JP2013222671A - Secondary battery, secondary battery system, and method for controlling the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the degree of safety in a secondary battery and a battery system including a secondary battery.SOLUTION: A secondary batty comprises: an electrode group including a positive electrode and a negative electrode; a battery case for accommodating the battery group; a reference electrode installed in the batty case; a voltage sensor; and an external transmission device. The voltage sensor senses the potential difference ΔVP between the positive electrode and the reference electrode and the potential difference ΔVN between the negative electrode and the reference electrode, and the potential difference ΔVP and the potential difference ΔVN sensed by the voltage sensor are wirelessly transmitted to the exterior of the battery case via the external transmission device.

Description

  The present invention relates to a secondary battery, a secondary battery system, and control methods thereof.

  A secondary battery such as a lithium ion secondary battery deteriorates its performance and shortens its life by repeated charging and discharging, but it can be extended by appropriate control. As one of the means, Patent Document 1 discloses a method of detecting a deterioration state of each electrode by installing a reference electrode inside the battery and controlling the lithium ion secondary battery.

JP 2008-276972 A

  In patent document 1, in order to output the information of the reference electrode installed inside the battery to the outside, a reference electrode measurement terminal must be added. For this reason, the number of connection parts increases due to the addition of a joint member. Therefore, there is a problem in safety as a result of an increase in the possibility of electrolyte leakage. An object of the present invention is to improve safety in a secondary battery having a battery electrode state detection function and a battery system having the secondary battery.

The features of the present invention for solving the above problems are as follows, for example.
A secondary battery having an electrode group having a positive electrode and a negative electrode, a battery case for housing the electrode group, a reference electrode installed in the battery case, a voltage sensor, and an external transmitter, A secondary battery in which a potential difference ΔVP between the positive electrode and the reference electrode and a potential difference ΔVN between the negative electrode and the reference electrode are detected, and the potential difference ΔVP and the potential difference ΔVN detected by the voltage sensor are wirelessly transmitted to the outside of the battery case via the external transmitter. .

  In the above, a secondary battery in which an electrolyte is contained in the secondary battery, and the reference electrode, the voltage sensor, and the external transmission device are coated with resin.

  In the above, the secondary battery in which the potential difference ΔVP and the potential difference ΔVN detected by the voltage sensor are transmitted by optical radio to the outside of the battery case via the external transmission device.

  In the above, the external transmission device is an LED light, the lithium ion secondary battery has a negative electrode terminal, a battery cover, and a gasket, the negative electrode terminal and the battery cover are insulated by the gasket, and the LED light is formed near the gasket. Secondary battery.

  In the above, the LED light is a secondary battery attached to the battery lid.

  In the above, the external transmission device is a piezoelectric speaker, and the potential difference ΔVP and the potential difference ΔVN detected by the voltage sensor are transmitted to the outside of the battery case via the external transmission device, and the piezoelectric speaker is attached to the battery case. Secondary battery.

  In the above, the secondary battery in which the potential difference ΔVP and the potential difference ΔVN detected by the voltage sensor are transmitted by electromagnetic waves to the outside of the battery case via the external transmitter, and the battery case is formed of resin.

  A secondary battery system comprising the above secondary battery, wherein a receiver for intercepting the potential difference ΔVP and the potential difference ΔVN transmitted wirelessly outside the battery case, and electronic control for controlling the amount of current to the secondary battery A secondary battery system in which the electronic control unit controls the amount of charge to the secondary battery when the potential difference ΔVN is equal to or less than a predetermined value or when the potential difference ΔVP is equal to or greater than the predetermined value.

  A secondary battery system having a secondary battery having an electrode group having a positive electrode and a negative electrode, a battery case for housing the electrode group, a reference electrode installed in the battery case, a voltage sensor, and an external transmitter. The potential difference ΔVP between the positive electrode and the reference electrode and the potential difference ΔVN between the negative electrode and the reference electrode are detected by the voltage sensor, and the potential difference ΔVP and the potential difference ΔVN detected by the voltage sensor are transmitted to the battery case via the external transmitter. A secondary battery system that is wirelessly transmitted to the outside includes a receiver that intercepts the potential difference ΔVP and the potential difference ΔVN that is wirelessly transmitted to the outside of the battery case, an electronic control unit that controls the amount of current to the secondary battery, When the potential difference ΔVN is equal to or smaller than a predetermined value, or the potential difference ΔVP is equal to or larger than the predetermined value, the electronic control unit controls the amount of charge to the secondary battery. Control method of secondary battery system.

