Electrochemical device and power consumption device

Abstract

This application relates to the field of electrochemistry technology and discloses an electrochemical device and a power consumption device. The electrochemical device includes a case assembly and an electrode assembly housed in the case assembly. The case assembly includes a case and a lid. The case includes a bottom wall and side walls. One end of each side wall is connected to the bottom wall, and the other end extends away from the bottom wall. The bottom wall and the side walls together define a housing chamber. The lid is attached to one end of the side wall that extends away from the bottom wall to cover the housing chamber. The direction from the bottom wall towards the lid is defined as the first direction. The electrode assembly includes a first electrode sheet, a second electrode sheet, and a separator. The first electrode sheet includes a first electrode sheet unit, and the second electrode sheet includes a second electrode sheet unit. The first electrode sheet unit and the second electrode sheet unit are stacked along the second direction and are both provided perpendicular to the second direction. A separator is provided between the adjacent first electrode sheet unit and second electrode sheet unit. The second direction is perpendicular to the first direction. With this electrochemical device, it is possible to improve the current situation where deformation and cracks are likely to occur in the current electrochemical device.

Description

Cross-reference to Related Applications

[0001] This application claims priority based on a Chinese patent application with an application number of 202210684872.9 and a title of "Electrochemical Device and Power Consumption Device", which was filed with the China National Intellectual Property Administration on June 13, 2022. All of its content is incorporated herein by reference.

Technical Field

[0002] This application relates to the field of electrochemical technology, and particularly to electrochemical devices and power consumption devices.

Background Art

[0003] An electrochemical device is a device that converts external energy into electrical energy and stores it internally, and supplies power to an external power consumption device (such as a portable power consumption device, an electric vehicle, an electric tool, an electric bicycle, etc.) as needed.

[0004] Generally, an electrochemical device includes a case assembly, an electrode assembly, and a tab or pole structure for leading out the polarity of the electrode assembly from the case assembly. Here, the case assembly includes a case and a lid. A storage chamber is provided at one end of the case, and the lid is attached to the open end of the storage chamber to cover the storage chamber. The electrode assembly is accommodated in the above storage chamber and includes a first electrode sheet, a second electrode sheet, and a separator that are stacked and installed. The first electrode sheet and the second electrode sheet have opposite polarities, and a separator for separation is provided between them.

[0005] In an electrochemical device in which the electrode assembly has a laminated structure, the lamination direction of the first electrode sheet and the second electrode sheet coincides with the direction in which the above case faces the lid. In this electrochemical device, during charging, the electrode assembly expands significantly along the above lamination direction. At the same time, the case and the lid are not of an integral structure and are usually sealed by welding. In this case, since the case and the lid are thin and the welding area between the two is small, when the pressure inside the case rises, the welded part is likely to become a vulnerable area. Therefore, the strength of the case assembly in the above lamination direction is low, and due to the expansion and deformation of the electrode assembly, the case assembly is also likely to deform and crack in the above lamination direction, further causing phenomena such as electrolyte leakage, and the mountability of the electrochemical device is low.

Summary of the Invention

Problems to be Solved by the Invention

[0006] An object of the present application is to provide an electrochemical device and a power consumption device in order to improve the current situation where cracks are likely to occur in the case assembly of the electrochemical device.

Means for Solving the Problems

[0007] In order to solve its technical problems, the present application adopts the following technical means.

[0008] An electrochemical device comprising a case assembly and an electrode assembly. The case assembly includes a case and a lid. The case includes a bottom wall and side walls. One end of each side wall is connected to the bottom wall, and the other end extends away from the bottom wall. The bottom wall and the side walls together define a housing chamber. The lid is attached to the end of the side wall that extends away from the bottom wall to cover the housing chamber. The direction from the bottom wall towards the lid is defined as the first direction. The electrode assembly is housed in the housing chamber and includes a first electrode sheet, a second electrode sheet, and a separator. The first electrode sheet includes a first electrode sheet unit, and the second electrode sheet includes a second electrode sheet unit. The first electrode sheet unit and the second electrode sheet unit are stacked along a second direction and are both provided perpendicular to the second direction. The separator is provided between adjacent first electrode sheet units and second electrode sheet units. Here, the second direction is perpendicular to the first direction.

[0009] In the electrochemical device according to the embodiment of the present application, since the stacking direction of each first electrode sheet unit and each second electrode sheet unit is perpendicular to the first direction of the case, in the process of charging the electrochemical device, the electrode assembly mainly expands along the second direction, and the degree of expansion in the first direction is extremely small. Therefore, the case is also less likely to expand and deform in the first direction.

[0010] In summary, the electrochemical device according to the embodiment of the present application can improve the current situation where the current electrochemical device is prone to deformation and cracking. In the electrochemical device, the electrode sheets are laminated in the second direction, the degree of expansion of the cell in the first direction is small, and the expansion force of the cell is mainly received by the side wall of the battery case. The side wall of the battery case is usually integrally formed. Even if the side wall is welded, the side walls at the welding location partially overlap each other, and due to the high welding strength, the strength of the side wall in the second direction is high, and the expansion of the cell in the second direction is suppressed by the side wall of the battery case and is not easily deformed. Therefore, the degree of expansion of the entire electrochemical device is small, and thus no expansion occurs. Therefore, it is not necessary to provide a reserve space between the electrode assembly and the case in the above direction within the case for this electrochemical device, so the energy density of this electrochemical device can be further increased. That is, the electrochemical device according to the embodiment of the present application can improve the current situation where it is prone to expand and deform in the first direction after increasing the energy density.

[0011] In some embodiments, the above side wall is integrally formed, and the tensile strength of the material of the side wall is 1000 MPa or more. This is to ensure that the side wall has sufficient strength to resist the deformation of the electrode assembly.

[0012] In some embodiments, the above side wall is formed by welding, and the welding strength at the welding location may be 1000 MPa or more. Since the welding location is prone to become a weak point of deformation and fracture, by setting the tensile strength of the welding location to 1000 MPa or more, it can be ensured that the side wall does not deform when receiving the expansion of the electrode assembly.

