Lithium-plated copper foil reference electrode and three-electrode lithium ion soft package battery

Abstract

The utility model discloses a lithium-plated copper foil reference electrode and three-electrode lithium ion soft package battery, relates to soft package battery technical field, including lithium-plated copper foil, welding portion and nickel-plated copper tab, the surface of nickel-plated copper tab is plated with nickel layer, the end portion of lithium-plated copper foil is provided with lithium-plated portion, the surface of lithium-plated portion is plated with lithium layer, the lithium-plated copper foil is provided with lithium layer, the welding portion is welded with the lithium layer, and the three-electrode lithium ion soft package battery is connected with the lithium-plated copper foil. And the welding part is connected with the lithium-plated copper foil and the nickel-plated copper tab. The surface of the lithium-plated copper foil reference electrode is not easy to corrode, the performance of electrolyte is not easy to influence, and the lithium-plated copper foil reference electrode is not easy to leak and fall off. The three-electrode lithium ion soft package battery comprises the lithium-plated copper foil reference electrode and comprises a positive plate, a diaphragm; a negative plate; and the lithium-plated copper foil reference electrode is in a thin foil shape and is placed between the positive plate and the negative plate, and the surface of a lithium-plated part is coated with a diaphragm. The three-electrode lithium-ion soft-package battery is uniformly stressed when being clamped by the clamping plates in a subsequent test, the performance of the battery is easy to maintain, the battery is green and environment-friendly, and the production efficiency is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of soft-pack batteries, and particularly relates to a lithium-plated copper foil reference electrode and a three-electrode lithium-ion soft-pack battery. Background Art

[0002] With the booming development of lithium battery enterprises in the new energy industry, lithium-ion batteries have been widely used in fields such as digital products, electrical appliances, and automobiles. Lithium-ion batteries, also known as secondary batteries, refer to the fact that lithium ions can be transmitted between the positive electrode and the negative electrode through charge and discharge, and the transmission rate affects the power performance of the battery. However, during the rapid charge and discharge process of the battery, the problem of lithium deposition is likely to occur, and lithium deposition is likely to pierce the separator, causing serious safety problems. Therefore, it is particularly important to screen the material system and electrochemical platform through the three-electrode method to achieve fast charging performance.

[0003] Traditional reference electrodes use copper wires or copper meshes and lithium sheets as reference electrodes, that is, copper wires or copper meshes are used as electrode tabs, and a lithium sheet or lithium plating is coated at one end of the electrode tab, and then the end with the lithium sheet or lithium plating is immersed in the battery, so as to test the potential of the positive and negative electrodes of the battery with respect to the reference electrode. However, the copper wires used in traditional reference electrodes need to be surface-treated by methods such as acid leaching. The part in contact with the electrolyte is prone to corrosion, resulting in a change in the standard potential of the reference electrode. If the copper wire after acid leaching surface treatment is not completely lithium-plated, its direct contact with the electrolyte will also affect the electrolyte. In addition, the other end of the copper wire is directly led out from the side seal, bottom seal or side top seal of the battery electrode tab on both sides, there is a risk of liquid leakage. Although directly coating the other end of the copper wire with a lithium sheet can eliminate the lithium plating step, the direct contact between the lithium sheet and the copper wire is easy to fall off and cause failure. If lithium is plated on the copper wire after assembling the battery, the required time is long and the process is cumbersome.

[0004] For example, the patent with the publication number of CN 117727854 A discloses a method for preparing a reference electrode, a reference electrode and a lithium-ion battery, which relates to the technical field of lithium-ion batteries. Specifically, it includes: taking a metal wire, removing the oxide layer on the surface of the metal wire with dilute acid; fixing both ends of the metal wire, and coating an insulating layer on the middle part of the metal wire; coating the exposed lower end of the metal wire with a lithium battery separator to form electrical insulation from the outside; placing the prepared reference electrode into an un-injected lithium-ion battery, which can be close to the positive electrode side or the negative electrode side, and the separator-coated end of the metal wire should be placed in the center of the electrode plate, and the insulating coating should exceed the packaging material, then the battery is injected with liquid and packaged; the battery is subjected to formation and grading; using the positive electrode and the negative electrode of the lithium battery as lithium sources respectively, the reference electrode is in-situ bidirectionally lithium-plated, so that lithium is evenly deposited on the metal wire.

