Electrochemical and Electronic Devices

Abstract

The present application discloses an electrochemical device and an electronic device. The electrochemical device includes a housing, a first electrode assembly, a second electrode assembly, and N separators. Each separator is arranged along a first direction such that the N separators, together with the housing, define N+1 storage chambers arranged along the first direction. The N+1 storage chambers include a first and a second storage chamber adjacent to each other, where N≧2. The first electrode assembly is accommodated in the first storage chamber, and the second electrode assembly is accommodated in the second storage chamber. The second electrode assembly is away from a reference plane relative to the first electrode assembly. The reference plane is a plane that passes through the center of the electrochemical device along the first direction and is perpendicular to the first direction. In the present application, the volume V1 of the first storage chamber and the volume V2 of the second storage chamber satisfy 0.5%≦(V2-V1) / V1≦5%, thereby improving the safety performance of the electrochemical device.

Description

[Technical field]

[0001] This application relates to the field of electrochemistry, and in particular to electrochemical devices and electronic devices. [Background technology]

[0002] At present, batteries are widely used in electronic products such as drones, mobile phones, tablets, and laptops. In some application scenarios, a single battery cell cannot achieve the desired output power, so multiple battery cells are usually connected to each other in a series, parallel, or mixed arrangement, so that the multiple battery cells work together to achieve the desired power output. However, connecting multiple battery cells to a series, parallel, or mixed arrangement can improve the output, but the energy density of the entire battery pack is low. Therefore, a design of a same-bag series / parallel battery is proposed. The same-bag series / parallel battery includes a housing and multiple electrode assemblies installed in the same housing. The series-connected electrode assemblies need to be separated by a separator to avoid the decomposition of the electrolyte due to high voltage. The parallel-connected electrode assemblies can be separated by a separator to avoid interference with each other.

[0003] The inventors have found through research that for the same bag series / parallel battery, the battery is prone to swelling under high temperature conditions, thus reducing the safety performance of the battery. Summary of the Invention [Problem to be solved by the invention]

[0004] Therefore, the present invention provides an electrochemical device and an electronic device that can improve the safety performance of the electrochemical device. [Means for solving the problem]

[0005] In order to solve the above technical problem, a first aspect of the present application provides an electrochemical device including a housing, a first electrode assembly, a second electrode assembly, and N separators. Each separator is arranged along a first direction such that the N separators, together with the housing, define N+1 storage chambers arranged along the first direction. The N+1 storage chambers include a first and a second storage chamber adjacent to each other, where N≧2. The first electrode assembly is accommodated in the first storage chamber, and the second electrode assembly is accommodated in the second storage chamber. The second electrode assembly is spaced apart from a reference plane relative to the first electrode assembly. Here, the reference plane is a plane that passes through the center of the electrochemical device along the first direction and is perpendicular to the first direction. A volume V1 of the first storage chamber and a volume V2 of the second storage chamber satisfy 0.5%≦(V2-V1) / V1≦5%. The inventors of the present application have found through research that in the same bag series / parallel battery, the expansion of the first receiving chamber located inside presses the second receiving chamber located outside, so that the second receiving chamber has a risk of being over-expanded due to excessive internal pressure. According to the above scheme, on the one hand, (V2-V1) / V1≧0.5% makes the space of the second receiving chamber larger, so that the expansion occurring in the first receiving chamber located inside is effectively buffered by the larger second receiving chamber, and can prevent the occurrence of excessive expansion of the entire electrochemical device and failure of sealing caused by the internal pressure of the second receiving chamber being too large; on the other hand, (V2-V1) / V1≦5% prevents the internal pressure of the first receiving chamber inside from being too large due to the volume of the first receiving chamber inside being too small, so as to prevent the occurrence of local excessive expansion of the electrochemical device and failure of sealing of the first receiving chamber inside, and further improve the safety performance of the electrochemical device.

[0006] In some embodiments, 1.5%≦(V2-V1) / V1≦4%. This scheme allows the second containing chamber to have a relatively large buffer space, which can more effectively prevent the internal pressure of the second containing chamber from being too high, and improve the safety performance of the electrochemical device.

[0007] In some embodiments, the volume V1 of the first accommodating chamber, the volume V3 of the first electrode assembly, the volume V2 of the second accommodating chamber, and the volume V4 of the second electrode assembly satisfy the condition: [(V1-V3) / V3] / [(V2-V4) / V4]≦0.9. This scheme comprehensively considers the relative size of the space occupied by the electrode assembly in the accommodating chamber and the amount of excess space, so that the second accommodating chamber has a larger amount of excess space to buffer the expansion of the first accommodating chamber, thereby further improving the safety performance of the electrochemical device.

[0008] In some embodiments, the electrochemical device satisfies the condition of 2.5%≦(VI-V3) / V3≦5.5%. With this scheme, the first containing chamber itself has a suitable extra space to suppress its own expansion, thereby reducing the degree of extrusion into the second containing chamber and improving the safety performance of the electrochemical device.

[0009] In some embodiments, the electrochemical device satisfies the condition: 3%≦(V2-V4) / V4≦9%. In the above scheme, the second containing chamber has a large excess space to buffer the expansion of the first containing chamber, thereby preventing the excessive expansion of the entire electrochemical device, and improving the safety performance of the electrochemical device.

