CN116068316B - Application of chromatic aberration technology in detecting state of energy storage device - Google Patents

Abstract

The invention belongs to the technical field of detection of states of energy storage devices, and particularly relates to application of a chromatic aberration technology in detection of states of different parts of an energy storage device. The color difference technology is applied to detecting the state of the energy storage device, and an in-situ color test is carried out on any area of the energy storage device along with charge and discharge, a current collector and temperature change by using a color meter to obtain the color data change of the tested area of the energy storage device, so that the state change of any area of the energy storage device is evaluated by using the color difference technology. The detection method based on the color difference technology can intuitively and accurately verify the state change of the energy storage electrode material in the energy storage device in real time in the charge-discharge process, namely the provided color signal and the color difference change can accurately, quickly and in-situ reflect the charge-discharge state change of the energy storage electrode material, so that a new path is provided for the performance supervision and evaluation of the energy storage material in the energy storage device, and the detection method is a detection method with a very good application prospect.

Description

Application of a color difference technology in detecting the state of energy storage devices

Technical Field

The present invention belongs to the technical field of detecting the state of an energy storage device, and specifically relates to an application of a color difference technology in detecting the states of different components of an energy storage device.

Background Art

The development of social economy and science and technology has put forward higher requirements for energy storage systems. How to achieve efficient and low-cost storage and conversion of energy has become a strategic support for promoting the transformation of energy structure and optimizing the transformation of electricity production and consumption. It is also one of the research hotspots in the field of energy storage. Common and widely studied energy storage systems include lithium-ion batteries, sodium-ion batteries, nickel-cadmium batteries and supercapacitors. Among them, energy storage electrode materials have attracted widespread attention as the key to the use and development of energy storage systems. At present, in addition to the need to further explore new high-performance energy storage devices, the supervision, detection, evaluation and analysis of the operation of energy storage devices are also the key to achieving their efficient, rapid and stable development. There are still many issues worth further exploration. On the one hand, it is difficult for these energy storage devices to maintain perfect electrical properties all the time. After use, they often experience degradation and failure of components such as electrolytes and electrodes, which means that their energy storage capacity is reduced. If the failed part of each component is located in time and the cause of the failure is eliminated, the energy storage element with degraded performance can be avoided or repaired in a timely and targeted manner; on the other hand, in the face of the problem that energy storage devices such as lithium-ion battery packs are prone to fire or explosion due to overcharging, short circuit, thermal runaway, etc., it is very necessary to develop thermal management test technology and analysis models to study and monitor the thermal behavior of lithium-ion battery packs, etc.

In the past few decades, many methods have been developed to explore the electrical properties, failure mechanisms and safety issues of energy storage devices. Among them, electrical signal characterization is the most basic detection method and has been widely used to characterize its current, voltage, power, capacity and stability. In addition, X-ray tomography and neutron scattering methods are used to characterize the internal structure of encapsulated commercial lithium battery packs, and ultrasonic imaging technology is developed to study the wetting process and interface stability of soft-pack batteries. However, considering the current large-scale application trend of batteries and supercapacitors and people's increasing attention to safety issues, the above detection technologies cannot simultaneously and efficiently meet the performance evaluation and thermal supervision of energy storage devices. Therefore, in response to the needs of more accurate and safer energy storage devices, it is very necessary to explore a new type of fast, sensitive, economical, in-situ, non-destructive testing advanced technology.

Summary of the invention

In view of the above problems existing in the prior art, the purpose of the present invention is to provide an application of color difference technology in detecting the state of energy storage devices. This application can solve the shortcomings of the existing testing methods that cannot test multiple states and performances of energy storage devices in real time and simultaneously.

To achieve the above object, the present invention discloses the following technical solutions:

An application of color difference technology in detecting the state of energy storage devices, using a colorimeter to perform in-situ color testing on any area of the energy storage device as the charge and discharge, current collector and temperature change, obtain the color data change of the tested area of the energy storage device, and thus realize the independent evaluation of the state change of any area of the energy storage device by color difference technology. The specific method used is:

(1) Using a colorimeter to test any part of the energy storage device of the energy storage device;

(2) The obtained color data is recorded, and the status of different components of the energy storage device is characterized in real time and losslessly by analyzing the degree of change of the color data.

Furthermore, the colorimeter can be a desktop spectrophotometer, a handheld spectrophotometer, an online spectrophotometer, a spectrophotometer (for example, a spectrophotometer using a 0°/45° measurement structure or a d/8 integrating sphere measurement structure, etc.), a photoelectric integrating colorimeter, a spectral scanning colorimeter, a digital camera, a spectral imaging technology, and a series of other instruments and technologies that all use the same, similar or different principles to obtain color data sets.

Further, the energy storage device is an energy storage system with ion transfer or valence state transition. More preferably, the energy storage device with ion transfer or valence state transition is a metal ion battery system, a negative ion battery system, an aqueous and organic supercapacitor, a nickel-cadmium battery, a metal/sulfur battery or a flexible polymer energy storage device.

