Positive and negative pole pieces of polymer lithium ion winding battery

Abstract

The invention provides a positive and negative pole piece of a polymer lithium ion winding battery, the positive and negative pole piece comprises a positive pole piece and a negative pole piece, the positive pole piece comprises a positive current collector, a positive tab, an A dressing area, a C dressing area, an E dressing area, an F dressing area, a B empty foil area, a D empty foil area, a G empty foil area and an H empty foil area, and the positive tab is arranged in the B empty foil area; the negative electrode plate comprises a negative electrode current collector, a negative electrode tab, a dressing area a, a dressing area c, a dressing area d, a dressing area f, an empty foil area b, an empty foil area e, an empty foil area g and an empty foil area h, a single surface of the negative electrode current collector comprises an upper coating area and a lower coating area, the empty foil area h is reserved at one end of the negative electrode current collector, the negative electrode tab is arranged in the empty foil area b, and the upper coating area and the lower coating area are arranged on the other end of the negative electrode current collector. According to the invention, the problem of stability of high-rate cycle performance of a winding system lithium ion battery with a traditional pole piece structure can be solved.

Description

Technical Field

[0001] This invention belongs to the field of lithium battery electrode technology, specifically relating to positive and negative electrode sheets for a polymer lithium-ion wound battery. Background Technology

[0002] Polymer lithium-ion wound batteries consist of a positive electrode (such as lithium cobalt oxide or ternary material coated with aluminum foil), a negative electrode (such as graphite coated with copper foil), a porous separator, and a gel / solid polymer electrolyte. They are formed into cylindrical or flat electrode groups by tightly winding and encapsulated with a lightweight aluminum-plastic film.

[0003] The rate performance of polymer lithium-ion batteries is affected by internal resistance. The lower the internal resistance, the less energy is wasted by the battery, which helps with heat generation and rate performance. Reducing the internal resistance of the battery can improve the discharge rate and cycle life of lithium-ion batteries.

[0004] Reducing battery internal resistance starts with modifying the cell design to improve the discharge rate, cycle life, and other performance characteristics of lithium-ion batteries. In existing polymer lithium-ion battery designs, the tabs are welded to the head of the electrode, resulting in a long ion movement path from the tail to the head of the tab. This increases the resistance to lithium-ion movement, leading to greater polarization and higher internal resistance. Consequently, this affects the stability of high-rate cycle performance, including internal resistance stability, 3.4V plateau efficiency, and high-rate discharge performance. As a result, the battery can hardly be used for extended periods of charging and discharging under high-rate conditions (generally above 1C is considered high-rate). Summary of the Invention

[0005] To overcome the problems in the prior art, this invention develops a positive and negative electrode sheet for a polymer lithium-ion wound battery, solving the stability problem of high-rate cycle performance in traditional wound lithium-ion batteries with electrode structures.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution: A positive and negative electrode sheet for a polymer lithium-ion wound battery includes a positive electrode sheet and a negative electrode sheet. The positive electrode sheet includes a positive current collector, a positive electrode tab, an A coating area, a C coating area, an E coating area, an F coating area, a B empty foil area, a D empty foil area, a G empty foil area, and an H empty foil area. One side of the positive current collector includes an upper coating area and a lower coating area. One end of the positive current collector retains the H empty foil area. The upper coating area connected to the H empty foil area is sequentially provided with the G empty foil area, the A coating area, the B empty foil area, and the C coating area. The lower coating area connected to the H empty foil area is sequentially provided with the E coating area, the D empty foil area, and the F coating area. The positive electrode tab is located in the B empty foil area. The distance between the positive electrode tab and the A coating area is 3-6 mm. The negative electrode sheet includes a negative current collector, a negative electrode tab, a coating area, a coating area, a coating area, a coating area, a coating area, a coating area, a coating area, a blank foil area, a blank foil area, a blank foil area, a blank foil area, and a blank foil area. The negative current collector has an upper coating area and a lower coating area on one side, and a blank foil area (h) is retained at one end of the negative current collector. The upper coating area connected to the blank foil area (h) is provided with the a coating area, the b blank foil area, and the c coating area in sequence. The lower coating area connected to the blank foil area (h) is provided with the d coating area, the e blank foil area, the f coating area, and the g blank foil area in sequence. The negative electrode tab is located in the b blank foil area.

