CN106785132A - Charging method and device - Google Patents

Abstract

The embodiment of the present invention provides a charging method and device. The charging method provided by the embodiment of the present invention includes: N charging stages, each charging stage includes M charging processes, N is an integer greater than or equal to 2, and M is an integer greater than or equal to 1; each charging process includes: charging the battery at a constant current until the battery reaches a cut-off voltage; and charging the battery at a constant voltage until the battery reaches a cut-off current; wherein the cut-off current used in each charging process in the i-th charging stage is less than the cut-off current used in each charging process in the i+1-th charging stage; the value range of i is [1, N-1]. In the technical solution of the present invention, by adjusting the cut-off current, the polarization phenomenon of the battery is reduced and the battery life is extended.

Description

Charging method and device

technical field

The invention relates to the technical field of batteries, in particular to a charging method and device.

Background technique

With the continuous development and progress of society, more and more products use electric energy as a power source, such as electronic equipment, electric vehicles, etc. Advances in technology have diversified the functions of products and increased power consumption. Since the rated capacity of the battery is fixed, the frequency of charging the battery will also increase accordingly. With the limitation of the production process level of the battery cell, the number of cycles that the battery can be used is limited, and the increase in the frequency of charging directly affects the service life of the product where the battery is located.

The method of charging the battery in the prior art usually adopts the method of constant current and constant voltage charging, uses a constant current to charge the battery until the voltage of the battery reaches the cut-off voltage, and uses a constant voltage to continue charging the battery until the voltage of the battery reaches the cut-off current until.

Using the method in the prior art to charge the battery, as the number of charging increases, the polarization of the battery gradually becomes serious, resulting in a faster rise in voltage when charging with a constant current, and thus a shorter duration of constant current charging, and When charging with a constant voltage, the current drop rate will slow down, and the constant voltage charging time will become longer, which will increase the structural instability of the battery cell material at a higher voltage, which will lead to serious attenuation of the battery capacity and shorten the battery life. lifespan.

Contents of the invention

The embodiments of the present invention provide a charging method and device, which can reduce the polarization phenomenon of the battery and prolong the service life of the battery by adjusting the magnitude of the cut-off current.

An embodiment of the present invention provides a charging method, including: N charging stages, each charging stage includes M charging processes, N is an integer greater than or equal to 2, and M is an integer greater than or equal to 1;

Each charging process includes:

Charging the battery at a constant current until the battery reaches a cutoff voltage; and,

Charge the battery with a constant voltage until the battery reaches the cut-off current;

Wherein, the cutoff current used in each charging process in the i-th charging stage is smaller than the cut-off current used in each charging process in the i+1th charging stage; the value range of i is [1, N-1].

According to the above aspects and any possible implementation, an implementation is further provided,

The values of M corresponding to each charging stage are equal; or,

The values of M corresponding to each charging stage are different; or,

The value of M corresponding to each charging stage is partially equal.

According to the above aspects and any possible implementation, an implementation is further provided,

Also includes:

The sum of the preset current adjustment value and the cut-off current used in each charging process in the i-th charging stage is calculated as the cut-off current used in each charging process in the i+1th charging stage.

According to the above aspects and any possible implementation, an implementation is further provided,

The same current adjustment value is used each time the cutoff current is calculated; or,

The same and different current adjustment values are used each time the cut-off current is calculated; or

The current adjustment value used is partly the same each time the cutoff current is calculated.

According to the above aspects and any possible implementation, an implementation is further provided,

The current adjustment value is equal to 0.025C.

The embodiment of the present invention also provides a charging device, which is applied to N charging stages, and each charging stage includes M charging processes, N is an integer greater than or equal to 2, and M is an integer greater than or equal to 1;

The devices include:

The first charging module is used to charge the battery with a constant current until the battery reaches the cut-off voltage during each charging process; and,

The second charging module is used to charge the battery with a constant voltage during each charging process until the battery reaches the cut-off current and stops;

Wherein, the cutoff current used in each charging process in the i-th charging stage is smaller than the cut-off current used in each charging process in the i+1th charging stage; the value range of i is [1, N-1].

