Layered composite solid electrolyte and preparation method thereof

Abstract

The invention belongs to the technical field of lithium ion battery materials, and discloses a layered composite lithium ion battery solid electrolyte and a preparation method thereof.The preparation method comprises the steps that firstly, modified electrolyte slurry on the two sides of a positive electrode and a negative electrode is prepared, and the positive electrode slurry and the negative electrode slurry are further coated on a positive plate; and then coating the negative electrode measurement slurry on the positive electrode measurement slurry to obtain a composite modified pole piece, and then carrying out medium-temperature reaction and high-temperature drying on the pole piece to form the layered composite lithium ion battery solid electrolyte. The preparation method is simple in process and high in adaptability, and the layered structure design can be adjusted according to the requirements of different types of lithium ion batteries. The prepared solid electrolyte has excellent conductivity, mechanical strength and interface stability, and the performance and safety of the battery in the high-voltage and long-term cycle process are remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of manufacturing solid electrolytes for lithium-ion batteries, and particularly relates to a laminated composite solid electrolyte for lithium-ion batteries and a preparation method thereof. Background Art

[0002] As a core material in lithium batteries, solid-state electrolytes (SSEs) have the potential to replace liquid electrolytes. Their main advantages include high safety, no leakage of toxic liquids, low flammability, good thermal stability, excellent mechanical properties, and low self-discharge rate. In addition, solid-state electrolytes can also achieve higher energy density and longer cycle life, providing important support for the next generation of high-performance batteries.

[0003] Among solid-state electrolytes, polymer solid electrolytes have attracted much attention due to their high flexibility, good interfacial contact, and ionic conductivity. Common polymer-based solid electrolyte materials include polyethylene oxide (PEO), polyacrylate (PAA), and polycarbonate (PC). These polymer materials can combine with lithium salts to form a conductive system, having a high ionic mobility and good processing properties. However, due to problems such as serious side reactions at the positive and negative electrode interfaces, poor mechanical strength, and low ionic conductivity in polymer solid electrolytes. Therefore, it is necessary to seek a method to optimize the structure of the positive and negative electrode interfaces, which has become an important topic at present.

[0004] We propose a method of constructing a laminated composite of solid electrolytes. By optimizing the design of the solid electrolyte materials in layers, materials with specific functions can be introduced into different layers. In view of the different functional requirements of the positive and negative electrodes in the present invention, oxide, fillers of oxide electrolytes, and PVDF polymer membranes are respectively coated in layers, simultaneously meeting the modification of both poles of the battery, not only greatly enhancing the mechanical strength of the electrolyte, but also improving the problem of the stability of the positive and negative electrode interfaces. Summary of the Invention

[0005] The present invention provides a laminated composite solid electrolyte for lithium-ion batteries and a preparation method thereof. First, based on a traditional eight-series positive electrode sheet, two layers of pre-prepared PVDF-HFP positive and negative electrode modification materials are in-situ coated thereon, and finally, a staged drying treatment is carried out to obtain a laminated composite solid electrolyte for lithium-ion batteries. The interfacial impedance of this electrolyte is improved, and the mechanical flexibility is also effectively enhanced.

[0006] The object of the present invention is specifically achieved through the following technical solutions:

[0007] A preparation method of a laminated composite solid electrolyte for lithium-ion batteries, comprising the following steps:

[0008] (1) Grind and mix a certain proportion of lithium salts, solvents, binders, polymer monomers, and oxide electrolytes uniformly to obtain a positive electrode side electrolyte slurry;

[0009] (2) Grind and mix a certain proportion of lithium salts, solvents, binders, initiators, and oxides uniformly to obtain a negative electrode side electrolyte slurry;

[0010] (3) First, spray the positive electrode side slurry described in step (1) onto the existing positive electrode paste with a certain surface density and thickness, and then apply the negative electrode side slurry described in (2) onto the positive electrode side slurry with a certain surface density and thickness to obtain a composite modified electrode sheet;

[0011] (4) Carry out medium-temperature reaction and high-temperature drying on the electrode sheet obtained in step (3) to obtain a layered composite lithium-ion battery solid electrolyte.

[0012] Preferably, the lithium salt described in step (1) is at least one of LiFSI, LiTFSI, LiBF 4 , LiPF 6 , LiNO 3 , LiClO 4 .

[0013] Preferably, the solvent described in step (1) is at least one of DME (ethylene glycol dimethyl ether), EGME (ethylene glycol methyl ether), and ethylene glycol diethyl ether.

[0014] Preferably, the binder described in step (1) is at least one of PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene), PVDF-TrFE (polyvinylidene fluoride-trifluoroethylene), PVDF-CTFE (polyvinylidene fluoride-chlorotrifluoroethylene), and PVDF-TFE (polyvinylidene fluoride-tetrafluoroethylene).

