Battery capable of prolonging cycle life

Abstract

The utility model discloses a battery capable of prolonging the cycle life, and relates to the field of rechargeable batteries. The battery cell adopts the structure that the positive plates and the negative plates are alternately stacked, the diaphragms are arranged between the positive plates and the negative plates, the diaphragms arranged in the upper-layer diaphragm area and the lower-layer diaphragm area of the battery cell are the first diaphragms, the diaphragm arranged in the middle diaphragm area of the battery cell is the second diaphragm, and the thickness of the second diaphragm is larger than that of the first diaphragms. Therefore, the thickness of the diaphragm at the middle position of the battery cell is thicker, the thickness of the diaphragm at other positions of the battery cell can support ultra-thin design, meanwhile, electrolyte stored in the second diaphragm can flow back into the battery again and provide conducting ions in the actual use process, the electrolyte is more uniformly distributed in the battery, and the service life of the battery is prolonged. Therefore, the time of black spot generation and lithium precipitation of the pole piece is delayed, the cycle life of the battery is greatly prolonged, and the battery can have high power, high energy density, long cycle life and high safety on the whole.

Description

Technical Field

[0001] The utility model relates to the field of rechargeable batteries, in particular to a battery capable of extending the cycle life. Background Art

[0002] Lithium battery is a rechargeable battery technology that uses lithium metal or lithium ion compounds as electrode materials. Lithium batteries have become the preferred power source for portable electronic devices, electric vehicles and energy storage systems due to their high energy density, long cycle life, low self-discharge rate and environmental adaptability.

[0003] The main components of lithium batteries include an external insulating package, as well as a positive electrode material, a negative electrode material, a separator and an electrolyte arranged in the external insulating package. Among them, the separator is used to separate the positive and negative electrodes to prevent short circuits, and the separator can hold the electrolyte to allow lithium ions to pass through. When charging, lithium ions are released from the positive electrode and move to the negative electrode through the electrolyte. When discharging, the process is reversed, and lithium ions are released from the negative electrode and return to the positive electrode.

[0004] The power, energy density and cycle life of lithium-ion batteries are three key indicators of battery performance, and there is a relationship of mutual influence and restriction among them. With the increasing market requirements for maximum battery power and energy density, manufacturers have adopted ultra-thin diaphragm designs in order to meet market demand, so that the battery per unit volume can provide higher power and more energy. However, as the thickness of the diaphragm decreases, the battery's liquid retention performance will also decrease, making it difficult to maintain a stable supply of electrolyte during the charge and discharge process, and the loss of electrolyte will lead to a shortened cycle life. Existing battery application fields require that the battery cycle life is 1000-2000 times, and the lower requirement is 500 times. Existing batteries with ultra-thin diaphragm designs often cannot meet the requirements.

[0005] In summary, the ultra-thin diaphragm design of lithium batteries currently used has improved the power and energy density to a certain extent, but there is a problem of reduced battery cycle life caused by reduced liquid retention. Utility Model Content

[0006] In order to solve the problems existing in the prior art, the main purpose of the utility model is to provide a battery with a prolonged cycle life. On the basis of thinning the overall diaphragm thickness, the battery's liquid retention performance is improved, thereby extending the cycle life, so that the battery can have high power, high energy density and a longer cycle life.

[0007] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0008] A battery capable of extending the cycle life comprises a battery cell, wherein the battery cell comprises a plurality of positive electrode sheets and negative electrode sheets alternately stacked, and a separator arranged between any adjacent positive electrode sheets and negative electrode sheets;

[0009] The battery cell can be divided into an upper diaphragm area, a middle diaphragm area and a lower diaphragm area according to the relative stacking positions of the diaphragms. The upper diaphragm area and the lower diaphragm area are respectively configured with at least one first diaphragm, and the middle diaphragm area is configured with at least one second diaphragm, and the thickness of the second diaphragm is greater than the thickness of the first diaphragm.

