Electrochemical device and electronic equipment

Abstract

The application provides an electrochemical device and an electronic device. The electrochemical device has a length direction, a width direction and a thickness direction, and comprises a negative electrode tab, a negative electrode tab, a lithium supplement tab, a lithium supplement tab and a first diaphragm. The negative electrode tab is connected to one side of the negative electrode tab in the thickness direction; the lithium supplement tab comprises a lithium supplement current collector and a first lithium layer, the lithium supplement current collector is stacked on the negative electrode tab in the thickness direction, and the first lithium layer is distributed on at least one side of the lithium supplement current collector in the thickness direction; the lithium supplement tab is connected to the lithium supplement current collector; the first diaphragm is arranged between the lithium supplement tab and the negative electrode tab; the electrochemical device has a projection plane perpendicular to the thickness direction, the first lithium layer has a first projection in the projection plane, the negative electrode tab has a second projection in the projection plane, and the first projection avoids the second projection. The electronic device has the electrochemical device. The electrochemical device and the electronic device have higher safety.

Description

Technical Field

[0001] This application relates to the field of electrochemical energy storage, specifically to electrochemical devices and electronic equipment. Background Technology

[0002] Lithium-ion battery cells replenish lithium to the negative electrode using a lithium-ion replenishing electrode. However, existing lithium-ion replenishing electrodes are prone to lithium plating near the tabs of the negative electrode during the replenishment process, which can affect the safety of the battery cell. Utility Model Content

[0003] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes an electrochemical device that can reduce lithium plating and improve safety.

[0004] This application also proposes an electronic device having the above-mentioned electrochemical device.

[0005] An electrochemical device according to a first aspect embodiment of this application has a length direction, a width direction, and a thickness direction, including: Negative electrode sheet; A negative electrode tab is connected to one side of the negative electrode sheet in the thickness direction; A lithium-filling electrode includes a lithium-filling current collector and a first lithium layer, wherein the lithium-filling current collector is stacked on the negative electrode in the thickness direction, and the first lithium layer is distributed at least on at least one side of the lithium-filling current collector in the thickness direction; A lithium replenishment tab is connected to the lithium replenishment current collector; A first separator is disposed between the lithium-filling electrode and the negative electrode; The electrochemical device has a projection plane perpendicular to the thickness direction, the first lithium layer has a first projection on the projection plane, the negative electrode tab has a second projection on the projection plane, and the first projection avoids the second projection.

[0006] The electrochemical device according to the embodiments of this application has at least the following beneficial effects: The electrochemical device of this application has a first clearance groove on the first lithium layer of the lithium replenishing electrode, and the projection of the first clearance groove accommodates the projection of the negative electrode connection. Therefore, the portion of the first lithium layer near the negative electrode connection has a lower lithium content. When the lithium replenishing electrode is used to replenish lithium to the negative electrode, less lithium migrates to the negative electrode from the portion of the first lithium layer near the negative electrode connection. The lithium replenishment rate of the portion of the negative electrode near the negative electrode connection is lower, and the lithium content after replenishment is lower. Therefore, the portion of the negative electrode near the negative electrode connection is less likely to produce lithium plating, and the overall safety of the electrochemical device is stronger.

[0007] According to some embodiments of this application, the electrochemical device further includes a positive electrode and a positive electrode tab, the positive electrode tab being connected to the positive electrode; the positive electrode and the negative electrode are wound together around an axis parallel to the length direction to form a winding structure; the winding structure includes a straight region and a bent region arranged along the width direction, and the negative electrode includes a plurality of first straight portions located in the straight region; The lithium-replenishing electrode is stacked on the first flat portion, and the first separator is located between the first flat portion and the lithium-replenishing electrode.

[0008] According to some embodiments of this application, the lithium supplement electrode is located on the outside of the wound structure.

[0009] According to some embodiments of this application, the electrochemical device further includes a second diaphragm disposed between the positive electrode and the negative electrode to separate the positive electrode and the negative electrode; The positive electrode also includes a plurality of second flat portions located in the flat region, and in the thickness direction, the lithium supplement electrode is located on the side of the second separator close to the first flat portion.

[0010] According to some embodiments of this application, the electrochemical device includes a plurality of negative electrode plates, a plurality of positive electrode plates, a plurality of positive electrode tabs, and a plurality of third membranes, wherein each positive electrode plate is connected to at least one positive electrode tab; along the thickness direction, the negative electrode plates and the positive electrode plates are stacked alternately, and the third membranes are provided between adjacent negative electrode plates and positive electrode plates.

[0011] According to some embodiments of this application, the lithium supplement electrode is located on one side of all the negative electrode electrodes in the thickness direction.

[0012] According to some embodiments of this application, the lithium-filling electrode is located on the side of the third separator closer to the negative electrode.

