CN114730966A

CN114730966A - Electrochemical device and electric equipment

Info

Publication number: CN114730966A
Application number: CN202180006432.1A
Authority: CN
Inventors: 张益博
Original assignee: Ningde Amperex Technology Ltd
Current assignee: Ningde Amperex Technology Ltd
Priority date: 2021-06-22
Filing date: 2021-06-22
Publication date: 2022-07-08
Also published as: WO2022266866A1

Abstract

An electrochemical device (100) and an electric apparatus (200), the electrochemical device (100) comprising a separator (30) and a plurality of electrode assemblies (50) within a case (10), the separator (30) comprising a heating element (301). This electrochemical device (100) and consumer (200), with inside heating element (301) embedding baffle (30), except can realizing the ion insulation function of baffle (30) and guaranteeing the reliability of encapsulation, simultaneously can also utilize heating element (301) of intermediate level to realize electrochemical device's (100) heating function, effectively improved among the prior art baffle (30) mechanical strength, the not good problem of thermal stability, simultaneously, the energy density that has improved among the prior art that the internal heating mode leads to reduces, the self discharge problem is serious, there is reliability risk scheduling problem.

Description

Electrochemical device and electric equipment

Technical Field

The present application relates to the field of battery technology, and more particularly, to an electrochemical device and an electric device.

Background

Currently, a multi-cell series connection method is generally adopted to increase the output voltage, but the multi-cell series connection method has a plurality of problems, such as: the inter-cell capacity difference results in a lower overall Energy Density (ED); extra electronic resistance can be introduced by the series connection lead and the contact resistor, and energy is wasted due to heating; higher voltages require a greater number of batteries, increasing the difficulty of battery management, etc. In order to solve the above problems, a concept of a high output voltage battery is proposed. In order to realize the design concept of the high-output voltage battery, the electrode assemblies need to be assembled in series, and the separators in the series structure need to realize the ion insulation function (ion non-conduction) of the series cavities, so that internal short circuit of cathodes and anodes with different potentials is avoided, and decomposition failure of electrolyte under high voltage is avoided. In addition, as part of the package structure, the mechanical strength, thermal stability, and other parameters of the spacer are required to meet certain requirements.

The lithium ion battery has poor dynamics under the low-temperature condition, so that the low-temperature charging capability is poor, and the serious lithium precipitation of the anode occurs during the high-rate charging in the low-temperature environment of the battery, thereby causing safety risk; meanwhile, under the low temperature condition, the electrode material has low activity, so that the capacity exertion is low and the energy density loss is caused. In a low-temperature environment, the battery is heated, the dynamics of a battery chemical system is improved, and the problems of low capacity and lithium precipitation of an anode of the lithium ion battery in the low-temperature environment can be effectively solved. The common external heating mode has the disadvantages that the heating rate is low in the heating process, the temperature difference between all parts of the battery is large, the influence on electrode materials is large, the cycle performance of the battery is deteriorated, and the safety and reliability risks exist. The heating plate heat source is embedded into the battery, and the battery is heated, so that the heating rate is high, the temperature difference between parts of the battery is small, and the damage to the battery is small. However, the embedding of the heating plate has the problems of reduced energy density, interface contact degradation, serious self-discharge problem, reliability risk in drop test and the like, and an innovative scheme is urgently needed to be developed to solve the problems.

Disclosure of Invention

In view of the above, the present application provides a novel electrochemical device and an electrical apparatus to optimize the performance of a separator of a high output voltage battery, and simultaneously improve the problems of reduced energy density, degraded interface contact, severe self-discharge problem, reliability risk in drop test, and the like caused by a heating element inside the battery.

A first aspect of the present application provides an electrochemical device comprising a separator and a plurality of electrode assemblies within a housing, the separator comprising a heating element. With heating element embedding baffle inside, except that can realize the ion insulation function of baffle and guarantee the reliability of encapsulation, the heating element that can also utilize the intermediate level simultaneously realizes electrochemical device's heating function, has effectively improved baffle mechanical strength among the prior art, the not good problem of thermal stability, simultaneously, has improved among the prior art energy density reduction, the self-discharge problem that the internal heating mode leads to and serious, have reliability risk scheduling problem.

In some embodiments, the plurality of electrode assemblies are respectively disposed in a plurality of cavities within the case separated by the separators.

In some embodiments, the electrochemical device further comprises a first terminal and a second terminal electrically connected to the heating element, the first terminal and the second terminal having a first resistance R1 therebetween, satisfying: r1 is more than or equal to 5m omega. Further, R1 is not less than 20m Ω. When the temperature of the electrochemical device is lower than the normal operation temperature (e.g., lower than about 5 ℃), the first terminal and the second terminal will be connected to the heating circuit and heat the electrochemical device, and since the resistance R1 is much greater than the internal resistance of the electrochemical device during normal operation and the current of the heating circuit can be conveniently increased during charging, the internal temperature of the electrochemical device will be rapidly increased, and thus the electrochemical performance of the electrochemical device can be rapidly improved.

