KR20220146995A - Method for charging battery and apparatus for charging battery - Google Patents

Abstract

A method for charging a battery and an apparatus for charging a battery are disclosed. According to one aspect of the present invention, there is provided a method of measuring an impedance for each frequency by sequentially applying alternating currents of different frequencies to a battery; setting a frequency of the alternating current at which chemical diffusion starts in the battery from the measured impedance for each frequency as a diffusion resistance frequency; and charging the battery by applying a pulse charging current to the battery at a charging frequency higher than the diffusion resistance frequency.

Description

A method for charging a battery and an apparatus for charging a battery {Method for charging battery and apparatus for charging battery}

The present invention relates to a method for charging a battery and an apparatus for charging a battery. More particularly, it relates to a battery charging method and a battery charging apparatus capable of rapidly charging a battery by charging the battery with a high current in the form of a pulse having a frequency range capable of preventing the battery from aging.

As the problem of global warming has become very serious, interest in eco-friendly energy is increasing more than ever. In the process of utilizing such eco-friendly energy, one of the most important factors is an energy storage device that stores the generated energy. As is well known, lithium-ion-based batteries are now widely used. The development and spread of electric vehicles, which are progressing along with this eco-friendly energy trend, is contributing greatly to the more widespread use of secondary batteries such as lithium-ion batteries. However, in the case of electric vehicles, there are many cases in which the vehicle can be conveniently used only when charging is performed quickly, so the demand for such fast charging is very high.

In general, when the battery is charged over the rated current (usually 1C-Rate or higher), the charge/discharge performance of the battery deteriorates, the battery ages rapidly, and the internal resistance increases quantity will decrease. Due to this rapid aging phenomenon, fast charging of batteries is relatively strictly limited except in most cases. A method for improving the charging speed has been suggested through many studies on the aging phenomenon of the battery, but the theoretical background is insufficient, so an effective improvement of an additional super-fast charging algorithm is required.

In order to proceed with fast charging while minimizing the aging of the battery, it is necessary to carefully consider the phenomena occurring inside the battery. When a large amount of current is supplied in order to increase the charging speed, that is, when the C-Rate is increased, a lithium plating phenomenon increases due to an excessive concentration of lithium ions on the negative electrode side, thereby increasing charging inefficiency. In addition, the high current applied to increase the charging rate causes the Solid Electrolyte Interphase (SEI) at the negative electrode interface to overgrow, resulting in an increase in the temperature of the battery, which in turn accelerates the aging of the battery, including deterioration of the battery. In other words, simply increasing the charging current enables fast charging, but there is a risk of severely damaging the life of the battery.

Republic of Korea Patent Publication No. 10-2012-0010029 (published on February 2, 2012)

An object of the present invention is to provide a battery charging method and a battery charging apparatus capable of rapidly charging a battery by charging the battery with a high current in the form of a pulse having a frequency range capable of preventing the battery from aging.

According to one aspect of the present invention, there is provided a method of measuring an impedance for each frequency by sequentially applying alternating currents of different frequencies to a battery; setting a frequency of the alternating current at which chemical diffusion starts in the battery from the measured impedance for each frequency as a diffusion resistance frequency; and charging the battery by applying a pulse charging current to the battery at a charging frequency higher than the diffusion resistance frequency.

The battery may be a lithium ion battery.

The pulse charging current may be 1C (C-rate) or more.

The pulse of the pulsed charging current may be a rectangular pulse waveform that intermittently interrupts the charging current.

The battery charging method may further include performing constant current charging by applying a constant current to the battery before charging the battery by applying the pulse charging current to the battery.

The charging of the battery may include lowering or increasing the pulse charging current in stages so that the charging voltage of the battery cell is maintained below a preset maximum charging voltage of the battery cell.

In the step of measuring the impedance for each frequency, an alternating current is sequentially applied from a high frequency to a low frequency to the battery to obtain a resistance R, a capacitance C, and an inductance L of the impedance for each frequency. It may include a step of calculating.

