Electrochemical device and electronic device including the same

Abstract

The present application relates to an electrochemical device and an electronic device including the electrochemical device. Specifically, the present application provides an electrochemical device, including an outer package, a partition, and electrode assemblies respectively arranged on both sides of the partition, wherein the partition and the electrode assembly are located in the outer package, the partition extends from one side of the seal edge of the outer package, and a heat dissipation device is arranged on the portion of the partition extending from the outer package. Through the design of the heat conduction mode of the partition, the overheating caused by the accumulation of heat during the use of the electrochemical device is effectively avoided.

Description

Technical Field

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

[0002] Lithium-ion batteries have many advantages such as high energy density, long cycle life, high nominal voltage, low self-discharge rate, small size, and light weight, and are widely used in the field of consumer electronics. With the rapid development of electric vehicles (EVs) and mobile electronic devices in recent years, people have higher and higher demands on battery energy density, safety, cycle performance, etc., and are looking forward to the emergence of new lithium-ion batteries with comprehensive performance improvements.

[0003] In the existing lithium-ion battery system, due to the limitations of the electrochemical system, such as the limited voltage difference between the positive and negative electrode materials and the limited anti-oxidation and reduction capacity of the electrolyte, the operating voltage of the lithium-ion battery is difficult to exceed 5V. However, in actual use, there are many scenarios where voltages exceeding 5V are required, such as electric vehicles (EV), voltage transformers (PT), energy storage systems (ESS) and other application scenarios.

[0004] In order to increase the output voltage of lithium-ion batteries, the existing technology usually connects multiple lithium-ion batteries in series while stacking them in the thickness direction. However, this series structure reduces the heat dissipation surface area due to the close contact between adjacent lithium-ion batteries in the thickness direction, which can easily lead to excessive temperature of the lithium-ion batteries, thereby causing overheating of the lithium-ion batteries and even causing safety accidents. Summary of the invention

[0005] The present application provides an electrochemical device and an electronic device comprising the electrochemical device to prevent overheating of the electrochemical device during use.

[0006] The first aspect of the present application provides an electrochemical device, comprising an outer package, a partition, and electrode assemblies respectively arranged on both sides of the partition, wherein the partition and the electrode assembly are located in the outer package, and the partition extends from one side of the sealing edge of the outer package, and the length of the partition extending from the sealing edge of the outer package is 3 mm to 30 mm.

[0007] In some embodiments of the present application, the partition extends from a bottom seal edge or a side seal edge of the outer packaging seal edge.

[0008] In some embodiments of the present application, the portion of the partition extending out of the outer package is provided with a heat dissipation device, and the heat dissipation device includes a plate-type heat sink or a fin-type heat sink.

[0009] In some embodiments of the present application, the separator is connected to the outer package, and sealed cavities are formed on both sides of the separator, and each sealed cavity encapsulates an electrode assembly and an electrolyte.

[0010] In some embodiments of the present application, the electrode assembly is provided with pole tabs of different polarities, the pole tabs extend out of the outer package, and adjacent electrode assemblies are connected in series via the pole tabs.

[0011] In some embodiments of the present application, the material of the separator includes at least one of a polymer film, a metal foil, and a carbon material.

[0012] In some embodiments of the present application, each electrode assembly has two electrode tabs with opposite polarities, the two electrode tabs extend out of the outer package, and two adjacent electrode assemblies are connected in series through the electrode tabs.

[0013] In some embodiments of the present application, the separator is a bipolar separator, and the bipolar separator includes at least one of a Cu-Al composite current collector, a stainless steel foil current collector, or a polymer conductive current collector.

[0014] In some embodiments of the present application, an electrode active material layer is provided on one side of the bipolar separator, and an electrode active material layer with opposite polarity is provided on the outermost layer of the electrode assembly adjacent to the electrode active material layer. A diaphragm is provided between the 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 insulated from the adjacent electrode assembly. The bipolar separator leads out a pole ear, which is connected to the pole ears of the electrode assemblies on both sides in series.

[0015] In some embodiments of the present application, an electrode active material layer is provided on one side of the bipolar separator, an electrode active material layer with opposite polarity is provided on the outermost layer of the electrode assembly adjacent to the electrode active material layer, a separator is provided 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.

[0016] In some embodiments of the present application, electrode active material layers of different polarities are provided on both sides of the bipolar separator, and the outermost layer of the electrode assembly adjacent to each electrode active material layer is provided with an electrode active material layer of opposite polarity, and a separator is provided between the electrode active material layer of the bipolar separator and the outermost electrode active material layer of the electrode assembly.

[0017] In some embodiments of the present application, the partition is sealed and connected to the outer package, and the portion where the partition is packaged with the outer package includes a packaging material, and the packaging material includes at least one of polypropylene, anhydride-modified polypropylene, polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid copolymer, ethylene-vinyl alcohol copolymer, polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, polyamide, polyester, amorphous α-olefin copolymer and its derivatives. In some embodiments of the present application, the thickness of the partition is 6μm to 100μm.

[0018] In some embodiments of the present application, it has at least one of the following features:

[0019] a. The electrochemical device comprises 2 to 3 separators;

[0020] b. The thickness of the separator is 10 μm to 40 μm;

[0021] c. The length of the partition extending from the sealing edge of the outer packaging is 5mm to 20mm.

[0022] In some embodiments of the present application, the structure of the electrode assembly includes at least one of a winding structure or a stacked structure.

[0023] A second aspect of the present application provides an electronic device, comprising the electrochemical device provided in the first aspect of the present application.

[0024] The electrochemical device provided by the present application separates the lithium-ion battery into a plurality of independent sealed cavities by introducing a partition and sealing the partition with the outer package, thereby realizing ion isolation between different sealed cavities, avoiding the safety hazards of internal short circuit or high-voltage decomposition of electrolyte, thereby improving the safety performance of the electrochemical device and ensuring the effective power output of the electrochemical device. At the same time, by extending the partition from one side of the sealed edge of the outer package, a heat dissipation device is provided at the part of the partition extending from the outer package, so as to realize the partial heat inside the electrochemical device to be discharged through contact heat transfer, and thus avoiding the overheating caused by the accumulation of heat in the electrochemical device during use. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present application and the prior art, the following briefly introduces the drawings required for use in the embodiments and the prior art. Obviously, the drawings described below are only some implementation methods of the present application. For ordinary technicians in this field, other implementation methods can also be obtained based on these drawings.

[0026] Figure 1 A top view of an electrochemical device according to one embodiment of the present application;

[0027] Figure 2 A schematic diagram of an electrochemical device according to an embodiment of the present application;

[0028] Figure 3 for Figure 2 Schematic diagram of the exploded structure of the electrochemical device;

[0029] Figure 4 A schematic diagram of an electrochemical device according to an embodiment of the present application;

[0030] Figure 5 for Figure 4 A partial schematic diagram of the internal structure cross section of an electrochemical device;

[0031] Figure 6 A partial schematic cross-sectional view of the internal structure of an electrochemical device according to an embodiment of the present application;

[0032] Figure 7 This is a partial schematic cross-sectional view of the internal structure of an electrochemical device according to one embodiment of the present application. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained based on the embodiments in the present application belong to the scope of protection of the present application.

[0034] The electrochemical device described in the present application is not particularly limited, and can be any electrochemical device that can use the present application, such as a lithium-ion battery, a sodium-ion battery, a magnesium-ion battery, a supercapacitor, etc. For the convenience of description, the following description is taken as an example of a lithium-ion battery, but this does not mean that the electrochemical device of the present application is limited to a lithium-ion battery.

