CN114628630A - Electrochemical device and electronic device - Google Patents
Electrochemical device and electronic device Download PDFInfo
- Publication number
- CN114628630A CN114628630A CN202210276876.3A CN202210276876A CN114628630A CN 114628630 A CN114628630 A CN 114628630A CN 202210276876 A CN202210276876 A CN 202210276876A CN 114628630 A CN114628630 A CN 114628630A
- Authority
- CN
- China
- Prior art keywords
- negative electrode
- edge region
- active material
- material layer
- positive electrode
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M2010/4292—Aspects relating to capacity ratio of electrodes/electrolyte or anode/cathode
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Battery Electrode And Active Subsutance (AREA)
- Secondary Cells (AREA)
Abstract
The present application provides an electrochemical device and an electronic device. In some embodiments of the present application, an electrochemical device is provided, comprising: a positive electrode including a positive electrode current collector and a positive electrode active material layer on the positive electrode current collector; a negative electrode including a negative electrode current collector and a negative electrode active material layer on the negative electrode current collector, the negative electrode active material layer including in a first direction: the edge area is positioned on one side or two sides of the main body area, and the first direction is parallel to the width direction of the negative electrode current collector; the ratio of the capacity per unit area of the edge region to the capacity per unit area of the positive electrode active material layer is CB1，1.05≤CB1Less than or equal to 1.25. The application can improve the safety performance and prevent deformation.
Description
Technical Field
The present application relates to the field of electrochemical energy storage, in particular to electrochemical devices and electronic devices.
Background
With the development of electrochemical energy storage technology, higher and higher requirements are put on the safety performance of electrochemical devices (e.g., lithium ion batteries). Further improvements in electrochemical devices are desired because the electrochemical devices tend to precipitate lithium in the edge region of the negative electrode during charging, leading to safety hazards.
Disclosure of Invention
In some embodiments of the present application, an electrochemical device is providedThe device, it includes: a positive electrode including a positive electrode current collector and a positive electrode active material layer on the positive electrode current collector; an anode including an anode current collector and an anode active material layer on the anode current collector, the anode active material layer including in a first direction: the edge area is positioned on one side or two sides of the main body area, and the first direction is parallel to the width direction of the negative electrode current collector; the ratio of the capacity per unit area of the edge region to the capacity per unit area of the positive electrode active material layer is CB1，1.05≤CB1≤1.25。
In some embodiments of the present application, the ratio of the capacity per unit area of the body region to the capacity per unit area of the positive electrode active material layer is CB2，1.03≤CB2≤1.045。
In some embodiments of the present application, the weight per unit area of the edge region and the weight per unit area of the body region are the same, and/or the thickness of the edge region and the thickness of the body region are the same.
In some embodiments of the present application, the length of the edge region in the first direction is not less than 2 mm; and/or the length of the edge region in the first direction is no more than 10% of the length of the negative electrode in the first direction.
In some embodiments of the present application, the anode active material layer includes an anode material, and a gram capacity of the anode material of the body region is smaller than a gram capacity of the anode material of the edge region.
In some embodiments of the present application, the anode material of the body region comprises: graphite; and/or the negative electrode material of the edge region comprises at least one of graphite, silicon, a silicon-based material, a silicon-carbon composite, or a metal.
In some embodiments of the present application, the negative electrode material of the edge region includes silicon, and the mass ratio of the silicon in the negative electrode material of the edge region is 0.1% to 5% of the total mass of the negative electrode material.
In some embodiments of the present application, the negative electrode active material layer includes a conductive agent including: at least one of carbon black, acetylene black, ketjen black, carbon fiber, carbon nanotube, or metal powder; and/or the negative electrode active material layer comprises a binder, and the binder comprises at least one of polyvinyl alcohol, sodium carboxymethyl cellulose, styrene-butadiene rubber, polytetrafluoroethylene or polyethylene oxide.
In some embodiments of the present application, the negative electrode active material layer is disposed on the negative electrode current collector by gravure printing plus coating.
Embodiments of the present application also provide an electronic device including the electrochemical device described above.
