Charging method and charging device for battery

Abstract

The present invention provides a charging method and charging device for a battery. The charging method comprises the following steps: (1) on the basis of charging time T and a preset first mapping table, determining an average charging rate Ca, an initial charging rate C1, and a termination charging rate CT; on the basis of the preset number n of battery cycles, determining charging time t and a rate increase amplitude I of a single charging rate; and (2) on the basis of the initial charging rate C1, the termination charging rate CT, and the charging time t and the rate increase amplitude I of the single charging rate, determining a charging combination scheme. According to the present invention, the charging rate and the cycle performance of a lithium metal battery are analyzed, and a set of combined charging method is designed and screened, thereby implementing the lithium metal battery having both high-rate charging performance and cycle performance.

Description

Battery charging method and charging device

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application with application number 202310871688.X filed with the China Patent Office on July 14, 2023, entitled “A Battery Charging Method and Charging Device”. The entire contents of the above application are incorporated by reference into this application. Technical Field

[0003] The present invention belongs to the technical field of battery charging, and relates to a battery charging method and a charging device. Background Art

[0004] Lithium metal as the negative electrode, combined with a high-energy-density positive electrode material, can significantly improve the energy density of lithium-ion secondary batteries. Lithium metal batteries have a high energy density, but their cycle performance and cycle safety are still far behind those of conventional lithium-ion batteries. This is mainly because lithium ions are deposited and stripped on the lithium metal surface many times during the charging and discharging process of lithium metal batteries, which easily forms dead lithium and dendrites, thereby significantly reducing the cycle life and safety of the battery cell. At present, most lithium metal batteries achieve long cycle performance by using low-rate charging methods through strategies such as negative electrode surface protection and electrolyte modification. However, lithium metal batteries that have both high-rate charging capabilities and long cycle performance have not yet been reported.

[0005] Summary of the Invention

[0006] To address the inability of lithium metal batteries to maintain excellent cycle performance at high charge rates, the present invention provides a battery charging method and device. By analyzing the charge rate and cycle performance of lithium metal batteries, the present invention designs and screens a combined charging method to achieve a lithium metal battery that combines high-rate charge performance with excellent cycle performance.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for charging a battery, the method comprising the following steps:

[0009] (1) Determine the average charging rate C based on the charging time T and the preset first mapping table a , initial charge rate C1 and final charge rate C T ; Based on the preset number of battery cycles n, determine the charging time t and rate increase I of a single charging rate;

[0010] (2) Based on the initial charge rate C1 and the final charge rate C T, the charging time t and rate increase I of a single charging rate, and determine the charging combination plan.

[0011] As a preferred embodiment of the present invention, the average charging rate C in step (1) a =1 / T.

[0012] As a preferred embodiment of the present invention, the charging time is 0.2h≤T≤5h.

[0013] As a preferred solution of the present invention, the first mapping table in step (1) is used to record the empirical correspondence between the preset charging time and the initial charging rate.

[0014] As a preferred embodiment of the present invention, the termination charge rate C in step (1) T According to formula C T =2C a -C1 is calculated.

[0015] As a preferred embodiment of the present invention, the charging time of a single charging rate in step (1) is Multiplier increase Wherein β is a correction factor, 100≤β≤1000 and is an integer, and β=0 during the first charge.

[0016] As a preferred embodiment of the present invention, in step (1), n≥100.

[0017] As a preferred embodiment of the present invention, the charging combination scheme in step (2) includes a combination of 2n+β+1 charging rates, wherein the charging time of a single charging rate is t.

[0018] As a preferred embodiment of the present invention, the charging combination scheme in step (2) includes: after charging at an initial charging rate C1, charging at the remaining 2n+β charging rates is performed in ascending order, where β is a correction factor, 100≤β≤1000 and is an integer, and β=0 during the first charging.

[0019] As a preferred embodiment of the present invention, the charging combination scheme in step (2) includes: when the state of charge (SOC) of the battery is 0%, charging at the initial charging rate C1 for t hours, then jumping to charging at the rate of C1+k*I for t hours, and repeating in sequence until jumping 2n+β times, that is, charging at C1+k*I for t hours. T The battery is charged at a charging rate of t hours; where k is the number of jumps.

[0020] As a preferred embodiment of the present invention, when charging at a single charging rate in step (2), a charging cut-off voltage protection is set.

[0021] As a preferred solution of the present invention, the cutoff condition of the charging cutoff voltage protection is: when the battery charging voltage reaches 4.3V, the current rate charging process is terminated and the next rate charging is performed.

[0022] As a preferred embodiment of the present invention, the charging method further includes the following steps: (3) verifying the charging combination scheme, and when the charging combination scheme needs to be modified after verification, modifying the charging combination scheme, and continuing to verify after modification until the charging combination scheme meets the judgment criteria.

[0023] As a preferred embodiment of the present invention, the verification in step (3) includes: performing a cycle test on the battery according to the charging combination scheme, and determining the actual number of cycles n at which the battery capacity retention rate decays to 80%. r , based on the preset battery cycle number n and the actual cycle number n r The difference verifies the charging combination solution.

[0024] As a preferred embodiment of the present invention, when nn r When ≤25, the charging combination solution meets the preset requirements.

