Polarization suppression device for lithium-ion batteries

Abstract

To suppress polarization of a lithium ion battery.SOLUTION: A polarization suppressor for a lithium ion battery 10A includes an AC generating circuit 14A and a control device 15A. The AC generating circuit 14A is connected to positive and negative electrodes of a lithium ion battery 12. The control device 15A controls the AC generating circuit 14A such that an AC current of 100 kHz or higher is applied to the lithium ion battery 12.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a polarization suppression device for a lithium ion battery. [Background technology]

[0002] Lithium ion secondary batteries (hereinafter referred to as lithium ion batteries) have been used as batteries for supplying power to motors of electric vehicles such as electric cars and hybrid cars. Lithium ion batteries are also used in communication devices such as mobile phones and information devices such as personal computers. It is known that lithium ion batteries can become polarized or have lithium precipitated depending on the use.

[0003] Patent Document 1 discloses a configuration in which, when charging a lithium-ion secondary battery, a charging current flowing from the negative electrode to the positive electrode and a reverse pulse current flowing in the opposite direction to the charging current are alternately and repeatedly applied. This configuration is said to be capable of suppressing lithium deposition and periodically dissolving lithium deposited on the negative electrode surface. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-191300 A Summary of the Invention [Problem to be solved by the invention]

[0005] There is a demand for a device that can suppress polarization of a lithium ion battery with a simple configuration.

[0006] An object of the present invention is to provide a device capable of suppressing polarization of a lithium ion battery. [Means for solving the problem]

[0007] The polarization suppression device for a lithium ion battery according to the present invention is characterized in that it comprises an AC generating circuit connected to the positive and negative electrodes of a lithium ion battery, and a control device that controls the AC generating circuit so that an AC current of 100 kHz or more is applied to the lithium ion battery.

[0008] In the polarization suppression device for a lithium ion battery according to the present invention, the AC generating circuit may superimpose the AC current on a DC current when the lithium ion battery is charged or discharged.

[0009] In the polarization suppression device for a lithium ion battery according to the present invention, the control device may control the AC generating circuit so that the amplitude of the AC current is larger when the charging current or discharging current of the lithium ion battery is large compared to when the charging current or discharging current is small.

[0010] In the polarization suppression device for a lithium ion battery according to the present invention, the control device may control the AC generating circuit so that the frequency of the AC current is increased when the charging current or discharging current of the lithium ion battery is large compared to when the charging current or discharging current is small.

[0011] In the polarization suppression device for a lithium ion battery according to the present invention, the control device may control the AC generating circuit so that when the charging current or discharging current of the lithium ion battery is large, the time for which the AC current is applied is increased compared to when the charging current or discharging current is small.

[0012] In the polarization suppression device for a lithium ion battery according to the present invention, the control device may be configured to control the AC generating circuit so that the frequency of application of the AC current is increased when the charging current or discharging current of the lithium ion battery is large compared to when the charging current or discharging current is small.

[0013] In the polarization suppression device for a lithium ion battery according to the present invention, the AC generating circuit may include a series circuit of a coil, a capacitor, and a switching element, and be configured to apply a current of a resonant frequency defined by the series circuit to the lithium ion battery, and the control device may control the on / off of the switching element.

[0014] In the polarization suppression device for a lithium ion battery according to the present invention, the AC generating circuit may be a circuit that applies a current having any one of a sine wave, a square wave, and a triangular wave to the lithium ion battery. Effect of the Invention

[0015] According to the present invention, a high-frequency current of 100 kHz or more can be generated inside a lithium-ion battery. Inside a lithium-ion battery, the high-frequency current flows only to the ends of the positive and negative active materials due to the skin effect, but in an electrolyte solution having a lower conductivity than the active materials, the skin effect is alleviated and the current flows uniformly (or nearly so). At the interface between the active material and the electrolyte solution, the current that flowed at the ends of the active material is diffused in the surface direction and flows uniformly. In other words, a current can be passed in the surface direction at the interface between the active material and the electrolyte solution. Polarization occurs due to the concentration of current density, so by passing a current in the surface direction, polarization can be suppressed. [Brief description of the drawings]

