CN114883749A - Fluorine-containing diaphragm, negative electrode interface modification material, method for performing interface modification on negative electrode material and battery - Google Patents
Fluorine-containing diaphragm, negative electrode interface modification material, method for performing interface modification on negative electrode material and battery Download PDFInfo
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- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
- H01M50/451—Separators, membranes or diaphragms characterised by the material having a layered structure comprising layers of only organic material and layers containing inorganic material
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- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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- H01M10/05—Accumulators with non-aqueous electrolyte
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- 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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- H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
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- H01M10/00—Secondary cells; Manufacture thereof
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- H01M10/44—Methods for charging or discharging
- H01M10/446—Initial charging measures
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- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
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- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/446—Composite material consisting of a mixture of organic and inorganic materials
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Abstract
The invention discloses a fluorine-containing diaphragm, a negative electrode interface modification material, a method for performing interface modification on the negative electrode material and a battery. The fluorine-containing diaphragm is obtained by coating fluorine-containing slurry on a substrate and drying; the fluorine-containing slurry comprises fluorine-containing powder, a conductive agent, a binder and N-methyl pyrrolidone. The interface modification method is to charge and discharge the battery at least once by using the fluorine-containing diaphragm as the battery diaphragm. The invention introduces fluorine into the diaphragm material, carries out surface modification on the polymer diaphragm, combines the in-situ controllable growth of LiF, constructs a stable SEI interface layer in situ, improves the stability of the cathode/electrolyte interface, prolongs the cycle life of the battery, and has potential application prospect in the aspects of regulating and controlling lithium deposition, stabilizing the cathode and electrolyte interface and the like of systems such as silicon-based secondary lithium ion batteries, lithium metal secondary batteries and the like.
Description
Technical Field
The invention relates to the technical field of electrochemical energy and new materials, in particular to a fluorine-containing diaphragm, a negative electrode interface modification material, a method for performing interface modification on the negative electrode material and a battery.
Background
The vigorous development of portable electronic devices and electric vehicles has put higher demands on high energy density lithium batteries. The high-silicon-based material has the advantages of high specific capacity (3579 mAh/g), good safety, rich raw materials, environmental friendliness and the like, and is expected to replace/partially replace the current commercial graphite cathode material (372 mAh/g). However, the silicon-based negative electrode has large volume expansion (280%) in the circulation process, so that the surface of the silicon-based material is continuously generated with a solid electrolyte interface layer, the particles of the negative electrode material are crushed, the electrode fails and the like. The newly formed interface layer can continuously consume active lithium ions, so that the loss of active lithium is increased and the coulombic efficiency in the circulation process is low. The current method for improving the silicon-based negative electrode comprises the steps of constructing a stable interface layer between the negative electrode and an electrolyte, using an efficient binder, controlling the particle size, pre-lithiating and the like. Meanwhile, lithium metal is a potential negative electrode material with high specific capacity (3860mAh/g) and low density (0.534 g/cm) 3 ) The standard potential is low (-3.04V), which makes lithium metal a highly desirable negative electrode material. However, lithium metal anodes also suffer from serious anode/electrolyte interface problems, and the application and development of lithium metal anodes are severely hampered by problems such as uneven deposition of lithium and dendrite growth during cycling. The current methods for improving lithium metal negative electrodes include constructing a stable interface layer, solid electrolyte, lithium metal interface modification and the like.