In some embodiments, the electrode assembly comprises a first tab and a second tab with opposite polarities, and the first tab and the second tab in the same electrode assembly have an internal resistance R therebetween, so that: R1/R is more than or equal to 0.05 and less than or equal to 5000. Further, 1 ≦ R1/R ≦ 1000.

In some embodiments, at least one of the first tabs is electrically connected to the first terminal.

In some embodiments, at least two electrode assemblies are connected in series.

In some embodiments, the separator further comprises an insulating layer on at least one side of the heating element. The separator adopts the structure, compared with a metal-based current collector, the separator has the advantages that the probability of generating conductive debris is lower under mechanical abuse conditions (nail penetration, impact, extrusion and the like), and the wrapping effect on the damaged surface of a machine is better, so that the safety boundary under the mechanical abuse conditions can be improved, and the safety test passing rate is improved.

In some embodiments, the heating element comprises a patterned shape.

In some embodiments, the material of the insulating layer includes at least one of a polymer or an inorganic insulating material.

In some embodiments, the separator further comprises an encapsulation layer on a surface of the insulating layer.

In some embodiments, the interfacial adhesion force F between the separator and the shell satisfies: f is more than or equal to 10N/cm.

In some embodiments, the patterned shape includes a plurality of first portions arranged in parallel, two adjacent first portions are connected by a second portion, and two adjacent first portions are arranged at intervals; an insulator is arranged between the adjacent first parts, and the material of the insulator comprises at least one of polymer or inorganic insulating material.

In some embodiments, the material of the encapsulation layer includes at least one of polypropylene, anhydride modified polypropylene, polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate, 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, the polymer comprises polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyetheretherketone, polyimide, polyamide, polyethylene glycol, polyamideimide, polycarbonate, cyclic polyolefin, polyphenylene sulfide, polyvinyl acetate, polytetrafluoroethylene, polymethylene naphthalene, polyvinylidene fluoride, polyethylene naphthalate, polypropylene carbonate, poly (vinylidene fluoride-hexafluoropropylene), poly (vinylidene fluoride-co-chlorotrifluoroethylene), silicone, vinylon, polypropylene, anhydride-modified polypropylene, polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate, ethylene-acrylic acid copolymer, ethylene-vinyl alcohol copolymer, polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, polyethylene terephthalate, and polyethylene terephthalate, and polyethylene terephthalate, polyethylene terephthalate, At least one of polyphenylene ether, polyester, polysulfone, amorphous alpha-olefin copolymer, and derivatives thereof.

In some embodiments, the inorganic insulating material comprises at least one of hafnium oxide, strontium titanate, tin oxide, cerium oxide, magnesium oxide, nickel oxide, calcium oxide, barium oxide, zinc oxide, zirconium dioxide, yttrium oxide, aluminum oxide, titanium dioxide, silicon dioxide, boehmite, magnesium hydroxide, or aluminum hydroxide.

In some embodiments, the material of the heating element comprises at least one of a carbon material or a metal material.

In some embodiments, the thickness H of the separator satisfies: h is more than or equal to 2 mu m.

In some embodiments, the carbon material comprises at least one of a carbon felt, a carbon film, carbon black, acetylene black, a fullerene, a conductive graphite film, or a graphene film; the metal material comprises at least one of nickel, titanium, copper, silver, gold, platinum, iron, cobalt, chromium, tungsten, molybdenum, aluminum, magnesium, potassium, sodium, calcium, strontium, barium, silicon, germanium, tin, lead, indium, zinc or stainless steel.

The second aspect of the present application also provides a powered device comprising the electrochemical device as described above.

In some embodiments, the powered device further comprises a switch. When the temperature is below T1 or above T2, the switch is closed, allowing current to pass through the heating element.

In some embodiments, T1 is 5 ℃ and T2 is 50 ℃.

The application provides an electrochemistry device and consumer, with inside heating element imbeds the baffle, except can realizing the ion insulation function of baffle and guaranteeing the reliability of encapsulation, the heating element that simultaneously can also utilize the intermediate level realizes electrochemistry device's heating function, effectively improved among the prior art baffle mechanical strength, the not good problem of thermal stability, simultaneously, the energy density that the internal heating mode leads to among the prior art has been improved and has been reduced, the self-discharge problem is serious, there is reliability risk scheduling problem.

Drawings

The present application will be described in further detail with reference to the following drawings and detailed description.