[0035] In a first aspect, the present application provides an electrochemical device, comprising an outer package, a separator, and electrode assemblies respectively arranged on both sides of the separator, wherein the separator and the electrode assembly are located in the outer package, and the separator extends from one side of the sealing edge of the outer package;

[0036] The length of the partition extending from the sealed edge of the outer package is 3mm to 30mm, preferably 5mm to 20mm; when the length of the partition extending from the sealed edge of the outer package is less than 3mm, the protruding part of the partition is too short, the heat dissipation effect is poor, or it is difficult to fully and effectively connect with the heat dissipation device, thereby failing to achieve effective heat dissipation effect; when the length of the partition extending from the sealed edge of the outer package is greater than 30mm, the protruding part of the partition is too long, which will reduce the energy density of the electrochemical device.

[0037] Usually, the "outer packaging sealing edge" refers to the sealing area formed around the outer packaging after the outer packaging is sealed and packaged, wherein the sealing edge extending out of the side of the pole ear is the top sealing edge, the side opposite to the top sealing edge is the bottom sealing edge, and the two opposite sealing edges in the width direction of the outer packaging perpendicular to the top sealing edge are side sealing edges.

[0038] In the present application, the partition can extend from the bottom seal or the side seal of the outer packaging seal. The outer packaging seal includes two side seals. In one embodiment, the partition of the present application can extend from one of the two side seals. Figure 1 The “outer packaging seal edge” includes the bottom seal edge 52 and two side seal edges 51 , 53 , but does not include the top seal edge 54 .

[0039] In some embodiments of the present application, the specific number of separators included in the electrochemical device is not limited, and those skilled in the art can select according to actual needs, as long as the purpose of the present application can be achieved, for example, 2 to 3 separators are included.

[0040] In some embodiments of the present application, the portion of the partition extending out of the outer packaging is provided with a heat dissipation device. In the present application, there is no particular limitation on the type of the heat dissipation device, as long as the purpose of the present application can be achieved. For example, the heat dissipation device may include one of a plate type heat sink, a fin type heat sink, etc.

[0041] In some embodiments of the present application, the separator is connected to the outer package, and sealed cavities are formed on both sides of the separator, and each sealed cavity encapsulates an electrode assembly and an electrolyte.

[0042] In some embodiments of the present application, the partition is sealed and connected to the outer package, and sealed cavities are formed on both sides of the partition, each sealed cavity encapsulates an electrode assembly and an electrolyte, and ion insulation is achieved between the sealed cavities to avoid the problem of short circuit inside the electrochemical device and the problem of electrolyte decomposition under high voltage, thereby improving the safety performance of the electrochemical device and ensuring the effective power output of the electrochemical device. The partition extends from one side of the sealed edge of the outer package, and a heat dissipation device is provided at the portion of the partition extending from the outer package to achieve timely heat removal from the inside of the electrochemical device.

[0043] In some embodiments of the present application, the electrode assembly is provided with tabs of different polarities, the tabs extend out of the outer package, and adjacent electrode assemblies are connected in series through the tabs. When all the tabs provided in the electrode assembly are led out of the outer package for welding, the welding effect of the tabs can be monitored at any time, the risk of tab breakage can be reduced, and the problem of increased internal resistance of the electrochemical device due to poor tab welding effect can be avoided; adjacent electrode assemblies are connected in series, which can effectively increase the output voltage of the electrochemical device.

[0044] Figure 2 An embodiment of the present application is shown. Figure 3 yes Figure 2 Schematic diagram of the electrochemical device decomposition structure, see Figure 2 and Figure 3 The electrode assembly 31 and the electrode assembly 32 are separated by a partition 40, and the partition 40 extends from the side sealing edge 53. The partition part extending out of the outer package 10 is connected to an external heat dissipation device, so that the internal heat can be discharged. The partition 40 is sealed and connected to the outer package 10, and independent sealed cavities are formed on both sides of the partition 40. The sealed cavities are ion-insulated, and each sealed cavity contains an electrode assembly and an electrolyte. The negative electrode tab 22 of the electrode assembly 31 and the positive electrode tab 23 of the electrode assembly 32 extend out of the outer package 10 and are connected in series to form a tab 25. 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.

[0045] In some embodiments of the present application, the material of the separator includes at least one of a polymer film, a metal foil, and a carbon material.

[0046] The polymer film is not particularly limited as long as the present application can be achieved. For example, it may include at least one of polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate, polyetheretherketone, polyimide (PI), polyamide (PA), polyethylene glycol, polyamideimide, polycarbonate, cyclic polyolefin (PO), polyphenylene sulfide, polyvinyl acetate, polytetrafluoroethylene, polymethylene naphthalene, polyvinylidene fluoride, polyethylene naphthalate, polypropylene carbonate, poly(vinylidene fluoride-hexafluoropropylene), poly(vinylidene fluoride-co-chlorotrifluoroethylene), silicone resin, vinylon, polypropylene (PP), polyethylene (PE), polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, polyphenylene ether, polysulfone, amorphous α-olefin copolymer and its derivatives.

[0047] The metal foil is not particularly limited as long as the purpose of the present application can be achieved. For example, it can 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 their combinations or alloys. Preferably, a metal foil with good anti-oxidation and reduction properties in a lithium-ion battery environment can be selected. More preferably, a metal foil of a metal or alloy with good thermal conductivity can be selected.

[0048] The carbon material is not particularly limited as long as the purpose of the present application can be achieved. For example, it may include at least one of single-walled carbon nanotubes, multi-walled carbon nanotubes (MWCNTs), carbon felt, carbon film, carbon black, acetylene black, fullerene, conductive graphite film or graphene film.

[0049] In some embodiments of the present application, the separator is preferably made of a polymer film. Since the polymer film has a low density, the weight of the inactive material can be reduced, thereby increasing the mass energy density of the electrode assembly. In addition, the separator is made of a polymer material, which has a lower probability of generating debris under mechanical abuse (nail penetration, impact, extrusion, etc.) and has a better wrapping effect on the mechanically damaged surface, thereby improving the safety margin under the above-mentioned mechanical abuse and increasing the safety test pass rate.

[0050] In some embodiments of the present application, the material of the partition is preferably metal foil, which has strong isolation reliability, better toughness and density than polymer materials, and can be processed to a thinner thickness.

[0051] In some embodiments of the present application, the material of the partition is preferably carbon material, which has excellent safety performance, especially good thermal conductivity and excellent high-temperature reliability.

[0052] In some embodiments of the present application, the material of the separator may also include a composite material formed by combining 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 can be used as long as the purpose of the present application can be achieved, for example, it may include a Ni metal surface composite PP film, an Ag metal surface composite PET film, etc.

[0053] In some embodiments of the present application, each electrode assembly has two electrode tabs with opposite polarities, the two electrode tabs extend out of the outer package, and two adjacent electrode assemblies are connected in series through the electrode tabs.

[0054] In some embodiments of the present application, the separator is a bipolar separator, and the bipolar separator includes at least one of a Cu-Al composite current collector, a stainless steel foil current collector, or a polymer conductive current collector.