The interface stability of the negative electrode and the electrolyte is an effective strategy for effectively exerting the capacity of the negative electrode material and improving the cycle stability of the negative electrode material. The stable interface layer can reduce the loss of active lithium and improve the cycle performance of the battery. For exampleBintang et al (ACS Applied Materials)&Interfaces 2022, 14, 805) use semi-solid electrolyte, and a stable SEI interface layer is generated on the surface of the silicon negative electrode after pre-circulation, so that the volume expansion of silicon particles is effectively inhibited, and the circulation stability of the silicon-based material is remarkably improved. Cao et al (Nano Energy 2022, 93, 106811) use boron and fluorine rich solid electrolytes to induce the formation of a stable SEI interfacial layer rich in benzene rings and inorganic materials, so that the silicon negative electrode still has a capacity of 1778.7mAh/g after 500 cycles. Zhao et al (Journal of the American Chemical Society 2017, 4, 174) developed a surface fluorination process to generate a dense and uniform LiF interface layer on the surface of lithium metal negative electrode, successfully achieved a high density current of 5mA/cm 2 The next dendrite-free stabilization cycle is 300 times. Gao et al (Nature Materials 2019, 18, 384) have designed a molecular level SEI layer using reactive polymeric composites. The layer consists of polymer lithium salt, lithium fluoride and graphene oxide sheets, and 600 cycles are successfully realized under the condition of 12 mu L/mAh of a poor electrolyte. Li et al (patent application No. CN201910880619.9) can generate a stable SEI layer on the surface of the graphite negative electrode at low temperature by regulating the electrolyte and performing at least one charge-discharge process, thereby effectively promoting the transportation efficiency of lithium ions at low temperature and improving the electrochemical performance of the graphite negative electrode at low temperature. Zhang et al (patent application No. CN201811488787.5) constructed a double-layer solid electrolyte membrane on a lithium metal negative electrode, and contacted with lithium metal to form a lithium fluoride layer and contacted with an electrolyte to form an ether polymer layer, thereby effectively improving the cycle life of the lithium metal battery.
However, the current methods for improving SEI are complex to operate, complex to synthesize and inefficient. At present, a simple, convenient, easy-to-operate and pollution-free strategy is still urgently needed to be found to effectively regulate and control the SEI layer of the cathode/electrolyte interface and improve the stability and safety of the battery.
Disclosure of Invention
In order to solve the technical problems, the invention provides a fluorine-containing diaphragm, a negative electrode interface modification material, a method for performing interface modification on a negative electrode material and a battery.
In order to achieve the purpose, the invention adopts the technical scheme that:
on one hand, the invention provides a fluorine-containing diaphragm which is obtained by coating fluorine-containing slurry on a substrate and drying; the fluorine-containing slurry comprises fluorine-containing powder, a conductive agent, a binder and N-methyl pyrrolidone (NMP).
In a preferred embodiment, the fluorine-containing powder is at least one selected from the group consisting of silver fluoride powder, iron fluoride powder, magnesium fluoride powder, aluminum fluoride powder, zinc fluoride powder, and antimony fluoride powder, and more preferably silver fluoride powder;
preferably, the conductive agent is selected from at least one of conductive carbon black and acetylene black, and is further preferably conductive carbon black;
preferably, the binder is polyvinylidene fluoride (PVDF);
preferably, the substrate is a PP separator or a PE separator, and more preferably a PP separator.
In a preferred embodiment, the fluorine-containing slurry contains 50 to 90 parts by mass of the fluorine-containing powder, and more preferably 70 parts by mass of the fluorine-containing powder; the conductive agent is 5-25 parts by weight, and preferably 20 parts by weight; the mass portion of the binder is 5-25, and the preferable mass portion is 10;
preferably, the mass of the N-methylpyrrolidone (NMP) is 4.1-4.5 times of the total mass of the fluorine-containing powder, the conductive agent and the binder.
Preferably, the drying is performed at 50-60 ℃ for 10-12 h;
preferably, the thickness of the coating is 2-100 μm; the smaller the thickness of the coating, the better the cycle performance of the battery prepared from the fluorine-containing separator, and the more thick the coating can accelerate the degradation of the battery.
In another aspect, the invention provides the use of the fluorine-containing separator in the preparation of a battery;
preferably, the battery is a silicon-based secondary lithium ion battery or a lithium metal secondary battery;
preferably, the electrolyte of the battery is selected from ester-based or ether-based electrolytes.
