CN115700939A - Preparation method of composite electrode material and preparation method of lithium battery pole piece - Google Patents
Preparation method of composite electrode material and preparation method of lithium battery pole piece Download PDFInfo
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Abstract
The invention discloses a preparation method of a composite electrode material and a preparation method of a lithium battery pole piece, wherein the composite electrode material is prepared by coating a halide solid electrolyte and a polymer on the electrode material. According to the invention, the ionic conductivity of the electrode material is improved through the halide solid electrolyte, and the problems that the halide solid electrolyte is easy to absorb water, deliquesce and difficult to store are solved through polymer coating, so that the finally obtained composite electrode material has the characteristics of no deliquescence and easy storage, and a lithium battery pole piece prepared by adopting the composite electrode material has excellent ionic conductivity because of containing the halide solid electrolyte coating.
Description
Technical Field
The invention belongs to the field of lithium batteries, and particularly relates to a preparation method of a composite electrode material and a preparation method of a lithium battery pole piece.
Background
With the improvement of the safety requirement of lithium batteries, the application of inorganic solid electrolytes in lithium ion batteries is receiving more and more attention. The scale application of the solid electrolyte not only needs to have excellent electrochemical performance, but also needs to be matched with the scale production process in terms of chemical stability and mechanical processing performance. In the main solid electrolytes, sulfide ions have high conductivity but poor chemical stability; the oxide system is complicated, the machining performance is poor, and the problem of physical contact is difficult to solve; the thermodynamic stability of borohydride, the adaptability between the borohydride and a positive electrode and a negative electrode and the capability of inhibiting the growth of dendrites are insufficient; polymer solid electrolytes require high temperature operation and have poor ion conductivity.
The halide solid electrolyte has high ionic conductivity, stable chemical/electrochemical stability, good plasticity, and ion conductivity at room temperature>10 -3 S·cm -1 The composite material has good thermal and electrochemical stability, has good compatibility with various interfaces, is a few solid electrolyte materials which can be synthesized in batch in a solution, particularly in an aqueous solution, and thus has great potential in the field of lithium ion batteries, particularly lithium battery pole pieces. The halide solid electrolyte is used not only as an electrolyte, but also as a buffer layer between the high-voltage positive electrode and the electrolyte by utilizing its oxidation resistance; and for some electrolytes with better stability of the negative electrode, such as Li 3 OCl and the like also have potential as a protective layer of a negative electrode material; good electrochemical stability makes the halide solid state electrolyte also potentially useful as a coating for high voltage oxide positive electrode material particles. And the characteristic that the coating can be dissolved in solvents such as water and the like ensures that the coating has low difficulty, can be scaled and has good coating effect in coating engineering application.
However, the halide electrolyte has the characteristic of deliquescence, is easy to form crystal water to enable the ionic conductivity to be reduced sharply, and the drying and dehydration temperature of the halide electrolyte is higher than 200 ℃, so that the halide electrolyte conflicts with the temperature tolerance of a binder in the pole piece, and the large-scale engineering application of the material is limited.
In view of the above, there is a need to develop a material combining a halide electrolyte and a lithium battery electrode material and a preparation method thereof, which can improve the ion conduction performance of the composite electrode material and solve the problems of easy deliquescence, difficult storage and application of the halide electrolyte.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a preparation method of a composite electrode material and a preparation method of a lithium battery pole piece, wherein the ionic conductivity of the electrode material is improved through a halide solid electrolyte, and the problems that the halide solid electrolyte is easy to absorb water, deliquesce and difficult to store are solved through polymer coating, so that the finally obtained composite electrode material has the characteristics of deliquescence and easy storage, and the lithium battery pole piece prepared by adopting the composite electrode material has excellent ionic conductivity because of containing the halide solid electrolyte coating.
In order to achieve the purpose, the invention adopts the following technical scheme:
a first aspect of the present invention provides a method of preparing a composite electrode material by coating an electrode material with a halide solid electrolyte and a polymer.
Preferably, the preparation method of the composite electrode material comprises the following steps:
(a) Adding an electrode material and a conductive agent into a halide solid electrolyte solution to obtain mixed slurry;
(b) Drying the mixed slurry to obtain an electrode material coated by halide salt;
(c) Roasting the electrode material coated with the halide salt under a vacuum condition to obtain an electrode material coated with a halide solid electrolyte;
(d) And adding the electrode material coated with the halide solid electrolyte into an oily solvent in which a polymer is dissolved, and drying to form the composite electrode material.
