KR20230039583A - Electrochemical Impedance Spectroscopy System - Google Patents

Abstract

The present invention discloses an electrochemical impedance spectroscopy system for measuring the impedance of a battery. For example, disclosed is an electrochemical impedance spectroscopy system, which is coupled to a battery module including at least one battery cell to apply charging and discharging current, comprising: a charging and discharging part for supplying charging and discharging current; a sensing part branching from a wire for connecting the charging and discharging part and the battery module to measure the voltage of the battery module; and a data collection part for collecting the voltage of the battery module from the sensing part, wherein the sensing part includes a ripple removal part for receiving the voltage of the battery module and removing ripples.

Description

Electrochemical Impedance Spectroscopy System}

The present invention relates to an electrochemical impedance spectroscopy system for measuring the impedance of a battery.

An Electrochemical Impedance Spectroscopy System (EIS) has been used to test rechargeable batteries such as lithium ion batteries.

EIS is well suited to observing the dynamic responses of electrodes and batteries. In EIS, the impedance of a battery over a range of frequencies is measured. The battery's energy storage and dissipation characteristics can be revealed by examining the resulting frequency response curve. Impedance parameters such as ohmic resistance and charge transfer resistance can be evaluated, for example, from a Nyquist plot of the battery's frequency response.

Other parameters that can be measured with EIS can be related to the bilayer effect, which is the formation of two layers of opposite polarity at the interface between electrode and electrolyte. Also, as other parameters measurable by EIS, diffusion and reaction parameters are known which change during battery charging and discharging and also depend on battery age, state of health and temperature.

The present invention provides an electrochemical impedance spectroscopy system for measuring the impedance of a battery.

An electrochemical impedance spectroscopy system according to the present invention is coupled to a battery module including at least one battery cell and applies a charging/discharging current, comprising: a charging/discharging unit supplying a charging/discharging current; a sensing unit branched off from a wire connecting the charging/discharging unit and the battery module to measure a voltage of the battery module; The sensor may include a data collection unit that collects the voltage of the battery module from the sensing unit, and the sensing unit may include a ripple removal unit that receives the voltage of the battery module and removes the ripple.

Here, the ripple remover may remove the ripple from the voltage of the battery module by selecting only the direct current component of the voltage of the battery module.

Also, the ripple removal unit may include a low pass filter.

In addition, the sensing unit may measure a final voltage by applying the voltage passing through the ripple removal unit as an offset from the voltage of the battery module.

In addition, the data collection unit may receive a trigger signal from the charging/discharging unit and perform synchronization with the final voltage.

Also, the charger/discharger may include a high voltage charger generating a relatively high voltage and a fast charger/discharger connected in series to the high voltage charger and generating a relatively low voltage.

Also, the high voltage charger may generate a DC voltage, and the high-speed charger/discharger may generate an AC voltage.

In addition, a high voltage discharger connected in parallel to the high voltage charger may be further included.

Also, the high voltage discharger may be composed of an electronic load.

In addition, a current flowing through the high voltage discharger may not be 0 [A] while charging and discharging current is applied to the battery module.

In addition, a correction current may be set for the high voltage discharger, and the correction current may be constantly applied to the high voltage discharger while charging and discharging current is applied to the battery module.

In addition, the impedance of the battery may be measured by simultaneously applying charge/discharge current to the battery module and a battery pack formed by electrically connecting a plurality of battery modules to each other.

The electrochemical impedance spectroscopy system according to the present invention can measure an accurate voltage waveform without a separate offset power supply or program, and can provide an EIS generator capable of high voltage.