The step of measuring the impedance for each frequency may further include the step of creating a Nyquist Plot according to the resistance R, the capacitance C, and the inductance L of the impedance for each frequency can

In the setting of the diffusion resistance frequency of the alternating current, the frequency of the alternating current at which chemical diffusion starts in the Nyquist diagram may be set as the diffusion resistance frequency.

The starting point of the chemical diffusion may be a starting point of a Warburg impedance in the Nyquist diagram.

According to another aspect of the present invention, a charging device body having a charging connector electrically connected to a terminal of a battery; An AC power supply for applying alternating currents of different frequencies to the battery, an impedance measuring unit for measuring impedances for each frequency according to the application of the alternating current, and from the measured impedances for each frequency, chemical diffusion in the battery starts a battery state information measuring unit including a charging frequency setting unit for setting the frequency of the alternating current to a diffusion resistance frequency; and a pulse charging unit provided in the charging device body and charging the battery by applying a pulse charging current to the battery at a charging frequency higher than the diffusion resistance frequency.

The battery may be a lithium ion battery.

The pulse charging current may be 1C (C-rate) or more.

The pulse of the pulse charging current may be a rectangular pulse waveform that intermittently interrupts the alternating current.

The pulse charging power supply unit may apply a constant current to the battery before applying the pulse charging current to the battery to perform constant current charging.

The pulse charging power supply unit may charge the battery cell while lowering or increasing the pulse charging current in stages so that the charging voltage of the battery cell is maintained below a preset maximum charging voltage of the battery cell.

The impedance measuring unit may calculate a resistance R, a capacitance C, and an inductance L of the impedance for each frequency by sequentially applying an alternating current from a high frequency to a low frequency to the battery.

The impedance measuring unit creates a Nyquist Plot according to the resistance R, the capacitance C, and the inductance L of the impedance for each frequency, and the charging frequency setting unit, the Nyquist The frequency of the alternating current at which chemical diffusion starts in the streaky diagram may be set as the diffusion resistance frequency.

The starting point of the chemical diffusion may be a starting point of a Warburg impedance in the Nyquist diagram.

According to an embodiment of the present invention, the battery can be charged at a high speed by charging the battery with a high current in the form of a pulse having a frequency range capable of preventing the battery from aging.

1 is a flowchart of a method for charging a battery according to an embodiment of the present invention;
FIG. 2 is a view for explaining a change in state inside a battery according to application of a charging current; FIG.
3 is a Nyquist plot of the internal impedance of a typical battery;
4 is a Nyquist plot shown through EIS analysis for a battery;
5 is a diagram illustrating a form of applying a pulse charging current in a method for charging a battery according to an embodiment of the present invention.
6 is a modified example of a form of applying a pulse charging current of a method for charging a battery according to an embodiment of the present invention.
7 is a block diagram of a battery charging apparatus according to another embodiment of the present invention.
8 is a block diagram of an electric vehicle charging system having a battery charging device according to another embodiment of the present invention.

Since the present invention can apply various transformations and can have various embodiments, specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. In describing the present invention, if it is determined that a detailed description of a related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

Terms such as first, second, etc. may be used to describe various elements, but the elements should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as "comprises" or "have" are intended to designate that the features, numbers, steps, operations, components, parts, or combinations thereof described in the specification exist, but one or more other features It is to be understood that this does not preclude the possibility of the presence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Hereinafter, an electric vehicle charging system having a battery management system according to the present invention will be described in detail with reference to the accompanying drawings. and a redundant description thereof will be omitted.

1 is a flowchart of a battery charging method according to an embodiment of the present invention. And, FIG. 2 is a view for explaining a state change in the battery according to high current charging. 3 is a Nyquist plot of the internal impedance of a typical battery, and FIG. 4 is a Nyquist plot shown through EIS analysis for several batteries. 5 is a diagram illustrating a pulse charging current application form of a battery charging method according to an embodiment of the present invention, and FIG. 6 is a modification of a pulse charging current application form of a battery charging method according to an embodiment of the present invention. Yes.

