A semi-solid battery composite separator and its preparation method

Abstract

This invention relates to the field of battery separators, and discloses a semi-solid-state battery composite separator and its preparation method, comprising a base film and a nanoparticle-reinforced PEO layer and an LATP layer sequentially coated on the surface of the base film; the raw materials for the nanoparticle-reinforced PEO layer include ZrO2@polyetheramine core-shell nanoparticles and PEO in a mass ratio of 1~3:1; the ZrO2@polyetheramine core-shell nanoparticles are prepared by a solvent-free nanofluidic method, with ZrO2 nanoparticles as the core and polyetheramine as the shell, and the mass ratio of ZrO2 nanoparticles to polyetheramine is 1:5~20. This invention, by sequentially coating the separator surface with an LATP layer and a PEO layer reinforced by ZrO2@polyetheramine nanoparticles, can effectively improve the ionic conductivity of the polyethylene separator, reduce the amount of electrolyte used, and also improve the heat resistance and safety stability of the base film.

Description

Technical Field

[0001] This invention relates to the field of battery separator technology, and in particular to a semi-solid battery composite separator and its preparation method. Background Technology

[0002] With the rapid development of new energy vehicles and portable electronic devices, people have placed higher demands on battery performance, such as longer lifespan, stronger safety performance, and higher energy density. Safety performance is often the top priority, as lithium batteries are closely related to human life. Spontaneous combustion or explosion could pose a significant risk to personal safety and property damage. In traditional liquid lithium batteries, the presence of a large amount of flammable electrolyte is the primary potential safety factor. Therefore, the emergence of semi-solid-state batteries with lower electrolyte usage, and even all-solid-state batteries without electrolyte, can greatly improve the safety performance of lithium-ion batteries. Semi-solid-state batteries, as a transitional technology between liquid and all-solid-state batteries, are widely favored because they are compatible with both existing and new technologies.

[0003] Because semi-solid batteries typically incorporate solid electrolytes into their separators, the ionic conductivity of the separator is improved, thereby reducing the amount of electrolyte used. This significantly enhances the safety performance of lithium batteries. For example, patent CN119944220A discloses a composite separator and its preparation method, as well as a semi-solid battery. The composite separator includes a non-woven porous substrate and a composite solid electrolyte coating filling the pores of the non-woven porous substrate. Polymer electrolytes, such as polyethylene oxide (PEO), exhibit good conductivity to a certain extent, but their high crystallinity often leads to decreased mechanical properties and makes them susceptible to lithium dendrite puncture at high temperatures, causing safety issues. Oxide electrolytes, when used alone, suffer from difficult-to-solve interface problems with the electrodes, resulting in a decline in lithium battery performance.

[0004] Therefore, it is essential to develop a semi-solid battery composite separator that can balance safety and high lithium-ion transport efficiency. Summary of the Invention

[0005] This invention aims to overcome the aforementioned problems of existing semi-solid battery separators and provides a semi-solid battery composite separator and its preparation method. By sequentially coating the separator surface with an LATP layer and a PEO layer reinforced by ZrO2@polyetheramine nanoparticles, the ionic conductivity of the polyethylene separator can be effectively improved, the amount of electrolyte used can be reduced, and the heat resistance and safety stability of the base film can also be improved.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A semi-solid battery composite separator includes a base film and a nanoparticle-reinforced PEO layer and an LATP layer sequentially coated on the surface of the base film.

[0008] The raw materials for the nanoparticle-reinforced PEO layer include ZrO2@polyetheramine core-shell nanoparticles and PEO in a mass ratio of 1 to 3:1; the ZrO2@polyetheramine core-shell nanoparticles are prepared by a solvent-free nanofluidic method, with ZrO2 nanoparticles as the core and polyetheramine as the shell, and the mass ratio of ZrO2 nanoparticles to polyetheramine is 1:5 to 20.