Preferably, in step (a):
the electrode material is a positive electrode material or a negative electrode material; and/or
The conductive agent is selected from one or more of carbon black, carbon nano tubes and graphene; and/or
The halide solid electrolyte is Li a MX b Or Li 3 Y 1-c In c X 6 Wherein M is a metal element selected from one of In, sc, Y and La, X is a halogen element, a is more than or equal to 0 and less than or equal to 10, b is more than or equal to 1 and less than or equal to 13, c is more than or equal to 0 and less than or equal to 13<1; and/or
The polymer is selected from one of PVDF, PVDF-HFP, PEO and PMMA; and/or
The concentration of the halide solid electrolyte solution is 0.1-20 wt%; and/or
The solvent of the halide solid electrolyte solution is a water-soluble solvent; and/or
The solid content of the mixed slurry is 25-50 wt%.
Preferably, in step (a):
the electrode material comprises one or more of LFP, LNMO, NCM, LTO, artificial graphite and silicon carbon material; and/or
Said has Li a MX b The halide solid electrolyte of (A) is selected from Li 3 InCl 6 、Li 3 YCl 6 、Li 3 ScCl 6 Or Li 3 InBr 6 One of (a) and (b); and/or
The water-soluble solvent is selected from water or alcohol.
Preferably, in the step (b):
the drying treatment method is spray drying, and the drying temperature is 90-140 ℃; or
The drying method comprises the steps of stirring, heating and drying, wherein the revolution speed is 2-40 m/min during stirring, and the drying temperature is 40-130 ℃; and/or
The halide salt contains crystal water, and the thickness of the coating layer of the electrode material coated by the halide salt is 1-200 nm.
Preferably, in the step (c), the roasting temperature is 200-350 ℃; and/or
In the step (d):
the polymer is selected from one or more of PVDF, PVDF-HFP, PEO and PMMA; and/or
The oily solvent is one selected from N-methyl pyrrolidone, tetrahydrofuran, ethylene carbonate and dimethyl carbonate; and/or
The drying method is spray drying, and the drying temperature is 90-140 ℃.
The invention provides a composite electrode material, which is prepared by the preparation method of the composite electrode material.
The third aspect of the invention provides a preparation method of a lithium battery pole piece, wherein the lithium battery pole piece is prepared from the composite electrode material prepared by the preparation method of the composite electrode material of the first aspect of the invention.
Preferably, the preparation method of the lithium battery pole piece comprises the following steps:
(1) Mixing a solid electrolyte, a conductive agent and the composite electrode material to obtain a dry mixed material;
(2) Adding an oily solvent or an oily solvent dissolved with a polymer into the dry-mixed material, mixing and stirring, and continuously adding the oily solvent for dilution to obtain electrode slurry;
(3) Stirring the electrode slurry, and simultaneously vacuumizing and defoaming to remove gas in the electrode slurry;
(4) And (4) coating and drying the electrode slurry treated in the step (3) on a base material to obtain the lithium battery pole piece.
Preferably, in the step (1):
the solid electrolyte is selected from one of polymer solid electrolyte, oxide solid electrolyte, sulfide solid electrolyte or halide solid electrolyte; and/or
The conductive agent is selected from one or more of carbon black, carbon nano tubes and graphene; and/or
In the mixing process, the revolution speed is 5-50 rpm during mixing.
Preferably, in the step (2):
the oily solvent is one selected from N-methyl pyrrolidone, tetrahydrofuran, ethylene carbonate and dimethyl carbonate; and/or
In the mixing process, the revolution speed is 20-60 rpm during mixing; and/or
In the dilution process, dispersing and stirring are adopted, and the dispersing speed is 1500-3000rpm during stirring; and/or
The viscosity of the electrode paste is 3000-20000 mPas.
Preferably, in the step (3), in the stirring treatment process, the revolution speed during stirring is 10-30 rpm; and/or
In the step (4), the base material is selected from one of an aluminum foil, a carbon-coated aluminum foil, a copper foil, a carbon-coated copper foil, a stainless steel foil or a halide solid electrolyte membrane.
The fourth aspect of the invention provides a lithium battery pole piece, which is prepared by the preparation method of the lithium battery pole piece.
The invention provides a preparation method of a composite electrode material and a preparation method of a lithium battery pole piece, which particularly have the following beneficial effects:
1. according to the invention, the halide solid electrolyte coated electrode material (anode/cathode material) can improve the ion conductivity of the anode/cathode material, and the problem that the halide solid electrolyte is easy to absorb water and deliquesce, easy to fall off after deliquescence, low in chemical stability and easy to react with a plurality of solvents and binders can be effectively solved after the halide solid electrolyte is coated by the polymer;
2. the composite electrode material adopts a composite structure design to effectively solve the problems that halide solid electrolyte is easy to deliquesce and difficult to store in the air;
3. the composite electrode material is prepared by sequentially using the halide solid electrolyte and the polymer-coated electrode material, and then the composite electrode material is slurried in an oily solvent and coated to form a lithium battery pole piece, so that the solid electrolyte in the lithium battery pole piece is more uniformly distributed.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:
FIG. 1 is a schematic structural diagram of a composite electrode material of the present invention;
fig. 2 is a schematic flow chart of a preparation method of the composite electrode material of the present invention.