1 to 5 , a battery 10 , a negative electrode material 12 , a separator 14 , a positive electrode material 16 , a cation 18 , and an SEI 20 are illustrated.

The battery charging method according to the present embodiment includes the steps of sequentially applying alternating currents of different frequencies to the battery 10 to measure impedance for each frequency; calculating a frequency of an alternating current at which chemical diffusion starts in the battery 10 from the measured impedance for each frequency as a diffusion resistance frequency; and charging the battery 10 by applying a pulse charging current to the battery 10 at a charging frequency higher than the diffusion resistance frequency.

The battery 10 capable of charging and discharging, that is, the secondary battery, converts chemical energy into electrical energy and discharges (=discharges) it, and supplies electrical energy in a conversely discharged state (= When charged, it refers to a battery that can store it back in the form of chemical energy, that is, a battery that can alternately repeat charging and discharging. The battery 10 according to the present embodiment includes a secondary battery capable of charging electrons, such as a lead acid battery, a nickel cadmium battery, a lithium polymer battery, a lithium ion battery, a nickel hydrogen battery, and the like.

Among them, a lithium ion battery has no memory phenomenon and has good battery output, and thus a lot of research and development has been made recently. Hereinafter, a battery charging method will be described in detail with a focus on the lithium ion battery.

As a charging method of a lithium ion battery, a constant current/constant voltage (CC/CV, Constant Current/Constant Voltage) charging method has been commercialized, but in this embodiment, the current capable of fast charging while minimizing the aging of the battery 10 is pulsed. We would like to propose a pulse charging method that is applied to

FIG. 2 is a view for explaining a state change in the battery 10 according to the application of charging current.

The battery 10 is composed of a positive electrode material 16, a negative electrode material 12, a separator 14, an electrolyte, etc., while supplying positive ions from the positive electrode material 16 and receiving or discharging positive ions from the negative electrode material 12 Electricity charging and discharging takes place. In the case of a lithium ion battery, lithium oxide is used as the positive electrode material 16 and graphite is mainly used as the negative electrode material 12. Lithium ions, which are cations, pass through the separator 14 to pass through the negative electrode material 12 and the positive electrode material 16. Charging and discharging of electricity occurs as it goes back and forth.

FIG. 2 is a view for explaining a change in state inside the battery 10 according to the application of charging current. FIG. 2 (a) shows a state in which a high current charging current is applied, FIG. 2 (b) and (c) show a state in which an appropriate current is applied and released.

When a high current (for example, 1 C-rate or more) charging current is applied to the battery 10 in order to increase the charging speed of the battery 10 , as shown in (a) of FIG. 2 , the negative electrode The internal resistance increases as the cation 18 and the electrolyte-changed residue thickly cover the solid electrolyte interface (Solid Electrolyte Interphase, hereinafter referred to as 'SEI (20)') at the interface of the ashes 12, and in this situation, the internal resistance increases. When a high current is continuously applied, the SEI 20 is further grown as the temperature of the thick layer rises, and as a result, the internal resistance is increased more rapidly and the aging of the battery 10 is accelerated.

On the other hand, as shown in (b) of FIG. 2, when an appropriate level of charging current (for example, 1 C-rate or less) is applied to the battery 10, the positive ions 18 that accumulate while covering the SEI 20 are ) is properly charged as it permeates into the negative electrode material 12 of the battery 10 while passing through the SEI 20 , while the positive ions 18 passing through the SEI 20 balance the negative electrode material 12 inside is charged with and does not accelerate the growth of the SEI 20 . However, in this case, the charging speed is a little slow. In addition, when the supply of charging current is cut off in this state, as shown in (c) of FIG. 20) It is charged while slowly permeating between the cations 18 to stably move into the negative electrode material 12 .

