Reference electrode for a three-electrode battery, three-electrode battery, and vehicle

Abstract

The application provides a reference electrode of a three-electrode battery, a three-electrode battery and a vehicle. The reference electrode is provided with a diaphragm between a positive electrode of the three-electrode battery and a negative electrode of the three-electrode battery; the reference electrode comprises a copper-antimony composite material, and a lithium-containing compound is deposited on the surface of the reference electrode through an alloying reaction. Thus, lithium can be fixed on the surface of the reference electrode, lithium can be uniformly deposited on the surface of the reference electrode, and the lithium is not prone to reacting with an electrolyte in a subsequent cycle process, so that the lithium deposited on the surface of the reference electrode can be effectively prevented from being destroyed, and the reference electrode can have good structural stability and potential stability.

Description

Technical Field

[0001] This invention relates to the field of batteries, and in particular to a reference electrode for a three-electrode battery, a three-electrode battery, and a vehicle. Background Technology

[0002] In the prior art, in order to eliminate the error in electrode potential caused by polarization current in a two-electrode system, a reference electrode can be introduced to stabilize the working electrode based on a conventional two-electrode system (working motor and counter electrode).

[0003] Generally, for lithium-ion batteries, a three-electrode system can be constructed by depositing lithium on the surface of copper wire as a reference electrode. However, on the one hand, the deposited lithium is prone to reacting with the electrolyte and cannot maintain a stable state during cell cycling or storage, which may lead to the failure of the three-electrode system of the lithium-ion battery in a short period of time. On the other hand, such as Figure 1 The schematic diagram shown illustrates the lithium plating process of the reference electrode. Metallic lithium is deposited onto the surface of the copper wire to complete the lithium plating. However, during the cycling process of the lithium-ion battery, the reference electrode can easily react with the electrolyte, but the lithium metal layer is destroyed, and the three-electrode system fails. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a reference electrode for a three-electrode battery, a three-electrode battery, and a vehicle, so as to maintain good stability during the cycling process of a three-electrode lithium-ion battery.

[0005] To address the aforementioned issues, this invention provides a reference electrode for a three-electrode battery. A separator is disposed between the reference electrode and the positive electrode of the three-electrode battery, and a separator is disposed between the reference electrode and the negative electrode of the three-electrode battery. The reference electrode comprises a copper-antimony composite material, and a lithium-containing compound is deposited on its surface through an alloying reaction.

[0006] Optionally, the copper-antimony composite material is prepared by at least one of the following methods: chemically depositing an antimony layer on the surface of a copper substrate, electroplating an antimony layer on the surface of a copper substrate, or vapor-depositing an antimony layer on the surface of a copper substrate.

[0007] Optionally, the thickness of the antimony layer is 1–25 μm.

[0008] Optionally, the lithium-containing compound is Li x Sb(0 <x≤3)。

[0009] Optionally, the lithium-containing compound is charged between the positive electrode and the reference electrode of the three-electrode battery using a preset charging and discharging device, so that the reference electrode and metallic lithium undergo an alloying reaction to form the lithium compound.

[0010] Optionally, the lithium-containing compound is obtained through an alloying reaction according to the following formula:

[0011]

[0012] Optionally, the surface of the copper-antimony composite material is coated with an insulating layer.

[0013] Optionally, the potential of the reference electrode is 0.8V (vs Li / Li+).

[0014] This invention also provides a three-electrode battery, comprising a reference electrode as described in this invention embodiment.

