Energy storage device

Abstract

To reduce the false detection rate of a pressure sensor in a structure that detects the pressure inside the outer casing using a pressure sensor. [Solution] The energy storage device comprises an energy storage module, a laminated casing that houses the energy storage module in a reduced internal pressure state, a pressure detection unit provided inside the laminated casing that detects the internal pressure as a resistance value while in contact with the laminated casing, a temperature detection unit that detects the temperature of the energy storage module, and a control unit that controls the pressure detection unit. The control unit does not perform detection by the pressure detection unit if the temperature of the energy storage module detected by the temperature detection unit is below a predetermined temperature, and performs detection by the pressure detection unit if the temperature of the energy storage module detected by the temperature detection unit is above the predetermined temperature, and determines a correction value based on the temperature of the energy storage module, and corrects the resistance value detected by the pressure detection unit with the correction value.

Description

Technical Field

[0001] The present invention relates to a power storage device.

Background Art

[0002] Patent Document 1 discloses an abnormality detection device arranged in close contact with the outer surface of a battery, which is provided with a pressure sensor that detects a pressure change of a fluid accompanying deformation of the battery, and detects an abnormality of the battery by measuring the deformation of the battery based on the pressure sensor.

Related Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of Invention

Problem to be Solved by the Invention

[0004] Incidentally, a laminate-type battery has a structure in which a power storage module is housed inside an exterior body. Although the power storage module housed in the exterior body is restrained by the decompression force of atmospheric pressure, the inside of the exterior body is repressurized due to the vapor pressure and gas generation inside the power storage module. Since the battery performance is affected when the inside of the exterior body is repressurized, a method of detecting the repressurization with a pressure-sensitive sensor when the internal pressure rises to a specified pressure is known. However, the detection timing becomes earlier due to the influence of accuracy variation of the pressure-sensitive sensor, and as a result, the detection rate increases, leading to an increase in the false detection rate.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a power storage device capable of reducing the false detection rate of a pressure-sensitive sensor in a structure that detects the pressure inside an exterior body by the pressure-sensitive sensor.

Means for Solving the Problem

[0006] The present invention comprises a power storage module, a laminated casing that houses the power storage module in a reduced-pressure state, a pressure detection unit provided inside the laminated casing and detecting the internal pressure as a resistance value in contact with the laminated casing, a temperature detection unit that detects the temperature of the power storage module, and a control unit that controls the pressure detection unit. The control unit is characterized in that, if the temperature of the power storage module detected by the temperature detection unit is below a predetermined temperature, it does not perform detection by the pressure detection unit, and if the temperature of the power storage module detected by the temperature detection unit is at or above the predetermined temperature, it performs detection by the pressure detection unit, determines a correction value based on the temperature of the power storage module, and corrects the resistance value detected by the pressure detection unit with the correction value. [Effects of the Invention]

[0007] In this invention, in a structure that detects the pressure inside the outer casing using a pressure-sensitive sensor, the false detection rate of the pressure-sensitive sensor can be reduced. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram showing an energy storage device in an embodiment. [Figure 2] This is a diagram illustrating the placement of pressure sensors. [Figure 3] This diagram illustrates how the energy storage module is confined within the outer casing in a depressurized state. [Figure 4] This diagram shows the relationship between the correction value and temperature. [Figure 5] This is a flowchart illustrating the pressure detection flow. [Modes for carrying out the invention]

[0009] The following describes in detail the energy storage device in the embodiments of the present invention. However, the present invention is not limited to the embodiments described below.

[0010] Figure 1 is a schematic diagram showing an energy storage device in an embodiment. The energy storage device 1 is a bipolar lithium-ion battery. The energy storage device 1 comprises an energy storage module 2, an outer casing 3, a pressure sensor 4, an internal component 5, a temperature sensor 6, and a control unit.

[0011] The energy storage module 2 has an electrode stack in which multiple bipolar electrodes are stacked, and a sealing portion that seals the electrode stack. The energy storage module 2 is formed in a rectangular parallelepiped shape. When the energy storage device 1 is viewed from the stacking direction, the energy storage module 2 is formed in a rectangular shape.

[0012] The outer casing 3 is a laminate that houses the energy storage module 2. The outer casing 3 is made of aluminum laminate. The inside of the outer casing 3 is under vacuum. In addition to the energy storage module 2, the outer casing 3 also houses a pressure sensor 4 and internal components 5.