Furthermore, the method of obtaining the color data change of the tested area of the energy storage device is to express and record the color changes of different components of the tested energy storage device in the form of numbers using a color standard; wherein the color standard is one or more color models such as CIEXYZ, CIELAB, CIELUV, CIEUVW, YUV, HSL/HSV, RGB and CMYK.

The color difference data is used to quantify the degree of color change in a certain direction. The color difference data can be in the form of data obtained by any processing and calculation method based on any color model, and is not limited to a certain color difference formula. The formula for calculating color difference can be the color difference formula specified by the CIE organization, or it can be a color difference formula specially specified by humans based on usage needs.

The present invention detects the electrical performance operating state of the energy storage device through color signals and color difference changes, and simultaneously monitors its temperature, which is of great significance for achieving efficient operation of the energy storage and conversion process of the energy storage device.

The states of the energy storage device include operation/non-operation state, voltage change, capacity change (one or more of stability, increase, decrease and failure), selection of different current collectors, component temperature change and other related state changes.

The present invention can realize the detection of energy storage devices through the above application, including:

(1) Realize real-time detection of the overall working and operating status of each component of the energy storage device, such as: determination of operating/non-operating status, voltage change, capacity change (stable, boost, and attenuation);

(2) Independently evaluate any location of the energy storage device, for example, it can distinguish between normal areas, performance degradation areas, and completely damaged areas on the energy storage material;

(3) The color changes of the electrode materials caused by using different materials as current collectors in energy storage devices are distinguished, and the influence of the current collector itself on the electrical properties of the energy storage material is independently evaluated by the color difference value.

(4) Monitor the temperature changes of energy storage device components such as energy storage materials, shells and diaphragms in non-operating and operating states to monitor the thermal-related performance of energy storage devices.

The basic principle of the present invention is:

During the operation of the energy storage device, that is, during its charging and discharging process, the material and its environment will undergo continuous dynamic changes. For any electrode material and its environment, one or more of the following changes will inevitably occur during the operation process, including but not limited to: ① carrier embedding and extraction; ② carrier adsorption and desorption; ③ valence state change of electrode material; ④ structural change of electrode material (such as crystal structure change, crystal form transformation, crystal structure collapse, etc.); ⑤ generation of by-products; ⑥ electrode material failure (electrode material breakage or detachment, electrode material denaturation, etc.). For all components of the energy storage device that experience temperature changes, any one or more of these changes will cause the color of the electrode or other components to change.

By using a colorimeter, these colors and the degree of color change can be accurately measured and calculated. Specifically, the colorimeter measures the light source data of the sample at each wavelength, that is, the reflectance spectrum, and then converts it into color data based on the color model. Commonly used color models include CIEXYZ, CIELAB, CIELUV, CIEUVW, YUV, HSL/HSV, RGB and CMYK. Furthermore, data can be compared and calculated in different color spaces. In theory, all color spaces and calculations for measuring the degree of color change are applicable to the present invention.

Compared with the prior art, the advantages of the present invention are:

(1) The color difference technology detection method provided by the present invention can verify the state change of the energy storage electrode material in the energy storage device during the charge and discharge process in real time, intuitively and accurately, that is, the color signal and color difference change provided by the present invention can accurately, quickly and in situ reflect the change of its charge and discharge state, thereby providing a new path for the performance supervision and evaluation of the energy storage material in the energy storage device, and is a detection method with great application prospects;

(2) The color difference technology-based detection method provided by the present invention is applicable to a variety of test situations, and can realize the detection of overall state changes of various components of the energy storage device, and can also realize independent detection of state changes of any area of each component.

(3) The color difference detection method provided by the present invention can distinguish the color changes of current collectors of different materials selected for energy storage devices, and independently evaluate the influence of the current collector itself on the electrical properties of the energy storage material by the color difference value.

(4) The color difference detection method provided by the present invention can directly characterize the temperature change of the energy storage material under the working/non-working state, thereby realizing the monitoring of the temperature change of the electrode material;

(5) The present invention provides an in-situ color difference testing technology that is adaptable to a variety of complex situations. The detection method can simultaneously realize the detection of the charging and discharging state of the energy storage device, the detection of performance degradation/failure in any area of the electrode, the detection of the influence of different current collectors on the electrode performance, and the detection of temperature changes of different components;

(6) This detection method has a wide range of applications and can be applied to metal (lithium, sodium, magnesium, aluminum, etc.) ion battery systems, negative ion battery systems, aqueous and organic supercapacitors, nickel-cadmium batteries, metal (lithium, sodium, magnesium, aluminum, etc.)/sulfur batteries, flexible polymer energy storage devices, and other energy storage devices with ion transfer or valence state transition;

(7) This detection method is applicable to a variety of energy storage device structures such as button batteries and soft-pack batteries, and has broad practical application prospects.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings constituting a part of the specification of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their description are used to explain the present invention and do not constitute an improper limitation of the present invention. The embodiments of the present invention are described in detail below in conjunction with the drawings, wherein:

FIG1 is a charge and discharge curve of the Ni(OH) ₂ electrode obtained in Example 1 in the voltage range of 0-0.5V;

FIG2 is a series of reflection spectra of the Ni(OH) ₂ electrode obtained in Example 1 during the charge and discharge process;