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

Fig. 2 is a schematic structural diagram of a separator according to an embodiment of the present application.

Fig. 3 is a schematic structural diagram of a separator according to an embodiment of the present application.

Fig. 4 is a schematic structural diagram of a heating element according to an embodiment of the present application.

Fig. 5 is a schematic structural diagram of a separator according to an embodiment of the present application.

Fig. 6 is a schematic structural diagram of a separator according to an embodiment of the present application.

Fig. 7 is a block diagram of an electric device according to an embodiment of the present disclosure.

Description of the main element symbols:

electrochemical device 100

Power utilization device 200

Housing 10

Partition board 30

Electrode assembly 50

First electrode assembly 51

Second electrode assembly 52

Heating element 301

Insulating layer 302

Encapsulation layer 303

Insulator 304

First tab 501

Second tab 502

First terminal 3010

Second terminal 3014

First part 3011

Second part 3012

The following detailed description will further describe embodiments of the present application in conjunction with the above-described figures.

Detailed Description

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the embodiments of this application belong. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the embodiments of the present application.

It should be noted that all the directional indications (such as up, down, left, right, front, and rear … …) in the embodiment of the present application are only used to explain the relative position relationship between the components, the movement situation, and the like in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indication is changed accordingly.

In addition, descriptions in this application as to "first", "second", etc. are for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicit to the technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the feature. In the description of the present application, "plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In this application, the terms "connected," "fixed," and the like are to be construed broadly and unless otherwise expressly stated or limited to, for example, "fixed" may be fixedly connected or detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be interconnected within two elements or in a relationship where two elements interact with each other unless otherwise specifically limited. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.

Referring to fig. 1, the present application provides an electrochemical device 100 including a case 10, at least one separator 30, and a plurality of electrode assemblies 50. The at least one separator 30 partitions the interior of the case 10 into a plurality of cavities in which the plurality of electrode assemblies 50 are respectively disposed. In the present embodiment, the number of the separators 30 is one, and the plurality of electrode assemblies 50 includes a first electrode assembly 51 and a second electrode assembly 52. The first electrode assembly 51 and the second electrode assembly 52 are respectively disposed in two cavities separated by the separator 30 within the case 10, and the separator 30 includes a heating element 301 (see fig. 2). It is understood that N separators 30 may partition the case 10 to form N +1 cavities, and N +1 electrode assemblies may be respectively located in the formed N +1 cavities. The electrode assembly 50 may be a wound or laminated structure, and the present application is not limited thereto.

As shown in fig. 1, the electrochemical device 100 further includes a first terminal 3010 and a second terminal 3014 electrically connected to the heating element 301, the first terminal 3010 and the second terminal 3014 having a first resistance R1 therebetween, satisfying: r1 is more than or equal to 5m omega.

When the temperature of the electrochemical device 100 is lower than the normal operation temperature (e.g., lower than about 5 ℃), the first terminal 3010 and the second terminal 3014 will connect to the heating circuit and heat the electrochemical device 100, since the resistance R1 can be much larger than the internal resistance of the electrochemical device during normal operation and the current of the heating circuit can be conveniently increased during charging, the internal temperature of the electrochemical device 100 will be rapidly increased, and thus the electrochemical performance of the electrochemical device 100 can be rapidly improved.

As shown in fig. 1, the first electrode assembly 51 includes a first tab 501 and a second tab 502 of opposite polarity. An internal resistance R is arranged between the first electrode lug 501 and the second electrode lug 502, and the following requirements are met: R1/R is more than or equal to 0.05 and less than or equal to 5000. Further, 1 ≦ R1/R ≦ 1000.

Further, at least one of the first tabs 501 is electrically connected to the first terminal 3010.

In some embodiments, at least two electrode assemblies 50 are connected in series. In fig. 1, a first tab 501 of the first electrode assembly 51 is connected to a second tab 502 of the second electrode assembly 52 to realize series connection.

Referring to fig. 2, the spacer 30 includes a heating element 301 and an insulating layer 302, wherein the insulating layer 302 is disposed on at least one side of the heating element 301. In fig. 2, the case where the insulating layer 302 is located on opposite sides (in the thickness direction of the separator 30) of the heating element 301 is shown, the insulating layer 302 may be located on only one side of the heating element 301. With the above structure of the separator 30, the separator 30 has a smaller probability of generating conductive debris and a better wrapping effect on a damaged surface of a machine in the case of mechanical abuse (piercing, impacting, extruding, etc.) than a metal-based current collector, so that a safety margin in the case of mechanical abuse can be improved, and a safety test throughput can be improved.

