CN114035066A - A Lithium Battery Consistency Evaluation Method - Google Patents

Abstract

Translated fromChinese

本发明公开了一种锂电池一致性评价方法，属于锂电池技术领域，包括获取分容后电池的常规信息；对分容电池进行放充电处理，并基于电池常规信息，对电池进行预分档，得到预分档电池组；将预分档电池组在低温环境中静置设定时长后放电，测量并计算电池的第一电压信息、直流内阻及第一电压差；将预分档电池组在高温环境中静置不同时长，测量并计算电池的第二电压信息和第二电压差；依据每个电池的第一电压信息、第一电压差、直流内阻、第二电压信息和第二电压差，对所述电池进行档位内的二次分档。本发明将动态及静态测试相结合，能更有效反映电池的一致性特性。

The invention discloses a lithium battery consistency evaluation method, which belongs to the technical field of lithium batteries. , obtain a pre-graded battery pack; discharge the pre-graded battery pack after standing in a low temperature environment for a set period of time, measure and calculate the first voltage information, DC internal resistance and first voltage difference of the battery; The group is left standing in a high temperature environment for different periods of time, and the second voltage information and second voltage difference of the battery are measured and calculated; according to the first voltage information, first voltage difference, DC internal resistance, second voltage information and The second voltage difference is used to carry out the secondary classification of the battery in the gear. The present invention combines dynamic and static tests, which can more effectively reflect the consistency characteristics of the battery.

Description

Lithium battery consistency evaluation method

Technical Field

The invention relates to the technical field of lithium batteries, in particular to a lithium battery consistency evaluation method.

Background

In recent years, lithium ion batteries have been greatly developed in the fields of power batteries and energy storage, but also face great safety problems, one of the main factors is the inconsistency of battery production. In a power battery and energy storage use scene, batteries need to be assembled for use, and when the batteries have differences, the batteries cannot exert complete performance due to the barrel effect, and are easy to generate overcharge and overdischarge phenomena to cause safety accidents.

Disclosure of Invention

The invention aims to provide a lithium battery consistency evaluation method and system, aiming at ensuring that a grouped battery has good consistency in a wide temperature range.

In order to achieve the above object, the present invention provides a lithium battery consistency evaluation method, including:

obtaining conventional information of the battery after capacity grading, wherein the conventional information comprises capacity grading capacity, discharge median voltage, alternating current internal resistance, battery weight and battery thickness;

carrying out discharge and charge processing on the capacity-grading batteries, and pre-grading the batteries based on conventional information of the batteries to obtain a pre-grading battery pack;

discharging the pre-grading battery pack after standing for a set time in a low-temperature environment, and measuring and calculating first voltage information, direct current internal resistance and a first voltage difference of the battery;

standing the pre-grading battery pack in a high-temperature environment for different durations, and measuring and calculating second voltage information and a second voltage difference of the battery;

and performing secondary grading in the gears on the batteries according to the first voltage information, the first voltage difference, the direct current internal resistance, the second voltage information and the second voltage difference of each battery.

Further, the discharging and charging processing of the capacity-classified battery and the pre-grading of the battery based on the conventional information of the battery to obtain the pre-graded battery pack include:

performing discharge and charge processing on the capacity-divided battery to obtain voltage information;

and pre-grading the battery based on the voltage information and the conventional information of the battery to obtain a pre-graded battery pack.

Further, the performing discharge and charge processing on the capacity-divided battery to obtain voltage information includes:

applying a current I to the battery₁Discharging at constant current until cut-off voltage and then using current I₂Continuously discharging the battery to a no-load state;

charging the battery to a cut-off voltage corresponding to the target SOC in a constant current and constant voltage mode;

after the battery is stood at normal temperature for different time lengths, calculating the voltage difference delta V of the battery₁＝V₁-V₂Wherein V is₁For the battery to stand at normal temperature for a time t₂Voltage of the cell, V₂For the standing time t of the pool at normal temperature₁The voltage of the battery.

Further, the pre-grading the battery based on the voltage information and the battery general information to obtain a pre-graded battery pack includes:

the voltage V is based on the conventional information of the battery according to the set grading standard₁Said voltage V₂And said voltage difference Δ V₁And pre-grading the battery to obtain a pre-graded battery pack.

