CN114631221A

CN114631221A - Electrochemical device and electronic device comprising same

Info

Publication number: CN114631221A
Application number: CN202080015147.1A
Authority: CN
Inventors: 严坤; 张益博; 丁宇; 刘道林
Original assignee: Ningde Amperex Technology Ltd
Current assignee: Ningde Amperex Technology Ltd
Priority date: 2020-09-27
Filing date: 2020-09-27
Publication date: 2022-06-14
Also published as: WO2022061810A1

Abstract

The present application relates to an electrochemical device and an electronic device including the same. Specifically, the present application provides an electrochemical device comprising an outer package, a separator and electrode assemblies disposed on both sides of the separator, respectively, the separator and the electrode assemblies being disposed in the outer package, the separator extending from one of the seal edges of the outer package, the portion of the separator extending out of the outer package being provided with a heat sink. Through the design of the heat conduction mode of the partition plate, the overheating condition caused by heat accumulation in the use process of the electrochemical device is effectively avoided.

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, many scenarios need to use voltages exceeding 5V, such as application scenarios of Electric Vehicles (EV), voltage transformers (PT), Energy Storage Systems (ESS), and the like.

In order to increase the output voltage of the lithium ion battery, in the prior art, a plurality of lithium ion batteries are generally connected in series under the condition of being stacked in the thickness direction, but due to the close contact of the adjacent lithium ion batteries in the thickness direction, the heat dissipation surface area is reduced, the temperature of the lithium ion battery is easily overhigh, and the lithium ion battery is overheated and even causes safety accidents.

Disclosure of Invention

An electrochemical device and an electronic device including the same are provided to prevent overheating of the electrochemical device during use.

The present application provides in a first aspect an electrochemical device comprising an outer package, a separator and electrode assemblies disposed on both sides of the separator, wherein the separator is disposed in the outer package, the separator extends from one of the outer package seal edges, and the separator extends from the outer package seal edge to a length of 3mm to 30 mm.

In some embodiments of the present application, the divider extends from the bottom or side seal edge of the overwrap seal edge.

In some embodiments of the present application, the portion of the baffle plate extending out of the outer package is provided with a heat sink comprising a finned heat sink or a finned heat sink.

In some embodiments of the present application, the separator is connected to the exterior package, and sealed cavities are formed at both sides of the separator, respectively, and each sealed cavity encloses an electrode assembly and an electrolyte.

In some embodiments of the present application, the electrode assembly is provided with tabs of different polarities extending out of the overwrap, adjacent electrode assemblies being connected in series by the tabs.

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

In some embodiments of the present application, each electrode assembly has two tabs of opposite polarities protruding out of the external pack, and adjacent two electrode assemblies are connected in series by the tabs.

In some embodiments of the present application, the separator plate is a bipolar separator plate comprising at least one of a Cu-Al composite current collector, a stainless steel foil current collector, or a polymeric conductive current collector.

In some embodiments of the present application, one side of the bipolar separator is provided with an electrode active material layer, the outermost layer of the electrode assembly adjacent to the electrode active material layer is provided with an electrode active material layer with opposite polarity, a separator is arranged between the side of the bipolar separator provided with the electrode active material layer and the adjacent electrode assembly, the other side of the bipolar separator is electrically insulated from the adjacent electrode assembly, and the bipolar separator leads out a tab connected with tabs of the electrode assemblies on both sides in series.

In some embodiments of the present application, one side of the bipolar separator is provided with an electrode active material layer, 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 disposed between the side of the bipolar separator provided with the electrode active material layer and the adjacent electrode assembly, and the other side of the bipolar separator is electrically connected to the adjacent electrode assembly.

In some embodiments of the present application, both sides of the bipolar separator are respectively provided with electrode active material layers of different polarities, the outermost layer of the electrode assembly adjacent to each electrode active material layer is provided with electrode active material layers of opposite polarities, and a separator is disposed between the electrode active material layers of the bipolar separator and the outermost electrode active material layers of the electrode assembly.

In some embodiments of the present application, the partition is hermetically connected to the overwrap, and the portion of the partition sealed to the overwrap comprises an encapsulating material comprising at least one of polypropylene, anhydride-modified polypropylene, polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid copolymer, ethylene-vinyl alcohol copolymer, polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, polyamide, polyester, amorphous α -olefin copolymer, and derivatives thereof. In some embodiments of the present application, the separator has a thickness of 6 μm to 100 μm.

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

a. the electrochemical device comprises 2 to 3 separators;

b. the thickness of the separator is 10 to 40 μm;

c. the length of the partition plate extending out of the outer package sealing edge is 5mm to 20 mm.

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 the introduction of baffle and the sealing connection of baffle and extranal packing, separate lithium ion battery for a plurality of independent seal chamber, realize that the ion between different seal chamber is isolated, avoid taking place the potential safety hazard of interior short circuit or electrolyte high pressure decomposition to improve electrochemical device's security performance, guaranteed the effectual electric energy output of electrochemical device. Meanwhile, the partition plate extends out of one side of the seal edge of the outer package, and the part of the partition plate extending out of the outer package is provided with the heat dissipation device, so that part of heat in the electrochemical device is conducted out through contact heat transfer, and the overheating condition caused by heat accumulation of the electrochemical device in the use process can be avoided.

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 top view of an electrochemical device according to one embodiment of the present application;

FIG. 2 is a schematic view of an electrochemical device according to an embodiment of the present application;

FIG. 3 is an exploded view of the electrochemical device of FIG. 2;

FIG. 4 is a schematic view of an electrochemical device according to an embodiment of the present application;

FIG. 5 is a partial sectional view of the internal structure of the electrochemical device of FIG. 4;

FIG. 6 is a partial sectional view of an electrochemical device according to an embodiment of the present application;

fig. 7 is a partial sectional 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 capable of using 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.