[0015] Preferably, the polymer monomer described in step (1) is at least one of PEGDA (polyethylene glycol diacrylate), PEGMA (polyethylene glycol methacrylate), PEGMEA (polyethylene glycol methyl ether acrylate), and PEGDMA (polyethylene glycol dimethacrylate).

[0016] Preferably, the oxide electrolyte described in step (1) is at least one of LLZTO (lithium lanthanum zirconium tantalum oxide), LLZO-Al (lithium lanthanum zirconium aluminum oxide), LLZO-Y (lithium lanthanum zirconium yttrium oxide), LLFTO (lithium lanthanum titanium iron oxide), and LLTO (lithium lanthanum titanium oxide).

[0017] Preferably, the mass ratio range of the binder, polymer monomer, oxide electrolyte, lithium salt, and solvent described in step (1) is 1:(0.4 - 0.6):(0.15 - 0.25):(1.1 - 1.4):(9 - 13).

[0018] Preferably, the lithium salt in step (2) is at least one of LiFSI, LiTFSI, LiBF 4 , LiPF 6 , LiNO 3 , LiClO 4 .

[0019] Preferably, the solvent in step (2) is at least one of DME (ethylene glycol dimethyl ether), EGME (ethylene glycol methyl ether), and ethylene glycol diethyl ether.

[0020] Preferably, the binder in step (2) is at least one of PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene), PVDF-TrFE (polyvinylidene fluoride-trifluoroethylene), PVDF-CTFE (polyvinylidene fluoride-chlorotrifluoroethylene), and PVDF-TFE (polyvinylidene fluoride-tetrafluoroethylene).

[0021] Preferably, the initiator in step (2) is at least one of AIBN (azobisisobutyronitrile), BPO (benzoyl peroxide), DMP-30 (2,4,6-tris(dimethylaminomethyl)phenol), and DMAP (4-dimethylaminopyridine).

[0022] Preferably, the oxide in step (2) is at least one of Al 2 O 3 (aluminum oxide), ZrO 2 (zirconium oxide), MgO (magnesium oxide), TiO 2 (titanium oxide), SnO 2 (tin oxide), SiO 2 (silicon oxide).

[0023] Preferably, the mass ratio range of the binder, initiator, oxide, lithium salt, and solvent in step (2) is 1:(0.004 - 0.006):(0.15 - 0.25):(1.1 - 1.4):(9 - 13).

[0024] Preferably, the active material in the existing positive electrode slurry in step (3) is Ni x Co y Mn 1-x-y , (where x, y, and 1 - x - y are all between 0 and 1), and the mass content of the positive electrode active material is 75% - 95%, the coating surface density is 1 - 10 mg / cm 2 , and the thickness is 180 - 200 μm.

[0025] Preferably, the surface density of the sprayed slurry in step (3) is 12 - 18 mg / cm 2, the slurry thickness is 80 - 120 μm.

[0026] Preferably, in step (4), the temperature of the medium-temperature reaction is 40 - 60 °C, and the time of the medium-temperature reaction is 2 - 5 hours.

[0027] Preferably, in step (4), the temperature of the high-temperature drying is 90 - 120 °C, and the time of the high-temperature drying is 3 - 6 hours.

[0028] Through the method of layered coating and constructing a gradient or functional electrolyte layer on both sides of the positive and negative electrodes, the present invention realizes an optimized balance of ionic conductivity among regions, improves the chemical stability in the electrolyte while enhancing the mechanical strength, strengthens the bonding force with the electrode, and ultimately improves the overall performance of the battery. The present invention designs a preparation method with simple operation and capable of realizing large-scale synthesis, providing certain reference and basis for the preparation research of layered composite solid electrolytes for lithium-ion batteries in the future. Description of the Drawings

[0029] Figure 1 It is the cycle performance diagram of the batteries assembled with the solid electrolytes obtained in Example 1, Example 2, Comparative Example 1, Example 3, Example 4, Example 5, Example 6, Comparative Example 2, Comparative Example 3, and Comparative Example 4. Detailed Embodiments

[0030] Example 1

[0031] (1) Take 1 g of PVDF-HFP, 0.5 g of PEGDA, 0.2 g of LLZTO, 1.2 g of LiFSI, and 10 g of DME, and grind and mix them evenly to obtain the electrolyte slurry for the positive electrode side.

[0032] (2) Take 1 g of PVDF-HFP, 0.005 g of AIBN, 0.2 g of Al 2 O 3 , 1.2 g of LiFSI, and 10 g of DME, and grind and mix them evenly to obtain the electrolyte slurry for the negative electrode side.

