CN114420940A - Current collector for lithium ion secondary battery and preparation method and system thereof - Google Patents
Current collector for lithium ion secondary battery and preparation method and system thereof Download PDFInfo
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- CN114420940A CN114420940A CN202210116819.9A CN202210116819A CN114420940A CN 114420940 A CN114420940 A CN 114420940A CN 202210116819 A CN202210116819 A CN 202210116819A CN 114420940 A CN114420940 A CN 114420940A
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- 238000002360 preparation method Methods 0.000 title claims abstract description 39
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title abstract description 30
- 229910001416 lithium ion Inorganic materials 0.000 title abstract description 30
- 239000000835 fiber Substances 0.000 claims abstract description 83
- 238000003763 carbonization Methods 0.000 claims abstract description 30
- 229920005594 polymer fiber Polymers 0.000 claims abstract description 20
- 230000003647 oxidation Effects 0.000 claims abstract description 19
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 19
- 229920000642 polymer Polymers 0.000 claims abstract description 10
- 238000012545 processing Methods 0.000 claims abstract description 8
- 238000010041 electrostatic spinning Methods 0.000 claims abstract description 6
- 239000004743 Polypropylene Substances 0.000 claims description 34
- -1 polypropylene Polymers 0.000 claims description 34
- 229920001155 polypropylene Polymers 0.000 claims description 34
- 238000009941 weaving Methods 0.000 claims description 20
- 238000009987 spinning Methods 0.000 claims description 15
- 238000000034 method Methods 0.000 claims description 8
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 5
- 229910052744 lithium Inorganic materials 0.000 claims description 5
- 229920002125 Sokalan® Polymers 0.000 claims description 2
- 239000007772 electrode material Substances 0.000 claims description 2
- 239000004584 polyacrylic acid Substances 0.000 claims description 2
- 229920002239 polyacrylonitrile Polymers 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims 1
- 238000001179 sorption measurement Methods 0.000 description 25
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 23
- 229910052782 aluminium Inorganic materials 0.000 description 23
- 239000011888 foil Substances 0.000 description 23
- 238000004804 winding Methods 0.000 description 15
- 238000001816 cooling Methods 0.000 description 14
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 13
- 230000009471 action Effects 0.000 description 13
- 238000002074 melt spinning Methods 0.000 description 13
- 229910052799 carbon Inorganic materials 0.000 description 12
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 12
- 238000000576 coating method Methods 0.000 description 9
- 239000011248 coating agent Substances 0.000 description 8
- 239000002033 PVDF binder Substances 0.000 description 6
- 239000006256 anode slurry Substances 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 6
- 238000001035 drying Methods 0.000 description 6
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 6
- 238000005096 rolling process Methods 0.000 description 6
- 238000012360 testing method Methods 0.000 description 5
- 239000011149 active material Substances 0.000 description 4
- 239000006258 conductive agent Substances 0.000 description 4
- 238000002844 melting Methods 0.000 description 4
- 230000008018 melting Effects 0.000 description 4
- 230000001590 oxidative effect Effects 0.000 description 4
- 239000013543 active substance Substances 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 239000007774 positive electrode material Substances 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 239000000853 adhesive Substances 0.000 description 2
- 230000001070 adhesive effect Effects 0.000 description 2
- 239000003575 carbonaceous material Substances 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000010287 polarization Effects 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 230000002238 attenuated effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000009954 braiding Methods 0.000 description 1
- 239000006229 carbon black Substances 0.000 description 1
- 239000002041 carbon nanotube Substances 0.000 description 1
- 229910021393 carbon nanotube Inorganic materials 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000003486 chemical etching Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000005056 compaction Methods 0.000 description 1
- 238000003851 corona treatment Methods 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 230000009881 electrostatic interaction Effects 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000000523 sample Substances 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
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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
- H01M4/66—Selection of materials
-
- 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
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/64—Carriers or collectors
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- 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)
- Cell Electrode Carriers And Collectors (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention relates to the field of battery current collectors, in particular to a current collector for a lithium ion secondary battery and a preparation method and a system thereof. The preparation method specifically comprises the following steps: carrying out electrostatic spinning on the polymer melt to obtain polymer fibers, and then preparing the polymer fibers into fiber aggregates; then, sequentially carrying out pre-oxidation and carbonization on the fiber aggregate to obtain the current collector; wherein, in the electrostatic spinning, the temperature is 180-230 ℃, and the speed is 10-30 m/min; the diameter of the polymer fiber is 0.2-0.4 μm. The invention also provides a processing system of the current collector for the lithium ion secondary battery. The prepared current collector and the pole piece have strong bonding force and low pole piece impedance; the lithium ion secondary battery prepared by the current collector has lower internal resistance, and can improve the charge and discharge performance and the rate capability of the lithium ion secondary battery.