2(b) and 2(c) above show the charging state of the positive ions 18 inside the battery 10 according to the application and release of the charging current. According to FIG. 2(c), the charging current is It can be seen that the positive ions 18 are being charged between the negative electrode materials 12 even in the disconnected state. That is, this charging process means that high-speed charging of the battery 10 is possible by charging in the form of a pulse that intermittently intermits the application of current.

However, it is important to determine the intermittent time and frequency of the application and release of the charging current, and the present invention intends to propose a method for determining the frequency during pulse charging.

Hereinafter, a method for charging a battery according to the present embodiment will be described in detail.

First, alternating currents of different frequencies are sequentially applied to the battery 10 to measure the impedance for each frequency (S100).

The internal resistance, that is, the impedance of the battery 10 is measured, and the degree of aging of the battery 10 is measured accordingly. AC current is sequentially applied to the battery 10 from a high frequency to a low frequency to determine the response according to each frequency. By measuring the amplitude and phase change, it is possible to measure the impedance for each frequency of the applied alternating current. Impedance can be measured using an impedance measuring device (LCR meter).

In the impedance measurement process, resistance R, capacitance C, and inductance L of the impedance for each frequency are calculated. Resistance, capacitance, and inductance of impedance for each frequency are displayed on a complex impedance plane called a Nyquist plot, which will be described later, and can be expressed as a graph by connecting the indicated points.

This process may be performed according to electrochemical impedance spectroscopy (hereinafter referred to as 'EIS').

Next, the frequency of the alternating current at which chemical diffusion starts in the battery 10 is set as the diffusion resistance frequency from the measured impedance for each frequency (S200).

If an analysis of the measured impedance for each frequency is performed, the electrochemical reaction occurring between the two electrodes and the electrolyte present inside the battery 10 can be modeled and analyzed in the form of an equivalent electric circuit, from the Nyquist diagram This can be interpreted.

The Nyquist Plot is a figure showing the complex quantity of impedance as a _real part on the horizontal axis and an imaginary part on the vertical axis. (Z _imag ) represents capacitance and inductance, and the relationship between Z _real , Z _imag is plotted as a function of frequency.

3 shows a Nyquist diagram of impedance for each frequency obtained through EIS analysis for a typical secondary battery. Referring to FIG. 3 , a typical secondary battery has an external electrolyte resistance R _bulk , a film resistance R _film corresponding to charge transfer in SEI generated on the inner electrode particle surface, and a charge representing a cationic redox reaction at the electrode material interface. It can be configured as an equivalent circuit with four resistance components: transfer resistance R _ct , and chemical diffusion resistance R _diff due to intercalation into the grain crystal structure.

R _bulk , R _film , and R _ct mainly represent the resistance component to the movement of ions through the electrolyte, and R _diff after that is related to the diffusion rate of ions, and the -Zimag value increases with an approximate 45° slope in this part. This is due to the Warburg impedance.

Since the diffusion rate of ions is relatively slow, the effect is insignificant at high frequency and the characteristic appears at low frequency. It is defined as a frequency, and it is intended to prevent aging of the battery 10 due to diffusion of ions in the electrolyte during the charging process by applying a pulse charging current at a charging frequency higher than the diffusion storage frequency during pulse charging.

4 shows a Nyquist plot by performing EIS analysis on the actual battery 10. The frequency of the applied AC voltage at the starting point of chemical diffusion shown in FIG. 4 can be set as the diffusion resistance frequency. have. The chemical diffusion start point can be set as the point at which the -Zimag value increases with an approximate 45° slope on the Nyquist diagram.

Next, a pulse charging current is applied to the battery 10 at a charging frequency higher than the diffusion resistance frequency to charge the battery 10 ( S300 ).

As described above, in order to prevent aging of the battery 10 due to diffusion of ions in the electrolyte during the charging process of the battery 10, a frequency higher than the diffusion resistance frequency at which diffusion of ions does not occur is set as the charging frequency of the pulse charging current. The battery 10 is charged by applying a pulse charging current to the battery 10 according to the set charging frequency.