[0005] For example, the patent with the publication number CN 106785068 A discloses a three - electrode soft - package battery and its preparation method, including a laminated battery encapsulated between an upper aluminum - plastic film and a lower aluminum - plastic film. The laminated battery includes a positive - electrode coated electrode, two separator films, and a negative - electrode coated electrode. The positive - electrode coated electrode is welded with a positive - electrode aluminum tab through a current collector, the negative - electrode coated electrode is welded with a negative - electrode nickel tab through a current collector, a copper mesh is arranged between the two separator films, and a lithium metal sheet covers the surface of one end of the copper mesh, and the other end extends out of the separator film and is connected with an auxiliary aluminum tab. Summary of the Utility Model

[0006] Technical problems to be solved by the utility model

[0007] Aiming at the technical problems that the copper wire of the traditional reference electrode needs to be surface - treated by methods such as acid leaching, which is easy to corrode and causes changes in the standard potential of the reference electrode; the copper wire after acid leaching is prone to incomplete lithium plating, affecting the performance of the electrolyte; the other end of the copper wire is directly led out from the side - seal edge, bottom - seal edge or side - top - seal edge on both sides of the battery tab, with a risk of liquid leakage; and the other end of the copper wire is directly coated with a lithium sheet, which is easy to fall off and cause failure, the utility model provides a lithium - plated copper - foil reference electrode, whose surface is not easily corroded, does not easily affect the performance of the electrolyte, is not prone to liquid leakage, and is not easy to fall off.

[0008] Aiming at the technical problems that one end of the copper wire of the traditional three - electrode lithium - ion soft - package battery is directly coated with a lithium sheet, the soft - package battery is prone to uneven stress when clamped by a splint during subsequent tests, and the copper wire needs to be surface - treated by acid leaching, which is not environmentally friendly, the utility model provides a three - electrode lithium - ion soft - package battery, which is evenly stressed when clamped by a splint during subsequent tests, is easy to maintain the battery performance, is green and environmentally friendly, and improves the production efficiency and the yield rate of the three - electrode soft - package battery.

[0009] Technical solution

[0010] To solve the above problems, the technical solution provided by the utility model is as follows:

[0011] A lithium - plated copper - foil reference electrode, including a lithium - plated copper foil, a welding part, and a nickel - plated copper tab. The surface of the nickel - plated copper tab is plated with a nickel layer. The end of the lithium - plated copper foil is provided with a lithium - plating part, and the surface of the lithium - plating part is plated with a lithium layer. The welding part connects the lithium - plated copper foil and the nickel - plated copper tab, and the nickel - plated copper tab is provided with tab glue outside.

[0012] The lithium-plated copper foil with a lithium-plated part can be directly purchased and used to prepare a reference electrode. This not only avoids treating the copper foil by methods such as acid leaching, which is environmentally friendly and fast in preparation, but also eliminates the need for further lithium plating. After preparation, it can be directly tested, saving time. The nickel-plated copper tab with tab glue can be efficiently installed on the aluminum-plastic film to ensure no liquid leakage during encapsulation. The surface of the lithium-plated copper foil is not easily corroded, does not easily affect the performance of the electrolyte, and is relatively thin. In a soft-pack battery, it does not affect the internal stress of the battery and is not prone to stress concentration when the battery is clamped, which may affect the battery performance or even cause damage.

[0013] Optionally, the thickness of the lithium-plated part is 25 - 30 μm.

[0014] Such a thickness generally does not have a significant impact on the overall structure and internal stress of the battery in the application of soft-pack batteries.

[0015] Optionally, the lithium-plated part, the welding part, and the tab glue are arranged in sequence, and the tab glue is arranged beside the welding part.

[0016] Both the lithium-plated part and the welding part are inside the aluminum-plastic film encapsulation of the battery, and the welding part is not exposed outside, ensuring that when the battery is under external pressure, the welding part will not become a stress concentration point. And the exposure of the welding part outside will affect the appearance.

[0017] Optionally, the tab glue is made of PP (polypropylene) material.

[0018] Lightweight: PP is a very light plastic, which helps to reduce the weight of the battery.

[0019] Chemical resistance: PP has good chemical corrosion resistance and can stably exist in the internal environment of the battery for a long time.

[0020] Insulation: PP has good insulation performance, which can prevent short circuits between tabs.

[0021] Temperature resistance: PP has a certain temperature resistance range and can maintain its physical properties within a certain temperature range.

[0022] Flexibility: PP has a certain flexibility, which helps to absorb the internal stress of the battery and reduce the risk of damage caused by external pressure.

