WO2023283830A1

WO2023283830A1 - Electrochemical apparatus and electronic apparatus comprising same

Info

Publication number: WO2023283830A1
Application number: PCT/CN2021/106275
Authority: WO
Inventors: 丁宇; 刘道林
Original assignee: 宁德新能源科技有限公司
Priority date: 2021-07-14
Filing date: 2021-07-14
Publication date: 2023-01-19
Also published as: CN115004441A

Abstract

The present application provides an electrochemical apparatus and an electronic apparatus comprising same. The electrochemical apparatus comprises a packaging housing, a partition plate, and electrode assemblies, which are respectively arranged on two sides of the partition plate. Each electrode assembly is provided with a tab. The packaging housing is provided with a first recess and a second recess on the two sides of the partition plate, respectively; and one side wall of the first recess and one side wall of the second recess are integrally formed to form a first end face of the packaging housing. The packaging housing further comprises a second end face, which is opposite the first end face; and two side faces, which are opposite each other and are connected between the first end face and the second end face. The tabs extend out of the second end face; and the partition plate is connected, in a sealed manner, to the first end face, the second end face and the two side faces, such that a space inside the packaging housing is divided into two cavities, and the electrode assembly and an electrolyte are packaged in each cavity. The electrochemical apparatus and the electronic apparatus have good energy density.

Description

An electrochemical device and an electronic device comprising the electrochemical device

technical field

The present application relates to the field of electrochemistry, in particular to an electrochemical device and an electronic device including the electrochemical device.

Background technique

With the development of science and technology, there are more and more applications for lithium-ion batteries in the fields of power tools and drones. These two fields require batteries to have the function of instantaneous high-power discharge, while the traditional battery discharge voltage platform is only 3.8V To about 4.3V, it cannot meet its needs.

In order to increase the output voltage of lithium-ion batteries, in the prior art, different numbers of lithium-ion batteries are usually connected in series through an external printed circuit board (PCB) to achieve a boost function. However, this series connection method will occupy a volume space and cause a loss of energy density (ED).

Contents of the invention

The present application provides an electrochemical device and an electronic device including the electrochemical device, so as to improve its energy density.

The first aspect of the present application provides an electrochemical device, including a packaging case, a separator, and electrode assemblies respectively arranged on both sides of the separator. Each electrode assembly is provided with tabs. 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 surface of the packing shell. The packing case also includes a second end face opposite to the first end face and two side faces connected between the first end face and the second end face. The tab extends out of the second end surface. The partition is sealed and connected with the first end surface, the second end surface and the two side surfaces, thereby separating the space inside the packaging shell into two cavities. Each cavity encapsulates an electrode assembly and an electrolyte.

In the electrochemical device of the present application, the side wall of the first recess and the side wall of the second recess on the packaging case are integrally formed as the first end surface of the packaging case, and one edge of the separator is connected to the first end surface. Sealed connection, compared with the prior art, the edge of the separator does not need to be clamped between the upper and lower side walls of the first end surface of the packaging shell, which reduces the risk of package failure of the electrochemical device and improves the safety of the electrochemical device performance; at the same time, avoiding the existence of the outer edge of the first end face, reducing the loss of energy density caused by the outer edge of the first end face, thus not only effectively improving the energy density of the electrochemical device, but also significantly reducing the electrochemical energy density. The production cost of the device.

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 seals the first end surface. The remaining edges of the main body are respectively sealed and connected to the second end surface and the two side surfaces. Thus, the existence of the outer edge of the first end surface is avoided, thereby increasing the energy density of the electrochemical device and improving the packaging reliability of the electrochemical device.

In some embodiments of the present application, the electrochemical device further includes an encapsulation material covering at least peripheries of two surfaces of the separator. Through the arrangement of the packaging material on the surface of the partition, the reliability of the sealed connection between the partition and the packaging case is improved, thereby separating the inner space of the packaging case into two independent cavities.

In some embodiments of the present application, the electrochemical device further includes an encapsulation material, and the encapsulation material covers a side of the bent portion facing the first end surface. Thus, the bending portion can be sealed and connected with the first end surface, so that the partition plate is sealed and connected with the packaging shell, thus avoiding the existence of the outer edge of the first end surface.

In some embodiments of the present application, the edge of the main body part and the edge of the bent part form an angled area, and the encapsulation material also covers the angled area, so as to ensure that the two cavities formed by the partition are also hermetically connected in the angled area , thereby achieving the effect of isolating the electrolytes in each cavity from each other, so as to prevent the electrolyte from leaking and causing the electrolyte to decompose and fail during high-voltage charging.

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

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

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

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

The second aspect of the present application provides an electronic device, including 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.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application and the prior art, the following briefly introduces the accompanying drawings required in the embodiments and the prior art. Obviously, the accompanying drawings in the following description are only the present invention. Some examples of applications.

