Charging method, electronic device, charging apparatus, battery management system, electric device, medium, and program

Abstract

Disclosed in the present application are a charging method, an electronic device, a charging apparatus, a battery management system, an electric device, a computer-readable storage medium, and a computer program product. The charging method comprises: sequentially charging a battery according to a first current and a second current, wherein the current value of the second current is less than the current value of the first current, a charging duration for performing charging according to the first current is greater than or equal to 30s, the first current is greater than 1 C, and the current value of the second current is greater than 0. In the charging method, a charging stage using the second current is applied after a charging stage using the first current ends, and the current value of the second current is less than the current value of the first current. In the applied charging stage using the second current, the surface of an anode sheet of the battery that is close to a separator discharges towards a current collector side, which reduces the polarization of the battery, such that a direct linear relationship can be maintained between the terminal voltage of the battery and the charge or energy which has been input, thereby ensuring the cycle life of the battery.

Description

Charging method, electronic device, charging device, battery management system, electric device, medium and program

[0001] The present application claims priority to the Chinese patent application No. 2024113659557, filed on September 27, 2024, and entitled "Charging method, electronic device, device, system, electric device, medium and program", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the technical field of charging methods, and more particularly, to a charging method, an electronic device, a charging device, a battery management system, an electric device, a computer readable storage medium and a computer program product. BACKGROUND

[0003] When a battery is rapidly charged, the ion concentration at the electrode rapidly increases, leading to intensified polarization, which makes the battery terminal voltage and the charged electric quantity or energy unable to maintain a direct linear relationship, resulting in a decrease in charging efficiency and a decrease in the cycle life of the battery. SUMMARY

[0004] The present application provides a charging method, an electronic device, a charging device, a battery management system, an electric device, a computer readable storage medium and a computer program product.

[0005] The charging method provided by the present application includes sequentially charging a battery with a first current and a second current, wherein the current value of the second current is less than the current value of the first current, the charging time according to the first current is greater than or equal to 30 seconds, the first current is greater than 1C, and the current value of the second current is greater than 0.

[0006] The charging method provided by the present application includes sequentially charging a battery with a first current and a second current, wherein the current value of the second current is less than the current value of the first current, the charging time according to the first current is greater than or equal to 30 seconds, the first current is greater than 1C, and the current value of the second current is greater than 0.

[0007] In some embodiments, after the battery is sequentially charged with the first current and the second current, the battery is further charged with a third current, wherein the current value of the second current is less than the current value of the third current, and the third current is greater than 1C.

[0008] In some embodiments, the charging method comprises: the charging method comprises: N charging stages, N≥2 and is an integer; wherein each of the charging stages comprises: charging the battery in turn according to a first current and a second current, the current value of the second current is less than the current value of the first current, the charging time according to the first current is≥30s, and the current value of the second current is greater than 0; wherein the current value of the second current of the N-1th charging stage is less than the current value of the first current of the Nth charging stage.

[0009] In some embodiments, the charging method comprises: N charging stages, N≥2 and is an integer; each of the charging stages comprises: charging the battery according to a first current and a second current, at least one first period and a second period are set for each of the charging stages, and the second period is after at least one of the first periods, each of the charging stages comprises: charging the battery according to the first current in the first period and charging the battery according to the second current in the second period, wherein the current value of the second current of the N-1th charging stage is less than the current value of the first current of the Nth charging stage.

[0010] In some embodiments, the first period corresponding to each of the charging stages is the first period, and the last period corresponding to each of the charging stages is the second period.

[0011] In some embodiments, the first current is a constant current, and / or the second current is a constant current.

[0012] In some embodiments, the current value of the second current comprises a first value, a second value and a third value, the current value of the second current decreases from the first value to the second value, and then increases from the second value to the third value.

[0013] In some embodiments, the ratio of the current value of the second current to the current value of the first current ranges from 0.1 to 0.9.

[0014] In some embodiments, the ratio of the current value of the second current to the current value of the first current ranges from 0.5 to 0.7.

[0015] In some embodiments, the charging time according to the second current ranges from 1s to 20s.

[0016] In some embodiments, the charging time according to the second current ranges from 3s to 10s.

[0017] In some embodiments, the current value of the first current of the N-1th charging stage is greater than the current value of the first current of the Nth charging stage.

[0018] In some embodiments, the charging time length according to the first current is T1, and the charging time length according to the second current is T2, where T1 / T2≥5.

[0019] In some embodiments, the battery is a lithium ion battery.

[0020] In some embodiments, the capacity of the battery is ≥50 AH.

[0021] In some embodiments, the ratio of the current value of the second current to the current value of the first current is M, and the M is negatively correlated with at least one of the battery electrode parameter and the temperature of the battery, where the battery electrode parameter includes at least one of the conductivity, the area density, the compacted density and the thickness of the battery electrode.

[0022] In some embodiments, the ratio of the current value of the second current to the current value of the first current is M, and the variation range of the negative correlation between the M and the negative electrode electrode parameter is greater than the variation range of the negative correlation between the M and the positive electrode electrode parameter.

[0023] In some embodiments, the charging time length according to the first current is less than or equal to the charging cutoff time length, and the charging cutoff time length is the charging time length when the battery voltage reaches the battery cutoff voltage when the battery is charged according to the first current.

[0024] In some embodiments, the charging time length according to the first current is ≤250s.

[0025] The embodiments of the present application provide an electronic device, which comprises a memory configured to store a computer program and a processor, wherein the processor implements the above charging method when executing the computer program.

[0026] The embodiments of the present application provide a charging device configured to charge a battery in segments according to a charging sequence and using a multi-segment charging strategy, where each segment of the charging strategy comprises: charging the battery according to a first current and charging the battery according to a second current, and the current value of the second current is less than the current value of the first current and greater than 0.

[0027] The embodiments of the present application provide a battery management system comprising the electronic device or the charging device of the above embodiments.

[0028] The embodiment of the present application provides a power consumption device, which comprises a battery, a battery management system or a charging device.

[0029] The embodiment of the present application further provides a computer storage medium, which stores a computer program, and when the computer program is executed by one or more processors, the charging method of the embodiment of the present application is realized.

[0030] The embodiment of the present application further provides a computer program product, which comprises computer programs / instructions, and when the computer programs / instructions are executed by a processor, the charging method of the embodiment of the present application is realized.

[0031] The embodiment of the present application provides a charging method, an electronic device, a charging device, a battery management system, a power consumption device and a computer program product. The charging method comprises: charging a battery in a first current and a second current in sequence, wherein a current value of the second current is less than a current value of the first current, a charging time length according to the first current is greater than or equal to 30 seconds, the first current is greater than 1C, and the current value of the second current is greater than 0.

[0032] The charging method provided by the embodiment of the present application applies a charging stage of the second current after the charging stage of the first current ends, and the current value of the second current is less than the current value of the first current. The applied charging stage of the second current can make the surface of the negative pole piece of the battery close to the separator discharge to the current collector side, realize polarization reduction of the battery, make the battery end voltage and the charged electric quantity or energy maintain a direct linear relationship, and ensure the cycle life of the battery.

[0033] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0034] The above and / or additional aspects and advantages of the present application will become apparent and be readily appreciated from the following description, including the appended drawings.

[0035] FIG. 1 is a flowchart of a charging method according to an embodiment of the present application;

[0036] FIG. 2 is a charging current timing diagram of the charging method according to some embodiments of the present application;

[0037] FIG. 3 is a charging current timing diagram of the charging method according to some embodiments of the present application;

[0038] FIG. 4 is a charging current timing diagram of the charging method according to some embodiments of the present application;

[0039] FIG. 5 is a schematic diagram of a battery management system and a power consumption device according to an embodiment of the present application. DETAILED DESCRIPTION

[0040] Embodiments of the present application are described in detail below with reference to the accompanying drawings, in which the same or similar components have the same or similar designations and functions throughout, and embodiments described below are exemplary and are for explanation only, not to be construed as limiting the present application.

