Charging and power consuming device for a battery

Abstract

The embodiment of the present application provides a battery charging method and a power utilization device, wherein the charging method provided by the embodiment of the present application can eliminate the polarization caused by large-current fast charging, improve the interface lithium precipitation, prevent the abnormal diving phenomenon of the battery cell, and balance the regional difference of the interface SOC caused by the fast charging by alternately performing the large-current and small-current charging and discharging cycles in the fast charging cycle, with a small increase in the charging time. In addition, the small-current charging can reduce the temperature rise difference of the battery cell, reduce the regional overcharging and overdischarging phenomenon, improve the lithium precipitation, and also improve the available life of the battery, thereby solving the problem that the existing charging method cannot improve the lithium battery negative electrode lithium precipitation under the premise of ensuring the fast charging performance.

Description

Technical Field

[0001] This invention relates to the field of battery control technology, and in particular to a battery charging method and electrical equipment. Background Technology

[0002] Currently, in order to improve the user experience, the demand for fast charging of electric vehicles is constantly increasing, and the charging rate of batteries is constantly increasing.

[0003] Existing methods for improving fast charging include pulse charging, variable current charging, and variable voltage charging, which can extend the effective fast charging time to 10-30 minutes, greatly meeting users' fast charging needs.

[0004] However, the aforementioned fast charging methods can cause significant polarization in lithium batteries, which can lead to lithium plating on the negative electrode with prolonged use, posing a risk to battery use. While the degree of lithium plating can be mitigated through process optimizations such as material selection and coating, these optimization methods also have drawbacks, including complex processes and the potential to affect fast charging performance. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a battery charging method and electrical equipment to solve the problem that existing charging methods cannot improve lithium plating on the negative electrode of the battery while ensuring fast charging performance.

[0006] To solve the above problems, the present invention is achieved through the following technical solution:

[0007] This invention proposes a method for charging a battery, comprising:

[0008] Charge the battery using the fast charging cycle mode;

[0009] The fast charging cycle mode includes the following steps:

[0010] S111. The battery is pre-charged for a first duration T1 according to the first current value, wherein 0s≤T1≤5s, and the first current value is 0.1C~0.5C;

[0011] S112. After pre-charging the battery, perform formal charging of the battery for a second duration T2 according to the second current value, wherein 0s<T2≤120s, and the second current value is 1C~5C.

[0012] S113. After the battery is formally charged, the battery is pre-discharged for a third duration T3 according to the third current value, wherein 3s≤T3≤10s, and the third current value is 0.01C~0.1C.

[0013] S114. After pre-discharging the battery, if the battery voltage is lower than the preset charging cutoff voltage, continue to execute steps S111-S113 until the battery voltage reaches the preset charging cutoff voltage.

[0014] Furthermore, in the charging method, before pre-charging the battery at the first current value for a first duration T1, the method further includes the following steps:

[0015] If the number of fast charging cycles (n) for the battery exceeds the fast charging cycle threshold (N), determine the lithium plating risk of the battery:

[0016] If the battery does not have a risk of lithium plating, continue with the step of charging the battery in fast charging cycle mode;

[0017] If the battery is at risk of lithium plating, switch to slow charge cycle mode to charge the battery.

[0018] Furthermore, in the charging method, determining the risk of lithium plating in the battery includes:

[0019] When nN is an integer multiple of m, the lithium plating risk of the battery is determined based on the battery's historical discharge capacity; m is the number of fast charges between two consecutive determinations of the battery's lithium plating risk, where n > m.

[0020] Furthermore, in the charging method, determining the lithium plating risk of the battery based on its historical discharge capacity includes:

[0021] Based on the battery's historical discharge capacity, determine the discharge capacity C after the nmth fast charge cycle. n-m And the discharge capacity C after the nth fast charge cycle n ;

[0022] Press (C) n-m -C n ) / m, calculate the current capacity cycle change rate K1 of the battery;

[0023] Based on the battery's historical discharge capacity, when the battery's current capacity cycle change rate K1 is greater than 0 for the first time, the capacity cycle change rate is defined as the reference capacity cycle change rate K2.

[0024] The lithium plating risk of the battery is determined based on the current capacity cycle change rate K1 and the baseline capacity cycle change rate K2.

[0025] Furthermore, in the charging method, determining the lithium plating risk of the battery based on the current capacity cycle change rate K1 and the reference capacity cycle change rate K2 includes:

[0026] If K1 > x*K2, the battery is deemed to have a risk of lithium plating, where x = 1.01 to 1.05.

[0027] Furthermore, in the charging method, determining the risk of lithium plating in the battery further includes:

[0028] After charging the battery in slow charging cycle mode, the battery is determined to have no risk of lithium plating, so that the battery is charged in fast charging cycle mode the next time it needs to be charged.

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

[0030] Before re-executing the step of pre-charging the battery at the first current value for a first duration T1, the second current value is reduced.

[0031] The second current value is reduced by 2% to 5%.

