A battery aging visualization method and battery cell structure

Abstract

The invention discloses a battery aging visualization method and a battery cell structure, the method comprising: adding a colored gas into an electrolyte of a battery, wherein the colored gas has a certain solubility in the electrolyte; at the beginning of the battery life, the inside of the battery is colorless; during the use of the battery, as the battery ages, the colored gas dissolved in the electrolyte is released, the color inside the battery changes, and the color inside the battery is observed through a transparent window on a battery shell to obtain the aging of the battery; based on the principle that the aging of a battery cell is related to the consumption of the electrolyte inside the battery cell, the invention adds a colored gas into the electrolyte, associates the consumption of the electrolyte with the color change of the colored gas, utilizes the color change of the colored gas to reflect the aging degree of the battery, and realizes the visualization of the battery aging through the transparent observation window, so that the aging of the battery cell can be judged intuitively by naked eye observation.

Description

Technical Field

[0001] The present invention belongs to the technical field of power batteries for electric vehicles, and in particular relates to a battery aging visualization method and a battery core structure. Background Art

[0002] The statements herein merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] As a driving force for new energy vehicles, lithium-ion batteries have been widely used in the field of new energy vehicles due to their green, recyclable, and small size. However, one of the most difficult problems with lithium-ion batteries is battery aging. When the capacity of lithium-ion batteries decays to a certain extent, the power battery is no longer suitable for use in vehicles. At present, the aging of batteries is mainly detected by BMS (battery management system) in the vehicle segment, but the maturity of the BMS model for detecting battery aging has yet to be developed, and large errors in aging estimation often occur. In addition, BMS usually makes an estimate at the whole pack level and cannot know the aging of each cell in the battery pack. Summary of the invention

[0004] The purpose of the present invention is to provide a battery aging visualization method and a battery cell structure, which can realize the visualization of battery aging and can intuitively judge the aging of the battery cell by naked eye observation.

[0005] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0006] In a first aspect, an embodiment of the present invention provides a battery aging visualization method, comprising:

[0007] Adding a colored gas to the electrolyte of the battery, wherein the colored gas has a certain solubility in the electrolyte;

[0008] At the beginning of the battery's life, the inside of the battery is colorless; during the use of the battery, as the battery ages, the colored gas dissolved in the electrolyte is released and the color inside the battery changes. The color inside the battery can be observed through the transparent window on the battery case to obtain the battery's aging condition.

[0009] As a further technical solution, the colored gas is one or a combination of nitrogen dioxide, chlorine, fluorine or ozone.

[0010] As a further technical solution, the non-colored gas is nitrogen dioxide.

[0011] As a further technical solution, the amount of colored gas added to each battery is the amount of gas that can be dissolved in the electrolyte in the battery cell.

[0012] As a further technical solution, the correspondence between the battery aging attenuation degree and the gas color is calibrated through experiments to compare and judge the real-time aging degree of the battery cell.

[0013] As a further technical solution, the battery attenuation aging degree is calibrated according to different gas colors as 0%, 10%, 20%, 30%, 40%, and 50%.

[0014] In a second aspect, in a typical embodiment of the present invention, a battery cell structure with visualized battery aging is provided, comprising a battery shell, a transparent observation window is arranged on the battery shell, a battery aging degree and color comparison card is affixed next to the transparent observation window, and the battery shell is filled with electrolyte, and colored gas is dissolved in the electrolyte.

[0015] As a further technical solution, the transparent observation window is made of transparent glass, transparent plastic or transparent quartz.

[0016] As a further technical solution, the colored gas is one or a combination of nitrogen dioxide, chlorine, fluorine or ozone. Preferably, the colored gas is nitrogen dioxide.

[0017] As a further technical solution, the corresponding relationship between the battery aging attenuation degree and the gas color is calibrated through experiments to produce an aging degree and color comparison card.

[0018] The beneficial effects of the above embodiments of the present invention are as follows:

[0019] The battery aging visualization method provided by the present invention is based on the principle that the aging of the battery cell is related to the consumption of the electrolyte inside the battery cell. By adding a colored gas to the electrolyte, the consumption of the electrolyte is associated with the color change of the colored gas. The color change of the colored gas is used to reflect the degree of battery aging. Through a transparent observation window, the battery aging is visualized, and the aging of the battery cell can be judged intuitively by naked eye observation.

[0020] The present invention provides a corresponding transparent observation window on the outer shell of each battery, so as to realize the observation of the aging condition of each battery, so as to facilitate the timely replacement of the power battery; compared with the existing method of using BMS to detect battery aging, the detection result is more intuitive and accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0022] Figure 1It is the condition of the electrolyte inside the battery at the beginning of its life;

[0023] Figure 2 It is the condition of the electrolyte inside the battery after the battery has been used for a period of time;

[0024] Figure 3 It is a schematic diagram of the overall structure of the visual battery;

[0025] Figure 4 is a schematic diagram of the transparent observation window and the comparison card;

[0026] Figure 5 It is a comparison diagram between the implementation method of Example 1 and the experiment.