[0013] In some embodiments, the first electrode sheet is an anode sheet. The first electrode sheet includes a first current collector and a first active material layer provided on the surface of the first current collector. The material of the first active material layer contains silicon element, and the percentage of the mass of the silicon element in the total mass of the first active material layer is 10% or more. Since silicon-based negative electrode active materials have the advantages of high gram capacity and low potential compared with carbon-based negative electrode active materials, such an arrangement is advantageous for increasing the energy density of the electrochemical device. However, during the cycling process of the cell, the expansion rate of the silicon-based negative electrode active material is large. After lithium is completely occluded, the volume of silicon expands by about 300%. However, the strength of the packaging bag of the conventional soft pack battery cannot withstand the expansion of the silicon negative electrode cell. Therefore, the silicon negative electrode cell is usually packaged in a hard case such as a steel case. However, the conventional laminated battery with a steel case is laminated along the thickness direction of the case. Due to the expansion of the high-silicon system, there is still a problem that it is easily broken at the welding position of the upper and lower cases due to deformation. In the actual process, in order to prevent the expansion of the silicon negative electrode laminated battery, it is necessary to reserve an expansion space of about 10% in the thickness direction in advance, which greatly affects the battery energy density. The stacking form described in the present application is particularly suitable for silicon negative electrode stacked cells, can eliminate the preliminary expansion space, increase the energy density, and suppress the expansion of the battery.

[0014] In some embodiments, preferably, the percentage of the mass of the silicon element in the total mass of the first active material layer is 30% or more and 80% or less. Since the silicon-based negative electrode active material has the characteristics of high gram capacity and high expansion, if the total mass of the silicon element in the first active material layer is less than 30%, the role of increasing the energy density of the electrochemical device is limited. When the content of the silicon element in the first active material layer exceeds 80%, the energy density of the electrochemical device can be maximally increased, but the degree of expansion of the anode sheet becomes very large. Due to the suppression by the high-rigidity side wall, the expansion force of the anode sheet is converted into the pressing force between the electrode sheets of the electrode assembly, and a periodic pressing force is applied to each electrode sheet in the process of repeating the charge and discharge cycle of the electrochemical device, which may cause defects such as the dropout of the active material and the precipitation of lithium, and has a certain impact on the cycle life of the electrochemical device.

[0015] In some embodiments, the first active material layer includes at least one of silicon, silicon-based oxides, silicon carbide, silicon nanowires, and silicon nanoparticles.

[0016] In some embodiments, the electrochemical device further includes a first conductive member. The first electrode sheet includes a first current collector and a first active material layer. The first current collector includes a first region and a second region. The first region is provided perpendicular to the second direction. The second region is electrically connected to the first region. The first active material layer is provided on the surface of the first region, and the first region and the first active material layer together constitute the first electrode sheet unit. Each of the first electrode sheet units is provided at intervals along the second direction, and the second region is electrically connected to the first conductive member.

[0017] In some embodiments, the case has a first sidewall unit and a second sidewall unit oppositely disposed along a third direction. Each of the second regions and the first conductive member is located between the first region and the first sidewall unit. The third direction is perpendicular to the first direction and the second direction respectively. The second region includes a first portion and a second portion. One end of the first portion is connected to the first region, and the other end extends close to the first sidewall unit. The second portion is connected to one end of the first portion away from the first region and is provided by being bent with respect to the first portion. The second portion is connected to the first conductive member.

[0018] In some embodiments, the electrode assembly includes three or more first electrode sheets. The second portion is provided by being bent with respect to the first portion, and the bending directions of each of the second portions are the same. Along a first predetermined direction, between any two adjacent second portions, at least a part of the second portion located on the downstream side is laminated on the surface of the second portion located on the upstream side, and there is no common lamination region between any three adjacent second portions, that is, each second portion is provided by overlapping in order. Here, the first predetermined direction is a direction from one end of the second portion close to the first portion to the other end away from the first portion.

[0019] In other embodiments, each of the above second portions may be provided by being laminated in order along the third direction. However, such an installation form needs to reserve a large space between the first region and the first sidewall unit in advance. In contrast, the form in which each of the second portions in this embodiment is provided by overlapping in order can solve the above deficiency.

[0020] In some embodiments, a first insulating tape is further provided. The electrode assembly has a first surface and a second surface facing each other along the second direction. One end of the first insulating tape is fixed to the first surface, and the other end is fixed to the second surface. The first insulating tape is in a tension state.

[0021] In this way, by sandwiching the electrode assembly between both ends of the first insulating tape, the risk of relaxation deformation between the first electrode sheet unit, the second electrode sheet, and the separator can be reduced.

[0022] In some embodiments, a second insulating tape is further provided. The second insulating tape is fixed to the electrode assembly and the case, respectively, so as to fix the electrode assembly to the case.

[0023] In some embodiments, the electrochemical device includes two or more of the electrode assemblies, and each of the electrode assemblies is arranged along the second direction.

[0024] The installation form in which a plurality of electrode assemblies are stacked can avoid the thickness of a single electrode assembly being too thick, thereby facilitating the lamination process of each electrode assembly and reducing the error rate during the lamination of the electrode assembly.

[0025] In some embodiments, a pole attached to the case is further provided. The pole is insulated from the case, and the pole is electrically connected to the second electrode sheet unit.

[0026] In this way, the pole is configured as one of the conductive terminals in this electrochemical device, thereby realizing the extraction of the polarity of the second electrode sheet.

[0027] In some embodiments, a pressure relief portion is provided in the case. The pressure relief portion is for communicating the accommodation chamber with the outside air of the case when the temperature of the electrochemical device is higher than a preset threshold value.

[0028] Considering that the temperature of the electrochemical device is too high, the gas generation inside the case will cause the air pressure to rise, which may lead to the explosion of the electrochemical device and pose a high safety risk. When the temperature of the electrochemical device is higher than a preset threshold value, the pressure relief part can communicate the accommodation chamber with the outside air of the case and further discharge the gas inside the accommodation chamber to the outside, thereby eliminating the above-mentioned risk.

[0029] In some embodiments, a liquid injection hole is provided in the bottom wall or the lid. Thereby, when injecting the electrolytic solution into the accommodation chamber, the electrolytic solution can penetrate into the gap between the first electrode sheet unit, the separator and the second electrode sheet unit from the beginning, thereby increasing the penetration rate of the electrode assembly, and further shortening the manufacturing cycle of the electrochemical device to a certain extent.

[0030] In some embodiments, the liquid injection hole is provided in the lid, and the distance between the liquid injection hole and the geometric center of the lid is less than 5 mm. Alternatively, the liquid injection hole is provided in the bottom wall, and the distance between the liquid injection hole and the geometric center of the bottom wall is less than 5 mm. Thereby, the penetration rate of the electrolytic solution into the electrode assembly can be increased.

[0031] In some embodiments, when viewed along the first direction, the edge of the bottom wall does not exceed the end of the side wall close to the bottom wall, and when viewed along the first direction, the edge of the lid does not exceed the end of the side wall close to the lid. In this way, under the condition that the case provides an accommodation chamber with sufficient volume, the volume of the entire electrochemical device or the volume occupied when the electrochemical device is incorporated into the power consumption device can be made as small as possible.

