Electrochemical device and electronic apparatus

Abstract

This utility model discloses an electrochemical device and an electronic device. The battery cell has a stacked structure, comprising a first core and a second core stacked along a first direction, forming a stepped structure. The first core includes a first electrode adjacent to the second core, and the second core includes a second electrode adjacent to the second core. The second electrode includes a second current collector and a second active material layer. The surface of the second current collector facing the first electrode includes a first region and a second region distinct from the first region. The second active material layer covers the first region and is correspondingly disposed to the first electrode. A first protective layer covers the second region, thereby balancing the stress on one side of the second current collector and reducing the bending deformation of the second electrode towards the first core. This not only reduces the risk of second current collector breakage but also lowers the internal resistance of the electrochemical device and improves lithium plating performance, thereby enhancing the cycle life and safety of the electrochemical device.

Description

Technical Field

[0001] This utility model relates to the field of electrochemical technology, and in particular to electrochemical devices and electronic equipment. Background Technology

[0002] Stepped cells are formed by combining multiple cells into a stepped structure based on traditional processes to better adapt to the irregular spaces inside terminal devices. Taking stepped laminated cells as an example, they are formed by stacking cores of different sizes. Therefore, for the larger core, only a portion of the electrode facing the smaller core has active material that corresponds to the smaller core and undergoes an electrochemical reaction. As the active material expands and generates stress during the electrochemical reaction, the part of the electrode that does not correspond to the smaller core is only subjected to force on one side, which leads to the warping of the electrode. This not only increases the internal resistance of the cell but may also cause the electrode to break, thus affecting the cycle life and safety of the cell. Utility Model Content

[0003] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes an electrochemical device that can reduce the risk of electrode warping and improve the lifespan and safety of the electrochemical device.

[0004] This invention also provides an electronic device that includes the above-described electrochemical device.

[0005] An electrochemical device according to a first aspect of the present invention includes: a battery cell and a first protective layer.

[0006] The battery cell has a stacked structure, comprising a first core and a second core stacked along a first direction. A plane perpendicular to the first direction is defined as a set surface. Along the first direction, the projection of the first core onto the set surface is a first projection, and the projection of the second core onto the set surface is a second projection. The first projection is within the range of the second projection, and the area of ​​the first projection is smaller than the area of ​​the second projection. The first core includes a first electrode adjacent to the second core, and the second core includes a second electrode adjacent to the first core. The first electrode includes a first current collector and a first active material layer. The first active material layer covers the side of the first current collector facing the second electrode. The second electrode includes a second current collector and a second active material layer. The surface of the second current collector facing the first electrode includes a first region and a second region distinct from the first region. The second active material layer covers the first region and is correspondingly disposed with respect to the first active material layer. The first protective layer covers the second region.

[0007] The electrochemical device according to the embodiments of this utility model has at least the following beneficial effects: In this embodiment, the surface of the second current collector facing the first electrode includes a first region and a second region distinct from the first region. A second active material layer covers the first region and is correspondingly disposed with respect to the first active material layer; a first protective layer covers the second region. That is, in this embodiment, in the current collector (second current collector) of the electrode (second electrode) facing the small core (first core) from the large core (second core), a first protective layer is disposed in the region (second region) where no active material layer is correspondingly disposed. The first protective layer can provide support, thereby balancing the stress on one side of the second current collector, reducing the deformation of the second current collector caused by unilateral force, and thus reducing the bending deformation of the second electrode facing the first core. Therefore, not only can the risk of breakage of the second current collector be reduced, but the internal resistance of the electrochemical device can also be reduced, and the lithium plating situation of the electrochemical device can be improved, thereby enhancing the cycle life and safety of the electrochemical device.

[0008] According to some embodiments of the present invention, the first protective layer has a protrusion on the side facing the second active material layer, the protrusion is embedded in the second active material layer, and in the first direction, the distance between the protrusion and the surface of the second active material layer facing away from the second current collector is greater than 0.

[0009] According to some embodiments of the present invention, the first protective layer is an insulating structure.

