Multi-pole ear lithium-sodium composite battery and current collector plate thereof

Abstract

The application discloses a multi-pole ear lithium-sodium composite battery and a current collecting disc thereof, the composite battery is composed of a tubular sodium ion battery on the outer side and a cylindrical lithium ion battery on the inner side, high safety of the sodium ion battery and excellent charge-discharge performance at low temperature are exerted, meanwhile, use of the internal lithium ion battery guarantees high energy density of the battery. The lithium ion battery and the sodium ion battery are both designed as multi-pole ears, compared with a single-pole ear structure, the battery has lower internal resistance, and heat generation during use is significantly reduced. The current on the sodium ion battery can be conducted to the positive terminal of the lithium ion battery through the current collecting disc, so that the internal resistance of the composite battery is smaller. In a low-temperature environment, the sodium ion battery can be started first, and the lithium ion battery is started after reaching the optimal working temperature of the lithium ion battery, so that the battery performance at low temperature is improved and the service life of the battery is prolonged. The composite battery has the characteristics of strong environmental temperature adaptability, high safety and high cycle life.

Description

Technical Field

[0001] This invention belongs to the field of secondary battery technology, specifically relating to a multi-tab lithium-sodium composite battery and its current collector. Background Technology

[0002] Lithium-ion batteries are widely used in electric vehicles due to their high energy density. With the increasing number of users and the wider range of applications, the safety and low-temperature adaptability of lithium batteries have received considerable attention. The performance of lithium-ion batteries is significantly affected by low temperatures, mainly manifested in reduced discharge capacity, increased internal resistance, decreased charge / discharge efficiency, and increased side reactions. For example, at -20℃, the discharge capacity of a lithium-ion battery is only about 40% of that at room temperature. Meanwhile, sodium-ion batteries have been found to have certain advantages in terms of safety. Due to the larger radius of sodium ions, they are relatively more stable and less prone to dendrite growth problems common in lithium-ion batteries, thus reducing battery damage and safety risks. Sodium-ion batteries perform well in safety tests such as overcharge, over-discharge, short circuit, nail penetration, and crushing, and are less prone to fire and explosion. Furthermore, sodium-ion batteries have a wider operating temperature range, functioning normally in the range of -40℃ to 80℃, and retain nearly 90% of their capacity at -20℃, which is superior to lithium batteries.

[0003] A major safety concern with lithium-ion batteries is the risk of thermal runaway. Thermal runaway is a serious safety issue involving a rapid increase in internal battery temperature, leading to a series of irreversible failures such as capacity decay, battery deformation / rupture, and fire. Controlling internal resistance and reducing heat generated during battery operation are the most effective measures to prevent thermal runaway. Increased internal resistance generates significant Joule heat, causing the battery temperature to rise, resulting in a decrease in discharge voltage and a shortened discharge time, severely impacting battery performance and lifespan. Excessive internal resistance can lead to heat accumulation that, upon reaching a certain threshold, may cause a series of problems, including battery combustion and explosion. Summary of the Invention

[0004] This invention provides a multi-tab lithium-sodium composite battery and its current collector. The multi-tab lithium-sodium composite battery has the characteristics of more stable structure, higher cell strength, lower internal resistance, higher efficiency, better low temperature adaptability, more uniform heat dissipation, less prone to explosion, and higher safety.

[0005] To achieve the above objectives, the present invention adopts the following specific technical solution:

[0006] This invention provides a multi-tab lithium-sodium composite battery, comprising a tubular sodium-ion battery, a cylindrical lithium-ion battery, and a current collector; the sodium-ion battery is coaxially mounted on the outer periphery of the lithium-ion battery; the sodium-ion battery and the lithium-ion battery are connected in parallel and can be charged and discharged independently; the lithium-ion battery is used for energy storage and maintaining the operating voltage; the sodium-ion battery is used to provide temperature control assistance for the energy storage of the lithium-ion battery and can prevent the lithium-ion battery from exploding;

[0007] The lithium-ion battery has a positive terminal and a negative terminal; the positive terminals of both the sodium-ion battery and the lithium-ion battery adopt a multi-tab structure; the current collector is welded to the tabs of the sodium-ion battery and the lithium-ion battery.