[0032] In some embodiments, the aspect ratios of the first electrode sheet and the second electrode sheet are both 3 to 20. When other conditions are the same, the impedance of the electrode sheet is greatly affected by its length. If the aspect ratio of the electrode sheet is too large, that is, if the length of the electrode sheet is too long relative to the width, due to the too large aspect ratio, the impedance of a single electrode sheet increases, and further the internal resistance of the battery increases, and the advantage of the low impedance of the multi-tab laminated battery cannot be fully exerted. If the aspect ratio of the electrode sheet is too small, that is, if the length of the electrode sheet is too short relative to the width, the space occupied by the tab at the end in the length direction becomes large relative to the overall length, which is disadvantageous for fully exerting the effect of improving the volume utilization rate according to this technical solution.

[0033] In order to solve its technical problems, the present application further adopts the following technical means.

[0034] A power consumption device comprising the above electrochemical device. Since this power consumption device comprises the electrochemical device in the above embodiment, the current situation that the current electrochemical device is prone to expand and deform in the first direction can be improved.

Brief Description of the Drawings

[0035] Hereinafter, in order to more clearly explain the technical solutions in the embodiments of the present application, the drawings necessary for the embodiments will be briefly described. It should be noted that the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on the structures shown in these drawings without the need for creative labor.

[0036]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Description of Reference Numerals

[0037] 1 Electrochemical device, 100: Case assembly, 110: Case, 120: Lid, 130: Pressure relief part, 111: Bottom wall, 112: Side wall, 1121: First side wall unit, 1122: Second side wall unit, 1123: Third side wall unit, 1124: Fourth side wall unit, 101: Accommodation chamber, 102: Liquid injection hole, 200: Electrode assembly, 210: First electrode sheet, 220: Second electrode sheet, 230: Separator, 240: First insulating tape, 250: Second insulating tape, 211: First electrode sheet unit, 212: First current collector, 213: First active material layer, 2121: First region, 2122: Second region, 2123: First part, 2124: Second part, 221: Second electrode sheet unit, 222: Second current collector, 223: Second active material layer, 2221: Third region, 2222: Fourth region, 2223: Third part, 2224: Fourth part, 201: First surface, 202: Second surface, 300: First conductive member, 400: Second conductive member, 500: Pole, Z: First direction, X: Second direction, Y: Third direction, M: First predetermined direction, N: Second predetermined direction, 1b: Electrochemical device, 200b: Electrode assembly, 210b: First electrode sheet, 220b: Second electrode sheet, 211b: First electrode sheet unit, 214b: First connection unit, 2101b: First side, 221b: Second electrode sheet unit, 224b: Second connection unit, 2201b: Second side, 2: Power consumption device.

Best Mode for Carrying Out the Invention

[0038] Hereinafter, for the purpose of facilitating the understanding of the present application, the present application will be described in more detail by combining the drawings and specific embodiments. In addition, when a component is described as being "fixed to" / "fixedly connected to" another component, the said component may be directly disposed on the other component, or there may be one or more intermediate components between the said component and the other component. When one component is described as being "connected to" another component, the said one component may be directly connected to the other component, or there may be one or more intermediate components between the said one component and the other component. The terms "vertical", "horizontal", "left", "right", "inside", "outside" and similar expressions used in this specification are for illustrative purposes only.

[0039] Unless otherwise specified, the meanings of all technical terms and scientific terms used in this specification are the same as those generally understood by those skilled in the art. The terms used in this specification are for the purpose of describing specific embodiments only and are not intended to limit the present application. The term "and / or" used in this specification includes any combination and all combinations of one or more of the related listed items.

[0040] In addition, the technical features according to different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0041] In this specification, the above-mentioned "attach" includes fixing or restricting a certain part or device to a specific position or place by welding, screwing, engaging, adhesion, etc. The said part or device can be kept stationary at a specific position or place, and can also move within a limited range. After the said part or device is fixed or restricted to a specific position or place, it may be removable or non-removable. In the embodiments of the present application, there is no limitation.

[0042] Referring to FIGS. 1 to 3, FIGS. 1 to 3 respectively show a schematic perspective view, a schematic exploded view, and a schematic cross-sectional view of an electrode assembly along line A-A in FIG. 2 of an electrochemical device 1 according to an embodiment of the present application. This electrochemical device 1 includes a case assembly 100 and an electrode assembly 200. Here, the case assembly 100 includes a case 110 and a lid 120. The case 110 includes a bottom wall 111 and side walls 112. One end of the side wall 112 is connected to the bottom wall 111, and the other end extends away from the bottom wall 111, and both define a housing chamber 101 together. The lid 120 is attached to one end of the side wall 112 away from the bottom wall 111 and covers the housing chamber 101. The direction in which the bottom wall 111 faces the lid 120 is the first direction Z. The electrode assembly 200 is housed in the housing chamber 101 and includes a first electrode sheet 210, a second electrode sheet 220, and a separator 230. The first electrode sheet 210 includes a first electrode sheet unit 211, and the second electrode sheet 220 includes a second electrode sheet unit 221. The first electrode sheet unit 211 and the second electrode sheet unit 221 are stacked along the illustrated second direction X, and both are provided perpendicular to the second direction X. A separator 230 is provided between the adjacent first electrode sheet unit 211 and second electrode sheet unit 221.

[0043] Note that the "first direction" described in the specification of this application means the direction in which the case 110 faces the lid 120, that is, the packaging direction of both. In this embodiment, this first direction is the thickness direction of the electrochemical device 1. The "second direction" described in the specification of this application is a direction perpendicular to the above first direction Z. In this embodiment, this second direction X is the width direction of the electrochemical device 1. In other embodiments of this application, it is understood that the second direction X may be the length direction of this electrochemical device 1. Further, hereinafter, for the convenience of explanation and understanding, a direction perpendicular to the above first direction Z and second direction X is defined as the third direction Y. Next, taking the case where this electrochemical device 1 is a hard shell lithium ion battery as an example, the case assembly 100 and the electrode assembly 200 will be described in detail in order. However, in other embodiments of this application, it should be understood that this electrochemical device 1 may be other forms of batteries such as soft pack batteries or sodium ion batteries.