  According to the present invention, safety can be improved in a secondary battery having a battery electrode state detection function and a battery system having the secondary battery. Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

It is the schematic of the lithium ion secondary battery which shows the structure in one Embodiment of this invention. It is the schematic of the microcomputer inside a lithium ion secondary battery. FIG. 3 is a schematic diagram of an electrolytic solution anti-corrosion measure in an electronic circuit inside a lithium ion secondary battery. FIG. 3 is a schematic diagram of an electrolytic solution anti-corrosion measure in an electronic circuit inside a lithium ion secondary battery. It is the schematic of a lithium ion secondary battery when an external transmission device is a piezoelectric speaker. It is the schematic of a lithium ion secondary battery when an external transmitter is an LED light. It is an enlarged view near the terminal of the lithium ion secondary battery when the external transmitter is an LED light. It is a circuit diagram of the battery system which has a lithium ion secondary battery which shows the structure in one Embodiment of this invention. 6 is a flowchart for controlling a lithium ion secondary battery in the battery system of FIG. 5. 6 is a flowchart for controlling a lithium ion secondary battery in the battery system of FIG. 5. 6 is a flowchart for controlling a lithium ion secondary battery in the battery system of FIG. 5.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following description shows specific examples of the contents of the present invention, and the present invention is not limited to these descriptions. Various modifications by those skilled in the art are within the scope of the technical idea disclosed in this specification. Changes and modifications are possible. In all the drawings for explaining the present invention, components having the same function are denoted by the same reference numerals, and repeated description thereof may be omitted.

  FIG. 1 is a schematic view of a lithium ion secondary battery showing a configuration in an embodiment of the present invention. Below, a lithium ion secondary battery is demonstrated as a secondary battery.

  A single cell in which a positive electrode 4, a separator 6, and a negative electrode 5 are sequentially stacked, and a reference electrode 7 are installed and configured in a battery case 11. The positive electrode terminal 2 and the negative electrode terminal 3 are electrically connected to the positive electrode 4 and the negative electrode 5 through the positive electrode tab and the negative electrode tab, respectively, and the lithium ion secondary battery 1 is charged and discharged by an external circuit through the positive electrode terminal 2 and the negative electrode terminal 3. .

  The single cell portion has a configuration in which the positive electrode 4, the separator 6, the negative electrode 5, and the separator 6 are alternately overlapped and wound. The shape of the battery includes a wound cylindrical shape, a flat oval shape, a wound square shape, and a laminated shape, and any shape may be selected. The reference electrode 7 is covered with a polyolefin-based resin sheet that is used for the separator, and neither the positive electrode 4 nor the negative electrode 5 has electrical conductivity.

The positive electrode 4 of the lithium ion secondary battery 1 shown in FIG. 1 includes a positive electrode active material made of a lithium-containing oxide capable of reversibly inserting and removing lithium ions. As the positive electrode active material, for example, lithium nickel oxide LiNiO ₂ or lithium cobalt oxide LiCoO _2, and the like lithium manganate LiMn ₂ O _4. In the positive electrode active material in the positive electrode 4, lithium ions are desorbed in the charging process, and lithium ions desorbed from the negative electrode active material in the negative electrode 5 are inserted in the discharging process.

  The negative electrode 5 includes a negative electrode active material made of a carbon material that can reversibly insert and desorb lithium ions. As negative electrode active material, raw material is natural graphite, composite carbonaceous material in which a film is formed on natural graphite by dry CVD method or wet spray method, resin material such as epoxy or phenol, or pitch material obtained from petroleum or coal Artificial graphite produced by firing, silicon (Si), graphite mixed with silicon, non-graphitizable carbon material, and the like can be used. The above materials may be contained singly or in combination of two or more as the negative electrode active material. In the negative electrode active material in the negative electrode 5, lithium ions desorbed from the positive electrode active material in the positive electrode 4 are inserted in the charging process, and lithium ions are desorbed in the discharging process.

