Patent Application
20240339734
This application relates to the technical field of energy storage, and in particular, to an electrochemical device, a battery module, and an electrical device.
By virtue of a high specific energy, reusability for a large number of cycles, a long storage time, and other advantages, lithium-ion batteries are widely used not only in portable electronic devices such as mobile phones, digital cameras, and laptop computers, but also in large and medium-sized electrical devices such as electric vehicles, electric bicycles, and electric tools.
During charging and discharging of a lithium-ion battery, Li+ ions are shuttled between a positive electrode and a negative electrode by intercalation and deintercalation. During charging, Li+ ions are deintercalated from the positive electrode and intercalated into the negative electrode through an electrolyte. The negative electrode is in a lithium-rich state. During discharging, the contrary applies.
In a process of implementing this application, the applicant hereof finds that, in the field of new energy vehicles, a higher energy density, higher C-rate performance, a long life, and safety have imposed higher requirements on the lithium-ion batteries. With the increase of the energy density, the size of the battery increases, and a single tab serving as a terminal for inputting and outputting electrical energy between the battery and an external device can hardly meet the higher C-rate performance requirement. Therefore, a multi-tab structure is introduced. However, with the design of the multi-tab structure, at a later stage of long-term cycling of the battery, lithium plating is prone to occur inside the battery after the electrolyte solution is depleted, thereby resulting in a lifespan decline and safety hazards, and hindering widespread popularization.
In view of the above problems, some embodiments of this application provide an electrochemical device, a battery module, and an electrical device to alleviate the problems such as lithium plating of the battery.
According to one aspect of some embodiments of this application, an electrochemical device is provided. The electrochemical device includes an electrode assembly. The electrode assembly includes a first electrode plate, a second electrode plate, and a separator. A plurality of first tabs are disposed on the first electrode plate. The separator is disposed between the first electrode plate and the second electrode plate. The first electrode plate, the separator, and the second electrode plate are stacked and wound. In addition, the plurality of first tabs are connected to a region of the first electrode plate other than first inner layers and first outer layers. The first inner layers include N layers starting from a start layer of the first electrode plate along a direction from the start layer to an end layer of the first electrode plate. The first outer layers include M layers starting from the end layer of the first electrode plate along a direction from the end layer to the start layer of the first electrode plate, where M≥1, and N≥3. By setting the distribution positions of the first tabs, the electromotive force at the first inner layers and the first outer layers of the first electrode plate is reduced during charging and discharging of the electrochemical device, and the speed of lithiation at a local region is reduced, thereby alleviating lithium plating of the battery.
In an optional manner, the first electrode plate includes a first current collector. The plurality of first tabs are formed by extending the first current collector from one side. The plurality of first tabs and the first current collector are formed in one piece. This arrangement facilitates the flow of a current between the first tab and the first current collector, and improves the distribution of the current density.
In an optional manner, a plurality of second tabs are disposed on the second electrode plate. The plurality of second tabs are connected to a region of the second electrode plate other than second inner layers and second outer layers. The second inner layers include K layers starting from a start layer of the second electrode plate along a direction from the start layer to an end layer of the second electrode plate, and the second outer layers include L layers starting from the end layer of the second electrode plate along a direction from the end layer to the start layer of the second electrode plate, where L≥1, and K≥3. By setting the distribution positions of the second tabs, the electromotive force at the second inner layers and the second outer layers of the second electrode plate is reduced during charging and discharging of the electrochemical device, and the speed of lithiation at a local region is reduced, thereby alleviating lithium plating of the battery.
In an optional manner, the second electrode plate includes a second current collector, the plurality of second tabs are formed by extending the second current collector from one side, and the plurality of second tabs and the second current collector are formed in one piece. This arrangement facilitates the flow of a current between the second tab and the second current collector, and improves the distribution of the current density.
In an optional manner, the first inner layers satisfy the following condition: 3≤N≤0.64, where N is an integer, and A is a total number of layers of the first electrode plate.
