Lithium battery with optimized distribution of flow guides

Abstract

The utility model discloses a lithium battery with optimal distribution structure of flow guide body, this lithium battery includes casing, electric core body, positive pole lug, negative pole lug and electrolyte, and electric core body sets up in casing, and electrolyte fills in the inside of casing, electric core body is by multiple positive pole piece, multiple negative pole piece and multiple diaphragm alternately superimposed and is formed, and all is provided with flow guide body structure on positive pole piece and negative pole piece, flow guide body structure includes main flow guide layer and branch flow guide network, and main flow guide layer is connected with positive pole lug, negative pole lug respectively, and branch flow guide network is distributed in the both sides of main flow guide layer in radial shape, and the density of branch flow guide network gradually increases from main flow guide layer to the edge of positive pole piece, negative pole piece, through optimizing the distribution structure of flow guide body, the utility model can effectively promote the uniformity of current conduction, reduce the ohm resistance in the battery, reduce local overheat phenomenon, prolong the cycle life of battery, be applicable to high rate discharge scene.

Description

Technical Field

[0001] This utility model relates to the field of lithium battery technology, specifically to a lithium battery with an optimized distribution structure of fluid conductors. Background Technology

[0002] Lithium-ion batteries are widely used in portable electronic devices, electric vehicles, and energy storage systems due to their advantages such as high energy density, long cycle life, and no memory effect. However, as the performance requirements for lithium-ion batteries in these applications continue to increase, especially in high-rate discharge scenarios, current conduction efficiency, heat dissipation performance, and cycle stability have become key factors restricting their development. As a crucial component for current conduction within lithium batteries, the distribution structure of the fluid conductor directly impacts the uniformity and efficiency of the internal current. Current lithium battery fluid conductors typically employ a single metal foil or a simple mesh structure, resulting in a relatively uniform distribution on both the positive and negative electrodes. However, this distribution method has significant drawbacks: during charging and discharging, current primarily flows from the area near the tabs to the electrode edges. Because the electrode edges are farther from the tabs, the current conduction path is longer, leading to lower current density at the edges and higher current density near the tabs, which can easily cause localized overheating. Furthermore, a uniformly distributed fluid conductor cannot adaptively adjust to the demands of the current conduction path, resulting in higher ohmic impedance and lower current conduction efficiency within the battery, thus affecting the battery's rate performance and cycle life. Furthermore, existing lithium-ion batteries typically use a single material for their conductive fluids, such as aluminum foil for the positive electrode and copper foil for the negative electrode. While these materials offer good conductivity, they are prone to corrosion and oxidation during long-term charge-discharge cycles, leading to a decrease in the conductivity of the conductive fluid and further shortening the battery's lifespan. Therefore, there is an urgent need to design a lithium-ion battery with an optimized conductive fluid distribution structure to address these issues. Utility Model Content

[0003] The purpose of this invention is to provide a lithium battery with an optimized distribution structure of the fluid conductor, so as to solve the problems of low current conduction efficiency, local overheating and short cycle life caused by unreasonable distribution of the fluid conductor in existing lithium batteries.