In some embodiments of the present application, an electrochemical device is provided, comprising: a positive electrode including a positive electrode current collector and a positive electrode active material layer on the positive electrode current collector; a negative electrode including a negative electrode current collector and a negative electrode active material layer on the negative electrode current collector, the negative electrode active material layer including in a first direction: the edge area is positioned on one side or two sides of the main body area, and the first direction is parallel to the width direction of the negative electrode current collector; the ratio of the capacity per unit area of the edge region to the capacity per unit area of the positive electrode active material layer is CB1CB1 is more than or equal to 1.05 and less than or equal to 1.25. The lithium ion battery can prevent lithium precipitation in the edge area, improve safety performance and prevent deformation.
Drawings
FIG. 1 illustrates a front view of a negative electrode of an electrochemical device in some embodiments of the present application
Fig. 2 illustrates a top view of a negative electrode of an electrochemical device according to some embodiments of the present application.
Fig. 3 illustrates a cross-sectional view of an edge region of a negative electrode of an electrochemical device in some embodiments of the present application.
Fig. 4 illustrates a cross-sectional view of a bulk region of a negative electrode of an electrochemical device according to some embodiments of the present application.
Detailed Description
The following examples are presented to enable those skilled in the art to more fully understand the present application and are not intended to limit the present application in any way.
For the design of an electrochemical device (for example, a lithium ion battery), it is necessary to reserve a sufficient space for lithium, which is extracted from a positive electrode plate, to be completely embedded into a negative electrode material in a negative electrode plate, so that the length and/or width edge of the negative electrode plate usually exceeds the corresponding length and/or width of the positive electrode plate, i.e., an edge region is formed.
Taking a lithium ion battery as an example, an edge region corresponding to a negative electrode of the lithium ion battery generally comprises a non-lithium-intercalation region, a transition region and a lithium-intercalation region from the edge to the inside, in the discharging process of the battery, lithium ions are distributed at the edge of the negative electrode and are sequentially reduced from the lithium-intercalation region and the transition region to the non-lithium-intercalation region, and the lithium ions in a negative active material can be freely diffused from high concentration to low concentration until reaching a lithium ion concentration equilibrium position in the edge region, as known from a free diffusion law; during discharging, lithium ions can be extracted from the negative electrode embedded with lithium and then are embedded into the positive electrode through the electrolyte and the isolating film; however, since the edge region of the negative electrode does not correspond to the positive electrode, the lithium removal reaction does not occur directly due to the absence of a driving force during the discharge process, the lithium ion concentration in the lithium insertion region at the edge of the negative electrode decreases with the increase of the discharge time, and the lithium ion concentration in the lithium non-insertion region is high. Due to the concentration diffusion, lithium ions are enriched in the edge region, and lithium deposition easily occurs in the edge region.
For a narrow and long structure, more electrolyte is stored at the head and the tail of an electrode assembly of an electrochemical device, so that the head and the tail are soaked in the electrolyte for a long time, the bonding force between the positive and negative electrode plates and the isolating membrane is weakened when the electrode plates at the head and the tail are soaked in the electrolyte for a long time, the gap between the positive and negative electrode plates is increased, the electron transmission distance is increased, the impedance is increased after the diffusion distance of lithium ions at the positive electrode in a liquid phase is increased, and the lithium ions at the edge area are difficult to embed and extract. In order to improve the lithium precipitation in the edge region, the kinetics of the edge region can be improved on the one hand, and the internal resistance increase of the pole piece in the cycle process of the edge region can be reduced on the other hand. The larger the charge state is, the faster the electrode assembly ages, and the larger the internal resistance increases, the easier lithium precipitation is; the larger the charging current density is, the more easily lithium is separated out; the lower the use temperature, the more negative the potential of the negative electrode becomes, and the more easily lithium deposition side reactions occur on the surface of the negative electrode.
