Method, system and device for predicting calendar life of batteries with different SOC

Abstract

The present invention discloses a method, system, and device for predicting the calendar life of batteries with different SOCs, including the following steps: selecting a reference group of cells with a preset SOC; testing the calendar life of the reference group of cells at a preset temperature and a first preset time according to a calendar life testing method and recording the data; performing linear or polynomial fitting based on the recorded calendar life data of the reference group of cells at the corresponding time to derive calendar life data within a second preset time, where the second preset time is the time range after the first preset time; and calculating calendar life data for other SOCs different from the preset SOC using a first-order kinetic reaction formula. This solution significantly reduces calendar life testing time and can obtain calendar life data for different SOCs with smaller intervals without requiring extensive testing of a large number of cells with different SOCs.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and in particular to a method, system and device for predicting the calendar life of batteries with different SOCs. Background Art

[0002] The existing method for collecting calendar life at different states of charge (SOC) mainly involves grouping battery cells into different SOC steps and performing state of health (SOH) checks at fixed intervals. The current calendar life prediction method mainly uses data from some battery cells at a certain temperature under a fixed SOC to predict the calendar life at this temperature condition and other temperature conditions under the fixed state of charge using a simplified equation of the Arrhenius equation. Among them, the method of grouping battery cells into different SOC steps and performing SOH checks at fixed intervals requires a large amount of battery cell investment, consumes a lot of manpower, and cannot take into account the calendar life over the entire SOC range. Summary of the Invention

[0003] In response to the above technical problems, the present invention proposes a method for predicting the calendar life of a battery with different SOCs.

[0004] The scheme provides a method for predicting the calendar life of a battery at different SOCs, including the following steps:

[0005] Select the baseline battery pack with preset SOC;

[0006] Performing calendar life testing of the reference group battery cells at a preset temperature and a first preset time according to a calendar life testing method and recording data;

[0007] Performing linear or polynomial fitting based on the recorded calendar life data of the reference group battery cells at the corresponding time to derive calendar life data within a second preset time, where the second preset time is a time range after the first preset time;

[0008] The calendar life data of other SOCs different from the preset SOC is calculated using the first-order kinetic reaction formula.

[0009] Wherein, the first-order kinetic reaction is: Where k is the reaction rate constant, t is the reaction time, a is the initial concentration of the reactant, and ax is the concentration of the reactant at time t.

[0010] Using the SOC data as k, the time corresponding to the calendar life as t, and the calendar life of the battery cell at the corresponding time as ax, calculate the calendar life data of other SOCs different from the preset SOC.

[0011] Optionally, the preset SOC of the reference group battery cells is selected as any value in the range of 1%-100%.

[0012] Optionally, the first preset time range is 1 year to 15 years.

[0013] Optionally, the preset temperature range is -30°C-60°C.

[0014] Optionally, the fitting method includes: linear fitting or polynomial fitting.

[0015] Optionally, the calculated SOC interval is greater than 0.1%.

[0016] Furthermore, based on the above technical problems, the present invention proposes a battery life prediction system with different SOC calendars, including the following structure:

[0017] A test data input unit is configured to receive calendar life data obtained by testing a reference group of battery cells at a preset temperature and a first preset time according to a calendar life test method, including calendar life and corresponding time; wherein the reference group of battery cells is a selected reference group of battery cells having a preset SOC;

[0018] a data fitting unit, configured to perform linear or polynomial fitting based on the recorded calendar life data of the reference group battery cells at the corresponding time, to derive calendar life data within a second preset time, where the second preset time is a time range after the first preset time;

[0019] The calendar life prediction unit is used to calculate the calendar life data of other SOCs different from the preset SOC using a first-order kinetic reaction formula.

[0020] Furthermore, the present invention proposes a battery calendar life prediction device based on the above technical problems, the device comprising: a memory and a processor;

[0021] The memory is used to store program instructions;

[0022] The processor is used to call the program instructions stored in the memory to implement the battery different SOC calendar life prediction method.

[0023] Beneficial effects of the present invention:

[0024] This method selects a battery cell from a specific SOC group for calendar life testing, collecting calendar life data under that SOC. Data fitting can then be used to obtain longer-term calendar life data under that SOC. Based on the principle that the primary factor affecting calendar life under different SOC conditions is the extent of side reactions determined by the content of active lithium in the negative electrode, the method utilizes first-order chemical kinetic reaction conditions to accurately predict calendar life under other SOCs. This method reduces calendar life testing time and allows for obtaining calendar life data at smaller intervals without requiring extensive testing of a large number of battery cells at different SOCs, resulting in simpler and more accurate data products and services. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 This is a flow chart of the battery calendar life prediction method for different SOCs. DETAILED DESCRIPTION

[0027] Unless otherwise defined, technical or scientific terms used in this application shall have the ordinary meanings understood by those skilled in the art. The terms "first," "second," "third," "fourth," and similar words used in this specification and claims do not denote any order, quantity, or importance, but are simply used to distinguish different components.