Detailed Description
In order to better understand the technical scheme of the invention, the technical scheme of the invention is further explained by combining the embodiment.
Referring to fig. 1 and 2, the method for preparing a composite electrode material according to the present invention is prepared by coating a halide solid electrolyte and a polymer on an electrode material.
The preparation method of the composite electrode material comprises the following steps:
(a) Adding an electrode material and a conductive agent into a halide solid electrolyte solution to obtain mixed slurry;
the specific process is as follows: adding an electrode material (a positive electrode material or a negative electrode material) and a conductive agent into a halide solid electrolyte solution with a certain concentration to obtain mixed slurry, wherein the electrode material is the positive electrode material or the negative electrode material and is selected from one or more of LFP, LNMO, NCM, LTO, artificial graphite and silicon carbon material; the conductive agent is selected from one or more of carbon black, carbon nano tube and graphene; the halide solid electrolyte being Li a MX b Or Li 3 Y 1-c In c X 6 Wherein M is a metal element selected from one of In, sc, Y and La, X is a halogen element, a is more than or equal to 0 and less than or equal to 10, b is more than or equal to 1 and less than or equal to 13, c is more than or equal to 0 and less than or equal to 13<1, e.g. with Li a MX b The halide solid electrolyte of (A) is selected from Li 3 InCl 6 、Li 3 YCl 6 、Li 3 ScCl 6 Or Li 3 InBr 6 One of (1); the polymer is selected from one of PVDF, PVDF-HFP, PEO and PMMA; the concentration of the halide solid electrolyte solution is 0.1-20 wt%, wherein the solvent of the halide solid electrolyte solution adopts a water-soluble solvent, such as water or alcohol; the solid content of the mixed slurry is 25-50 wt%.
(b) Drying the mixed slurry to obtain an electrode material coated by halide salt;
the specific process is as follows: and drying the mixed slurry to form the electrode material coated with the halide salt, wherein the drying treatment method comprises the following steps: (1) spray drying, wherein the drying temperature is controlled to be 90-140 ℃; (2) Stirring, heating and drying, wherein the revolution speed during stirring is controlled to be 2-40 m/min, the drying temperature is controlled to be 40-130 ℃, and the drying treatment is finished when the liquid content in the material is lower than 10wt% during the drying process. In the electrode material coated by the halide salt formed in the process, the thickness of the coating layer is 1-200 nm, and the coating layer is the halide salt containing crystal water;
(c) Roasting the electrode material coated with the halide salt under a vacuum condition to obtain an electrode material coated with a halide solid electrolyte;
the specific process is as follows: and roasting the electrode material coated with the halide salt under a vacuum condition to remove crystal water in the halide salt to obtain the electrode material coated with the halide solid electrolyte, wherein the roasting temperature is 200-350 ℃.
(d) The electrode material coated with the halide solid electrolyte is added into an oily solvent in which a polymer is dissolved, and then dried to form a composite electrode material.
The specific process is as follows: the polymer is first dissolved in an oily solvent: adding a polymer, an active substance, a binder and a conductive agent into an oily solvent to obtain the oily solvent in which the polymer is dissolved, wherein the active substance, the binder and the conductive agent are used for dissolving the polymer into the oily solvent; selecting an active material according to the electrode material in the step (1), wherein if the electrode material is a positive electrode material, the active solvent is a positive electrode active material, and if the electrode material is a negative electrode material, the active solvent is a negative electrode active material; wherein the concentration of the polymer in the oily solvent is 1.5 to 3.0wt%. Adding the electrode material coated by the halide solid electrolyte into an oily solvent in which a polymer is dissolved, and drying to prepare a composite electrode; wherein the polymer is selected from one or more of PVDF, PVDF-HFP, PEO and PMMA; the oily solvent is one selected from N-methyl pyrrolidone, tetrahydrofuran, ethylene carbonate and dimethyl carbonate; the drying method in the step adopts spray drying, and the drying temperature is 90-140 ℃.
The structure of the prepared composite electrode material is shown in figure 1, and comprises an electrode material 1 of a core part, a halide solid electrolyte 2 coated on the surface of the electrode material 1 and a polymer 3 coated on the surface of the halide solid electrolyte 2, wherein the halide solid electrolyte 2 coats the electrode material 1 (positive/negative electrode material) to improve the ion conductivity of the positive/negative electrode material, and the problems that the halide solid electrolyte 2 is easy to absorb water, deliquesce and fall off after deliquescence, has low chemical stability and is easy to react with a plurality of solvents and binders can be effectively solved after being coated by the polymer 3.
