Lithium ion battery

Abstract

The utility model discloses a lithium ion battery, relates to the battery field, the specific implementation scheme is that: the lithium ion battery includes a shell and a roll core arranged in the shell, the roll core includes a roll core body, a positive pole lug, a negative pole lug and a third electrode, one end of the positive pole lug and one end of the negative pole lug both extend into the shell and are connected with the roll core body, and the third electrode is connected with the shell. The third electrode is attached to the outermost layer of the roll core body in a winding mode. An ampere meter is connected in series in the loop to monitor current, and a voltmeter is connected in parallel to monitor voltage, so that the lithium supplementing amount is quantitatively determined; the battery cell can be connected with the positive electrode lug and the third electrode to form a primary battery for supplementing active lithium, and a primary battery loop is disconnected immediately after the lithium supplementing amount meeting the requirement is achieved. The lithium sheet is flush with the bottom of the roll core body, so that the deformation of the roll core body in the subsequent manufacturing process can be reduced, the battery thickness is reduced, and the energy density is improved; uneven stress in the roll core body is reduced, the internal resistance is reduced, the lithium precipitation phenomenon is reduced, and the safety performance of the battery is improved.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and in particular to a lithium-ion battery. Background Technology

[0002] Unprecedented global warming and the depletion of fossil fuels have increased the demand for renewable, clean, and efficient energy, further promoting the development of energy storage systems. Since Sony Corporation of Japan introduced a commercial battery with LiCoO2 as the positive electrode and coke as the negative electrode in 1991, rechargeable lithium-ion batteries (LIBs) have become one of the most widely used electrochemical energy storage systems in portable devices and electric vehicles due to their advantages such as high energy density, high operating voltage, no memory effect, strong adaptability to high and low temperatures, and environmental friendliness. However, current technologies can only replenish active lithium in a single cycle and cannot replenish lithium uniformly and controllably, resulting in a decrease in the initial efficiency and energy density of lithium-ion batteries. Utility Model Content

[0003] Based on this, the present invention provides a lithium-ion battery to solve the problem that existing technologies can only replenish active lithium once and cannot replenish lithium evenly and controllably.

[0004] This utility model provides a lithium-ion battery, including: a housing and a core disposed inside the housing. The core includes a core body, a positive electrode tab, a negative electrode tab, and a third electrode. One end of the positive electrode tab and the negative electrode tab both extend into the housing and are connected to the core body. The third electrode is attached to the outermost layer of the core body in a wound manner.

[0005] The third electrode is attached to the outermost layer of the core body in a winding manner, which can reduce the space occupied and meet the lithium replenishment requirements.

[0006] The third electrode includes a lithium sheet, a copper sheet, and a third electrode tab. The lithium sheet is wrapped around the outermost layer of the core body. One end of the copper sheet is tightly bonded to one end of the lithium sheet by pressing. The other end of the copper sheet extends out of the housing and connects to the third electrode tab.

[0007] The lithium sheet is a rectangle with a thickness of 0.1~1mm, a width of 10~50mm, and a length of 100~500mm, and the lithium sheet is flush with the bottom of the core body.

[0008] The copper sheet has a thickness of 0.05~0.2mm and a width of 5~20mm, the third electrode tab has a thickness of 0.2~0.4mm and a width of 3~10mm, and the third electrode tab is ultrasonically welded to the copper sheet.

[0009] The third electrode tab is perpendicular to both the positive electrode tab and the negative electrode tab.

[0010] The third electrode is connected to the positive and negative electrodes via a conductive cable. The conductive cable and the third electrode are electrically connected by welding. The connection and disconnection of the conductive cable and the positive and negative electrodes are controlled by a conductive clamp.

[0011] The negative electrode tab and the third electrode tab are electrically connected to both sides of the appliance to form a primary battery circuit; an ammeter for monitoring current is connected in series in the primary battery circuit, and a voltmeter for monitoring voltage is also connected in parallel in the primary battery circuit.

[0012] The electrical appliance in the primary battery circuit is a small light bulb with a power of 0.1 to 15W.

[0013] Beneficial effects: An ammeter is connected in series in the circuit to monitor the current, and a voltmeter is connected in parallel to monitor the voltage, so as to quantitatively determine the amount of lithium to be added; after the first lithium addition, the cell is subjected to capacity testing to obtain a finished cell that meets the requirements. After long-term operation, the cell can be connected to the positive electrode and the third electrode to form a primary cell to replenish active lithium. Once the required amount of lithium to be added is reached, the primary cell circuit can be disconnected.

[0014] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this utility model, nor is it intended to limit the scope of this utility model. Other features of this utility model will become readily apparent from the following description. Attached Figure Description

[0015] The accompanying drawings are provided for a better understanding of this solution and do not constitute a limitation on this utility model. Wherein:

[0016] Figure 1 This is a schematic diagram of the three-electrode structure provided by this utility model;

[0017] Figure 2 This is a schematic diagram of a lithium-ion battery structure provided by this utility model;

[0018] Figure 3 The graph is a line graph after the embodiments and comparative examples provided by this utility model are completed. Detailed Implementation

[0019] The following description, in conjunction with the accompanying drawings, illustrates exemplary embodiments of the present invention, including various details to aid understanding. These embodiments should be considered merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present invention. Similarly, for clarity and brevity, descriptions of well-known functions and structures are omitted in the following description.