In some embodiments of the present application, an electrochemical device is provided that improves the problem of lithium evolution by properly designing the state of charge. In some embodiments of the present application, an electrochemical device comprises: the positive electrode comprises a positive electrode current collector and a positive electrode active substance layer positioned on the positive electrode current collector, the positive electrode current collector can use copper foil or aluminum foil, and the positive electrode active substance layer is positioned on one side or two sides of the positive electrode current collector; referring to fig. 1, the negative electrode includes a negative current collector 10 and a negative active material layer 1 on the negative current collector 10, the negative current collector 10 may use a copper foil or an aluminum foil, the negative active material layer 1 may be on one side or both sides of the negative current collector 10, and the positive electrode and the negative electrode may be disposed opposite to each other, and referring to fig. 2, the negative active material layer 1 includes in a first direction: an edge region 11 and a body region 12, the edge region 11 being located at one side or both sides of the body region 12, the first direction being parallel to a width direction of the negative electrode current collector 10; the ratio of the capacity per unit area of the edge region to the capacity per unit area of the positive electrode active material layer is CB1，1.05≤CB1≤1.25。
In some embodiments of the present application, the capacity per unit area of the edge region is greater than the capacity per unit area of the positive electrode active material layer, so that the edge region can ensure accommodation of lithium ions released from the positive electrode, and prevent lithium deposition caused by insufficient position of the negative electrode to receive lithium ions, and at the same time, CB1It is required to be more than 1.05, besides ensuring that the edge region of the negative electrode can contain lithium ions released by the positive electrode, the capacity of the negative electrode is sufficiently large in the edge region, so that the state of charge of the edge region of the negative electrode can be limited to a lower level, compared with the negative electrode in a fully-embedded state, the potential is higher, so that the potential of the edge region of the negative electrode is far away from the lithium precipitation potential, on the other hand, the aging rate of the electrochemical device can be reduced by controlling the edge region to be in a lower state of charge, so that the impedance increase rate of the electrochemical device is slowed down,the dynamic performance of the negative electrode is maintained at a better level, so that lithium insertion is easier, and lithium separation is further prevented. Meanwhile, the control CB in the present embodiment1Not more than 1.25, thereby avoiding the problems of cost increase caused by excessive surplus capacity and increase of lithium ion transmission path, and more importantly, experiments show that when CB is in use>1.25, the electrochemical device suffers from pole piece deformation after full charge.
In some embodiments of the present application, the ratio of the capacity per unit area of the body region 12 to the capacity per unit area of the positive electrode active material layer is CB2，1.03≤CB2Less than or equal to 1.045. In some embodiments of the present application, 1.03 ≦ CB2That is, the capacity per unit area of the body region 11 is larger than that of the positive electrode active material layer, thus ensuring that lithium discharged from the positive electrode can be sufficiently inserted into the negative electrode, and at the same time, CB21.045 ≦ that is, the capacity of the main body region 11 per unit area is smaller than the capacity of the edge region 11 per unit area, because for the negative electrode, the edge region is in contact with the electrolyte, and therefore the main body region has a strong adhesion compared with the edge region, and the edge region has a poor adhesion, and on the other hand, the edge electrolyte soaking causes a poor cohesion, so that the main body region is more easily embedded with lithium.
In some embodiments of the present application, the weight per unit area of the edge region is the same as the weight per unit area of the body region, and in some embodiments, the thickness of the edge region is the same as the thickness of the body region. In some embodiments of the present application, the weight and thickness of the edge region and the body region may be the same, thereby avoiding non-uniformity of the negative electrode, and avoiding problems of wrinkling and curling during lamination or winding due to non-uniform weight or non-uniform thickness.
In some embodiments of the present application, the length of the edge area 11 in the first direction is not less than 2 mm. In some embodiments, the edge region 11 may be or include an edge region, and the length of the edge region 11 in the first direction may be the width of the edge region, and the width thereof is not less than 2mm so as to ensure a sufficient width of the edge region 11, so that the negative electrode has a sufficient margin when the positive electrode and the negative electrode are laminated or wound, and if the edge region is too narrow, it may be difficult to control the negative electrode active material layer over the positive electrode active material layer when the positive electrode and the negative electrode are laminated together, which may cause processing difficulty, and the improvement effect on lithium deposition may be reduced.
In some embodiments, the length of the edge region 11 in the first direction is no greater than 10% of the length of the negative electrode in the first direction. In some embodiments, the length of the edge region 11 in the direction may not be too large, which may significantly increase the manufacturing cost if the length of the edge region 11 in the first direction is too large.
In some embodiments of the present application, the anode active material layer includes an anode material, and a gram capacity of the anode material of the body region is smaller than a gram capacity of the anode material of the edge region. The cathode material with a large gram capacity is adopted in the edge area, so that the gram capacity of the edge area is improved, and lithium precipitation is inhibited. In some embodiments of the present application, the anode material of the body region comprises: graphite; in some embodiments, the negative electrode material of the edge region includes at least one of graphite, silicon, a silicon-based material, a silicon-carbon composite, or a metal, and in some embodiments, the gram capacity of the graphite used in the edge region may be higher than the gram capacity of the graphite used in the body region. In some embodiments, fig. 3 schematically shows a cross-sectional view of an edge region, and a negative active material layer on the negative current collector 10 of the edge region may include the conductive layer 13 and the mixed negative material 15, and fig. 4 schematically shows a cross-sectional view of a body region, and it can be seen that the negative active material layer on the negative current collector 10 of the body region may include the conductive layer 13 and the graphite 14.