  For example, a separator 6 made of polypropylene is used between the positive electrode 4 and the negative electrode 5. In addition to polypropylene, the separator 6 may be a microporous film made of polyolefin such as polyethylene or a nonwoven fabric. The thickness of the separator 6 is preferably 20 μm or less, and more preferably 18 μm or less. By using the separator 6 having such a thickness, the capacity per volume of the battery can be increased. However, if the separator 6 is made too thin, the handleability is impaired, or the separation between the positive electrode 4 and the negative electrode 5 is insufficient, and a short circuit is likely to occur. Therefore, the lower limit of the thickness of the separator 6 is 10 μm. Preferably there is.

  The positive electrode 4, the separator 6, the negative electrode 5, and the separator 6 are superposed in this order and wound to form an electrode group. Further, the reference electrode 7 is installed so as to be in contact with the positive electrode 4 and the negative electrode 5 of the electrode group covered with the separator 6. This is stored and inserted in the battery case 11. The reference electrode 7 is in contact with the electrolytic solution, and is disposed in a non-contact manner with the positive electrode 4 and the negative electrode 5. The reference electrode 7 is used as a reference electrode for detecting the potentials of the positive electrode 4 and the negative electrode 5 with respect to the standard potential of the metallic lithium.

  As an electrolytic solution that is an electrolyte, for example, a non-aqueous solution in which 1 mol / l of lithium hexafluorophosphate is dissolved in a mixed solvent of ethylene carbonate and diethyl carbonate having a volume ratio of 1: 1 is injected into the battery case 11.

The lithium salt is not particularly limited, but for inorganic lithium salts, LiPF ₆ , LiBF ₄ , LiClO ₄ , LiI, LiCl, LiBr, etc., and for organic lithium salts, LiB [OCOCF ₃ ] ₄ , LiB [OCOCF ₂ CF ₃ ] ₄ , LiPF ₄ (CF ₃ ) ₂ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ CF ₂ CF ₃ ) _2, or the like can be used.

  As the solvent, an aprotic organic solvent such as ethylene carbonate (EC), dimethyl carbonate (DMC), propylene carbonate, or a solvent of two or more mixed organic compounds is used. Lithium ion secondary batteries have good discharge characteristics during charge / discharge cycles, low temperature and high current discharge characteristics, long-term storage, and long-term high-temperature storage characteristics. Therefore, there is a demand for an organic electrolyte that satisfies these requirements. In order to satisfy the above various requirements, it is difficult to use a solvent composed of only one kind of compound, and it is necessary to mix two or more kinds of compounds and use them as a solvent.

  Specifically, for example, ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC) and the like that improve the dissociation degree of the lithium salt and improve the ionic conductivity can be mentioned. Of these, EC is preferred because it has the highest dielectric constant, can improve the dissociation degree of the lithium salt, and can provide a highly ionic conductive electrolyte. Dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC) and the like can be used.

  When using a solid polymer electrolyte (polymer electrolyte) in addition to the electrolyte as the electrolyte, ion-conducting polymers such as polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, polyhexafluoropropylene, and polyethylene oxide are used as the electrolyte. Can be used. When these solid polymer electrolytes are used, there is an advantage that the separator 6 can be omitted.

  In the battery case 11, a voltage sensor 8, a microcomputer 9, and an external transmission device 10 are provided, and the potential difference ΔVP between the positive electrode 4 and the reference electrode 7 and the negative electrode 5 and the reference electrode 7 are detected by the voltage sensor 8 inside the battery. The potential difference ΔVN is detected, and the information is transmitted to the outside by the wireless communication function of the external transmission device 10. The voltage sensor 8, the microcomputer 9, and the external transmission device 10 do not have a connection terminal with an electronic control unit provided outside the battery case 11. Thereby, a connection site | part increases by adding a coupling member, and it can suppress that the possibility of electrolyte solution rises.

  The voltage sensor 8 detects a potential difference ΔVP between the positive electrode 4 and the reference electrode 7 and a potential difference ΔVN between the negative electrode 5 and the reference electrode 7, and is connected to the positive electrode 4, the negative electrode 5, and the reference electrode 7 through wiring.