[0010] In some embodiments, the electrochemical device further includes a first electrode tab electrically connected to the first electrode assembly and a second electrode tab electrically connected to the second electrode assembly, both of which extend from a first side of the housing. A first plane divides the first containing chamber into a first space proximate the first side and a second space away from the first side, and in a plane perpendicular to the first direction, the first plane is projected as a first straight line along the first direction, and a side edge of the first electrode assembly proximate the first side is projected as a first line segment along the first direction, and the first straight line passes through the first line segment. The second plane divides the second containing chamber into a third space close to the first side and a fourth space away from the first side, and in a plane perpendicular to the first direction, the second plane is projected as a second straight line along the first direction, and the side edge close to the first side of the second electrode assembly is projected as a second line segment along the first direction, and the first straight line passes through the first line segment. The volume T1 of the first space and the volume T3 of the third space satisfy 5%≦(T3-T1) / T1≦25%. In this scheme, the head space in the containing chamber is easily expanded, and when 5%≦(T3-T1) / T1≦25%, the relatively large head space of the second containing chamber can provide a buffer for the expansion of the head of the first containing chamber, suppress the occurrence of excessive expansion of the head of the electrochemical device, and further improve the safety performance of the electrochemical device.

[0011] In some embodiments, the electrochemical device satisfies the condition: 10%≦(T3−T1) / T1≦15%. In this scheme, the head space of the second containment chamber can provide a better buffer for the head expansion of the first containment chamber, and prevent the occurrence of excessive head expansion of the electrochemical device.

[0012] In some embodiments, the electrochemical device satisfies the condition that the second plane is located on the opposite side of the first plane from the first side. In this scheme, the head space of the first containing chamber (the space located on the first side of the first electrode assembly) has a larger buffer space after the position of the head space is expanded, which can improve the safety performance of the electrochemical device.

[0013] In some embodiments, the N separators include a first separator disposed between the first storage chamber and the second storage chamber, the first separator being recessed toward the first storage chamber to form a recessed groove.

[0014] In some embodiments, the separator comprises a substrate layer and a packaging layer located on the substrate layer, and this scheme provides the separator with excellent barrier and packaging performance.

[0015] In some embodiments, the packaging layer comprises a first polymeric material.

[0016] In some embodiments, the material of the substrate layer includes at least one of a metallic material, a second polymeric material, or a carbon material.

[0017] In some embodiments, the first polymeric material comprises at least one of polypropylene, anhydride modified polypropylene, polyethylene, ethylene propylene copolymers, polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, polyamide, polyester, amorphous α-olefin copolymers, or derivatives of these materials.

[0018] In some embodiments, the metallic material includes at least one of Ni, Ti, Cu, Ag, Au, Pt, Fe, Co, Cr, W, Mo, Al, Mg, K, Na, Ca, Sr, Ba, Si, Ge, Sb, Pb, In, Zn, stainless steel (SUS), and compositions or alloys thereof.

[0019] In some embodiments, the second polymeric material comprises polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyether ether ketone, polyimide, polyamide, polyethylene glycol, polyamideimide, polycarbonate, cyclic polyolefin, polyphenylene sulfide, polyvinyl acetate, polytetrafluoroethylene, polymethylene naphthalene, polyvinylidene fluoride, polypropylene carbonate, poly(vinylidene fluoride-hexafluoropropylene), poly(vinylidene fluoride-co-chlorotrifluoroethylene), silicone, vinylon, polypropylene, anhydride modified polypropylene, polyethylene, ethylene propylene copolymer, polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, polyphenylene ether, polyester, polysulfone, amorphous α-olefin copolymer, or at least one derivative of these materials.

[0020] In some embodiments, the carbon material comprises at least one of carbon felt, carbon film, carbon black, acetylene black, fullerene, conductive graphite film, or graphene film.

[0021] A second aspect of the present application also provides an electronic device comprising any of the electrochemical devices described above.

[0022] In the electrochemical device provided in the present application, the second electrode assembly is farther from the reference plane than the first electrode assembly. In other words, the first electrode assembly is closer to the center position along the first direction of the electrochemical device than the second electrode assembly, and thus the first accommodation chamber is closer to the center position along the first direction of the electrochemical device than the second accommodation chamber. In addition, in the present application, the volume V1 of the first accommodation chamber and the volume V2 of the second accommodation chamber satisfy the condition of 0.5%≦(V2-V1) / V1≦5%. In other words, the second accommodation chamber is 0.5% to 5% larger than the first accommodation chamber. That is, the accommodation chamber closer to the outer side of the electrochemical device is 0.5% to 5% larger than the adjacent accommodation chamber closer to the inner side. On the other hand, the space of the second accommodation chamber is larger when (V2-V1) / V1≧0.5%. Therefore, the expansion generated in the first containing chamber is buffered by the second containing chamber, and the excessive expansion of the whole electrochemical device and the occurrence of sealing failure caused by the internal pressure of the second containing chamber being too large can be prevented. On the other hand, (V2-V1) / V1≦5% can prevent the internal pressure of the inner first containing chamber from becoming too large caused by the volume of the inner first containing chamber being too small, thereby preventing the occurrence of local excessive expansion of the electrochemical device and the occurrence of sealing failure of the inner first containing chamber, and further improving the safety performance of the electrochemical device.

[0023] In order to more clearly describe the technical aspects of the embodiments of the present application, the following briefly describes the drawings that need to be used in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can also obtain other drawings based on these drawings. [Brief description of the drawings]

[0024] [Figure 1] 1 is a perspective view of an electrochemical device provided in accordance with one embodiment of the present application. [Diagram 2] FIG. 2 is a schematic cutaway perspective view of an electrochemical device provided in accordance with an embodiment of the present application. [Diagram 3]2 is a schematic cross-sectional side view of an electrochemical device provided in accordance with one embodiment of the present application, in which the second plane and the first plane in the view overlap each other. [Figure 4] FIG. 4 is a partially enlarged schematic view of FIG. [Diagram 5] FIG. 2 is an exploded cutaway view of an electrochemical device provided in accordance with one embodiment of the present application. [Figure 6] FIG. 2 is a schematic side view of an electrochemical device provided in accordance with another embodiment of the present application after cutting; [Figure 7] FIG. 2 is a partial schematic diagram of a side view of a separator provided by one embodiment of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] In order to facilitate understanding of the present application, the present application will be described in more detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that when a component is described as being "fixed" to another component, it may be directly fixed to the other component, or there may be one or more intermediate parts between them. When a component is described as being "connected" to another component, it may be directly connected to the other component, or there may be one or more intermediate parts between them. The terms "vertical", "horizontal", "left", "right" and similar expressions used in this specification are used for explanatory purposes only.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art of the present application. The terms used in the present application are for describing particular embodiments only and are not intended to be limiting of the present application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated, listed items.