According to the above aspects and any possible implementation, an implementation is further provided,

The values of M corresponding to each charging stage are equal; or,

The values of M corresponding to each charging stage are different; or,

The value of M corresponding to each charging stage is partially equal.

According to the above aspects and any possible implementation, an implementation is further provided,

Also includes:

The calculation module is used to calculate the sum of the preset current adjustment value and the cut-off current used in each charging process in the i-th charging stage as the cut-off current used in each charging process in the i+1th charging stage.

According to the above aspects and any possible implementation, an implementation is further provided,

The same current adjustment value is used each time the cutoff current is calculated; or,

The same and different current adjustment values are used each time the cut-off current is calculated; or

The current adjustment value used is partly the same each time the cutoff current is calculated.

According to the above aspects and any possible implementation, an implementation is further provided,

The current adjustment value is equal to 0.025C.

In the charging method and device provided by the embodiments of the present invention, by adjusting the cut-off current of the battery when the battery is charged with a constant voltage at different charging stages, the cut-off current of the battery is adjusted to be higher and lower as the number of charging times increases. The larger the value, the shorter the time required for the current to drop to the cut-off current when charging at a constant voltage, thus shortening the time for charging the battery, and at the same time reducing the polarization of the battery, thereby prolonging the life of the battery and solving the problem In the prior art, the polarization phenomenon of the battery caused by repeated charging of the battery by a fixed charging method is gradually serious, so that the time for constant current charging becomes shorter, and the time for constant voltage charging becomes longer. The structural instability of the cell material increases under voltage, which in turn leads to serious attenuation of the capacity of the battery and shortens the life of the battery.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained according to these drawings without any creative effort.

FIG. 1 is a flow chart of Embodiment 1 of the charging method provided by the embodiment of the present invention;

Fig. 2 is a relation diagram between charging time and charging current in the prior art;

FIG. 3 is a graph showing the relationship between charging time and charging current in an embodiment of a charging method provided by an embodiment of the present invention;

FIG. 4 is a flow chart of Embodiment 2 of the charging method provided by the embodiment of the present invention;

Fig. 5 is a comparison chart about the number of cycles and capacity retention in Embodiment 1;

Figure 6 is a comparison chart of the number of cycles and capacity retention in Embodiment 2;

Fig. 7 is a schematic structural diagram of Embodiment 1 of the charging device provided by the embodiment of the present invention;

FIG. 8 is a schematic structural diagram of Embodiment 2 of the charging device provided by the embodiment of the present invention.

detailed description

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

It should be understood that the term "and/or" used herein is only an association relationship describing associated objects, which means that there may be three relationships, for example, A and/or B, which may mean that A exists alone, and A and B exist simultaneously. B, there are three situations of B alone. In addition, the character "/" in this article generally indicates that the contextual objects are an "or" relationship.

Embodiment one

Fig. 1 is a flow chart of the first embodiment of the charging method provided by the embodiment of the present invention. As shown in Fig. 1, the charging method of this embodiment may specifically include the following steps:

101. Charge the battery with a constant current until the battery reaches the cut-off voltage and stop.

In the embodiment of the present invention, different positive electrode materials and negative electrode materials are used to make battery cells. Due to the different properties of the battery cell materials themselves, the performance of the battery is jointly determined. As the battery is charged and discharged many times, the chemical changes in the cells inside the battery will gradually accumulate. Therefore, in the case that the performance of the battery is difficult to change, in order to reduce the probability that the polarization phenomenon of the battery in the battery will damage the stability of the battery material structure, the number of cycles of the battery is increased by adjusting the cut-off current.

It should be noted that, in the embodiment of the present invention, the number of cycles refers to one full charge and one full discharge of the battery. In the embodiment of the present invention, the charging process adopts a constant current and constant voltage charging method to charge the battery or adopts a step-charge charging method to charge the battery.

As the number of battery cycles increases, the materials inside the cell, such as the positive electrode material lithium cobaltate, etc., will release more lithium ions, which will make the structure of the cell material unstable. Therefore, in the charging method in the embodiment of the present invention, the process of charging the battery is divided into N charging stages, each charging stage includes M charging processes, N is an integer greater than or equal to 2, and M is greater than or equal to 1 an integer of .