[0032] Furthermore, before charging the battery in the fast charging cycle mode, the charging method further includes:

[0033] The initial value of the second current value is updated based on the current capacity cycle change rate K1 and the reference capacity cycle change rate K2, according to one of the following methods:

[0034] Method 1: When K1≤K2, update the second current value Ib n =Ib n-m ;

[0035] Method 2: When K2≤K1≤xK2, update the second current value Ib. n = (1-K1)*Ib;

[0036] Method 3: When K1≥xK2, update the second current value Ib. n = (1-K1)*Ib*Υ;

[0037] Where Ib=α*C, K1 represents the current capacity cycle change rate, K2 represents the reference capacity cycle change rate, C represents the rated capacity, α represents the non-lithium plating coefficient, n represents the number of fast charging cycles, Υ represents the attenuation coefficient, and x=1.01~1.05.

[0038] Furthermore, before pre-charging the battery according to the first current value, the charging method further includes:

[0039] Based on the state of charge (SOC) value of the battery, the first duration is determined; and the target fast charging duration is obtained: wherein determining the first duration includes: determining the first duration to be greater than 0 when the SOC value is less than the SOC threshold; and determining the first duration to be 0 when the SOC value is greater than the SOC threshold; obtaining the target fast charging duration includes: determining the first current value and the second duration based on the target fast charging duration; wherein the first current value and the second duration are both negatively correlated with the target fast charging duration.

[0040] Furthermore, in the charging method, charging the battery in a slow charging cycle mode includes:

[0041] Obtain the state of charge (SOC), degradation coefficient, and rated capacity of the battery;

[0042] The slow charging current is determined based on the state of charge value, the attenuation coefficient, and the rated capacity;

[0043] The battery is charged according to the slow charging current.

[0044] Furthermore, in the charging method, determining the slow charging current based on the state of charge value, the attenuation coefficient, and the rated capacity includes:

[0045] Determine the actual charge range to which the state of charge value belongs;

[0046] Based on a preset correspondence between the charge range and the slow charging coefficient, the actual slow charging coefficient corresponding to the actual charge range is determined; wherein, in the preset correspondence, the upper limit of each charge range is negatively correlated with the slow charging coefficient.

[0047] The slow charging current is determined by multiplying the actual slow charging coefficient, the attenuation coefficient, and the rated capacity.

[0048] The present invention 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 the method described above.

[0049] Compared with the prior art, the embodiments of the present invention have the following advantages:

[0050] In this embodiment of the invention, the battery charging method, when charging the battery in fast charging cycle mode, alternately pre-charges the battery at 0.1C to 0.5C for 0 to 5 seconds, performs formal charging at a second current value of 1C to 5C for less than or equal to 120 seconds, and pre-discharges the battery at a third current value of 0.01C to 0.1C for 3 to 10 seconds, until the battery voltage reaches the preset charging cutoff voltage. By alternating large and small current charging and discharging cycles during fast charging, polarization caused by high-current fast charging can be eliminated with a slight increase in charging time, improving interface lithium plating, preventing abnormal cell voltage drops, and balancing regional differences in interface SOC caused by fast charging. In addition, low-current charging can reduce cell temperature rise differences, reduce regional overcharging and over-discharging phenomena, improve lithium plating, and also increase the battery's usable life. Therefore, it solves the problem that existing charging methods cannot improve lithium plating on the negative electrode of lithium batteries while ensuring fast charging performance.

[0051] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0052] Figure 1 This is a flowchart of a battery charging method provided in an embodiment of the present invention;

[0053] Figure 2 A block diagram of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0054] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0055] The applicant of this invention has discovered that existing fast charging methods such as pulse charging, variable current charging, and variable voltage charging can significantly improve the charging rate of batteries and achieve fast charging effects. However, although the above charging methods can improve the fast charging time, they have a large polarization phenomenon, which can easily cause lithium plating at the interface, thereby affecting the cycle life of the battery.

[0056] To address the aforementioned problems, this invention provides a battery charging method that charges the battery using a fast charging cycle mode, such as... Figure 1 As shown, the above fast charging cycle mode includes steps S111 to S114:

[0057] Step S111: Precharge the battery for a first duration T1 according to the first current value, wherein 0s≤T1≤5s, and the first current value is 0.1C~0.5C.

[0058] In step S111 above, when starting the fast charging cycle mode, the battery is first charged with a current value of 0.1C to 0.5C for 0 to 5 seconds to complete one pre-charge process. This low-current charging of 0.1C to 0.5C for 0 to 5 seconds reduces cell temperature rise differences, reduces regional overcharging and over-discharging phenomena, and only slightly increases charging time. It also improves lithium plating and extends the battery's usable lifespan. Here, C represents the rated capacity.

[0059] Optionally, in some implementations, T1 can be 1s, 2s, 3s, 4s, 5s, or a range between any two of these values.

[0060] Optionally, in some implementations, the first current value can be 0.1C, 0.2C, 0.3C, 0.4C, 0.5C, or a range between any two of these values.