[0055] The polymer conductive current collector includes a composite material of a polymer material and a conductive material. The present application has no particular restrictions on the polymer conductive current collector, as long as the purpose of the present application can be achieved. For example, a polymer conductive current collector includes 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 that is 0° to 30° with the thickness direction of the polymer matrix. Another polymer conductive current collector includes conductive layers respectively arranged on two surfaces of the polymer matrix, and the two conductive layers are electrically connected. Another polymer conductive current collector includes a porous polymer matrix, and the conductive material is located in the pores of the porous polymer matrix, so that the two surfaces of the polymer conductive current collector are electronically conductive. Another typical example of a polymer conductive current collector is that the same or different metal material layers are respectively present on the two surfaces of the polymer material.

[0056] The present application has no particular restrictions on the preparation method of the polymer conductive current collector, as long as the purpose of the present application can be achieved. For example, it can be obtained by the following method: spraying a polymer material on a stainless steel substrate to obtain a polymer material layer, heating the polymer material layer to soften it, and then implanting a one-dimensional or two-dimensional conductive material, and then spraying the polymer material again to form a polymer material film, overheating and rolling the obtained polymer material film, removing the polymer material film from the surface of the stainless steel substrate with a scraper, and rolling it up to obtain the polymer conductive current collector.

[0057] The conductive material includes at least one of a carbon material or a metal material.

[0058] The polymer conductive current collector may also be formed by other methods, for example, by dispersing conductive agent particles in a polymer material.

[0059] In some embodiments of the present application, an electrode active material layer is provided on one side of the bipolar separator, an electrode active material layer of opposite polarity is provided on the outermost layer of the electrode assembly adjacent to the electrode active material layer, a diaphragm is provided between the 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 pole ear, which is connected to the pole ears of the electrode assemblies connected in series on both sides. In this embodiment, the first side of the bipolar separator and the outermost electrode sheet of the adjacent electrode assembly constitute an electrochemical unit, participate in the charge and discharge process of the electrochemical device, and improve the energy density of the electrochemical device. A pole ear is led out from the bipolar separator, which is connected to the pole ears of the electrode assemblies connected in series on both sides, thereby providing a high output voltage.

[0060] Figure 4 This is a schematic diagram of an electrochemical device according to another embodiment of the present application. Figure 5 for Figure 4A partial schematic diagram of the internal structure of the electrochemical device is shown in Figure 4 and Figure 5 The separator 40 of this embodiment is a bipolar separator, and a positive electrode active material layer 71 is provided on the A side of the bipolar separator, and a negative electrode active material layer 72 is provided on the outermost side of the electrode assembly 31 adjacent to the positive electrode active material layer 71, 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; there is no electrode active material layer on the B side of the bipolar separator, and a separator 80 is provided on the outermost layer of the electrode assembly 32 adjacent to it, so that the B side of the bipolar separator is electrically insulated from the adjacent electrode assembly 32; the bipolar separator leads out a positive electrode tab 27, and the negative electrode tab 22 of the electrode assembly 31 and the positive electrode tab 23 of the electrode assembly 32 are connected in series outside the outer package 10 to form a tab 25 (such as Figure 2 As shown in the figure, the positive electrode tab 27 is connected to the tab 25 to provide a high output voltage, 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. It can be understood by those skilled in the art that the positive electrode active material layer on the A surface of the bipolar separator can also be a negative electrode active material layer. In this case, the outermost layer of the electrode assembly adjacent to the A surface contains a positive electrode active material layer.

[0061] In some embodiments of the present application, an electrode active material layer is provided on one side of the bipolar electrode, an electrode active material layer of opposite polarity is provided on the outermost layer of the electrode assembly adjacent to the electrode active material layer, a membrane is provided between one side of the bipolar separator having 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.

[0062] In the present application, the above-mentioned "electrical connection" means that the side of the bipolar separator without electrode active material is connected to the circuit through physical contact with the outermost current collector of its adjacent electrode assembly, that is, there is no electrode active material on the surface of the electrode plate electrically connected to the bipolar separator.

[0063] In some embodiments of the present application, the bipolar separator may not have pole ears. In this case, the electrode assemblies on both sides of the bipolar separator are directly connected in series internally through the bipolar separator. The electrochemical device may only have two pole ears with opposite polarities. When the electrochemical device contains more than two electrode assemblies, all electrode assemblies are connected in series between the above two pole ears with opposite polarities through the bipolar separator.

[0064] In some embodiments of the present application, the bipolar separator may also lead out a pole ear, which is connected to the pole ear of the same polarity on the electrode assembly on one side of the bipolar separator provided with the electrode active material to form a parallel connection, and then connected to the pole ear of the opposite polarity on the electrode assembly on the other side to form a series connection. At this time, the two electrode assemblies can be connected in series through the inside of the bipolar separator and through the outside of the pole ear. In addition, the pole ear of the bipolar separator may not be connected to the pole ear of the electrode assembly, and is only used to monitor the voltage of the electrochemical device, so that the problematic electrode assembly can be checked in time, the cause of failure can be found, and the manufacturing rate and production efficiency of the electrochemical device can be improved.

[0065] Figure 6 A partial schematic diagram of the internal structure of an electrochemical device according to an embodiment of the present application is shown. Figure 6 As shown, the separator 40 of this embodiment is a bipolar separator, and a negative electrode active material layer 72 is provided on the A side of the bipolar separator, and a positive electrode active material layer 71 is provided on the outermost side of the electrode assembly 31 adjacent to the negative electrode active material layer 72, and a separator 80 is provided between the negative electrode active material layer 72 on the A side of the bipolar separator and the outermost positive electrode active material layer 71 of the adjacent electrode assembly 31; there is no electrode active material layer on the B side of the bipolar separator, and the outermost layer of the electrode assembly 32 adjacent to the B side of the bipolar separator is a positive electrode collector 61, and the positive electrode collector 61 is electrically connected to the B side of the bipolar separator 0. The electrode assembly 31 and the electrode assembly 32 can be directly connected in series through the 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 as positive and negative terminals for connection during charging and discharging. A negative electrode tab may also be provided on the bipolar separator, which is connected to the negative electrode tab of the electrode assembly 31 to form a parallel connection, and then connected to the positive electrode tab of the electrode assembly 32 to form a series connection. At this time, the two electrode assemblies 31 and 32 are connected in series both inside the bipolar separator and outside the tab. In addition, the tab on the bipolar separator may not be connected to the tab of the electrode assembly and is only used to monitor the voltage of the electrochemical device.

[0066] Those skilled in the art will appreciate that the negative electrode active material layer on the A side of the bipolar separator may also be a positive electrode active material layer. In this case, the outermost layer of the electrode assembly adjacent to the A side is provided with a negative electrode active material layer, and the outermost layer of the electrode assembly adjacent to the B side of the bipolar separator is a negative electrode current collector 62, and adjacent electrode assemblies may be directly connected in series through the bipolar separator.

[0067] In some embodiments of the present application, the bipolar separator is provided with electrode active material layers of different polarities on both sides, the outermost layer of the electrode assembly adjacent to each electrode active material layer is provided with an electrode active material layer of opposite polarity, and a separator is provided between the electrode active material layer of the bipolar separator and the outermost electrode active material layer of the electrode assembly. The bipolar separator is provided with electrode active material layers of different polarities on both sides, and the two sides form an electrochemical unit with the outermost electrode sheets of the adjacent electrode assemblies, further improving the energy density of the battery.

[0068] The electrode assemblies on both sides of the bipolar separator can be directly connected in series internally through the bipolar separator, or can be simultaneously connected in series internally and externally through the bipolar separator and two pole ears with opposite polarities.