Further, the spacer 30 further includes an encapsulation layer 303 on the surface of the insulating layer 302. In fig. 2, the encapsulation layer 303 is located at an end edge of the insulating layer 302 for encapsulation, that is, a main surface portion of the insulating layer 302 is not covered by the encapsulation layer 303 and is exposed outside the partition board 30. The area of the encapsulation layer 303 is reduced as much as possible, and the proportion of non-effective substances is reduced, so that the energy density of the electrochemical device can be improved. It is understood that the encapsulation layer 303 may also cover the insulating layer 302 entirely so that the main surface thereof is not exposed, as shown in fig. 3.

In some embodiments, the material of the sealing layer 303 has a low melting point, and can be used as a material for sealing the housing, and the materials of the heating element 301 and the sealing layer 303 both have characteristics of good ion insulation capability, certain thermal stability, and the like. The melting point (softening point) of the heating element 301 is greater than 130 c, preferably greater than 150 c. The melting point (softening point) of the encapsulating layer 303 ranges from 120 ℃ to 240 ℃, preferably from 130 ℃ to 170 ℃. Furthermore, the melting point of the heating element 301 is at least 10 ℃, preferably more than 20 ℃, higher than the melting point (softening point) of the encapsulation layer 303, so as to ensure the reliability of the encapsulation and the effectiveness of the ionic insulation.

Further, the material of the encapsulation layer 303 includes at least one of polypropylene, anhydride modified polypropylene, polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate, ethylene-acrylic acid copolymer, ethylene-vinyl alcohol copolymer, polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, polyamide, polyester, amorphous α -olefin copolymer, and derivatives thereof. The material of the heating element 301 includes at least one of a carbon material or a metal material. The carbon material comprises at least one of a carbon felt, a carbon film, carbon black, acetylene black, fullerene, a conductive graphite film, or a graphene film; the metal material includes at least one of nickel (Ni), titanium (Ti), copper (Cu), silver (Ag), gold (Au), platinum (Pt), iron (Fe), cobalt (Co), chromium (Cr), tungsten (W), molybdenum (Mo), aluminum (Al), magnesium (Mg), potassium (K), sodium (Na), calcium (Ga), strontium (Sr), barium (Ba), silicon (Si), germanium (Ge), tin (Sb), lead (Pb), indium (In), zinc (Zn), or stainless steel.

Referring to fig. 4, the heating element 301 includes a patterned shape, and the patterned shape includes a plurality of first portions 3011 arranged in parallel, and two adjacent first portions 3011 are connected by a second portion 3012. In fig. 4, the patterned shape of the heating element 301 is shown as a continuous zigzag shape, and the patterned shape of the heating element may be other shapes, for example, two adjacent first portions 3011 are arranged in parallel at intervals, etc. The heating element 301 may also not include the patterned shape, which may be a unitary piece of a complete continuous conductive material.

Further, an insulator 304 is provided between adjacent first portions 3011. The material of the insulating layer 302 includes at least one of a polymer and an inorganic insulating material, and the material of the insulator 304 includes at least one of a polymer and an inorganic insulating material. The insulator 304 and the insulating layer 302 ensure ion insulation on both sides of the separator 30.

Further, the polymer includes polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyetheretherketone, polyimide, polyamide, polyethylene glycol, polyamideimide, polycarbonate, cyclic polyolefin, polyphenylene sulfide, polyvinyl acetate, polytetrafluoroethylene, polymethylene naphthalene, polyvinylidene fluoride, polyethylene naphthalate, polypropylene carbonate, poly (vinylidene fluoride-hexafluoropropylene), poly (vinylidene fluoride-co-chlorotrifluoroethylene), silicone, vinylon, polypropylene, anhydride-modified polypropylene, polyethylene, ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate (EEA), ethylene-acrylic acid copolymer (EAA), ethylene-vinyl alcohol copolymer (EVAL), polyvinyl chloride, polystyrene, polyethylene terephthalate, polyethylene naphthalate, polypropylene, polyethylene naphthalate, polypropylene terephthalate, polyethylene naphthalate, polyethylene terephthalate, polyethylene naphthalate, polyethylene terephthalate, polyethylene naphthalate, polyethylene terephthalate, polyethylene naphthalate, polyethylene terephthalate, polyethylene naphthalate, polypropylene, polyethylene terephthalate, polyethylene naphthalate, polypropylene, polyethylene terephthalate, at least one of polyethernitrile, polyurethane, polyphenylene ether, polyester, polysulfone, amorphous α -olefin copolymer, and derivatives thereof.

