Lithium ion battery and preparation method thereof, battery module

Abstract

The application discloses a lithium ion battery, a preparation method of the lithium ion battery and a battery module, wherein the lithium ion battery comprises a shell, a liquid guide and a battery cell, the shell has a containing cavity, the liquid guide and the battery cell are arranged in the containing cavity, and the liquid guide is located between the shell and the battery cell; the liquid guide is used for conducting electrolyte, so that the electrolyte is circulated and flows in the containing cavity. By arranging the liquid guide between the shell and the battery cell, the liquid guide is used for conducting the electrolyte, the electrolyte is guided from the bottom of the battery to the top, the electrolyte in the battery cell is kept, the situation that after the electrolyte is consumed due to multiple cycles of the battery, the electrolyte cannot be normally transmitted due to gravity, and the upper part of the battery cell lacks the electrolyte and lithium is separated is avoided, the cycle performance of the battery is effectively improved, and the service life of the battery is prolonged.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, specifically to a lithium-ion battery and its preparation method, as well as a battery module. Background Technology

[0002] To improve space utilization and the resistance of battery modules to mechanical impact, hexagonal prism-shaped lithium-ion batteries have been developed.

[0003] Existing hexagonal prism-shaped lithium-ion batteries consist of a hexagonal prism-shaped shell, a columnar cell, and an electrolyte. Although the hexagonal prism-shaped structure improves the utilization of external space, due to manufacturing difficulties and other limitations, the space between the columnar cell and the hexagonal prism-shaped shell is relatively large. At the same time, for safety reasons, the electrolyte inside the battery cannot completely fill the internal space of the hexagonal prism-shaped shell, resulting in a lack of electrolyte in some parts of the battery. After multiple cycles, the electrolyte will be depleted, and the electrolyte may not be able to be transported normally due to gravity, leading to a lack of electrolyte in the upper cell of the battery and the phenomenon of lithium plating. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a lithium-ion battery, its preparation method, and a battery module.

[0005] The present invention discloses a lithium-ion battery comprising a casing, a liquid guiding component, and a battery cell. The casing has a receiving cavity, and the liquid guiding component and the battery cell are respectively disposed in the receiving cavity. The liquid guiding component is located between the casing and the battery cell. The liquid guiding component is used to conduct electrolyte, thereby driving the electrolyte to circulate within the receiving cavity.

[0006] According to one embodiment of the present invention, one side of the liquid guiding component is in close contact with the inner wall of the outer casing, and the other side is in close contact with the side of the battery cell.

[0007] According to one embodiment of the present invention, the liquid guiding element includes at least one of a capillary tube, a fiber tube, and a diaphragm.

[0008] According to one embodiment of the present invention, the liquid guiding component includes a plurality of diaphragms and a plurality of capillaries that are mixed together, and the total volume ratio of the plurality of diaphragms and the plurality of capillaries is 1:(0.5-2).

[0009] According to one embodiment of the present invention, the liquid guiding component includes a plurality of diaphragms and a plurality of fiber tubes mixed together, and the total volume ratio of the plurality of diaphragms and the plurality of fiber tubes is 1:(0.5-2).

[0010] According to one embodiment of the present invention, the battery cell is a wound battery cell, and the height of the liquid guiding component is not lower than the height of the battery cell, perpendicular to the winding direction of the battery cell.

[0011] According to one embodiment of the present invention, the battery cell is a lithium iron phosphate battery cell, a lithium manganese oxide battery cell, a lithium cobalt oxide battery cell, or a ternary nickel cobalt manganese oxide battery cell.

[0012] A method for preparing the above-mentioned lithium-ion battery includes the following steps:

[0013] The liquid guiding component is placed in the receiving cavity of the outer casing;

[0014] The battery cell is placed in the housing cavity of the casing, and the liquid guiding component is located between the battery cell and the casing to obtain a pre-fabricated liquid-conducting battery;

[0015] Prefabricated batteries undergo liquid injection, sealing, formation, settling, and capacity testing to obtain lithium-ion batteries.

[0016] According to one embodiment of the present invention, before the liquid guiding component is placed on the inner wall of the housing, the method further includes the following steps:

[0017] At least one pre-designed liquid guiding component is used, which is a capillary tube, a fiber tube, or a diaphragm.

[0018] A battery module comprising the aforementioned lithium-ion battery.