[0009] This invention sequentially deposits a nanoparticle-reinforced PEO layer and an LATP layer on a base membrane. LATP, as an oxide solid electrolyte, significantly improves the ionic conductivity of the membrane when coated on the composite separator surface, reducing electrolyte consumption and enhancing the safety of the semi-solid-state battery. The PEO in the PEO layer, as a polymer electrolyte, effectively improves the ionic conductivity of the base membrane. Adding ZrO2@polyetheramine core-shell nanoparticles to reinforce PEO, with the polyetheramine on the shell exhibiting good compatibility with PEO, facilitates the uniform dispersion of ZrO2 composite particles in the PEO slurry, thereby significantly reducing the crystallinity of PEO and increasing its mechanical strength, which is beneficial for enhancing the cycle stability and safety of the semi-solid-state battery. Furthermore, polyetheramine, as a polymer containing oxygen and nitrogen heteroatoms, possesses excellent electrical conductivity; its introduction into the separator contributes to improving the ionic conductivity of the semi-solid-state composite separator. Coating nano-ZrO2 and nano-LATP as inorganic particles onto the base membrane also effectively enhances the base membrane's resistance to thermal shrinkage and improves its heat resistance.

[0010] Preferably, the ZrO2 nanoparticles in the ZrO2@polyetheramine core-shell nanoparticles have a particle size of 50~200nm.

[0011] Preferably, the base film is a polyethylene base film with a thickness of 10~30μm and a porosity of 70~80%.

[0012] Preferably, the thickness of the nanoparticle-reinforced PEO layer is 3~5μm; and the thickness of the LATP layer is 2~3μm.

[0013] The present invention also provides a method for preparing the above-mentioned semi-solid battery composite separator, comprising the following steps:

[0014] (1) ZrO2@polyetheramine core-shell nanoparticles were prepared by a solvent-free nanofluidic method;

[0015] (2) ZrO2@polyetheramine core-shell nanoparticles, PEO and solvent are mixed to form a coating slurry, which is then coated on the surface of the base film and dried to obtain a nanoparticle-reinforced PEO layer.

[0016] (3) Mix LATP particles with solvent to make a coating slurry, coat it on the surface of the nanoparticle-reinforced PEO layer, and dry it to obtain the LATP layer.

[0017] (4) The composite membrane is pressed to obtain the semi-solid battery composite membrane.

[0018] Preferably, the preparation method of ZrO2@polyetheramine core-shell nanoparticles in step (1) includes the following steps:

[0019] A) Mix polyetheramine, silane coupling agent and solvent evenly to obtain mixture A;

[0020] B) Add ZrO2 nanoparticles to mixture A and stir until homogeneous to obtain mixture B;

[0021] C) The mixture B is placed in a dialysis bag for dialysis, then dried to remove the solvent, to obtain the ZrO2@polyetheramine core-shell nanoparticles.

[0022] Preferably, in step A), the molar ratio of silane coupling agent to polyetheramine is 1~2:1; in step C), the molecular weight cutoff of the dialysis bag is 3000~8000, and the dialysis time is 24~60h.

[0023] Preferably, the polyetheramine mentioned in step A) is one or more of polyether monoamine M1000, polyether monoamine M2070, polyether diamine D230, and polyether diamine D400; the silane coupling agent is one or more of KH550 and KH560; and the solvent is one or more of methanol, ethanol, ethylene glycol, and isopropanol.

[0024] Preferably, the solvent used in steps (2) and (3) is anhydrous acetonitrile; the drying temperature is 50~70℃.

[0025] Preferably, the pressure during pressing in step (4) is 10~20MPa and the holding time is 1~2h.

[0026] Therefore, the present invention has the following beneficial effects:

[0027] (1) Adding ZrO2@polyetheramine core-shell nanoparticles to enhance the PEO layer can significantly reduce the crystallinity of PEO, improve the peristalsis of PEO segments, and increase the safety and stability of the battery.