The lithium battery pole piece can be prepared by adopting the prepared composite electrode material, wherein the preparation method of the lithium battery pole piece comprises the following steps:
(1) Mixing a solid electrolyte, a conductive agent and the composite electrode material prepared by the preparation method of the composite electrode material to obtain a dry mixed material;
the specific process is as follows: mixing the composite electrode material and the conductive agent to prepare a dry-mixed material, wherein the revolution speed is controlled to be 5-50 rpm during mixing; wherein the solid electrolyte is selected from one of polymer solid electrolyte, oxide solid electrolyte, sulfide solid electrolyte or halide solid electrolyte, the polymer solid electrolyte can be PEO, PAN, PVDF-HFP, etc., the oxide solid electrolyte can be LLZ, LLTO, LATP, LAGP, or their mixture, composite, etc., the sulfide solid electrolyte can be LPS, LGPS, LPSCl or LSPS, etc., and the halide solid electrolyte can be Li solid electrolyte a MX b Or Li 3 Y 1-c In c X 6 Wherein M is a metal element selected from In, sc, Y and La, X is a halogen element, a is more than or equal to 0 and less than or equal to 10, b is more than or equal to 1 and less than or equal to 13, c is more than or equal to 0 and less than or equal to 13<1, e.g. with Li a MX b The halide solid electrolyte of (A) is selected from Li 3 InCl 6 、Li 3 YCl 6 、Li 3 ScCl 6 Or Li 3 InBr 6 One of (1); the conductive agent is selected from carbon blackOne or more of carbon nano tube and graphene.
(2) Adding an oily solvent/an oily solvent containing a polymer into the dry-mixed material, uniformly mixing, and continuously adding the oily solvent for dilution to obtain electrode slurry;
the specific process is as follows: adding a proper amount of oily solvent into the dry-mixed materials, mixing and stirring, and controlling the revolution speed to be 20-60 rpm until the materials are in a moderate soft and hard state; continuously adding the oily solvent for dilution, adopting dispersion stirring in the dilution process, controlling the dispersion rotation speed to be 1500-3000rpm during stirring, and finally obtaining the electrode slurry with the viscosity of 3000-20000 mPas; wherein the oily solvent is one selected from N-methylpyrrolidone, tetrahydrofuran, ethylene carbonate and dimethyl carbonate.
(3) Stirring the electrode slurry, and simultaneously vacuumizing and defoaming to remove gas in the electrode slurry;
the specific process is as follows: and (3) stirring the electrode paste, controlling the revolution speed to be 10-30 rpm, and simultaneously performing vacuum-pumping defoaming treatment to remove gas in the electrode paste.
(4) And (4) coating and drying the electrode slurry treated in the step (3) on a base material to obtain the lithium battery pole piece.
The specific process is as follows: and (4) coating and drying the electrode slurry treated in the step (3) in a substrate to form the lithium battery pole piece, wherein the substrate is one selected from aluminum foil, carbon-coated aluminum foil, copper foil, carbon-coated copper foil, stainless steel foil or halide solid electrolyte membrane.
The preparation method of the composite electrode material and the preparation method of the lithium battery pole piece are further described by combining specific examples;
example 1
This example prepares PVDF-HFP/Li as follows 3 YCl 6 Coated lithium iron phosphate positive electrode material:
(a) Mixing Li 3 InCl 6 Adding into water to prepare halide solid electrolyte solution, li 3 InCl 6 Concentration of (3 wt%). Then adding CNT slurry (carbon nanotube slurry) and LFP (lithium iron phosphate) into the mixture containing halogen with certain concentrationForming mixed slurry by using the solid electrolyte solution, wherein the solid content of the mixed slurry is 27wt%;
(b) Carrying out spray drying on the mixed slurry to obtain an electrode material coated with halide salt, wherein the drying temperature is 120 ℃, and the spray pressure is 6MPa;
(c) Roasting the electrode material coated with the halide salt in vacuum to obtain an electrode material coated with a halide solid electrolyte, wherein the roasting temperature is 320 ℃;
(d) Adding an electrode material coated with a halide solid electrolyte into a pre-prepared PVDF-HFP/NMP solution, wherein the content of PVDF-HFP in the PVDF-HFP/NMP solution is 2.5wt%, and the solid content of the slurry is 50wt% after the electrode material coated with the halide solid electrolyte is added; spray drying to form PVDF-HFP/Li 3 YCl 6 The drying temperature of the coated lithium iron phosphate anode material (composite electrode material) is 110 ℃, and the spraying pressure is 12MPa.
PVDF-HFP/Li preparation in this example 3 YCl 6 Coated lithium iron phosphate positive electrode material and intermediate product Li 3 YCl 6 The coated lithium iron phosphate anode material and the uncoated lithium iron phosphate anode material are placed in the air together for 3 hours, and PVDF-HFP/Li 3 YCl 6 The water content of the coated lithium iron phosphate cathode material is 0.14 percent, and Li 3 YCl 6 The water content of the coated lithium iron phosphate anode material is 1.6%, and the water content of the uncoated lithium iron phosphate anode material is 0.42%.
