Electrochemical device and electronic device including the same

Abstract

The present application provides an electrochemical device and an electronic device including the electrochemical device, wherein the electrochemical device comprises a packaging shell, a separator and electrode assemblies respectively arranged on both sides of the separator, each electrode assembly is provided with a pole ear, the packaging shell is respectively provided with a first recess and a second recess on both sides of the separator, a side wall of the first recess and a side wall of the second recess are integrally formed to form a first end face of the packaging shell, the packaging shell also comprises a second end face arranged opposite to the first end face and two side faces arranged opposite to each other and connected between the first end face and the second end face, the pole ear extends out of the second end face; the separator is sealed and connected to the first end face, the second end face and the two side faces, thereby dividing the space inside the packaging shell into two cavities, each cavity encapsulating an electrode assembly and an electrolyte. The electrochemical device and the electronic device have good energy density.

Description

Technical Field

[0001] The present application relates to the field of electrochemistry, and in particular to an electrochemical device and an electronic device comprising the electrochemical device. Background Art

[0002] With the development of science and technology, there is an increasing demand for the application of lithium-ion batteries in the fields of power tools and drones. These two major fields require batteries to have the function of instantaneous high-power discharge, while the traditional battery discharge voltage platform is only around 3.8V to 4.3V, which cannot meet their needs.

[0003] In order to increase the output voltage of lithium-ion batteries, the prior art generally connects different numbers of lithium-ion batteries in series through an external printed wiring substrate (PCB) to achieve a boosting function. However, this series connection method occupies volume space and causes a loss in energy density (ED). Summary of the invention

[0004] The present application provides an electrochemical device and an electronic device comprising the electrochemical device to improve the energy density thereof.

[0005] The first aspect of the present application provides an electrochemical device, comprising a packaging shell, a partition, and electrode assemblies respectively arranged on both sides of the partition. Each electrode assembly is provided with a pole ear. The packaging shell is provided with a first recess and a second recess on both sides of the partition, and a side wall of the first recess and a side wall of the second recess are integrally formed to form a first end face of the packaging shell. The packaging shell also includes a second end face arranged opposite to the first end face and two side faces arranged opposite to each other and connected between the first end face and the second end face. The pole ear extends out of the second end face. The partition is sealed and connected to the first end face, the second end face and the two side faces, thereby dividing the space inside the packaging shell into two cavities. Each cavity encapsulates an electrode assembly and an electrolyte.

[0006] The electrochemical device of the present application arranges a side wall of the first recess and a side wall of the second recess on the packaging shell to be integrally formed as the first end face of the packaging shell, and seals an edge of the partition with the first end face. Compared with the prior art, the edge of the partition does not need to be clamped between the upper and lower side walls of the first end face of the packaging shell, thereby reducing the risk of packaging failure of the electrochemical device and improving the safety performance of the electrochemical device. At the same time, the existence of the external folded edge of the first end face is avoided, reducing the loss of energy density caused by the external folded edge of the first end face, thereby effectively improving the energy density of the electrochemical device and significantly reducing the production cost of the electrochemical device.

[0007] In some embodiments of the present application, the separator includes a main body and a bent portion located at one edge of the main body. The bent portion extends into the first recess or the second recess and fits and is sealed with the first end face. The remaining edges of the main body are sealed with the second end face and the two side faces, respectively. Thus, the existence of the external folded edge of the first end face is avoided, thereby increasing the energy density of the electrochemical device and improving the packaging reliability of the electrochemical device.

[0008] In some embodiments of the present application, the electrochemical device further comprises a packaging material, which covers at least the periphery of two surfaces of the separator. By arranging the packaging material on the surface of the separator, the reliability of the sealed connection between the separator and the packaging shell is improved, thereby dividing the internal space of the packaging shell into two independent cavities.

[0009] In some embodiments of the present application, the electrochemical device further comprises a packaging material, and the packaging material covers the side of the bent portion facing the first end face. Thus, the bent portion can be sealed to the first end face, so that the partition is sealed to the packaging shell, thus avoiding the existence of an outer folded edge of the first end face.

[0010] In some embodiments of the present application, the edge of the main body and the edge of the bent portion form an angle area, and the packaging material also covers the angle area to ensure that the two cavities separated by the partition are also sealed and connected in the corner area, thereby achieving the effect of isolating the electrolytes in each cavity from each other to prevent leakage of the electrolyte from causing the electrolyte to decompose and fail during high-voltage charging.

[0011] In some embodiments of the present application, the packaging material includes at least one of polypropylene, anhydride-modified polypropylene, polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid copolymer, ethylene-vinyl alcohol copolymer, polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, epoxy resin, polyamide, polyester, amorphous α-olefin copolymer and derivatives thereof. The use of the above packaging materials can more effectively improve the sealing performance, thereby improving the packaging reliability of the electrochemical device.

[0012] In some embodiments of the present application, each electrode assembly is provided with pole tabs of different polarities, the pole tabs extend out of the packaging shell, and adjacent electrode assemblies are connected in series through the pole tabs.

[0013] In some embodiments of the present application, the separator has a thickness of 6 μm to 100 μm. When the separator has a thickness within the above range, the energy density and safety performance of the electrochemical device can be improved.

[0014] In some embodiments of the present application, the material of the separator includes at least one of a polymer film, a metal foil or a carbon material.

[0015] The second aspect of the present application provides an electronic device, comprising the electrochemical device provided in the first aspect of the present application. Therefore, the electronic device of the present application also has good energy density and safety performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application and the technical solutions of the prior art, the following briefly introduces the drawings required for use in the embodiments and the prior art. Obviously, the drawings described below are only some embodiments of the present application.