1 is a schematic configuration diagram of an electrochemical impedance spectroscopy system according to an embodiment of the present invention.
2 is a configuration diagram illustrating a connection relationship between a battery module in a battery pack and a charging/discharging unit in an electrochemical impedance spectroscopy system according to an embodiment of the present invention.
3 is an exemplary circuit diagram showing the configuration of a ripple removal unit in an electrochemical impedance spectroscopy system according to an embodiment of the present invention.
4 is a configuration diagram illustrating a charging operation of a charging/discharging unit in an electrochemical impedance spectroscopy system according to an embodiment of the present invention.
5 is a configuration diagram illustrating a discharge operation of a charging/discharging unit in an electrochemical impedance spectroscopy system according to an embodiment of the present invention.
6 is a graph showing voltage and current in a battery module and a charging/discharging unit in an electrochemical impedance spectroscopy system according to an embodiment of the present invention.
7A and 7B are Nyquist charts for comparing effects of an electrochemical impedance spectroscopy system according to an embodiment of the present invention.
8 is an exemplary waveform showing voltage and current in a battery module and a charging/discharging unit in an electrochemical impedance spectroscopy system according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art, and the following examples may be modified in many different forms, and the scope of the present invention is as follows It is not limited to the examples. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the spirit of the invention to those skilled in the art.

In addition, in the following drawings, the thickness or size of each layer is exaggerated for convenience and clarity of explanation, and the same reference numerals refer to the same elements in the drawings. As used herein, the term "and/or" includes any one and all combinations of one or more of the listed items. In addition, the meaning of "connected" in the present specification means not only when member A and member B are directly connected, but also when member A and member B are indirectly connected by interposing member C between member A and member B. do.

Terms used in this specification are used to describe specific embodiments and are not intended to limit the present invention. As used herein, the singular form may include the plural form unless the context clearly indicates otherwise. Also, when used herein, "comprise" and/or "comprising" specifies the presence of the recited shapes, numbers, steps, operations, elements, elements, and/or groups thereof. and does not exclude the presence or addition of one or more other shapes, numbers, operations, elements, elements and/or groups.

In this specification, terms such as first and second are used to describe various members, components, regions, layers and/or portions, but these members, components, regions, layers and/or portions are limited by these terms. It is self-evident that These terms are only used to distinguish one element, component, region, layer or section from another region, layer or section. Thus, a first member, component, region, layer or section described in detail below may refer to a second member, component, region, layer or section without departing from the teachings of the present invention.

Space-related terms such as “beneath,” “below,” “lower,” “above,” and “upper” are associated with an element or feature shown in a drawing. Used for easy understanding of other elements or features. Terminology related to this space is for easy understanding of the present invention according to various process conditions or use conditions of the present invention, and is not intended to limit the present invention. For example, if an element or feature in a drawing is flipped over, an element described as "lower" or "below" becomes "above" or "above." Accordingly, "below" is a concept encompassing "upper" or "below".

Hereinafter, the configuration of an electrochemical impedance spectroscopy system according to an embodiment of the present invention will be described.

1 is a schematic configuration diagram of an electrochemical impedance spectroscopy system according to an embodiment of the present invention. 2 is a configuration diagram illustrating a connection relationship between a battery module in a battery pack and a charging/discharging unit in an electrochemical impedance spectroscopy system according to an embodiment of the present invention. 3 is an exemplary circuit diagram showing the configuration of a ripple removal unit in an electrochemical impedance spectroscopy system according to an embodiment of the present invention.

First, referring to FIG. 1 , an electrochemical impedance spectroscopy system 10 according to an embodiment of the present invention includes a battery pack 100, a charging/discharging unit 200, a sensing unit 300, and a data collecting unit 400. can do.

Here, the battery pack 100 may include a plurality of battery modules 110_1 to 110_n therein. In addition, each of the battery modules 110_1 to 110_n may be connected in series with each other, but may be configured in parallel or in series and parallel according to design by those skilled in the art. Such a battery pack 100 may be referred to as a battery rack according to product characteristics.

In addition, the battery pack 100 may include a charge/discharge terminal 120 and a cell monitoring unit 130 configured in each of the battery modules 110_1 to 110_n. For convenience of description, description will be made focusing on the first components of the battery modules 110_1 to 110_n.