[0025] As a preferred embodiment of the present invention, when 25<nn r When ≤50, the charging time t and rate increase I of a single charging rate need to be corrected;

[0026] As a preferred embodiment of the present invention, when 50<nn r When the battery is fully charged, the initial charging rate C1 needs to be corrected.

[0027] As a preferred embodiment of the present invention, when 25<nn r When ≤50, the correction factor β is introduced to correct the charging time t and rate increase I of a single charging rate, that is, Multiplier increase 100≤β≤1000 and is an integer, and the value of β increases with the increase of the number of corrections.

[0028] As a preferred embodiment of the present invention, when 50<nn r When the correction factor α is introduced to the initial charging rate C1 and the termination rate C T And the rate increase I is modified, 0.5≤α<1, and the new initial rate C 1+m =α*C1, where m represents the number of corrections, and the value of α decreases as the number of corrections increases.

[0029] In a second aspect, the present invention provides a charging device, comprising:

[0030] Charging time input module, used to input preset charging time T;

[0031] The charging rate acquisition module is used to determine the average charging rate C according to the charging time T and the preset first mapping table. a , initial charge rate C1 and final charge rate C T ;

[0032] A cycle number input module is used to input a preset battery cycle number n;

[0033] The charging time and rate increase acquisition module of a single charging rate is used to obtain the battery cycle number n, charging time T, initial charging rate C1 and termination charging rate C according to the preset battery cycle number n, charging time T, initial charging rate C1 and termination charging rate C T Determine the charging time t and rate increase I for a single charging rate;

[0034] A charging combination plan determination module, used to generate a charging combination plan;

[0035] The charging module is used to charge the battery according to the charging combination scheme.

[0036] As a preferred embodiment of the present invention, the charging device further includes:

[0037] A verification and determination module is used to verify the charging result to determine whether the charging combination plan needs to be revised;

[0038] The correction module is used to correct the charging combination plan based on the verification and judgment result.

[0039] As a preferred solution of the present invention, the correction module includes: a correction factor α input module for inputting the value of α; an initial charging rate C1, a termination rate C2, and a correction factor α input module for inputting the value of α; T And the rate increase I correction module is used to adjust the initial charging rate C1 and the termination rate C according to the input correction factor α. T and the rate increase I for correction; a correction factor β input module, used for inputting the β value; a single charging rate charging time t and rate increase I correction module, used for correcting the charging time t and rate increase I of a single charging rate according to the input correction factor β; an output module, used for outputting a charging combination plan that meets the preset performance after correction.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] The present invention designs and screens a set of combined charging methods by analyzing the charging rate and cycle performance of lithium metal batteries, which can charge the lithium metal batteries at a rate of 0.2C or above while ensuring the cycle performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] FIG1 is a flow chart of a charging method according to an example embodiment of the present invention;

[0043] FIG2 is a flow chart of a charging method according to an example embodiment of the present invention;

[0044] FIG3 is a schematic diagram of a charging device according to an example embodiment of the present invention. DETAILED DESCRIPTION

[0045] To better illustrate the present invention and facilitate understanding of the technical solution of the present invention, the present invention is further described in detail below. However, the following embodiments are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0046] The specific embodiment of the present invention provides a method for charging a battery, the charging method comprising the following steps:

[0047] (1) Determine the average charging rate C based on the charging time T and the preset first mapping table a , initial charge rate C1 and final charge rate C T ; Based on the preset number of battery cycles n, determine the charging time t and rate increase I of a single charging rate;

[0048] (2) Based on the initial charge rate C1 and the final charge rate C T , the charging time t and rate increase I of a single charging rate, and determine the charging combination plan.

[0049] In the present invention, the rate increase I refers to the difference between two adjacent charging rates.

[0050] In the present invention, The unit of t in the formula is hours.

[0051] There is a specific mapping relationship between the initial charging rate and the preset charging time. The initial charging rate corresponding to the preset charging time not in the first mapping table can be selected from the first mapping table as the initial charging rate of the preset charging time.

[0052] In the present invention, the battery can be a lithium metal battery system, in which the negative electrode is lithium metal or lithium alloy, wherein the lithium alloy includes but is not limited to Li-M, wherein the M element includes any one of Zn, C, Ag, Al, K, Mg, Pb, Si, Sn, Ge, Sb or Bi, or a combination of at least two thereof.

[0053] The present invention does not limit the lithium metal battery and its preparation method. Known industrial battery cell preparation methods can be used, such as stacking or winding the negative electrode, separator and positive electrode in sequence into a battery cell, and then encapsulating it in an aluminum-plastic film, injecting liquid, forming and re-sealing it to produce a lithium metal battery.

[0054] As a preferred solution of the present invention, the average charging rate C in step (1) a =1 / T.

[0055] As a preferred solution of the present invention, the charging time 0.2h≤T≤5h, for example, 0.2h, 0.5h, 1h, 2h, 3h, 4h or 5h, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0056] As a preferred solution of the present invention, the first mapping table in step (1) is used to record the empirical correspondence between the preset charging time and the initial charging rate.

[0057] As a preferred solution of the present invention, the termination charge rate C in step (1) T According to formula C T =2C a -C1 is calculated.

