Method for charging a battery

Abstract

According to various embodiments, a method for charging a battery is provided. The method for charging a battery includes the following steps: performing a first constant current charging of the battery with a constant current having a first intensity until the voltage of the battery rises above a first voltage level; performing a second constant current charging of the battery with a constant current having a second intensity until the voltage of the battery rises above a second voltage level; performing a third constant current charging of the battery with a constant current having a third intensity until the voltage of the battery rises above a third voltage level; and performing a constant voltage charging of the battery with a constant voltage having a third voltage level until the charging current of the battery drops to a fourth intensity.

Description

[0001] This application claims the benefit of Korean Patent Application No. 10-2020-0011345 filed on January 30, 2020, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0002] One or more embodiments relate to a method for charging a battery, and more particularly, to a method for charging a battery, whereby a charging time of the battery can be reduced. Background Art

[0003] Typically, lithium-ion battery charging devices charge the battery using a constant current (CC) / constant voltage (CV) charging method. For example, when the battery voltage is less than or equal to a reference voltage level Vref (e.g., 4.4V), the battery is charged with a constant current of a preset intensity I1 (e.g., a 1.5C rate). When the battery voltage reaches the reference voltage level Vref, the battery is charged with a constant voltage of the reference voltage level Vref.

[0004] like Figure 1 As shown in , the charging current curve is constant until time t1 when the battery voltage is less than or equal to the reference voltage level Vref, and then decreases exponentially after time t1. The battery voltage curve increases as a logarithmic function until time t1, and remains at a constant level when the battery voltage reaches the reference voltage level Vref. When the charging current flowing through the battery gradually decreases and reaches time t2 (the charging current reaches a preset intensity If (e.g., 0.05C rate) at time t2), it is determined that the battery is fully charged, and charging is stopped. The state of charge (SOC) of the battery is shown as increasing from 0 to 100%. When the SOC of the battery is 0, the battery voltage is at the initial level Vi, and when the SOC of the battery is 100%, the open circuit voltage of the battery is the reference voltage level Vref.

[0005] The disadvantage of this charging method is that the battery charging time becomes longer due to the characteristics of the battery in the constant voltage charging section (from time t1 to time t2), resulting in a longer total charging time. In addition, when the battery system is operated in conjunction with the power system, excessive heat may be generated inside the battery cell. In addition, the softening phenomenon of the positive electrode plate (the phenomenon of electrolyte flowing out and adhering to the electrode plate) occurs due to overheating, and the battery life is shortened. Summary of the Invention

[0006] One or more embodiments include new methods for charging a battery, whereby the charging time of the battery may be reduced and the life of the battery may be increased.

[0007] Additional aspects will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the presented disclosed embodiments.

[0008] According to one or more embodiments, a method for charging a battery includes the following steps: performing a first constant-current charging of the battery with a constant current having a first intensity, and then ending the constant-current charging with the first intensity when the voltage of the battery rises above the first voltage level; after performing the first constant-current charging, performing a second constant-current charging of the battery with a constant current having a second intensity smaller than the first intensity, and then ending the constant-current charging with the second intensity when the voltage of the battery rises above a second voltage level higher than the first voltage level; after performing the second constant-current charging, performing a third constant-current charging of the battery with a constant current having a third intensity smaller than the second intensity, and then ending the constant-current charging with the third intensity when the voltage of the battery rises above a third voltage level higher than the second voltage level; and after performing the third constant-current charging, performing constant-voltage charging of the battery with a constant voltage having a third voltage level, and then ending the constant-voltage charging with the third voltage level when the charging current of the battery drops to a fourth intensity smaller than the third intensity.

[0009] The second voltage level may be set equal to a buffer voltage level of the battery.

[0010] As the third voltage level is set greater than the buffer voltage level of the battery, the fourth strength may be set greater.

[0011] The first intensity may be set to an intensity corresponding to a charge rate greater than or equal to 1.25C and less than or equal to 2.0C. The second intensity may be set to an intensity corresponding to a charge rate greater than or equal to 1.0C and less than or equal to 1.25C. The third intensity may be set to an intensity corresponding to a charge rate greater than or equal to 0.5C and less than or equal to 1.0C.

[0012] The first intensity may be set to an intensity corresponding to a 1.5C magnification, the second intensity may be set to an intensity corresponding to a 1.2C magnification, and the third intensity may be set to an intensity corresponding to a 1.0C magnification.