[0061] Step S112: After pre-charging the battery, perform formal charging of the battery for a second duration T2 according to the second current value, wherein 0s < T2 ≤ 120s, and the second current value is 1C to 5C.

[0062] In step S112 above, after pre-charging is completed, the battery is formally charged at a current value of 1C to 5C and the charge is maintained for less than or equal to 120 seconds to complete one formal charging process.

[0063] Wherein, the second duration is greater than the first duration. Optionally, in some implementations, T2 can be 10s, 20s, 30s, 40s, 50s, 60s, 70s, 80s, 90s, 100s, 110s, 120s or a range between any two of these values.

[0064] Optionally, in some implementations, the second current value can be 1C, 2C, 3C, 4C, 5C, or a range between any two of these values.

[0065] Step S113: After the battery is formally charged, the battery is pre-discharged for a third duration T3 according to the third current value, wherein 3s≤T3≤10s, and the third current value is 0.01C~0.1C.

[0066] In step S113 above, after completing one formal charge, the battery is pre-discharged at a current value of 0.01C to 0.1C for 3 to 10 seconds to complete one pre-discharge process, thereby eliminating polarization caused by high-current fast charging and improving the interface lithium plating phenomenon.

[0067] Optionally, in some implementations, T3 can be 3s, 4s, 5s, 6s, 7s, 8s, 9s, 10s, or a range between any two of these values.

[0068] Optionally, in some embodiments, the third current value can 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.

[0069] Step S114: After pre-discharging the battery, if the battery voltage is lower than the preset charging cutoff voltage, continue to execute steps S111-S113 until the battery voltage reaches the preset charging cutoff voltage.

[0070] In step S114 above, if the battery voltage is lower than the preset charging cutoff voltage, it means that the battery is not fully charged and still needs to be charged. Therefore, the step of pre-charging the battery for a first duration T1 according to the first current value is executed, that is, the steps S111 to S113 are continued until the battery voltage reaches the preset charging cutoff voltage, indicating that the battery is fully charged, and then charging is stopped.

[0071] In the charging method provided by the embodiments of the present invention, by performing alternating charge and discharge cycles of large and small currents during the fast charging cycle, polarization caused by high-current fast charging can be eliminated, interface lithium plating can be improved, abnormal cell temperature drops can be prevented, and regional differences in interface SOC caused by fast charging can be balanced. In addition, low-current charging can reduce cell temperature rise differences, reduce regional overcharging and over-discharging phenomena, improve lithium plating, and also improve the battery's usable life. Therefore, it solves the problem that existing charging methods cannot improve lithium plating on the negative electrode of lithium batteries while ensuring fast charging performance.

[0072] In addition, the charging method provided in the embodiments of the present invention controls the battery to be charged 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.

[0073] Optionally, in one embodiment, the charging method provided by the present invention further includes steps S101 to S102 before charging the battery in a fast charging cycle mode.

[0074] Step S101: Obtain the target fast charging time.

[0075] In this step, the target fast charging time is the charging time for the battery to be fully charged selected by the user on the external charging device. When the charging gun is inserted into the vehicle's charging port, the vehicle's battery management system communicates with the external charging device, thus obtaining the aforementioned target charging time.

[0076] Step S102: Determine the first current value and the second duration based on the target fast charging duration; wherein the first current value and the second duration are both negatively correlated with the target fast charging duration.

[0077] In this step, since a longer target fast charging time requires less battery charge per unit time, and a shorter target fast charging time requires more battery charge per unit time, the first current value and the second duration are negatively correlated with the target fast charging time. That is, when the target fast charging time is shorter, a larger current value is used to pre-charge the battery, and when the target fast charging time is longer, a smaller current value is used to pre-charge the battery. This can improve the lithium plating problem as much as possible while matching the user's fast charging needs.

[0078] For example, when the target fast charging time is 10, 20, 30, and 40 minutes, the first current value Ia can be set to 0.5C, 0.4C, 0.3C, and 0.2C respectively.

[0079] Optionally, in one embodiment, the fast charging cycle mode provided by the present invention further includes step S115:

[0080] Before re-executing the step of pre-charging the battery at the first current value for a first duration T1, the second current value is reduced.

[0081] In this implementation, the second current value of the formal charging is reduced once each fast charging cycle is performed, thereby matching the gradually increasing state of charge value and more effectively mitigating the occurrence of lithium desorption risks.

[0082] Optionally, in one specific embodiment, reducing the second current value specifically includes reducing the second current value by an amount of 2 to 5%.

[0083] In this specific implementation, the second current value for formal charging is reduced by 2 to 5% for each fast charging cycle.

[0084] Optionally, the reduction in the second current value can be determined based on the target fast charging duration; wherein the reduction is negatively correlated with the target fast charging duration. That is, when the target fast charging duration is shorter, the second current value is reduced by a larger reduction, while when the target fast charging duration is longer, the second current value is reduced by a smaller reduction, 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, the reduction of the second current value can be set to 5%, 4%, 3%, and 2% respectively.