[0044] Referring to FIGS. 1 and 2, the case assembly 100 is a container and mounting base for other elements in the electrochemical device 1. This case assembly 100 includes a case 110 and a lid 120. Here, the case 110 is a box-shaped structure including a bottom wall 111 and side walls 112. The bottom wall 111 is a flat plate-like structure. The side walls 112 are substantially annular structures forming a closed cross-section, one end of which is connected to the bottom wall 111 and the other end extends away from the bottom wall 111. This bottom wall 111, together with the side walls 112, defines the accommodation chamber 101 for accommodating the electrode assembly 200, the electrolyte, etc. Optionally, when viewed along the first direction Z, the side walls 112 form a substantially rectangular or rounded rectangular shape. The side walls 112 include a first side wall unit 1121 and a second side wall unit 1122 oppositely arranged along the third direction Y, and a third side wall unit 1123 and a fourth side wall unit 1124 oppositely arranged along the second direction X. The lid 120 is similarly a flat plate-like structure and is oppositely arranged with the bottom wall 111 along the first direction Z. This lid 120 is attached to one end of the side walls 112 away from the bottom wall 111 and covers the accommodation chamber 101.

[0045] In this embodiment, the bottom wall 111 and the integrally formed side wall 112 may be formed separately. The bottom wall 111 is fixed to the side wall 112 by welding such as laser welding, for example, and covers one end of the side wall 112 facing the bottom wall 111. The lid 120 is fixed to the integrally formed side wall 112 by welding such as laser welding, for example, and covers one end of the side wall 112 facing the lid 120. Preferably, when viewed along the first direction X, the edge of the bottom wall 111 does not exceed the end of the side wall 112 close to the bottom wall 111, and the edge of the lid 120 does not exceed the end of the side wall 112 close to the lid 120, so that under the condition that the case assembly 100 provides a storage chamber 101 with a sufficient volume, the overall volume of the electrochemical device 1 or the volume occupied when the electrochemical device 1 is incorporated into a power consumption device can be made as small as possible. Of course, in other embodiments of the present application, only the edges of the bottom wall 111 or the lid 120 may be set not to exceed the edges of the side wall 112. It should also be noted that in other embodiments, the bottom wall 111 and the side wall 112 may be integrally formed by a conventional method such as integral stamping.

[0046] When considering the case where the temperature of the electrochemical device 1 is too high or there are other side reactions, the gas generation within the case assembly 100 may cause the air pressure to rise, potentially leading to an explosion of the electrochemical device 1, presenting a high safety risk. In this embodiment, in order to reduce such risks, in this electrochemical device 1, a pressure relief portion 130 is installed in the case assembly 100. When the air pressure within the electrochemical device 1 is higher than a preset threshold value, the pressure relief portion 130 communicates the accommodation chamber 101 with the outside air of the case assembly 100 and further discharges the gas within the accommodation chamber 101 to the outside to eliminate the above-mentioned risks. Here, the "preset threshold value" described in the specification of the present application is the internal pressure value of the electrochemical device 1 when the pressure relief portion 130 is switched to a state where it appropriately communicates the accommodation chamber 101 with the outside air of the case assembly 100. This preset threshold value is higher than the normal internal air pressure of the electrochemical device 1 and lower than the pressure value of the internal air pressure before the electrochemical device 1 explodes in the case where there is no pressure relief portion. Regarding the structure of the pressure relief portion 130, there are actually various structures. For example, in some embodiments, the pressure relief portion 130 is a region with lower strength than other parts of the case assembly 100. Specifically, the pressure relief portion 130 may be a region with a smaller thickness than other parts. When the air pressure within the accommodation chamber 101 becomes higher than the above-mentioned preset threshold value, first, the pressure relief portion 130 is breached to perform pressure relief. For example, in another embodiment, the pressure relief portion 130 is a minute valve element. Specifically, the case assembly 100 is provided with a penetrating pressure relief hole, and the pressure relief portion 130 is provided in this pressure relief hole. When the air pressure within the accommodation chamber 101 is lower than the preset threshold value, the pressure relief portion 130 covers this pressure relief hole. On the other hand, when the air pressure within the accommodation chamber 101 is higher than the preset threshold value, the pressure relief portion 130 opens this pressure relief hole to perform pressure relief.

[0047] Regarding the above-described electrode assembly 200, reference is made to FIG. 3, and FIGS. 1 and 2 are combined for description. This electrode assembly 200 is a core element in the electrochemical device 1, and the electrochemical device 1 is charged and discharged by the electrode assembly 200. Specifically, the electrode assembly 200 includes a first electrode sheet 210, a second electrode sheet 220, and a separator 230. The first electrode sheet 210, the second electrode sheet 220, and the separator 230 are sequentially stacked and provided along the illustrated second direction X. The polarities of the first electrode sheet 210 and the second electrode sheet 220 are opposite, and a separator 230 is provided between the adjacent first electrode sheet 210 and the second electrode sheet 220. In this embodiment, the electrode assembly 200 includes a plurality of first electrode sheets 210, a plurality of second electrode sheets 220, and a plurality of separators 230. Each first electrode sheet 210 and each second electrode sheet 220 are alternately provided along the second direction X, and a separator 230 is provided between the adjacent first electrode sheet 210 and the second electrode sheet 220. Here, "a plurality" described in the specification of the present application means two or more.

[0048] Specifically, referring to FIGS. 4 to 7, FIGS. 4 to 7 show a front view and a bottom view of the first electrode sheet 210, and a front view and a plan view of the second electrode sheet 220, respectively. Referring to other drawings as well, the first electrode sheet 210 includes a first electrode sheet unit 211, and this first electrode sheet unit 211 is the main body of the first electrode sheet 210. The second electrode sheet 220 includes a second electrode sheet unit 221, and this second electrode sheet unit 221 is the main body of the second electrode sheet 220. The polarities of the first electrode sheet unit 211 and the second electrode sheet unit 221 are opposite. The first electrode sheet unit 211 of each first electrode sheet 210 and the second electrode sheet unit 221 of each second electrode sheet 220 are stacked and provided along the second direction X, and a separator 230 for separation is provided between the adjacent first electrode sheet unit 211 and the second electrode sheet unit 221.