[0010] Optionally, each of the positive electrode sheets in the middle diaphragm region is respectively wrapped and arranged in a second diaphragm bag composed of two layers of second diaphragms; each of the positive electrode sheets in the upper diaphragm region and the lower diaphragm region is respectively wrapped and arranged in a first diaphragm bag composed of two layers of first diaphragms;

[0011] A positive electrode sheet wrapped with a second diaphragm bag is arranged between any two adjacent negative electrode sheets in the middle diaphragm area, and a positive electrode sheet wrapped with a first diaphragm bag is arranged between any two adjacent negative electrode sheets in the upper diaphragm area and the lower diaphragm area.

[0012] Optionally, the number of positive electrode sheets in the middle separator area does not exceed 30% of the total number of positive electrode sheets.

[0013] Optionally, the total number of the positive electrode sheets is not less than 10.

[0014] Optionally, the thickness of the second diaphragm is not less than 1.5 times the thickness of the first diaphragm.

[0015] Optionally, the thickness of the second diaphragm is not greater than 3 times the thickness of the first diaphragm.

[0016] Optionally, the number of the positive electrode sheets in the upper diaphragm region is equal to the number of the positive electrode sheets in the lower diaphragm region.

[0017] Optionally, all the positive electrode sheets have the same shape and structure, and all the negative electrode sheets have the same shape and structure.

[0018] Optionally, the negative electrode sheet is composed of a negative electrode current collecting substrate coated with a negative electrode material; the topmost negative electrode sheet is coated with negative electrode material only on the lower side, the bottommost negative electrode sheet is coated with negative electrode material only on the upper side, and the remaining negative electrode sheets are coated with negative electrode material on both sides.

[0019] Optionally, each of the positive electrode sheets is composed of a positive electrode current collecting substrate coated with a positive electrode material, and a negative electrode extension portion is provided at the edge of each of the negative electrode current collecting substrates, and each of the negative electrode extension portions is welded to each other and electrically connected to the negative electrode of the battery; and a positive electrode extension portion is provided at the edge of each of the positive electrode current collecting substrates, and each of the positive electrode extension portions is welded to each other and electrically connected to the positive electrode of the battery.

[0020] Compared with the prior art, the utility model has the following beneficial effects:

[0021] The battery cell of the utility model adopts an alternating stacking structure of positive and negative electrode sheets, and a diaphragm is arranged between the positive and negative electrode sheets. The diaphragms configured in the upper and lower diaphragm areas of the battery cell are the first diaphragms, and the diaphragm configured in the middle diaphragm area of ​​the battery cell is the second diaphragm. The thickness of the second diaphragm is greater than that of the first diaphragm, so that the thickness of the diaphragm in the middle position of the battery cell is thicker, and the thickness of the diaphragm in other positions of the battery cell can support ultra-thin design. At the same time, during actual use, the electrolyte stored in the second diaphragm can flow back into the battery and provide conducting ions. The electrolyte is more evenly distributed in the battery, thereby delaying the time for black spots and lithium precipitation on the electrode sheets, greatly extending the cycle life of the battery. Overall, the battery can take into account high power, high energy density, long cycle life and high safety, making the battery more popular in the market.

[0022] The utility model is further described below in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic cross-sectional structure diagram of a battery capable of extending cycle life according to a first embodiment of the utility model;

[0024] Figure 2 A schematic diagram of a three-dimensional cross-sectional structure of a battery capable of extending cycle life according to a second embodiment of the utility model;

[0025] Figure 3 According to the utility model Figure 2 A schematic diagram of a three-dimensional cross-sectional structure of a local A enlarged;

[0026] Figure 4 A schematic three-dimensional cross-sectional structure diagram of a battery capable of extending cycle life according to a third embodiment of the utility model.