[0023] A three-electrode lithium-ion soft-pack battery includes the above-mentioned lithium-plated copper foil reference electrode, and includes an aluminum-plastic film, inside which there are a positive electrode sheet, a negative electrode sheet, and a separator, connected to the tabs of the lithium-plated copper foil reference electrode, the positive electrode sheet, and the negative electrode sheet; the positive electrode sheet is connected with an aluminum tab; the separator covers the surfaces of the positive electrode sheet and the negative electrode sheet; the negative electrode sheet is connected with a nickel-plated copper tab; the lithium-plated copper foil reference electrode is in the shape of a thin foil, placed between the positive electrode sheet and the negative electrode sheet, and the surface of the lithium-plated part is covered with a separator.

[0024] Aluminum-plastic film: used to encapsulate the entire battery assembly.

[0025] Positive electrode sheet: connected with an aluminum tab, which is an electrode of the battery and is usually composed of an active material containing lithium transition metal oxide.

[0026] Separator: coated on the surfaces of the positive electrode sheet and the negative electrode sheet, used to separate the positive and negative electrodes, while allowing the free passage of lithium ions and preventing the direct flow of electrons.

[0027] Negative electrode sheet: connected with a nickel-plated copper tab, which is the other electrode of the battery and is usually composed of graphite or other lithium-ion insertion materials.

[0028] The lithium-plated copper foil reference electrode is very thin. During subsequent tests, the battery is evenly stressed by the clamping of the clamping plate, and it is easy to maintain the battery performance. The reference electrode does not need surface treatment such as pickling, and the process is green and environmentally friendly. And because the surface treatment process is reduced, the production efficiency and the yield rate of the three-electrode soft-pack battery are improved.

[0029] Optionally, the aluminum-plastic film is bonded to the tabs of the lithium-plated copper foil reference electrode, the positive electrode sheet, and the negative electrode sheet through tab glue.

[0030] Fixing function: The tab glue ensures a stable connection between the tab and the electrode, avoiding the movement of the tab during the battery assembly process.

[0031] Insulating function: The tab glue has good insulation performance and can prevent short circuits between different tabs.

[0032] Sealing function: The tab glue can also provide a certain sealing effect to help prevent electrolyte leakage.

[0033] Stress dispersion: The tab glue can also help disperse stress and reduce the influence of external pressure on the internal structure of the battery.

[0034] Optionally, the positive electrode sheet, the separator, and the negative electrode sheet form a stacked structure, and several layers of the stacked structure are provided in the aluminum-plastic film.

[0035] Stacked structure: The positive electrode sheet, the separator, and the negative electrode sheet are stacked in sequence to form a unit layer. Multiple such unit layers are stacked together to form the main body of the battery. A separator is provided between the positive electrode sheet and the negative electrode sheet in each unit layer to prevent direct contact and short circuit.

[0036] Multi-layer design: The stacked structure has several layers in the aluminum-plastic film, which means that the battery internally contains multiple positive electrode / separator / negative electrode combination layers. This multi-layer design increases the effective area of the battery and thus improves the energy density of the battery.

[0037] Improve energy density: By increasing the number of stacked layers, the energy density of the battery can be effectively improved, that is, the energy storage capacity per unit volume or weight.

[0038] Improve battery performance: The stacked structure helps to evenly distribute the pressure inside the battery, reduce stress concentration, and thus improve the stability and cycle life of the battery.

[0039] Easy to manufacture: The manufacture of the stacked structure is relatively simple, and automated equipment can be used for efficient production, which helps to improve production efficiency and reduce costs.

[0040] Optionally, two negative electrode sheets are provided for each layer of the stacked structure, clamping the positive electrode sheet in the middle, and a separator is provided between the negative electrode sheet and the aluminum-plastic film.

[0041] Balance the lithium-ion distribution: The design of clamping the positive electrode sheet with two negative electrode sheets helps to balance the lithium-ion distribution inside the battery, reduce the formation of lithium dendrites, and improve the safety of the battery.

[0042] Improve energy density: By increasing the number of stacked layers, the energy density of the battery can be effectively improved, that is, the energy storage capacity per unit volume or weight.

[0043] Improve battery performance: This structure helps to evenly distribute the pressure inside the battery, reduce stress concentration, and thus improve the stability and cycle life of the battery.

[0044] Easy to manufacture: The manufacture of the stacked structure is relatively simple, and automated equipment can be used for efficient production, which helps to improve production efficiency and reduce costs.

[0045] Beneficial effects

[0046] Adopting the technical solution provided by the present utility model, compared with the prior art, it has the following beneficial effects:

[0047] For the first technical solution provided by the present utility model, the lithium-plated copper foil reference electrode uses a lithium-plated copper foil, the surface of which is not easily corroded, does not easily affect the performance of the electrolyte, does not easily leak liquid, does not easily fall off, and a nickel-plated copper pole ear with pole ear glue is welded at the pole ear, and it is ensured that there is no liquid leakage during encapsulation.