[0028] (2) By introducing solid electrolyte LATP, polymer electrolyte PEO and conductive polymer polyetheramine, the ionic conductivity of the base film can be effectively improved and the amount of electrolyte used can be reduced.

[0029] (3) Nano ZrO2 and nano LATP are coated onto the base film as inorganic particles, which can effectively enhance the base film's ability to resist thermal shrinkage and improve the heat resistance of the base film. Detailed Implementation

[0030] The present invention will be further described below with reference to specific embodiments.

[0031] In this invention, unless otherwise specified, all equipment and raw materials are available from the market or commonly used in the industry. The methods in the following embodiments are conventional methods in the field unless otherwise specified.

[0032] General Implementation Examples:

[0033] A semi-solid battery composite separator includes a base film and a nanoparticle-reinforced PEO layer and an LATP layer sequentially coated on the surface of the base film.

[0034] The raw materials for the nanoparticle-reinforced PEO layer include ZrO2@polyetheramine core-shell nanoparticles and PEO in a mass ratio of 1 to 3:1; the ZrO2@polyetheramine core-shell nanoparticles are prepared by a solvent-free nanofluidic method, with ZrO2 nanoparticles as the core and polyetheramine as the shell, and the mass ratio of ZrO2 nanoparticles to polyetheramine is 1:5 to 20.

[0035] In one specific embodiment, the ZrO2 nanoparticles in the ZrO2@polyetheramine core-shell nanoparticles have a particle size of 50~200nm.

[0036] In one specific embodiment, the base film is a polyethylene base film with a thickness of 10~30μm and a porosity of 70~80%.

[0037] In one specific embodiment, the thickness of the nanoparticle-reinforced PEO layer is 3~5μm; the thickness of the LATP layer is 2~3μm.

[0038] The preparation method of the above-mentioned semi-solid battery composite separator includes the following steps:

[0039] (1) ZrO2@polyetheramine core-shell nanoparticles were prepared by a solvent-free nanofluidic method;

[0040] (2) ZrO2@polyetheramine core-shell nanoparticles, PEO and solvent are mixed to form a coating slurry, which is then coated on the surface of the base film and dried to obtain a nanoparticle-reinforced PEO layer.

[0041] (3) Mix LATP particles with solvent to make a coating slurry, coat it on the surface of the nanoparticle-reinforced PEO layer, and dry it to obtain the LATP layer.

[0042] (4) The composite membrane is pressed to obtain the semi-solid battery composite membrane.

[0043] As one specific implementation method, the preparation method of ZrO2@polyetheramine core-shell nanoparticles in step (1) includes the following steps:

[0044] A) Mix polyetheramine, silane coupling agent and solvent evenly to obtain mixture A;

[0045] B) Add ZrO2 nanoparticles to mixture A and stir until homogeneous to obtain mixture B;

[0046] C) The mixture B is placed in a dialysis bag for dialysis, then dried to remove the solvent, to obtain the ZrO2@polyetheramine core-shell nanoparticles.

[0047] In one specific implementation, the molar ratio of silane coupling agent to polyetheramine in step A) is 1~2:1.

[0048] In one specific embodiment, the polyetheramine mentioned in step A) is one or more of polyether monoamine M1000, polyether monoamine M2070, polyether diamine D230, and polyether diamine D400; the silane coupling agent is one or more of KH550 and KH560; and the solvent is one or more of methanol, ethanol, ethylene glycol, and isopropanol.

[0049] In one specific implementation, in step A), the polyetheramine, silane coupling agent and solvent are mixed and stirred at 40-50°C for 18-24 hours to obtain mixture A.

[0050] In one specific implementation, the temperature during stirring in step B) is 25~30℃, and the stirring time is 18~24h.

[0051] In one specific implementation, in step C), the molecular weight cutoff of the dialysis bag is 3000~8000, the dialysis time is 24~60h, and the dialysis temperature is room temperature.

[0052] In one specific implementation, the solvent in steps (2) and (3) is anhydrous acetonitrile; the drying temperature is 50~70℃.