For example, the process of charging the battery is divided into 5 charging stages, each charging stage includes 50 charging processes, then the first charging stage is 1 to 50 charging processes, and the second charging stage is 51 to 100 times charging process, and so on.

Due to the different components of the cell materials of different types of batteries, the rated capacity will also be different, and the performance of the corresponding batteries will be different, that is, the chemical changes that occur during the charging process of the battery will also be different. Or, batteries of the same model may have different chemical changes during charging. Therefore, in a specific implementation process, the values of M corresponding to each charging stage are equal; or, the values of M corresponding to each charging stage are not equal; or, the values of M corresponding to each charging stage are partially equal.

For example, the charging process of the battery is divided into 4 charging stages, and the number of charging processes in each charging stage is equal, including 100 charging processes, then the first charging stage is 1 to 100 charging processes, and the second A charging stage is 101 to 200 charging processes, and so on.

For another example, the process of charging the battery is divided into 4 charging stages, and the value of the charging process in each charging stage is not equal, then the first charging stage is 1 to 100 charging processes, and the second charging stage is 101 ~250 times of charging process, the third charging stage is 251~400 times of charging process, and the fourth charging stage is 401~600 times of charging process.

For another example, the process of charging the battery is divided into 4 charging stages, and the value of the charging process in each charging stage is partially equal, then the first charging stage is 1 to 100 times of charging, and the second charging stage is 101 to 100 times. 200 times of charging, the third charging stage is 201~400 times of charging, and the fourth charging stage is 401~600 times of charging.

Therefore, use a constant current to charge the battery, so that the voltage of the battery increases gradually with the charging time, and stops charging the battery when the battery reaches the cut-off voltage.

102. Charge the battery with a constant voltage until the battery reaches the cut-off current and stop.

Fig. 2 is a diagram showing the relationship between charging time and charging current in the prior art, and Fig. 3 is a diagram showing the relationship between charging time and charging current in the embodiment of the charging method provided by the embodiment of the present invention, as shown in Fig. 2 and Fig. 3 , as the battery As the number of cycles increases, the polarization of the battery gradually becomes stronger, making the voltage rise faster during constant current charging, so the time for the voltage to rise to the cut-off voltage becomes shorter, and the corresponding power stored in the battery will decrease. . When using a constant voltage to continue charging the battery, in order to weaken the polarization phenomenon, so that the battery can reach the rated capacity, the charging time of the battery will gradually become longer when the battery reaches the cut-off current, and the battery will be in a high voltage state for a long time. , the battery is more prone to capacity loss. Therefore, in the embodiment of the present invention, the charging time is shortened by adjusting the cut-off current of each charging stage.

Wherein, the cutoff current used in each charging process in the i-th charging stage is smaller than the cut-off current used in each charging process in the i+1th charging stage; the value range of i is [1, N-1].

It can be understood that as the number of charging processes gradually increases, the cut-off current of the battery gradually increases.

For example, the process of charging the battery is divided into 4 charging stages, and the number of charging processes in each charging stage is equal to 100 charging processes. Then the cut-off current of the first charging stage is 0.001C, the cut-off current of the second charging stage is 0.003C, the cut-off current of the third charging stage is 0.01C, and the cut-off current of the fourth charging stage is 0.01C.

In a specific implementation process, the cut-off current used in each charging process in each charging stage can be preset or calculated in real time.

In a specific implementation process, the battery charged by using the charging method in the embodiment of the present invention can be applied to terminals, wearable devices, electric tools, mobile power supplies, drones, electric vehicles, and electric vehicles.

It should be noted that the terminals involved in the embodiments of the present invention may include but not limited to personal computers (Personal Computer, PC), personal digital assistants (Personal Digital Assistant, PDA), wireless handheld devices, tablet computers (Tablet Computer), Mobile phones, MP3 players, MP4 players, etc.

It should be noted that the wearable devices involved in the embodiments of the present invention may include, but are not limited to, smart bracelets, smart watches, smart glasses, bluetooth earphones, and the like.

It should be noted that the electric vehicles involved in the embodiments of the present invention may include but not limited to electric bicycles, electric tricycles, electric balance vehicles and the like.

In the charging method provided by the embodiment of the present invention, by adjusting the cut-off current of the battery when the battery is charged with a constant voltage at different charging stages, the cut-off current of the battery is adjusted to be larger and larger as the charging times increase. , so that when the constant voltage is charged, the time required for the current to decrease to the cut-off current is shortened, so the time for charging the battery is shortened, and at the same time, the polarization of the battery can be reduced, thereby prolonging the life of the battery and solving the existing problem In the technology, the polarization phenomenon of the battery caused by repeated charging of the battery with a fixed charging method is gradually serious, which makes the time of constant current charging shorter and the time of constant voltage charging longer, and the battery is charged at a higher voltage. The structural instability of the battery material increases, which in turn leads to serious attenuation of the battery capacity and shortens the life of the battery.

Embodiment two

Fig. 4 is a flow chart of the second embodiment of the charging method provided by the embodiment of the present invention. As shown in Fig. 4, the charging method of this embodiment may specifically include the following steps:

201. Charge the battery with a constant current until the battery reaches the cut-off voltage and stop.

For the specific process of step 201, refer to the description of step 101 in the first embodiment above. The principle and implementation process are the same in the embodiment of the present invention, and will not be repeated here.

202. Calculate the sum of the preset current adjustment value and the cut-off current used in each charging process in the i-th charging stage as the cut-off current used in each charging process in the i+1th charging stage.

It can be understood that the current adjustment value is a value used to adjust the cut-off current. In the embodiment of the present invention, the cut-off current in the first charging stage does not need to be adjusted. The cut-off current in the second charging stage adjusts the cut-off current in the third charging stage according to the cut-off current in the second charging stage, and so on.

The specific adjustment method is, cut-off current in the second charging stage=cut-off current in the first charging stage+current adjustment value, cut-off current in the third charging stage=cut-off current in the second charging stage + current adjustment value, and so on.

In a specific implementation process, the current adjustment value used for each calculation of the cut-off current is the same; or, the current adjustment value used for each calculation of the cut-off current is the same and different; or the current adjustment value used for each calculation of the cut-off current is different; The current adjustment value of the part is the same.

For example, the process of charging the battery is divided into 4 charging stages, and the current adjustment value used in each calculation of the cut-off current is the same, which is 0.01C. The cut-off current of the first charging stage is 0.001C, and the second The cut-off current of the first charging stage is 0.011C, the cut-off current of the third charging stage is 0.021C, and the cut-off current of the fourth charging stage is 0.031C.

For another example, the process of charging the battery is divided into 5 charging stages, and the current adjustment values used in each calculation of the cut-off current are different, which are 0.01C, 0.02C, 0.03C, 0.04C, and the first The cut-off current of the charging stage is 0.001C, then the cut-off current of the second charging stage is 0.011C, the cut-off current of the third charging stage is 0.031C, the cut-off current of the fourth charging stage is 0.061C, and the cut-off current of the fifth charging stage is 0.011C. The cut-off current of the stage is 0.101C.

For another example, the process of charging the battery is divided into 5 charging stages, and the current adjustment values used in each calculation of the cut-off current are partly the same, which are 0.01C, 0.02C, 0.01C, 0.02C, and the first The cut-off current of the charging stage is 0.001C, then the cut-off current of the second charging stage is 0.011C, the cut-off current of the third charging stage is 0.031C, the cut-off current of the fourth charging stage is 0.041C, and the cut-off current of the fifth charging stage is 0.011C. The cut-off current of the stage is 0.061C.

In a specific implementation process, in order to achieve a better adjustment effect, the current adjustment value may be equal to 0.025C.

203. Charge the battery with a constant voltage until the battery reaches the cut-off current and stop.

For the specific process of step 203, refer to the description of step 102 in the first embodiment above. The principle and implementation process are the same in the embodiment of the present invention, and will not be repeated here.