A first aspect of the present application provides an electrochemical device comprising an exterior package, a separator and an electrode assembly disposed on both sides of the separator, respectively, the separator and the electrode assembly being located in the exterior package, the separator protruding from one of seal edges of the exterior package;

the length of the partition plate extending out of the seal edge of the outer package is 3mm to 30mm, preferably 5mm to 20 mm; when the length of the partition plate extending out of the seal edge of the outer package is less than 3mm, the extending part of the partition plate is too short, so that the heat dissipation effect is poor, or the partition plate is difficult to be sufficiently and effectively connected with a heat dissipation device, and the effective heat dissipation effect cannot be achieved; when the length of the separator extending out of the seal edge of the outer package is greater than 30mm, the energy density of the electrochemical device can be reduced due to the excessively long extension part of the separator.

Generally, the "outer package sealing edge" refers to a sealing area formed around the outer package after the outer package is sealed and packaged, wherein the sealing edge extending out of one side of the tab is a top sealing edge, one side opposite to the top sealing edge is a bottom sealing edge, and two opposite sealing edges in the width direction of the outer package perpendicular to the top sealing edge are side sealing edges.

In this application, the spacer may extend from the bottom or side seal edge of the outer package seal edge. The overwrap seal edges include two side seals, and in one embodiment, the septum of the present application may extend from one of the two side seals. Referring to fig. 1, the "outer package seal edge" includes a bottom seal edge 52 and two

side seal edges

51, 53, excluding a top seal edge 54.

In some embodiments of the present application, the electrochemical device includes separators, and the specific number of the separators is not limited, and those skilled in the art can select the separators according to actual needs as long as the purpose of the present application can be achieved, for example, 2 to 3 separators are included.

In some embodiments of the present application, the portion of the partition plate extending out of the outer package is provided with a heat sink, and in the present application, the kind of the heat sink is not particularly limited as long as the object of the present application can be achieved, and for example, the heat sink may include one of a fin type heat sink, a finned type heat sink, and the like.

In some embodiments of the present application, the separator is hermetically connected to the outer package, and two sealing cavities are formed on two sides of the separator, and each sealing cavity is packaged with an electrode assembly and an electrolyte, so that ion insulation is achieved between the sealing cavities, thereby avoiding the problem of short circuit inside the electrochemical device and the problem of electrolyte decomposition under high voltage, and thus improving the safety performance of the electrochemical device and ensuring effective power output of the electrochemical device. The partition plate extends out of one side of the seal edge of the outer package, and a heat dissipation device is arranged on the part of the partition plate extending out of the outer package, so that heat in the electrochemical device can be timely conducted out.

In some embodiments of the present application, the electrode assembly is provided with tabs of different polarities extending out of the overwrap, adjacent electrode assemblies being connected in series by the tabs. When all the lugs arranged on the electrode assembly are led out of the outer package for welding, the welding effect of the lugs can be monitored at any time, the fracture risk of the lugs is reduced, and the problem of increased internal resistance of an electrochemical device due to poor welding effect of the lugs is avoided; the adjacent electrode assemblies are connected in series, so that the output voltage of the electrochemical device can be effectively increased.

Fig. 2 shows an embodiment of the present application, and fig. 3 is an exploded view of the electrochemical device of fig. 2. referring to fig. 2 and 3, the electrode assembly 31 and the electrode assembly 32 are separated by a separator 40, the separator 40 extends from the side sealing edge 53, and the portion of the separator extending out of the exterior pack 10 is connected to an external heat sink, thereby conducting internal heat away. The separator 40 is hermetically connected to the exterior package 10, and separate sealed cavities, each containing one electrode assembly and electrolyte, are formed at both sides of the separator 40, and are ion-insulated from each other. The negative electrode tab 22 of the electrode assembly 31 and the positive electrode tab 23 of the electrode assembly 32 are extended out of the exterior package 10 and then connected in series to form a tab 25, and the positive electrode tab 21 of the electrode assembly 31 and the negative electrode tab 24 of the electrode assembly 32 serve as positive and negative terminals for connection during charging and discharging.

The polymer film is not particularly limited as long as the present application can be achieved, and for example, 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, at least one of polyethylene naphthalate, polypropylene carbonate, poly (vinylidene fluoride-hexafluoropropylene), poly (vinylidene fluoride-co-chlorotrifluoroethylene), silicone resin, vinylon, polypropylene (PP), Polyethylene (PE), polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, polyphenylene oxide, polysulfone, amorphous α -olefin copolymer, and derivatives thereof.

The metal foil is not particularly limited as long as the object of the present application can be achieved, and for example, may include at least one of Ni, Ti, Cu, Ag, Au, Pt, Fe, Co, Cr, W, Mo, Al, Mg, K, Na, Ca, Sr, Ba, Si, Ge, Sb, Pb, In, Zn, stainless steel (SUS), and a composition or alloy thereof. Preferably, a metal foil with good oxidation and reduction resistance in a lithium ion battery environment can be selected. More preferably, a metal or alloy-based metal foil that conducts heat well may be selected.

The carbon material is not particularly limited as long as the object of the present application can be achieved, and for example, may include at least one of a single-walled carbon nanotube, a multi-walled carbon nanotube (MWCNT), a carbon felt, a carbon film, carbon black, acetylene black, fullerene, a conductive graphite film, or a graphene film.

In some embodiments of the present application, the material of the separator is preferably a polymer film, and since the polymer film has a low density, the weight of the inactive material may be reduced, thereby increasing the mass energy density of the electrode assembly. In addition, the material of the partition board is made of high polymer material, so that the probability of generating fragments is lower under the condition of mechanical abuse (through nails, impact, extrusion and the like), and the wrapping effect on the damaged surface of the machine is better, so that the safety boundary under the condition of mechanical abuse can be improved, and the safety test passing rate is improved.

In some embodiments of the present application, the material of the separator is preferably a metal foil, which has high isolation reliability, and the metal foil has toughness and compactness superior to those of a polymer material, and can also be made thinner.