[0041] In the related art, when a battery is subjected to fast charging, the ion concentration at the electrode rapidly increases, leading to intensified polarization, which makes it impossible to maintain a direct linear relationship between the terminal voltage of the battery and the charged electric quantity or energy, resulting in a decrease in charging efficiency and a decrease in the cycle life of the battery.

[0042] To solve the problem of polarization of the battery, the embodiments of the present application provide a charging method for a battery (as shown in FIGS. 1-3), which can reduce the polarization of the battery, so that a direct linear relationship can be maintained between the terminal voltage of the battery and the charged electric quantity or energy, and the cycle life of the battery is ensured.

[0043] Referring to FIG. 1, the charging method according to the embodiments of the present application includes: charging the battery in turn according to a first current and a second current, wherein the current value of the second current is less than the current value of the first current, the charging time according to the first current is greater than or equal to 30 seconds, the first current is greater than 1C, and the current value of the second current is greater than 0.

[0044] The embodiments of the present application also provide an electronic device, which can include a memory configured to store a computer program and a processor. When the processor executes the computer program, the charging method according to the embodiments of the present application is implemented. Specifically, the processor can execute the computer program of "charging the battery in turn according to a first current and a second current, wherein the current value of the second current is less than the current value of the first current, the charging time according to the first current is greater than or equal to 30 seconds, the first current is greater than 1C, and the current value of the second current is greater than 0".

[0045] The embodiments of the present application also provide a charging device, which can charge a battery in turn according to a first current and a second current, wherein the current value of the second current is less than the current value of the first current, the charging time according to the first current is greater than or equal to 30 seconds, the first current is greater than 1C, and the current value of the second current is greater than 0. The charging device includes but is not limited to: an electric vehicle charging pile, a wireless charger, a mobile power supply, a charging cabinet, an energy storage cabinet, etc.

[0046] The embodiment of the present application further provides a computer storage medium, and the computer readable storage medium stores a computer program which, when executed by one or more processors, implements the charging method of the embodiment of the present application.

[0047] The embodiment of the present application further provides a computer program product comprising computer programs / instructions which, when executed by a processor, implement the charging method of the embodiment of the present application.

[0048] Specifically, when charging the battery according to the first current, the battery is subjected to fast charging, that is, the first current is greater than 1C, and the polarization of the battery can involve active polarization, concentration polarization and ohmic polarization.

[0049] Active polarization is the polarization caused by the fact that the electrochemical reaction rate of the positive and negative active materials is less than the electron movement rate. When the battery is subjected to fast charging, the electron movement rate is large. If the electron movement rate is greater than the electrochemical reaction rate of the positive and negative active materials, the enrichment of electrons on the interface will be caused, thereby changing the electrode potential.

[0050] Concentration polarization is the polarization caused by the concentration difference between the electrons and lithium ions. When the battery is subjected to fast charging, the concentration of the electrons is higher than that of the lithium ions. In the external circuit of the battery, when the electrons run from the positive electrode to the negative electrode interface, the enrichment of lithium ions occurs on the positive electrode side, which causes the positive electrode potential to shift to a higher direction, and the reduction of the concentration of lithium ions occurs on the negative electrode side, which causes the negative electrode potential to shift to a lower direction, thereby changing the electrode potential.

[0051] Ohmic polarization is the polarization caused by the resistance of the electrolyte, electrode material, separator and the contact resistance between various components. The resistance of the electrolyte, electrode material, separator and the contact resistance between various components is equivalent to an ohmic resistance. When the current flows through the ohmic resistance, the electrode produces an additional voltage drop, thereby changing the electrode potential.

[0052] When the battery is charged according to the second current, the positive and negative active materials will undergo electrochemical reactions in the case that the second current is greater than zero. Since the current value of the first current is large, that is, greater than 1C, the reaction of the active material in the thickness direction of the negative electrode is not uniform, and the reaction rate of the side away from the current collector is greater than that of the current collector side, which causes the state of charge (SOC) of the side away from the current collector to be higher. Since the current value of the second current is smaller than that of the first current, the reduction of the current will improve the uniformity of the reaction in the thickness direction of the negative electrode. At this time, the region with higher state of charge away from the current collector no longer undergoes the forward lithium intercalation electrochemical reaction, but undergoes the negative discharge electrochemical reaction. Therefore, the second current applied can make the side of the negative electrode active material away from the current collector discharge to the current collector side, thereby facilitating the reduction of the concentration polarization in the thickness direction and realizing the overall polarization reduction of the battery.

[0053] In addition, in the above embodiment, the first current greater than 1C means that the current value corresponding to any moment of the first current should be greater than the current value corresponding to charging the battery at a charging rate of 1C, so as to ensure that the effect of reducing the concentration polarization in the thickness direction can be improved when charging at the second current.

[0054] In addition, when charging the battery at the second current, the consumption rate of the reactant on the negative electrode surface is reduced, so that the reactant on the side of the current collector can be supplemented in time, thereby reducing the concentration polarization.

[0055] When charging the battery at the second current, the negative active material of the battery on the side away from the current collector discharges to the side of the current collector, so that the battery has a more uniform state of charge (SOC) and current density distribution in the thickness direction of the negative active material, improves the uniformity of the active material reaction in the thickness direction of the negative electrode, thereby reducing the concentration polarization.

[0056] It should be noted that the charging time of the first current should be greater than 30s. Because when the charging time of the first current is less than 30s, the polarization of the battery is still small, the SOC (state of charge) in the thickness direction of the negative electrode is relatively uniform, and the second current cannot make the negative electrode surface (the side away from the current collector) discharge to the side of the current collector, so there is no effect of reducing the polarization.

[0057] In addition, since the battery cannot be charged for an unlimited time, the charging time of the first current should be less than the charging time when the battery is charged at the first current to the voltage of the battery reaching the cut-off voltage of the battery, i.e. the charging cut-off time. When the actual voltage of the battery exceeds the cut-off voltage of the battery, there is a risk of lithium precipitation in the battery. Generally, in the embodiments disclosed in the present application, the charging time of the first current should be less than or equal to 250s. If the charging time of the first current exceeds 250s, the cut-off voltage of the battery may be exceeded, resulting in overcharging and lithium precipitation, affecting the service life of the battery.

[0058] Therefore, the charging method provided by the embodiments of the present application applies a second current in the charging phase after the end of the first current. The current value of the second current is less than the current value of the first current. The second current charging phase can make the surface of the negative electrode sheet close to the separator of the battery discharge to the side of the current collector, reduce the polarization of the battery, and ensure the cycle life of the battery.

[0059] In the above embodiments, 1C refers to the charge rate of the battery, specifically, the charge rate refers to the current value required by the battery to charge to its rated capacity within a specified time. The charge rate is represented by C, and the calculation formula is charge rate C = charging current (A) / battery rated capacity (Ah). For example, a battery with a rated capacity of 100 Ah is charged with a current of 100 A, and the charge rate is 1C.

[0060] In the embodiments of the present application, the current value of the second current is less than the current value of the first current, that is, the current value of the first current at any time is greater than the current value of the second current at any time, and then the second current applied can make the negative active material of the battery on the side away from the current collector to the side of the current collector to discharge, thereby facilitating the reduction of thickness direction concentration polarization and achieving the overall polarization reduction of the battery.

[0061] In the related art, lithium ion batteries are widely used in energy storage and electric vehicles and other fields due to their high energy density, high average output voltage, large output power, small self-discharge, superior cycle performance, fast charging and discharging, wide working temperature range, long service life and other advantages. When the lithium ion battery is rapidly charged, the ion concentration at the electrode increases rapidly, leading to increased polarization, resulting in reduced charging efficiency and reduced capacity of the lithium ion battery.