[0027] The schematic diagram is for illustrative purposes only;

[0028] Among them, 1. Battery shell; 2. Battery core; 3. Colored gas dissolved in the electrolyte in the core; 4. Colored gas dissolved in the free electrolyte; 5. Free electrolyte in the battery; 6. Colored gas precipitated from the electrolyte; 7. Transparent observation window; 8. Aging degree and color comparison card. DETAILED DESCRIPTION

[0029] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0030] Example 1

[0031] In view of the problem that the existing technology cannot realize the aging condition of each battery cell in the battery pack, the inventor has found, based on actual engineering cases, that the aging of the battery cell is usually accompanied by the consumption of the electrolyte inside the battery cell. The specific process is that the electrolyte changes from the initial liquid state to the gaseous state. Due to the vaporization of the liquid electrolyte, the ion transport inside the battery cell is blocked, the impedance of the battery cell increases, and the electrical performance of the battery decreases. Therefore, the amount of liquid electrolyte retained in the battery cell can be used as a parameter to measure the degree of aging of the battery cell.

[0032] Based on the above principles, in a typical embodiment of the present invention, a battery aging visualization method is provided, comprising:

[0033] Adding a colored gas to the electrolyte of the battery, wherein the colored gas has a certain solubility in the electrolyte;

[0034] At the beginning of the battery's life, the inside of the battery is colorless; during the use of the battery, as the battery ages, the colored gas dissolved in the electrolyte is released and the color inside the battery changes. The color inside the battery can be observed through the transparent window on the battery case to obtain the battery's aging condition.

[0035] In this embodiment, the colored gas is one or a combination of nitrogen dioxide (NO2, reddish brown), chlorine (Cl2, yellowish green), fluorine (F2, light yellow) or ozone (O3, light blue). The colored gas is selected to be a colored gas that does not react with the electrolyte and has no effect on the battery performance.

[0036] Further preferably, the colored gas is nitrogen dioxide, which is reddish brown in color and is easier to distinguish than other colors.

[0037] In this embodiment, the amount of colored gas added to each battery is the amount of gas that can be dissolved in the electrolyte in the battery cell, so that the inside of the battery cell is colorless at the beginning of the life (BOL) of the battery cell. The amount of gas that can be dissolved in the electrolyte in the battery cell is tested by experiment before making the battery.

[0038] In this embodiment, the corresponding relationship between the battery aging attenuation degree and the gas color is calibrated through experiments to compare and judge the real-time aging degree of the battery cell. Specifically, during the battery cell development process, the corresponding relationship between the battery cell aging attenuation degree and the gas color is calibrated through experiments, and a comparison scale card is made and attached next to the battery cell observation window to facilitate comparison and judgment of the real-time aging degree of the battery cell.

[0039] In this embodiment, the battery attenuation aging degrees are calibrated according to different gas colors as 0%, 10%, 20%, 30%, 40%, and 50%. The lowest value is selected as 50% because once the battery life decays to 50%, it is generally considered that the battery has basically failed and has no value for subsequent use.

[0040] The battery aging visualization method provided in this embodiment has the following principles:

[0041] When the battery cell is manufactured, a colored gas is added to the electrolyte of the battery. The colored gas has a certain solubility in the electrolyte. The amount of colored gas added is just the amount of gas that can be dissolved in the electrolyte in each battery cell. In this way, at the beginning of the battery cell's life (BOL), the inside of the battery cell is colorless, such as Figure 1 As shown, the colored gas dissolved in the electrolyte includes the colored gas 3 dissolved in the electrolyte in the winding core and the colored gas 4 dissolved in the free electrolyte.

[0042] Furthermore, during the use of the battery, as the battery ages, the electrolyte inside the battery cell is continuously consumed, and due to the consumption of the electrolyte, the colored gas originally dissolved in the electrolyte is released, and the released gas fills the gap inside the battery cell, so that the aging of the battery cell can be observed through the external transparent window (the gas released from the electrolyte will be evenly distributed inside the battery cell due to the diffusion effect, and even if there is unevenness, it will gradually diffuse to homogeneity due to the principle of entropy increase). Moreover, the more the electrolyte inside the battery cell is consumed, the more gas is released, and the darker the observed color is, such as Figure 2 As shown, the colored gas 6 released from the electrolyte fills various gaps inside the battery cell.

[0043] In a specific implementation of the present embodiment, the non-colored gas is nitrogen dioxide (NO2, reddish brown). According to experiments, the solubility of NO2 in the electrolyte is that one volume of electrolyte can dissolve 0.55 volumes of NO2. In the battery manufacturing process, the injection amount of the square aluminum shell battery cell with a size of 26mm*220*90mm is 100g (80mL). Therefore, 44mL of NO2 gas is injected while the battery cell is injected, so that it just reaches saturated dissolution without excess gas overflow.