[0053] In one specific implementation, the particle size of the LATP particles in step (3) is 50~500nm.

[0054] In one specific implementation, the pressure during pressing in step (4) is 10~20MPa, and the holding time is 1~2h.

[0055] Example 1:

[0056] A method for preparing a semi-solid battery composite separator includes the following steps:

[0057] (1) Preparation of ZrO2@polyetheramine core-shell nanoparticles by solvent-free nanofluid method:

[0058] A) Add 200g of polyetheramine M1000 and 47.2g of silane coupling agent KH560 to 500mL of methanol, and reflux under condensation and magnetic stirring at 40℃ and 500rpm for 18h to obtain mixture A.

[0059] B) Add 20g of ZrO2 nanoparticles (D50=50nm) to the mixture A in small amounts several times, and stir magnetically for 18h at 25℃ and 200rpm to obtain mixture B;

[0060] C) Pour mixture B into a dialysis bag with a molecular weight cutoff of 4000, and dialyze the dialysis bag in deionized water at room temperature for 30 hours, changing the deionized water every 6 hours during the process.

[0061] D) After dialysis, the mixture is poured out and dried at 60°C for 1 hour to remove the solvent, resulting in a viscous, flowable liquid, which is ZrO2@polyetheramine core-shell nanoparticles.

[0062] (2) PEO powder (Sumitomo PEO-8 from Japan) was ground and added to anhydrous acetonitrile in small amounts several times. The mixture was mechanically stirred at 1500 rpm for 2 hours. Then, ZrO2@polyetheramine core-shell nanoparticles were added to the mixture at a mass ratio of ZrO2 to PEO of 1:1. The mixture was mechanically stirred at 500 rpm for 1 hour to obtain a uniform PEO-ZrO2 composite particle slurry. The solid content of the slurry was adjusted to 30 wt%.

[0063] (3) The PEO-ZrO2 composite particle slurry was uniformly coated on the surface of the PE base film (thickness 12μm, porosity 80%) using a wire rod, and dried at 60℃ to obtain a semi-finished diaphragm. The coating thickness was controlled to be 2μm.

[0064] (4) The LATP nanoparticles (D50=200nm) were uniformly dispersed in anhydrous acetonitrile, and the solid content was adjusted to 40wt%. Then, the LATP slurry was uniformly coated on the surface of the semi-finished separator with a wire rod and dried at 60°C. The thickness of the LATP layer was controlled to be 3μm. Then, the separator was pressed at 15MPa for 1h using a hydraulic press to obtain the semi-solid battery composite separator.

[0065] Example 2:

[0066] A method for preparing a semi-solid battery composite separator includes the following steps:

[0067] (1) Preparation of ZrO2@polyetheramine core-shell nanoparticles by solvent-free nanofluid method:

[0068] A) Add 400g of polyetheramine M2070 and 44.2g of silane coupling agent KH550 to 500mL of methanol, and reflux under 50℃ and 500rpm for 24h with magnetic stirring to obtain mixture A.

[0069] B) Add 20g of ZrO2 nanoparticles (D50=50nm) to the mixture A in small amounts several times, and stir magnetically for 24h at 25℃ and 200rpm to obtain mixture B;

[0070] C) Pour mixture B into a dialysis bag with a molecular weight cutoff of 5000, and dialyze the dialysis bag in deionized water at room temperature for 24 hours, changing the deionized water every 6 hours during the process.

[0071] D) After dialysis, the mixture is poured out and dried at 60°C for 1 hour to remove the solvent, resulting in a viscous, flowable liquid, which is ZrO2@polyetheramine core-shell nanoparticles.

[0072] (2) PEO powder (Sumitomo PEO-8 from Japan) was ground and added to anhydrous acetonitrile in small amounts several times. The mixture was mechanically stirred at 1500 rpm for 2 hours. Then, ZrO2@polyetheramine core-shell nanoparticles were added to the mixture at a mass ratio of ZrO2 to PEO of 2:1. The mixture was mechanically stirred at 500 rpm for 1 hour to obtain a uniform PEO-ZrO2 composite particle slurry. The solid content of the slurry was adjusted to 30 wt%.