FIG3 is a curve showing the change of X, Y, and Z values of the Ni(OH) ₂ electrode obtained in Example 1 during the charge and discharge process as a function of the charge and discharge time;

FIG4 is a curve showing the change of L ^* , a ^* , and b ^* values of the Ni(OH) ₂ electrode obtained in Example 1 during the charge and discharge process as a function of the charge and discharge time;

FIG5 is a curve showing the change of L ^* , u ^* , and v ^* values of the Ni(OH) ₂ electrode obtained in Example 1 during the charge and discharge process as a function of the charge and discharge time;

FIG6 is a curve showing the variation of ΔL ^* , Δa ^* , and Δb ^* values of the Ni(OH) ₂ electrode obtained in Example 1 during the charge and discharge process as a function of the charge and discharge time;

FIG. 7 is a curve showing the variation of ΔL ^* , Δu ^* , and Δv ^* values of the Ni(OH) ₂ electrode obtained in Example 1 during the charge and discharge process as a function of the charge and discharge time;

FIG8 is a graph showing the ΔE ^* _ab -time variation curve and ΔE ^* _uv -time variation curve of the Ni(OH) ₂ electrode obtained in Example 1;

FIG9 is a graph showing the change in specific capacity-MAX (ΔE ^* _ab ) of the Ni(OH) ₂ electrode obtained in Example 1;

FIG10 is a charge and discharge curve of the graphite button battery obtained in Example 2 within a voltage range of 0-2V;

FIG11 is a series of reflection spectra of the graphite electrode of the graphite button cell obtained in Example 2 during the charge and discharge process;

12 is a graph showing the change of X, Y, and Z values of the graphite electrode of the graphite button battery obtained in Example 2 during the charge and discharge process as a function of the charge and discharge time;

13 is a curve showing the change of L ^* , a ^* , and b ^* values of the graphite electrode of the graphite button battery obtained in Example 2 during the charge and discharge process as a function of the charge and discharge time;

14 is a curve showing the change of L ^* , u ^* , and v ^* values of the graphite electrode of the graphite button battery obtained in Example 2 during the charge and discharge process as a function of the charge and discharge time;

15 is a curve showing the variation of ΔL ^* , Δa ^* , and Δb ^* values of the graphite electrode of the graphite button battery obtained in Example 2 during the charge and discharge process as a function of the charge and discharge time;

16 is a curve showing the variation of ΔL ^* , Δu ^* , and Δv ^* values of the graphite electrode of the graphite button battery obtained in Example 2 during the charge and discharge process as a function of the charge and discharge time;

17 is a graph showing a ΔE ^* _ab -time variation curve and a ΔE ^* _uv -time variation curve of the graphite electrode of the graphite button battery obtained in Example 2;

18 is a graph showing the change in specific capacity-MAX (ΔE ^* _ab ) of the graphite electrode of the graphite button cell obtained in Example 2;

FIG19 is a charge and discharge curve of the lithium manganate button battery obtained in Example 3 within a voltage range of 3-4.3V;

FIG20 is a series of reflection spectra of the lithium manganese oxide electrode of the lithium manganese oxide button cell obtained in Example 3 during the charge and discharge process;

21 is a curve showing the change of X, Y, and Z values of the lithium manganese oxide electrode of the lithium manganese oxide button cell obtained in Example 3 during the charge and discharge process as a function of the charge and discharge time;

22 is a curve showing the change of L ^* , a ^* , and b ^* values of the lithium manganate electrode of the lithium manganate button cell obtained in Example 3 during the charge and discharge process as a function of the charge and discharge time;

23 is a curve showing the change of ΔL ^* , Δa ^* , and Δb ^* values of the lithium manganese oxide electrode of the lithium manganese oxide button cell obtained in Example 3 during the charge and discharge process as a function of the charge and discharge time;

FIG24 is a line graph of the ΔE ^* _ab -time variation curve of the lithium manganese oxide electrode of the lithium manganese oxide button cell obtained in Example 3;

FIG25 is a charge and discharge curve of the lithium cobalt oxide button battery obtained in Example 4 within a voltage range of 2.6-4.3 V;

FIG26 is a line graph of the ΔE ^* _ab -time variation curve of the lithium cobalt oxide electrode of the lithium cobalt oxide button cell obtained in Example 4;

FIG27 is a charge and discharge curve of the lithium iron phosphate button battery obtained in Example 5 within a voltage range of 2.6-3.6V;

FIG28 is a graph showing the ΔE ^* _ab -time variation of the lithium iron phosphate electrode of the lithium iron phosphate button cell obtained in Example 5;

29 is a line graph showing the voltage change of the Ni(OH) ₂ electrode obtained in Example 6 during the 0-0.4V charge and discharge process and the ΔE ^* _ab -time change curves of the normal discharge, partial failure and complete failure parts;

FIG30 is a ΔE ^* _ab -temperature variation curve of different parts of the non-operating supercapacitor device obtained in Example 7;

FIG31 is a graph showing the change in specific capacity-ΔE ^* _ab -temperature of the supercapacitor device obtained in Example 7;

FIG32 is a curve showing the variation of L ^* , a ^* , and b ^* values of the Ni(OH) ₂ electrode with nickel foam as the current collector during the charge and discharge process obtained in Example 8 as a function of the charge and discharge time;

33 is a curve showing the change of L ^* , a ^* , and b ^* values of the Ni(OH) ₂ electrode with carbon paper as the current collector during the charge and discharge process obtained in Example 8 as a function of the charge and discharge time;

34 is a graph showing the charge and discharge process curves and ΔE ^* _ab -time variation curves of the Ni(OH) ₂ electrode with nickel foam as the current collector in the voltage range of 0-0.6V obtained in Example 8;

35 is a graph showing the charge and discharge process curves of the Ni(OH) ₂ electrode with carbon paper as the current collector in the voltage range of 0-0.6 V and the ΔE ^* _ab -time variation curve obtained in Example 8.

