CN115461909A

CN115461909A - Electrochemical device and electronic device comprising same

Info

Publication number: CN115461909A
Application number: CN202080100167.9A
Authority: CN
Inventors: 张楠; 张益博; 严坤; 胡乔舒
Original assignee: Ningde Amperex Technology Ltd
Current assignee: Ningde Amperex Technology Ltd
Priority date: 2020-06-30
Filing date: 2020-06-30
Publication date: 2022-12-09
Also published as: WO2022000307A1

Abstract

An electrochemical device and an electronic device including the same. The electrochemical device comprises at least one bipolar current collector (10), wherein the bipolar current collector (10) is hermetically connected with an outer package (20), independent sealed cavities are formed on two sides of the bipolar current collector (10), each sealed cavity comprises an electrode assembly (30) and electrolyte, one side of the bipolar current collector (10) is electrically connected with the outermost positive pole piece of the adjacent electrode assembly (30), and the other side of the bipolar current collector (10) is electrically connected with the outermost negative pole piece of the adjacent electrode assembly (30). Through the introduction of the bipolar current collector (10) and the sealing design of the bipolar current collector (10) and the inner layer of the outer package (20), the ionic insulation between the multiple electrode assemblies (30) of the liquid series battery is realized among the multiple electrode assemblies (30), so that the use reliability of the high-output voltage battery and the effective output of electric energy are realized.

Description

Electrochemical device and electronic device comprising same

Technical Field

The present disclosure relates to the field of electrochemistry, and more particularly, to an electrochemical device and an electronic device including the same.

Background

Lithium ion batteries have many advantages of high energy density, long cycle life, high nominal voltage, low self-discharge rate, small volume, light weight, etc., and have wide applications in the consumer electronics field. With the rapid development of Electric Vehicles (EVs) and mobile electronic devices in recent years, people have increasingly high requirements on energy density, safety, cycle performance and other related requirements of batteries, and the appearance of novel lithium ion batteries with overall improved comprehensive performance is expected.

In the existing lithium ion battery system, the working voltage of the lithium ion battery is difficult to exceed 5V due to the limitation of an electrochemical system, such as limited voltage difference of anode and cathode materials, limited oxidation and reduction resistance of electrolyte, and the like. In actual use, however, there are many occasions where voltages exceeding 5V are required, such as Electric Vehicles (EV), voltage transformers (PT), energy Storage Systems (ESS), and the like. Even in the mobile phone market, in order to meet the requirements of fast charging and the like, the open-circuit voltage of the lithium ion battery needs to be increased.

At present, some companies propose a concept of series battery to solve this problem, and the scheme is to directly connect two lithium ion batteries in series in the same packaging bag, but the following problems generally exist: on one hand, the two lithium ion batteries connected in series are not subjected to ion insulation, and under the condition that the voltage of the batteries is increased, the electrolyte is decomposed under the condition of high voltage, so that the batteries are failed, and meanwhile, the two lithium ion batteries are subjected to internal short circuit due to the voltage difference of pole pieces, and the batteries are also failed; on the other hand, this series connection mode need weld different lithium ion battery's different polarity utmost point ear in order to realize lithium ion battery's series connection, and the not good lithium ion battery internal resistance that easily leads to of utmost point ear welding effect increases the scheduling problem, not only has very big potential safety hazard but also is unfavorable for the output of electric energy, and simultaneously, the design of piece is drawn forth to a plurality of utmost point ears can increase the fracture risk of utmost point ear to reduce the production goodness. Therefore, developing a new lithium ion battery with a series structure to achieve the reliability of the high-output voltage battery and the effective output of the electric energy becomes a problem to be solved by those skilled in the art.

Disclosure of Invention

An electrochemical device and an electronic device including the same are provided to achieve high output voltage battery use reliability and efficient output of electric energy.

The first aspect of the present application provides an electrochemical device, which includes a bipolar current collector and electrode assemblies, wherein the electrode assemblies are located on two sides of the bipolar current collector, and the polarities of the electrode assemblies on the two sides, which are close to the outermost pole pieces of the bipolar current collector, are different.

In some embodiments of the present application, one side of the bipolar current collector is electrically connected to the outermost positive electrode sheet of the electrode assembly adjacent thereto, and the other side of the bipolar current collector is electrically connected to the outermost negative electrode sheet of the electrode assembly adjacent thereto.

In some embodiments of the present application, the bipolar current collector is connected to an external package, and separate sealed cavities are formed on two sides of the bipolar current collector, and each sealed cavity contains one electrode assembly and electrolyte.

In some embodiments of the present application, the electrolyte includes an organic solvent.

In some embodiments of the present application, the bipolar current collector further comprises a sealing region, the sealing region being in sealing connection with an overwrap, the sealing region comprising a sealing material, the sealing material having a melting point of 100 ℃ to 200 ℃.

In some embodiments of the present application, the material of the bipolar current collector comprises at least one of a Cu-Al composite current collector, a stainless steel foil current collector, or a polymeric conductive current collector;

the sealing material comprises at least one of polypropylene (PP), polyester or p-hydroxybenzaldehyde (PHBA).

In some embodiments of the present application, the bipolar current collector has an electron resistivity in the Z-direction of 1 × 10 ^- ¹¹ Omega cm to 30 omega cm.

In some embodiments of the present application, the bipolar current collector has a water permeability M ≦ 10 ^-3 g/(day·m ² ·Pa·3mm)。

In some embodiments of the present application, the bipolar current collector has a thickness of 2 μm to 100 μm.

In some embodiments of the present application, where the bipolar current collector is connected to the outer package, the seal thickness T and the seal width W satisfy T/W ≦ 0.05, where T and W are in mm.

In some embodiments of the present application, the electrochemical device has at least one of the following features:

a. the electrochemical device comprises 2 to 3 bipolar current collectors;

b. the melting point of the sealing material is 110-180 ℃;

c. the Z-direction electron resistivity of the bipolar current collector is 1 × 10 ^-5 Omega cm to 5 omega cm;

d. the water permeability M of the bipolar current collector is less than or equal to 10 ^-4 g/(day·m ² ·Pa·3mm)；

e. The bipolar current collector has a thickness of 5 to 50 μm;

f. the seal thickness T and the seal width W meet the condition that T/W is more than or equal to 0.02 and less than or equal to 0.04.