Fig. 1 is a schematic diagram of the internal structure of the packaging shell of the embodiment of the present application;

Fig. 2 is the schematic structural diagram of the electrochemical device of the embodiment of the present application;

Fig. 3 is a schematic diagram of an exploded structure of an electrochemical device according to some embodiments of the present application;

Fig. 4 is a schematic diagram of an exploded structure of an electrochemical device according to another embodiment of the present application;

Fig. 5 is a schematic diagram of an exploded structure of an electrochemical device according to some further embodiments of the present application;

Fig. 6 is a schematic plan view of a partition in some embodiments of the present application;

Fig. 7 is a schematic diagram of the three-dimensional structure of the separator in some embodiments of the present application;

Fig. 8 is a schematic diagram of a three-dimensional structure of a partition in another embodiment of the present application;

Fig. 9 is a schematic structural diagram of an electrochemical device according to another embodiment of the present application (a shows the direction of A-A, and b shows the direction of B-B);

Fig. 10 is a schematic cross-sectional structure diagram of the electrochemical device of Fig. 9 along the A-A direction;

FIG. 11 is a schematic cross-sectional structure diagram of the electrochemical device in FIG. 9 along the B-B direction.

Reference signs: 100. Electrochemical device; 10. Electrode assembly; 11. First electrode assembly; 12. Second electrode assembly; 20. Separator; 21. Main body; ; 24. side bending part; 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. The first positive pole ear; 52. The first negative pole ear; 53. The second positive pole ear; 54. The second negative pole ear.

detailed description

In order to make the purpose, technical solution and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. Apparently, the described embodiments are only some of the embodiments of this application, not all of them. All other technical solutions obtained by persons of ordinary skill in the art based on the embodiments in this application belong to the protection scope of this application.

It should be noted that, in the specific embodiments of the present application, a lithium-ion battery is used as an example of an electrochemical device to explain the present application, but the electrochemical device of the present application is not limited to the lithium-ion battery. The specific technical scheme is as follows:

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

In the electrochemical device 100 of the present application, the packaging case 40 is respectively provided with a first recess 41 and a second recess 42 on both sides of the separator 20, and the side wall of the first recess 41 and the side wall of the second recess 42 are integrally formed. In order to form the first end surface 43 , that is, the side of the first end surface 43 of the packaging shell 40 is integrally formed, and has no sealing edge and no external folding edge. Moreover, one edge of the separator 20 is sealed and connected to the first end surface 43, and the above-mentioned edge of the separator 20 can be sealed and connected to the packaging shell 40 without the existence of the sealing edge, and the risk of packaging failure of the electrochemical device 100 is reduced, making the electrochemical device The safety performance of the electrochemical device 100 is improved, and the loss of energy density caused by the external folding of the first end surface 43 is reduced, so that the energy density of the electrochemical device 100 can be effectively improved. At the same time, the design of the separator 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 separator 20 divides the space inside the packaging case 40 into two cavities, each cavity is packaged with the electrode assembly 10 and the electrolyte, and ion insulation is realized between the cavities, so as to avoid the 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 electrical energy output of the electrochemical device 100 .

In the present application, “first end surface”, “second end surface” and “side surface” all refer to the surface in the length or width direction of the electrochemical device 100 , not the surface in the thickness direction of the electrochemical device 100 . Wherein, "the second end surface" refers to the end surface of the electrochemical device 100 protruding from the side of the tab 50, including the top sealing edge and the side wall of the packaging case 40 connected to the top sealing edge. After the device 100 is packaged, it can be folded to be attached to the side wall of the packaging case 40 . "Both sides" 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 sides are oppositely arranged in the length or width direction of the electrochemical device 100, and the side faces include side seals and side seals. The side wall of the packaging case 40 connected by edge sealing, after the electrochemical device 100 is packaged, the side sealing can be folded so as to be attached to the side wall of the packaging case 40 . Folding the second end surface 44 and the two side surfaces 45 can reduce the volume of the electrochemical device 100 , so that the energy density of the electrochemical device 100 can be improved more effectively.

In some embodiments of the present application, as shown in FIG. 1 to FIG. 2 and FIG. 4 to FIG. 5 , the separator 20 includes a main body portion 21 and a bent portion 22 located at one edge of the main body portion 21, and the bent portion 22 is along the One edge of the main body 21 extends toward one side of the main body 21 and extends into the first recess 41 or the second recess 42, and the bent portion 22 fits and seals against the first end surface 43; the remaining edges of the main body 21 are in contact with Both the second end surface 44 and the two side surfaces 45 are sealed and connected. In this way, the partition 20 is sealed and connected with the packaging case 40 , so that the space inside the packaging case 40 is divided into two cavities. Thus, the existence of the outer edge of the first end surface 43 is avoided, thereby increasing the energy density of the electrochemical device 100 and improving the packaging reliability of the electrochemical device 100 .