[0027] Figure numerals: 10, battery cell; 101, upper diaphragm area; 102, middle diaphragm area; 103, lower diaphragm area; 20, insulating shell; 30, positive battery terminal; 40, negative battery terminal; 11, positive electrode sheet; 111, positive electrode extension; 12, negative electrode sheet; 121, negative electrode extension; 13, first diaphragm; 131, first diaphragm bag; 14, second diaphragm; 141, second diaphragm bag. DETAILED DESCRIPTION

[0028] In order to better illustrate the purpose, technical solution and advantages of the utility model, the specific implementation of the utility model is further described in detail below in conjunction with the drawings and embodiments. The following embodiments are used to illustrate the utility model, but are not intended to limit the scope of the utility model.

[0029] like Figure 1 As shown, a battery with extended cycle life according to the first embodiment of the utility model. In the first embodiment, the battery includes a battery cell 10, an insulating shell 20, a battery positive terminal 30 and a battery negative terminal 40. The battery cell 10 is disposed in the insulating shell 20, and 21 positive electrode sheets 11 and 22 negative electrode sheets 12 are disposed in the battery cell 10, and each positive electrode sheet 11 and each negative electrode sheet 12 are alternately stacked. For example, the battery cell 10 is configured with a negative electrode sheet 12, a positive electrode sheet 11, a negative electrode sheet 12, ..., a positive electrode sheet 11, and a negative electrode sheet 12 stacked in sequence.

[0030] A diaphragm is provided between any adjacent positive electrode sheet 11 and negative electrode sheet 12, so that the diaphragm separates the positive electrode sheet 11 and the negative electrode sheet 12 to prevent short circuit. Each positive electrode sheet 11 is respectively conductively connected to the positive terminal 30 of the battery, and each negative electrode sheet 12 is respectively conductively connected to the negative terminal 40 of the battery. The insulating shell 20 is also filled with an electrolyte, and the electrolyte can penetrate into each diaphragm, thereby realizing the charge and discharge between the positive electrode sheet 11 and the negative electrode sheet 12.

[0031] In order to provide a separator between the adjacent positive electrode sheets 11 and negative electrode sheets 12, in this embodiment, 42 layers of separators are provided. According to the relative positions of each separator in the stacking direction, the battery cell 10 can be divided into an upper separator area 101, a middle separator area 102 and a lower separator area 103. The upper separator area 101 is located on the upper side of the middle separator area 102, and the lower separator area 103 is located on the lower side of the middle separator area 102. The separators configured in the upper separator area 101 and the lower separator area 103 are the first separators 13. The separator configured in the middle separator area 102 is the second separator 14. The first separator 13 of the upper separator area 101 is configured with 17 layers. The first separator 13 of the lower separator area 103 is configured with 17 layers. The second separator 14 of the middle separator area 102 is configured with 8 layers. The thickness of the second diaphragm 14 of each middle diaphragm area 102 is equal. The thickness of the first diaphragm 13 of each upper diaphragm area 101 and lower diaphragm area 103 is equal. The thickness of the second diaphragm 14 is greater than the thickness of the first diaphragm 13. The thickness of the first diaphragm 13 can be designed according to the thickness of the ultra-thin diaphragm, and the thickness of the second diaphragm 14 can be thickened on the basis of the thickness of the first diaphragm 13.

[0032] It can be seen that since the first diaphragm 13 in the upper and lower areas is designed to be ultra-thin, the battery can achieve high power and high energy density. The second diaphragm 14 in the middle area is designed to be thickened so that the electrolyte in the middle can flow back when the battery is in use and provide conductive ions. The actual distribution of the electrolyte in the battery is more uniform, so that the battery has the characteristics of long cycle life and high safety.