In some embodiments of the present application, the material of the separator is preferably a carbon material, which has excellent safety performance, especially good thermal conductivity and excellent high-temperature reliability.

In some embodiments of the present application, the material of the separator may further include a composite material formed by compounding at least two of a polymer film, a metal foil, and a carbon material. The type of the composite material is not particularly limited, and any material known to those skilled in the art may be used as long as the object of the present application can be achieved, and for example, a Ni metal surface layer composite PP film, an Ag metal surface layer composite PET film, or the like may be included.

In some embodiments of the present application, each electrode assembly has two tabs of opposite polarities protruding out of the external pack, and the adjacent two electrode assemblies are connected in series by the tabs.

The polymer current collector comprises a composite material of a polymer material and a conductive material, the polymer current collector is not particularly limited in the application, as long as the purpose of the application can be achieved, for example, the polymer current collector comprises a polymer matrix and a conductive agent, 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 0-30 degrees with the thickness direction of the polymer matrix. The other polymer conductive current collector comprises conductive layers respectively arranged on two surfaces of a polymer substrate, and the two conductive layers are electrically connected. 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. Another typical example of a polymeric conductive current collector is the presence of layers of the same or different metallic materials on both surfaces of the polymeric material.

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

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, one side of the bipolar separator is provided with an electrode active material layer, the outermost layer of the electrode assembly adjacent to the electrode active material layer is provided with an electrode active material layer with opposite polarity, a separator is arranged between the side of the bipolar separator provided with the electrode active material layer and the adjacent electrode assembly, the other side of the bipolar separator is electrically insulated from the adjacent electrode assembly, and the bipolar separator leads out a tab connected with tabs of the electrode assemblies on both sides in series. In this embodiment, the first side of the bipolar separator and the outermost electrode tab of the adjacent electrode assembly form an electrochemical unit, which participates in the charge and discharge processes of the electrochemical device, thereby increasing the energy density of the electrochemical device. The bipolar separator is provided with tabs, which are connected with tabs connected with the electrode assemblies on two sides in series, so as to provide high output voltage.

Fig. 4 is a schematic view of an electrochemical device according to another embodiment of the present application, and fig. 5 is a partial sectional view of the internal structure of the electrochemical device of fig. 4, referring to fig. 4 and 5, the separator 40 of the present embodiment is a bipolar separator, the a side of the bipolar separator is provided with a positive electrode active material layer 71, the outermost of the electrode assembly 31 adjacent to the positive electrode active material layer 71 is provided with a negative electrode active material layer 72, and a separator 80 is provided between the positive electrode active material layer 71 on the a side of the bipolar separator and the outermost negative electrode active material layer 72 of the adjacent electrode assembly 31; the B side of the bipolar separator has no electrode active material layer, and the outermost layer of the electrode assembly 32 adjacent thereto is provided with a separator 80, thereby electrically insulating the B side of the bipolar separator from the adjacent electrode assembly 32; the bipolar separator is led out with a positive pole tab 27, the negative pole tab 22 of the electrode assembly 31 and the positive pole tab 23 of the electrode assembly 32 are connected in series to form a tab 25 outside the outer package 10 (as shown in fig. 2), the positive pole tab 27 is connected with the tab 25 to provide high output voltage, and the positive pole tab 21 of the electrode assembly 31 and the negative pole tab 24 of the electrode assembly 32 are used as positive and negative terminals for connection during charging and discharging. It will be understood by those skilled in the art that the positive electrode active material layer on the a-side of the bipolar separator may also be a negative electrode active material layer, in which case the outermost layer of the electrode assembly adjacent to the a-side includes a positive electrode active material layer.

In some embodiments of the present application, an electrode active material layer is disposed on one side of the bipolar separator, an electrode active material layer having an opposite polarity is disposed on an outermost layer of the electrode assembly adjacent to the electrode active material layer, a separator is disposed between one side of the bipolar separator, on which the electrode active material layer is disposed, and the adjacent electrode assembly, and an electrical connection is made between the other side of the bipolar separator and the adjacent electrode assembly.

In the present application, the above-mentioned "electrically connected" means that the side of the bipolar separator plate not provided with the electrode active material is electrically connected through physical contact with the outermost current collector of the adjacent electrode assembly, that is, the surface of the electrode sheet electrically connected with the bipolar separator plate is free of the electrode active material.

In some embodiments of the present application, the bipolar separator may not have tabs, in which case, the electrode assemblies on both sides of the bipolar separator are directly connected in series through the bipolar separator, the electrochemical device may only have two tabs with opposite polarities, and when more than two electrode assemblies are contained in the electrochemical device, all the electrode assemblies are connected in series through the bipolar separator between the two tabs with opposite polarities.

In some embodiments of the present application, the bipolar separator may also lead out a tab, which is connected to a tab of the same polarity on one side of the electrode assembly on which the electrode active material is disposed of the bipolar separator in parallel, and then connected to a tab of the opposite polarity on the other side of the electrode assembly in series, in which case, the two electrode assemblies may be connected in series through the inside of the bipolar separator and in series through the outside of the tab. In addition, the polar lugs of the bipolar separator can be not connected with the polar lugs of the electrode assembly and are only used for monitoring the voltage of the electrochemical device, the problem electrode assembly can be checked in time, failure reasons can be found, and the manufacturing yield and the production efficiency of the electrochemical device are improved.

