Battery charging method, electronic device, and electric device

Abstract

Embodiments of the present application provide a battery charging method, an electronic device, and an electric device. According to the charging method provided by the present application, by high-current and low-current alternating charging and discharging cycles in a fast charging cycle process, under the condition that a charging duration slightly increases, the polarization caused by high current fast charging can be eliminated, interfacial lithium precipitation is mitigated, abnormal diving of a cell is prevented, and an interfacial SOC regional difference caused by fast charging is balanced. In addition, low-current charging can reduce a temperature rise difference of the cell, reduces regional overcharge and over-discharge, and can prolong the service life of a battery while mitigating lithium precipitation. the present application solves the problem that an existing charging mode cannot mitigate lithium precipitation of a negative electrode of a lithium battery while ensuring the fast charging performance.

Description

Battery charging method, electronic equipment and power-consuming equipment

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on July 21, 2023, with application number 202310911922.7 and title “A Battery Charging and Power-Using Device,” the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of battery control technology, and in particular to a battery charging method, electronic equipment, and electrical equipment. Background Art

[0003] At present, in order to improve users' car-using experience, the demand for fast charging of electric vehicles is constantly increasing, and the battery charging rate is constantly increasing.

[0004] Existing methods to improve fast charging include pulse charging, variable current charging, and variable voltage charging, which can increase the effective fast charging time to 10 to 30 minutes, greatly meeting users' fast charging needs.

[0005] However, the above-mentioned fast charging method will cause greater polarization in the lithium battery, and long-term use will easily lead to lithium deposition at the negative electrode of the lithium battery, affecting the battery's service life.

[0006] Application Contents

[0007] The technical problem to be solved by the present application is to provide a battery charging method, electronic equipment and electrical equipment to solve the problem that the existing charging method cannot improve the lithium plating of the battery negative electrode while ensuring fast charging performance.

[0008] In order to solve the above problems, this application is implemented through the following technical solutions:

[0009] This application proposes a battery charging method, which includes:

[0010] Charge the battery in fast charge cycle mode;

[0011] The fast charge cycle mode includes the following steps:

[0012] S111, pre-charging the battery for a first time period T1 at a first current value, wherein 0s≤T1≤5s, and the first current value is 0.1C-0.5C;

[0013] S112, after pre-charging the battery, formally charging the battery at a second current value for a second time period T2, wherein 0s<T2≤120s, and the second current value is 1C to 5C;

[0014] S113. After the battery is formally charged, pre-discharge the battery at a third current value for a third time period T3, where 3s≤T3≤10s and the third current value is 0.01C to 0.1C.

[0015] S114. After pre-discharging the battery, if the voltage of the battery is lower than the preset charge cut-off voltage, continue to execute steps S111-S113 until the voltage of the battery reaches the preset charge cut-off voltage.

[0016] Furthermore, in the charging method, before pre-charging the battery for a first time period T1 at a first current value, the method further includes the following steps:

[0017] When the number of fast charge times n of the battery charged in the fast charge cycle mode is greater than the fast charge times threshold N, the lithium plating risk of the battery is determined as follows:

[0018] If the battery does not have the risk of lithium plating, continue to charge the battery in a fast charge cycle mode;

[0019] If the battery has a risk of lithium plating, the battery is charged by switching to a slow charge cycle mode.

[0020] Furthermore, in the charging method, determining the risk of lithium plating of the battery includes:

[0021] When nN is an integer multiple of m, the lithium plating risk of the battery is judged according to the historical discharge capacity of the battery; m is the number of fast charges for two consecutive times for judging the lithium plating risk of the battery, wherein n>m.

[0022] Furthermore, in the charging method, judging the lithium plating risk of the battery according to the historical discharge capacity of the battery includes:

[0023] According to the historical discharge capacity of the battery, the discharge capacity C after the nmth cycle of fast charging is determined. n-m And the discharge capacity C after the nth round of fast charging n ;

[0024] Press (C n-m -C n ) / m, calculate and obtain the current capacity cycle change rate K1 of the battery;

[0025] According to the historical discharge capacity of the battery, when the current capacity cycle change rate K1 of the battery is greater than 0 for the first time, the capacity cycle change rate is defined as the baseline capacity cycle change rate K2;

[0026] The lithium plating risk of the battery is determined according to the current capacity cycle change rate K1 and the reference capacity cycle change rate K2.

[0027] Furthermore, in the charging method, judging the lithium plating risk of the battery according to the current capacity cycle change rate K1 and the reference capacity cycle change rate K2 includes:

[0028] When K1>x*K2, it is determined that the battery has a risk of lithium plating, wherein x=1.01-1.05.

[0029] Furthermore, before charging the battery in the fast charge cycle mode, the method further includes:

[0030] The initial value of the second current value is updated according to the current capacity cycle change rate K1 and the reference capacity cycle change rate K2, and the updating is performed in one of the following ways:

[0031] Method 1: When K1≤K2, update the second current value Ib n =Ib n-m ;

[0032] Method 2: When K2≤K1≤xK2, update the second current value Ib n =(1-K1)*Ib;

[0033] Method 3: When K1≥xK2, update the second current value Ib n =(1-K1)*Ib*γ;

[0034] Among them, Ib=α*C, K1 represents the current capacity cycle change rate, K2 represents the benchmark capacity cycle change rate, C represents the rated capacity, α represents the non-lithium precipitation coefficient, n represents the number of fast charging cycles, and γ represents the attenuation coefficient.

[0035] Furthermore, in the charging method, determining the lithium plating risk of the battery further includes:

[0036] After the battery is charged in the slow charge cycle mode, it is determined that the battery does not have the risk of lithium plating, so that the battery is charged in the fast charge cycle mode when charging is required next time.