[0007] Furthermore, the positive current collector is an aluminum foil with a length of 1482mm ± 0.012mm, a width of 59mm, and a weight of 2.77 ± 0.05g, and the negative current collector is a copper foil with a length of 1560mm ± 0.006mm, a width of 60.5mm, and a weight of 5.05g ± 0.05g.

[0008] Furthermore, the positive electrode tab is an aluminum-to-nickel aluminum electrode tab ultrasonically welded to the positive electrode current collector, with a length of 56mm±1mm, a width of 6mm±1mm, and a thickness of 0.08mm±0.001mm; the negative electrode tab is a nickel electrode tab ultrasonically welded to the negative electrode current collector, with a length of 46mm±1mm, a width of 6mm±1mm, and a thickness of 0.08mm±0.001mm.

[0009] Furthermore, the dressings coated in dressing areas A, C, E, and F are either ternary or lithium cobalt oxide dressings; the dressings coated in dressing areas a, b, and c are graphite dressings.

[0010] Further, the length of the H empty foil area is 15mm, the length of the G empty foil area is 56±1mm, the length of the A dressing area is 642±1mm, the length of the B empty foil area is 163±1mm, the length of the C dressing area is 606±1mm, the length of the E dressing area is 698±1mm, the length of the D empty foil area is 54±1mm, and the length of the F dressing area is 714±1mm; the length of the h empty foil area is 15mm, the length of the a dressing area is 788±1mm, the length of the b empty foil area is 14±1mm, the length of the c dressing area is 743±1mm, the length of the d dressing area is 697±1mm, the length of the e empty foil area is 106±1mm, the length of the f dressing area is 622±1mm, and the length of the g empty foil area is 122±1mm. The coating width of the dressing area on the positive electrode current collector and the negative electrode current collector is consistent with the width of the positive electrode current collector.

[0011] Furthermore, the areal density of the double-sided dressing for the positive electrode current collector is 367±5 g / m². 2 The areal density of the double-sided dressing for the negative electrode current collector is 201 ± 3.07 g / m³. 2 .

[0012] The beneficial effects of this invention are: This application optimizes the positive and negative electrode structures of polymer lithium-ion wound batteries by reducing the travel distance between the tail of the electrode and the tab, adjusting the travel distance from the electrode coating to the spot welding point, and connecting electrodes of the same length from the middle with the tab. The travel distance from the tail of the electrode to the tab on both sides is shorter than before, resulting in a smaller battery polarization reaction, a shorter ion movement path, and lower internal resistance. This improves high-rate cycle performance and makes the discharge effect superior to batteries with traditional electrode structures. Under approximately the same discharge current, the discharge utilization rate is higher, and the internal resistance is effectively reduced, improving the stability of the battery's high-rate cycle performance. Attached Figure Description

[0013] Figure 1 This is a structural diagram of the positive electrode sheet of the present invention; Figure 2 This is a structural diagram of the negative electrode sheet of the present invention. Detailed Implementation

[0014] To make the objectives, technical solutions, and beneficial effects of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, so as to facilitate understanding by those skilled in the art.

[0015] Positive and negative electrode structures of this invention See Figure 1 A positive electrode sheet for a polymer lithium-ion wound battery, wherein the positive current collector is aluminum foil with an extended length of 1482 mm, a width of 59 mm, and a weight of 2.77 g; the lengths of the H empty foil area are 15 mm, the G empty foil area is 56 mm, the A coating area is 642 mm, the B empty foil area is 163 mm, the C coating area is 606 mm, the E coating area is 698 mm, the D empty foil area is 54 mm, and the F coating area is 714 mm.

[0016] The dressing in the positive electrode dressing area is a ternary dressing, and the areal density of the current collector on both sides is 367 g / m³. 2 .

[0017] The positive electrode tab is made of aluminum-to-nickel aluminum and welded to the positive current collector. It is 56mm long, 6mm wide, and 0.08mm thick.