Further, as shown in FIGS. 6 to 7 , the planar structure of the separator 20 is a “convex” shape, and when it is sealed and connected with the packaging case 40 , the bending portion 22 is bent to form a certain angle with the main body 21 . It should be noted that, according to the different materials of the partition plate 20 and the package case 40 , the included angle between the bent portion 22 and the main body portion 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 The tighter the bonding with the first end surface 43 , the higher the packaging reliability of the electrochemical device 100 .

In some embodiments of the present application, the electrochemical device 100 further includes an encapsulation material, and the encapsulation material covers at least the peripheries of the two surfaces of the separator 20 . It can be understood that, in some embodiments, the encapsulation 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 encapsulation material covers the first surface of the separator 20. In some embodiments, the encapsulation material covers the entire area of the first surface and the second surface of the separator 20 . By covering the two surfaces of the partition 20 with the packaging material, the partition 20 is sealed and connected to the packaging case 40, so as to divide the inner space of the packaging case 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 region can be adjusted according to the width of the sealing edge, thereby avoiding the increase of the thickness of the separator caused by the packaging material, and the thinner separator 20 It is beneficial to improve the energy density of the battery cell.

Further, according to the change of the material of the partition 20 and the packaging case 40, the sealing connection method of the partition 20 and the packaging case 40, in addition to heat sealing, can also choose glue connection, welding or sealing treatment of the metal and non-metal interface. .

In some embodiments of the present application, the electrochemical device 100 further includes an encapsulation material, and the encapsulation material covers a side of the bent portion 22 facing the first end surface 43 . Thus, the bent portion 22 can be sealed and connected with the first end surface 43 , so that the partition plate 20 is sealed and connected with the packaging case 40 , thus avoiding the existence of the outer edge of the first end surface 43 .

In some embodiments of the present application, as shown in FIG. 7 , the edge of the main body 21 and the edge of the bent portion 22 form an angled area 23, and the encapsulation material also covers the angled area 23 to ensure that the spacer 20 is separated and formed. The two cavities are independent, so that the electrolyte in each cavity is isolated from each other to prevent the electrolyte from leaking and causing the electrolyte to decompose and fail when it is charged at a high voltage.

Further, as shown in FIG. 7 , the bent portion 22 includes a short side a and a long side b, the main body 21 includes a first side c connected to the bent portion 22 , and the length of the long side b of the bent portion 22 is less than the side 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 and the extensions d of the bending portion 22 are respectively Two angled areas 23 (only one is shown in the figure) that are symmetrical in the longitudinal direction are formed. It should be noted that, depending on the materials of the separator 20 and the packaging case 40, the size of the angled area 23 will change. In this application, the size of the angled area 23 is not particularly limited. The angled area 23 in FIG. 7 It is only for illustration and does not limit the size. Those skilled in the art can choose the amount of encapsulation material according to the actual situation, as long as the encapsulation material can cover the two angled regions 23 to achieve the purpose of this application.

In some embodiments of the present application, as shown in FIG. 8 to FIG. 11 , the separator 20 further includes two side bending portions 24 located on both side edges of the main body portion 21 . Specifically, in some embodiments, the first end face 43 and the two side faces 45 of the packaging case 40 are integrally formed, that is, the packing case 40 is formed on the first end face 43 and the two side faces 45 (only one is shown in the figure). On the top, there is no sealing edge and no external folding edge. When the top sealing edge extending from the side of the tab 50 is not encapsulated, the separator 20 is inserted into the inside of the packaging case 40 through the top sealing edge, and the packaging material covers the side of the bent portion 22 facing the first end surface 43 and the two sides respectively. The side bending parts 24 are respectively facing one side of the two side surfaces 45, so that the bending part 22 is fitted and sealed to the first end surface 43, and the two side bending parts 24 are respectively fitted and sealed to the two side surfaces 45, The top edge 211 of the main body 21 is in sealing connection with the second end surface 44 . In this way, the partition 20 is sealed and connected with the packaging case 40 , so that the space inside the packaging case 40 is divided into two cavities. Thus, the existence of the first end surface 43 and the external folds of the two side surfaces 45 is avoided, and the volume of the electrochemical device 100 is further reduced, thereby improving the energy density of the electrochemical device 100 and effectively improving the packaging of the electrochemical device 100 reliability.

Further, when the partition plate 20 is sealed and connected with the packaging case 40 , the two side bending portions 24 are bent and respectively form a certain angle with the main body portion 21 . It should be noted that, according to the different materials of the partition plate 20 and the package case 40 , the included angles between the two side bending portions 24 and the main body portion 21 will also have the same or different changes. For example, the above-mentioned included angle is 70° to 110°. Preferably, the angle between the two side bent portions 24 and the main body is approximately 90°. At this time, the side bent portions 24 and the side surfaces 45 fit more compact, the packaging reliability of the electrochemical device 100 is higher.