[0010] According to some embodiments of the present invention, the first protective layer includes a first structural portion and a second structural portion distributed along a first direction, the first structural portion being connected to a second region, the first structural portion being a conductive structure, the first structural portion including the protrusion, the second structural portion covering the side of the first structural portion away from the second region, and the second structural portion being an insulating structure.

[0011] According to some embodiments of the present invention, the first structural part and the second current collector are an integral structure.

[0012] According to some embodiments of the present invention, the surface of the first protective layer facing away from the second current collector is flush with the surface of the second active material layer.

[0013] According to some embodiments of the present invention, the electrochemical device further includes a second protective layer, which is an insulating structure, and the battery cell is covered with the second protective layer on both sides in the first direction.

[0014] According to some embodiments of the present invention, the first electrode is an anode plate, the second electrode is a cathode plate, and in the first direction, the projection of the first active material layer is a third projection, the projection of the first protective layer is a fourth projection, and the third projection and the fourth projection partially overlap.

[0015] According to some embodiments of the present invention, the battery cell includes a cathode sheet, and the cathode sheet located in the second core is defined as a set cathode sheet. The set cathode sheet includes a set current collector and a set active material layer. The set active material layer covers the surface of the set current collector in the first direction. The set cathode sheet includes two first surfaces disposed opposite to each other in the first direction, and a second surface located between the two first surfaces. The set active material layer has a groove and an opening communicating with the groove. The opening is located on the second surface.

[0016] An electronic device according to a second aspect embodiment of the present invention includes an electrochemical device according to the first aspect embodiment.

[0017] The electronic device according to the embodiments of the present invention has at least the following beneficial effects: In the electrochemical device of the first aspect embodiment, the surface of the second current collector facing the first electrode includes a first region and a second region distinct from the first region. A second active material layer covers the first region and is correspondingly disposed with respect to the first active material layer; a first protective layer covers the second region. That is, in this embodiment, in the current collector (second current collector) of the electrode (second electrode) facing the small core (first core) from the large core (second core), a first protective layer is disposed in the region (second region) where no active material layer is disposed. The first protective layer can provide support, thereby balancing the stress on one side of the second current collector and reducing the deformation of the second current collector caused by unilateral force, thus reducing the bending deformation of the second electrode facing the first core. Therefore, not only can the risk of breakage of the second current collector be reduced, but the internal resistance of the electrochemical device can also be reduced, and the lithium plating situation of the electrochemical device can be improved, thereby increasing the cycle life and safety of the electrochemical device, and further improving the service life and safety of the electronic device of this embodiment.

[0018] Additional aspects and advantages of this invention 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 the invention. Attached Figure Description

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein: Figure 1 This is a cross-sectional view of the first electrochemical device according to the first aspect of the present invention; Figure 2for Figure 1 A schematic diagram of the structure of the first electrode, the second electrode, the separator, and the first protective layer; Figure 3 for Figure 2 Schematic diagram of the structure of the second current collector; Figure 4 This is a cross-sectional view of the battery cell in the second type of electrochemical device according to the first aspect of this utility model; Figure 5 for Figure 4 A magnified view of a portion of region A in the middle; Figure 6 This is a partial cross-sectional view of the battery cell in the third type of electrochemical device according to the first aspect of this utility model; Figure 7 This is a schematic diagram of the structure of the cathode plate in the fourth type of electrochemical device according to the first aspect of this utility model; Figure 8 This is a cross-sectional view of the battery cell in the fifth type of electrochemical device according to the first aspect of this utility model.

[0020] Figure label: Cell 100, anode plate 101, cathode plate 102, separator 103, first core 110, first electrode plate 111, first current collector 1111, first active material layer 1112, second core 120, second electrode plate 121, second current collector 1211, first region 12111, second region 12112, second active material layer 1212, sub-active material layer 12121; First protective layer 200, protrusion 210, first structural part 220, second structural part 230; Outer shell 300, second protective layer 40.