[0013] According to some embodiments of this application, the lithium replenishing tab is integrally connected to the lithium replenishing current collector.

[0014] According to some embodiments of this application, the electrochemical device includes a plurality of lithium replenishing tabs, all of which are connected to the lithium replenishing current collector.

[0015] An electronic device according to a second aspect of this application is characterized in that it includes an electrochemical device as described in any of the above embodiments.

[0016] The electronic device according to the embodiments of this application has at least the following beneficial effects: The electronic device of this application has a first clearance groove on the first lithium layer of the lithium replenishing electrode, and the projection of the first clearance groove accommodates the projection of the negative electrode connection. Therefore, the portion of the first lithium layer near the negative electrode connection has a lower lithium content. When the negative electrode is replenished with lithium using the lithium replenishing electrode, less lithium migrates to the negative electrode from the portion of the first lithium layer near the negative electrode connection. The lithium replenishment rate of the portion of the negative electrode near the negative electrode connection is lower, and the lithium content after replenishment is lower. Therefore, the portion of the negative electrode near the negative electrode connection is less likely to produce lithium plating, and the overall safety of the electronic device is also stronger.

[0017] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0018] The present application will be further described below with reference to the accompanying drawings and embodiments, wherein: Figure 1 This is a schematic diagram of some embodiments of the first aspect of this application; Figure 2 for Figure 1 A cross-sectional view shown at point AA; Figure 3 This is a cross-sectional schematic diagram of some embodiments of the second aspect of this application; Figure 4 This is a schematic diagram of some embodiments of the third aspect of this application; Figure 5 for Figure 4 A cross-sectional view shown at point BB; Figure 6 This is a schematic diagram of some embodiments of the fourth aspect of this application; Figure 7 This is a schematic diagram of the structure of the lithium electrode sheet connected to the lithium electrode tab in some embodiments of the fifth aspect of this application; Figure 8 for Figure 7 A cross-sectional view shown at point CC; Figure 9 This is a cross-sectional schematic diagram of a lithium electrode sheet according to some embodiments of the sixth aspect of this application.

[0019] Figure label: Electrochemical device 10; Negative electrode plate 100, first straight section 110; Negative electrode tab 200, negative electrode connection part 210, negative electrode extension part 220; Lithium-replenishing electrode 300, lithium-replenishing current collector 310, first lithium layer 320, first clearance groove 321, second lithium layer 330, second clearance groove 331; Lithium-ion electrode 400; First diaphragm 500; Positive electrode plate 600, second straight section 610; Positive electrode tab 700; Winding structure 800, straight section 810, bending section 820; Second diaphragm 900; Third diaphragm 1000. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. The embodiments of this application may omit unnecessary detailed descriptions. For example, detailed descriptions of well-known matters and repeated descriptions of actually identical structures may be omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art.

[0021] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0022] As used herein, the terms “approximately,” “generally,” “substantially,” and “about” are used to describe and indicate small variations. When used in conjunction with an event or situation, the terms may refer to examples in which the event or situation occurred precisely and examples in which the event or situation occurred very approximately. For example, when used in conjunction with numerical values, the terms may refer to a range of variation less than or equal to ±10% of the numerical value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%. For example, if the difference between two values ​​is less than or equal to ±10% of the average of the values ​​(e.g., less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%), then the two values ​​can be considered "substantially" the same.

[0023] Furthermore, for ease of description, "first," "second," "third," etc., can be used in this article to distinguish different components of a figure or a series of figures. "First," "second," "third," etc., are not intended to describe the corresponding components.

[0024] Additionally, quantities, ratios, and other numerical values ​​are sometimes presented in range format in this document. It should be understood that such range format is for convenience and brevity and should be interpreted flexibly to include not only the numerical values ​​explicitly specified as range limits, but also all individual numerical values ​​or subranges covered within the range, as if each numerical value and subrange were explicitly specified.

[0025] In the detailed description and claims, a list of items connected by the terms "one of," "among," "a kind of," or other similar terms may mean any of the listed items. For example, if items A and B are listed, then the phrase "one of A and B" means only A or only B. In another example, if items A, B, and C are listed, then the phrase "one of A, B, and C" means only A; only B; or only C. Item A may contain a single element or multiple elements. Item B may contain a single element or multiple elements. Item C may contain a single element or multiple elements. In the detailed description and claims, a list of items connected by the term "at least one of" may mean any combination of the listed items. For example, if items A and B are listed, then the phrase "at least one of A and B" means only A; only B; or A and B. In another instance, if items A, B, and C are listed, then the phrase "at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C.