Further, the inorganic insulating material includes hafnium oxide (HfO)₂) Strontium titanate (SrTiO)₃) Tin oxide (SnO)₂) Cerium oxide (CeO)₂) Magnesium oxide (MgO), nickel oxide (NiO), calcium oxide (CaO), barium oxide (BaO), zinc oxide (ZnO), zirconium dioxide (ZrO)₂) Yttrium oxide (Y)₂O₃) Alumina (Al)₂O₃) Titanium dioxide (TiO)₂) Silicon dioxide (SiO)₂) Boehmite, magnesium hydroxide (Mg (OH)₂) Or aluminum hydroxide (Al (OH)₃) At least one of (1).

Referring to fig. 5, the spacer 30 includes a heating element 301 and an encapsulation layer 303 on a surface of the heating element 301, i.e., the spacer 30 may not include the insulating layer 302. In fig. 5, which shows the case that the encapsulating layer 303 completely covers the surface of the heating element 301, the encapsulating layer 303 may be only located at the end edge of the insulating layer 302 for encapsulation, i.e. the main surface portion of the heating element 301 is exposed and not covered by the encapsulating layer 303, as shown in fig. 6.

Further, the heating element 301 shown in fig. 5 and 6 may also comprise a patterned shape as shown in fig. 4, i.e. comprising a plurality of first portions 3011 arranged in parallel, adjacent two first portions 3011 being connected by a second portion 3012. Further, an insulator 304 is provided between adjacent first portions 3011. Likewise, the heating element 301 may not include the patterned shape, which may be a unitary piece of completely continuous conductive material.

In some embodiments, the thickness H of the separator 30 ranges from 2 μm to 1000 μm, preferably from 5 μm to 50 μm, and more preferably from 5 μm to 20 μm. In some embodiments, the interfacial adhesion force F between the separator 30 and the housing 10 satisfies: f is more than or equal to 10N/cm, preferably more than or equal to 15N/cm.

Referring to fig. 7, the present application further provides an electric device 200 including the electrochemical apparatus 100 as described above.

In some embodiments, the powered device 200 further comprises a switch. When the temperature is below T1 or above T2, the switch closes, allowing current to pass through the heating element 301.

Further, T1 was 5 ℃ and T2 was 50 ℃.

The present application will be described in further detail with reference to specific examples.

Example 1

Preparing a negative pole piece: mixing the negative active material graphite, the conductive carbon black (Super P) and the Styrene Butadiene Rubber (SBR) according to the weight ratio of 96:1.5:2.5, adding deionized water, preparing into slurry with the solid content of 0.7, and uniformly stirring. And uniformly coating the slurry on a copper foil of a negative current collector, and drying at 110 ℃. And after the steps are completed, finishing the single-side coating of the negative pole piece. These steps are then also performed on the back side of the pole piece in a completely uniform manner. And then, carrying out processes of cold pressing, cutting and the like to complete the preparation of the negative pole piece.

Preparing a positive pole piece: 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), blending to obtain slurry with the solid content of 0.75, and uniformly stirring. And uniformly coating the slurry on an aluminum foil of the positive current collector, and drying at 90 ℃. These steps are then also performed on the back side of the pole piece in a completely uniform manner. Then cold pressing and cuttingAnd finishing the preparation of the positive pole piece by the procedures.

Preparing electrolyte: 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) Dissolved and mixed uniformly to obtain an electrolyte solution with the concentration of lithium salt of 1.15M.

Preparation of electrode assembly: polyethylene (PE) with the thickness of 15 mu m is selected as an isolating film, the positive pole piece, the isolating film and the negative pole piece are sequentially stacked, and then the stacked pole pieces and the isolating film are wound into a winding type electrode assembly.

Preparing a clapboard: uniformly dispersing polypropylene (PP) into a dispersing agent N-methylpyrrolidone (NMP) to prepare a suspension of a packaging layer; respectively preparing packaging layers on two sides of the heating element by using a glue spreader (the material of the heating element is 302 stainless steel, the texture shown in figure 4 is prepared in advance, and an insulator is filled between the first parts); drying the dispersing agent NMP in the suspension of the packaging layer at 130 ℃; two tabs were welded to the outermost ends of the above 302 stainless steel as terminals to be introduced for connection to a heating circuit, the resistance R1 between the two terminals was 1.23 Ω, and a paper tape was pasted to complete the preparation of the separator, which was constructed as shown in fig. 5. The thickness of the spacer is 20 μm, where the heating element 302 stainless steel has a melting point (softening point) of 1440 ℃, the potting layer PP has a melting point (softening point) of 150 ℃, and the difference is 1290 ℃.

Assembling the lithium ion battery I: a case (aluminum plastic film, thickness of approximately 90 μm) formed by punching a pit was placed in the assembly jig 1 with the pit facing upward, the first electrode assembly was placed in the pit, and then a separator was placed over the first electrode assembly and pressed by applying an external force.