[0037] Furthermore, charging the battery in a slow charge cycle mode includes:

[0038] Obtaining the state of charge value, attenuation coefficient, and rated capacity of the battery;

[0039] determining a slow charging current according to the state of charge value, the attenuation coefficient, and the rated capacity;

[0040] The battery is charged according to the slow charge current.

[0041] Further, determining a slow charging current according to the state of charge value, the attenuation coefficient, and the rated capacity includes:

[0042] determining an actual charge interval to which the state of charge value belongs;

[0043] Determining an actual slow charging coefficient corresponding to the actual charging interval according to a preset correspondence between the charging interval and the slow charging coefficient; wherein, in the preset correspondence, the upper limit value of each charging interval is negatively correlated with the slow charging coefficient;

[0044] The slow charging current is determined according to the product of the actual slow charging coefficient, the attenuation coefficient and the rated capacity.

[0045] Furthermore, if the battery has a risk of lithium plating, the battery is charged by switching to a slow charging cycle mode, including:

[0046] If the battery has a risk of lithium plating, the number of slow charging cycles is updated to M=M+a, and the battery is charged in the slow charging cycle mode for M consecutive times; wherein a is the increase in the number of slow charging cycles after two consecutive judgments on the risk of lithium plating of the battery.

[0047] Furthermore, in the charging method, the fast charging cycle mode further includes:

[0048] Before re-performing the step of pre-charging the battery at the first current value for the first time period T1, reducing the second current value,

[0049] Furthermore, reducing the second current value includes reducing the second current value by 2 to 5%.

[0050] Furthermore, in the charging method, before pre-charging the battery at the first current value, the method further includes:

[0051] Determine the first duration based on the state of charge value of the battery; determining the first duration includes: when the state of charge value is less than a state of charge threshold, determining that the first duration is greater than 0; when the state of charge value is greater than the state of charge threshold, determining that the first duration is 0.

[0052] Furthermore, before charging the battery in the fast charge cycle mode, it also includes: obtaining the target fast charge duration, including: obtaining the target fast charge duration; determining the first current value and the second duration based on the target fast charge duration; wherein, the first current value and the second duration are both negatively correlated with the target fast charge duration.

[0053] The present application also proposes an electronic device, comprising a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other via the communication bus; the memory is used to store a computer program; when the computer program is executed by the processor, the electronic device executes any one of the methods described above.

[0054] The present application also proposes an electrical device, including a battery and a battery management system, wherein the battery management system is used to charge the battery according to any of the above methods.

[0055] In the present application, the battery charging method provided, when charging the battery in the fast charge cycle mode, pre-charges the battery alternately at 0.1C to 0.5C for 0 to 5s, formally charges the battery at a second current value of 1C to 5C for less than or equal to 120s, and pre-discharges the battery at a third current value of 0.01C to 0.1C for 3 to 10s, until the battery voltage reaches the preset charge cut-off voltage. By performing alternating charge and discharge cycles of large and small currents during the fast charge cycle, the polarization caused by large current fast charge can be eliminated, the interface lithium plating can be improved, the abnormal cell water drop phenomenon can be prevented, and the regional difference in interface SOC caused by fast charge can be balanced while slightly increasing the charging time. In addition, low current charging can reduce the temperature rise difference of the battery cell, reduce the regional overcharge and over-discharge phenomenon, improve lithium plating, and also improve the available life of the battery, thereby solving the problem that the existing charging method cannot improve the lithium plating of the negative electrode of the lithium battery while ensuring the fast charge performance.

[0056] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following is a brief introduction to the drawings required for use in the embodiments or related technical descriptions. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0058] FIG1 is a flow chart of a battery charging method provided in an embodiment of the present application;

[0059] FIG2 is a block diagram of an electronic device provided in an embodiment of the present application. Specific embodiments

[0060] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0061] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0062] The applicant of this application has found that existing fast charging methods such as pulse charging, variable current charging and variable voltage charging can significantly increase the battery charging rate and achieve fast charging effect. However, although the above charging methods can increase the fast charging time, there is a large polarization phenomenon, which can easily cause lithium deposition on the interface, thereby affecting the cycle life of the battery.

[0063] In order to solve the above problems, the embodiment of the present application provides a battery charging method, which charges the battery in a fast charging cycle mode. As shown in FIG1 , the fast charging cycle mode includes steps S111 to S114:

[0064] Step S111 : pre-charge the battery at a first current value for a first time period T1 , wherein 0s≤T1≤5s, and the first current value is 0.1C-0.5C.

[0065] In step S111, when the fast charge cycle mode begins, the battery is first charged at a current of 0.1C to 0.5C for 0 to 5 seconds, completing a pre-charge process. This low-current charging of 0.1C to 0.5C for 0 to 5 seconds can reduce differences in cell temperature rise, mitigate regional overcharge and over-discharge, and only slightly increase charging time. This improves lithium plating and also increases the battery's usable lifespan. Where C represents the rated capacity.

[0066] Optionally, in some embodiments, T1 may be 1s, 2s, 3s, 4s, 5s, or a range between any two values.

[0067] Optionally, in some embodiments, the first current value may be 0.1C, 0.2C, 0.3C, 0.4C, 0.5C, or a range between any two of these values.

[0068] Step S112: After pre-charging the battery, formally charge the battery at a second current value for a second duration T2, wherein 0s<T2≤120s, and the second current value is 1C-5C.

[0069] In the above step S112, after the pre-charging is completed, the battery is formally charged at a current value of 1C to 5C and lasts for less than or equal to 120 seconds, completing one formal charging process.

