JP3239547U - Lithium-ion battery soundness and remaining useful life measurement system - Google Patents

Abstract

A measurement system capable of accurately and quickly predicting the state of health and remaining useful life of a lithium-ion battery applied under various operating conditions such as different environmental temperatures and different discharge rates is provided. A recording unit (101, 102) for recording the charging current and discharging current of a lithium ion battery, recording the discharging temperature and the corresponding discharging current of each discharging cycle, and recording the number of charging/discharging cycles; After selecting said charge/discharge cycle of said verified lithium ion battery, computing an electrochemical electrical model for said health value of said lithium ion battery, and electrochemical electrical model for said obtained health value. is used to connect the calculation units 103 and 104 that calculate the parameters of the semi-empirical capacity fading model, and the lithium ion battery is connected to the cloud, and after confirming the numerical value obtained by the calculation, it is transmitted to the application, and the result and a display unit 105 for displaying on the screen. [Selection drawing] Fig. 1

Description

The present invention relates to a method for measuring the health level and remaining useful life of a lithium ion battery, and more particularly to a method for accurately and immediately predicting the health level and remaining useful life of a lithium ion battery.

Electric vehicles (EV) have received the most attention in the development of the modern automobile industry, especially for electric vehicles powered by rechargeable lithium-ion batteries (LiB). Expectations have always been high for the high efficiency and long service life of rechargeable lithium-ion batteries. However, it is extremely difficult to ascertain the state-of-health (SoH) of lithium-ion batteries and predict their remaining useful life (RUL) in related fields. This is the current situation. In fact, it is still an insurmountable problem in related industries to accurately and quickly measure the health of the lithium ion battery.

In addition, the state-of-health (SoH), state-of-charge (SoC), state-of-energy (SoE), and state-of-safety (SoS) of lithium-ion batteries An important health index for lithium-ion batteries has been widely discussed. The reason for this is that if the state of health of the lithium-ion battery cannot be measured accurately, the actual residual charge of the lithium-ion battery, that is, the amount of charge in general, will be much lower than expected, which can lead to unexpected over-discharge (over discharge). This is because there is a risk of causing a discharge).

In addition, if the remaining service life of the lithium ion battery is unknown, the user may replace the lithium ion battery without waiting for the scheduled replacement time, resulting in an increase in the usage cost of the lithium ion battery. On the other hand, trying to extend the service life of lithium-ion batteries, which are actually less than 80% healthy, may lead to more serious problems.

Accurately evaluating the health of lithium-ion batteries and predicting their remaining service life are therefore of the utmost importance when using lithium-ion batteries, especially in the field of electric vehicles. Currently, there are many soundness evaluation methods, and some evaluation methods can be said to be highly accurate. And from a practical point of view, the lack of speed and accuracy is highly questionable.

In response to this, the related fields of the electric vehicle industry are now able to effectively evaluate the health of lithium-ion batteries, and formulate optimal plans that can clearly grasp and predict the remaining service life of lithium-ion batteries. is urgent. Therefore, if we can provide a method that can accurately and quickly predict the state of health and remaining useful life of lithium-ion batteries, it will be an epoch-making achievement that has been expected and attracting attention in the electric vehicle-related industry.

The lithium-ion battery health and remaining service life prediction method disclosed in the present invention can be applied to lithium-ion batteries under various operating conditions, such as different environmental temperatures and different discharge rates, to accurately and immediately It is a method that can predict the state of health and the remaining service life of the battery.

The method for measuring the health degree and remaining service life of the lithium ion battery disclosed in the present invention is to first record the charge current and discharge current of the lithium ion battery, then the discharge temperature and discharge current of each discharge cycle, and then charge/discharge. Record the number of cycles. Subsequently, at least three determined lithium-ion battery charge/discharge cycles are selected in advance, and the numerical value of the health of the lithium-ion battery is calculated. Then, the "parameter values of the semi-empirical capacity fading model" are calculated using the acquired soundness values. Finally, after connecting the lithium-ion battery to the cloud and confirming the numerical values obtained by calculation, the data is sent to the application and the results are displayed on the screen.

The lithium-ion battery health and remaining service life measurement method disclosed in the present invention combines the "electrochemical electrical model" and the "semi-empirical capacity fading model" with each other, and applies them to the discharge curve of the lithium-ion battery. The aim is to achieve an estimation accuracy of 99% or higher by evaluating the maximum charge capacity, soundness and service life of lithium-ion batteries under all operating conditions.

The method for measuring the soundness and remaining service life of lithium-ion batteries disclosed in the present invention can be used as an accelerated life measurement method for lithium-ion batteries, and can be used to measure the service life of lithium-ion batteries manufactured in the same lot at the factory. The purpose is to be able to predict the quality and reliability of lithium-ion batteries manufactured from the relevant lot. Furthermore, the present invention is a closed model and the "estimated time" to use is less than 5 seconds, so it applies to the field of instant online connection.

The method for measuring the state of health and the remaining service life of the lithium-ion battery disclosed in the present invention is very important in the requirement of accurately connecting to the online and predicting the battery capacity and the remaining service life of the lithium-ion battery. , the present invention has the advantage of using a semi-empirical capacity fading model to assess the health and predict the remaining useful life after different discharge cycles when the lithium-ion battery is in operation.

The method disclosed in the present invention for measuring the state of health and the remaining service life of the lithium ion battery has the advantage that the accuracy of the present invention is more than 99% regardless of the discharge current and the ambient temperature.

The method of measuring the soundness and remaining useful life of the lithium-ion battery disclosed in the present invention is a tight closed form, and can be used to estimate the life cycle of the lithium-ion battery. It has the advantage that it can be applied to immediately evaluate the health of a lithium-ion battery.

The method for measuring the health and remaining service life of lithium-ion batteries disclosed in the present invention is to measure the maximum residual storage capacity of lithium-ion batteries after multiple charge/discharge cycles for the health of lithium-ion batteries. Based on the degree of decrease in the maximum storage capacity of the lithium-ion battery, the state of health of the lithium-ion battery can reasonably be assumed to be related to the number of discharge cycles, the number of discharge currents, and the temperature.

The method for measuring the health and remaining useful life of lithium-ion batteries disclosed in this invention can be predicted by evaluating the health of lithium-ion batteries at different temperatures and discharge rates, and can be easily and quickly realized. When determining battery health, there is an advantage in being able to predict the service life of lithium-ion batteries down to 80% charge/discharge cycles.

The foregoing and many other advantages disclosed by the present invention are described in detail with reference to the following drawings, in which: FIG.

1 is a flowchart of a method for measuring health and remaining service life of a lithium ion battery disclosed in the present invention; FIG.

Embodiments disclosed in the present invention will be described below with reference to the accompanying drawings. In the drawings, like reference numerals refer to like parts, and the size or thickness of the parts may be exaggerated for clarity of explanation.

The method of measuring the soundness and remaining useful life of the lithium-ion battery disclosed in the present invention is based on the lithium-ion battery of catalog number SANYO UR18650E from Panasonic and the multi-channel output charge/discharge measurement system from Bio-Logic (product No. BCS-815) was used for measurements. The multi-channel output charging/discharging measurement system can be used with 8 channels, each channel supports 15 amperes (A), and the multi-room temperature (about 25 ^o C), collects the measurement data generated through the lithium ion battery, and The sample frequency of acquisition is 1 Hz.

FIG. 1 is a flow chart of the method for measuring the state of health and the remaining useful life of a lithium ion battery disclosed in the present invention. Step 101 shown in FIG. 1 records the charging and discharging currents of a lithium-ion battery. Normally, the charging current and discharging current of the battery immediately after shipment are recorded, but since the battery is measured under different measurement conditions, in this case, the charging current and discharging current of the battery are recorded one or more times. In addition, in the present invention, the battery is charged before use, and after the battery is charged to the final discharge voltage with a constant current, the battery is charged with a constant voltage until the current drops to 100mA.

Step 102 shown in FIG. 1 records the discharge temperature and discharge current for each discharge cycle, as well as the number of charge/discharge cycles. A charge/discharge cycle as used herein refers to each cycle including a charge process and a discharge process.

In step 103 shown in FIG. 1, after selecting at least two pre-confirmed charge/discharge cycles of the lithium-ion battery, a numerical value of the state of health of the lithium-ion battery, the "electrical model of electrochemistry (SoH)" is calculated. In other words, the numerical value of the degree of health is obtained after measuring the lithium-ion battery of the first cycle (Qmax (fresh) parameter and after the process of the aging deterioration (Qmax (aged) parameter of the lithium-ion battery), the first cycle (Qmax (fresh ) parameter divided by the (Qmax(aged) parameter, the value of the soundness obtained is the maximum battery capacity value of the next lithium-ion battery.

Equation 1 below is the equation of the "Electrical Model of Electrochemistry" mentioned above.

Further, step 104 shown in FIG. 1 uses the acquired health degree values, the "electrochemical electrical model," to determine the values of the following "semi-empirical capacitive fading model (SECF)": of the parameters) were calculated.

Equation 2 below is the formula for the "semi-empirical capacity fading model" mentioned above.

At step 104 shown in FIG. 1, each parameter of the following "semi-empirical capacity fading model" is displayed.

In step 104 shown in FIG. ₁ , parameter k1 represents the rapidly increasing capacity loss of the lithium-ion battery under conditions of high temperature cycling.