[0008] Furthermore, the sodium-ion battery has multiple tabs evenly distributed circumferentially at its top.

[0009] The outer periphery of the current collector is provided with a shovel-shaped structure corresponding one-to-one with the tabs of the sodium-ion battery, and a protrusion is provided in the center.

[0010] The shovel-shaped structure is welded to the corresponding tab; the internal cavity of the boss is larger than the positive terminal of the lithium-ion battery, and is welded to the tab of the lithium-ion battery and fitted onto the positive terminal of the lithium-ion battery.

[0011] Furthermore, both the shovel-shaped structure and the boss are provided with welding gaps for welding the connecting tabs.

[0012] Furthermore, the sodium-ion battery and the lithium-ion battery are in contact via a circumferential surface.

[0013] Furthermore, a liquid cooling system is arranged between the lithium-ion battery and the sodium-ion battery.

[0014] Furthermore, both the sodium-ion battery and the lithium-ion battery are manufactured using a battery winding process.

[0015] Furthermore, the inner peripheral casing of the sodium-ion battery and the outer peripheral casing of the lithium-ion battery share the same casing.

[0016] Furthermore, the manufacturing method of the positive electrode sheet of the sodium-ion battery and the lithium-ion battery is as follows: the positive electrode material is mixed with a conductive agent and a binder and then coated onto an aluminum foil current collector, dried, and then compacted.

[0017] The manufacturing method of the negative electrode sheet of the sodium-ion battery and the lithium-ion battery is as follows: the negative electrode material is mixed with a conductive agent and a binder and then coated onto a copper foil current collector, dried and compacted.

[0018] Furthermore, the conductive agent is carbon black, etc.; the binder is polyvinylidene fluoride (PVDF), etc.

[0019] The positive electrode material of the lithium-ion battery is selected from one or more of lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, nickel cobalt manganese, nickel cobalt aluminum, lithium iron phosphate, lithium-rich manganese-based materials, layered lithium nickel oxide, and lithium manganese oxide.

[0020] The positive electrode material of the sodium-ion battery is selected from one or more of the following: metal oxides, polyanionic compounds, Prussian blue compounds, phosphate compounds, and Prussian white compounds.

[0021] The negative electrode material of the lithium-ion battery and the sodium-ion battery is selected from one or more of the following: natural graphite, artificial graphite, mesophase carbon microspheres, soft carbon, hard carbon, graphene, silicon-based materials and their composite materials.

[0022] Furthermore, the outer diameter of the sodium-ion battery is 18mm-100mm;

[0023] The outer diameter of the lithium-ion battery is 15mm-90mm;

[0024] The height of both the sodium-ion battery and the lithium-ion battery is 40mm-200mm.

[0025] In addition, the present invention also provides a current collector for the above-mentioned multi-tab lithium-sodium composite battery, wherein the outer periphery of the current collector is provided with a shovel-shaped structure corresponding one-to-one with the tabs of the sodium-ion battery, and a boss is provided in the center.

[0026] The shovel-shaped structure is used for welding connection with the corresponding electrode tab;

[0027] The internal cavity of the boss is larger than the positive terminal of the lithium-ion battery, and it is welded to the tab of the lithium-ion battery and fitted onto the positive terminal of the lithium-ion battery.

[0028] Furthermore, both the shovel-shaped structure and the boss are provided with welding gaps for welding the connecting tabs.

[0029] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0030] The multi-tab lithium-sodium composite battery of the present invention is composed of a central cylindrical lithium-ion battery and an outer tubular sodium-ion battery, which fully utilizes the high safety and excellent low-temperature charge-discharge performance of sodium-ion batteries, as well as the high energy density of lithium-ion batteries. Simultaneously, the positive electrodes of both the sodium-ion and lithium-ion batteries adopt a multi-tab structure and are welded to the current collector. Compared to a single-tab structure, this battery has lower internal resistance and significantly reduces heat generation during use. The sodium-ion and lithium-ion batteries are connected in parallel and can be charged and discharged independently. The sodium-ion battery provides temperature-controlled auxiliary energy storage for the lithium-ion battery and, together with the current collector, can prevent the lithium-ion battery from exploding. The composite battery with the above structure has the characteristics of greater structural stability under external force conditions, higher cell strength, lower internal resistance, better low-temperature adaptability, more uniform heat dissipation, less susceptibility to explosion, and better safety.