The diffusion resistance frequency means a limiting frequency of the charging frequency, and the charging frequency may be determined in consideration of the charging time of the battery 10 among frequencies greater than the diffusion resistance frequency, which is the limiting frequency.

5 shows the pulse charging current of the battery 10 according to the present embodiment. Referring to FIG. 5 , the pulse of the pulse charging current may be charged by applying the pulse charging current in a rectangular pulse waveform in which the charging current is applied for a predetermined time and then the charging current is cut off for a predetermined time. As described above, in the state in which the charging current is cut off, the positive ions 18 gathered around the SEI 20 inside the battery 10 are charged while slowly penetrating between the SEI 20 in a state where the SEI 20 does not grow. The positive ions 18 move stably into the negative electrode material 12 .

As described above, since the pulse charging is performed at a charging frequency higher than the diffusion resistance frequency, aging of the battery 10 due to diffusion of ions in the electrolyte can be minimized, and thus high-current pulse charging is possible. That is, the battery 10 may be charged with a high current of 1C (C-rate) or higher while minimizing the aging of the battery 10 .

C-rate (Current rate) refers to the ratio of the current to be charged and discharged with respect to the capacity of the battery 10 . The higher the C-rate, the higher the C-rate means that the battery 10 of the same capacity can be charged with a high current. According to the present invention, since pulse charging by a high current of 1C or more is possible, fast charging of the battery 10 is possible. For example, when the charging current is applied, the pulse charging may be performed at 6C and at 0C during the rest period.

As shown in FIG. 5 , constant current charging may be performed by applying a constant current to the battery 10 before applying the pulse charging current to the battery 10 . In a section in which the voltage of the battery 10 is very low, constant current charging can be performed through constant current control by a low voltage. The constant current charging is continued at a low voltage, and then the battery 10 voltage is set to a preset voltage value (eg, a battery cell). (maximum charging voltage), it can be switched to pulse charging.

6 shows a modified example of the pulse charging current application form of the battery charging method according to the present embodiment.

This modified example is a method of applying the pulse charging current while lowering or increasing the pulse charging current in stages without performing constant current charging in the initial stage of charging.

When a pulse charging current is applied to the battery, a charging voltage is formed in each cell of the battery. In this modified example, as shown in FIG. 6 , the battery cell reaches the maximum charging voltage during initial high-current pulse charging. In this case, the pulse charging current is applied to the battery by gradually lowering or increasing the pulse charging voltage so as to be maintained below the maximum charging voltage of the battery cell.

For example, if pulse charging with a high current of about 6C is performed at the initial stage of charging, the charging voltage is gradually increased and the maximum charging voltage of the battery cell is reached. Thereafter, the pulse charging current may be lowered and applied to about 5C so as to be maintained below the maximum charging voltage of the battery cell, and then the pulse charging current may be applied to the battery by gradually lowering or increasing it according to the state of charge of the battery.

Heat generation of the battery can be minimized by continuously tracking the charging voltage of the battery cell during charging of the battery and charging the battery while gradually lowering or increasing the pulse charging current so that it is maintained below the maximum charging voltage.

The maximum charging voltage of a battery cell is to prevent overcharging of the battery. For lithium-ion electricity, 4.2V or 4.3V is suggested as the maximum charging voltage, but the maximum charging voltage may be set differently depending on the type of battery and the battery manufacturer. have.

7 is a block diagram of a battery charging device 22 according to another embodiment of the present invention, and FIG. 8 is a configuration diagram of an electric vehicle charging system having a battery charging device 22 according to another embodiment of the present invention. to be.

7 and 8, the charging device 22, the charging connector 24, the charging device body 26, the battery state information measuring unit 28, the AC power supply unit 30, the impedance measuring unit 32, the charging frequency A setting unit 34 , a pulse charging unit 36 , and an electric vehicle 38 are shown.