[0017] Figure 1 This is a schematic diagram of the internal structure of the packaging shell of an embodiment of the present application;

[0018] Figure 2 A schematic diagram of the structure of an electrochemical device according to an embodiment of the present application;

[0019] Figure 3 A schematic diagram of the exploded structure of an electrochemical device according to some embodiments of the present application;

[0020] Figure 4 Schematic diagram of the exploded structure of electrochemical devices in other embodiments of the present application;

[0021] Figure 5 Schematic diagram of the exploded structure of electrochemical devices in some other embodiments of the present application;

[0022] Figure 6 This is a schematic diagram of the planar structure of the partitions of some embodiments of the present application;

[0023] Figure 7 A schematic diagram of the three-dimensional structure of a partition in some embodiments of the present application;

[0024] Figure 8 Schematic diagram of the three-dimensional structure of the partition of other embodiments of the present application;

[0025] Fig. 9 Schematic diagrams of electrochemical device structures of other embodiments of the present application (a shows the AA direction, b shows the BB direction);

[0026] Fig.10 for Fig. 9 Schematic diagram of the cross-sectional structure of the electrochemical device along the AA direction;

[0027] Fig.11 for Fig. 9 Schematic diagram of the cross-sectional structure of the electrochemical device along the BB direction.

[0028] Figure numerals: 100. electrochemical device; 10. electrode assembly; 11. first electrode assembly; 12. second electrode assembly; 20. separator; 21. main body; 22. bending portion; 23. angle region; 24. side bending portion; 211. top edge; 40. packaging shell; 41. first recess; 42. second recess; 43. first end face; 44. second end face; 45. side face; 50. tab; 51. first positive electrode tab; 52. first negative electrode tab; 53. second positive electrode tab; 54. second negative electrode tab. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other technical solutions obtained by ordinary technicians in the field belong to the scope of protection of the present application.

[0030] It should be noted that in the specific implementation of the present application, lithium-ion batteries are used as an example of electrochemical devices to explain the present application, but the electrochemical devices of the present application are not limited to lithium-ion batteries. The specific technical solution is as follows:

[0031] like Figures 1 to 3 As shown, an embodiment of the first aspect of the present application provides an electrochemical device 100, including a packaging shell 40, a partition 20 and electrode assemblies 10 respectively arranged on both sides of the partition 20, each electrode assembly 10 is provided with a pole ear 50, and the packaging shell 40 is respectively provided with a first recess 41 and a second recess 42 on both sides of the partition 20, and a side wall of the first recess 41 and a side wall of the second recess 42 are integrally formed to form a first end face 43 of the packaging shell 40; the packaging shell 40 also includes a second end face 44 arranged opposite to the first end face 43 and two side faces 45 connected and arranged opposite to each other between the first end face 43 and the second end face 44, and the pole ear 50 extends from the second end face 44; the partition 20 is sealed and connected to the first end face 43, the second end face 44 and the two side faces 45, and the space inside the packaging shell 40 is divided into two cavities (not shown in the figure), and each cavity encapsulates an electrode assembly 10 and an electrolyte (not shown in the figure).

[0032] In the electrochemical device 100 of the present application, the packaging shell 40 is provided with a first recess 41 and a second recess 42 on both sides of the partition 20, and a side wall of the first recess 41 and a side wall of the second recess 42 are integrally formed to form a first end face 43, that is, the packaging shell 40 is integrally formed on this side of the first end face 43, and has no sealing edge and no external folding edge. And one edge of the partition 20 is sealed and connected to the first end face 43, and the above edge of the partition 20 can be sealed and connected to the packaging shell 40 without the existence of a sealing edge, the risk of packaging failure of the electrochemical device 100 is reduced, the safety performance of the electrochemical device 100 is improved, and the loss of energy density caused by the external folding edge of the first end face 43 is reduced, so that the energy density of the electrochemical device 100 can be effectively improved. At the same time, this design of the partition 20 and the packaging shell 40 greatly saves the manufacturing time and raw materials of the electrochemical device 100, and reduces the production cost of the electrochemical device 100. In addition, the partition 20 divides the space inside the packaging shell 40 into two cavities, each cavity encapsulates the electrode assembly 10 and the electrolyte, and ion insulation is achieved between the cavities to avoid the problem of internal short circuit of the electrochemical device 100 and the problem of electrolyte decomposition under high voltage, thereby improving the safety performance of the electrochemical device 100 and ensuring the effective power output of the electrochemical device 100.

[0033] In the present application, "first end face", "second end face" and "side face" all refer to the surface of the electrochemical device 100 in the length or width direction, rather than the surface of the electrochemical device 100 in the thickness direction. Among them, the "second end face" refers to the end face of the electrochemical device 100 extending from the electrode ear 50, including the top seal and the side wall of the packaging shell 40 connected to the top seal. After the electrochemical device 100 is packaged, the top seal can be folded to fit in the direction of the side wall of the packaging shell 40. "Two side faces" refer to the side faces of the electrochemical device 100 connected between the second end face 44 and the first end face 43. The two side faces are arranged opposite to each other in the length or width direction of the electrochemical device 100. The side faces include the side seal and the side wall of the packaging shell 40 connected to the side seal. After the electrochemical device 100 is packaged, the side seal can be folded to fit in the direction of the side wall of the packaging shell 40. By performing the folding process on the second end surface 44 and the two side surfaces 45 , the volume of the electrochemical device 100 can be reduced, thereby more effectively improving the energy density of the electrochemical device 100 .