In an optional manner, the first outer layers satisfy the following condition: 1≤M≤0.6A, where M is an integer, and A is a total number of layers of the first electrode plate.
In an optional manner, at least one first tab is connected to each layer among the layers of the first electrode plate other than the first inner layers and the first outer layers.
In an optional manner, a number of first tabs connected to each layer among the layers of the first electrode plate other than the first inner layers and the first outer layers is not greater than 5. For example, the number of first tabs in each layer may be 1, 2, 3, 4, or 5.
In an optional manner, a total number of layers A of the first electrode plate is 5 to 80.
In an optional manner, the second inner layers satisfy the following condition: 3≤K≤0.6B, where K is an integer, and B is a total number of layers of the second electrode plate.
In an optional manner, the first outer layers satisfy the following condition: 1≤L≤0.6B, where L is an integer, and B is a total number of layers of the second electrode plate.
In an optional manner, at least one second tab is connected to each layer among the layers of the second electrode plate other than the second inner layers and the second outer layers.
In an optional manner, a number of second tabs connected to each layer among the layers of the second electrode plate other than the second inner layers and the second outer layers is not greater than 5. For example, the number of second tabs in each layer may be 1, 2, 3, 4, or 5.
In an optional manner, a total number of layers B of the second electrode plate is 5 to 80.
According to another aspect of some embodiments of this application, a battery module is provided. The battery module includes the electrochemical device disclosed above.
According to another aspect of some embodiments of this application, an electrical device is provided. The electrical device includes the battery module disclosed above.
The beneficial effects of some embodiments of this application are as follows: Different from the design in the prior art, an electrode assembly is disposed according to some embodiments of this application, and the electrode assembly includes a first electrode plate, a second electrode plate, and a separator; a plurality of first tabs are disposed on the first electrode plate; the separator is disposed between the first electrode plate and the second electrode plate; and the first electrode plate, the separator, and the second electrode plate are stacked and wound. In addition, the plurality of first tabs are connected to a region of the first electrode plate other than first inner layers and first outer layers; the first inner layers include N layers starting from a start layer of the first electrode plate along a direction from the start layer to an end layer of the first electrode plate; and the first outer layers include M layers starting from the end layer of the first electrode plate along a direction from the end layer to the start layer of the first electrode plate, where M≥1, and N≥3. By setting the distribution positions of the plurality of first tabs, the electromotive force at the first inner layers and the first outer layers of the first electrode plate is reduced during charging and discharging of the electrochemical device, and the speed of lithiation at a local region is reduced, thereby alleviating lithium plating of the battery.
To describe the technical solutions in the specific embodiments of this application or the prior art more clearly, the following outlines the drawings that need to be used in the descriptions of the specific embodiments of this application or the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. The elements or parts in the drawings are not necessarily drawn to scale.
For ease of understanding this application, the following describes this application in more detail with reference to drawings and specific embodiments. It is hereby noted that an element referred to herein as being “fixed to” another element may be directly disposed on the other element, or may be fixed to the other element with one or more elements in between. An element referred to herein as “connected to” another element may be connected to the other element directly or with one or more elements in between. The terms “vertical”, “horizontal”, “left”, “right”, and other similar expressions used herein are merely for ease of description.
Unless otherwise defined, all technical and scientific terms used herein bear the same meanings as what is normally understood by a person skilled in the technical field of this application. The terms used in the specification of this application are merely intended to describe specific embodiments but not to limit this application. The term “and/or” used herein is intended to include any and all combinations of one or more relevant items recited.
Referring to
With respect to the housing 10, as shown in
With respect to the electrode assembly 20, as shown in
A plurality of second tabs 205 are disposed on the second electrode plate 202. The second tab 205 is formed by extending the second electrode plate 202 from one side. One end, away from the second electrode plate 202, of the second tab 205 protrudes out of the housing 10.