[0021] Set the cathode plate 10, set the current collector 11, set the active material layer 12, groove 1201, opening 1202, first surface 1203, and second surface 1204. Detailed Implementation

[0022] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0023] In the description of this utility model, it should be understood that the directional descriptions, such as up, down, front, back, left, right, etc., indicate the directional or positional relationship based on the directional or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0024] In the description of this utility model, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0025] In the description of this utility model, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this utility model in conjunction with the specific content of the technical solution.

[0026] Stepped cells are formed by combining multiple cells into a stepped structure based on traditional processes to better adapt to the irregular spaces inside terminal devices. Taking stepped laminated cells as an example, they are formed by stacking cores of different sizes. Therefore, for the larger core, only a portion of the electrode facing the smaller core has active material to conduct an electrochemical reaction. As the active material expands and generates stress during the electrochemical reaction, the part of the electrode that does not correspond to the smaller core is only subjected to force on one side, which leads to the warping of the electrode. This not only increases the internal resistance of the cell but may also cause the electrode to break, thus affecting the cycle life and safety of the cell.

[0027] Specifically, taking the case of the second electrode 121 tilting upwards as an example, firstly, if the second electrode 121 tilts upwards towards the first core 110, the distance between the electrode corresponding to the second electrode 121 in the second core 120 will increase, thereby increasing the ion transport path inside the cell 100 and leading to an increase in internal resistance. Furthermore, the tilting of the second electrode 121 causes stress concentration in the second current collector 1211 at the junction of the first region 12111 and the second region 12112, which can easily lead to microcracks or even fracture under long-term cycling.

[0028] In view of the above background, this utility model proposes an electrochemical device that can reduce the degree of warping of the second electrode 121 in this application, thereby improving the lifespan and safety of the electrochemical device. The electrochemical device includes any device in which an electrochemical reaction occurs to convert chemical energy into electrical energy, and specific, non-limiting examples include all types of primary batteries, secondary batteries, fuel cells, solar cells, or capacitors. In particular, this electrochemical device is a lithium secondary battery, including lithium metal secondary batteries, lithium-ion secondary batteries, lithium polymer secondary batteries, or lithium-ion polymer secondary batteries. (See also...) Figures 1 to 3 The electrochemical device in this embodiment includes a battery cell 100 and a first protective layer 200.

[0029] The battery cell 100 has a stacked structure, meaning it includes alternatingly stacked cathode plates 102, anode plates 101, and a separator 103 along a first direction, with the separator 103 located between the cathode plates 102 and the anode plates 101. The electrochemical device also includes, for example, a housing 300, which may be an aluminum shell, a steel shell, or a soft-shell membrane, with the battery cell 100 located within the housing 300 (e.g., ...). Figure 1 (As shown). The battery cell 100 includes a first core stack 110 and a second core stack 120 stacked along a first direction. A plane perpendicular to the first direction is defined as a setting surface. Along the first direction, the projection of the first core stack 110 onto the setting surface is the first projection, and the projection of the second core stack 120 onto the setting surface is the second projection. The first projection is located within the range of the second projection, and the area of ​​the first projection is smaller than the area of ​​the second projection, i.e., the first core stack 110 is smaller than the second core stack 120, forming a stepped structure. The first core stack 110 includes a first electrode 111 adjacent to the second core stack 120, and the second core stack 120 includes a second electrode 121 adjacent to the second core stack 120. The first electrode 111 and the second electrode 121 have opposite polarities. If the first electrode 111 is an anode 101, then the second electrode 121 is a cathode 102; conversely, if the first electrode 111 is a cathode 102, then the second electrode 121 is an anode 101. The first electrode 111 includes a first current collector 1111 and a first active material layer 1112. The first active material covers the side of the first current collector 1111 facing the second electrode 121. The second electrode 121 includes a second current collector 1211 and a second active material layer 1212 (e.g., ...). Figure 2 (As shown).