[0027] Through research, the inventors of the present application have discovered that in the same bag series / parallel battery, the expansion of the first storage chamber located on the inside presses the second storage chamber located on the outside, so that the second storage chamber is at risk of expanding too much due to excessive internal pressure.

[0028] 1 to 7, the present embodiment provides an electrochemical device capable of suppressing the occurrence of excessive expansion and improving the safety performance of the electrochemical device. Hereinafter, an electrochemical device 100 will be described as an example. The electrochemical device 100 includes a housing 110, a first electrode assembly 130, a second electrode assembly 140, and N separators 120, where N≧2. That is, N can be 2, 3, 4, 5, etc.

[0029] Each separator 120 is disposed along a first direction X. As shown in FIGS. 1 to 4, in some embodiments, the first direction X is the thickness direction of the electrochemical device 100. The N separators 120, in cooperation with the housing 110, define N+1 storage chambers arranged along the first direction X. For example, when the number N of separators 120 is 2, the number of storage chambers is 3. When the number of separators 120 is 3, the number of storage chambers is 4.

[0030] The N+1 accommodation chambers include a first accommodation chamber 170 and a second accommodation chamber 180 adjacent to each other. The first electrode assembly 130 is accommodated in the first accommodation chamber 170, and the second electrode assembly 140 is accommodated in the second accommodation chamber 180. An electrolyte is accommodated in both the first accommodation chamber 170 and the second accommodation chamber 180. Thus, both the first accommodation chamber 170 and the second accommodation chamber 180 form independent electrochemical units. The electrochemical device 100 may also include other electrode assemblies such that one electrode assembly is disposed in each accommodation chamber other than the first accommodation chamber 170 and the second accommodation chamber 180. In this embodiment, the electrochemical device 100 further includes a first electrode tab 131 and a second electrode tab 141. The two first electrode tabs 131 having different polarities are connected to the two current collectors having different polarities of the first electrode assembly 130 in one-to-one correspondence, and protrude from the housing 110 between the housing 110 and the separator 120. The two second electrode tabs 141 having different polarities are connected to the two current collectors having different polarities of the second electrode assembly 140 in one-to-one correspondence, and protrude from the housing 110 between the housing 110 and the separator 120.

[0031] In some embodiments, the second electrode assembly 140 is farther from the reference plane 160 than the first electrode assembly 130, where the reference plane 160 is a plane that passes through the center of the electrochemical device along the first direction X and is perpendicular to the first direction X. In other words, the first electrode assembly 130 is closer to the center of thickness along the first direction X of the electrochemical device 100 than the second electrode assembly 140.

[0032] In some embodiments, the volume V1 of the first containing chamber 170 and the volume V2 of the second containing chamber 180 satisfy V2>V1. In this case, since the space of the second containing chamber 180 far from the center of thickness along the first direction X of the electrochemical device 100 is larger, the expansion generated in the first containing chamber 170 located inside is effectively buffered by the larger second containing chamber 180, and the excessive expansion of the entire electrochemical device 100 and the occurrence of package failure due to the internal pressure of the second containing chamber 180 being too large can be suppressed. In some embodiments, the volume V1 of the first containing chamber 170 and the volume V2 of the second containing chamber 180 satisfy 0.5%≦(V2-V1) / V1≦5%. Exemplarily, (V2-V1) / V1 may be 0.5%, 1%, 2%, 3%, 4%, or 5%, etc. In other words, the second housing chamber 180 is 0.5 to 5% larger than the first housing chamber 170. That is, the housing chamber closer to the outer side of the electrochemical device 100 is 0.5 to 5% larger than the adjacent housing chamber closer to the inner side. In this case, (V2-V1) / V1≦5% can suppress the internal pressure of the inner first housing chamber 170 from becoming excessively large due to the volume of the inner first housing chamber 170 being too small, suppress the occurrence of local excessive expansion of the electrochemical device 100 and packaging defects of the inner first housing chamber 170, and further improve the safety performance of the electrochemical device 100. Here, the volume V1 of the first housing chamber 170 and the volume V2 of the second housing chamber 180 may be measured after disassembling the electrochemical device, or may be obtained by performing in-situ measurement using a 3D CT scanning technique.

[0033] The first storage chamber 170 and the second storage chamber 180 may be two adjacent storage chambers that are not equally distant from any two reference planes 160 in the housing 110. For example, when N is 4, there are five storage chambers in the housing 110. For convenience of explanation, a case will be described in which the thickness dimensions of each storage chamber along the first direction X are the same, and in this case, along the first direction X, each storage chamber is numbered in order as storage chamber No. 1, storage chamber No. 2, storage chamber No. 3, storage chamber No. 4, and storage chamber No. 5. Here, when the thickness dimensions of the storage chambers along the first direction X are the same, storage chamber No. 3 is closest to the thickness center of the electrochemical device 100 along the first direction X. The second storage chamber 180 can be storage chamber No. 1. In this case, the first storage chamber 170 is storage chamber No. 2. The second storage chamber 180 may be storage chamber No. 2, and in this case, the first storage chamber 170 is storage chamber No. 3. The second accommodation chamber 180 may be accommodation chamber No. 4, and in this case, the first accommodation chamber 170 is accommodation chamber No. 3. The second accommodation chamber 180 may be accommodation chamber No. 5, and in this case, the first accommodation chamber 170 is accommodation chamber No. 4. If the electrochemical device 100 has other numbers of accommodation chambers, the order is sequentially deduced.