[0004] To solve the above technical problems, the present invention achieves this through the following solution: The present invention provides a lithium battery with an optimized distribution structure for fluid conductivity, comprising a casing, a cell assembly, a positive electrode tab, a negative electrode tab, and an electrolyte. The cell assembly is disposed within the casing, and the electrolyte fills the interior of the casing. The cell assembly includes a front frame and a rear frame, and the four corners of the front frame and the rear frame are connected by connectors to form a protective frame. The cell body is disposed within the protective frame. One end of the positive electrode tab and one end of the negative electrode tab extend to the outside of the housing, and the other ends are electrically connected to the battery cell body; the battery cell body is composed of multiple positive electrode plates, multiple separators, and multiple negative electrode plates stacked alternately, and the separators are disposed between adjacent positive electrode plates and negative electrode plates; The positive electrode sheet includes a positive electrode substrate, a positive electrode active material layer, and a positive electrode fluid-conducting structure. The positive electrode active material layer is coated on both sides of the positive electrode substrate, and the positive electrode fluid-conducting structure is embedded inside the positive electrode active material layer and connected to the positive electrode tab. The negative electrode sheet includes a negative electrode substrate, a negative electrode active material layer, and a negative electrode fluid guiding structure. The negative electrode active material layer is coated on both sides of the negative electrode substrate, and the negative electrode fluid guiding structure is embedded inside the negative electrode active material layer and connected to the negative electrode tab. Both the positive electrode fluid guiding structure and the negative electrode fluid guiding structure include a main flow layer and a branch flow guiding network. The main flow layer is arranged along the length direction of the positive electrode and the negative electrode, and the branch flow guiding network is radially distributed on both sides of the main flow layer. The branched flow guiding network includes a primary flow guiding wire, a secondary flow guiding wire, and a tertiary flow guiding wire. One end of the primary flow guiding wire is perpendicularly connected to the main flow layer. One end of the secondary flow guiding wire is connected to the end of the primary flow guiding wire away from the main flow layer, and the angle between the secondary flow guiding wire and the primary flow guiding wire is 120° to 125°. One end of the tertiary flow guiding wire is connected to the end of the secondary flow guiding wire away from the primary flow guiding wire, and the angle between the tertiary flow guiding wire and the secondary flow guiding wire is 120° to 125°.

[0005] Furthermore, the thickness of the main flow layer is 8-12 μm, the diameter of the first-stage flow guide wire is 5-8 μm, the diameter of the second-stage flow guide wire is 3-5 μm, and the diameter of the third-stage flow guide wire is 1-3 μm.

[0006] Furthermore, both the positive electrode substrate and the negative electrode substrate are metal foils. The positive electrode substrate is made of aluminum foil with a thickness of 12-15 μm, and the negative electrode substrate is made of copper foil with a thickness of 8-10 μm.

[0007] Furthermore, the diaphragm is a polypropylene-polyethylene-polypropylene three-layer composite diaphragm with a thickness of 16-20 μm, and the diaphragm is provided with a plurality of micropores with a pore size of 0.1-0.3 μm and a porosity of 40%-50%. Furthermore, the housing includes an outer shell and a cover plate. The cover plate is sealed to the outer shell by laser welding. A positive electrode post and a negative electrode post are provided on the cover plate. The end of the positive electrode post away from the cell body is welded to the positive electrode post, and the end of the negative electrode post away from the cell body is welded to the negative electrode post. Furthermore, the cover plate is also provided with an explosion-proof valve, which includes an explosion-proof membrane and a protective cover. The explosion-proof membrane is disposed in a pressure relief hole opened on the cover plate, and the protective cover is fixed to the cover plate by a threaded connection, and the protective cover covers the outside of the explosion-proof membrane. Furthermore, a temperature sensor and a pressure sensor are also provided inside the housing, and the temperature sensor and the pressure sensor are electrically connected to the external battery management system via wires. Furthermore, the positive electrode fluid-conducting structure and the negative electrode fluid-conducting structure are made of either a copper-nickel alloy or an aluminum-nickel alloy.

[0008] Compared with the prior art, the beneficial effects of this utility model are: 1. This utility model improves the uniformity of current conduction: the fluid guide adopts a "main flow layer + radial branch flow guide network" structure. The branch flow guide network extends to the edge of the electrode, shortens the current conduction path in the edge area, reduces the current density near the electrode tab, and avoids local overheating.

[0009] 2. This utility model reduces ohmic impedance: The gradient size design of the branch current-conducting network is adapted to the current conduction law, reducing current conduction resistance, lowering the internal ohmic impedance of the battery, and improving current conduction efficiency and rate performance.

[0010] 3. This utility model extends cycle life: the fluid conductor is made of copper-nickel alloy or aluminum-nickel alloy, which has stronger corrosion resistance and oxidation resistance, reducing the impact of material degradation on conductivity; at the same time, the optimized current distribution reduces electrode polarization and extends battery cycle life.

[0011] 4. This utility model enhances structural stability: The cell assembly forms a protective frame through the front frame, rear frame and connectors, which effectively protects the cell body and improves the overall structural stability and impact resistance of the battery. Attached Figure Description

[0012] Figure 1 This is a structural diagram of the battery cell assembly of this utility model.

[0013] Figure 2 This is a structural diagram of the battery cell body of this utility model.