The battery module 110_1 may include a plurality of battery cells (not shown) arranged therein. In general, each battery cell is connected in series with each other, and it is also possible to be configured in parallel or series-parallel according to the design of those skilled in the art. The battery cell may be configured as a secondary battery capable of charging and discharging like a typical lithium ion battery.

In addition, the charge/discharge terminal 120 may be provided in each of the battery modules 110_1 to apply a charge/discharge current to the battery module 120 . The charge/discharge terminal 120 may include, for example, first and second external terminals 121 and 122 having different polarities and first and second internal terminals 123 and 124 having different polarities. Here, the first external terminal 121 and the first internal terminal 123 may have the same polarity, and the second external terminal 122 and the second internal terminal 124 may also have the same polarity. In addition, a fuse 125 is provided between the first external terminal 121 and the first internal terminal 123 to block current in case of overcharging or overdischarging. However, the fuse 125 may also be provided between the second external terminal 122 and the second internal terminal 124 .

Meanwhile, the cell monitoring unit 130 is provided inside the battery module 110_1 to sense the voltage and current of each cell in the module. In addition, when an abnormal voltage or current is detected in some of the cells, the charging/discharging current supplied to the battery module 110_1 may be cut off through communication with the charging/discharging unit 200 .

The charging/discharging unit 200 may be connected to the battery pack 100 to perform charging/discharging operations on each of the battery modules 110_1 to 110_n. Here, the charge/discharge unit 200 converts a voltage or current waveform in the form of a high-speed charge/discharge sine in the range of 0.1 [Hz] to 1 [kHz] to the battery pack 100 for optical chemical impedance spectral characteristic (EIS) measurement. , and the voltage or current of the entire battery pack 100 including each of the battery modules 110_1 to 110_n_ and a plurality of battery modules 110_1 to 110_n may be measured and analyzed.

In order to simultaneously measure the series-connected battery modules 110_1 to 110_n within the battery pack 100, the charging/discharging unit 200 supplies a current waveform and measures a voltage in response to the module 110_1 as well as the battery pack 100. to 110_n) can be measured simultaneously at one time. Also, for this purpose, the charging/discharging unit 200 may transmit a trigger signal Trig to the data collecting unit 400 for each frequency.

The charging/discharging unit 200 may be connected to the battery pack 100 through wires. For example, the positive terminal of the charging/discharging unit 200 is connected to the first external terminal 121 of the first battery module 110_1, and the charging/discharging unit 200 is connected to the second external terminal 125 of the last battery module 110_n. Negative terminals may be connected through wires 201 and 202. In addition, each battery module 110_1 to 110_n is connected to each other through a separate wire 203, so that the entirety of battery modules 110_1 to 110_n is a charge/discharge unit. A charge/discharge current of (200) is applied.

Meanwhile, referring to FIG. 2 together, the charging/discharging unit 200 may include a high voltage charging unit 210, a high voltage discharging unit 220, a high-speed charging/discharging unit 230 and .

Here, the high voltage charger 210 may be used for the purpose of applying a basic high voltage required for charging the battery pack 100 . Since the battery pack 100 includes a plurality of battery modules 110_1 to 110_n and each module 110_1 to 110_n includes a plurality of battery cells, the charging voltage of the battery pack 100 is basically a high voltage. , for example, may be 51 [V]. In addition, the high voltage charging unit 210 may maintain a constant voltage, for example, a voltage of 40 [V], and apply the voltage to the battery pack 100 .

The high voltage discharge unit 220 may be connected in parallel to the high voltage charger 210 . The high voltage discharge unit 220 may be composed of an electrical load. The electronic load is required for precise power supply, and in particular, it is possible to set the load in a wide range through programming, and it can perform a function of maintaining a constant amount of current flowing despite a change in applied voltage. According to this, when the current applied from the high voltage charging unit 210 is applied to the high voltage discharging unit 220, the amount of current can be kept constant, so that the amount of current finally delivered to the battery pack 100 can be maintained.