[0028] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application. In the following description, reference is made to the drawings that form a part of this application and illustrate specific aspects of the embodiments of the present application or specific aspects of the embodiments of the present application that can be used. It should be understood that the embodiments of the present application can be used in other aspects and may include structural or logical changes not depicted in the drawings. Therefore, the following detailed description should not be understood in a restrictive sense, and the scope of the present application is defined by the appended claims. In addition, it should also be understood that, unless otherwise expressly stated, the features of the various exemplary embodiments and / or aspects described herein can be combined with each other.

[0029] Example 1:

[0030] A method for predicting the calendar life of batteries at different SOCs, such as Figure 1 , including the following steps:

[0031] Step (1), selecting a reference group of cells with a preset SOC;

[0032] Step (2), performing calendar life testing of the reference group battery cells at a preset temperature and a first preset time according to a calendar life testing method and recording data;

[0033] Step (3), fitting the calendar life data of the reference group battery cells at the corresponding time recorded, and deriving the calendar life data within a second preset time, where the second preset time is a time range after the first preset time;

[0034] Step (4) uses a first-order kinetic reaction formula to calculate calendar life data of other SOCs different from the preset SOC.

[0035] Specifically, the first-order kinetic reaction is represented by formula (1):

[0036]

[0037] Where k is the reaction rate constant, t is the reaction time, a is the initial concentration of the reactant, and ax is the concentration of the reactant at time t.

[0038] In this solution, the SOC data is used as k, the time corresponding to the calendar life is used as t, and the calendar life of the battery cell at the corresponding time is used as ax to calculate the calendar life data of other SOCs different from the preset SOC.

[0039] Some cases are presented below to further illustrate this solution:

[0040] Option 1: Set the SOC to 100% and the temperature to 25°C. The first preset interval is one year, with a monthly measurement frequency for calendar life data (hereinafter referred to as "SOH"). The second preset interval is three years, and the calendar life data at 50% SOC is calculated. All of these data are adjustable.

[0041] A method for predicting calendar life of a battery at different SOCs comprises the following steps:

[0042] Step (1), selecting 100% SOC of the battery cell as the reference group battery cell, and charging the battery cell sample to be tested to 100% SOC state;

[0043] Step (2) The reference group battery cells are tested for one year of calendar life at 25°C according to the calendar life test method and data is collected. The SOH inspection frequency is once a month. The collected data is as shown in the following table;

[0044] 1 2 3 4 5 6 7 8 9 10 11 12 99.22％ 98.89％ 98.46％ 95.61％ 96.78％ 96.50％ 95.78％ 96.79％ 95.31％ 96.35％ 96.08％ 95.36％

[0045] Step (3) performs binomial fitting on the data collected in step (2) to derive three-year calendar life data. The binomial formula is y = 0.0004x 2 -0.0087x+0.996, where x is the number of months and y is the SOH. The three-year calendar life data is derived as follows:

[0046] 1 2 3 4 5 6 7 8 9 10 11 12 99.22％ 98.89％ 98.46％ 95.61％ 96.78％ 96.50％ 95.78％ 96.79％ 95.31％ 96.35％ 96.08％ 95.36％ 13 14 15 16 17 18 19 20 21 22 23 24 95.71％ 95.38％ 95.05％ 94.72％ 94.39％ 94.06％ 93.73％ 93.40％ 93.07％ 92.74％ 92.41％ 92.08％ 25 26 27 28 29 30 31 32 33 34 35 36 91.75％ 91.42％ 91.09％ 90.76％ 90.43％ 90.10％ 89.77％ 89.44％ 89.11％ 88.78％ 88.45％ 88.12％

[0047] Step (4) uses the first-order kinetic reaction formula The calendar life data of step (3) is calculated for the calendar life data of 50% SOC. Wherein, k is the side reaction rate that affects the calendar life, which is linearly related to the amount of lithium inserted into the negative electrode. The amount of lithium inserted into the negative electrode can be numerically simplified to SOC+(1-battery first effect), where the battery first effect is the known value of the battery leaving the factory, t is the number of months of reaction, a is the initial SOH, and for the initial new battery cell, a=100%, ax is the SOH after the reaction for t months, and the calculation method is as follows: Formula (2):

[0048]

[0049] In this case, given the 100% SOC baseline battery cell data (t months, which is divided by the t value in the ratio formula), the k value, the initial SOH, the SOH at t months, and the time t at 50% SOC, the k value, and the initial SOH, we can calculate the SOH at 50% SOC at t months by making a ratio between the 100% SOC state and the 50% SOC state.