[0013] The first intensity may be set to an intensity corresponding to a 1.5C magnification, the second intensity may be set to an intensity corresponding to a 1.0C magnification, and the third intensity may be set to an intensity corresponding to a 0.5C magnification.

[0014] The first voltage level may be set to a value within a range of 0.95 to 0.98 times the buffer voltage level. The third voltage level may be set to a value within a range of 1.005 to 1.02 times the buffer voltage level.

[0015] The first voltage level may be set to a value obtained by subtracting a voltage level within a range of 0.1V to 0.2V from the buffer voltage level. The third voltage level may be set to a value obtained by adding a voltage level within a range of 0.02V to 0.1V to the buffer voltage level.

[0016] When the third voltage level is set to a value obtained by adding 0.03 V to the buffer voltage level, the fourth intensity may be set to an intensity corresponding to a rate of 0.15 C. When the third voltage level is set to a value obtained by adding 0.05 V to the buffer voltage level, the fourth intensity may be set to an intensity corresponding to a rate of 0.2 C.

[0017] The method may further include the following steps: between the first constant current charging and the second constant current charging, performing a fourth constant current charging of the battery with a constant current having a fourth intensity smaller than the first intensity and larger than the second intensity, and then ending the constant current charging with the fourth intensity when the voltage of the battery rises to above a fourth voltage level that is higher than the first voltage level and lower than the second voltage level.

[0018] The method may further include the following steps: between the second constant current charging and the third constant current charging, performing a fourth constant current charging of the battery with a constant current having a fourth intensity smaller than the second intensity and larger than the third intensity, and then ending the constant current charging with the fourth intensity when the voltage of the battery rises to above a fourth voltage level that is higher than the second voltage level and lower than the third voltage level.

[0019] The method may further include the following steps: stopping charging of the battery for a preset time between the first constant current charging and the second constant current charging; stopping charging of the battery for a preset time between the second constant current charging and the third constant current charging; and stopping charging of the battery for a preset time between the third constant current charging and the constant voltage charging.

[0020] Example embodiments will be described in more detail with reference to the accompanying drawings so that features will be apparent to those skilled in the art. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above and other aspects, features and advantages of certain disclosed embodiments will become more apparent from the following description taken in conjunction with the accompanying drawings, in which:

[0022] Figure 1 is a graph showing changes in charging current intensity and battery voltage level when a battery is charged by using a constant current / constant voltage charging method according to the related art;

[0023] Figure 2 A charging device for charging a battery by using a method for charging a battery according to an embodiment is shown;

[0024] Figure 3 is a flow chart illustrating a method for charging a battery according to an embodiment;

[0025] Figure 4 is a graph showing changes in charging current intensity and battery voltage level when a battery is charged by using a method for charging a battery according to an embodiment; and

[0026] Figure 5 is a graph showing changes in charging current intensity and battery voltage level when a battery is charged by using a method for charging a battery according to another embodiment. DETAILED DESCRIPTION

[0027] Reference will now be made in detail to the embodiments, examples of which are shown in the accompanying drawings, in which like reference numerals always represent like elements. In this regard, the present embodiments may have different forms and should not be construed as being limited to the description set forth herein. Therefore, the embodiments are described below only by reference to the accompanying drawings to explain aspects of this specification. As used herein, the term "and / or" includes any and all combinations of one or more of the relevant listed items. When a statement such as "at least one of..." is located after a column of elements, it modifies the entire column of elements without modifying the individual elements in the column.

[0028] Example embodiments will now be described in more detail with reference to the accompanying drawings. However, example embodiments may be implemented in many forms and should not be considered limited to the embodiments described herein. Rather, these embodiments are provided to complete the disclosure and to fully inform those skilled in the art of the disclosure of the scope of the disclosure.

[0029] The terms used in this application are only used to describe specific embodiments and are not intended to limit the present disclosure. As used herein, the singular "one (kind / person)" and "said (the)" are intended to also include plural forms, unless the context clearly indicates otherwise. It will also be understood that the terms "include" and / or "comprising" used herein illustrate the presence of stated features or components, but do not exclude the presence or addition of one or more other features or components. It will be understood that although the terms "first", "second" etc. can be used here to describe various components, these components should not be limited by these terms. These terms are only used to distinguish a component from other components.

