A method and system for rapid evaluation of residual value of lithium-ion batteries of electric vehicles

Abstract

This invention proposes a rapid method and system for assessing the residual value of lithium-ion batteries in electric vehicles. The method includes: acquiring the actual mileage and driving range of the vehicle equipped with the power battery; calculating the number of assessment cycles for the power battery based on the acquired data; finding the corresponding charge / discharge capacity decay curve of the power battery at room temperature based on the calculated number of assessment cycles; and inputting the charge / discharge capacity decay and relevant basic information of the power battery into a power battery residual value assessment model to calculate the residual value of the power battery. This method is simple and fast, requires no large-scale testing equipment or harsh testing environments, and is suitable for large-scale power battery residual value assessment scenarios.

Description

Technical Field

[0001] This invention belongs to the field of residual value assessment technology for lithium-ion batteries in electric vehicles, and particularly relates to a rapid assessment method and system for the residual value of lithium-ion batteries in electric vehicles. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Lithium-ion batteries are the primary energy storage device for electric vehicles due to their advantages such as high operating voltage, high energy density, and long cycle life. With the rapid development of electric vehicles, the installed capacity of power batteries is also increasing year by year. From a cost perspective, power batteries, as the core component of new energy vehicles, account for approximately 40% of the total vehicle cost, making them a crucial link in the entire industry chain. Power batteries are electrochemical systems that continuously degrade during their use and storage. In some cases, due to the lack of specialized charging and discharging equipment, capacity testing cannot be performed to confirm the degradation rate of the power battery. Therefore, it is necessary to create a method for rapidly assessing the residual value of power batteries based on the mileage of vehicles equipped with them and the production time of the power batteries. This method is crucial for the resale of new energy vehicles and the recycling of power batteries.

[0004] Currently, the residual value assessment method for lithium-ion power batteries involves testing with capacity and internal resistance testing equipment, followed by residual value calculation based on the test data. While this method provides accurate results, it has high requirements for testing equipment and the environment, and the assessment process is time-consuming, making it unsuitable for large-scale residual value assessments of power batteries. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, this invention provides a rapid assessment method for the residual value of lithium-ion batteries in electric vehicles. Based on data related to the vehicle's mileage and the battery's production time, the method enables a rapid assessment of the battery's residual value, resulting in a simple and quick assessment.

[0006] To achieve the above objectives, one or more embodiments of the present invention provide the following technical solutions:

[0007] Firstly, a rapid method for assessing the residual value of lithium-ion batteries for electric vehicles is disclosed, including:

[0008] Obtain the actual driving mileage and driving range of vehicles equipped with power batteries;

[0009] The evaluation cycle number of the power battery is calculated based on the data obtained above.

[0010] Based on the calculated number of power battery evaluation cycles, the normal temperature cycle test curve of the power battery is found, and the corresponding charge and discharge capacity decay is obtained.

[0011] The residual value of the power battery is calculated by inputting the charge and discharge capacity decay and related basic information of the power battery into the power battery residual value assessment model.

[0012] As a further technical solution, before obtaining the actual driving range and driving range of the vehicle equipped with the power battery, the following are also included:

[0013] The operating status information of the power battery is collected to ensure that the power battery operates within the normal range.

[0014] As a further technical solution, the operating status information of the power battery includes the static voltage difference, single cell voltage, and internal resistance of the power battery.

[0015] As a further technical solution, the vehicle's driving range needs to be calculated before calculating the evaluation cycle number of the power battery. The ratio of the actual driving range of the vehicle equipped with the power battery to the vehicle's driving range is the evaluation cycle number of the power battery.

[0016] As a further technical solution, before calculating the vehicle's driving range, it is also necessary to obtain the power battery's seasonal temperature change-based efficiency, passenger load efficiency, and final value of capacity loss. The above data are empirical values.

[0017] As a further technical solution, the formula for calculating the vehicle's driving range is:

[0018]

[0019] Where R: vehicle range; Rv: average mileage per cycle; seasonal temperature change efficiency; η2: passenger load efficiency; η3: final value of capacity loss.

