CN113451586A - Electrode plate of secondary battery, secondary battery and preparation method of secondary battery - Google Patents
Electrode plate of secondary battery, secondary battery and preparation method of secondary battery Download PDFInfo
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- 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
- H01M4/64—Carriers or collectors
- H01M4/70—Carriers or collectors characterised by shape or form
- H01M4/80—Porous plates, e.g. sintered carriers
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- 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
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- 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
- H01M10/058—Construction or manufacture
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- 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
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- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract
The invention discloses an electrode plate of a secondary battery, the secondary battery and a preparation method thereof, wherein the electrode plate comprises a positive plate and/or a negative plate, the positive plate comprises a positive current collector and a positive active substance layer; the negative plate comprises a negative current collector; wherein the positive electrode current collector and/or the negative electrode current collector are in a porous structure. The secondary battery includes the electrode sheet and an electrolyte. The secondary battery adopts the current collector of the positive electrode and/or the negative electrode with a porous structure, so that the contact area of the active substance and the current collector can be effectively increased, the contact acting force of the active substance and the current collector is enhanced, and the active substance is not easy to fall off on the surface of the current collector; while improving thermal conduction efficiency and electronic conduction path, and thereby improving the power characteristics and cycle life of the battery.
Description
Technical Field
The invention belongs to the technical field of chemical power sources or energy storage batteries, and particularly relates to an electrode plate of a secondary battery, the secondary battery and a preparation method of the secondary battery.
Background
Secondary batteries (such as lithium ion batteries) are widely used in today's society, such as mobile phones, notebook computers, tablet computers, electric vehicles, electric bicycles, electric buses, industrial and household energy storage, aerospace, and the like. Different application scenes have different requirements on various indexes of the battery, but generally speaking, the battery is expected to have the indexes of specific energy, energy density, quick charge, power density, low-temperature discharge, high-temperature storage, high-temperature cycle, floating charge, intermittent cycle, pulse discharge, low cost, environmental protection and the like on the premise of ensuring the safety.
The existing lithium ion battery monomer mainly comprises a positive plate, an electrolyte, an isolating membrane, a negative plate and a packaging material. The positive plate is composed of an aluminum foil current collector with a compact structure and a lithium-containing active substance layer coated on the current collector, the electrolyte is formed by dissolving lithium salt (such as lithium hexafluorophosphate) in an organic solvent (ethylene carbonate, ethyl methyl carbonate, propylene carbonate and the like), the isolating film is a polyolefin porous film, and the negative plate is composed of a copper foil current collector with a compact structure and a lithium-free active substance layer coated on the current collector.
The selection design of the battery structure or the components can not effectively improve the requirements of various performance indexes required in the practical application of the battery. The method mainly comprises the following points: (1) the organic liquid electrolyte has flammability, and is easy to have safety problem under the condition of high temperature and high charge state when matched with a high nickel-based positive electrode material to manufacture a rechargeable secondary lithium battery; (2) the mass and volume ratio of inactive substances in the battery are obviously increased by the aluminum foil and copper foil current collectors with compact structures, and the specific energy and energy density of the battery are obviously reduced; (3) the current collector with a compact structure has poor electric conductivity and thermal conductivity, and the pulse discharge and high-power charge-discharge characteristics of the battery are seriously influenced; (4) the lithium source anode is matched with the non-lithium source cathode, so that the space utilization rate of the battery is greatly reduced, and the volume and mass energy density of the battery are reduced.
In order to solve the problems of high mass-to-mass ratio of the inactive substances, low energy density of the battery, easy falling of the active substances and the like, research and development of a secondary battery which has high volume energy density and high specific energy, meets the requirement of quick charge, simplifies the design and reduces the cost are urgently needed.
Disclosure of Invention
In order to overcome the above problems, the present inventors have devised an electrode sheet for a secondary battery, a secondary battery and a method for manufacturing the same, in which a current collector of a positive electrode and/or a negative electrode is designed to have a porous structure by optimizing a battery structural design and a component selection under a precondition of ensuring battery safety, and a positive electrode or a negative electrode active material is loaded in the porous structure, so that the volume and mass ratio of an inactive material component in the secondary battery can be effectively reduced, and the volume and gravimetric specific energy of the secondary battery can be improved, thereby completing the present invention.