[0015] This invention also provides a vehicle comprising a three-electrode battery as described in this invention.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] The reference electrode of the three-electrode battery provided in this embodiment of the invention has a separator between it and the positive electrode of the three-electrode battery, and another separator between it and the negative electrode of the three-electrode battery. The reference electrode comprises a copper-antimony composite material, and a lithium-containing compound is deposited on its surface through an alloying reaction. This allows lithium to be effectively fixed on the surface of the reference electrode, ensuring uniform deposition and minimizing reaction with the electrolyte during subsequent cycling. This effectively prevents the lithium deposited on the reference electrode surface from being destroyed, resulting in good structural and potential stability. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a lithium plating process for a reference electrode in the prior art;

[0019] Figure 2 This is a schematic diagram of a lithium plating process for a reference electrode provided in an embodiment of the present invention. Detailed Implementation

[0020] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] This invention provides a reference electrode for a three-electrode battery. A separator is disposed between the reference electrode and the positive electrode of the three-electrode battery, and a separator is disposed between the reference electrode and the negative electrode of the three-electrode battery. The reference electrode comprises a copper-antimony composite material, and a lithium-containing compound is deposited on its surface through an alloying reaction.

[0022] Specifically, the reference electrode of the three-electrode battery provided in this embodiment of the invention has a separator between it and the positive electrode of the three-electrode battery, and a separator is also provided between it and the negative electrode of the three-electrode battery. The separator can effectively isolate the electrodes from each other, avoid internal short circuits in the three-electrode lithium-ion battery system, and ensure that the three-electrode lithium-ion battery system can operate safely.

[0023] In specific implementations, materials with good comprehensive properties such as good mechanical strength, thermal stability, and high dielectric constant can be used as diaphragms, such as diaphragms made of fluoropolymers such as polyvinylidene fluoride, ceramic-coated diaphragms, boron nitride-coated diaphragms, etc. This invention does not limit the use of such materials.

[0024] Specifically, to ensure stable lithium deposition on the reference electrode, the reference electrode can incorporate a copper-antimony composite material. During lithium plating, the antimony in the copper-antimony composite material undergoes an alloying reaction with the lithium contained in the lithium-ion battery to form a lithium-containing compound, thereby effectively fixing the lithium to the surface of the reference electrode. In this case, the lithium does not simply adhere to the surface of the reference electrode but forms an alloy phase with the antimony, effectively preventing lithium dendrite formation. During subsequent cycling, the lithium-containing chemicals in the alloy phase are less likely to react with the electrolyte, effectively preventing the lithium deposited on the reference electrode surface from being destroyed, thus exhibiting good structural and potential stability.

[0025] In one embodiment of the present invention, the copper-antimony composite material is prepared by at least one of the following methods: chemically depositing an antimony layer on the surface of a copper substrate, electroplating an antimony layer on the surface of a copper substrate, and vapor-depositing an antimony layer on the surface of a copper substrate.

[0026] Specifically, an antimony layer can be added to the surface of a copper substrate through surface chemistry, surface electroplating, or surface vapor deposition, thereby depositing antimony, which can undergo an alloying reaction with lithium, onto the surface of the copper substrate. Thus, during the subsequent alloying reaction, lithium can react with the antimony on the surface of the copper-antimony composite material to form an alloy on the surface of the copper substrate, thereby achieving lithium plating on the copper substrate surface.

[0027] As a specific example of the present invention Figure 2 This is a schematic diagram of a lithium plating process for a reference electrode according to an embodiment of the present invention. An additional antimony layer is added to the surface of the copper substrate of the reference electrode. During the lithium plating process, antimony can undergo an alloying reaction with lithium, forming a lithium-containing compound on the surface of the copper substrate. This achieves stable attachment of lithium to the surface of the copper substrate. During subsequent battery cycles, because lithium and antimony form a lithium-containing compound through the alloying reaction, lithium will not easily detach from the lithium-containing chemical. Therefore, lithium can remain relatively stably fixed on the surface of the reference electrode during the use of the lithium-ion battery, thereby enabling the reference electrode to maintain good structural and potential stability, effectively improving the safety of the lithium-ion battery.

[0028] In one embodiment of the present invention, the thickness of the antimony layer is 1 to 25 μm.

