Third electrode for removing dendrites of battery, and removing method

Abstract

The present application discloses a third electrode for removing dendrites of a battery, and a removing method. A third electrode for removing dendrites of a battery. The battery comprises a battery positive electrode, a battery electrolyte, a battery separator, and a battery negative electrode. The third electrode comprises a cavity and an electrode plate. The cavity consists of an upper cavity and a lower cavity which are communicated and can be disassembled. The upper cavity is at least provided with an opening. The battery electrolyte can flow through the cavity through the opening. The opening is made of an electrode separator. The electrode plate is mounted in the lower cavity. The lower cavity is made of an electrode insulating film. In the method provided by the present application, dendrites of a battery can be thoroughly eliminated, the service life of a battery is prolonged many times, the cost is greatly reduced, the application range is wide, and the method has good popularization and application values.

Description

Third electrode for removing battery dendrites and removal method

[0001] This application claims priority to Chinese Patent Application No. CN202410517348.1, filed on April 26, 2024, entitled “Third Electrode for Removing Battery Dendrites and Method Thereof”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of battery dendrite technology, specifically to a third electrode for removing battery dendrites and a removal method. Background Technology

[0003] Lithium dendrites refer to the unusual formation of lithium ions on the surface of a negative electrode during charging. Instead of embedding within the electrode material, lithium ions deposit as metallic lithium. This is more likely to occur during low-temperature charging, fast charging, and overcharging. The deposited metallic lithium does not form a smooth coating but exists as dendritic crystals, hence the name lithium dendrites.

[0004] Dendrite formation can lead to several problems: 1. Capacity loss: Dendrites may puncture the battery separator, causing short circuits and capacity loss. 2. Internal short circuit: Dendrites may penetrate the battery separator, causing internal short circuits, which can trigger thermal runaway and fire. 3. Reduced lifespan: Dendrite formation reduces the battery's lifespan.

[0005] Therefore, reducing dendrite formation or removing existing dendrites is of great significance for improving battery performance and safety. Summary of the Invention

[0006] Therefore, this application provides a third electrode for removing battery dendrites and a method for doing so.

[0007] To achieve the above objectives, this application provides the following technical solution:

[0008] In a first aspect, a third electrode for removing battery dendrites is provided, the battery comprising a positive electrode, a battery electrolyte, a battery separator, and a battery negative electrode, the third electrode comprising a cavity and an electrode plate; the cavity comprises a connected and detachable upper cavity and a lower cavity, the upper cavity having at least one opening through which the battery electrolyte flows into the cavity, the opening being made of an electrode separator, and an electrode plate being installed in the lower cavity, the lower cavity being made of an electrode insulating film.

[0009] Preferably, the battery dendrites include lithium dendrites in lithium batteries, sodium dendrites in sodium batteries, or iron dendrites in lithium iron phosphate batteries.

[0010] Preferably, the electrode plate is made of the same material as the negative electrode of the battery, and the electrode separator is made of the same material as the battery separator.

[0011] Preferably, an opening is provided on the inner wall of the upper cavity.

[0012] In a second aspect, a circuit for removing battery dendrites includes: a third electrode as described in any of the preceding claims, a DC power supply, and a control switch, wherein the control switch is used to control the on / off state of the circuit, the positive terminal of the DC power supply is connected to the negative terminal of the battery, and the negative terminal of the DC power supply is connected to the electrode plate of the third electrode.

[0013] Thirdly, a method for clearing battery dendrites based on the circuit described above, the method comprising:

[0014] After the battery is fully discharged and all loads are disconnected, the third electrode is installed between the battery separator and the negative electrode, ensuring that the opening of the third electrode is immersed in the battery electrolyte. The control switch is then closed, and the dendrites attached to the negative electrode dissolve in the battery electrolyte. Under the action of the electric field, they pass through the opening and reach the electrode plate, becoming new dendrites that attach to the electrode plate.

[0015] Preferably, the voltage of the DC power supply is 3.7V.

[0016] Preferably, the battery negative electrode is divided into a wetted section and a dry section, and the negative electrode lead is disposed at the end of the dry section. The wetted section is immersed in the battery electrolyte, and the dry section is exposed and does not come into contact with the battery electrolyte.

[0017] Preferably, the method further includes: removing the lower cavity of the third electrode and removing the dendrites attached to the electrode plate.

[0018] Preferably, the method further includes: opening the opening on the inner wall of the cavity of the third electrode to replenish the battery with electrolyte and lithium ions.

[0019] Compared with the prior art, this application has at least the following beneficial effects:

[0020] 1. Completely eliminate lithium dendrites and prevent fires caused by spontaneous combustion of lithium batteries.