In some embodiments, as shown in
In some embodiments, as shown in
In some embodiments, the first inner layers satisfy the following condition: 3≤N≤0.6A, where N is an integer, and A is the total number of layers of the first electrode plate 201. For example, when A=15, 3≤N≤9. In other words, in the direction from the start layer to the end layer of the first electrode plate 201, the first tab 204 is not disposed on at least 3 layers and at most 9 layers of the first electrode plate 201. If the value of N is equal to 5, then the first tab 204 is not disposed on the 1st layer to the 5th layer of the first electrode plate 201 in the direction from the start layer to the end layer of the first electrode plate 201.
In some embodiments, the first outer layers satisfy the following condition: 1≤M≤0.6A, where M is an integer, and A is the total number of layers of the first electrode plate 201. For example, when A=15, 1≤M≤9. In other words, in the direction from the end layer to the start layer of the first electrode plate 201, the first tab 204 is not disposed on at least 1 layer and at most 9 layers of the first electrode plate 201. If the value of M is equal to 3, then the first tab 204 is not disposed on the 1st layer (outermost layer) to the 3rd layer of the first electrode plate 201 in the direction from the end layer to the start layer of the first electrode plate 201.
In some embodiments, the total number of layers A of the first electrode plate 201 is 5 to 80.
It is hereby noted that the electrode assembly in this embodiment is a jelly-roll structure. In defining the total number of layers A of the first electrode plate 201, a layer from the first straight section unwound and located innermost in the electrode assembly to a midpoint of the first bend of the first electrode plate 201 is considered as a first fold of the first electrode plate and defined as a start layer of the first electrode plate 201; and, along the winding direction, a layer from the midpoint of the first bend to the midpoint of the second bend is considered as a second fold of the first electrode plate and defined as a second layer of the first electrode plate. In other words, each bend formed by the first electrode plate 201 makes the total number of layers of the first electrode plate 201 increase by 1. For other layers, the arrangement is deduced similarly.
For the second electrode plate 202, in some embodiments, as shown in
In some embodiments, as shown in
In some embodiments, the second inner layers satisfy the following condition: 3≤K≤0.6B, where K is an integer, and B is the total number of layers of the second electrode plate 202. For example, when B=15, 3≤K≤9. In other words, in the direction from the start layer to the end layer of the second electrode plate 202, the second tab 205 is not disposed on at least 3 layers and at most 9 layers of the second electrode plate 202. If the value of K is equal to 5, then the second tab 205 is not disposed on the 1st layer to the 5th layer of the second electrode plate 202 in the direction from the start layer to the end layer of the second electrode plate 202.
In some embodiments, the second outer layers satisfy the following condition: 1≤L≤0.6B, where L is an integer, and B is the total number of layers of the second electrode plate 202. For example, when B=15, 1≤L≤9. In other words, in the direction from the end layer to the start layer of the second electrode plate 202, the second tab 205 is not disposed on at least 1 layer and at most 9 layers of the second electrode plate 202. If the value of M is equal to 3, then the second tab 205 is not disposed on the 1st layer (outermost layer) to the 3rd layer of the second electrode plate 202 in the direction from the end layer to the start layer of the second electrode plate 202.
In some embodiments, the total number of layers B of the second electrode plate 202 is 5 to 80.
It is hereby noted that the electrode assembly in this embodiment is a jelly-roll structure. In defining the total number of layers B of the second electrode plate 202, a section from the first straight section unwound and located innermost in the electrode assembly to a midpoint of the first bend of the second electrode plate 202 is considered as a first fold of the second electrode plate and defined as a start layer of the second electrode plate 202; and, along the winding direction, a section from the midpoint of the first bend to the midpoint of the second bend is considered as a second fold of the second electrode plate and defined as a second layer of the second electrode plate. In other words, each bend formed by the second electrode plate 202 makes the total number of layers of the second electrode plate 202 increase by 1. For other layers, the arrangement is deduced similarly.