[0026] In the following description, all figures disclosed in this application are approximate values, regardless of whether the terms "about" or "approximately" are used in conjunction. They may vary by 1%, 2%, 5%, or sometimes 10% to 20%. Whenever a range of values ​​with a lower limit (RL) and an upper limit (RU) is disclosed, any values ​​falling within that range are specifically disclosed. Specifically, the following values ​​within this range are specifically disclosed: R = RL + k * (RU - RL), where k is a variable with a 1% increment from 1% to 100%, i.e., k is 1%, 2%, 3%, 4%, 5%, ..., 50%, 51%, 52%, ..., 95%, 96%, 97%, 98%, 99%, or 100%. Furthermore, any range of values ​​defined by the two R values ​​as defined above are also specifically disclosed.

[0027] Throughout this specification, references to "implementation," "partial implementation," "one implementation," "another implementation," "specific method," or "partial method" mean that at least one implementation or embodiment in this application includes the specific features, structures, materials, or characteristics described in that implementation or embodiment.

[0028] In this application, numerical ranges are involved. Unless otherwise specified, the numerical ranges mentioned above are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Any lower limit can be combined with any upper limit to form a range not explicitly stated; and any lower limit can be combined with other lower limits to form a range not explicitly stated, just as any upper limit can be combined with any other upper limit to form a range not explicitly stated. Furthermore, each individually disclosed point or single value can itself serve as a lower or upper limit and be combined with any other point or single value or with other lower or upper limits to form a range not explicitly stated.

[0029] Please refer to Figures 1 to 9 As shown, this application proposes an electrochemical device 10, which has a length direction, a width direction and a thickness direction, and includes a negative electrode 100, a negative electrode tab 200, a lithium supplement electrode 300, a lithium supplement tab 400 and a first separator 500.

[0030] Please refer to Figure 1 , Figure 2 As shown, the negative electrode tab 200 includes a negative electrode connection portion 210 and a negative electrode extension portion 220 connected to each other. The negative electrode connection portion 210 is connected to the negative electrode plate 100. The negative electrode extension portion 220 can output the electrical energy stored on the negative electrode plate 100 through the connection between the negative electrode connection portion 210 and the negative electrode plate 100.

[0031] Please refer to Figure 2 , Figure 7 As shown, where Figure 7 It shows Figure 2 The structure of the lithium-filled electrode 300 and its relative position to the negative electrode tab 200 are described. The lithium-filled electrode 300 is stacked on top of the negative electrode 100 in the thickness direction, and includes a lithium-filled current collector 310 and a first lithium layer 320 stacked together. The lithium-filled tab 400 is connected to the lithium-filled current collector 310; the negative electrode tab 200 is electrically connected to the lithium-filled tab 400 so that the first lithium layer 320 can replenish lithium to the negative electrode 100. A first separator 500 is disposed between the lithium-filled electrode 300 and the negative electrode 100. The first separator 500 disposed between the lithium-filled electrode 300 and the negative electrode 100 can isolate the lithium-filled electrode 300 and the negative electrode 100, avoiding short circuits caused by direct contact between the lithium-filled electrode 300 and the negative electrode 100. When the lithium supplement tab 400 is connected to the negative electrode tab 200, the lithium in the first lithium layer 320 can be converted into lithium ions and migrate toward the negative electrode active material layer of the negative electrode 100, increasing the lithium content of the negative electrode 100.

[0032] Please refer to Figure 7 , Figure 8 As shown, where Figure 7The structure of the lithium replenishing electrode 300 in the electrochemical device 10 and its relative position to the negative electrode tab 200 are shown. The lithium replenishing electrode 300 has a first clearance groove 321 on the first lithium layer 320. The first clearance groove 321 is recessed relative to the surface of the first lithium layer 320 away from the lithium replenishing current collector 310. The electrochemical device 10 has a projection plane perpendicular to the thickness direction. The first clearance groove 321 has a first projection on the projection plane, and the negative electrode connection portion 210 has a second projection on the projection plane. The first projection accommodates the second projection.

[0033] Through long-term practice, the inventors discovered that because the current density of the negative electrode tab 200 is high during charging, the lithium ion deposition rate of the negative electrode plate 100 near the negative electrode tab 200 is high, resulting in a higher lithium content in the portion of the negative electrode plate 100 near the negative electrode connection 210. In this application, a first clearance groove 321 is provided on the first lithium layer 320 of the lithium replenishing electrode 300, and the projection of the first clearance groove 321 accommodates the projection of the negative electrode connection portion 210. Therefore, the portion of the first lithium layer 320 near the negative electrode connection portion 210 has a lower lithium content. When the lithium replenishing electrode 300 is used to replenish lithium to the negative electrode 100, less lithium migrates from the portion of the first lithium layer 320 near the negative electrode connection portion 210 to the negative electrode 100. The lithium replenishment rate of the portion of the negative electrode 100 near the negative electrode connection portion 210 is lower, and the lithium content after lithium replenishment is lower. Therefore, the portion of the negative electrode 100 near the negative electrode connection portion 210 is less likely to produce lithium plating, and the overall safety of the electrochemical device 10 is stronger.