[0020] As a further technical solution, the residual value assessment model for the power battery is as follows:

[0021]

[0022] Wherein, P: residual value of the power battery; S: specific value of capacity decay; Q: decay value corresponding to the number of evaluation cycles of the power battery; D1: production date of the power battery; D2: evaluation date of the power battery; α: charge and discharge decay weight; β: storage decay weight; γ: annual loss rate during storage.

[0023] Secondly, a rapid residual value assessment system for lithium-ion batteries in electric vehicles is disclosed, including:

[0024] The power battery evaluation cycle count calculation module is configured to: obtain the actual driving mileage and driving range of the vehicle equipped with the power battery; and calculate the power battery evaluation cycle count based on the obtained data.

[0025] The power battery residual value calculation module is configured to: find the power battery room temperature cycle test curve based on the calculated power battery evaluation cycle number, and obtain the corresponding charge and discharge capacity decay; input the charge and discharge capacity decay and the relevant basic information of the power battery into the power battery residual value evaluation model, and calculate the power battery residual value.

[0026] The above one or more technical solutions have the following beneficial effects:

[0027] The technical solution provided by this invention creates a model based on the vehicle mileage and production time of the power battery, thereby evaluating the residual value of the power battery. This method is simple and quick, requiring no large-scale testing equipment or harsh testing environments, and is suitable for large-scale power battery residual value evaluation scenarios.

[0028] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0029] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0030] Figure 1 This is a flowchart of a method according to an embodiment of the present invention. Detailed Implementation

[0031] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0032] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations of the present invention.

[0033] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0034] Example 1

[0035] See appendix Figure 1 As shown in the figure, this embodiment discloses a method for rapid evaluation of the residual value of lithium-ion batteries for electric vehicles, which mainly includes the following steps:

[0036] Step (1) Visual inspection:

[0037] The appearance of the power battery is inspected to confirm whether there are any problems such as casing deformation, cracking, water immersion, or missing parts. If the power battery does not have any of the above appearance problems, proceed to the next step;

[0038] Step (2) Information Collection:

[0039] Information about the power battery was collected via a host computer. It was confirmed that sensors for voltage and temperature were functioning normally, and that parameters such as static differential pressure, individual cell voltage, and internal resistance within the power battery met requirements. It should be noted that different battery packs have different requirements. The next step will then proceed. The collected power battery information mainly includes battery parameters such as temperature, temperature difference, static differential pressure, and individual cell voltage.

[0040] Step (3) Processing mileage data:

[0041] The driving range data (L) can be converted into the battery evaluation cycle number (Cycle) using formulas 1 and 2:

[0042] Formula 1:

[0043] Formula 2:

[0044] L: Actual driving range of the vehicle equipped with this power battery;

[0045] Cycle: The number of battery cycles used for power battery evaluation;

[0046] R: The vehicle's driving range;

[0047] Rv: Average distance traveled per cycle;

[0048] η1: Efficiency of seasonal temperature change conversion, as different ambient temperatures result in different vehicle mileages;

[0049] η2: Passenger load efficiency, the change in vehicle range due to passenger weight;

[0050] η3: Final value of capacity loss. When the capacity of the power battery drops to this value, the power battery must be scrapped.

[0051] η1, η2, and η3 are all empirical coefficients, with η1 ranging from 0.7 to 0.95, η2 ranging from 0.6 to 1, and η3 ranging from 0.6 to 0.85.

[0052] For example, if a vehicle equipped with a power battery has a driving range of 40,171 kilometers, then by applying formulas 1 and 2, the estimated cycle number of the power battery can be calculated as follows:

[0053] Formula 1:

[0054] Formula 2:

[0055] It should be noted that current assessments require specialized charging and discharging equipment to perform capacity testing and confirm the battery degradation rate. The technical solution of this invention does not require capacity and internal resistance testing equipment for residual value evaluation; it only requires substituting data such as vehicle mileage into the formula to obtain the battery residual value.