Assembling of the lithium ion battery II: and (3) placing the semi-finished product obtained in the step (I) in an assembly fixture 2, enabling the exposed surface of the partition plate to face upwards, placing the second electrode assembly above the partition plate, pressing, covering the pit surface of the other shell downwards above the second electrode assembly, and carrying out heat sealing on the periphery.

And (v) liquid injection packaging: and respectively and independently injecting liquid into the two cavities, and packaging the periphery of the liquid after injection, wherein the periphery of the partition plate is sealed in the seal. The two electrode assemblies are separated into two independent sealed cavities by the partition plates, and no ion exchange exists between the two electrode assemblies. All the tabs of the two electrode assemblies are led out of the shell for subsequent processing.

Ninthly, series connection: and connecting the positive electrode lug of the first electrode assembly and the negative electrode lug of the second electrode assembly together by welding (laser welding, ultrasonic welding or resistance welding) to realize series connection and conduction between the two electrode assemblies, and finishing the assembly of the lithium ion battery.

Example 2

The difference from example 1 is that: the material of the packaging layer is Polyethylene (PE), the melting point (softening point) of the packaging layer is 120 ℃, and the difference value between the melting point (softening point) of the packaging layer and the melting point (softening point) of the heating element is 1320 ℃.

Example 3

The difference from example 1 is that: the material of the packaging layer is polystyrene, the melting point (softening point) of the packaging layer is 240 ℃, and the difference between the melting point (softening point) of the packaging layer and the melting point (softening point) of the heating element is 1200 ℃.

Example 4

The difference from example 1 is that: the heating element is made of copper (Cu), the melting point (softening point) of the heating element is 1080 ℃, the melting point (softening point) of the packaging layer PP is 130 ℃, and the difference between the melting point (softening point) of the packaging layer PP and the melting point (softening point) of the heating element is 950 ℃.

Example 5

The difference from example 1 is that: the heating element is made of aluminum (Al), the melting point (softening point) of the heating element is 660 ℃, the melting point (softening point) of the packaging layer PP is 130 ℃, and the difference between the melting point (softening point) of the packaging layer PP and the melting point (softening point) of the heating element is 530 ℃.

Example 6

The difference from example 1 is that: the heating element is made of a carbon film, the melting point (softening point) of the heating element is 3500 ℃, the melting point (softening point) of the packaging layer PP is 150 ℃, and the difference between the melting point (softening point) of the packaging layer PP and the melting point (softening point) of the heating element is 3350 ℃.

Example 7

The difference from example 1 is that: the separator has a structure as shown in fig. 3, an insulating layer is further provided between the encapsulation layer and the insulator, the heating element is made of aluminum (Al), the melting point (softening point) of the heating element is 660 ℃, the melting point (softening point) of the encapsulation layer PP is 150 ℃, the difference between the melting point (softening point) of the encapsulation layer PP and the melting point (softening point) of the heating element is 510 ℃, and the thickness of the separator is 10 μm.

Example 8

The difference from example 7 is that: the thickness of the separator is 2 μm.

Example 9

The difference from example 7 is that: the resistance R1 between the two terminals of the heating element was made 31.22 Ω by changing the pitch of the first portion.

Example 10

The difference from example 7 is that: the resistance R1 between the two terminals of the heating element was made 7.43 Ω by changing the pitch of the first portion.

Example 11

The difference from example 7 is that: the resistance R1 between the two terminals of the heating element is made 0.2 Ω by changing the pitch of the first portion.

Example 12

The difference from example 7 is that: the heating element is not provided with grains, and the resistance R1 between two terminals of the heating element is 0.05 omega.

Comparative example 1

The difference from example 1 is that: the assembly process of the lithium ion battery comprises the following steps: and packaging an electrode assembly by using an aluminum plastic film, and carrying out liquid injection formation and side edge packaging to prepare the electrochemical device.

Comparative example 2

The difference from comparative example 1 is that: two lithium ion batteries were made in the manner of comparative example 1. The anode tab of one lithium ion battery and the cathode tab of the other lithium ion battery are welded together through a conduction piece

Comparative example 3

The difference from example 1 is that: no separator is included.

Comparative example 4

The difference from example 1 is that: a common single-layer PP (polypropylene) is directly used as a separator, the melting point is 165 ℃, and the thickness is 20 mu m. And a heating Ni sheet is embedded in the first electrode assembly.

And (3) interface adhesion testing: taking off the part of the sealing area from the lithium ion battery as a sample 1; cutting the sample 1 into a test strip with the width of 8mm, and ensuring that the whole sealing area is completely preserved by the test strip to obtain a sample 2; tearing the partition plates and the shell at two sides at an angle of 180 degrees by using a high-speed rail tensile machine so that the partition plates and the shell are separated from each other; the stable tensile force F (N) at the time of separation was recorded, and based on this, the interfacial adhesion force F (N/cm) between the separator and the case was calculated to be F/0.8.