[0034] Without departing from the inventive concept of this application, those skilled in the art can adjust the contour of the first clearance groove 321. For example, please refer to... Figure 7 , Figure 8 As shown, where Figure 7 The structure of the lithium replenishing electrode 300 in the electrochemical device 10 and its relative position to the negative electrode tab 200 are shown. The first clearance groove 321 is provided on the side of the negative electrode tab 200 in the length direction and extends in the width direction. The side of the first clearance groove 321 away from the negative electrode tab 200 in the length direction extends beyond the negative electrode connection portion 210, so that the first projection accommodates the second projection. Less lithium migrates from the part of the first lithium layer 320 near the negative electrode connection portion 210 to the negative electrode electrode 100, and the overall safety of the electrochemical device 10 is stronger.

[0035] Those skilled in the art can further improve the structure of the lithium-filled electrode 300.

[0036] For example, please refer to Figure 9As shown, in some embodiments, the lithium replenishing electrode 300 further includes a second lithium layer 330, with the first lithium layer 320 and the second lithium layer 330 respectively stacked on both sides of the lithium replenishing current collector 310 in the thickness direction. The lithium replenishing electrode 300 has a second clearance groove 331 in the second lithium layer 330. The second clearance groove 331 is recessed relative to the surface of the second lithium layer 330 away from the surface of the lithium replenishing current collector 310, and the second clearance groove 331 has a third projection in the projection plane, the third projection accommodating the second projection.

[0037] Through the above scheme, the portion of the second lithium layer 330 near the negative electrode connection 210 has a lower lithium content. When the negative electrode 100 is replenished with lithium using the replenishing electrode 300, less lithium migrates from the portion of the second lithium layer 330 near the negative electrode connection 210 to the negative electrode 100. The replenishment rate of the portion of the negative electrode 100 near the negative electrode connection 210 is lower, resulting in a lower lithium content after replenishment. Therefore, the portion of the negative electrode 100 near the negative electrode connection 210 is less prone to lithium plating, thus enhancing the overall safety of the electrochemical device 10. On the other hand, the portion of the second lithium layer 330 away from the negative electrode connection 210 can provide more lithium to the portion of the negative electrode 100 away from the negative electrode connection 210, thereby improving the lithium-ion cycle performance.

[0038] Further, please refer to Figure 9 As shown, in some embodiments, the first clearance groove 321 is recessed into the surface of the lithium current collector 310. The above solution can further reduce the amount of lithium migrating from the portion of the first lithium layer 320 near the negative electrode connection 210 to the negative electrode sheet 100, thus enhancing the overall safety of the electrochemical device 10.

[0039] Please refer to Figure 9 As shown, in some embodiments, the second clearance groove 331 is recessed into the surface of the lithium current collector 310. The above solution can further reduce the migration of lithium from the portion of the second lithium layer 330 near the negative electrode connection 210 to the negative electrode sheet 100, thus enhancing the overall safety of the electrochemical device 10.

[0040] In some embodiments, the lithium replenishing tab 400 and the lithium replenishing current collector 310 are integrally connected. Through the above solution, the lithium replenishing tab 400 and the lithium replenishing current collector 310 can become an integral structure, resulting in stronger mechanical stability.

[0041] In some embodiments, the electrochemical device 10 includes a plurality of lithium replenishing tabs 400, all of which are connected to the lithium replenishing current collector 310. Each of the plurality of lithium replenishing tabs 400 can be connected to the negative electrode tab 200. When the plurality of lithium replenishing tabs 400 are simultaneously connected to the negative electrode tab 200, the lithium replenishing electrode 300 can transmit current through the plurality of lithium replenishing tabs 400, resulting in a more uniform potential and current distribution on the lithium replenishing electrode 300. This facilitates higher lithium migration efficiency at various points on the first lithium layer 320 and improves the lithium replenishment efficiency for the portion of the negative electrode 100 far from the negative electrode connection portion 210.

[0042] This application does not limit the material of the lithium replenishing current collector 310. In some embodiments, the lithium replenishing current collector 310 is made of copper foil or stainless steel foil. In some embodiments, the lithium replenishing current collector 310 is a composite current collector. In some embodiments, the lithium replenishing current collector 210 is made of a mixture of polymer materials and conductive fillers, wherein the polymer materials include polyethylene, polypropylene, polytetrafluoroethylene, polyacrylamide, polyamide, polymethyl methacrylate, polyacrylonitrile, polyethylene oxide, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, and polyvinylpyrrolidone, etc., and the conductive fillers include non-metallic fillers such as carbon black, graphite, carbon fiber, and carbon nanotubes, as well as metallic fillers such as copper and aluminum, and metal oxide fillers such as copper oxide and zinc oxide.