In a first aspect, the present invention provides an electrode tab of a secondary battery, the electrode tab comprising a positive electrode tab and/or a negative electrode tab, the positive electrode tab comprising a positive electrode current collector and a positive electrode active material layer; the negative plate comprises a negative current collector; wherein
The positive electrode current collector and/or the negative electrode current collector have a porous structure.
In a second aspect, the present invention provides a secondary battery comprising the electrode sheet provided in the first aspect, and further comprising an electrolyte which is a liquid electrolyte or a solid electrolyte;
preferably, the solid electrolyte is selected from at least one of lithium titanium phosphate, lithium aluminum titanium phosphate, lithium lanthanum titanium oxide, lithium lanthanum zirconium oxide, lithium aluminum germanium phosphate, sodium vanadium phosphate, sodium titanium phosphate, polyethylene oxide, lithium phosphorus sulfur, lithium germanium phosphorus sulfur, lithium silicon phosphorus sulfur chloride, lithium phosphorus sulfur oxide.
In a third aspect, the present invention provides a method for manufacturing a secondary battery, comprising:
and 3, packaging.
The electrode plate of the secondary battery, the secondary battery and the preparation method thereof have the following beneficial effects:
(1) the current collector of the positive electrode and/or the negative electrode has a porous structure, so that the contact area between the active substance and the current collector can be effectively reduced and increased, the contact acting force between the active substance and the current collector is enhanced, and the active substance is not easy to fall off on the surface of the current collector; meanwhile, the heat conduction efficiency and the electronic conduction path are improved, so that the power characteristic and the cycle life of the battery are improved;
(2) the current collector of the positive electrode and/or the negative electrode is of a porous structure, so that the volume and mass ratio of an inactive substance assembly in the battery can be effectively reduced, the volume and weight ratio energy of the battery can be obviously improved, and the cost is reduced;
(3) the current collector of the positive electrode and/or the negative electrode is of a porous structure, and can reserve a storage space for lithium/sodium on the positive electrode side in the charging process, so that an active material layer of the negative electrode is omitted, the design of the battery is simplified, the volume and mass ratio energy of the battery are further improved, and the cost is reduced;
(4) the invention adopts the ion conductor coating or the ceramic coating diaphragm, can effectively improve the electrolyte wettability, the thermal shrinkage characteristic and the ion conduction characteristic of the battery, and further improve the safety and the power characteristic of the battery;
(5) the invention adopts the solid electrolyte, saves components of a separation film and a liquid electrolyte, effectively improves the high-temperature safety, simplifies the design of the battery and reduces the cost;
(6) according to the invention, the lithium source-free active material is used as the positive electrode active material, and the lithium source is integrated into the negative electrode porous current collector in a physical or chemical mode, such as electrochemical deposition, physical melting, chemical lithiation and the like, so that the volume and specific energy density of the battery can be improved.
Drawings
Fig. 1 illustrates a schematic view of a conventional secondary battery structure;
fig. 2 is a schematic view showing the structure of a secondary battery prepared in example 1 of the present invention;
fig. 3 shows a schematic view of the structure of the positive and/or negative porous current collectors of the secondary battery of the present invention;
fig. 4 shows a schematic view of the structure of the positive and/or negative porous current collector of the secondary battery according to the present invention.
The reference numbers illustrate:
1-positive plate;
11-positive current collector;
12-positive electrode active material layer;
2-an electrolyte;
3-negative current collector;
100-conventional secondary battery positive plate
110-positive electrode current collector
120-positive electrode active material
200-electrolyte
300-traditional secondary battery negative plate
310-negative electrode active material
320-negative electrode Current collector
Detailed Description
The invention is explained in more detail below with reference to the drawings and preferred embodiments. The features and advantages of the present invention will become more apparent from the description.