DETAILED DESCRIPTION

The present invention is further described below in conjunction with the accompanying drawings. It should be understood that these embodiments are not limitations of the invention, but are merely illustrative. Any modification or equivalent replacement of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention shall be included in the protection scope of the present invention.

The reagents or raw materials used in the present invention can be purchased through conventional channels. If there is no special explanation, the reagents or raw materials used in the present invention are used in a conventional manner in the art or in accordance with the product instructions. In addition, any method and material similar to or equal to the recorded content can be applied to the method of the present invention. The preferred implementation methods, materials and testing instruments described in the present invention are only for demonstration purposes. Now the present invention is further described according to the accompanying drawings and specific embodiments of the specification.

The color difference technology is a method of obtaining a series of color and brightness data by testing samples, and then directly observing, comparing and analyzing the obtained data, or further calculating and processing the obtained data to obtain color difference data to accurately analyze the specific degree of color and brightness changes. Although different samples may have different values of intrinsic color and brightness, the change patterns shown by the test data are consistent.

Example 1

This embodiment provides an application for detecting the operating state of a battery-type supercapacitor material Ni(OH) ₂ by using a color difference technology, comprising the following steps:

The Ni(OH) ₂ electrode material was prepared into a working electrode and placed in a traditional three-electrode test system, in which a saturated calomel electrode was used as a reference electrode, a platinum sheet was used as a counter electrode, and a 2 mol ^-1 KOH aqueous solution was used as an electrolyte.

The Blue Battery Test System was used to conduct constant current charge and discharge tests on the supercapacitor electrode material Ni(OH) ₂ using the three-electrode test system, and the color difference change test was conducted on the electrode material part of the Ni(OH) ₂ electrode using a colorimeter. The data processing process is as follows:

(1) The blue battery test system was used to test the voltage change of the Ni(OH) ₂ electrode during the charge and discharge process at a current density of 3Ag ^-1 . The results are shown in Figure 1. It can be seen that as the charging process progresses, the voltage gradually rises to 0.6V, and then gradually decreases to 0V during the discharge process. At the same time, the colorimeter was used to measure the reflected light curve of the Ni(OH) ₂ electrode at each wavelength during this process, as shown in Figure 2.

(2) Use the instrument to convert the reflected light curve into CIEXYZ tristimulus values using formula (1):

Where λ is the wavelength of equivalent monochromatic light. R(λ) and s(λ) are the reflected light spectrum of the sample and the relative spectral power distribution of the light source, respectively. and are the CIE tristimulus values x, y, and z obtained by the CIE standard observer. The X, Y, and Z values of the Ni(OH) ₂ electrode during the charge and discharge process are shown in Figure 3. It can be seen that as the charging process proceeds, while the voltage of the Ni(OH) ₂ electrode rises from 0V to 0.6V, its X, Y, and Z values gradually decrease to the minimum value; then as the discharge process proceeds, that is, when the voltage of the Ni(OH) ₂ electrode drops from 0.6V to 0V, the X, Y, and Z values gradually rise from the minimum value to the initial level. The voltage change trend and the X, Y, and Z value change trend during the entire charge and discharge process show corresponding and opposite changes, indicating that the changes in the X, Y, and Z values can well reflect the changes in voltage.

(3) After obtaining the three stimulus values of X, Y, and Z, they can be converted into color space data such as CIELAB, CIELUV, RGB, and CMYK through formulas. Based on the data of these color spaces, only the X, Y, and Z values are further processed, and they can also reflect the changes in voltage, for example:

The X, Y, and Z tristimulus values are converted to L ^* , a ^* , and b ^* data in the CIELAB color space using formulas (2) and (3) (the value range of L ^* is 0 to 100, and the value ranges of a ^* and b ^* are both -128 to +127):

Where X, Y and Z are the CIE XYZ tristimulus values of the sample. _Xn , _Yn and _Zn are the normalized CIEXYZ tristimulus values of the reference white point (under the D65 light source, the _Xn , _Yn and _Zn values are 95.047, 100 and 108.883 respectively). By taking the charge and discharge time as the horizontal axis, the L ^* , a ^* and b ^* of the sample are plotted on the same graph, as shown in Figure 4. It can be seen that as the charging process proceeds, L ^* and b ^* gradually decrease until they reach the minimum value, and then gradually rise and return to the initial level as the discharge process proceeds. This process can well correspond to the reverse trend of the charge and discharge voltage value change in Figure 1. The ^a* value changes slightly.