With respect to the plurality of first tabs 204, as shown in
In some embodiments, at least one first tab 204 is connected to each layer among the layers of the first electrode plate 201 other than the first inner layers and the first outer layers. Understandably, when the number of the first tabs 204 is one, the one first tab 204 may be disposed on any layer of the first electrode plate 201 other than the first inner layers and the first outer layers. When the number of the first tabs 204 is two or more, the arrangement of the two or more first tabs 204 on the first electrode plate 201 may be a continuous arrangement or a discrete arrangement, without being particularly limited herein.
In some embodiments, the number of first tabs 204 connected to each layer among the layers of the first electrode plate 201 other than the first inner layers and the first outer layers is not greater than 5. For example, the number of first tabs 204 connected to each layer may be 1, 2, 3, 4, or 5.
With respect to the plurality of second tabs 205, as shown in
In some embodiments, at least one second tab 205 is connected to each layer among the layers of the second electrode plate 202 other than the second inner layers and the second outer layers. Understandably, when the number of the second tabs 205 is one, the one second tab 205 may be disposed on any layer of the second electrode plate 202 other than the second inner layers and the second outer layers. When the number of the second tabs 205 is two or more, the arrangement of the two or more second tabs 205 on the second electrode plate 202 may be a continuous arrangement or a discrete arrangement, without being particularly limited herein.
In some embodiments, the number of second tabs 205 connected to each layer among the layers of the second electrode plate 202 other than the second inner layers and the second outer layers is not greater than 5. For example, the number of second tabs 205 connected to each layer may be 1, 2, 3, 4, or 5.
In addition, in order to facilitate readers to understand the technical effects brought by this technical solution, a comparative test is performed for some embodiments of this application, and a test of lithium plating of the negative electrode is described as an example. In the embodiments and comparative embodiments of this application, the lithium-ion battery is prepared by packaging an electrode assembly in an aluminum laminated film housing, and then injecting an electrolyte solution and sealing the housing, but the embodiments of this application are not limited to the example. The test process is as follows:
The electrode assembly is formed by winding a positive electrode plate, a negative electrode plate, and a separator. After being wound, both the number of layers of the positive electrode plate and the number of layers of the negative electrode plate are 28. That is, A=28, and B=28. Therefore, 3≤N≤16, 1≤M≤16, 3≤K≤16, and 1≤L≤16. It is assumed that N=3, M=1, K=3, and L=1. The positive tab is disposed on the 2nd to 26th layers, the number of positive tabs on each layer is 1, the negative tab is disposed on the 2nd to 28th layers, the number of negative tabs on each layer is 1, and the ambient temperature is 25° C. The battery is charged and then stands for 5 minutes, where the charging process is: 6 C 4.2 V, 5 C 4.32 V, and 3 C 4.5 V. Subsequently, the battery is discharged and then stands for 5 minutes, where the discharging process is to discharge the battery at a current of 0.7 C until the voltage reaches 3.0 V. Finally, the lithium plating status of the negative electrode is evaluated after the battery is fully charged and disassembled at the end of 300, 500, 700, 900, and 1100 cycles separately.
The electrode assembly is formed by winding a positive electrode plate, a negative electrode plate, and a separator. After being wound, both the number of layers of the positive electrode plate and the number of layers of the negative electrode plate are 28. That is, A=28, and B=28. Therefore, 3≤N≤16, 1≤M≤16, 3≤K≤16, and 1≤L≤16. It is assumed that N=3, M=1, K=3, and L=1. The positive tab is disposed on the 4th to 28th layers, the number of positive tabs on each layer is 1, the negative tab is disposed on the 4th to 28th layers, the number of negative tabs on each layer is 1, and the ambient temperature is 25° C. The battery is charged and then stands for 5 minutes, where the charging process is: 6 C 4.2 V, 5 C 4.32 V, and 3 C 4.5 V. Subsequently, the battery is discharged and then stands for 5 minutes, where the discharging process is to discharge the battery at a current of 0.7 C until the voltage reaches 3.0 V. Finally, the lithium plating status of the negative electrode is evaluated after the battery is fully charged and disassembled at the end of 300, 500, 700, 900, and 1100 cycles separately.