[0016] [Figure 1] 1 is a diagram showing a configuration of a high-frequency generating device according to a first embodiment. [Diagram 2] FIG. 4 is a diagram showing an example of a damped oscillatory current in the high frequency generating device of the first embodiment. [Diagram 3] FIG. 2 is a diagram showing a schematic diagram of the current density inside the battery when a low-frequency current and a high-frequency current flow. [Figure 4] FIG. 11 is a diagram showing a configuration of a high-frequency generating device according to a second embodiment. [Diagram 5] FIG. 13 is a diagram showing a configuration of a high-frequency generating device according to a third embodiment. [Figure 6]FIG. 13 is a diagram showing a configuration of a high-frequency generating device according to a fourth embodiment. [Figure 7] FIG. 1 is a diagram showing an example of a combination of a high-frequency generating device and a charging / discharging device. [Figure 8] FIG. 4 is a diagram showing an example of a battery current. [Figure 9] FIG. 11 is a diagram showing another example of a combination of a high-frequency generating device and a charging / discharging device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Each embodiment of the present invention will be described with reference to each drawing. Note that the present invention is not limited to the embodiment described here. The same components shown in multiple drawings are given the same reference numerals to simplify the description.

[0018] First Embodiment 1 is a diagram showing the configuration of a high frequency generator 10A according to a first embodiment. The high frequency generators according to the first embodiment and other embodiments are devices that apply high frequency current to a lithium ion battery 12 and function as a polarization suppression device for the lithium ion battery 12.

[0019] The high frequency generator 10A may be applied to a lithium ion battery 12 to which no charge / discharge device (power source or load) is connected, or may be applied to a lithium ion battery 12 to which a charge / discharge device 70 is connected as shown in Fig. 7. This also applies to the high frequency generators 10B to 10D (Figs. 4 to 6) of the other embodiments.

[0020] The high frequency generator 10A includes an AC generating circuit 14A and a control device 15A. The AC generating circuit 14A includes an inductor (also called a coil) 20, a capacitor 24, a resistive element 22, and a switching element 26. The switching element 26 is, for example, a metal-oxide-semiconductor field-effect transistor (MOSFET) or an insulated gate bipolar transistor (IGBT). The switching elements of other embodiments may be similar to the switching element 26 of the first embodiment.

[0021] One end of the inductor 20 is connected to the positive electrode of the lithium ion battery 12, and the other end is connected to one end of a capacitor 24. The other end of the capacitor 24 is connected to one end of a switching element 26, and the other end of the switching element 26 is connected to the negative electrode of the lithium ion battery 12. A resistive element 22 is connected in parallel to the capacitor 24. The resistive element 22 connected in parallel to the capacitor 24 is intended to discharge the electric charge stored in the capacitor 24.

[0022] A damped oscillation circuit is formed in a path between the positive and negative electrodes of the lithium ion battery 12 by an inductor 20, a capacitor 24, a resistive element 22, and a switching element 26. The inductor 20, the capacitor 24, and the switching element 26 are connected in series to form a series circuit, and both ends of the series circuit are connected to the positive and negative electrodes of the lithium ion battery 12.

[0023] The control device 15A includes a microcomputer. The microcomputer includes a CPU (Central Processing Unit) that performs arithmetic processing and control processing, memories such as ROM and RAM, and an I / O port (input / output circuit). The control device 15A operates according to control data and programs stored in the memory, and controls the AC generating circuit 14A. Specifically, the control device 15A controls the ON / OFF of the switching element 26 of the AC generating circuit 14A. Note that the control devices 15B to 15D (FIGS. 4 to 6) of other embodiments may also include a similar microcomputer.