In another aspect, the present invention provides a method for performing interface modification on an anode material, which includes a process of activating the anode material by charging and discharging the battery at least once, using the fluorine-containing separator as a battery separator.
In another aspect, the invention provides a negative electrode interface modification material obtained by the above method.
In yet another aspect, the present invention provides a battery obtained by the above method.
The technical scheme has the following advantages or beneficial effects:
the invention provides a fluorine-containing diaphragm and a battery, wherein the fluorine-containing diaphragm is prepared by coating fluorine-containing slurry on a substrate material, and is used as a diaphragm material to prepare a negative electrode interface modification material of the battery in a lithium battery through at least one charge and discharge process. According to the invention, the fluorine-containing substance is introduced to perform surface modification on the polymer diaphragm, and the in-situ controllable growth of LiF is combined, so that a stable SEI interface layer is constructed in situ, the stability of a cathode/electrolyte interface is improved, and the cycle life of the battery is prolonged. Experimental data show that the specific capacity of the silicon-based negative electrode of the silicon-based lithium ion secondary battery prepared by the method can be improved by 100mAh/g under the current density of C/5, the silicon-based negative electrode can be stably circulated for 100 circles, and the loss of active lithium is effectively reduced. The lithium metal secondary battery prepared by the method is at 1mA/cm 2 Current density of 1mAh/cm 2 Under the deposition amount, the coulomb efficiency can still reach about 98% after 200 cycles of circulation, and the method has better circulation stability. The fluorine-containing diaphragm provided by the invention uses a common diaphragm as a substrateThe fluorine-containing slurry is coated on the substrate, the preparation method is simple and easy to operate, and the prepared cathode interface modification material has uniform appearance and controllable microstructure, and has wide application prospects in the aspects of energy storage, catalysis, adsorption and the like.
Drawings
Fig. 1 is a scanning electron microscope image of an AgF-PP separator prepared in example 1 of the present invention, in which fig. 1a is a scanning electron microscope image of the AgF-PP separator, and fig. 1b is a scanning electron microscope image of a cross section of the AgF-PP separator.
Fig. 2 is a contact angle comparison graph of AgF-PP separator prepared according to example 1 of the present invention.
FIG. 3 is a comparative X-ray diffraction pattern of AgF-PP separator made according to example 1 of the invention.
Fig. 4 is a comparison graph of the cycle capacity of the AgF-PP separator prepared in example 1 of the present invention for a silicon-based secondary lithium ion battery.
Fig. 5 is a comparison graph of the cycle capacity of the AgF-PP separator prepared in example 5 of the present invention for a silicon-based secondary lithium ion battery.
Fig. 6 is a structural view of a battery prepared in example 1 of the present invention.
Detailed Description
The following examples are only a part of the present invention, and not all of them. Thus, the detailed description of the embodiments of the present invention provided below is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the invention without making creative efforts, belong to the protection scope of the invention.
In the present invention, all the equipment, materials and the like are commercially available or commonly used in the industry, if not specified. The methods in the following examples are conventional in the art unless otherwise specified.