1.5m drop test: disassembling the lithium ion battery after the 1.5m drop, and independently taking down the sealing area for later use; dripping the red liquid medicine into the sealing area, enabling the space dimension red liquid medicine to be above and the sealing area to be below, and standing for 12 hours; then, the seal area is damaged through an interface bonding force test, and the condition that the red liquid medicine permeates into the seal area is observed; if the depth of the red liquid medicine penetrating into the seal area exceeds 1/2 of the width of the seal area, the seal position is judged to be broken, otherwise, the seal position is judged to be not broken. And (5) taking 20 lithium ion batteries for testing, and determining the breakage ratio.

0.1C discharge energy Density test: the lithium ion battery is charged from 3.0V to 4.4V at a charging rate of 1C and then discharged to 3.0V at a discharging rate of 0.1C in an environment of 25 ℃, and the 0.1C discharging capacity is measured, and the 0.1C discharging energy density is 0.1C discharging capacity/lithium ion battery volume.

Cycle capacity retention rate test: the lithium ion battery is charged from 3.0V to 4.4V at a charging rate of 2C and then discharged to 3.0V at a discharging rate of 0.2C in an environment of 25 ℃, the discharging capacity at this time is determined as a first discharging capacity, the charging and discharging cycle is repeated for 50 times, and the discharging capacity at the 50 th discharging is determined, wherein the cycle capacity retention rate is the 50 th discharging capacity/the first discharging capacity.

3C charging temperature rise test: the maximum cell surface temperature was tested when a lithium ion cell was charged from 0% state of charge (SOC) to 100% SOC at a 3C charge rate in a 25 ℃ environment. The temperature rise in the 3C charging is-25 ℃ maximum of the surface of the battery.

No lithium analysis capability boundary test: the lithium ion battery is respectively placed in an environment of minus 10 ℃ and plus 25 ℃, when the environment is minus 10 ℃, the lithium ion battery with a heating element firstly heats the battery to 25 ℃ of the highest temperature point of the battery surface with 50W, the charging rate when lithium precipitation is started is determined, the lithium ion battery without the heating element does not have the heating step, and the lithium precipitation-free capacity boundary is the charging rate when lithium precipitation is started under the environment of minus 10 ℃ or the charging rate when lithium precipitation is started under the environment of minus 25 ℃.

And (3) heating temperature difference test: and (3) heating the lithium ion battery from minus 10 ℃ to 25 ℃ at the highest temperature point of the battery surface at the power of 50W, and testing the maximum temperature difference (DEG C) of the battery surface.

The parameter settings and test results of the above examples and comparative examples are shown in Table 1 and Table 2, respectively.

TABLE 1

TABLE 2

As can be seen from tables 1 and 2, the energy density of the lithium ion batteries of examples 1 to 12 is equivalent to that of the single lithium ion battery of comparative example 1, because the separators are used instead of the two-layer case; and the energy density is greatly improved compared with that of comparative example 2 (two lithium ion batteries are connected in series). From the results of comparative example 3, it is understood that the separators in examples 1 to 12 can effectively achieve the ion insulating function. Compared with the comparative example 4, the maximum temperature difference of the surfaces of the lithium ion batteries in the examples 1 to 12 is remarkably reduced, and the lithium precipitation-free capacity boundary is remarkably improved, so that the temperature equalization capacity of the batteries is remarkably improved, and compared with the comparative example 1, the 3C charging temperature rise is reduced, and the high-rate charge and discharge performance of the batteries is improved. In addition, the cycle capacity retention rate of the lithium ion batteries of examples 1 to 12 is superior to that of comparative example 4, and it can be seen that the interfacial contact degradation inside the lithium ion batteries is improved.

The application provides an electrochemistry device and consumer, with inside heating element imbeds the baffle, except can realizing the ion insulation function of baffle and guaranteeing the reliability of encapsulation, the heating element that simultaneously can also utilize the intermediate level realizes electrochemistry device's heating function, effectively improved among the prior art baffle mechanical strength, the not good problem of thermal stability, the energy density that internal heating mode leads to among the prior art has been improved simultaneously and has been reduced, the self-discharge problem is serious, there is reliability risk scheduling problem.

Claims

1. An electrochemical device comprising a separator and a plurality of electrode assemblies within a housing, wherein the separator comprises a heating element.

2. The electrochemical device according to claim 1, wherein the plurality of electrode assemblies are respectively disposed in a plurality of cavities separated by the separators within the case.

3. The electrochemical device of claim 1 further comprising a first terminal and a second terminal electrically connected to said heating element, said first terminal and said second terminal having a first resistance R1 therebetween satisfying: r1 is more than or equal to 5m omega.