Description
Technical Field
The invention relates to the field of battery current collectors, in particular to a current collector for a lithium ion secondary battery and a preparation method and a system thereof.
Background
Aluminum foil is a positive electrode current collector of a lithium ion secondary battery, but has the following problems: contact impedance exists between the aluminum foil and the interface of the positive active material, so that the polarization is overlarge and the heating is heavier in the charging and discharging processes; the aluminum foil, the active material and the conductive agent have weak bonding force, the active material continuously collides and shrinks along with the charging and discharging, the active material is peeled from the aluminum foil, and the capacity and the service life are accelerated to be attenuated; moreover, the electrolyte reacts with the aluminum foil, which also accelerates the degradation of the battery life.
In order to solve the above problems, in recent years, a great deal of modification research on aluminum foils, such as chemical etching, corona treatment, carbon-coated surface and the like, has been performed, wherein aluminum foils with carbon-coated surfaces (carbon-coated aluminum foils for short) have been widely used because the contact impedance between the positive current collector and the active material is reduced, the polarization is reduced, and the charge-discharge performance and the rate capability of the battery are improved to a certain extent.
In the carbon-coated aluminum foil, the commonly used conductive carbon materials mainly comprise carbon black, carbon nano tubes and the like, and the dispersibility of the conductive carbon materials in water is poor, so that the coating is difficult to be uniformly and finely coated on the aluminum foil during the coating process in the preparation of the carbon-coated aluminum foil, the bonding strength of the coating and the aluminum foil and the stability of a current collector are reduced, and the phenomenon of water jump in a circulating mode is easy to occur in the circulating process of a lithium ion secondary battery prepared from the carbon-coated aluminum foil.
Disclosure of Invention
The first purpose of the invention is to provide a preparation method of a current collector, which specifically comprises the following steps:
carrying out electrostatic spinning on the polymer melt to obtain polymer fibers, and then preparing the polymer fibers into fiber aggregates; then, sequentially carrying out pre-oxidation and carbonization on the fiber aggregate to obtain the current collector;
wherein, in the electrostatic spinning, the temperature is 180-230 ℃, and the speed is 10-30 m/min; the diameter of the polymer fiber is 0.2-0.4 μm.
The current collector prepared by the method has strong binding power with the pole piece and low impedance of the pole piece; the lithium ion secondary battery prepared by adopting the current collector has lower internal resistance, and can improve the charge and discharge performance and the rate capability of the lithium ion secondary battery.
As a preferred embodiment of the invention, the polymer melt is any one or more of polypropylene, polyacrylic acid and polyacrylonitrile.
In a preferred embodiment of the present invention, the porosity of the fiber aggregate is 40 to 85%.
The invention discovers that under the porosity, the positive active substance can enter the pores of the current collector and fully contact with the current collector, so that the bonding strength of the positive active substance and the current collector is improved, and the contact resistance of the positive active substance and the current collector is reduced.
As a preferred embodiment of the present invention, the preparation of the fiber aggregate specifically includes:
collecting the polymer fibers under the pressure of-0.1 to-0.01 MPa and the voltage of 20 to 50kV to obtain the fiber aggregate.
The fiber aggregate is collected under the conditions, so that the porosity of the fiber aggregate can be controlled to be 40-85%, and the performance of the fluid aggregate is maximized.
Preferably, the collection may be performed in an electrostatic adsorption element; in the electrostatic adsorption element, the electrostatic filament swinging voltage is 20-50 kV, and the adsorption wind pressure is-0.1 to-0.01 MPa.
In a preferred embodiment of the invention, the pre-oxidation temperature is 200-400 ℃; the carbonization temperature is 1500-1800 ℃.
Under the pre-oxidation temperature and the carbonization temperature, the porosity of the obtained current collector can be controlled to be 30-70%, the bonding strength of the positive active material and the current collector can be further improved, the contact resistance of the positive active material and the current collector is further reduced, and the performance of the prepared battery is improved.
The second purpose of the invention is to provide a current collector prepared by the preparation method.