In some embodiments of the present application, the anode material of the edge region includes silicon, and a mass ratio of silicon in the anode material of the edge region is 0.1% to 5% of a total mass ratio of the anode material. In some embodiments, a mixture of silicon and graphite or a mixture of silicon and other negative electrode materials is used in the edge region, and the silicon generates a large volume change during lithium deintercalation, so that the mass content needs to be controlled to avoid damage to the negative electrode active material layer caused by an excessive volume change.
In some embodiments of the present application, the negative electrode active material layer includes a conductive agent including: at least one of carbon black, acetylene black, ketjen black, carbon fiber, carbon nanotube, or metal powder; in some embodiments, the negative electrode active material layer includes a binder including at least one of polyvinyl alcohol, sodium carboxymethyl cellulose, styrene-butadiene rubber, polytetrafluoroethylene, or polyethylene oxide.
In some embodiments of the present application, the negative electrode active material layer is disposed on the negative electrode current collector by gravure printing plus coating. In some embodiments, gravure printing is used to increase adhesion between the negative electrode current collector and the negative electrode active material layer, increasing conductivity.
In some embodiments of the present application, the composition and coating weight of the positive electrode active material layer corresponding to the main region and the positive electrode active material layer corresponding to the edge region are the same, that is, the present application may be such that only the negative electrode active material layer is modified without modifying the positive electrode, thereby suppressing lithium deposition.
In some embodiments, the positive electrode active material layer may include a positive electrode material, a conductive agent, and a binder. In some embodiments, the positive electrode material may include at least one of lithium cobaltate, lithium iron phosphate, lithium aluminate, lithium manganate, or lithium nickel cobalt manganate. In some embodiments, the conductive agent of the positive electrode sheet may include at least one of carbon black, lamellar graphite, graphene, or carbon nanotubes. In some embodiments, the binder in the positive electrode sheet may include at least one of polyvinylidene fluoride, a copolymer of vinylidene fluoride-hexafluoropropylene, a styrene-acrylate copolymer, a styrene-butadiene copolymer, a polyamide, polyacrylonitrile, a polyacrylate, a polyacrylic acid, a polyacrylate, sodium carboxymethyl cellulose, polyvinyl acetate, polyvinylpyrrolidone, a polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, or polyhexafluoropropylene. In some embodiments, the mass ratio of the positive electrode material, the conductive agent, and the binder in the positive electrode active material layer 102 is (80-99): (0.1-10): (0.1-10), but this is merely an example and any other suitable mass ratio may be employed.
In some embodiments, the electrochemical device comprises a separator between the positive electrode and the negative electrode, the separator comprising at least one of polyethylene, polypropylene, polyvinylidene fluoride, polyethylene terephthalate, polyimide, or aramid. For example, the polyethylene includes at least one selected from high density polyethylene, low density polyethylene, or ultra high molecular weight polyethylene. Particularly polyethylene and polypropylene, which have a good effect on preventing short circuits and can improve the stability of the battery through a shutdown effect. In some embodiments, the thickness of the separation film 11 is in the range of about 3 μm to 20 μm.
In some embodiments, the surface of the separator may further include a porous layer disposed on at least one surface of the separator, the porous layer including inorganic particles selected from alumina (Al) and a binder2O3) Silicon oxide (SiO)2) Magnesium oxide (MgO), titanium oxide (TiO)2) Hafnium oxide (HfO)2) Tin oxide (SnO)2) Cerium oxide (CeO)2) Nickel oxide (NiO), zinc oxide (ZnO), calcium oxide (CaO), zirconium oxide (ZrO)2) Yttrium oxide (Y)2O3) At least one of silicon carbide (SiC), boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, or barium sulfate. In some embodiments, the pores of the separator film have a diameter in the range of about 0.01 μm to 1 μm. The binder of the porous layer is at least one selected from polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethylcellulose, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene and polyhexafluoropropylene. The porous layer on the surface of the isolating membrane can improve the heat resistance, the oxidation resistance and the electrolyte infiltration performance of the isolating membrane and enhance the adhesion between the isolating membrane and the pole piece.