Fig. 6 is a partial schematic view showing a cross-sectional view of the internal structure of an electrochemical device according to an embodiment of the present invention, in which, as shown in fig. 6, a separator 40 according to the present embodiment is a bipolar separator, an a side of the bipolar separator is provided with an anode active material layer 72, an outermost side of an electrode assembly 31 adjacent to the anode active material layer 72 is provided with a cathode active material layer 71, and a separator 80 is provided between the anode active material layer 72 on the a side of the bipolar separator and the cathode active material layer 71 of the outermost side of the adjacent electrode assembly 31; the side B of the bipolar separator has no electrode active material layer, the outermost layer of the electrode assembly 32 adjacent to the side B of the bipolar separator is a positive electrode collector 61, and the positive electrode collector 61 is electrically connected to the side B of the bipolar separator 0. The electrode assembly 31 and the electrode assembly 32 can be directly connected in series through a bipolar separator, and only the positive electrode tab of the electrode assembly 31 and the negative electrode tab of the electrode assembly 32 are led out to serve as positive and negative terminals for connection during charging and discharging. The bipolar separator may also be provided with a negative electrode tab connected in parallel with the negative electrode tab of the electrode assembly 31 and then connected in series with the positive electrode tab of the electrode assembly 32, wherein the two

electrode assemblies

31, 32 are connected in series both through the inside of the bipolar separator and through the outside of the tabs. Alternatively, the tabs on the bipolar separator may not be connected to the tabs of the electrode assembly and are used only to monitor the voltage of the electrochemical device.

It will be understood by those skilled in the art that the negative active material layer on the a side of the bipolar separator may also be a positive active material layer, in which case, the outermost layer of the electrode assembly adjacent to the a side is provided with a negative active material layer, the outermost layer of the electrode assembly adjacent to the B side of the bipolar separator is a negative current collector 62, and the adjacent electrode assemblies may be directly connected in series through the bipolar separator.

In some embodiments of the present application, both sides of the bipolar separator are respectively provided with electrode active material layers of different polarities, the outermost layer of the electrode assembly adjacent to each electrode active material layer is provided with electrode active material layers of opposite polarities, and a separator is disposed between the electrode active material layers of the bipolar separator and the outermost electrode active material layers of the electrode assembly. Two sides of the bipolar separator are respectively provided with electrode active material layers with different polarities, and the two sides of the bipolar separator and the outermost electrode pole piece of the adjacent electrode assembly form an electrochemical unit, so that the energy density of the battery is further improved.

The electrode assemblies on the two sides of the bipolar separator can be directly connected in series through the bipolar separator, and can also be connected in series through the bipolar separator and two lugs with opposite polarities.

Fig. 7 is a partial sectional view showing the internal structure of an electrochemical device according to an embodiment of the present invention, and as shown in fig. 7, the separator 40 according to the present embodiment is a bipolar separator, the a side of the bipolar separator is provided with an anode active material layer 72, the outermost layer of the electrode assembly 31 adjacent to the a side of the bipolar separator is a cathode active material layer 71, the B side of the bipolar separator is provided with a cathode active material layer 71, the outermost layer of the electrode assembly 32 adjacent to the B side of the bipolar separator is an anode active material layer 72, a separator 80 is respectively provided between the electrode active material layers of the a and B sides of the bipolar separator and the outermost layer of the electrode assembly adjacent thereto, and the electrode assembly 31 and the electrode assembly 32 are directly connected in series through the bipolar separator.

In some embodiments of the present application, two sides of the bipolar separator are respectively provided with electrode active material layers with different polarities, and a tab is disposed on the bipolar separator, and the tab may be used for monitoring the voltage of the electrochemical device or insulating and coating the tab. The electrode lug can also be connected with the series electrode lugs of the electrode components at two sides of the bipolar separator.

In some embodiments of the present application, the partition is hermetically connected to the overwrap, and the portion of the partition sealed to the overwrap comprises an encapsulating material comprising at least one of polypropylene, anhydride-modified polypropylene, polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid copolymer, ethylene-vinyl alcohol copolymer, polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, polyamide, polyester, amorphous α -olefin copolymer, and derivatives thereof. The packaging material can be effectively connected with the outer package in a sealing manner, so that the safety of the electrochemical device is improved.

In the present application, the size of the seal edge formed after the partition and the outer package are sealed is not particularly limited as long as the object of the present application can be achieved. For example, the thickness T (unit: mm) and the width W (unit: mm) of the seal edge satisfy 0.01 ≦ T/W ≦ 0.05. The ratio of T/W is in the range, so that the sealing of the battery can be ensured to be good, and the service life of the battery can be prolonged. When the T/W is too small, the sealing thickness is possibly insufficient, the sealing effect is poor, and the environmental stability of the battery is reduced, for example, water vapor in the environment is easy to permeate into the battery, so that the moisture content in the battery is increased, the electrolyte is decomposed, and the service life of the battery is reduced; too large ratio of T/W may result in too small seal width W, which also results in poor sealing effect, resulting in reduced environmental stability of the battery, for example, moisture in the environment is easy to permeate into the battery, resulting in increased moisture content in the battery, decomposition of electrolyte, and the like, and reducing the service life of the battery. In the present application, the seal thickness and the seal width are not particularly limited as long as the object of the present application can be achieved, and for example, the width W of the seal edge is preferably 1mm to 7 mm.

In the packaging process of the present application, the polymer material in the outer package and the polymer material in the sealing material are hot-press sealed together. Therefore, the seal thickness includes the thickness after the polymer material in the seal material is fused with the polymer material in the inner layer of the outer package. The seal width refers to the width of a seal area formed by combining a high polymer material in the seal material and a high polymer material in an inner layer of the outer package after hot-press sealing. In some embodiments of the present application, the thickness of the separator is 6 μm to 100 μm, preferably 10 μm to 40 μm, and more preferably 20 μm to 30 μm. When the thickness of the separator is less than 6 μm, the mechanical strength of the separator may be insufficient, easily causing damage to affect the performance or even safety of the electrochemical device; when the thickness thereof is more than 100 μm, the mass of the introduced inactive material increases, decreasing the energy density of the electrochemical device.

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

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 may be respectively led out from each layer of positive electrode plate and negative electrode plate, and finally, the electrode assembly of the laminated structure includes a plurality of sets of positive tabs and negative tabs, and then the metal sheets are led out through transfer welding tabs.

In the present application, the "tab" generally refers to a metal conductor extracted from the positive electrode tab or the negative electrode tab for connecting other parts of the electrochemical device in series or in parallel. The positive pole tab is led out from the positive pole piece, and the negative pole tab is led out from the negative pole piece.

In the present application, the material of the tab is not particularly limited as long as the object of the present application can be achieved. For example, the positive electrode tab material includes at least one of aluminum (Al) or an aluminum alloy, and the negative electrode tab material includes at least one of nickel (Ni), copper (Cu), or copper-plated nickel (Ni — Cu).

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 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 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. For example, at least one of a Polyolefin (PO) separator mainly composed of Polyethylene (PE) and polypropylene (PP), a polyester film (for example, a polyethylene terephthalate (PET) film), a cellulose film, a polyimide film (PI), a polyamide film (PA), a spandex or aramid film, a woven film, a nonwoven film (nonwoven fabric), a microporous film, a composite film, a separator paper, a roll film, a spun film, and the like.

For example, the separator may include a substrate layer and a surface treatment layer. The substrate layer may be a non-woven fabric, a film or a composite film having a porous structure, and the material of the substrate layer may include at least one of 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 the group consisting of 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, and polyhexafluoropropylene. 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 typically includes a positive electrode current collector and a positive electrode active material. In the present application, the positive electrode current collector is not particularly limited, and may be any positive electrode current collector known in the art, for example, a copper foil, an aluminum alloy foil, a composite current collector, and the like. The positive electrode active material is not particularly limited and may be any of positive electrode active materials of the prior art, for example, the positive electrode active material includes at least one of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminate, lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, lithium iron manganese phosphate, or the like. In the present application, the thickness of the positive electrode current collector and the positive electrode active material is not particularly limited as long as the object of the present application can be achieved. For example, the thickness of the positive electrode current collector is 8 to 12 μm, and the thickness of the positive electrode active material is 30 to 120 μm.

Optionally, the positive electrode sheet may further include a conductive layer between the positive electrode current collector and the positive electrode active material layer. The composition of the conductive layer is not particularly limited, and may be a conductive layer commonly used in the art. 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. In the present application, the negative electrode current collector is not particularly limited, and any negative electrode current collector known in the art, such as a copper foil, an aluminum alloy foil, a composite current collector, and the like, may be used. The anode active material is not particularly limited, and any anode active material known in the art may be used. For example, at least one of artificial graphite, natural graphite, mesocarbon microbeads, silicon carbon, silicon oxy-compound, soft carbon, hard carbon, lithium titanate, niobium titanate, or the like may be included. In the present application, the thickness of the anode current collector and the anode active material is not particularly limited as long as the object of the present application can be achieved. For example, the thickness of the negative electrode current collector is 6 to 10 μm, and the thickness of the negative electrode active material is 30 to 120 μm.

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

The above-mentioned conductive agent is not particularly limited 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. The adhesive is not particularly limited, and any adhesive known in the art may be used as long as the object of the present application can be 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 as long as the object of the present application can be achieved. 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 as long as the object of the present application can be achieved. For example, the lithium salt may include LiPF₆、LiBF ₄、LiAsF ₆、LiClO ₄、LiB(C ₆H ₅) ₄、LiCH ₃SO ₃、LiCF ₃SO ₃、LiN(SO ₂CF ₃) ₂、LiC(SO ₂CF ₃) ₃Or LiPO₂F ₂And the like. For example, LiPF is used as lithium salt₆。

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

For example, the carbonate compound may include 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, 2-trifluoroethylene carbonate, 1,2, 2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1, 2-difluoro-1-methylethylene carbonate, 1, 2-trifluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1, 2-trifluoro-2-methylethylene carbonate, At least one of trifluoromethyl ethylene carbonate and the like.

In the present application, the outer package is not particularly limited as long as the object of the present application can be achieved.

For example, the outer package may include an inner layer and an outer layer, the inner layer being hermetically connected to the bipolar current collector, and thus the material of the inner layer may include a polymer material, thereby achieving a good sealing effect; meanwhile, the combination of the inner layer and the outer layer can effectively protect the internal structure of the electrochemical device. In the present application, the material of the inner layer is not particularly limited as long as the object of the present application can be achieved, and for example, the material of the inner layer includes at least one of polypropylene, polyester, parahydroxybenzaldehyde, polyamide, polyphenylene ether, polyurethane, and the like. In the present application, the material of the outer layer is not particularly limited as long as the object of the present application can be achieved, and for example, the material of the outer layer includes at least one of an aluminum foil, an aluminum oxide layer, a silicon nitride layer, and the like.

For example, the overwrap may be an aluminum foil film comprising a nylon layer, an aluminum foil layer, and a PP layer.

In the present application, the thickness of the outer package is not particularly limited as long as the object of the present application can be achieved. For example, the thickness of the outer package may be 60 μm to 500 μm, preferably 60 μm to 300 μm, and more preferably 60 μm to 200 μm. The outer package of the above thickness can effectively protect the internal structure of the electrochemical device.

The present application does not specifically limit the sealing connection manner between the separator and the outer package, as long as the object of the present application can be achieved. For example, the sealing means includes one of hot pressing, glue sealing, and welding. In the present application, the hot pressing conditions are not particularly limited as long as the object of the present application can be achieved, and for example, the hot pressing temperature is 150 ℃ to 220 ℃ and the hot pressing pressure is 0.1MPa to 0.6MPa for the polypropylene inner layer material.