[0030] Hereinafter, the embodiments will be described more fully with reference to the accompanying drawings showing example embodiments. Throughout the specification, the same reference numerals represent the same components. Regardless of the figure numbers, those components that are the same or corresponding are given the same reference numerals, and redundant descriptions thereof are omitted.

[0031] In the present disclosure, the battery may be charged with a charging current having a reference intensity Iref, and the reference intensity Iref may be an intensity corresponding to a 1C rate. For example, when the battery capacity is 2000 mAh, the reference intensity Iref may be an intensity corresponding to a 1C rate (i.e., 2 A).

[0032] The battery can be charged to a voltage of a reference charge level Vref. When the battery is fully charged, the reference charge level Vref may be the same as the level of the open circuit voltage. The reference charge level Vref may be referred to as a buffer voltage level. The charging device according to the prior art may apply a charging voltage of the reference charge level Vref to the battery in the constant voltage charging section (e.g., Figure 1 ).

[0033] Figure 2 A charging device for charging a battery by using the method for charging a battery according to an embodiment is shown. Figure 3 is a flowchart illustrating a method for charging a battery according to an embodiment. Figure 4 is a graph showing changes in charging current intensity and battery voltage level when a battery is charged by using a method for charging a battery according to an embodiment.

[0034] Reference Figures 2 to 4 , the charging device 200 may charge the battery 100 by using the method for charging a battery according to an embodiment.

[0035] The charging device 200 can charge the battery 100 by using a method for charging the battery 100, the method including: performing a first constant current charging on the battery 100 with a constant current having a first intensity I1, and then ending the constant current charging with the first intensity I1 when the voltage of the battery 100 rises to or above a first voltage level V1 (operation S10); after performing the first constant current charging (operation S10), performing a second constant current charging on the battery 100 with a constant current having a second intensity I2 smaller than the first intensity I1, and then ending the constant current charging with the second intensity I2 when the voltage of the battery 100 rises to or above a second voltage level V2 higher than the first voltage level V1 (operation S11). After the second constant-current charging (operation S20) is performed, the battery 100 is subjected to a third constant-current charging with a constant current having a third intensity I3 smaller than the second intensity I2, and then the constant-current charging with the third intensity I3 is terminated when the voltage of the battery 100 rises to or above a third voltage level V3 higher than the second voltage level V2 (operation S30); after the third constant-current charging (operation S30) is performed, the battery 100 is subjected to constant-voltage charging with a constant voltage having a third voltage level V3, and then the constant-voltage charging with the third voltage level V3 is terminated when the charging current of the battery 100 drops to a fourth intensity If smaller than the third intensity I3 (operation S40).

[0036] According to an embodiment, the second voltage level V2 may be set equal to the reference charge level Vref. When the battery 100 is fully charged, the second voltage level V2 may be set equal to the open circuit voltage level of the battery 100. The second voltage level V2 may be set equal to the buffer voltage level of the battery 100.

[0037] According to an embodiment, the third intensity I3 may be set to be equal to the reference intensity Iref. The third intensity I3 may be set to an intensity corresponding to a 1C magnification.

[0038] In this specification, it is assumed that the second voltage level V2 is set equal to the reference charge level Vref and the third intensity I3 is set equal to the reference intensity Iref. However, this is merely an example, and the second voltage level V2 may be larger or smaller than the reference charge level Vref due to a slight error, and the third intensity I3 may be larger or smaller than the reference intensity Iref due to a slight error.

[0039] The present disclosure will be described based on the assumption that the battery 100 is substantially fully discharged before performing the first constant current charging (operation S10). However, the battery 100 may not be fully discharged. Even in this case, the charging device 200 can sequentially perform the above operations S10 to S40. However, depending on the remaining capacity of the battery 100, the first constant current charging (operation S10) may not be substantially performed, or may be performed only for a very short time.

[0040] In the first constant current charging (operation S10), the charging device 200 may charge the battery 100 with a constant current having a first intensity I1. The first intensity I1 may be greater than the reference intensity Iref. According to an example, the first intensity I1 may be set to an intensity corresponding to a charging rate greater than or equal to 1.25C and less than or equal to 2.0C. For example, the first intensity I1 may be set to an intensity corresponding to a 1.5C rate.