[0034] In some embodiments of the present application, Figure 1 to Figure 2 , Figures 4 to 5As shown, the separator 20 includes a main body 21 and a bent portion 22 located at one edge of the main body 21. The bent portion 22 extends along one edge of the main body 21 to one side of the main body 21 and extends into the first recess 41 or the second recess 42. The bent portion 22 is in contact with and sealed to the first end face 43; the remaining edges of the main body 21 are sealed to the second end face 44 and the two side faces 45. In this way, the separator 20 is sealed to the packaging shell 40, so that the space inside the packaging shell 40 is divided into two cavities. As a result, the existence of the external folding edge of the first end face 43 is avoided, thereby increasing the energy density of the electrochemical device 100 and improving the packaging reliability of the electrochemical device 100.

[0035] Furthermore, if Figure 6 to Figure 7 As shown, the planar structure of the partition 20 is a "convex" shape. When sealed and connected to the packaging shell 40, the bent portion 22 is bent and forms a certain angle with the main body 21. It should be noted that, depending on the material of the partition 20 and the packaging shell 40, the angle between the bent portion 22 and the main body 21 will also change accordingly. For example, the angle between the bent portion 22 and the main body 21 is 70° to 110°. Preferably, the angle between the bent portion 22 and the main body 21 is about 90°. At this time, the bent portion 22 is more closely attached to the first end face 43, and the packaging reliability of the electrochemical device 100 is higher.

[0036] In some embodiments of the present application, the electrochemical device 100 further includes a packaging material, which covers at least the periphery of the two surfaces of the separator 20. It is understood that in some embodiments, the packaging material covers the periphery of the two surfaces (hereinafter referred to as the first surface and the second surface) of the separator 20; in other embodiments, the packaging material covers the edges of the first surface of the separator 20 and covers the entire area of ​​the second surface; in still other embodiments, the packaging material covers the entire area of ​​the first surface and the second surface of the separator 20. By covering the two surfaces of the separator 20 with the packaging material, the separator 20 is sealed and connected to the packaging shell 40 to separate the internal space of the packaging shell 40 into two independent cavities. Preferably, the packaging material only covers the periphery of the two surfaces of the separator 20, and the width or area of ​​the peripheral area can be adjusted according to the width of the sealing edge, so as to avoid the packaging material from increasing the thickness of the separator, and the thinner separator 20 is conducive to improving the energy density of the battery cell.

[0037] Furthermore, according to the change of the material of the partition 20 and the packaging shell 40, the sealing connection method of the partition 20 and the packaging shell 40, in addition to heat sealing, can also be selected from gluing, welding or sealing treatment of the metal and non-metal interface.

[0038] In some embodiments of the present application, the electrochemical device 100 further includes a packaging material, which covers the side of the bent portion 22 facing the first end surface 43. Thus, the bent portion 22 can be sealed and connected to the first end surface 43, so that the separator 20 is sealed and connected to the packaging shell 40, thus avoiding the existence of the outer fold of the first end surface 43.

[0039] In some embodiments of the present application, Figure 7 As shown, the edge of the main body 21 and the edge of the bent portion 22 form an angle area 23, and the packaging material also covers the angle area 23 to ensure that the two cavities separated by the partition 20 are independent of each other, thereby achieving the effect of isolating the electrolytes in each cavity from each other to prevent leakage of the electrolyte from causing the electrolyte to decompose and fail during high-voltage charging.

[0040] Furthermore, if Figure 7 As shown, the bending portion 22 includes a short side a and a long side b, the main body 21 includes a first side c connected to the bending portion 22, and the length of the long side b of the bending portion 22 is smaller than the length of the first side c, so that the main body 21 forms two extensions d relative to the bending portion 22 in the length direction of the bending portion 22, and the short side a of the bending portion 22 and the extension d respectively form two symmetrical angle areas 23 in the length direction (only one is shown in the figure). It should be noted that the size of the angle area 23 will change depending on the material of the partition 20 and the packaging shell 40. In the present application, there is no special restriction on the size of the angle area 23. Figure 7 The angle area 23 is for illustration only and does not limit the size. Those skilled in the art may select the amount of packaging material according to actual conditions, as long as the packaging material can cover the two angle areas 23 and achieve the purpose of this application.

[0041] In some embodiments of the present application, Figures 8 to 11As shown, the partition 20 also includes two side bends 24 located at the two side edges of the main body 21. Specifically, in some embodiments, the first end face 43 and the two side faces 45 of the packaging shell 40 are integrally formed, that is, the packaging shell 40 has no sealing edge and no external folding edge on the first end face 43 and the two side faces 45 (only one is shown in the figure). When the top seal on the side of the extended pole ear 50 is not encapsulated, the partition 20 is inserted into the packaging shell 40 through the top seal, and the packaging material covers the side of the bend 22 facing the first end face 43 and the side of the two side bends 24 facing the two side faces 45, so that the bend 22 is fitted and sealed with the first end face 43, and the two side bends 24 are fitted and sealed with the two side faces 45, and the top edge 211 of the main body 21 is sealed with the second end face 44. In this way, the partition 20 is sealed with the packaging shell 40, so that the space inside the packaging shell 40 is divided into two cavities. Thus, the existence of the external folding edges of the first end surface 43 and the two side surfaces 45 is avoided, so that the volume of the electrochemical device 100 is further reduced, thereby increasing the energy density of the electrochemical device 100 and effectively improving the packaging reliability of the electrochemical device 100 .

[0042] Furthermore, when the partition 20 is sealed and connected to the packaging shell 40, the two side bends 24 are bent and form a certain angle with the main body 21. It should be noted that, depending on the material of the partition 20 and the packaging shell 40, the angles between the two side bends 24 and the main body 21 may be the same or different. For example, the above angle is 70° to 110°. Preferably, the two side bends 24 form an angle of about 90° with the main body. At this time, the side bends 24 and the side 45 are more closely attached, and the packaging reliability of the electrochemical device 100 is higher.