[0073] (3) The PEO-ZrO2 composite particle slurry was uniformly coated on the surface of the PE base film (thickness 12μm, porosity 80%) using a wire rod, and dried at 60℃ to obtain a semi-finished diaphragm. The coating thickness was controlled to be 2μm.

[0074] (4) The LATP nanoparticles (D50=200nm) were uniformly dispersed in anhydrous acetonitrile, and the solid content was adjusted to 40wt%. Then, the LATP slurry was uniformly coated on the surface of the semi-finished separator with a wire rod and dried at 60°C. The thickness of the LATP layer was controlled to be 4μm. Then, the separator was pressed at 15MPa for 1h using a hydraulic press to obtain the semi-solid battery composite separator.

[0075] Example 3:

[0076] A method for preparing a semi-solid battery composite separator includes the following steps:

[0077] (1) Preparation of ZrO2@polyetheramine core-shell nanoparticles by solvent-free nanofluid method:

[0078] A) Add 46g of polyetheramine D230 and 94.4g of silane coupling agent KH560 to 500mL of ethanol, and reflux under condensation and magnetic stirring at 50℃ and 500rpm for 24h to obtain mixture A.

[0079] B) Add 4.6g of ZrO2 nanoparticles (D50=50nm) to the mixture A in small amounts several times, and stir magnetically for 24h at 30℃ and 200rpm to obtain mixture B;

[0080] C) Pour mixture B into a dialysis bag with a molecular weight cutoff of 6000, and dialyze the dialysis bag in deionized water at room temperature for 48 hours, changing the deionized water every 6 hours during the process.

[0081] D) After dialysis, the mixture is poured out and dried at 60°C for 1 hour to remove the solvent, resulting in a viscous, flowable liquid, which is ZrO2@polyetheramine core-shell nanoparticles.

[0082] (2) PEO powder (Sumitomo PEO-8 from Japan) was ground and added to anhydrous acetonitrile in small amounts several times. The mixture was mechanically stirred at 1500 rpm for 2 hours. Then, ZrO2@polyetheramine core-shell nanoparticles were added to the mixture at a mass ratio of ZrO2 to PEO of 3:1. The mixture was mechanically stirred at 500 rpm for 1 hour to obtain a uniform PEO-ZrO2 composite particle slurry. The solid content of the slurry was adjusted to 30 wt%.

[0083] (3) The PEO-ZrO2 composite particle slurry was uniformly coated on the surface of the PE base film (thickness 12μm, porosity 80%) using a wire rod, and dried at 60℃ to obtain a semi-finished diaphragm. The coating thickness was controlled to be 3μm.

[0084] (4) The LATP nanoparticles (D50=200nm) were uniformly dispersed in anhydrous acetonitrile, and the solid content was adjusted to 40wt%. Then, the LATP slurry was uniformly coated on the surface of the semi-finished separator with a wire rod and dried at 60°C. The thickness of the LATP layer was controlled to be 4μm. Then, the separator was pressed at 15MPa for 1h using a hydraulic press to obtain the semi-solid battery composite separator.

[0085] Example 4:

[0086] A method for preparing a semi-solid battery composite separator includes the following steps:

[0087] (1) Preparation of ZrO2@polyetheramine core-shell nanoparticles by solvent-free nanofluid method:

[0088] A) Add 46g of polyetheramine D230 and 88.4g of silane coupling agent KH550 to 500mL of ethanol, and reflux under condensation and magnetic stirring at 45℃ and 500rpm for 20h to obtain mixture A;

[0089] B) Add 9.2g of ZrO2 nanoparticles (D50=50nm) to the mixture A in small amounts several times, and stir magnetically for 24h at 25℃ and 200rpm to obtain mixture B;

[0090] C) Pour mixture B into a dialysis bag with a molecular weight cutoff of 4000, and dialyze the dialysis bag in deionized water at room temperature for 48 hours, changing the deionized water every 6 hours during the process.