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 devices described herein include electronic devices that are common in the art, such as notebook computers, pen-input computers, mobile computers, electronic book players, cellular phones, portable facsimile machines, portable copiers, portable printers, headphones, video recorders, liquid crystal televisions, portable cleaners, portable CD players, mini-discs, transceivers, electronic organizers, calculators, memory cards, portable recorders, radios, backup power sources, motors, automobiles, motorcycles, mopeds, bicycles, lighting fixtures, toys, game machines, clocks, electric tools, flashlights, cameras, household large-sized batteries, lithium ion capacitors, 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:

0.1C discharge energy density:

the electrochemical device is kept still for 30 minutes at normal temperature, the constant current charging is carried out at the charging rate of 0.05C until the voltage is 4.4V (rated voltage), then the electrochemical device is discharged to 3.0V at the rate of 0.05C, and the charging/discharging steps are repeated for 3 cycles to complete the formation of the electrochemical device to be tested. After completion of formation of the electrochemical device, the electrochemical device was subjected to constant current charging at a charge rate of 0.1C to a voltage of 4.4V, followed by discharging the electrochemical device at a discharge rate of 0.1C to 3.0V, recording the discharge capacity thereof, followed by calculation of the energy density thereof at 0.1C discharge:

energy density (Wh/L) discharge capacity (Wh)/electrochemical device volume size (L)

2C discharge temperature rise:

placing the fully charged chemical device in a terminal heat dissipation device, wherein one side of the fully charged chemical device is in contact with the terminal heat dissipation device, and the other side of the fully charged chemical device is exposed; sticking a temperature probe on the surface of the exposed side to monitor the temperature of the electrochemical device; adhering the partition part extending out of the side edge of the electrochemical device to the heat dissipation device by using gummed paper, and if no partition plate extends out, not processing; the discharge was carried out at 2C for 15 minutes and the maximum surface temperature was monitored.

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. Unless otherwise specified, "%" and "parts" are based on mass.

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 96:1.5:2.5, adding deionized water serving as a solvent, blending to obtain slurry with the solid content of 70%, and uniformly stirring. 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. And after the steps are completed, finishing the single-side coating of the negative pole piece. 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) Mixing conductive carbon black (Super P) and polyvinylidene fluoride (PVDF) according to the weight ratio of 97.5:1.0:1.5, adding N-methylpyrrolidone (NMP) as a solvent, preparing into slurry with the solid content of 75%, and uniformly stirring. And uniformly coating the slurry on one surface of an aluminum foil of the positive current collector 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. And then, repeating the steps on the other surface of the positive pole piece to obtain the positive pole piece with the positive active material coated on the two surfaces. Coating compositionAfter the cloth is finished, the pole pieces are cut into the specification of 38mm multiplied by 58mm for standby.

< 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 in a mass ratio of EC: EMC: DEC: 30:50:20, and then lithium salt lithium hexafluorophosphate (LiPF) was added to the organic solvent₆) 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 a 15-micrometer PP diaphragm between the prepared positive pole piece and the negative pole piece, and fixing the four corners after laminating 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.

< preparation of separator >

Uniformly dispersing polystyrene serving as a packaging material into N-methylpyrrolidone (NMP) serving as a dispersing agent to prepare a suspension of the packaging material; coating a packaging material on a position where a partition PP film with the thickness of 30 mu m and an outer package are packaged by using a glue spreader; and drying the dispersing agent NMP in the packaging material suspension at 130 ℃ to finish the preparation of the separator. Wherein the melting point of the partition board is 150 ℃, and the melting point of the packaging material is 240 ℃.

< preparation of lithium ion Battery >

One of the outer packages (aluminum plastic films having a thickness of 90 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. One positive electrode tab and one negative electrode tab are drawn from the electrode assembly a.

And then, placing the separator on the electrode assembly A to be in contact with the electrode assembly A, and applying external force to compress the separator, wherein the separator is aligned with the edges of the top sealing edge, the bottom sealing edge and the first side sealing edge of the outer package and extends out of the second side sealing edge of the outer package, and the length of the extending part of the separator is 5 mm.

An electrode assembly (hereinafter, electrode assembly B) was placed on the separator, brought into contact with the separator, and pressed by applying an external force. A positive electrode tab and a negative electrode tab are drawn from the electrode assembly B.

And then welding the negative electrode tab of the electrode assembly A and the positive electrode tab of the electrode assembly B together by laser welding, connecting the negative electrode tab and the positive electrode tab in series, and extending the tabs after the series connection out of the outer package.

Then, the positive electrode tab of the electrode assembly a and the negative electrode tab of the electrode assembly B were protruded out of the exterior package.

Then, another outer package (aluminum plastic film having a thickness of 90 μm) was placed face down over the electrode assembly B, and the other portions of the outer package were heat-sealed after leaving the injection port side to obtain an assembled electrode in which two independent cavities were formed on both sides of the separator. Wherein the heat sealing temperature is 180 ℃ and the heat sealing pressure is 0.5 MPa.

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 2

The procedure of example 1 was repeated, except that the separator material was a Ti metal foil as shown in Table 1.

Example 3

The same procedure as in example 1 was repeated, except that the separator material was SUS as shown in Table 1.

Example 4

The procedure of example 1 was repeated, except that the separator material shown in Table 1 was a Ni metal surface layer-laminated PP film.

Example 5

The procedure of example 1 was repeated, except that the separator material was a Carbon Nanotube (CNT) thin film as shown in Table 1.

Example 6

< 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 separator >

And (3) obtaining an aluminum foil with the thickness of 15 microns, performing copper magnetron sputtering on one side of the aluminum foil, and coating homogeneous copper with the thickness of 15 microns on the surface layer to obtain the copper-aluminum-metal composite current collector.

< preparation of lithium ion Battery >

Then, the underside of the Cu — Al composite current collector (hereinafter, referred to as a separator) prepared as described above was placed on an electrode assembly a and compressed by applying an external force, wherein the underside of the separator had no electrode active material, a 15 μm PP separator was disposed between the underside of the separator and the electrode assembly a, and the separator was aligned with the edges of the top, bottom, and first side seals of the exterior package, and protruded from the second side seal of the exterior package, and the length of the protruded portion of the separator was 5 mm.