[0058] As a preferred solution of the present invention, the charging time of a single charging rate in step (1) is Multiplier increase Wherein β is a correction factor, 100≤β≤1000 and is an integer, such as 100, 200, 300, 400, 500, 600, 700, 800, 900, or 1000, etc., but is not limited to the listed values. Other values ​​not listed in this numerical range are also applicable. During the first charge, β=0. In the present invention, since no correction factor is introduced during the first charge, β=0 during the first charge.

[0059] As a preferred embodiment of the present invention, in step (1), n≥100, for example, 100, 200, 300, 400, 500, 600, 700, 800, 900 or 1000, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0060] As a preferred solution of the present invention, the charging combination solution in step (2) includes a combination of 2n+β+1 charging rates, wherein the charging time of a single charging rate is t.

[0061] As a preferred solution of the present invention, the charging combination solution in step (2) includes: after charging at an initial charging rate C1, charging at the remaining 2n+β charging rates is performed in ascending order, where β is a correction factor, 100≤β≤1000 and is an integer, such as 100, 200, 300, 400, 500, 600, 700, 800, 900 or 1000, etc., but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable. β=0 during the first charge.

[0062] As a preferred solution of the present invention, the charging combination solution in step (2) includes: when the state of charge (SOC) of the battery is 0%, charging at the initial charging rate C1 for t hours, then jumping to charging at the rate of C1+k*I for t hours, and repeating in sequence until jumping 2n+β times, that is, charging at C1+k*I for t hours. T The battery is charged at a charging rate of t hours; where k is the number of jumps.

[0063] As a preferred solution of the present invention, when charging at a single charging rate in step (2), a charging cut-off voltage protection is set.

[0064] As a preferred solution of the present invention, the cutoff condition of the charging cutoff voltage protection is: when the battery charging voltage reaches 4.3V, the current rate charging process is terminated and the next rate charging is performed.

[0065] As a preferred solution of the present invention, the charging method further includes the following steps: (3) verifying the charging combination scheme, and when the charging combination scheme needs to be modified after verification, modifying the charging combination scheme, and continuing to verify after modification until the charging combination scheme meets the judgment criteria.

[0066] In the present invention, for lithium metal batteries, the verification refers to charge and discharge cycle verification of the lithium metal batteries.

[0067] As a preferred solution of the present invention, the verification in step (3) includes: performing a cycle test on the battery according to the charging combination scheme, and determining the actual number of cycles n at which the battery capacity retention rate decays to 80%. r , based on the preset battery cycle number n and the actual cycle number n r The difference verifies the charging combination solution.

[0068] As a preferred embodiment of the present invention, when nn r When ≤25 (e.g., 25, 23, 20, 17, 15, 13, 10, or -5, but not limited to the listed values, other values ​​not listed in the range are also applicable), the charging combination solution meets the preset requirements;

[0069] When 25<nn r When ≤50 (e.g., 27, 30, 35, 40, 45, or 50, but not limited to the listed values, other values ​​not listed in this range are also applicable), the charging time t and rate increase I of a single charging rate need to be corrected;

[0070] When 50<nn r When the initial charging rate C1 is less than 53, 55, 60, 65, 70, 75, 80 or 85, etc., but not limited to the listed values, other values ​​not listed in the numerical range are also applicable), the initial charging rate C1 needs to be corrected.

[0071] As a preferred solution of the present invention, when 25<nn r When ≤50, the correction factor β is introduced to correct the charging time t and rate increase I of a single charging rate, that is, Multiplier increase 100≤β≤1000 and is an integer, and the value of β increases with the increase of the number of corrections.

[0072] In the present invention, the value of β is referenced to nn r The size of the value, the larger the difference, the larger the value, which is mainly based on experience.

[0073] In the present invention, the preset charging conditions can be met by selecting an appropriate correction factor β. Within the value range of β, any combined charging method formed under the condition that the value of β is greater than or equal to β can meet the preset charging conditions.

[0074] As a preferred solution of the present invention, when 50<nn r When the correction factor α is introduced to the initial charging rate C1 and the termination rate C T And the rate increase I is modified, 0.5≤α<1, and the new initial rate C 1+m =α*C1, where m represents the number of corrections, and the value of α decreases as the number of corrections increases.

[0075] In the present invention, the value of α is referenced to nn r The size of the value, the larger the difference, the smaller the value, which is mainly based on experience.

[0076] In the present invention, when a suitable correction factor α is selected, the preset charging condition can be met. Within the value range of α, any combined charging method formed under the condition that the value is less than or equal to α can meet the preset charging condition.

[0077] More specifically, the charging method of the present invention, as shown in FIG1 , includes:

[0078] (1) Determine the average charging rate C based on the charging time T and the preset first mapping table a , initial charge rate C1 and final charge rate C T ; Based on the preset number of battery cycles n, determine the charging time t and rate increase I of a single charging rate;

[0079] (2) Based on the initial charge rate C1 and the final charge rate C T , the charging time t and rate increase I of a single charging rate, and determine the charging combination plan;

[0080] (3) Verify the charging combination plan. After verification, if the conditions are met, charging is completed. If the charging requirements are not met, the charging combination plan needs to be revised. After the revision, verification is continued until the charging combination plan meets the judgment criteria.