[0091] D) After dialysis, the mixture is poured out and dried at 60°C for 1 hour to remove the solvent, resulting in a viscous, flowable liquid, which is ZrO2@polyetheramine core-shell nanoparticles.

[0092] (2) PEO powder (Sumitomo PEO-8 from Japan) was ground and added to anhydrous acetonitrile in small amounts several times. The mixture was mechanically stirred at 1500 rpm for 2 hours. Then, ZrO2@polyetheramine core-shell nanoparticles were added to the mixture at a mass ratio of ZrO2 to PEO of 3:1. The mixture was mechanically stirred at 500 rpm for 1 hour to obtain a uniform PEO-ZrO2 composite particle slurry. The solid content of the slurry was adjusted to 30 wt%.

[0093] (3) The PEO-ZrO2 composite particle slurry was uniformly coated on the surface of the PE base film (thickness 12μm, porosity 80%) using a wire rod, and dried at 60℃ to obtain a semi-finished diaphragm. The coating thickness was controlled to be 3μm.

[0094] (4) The LATP nanoparticles (D50=200nm) were uniformly dispersed in anhydrous acetonitrile, and the solid content was adjusted to 40wt%. Then, the LATP slurry was uniformly coated on the surface of the semi-finished separator with a wire rod and dried at 60°C. The thickness of the LATP layer was controlled to be 5μm. Then, the separator was pressed at 15MPa for 1h using a hydraulic press to obtain the semi-solid battery composite separator.

[0095] Example 5:

[0096] A method for preparing a semi-solid battery composite separator includes the following steps:

[0097] (1) Preparation of ZrO2@polyetheramine core-shell nanoparticles by solvent-free nanofluid method:

[0098] A) Add 80g of polyetheramine D400 and 94.4g of silane coupling agent KH550 to 500mL of isopropanol, and reflux under condensation and magnetic stirring at 40℃ and 500rpm for 18h to obtain mixture A.

[0099] B) Add 4g of ZrO2 nanoparticles (D50=50nm) to the mixture A in small amounts several times, and stir magnetically for 18h at 25℃ and 200rpm to obtain mixture B;

[0100] C) Pour mixture B into a dialysis bag with a molecular weight cutoff of 3000, and dialyze the dialysis bag in deionized water at room temperature for 48 hours, changing the deionized water every 6 hours during the process.

[0101] D) After dialysis, the mixture is poured out and dried at 60°C for 1 hour to remove the solvent, resulting in a viscous, flowable liquid, which is ZrO2@polyetheramine core-shell nanoparticles.

[0102] (2) PEO powder (Sumitomo PEO-8 from Japan) was ground and added to anhydrous acetonitrile in small amounts several times. The mixture was mechanically stirred at 1500 rpm for 2 hours. Then, ZrO2@polyetheramine core-shell nanoparticles were added to the mixture at a mass ratio of ZrO2 to PEO of 3:1. The mixture was mechanically stirred at 500 rpm for 1 hour to obtain a uniform PEO-ZrO2 composite particle slurry. The solid content of the slurry was adjusted to 30 wt%.

[0103] (3) The PEO-ZrO2 composite particle slurry was uniformly coated on the surface of the PE base film (thickness 12μm, porosity 80%) using a wire rod, and dried at 60℃ to obtain a semi-finished diaphragm. The coating thickness was controlled to be 2μm.

[0104] (4) The LATP nanoparticles (D50=200nm) were uniformly dispersed in anhydrous acetonitrile, and the solid content was adjusted to 40wt%. Then, the LATP slurry was uniformly coated on the surface of the semi-finished separator with a wire rod and dried at 60°C. The thickness of the LATP layer was controlled to be 5μm. Then, the separator was pressed at 15MPa for 1h using a hydraulic press to obtain the semi-solid battery composite separator.