1) The melting point of the sealing material is from 120 ℃ to 160 ℃;

2) The bipolar current collector has an electron resistivity in the Z direction of 0.01 Ω · cm to 0.10 Ω · cm;

3) The bipolar current collector has a thickness of 5 to 20 μm.

In some embodiments of the present application, the structure of the electrode assembly includes at least one of a winding structure or a lamination structure.

In a second aspect, an electronic device is provided that includes the electrochemical device provided in the first aspect of the present application.

The application provides an electrochemical device, through bipolar mass flow body's introduction and bipolar mass flow body all around with the sealed design of extranal packing inlayer, split into a plurality of independent seal chamber with the battery, realize the ionic insulation between liquid series battery multiple electrode assembly between a plurality of electrode subassemblies, the potential safety hazard of short circuit or electrolyte high pressure decomposition in avoiding taking place to improve electrochemical device's security performance, guaranteed the effectual electric energy output of high voltage battery. In addition, through the design of different electrode component structures and bipolar current collectors, the internal series connection of the electrode components is realized, the structural design of series connection is realized without welding lugs among a plurality of electrode components, the process is simplified, the production efficiency is improved, meanwhile, the problem of poor series connection of electrochemical devices caused by welding is avoided, the manufacturing reliability of the electrochemical devices is greatly improved, and the output of electric energy is facilitated. In addition, the energy density of the high-output voltage battery is effectively improved by reducing the number of the lugs.

Drawings

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 the embodiments and the prior art, and obviously, the drawings in the following description are only some embodiments of the present application, and other embodiments can be obtained by those skilled in the art according to the drawings.

Fig. 1 is a schematic structural view of an electrochemical device according to an embodiment of the present application.

Fig. 2 is an exploded structural view of the electrochemical device of fig. 1.

Fig. 3 is a schematic cross-sectional view of a tandem electrode assembly according to an embodiment of the present application.

Fig. 4 is a front view of an electrochemical device according to an embodiment of the present application.

Fig. 5 is a top view of an electrochemical device according to an embodiment of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It is to be understood that the embodiments described are only a few embodiments of the present application and not all embodiments. All other embodiments obtained based on the embodiments in the present application belong to the protection scope of the present application.

The electrochemical device described herein is not particularly limited, and may be any electrochemical device that can use the present disclosure, such as a lithium ion battery, a sodium ion battery, a magnesium ion battery, a supercapacitor, and the like. For convenience of description, the following description will be made by taking a lithium ion battery as an example, but this does not mean that the electrochemical device of the present application is limited to a lithium ion battery.

The first aspect of the present application provides an electrochemical device, it contains bipolar mass flow body and electrode subassembly, electrode subassembly is located bipolar mass flow body's both sides, and both sides electrode subassembly is close to respectively bipolar mass flow body's the polarity of outmost pole piece is different, bipolar mass flow body's one side is connected with the outmost positive pole piece electricity of its adjacent electrode subassembly, bipolar mass flow body's opposite side is connected with the outmost negative pole piece electricity of its adjacent electrode subassembly.

Fig. 2 shows an embodiment of the present application, wherein the electrode assemblies 30 are located on two sides of the bipolar current collector 10, and the polarities of the electrode assemblies 30 on the two sides near the outermost pole pieces of the bipolar current collector 10 are different, one side of the bipolar current collector 10 is electrically connected to the outermost positive pole piece of the electrode assembly 30 adjacent to the bipolar current collector 10, and the other side of the bipolar current collector 10 is electrically connected to the outermost negative pole piece of the electrode assembly 30 adjacent to the bipolar current collector.

In the present application, the above-mentioned "electrically connecting" includes that the current collector of the positive electrode plate or the negative electrode plate respectively realizes circuit connection by physically contacting with one side of the bipolar current collector or by physically contacting with one side of the bipolar current collector a conductive sheet, that is, the surface of the electrode plate electrically connected with the bipolar current collector has no electrode active material.

In some embodiments of the present application, the specific number of bipolar current collectors included in the electrochemical device is not limited, and those skilled in the art can select the bipolar current collectors according to actual needs as long as the purpose of the present application can be achieved, for example, 2 to 3 bipolar current collectors are included. And electrode assemblies are arranged on two sides of the bipolar current collector.

In some embodiments of the present application, the bipolar current collector is hermetically connected to an external package, and separate sealed cavities are formed on two sides of the bipolar current collector, and each sealed cavity encloses one electrode assembly and one electrolyte. Fig. 1 shows an embodiment of the present application, wherein the bipolar current collector 10 is hermetically connected to an external package 20, and separate sealed cavities are formed on two sides of the bipolar current collector 10, and each sealed cavity contains one electrode assembly 30 and electrolyte.

In the present application, the above-mentioned "outer package" generally refers to an aluminum plastic film comprising a nylon layer, an aluminum foil layer and a PP layer, and the thickness of the aluminum plastic film may be 60 μm to 500 μm, preferably 60 μm to 300 μm, and more preferably 60 μm to 200 μm.

In some embodiments of the present application, the electrode assembly may include a separator for separating the positive electrode sheet and the negative electrode sheet, preventing internal short circuit of the electrochemical device, allowing free passage of electrolyte ions, and completing the electrochemical charging and discharging process. In the present application, the number of the separator, the positive electrode sheet, and the negative electrode sheet is not particularly limited as long as the object of the present application can be achieved.

In some embodiments of the present application, the separator is not particularly limited as long as the object of the present application can be achieved, and any separator known in the art may be used. For example, at least one of Polyolefin (PO) type separators mainly composed of Polyethylene (PE) and polypropylene (PP), polyester films (for example, polyethylene terephthalate (PET) films), cellulose films, polyimide films (PI), polyamide films (PA), spandex or aramid films, woven films, nonwoven films (nonwoven fabrics), microporous films, composite films, separator papers, rolled films, and spun films.

The separator may include a substrate layer and a surface treatment layer. The substrate layer may be a nonwoven fabric, a film or a composite film having a porous structure, and the material of the substrate layer may be at least one selected from polyethylene, polypropylene, polyethylene terephthalate, polyimide, and the like. Optionally, a polypropylene porous film, a polyethylene porous film, a polypropylene nonwoven fabric, a polyethylene nonwoven fabric, or a polypropylene-polyethylene-polypropylene porous composite film may be used. Optionally, a surface treatment layer is disposed on at least one surface of the substrate 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 substance.