[0043] Furthermore, in order to ensure that the two cavities separated by the partition 20 are independent of each other, the connection between the bending portion 22 and the two side bending portions 24 is covered with packaging material, or the bending portion 22 and the two side bending portions 24 are integrally formed by pre-pressing or the like, and the angle area formed by the top edge 211 and the edges of the two side bending portions 24 is also covered with packaging material, thereby achieving the isolation effect of each cavity.

[0044] In some embodiments of the present application, the packaging material includes at least one of polypropylene, anhydride-modified polypropylene, polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid copolymer, ethylene-vinyl alcohol copolymer, polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, epoxy resin, polyamide, polyester, amorphous α-olefin copolymer and its derivatives. The use of the above packaging materials can more effectively improve the sealing, thereby improving the packaging reliability of the electrochemical device 100. It should be noted that the present application has no particular restrictions on the packaging temperature, packaging time and packaging pressure, as long as the purpose of the present application can be achieved. For example, the packaging material is polypropylene, the packaging temperature is 180°C to 195°C, the packaging time is 2s to 4s, and the packaging pressure is 0.2MPa to 0.5MPa.

[0045] In some embodiments of the present application, Figures 2 to 3 As shown, each electrode assembly 10 is provided with a pole tab 50 of different polarity, the pole tab 50 extends out of the packaging shell 40, and adjacent electrode assemblies 10 are connected in series through the pole tab 50. Specifically, in one embodiment, the first electrode assembly 11 is provided with a first positive pole tab 51 and a first negative pole tab 52, and the second electrode assembly 12 is provided with a second positive pole tab 53 and a second negative pole tab 54, the first positive pole tab 51, the first negative pole tab 52, the second positive pole tab 53 and the second negative pole tab 54 all extend out of the packaging shell 40 without overlapping, and the adjacent first electrode assembly 11 and the second electrode assembly 12 are connected in series through the first negative pole tab 52 and the second positive pole tab 53, and the first positive pole tab 51 and the second negative pole tab 54 serve as positive and negative terminals for connection during charging and discharging. When all the tabs 50 provided on each electrode assembly 10 are extended out of the packaging shell 40 for welding, the welding effect of the tabs 50 can be monitored at any time to reduce the risk of breakage of the tabs 50 and avoid the problem of increased internal resistance of the electrochemical device 100 due to poor welding effect of the tabs 50; adjacent electrode assemblies 10 are connected in series, which can effectively improve the output voltage of the electrochemical device 100.

[0046] Furthermore, the first negative electrode tab 52 and the second positive electrode tab 53 that are connected in series to the adjacent first electrode assembly 11 and the second electrode assembly 12 may also extend out of the packaging shell 40 in a manner that at least partially overlaps.

[0047] In some embodiments of the present application, the thickness of the separator is 6 μm to 100 μm, preferably 10 μm to 40 μm, and more preferably 20 μm to 30 μm. When the thickness of the separator is too thin (e.g., less than 6 μm), the mechanical strength of the separator may be insufficient, and it is easy to cause damage, thereby affecting the performance and even safety of the electrochemical device; when the thickness of the separator is too thick (e.g., greater than 100 μm), the volume of the electrochemical device increases, thereby reducing the energy density of the electrochemical device.

[0048] In some embodiments of the present application, the material of the partition includes at least one of a polymer film, a metal foil or a carbon material. The present application has no particular restrictions on the type of polymer film, as long as the purpose of the present application can be achieved. For example, the polymer film may include polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate, polyetheretherketone, polyimide (PI), polyamide (PA), polyethylene glycol, polyamideimide, polycarbonate, cyclic polyolefin (PO), polyphenylene sulfide, polyvinyl acetate, polytetrafluoroethylene, polymethylene naphthalene, polyvinylidene fluoride, polyethylene naphthalate, polypropylene carbonate, poly (vinylidene fluoride-hexafluoropropylene), poly (vinylidene fluoride-co-chlorotrifluoroethylene), silicone resin, vinylon, polypropylene (PP), polyethylene (PE), polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, polyphenylene oxide, polysulfone, amorphous α-olefin copolymer and at least one of its derivative films. The present application does not particularly limit the type of metal foil, as long as the purpose of the present application can be achieved. For example, the metal foil may include 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 its combination or alloy. The present application does not particularly limit the type of carbon material, as long as the purpose of the present application can be achieved. For example, the carbon material may include at least one of single-walled carbon nanotubes (SWCNT), multi-walled carbon nanotubes (MWCNT), carbon felt, carbon film, carbon black, acetylene black, fullerene, conductive graphite film or graphene film.

[0049] Preferably, the material of the partition includes a polymer film, which has a low density and can reduce the weight of the partition, thereby increasing the energy density of the lithium-ion battery. In addition, under mechanical abuse conditions (e.g., nail penetration, impact, extrusion, etc.), the polymer film has a lower probability of generating debris and has a better wrapping effect on the mechanically damaged surface, which can improve the safety performance under the above-mentioned mechanical abuse conditions, thereby improving the safety test pass rate and further improving the safety performance of the lithium-ion battery. Preferably, the material of the partition includes a metal foil, which has strong isolation reliability, good toughness and density, and can be processed thinner, which can increase the energy density of the lithium-ion battery. Preferably, the material of the partition includes a carbon material, which has excellent safety performance, good thermal conductivity and excellent high-temperature reliability. Preferably, the material of the partition includes a composite material composed of at least two of a polymer film, a metal foil or a carbon material. The type of the composite material is not particularly limited, as long as the purpose of the present application can be achieved. For example, the composite material may include a Ni metal foil composite PP film, an Ag metal foil composite PET film, a polyurethane / stainless steel / polyurethane composite material or a PP / Al / PP composite material, etc.