[0019] The beneficial effects of this application are as follows: by setting a liquid guiding component between the outer casing and the cell, the liquid guiding component is used to conduct the electrolyte, leading the electrolyte from the bottom to the top of the battery, thereby keeping the electrolyte inside the cell. This avoids the situation where the electrolyte is lost after multiple battery cycles, and the electrolyte cannot be transported normally due to gravity, resulting in a lack of electrolyte in the upper part of the cell and lithium deposition. This effectively improves the battery cycle performance and extends the battery life. Attached Figure Description

[0020] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0021] Figure 1 This is a schematic diagram of the lithium-ion battery structure in the embodiment;

[0022] Figure 2 This is a schematic diagram of the battery module structure in the embodiment;

[0023] Figure 3 This is a test diagram of the cycle performance of a battery using polyamide as the liquid guiding component;

[0024] Figure 4 The graph shows the cycle performance test results of a battery with a PP separator as the liquid guiding component.

[0025] Figure 5 This is a test diagram of the cycle performance of a battery using a fiber tube as a liquid guiding component.

[0026] Figure 6 This is a test diagram of the cycle performance of a battery using a capillary tube as the liquid guiding element.

[0027] Figure 7 This is a test diagram of the cycle performance of a battery with a PP separator and fiber tube as the liquid guiding component.

[0028] Figure 8 This is a test chart of the cycle performance of a battery with a PP separator and capillary tube as the liquid guiding components. Detailed Implementation

[0029] The following drawings disclose several embodiments of the present invention. For clarity, many practical details will be described in the following description. However, it should be understood that these practical details are not intended to limit the invention. That is, in some embodiments of the invention, these practical details are not essential. Furthermore, for the sake of simplicity, some conventional structures and components will be shown in the drawings in a simple schematic manner.

[0030] It should be noted that all directional indications in the embodiments of the present invention, such as up, down, left, right, front, back, etc., are only used to explain the relative positional relationship and movement of the components in a specific posture as shown in the attached figure. If the specific posture changes, the directional indication will also change accordingly.

[0031] Furthermore, in this invention, the use of terms such as "first" and "second" is for descriptive purposes only and does not specifically refer to any order or sequence, nor is it intended to limit the invention. They are merely used to distinguish components or operations described using the same technical terms, and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of various embodiments can be combined with each other, but only if they are feasible for those skilled in the art. If a combination of technical solutions is contradictory or impossible to implement, such a combination should be considered nonexistent and not within the scope of protection claimed by this invention.

[0032] Example 1

[0033] Reference Figure 1 , Figure 1 This is a schematic diagram of the structure of a lithium-ion battery in this embodiment. A lithium-ion battery in this embodiment includes a casing 1, a liquid guiding component 2, and a battery cell 3. The casing 1 has a receiving cavity, and the liquid guiding component 2 and the battery cell 3 are respectively disposed in the receiving cavity. The liquid guiding component 2 is located between the casing 1 and the battery cell 3. The liquid guiding component 2 is used to conduct electrolyte, thereby driving the electrolyte to circulate in the receiving cavity.

[0034] By setting a liquid guide 2 between the outer casing 1 and the cell 3, the liquid guide 2 is used to conduct the electrolyte, leading the electrolyte from the bottom to the top of the battery, thereby keeping the electrolyte inside the cell 3. This avoids the situation where the electrolyte is lost after multiple battery cycles, and the electrolyte cannot be transported normally due to gravity, resulting in a lack of electrolyte in the upper part of the cell 3 and lithium deposition. This effectively improves the battery cycle performance and extends the battery life.

[0035] The liquid guiding component 2 is tightly attached to the inner wall of the outer casing 1 on one side and to the side of the battery cell 3 on the other side, thereby ensuring that the liquid guiding component 2 fully fills the gap between the outer casing 1 and the battery cell 3. The liquid guiding component 2 has excellent chemical stability, wettability, thermal stability, and porosity, thereby maintaining the electrolyte retention inside the battery cell 3. Specifically, the liquid guiding component 2 includes at least one of a capillary tube, a fiber tube, and a diaphragm. Preferably, the diaphragm is a PP diaphragm or an aromatic polyamide (PMIA) diaphragm.

[0036] Preferably, the liquid guiding component 2 comprises multiple PP diaphragms and multiple capillaries mixed together, and the total volume ratio of the multiple PP diaphragms and multiple capillaries is 1:(0.5-2); or the liquid guiding component 2 comprises multiple PP diaphragms and multiple fiber tubes mixed together, and the volume ratio of the multiple PP diaphragms and multiple fiber tubes is 1:(0.5-2). In practical applications, the PP diaphragms, capillaries, and fiber tubes are all in a broken state. The PP diaphragms with low porosity have good electrolyte storage properties, and the capillaries and fiber tubes exhibit capillary action, immersing themselves in the electrolyte, allowing the electrolyte to overcome gravity and move upward or downward, resulting in good electrolyte transport performance. The liquid guiding component 2 is made by combining a PP separator with a capillary or fiber tube. This gives the liquid guiding component 2 both the good electrolyte storage properties of the PP separator and the good electrolyte transport properties of the capillary or fiber tube. During battery use, the expansion and contraction cycle of the cell 3 squeezes the PP separator. After being squeezed, the PP separator releases the electrolyte stored inside. Then, the capillary or fiber tube transports the electrolyte, thereby ensuring the circulation of the electrolyte, further improving the battery cycle performance and extending the battery life.