[0041] When the voltage of the battery 100 rises above the first voltage level V1 at time t1a, the charging device 200 may end constant current charging with the first intensity I1. The first voltage level V1 may be lower than the reference charge level Vref. According to an example, the first voltage level V1 may be set to a value within a range of 0.95 to 0.98 times the reference charge level Vref. According to another example, the first voltage level V1 may be set to a value obtained by subtracting a voltage level within a range of 0.1V to 0.2V from the buffer voltage level. For example, when the reference charge level Vref is 4.4V, the first voltage level V1 may be set to 4.2V, 4.25V, or 4.3V.

[0042] In the second constant current charge (operation S20) after the first constant current charge (operation S10), the charging device 200 may charge the battery 100 with a constant current having a second intensity I2. The second intensity I2 may be lower than the first intensity I1. According to an example, the second intensity I2 may be set to an intensity corresponding to a charge rate greater than or equal to 1.0C and less than or equal to 1.25C. For example, the second intensity I2 may be set to an intensity corresponding to a 1.2C rate. For example, the second intensity I2 may be set to an intensity corresponding to a 1.0C rate.

[0043] When the voltage of the battery 100 rises above the second voltage level V2 at time t1b, the charging device 200 may end the constant current charging with the second intensity I2. The second voltage level V2 may be higher than the first voltage level V1 and may be set equal to the reference charging level Vref.

[0044] According to another example, between the first constant current charging (operation S10) and the second constant current charging (operation S20), the charging of the battery 100 may be stopped for a preset time. According to an example, for example, the preset time may be selected within the range of 5 minutes to 20 minutes. For example, the preset time may be set to 10 minutes. The preset time may vary depending on the temperature of the battery 100.

[0045] In the third constant current charge (operation S30) after the second constant current charge (operation S20), the charging device 200 may charge the battery 100 with a constant current having a third intensity I3. The third intensity I3 may be lower than the second intensity I2. The third intensity I3 may be set equal to the reference intensity Iref. According to an example, the third intensity I3 may be set to an intensity corresponding to a charge rate greater than or equal to 0.5C and less than or equal to 1.0C. For example, the third intensity I3 may be set to an intensity corresponding to a 1.0C rate. For example, the third intensity I3 may be set to an intensity corresponding to a 0.5C rate.

[0046] When the voltage of the battery 100 rises above the third voltage level V3 at time t1c, the charging device 200 may terminate constant current charging with the third intensity I3. The third voltage level V3 may be higher than the reference charge level Vref. According to an example, the third voltage level V3 may be set to a value within a range of 1.005 to 1.02 times the reference charge level Vref. According to another example, the third voltage level V3 may be set to a value obtained by adding a voltage level within a range of 0.02V to 0.1V to the buffer voltage level. For example, when the reference charge level Vref is 4.4V, the third voltage level V3 may be set to 4.43V or 4.45V.

[0047] According to another example, between the second constant current charging (operation S20) and the third constant current charging (operation S30), the charging of the battery 100 may be stopped for a preset time. According to an example, for example, the preset time may be selected within the range of 5 minutes to 20 minutes. For example, the preset time may be set to 10 minutes. The preset time may vary depending on the temperature of the battery 100.

[0048] During constant voltage charging (operation S40) following the third constant current charging (operation S30), the charging device 200 may charge the battery 100 with a constant voltage having a third voltage level V3. When the charging current of the battery 100 drops to a fourth intensity If at time t2, the charging device 200 may terminate the constant voltage charging having the third voltage level V3. The fourth intensity If may be lower than the third intensity I3. In an example, the fourth intensity If may be set to be lower than the intensity corresponding to a 0.3C rate. The fourth intensity If may be understood as the end-of-charge current intensity.

[0049] The fourth intensity If can be set to be larger as the difference between the third voltage level V3 and the reference charge level Vref increases. For example, when the reference charge level Vref is set to 4.4V and the third voltage level V3 is set to 4.43V, the fourth intensity If can be set to an intensity corresponding to a 0.15C rate. When the reference charge level Vref is set to 4.4V and the third voltage level V3 is set to 4.45V, the fourth intensity If can be set to an intensity corresponding to a 0.20C rate.

[0050] As the difference between the third voltage level V3 and the reference charge level Vref increases, the fourth intensity If may be set larger, so that the charging speed of the battery 100 may be increased and overvoltage charging of the battery 100 may be prevented.

[0051] According to another embodiment, between the third constant current charging (operation S30) and the constant voltage charging (operation S40), the charging of the battery 100 may be stopped for a preset time. According to an example, for example, the preset time may be selected within the range of 5 minutes to 20 minutes. For example, the preset time may be set to 10 minutes. The preset time may vary depending on the temperature of the battery 100.