[0034] In particular, in the electrochemical device 100, only two chambers, the first housing chamber 170 and the second housing chamber 180, may satisfy the spatial size relationship of 0.5%≦(V2-V1) / V1≦5%. All adjacent housing chambers may also satisfy the above relationship. For example, in the embodiment where N is 4, the space of the No. 1 housing chamber is 0.5% to 5% larger than the space of the No. 2 housing chamber, the space of the No. 2 housing chamber is 0.5% to 5% larger than the space of the No. 3 housing chamber, the space of the No. 4 housing chamber is 0.5% to 5% larger than the space of the No. 3 housing chamber, and the space of the No. 5 housing chamber is 0.5% to 5% larger than the space of the No. 4 housing chamber. If the number of housing chambers in the electrochemical device 100 is other than the above, the following can be simultaneously satisfied.

[0035] In some embodiments, 1.5%≦(V2-V1) / V1≦5%. Illustratively, (V2-V1) / V1 may be 1.5%, 2%, 2.5%, 3%, 4%, or 5%, etc. In this scheme, the second containing chamber 180 may have a relatively large buffer space, which may more effectively prevent the internal pressure of the second containing chamber 180 from becoming excessive, and improve the safety performance of the electrochemical device 100.

[0036] The inventors of the present application further found that better effects can be obtained by controlling the relative relationship between the remaining space in the first accommodation chamber 170 and the second accommodation chamber 180 and the space occupied by the electrode assembly. Thus, in some embodiments, the volume V1 of the first accommodation chamber 170, the volume V3 of the first electrode assembly 130, the volume V2 of the second accommodation chamber 180, and the volume V4 of the second electrode assembly 140 are configured to satisfy [(V1-V3) / V3] / [(V2-V4) / V4]≦0.9. Exemplarily, [(V1-V3) / V3] / [(V2-V4) / V4] may be 0.5, 0.6, 0.7, 0.8, or 0.9, for example. Here, (V1-V3) / V3 is the ratio of the remaining space in the first accommodating chamber 170 excluding the space occupied by the first electrode assembly 130 to the space occupied by the first electrode assembly 130. (V2-V4) / V4 is the ratio of the remaining space in the second accommodating chamber 180 excluding the space occupied by the second electrode assembly 140 to the space occupied by the second electrode assembly 140. In this embodiment, the second accommodating chamber 180 has a larger surplus space for buffering the expansion of the first accommodating chamber 170, and further, the relative size of the space occupied by the electrode assemblies and the surplus space are taken into consideration in a comprehensive manner so that the second accommodating chamber 180 has a larger surplus space for buffering the expansion of the first accommodating chamber 170 and the safety performance of the electrochemical device 100 can be improved by suppressing excessive expansion of the electrochemical device 100.

[0037] In some embodiments, the electrochemical device satisfies 2.5%≦(V1−V3) / V3≦5.5%. In this scheme, the first containing chamber 170 itself has an appropriate extra space to suppress its own expansion, thereby reducing the degree of extrusion to the second containing chamber 180, and improving the safety performance of the electrochemical device 100.

[0038] In some embodiments, the electrochemical device satisfies 3%≦(V2−V4) / V4≦9%. In this scheme, the second containing chamber 180 has a large excess space to buffer the expansion of the first containing chamber 170, and suppresses the excessive expansion of the entire electrochemical device 100, thereby improving the safety performance of the electrochemical device 100.

[0039] 3-4. In some embodiments, the electrochemical device further includes a first electrode tab 131 electrically connected to the first electrode assembly 130 and a second electrode tab 141 electrically connected to the second electrode assembly 140. The first electrode tab 131 and the second electrode tab 141 are both drawn out from a first side of the housing 110. The first electrode assembly 130 and the second electrode assembly 140 are connected in series or in parallel via the first electrode tab 131 and the second electrode tab 141.

[0040] The first plane 150 divides the first containing chamber 170 into a first space 171 close to the first side and a second space away from the first side. In a plane perpendicular to the first direction X, the first plane 150 is projected as a first straight line along the first direction X, and the side edge close to the first side of the first electrode assembly 130 is projected as a first line segment along the first direction X, and the first straight line passes through the first line segment. In other words, the first plane 150 is bonded to the first side-proximal end of the first electrode assembly 130. Specifically, when the first side-proximal end of the anode sheet of the first electrode assembly 130 covers the first side-proximal end of the cathode sheet, the first plane 150 and the first side-proximal end position of the anode sheet are bonded to each other. The first space 171 is a space located on a first side of the electrode assembly of the first containing chamber 170 .

[0041] The second plane divides the second containing chamber 180 into a third space 181 near the first side and a fourth space away from the first side. In a plane perpendicular to the first direction X, the second plane is projected as a second straight line along the first direction X, the side edge near the first side of the second electrode assembly 140 is projected as a second line segment along the first direction X, and the first straight line passes through the first line segment. In other words, the second plane is bonded to the end portion near the first side of the second electrode assembly 140. Specifically, when the end portion near the first side of the anode sheet of the second electrode assembly 140 covers the end portion near the first side of the cathode sheet, the second plane and the position of the end portion near the first side of the anode sheet are bonded to each other. The third space 181 is a space located on the first side of the electrode assembly of the second containing chamber 180.