[0081] Furthermore, the charging method of the present invention, as shown in FIG2 , includes:

[0082] (1) Determine the average charging rate C based on the charging time T and the preset first mapping table a , initial charge rate C1 and final charge rate C T , where C a =1 / T, 0.2h≤T≤5h, C1 is determined based on the preset first mapping table, C T =2C a -C1; Based on the preset number of battery cycles n, determine the charging time t and rate increase I of a single charging rate, where the charging time of a single charging rate is Multiplier increase Where β is the correction factor, 100≤β≤1000 and is an integer. When charging for the first time, β=0, and n≥100;

[0083] (2) Based on the initial charge rate C1 and the final charge rate C T , the charging time t and the rate increase I of a single charging rate, determining a charging combination scheme, the charging combination scheme comprising: charging at an initial charging rate C1, and then charging at the remaining 2n+β charging rates in ascending order, where β is a correction factor, 100≤β≤1000 and is an integer, and β=0 for the first charging;

[0084] (3) Verify the charging combination scheme. After verification, if the conditions are met, charging is completed. If the charging requirements are not met, the charging combination scheme needs to be revised. After the revision, verification is continued until the charging combination scheme meets the judgment criteria. The verification includes: performing a cycle test on the battery according to the charging combination scheme, and determining the actual number of cycles n at which the battery capacity retention rate decays to 80%. r, based on the preset battery cycle number n and the actual cycle number n r The difference verifies the charging combination scheme;

[0085] When nn r When ≤25, the charging combination solution meets the preset requirements;

[0086] When 25<nn r When ≤50, the correction factor β is introduced to correct the charging time t and rate increase I of a single charging rate, that is, Multiplier increase 100≤β≤1000 and is an integer, and the value of β increases with the increase of the number of corrections;

[0087] When 50<nn r When the correction factor α is introduced to the initial charging rate C1 and the termination rate C T And the rate increase I is modified, 0.5≤α<1, and the new initial rate C 1+m =α*C1, where m represents the number of corrections, and the value of α decreases as the number of corrections increases.

[0088] The specific embodiment of the present invention further provides a charging device, which includes:

[0089] Charging time input module, used to input preset charging time T;

[0090] The charging rate acquisition module is used to determine the average charging rate C according to the charging time T and the preset first mapping table. a , initial charge rate C1 and final charge rate C T ;

[0091] A cycle number input module is used to input a preset battery cycle number n;

[0092] The charging time and rate increase acquisition module of a single charging rate is used to obtain the battery cycle number n, charging time T, initial charging rate C1 and termination charging rate C according to the preset battery cycle number n, charging time T, initial charging rate C1 and termination charging rate C T Determine the charging time t and rate increase I for a single charging rate;

[0093] A charging combination plan determination module, used to generate a charging combination plan;

[0094] The charging module is used to charge the battery according to the charging combination scheme.

[0095] As a preferred solution of the present invention, the charging device further includes:

[0096] A verification and determination module is used to verify the charging result to determine whether the charging combination plan needs to be revised;

[0097] The correction module is used to correct the charging combination plan based on the verification and judgment result.

[0098] As a preferred solution of the present invention, the correction module includes: a correction factor α input module for inputting the value of α; an initial charging rate C1, a termination rate C2, and a correction factor α input module for inputting the value of α; T And the rate increase I correction module is used to adjust the initial charging rate C1 and the termination rate C according to the input correction factor α. T and the rate increase I for correction; a correction factor β input module, used for inputting the β value; a single charging rate charging time t and rate increase I correction module, used for correcting the charging time t and rate increase I of a single charging rate according to the input correction factor β; an output module, used for outputting a charging combination plan that meets the preset performance after correction.

[0099] In the present invention, after the output module outputs the revised charging combination scheme and charging is performed in the charging module, the correction module continues to verify the charging combination scheme until the charging combination scheme meets the judgment standard.

[0100] More specifically, the charging device of the present invention, as shown in FIG3 , includes:

[0101] Charging time input module, used to input preset charging time T;

[0102] The charging rate acquisition module is used to determine the average charging rate C according to the charging time T and the preset first mapping table. a , initial charge rate C1 and final charge rate C T ;

[0103] A cycle number input module is used to input a preset battery cycle number n;

[0104] The charging time and rate increase acquisition module of a single charging rate is used to obtain the battery cycle number n, charging time T, initial charging rate C1 and termination charging rate C according to the preset battery cycle number n, charging time T, initial charging rate C1 and termination charging rate C T Determine the charging time t and rate increase I for a single charging rate;

[0105] A charging combination plan determination module, used to generate a charging combination plan;

[0106] The charging module is used to charge the battery according to the charging combination scheme.

[0107] Charging time input module, used to input preset charging time T;

[0108] The charging rate acquisition module is used to determine the average charging rate C according to the charging time T and the preset first mapping table. a, initial charge rate C1 and final charge rate C T ;

[0109] A cycle number input module is used to input a preset battery cycle number n;

[0110] The charging time and rate increase acquisition module of a single charging rate is used to obtain the battery cycle number n, charging time T, initial charging rate C1 and termination charging rate C according to the preset battery cycle number n, charging time T, initial charging rate C1 and termination charging rate C T Determine the charging time t and rate increase I for a single charging rate;

[0111] A charging combination plan determination module, used to generate a charging combination plan;

[0112] A charging module, used to charge the battery according to a charging combination scheme;

[0113] A verification and determination module is used to verify the charging result to determine whether the charging combination plan needs to be revised;

[0114] The correction module is used to correct the charging combination plan based on the verification and judgment result.