Example 2
PVDF-HFP/Li prepared in example 1 3 YCl 6 The lithium battery pole piece is made of the coated lithium iron phosphate anode material and comprises the following steps:
(1) This example was used to prepare PVDF-HFP/Li 3 YCl 6 Adding the coated lithium iron phosphate anode material and SP material (carbon black) into a planetary pulping machine for dry mixing, wherein the revolution speed is 15rpm during stirring;
(2) Adding a proper amount of NMP solvent into the dry-mixed materials, and revolving at the revolution speed of 30rpm until the materials are in a state of moderate hardness; continuously adding NMP solvent for dilution, wherein the revolution speed is 50rpm, and the dispersion speed is 1500-3000rpm, until obtaining electrode slurry with the viscosity of 3000-20000 mPas;
(3) Carrying out vacuum defoaming on the electrode slurry at the revolution speed of 10 rpm;
(4) Coating the electrode slurry treated in the step (3) on an aluminum foil with the thickness of 9 mu m, wherein the surface density is 3mAh/cm 2 And drying by hot air at 110 ℃ to form the electrode plate.
The same preparation process is adopted to prepare the uncoated lithium iron phosphate into a lithium battery pole piece, the lithium battery pole piece and the lithium iron phosphate pole piece prepared in the embodiment are respectively assembled with artificial graphite in a matching way to form a lithium ion battery, 2C low-temperature discharge is carried out after the temperature is kept for 4h at-30 ℃ in a 100% SOC state, and the test result shows that the discharge capacity ratio of the battery assembled by the electrode pole piece in the embodiment is 79.66%, and the discharge capacity ratio of the battery assembled by the uncoated lithium iron phosphate pole piece is 70.14%.
Example 3
This example prepares PVDF-HFP/Li as follows 3 ScCl 6 Coated lithium iron phosphate positive electrode material:
(a) Mixing Li 3 ScCl 6 Adding into water to prepare a halide solid electrolyte solution, li 3 ScCl 6 Concentration of (2) 8wt%. Then adding SP (carbon black) and LFP (lithium iron phosphate) into a halide solid electrolyte solution with a certain concentration to form mixed slurry, wherein the solid content of the mixed slurry is 50wt%;
(b) Adopting a stirring, heating and drying mode: stirring the mixed slurry, gradually heating and evaporating the solvent to obtain an electrode material coated by halide salt, wherein the drying temperature is 80 ℃;
(c) Filtering out solid when the liquid content in the material is lower than 10wt%, paving the electrode material coated with the halide salt in vacuum, and roasting to obtain the electrode material coated with the halide solid electrolyte, wherein the roasting temperature is 320 ℃;
(d) Adding an electrode material coated by a halide solid electrolyte into a pre-prepared PVDF/NMP solution, wherein the content of PVDF in the PVDF/NMP solution is 2wt%, and the solid content of the slurry is 50wt% after the electrode material coated by the halide solid electrolyte is added; spray drying to form PVDF/Li 3 ScCl 6 Coated lithium iron phosphate anode material (composite electrode material), drying temperature 110 ℃, and spray pressureThe force is 12MPa.
PVDF/Li preparation in this example 3 ScCl 6 The lithium battery pole piece is made of the coated lithium iron phosphate anode material and comprises the following steps:
(1) Preparation of PVDF/Li from this example 3 ScCl 6 Coated lithium iron phosphate cathode material and LLZTO (oxide solid electrolyte Li) 6.4 La 3 Zr 1.4 Ta 0.6 O 12 ) Adding the SP material (carbon black) into a planetary pulping machine for dry mixing to obtain dry mixed material, wherein the revolution mixing rotating speed is 50rpm;
(2) Adding a proper amount of NMP solvent into the dry-mixed materials, and revolving at the revolution speed of 60rpm until the materials are in a state of moderate hardness; continuously adding NMP solvent for dilution, wherein the revolution speed is 50rpm, and the dispersion speed is 1500-3000rpm, until obtaining electrode slurry with the viscosity of 3000-20000 mPas;
(3) Carrying out vacuum defoaming on the electrode slurry at revolution speed of 14 rpm;
(4) Coating the electrode slurry treated in the step (3) on a 9 mu m aluminum foil with the surface density of 3mAh/cm 2 And drying by hot air at 110 ℃ to form the electrode plate.