[0070] The second duration is greater than the first duration. Optionally, in some embodiments, T2 can be 10s, 20s, 30s, 40s, 50s, 60s, 70s, 80s, 90s, 100s, 110s, 120s, or a range between any two of these values.

[0071] Optionally, in some embodiments, the second current value may be 1C, 2C, 3C, 4C, 5C, or a range between any two values.

[0072] Step S113: After the battery is formally charged, pre-discharge the battery for a third time period T3 at a third current value, wherein 3s≤T3≤10s, and the third current value is 0.01C-0.1C.

[0073] In the above step S113, after completing one formal charge, the battery is pre-discharged at a current value of 0.01C to 0.1C and lasts for 3 to 10 seconds to complete one pre-discharge process, thereby eliminating the polarization caused by high-current fast charging and improving the interface lithium plating phenomenon.

[0074] Optionally, in some embodiments, T3 may be 3s, 4s, 5s, 6s, 7s, 8s, 9s, 10s, or a range between any two values.

[0075] Optionally, in some embodiments, the third current value may be 0.01C, 0.02C, 0.03C, 0.04C, 0.05C, 0.06C, 0.07C, 0.08C, 0.09C, 0.1C, or a range between any two of these values.

[0076] Step S114: After pre-discharging the battery, if the voltage of the battery is lower than the preset charge cut-off voltage, continue to execute steps S111 to S113 until the voltage of the battery reaches the preset charge cut-off voltage.

[0077] In the above step S114, if the battery voltage is lower than the preset charging cut-off voltage, it means that the battery is not fully charged and still needs to be charged, so the step of pre-charging the battery for the first time period T1 according to the first current value is executed, that is, steps S111 to S113 are continued until the battery voltage reaches the preset charging cut-off voltage, indicating that the battery is fully charged, and then charging is stopped.

[0078] In the above-mentioned charging method provided in the embodiment of the present application, by performing alternating charge and discharge cycles of large and small currents during the fast charging cycle, the polarization caused by large-current fast charging can be eliminated, the interface lithium plating can be improved, the abnormal diving of the battery cell can be prevented, and the regional differences in the interface SOC caused by fast charging can be balanced while slightly increasing the charging time; in addition, small-current charging can reduce the temperature rise difference of the battery cell, reduce the regional overcharge and over-discharge phenomenon, improve lithium plating and also increase the battery's usable life, thereby solving the problem that the existing charging method cannot improve the lithium plating of the negative electrode of the lithium battery while ensuring fast charging performance.

[0079] In addition, the above-mentioned charging method provided in the embodiment of the present application controls the battery to charge with an optimal time and charging current value and ensures the cycle performance of the battery cell. It is simple to operate and has low optimization cost.

[0080] Optionally, in one embodiment, the charging method provided in the embodiment of the present application further includes steps S101 to S102 before charging the battery in the fast charge cycle mode.

[0081] Step S101: Obtain target fast charging duration.

[0082] In this step, the target fast charging time is the charging time for fully charging the battery selected by the user on the external charging device. When the charging gun is inserted into the charging port of the vehicle, the vehicle's battery management system communicates with the external charging device, so that the above-mentioned target charging time can be obtained.

[0083] Step S102: Determine the first current value and the second duration according to the target fast charging duration; wherein the first current value and the second duration are both negatively correlated with the target fast charging duration.

[0084] In this step, because the longer the target fast charging time is, the less electricity is required to be charged into the battery per unit time, and the shorter the target fast charging time is, the more electricity is required to be charged into the battery per unit time, so the first current value and the second time are set to be negatively correlated with the above-mentioned target fast charging time, that is, when the target fast charging time is shorter, the battery is pre-charged with a larger current value, and when the target fast charging time is longer, the battery is pre-charged with a smaller current value, which can improve the lithium plating problem as much as possible while matching the user's fast charging needs.

[0085] For example, when the target fast charging time is 10, 20, 30, and 40 minutes respectively, the first current value Ia can be set to 0.5C, 0.4C, 0.3C, and 0.2C respectively.

[0086] Optionally, in one embodiment, the fast charging cycle mode provided in the embodiment of the present application further includes step S115:

[0087] Before re-performing the step of pre-charging the battery at the first current value for the first time period T1, the second current value is reduced.

[0088] In this embodiment, the second current value of the formal charging is reduced each time a fast charging cycle is performed, so as to match the gradually increasing state of charge value, thereby more effectively mitigating the occurrence of lithium desorption risk.

[0089] Optionally, in a specific implementation, reducing the second current value specifically includes: reducing the second current value by 2-5%.

[0090] In this specific embodiment, each time a fast charging cycle is performed, the second current value of the formal charging is reduced by 2-5%.

[0091] Optionally, the reduction in the second current value can be determined based on the target fast-charge duration; wherein the reduction is negatively correlated with the target fast-charge duration. That is, when the target fast-charge duration is shorter, the second current value is reduced by a larger reduction, while when the target fast-charge duration is longer, the second current value is reduced by a smaller reduction. This can minimize the lithium plating problem while meeting the user's fast-charge requirements.

[0092] For example, when the target fast charging time is 10, 20, 30, and 40 minutes respectively, the reduction rate of the second current value can be set to 5%, 4%, 3%, and 2% respectively.

[0093] Optionally, in one embodiment, the fast charging cycle mode provided in the embodiment of the present application further includes step S103 before pre-charging the battery at the first current value:

[0094] The first duration is determined according to the state of charge value of the battery.