[0105] Example 6:

[0106] A method for preparing a semi-solid battery composite separator includes the following steps:

[0107] (1) Preparation of ZrO2@polyetheramine core-shell nanoparticles by solvent-free nanofluid method:

[0108] A) Add 46g of polyetheramine D230 and 94.4g of silane coupling agent KH550 to 500mL of ethanol, and reflux under condensation and magnetic stirring at 50℃ and 500rpm for 30h to obtain mixture A.

[0109] B) Add 3g of ZrO2 nanoparticles (D50=50nm) to the mixture A in small amounts several times, and stir magnetically for 24h at 30℃ and 200rpm to obtain mixture B;

[0110] C) Pour mixture B into a dialysis bag with a molecular weight cutoff of 6000, and dialyze the dialysis bag in deionized water at room temperature for 48 hours, changing the deionized water every 6 hours during the process.

[0111] D) After dialysis, the mixture is poured out and dried at 60°C for 1 hour to remove the solvent, resulting in a viscous, flowable liquid, which is ZrO2@polyetheramine core-shell nanoparticles.

[0112] (2) PEO powder (Sumitomo PEO-8 from Japan) was ground and added to anhydrous acetonitrile in small amounts several times. The mixture was mechanically stirred at 1500 rpm for 2 hours. Then, ZrO2@polyetheramine core-shell nanoparticles were added to the mixture at a mass ratio of ZrO2 to PEO of 2:1. The mixture was mechanically stirred at 500 rpm for 1 hour to obtain a uniform PEO-ZrO2 composite particle slurry. The solid content of the slurry was adjusted to 30 wt%.

[0113] (3) The PEO-ZrO2 composite particle slurry was uniformly coated on the surface of the PE base film (thickness 12μm, porosity 80%) using a wire rod, and dried at 60℃ to obtain a semi-finished diaphragm. The coating thickness was controlled to be 2μm.

[0114] (4) The LATP nanoparticles (D50=200nm) were uniformly dispersed in anhydrous acetonitrile, and the solid content was adjusted to 40wt%. Then, the LATP slurry was uniformly coated on the surface of the semi-finished separator with a wire rod and dried at 60°C. The thickness of the LATP layer was controlled to be 3μm. Then, the separator was pressed at 15MPa for 1h using a hydraulic press to obtain the semi-solid battery composite separator.

[0115] Example 7:

[0116] A method for preparing a semi-solid battery composite separator includes the following steps:

[0117] (1) Preparation of ZrO2@polyetheramine core-shell nanoparticles by solvent-free nanofluid method:

[0118] A) Add 80g of polyetheramine D400 and 94.4g of silane coupling agent KH560 to 500mL of ethanol, and reflux under condensation and magnetic stirring at 50℃ and 500rpm for 24h to obtain mixture A.

[0119] B) Add 5.3g of ZrO2 nanoparticles (D50=50nm) to the mixture A in small amounts several times, and stir magnetically for 24h at 30℃ and 200rpm to obtain mixture B;

[0120] C) Pour mixture B into a dialysis bag with a molecular weight cutoff of 8000, and dialyze the dialysis bag in deionized water at room temperature for 60 hours, changing the deionized water every 6 hours during the process.

[0121] D) After dialysis, the mixture is poured out and dried at 60°C for 1 hour to remove the solvent, resulting in a viscous, flowable liquid, which is ZrO2@polyetheramine core-shell nanoparticles.

[0122] (2) PEO powder (Sumitomo PEO-8 from Japan) was ground and added to anhydrous acetonitrile in small amounts several times. The mixture was mechanically stirred at 1500 rpm for 2 hours. Then, ZrO2@polyetheramine core-shell nanoparticles were added to the mixture at a mass ratio of ZrO2 to PEO of 1:1. The mixture was mechanically stirred at 500 rpm for 1 hour to obtain a uniform PEO-ZrO2 composite particle slurry. The solid content of the slurry was adjusted to 30 wt%.