[0033] (3) Mix the commercial eight-series (LiNi 0.8 Co 0.1 Mn 0.1 O 2 ) ternary cathode material with the conductive agent acetylene black (AB) and the binder polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1, use N-methylpyrrolidone (NMP) as the solvent, place it in a small beaker and stir and mix the materials at a speed of 800 r / min for 2 h to obtain the cathode slurry. Then, the cathode slurry is applied with a surface density of 5 mg / cm 2, is evenly coated on the aluminum foil with a value of 200 μm in thickness. The positive electrode side slurry described in step (1) is evenly sprayed on the positive electrode slurry with a surface density of 18 mg / cm 2 and a thickness of 100 μm. Then, the negative electrode side slurry described in step (2) is evenly sprayed on the positive electrode side slurry with a surface density of 18 mg / cm 2 and a thickness of 100 μm, thus obtaining the composite modified electrolyte.

[0034] (4) The composite modified electrolyte obtained in step (3) is first subjected to a medium-temperature reaction, reacted at 50 °C for 3 hours, and then taken out for high-temperature drying, dried at 100 °C for 4 hours, thus obtaining the layered composite lithium-ion battery solid electrolyte.

[0035] The obtained layered composite lithium-ion battery solid electrolyte is cut into circular electrodes with a diameter of 16 mm as the positive electrode and solid electrolyte of the lithium-ion battery, and placed in a glove box with a water content and oxygen content both lower than 0.1 ppm and filled with an argon atmosphere for 4 h to reduce the moisture adsorbed by the electrodes during the transfer process. A circular lithium sheet cut into a diameter of 16 mm is used as the negative electrode. Then, it is assembled into a CR2032 coin-type battery in the glove box.

[0036] After the battery assembly is completed and aged for 12 h, charge and discharge tests at different potentials are carried out. The discharge specific capacity of the calcined sample after 100 cycles at a current density of 1.0 C under a voltage of 2.8 - 4.3 V is 172.54 mAhg -1 . And the ionic conductivity of this sample is measured to be 2.58×10 -4 S / cm.

[0037] Comparative Example 1

[0038] (1) Take 1 g of PVDF-HFP, 0.5 g of PEGDA, 0.2 g of LLZTO, 1.2 g of LiFSI, and 10 g of DME, and grind and mix them evenly to obtain the positive electrode side electrolyte slurry.

[0039] (2) Mix the commercial eight-series (LiNi 0.8 Co 0.1 Mn 0.1 O 2 ) ternary cathode material with the conductive agent acetylene black (AB) and the binder polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1, use N-methylpyrrolidone (NMP) as the solvent, place it in a small beaker, and stir and mix the materials at a speed of 800 r / min for 2 h to obtain the positive electrode slurry. Then, the positive electrode slurry is evenly coated on the aluminum foil with a surface density of 5 mg / cm 2 and a thickness of 200 μm. The positive electrode side slurry described in step 1) is applied at 18 mg / cm 2The areal density is evenly sprayed on the positive electrode slurry with a thickness of 200 μm to obtain the composite modified electrolyte.

[0040] (3) The composite modified electrolyte obtained in step (2) is first subjected to a medium-temperature reaction, reacted at 50 °C for 3 hours, and then the electrolyte is taken out and dried at high temperature, dried at 100 °C for 4 hours to obtain a layered composite lithium-ion battery solid electrolyte.

[0041] The obtained layered composite lithium-ion battery solid electrolyte is cut into circular electrodes with a diameter of 16 mm as the positive electrode and solid electrolyte of the lithium-ion battery, and placed in a glove box with a water content and oxygen content both lower than 0.1 ppm and filled with an argon atmosphere for 4 h to reduce the moisture adsorbed by the electrode during transfer. A circular lithium sheet cut into a diameter of 16 mm is used as the negative electrode. Then it is assembled into a CR2032 coin-type battery in the glove box.

[0042] After the battery assembly is completed and aged for 12 h, charge and discharge tests at different potentials are carried out. The discharge specific capacity of the calcined sample after 100 cycles at a current density of 1.0C under a voltage of 2.8 - 4.3V is 133 mAh g -1 . And the ionic conductivity of this sample is measured to be 0.85×10 -4 S / cm.

[0043] Comparative Example 2

[0044] (1) Take 1 g of PVDF-HFP, 0.005 g of AIBN, 0.2 g of Al 2 O 3 , 1.2 g of LiFSI, 10 g of DME and grind them evenly to obtain the negative electrode side electrolyte slurry.

[0045] (2) The commercial eight-series (LiNi 0.8 Co 0.1 Mn 0.1 O 2 ) ternary cathode material, conductive agent acetylene black (AB), and binder polyvinylidene fluoride (PVDF) are mixed in a mass ratio of 8:1:1, using N-methylpyrrolidone (NMP) as a solvent, placed in a small beaker and stirred and mixed at a speed of 800 r / min for 2 h to obtain the positive electrode slurry. Then the positive electrode slurry is evenly coated on the aluminum foil with an areal density of 5 mg / cm 2 , and a thickness of 200 μm. The negative electrode side slurry described in step (1) is evenly sprayed on the positive electrode slurry with an areal density of 18 mg / cm 2 , and a thickness of 200 μm to obtain the composite modified electrolyte.