[0014] Figure 3 This is a diagram of the positive electrode fluid-conducting structure or the negative electrode fluid-conducting structure of this utility model.

[0015] In the attached diagram, the following labels are used: 2-cell assembly, 3-positive electrode tab, 4-negative electrode tab, 6-main current layer, 7-branch current guiding network, 21-positive electrode sheet, 22-negative electrode sheet, 23-diaphragm, 71-primary current guiding wire, 72-secondary current guiding wire, 73-tertiary current guiding wire, 123-explosion-proof valve, 201-front frame, 202-rear frame, 203-cell body, 204-connector, 211-positive electrode substrate, 212-positive electrode active material layer, 213-positive electrode current guiding structure, 221-negative electrode substrate, 222-negative electrode active material layer, 223-negative electrode current guiding structure. Detailed Implementation

[0016] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments, so that the advantages and features of the present utility model can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present utility model. Obviously, the embodiments described in this utility model are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0017] Furthermore, the technical features involved in the different embodiments of this utility model described below can be combined with each other as long as they do not conflict with each other.

[0018] Example 1: The specific structure of this utility model is as follows: Please refer to the appendix. Figure 1-3 The present invention discloses a lithium battery with an optimized distribution structure for fluid conductivity, comprising a casing, a cell assembly 2, a positive electrode tab 3, a negative electrode tab 4, and an electrolyte. The cell assembly 2 is disposed within the casing, and the electrolyte fills the interior of the casing. The cell assembly 2 includes a front frame 201 and a rear frame 202. The four corners of the front frame 201 and the rear frame 202 are connected by connectors 204 to form a protective frame, and the cell body 203 is disposed within the protective frame. One end of the positive electrode tab 3 and one end of the negative electrode tab 4 extend to the outside of the housing, and the other ends are electrically connected to the cell body 203 respectively; the cell body 203 is formed by alternatingly stacking multiple positive electrode plates 21, multiple separators 23, and multiple negative electrode plates 22, and the separators 23 are disposed between adjacent positive electrode plates 21 and negative electrode plates 22; The positive electrode 21 includes a positive electrode substrate 211, a positive electrode active material layer 212, and a positive electrode fluid guiding structure 213. The positive electrode active material layer 212 is coated on both sides of the positive electrode substrate 211, and the positive electrode fluid guiding structure 213 is embedded inside the positive electrode active material layer 212. The positive electrode fluid guiding structure 213 is connected to the positive electrode tab 3. The negative electrode sheet 22 includes a negative electrode substrate 221, a negative electrode active material layer 222, and a negative electrode fluid guiding structure 223. The negative electrode active material layer 222 is coated on both sides of the negative electrode substrate 221, and the negative electrode fluid guiding structure 223 is embedded inside the negative electrode active material layer 222. The negative electrode fluid guiding structure 223 is connected to the negative electrode tab 4. Both the positive electrode fluid guiding structure 213 and the negative electrode fluid guiding structure 223 include a main flow layer 6 and a branch flow guiding network 7. The main flow layer 6 is arranged along the length direction of the positive electrode 21 and the negative electrode 22, and the branch flow guiding network 7 is radially distributed on both sides of the main flow layer 6. The branched flow guiding network 7 includes a primary flow guiding wire 71, a secondary flow guiding wire 72, and a tertiary flow guiding wire 73. One end of the primary flow guiding wire 71 is perpendicularly connected to the main flow layer 6. One end of the secondary flow guiding wire 72 is connected to the end of the primary flow guiding wire 71 away from the main flow layer 6, and the angle between the secondary flow guiding wire 72 and the primary flow guiding wire 71 is 120° to 125°. One end of the tertiary flow guiding wire 73 is connected to the end of the secondary flow guiding wire 72 away from the primary flow guiding wire 71, and the angle between the tertiary flow guiding wire 73 and the secondary flow guiding wire 72 is 120° to 125°.

[0019] In a preferred embodiment, the thickness of the main flow layer 6 is 8-12 μm, the diameter of the primary flow guide wire 71 is 5-8 μm, the diameter of the secondary flow guide wire 72 is 3-5 μm, and the diameter of the tertiary flow guide wire 73 is 1-3 μm.