[0020] like Figure 1 , Figure 2 As shown, this utility model provides a lithium-ion battery, including: a housing 1 and a core disposed inside the housing 1. The core includes a core body 2, a positive electrode tab 3, a negative electrode tab 4, and a third electrode 5. One end of the positive electrode tab 3 and the negative electrode tab 4 extends into the housing 1 and is connected to the core body 2. The third electrode 5 is attached to the outermost layer of the core body 2 in a winding manner.

[0021] The third electrode 5 includes a lithium sheet 5a, a copper sheet 5b, and a third electrode tab 5c. The lithium sheet 5a is wrapped around the outermost layer of the core body 2. One end of the copper sheet 5b is tightly bonded to one end of the lithium sheet 5a by pressing. The other end of the copper sheet 5b extends out of the housing 1 and is connected to the third electrode tab 5c.

[0022] The lithium sheet 5a is a rectangle with a thickness of 0.1~1mm, a width of 10~50mm, and a length of 100~500mm, and the lithium sheet 5a is flush with the bottom of the core body 2.

[0023] When the lithium sheet 5a is flush with the bottom of the core body 2, the deformation of the core body 2 during subsequent manufacturing processes can be reduced, thereby reducing the battery thickness and increasing the energy density; it also helps to reduce the uneven stress inside the core body 2, thereby reducing the occurrence of side reactions inside the battery, reducing internal resistance, reducing lithium plating, and improving the safety performance of the battery.

[0024] The copper sheet 5b has a thickness of 0.05~0.2mm and a width of 5~20mm, and the third electrode tab 5c has a thickness of 0.2~0.4mm and a width of 3~10mm. The third electrode tab 5c and the copper sheet 5b are ultrasonically welded.

[0025] Ultrasonic welding, on the other hand, completes the welding process by using heat generated through vibration and friction, thus avoiding this type of damage and ensuring the quality and performance of the third electrode tab 5c.

[0026] The third electrode tab 5c is perpendicular to both the positive electrode tab 3 and the negative electrode tab 4.

[0027] The third electrode tab 5c is perpendicular to the positive electrode tab 3 and the negative electrode tab 4, which helps the current to flow more directly and evenly through the electrodes, reduces resistance, lowers the internal resistance of the battery, thereby reducing the temperature rise of the battery during high-rate discharge and improving the rate performance of the battery.

[0028] The third electrode 5 is connected to the positive electrode tab 3 and the negative electrode tab 4 via a conductive cable. The conductive cable and the third electrode 5 are electrically connected by welding. The conductive cable and the positive electrode tab 3 and the negative electrode tab 4 are connected and disconnected by a conductive clamp.

[0029] The negative electrode tab 4 and the third electrode tab 5c are electrically connected to both sides of the appliance to form a primary battery circuit. An ammeter for monitoring the current is connected in series in the primary battery circuit, and a voltmeter for monitoring the voltage is also connected in parallel in the primary battery circuit.

[0030] When replenishing active lithium before formation, the amount of lithium replenishment should be controlled to be less than 6% of the cell's design capacity. This ensures that the overall cell product does not experience excessive active lithium deposition during the first charge, which can significantly improve the initial energy density of the cell product.

[0031] When replenishing active lithium before formation, monitor the potential and ensure that the time for the galvanic cell potential to be greater than 2.0V is less than 48 hours to avoid damage to the negative electrode tab 4.

[0032] An ammeter is connected in series in the circuit to monitor the current, and a voltmeter is connected in parallel to monitor the voltage, so as to quantitatively determine the amount of lithium to be added. After the initial lithium addition, the cell is subjected to capacity testing to obtain a finished cell that meets the requirements. After long-term operation, the cell can be connected to the positive electrode and the third electrode 5 to form a galvanic cell for replenishment of active lithium. Once the required amount of lithium to be added is reached, the galvanic cell circuit can be disconnected.

[0033] The electrical appliance in the primary battery circuit is a small light bulb of 0.1~15W, which can be used to identify whether lithium replenishment is in progress.

[0034] This invention enables the replenishment of active lithium under varying SOH (State of Health, often used to indicate the remaining lifespan of a battery) conditions, with controllable and uniform lithium replenishment. Furthermore, it eliminates the need for additional devices for lithium replenishment; replenishment only requires connecting the negative electrode tab 4 to the third electrode 5 or the positive electrode tab 3 to the third electrode 5 in the original battery circuit. This solution can also be easily implemented within a battery pack. The ability to replenish active lithium under varying SOH conditions not only compensates for lithium loss during the initial charging process due to the formation of the SEI (Solid Electrolyte Interface) film, but also replenishes lithium loss caused by SEI film damage and regeneration throughout the battery's lifespan. Controllable lithium replenishment is achieved through the monitoring of capacity and voltage using voltmeters and ammeters. The integral of the current flowing through the original battery over time represents the replenishment capacity. The voltmeter accurately identifies the initial negative electrode potential, limiting its residence time at high potential to prevent damage to the negative electrode.