Example 1
(1) AgF-PP diaphragm:
AgF powder, conductive carbon black and polyvinylidene fluoride (PVDF) are mixed according to the mass ratio of 7: 2: 1, uniformly mixing, wherein the mass of AgF powder is 175mg, adding N-methyl pyrrolidone (NMP) into the mixed powder, and the mass of NMP solvent is 4.2 times of the mass of the mixed powder; stirring for 4 hours by using a magnetic stirrer to obtain uniform slurry; uniformly coating the slurry on a PP diaphragm by using a four-side preparation device, wherein the coating thickness is 5 mu m; carrying out vacuum heat preservation on the coated AgF-PP diaphragm in a transition cabin of a glove box at 50 ℃ for 12h for drying; the thickness of the dried AgF-PP diaphragm coating layer is 2 mu m, and the AgF-PP diaphragm coating layer is cut into a wafer with the diameter of 16mm by a punch; the processes are all carried out in a glove box;
(2) SiO pole piece:
SiO powder, conductive carbon black and a LiPAA binder are mixed according to the mass ratio of 8: 1: 1, uniformly mixing, wherein the mass of the used SiO powder is 200 mg; adding deionized water into the mixed slurry, wherein the mass of a deionized water solvent is 1-1.12 times of the mass of the mixed slurry; stirring for 4 hours by using a magnetic stirrer to obtain uniform slurry; uniformly coating the slurry on a copper sheet by using a four-side preparation device; preserving the heat of the coated copper sheet in a drying oven at 75 ℃ for 12 h; cutting the electrode plate into a SiO electrode plate with the diameter of 12mm by using a cutting machine;
(3) assembling the battery:
lithium sheet as counter electrode, 1M LiPF 6 (solvent: Ethylene Carbonate (EC): diethyl carbonate (DEC): fluoroethylene carbonate (FEC) in a volume ratio of 3: 6: 1) as an electrolyte, a porous single-layer polypropylene film (polypropylene) as a general separator, in a glove box (high-purity argon atmosphere, wherein O is present 2 And H 2 O content is less than 0.1ppm) and a button cell packaging machine is adopted to assemble a 2032 type button cell. As shown in fig. 6, the sequential order of cell assembly is: the lithium battery comprises a negative electrode shell, a lithium sheet, electrolyte, a common diaphragm, electrolyte, an AgF-PP diaphragm, electrolyte, a SiO pole piece, a gasket, an elastic sheet and a positive electrode shell, wherein the total amount of the electrolyte is 70 mu L.
And (3) carrying out first charge-discharge activation on the assembled battery, wherein the first charge rate is C/20, and the first discharge rate is C/20.
The SEM image of the AgF-PP separator prepared in this example is shown in fig. 1, where fig. 1 shows: the AgF coating on the surface of the diaphragm is uniform and stable in appearance.
The contact angle of the AgF-PP separator prepared in this example and the contact angle of the PP separator are shown in fig. 2, and fig. 2 shows: the AgF coating on the surface of the separator (figure 2b) has a lower contact angle relative to the PP separator (figure 2a), which indicates that the separator has better electrolyte wettability.
The XRD of the AgF-PP separator prepared in this example and the XRD pattern of the AgF-PP separator after the first discharge are shown in fig. 3, and fig. 3 shows: the surface of the prepared AgF separator was a uniform composition AgF coating (fig. 3a), and after the first discharge, the coating surface was Ag (fig. 3b), indicating that the substitution reaction AgF + Li ═ Ag + LiF was successful.
The cycle capacity plots for the AgF-PP separator and PP separator prepared in this example are shown in fig. 4, where fig. 4 shows: the discharge specific capacity of SiO is improved by 10 percent, and the specific capacity can still reach 1118.3mAh/g after 100-circle long cycle test under the current density of C/5. The cell structure prepared in this example is shown in fig. 6: the AgF-PP diaphragm is provided with an interface modification layer on the surface of the cathode material through a displacement reaction in the first charge-discharge process, and the interface layer is rich in inorganic LiF, so that the interface layer is stabilized, and therefore, the battery provided by the invention can effectively reduce the loss of active lithium and shows good cycling stability.