The basic working principle of the lithium ion secondary battery commonly used at present is as follows: during charging, lithium ions reach the particle surface from the inside of positive electrode material particles in the positive electrode sheet active material layer in a diffusion mode, then pass through the porous diaphragm by surface migration and liquid electrolyte transportation to reach the negative electrode material particle surface of the negative electrode sheet active material layer, meanwhile, electrons are transported to the negative electrode particle surface from the positive electrode material particles through the positive electrode current collector aluminum foil and an external circuit, and are diffused to the inside of the negative electrode material particles after being compounded with the lithium ions transferred from the positive electrode, so that the charging process is completed; the discharge process is reversed.
In the working principle of the battery, the positive current collector and the negative current collector respectively play roles in supporting an electrode active substance layer and conducting electrons, when the battery is charged, the positive active substance layer provides lithium ions, the liquid electrolyte plays a role in transporting ions in the battery, the diaphragm plays a role in isolating a positive plate from a negative plate, and the negative active substance layer is mainly used for storing electrons and ions from the positive electrode.
As shown in fig. 1, a conventional lithium ion battery cell mainly includes a positive electrode sheet 100, an electrolyte 200, a negative electrode sheet 300, and a sealing material. The positive plate 100 is composed of a compact-structure aluminum foil current collector and a lithium-containing active material layer coated on the current collector, the electrolyte 200 is made by dissolving lithium salt (such as lithium hexafluorophosphate) in an organic solvent (ethylene carbonate, ethyl methyl carbonate, propylene carbonate, and the like), and the negative plate 300 is composed of a compact-structure copper foil current collector and a lithium-free active material layer coated on the current collector. Since the electrolyte 200 is a liquid electrolyte, a separator, which is often a polyolefin porous film, must be provided between the positive electrode sheet 100 and the negative electrode sheet 300.
In a first aspect, the present invention provides an electrode tab of a secondary battery. The electrode plate comprises a positive plate and/or a negative plate; the positive plate comprises a positive current collector and a positive active material layer; the negative plate comprises a negative current collector; wherein the positive electrode current collector and/or the negative electrode current collector are in a porous structure.
According to the invention, the substrate of the positive current collector is a metal foil or alloy resistant to oxidation and to corrosion by organic electrolytes. Preferably, the base material of the positive electrode current collector includes, but is not limited to, at least one of aluminum foil, aluminum alloy containing 90% or more of aluminum, stainless steel, titanium alloy, nickel alloy, iron alloy, MOF structure material, and the like. More preferably at least one of aluminum foil, nickel foil and aluminum alloy containing 90% or more of aluminum, such as nickel foil or aluminum foil.
Preferably, the substrate of the negative electrode current collector is at least one of copper foil and its alloy, nickel foil and its alloy, titanium foil and its alloy, and porous carbon felt, preferably copper foil or its alloy.
According to the present invention, the thickness of the base material of the positive electrode current collector is 6.0 to 30.0 μm, preferably 10.0 to 20.0 μm.
According to the invention, the thickness of the substrate of the negative current collector is 3.0-15.0 μm, preferably 4.0-10.0 μm.
When the current collector foil is thick (e.g., greater than 30.0 μm), the cost of the battery is significantly increased, and the specific energy and energy density of the battery are significantly decreased; when the current collector is too thin (e.g., less than 3.0 μm), the tensile strength of the current collector is significantly reduced, the adhesion of the active material when applied to the current collector is poor, the active material is prone to chipping and dusting, and the battery cycle performance is significantly deteriorated.
In a preferred embodiment of the present invention, the porous structure of the positive electrode current collector and/or the negative electrode current collector is at least one of a circular hole, a square hole, and a foam hole.
In this embodiment, the positive electrode current collector has a porous structure, or the negative electrode current collector has a porous structure, or both the positive electrode current collector and the negative electrode current collector have a porous structure. Preferably, when the positive and negative electrode current collectors have a porous structure at the same time, the porous structures of the two are the same.
In a preferred embodiment of the invention, the pore area S of the porous structure1And the area S of the non-hole2Is controlled at S1:S2(10-90): (90: 10), preferably 50: 50.
it is to be noted that the porous structure has a pore area S1And the area S of the non-hole2The ratio of (a) should not be too large or too small, if the ratio is too large, the pore structure is too much, the mechanical strength of the positive current collector and/or the negative current collector is influenced, the long-term use strength cannot be borne, and the safety is insufficient; if the ratio is too small, the inactive material mass ratio is still high, so that the battery performance cannot be optimized. Therefore, the mass ratio of the inactive substances can be effectively reduced through the control of the area ratio, and the battery capacity is improved on the basis of ensuring the safety.