[0069] Figure 7 A partial schematic diagram of the internal structure of an electrochemical device according to an embodiment of the present application is shown. Figure 7 As shown, the separator 40 of this embodiment is a bipolar separator, and a negative electrode active material layer 72 is provided on the A side of the bipolar separator, and the outermost layer of the electrode assembly 31 adjacent to the A side of the bipolar separator is a positive electrode active material layer 71, and the positive electrode active material layer 71 is provided on the B side of the bipolar separator, and the outermost layer of the electrode assembly 32 adjacent to the B side of the bipolar separator is a negative electrode active material layer 72, and a separator 80 is provided between the electrode active material layers on the A and B sides of the bipolar separator and the outermost layers of the electrode active material layers of the electrode assemblies adjacent thereto, respectively, and the electrode assembly 31 and the electrode assembly 32 are directly connected in series internally through the bipolar separator.

[0070] In some embodiments of the present application, the bipolar separator is provided with electrode active material layers of different polarities on both sides, and a tab is provided on the bipolar separator, and the tab can be used to monitor the voltage of the electrochemical device or to insulate the tab. The tab can also be connected to the series tabs of the electrode assemblies on both sides of the bipolar separator.

[0071] In some embodiments of the present application, the partition is sealed and connected to the outer package, and the portion where the partition is sealed with the outer package includes a packaging material, and the packaging material includes at least one of polypropylene, anhydride-modified polypropylene, polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid copolymer, ethylene-vinyl alcohol copolymer, polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, polyamide, polyester, amorphous α-olefin copolymer and derivatives thereof. The above packaging material can be more effectively sealed and connected to the outer package, thereby facilitating the improvement of the safety of the electrochemical device.

[0072] In the present application, the size of the seal edge formed after the partition and the outer packaging are packaged is not particularly limited, as long as the purpose of the present application can be achieved. For example, the thickness T (unit: mm) and width W (unit: mm) of the seal edge satisfy 0.01≤T / W≤0.05. The ratio of T / W within the above range can ensure that the battery is well sealed and the service life of the battery is improved. When T / W is too small, the seal thickness may be insufficient, the sealing effect is not good, and the environmental stability of the battery is reduced. For example, water vapor in the environment can easily penetrate into the battery, resulting in an increase in the moisture content in the battery, electrolyte decomposition, and a reduction in the service life of the battery; when the ratio of T / W is too large, the seal width W may be too small, and there is also a poor sealing effect, resulting in a reduction in the environmental stability of the battery. For example, water vapor in the environment can easily penetrate into the battery, resulting in an increase in the moisture content in the battery, electrolyte decomposition, and other problems, reducing the service life of the battery. In the present application, the seal thickness and seal width are not particularly limited, as long as the purpose of the present application can be achieved, for example, the width W of the seal edge is preferably 1mm to 7mm.

[0073] In the packaging process of the present application, the polymer material in the outer package and the polymer material in the sealing material are sealed together by heat pressing. Therefore, the seal thickness includes the thickness after the polymer material in the sealing material and the polymer material in the inner layer of the outer package are fused. The seal width refers to the width of the sealed area formed by combining the polymer material in the sealing material and the polymer material in the inner layer of the outer package after hot pressing. In some embodiments of the present application, the thickness of the partition is 6μm to 100μm, preferably 10μm to 40μm, and more preferably 20μm to 30μm. When the thickness of the partition is less than 6μm, the mechanical strength of the partition may be insufficient, which may easily cause damage and affect the performance and even safety of the electrochemical device; when its thickness is greater than 100μm, the mass of the introduced inactive substances increases, reducing the energy density of the electrochemical device.

[0074] In some embodiments of the present application, the structure of the electrode assembly includes at least one of a winding structure or a stacked structure.

[0075] In some embodiments of the present application, the structure of the electrode assembly is a winding structure, and the electrode assembly has at least one positive electrode tab and one negative electrode tab respectively extending from the positive electrode sheet and the negative electrode sheet.

[0076] In some embodiments of the present application, the structure of the electrode assembly is a stacked structure, and the electrode assembly includes multiple pole tabs, which can be a positive pole tab and a negative pole tab led out from each layer of the positive pole sheet and the negative pole sheet, respectively. Finally, an electrode assembly with a stacked structure contains multiple groups of positive pole tabs and negative pole tabs, and then the pole tabs are connected to lead out metal sheets through transfer welding.

[0077] In this application, the above-mentioned "tab" generally refers to a metal conductor drawn from the positive electrode sheet or the negative electrode sheet, which is used to connect other parts of the electrochemical device in series or in parallel. The positive tab is drawn from the positive electrode sheet, and the negative tab is drawn from the negative electrode sheet.

[0078] In the present application, the material of the tab is not particularly limited, as long as the purpose of the present application can be achieved. For example, the positive tab material includes at least one of aluminum (Al) or aluminum alloy, and the negative tab material includes at least one of nickel (Ni), copper (Cu) or copper-plated nickel (Ni-Cu).

[0079] In the present application, there is no particular limitation on the welding method of the tabs, as long as the purpose of the present application can be achieved, for example, at least one of laser welding, ultrasonic welding or resistance welding.

[0080] In the present application, the direction in which the tabs are led out is not particularly limited, as long as the purpose of the present application can be achieved. For example, the directions in which the tabs are led out can be in the same direction or in different directions.

[0081] In some embodiments of the present application, the electrode assembly may include a diaphragm, a positive electrode sheet, and a negative electrode sheet. The diaphragm is used to separate the positive electrode sheet and the negative electrode sheet, prevent the internal short circuit of the electrochemical device, allow the electrolyte ions to pass freely, and complete the electrochemical charge and discharge process. In the present application, the number of diaphragms, positive electrode sheets, and negative electrode sheets is not particularly limited, as long as the purpose of the present application can be achieved.

[0082] In some embodiments of the present application, the separator is not particularly limited as long as the purpose of the present application can be achieved. For example, at least one of polyethylene (PE) and polypropylene (PP)-based polyolefin (PO) separators, polyester films (such as 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 paper, rolled films, and spun films.

[0083] For example, the diaphragm 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 include at least one of polyethylene, polypropylene, polyethylene terephthalate and polyimide. Optionally, a polypropylene porous film, a polyethylene porous film, a polypropylene nonwoven fabric, a polyethylene nonwoven fabric or a polypropylene-polyethylene-polypropylene porous composite film may be used. Optionally, a surface treatment layer is provided 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 a mixed polymer and an inorganic substance.

[0084] For example, the inorganic layer includes inorganic particles and a binder, and the inorganic particles are not particularly limited, for example, they can be selected from at least one of aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide and barium sulfate. The binder is not particularly limited, for example, it can be selected from one or more combinations of polyvinylidene fluoride, copolymer of vinylidene fluoride-hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylic acid salt, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene and polyhexafluoropropylene. The polymer layer contains a polymer, and the material of the polymer includes at least one of polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylic acid salt, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride or poly (vinylidene fluoride-hexafluoropropylene) etc.