[0029] Specifically, to ensure effective lithium-ion deposition on the copper substrate surface, the antimony layer thickness can range from 1 to 25 μm. If the antimony layer is too thin, sufficient lithium may be difficult to store in the lithium-containing chemicals formed on the copper substrate surface, potentially leading to a decrease in the performance of the reference electrode. Furthermore, an excessively thin antimony layer may result in an overly thin alloy layer, affecting the stability of the reference electrode. Conversely, if the antimony layer is too thick, excessive lithium may be stored on the copper substrate surface, causing variations in the current density of the alloy layer formed on the reference electrode surface, potentially preventing the three-electrode lithium-ion battery from operating properly. A thickness of 1–25 μm for the antimony layer on the copper substrate allows for good stability of the reference electrode while maintaining a moderate current density, ensuring proper operation of the three-electrode lithium-ion battery.

[0030] In one embodiment of the present invention, the lithium-containing compound is Li x Sb(0 <x≤3)。

[0031] Specifically, lithium-containing chemicals formed by the alloying reaction of antimony and lithium can be used for Li x Sb. And 0 < x ≤ 3. Therefore, lithium can be effectively deposited on the surface of a copper substrate through an antimony layer, and because antimony and lithium form Li x Sb alloys exhibit good structural and potential stability, effectively improving the stability of the reference electrode. Furthermore, one Sb mole can form an alloy with 1 to 3 Li moles, allowing the antimony layer to efficiently store lithium on the surface of the copper substrate.

[0032] In one embodiment of the present invention, the lithium-containing compound is charged between the positive electrode and the reference electrode of the three-electrode battery using a preset charging and discharging device, so that the reference electrode and metallic lithium undergo an alloying reaction to form the lithium-containing compound.

[0033] Specifically, there are various ways to set up a reference electrode. For example, lithium metal can be directly implanted as the reference electrode, or the reference electrode can be directly assembled between the positive and negative electrodes of a lithium-ion battery. However, these methods, which directly assemble lithium metal into the lithium-ion battery as the reference electrode, have several drawbacks. First, lithium metal may still react with the electrolyte. Second, the reference electrode is relatively large, which can locally affect lithium-ion migration and shield the electric field between the positive and negative electrodes. Furthermore, these methods require operation in an inert atmosphere, making the technical solution difficult to implement. Therefore, a pre-designed charging and discharging device can be used to charge between the positive electrode and the reference electrode of the three-electrode battery, causing an alloying reaction between the reference electrode and lithium metal. Using this method to process the reference electrode can effectively control its size, minimize the impact on battery performance, and can be operated in an air environment. The alloying reaction of the reference electrode can be completed with high precision, allowing lithium metal to be deposited well on the surface of the reference electrode.

[0034] Based on electrochemical alloying reactions, lithium can diffuse into the interior of the antimony layer to form an alloy phase, which can effectively avoid dendrite formation and also form a more stable electrode / electrolyte interface.

[0035] In one embodiment of the present invention, the lithium-containing compound is obtained through an alloying reaction according to the following formula:

[0036]

[0037] Specifically, antimony on the reference electrode surface can react with metallic lithium in the lithium-ion battery to form Li. x Sb alloy. This allows the antimony layer on the reference electrode surface to have the function of storing metallic lithium, enabling metallic lithium to be deposited better on the surface of the reference electrode.

[0038] In one embodiment of the present invention, the surface of the copper-antimony composite material is covered with an insulating layer.

[0039] Specifically, the surface of the copper-antimony composite material can be coated with an insulating layer, which can minimize the contact between the electrolyte and the copper-antimony composite material, reduce the impact of the electrolyte on the lithium on the reference electrode surface, and improve the stability of the reference electrode.

[0040] Optionally, the potential of the reference electrode is 0.8V (vs Li / Li+).

[0041] Specifically, the potential of the reference electrode can be 0.8V (vs Li / Li+). In practical applications, the reference electrode can be well stabilized near this potential, maintaining the stable operation of the three-electrode system lithium-ion battery.

[0042] This invention also provides a three-electrode battery, comprising a reference electrode as described in the embodiments of this invention. The specific structure and working principle of the reference electrode have been described in detail in the foregoing embodiments and will not be repeated here.