[0086] Optionally, in one embodiment, the fast charging cycle mode provided by the present invention further includes step S103 before pre-charging the battery according to the first current value:

[0087] The first duration is determined based on the state of charge value of the battery.

[0088] In this step, because the charging rate performance of the battery varies at different states of charge, in order to balance the charging rate performance at each state of charge, a pre-charge duration that matches the actual charging performance of the battery can be set each time a fast charging cycle is executed, that is, the aforementioned first duration is determined.

[0089] In practical applications, because the higher the state of charge (SOC) value, the smaller the current that the battery can withstand without lithium plating, which means its rate performance is worse, the smaller the second current value, the smaller the difference between the first and second current values, and the less obvious the improvement in lithium plating effect brought about by low-current charging. Therefore, the first duration can be set to be negatively correlated with the SOC value of the battery, that is, the higher the SOC value of the battery, the shorter the first duration.

[0090] Optionally, in one specific embodiment, step S103 includes: determining that the first duration is greater than 0 when the state of charge value is less than the state of charge threshold; and determining that the first duration is 0 when the state of charge value is greater than the state of charge threshold.

[0091] In the above specific implementation, the state of charge threshold is the state of charge value of the battery that is prone to lithium plating and requires current-limited charging. This 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%.

[0092] In the above specific embodiments, when the state of charge (SOC) of the battery is less than the SOC threshold, the second current value of the formal charging is relatively large. In order to better alleviate the polarization phenomenon, the battery needs to be pre-charged first, that is, the first duration is set to be greater than 0. When the SOC of the battery is greater than or equal to the SOC threshold, the second current value of the formal charging is relatively small, so the polarization phenomenon caused by the formal charging is weaker, and there is no need to pre-charge the battery. That is, the first duration is set to 0, which can improve the charging efficiency.

[0093] For example, when the battery's state of charge is less than or equal to 80%, 0s < T2 ≤ 90s and 1s ≤ T1 ≤ 5s are set; while when the battery's state of charge is greater than 80%, 90s < T2 ≤ 120s and T1 = 0s are set.

[0094] Optionally, in one embodiment, the charging method provided by the present invention further includes steps S104 to S106 before pre-charging the battery according to a first current value:

[0095] Step S104: If the number of fast charging cycles n of the battery is greater than the fast charging cycle threshold N, determine the risk of lithium plating in the battery.

[0096] In this step, a fast charging count threshold N is preset. This fast charging count threshold is the number of times a fast charge will trigger the judgment of the lithium plating risk of the battery. The fast charging count threshold N can be calibrated according to the actual performance of the battery. For example, it can be 10 times. That is, after the battery is charged 10 times using the fast charging cycle mode in the charging method provided by the present invention, the judgment of the lithium plating risk of the battery is triggered. If the number of times the battery is charged using the fast charging cycle mode in the charging method provided by the present invention is less than 10 times, the step of judging the lithium plating risk of the battery is not executed.

[0097] Step S105: If the battery does not have a risk of lithium plating, continue to perform the step of charging the battery in fast charging cycle mode.

[0098] In this step, if it is determined that there is no risk of lithium plating in the battery, 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 charging cycle mode continues to meet the user's fast charging needs.

[0099] Step S106: If the battery has a risk of lithium plating, switch to slow charging cycle mode to charge the battery.

[0100] In this step, if it is determined that the battery is currently at risk of lithium plating, it means that the battery is in poor condition and cannot be fast charged. Therefore, the step is to switch to slow charging cycle mode to charge the battery in order to improve the lithium plating problem.

[0101] In the above implementation, the battery is only assessed for lithium plating risk after the number of times the fast charging cycle mode is set to reach the fast charging cycle threshold N. If there is no risk of lithium plating, the battery continues to be charged in the fast charging cycle mode; otherwise, it is charged in the slow charging cycle mode. This can promptly alleviate the polarization of the battery and improve its lithium plating problem.

[0102] Optionally, in one embodiment, step S104 specifically includes:

[0103] When nN is an integer multiple of m, the lithium plating risk of the battery is determined based on the battery's historical discharge capacity; m is the number of fast charges between two consecutive determinations of the battery's lithium plating risk, where n > m.

[0104] In this embodiment, the historical discharge capacity is the capacity value output by the battery after it is fully charged before the start of the current charging. Since the historical discharge capacity reflects the battery's capacity retention and change trend, the risk of lithium plating in the battery can be judged based on the historical discharge capacity.

[0105] In this implementation, after the battery has been charged N times in the fast charging cycle mode, the battery is triggered to determine whether there is a risk of lithium plating once the battery has been charged m times in the fast charging cycle mode. This allows the risk of lithium plating to be eliminated in a timely manner.

[0106] Optionally, in one specific implementation, m can be 10, which can minimize the number of judgments while ensuring timely detection of lithium plating risk, thereby reducing the computational load.