[0030] Taking the first electrode 111 as the anode plate 101 as an example, the first current collector 1111 is the anode current collector, which can be a metal foil, foamed metal, or a composite current collector. For example, in some embodiments, the metal foil is copper foil. The composite current collector can include an insulating polymer substrate and a conductive layer disposed on at least one side of the insulating polymer substrate. The first active material layer 1112 is the anode active material layer, which is formed by coating and rolling an anode active material onto the anode current collector. The anode active material can be an anode active material known in the art for use in batteries. As an example, the anode active material can include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. Silicon-based materials can be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials can be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as anode active materials for electrochemical devices can also be used. These anodic active materials can be used alone or in combination of two or more.

[0031] Taking the first electrode 111 cathode plate 102 as an example, the first current collector 1111 is a cathode current collector, and the cathode current collector (positive electrode current collector) is a metal foil or a composite current collector. In some embodiments, the metal foil is aluminum foil. The composite current collector may include an insulating polymer substrate and a conductive layer disposed on at least one side of the insulating polymer substrate. Correspondingly, the first active material layer 1112 is a cathode active material layer, which is formed by coating and rolling a cathode active material onto the cathode current collector. The cathode active material includes one or more of lithium phosphate, lithium transition metal oxide, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as cathode active materials for electrochemical devices can also be used. These cathode active materials can be used alone or in combination of two or more. Examples of lithium phosphates include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co0.1Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05 At least one of O2 and its modified compounds.

[0032] Similarly, the second electrode 121 can be either an anode 101 or a cathode 102, as long as it is electrically opposite to the first electrode 111.

[0033] The surface of the second current collector 1211 facing the first electrode 111 includes a first region 12111 and a second region 12112 that is distinct from the first region 12111 (e.g., ...). Figure 2 and Figure 3As shown, the second active material layer 1212 covers the first region 12111 and is correspondingly disposed with respect to the first active material layer 1112; the first protective layer 200 covers the second region 12112. That is, in this embodiment, the surface of the second current collector 1211 facing the first electrode 111 includes a first region 12111 and a second region 12112 that is distinct from the first region 12111. The second active material layer 1212 covers the first region 12111 and is correspondingly disposed with respect to the first active material layer 1112. The first protective layer 200 covers the second region 12112. In this embodiment, in the current collector (second current collector 1211) of the electrode (second electrode 121) facing the small core (first core 110) from the large core (second core 120), a first protective layer 200 is provided in the region (second region 12112) where no active material layer is provided. The first protective layer 200 can provide support, thereby balancing the stress on one side of the second current collector 1211 and reducing the deformation of the second current collector 1211 caused by unilateral force, thus reducing the bending deformation of the second electrode 121 towards the first core 110. That is, compared with a single layer of second current collector 1211, the whole formed by the second current collector 1211 and the first protective layer 200 in this embodiment has higher bending stiffness and tensile strength. Therefore, it can not only reduce the risk of fracture of the second current collector 1211, but also reduce the internal resistance of the electrochemical device and improve the lithium plating situation of the electrochemical device, thereby improving the cycle life and safety of the electrochemical device.

[0034] It should be noted that the first protective layer 200 can be made of a non-metallic insulating material, such as magnesium oxide, aluminum oxide, tungsten oxide, titanium oxide, silicon dioxide, boehmite, epoxy resin, etc. When the first protective layer 200 is made of a metallic material, it is preferably a metallic material that is the same as or electrochemically compatible with the second current collector 1211. For example, if the second current collector 1211 is aluminum foil, the first protective layer 200 can be made of aluminum oxide or metallic aluminum; if the second current collector 1211 is copper foil, the first protective layer 200 can be made of nickel, titanium, or their oxides. Regardless of whether the material is metallic or non-metallic, the goal is to reduce the bending deformation of the second current collector 1211 due to unilateral stress, while ensuring the safety of the electrochemical device.