In some embodiments, the electrochemical device comprises a lithium ion battery, but the application is not so limited. In some embodiments, the electrochemical device further comprises an electrolyte comprising at least one of fluoroether, fluoroether carbonate, or ether nitrile. In some embodiments, the electrolyte further includes a lithium salt including lithium bis (fluorosulfonyl) imide and lithium hexafluorophosphate, the concentration of the lithium salt is 1 to 2mol/L, and the mass ratio of lithium bis (fluorosulfonyl) imide to lithium hexafluorophosphate is 0.06 to 5. In some embodiments, the electrolyte may further include a non-aqueous solvent. The non-aqueous solvent may be a carbonate compound, a carboxylate compound, an ether compound, other organic solvent, or a combination thereof.
The carbonate compound may be a chain carbonate compound, a cyclic carbonate compound, a fluoro carbonate compound, or a combination thereof.
Examples of the chain carbonate compound are diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), Methyl Propyl Carbonate (MPC), Ethyl Propyl Carbonate (EPC), Methyl Ethyl Carbonate (MEC), and combinations thereof. Examples of the cyclic carbonate compound are Ethylene Carbonate (EC), Propylene Carbonate (PC), Butylene Carbonate (BC), Vinyl Ethylene Carbonate (VEC), or a combination thereof. Examples of the fluoro carbonate compound are fluoroethylene carbonate (FEC), 1, 2-difluoroethylene carbonate, 1, 2-trifluoroethylene carbonate, 1,2, 2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1, 2-difluoro-1-methylethylene carbonate, 1, 2-trifluoro-2-methylethylene carbonate, trifluoromethylethylene carbonate, or a combination thereof.
Examples of carboxylate compounds are methyl acetate, ethyl acetate, n-propyl acetate, t-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, gamma-butyrolactone, decalactone, valerolactone, mevalonic lactone, caprolactone, methyl formate, or combinations thereof.
Examples of the ether compound are dibutyl ether, tetraglyme, diglyme, 1, 2-dimethoxyethane, 1, 2-diethoxyethane, ethoxymethoxyethane, 2-methyltetrahydrofuran, tetrahydrofuran, or a combination thereof.
Examples of other organic solvents are dimethylsulfoxide, 1, 2-dioxolane, sulfolane, methyl sulfolane, 1, 3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, formamide, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, trioctyl phosphate, and phosphate esters or combinations thereof.
Embodiments of the present application also provide an electronic device including the electrochemical device described above. The electronic device of the embodiment of the present application is not particularly limited, and may be any electronic device known in the art. In some embodiments, the electronic device may include, but is not limited to, a notebook computer, a pen-input computer, a mobile computer, an electronic book player, a portable phone, a portable facsimile machine, a portable copier, a portable printer, a headphone, a video recorder, a liquid crystal television, a handheld cleaner, a portable CD player, a mini-disc, a transceiver, an electronic notebook, a calculator, a memory card, a portable recorder, a radio, a backup power source, an electric motor, an automobile, a motorcycle, a power-assisted bicycle, a bicycle, an unmanned aerial vehicle, a lighting fixture, a toy, a game machine, a clock, an electric tool, a flashlight, a camera, a large household battery, a lithium ion capacitor, and the like.
In the following, some specific examples and comparative examples are listed to better illustrate the present application, wherein a lithium ion battery is taken as an example.
Example 1
Preparation of a negative electrode: the current collector adopts copper foil, the edge area adopts a mixture of graphite and silicon as a negative electrode material, and the conductive agent material carbon black and the binder adopt styrene butadiene rubber and carboxymethyl cellulose. Mixing a mixed negative electrode material, a conductive agent and a binder according to the mass percentage of 98: 1: 1 mixing and dispersing in deionized water to form slurry of the edge area. Graphite is used as a negative electrode material in the main body area, and styrene butadiene rubber and carboxymethyl cellulose are used as conductive agent materials of carbon black and a binder. And (2) mixing the negative electrode material, the conductive agent and the binder according to the mass percentage of 98: 1: 1 mixing and dispersing in deionized water to form a slurry of the main body area. Coating the slurry of the main body area on the copper foil to form a main body area, coating the slurry of the edge area on one side of the main body area to form an edge area, keeping the coating weight of the edge area consistent with that of the main body area in order to ensure that the compacted density is consistent, drying the coated edge area by a vacuum oven, and preparing the negative electrode with the consistent thickness and compacted density of the edge area and the main body area through three times of cold pressing and strip division.