[0043] In some embodiments, the electrochemical device 10 includes a positive electrode 600, a negative electrode 100, an electrolyte, and a separator, with the separator located between the positive electrode 600 and the negative electrode 100.

[0044] It should be noted that the electrochemical device 10 provided in this application includes any device in which an electrochemical reaction occurs to convert chemical energy into electrical energy and vice versa. Specific, non-limiting examples include all types of primary batteries, secondary batteries, fuel cells, solar cells, or capacitors. In particular, the electrochemical device 10 is a lithium secondary battery, including lithium metal secondary batteries, lithium-ion secondary batteries, lithium polymer secondary batteries, or lithium-ion polymer secondary batteries.

[0045] For example, please refer to Figure 1 , Figure 2 , Figure 3 , Figure 7 , Figure 8 As shown, where Figure 7 It shows Figure 2The structure of the supplementary lithium electrode 300 and its relative position to the negative electrode tab 200 are discussed. In some embodiments, the electrochemical device 10 further includes a positive electrode 600 and a positive electrode tab 700, with the positive electrode tab 700 connected to the positive electrode 600. The positive electrode 600 and the negative electrode 100 are wound together around an axis parallel to the length direction to form a winding structure 800. The winding structure 800 includes a straight region 810 and a bent region 820 arranged along the width direction. The negative electrode 100 includes a plurality of first straight portions 110 located in the straight regions 810. The supplementary lithium electrode 300 is stacked on the first straight portions 110, and a first separator 500 is located between the first straight portions 110 and the supplementary lithium electrode 300.

[0046] In the above embodiments, the positive electrode 600 and the negative electrode 100 can be directly formed into a wound structure 800 that can be assembled into a shell through a winding action, which is beneficial for automated production using existing winding machines and has higher production efficiency. The first lithium layer 320 can migrate to the negative electrode 100 during the lithium replenishment process to replenish the lithium on the negative electrode 100.

[0047] Without departing from the inventive concept of this application, those skilled in the art can further adjust the position of the lithium-filled electrode 300 in the thickness direction.

[0048] Please refer to Figure 2 As shown, in some embodiments, the lithium-replenishing electrode 300 is located outside the winding structure 800. When the lithium-replenishing electrode 300 is located outside the winding structure 800, the first separator 500 is also located outside the winding structure 800, such that the lithium-replenishing electrode 300 and the negative electrode 100 are separated by the first separator 500. With the above solution, when foreign matter on one side of the electrochemical device 10 in the thickness direction compresses the electrochemical device 10, the lithium-replenishing electrode 300 can reduce the compression of the winding structure 800 by the foreign matter, thus protecting the winding structure 800.

[0049] Please refer to Figure 3As shown, in some embodiments, the electrochemical device 10 further includes a second separator 900 disposed between the positive electrode 600 and the negative electrode 100 to separate them. The positive electrode 600 also includes a plurality of second straight portions 610 located in the straight region 810. In the thickness direction, the lithium-filled electrode 300 is located on the side of the second separator 900 near the first straight portion 110. With the above solution, the lithium-filled electrode 300 is separated from the negative electrode 100 by the first separator 500, and also separated from the positive electrode 600 by the second separator 900 disposed between the positive electrode 600 and the negative electrode 100, thereby preventing the lithium-filled electrode 300 from being short-circuited to either the negative electrode 100 or the positive electrode 600. Furthermore, since the lithium replenishing electrode 300 is disposed inside the winding structure 800, the rigidity of the lithium replenishing electrode 300 itself can further strengthen the structure of the winding structure 800, thereby improving the stability of the electrochemical device 10.

[0050] The electrochemical device 10 of this application can also be of other types. For example, please refer to... Figure 4 , Figure 5 , Figure 6 , Figure 7 , Figure 8 As shown, where Figure 7 It shows Figure 5 The structure of the intermediate lithium electrode 300 and its relative position to the negative electrode tab 200 are as follows: In some embodiments, the electrochemical device 10 includes a plurality of negative electrode plates 100, a plurality of positive electrode plates 600, a plurality of positive electrode tabs 700 and a plurality of third separators 1000, each positive electrode plate 600 being connected to at least one positive electrode tab 700; along the thickness direction, the negative electrode plates 100 and the positive electrode plates 600 are staggered and stacked, and a third separator 1000 is provided between adjacent negative electrode plates 100 and positive electrode plates 600.

[0051] Multiple negative electrode plates 100 and multiple positive electrode plates 600 are staggered along the thickness direction and separated by a third separator 1000, which enables the electrochemical device 10 to have a higher energy density. The first lithium layer 320 can migrate to the negative electrode plate 100 during lithium replenishment to replenish the lithium in the negative electrode plate 100.