[0021] Spontaneous combustion is the most fatal flaw of lithium batteries, and lithium dendrites are the root cause of spontaneous combustion. The method described in this application can completely eliminate spontaneous combustion of lithium batteries.

[0022] 2. Extends the lifespan of lithium batteries many times over, ensuring that the lithium batteries have the same lifespan as the devices that use them.

[0023] Currently, the biggest disadvantage of electric vehicles compared to gasoline vehicles in terms of operating costs is the short lifespan of their batteries, which typically last only three to four years, or even five to six years, before becoming unusable. This significantly limits the widespread adoption of electric vehicles. The first method of this technology to extend the lifespan of lithium batteries is to have the control system completely discharge the battery and disconnect all loads before each or several charging cycles. Then, the control switch is closed, and the third electrode power supply begins to operate, thoroughly removing lithium dendrites from the negative electrode of the lithium battery. The entire cleaning process is completed automatically by the system. The second method involves performing two procedures on the entire vehicle battery after a relatively long period of use (e.g., three to five years for an electric vehicle battery): "removing lithium dendrites from the third electrode plate" and "replenishing the lithium battery electrolyte and lithium ions." Specifically, the lower part of the third electrode (the lower part of the red dotted line in Figure 1) is removed, the lithium dendrites attached to the third electrode plate are removed, and then electrolyte and lithium ions are replenished into the lithium battery through the opened upper part of the third electrode. The two methods described above can be repeated multiple times, and it is entirely possible to ensure that the lithium battery has the same lifespan as the device that uses it (such as an electric vehicle).

[0024] 3. This method makes existing liquid lithium batteries more cost-effective than future solid-state lithium batteries.

[0025] While future solid-state lithium batteries offer advantages such as high energy density and high safety and reliability, their cost is many times higher than that of equivalent liquid lithium batteries, and the technology is still not mature. Using the method described in this application, the lifespan of liquid lithium batteries will be significantly extended, and their operating costs will be greatly reduced, making them a viable replacement for solid-state lithium batteries.

[0026] 4. This method can also be used to remove lithium dendrites from solid-state batteries.

[0027] Solid-state batteries can also produce lithium dendrites, and this method can also remove lithium dendrites from solid-state batteries. Attached Figure Description

[0028] To more intuitively illustrate the prior art and this application, exemplary drawings are provided below. It should be understood that the specific shapes and structures shown in the drawings should not generally be regarded as limiting conditions for implementing this application; for example, based on the technical concept disclosed in this application and the exemplary drawings, those skilled in the art are able to easily make conventional adjustments or further optimizations to the addition / reduction / classification, specific shapes, positional relationships, connection methods, size ratios, etc. of certain units (components).

[0029] Figure 1 is a schematic diagram of the third electrode;

[0030] Figure 2 is a schematic diagram of the structure in which the third electrode is mounted on the battery;

[0031] Figure 3 is a schematic diagram of the third electrode removing cell dendrites;

[0032] Figure 4 is a schematic diagram of the battery negative electrode;

[0033] Figure 5 shows the relationship between the internal resistance of a lithium battery and time. Detailed Implementation

[0034] The present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] In the description of this application: unless otherwise stated, "a plurality of" means two or more. The terms "first," "second," "third," etc., in this application are intended to distinguish the objects referred to and do not have any special meaning in terms of technical connotation (e.g., they should not be construed as an emphasis on importance or order). Expressions such as "comprising," "including," and "having" also mean "not limited to" (certain units, components, materials, steps, etc.).

[0036] The terms used in this application, such as "upper," "lower," "left," "right," and "middle," are generally used to indicate the general relative positional relationship for the purpose of intuitive understanding by referring to the accompanying drawings, and are not absolute limitations on the positional relationship in the actual product.

[0037] Battery dendrites include dendrites generated in various batteries, such as lithium dendrites in lithium-ion batteries, sodium dendrites in sodium-ion batteries, and iron dendrites in lithium iron phosphate batteries. This includes not only liquid batteries but also solid-state batteries. This application uses lithium dendrites in liquid lithium-ion batteries as an example for illustration.

[0038] Example 1

[0039] This embodiment provides a third electrode for removing lithium dendrites from a lithium battery. Referring to Figure 1, the third electrode includes a cavity, a third electrode plate, and leads. Wherein:

[0040] The cavity consists of an upper cavity and a lower cavity that are connected. The upper cavity and the lower cavity can be integrally formed or connected by a freely detachable method. As an example, the upper cavity and the lower cavity are connected by a conventional threaded connection in the art. By providing an internal thread on the inner side of the lower end of the upper cavity and an external thread on the outer side of the upper end of the lower cavity that matches the internal thread, the upper cavity and the lower cavity can be freely detached.