The electrode assembly is formed by winding a positive electrode plate, a negative electrode plate, and a separator. After being wound, both the number of layers of the positive electrode plate and the number of layers of the negative electrode plate are 28. That is, A=28, and B=28. Therefore, 3≤N≤16, 1≤M≤16, 3≤K≤16, and 1≤L≤16. It is assumed that N=3, M=1, K=3, and L=1. The positive tab is disposed on the 2nd to 24th layers, the number of positive tabs on each layer is 1, the negative tab is disposed on the 2nd to 24th layers, the number of negative tabs on each layer is 1, and the ambient temperature is 25° C. The battery is charged and then stands for 5 minutes, where the charging process is: 6 C 4.2 V, 5 C 4.32 V, and 3 C 4.5 V. Subsequently, the battery is discharged and then stands for 5 minutes, where the discharging process is to discharge the battery at a current of 0.7 C until the voltage reaches 3.0 V. Finally, the lithium plating status of the negative electrode is evaluated after the battery is fully charged and disassembled at the end of 300, 500, 700, 900, and 1100 cycles separately.
The electrode assembly is formed by winding a positive electrode plate, a negative electrode plate, and a separator. After being wound, both the number of layers of the positive electrode plate and the number of layers of the negative electrode plate are 28. That is, A=28, and B=28. Therefore, 3≤N≤16, 1≤M≤16, 3≤K≤16, and 1≤L≤16. It is assumed that N=3, M=1, K=3, and L=1. The positive tab is disposed on the 2nd to 9th layers, the number of positive tabs on each layer is 1, the negative tab is disposed on the 2nd to 9th layers, the number of negative tabs on each layer is 1, and the ambient temperature is 25° C. The battery is charged and then stands for 5 minutes, where the charging process is: 6 C 4.2 V, 5 C 4.32 V, and 3 C 4.5 V.
Subsequently, the battery is discharged and then stands for 5 minutes, where the discharging process is to discharge the battery at a current of 0.7 C until the voltage reaches 3.0 V. Finally, the lithium plating status of the negative electrode is evaluated after the battery is fully charged and disassembled at the end of 300, 500, 700, 900, and 1100 cycles separately.
The electrode assembly is formed by winding a positive electrode plate, a negative electrode plate, and a separator. After being wound, both the number of layers of the positive electrode plate and the number of layers of the negative electrode plate are 28. That is, A=28, and B=28. Therefore, 3≤N≤16, 1≤M≤16, 3≤K≤16, and 1≤L≤16. It is assumed that N=3, M=1, K=3, and L=1. The positive tab is disposed on the 21st to 28th layers, the number of positive tabs on each layer is 1, the negative tab is disposed on the 21st to 28th layers, the number of negative tabs on each layer is 1, and the ambient temperature is 25° C. The battery is charged and then stands for 5 minutes, where the charging process is: 6 C 4.2 V, 5 C 4.32 V, and 3 C 4.5 V. Subsequently, the battery is discharged and then stands for 5 minutes, where the discharging process is to discharge the battery at a current of 0.7 C until the voltage reaches 3.0 V. Finally, the lithium plating status of the negative electrode is evaluated after the battery is fully charged and disassembled at the end of 300, 500, 700, 900, and 1100 cycles separately.
The electrode assembly is formed by winding a positive electrode plate, a negative electrode plate, and a separator. After being wound, both the number of layers of the positive electrode plate and the number of layers of the negative electrode plate are 28. That is, A=28, and B=28. Therefore, 3≤N≤16, 1≤M≤16, 3≤K≤16, and 1≤L≤16. It is assumed that N=3, M=1, K=3, and L=1. The positive tab is disposed on the 10th to 18th layers, the number of positive tabs on each layer is 1, the negative tab is disposed on the 10th to 18th layers, the number of negative tabs on each layer is 1, and the ambient temperature is 25° C. The battery is charged and then stands for 5 minutes, where the charging process is: 6 C 4.2 V, 5 C 4.32 V, and 3 C 4.5 V. Subsequently, the battery is discharged and then stands for 5 minutes, where the discharging process is to discharge the battery at a current of 0.7 C until the voltage reaches 3.0 V. Finally, the lithium plating status of the negative electrode is evaluated after the battery is fully charged and disassembled at the end of 300, 500, 700, 900, and 1100 cycles separately.