By using the current collector, no conductive agent is added into the electrode, and the internal resistance of the prepared battery is equivalent to that of the battery prepared by using the carbon-coated aluminum foil, so that the material cost is reduced.
Preferably, the porosity of the current collector is 30-70%, and/or the thickness is 10-20 μm.
A third object of the present invention is to provide an electrode made of the current collector and the electrode active material prepared according to the present invention.
The fourth purpose of the invention is to provide a lithium battery, wherein the electrode of the lithium battery comprises the current collector prepared by the preparation method.
The lithium battery prepared by the current collector has low internal resistance, and can improve the charge and discharge performance and rate capability of the lithium battery.
The fifth purpose of the invention is to provide a processing system for realizing the preparation method of the current collector, which comprises a fiber weaving device, a pre-oxidation device and a carbonization device which are sequentially connected;
wherein the fiber weaving device comprises a spinning unit and a fiber aggregate preparation unit;
the spinning unit is used for spinning the polymer melt to obtain polymer fibers;
the fiber aggregate preparation unit is used for preparing the polymer fibers into fiber aggregates.
The outlet of the spinning unit is connected with the inlet of the fiber aggregate preparation unit;
the outlet of the fiber aggregate preparation unit is connected with the inlet of the pre-oxidation device.
The processing system can continuously and completely realize the processing and preparation of the current collector, and is convenient to popularize and apply in industry. The polymer fiber aggregate with proper porosity is prepared by a fiber weaving device, and then the current collector with better performances in all aspects is obtained by a pre-oxidation device and a carbonization device.
Preferably, the fiber aggregate preparation unit contains an electrostatic adsorption element for making the polymer fibers into the fiber aggregate by electrostatic action and adsorption.
Preferably, the fiber weaving device further comprises a melting unit for making the polymer into a polymer melt;
the outlet of the melting unit is connected with the inlet of the spinning unit.
In particular embodiments, a melt spinning machine may be employed to perform the functions of the melting unit and the spinning unit.
Preferably, the processing system further comprises a cooling device and a winding shaft device; and the outlet of the carbonization device is sequentially connected with the cooling device and the winding shaft device.
The invention has the beneficial effects that: the prepared current collector and the pole piece have strong bonding force and low pole piece impedance; the lithium ion secondary battery prepared by the current collector has lower internal resistance, and can improve the charge and discharge performance and the rate capability of the lithium ion secondary battery. In addition, by using the current collector disclosed by the invention, no conductive agent is added into the electrode, and the internal resistance of the prepared battery is equivalent to that of the battery prepared by using the carbon-coated aluminum foil, so that the material cost is reduced.
Drawings
FIG. 1 is a schematic view showing the connection of a processing system according to example 5.
In fig. 1: 1. a fiber braiding device; 2. a pre-oxidation device; 3. a carbonization device; 4. a cooling device; 5. a wind-up shaft device; 11. a melt spinning unit; 12. a fiber aggregate preparation unit; 121. an electrostatic adsorption element.
Detailed Description
The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.
The specific techniques or conditions not indicated in the examples are all conventional methods or techniques or conditions described in the literature of the field or according to the product specifications. The reagents and instruments used are conventional products which are available from normal commercial vendors, not indicated by manufacturers.
Example 1
The embodiment provides a current collector, and a preparation method of the current collector comprises the following specific steps:
(1) carrying out melt spinning on polypropylene in a fiber weaving device to obtain polypropylene fiber; wherein, in the fiber weaving device, the temperature of a melt spinning unit is set to be 210 ℃, the spinning speed is set to be 15 m/min, and the diameter of the polypropylene fiber is controlled to be 0.2-0.4 μm;
polypropylene fiber is subjected to the electrostatic action, the adsorption action and the self temperature action of an electrostatic adsorption unit to form a polypropylene fiber aggregate with the porosity of 82.3 percent and the thickness of 22 mu m; wherein in the electrostatic adsorption unit, the electrostatic swinging voltage is controlled to be 45kV, and the adsorption air is controlled to be-0.02 MPa;
(2) conveying the polypropylene fiber aggregate from the fiber weaving device to a pre-oxidation device for treatment; wherein the treatment temperature is 350 ℃, and the treatment time is 3 min;
(3) pre-oxidizing the polypropylene fiber aggregate, and conveying the polypropylene fiber aggregate to a carbonization device for carbonization; wherein the carbonization temperature is 1600 ℃, the treatment time is 8min, and after carbonization, a current collector is formed, the porosity of the formed current collector is 65.4%, and the thickness of the formed current collector is 17.2 mu m;
(4) and (4) conveying the current collector prepared in the step (3) to a cooling device, cooling to room temperature, and collecting into coils through a winding shaft device.