Further, the step of discharging the pre-staged battery pack after standing the pre-staged battery pack for a set time period in a low-temperature environment, and measuring and calculating first voltage information, direct current internal resistance and a first voltage difference of the battery comprises:

pre-staging battery pack at low temperature T₀Time t of environmental standing₁Post-applied current I₃Discharge t₃And time length, calculating first voltage information, direct current internal resistance and first voltage difference of the battery, wherein the first voltage information comprises the time length t of the battery standing in the low-temperature environment₁Time cell voltage V₃And current I₃Discharge t₃Terminal voltage V of the battery over time₄The direct current internal resistance R₀＝(V₃-V₄)/t₃Said first voltage difference Δ V₂＝V₃-V₂。

Further, the step of allowing the pre-grading battery pack to stand in a high-temperature environment for different durations, and measuring and calculating second voltage information and a second voltage difference of the battery includes:

placing the pre-staged battery pack at a high temperature T₁Standing time t in environment₁After standing for a period of time t₄Measuring the temperature T of the battery at high temperature₁Standing time t in environment₁Voltage V of time₄And said cell is at high temperature T₁Standing time t in environment₄Voltage V of time₅；

According to voltage V₄And voltage V₅And calculating to obtain the second voltage difference DeltaV₃Wherein Δ V₃＝V₄-V₅。

Further, the temperature T₀The value range is [ -20 ℃, 0 DEG C]。

Further, the temperature T1 has a value range of [40 ℃, 55 ℃ ].

Further, the time duration t1 is in a range of [6h, 24h ], and the time duration t2 is in a range of [12h, 72h ].

Further, the time duration t3 is in a range of [10s, 60s ], and the time duration t4 is in a range of [12h, 48h ].

Compared with the prior art, the invention has the following technical effects: the invention combines dynamic and static tests, and can more effectively reflect the consistency characteristic of the battery; and according to the characteristics of the lithium battery, the pertinence test of a wide temperature range is carried out, and the consistency characteristics of the battery under different use scenes can be more comprehensively evaluated. The invention can ensure the consistency of the initial state of the battery and the consistency of the battery in the later use process as much as possible, and finally achieves the purpose of improving the consistency of the full life cycle of the battery.

Drawings

The following detailed description of embodiments of the invention refers to the accompanying drawings in which:

FIG. 1 is a flow chart of a lithium battery consistency evaluation method of the present invention.

Detailed Description

To further illustrate the features of the present invention, refer to the following detailed description of the invention and the accompanying drawings. The drawings are for reference and illustration purposes only and are not intended to limit the scope of the present disclosure.

As shown in fig. 1, the present embodiment discloses a lithium battery consistency evaluation method, which includes the following steps S10 to S50:

s10: obtaining conventional information of the battery after capacity grading, wherein the conventional information comprises capacity grading capacity, discharge median voltage, alternating current internal resistance, battery weight and battery thickness;

s20: carrying out discharge and charge processing on the capacity-grading batteries, and pre-grading the batteries based on conventional information of the batteries to obtain a pre-grading battery pack;

s30: discharging the pre-grading battery pack after standing for a set time in a low-temperature environment, and measuring and calculating first voltage information, direct current internal resistance and a first voltage difference of the battery;

s40: standing the pre-grading battery pack in a high-temperature environment for different durations, and measuring and calculating second voltage information and a second voltage difference of the battery;

s50: and performing secondary grading in the gears on the batteries according to the first voltage information, the first voltage difference, the direct current internal resistance, the second voltage information and the second voltage difference of each battery.

As a more preferable technical solution, in step S20: the method comprises the following steps of carrying out discharge and charge processing on a capacity grading battery, and pre-grading the battery based on conventional information of the battery to obtain a pre-graded battery pack, wherein the method comprises the following steps:

s21: performing discharge and charge processing on the capacity-divided battery to obtain voltage information;

s22: and pre-grading the battery based on the voltage information and the conventional information of the battery to obtain a pre-graded battery pack.