And placing an electrode assembly (hereinafter referred to as an electrode assembly B) on the upper side of the separator, enabling an outermost positive electrode plate to be in contact with the upper side of the separator, and applying external force to compress the electrode assembly, wherein the positive electrode plate is provided with a positive electrode active material, the upper side of the separator is provided with a negative electrode active material, and a 15-micron PP diaphragm is arranged between the positive electrode plate and the upper side of the separator. A positive electrode tab and a negative electrode tab are led out from the electrode component B, and a positive electrode tab is led out from the separator.

Then, the negative pole tab of the electrode component A and the positive pole tab of the electrode component B are welded together through laser welding to be connected in series, the positive pole tab of the separator and the serial pole tab are welded together through laser welding, and the connected pole tabs extend out of the outer package.

Then, another outer package (aluminum plastic film having a thickness of 90 μm) was placed face down over the electrode assembly B, and the other portions of the outer package were heat-sealed leaving the injection port side to obtain an assembled electrode in which two independent cavities were formed on both sides of the separator. Wherein the heat sealing temperature is 180 ℃ and the heat sealing pressure is 0.5 MPa.

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 7

Preparation of negative electrode sheet, preparation of positive electrode sheet, preparation of electrolyte, preparation of electrode assembly, and preparation of separator were the same as in example 3.

< preparation of lithium ion Battery >

One of the outer packages (aluminum plastic films having a thickness of 90 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. A positive electrode tab is drawn from the electrode assembly a.

Then, the stainless steel foil current collector (hereinafter, referred to as a separator) prepared as described above was placed on an electrode assembly a, and the separator was pressed by applying an external force such that the lower side of the separator was in contact with the outermost positive electrode sheet of the electrode assembly a, which was free of the electrode active material and free of the positive electrode active material. And the baffle aligns with the edge of the outer package top sealed edge, bottom sealed edge, first side sealed edge, stretches out from the second side sealed edge of the outer package, and the length of the baffle stretching out part is 5 mm.

And placing an electrode assembly (hereinafter referred to as an electrode assembly B) on the upper side of the separator, enabling an outermost positive electrode plate to be in contact with the upper side of the separator, and applying external force to compress the electrode assembly, wherein the positive electrode plate is provided with a positive electrode active material, the upper side of the separator is provided with a negative electrode active material, and a 15-micron PP diaphragm is arranged between the positive electrode plate and the upper side of the separator. A negative electrode tab is led out of the electrode assembly B and a negative electrode tab is led out of the separator.

Then, the positive electrode tab of the electrode assembly a, the negative electrode tab of the electrode assembly B, and the negative electrode tab of the separator were extended out of the exterior package.

Example 8

< preparation of separator >

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 >

Then, the polymer conductive current collector (hereinafter, referred to as a separator) prepared as described above was placed on an electrode assembly a, and the separator was pressed by applying an external force such that the lower side of the separator was in contact with the outermost negative electrode sheet of the electrode assembly a, which was provided with a positive electrode active material and a negative electrode active material, and a 15 μm PP separator was interposed between the negative electrode sheet and the lower side of the separator. And the baffle aligns with the edge of the outer package top sealed edge, bottom sealed edge, first side sealed edge, stretches out from the second side sealed edge of the outer package, and the length of the baffle stretching out part is 5 mm.

And placing an electrode assembly (hereinafter referred to as an electrode assembly B) on the upper side of the separator, enabling an outermost positive electrode plate to be in contact with the upper side of the separator, and applying external force to compress the electrode assembly, wherein the positive electrode plate is provided with a positive electrode active material, the upper side of the separator is provided with a negative electrode active material, and a 15-micron PP diaphragm is arranged between the positive electrode plate and the upper side of the separator. One negative tab is drawn from the electrode assembly B.

Example 9

The procedure of example 2 was repeated, except that the thickness of the separator was 6 μm as shown in Table 1.

Example 10

The procedure of example 1 was repeated, except that the thickness of the separator was 10 μm as shown in Table 1.

Example 11

The procedure of example 1 was repeated, except that the thickness of the separator was 15 μm as shown in Table 1.

Example 12

The procedure of example 1 was repeated, except that the thickness of the separator was 20 μm as shown in Table 1.

Example 13

The procedure of example 1 was repeated, except that the thickness of the separator was 40 μm as shown in Table 1.

Example 14

The procedure of example 1 was repeated, except that the thickness of the separator was changed to 100. mu.m as shown in Table 1.

Example 15

The same procedure as in example 3 was repeated, except that the separator had a 3mm protrusion length as shown in Table 1.

Example 16

The procedure was repeated in the same manner as in example 3 except that the separator had an extension of 10mm as shown in Table 1.

Example 17

The same procedure as in example 3 was repeated, except that the separator had a length of 20mm as shown in Table 1.

Example 18

The same procedure as in example 3 was repeated, except that the separator had a length of 30mm as shown in Table 1.

Example 19

The procedure was repeated in the same manner as in example 3 except that the thickness of the aluminum film was changed to 115 μm as shown in Table 1.

Example 20

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 >

Then, a separator (hereinafter, referred to as a separator a) having a length of 5mm in extension was placed on the electrode assembly a so as to be in contact with the electrode assembly a and compressed by applying an external force, wherein the separator a was aligned with the edges of the top and both side seals of the exterior pack and extended from the bottom seal of the exterior pack.

An electrode assembly (hereinafter, electrode assembly C) is placed on the separator a, is brought into contact with the separator a, and is pressed by applying an external force. A positive electrode tab and a negative electrode tab are drawn from the electrode assembly C.

And then a separator (hereinafter, referred to as a separator b) is placed on the electrode assembly C so as to be in contact with the electrode assembly C and compressed by applying an external force, wherein the separator b is aligned with the edges of the top and both side seals of the exterior pack and protrudes from the bottom seal of the exterior pack, and the length of the protruding portion of the separator b is 5 mm.