[0050] The calculation results of calendar life data for 50% SOC are as follows:

[0051] 1 2 3 4 5 6 7 8 9 10 11 12 99.58％ 99.41％ 99.18％ 97.64％ 98.27％ 98.12％ 97.73％ 98.28％ 97.48％ 98.04％ 97.89％ 97.50％ 13 14 15 16 17 18 19 20 21 22 23 24 97.69％ 97.51％ 97.33％ 97.15％ 96.97％ 96.79％ 96.61％ 96.43％ 96.25％ 96.06％ 95.88％ 95.70％ 25 26 27 28 29 30 31 32 33 34 35 36 95.52％ 95.33％ 95.15％ 94.97％ 94.78％ 94.60％ 94.41％ 94.23％ 94.04％ 93.86％ 93.67％ 93.48％

[0052] Option 2: Preset SOC to 100%; preset temperature to 25°C; first preset time is one year, with calendar life data measured monthly; second preset time is three years, with calendar life data calculated at 30% SOC. All of the above data are adjustable.

[0053] Step (1) Selecting 100% SOC of a cell as a reference group cell, and charging the cell sample to be tested to 100% SOC state;

[0054] Step (2) The reference group battery cells are tested for one year of calendar life at 25°C according to the calendar life test method and data is collected. The SOH inspection frequency is once a month. The collected data is as shown in the following table;

[0055] 1 2 3 4 5 6 7 8 9 10 11 12 99.22％ 98.89％ 98.46％ 95.61％ 96.78％ 96.50％ 95.78％ 96.79％ 95.31％ 96.35％ 96.08％ 95.36％

[0056] Step (3) performs binomial fitting on the data collected in step (2) to derive three-year calendar life data. The binomial formula is y = 0.0004x 2 -0.0087x+0.996, where x is the number of months and y is the SOH. The three-year calendar life data is derived as follows:

[0057] 1 2 3 4 5 6 7 8 9 10 11 12 99.22％ 98.89％ 98.46％ 95.61％ 96.78％ 96.50％ 95.78％ 96.79％ 95.31％ 96.35％ 96.08％ 95.36％ 13 14 15 16 17 18 19 20 21 22 23 24 95.71％ 95.38％ 95.05％ 94.72％ 94.39％ 94.06％ 93.73％ 93.40％ 93.07％ 92.74％ 92.41％ 92.08％ 25 26 27 28 29 30 31 32 33 34 35 36 91.75％ 91.42％ 91.09％ 90.76％ 90.43％ 90.10％ 89.77％ 89.44％ 89.11％ 88.78％ 88.45％ 88.12％

[0058] Step (4) uses the first-order kinetic reaction formula The calendar life data of step (3) is calculated. According to formula (1) and formula (2) and the above-mentioned method, the calendar life data of 30% SOC is compared with the calendar life data of 100% SOC state and the SOH of 30% SOC in response to t months is calculated.

[0059] The calculation results of calendar life data for 30% SOC are as follows:

[0060] 1 2 3 4 5 6 7 8 9 10 11 12 99.73％ 99.61％ 99.47％ 98.46％ 98.87％ 98.78％ 98.52％ 98.88％ 98.35％ 98.72％ 98.63％ 98.37％ 13 14 15 16 17 18 19 20 21 22 23 24 98.50％ 98.38％ 98.26％ 98.14％ 98.02％ 97.90％ 97.79％ 97.67％ 97.55％ 97.43％ 97.31％ 97.19％ 25 26 27 28 29 30 31 32 33 34 35 36 97.07％ 96.95％ 96.82％ 96.70％ 96.58％ 96.46％ 96.34％ 96.21％ 96.09％ 95.97％ 95.84％ 95.72％

[0061] Option 3: The preset SOC is 100%; the preset temperature is 45°C; the first preset time is one year, and the frequency of measuring calendar life data is once a month; the second preset time is three years; the above data are all adjustable data.