[0050] In some embodiments of the present application, the separator is a bipolar separator, and the bipolar separator may include at least one of a Cu-Al composite current collector, a stainless steel foil current collector, or a polymer conductive current collector.

[0051] The present application does not particularly limit the type of polymer conductive current collector, as long as the purpose of the present application can be achieved. For example, the polymer conductive current collector may include a composite material of a polymer material and a conductive material. Specifically, a polymer conductive current collector includes a polymer matrix and a one-dimensional or two-dimensional conductive material, and the conductive material is distributed in the polymer matrix in a direction of 0° to 30° with the thickness direction of the polymer matrix. Another polymer conductive current collector includes a porous polymer matrix, and the conductive material is located in the pores of the porous polymer matrix, so that the two surfaces of the polymer conductive current collector are electronically conductive. Another polymer conductive current collector is a polymer material having the same or different metal material layers on each of the two surfaces.

[0052] The present application does not particularly limit the type of polymer conductive current collector, as long as the purpose of the present application can be achieved. For example, it can be obtained by the following method: spraying a polymer material on a stainless steel substrate to obtain a polymer material layer, heating the polymer material layer to soften it, then implanting a one-dimensional or two-dimensional conductive material, then spraying the polymer material again to form a polymer film, overheating and rolling the obtained polymer film, removing the polymer film from the surface of the stainless steel substrate with a scraper, and rolling up to obtain a polymer conductive current collector. The polymer conductive current collector can also be obtained by dispersing a zero-dimensional conductive material in a polymer material.

[0053] The present application has no particular limitation on the type of conductive material, as long as the purpose of the present application can be achieved.

[0054] In some embodiments of the present application, an electrode active material layer is provided on the first side of the bipolar separator, an electrode active material layer with opposite polarity is provided on the outermost layer of the electrode assembly adjacent to the electrode active material layer, a diaphragm is provided between the first side of the bipolar separator and the adjacent electrode assembly, the second side of the bipolar separator is electrically insulated from the adjacent electrode assembly, and the bipolar separator leads out a pole ear, which is connected to the pole ears of the electrode assemblies connected in series on both sides. In these embodiments, the first side of the bipolar separator and the outermost electrode sheet of the adjacent electrode assembly constitute an electrochemical unit, participate in the charging and discharging process of the lithium-ion battery, and improve the energy density of the lithium-ion battery. A pole ear is led out on the bipolar separator, and the pole ear is connected to the pole ears of the electrode assemblies connected in series on both sides, thereby providing a high output voltage.

[0055] In other embodiments of the present application, an electrode active material layer is disposed on the first side of the bipolar separator, an electrode active material layer with opposite polarity is disposed on the outermost layer of the electrode assembly adjacent to the electrode active material layer, a separator is disposed between the first side of the bipolar separator and the adjacent electrode assembly, and the second side of the bipolar separator is electrically connected to the adjacent electrode assembly. The above-mentioned "electrical connection" means that the second side of the bipolar separator is connected to the circuit by physically contacting the outermost current collector of the adjacent electrode assembly, that is, there is no electrode active material on the surface of the electrode plate electrically connected to the bipolar separator.

[0056] Furthermore, the bipolar separator may not lead out the pole ears. In this case, the electrode assemblies on both sides of the bipolar separator are directly connected in series internally through the bipolar separator. The lithium-ion battery may only lead out two pole ears with opposite polarities. When the lithium-ion battery contains more than two electrode assemblies, all electrode assemblies are connected in series between the above two pole ears with opposite polarities through the bipolar separator.

[0057] Furthermore, the bipolar separator may also lead out a pole ear, which is connected to the pole ear of the same polarity on the electrode assembly on the first side of the bipolar separator to form a parallel connection, and then connected to the pole ear of the opposite polarity on the electrode assembly on the second side to form a series connection. At this time, the two electrode assemblies can be connected in series through the inside of the bipolar separator and through the outside of the pole ear. In addition, the pole ear of the bipolar separator may not be connected to the pole ear of the electrode assembly, and is only used to monitor the voltage of the electrochemical device, so that the problematic electrode assembly can be checked in time, the cause of failure can be found, and the manufacturing rate and production efficiency of the electrochemical device can be improved.

[0058] In some other embodiments of the present application, electrode active material layers of different polarities are provided on both sides of the bipolar separator, and the outermost layer of the electrode assembly adjacent to each electrode active material layer is provided with an electrode active material layer of opposite polarity, and a separator is provided between the electrode active material layer of the bipolar separator and the outermost electrode active material layer of the electrode assembly. Electrode active material layers of different polarities are provided on both sides of the bipolar separator, and both sides form an electrochemical unit with the outermost electrode sheets of the adjacent electrode assemblies, further improving the energy density of the lithium-ion battery.

[0059] The electrode assemblies on both sides of the bipolar separator can be directly connected in series internally through the bipolar separator, or can be simultaneously connected in series internally and externally through the bipolar separator and two pole ears with opposite polarities.

[0060] Furthermore, electrode active material layers with different polarities are provided on both sides of the bipolar separator, and a tab is provided on the bipolar separator, which can be used to monitor the voltage of the electrochemical device or to insulate the tab. The tab can also be connected to the series tabs of the electrode assemblies on both sides of the bipolar separator.

[0061] In the present application, there is no particular limitation on the structure of the electrode assembly, as long as the purpose of the present application can be achieved. For example, the structure of the electrode assembly may include at least one of a winding structure or a laminated structure.