According to a preferred embodiment of the present invention, the pore diameter of the porous structure of the positive electrode current collector and/or the negative electrode current collector is 0.01 to 3.00mm, and the pore distance is 0.01 to 3.00 mm.
Specifically, as shown in fig. 3, when the porous structure of the positive electrode current collector and/or the negative electrode current collector is a circular hole, the diameter of the circular hole is 0.1-1.5 mm, and the hole distance between the circular holes is 0.1-1.5 mm. Preferably, the aperture is 0.5-1.0 mm, and the hole spacing is 0.5-1.0 mm. If the aperture is larger, the tensile strength of the current collector is rapidly reduced; the aperture is smaller, the processing cost of the current collector is obviously increased, and the improvement range of the specific energy and the energy density of the battery is limited.
Specifically, as shown in fig. 4, when the porous structure of the positive electrode current collector and/or the negative electrode current collector is square holes, the diameter of each square hole is 0.5-2.0 mm, and the hole distance between the square holes is 0.5-2.0 mm. Preferably, the aperture is 1.0-1.5 mm, and the hole spacing is 1.0-1.5 mm.
The square holes and the round holes have positive effects on improving the adhesion of active substances, reducing the mass ratio of inactive substances, reducing the cost, improving the conductivity and the like. However, there are also minor differences between square and round holes, for example, square holes are generally less stable in pore structure than round holes.
It is noted that the conventional positive and negative electrode current collectors have a dense structure, which results in a high mass fraction of inactive materials, affecting the thermal conduction efficiency and the electron conduction path, and further affecting the power characteristics and cycle life of the battery. According to the invention, the compact structure is changed into the porous structure, so that the volume and mass ratio of the active material assembly in the battery can be reduced, the battery cost is reduced, meanwhile, the contact area between the positive/negative electrode active material and the positive/negative electrode current collector can be effectively reduced and improved, the adhesion between the active material layer and the current collector is obviously improved, on the basis of increasing the active material ratio, the active material is not easy to fall off, and the power characteristic and the cycle life of the battery are further improved.
In the present invention, the positive electrode active material layer is formed of a metal oxide.
Preferably, the metal oxide includes, but is not limited to, at least one of lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganese oxide, lithium nickel manganese oxide, cobalt dioxide, titanium dioxide, molybdenum dioxide, nickel dioxide, manganese dioxide, titanium disulfide, molybdenum disulfide, ferrous sulfide, iron disulfide, iron phosphate, iron manganese phosphate, iron trifluoride, carbon fluoride, sodium vanadium phosphate, sodium cobalt oxide, sodium iron copper manganese oxide, titanium sodium phosphate,
more preferably, the metal oxide is a lithium source-free active material selected from at least one of iron trifluoride, titanium dioxide, molybdenum dioxide, and nickel dioxide.
It is noteworthy that the active lithium required for conventional lithium ion batteries is mainly provided by the positive active material, such as LiCoO2、LiFePO4、LiMn2O4And the like, lithium is not contained in the negative electrode active material; during charging, lithium in the positive active material is extracted from the positive electrode, passes through the diaphragm and enters the negative active material layer, and charging is completed. According to thermodynamic calculation, under the condition of the same crystal structure, compared with a lithium-containing material system, the lithium-free cathode material has higher theoretical specific capacity.
Therefore, the present invention preferably employs an active material such as FeF without a lithium source3、CoO2、MnO2Etc. as the positive electrode; the lithium source is integrated into the current collector of the negative electrode porous structure through physical or chemical methods such as electrochemical deposition, physical melting, chemical lithiation and the like, so that the positive electrode does not contain lithium and the negative electrode contains lithium, and the volume and the specific energy density of the battery can be greatly improved.
In a preferred embodiment of the present invention, the negative electrode sheet further includes:
and a negative electrode active material layer formed of at least one of active lithium, a lithium alloy, active sodium, a lithium silicon alloy, graphite, and a lithium-containing compound thereof.
Wherein the active lithium comprises LiC6、LiC12、LiC24Etc.; the active sodium includes metallic sodium.
In the present invention, in an aspect, when the negative electrode current collector has a porous structure, the negative electrode sheet may not include the negative electrode active layer. The porous structure can reserve a storage space for the positive lithium or sodium ions in the charging process, namely, when charging is carried out, the lithium ions provided by the positive active material layer are directly embedded into the porous structure of the negative current collector, the space structure of the negative electrode plate is saved, and the volume space of the secondary battery is saved.
On the other hand, when the negative current collector is in a porous structure, the negative plate can further comprise a negative active material layer, wherein the negative active material layer is loaded in the porous structure, namely, during charging, lithium ions provided by the positive active material layer are embedded into the negative active material layer, so that the space structure of the negative plate is also saved, and the volume and the space of the secondary battery are saved.
In the invention, the preparation process of the positive plate comprises the following steps: preparing a positive active material layer on a positive current collector,
preferably, the positive electrode active material layer is formed by one or more of spraying, space coating (equal space extrusion coating), sputtering with a mask structure (mask plate sputtering), pulsed laser deposition, atomic layer deposition, electrochemical deposition, pulsed laser deposition, 3D printing, rolling and the like of the positive electrode active material component.
More preferably, the preparation process of the positive electrode sheet may be: mixing a positive electrode active substance, a conductive additive and a binder to prepare slurry, coating the slurry on a positive electrode current collector, and drying to obtain a positive plate formed by the positive electrode active substance layer and the positive electrode current collector, wherein the positive plates with different performances are formed according to different structures of the positive electrode current collector;
the positive electrode active substance, the conductive additive and the binder are weighed according to the mass ratio, are gradually added into a solvent (such as NMP), the solid content is controlled to be 40% -60%, the mixture is uniformly stirred to obtain a mixed slurry, and the mixed slurry is coated on a positive electrode current collector.
More preferably, the preparation process of the positive electrode sheet may be: the positive electrode active substance, the conductive additive and the binder are mixed according to the mass ratio to form a dry powder mixture, the dry powder mixture is coated on a positive electrode current collector under the condition of high temperature (120-250 ℃) to obtain a positive electrode sheet formed by a positive electrode active substance layer and the positive electrode current collector, and the positive electrode sheets with different performances are formed according to different structures of the positive electrode current collector. For example, the circular porous structure can be obtained by space coating, sputtering with a mask structure, rolling, pulsed laser deposition, chemical vapor deposition, electrochemical deposition, atomic layer deposition, 3D printing, and the like.
According to a preferred embodiment of the present invention, the binder is an organic polymer material that can be used as a binder for a positive electrode material of a secondary battery, and preferably, the binder is one or more selected from polyvinylidene fluoride, polytetrafluoroethylene, polymethyl acrylate, polyacrylonitrile, sodium carboxymethylcellulose, and styrene butadiene rubber emulsion.
According to a preferred embodiment of the present invention, the conductive additive is a carbon material, preferably at least one selected from carbon black, carbon nanotubes, graphene, acetylene black, ketjen black, and the like, for example, carbon black.
In a second aspect, the present invention provides a secondary battery. The battery includes the electrode sheet of the first aspect, and further includes:
an electrolyte, which is a liquid electrolyte or a solid electrolyte;
preferably, the solid electrolyte is selected from at least one of lithium titanium phosphate, lithium aluminum titanium phosphate, lithium lanthanum titanium oxide, lithium lanthanum zirconium oxide, lithium aluminum germanium phosphate, sodium vanadium phosphate, sodium titanium phosphate, polyethylene oxide, lithium phosphorus sulfur, lithium germanium phosphorus sulfur, lithium silicon phosphorus sulfur chloride, lithium phosphorus sulfur oxide.
The secondary battery of the present invention is applicable to, but not limited to, a secondary battery based on a solid electrolyte as a working medium, such as lithium ions, sodium ions, magnesium ions, and aluminum ions.
In the present invention, when the electrolyte is a solid electrolyte, the separator and the liquid electrolyte assembly can be omitted, thereby effectively improving the high-temperature safety of the secondary battery, simplifying the design of the secondary battery, and reducing the cost.
Preferably, the liquid electrolyte is 1mol/LLIPF6/(EC (ethylene carbonate) + DMC (diethyl carbonate) + EMC (ethyl methyl carbonate)), where VEC:VDMC:VEMC＝1:1:1。
According to a preferred embodiment of the present invention, when the electrolyte is a liquid electrolyte, the secondary battery further includes a separator disposed between the positive electrode tab and the negative electrode tab for separating the positive electrode active material and the negative electrode active material; wherein
The isolating film comprises a substrate and a coating, wherein the coating covers at least one surface of the substrate.
Preferably, the matrix is formed from at least one layer of at least one of polyethylene, polypropylene, polyaramid, polytetrafluoroethylene and polyacrylonitrile.
Preferably, the coating is a ceramic coating of an ionic conductor.
More preferably, the ceramic coating of the ion conductor is formed of at least one of lithium germanium phosphate, lithium aluminum germanium phosphate, lithium titanium phosphate, lithium aluminum titanium phosphate, lithium lanthanum zirconium oxygen, lithium lanthanum titanium oxygen, aluminum oxyhydroxide, aluminum oxide, titanium dioxide.
In the invention, the isolating membrane is designed into the ceramic coating diaphragm of the ionic conductor, so that the electrolyte wettability and the thermal shrinkage characteristic of the battery, namely the ionic conduction characteristic, can be effectively improved, and the safety and the power characteristic of the battery are further improved.
In a third aspect, the present invention provides a method for producing a secondary battery, preferably the secondary battery of the second aspect, comprising:
the method comprises the following steps of 1, preparing a positive plate and a negative plate, wherein the positive plate comprises a positive current collector and a positive active material, the negative plate comprises a negative current collector, and the positive current collector and/or the negative current collector are in a porous structure.
In a preferred embodiment of the present invention, in step 1:
when the positive electrode current collector has a porous structure, the positive electrode active material is filled in the porous structure of the positive electrode current collector.
Preferably, the negative electrode sheet further includes a negative electrode active material layer, and when the negative electrode current collector has a porous structure, the negative electrode active material is filled in the porous structure of the negative electrode current collector.
In the invention, on one hand, when the negative current collector is in a porous structure, the negative plate does not include the negative active layer, that is, during charging, lithium ions provided by the positive active material layer are directly embedded into the porous structure of the negative current collector, so that the space structure of the negative plate is saved, and the volume and space of the secondary battery are saved. On the other hand, when the negative current collector is in a porous structure, the negative sheet can further comprise a negative active material layer, wherein the negative active materials are loaded in the porous structure, namely, when in charging, lithium ions provided by the positive active material layer are inserted into the negative active materials, and the space structure of the negative sheet is also saved, so that the volume space of the secondary battery is saved.
And 2, injecting electrolyte.
According to a preferred embodiment of the present invention, when the electrolyte is a lithium titanium phosphate solid electrolyte, illustratively, when the solid electrolyte is selected from lithium titanium phosphate, the solid electrolyte is prepared by: lithium carbonate, titanium dioxide, alumina, lithium dihydrogen phosphate are mixed according to the target compound Li1+xAlxTi2-x(PO4)3Requirement of (2) Li: al: ti: p ═ 1+ x: x: (2-x): 3, wherein x is more than or equal to 0 and less than 0.45,
then uniformly mixing the mixture by using a high-speed mixer or a ball mill,
calcining for 10 hours at the high temperature of 800-900 ℃,
pulverizing calcined material by mechanical pulverization to micrometer scale (D)50Controlled at 1-5 μm), followed by grinding with a sand mill to a particle size D50Between 0.1 and 0.3 μm for use.
In a preferred embodiment of the present invention, when the electrolyte is a liquid electrolyte, before step 2, the method further comprises inserting a separator.
Specifically, a positive plate, a separation film and a negative plate are arranged in a packaging material in a laminated or winding mode, and then an electrolyte is injected under the condition of negative pressure inert atmosphere, wherein the amount of the liquid electrolyte is controlled to be (1.0-3.5) g/Ah based on the fact that the electrode plate and the separation film can be completely soaked.
And 3, packaging.
According to a preferred embodiment of the present invention, the secondary battery has a square, cylindrical, button-shaped or aluminum plastic film configuration in outer shape.