[0020] In a preferred embodiment, both the positive electrode substrate 211 and the negative electrode substrate 221 are metal foils. The positive electrode substrate 211 is made of aluminum foil with a thickness of 12-15 μm, and the negative electrode substrate 221 is made of copper foil with a thickness of 8-10 μm. In a preferred embodiment, the diaphragm 23 is a polypropylene-polyethylene-polypropylene three-layer composite diaphragm with a thickness of 16-20 μm, and the diaphragm 23 is provided with a plurality of micropores with a pore size of 0.1-0.3 μm and a porosity of 40%-50%. A preferred embodiment of the present invention is as follows: the housing includes an outer shell and a cover plate. The cover plate is sealed to the outer shell by laser welding. A positive electrode post and a negative electrode post are provided on the cover plate. The end of the positive electrode tab 3 away from the cell body 203 is welded to the positive electrode post, and the end of the negative electrode tab 4 away from the cell body 203 is welded to the negative electrode post. In a preferred embodiment, the cover plate is further provided with an explosion-proof valve 123. The explosion-proof valve 123 includes an explosion-proof membrane and a protective cover. The explosion-proof membrane is disposed in a pressure relief hole opened on the cover plate 12. The protective cover is fixed on the cover plate 12 by a threaded connection, and the protective cover covers the outside of the explosion-proof membrane 1231. A preferred embodiment of this technical solution: a temperature sensor and a pressure sensor are also provided inside the housing, and the temperature sensor and the pressure sensor are electrically connected to the external battery management system through wires. In a preferred embodiment, the positive electrode fluid-conducting structure 213 and the negative electrode fluid-conducting structure 223 are made of either a copper-nickel alloy or an aluminum-nickel alloy.

[0021] In a preferred embodiment, the positive electrode active material layer 212 is made by mixing positive electrode active material, conductive agent, and binder in a mass ratio of 90:5:5, wherein the positive electrode active material is a ternary material LiNi0.8Co0.1Mn0.1O2; the negative electrode active material layer 222 is made by mixing negative electrode active material, conductive agent, and binder in a mass ratio of 95:3:2, wherein the negative electrode active material is a composite material of graphite and silicon-based material, wherein the mass ratio of graphite to silicon-based material is 85:15. A preferred embodiment of this technical solution: the electrolyte is composed of lithium salt, organic solvent and additives, wherein the lithium salt is LiPF6 with a concentration of 1.0-1.2 mol / L; the organic solvent is a mixture of ethylene carbonate (EC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC) in a volume ratio of 3:4:3; the additives are fluoroethylene carbonate (FEC) and ethylene sulfite (ES), and the mass fraction of the additives in the electrolyte is 2%-5%.

[0022] Example 2: This embodiment provides a lithium battery with an optimized fluid distribution structure, the specific structure of which is as follows: Battery cell assembly: The front frame 201 and the rear frame 202 are made of ABS material and are connected by plastic bolt connectors 204 to form a protective frame. The battery cell body 203 is placed inside the protective frame.

[0023] The electrode structure is as follows: Positive electrode 21: The positive electrode substrate 211 is a 12μm aluminum foil. The positive electrode active material layer 212 is made of LiNi0.8Co0.1Mn0.1O2, conductive agent and binder mixed in a mass ratio of 90:5:5 and coated on both sides of the substrate. The positive electrode fluid guiding structure 213 is an aluminum-nickel alloy. The main fluid guiding layer 6 is 8μm thick, the primary fluid guiding wire 71 is 5μm in diameter, the secondary fluid guiding wire 72 is 3μm in diameter, and the tertiary fluid guiding wire 73 is 1μm in diameter. It is embedded in the active material layer and welded to the positive electrode tab 3.

[0024] Negative electrode 22: The negative electrode substrate 221 is an 8μm copper foil. The negative electrode active material layer 222 is made of graphite-silicon based composite material in a mass ratio of 85:15, conductive agent and binder in a mass ratio of 95:3:2, and coated on both sides of the substrate. The negative electrode conductive structure 223 is a copper-nickel alloy with the same size as the positive electrode conductive structure. It is embedded in the active material layer and welded to the negative electrode tab 4.