[0056] Step (4) Residual Value Assessment of Power Battery

[0057] Battery capacity degradation leads to a decrease in vehicle range, thus reducing the battery's value. Irreversible battery degradation is typically categorized into two types: charge / discharge degradation and storage degradation. Both types result in capacity loss, and both degradation models must be considered in battery residual value assessment. However, when a battery's capacity loss reaches a certain value, it can be assumed that the battery has no residual value and must be scrapped. The battery residual value assessment model is as follows:

[0058]

[0059] P: Residual value of the power battery;

[0060] S: Specific capacity decay value; This parameter is specified by the battery manufacturer or the car manufacturer, and different car manufacturers have different specific capacity decay values.

[0061] Q: The degradation value corresponding to the number of evaluation cycles of a power battery;

[0062] D1: Production date of the power battery;

[0063] D2: Power battery evaluation date;

[0064] α: Charge / discharge attenuation weight;

[0065] β: Shelving decay weight;

[0066] γ: Annual loss rate during storage; α, β and γ are empirical parameters, and battery manufacturers or car companies have different parameters depending on the performance of different batteries.

[0067] The above P value is the residual value of the power battery.

[0068] The above model is simple and quick to use, without the need for instrument testing or computer simulation.

[0069] Based on the power battery evaluation cycle count of 201 calculated in step (3), and by looking up the power battery room temperature cycle test curve, the corresponding charge and discharge capacity decay (Q) is 5.4%.

[0070] By checking the traceability code recorded on the power battery, its production date (D1) is September 10, 2020, and the current assessment date (D2) is September 10, 2022. Based on experience, the annual loss parameter for this model of battery pack under normal temperature storage is 2.8%.

[0071] If the capacity loss of a power battery reaches 25%, it can be considered that the battery's usability is 0%. Based on the above power battery residual value assessment model, the residual value of the power battery can be calculated as follows:

[0072]

[0073] The technical solution of this invention eliminates the need for residual value evaluation after testing with capacity and internal resistance testing equipment. It only requires substituting data such as vehicle mileage into a formula to obtain the battery residual value. This allows for rapid evaluation of a single battery, making it suitable for large-scale battery testing scenarios.

[0074] Example 2

[0075] The purpose of this embodiment is to provide a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps of the above-described method.

[0076] Example 3

[0077] The purpose of this embodiment is to provide a computer-readable storage medium.

[0078] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, performs the steps of the above method.

[0079] Example 4

[0080] The purpose of this embodiment is to provide a rapid residual value assessment system for lithium-ion batteries in electric vehicles, including:

[0081] The power battery evaluation cycle count calculation module is configured to: obtain the actual driving mileage and driving range of the vehicle equipped with the power battery; and calculate the power battery evaluation cycle count based on the obtained data.

[0082] The power battery residual value calculation module is configured to: find the power battery room temperature cycle test curve based on the calculated power battery evaluation cycle number, and obtain the corresponding charge and discharge capacity decay; input the charge and discharge capacity decay and the relevant basic information of the power battery into the power battery residual value evaluation model, and calculate the power battery residual value.

[0083] The steps and methods involved in the apparatuses of Embodiments 2, 3, and 4 above correspond to those in Embodiment 1. For specific implementation details, please refer to the relevant description section of Embodiment 1. The term "computer-readable storage medium" should be understood as a single medium or multiple media including one or more instruction sets; it should also be understood as including any medium capable of storing, encoding, or carrying an instruction set for execution by a processor and enabling the processor to perform any of the methods in this invention.

[0084] Those skilled in the art will understand that the modules or steps of the present invention described above can be implemented using general-purpose computer devices. Optionally, they can be implemented using computer-executable program code, thereby allowing them to be stored in a storage device for execution by a computer device, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. The present invention is not limited to any particular combination of hardware and software.

[0085] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A rapid method for assessing the residual value of lithium-ion batteries for electric vehicles, characterized in that, include: Obtain the actual driving mileage and driving range of vehicles equipped with power batteries; The evaluation cycle number of the power battery is calculated based on the data obtained above. Before calculating the evaluation cycle number of the power battery, the vehicle's driving range needs to be calculated first. The ratio of the actual driving range of a vehicle equipped with a power battery to the vehicle's driving range is the evaluation cycle number of the power battery. Before calculating the vehicle's driving range, it is also necessary to obtain the seasonal temperature change-based efficiency, passenger load efficiency, and final value of capacity loss of the power battery. The above data are empirical values. The formula for calculating a vehicle's driving range is: Where R: vehicle range; Rv: average mileage per cycle; seasonal temperature variation efficiency; η2: passenger load efficiency; η3: final value of capacity loss; Based on the calculated number of power battery evaluation cycles, the normal temperature cycle test curve of the power battery is found, and the corresponding charge and discharge capacity decay is obtained. Where Cycle is the number of evaluation cycles of the power battery; L is the actual driving mileage of the vehicle equipped with the power battery; and Rv is the average mileage per cycle. Input the charge and discharge capacity decay and relevant basic information of the power battery into the power battery residual value assessment model to calculate the residual value of the power battery. The residual value assessment model for the power battery is as follows: Wherein, P: residual value of the power battery; S: specific value of capacity decay; Q: decay value corresponding to the number of evaluation cycles of the power battery; D1: production date of the power battery; D2: evaluation date of the power battery; α: charge and discharge decay weight; β: storage decay weight; γ: annual loss rate during storage.

2. The method for rapid residual value assessment of lithium-ion batteries for electric vehicles as described in claim 1, characterized in that, Before obtaining the actual driving range and driving range of vehicles equipped with power batteries, the following is also included: The operating status information of the power battery is collected to ensure that the power battery operates within the normal range.

3. The method for rapid residual value assessment of lithium-ion batteries for electric vehicles as described in claim 2, characterized in that, The operating status information of the power battery includes the static voltage difference, single cell voltage, and internal resistance of the power battery.

4. A rapid residual value assessment system for lithium-ion batteries in electric vehicles, characterized in that, include: The power battery evaluation cycle count calculation module is configured to: obtain the actual driving mileage and driving range of the vehicle equipped with the power battery; and calculate the power battery evaluation cycle count based on the obtained data. Before calculating the evaluation cycle number of the power battery, the vehicle's driving range needs to be calculated first. The ratio of the actual driving range of a vehicle equipped with a power battery to the vehicle's driving range is the evaluation cycle number of the power battery. Before calculating the vehicle's driving range, it is also necessary to obtain the seasonal temperature change-based efficiency, passenger load efficiency, and final value of capacity loss of the power battery. The above data are empirical values. The formula for calculating a vehicle's driving range is: Where R: vehicle range; Rv: average mileage per cycle; seasonal temperature variation efficiency; η2: passenger load efficiency; η3: final value of capacity loss; Where Cycle is the number of evaluation cycles of the power battery; L is the actual driving mileage of the vehicle equipped with the power battery; and Rv is the average mileage per cycle. The power battery residual value calculation module is configured to: find the power battery room temperature cycle test curve based on the calculated power battery evaluation cycle number, and obtain the corresponding charge and discharge capacity decay; input the charge and discharge capacity decay and the relevant basic information of the power battery into the power battery residual value evaluation model, and calculate the power battery residual value. The residual value assessment model for the power battery is as follows: Wherein, P: residual value of the power battery; S: specific value of capacity decay; Q: decay value corresponding to the number of evaluation cycles of the power battery; D1: production date of the power battery; D2: evaluation date of the power battery; α: charge and discharge decay weight; β: storage decay weight; γ: annual loss rate during storage.

5. The rapid residual value assessment system for lithium-ion batteries in electric vehicles as described in claim 4, characterized in that, Before obtaining the actual driving range and driving range of a vehicle equipped with a power battery, the following steps are also required: The operating status information of the power battery is collected to ensure that the power battery operates within the normal range.

6. The rapid residual value assessment system for lithium-ion batteries in electric vehicles as described in claim 5, characterized in that, The operating status information of the power battery includes the static voltage difference, single cell voltage, and internal resistance of the power battery.

7. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps of the method described in any one of claims 1-3.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it performs the steps of the method described in any of claims 1-3 above.

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