[0018] See Figure 2A negative electrode sheet for a polymer lithium-ion wound battery, wherein the negative electrode current collector is aluminum foil, which has an extended length of 1560 mm, a width of 60.5 mm, and a weight of 5.05 g. The length of the empty foil area h is 15 mm, the length of the coated area a is 788 mm, the length of the empty foil area b is 14 mm, the length of the coated area c is 743 mm, the length of the coated area d is 697 mm, the length of the empty foil area e is 106 mm, the length of the coated area f is 622 mm, and the length of the empty foil area g is 122 mm.

[0019] The negative electrode dressing is a graphite dressing, and the double-sided surface density of the current collector is 201 g / m³. 2 .

[0020] The negative electrode tab is a nickel electrode tab welded to the negative electrode current collector, with a length of 46mm, a width of 6mm, and a thickness of 0.08mm.

[0021] Performance testing The positive and negative electrode sheets of the present invention and conventional end tab electrode sheets were used to prepare lithium-ion wound batteries with specifications of PC785767HS-5000mAh0.2C / 4.4V, and their performance was tested and compared. The core winding scheme of the positive and negative electrode sheet structure of the present invention is P1, and the core winding structure scheme of the conventional end tab positive and negative electrode sheets is P2.

[0022] Both methods tested the capacity, internal resistance, cycle life, and rate capability of two sample cells. The specific test methods and data are as follows: Test Example 1 I. Test objective: To detect the 300-cycle data of polymer lithium-ion wound batteries.

[0023] II. Test Products: 1. P1: 240815-A PC785767HS-5000mAh 5.2A charge / discharge 4.4V 2. P2: 240813-C PC785767HS-5000mAh 5.2A charge / discharge 4.4V III. Testing Instruments: Xinwei testing cabinet, battery internal resistance tester, digital caliper.

[0024] IV. Test conditions: ambient temperature (25℃±2℃), ambient pressure (86kPa—106kPa), relative humidity (45%±20%).

[0025] V. Test Procedures: 1. Charge at a constant current of 5.2A until the voltage reaches 4.4V; 2. Charge at a constant voltage of 4.4V until the current is 0.02C; 3. Let it stand for 5 minutes; 4. Discharge at a constant current of 5.2A until the voltage reaches 3.0V; 5. Repeat cycle 1 to 300 times to complete the experiment. (See Luffy Enterprise Standard: "Polymer Lithium-ion Battery Testing Standard").

[0026] VI. Judgment Criteria: Capacity retention ≥ 83%, internal resistance ≤ 150%, thickness ≤ 110%.

[0027] VII. Test Data: Table 1. 300-cycle test data table As shown in Table 1 of Test Example 1, after 300 cycles, the internal resistance change rate of the P1 scheme battery is 27.1%, which is much lower than the 35.9% of the conventional structure P2 scheme battery. The battery thickness change rate is also lower than that of the P2 scheme battery, while the capacity retention rate is the same as that of the P2 scheme battery. The positive and negative electrode sheets of the present invention, when used to prepare lithium-ion wound batteries, have better stability over long-term use compared to the P2 scheme battery.

[0028] Table 2 Cyclic Performance Data Table According to Table 2 of Test Example 1, the internal resistance of the P1 solution battery is 17.4-17.7Ω, which is smaller than that of the P2 solution. The high-rate discharge performance is maintained at 95.55%-99.66%, which is more stable. The efficiency of the 3.4V platform is maintained at 86%-93%, which is better than that of the P1 solution.

[0029] Test Example 2 I. Test Objective: To detect the rate capability data of polymer lithium-ion wound batteries.

[0030] II. Test Product: Same as Test Example 1 III. Testing Instrument: Xinwei Testing Instrument.

[0031] IV. Test conditions: Temperature: 25±2℃; Humidity: 45±20%; Atmospheric pressure: 86-106KPa.

[0032] V. Test Procedures: 1. When charging at a constant current of 0.5C5A to a voltage of 4.4V, switch to constant voltage charging and stop charging when the current is less than 0.01C5A; 2. Discharge at currents of 0.2C / 0.5C / 1.0C / 2.0C respectively until the termination voltage of 3.0V is reached, thus concluding the experiment.