[0062] A method for predicting calendar life of a battery at different SOCs comprises the following steps:

[0063] Step (1) Selecting 100% SOC of a cell as a reference group cell, and charging the cell sample to be tested to 100% SOC state;

[0064] Step (2) The reference group battery cells are tested for one year of calendar life at 45°C according to the calendar life test method and data is collected. The SOH inspection frequency is once a month. The collected data is as shown in the following table;

[0065] 1 2 3 4 5 6 7 8 9 10 11 12 99.32％ 95.52％ 96.04％ 93.19％ 95.01％ 93.42％ 93.04％ 91.93％ 92.10％ 91.21％ 91.08％ 91.40％

[0066] Step (3) performs binomial fitting on the data collected in step (2) to derive three-year calendar life data. The binomial formula is y = 0.0006x 2 -0.0141x+0.996, where x is the number of months and y is the SOH, the three-year calendar life data is derived as follows:

[0067] 1 2 3 4 5 6 7 8 9 10 11 12 99.32％ 95.52％ 96.04％ 93.19％ 95.01％ 93.42％ 93.04％ 91.93％ 92.10％ 91.21％ 91.08％ 91.40％ 13 14 15 16 17 18 19 20 21 22 23 24 92.20％ 91.60％ 91.00％ 90.40％ 89.80％ 89.20％ 88.60％ 88.00％ 87.40％ 86.80％ 86.20％ 85.60％ 25 26 27 28 29 30 31 32 33 34 35 36 85.00％ 84.40％ 83.80％ 83.20％ 82.60％ 82.00％ 81.40％ 80.80％ 80.20％ 79.60％ 79.00％ 78.40％

[0068] 4) Using the first-order kinetic reaction formula The calendar life data of step (3) is calculated for the calendar life data of 50% SOC. According to formula (1) and formula (2) and the above-mentioned method, the calendar life data of 100% SOC state is compared with the calendar life data of 50% SOC state to calculate the SOH of 30% SOC in reaction t months.

[0069] The calculation results of calendar life data of 50% SOC at 45℃ are as follows:

[0070] 1 2 3 4 5 6 7 8 9 10 11 12 99.68％ 99.36％ 99.04％ 98.71％ 98.39％ 98.07％ 97.74％ 97.41％ 97.09％ 96.76％ 96.43％ 96.10％ 13 14 15 16 17 18 19 20 21 22 23 24 95.77％ 95.43％ 95.10％ 94.77％ 94.43％ 94.09％ 93.76％ 93.42％ 93.08％ 92.74％ 92.39％ 92.05％ 25 26 27 28 29 30 31 32 33 34 35 36 91.71％ 91.36％ 91.01％ 90.67％ 90.32％ 89.97％ 89.62％ 89.26％ 88.91％ 88.56％ 88.20％ 87.84％

[0071] Among them, binomial fitting can use data processing software such as Origin and SPSS without restriction.

[0072] It should be noted that although the above case only discloses 100% SOC as the reference group battery cell, the preset SOC of the reference group battery cell can be any value in the range of 1%-100%.

[0073] Although the above case discloses only a first preset time range of one year, any value within the range of one to fifteen years is acceptable. Similarly, the actual calculation of the second preset time can be any number of years greater than the first preset time, generally taking into account the battery lifespan. It should be noted that the second preset time disclosed in this embodiment is after the first preset time, for example, one year after the first preset time, one year and six months, two years, three years, etc. In the above case, the data for the first preset time is measured data, while the binomial calculation is based on the data from the first month of the year to the third year.

[0074] The above case discloses data testing under 25℃ and 45℃ conditions. In actual work, the preset temperature range is -30℃-60℃, which can be selected according to needs.

[0075] As an optional item, the fitting method includes linear fitting or polynomial fitting, which can generally be selected according to actual accuracy requirements.

[0076] As an option, the calculated SOC interval is greater than 0.1%, such as the case disclosed above, where calendar life data for 50% or 30% SOC is calculated given a 100% SOC. The SOC range to be calculated is any range between 1% and 100%, excluding the baseline group.

[0077] As an optional item, this embodiment proposes a calendar life test method, including the steps of:

[0078] (a) Test the room temperature capacity of the test sample battery before storage;

[0079] (b) Adjust the test sample cell to the target SOC;

[0080] (c) Adjust the incubator to the target temperature and place the battery cell in the incubator after the temperature stabilizes;

[0081] (d) Testing the remaining capacity and recovery capacity of the test sample at a frequency of 30 days or as otherwise specified;

[0082] (e) The test ends when the storage time reaches the specified time or the capacity recovery rate is ≤80%.