For example, the inorganic layer includes inorganic particles and a binder, and the inorganic particles are not particularly limited and may be, for example, at least one selected from alumina, silica, magnesia, titania, hafnia, tin oxide, ceria, nickel oxide, zinc oxide, calcium oxide, zirconia, yttria, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, barium sulfate, and the like. The binder is not particularly limited, and may be, for example, one or a combination of several selected from polyvinylidene fluoride, a copolymer of vinylidene fluoride-hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, polyhexafluoropropylene, and the like. The polymer layer contains a polymer, and the material of the polymer comprises at least one of polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride, poly (vinylidene fluoride-hexafluoropropylene), and the like.

In some embodiments of the present application, the positive electrode sheet is not particularly limited as long as the object 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. The positive electrode current collector is not particularly limited, and may be any positive electrode current collector known in the art, such as an aluminum foil, an aluminum alloy foil, or a composite current collector. The positive electrode active material is not particularly limited, and may be any positive electrode active material known in the art, and for example, may include at least one of NCM811, NCM622, NCM523, NCM111, NCA, lithium iron phosphate, lithium cobaltate, lithium manganate, lithium iron manganese phosphate, lithium titanate, and the like.

Optionally, the positive electrode sheet may further include a conductive layer between the positive electrode current collector and the positive electrode active material. The composition of the conductive layer is not particularly limited, and may be a conductive layer commonly used in the art. For example, the conductive layer includes a conductive agent and a binder.

In some embodiments of the present application, the negative electrode tab is not particularly limited as long as the object of the present application can be achieved. For example, the negative electrode tab typically includes a negative electrode current collector and a negative electrode active material. The negative electrode current collector is not particularly limited, and may be any negative electrode current collector known in the art, such as a copper foil, a copper alloy foil, or a composite current collector. The anode active material is not particularly limited and may be any anode active material known in the art. For example, at least one of graphite, hard carbon, soft carbon, silicon carbon, silicon oxide, or the like may be included.

Optionally, the negative electrode tab may further comprise a conductive layer located between the negative current collector and the negative active material. The composition of the conductive layer is not particularly limited, and may be a conductive layer commonly used in the art. For example, the conductive layer includes a conductive agent and a binder.

The above-mentioned conductive agent is not particularly limited, and any conductive agent known in the art may be used as long as the object 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 fibers, graphene, or the like. For example, conductive carbon black (Super P) can be used as the conductive agent. The adhesive is not particularly limited, and any adhesive known in the art may be used as long as the object of the present invention is achieved. For example, the binder may include at least one of Styrene Butadiene Rubber (SBR), polyvinyl alcohol (PVA), polytetrafluoroethylene (PTFE), sodium carboxymethylcellulose (CMC-Na), or the like. For example, styrene Butadiene Rubber (SBR) may be used as the binder.

In the present application, the electrolyte is not particularly limited, and an electrolyte known to those skilled in the art may be used, for example, the electrolyte is selected from any one of a gel state, a solid state, and a liquid state. For example, the liquid electrolyte includes a lithium salt and a nonaqueous solvent.

The lithium salt is not particularly limited, and any lithium salt known in the art may be used as long as the object of the present application can be achieved. For example, the lithium salt 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 、LiC(SO ₂ CF ₃ ) ₃ Or LiPO ₂ F ₂ And the like. For example, liPF is used as lithium salt ₆ 。

The nonaqueous solvent is not particularly limited as long as the object of the present application can be achieved. For example, the nonaqueous solvent may include at least one of a carbonate compound, a carboxylate compound, an ether compound, a nitrile compound, or other organic solvents, etc.

For example, the carbonate compound may include at least one of diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), methylethyl carbonate (MEC), ethylene Carbonate (EC), propylene Carbonate (PC), butylene Carbonate (BC), vinyl Ethylene Carbonate (VEC), 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 trifluoromethyl ethylene carbonate, and the like.

In some embodiments of the present application, the bipolar current collector is hermetically connected to the outer package, and the adjacent electrode assemblies and the electrolyte are completely separated by the bipolar current collector, so that each is in an independent sealed cavity, and ionic isolation is achieved between different cavities. Two sides of the same bipolar current collector are respectively and electrically connected with adjacent electrode assemblies, wherein one side of the bipolar current collector is electrically connected with the outermost positive pole piece of the adjacent electrode assembly, and the electrically connected side of the positive pole piece is free of electrode active materials; the other side of the bipolar current collector is electrically connected with the outermost negative pole piece of the electrode assembly adjacent to the bipolar current collector, and the side, which is electrically connected with the negative pole piece, is free of electrode active materials.

Fig. 3 is a schematic cross-sectional structure of a tandem electrode assembly according to an embodiment of the present disclosure, as shown in fig. 3, a first electrode assembly 31 is disposed on a lower side of a bipolar current collector 10, and a second electrode assembly 32 is disposed on an upper side of the bipolar current collector 10, where the two electrode assemblies include a positive electrode current collector 61, a positive electrode active material 71, a negative electrode current collector 62, a negative electrode active material 72, and a separator 80, the bipolar current collector 10 is disposed on the first electrode assembly 31, and one side of the bipolar current collector 10 is electrically connected to the negative electrode current collector 62 on the uppermost layer of the first electrode assembly 31, and one side of the negative electrode current collector 62 connected to the bipolar current collector 10 is free of the negative electrode active material 72; the second electrode assembly 32 is placed on the bipolar current collector 10 with the lowermost positive current collector 61 electrically connected to the other side of the bipolar current collector 10, and the side of the positive current collector 61 connected to the bipolar current collector 10 is free of the positive active material 71.

The design of the internal series structure avoids the problem that the electrode components are connected in series badly due to welding when the processes are simplified and the production efficiency is improved, greatly improves the manufacturing reliability of the battery, is beneficial to the output of electric energy, and effectively improves the energy density of the high-output voltage battery due to the reduction of the number of the electrode lugs.

In some embodiments of the present application, the bipolar current collector further comprises a sealing region in sealed connection with an overwrap, the sealing region further comprising a sealing material comprising at least one of polypropylene (PP), polyester, or para-hydroxybenzaldehyde (PHBA), the sealing material having a melting point of 100 to 200 ℃, preferably 110 to 180 ℃, more preferably 120 to 160 ℃.