[0046] (3) The composite modified electrolyte obtained in step (2) is first subjected to a medium-temperature reaction, reacted at 50 °C for 3 hours, and then the electrolyte is taken out and dried at a high temperature, dried at 100 °C for 4 hours, and a layered composite lithium-ion battery solid electrolyte is obtained.

[0047] The obtained layered composite lithium-ion battery solid electrolyte is cut into a circular electrode sheet with a diameter of 16 mm as the positive electrode and solid electrolyte of the lithium-ion battery, and placed in a glove box with a water content and oxygen content both lower than 0.1 ppm and filled with an argon atmosphere for 4 h to reduce the moisture adsorbed by the electrode sheet during the transfer process. A circular lithium sheet cut into a diameter of 16 mm is used as the negative electrode. Then, it is assembled into a CR2032 coin-type battery in the glove box.

[0048] After the battery assembly is completed and aged for 12 h, charge-discharge tests at different potentials are carried out. The discharge specific capacity of the calcined sample after 100 cycles at a current density of 1.0C under a voltage of 2.8 - 4.3V is 120.28 mAhg -1 And the ionic conductivity of this sample is measured to be 0.73×10 -4 S / cm.

[0049] Comparative Example 3

[0050] (1) Take 1 g of PVDF-HFP, 0.5 g of PEGDA, 1.2 g of LiFSI, and 10 g of DME, and grind and mix them evenly to obtain the positive electrode side electrolyte slurry.

[0051] (2) Take 1 g of PVDF-HFP, 0.005 g of AIBN, 0.2 g of Al 2 O 3 、1.2 g of LiFSI, and 10 g of DME, and grind and mix them evenly to obtain the negative electrode side electrolyte slurry.

[0052] (3) Mix the commercial octa-system (LiNi 0.8 Co 0.1 Mn 0.1 O 2 ) ternary cathode material with the conductive agent acetylene black (AB) and the binder polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1, use N-methylpyrrolidone (NMP) as the solvent, place it in a small beaker and stir and mix the materials at a speed of 800 r / min for 2 h to obtain the positive electrode slurry. Then, the positive electrode slurry is uniformly coated on the aluminum foil with a surface density of 5 mg / cm 2 , and a thickness of 200 μm. The positive electrode side slurry described in step (1) is uniformly sprayed on the positive electrode slurry with a surface density of 18 mg / cm 2 , and a thickness of 100 μm. Then, the negative electrode side slurry described in step (2) is uniformly sprayed on it with a surface density of 18 mg / cm 2The areal density is evenly sprayed on the positive electrode slurry with a thickness of 100 μm, and the composite modified electrolyte is obtained.

[0053] (4) The composite modified electrolyte obtained in step (3) is first subjected to a medium-temperature reaction, reacted at 50 °C for 3 hours, and then the electrolyte is taken out and dried at a high temperature, dried at 100 °C for 4 hours, and the layered composite lithium-ion battery solid electrolyte is obtained.

[0054] The above-obtained layered composite lithium-ion battery solid electrolyte is cut into a circular pole piece with a diameter of 16 mm as the positive electrode and solid electrolyte of the lithium-ion battery, and placed in a glove box with a water content and oxygen content both lower than 0.1 ppm and filled with an argon atmosphere for 4 h to reduce the moisture adsorbed by the pole piece during the transfer process. A circular lithium piece cut into a diameter of 16 mm is used as the negative electrode. Then it is assembled into a CR2032 type button battery in the glove box.

[0055] After the battery assembly is completed and aged for 12 h, charge and discharge tests at different potentials are carried out. The discharge specific capacity of the sample after calcination at a voltage of 2.8 - 4.3 V and a current density of 1.0 C after 100 cycles is 87.1 mAh g -1 . And the ionic conductivity of this sample is measured to be 0.54×10 -4 S / cm.

[0056] Comparative Example 4

[0057] (1) Take 1 g of PVDF-HFP, 0.5 g of PEGDA, 0.2 g of LLZTO, 1.2 g of LiFSI, and 10 g of DME, and grind and mix them evenly to obtain the positive electrode electrolyte slurry.

[0058] (2) Take 1 g of PVDF-HFP, 0.005 g of AIBN, 1.2 g of LiFSI, and 10 g of DME, and grind and mix them evenly to obtain the negative electrode electrolyte slurry.