[0031] The aforementioned multi-tab lithium-sodium composite battery can be used as a vehicle power battery and is suitable for electric vehicles and other fields. Attached Figure Description

[0032] Figure 1 This is a three-dimensional structural diagram of the multi-tab lithium-sodium composite battery of the present invention;

[0033] Figure 2 This is a schematic diagram of the assembly structure of lithium-ion batteries and sodium-ion battery cells.

[0034] Figure 3 This is a schematic diagram of the collector plate.

[0035] Among them, 1-sodium ion battery, 2-tab, 3-lithium ion battery, 4-positive terminal, 5-liquid cooling system, 6-shovel-shaped structure, 7-first weld, 8-protrusion, 9-second weld. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] This invention provides a multi-tab lithium-sodium composite battery, such as... Figure 1As shown in the structure, the composite battery includes a tubular sodium-ion battery 1, a cylindrical lithium-ion battery 3, and a current collector; the sodium-ion battery 1 is coaxially mounted on the outer periphery of the lithium-ion battery 3; the sodium-ion battery 1 and the lithium-ion battery 3 are connected in parallel and can be charged and discharged independently; the sodium-ion battery 1 and the lithium-ion battery 3 have independent battery management systems, which can charge and discharge the sodium-ion battery 1 and the lithium-ion battery 3 separately; the lithium-ion battery 3 is used for energy storage and to maintain the working voltage of the entire composite battery; the sodium-ion battery 1 is much smaller in volume than the lithium-ion battery 3, and the sodium-ion battery 1 is used to provide temperature control assistance for the lithium-ion battery 3 to store energy, and can prevent further losses caused by the explosion of the lithium-ion battery 3 in the event of thermal runaway.

[0038] The lithium-ion battery 3 has a positive terminal 4 and a negative terminal; both the sodium-ion battery 1 and the lithium-ion battery 3 use a multi-tab structure for their positive electrodes; the current collector is welded to the tabs 2 of the sodium-ion battery 1 and the lithium-ion battery 3. The sodium-ion battery 1 does not have a positive terminal 4; its positive current is led out through the current collector to the positive terminal 4 of the lithium-ion battery 3, and the battery is controlled by the battery management system. The sodium-ion battery 1 and the lithium-ion battery 3 each have only one positive terminal 4, which is welded to the current collector and outputs current. The current collector of the lithium-ion battery 3 connects the current of the lithium-ion battery 3 to the positive terminal 4, and the current collector of the sodium-ion battery 1 connects the positive current of the sodium-ion battery 1 to the positive terminal 4 of the lithium-ion battery 3.

[0039] The temperature control management strategy of this composite battery is as follows: in a low-temperature environment, the sodium-ion battery 1 discharges first to heat the lithium-ion battery 3, so that it reaches the optimal operating temperature before starting the lithium-ion battery 3.

[0040] In the above-mentioned composite batteries, such as Figure 2As shown, the top of the sodium-ion battery 1 has multiple tabs 2 evenly distributed circumferentially. The outer periphery of the current collector has shovel-shaped structures 6 corresponding to the tabs 2 of the sodium-ion battery 1, with a boss 8 at its center. Multiple flat shovel-shaped structures 6 are evenly distributed around the outer periphery of the current collector; each flat shovel-shaped structure 6 is connected to the current collector at only one end, with the other parts separate to provide tolerance compensation during welding. The shovel-shaped structures 6 are welded to their corresponding tabs 2. The current collector has a boss 8 in the middle, with the interior of the boss 8 forming a cavity to accommodate the positive terminal 4 of the lithium-ion battery 3. The internal cavity of the boss 8 is slightly larger than the positive terminal 4 of the lithium-ion battery 3, allowing it to fit snugly onto the positive terminal 4 and be welded to the tab of the lithium-ion battery 3. The boss 8 can be circular, with the internal cavity diameter larger than the diameter of the positive terminal 4. This current collector can directly conduct the current from the positive tab 2 of the sodium-ion battery 1 to the positive terminal 4 of the lithium-ion battery 3 by welding it to the tabs. This current collector can collect the current from sodium-ion battery 1 and channel it to the positive terminal 4 of lithium-ion battery 3, facilitating unified management by the battery management system.