Further, in order to ensure that the two cavities separated and formed by the separator 20 are independent, the joints between the bent portion 22 and the two side bent portions 24 are covered with packaging material, or the bent portion 22 and the two side bent The folded portion 24 is integrally formed by means of pre-pressing, and the corner area formed by the top edge 211 and the edges of the two side bent portions 24 is also covered with packaging material, thereby realizing the insulation effect of each cavity.

In some embodiments of the present application, the packaging material includes polypropylene, anhydride-modified polypropylene, polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid copolymer, ethylene-vinyl alcohol copolymer At least one of polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, epoxy resin, polyamide, polyester, amorphous α-olefin copolymer and its derivatives, etc. The use of the above packaging materials can more effectively improve the sealing performance, thereby improving the packaging reliability of the electrochemical device 100 . It should be noted that the present application has no special restrictions on the packaging temperature, packaging time and packaging pressure, as long as the purpose of the 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.

In some embodiments of the present application, as shown in FIGS. 2 to 3 , each electrode assembly 10 is provided with tabs 50 of different polarities, and the tabs 50 extend out of the packaging case 40 , and adjacent electrode assemblies 10 pass through the tabs. 50 connected in series. 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 case 40 without overlapping at all, and the adjacent first electrode assembly 11 and the second The electrode assembly 12 is connected in series through the first negative tab 52 and the second positive tab 53 , and the first positive tab 51 and the second negative tab 54 serve as positive and negative terminals for connection during charging and discharging. When the tabs 50 provided on each electrode assembly 10 are all extended out of the packaging shell 40 for welding, the welding effect of the tabs 50 can be monitored at any time, the risk of breaking the tabs 50 can be reduced, and the occurrence of problems caused by poor welding effects of the tabs 50 can be avoided. The problem of increased internal resistance of the electrochemical device 100 ; adjacent electrode assemblies 10 are connected in series can effectively increase the output voltage of the electrochemical device 100 .

Further, the first negative electrode tab 52 and the second positive electrode tab 53 connecting adjacent first electrode assemblies 11 and second electrode assemblies 12 in series may also extend out of the packaging case 40 at least partially overlapping.

In some embodiments of the present application, the separator has a thickness of 6 μm to 100 μm, preferably 10 μm to 40 μm, more preferably 20 μm to 30 μm. When the thickness of the separator is too thin (for example, less than 6 μm), the mechanical strength of the separator may be insufficient, which may easily cause damage and affect the performance or even safety of the electrochemical device; when the thickness of the separator is too thick (for example, greater than 100 μm), This increases the volume of the electrochemical device, thereby reducing the energy density of the electrochemical device.

In some embodiments of the present application, the material of the separator includes at least one of polymer film, metal foil or carbon material. The present application has no particular limitation on the type of the polymer film, as long as the purpose of the present application can be achieved. For example, polymer films may include polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate, polyether ether ketone, 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 ether, polysulfone, amorphous α-olefin copolymer and its derivatives At least one of the films. The present application has no particular limitation on the type of the metal foil material, as long as the purpose of the present application can be achieved. For example, metal foil materials may include 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 composition or alloy, etc. at least one. The present application has no particular limitation on the type of carbon material, as long as the purpose of the present application can be achieved. For example, the carbon material may include 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, etc. at least one.

Preferably, the material of the separator includes a polymer film, and the density of the polymer film is low, which can reduce the weight of the separator, thereby increasing the energy density of the lithium-ion battery. Moreover, under mechanical abuse (such as nailing, impact, extrusion, etc.), the polymer film has a smaller probability of generating debris, and has a better wrapping effect on mechanically damaged surfaces, which can improve the safety of the above-mentioned mechanical abuse. Performance, so that the safety test pass rate can be improved, and the safety performance of lithium-ion batteries can be further improved. Preferably, the material of the separator includes a metal foil material, which has strong isolation reliability, good toughness and compactness, and can be processed to be thinner, which can increase the energy density of the lithium-ion battery. Preferably, the material of the separator includes carbon material, which has excellent safety performance, good thermal conductivity and excellent high-temperature reliability. Preferably, the material of the separator includes a composite material composed of at least two of polymer film, metal foil or 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 Ni metal foil composite PP film, Ag metal foil composite PET film, polyurethane/stainless steel/polyurethane composite material or PP/Al/PP composite material, etc.

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.

The present application has no particular limitation on the type of the 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 polymer material and 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 0° to 30° from 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 realize electronic conduction. Another polymer conductive current collector has the same or different metal material layers on the two surfaces of the polymer material.