[0049] Next, taking the case where the first electrode sheet 210 is the anode sheet and the second electrode sheet 220 is the cathode sheet as an example, the structures of the first electrode sheet 210 and the second electrode sheet 220 will be described in order. Specifically, referring to FIGS. 4 and 5, the first electrode sheet 210 includes a first current collector 212 and a first active material layer 213. The first current collector 212 is a sheet-like structure including a first region 2121 and a second region 2122. The first region 2121 is rectangular as a whole and is provided perpendicular to the second direction X. The second region 2122 is elongated and is electrically connected to the first region 2121. In the present embodiment, the second region 2122 is integrally formed with the first region 2121 and is formed to extend outward from the edge of the first region 2121. Of course, in other embodiments of the present application, the second region 2122 may be formed separately from the first region 2121 and may be electrically connected to the first region 2121 by welding or adhesion. This first current collector 212 is a base material that supports the first active material layer 213 and is also a carrier for electron transfer by the first electrode sheet 210. In some embodiments, the first current collector 212 is a copper foil. Of course, in other embodiments of the present application, the first current collector 212 may be other suitable foil materials such as nickel foil. The first active material layer 213 is provided on the surface of the first region 2121 and constitutes the first electrode sheet unit 211 together with the first region 2121. In the present embodiment, the first active material layer 213 is a silicon-based negative electrode active material. For example, the first active material includes one or more of silicon, silicon-based oxides, silicon carbide, silicon nanowires, and silicon nanoparticles. Of course, in other embodiments of the present application, as long as it can be ensured that the first active material contains silicon element, other types of silicon-based materials may be included. The silicon-based negative electrode active material has the advantages of high gram capacity and low potential compared with the carbon-based negative electrode active material. Therefore, this arrangement helps to increase the energy density of the electrochemical device 1. Preferably, the percentage of the mass of silicon element in the first active material layer 213 with respect to the total mass of the first active material layer 213 is 10% or more. More preferably, the percentage of the mass of silicon element in the first active material layer 213 with respect to the total mass of the first active material layer 213 is 30% or more and 80% or less.When the electrochemical device 1 is charged, since the expansion rate of the silicon-based negative electrode material is high, the above setting aims to ensure that the electrochemical device 1 has a high energy density and to avoid excessive expansion of the electrode assembly 200 during charging. In this electrode assembly 200, each first electrode sheet unit 211 is provided at intervals along the second direction X, and each second region 2122 extends outside the separator 230 and is electrically connected, whereby the first electrode sheets 210 are electrically connected to each other.

[0050] Specifically, referring to FIGS. 6 and 7, the second electrode sheet 220 includes a second current collector 222 and a second active material layer 223. The second current collector 222 is a sheet-like structure including a third region 2221 and a fourth region 2222. The third region 2221 is generally rectangular and is provided perpendicular to the second direction X. The fourth region 2222 is elongated and is electrically connected to the third region 2221. In the present embodiment, the fourth region 2222 is integrally formed with the third region 2221 and extends outward from the edge of the third region 2221. Of course, in other embodiments of the present application, the fourth region 2222 may be formed separately from the third region 2221 and may be electrically connected to the third region 2221 by welding or adhesion. The second current collector 222 is a base material that supports the second active material layer 223 and is also a carrier for electron transfer by the second electrode sheet 220. In some embodiments, the second current collector 222 is an aluminum foil. Of course, in other embodiments of the present application, the second current collector 222 may be another suitable foil material such as a nickel foil. The second active material layer 223 is a carrier for occluding or desorbing lithium ions. The second active material layer 223 is provided on the surface of the third region 2221 and constitutes the second electrode sheet unit 221 together with the third region 2221. In this electrode assembly 200, each second electrode sheet unit 221 is provided at intervals along the second direction X, and is provided alternately with each first electrode sheet unit 211. Each fourth region 2222 extends outside the separator 230 and is electrically connected, whereby the second electrode sheets 220 are electrically connected to each other. In the present embodiment, the second active material layer 223 is a positive electrode active material containing a lithium-based compound.

[0051] The separator 230 is provided between the adjacent first electrode sheet unit 211 and the second electrode sheet unit 221, and mainly serves to separate the first electrode sheet 210 and the second electrode sheet 220 and conduct ions, but its material is not limited. In some embodiments, the separator 230 includes a porous substrate. In some embodiments, the separator 230 further includes a functional coating layer disposed on the porous substrate, and the functional coating layer may include at least one of a binder or inorganic particles. In some embodiments, the porous substrate is a polymer film, a multilayer polymer film, or a non-woven fabric made of any one type of polymer selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyphthaloyldiamine, polyester, polyacetal, polyamide, polycarbonate, polyimide, polyether ether ketone, polyaryl ether ketone, polyether imide, polyamide imide, polybenzimidazole, polyether sulfone, polyphenylene ether, cycloolefin copolymer, polyphenylene sulfide, and polyethylene naphthalene, or a polymer mixture of two or more types. Such polymers have high thermal stability and facilitate coating by enabling easy surface treatment. Also, such polymers are tough and easy to bend.In some embodiments, the binder includes at least one of a copolymer of vinylidene fluoride - hexafluoropropylene, a copolymer of vinylidene fluoride - trichloroethylene, a polyacrylate ester, polyacrylic acid, a polyacrylate salt, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, a copolymer of ethylene - vinyl acetate, polyimide, polyoxyethylene, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl - branched starch, cyanoethyl - polyvinyl alcohol, cyanoethyl - cellulose, cyanoethyl - sucrose, amylopectin, sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, a copolymer of acrylonitrile - styrene - butadiene, polyvinyl alcohol, polyvinyl ether, polytetrafluoroethylene, polyhexafluoropropylene, a copolymer of styrene - butadiene, and polyvinylidene fluoride. These polymers can produce a strong adhesive effect for adhering inorganic particles or adhering and integrating the separator 230 with the first electrode sheet 210 / the second electrode sheet 220, and can increase the hardness of the electrode assembly 200. In other embodiments, the binder may include other polymers. In some embodiments, the inorganic particles include at least one of silica, alumina, titanium oxide, zinc oxide, magnesium oxide, hafnium dioxide, tin oxide, zirconium dioxide, yttrium oxide, silicon carbide, boehmite, magnesium hydroxide, aluminum hydroxide, calcium titanate, barium titanate, lithium phosphate, lithium titanium phosphate, and lanthanum titanate lithium titanate. All of these inorganic particles have high thermal stability and can improve the high - temperature resistance characteristics of the electrochemical device 1.

[0052] In some embodiments, before attaching the first electrode sheet unit 211, the second electrode sheet unit 221, and the separator 230 to the case assembly 100, the electrochemical device 1 further includes a first insulating tape 240 in order to be able to maintain a relatively stable laminated state without collapsing. Specifically, referring to FIG. 2, the electrode assembly 200 has a first surface 201 and a second surface 202 that face each other along the second direction X. The first insulating tape 240 is in a tensioned state, one end of which is fixed to the first surface 201, and the other end extends along the second direction X to the second surface 202 and is fixed to the second surface 202. In this way, by sandwiching the electrode assembly 200 between its two ends, the first insulating tape 240 can reduce the risk of slack deformation between the first electrode sheet unit 211 and the second electrode sheet 220 and the separator 230. Optionally, two first insulating tapes 240 are connected to the electrode assembly 200. The two first insulating tapes 240 are arranged opposite to each other along the first direction Z. One first insulating tape 240 is located between the electrode assembly 200 and the bottom wall 111, and the other first insulating tape 240 is located between the electrode assembly 200 and the lid 120.