[0035] Furthermore, it should be noted that the first core 110 and the second core 120 are not limited to a square structure, but can also be any shape such as circular or triangular. The shapes of the first core 110 and the second core 120 can be the same or different, as long as a stepped structure is formed. In some embodiments, the first protective layer 200 has a protrusion 210 on the side facing the second active material layer 1212. The protrusion 210 is embedded in the second active material layer 1212, and in the first direction, the distance between the protrusion 210 and the surface of the second active material layer 1212 facing away from the second current collector 1211 is greater than 0. Therefore, during charging and discharging, the expansion of the second active material layer 1212 can press the protrusion 210 tightly against the second current collector 1211, thereby forming a cantilever structure with one end fixed, thus enhancing its effect on suppressing deformation of the second current collector 1211.

[0036] In some embodiments, the first protective layer 200 is an insulating structure. As described above, the first protective layer 200 is made of one or more materials selected from materials such as magnesium oxide, aluminum oxide, tungsten oxide, titanium oxide, silicon dioxide, boehmite, and epoxy resin. Thus, the first protective layer 200 not only suppresses deformation of the current collector but also acts as an insulator between the second current collector 1211 and the outer casing 300, thereby improving the safety performance of the electrochemical device. Specifically, during the use of the electrochemical device, if an accident such as impact or compression occurs, the first protective layer 200 may become embedded in the second core 120. Since the first protective layer 200 is an insulating structure, the cathode plate 102 and anode plate 101 in the second core 120 will not conduct through the first protective layer 200 due to its embedding. This reduces the risk of a short circuit in the second core 120, effectively reducing the risk of thermal runaway caused by an internal short circuit and further improving the safety performance of the electrochemical device. Similarly, in some embodiments, the electrochemical device further includes a second protective layer 40, which is an insulating structure. The second protective layer 40 is made of one or more materials such as magnesium oxide, aluminum oxide, tungsten oxide, titanium oxide, silicon dioxide, boehmite, and epoxy resin, so that the battery cell 100 has insulating protective layers on both sides of the outermost layer in the first direction, further improving the overall safety of the electrochemical device.

[0037] Furthermore, it should be noted that when the second electrode 121 in this embodiment is the cathode 102, that is, the second active material layer 1212 is the cathode active material, correspondingly, the first active material layer 1112 located on the first electrode 111 is the anode active material. In order to improve the lithium plating situation of the cell 100, the anode active material needs to protrude from the cathode active material to meet the OH (OverHang, referring to the part of the cathode 102 that extends beyond the anode 101) requirement of the cell 100, thereby ensuring that there is enough anode material to accommodate the lithium ions that are extracted from the cathode, and avoiding excessive accumulation of lithium ions at the edge of the anode, which would lead to lithium plating. However, since the portion of the first electrode 111 protruding from the second active material layer 1212 is suspended, the edge of the first electrode 111 may deform toward the second current collector 1211 when the electrochemical device is squeezed. Based on this, the first protective layer 200 in this embodiment is an insulating structure, which together with the separator 103 forms a double insulating protection to avoid the risk of short circuit caused by electrical connection between the first electrode 111 and the second current collector 1211 due to wrinkles or damage to the separator 103 (such as being punctured by burrs on the edge of the first current collector 1111).

[0038] Reference Figure 4 and Figure 5 In some embodiments, the first protective layer 200 has a protrusion 210 on the side facing the second active material layer 1212. The protrusion 210 is embedded in the second active material layer 1212, and in a first direction, the distance between the protrusion 210 and the second active material layer 1212 away from the second current collector 1211 is greater than 0. Therefore, during charging and discharging, the expansion of the second active material layer 1212 can press the protrusion 210 against the second current collector 1211, thereby making the first protective layer 200 form a cantilever structure with one end fixed, thus enhancing its effect on suppressing the deformation of the second current collector 1211. Similarly, in some embodiments, the first electrode 111 is an anode 101, and the second electrode 121 is a cathode 102. In the first direction, the projection of the first active material layer 1112 is a third projection, and the projection of the first protective layer 200 is a fourth projection. The third and fourth projections partially overlap, meaning that the first active material layer 1112 protrudes from the edge of the second active material layer 1212 to meet OH design requirements. During charging and discharging, the first active material layer 1112, which protrudes from the second active material layer 1212, experiences volume expansion due to lithium ion insertion and extraction. The resulting stress is transmitted through the separator 103 to the first protective layer 200, thereby creating pressure on the first protective layer 200. This causes one end of the first protective layer 200 to be clamped between the second current collector 1211 and the separator 103, thus forming a cantilever structure with one end fixed.