Also shown in FIG. 1, at step 104, parameter k2 indicates a possible contributor to the capacity loss of a lithium _- ion battery under normal cycling conditions.

Further, in step 104 shown in FIG. 1, the capacity loss caused by the usage rate of the lithium _- ion battery is indicated at parameter k3.

Subsequently, in step 104 shown in FIG. 1, parameter N indicates the number of charge/discharge cycles over time when the lithium-ion battery is in a healthy stage, and parameter i indicates the current during discharge.

In step 104 shown in FIG. 1, said parameters, including parameter k ₁ , parameter k ₂ and parameter k ₃ , are obtained through three different charge/discharge cycles to obtain lithium by the maximum cycle selected from the three cycles. Ensure that the ion battery health is half of the cycle at about 80%.

Finally, in step 105 shown in FIG. 1, after connecting the lithium ion battery to the cloud and confirming that the numerical value obtained in the above calculation is correct, the finally calculated numerical value obtained is Send to the application (App) and display the result on the screen (screen display).

In addition, using step 104 "Semi-empirical capacity fading model" shown in FIG.

The number 80 above indicates the remaining useful life. In other words, the usable total storage capacity (Q _m ) of the lithium ion battery must be 80% or more, which can be obtained by calculation.

The method for measuring the state of health and the remaining useful life of the lithium ion battery disclosed in the present invention is the "electrochemical electrical model" in step 103 shown in FIG. 1 and the "semi-empirical capacity fading model" in step 104 shown in FIG. By using these for the discharge curve of the lithium-ion battery, we can evaluate the maximum charge capacity, soundness and service life of the lithium-ion battery under all operating conditions, with an accuracy of 99% or more. We estimate that In addition, the present invention can be used as a method for measuring the accelerated deterioration of lithium-ion batteries, and in addition to measuring the service life of the same lot of lithium-ion batteries produced in the factory, it can also be used to measure the quality and reliability of the same lot of lithium-ion batteries. It can also be applied to sex testing. Furthermore, the present invention applies to instant connection applications, as it is a closed model and uses an "estimated time" of 5 seconds or less.

The present invention is based on the fact that it is very important to have an accurate online prediction for the battery capacity and its remaining service life of the lithium-ion battery, and the semi-empirical capacity fading (SECF) is used in the present invention. A model is used to estimate the health and it's remaining useful life after different discharge cycles while the lithium-ion battery is in operation. In addition, regardless of the discharge current and ambient temperature, the accuracy of the present invention can be ensured above 99%. The present invention is a tight closed form and can be used for life cycle prediction of lithium-ion batteries. Therefore, the present invention can also be applied to connecting a lithium ion battery online and estimating the state of health immediately.

Although specific examples of the present invention have been described in detail above, these are merely examples, and do not limit the scope of claims for utility model registration. Also, various changes or modifications may be made without departing from the scope and spirit of the invention.

101 Record the charge and discharge currents of the lithium-ion battery 102 Record the discharge temperature and discharge current for the discharge cycle 103 Calculate the “Electrical Model of Electrochemistry” 104 Calculate the “Semi-Empirical Capacitance Fading Model” 105 Check the numbers then send it to the application and display it on the screen

Claims (4)

a recording unit for recording the charging current and discharging current of the lithium ion battery, recording the discharging temperature and the discharging current of each discharging cycle, and recording the number of charging/discharging cycles;
After selecting said charge/discharge cycles for said at least two verified said lithium ion batteries, calculating an electrochemical electrical model for said health values of said lithium ion batteries, and electrochemistry for said obtained health values. a calculator that calculates the parameters of the semi-empirical capacitive fading model using the electrical model of
a display unit that connects the lithium ion battery to the cloud, checks the numerical value obtained by calculation, transmits the result to the application, and displays the result on the screen;
A system for measuring the soundness and remaining service life of a lithium-ion battery, comprising: Including the numerical value of the soundness obtained by the following formula 1,

2. The system of claim 1, wherein Qmax(fresh) is the first cycle parameter and Qmax(aged) is the aging parameter. including the semi-empirical capacity fading model obtained by Equation 2 below,

Among them, the parameter k1 indicates the rapidly increasing capacity loss under the condition of high _- temperature cycling of lithium-ion batteries,
The parameter k2 represents one factor of possible capacity loss under conditions of normal cycling of lithium _- ion batteries,
The parameter _k3 indicates the capacity loss due to the usage rate of the lithium-ion battery,
the parameter N indicates the number of charge/discharge cycles over time when the lithium ion battery is in good condition;
2. The system of claim 1, wherein the parameter i is the current during discharge. 4. The system of claim 3, wherein said semi-empirical capacity fading model includes a remaining useful life of 80%.

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