The outer contour sealing area is hermetically connected with the outer package, specifically, the periphery of the bipolar current collector is compounded with a fusible sealing material and is subjected to heat sealing with the inner layer of the outer package at the temperature of 100-200 ℃, so that independent sealing cavities are formed in the electrochemical device, ion insulation among multiple electrode assemblies of the liquid series battery is realized among multiple electrode assemblies, the potential safety hazard of internal short circuit or electrolyte high-pressure decomposition is avoided, and the safety performance of the electrochemical device is improved.

In some embodiments of the present application, the material of the bipolar current collector comprises at least one of a Cu-Al composite current collector, a stainless steel foil current collector, or a polymeric conductive current collector. The bipolar current collector has good conductivity in the thickness direction (hereinafter referred to as the Z direction), for example, the electron resistivity of the bipolar current collector in the Z direction is 1 × 10 ^-11 To 30. Omega. Cm, preferably 1X 10 ^-5 To 5 Ω · cm, more preferably 0.01 to 0.10 Ω · cm.

The polymer conductive current collector comprises a composite material of a polymer material and a conductive material, and the polymer conductive current collector is not particularly limited in the application as long as the object of the present invention can be achieved, for example, the polymer conductive current collector comprises a polymer matrix and a conductive agent, wherein the conductive agent is a one-dimensional or two-dimensional conductive material, and the conductive material is distributed in the polymer matrix in a direction forming an angle of 0 to 30 degrees with the thickness direction of the polymer matrix. Another kind of polymer current collector contains the conducting layer that sets up respectively on two surfaces of polymer matrix, connects between two conducting layers. The other polymer conductive current collector comprises a porous polymer matrix, and conductive materials are positioned in pores of the porous polymer matrix, so that the two surfaces of the polymer conductive current collector are in electronic conduction.

The method for preparing the polymeric conductive current collector is not particularly limited as long as the object of the present invention can be achieved, and for example, the polymeric conductive current collector can be obtained by the following method: spraying a high polymer material on a stainless steel substrate to obtain a high polymer material layer, heating the high polymer material layer to soften the high polymer material layer, implanting a one-dimensional or two-dimensional conductive material, then spraying the high polymer material again to form a high polymer material film, carrying out hot rolling on the obtained high polymer material film, taking down the high polymer material film from the surface of the stainless steel substrate by using a scraper, and rolling to obtain the high polymer conductive current collector.

The polymer film includes polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate, polyetheretherketone, polyimide, polyamide, polyethylene glycol, polyamideimide, polycarbonate, cyclic polyolefin, 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, polyethylene, polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, polyphenylene oxide, polysulfone, or at least one of derivatives thereof.

The conductive material includes at least one of a carbon material or a metal material.

The carbon material may include at least one of a single-walled carbon nanotube, a multi-walled carbon nanotube (MWCNT), a conductive carbon fiber, a conductive carbon black, a fullerene, a conductive graphite, or graphene.

Wherein the metal material may include at least one of Cu, al, ni, ti, ag, au, pt, or stainless steel and alloys thereof.

The polymeric conductive current collector may also be formed by other methods. For example, conductive agent particles or the like are dispersed in a polymer material.

In some embodiments of the present application, the bipolar current collector has a water permeability M ≦ 10 ^-3 g/(day·m ² Pa.3 mm), preferably M.ltoreq.10 ^-4 g/(day·m ² Pa.3 mm) to avoid the water content exceeding the standard in the service life of the lithium ion battery after the lithium ion battery is packaged.

In some embodiments of the present application, the bipolar current collector has a thickness of 2 μm to 100 μm, preferably 5 μm to 50 μm, and more preferably 5 to 20 μm. When the thickness of the bipolar current collector is less than 2 μm, the mechanical strength of the bipolar current collector may be insufficient; when the thickness thereof is more than 100 μm, the mass of the introduced inactive material increases, reducing the energy density of the lithium ion battery.

In some embodiments of the present application, where the bipolar current collector is connected to the outer package, the seal thickness T and the seal width W satisfy T/W ≦ 0.05, preferably 0.02 ≦ T/W ≦ 0.04.

In the present application, the term "seal" refers to a sealed region of an overwrap. For example, fig. 4 is a front view of an embodiment of the present application, the thickness T of the seal area 40 of the overwrap, i.e., the seal thickness T; fig. 5 is a plan view of an embodiment of the present invention, showing a seal width W which is a width W of the seal region 40 of the exterior package. When T/W is not more than 0.05, excellent packaging reliability can be achieved, otherwise, the packaging effect may be reduced due to the inappropriate seal thickness and seal width. In the present application, the seal width and the seal thickness are not particularly limited as long as the ratio satisfies requirements, and those skilled in the art can select them according to the specific battery size, for example, the seal width is preferably 1mm to 7mm.

In the present application, the type of the electrode assembly is not particularly limited, and may include at least one of a winding structure or a lamination structure, for example.

In some embodiments of the present application, the electrode assembly has a structure including a winding structure, and at least one positive electrode tab and one negative electrode tab are respectively led out from a positive electrode tab and a negative electrode tab of the electrode assembly.

In some embodiments of the present application, the electrode assembly is a laminated structure, the electrode assembly includes a plurality of tabs, a positive tab and a negative tab are respectively led out from each layer of positive electrode sheet and negative electrode sheet, and finally the electrode assembly of the laminated structure includes a plurality of groups of positive tabs and negative tabs, and then the tabs are transferred by transfer welding to lead out the metal sheets.

In the present application, the welding method of the tab is not particularly limited as long as the object of the present application can be achieved. For example, at least one of laser welding, ultrasonic welding, or resistance welding, etc.

In some embodiments of the present application, the bipolar current collector may or may not have a tab lead out, and may be used to monitor the voltage of a single electrode assembly as the bipolar current collector leads out the tab.

In the present application, the direction in which the tab is drawn out is not particularly limited as long as the object of the present application can be achieved. For example, the direction of the tab lead-out can be the same direction or different directions.

In a second aspect, an electronic device is provided that includes an electrochemical device provided in the first aspect of the present application.

The electronic device described in the present application includes electronic devices in general in the field, such as a notebook computer, a mobile phone, an electric motorcycle, an electric automobile, an electric toy, an energy storage system, an unmanned aerial vehicle, an electric tool, a floor sweeping robot, a tablet computer, a power grid, an electric boat, and the like.

Terms used in the art are generally terms commonly used by those skilled in the art, and if they are inconsistent with commonly used terms, the terms in this application control.