The electrode assembly is formed by winding a positive electrode plate, a negative electrode plate, and a separator. After being wound, both the number of layers of the positive electrode plate and the number of layers of the negative electrode plate are 28. That is, A=28, and B=28. Therefore, 3≤N≤16, 1≤M≤16, 3≤K≤16, and 1≤L≤16. It is assumed that N=3, M=1, K=3, and L=1. The positive tab is disposed on the 10th to 18th layers, the number of positive tabs on each layer is 3, the negative tab is disposed on the 10th to 18th layers, the number of negative tabs on each layer is 3, and the ambient temperature is 25° C. The battery is charged and then stands for 5 minutes, where the charging process is: 6 C 4.2 V, 5 C 4.32 V, and 3 C 4.5 V. Subsequently, the battery is discharged and then stands for 5 minutes, where the discharging process is to discharge the battery at a current of 0.7 C until the voltage reaches 3.0 V. Finally, the lithium plating status of the negative electrode is evaluated after the battery is fully charged and disassembled at the end of 300, 500, 700, 900, and 1100 cycles separately.
The electrode assembly is formed by winding a positive electrode plate, a negative electrode plate, and a separator. After being wound, both the number of layers of the positive electrode plate and the number of layers of the negative electrode plate are 28. That is, A=28, and B=28. Therefore, 3≤N≤16, 1≤M≤16, 3≤K≤16, and 1≤L≤16. It is assumed that N=3, M=1, K=3, and L=1. The positive tab is disposed on the 6th to 22nd layers, the number of positive tabs on each layer is 1, the negative tab is disposed on the 6th to 22nd layers, the number of negative tabs on each layer is 1, and the ambient temperature is 25° C. The battery is charged and then stands for 5 minutes, where the charging process is: 6 C 4.2 V, 5 C 4.32 V, and 3 C 4.5 V. Subsequently, the battery is discharged and then stands for 5 minutes, where the discharging process is to discharge the battery at a current of 0.7 C until the voltage reaches 3.0 V. Finally, the lithium plating status of the negative electrode is evaluated after the battery is fully charged and disassembled at the end of 300, 500, 700, 900, and 1100 cycles separately.
The electrode assembly is formed by winding a positive electrode plate, a negative electrode plate, and a separator. After being wound, both the number of layers of the positive electrode plate and the number of layers of the negative electrode plate are 28. That is, A=28, and B=28. Therefore, 3≤N≤16, 1≤M≤16, 3≤K≤16, and 1≤L≤16. It is assumed that N=3, M=1, K=3, and L=1. The positive tab is disposed on the 6th to 22nd layers, the number of positive tabs on each layer is 1, the negative tab is disposed on the 10th to 18th layers, the number of negative tabs on each layer is 1, and the ambient temperature is 25° C. The battery is charged and then stands for 5 minutes, where the charging process is: 6 C 4.2 V, 5 C 4.32 V, and 3 C 4.5 V. Subsequently, the battery is discharged and then stands for 5 minutes, where the discharging process is to discharge the battery at a current of 0.7 C until the voltage reaches 3.0 V. Finally, the lithium plating status of the negative electrode is evaluated after the battery is fully charged and disassembled at the end of 300, 500, 700, 900, and 1100 cycles separately.