[0059] (3) Mix the commercial octa-system (LiNi 0.8 Co 0.1 Mn 0.1 O 2 ) ternary cathode material with the conductive agent acetylene black (AB) and the binder polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1, use N-methylpyrrolidone (NMP) as the solvent, place it in a small beaker and stir and mix the materials at a speed of 800 r / min for 2 h to obtain the positive electrode slurry. Then the positive electrode slurry is evenly coated on the aluminum foil with an areal density of 5 mg / cm 2 , and a thickness of 200 μm. The positive electrode electrolyte slurry described in step (1) is applied at 18 mg / cm 2The areal density is evenly sprayed on the positive electrode slurry with a thickness of 100 μm. Then, the negative electrode side slurry described in step (2) is applied at 18 mg / cm 2 The areal density is evenly sprayed on the positive electrode side slurry with a thickness of 100 μm, and the composite modified electrolyte is obtained.

[0060] (4) The composite modified electrolyte obtained in step (3) is first subjected to a medium-temperature reaction and reacted at 50 °C for 3 hours. Then, the electrolyte is taken out and dried at a high temperature, dried at 100 °C for 4 hours, and the layered composite lithium-ion battery solid electrolyte is obtained.

[0061] The obtained layered composite lithium-ion battery solid electrolyte is cut into circular electrodes with a diameter of 16 mm as the positive electrode and solid electrolyte of the lithium-ion battery. It is placed in a glove box with a water content and oxygen content both lower than 0.1 ppm and filled with an argon atmosphere for 4 h to reduce the moisture adsorbed by the electrode during transfer. A circular lithium sheet cut into a diameter of 16 mm is used as the negative electrode. Then, it is assembled into a CR2032 coin-type battery in the glove box.

[0062] After the battery assembly is completed and aged for 12 h, charge and discharge tests are carried out at different potentials. The discharge specific capacity of the calcined sample after 100 cycles at a current density of 1.0C under a voltage of 2.8 - 4.3V is 60.09 mA h g -1 . And the ionic conductivity of this sample is measured to be 0.61×10 -4 S / cm.

[0063] Example 2

[0064] (1) Take 1 g of PVDF-HFP, 0.5 g of PEGDA, 0.2 g of LLZTO, 1.2 g of LiFSI, and 10 g of EGME, and grind and mix them evenly to obtain the positive electrode side electrolyte slurry.

[0065] (2) Take 1 g of PVDF-HFP, 0.005 g of AIBN, 0.2 g of Al 2 O 3 , 1.2 g of LiFSI, and 10 g of EGME, and grind and mix them evenly to obtain the negative electrode side electrolyte slurry.

[0066] (3) The commercial eight-series (LiNi 0.8 Co 0.1 Mn 0.1 O 2)The ternary cathode material is mixed with acetylene black (AB) as the conductive agent and polyvinylidene fluoride (PVDF) as the binder in a mass ratio of 8:1:1. Using N-methylpyrrolidone (NMP) as the solvent, it is placed in a small beaker and stirred at a speed of 800 r / min for 2 h to obtain the cathode slurry. Then, the cathode slurry is uniformly coated on the aluminum foil at a surface density of 5 mg / cm 2 and a thickness of 200 μm. The cathode-side slurry described in step (1) is uniformly sprayed on the cathode slurry at a surface density of 18 mg / cm 2 and a thickness of 100 μm. Then, the negative electrode-side slurry described in step (2) is uniformly sprayed on the cathode-side slurry at a surface density of 18 mg / cm 2 and a thickness of 100 μm to obtain the composite modified electrolyte.

[0067] (4) The composite modified electrolyte obtained in step (3) is first subjected to a medium-temperature reaction and reacted at 50 °C for 3 hours, and then the electrolyte is taken out and dried at a high temperature and dried at 100 °C for 4 hours to obtain a layered composite lithium-ion battery solid electrolyte.

[0068] The obtained layered composite lithium-ion battery solid electrolyte is cut into circular electrodes with a diameter of 16 mm as the positive electrode and solid electrolyte of the lithium-ion battery, and placed in a glove box with a water content and oxygen content both lower than 0.1 ppm and filled with an argon atmosphere for 4 h to reduce the moisture adsorbed by the electrode during the transfer process. A circular lithium sheet cut into a diameter of 16 mm is used as the negative electrode. Then, it is assembled into a CR2032 type button battery in the glove box.

[0069] After the battery assembly is completed and aged for 12 h, charge and discharge tests at different potentials are carried out. The discharge specific capacity of the sample after calcination at a voltage of 2.8 - 4.3 V and a current density of 1.0 C after 100 cycles is 170.65 mA hg -1 . And the ionic conductivity of this sample is measured to be 2.64×10 -4 S / cm.

[0070] Example 3

[0071] (1) Take 1 g of PVDF-HFP, 0.5 g of PEGDA, 0.2 g of LLZO-Al, 1.2 g of LiFSI, and 10 g of DME and grind them evenly to mix, and obtain the cathode-side electrolyte slurry.

[0072] (2) Take 1 g of PVDF-HFP, 0.005 g of AIBN, 0.2 g of Al 2 O 3 , 1.2 g of LiFSI, and 10 g of DME and grind them evenly to mix, and obtain the negative electrode-side electrolyte slurry.