As a more preferable technical solution, in step S21: the method for carrying out discharge and charge processing on the capacity-divided battery to obtain voltage information comprises the following steps:

applying a current I to the battery₁Discharging at constant current until cut-off voltage and then using current I₂Continuously discharging the battery to a no-load state;

charging the battery to a cut-off voltage corresponding to the target SOC in a constant current and constant voltage mode;

after the battery is stood at normal temperature for different time lengths, calculating the voltage difference delta V of the battery₁＝V₁-V₂Wherein V is₁For the battery to stand at normal temperature for a time t₂Voltage of the cell, V₂For the standing time t of the pool at normal temperature₁The voltage of the battery.

As a more preferable technical solution, in step S22: pre-grading the battery based on the voltage information and the conventional information of the battery to obtain a pre-graded battery pack, comprising:

the voltage V is based on the conventional information of the battery according to the set grading standard₁Said voltage V₂And said voltage difference Δ V₁And pre-grading the battery to obtain a pre-graded battery pack.

As an example, the pre-binning criteria may be based on voltage V₁Voltage difference Δ V₁The statistical distribution is determined so as to determine,

such as voltage V₁Is given by

Within a range and a voltage difference DeltaV₁Is at a value of V₂±d₂Model (A) of

The batteries in the enclosure are selected as the same gear. The above-mentioned

For all batteries V₁Average value of (1)

D is described₁The tolerance value is set according to actual conditions; the above-mentioned

For all cells Δ V₁Average value of (d) the₂Is a tolerance value set according to actual conditions.

As a more preferable technical solution, in step S30: the method comprises the following steps of discharging a pre-grading battery pack after standing for a set time in a low-temperature environment, measuring and calculating first voltage information, direct-current internal resistance and first voltage difference of a battery, and comprises the following steps:

pre-staging battery pack at low temperature T₀Time t of environmental standing₁Post-applied current I₃Discharge t₃Calculating first voltage information, direct current internal resistance and first voltage difference of the battery according to the duration, wherein the first voltage information comprises the electricityThe standing time of the pool in a low-temperature environment is t₁Time cell voltage V₃And current I₃Discharge t₃Terminal voltage V of the battery over time₄The direct current internal resistance R₀＝(V₃-V₄)/t₃Said first voltage difference Δ V₂＝V₃-V₂。

As a more preferable technical solution, in step S40: the method comprises the following steps of standing the pre-grading battery pack in a high-temperature environment for different durations, measuring and calculating second voltage information and a second voltage difference of a battery, and comprises the following steps:

placing the pre-staged battery pack at a high temperature T₁Standing time t in environment₁After standing for a period of time t₄Measuring the temperature T of the battery at high temperature₁Standing time t in environment₁Voltage V of time₄And said cell is at high temperature T₁Standing time t in environment₄Voltage V of time₅；

According to voltage V₄And voltage V₅And calculating to obtain the second voltage difference DeltaV₃Wherein Δ V₃＝V₄-V₅。

As a further preferred solution, said temperature T is₀The value range is [ -20 ℃, 0 DEG C](ii) a The temperature T1 is in the range of 40 ℃ and 55 DEG C]。

As a further preferred technical solution, the time length t1 ranges from [6h, 24h ], the time length t2 ranges from [12h, 72h ], the time length t3 ranges from [10s, 60s ], and the time length t4 ranges from [12h, 48h ].

As a more preferable technical solution, in step S50: and performing secondary grading in the gears on the pre-graded batteries according to the first voltage information, the first voltage difference, the direct current internal resistance, the second voltage information and the second voltage difference of each battery. The further grading standard may also be determined according to statistical distribution of the first voltage, the first voltage difference, the direct current internal resistance, the second voltage and the second voltage difference of each battery, for example, batteries of which the first voltage, the first voltage difference, the direct current internal resistance, the second voltage and the second voltage difference are within corresponding tolerance ranges are selected as the same grade.