The battery charging device 22 according to the present embodiment includes a charging device body 26 having a charging connector 24 electrically connected to a terminal of the battery 10; The AC power supply unit 30 for applying alternating currents of different frequencies to the battery 10, the impedance measuring unit 32 for measuring the impedance for each frequency according to the application of the alternating current, and the battery ( a battery state information measuring unit 28 including a charging frequency setting unit 34 for setting the frequency of the alternating current at which chemical diffusion starts in 10) as a diffusion resistance frequency; It is provided in the charging device body 26 and includes a pulse charging unit 36 for charging the battery 10 by applying a pulse charging current to the battery 10 at a charging frequency higher than the diffusion resistance frequency.

The battery charging device 22 according to the present embodiment is a device for charging a battery 10 capable of charging and discharging, that is, a secondary battery, and is installed in various electronic devices such as an electric vehicle 38 and a smart phone. You can charge the battery.

The battery 10 according to the present embodiment includes a secondary battery capable of charging electrons, such as a lead acid battery, a nickel cadmium battery, a lithium polymer battery, a lithium ion battery, a nickel hydrogen battery, and the like. Among them, a lithium ion battery has no memory phenomenon and has good battery output, and thus a lot of research and development has been made recently. Hereinafter, a battery charging method will be described in detail focusing on the lithium ion battery 10 .

7 and 8 show a charging system for charging the battery 10 built in the electric vehicle 38. The battery charging device 22 according to the present embodiment is installed in the electric vehicle charging system to the electric vehicle. It is possible to charge the battery 10 built in (38).

The charging device body 26 has a charging connector 24 electrically connected to a terminal of the battery 10 . The charging device main body 26 is a main body for supplying power to the electric vehicle 38 or the battery 10 of the smartphone through the charging connector 24, and operates a display for indicating a charging state and the charging device 22 A control panel may be installed for this purpose.

In the case of the electric vehicle charging system, a vehicle number recognizer capable of recognizing the vehicle number of the electric vehicle 38 , an unmanned fee settlement system, etc. are installed to charge the user of the electric vehicle 38 .

The charging connector 24 is electrically connected to a terminal of the battery 10 to supply a charging current from the charging device body 26 to the battery 10 . The charging connector 24 may extend through a charging cable for charging of the electric vehicle and be connected to the battery of the electric vehicle 38 , and in the case of an electronic device such as a smartphone, may be connected to a terminal of the battery in the form of a terminal.

The battery state information measurement unit 28 is for setting a diffusion resistance frequency suitable for the battery 10 according to the state of the battery, and includes an AC power supply unit 30 , an impedance measurement unit 32 , and a charging frequency setting unit 34 . ) and set the diffusion resistance frequency of the battery 10 .

The battery state information measuring unit 28 may be built into the charging device 22 or configured separately from the charging device 22 to set the diffusion resistance frequency for the battery 10 as in the present embodiment.

The diffusion resistance frequency of the battery obtained by the battery state information measurement unit 28 may be a diffusion resistance frequency for a battery of the same type as the battery to be charged. With respect to the battery 10 of the same model through the measurement unit 28, it is possible to acquire in advance the diffusion resistance frequency of the battery model.

The AC power supply unit 30 sequentially applies AC currents of different frequencies to the battery 10 . AC current of different frequencies is sequentially applied to the battery 10 to measure the amplitude and phase change of the response according to each frequency, and the impedance for each frequency of the applied AC current is measured. ), apply alternating currents of different frequencies.

The impedance measuring unit 32 measures the impedance for each frequency according to the application of the alternating current. Impedance can be measured through an impedance measuring device (LCR meter), and in the process of measuring impedance, resistance R, capacitance C, and inductance L of impedance for each frequency can be calculated.

The resistance, capacitance, and inductance of the impedance for each frequency may be displayed on an impedance complex plane called a Nyquist plot, which will be described later, and may be expressed as a graph by connecting the indicated points. In this case, the impedance measuring unit 32 may calculate the impedance according to the electrochemical impedance spectroscopy method.