The high-speed charge/discharge unit 230 may be connected in series to parallel branches of the high voltage charger 210 and the high voltage discharge unit 220 . The high-speed charge/discharge unit 230 may be configured as an EIS generator. The EIS generator has insulation characteristics that can sufficiently withstand a high voltage and generates a relatively low voltage compared to the high voltage charging unit 210 or the high voltage discharging unit 220, but can perform current control at high speed. Therefore, the high voltage charging unit 210 and the high voltage discharging unit 220 need only serve to generate a high voltage without a high-speed control function, and the low voltage can be controlled at high speed through the high-speed charging and discharging unit 230 connected in series. The voltage applied to the pack 100 can be smoothly controlled.

The sensing unit 300 may include a ripple removal unit 310 and a sensor 320 respectively coupled to each battery module 110_1 to 110_n of the battery pack 100 . In addition, the sensing unit 300 may further include a ripple removal unit 330 and a sensor 340 connected to wires 201 and 202 connected to the battery pack 100 in the charging/discharging unit 200 . The sensing unit 300 may perform a function of detecting a voltage waveform of the battery pack 100 or each of the battery modules 110_1 to 110_n and transmitting the corresponding voltage waveform to the data collection unit 400 .

In particular, the sensing unit 300 receives voltage and current from the battery pack 100 or the battery modules 110_1 to 110_n, and extracts only the high voltage component from which the ripple is removed through the ripple removal unit 310. .

Referring to FIG. 3 together, the ripple remover 310 may be illustratively connected to the first and second external terminals 121 and 122 of the first battery module 110_1 . The ripple removal unit 310 may include, for example, a low pass filter. For example, as shown, the first external terminal 121 is connected to a diode D1 and a first resistor R1 connected in series, and then a capacitor C1 and a second resistor R2 forming a parallel branch. ), so that the ripple component of the voltage at both ends of the first external terminal 121 and the second external terminal 122 can be removed.

In addition, the sensing unit 300 applies the voltage of the battery pack 100 or the battery modules 110_1 to 110_n to one terminal of the sensor 320 and applies a high voltage component from which the ripple is removed to the other terminal, thereby providing an offset It can be offset by using it as an offset. Therefore, the sensor 320 can detect and extract only a sine-shaped voltage waveform having a size of several tens [mV] corresponding to the ripple.

Through this configuration of the sensing unit 300, among the voltages of the battery pack 100 or the battery modules 110_1 to 110_n having tens to hundreds [V], it is possible to accurately measure only voltage waveforms of several tens [mV]. possible. In addition, since the sensing unit 300 does not require an offset using a separate high-precision high voltage generator, manufacturing cost can be reduced, and the amount of calculation can be reduced because a separate offset removal function is not required in the analysis software. .

The data collection unit 400 may be connected to the sensor 320 of the sensing unit 300 . The data collector 400 may receive voltage and current waveform data of the battery pack 100 and each battery module 110_1 to 110_n from each sensor 320 and analyze them. In particular, the data collection unit 400 synchronizes the voltage and current waveforms of the sensor 320 with respect to the charging/discharging voltage and current of the charging/discharging unit 200 through the trigger signal previously received from the charging/discharging unit 200, thereby accurately measuring impedance. can be analyzed.

Hereinafter, the operation of the electrochemical impedance spectroscopy system according to an embodiment of the present invention will be described in detail.

4 is a configuration diagram illustrating a charging operation of a charging/discharging unit in an electrochemical impedance spectroscopy system according to an embodiment of the present invention. 5 is a configuration diagram illustrating a discharge operation of a charging/discharging unit in an electrochemical impedance spectroscopy system according to an embodiment of the present invention. 6 is a graph showing voltage and current in a battery module and a charging/discharging unit in an electrochemical impedance spectroscopy system according to an embodiment of the present invention. 7 is an exemplary waveform showing voltage and current in a battery module and a charging/discharging unit in an electrochemical impedance spectroscopy system according to an embodiment of the present invention.