[0085] In some embodiments of the present application, the positive electrode sheet is not particularly limited, as long as the purpose of the present application can be achieved. For example, the positive electrode sheet generally includes a positive current collector and a positive active material. In the present application, the positive current collector is not particularly limited, and can be any positive current collector known in the art, such as copper foil, aluminum foil, aluminum alloy foil, and composite current collector. The positive active material is not particularly limited, and can be any positive active material of the prior art, for example, the positive active material includes at least one of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, or lithium manganese iron phosphate. In the present application, the thickness of the positive current collector and the positive active material is not particularly limited, as long as the purpose of the present application can be achieved. For example, the thickness of the positive current collector is 8μm to 12μm, and the thickness of the positive active material is 30μm to 120μm.

[0086] Optionally, the positive electrode sheet may further include a conductive layer, the conductive layer being located 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.

[0087] In some embodiments of the present application, the negative electrode sheet is not particularly limited, as long as the purpose of the present application can be achieved. For example, the negative electrode sheet generally includes a negative electrode current collector and a negative electrode active material. In the present application, the negative electrode current collector is not particularly limited, and any negative electrode current collector known in the art can be used, such as copper foil, aluminum foil, aluminum alloy foil, and composite current collector. The negative electrode active material is not particularly limited, and any negative electrode active material known in the art can be used. For example, it can include at least one of artificial graphite, natural graphite, mesophase carbon microspheres, silicon, silicon carbon, silicon oxides, soft carbon, hard carbon, lithium titanate, or niobium titanate. In the present application, the thickness of the negative electrode current collector and the negative electrode active material is not particularly limited, as long as the purpose of the present application can be achieved. For example, the thickness of the negative electrode current collector is 6μm to 10μm, and the thickness of the negative electrode active material is 30μm to 120μm.

[0088] Optionally, the negative electrode plate may further include a conductive layer, the conductive layer being located between the negative electrode current collector and the negative 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.

[0089] The conductive agent described above is not particularly limited, as long as the purpose of the present application can be achieved. For example, the conductive agent may include at least one of conductive carbon black (Super P), carbon nanotubes (CNTs), carbon fiber or graphene. The adhesive described above is not particularly limited, and any adhesive known in the art can be used, as long as the purpose of the present application can be achieved. For example, the adhesive may include at least one of styrene-butadiene rubber (SBR), polyvinyl alcohol (PVA), polytetrafluoroethylene (PTFE) or sodium carboxymethyl cellulose (CMC-Na). For example, the adhesive may be styrene-butadiene rubber (SBR).

[0090] In the present application, the electrolyte is not particularly limited as long as the purpose 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 non-aqueous solvent.

[0091] The lithium salt is not particularly limited as long as the purpose of the present application can be achieved. For example, the lithium salt may include at least one of LiPF6, LiBF4, LiAsF6, LiClO4, LiB(C6H5)4, LiCH3SO3, LiCF3SO3, LiN(SO2CF3)2, LiC(SO2CF3)3 or LiPO2F2. For example, the lithium salt may be LiPF6.

[0092] The non-aqueous solvent is not particularly limited as long as the purpose of the present application can be achieved. For example, the non-aqueous solvent may include at least one of carbonate compounds, carboxylate compounds, ether compounds, nitrile compounds, other organic solvents, and the like.

[0093] 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), ethyl methyl 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, trifluoromethylethylene carbonate, and the like.

[0094] In the present application, there is no particular limitation on the external packaging, as long as the purpose of the present application can be achieved.

[0095] For example, the outer packaging may include an inner layer and an outer layer, and the inner layer is sealed and connected to the bipolar current collector, so the material of the inner layer may include a polymer material, thereby achieving a good sealing effect; at the same time, the combination of the inner layer and the outer layer can effectively protect the internal structure of the electrochemical device. In the present application, there is no particular limitation on the material of the inner layer, as long as the purpose of the present application can be achieved. For example, the material of the inner layer includes at least one of polypropylene, polyester, p-hydroxybenzaldehyde, polyamide, polyphenylene ether, polyurethane, etc. In the present application, there is no particular limitation on the material of the outer layer, as long as the purpose of the present application can be achieved. For example, the material of the outer layer includes at least one of aluminum foil, aluminum oxide layer, silicon nitride layer, etc.

[0096] For example, the outer package may be an aluminum-plastic film, which comprises a nylon layer, an aluminum foil layer and a PP layer.

[0097] In the present application, there is no particular limitation on the thickness of the outer packaging, as long as the purpose of the present application can be achieved. For example, the thickness of the outer packaging can be 60 μm to 500 μm, preferably 60 μm to 300 μm, and more preferably 60 μm to 200 μm. The outer packaging of the above thickness can effectively protect the internal structure of the electrochemical device.

[0098] The present application has no particular restrictions on the sealing connection method between the partition and the outer packaging, as long as the purpose of the present application can be achieved. For example, the sealing method 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 purpose of the present application can be achieved. For example, for the polypropylene inner layer material, the hot pressing temperature is 150°C to 220°C, and the hot pressing pressure is 0.1MPa to 0.6MPa.

[0099] A second aspect of the present application provides an electronic device, which includes the electrochemical device provided in the first aspect of the present application.

[0100] The electronic devices described in the present application include general electronic devices in the art, such as laptop computers, pen-input computers, mobile computers, e-book players, portable phones, portable fax machines, portable copiers, portable printers, head-mounted stereo headphones, video recorders, LCD televisions, portable cleaners, portable CD players, mini CDs, transceivers, electronic notepads, calculators, memory cards, portable recorders, radios, backup power supplies, motors, cars, motorcycles, power-assisted bicycles, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries and lithium-ion capacitors, etc.

[0101] The terms used in this field are generally terms commonly used by those skilled in the art. If there is any inconsistency with the commonly used terms, the terms in this application shall prevail.

[0102] Test method:

[0103] 0.1C discharge energy density:

[0104] The electrochemical device was left at room temperature for 30 minutes, and then charged at a constant current of 0.05C to a voltage of 4.4V (rated voltage), and then discharged at a rate of 0.05C to 3.0V. The above charge / discharge steps were repeated for 3 cycles to complete the formation of the electrochemical device to be tested. After the formation of the electrochemical device was completed, it was charged at a constant current of 0.1C to a voltage of 4.4V, and then discharged at a discharge rate of 0.1C to 3.0V, and its discharge capacity was recorded, and then its energy density at 0.1C discharge was calculated:

[0105] Energy density (Wh / L) = discharge capacity (Wh) / electrochemical device volume size (L)

[0106] 2C discharge temperature rise:

[0107] Place the fully charged chemical device in the terminal heat sink, with one side in contact with the terminal heat sink and the other side exposed; stick a temperature probe on the surface of the exposed side to monitor the temperature of the electrochemical device; use adhesive tape to stick the partition part of the electrochemical device extending from the side to the heat sink, if there is no partition extending, do not process it; discharge with a 2C current for 15 minutes, and monitor the maximum value of its surface temperature.

[0108] The following examples and comparative examples are given to more specifically describe the embodiments of the present application. Various tests and evaluations were performed according to the following methods. In addition, unless otherwise specified, "%" and "parts" are based on mass.

[0109] Example 1

[0110] <Preparation of negative electrode sheet>

[0111] The negative electrode active material graphite, conductive carbon black (Super P), and styrene-butadiene rubber (SBR) are mixed in a weight ratio of 96:1.5:2.5, and then deionized water is added as a solvent to prepare a slurry with a solid content of 70%, and stirred evenly. The slurry is evenly coated on one surface of a negative electrode current collector copper foil with a thickness of 8μm, and dried at 110°C to obtain a negative electrode sheet with a single-sided coating of negative electrode active material and a coating thickness of 130μm. After the above steps are completed, the single-sided coating of the negative electrode sheet has been completed. After that, the above steps are repeated on the other surface of the negative electrode sheet to obtain a negative electrode sheet with a double-sided coating of negative electrode active material. After the coating is completed, the sheet is cut into a specification of 41mm×61mm for standby use.

[0112] <Preparation of positive electrode sheet>

[0113] The positive electrode active material lithium cobalt oxide (LiCoO2), conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) are mixed in a weight ratio of 97.5:1.0:1.5, and N-methylpyrrolidone (NMP) is added as a solvent to prepare a slurry with a solid content of 75%, and stirred evenly. The slurry is evenly coated on one surface of a positive electrode current collector aluminum foil with a thickness of 10μm, and dried at 90°C to obtain a positive electrode sheet with a coating thickness of 110μm. After the above steps are completed, the single-sided coating of the positive electrode sheet is completed. After that, the above steps are repeated on the other surface of the positive electrode sheet to obtain a positive electrode sheet with double-sided coating of positive electrode active materials. After the coating is completed, the sheet is cut into a specification of 38mm×58mm for standby use.

[0114] <Preparation of Electrolyte>

[0115] In a dry argon atmosphere, organic solvents ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) are first mixed in a mass ratio of EC:EMC:DEC=30:50:20, and then lithium salt lithium hexafluorophosphate (LiPF6) is added to the organic solvent to dissolve and mix evenly to obtain an electrolyte with a lithium salt concentration of 1.15 mol / L.

[0116] <Preparation of Electrode Assembly>

[0117] A 15 μm PP separator was placed between the positive electrode sheet and the negative electrode sheet prepared above, and the four corners were fixed after stacking to form a stacked electrode assembly, in which the number of layers of the positive electrode sheet and the negative electrode sheet were 13 and 14 respectively.

[0118] <Preparation of separator>

[0119] The encapsulation material polystyrene is uniformly dispersed in the dispersant N-methylpyrrolidone (NMP) to prepare a suspension of the encapsulation material; the encapsulation material is coated on the portion where the 30μm thick PP film of the partition and the outer packaging are encapsulated by a glue coating machine; the dispersant NMP in the suspension of the encapsulation material is dried at 130°C, and the preparation of the partition is completed. Among them, the melting point of the partition is 150°C, and the melting point of the encapsulation material is 240°C.

[0120] <Preparation of lithium-ion batteries>

[0121] A piece of outer packaging (aluminum-plastic film with a thickness of 90 μm) with a hole punched out is placed in an assembly fixture with the hole facing upward, and an electrode assembly (hereinafter referred to as electrode assembly A) is placed in the hole. A positive electrode tab and a negative electrode tab are led out from electrode assembly A.

[0122] Then, place the partition on the electrode assembly A so that it contacts the electrode assembly A and apply external force to press it, wherein the partition is aligned with the edges of the top seal, bottom seal and first side seal of the outer package, and extends from the second side seal of the outer package. The length of the protruding part of the partition is 5 mm.

[0123] An electrode assembly (hereinafter referred to as electrode assembly B) is placed on the separator so as to contact the separator and be pressed tightly by applying external force. A positive electrode tab and a negative electrode tab are led out from electrode assembly B.

[0124] Then, the negative electrode tab of electrode assembly A and the positive electrode tab of electrode assembly B are welded together by laser welding so that the two are connected in series, and the series-connected tabs are extended out of the outer packaging.

[0125] Then, the positive electrode tab of electrode assembly A and the negative electrode tab of electrode assembly B are extended out of the outer packaging.

[0126] Then, another outer package (aluminum-plastic film with a thickness of 90 μm) was placed with the pit side facing downward on the electrode assembly B, leaving the injection port side and heat-sealing the rest of the outer package to obtain an assembled electrode, wherein two independent cavities were formed on both sides of the separator. The heat-sealing temperature was 180°C and the heat-sealing pressure was 0.5 MPa.

[0127] The electrolyte is injected into the two cavities of the assembled electrode assembly separately, and then sealed.

[0128] The charging and discharging process only requires connecting the positive electrode tab of electrode assembly A and the negative electrode tab of electrode assembly B.

[0129] Example 2

[0130] Except that the separator material is Ti metal foil, the rest is the same as Example 1.

[0131] Example 3

[0132] The same as Example 1 except that the separator material is SUS.

[0133] Example 4

[0134] Except that the separator material is Ni metal surface composite PP film, the rest is the same as Example 1.

[0135] Example 5

[0136] Except that the separator material is a carbon nanotube (CNT) film, the rest is the same as Example 1.

[0137] Example 6

[0138] <Preparation of negative electrode sheet>, <Preparation of positive electrode sheet>, <Preparation of electrolyte>, and <Preparation of electrode assembly> are the same as those in Example 1.

[0139] <Preparation of separator>

[0140] An aluminum foil with a thickness of 15 μm is obtained, copper material is magnetron sputtered on one side of the aluminum foil, and a surface layer is coated with a uniform copper material with a thickness of 15 μm to obtain a copper-aluminum metal composite current collector.

[0141] <Preparation of lithium-ion batteries>

[0142] A piece of outer packaging (aluminum-plastic film with a thickness of 90 μm) with a hole punched out is placed in an assembly fixture with the hole facing upward, and an electrode assembly (hereinafter referred to as electrode assembly A) is placed in the hole. A positive electrode tab and a negative electrode tab are led out from electrode assembly A.

[0143] Then, the lower side of the Cu-Al composite current collector (hereinafter referred to as the separator) prepared as above is placed on the electrode assembly A and pressed tightly with external force, wherein there is no electrode active material on the lower side of the separator, and a 15μm PP separator is arranged between the lower side of the separator and the electrode assembly A, and the separator is aligned with the edges of the top seal, bottom seal and the first side seal of the outer packaging, and extends out from the second side seal of the outer packaging, and the length of the protruding part of the separator is 5mm.

[0144] An electrode assembly (hereinafter referred to as electrode assembly B) is placed on the upper side of the separator, so that the outermost positive electrode sheet is in contact with the upper side of the separator, and external force is applied to press tightly, wherein the positive electrode sheet is provided with positive electrode active material, the upper side of the separator is provided with negative electrode active material, and a 15μm PP separator is provided between the positive electrode sheet and the upper side of the separator. A positive electrode tab and a negative electrode tab are led out from electrode assembly B, and a positive electrode tab is led out from the separator.

[0145] Then, the negative electrode tab of electrode assembly A and the positive electrode tab of electrode assembly B are laser welded together to connect them in series, and the positive electrode tab of the separator is laser welded together with the above-mentioned series tabs, and the connected tabs are extended out of the outer packaging.

[0146] Then, the positive electrode tab of electrode assembly A and the negative electrode tab of electrode assembly B are extended out of the outer packaging.

[0147] Then, another outer package (aluminum-plastic film with a thickness of 90 μm) was placed with the pit side facing downward on the electrode assembly B, leaving the injection port side and heat-sealing the rest of the outer package to obtain an assembled electrode, wherein two independent cavities were formed on both sides of the separator. The heat-sealing temperature was 180°C and the heat-sealing pressure was 0.5 MPa.

[0148] The electrolyte is injected into the two cavities of the assembled electrode assembly separately, and then sealed.

[0149] The charging and discharging process only requires connecting the positive electrode tab of electrode assembly A and the negative electrode tab of electrode assembly B.