[0024] 2 is a diagram showing an example of the damped oscillatory current Ires in the AC generating circuit 14A, where (a) shows the change in the current Ires when the switching element 26 is turned on, and (b) shows the on / off change of the switching element 26 and the change in the current Ires over a longer time period than (a). When the switching element 26 is turned on, as shown in Fig. 2(a), a damped oscillatory current Ires flows from the lithium ion battery 12. Specifically, a damped oscillatory current Ires flows that damps while oscillating at a resonance frequency f (Hz) according to the following (Equation 1).

[0025]

number

[0026] In (Equation 1), L is the inductance (H) of the inductor 20, and C is the capacitance (F) of the capacitor 24. The inductor 20 and the capacitor 24 are selected so that the resonant frequency f (Hz) is 100 kHz or higher. The damping rate of the damped oscillatory current Ires is determined by the L of the inductor 20 and the internal resistance of the lithium ion battery 12.

[0027] 2(b), the control device 15A controls the switching element 26 to be repeatedly conductive in a pulsed manner. Here, the control to be conductive in a pulsed manner refers to control to change the switching element 26 from off to on, maintain the on state for a predetermined time, and then change it from on to off.

[0028] Next, the effects of the high frequency generating device 10A described above will be described.

[0029] According to the high frequency generator 10A described above, a high frequency current of 100 kHz or more is generated inside the lithium ion battery 12. Fig. 3(a) is a diagram showing the current density inside the battery when a low frequency current flows, and Fig. 3(b) is a diagram showing the current density inside the battery when a high frequency current flows. As shown in Fig. 3(a), when a direct current or a low frequency current flows inside the battery, the current flows uniformly or nearly uniformly in the positive electrode, the negative electrode, and the electrolyte.

[0030] On the other hand, as shown in FIG. 3(b), when a high-frequency current flows inside the lithium-ion battery 12 by the high-frequency generator 10A of this embodiment, the current density is different from the current density when a direct current or low-frequency current flows. As shown in FIG. 3(b), when a high-frequency current flows inside the battery, the current is concentrated at the edge of the active material layer due to the skin effect in the active material layers of the positive and negative electrodes, which have a high electrical conductivity σ. On the other hand, since the electrical conductivity σ is low in the electrolyte (separator) portion, the skin effect hardly appears (or the skin effect is alleviated), and the current flows uniformly or nearly so in the electrolyte portion. Due to such a difference in electrical conductivity σ, the current flowing at the edge of the active material layer is diffused in the surface direction at the interface between the active material layer and the electrolyte and flows uniformly. In other words, a current can flow in the surface direction at the interface between the active material layer and the electrolyte.

[0031] Battery polarization causes the current density distribution in the planar direction to become uneven, which causes the potential to vary depending on the location, resulting in lithium deposition and the like. According to the high frequency generator 10A of this embodiment, a high frequency current can be caused to flow in the planar direction, so that polarization can be mitigated and suppressed. By suppressing polarization, it is expected that the battery output will be improved and lithium deposition will be suppressed.

[0032] The above-mentioned operational effects can also be obtained in the other embodiments of the high frequency generators 10B to 10D (FIGS. 4 to 6) described below, as well as in the embodiment in which a high frequency current is superimposed on a charging current or a discharging current, described with reference to FIGS.

[0033] <Second embodiment> Next, a high frequency generator 10B according to a second embodiment will be described. FIG. 4 is a diagram showing the configuration of a high frequency generator 10B according to the second embodiment. The second embodiment differs from the first embodiment in that a high frequency signal is inserted from the outside. The current Ires in the second embodiment differs from the first embodiment in that the amplitude of the high frequency current is maintained (is not attenuated).

[0034] 4, the high frequency generator 10B includes an AC generating circuit 14B and a control device 15B. The AC generating circuit 14B includes two capacitors 27 and 29 and an AC generating device 28. The AC generating device 28 is a signal generator that applies a current of any one of a sine wave, a rectangular wave (square wave), or a triangular wave to the lithium ion battery 12.