[0095] In this step, because the charging rate performance of the battery varies at different state of charge values, in order to balance the charging rate performance at each state of charge value, the pre-charging time can be set to match the actual charging performance of the battery each time a fast charging cycle is performed, that is, the above-mentioned first time is determined.

[0096] In practical applications, because the higher the state of charge value, the smaller the current the battery can withstand without lithium deposition, that is, the worse its rate performance, the smaller the above-mentioned second current value, the smaller the difference between the first current value and the second current value, and the less obvious the improvement in lithium deposition brought about by small current charging. Therefore, the above-mentioned first time length can be set to be negatively correlated with the state of charge value of the battery, that is, the higher the state of charge value of the battery, the shorter the above-mentioned first time length.

[0097] Optionally, in a specific embodiment, the above step S103 includes: when the state of charge value is less than the state of charge threshold, determining that the first time length is greater than 0; when the state of charge value is greater than the state of charge threshold, determining that the first time length is 0.

[0098] In the above specific implementation, the state of charge threshold is the state of charge value at which the battery is prone to lithium plating risk and requires current-limited charging. The state of charge threshold needs to be calibrated according to the actual performance of the battery, for example, it can be 80%, 85% or 90%.

[0099] In the above specific implementation manner, when the state of charge value of the battery is less than the above state of charge threshold, since the second current value of formal charging is relatively large, in order to better alleviate the polarization phenomenon, the battery needs to be pre-charged first, that is, the above first time length is set to be greater than 0; and when the state of charge value of the battery is greater than or equal to the above state of charge threshold, since the second current value of formal charging is relatively small, the polarization phenomenon caused by formal charging is weak, and there is no need to pre-charge the battery, that is, setting the above first time length to 0, which can improve the charging efficiency.

[0100] For example, when the battery state of charge is less than or equal to 80%, 0s<T2≤90s, 1s≤T1≤5s is set; and when the battery state of charge is greater than 80%, 90s<T2≤120s, T1=0s is set.

[0101] Optionally, in one embodiment, the charging method provided in the embodiment of the present application further includes steps S104 to S106 before pre-charging the battery at the first current value:

[0102] Step S104: When the number of fast charge times n of the battery charged in the fast charge cycle mode is greater than a fast charge times threshold N, determining the lithium plating risk of the battery.

[0103] In this step, a fast charge number threshold N is pre-set, and the fast charge number threshold is the number of fast charges that triggers the judgment of the lithium plating risk of the battery. The fast charge number threshold N can be calibrated according to the actual performance of the battery. For example, it can be 10 times, that is, after the number of times the battery is charged in the fast charge cycle mode in the charging method provided in the embodiment of the present application reaches 10 times, it triggers the judgment of the lithium plating risk of the battery. If the number of times the battery is charged in the fast charge cycle mode in the charging method provided in the embodiment of the present application does not reach 10 times, the step of judging the lithium plating risk of the battery is not performed.

[0104] Step S105: If the battery does not have the risk of lithium plating, continue to charge the battery in a fast charge cycle mode.

[0105] In this step, if it is determined that the battery currently does not have the risk of lithium plating, it means that the battery is in good condition and can continue to be fast charged. Therefore, the step of charging the battery in the fast charge cycle mode is continued to meet the user's fast charging needs.

[0106] Step S106: If the battery has a risk of lithium plating, switch to a slow charge cycle mode to charge the battery.

[0107] In this step, if it is determined that the battery currently has a risk of lithium plating, it means that the battery condition is poor and it can no longer be fast charged. Therefore, the battery is charged in a slow charging cycle mode to improve the battery's lithium plating problem.

[0108] In the above embodiment, the battery is charged in a fast charge cycle mode for a number of times reaching a fast charge number threshold N before the battery's lithium plating risk is judged. If there is no lithium plating risk, the battery continues to be charged in the fast charge cycle mode. Otherwise, the battery is charged in the slow charge cycle mode. This can timely alleviate the polarization of the battery and improve its lithium plating problem.

[0109] Optionally, in one embodiment, the above step S104 specifically includes:

[0110] When nN is an integer multiple of m, the lithium plating risk of the battery is judged according to the historical discharge capacity of the battery; m is the number of fast charges for two consecutive times for judging the lithium plating risk of the battery, wherein n>m.

[0111] In this embodiment, the historical discharge capacity is the capacity value output after the battery is fully charged before the start of the current charging; wherein, because the historical discharge capacity reflects the capacity retention and change trend of the battery, the lithium plating risk of the battery can be judged based on the historical discharge capacity.

[0112] In this embodiment, after the battery is charged N times in the fast charge cycle mode, as long as the battery is charged m times in the fast charge cycle mode, it is triggered to determine whether the battery has a lithium plating risk, so that the risk of lithium plating can be eliminated in time when the battery has a lithium plating risk.

[0113] Optionally, in a specific embodiment, the above m may be 10, which can minimize the number of judgments while ensuring timely judgment of the risk of lithium deposition, thereby reducing the computational load.

[0114] Optionally, in a specific implementation, the above step S104 includes steps S1041 to S1045:

[0115] S1041, determining the discharge capacity C after the nmth round of fast charging based on the historical discharge capacity of the battery n-mAnd the discharge capacity C after the nth round of fast charging n .

[0116] In this step, because the above historical discharge capacity records the capacity value output by the battery after each full charge, before executing the current charge, the discharge capacity C after the last (i.e., the last) full charge in the fast charge mode can be obtained based on the historical discharge capacity. n And the discharge capacity C after the mth time of full charging in fast charging mode n-m .

[0117] S1042, press (C n-m -C n ) / m, and calculate the current capacity cycle change rate K1 of the battery.