[0044] A transparent observation window 7 is left on the side shell of one side of the battery, and the window is sealed with transparent material, through which the internal conditions of the battery cell can be observed. Specifically, the transparent observation window 7 is located at 2 / 3 of the height of the side of the battery, the width of the opening is 1 / 3 of the width of the battery cell, and the material of the transparent window is transparent plastic. The inside of the battery cell observed through the observation window of a fresh battery is colorless.

[0045] The battery with colored NO2 gas pre-dissolved in the electrolyte is connected to the charge and discharge cabinet in the laboratory for accelerated cycle aging test. Through regular RPT capacity test, the color of the battery cell observed from the observation window is recorded when the battery capacity decays by 10%, 20%, 30%, 40%, and 50%. Since the battery is basically in a diving state after the capacity is lower than 50%, the color below 50% has no application value, so the color change of the battery after this stage is no longer calibrated.

[0046] The colors observed inside the battery cells at different aging and attenuation levels of the battery calibrated in the above laboratory are made into a color comparison card 8 and attached to the left side of the observation window to facilitate intuitive comparison of the real-time color and battery cell attenuation level.

[0047] In order to verify the validity of the corresponding relationship between the laboratory colored gas changes and battery aging, the experimental batteries were assembled into a battery system and operated according to the actual operating conditions of customers. Under this condition, the relationship between the color change of the gas inside the battery and the capacity attenuation was observed. The difference between the laboratory calibrated color and the actual use color is shown in Figure 5 , the calculated color difference ratio is less than 5%. This degree of error can meet the needs of engineering use, thus verifying the effectiveness of this method.

[0048] Example 2

[0049] In a typical embodiment of the present invention, a visual battery structure is provided, such as Figure 3 and Figure 4 As shown, it includes a battery shell 1, on which a transparent observation window 7 is arranged, and a battery aging degree and color comparison card 8 is attached next to the transparent observation window 7. The battery shell 1 is filled with electrolyte, and colored gas is dissolved in the electrolyte.

[0050] A transparent observation window 7 is provided on the side shell of one side of the battery, and the window is sealed with transparent material, through which the internal conditions of the battery cell can be observed. The transparent observation window 7 is specifically arranged at a position where the color of the gas inside can be theoretically seen.

[0051] In this embodiment, the transparent observation window is made of transparent glass, transparent plastic or transparent quartz. Preferably, the transparent observation window is made of transparent plastic.

[0052] In this embodiment, the colored gas is one or a combination of nitrogen dioxide, chlorine, fluorine or ozone. Preferably, the colored gas is nitrogen dioxide.

[0053] In this embodiment, the corresponding relationship between the battery aging attenuation degree and the gas color is calibrated through experiments to produce an aging degree and color comparison card.

[0054] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A battery aging visualization method, characterized in that: include: Adding a colored gas to the electrolyte of the battery, wherein the colored gas has a certain solubility in the electrolyte; At the beginning of the battery's life, the inside of the battery is colorless; during the use of the battery, as the battery ages, the colored gas dissolved in the electrolyte is released and the color inside the battery changes. The color inside the battery can be observed through the transparent window on the battery case to obtain the battery's aging condition.

2. The battery aging visualization method according to claim 1, characterized in that: The colored gas is one or a combination of nitrogen dioxide, chlorine, fluorine or ozone.

3. The battery aging visualization method according to claim 2, characterized in that: The colored gas is nitrogen dioxide.

4. The battery aging visualization method according to claim 1, characterized in that: The amount of colored gas added to each battery is the amount of gas that can be dissolved in the electrolyte in the battery cell.

5. The battery aging visualization method according to claim 1, characterized in that: Through experiments, the corresponding relationship between the battery aging and attenuation degree and the gas color is calibrated to compare and judge the real-time aging degree of the battery cell.

6. The battery aging visualization method according to claim 5, characterized in that: The battery attenuation aging degree calibrated according to different gas colors is 0%, 10%, 20%, 30%, 40%, and 50%.

7. A battery cell structure with battery aging visualization, characterized in that: The invention comprises a battery shell, wherein a transparent observation window is arranged on the battery shell, and a battery aging degree and color comparison card is attached next to the transparent observation window. The battery shell is filled with electrolyte, and colored gas is dissolved in the electrolyte.

8. The battery cell structure for visualizing battery aging as claimed in claim 7, characterized in that: The transparent observation window is made of transparent glass, transparent plastic or transparent quartz.

9. The battery cell structure for visualizing battery aging according to claim 7, characterized in that: The colored gas is one or a combination of nitrogen dioxide, chlorine, fluorine or ozone. Preferably, the colored gas is nitrogen dioxide.

10. The battery cell structure for visualizing battery aging according to claim 7, characterized in that: The corresponding relationship between the battery aging attenuation degree and the gas color is calibrated through experiments to make aging degree and color comparison cards.

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