[0035] One end of capacitor 27 is connected to the positive electrode of lithium ion battery 12, and the other end is connected to one end of AC generator 28. The other end of AC generator 28 is connected to one end of capacitor 29, and the other end of capacitor 29 is connected to the negative electrode of lithium ion battery 12.

[0036] The control device 15B controls the AC generator 28. Specifically, the control device 15B controls the form (sine wave, square wave, triangular wave, etc.) of the signal generated from the AC generator 28, the amplitude, the frequency, the length of time for which the signal is applied, the frequency with which the signal is applied, etc. The control device 15B may control the AC generator 28 so that a high-frequency current of 100 kHz or more is applied to the lithium-ion battery 12. In the second embodiment described above, the same effects as in the first embodiment can be obtained.

[0037] <Third embodiment> Next, a high frequency generator 10C according to a third embodiment will be described. Fig. 5 is a diagram showing the configuration of the high frequency generator 10C according to the third embodiment. The high frequency generator 10C includes an AC generating circuit 14C and a control device 15C. The AC generating circuit 14C includes four inductors 30, four switching elements 31, four capacitors 34, four switching elements 35, one resistor element 32, and one switching element 36.

[0038] The four inductors 30 have L (inductance) different by a power of 2, and are connected in parallel with a switching element 31 connected in series to each inductor 30. The four capacitors 34 have C (capacitance) different by a power of 2, and are connected in parallel with a switching element 35 connected in series to each capacitor 34.

[0039] One end of each inductor 30 is connected to the positive electrode of the lithium ion battery 12, and the other end is connected to one end of each capacitor 34 via a switching element 31. The other end of each capacitor 34 is connected to one end of a switching element 36 via a switching element 35. The other end of the switching element 36 is connected to the negative electrode of the lithium ion battery 12. The resistance element 32 is connected in parallel to the series circuit consisting of the capacitor 34 and the switching element 35.

[0040] The control device 15C controls four switching elements 31, four switching elements 35, and one switching element 36. Specifically, the control device 15C selectively turns on one or more of the four switching elements 31, and selectively turns on one or more of the four switching elements 35. Thereafter, the control device 15C controls the switching element 36 (FIG. 5) to be repeatedly turned on in a pulsed manner, similar to the control of the switching element 26 in the first embodiment (see FIG. 2).

[0041] According to this embodiment, the composite impedance of the inductor 30 and the capacitor 34 can be changed by the on / off pattern of the switching elements 31, 35. A damped oscillatory current Ires of various resonance frequencies can be applied to the lithium ion battery 12. The resonance frequency is determined by the composite impedance of the inductor 30 and the capacitor 34, and the current amplitude is determined by the composite impedance of the inductor 30. The control device 15C may control the switching elements 31, 35 so that a high-frequency current of 100 kHz or more is applied to the lithium ion battery 12. The control device 15C can adjust the total amount of current flow by changing the on / off cycle of the switching element 36 (resonance switch).

[0042] The third embodiment described above can also provide the same effects as those of the first embodiment. In the above-described embodiment, four inductors 30 and four capacitors 34 are connected in parallel, but the number of inductors 30 and capacitors 34 connected in parallel may be other than four.

[0043] <Fourth embodiment> Next, a high frequency generator 10D according to a fourth embodiment will be described. Fig. 6 is a diagram showing the configuration of the high frequency generator 10D according to the fourth embodiment. In the third embodiment described above, the inductance and capacitance of the AC generating circuit 14C are changed using the switching elements 31 and 35, but in the fourth embodiment, the inductance and capacitance of the AC generating circuit 14D are changed using variable capacitance capacitors (varicaps) 50 and 52 whose capacitance changes with the inter-terminal voltage.

[0044] 6, the high frequency generating device 10D includes an AC generating circuit 14D and a control device 15D. The AC generating circuit 14D includes an inductor 40, a resistive element 42, a switching element 46, two variable capacitors 50 and 52, and two power sources 60 and 62.