[0053] In some embodiments, to fix the electrode assembly 200 to the inner wall of the case assembly 100, the electrochemical device 1 further includes a second insulating tape 250. This second insulating tape 250 is fixed to the electrode assembly 200 and the case assembly 100 respectively so as to fix the electrode assembly 200 to the case assembly 100. Specifically, continuing to refer to FIG. 2, the second insulating tape 250 is elongate and is located between the electrode assembly 200 and the side wall 112. One end of this second insulating tape 250 is fixed to the first surface 201, and the other end extends along the second direction X to the second surface 202 and is fixed to the second surface 202. The second insulating tape 250 is a double-sided tape, one side of which is adhesively fixed to the electrode assembly 200 and the other side of which is adhesively fixed to the side wall 112, thereby fixing the electrode assembly 200 and the case assembly 100. The second insulating tape 250 is intended to fix the electrode assembly 200 and the case assembly 100. Therefore, in other embodiments of the present application, it is understood that the second insulating tape 250 may be other types of insulating tapes such as hot melt adhesives and single-sided adhesive tapes, but is not particularly limited in the present application. At the same time, in other embodiments, as long as the second insulating tape can perform the function of fixing the electrode assembly to the case assembly, it may be located only between any surface of the electrode assembly and any surface of the case assembly.

[0054] In this embodiment, the case assembly 100 has conductivity, and this electrochemical device 1 further includes a first conductive member 300. Each of the second regions 2122 is electrically connected by this first conductive member 300, and this first conductive member 300 is electrically connected to the case assembly 100. Thereby, the case assembly 100 is configured as one conductive terminal in this electrochemical device 1. Specifically, referring to FIGS. 3 and 2, the second region 2122 is located between the first region 2121 and the first side wall unit 1121, has a bent shape, and includes a first portion 2123 and a second portion 2124. One end of the first portion 2123 is connected to the first region 2121, and the other end extends close to the first side wall unit 1121. The second portion 2124 is connected to one end of the first portion 2123 that is away from the first region 2121, is provided by being bent with respect to the first portion 2123, and the bending directions of each second portion are the same. The first conductive member 300 is in a sheet shape or a long shape and is provided between the electrode assembly 200 and the first side wall unit 1121. The second portion 2124 is electrically connected to the first conductive member 300. In this embodiment, the second regions 2122 are provided so as to overlap in order. Specifically, the electrode assembly 200 includes three or more first electrode sheets 210. Along the first predetermined direction M shown in FIG. 3, between any two adjacent second portions 2124, at least a part of the second portion 2124 located on the downstream side is laminated on the surface of the second portion 2124 located on the upstream side. Between any three adjacent second portions, the region where the middle second portion 2124 covers the second portion 2124 located on the upstream side is not covered by the second portion 2124 located on the downstream side. That is, there is no common lamination region between three adjacent second portions 2124. Here, the first predetermined direction M is a direction from one end of the second portion 2124 close to the first portion 2123 toward the end away from the first portion 2123. In this embodiment, the first predetermined direction M is parallel to the second direction X. Of course, in other embodiments of the present application, this first predetermined direction M may form a certain angle with respect to the second direction X.In other embodiments of the present application, each of the above second portions 2124 may be provided by being sequentially stacked along the third direction Y. However, in such an installation form, it is necessary to reserve a large space in advance between the above first region 2121 and the first side wall unit 1121. In contrast, in the present embodiment, the form in which each second portion 2124 is provided by being sequentially overlapped can solve the above deficiency.

[0055] The electrochemical device 1 further includes a second conductive member 400 and a pole 500. Each of the fourth regions 2222 is electrically connected by the second conductive member 400, and the second conductive member is connected to the pole 500. One end of the pole 500 is located in the accommodation chamber 101 and is connected to the second conductive member 400, that is, electrically connected to the fourth region 2222, and the other end protrudes from the case assembly 100. Thereby, the pole 500 is configured as the other conductive terminal of the electrochemical device 1. Continuing to refer to FIGS. 3 and 2, the fourth region 2222 is located between the third region 2221 and the second side wall unit 1122, has a bent shape, and includes a third portion 2223 and a fourth portion 2224. One end of the third portion 2223 is connected to the third region 2221, and the other end extends close to the second side wall unit 1122. The fourth portion 2224 is connected to one end of the third portion 2223 that is away from the third region 2221, is provided to be bent with respect to the third portion 2223, and the bending directions of the respective fourth portions 2224 are the same. The second conductive member 400 is in a sheet shape and is provided between the electrode assembly 200 and the second side wall unit 1122. By laminating the fourth portion 2224 on the surface of the first conductive member 300, each fourth region 2222 is electrically connected by the first conductive member 300. In the present embodiment, the fourth regions 2222 are provided to overlap in order. Specifically, along the second predetermined direction N shown in FIG. 3, between any two adjacent fourth portions 2224, at least a part of the fourth portion 2224 located on the downstream side is laminated on the surface of the fourth portion 2224 located on the upstream side. Between any three adjacent fourth portions 2224, the region where the middle fourth portion 2224 covers the second portion located on its upstream side is not covered by the second portion located on its downstream side. That is, there is no common lamination region between three adjacent fourth portions 2224. Here, the second predetermined direction N is a direction from one end of the fourth portion 2224 close to the third portion 2223 toward the end away from the third portion 2223. In the present embodiment, the second predetermined direction N is the same as the first predetermined direction M.Of course, in other embodiments of the present application, the second predetermined direction N may be opposite to the first predetermined direction M, or may form a certain angle with respect to the second direction Y.

[0056] It should be understood that in the present embodiment, the second region 2122 and the fourth region 2222 are respectively provided on one side of the first region 2121, but the present application is not limited thereto. In other embodiments of the present application, the second region 2122 and the fourth region 2222 may be located on the same side of the first region 2121. Correspondingly, the widths of the second region 2122 and the fourth region 2222 are both less than half of the width of the first region 2121.