[0013] The pressure sensor 4 is a pressure detection unit located inside the outer casing 3 that detects the pressure inside the outer casing 3. The pressure sensor 4 is provided inside the outer casing 3, which is in a vacuum state. The pressure sensor 4 is positioned between the internal member 5 and the outer casing 3 in the stacking direction. The pressure sensor 4 has a pressure-sensitive portion on the surface facing the outer casing 3 in the stacking direction. The resistance value of this pressure-sensitive portion changes depending on the contact area.

[0014] The internal component 5 is an insulating resin component. The internal component 5 is positioned opposite the side of the energy storage module 2 and is positioned opposite the outer casing 3 in the stacking direction. It has a flat surface 5a that functions as the top surface.

[0015] As shown in Figure 2, the pressure sensor 4 is installed on the flat surface 5a. The pressure sensor 4 has a pressure-sensitive section arranged along the flat surface 5a. The mounting position of the pressure sensor 4 is not on the top surface of the energy storage module 2, but on the flat surface 5a formed in the internal space of the outer casing 3. This eliminates the influence on the pressure sensor 4 due to deformation of the flat surface of the energy storage module 2, and ensures stable accuracy.

[0016] The pressure-sensitive sensor 4 is capable of measuring from 0 to 100 kPa (absolute pressure). As shown in FIG. 3, the power storage module 2 housed inside the exterior body 3 is restrained by the reduced pressure restraining force from atmospheric pressure. The wiring of the pressure-sensitive sensor 4 is led out to the outside of the exterior body 3 via an FPC. The pressure-sensitive sensor 4 is connected to a control unit via the wiring. The pressure-sensitive sensor 4 is controlled by the control unit.

[0017] The temperature sensor 6 is a temperature detection unit that is arranged outside the exterior body 3 and detects the temperature of the power storage module 2. For example, the temperature sensor 6 is arranged above the power storage module 2 and provided on the outer surface of the exterior body 3. The temperature sensor 6 measures the temperature of the power storage module 2 through the exterior body 3.

[0018] The control unit is a control device that controls the pressure-sensitive sensor 4. The control unit notifies that the inside of the exterior body 3 needs to be depressurized based on the pressure information detected by the pressure-sensitive sensor 4.

[0019] In the power storage device 1, for the purpose of suppressing output variation of the pressure-sensitive sensor 4 due to temperature, the pressure-sensitive sensor 4 is configured not to perform pressure detection until the temperature exceeds a predetermined temperature T1. The control unit performs control so that detection by the pressure-sensitive sensor 4 is not executed until the temperature of the power storage module 2 exceeds the predetermined temperature T1. That is, the detection of the pressure-sensitive sensor 4 is stopped by the control executed by the control unit based on the battery temperature. The predetermined temperature T1 is set to a temperature that exceeds the detection threshold as a theoretical value. The predetermined temperature T1 refers to the detection start temperature. For example, the predetermined temperature T1 is 20 to 40°C.

[0020] In the range where the temperature of the power storage module 2 exceeds the predetermined temperature (on the high temperature side), detection is performed by correcting the resistance correction component caused by the temperature influence on the pressure-sensitive sensor 4 based on the battery temperature detected by the temperature sensor 6. When the temperature of the power storage module 2 exceeds the predetermined temperature, the control unit multiplies the detected value by a correction value based on the temperature characteristics of the pressure-sensitive sensor 4 for determination. The correction value is a different value for each temperature. As shown in FIG. 4, the correction value becomes larger than 1 as the temperature rises.

[0021] Figure 5 is a flowchart showing the pressure detection flow. The control shown in Figure 5 is executed by the control unit.

[0022] The control unit acquires information related to the temperature of the power storage module 2 measured by the temperature sensor 6 (step S1). In step S1, the battery temperature is measured by the temperature sensor 6.

[0023] The control unit determines whether or not the battery temperature is equal to or higher than a predetermined temperature T1 (step S2).

[0024] When it is determined that the battery temperature is not equal to or higher than the predetermined temperature T1 (step S2: No), this control routine returns to step S1. When the temperature of the power storage module 2 detected by the temperature sensor 6 is lower than the predetermined temperature T1, the control unit does not perform detection by the pressure-sensitive sensor 4.