Preparation of the positive electrode: mixing the positive electrode materials of lithium cobaltate, Carbon Nano Tubes (CNT), Super P and polyvinylidene fluoride (PVDF) according to the mass percentage content ratio of 96.2: 0.5: and (3) fully stirring and uniformly mixing in an N-methyl pyrrolidone solvent system, and coating on an aluminum foil to obtain a positive active material layer. And drying and cold pressing to obtain the anode.
Preparing an isolating membrane: stirring polyacrylate to form uniform slurry, coating the slurry on the two side surfaces of the porous base material (polyethylene), and drying to form the isolating membrane.
Preparing an electrolyte: under the environment that the water content is less than 10ppm, lithium hexafluorophosphate and a nonaqueous organic solvent (ethylene carbonate (EC), diethyl carbonate (DEC), Propylene Carbonate (PC), Propyl Propionate (PP), Vinylene Carbonate (VC), wherein the mass percentage ratio of lithium hexafluorophosphate to the Vinylene Carbonate (VC) is 8: 92 was formulated to form an electrolyte having a lithium salt concentration of 1 mol/L.
Preparing a lithium ion battery: and sequentially stacking the positive electrode, the isolating film and the negative electrode in sequence, so that the isolating film is positioned between the positive electrode piece and the negative electrode piece to play an isolating role, and winding to obtain the electrode assembly. And (3) placing the electrode assembly in an outer packaging aluminum-plastic film, dehydrating at 80 ℃, injecting the electrolyte, packaging, and carrying out technological processes such as formation, degassing, shaping and the like to obtain the lithium ion battery.
Each example and comparative example are different only in the negative electrode, and the specific differences are shown in the following table.
The test method of the present application is described below.
And (3) lithium precipitation of a negative electrode plate: charging the lithium ion battery to 4.3V by constant current of 1C multiplying power at 25 ℃, then charging to 4.5V by constant current of 0.5C multiplying power, finally charging to 0.05C by constant voltage of 4.5V, standing for 2min, then discharging to 3.0V by constant current of 1C, standing for 2min, taking the constant current as a cycle, repeating 800 cycles, and then disassembling lithiumThe ion battery obtains an electrode assembly, the electrode assembly is spread out, if any position of the edge area of the negative electrode is found to be larger than 2mm2The lithium is analyzed in the area (2), the lithium is analyzed at the edge, the thickness of the battery can be monitored in the testing process, and if the battery is abnormal, the battery can be disassembled to determine whether the lithium is analyzed in the edge area.
Expansion in the circulating process: the method is characterized in that important parameters of internal structure change in the circulation process of the reaction battery are that the abnormal interface, such as purple spots, black spots, lithium precipitation and the like, occurs in the circulation process of the battery, the circulation expansion rate is the thickness/initial thickness increased in the circulation process in the circulation test process of the lithium precipitation of the negative electrode plate, and the interface problem is generally confirmed by disassembling if the abnormal expansion in the circulation process occurs.
TABLE 1
The preparation parameters and performance test results of examples 1 to 7 and comparative example 1 are shown in the above table, in comparative example 1, graphite is used for both the edge region and the bulk region, and graphite and silicon are used as the mixed material, and in different examples, CB is controlled by controlling the content of silicon in the mixed material1。
As can be seen from Table 1, CB of comparative example 11CB of example 7, less than 1.051CB of greater than 1.25, examples 1 to 61The content of CB1 is more than or equal to 1.05 and less than or equal to 1.25. It can be seen that comparative example 1 has a high cycle expansion ratio and severe edge region lithium precipitation occurs and the battery deforms when the CB is improved1After that, no edge region lithium deposition occurred in the battery, and it can be seen that the control CB was passed1When the concentration is more than 1.05, the problem of lithium deposition in the edge region can be solved. As can be seen from examples 1 to 7, when CB1When the amount is within the range defined in the present application, the cyclic expansion ratio is small, no lithium deposition occurs in the edge region and the battery is not deformed, while when CB is used1When it exceeds 1.25, the cycle expansion ratio increases and deformation of the battery occurs, and it can be seen that, when CB is present1If the size is too large, the performance of the entire battery is adversely affected.