[0057] In some embodiments, a liquid injection hole 102 communicating with the accommodation chamber 101 is provided on the outer surface of the case assembly 100, and this liquid injection hole 102 is for supplying electrolyte to the accommodation chamber. Correspondingly, the electrochemical device 1 further includes a liquid injection plug (not shown), and this liquid injection plug is attached to the liquid injection hole and covers the liquid injection hole. Optionally, this liquid injection hole 102 is provided on the lid 120. Thereby, when injecting the electrolyte into the accommodation chamber 101, the electrolyte can penetrate into the gap between the first electrode sheet unit 211, the separator 230, and the second electrode sheet unit 221 from the beginning, thereby increasing the penetration rate of the electrode assembly 200, and further shortening the manufacturing cycle of the electrochemical device 1 to a certain extent. Further, optionally, the liquid injection hole 102 is provided close to the geometric center of the lid 120. For example, the distance between the two is less than 5 mm. Of course, in other embodiments of the present application, the liquid injection hole 102 may be provided on the bottom wall 111. By such an installation, the penetration rate of the electrode assembly 200 can be increased in the same manner. Correspondingly, the liquid injection hole 102 may be provided close to the geometric center of the bottom wall 111. For example, the distance between the two is less than 5 mm.

[0058] Note that the above description has taken as an example that this electrochemical device 1 includes one electrode assembly 200, but it should be understood that the present application is not limited thereto. For example, in other embodiments of the present application, the electrochemical device 1 may include two or more electrode assemblies 200, each electrode assembly 200 is arranged along the second direction X, each electrode assembly 200 is connected to the same first conductive member 300, and each electrode assembly 200 is connected to the same second conductive member 400. As the electrical connection method between the electrode assemblies 200, series connection, parallel connection, or mixed connection may be used. Note that by laminating a plurality of electrode assemblies 200, it is possible to avoid the thickness of a single electrode assembly 200 being too thick, thereby making the lamination process of each electrode assembly 200 easier and reducing the error rate during the lamination of the electrode assembly 200.

[0059] In an electrochemical device in which a commercially available electrode assembly has a laminated structure, the lamination direction of the first electrode sheet and the second electrode sheet (i.e., the second direction X) coincides with the package direction of the case and the lid in the case assembly (i.e., the first direction Z). In this electrochemical device, during charging, the electrode assembly expands significantly along the lamination direction. At the same time, since the strength of the case assembly in the package direction is low, the expansion and deformation of the electrode assembly easily deform the case assembly in the lamination direction, further causing cracks, thereby causing phenomena such as electrolyte leakage and reducing the mountability of the electrochemical device.

[0060] The electrochemical device 1 according to an embodiment of the present application includes a case assembly 100 and an electrode assembly 200. The electrode assembly 200 includes a first electrode sheet 210, a second electrode sheet 220, and a separator 230. The first electrode sheet 210 includes a first electrode sheet unit 211, and the second electrode sheet 220 includes a second electrode sheet unit 221. The first electrode sheet unit 211 and each second electrode sheet unit 221 are stacked along a second direction Y perpendicular to the first direction X, and a separator 230 is provided between the adjacent first electrode sheet unit 211 and second electrode sheet unit 221. Therefore, in the process of charging the electrochemical device, the electrode assembly 200 mainly expands along the second direction Y, and the amount of expansion in the first direction Z is extremely small. Thus, the case assembly 100 is less likely to be deformed or cracked due to the expansion of the electrode assembly 200.

[0061] In summary, the electrochemical device 1 according to an embodiment of the present application can improve the current situation where the case assembly 100 of the current electrochemical device is likely to be deformed or cracked. Further, since the degree of expansion of the electrochemical device 1 in the first direction Z is small and thus expansion does not occur, this electrochemical device 1 does not need to provide a reserve space between the electrode assembly 200 and the case assembly 100 along the above direction within the case assembly 100. Therefore, the energy density of this electrochemical device can be further increased. That is, the electrochemical device 1 according to an embodiment of the present application can improve the current situation where it is likely to expand and deform in the first direction X while ensuring that the energy density is not substantially lost.

[0062] It should be noted that there seems to be a mistake in the original text where it mentions "the second direction X" which should probably be "the second direction Y" for the context to be consistent as the first direction is defined as X. The translation has been made accordingly.Next, taking the case where a negative electrode active material with a mass ratio of silicon element of 60% (hereinafter referred to as a high-silicon-based negative electrode active material) is used in the first active material layer 213 in this electrochemical device 1 as an example, a supplementary explanation will be given regarding the difference in energy density between the electrochemical device 1 according to the embodiment of the present application and a conventional electrochemical device in the related art. In the following example, the length of the case assembly 100 of each electrochemical device is 82.5 mm, the width is 72.5 mm, and the thickness is 50 mm, and the total gap on both sides between the case assembly 100 and the first electrode sheet unit 211 is calculated to be 2.5 mm.

[0063] First, an electrochemical device using a conventional graphite-based negative electrode active material and in which each element in the electrode assembly is stacked along the first direction Z is defined as the first electrochemical device. In the first electrochemical device, the case space is almost completely filled in the Z direction. An electrochemical device using a high-silicon-based negative electrode active material and in which each element in the electrode assembly is stacked along the first direction Z is defined as the second electrochemical device. Due to the expansion characteristics of the high-silicon-based negative electrode laminated cell, in order to prevent deformation and cracking of the case due to its expansion, this second electrochemical device needs to reserve approximately 10% of the thickness space along the first direction Z inside the case assembly in advance. An electrochemical device using a high-silicon-based negative electrode active material and in which each element in the electrode assembly is stacked along the second direction X is defined as the third electrochemical device.

[0064] Regarding the first electrochemical device and the second electrochemical device, since the high-silicon-based has advantages such as high gram capacity and low potential, although the second electrochemical device reserves an expansion space in advance, the energy density of the second electrochemical device is higher than that of the first electrochemical device, and the ratio of the energy densities of the two is S1, and S1 is about 1.3.

[0065] The electrode assembly in the second electrochemical device is stacked along the first direction Z and needs to reserve 10% of the space in the first direction Z in advance. Therefore, the effective dimensions of the electrode assembly in the second electrochemical device are a length of 80 mm, a width of 70 mm, and a thickness of 45 mm, and the volume of this second electrochemical device is Vb.

[0066] The electrode assembly in the third electrochemical device is stacked along the width direction of the electrochemical device, that is, the second direction X is the width direction of the electrochemical device. The effective dimensions of the electrode assembly in this third electrochemical device are 80 mm in length, 47.5 mm in width, and 72.5 mm in thickness, and the volume of this third electrochemical device is Vc. Therefore, the ratio of the energy density of the third electrochemical device to that of the second electrochemical device is S2 = Vc / Vb = 1.09325.