Example 2
(1) AgF-PP diaphragm:
AgF powder, conductive carbon black and PVDF are mixed according to the mass ratio of 7: 2: 1, after uniformly mixing, the mass of the AgF powder is 175 mg; adding NMP into the mixed powder, wherein the mass of the NMP solvent is 4.2 times of that of the mixed powder; stirring for 4 hours by using a magnetic stirrer to obtain uniform slurry; uniformly coating the slurry on a PP diaphragm by using a four-side preparation device, wherein the coating thickness is 5 mu m; preserving the heat of the coated AgF-PP diaphragm for 12 hours at 50 ℃ in a transition cabin of a glove box; the thickness of the dried AgF-PP diaphragm coating layer is 2 mu m, and the dried AgF-PP diaphragm is cut into a wafer with the diameter of 16mm by a punch; the processes are all carried out in a glove box;
(2) copper pole piece:
cutting the copper sheet into electrode plates with the diameter of 12mm by using a cutting machine;
(3) assembling the battery:
using lithium sheet asFor the counter electrode, LiTFSI (solvent: 1, 3-Dioxolane (DOL): ethylene glycol dimethyl ether (DME) was used in a volume ratio of 1: 1, 2 wt.% LiNO 3 As additive) as electrolyte, a porous single-layer polypropylene film (polypropylene) as a common separator, in a glove box (high-purity argon atmosphere, where O is present 2 And H 2 O content is less than 0.1ppm) assembling a 2032 type button cell by a button cell packaging machine; the battery assembly sequence is as follows: the lithium battery comprises a negative electrode shell, a lithium sheet, electrolyte, a common diaphragm, electrolyte, an AgF-PP diaphragm, electrolyte, a copper electrode sheet, a gasket, an elastic sheet and a positive electrode shell; the total amount of electrolyte was 70. mu.L.
The electrochemical test of the assembled battery shows that the current density of the first charge-discharge activation is 0.1mA/cm 2 The deposition amount is 1mAh/cm 2 . After circulating for 2 circles under the condition, the current density is changed to 1mA/cm 2 And the deposition amount is not changed, and the circulation is continued. The result shows that the coulombic efficiency can reach 98% after 200-circle long-cycle test, and the good cycle stability is shown.
Example 3
(1)FeF 3 -PP separator
FeF is mixed 3 The powder, the conductive carbon black and the PVDF are mixed according to the mass ratio of 7: 2: 1, after uniformly mixing, the mass of the AgF powder is 175 mg; adding NMP into the mixed powder, wherein the mass of the NMP solvent is 4.2 times of that of the mixed powder; stirring for 4 hours by using a magnetic stirrer to obtain uniform slurry; uniformly coating the slurry on a PP diaphragm by using a four-side preparation device, wherein the coating thickness is 5 mu m; FeF coated well 3 -heat preservation of PP septum in transition chamber of glove box at 50 ℃ for 12 h; the thickness of the dried AgF-PP diaphragm coating layer is 2 mu m, and the dried FeF 3 -cutting the PP separator into discs with a diameter of 16mm using a punch; the processes are all carried out in a glove box;
(2) copper pole piece:
cutting the copper sheet in the initial state into electrode plates with the diameter of 12mm by using a cutting machine;
(3) assembling the battery:
lithium sheet is used as a counter electrode, and the volume ratio of 1M LiTFSI (solvent: 1, 3-Dioxolane (DOL): ethylene glycol dimethyl ether (DME) is as follows1：1，2wt.％LiNO 3 As additive) as electrolyte, a porous single-layer polypropylene film (polypropylene) as a common separator, in a glove box (high-purity argon atmosphere, where O is present 2 And H 2 O content is less than 0.1ppm) assembling a 2032 type button cell by a button cell packaging machine; the battery assembly sequence is as follows: the lithium battery comprises a negative electrode shell, a lithium sheet, electrolyte, a common diaphragm, electrolyte, an AgF-PP diaphragm, electrolyte, a copper electrode sheet, a gasket, an elastic sheet and a positive electrode shell; the total amount of electrolyte was 70. mu.L.
The electrochemical test of the assembled battery shows that the current density of the first charge-discharge activation is 0.1mA/cm 2 The deposition amount is 1mAh/cm 2 . After circulating for 2 circles under the condition, the current density is changed to 1mA/cm 2 And the deposition amount is not changed, and the circulation is continued. The result shows that the coulombic efficiency can reach 98% after 165-circle long cycle test, and the good cycle stability is shown.