According to the present invention, the secondary battery including the porous structure positive electrode current collector and/or the porous structure negative electrode current collector has a high battery capacity compared to the conventional secondary battery, and can significantly improve the cycle characteristics of the battery; and has higher energy density on the premise that the rate characteristic is not obviously influenced. For example, the test voltage range is 2.75V-4.20V, the test temperature is 45 ± 2 ℃, the battery capacity ratio of the secondary battery comprising the porous structure positive current collector 11 and the porous structure negative current collector 3 is improved by more than 1.2%, and the first coulombic efficiency is improved by more than 1% on the premise that the rate characteristic is basically not influenced.
Examples
Example 1
A secondary battery includes a positive electrode sheet 1, an electrolyte 2, and a negative electrode current collector 3, the positive electrode sheet 1 including a positive electrode current collector 11 and a positive electrode active material layer 12, as shown in fig. 2.
Wherein, the positive current collector 11 is an aluminum foil with a thickness of 15 μm, the porous structure of the positive current collector 11 is a circular hole, the aperture of the circular hole is 0.5mm, and the hole pitch is 0.5mm, as shown in fig. 3;
the active material of the positive electrode active material layer 12 is FeF3The binder is polyvinylidene fluoride, and the conductive additive is acetylene black, wherein the FeF3The mass percentage of the polyvinylidene fluoride to the acetylene black is 95:3: 2.
The electrolyte 2 is solid electrolyte, specifically lithium aluminum titanium phosphate, D of lithium aluminum titanium phosphate500.1-0.3 μm;
the negative current collector 3 is a copper foil with the thickness of 8 mu m, the porous structure of the negative current collector 3 is a circular hole, the aperture of the circular hole is 0.5mm, the hole pitch is 0.5mm, and the porous structure of the negative current collector 3 is loaded with negative active material metallic lithium with the thickness of 8 mu m.
Example 2
A similar manufacturing method to that of example 1, except that the positive electrode current collector 11 was an aluminum foil having a dense structure and a thickness of 15 μm.
Example 3
A similar manufacturing method to that of example 1, except that the negative electrode current collector 3 is a copper foil having a dense structure of 8 μm in thickness. The negative electrode sheet further included metallic lithium as a negative electrode active material having a thickness of 8 μm.
Example 4
A production method similar to that of example 1 is mainly different in that the active material of the positive electrode active material layer 12 is lithium cobaltate and the negative electrode active material is graphite.
Example 5
The preparation method similar to that of example 1 is mainly different in that the active materials of the positive electrode active material layer 12 are lithium iron phosphate and a non-negative electrode active material.
Example 6
A preparation similar to that of example 1, the difference being essentially that the electrolyte 2 is a liquid electrolyte, in particular 1mol/LLIPF6/(EC + EMC + DEC) and a 12 μm thick spacer film.
Example 7
The preparation method is similar to that of example 1, and the difference is mainly that the aperture of the circular holes and the hole spacing are different, and the aperture of the circular holes is 1.0mm, and the hole spacing is 1.0 mm.
Comparative example 1
A similar preparation method to that of example 1, except that the positive electrode current collector 11 is an aluminum foil having a dense structure and a thickness of 15 μm; and the negative current collector is a copper foil with a compact structure and a thickness of 8 mu m, and the negative plate also comprises a negative active material metallic lithium with a thickness of 8 mu m.
Examples of the experiments
Experimental example 1
Electrochemical performance tests were performed on examples 1 to 7 and comparative example 1, and the test results are shown in table 1 below.
From the experimental results in table 1, it can be seen that the positive and negative current collectors in example 1 all adopt a porous structure, so that the secondary battery has high energy density, discharge specific capacity, cyclicity, and first charge-discharge efficiency. The active material or solid electrolyte without a lithium source used in example 1 enables the secondary battery to have an improved specific discharge capacity and energy density. In addition, it can be seen from examples 1 and 7 that when the pore diameters of the circular holes are slightly different, the electrical properties of the secondary battery are not greatly different.