[0033] like Figure 2 and Figure 3 As shown, a battery cell 10 of a battery capable of extending the cycle life according to the second embodiment of the utility model is provided. A plurality of positive electrode sheets 11 and a plurality of negative electrode sheets 12 are arranged in the battery cell 10. The positive electrode sheets 11 and the negative electrode sheets 12 are arranged in an alternating stacking manner. A diaphragm is arranged between any adjacent positive electrode sheets 11 and negative electrode sheets 12. According to the relative position of each diaphragm in the stacking direction, the battery cell 10 can be divided into an upper diaphragm area 101, a middle diaphragm area 102 and a lower diaphragm area 103. The diaphragms arranged in the upper diaphragm area 101 and the lower diaphragm area 103 are the first diaphragms 13. The diaphragm arranged in the middle diaphragm area 102 is the second diaphragm 14.

[0034] Specifically, each positive electrode sheet 11 of the middle diaphragm area 102 is respectively wrapped and set in a second diaphragm bag 141 composed of two layers of second diaphragms 14. Each negative electrode sheet 12 of the middle diaphragm area 102 is a bare electrode sheet and is not wrapped with a diaphragm. In the middle diaphragm area 102, the positive electrode sheets 11 wrapped with the second diaphragm bag 141 and the unwrapped negative electrode sheets 12 are alternately stacked, but the second diaphragm 14 is set between any adjacent positive electrode sheets 11 and negative electrode sheets 12. Similarly, in the upper diaphragm area 101 and the lower diaphragm area 103, each positive electrode sheet 11 is respectively wrapped and set in a first diaphragm bag 131 composed of two layers of first diaphragms 13. After the positive electrode sheets 11 and the negative electrode sheets 12 are alternately stacked, the first diaphragm 13 is set between any adjacent positive electrode sheets 11 and negative electrode sheets 12. Specifically, taking the first diaphragm bag 131 as an example and the second diaphragm bag 141 in the same manner, the first diaphragm bag 131 is formed by bonding two first diaphragms 13 along the contour of the positive electrode sheet 11 , so that the first diaphragm bag 131 has a cavity inside to accommodate the positive electrode sheet 11 .

[0035] It is worth noting that by wrapping the positive electrode sheet 11 of the upper diaphragm area 101 and the lower diaphragm area 103 in the first diaphragm 13, and wrapping the positive electrode sheet 11 of the middle diaphragm area 102 in the second diaphragm 14, the process of diaphragm stacking is reduced during the stacking process, so that the battery production efficiency is improved. The diaphragm coating of the positive electrode sheet 11 can prevent the positive electrode material from falling off during the manufacturing and use of the battery, and reduce the risk of internal short circuit of the battery. At the same time, the diaphragm coating of the positive electrode sheet 11 helps to maintain the structural stability of the positive electrode material, further improve the cycle life and energy density of the battery, and avoid the influence of the increased thickness of the second diaphragm 14 on the energy density.

[0036] like Figure 4 As shown, a battery cell 10 of a battery capable of extending the cycle life according to the third embodiment of the utility model is provided. The battery cell 10 is provided with a positive electrode sheet 11 wrapped in a first diaphragm bag 131, a positive electrode sheet 11 wrapped in a second diaphragm bag 141, and a negative electrode sheet 12. In the middle diaphragm region 102, there are two positive electrode sheets 11 wrapped in the second diaphragm bag 141, or more than two. A negative electrode sheet 12 is provided between the two positive electrode sheets 11 wrapped in the second diaphragm bag 141. On the uppermost positive electrode sheet 11 wrapped in the second diaphragm bag 141 in the middle diaphragm region 102, a plurality of negative electrode sheets 12 and a plurality of positive electrode sheets 11 wrapped in the first diaphragm bag 131 are alternately stacked, thereby forming an upper diaphragm region 101. Under the positive electrode sheet 11 wrapped in the second diaphragm bag 141 at the bottom of the middle diaphragm area 102, multiple negative electrode sheets 12 and multiple positive electrode sheets 11 wrapped in the first diaphragm bag 131 are alternately stacked, thereby forming a lower diaphragm area 103. The thickness of the upper and lower diaphragms of the second diaphragm bag 141 is greater than the thickness of the upper diaphragm of the first diaphragm bag 131. After stacking, the battery of this embodiment can be formed.