Example 4
(1) AgF-PP diaphragm:
AgF powder, conductive carbon black and polyvinylidene fluoride (PVDF) are mixed according to the mass ratio of 8: 1: 1, uniformly mixing, wherein the mass of the AgF powder is 200 mg; adding NMP into the mixed powder, wherein the mass of the NMP solvent is 4.2 times of that of the mixed powder; stirring for 4 hours by using a magnetic stirrer to obtain uniform slurry; uniformly coating the slurry on a PP (polypropylene) diaphragm by using a four-side preparation device, wherein the coating thickness is 5 mu m; carrying out vacuum heat preservation on the coated AgF-PP diaphragm in a transition cabin of a glove box at 50 ℃ for 12h for drying; cutting the dried AgF-PP diaphragm coating layer into a wafer with the diameter of 16mm by using a punch, wherein the thickness of the AgF-PP diaphragm coating layer is 2 mu m; the processes are all carried out in a glove box;
(2) SiO pole piece:
SiO powder, conductive carbon black and a LiPAA binder are mixed according to the mass ratio of 8: 1: 1, uniformly mixing, wherein the mass of the used SiO powder is 200 mg; adding deionized water into the mixed slurry, wherein the mass of the deionized water is 1-1.12 times of that of the mixed slurry; stirring for 4 hours by using a magnetic stirrer to obtain uniform slurry; uniformly coating the slurry on a copper sheet by using a four-side preparation device; preserving the heat of the coated copper sheet in a drying oven at 75 ℃ for 12 h; cutting the electrode plate into electrode plates with the diameter of 12mm by using a cutting machine;
(3) assembling the battery:
lithium sheet as counter electrode, 1M LiPF 6 (solvent: Ethylene Carbonate (EC): diethyl carbonate (DEC): fluoroethylene carbonate (FEC) in a volume ratio of 3: 6: 1) as an electrolyte, a porous single-layer polypropylene film (polypropylene) as a general separator, in a glove box (high-purity argon atmosphere, wherein O is present 2 And H 2 O content is less than 0.1ppm) and a button cell packaging machine is adopted to assemble a 2032 type button cell. As shown in fig. 6, the sequential order of cell assembly is: the lithium battery comprises a negative electrode shell, a lithium sheet, electrolyte, a common diaphragm, electrolyte, an AgF-PP diaphragm, electrolyte, a SiO pole piece, a gasket, an elastic sheet and a positive electrode shell, wherein the total amount of the electrolyte is 70 mu L.
The assembled battery is subjected to charge-discharge electrochemical test, the first charge rate is C/20, the first discharge rate is C/20, and the specific capacity of SiO is improved to a certain extent after 100-circle long-cycle test under the current density of C/5.
Example 5
(1) AgF-PP diaphragm:
AgF powder, conductive carbon black and polyvinylidene fluoride (PVDF) are mixed according to the mass ratio of 7: 2: 1, uniformly mixing, wherein the mass of AgF powder is 175mg, and adding NMP into the mixed powder, wherein the mass of the NMP solvent is 4.2 times of that of the mixed powder; stirring for 4 hours by using a magnetic stirrer to obtain uniform slurry; uniformly coating the slurry on a PP diaphragm by using a four-side preparation device, wherein the coating thickness is 100 mu m; carrying out vacuum heat preservation on the coated AgF-PP diaphragm in a transition cabin of a glove box at 50 ℃ for 12h for drying; cutting into 16mm diameter circular slice with punch; the processes are all carried out in a glove box;
(2) SiO pole piece:
SiO powder, conductive carbon black and a LiPAA binder are mixed according to the mass ratio of 8: 1: 1, uniformly mixing, wherein the mass of the used SiO powder is 200 mg; adding deionized water into the mixed slurry, wherein the mass of a deionized water solvent is 1-1.12 times of the mass of the mixed slurry; stirring for 4 hours by using a magnetic stirrer to obtain uniform slurry; uniformly coating the slurry on a copper sheet by using a four-side preparation device; preserving the heat of the coated copper sheet in a drying oven at 75 ℃ for 12 h; cutting the electrode plate into a SiO electrode plate with the diameter of 12mm by using a cutting machine;
(3) assembling the battery:
lithium sheet as counter electrode, 1M LiPF 6 (solvent: Ethylene Carbonate (EC): diethyl carbonate (DEC): fluoroethylene carbonate (FEC) in a volume ratio of 3: 6: 1) as an electrolyte, a porous single-layer polypropylene film (polypropylene) as a general separator, in a glove box (high-purity argon atmosphere, wherein O is present 2 And H 2 O content is less than 0.1ppm) and a button cell packaging machine is adopted to assemble a 2032 type button cell. As shown in fig. 6, the sequential order of cell assembly is: the lithium battery comprises a negative electrode shell, a lithium sheet, electrolyte, a common diaphragm, electrolyte, an AgF-PP diaphragm, electrolyte, a SiO pole piece, a gasket, an elastic sheet and a positive electrode shell, wherein the total amount of the electrolyte is 70 mu L.