[0052] Hereinafter, the time required to charge the battery 100 having a reference charge level Vref of 4.4 V by using a charging method according to the related art will be compared with the time required to charge the battery 100 having a reference charge level Vref of 4.4 V by using a charging method according to various examples of the present disclosure. The battery 100 may be a lithium cobalt oxide (LCO) battery cell having a rated voltage of 3.85 V.

[0053] When using the Figure 1 When the battery 100 is charged using the conventional charging method shown in FIG (i.e., after constant current charging at an intensity corresponding to a 1.5C rate, when the battery voltage reaches 4.4V and constant voltage charging at 4.4V is performed), it takes 88 minutes to fully charge the battery 100. The constant current charging time is 19 minutes, and the constant voltage charging time is 69 minutes.

[0054] When the battery 100 is charged using the charging method according to the embodiment, according to various examples, it takes 61 to 68 minutes to fully charge the battery 100. The first intensity I1, the second intensity I2, and the third intensity I3 are set to intensities corresponding to a 1.5C rate, a 1.2C rate, and a 1.0C rate, respectively.

[0055] According to an example, when the first voltage level V1 and the third voltage level V3 are set to 4.2V and 4.43V, respectively, and the end-of-charge current intensity If is set to an intensity corresponding to a 0.15C rate, the total constant-current charging time is 33 minutes, and the constant-voltage charging time is 35 minutes. In other words, it takes 68 minutes to fully charge the battery 100.

[0056] According to another example, when the first voltage level V1 and the third voltage level V3 are set to 4.2V and 4.45V, respectively, and the end-of-charge current intensity If is set to an intensity corresponding to a 0.20C rate, the total constant-current charging time is 35 minutes, and the constant-voltage charging time is 28 minutes. In other words, it takes 63 minutes to fully charge the battery 100.

[0057] According to another example, when the first voltage level V1 and the third voltage level V3 are set to 4.25V and 4.43V, respectively, and the end-of-charge current intensity If is set to an intensity corresponding to a 0.15C rate, the total constant-current charging time is 32 minutes, and the constant-voltage charging time is 36 minutes. In other words, it takes 68 minutes to fully charge the battery 100.

[0058] According to another example, when the first voltage level V1 and the third voltage level V3 are set to 4.25V and 4.45V, respectively, and the end-of-charge current intensity If is set to an intensity corresponding to a 0.20C rate, the total constant-current charging time is 33 minutes, and the constant-voltage charging time is 29 minutes. In other words, it takes 62 minutes to fully charge the battery 100.

[0059] According to another example, when the first voltage level V1 and the third voltage level V3 are set to 4.3V and 4.43V, respectively, and the end-of-charge current intensity If is set to an intensity corresponding to a 0.15C rate, the total constant-current charging time is 31 minutes, and the constant-voltage charging time is 36 minutes. In other words, it takes 67 minutes to fully charge the battery 100.

[0060] According to another example, when the first voltage level V1 and the third voltage level V3 are set to 4.3V and 4.45V, respectively, and the end-of-charge current intensity If is set to an intensity corresponding to a 0.20C rate, the total constant-current charging time is 32 minutes, and the constant-voltage charging time is 29 minutes. In other words, it takes 61 minutes to fully charge the battery 100.

[0061] Thus, according to various examples, the time required to fully charge the battery 100 is reduced by approximately 20% to approximately 30% compared to conventional methods.

[0062] Figure 5is a graph showing changes in charging current intensity and battery voltage level when a battery is charged by using a charging method according to another embodiment.

[0063] Reference Figure 5 ,and Figure 3 and Figure 4 Compared with the charging method, Figure 5 The charging method includes the following steps except that the fourth constant current charging section between time t1c and time t1d is included: Figure 3 and Figure 4 The charging methods are basically the same. The same parts will not be repeated.

[0064] In the fourth constant current charge after the third constant current charge (operation S20), the charging device 200 may charge the battery 100 with a constant current having a fourth intensity I4. The fourth intensity I4 may be lower than the third intensity I3. According to an example, the fourth intensity I4 may be set to an intensity corresponding to a charge rate greater than or equal to 0.4C and less than or equal to 0.8C. For example, the fourth intensity I4 may be set to an intensity corresponding to a 0.7C rate. For example, the fourth intensity I4 may be set to an intensity corresponding to a 0.5C rate.

