Cylindrical lithium ion battery

Abstract

The utility model provides a cylindrical lithium ion battery, which relates to the technical field of batteries and comprises a shell, an infiltration path formed by a plurality of liquid guide structures is arranged on the inner wall of the shell, a roll core is placed in the inner space of the shell, and a positive terminal and a negative cover plate are respectively arranged at the upper end and the lower end of the shell. The battery cell has the beneficial effects that the internal space of the battery cell shell is increased by adding a plurality of liquid guide structures, and the liquid injection amount is increased; the infiltrating path of the battery cell is increased, and a new path for infiltrating from the cylindrical side surface to the inner ring of the battery cell is added on the basis of a single path of infiltrating the two ends of the traditional cylindrical battery cell; the backflow of electrolyte in the charge-discharge cycle process of the battery cell is promoted, and the abnormities of battery cell liquid shortage, large internal resistance, lithium precipitation and the like are improved.

Description

Technical Field

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

[0002] In the pursuit of high-energy-density lithium-ion batteries, improving electrode capacity utilization and shortening wetting time to overcome the challenges posed by high electrode compaction density have become urgent technical problems. Optimizing electrolyte wettability is considered a key breakthrough point, as it directly affects the uniform distribution of current density and the stability of the solid electrolyte interphase (SEI) film. Uneven wetting not only exacerbates performance fluctuations but may also induce lithium plating at the negative electrode, threatening battery safety.

[0003] Cylindrical lithium-ion batteries, with their robust steel casing and uniform stress distribution on a cylindrical surface, are gradually becoming a popular choice in the power battery market. However, in the pursuit of fast charging and long driving range for electric vehicles, the introduction of silicon anode materials, while significantly improving energy density, also brings the challenge of approximately 300% volume expansion. The design pursuit of high mass margin, while aiming to maximize energy density, leads to a reduction in the cell's electrolyte filling coefficient. Coupled with the compact internal space, the problem of electrolyte wetting becomes increasingly prominent.

[0004] In particular, the volume expansion effect of the silicon anode causes a surge in the filler mass after the first charge, causing it to adhere tightly to the inner wall of the casing and restricting the free flow of the electrolyte. During charging, the electrolyte is easily squeezed out of the cell. If it cannot be returned in time, it will cause serious problems such as electrolyte shortage, increased internal resistance, and lithium plating, directly damaging battery performance and lifespan.

[0005] Although existing technologies (such as patent CN114865252A) have attempted to promote electrolyte turbulence and accelerate the wetting process through ultrasound, this method not only increases equipment costs but also fails to effectively solve the problem of slow electrolyte reflux wetting in actual charge-discharge cycles.

[0006] Therefore, for cylindrical cells, there is an urgent need to develop a new strategy that can effectively improve the initial wetting performance and ensure rapid electrolyte reflow wetting during actual battery use. This is of vital importance for improving the overall performance and safety of lithium-ion batteries. Utility Model Content

[0007] To address the problems existing in the prior art, this utility model provides a cylindrical lithium-ion battery, comprising:

[0008] The housing has an inner wall with an immersion path formed by multiple liquid guiding structures.

[0009] Preferably, the liquid guiding structure consists of multiple protrusions, and the gaps between adjacent protrusions form the wetting path.

[0010] Preferably, the height of the protrusion is 8% to 25% of the thickness of the shell, and the width of the protrusion is 60 μm to 150 μm.

[0011] Preferably, each of the protrusions is arranged longitudinally along the inner wall of the housing, and the interval between protrusions in adjacent columns is 80μm~160μm.

[0012] Preferably, the protrusion is hemispherical.

[0013] Preferably, the liquid guiding structure comprises multiple liquid guiding channels, each of which forms one immersion path.

[0014] Preferably, the depth of the liquid guiding groove is 5% to 20% of the thickness of the shell, and the width of the liquid guiding groove is 50 μm to 120 μm.

[0015] Preferably, the liquid guiding groove is a semi-cylindrical shape or a tetrahedron with rounded corners.

[0016] Preferably, the liquid guiding grooves are arranged longitudinally along the inner wall of the shell, and the interval between adjacent liquid guiding grooves is 100μm~180μm.