Li is prepared by the same preparation process 3 ScCl 6 The coated lithium iron phosphate is prepared into a lithium battery pole piece, then the lithium battery pole piece and the electrode pole piece prepared in the embodiment are respectively used as a positive electrode, lithium metal is used as a negative electrode, PEO/LLZTO electrolyte is used as an intermediate layer to assemble a solid battery, and a charge-discharge cycle test is carried out at 45 ℃ and 0.5 ℃, and a test result shows that the cycle performance of the solid battery assembled by the electrode pole piece prepared in the embodiment is superior to that of the Li solid battery assembled by the electrode pole piece prepared in the embodiment 3 ScCl 6 When the capacity retention rate is 80%, the number of cycles of the solid-state battery assembled by the electrode plate of the embodiment is 281, and the number of cycles of the solid-state battery is Li 3 ScCl 6 The number of cycles of the solid-state battery assembled by the lithium battery pole piece prepared by the coated lithium iron phosphate material is 221.
Example 4
This example prepares PVDF/Li as follows 3 InCl 6 Coated silicon carbon electrode material:
(a) Mixing Li 3 InCl 6 Adding into water to prepare halide solid electrolyte solution, li 3 InCl 6 In a concentration of 10wt%. Then adding SP (carbon black) and silicon carbon into a halide solid electrolyte solution with a certain concentration to form mixed slurry, wherein the solid content of the mixed slurry is 40wt%;
(b) Adopting a stirring, heating and drying mode: stirring the mixed slurry, gradually heating and evaporating the solvent to obtain an electrode material coated by halide salt, wherein the drying temperature is 80 ℃;
(c) Filtering out solid when the liquid content in the material is lower than 10wt%, paving the electrode material coated with the halide salt in vacuum, and roasting to obtain the electrode material coated with the halide solid electrolyte, wherein the roasting temperature is 320 ℃;
(d) Adding an electrode material coated with a halide solid electrolyte into a pre-prepared PVDF/NMP solution, wherein the content of PVDF in the PVDF/NMP solution is 2.0wt%, and the solid content of slurry is 25wt% after the electrode material coated with the halide solid electrolyte is added; spray drying to form PVDF/Li 3 InCl 6 The drying temperature of the coated silicon-carbon electrode material (composite electrode material) is 110 ℃, and the spraying pressure is 12MPa.
PVDF/Li preparation in this example 3 InCl 6 The lithium battery pole piece is made of the coated silicon-carbon electrode material, and the steps are as follows:
(1) Preparation of PVDF/Li from this example 3 InCl 6 Coated silicon carbon electrode material and LLZTO (oxide solid electrolyte Li) 6.4 La 3 Zr 1.4 Ta 0.6 O 12 ) Adding the SP material (carbon black) into a planetary pulping machine for dry mixing to obtain dry mixed material, wherein the revolution mixing rotating speed is 15rpm;
(2) Adding a proper amount of PEO/NMP solvent into the dry-mixed material, wherein the concentration of PEO is 7%, and the revolution speed is 30rpm, until the material is in a state of moderate hardness; adding NMP solvent for dilution, wherein the revolution speed is 50rpm, and the dispersion speed is 1500-3000rpm until obtaining electrode slurry with the viscosity of 1500-12000 mPas;
(3) Carrying out vacuum defoaming on the electrode slurry at revolution speed of 10 rpm;
(4) Will be steps (3)The treated electrode slurry was coated on a 6 μm aluminum foil with an areal density of 3.4mAh/cm 2 And drying by hot air at 110 ℃ to form the electrode plate.
The same preparation process is adopted to prepare uncoated lithium iron phosphate into lithium battery pole pieces, then the lithium battery pole pieces and the electrode pole pieces prepared in the embodiment are respectively used as positive electrodes, lithium metal is used as a negative electrode, a PEO electrolyte membrane is used as an intermediate layer to assemble a solid-state battery, and a charge-discharge cycle test is carried out at 60 ℃ and 0.5 ℃, so that a test result shows that the cycle performance of the solid-state battery assembled by the electrode pole pieces prepared in the embodiment is superior to that of the lithium battery pole pieces prepared by the uncoated lithium iron phosphate material, wherein when the capacity retention rate is 80%, the cycle number of the solid-state battery assembled by the electrode pole pieces in the embodiment is 227 circles, and the Li is a lithium battery pole piece prepared by the electrode pole pieces prepared in the embodiment 3 ScCl 6 The number of circulating turns of the solid-state battery assembled by the lithium battery pole piece prepared by the coated lithium iron phosphate material is 196.