[0115] The following are typical but non-limiting examples of the present invention:

[0116] Example 1:

[0117] This embodiment provides a method for preparing a lithium metal battery, the method comprising:

[0118] (1) Preparation of positive electrode sheet: LiNi 0.8 Co 0.1 Mn 0.1 O2, polyvinylidene fluoride (PVDF), and carbon black (CB) were dissolved in N-methylpyrrolidone at a mass ratio of 98:1:1 to prepare a slurry with a solid content of 70%. The slurry was applied to aluminum foil, dried at 85°C, and then cold-pressed and cut into 86mm x 66mm pieces to produce the positive electrode sheets.

[0119] (2) Preparation of negative electrode sheets: Lithium-copper composite strips (10 μm copper foil covered with 50 μm lithium foil on both sides) were cut into 88 mm*68 mm negative electrode sheets.

[0120] (3) Preparation of electrolyte: A 1 M lithium hexafluorophosphate mixed solution of ethylene carbonate (EC) / ethyl methyl carbonate (EMC) was prepared in a dry argon atmosphere, with the mass ratio of EC to EMC in the mixed solution being 1:1.

[0121] (4) Preparation of lithium metal batteries: A polyethylene separator with a thickness of 20 microns is selected, and the negative electrode, separator and positive electrode are stacked in order. The stacked battery cell structure is fixed with tape and placed in an aluminum-plastic film. After top and side sealing, liquid injection, packaging, formation and secondary sealing, a lithium metal battery is finally obtained.

[0122] The following Examples 2-5 and Comparative Examples 1-4 were all charged and verified using the lithium metal battery prepared in Example 1. Since the single rate charging time in the examples presented is relatively short, the single rate charging time t is expressed in seconds for ease of presentation.

[0123] Example 2:

[0124] This embodiment provides a combined charging method for a lithium metal battery, the method comprising:

[0125] (1) The preset charging time of the lithium metal battery is T = 2.5h, and the preset number of cycles with a discharge rate of 1C is n = 400 times. The average charging rate C can be obtained by the preset charging time T. a =0.4, based on the average charge rate C a =0.4 and the first mapping table (Table 1), the initial charging rate C1=0.1 is obtained, according to the formula C T =2C a -C1 calculates the termination ratio C T =0.7. According to the preset number of cycles n and The single rate charging time t=11.25s (without correction, the first β value is 0) and the adjacent rate increase I=0.00075 can be obtained.

[0126] (2) According to the initial magnification C a , termination ratio C T , a single rate charging time t and an adjacent rate increase I, forming a combined charging method, the specific steps of the charging method are: when the lithium metal battery is at SOC = 0%, it is charged at a constant current rate of C1 = 0.1, the charging time is t = 11.25s, and immediately after the charging of this stage is completed, it jumps to a constant current rate of C1 + k*I (k = 1, I = 0.00075) for charging, the charging time is t = 11.25s, and so on, until the jump 2n + β (n = 400, no correction is introduced for the first time, β = 0) times, the lithium metal battery is charged at C T =0.7 times constant current charging, charging time is t = 11.25s. In order to improve the charging safety of lithium metal batteries, a charging voltage protection process is set during the single rate charging process. Specifically: during the single rate charging process, when the charging voltage of the lithium metal battery is greater than 4.3V, the current charging process is immediately terminated and the next rate charging process is jumped.

[0127] (3) Perform a cycle test of the above combined charging method on the lithium metal battery, and the discharge rate is consistent with the preset discharge rate. Obtain the number of cycles n of the current combined charging method r =394. r Make a judgment, which meets nn r ≤25, the combined charging method obtained above is suitable for the current charging performance requirements of lithium metal batteries.

[0128] Table 1: First mapping table

[0129] Example 3:

[0130] This embodiment provides a combined charging method for a lithium metal battery, the method comprising:

[0131] (1) The preset charging time of the lithium metal battery is T = 1.25h, and the preset number of cycles with a discharge rate of 1C is n = 300 times. The average charging rate C can be obtained by the preset charging time T. a =0.8, based on the average charge rate C a =0.8 and the first mapping table (Table 1), the initial charging rate C1=0.3 is obtained, according to the formula C T =2C a -C1 calculates the termination ratio C T =1.3. According to the preset number of cycles n and The single rate charging time t=7.5s (without correction, the first β value is 0) and the adjacent rate increase I=0.00167 can be obtained.

[0132] (2) According to the initial magnification C a , termination ratio C T , a single rate charging time t and an adjacent rate increase I are used to form a combined charging method. The specific steps of the charging method are as follows: when the lithium metal battery is at SOC = 0%, it is charged at a constant current rate of C1 = 0.3 for a charging time of t = 7.5s. After the charging of this stage is completed, it is immediately jumped to a constant current charging rate of C1 + k*I (k = 1, I = 0.00167) for a charging time of t = 7.5s, and so on, until the jump is 2n + β (n = 300, no correction is introduced for the first time, β = 0) times, the lithium metal battery is charged at C T =1.3 times constant current charging, charging time is t = 7.5s. In order to improve the charging safety of lithium metal batteries, a charging voltage protection process is set during the single rate charging process. Specifically: during the single rate charging process, when the charging voltage of the lithium metal battery is greater than 4.3V, the current charging process is immediately terminated and the next rate charging process is jumped.