[0107] Optionally, in one specific embodiment, step S104 above includes steps S1041 to S1045:

[0108] S1041. Based on the historical discharge capacity of the battery, determine the discharge capacity C after the nmth fast charge cycle. n-m And the discharge capacity C after the nth fast charge cycle n .

[0109] In this step, since the historical discharge capacity records the capacity value output by the battery after each full charge, the discharge capacity C after the last (i.e., the previous) full charge in fast charging mode can be obtained based on this historical discharge capacity before performing the current charge. n And the discharge capacity C after the m-th charge from the end using fast charging mode. n-m .

[0110] S1042, Press (C) n-m -C n The current capacity cycle change rate K1 of the battery is calculated by ) / m.

[0111] In this step, the difference in battery discharge capacity after two fast charges that are m times apart is divided by m to obtain the current capacity cycle change rate of the battery.

[0112] 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, the capacity cycle change rate is defined as the reference capacity cycle change rate K2.

[0113] S1044. Based on the current capacity cycle change rate K1 and the baseline capacity cycle change rate K2, determine the lithium plating risk of the battery.

[0114] In this step, since the above-mentioned baseline capacity cycle change rate reflects the capacity change of the battery when it is charged in the fast charging cycle mode in the initial state, while the current capacity cycle change rate reflects the capacity change of the battery when it is charged in the fast charging cycle mode in the current state, comparing the baseline capacity cycle change rate with the current capacity cycle change rate can determine whether the current capacity cycle change rate of the battery is abnormal, that is, whether there is a risk of lithium plating.

[0115] Optionally, in one specific embodiment, step S1045 specifically includes:

[0116] If K1 > x*K2, the battery is deemed to have a risk of lithium plating, where x = 1.01 to 1.05.

[0117] In this specific implementation, x is a determination coefficient, which ranges from 1.01 to 1.05 depending on the battery system and materials. Specifically, when K1 > x*K2, it indicates an increased rate of capacity change, suggesting a significant risk of lithium plating in the battery, thus classifying the battery as having a lithium plating risk. Conversely, when K1 ≤ x*K2, it indicates that the rate of capacity change is not significant, and the risk of lithium plating is not obvious, thus classifying the battery as not having a lithium plating risk.

[0118] Optionally, in one embodiment, step S104 above further includes step S1046:

[0119] After charging the battery in slow charging cycle mode, the battery is determined to have no risk of lithium plating, so that the battery is charged in fast charging cycle mode the next time it needs to be charged.

[0120] In this embodiment, since charging the battery in slow charging cycle mode can effectively alleviate the polarization phenomenon of the battery and improve its lithium plating risk, theoretically, after charging the battery in slow charging cycle mode, the battery can continue to withstand the polarization effect brought about by fast charging cycle mode. Therefore, it is determined that the battery does not have the risk of lithium plating, so that the battery is charged in fast charging cycle mode the next time it needs to be charged.

[0121] Optionally, in one embodiment, the battery is charged in a slow charging cycle mode, including steps S1061 to S1063:

[0122] S1061. Obtain the state of charge value, attenuation coefficient and rated capacity of the battery.

[0123] In this step, the state of charge (SOC) refers to the SOC of the battery before the slow charge cycle mode, which can be directly obtained by the battery management system; the degradation coefficient and rated capacity are fixed performance parameters of the battery, which are related to the battery's structure and materials.

[0124] S1062. Determine the slow charging current based on the state of charge value, the attenuation coefficient, and the rated capacity.

[0125] In this step, since the charging current that can alleviate battery polarization and improve the risk of lithium plating is related to the battery's state of charge, degradation coefficient and rated capacity, the matching slow charging current can be determined based on the battery's actual state of charge, degradation coefficient and rated capacity.

[0126] S1063. Charge the battery according to the slow charging current.

[0127] In this step, the battery is charged according to the slow charging flow determined in step S1062 above.

[0128] In the above embodiments, 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, attenuation coefficient and rated capacity, and the battery is charged according to the slow charging current until its voltage reaches the preset charging cutoff voltage, which can better alleviate polarization and improve the lithium plating problem.

[0129] Optionally, in one specific embodiment, step S1062 includes steps S10621 to S10623:

[0130] Step S10621: Determine the actual charge interval to which the state of charge value belongs.

[0131] In this step, the battery's state of charge (SOC) value is pre-divided into multiple non-overlapping SOC intervals. After determining the battery's actual SOC value, the SOC interval in which the SOC value is located can be determined based on the relationship between the SOC value and the upper and lower limits of each SOC interval, which is the actual SOC interval.

[0132] Step S10622: Determine the actual slow charging coefficient corresponding to the actual charge interval according to the preset correspondence between the charge interval and the slow charging coefficient; wherein, in the preset correspondence, the upper limit value of each charge interval is negatively correlated with the slow charging coefficient.

[0133] In this step, a matching slow charging coefficient is set for each charge range 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 plating current when the battery capacity is higher, the charging current needs to be gradually reduced when the battery capacity is close to saturation. That is, the upper limit value of each charge range is negatively correlated with the slow charging coefficient.