[0037] According to various embodiments of the utility model, specifically, the number of positive electrode sheets 11 in the middle diaphragm area 102 does not exceed 30% of the total number of positive electrode sheets 11. Taking the first embodiment as an example, the number of positive electrode sheets 11 is 21, and the number of positive electrode sheets 11 in the middle diaphragm area 102 is 5 (rounded), and the number of positive electrode sheets 11 in the middle diaphragm area 102 is 23.8% of the total number of positive electrode sheets 11, which does not exceed 30%, so that only the middle quarter of the battery cell 10 is set as the second diaphragm 14 with thickened thickness, thereby reducing the impact on the overall energy density of the battery. In various embodiments, the total number of positive electrode sheets 11 can be configured to be no less than 10. In batteries with a large number of positive electrode sheets 11, negative electrode sheets 12 and diaphragm layers, the thickening of the diaphragm in the middle area can better extend the cycle life of the battery without affecting the overall energy density.

[0038] According to various embodiments of the present invention, specifically, the thickness of the second diaphragm 14 is between 1.5 and 3 times the thickness of the first diaphragm 13. For example, the thickness of the second diaphragm 14 is set to be 2 times that of the first diaphragm 13, which can effectively increase the liquid retention in the middle area of ​​the battery while maintaining the overall energy density at a high level.

[0039] According to various embodiments of the present invention, specifically, in conventional battery processes, all positive electrode sheets 11 have the same shape and structure, and all negative electrode sheets 12 have the same shape and structure. Specifically, the battery of the present invention is in the shape of a rectangular parallelepiped, and the number of positive electrode sheets 11 in the upper diaphragm area 101 is equal to the number of positive electrode sheets 11 in the lower diaphragm area 103, so that the second diaphragm 14 that can increase the liquid retention capacity is concentrated in the middle position of the battery. In other embodiments, the battery of the present invention is configured as an irregular shape, and the number of positive electrode sheets 11 in the upper diaphragm area 101 and the lower diaphragm area 103 can be configured to be different.

[0040] According to various embodiments of the utility model, specifically, in a conventional battery process, the positive electrode sheet 11 is composed of a positive electrode current collecting substrate coated with a positive electrode material on both sides, and a positive electrode extension 111 is provided at the edge of the positive electrode current collecting substrate. Similarly, the negative electrode sheet 12 is composed of a negative electrode current collecting substrate coated with a negative electrode material, and a negative electrode extension 121 is provided at the edge of the negative electrode current collecting substrate. The shape of the positive electrode current collecting substrate is substantially the same as that of the negative electrode current collecting substrate, such as a rectangle with similar length and width. The positive electrode extension 111 and the negative electrode extension 121 extend to different positions after the positive electrode sheet 11 and the negative electrode sheet 12 are stacked. In the battery cell 10, each positive electrode extension 111 is welded to each other and electrically connected to the positive terminal 30 of the battery, and each negative electrode extension 121 is welded to each other and electrically connected to the negative terminal 40 of the battery.

[0041] In this embodiment, the number of negative electrode sheets 12 is one layer more than the number of positive electrode sheets 11. In other words, whether it is the top layer or the bottom layer, the negative electrode sheet 12 is the closest to the insulating shell of the battery cell 10. For this reason, the negative electrode sheet 12 of the top layer is coated with negative electrode material only on the lower side, the negative electrode sheet 12 of the bottom layer is coated with negative electrode material only on the upper side, and the remaining negative electrode sheets 12 are coated with negative electrode material on both sides. In this way, the negative electrode materials of the top and bottom negative electrode sheets 12 are prevented from contacting the insulating shell, thereby improving the safety of the battery.