[0041] The upper cavity has at least one opening through which the lithium battery electrolyte flows into the cavity. This opening is made of a third electrode separator. The third electrode separator can be made of commonly used lithium battery separator materials, such as woven membranes, non-woven membranes (non-woven fabrics), microporous membranes, composite membranes, separator paper, and rolled membranes. More preferably, the other parts of the upper cavity, excluding the opening, are made of an electrode insulating membrane. The electrode insulating membrane primarily provides insulation and is generally made of polymers or other highly insulating materials, such as polypropylene (PP), polyethylene (PE), polyester (PET), and other materials. Further preferably, the inner wall of the upper cavity also has an opening that can be freely closed or opened, through which electrolyte and lithium ions can be replenished into the lithium battery.

[0042] The lower cavity is made of a third electrode insulating film, which is impermeable to the electrolyte. The function of this film is to contain lithium atoms attached to the negative electrode, preventing them from diffusing outside the third electrode. For example, it can be made of polypropylene (PP), polyethylene (PE), polyester (PET), or other materials. The lower cavity contains a third electrode plate and leads. The leads are located at the ends of the third electrode plate and are used to connect it to other components. The materials of the third electrode plate and leads are identical to those of the lithium battery negative electrode and leads. In some specific embodiments, both the third electrode plate and the lithium battery negative electrode are graphite. The function of the third electrode plate is to allow lithium atoms to attach and form new lithium dendrites.

[0043] Example 2

[0044] This embodiment provides a circuit for removing lithium dendrites from a lithium battery. Referring to Figure 2, the circuit includes a third electrode, a negative terminal of the lithium battery, a DC power supply for the third electrode, and a control switch for the third electrode, all connected by wires. The control switch for the third electrode is used to control the on / off state of the circuit. The positive terminal of the DC power supply for the third electrode is connected to the negative terminal of the lithium battery, and the negative terminal of the DC power supply for the third electrode is connected to a lead at the end of the third electrode plate.

[0045] The installation method for the above circuit is as follows:

[0046] The third electrode is installed between the lithium battery separator and the negative electrode of the lithium battery, and the upper cavity of the third electrode is immersed in the electrolyte of the lithium battery. Specifically, the opening of the upper cavity is completely immersed in the electrolyte to ensure that the electrolyte is connected between the lithium battery and the third electrode. In some preferred embodiments, the voltage of the DC power supply for the third electrode is 3.7V.

[0047] Example 3

[0048] This embodiment provides a method for removing lithium dendrites from lithium batteries:

[0049] After the battery is fully discharged and all loads are disconnected, install the third electrode between the battery separator and the negative electrode, ensuring that the opening of the third electrode cavity is immersed in the battery electrolyte. Close the third electrode control switch. After the lithium battery is fully discharged and all loads are disconnected, close the DC power supply to the third electrode. Lithium atoms (lithium dendrites) attached to the negative electrode of the lithium battery lose an electron, becoming positively charged lithium ions, which dissolve in the electrolyte and pass through the third electrode separator under the influence of the electric field to reach the third electrode plate. The lithium ions gain an electron on the third electrode plate, becoming lithium atoms (new lithium dendrites), which then attach to the third electrode plate. The reaction formula is as follows:

[0050] On the negative electrode of a lithium battery:

[0051] Li-e=Li + (A lithium atom loses an electron to become a lithium ion)

[0052] On the third electrode plate:

[0053] Li + +e = Li (The lithium ion gains an electron and becomes a lithium atom)

[0054] This process involves transferring lithium dendrites from the negative electrode of a lithium battery to the plate of the third electrode.

[0055] When the volume of lithium dendrites attached to the third electrode plate exceeds a certain amount, the lower cavity of the third electrode (the lower part of the red dotted line in Figure 1) can be easily removed, the lithium dendrites attached to the third electrode plate can be cleaned off, and then it can be reinstalled in its original position. Alternatively, this part can be replaced. Since the negative electrode material of lithium batteries is graphite, this method will not damage the negative electrode of lithium batteries.

[0056] Before reinstalling the lower cavity of the third electrode, the electrolyte and lithium ions of the lithium battery can be replenished by opening the opening on the inner wall of the upper cavity of the third electrode.

[0057] This method can also remove dendrites from various batteries, such as iron dendrites in lithium iron phosphate batteries and sodium dendrites in sodium batteries.

[0058] The third electrode is located in the lower cavity (red dashed line), which acts as a container for storing lithium dendrites. Each lithium battery can be fitted with one or more of these containers as needed.