[0052] Without departing from the inventive concept of this application, those skilled in the art can further adjust the position of the lithium-filled electrode 300 in the thickness direction.

[0053] Please refer to Figure 5As shown, in some embodiments, the lithium-supplementing electrode 300 is located on one side of all the negative electrode plates 100 in the thickness direction. With this arrangement, the lithium-supplementing electrode 300 is located on one side of all the negative electrode plates 100 in the thickness direction, and the first separator 500 is disposed between the closest negative electrode plate 100 and the lithium-supplementing electrode 300. When foreign matter on one side of the thickness direction compresses the electrochemical device 10, the lithium-supplementing electrode 300 can reduce the compression of the positive electrode plate 600 and the negative electrode plate 100 by the foreign matter, thus protecting the positive electrode plate 600 and the negative electrode plate 100.

[0054] Please refer to Figure 6 As shown, in some embodiments, the lithium-replenishing electrode 300 is located on the side of the third separator 1000 closer to the negative electrode 100. Through this arrangement, the lithium-replenishing electrode 300 is separated from the negative electrode 100 by the first separator 500, and further separated from the positive electrode 600 by the third separator 1000 disposed between the positive electrode 600 and the negative electrode 100, thereby preventing the lithium-replenishing electrode 300 from being short-circuited to either the negative electrode 100 or the positive electrode 600. Furthermore, since the lithium-replenishing electrode 300 is disposed between the positive electrode 600 and the negative electrode 100, the rigidity of the lithium-replenishing electrode 300's own structure can further reinforce the structure formed by the stacking of multiple positive electrode 600s and multiple negative electrode 100s, improving the stability of the electrochemical device 10.

[0055] In some embodiments, the negative electrode sheet may include a negative current collector and a negative active material layer disposed on at least one side of the negative current collector.

[0056] In some embodiments, the negative current collector is a metal foil or a composite current collector. In some embodiments, the metal foil is a copper foil. The composite current collector may include a metal foil substrate and a conductive layer disposed on at least one side of the metal foil substrate. In some embodiments, the negative electrode active material may include at least one of natural graphite particles, synthetic graphite particles, hard carbon, soft carbon, mesophase carbon microspheres (MCMB), Sn, SnO2, SnO, Li4Ti5O12 (LTO), Si materials, silicon-carbon (Si-C) composite materials, silicon-nitrogen (Si-N) composite materials, and silicon-oxygen (Si-O) composite materials. The negative electrode active material of this application is not limited to the above-mentioned materials, but also includes other materials that can be used as negative electrode active materials in batteries.

[0057] In some embodiments, the negative electrode binder may include at least one of polyacrylic acid, polymethacrylic acid, polyacrylate, polymethacrylate, polyacrylamide, styrene-butadiene rubber, acrylic styrene-butadiene rubber, acrylic acid-acrylonitrile-acrylamide copolymer, acrylic acid-acrylonitrile-acrylate copolymer, acrylonitrile-butadiene rubber, nitrile rubber, acrylonitrile-styrene-butadiene copolymer, acryloyl rubber, butyl rubber, fluororubber, polytetrafluoroethylene, polyvinyl alcohol, polyvinyl acetate, polyepoxychloropropane, polyphosphazene, polyacrylonitrile, polystyrene, latex, acrylic resin, phenolic resin, epoxy resin, carboxymethyl cellulose, hydroxypropyl cellulose, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl cellulose, carboxymethyl chitosan, polyester, polyamide, polyether, polyimide, polycarboxylic acid ester, polycarboxylic acid, polyurethane, alginate, fluorinated polymer, chlorinated polymer, polyvinylidene fluoride, and poly(vinylidene fluoride)-hexafluoropropylene. The negative electrode binder of this application is not limited to the above-mentioned materials, but also includes other materials that can be used as battery negative electrode binders.

[0058] In some embodiments, the negative electrode conductive agent may include at least one of carbon, carbon black, graphite, expanded graphite, graphene, graphene nanosheets, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon fibers, carbon nanofibers, graphitized carbon sheets, carbon nanotubes, carbon nanotubes, activated carbon, and mesoporous carbon. The negative electrode conductive agent of this application is not limited to the above-mentioned materials, but also includes other materials that can be used as battery negative electrode conductive agents.

[0059] In some embodiments, the positive electrode 600 may include a positive current collector and a positive active material layer disposed on at least one side of the positive current collector.

[0060] In some embodiments, the positive current collector is a metal foil or a composite current collector. In some embodiments, the metal foil is an aluminum foil. The composite current collector may include a metal foil substrate and a conductive layer disposed on at least one side of the metal foil substrate.