First, as shown in FIG. 4 , when charging the battery pack 100 through the charging/discharging unit 200, the current generated by the high voltage charger 210 and the high-speed charger/discharger 230 is the battery pack ( 100) can be applied. Specifically, the voltage (V ₁ ) generated by the high voltage charger 210 generates a charging voltage (V _bat ) in series with the voltage (V ₂ ) generated by the high-speed charger/discharger 230, and the battery pack 100 may be authorized.

In addition, in the current (I ₁ ) of the high voltage charger 210, a portion of the current (I _Load ) is branched and flows in the high voltage discharger 220, and the remaining current is combined with the current (I ₂ ) of the high-speed charger/discharger 230, so that it is also a battery. It may be applied as a charging current (I _bat ) to the pack 100 .

At this time, as described above, the voltage (V ₁ ) and current (I ₁ ) generated by the high voltage charger 210 are compared to the voltage (V ₂ ) and current (I ₂ ) generated by the high-speed charger/discharger 230 . Since it is a direct current component having a large value, it may occupy a relatively large proportion in the charging voltage (V _bat ) and the charging current (I _bat ). In addition, the high-speed charger and discharger 230 generates relatively low voltage (V ₂ ) and current (I ₂ ), but generates a high-speed sine waveform, thereby generating the final charging voltage (V _bat ) and charging of the AC waveform. A current (I _bat ) can be generated.

On the other hand, as shown in FIG. 5 , when discharging the battery pack 100 through the charging/discharging unit 200, the high voltage discharger 220 and the high-speed charger/discharger 230 are used in the opposite direction to that of charging. As a result, a discharge current (I _bat ) may be applied from the battery pack 100 to the high voltage discharger 220 . Specifically, the voltage (V _bat ) of the battery pack 100 may be divided into the voltage (V _Load ) of the high voltage discharger 220 and the voltage (V ₂ ) of the high-speed charger/discharger 230 , respectively. In addition, through this operation, the high voltage discharger 220 and the high-speed charger/discharger 230 may operate as a load of the discharge operation.

In addition, the current (I ₁ ) of the high voltage charger 210 flows to the high voltage discharger 220, so that the current (I _Load ) of the high voltage discharger 220 is the current (I ₁ ) of the high-speed charger/discharger 230 and the high voltage charger 210 ) of the current (I ₂ ) may have a combined form.

Referring to FIG. 6 , voltages and currents used in charge/discharge operations in FIGS. 4 and 5 are shown as graphs. In the graph of FIG. 6, the horizontal axis represents voltage (V), and the vertical axis represents current (I). In addition, in the first quadrant, both voltage and current have a positive sign (+) for charging operation, and in the fourth quadrant, voltage has a positive sign (+) and current has a negative sign (-) and discharge (or as a load) Also referred to as a sink) operation.

And, for the voltage (V ₁ ) and current (I ₁ ) in the high-voltage charger ₂₁₀ , a positive current (I 1 ) with more corrected current (I _delta ) added compared to the current (I _source ) generated by the charger itself is set, and for the voltage (V ₂ ) and current (I ₂ ) in the high voltage discharger 220, a positive current in which the correction current (I _delta ) is further added compared to the current consumption (I _Load ) of the discharger itself (I ₂ ) is set. As a result of these settings, the current of the high voltage discharger 220 does not always become 0 [A], and at least as much as the corrected current I _delta flows. As a result of these settings, it is possible to fundamentally prevent the occurrence of noise components generated when the current is switched to 0 [A] in the high voltage discharger 220 . Therefore, it has an advantage of reducing generation of ripple including noise in components of the final voltage and current generated by the charging/discharging unit 200 .