[0048] Technical solution two provided by the present utility model, a three-electrode lithium-ion soft-pack battery, includes the lithium-plated copper foil reference electrode described above. The lithium-plated copper foil is relatively thin, and during subsequent tests, it is uniformly stressed when clamped by the clamping plate, avoiding stress concentration, easily maintaining the battery performance, without the need for pickling, being environmentally friendly, reducing processes, and improving the production efficiency and the yield rate of the three-electrode soft-pack battery. The thin lithium-plated copper foil does not affect the uneven stress caused by the clamping plate during subsequent tests of the soft-pack battery. Only need to cut the lithium-plated copper foil according to the required size, remove the copper wire by non-environmentally friendly methods such as acid immersion, the production is simple, environmentally friendly, and there is no need for surface treatment steps anymore, and it can be directly tested, saving time. Brief Description of the Drawings

[0049] Figure 1 It is a schematic structural diagram of a lithium-plated copper foil reference electrode proposed by an embodiment of the present utility model;

[0050] Figure 2 It is a front view of a three-electrode lithium-ion soft-pack battery proposed by an embodiment of the present utility model;

[0051] Figure 3 It is a side view of a three-electrode lithium-ion soft-pack battery proposed by an embodiment of the present utility model;

[0052] 1. Nickel-plated copper tab; 2. Aluminum tab; 3. Tab glue; 4. Aluminum-plastic film; 5. Separator; 6. Lithium-plated part; 7. Positive electrode sheet; 8. Negative electrode sheet; 9. Welding part. Detailed Embodiment

[0053] To further understand the content of the present utility model, the present utility model will be described in detail in combination with the drawings and embodiments.

[0054] Embodiment

[0055] Combined with the attached Figure 1 , a lithium-plated copper foil reference electrode, includes a lithium-plated copper foil, a welding part 9 and a nickel-plated copper tab 1. The surface of the nickel-plated copper tab 1 is plated with a nickel layer. The end of the lithium-plated copper foil is provided with a lithium-plated part 6. The surface of the lithium-plated part 6 is plated with a lithium layer. The welding part 9 connects the lithium-plated copper foil and the nickel-plated copper tab 1. The nickel-plated copper tab 1 is externally provided with tab glue 3.

[0056] The width of the lithium-plated part 6 is 5 - 15 mm, the length is 20 - 40 mm, and the thickness is 25 - 30 μm. In this embodiment, the width is 5, 10 or 15 mm, the length is 20, 30 or 40 mm, and the thickness is 25, 28 or 30 μm.

[0057] Furthermore, the width of the nickel-plated copper tab 1 is 10 - 80 mm, and the thickness is 0.1 - 0.5 mm;

[0058] The width of the tab glue 3 is 5 to 15 mm, and the thickness is 50 to 200 μm;

[0059] The welding area is the welding area of the lithium-plated copper foil and the nickel-plated copper tab 1, with a length of 2 to 10 mm and a width of 2 to 8 mm;

[0060] The width of the lithium-plated copper foil is 1 to 10 mm, the thickness is 5 to 30 μm, and the length is 1 to 50 mm;

[0061] The width of the lithium-plated part 6 of the lithium-plated copper foil is 1 to 10 mm, the single-sided lithium-plated thickness is 5 to 15 μm, and the length is 1 to 40 mm;

[0062] The thickness of the separator 5 is 5 to 20 μm, the width is 1 to 15 mm, and the length is 5 to 20 μm.

[0063] The lithium-plated part 6, the welding part 9, and the tab glue 3 are arranged in sequence, and the tab glue 3 is arranged beside the welding part 9.

[0064] Both the lithium-plated part 6 and the welding part 9 are inside the aluminum-plastic film 4 package of the battery, and the welding part 9 is not exposed.

[0065] The tab glue 3 is made of PP polypropylene material.

[0066] Combined with the attached Figures 2-3 A three-electrode lithium-ion soft-pack battery includes the lithium-plated copper foil reference electrode described above, and is characterized in that it includes an aluminum-plastic film 4, inside which there are a positive electrode sheet 7, a negative electrode sheet 8, and a separator 5, which are connected to the tabs of the lithium-plated copper foil reference electrode, the positive electrode sheet 7, and the negative electrode sheet 8; a positive electrode sheet 7, connected with an aluminum tab 2; a separator 5, covering the surfaces of the positive electrode sheet 7 and the negative electrode sheet 8; a negative electrode sheet 8, connected with a nickel-plated copper tab 1; the lithium-plated copper foil reference electrode, which is in the shape of a thin foil, is placed between the positive electrode sheet 7 and the negative electrode sheet 8, and the surface of the lithium-plated part 6 is covered with a separator 5.