[0118] In this step, the difference in discharge capacity of the battery after two fast charges m times apart is divided by m to obtain the current cycle change rate of the battery capacity.

[0119] S1043 . Based on the historical discharge capacity of the battery, when the current capacity cycle change rate K1 of the battery is greater than 0 for the first time, define the capacity cycle change rate as a reference capacity cycle change rate K2 .

[0120] S1044: Determine the lithium plating risk of the battery according to the current capacity cycle change rate K1 and the reference capacity cycle change rate K2.

[0121] In this step, because the above-mentioned baseline capacity cycle change rate reflects the capacity change of the battery when charged in the fast charge cycle mode in the initial state, and the current capacity cycle change rate reflects the capacity change of the battery when charged in the fast charge cycle mode in the current state, the baseline capacity cycle change rate is compared with the current capacity cycle change rate, and it can be determined whether the current capacity cycle change rate of the battery is abnormal, that is, whether it can be determined whether there is a risk of lithium plating.

[0122] Optionally, in a specific implementation, the above step S1045 specifically includes:

[0123] When K1>x*K2, it is determined that the battery has a risk of lithium plating, wherein x=1.01-1.05.

[0124] In this specific embodiment, x is a determination coefficient, which ranges from 1.01 to 1.05 depending on the battery system and materials. When K1>x*K2, it indicates that the capacity change rate is aggravated and the battery is likely to have a serious risk of lithium deposition, and thus the battery is determined to have a risk of lithium deposition. When K1≤x*K2, it indicates that the capacity change rate is not significant and the battery lithium deposition risk is not obvious, and thus the battery can be determined to have no risk of lithium deposition.

[0125] Optionally, in one embodiment, the above step S104 further includes step S1046:

[0126] After the battery is charged in the slow charge cycle mode, it is determined that the battery does not have the risk of lithium plating, so that the battery is charged in the fast charge cycle mode when charging is required next time.

[0127] In this embodiment, because charging the battery in the slow charge cycle mode can effectively alleviate the polarization phenomenon of the battery and improve its lithium plating risk, theoretically after charging the battery in the slow charge cycle mode, the battery can continue to withstand the polarization effect brought by charging in the fast charge cycle mode, and thus it is judged that the battery does not have the risk of lithium plating, so that the battery is charged in the fast charge cycle mode when it needs to be charged next time.

[0128] Optionally, in one embodiment, charging the battery in a slow charging cycle mode includes steps S1061 to S1063:

[0129] S1061. Obtain the state of charge value, attenuation coefficient, and rated capacity of the battery.

[0130] In this step, the state of charge value refers to the state of charge value of the battery before the slow charging cycle mode, which can be directly obtained by the battery management system; the attenuation coefficient and rated capacity are fixed performance parameters of the battery and are related to the structure and material of the battery.

[0131] S1062. Determine a slow charging current according to the state of charge value, the attenuation coefficient, and the rated capacity.

[0132] In this step, because the charging current that can alleviate battery polarization and improve the risk of lithium plating is related to the battery's state of charge, attenuation coefficient and rated capacity, the matching slow charging current can be determined based on the battery's actual state of charge, attenuation coefficient and rated capacity.

[0133] S1063: Charge the battery according to the slow charging current.

[0134] In this step, the battery is charged according to the slow charging flow determined in step S1062.

[0135] In the above embodiment, when it is determined that the battery has a risk of lithium plating, a matching slow charging current is determined based on the battery's state of charge value, attenuation coefficient and rated capacity, and the battery is charged according to the slow charging current until its voltage reaches the preset charging cut-off voltage, which can better alleviate polarization and improve the lithium plating problem.

[0136] Optionally, in a specific implementation, the above step S1062 includes steps S10621 to S10623:

[0137] Step S10621: Determine the actual charge interval to which the state of charge value belongs.

[0138] In this step, the battery's state of charge is pre-divided into multiple non-overlapping charge intervals. After the battery's actual state of charge is determined, the charge interval in which the state of charge falls, i.e., the actual charge interval, can be determined based on the relationship between the state of charge value and the upper and lower limits of each charge interval.

[0139] Step S10622: Determine the actual slow charging coefficient corresponding to the actual charging interval according to a preset correspondence between the charging interval and the slow charging coefficient; wherein, in the preset correspondence, the upper limit value of each charging interval is negatively correlated with the slow charging coefficient.

[0140] In this step, a matching slow charging coefficient is set for each charge interval in advance according to the specific performance of the battery. The slow charging coefficient is greater than 0 and less than or equal to 1. Since the battery can withstand a smaller non-lithium precipitation current when the battery power is higher, the charging current needs to be gradually reduced when the power tends to saturation, that is, the upper limit value of each charge interval is negatively correlated with the slow charging coefficient.

[0141] Step S10623: Determine the slow charging current according to the product of the actual slow charging coefficient, the attenuation coefficient, and the rated capacity.

[0142] In this step, the actual slow charging coefficient is multiplied by the attenuation coefficient and the rated capacity to calculate the matching slow charging current value.

[0143] For example, the above step S1062 specifically includes: when the state of charge value is in the range of 5% to 50%, determining the slow charging current to be γC; when the state of charge value is in the range of 50% to 85%, determining the slow charging current to be 0.5γC; when the state of charge value is in the range of 85% to 97%, determining the slow charging current to be 0.2γC, where γ=C n / C1, C represents the rated capacity, γ represents the attenuation coefficient, C n Indicates the discharge capacity after the last full charge in fast charge mode. That is, if the slow charge cycle mode is triggered to charge the battery, the battery will be charged at a current of γC when the state of charge value is between 5% and 50%, at a current of 0.5γC when the battery state of charge value is between 50% and 85%, and at a current of 0.2γC when the battery state of charge value is between 85% and 97%.