TABLE 1
The invention has been described in detail with reference to the preferred embodiments and illustrative examples. It should be noted, however, that these specific embodiments are only illustrative of the present invention and do not limit the scope of the present invention in any way. Various modifications, equivalent substitutions and alterations can be made to the technical content and embodiments of the present invention without departing from the spirit and scope of the present invention, and these are within the scope of the present invention.
Claims (10)
1. The electrode plate of the secondary battery is characterized by comprising a positive plate and/or a negative plate, wherein the positive plate comprises a positive current collector and a positive active material layer; the negative plate comprises a negative current collector; wherein
The positive electrode current collector and/or the negative electrode current collector are in a porous structure.
2. The electrode sheet as defined in claim 1,
the porous structure of the positive electrode current collector and/or the negative electrode current collector is at least one of a round hole, a square hole and a foam hole;
preferably, the ratio of the area of a pore in the porous structure of the positive electrode current collector to the area of a non-pore in the porous structure of the negative electrode current collector is (10-90): (90: 10);
preferably, the pore diameter of the porous structure is 0.01-3.00 mm, and the pore spacing is 0.01-3.00 mm.
3. The electrode sheet of claim 1, wherein:
the positive electrode active material layer is formed of a metal oxide, and preferably, the metal oxide includes at least one of lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganese oxide, lithium nickel manganese oxide, cobalt dioxide, titanium dioxide, molybdenum dioxide, nickel dioxide, manganese dioxide, titanium disulfide, molybdenum disulfide, ferrous sulfide, iron disulfide, iron phosphate, iron manganese phosphate, iron trifluoride, carbon fluoride, sodium vanadium phosphate, sodium cobalt oxide, sodium iron copper manganese oxide, and titanium sodium phosphate.
4. The electrode sheet of claim 1, wherein: the negative electrode sheet further comprises:
and a negative electrode active material layer formed of at least one of active lithium, a lithium alloy, a lithium silicon alloy, active sodium, graphite, and a lithium-containing compound thereof.
5. A secondary battery preferably comprising the electrode sheet according to any one of claims 1 to 4, characterized by further comprising:
an electrolyte, which is a liquid electrolyte or a solid electrolyte;
preferably, the solid electrolyte is selected from at least one of lithium titanium phosphate, lithium aluminum titanium phosphate, lithium lanthanum titanium oxide, lithium lanthanum zirconium oxide, lithium aluminum germanium phosphate, sodium vanadium phosphate, sodium titanium phosphate, polyethylene oxide, lithium phosphorus sulfur, lithium germanium phosphorus sulfur, lithium silicon phosphorus sulfur chloride, lithium phosphorus sulfur oxide.
6. The secondary battery according to claim 5, wherein when the electrolyte is a liquid electrolyte, the secondary battery further comprises:
a release film comprising a substrate and a coating covering at least one surface of the substrate,
preferably, the matrix is formed from at least one layer of at least one of polyethylene, polypropylene, polytetrafluoroethylene and polyacrylonitrile.
7. The secondary battery according to claim 6, wherein the coating is a ceramic coating of an ion conductor;
preferably, the ceramic coating of the ion conductor is formed of at least one of lithium germanium phosphate, lithium aluminum germanium phosphate, lithium titanium phosphate, lithium aluminum titanium phosphate, lithium lanthanum zirconium oxygen, lithium lanthanum titanium oxygen, aluminum oxyhydroxide, aluminum oxide, and titanium dioxide.
8. A method for producing a secondary battery, preferably a secondary battery according to claim 6 or 7, comprising:
step 1, preparing a positive plate and a negative plate, wherein the positive plate comprises a positive current collector and a positive active material layer, the negative plate comprises a negative current collector, and the positive current collector and/or the negative current collector are in a porous structure;
step 2, injecting electrolyte;
and 3, packaging.
9. The production method according to claim 8, characterized in that, in step 1:
when the positive electrode current collector is of a porous structure, filling a positive electrode active material in the porous structure of the positive electrode current collector;
preferably, the negative electrode sheet further includes a negative electrode active material layer, and when the negative electrode current collector has a porous structure, the negative electrode active material is filled in the porous structure of the negative electrode current collector.
10. The method according to claim 8,
when the electrolyte is a liquid electrolyte, before the step 2, inserting a separation film is further included.
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