The X, Y, and Z tristimulus values can also be converted to the CIELUV color space through the formula, which is also a color space that is easy to convert from the CIEXYZ color space:

Y is the tristimulus value of the color sample, _Yn is the tristimulus value of the perfect diffuse reflector, _u′n and _v′n are the chromaticity coordinates of the perfect diffuse reflector. (u′, v′) are the coordinates of the unified chromaticity diagram of CIELUV (CIE 1976UCS), and the equations of u′ and v′ are as follows:

Where x and y are the chromaticity coordinates according to the 1931 CIE standard observer and coordinate system. The results are shown in Figure 5. By observing the changes in L ^* , u ^* and v ^* data, a direct connection is established between the degree of change in the color of the sample and the progress of its charge and discharge process. During the charging process, the L ^* , u ^* and v ^* values gradually decrease until they reach the minimum value, and then gradually rise back to the initial level as the discharge process proceeds. This process can also accurately correspond to the change process of the voltage value of the charge and discharge.

(4) In addition, the color data of different color spaces can also be calculated and converted to obtain the specific degree of change of the color data in a certain direction. The following provides an example of calculation and conversion:

For the CIELAB color space, the degree of change of a ^* value The degree of change in b ^* value The degree of change in L ^* value The results are shown in Figure 6. As the charging time progresses, the ΔL ^* and Δb ^* values gradually decrease, and then reach the lowest point at the end of charging; then, as the discharge process progresses, the ΔL ^* and Δb ^* values gradually increase and return to the initial level. The ^a* value changes slightly.

For the CIELUV color space, the degree of change of u ^* value v ^* The degree of change in value The degree of change in L ^* value The results are shown in Figure 7. As the charging time progresses, the ΔL ^* , Δu ^* and Δv ^* values gradually decrease and then reach the lowest point at the end of charging; then, as the discharge process progresses, the ΔL ^* , Δu ^* and Δv ^* values gradually increase and return to the initial level.

In addition, there are some formulas for calculating color difference, which can be color difference formulas specified by CIE, or color difference formulas specially specified based on usage needs. For example, for CIELAB color space, the change of color difference can be calculated by formula (6):

For the CIELUV color space, the change in color difference can be calculated using formula (7):

The results are shown in Figure 8. As can be seen, and They all increase with the increase of voltage and decrease with the decrease of voltage, which can well reflect the voltage change trend. and The changing trends of are completely consistent with the changing trends of voltage.

(5) Performing a color test on the Ni(OH) ₂ electrode at a current density of 7Ag ^-1 while performing a cyclic charge and discharge test, calculating the discharge specific capacity value in each cycle during the cyclic charge and discharge process, and extracting the maximum value of the color change of the Ni(OH) ₂ electrode material in each cycle during this process The results are shown in Figure 9. It can be seen that the discharge capacity of the Ni(OH) ₂ electrode material shows a gradually decreasing trend as the charge and discharge cycle proceeds. During this process, the change trend of the maximum value of the color difference is completely consistent with it, and also shows a downward trend.

The above results show that by testing the color data of energy storage materials or further processing the obtained color data, the obtained color change value can reflect the voltage change and capacity change during the charging and discharging process in real time, effectively and intuitively. Each physical quantity in each color space (such as X, Y, Z, L, a, b, etc.) can reflect the change trend of the voltage, current, power, capacity and other electrical signals of the electrode material to varying degrees.

Example 2

This embodiment provides an application example of real-time detection of the operating state of a lithium battery graphite negative electrode by using a color difference technology, including the following steps:

The graphite electrode material was prepared into a negative electrode sheet of a lithium-ion battery according to a conventional method, and then a button cell was assembled in a glove box using a lithium sheet as a counter electrode according to a conventional method. For easy observation, a hole with a diameter of 8 mm was punched on one side of the button cell graphite electrode material and sealed with optical glass.

The above button battery was charged and discharged at a rate of 0.6C using the Blue Electric Battery Test System, and the graphite electrode material of the above button battery was tested through the perforated electrode shell using a colorimeter. The data processing process is as follows:

(1) The voltage change of the graphite button battery during the charging and discharging process was tested using the blue battery test system. The results are shown in Figure 10. It can be seen that as the charging process progresses, the voltage gradually rises to 2V, and then gradually drops to 0V during the discharge process. At the same time, the colorimeter is used to measure the reflected light curve of the graphite electrode at each wavelength during this process, as shown in Figure 11.

(2) The reflected light curve was converted into CIEXYZ tristimulus values using the instrument through formula (1). The X, Y, and Z values of the graphite button battery during the charge and discharge process are shown in Figure 12. It can be seen that as the charging process proceeds, while the voltage of the graphite button battery rises from 0V to 2V, its X, Y, and Z values gradually rise to the maximum value; then as the discharge process proceeds, that is, when the voltage of the graphite electrode drops from 2V to 0V, the X, Y, and Z values gradually drop from the minimum value to the initial level. The voltage change trend and the X, Y, and Z value change trend during the entire charge and discharge process show a corresponding and consistent change pattern, indicating that the changes in the X, Y, and Z values can well reflect the changes in voltage.