[0073] (3) Mix the commercial octa-system (LiNi 0.8 Co 0.1 Mn 0.1 O 2 ) ternary cathode material with conductive agent acetylene black (AB) and binder polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1. Using N-methylpyrrolidone (NMP) as the solvent, place it in a small beaker and stir the mixture at a speed of 800 r / min for 2 h to obtain the positive electrode slurry. Then, apply the positive electrode slurry evenly on the aluminum foil with a surface density of 5 mg / cm 2 and a thickness of 200 μm. Apply the positive electrode side slurry described in step (1) on the positive electrode slurry with a surface density of 18 mg / cm 2 and a thickness of 100 μm. Then, apply the negative electrode side slurry described in step (2) on the positive electrode side slurry with a surface density of 18 mg / cm 2 and a thickness of 100 μm to obtain the composite modified electrolyte.

[0074] (4) First, conduct a medium-temperature reaction on the composite modified electrolyte obtained in step (3). React at 50 °C for 3 hours, and then take out the electrolyte for high-temperature drying. Dry it at 100 °C for 4 hours to obtain the layered composite lithium-ion battery solid electrolyte.

[0075] Cut the obtained layered composite lithium-ion battery solid electrolyte into circular electrodes with a diameter of 16 mm as the positive electrode and solid electrolyte of the lithium-ion battery. Place it in a glove box with a water content and oxygen content both lower than 0.1 ppm and filled with an argon atmosphere for 4 h to reduce the moisture adsorbed by the electrode during transfer. Use a circular lithium sheet with a diameter of 16 mm as the negative electrode. Then, assemble it into a CR2032 type button battery in the glove box.

[0076] After the battery assembly is completed and aged for 12 h, perform charge and discharge tests at different potentials. The discharge specific capacity of the calcined sample after 100 cycles at a current density of 1.0 C under a voltage of 2.8 - 4.3 V is 169.82 mA hg -1 . And the ionic conductivity of this sample is measured to be 2.75×10 -4 S / cm.

[0077] Example 4

[0078] (1) Take 1 g of PVDF-HFP, 0.5 g of PEGMEA, 0.2 g of LLZTO, 1.2 g of LiFSI, and 10 g of DME and grind and mix them evenly to obtain the positive electrode side electrolyte slurry.

[0079] (2) Take 1 g of PVDF-HFP, 0.005 g of AIBN, 0.2 g of Al2 O 3 、 1.2 g of LiFSI and 10 g of DME are evenly ground and mixed to obtain the electrolyte slurry for the negative electrode side.

[0080] (3) Mix the commercial octa-system (LiNi 0.8 Co 0.1 Mn 0.1 O 2 ) ternary cathode material with the conductive agent acetylene black (AB) and the binder polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1. Using N-methylpyrrolidone (NMP) as the solvent, place it in a small beaker and stir the mixture at a speed of 800 r / min for 2 h to obtain the cathode slurry. Then, coat the cathode slurry evenly on the aluminum foil with a surface density of 5 mg / cm 2 and a thickness of 200 μm. Spray the cathode-side slurry described in step (1) evenly on the cathode slurry with a surface density of 18 mg / cm 2 and a thickness of 100 μm. Then, spray the negative electrode side slurry described in step (2) evenly on the cathode-side slurry with a surface density of 18 mg / cm 2 and a thickness of 100 μm to obtain the composite modified electrolyte.

[0081] (4) First, perform a medium-temperature reaction on the composite modified electrolyte obtained in step (3), react at 50 °C for 3 hours, and then take out the electrolyte for high-temperature drying, drying at 100 °C for 4 hours to obtain the layered composite lithium-ion battery solid electrolyte.

[0082] Cut the obtained layered composite lithium-ion battery solid electrolyte into circular electrodes with a diameter of 16 mm as the positive electrode and solid electrolyte of the lithium-ion battery. Place it in a glove box with a water content and oxygen content both lower than 0.1 ppm and filled with an argon atmosphere for 4 h to reduce the moisture adsorbed by the electrode during the transfer process. Use a circular lithium sheet cut into a diameter of 16 mm as the negative electrode. Then assemble it into a CR2032 type button battery in the glove box.

[0083] After the battery assembly is completed and aged for 12 h, perform charge and discharge tests at different potentials. The discharge specific capacity of the sample after calcination at a voltage of 2.8 - 4.3 V and a current density of 1.0 C after 100 cycles is 168.31 mA hg -1 . And the ionic conductivity of this sample is measured to be 2.86×10 -4 S / cm.

[0084] Example 5

[0085] (1) Take 1 g of PVDF-HFP, 0.5 g of PEGDA, 0.2 g of LLZTO, 1.2 g of LiFSI, and 10 g of DME, and grind and mix them evenly to obtain the positive electrode side electrolyte slurry.