Further, the present embodiment also provides a lithium ion secondary battery containing the current collector, and the specific preparation process is as follows: and coating the lithium iron phosphate anode slurry on the current collector, drying at 95 ℃, rolling, slitting and winding to obtain the 26650 cylindrical lithium ion secondary battery with the capacity of 4 Ah. Wherein, the proportion of positive pole piece is: by mass fraction, 94% of lithium iron phosphate, 3% of Super P, 3% of PVDF and the compacted density of 2.45g/cm3。
Example 2
The embodiment provides a current collector, and a preparation method of the current collector comprises the following specific steps:
(1) carrying out melt spinning on polypropylene in a fiber weaving device to obtain polypropylene fiber; wherein, in the fiber weaving device, the temperature of a melt spinning unit is set to be 220 ℃, the spinning speed is set to be 10 m/min, and the diameter of the polypropylene fiber is controlled to be 0.2-0.4 μm;
polypropylene fiber is subjected to the electrostatic action, the adsorption action and the self temperature action of an electrostatic adsorption unit to form a polypropylene fiber aggregate with the porosity of 65.8 percent and the thickness of 15 mu m; wherein in the electrostatic adsorption unit, the electrostatic swinging voltage is controlled to be 45kV, and the adsorption air size is controlled to be-0.06 MPa;
(2) conveying the polypropylene fiber aggregate from the fiber weaving device to a pre-oxidation device for treatment; wherein the treatment temperature is 350 ℃, and the treatment time is 5 min;
(3) pre-oxidizing the polypropylene fiber aggregate, and conveying the polypropylene fiber aggregate to a carbonization device for carbonization; wherein the carbonization temperature is 1600 ℃, the treatment time is 8min, and after carbonization, a current collector is formed, the porosity of the formed current collector is 46.1%, and the thickness of the formed current collector is 10.6 mu m;
(4) and (4) conveying the current collector prepared in the step (3) to a cooling device, cooling to room temperature, and collecting into coils through a winding shaft device.
Further, the present embodiment also provides a lithium ion secondary battery containing the current collector, and the specific preparation process is as follows: and coating the lithium iron phosphate anode slurry on the current collector, drying at 95 ℃, rolling, slitting and winding to obtain the 26650 cylindrical lithium ion secondary battery with the capacity of 4 Ah. Wherein, the proportion of positive pole piece is: by mass fraction, 94% of lithium iron phosphate, 3% of Super P, 3% of PVDF and the compacted density of 2.45g/cm3。
Example 3
The embodiment provides a current collector, and a preparation method of the current collector comprises the following specific steps:
(1) carrying out melt spinning on polypropylene in a fiber weaving device to obtain polypropylene fiber; wherein, in the fiber weaving device, the temperature of a melt spinning unit is set to be 210 ℃, the spinning speed is set to be 18 m/min, and the diameter of the polypropylene fiber is controlled to be 0.2-0.4 μm;
polypropylene fiber is subjected to the electrostatic action, the adsorption action and the self temperature action of an electrostatic adsorption unit to form a polypropylene fiber aggregate with the porosity of 42.3 percent and the thickness of 20 mu m; wherein in the electrostatic adsorption unit, the electrostatic swinging voltage is controlled to be 45kV, and the adsorption air size is-0.09 MPa;
(2) conveying the polypropylene fiber aggregate from the fiber weaving device to a pre-oxidation device for treatment; wherein the treatment temperature is 350 ℃, and the treatment time is 5 min;
(3) pre-oxidizing the polypropylene fiber aggregate, and conveying the polypropylene fiber aggregate to a carbonization device for carbonization; wherein the carbonization temperature is 1800 ℃, the treatment time is 8min, and after carbonization, a current collector is formed, the porosity of the formed current collector is 30.7%, and the thickness of the formed current collector is 15.2 mu m;
(4) and (4) conveying the current collector prepared in the step (3) to a cooling device, cooling to room temperature, and collecting into coils through a winding shaft device.