An electrode assembly (hereinafter, electrode assembly B) is placed on the separator B to be in contact with the separator B, and is pressed by applying an external force. A positive electrode tab and a negative electrode tab are drawn from the electrode assembly B.

Then, welding the negative pole tab of the electrode assembly A and the positive pole tab of the electrode assembly C together by laser welding to connect the two in series; and welding the negative electrode tab of the electrode component C and the positive electrode tab of the electrode component B together by laser welding so as to connect the two in series.

Then, the positive electrode tab of the electrode assembly A, the serial electrode tabs of the electrode assembly A and the electrode assembly C, the serial electrode tabs of the electrode assembly C and the electrode assembly B and the negative electrode tab of the electrode assembly B are extended out of the outer package.

Then, another outer package (aluminum plastic film having a thickness of 90 μm) was placed face down over the electrode assembly B, and the other portions of the outer package were heat-sealed leaving the injection port side to obtain an assembled electrode in which three independent cavities were formed on both sides of the separator. Wherein the heat sealing temperature is 180 ℃ and the heat sealing pressure is 0.5 MPa.

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

Example 21

< 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 for use.

< preparation of electrolyte 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 separator >

Same as in example 1.

< preparation of lithium ion Battery >

The same as example 1 was repeated, except that the electrode assembly was the above-described jelly-roll type electrode assembly.

The data and test results for examples 1-21 are shown in Table 1.

Comparative example 1

The same procedure as in example 1 was repeated, except that the separator was extended by 0mm as shown in Table 1.

The data and test results for comparative example 1 are shown in table 1.

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

It can be seen from examples 1 to 21 and comparative example 1 of the present application that the 2C discharge temperature rise during the use of the electrochemical device is significantly reduced by extending the separator from one of the outer package sealing edges.

Therefore, the electrochemical device provided by the application is separated into a plurality of independent sealing cavities by introducing the partition plate and hermetically connecting the partition plate with the outer package, so that ion isolation among different cavities is realized, the problem of internal short circuit is avoided, and the problem of electrolyte decomposition under high voltage is solved, thereby improving the use safety performance of the electrochemical device and ensuring the effective electric energy output of the electrochemical device. Meanwhile, the partition plate extends out of one side of the outer package seal edge, so that partial heat in the electrochemical device is conducted out through contact, and the overheating condition caused by accumulation of the heat of the electrochemical device in the using process is effectively avoided. If necessary, a heat sink may be provided at a portion of the separator extending out of the outer package, thereby further improving the heat dissipation capability of the electrochemical device.

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

Claims

An electrochemical device comprising an outer package, a separator and an electrode assembly disposed on both sides of the separator, respectively, the separator and the electrode assembly being located in the outer package, the separator protruding from one of the outer package sealing edges, the separator having a length of 3mm to 30mm protruding from the outer package sealing edge.
The electrochemical device of claim 1, wherein the separator extends from a bottom edge seal or a side edge seal of the overwrap seal.
The electrochemical device of claim 1, wherein the portion of the separator that protrudes out of the outer package is provided with a heat sink comprising a finned heat sink or a finned heat sink.
The electrochemical device according to claim 1, wherein the separator is connected to the exterior package, and sealed cavities are formed at both sides of the separator, respectively, each sealed cavity enclosing the electrode assembly and the electrolyte.
The electrochemical device of claim 1, wherein the electrode assemblies are provided with tabs of different polarities extending out of the overwrap, adjacent electrode assemblies being connected in series by the tabs.
The electrochemical device according to claim 1, wherein the material of the separator includes at least one of a polymer thin film, a metal foil, and a carbon material.
The electrochemical device according to claim 6, wherein each electrode assembly has two tabs of opposite polarities protruding out of the exterior package, and adjacent two electrode assemblies are connected in series by the tabs.
The electrochemical device of claim 1, wherein the separator is a bipolar separator comprising at least one of a Cu-Al composite current collector, a stainless steel foil current collector, or a polymeric conductive current collector.
The electrochemical device according to claim 8, wherein one side of the bipolar separator is provided with an electrode active material layer, the outermost layer of the electrode assembly adjacent to the electrode active material layer is provided with an electrode active material layer having an opposite polarity, a separator is disposed between the one side of the bipolar separator provided with the electrode active material layer and the adjacent electrode assembly, the other side of the bipolar separator is electrically insulated from the adjacent electrode assembly, and the bipolar separator leads out a tab connected to tabs of the electrode assemblies on both sides in series.
The electrochemical device according to claim 8, wherein one side of the bipolar separator is provided with an electrode active material layer, an outermost layer of the electrode assembly adjacent to the electrode active material layer is provided with an electrode active material layer having an opposite polarity, a separator is disposed between the side of the bipolar separator provided with the electrode active material layer and the adjacent electrode assembly, and the other side of the bipolar separator is electrically connected to the adjacent electrode assembly.
The electrochemical device according to claim 8, wherein electrode active material layers having different polarities are respectively disposed on both sides of the bipolar separator, electrode active material layers having opposite polarities are disposed on the outermost layer of the electrode assembly adjacent to each of the electrode active material layers, and a separator is disposed between the electrode active material layers of the bipolar separator and the electrode active material layers of the outermost layer of the electrode assembly.
The electrochemical device of claim 1, wherein the separator is sealingly coupled to the overwrap, and wherein the separator is encapsulated by the overwrap and comprises an encapsulating material comprising at least one of polypropylene, anhydride-modified polypropylene, polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid copolymer, ethylene-vinyl alcohol copolymer, polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, polyamide, polyester, amorphous alpha-olefin copolymer, and derivatives thereof.
The electrochemical device according to claim 1, wherein the separator has a thickness of 6 to 100 μm.
The electrochemical device of claim 1, having at least one of the following features:

a. the electrochemical device comprises 2 to 3 separators;

b. the thickness of the separator is 10 to 40 μm;

c. the length of the partition plate extending out of the outer package sealing edge is 5mm to 20 mm.
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 1-15.