[0144] In the above embodiment, when it is determined that the battery has a risk of lithium plating, the matching actual slow charging coefficient is determined based on the battery's state of charge value, and then the matching slow charging current is determined based on the actual slow charging coefficient, the attenuation coefficient and the rated capacity. The battery is charged according to the slow charging current until its voltage reaches the preset charging cut-off voltage, which can better alleviate the polarization effect and improve the lithium plating problem.

[0145] Optionally, in a specific embodiment, the above step S106 specifically includes: if the battery has a lithium plating risk, updating the number of slow charging cycles M=M+a, and charging the battery in a slow charging cycle mode for M consecutive times, wherein a is an increase in the number of slow charging cycles after two consecutive determinations of the lithium plating risk of the battery;

[0146] In this specific embodiment, the initial value of M is 0. Because the continued occurrence of lithium plating risk indicates that the health of the lithium battery continues to deteriorate, the number of slow charging cycles executed after determining that the battery has lithium plating risk gradually increases in steps of a, which can effectively address the gradually increasing lithium plating risk caused by fast charging. The above a can be 1, 2, or 3, etc.

[0147] Optionally, the value of M is set to be less than or equal to 10. Since there is less demand for slow charging in actual applications, the number of slow charging cycles is controlled within 10 weeks, that is, every 10 fast charging cycles are alternately performed with 1 slow charging cycle, and gradually continue until every 10 fast charging cycles are alternately performed with 10 slow charging cycles.

[0148] Optionally, in one embodiment, the charging method provided in the embodiment of the present application further includes step S107 before charging the battery in the fast charge cycle mode:

[0149] An initial value of the second current value is updated according to the current capacity cycle change rate K1 and the reference capacity cycle change rate K2.

[0150] In this step, before starting to charge the battery in the fast charge cycle mode, the initial formal charging current that matches the current lithium plating condition of the battery is determined based on the current capacity cycle change rate and the benchmark capacity cycle change rate of the battery, that is, the initial value of the above-mentioned second current value.

[0151] Optionally, in a specific implementation, in step S107, the update is performed in one of the following ways:

[0152] Method 1: When K1≤K2, update the second current value Ib n =Ib n-m ;

[0153] Method 2: When K2≤K1≤xK2, update the second current value Ib n=(1-K1)*Ib;

[0154] Method 3: When K1≥xK2, update the second current value Ib n =(1-K1)*Ib*γ;

[0155] Among them, Ib=α*C, K1 represents the current capacity cycle change rate, K2 represents the benchmark capacity cycle change rate, C represents the rated capacity, α represents the non-lithium precipitation coefficient, n represents the number of fast charging cycles, γ represents the attenuation coefficient, and x=1.01~1.05.

[0156] In the above specific implementation, Ib≤Imax, Imax is the maximum non-lithium deposition current of the battery cell in a specific charging range, and Imax / C is used to obtain the non-lithium deposition coefficient α.

[0157] An embodiment of the present application further provides an electrical device, including a battery and a battery management system, wherein the battery management system is used to charge the battery according to the above method.

[0158] As for the above-mentioned embodiment of the electric device, since it is basically similar to the embodiment of the battery charging method, the relevant details can be referred to the partial description of the method embodiment.

[0159] The present application is described in detail below through examples.

[0160] Example 1

[0161] (1) Preparation of positive electrode sheet

[0162] The positive electrode active material Li(Ni0.8Mn0.1Co0.1)O2(NMC811), the conductive agent acetylene black (Super P) and the binder polyvinylidene fluoride (PVDF) were mixed uniformly in a mass ratio of 94:3:3, and evenly dispersed in 1-methyl-2-pyrrolidone (NMP) to form a uniform black slurry. The mixed slurry was coated on both sides of the aluminum foil, and then baked, rolled and cut into pieces to obtain the positive electrode sheet.

[0163] (2) Preparation of negative electrode sheet

[0164] The negative electrode active material artificial graphite (AG), silicon oxide (SiO), conductive agent acetylene black (Super P) and binder SBR are mixed evenly in a mass ratio of 84.6:9.4:3:3, and evenly dispersed in deionized water to form a uniform black slurry. The mixed slurry is coated on both sides of the copper foil, baked, rolled, and cut into pieces to obtain a surface density of 7 mg / cm2 to form a negative electrode sheet.

[0165] (3) Preparation of electrolyte

[0166] Ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) are mixed uniformly in a mass ratio of 30:30:40 to obtain a mixed solvent, and then lithium salt LiPF6, or lithium salt LiPF6 and additives, are dissolved in the obtained mixed solvent and mixed uniformly to obtain an electrolyte, wherein the LiPF6 concentration in the electrolyte is 1 mol / L and the mass percentage content of LiODFB is 0.3%.

[0167] (4) Production of secondary batteries

[0168] The prepared positive electrode sheet, separator, and negative electrode sheet are stacked in order with the separator placed between the positive and negative electrode sheets. After winding, hot pressing and shaping, and tab welding, a bare cell is obtained. The bare cell is placed in an outer packaging aluminum-plastic film and baked in an oven at 85±10℃ for 24 hours. The prepared electrolyte is injected into the dried battery, allowed to stand, formed, and divided to complete the preparation of the lithium-ion soft-pack battery.

[0169] At 25°C, charge the battery according to the following steps:

[0170] (1) Charging at a constant current of Ia = 0.3C for 1s;

[0171] (2) Charging at a constant current of Ib = 1C for 10 seconds;

[0172] (3) Discharge at a constant current of 0.01C for 3 seconds;

[0173] (4) Repeat steps (1) to (3) until the battery voltage reaches the upper limit of the cut-off operating voltage, ending the cycle.