[0062] The present application has no particular restrictions on the material of the pole ear, as long as the purpose of the present application can be achieved. For example, the positive pole ear material includes at least one of aluminum (Al) or aluminum alloy, and the negative pole ear material includes at least one of nickel (Ni), copper (Cu) or copper-plated nickel (Ni-Cu). The present application has no particular restrictions on the welding method of the pole ear, as long as the purpose of the present application can be achieved. For example, at least one of laser welding, ultrasonic welding or resistance welding. The present application has no particular restrictions on the direction in which different pole ears are led out, as long as the purpose of the present application can be achieved. For example, the direction in which the pole ears are led out can be in the same direction or in different directions.

[0063] In the present application, the electrode assembly may include a diaphragm, a positive electrode sheet, and a negative electrode sheet. The diaphragm is used to separate the positive electrode sheet and the negative electrode sheet to prevent short circuits inside the electrochemical device. It allows electrolyte ions to pass freely to complete the electrochemical charge and discharge process. The present application does not specifically limit the number of diaphragms, positive electrode sheets, and negative electrode sheets, as long as the purpose of the present application can be achieved.

[0064] The present application has no particular restrictions on the type of diaphragm, as long as the purpose of the present application can be achieved. For example, polyethylene (PE), polypropylene (PP)-based polyolefin (PO)-based diaphragms, polyester films (such as polyethylene terephthalate (PET) films), cellulose films, polyimide films (PI), polyamide films (PA), spandex or aramid films, woven films, nonwoven films (non-woven fabrics), microporous films, composite films, diaphragm paper, rolled films, spinning films, etc. At least one. For example, the diaphragm may include a substrate layer and a surface treatment layer. The substrate layer may be a non-woven fabric, a film or a composite film with a porous structure, and the material of the substrate layer may include at least one of polyethylene, polypropylene, polyethylene terephthalate and polyimide, etc. Optionally, polypropylene porous film, polyethylene porous film, polypropylene non-woven fabric, polyethylene non-woven fabric or polypropylene-polyethylene-polypropylene porous composite film may be used. Optionally, a surface treatment layer is provided on at least one surface of the substrate layer, and the surface treatment layer can be a polymer layer or an inorganic layer, or a layer formed by a mixed polymer and an inorganic substance. For example, the inorganic layer includes inorganic particles and a binder, and the inorganic particles are not particularly limited, and for example, can be selected from at least one of aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, 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 for example, can be selected from at least one of polyvinylidene fluoride, a copolymer of vinylidene fluoride-hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene and polyhexafluoropropylene. The polymer layer contains polymers, and the polymer material includes at least one of polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride or poly(vinylidene fluoride-hexafluoropropylene).

[0065] The present application places no particular restrictions on the positive electrode sheet, as long as the objectives of the present application can be achieved. For example, the positive electrode sheet generally includes a positive electrode current collector and a positive electrode active material layer. Among them, there are no particular restrictions on the positive electrode current collector, as long as the objectives of the present application can be achieved. For example, it may include aluminum foil, aluminum alloy foil, or composite current collector, etc. The positive electrode active material layer includes positive electrode active materials. There are no particular restrictions on the types of positive electrode active materials, as long as the objectives of the present application can be achieved. For example, it may include at least one of lithium nickel cobalt manganate (811, 622, 523, 111), lithium nickel cobalt aluminate, lithium iron phosphate, lithium-rich manganese-based material, lithium cobalt oxide, lithium manganese oxide, lithium manganese iron phosphate, or lithium titanate, etc. In the present application, there are no particular restrictions on the thicknesses of the positive electrode current collector and the positive electrode active material layer, as long as the objectives of the present application can be achieved. For example, the thickness of the positive electrode current collector is 5 μm to 20 μm, preferably 6 μm to 18 μm, and more preferably 8 μm to 16 μm. The thickness of the positive electrode material layer is 30 μm to 120 μm. In the present application, there are no particular restrictions on the thickness of the positive electrode sheet, as long as the objectives of the present application can be achieved. For example, the thickness of the positive electrode sheet is 35 μm to 140 μm. Optionally, the positive electrode sheet may further include a conductive layer, which is located between the positive electrode current collector and the positive electrode material layer. The composition of the conductive layer is not particularly limited and may be a commonly used conductive layer in the art. The conductive layer includes a conductive agent and a binder.

[0066] The present application places no particular restrictions on the negative electrode sheet, as long as the objectives of the present application can be achieved. For example, the negative electrode sheet generally includes a negative electrode current collector and a negative electrode active material layer. Among them, there are no particular restrictions on the negative electrode current collector, as long as the objectives of the present application can be achieved. For example, it may include copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, or composite current collector, etc. The negative electrode active material layer includes a negative electrode active material, a conductive agent, and a thickening agent. There are no particular restrictions on the types of negative electrode active materials, as long as the objectives of the present application can be achieved. For example, it may include natural graphite, artificial graphite, mesocarbon microbeads (MCMB), hard carbon, soft carbon, silicon, silicon-carbon composite, SiO x (0 < x < 2), Li-Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO2, spinel-structured lithium titanate Li4Ti5O 12, Li-Al alloy and metallic lithium, etc. In the present application, there is no particular restriction on the thickness of the negative electrode current collector and the negative electrode active material layer, as long as the purpose of the present application can be achieved. For example, the thickness of the negative electrode current collector is 6μm to 10μm, and the thickness of the negative electrode active material layer is 30μm to 120μm. In the present application, there is no particular restriction on the thickness of the negative electrode pole piece, as long as the purpose of the present application can be achieved. For example, the thickness of the negative electrode pole piece is 50μm to 150μm. Optionally, the negative electrode pole piece may also include a conductive layer, which is located between the negative electrode current collector and the negative electrode material layer. The composition of the conductive layer is not particularly limited, and it may be a conductive layer commonly used in the art. The conductive layer includes a conductive agent and a binder.

