CN116520159A - Method and electronic equipment for determining lithium-ion battery charging cut-off voltage - Google Patents

Abstract

The application discloses a method and electronic equipment for determining a charging cut-off voltage of a lithium ion battery, wherein the charging and discharging of a first period are carried out according to the maximum working voltage of the lithium ion battery so as to determine an initial charging cut-off voltage; setting the initial charge cut-off voltage as the current charge cut-off voltage, and charging and discharging the lithium ion battery for a preset number of cycles according to the current charge cut-off voltage; acquiring current voltage data and current capacity data in the charging process of the last period; constructing a current differential capacity curve according to the current voltage data and the current capacity data; determining the current charge cut-off voltage from the voltages corresponding to the characteristic peaks of the current differential capacity curve, and returning to the step of charging and discharging the lithium ion battery for a preset number of cycles according to the current charge cut-off voltage until the current capacity data meet preset conditions. By determining different charging cut-off voltages for the lithium ion battery, the battery is charged in a healthy voltage range, and the service life of the battery is prolonged.

Description

Method and electronic equipment for determining lithium-ion battery charging cut-off voltage

technical field

The application belongs to the technical field of lithium-ion batteries, and in particular relates to a method and electronic equipment for determining the charging cut-off voltage of a lithium-ion battery.

Background technique

With the gradual expansion of the application of lithium-ion batteries in the field of new energy vehicles, the research on lithium-ion batteries has also received extensive attention.

At present, during the charging process of lithium-ion batteries, due to the failure to design a reasonable charging cut-off voltage, the crystal structure of the electrode material of the battery changes, which leads to a sharp decline in the capacity of the battery and reduces the service life of the battery.

Contents of the invention

Embodiments of the present application provide a method and electronic equipment for determining the cut-off voltage of a lithium-ion battery, thereby enabling the battery to be charged within a healthy voltage range and prolonging the service life of the battery.

Other features and advantages of the present application will become apparent from the following detailed description, or in part, be learned by practice of the present application.

According to the first aspect of the embodiments of the present application, a method for determining the charging cut-off voltage of a lithium-ion battery is provided, the method comprising:

According to the maximum operating voltage of the lithium ion battery, the lithium ion battery is charged and discharged for the first cycle to determine the initial charge cut-off voltage;

Setting the initial charge cut-off voltage as the current charge cut-off voltage, and charging and discharging the lithium-ion battery for a preset number of cycles according to the current charge cut-off voltage;

Obtain the current voltage data and current capacity data during the charging process of the last cycle;

Constructing a current differential capacity curve according to the current voltage data and the current capacity data;

Determine the current charge cut-off voltage from the voltage corresponding to the characteristic peak of the current differential capacity curve, and return to the step of charging and discharging the lithium-ion battery for a preset number of cycles according to the current charge cut-off voltage until the The current capacity data satisfies the preset condition.

In some embodiments of the present application, based on the foregoing scheme, the lithium-ion battery is charged and discharged for the first cycle according to the maximum working voltage of the lithium-ion battery to determine the initial charge cut-off voltage, including:

Carry out the charging of the first cycle to described lithium-ion battery;

When the voltage of the lithium-ion battery reaches the maximum working voltage, stop charging;

Acquiring initial voltage data and initial capacity data during the charging process of the first cycle;

constructing an initial differential capacity curve according to the initial voltage data and the initial capacity data;

The initial charging cut-off voltage is determined from the voltage corresponding to the characteristic peak of the initial differential capacity curve.

In some embodiments of the present application, based on the foregoing solution, the method is applied to a vehicle, the vehicle includes a battery management system and a battery of the same type as the lithium-ion battery, and the method further includes:

storing the initial charging cut-off voltage and the current charging cut-off voltage in the battery management system, so that the battery management system controls charging of the battery according to the initial charging cut-off voltage and the current charging cut-off voltage.

In some embodiments of the present application, based on the foregoing scheme, the charging of the first cycle of the lithium-ion battery includes:

Using multiple preset temperatures and multiple preset charge cut-off currents to charge the lithium-ion battery for the first cycle;

Correspondingly, the determining the initial charging cut-off voltage from the voltage corresponding to the characteristic peak of the initial differential capacity curve includes:

determining multiple initial charge cut-off voltages from voltages corresponding to characteristic peaks of multiple initial differential capacity curves;

The determining the current charging cut-off voltage from the voltage corresponding to the characteristic peak of the current differential capacity curve includes:

The multiple current charging cut-off voltages are determined from the voltages corresponding to the characteristic peaks of the multiple current differential capacity curves.

In some embodiments of the present application, based on the foregoing solution, storing the initial charging cut-off voltage and the current charging cut-off voltage to the battery management system includes:

The preset temperature, the preset charging cut-off current, the initial charging cut-off voltage and the current charging cut-off voltage are correspondingly stored in the battery management system.

In some embodiments of the present application, based on the foregoing solution, the preset condition includes: a ratio of the current capacity data to the initial capacity data is less than or equal to 0.8.

In some embodiments of the present application, based on the foregoing solution, the current voltage data includes a plurality of voltage data, the current capacity data includes a plurality of capacity data, the voltage data corresponds to the capacity data one by one, the Constructing a current differential capacity curve according to the current voltage data and the current capacity data, including:

Determine the voltage difference between two adjacent voltage data;

determining a capacity difference between two capacity data corresponding to the two voltage data;

The ratio of the voltage difference to the capacity difference is taken as the ordinate value of the current differential capacity curve, and the larger value of the two voltage data is taken as the abscissa value of the current differential capacity curve.

In some embodiments of the present application, based on the foregoing solution, the determining the current charging cut-off voltage from the voltage corresponding to the characteristic peak of the current differential capacity curve includes:

determining the voltage at the H2-H3 phase transition position from the voltage corresponding to the characteristic peak of the current differential capacity curve;

The voltage at the H2-H3 phase transition position is determined as the current charging cut-off voltage.

In some embodiments of the present application, based on the aforementioned solution, the determining the voltage at the H2-H3 phase transition position from the voltage corresponding to the characteristic peak of the current differential capacity curve includes:

The maximum voltage among the voltages corresponding to the characteristic peak of the current differential capacity curve is determined as the voltage at the H2-H3 phase transition position.

According to a second aspect of the embodiments of the present application, an electronic device is provided, including a memory and a processor, the memory stores a computer program, and the processor implements the steps of the above method when executing the computer program.

In the present application, the initial charging cut-off voltage is determined by charging and discharging the lithium-ion battery for the first cycle according to the maximum working voltage of the lithium-ion battery; the initial charging cut-off voltage is set as the current charging cut-off voltage, And according to the current charging cut-off voltage, charge and discharge the lithium-ion battery for a preset number of cycles; obtain the current voltage data and current capacity data in the charging process of the last cycle; according to the current voltage data and the current capacity constructing the current differential capacity curve based on the data; determining the current charging cut-off voltage from the voltage corresponding to the characteristic peak of the current differential capacity curve, and returning the preset number of cycles of the lithium-ion battery according to the current charging cut-off voltage In the step of charging and discharging, until the current capacity data meets the preset conditions, different charging cut-off voltages are determined for the life cycle of the lithium-ion battery, so that the battery can be charged within a healthy voltage range, prolonging the service life of the battery.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application.

Description of drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and together with the description serve to explain the principles of the application. Apparently, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creative efforts. In the attached picture:

Fig. 1 is a schematic flow chart of the method for determining lithium-ion battery charging cut-off voltage in an embodiment;

Fig. 2 is a schematic diagram of the differential capacity curve in an embodiment;

Fig. 3 is the schematic diagram of differential capacity curve in another embodiment;

Fig. 4 is a schematic flow chart of step 101 in an embodiment;

Fig. 5 is a schematic flow chart of a method for determining the charging cut-off voltage of a lithium-ion battery in another embodiment;

Fig. 6 is an internal structure diagram of an electronic device in one embodiment.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the application with reference to the drawings in the embodiments of the application. Apparently, the described embodiments are only some of the embodiments of the application, not all of them. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of this application.

Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided in order to give a thorough understanding of the embodiments of the application. However, those skilled in the art will appreciate that the technical solutions of the present application may be practiced without one or more of the specific details, or other methods, components, devices, steps, etc. may be employed. In other instances, well-known methods, apparatus, implementations, or operations have not been shown or described in detail to avoid obscuring aspects of the application.

The flow charts shown in the drawings are only exemplary illustrations, and do not necessarily include all contents and operations/steps, nor must they be performed in the order described. For example, some operations/steps can be decomposed, and some operations/steps can be combined or partly combined, so the actual order of execution may be changed according to the actual situation.

It should be noted that the terms "first" and "second" in the specification and claims of the present application and the above drawings are used to distinguish similar objects, but not necessarily to describe a specific sequence or sequence. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the application described herein can be practiced in sequences other than those illustrated or described.

Fig. 1 is a schematic flow chart of the method for determining the charging cut-off voltage of a lithium-ion battery in an embodiment, as shown in Fig. 1 , a method for determining the charging cut-off voltage of a lithium-ion battery is provided, and the method may include the following steps:

Step 101, charge and discharge the lithium ion battery for the first cycle according to the maximum working voltage of the lithium ion battery, so as to determine the initial charge cut-off voltage.

Among them, the lithium-ion battery is the test battery. By testing the lithium-ion battery, the charging cut-off voltage of the entire life cycle of the lithium-ion battery is determined. When the vehicle is installed with this type of lithium-ion battery, the charging cut-off voltage determined above can be The voltage controls the charging of the lithium-ion battery, so that the lithium-ion battery in the vehicle is always charged within a healthy voltage range, prolonging the service life of the battery.

Specifically, testers can charge the lithium-ion battery for the first cycle until the voltage of the lithium-ion battery reaches the maximum operating voltage, then stop charging, let it stand still, and then discharge. During the charging process, the initial voltage data and the initial capacity data are continuously obtained, and the initial charging cut-off voltage is determined according to the initial voltage data and the initial capacity data.

It should be understood that the steps in this embodiment can be implemented manually by testers, or can be automatically implemented through program settings, and there is no limitation on the subject of execution in this embodiment.

Step 102, setting the initial charging cut-off voltage as the current charging cut-off voltage, and charging and discharging the lithium-ion battery for a preset number of cycles according to the current charging cut-off voltage.

Wherein, the preset number may be 50, 100, 200 or other numbers, which is not limited in this embodiment. For ease of description, the preset period is 100 as an example for illustration below.

It can be understood that after obtaining the initial charging cut-off voltage, the lithium-ion battery can be charged and discharged for 100 cycles, specifically, the lithium-ion battery can be charged until the voltage reaches the current charging cut-off voltage, and then the lithium-ion battery is left standing. Lithium-ion batteries are discharged and cycled 100 times.

Step 103, acquiring current voltage data and current capacity data during the charging process of the last cycle.

Specifically, when the lithium-ion battery is charged and discharged for the 100th cycle, the voltage and capacity during the 100th cycle of charging are collected and used as current voltage data and current capacity data, respectively.

Step 104, constructing a current differential capacity curve according to the current voltage data and the current capacity data.

Since charging is a continuous process, multiple voltage data and multiple capacity data can be obtained during the 100th week of charging, and the voltage data and capacity data at the same time are corresponding, so the current voltage data can include multiple voltages data, the current capacity data may include a plurality of capacity data, and the voltage data corresponds to the capacity data one by one.

In this case, the voltage difference between two adjacent voltage data can be determined; the capacity difference between two capacity data corresponding to the two voltage data can be determined; the ratio of the voltage difference to the capacity difference As the ordinate value of the current differential capacity curve, the larger value of the two voltage data is used as the abscissa value of the current differential capacity curve.

Specifically, the voltage data of the n+1th data point can be subtracted from the voltage data of the nth data point to obtain a dV data, and the electric quantity data of the n+1th data point can be subtracted from the electric quantity of the nth data point Data, a dQ data is obtained, and all the data are processed in turn to obtain a series of dV and dQ data. Then divide dV by the corresponding dQ to get another data dV/dQ. Take all the dV/dQ as the ordinate, and take the voltage corresponding to dV/dQ, the capacitance or SOC corresponding to dV/dQ as the abscissa, you can get the differential capacity curve of capacitance and voltage, and use it as the current differential capacity curve, according to This curve can analyze the phase transition of the positive and negative electrodes of the lithium-ion battery during charging and discharging.

It should be noted that when the abscissa of the current differential capacity curve is the voltage corresponding to dV/dQ, testers can quickly determine the current cut-off voltage through the curve, improving the efficiency of determining the current cut-off voltage.

Step 105, determine the current charging cut-off voltage from the voltage corresponding to the characteristic peak of the current differential capacity curve, and return to the step of charging and discharging the lithium-ion battery for a preset number of cycles according to the current charging cut-off voltage until the current capacity data meets the preset condition.

It should be noted that dV/dQ is the capacity contained in the material within the unit voltage range. Both positive and negative materials have a voltage platform, and the negative electrode capacity of the voltage platform is higher, which means that within a small voltage fluctuation range There is a lot of capacity, so it is a characteristic peak on the differential capacity curve. The characteristic peak refers to the maximum point or minimum point in the differential capacity curve. The peak that appears on the differential capacity curve represents the phase transition of the material, and the movement of each peak and peak shape changes represent different decay mechanisms. Since the reaction potentials of different materials are different, the position and height of the characteristic peaks in the differential capacity curve will also be different.

In an example, when the abscissa of the differential capacity curve is the voltage corresponding to dV/dQ, the tester can directly find the voltage corresponding to the characteristic peak from the current differential capacity curve, and determine the current charging cut-off voltage therefrom.

In a specific implementation, the tester can also determine the voltage at the H2-H3 phase transition position from the voltage corresponding to the characteristic peak of the current differential capacity curve; determine the voltage at the H2-H3 phase transition position as the current charging cut-off voltage.

It should be understood that in the charging and discharging process of lithium-ion batteries, in order to obtain higher energy density, more lithium ions are extracted from the positive electrode material, accompanied by the intercalation and extraction of lithium ions in the electrode material, within the cycle range, The capacity will drop sharply, which is a capacity fading failure.

The root cause of battery capacity decay failure is the failure of materials, and it is also closely related to objective factors such as battery manufacturing process and battery use environment. The positive electrode material is charged and delithiated, the voltage end, and the phase transition from H2 to H3 will cause the lattice to shrink in the c direction, resulting in volume change and local stress. After the H2-H3 phase transition, the H3 phase is formed, and the irreversible phase transition will lead to microcracks and structural deformation, and after the microcracks form new crystal planes, side reactions will occur with the electrolyte.

Therefore, the voltage at the H2-H3 phase transition position can be used as the current charging cut-off voltage, so that the failure of the electrode material can be effectively avoided during the charging process, thereby achieving the purpose of protecting the lithium-ion battery.

Among them, the tester can determine the maximum voltage among the voltages corresponding to the characteristic peak of the current differential capacity curve as the voltage at the H2-H3 phase transition position.

Figure 2 is a schematic diagram of the differential capacity curve in one embodiment, and Figure 3 is a schematic diagram of the differential capacity curve in another embodiment, wherein Figure 3 is obtained after charging according to the initial charging cut-off voltage and the current charging cut-off voltage of this embodiment Differential Capacity Curve. The position and shape of the characteristic peaks in Figure 2 change more, but the position and shape of the characteristic peaks in Figure 3 change little, and the loss of the reversible capacity of the battery is less.