And (3) carrying out first charge-discharge activation on the assembled battery, wherein the first charge rate is C/20, and the first discharge rate is C/20.
The cycle capacity plots for the AgF-PP separator and PP separator prepared in this example are shown in fig. 5, fig. 5 showing: under the current density of C/5, the specific capacity of SiO is averagely improved by 10 percent, the specific capacity of SiO is averagely improved by 100mAh/g, and the specific capacity can still reach 1102.7mAh/g after 100-circle long-cycle test.
The above description is only of the preferred embodiments of the present invention, and it should be noted that: it will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the principles of the invention and these are intended to be within the scope of the invention.
Claims (10)
1. The fluorine-containing diaphragm is characterized in that the fluorine-containing diaphragm is obtained by coating fluorine-containing slurry on a substrate and drying; the fluorine-containing slurry comprises fluorine-containing powder, a conductive agent, a binder and N-methyl pyrrolidone.
2. The fluorine-containing separator according to claim 1, wherein the fluorine-containing powder is at least one selected from the group consisting of silver fluoride powder, iron fluoride powder, magnesium fluoride powder, aluminum fluoride powder, zinc fluoride powder, and antimony fluoride powder, and more preferably silver fluoride powder;
preferably, the conductive agent is selected from at least one of conductive carbon black and acetylene black, and is further preferably conductive carbon black;
preferably, the binder is polyvinylidene fluoride;
preferably, the substrate is a PP separator or a PE separator, and more preferably a PP separator.
3. The fluorine-containing membrane according to claim 1, wherein the fluorine-containing slurry contains 50 to 90 parts by mass of the fluorine-containing powder, and more preferably 70 parts by mass of the fluorine-containing powder; the conductive agent is 5-25 parts by weight, and preferably 20 parts by weight; the mass portion of the binder is 5-25, and the preferable mass portion is 10;
preferably, the mass of the N-methyl pyrrolidone is 4.1-4.5 times of the total mass of the fluorine-containing powder, the conductive agent and the binder.
4. The fluorine-containing membrane according to claim 1, wherein the drying is performed at 50-60 ℃ for 10-12 h;
preferably, the thickness of the coating is 2 to 100 μm.
5. Use of a fluorine-containing separator as claimed in any one of claims 1 to 4 for the manufacture of a battery;
preferably, the battery is a silicon-based secondary lithium ion battery or a lithium metal secondary battery;
preferably, the electrolyte of the battery is selected from ester-based or ether-based electrolytes.
6. A method for performing interface modification on a negative electrode material, which is characterized by comprising the step of activating the negative electrode material by charging and discharging a battery at least once by using the fluorine-containing diaphragm as a battery diaphragm according to any one of claims 1 to 4.
7. The method of claim 6, wherein the electrolyte of the battery is selected from an ester-based or ether-based electrolyte.
8. The method of claim 6, wherein the battery is a silicon-based secondary lithium ion battery or a lithium metal secondary battery.
9. A negative electrode interface modification material obtainable by the method of any one of claims 6 to 8.
10. A battery obtained by the method of any one of claims 6 to 8.
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