[0017] Preferably, a core is placed inside the housing, and liquid at both ends of the housing passes through the gaps in the core and / or the wetting path.

[0018] The above technical solution has the following advantages or beneficial effects:

[0019] 1) The inner wall of the casing is reinforced with multiple liquid-conducting structures to increase the internal space of the battery cell casing and improve the liquid injection volume;

[0020] 2) The inner wall of the casing increases the wetting path of the cell by adding a wetting path formed by multiple liquid guiding structures. On the basis of the single path of traditional cylindrical cells which is mainly wetting at both ends, a new path of wetting from the cylindrical side to the inner ring of the cell is added.

[0021] 3) The inner wall of the casing can promote the return of electrolyte during the charge and discharge cycle of the battery cell by increasing the wetting path formed by multiple liquid guiding structures, thereby improving abnormalities such as insufficient electrolyte, high internal resistance, and lithium plating in the battery cell. Attached Figure Description

[0022] Figure 1 A cross-sectional view of a cylindrical lithium-ion battery is shown in a preferred embodiment of this utility model.

[0023] Figure 2 This is a schematic diagram of the immersion path in a preferred embodiment of the present invention.

[0024] Figure 3 This is a schematic diagram of the structure of the protrusion in a preferred embodiment of the present invention;

[0025] Figure 4 This is a schematic diagram of the liquid guiding groove in a preferred embodiment of the present invention. Detailed Implementation

[0026] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The present invention is not limited to this embodiment; other embodiments that conform to the spirit of the present invention may also fall within its scope.

[0027] In a preferred embodiment of this utility model, based on the above-mentioned problems existing in the prior art, a cylindrical lithium-ion battery is provided, comprising:

[0028] The housing 1 has an inner wall with an immersion path formed by multiple liquid guiding structures 100. A core 2 is placed inside the housing 1. Liquid from both ends of the housing 1 passes through the gaps in the core 2 and / or the immersion path.

[0029] Specifically, in this embodiment, the internal space of the lithium-ion battery casing 1 houses the core 2, and the upper and lower ends of the casing 2 are respectively provided with a positive terminal 3 and a negative terminal cover 4. Furthermore, multiple liquid-conducting structures 100 are added to the inner wall of the casing 1. The advantages are:

[0030] On the one hand, due to the high group margin of cylindrical lithium-ion batteries and the large proportion of the core in the casing space, the electrolyte injection volume is lower compared to square and soft-pack cells, and the electrolyte wetting is more difficult. The advantage of the liquid guiding structure added to the inner wall of the casing in this embodiment is that it can increase the space between the inner wall of the casing 1 and the core 2, accommodate more electrolyte and increase the liquid retention.

[0031] On the other hand, after adapting to the high energy density scheme of high nickel + silicon-based negative electrode, the cylindrical lithium-ion battery expands after the first charge. The outermost layer of the core 1 is tightly attached to the inner wall of the shell 1, and the electrolyte is squeezed out of the core 2 and flows into the gap 200 between the core 2, the positive terminal 3 and the negative electrode cover plate 4. When the electrolyte flows back, it can only flow into the core from the central hole 300 in the center of the core 2. The return path is single, which leads to the cell being short of liquid during the cycle, the internal resistance increases, and the risk of lithium plating is relatively high. However, in this embodiment, each liquid guiding structure 100 forms an additional wetting path on the inner wall of the shell 1. Compared with traditional batteries, this increases the number of electrolyte return paths, improves the wetting rate of the core, and avoids abnormalities such as the core being short of liquid, high internal resistance, lithium plating, and cell failure at the end of the cycle.

[0032] Specifically, the wetting path of the electrolyte flow is as follows: Figure 2As shown, compared to the traditional path A of return through the central hole, the cylindrical lithium-ion battery of this invention adds a wetting path B on the inner wall of the casing, increasing the number of wetting paths and improving wetting efficiency.

[0033] Furthermore, the casing of the cylindrical lithium-ion battery in this embodiment can be made by integral die casting or by secondary processing (such as pulsed laser texturing, chemical etching, ultrasonic texturing, or a combination of one or more processes). Compared with other existing technologies for solving problems such as poor liquid retention and cell cycle failure, the above effects can be achieved without adding additional components inside the battery.

