Battery module and battery pack containing the battery module

Abstract

To provide a battery module capable of accurately measuring the state of cells from outside and a battery pack that accommodates the same.SOLUTION: The battery module accommodates a plurality of laminated cells in a case. Since the case has at least one through window and a tab of each of the plurality of cells is provided at a position visible from the through hole, the state of the cells can be measured by pressing a contact point of a probe against the tab closest to an electrode. Thereby, the state of cells can be accurately estimated.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a battery module, and more particularly to a battery module that enables the deterioration state of cells inside the battery module to be measured from outside the battery module, and a battery pack that houses the battery module. [Background technology]

[0002] The drive battery packs used in electric vehicles and other vehicles are equipped with multiple battery modules, each of which has multiple cells connected in series to increase output voltage. For safety reasons, the battery module must cover the cells with a case as much as possible.

[0003] On the other hand, in order to maintain good battery characteristics of the cells, it is necessary to measure the current value, cell voltage, cell temperature, etc. of each cell inside the battery module from outside the battery module and estimate the state of each cell.

[0004] Patent Document 1 discloses that a part of the tab is bent to form a bent portion that extends toward the case, and a device for detecting the state of the cell is connected to this bent portion to estimate the state of the cell. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-249290 Summary of the Invention [Problem to be solved by the invention]

[0006] Electrochemical impedance spectroscopy (EIS) is known as a method for measuring the state of a cell.

[0007] This EIS method deals with the heterogeneous charge transfer phenomenon at the interface between the electrode and solution inside the cell. A minute amplitude, variable frequency AC potential is applied to the working electrode, and the state of the cell can be estimated from a Nyquist plot, which plots the real and imaginary components of the measured impedance response with frequency as a parameter.

[0008] However, if measurements are taken at a location away from the electrodes inside the cell, such as via a bus bar connected to the tab, the Nyquist plot will be distorted due to the influence of the bus bar resistance and electromagnetic noise generated by the bus bar, making it impossible to accurately estimate the state of the cell.

[0009] The present invention has been made in consideration of the problems associated with the prior art, and its purpose is to provide a battery module that can accurately measure the state of a cell, and a battery pack that houses the battery module. [Means for solving the problem]

[0010] As a result of extensive research into achieving the above object, the present inventors discovered that the above object can be achieved by providing a through-window in the case of a battery module and enabling EIS measurement on the tab closest to the electrode inside the cell, and thus completed the present invention.

[0011] That is, the battery module of the present invention houses a plurality of stacked cells in a case. The case has at least one through window, The above multiple cells The tab is flat, the through window is provided on a surface of the tab opposite to the main surface, Each of the tabs of the plurality of cells is provided at a position visible through the through window in the stacking direction of the cells. The tabs of the plurality of cells are each provided at a position visible from the through-hole.

[0012] The battery pack of the present invention is characterized in that it houses a plurality of the battery modules and has the through window on a surface facing an adjacent battery module. [Effects of the Invention]

[0013] According to the present invention, the case of the battery module has a through window, and each of the tabs of the multiple cells in the case is located in a position that is visible from the through hole, so that it is possible to provide a battery module that can accurately estimate the state of the cells, and a battery pack that houses the battery module. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is an exploded perspective view showing an example of a battery module of the present invention. FIG. [Figure 2] FIG. 10 is an exploded perspective view showing an example of a battery module in which tabs are arranged in a staggered manner. [Figure 3] FIG. 3 is a cross-sectional view of the battery module shown in FIG. 2 taken along a plane passing through the through window, showing an example of a state in which the probe and the tab of the EIS measurement unit are in contact with each other. [Figure 4] 10 is an exploded perspective view showing an example of a battery module in which tabs having through holes with gradually decreasing sizes are arranged side by side; FIG. [Figure 5] 10 is a perspective view showing an example of a probe that abuts against a tab having a through hole with a gradually decreasing size formed therein; FIG. [Figure 6] FIG. 5 is a cross-sectional view of the battery module shown in FIG. 4 taken along a plane passing through the through-window and the tab through-hole of the cell, showing an example of a state in which the probe and the tab of the EIS measurement unit are in contact with each other. [Figure 7] FIG. 10 is an exploded perspective view showing a state in which a probe equipped with a spring receives a reaction force from a spacer and abuts against a tab. [Figure 8] FIG. 10 is a schematic diagram showing an example of the arrangement of a battery module in which a through window is provided at a position where a probe cannot be inserted without removing the battery module from the battery pack. DETAILED DESCRIPTION OF THE INVENTION

[0015] <Battery module> The battery module of the present invention will now be described in detail. As shown in FIG. 1, the battery module accommodates a plurality of stacked cells in a case, and is provided with at least one through window.