[0062] In addition, lithium metal is easily deposited on the surface of the negative electrode of the lithium ion battery (i.e., the surface of the negative active material layer away from the current collector), which on one hand reacts with the electrolyte to consume the active lithium of the positive electrode of the lithium ion battery, and on the other hand the growing lithium metal is easy to pierce the separator, leading to serious safety problems, so that the charging speed of the lithium ion battery is limited.

[0063] In order to solve the problem that lithium metal is easily deposited on the surface of the negative electrode of the lithium ion battery during rapid charging, in the related art, the lithium ion battery cell can be heated to a high temperature (45-60℃) by self-heating to improve the kinetics of lithium ion charging and discharging and reduce the risk of lithium deposition. However, the side reactions of the lithium ion battery increase under high temperature conditions, and the service life decreases.

[0064] The charging method of the embodiments of the present application can be used for lithium ion batteries.

[0065] Specifically, the positive active material used by the lithium ion battery includes but is not limited to lithium iron phosphate (LiFePO4), NCM ternary positive electrode material, lithium manganate (LiMn2O4), lithium-rich manganese-based material, and mixtures thereof.

[0066] The negative active material of the lithium ion battery includes, but is not limited to, graphite, silicon, lithium titanate or a mixture thereof. Taking the graphite as an example, the charging method provided by the embodiments of the present application can reduce the polarization of the lithium ion battery, so that the lithium battery has a more uniform state of charge (SOC) and current density distribution in the thickness direction of the graphite.

[0067] In addition, in other embodiments of the present application, the charging method of the embodiments of the present application is also applicable to non-lithium ion batteries, such as solid-state batteries, sodium ion batteries, etc. Specifically, the solid-state electrolyte includes, but is not limited to, sulfide, oxide, polymer solid-state electrolyte, the positive active material includes, but is not limited to, lithium iron phosphate (LiFePO4), ternary positive electrode material, lithium manganate (LiMn2O4), lithium-rich manganese-based and their mixtures, and the negative active material includes, but is not limited to, silicon-based material, carbon-based material, lithium metal or lithium titanate. The ionic conductivity of the solid-state electrolyte is generally small, the polarization is larger during fast charging, and the application of the second current also has the effect of reducing the polarization.

[0068] The charging method of the embodiments of the present application is also applicable to sodium ion batteries, and the positive active material of the sodium ion battery includes, but is not limited to, polyanion sodium battery positive material (NFPP), layered oxide sodium battery positive material (NFM), and Prussian blue sodium battery positive material, and the negative active material of the battery includes, but is not limited to, hard carbon, soft carbon, or their mixture and modified carbon material. The working principle of the sodium ion battery is similar to that of the lithium ion battery, and the problem of large polarization also exists during fast charging, and the application of the second battery also has the effect of reducing the polarization.

[0069] In some embodiments, the charging method further includes: after charging the battery with the first current and the second current in sequence, charging the battery with a third current, wherein the current value of the second current is less than the current value of the third current, and the third current is greater than 1C. By applying the third current after the second current, the current value of the second current is less than the current value of the third current, which can further optimize the charging strategy, shorten the charging time, reduce the polarization reaction of the battery and improve the cycle life of the battery. Wherein the current value of the second current is less than the current value of the third current includes the following cases: 1. When the second current is a constant current, the current value of the second current at any time is less than the current value of the third current at any time. 2. When the second current is a dynamic current, the current value of the third current at any time is greater than the minimum current value in the second current. In the above two cases, the third current can be a constant current or a dynamic current.

[0070] In some embodiments, the charging method comprises: N charging stages, N≥2 and is an integer; wherein each charging stage comprises: charging the battery in turn according to a first current and a second current, the current value of the second current being less than the current value of the first current, the charging time of the first current being≥30s, and the current value of the second current being greater than 0; wherein the current value of the second current in the N-1th charging stage is less than the current value of the first current in the Nth charging stage.

[0071] The third current in the N-1th charging stage can be the first current in the Nth stage. That is, in the Nth charging stage, the current value of the first current is greater than the current value of the second current in the N-1th charging stage and less than the current value of the first current in the N-1th charging stage. The charging time of the first current is≥30s, that is, the charging time of the third current is all≥30s.

[0072] Similarly, the charging time of the third current is less than or equal to the charging cutoff time, and the charging cutoff time is the charging time when the battery voltage reaches the battery cutoff voltage when the battery is charged according to the third current. In addition, in an embodiment, the charging time according to the third current is≤250s.

[0073] In each charging stage of the battery, a stage of charging according to the first current and a stage of charging according to the second current are included.

[0074] As described above, the charging method provided by the embodiments of the present application applies a charging stage of the second current after the charging stage of the first current ends, and the current value of the second current is less than the current value of the first current. The applied charging stage of the second current can make the surface of the negative electrode tab of the battery close to the separator side to the current collector side to be discharged, realize the polarization reduction of the battery, and ensure the cycle life of the battery.

[0075] Therefore, the polarization reduction of the battery can be realized in each charging stage, and the cycle life of the battery is ensured.

[0076] In the above embodiment, in the Nth charging stage, the current value of the first current at any time is greater than the current value of the second current at any time, and the applied second current can make the side of the negative active material of the battery away from the current collector to the current collector side to be discharged, thereby facilitating the reduction of the thickness direction concentration polarization and realizing the overall polarization reduction of the battery. That is, whether the first current and the second current are constant currents or dynamic currents, the current value of the first current at any time is greater than the current value of the second current at any time.

[0077] In the above embodiments, the current value of the second current in the N-1th charging stage is less than the current value of the first current in the Nth charging stage includes the following cases: 1, when the second current in the N-1th charging stage is a constant current, the current value of the second current at any time is less than the current value of the first current at any time in the Nth charging stage. 2, when the second current in the N-1th charging stage is a dynamic current, the current value of the first current at any time in the Nth charging stage is greater than the minimum current value in the second current in the N-1th charging stage. In the above two cases, the first current in the Nth charging stage can be a constant current or a dynamic current.

[0078] In some embodiments, the processor can execute a computer program according to the N charging stages, each charging stage includes: sequentially charging the battery according to the first current and the second current, the current value of the second current is less than the current value of the first current, the charging time of the first current is greater than or equal to 30s, and the current value of the second current is greater than 0; wherein the current value of the second current in the N-1th charging stage is less than the current value of the first current in the Nth charging stage.

[0079] In some embodiments, the charging device can charge the battery according to N charging stages, each charging stage includes: sequentially charging the battery according to the first current and the second current, the current value of the second current is less than the current value of the first current, the charging time of the first current is greater than or equal to 30s, and the current value of the second current is greater than 0; wherein the current value of the second current in the N-1th charging stage is less than the current value of the first current in the Nth charging stage. Specifically, taking FIG. 2 or FIG. 3 as an example, the lithium ion battery can include multiple charging stages, and each charging stage can correspond to a charging strategy. The charging device can charge the lithium ion battery in the corresponding charging stage according to the charging sequence and using the charging strategy.

[0080] For example, the lithium ion battery can include four charging stages. In the T1 period corresponding to the first charging stage, the lithium battery can charge the lithium ion battery according to the charging strategy S1. In the T2 period corresponding to the second charging stage, the lithium battery can charge the lithium ion battery according to the charging strategy S2. In the T3 period corresponding to the third charging stage, the lithium battery can charge the lithium ion battery according to the charging strategy S3. In the T4 period corresponding to the fourth charging stage, the lithium battery can charge the lithium ion battery according to the charging strategy S4.

[0081] The charging strategy S1, the charging strategy S2, the charging strategy S3 and the charging strategy S4 can all include: sequentially charging the battery according to the first current and the second current, the current value of the second current is less than the current value of the first current, the charging time of the first current is greater than or equal to 30s, and the current value of the second current is greater than 0.