The electrode assembly is formed by winding a positive electrode plate, a negative electrode plate, and a separator. After being wound, both the number of layers of the positive electrode plate and the number of layers of the negative electrode plate are 28. That is, A=28, and B=28. Therefore, 3≤N≤16, 1≤M≤16, 3≤K≤16, and 1≤L≤16. It is assumed that N=3, M=1, K=3, and L=1. The positive tab is disposed on the 10th to 18th layers, the number of positive tabs on each layer is 1, the negative tab is disposed on the 6th to 22nd layers, the number of negative tabs on each layer is 1, and the ambient temperature is 25° C. The battery is charged and then stands for 5 minutes, where the charging process is: 6 C 4.2 V, 5 C 4.32 V, and 3 C 4.5 V. Subsequently, the battery is discharged and then stands for 5 minutes, where the discharging process is to discharge the battery at a current of 0.7 C until the voltage reaches 3.0 V. Finally, the lithium plating status of the negative electrode is evaluated after the battery is fully charged and disassembled at the end of 300, 500, 700, 900, and 1100 cycles separately.
The electrode assembly is formed by winding a positive electrode plate, a negative electrode plate, and a separator. After being wound, both the number of layers of the positive electrode plate and the number of layers of the negative electrode plate are 28. That is, A=28, and B=28. Therefore, 3≤N≤16, 1≤M≤16, 3≤K≤16, and 1≤L≤16. It is assumed that N=3, M=1, K=3, and L=1. The positive tab is disposed on the 10th to 17th layers, the number of positive tabs on each layer is 1, the negative tab is disposed on the 10th to 17th layers, the number of negative tabs on each layer is 1, and the ambient temperature is 25° C. The battery is charged and then stands for 5 minutes, where the charging process is: 6 C 4.2 V, 5 C 4.32 V, and 3 C 4.5 V. Subsequently, the battery is discharged and then stands for 5 minutes, where the discharging process is to discharge the battery at a current of 0.7 C until the voltage reaches 3.0 V. Finally, the lithium plating status of the negative electrode is evaluated after the battery is fully charged and disassembled at the end of 300, 500, 700, 900, and 1100 cycles separately.
The electrode assembly is formed by winding a positive electrode plate, a negative electrode plate, and a separator. After being wound, both the number of layers of the positive electrode plate and the number of layers of the negative electrode plate are 28. That is, A=28, and B=28. Therefore, 3≤N≤16, 1≤M≤16, 3≤K≤16, and 1≤L≤16. It is assumed that N=3, M=1, K=3, and L=1. The positive tab is disposed on the 14th to 21st layers, the number of positive tabs on each layer is 1, the negative tab is disposed on the 14th to 21st layers, the number of negative tabs on each layer is 1, and the ambient temperature is 25° C. The battery is charged and then stands for 5 minutes, where the charging process is: 6 C 4.2 V, 5 C 4.32 V, and 3 C 4.5 V. Subsequently, the battery is discharged and then stands for 5 minutes, where the discharging process is to discharge the battery at a current of 0.7 C until the voltage reaches 3.0 V. Finally, the lithium plating status of the negative electrode is evaluated after the battery is fully charged and disassembled at the end of 300, 500, 700, 900, and 1100 cycles separately.
The electrode assembly is formed by winding a positive electrode plate, a negative electrode plate, and a separator. After being wound, both the number of layers of the positive electrode plate and the number of layers of the negative electrode plate are 28. That is, A=28, and B=28. Therefore, 3≤N≤16, 1≤M≤16, 3≤K≤16, and 1≤L≤16. It is assumed that N=3, M=1, K=3, and L=1. The positive tab is disposed on the 4th to 27th layers, the number of positive tabs on each layer is 1, the negative tab is disposed on the 4th to 27th layers, the number of negative tabs on each layer is 1, and the ambient temperature is 25° C. The battery is charged and then stands for 5 minutes, where the charging process is: 6 C 4.2 V, 5 C 4.32 V, and 3 C 4.5 V.