The test method comprises the following steps:

the output voltage testing method comprises the following steps:

in testing the output voltage of comparative example 1, the test temperature was 25 ± 3 ℃, the lithium ion battery was charged to 4.2V at a constant current of 0.5C, and then charged to a current of 0.05C at a constant voltage of 4.2V, left for 1 hour, and the open circuit voltage was measured.

In testing the output voltages of comparative examples 2 to 3 and examples 1 to 25, the test temperature was 25 ± 3 ℃, and the lithium ion battery was charged to 8.4V at a constant current of 0.5C, then charged to a current of 0.05C at a constant voltage of 8.4V, left to stand for 1 hour, and the open circuit voltage was measured.

Discharge capacity after 50 charge-discharge cycles (cycles)/first discharge capacity η test method:

in the test of comparative example 1, the test temperature is 25 ± 3 ℃, the lithium ion battery is charged to 4.2V with a constant current of 0.5C, then charged to a current of 0.05C with a constant voltage of 4.2V, left to stand for 10min, then discharged to 3.0V with a current of 0.5C, the first discharge capacity is recorded as Q1D, the cycle is repeated 50 times in this way, and the discharge capacity at this time is recorded as Q50D, and then the discharge capacity/first retention rate discharge capacity after 50 charge-discharge cycles: η (%) = Q50D/Q1D × 100%;

in testing comparative examples 2 to 3 and examples 1 to 25, the test temperature was 25 ± 3 ℃, the lithium ion battery was charged to 8.4V at a constant current of 0.5C, then charged to a current of 0.05C at a constant voltage of 8.4V, left to stand for 10min, then discharged to 6.0V at a current of 0.5C, the first discharge capacity was recorded as Q1D, and thus the cycle was repeated 50 times, and the discharge capacity at this time was recorded as Q50D, and the discharge capacity/first discharge capacity retention ratio after 50 charge-discharge cycles was: η (%) = Q50D/Q1D × 100%.

The test method of the electronic resistivity of the bipolar current collector in the Z direction comprises the following steps:

taking a bipolar current collector sample of 10cm multiplied by 10cm, clamping the positive side and the negative side of the bipolar current collector by two metal clamping plates with fixed areas, wherein the area of each clamping plate is the same as that of the bipolar current collector, applying 0.1V voltage between the two clamping plates, measuring the current value between the two clamping plates, then calculating a resistance value R, and then calculating the electronic resistivity in the Z direction according to the following formula: ρ = RS/L. In the formula, R represents a resistance value, S represents an area of the bipolar current collector, and L represents a thickness of the bipolar current collector.

The test method of the water permeability of the bipolar current collector comprises the following steps:

and arranging a bipolar current collector with a certain thickness on a clamping mechanism, and pressing the edge of the bipolar current collector through rubber under high pressure. An environment with fixed temperature and humidity is built on one side A of the device, a water vapor mass spectrum detection probe is arranged on the other side B of the device, and gas exchange on the two sides can only pass through a bipolar current collector. In the testing process, the bipolar current collector is fixed, the cavity B is vacuumized, and water vapor in the cavity B is discharged. The mass spectrometer was then switched on and was continuously admittedThe water vapor permeating from the cavity A is converted into an electric signal to be output. The test is continued for 24 hours or more, the total amount m of water permeation in the period of time is obtained, and the water vapor permeability can be obtained by dividing the total amount m of permeation by the time, the water vapor partial pressure, the permeation area and the thickness of the bipolar current collector, wherein the unit g/(day m) is ² ·Pa·3mm)。

Hereinafter, embodiments of the present application will be described in more detail with reference to examples and comparative examples. Various tests and evaluations were carried out according to the following methods. In addition, "%" is based on weight unless otherwise specified.

Example 1

< preparation of negative electrode sheet >

Mixing Graphite (Graphite) serving as a negative active material, conductive carbon black (Super P) and Styrene Butadiene Rubber (SBR) according to a weight ratio of 96. And uniformly coating the slurry on one surface of a negative current collector copper foil with the thickness of 8 mu m, and drying at 110 ℃ to obtain the negative pole piece with the coating thickness of 130 mu m and the single-side coated negative active material. After the steps are completed, the single-side coating of the negative pole piece is completed. And then, repeating the steps on the other surface of the negative pole piece to obtain the negative pole piece with the negative active material coated on the two surfaces. After coating, the pole pieces were cut to 41mm × 61mm format for use.

< preparation of Positive electrode sheet >

The positive electrode active material lithium cobaltate (LiCoO) ₂ ) The conductive carbon black (Super P) and the polyvinylidene fluoride (PVDF) were mixed at a weight ratio of 97.5. And uniformly coating the slurry on one surface of a positive current collector aluminum foil with the thickness of 10 mu m, and drying at 90 ℃ to obtain a positive pole piece with the coating thickness of 110 mu m. And finishing the single-side coating of the positive pole piece after the steps are finished. Then, repeating the above steps on the other surface of the positive pole piece to obtain the positive pole with the positive active material coated on the two sidesAnd (4) pole pieces. After coating, the pole pieces were cut to a 38mm x 58mm gauge for use.

< preparation of electrolyte solution >

In a dry argon atmosphere, organic solvents of Ethylene Carbonate (EC), ethyl Methyl Carbonate (EMC) and diethyl carbonate (DEC) were first mixed at a mass ratio of EC: EMC: DEC = 50 ₆ ) Dissolving and mixing uniformly to obtain the electrolyte with the concentration of lithium salt of 1.15 mol/L.

< preparation of electrode Assembly >

And placing 15-micrometer PP diaphragms between the prepared positive pole piece and negative pole piece, and fixing the four corners after lamination to form a laminated electrode assembly, wherein the number of layers of the positive pole piece and the negative pole piece is respectively 13 and 14, two pole pieces at the outermost periphery of the laminated battery cell are single-sided pole pieces, and the rest are double-sided.

< preparation of Polymer conductive Current collector >

Spraying a PET material on a stainless steel substrate to obtain a PET layer, heating the PET layer to soften the PET layer, implanting conductive material MWCNT, spraying the PET material again to form a PET film, carrying out hot rolling on the obtained PET film, taking down the PET film from the surface of the stainless steel substrate by using a scraper, and rolling to obtain the high-molecular conductive current collector compounded by the PET and the MWCNT.