Further, the present embodiment also provides a lithium ion secondary battery containing the current collector, and the specific preparation process is as follows: and coating the lithium iron phosphate anode slurry on the current collector, drying at 95 ℃, rolling, slitting and winding to obtain the 26650 cylindrical lithium ion secondary battery with the capacity of 4 Ah. Wherein, the proportion of positive pole piece is: by mass fraction, 94% of lithium iron phosphate, 3% of Super P, 3% of PVDF and the compacted density of 2.45g/cm3。
Example 4
The embodiment provides a current collector, and a preparation method of the current collector comprises the following specific steps:
(1) carrying out melt spinning on polypropylene in a fiber weaving device to obtain polypropylene fiber; wherein, in the fiber weaving device, the temperature of a melt spinning unit is set to be 210 ℃, the spinning speed is set to be 15 m/min, and the diameter of the polypropylene fiber is controlled to be 0.2-0.4 μm;
polypropylene fiber is subjected to the electrostatic action, the adsorption action and the self temperature action of an electrostatic adsorption unit to form a polypropylene fiber aggregate with the porosity of 82.3 percent and the thickness of 22 mu m; wherein in the electrostatic adsorption unit, the electrostatic swinging voltage is controlled to be 45kV, and the adsorption air is controlled to be-0.02 MPa;
(2) conveying the polypropylene fiber aggregate from the fiber weaving device to a pre-oxidation device for treatment; wherein the treatment temperature is 350 ℃, and the treatment time is 3 min;
(3) pre-oxidizing the polypropylene fiber aggregate, and conveying the polypropylene fiber aggregate to a carbonization device for carbonization; wherein the carbonization temperature is 1600 ℃, the treatment time is 8min, and after carbonization, a current collector is formed, the porosity of the formed current collector is 65.4%, and the thickness of the formed current collector is 17.2 mu m;
(4) and (4) conveying the current collector prepared in the step (3) to a cooling device, cooling to room temperature, and collecting into coils through a winding shaft device.
Further, the present embodiment also provides a lithium ion secondary battery containing the current collector, and the specific preparation process is as follows: and coating the lithium iron phosphate anode slurry on the current collector, drying at 95 ℃, rolling, slitting and winding to obtain the 26650 cylindrical lithium ion secondary battery with the capacity of 4 Ah. Wherein, the proportion of positive pole piece is: by mass fraction, the lithium iron phosphate is 97 percent, the PVDF is 3 percent, and the compaction density is 2.45g/cm3。
Example 5
A processing system of a current collector for a lithium ion secondary battery (a schematic connection relation is shown in figure 1) comprises a fiber weaving device 1, a pre-oxidation device 2, a carbonization device 3, a cooling device 4 and a winding shaft device 5 which are sequentially connected in sequence.
Wherein, fibre weaving device 1 includes: a melt spinning unit 11 and a fiber aggregate preparation unit 12;
the melt spinning unit 11 is used for melting and spinning the polymer to obtain polymer fibers;
the fiber aggregate preparation unit 12 is used for preparing polymer fibers into fiber aggregates; in the fiber aggregate preparation unit 12, an electrostatic adsorption element 121 is contained, and the electrostatic adsorption element 121 is used for making the polymer fibers into the fiber aggregate through electrostatic interaction and adsorption;
the outlet of the melt spinning unit 11 is connected with the inlet of the fiber aggregate preparation unit 12;
the outlet of the fiber aggregate preparation unit 12 is connected with the inlet of the pre-oxidation device 2;
the outlet of the pre-oxidation device 2 is connected with the inlet of the carbonization device 3;
a cooling device 4 and a winding shaft device 5 are sequentially connected at the outlet of the carbonization device 3;
the cooling device 4 cools the prepared high-temperature current collector to room temperature, and finally the cooled current collector is collected into a coil through the winding shaft device 5.
Comparative example 1
The comparative example provides a lithium ion secondary battery, which is specifically prepared by the following steps: and coating the lithium iron phosphate anode slurry on a common carbon-coated aluminum foil current collector, drying at 95 ℃, rolling, slitting and winding to obtain the 26650 cylindrical lithium ion secondary battery with the capacity of 4 Ah. Wherein, the proportion of positive pole piece is: by mass fraction, 94% of lithium iron phosphate, 3% of Super P, 3% of PVDF and the compacted density of 2.45g/cm3。
Comparative example 2
The comparative example provides a lithium ion secondary battery, which is specifically prepared by the following steps: and coating the lithium iron phosphate anode slurry on a common aluminum foil current collector, drying at 95 ℃, rolling, slitting and winding to obtain the 26650 cylindrical lithium ion secondary battery with the capacity of 4 Ah. Wherein, the proportion of positive pole piece is: by mass fraction, 94% of lithium iron phosphate, 3% of Super P, 3% of PVDF and the compacted density of 2.45g/cm3。
Test examples
The lithium ion secondary batteries prepared in the above examples and comparative examples were tested for performance and the results are shown in table 1.