[0134] Step S10623: Determine the slow charging current based on the product of the actual slow charging coefficient, the attenuation coefficient, and the rated capacity.

[0135] In this step, the actual slow charging coefficient is multiplied by the attenuation coefficient and the available capacity to calculate the matching slow charging current value.

[0136] For example, step S1062 specifically includes: determining the slow charging current to be YC when the state of charge (SCC) is in the range of 5% to 50%; determining the slow charging current to be 0.5YC when the SCC is in the range of 50% to 85%; and determining the slow charging current to be 0.2YC when the SCC is in the range of 85% to 97%, wherein Y = C n / C1, where C represents the rated capacity, Y represents the attenuation coefficient, and C n This indicates the discharge capacity after the battery was fully charged in fast charging mode. In other words, if slow charging cycle mode is triggered, the battery will be charged at a current of YC when its state of charge (SOC) is between 5% and 50%, at a current of 0.5YC when its SOC is between 50% and 85%, and at a current of 0.2YC when its SOC is between 85% and 97%.

[0137] In the above embodiments, 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. 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 cutoff voltage, which can better alleviate polarization and improve the lithium plating problem.

[0138] Optionally, in one specific embodiment, the above step S106 specifically includes: if the battery has a risk of lithium plating, update the number of slow charging cycles M = M + a, and charge the battery continuously M times in slow charging cycle mode, where a is the increase in the number of slow charging cycles after two consecutive judgments on the lithium plating risk of the battery.

[0139] In this specific implementation, the initial value of M is 0. This is because the continued emergence of lithium plating risk indicates a continuous deterioration in the health of the lithium battery. Setting the number of slow charging cycles to be executed after determining the presence of lithium plating risk gradually increases by a step size 'a', effectively addressing the gradually escalating lithium plating risk caused by fast charging. Here, 'a' can be 1, 2, or 3, etc.

[0140] Optionally, the M value can be set to less than or equal to 10. Since the demand for slow charging is relatively low in actual applications, the number of slow charging cycles is controlled within 10 weeks, that is, every 10 fast charging cycles are alternated with 1 slow charging cycle, and this will gradually continue until every 10 fast charging cycles are alternated with 10 slow charging cycles.

[0141] Optionally, in one embodiment, the charging method provided by the present invention further includes step S107 before charging the battery in a fast charging cycle mode:

[0142] The initial value of the second current value is updated based on the current capacity cycle change rate K1 and the reference capacity cycle change rate K2.

[0143] In this step, before starting to charge the battery in fast charging cycle mode, the initial formal charging current that matches the current lithium plating status of the battery is determined based on the current capacity cycle change rate and the reference capacity cycle change rate. That is, the initial value of the second current value mentioned above.

[0144] Optionally, in one specific embodiment, step S107 above is updated in one of the following ways:

[0145] Method 1: When K1≤K2, update the second current value Ib n =Ib n-m ;

[0146] Method 2: When K2≤K1≤xK2, update the second current value Ib. n = (1-K1)*Ib;

[0147] Method 3: When K1≥xK2, update the second current value Ib. n = (1-K1)*Ib*Υ;

[0148] Where Ib=α*C, K1 represents the current capacity cycle change rate, K2 represents the reference capacity cycle change rate, C represents the rated capacity, α represents the non-lithium plating coefficient, n represents the number of fast charging cycles, Υ represents the attenuation coefficient, and x=1.01~1.05.

[0149] In the above specific implementation, Ib≤Imax, where Imax is the maximum non-lithium-deposition current of the cell in a specific charging range, and Imax / C yields the non-lithium-deposition coefficient α.

[0150] This invention also 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 method described above.

[0151] For the above-described embodiments of electrical equipment, since they are basically similar to the embodiments of battery charging methods, the relevant parts can be referred to in the description of the method embodiments.

[0152] The present invention will be described in detail below through embodiments.

[0153] Example 1

[0154] (1) Preparation of positive electrode sheet

[0155] The positive electrode active material Li(Ni) 0.8 Mn 0.1 Co 0.1 O2 (NMC811), conductive agent acetylene black (Super P) and binder polyvinylidene fluoride (PVDF) are mixed evenly in a mass ratio of 94:3:3 and uniformly dispersed in 1-methyl-2-pyrrolidone (NMP) to form a uniform black slurry. The mixed slurry is coated on both sides of aluminum foil, and after baking, rolling, and cutting, the positive electrode sheet is obtained.

[0156] (2) Preparation of negative electrode sheet

[0157] Artificial graphite (AG), silicon oxide (SiO), acetylene black (Super P), and binder SBR were mixed evenly in a mass ratio of 84.6:9.4:3:3 and uniformly dispersed in deionized water to form a uniform black slurry. The slurry was then coated onto both sides of a copper foil, baked, rolled, and cut into sheets to obtain a surface density of 7 mg / cm³. 2 To the negative electrode plate.