[0061] In some embodiments, the conductive layer may include at least one of carbon, carbon black, graphite, expanded graphite, graphene, graphene nanosheets, carbon fiber, carbon nanofiber, graphitized carbon sheet, carbon tube, carbon nanotube, activated carbon, and mesoporous carbon. In some embodiments, the positive electrode active material layer may include a positive electrode active material, a positive electrode binder, and a positive electrode conductive agent. In some embodiments, the positive electrode active material is selected from the group consisting of LiCoO2, LiNiO2, LiNixMnyO2, Li1+zNixMnyCo1-x-yO2, LiNixCoyAlzO2, LiV2O5, LiTiS2, LiMoS2, LiMnO2, LiCrO2, LiMn2O4, Li2MnO3, LiFeO2, LiFePO4, LiMnPO4, and combinations thereof, wherein each x is independently from 0.2 to 0.9; each y is independently from 0.1 to 0.45; and each z is independently from 0 to 0.2. The positive electrode active material of this application is not limited to the above-mentioned materials, but also includes other materials that can be used as positive electrode active materials. In some embodiments, the positive electrode active material is selected from the group consisting of LiCoO2, LiNiO2, LiNixMnyO2, Li1+zNixMnyCo1-x-yO2, LiNixCoyAlzO2, LiV2O5, LiTiS2, LiMoS2, LiMnO2, LiCrO2, LiMn2O4, LiFeO2, LiFePO4, and combinations thereof, wherein each x is independently 0.4 to 0.6; each y is independently 0.2 to 0.4; and each z is independently 0 to 0.1. In some embodiments, the positive electrode active material is Li1+xNiaMnbCocAl(1-abc)O2; wherein -0.2≤x≤0.2, 0≤a<1, 0≤b<1, 0≤c<1, and a+b+c≤1.

[0062] In some embodiments, the positive electrode active material has the general formula Li1+xNiaMnbCocAl(1-abc)O2, wherein 0.33≤a≤0.92, 0.33≤a≤0.9, 0.33≤a≤0.8, 0.5≤a≤0.92, 0.5≤a≤0.9, 0.5≤a≤0.8, 0.6≤a≤0.92, or 0.6≤a≤0.9. The following conditions apply: 0≤b≤0.5, 0≤b≤0.3, 0.1≤b≤0.5, 0.1≤b≤0.4, 0.1≤b≤0.3, 0.1≤b≤0.2, or 0.2≤b≤0.5; 0≤c≤0.5, 0≤c≤0.3, 0.1≤c≤0.5, 0.1≤c≤0.4, 0.1≤c≤0.3, 0.1≤c≤0.2, or 0.2≤c≤0.5. In some embodiments, the positive electrode active material is doped with a dopant selected from the group consisting of Fe, Ni, Mn, Al, Mg, Zn, Ti, La, Ce, Sn, Zr, Ru, Si, Ge, and combinations thereof. In some embodiments, the dopant is not Fe, Ni, Mn, Mg, Zn, Ti, La, Ce, Ru, Si, or Ge. In some embodiments, the dopant is not Al, Sn, or Zr. In some embodiments, the positive electrode active material may include at least one of LiNi0.33Mn0.33Co0.33O2, LiNiO2, LiNi0.4Mn0.4Co0.2O2, LiNi0.5Mn0.3Co0.2O2, LiNi0.6Mn0.2Co0.2O2, LiNi0.7Mn0.15Co0.15O2, LiNi0.8Mn0.1Co0.1O2, LiNi0.92Mn0.04Co0.04O2, and LiNi0.8Co0.15Al0.05O2.

[0063] In some embodiments, the positive electrode binder includes at least one of polyvinylidene fluoride (PVDF), poly(vinylidene fluoride)-hexafluoropropylene (PVDF-HFP), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, polyacrylic acid, polyacrylonitrile, polyimide, polyurethane, polyvinyl butyral, polyvinylpyrrolidone (PVP), acrylic acid-acrylonitrile-acrylamide copolymer, and acrylic acid-acrylonitrile-acrylate copolymer.

[0064] The positive electrode binder of this application is not limited to the materials mentioned above, but also includes other materials that can be used as battery positive electrode binders. In some embodiments, the positive electrode conductive agent may include at least one of carbon, carbon black, graphite, expanded graphite, graphene, graphene nanosheets, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon fibers, carbon nanofibers, graphitized carbon sheets, carbon nanotubes, carbon nanotubes, activated carbon, and mesoporous carbon. The positive electrode conductive agent of this application is not limited to the materials mentioned above, but also includes other materials that can be used as battery positive electrode conductive agents.