TABLE 2
Preparation parameters and performance test results of examples 2,8 to 9 As shown in the above table, the mixed materials were graphite and silicon, and in various examples, CB was controlled by controlling the content of silicon in the mixed materials1Control of CB by control of the type of graphite used in the main body region2。
As can be seen from Table 2, for examples 2,8 and 9, it satisfied 1.03. ltoreq. CB2≦ 1.045, its cyclic expansion is small and no lithium deposition occurs and there is no deformation, while in example 10, its gram capacity per unit area of the body area is too low, resulting in CB2Too small, less than 1.03, results in insufficient capacity of the host region to accommodate lithium ions, resulting in lithium precipitation, resulting in battery deformation, and an increase in cycle expansion rate.
TABLE 3
Preparation parameters and performance test results of examples 2,8, 10 to 11 As shown in the above table, the mixed materials were graphite and silicon, and in various examples, CB was controlled by controlling the content of silicon in the mixed materials1Control of CB by control of the type of graphite used in the main body region2。
As can be seen from table 3, while the negative electrode width was constant, the effect of changing the widths of the edge region and the main region on the battery was observed, and as can be seen from table 3, no edge region lithium deposition occurred in any of the above examples, and the battery was not deformed, and the cycle expansion rate was small, and it was seen that, in the case where the width of the edge region was not more than 10% of the negative electrode width, the safety performance and cycle performance of the battery could be ensured.
The above description is only a preferred embodiment of the application and is illustrative of the principles of the technology employed. It will be appreciated by those skilled in the art that the scope of the disclosure herein is not limited to the particular combination of features described above, but also encompasses other combinations of features described above or equivalents thereof. For example, the above features and the technical features having similar functions disclosed in the present application are mutually replaced to form the technical solution.
Claims (10)
1. An electrochemical device, comprising:
a positive electrode including a positive electrode current collector and a positive electrode active material layer on the positive electrode current collector;
an anode including an anode current collector and an anode active material layer on the anode current collector, the anode active material layer including in a first direction: an edge region and a body region, the edge region being located at one or both sides of the body region, the first direction being parallel to a width direction of the negative electrode current collector;
the ratio of the capacity per unit area of the edge region to the capacity per unit area of the positive electrode active material layer is CB1，1.05≤CB1≤1.25。
2. The electrochemical device according to claim 1, wherein a ratio of a capacity per unit area of the main region to a capacity per unit area of the positive electrode active material layer is CB2，1.03≤CB2≤1.045。
3. The electrochemical device according to claim 1,
the weight per unit area of the edge region is the same as the weight per unit area of the body region, and/or the thickness of the edge region is the same as the thickness of the body region.
4. The electrochemical device according to claim 1,
a length of the edge region in the first direction is not less than 2 mm; and/or the presence of a gas in the gas,
the length of the edge region in the first direction is not more than 10% of the length of the negative electrode in the first direction.
5. The electrochemical device according to claim 1, wherein the anode active material layer includes an anode material, and a gram capacity of the anode material of the main region is smaller than a gram capacity of the anode material of the edge region.
6. The electrochemical device according to claim 1,
the anode material of the body region includes: graphite;
and/or the negative electrode material of the edge region comprises at least one of graphite, silicon, a silicon-based material, a silicon-carbon composite or a metal.
7. The electrochemical device according to claim 5, wherein the negative electrode material of the edge region includes silicon, and a mass of silicon in the negative electrode material of the edge region accounts for 0.1 to 5% of a total mass ratio of the negative electrode material.
8. The electrochemical device according to claim 1, wherein the anode active material layer includes a conductive agent including: at least one of carbon black, acetylene black, ketjen black, carbon fiber, carbon nanotube, or metal powder; and/or the presence of a gas in the gas,
the negative electrode active material layer comprises a binder, and the binder comprises at least one of polyvinyl alcohol, sodium carboxymethyl cellulose, styrene-butadiene rubber polytetrafluoroethylene or polyethylene oxide.
9. The electrochemical device according to claim 1,
the negative electrode active material layer is arranged on the negative electrode current collector in a gravure printing and coating mode.