[0045] One end of the inductor 40 is connected to the positive electrode of the lithium ion battery 12, and the other end is connected to one end of a resistive element 42. The other end of the resistive element 42 is connected to one end of a switching element 46, and the other end of the switching element 46 is connected to the negative electrode of the lithium ion battery 12. A variable capacitor 50 is connected in parallel to the inductor 40. A variable capacitor 52 is connected in parallel to the resistive element 42. A power supply 60 is connected to the variable capacitor 50, which applies a voltage between its terminals. A power supply 62 is connected to the variable capacitor 52, which applies a voltage between its terminals.

[0046] The control device 15D controls the two power sources 60, 62 and the switching element 46. Specifically, the control device 15D adjusts the capacitance of the variable capacitor 50 by changing the terminal voltage of the variable capacitor 50 using the power source 60, and adjusts the capacitance of the variable capacitor 52 by changing the terminal voltage of the variable capacitor 52 using the power source 62. Thereafter, the control device 15D controls the switching element 46 (FIG. 6) to be repeatedly turned on in a pulsed manner, similar to the control of the switching element 26 in the first embodiment (see FIG. 2).

[0047] According to this embodiment, the combined impedance of the LC parallel circuit changes depending on the capacitance value of the variable capacitor 50 connected in parallel with the inductor 40, so that the inductance value of the AC generating circuit 14D can be changed. The control device 15D may control the capacitances of the two variable capacitors 50 and 52 so that a high-frequency current (damped oscillatory current Ires) of 100 kHz or more is applied to the lithium-ion battery 12. The AC generating circuit 14D may be used in a range of C1 where the resonant frequency of L (inductance of the inductor 40) and C1 (capacitance of the variable capacitor 50) is higher than the resonant frequency of L and C2 (capacitance of the variable capacitor 52). The fourth embodiment described above may also provide the same effects as the first embodiment.

[0048] <Combination of charge / discharge device and high frequency generator> Next, a configuration in which the high frequency generator 10 is applied to the lithium ion battery 12 connected to a charge / discharge device (power source or load) will be described. Fig. 7 is a diagram showing an example of a combination of a charge / discharge device 70 and the high frequency generator 10. The charge / discharge device 70 is an integrated representation of the power source and load of various products (electric vehicles, communication devices, information devices, etc.) that use the lithium ion battery 12. The charge / discharge device 70 functions as a power source when the lithium ion battery 12 is charged, and functions as a load when the lithium ion battery 12 is discharged.

[0049] The high frequency generator 10 is any one of the high frequency generators 10A to 10D (FIGS. 1, 4 to 6) of the first to fourth embodiments described above. In FIG. 7, the charge / discharge device 70 and the high frequency generator 10 are separated. This shows a form in which the high frequency generator 10 is added to an existing charge / discharge device 70 as a new function. The charge / discharge device 70 is connected in parallel to the lithium ion battery 12, and the high frequency generator 10 is also connected in parallel to the lithium ion battery 12. As shown in FIG. 9, the high frequency generator 10 may be incorporated in the charge / discharge device 80 to form an integrated configuration.

[0050] Here, the battery current Ib (FIG. 7) flowing through the positive and negative electrodes of the lithium ion battery 12 will be described. FIG. 8 shows an example of the battery current Ib when the lithium ion battery 12 is being charged. As shown in FIG. 8, when the lithium ion battery 12 is being charged, the battery current Ib is in a state in which a high-frequency current (AC current) generated by the high-frequency generator 10 is superimposed on a DC charging current. Although not shown, when the lithium ion battery 12 is being discharged, the battery current Ib is in a state in which a high-frequency current (AC current) generated by the high-frequency generator 10 is superimposed on a DC discharging current. Even when such a high-frequency current offset by a DC current is used, polarization of the lithium ion battery 12 can be suppressed.