[0067] The present application has no particular restrictions on the conductive agent, as long as the purpose of the present application can be achieved. For example, the conductive agent may include at least one of conductive carbon black (Super P), carbon nanotubes (CNTs), carbon nanofibers, flake graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes or graphene, etc. The present application has no particular restrictions on the binder, as long as the purpose of the present application can be achieved. For example, the binder may include at least one of polypropylene alcohol, sodium polyacrylate, potassium polyacrylate, lithium polyacrylate, polyimide, polyimide, polyamide-imide, styrene-butadiene rubber (SBR), polyvinyl alcohol (PVA), polyvinylidene fluoride, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl butyral (PVB), water-based acrylic resin, carboxymethyl cellulose (CMC) or sodium carboxymethyl cellulose (CMC-Na), etc.

[0068] In the present application, the electrode active material layer refers to the above-mentioned positive electrode active material layer or negative electrode active material layer.

[0069] The present application has no particular restrictions on the electrolyte, as long as the purpose of the present application can be achieved. For example, the electrolyte generally includes a lithium salt and a non-aqueous solvent. In some embodiments of the present application, the lithium salt may include at least one of LiPF6, LiBF4, LiAsF6, LiClO4, LiB(C6H5)4, LiCH3SO3, LiCF3SO3, LiN(SO2CF3)2, LiC(SO2CF3)3, LiSiF6, LiBOB or lithium difluoroborate. For example, the lithium salt may be selected from LiPF6 because it can provide high ionic conductivity and improve cycle characteristics. The non-aqueous solvent may be at least one of a carbonate compound, a carboxylate compound, an ether compound or other organic solvents. The carbonate compound may be at least one of a chain carbonate compound, a cyclic carbonate compound or a fluorinated carbonate compound. The chain carbonate compound may include at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), or methylethyl carbonate (MEC), etc. The cyclic carbonate compound may include at least one of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), or vinylethylene carbonate (VEC), etc. The fluorinated carbonate compound may include at least one of fluoroethylene carbonate (FEC), 1,2-difluoroethylene 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, or trifluoromethylethylene carbonate, etc. The carboxylate compound may include at least one of methyl formate, methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, γ-butyrolactone, decanoic acid lactone, valerolactone, mevalonolactone or caprolactone, etc. The ether compound may include at least one of dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxyethane, 2-methyltetrahydrofuran or tetrahydrofuran, etc. The above-mentioned other organic solvents may include at least one of dimethyl sulfoxide, 1,2-dioxolane, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, formamide, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, trioctyl phosphate or phosphate, etc.

[0070] The present application has no particular restrictions on the packaging shell, as long as the purpose of the present application can be achieved. For example, the packaging shell may include an inner layer and an outer layer, and the inner layer is sealed and connected to the partition, so the material of the inner layer may include a polymer material, thereby achieving a good sealing effect; at the same time, the combination of the inner layer and the outer layer can effectively protect the internal structure of the electrochemical device. Specifically, the material of the inner layer includes at least one of polypropylene, polyester, p-hydroxybenzaldehyde, polyamide, polyphenylene ether, polyurethane, etc. In the present application, there is no particular restriction on the material of the outer layer, as long as the purpose of the present application can be achieved. For example, the material of the outer layer may include at least one of aluminum foil, aluminum oxide layer, silicon nitride layer, etc. In addition, the packaging shell may also be an aluminum-plastic film, which includes a nylon layer, an aluminum foil layer, and a PP layer. The packaging shell may also be a steel shell after insulation treatment.

[0071] In the present application, there is no particular limitation on the thickness of the packaging shell, as long as the purpose of the present application can be achieved. For example, the thickness of the packaging shell can be 50 μm to 500 μm, preferably 50 μm to 300 μm, and more preferably 50 μm to 200 μm. The packaging shell within the above thickness range can effectively protect the internal structure of the electrochemical device.

[0072] In the present application, there is no special restriction on the size of the seal edge, as long as the purpose of the present application can be achieved. For example, the thickness T (unit: mm) and width W (unit: mm) of the seal edge satisfy 0.01≤T / W≤0.05. The ratio of T / W within the above range can ensure that the battery is well sealed and the service life of the battery is improved. When T / W is too small, the seal thickness may be insufficient, the sealing effect is not good, and the environmental stability of the battery is reduced. For example, water vapor in the environment can easily penetrate into the battery, resulting in an increase in the moisture content in the battery, electrolyte decomposition, and a reduction in the service life of the battery; if the ratio of T / W is too large, the seal width W may be too small, and there is also a poor sealing effect, resulting in a reduction in the environmental stability of the battery. For example, water vapor in the environment can easily penetrate into the battery, resulting in an increase in the moisture content in the battery, electrolyte decomposition, and other problems, reducing the service life of the battery. In the present application, the seal thickness and seal width are not particularly limited, as long as the purpose of the present application can be achieved. For example, the width W of the seal edge is preferably 1mm to 7mm. It should be noted that during the packaging process, the polymer material in the packaging shell and the packaging material are sealed together by heat pressing. Therefore, the seal thickness includes the thickness after the packaging material and the inner polymer material of the packaging shell are fused. The seal width refers to the width of the sealed area formed by the packaging material and the inner polymer material of the packaging shell after heat pressing.

[0073] The electrochemical device of the present application may also include other devices that generate electrochemical reactions, such as lithium metal secondary batteries, lithium polymer secondary batteries, or lithium ion polymer secondary batteries.

[0074] The present application does not particularly limit the preparation process of the electrochemical device, as long as the purpose of the present application can be achieved. For example, the electrochemical device can be prepared by the following process: the positive electrode sheet and the negative electrode sheet are overlapped via a diaphragm, and after winding or folding them as needed, they are placed in a housing, and the electrolyte is injected into the housing and sealed. In addition, overcurrent protection elements, guide plates, etc. can also be placed in the housing as needed to prevent pressure rise and overcharge and discharge inside the electrochemical device.