(3) After obtaining the three stimulus values of X, Y, and Z, the three stimulus values of X, Y, and Z are converted into L ^* , a ^* , and b ^* data of the CIELAB color space by formulas (2) and (3), as shown in Figure 13. It can be seen that for graphite button batteries, the L ^* , a ^*, and b ^* data can also well reflect the trend of voltage changes. As the charging process proceeds, L ^* , a ^*, and b ^* gradually rise to the maximum value, and then gradually decrease and return to the initial level as the discharge process proceeds. This process can well correspond to the trend of voltage value changes during charging and discharging in Figure 1. It is worth noting that the degree of change of L ^* , a ^*, and b ^* varies, and the degree of change of b* is slightly smaller, but they all show a consistent upward and downward trend.

After obtaining the XYZ tristimulus values, the XYZ tristimulus values are also converted into L ^* , u ^* and v ^* data of the CIELUV color space through formulas (4) and (5), as shown in Figure 14. It can be seen that for graphite button batteries, the L ^* , u ^* and v ^* data can also well reflect the trend of voltage changes. As the charging process proceeds, L ^* , u ^* and v ^* gradually rise to the maximum value, and then gradually decrease and return to the initial level as the discharge process proceeds. This process can well correspond to the trend of voltage value changes during charging and discharging in Figure 1.

(4) In addition, the color data of different color spaces can be calculated and converted to obtain the specific degree of change of the color data in a certain direction. The following provides an example of calculation and conversion:

For the CIELAB color space, the changes in ΔL ^* , Δa ^* , and Δb ^* values are shown in Figure 15. It can be seen that as the charging process progresses, the ΔL ^* , Δa ^*, and Δb ^* values gradually increase, and then reach the highest point at the end of charging; then, as the discharge process proceeds, the ΔL ^* , Δa ^* , and Δb ^* values gradually decrease and return to the initial level. For the CIELUV color space, the changes in ΔL ^* , Δu ^* , and Δv ^* values are shown in Figure 16. As the charging time progresses, the ΔL ^* , Δu ^*, and Δv ^* values gradually increase, and then reach the highest point at the end of charging; then, as the discharge process proceeds, the ΔL ^* , Δu ^* , and Δv ^* values gradually decrease and return to the initial level.

The color difference of the data in CIELAB color space and CIELUV color space is calculated by formula (6) and (7) respectively, and the results are shown in Figure 17. It can be seen that and They all increase with the increase of voltage and decrease with the decrease of voltage, which can well reflect the voltage change trend. and The changing trends of are completely consistent with the changing trends of voltage.

(5) The graphite button cell was subjected to a cyclic charge and discharge test while the graphite electrode was subjected to a color test. The discharge specific capacity value in each cycle during the cyclic charge and discharge process was calculated, and the maximum value of the color change (i.e., color difference) of the graphite electrode material in each cycle during this process was extracted. The results are shown in FIG18. It can be seen that the discharge specific capacity shows a gradually decreasing trend as the charge and discharge cycle process proceeds. During this process, the change trend of the maximum value of the color difference is completely consistent with that of the graphite electrode material, and also shows a decreasing trend.

Example 3

This embodiment provides an application example of detecting the operating state of lithium manganese oxide (LiMn ₂ O ₄ , LMO) of a lithium battery electrode material by using a color difference technology, including the following steps:

The LMO electrode material was prepared into an electrode sheet according to the conventional method, and then a button cell was assembled in a glove box using a lithium sheet as a counter electrode according to the conventional method. For easy observation, a hole with a diameter of 8 mm was punched on one side of the electrode material of the button cell and sealed with optical glass.

The LMO button cell was charged and discharged at a rate of 0.6C using the Blue Electric Battery Test System, and the electrode material of the assembled LMO button cell was tested using a colorimeter. The data processing process is as follows:

(1) The voltage change of the LMO button battery during the charging and discharging process was tested using the Blue Battery Test System. The results are shown in Figure 19. It can be seen that as the charging process progresses, the voltage gradually rises to 4.3V, and then gradually drops to 3V during the discharge process. At the same time, the colorimeter is used to measure the reflected light curve of the LMO electrode at each wavelength during this process, as shown in Figure 20.

(2) The instrument was used to convert the reflected light curve into CIEXYZ tristimulus values using formula (1). The X, Y, and Z values of the LMO button battery during the charge and discharge process are shown in Figure 21. It can be seen that as the charging process progresses, the X, Y, and Z values gradually rise to the maximum value while the voltage rises from 3V to 4.3V; then as the discharge process progresses, that is, when the voltage drops from 4.3V to 3V, the X, Y, and Z values gradually drop from the maximum value to the initial level. The voltage change trend and the X, Y, and Z value change trend during the entire charge and discharge process show corresponding and consistent changes, indicating that the changes in the X, Y, and Z values can well reflect the changes in voltage.