[0150] Example 7

[0151] <Preparation of negative electrode sheet>, <Preparation of positive electrode sheet>, <Preparation of electrolyte>, <Preparation of electrode assembly>, and <Preparation of separator> are the same as those in Example 3.

[0152] <Preparation of lithium-ion batteries>

[0153] A piece of outer packaging (aluminum-plastic film with a thickness of 90 μm) with a hole punched out is placed in an assembly fixture with the hole facing upward, and an electrode assembly (hereinafter referred to as electrode assembly A) is placed in the hole. A positive electrode tab is led out from electrode assembly A.

[0154] Then, the stainless steel foil current collector (hereinafter referred to as separator) prepared above is placed on the electrode assembly A, so that the lower side of the separator is in contact with the outermost positive electrode sheet of the electrode assembly A, and external force is applied to press tightly, wherein there is no electrode active material on the lower side of the separator, and the positive electrode sheet has no positive electrode active material. In addition, the separator is aligned with the edges of the top seal, bottom seal, and first side seal of the outer package, and extends from the second side seal of the outer package, and the length of the protruding part of the separator is 5 mm.

[0155] An electrode assembly (hereinafter referred to as electrode assembly B) is placed on the upper side of the separator, so that the outermost positive electrode sheet is in contact with the upper side of the separator, and external force is applied to press tightly, wherein the positive electrode sheet is provided with positive electrode active material, the upper side of the separator is provided with negative electrode active material, and a 15μm PP separator is provided between the positive electrode sheet and the upper side of the separator. A negative electrode ear is led out from the electrode assembly B, and a negative electrode ear is led out from the separator.

[0156] Then, the positive electrode tab of electrode assembly A, the negative electrode tab of electrode assembly B, and the negative electrode tab of the separator are extended out of the outer packaging.

[0157] Then, another outer package (aluminum-plastic film with a thickness of 90 μm) was placed with the pit side facing downward on the electrode assembly B, leaving the injection port side and heat-sealing the rest of the outer package to obtain an assembled electrode, wherein two independent cavities were formed on both sides of the separator. The heat-sealing temperature was 180°C and the heat-sealing pressure was 0.5 MPa.

[0158] The electrolyte is injected into the two cavities of the assembled electrode assembly separately, and then sealed.

[0159] The charging and discharging process only requires connecting the positive electrode tab of electrode assembly A and the negative electrode tab of electrode assembly B.

[0160] Example 8

[0161] <Preparation of negative electrode sheet>, <Preparation of positive electrode sheet>, <Preparation of electrolyte>, and <Preparation of electrode assembly> are the same as those in Example 1.

[0162] <Preparation of separator>

[0163] PET material is sprayed on a stainless steel substrate to obtain a PET layer, the PET layer is heated to soften it, and then a conductive material MWCNT is implanted, and then the PET material is sprayed again to form a PET film, the obtained PET film is overheated and rolled, and the PET film is removed from the surface of the stainless steel substrate with a scraper, and rolled up to obtain a polymer conductive current collector composed of PET and MWCNT.

[0164] <Preparation of lithium-ion batteries>

[0165] A piece of outer packaging (aluminum-plastic film with a thickness of 90 μm) with a hole punched out is placed in an assembly fixture with the hole facing upward, and an electrode assembly (hereinafter referred to as electrode assembly A) is placed in the hole. A positive electrode tab is led out from electrode assembly A.

[0166] Then, the polymer conductive current collector (hereinafter referred to as separator) prepared as above is placed on the electrode assembly A, so that the lower side of the separator is in contact with the outermost negative electrode sheet of the electrode assembly A, and external force is applied to compress it, wherein the lower side of the separator is provided with positive electrode active material, the negative electrode sheet is provided with negative electrode active material, and a 15μm PP separator is provided between the negative electrode sheet and the lower side of the separator. The separator is aligned with the edges of the top seal, bottom seal, and first side seal of the outer package, and extends from the second side seal of the outer package, and the length of the extended part of the separator is 5mm.

[0167] An electrode assembly (hereinafter referred to as electrode assembly B) is placed on the upper side of the separator, so that the outermost positive electrode sheet is in contact with the upper side of the separator, and external force is applied to press tightly, wherein the positive electrode sheet is provided with positive electrode active material, the upper side of the separator is provided with negative electrode active material, and a 15μm PP separator is provided between the positive electrode sheet and the upper side of the separator. A negative electrode ear is led out from electrode assembly B.

[0168] Then, the positive electrode tab of electrode assembly A and the negative electrode tab of electrode assembly B are extended out of the outer packaging.

[0169] Then, another outer package (aluminum-plastic film with a thickness of 90 μm) was placed with the pit side facing downward on the electrode assembly B, leaving the injection port side and heat-sealing the rest of the outer package to obtain an assembled electrode, wherein two independent cavities were formed on both sides of the separator. The heat-sealing temperature was 180°C and the heat-sealing pressure was 0.5 MPa.

[0170] The electrolyte is injected into the two cavities of the assembled electrode assembly separately, and then sealed.

[0171] The charging and discharging process only requires connecting the positive electrode tab of electrode assembly A and the negative electrode tab of electrode assembly B.

[0172] Example 9

[0173] The same as Example 2 except that the separator thickness is 6 μm.

[0174] Example 10

[0175] The same as in Example 1 except that the separator thickness is 10 μm.

[0176] Embodiment 11

[0177] The same as in Example 1 except that the separator thickness is 15 μm.

[0178] Example 12

[0179] The same as in Example 1 except that the separator thickness is 20 μm.

[0180] Example 13

[0181] The same as in Example 1 except that the separator thickness is 40 μm.

[0182] Embodiment 14

[0183] The process is the same as that of Example 1 except that the thickness of the separator is 100 μm.

[0184] Embodiment 15

[0185] Except that the extension length of the partition is 3 mm, the rest is the same as Example 3.

[0186] Example 16

[0187] Except that the extension length of the partition is 10 mm, the rest is the same as Example 3.

[0188] Embodiment 17

[0189] Except that the extension length of the partition is 20 mm, the rest is the same as Example 3.

[0190] Embodiment 18

[0191] Except that the extension length of the partition is 30 mm, the rest is the same as Example 3.

[0192] Embodiment 19

[0193] Except that the thickness of the aluminum-plastic film is 115 μm, the rest is the same as that of Example 3.

[0194] Embodiment 20

[0195] Except that the preparation process of the lithium ion battery is different from that in Example 1, the rest is the same as that in Example 1.

[0196] <Preparation of lithium-ion batteries>

[0197] A piece of outer packaging (aluminum-plastic film with a thickness of 90 μm) with a hole punched out is placed in an assembly fixture with the hole facing upward, and an electrode assembly (hereinafter referred to as electrode assembly A) is placed in the hole. A positive electrode tab and a negative electrode tab are led out from electrode assembly A.

[0198] Then place the separator (hereinafter referred to as separator a) on the electrode assembly A so that it contacts the electrode assembly A and apply external force to press it, wherein the separator a is aligned with the edges of the top seal and the two side seals of the outer package, and extends from the bottom seal of the outer package. The length of the protruding part of the separator a is 5 mm.

[0199] An electrode assembly (hereinafter referred to as electrode assembly C) is placed on separator a, so that it contacts separator a and is pressed tightly with external force. A positive electrode tab and a negative electrode tab are led out from electrode assembly C.