< preparation of lithium ion Battery >

Selecting a polymer conductive current collector compounded by PET and MWCNT as a bipolar current collector, wherein the thickness of the polymer conductive current collector is 100 μm, the electron resistivity in the Z direction is 0.06 omega-cm, and the water permeability is 5 multiplied by 10 ^-5 g/(day·m ² Pa.3 mm) and sealing layers are arranged at the peripheral edges of the bipolar current collector, wherein T/W is 0.025.

One of the outer packages (aluminum plastic film having a thickness of 150 μm) formed by punching a pit was placed in an assembly jig with the pit facing upward, and an electrode assembly (hereinafter referred to as electrode assembly a) was placed in the pit with the uppermost layer thereof being a negative electrode tab whose upper surface was free from a negative active material. And leading out the positive electrode tab of the electrode assembly A.

And then placing the bipolar current collector on the electrode assembly A to enable the bipolar current collector to be in contact with the negative pole piece of the electrode assembly A, and applying external force to compress the bipolar current collector.

And placing an electrode assembly (hereinafter referred to as an electrode assembly B) on the bipolar current collector, and enabling a positive pole piece of the electrode assembly to be in contact with the bipolar current collector, wherein the lower surface of the positive pole piece is not coated with a positive active material and is compressed by applying external force. Then, another outer package (aluminum plastic film with thickness of 150 μm) was placed face down over the electrode assembly B, the negative electrode tab of the electrode assembly B was drawn out, the injection port side was left, and then the other positions of the outer package were heat-sealed to obtain an assembled electrode assembly in which two independent cavities were formed on both sides of the bipolar current collector. Wherein the heat sealing temperature is 180 ℃ and the heat sealing pressure is 0.5MPa.

And independently injecting electrolyte into the two cavities of the assembled electrode assembly, and sealing after injecting the electrolyte.

In the charging and discharging process, only the positive electrode lug of the electrode assembly A and the negative electrode lug of the electrode assembly B are connected.

Example 2

The procedure was as in example 1, except that the bipolar current collector had a thickness of 15 μm as shown in Table 1.

Example 3

The procedure of example 1 was repeated, except that the bipolar current collector had a thickness of 5 μm as shown in Table 1.

Example 4

Except that a Cu-Al composite current collector was used as shown in Table 1, the bipolar current collector had an electron resistivity of 5.2X 10 in the Z direction ^-10 The procedure of example 2 was repeated except for the length of. Omega. Cm.

Example 5

The bipolar current collector had an electron resistivity of 9.3X 10 in the Z-direction, except that a stainless steel foil current collector was used as shown in Table 1 ^-10 The procedure of example 2 was repeated except for the length of. Omega. Cm.

Example 6

The procedure of example 2 was repeated, except that the bipolar current collector had an electron resistivity of 30. Omega. Cm in the Z direction as shown in Table 1.

Example 7

Except that the bipolar current collector has an electron resistivity of 1X 10 in the Z direction as shown in Table 1 ^-4 The procedure of example 2 was repeated except for the length of. Omega. Cm.

Example 8

Except that the water permeability of the bipolar current collector is 10 according to the table 1 ^-3 g/(day·m ² Pa.3 mm) was used in the same manner as in example 2.

Example 9

Except that the water permeability of the bipolar current collector is 10 according to the table 1 ^-7 g/(day·m ² Pa.3 mm) was used in the same manner as in example 2.

Example 10

The same procedures as in example 2 were repeated except that p-hydroxybenzaldehyde (PHBA) was used as a sealing material and the melting point of the sealing material was 115 ℃ as shown in Table 1.

Example 11

The same procedure as in example 2 was repeated, except that the melting point of the sealing material was set to 100 ℃ as shown in Table 1.

Example 12

The same procedure as in example 2 was repeated, except that the melting point of the sealing material was set to 200 ℃ as shown in Table 1.

Example 13

The same procedure as in example 2 was repeated, except that the thickness of the aluminum film was changed to 60 μm as shown in Table 1.

Example 14

The procedure of example 2 was repeated, except that the thickness of the aluminum-plastic film was changed to 500. Mu.m as shown in Table 1.

Example 15

The procedure was as in example 2 except that T/W was 0.005 as shown in Table 1.

Example 16

The procedure was as in example 2 except that T/W was 0.05 as shown in Table 1.

Example 17

The same procedure as in example 1 was repeated, except that the procedure for preparing the lithium ion battery was different from that of example 1.

< preparation of lithium ion Battery >

The procedure was as in example 1, except that the tab of the bipolar current collector was led out.

Example 18

< preparation of lithium ion Battery >

Selecting a polymer conductive current collector compounded by PET and MWCNT as a bipolar current collector, wherein the thickness of the polymer conductive current collector is 15 μm, the electron resistivity in the Z direction is 0.06 omega-cm, and the water permeability is 5 multiplied by 10 ^-5 g/(day·m ² Pa.3 mm) and sealing layers are arranged at the peripheral edges of the bipolar current collector, wherein T/W is 0.025, and the tabs of the bipolar current collector are led out.

One of the outer packages (aluminum plastic film having a thickness of 150 μm) formed by punching was placed in an assembly jig with the pit facing upward, and then an electrode assembly (hereinafter referred to as electrode assembly a) having a negative electrode tab on the uppermost layer thereof, the upper surface of which was free from a negative active material, was placed in the pit. And welding a plurality of positive pole tab leading-out sheets of the electrode assembly A into a positive pole tab in a transfer welding mode, and leading out the positive pole tab.

And placing an electrode assembly (hereinafter referred to as an electrode assembly B) on the bipolar current collector, enabling a positive pole piece of the electrode assembly to be in contact with the bipolar current collector, wherein the lower surface of the positive pole piece is not provided with a positive active material, and applying external force to compress the electrode assembly. Then, another outer package (aluminum plastic film with thickness of 150 μm) is covered on the electrode assembly B with the pit face facing downwards, a plurality of negative pole tab leading-out pieces of the electrode assembly B are welded into a negative pole tab in a transfer welding mode, the negative pole tab is led out, and the other positions of the outer package are heat-sealed after a liquid injection port side is left, so as to obtain an assembled electrode assembly, wherein two independent cavities are formed on two sides of the bipolar current collector. Wherein the heat sealing temperature is 180 ℃ and the heat sealing pressure is 0.5MPa.