[0065] When the voltage of the battery 100 rises above the fourth voltage level V4 at time t1d, the charging device 200 may terminate constant current charging with the fourth intensity I4. The fourth voltage level V4 may be higher than the reference charge level Vref. According to an example, the fourth voltage level V4 may be set to a value within a range of 1.02 to 1.05 times the reference charge level Vref. According to another example, the fourth voltage level V4 may be set to a value obtained by adding a voltage level within a range of 0.05V to 0.2V to the buffer voltage level. For example, when the reference charge level Vref is 4.4V, the fourth voltage level V4 may be set to 4.48V or 4.5V.

[0066] According to another example, between the third constant-current charging (operation S30 ) and the fourth constant-current charging, charging of the battery 100 may be stopped for a preset time.

[0067] In constant voltage charging (operation S40) after performing the fourth constant current charging, the charging device 200 may charge the battery 100 with a constant voltage having a fourth voltage level V4. When the charging current of the battery 100 drops to the fourth intensity If at time t2, the charging device 200 may end the constant voltage charging having the fourth voltage level V4.

[0068] According to another embodiment, Figure 3A fourth constant current charging may be performed between the first constant current charging (operation S10) and the second constant current charging (operation S20) in the charging method, and the charging device 200 may charge the battery 100 with a constant current having an intensity smaller than the first intensity I1 and larger than the second intensity I2. When the voltage of the battery 100 rises to a voltage level higher than the first voltage level V1 and lower than the second voltage level V2, the charging device 200 may end the constant current charging with the current intensity and perform the second constant current charging (operation S20).

[0069] According to another embodiment, Figure 3 A fourth constant current charging may be performed between the second constant current charging (operation S20) and the third constant current charging (operation S30) in the charging method, and the charging device 200 may charge the battery 100 with a constant current having an intensity smaller than the second intensity I2 and larger than the third intensity I3. When the voltage of the battery 100 rises to a voltage level higher than the second voltage level V2 and lower than the third voltage level V3, the charging device 200 may end the constant current charging with the current intensity and perform the third constant current charging (operation S30).

[0070] In the method for charging a battery according to various embodiments of the present disclosure, the lifespan of the battery may be extended and the charging time of the battery may be reduced.

[0071] The various embodiments of the present disclosure do not limit the scope of the present disclosure in any way. For the purpose of brevity, other functional aspects of conventional electronic devices, control systems, software development and systems (and components in the independent operating components of the system) may not be described in detail. In addition, the connecting lines or connectors shown in the various figures presented are intended to represent the exemplary functional relationships and / or physical or logical combinations between the various elements. It should be noted that many alternative relationships or additional functional relationships, physical connections or logical connections may be present in the implementation device. In addition, unless an element is specifically described as "necessary" or critical, no project or assembly is essential for the practice of the present disclosure.

[0072] In the specification sheets (particularly, claims) of the embodiments, the use of the terms "one (kind / person)" and "described (the)" and similar indicators in the context of describing the present disclosure (especially in the context of claims) will be interpreted as covering both the singular and the plural. In addition, unless otherwise noted herein, the enumeration of numerical ranges here is only intended to be used as a shorthand method for referring to each individual value falling within the range, and each individual value is included in the specification sheets as if it were individually narrated here. Finally, unless otherwise noted herein or unless clearly contradicted by the context, the steps of all methods described herein can be performed in any suitable order. The present disclosure need not be limited according to the order of description of the steps. Unless otherwise stated, the use of any example and all examples or exemplary language (e.g., "such as") provided herein is only intended to better explain the invention, and does not limit the scope of the invention. Without departing from the spirit and scope of the present invention, many modifications and adaptations will be apparent to those skilled in the art.

[0073] It should be understood that the embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each embodiment should generally be considered applicable to other similar features or aspects in other embodiments. Although one or more embodiments have been described with reference to the accompanying drawings, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the disclosure as defined by the claims.