10. An electronic device comprising the electrochemical device according to any one of claims 1 to 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210276876.3A CN114628630A (en) | 2022-03-21 | 2022-03-21 | Electrochemical device and electronic device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210276876.3A CN114628630A (en) | 2022-03-21 | 2022-03-21 | Electrochemical device and electronic device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN114628630A true CN114628630A (en) | 2022-06-14 |
Family
ID=81904433
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210276876.3A Pending CN114628630A (en) | 2022-03-21 | 2022-03-21 | Electrochemical device and electronic device |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114628630A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115172661A (en) * | 2022-08-31 | 2022-10-11 | 江苏时代新能源科技有限公司 | Pole piece, electrode component, battery monomer, battery and power consumption device |
| CN116454415A (en) * | 2023-06-20 | 2023-07-18 | 深圳海辰储能控制技术有限公司 | Electrode assembly, battery and electric equipment |
| CN116759535A (en) * | 2023-08-22 | 2023-09-15 | 宁德新能源科技有限公司 | Electrochemical device and electronic apparatus |
| CN116825957A (en) * | 2023-08-28 | 2023-09-29 | 深圳市德兰明海新能源股份有限公司 | Secondary battery, preparation method thereof and electricity utilization device |
| CN117154001A (en) * | 2023-10-27 | 2023-12-01 | 中创新航科技集团股份有限公司 | Cylindrical battery |
-
2022
- 2022-03-21 CN CN202210276876.3A patent/CN114628630A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115172661A (en) * | 2022-08-31 | 2022-10-11 | 江苏时代新能源科技有限公司 | Pole piece, electrode component, battery monomer, battery and power consumption device |
| CN116454415A (en) * | 2023-06-20 | 2023-07-18 | 深圳海辰储能控制技术有限公司 | Electrode assembly, battery and electric equipment |
| CN116759535A (en) * | 2023-08-22 | 2023-09-15 | 宁德新能源科技有限公司 | Electrochemical device and electronic apparatus |
| CN116759535B (en) * | 2023-08-22 | 2024-01-05 | 宁德新能源科技有限公司 | Electrochemical device and electronic apparatus |
| CN116825957A (en) * | 2023-08-28 | 2023-09-29 | 深圳市德兰明海新能源股份有限公司 | Secondary battery, preparation method thereof and electricity utilization device |
| CN117154001A (en) * | 2023-10-27 | 2023-12-01 | 中创新航科技集团股份有限公司 | Cylindrical battery |
| CN117154001B (en) * | 2023-10-27 | 2024-02-20 | 中创新航科技集团股份有限公司 | Cylindrical battery |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN113394375B (en) | Electrochemical device and electronic device | |
| CN114628630A (en) | Electrochemical device and electronic device | |
| CN113097431B (en) | Electrochemical device and electronic device | |
| CN112687838B (en) | Electrochemical device, method for manufacturing the same, and electronic device | |
| CN113066961B (en) | Negative electrode sheet, electrochemical device, and electronic device | |
| US20240014390A1 (en) | Electrochemical Apparatus and Electronic Apparatus | |
| CN113366673A (en) | Electrochemical device and electronic device | |
| WO2023160182A1 (en) | Electrochemical device and electronic device | |
| CN113078288A (en) | Electrochemical device and electronic device | |
| CN113421999B (en) | Electrochemical device and electronic device | |
| CN113078293B (en) | Electrochemical device and electronic device | |
| CN114497557A (en) | Electrochemical device and electronic device | |
| CN114914396B (en) | Electrochemical device and electronic device | |
| CN116314608A (en) | Electrochemical device and electronic device | |
| CN114497498B (en) | Electrochemical device and electronic device | |
| CN113078287B (en) | Electrochemical device and electronic device | |
| CN213878153U (en) | Pole piece, electrochemical device and electronic device | |
| CN112542617B (en) | Electrochemical device and electronic device | |
| CN116097472A (en) | Electrochemical device, electronic device and method for preparing negative electrode plate | |
| CN115398667A (en) | Electrode, method of manufacturing the same, electrochemical device, and electronic device | |
| CN113363417A (en) | Electrochemical device and electronic device | |
| CN114122312A (en) | Pole piece, electrochemical device and electronic device | |
| CN112687942B (en) | Electrochemical device, method of manufacturing the same, and electronic device | |
| CN114649499B (en) | Electrochemical device and electronic device | |
| EP4266398A1 (en) | Electrochemical device and electronic device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |