CN110323493B - Combined sheet of positive pole piece and polymer electrolyte membrane and preparation method thereof - Google Patents
Combined sheet of positive pole piece and polymer electrolyte membrane and preparation method thereof Download PDFInfo
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- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0561—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of inorganic materials only
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- 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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Abstract
The invention provides a preparation method of a combined sheet of a positive pole piece and a polymer electrolyte membrane, which comprises the following steps: (1) carrying out ball milling treatment on the positive active material and the ceramic-based solid electrolyte; (2) under heating, dissolving a polymer binder in an organic solvent, adding a lithium salt, and stirring to completely dissolve the lithium salt; (3) adding the solution obtained in the step (2) into a ceramic-based solid electrolyte, stirring, pouring into a mold, and evaporating the solvent to prepare a polymer electrolyte membrane; (4) adding the positive active material and the conductive additive in the step (1) into the solution prepared in the step (2), stirring, coating the solution on an aluminum foil, and drying to prepare a positive pole piece; (5) and (4) tabletting the positive pole piece, combining the tabletting with the polymer electrolyte membrane in the step (3), tabletting, and carrying out melting treatment to obtain a combined piece. The method can improve the compatibility of the positive plate and the electrolyte membrane, increase the solid-solid interface contact of the solid-state battery and reduce the impedance; effectively improves the coulombic efficiency of the battery and fully exerts the advantages of the electrode material.
Description
Technical Field
The invention relates to the field of lithium ion batteries, in particular to a preparation method and application of a positive electrode material pole piece of a solid-state battery.
Background
Lithium ion batteries are the most energy intensive electrochemical energy storage systems that have been used. With the application of lithium ion batteries in power automobiles, large-scale energy storage and the like, the market puts higher requirements on energy density and safety performance of the lithium ion batteries.
From the energy density perspective, the capacity of a graphite cathode in the existing lithium ion battery cathode material can reach more than 300mAhg < -1 >, and a silicon-carbon composite cathode with higher capacity is also applied to a small range; the positive electrode material is difficult to break through 200mAhg < -1 >, and becomes a main factor for limiting the improvement of the energy density of the lithium ion battery. Starting from the constitution of lithium ion batteries, the positive electrode material accounts for a large proportion, which is about 3 to 4 times of the negative electrode material.
Therefore, the performance of the anode material directly influences the performance of the battery, and the development of the anode material of the lithium ion battery with higher energy density is a necessary way for the development of the lithium ion battery.
Currently, many researches are made on high-voltage lithium cobaltate, high-voltage spinel phase, lithium-rich manganese-based material, high-nickel ternary system and the like. Besides the performance of the anode material, the excellent preparation method of the anode plate is one of the exploration directions of battery manufacturers.
In addition, with the high demand of the market for lithium ion batteries, all-solid-state lithium metal batteries are receiving wide attention due to their high specific energy and high safety performance. However, at present, all-solid-state batteries face very severe tests, including excessive interface impedance, difficulty in implementing fast charge on the solid-state batteries, immature preparation process, high cost, and the like.
The solid-solid interface problem is the highest of the current importance, and the interface between the solid electrolyte and the electrode material is in a solid-solid state, so that the effective contact between the electrode and the electrolyte is weaker, the transmission kinetics of ions in a solid substance is slower, and the quick charge is difficult to realize; in addition, the current solid-state battery has large internal resistance, and can cause irreversible energy loss in the charging process; the solid-state battery has the disadvantages of immature preparation process, high cost and the like.
For the reasons, the inventor improves the prior art and researches a positive electrode material pole piece of a solid-state battery and a preparation method and application thereof.
Disclosure of Invention
In order to solve the above problems, the present inventors have conducted intensive studies and, as a result, have found that: the polymer electrolyte matrix is used as a binder, and the problems of insufficient solid-solid interface contact and overlarge impedance in the solid-state battery can be solved to a certain extent by the high-temperature melting treatment process of the positive plate and the solid electrolyte; in addition, the addition of lithium salt can also effectively improve the coulombic efficiency of the battery, and give full play to the advantages of the electrode material, thereby completing the invention.
The object of the present invention is to provide the following:
in a first aspect, the present invention provides a method for preparing a composite sheet of a positive electrode sheet and a polymer electrolyte membrane, the method comprising:
performing ball milling treatment on a positive active material and a ceramic-based solid electrolyte to coat the surface of the positive active material with the ceramic-based solid electrolyte;
under the heating of the step (2), dissolving the polymer binder in an organic solvent, adding lithium salt, and stirring to completely dissolve the lithium salt;
step (3), adding the solution prepared in the step (2) into a ceramic-based solid electrolyte, uniformly stirring, pouring into a mold, and evaporating the solvent to prepare a polymer electrolyte membrane;
step (4), adding the solution prepared in the step (2) into the positive active substance coated with the ceramic-based solid electrolyte prepared in the step (1) and a conductive additive, stirring into slurry, coating the slurry on an aluminum foil, and drying to prepare a positive pole piece;
and (5) tabletting the positive pole piece prepared in the step (4), combining the tabletting with the polymer electrolyte membrane prepared in the step (3), tabletting again, and carrying out melting treatment to obtain the combined piece of the positive pole piece and the polymer electrolyte membrane.
The invention also provides a combined sheet of the positive pole piece and the polymer electrolyte membrane, which is prepared by the method and can be used as the positive pole piece and the electrolyte membrane for a solid-state battery.
According to the composite sheet of the positive pole piece and the polymer electrolyte membrane and the preparation method thereof provided by the invention, the following beneficial effects are achieved:
(1) the polymer electrolyte is used as a binder, and the problems of insufficient solid-solid interface contact and overlarge impedance in the solid-state battery can be solved to a certain extent by the process of carrying out high-temperature melting treatment on the positive plate and the solid-state electrolyte;
(2) the coating of the ceramic-based solid electrolyte in the positive plate is beneficial to improving the electrochemical performance of the positive material and improving the compatibility between the positive electrode and the solid electrolyte plate; in addition, the addition of the lithium salt can also effectively improve the coulombic efficiency of the battery and fully exert the advantages of the electrode material.
Drawings
FIG. 1 shows an AC impedance spectrum of a polymer electrolyte membrane prepared in example 1;
fig. 2 is a graph showing the ion conductivity of the polymer electrolyte membrane prepared in example 1;
FIG. 3 is a graph showing an electrochemical window of a polymer electrolyte membrane manufactured in example 1;
FIG. 4 shows a charge and discharge test pattern for the LFP/PEO-LiTFSI/Li solid-state battery prepared in example 1;
FIG. 5 shows a charge and discharge test map of the LCO/PAN-LiTFSI/Li solid-state battery prepared in example 2;
fig. 6 shows an SEM electron micrograph of LATP-coated lithium cobaltate in example 2.
Detailed Description
The features and advantages of the present invention will become more apparent and appreciated from the following detailed description of the invention.
The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. While the various aspects of the embodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated.
In the description of the present invention, it should be noted that the terms "first", "second", "third" and "fourth" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
The present invention is described in detail below.
The invention provides a preparation method of a combined sheet of a positive pole piece and a polymer electrolyte membrane, which comprises the following steps:
performing high-energy ball milling on the positive active material and the ceramic-based solid electrolyte to coat the surface of the positive active material with the ceramic-based solid electrolyte for later use;
preferably, the positive active material is selected from one or more of Lithium Cobaltate (LCO), lithium iron phosphate (LFP), ternary positive electrode (NCM/NCA), Lithium Manganate (LMO), lithium nickel manganese spinel (LNMO) and lithium manganese rich group; preferably lithium iron phosphate or lithium cobaltate;
preferably, the ceramic-based solid electrolyte is one or more of Lithium Aluminum Titanium Phosphate (LATP), lithium aluminum germanium phosphate (lag), Lithium Lanthanum Zirconium Oxide (LLZO), preferably LATP or LLZO;
the mass ratio of the positive electrode active material to the ceramic-based solid electrolyte is 100: (20-0.1), preferably 100: (5-0.5), more preferably 100: (2.5-0.5), e.g., 100:2, 100: 1.
The rotating speed of the high-energy ball mill is 200-400r/h, preferably 350 r/h; the ball milling treatment is carried out for 5 to 10 hours, preferably 5 to 8 hours.
Through ball milling, the particle size of the positive active material and the ceramic-based solid electrolyte can be further reduced, and the specific surface area is remarkably improved; meanwhile, the surface of the anode active material can be uniformly coated with a layer of solid electrolyte membrane, which is beneficial to improving the electrochemical performance of the anode and improving the compatibility with an electrolyte sheet.
Step (2), under heating, dissolving the polymer binder in an organic solvent, slowly adding lithium salt, and stirring to completely dissolve the lithium salt;
preferably, the polymeric binder is one or more of polyethylene oxide (PEO), polyvinylidene fluoride (PVDF-HFP), Polyacrylonitrile (PAN), or polymethyl methacrylate (PMMA).
More preferably, the polymeric binder is PEO having a molecular weight of 10 to 100 million or PAN having a molecular weight of 2.5 to 20 million.
The organic solvent is one or more of Dimethylformamide (DMF), dimethyl sulfoxide (DMSO), tetrahydrofuran or isopropyl acetate, and dimethylformamide or dimethyl sulfoxide is preferably used as the solvent.
Preferably the concentration of the polymeric binder in the organic solvent is from 0.1 to 10g/ml, more preferably from 0.15 to 5g/ml, most preferably from 0.16 to 2g/ml, for example 0.2g/ml, 0.5g/ml, 1g/ml or 1.5 g/ml.
Lithium in the electrode material causes irreversible loss of lithium when the battery is charged and discharged for the first time, and the loss of lithium can be reduced by adding lithium salt into the organic solution.
Preferably, the lithium salt added to the organic solution is lithium hexafluorophosphate (LiPF) 6 ) Lithium perchlorate (LiClO) 4 ) Lithium bis (trifluoromethanesulfonylimide) (LiTFSI), lithium bis (fluorosulfonylimide) (LiFSI), sulfuric acidLithium (Li) 2 SO 4 ) Lithium iodide (LiI) or lithium nitrate (LiNO) 3 ) Preferably, it is LiTFSI or LiClO 4 。
Preferably, the molar ratio of the polymer monomer in the polymer binder to the Li ions in the lithium salt is (10-20):1, more preferably (12-18): 1, e.g., 12:1, 16: 1.
Lithium in the electrode material can cause irreversible loss of lithium when the battery is charged and discharged for the first time, and by adding the lithium salt, the reduction of the irreversible loss of the lithium on the coulombic efficiency of the battery can be reduced and eliminated, the coulombic efficiency of the battery can be effectively improved, and the advantages of the electrode material are fully exerted.
Step (3), adding the solution obtained in the step (2) into a ceramic-based solid electrolyte, uniformly stirring, pouring into a mold, and evaporating the solvent to obtain a polymer electrolyte membrane;
preferably, the ratio (g: ml) of the amount of the ceramic based solid electrolyte to the amount of the solution prepared in the step (2) of taking out is 0.05% to 1%, preferably 0.05% to 0.5%, more preferably 0.1% to 0.3%, for example 0.2%.
Wherein the particle size of the ceramic-based solid electrolyte is 200nm-5 μm; preferably 200nm to 1 μm.
And uniformly stirring the ceramic-based solid electrolyte in the solution to obtain the slurry of the polymer electrolyte membrane.
The polymer binder mainly plays a role of a plasticizer, so that the plasticity of the ceramic-based solid electrolyte membrane is improved; in addition, the polymer binder can improve the ionic conductivity and lithium ion mobility of the ceramic-based solid electrolyte membrane.
The polymer electrolyte membrane is preferably prepared using a mold having a reservoir of a set volume and shape that can hold a set volume of solution or slurry.
Preferably, the slurry for preparing the polymer electrolyte membrane is poured into a mold, and then the solvent in the slurry is evaporated to dryness, so as to obtain the solid polymer electrolyte membrane.
The mold is not limited as long as it accommodates a set volume of liquid and can withstand the high temperatures at which the solvent is evaporated.
Preferably, the solvent in the mold is evaporated to dryness using a heating method to prepare a solid polymer electrolyte membrane. For example, the mold containing the polymer electrolyte membrane slurry is placed in an oven, and the solvent content is reduced by heating to evaporate the solvent until the solvent is substantially evaporated, or the drying may be performed using a vacuum oven.
More preferably, the solvent is heated to 50-60 ℃ during the evaporation process, so that the solvent can be quickly evaporated.
Step (4), adding the solution prepared in the step (2) into the positive electrode active substance coated with the solid electrolyte membrane and the conductive additive prepared in the step (1), stirring into slurry, coating the slurry on an aluminum foil, and drying to prepare a positive electrode plate;
wherein the conductive additive is selected from one or more of carbon black, ketjen black, graphite oxide, graphene, carbon nanotubes and vapor deposited carbon fibers; preferably carbon black or graphite.
Further, the mass ratio of the positive electrode active material to the conductive additive is (20-1): 1; preferably (15-1):1, more preferably (10-2):1, e.g., 8:1, 3.5:1, 2: 1.
The mixing method of the positive electrode active material and the conductive additive is not further limited, and any mixing method in the prior art can be used, such as grinding mixing, sieving mixing, stirring mixing and the like, preferably grinding mixing is used, so that the positive electrode active material and the conductive additive can be crushed while mixing, the particle size of the positive electrode active material and the conductive additive is reduced, the mixing uniformity is improved, and the improvement of the electrical properties are facilitated.
And (3) adding the mixture of the ground positive electrode active substance and the ground conductive additive into the solution prepared in the step (2) and uniformly mixing.
The using ratio (g/ml) of the mixture of the positive electrode active material and the conductive additive to the solution prepared in the step (2) is (5-1): 1, preferably (3-1): 1, e.g., 9:5, 2: 1.
Further, in step 4, the mass ratio of the positive electrode active material to the polymer binder is (25-5):1, preferably (15-5):1, more preferably (10-5): 1, e.g. 8:1, 7:1, 6: 1.
Adding a positive active substance and a conductive additive into the solution taken out in the step (2), uniformly stirring to obtain slurry of the positive pole piece, coating one side of the slurry of the positive pole piece on an aluminum foil, and preferably, the coating density of the slurry of the positive pole piece is 50-300mg/cm 2 More preferably 150-250mg/cm 2 。
And drying the aluminum foil coated with the positive pole piece slurry for 6-12h at 50-80 ℃, preferably drying in a vacuum oven to obtain the positive pole piece.
And (5) tabletting the positive pole piece prepared in the step (4), combining the tabletting with the polymer electrolyte membrane prepared in the step (3), tabletting again, and carrying out melting treatment to obtain the combined piece of the positive pole piece and the solid electrolyte.
In order to increase the solid-solid interface contact between the positive electrode plate prepared in the step (4) and the polymer electrolyte membrane prepared in the step (3), the positive electrode plate and the polymer electrolyte membrane are preferably subjected to tabletting treatment and melting treatment, so that the solid-solid interface contact between the positive electrode plate and the polymer electrolyte membrane is more sufficient.
Preferably, firstly, tabletting the positive pole piece prepared in the step (4), and controlling the pressure to be between 1 and 10 Mpa; through tabletting, the distance between the positive active material and the conductive additive in the positive pole piece is reduced, and the conductivity is improved; meanwhile, the surface of the positive pole piece is smoother, and good contact with the polymer electrolyte membrane is facilitated.
And (4) combining the pressed positive pole piece with the polymer electrolyte membrane prepared in the step (3), and pressing again, wherein the pressure is controlled to be between 1 and 10 Mpa. The positive pole piece and the polymer electrolyte membrane are combined to be pressed into a sheet, so that the problem of insufficient solid-solid interface contact between the positive pole piece and the polymer electrolyte membrane is solved under the action of pressure, and the effective contact of the interface is improved.
Furthermore, the positive pole piece and the polymer electrolyte membrane are subjected to melting treatment, and through the heating melting treatment, the polymer binder in the positive pole piece and the polymer binder in the polymer electrolyte membrane can be fully fused, so that the deep contact of a solid-solid interface is increased. In addition, because the polymer binder in the positive pole piece and the polymer electrolyte membrane is the same material, the polymer binder in the positive pole piece and the polymer binder in the polymer electrolyte membrane are more easily bonded and connected after being heated, melted and deformed during melting treatment, so that the contact area between the positive pole piece and the polymer electrolyte membrane is increased, the solid-solid interface contact is improved, and the interface impedance is reduced.
The temperature of the melting treatment of the positive pole piece and the polymer electrolyte membrane is preferably 45-85 ℃, more preferably 55-75 ℃, such as 60 ℃;
the time for the melting treatment of the positive pole piece and the polymer electrolyte membrane is 2-4h, such as 3 h.
The polymer electrolyte matrix is used as a binder, and the problems of insufficient solid-solid interface contact and overlarge impedance in the solid-state battery can be solved to a certain extent by the process of carrying out high-temperature melting treatment on the positive plate and the solid electrolyte.
In addition, the invention also provides a combined sheet of the positive pole piece and the polymer electrolyte membrane prepared by the method, and the combined sheet can be used as the positive pole piece and the electrolyte membrane for a solid-state battery.
The combined sheet has good charging and discharging performance and high coulombic efficiency.
Examples
Example 1
Lithium iron phosphate (LFP) and Lithium Aluminum Titanium Phosphate (LATP) were mixed in a ratio of 100:1, and performing ball milling for 6 hours at a ball milling rotating speed of 350 revolutions per hour to prepare the lithium iron phosphate coated with the LATP on the surface.
Weighing 5g of PEO with the molecular weight of 60 ten thousand, uniformly dispersing in 25ml of DMF solvent under heating, slowly adding LiTFSI after the solution is clarified, and stirring until the solution is completely dissolved. Wherein the molar ratio of monomer in PEO to lithium in LiTFSI is 16: 1.
and (3) taking 20ml of the solution, adding 0.02g of LATP into the solution, directly pouring the solution on a Polytetrafluoroethylene (PTFE) mould after uniformly stirring, and evaporating the solvent in a 50-degree oven to prepare the polymer electrolyte membrane.
Meanwhile, 8g of lithium iron phosphate coated with LATP and 1g of carbon black are added into the rest DMF solution, the mixture is continuously stirred into uniform slurry, the uniform slurry is uniformly coated on one side of an Al foil, and the Al foil is dried in a vacuum oven at 80 ℃ to prepare the lithium iron phosphate electrode plate.
And tabletting the lithium iron phosphate electrode slice under the condition of 8 MPa. And (3) combining the lithium iron phosphate electrode slice subjected to tabletting treatment with the polymer electrolyte membrane, and then tabletting again under the tabletting condition of 8 MPa.
And (3) placing the combined sheet of the polymer electrolyte membrane and the lithium iron phosphate electrode sheet in a 60-degree oven for melting treatment for 2 hours, and naturally cooling to room temperature (20-25 degrees) to obtain the LFP/PEO electrode sheet.
And directly matching the LFP/PEO pole piece with the metal lithium to assemble the LFP/PEO-LiTFSI/Li solid-state battery, and placing the battery in a 70-DEG oven to be stable for 4 hours for testing.
Example 2
Lithium Cobaltate (LCO) and Lithium Aluminum Titanium Phosphate (LATP) were mixed according to a 100:1, and performing ball milling for 6 hours at a ball milling rotating speed of 350 revolutions per hour to prepare the lithium cobaltate with the surface coated with the LATP.
Weighing 5g of PAN with the molecular weight of 15 ten thousand, uniformly dispersing in 25ml of DMF solvent under heating, slowly adding LiTFSI after the solution is clarified, and stirring until the LiTFSI is completely dissolved to prepare the PAN-LiTFSI polymer electrolyte. Wherein the molar ratio of the monomers in the PAN to the lithium in the LiTFSI is 12: 1.
taking 20ml of the solution, adding 0.04g of LATP into the solution, directly pouring the solution on a Polytetrafluoroethylene (PTFE) grinding tool after uniformly stirring, and evaporating the solvent at 50 ℃ to prepare the polymer electrolyte membrane.
Meanwhile, 6g of lithium cobaltate with the surface coated with LATP and 3g of carbon black are added into the rest polymer electrolyte solution, the mixture is continuously stirred into uniform slurry, the uniform slurry is uniformly coated on an Al foil on one side, and the uniform slurry is dried in an 80-DEG oven for later use, so that the lithium cobaltate electrode slice is prepared.
And tabletting with a lithium cobaltate electrode plate, wherein the condition of tabletting is 8 Mpa. And (3) combining the lithium cobaltate electrode slice subjected to tabletting treatment with the polymer electrolyte membrane, and then tabletting again under the tabletting condition of 8 MPa.
And (3) placing the combined sheet of the polymer electrolyte membrane and the lithium cobaltate electrode plate in a 60-DEG C oven for melting treatment for 2 hours, and naturally cooling to room temperature (20-25 ℃) to form an LCO/PAN electrode plate.
And (3) directly matching and assembling the LCO/PAN pole piece and the metal lithium to form the LCO/PAN-LiTFSI/Li solid-state battery, and testing the battery after the battery is placed in a 70-DEG oven and stabilized for 4 hours.
Examples of the experiments
Experimental example 1
The polymer electrolyte membrane prepared in example 1 was measured for ac impedance under the following conditions: 10mHz-4MHz, and a perturbation of 5mV, which were tested for their AC impedances at 30 deg.C, 40 deg.C, 50 deg.C, and 60 deg.C, respectively.
As a result, as shown in fig. 1, it can be seen from fig. 1 that the resistance of the polymer electrolyte becomes smaller as the temperature increases.
Experimental example 2
The polymer electrolyte membrane prepared in example 1 was taken and tested for ionic conductivity under the following test conditions: 10mHz-4MHz, perturbation 5mV
As a result, as shown in FIG. 2, it can be seen from FIG. 2 that the room-temperature ionic conductivity of the prepared polymer electrolyte membrane was 1.45X 10 -4 S/cm 2 And an ionic conductivity of 2.467X 10 at 60 DEG -3 S/cm 2 And the ionic conductivity is close to that of a liquid electrolyte, which shows that the polymer electrolyte membrane has better ionic migration performance.
Experimental example 3
The electrochemical window of the polymer electrolyte membrane prepared in example 1 was measured under the following conditions: 10mHz-4MHz, perturbation 5mV
As shown in fig. 3, it can be seen from fig. 3 that the electrochemical window of the electrolyte can reach above 5V at room temperature, and can still reach 5V at 70 degrees, which is much higher than that of the PEO-based polymer (average about 4.2V) in the prior art, so that the electrolyte can be effectively ensured to have a wider operating voltage, and can be matched with more positive electrode materials, such as high-voltage lithium cobalt oxide and high-voltage spinel phase.
Experimental example 4
The LFP/PEO-LiTFSI/Li solid-state battery prepared in example 1 was subjected to a charge and discharge test, and the voltage range was 2.5-3.8V and the current level was 0.2C.
The test results are shown in FIG. 4, where the first cycle specific charge capacity is 152mAhg -1 First week reversible capacity of 151.5mAhg -1 The coulombic efficiency in the first week is 99.8%, and the circulation retention rate in 20 weeks is 95.65%.
Experimental example 5
The LCO/PAN-LiTFSI/Li solid-state battery prepared in example 2 was subjected to a charge and discharge test, with a voltage range of 3.0-4.2V and a current level of 0.1C.
The test results are shown in FIG. 5, in which the first cycle specific charge capacity was 139.1mAhg -1 First week reversible capacity of 135.2mAhg -1 The first week coulombic efficiency is 97.38%, and the 20-week cycle retention rate reaches 90.02%.
Experimental example 6
When the LATP-coated lithium cobaltate prepared in example 2 is observed by SEM electron microscopy, as shown in fig. 6, after coating with the ceramic-based solid electrolyte, the lithium cobaltate particles have a thicker electrolyte coating layer on the surface, which helps to improve the electrochemical performance of the material.
The invention has been described in detail with reference to specific embodiments and illustrative examples, but the description is not intended to be construed in a limiting sense. Those skilled in the art will appreciate that various equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its embodiments without departing from the spirit and scope of the present invention, which fall within the scope of the present invention. The scope of the invention is defined by the appended claims.
Claims (8)
1. A preparation method of a combined sheet of a positive pole piece and a polymer electrolyte membrane is characterized by comprising the following steps:
performing ball milling treatment on the positive active material and the ceramic-based solid electrolyte to coat the surface of the positive active material with the ceramic-based solid electrolyte;
the anode active material is selected from one or more of lithium cobaltate, lithium iron phosphate, lithium manganate, spinel lithium nickel manganese or lithium-rich manganese base,
the ceramic-based solid electrolyte is one or more of titanium aluminum lithium phosphate, germanium aluminum lithium phosphate and lithium lanthanum zirconium oxide;
the mass ratio of the positive electrode active material to the ceramic-based solid electrolyte is 100: (5-0.5);
step (2), under heating, dissolving the polymer binder in an organic solvent, adding lithium salt, and stirring to completely dissolve the lithium salt;
the lithium salt is bis (trifluoromethane) sulfonyl imide lithium or lithium perchlorate;
the molar use ratio of the polymer monomer in the polymer binder to the Li ions in the lithium salt is (12-18): 1;
step (3), adding the solution prepared in the step (2) into a ceramic-based solid electrolyte, uniformly stirring, pouring into a mold, and evaporating the solvent to prepare a polymer electrolyte membrane;
the dosage ratio of the ceramic-based solid electrolyte to the solution prepared in the step (2) is 0.1-0.3% g/ml;
step (4), adding the solution prepared in the step (2) into the positive active substance coated with the ceramic-based solid electrolyte prepared in the step (1) and a conductive additive, stirring into slurry, coating the slurry on an aluminum foil, and drying to prepare a positive pole piece;
the mass ratio of the positive electrode active substance to the conductive additive is (10-2) to 1;
step (5), after the positive pole piece prepared in the step (4) is pressed into sheets, the sheets are combined with the polymer electrolyte membrane prepared in the step (3), and the sheets are pressed again and subjected to melting treatment to obtain a combined sheet of the positive pole piece and the polymer electrolyte membrane;
during tabletting, the pressure is controlled to be 1-10 Mpa;
the temperature of the melting treatment of the positive pole piece and the polymer electrolyte membrane is 45-85 ℃.
2. The production method according to claim 1, characterized in that, in step (1), the positive electrode active material is lithium cobaltate or lithium iron phosphate;
the ceramic-based solid electrolyte is lithium aluminum titanium phosphate or lithium lanthanum zirconium oxide.
3. The production method according to claim 1, characterized in that, in step (1), the mass ratio of the positive electrode active material to the ceramic-based solid electrolyte is 100: (2.5-0.5).
4. The production method according to claim 1, wherein, in the step (3), the ratio of the amount of the ceramic-based solid electrolyte to the amount of the solution produced in the taking-out step (2) is 0.2% g/ml.
5. The production method according to claim 1, wherein in step (4), the mass ratio of the positive electrode active material to the conductive additive is 8:1, 3.5:1, 2: 1.
6. The production method according to claim 1, characterized in that, in step (4), the amount ratio (g/ml) of the mixture of the positive electrode active material and the conductive additive to the solution produced in step (2) taken out is (5-1): 1.
7. the production method according to claim 1, wherein in the step (4), the ratio of the amount of the mixture of the positive electrode active material and the conductive additive to the amount of the solution produced in the step (2) taken out is (3-1): 1.
8. the production method according to claim 1, wherein in the step (5), the pressure is controlled to be 8 Mpa;
the temperature of the melting treatment of the positive pole piece and the polymer electrolyte membrane is 55-75 ℃;
the time for the melting treatment of the positive pole piece and the polymer electrolyte membrane is 2-4 h.
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| CN110993947A (en) * | 2019-11-25 | 2020-04-10 | 珠海冠宇电池有限公司 | Modified anode material and lithium ion battery |
| CN111129602A (en) * | 2019-12-20 | 2020-05-08 | 中国电子科技集团公司第十八研究所 | Preparation method of integrally-formed solid-state battery |
| CN111342013B (en) * | 2020-03-04 | 2021-12-10 | 深圳市合壹新能技术有限公司 | Preparation method of electrode material, electrode and lithium ion battery |
| CN111710817A (en) * | 2020-06-28 | 2020-09-25 | 昆山宝创新能源科技有限公司 | Solid-state battery and preparation method and application thereof |
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