The charging method provided by the embodiment of the present invention calculates the magnitude of the cut-off current of the battery in each charging stage by adjusting the constant voltage charging of the battery in different charging stages, and then performs constant voltage charging according to the corresponding magnitude of the cut-off current, As the number of charging times increases, the cut-off current of the battery is adjusted to be larger and larger, so that the time required for the current to drop to the cut-off current becomes shorter when charging at a constant voltage, thus shortening the time for charging the battery and at the same time being able to Reduce the polarization phenomenon of the battery, thereby prolonging the life of the battery, and solve the problem that the polarization phenomenon of the battery caused by charging the battery multiple times with a fixed charging method in the prior art is gradually serious, making the time for constant current charging Shorter, the time for constant voltage charging will be longer, and the structural instability of the battery cell material will increase at a higher voltage, which will lead to serious attenuation of the battery capacity and shorten the battery life.

In order to make the purpose, technical solution and technical effect of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the embodiments given in the specification are only for explaining the present invention, not for limiting the present invention, and the present invention is not limited to the embodiments given in the specification.

Implementation plan one

Choose 4 batteries of the same type, numbered No. 1, No. 2, No. 3 and No. 4. Batteries 1 to 4 are charged with the same data during the constant current charging phase. In the constant voltage charging phase, the cut-off currents of batteries No. 1 and No. 2 are set to 0.025C, and the cut-off currents of batteries No. 3 and No. 4 are set to 0.05C. Perform 800 cycles on the 4 batteries respectively, and record the remaining capacity of each battery in each cycle.

Table 1 is a comparison table about the cut-off current and remaining capacity in Embodiment 1, and Figure 5 is a comparison chart about the number of cycles and capacity retention in Embodiment 1, as shown in Figure 5 and Table 1, as the cycle progresses, Especially when the number of cycles is getting larger and larger, the remaining capacity of the battery with a larger cut-off current is greater than that of a battery with a smaller cut-off current. It can be seen from the data in Table 1 that the charging method in the embodiment of the present invention is used to charge the battery, which can reduce the polarization phenomenon, maintain the remaining capacity of the battery, and further improve the service life of the battery.

Capacity retention (%)=(remaining capacity of n cycles/initial capacity)×100%.

Table 1

Implementation plan two

Choose 4 batteries of the same type, numbered No. 1, No. 2, No. 3 and No. 4. Batteries 1 to 4 are charged with the same data during the constant current charging phase. In the constant voltage charging stage, the cut-off current of the No. 1 battery and the No. 2 battery is set to 0.025C, and 800 cycles are performed on the two batteries respectively. In the 1-100 cycle, the cut-off current of the No. 3 battery and the No. 4 battery is set to 0.025C, and in the 101-200 cycle, the cut-off current of the No. In the second cycle, the cut-off current of the No. 3 battery and the No. 4 battery is set to 0.075C, and in the 301~400 cycles, the cut-off current of the No. 3 battery and the No. 4 battery is set to 0.1C, and so on. Record the remaining capacity of each battery for each cycle.

Table 2 is a comparison table about the cut-off current and remaining capacity in Embodiment 2, and Figure 6 is a comparison diagram about the number of cycles and capacity retention in Embodiment 2, as shown in Figure 6 and Table 2, as the cycle progresses, Especially when the number of cycles is getting larger and larger, the remaining capacity of the battery with a larger cut-off current is greater than that of a battery with a smaller cut-off current. From the data in Table 2, it can be seen that using the charging method in the embodiment of the present invention to charge the battery can reduce the polarization phenomenon, maintain the remaining capacity of the battery, and further improve the service life of the battery.

Table 2

Embodiment Three

Fig. 7 is a schematic structural diagram of the first embodiment of the charging device provided by the embodiment of the present invention. As shown in Fig. 5, the charging device according to the embodiment of the present invention is applied to N charging stages, each charging stage includes M charging processes, and N is an integer greater than or equal to 2, and M is an integer greater than or equal to 1, including the first charging module 11 and the second charging module 12 .

The first charging module 11 is configured to charge the battery with a constant current during each charging process until the battery reaches a cut-off voltage and stops.

The second charging module 12 is used to charge the battery with a constant voltage during each charging process until the battery reaches the cut-off current and stops;

Wherein, the cutoff current used in each charging process in the i-th charging stage is smaller than the cut-off current used in each charging process in the i+1th charging stage; the value range of i is [1, N-1].