[0035] Example: Using lithium iron phosphate as the positive electrode and graphite as the negative electrode, after mixing and laminating, a 30A LFP / C dry cell with dimensions of 72*155*237 is obtained. A lithium sheet 5a with a thickness of 0.5mm, a width of 25mm, and a length of 150mm is wound and attached to the outermost layer of the core body 2. The core body 2 is pulled out by a copper sheet 5b. The above system is encapsulated with an aluminum-plastic film, and then injected with electrolyte to obtain the pre-formation cell. The galvanic cell circuit between the third electrode 5 and the negative electrode tab 4 is closed, and the integral value of the current over time is read. When it reaches 1Ah, the galvanic cell circuit is disconnected. After formation and capacity testing, the finished cell is obtained. After 1C / 1C cycling for 1000 cycles, the galvanic cell circuit between the third electrode 5 and the positive electrode tab 3 is closed, and the integral value of the current over time is read. When it reaches 1Ah, the galvanic cell circuit is disconnected. It is then cycled again for 1000 cycles.

[0036] Comparative Example: Using lithium iron phosphate as the positive electrode and graphite as the negative electrode, after mixing and laminating, a 30A LFP / C dry cell with dimensions of 72*155*237 was obtained. The above system was encapsulated with aluminum-plastic film, and then after liquid injection and formation capacity testing, the finished cell was obtained. It was then cycled 2000 times at 1C / 1C.

[0037] Table 1 shows a comparison of short parameter data and interface of the battery cells during the manufacturing process and after production of the embodiment and the comparative example. The lithium content before formation of the embodiment is one order of magnitude higher than that of the comparative example, the first efficiency is 3.5% higher, the energy density is 5.7Wh / kg higher, and the interface of the fully charged disassembly is uniform with no lithium plating. This indicates that the lithium-ion battery proposed in this invention has uniform lithium replenishment and no concentrated lithium replenishment occurs.

[0038] Table 1: Comparison of parameters between lithium-added and un-lithium-added battery cells

[0039] Lithium content in the anode before formation / ppm First-time effect / % Energy density Wh / kg Fully charged disassembly interface Example 2297.5 95.2 191 Uniform interface, no lithium plating Comparative Example 178.4 91.7 185.3 Uniform interface, no lithium plating

[0040] like Figure 3 The data shown are from the embodiment and the comparative example after they were taken offline. The capacity retention curves of the two cells basically overlapped during the first 1000 cycles, indicating that the device placed inside the cell had little effect on the cycle. After 1000 cycles, the capacity retention of the cell in the embodiment, after being replenished with active lithium, showed a jump, indicating that the lithium-ion battery provided by this invention has a significant lithium replenishment effect and can still effectively cycle for 1000 cycles after the lithium replenishment is completed.

[0041] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any changes or substitutions within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the protection scope of the claims.

Claims

1. A lithium-ion battery, characterized by, The application relates to a battery, which comprises a shell and a winding core arranged in the shell, wherein the winding core comprises a winding core body, a positive electrode tab, a negative electrode tab and a third electrode, one end of the positive electrode tab and the negative electrode tab is connected with the winding core body, and the third electrode is attached to the outermost layer of the winding core body in a winding mode.

2. The lithium-ion battery of claim 1, wherein: The third electrode comprises a lithium sheet, a copper sheet and a third electrode tab, the lithium sheet is attached to the outermost layer of the winding core body in a winding mode, one end of the copper sheet is closely attached to one end of the lithium sheet in a pressing and bonding mode, and the other end of the copper sheet is connected with the third electrode tab and extends out of the shell.

3. The lithium-ion battery of claim 2, wherein: The lithium sheet is rectangular with a thickness of 0.1-1 mm, a width of 10-50 mm and a length of 100-500 mm, and the lithium sheet is flush with the bottom of the winding core body.

4. The lithium-ion battery according to claim 2 or 3, characterized in that: The copper sheet has a thickness of 0.05-0.2 mm and a width of 5-20 mm, the third electrode tab has a thickness of 0.2-0.4 mm and a width of 3-10 mm, and the third electrode tab is ultrasonically welded with the copper sheet.

5. The lithium-ion battery of claim 4, wherein: The third electrode tab is perpendicular to the positive electrode tab and the negative electrode tab.

6. The lithium-ion battery of claim 4, wherein: The third electrode is connected with the positive electrode tab and the negative electrode tab through a conductive flat cable, the conductive flat cable is electrically connected with the third electrode through welding, and the conductive flat cable is connected with and disconnected from the positive electrode tab and the negative electrode tab through a conductive clamp.

7. The lithium-ion battery of claim 6, wherein: The negative electrode tab and the third electrode tab are respectively electrically connected on both sides of an electric appliance to form a primary battery circuit, a current meter for monitoring current is connected in series in the primary battery circuit, and a voltmeter for monitoring voltage is connected in parallel in the primary battery circuit.

8. The lithium-ion battery of claim 7, wherein: The electric appliance of the primary battery circuit is a small bulb with a power of 0.1-15 W.

Images