  As a communication means of the external transmission device 10, communication using electromagnetic waves is typical, but communication using light and sound waves can also be used. Each communication means has a characteristic, and the appropriate location of the voltage sensor 8, the microcomputer 9, and the external transmission device 10 is different. Details of this point will be described later.

  FIG. 2 shows a simple schematic diagram inside the microcomputer 9. The microcomputer 9 is connected to the voltage sensor 8 and the external transmission device 10 by wiring, and the inside of the microcomputer 9 includes an A / D converter 12, a FlashRom 13, and an IC 14. The potential difference ΔVP between the positive electrode 4 and the reference electrode 7 detected by the voltage sensor 8 and the potential difference ΔVN between the negative electrode 5 and the reference electrode 7 are converted from an analog signal to a digital signal by the A / D converter 12 and recorded in the FlashRom 13. . The digital data transmitted to the FlashRom 13 is transferred to the external transmission device 10 as needed, and the digital data is transmitted from the external transmission device 10 to the outside. These series of operations are controlled by the IC 14.

  Since the non-aqueous electrolyte is injected into the lithium ion secondary battery 1, anticorrosion processing is necessary to install an electronic circuit including the voltage sensor 8, the microcomputer 9, and the external transmitter 10. If the electronic circuit is brought into contact with the non-aqueous electrolyte without performing anticorrosion processing, the electronic circuit may not only malfunction due to the electrolyte, but the electrolyte may ignite due to heat generation of the conductive wiring through which current flows. As the anticorrosion process, as shown in FIG. 3A, the surface of the electronic circuit is formed with a resin film having excellent insulation and chemical resistance against the electrolytic solution. Examples of the resin for surface coating processing used for the coating 15 include polyparaxylene resin and fluororesin, but fluororesin is used because of its strong chemical resistance to hydrofluoric acid which is a by-product of the electrolytic solution. It is most desirable.

  Further, as shown in FIG. 3B, main electronic circuits such as the voltage sensor 8 and the microcomputer 9 are incorporated in a resin box 16 such as polycarbonate, and only the wiring and the external transmitter 10 are resin-coated. Good. By using the resin box 16, the cost can be reduced as compared with the case where the coating 15 is formed on the entire electronic circuit.

  By connecting the electrode group to a device other than the voltage sensor 8, electrode information other than potential difference information can be transmitted to the outside. For example, by connecting thermocouples to the outer peripheral side and inner peripheral side of the electrode group and transmitting the information to the microcomputer 9, temperature information for each part of the electrode can be transmitted to the outside via the external transmitter 10. Is possible. Further, by connecting a surface thickness sensor to each part of the electrode group and transmitting the information to the microcomputer 9, it is also possible to transmit temperature information for each part of the electrode to the outside via the external transmission device 10. .

  A typical example of the external transmission device 10 is a wireless transmission device that uses electromagnetic waves as communication means. The digital information converted by the A / D converter 12 is transmitted on the electromagnetic wave emitted by the wireless transmission device and transmitted outside the battery. These series of operations are controlled by the IC 14.

  When electromagnetic waves are used for the communication means, if the battery case 11 of the lithium ion secondary battery 1 is made of metal, the electromagnetic wave may be shielded by the metal case and the digital signal may not be transmitted to the outside. 11 is preferably made of resin such as polycarbonate.

  When the battery case 11 is made of a resin such as polycarbonate, the location of the external transmission device 10 can be placed anywhere as long as there is a space in the battery case 11, but the intensity of received electromagnetic waves can be increased. In order not to decrease, it is desirable to place the battery case 11 in close contact. When the battery case 11 is placed in close contact with the battery case 11, whether or not to attach to the battery case 11 is not particularly limited, but it is preferable to attach to the battery case 11 in consideration of stability. The arrangement location of the voltage sensor 8 and the microcomputer 9 is not particularly limited, but it is preferable that the voltage sensor 8 and the microcomputer 9 are also attached to the battery case 11 in consideration of stability.

  Next, a case where a wireless transmission device that uses sound waves as communication means is used as the external transmission device 10 will be described. FIG. 4A shows a schematic view thereof.