[0042] The above embodiments mainly describe the basic principles, main features and advantages of the utility model. Those skilled in the art should understand that the utility model is not limited by the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the utility model. Without departing from the spirit and scope of the utility model, the utility model may have various changes and improvements, and these changes and improvements fall within the scope of the utility model to be protected.

Claims

1. A battery capable of extending cycle life, comprising a battery cell (10), characterized in that: The battery cell (10) comprises a plurality of positive electrode sheets (11) and negative electrode sheets (12) alternately stacked, and a separator arranged between any adjacent positive electrode sheets (11) and negative electrode sheets (12); The battery cell (10) can be divided into an upper diaphragm region (101), a middle diaphragm region (102) and a lower diaphragm region (103) according to the relative stacking positions of the diaphragms; the upper diaphragm region (101) and the lower diaphragm region (103) are respectively provided with at least one first diaphragm (13); the middle diaphragm region (102) is provided with at least one second diaphragm (14); the thickness of the second diaphragm (14) is greater than the thickness of the first diaphragm (13).

2. A battery with a prolonged cycle life according to claim 1, characterized in that: Each of the positive electrode sheets (11) in the middle diaphragm region (102) is respectively wrapped and arranged in a second diaphragm bag (141) composed of two layers of second diaphragms (14); each of the positive electrode sheets (11) in the upper diaphragm region (101) and the lower diaphragm region (103) is respectively wrapped and arranged in a first diaphragm bag (131) composed of two layers of first diaphragms (13); A positive electrode sheet (11) wrapped with a second diaphragm bag (141) is arranged between any two adjacent negative electrode sheets (12) in the middle diaphragm area (102), and a positive electrode sheet (11) wrapped with a first diaphragm bag (131) is arranged between any two adjacent negative electrode sheets (12) in the upper diaphragm area (101) and the lower diaphragm area (103).

3. A battery with a prolonged cycle life according to claim 1, characterized in that: The number of positive electrode sheets (11) in the middle diaphragm region (102) does not exceed 30% of the total number of positive electrode sheets (11).

4. A battery with a prolonged cycle life according to claim 3, characterized in that: The total number of the positive electrode sheets (11) is not less than 10.

5. A battery with a prolonged cycle life according to claim 1, characterized in that: The thickness of the second diaphragm (14) is not less than 1.5 times the thickness of the first diaphragm (13).

6. A battery with a prolonged cycle life according to claim 5, characterized in that: The thickness of the second diaphragm (14) is not greater than 3 times the thickness of the first diaphragm (13).

7. A battery with a prolonged cycle life according to claim 1, characterized in that: The number of the positive electrode sheets (11) in the upper diaphragm region (101) is equal to the number of the positive electrode sheets (11) in the lower diaphragm region (103).

8. A battery with a prolonged cycle life according to claim 1, characterized in that: All of the positive electrode sheets (11) have the same shape and structure, and all of the negative electrode sheets (12) have the same shape and structure.

9. A battery with a prolonged cycle life according to claim 1, characterized in that: The negative electrode sheet (12) is composed of a negative electrode current collecting substrate coated with a negative electrode material; the negative electrode sheet (12) at the top layer is coated with the negative electrode material only on the lower side, the negative electrode sheet (12) at the bottom layer is coated with the negative electrode material only on the upper side, and the remaining negative electrode sheets (12) are coated with the negative electrode material on both sides.

10. A battery with a prolonged cycle life according to claim 9, characterized in that: Each of the positive electrode sheets (11) is composed of a positive electrode current collecting substrate coated with a positive electrode material; the edge of each of the negative electrode current collecting substrates is provided with a negative electrode extension portion (121), and each of the negative electrode extension portions (121) are welded to each other and electrically connected to the negative electrode of the battery; the edge of each of the positive electrode current collecting substrates is provided with a positive electrode extension portion (111), and each of the positive electrode extension portions (111) are welded to each other and electrically connected to the positive electrode of the battery.

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