It should be noted that, the grading standard is determined according to production and manufacturing big data, in this embodiment, a parameter statistically distributed within a set deviation range is set as a first grade, and the parameters distributed outside the deviation range are eliminated.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (10)

Translated fromChinese

1.一种锂电池一致性评价方法，其特征在于，包括：1. a lithium battery consistency evaluation method, is characterized in that, comprises:获取分容后电池的常规信息，所述常规信息包括分容容量、放电中值电压、交流内阻、电池重量及电池厚度；Acquiring general information of the battery after capacity division, the general information including capacity division, median discharge voltage, AC internal resistance, battery weight and battery thickness;对分容电池进行放充电处理，并基于电池常规信息，对电池进行预分档，得到预分档电池组；Discharging and charging the battery with different capacity, and pre-binning the battery based on the general information of the battery to obtain a pre-binning battery pack;将预分档电池组在低温环境中静置设定时长后放电，测量并计算电池的第一电压信息、直流内阻及第一电压差；Discharge the pre-graded battery pack after standing in a low temperature environment for a set period of time, and measure and calculate the first voltage information, DC internal resistance and first voltage difference of the battery;将预分档电池组在高温环境中静置不同时长，测量并计算电池的第二电压信息和第二电压差；The pre-graded battery pack is placed in a high temperature environment for different time periods, and the second voltage information and the second voltage difference of the battery are measured and calculated;依据每个电池的第一电压信息、第一电压差、直流内阻、第二电压信息和第二电压差，对所述电池进行档位内的二次分档。According to the first voltage information, the first voltage difference, the DC internal resistance, the second voltage information and the second voltage difference of each battery, the battery is subjected to secondary classification within the gear.2.如权利要求1所述的锂电池一致性评价方法，其特征在于，所述对分容电池进行放充电处理，并基于电池常规信息，对电池进行预分档，得到预分档电池组，包括：2. The method for evaluating the consistency of lithium batteries according to claim 1, wherein the discharging and charging process is performed on the capacity-separating batteries, and based on the conventional information of the batteries, the batteries are pre-ranked to obtain a pre-ranking battery pack ,include:对所述分容电池进行放充电处理，得到电压信息；Performing discharge and charging processing on the divided-capacity battery to obtain voltage information;基于电压信息和所述电池常规信息，对所述电池进行预分档，得到预分档电池组。Based on the voltage information and the battery general information, the batteries are pre-rated to obtain a pre-rated battery pack.3.如权利要求2所述的锂电池一致性评价方法，其特征在于，所述对所述分容电池进行放充电处理，得到电压信息，包括：3. The method for evaluating the consistency of lithium batteries according to claim 2, wherein the discharging and charging process is performed on the split-capacity battery to obtain voltage information, comprising:将所述电池以电流I₁恒流放电至截止电压后以电流I₂对电池进行继续放电至空电状态；The battery is continuously discharged to the cut-off voltage with the current I₁ to the cut-off voltage, and then the battery is continuously discharged to the empty state with the current I₂ ;以恒流恒压方式将电池充电至目标SOC对应的截止电压；Charge the battery to the cut-off voltage corresponding to the target SOC by means of constant current and constant voltage;将所述电池常温静置不同时长后，计算所述电池的电压差ΔV₁＝V₁-V₂，其中，V₁为所述电池常温静置时长t₂时电池的电压，V₂为池常温静置时长t₁时电池的电压。After the battery is left standing at room temperature for different periods of time, calculate the voltage difference of the battery ΔV₁ =V₁ -V₂ , where V₁ is the voltage of the battery when the battery is left standing at room temperature for a length of t₂ , and V₂ is the battery voltage The voltage of the battery when it is left at room temperature for a length of_t1 .4.