(3) After obtaining the three stimulus values of X, Y, and Z, the three stimulus values of X, Y, and Z are converted into L ^* , a ^* , and b ^* data of the CIELAB color space by formulas (2) and (3), as shown in Figure 22. It can be seen that for LMO button batteries, the L ^* , a ^*, and b ^* data can also better reflect the trend of voltage changes. As the charging process proceeds, L ^* gradually rises to the maximum value, and then gradually decreases and returns to the initial level as the discharge process proceeds. This process can well correspond to the trend of the charge and discharge voltage value changes in Figure 1. The change trend of the a ^* value is completely opposite to that of L ^* , and corresponds inversely to the trend of voltage changes. The degree of change of b ^* is slightly smaller.

(4) In addition, the color data of different color spaces can be calculated and converted to obtain the specific degree of change of the color data in a certain direction. The following provides an example of calculation and conversion:

For the CIELAB color space, the changes in ΔL ^* , Δa ^*, and Δb ^* values are shown in Figure 23. It can be seen that as the charging process progresses, the ΔL ^* value gradually increases, and then reaches the highest point at the end of charging; then, as the discharge process progresses, the ΔL ^* value gradually decreases and returns to the initial level. The change trend of the Δa ^* and Δb ^* values is completely opposite to that of ΔL ^* , but the degree of change of Δb ^* is slightly smaller. The degree of change of ΔL ^* , Δa ^* , and Δb ^* varies, but they all show a consistent upward and downward trend. The color difference of the data in the CIELAB color space is calculated using formula (6), and the results are shown in Figure 24. It can be seen that It rises as the voltage rises and falls as the voltage falls, which can well reflect the voltage change trend. The changing trend of is completely consistent with that of voltage.

Example 4

This embodiment provides an application example of detecting the operating state of lithium manganese oxide (LiCoO ₂ , LCO) of a lithium battery electrode material by using a color difference technology, including the following steps:

The LCO electrode material was prepared into an electrode sheet according to the conventional method, and then a button cell was assembled in a glove box using a lithium sheet as a counter electrode according to the conventional method. For easy observation, a hole with a diameter of 8 mm was punched on one side of the electrode material of the button cell and sealed with optical glass.

The LCO button battery was charged and discharged at a rate of 0.6C using a blue battery test system, and the electrode material part of the assembled LCO button battery was tested using a colorimeter.

The voltage change of the LCO button battery during the charging and discharging process is shown in Figure 25. It can be seen that the voltage gradually rises from 2.6V to 4.2V during the charging process, and then gradually drops to 2.6V during the discharging process. At the same time, the colorimeter is used to measure the reflected light curve of the LCO electrode at each wavelength during this process. The instrument uses formula (1) to convert the reflected light curve into CIEXYZ tristimulus values, and then converts it into CIELAB color space data L ^* , a ^* and b ^* through the formula. The color difference of the data in the CIELAB color space is calculated using formula (6), and the results are shown in Figure 26. It can be seen that It rises as the voltage rises and falls as the voltage falls, which can well reflect the voltage change trend.

Example 5

This embodiment provides an application example of detecting the operating state of lithium iron phosphate (LiFePO ₄ , LFP) of a lithium battery electrode material by using a color difference technology, including the following steps:

The LFP electrode material was prepared into an electrode sheet according to the conventional method, and then a button cell was assembled in a glove box using a lithium sheet as a counter electrode according to the conventional method. For easy observation, a hole with a diameter of 8 mm was punched on one side of the electrode material of the button cell and sealed with optical glass.

The LFP button battery was charged and discharged at a rate of 0.6C using a blue battery test system, and the electrode material part of the assembled LFP button battery was tested using a colorimeter.

The voltage change results of the LFP button battery during the charging and discharging process are shown in Figure 25. It can be seen that the voltage gradually rises from 2.6 V to 3.6 V during the charging process, and then gradually drops to 2.6 V during the discharging process. At the same time, the colorimeter is used to measure the reflected light curve of the LFP electrode at each wavelength during this process. The instrument uses formula (1) to convert the reflected light curve into CIEXYZ tristimulus values, and then converts it into CIELAB color space data L ^* , a ^* and b ^* through the formula.

The color difference of the data in the CIELAB color space is calculated using formula (6), and the result is shown in Figure 28. It can be seen that It rises as the voltage rises and falls as the voltage falls, which can well reflect the voltage change trend.

Example 6

An application of detecting any area of an energy storage material by using color difference technology to distinguish between a normal area, a performance degradation area, and a completely damaged area, specifically comprising the following steps:

(1) A Co(OH) ₂ composite electrode having a normal region, a performance degradation region, and a completely damaged region is placed in a three-electrode test system, wherein the Co(OH) ₂ electrode is used as a working electrode, a saturated calomel electrode is used as a reference electrode, a platinum sheet is used as a counter electrode, and the electrolyte is a 2 mol L ^-1 KOH aqueous solution.

The above electrode materials were subjected to charge and discharge tests at a current density of 2Ag ^-1 using a blue battery test system. During this process, the normal area, performance degradation area and complete damage area of the electrode were tested using a colorimeter. The voltage curve obtained during the electrochemical test of the composite electrode corresponded to the color change curve of different areas during the charge and discharge process, as shown in FIG29.