[0034] In a preferred embodiment of this invention, the liquid guiding structure 100 consists of a plurality of protrusions 110, and the gaps between adjacent protrusions 110 form an immersion path; the height of the protrusions 110 is 8% to 25% of the thickness of the shell 1, and the width of the protrusions 110 is 60 to 150 μm; each protrusion 110 is arranged longitudinally along the inner wall of the shell 1, and the interval between adjacent columns of protrusions 110 is 80 μm to 160 μm; the protrusions 110 are hemispherical or have rounded corners.

[0035] Specifically, in one preferred embodiment of this utility model, the liquid guiding structure 100 is a protrusion 110, such as... Figure 3 As shown, multiple protrusions 110 are arranged longitudinally on the inner wall of the housing 1. There is a gap between every two adjacent protrusions 110 to store a certain amount of electrolyte. Multiple rows are arranged around the inner wall of the housing 1 in this manner, and the gaps between adjacent rows are interconnected to form a wetting path for the electrolyte to flow through. During the battery charge and discharge cycle, the electrolyte can flow back to the core 1 from the wetting path on the inner wall of the housing, increasing the number of wetting paths and improving the wetting efficiency.

[0036] The shape of the protrusion 110 can be various. In this embodiment, a hemispherical shape is preferred because it has better structural strength. In other embodiments, other structures can also be used, such as frustum, tetrahedron, etc. However, it should be noted that no matter what shape is used, the sharp parts need to be chamfered in order to avoid the protrusion being too sharp and damaging the core.

[0037] In a preferred embodiment of the present invention, the liquid guiding structure includes multiple liquid guiding grooves 120, each of which forms an immersion path. The depth of the liquid guiding groove 120 is 5% to 20% of the thickness of the shell 1, the width of the liquid guiding groove 120 is 50 to 120 μm, the liquid guiding groove 120 is semi-cylindrical, the liquid guiding grooves 120 are arranged longitudinally along the inner wall of the shell, and the interval between adjacent liquid guiding grooves 120 is 100 μm to 180 μm.

[0038] Specifically, in this embodiment, the liquid guiding structure 100 can also be a liquid guiding groove 120; each liquid guiding groove 120 is arranged longitudinally from top to bottom, and multiple liquid guiding grooves 120 are arranged on the inner wall of the shell 1. The depth of the liquid guiding groove 120 is preferably 5% to 20% of the thickness of the shell 1 to avoid the inner wall of the shell 1 becoming too thin due to excessive groove depth, thereby reducing the strength of the shell 1 structure. In this embodiment, the liquid guiding groove 120 is preferably semi-cylindrical in shape, which has better structural strength. It can also be made of, etc. Figure 4 The rectangular shape shown can be replaced with other shapes in other embodiments as long as they can achieve the effect of having a certain amount of space. In this embodiment, the electrolyte in the liquid guiding groove 120 can flow vertically. During the battery charging and discharging cycle, the electrolyte can flow back to the core from the wetting path on the inner wall of the shell 1, which increases the number of wetting paths and improves the wetting efficiency.

[0039] The above are merely preferred embodiments of the present utility model and are not intended to limit the implementation methods and protection scope of the present utility model. Those skilled in the art should realize that any equivalent substitutions and obvious changes made using the content of this specification and illustrations should be included within the protection scope of the present utility model.

Claims

1. A cylindrical lithium-ion battery, characterized in that, include: The housing has an inner wall with an immersion path formed by multiple liquid guiding structures; The liquid guiding structure consists of protrusions, and the gaps between adjacent protrusions form the wetting path.

2. The cylindrical lithium-ion battery according to claim 1, characterized in that, The height of the protrusion is 8% to 25% of the thickness of the shell, and the width of the protrusion is 60 μm to 150 μm.

3. The cylindrical lithium-ion battery according to claim 1, characterized in that, The protrusions are arranged longitudinally along the inner wall of the housing, and the interval between the protrusions in adjacent columns is 80μm~160μm.

4. The cylindrical lithium-ion battery according to claim 1, characterized in that, The protrusion is hemispherical or a tetrahedron with rounded corners.

5. The cylindrical lithium-ion battery according to claim 1, characterized in that, The housing contains a core, and liquid at both ends of the housing passes through the gaps in the core and / or the wetting path.

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