[0067] The aluminum-plastic film 4 is bonded to the tabs of the lithium-plated copper foil reference electrode, the positive electrode sheet 7, and the negative electrode sheet 8 through the tab glue 3.

[0068] The positive electrode sheet 7, the separator 5, and the negative electrode sheet 8 form a stacked structure, and there are several layers of the stacked structure inside the aluminum-plastic film 4.

[0069] There are two negative electrode sheets 8 in each layer of the stacked structure, clamping the positive electrode sheet 7 in the middle, and there is a separator 5 between the negative electrode sheet 8 and the aluminum-plastic film 4.

[0070] Preparation method:

[0071] The lithium-plated copper foil with tabs is cut into strips with a length of 30 mm and a width of 10 mm in a glove box with a dew point below 45°C or under inert gas protection, and one end retains the tab part; the nickel-plated copper tab 1 is welded to the lithium-plated copper foil; the lithium-plated part 6 of the lithium-plated copper foil is covered with a separator 5; the positive and negative electrodes 8 that have passed the baking moisture test are stacked; the nth layer of the stack is selected, and the reference electrode is placed between the negative electrode 8 and the separator 5 to form a complete stacked structure; the stacked structure is encapsulated to obtain a three-electrode lithium-ion battery; further, n≥1; further, each layer of the stack includes a negative electrode, a separator 5, and a positive electrode 7, and the separator 5 is located between the positive electrode 7 and the negative electrode 8.

[0072] After subsequent liquid injection, the battery undergoes the normal formation and grading process; the positive and negative electrodes and the reference electrode are respectively connected to the battery test cabinet for constant current charging.

[0073] The above schematically describes the present invention and its implementation manners. This description is not restrictive, and what is shown in the drawings is only one of the implementation manners of the present invention. The actual structure is not limited thereto. Therefore, if those of ordinary skill in the art are inspired by it and, without departing from the gist of the present invention, design similar structural manners and embodiments to this technical solution without creative efforts, they shall fall within the protection scope of the present invention.

Claims

1. A lithium-plated copper foil reference electrode, characterized in that: It includes a lithium-plated copper foil, a welding part and a nickel-plated copper tab, wherein the surface of the nickel-plated copper tab is plated with a nickel layer, the end of the lithium-plated copper foil is provided with a lithium-plated part, the surface of the lithium-plated part is plated with a lithium layer, the welding part connects the lithium-plated copper foil and the nickel-plated copper tab, and the nickel-plated copper tab is provided with tab glue.

2. A lithium-plated copper foil reference electrode according to claim 1, characterized in that: The thickness of the lithium-plated portion is 25 to 30 μm.

3. A lithium-plated copper foil reference electrode according to claim 1, characterized in that: The lithium plating part, the welding part and the tab glue are arranged in sequence, and the tab glue is arranged beside the welding part.

4. A lithium-plated copper foil reference electrode according to claim 1, characterized in that: The ear glue is made of PP polypropylene.

5. A three-electrode lithium-ion soft-pack battery, comprising the lithium-plated copper foil reference electrode according to claim 2, characterized in that: include The aluminum-plastic film has a positive electrode sheet, a negative electrode sheet and a separator disposed therein, and is connected to the tabs of the lithium-plated copper foil reference electrode, the positive electrode sheet and the negative electrode sheet; A positive electrode sheet connected with an aluminum tab; A separator, coated on the surface of the positive electrode sheet and the negative electrode sheet; A negative electrode sheet connected with a nickel-plated copper lug; The lithium-plated copper foil reference electrode is in the shape of a thin foil and is placed between the positive electrode sheet and the negative electrode sheet, and the surface of the lithium-plated portion is coated with a diaphragm.

6. A three-electrode lithium-ion soft pack battery according to claim 5, characterized in that: The aluminum-plastic film is bonded to the tabs of the lithium-plated copper foil reference electrode, the positive electrode sheet and the negative electrode sheet through tab glue.

7. A three-electrode lithium-ion soft pack battery according to claim 5, characterized in that: The positive electrode sheet, the separator and the negative electrode sheet form a laminate structure, and the laminate structure is provided with a plurality of layers in the aluminum-plastic film.

8. A three-electrode lithium-ion soft pack battery according to claim 7, characterized in that: The negative electrode sheets of each layer of the laminate structure are provided with two sheets, the positive electrode sheet is clamped in the middle, and a separator is provided between the negative electrode sheet and the aluminum-plastic film.

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