It can be seen that for the Co(OH) ₂ composite electrode with normal area, performance degradation area and complete damage area, as the charging process progresses, the voltage gradually rises to 0.45V, and then gradually drops to 0V as the discharge process progresses. However, the degree of color change in the three areas is different. For the normal area, the color difference can be as high as 1.59, and it is higher than the other two areas during the entire charging and discharging process; the change in color difference in the performance degradation area is lower than that in the normal area; the color change in the complete damage area is basically not obvious. The above shows that the degree of color difference change can correspond well to the charging and discharging performance, and can effectively distinguish the normal area, performance degradation area and complete damage area on the same electrode.

Example 7

This embodiment provides an application example of detecting the color change of components of an energy storage device, such as a stainless steel housing, an electrode material, a diaphragm, etc., as the temperature changes by using a color difference technology, including the following steps:

(1) The ambient temperature was raised, and the color of the stainless steel shell, NiCo-LDH electrode material, and diaphragm in the non-operating state was tested to obtain the color change trend at different temperatures, as shown in Figure 30. It can be seen that as the temperature rises, the color difference of the stainless steel shell, NiCo-LDH electrode material, and diaphragm increases significantly, indicating that the color difference can well reflect the change in temperature.

(2) Using NiCo-LDH and activated carbon as electrodes and potassium hydroxide as electrolyte, a supercapacitor device was assembled using a button cell shell. For easy observation, a hole with a diameter of 8 mm was punched on one side of the electrode material of the button cell and sealed with optical glass.

The supercapacitor device was charged and discharged, and the NiCo-LDH electrode was tested for color. Then the ambient temperature was increased, and the capacity change and color change (color difference) of the device were recorded during the temperature increase. ), and the color change trend during the test at different temperatures was obtained, as shown in Figure 31. As the temperature rises, the capacity of the device gradually increases, and the color difference It also gradually increases, indicating that the color difference can well reflect the impact of temperature changes on device performance during device operation.

Example 8

This embodiment provides an application example of detecting the operating status of an energy storage device using different current collectors by using color difference technology. The research method of this embodiment is similar to that of Example 1, wherein the current collectors of the Ni(OH) ₂ electrode use foamed nickel and carbon paper respectively.

The changes in L ^* , a ^* , and b ^* values of Ni(OH) ₂ electrode materials using nickel foam and carbon paper as current collectors during a charge and discharge cycle are shown in Figures 32 and 33. It can be seen that the L ^* , a ^*, and b ^* values and the corresponding degree of change of the two are different, which shows that the color difference technology can also be used to analyze the current collector selected for the energy storage device. As the charge and discharge process proceeds, the L ^* , a ^*, and b ^* values all show a consistent trend of first rising and then falling or first falling and then rising. Calculate it and further convert the data into color difference data As shown in Figures 34 and 35, the color difference between the two Both rise, and as the discharge progresses, the color difference between the two All of them decreased, showing a consistent change pattern. This shows that despite the different current collectors, the color data can also well reflect the change trend of the electrical performance of the energy storage device.

Claims (7)

1. An application of color difference technology in detecting the status of energy storage devices, which is characterized by using a colorimeter to conduct in-situ color testing of any area of the energy storage device with changes in charge and discharge, current collector, and temperature, and perform data processing. Obtain the color data changes of the tested area of the energy storage device, so as to evaluate the state changes of any area of the energy storage device using color difference technology; The data processing process is: Use the colorimeter to detect the reflected light curve of the region at each wavelength during the state change process; Use the instrument to convert the reflected light curve obtained in step (1) into CIE tristimulus values X, Y and Z through the following formula (1): ; Among them, in formula (1), λ is the wavelength of equivalent monochromatic light; R(λ) and s(λ) are the reflected light spectrum of the sample and the relative spectral power distribution of the light source respectively; x̅(λ), y̅(λ ) and z̅(λ) are the CIE tristimulus values X, Y and Z obtained by the CIE standard observer; (3) After obtaining the tristimulus values X, Y and Z, the tristimulus values X, Y and Z can be converted into CIELAB, CIELUV, CIEUVW, YUV, HSL/HSV, RGB or CMYK color space data; The energy storage device is an energy storage device based on carrier transfer or element valence state transformation; The state change is one or more of operating/non-operating state, voltage change, capacity change, current collector change and temperature change. 2. The application according to claim 1, characterized in that the colorimeter is a spectrophotometer, a spectrophotometer type colorimeter, a photoelectric integration colorimeter, a spectral scanning colorimeter, a digital camera or Spectral imaging technology. 3. The application according to claim 1, characterized in that the method of obtaining color data changes of the tested area of the energy storage device is to use a color standard to express and record the color of the tested energy storage device in digital form. 4. The application according to claim 1, characterized in that the capacity change is one or more of stability, improvement, decline and failure of capacity. 5. The application according to claim 1, characterized in that the change of the current collector is to use different materials as the electrode current collector. 6. The application according to claim 1, characterized in that the temperature changes are temperature changes of electrodes of the energy storage device or different components of the electrolyte that can be detected by this technology. 7. The application according to claim 1, characterized in that the detection of the arbitrary area is that the color difference technology can independently conduct electrical and/or thermal properties of any area of the electrode, electrolyte and other components of the energy storage device. Performance testing.