[0037] Cell 3 is a wound cell. Perpendicular to the winding direction of cell 3, the height of the liquid guiding component 2 is not lower than the height of cell 3, thus ensuring that the liquid guiding component 2 can transfer electrolyte between the bottom and top of cell 3, guaranteeing the wetting effect of cell 3. In specific applications, cell 3 is a lithium iron phosphate cell, lithium manganese oxide cell, lithium cobalt oxide cell, or ternary nickel-cobalt-manganese lithium oxide cell. Cell 3 can be a cylindrical cell or a prismatic cell. The battery in this application can be made into cells of different materials and shapes, possessing versatility.

[0038] By setting a liquid guide 2 between the outer casing 1 and the cell 3, the liquid guide 2 has good electrolyte storage and electrolyte transport properties, which can guide the electrolyte from the bottom to the top of the battery, thereby keeping the electrolyte inside the cell 3. This avoids the situation where the electrolyte is lost after multiple cycles and cannot be transported normally due to gravity, resulting in a lack of electrolyte in the upper part of the cell 3 and lithium deposition. This effectively improves the battery cycle performance and extends the battery life.

[0039] Example 2

[0040] This embodiment describes a method for preparing a lithium-ion battery, used to prepare the lithium-ion battery in Example 1, comprising the following steps:

[0041] S1: The liquid guiding component 2 is placed in the receiving cavity of the outer shell 1.

[0042] S2: The cell 3 is placed in the receiving cavity of the outer casing 1, and the liquid guiding component 2 is located between the cell 3 and the outer casing 1 to obtain a pre-fabricated liquid guiding battery.

[0043] S3: The prefabricated battery undergoes liquid injection, sealing, formation, settling, and capacity testing to obtain a lithium-ion battery.

[0044] Preferably, before step S1, the following sub-steps are also included:

[0045] S0: At least one of the following pre-designed liquid guiding components 2: capillary tube, fiber tube, and diaphragm.

[0046] Specifically, a PP diaphragm and capillary tube with a total volume ratio of 1:(0.5-2) are crushed and mixed to obtain liquid-conducting component 2. Alternatively, a PP diaphragm and fiber tube with a total volume ratio of 1:(0.5-2) are crushed and mixed to obtain liquid-conducting component 2. The PP diaphragm with low porosity has good electrolyte storage properties, while the capillary tube and fiber tube exhibit capillary action, allowing the electrolyte to rise or fall against gravity, resulting in good electrolyte transport performance. The liquid guiding component 2 is made by combining a PP separator with a capillary or fiber tube. This gives the liquid guiding component 2 both the good electrolyte storage properties of the PP separator and the good electrolyte transport properties of the capillary or fiber tube. During battery use, the expansion and contraction cycle of the cell 3 squeezes the PP separator. After being squeezed, the PP separator releases the electrolyte stored inside. Then, the capillary or fiber tube transports the electrolyte, thereby ensuring the circulation of the electrolyte, further improving the battery cycle performance and extending the battery life.

[0047] Preferably, in step S1, the liquid guiding component 2 is closely attached to the inner wall of the outer casing 1, and it is necessary to ensure that the liquid guiding component 2 completely covers the inner wall of the outer casing 1, thereby ensuring that the height of the liquid guiding component 2 is not lower than the height of the battery cell 3, and ensuring that in subsequent steps, the liquid guiding component 2 can fully fill the gap between the outer casing 1 and the battery cell 3.

[0048] Preferably, in step S2, when the battery cell 3 is placed inside the liquid guiding component 2, it is necessary to ensure that the liquid guiding component 2 fully fills the gap between the outer casing 1 and the battery cell 3.

[0049] Example 3

[0050] Reference Figure 2 , Figure 2 This is a schematic diagram of the battery module structure in the embodiment. A battery module includes the lithium-ion battery in Embodiment 1. In practical applications, the battery module includes multiple lithium-ion batteries.