[0082] In the T1 period corresponding to the first charging stage, the first current can be set as current I1, the second current can be set as current i1, current i1 is less than current I1, the charging time according to current I1 is greater than ≥ 30s, and the current value of current i1 is greater than 0. In the T2 period corresponding to the second charging stage, the first current can be set as current I2, the second current can be set as current i2, current i2 is less than current I2, the charging time according to current I2 is greater than ≥ 30s, and the current value of current i2 is greater than 0. In the T3 period corresponding to the third charging stage, the first current can be set as current I3, the second current can be set as current i3, current i3 is less than current I3, the charging time according to current I3 is greater than ≥ 30s, and the current value of current i3 is greater than 0. In the T4 period corresponding to the fourth charging stage, the first current can be set as current I4, the second current can be set as current i4, current i4 is less than current I4, the charging time according to current I4 is greater than ≥ 30s, and the current value of current i4 is greater than 0.

[0083] The current value of the second current of the N-1th charging stage is less than the current value of the first current of the Nth charging stage. In some embodiments, the current value of current I1 is less than the current value of current I2, which is less than the current value of current I3, which is less than the current value of current I4.

[0084] During the charging process of the battery, a small current charging stage is applied between two large current charging stages. The small current charging stage can cause the negative active material on the surface of the lithium ion battery (i.e., the surface of the side of the negative active material layer of the battery away from the current collector) to discharge to the side of the current collector, which can reduce or remove the polarization effect of the lithium ion battery.

[0085] For example, during the T1 period, the applied current i1 causes the negative active material on the surface of the lithium ion battery (i.e., the surface of the side of the negative active material layer of the battery away from the current collector) to discharge to the side of the current collector, which can reduce or remove the polarization effect of the lithium ion battery during the T1 period. The lithium ion battery has a more uniform state of charge (SOC) and current density distribution in the thickness direction of the negative active material during the T2 period, so as to prolong the charging time of the lithium ion battery during the T2 period.

[0086] Thus, the charging method provided by the embodiments of the present application can apply a second current on the basis of the stepped fast charging, and the applied second current can cause the negative active material on the surface of the lithium ion battery to discharge to the side of the current collector, thereby reducing the polarization of the lithium ion battery.

[0087] In addition, in an embodiment of the present application, as shown in FIG. 2, the second current comprises a falling current segment, a transition current segment and a rising current segment in sequence, specifically, the current value first decreases, then remains constant and then increases. In addition, in another embodiment of the present application, as shown in FIG. 3, the second current comprises a falling current segment and a rising current segment, specifically, the current value first decreases and then increases. In the above embodiments, the rising current segment, the transition current segment and the falling current segment can all be dynamic currents, i.e., not constant currents.

[0088] In an embodiment of the present application, when the first current and the second current are both constant currents, the starting current value and the terminal current value of the first current are equal to the current value at any time of the first current, and the starting current value and the terminal current value of the second current are equal to the current value at any time of the second current. Therefore, the charging phase is divided according to the starting current value of the first current, and each charging phase comprises the first current and the second current in sequence.

[0089] In some embodiments, the current waveform of the first current and the second current can be a curve waveform. A target current value is set in each charging phase. When the current value of the charging current in the charging phase is less than the target current value, the charging current is the second current, otherwise it is the first current, wherein the target current value can be determined according to actual needs, for example, it can be determined according to the charging current in the charging phase. Further, in an embodiment, the target current value can be determined according to the current value corresponding to the trough of the charging current (wherein if the charging current has multiple troughs with different current values, the trough with the minimum current value is used as the reference), in other embodiments, when the charging duration of the first current defined according to the current value corresponding to the trough of the charging current is less than 30s, the current value at the time when the charging duration of the charging current is equal to 30s can be used as the target current value. Of course, the target current value defined based on the above rules needs to ensure that after the target current value is determined, the charging current in the phase can be divided into A current curve and B current curve, the charging process B current curve is after the A current curve, and the current value at any time of the A charging curve is greater than the current value at any time of the B current curve.

[0090] Specifically, taking FIG. 4 as an example, in the charging phase, the waveform of the current I1 and the waveform of the current i1 are both curve waveforms. It should be noted that the waveform of the current I1 and the waveform of the current i1 can be a sine wave, a triangular wave or other curve waveforms, and are not limited to the waveforms shown in FIG. 4.

[0091] According to the charging current, the battery is charged from the starting time as a first charging stage, and in the first charging stage, the current value corresponding to the trough of the charging current is I1-min, that is, the target current value is I1-min. Therefore, in the first charging stage, the current waveform with a current value greater than I1-min is a current I1 waveform, and the current waveform with a current value less than I1-min is a current i1 waveform. Wherein, the demarcation point of current I1 and current i1 can be set as N1 point, and the time corresponding to N1 point is t-N1 time, therefore the charging current before t-N1 time (that is, the charging current between t-N0 time and t-N1 time) can be set as the first current of the first charging stage, that is, current I1; in addition, according to the current value corresponding to the trough of the charging current, the target current value is I1-min. The demarcation point N2 of the first charging stage and the second charging stage can also be determined, and the time corresponding to N2 point is t-N2 time, wherein the second charging stage is the charging stage after the first charging stage, therefore the charging current between t-N1 time and t-N2 time can be set as the second current of the first charging stage, that is, current i1; the charging current after t-N2 time can be set as the first current of the second charging stage, that is, current I2. In turn, the demarcation points of the first current and the second current of the Nth charging stage and the demarcation points of the second current of the N-1th charging stage and the first current of the Nth charging stage are determined according to the above embodiment.

[0092] In addition, if the first current charging duration divided by N1 is less than 30s in the above embodiment, the charging duration can be extended, for example, in FIG. 4, the first current and the second current are divided by N1' point as the demarcation point. The division method is consistent with the above method, and will not be described again. In turn, the demarcation points of the first current and the second current of the Nth charging stage and the demarcation points of the second current of the N-1th charging stage and the first current of the Nth charging stage are determined according to the above embodiment.

[0093] Further, in other embodiments of the present application, the first current and the second current can also be periodic current, for example: the first current and the second current are sine current, triangular wave current or square wave current.

[0094] In some embodiments, the charging method comprises: N charging stages, N≥2 and is an integer; each charging stage comprises: charging the battery according to the first current, charging the battery according to the second current, at least one first period and a second period are set for each charging stage, and the second period is after the at least one first period, and each charging stage comprises:

[0095] The battery is charged with a first current in a first time period and charged with a second current in a second time period, wherein the current value of the second current in the N-1th charging stage is less than the current value of the first current in the Nth charging stage.

[0096] The battery is charged with a first current in a first time period and charged with a second current in a second time period, wherein the current value of the second current in the N-1th charging stage is less than the current value of the first current in the Nth charging stage.

[0097] In some embodiments, the processor can execute a computer program of "the battery is charged with a first current in a first time period and charged with a second current in a second time period, wherein the current value of the second current in the N-1th charging stage is less than the current value of the first current in the Nth charging stage".

[0098] In some embodiments, the charging device can charge the battery with a first current in a first time period and charge the battery with a second current in a second time period, wherein the current value of the second current in the N-1th charging stage is less than the current value of the first current in the Nth charging stage.

[0099] Specifically, taking FIG. 2 or FIG. 3 as an example, in the T1 time period corresponding to the first charging stage, the first time period can be set as a t"1 time period, and the second time period can be set as a t11 time period.

[0100] The t"1 time period can be set as one, the t"1 time period can be set as multiple, and the t11 time period can be set after the first t"1 time period.

[0101] In the t"1 time period, the lithium ion battery is charged, the current collector side is charged to the negative active material on the surface of the lithium ion battery, and the lithium ion battery can generate a polarization effect during charging. In the t11 time period, the negative active material on the surface of the lithium ion battery (i.e. the surface of the side of the negative active material layer away from the current collector) is discharged to the current collector side to reduce the polarization of the lithium ion battery.