[0016] The cell is a rectangular cell with tabs protruding from the side, and contains storage elements such as electrodes and electrolytes (not shown), with the tabs directly connected to the electrodes. Although FIG. 1 shows a case where both the positive electrode tab and the negative electrode tab are on only one side of the cell, they may be on both sides of the cell.

[0017] The tabs of each of the cells are positioned so that at least a portion of them is visible through the through-window, and the state of each cell can be measured by inserting a probe of the EIS unit through the through-window and pressing the contact point of the probe against the visible position of each tab.

[0018] Therefore, the state of the cell can be measured by pressing the contact point of the probe against the tab that is directly connected to the cell electrode and closest to the electrode, making it possible to accurately estimate the state of the cell.

[0019] In other words, compared to measuring the cell state by pressing the probe contacts against a point away from the electrode, such as when measuring via a bus bar, there is less error in the measurement value due to voltage drops caused by the resistance of the components between the electrode and the contacts, and electromagnetic noise and Joule heat generated in the components between them.

[0020] The tabs are insulated except for the area where the EIS unit probe contacts are pressed against them, preventing short circuits between tabs and incorrect probe connection and resulting short circuits.

[0021] It is preferable that the tab has a flat plate shape, and the through window is provided at a position facing a main surface of the flat plate-shaped tab.

[0022] If there is a through window located opposite the main surface of the flat tab, the probe can be inserted toward the main surface of the flat tab, thereby increasing the area against which the probe contacts can be pressed and stabilizing the contact state between the probe contacts and the tab, thereby improving measurement accuracy.

[0023] Furthermore, when the main surface of the tab is perpendicular to the stacking direction of the cells, the distance from the through window to the tab differs for each cell. Therefore, even when multiple probes are inserted to measure the state of multiple cells simultaneously, the cell to be measured can be identified by the insertion depth of the probe, and it is possible to prevent the inserted probe from coming into contact with multiple tabs and causing a short circuit.

[0024] In addition, if the tabs are flat, processing of the tabs and assembly of the cells are easy, and the structure of the battery module is simplified, making it possible to suppress increases in costs.

[0025] The through window may be provided on the surface of the case facing the main surface of the flat tab at a position where the tab can be seen from the stacking direction of the cells, i.e., directly above the tab, or at a position shifted from directly above the tab so that the tab can be seen from an oblique angle, as long as it is provided on the surface of the case facing the main surface of the flat tab. However, it is preferable that the through window is provided directly above the tab.

[0026] When a through window is provided directly above the tab, the probe can be pressed from a direction perpendicular to the main surface of the tab, which stabilizes the contact state between the probe contact point and the tab and minimizes the distance from the through window to the tab, improving measurement workability.

[0027] Furthermore, when the distance from the through window to the tab is shortened, the area of ​​the closed circuit formed by the path of the current flowing through the probe is reduced, thereby suppressing the induced electromotive force generated by the magnetic flux passing through the closed circuit, thereby improving measurement accuracy.

[0028] When a through window is provided directly above the tab, the following method can be used to arrange the tabs of all the cells in a position where at least a part of the tab is visible from the through window.

[0029] For example, the tabs of each cell can be arranged so that they are offset from one another in a direction perpendicular to the cell stacking direction, as shown in Figure 2. By arranging the tabs in this way, a probe can be inserted through the through-hole in the case and, by shifting the probe in a direction perpendicular to the cell stacking direction, the probe can be pressed against all the tabs of the cells, from the upper cell to the lower cell, in order.

[0030] Alternatively, for example, as shown in Figure 4, multiple tabs with through holes are arranged side by side so that the through holes overlap in the stacking direction of the cells, and the size of the lower through hole is made smaller than the upper through hole. By arranging the tabs in this way, a probe can be pressed against the lower tab through the through hole provided in the upper tab.

[0031] The battery module of the present invention can be equipped with an EIS measurement unit in the through-hole of the case. By providing probes that align with the arrangement of the tabs, it is possible to simultaneously measure the state of each cell.

[0032] Specifically, when the tabs are arranged as shown in Figure 2, multiple probes of different lengths can be provided to the EIS measurement unit as shown in Figure 3. These probes can be arranged in a line with the tabs offset, forming independent circuits. This makes it possible to press the probes against all the tabs simultaneously and measure the state of each cell.

[0033] Therefore, the impedance of each stacked cell can be measured simultaneously, and the status of all cells in the battery module can be monitored, improving safety.

[0034] When tabs with through holes that become smaller in size in stages are arranged as shown in Figure 4, the probe is shaped so that its cross section has a stepped shape, as shown in Figure 5, and the contact points with the tabs are formed on the surfaces of each step in a direction perpendicular to the longitudinal direction of the probe. The height of each step is then adjusted to match the spacing between each tab of the stacked cells, and the contact points are insulated from each other so that each contact forms an independent circuit.