It should be noted that, after determining the current charge cut-off voltage V100 of the 100th cycle, the tester uses the current charge cut-off voltage V100 to continue charging and discharging the lithium-ion battery for the next 100 cycles, and obtains the current charge cut-off voltage of the 200th cycle. Voltage V200, the tester uses the current charge cut-off voltage V200 to continue charging and discharging the lithium-ion battery for the next 100 cycles, and obtains the current charge cut-off voltage V300 of the 300th cycle... and so on until the current capacity data is consistent with the lithium-ion battery. The ratio of the initial capacity of the ion battery is less than or equal to 0.8.

After obtaining all the cut-off voltages of the battery life cycle, the initial cut-off voltage and all current cut-off voltages can be used as the cut-off voltages of batteries of the same type as lithium-ion batteries, and the battery can be charged according to the cut-off voltage , which can ensure that the battery is charged within a healthy voltage range.

In this embodiment, the lithium-ion battery is charged and discharged for the first cycle according to the maximum working voltage of the lithium-ion battery to determine the initial charge cut-off voltage; the initial charge cut-off voltage is set as the current charge cut-off voltage, and according to the current charge cut-off voltage Charge and discharge the lithium-ion battery for a preset number of cycles; obtain the current voltage data and current capacity data during the charging process of the last cycle; construct the current differential capacity curve according to the current voltage data and current capacity data; from the characteristics of the current differential capacity curve Determine the current charging cut-off voltage from the voltage corresponding to the peak, and return to the step of charging and discharging the lithium-ion battery for a preset number of cycles according to the current charging cut-off voltage until the current capacity data meets the preset conditions, which is determined for the life cycle of the lithium-ion battery Different charging cut-off voltages enable the battery to be charged within a healthy voltage range, prolonging the service life of the battery.

Fig. 4 is a schematic flow chart of step 101 in an embodiment, as shown in Fig. 4, according to the maximum working voltage of lithium-ion battery, lithium-ion battery is charged and discharged for the first cycle, to determine the initial charging cut-off voltage may include the following steps :

Step 401, charging the lithium-ion battery for the first cycle;

Step 402, when the voltage of the lithium-ion battery reaches the maximum working voltage, stop charging;

Step 403, acquiring initial voltage data and initial capacity data during the charging process of the first cycle;

Step 404, constructing an initial differential capacity curve according to the initial voltage data and the initial capacity data;

Step 405, determining the initial charging cut-off voltage from the voltage corresponding to the characteristic peak of the initial differential capacity curve.

In a specific implementation, the tester can use the specified temperature and current to charge the lithium-ion battery for the first cycle. For example, a common temperature and a common current are used for charging, or multiple temperatures and multiple currents are used for charging.

It should be understood that if the vehicle is still in the plugged-in state after being fully charged, the lithium-ion battery will be repeatedly charged several times, or charged with a very small trickle current, so that the battery is always fully charged or exceeds the remaining power (State OfCharge, SOC) window usage state, reducing the service life of the battery. Different operating conditions at the charging end (such as different temperatures and different rates) will result in different cut-off dynamic voltages. Under the same cut-off voltage, the higher the temperature and the smaller the rate, the more capacity will be charged. For the problem of SOC exceeding the upper limit, the battery can be charged at different temperatures and currents to achieve calibration differentiation.

In one example, the tester can charge the lithium-ion battery for the first cycle using multiple preset temperatures and multiple preset charge cut-off currents. Correspondingly, determining the initial charging cut-off voltage from the voltage corresponding to the characteristic peak of the initial differential capacity curve includes: determining the multiple initial charging cut-off voltages from the voltages corresponding to the characteristic peaks of the initial differential capacity curve. Determining the current cut-off charging voltage from the voltages corresponding to the characteristic peaks of the current differential capacity curve includes: determining a plurality of current charging cut-off voltages from the voltages corresponding to the characteristic peaks of the current differential capacity curve.