The present application has no particular limitation on the type of the 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 methods: spraying a polymer material on a stainless steel substrate to obtain a polymer material layer, heating the polymer material layer to soften it, implanting a one-dimensional or two-dimensional conductive material, and then spraying the polymer material again to form a high polymer material layer. Molecular material film, the polymer material film obtained by overheating roll pressing, the polymer material film is removed from the surface of the stainless steel substrate with a scraper, and the polymer material conductive current collector is obtained by winding. Polymer conductive current collectors can also be obtained by dispersing zero-dimensional conductive materials in polymer materials.

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.

In some embodiments of the present application, the first side of the bipolar separator is provided with an electrode active material layer, and the outermost layer of the electrode assembly adjacent to the electrode active material layer is provided with an electrode active material layer of opposite polarity. A diaphragm is arranged between the first side of the polar separator and the adjacent electrode assembly, the second side of the bipolar separator is electrically insulated from the adjacent electrode assembly, and a pole lug is drawn out from the bipolar separator. The lugs are connected in series with the electrode assemblies 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, which participates in the charging and discharging process of the lithium-ion battery and improves the energy density of the lithium-ion battery. A tab is led out from the bipolar separator, and the tab is connected to the tabs connected in series with the electrode assemblies on both sides, so as to provide a high output voltage.

In other embodiments of the present application, the first side of the bipolar separator is provided with an electrode active material layer, and the outermost layer of the electrode assembly adjacent to the electrode active material layer is provided with an electrode active material layer of opposite polarity, A separator is arranged 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 "electrical connection" means that the second side of the bipolar separator is physically connected to the outermost current collector of the adjacent electrode assembly, that is, there is no electrode on the surface of the electrode sheet electrically connected to the bipolar separator. active material.

Further, the bipolar separator may not lead out the tabs. At this time, the electrode assemblies on both sides of the bipolar separator are directly connected in series through the bipolar separator, and the lithium-ion battery can only lead out two electrodes with opposite polarities. Tabs, when the lithium-ion battery contains more than two electrode assemblies, all electrode assemblies are connected in series between the above two tabs with opposite polarities through bipolar separators.

Further, the bipolar separator can also lead out a tab, which is connected to the same polarity tab on the electrode assembly on the first side of the bipolar separator to form a parallel connection, and then connected to the electrode assembly on the second side. The tabs of opposite polarities are connected to form a series connection. At this time, the middle of the two electrode assemblies can be connected in series through the bipolar separator inside and outside through the tabs. In addition, the tabs of the bipolar separator may not be connected to the tabs of the electrode assembly, and are only used to monitor the voltage of the electrochemical device, which can promptly troubleshoot the electrode assembly, find the cause of failure, and improve the manufacturing efficiency of the electrochemical device. and production efficiency.

In some other embodiments of the present application, electrode active material layers of different polarities are respectively 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 with opposite polarity. The electrode active material layer of the bipolar separator is provided with a diaphragm between the electrode active material layer of the bipolar separator and the electrode active material layer of the outermost layer of the electrode assembly. The two sides of the bipolar separator are respectively provided with electrode active material layers with different polarities, and the two sides respectively form electrochemical units with the outermost electrode pole piece of the adjacent electrode assembly, so as to further increase the energy density of the lithium-ion battery.

The electrode assemblies on both sides of the bipolar separator can be connected in series directly through the bipolar separator, or can be connected in series internally and externally through the bipolar separator and two tabs with opposite polarities.

Further, the two sides of the bipolar separator are respectively provided with electrode active material layers with different polarities, and a tab is arranged on the bipolar separator, and the tab can be used to monitor the voltage of the electrochemical device, or the tab can be used to monitor the voltage of the electrochemical device. Insulation cladding. The tab can also be connected with the series tabs of the electrode assemblies on both sides of the bipolar separator.

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 wound structure or a laminated structure.

The present application has no special limitation on the material of the tab, as long as the purpose of the present application can be achieved. For example, the positive tab material includes at least one of aluminum (Al) or aluminum alloy, and the negative tab material includes at least one of nickel (Ni), copper (Cu) or nickel-plated copper (Ni—Cu). The present application has no special limitation on the welding method of the tabs, 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 limitation on the directions in which different tabs are drawn out, as long as the purpose of the present application can be achieved. For example, the directions in which the tabs are pulled out can be the same direction or different directions.

In the present application, the electrode assembly may include a separator, a positive electrode tab, and a negative electrode tab. The separator is used to separate the positive pole piece and the negative pole piece to prevent the internal short circuit of the electrochemical device, which allows the electrolyte ions to pass freely to complete the electrochemical charge and discharge process. The present application has no particular limitation on the number of separators, positive pole pieces and negative pole pieces, as long as the purpose of the present application can be achieved.