Example 5
This example prepares PVDF/Li as follows 3 InCl 6 Coated silicon carbon electrode material:
(a) Mixing Li 3 InCl 6 Adding into water to prepare a halide solid electrolyte solution, li 3 InCl 6 Concentration of (2) 20wt%. Then adding SP (carbon black) and silicon carbon into a halide solid electrolyte solution with a certain concentration to form mixed slurry, wherein the solid content of the mixed slurry is 50wt%;
(b) Adopting a stirring, heating and drying mode: stirring the mixed slurry, gradually heating and evaporating the solvent to obtain an electrode material coated by halide salt, wherein the drying temperature is 130 ℃;
(c) Filtering out the solid when the liquid content in the material is lower than 10wt%, paving the electrode material coated with the halide salt in vacuum, and roasting to obtain the electrode material coated with the halide solid electrolyte, wherein the roasting temperature is 350 ℃;
(d) Adding an electrode material coated with a halide solid electrolyte into a pre-prepared PVDF/NMP solution, wherein the content of PVDF in the PVDF/NMP solution is 2wt%, and the solid content of the slurry is 25wt% after the electrode material coated with the halide solid electrolyte is added; spray drying to form PVDF/Li 3 InCl 6 The drying temperature of the coated silicon-carbon electrode material (composite electrode material) is 110 ℃, and the spraying pressure is 12MPa.
PVDF/Li preparation in this example 3 InCl 6 The lithium battery pole piece is made of the coated silicon-carbon electrode material, and the steps are as follows:
(1) PVDF/Li preparation from this example 3 InCl 6 Coated silicon-carbon electrode material and LLZTO (oxide solid electrolyte Li) 6.4 La 3 Zr 1.4 Ta 0.6 O 12 ) Adding the SP material (carbon black) into a planetary pulping machine for dry mixing to obtain a dry mixed material, wherein the revolution mixing rotating speed is 5rpm;
(2) Adding a proper amount of NMP solvent into the dry-mixed materials, and revolving at the revolution speed of 60rpm until the materials are in a state of moderate hardness; continuously adding NMP solvent for dilution, wherein the revolution speed is 50rpm, and the dispersion speed is 1500-3000rpm, until obtaining electrode slurry with the viscosity of 1500-12000 mPas;
(3) The electrode slurry is subjected to vacuum defoaming at the revolution speed of 30rpm;
(4) Coating the electrode slurry treated in the step (3) on an aluminum foil with the thickness of 6 mu m, wherein the surface density is 3.4mAh/cm 2 And drying by hot air at 110 ℃ to form the electrode plate.
The same preparation process is adopted to prepare the uncoated silicon-carbon negative electrode material into a lithium ion battery pole piece, the lithium ion battery is assembled by matching the uncoated silicon-carbon negative electrode material and the silicon-carbon negative electrode pole piece prepared in the embodiment with the lithium iron phosphate in the embodiment 1 respectively, 2C low-temperature discharge is carried out after the temperature is maintained for 4h at the SOC state of 100 percent, -30 ℃, and the test result shows that the discharge capacity ratio of the battery assembled by the electrode pole piece in the embodiment is 82.41 percent, and the discharge capacity ratio of the battery assembled by the uncoated silicon-carbon negative electrode pole piece is 71.53 percent.
With reference to examples 1 to 5, the electrode sheet prepared from the polymer/halide-coated positive and negative electrode materials (composite electrode materials) as the electrode of the lithium ion battery has stability and electrochemical performance in air significantly better than those of the positive and negative electrode materials coated with only halides or the positive and negative electrode materials not coated with halides. Therefore, in the invention, the halide solid electrolyte coated electrode material (anode/cathode material) can improve the ion conductivity of the anode/cathode material, and the problem that the halide solid electrolyte is easy to absorb water, deliquesce, fall off after deliquescence, low in chemical stability and easy to react with a plurality of solvents and binders can be effectively solved after the halide solid electrolyte is coated by the polymer; the composite electrode material adopts a composite structure design to effectively solve the problems that halide solid electrolyte is easy to deliquesce and difficult to store in the air; the composite electrode material is prepared by sequentially using the halide solid electrolyte and the polymer-coated electrode material, and then the composite electrode material is slurried in an oily solvent and coated to form a lithium battery pole piece, so that the solid electrolyte in the lithium battery pole piece is more uniformly distributed; the lithium battery pole piece containing the halide solid electrolyte has the characteristic of low dispersion uniformity of the halide solid electrolyte.
It should be understood by those skilled in the art that the above embodiments are only for illustrating the present invention and are not to be used as a limitation of the present invention, and that changes and modifications to the above described embodiments are within the scope of the claims of the present invention as long as they are within the spirit and scope of the present invention.
Claims (13)
1. A preparation method of a composite electrode material is characterized in that the composite electrode material is prepared by coating a halide solid electrolyte and a polymer on the electrode material.
2. The method for preparing the composite electrode material according to claim 1, wherein the method for preparing the composite electrode material comprises the following steps:
(a) Adding an electrode material and a conductive agent into a halide solid electrolyte solution to obtain mixed slurry;
(b) Drying the mixed slurry to obtain a halide salt coated electrode material;
(c) Roasting the electrode material coated with the halide salt under a vacuum condition to obtain an electrode material coated with a halide solid electrolyte;
(d) And adding the electrode material coated with the halide solid electrolyte into an oily solvent in which a polymer is dissolved, and drying to form the composite electrode material.