That is to say, when the tester uses multiple preset temperatures and multiple preset charge cut-off currents to charge the lithium-ion battery for the first cycle, each preset temperature and preset charge cut-off current can get a a corresponding initial charge cut-off voltage, and a plurality of corresponding current charge cut-off voltages.

When this method is applied to a vehicle, and the vehicle includes a battery management system and a battery of the same type as a lithium-ion battery, the tester stores the initial charge cut-off voltage and the current charge cut-off voltage in the battery management system, so that the battery management system voltage and the current charge cutoff voltage control battery charging.

And when each preset temperature and preset charging cut-off current can obtain a corresponding initial charging cut-off voltage and multiple corresponding current charging cut-off voltages, the tester can set the preset temperature, preset charging cut-off current, initial charging cut-off voltage The cut-off voltage and the current charging cut-off voltage are correspondingly stored in the battery management system.

In one example, after stopping charging, the tester can also leave the Li-ion battery at rest and discharge the Li-ion battery.

In an example, the specific implementation method of constructing the initial differential capacity curve according to the initial voltage data and initial capacity data may be the same as that of the current differential curve, assuming that the initial voltage data includes multiple voltage data, and the initial capacity data includes multiple capacity data , the tester can determine the voltage difference between two adjacent voltage data; determine the capacity difference between the two capacity data corresponding to the two voltage data; use the ratio of the voltage difference to the capacity difference as the initial The ordinate value of the differential capacity curve, the larger value of the two voltage data is taken as the abscissa value of the initial differential capacity curve.

Specifically, the voltage data of the n+1th data point can be subtracted from the voltage data of the nth data point to obtain a dV data, and the electric quantity data of the n+1th data point can be subtracted from the electric quantity of the nth data point Data, a dQ data is obtained, and all the initial data are processed in turn to obtain a series of dV and dQ data. Then divide dV by the corresponding dQ to get another data dV/dQ. Taking all dV/dQ as the ordinate, taking the voltage corresponding to dV/dQ, the capacitance or SOC corresponding to dV/dQ as the abscissa, you can get the differential capacity curve of capacitance and voltage, and use it as the initial differential capacity curve.

In an example, determining the initial charging cut-off voltage from the voltage corresponding to the characteristic peak of the initial differential capacity curve can be determined in the same manner as the current charging cut-off voltage, that is, H2 can be determined from the voltage corresponding to the characteristic peak of the initial differential capacity curve -The voltage at the H3 phase transition position; the voltage at the H2-H3 phase transition position is determined as the initial charging cut-off voltage; where the voltage at the H2-H3 phase transition position is usually the maximum of the voltages corresponding to the characteristic peaks of the initial differential capacity curve Voltage.

In an example, the preset condition includes: a ratio of the current capacity data to the initial capacity data is less than or equal to 0.8.

It should be understood that, usually for a new battery, the ratio of the current capacity data to the initial capacity data is generally greater than 100%. With the use of the battery, the battery continues to age and the ratio gradually decreases. It is clearly stipulated in IEEE Standard 1188-1996 , when the capacity of the power battery drops to 80%, that is, when the ratio of the current capacity data to the initial capacity data is less than or equal to 0.8, the battery should be replaced. By setting this preset condition, the charging cut-off voltage of the battery's full life cycle can be obtained.

This embodiment realizes the determination of the initial charging cut-off voltage, improves the accuracy of the charging cut-off voltage of the lithium-ion battery, realizes the charging management of the battery life cycle, further protects the battery and improves the battery life, and helps to improve the battery life of the vehicle. level of safety.