[0133] (3) Perform a cycle test of the above combined charging method on the lithium metal battery, and the discharge rate is consistent with the preset discharge rate. Obtain the number of cycles n of the current combined charging method r =273. r Make a judgment, it does not meet nn r ≤25, the above combined charging method needs to be modified. r ≤50, a correction factor β is needed to correct the single rate charging time t and the increase I between adjacent rates. The first correction β value is 100, according to the formula The calculation results show that t = 6.43s and I = 0.00143. Based on the corrected single rate charging time t and the increase I between adjacent rates, the corrected combined charging method is obtained. The lithium metal battery is cycled using the above combined charging method, and the discharge rate is consistent with the preset discharge rate. The number of cycles n of the current combined charging method is obtained. r =286. By r Make a judgment, which meets nn r ≤25, then the above-mentioned revised combined charging method is adapted to the current charging performance requirements of lithium metal batteries.

[0134] Example 4:

[0135] This embodiment provides a combined charging method for a lithium metal battery, the method comprising:

[0136] (1) The preset charging time of the lithium metal battery is T = 1h, and the preset number of cycles with a discharge rate of 1C is n = 250 times. The average charge rate C can be obtained by the preset charging time. a =1, based on the average charging rate C a =1 and the first mapping table (Table 1), obtain the initial charging rate C1 = 0.4, according to the formula C T =2C a -C1 calculates the termination ratio C T =1.6. According to the preset number of cycles n and The single rate charging time t=7.2s (without correction, the first β value is 0) and the adjacent rate increment I=0.0024 can be obtained.

[0137] (2) According to the initial magnification C a , termination ratio C T, a single rate charging time t and an adjacent rate increase I, forming a combined charging method, the specific steps of the charging method are: when the lithium metal battery is at SOC = 0%, it is charged at a constant current rate of C1 = 0.4, the charging time is t = 7.2s, and immediately after the charging of this stage is completed, it jumps to a constant current rate of C1 + k*I (k = 1, I = 0.0024) for charging, the charging time is t = 7.2s, and so on, until the jump 2n + β (n = 250, no correction is introduced for the first time, β = 0) times, the lithium metal battery is charged at C T =1.6 times constant current charging, charging time is t = 7.2s. In order to improve the charging safety of lithium metal batteries, a charging voltage protection process is set during the single rate charging process. Specifically: during the single rate charging process, when the charging voltage of the lithium metal battery is greater than 4.3V, the current charging process is immediately terminated and the next rate charging process is jumped.

[0138] (3) Perform a cycle test of the above combined charging method on the lithium metal battery, and the discharge rate is consistent with the preset discharge rate. Obtain the number of cycles n of the current combined charging method r =203. r Make a judgment, it does not meet nn r ≤25, the above combined charging method needs to be modified. r ≤50, a correction factor β is needed to correct the single rate charging time t and the increase I between adjacent rates. The first correction β value is 100, according to the formula The calculation results show that t = 6s and I = 0.002. Based on the corrected single rate charging time t and the increase I between adjacent rates, the corrected combined charging method is obtained. The lithium metal battery is cycled using the above combined charging method, and the discharge rate is consistent with the preset discharge rate. The number of cycles n of the current combined charging method is obtained. r =223. By nn r Make a judgment, it still does not meet nn r ≤25, the above combined charging method needs to be revised again. r =223 is still far from the preset discharge rate cycle number n, so the value of the correction factor β can be appropriately increased, such as β is 300. According to the formula The calculation results show that t = 4.5s and I = 0.0015. Based on the second-corrected single rate charging time t and the increase I between adjacent rates, the corrected combined charging method is obtained. The lithium metal battery is cycled using the above combined charging method, and the discharge rate is consistent with the preset discharge rate. The number of cycles n of the current combined charging method is obtained. r=237. r Make a judgment, which meets nn r ≤25, then the above-mentioned revised combined charging method is adapted to the current charging performance requirements of lithium metal batteries.

[0139] Example 5:

[0140] This embodiment provides a combined charging method for a lithium metal battery, the method comprising:

[0141] (1) The preset charging time of the lithium metal battery is T = 0.715h, and the preset number of cycles with a discharge rate of 1C is n = 200 times. The average charge rate C can be obtained by the preset charging time. a =1.4, based on the average charge rate C a =1.4 and the first mapping table (Table 1), the initial charging rate C1=0.7 is obtained, according to the formula C T =2C a -C1 calculates the termination ratio C T =2.1. According to the preset number of cycles n and The single rate charging time t=6.435s (without correction, the first β value is 0) and the adjacent rate increase I=0.0035 can be obtained.

[0142] (2) According to the initial magnification C a , termination ratio C T , a single rate charging time t and an adjacent rate increase I, forming a combined charging method, the specific steps of the charging method are: when the lithium metal battery is at SOC = 0%, it is charged at a constant current rate of C1 = 0.7, the charging time is t = 6.435s, and immediately after the charging of this stage is completed, it jumps to a constant current rate of C1 + k*I (k = 1, I = 0.0035) for charging, the charging time is t = 6.435s, and so on, until the jump 2n + β (n = 250, no correction is introduced for the first time, β = 0) times, the lithium metal battery is charged at C T =2.1 times constant current charging, charging time is t = 6.435s. In order to improve the charging safety of lithium metal batteries, a charging voltage protection process is set during the single rate charging process. Specifically: during the single rate charging process, when the charging voltage of the lithium metal battery is greater than 4.3V, the current charging process is immediately terminated and the next rate charging process is jumped.