[0102] In the case of multiple t"1 time periods, a t11 time period can be provided between every two adjacent t"1 time periods. For example, the first t"1 time period can be denoted as a t"1a time period, the second t"1 time period can be denoted as a t"1b time period, and a t11 time period can be provided between the t"1a time period and the t"1b time period.

[0103] The second time period can also be set in multiple, each of which can be set in a period after a first time period. For example, in the T1 period, a total of three t"1 periods are included. The first t"1 period can be recorded as t"1a period, the second t"1 period can be recorded as t"1b period, and the third t"1 period can be recorded as t"1c period. A t11a period can be set between the t"1a period and the t"1b period, a t11b period can be set between the t"1b period and the t"1c period, and a t11c period can be set after the t"1c period.

[0104] In the t"1a period, the lithium ion battery is charged. In the t11a period, the negative active material on the surface of the lithium ion battery (i.e., the side surface of the negative active material layer away from the current collector) is discharged to the current collector side to reduce the polarization effect of the lithium battery in the t"1a period. In the t"1b period, the lithium ion battery continues to be charged. In the t11b period, the negative active material on the surface of the lithium ion battery (i.e., the side surface of the negative active material layer away from the current collector) is discharged to the current collector side to reduce the polarization effect of the lithium battery in the t"1b period. In the t11c period, the negative active material on the surface of the lithium ion battery (i.e., the side surface of the negative active material layer away from the current collector) is discharged to the current collector side to reduce the polarization effect of the lithium battery in the t"1c period.

[0105] In the T2 period corresponding to the second charging stage, the T3 period corresponding to the third charging stage, and the T4 period corresponding to the fourth charging stage, the first time period and the second time period can refer to the embodiments of the T1 period described above, and will not be described here.

[0106] In this way, in each charging stage, the lithium battery can include a plurality of first time periods for charging and a plurality of second time periods for reducing the polarization effect of the battery. After each charging of the lithium battery, the polarization effect of the lithium battery can be reduced, and the cycle life of the battery can be improved.

[0107] In some embodiments, the first time period corresponding to each charging stage is the first time period, and the last time period corresponding to each charging stage is the second time period.

[0108] Specifically, in the T1 time period corresponding to the first charging stage, the last time period can be set as t1-2 period, and the t1-2 period is the second time period described above, and the T2 period is entered after the t1-2 period. In the T2 time period corresponding to the second charging stage, the first time period can be set as t2-1 period, and the t2-1 period is the first time period described above.

[0109] Since the t1-2 period is the last period in the T1 period, the lithium ion battery before the t1-2 period can be in a fast charging state, the current density of the lithium ion battery surface is high, and the negative active material is easy to reach the lithium intercalation saturation. In the t1-2 period, the second current applied can cause the negative active material on the surface (i.e., the surface of the negative active material layer away from the current collector side) to discharge to the current collector side, reducing the saturation degree of the surface negative active material, thereby reducing the risk of lithium precipitation and improving the safety and life of the lithium ion battery.

[0110] After the t1-2 period enters the T2 period, the lithium ion battery has a more uniform state of charge (SOC) and current density distribution in the thickness direction of the negative active material in the T2 period, so as to prolong the first period of the lithium ion battery in the T2 period, i.e., the charging time of the battery in the second charging stage can be prolonged, the charging efficiency of the lithium ion battery is improved, and the fast charging of the lithium ion battery is realized.

[0111] Similarly, in the T2 period corresponding to the second charging stage, the last period is the second period, in the T3 period corresponding to the third charging stage, the first period is the first period, the charging time of the battery in the third charging stage can be prolonged, the charging efficiency of the lithium ion battery is improved, and the fast charging of the lithium ion battery is realized. In the T3 period corresponding to the third charging stage, the last period is the second period, in the T4 period corresponding to the fourth charging stage, the first period is the first period, the charging time of the battery in the fourth charging stage can be prolonged, the charging efficiency of the lithium ion battery is improved, and the fast charging of the lithium ion battery is realized.

[0112] In this way, the charging method can prolong the charging time of the battery in multiple charging stages, improve the charging efficiency of the lithium ion battery, and realize the fast charging of the lithium ion battery.

[0113] Further, in the above embodiment, in one charging stage, when the first current is a dynamic current, for example, the first current is a sine current, a triangular wave current or a square wave current. When the first current includes multiple periods in turn, the corresponding periods can be divided according to a preset rule. The preset rule can be determined according to actual needs. Further, in an embodiment of the present application, taking the first current including multiple sine currents with different amplitudes as an example, if multiple sine currents with different amplitudes appear in the first current, multiple first current charging periods can be divided by the trough values of each sine current. For example, the battery is charged according to the first current, and three sine currents appear in the whole charging process in turn. The time points when the trough values of the three sine currents match are A time point, B time point and C time point. Therefore, the charging stage includes the following three first periods: the period from the start time of the first current to the A time point, the period from the A time point to the B time point, and the period from the B time point to the C time point.

[0114] In some embodiments, the first current is a constant current, and / or the second current is a constant current.

[0115] Specifically, the first current can be set as a constant current, i.e., the fast charging of the battery can be implemented according to a constant current in the first time period. The charging method can apply a second current to reduce the polarization of the lithium ion battery on the basis of the step fast charging of each constant current.

[0116] The second current can be set as a constant current, and the charging device can apply a pulse signal of the second current to the lithium ion battery in the second time period, charge the lithium ion battery based on a square wave charging strategy, reduce or remove the polarization effect of the lithium ion battery, and improve the performance of the lithium ion battery.

[0117] In some embodiments, the first current can also be set as a current with a varying current value, and the current value of the first current can change with time. The corresponding relationship between the current value In of the first current and the time t can be In = A * B C*t + D, where a, b, A, B, C, and D can be positive or negative real numbers, or zero. The specific values of a, b, A, B, C, and D can be determined according to the actual design of the battery cell.

[0118] Referring to FIG. 3, in some embodiments, the current value of the second current includes a first value, a second value, and a third value, and the current value of the second current decreases from the first value to the second value and then increases from the second value to the third value.

[0119] Specifically, the second current can be set as a current with a varying current value, and the charging device can provide a varying current signal to the lithium ion battery in the second time period to reduce or remove the polarization effect of the lithium ion battery.

[0120] For example, in the T1 time period, the first value corresponding to the current i1 can be set as i1a, the second value can be set as i1b, and the second value can be set as i1c. In the t11 time period, the current value of the current i1 decreases from i1a to i1b and then increases from i1b to i1c.

[0121] In some embodiments of the present application, the current value of the second current linearly decreases from the first value to the second value, and then linearly increases from the second value to the third value. In the first charging stage, the current value of the current il can linearly decrease from ila to ilb, and then linearly increase from ilb to ilc. In the second charging stage, the current value of the current i2 can linearly decrease from i2a to i2b, and then linearly increase from i2b to i2c. In the third charging stage, the current value of the current i3 can linearly decrease from i3a to i3b, and then linearly increase from i3b to i3c. In the fourth charging stage, the current value of the current i4 can linearly decrease from i4a to i4b, and then linearly increase from i4b to i4c.

[0122] The charging device can provide the triangular wave current signal to the lithium ion battery in the second period, reducing or removing the polarization effect of the lithium ion battery. The triangular wave current can automatically adjust the charging speed according to the state of the battery during the charging process, thereby avoiding overcharging and excessive internal temperature rise of the battery, and also helping to prolong the service life of the battery.

[0123] The charging device can provide the triangular wave current signal to the lithium ion battery in the second period, reducing or removing the polarization effect of the lithium ion battery. The triangular wave current can automatically adjust the charging speed according to the state of the battery during the charging process, thereby avoiding overcharging and excessive internal temperature rise of the battery, and also helping to prolong the service life of the battery.