[0067] From the above data, it can be seen that the electrochemical device 1 according to the embodiment of the present application has an energy density increase of about (S1*S2 - 1)*100% = 42.12% compared to the conventional electrochemical devices currently on the market. That is, the electrochemical device according to the embodiment of the present application has an energy density increase of about 40% compared to the conventional electrochemical devices.

[0068] Based on the same concept, the present application further provides a power consumption device. Referring to FIG. 8, FIG. 8 is a schematic diagram of a power consumption device 2 according to an embodiment of the present application. This power consumption device 2 includes any one of the electrochemical devices (1, 1b) of the above embodiments and a load structure powered by this electrochemical device. In this embodiment, this power consumption device 2 includes a mobile phone. In other embodiments of the present application, the power consumption device may be other power-driven devices such as a tablet, a wristwatch, earphones, a personal computer, a drone, an electric vehicle, an electric bicycle, a power tool, and a cleaning robot.

[0069] Since this power consumption device 2 includes the electrochemical device 1 in the above embodiment, it is possible to improve the current situation where the electrochemical device in the current power consumption device 2 is prone to expand and deform in the first direction X.

[0070] Note that the above embodiments are for explaining the technical solutions of the present application and are not for limiting the present application. Based on the idea of the present application, the technical features in the above embodiments or different embodiments can be combined, the steps can also be realized in any order, and there are many other changes in different aspects of the present application as described above, but they will not be described in detail for the sake of simplicity. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can modify the technical solutions described in each of the foregoing embodiments or equivalently replace some of the technical features. These modifications or replacements do not deviate from the essence of the corresponding technical solutions from the scope of the technical solutions according to each embodiment of the present application.

Claims

1. An electrochemical device comprising a case assembly and an electrode assembly, wherein the case assembly includes a case and a lid, the case includes a bottom wall and side walls, one end of each side wall is connected to the bottom wall, the other end extends away from the bottom wall, the bottom wall and the side walls together define a housing chamber, the lid is attached to the end of the side wall that extends away from the bottom wall to cover the housing chamber, and the direction from the bottom wall towards the lid is defined as the first direction, the electrode assembly is housed in the housing chamber and includes a first electrode sheet, a second electrode sheet, and a separator, the first electrode sheet includes a first electrode sheet unit, the second electrode sheet includes a second electrode sheet unit, the first electrode sheet unit and the second electrode sheet unit are stacked along a second direction and are both provided perpendicular to the second direction, and the separator is provided between adjacent first electrode sheet units and second electrode sheet units, wherein the second direction is perpendicular to the first direction, characterized in that it is an electrochemical device.

2. The first electrode sheet is an anode sheet, the first electrode sheet includes a first current collector and a first active material layer provided on the surface of the first current collector, the material of the first active material layer contains silicon element, and the percentage of the mass of the silicon element in the total mass of the first active material layer is 10% or more, characterized in that it is the electrochemical device according to Claim 1.

3. The percentage of the mass of the silicon element in the total mass of the first active material layer is 30% or more and 80% or less, characterized in that it is the electrochemical device according to Claim 2.

4. The first active material layer includes at least one of silicon, silicon-based oxides, silicon carbide, silicon nanowires, and silicon nanoparticles, characterized in that it is the electrochemical device according to Claim 2.

5. Further comprising a first conductive member, the first electrode sheet includes a first current collector and a first active material layer, the first current collector includes a first region and a second region, the first region is provided perpendicular to the second direction, the second region is electrically connected to the first region, the first active material layer is provided on the surface of the first region, the first region and the first active material layer together constitute the first electrode sheet unit, each of the first electrode sheet units is provided at intervals along the second direction, and the second region is electrically connected to the first conductive member. The electrochemical device according to claim 1, characterized in that.

6. The case has a first side wall unit and a second side wall unit oppositely installed along a third direction, both the second region and the first conductive member are located between the first region and the first side wall unit, and the third direction is perpendicular to the first direction and the second direction respectively. The second region includes a first portion and a second portion. One end of the first portion is connected to the first region, and the other end extends close to the first side wall unit. The second portion is connected to one end of the first portion away from the first region and is provided by being bent with respect to the first portion. The second portion is connected to the first conductive member. The electrochemical device according to claim 5, characterized in that.

7. The electrode assembly includes three or more first electrode sheets, the second portion is provided by being bent with respect to the first portion, and the bending directions of each of the second portions are the same. Along a first predetermined direction, between any two adjacent second portions, at least a part of the second portion located on the downstream side is laminated on the surface of the second portion located on the upstream side, and there is no common lamination region between any three adjacent second portions. The first predetermined direction is a direction from one end of the second portion close to the first portion to the end away from the first portion. The electrochemical device according to claim 6, characterized in that.

8. Further comprising a first insulating tape. The electrode assembly has a first surface and a second surface facing each other along the second direction, one end of the first insulating tape is fixed to the first surface, and the other end is fixed to the second surface. The electrochemical device according to claim 1, characterized in that.

9. Further comprising a second insulating tape, wherein the second insulating tape is fixed to the electrode assembly and the case, respectively, so as to fix the electrode assembly to the case. The electrochemical device according to claim 1, characterized in that.

10. When viewed along the first direction, the edge of the bottom wall does not exceed the end of the side wall close to the bottom wall. When viewed along the first direction, the edge of the lid does not exceed the end of the side wall close to the lid. The electrochemical device according to claim 9, characterized in that.

11. The electrochemical device includes two or more of the electrode assemblies, and each of the electrode assemblies is arranged along the second direction. The electrochemical device according to claim 1, characterized in that.

12. Further comprising a pole attached to the case, the pole being insulated from the case, and the pole being electrically connected to the second electrode sheet unit. The electrochemical device according to claim 1, characterized in that.

13. A liquid injection hole is provided in the lid, and the distance between the liquid injection hole and the geometric center of the lid is less than 5 mm, or a liquid injection hole is provided in the bottom wall, and the distance between the liquid injection hole and the geometric center of the bottom wall is less than 5 mm. The electrochemical device according to claim 1, characterized in that.

14. The aspect ratios of the first electrode sheet and the second electrode sheet are both 3 to 20. The electrochemical device according to claim 1, characterized in that.

15. The side wall is integrally formed, and the tensile strength of the material of the side wall is 1000 MPa or more. The electrochemical device according to claim 1, characterized in that.

16. The side wall is formed by welding, and the welding strength of the welding portion is 1000 MPa or more. The electrochemical device according to claim 1, characterized in that.

17. A power consumption device, comprising the electrochemical device according to any one of claims 1 to 16, characterized in that.

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