[0051] Note that the high-frequency generator 10 may change various parameters of the high-frequency current (amplitude, frequency, time for applying the high-frequency current, frequency of applying the high-frequency current, etc.) according to the magnitude of the charging current or the discharging current. In this case, the control devices 15A to 15D (FIGS. 1, 4 to 6, hereinafter referred to as the control device 15) of the high-frequency generator 10 receive the values of the charging current Ibc and the discharging current Ibd (both are direct currents) from the charge-discharge device 70, and may control the AC generation circuits 14A to 14D (FIGS. 1, 4 to 6, hereinafter referred to as the AC generation circuit 14) as follows.

[0052] When the charging current Ibc of the lithium-ion battery 12 is large (Ibc = Ibc_1), the control device 15 controls the AC generation circuit 14 so that the amplitude of the high-frequency current becomes larger than when it is small (Ibc = Ibc_2, Ibc_2 < Ibc_1). Also, when the discharging current Ibd of the lithium-ion battery 12 is large (Ibd = Ibd_1), the control device 15 controls the AC generation circuit 14 so that the amplitude of the high-frequency current becomes larger than when it is small (Ibd = Ibd_2, Ibd_2 < Ibd_1).

[0053] When the charging current Ibc of the lithium-ion battery 12 is large, the control device 15 controls the AC generation circuit 14 so that the frequency of the high-frequency current increases compared to when it is small. Also, when the discharging current Ibd of the lithium-ion battery 12 is large, the control device 15 controls the AC generation circuit 14 so that the frequency of the high-frequency current increases compared to when it is small.

[0054] When the charging current Ibc of the lithium-ion battery 12 is large, the control device 15 controls the AC generation circuit 14 so that the time for applying the high-frequency current increases compared to when it is small. Also, when the discharging current Ibd of the lithium-ion battery 12 is large, the control device 15 controls the AC generation circuit 14 so that the time for applying the high-frequency current increases compared to when it is small.

[0055] The control device 15 controls the AC generating circuit 14 so that when the charging current Ibc of the lithium ion battery 12 is large, the frequency of applying a high frequency current increases compared to when the charging current Ibc is small. Also, the control device 15 controls the AC generating circuit 14 so that when the discharging current Ibd of the lithium ion battery 12 is large, the frequency of applying a high frequency current increases compared to when the discharging current Ibd is small.

[0056] It is not necessary to execute all of the above-described high frequency current controls according to the magnitude of the charging current or discharging current, and one or more of them may be executed selectively. By controlling the high frequency current according to the magnitude of the charging current or discharging current, the polarization of the lithium ion battery 12 can be effectively suppressed.

[0057] <Additional Notes> In each embodiment described above, a high-frequency current (AC current) of 100 kHz or more is applied to the lithium-ion battery 12. The high-frequency current applied to the lithium-ion battery 12 may be, for example, 100 kHz to 30 MHz. However, the upper limit of the frequency of the high-frequency current is not limited to 30 MHz, and may be a frequency lower or higher than that.