[0033] VI. Judgment Criteria: 0.2C: 100%, 0.5C: 95%, 1.0C: 90%, 2C: 80%.

[0034] VII. Test Data: Table 3. Discharge performance test data at high rates As shown in Table 1 of Test Example 2, the rate performance of the P1 scheme battery under 2C conditions is 89.71%-91.36%, while that of the P2 scheme is only 63.97%-64.54%. The positive and negative electrode sheets of the present invention are used to prepare lithium-ion wound batteries with better high-rate discharge performance than the P2 scheme battery with traditional electrode structure.

[0035] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of the present invention.

Claims

1. A positive and negative electrode sheet for a polymer lithium-ion wound battery, characterized in that: It includes a positive electrode and a negative electrode. The positive electrode includes a positive current collector, a positive electrode tab, an A-coating area, a C-coating area, an E-coating area, an F-coating area, a B-empty foil area, a D-empty foil area, a G-empty foil area, and an H-empty foil area. One end of the positive current collector retains the H-empty foil area. Behind the H-empty foil area on one side of the positive current collector are the G-empty foil area, the A-coating area, the B-empty foil area, and the C-coating area in sequence. Behind the H-empty foil area on the other side of the positive current collector are the E-coating area, the D-empty foil area, and the F-coating area in sequence. The positive electrode tab is located in the B-empty foil area. The negative electrode sheet includes a negative current collector, a negative electrode tab, a dressing area, a dressing area, a dressing area, a dressing area, a dressing area, a dressing area, a dressing area, a blank foil area, a blank foil area, a blank foil area, a blank foil area, and a blank foil area. One end of the negative current collector retains the blank foil area h. On one side of the negative current collector, behind the blank foil area h, the dressing areas a, b, and c are arranged in sequence. On the other side of the negative current collector, behind the blank foil area h, the dressing areas d, e, f, and g are arranged in sequence. The negative electrode tab is located in the blank foil area b.

2. The positive and negative electrode sheets of the polymer lithium-ion wound battery according to claim 1, characterized in that: The positive current collector is an aluminum foil with a length of 1482 mm, a width of 59 mm, and a weight of 2.77 g. The negative current collector is a copper foil with a length of 1560 mm, a width of 60.5 mm, and a weight of 5.05 g.

3. The positive and negative electrode sheets of the polymer lithium-ion wound battery according to claim 1, characterized in that: The positive electrode tab is an aluminum-to-nickel aluminum electrode tab welded to the positive current collector, with a length of 56mm, a width of 6mm, and a thickness of 0.08mm; the negative electrode tab is a nickel electrode tab welded to the negative current collector, with a length of 46mm, a width of 6mm, and a thickness of 0.08mm.

4. The positive and negative electrode sheets of the polymer lithium-ion wound battery according to claim 1, characterized in that: The dressings coated in dressing areas A, C, E, and F are one or more of lithium manganese oxide, ternary or lithium cobalt oxide dressings; the dressings coated in dressing areas a, b, and c are one or more of artificial graphite, composite graphite, and silicon carbide.

5. The positive and negative electrode sheets of the polymer lithium-ion wound battery according to claim 1, characterized in that: The length of the H empty foil area is 15mm, the length of the G empty foil area is 56mm, the length of the A dressing area is 642mm, the length of the B empty foil area is 163mm, the length of the C dressing area is 606mm, the length of the E dressing area is 698mm, the length of the D empty foil area is 54mm, and the length of the F dressing area is 714mm; the length of the h empty foil area is 15mm, the length of the a dressing area is 788mm, the length of the b empty foil area is 14mm, the length of the c dressing area is 743mm, the length of the d dressing area is 697mm, the length of the e empty foil area is 106mm, the length of the f dressing area is 622mm, and the length of the g empty foil area is 122mm.

6. The positive and negative electrode sheets of the polymer lithium-ion wound battery according to claim 1, characterized in that: The areal density of the double-sided dressing for the positive electrode current collector is 367 g / m³. 2 The areal density of the double-sided dressing for the negative electrode current collector is 201 g / m³. 2 .

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