FIG. 5 is a schematic flow chart of a method for determining the cut-off voltage of a lithium-ion battery in another embodiment. As shown in FIG. 5 , the method for determining the cut-off voltage of a lithium-ion battery may include the following steps:

Step 501, charging the lithium-ion battery for the first cycle, and stopping charging when the voltage of the lithium-ion battery reaches the maximum working voltage;

Step 502, acquiring initial voltage data and initial capacity data during the charging process of the first cycle;

Step 503, constructing an initial differential capacity curve according to the initial voltage data and initial capacity data;

Step 504, determine the first voltage at the H2-H3 phase transition position from the voltage corresponding to the characteristic peak of the initial differential capacity curve, and determine the first voltage as the initial charging cut-off voltage;

Step 505, setting the initial charging cut-off voltage as the current charging cut-off voltage, and charging and discharging the lithium-ion battery for a preset number of cycles according to the current charging cut-off voltage;

Step 506, obtaining the current voltage data and current capacity data during the charging process of the last cycle;

Step 507, constructing a current differential capacity curve according to the current voltage data and the current capacity data;

Step 508, determine the second voltage of the H2-H3 phase transition position from the voltage corresponding to the characteristic peak of the current differential capacity curve, determine the second voltage as the current cut-off voltage of charging, and return to the lithium-ion battery according to the current cut-off voltage of charging The step of charging and discharging for a preset number of cycles until the ratio of the current capacity data to the initial capacity data is less than or equal to 0.8.

It should be understood that although the steps in the flow charts involved in the above embodiments are shown sequentially according to the arrows, these steps are not necessarily executed sequentially in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and these steps can be executed in other orders. Moreover, at least some of the steps in the flow charts involved in the above-mentioned embodiments may include multiple steps or stages, and these steps or stages are not necessarily executed at the same time, but may be performed at different times For execution, the execution order of these steps or stages is not necessarily performed sequentially, but may be executed in turn or alternately with other steps or at least a part of steps or stages in other steps.

Based on the same inventive concept, the embodiment of the present application also provides an electronic device. FIG. 6 is an internal structure diagram of an electronic device in one embodiment. As shown in FIG. At least one computer program (program code) running on 602, when the processor 602 executes the computer program, implements the method for determining the charging cut-off voltage of the lithium-ion battery as described above.

Wherein, in FIG. 6, the bus architecture (represented by bus 600), bus 600 may include any number of interconnected buses and bridges, and bus 600 will include one or more processors represented by processor 602 and memory 604. The various circuits of the memory are linked together. The bus 600 may also link together various other circuits, such as peripherals, voltage regulators, and power management circuits, etc., which are well known in the art and thus will not be further described herein. The bus interface 605 provides an interface between the bus 600 and the receiver 601 and the transmitter 603 . Receiver 601 and transmitter 603 may be the same element, a transceiver, providing means for communicating with various other devices over a transmission medium. Processor 602 is responsible for managing bus 600 and general processing, while memory 604 may be used to store data used by processor 602 in performing operations.

Those skilled in the art can understand that the structure shown in Figure 6 is only a block diagram of a part of the structure related to the solution of this application, and does not constitute a limitation on the electronic equipment to which the solution of this application is applied. The specific electronic equipment can be More or fewer components than shown in the figures may be included, or some components may be combined, or have a different arrangement of components.

The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Other examples and implementations are within the scope and spirit of the application and appended claims. For example, due to the nature of software, functions described above can be implemented using software executed by a processor, hardware, firmware, hardwiring, or a combination of any of these. In addition, each functional unit may be integrated into one processing unit, each unit may exist separately physically, or two or more units may be integrated into one unit.

In the several embodiments provided in this application, it should be understood that the disclosed technical content can be realized in other ways. Wherein, the device embodiments described above are only illustrative. For example, the division of the units may be a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components may be combined or may be Integrate into another system, or some features may be ignored, or not implemented. In another point, the mutual coupling or direct coupling or communication connection shown or discussed may be through some interfaces, and the indirect coupling or communication connection of units or modules may be in electrical or other forms.

The above description is only an embodiment of the present application, and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included within the scope of the claims of the present application.