The present application has no particular limitation on the type of the separator, as long as the purpose of the present application can be achieved. For example, polyethylene (PE), polypropylene (PP)-based polyolefin (PO)-based separators, polyester films (such as polyethylene terephthalate (PET) films), cellulose films, polyimide films, etc. Amine film (PI), polyamide film (PA), spandex or aramid film, woven film, non-woven film (non-woven fabric), microporous film, composite film, separator paper, rolled film, spun film, etc. at least one of . For example, a separator may include a substrate layer and a surface treatment layer. The substrate layer can be a non-woven fabric, a film or a composite film with a porous structure, and the material of the substrate layer can include at least one of polyethylene, polypropylene, polyethylene terephthalate and polyimide, etc. kind. Optionally, a polypropylene porous film, a polyethylene porous film, a polypropylene non-woven fabric, a polyethylene non-woven fabric, or a polypropylene-polyethylene-polypropylene porous composite film may be used. Optionally, at least one surface of the substrate layer is provided with a surface treatment layer, and the surface treatment layer may be a polymer layer or an inorganic layer, or a layer formed by mixing a polymer and an inorganic material. For example, the inorganic layer includes inorganic particles and a binder, and the inorganic particles are not particularly limited, for example, they can be selected from aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium oxide, tin oxide, cerium oxide, nickel oxide , zinc oxide, calcium oxide, zirconia, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide and barium sulfate. The binder is not particularly limited, for example, it can be selected from polyvinylidene fluoride, a copolymer of vinylidene fluoride-hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, polyvinyl pyrene At least one of rolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene and polyhexafluoropropylene. The polymer layer comprises a polymer, and the polymer material includes polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride or poly( at least one of vinylidene fluoride-hexafluoropropylene) and the like.

The present application has no special limitation on the positive pole piece, as long as the purpose of the present application can be achieved. For example, a positive electrode sheet generally includes a positive electrode current collector and a positive electrode active material layer. Wherein, the positive electrode current collector is not particularly limited, as long as the purpose of the present application can be achieved. For example, aluminum foil, aluminum alloy foil, or a composite current collector may be included. The positive active material layer includes a positive active material. The type of positive electrode active material is not particularly limited, as long as the purpose of the application can be achieved, for example, it can include nickel-cobalt lithium manganate (811, 622, 523, 111), nickel-cobalt lithium aluminate, lithium iron phosphate, lithium-rich manganese At least one of base materials, lithium cobaltate, lithium manganate, lithium iron manganese phosphate, or lithium titanate. In the present application, there is no particular limitation on the thickness of the positive electrode current collector and the positive electrode active material layer, as long as the purpose 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, 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 is no particular limitation on the thickness of the positive electrode sheet, as long as the purpose of the 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, and the conductive layer 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 field. The conductive layer includes a conductive agent and a binder.

The present application has no special limitation on the negative electrode sheet, as long as the purpose of the present application can be achieved. For example, a negative electrode sheet generally includes a negative electrode current collector and a negative electrode active material layer. Among them, the negative electrode current collector is not particularly limited, as long as the purpose of the present application can be achieved, for example, it can include copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam or composite current collector. The negative active material layer includes a negative active material, a conductive agent, and a thickener. The type of negative electrode active material is not particularly limited, as long as the purpose of the present application can be achieved. For example, natural graphite, artificial graphite, mesophase microcarbon spheres (MCMB), hard carbon, soft carbon, silicon, silicon-carbon composite, SiO _x (0<x<2), Li-Sn alloy, Li- At least one of Sn—O alloy, Sn, SnO, SnO ₂ , lithium titanate Li ₄ Ti ₅ O ₁₂ with a spinel structure, Li—Al alloy, and metallic lithium. In the present application, there is no particular limitation on the thickness of the negative electrode current collector and the negative electrode active material layer, as long as the purpose of the application can be achieved, for example, the thickness of the negative electrode current collector is 6 μm to 10 μm, and the thickness of the negative electrode active material layer is 30 μm to 120 μm. In the present application, the thickness of the negative electrode sheet is not particularly limited, as long as the purpose of the application can be achieved, for example, the thickness of the negative electrode sheet is 50 μm to 150 μm. Optionally, the negative electrode sheet may further include a conductive layer, and the conductive layer 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 may be a commonly used conductive layer in the field. The conductive layer includes a conductive agent and a binder.

The present application has no special limitation on the conductive agent, as long as the purpose of the present application can be achieved. For example, the conductive agent can include 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. at least one. The present application has no special limitation on the binder, as long as the purpose of the present application can be achieved. For example, the binder may include polyacryl alcohol, sodium polyacrylate, potassium polyacrylate, lithium polyacrylate, polyimide, polyimide, polyamideimide, 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 carboxymethyl At least one of base cellulose sodium (CMC-Na) and the like.

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.