[0043] The three-electrode battery provided in this invention has a separator between the reference electrode and the positive electrode, and another separator between the reference electrode and the negative electrode. The reference electrode comprises a copper-antimony composite material, and a lithium-containing compound is deposited on its surface through an alloying reaction. This allows for better fixation of lithium on the surface of the reference electrode, ensuring uniform deposition of lithium on the reference electrode surface. Furthermore, it minimizes the likelihood of reaction with the electrolyte during subsequent cycling, effectively preventing the destruction of the lithium deposited on the reference electrode surface, and thus exhibiting good structural and potential stability.

[0044] The three-electrode battery provided in this invention adds a reference electrode with good structural and potential stability to the lithium-ion battery. Electrode potentials can be monitored during battery charging and discharging. During charging and discharging, the relative potential changes of the positive and negative electrodes and the reference electrode can be measured separately, thereby obtaining the contribution of the positive and negative electrodes to the overall battery voltage. Simultaneously, the magnitude and causes of overpotentials in the positive and negative electrodes under different SOC conditions can be studied. Long-term monitoring is also possible to detect the causes of degradation in the positive and negative electrodes, and timely voice and control measures can be implemented to prevent more serious failures of the lithium-ion battery.

[0045] By setting a reference electrode, the fast-charging performance of the battery can be monitored, and the fast-charging boundary of the battery can be determined. The fast-charging boundary of the battery can be affected by parameters such as charging current, voltage, and temperature. Specifically, the fast-charging boundary can be determined by whether lithium plating occurs at the negative electrode during fast charging. Therefore, by setting a reference electrode, the positive and negative electrodes in the lithium-ion battery can be monitored, and the current state of the battery can be determined based on the positive and negative electrode values, ensuring that the potential of the negative electrode relative to Li / Li+ is always greater than zero, preventing lithium plating at the negative electrode and thus preventing battery performance degradation.

[0046] This invention also provides a vehicle comprising a three-electrode battery as described in this invention embodiment. The specific structure and working principle of the three-electrode battery have been described in detail in the foregoing embodiments and will not be repeated here.

[0047] The vehicle provided in this embodiment of the invention has a separator between the reference electrode and the positive electrode of the three-electrode battery, and another separator between the reference electrode and the negative electrode of the three-electrode battery. The reference electrode comprises a copper-antimony composite material, and a lithium-containing compound is deposited on its surface through an alloying reaction. This allows lithium to be effectively fixed on the surface of the reference electrode, ensuring uniform deposition and minimizing reaction with the electrolyte during subsequent cycling. This effectively prevents the lithium deposited on the reference electrode surface from being destroyed, resulting in good structural and potential stability.

[0048] The foregoing has provided a detailed description of the reference electrode, the three-electrode battery, and the vehicle provided by the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A reference electrode for a three-electrode battery, characterized in that, A separator is provided between the reference electrode and the positive electrode of the three-electrode battery, and a separator is provided between the reference electrode and the negative electrode of the three-electrode battery; the reference electrode contains a copper-antimony composite material, and a lithium-containing compound is deposited on its surface through an alloying reaction. The copper-antimony composite material is prepared by at least one of the following methods: chemically depositing an antimony layer on the surface of a copper substrate, electroplating an antimony layer on the surface of a copper substrate, and vapor-depositing an antimony layer on the surface of a copper substrate. The lithium-containing compound is obtained through an alloying reaction according to the following formula: Among them, 0 <x≤3; The antimony layer has a thickness of 1–25 μm; the copper-antimony composite material is coated with an insulating layer; the reference electrode has a potential of 0.8 V relative to Li / Li+; and the diaphragm is any one of a fluoropolymer-coated diaphragm, a ceramic-coated diaphragm, or a boron nitride-coated diaphragm.

2. The reference electrode according to claim 1, characterized in that, The lithium-containing compound is charged between the positive electrode and the reference electrode of the three-electrode battery using a preset charging and discharging device, so that the reference electrode and metallic lithium undergo an alloying reaction to form the compound.

3. A three-electrode battery, characterized in that, It includes a reference electrode as described in any one of claims 1-2.

4. A vehicle, characterized in that, It includes the three-electrode battery as described in claim 3.

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