Claims (10)

1. A method of determining a charge cutoff voltage of a lithium ion battery, the method comprising:

charging and discharging the lithium ion battery for a first period according to the maximum working voltage of the lithium ion battery so as to determine an initial charge cut-off voltage;

setting the initial charge cut-off voltage as a current charge cut-off voltage, and charging and discharging the lithium ion battery for a preset number of cycles according to the current charge cut-off voltage;

acquiring current voltage data and current capacity data in the charging process of the last period;

constructing a current differential capacity curve according to the current voltage data and the current capacity data;

determining a current charge cut-off voltage from voltages corresponding to characteristic peaks of the current differential capacity curve, and returning to the step of charging and discharging the lithium ion battery for a preset number of cycles according to the current charge cut-off voltage until the current capacity data meets preset conditions.

2. The method of claim 1, wherein the charging and discharging the lithium ion battery for a first period based on a maximum operating voltage of the lithium ion battery to determine an initial charge cutoff voltage comprises:

charging the lithium ion battery for a first period;

stopping charging when the voltage of the lithium ion battery reaches the maximum working voltage;

acquiring initial voltage data and initial capacity data in the first period charging process;

constructing an initial differential capacity curve according to the initial voltage data and the initial capacity data;

and determining the initial charge cut-off voltage from the voltages corresponding to the characteristic peaks of the initial differential capacity curve.

3. The method of claim 2, applied to a vehicle comprising a battery management system and a battery of the same type as the lithium ion battery, the method further comprising:

and storing the initial charge cut-off voltage and the current charge cut-off voltage to the battery management system so that the battery management system controls the battery to charge according to the initial charge cut-off voltage and the current charge cut-off voltage.

4. The method of claim 3, wherein said charging the lithium-ion battery for a first period comprises:

charging the lithium ion battery for a first period by utilizing a plurality of preset temperatures and a plurality of preset charging cut-off currents;

accordingly, the determining the initial charge cutoff voltage from the voltages corresponding to the characteristic peaks of the initial differential capacity curve includes:

determining a plurality of initial charge cut-off voltages from voltages corresponding to characteristic peaks of a plurality of initial differential capacity curves;

the determining the current charging cut-off voltage from the voltages corresponding to the characteristic peaks of the current differential capacity curve comprises the following steps:

and determining a plurality of current charging cut-off voltages from voltages corresponding to characteristic peaks of the current differential capacity curves.

5. The method of claim 4, wherein the storing the initial charge cutoff voltage and the current charge cutoff voltage to the battery management system comprises:

and correspondingly storing the preset temperature, the preset charge cut-off current, the initial charge cut-off voltage and the current charge cut-off voltage to the battery management system.

6. The method according to claim 2, wherein the preset conditions include: the ratio of the current capacity data to the initial capacity data is less than or equal to 0.8.

7. The method of claim 1, wherein the current voltage data comprises a plurality of voltage data, the current capacity data comprises a plurality of capacity data, the voltage data corresponds to the capacity data one-to-one, and the constructing a current differential capacity curve from the current voltage data and the current capacity data comprises:

determining a voltage difference between two adjacent voltage data;

determining a capacity difference value between two capacity data corresponding to the two voltage data;

and taking the ratio of the voltage difference value and the capacity difference value as an ordinate value of the current differential capacity curve, and taking the larger value of the two voltage data as an abscissa value of the current differential capacity curve.

8. The method of claim 1, wherein determining the current charge cutoff voltage from the voltages corresponding to the characteristic peaks of the current differential capacity curve comprises:

determining the voltage of the H2-H3 phase change position from the voltages corresponding to the characteristic peaks of the current differential capacity curve;

and determining the voltage of the H2-H3 phase change position as the current charge cut-off voltage.

9. The method of claim 8, wherein determining the voltage at the H2-H3 phase change location from the voltages corresponding to the characteristic peaks of the current differential capacity curve comprises:

and determining the maximum voltage in the voltages corresponding to the characteristic peaks of the current differential capacity curve as the voltage of the H2-H3 phase change position.

10. An electronic device comprising a memory storing a computer program and a processor implementing the steps of the method of any one of claims 1 to 9 when the computer program is executed.