[0086] (2) Take 1 g of PVDF-HFP, 0.005 g of BPO, 0.2 g of Al 2 O 3 , 1.2 g of LiFSI, and 10 g of DME, and grind and mix them evenly to obtain the negative electrode side electrolyte slurry.

[0087] (3) Mix the commercial eight-series (LiNi 0.8 Co 0.1 Mn 0.1 O 2 ) ternary cathode material with the conductive agent acetylene black (AB) and the binder polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1. Using N-methylpyrrolidone (NMP) as the solvent, place it in a small beaker and stir the mixture at a speed of 800 r / min for 2 h to obtain the positive electrode slurry. Then, coat the positive electrode slurry evenly on the aluminum foil at a surface density of 5 mg / cm 2 and a thickness of 200 μm. Spray the positive electrode side slurry described in step (1) evenly on the positive electrode slurry at a surface density of 18 mg / cm 2 and a thickness of 100 μm. Then, spray the negative electrode side slurry described in step (2) evenly on the positive electrode side slurry at a surface density of 18 mg / cm 2 and a thickness of 100 μm to obtain the composite modified electrolyte.

[0088] (4) First, perform a medium-temperature reaction on the composite modified electrolyte obtained in step (3). React at 50 °C for 3 hours, and then take out the electrolyte for high-temperature drying. Dry it at 100 °C for 4 hours to obtain the layered composite lithium-ion battery solid electrolyte.

[0089] Cut the obtained layered composite lithium-ion battery solid electrolyte into circular electrodes with a diameter of 16 mm as the positive electrode and solid electrolyte of the lithium-ion battery. Place it in a glove box with a water content and oxygen content both lower than 0.1 ppm and filled with an argon atmosphere for 4 h to reduce the moisture adsorbed by the electrode during transfer. Use a circular lithium sheet cut into a diameter of 16 mm as the negative electrode. Then, assemble it into a CR2032 type button battery in the glove box.

[0090] After the battery assembly is completed and aged for 12 h, perform charge and discharge tests at different potentials. The discharge specific capacity of the calcined sample after 100 cycles at a current density of 1.0C under a voltage of 2.8 - 4.3 V is 170.32 mAhg -1 . And the ionic conductivity of this sample is measured to be 2.49×10-4 S / cm.

[0091] Example 6

[0092] (1) Take 1 g of PVDF-HFP, 0.5 g of PEGDA, 0.2 g of LLZTO, 1.2 g of LiFSI, and 10 g of DME, and grind and mix them evenly to obtain the positive electrode side electrolyte slurry.

[0093] (2) Take 1 g of PVDF-HFP, 0.005 g of AIBN, 0.2 g of ZrO 2 , 1.2 g of LiFSI, and 10 g of DME, and grind and mix them evenly to obtain the negative electrode side electrolyte slurry.

[0094] (3) Mix the commercial eight-series (LiNi 0.8 Co 0.1 Mn 0.1 O 2 ) ternary cathode material with the conductive agent acetylene black (AB) and the binder polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1. Use N-methylpyrrolidone (NMP) as the solvent, place it in a small beaker, and stir and mix the materials at a speed of 800 r / min for 2 h to obtain the positive electrode slurry. Then, apply the positive electrode slurry evenly on the aluminum foil at a surface density of 5 mg / cm 2 and a thickness of 200 μm. Spray the positive electrode side slurry described in step (1) evenly on the positive electrode slurry at a surface density of 18 mg / cm 2 and a thickness of 100 μm. Then, spray the negative electrode side slurry described in step (2) evenly on the positive electrode side slurry at a surface density of 18 mg / cm 2 and a thickness of 100 μm to obtain the composite modified electrolyte.

[0095] (4) First, perform a medium-temperature reaction on the composite modified electrolyte obtained in step (3), react at 50 °C for 3 hours, and then take out the electrolyte for high-temperature drying, dry it at 100 °C for 4 hours to obtain the layered composite lithium-ion battery solid electrolyte.

[0096] Cut the obtained layered composite lithium-ion battery solid electrolyte into circular electrodes with a diameter of 16 mm as the positive electrode and solid electrolyte of the lithium-ion battery, and place it in a glove box with a water content and oxygen content both lower than 0.1 ppm and filled with an argon atmosphere for 4 h to reduce the moisture adsorbed by the electrode during the transfer process. Use a circular lithium sheet cut into a diameter of 16 mm as the negative electrode. Then, assemble it into a CR2032 type button battery in the glove box.

[0097] After the battery assembly is completed and aged for 12 h, charge-discharge tests at different potentials are carried out. The discharge specific capacity of the calcined sample after 100 cycles at a current density of 1.0 C under a voltage of 2.8 - 4.3 V is 171.22 mAhg -1 . And the ionic conductivity of this sample is measured to be 2.93×10 -4 S / cm.