[0143] (3) Perform a cycle test of the above combined charging method on the lithium metal battery, and the discharge rate is consistent with the preset discharge rate. Obtain the number of cycles n of the current combined charging method r =123. By r Make a judgment, it does not meet nnr ≤25, the above combined charging method needs to be modified. r , it is necessary to introduce a correction factor α to adjust the initial charging rate C1 and the termination rate C T As the actual number of cycles of the combined charging method mentioned above is quite different from the preset number of cycles of the discharge rate, a smaller value is selected within the range of α. α = 0.8 is selected for the first time, and the corrected initial charge rate C1 = 0.56 and the termination rate C T =2.24 and the increase I = 0.0042. According to the corrected initial charge rate C 1、 C T The above charging method is verified on lithium metal to obtain the number of cycles n of the current combined charging method. r =157. r Make a judgment, it still does not meet nn r ≤25, the above combined charging method needs to be revised again. r <50, it is necessary to correct the single rate charging time t and the increase I between adjacent rates. Since the actual number of cycles of the above combined charging method is quite different from the preset discharge rate cycle number, a larger value is selected within the range of β. The corrected β value is 400, according to the formula The calculation results show that t = 3.22s and I = 0.0021. Based on the corrected single rate charging time t and the increase I between adjacent rates, the corrected combined charging method is obtained. The lithium metal battery is cycled using the above combined charging method, and the discharge rate is consistent with the preset discharge rate. The number of cycles n of the current combined charging method is obtained. r =179. r Make a judgment, which meets nn r ≤25, then the above-mentioned revised combined charging method is adapted to the current charging performance requirements of lithium metal batteries.

[0144] Comparative Example 1:

[0145] This comparative example provides a charging method for a lithium metal battery, wherein the preset charging time and the cycle performance at a specific discharge rate are consistent with those of Example 2. The charging method is conventional constant rate charging, specifically, C a = 0.4 times the rate of charging, the charging time is T = 2.5h. At the same time, in order to improve the charging safety of lithium metal batteries, a charging voltage protection process is set during the charging process, specifically: a= 0.4 rate charging process, when the charging voltage of the lithium metal battery is greater than 4.3V, the charging is stopped immediately and jumps to the discharge process. The lithium metal battery is cycled tested with the above charging method, and the discharge rate is consistent with the preset discharge rate. Get the number of cycles n of the current combined charging method r =198.

[0146] Comparative Example 2:

[0147] This comparative example provides a charging method for a lithium metal battery, and its preset charging time and cycle performance under a specific discharge rate are consistent with those of Example 3. The charging method is conventional constant rate charging, specifically at C a = 0.8 times the rate of charging, the charging time is T = 1.25h. At the same time, in order to improve the charging safety of lithium metal batteries, a charging voltage protection process is set during the charging process, specifically: a = 0.8 rate charging process, when the charging voltage of the lithium metal battery is greater than 4.3V, the charging is stopped immediately and jumps to the discharge process. The lithium metal battery is cycled tested with the above charging method, and the discharge rate is consistent with the preset discharge rate. Get the number of cycles n of the current combined charging method r =146.

[0148] Comparative Example 3:

[0149] This comparative example provides a charging method for a lithium metal battery, and its preset charging time and cycle performance at a specific discharge rate are consistent with those of Example 4. The charging method is conventional constant rate charging, specifically at C a = 1, and the charging time is T = 1h. At the same time, in order to improve the charging safety of lithium metal batteries, a charging voltage protection process is set during the charging process at this rate, specifically: a = 1, when the charging voltage of the lithium metal battery is greater than 4.3V, the charging is stopped immediately and the process is switched to the discharge process. The lithium metal battery is subjected to the above charging method cycle test, and the discharge rate is consistent with the preset discharge rate. Get the number of cycles n of the current combined charging method r =89.

[0150] Comparative Example 4:

[0151] This comparative example provides a charging method for a lithium metal battery, and its preset charging time and cycle performance under a specific discharge rate are consistent with those of Example 5. The charging method is conventional constant rate charging, specifically at C a =1.4 times, and the charging time is T=0.715h. At the same time, in order to improve the charging safety of the lithium metal battery, a charging voltage protection process is set during the charging process at this rate, specifically:a =1.4 rate charging process, when the charging voltage of the lithium metal battery is greater than 4.3V, the charging is stopped immediately and jumps to the discharge process. The lithium metal battery is cycled tested with the above charging method, and the discharge rate is consistent with the preset discharge rate. Get the number of cycles n of the current combined charging method r =46.

[0152] The cycle performance test results of the lithium metal batteries in Examples 2-5 and Comparative Examples 1-4 are shown in Table 2.

[0153] Table 2 Test results of Examples 2-5 and Comparative Examples 1-4

[0154] As can be seen from Table 2, by introducing the combined charging method, lithium metal batteries can maintain excellent cycle performance at higher charging rates. Compared with conventional constant current charging, the number of cycles of lithium metal batteries is greatly improved.