  When sound waves are used for the communication means, it is possible to use a piezoelectric speaker using a piezoelectric element. The wavelength of the sound wave is not limited, and an ultrasonic wave may be used even at a low wavelength. The piezoelectric element has a structure based on an element in which a piezoelectric body is sandwiched between two electrodes. Ceramics with a perovskite structure such as barium titanate and Rochelle salt (potassium sodium tartrate) are often used as piezoelectric materials, but the sensitivity of piezoelectric elements using Rochelle salt is very high, and the output voltage is high. Since it is very small, a piezoelectric speaker using Rochelle salt as a piezoelectric material is desirable.

  When sound waves are used for the communication means, the material of the battery case 11 can be used regardless of whether it is made of metal or resin.

  The piezoelectric speaker 17 may be placed anywhere in the battery case 11 as long as there is a space. However, in order not to reduce the intensity of the received electromagnetic wave, the piezoelectric speaker 17 is placed in close contact with the battery case 11. Is desirable. When the battery case 11 is placed in close contact with the battery case 11, whether or not to attach to the battery case 11 is not particularly limited, but it is preferable to attach to the battery case 11 in consideration of stability. The arrangement location of the voltage sensor 8 and the microcomputer 9 is not particularly limited, but it is preferable that the voltage sensor 8 and the microcomputer 9 are also attached to the battery case 11 in consideration of stability.

  The acquired electrode data is converted by the A / D converter 12, and the digital information is transmitted on the sound wave emitted by the piezoelectric speaker 17 and transmitted to the outside of the lithium ion secondary battery 1. These series of operations are controlled by the IC 14.

  Next, a case where a wireless transmission device using light as a communication means is used as the external transmission device 10 will be described. FIG. 4B shows a schematic diagram thereof.

  When light is used for the communication means, the external transmitter 10 is externally connected by optical wireless communication using visible light using an LED light, an organic EL, a laser, or the like, or by infrared optical wireless communication using an infrared device for the external transmitter 10. Send information. Either visible light or infrared light may be used as the communication means, but since visible light communication has a high transmission speed, it is desirable to use visible light communication using an LED light or the like.

  When light is used for the communication means, the material of the battery case 11 can be used regardless of the material made of metal or resin. When the LED light is used, the LED light is preferably disposed near the gasket used for insulation near the terminal.

  FIG. 4C shows a diagram when the LED light 18 is arranged near the negative electrode terminal 3 as an example. 4C, the negative electrode terminal 3, the gasket 19, the battery lid 20, the insulating plate 21, and the terminal plate 22 are crimped. The negative electrode terminal 3 and the terminal plate 22 are energized, and the terminal plate 22 is bonded to the negative electrode tab 23 to energize the negative electrode terminal 3 and the negative electrode 5. The gasket 19 has a role of insulating the negative electrode terminal 3 and the battery cover 20 and sealing the battery, and an insulating plate 21 has a role of insulating the battery cover 20 and the terminal plate 22.

  The reason why the LED light 18 is disposed in the vicinity of the gasket 19 is that the battery case 11 cannot transmit light of the LED light 18 regardless of whether it is made of metal or resin, but the gasket 19 is transparent to transmit light. This is because there are various materials. Since the gasket 19 transmits light, it is desirable to use a transparent material such as a fluororesin PFA.

  The detailed arrangement place of the LED light 18 may be any place where the light emitted from the LED light 18 can pass through the gasket 19. Examples of the attachment method include embedding in the gasket 19 and attaching to the surface of the battery lid 20. However, considering the assembly process, it is more preferable because it is easier to attach to the battery lid 20.

  Although it depends on the battery structure, the LED light 18 may be arranged not near the negative electrode terminal 3 but near the positive electrode terminal 2. You may arrange | position the LED light 18 to both the negative electrode terminal 3 and the positive electrode terminal 2. FIG.

  Although the location of the voltage sensor 8 and the microcomputer 9 is not particularly limited, it is preferable that the voltage sensor 8 and the microcomputer 9 are attached to the battery case 11 in consideration of stability.