Subsequently, the battery is discharged and then stands for 5 minutes, where the discharging process is to discharge the battery at a current of 0.7 C until the voltage reaches 3.0 V. Finally, the lithium plating status of the negative electrode is evaluated after the battery is fully charged and disassembled at the end of 300, 500, 700, 900, and 1100 cycles separately.
The electrode assembly is formed by winding a positive electrode plate, a negative electrode plate, and a separator. After being wound, both the number of layers of the positive electrode plate and the number of layers of the negative electrode plate are 28. That is, A=28, and B=28. Therefore, 3≤N≤16, 1≤M≤16, 3≤K≤16, and 1≤L≤16. It is assumed that N=3, M=1, K=3, and L=1. The positive tab is disposed on the 4th to 27th layers, the number of positive tabs on each layer is 1, the negative tab is disposed on the 10th to 18th layers, the number of negative tabs on each layer is 1, and the ambient temperature is 25° C. The battery is charged and then stands for 5 minutes, where the charging process is: 6 C 4.2 V, 5 C 4.32 V, and 3 C 4.5 V. Subsequently, the battery is discharged and then stands for 5 minutes, where the discharging process is to discharge the battery at a current of 0.7 C until the voltage reaches 3.0 V. Finally, the lithium plating status of the negative electrode is evaluated after the battery is fully charged and disassembled at the end of 300, 500, 700, 900, and 1100 cycles separately.
The test results are shown in the following table:
As can be seen from the test data in the table, in Comparative Embodiments 1 to 5, when the battery has been charged and discharged for 500 or 700 cycles, slight lithium plating occurs. However, in Embodiments 1 to 9, when the battery has been charged and discharged for 500 or 700 cycles, no lithium plating occurs, indicating that Embodiments 1 to 9 are favorable for alleviating lithium plating in contrast to Comparative Embodiments 1 to 5 when the battery has been charged and discharged for 500 to 700 cycles. In Comparative Embodiments 1 to 5, when the battery has been charged and discharged for 900 cycles, slight lithium plating or a medium level of lithium plating occurs. In Embodiments 1, 2, and 7, when the battery has been charged and discharged for 900 cycles, no lithium plating occurs, indicating that the technical solutions of such embodiments can alleviate lithium plating when the battery has been charged and discharged for 900 cycles.
In some embodiments of this application, an electrode assembly and a plurality of first tabs are disposed. The electrode assembly includes a first electrode plate, a second electrode plate, and a separator. The separator is disposed between the first electrode plate and the second electrode plate. The first electrode plate, the separator, and the second electrode plate are stacked and wound. In addition, One end of the plurality of first tabs is connected to a region of the first electrode plate other than first inner layers and first outer layers. The first inner layers include N layers starting from a start layer of the first electrode plate along a direction from the start layer to an end layer of the first electrode plate; and the first outer layers include M layers starting from the end layer of the first electrode plate along a direction from the end layer to the start layer of the first electrode plate, where M≥1, and N≥3. By setting the distribution positions of the plurality of first tabs, the electromotive force at the first inner layers and the first outer layers of the first electrode plate is reduced during charging and discharging of the electrochemical device, and the speed of lithiation at a local region is reduced, thereby alleviating lithium plating of the battery.
This application further provides an embodiment of a battery module. The battery module includes the electrochemical device disclosed above. The functionality and structure of the electrochemical device may be learned by referring to the above embodiments, the details of which are omitted herein.
This application further provides an embodiment of an electrical device. The electrical device includes the battery module disclosed above. The functionality and structure of the battery module may be learned by referring to the above embodiment, the details of which are omitted herein.
What is described above is merely some embodiments of this application, and does not limit the patent scope of this application in any way. All equivalent structural variations and equivalent process variations made by using the content of the specification and the drawings of this application, and the content hereof used directly or indirectly in other related technical fields, still fall within the patent protection scope of this application.
This application is a continuation under 35 U.S.C. § 120 of international patent application PCT/CN2021/140514 filed on Dec. 22, 2021, the entire content of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/CN2021/140514 | Dec 2021 | WO |
| Child | 18750296 | US |