[0051] To further understand the invention's content, features, and effects, the following embodiments are provided, and detailed descriptions are given below in conjunction with the accompanying drawings:

[0052] Example

[0053] Lithium-ion batteries were prepared using the methods described in Example 2, comprising aromatic polyamide (PMIA), capillary tubes, fiber tubes, PP membranes, capillary tubes and PP membranes, and fiber tubes and PP membranes, respectively. In the combination of capillary tubes and PP membranes, the volume ratio of capillary tubes to PP membranes was 1:1; in the combination of fiber tubes and PP membranes, the volume ratio of fiber tubes to PP membranes was also 1:1. The performance of these batteries was then tested, and the test results are as follows: Figures 3-8 As shown, Figure 3 The graph shows the cycle performance test results of a battery using polyamide as the liquid guiding component. Figure 4 The graph shows the cycle performance test results of a battery with a PP separator as the liquid guiding component. Figure 4 This is a test diagram of the cycle performance of a battery using a fiber tube as the liquid guiding component. Figure 4 This is a graph showing the cycle performance test of a battery using a capillary tube as the liquid guiding element. Figure 4 This is a test chart showing the cycle performance of a battery using a PP separator and fiber tube as the liquid guiding components. Figure 4 This is a test chart of the cycle performance of a battery with a PP separator and capillary tube as the liquid guiding components.

[0054] Depend on Figures 3-8It is evident that lithium-ion batteries with added liquid guiding components exhibit significantly improved cycle performance compared to those without. This is particularly true when the liquid guiding component is a combination of capillary tube and PP membrane, or a combination of fiber tube and PP membrane, resulting in the best cycle performance. After 700 cycles, the battery capacity retention rate remains above 80%. This is because the low porosity of the PP membrane provides excellent electrolyte storage, while the capillary tube and fiber tube exhibit capillary action, resulting in good electrolyte transport performance. By combining a PP membrane with a capillary tube or fiber tube to create the liquid guiding component 2, the component combines the excellent electrolyte storage properties of the PP membrane with the excellent electrolyte transport performance of the capillary tube or fiber tube.

[0055] In summary, the lithium-ion battery of this application, by setting a liquid guiding component between the casing and the cell, conducts the electrolyte from the bottom to the top of the battery, thereby maintaining electrolyte retention inside the cell. This avoids the situation where, after multiple battery cycles, electrolyte loss occurs and gravity prevents normal electrolyte transport, leading to lithium deposition due to insufficient electrolyte in the upper part of the cell. This effectively improves battery cycle performance and extends battery life.

[0056] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A lithium-ion battery, characterized in that, The device includes a housing (1), a liquid guide (2), and a battery cell (3). The housing (1) has a receiving cavity. The liquid guide (2) and the battery cell (3) are respectively disposed in the receiving cavity. The liquid guide (2) is located between the housing (1) and the battery cell (3). One side of the liquid guide (2) is in close contact with the inner wall of the housing (1), and the other side is in close contact with the side of the battery cell (3). The liquid guide (2) is used to conduct electrolyte, thereby driving the electrolyte to circulate in the receiving cavity. The liquid guiding component (2) includes multiple diaphragms and multiple capillaries mixed together, and the total volume ratio of the multiple diaphragms and multiple capillaries is 1:(0.5-2); the diaphragms are PP diaphragms, and both the PP diaphragms and the capillaries are in a broken state.

2. The lithium-ion battery according to claim 1, characterized in that, The battery cell (3) is a wound battery cell, and the height of the liquid guiding component (2) is not lower than the height of the battery cell (3).

3. The lithium-ion battery according to claim 1, characterized in that, The battery cell (3) is a lithium iron phosphate battery cell, a lithium manganese oxide battery cell, a lithium cobalt oxide battery cell, or a ternary nickel cobalt manganese oxide battery cell.

4. A method for preparing a lithium-ion battery according to any one of claims 1-3, characterized in that, Includes the following steps: The liquid guiding component (2) is placed in the receiving cavity of the outer shell (1); wherein, the liquid guiding component (2) includes a plurality of diaphragms and a plurality of capillaries mixed together, and the total volume ratio of the plurality of diaphragms and the plurality of capillaries is 1:(0.5-2); the diaphragms are PP diaphragms, and the PP diaphragms and capillaries are in a broken state; The battery cell (3) is placed in the receiving cavity of the outer casing (1), and the liquid guiding component (2) is located between the battery cell (3) and the outer casing (1) to obtain a prefabricated battery; The prefabricated battery is subjected to liquid injection, sealing, formation, settling, and capacity testing to obtain a lithium-ion battery.

5. A battery module, characterized in that, Includes the lithium-ion battery as described in any one of claims 1-3.

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