And independently injecting electrolyte into the two cavities of the assembled electrode assembly, and sealing after injecting the electrolyte. In the charging and discharging process, only the positive electrode lug of the electrode component A and the negative electrode lug of the electrode component B are connected.

Example 19

< preparation of lithium ion Battery >

Selecting a polymer conductive current collector compounded by PET and MWCNT as a bipolar current collector, wherein the thickness of the polymer conductive current collector is 15 μm, the electron resistivity in the Z direction is 0.06 omega-cm, and the water permeability is 5 multiplied by 10 ^- ⁵ g/(day·m ² Pa.3 mm) and sealing layers are arranged at the peripheral edges of the bipolar current collector, wherein T/W is 0.025, and the tabs of the bipolar current collector are led out.

One sheet of the outer package (aluminum plastic film having a thickness of 200 μm) formed by punching was placed in an assembly jig with the pit facing upward, and then an electrode assembly (hereinafter referred to as electrode assembly a) was placed in the pit with the uppermost layer thereof being a negative electrode tab, the upper surface of which was free from a negative active material. And leading out the positive electrode tab of the electrode assembly A.

Then, a bipolar current collector (hereinafter referred to as bipolar current collector a) is placed on the electrode assembly a so as to be in contact with the negative electrode piece of the electrode assembly a, and is pressed by applying an external force.

And placing an electrode assembly (hereinafter referred to as an electrode assembly C) on the bipolar current collector A, enabling a positive pole piece of the electrode assembly to be in contact with the bipolar current collector A, wherein the lower surface of the positive pole piece is not provided with a positive active material, and applying external force to compress the electrode assembly.

And then placing a bipolar current collector (hereinafter referred to as bipolar current collector B) on the electrode assembly C, so that the bipolar current collector B is in contact with a negative pole piece of the electrode assembly C, and applying external force to compress the bipolar current collector B, wherein the upper surface of the negative pole piece is free from negative active materials.

And placing an electrode assembly (hereinafter referred to as the electrode assembly B) on the bipolar current collector B, enabling a positive pole piece of the electrode assembly to be in contact with the bipolar current collector B, wherein the lower surface of the positive pole piece is not provided with a positive active material, and applying external force to compress the electrode assembly. Then, another outer package (aluminum plastic film with thickness of 200 μm) is covered on the electrode assembly B with the pit face facing downward, the negative pole tab of the electrode assembly B is led out, and the other positions of the outer package are heat-sealed after the liquid injection port side is left, so as to obtain an assembled electrode assembly, wherein three independent cavities are formed on two sides of the bipolar current collector A, B. Wherein the heat sealing temperature is 180 ℃ and the heat sealing pressure is 0.5MPa.

And independently injecting electrolyte into the three cavities of the assembled electrode assembly, and sealing after injecting the electrolyte.

Example 20

The same procedure as in example 2 was repeated, except that the leading directions of the positive and negative electrode tabs were reversed.

Example 21

The procedure of example 2 was repeated, except that the bipolar current collector had an electron resistivity of 4. Omega. Cm in the Z direction as shown in Table 1.

Example 22

< preparation of negative electrode sheet >, < preparation of positive electrode sheet >, < preparation of electrolyte > and < preparation of electrode assembly > were the same as in example 1.

< preparation of Polymer conductive Current collector >

The same as example 2 was performed except that the conductive material was graphene.

< preparation of lithium ion Battery >

The procedure was repeated in example 2 except that a polymer conductive current collector obtained by compounding PET and graphene was used as a bipolar current collector, and the electron resistivity of the bipolar current collector in the Z direction shown in table 1 was 0.1 Ω · cm.

Example 23

The same procedure as in example 2 was repeated, except that the sealing material was polyester as shown in Table 1.

Example 24

< preparation of negative electrode sheet >

The same procedure as in example 1 was repeated except that the negative electrode sheet was cut into a size of 465mm × 92mm for use.

< preparation of Positive electrode sheet >

The same procedure as in example 1 was repeated, except that the positive electrode sheet was cut into a size of 480 mm. Times.90 mm.

< preparation of electrolytic solution >

Same as in example 1.

< preparation of electrode Assembly >

And (3) stacking the prepared positive pole piece, the prepared negative pole piece and a 15-micron PP diaphragm in the order of the positive pole piece, the diaphragm and the negative pole piece, so that the diaphragm is positioned between the positive pole piece and the negative pole piece to play a role in isolation, and winding to obtain the winding type electrode assembly.

< preparation of Polymer conductive Current collector >

Same as in example 1.

< preparation of lithium ion Battery >

The same as example 2 was repeated, except that the electrode assembly was the wound-type electrode assembly described above.

Example 25

Preparation of negative electrode sheet, preparation of positive electrode sheet, preparation of electrolyte, preparation of electrode assembly, and preparation of polymer conductive current collector were performed in the same manner as in example 24.

< preparation of lithium ion Battery >

The procedure of example 17 was repeated, except that the electrode assembly was the above-described wound-type electrode assembly.

The data and test results for examples 1-25 are shown in Table 1.

Comparative example 1

< preparation of lithium ion Battery >

One of the outer packages (aluminum plastic films having a thickness of 150 μm) formed by punching was placed in an assembly jig with the pit facing upward, and one electrode assembly (hereinafter referred to as electrode assembly a) was placed in the pit. Then, another outer package (aluminum plastic film with the thickness of 150 μm) is covered on the electrode assembly A with the pit surface facing downwards, the positive and negative electrode tabs of the electrode assembly A are led out, the liquid injection port side is left, and then other positions of the outer package are heat-sealed, so that the assembled electrode assembly is obtained. Wherein the heat sealing temperature is 180 ℃ and the heat sealing pressure is 0.5MPa.

The charging and discharging process only needs to connect the positive electrode lug and the negative electrode lug of the electrode component A.

Comparative example 2

< preparation of lithium ion Battery >

One of the outer packages (aluminum plastic film having a thickness of 150 μm) formed by punching a pit was placed in an assembly jig with the pit facing upward, and an electrode assembly (hereinafter referred to as electrode assembly a) was placed in the pit with the uppermost layer thereof being a negative electrode tab whose upper surface was free from a negative active material. The positive electrode tab of the electrode assembly a was led out.