Hereinafter, effects of the electrochemical impedance spectroscopy system according to an embodiment of the present invention will be described in detail.

7A and 7B are Nyquist charts for comparing effects of an electrochemical impedance spectroscopy system according to an embodiment of the present invention. 8 is an exemplary waveform showing voltage and current in a battery module and a charging/discharging unit in an electrochemical impedance spectroscopy system according to an embodiment of the present invention.

Referring to FIG. 7A , impedance measurement results using a conventional electrochemical impedance spectroscopy system are shown as a Nyquist diagram. In addition, referring to FIG. 7B , impedance measurement results using the electrochemical impedance spectroscopy system according to an embodiment of the present invention are also shown as a Nyquist diagram. In addition, when using the electrochemical impedance spectroscopy system according to the present invention, it can be confirmed that precise results can be obtained because there is no irregular noise in the measurement result of impedance compared to the use of a conventional system.

8, the voltage (or charge/discharge voltage, V _bat ) of the battery module 110_1, the voltage after DC filtering, the battery current (or charge/discharge current, I _bat ), and the voltage of the high voltage discharger 220 The voltage (V _Load ) and the voltage (V ₂ ) of the high-speed charger/discharger 230 are shown together. As shown, it can be seen that the waveforms of each voltage and current have the same phase.

What has been described above is only one embodiment for implementing the electrochemical impedance spectroscopy system according to the present invention, and the present invention is not limited to the above embodiment, and the subject matter of the present invention as claimed in the following claims Anyone with ordinary knowledge in the field to which the present invention pertains without departing from the technical spirit of the present invention to the extent that various changes can be made.

10; Electrochemical warfare impedance spectroscopy system 100; battery pack
110_1 to 110_n; battery module 120; charge/discharge terminal
130; cell monitoring unit 200; charging and discharging
210; high voltage charger 220; high voltage discharge part
230; high-speed charging and discharging unit 300; sensing unit
310, 330; Ripple removal units 320, 340; sensor
400; data collection department

Claims (12)

In the electrochemical impedance spectroscopy system coupled to a battery module including at least one battery cell and applying a charge/discharge current,
a charge/discharge unit supplying charge/discharge current;
a sensing unit branched off from a wire connecting the charging/discharging unit and the battery module to measure a voltage of the battery module;
And a data collection unit for collecting the voltage of the battery module from the sensing unit,
The sensing unit includes a ripple removal unit configured to receive a voltage of the battery module and remove ripple. According to claim 1,
The system of claim 1 , wherein the ripple remover removes ripple from the voltage of the battery module by selecting only a direct current component of the voltage of the battery module. According to claim 2,
The ripple removal unit is a system composed of a low pass filter. According to claim 1,
The system for measuring the final voltage through the sensing unit by applying the voltage passing through the ripple removal unit as an offset from the voltage of the battery module. According to claim 1,
The data collection unit receives a trigger signal from the charging and discharging unit and performs synchronization with the final voltage. According to claim 1,
The system of claim 1 , wherein the charger/discharger includes a high voltage charger generating a relatively high voltage and a fast charger/discharger connected in series to the high voltage charger and generating a relatively low voltage. According to claim 6,
The system of claim 1 , wherein the high voltage charger generates a direct current voltage, and the high-speed charger and discharger generates an alternating current voltage. According to claim 6,
The system further includes a high voltage discharger connected in parallel to the high voltage charger. According to claim 8,
The system of claim 1, wherein the high voltage discharger is composed of an electronic load. According to claim 8,
A system in which a current flowing through the high voltage discharger does not become 0 [A] while charging and discharging current is applied to the battery module. According to claim 10,
A system in which a correction current is set for the high voltage discharger, and the correction current is always applied to the high voltage discharger while charging and discharging current is applied to the battery module. According to claim 1,
A system for measuring impedance of a battery by simultaneously applying charge/discharge current to the battery module and a battery pack formed by electrically connecting the plurality of battery modules to each other.

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