The charging frequency setting unit 34 sets the frequency of the alternating current at which chemical diffusion starts in the battery 10 as the diffusion resistance frequency from the measured impedance for each frequency.

If the analysis of the measured impedance for each frequency is performed, the electrochemical reaction occurring between the two electrodes and the electrolyte present inside the battery 10 can be modeled and analyzed in the form of an equivalent electric circuit, the Nyquist diagram This can be interpreted from

Since the diffusion rate of ions in the electrolyte is relatively slow, the effect is insignificant at high frequencies and the characteristics appear at low frequencies. It is defined as the diffusion resistance frequency, and by applying the pulse charging current at a charging frequency higher than the diffusion storage frequency during pulse charging, it is possible to prevent aging of the battery 10 due to diffusion of ions in the electrolyte during the charging process.

The above-described AC power supply unit 30 , impedance measuring unit 32 , and charging frequency setting unit 34 are built into the charging device body 26 or are configured as a separate device outside the charging device body 26 , and the battery For (10), the impedance can be measured according to electrochemical impedance spectroscopy, and the diffusion resistance frequency can be set from the measured impedance for each frequency.

When the AC power supply unit 30 , the impedance measuring unit 32 , and the charging frequency setting unit 34 are located outside the charging device body 26 , the set diffusion resistance frequency is transmitted to the charging device body 26 through a wireless communication unit (not shown). ) or stored in the memory of the charging device in advance.

The pulse charging unit 36 is provided in the charging device body 26 and applies a pulse charging current to the battery 10 at a charging frequency higher than the diffusion resistance frequency.

When the diffusion resistance frequency for the battery 10 is set in the charging frequency setting unit 34 , the pulse charging power supply unit applies a pulse charging current to the battery 10 at a charging frequency of a frequency higher than the diffusion resistance frequency to the battery 10 . Pulse charging is performed for

In order to prevent aging of the battery 10 due to diffusion of ions in the electrolyte during the charging process of the battery 10, a frequency higher than the diffusion resistance frequency at which diffusion of ions does not occur is set as the charging frequency of the pulse charging current, and the charging frequency is set. A pulse charging current is applied to the battery 10 according to the frequency to charge the battery 10 .

The diffusion resistance frequency means a limiting frequency of the charging frequency, and the charging frequency may be determined in consideration of the charging time of the battery 10 among frequencies greater than the diffusion resistance frequency, which is the limiting frequency.

The pulse of the pulse charging current may be charged by applying the pulse charging current in a rectangular pulse waveform in which the charging current is applied for a predetermined time and then the charging current is cut off for a predetermined time.

On the other hand, as described above, since pulse charging is performed at a charging frequency higher than the diffusion resistance frequency, aging of the battery 10 due to diffusion of ions in the electrolyte can be minimized, and thus high-current pulse charging is possible. . That is, the battery 10 may be charged with a high current of 1C (C-rate) or higher while minimizing the aging of the battery 10 . According to the present invention, since pulse charging by a high current of 1C or more is possible, fast charging of the battery 10 is possible.

Although the above has been described with reference to the embodiments of the present invention, those of ordinary skill in the art may variously modify the present invention within the scope not departing from the spirit and scope of the present invention described in the claims below. and can be changed.

10: battery 12: anode material
14: separator 16: cathode material
18: cation 20: SEI
22: charging device 24: charging connector
26: main body of the charging device 28: battery state information measurement unit
30: AC power supply unit 32: impedance measuring unit
34: charging frequency setting unit 36: pulse charging unit
38: electric vehicle