[0059] In some preferred embodiments, the majority of the negative electrode of the lithium battery (the portion below the white dashed line in Figure 4) is immersed in the electrolyte, referred to as the wetted section. A small portion (the portion above the white dashed line in Figure 4) is exposed and not in contact with the electrolyte, referred to as the dry section, and the negative electrode lead of the lithium battery is connected to the dry section. The dry section is provided to isolate the negative electrode lead from the electrolyte. During the lithium dendrite removal operation, the negative electrode of the lithium battery is positively charged. If the metal negative electrode lead is in direct contact with the electrolyte, the metal atoms in the lead (usually copper or lead) will be ionized into positively charged metal ions, which will enter the electrolyte, contaminating both the electrolyte and corroding the negative electrode lead.

[0060] Test case

[0061] Tests for removing lithium dendrites

[0062] 1. Parameters of the test equipment:

[0063] Lithium battery type: polymer lithium battery; lithium battery voltage: 3.7V; lithium battery capacity: 10000mAh; lithium battery internal resistance: 46mΩ; lithium battery negative electrode area: 10cm × 94cm = 940cm² 2 The area of ​​the electrode plate in contact with the negative electrode of the lithium battery is: 1cm × 94cm = 94cm² 2 The DC power supply voltage for the third electrode is 3.7V. Each test uses 22 lithium batteries. The test is repeated 20 times, with each test using brand new lithium batteries of the same model from the same manufacturer.

[0064] 2. Artificial formation of lithium dendrites

[0065] After repeated tests, all 22 lithium batteries were slightly bulged after being charged with 4.2V DC at 0℃ for 5 minutes. Upon disassembling two of them, large areas of lithium dendrite deposition were found on the negative electrode plate.

[0066] 3. Lithium dendrite removal test

[0067] Completely discharge the lithium battery and disconnect all loads. Install the third electrode between the negative electrode and the separator of the lithium battery as shown in Figure 2. Close the third electrode control switch and measure the internal resistance of the lithium battery every 3 minutes. Take the average of 20 data points to obtain the following curve. Compare the capacity of each battery before and after removing lithium dendrites. After removing the lithium dendrites, the capacity of the lithium batteries recovered to 99.86% of its original value. After each experiment, disassemble five lithium batteries for observation; all lithium dendrites on the negative electrode plate of the lithium battery had disappeared.

[0068] The technical features of the above embodiments can be combined in any way (as long as there is no contradiction in the combination of these technical features). For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described; these embodiments not explicitly written should also be considered to be within the scope of this specification.

Claims

1. A third electrode for removing battery dendrites, the battery comprising a positive electrode, a battery electrolyte, a battery separator, and a battery negative electrode, characterized in that, The third electrode includes a cavity and an electrode plate; the cavity is composed of an upper cavity and a lower cavity that are connected and detachable, the upper cavity has at least one opening, through which the battery electrolyte can flow with the cavity, the opening is made of an electrode diaphragm, and the lower cavity is equipped with an electrode plate, the lower cavity being made of an electrode insulating film.

2. The third electrode for removing battery dendrites according to claim 1, characterized in that, The battery dendrites include lithium dendrites in lithium batteries, sodium dendrites in sodium batteries, or iron dendrites in lithium iron phosphate batteries.

3. The third electrode for removing battery dendrites according to claim 1, characterized in that, The electrode plates are made of the same material as the negative electrode of the battery, and the electrode separator is made of the same material as the battery separator.

4. The third electrode for removing battery dendrites according to claim 1, characterized in that, An opening is provided on the inner wall of the upper cavity.

5. A circuit for clearing battery dendrites, characterized in that, The circuit includes: The third electrode, DC power supply, and control switch as described in any one of claims 1-4, wherein the control switch is used to control the on / off state of the circuit, the positive terminal of the DC power supply is connected to the negative terminal of the battery, and the negative terminal of the DC power supply is connected to the electrode plate of the third electrode.

6. A method for clearing battery dendrites based on the circuit of claim 5, characterized in that, The method includes: After the battery is fully discharged and all loads are disconnected, the third electrode is installed between the battery separator and the negative electrode, ensuring that the opening of the third electrode is immersed in the battery electrolyte. The control switch is then closed, and the dendrites attached to the negative electrode dissolve in the battery electrolyte. Under the action of the electric field, they pass through the opening and reach the electrode plate, becoming new dendrites that attach to the electrode plate.

7. The method according to claim 6, characterized in that, The voltage of the DC power supply is 3.7V.

8. The method according to claim 6, characterized in that, The battery negative electrode is divided into a wetted section and a dry section, and the negative electrode lead is located at the end of the dry section. The wetted section is immersed in the battery electrolyte, while the dry section is exposed and does not come into contact with the battery electrolyte.

9. The method according to claim 6, characterized in that, The method further includes: removing the lower cavity of the third electrode and removing the dendrites attached to the electrode plate.

10. The method according to claim 9, characterized in that, The method further includes: opening the opening on the inner wall of the cavity of the third electrode to replenish the battery with electrolyte and lithium ions.

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