[0174] The remaining examples and comparative examples refer to Example 1, with the differences shown in Table 1;

[0175] The secondary batteries prepared in the examples and comparative examples were tested using a Xinwei battery testing system to obtain the lowest point potential of negative electrode lithium deposition for the same battery under different test conditions, and the potentials were recorded in Table 1.

[0176] The secondary batteries prepared in the examples and comparative examples were tested using a Xinwei battery testing system to obtain the battery cycle retention rates of the same batteries after 500 cycles, and the results were recorded in Table 1.

[0177] Table 1

[0178] From the test results in Table 1, it can be seen that the retention rate of comparative example 1 after 500 cycles is the best, and the negative electrode lithium deposition potential is the best, but the overall cycle period is long, which is not conducive to application; the negative electrode lithium deposition potential of comparative examples 2, 3 and 4 is low, and the retention rate after 500 cycles of the battery is poor, indicating that its cycle fast charging process performance is poor; the cycle retention rates of the other embodiments are higher than those of the comparative example, indicating that the fast charging method of alternating charge and discharge of small and large currents has greatly improved the cycle performance and the cycle retention rate is high.

[0179] An embodiment of the present application also provides an electronic device, as shown in Figure 2, including a processor 201, a communication interface 202, a memory 203 and a communication bus 204, wherein the processor 201, the communication interface 202, and the memory 203 communicate with each other through the communication bus 204.

[0180] The memory 203 is used to store computer programs.

[0181] When the processor 201 is used to execute the program stored in the memory 203, the following steps are implemented:

[0182] Charge the battery in fast charge cycle mode;

[0183] The fast charge cycle mode includes:

[0184] Pre-charging the battery for a first time period T1 at a first current value, wherein 0s≤T1≤5s, and the first current value is 0.1C-0.5C;

[0185] After pre-charging the battery, formally charging the battery for a second time period T2 at a second current value, wherein 0s<T2≤120s, and the second current value is 1C to 5C;

[0186] After the battery is formally charged, pre-discharging the battery for a third time period T3 at a third current value, wherein 3s≤T3≤10s, and the third current value is 0.01C-0.1C;

[0187] After the battery is pre-discharged, if the voltage of the battery is lower than the preset charge cut-off voltage, the step of pre-charging the battery for a first time period T1 at a first current value is continued.

[0188] The processor 201 may also implement other steps in the above-mentioned battery charging method, which will not be described in detail here.

[0189] The communication bus mentioned in the electronic device mentioned above may be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus. This communication bus can be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, only one thick line is used in the figure, but this does not mean that there is only one bus or only one type of bus.

[0190] The communication interface is used for communication between the above electronic device and other devices.

[0191] The memory may include random access memory (RAM) or non-volatile memory, such as at least one disk storage. Alternatively, the memory may be at least one storage device located away from the processor.

[0192] The above-mentioned processor can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, and discrete hardware components.

[0193] In another embodiment provided in the present application, a computer-readable storage medium is provided. The computer-readable storage medium stores instructions. When the computer-readable storage medium is run on a computer, the computer executes the battery charging method described in the above embodiment.

[0194] In another embodiment provided by the present application, a computer program product including instructions is also provided, which, when executed on a computer, enables the computer to execute the battery charging method described in the above embodiment.

[0195] In another embodiment provided in the present application, an electric device is provided, including a battery and a battery management system. The battery management system includes the electronic device as described in the above embodiment.

[0196] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When software is used for implementation, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from a website, computer, server or data center to another website, computer, server or data center via a wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) method. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrations. The available medium can be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state drive (SSD)).

[0197] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0198] Each embodiment in this specification is described in a related manner. Similar portions between the various embodiments can be referenced to each other. Each embodiment focuses on the differences from other embodiments. The embodiments of the electrical device, electronic device, computer-readable storage medium, and computer program products containing instructions thereof are generally similar to the method embodiments, so their description is relatively simple. For related portions, reference can be made to the description of the method embodiments.

[0199] The above description is only a preferred embodiment of the present application and is not intended to limit the scope of protection of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application are included in the scope of protection of the present application.

[0200] To sum up, in this embodiment, by performing alternating charge and discharge cycles of large and small currents during the fast charging cycle, the polarization caused by large-current fast charging can be eliminated, the interface lithium plating can be improved, the abnormal diving of the battery cell can be prevented, and the regional differences in interface SOC caused by fast charging can be balanced while slightly increasing the charging time; in addition, small-current charging can reduce the temperature rise difference of the battery cell, reduce the regional overcharge and over-discharge phenomenon, improve lithium plating, and also increase the battery's usable life, thereby solving the problem that the existing charging method cannot improve lithium plating at the negative electrode of the lithium battery while ensuring fast charging performance.

[0201] Although preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they become aware of the basic inventive concepts. Therefore, the claims are intended to include the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0202] The above is a detailed introduction to the battery charging method and electrical equipment provided by the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method and core ideas of the present application. At the same time, for those skilled in the art, according to the ideas of the present application, there may be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present application.

Claims

1. A method for charging a battery, wherein: include: Charge the battery in fast charge cycle mode; The fast charge cycle mode comprises the following steps: S111, pre-charging the battery for a first time period T1 at a first current value, wherein 0s≤T1≤5s, and the first current value is 0.1C-0.5C; S112, after pre-charging the battery, formally charging the battery at a second current value for a second time period T2, wherein 0s<T2≤120s, and the second current value is 1C-5C; S113, after the battery is formally charged, pre-discharging the battery for a third time period T3 at a third current value, wherein 3s≤T3≤10s, and the third current value is 0.01C-0.1C; S114. After the battery is pre-discharged, if the voltage of the battery is lower than the preset charge cut-off voltage, continue to execute steps S111-S113 until the voltage of the battery reaches the preset charge cut-off voltage.