  The acquired electrode data is transmitted to the outside of the battery by placing the digital information converted by the A / D converter 12 on the light emitted by the LED light 18. These series of operations are controlled by the IC 14.

  As a method for transmitting the electrode information to the outside, there are a PLC communication method and a method for transmitting the electrode information by adding a digital signal to the AC signal.

  Next, a lithium ion secondary battery 1 according to an embodiment of the present invention and a battery system using the lithium ion secondary battery 1 will be described. Here, the battery system refers to an assembled battery in which a plurality of lithium ion secondary batteries including the lithium ion secondary battery 1 are connected in series or in parallel. As an embodiment of the present invention, a system in which a plurality of lithium ion secondary batteries including the lithium ion secondary battery 1 are connected in series will be described.

  FIG. 5 is a block diagram showing the basic configuration of the charge / discharge control system of one embodiment of the lithium ion secondary battery 1 of the present invention. FIG. 5 shows a lithium ion secondary battery 1 having a positive electrode terminal 2 connected to a positive electrode 4 and a negative electrode terminal 3 connected to a negative electrode 5, and reception for intercepting digital data transmitted from the inside of the lithium ion secondary battery 1. The electronic control unit 25 that controls the amount of current to the lithium ion secondary battery 1, and a power supply circuit 26 that is a power source of the electronic control unit 25. The electronic control unit 25 analyzes the electrode information transferred from the receiver 24 to determine whether the electrode state satisfies the set condition, the FlashRom 13 that stores the received electrode information, and the determination unit 27. The control unit 28 is configured to control the amount of current supplied to the lithium ion secondary battery 1 by the signal transmitted by. A circuit for supplementary charging of the lithium ion secondary battery 1 is also incorporated from the control unit 28 in the electronic control unit 25.

  A lithium ion secondary battery 1 according to an embodiment of the present invention obtains a power source for an electronic device including an internal voltage sensor 8, a microcomputer 9, and an external transmitter 10 from an electrode group of the lithium ion secondary battery 1. Therefore, the capacity of the lithium ion secondary battery 1 may be reduced as compared with a lithium ion secondary battery in which the external transmission device 10 is not installed. Therefore, it is necessary to supplementarily charge the lithium ion secondary battery 1 from the electronic control unit 25 by the amount of electricity used by the electronic device.

  The amount of electricity consumed by the voltage sensor 8, the microcomputer 9, and the external transmission device 10 is proportional to the device usage time. The amount of electricity consumed per unit time can be estimated from the capacity difference between the lithium ion secondary battery having no external transmitter 10 and the lithium ion secondary battery having the external transmitter 10. The electronic control unit 25 performs supplementary charging through an electric circuit between the control unit 28 and the lithium ion secondary battery 1 having the external transmitter 10.

  Next, FIG. 6 is a flowchart for explaining a control structure for suppressing deterioration of the lithium ion secondary battery 1 in the battery system according to the embodiment of the present invention shown in FIG. The process shown in this control flowchart is called from the main routine and executed at regular intervals.

  The principle of the lithium ion secondary battery is that charge / discharge reaction proceeds when lithium ions in the electrolyte are inserted into and desorbed from the electrode active material. When the lithium ion secondary battery is overcharged, lithium in the active material is excessively desorbed in the positive electrode 4, the crystal structure becomes unstable and deteriorates, and the battery performance may be lowered. In addition, in the negative electrode 5, when the voltage is 0 V or less, there is a risk that lithium metal is dendrited and the battery is short-circuited. In addition, depending on the material used for the negative electrode 5, the crystal structure may collapse due to a voltage lower than a certain voltage, which may reduce the battery life.

  Therefore, in the flowchart of FIG. 6, the potential of the negative electrode 5 with respect to the reference potential possessed by the metallic lithium is measured by detecting the potential difference ΔVN between the negative electrode 5 and the reference electrode 7, and the potential difference ΔVN> 0 when the potential difference ΔVN ≦ 0. Thus, the charge amount to the lithium ion secondary battery 1 is suppressed so that the potential of the negative electrode 5 becomes higher than the potential of the reference electrode 7.