[0025] When it is determined that the battery temperature is equal to or higher than the predetermined temperature T1 (step S2: Yes), the control unit causes the pressure-sensitive sensor 4 to perform detection (step S3). In step S3, the pressure-sensitive sensor 4 starts measurement of the resistance value.

[0026] The control unit determines a correction value based on the battery temperature (step S4). The correction value is determined based on a map having a correlation with temperature as shown in Figure 4.

[0027] The control unit calculates a corrected resistance value obtained by multiplying the resistance value measured by the pressure-sensitive sensor 4 by the correction value (step S5). When the temperature of the power storage module 2 detected by the temperature sensor 6 is equal to or higher than the predetermined temperature T1, the control unit performs detection by the pressure-sensitive sensor 4, determines a correction value based on the temperature of the power storage module 2, and corrects the resistance value detected by the pressure-sensitive sensor 4 with the correction value.

[0028] The control unit determines whether or not the corrected resistance value is equal to or greater than a predetermined resistance value R1 (step S6).

[0029] If it is determined that the corrected resistance value is equal to or greater than a predetermined resistance value R1 (step S6: Yes), the control unit notifies that the inside of the outer casing 3 needs to be depressurized (step S7). After the process in step S7 is completed, this control routine terminates.

[0030] If it is determined that the corrected resistance value is not equal to or greater than the predetermined resistance value R1 (step S6: No), this control routine returns to step S1.

[0031] In the energy storage device 1 configured in this way, the ease with which the outer casing 3 deforms differs depending on the temperature of the energy storage module 2. Therefore, even if the internal pressure of the outer casing 3 is the same, the resistance value detected by the pressure sensor 4 changes depending on the temperature of the energy storage module 2. Since the resistance value is corrected based on the temperature detected by the temperature sensor 6, fluctuations in the resistance value due to temperature can be suppressed.

[0032] As described above, according to the embodiment, it is possible to reduce the false detection rate of the pressure sensor 4.

[0033] Furthermore, because the pressure sensor 4 is positioned between the flat surface 5a and the outer casing 3, rather than on the outer surface of the outer casing 3, the detection accuracy of the pressure sensor 4 is improved.

[0034] Furthermore, as the temperature detected by the temperature sensor 6 increases, the correction value (correction coefficient) gradually increases. This improves the accuracy of the corrected resistance value.

[0035] Furthermore, temperature-dependent corrections may be applied even at lower temperatures. While corrections can cancel out temperature-related offsets, they cannot cancel out variations. Therefore, not detecting temperature variations results in better judgment accuracy.

[0036] Furthermore, in step S7, the control unit may perform control to suppress the pressure rise inside the outer casing 3, such as setting a temperature limit on the energy storage module 2.

[0037] Alternatively, the correction coefficient may be configured to change its sign based on a certain temperature threshold. In this case, the accuracy of the corrected resistance value is improved. [Explanation of Symbols]

[0038] 1. Energy storage device 2 Energy storage modules 3. Exterior 4. Pressure-sensitive sensor 5 Internal components 6. Temperature sensor

Claims

1. Energy storage module and A laminated casing that houses the energy storage module in a depressurized state, A pressure detection unit is provided inside the laminate outer casing and, while in contact with the laminate outer casing, detects the internal pressure as a resistance value. A temperature detection unit for detecting the temperature of the energy storage module, A control unit that controls the pressure detection unit, Equipped with, The control unit, If the temperature of the energy storage module detected by the temperature detection unit is below a predetermined temperature, the pressure detection unit does not perform detection. If the temperature of the energy storage module detected by the temperature detection unit is above the predetermined temperature, the pressure detection unit performs detection, determines a correction value based on the temperature of the energy storage module, and corrects the resistance value detected by the pressure detection unit with the correction value. A power storage device characterized by the following features.

2. The laminated outer casing comprises an internal component provided inside and positioned opposite the side surface of the energy storage module, The pressure detection unit is a pressure-sensitive sensor installed on the flat surface of the internal member. The energy storage device according to feature 1.

3. The pressure sensor has a pressure-sensitive portion sandwiched between the flat portion and the laminated outer casing. The energy storage device according to claim 2.

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