2. The charging method according to claim 1, wherein: Before pre-charging the battery for a first time period T1 at a first current value, the method further comprises the following steps: When the number of fast charging times n of the battery charged in the fast charging cycle mode is greater than the fast charging times threshold N, the lithium plating risk of the battery is determined as follows: If the battery does not have the risk of lithium plating, continue to perform the step of charging the battery in the fast charge cycle mode; If the battery has a risk of lithium plating, the battery is charged by switching to a slow charge cycle mode.

3. The charging method according to claim 2, wherein: Determine the lithium plating risk of the battery, including: When nN is an integer multiple of m, the lithium plating risk of the battery is judged according to the historical discharge capacity of the battery; m is the number of fast charges for two consecutive times for judging the lithium plating risk of the battery, wherein n>m.

4. The charging method according to claim 3, wherein: According to the historical discharge capacity of the battery, the lithium plating risk of the battery is judged, including: According to the historical discharge capacity of the battery, the discharge capacity C after the nmth round of fast charging is determined. n-m And the discharge capacity C after the nth round of fast charging n ; Press (C n-m -C n ) / m, calculate and obtain the current capacity cycle change rate K1 of the battery; According to the historical discharge capacity of the battery, when the current capacity cycle change rate K1 of the battery is greater than 0 for the first time, the capacity cycle change rate is defined as the reference capacity cycle change rate K2; The lithium plating risk of the battery is determined according to the current capacity cycle change rate K1 and the reference capacity cycle change rate K2.

5. The charging method according to claim 4, wherein: According to the current capacity cycle change rate K1 and the reference capacity cycle change rate K2, the lithium plating risk of the battery is judged, including: When K1>x*K2, it is determined that the battery has a risk of lithium deposition, wherein x=1.01-1.

05.

6. The charging method according to claim 5, wherein: Before charging the battery in the fast charge cycle mode, the method further comprises: The initial value of the second current value is updated according to the current capacity cycle change rate K1 and the reference capacity cycle change rate K2, and the updating is performed in one of the following ways: Method 1: When K1≤K2, update the second current value Ib n =Ib n-m ; Method 2: When K2≤K1≤xK2, update the second current value Ib n =(1-K1)*Ib; Method 3: When K1≥xK2, update the second current value Ib n =(1-K1)*Ib*γ; Among them, Ib=α*C, K1 represents the current capacity cycle change rate, K2 represents the benchmark capacity cycle change rate, C represents the rated capacity, α represents the non-lithium precipitation coefficient, n represents the number of fast charging cycles, and γ represents the attenuation coefficient.

7. The charging method according to claim 3, wherein: Determining the lithium plating risk of the battery also includes: After the battery is charged in the slow charge cycle mode, the battery is determined to have no risk of lithium plating, so that the battery is charged in the fast charge cycle mode when charging is required next time.

8. The charging method according to claim 2, wherein: The battery is charged in a slow charge cycle mode, including: Obtaining the state of charge value, attenuation coefficient and rated capacity of the battery; Determining a slow charging current according to the state of charge value, the attenuation coefficient and the rated capacity; The battery is charged according to the slow charge current.

9. The charging method according to claim 8, wherein: Determining a slow charging current according to the state of charge value, the attenuation coefficient and the rated capacity includes: Determining an actual charge interval to which the state of charge value belongs; Determine the actual slow charging coefficient corresponding to the actual charging interval according to the preset corresponding relationship between the charging interval and the slow charging coefficient; wherein, in the preset corresponding relationship, the upper limit value of each charging interval is negatively correlated with the slow charging coefficient; The slow charging current is determined according to the product of the actual slow charging coefficient, the attenuation coefficient and the rated capacity.

10. The charging method according to claim 2, wherein: If the battery has a risk of lithium plating, the battery is charged by switching to a slow charging cycle mode, including: If the battery has a risk of lithium plating, the number of slow charging cycles is updated to M=M+a, and the battery is charged for M consecutive times in the slow charging cycle mode; wherein a is the increase in the number of slow charging cycles after two consecutive judgments on the risk of lithium plating of the battery.

11. The charging method according to claim 1, wherein: The fast charge cycle mode also includes: Before re-executing the step of pre-charging the battery at the first current value for the first time period T1, the second current value is reduced.

12. The charging method according to claim 11, wherein: Reducing the second current value includes: reducing the second current value by 2-5%.

13. The charging method according to claim 1, wherein: Before pre-charging the battery according to the first current value, the method further includes: Determining the first duration according to the state of charge value of the battery; determining the first duration includes: When the state of charge value is less than the state of charge threshold, determining that the first time period is greater than 0; When the state of charge value is greater than the state of charge threshold, the first time duration is determined to be 0.

14. The charging method according to claim 1, wherein: Before charging the battery in fast charge cycle mode, it also includes: Get the target fast charging duration; The first current value and the second duration are determined according to the target fast charging duration; wherein the first current value and the second duration are both negatively correlated with the target fast charging duration.

15. An electronic device, wherein: It includes a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other via the communication bus; The memory is used to store computer programs; When the computer program is executed by the processor, the electronic device performs the method according to any one of claims 1 to 14.

16. An electrical device, comprising a battery and a battery management system, wherein: The battery management system is used to charge the battery according to the method according to any one of claims 1 to 14.

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