[0158] (3) Preparation of electrolyte

[0159] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed evenly in a mass ratio of 30:30:40 to obtain a mixed solvent. Lithium salt LiPF6, or lithium salt LiPF6 and additives, are then dissolved in the obtained mixed solvent and mixed evenly to obtain an electrolyte. The concentration of LiPF6 in the electrolyte is 1 mol / L, and the mass percentage of LiODFB is 0.3%.

[0160] (4) Making a secondary battery

[0161] The prepared positive electrode, separator, and negative electrode are stacked in sequence, with the separator in the middle of the positive and negative electrode. After winding, hot pressing and shaping, and welding of the tabs, a bare battery is obtained. The bare battery is placed in an outer packaging aluminum-plastic film and baked in an oven at 85±10℃ for 24 hours. The electrolyte prepared above is injected into the dried battery, and the battery is allowed to stand, form, and be tested for capacity to complete the preparation of the lithium-ion soft pack battery.

[0162] Charge the battery at 25°C using the following steps:

[0163] (1) Charge with a constant current Ia = 0.3C for 1s;

[0164] (2) Charge with a constant current Ib = 1C for 10s;

[0165] (3) Discharge with a constant current of 0.01C for 3 seconds;

[0166] (4) Repeat steps (1) to (3) until the battery voltage reaches the upper limit of the cut-off working voltage to end the cycle.

[0167] The remaining embodiments and comparative examples are the same as in Embodiment 1, with differences shown in Table 1;

[0168] The secondary batteries prepared in the examples and comparative examples were tested using the Xinwei Battery Testing System. The lowest point potential of lithium plating on the negative electrode of the same battery under different test conditions was obtained and recorded in Table 1.

[0169] The secondary batteries prepared in the examples and comparative examples were tested using the Xinwei Battery Testing System to obtain the battery cycle retention rate of the same battery after 500 cycles, and the results are recorded in Table 1.

[0170] Table 1

[0171]

[0172] As can be seen from the test results in Table 1, Comparative Example 1 has the best retention rate after 500 cycles and the best negative electrode lithium plating potential, but the overall cycle period is long, which is not conducive to application. Comparative Examples 2, 3 and 4 have lower negative electrode lithium plating potentials and poor retention rates after 500 cycles, indicating that their fast charging cycle performance is poor. The cycle retention rates of the other examples are higher than those of the comparative examples, indicating that the fast charging method of alternating small and large current charging and discharging has a great improvement on cycle performance and a high cycle retention rate.

[0173] This invention also provides an electronic device, such as... Figure 2 As shown, it includes 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.

[0174] Memory 203 is used to store computer programs.

[0175] When processor 201 executes a program stored in memory 203, it performs the following steps:

[0176] Charge the battery using the fast charging cycle mode;

[0177] The fast charging cycle mode includes:

[0178] The battery is pre-charged for a first duration T1 according to a first current value, wherein 0s≤T1≤5s, and the first current value is 0.1C~0.5C;

[0179] After pre-charging the battery, the battery is formally charged for a second duration T2 according to the second current value, wherein 0s<T2≤120s, and the second current value is 1C~5C;

[0180] After the battery is formally charged, it is pre-discharged for a third duration T3 at a third current value, wherein 3s≤T3≤10s, and the third current value is 0.01C~0.1C.

[0181] After pre-discharging the battery, if the battery voltage is lower than the preset charging cutoff voltage, the step of pre-charging the battery at the first current value for a first duration T1 continues.

[0182] The processor 201 can also implement other steps in the above-mentioned battery charging method, which will not be described in detail here.

[0183] The communication bus mentioned in the above electronic devices can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. This communication bus can be divided into address bus, data bus, control bus, etc. For ease of illustration, only one thick line is used to represent it in the diagram, but this does not indicate that there is only one bus or one type of bus.

[0184] The communication interface is used for communication between the aforementioned electronic devices and other devices.

[0185] The memory may include random access memory (RAM) or non-volatile memory, such as at least one disk storage device. Optionally, the memory may also be at least one storage device located remotely from the aforementioned processor.

[0186] The processors mentioned above can be general-purpose processors, including central processing units (CPUs), network processors (NPs), etc.; they can also be digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0187] In another embodiment of the present invention, a computer-readable storage medium is also provided, which stores instructions that, when executed on a computer, cause the computer to perform the battery charging method described in the above embodiments.

[0188] In another embodiment of the present invention, a computer program product containing instructions is also provided, which, when run on a computer, causes the computer to execute the battery charging method described in the above embodiments.

[0189] In another embodiment of the present invention, an electrical device is also provided, including a battery and a battery management system, the battery management system including the electronic devices described in the above embodiments.

[0190] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially 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, all or part of the processes or functions described in the embodiments of the present invention are generated. 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. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. 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 integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid state disk (SSD)).