[0200] Then place the partition (hereinafter referred to as partition b) on the electrode assembly C so that it contacts the electrode assembly C and apply external force to press it, wherein the partition b is aligned with the edges of the top seal and the two side seals of the outer package, and extends from the bottom seal of the outer package. The length of the protruding part of the partition b is 5 mm.

[0201] An electrode assembly (hereinafter referred to as electrode assembly B) is placed on the separator b, so that it contacts the separator b and is pressed tightly with an external force. A positive electrode tab and a negative electrode tab are led out from the electrode assembly B.

[0202] Then, the negative electrode tab of electrode assembly A and the positive electrode tab of electrode assembly C are laser welded together so that the two are connected in series; the negative electrode tab of electrode assembly C and the positive electrode tab of electrode assembly B are laser welded together so that the two are connected in series.

[0203] Then, the positive electrode tab of electrode assembly A, the series-connected tabs of electrode assembly A and electrode assembly C, the series-connected tabs of electrode assembly C and electrode assembly B, and the negative electrode tab of electrode assembly B are extended out of the outer packaging.

[0204] Then, another outer package (aluminum-plastic film with a thickness of 90 μm) was placed with the pit side facing downward on the electrode assembly B, leaving the injection port side and heat-sealing the rest of the outer package to obtain an assembled electrode, wherein three independent cavities were formed on both sides of the separator. The heat-sealing temperature was 180°C and the heat-sealing pressure was 0.5 MPa.

[0205] The electrolyte is injected into the three cavities of the assembled electrode assembly separately, and then sealed.

[0206] The charging and discharging process only requires connecting the positive electrode tab of electrode assembly A and the negative electrode tab of electrode assembly B.

[0207] Embodiment 21

[0208] <Preparation of negative electrode sheet>

[0209] Except for cutting the negative electrode sheet into a size of 465 mm×92 mm for use, the rest is the same as Example 1.

[0210] <Preparation of positive electrode sheet>

[0211] Except for cutting the positive electrode sheet into a size of 480 mm×90 mm for standby use, the rest is the same as Example 1.

[0212] <Preparation of Electrolyte>

[0213] Same as Example 1.

[0214] <Preparation of Electrode Assembly>

[0215] The positive electrode sheet and negative electrode sheet prepared above, as well as the 15 μm PP separator, are stacked in the order of positive electrode sheet, separator, and negative electrode sheet, with the separator placed between the positive electrode sheet and the negative electrode sheet to play an isolating role, and then wound to obtain a wound electrode assembly.

[0216] <Preparation of separator>

[0217] Same as Example 1.

[0218] <Preparation of lithium-ion batteries>

[0219] Except that the electrode assembly is the above-mentioned wound electrode assembly, the rest is the same as Example 1.

[0220] The data and test results of Examples 1-21 are shown in Table 1.

[0221] Comparative Example 1

[0222] Except that the extension length of the partition is 0 mm, the rest is the same as Example 1.

[0223] The data and test results of Comparative Example 1 are shown in Table 1.

[0224] Table 1 Preparation parameters and test results of each embodiment and comparative example

[0225]

[0226] It can be seen from Examples 1-21 of the present application and Comparative Example 1 that by extending the partition from one of the sealed edges of the outer package, the 2C discharge temperature rise of the electrochemical device during use is significantly reduced.

[0227] It can be seen that the electrochemical device provided by the present application is divided into multiple independent sealed cavities by the introduction of the partition and the sealed connection between the partition and the outer packaging, so as to achieve ion isolation between different cavities, avoid internal short circuit problems, and the problem of electrolyte decomposition under high voltage, thereby improving the safety performance of the electrochemical device and ensuring the effective power output of the electrochemical device. At the same time, by extending the partition from one of the sealed edges of the outer packaging, part of the heat inside the electrochemical device is extracted through contact heat transfer, effectively avoiding overheating caused by the accumulation of heat in the electrochemical device during use. If necessary, a heat dissipation device can be set on the part of the partition extending from the outer packaging to further improve the heat dissipation capacity of the electrochemical device.

[0228] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. An electrochemical device, comprising an outer package, a partition, and electrode assemblies respectively arranged on both sides of the partition, wherein the partition and the electrode assembly are located in the outer package, the outer package comprises an outer package sealing edge, the partition extends from one side of the outer package sealing edge, the length of the partition extending from the outer package sealing edge is 3 mm to 30 mm, and a heat dissipation device is provided on the portion of the partition extending from the outer package.

2. The electrochemical device according to claim 1, wherein: The partition extends from the bottom seal edge or the side seal edge of the outer packaging seal edge.

3. The electrochemical device according to claim 1, wherein The heat dissipation device includes a plate-type heat sink or a fin-type heat sink.

4. The electrochemical device according to claim 1, wherein The separator is connected to the outer package, and sealed cavities are formed on both sides of the separator through the sealing edge of the outer package, and each sealed cavity encapsulates the electrode assembly and the electrolyte.

5. The electrochemical device according to claim 1, wherein The electrode assembly is provided with pole tabs of different polarities, the pole tabs extend out of the outer package, and adjacent electrode assemblies are connected in series through the pole tabs.

6. The electrochemical device according to claim 1, wherein The material of the separator includes at least one of a polymer film, a metal foil, and a carbon material.

7. The electrochemical device according to claim 6, wherein: Each electrode assembly has two tabs with opposite polarities, the two tabs protrude from the outer package, and two adjacent electrode assemblies are connected in series through the tabs.

8. The electrochemical device according to claim 1, wherein The separator is a bipolar separator, and the bipolar separator includes at least one of a Cu-Al composite current collector, a stainless steel foil current collector or a polymer conductive current collector.

9. The electrochemical device according to claim 8, wherein: An electrode active material layer is provided on one side of the bipolar separator, and an electrode active material layer with opposite polarity is provided on the outermost layer of the electrode assembly adjacent to the electrode active material layer. A diaphragm is provided between the 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 insulated from the adjacent electrode assembly. The bipolar separator leads out a pole ear, which is connected to the pole ears of the electrode assemblies on both sides in series.

10. The electrochemical device according to claim 8, wherein An electrode active material layer is provided on one side of the bipolar separator, and an electrode active material layer with opposite polarity is provided on the outermost layer of the electrode assembly adjacent to the electrode active material layer. A diaphragm is provided between the 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.

11. The electrochemical device according to claim 8, wherein Electrode active material layers of different polarities are respectively arranged on both sides of the bipolar separator, and the outermost layer of the electrode assembly adjacent to each electrode active material layer is arranged with an electrode active material layer of opposite polarity, and a separator is arranged between the electrode active material layer of the bipolar separator and the outermost electrode active material layer of the electrode assembly.

12. The electrochemical device according to claim 1, wherein The partition is sealed and connected to the outer package, and the portion where the partition and the outer package are packaged includes a packaging material, and the packaging material includes at least one of polypropylene, anhydride-modified polypropylene, polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid copolymer, ethylene-vinyl alcohol copolymer, polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, polyamide, polyester, amorphous α-olefin copolymer and its derivatives.

13. The electrochemical device according to claim 1, wherein The separator has a thickness of 6 μm to 100 μm.

14. The electrochemical device according to 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 μm to 40 μm; c. The length of the partition extending from the sealing edge of the outer packaging is 5mm to 20mm.

15. The electrochemical device according to claim 1, wherein The structure of the electrode assembly includes at least one of a winding structure and a stacked structure.

16. An electronic device comprising the electrochemical device according to any one of claims 1 to 15.

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