[0124] In some embodiments, the ratio of the current value of the second current to the current value of the first current is in the range of [0.1-0.9]. Specifically, when the ratio of the current value of the second current to the current value of the first current is in the range of [0.1-0.9] and the charging method disclosed in the present application can further shorten the fast charging time, reduce the problem of battery polarization, and improve the reduction speed of the battery capacity retention rate.

[0125] Further, in an embodiment of the present application, the ratio of the current value of the second current to the current value of the first current is in the range of [0.5-0.7]. Specifically, when the ratio of the current value of the second current to the current value of the first current is in the range of [0.5-0.7] and the charging method disclosed in the present application can further shorten the fast charging time, reduce the problem of battery polarization, and improve the reduction speed of the battery capacity retention rate.

[0126] In the above embodiments, if the second current is a dynamic current, the current value of the second current can be an average current value or a minimum current value. Specifically, if the second current is a sinusoidal current signal, the current value of the second current is the average current value of the sinusoidal current signal. If the second current is a triangular wave current signal, the current value of the second current is the minimum current value of the triangular wave. In addition, if the second current is a constant current, the current value of the second current is the actual current value.

[0127] In further embodiments, in the above embodiments, the current value of the first current is the current value at the end point of the first current, or the current value of the first current at the time when the first current is converted to the second current, or the current value corresponding to the boundary point of the first current and the second current, which can be determined with reference to the foregoing part.

[0128] In addition, in the above embodiments, the ratio of the current value of the second current to the current value of the first current can be determined according to the charge rate of the second current and the charge rate of the first current. Specifically, since the charge rate of the battery is equal to the current / battery capacity, when the battery capacity is consistent, the ratio of the current is equal to the ratio of the charge rate.

[0129] In some embodiments, the charging duration of charging the battery according to the second current ranges from 1s to 20s. Specifically, when the charging duration of charging the battery according to the second current ranges from 1s to 20s and according to the charging method disclosed in the present application, the fast charging time can be further shortened, the problem of battery polarization can be reduced, and the reduction speed of the battery capacity retention rate can be improved.

[0130] Further, in an embodiment of the present application, the charging duration of charging the battery according to the second current ranges from 3s to 10s. Specifically, when the charging duration of charging the battery according to the second current ranges from 3s to 10s and according to the charging method disclosed in the present application, the fast charging time can be further shortened, the problem of battery polarization can be reduced, and the reduction speed of the battery capacity retention rate can be improved.

[0131] In the above embodiments, the charging duration of charging the battery according to the second current in the current charging stage can be determined according to the time duration between the time corresponding to the end point current value of the first current in the current charging stage and the time corresponding to the start point current value of the first current in the next charging stage. Specifically, the charging duration of charging the battery according to the second current can be determined according to the boundary point of the first current and the second current in the current charging stage and the boundary point of the second current in the current charging stage and the first current in the next charging stage, for example, as shown in FIG. 4, the charging duration of charging the battery according to the second current is equal to the difference between the time value corresponding to t-N2 and the time value corresponding to t-N1.

[0132] In an embodiment of the present application, the current value of the first current is greater than or equal to 2C. Specifically, when the current value of the first current is greater than or equal to 2C and the charging method disclosed in the present application can further shorten the fast charging time, reduce the problem of battery polarization, and thus improve the speed of reduction of the battery capacity retention rate.

[0133] In an embodiment of the present application, the charging time according to the first current is T1, and the charging time according to the second current is T2, where T1 / T2≥5. Specifically, when the charging time according to the first current is T1, and the charging time according to the second current is T2, where T1 / T2≥5 and the charging method disclosed in the present application can further shorten the fast charging time, reduce the problem of battery polarization, and thus improve the speed of reduction of the battery capacity retention rate.

[0134] In the above embodiment, the charging time of the battery according to the first current in the current charging stage can be determined according to the time length between the time corresponding to the starting current value of the first current in the same charging stage and the time corresponding to the terminal current value of the first current. Specifically, the charging time of the battery according to the first current can be determined according to the demarcation point of the first current (or the initial charging time) in the current charging stage and the demarcation point of the second current in the previous charging stage, and the demarcation point of the first current and the second current in the current charging stage, for example, as shown in FIG. 4, the charging time of the battery according to the first current is equal to the difference between the time value corresponding to t-N0 and the time value corresponding to t-N1.

[0135] In the above embodiment, the charging time of the battery according to the second current in the current charging stage can be determined according to the time length between the time corresponding to the terminal current value of the first current in the current charging stage and the time corresponding to the starting current value of the first current in the next charging stage. Specifically, the charging time of the battery according to the second current can be determined according to the demarcation point of the first current and the second current in the current charging stage, and the demarcation point of the second current in the current charging stage and the first current in the next charging stage, for example, as shown in FIG. 4, the charging time of the battery according to the second current is equal to the difference between the time value corresponding to t-N2 and the time value corresponding to t-N1.

[0136] In some embodiments, the current value of the first current corresponding to each charging stage gradually decreases. That is, the current value of the first current of the N-1th charging stage is greater than the current value of the first current of the Nth charging stage. The step charging by large current can further shorten the fast charging time, reduce the risk of battery polarization, and improve the cycle life of the battery. As the battery charging time is longer, the battery capacity gradually rises, and the current value of the first current corresponding to each charging stage gradually decreases, which can prevent the battery from overcharging and reduce the risk of battery polarization, thereby improving the cycle life of the battery.

[0137] Specifically, the current I1 can be set to be greater than the current I2, the current I2 can be set to be greater than the current I3, and the current I3 can be set to be greater than the current I4.

[0138] In an embodiment disclosed in the present application, the ratio of the current value of the second current to the current value of the first current is M, and M is negatively correlated with at least one of a parameter of a battery pole piece and a temperature of the battery, wherein the parameter of the battery pole piece includes at least one of the electrical conductivity, the area density, the compactness density and the thickness of the battery pole piece. Specifically, when the parameter of the battery pole piece is larger, the value of M should be smaller, to improve the discharge capacity of the negative electrode active material to the current collector side, ensure the best SOC balancing effect, reduce the risk of lithium precipitation in the fast charging process, and prolong the battery life.

[0139] Further, in an embodiment disclosed in the present application, the ratio of the current value of the second current to the current value of the first current is M, and the change amplitude of the negative correlation between M and the parameter of the negative electrode pole piece is greater than the change amplitude of the negative correlation between M and the parameter of the positive electrode pole piece. Specifically, since polarization and lithium precipitation mainly occur on the negative electrode pole piece side of the battery, adjusting the positive and negative electrode pole piece parameters will have a greater change in the value of M than adjusting the positive electrode pole piece parameters, thereby shortening the fast charging time, reducing the risk of battery polarization, and improving the cycle life of the battery.

[0140] Lithium iron phosphate batteries and ternary lithium batteries can be used as experimental objects to compare the fast charging time and life decay under different charging strategies, and determine the preferred embodiment of the charging strategy.

[0141] The following is a specific test scheme. The experimental object battery uses lithium iron phosphate LiFePO4 / NCM ternary positive electrode material as the positive electrode material and graphite as the negative electrode material. The battery participating in the test is placed in a 25℃ environment and subjected to the following charging and discharging test.

[0142] In embodiment 1, the experimental method of battery fast charging includes: charging a battery with a chemical system of lithium iron phosphate LiFePO4 and a capacity of 100 AH at a large current I1 of 7C for 100s, and then charging at a small current I2 of 3.5C (i.e. the current value of the small current is 0.5 times the current value of the large current) for 1s; then charging at a large current I1 of 6.5C for 100s, and then charging at a small current I2 of 3.25C for 1s; then charging at a large current I1 of 6C for 100s, and then charging at a small current I2 of 3C for 1s, and so on (i.e. the current value of each large current is equal to the current value of the previous large current-0.5C, and the current value of the small current is 0.5 times the current value of the previous large current) until the battery is charged from 10% SOC to 80% SOC, and then stopped, and the time in the SOC interval is calculated, which is the fast charging time.

[0143] Cycle life test: charge according to the above charging method, and then discharge at a discharge current of 0.33C when the charge is 80% SOC, until the battery voltage reaches 2.0V. Repeat the above charging steps until the cycle number is greater than 500 / 1000 times (or the capacity retention rate of the battery is less than 80%), and calculate the capacity retention rate of the battery at the same time.

[0144] The capacity retention rate is calculated as follows: the capacity of the battery before testing is Q0 (in addition, the battery capacity Q0 can also be the nominal capacity of the battery), then the battery is charged from 10% SOC to 80% SOC based on the above charging method, and then discharged to 10% SOC at a discharge rate of 1 / 3C, and then cycled 500 times, and then the battery is tested at a rate of 1 / 3C after 500 cycles (capacity calibration), and the calibrated capacity is Q500, and the calibrated capacity after 1000 cycles is Q1000. The capacity retention rate of the 500th cycle is Q500 / Q0*100%, and the capacity retention rate of the 1000th cycle is Q1000 / Q0*100%.

[0145] Embodiments 2-42 and comparative examples 1-20 all perform charging and discharging tests on lithium iron phosphate batteries according to the steps of embodiment 1, wherein the difference lies in the charging rate of the large current (i.e. I1), the ratio between the charging rate of the small current (i.e. I2) and the charging rate of the large current, the charging time of the large current, the charging time of the small current, and the ratio between the charging time of the large current and the charging time of the small current. The following table (experimental data of lithium iron phosphate batteries) can be obtained, in which K1 can represent the ratio between the charging rate of the second current and the charging rate of the first current, T2 can represent the charging time of the second current, K2 can represent the ratio between the charging time of the first current and the charging time of the second current, and T1 can represent the charging time of the first current.

[0146] In Table 2, Examples 1-42 and Comparative Examples 1-20 are all subjected to charge-discharge test according to the procedure of Example 1 in Table 1 above, wherein the difference is the charge rate of the large current (i.e. I1) and the ratio between the charge rate of the small current (i.e. I2) and the charge rate of the large current, the charge time of the large current, the charge time of the small current and the charge time of the large current and the charge time of the small current are different. The following Table 2 (experimental data of ternary lithium battery) can be obtained, in which, in Table 2, K3 can represent the ratio between the charge rate of the second current and the charge rate of the first current, T4 can represent the charge time of the second current, K4 can represent the ratio between the charge time of the first current and the charge time of the second current, and T3 can represent the charge time of the first current.

[0147] Table 1

[0148] Table 2

[0149] Referring to Table 1 and Table 2, it can be known from the comparison between Examples 1-16, 21-33 and Comparative Examples 12, 14, 16, 18-20 that, compared with charging according to the first current, then standing, and then charging according to the first current, in turn charging the battery according to the first current and the second current, wherein the current value of the second current is less than the current value of the first current, and the current value of the second current is greater than 0, the fast charging time can be improved, and the problem of battery polarization can be reduced, thereby improving the reduction speed of the battery capacity retention rate. In addition, whether it is 2C, 3C, or 4C or above, the charging method disclosed in the present application can shorten the fast charging time, reduce the problem of battery polarization, and improve the reduction speed of the battery capacity retention rate.

[0150] It can be seen from the comparison between Examples 1-16, 21-33 and Comparative Examples 11, 13, 15 and 17 that, compared with charging according to the stepped first current, the charging method disclosed in the embodiments of the application, i.e., charging the battery according to the first current and the second current in sequence, wherein the current value of the second current is less than the current value of the first current and the current value of the second current is greater than 0, can shorten the fast charging time and reduce the problem of battery polarization and further improve the reduction speed of the battery capacity retention rate. In addition, whether it is 2C, 3C, or 4C or above, the charging method disclosed in the application can shorten the fast charging time and reduce the problem of battery polarization and further improve the reduction speed of the battery capacity retention rate.

[0151] In the embodiments disclosed in the application, the first current is greater than 1C. Specifically, it can be seen from Comparative Examples 9 and 10 that, when the first current is 1C, there is little difference in the charging time and capacity retention rate of the battery between charging the battery according to the charging method disclosed in the application and directly charging the battery with the first current. If the first current is 1C, the fast charging time cannot be shortened, and the problem of battery polarization cannot be reduced and the reduction speed of the battery capacity retention rate cannot be improved. As can be seen from Example 12 and Comparative Example 13, when the first current of the battery is greater than 1C, the fast charging time can be shortened, and the problem of battery polarization can be reduced and the reduction speed of the battery capacity retention rate can be improved.

[0152] In the embodiments disclosed in the application, the charging time of the first current is greater than or equal to 30s. Specifically, it can be seen from Examples 5, 34-36 and Comparative Examples 1-8 that, when the current of the first current is greater than or equal to 30s, the charging method disclosed in the application can shorten the fast charging time and reduce the problem of battery polarization and further improve the reduction speed of the battery capacity retention rate.

[0153] In an embodiment disclosed in the application, the ratio of the current value of the second current to the current value of the first current is in the range of [0.1-0.9], i.e., the charging rate of the second current to the charging rate of the first current is in the range of [0.1-0.9]. Specifically, it can be seen from the comparison of Examples 11-16 and 28-29 that, when the ratio of the current value of the second current to the current value of the first current is in the range of [0.1-0.9], the charging method disclosed in the application can further shorten the fast charging time and reduce the problem of battery polarization and further improve the reduction speed of the battery capacity retention rate.

[0154] In further embodiments, the ratio of the current value of the second current to the current value of the first current ranges from 0.5 to 0.7, i.e., the ratio of the charging rate of the second current to the charging rate of the first current ranges from 0.5 to 0.7. Specifically, as can be seen from the comparison of embodiments 11-16, when the ratio of the current value of the second current to the current value of the first current ranges from 0.5 to 0.7, and the charging method disclosed herein is used, the fast charging time can be further shortened, the problem of battery polarization can be reduced, and the rate of decrease of the battery capacity retention rate can be improved.

[0155] In an embodiment disclosed herein, the charging time of the second current ranges from 1 s to 20 s. Specifically, as can be seen from the comparison of embodiments 1-8, when the charging time of the second current ranges from 1 s to 20 s, and the charging method disclosed herein is used, the fast charging time can be further shortened, the problem of battery polarization can be reduced, and the rate of decrease of the battery capacity retention rate can be improved.

[0156] In further embodiments, the charging time of the second current ranges from 3 s to 10 s. Specifically, as can be seen from the comparison of embodiments 1-8, when the charging time of the second current ranges from 3 s to 10 s, and the charging method disclosed herein is used, the fast charging time can be further shortened, the problem of battery polarization can be reduced, and the rate of decrease of the battery capacity retention rate can be improved.

[0157] In addition, as can be seen from the comparison between embodiments 1-16 and 25-33, when the ratio of the current value of the second current to the current value of the first current ranges from 0.1 to 0.9 and the charging time of the second current ranges from 1 s to 20 s, and the charging method disclosed herein is used, the fast charging time can be effectively shortened, the problem of battery polarization can be reduced, and the rate of decrease of the battery capacity retention rate can be improved.

[0158] In an embodiment disclosed herein, the current value of the first current in the N-1th charging stage is greater than the current value of the first current in the Nth charging stage. Specifically, as can be seen from the comparison of embodiments 3 / 7 / 11 / 13 / 16 and embodiments 17-24, compared with direct charging with the first current, when the current value of the first current in the N-1th charging stage is greater than the current value of the first current in the Nth charging stage, the fast charging time can be further shortened, the problem of battery polarization can be reduced, and the rate of decrease of the battery capacity retention rate can be improved.