3. The method for preparing a composite electrode material according to claim 2, wherein in the step (a):
the electrode material is a positive electrode material or a negative electrode material; and/or
The conductive agent is selected from one or more of carbon black, carbon nano tube and graphene; and/or
The halide solid electrolyte is Li a MX b Or Li 3 Y 1-c In c X 6 Wherein M is a metal element selected from one of In, sc, Y and La, X is a halogen element, a is more than or equal to 0 and less than or equal to 10, b is more than or equal to 1 and less than or equal to 13, c is more than or equal to 0 and less than or equal to 13<1; and/or
The polymer is selected from one of PVDF, PVDF-HFP, PEO and PMMA; and/or
The concentration of the halide solid electrolyte solution is 0.1-20 wt%; and/or
The solvent of the halide solid electrolyte solution is a water-soluble solvent; and/or
The solid content of the mixed slurry is 25-50 wt%.
4. The method for preparing a composite electrode material according to claim 3, wherein in the step (a):
the electrode material comprises one or more of LFP, LNMO, NCM, LTO, artificial graphite and silicon carbon material; and/or
Said has Li a MX b The halide solid electrolyte of (A) is selected from Li 3 InCl 6 、Li 3 YCl 6 、Li 3 ScCl 6 Or Li 3 InBr 6 One of (1); and/or
The water-soluble solvent is selected from water or alcohol.
5. The method for preparing a composite electrode material according to claim 2, wherein in the step (b):
the drying method is spray drying, and the drying temperature is 90-140 ℃; or
The drying method comprises the steps of stirring, heating and drying, wherein the revolution speed is 2-40 m/min during stirring, and the drying temperature is 40-130 ℃; and/or
The halide salt contains crystal water, and the thickness of the coating layer of the electrode material coated by the halide salt is 1-200 nm.
6. The method for producing a composite electrode material according to claim 2,
in the step (c), the roasting temperature is 200-350 ℃; and/or
In said step (d):
the polymer is selected from one or more of PVDF, PVDF-HFP, PEO and PMMA; and/or
The oily solvent is one selected from N-methyl pyrrolidone, tetrahydrofuran, ethylene carbonate and dimethyl carbonate; and/or
The drying method is spray drying, and the drying temperature is 90-140 ℃.
7. A composite electrode material, characterized in that it is produced by a method for producing a composite electrode material according to any one of claims 1 to 6.
8. A preparation method of a lithium battery pole piece is characterized in that the lithium battery pole piece is prepared by adopting the composite electrode material prepared by the preparation method of the composite electrode material according to any one of claims 1 to 6.
9. The method for preparing the lithium battery pole piece as claimed in claim 8, wherein the method for preparing the lithium battery pole piece comprises the following steps:
(1) Mixing a solid electrolyte, a conductive agent and the composite electrode material to obtain a dry mixed material;
(2) Adding an oily solvent or an oily solvent dissolved with a polymer into the dry-mixed material, mixing and stirring, and then continuously adding the oily solvent for dilution to obtain electrode slurry;
(3) Stirring the electrode slurry, and simultaneously vacuumizing and defoaming to remove gas in the electrode slurry;
(4) And (4) coating and drying the electrode slurry treated in the step (3) on a base material to obtain the lithium battery pole piece.
10. The method for preparing the lithium battery pole piece according to claim 9, wherein in the step (1):
the solid electrolyte is selected from one of polymer solid electrolyte, oxide solid electrolyte, sulfide solid electrolyte or halide solid electrolyte; and/or
The conductive agent is selected from one or more of carbon black, carbon nano tube and graphene; and/or
In the mixing process, the revolution speed is 5-50 rpm during mixing.
11. The method for manufacturing a lithium battery pole piece according to claim 9,
in the step (2):
the oily solvent is one selected from N-methyl pyrrolidone, tetrahydrofuran, ethylene carbonate and dimethyl carbonate; and/or
In the mixing process, the revolution speed is 20-60 rpm during mixing; and/or
In the dilution process, dispersing and stirring are adopted, and the dispersing speed is 1500-3000rpm during stirring; and/or
The viscosity of the electrode paste is 3000-20000 mPas.
12. The method for manufacturing a lithium battery pole piece according to claim 9,
in the step (3), in the stirring treatment process, the revolution speed is 10-30 rpm during stirring; and/or
In the step (4), the base material is selected from one of an aluminum foil, a carbon-coated aluminum foil, a copper foil, a carbon-coated copper foil, a stainless steel foil or a halide solid electrolyte membrane.
13. A lithium battery pole piece, characterized in that it is prepared by the method of any one of claims 8-12.
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| CN116705998B (en) * | 2023-07-18 | 2024-02-09 | 哈尔滨工业大学 | Preparation method of solid-state battery composite anode |
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