[0065] This application also proposes an electronic device including an electrochemical device 10 as described in any of the above embodiments. In this application, a first clearance groove 321 is provided on the first lithium layer 320 of the lithium replenishing electrode 300, and the projection of the first clearance groove 321 accommodates the projection of the negative electrode connection portion 210. Therefore, the portion of the first lithium layer 320 near the negative electrode connection portion 210 has a lower lithium content. When the lithium replenishing electrode 300 replenishes lithium to the negative electrode 100, less lithium migrates from the portion of the first lithium layer 320 near the negative electrode connection portion 210 to the negative electrode 100. The lithium replenishment rate of the portion of the negative electrode 100 near the negative electrode connection portion 210 is lower, resulting in a lower lithium content after replenishment. Therefore, the portion of the negative electrode 100 near the negative electrode connection portion 210 is less prone to lithium plating, and the overall safety of the electronic device is also stronger.

[0066] It should be understood that the electronic device described in this application is not particularly limited, and can be any electronic device known in the prior art. The purpose of this invention is not particularly limited, and it can be used with any electronic device known in the prior art. According to some embodiments of the invention, the electronic device includes, but is not limited to, mobile phones, smartphones, laptops, tablets, wearable devices, smartwatches, smart bracelets, smart glasses, power banks, televisions, game consoles, game controllers, digital cameras, smart speakers, headphones, keyboards, mice, monitors, drones, audio equipment, home appliances, toys, power tools, automobiles, motorcycles, electric bicycles, bicycles, robots, robot dogs, industrial robots, and android robots.

[0067] Although illustrative embodiments have been demonstrated and described, those skilled in the art should understand that the above embodiments should not be construed as limiting the invention, and that changes, substitutions and modifications can be made to the embodiments without departing from the spirit, principles and scope of the invention.

[0068] The embodiments of this application have been described in detail above with reference to the accompanying drawings. However, this application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this application. Furthermore, unless otherwise specified, the embodiments and features described in the embodiments of this application can be combined with each other.

Claims

1. An electrochemical device having a length direction, a width direction, and a thickness direction, characterized in that, include: Negative electrode plate; The negative electrode tab includes a negative electrode connecting part and a negative electrode protrusion connected together, wherein the negative electrode connecting part is connected to the negative electrode sheet; A lithium-filling electrode sheet, stacked on the negative electrode sheet in the thickness direction, includes a lithium-filling current collector and a first lithium layer stacked together; A lithium replenishing tab is connected to the lithium replenishing current collector; the negative electrode tab can be electrically connected to the lithium replenishing tab so that the first lithium layer can replenish lithium to the negative electrode sheet; A first separator is disposed between the lithium-filling electrode and the negative electrode; The lithium replenishing electrode has a first clearance groove on the first lithium layer, and the first clearance groove is recessed relative to the surface of the first lithium layer away from the lithium replenishing current collector; the electrochemical device has a projection plane perpendicular to the thickness direction, the first clearance groove has a first projection on the projection plane, the negative electrode connection has a second projection on the projection plane, and the first projection accommodates the second projection.

2. The electrochemical device according to claim 1, characterized in that, The electrochemical device further includes a positive electrode and a positive electrode tab, the positive electrode tab being connected to the positive electrode; the positive electrode and the negative electrode are wound together around an axis parallel to the length direction to form a winding structure; the winding structure includes straight regions and bent regions arranged along the width direction, and the negative electrode includes a plurality of first straight portions located in the straight regions; The lithium-replenishing electrode is stacked on the first flat portion, and the first separator is located between the first flat portion and the lithium-replenishing electrode.

3. The electrochemical device according to claim 2, characterized in that, The lithium-filled electrode is located on the outside of the wound structure.

4. The electrochemical device according to claim 2, characterized in that, The electrochemical device further includes a second diaphragm disposed between the positive electrode and the negative electrode to separate the positive electrode and the negative electrode. The positive electrode also includes a plurality of second flat portions located in the flat region, and in the thickness direction, the lithium supplement electrode is located on the side of the second separator close to the first flat portion.

5. The electrochemical device according to claim 1, characterized in that, The electrochemical device includes a plurality of negative electrode plates, a plurality of positive electrode plates, a plurality of positive electrode tabs, and a plurality of third membranes. Each positive electrode plate is connected to at least one positive electrode tab. Along the thickness direction, the negative electrode plates and the positive electrode plates are stacked alternately, and the third membranes are provided between adjacent negative electrode plates and positive electrode plates.

6. The electrochemical device according to claim 5, characterized in that, The lithium-filling electrode is located on one side of all the negative electrode electrodes in the thickness direction.

7. The electrochemical device according to claim 5, characterized in that, The lithium-filling electrode is located on the side of the third separator closer to the negative electrode.

8. The electrochemical device according to claim 1, characterized in that, The lithium replenishing electrode tab is integrally connected to the lithium replenishing current collector.

9. The electrochemical device according to claim 1, characterized in that, The electrochemical device includes multiple lithium replenishing tabs, all of which are connected to the lithium replenishing current collector.

10. An electronic device, characterized in that, Includes the electrochemical device as described in any one of claims 1 to 9.

Images