The pole piece adhesion testing method comprises the following steps: cutting the rolled pole piece into 200 x 20mm, sticking high-temperature adhesive paper with the same size on the surface of the pole piece, and stripping at the speed of 1mm/s by using a universal tester, wherein the minimum value in the stripping process is the pole piece adhesive force.
The pole piece impedance test method comprises the following steps: and shearing the rolled pole piece into a square size of 4cm x 8cm, placing the sheared pole piece between probes of a BER2200 tester, applying a pressure of 5MPa, and reading a numerical value.
The battery internal resistance testing method comprises the following steps: and testing the internal resistance of the battery under the condition of 1000Hz by using an RJ3563 internal resistance tester.
Table 1 results of performance testing
As can be seen from table 1, in the lithium ion secondary batteries of examples 1 to 4, compared with the comparative examples, the adhesion of the electrode plate is significantly better than that of the common carbon-coated aluminum foil and the common aluminum foil even without adding a conductive agent, and the impedance of the electrode plate and the internal resistance of the battery are much lower than those of the lithium ion secondary batteries using the common carbon-coated aluminum foil and the common aluminum foil as the current collectors. Therefore, the lithium ion secondary battery adopting the current collector prepared by the invention has better positive plate binding power, plate impedance and battery internal resistance than commercial carbon-coated aluminum foils and common aluminum foils.
Although the invention has been described in detail hereinabove with respect to a general description and specific embodiments thereof, it will be apparent to those skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.
Claims (10)
1. A method of making a current collector, comprising:
carrying out electrostatic spinning on the polymer melt to obtain polymer fibers, and then preparing the polymer fibers into fiber aggregates; then, sequentially carrying out pre-oxidation and carbonization on the fiber aggregate to obtain the current collector;
wherein, in the electrostatic spinning, the temperature is 180-230 ℃, and the speed is 10-30 m/min; the diameter of the polymer fiber is 0.2-0.4 μm.
2. The preparation method of claim 1, wherein the polymer melt is any one or more of polypropylene, polyacrylic acid and polyacrylonitrile.
3. The method according to claim 1 or 2, wherein the porosity of the fiber aggregate is 40 to 85%.
4. The method according to any one of claims 1 to 3, wherein the preparation of the fiber aggregate specifically comprises:
collecting the polymer fibers under the pressure of-0.1 to-0.01 MPa and the voltage of 20 to 50kV to obtain the fiber aggregate.
5. The method according to any one of claims 1 to 4, wherein the pre-oxidation temperature is 200 to 400 ℃; the carbonization temperature is 1500-1800 ℃.
6. A current collector prepared by the preparation method according to any one of claims 1 to 5.
7. The current collector of claim 6, wherein the current collector has a porosity of 30-70% and/or a thickness of 10-20 μ ι η.
8. An electrode comprising the current collector of claim 6 or 7 and an electrode active material.
9. A lithium battery, characterized in that its electrode comprises a current collector according to claim 6 or 7.
10. The processing system for realizing the preparation method of any one of claims 1 to 5, which is characterized by comprising a fiber weaving device, a pre-oxidation device and a carbonization device which are sequentially connected in sequence;
wherein the fiber weaving device comprises a spinning unit and a fiber aggregate preparation unit;
the spinning unit is used for spinning the polymer melt to obtain polymer fibers;
the fiber aggregate preparation unit is used for preparing the polymer fibers into fiber aggregates;
the outlet of the spinning unit is connected with the inlet of the fiber aggregate preparation unit;
the outlet of the fiber aggregate preparation unit is connected with the inlet of the pre-oxidation device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210116819.9A CN114420940B (en) | 2022-02-07 | Current collector for lithium ion secondary battery and preparation method and system thereof |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210116819.9A CN114420940B (en) | 2022-02-07 | Current collector for lithium ion secondary battery and preparation method and system thereof |
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| CN114420940A true CN114420940A (en) | 2022-04-29 |
| CN114420940B CN114420940B (en) | 2024-11-08 |
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| JP2003288902A (en) * | 2002-03-27 | 2003-10-10 | Japan Vilene Co Ltd | Current collecting material for battery and battery using the same |
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