[0159] In an embodiment, the ratio of the charging time according to the first current to the charging time according to the second current is ≥ 5. Specifically, as can be seen from embodiments 37-42, when the ratio of the charging time according to the first current to the charging time according to the second current is ≥ 5 and the charging method disclosed in the present application can further shorten the fast charging time, reduce the problem of battery polarization, and improve the reduction speed of battery capacity retention rate.

[0160] In addition, as can be seen from the above description, the above relationship is satisfied for the embodiments in Table 1 and Table 2, so it can be known that whether it is an LFP system battery or a ternary system battery, the charging method disclosed in the present application can effectively shorten the fast charging time, reduce the problem of battery polarization, and improve the reduction speed of battery capacity retention rate. In further, for other system batteries (such as sodium ion batteries, solid state batteries, etc.), the charging method disclosed in the present application can also effectively shorten the fast charging time, reduce the problem of battery polarization, and improve the reduction speed of battery capacity retention rate.

[0161] The charging method provided by the embodiments of the present application can be applied to all conventional fast charging strategies of I1≥I2≥I3≥...≥In, and In can be selected according to the actual charging capacity of the lithium ion battery, that is, it is applicable to all charging rates within the safe charging current of the product.

[0162] Referring to FIG. 5, the embodiments of the present application provide a battery management system 20 and a power utilization device 100, the battery management system 20 comprising the electronic device or the charging device of the above-mentioned embodiments. The power utilization device 100 can comprise the battery 10, the battery management system 20 or the charging device provided by the embodiments of the present application. The charging device includes but is not limited to: an electric vehicle charging pile, a wireless charger, a mobile power supply, a charging cabinet, an energy storage cabinet, etc. The power utilization device 100 includes but is not limited to: an electric vehicle, a household energy storage system, an uninterruptible power supply (UPS, Uninterruptible Power Supply), a flywheel energy storage system, a pumped storage power station, etc.

[0163] The battery management system 20 and the power utilization device 100 of the embodiments of the present application can charge the battery based on the charging method of the above-mentioned embodiments, and the battery management system 20 and the power utilization device 100 include all technical effects of the charging method of the embodiments of the present application, which are not described here.

[0164] In the description of the specification, the description of the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the description of the specification, the above terms are not necessarily intended to refer to the same embodiment or example. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples without contradiction and combination.

[0165] In addition, the term "connection" should be understood broadly, for example, it can include fixed connection, or detachable connection, or integral connection; it can include direct connection, or indirect connection through intermediate medium, or it can include the communication inside two elements. For the person skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0166] In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "multiple" is at least two, for example, two, three, etc., unless otherwise specifically limited.

[0167] Any process or method descriptions in flow charts or described elsewhere herein can be understood as representing code modules, segments, or portions of code that include one or more executable instructions for performing specific logic functions or steps in the process, and that the alternate implementations can be realized by the alternative order of the steps, the selection or omission of steps, and / or the inclusion of additional or alternative steps as would be understood by one of ordinary skill in the art to achieve the functions described in the specification.

[0168] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the present application, and the person skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present application.

Claims

1. A method of charging a battery, characterized by, The method comprises: charging the battery in sequence according to a first current and a second current, wherein the current value of the second current is less than the current value of the first current, the charging time according to the first current is greater than or equal to 30 seconds, the first current is greater than 1C, and the current value of the second current is greater than 0.

2. The charging method according to claim 1, characterized by, After the battery is charged in sequence according to the first current and the second current, the battery is further charged according to a third current, wherein the current value of the second current is less than the current value of the third current, and the third current is greater than 1C.

3. The charging method according to claim 1, characterized by, The charging method comprises: N charging stages, wherein N is an integer greater than or equal to 2; each charging stage comprises: charging the battery in sequence according to a first current and a second current, wherein the current value of the second current is less than the current value of the first current, the charging time according to the first current is greater than or equal to 30 seconds, and the current value of the second current is greater than 0. The current value of the second current in the N-1th charging stage is less than the current value of the first current in the Nth charging stage.

4. The charging method according to claim 1, characterized by, The charging method comprises: N charging stages, wherein N is an integer greater than or equal to 2; each charging stage comprises: charging the battery according to a first current, charging the battery according to a second current, at least one first time period and a second time period are set for each charging stage, and the second time period is after the at least one first time period, and each charging stage comprises: charging the battery according to the first current in the first time period and charging the battery according to the second current in the second time period, wherein the current value of the second current in the N-1th charging stage is less than the current value of the first current in the Nth charging stage.

5. The charging method according to claim 4, characterized by, The first time period corresponding to each charging stage is the first time period, and the last time period corresponding to each charging stage is the second time period.

6. The charging method according to any one of claims 1 to 5, characterized in that, The first current is a constant current, and / or the second current is a constant current.

7. The charging method according to claim 1, characterized by, The current value of the second current comprises a first value, a second value and a third value, the current value of the second current decreases from the first value to the second value, and then increases from the second value to the third value.

8. The charging method according to claim 1, characterized by, The ratio of the current value of the second current to the current value of the first current ranges from 0.1 to 0.

9.

9. The charging method according to claim 8, characterized by, The ratio of the current value of the second current to the current value of the first current ranges from 0.5 to 0.

7.

10. The charging method according to claim 1 or 8, characterized by, The charging time according to the second current ranges from 1 second to 20 seconds.

11. The charging method according to claim 10, characterized by, The charging time according to the second current ranges from 3 seconds to 10 seconds.

12. The charging method according to claim 3 or 4, characterized by, The current value of the first current in the N-1th charging stage is greater than the current value of the first current in the Nth charging stage.

13. The charging method according to claim 1 or 8, characterized by, The current value of the first current is greater than or equal to 2C.

14. The charging method according to claim 1 or 8, characterized by, The charging time according to the first current is T1, and the charging time according to the second current is T2, wherein T1 / T2 is greater than or equal to 5.

15. The charging method according to claim 1, wherein, The battery is a lithium ion battery.

16. The charging method according to claim 1, wherein The capacity of the battery is greater than or equal to 50 AH.

17. The charging method according to claim 1, wherein A ratio of a current value of the second current to a current value of the first current is M, the M is in a negative correlation with at least one of the battery tab parameter and the temperature of the battery, wherein the parameter of the battery tab includes at least one of the conductivity, the area density, the compacted density and the thickness of the battery tab.

18. The charging method according to claim 17, wherein, A ratio of a current value of the second current to a current value of the first current is M, a variation range of the negative correlation of the M with the parameter of the negative electrode tab of the battery is greater than a variation range of the negative correlation of the M with the parameter of the positive electrode tab of the battery.

19. The charging method according to claim 1, characterized by, A charging time length according to the first current is less than or equal to a charging cutoff time length, the charging cutoff time length is a charging time length when the battery voltage reaches a battery cutoff voltage when the battery is charged according to the first current.

20. The charging method according to claim 1 or 19, characterized by, The charging time length according to the first current is less than or equal to 250s.

21. An electronic device, comprising: The electronic device includes a memory configured to store a computer program and a processor, the processor implements the charging method of any one of claims 1-20 when executing the computer program.

22. A charging device, characterized by The charging device is configured to charge the battery according to the first current and the second current in sequence, wherein the current value of the second current is less than the current value of the first current, the charging time length according to the first current is greater than or equal to 30s, the first current is greater than 1C, and the current value of the second current is greater than 0.

23. A battery management system, comprising: The battery management system includes the electronic device of claim 21 or the charging device of claim 22.

24. An electrical device, comprising: The use device includes the battery, the charging device of claim 22 or the battery management system of claim 23.

25. A computer-readable storage medium, characterized in that, The computer readable storage medium stores a computer program, when the computer program is executed by one or more processors, the charging method of any one of claims 1-20 is implemented.

26. A computer program product comprising computer programs / instructions, characterized in that, The computer program / instruction is executed by the processor to implement the method of any one of claims 1-20.

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