[0042] Considering that the volume expansion in each storage chamber of the electrochemical device 100 is more likely to occur in the head space (i.e., the space near the tab of the electrode assembly, for example, the first space 171 or the third space 181 described above), in some embodiments, the volume T1 of the first space 171 and the volume T3 of the third space 181 are arranged to satisfy 5≦(T3-T1) / T1≦25%. For example, (T3-T1) / T1 may be 5%, 10%, 15%, 20% or 25%, etc. In this scheme, it is considered that the head space position in the storage chamber is more likely to expand. When 5%≦(T3-T1) / T1≦25%, the relatively large head space of the second storage chamber 180 can provide a buffer for the head expansion of the first storage chamber 170, suppress excessive head expansion of the electrochemical device 100, and further improve the safety performance of the electrochemical device 100. Preferably, 10%≦(T3−T1) / T1≦25%.

[0043] In some embodiments, the second plane is configured to be located on the opposite side to the first side of the first plane 150. After expansion occurs in the head space of the first containing chamber 170 (the space located on the first side of the first electrode assembly 130), it has a larger buffer space, which can improve the safety performance of the entire electrochemical device 100.

[0044] There are various methods for making the spatial volume of the first storage chamber 170 smaller than that of the second storage chamber 180. In one embodiment, the spatial volume of the first storage chamber 170 can be made smaller than that of the second storage chamber 180 by making the dimension of the first storage chamber 170 along the first direction X smaller than that of the second storage chamber 180 along the first direction X. In another embodiment, as shown in FIG. 4, the spatial volume of the first storage chamber 170 can be made smaller than that of the second storage chamber 180 by making the cross-sectional area of ​​the first storage chamber 170 parallel to the first direction X smaller than the cross-sectional area of ​​the second storage chamber 180 parallel to the first direction X. Specifically, the area of ​​the separator 120 recessed toward the second storage chamber 180 can be made smaller.

[0045] In yet another embodiment, as shown in FIG. 6, the N separators 120 include a first separator 121 disposed between the first receiving chamber 170 and the second receiving chamber 180. The first separator 121 is recessed toward the first receiving chamber 170 to form a recessed groove 122. The recessed groove 122 is press-formed by a pressing process. After pressing, the space in the first receiving chamber 170 is smaller and the space in the second receiving chamber 180 is larger, so that the spatial volume of the second receiving chamber 180 is larger than the spatial volume of the first receiving chamber 170. This processing process is low cost and simple to process. Similarly, one recessed groove 122 can be punched in each of all the separators 120 to adjust the volume ratio between adjacent receiving chambers.

[0046] The groove 122 may be provided at any position of the first separator 121. In one embodiment, as shown in FIG. 6, the groove 122 is provided in the first separator 121 to define the first space 171 and the third space 181. In other words, in a plane perpendicular to the first direction X, the projection of the groove 122 along the first direction X is located within the projection of the first space 171 or the third space 181 along the first direction X. When the groove 122 is provided at the above position, it is possible to easily accommodate the electrolyte, while preventing deformation due to extrusion by the first electrode assembly 130 or the second electrode assembly 140.

[0047] As shown in FIG. 7, in some embodiments, the separator 120 includes a base layer 123 and a package layer 124 located on the surface of the base layer 123. The package layer 124 is provided on both sides of the base layer 123. The package layer 124 includes a first polymer material. The material of the base layer 123 includes at least one of a metal material, a second polymer material, and a carbon material. The separator 120 may have electronic insulation properties or electronic conductivity. In some embodiments, the separator 120 has a thickness of 50 μm to 500 μm.

[0048] In some embodiments, the first polymeric material comprises at least one of polypropylene, anhydride modified polypropylene, polyethylene, ethylene propylene copolymers, polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, polyamide, polyester, amorphous α-olefin copolymers, or derivatives of these materials.

[0049] The N metal materials include at least one of Ti, Cu, Ag, Au, Pt, Fe, Co, Cr, W, Mo, Al, Mg, K, Na, Ca, Sr, Ba, Si, Ge, Sb, Pb, In, Zn, stainless steel (SUS), and compositions or alloys thereof.

[0050] The second polymeric material may include at least one of polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyether ether ketone, polyimide, polyamide, polyethylene glycol, polyamideimide, polycarbonate, cyclic polyolefin, polyphenylene sulfide, polyvinyl acetate, polytetrafluoroethylene, polymethylene naphthalene, polyvinylidene fluoride, polypropylene carbonate, poly(vinylidene fluoride-hexafluoropropylene), poly(vinylidene fluoride-co-trifluorochloroethylene), silicone, vinylon, polypropylene, acid anhydride modified polypropylene, polyethylene, ethylene propylene copolymer, polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, polyphenylene ether, polyester, polysulfone, amorphous α-olefin copolymer, or derivatives of these materials.

[0051] The carbon material may include at least one of carbon felt, carbon film, carbon black, acetylene black, fullerene, conductive graphite film, and graphene film.

[0052] The electrode assembly of the present application is not particularly limited, and any electrode assembly of the prior art can be used as long as the object of the present application can be achieved. For example, a stacked type electrode assembly or a rolled type electrode assembly can be used. The electrode assembly generally includes a positive electrode sheet, a negative electrode sheet, and a separator film.

[0053] The negative electrode sheet in the present application is not particularly limited as long as it can achieve the object of the present application. For example, the negative electrode sheet usually includes a negative electrode current collector and a negative electrode active material layer. However, the negative electrode current collector is not particularly limited, and any negative electrode current collector known in the art can be used. For example, the negative electrode current collector includes copper foil, aluminum foil, aluminum alloy foil, composite current collector, and the like. The negative electrode active material layer includes a negative electrode active material. The negative electrode active material is not particularly limited, and any negative electrode active material known in the art can be used. For example, the negative electrode active material can include at least one of artificial graphite, natural graphite, mesophase carbon microspheres, soft carbon, hard carbon, silicon, silicon carbon, lithium titanate, and the like.

