminal 24, can be suppressed, and breakage can be prevented.

[0045] Furthermore, in the voltage detection device 1 of this embodiment, the outer shell 11 has a repeating shape in which semicircular repeating units are repeated multiple times, so that the stress acting on the outer shell when the outer shell 11 itself is deformed by extension and contraction is uniform, and stress concentration on the outer shell 11 can be suppressed.

[0046] Furthermore, in the voltage detection device 1 of this embodiment, the outer shell 11 has a constant diameter in the extension direction and a repeating shape in which multiple spiral repeating units are repeated, so that the generation of tensile stress acting on the conductor 12, particularly tensile stress acting on the connection portion (such as welding) between the conductor 12 and the output terminal 24, can be suppressed, and breakage can be prevented.

[0047] In addition, in the voltage detection device 1 of this embodiment, an axial member 13 is inserted at the center of the extension direction of the outer shell in which the spiral repeating unit is repeated multiple times, so that vibration of the outer shell 11 and the conductor 12 can be suppressed and the stress acting on the outer shell 11 and the conductor 12 due to vibration can be reduced.

[0048] Furthermore, in the voltage detection device 1 of this embodiment, the repeating unit of the spiral shape of the outer shell 11 is elliptical, which increases the degree of freedom in design according to the shape of the space in which the battery module 2 is arranged.

[0049] In addition, in the voltage detection device 1 of this embodiment, each of the ends of the multiple conductors 12 is led out to the outside of the outer shell 11 from the symmetrical part of the multiple repeated units that is closer to the output terminal 24, which is the part to be detected, so that the conductors 12 led out from the outer shell 11 can be prevented from interfering with the expansion and contraction movement of the outer shell 11.

[0050] Furthermore, in the voltage detection device 1 of this embodiment, the length of each of the ends of the plurality of conductors 12 from the position where it is led outside the outer shell 11 to the output terminal 24, which is the detected part, is set to be longer for conductors 12 connected to battery cells 21 that have a greater amount of movement from the pressure sections 23 a, 23 b. This makes it possible to absorb errors in the thickness of the battery cells 21 and errors in the amount of expansion and contraction, and to suppress the generation of tensile stress acting on the conductors 12 due to these errors.

[0051] Furthermore, in the voltage detection device 1 of this embodiment, the longer the length of each of the ends of the multiple conductors 12 from the position where it is led out outside the outer shell 11 to the output terminal 24, which is the detected part, the farther the position where it is led out outside the outer shell 11 is set from the output terminal 24, which is the detected part, so that loosening of the conductors 12 that occurs when the battery cell 21 does not expand can be prevented.

[0052] Furthermore, in the voltage detection device 1 of this embodiment, the conductor 12 from the position where the outer shell 11 and the conductor 12 are led out of the outer shell 11 to the output terminal 24, which is the detected part, is positioned vertically above the output terminal 24, which is the detected part, as shown in Figures 1 and 7, so that it is possible to suppress the occurrence of tensile stress due to gravity of the conductor 12 at the connection part (welding, etc.) between the conductor 12 and the output terminal 24.

[0053] Furthermore, in the voltage detection device 1 of this embodiment, the outer shell 11 and the conductors 12 are coated with a coating having an emissivity of 0.9 or more, so that the radiant heat from the output terminals 24, which are non-detection parts, can be absorbed and this heat can be radiated to the housing of the battery module 2, etc. This allows the output terminals 24 to be cooled.

[0054] Furthermore, in the voltage detection device 1 of this embodiment, lithium metal or lithium metal alloy is precipitated on the negative electrode of the battery cell 21 during charging, so the effect of the outer shell 11 on the expansion and contraction of the battery cell 21 is further enhanced.

[0055] DESCRIPTION OF SYMBOLS 1... Voltage detection device 11... Outer shell 12... Conductive wire 13... Shaft member 2... Battery module 21... Battery cell 22... Laminated body 23a, 23b... Pressurizing section (pressurizing mechanism) 24... Output terminal 25... Controller

Claims

1. A voltage detection device for detecting the voltage of a battery cell in a stack of multiple stacked battery cells, wherein a pressure member is disposed at each end of the stack in the stacking direction, and at least one of the pressure members moves in accordance with the expansion or contraction of the stack; the voltage detection device comprises: a plurality of conductors, one end of which is connected to the portion to be detected of the battery cell, and the other end of which is connected to the input portion of a controller; and an outer shell covering the plurality of conductors, wherein the outer shell has a constant cross-sectional shape perpendicular to the extension direction and a repeating shape in which multiple repeat units are repeated, one end of which is fixed to one of the pressure members and the other end of which is fixed directly or indirectly to the other pressure member; and wherein each of the one ends of the plurality of conductors is led out of the outer shell from a mutually different repeat unit and connected to a mutually different portion to be detected.

2. The voltage detection device according to claim 1, wherein the outer shell has a repeating shape in which a repeating unit including a curved portion is repeated a plurality of times.

3. A voltage detection device according to claim 1 or 2, wherein the outer shell has a constant width in the extension direction and a repeating shape in which a waveform repeat unit is repeated multiple times.

4. The voltage detection device according to claim 3, wherein the outer shell has a repeating shape in which a plurality of semicircular repeating units are repeated.

5. A voltage detection device according to claim 1 or 2, wherein the outer shell has a constant diameter in the extension direction and a repeating shape in which a spiral repeat unit is repeated a plurality of times.

6. A voltage detection device according to claim 5, wherein a shaft member is inserted through the center of the outer shell in the extending direction, where the spiral repeating unit is repeated a plurality of times.

7. A voltage detection device according to claim 5 or 6, wherein the spiral repeating unit of the outer shell is elliptical in shape.

8. A voltage detection device as claimed in any one of claims 1 to 7, wherein each of the one ends of the plurality of conductors is led out of the outer shell from a symmetrical portion of the plurality of repeating units that is closer to the detection portion.

9. A voltage detection device as claimed in any one of claims 1 to 8, wherein the length of each of the ends of the plurality of conductors from the position where it is led outside the outer shell to the detection part is set to be longer for conductors connected to battery cells that have a greater amount of movement from the pressure part.

10. A voltage detection device as described in claim 9, wherein the longer the length of each of the ends of the plurality of conductors from the position where it is led out outside the outer shell to the detected portion, the farther the position where it is led out outside the outer shell is set from the detected portion.

11. A voltage detection device as claimed in any one of claims 1 to 10, wherein the outer shell and the conductor from the position where they are led out of the outer shell to the detected part are positioned vertically above the detected part.

12. A voltage detection device according to any one of claims 1 to 11, wherein the outer shell and the conductors are coated with a coating having an emissivity of 0.9 or more.

13. A voltage detection device according to any one of claims 1 to 12, wherein lithium metal or a lithium metal alloy is deposited on the negative electrode of the battery cell during charging.

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