如权利要求3所述的锂电池一致性评价方法，其特征在于，所述基于电压信息和所述电池常规信息，对所述电池进行预分档，得到预分档电池组，包括：4. The lithium battery consistency evaluation method according to claim 3, wherein the battery is pre-classified based on the voltage information and the battery conventional information to obtain a pre-classified battery pack, comprising:根据设定的分档标准，基于所述电池的常规信息、所述电压V₁、所述电压V₂和所述电压差ΔV₁，对所述电池进行预分档，得到预分档电池组。According to the set classification standard, based on the general information of the battery, the voltage V₁ , the voltage V₂ and the voltage difference ΔV₁ , the battery is pre-classified to obtain a pre-classified battery pack .5.如权利要求1所述的锂电池一致性评价方法，其特征在于，所述将预分档电池组在低温环境中静置设定时长后放电，测量并计算电池的第一电压信息、直流内阻及第一电压差，包括：5. The method for evaluating the consistency of lithium batteries according to claim 1, wherein the pre-graded battery pack is discharged after standing in a low temperature environment for a set period of time, and the first voltage information of the battery is measured and calculated. DC internal resistance and first voltage difference, including:将所述预分档电池组在低温T₀环境静置时长t₁后以电流I₃放电t₃时长，计算所述电池的第一电压信息、直流内阻及第一电压差，其中，所述第一电压信息包括所述电池在低温环境静置时长t₁时电池电压V₃和电流I₃放电t₃时长时所述电池的末端电压V₄，所述直流内阻R₀＝(V₃-V₄)/t₃，所述第一电压差ΔV₂＝V₃-V₂。After the pre-graded battery pack is placed in a low temperature T₀ environment for a period of t₁ and discharged with a current I₃ for a period of t₃ , the first voltage information, the DC internal resistance and the first voltage difference of the battery are calculated, wherein, the The first voltage information includes the battery voltage V₃ when the battery is in a low temperature environment for a period of t₁ and the terminal voltage V₄ of the battery when the current I₃ is discharged for a period of t₃ , the DC internal resistance R₀ =(V₃ -V₄ )/t₃ , the first voltage difference ΔV₂ =V₃ -V₂ .6.如权利要求5所述的锂电池一致性评价方法，其特征在于，所述将预分档电池组在高温环境中静置不同时长，测量并计算电池的第二电压信息和第二电压差，包括：6. The method for evaluating the consistency of lithium batteries according to claim 5, wherein the pre-graded battery packs are allowed to stand in a high temperature environment for different periods of time, and the second voltage information and the second voltage of the battery are measured and calculated. poor, including:将所述预分档电池组在高温T₁环境中静置时长t₁后在静置时长t₄，测量所述电池在高温T₁环境中静置时长t₁时的电压V₄，以及所述电池在高温T₁环境中静置时长t₄时的电压V₅；The pre-graded battery pack is placed in a high temperature T1 environment for a period of time t₁ and then for a period of t₄ , and the voltage V₄ of the battery when the battery is placed in a high temperature T₁ environment for_{a period of time t 1is} measured, and all voltage V₅ when the battery is left standing in a high temperature T₁ environment for a length of time t₄ ;根据电压V₄和电压V₅，计算得到所述第二电压差ΔV₃，其中ΔV₃＝V₄-V₅。According to the voltage V₄ and the voltage V₅ , the second voltage difference ΔV₃ is obtained by calculation, where ΔV₃ =V₄ −V₅ .7.如权利要求5所述的锂电池一致性评价方法，其特征在于，所述温度T₀取值范围为[-20℃，0℃]。7 . The method for evaluating the consistency of lithium batteries according to claim 5 , wherein the temperature T₀ has a value range of [-20° C., 0° C.]. 8 .8.如权利要求6所述的锂电池一致性评价方法，其特征在于，所述温度T1取值范围为[40℃，55℃]。8 . The method for evaluating the consistency of lithium batteries according to claim 6 , wherein the temperature T1 ranges from [40° C., 55° C.]. 9 .9.如权利要求3所述的锂电池一致性评价方法，其特征在于，所述时长t1取值范围为[6h，24h]，所述时长t2取值范围为[12h，72h]。9 . The lithium battery consistency evaluation method according to claim 3 , wherein the value range of the duration t1 is [6h, 24h], and the value range of the duration t2 is [12h, 72h]. 10 .10.如权利要求6所述的锂电池一致性评价方法，其特征在于，所述时长t3取值范围为[10s，60s]，所述时长t4取值范围为[12h，48h]。10 . The lithium battery consistency evaluation method according to claim 6 , wherein the value range of the duration t3 is [10s, 60s], and the value range of the duration t4 is [12h, 48h]. 11 .

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