An electrode assembly (hereinafter referred to as electrode assembly B) is placed on the electrode assembly A, a positive electrode sheet of the electrode assembly B is in contact with a negative electrode sheet of the electrode assembly A, a positive active material is not arranged on the lower surface of the positive electrode sheet, and external force is applied to compress the positive electrode sheet and the negative electrode sheet. Then, another external pack (aluminum plastic film having a thickness of 150 μm) was placed face down over the electrode assembly B, and the negative electrode tab of the electrode assembly B was taken out, leaving the liquid inlet side, and then the other portions of the external pack were heat-sealed to obtain an assembled electrode assembly. Wherein the heat sealing temperature is 180 ℃ and the heat sealing pressure is 0.5MPa.

And injecting electrolyte into the assembled electrode assembly, and sealing after injection.

Comparative example 3

< preparation of lithium ion Battery >

One of the outer packages (aluminum plastic films having a thickness of 150 μm) formed by punching was placed in an assembly jig with the pit facing upward, and then one electrode assembly (hereinafter referred to as electrode assembly a) was placed in the pit with the separator as the uppermost layer. And leading out the positive and negative electrode lugs of the electrode assembly A.

An electrode assembly (hereinafter referred to as electrode assembly B) is placed on the electrode assembly a, and a separator of the electrode assembly B is brought into contact with a separator side of the electrode assembly a, and a positive electrode sheet is placed over the separator, and is pressed by applying an external force. Then, another outer package (aluminum plastic film with thickness of 150 μm) was placed face down over the electrode assembly B, the positive and negative electrode tabs of the electrode assembly B were pulled out, and the other portions of the outer package were heat-sealed after leaving the injection port side, to obtain an assembled electrode assembly. Wherein the heat sealing temperature is 180 ℃ and the heat sealing pressure is 0.5MPa.

And injecting an electrolyte into the assembled electrode assembly, and sealing after injection.

The negative electrode tab of the electrode assembly a and the positive electrode tab of the electrode assembly B are welded together by laser welding, so that the electrode assemblies A, B are connected in series.

The data and test results for comparative examples 1-3 are shown in Table 1.

TABLE 1 preparation parameters and test results for examples and comparative examples

It can be seen from examples 1 to 25 and comparative examples 1 to 3 herein that the electrochemical devices (e.g., examples 1 to 25) having been connected in series within the bipolar current collector have a higher output voltage, and the discharge capacity/first discharge capacity of the electrochemical devices of examples 1 to 25 herein is significantly improved after 50 charge-discharge cycles.

Therefore, according to the electrochemical device provided by the application, the bipolar current collector is connected with the electrode assemblies in series, the periphery of the bipolar current collector is sealed with the outer package, the battery is divided into a plurality of independent sealing cavities, ions among the multiple electrode assemblies of the liquid series battery are isolated, the potential safety hazard of internal short circuit or electrolyte high-pressure decomposition is avoided, the safety performance of the electrochemical device is improved, and the effective electric energy output of the high-voltage battery is guaranteed. In addition, the electrode assemblies are connected in series inside through the winding or lamination structure and the design of the bipolar current collector, so that the structural design of series connection is realized without welding lugs among a plurality of electrode assemblies, the process is simplified, the production efficiency is improved, the problem of poor series connection of the electrochemical device caused by welding is avoided, the manufacturing reliability of the electrochemical device is greatly improved, and the output of electric energy is facilitated. In addition, the reduction of the number of the tabs effectively improves the energy density of the high-output voltage battery to a certain extent.

The above description is only exemplary of the present invention and should not be taken as limiting the invention, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

An electrochemical device comprises a bipolar current collector and electrode assemblies, wherein the electrode assemblies are positioned on two sides of the bipolar current collector, and the polarities of the electrode assemblies on the two sides, which are close to the outermost pole pieces of the bipolar current collector, are different.
The electrochemical device according to claim 1, wherein one side of the bipolar current collector is electrically connected to the outermost positive electrode tab of the electrode assembly adjacent thereto, and the other side of the bipolar current collector is electrically connected to the outermost negative electrode tab of the electrode assembly adjacent thereto.
The electrochemical device according to claim 1, wherein the bipolar current collector is connected to an outer package, and separate sealed cavities are formed on two sides of the bipolar current collector, and each sealed cavity contains one electrode assembly and electrolyte.
The electrochemical device of claim 3, the electrolyte comprising an organic solvent.
The electrochemical device of claim 1, wherein the bipolar current collector further comprises a sealing region in sealed connection with an overwrap, the sealing region comprising a sealing material having a melting point of 100 ℃ to 200 ℃.
The electrochemical device of claim 5, wherein the bipolar current collector comprises at least one of a Cu-Al composite current collector, a stainless steel foil current collector, or a polymeric conductive current collector;

the sealing material comprises at least one of polypropylene, polyester or p-hydroxybenzaldehyde.
The electrochemical device according to claim 1, wherein the bipolar current collector has an electron resistivity in the Z-direction of 1 x 10 ^-11 Omega cm to 30 omega cm.
The electrochemical device according to claim 1, wherein the bipolar current collector has a water permeability M ≦ 10 ^-3 g/(day·m ² ·Pa·3mm)。
The electrochemical device according to claim 1, wherein the bipolar current collector has a thickness of 2 μ ι η to 100 μ ι η.
The electrochemical device according to claim 3, wherein at the junction of the bipolar current collector and the outer package, a seal thickness T and a seal width W satisfy T/W ≦ 0.05, wherein T and W are in mm.
The electrochemical device of claim 10, having at least one of the following features:

a. the electrochemical device comprises 2 to 3 bipolar current collectors;

b. the melting point of the sealing material is 110-180 ℃;

c. the bipolar current collector has an electron resistivity of 1 × 10 in the Z direction ^-5 Omega cm to 5 omega cm;

d. the water permeability M of the bipolar current collector is less than or equal to 10 ^-4 g/(day·m ² ·Pa·3mm)；

e. The bipolar current collector is 5-50 μm thick;

f. the seal thickness T and the seal width W meet the condition that T/W is more than or equal to 0.02 and less than or equal to 0.04.
The electrochemical device of claim 11, having at least one of the following features:

1) The melting point of the sealing material is from 120 ℃ to 160 ℃;

2) The bipolar current collector has an electron resistivity in the Z direction of 0.01 Ω · cm to 0.10 Ω · cm;

3) The bipolar current collector has a thickness of 5 to 20 μm.
The electrochemical device of claim 1, wherein the structure of the electrode assembly comprises at least one of a wound structure or a laminated structure.
An electronic device comprising the electrochemical device of any one of claims 1-13.