Claims

1. A method for charging a battery, the method comprising the following steps: Performing a first constant current charge of the battery with a constant current having a first intensity, and then ending the constant current charge with the first intensity when the voltage of the battery rises above a first voltage level; After the first constant current charging is performed, the second constant current charging of the battery is performed with a constant current having a second intensity smaller than the first intensity, and then when the voltage of the battery rises to a second voltage level higher than the first voltage level, the charging with the constant current having the second intensity is terminated; After the second constant current charging is performed, the third constant current charging of the battery is performed with a constant current having a third intensity smaller than the second intensity, and then when the voltage of the battery rises to a third voltage level higher than the second voltage level, the charging with the constant current having the third intensity is terminated; as well as After the third constant current charging is performed, the constant voltage charging of the battery is performed with a constant voltage having a third voltage level, and then when the charging current of the battery drops to a fourth intensity that is smaller than the third intensity, the constant voltage charging with the third voltage level is terminated, The first intensity is set to an intensity corresponding to a charging rate less than or equal to 2.0C, and the fourth intensity is set to an intensity corresponding to a charging rate greater than or equal to 0.15C.

2. The method according to claim 1, wherein: The second voltage level is set equal to the buffer voltage level of the battery.

3. The method according to claim 2, wherein: As the third voltage level is set greater than the buffer voltage level of the battery, the fourth strength is set greater.

4. The method according to claim 2, wherein: The first intensity is set to an intensity corresponding to a rate greater than or equal to 1.25C, The second intensity is set to an intensity corresponding to a charge rate greater than or equal to 1.0C rate and less than or equal to 1.25C rate, and The third intensity is set to an intensity corresponding to a charge rate that is greater than or equal to a 0.5 C rate and less than or equal to a 1.0 C rate.

5. The method according to claim 2, wherein: The first intensity is set to an intensity corresponding to a 1.5C rate, the second intensity is set to an intensity corresponding to a 1.2C rate, and the third intensity is set to an intensity corresponding to a 1.0C rate.

6. The method according to claim 2, wherein: The first intensity is set to an intensity corresponding to a 1.5C rate, the second intensity is set to an intensity corresponding to a 1.0C rate, and the third intensity is set to an intensity corresponding to a 0.5C rate.

7. The method according to claim 2, wherein: The first voltage level is set to a value within a range of 0.95 times to 0.98 times the buffer voltage level, and The third voltage level is set to a value within a range of 1.005 times to 1.02 times the buffer voltage level.

8. The method according to claim 2, wherein: The first voltage level is set to a value obtained by subtracting a voltage level in a range of 0.1V to 0.2V from the buffer voltage level, and The third voltage level is set to a value obtained by adding a voltage level within a range of 0.02V to 0.1V to the buffer voltage level.

9. The method according to claim 2, wherein: When the third voltage level is set to a value obtained by adding 0.03 V to the buffer voltage level, the fourth intensity is set to an intensity corresponding to a 0.15C rate, and When the third voltage level is set to a value obtained by adding 0.05 V to the buffer voltage level, the fourth intensity is set to an intensity corresponding to a 0.2C rate.

10. The method according to any one of claims 1 to 9, further comprising the following steps: Between the first constant current charging and the second constant current charging, the battery is charged with a fourth constant current having an intensity smaller than the first intensity and larger than the second intensity, and then when the battery voltage rises to above a fourth voltage level that is higher than the first voltage level and lower than the second voltage level, the charging with the constant current is terminated.

11. The method according to any one of claims 1 to 9, further comprising the following steps: Between the second constant current charging and the third constant current charging, the battery is charged with a fourth constant current having an intensity smaller than the second intensity and larger than the third intensity, and then when the battery voltage rises to above a fourth voltage level that is higher than the second voltage level and lower than the third voltage level, the charging with the constant current is terminated.

12. The method according to any one of claims 1 to 9, further comprising the following steps: Stopping charging of the battery for a preset time between the first constant current charging and the second constant current charging; Stop charging the battery for a preset time between the second constant current charging and the third constant current charging; as well as The charging of the battery is stopped for a preset time between the third constant-current charging and the constant-voltage charging.

13. The method according to claim 1, wherein: The battery includes a lithium cobalt oxide battery cell, and the second voltage level is set to 4.4V.

14. The method according to claim 13, wherein: The first voltage level is set to 4.2V, 4.25V or 4.3V, The third voltage level is set to 4.43V or 4.45V, The first intensity is set to an intensity corresponding to a 1.5C rate, The second intensity is set to an intensity corresponding to a 1.2C rate. The third intensity is set to an intensity corresponding to a 1.0C rate, and when the third voltage level is set to 4.43V, the fourth intensity is set to an intensity corresponding to a 0.15C rate, and when the third voltage level is set to 4.45V, the fourth intensity is set to an intensity corresponding to a 0.2C rate.

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