The present application has no particular limitation on the electrolyte solution, as long as the purpose of the present application can be achieved. For example, an electrolyte typically includes a lithium salt and a non-aqueous solvent. In some embodiments of the present application, lithium salts may include LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiClO ₄ , LiB(C ₆ H ₅ ) ₄ , LiCH ₃ SO ₃ , LiCF ₃ SO ₃ , LiN(SO ₂ CF ₃ ) _2. At least one of LiC(SO ₂ CF ₃ ) ₃ , LiSiF ₆ , LiBOB, or lithium difluoroborate. For example, LiPF ₆ may be selected as a lithium salt because it can give high ion conductivity and improve cycle characteristics. The non-aqueous solvent may be at least one of carbonate compounds, carboxylate compounds, ether compounds or other organic solvents. The carbonate compound may be at least one of a chain carbonate compound, a cyclic carbonate compound, or a fluorocarbonate compound. Chain carbonate compounds may include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC) or methyl ethyl carbonate At least one of ester (MEC) and the like. The cyclic carbonate compound may include at least one of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinyl ethylene carbonate (VEC), and the like. Fluorocarbonate compounds may include fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate ester, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-difluorocarbonate - at least one of 1-methylethylene carbonate, 1,1,2-trifluoro-2-methylethylene carbonate, or trifluoromethylethylene carbonate. Carboxylate compounds may include methyl formate, methyl acetate, ethyl acetate, n-propyl acetate, t-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, gamma-butyrolactone, decyl At least one of lactone, valerolactone, mevalonolactone, or caprolactone. Ether compounds may include dibutyl ether, tetraglyme, diglyme, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxy at least one of ethane, 2-methyltetrahydrofuran, or tetrahydrofuran. The above-mentioned other organic solvents may include dimethyl sulfoxide, 1,2-dioxolane, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, methyl At least one of amide, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, trioctyl phosphate or phosphoric acid ester.

The present application has no special limitation on the packaging shell, as long as the purpose of the present application can be achieved. For example, the packaging shell can include an inner layer and an outer layer, and the inner layer is hermetically connected with the partition, so the material of the inner layer can include a polymer material to achieve a good sealing effect; at the same time, the combination of the inner layer and the outer layer can effectively protect Internal structure of an electrochemical device. Specifically, the material of the inner layer includes at least one of polypropylene, polyester, p-hydroxybenzaldehyde, polyamide, polyphenylene ether, polyurethane, and the like. In this application, there is no particular limitation on the material of the outer layer, as long as the purpose of this 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 and the like. In addition, the packaging shell can also be an aluminum-plastic film, and the aluminum-plastic film includes a nylon layer, an aluminum foil layer and a PP layer. The packaging shell can also be a steel shell after insulation treatment.

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 packaging shell may have a thickness of 50 μm to 500 μm, preferably 50 μm to 300 μm, more preferably 50 μm to 200 μm. The packaging case within the above thickness range can effectively protect the internal structure of the electrochemical device.

In this application, there is no particular limitation on the size of the sealing edge, as long as the purpose of this application can be achieved. For example, the thickness T (unit: mm) and width W (unit: mm) of the sealing edge satisfy 0.01≦T/W≦0.05. If the ratio of T/W is within the above range, the battery can be well sealed and the service life of the battery can be improved. When the T/W is too small, the thickness of the seal may be insufficient, and the sealing effect may be poor, resulting in a decrease in the environmental stability of the battery. The service life of the battery; if the ratio of T/W is too large, the seal width W may be too small, and the sealing effect is also poor, resulting in a decrease in the environmental stability of the battery. For example, water vapor in the environment can easily penetrate into the battery, resulting in Increased content, electrolyte decomposition and other problems will reduce 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 1 mm to 7 mm. It should be noted that during the encapsulation process, the polymer material in the packaging shell and the encapsulation material are heat-pressed and sealed together. Therefore, the thickness of the seal includes the thickness of the packaging material after it is fused with the inner polymer material of the packaging shell. The seal width refers to the width of the sealing area formed by the combination of the packaging material and the inner polymer material of the packaging shell after heat-press sealing.

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

The present application has no special limitation on the preparation process of the electrochemical device, as long as the purpose of the present application can be achieved. For example, an electrochemical device can be prepared by the following process: overlapping the positive and negative pole pieces through a separator, winding or folding them as required, putting them into the case, injecting the electrolyte into the case and sealing it. In addition, anti-overcurrent elements, guide plates, etc. can also be placed in the casing as needed, so as to prevent pressure rise and overcharge and discharge inside the electrochemical device.

In the electrochemical device provided by the present application, the side wall of the first recess and the side wall of the second recess are integrally formed to form the first end face, and one edge of the separator is sealed and connected to the first end face, reducing the risk of The loss of energy density caused by the external folding of the end face effectively improves the energy density of the electrochemical device. Moreover, there is no external folded edge of the first end face, the risk of package failure of the electrochemical device is reduced, and the safety performance of the electrochemical device is further improved. At the same time, the production cost of the electrochemical device can be significantly reduced.