[0039] Furthermore, as described above, when the first protective layer 200 is an insulating structure, the protrusion 210 of the first protective layer 200 is embedded in the second active material layer 1212. This avoids the risk of gaps appearing at the interface between the second active material layer 1212 and the first protective layer 200 due to expansion and contraction during charge-discharge cycles, thereby preventing the second current collector 1211 from being exposed through these gaps and thus avoiding the risk of a short circuit between the exposed second current collector 1211 and the first electrode 111. Specifically, in the direction from the first protective layer 200 to the second active material layer 1212, the size of the protrusion 210 is L, that is, the size by which the protrusion 210 is embedded in the second active material layer 1212 is L, where 0 < L ≤ 5 mm. L can be, for example, 0.1 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, or 5 mm, or any value within any two of the above ranges. Specifically, if L < 0 mm, the first protective layer 200 and the second active material layer 1212 cannot form an effective interlock, resulting in a gap that may expose the second current collector 1211 and cause a short circuit risk. If L > 5 mm, it will lead to excessive loss of active material, affecting the energy density of the cell 100. Based on this, L satisfies 0 < L ≤ 5 mm, keeping it within a reasonable value range, which can both improve the safety of the electrochemical device and ensure the energy density of the electrochemical device.

[0040] Reference Figure 6In some embodiments, the first protective layer 200 includes a first structural portion 220 and a second structural portion 230 distributed along a first direction. The first structural portion 220 is connected to the second region 12112 and is a conductive structure. The first structural portion 220 includes a protrusion 210. The second structural portion 230 covers the side of the first structural portion away from the second region 12112 and is an insulating structure. Specifically, the first structural portion 220 is a conductive structure, including a protrusion 210. The protrusion 210 is conductive, allowing the current collector to achieve electrical connection with the portion of the second active material layer 1212 corresponding to the protrusion 210 (for ease of explanation, the portion of active material between the protrusion 210 and the first active material layer 1112 is defined as the sub-active material layer 12121, i.e., the sub-active material layer 12121 is located on the side of the protrusion 210 away from the second current collector 1121). In this embodiment, the protrusion 210 is conductive, so in the electrochemical reaction, electrons can be directly conducted to the sub-active material layer 12121 through the protrusion 210, thereby shortening the electron conduction path, reducing interface impedance, and improving the efficiency of the electrochemical reaction. The second structural portion 230 is an insulating structure, providing insulation protection and reducing the risk of short circuit between the first electrode 111 and the second current collector 1211. In this embodiment, the first protective layer 200 serves as both an insulating protection layer between the first electrode 111 and the second current collector 1211, improving the safety of the electrochemical device in this embodiment, and also shortens the electron transport path between the second current collector 1211 and the sub-active material layer 12121, thereby improving conductivity.

[0041] It should be noted that when the first electrode 111 is a cathode 102, the first structural part 220 is made of aluminum, which is the same material as the cathode current collector. When the first electrode 111 is an anode 101, the first structural part 220 is made of copper, which is the same material as the anode current collector. The first structural part 220 is connected to the second region 12112 of the second current collector 1211 by bonding or welding with conductive adhesive. Alternatively, as in some embodiments, the first structural part 220 and the second current collector 1211 are integrally formed by an integral molding process.