[0083] Further disclosed is a battery life prediction system with different SOC calendars, comprising the following structure:

[0084] A test data input unit is configured to receive calendar life data obtained by testing a reference group of battery cells at a preset temperature and a first preset time according to a calendar life test method, including calendar life and corresponding time; wherein the reference group of battery cells is a selected reference group of battery cells having a preset SOC;

[0085] a data fitting unit, configured to perform linear or polynomial fitting based on the recorded calendar life data of the reference group battery cells at the corresponding time, to derive calendar life data within a second preset time, where the second preset time is a time range after the first preset time;

[0086] The calendar life prediction unit is used to calculate the calendar life data of other SOCs different from the preset SOC using a first-order kinetic reaction formula.

[0087] Further disclosed is a battery calendar life prediction device, the device comprising: a memory and a processor;

[0088] The memory is used to store program instructions;

[0089] The processor is configured to invoke the program instructions stored in the memory to implement a method for predicting calendar life at different SOCs for a battery. The device can input test data from a reference battery pack tested according to a calendar life test method, select the SOC parameter and time to be calculated, and output calendar life data at the corresponding SOC within the required time, thereby achieving automated calculation.

[0090] In the above embodiments, the description of each embodiment has different emphases. For the parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments. The process steps discussed in the above-mentioned embodiments of this application are merely some preferred implementation methods, which are used to illustrate the feasibility of the structure described in this application and do not limit the scope of the invention. The implementation of the method of the present invention by other process methods or sequences is also within the scope of protection of the present invention. The above is only a specific implementation method of the present application, but the scope of protection of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or replacements within the technical scope disclosed in this application, which should be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A method for predicting the calendar life of batteries at different SOCs, characterized in that: The following steps are involved: Select the baseline battery pack with preset SOC; Performing calendar life testing of the reference group battery cells at a preset temperature and a first preset time according to a calendar life testing method and recording data; Fitting the recorded calendar life data of the reference group battery cells at the corresponding time to derive calendar life data within a second preset time, where the second preset time is a time range after the first preset time; Using the first-order kinetic reaction formula, calculate the calendar life data of other SOCs different from the preset SOC: The first-order kinetic reaction is: Where k is the side reaction rate that affects the calendar life, calculated using the formula SOC + (1-battery initial efficiency), t is the number of months of reaction, a is the initial SOH, for the initial new battery a = 100%, ax is the SOH after t months of reaction; The first-order kinetic reaction formula is used to calculate the side reaction rates affecting the calendar life of the preset SOC and other SOCs different from the preset SOC, and the two are compared to obtain the calendar life data of other SOCs different from the preset SOC.

2. The battery calendar life prediction method according to claim 1, characterized in that: The preset SOC of the reference group battery cells is selected from any value in the range of 1%-100%.

3. The method for predicting battery calendar life at different SOCs according to claim 1, characterized in that: The first preset time range is 1 year to 15 years.

4. The method for predicting battery calendar life at different SOCs according to claim 1, characterized in that: The preset temperature range is -30°C-60°C.

5. The method for predicting battery calendar life at different SOCs according to claim 1, characterized in that: The fitting method includes: linear fitting or polynomial fitting.

6. The method for predicting battery calendar life at different SOCs according to claim 1, characterized in that: The calculated SOC interval is greater than 0.1%.

7. A battery life prediction system with different SOC calendars, characterized in that: Includes the following structures: A test data input unit, configured to receive calendar life data obtained by testing a reference group of battery cells at a preset temperature and a first preset time according to a calendar life test method, including calendar life and corresponding time; The reference group of cells is a selected reference group of cells with a preset SOC; a data fitting unit, configured to perform linear or polynomial fitting based on the recorded calendar life data of the reference group battery cells at the corresponding time, to derive calendar life data within a second preset time, where the second preset time is a time range after the first preset time; The calendar life prediction unit is used to calculate the calendar life data of other SOCs different from the preset SOC using a first-order kinetic reaction formula, wherein the first-order kinetic reaction is: Among them, k is the side reaction rate that affects the calendar life, which is calculated using the formula SOC + (1-battery initial efficiency), t is the number of months of reaction, a is the initial SOH, for the initial new battery a = 100%, ax is the SOH after the reaction t months, The first-order kinetic reaction formula is used to calculate the side reaction rates affecting the calendar life of the preset SOC and other SOCs different from the preset SOC, and the two are compared to obtain the calendar life data of other SOCs different from the preset SOC.

8. A battery calendar life prediction device, characterized in that: The device includes: a memory and a processor; The memory is used to store program instructions; The processor is used to call the program instructions stored in the memory to implement the battery different SOC calendar life prediction method according to any one of claims 1-6.

9. A storage medium having computer program instructions stored thereon, characterized in that: When the computer program instructions are executed by a processor, the method for predicting the calendar life of a battery with different SOCs according to any one of claims 1 to 6 is implemented.

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