[0054] The positive electrode sheet in the present application is not particularly limited as long as it can achieve the object of the present application. For example, the above-mentioned positive electrode sheet usually includes a positive electrode current collector and a positive electrode active material layer. However, the positive electrode current collector is not particularly limited and may be any positive electrode current collector known in the art, such as an aluminum foil, an aluminum alloy foil, or a composite current collector. The positive electrode active material layer includes a positive electrode active material. The positive electrode active material is not particularly limited and may be any positive electrode active material in the prior art. For example, the positive electrode active material may include at least one of nickel cobalt manganese oxide (NCM), nickel cobalt aluminum oxide (NCA), lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, or lithium iron manganese phosphate.

[0055] The electrolyte in the present application is not particularly limited, and any electrolyte known in the art may be used, for example, in a gel state, a solid state, or a liquid state. For example, the liquid electrolyte may include a lithium salt and a non-aqueous solvent.

[0056] The lithium salt is not particularly limited, and any lithium salt known in the art can be used as long as the object of the present application can be achieved. For example, the lithium salt can include at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium difluorophosphate (LiPO2F2), lithium ditrifluoromethanesulfonimide LiN(CF3SO2)2 (LiTFSI), lithium bis(fluorosulfonyl)imide Li(N(SO2F)2) (LiFSI), lithium bisoxalate borate LiB(C2O4)2 (LiBOB), or lithium difluorooxalate borate LiBF2(C2O4) (LiDFOB). For example, the lithium salt can be selected from LiPF6.

[0057] The non-aqueous solvent is not particularly limited as long as the object of the present application can be achieved. For example, the non-aqueous solvent may include at least one of a carbonate compound, a carboxylate compound, an ether compound, a nitrile compound, or another organic solvent.

[0058] For example, the carbonate compound may be diethyl carbonate (DEC), dimethyl carbonate (DMC), methyl ethyl carbonate (EMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl carbonate (EPC), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinyl ethylene carbonate (VEC), fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate (1,2-difluoroethylene carbonate), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinyl ethylene carbonate (VEC), fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate (1,2-difluoroethylene carbonate), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinyl ethylene carbonate (VEC), fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate (1,2-difluoroethylene carbonate), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinyl ethylene carbonate (VEC), fluoroethylene carbonate (VEC), ethylene carbonate ( ... The fluoroethylene carbonate may include at least one of ethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-difluoro-1-methylethylene carbonate, 1,1,2-trifluoro-2-methylethylene carbonate, and trifluoromethylethylene carbonate.

[0059] The separator film in the present application is not particularly limited. For example, the separator film may be a polymer or an inorganic material formed from a material stable to the electrolyte of the present application. The separator film should generally have ion conductivity and electronic insulation properties.

[0060] For example, the separator film may include a substrate layer and a surface treatment layer. The substrate layer may be a nonwoven fabric, film, or composite film having a porous structure. The material of the substrate layer may be at least one selected from polyethylene, polypropylene, polyethylene terephthalate, and polyimide. Optionally, a polypropylene porous film, a polyethylene porous film, a polypropylene nonwoven fabric, a polyethylene nonwoven fabric, or a polypropylene-polyethylene-polypropylene porous composite film may be used. In some cases, a surface treatment layer is provided on at least one surface of the substrate layer. The surface treatment layer may be a polymer layer or an inorganic layer, or may be a layer formed by mixing a polymer and an inorganic material.

[0061] For example, the inorganic layer includes inorganic particles and a binder. The inorganic particles are not particularly limited, and may be selected from at least one of alumina, silica, magnesia, titanium oxide, hafnium dioxide, tin oxide, ceria, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, and barium sulfate. The binder is not particularly limited, and may be selected from one or a combination of polyvinylidene fluoride, copolymers of vinylidene fluoride and hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, and polyhexafluoropropylene. The polymer layer includes a polymer. The polymeric material may include at least one of polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylates, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride, or poly(vinylidene fluoride-hexafluoropropylene).

[0062] A second aspect of the present application also provides an electronic device comprising an electrochemical apparatus according to any of the above embodiments.

[0063] Hereinafter, the embodiments of the present application will be described in more detail with reference to examples and comparative examples. Various tests and evaluations were performed by the following methods. In addition, "parts" and "%" are based on weight unless otherwise specified.

[0064] The manufacturing process of the lithium ion batteries in the examples and comparative examples is as follows.

[0065] [Example 1] (1) Manufacturing of positive electrode sheets Cathode active material Li(Ni) 0.5 Co 0.2 Mn 0.3)O2, conductive agent Super P, and binder polyvinylidene fluoride were mixed in a weight ratio of 96:2.2:1.8, N-methylpyrrolidone (NMP) was added, and the mixture was uniformly stirred under the action of a vacuum stirrer to obtain a positive electrode slurry. Here, the solid content of the positive electrode slurry was 72 wt%. Next, the positive electrode slurry was uniformly applied to the aluminum foil of the positive electrode current collector, and the aluminum foil after application was dried at 85°C, and then cold pressed, cut, and divided, and dried under vacuum conditions at 85°C for 4 hours to obtain a positive electrode sheet.