[0155] The applicant declares that the present invention uses the above-described embodiments to illustrate the detailed process equipment and process flow of the present invention. However, the present invention is not limited to the above-described detailed process equipment and process flow, and does not necessarily rely on the above-described detailed process equipment and process flow in order to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent replacements for the raw materials of the present invention's products, additions of auxiliary ingredients, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A battery charging method, characterized in that: The charging method comprises the following steps: (1) Determine the average charging rate C based on the charging time T and the preset first mapping table a , initial charge rate C1 and final charge rate C T ; Based on the preset number of battery cycles n, determine the charging time t and rate increase I of a single charging rate; (2) Based on the initial charging rate C1 and the final charging rate C T , the charging time t of a single charging rate and the rate increase I, and determine the charging combination plan.

2. The charging method according to claim 1, characterized in that: The average charging rate C in step (1) a =1 / T; Preferably, the charging time is 0.2h≤T≤5h; Preferably, the first mapping table in step (1) is used to record the empirical correspondence between the preset charging time T and the initial charging rate C1; Preferably, the termination charge rate C in step (1) is T According to formula C T =2C a -C1 is calculated.

3. The charging method according to claim 1, characterized in that: Charging time for a single charging rate in step (1) Multiplier Where β is the correction factor, 100≤β≤1000 and is an integer, and β=0 for the first charge; Preferably, in step (1), n≥100.

4. The charging method according to claim 1, characterized in that: The charging combination scheme in step (2) includes a combination of 2n+β+1 charging rates, wherein the charging time of a single charging rate is t; Preferably, the charging combination scheme in step (2) includes: after charging at an initial charging rate C1, the remaining 2n+β charging rates are charged in ascending order, where β is a correction factor, 100≤β≤1000 and is an integer, and β=0 for the first charging; Preferably, the charging combination scheme in step (2) includes: when the battery state of charge is 0%, charging at an initial charging rate C1 for t hours, then jumping to charging at a rate of C1+k*I for t hours, and repeating in sequence until jumping 2n+β times, that is, charging at C1+k*I for 2 hours. T Charge at a charging rate of t hours; where k is the number of jumps.

5. The charging method according to claim 4, characterized in that: When charging at a single charging rate in step (2), setting a charging cut-off voltage protection; Preferably, the cut-off condition of the charging cut-off voltage protection is: when the battery charging voltage reaches 4.3V, the charging process of the current rate is terminated, and the charging process of the next rate is jumped.

6. The charging method according to claim 1, characterized in that: The charging method further comprises the following steps: (3) verifying the charging combination scheme, and when the charging combination scheme needs to be modified after verification, modifying the charging combination scheme, and continuing to verify after modification until the charging combination scheme meets the determination criteria; Preferably, the verification in step (3) includes: performing a cycle test on the battery according to the charging combination scheme to determine the The actual number of cycles n at which the cell capacity retention rate decays to 80% r , based on the preset battery cycle number n and the actual cycle number n r The difference verifies the charging combination scheme; When nn r When ≤25, the charging combination solution meets the preset requirements; When 25<nn r When ≤50, the charging time t and rate increase I of a single charging rate need to be corrected; When 50<nn r When the battery is charged, the initial charging rate C1 needs to be corrected.

7. The charging method according to claim 6, characterized in that: When 25<nn r When ≤50, the correction factor β is introduced to correct the charging time t and rate increase I of a single charging rate, that is, Multiplier 100≤β≤1000 and is an integer, and the value of β increases with the number of corrections; Preferably, when 50 < nn r When the correction factor α is introduced, the initial charging rate C1 and the termination rate C T And the multiplier I is modified, 0.5≤α<1, and the new initial multiplier C 1+m =α*C1, where m represents the number of corrections, and the value of α decreases as the number of corrections increases.

8. A charging device, characterized in that: The charging device comprises: A charging time input module, used to input a preset charging time T; The charging rate acquisition module is used to determine the average charging rate C according to the charging time T and the preset first mapping table. a , initial charge rate C1 and final charge rate C T ; A cycle number input module is used to input a preset battery cycle number n; The charging time and rate increase acquisition module of a single charging rate is used to obtain the battery cycle number n, charging time T, initial charging rate C1 and termination charging rate C according to the preset battery cycle number n, charging time T, initial charging rate C1 and termination charging rate C T Determine the charging time t and rate increase I of a single charging rate; A charging combination scheme determination module, used for generating a charging combination scheme; The charging module is used to charge the battery according to the charging combination scheme.

9. The charging device according to claim 8, characterized in that: The charging device also includes: A verification and determination module is used to verify the charging result to determine whether the charging combination plan needs to be modified; The correction module is used to correct the charging combination plan based on the verification and determination result.

10. The charging device according to claim 9, characterized in that: The correction module includes: a correction factor α input module, which is used to input the value of α; an initial magnification C1, a termination magnification C T and a rate increase correction module I, which is used to adjust the initial charging rate C1 and the termination rate C according to the input correction factor α. T and rate increase I for correction; a correction factor β input module, used for inputting the β value; a single charging rate charging time t and rate increase I correction module, used for correcting the charging time t and rate increase I of a single charging rate according to the input correction factor β; an output module, used for outputting a charging combination plan that meets the preset performance after correction.

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