4. The electrochemical device according to claim 3, wherein said electrode assembly comprises a first tab and a second tab of opposite polarity, and said first tab and said second tab in the same electrode assembly have an internal resistance R therebetween satisfying: R1/R is more than or equal to 0.05 and less than or equal to 5000.

5. The electrochemical device of claim 4 wherein at least one of said first tabs is electrically connected to said first terminal.

6. The electrochemical device of claim 1, wherein at least two of the electrode assemblies are connected in series.

7. The electrochemical device of claim 1, wherein said separator further comprises an insulating layer on at least one side of said heating element.

8. The electrochemical device of claim 7, wherein at least one of the following conditions is satisfied:

i) the heating element comprises a patterned shape;

ii) the material of the insulating layer includes at least one of polymer and inorganic insulating material;

iii) the separator further comprises an encapsulation layer on the surface of the insulating layer.

9. The electrochemical device of claim 8, wherein at least one of the following conditions is met:

a) the interfacial adhesion force F between the partition board and the shell meets the following requirements: f is more than or equal to 10N/cm;

b) the patterned shape comprises a plurality of first parts which are arranged in parallel, two adjacent first parts are connected through a second part, and the two adjacent first parts are arranged at intervals; an insulator is arranged between the adjacent first parts, and the material of the insulator comprises at least one of polymer and inorganic insulating material;

c) the packaging layer is made of at least one of polypropylene, anhydride modified polypropylene, polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate, ethylene-acrylic acid copolymer, ethylene-vinyl alcohol copolymer, polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, polyamide, polyester, amorphous alpha-olefin copolymer and derivatives of the above substances;

d) the polymer includes polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyetheretherketone, polyimide, polyamide, polyethylene glycol, polyamideimide, polycarbonate, cyclic polyolefin, polyphenylene sulfide, polyvinyl acetate, polytetrafluoroethylene, polymethylene naphthalene, polyvinylidene fluoride, polyethylene naphthalate, polypropylene carbonate, poly (vinylidene fluoride-hexafluoropropylene), poly (vinylidene fluoride-co-chlorotrifluoroethylene), silicone, vinylon, polypropylene, anhydride-modified polypropylene, polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate, ethylene-acrylic acid copolymer, ethylene-vinyl alcohol copolymer, polyvinyl chloride, polystyrene, polyethernitrile, polyurethane, polyphenylene oxide, polyester, polyethylene terephthalate, polyethylene naphthalate, polyetheretherketone, poly (ethylene carbonate), poly (vinylidene fluoride-co-hexafluoropropylene), poly (vinylidene fluoride-co-chlorotrifluoroethylene), poly (vinylon-co-vinylon), poly (ethylene-vinyl acetate), ethylene-ethyl acrylate), ethylene-acrylic acid copolymer, ethylene-vinyl alcohol copolymer, polyvinyl chloride, polystyrene, polyethernitrile, polyurethane, polyphenylene oxide, polyester, poly (butylene terephthalate), poly (ethylene naphthalate), poly (ethylene carbonate), poly (ethylene), poly (butylene terephthalate), poly (ethylene), poly (butylene terephthalate), poly (ethylene, poly (butylene terephthalate), poly (ethylene), poly, At least one of polysulfone, amorphous alpha-olefin copolymer and derivatives thereof;

e) the inorganic insulating material comprises at least one of hafnium oxide, strontium titanate, tin oxide, cerium oxide, magnesium oxide, nickel oxide, calcium oxide, barium oxide, zinc oxide, zirconium dioxide, yttrium oxide, aluminum oxide, titanium dioxide, silicon dioxide, boehmite, magnesium hydroxide or aluminum hydroxide;

f) the material of the heating element comprises at least one of carbon material or metal material;

g) the thickness H of the separator satisfies: h is more than or equal to 2 mu m.

10. The electrochemical device of claim 9, wherein the carbon material comprises at least one of a carbon felt, a carbon film, carbon black, acetylene black, fullerene, a conductive graphite film, or a graphene film; the metal material comprises at least one of nickel, titanium, copper, silver, gold, platinum, iron, cobalt, chromium, tungsten, molybdenum, aluminum, magnesium, potassium, sodium, calcium, strontium, barium, silicon, germanium, tin, lead, indium, zinc or stainless steel.

11. An electrical device comprising an electrochemical apparatus according to any one of claims 1 to 10.

12. The powered device of claim 11, wherein the powered device further comprises a switch; when the temperature is below T1 or above T2, the switch is closed, allowing current to pass through the heating element.

13. The consumer of claim 12, wherein T1 is 5 ℃ and T2 is 50 ℃.