[0025] The membrane is a 16μm polypropylene-polyethylene-polypropylene three-layer composite membrane with a micropore size of 0.1μm and a porosity of 40%.

[0026] Housing and cover: The outer shell is made of aluminum, and the cover is sealed by laser welding; the cover is provided with a positive terminal and a negative terminal, and the electrode lugs are welded to the terminals; in the explosion-proof valve 123 on the cover, the explosion-proof membrane is made of aluminum foil, and the protective cover is made of stainless steel and is fixed by threads.

[0027] Electrolyte: composed of 1.0 mol / L LiPF6, EC:DMC:EMC in a volume ratio of 3:4:3, and 2% FEC+ES additive by mass.

[0028] Sensors: Temperature and pressure sensors are installed inside the housing and connected to the external battery management system via wires.

[0029] Example 3: The difference between this embodiment and Embodiment 1 is that: The positive electrode guide structure 213 has a main flow layer 6 with a thickness of 10μm, a primary guide wire 71 with a diameter of 6μm, a secondary guide wire 72 with a diameter of 4μm, and a tertiary guide wire 73 with a diameter of 2μm.

[0030] The thickness of the positive electrode substrate 211 is 13 μm, and the thickness of the negative electrode substrate 221 is 9 μm.

[0031] The membrane 23 has a thickness of 18 μm, a micropore diameter of 0.2 μm, and a porosity of 45%.

[0032] The electrolyte contains 1.1 mol / L LiPF6 and 3.5% additive by mass.

[0033] Example 4: The difference between this embodiment and Embodiment 1 is that: The positive electrode guide structure 213 has a main flow layer 6 with a thickness of 12μm, a primary guide wire 71 with a diameter of 8μm, a secondary guide wire 72 with a diameter of 5μm, and a tertiary guide wire 73 with a diameter of 3μm.

[0034] The thickness of the positive electrode substrate 211 is 15 μm, and the thickness of the negative electrode substrate 221 is 10 μm.

[0035] The membrane 23 has a thickness of 20 μm, a micropore diameter of 0.3 μm, and a porosity of 50%.

[0036] The electrolyte contains 1.2 mol / L LiPF6 and 5% additive by mass.

[0037] In summary, this invention improves the uniformity of current conduction: the fluid guide adopts a "main flow layer + radial branch flow network" structure, the branch flow network extends to the edge of the electrode, shortens the current conduction path in the edge area, reduces the current density near the electrode tab, and avoids local overheating.

[0038] This invention reduces ohmic impedance by using a gradient size design of the branch current-conducting network to adapt to the current conduction law, thereby reducing current conduction resistance, lowering the internal ohmic impedance of the battery, and improving current conduction efficiency and rate performance.

[0039] This invention extends cycle life: the fluid conductor is made of copper-nickel alloy or aluminum-nickel alloy, which has stronger corrosion resistance and oxidation resistance, reducing the impact of material degradation on conductivity; at the same time, the optimized current distribution reduces electrode polarization and extends battery cycle life.

[0040] This utility model enhances structural stability: the cell assembly forms a protective frame through the front frame, rear frame and connectors, which effectively protects the cell body and improves the overall structural stability and impact resistance of the battery.

[0041] The above description is only a preferred embodiment of the present utility model and does not limit the patent scope of the present utility model. Any equivalent structural or procedural transformations made based on the contents of the present utility model specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present utility model.