  In the flowchart of FIG. 6, the maximum potential A of the positive electrode 4 capable of preventing the crystal structure collapse of the positive electrode 4 is defined in advance, and a predetermined value A indicating the potential difference between the positive electrode 4 and the reference electrode 7 is When the potential difference ΔVP with respect to the reference electrode 7 becomes greater than or equal to the reference electrode 7, the charge amount of the lithium ion secondary battery 1 is suppressed so that the potential difference ΔVP becomes smaller than the specified value A. In the negative electrode 5 as well, when the negative electrode material described above is used, a potential B at which the crystal structure of the negative electrode material obtained by measurement in advance is collapsed and the potential difference ΔVP between the negative electrode 5 and the reference electrode 7 is positive. When the voltage difference between the reference voltage 7 and the reference electrode 7 becomes equal to or less than the specified value B, the charging amount of the lithium ion secondary battery 1 is suppressed so that the potential difference ΔVP becomes larger than the specified value B. .

  The electrode information transmitted from the external transmitter 10 in the lithium ion secondary battery 1 is output to the electronic control unit 25 via the receiver 24. In the electrode information analyzed in the electronic control unit 25, the lithium ion secondary battery 1 is charged, and the potential difference ΔVP between the positive electrode 4 and the reference electrode 7 and the potential difference ΔVN between the negative electrode 5 and the reference electrode 7 are described later. By satisfying the above condition, the determination unit 27 in the electronic control unit 25 issues a command to the control unit 28 to control the amount of charge to the lithium ion secondary battery.

  The control flowchart of FIG. 6 will be described with reference to FIG.

<Step S1>
First, the determination unit 27 determines whether or not the lithium ion secondary battery 1 is being charged. If it is determined that the battery is not being charged (NO in step S1), the process proceeds to step S6. If it is determined in step S1 that lithium ion secondary battery 1 is being charged (YES in step S1), the process proceeds to step S2.

<Step S2>
The determination unit 27 detects the potential difference ΔVP between the positive electrode 4 and the reference electrode 7 and the potential difference ΔVN between the negative electrode 5 and the reference electrode 7.

<Step S3>
Next, the determination unit 27 first determines whether or not the potential difference ΔVN is 0 or larger than the specified value B. That is, it is determined whether or not the potential of the negative electrode 5 is higher than the reference potential of metallic lithium. If it is determined that potential difference ΔVN is 0 or less (NO in step S3), the process proceeds to step S5. If it is determined in step S3 that the potential difference ΔVN is greater than 0 or greater than the specified value B (0 if the specified value is 0) (YES in step S3), the process proceeds to step S4. Transition.

<Step S4>
The determination unit 27 determines whether or not the potential difference ΔVP is smaller than the specified value A (step S4). Then, if it is determined that potential difference ΔVP is equal to or greater than specified value A (NO in step S4), the process proceeds to step S5. On the other hand, if it is determined in step S4 that potential difference ΔVP is smaller than specified value A (YES in step S4), the process proceeds to step S6.

<Step S5>
In order to prevent metallic lithium from being deposited on the negative electrode 5, the determination unit 27 issues a command to the control unit 28 to control the amount of charge to the lithium ion secondary battery 1. In addition, for the purpose of preventing the cathode 4 from crystal collapse, the determination unit 27 issues a command to the control unit 28 to suppress the amount of charge to the lithium ion secondary battery 1.

  As described above, in this embodiment, the reference electrode 7 made of metallic lithium is provided, and the potential difference ΔVP between the positive electrode 4 and the reference electrode 7 and the potential difference ΔVN between the negative electrode 5 and the reference electrode 7 are detected. When the potential difference ΔVN is negative or when the potential difference ΔVP is equal to or greater than the specified value A, the charge amount to the lithium ion secondary battery 1 is suppressed.

  Therefore, according to one embodiment of the present invention, in the lithium ion secondary battery 1, deposition of metallic lithium and the positive electrode in the negative electrode 5 can be performed without adding a reference electrode measurement terminal (without increasing the joint portion). 4 crystal collapse can be prevented. As a result, safety can be improved in a lithium ion secondary battery having a battery electrode state detection function using the reference electrode 7 and a battery system having the secondary battery.