[0066] (2) Manufacturing of negative electrode sheets The negative electrode active material, artificial graphite, conductive agent Super P, thickener sodium carboxymethylcellulose (CMC), and binder styrene-butadiene rubber (SBR) were mixed in a weight ratio of 96:2:0.8:1.2, deionized water was added, and a negative electrode slurry was obtained under the action of a vacuum mixer. Here, the solid content of the negative electrode slurry was 54 wt%. The negative electrode slurry was uniformly applied to the copper foil of the negative electrode current collector, and the copper foil after application was dried at 85°C, and then cold pressed, cut, and divided, and dried under vacuum conditions at 120°C for 12 hours to obtain a negative electrode sheet.

[0067] (3) Preparation of electrolyte In a glove box with a dry argon atmosphere, organic solvents EC (ethylene carbonate), DEC (diethyl carbonate) and EMC (methyl ethyl carbonate) were mixed in a mass ratio of EC / DEC / EMC = 3 / 2 / 5, and then LiPF6 (lithium hexafluorophosphate) was added and dissolved in the organic solvent and mixed uniformly to obtain an electrolyte solution with a LiPF6 concentration of 1.15M.

[0068] (4) Manufacturing of separator films A polyethylene (PE) separator film with a thickness of 9 μm was selected, and a slurry containing PVDF and inorganic particles (Al2O3) was applied and dried to obtain the final separator film. The thickness of the coating layer was 3 μm, and the porosity of the separator film was 55%.

[0069] (5) Manufacturing of electrode assemblies The positive electrode sheet, the separator film and the negative electrode sheet are stacked in order, and the separator film is placed between the positive electrode sheet and the negative electrode sheet to play the role of isolation. Then, the electrode assembly is obtained by winding the stacked positive electrode sheet, and the electrode assembly is prepared after the tabs are welded.

[0070] (6) Separator manufacturing The sealing material PP in the package layer was uniformly dispersed in the dispersant NMP (N-methylpyrrolidone) to obtain a suspension of the package layer with a concentration of 45 wt%. Next, using an applicator, a package layer PP with a thickness of 40 μm was prepared on two surfaces of the base layer A1 with a thickness of 20 μm. After that, the dispersant NMP in the suspension of the package layer was dried at 130 ° C, and the manufacture of the separator was completed.

[0071] (7) Manufacture of lithium-ion batteries The pit-formed aluminum plastic film with a thickness of 90 μm is placed in an assembly jig with the pit surface facing up, and one electrode assembly A is placed in the pit, and then, based on the design of the volume difference between the receiving chambers on both sides, a separator with an appropriate dimple area and depth is placed on the electrode assembly A and external force is applied to compress it. The above assembly semi-finished product is placed in another assembly jig, and another electrode assembly B is placed on the separator, and then another pit-formed separator is placed on the electrode assembly B and external force is applied to compress it. Next, another electrode assembly C is placed on the separator, and another pit-formed aluminum plastic film with a thickness of 90 μm is coated on the electrode assembly C with the pit surface facing down, and then the two aluminum plastic films are heat-compressed together with the separator, so that the electrode assembly A, the electrode assembly B, and the electrode assembly C are separated by the separator, to obtain the electrode assembly after assembly.

[0072] The prepared electrolyte is injected into each of the housing chambers of the assembled electrode assemblies, and the electrode assemblies are connected in series through processes such as vacuum packaging, standing, chemical formation, shaping, and capacity testing to obtain the final lithium ion battery.

[0073] 21512 <Examples 2 to 15 and Comparative Examples 1 to 2> 11 Adjust the specific structural dimensions and parameters corresponding to the lithium ion battery according to Table 1. The rest are the same as in Example 1.

[0074] <High temperature storage stability test method> In an environment of 25±3℃, the lithium ion battery is charged at a constant current of 0.05C to a full charge design voltage of 4.3×nV (where N is the number of electrode assemblies), and then charged at a constant voltage of 4.3×nV to a cut-off current of 0.025C to fully charge the lithium ion battery, and the thickness of the lithium ion battery at that time is measured as H0. Next, the lithium ion battery is left in a thermostatic box at 60℃ for 24 hours, taken out and cooled to 25±3℃, and the maximum thickness of the lithium ion battery at that time is measured as H1, and the high temperature storage expansion rate is (H1-H0) / H0×100%. At the same time, the lithium ion battery package is observed to see if there is any leakage.

[0075] Table 1 shows the structural dimensional parameters and performance of the lithium ion batteries in each of the examples and comparative examples.

[0076] [Table 1]

[0077] From the comparison between Examples 1 to 15 and Comparative Examples 1 to 2 in Table 1, the lithium ion batteries in Examples 1 to 15 that satisfy 0.5%≦(V2-V1) / V1≦5% had a significantly reduced high-temperature storage expansion rate and better package stability. This is because, on the one hand, (V2-V1) / V1≧0.5% makes the space of the outer storage chamber larger, so that the expansion occurring in the inner storage chamber is effectively buffered by the larger outer storage chamber, suppressing the occurrence of excessive expansion of the entire lithium ion battery and sealing failure due to the inner pressure of the outer storage chamber being too large, and thus improving the safety performance of the lithium ion battery. On the other hand, (V2-V1) / V1≦5% can suppress the inner pressure of the inner storage chamber from becoming too large due to the volume of the inner storage chamber being too small, suppressing the occurrence of localized excessive expansion and leakage from the inner storage chamber, and further improving the safety performance of the lithium ion battery.

[0078] Furthermore, comparing Example 4 with Example 11, it can be seen that Example 4, which further satisfies [(V1-V3) / V3] / [(V2-V4) / V4]≦0.9, has a lower high-temperature storage expansion rate. This is because, taking into consideration the size of the space occupied by the electrode assembly in the accommodation chamber and the relative size of the excess space, the outer accommodation chamber has a larger excess space to buffer the expansion of the inner accommodation chamber, thereby further suppressing the high-temperature storage expansion of the lithium-ion battery.