Claims (19)

measuring impedance for each frequency by sequentially applying alternating currents of different frequencies to the battery;
setting a frequency of the alternating current at which chemical diffusion in the battery starts from the measured impedance for each frequency as a diffusion resistance frequency;
and charging the battery by applying a pulse charging current to the battery at a charging frequency higher than the diffusion resistance frequency.
According to claim 1,
The battery is
A method of charging a battery, characterized in that it is a lithium ion battery.
According to claim 1,
The pulse charging current, 1C (C-rate) or more, characterized in that the battery charging method.
According to claim 1,
The pulse of the pulse charging current is,
A method for charging a battery, characterized in that it is a rectangular pulse waveform that intermittently interrupts the charging current.
According to claim 1,
Before charging the battery by applying the pulse charging current to the battery,
Further comprising the step of applying a constant current to the battery to perform constant current charging, the battery charging method.
According to claim 1,
The step of charging the battery,
The method of charging a battery, characterized in that charging while lowering or increasing the pulse charging current in stages so that the charging voltage of the battery cell is maintained below a preset maximum charging voltage of the battery cell.
According to claim 1,
Measuring the impedance for each frequency comprises:
Calculating resistance R, capacitance C, and inductance L of the impedance for each frequency by sequentially applying an alternating current from a high frequency to a low frequency to the battery , how to charge the battery.
8. The method of claim 7,
Measuring the impedance for each frequency comprises:
The method further comprising the step of creating a Nyquist Plot according to the resistance (resistance) R, the capacitance (capacitance) C, and the inductance (inductance) L of the impedance for each frequency, characterized in that the battery charging method.
9. The method of claim 8,
Setting the diffusion resistance frequency of the alternating current comprises:
and setting the frequency of the alternating current at which chemical diffusion starts in the Nyquist diagram as the diffusion resistance frequency.
10. The method of claim 9,
The starting point of the chemical diffusion is,
The battery charging method, characterized in that it is the starting point of the Warburg impedance (Warburg Impedance) in the Nyquist diagram.
a charging device body having a charging connector electrically connected to a terminal of the battery;
An AC power supply unit for applying alternating currents of different frequencies to the battery, an impedance measuring unit for measuring impedance for each frequency according to the application of the alternating current, and an impedance measuring unit for measuring the impedance for each frequency according to the measured impedance for each frequency in which chemical diffusion is started in the battery a battery state information measuring unit including a charging frequency setting unit for setting the frequency of the alternating current to a diffusion resistance frequency;
and a pulse charging unit provided in the charging device body and charging the battery by applying a pulse charging current to the battery at a charging frequency higher than the diffusion resistance frequency.
12. The method of claim 11,
The battery is
A battery charging device, characterized in that it is a lithium ion battery.
12. The method of claim 11,
The pulse charging current, 1C (C-rate) or more, characterized in that the battery charging device.
12. The method of claim 11,
The pulse of the pulse charging current is,
A battery charging device, characterized in that it is a rectangular pulse waveform for intermitting the alternating current.
12. The method of claim 11,
The pulse charging power supply unit,
Before applying the pulse charging current to the battery, a constant current is applied to the battery to perform constant current charging.
12. The method of claim 11,
The pulse charging power supply unit,
The battery charging device, characterized in that the charging voltage of the battery cell is lowered or increased in stages such that the preset maximum charging voltage of the battery cell is maintained below or lowering or increasing the pulse charging current.
12. The method of claim 11,
The impedance measuring unit,
A battery charging device, characterized in that by sequentially applying an alternating current from a high frequency to a low frequency to the battery to calculate a resistance R, a capacitance, and an inductance L of the impedance for each frequency.
18. The method of claim 17,
The impedance measuring unit,
Prepare a Nyquist Plot according to the resistance (resistance) R, capacitance (capacitance) C, and inductance (inductance) L of the impedance for each frequency,
The charging frequency setting unit,
The battery charging device, characterized in that the frequency of the alternating current at which chemical diffusion starts in the Nyquist diagram is set to the diffusion resistance frequency.
19. The method of claim 18,
The starting point of the chemical diffusion is,
The battery charging device, characterized in that it is the starting point of the Warburg impedance (Warburg Impedance) in the Nyquist diagram.

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