  As configurations other than the flowchart of FIG. 6, there are a configuration in which only the potential difference ΔVN is considered as in the flowchart of FIG. 7 and a configuration in which only the potential difference ΔVP is considered as in the flowchart of FIG. 8.

  The lithium ion secondary battery having a battery electrode state detection function and the battery system having the secondary battery of the present invention are produced by an in-vehicle power storage system used in plug-in hybrid vehicles and electric vehicles, and by power generation. It can be applied to a stationary power storage system for temporarily storing the generated power.

DESCRIPTION OF SYMBOLS 1 Lithium ion secondary battery 2 Positive electrode terminal 3 Negative electrode terminal 4 Positive electrode 5 Negative electrode 6 Separator 7 Reference electrode 8 Voltage sensor 9 Microcomputer 10 External transmitter 11 Battery case 12 A / D converter 13 FlashRom
14 IC
15 Coating 16 Resin Box 17 Piezoelectric Speaker
18 LED light 19 Gasket
20 Battery cover 21 Insulation plate
22 Terminal board 23 Negative electrode tab 24 Receiver 25 Electronic control unit 26 Power supply circuit 27 Determination unit 28 Control unit

Claims (9)

An electrode group having a positive electrode and a negative electrode;
A battery case for housing the electrode group;
A secondary battery having a reference electrode installed in the battery case, a voltage sensor, and an external transmitter,
The voltage sensor detects a potential difference ΔVP between the positive electrode and the reference electrode, and a potential difference ΔVN between the negative electrode and the reference electrode,
A secondary battery in which the potential difference ΔVP and the potential difference ΔVN detected by the voltage sensor are wirelessly transmitted to the outside of the battery case via the external transmission device. In claim 1,
The secondary battery includes an electrolyte,
A secondary battery in which the reference electrode, the voltage sensor, and the external transmitter are coated with resin. In claim 1 or 2,
A secondary battery in which the potential difference ΔVP and the potential difference ΔVN detected by the voltage sensor are transmitted by optical radio to the outside of the battery case via the external transmitter. In claim 3,
The external transmitter is an LED light,
The lithium ion secondary battery has a negative electrode terminal, a battery lid, and a gasket,
The negative electrode terminal and the battery lid are insulated by the gasket,
The LED light is a secondary battery formed near the gasket. In claim 3 or 4,
The LED light is a secondary battery attached to the battery lid. In claim 1 or 2,
The external transmitter is a piezoelectric speaker;
The potential difference ΔVP and the potential difference ΔVN detected by the voltage sensor are transmitted to the outside of the battery case via the external transmission device by sonic radio waves,
The piezoelectric speaker is a secondary battery attached to the battery case. In claim 1 or 2,
The potential difference ΔVP and the potential difference ΔVN detected by the voltage sensor are transmitted as electromagnetic waves to the outside of the battery case via the external transmission device,
The battery case is a secondary battery formed of resin. A secondary battery system comprising the secondary battery according to claim 1,
A receiver for intercepting the potential difference ΔVP and the potential difference ΔVN transmitted wirelessly outside the battery case;
An electronic control unit for controlling the amount of current to the secondary battery,
When the potential difference ΔVN is equal to or less than a predetermined value, or when the potential difference ΔVP is equal to or greater than a predetermined value, the electronic control unit controls a charge amount of the secondary battery. An electrode group having a positive electrode and a negative electrode;
A battery case for housing the electrode group;
A control method of a secondary battery system having a secondary battery having a reference electrode installed in the battery case, a voltage sensor, and an external transmitter,
The voltage sensor detects a potential difference ΔVP between the positive electrode and the reference electrode, and a potential difference ΔVN between the negative electrode and the reference electrode,
The potential difference ΔVP and the potential difference ΔVN detected by the voltage sensor are wirelessly transmitted to the outside of the battery case via the external transmission device,
The secondary battery system includes a receiver that intercepts the potential difference ΔVP and the potential difference ΔVN transmitted wirelessly outside the battery case;
An electronic control unit for controlling the amount of current to the secondary battery,
When the potential difference ΔVN is equal to or smaller than a predetermined value, or when the potential difference ΔVP is equal to or larger than a predetermined value, the electronic control unit controls a secondary battery system that controls a charge amount of the secondary battery.