[0079] In addition, by comparing Examples 1 to 9 with Examples 12 to 15, it can be seen that the examples that satisfy 10%≦(T3-T1) / T1≦15% have a lower high temperature storage expansion rate. This is because, considering that the head space position in the receiving chamber is more likely to expand, when 10%≦(T3-T1) / T1≦15%, the larger head space of the outer receiving chamber can provide a buffer for the head expansion of the inner receiving chamber, suppressing excessive expansion of the head of the lithium ion battery, thereby further reducing the high temperature storage expansion rate of the lithium ion battery.

[0080] In addition, although the specification and drawings of the present application show preferred embodiments of the present application, the present application is not limited to the embodiments described herein and can be realized in many different forms. These examples are not provided as additional limitations to the contents of the present application, but are provided for the purpose of making the disclosure of the present application more complete. In addition, various embodiments not listed above formed by subsequently combining the above technical features with each other should be considered as being within the scope described in the present specification. Furthermore, those skilled in the art can make improvements or replacements according to the above description. All of these improvements and replacements should fall within the scope of protection of the claims attached to this application.

Claims

1. 1. An electrochemical device comprising: Housing and N separators arranged along a first direction and disposed to define, together with the housing, N+1 receiving chambers arranged along the first direction; A first electrode assembly; a second electrode assembly, The N+1 storage chambers include a first storage chamber and a second storage chamber adjacent to each other, where N≧2; the first electrode assembly is contained in the first containment chamber; the second electrode assembly is contained in the second containment chamber; the second electrode assembly is spaced apart from a reference plane relative to the first electrode assembly; the reference plane is a plane that passes through a center of the electrochemical device along the first direction and is perpendicular to the first direction; The electrochemical device, wherein a volume V1 of the first storage chamber and a volume V2 of the second storage chamber satisfy 0.5%≦(V2−V1) / V1≦5%.

2. 2. The electrochemical device according to claim 1, wherein 1.5%≦(V2−V1) / V1≦4% is satisfied.

3. 2. The electrochemical device of claim 1, wherein a volume V1 of the first containing chamber, a volume V3 of the first electrode assembly, a volume V2 of the second containing chamber, and a volume V4 of the second electrode assembly satisfy [(V1-V3) / V3] / [(V2-V4) / V4]≦0.

9.

4. The electrochemical device satisfies at least one of the following conditions (a) to (b): The condition (a) is that 2.5%≦(VI−V3) / V3≦5.5%, 4. The electrochemical device according to claim 3, wherein the condition (b) satisfies 3%≦(V2−V4) / V4≦9%.

5. the electrochemical device further comprising a first electrode tab electrically connected to the first electrode assembly and a second electrode tab electrically connected to the second electrode assembly; the first electrode tab and the second electrode tab both extend from a first side of the housing; a first plane partitioning the first receiving chamber into a first space proximate the first side and a second space away from the first side; In a plane perpendicular to the first direction, the first plane is projected as a first straight line along the first direction; a side edge of the first electrode assembly close to the first side is projected as a first line segment along a first direction; the first straight line passes through the first line segment, the second plane divides the second receiving chamber into a third space proximate the first side and a fourth space away from the first side; In a plane perpendicular to the first direction, the second plane is projected as a second straight line along the first direction; a side edge of the second electrode assembly close to the first side is projected as a second line segment along a first direction; the first straight line passes through the first line segment, 2. The electrochemical device according to claim 1, wherein the volume T1 of the first space and the volume T3 of the third space satisfy 5%≦(T3−T1) / T1≦25%.

6. The electrochemical device satisfies at least one of the following conditions (c) to (d): The condition (c) is that 10%≦(T3−T1) / T1≦15% is satisfied.

6. The electrochemical device according to claim 5, wherein the condition (d) is that the second plane is located on the opposite side of the first plane from the first side.

7. The N separators include a first separator provided between the first storage chamber and the second storage chamber, 2. The electrochemical device according to claim 1, wherein the first separator is recessed toward the first containing chamber to form a recessed groove.

8. the separator includes a substrate layer including a metal, and a package layer located on a surface of the substrate layer and including a first polymeric material; 2. The electrochemical device according to claim 1, wherein the material of the substrate layer includes at least one of a metal material, a second polymer material, and a carbon material.

9. the first polymeric material includes at least one of polypropylene, acid anhydride-modified polypropylene, polyethylene, ethylene propylene copolymer, polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, polyamide, polyester, amorphous α-olefin copolymer, or derivatives of these substances; The metal material includes at least one of Ni, Ti, Cu, Ag, Au, Pt, Fe, Co, Cr, W, Mo, Al, Mg, K, Na, Ca, Sr, Ba, Si, Ge, Sb, Pb, In, Zn, stainless steel (SUS), and compositions or alloys thereof; The second polymeric material includes at least one of polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyether ether ketone, polyimide, polyamide, polyethylene glycol, polyamideimide, polycarbonate, cyclic polyolefin, polyphenylene sulfide, polyvinyl acetate, polytetrafluoroethylene, polymethylene naphthalene, polyvinylidene fluoride, polypropylene carbonate, poly(vinylidene fluoride-hexafluoropropylene), poly(vinylidene fluoride-co-chlorotrifluoroethylene), silicone, vinylon, polypropylene, acid anhydride modified polypropylene, polyethylene, ethylene propylene copolymer, polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, polyphenylene ether, polyester, polysulfone, amorphous α-olefin copolymer, or derivatives of these substances; 9. The electrochemical device according to claim 8, wherein the carbon material includes at least one of carbon felt, carbon film, carbon black, acetylene black, fullerene, conductive graphite film, and graphene film.

10. An electronic device comprising the electrochemical device according to any one of claims 1 to 9.

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