[0041] Using the aforementioned current collector can reduce the internal resistance of the battery cell and reduce battery heat generation.

[0042] To facilitate the connection between the current collector and the lithium-ion battery 3 and the sodium-ion battery 1, both the shovel-shaped structure 6 and the boss 8 are provided with welding gaps for welding the connecting tabs 2, such as... Figure 3 As shown, a first through-welded seam is provided on the shovel-shaped structure 6 on the outer periphery of the current collector, and a second through-welded seam is provided on the boss 8 at the center of the current collector. Both the shovel-shaped structure 6 and the boss 8 on the current collector have welded structures. The first welded seam on the shovel-shaped structure 6 is used to weld the current collector to the positive electrode tab 2 of the sodium-ion battery 1, and the second welded seam on the boss 8 is used to weld the current collector to the positive terminal 4 of the lithium-ion battery 3. The boss 8 in the middle of the current collector is a cylindrical structure, which can fit tightly with the positive terminal 4 of the lithium-ion battery 3. The inside of the boss 8 is a hollow structure, which facilitates the subsequent battery management system to provide structural support for the separate charging and discharging of the lithium-ion battery 3 and the sodium-ion battery 1. The lithium-ion battery 3 can also have a current collector structure inside. Since the existing current collector design is already quite complete, it will not be described in detail in this embodiment. There are two current collector structures at the positive electrode of the battery; in this embodiment, only the current collector of the tubular sodium-ion battery 1 will be described.

[0043] Sodium-ion battery 1 and lithium-ion battery 3 can be spaced apart or connected via circumferential surfaces, eliminating point and line contact. This results in a more stable structure and more uniform heat dissipation under external forces. Due to the more uniform stress distribution, the battery cell is stronger and less prone to explosion in special environments.

[0044] When the inner casing of sodium-ion battery 1 is separated from the outer casing of lithium-ion battery 3, a liquid cooling system 5 is arranged between lithium-ion battery 3 and sodium-ion battery 1. This liquid cooling system 5 can simultaneously contact both sodium-ion battery 1 and lithium-ion battery 3, increasing the heat dissipation area and uniformly transferring heat to lithium-ion battery 3 during the preheating process of sodium-ion battery 1. Sodium-ion battery 1 and lithium-ion battery 3 have independent battery casing structures. If the packaged battery has no internal liquid cooling structure, the inner casing of sodium-ion battery 1 and the outer casing of lithium-ion battery 3 can be integrated, with the connection point of the two batteries sharing the same battery casing, reducing the material used in the casing structure and increasing the energy density.

[0045] Since both sodium-ion battery 1 and lithium-ion battery 3 have a circular structure, they can both be manufactured using battery winding technology, facilitating the fabrication of structures such as current collectors. Both the positive and negative electrode plates need to have pre-reserved portions for the multi-tabs 2. Both sodium-ion battery 1 and lithium-ion battery 3 can have a casing, a positive electrode, a negative electrode, a separator, and an electrolyte. The positive electrode, separator, and negative electrode of lithium-ion battery 3 are sequentially wound or stacked, injected with electrolyte, and packaged to form lithium-ion battery 3. The positive electrode, separator, and negative electrode of sodium-ion battery 1 are sequentially wound or stacked, injected with electrolyte, and packaged to form sodium-ion battery 1. If the packaged battery does not have an internal liquid cooling structure, the winding operation is performed directly on the casing of lithium-ion battery 3, followed by the packaging operation. Before cutting, the positive and negative electrode plates need to have pre-reserved portions for the multi-tabs 2; after winding, the multi-tabs 2 are stacked in sequence.