[0058] [Configuration of the present invention] Configuration 1: An AC generating circuit connected to the positive and negative electrodes of the lithium ion battery; A control device that controls the AC generating circuit so that an AC current of 100 kHz or more is applied to the lithium ion battery. A polarization suppression device for a lithium ion battery. Configuration 2: The polarization suppression device according to configuration 1, The AC generating circuit includes: The AC current is superimposed on a DC current during charging or discharging of the lithium ion battery. A polarization suppression device for a lithium ion battery. Configuration 3: The polarization suppression device according to configuration 2, The control device includes: When the charging current or discharging current of the lithium ion battery is large, the AC generating circuit is controlled so that the amplitude of the AC current is larger than when the charging current or discharging current of the lithium ion battery is small. A polarization suppression device for a lithium ion battery. Configuration 4: The polarization suppression device according to configuration 2, The control device includes: When the charging current or discharging current of the lithium ion battery is large, the AC generating circuit is controlled so that the frequency of the AC current is increased compared to when the charging current or discharging current of the lithium ion battery is small. A polarization suppression device for a lithium ion battery. Configuration 5: The polarization suppression device according to configuration 2, The control device includes: When the charging current or discharging current of the lithium ion battery is large, the AC generating circuit is controlled so that the time for applying the AC current is increased compared to when the charging current or discharging current of the lithium ion battery is small. A polarization suppression device for a lithium ion battery. Configuration 6: The polarization suppression device according to configuration 2, The control device includes: When the charging current or discharging current of the lithium ion battery is large, the AC generating circuit is controlled so as to apply the AC current more frequently than when the charging current or discharging current of the lithium ion battery is small. A polarization suppression device for a lithium ion battery. Configuration 7: A polarization suppression device according to configuration 1, 2 or 6, The AC generating circuit includes: The resonant frequency of the series circuit is determined by the series circuit, and the resonant frequency of the series circuit is determined by the series circuit. The control device controls the on / off of the switching element. A polarization suppression device for a lithium ion battery. Configuration 8: A polarization suppressing device according to any one of configurations 1 to 6, The AC generating circuit includes: A circuit that applies a sine wave, a square wave, or a triangular wave current to the lithium ion battery. A polarization suppression device for a lithium ion battery. [Explanation of symbols]

[0059] 10, 10A, 10B, 10C, 10D polarization suppression device (high frequency generator, high frequency current generator), 12 lithium ion battery, 14, 14A, 14B, 14C, 14D AC generating circuit, 15, 15A, 15B, 15C, 15D control device, 20 inductor (coil), 22 resistance element, 24 capacitor, 26 switching element, 27 capacitor, 28 AC generator, 29 capacitor, 30 inductor (coil), 31 switching element, 32 resistance element, 34 capacitor, 35, 36 switching element, 40 inductor (coil), 42 resistance element, 46 switching element, 50, 52 variable capacitance capacitor, 60, 62 power supply, 70, 80 charging / discharging device.

Claims

1. An AC generating circuit connected to the positive and negative electrodes of the lithium ion battery; A control device that controls the AC generating circuit so that an AC current of 100 kHz or more is applied to the lithium ion battery. A polarization suppression device for a lithium ion battery.

2. 2. The polarization suppression device according to claim 1, The AC generating circuit includes: The AC current is superimposed on a DC current during charging or discharging of the lithium ion battery. A polarization suppression device for a lithium ion battery.

3. The polarization suppression device according to claim 2, The control device includes: When the charging current or discharging current of the lithium ion battery is large, the AC generating circuit is controlled so that the amplitude of the AC current is larger than when the charging current or discharging current of the lithium ion battery is small. A polarization suppression device for a lithium ion battery.

4. The polarization suppression device according to claim 2, The control device includes: When the charging current or discharging current of the lithium ion battery is large, the AC generating circuit is controlled so that the frequency of the AC current is increased compared to when the charging current or discharging current of the lithium ion battery is small. A polarization suppression device for a lithium ion battery.

5. The polarization suppression device according to claim 2, The control device includes: When the charging current or discharging current of the lithium ion battery is large, the AC generating circuit is controlled so that the time for applying the AC current is increased compared to when the charging current or discharging current of the lithium ion battery is small. A polarization suppression device for a lithium ion battery.

6. The polarization suppression device according to claim 2, The control device includes: When the charging current or discharging current of the lithium ion battery is large, the AC generating circuit is controlled so as to apply the AC current more frequently than when the charging current or discharging current of the lithium ion battery is small. A polarization suppression device for a lithium ion battery.

7. A polarization suppression device according to claim 1, 2 or 6, The AC generating circuit includes: The resonant frequency of the series circuit is determined by the series circuit, and the resonant frequency of the series circuit is determined by the series circuit. The control device controls the on / off of the switching element. A polarization suppression device for a lithium ion battery.

8. The polarization suppression device according to any one of claims 1 to 6, The AC generating circuit includes: A circuit that applies a sine wave, a square wave, or a triangular wave current to the lithium ion battery. A polarization suppression device for a lithium ion battery.

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