[0042] Reference Figure 2In some embodiments, the surface of the first protective layer 200 facing away from the second current collector 1211 is flush with the surface of the second active material layer 1212. Therefore, when coating the second active material layer 1212, stress concentration caused by a sudden change in thickness at the boundary between the first region 12111 and the second region 12112 can be avoided, thereby reducing the risk of breakage of the second current collector 1211. Specifically, during the processing, the first protective layer 200 is first set in the second region 12112. The first protective layer 200 is set by methods including but not limited to deposition, spraying, bonding, or welding. After the first protective layer 200 is set, the second active material layer 1212 is formed by coating and rolling in the first region 12111. The presence of the first protective layer 200 makes the surface of the second current collector 1211 smoother, and stress concentration at the boundary can be reduced during rolling, thereby effectively reducing the risk of mechanical damage to the second current collector 1211 during the processing.

[0043] Reference Figure 7 In some embodiments, the battery cell 100 includes a cathode sheet 102. The cathode sheet 102 located in the second core 120 is defined as a set cathode sheet 10. The set cathode sheet 10 includes a set current collector 11 and a set active material layer 12. The set active material layer 12 covers the surface of the set current collector 11 in a first direction. The set cathode sheet 10 includes two first surfaces 1203 arranged opposite to each other in the first direction, and a second surface 1204 located between the two first surfaces 1203. The set active material layer 12 has a groove 1201 and an opening 1202 communicating with the groove 1201. The opening 1202 is located on the second surface 1204. The groove 1201 is formed, for example, by laser processing, mechanical scribing, chemical etching or embossing. The cross-section of the groove 1201 includes, but is not limited to, a rectangle, trapezoid, semicircle, U-shape or V-shape. The number of grooves 1201 can be one or more, which are designed according to actual needs.

[0044] Specifically, it can be understood that during the manufacturing process of the battery cell 100, the materials of each layer are stacked sequentially and tightly bonded through a rolling process to ensure good interface contact. As a result, the gaps between the cathode sheet 102 and the anode sheet 101 and the separator 103 in the battery cell 100 are also small. In order to ensure that the electrolyte can quickly wet the entire interior of the battery cell 100, in this embodiment, the active material layer of the cathode sheet 102 in the second core stack 120 is provided with a groove 1201, and the groove 1201 extends to the side of the active material layer, or penetrates the active material layer in a direction perpendicular to the first direction, forming an opening 1202. Therefore, the electrolyte can enter the groove 1201 through the opening 1202 and quickly penetrate into the gaps between the layers inside the battery cell 100 through the groove 1201, significantly improving the injection efficiency and wettability. The reason why the cathode plate 102 of the second core 120 has a groove 1201 is that the second core 120 is larger in size than the first core 110, so the central region of the second core 120 is more difficult to be wetted by the electrolyte than the first core 110. The first core 110 does not have a groove 1201, which ensures the energy density of the first core 110, and thus ensures the energy density of the electrochemical device in this embodiment. Furthermore, in some embodiments, the electrochemical device also includes a housing 300 with an injection hole for injecting electrolyte into the housing 300. The opening 1202 is oriented towards the injection hole, allowing the electrolyte to flow rapidly along the groove 1201 during injection, further improving the wetting efficiency.

[0045] Furthermore, based on the above implementation, the grooves 1201 on the active material layers 12 on both sides of the current collector 11 are staggered to avoid the reduction in structural strength of the cathode sheet 10 caused by the alignment of the grooves 1201 on both sides, and to avoid the risk of damage caused by repeated mechanical stress or high temperature on the same area of ​​the current collector 11 during processing. For example, the grooves 1201 are formed by an embossing process. The staggered arrangement of the grooves 1201 can avoid repeated stress on the same position, which could cause cracks in the current collector 11, thereby ensuring the mechanical properties of the cathode sheet 10 and improving the overall structural stability of the cell 100.

[0046] The electronic device according to the second aspect of the present invention is not particularly limited to any electronic device known in the prior art, including but 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, android robots, etc.