[0046] The manufacturing method of the positive electrode sheet for sodium-ion battery 1 and lithium-ion battery 3 is as follows: the positive electrode material is mixed with a conductive agent and a binder, coated onto an aluminum foil current collector, dried, and then compacted. The manufacturing method of the negative electrode sheet for sodium-ion battery 1 and lithium-ion battery 3 is as follows: the negative electrode material is mixed with a conductive agent and a binder, coated onto a copper foil current collector, dried, and then compacted. The conductive agent is carbon black, etc.; the binder is polyvinylidene fluoride (PVDF), etc.; the positive electrode material of lithium-ion battery 3 is selected from one or more of lithium cobalt oxide (LiCoO2), lithium manganese oxide (LiMn2O4), lithium nickel oxide (LiNiO2), nickel cobalt manganese (NCM), nickel cobalt aluminum (NCA), lithium iron phosphate (LiFePO4), lithium-rich manganese-based materials, layered lithium nickel oxide, and lithium manganese oxide; the positive electrode material of sodium-ion battery 1 is selected from one or more of metal oxides, polyanionic compounds, Prussian blue compounds, phosphate compounds, and Prussian white compounds; the negative electrode materials of lithium-ion battery 3 and sodium-ion battery 1 are selected from one or more of natural graphite, artificial graphite, mesophase carbon microspheres, soft carbon, hard carbon, graphene, silicon-based materials and their composite materials.

[0047] The multi-tab lithium-sodium composite battery of this invention can adopt the following dimensions: the outer diameter of sodium-ion battery 1 is 18mm-100mm; the outer diameter of lithium-ion battery 3 is 15mm-90mm; and the height of both sodium-ion battery 1 and lithium-ion battery 3 is 40mm-200mm.

[0048] The aforementioned multi-tab lithium-sodium composite battery is composed of a central cylindrical lithium-ion battery 3 and an outer tubular sodium-ion battery 1. It fully utilizes the high safety and excellent low-temperature charge-discharge performance of the sodium-ion battery 1, as well as the high energy density of the lithium-ion battery 3. The use of the lithium-ion battery 3 ensures the high energy density of the battery. At the same time, the positive electrodes of the sodium-ion battery 1 and the lithium-ion battery 3 adopt a multi-tab structure and are welded to the current collector. Compared with the single-tab structure, this battery has lower internal resistance and significantly reduces heat generation during use. The sodium-ion battery 1 and the lithium-ion battery 3 are connected in parallel and can be charged and discharged independently. The sodium-ion battery 1 is used to provide temperature control assistance for the energy storage of the lithium-ion battery 3 and, together with the current collector, can prevent the lithium-ion battery 3 from exploding. The current on the sodium-ion battery 1 can be conducted to the positive terminal 4 of the lithium-ion battery 3 through the current collector, making the internal resistance of the composite battery lower, the integration better, and the stability more under external forces. Due to the multi-tab structure design and the use of current collectors, the above-mentioned multi-tab lithium-sodium composite battery eliminates the positive terminal 4 structure of the sodium-ion battery 1, giving it the advantages of low internal resistance and significantly reduced heat generation.

[0049] Therefore, composite batteries with the above structure have the characteristics of more stable structure under external force conditions, higher cell strength, lower internal resistance, better low temperature adaptability, more uniform heat dissipation, less prone to explosion, and better safety.

[0050] The aforementioned multi-tab lithium-sodium composite battery has the following multiple starting methods:

[0051] 1. Sodium-ion battery 1 starts first, followed by lithium-ion battery 3. In cold weather, sodium-ion battery 1 is discharged first to heat up lithium-ion battery 3 before startup, raising its temperature to its optimal operating temperature. A temperature sensor is installed inside the battery pack; once the optimal temperature is reached, the battery management system starts lithium-ion battery 3.

[0052] 2. Sodium-ion battery 1 and lithium-ion battery 3 can be started simultaneously. Under normal ambient temperature and without special safety requirements, sodium-ion battery 1 and lithium-ion battery 3 can be started simultaneously. Since sodium-ion battery 1 and lithium-ion battery 3 are connected in parallel, the working voltage of the composite battery can be increased, which is also suitable for scenarios requiring high power.

[0053] 3. Lithium-ion battery 3 starts, sodium-ion battery 1 does not. In scenarios requiring short-range use and rapid recharging, lithium-ion battery 3 has a higher charging power, so only lithium-ion battery 3 can be used to start the battery, meeting the need for rapid recharging. In certain flammable and explosive special scenarios, if absolute battery safety is required, only lithium-ion battery 3 can be charged and discharged, and the covering of sodium-ion battery 1 can ensure the relative safety of the lithium battery.