[0098] The above description is only the basic explanation under the concept of the present invention, and any equivalent transformation made according to the technical solution of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for preparing a layered composite lithium-ion battery solid electrolyte, characterized in that: The following steps are involved: (1) uniformly grinding and mixing a certain ratio of lithium salt, solvent, binder, polymer monomer and oxide electrolyte to obtain a positive electrode side electrolyte slurry; (2) uniformly grinding and mixing a certain ratio of lithium salt, solvent, binder, initiator and oxide to obtain a negative electrode electrolyte slurry; (3) first spraying the positive electrode slurry described in step (1) on the existing positive electrode sheet at a certain surface density, and then applying the negative electrode slurry described in step (2) on the positive electrode slurry at a certain surface density to obtain a composite modified electrode sheet; (4) The electrode obtained in step (3) is subjected to medium-temperature reaction and high-temperature drying to obtain a layered composite lithium-ion battery solid electrolyte.

2. The method for preparing a layered composite lithium-ion battery solid electrolyte according to claim 1, characterized in that: The lithium salt in step (1) is at least one of LiFSI, LiTFSI, LiBF4, LiPF6, LiNO3, and LiClO4, the solvent is at least one of DME (ethylene glycol dimethyl ether), EGME (ethylene glycol methyl ether), and ethylene glycol diethyl ether, and the binder is PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene), PVDF-TrFE (polyvinylidene fluoride-trifluoroethylene), PVDF-CTFE (polyvinylidene fluoride-chlorotrifluoroethylene), PVDF-TFE (polyvinylidene fluoride The polymerizable monomer is at least one of PEGDA (polyethylene glycol diacrylate), PEGMA (polyethylene glycol methacrylate), PEGMEA (polyethylene glycol methyl ether acrylate), and PEGDMA (polyethylene glycol dimethacrylate); the oxide electrolyte is at least one of LLZTO (lithium lanthanum zirconium tantalum oxide), LLZO-Al (lithium lanthanum zirconium aluminum oxide), LLZO-Y (lithium lanthanum zirconium yttrium oxide), LLFTO (lithium lanthanum titanium iron oxide), and LLTO (lithium lanthanum titanium oxide).

3. The method for preparing a layered composite lithium-ion battery solid electrolyte according to claim 1, characterized in that: The mass ratio of the binder, polymer monomer, oxide electrolyte, lithium salt and solvent in step (1) is in the range of 1: (0.4-0.6): (0.15-0.25): (1.1-1.4): (9-13).

4. The method for preparing a layered composite lithium-ion battery solid electrolyte according to claim 1, characterized in that: The lithium salt described in step (2) is at least one of LiFSI, LiTFSI, LiBF4, LiPF6, LiNO3, and LiClO4, the solvent is at least one of DME (ethylene glycol dimethyl ether), EGME (ethylene glycol methyl ether), and ethylene glycol diethyl ether, the binder is at least one of PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene), PVDF-TrFE (polyvinylidene fluoride-trifluoroethylene), PVDF-CTFE (polyvinylidene fluoride-chlorotrifluoroethylene), and PVDF-TFE (polyvinylidene fluoride-tetrafluoroethylene), the initiator is at least one of AIBN (azobisisobutyronitrile), BPO (dibenzoyl peroxide), DMP-30 (2,4,6-tris(dimethylaminomethyl)phenol), and DMAP (4-dimethylaminopyridine), and the oxide is at least one of Al2O3 (aluminum oxide), ZrO2 (zirconium oxide), MgO (magnesium oxide), TiO2 (titanium oxide), SnO2 (tin oxide), and SiO2 (silicon oxide).

5. The method for preparing a layered composite lithium-ion battery solid electrolyte according to claim 1, characterized in that: The mass ratio of the binder, initiator, oxide, lithium salt and solvent in step (2) is in the range of 1:(0.004-0.006):(0.15-0.25):(1.1-1.4):(9-13).

6. The method for preparing a layered composite lithium-ion battery solid electrolyte according to claim 1, characterized in that: The active material in the existing positive electrode sheet in step (3) is LiNi x Co y Mn 1-x-y O2, (x, y, 1-xy are all between 0 and 1), and the mass content of the positive electrode active material is 75%-95%, and the coating surface density is 1-10 mg / cm 2 , thickness is 180-200μm.

7. The method for preparing a layered composite lithium-ion battery solid electrolyte according to claim 1, characterized in that: The surface density of the slurry sprayed in step (3) is 12-18 mg / cm 2 , the slurry thickness is 80-120μm.

8. The method for preparing a layered composite lithium-ion battery solid electrolyte according to claim 1, characterized in that: The temperature of the medium temperature reaction in step (4) is 40-60°C, the time of the medium temperature reaction is 2-5 hours, the temperature of the high temperature drying is 90-120°C, and the time of the high temperature drying is 3-6 hours.

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