[0047] The electronic device of this embodiment includes the electrochemical device of the first aspect embodiment. In the electrochemical device, the surface of the second current collector 1211 facing the first electrode 111 includes a first region 12111 and a second region 12112 that is different from the first region 12111. The second active material layer 1212 covers the first region 12111 and is correspondingly disposed with respect to the first active material layer 1112. The first protective layer 200 covers the second region 12112. That is, in this embodiment, in the current collector (second current collector 1211) of the electrode (second electrode 121) of the large core (second core 120) facing the small core (first core 110), the first protective layer 200 is disposed in the region (second region 12112) where no active material layer is disposed. The first protective layer 200 can play a supporting role, thereby balancing the stress on one side of the second current collector 1211 and reducing the deformation of the second current collector 1211 caused by the force on one side, so as to reduce the bending deformation of the second electrode 121 facing the first core 110. Therefore, not only can the risk of breakage of the second current collector 1211 be reduced, but the internal resistance of the electrochemical device can also be reduced, and the lithium plating situation of the electrochemical device can be improved, thereby improving the cycle life and safety of the electrochemical device, and thus improving the service life and safety of the electronic device in this embodiment.

[0048] It should be noted that since the electronic device of this embodiment adopts all the technical features of the electrochemical device of the first aspect embodiment, the electronic device of this embodiment has all the beneficial effects brought by the first aspect embodiment, which will not be repeated here.

[0049] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention. Furthermore, in the description of the present invention, the reference to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicates that the specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples.

Claims

1. An electrochemical device, characterized in that, include: A battery cell, wherein the battery cell has a stacked structure, the battery cell includes a first stack and a second stack of cores stacked along a first direction, a plane perpendicular to the first direction is defined as a setting plane, along the first direction, the projection of the first stack of cores onto the setting plane is a first projection, the projection of the second stack of cores onto the setting plane is a second projection, the first projection is located within the range of the second projection, and the area of ​​the first projection is smaller than the area of ​​the second projection; and, The first core includes a first electrode adjacent to the second core, and the second core includes a second electrode adjacent to the first core. The first electrode includes a first current collector and a first active material layer. The first active material layer covers the side of the first current collector facing the second electrode. The second electrode includes a second current collector and a second active material layer. The surface of the second current collector facing the first electrode includes a first region and a second region different from the first region. The second active material layer covers the first region and is correspondingly disposed with respect to the first active material layer. A first protective layer covers the second area.

2. The electrochemical device according to claim 1, characterized in that, The first protective layer has a protrusion on the side facing the second active material layer. The protrusion is embedded in the second active material layer, and in the first direction, the distance between the protrusion and the surface of the second active material layer facing away from the second current collector is greater than 0.

3. The electrochemical device according to claim 1 or 2, characterized in that, The first protective layer is an insulating structure.

4. The electrochemical device according to claim 2, characterized in that, The first protective layer includes a first structural portion and a second structural portion distributed along a first direction. The first structural portion is connected to the second region. The first structural portion is a conductive structure and includes the protrusion. The second structural portion covers the side of the first structural portion away from the second region and is an insulating structure.

5. The electrochemical device according to claim 4, characterized in that, The first structural part and the second current collector are an integral structure.

6. The electrochemical device according to claim 1, characterized in that, The surface of the first protective layer facing away from the second current collector is flush with the surface of the second active material layer.

7. The electrochemical device according to claim 1, characterized in that, The electrochemical device further includes a second protective layer, which is an insulating structure, and the battery cell is covered with the second protective layer on both sides in the first direction.

8. The electrochemical device according to claim 1, characterized in that, The first electrode is an anode, the second electrode is a cathode, and in the first direction, the projection of the first active material layer is a third projection, the projection of the first protective layer is a fourth projection, and the third projection and the fourth projection partially overlap.

9. The electrochemical device according to claim 1, characterized in that, The cell includes a cathode sheet, and the cathode sheet located in the second core is defined as a set cathode sheet. The set cathode sheet includes a set current collector and a set active material layer. The set active material layer covers the surface of the set current collector in the first direction. The set cathode sheet includes two first surfaces arranged opposite to each other in the first direction, and a second surface located between the two first surfaces. The set active material layer has a groove and an opening communicating with the groove. The opening is located on the second surface.

10. An electronic device, characterized in that, The electrochemical device includes any one of claims 1 to 9.

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