[0075] The electrochemical device provided by the present application is formed by one side wall of the first recess and one side wall of the second recess to form a first end face, and one edge of the partition is sealed and connected to the first end face, which reduces the loss of energy density caused by the external folding of the first end face, thereby effectively improving the energy density of the electrochemical device. In addition, without the external folding of the first end face, the risk of packaging failure of the electrochemical device is reduced, further improving the safety performance of the electrochemical device. At the same time, it can also significantly reduce the production cost of the electrochemical device.

[0076] For example, in one embodiment of the present application, the packaging shell is an aluminum-plastic film comprising a nylon layer, an aluminum foil layer and a PP layer, with a thickness of 88 μm; the first electrode assembly and the second electrode assembly are both wound structures; the separator is a PP / Al / PP composite separator, and the thickness of each layer is 30 μm, that is, the thickness of the separator is 90 μm, the separator includes a main body and a bending portion, the angle between the bending portion and the main body is 90°, the bending portion is in contact with the first end face of the packaging shell and is sealed by heat sealing the PP layer on the surface of the partition and the PP layer of the aluminum-plastic film, the angle area is sealed by dripping the packaging material epoxy resin, the sealing edge of the main body and the second end face and the sealing edges of the two side surfaces are sealed by the PP layer on the surface of the partition and the PP layer inside the packaging shell, the packaging temperature is 190°C, the packaging time is 3s, and the packaging pressure is 0.4 MPa, thereby achieving physical isolation between the first electrode assembly 11 and the second electrode assembly 12.

[0077] In another embodiment of the present application, the packaging shell is a steel shell with a thickness of 80 μm, and the inner surface of the steel shell is coated with polyurethane for insulation; the first electrode assembly and the second electrode assembly are both laminated structures; the partition is a composite partition of polyurethane / stainless steel / polyurethane, and the thickness of the three-layer material is 1 μm / 10 μm / 1 μm, that is, the thickness of the partition is 12 μm, and the partition includes a main body and a bending portion, and the angle between the bending portion and the main body is 90°. The bending portion is in contact with the first end face of the packaging shell and is sealed by heat sealing the polyurethane layer on the surface of the partition and the polyurethane layer on the inner surface of the steel shell. The angle area is sealed by applying the packaging material polyurethane, and the main body and the packaging shell are sealed by the packaging material. The packaging temperature is 190°C, the packaging time is 3s, and the packaging pressure is 0.4MPa, thereby realizing physical isolation between the first electrode assembly 11 and the second electrode assembly 12.

[0078] The second aspect of the present application provides an electronic device, comprising the electrochemical device provided in the first aspect of the present application. The electronic device has good energy density and safety performance.

[0079] The electronic devices of the present application are not particularly limited and may include but are not limited to: laptop computers, pen-input computers, mobile computers, e-book players, portable phones, portable fax machines, portable copiers, portable printers, head-mounted stereo headphones, video recorders, LCD televisions, portable cleaners, portable CD players, mini CDs, transceivers, electronic notepads, calculators, memory cards, portable recorders, radios, backup power supplies, motors, cars, motorcycles, power-assisted bicycles, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries and lithium-ion capacitors, etc.

[0080] It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity from another entity, and do not necessarily require or imply any such actual relationship or order between these entities. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that an article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such article or device.

[0081] Each embodiment in this specification is described in a related manner, and the same or similar parts between the embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0082] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. An electrochemical device, comprising a packaging shell, a separator, and electrode assemblies respectively arranged on both sides of the separator, each electrode assembly being provided with a tab, characterized in that: The packaging shell is respectively provided with a first recess and a second recess on both sides of the partition, and a side wall of the first recess is integrally formed with a side wall of the second recess to form a first end face of the packaging shell; the packaging shell also includes a second end face arranged opposite to the first end face and two side faces connected between the first end face and the second end face and arranged opposite to each other, and the electrode ear extends out of the second end face; the partition includes a main body and a bent portion located at an edge of the main body, the bent portion extends into the first recess or the second recess and is in contact with and sealed with the first end face; the remaining edges of the main body are respectively sealed with the second end face and the two side faces, thereby dividing the space inside the packaging shell into two cavities, each cavity encapsulating the electrode assembly and the electrolyte.

2. The electrochemical device according to claim 1, characterized in that The electrochemical device further includes a packaging material, which covers at least peripheries of two surfaces of the separator.

3. The electrochemical device according to claim 1, characterized in that The electrochemical device further includes a packaging material, wherein the packaging material covers a side of the bent portion facing the first end surface.

4. The electrochemical device according to claim 3, characterized in that The edge of the main body and the edge of the bent portion form an angle region, and the packaging material also covers the angle region.

5. The electrochemical device according to any one of claims 2 to 4, characterized in that The packaging material includes at least one of polypropylene, anhydride-modified polypropylene, polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid copolymer, ethylene-vinyl alcohol copolymer, polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, epoxy resin, polyamide, polyester, amorphous α-olefin copolymer and its derivatives.

6. The electrochemical device according to claim 1, characterized in that Each of the electrode assemblies is provided with a pole lug of different polarity, the pole lug extends out of the packaging shell, and adjacent electrode assemblies are connected in series through the pole lugs.

7. The electrochemical device according to claim 1, characterized in that The separator has a thickness of 6 μm to 100 μm.

8. The electrochemical device according to claim 1, characterized in that The material of the separator includes at least one of a polymer film, a metal foil or a carbon material.

9. An electronic device, characterized in that: An electrochemical device comprising any one of claims 1 to 8.

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