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; both the first electrode assembly and the second electrode assembly are wound structures; the separator is PP/Al/PP composite separator, the thickness of each layer is 30μm, that is, the thickness of the separator is 90μm, the separator includes a main part and a bent part, and the angle between the bent part and the main part is 90°. The bending part is attached to the first end surface of the packaging shell and the PP layer on the surface of the partition and the PP layer of the aluminum-plastic film are heat-sealed to realize the airtight connection, and the corner area is sealed by dripping the packaging material epoxy resin. The sealing edge of the first end surface and the second end surface and the sealing edges of both sides are sealed and connected through the PP layer on the surface of the separator and the PP layer inside the packaging shell. The packaging temperature is 190°C, the packaging time is 3s, and the packaging pressure is 0.4MPa. Physical isolation of the first electrode assembly 11 and the second electrode assembly 12 is achieved.

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 treatment; the first electrode assembly and the second electrode assembly are both laminated structures; the separator is polyurethane/ Stainless steel/polyurethane composite separator, the thickness of the three-layer material is 1μm/10μm/1μm, that is, the thickness of the separator is 12μm, the separator includes a main part and a bent part, and the angle between the bent part and the main part 90°, the bending part is attached to the first end surface of the packaging shell, and the polyurethane layer on the surface of the partition and the polyurethane layer on the inner surface of the steel shell are heat-sealed to realize the airtight connection, and the corner area is sealed by applying the packaging material polyurethane. The main body and the packaging case are hermetically connected by the packaging material, the packaging temperature is 190°C, the packaging time is 3s, and the packaging pressure is 0.4MPa, so that the physical isolation of the first electrode assembly 11 and the second electrode assembly 12 is realized.

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

The electronic device of the present application is not particularly limited, and it may include but not limited to: notebook computers, pen-input computers, mobile computers, electronic book players, portable phones, portable fax machines, portable copiers, portable printers, headsets, VCRs, LCD TVs, portable cleaners, portable CD players, mini discs, transceivers, electronic organizers, calculators, memory cards, portable tape recorders, radios, backup power supplies, motors, cars, motorcycles, power-assisted bicycles, bicycles, Lighting appliances, toys, game consoles, clocks, electric tools, flashlights, cameras, large household storage batteries and lithium-ion capacitors, etc.

It should be noted that in this article, relational terms such as "first" and "second" are only used to distinguish one entity from another, and do not necessarily require or imply that there is a relationship between these entities. Any such actual relationship or sequence. Moreover, the term "comprises", "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion such that an article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, Or also include elements inherent in the article or device.

Each embodiment in this specification is described in a related manner, the same and similar parts of each embodiment can be referred to each other, and each embodiment focuses on the differences from other embodiments.

The above descriptions are only preferred embodiments of the application, and are not intended to limit the application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the application shall be included in the protection of the application. within the range.

Claims

An electrochemical device, comprising a packaging case, a separator, and electrode assemblies respectively arranged on both sides of the separator, each electrode assembly is provided with tabs, and it is characterized in that the packaging case is arranged on both sides of the separator. The sides are respectively provided with a first recess and a second recess, and the side wall of the first recess is integrally formed with the side wall of the second recess to form the first end surface of the packaging shell; the packing shell also includes The second end face opposite to the first end face and the two side faces connected between the first end face and the second end face and opposite to each other, the tabs extend out of the second end face; the spacer The plate is sealed and connected to the first end surface, the second end surface and the two side surfaces, thereby dividing the space inside the packaging shell into two cavities, each cavity is packaged with the electrode assembly and electrolyte .
The electrochemical device according to claim 1, wherein the separator comprises a main body and a bent part located at one edge of the main body, and the bent part extends into the first concave part or the first concave part. The second concave portion, the bent portion is in contact with the first end surface and is in sealing connection; the remaining edges of the main body are in sealing connection with the second end surface and the two side surfaces respectively.
The electrochemical device according to claim 1, further comprising an encapsulation material covering at least peripheries of two surfaces of the separator.
The electrochemical device according to claim 2, characterized in that the electrochemical device further comprises an encapsulation material, and the encapsulation material covers a side of the bent portion facing the first end face.
The electrochemical device according to claim 4, wherein the edge of the main body part and the edge of the bent part form an angled area, and the packaging material also covers the angled area.
The electrochemical device according to any one of claims 3 to 5, wherein the packaging material comprises 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 at least one of the derivatives.
The electrochemical device according to claim 1, wherein each of the electrode assemblies is provided with tabs of different polarities, the tabs extend out of the packaging shell, and adjacent electrode assemblies pass through the The tabs are connected in series.
The electrochemical device according to claim 1, wherein the separator has a thickness of 6 μm to 100 μm.
The electrochemical device according to claim 1, wherein the material of the separator comprises at least one of polymer film, metal foil or carbon material.
An electronic device, characterized by comprising the electrochemical device according to any one of claims 1-9.