Claims

1. A lithium battery with an optimized fluid distribution structure, comprising a casing, a cell assembly (2), a positive electrode tab (3), a negative electrode tab (4), and an electrolyte, characterized in that, The battery cell assembly (2) is disposed inside the housing, and the electrolyte is filled inside the housing. The battery cell assembly (2) includes a front frame (201) and a rear frame (202). The four corners of the front frame (201) and the rear frame (202) are connected by connectors (204) to form a protective frame. The battery cell body (203) is disposed inside the protective frame. One end of the positive electrode tab (3) and one end of the negative electrode tab (4) extend to the outside of the housing, and the other ends are electrically connected to the cell body (203); the cell body (203) is formed by alternating stacking of multiple positive electrode plates (21), multiple separators (23), and multiple negative electrode plates (22), and the separators (23) are disposed between adjacent positive electrode plates (21) and negative electrode plates (22); The positive electrode sheet (21) includes a positive electrode substrate (211), a positive electrode active material layer (212), and a positive electrode fluid-conducting structure (213). The positive electrode active material layer (212) is coated on both sides of the positive electrode substrate (211), and the positive electrode fluid-conducting structure (213) is embedded inside the positive electrode active material layer (212). The positive electrode fluid-conducting structure (213) is connected to the positive electrode tab (3). The negative electrode sheet (22) includes a negative electrode substrate (221), a negative electrode active material layer (222), and a negative electrode fluid guiding structure (223). The negative electrode active material layer (222) is coated on both sides of the negative electrode substrate (221), and the negative electrode fluid guiding structure (223) is embedded inside the negative electrode active material layer (222). The negative electrode fluid guiding structure (223) is connected to the negative electrode tab (4). Both the positive electrode fluid guiding structure (213) and the negative electrode fluid guiding structure (223) include a main flow layer (6) and a branch flow guiding network (7). The main flow layer (6) is arranged along the length direction of the positive electrode (21) and the negative electrode (22), and the branch flow guiding network (7) is radially distributed on both sides of the main flow layer (6). The branch flow guiding network (7) includes a primary flow guiding wire (71), a secondary flow guiding wire (72), and a tertiary flow guiding wire (73). One end of the primary flow guiding wire (71) is perpendicularly connected to the main flow layer (6). One end of the secondary flow guiding wire (72) is connected to the end of the primary flow guiding wire (71) away from the main flow layer (6), and the angle between the secondary flow guiding wire (72) and the primary flow guiding wire (71) is 120° to 125°. One end of the tertiary flow guiding wire (73) is connected to the end of the secondary flow guiding wire (72) away from the primary flow guiding wire (71), and the angle between the tertiary flow guiding wire (73) and the secondary flow guiding wire (72) is 120° to 125°.

2. A lithium battery with an optimized fluid distribution structure according to claim 1, characterized in that, The thickness of the main flow layer (6) is 8-12 μm, the diameter of the primary flow guide wire (71) is 5-8 μm, the diameter of the secondary flow guide wire (72) is 3-5 μm, and the diameter of the tertiary flow guide wire (73) is 1-3 μm.

3. A lithium battery with an optimized fluid distribution structure according to claim 1, characterized in that, Both the positive electrode substrate (211) and the negative electrode substrate (221) are metal foils. The positive electrode substrate (211) is made of aluminum foil with a thickness of 12-15 μm, and the negative electrode substrate (221) is made of copper foil with a thickness of 8-10 μm.

4. A lithium battery with an optimized fluid distribution structure according to claim 1, characterized in that, The diaphragm (23) is a polypropylene-polyethylene-polypropylene three-layer composite diaphragm with a thickness of 16-20μm, and the diaphragm (23) is provided with a plurality of micropores with a pore size of 0.1-0.3μm and a porosity of 40%-50%.

5. A lithium battery with an optimized fluid distribution structure according to claim 1, characterized in that, The housing includes an outer shell and a cover plate. The cover plate is sealed to the outer shell by laser welding. A positive electrode post and a negative electrode post are provided on the cover plate. The end of the positive electrode tab (3) away from the cell body (203) is welded to the positive electrode post. The end of the negative electrode tab (4) away from the cell body (203) is welded to the negative electrode post.

6. A lithium battery with an optimized fluid distribution structure according to claim 5, characterized in that, The cover plate is also provided with an explosion-proof valve (123). The explosion-proof valve (123) includes an explosion-proof membrane and a protective cover. The explosion-proof membrane is disposed in a pressure relief hole opened on the cover plate (12). The protective cover is fixed on the cover plate (12) by means of threaded connection, and the protective cover is disposed on the outside of the explosion-proof membrane (1231).

7. A lithium battery with an optimized fluid distribution structure according to claim 1, characterized in that, The housing also contains a temperature sensor and a pressure sensor, which are electrically connected to an external battery management system via wires.

8. A lithium battery with an optimized fluid distribution structure according to claim 1, characterized in that, The positive electrode fluid guiding structure (213) and the negative electrode fluid guiding structure (223) are made of either copper-nickel alloy or aluminum-nickel alloy.

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