[0191] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0192] The various embodiments in this specification are described in a related manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. For embodiments of electrical equipment, electronic equipment, computer-readable storage media, and computer program products containing instructions therein, the descriptions are relatively simple because they are basically similar to the method embodiments; relevant parts can be referred to the descriptions of the method embodiments.

[0193] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

[0194] In summary, in this embodiment, by alternating charge and discharge cycles with varying currents during the fast charging cycle, polarization caused by high-current fast charging can be eliminated, interface lithium plating can be improved, abnormal cell temperature drops can be prevented, and regional differences in interface SOC caused by fast charging can be balanced, all while slightly increasing the charging time. In addition, low-current charging can reduce cell temperature rise differences, reduce regional overcharging and over-discharging phenomena, improve lithium plating, and also increase the battery's usable lifespan. Therefore, it solves the problem that existing charging methods cannot improve lithium plating on the negative electrode of lithium batteries while ensuring fast charging performance.

[0195] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present invention.

[0196] The present invention has provided a detailed description of a battery charging method and electrical device. Specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for charging a battery, characterized in that, include: Charge the battery using the fast charging cycle mode; The fast charging cycle mode includes the following steps: S111. Precharge the battery for a first duration T1 according to the first current value, wherein 0s≤T1≤5s, and the first current value is 0.1C~0.5C; S112. After pre-charging the battery, perform formal charging of the battery for a second duration T2 according to the second current value, wherein 0s<T2≤120s, and the second current value is 1C~5C. S113. After the battery is formally charged, the battery is pre-discharged for a third duration T3 according to the third current value, wherein 3s≤T3≤10s, and the third current value is 0.01C~0.1C. S114. After pre-discharging the battery, if the battery voltage is lower than the preset charging cutoff voltage, continue to execute steps S111-S113 until the battery voltage reaches the preset charging cutoff voltage. The fast charging cycle mode also includes: Before re-executing the step of pre-charging the battery at the first current value for a first duration T1, the second current value is reduced. Specifically, the second current value is reduced by a margin of 2-5%.

2. The charging method according to claim 1, characterized in that, Before pre-charging the battery at the first current value for a first duration T1, the method further includes the following steps: If the number of fast charging cycles (n) for the battery exceeds the fast charging cycle threshold (N), determine the lithium plating risk of the battery: If the battery does not have a risk of lithium plating, continue with the step of charging the battery in fast charging cycle mode; If the battery is at risk of lithium plating, switch to slow charge cycle mode to charge the battery.

3. The charging method according to claim 2, characterized in that, Assessing the lithium plating risk of the battery includes: When nN is an integer multiple of m, the lithium plating risk of the battery is determined based on the battery's historical discharge capacity; m is the number of fast charges between two consecutive determinations of the battery's lithium plating risk, where n > m.

4. The charging method according to claim 3, characterized in that, Based on the battery's historical discharge capacity, determine the battery's lithium plating risk, including: Based on the battery's historical discharge capacity, determine the discharge capacity C after the nmth fast charge cycle. n-m And the discharge capacity C after the nth fast charge cycle n ; Press (C) n-m -C n ) / m, calculate the current capacity cycle change rate K1 of the battery; Based on the battery's historical discharge capacity, when the battery's current capacity cycle change rate K1 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 based on the current capacity cycle change rate K1 and the baseline capacity cycle change rate K2.

5. The charging method according to claim 4, characterized in that, Based on the current capacity cycle change rate K1 and the baseline capacity cycle change rate K2, the lithium plating risk of the battery is determined, including: If K1 > x*K2, the battery is deemed to have a risk of lithium plating, where x = 1.01~1.

05.

6. The charging method according to claim 3, characterized in that, Assessing the lithium plating risk of the battery also includes: After charging the battery in slow charging cycle mode, the battery is determined to have no risk of lithium plating, so that the battery is charged in fast charging cycle mode the next time it needs to be charged.

7. The charging method according to claim 5, characterized in that, Before charging the battery in fast charging cycle mode, the following is also included: The initial value of the second current value is updated based on the current capacity cycle change rate K1 and the reference capacity cycle change rate K2, according to one of the following methods: 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 * ; Where Ib = α * C, K1 represents the current capacity cycle change rate, K2 represents the baseline capacity cycle change rate, C represents the rated capacity, α represents the non-lithium deposition coefficient, and n represents the number of fast charging cycles. This represents the attenuation coefficient.

8. The charging method according to claim 1, characterized in that, Before pre-charging the battery according to the first current value, the method further includes: Based on the battery's state of charge (SOC), the first duration is determined; and the target fast charging duration is obtained: Determining the first duration includes: If the state of charge value is less than the state of charge threshold, the first duration is determined to be greater than 0; If the state of charge value is greater than the state of charge threshold, the first duration is determined to be 0; Obtaining the target fast charging time includes: Based on the target fast charging duration, determine the first current value and the second duration; The first current value and the second duration are both negatively correlated with the target fast charging duration.

9. An electrical device, comprising a battery and a battery management system, characterized in that, The battery management system is used to charge the battery according to the method described in any one of claims 1 to 8.

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