[0035] By passing a probe with this structure through the through-hole of the tab as shown in Figure 6, the contact point of the probe comes into contact with the tab on the upper side in the stacking direction of the cells, and also with the tab on the lower side, so that the contact point of the probe can be pressed against all the tabs at the same time. In addition, since there is no physical contact between the probe and the through-hole shape and the probe that does not match that shape, the occurrence of connection errors can be prevented.

[0036] The probe of the EIS measurement unit is preferably equipped with a spring, as shown in Figure 7. In this case, the battery module is provided with rigid spacers between the tabs of the stacked cells to prevent the tabs from being displaced by the pressure of the probe.

[0037] When the probe is pressed against this tab, which is prevented from displacing, the probe's spring compresses due to the reaction force from the spacer. Therefore, even if there is an error between the distance from the through window to the tab and the length of the probe, this error can be absorbed by the spring, so the probe contact and tab can be easily connected by simply pressing the probe against the tab.

[0038] When installing an EIS measurement unit in a battery module, a recess in which the EIS measurement unit can be placed is provided in the battery module case, and a through-window is formed in this recess, allowing the EIS measurement unit to be flush with the outer surface of the battery module case.

[0039] Because the EIS measurement unit does not protrude from the battery module, it can be prevented from interfering with other components, such as adjacent battery modules.

[0040] The battery module of the present invention can be provided with a lid instead of the EIS measurement unit. If the through-hole in the case is open, foreign matter may enter the battery module. Closing the through-hole with a lid prevents foreign matter from entering and causing the battery module to operate unintentionally.

[0041] The through-window is preferably circular. If the through-window is polygonal, when fitting the lid or EIS measurement unit, depending on the angle, the lid or the like may pass through the through-window and enter the inside of the battery module. However, if the through-window is circular, the lid or the like will not pass through the through-window, improving safety.

[0042] <Battery pack> A battery pack is a single package that contains electrical components such as battery modules, a computer that controls the battery (Electronic Control Unit), a blower that cools the battery, and an EIS measurement unit that measures the battery condition, and is equipped with multiple battery modules.

[0043] As shown in FIG. 8, the battery pack of the present invention is preferably arranged so that the surface on which the through window is formed faces the adjacent battery module.

[0044] When the battery module is arranged in this manner, the probe cannot be inserted through the through-window unless the battery module is removed from the battery pack.

[0045] Therefore, the probe cannot be inserted while the battery module is assembled in the battery pack, i.e., while the battery module is connected to a high-voltage line, improving safety during measurement.

[0046] It is not necessary that the through windows of all battery modules be provided on the surface facing the adjacent battery module; for example, the battery modules at the ends may be positioned so that a probe cannot be inserted when assembled, due to the outer casing of the battery pack, etc. [Explanation of symbols]

[0047] 1 Battery Module 1a Adjacent battery module 2 cases 21 Through window 22 recess 3 cells 31a Positive electrode tab 31b Negative electrode tab 310 Through hole 4 EIS measurement unit 41 Probe 410 contacts 5 spacers 6 springs

Claims

1. A battery module in which a plurality of stacked cells are housed in a case, the case has at least one through window; the tabs of the plurality of cells are flat; the through window is provided on a surface of the tab opposite to the main surface, a battery module, wherein each of the tabs of the plurality of cells is provided at a position visible from the stacking direction of the cells through the through window.

2. 2. The battery module according to claim 1, wherein the tabs of the plurality of cells are offset from one another in a direction perpendicular to the stacking direction of the cells.

3. The through window is provided with an EIS measurement unit, The EIS measurement unit has a plurality of probes, 3. The battery module according to claim 2, wherein the plurality of probes are in contact with different tabs.

4. the tabs of the plurality of cells are arranged side by side at positions overlapping in the stacking direction of the cells, the tab has a through hole; 2. The battery module according to claim 1, wherein the through holes are arranged at positions where a through hole provided in a tab on a lower side in the stacking direction of the cells overlaps with a through hole provided in a tab on the upper side, and the lower through hole is smaller than the upper through hole.

5. The through window is provided with an EIS measurement unit, 5. The battery module according to claim 4, wherein the probe of the EIS measurement unit abuts against an upper tab in the stacking direction of the cells and also abuts against a lower tab through a through-hole in the tab.

6. spacers are provided between the tabs in the stacking direction of the cells; 6. The battery module according to claim 3, wherein the probe has a spring and receives a reaction force from the spacer to come into contact with the tab.

7. the case has a recess, 7. The battery module according to claim 3, wherein the through window is provided in the recess, and the EIS measurement unit and the outer surface of the case are flush with each other.

8. 5. The battery module according to claim 1, wherein the through-window has a cover.

9. The battery module according to claim 7, wherein the through window is circular.

10. A battery pack containing a plurality of battery modules, A battery pack, wherein the battery module is the battery module according to any one of claims 1 to 9, and the through window is provided on a surface facing an adjacent battery module.

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