[0054] The aforementioned composite battery is controlled by a battery management system (BMS). In low-temperature charging and discharging scenarios, the sodium-ion battery can be started first, reaching the optimal operating temperature of the lithium-ion battery before starting the lithium-ion battery. This improves battery performance at low temperatures and extends battery life. The sodium-ion and lithium-ion batteries each have independent casing structures, giving the battery strong structural strength. Because lithium-ion batteries have relatively low safety, the encasing sodium-ion battery structure and current collector structure prevent direct impact on nearby lithium-ion batteries in the event of a fire or explosion.

[0055] Obviously, those skilled in the art can make various modifications and variations to the embodiments of the present invention without departing from the spirit and scope of the invention. Therefore, if these modifications and variations fall within the scope of the claims of the present invention and their equivalents, the present invention also intends to include these modifications and variations.

Claims

1. A multi-pole lithium-sodium hybrid battery, characterized by, The sodium ion battery and the lithium ion battery are in parallel structure and can be independently charged and discharged; the lithium ion battery is used for energy storage and maintaining working voltage; the sodium ion battery is used for providing temperature control and assisting the lithium ion battery in energy storage, and can block explosion of the lithium ion battery; The lithium ion battery has a positive terminal and a negative terminal; the sodium ion battery and the positive terminal of the lithium ion battery both adopt a multi-tab structure; the current collector disc is welded with the tabs of the sodium ion battery and the lithium ion battery; The top end of the sodium ion battery is uniformly distributed with a plurality of tabs in the circumferential direction; The outer periphery of the current collector disc is provided with a shovel-shaped structure corresponding to the tabs of the sodium ion battery, and a boss is arranged at the center; The shovel-shaped structure is welded with the corresponding tab; the inner cavity of the boss is larger than the positive terminal of the lithium ion battery, is welded with the tab of the lithium ion battery, and is sleeved on the positive terminal of the lithium ion battery; The shovel-shaped structure and the boss are both provided with a welding gap for welding the tab; The sodium ion battery and the lithium ion battery are in contact through the circumferential surface; The inner periphery side shell of the sodium ion battery and the outer periphery side shell of the lithium ion battery share the same shell.

2. The multi-pole lithium-sodium composite battery of claim 1, wherein, A liquid cooling system is arranged between the lithium ion battery and the sodium ion battery.

3. The multi-pole lithium-sodium composite battery of claim 1, wherein, Both the sodium ion battery and the lithium ion battery are made by a battery roll core process.

4. The multi-pole lithium-sodium composite battery of claim 1, wherein, The manufacturing method of the positive plate of the sodium ion battery and the lithium ion battery is that: the positive material is mixed with a conductive agent and a binder, and then coated on an aluminum foil current collector, dried and compacted; The manufacturing method of the negative plate of the sodium ion battery and the lithium ion battery is that: the negative material is mixed with a conductive agent and a binder, and then coated on a copper foil current collector, dried and compacted.

5. The multi-pole lithium-sodium hybrid battery of claim 4, wherein, The conductive agent is carbon black; the binder is polyvinylidene fluoride PVDF; The positive material of the lithium ion battery is selected from one or more of lithium cobaltate, lithium manganate, lithium nickelate, nickel cobalt manganese, nickel cobalt aluminum, lithium iron phosphate, lithium-rich manganese-based material, layered lithium nickelate and lithium manganate; The positive material of the sodium ion battery is selected from one or more of metal oxides, polyanion compounds, prussian blue compounds, phosphate compounds and prussian white compounds; The negative material of the lithium ion battery and the sodium ion battery is selected from one or more of natural graphite, artificial graphite, mesocarbon microbeads, soft carbon, hard carbon, graphene, silicon-based materials and composite materials thereof.

6. The multi-pole lithium-sodium composite battery of any one of claims 1-5, wherein, The outer diameter of the sodium ion battery is 18mm-100mm; The outer diameter of the lithium ion battery is 15mm-90mm; The height of the sodium ion battery and the lithium ion battery is 40mm-200mm.

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