In a specific implementation process, the values of M corresponding to each charging stage are equal; or,

The values of M corresponding to each charging stage are different; or,

The value of M corresponding to each charging stage is partially equal.

The device of this embodiment can be used to implement the technical solution of the method embodiment shown in FIG. 1 , and its implementation principle and technical effect are similar, and will not be repeated here.

Embodiment four

FIG. 8 is a schematic structural diagram of Embodiment 2 of the charging device provided by the embodiment of the present invention. As shown in FIG.

The calculation module 13 is used to calculate the sum of the preset current adjustment value and the cut-off current used in each charging process in the i-th charging stage as the cut-off current used in each charging process in the i+1th charging stage.

In a specific implementation process, the current adjustment value used for each calculation of the cut-off current is the same; or, the current adjustment value used for each calculation of the cut-off current is the same and different; or, the current adjustment value used for each calculation of the cut-off current is different; The current trim values used are partly the same.

In a specific implementation, the current adjustment value is equal to 0.025C.

The device of this embodiment can be used to implement the technical solution of the method embodiment shown in FIG. 2 , and its implementation principle and technical effect are similar, and will not be repeated here.

Those skilled in the art can clearly understand that for the convenience and brevity of the description, the specific working process of the above-described system, device and unit can refer to the corresponding process in the foregoing method embodiment, which will not be repeated here.

The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or may be distributed to multiple network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

The device embodiments described above are only illustrative, and the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place , or can also be distributed to at least two network elements. Part or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. It can be understood and implemented by those skilled in the art without any creative efforts.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: It is still possible to modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the various embodiments of the present invention. scope.

Claims (10)

1. A method of charging, the method comprising: n charging stages, wherein each charging stage comprises M charging processes, N is an integer greater than or equal to 2, and M is an integer greater than or equal to 1;

each charging process includes:

charging the battery with a constant current until the battery reaches a cut-off voltage; and the number of the first and second groups,

charging the battery at a constant voltage until the battery reaches a cutoff current;

wherein, the cut-off current used in each charging process in the ith charging stage is less than the cut-off current used in each charging process in the (i + 1) th charging stage; the value range of i is [1, N-1 ].

2. The method of claim 1,

the values of M corresponding to each charging stage are equal; or,

the values of M corresponding to each charging stage are unequal; or,

the value of M corresponding to each charging stage is partially equal.

3. The method of claim 1 or 2, further comprising:

and calculating the sum of a preset current adjustment value and the cutoff current used in each charging process in the ith charging stage to serve as the cutoff current used in each charging process in the (i + 1) th charging stage.

4. The method of claim 3,

the current adjustment values used in each calculation of the cutoff current are the same; or,

the current adjustment values used in the process of calculating the cut-off current each time are the same and different; or,

the current adjustment value used each time the off-current is calculated is partially the same.

5. The method of claim 4, wherein the current adjustment value is equal to 0.025C.

6. A charging device is characterized in that the charging device is applied to N charging stages, each charging stage comprises M charging processes, N is an integer greater than or equal to 2, and M is an integer greater than or equal to 1;

the device comprises:

the first charging module is used for charging the battery with constant current in each charging process until the battery reaches a cut-off voltage;

the second charging module is used for charging the battery at a constant voltage in each charging process until the battery reaches a cut-off current;

wherein, the cut-off current used in each charging process in the ith charging stage is less than the cut-off current used in each charging process in the (i + 1) th charging stage; the value range of i is [1, N-1 ].

7. The apparatus of claim 6,

the values of M corresponding to each charging stage are equal; or,

the values of M corresponding to each charging stage are unequal; or,

the value of M corresponding to each charging stage is partially equal.

8. The apparatus of claim 6 or 7, further comprising:

and the calculation module is used for calculating the sum of a preset current adjustment value and the cutoff current used in each charging process in the ith charging stage to serve as the cutoff current used in each charging process in the (i + 1) th charging stage.

9. The apparatus of claim 8,

the current adjustment values used in each calculation of the cutoff current are the same; or,

the current adjustment values used in the process of calculating the cut-off current each time are the same and different; or,

the current adjustment value used each time the off-current is calculated is partially the same.

10. The apparatus of claim 9, wherein the current adjustment value is equal to 0.025C.