[0123] (3) The PEO-ZrO2 composite particle slurry was uniformly coated on the surface of the PE base film (thickness 12μm, porosity 80%) using a wire rod, and dried at 60℃ to obtain a semi-finished diaphragm. The coating thickness was controlled to be 3μm.

[0124] (4) The LATP nanoparticles (D50=200nm) were uniformly dispersed in anhydrous acetonitrile, and the solid content was adjusted to 40wt%. Then, the LATP slurry was uniformly coated on the surface of the semi-finished separator with a wire rod and dried at 60°C. The thickness of the LATP layer was controlled to be 3μm. Then, the separator was pressed at 15MPa for 1h using a hydraulic press to obtain the semi-solid battery composite separator.

[0125] Comparative Example 1 (without ZrO2@polyetheramine core-shell nanoparticles):

[0126] A method for preparing a semi-solid battery composite separator includes the following steps:

[0127] (1) PEO powder (Sumitomo PEO-8 from Japan) was ground and added to anhydrous acetonitrile in small amounts several times. The mixture was mechanically stirred at 1500 rpm for 2 hours to obtain a uniform PEO slurry, and its solid content was adjusted to 30 wt%.

[0128] (2) The PEO slurry is uniformly coated on the surface of the PE base film (thickness 12μm, porosity 80%) using a wire rod, and dried at 60℃ to obtain a semi-finished diaphragm. The coating thickness is controlled to be 3μm.

[0129] (3) The LATP nanoparticles (D50=200nm) were uniformly dispersed in anhydrous acetonitrile, and the solid content was adjusted to 40wt%. Then, the LATP slurry was uniformly coated on the surface of the semi-finished separator with a wire rod and dried at 60°C. The thickness of the LATP layer was controlled to be 4μm. Then, the separator was pressed at 15MPa for 1h using a hydraulic press to obtain the semi-solid battery composite separator.

[0130] Comparative Example 2 (ZrO2 is not coated with polyetheramine):

[0131] A method for preparing a semi-solid battery composite separator includes the following steps:

[0132] (1) PEO powder (Sumitomo PEO-8 from Japan) was ground and added to anhydrous acetonitrile in small amounts several times. The mixture was mechanically stirred at 1500 rpm for 2 hours. Then, ZrO2 nanoparticles (D50=50nm) were added to the mixture at a mass ratio of ZrO2 to PEO of 3:1. The mixture was mechanically stirred at 500 rpm for 1 hour to obtain a uniform PEO-ZrO2 composite slurry. The solid content of the slurry was adjusted to 30 wt%.

[0133] (2) The PEO-ZrO2 composite slurry was uniformly coated on the surface of the PE base film (thickness 12μm, porosity 80%) using a wire rod, and dried at 60℃ to obtain a semi-finished diaphragm. The coating thickness was controlled to be 3μm.

[0134] (3) The LATP nanoparticles (D50=200nm) were uniformly dispersed in anhydrous acetonitrile, and the solid content was adjusted to 40wt%. Then, the LATP slurry was uniformly coated on the surface of the semi-finished separator with a wire rod and dried at 60°C. The thickness of the LATP layer was controlled to be 4μm. Then, the separator was pressed at 15MPa for 1h using a hydraulic press to obtain the semi-solid battery composite separator.

[0135] Comparative Example 3 (without LATP layer):

[0136] A method for preparing a semi-solid battery composite separator includes the following steps:

[0137] (1) Preparation of ZrO2@polyetheramine core-shell nanoparticles by solvent-free nanofluid method: The method is the same as in Example 4;

[0138] (2) PEO powder (Sumitomo PEO-8 from Japan) was ground and added to anhydrous acetonitrile in small amounts several times. The mixture was mechanically stirred at 1500 rpm for 2 hours. Then, ZrO2@polyetheramine core-shell nanoparticles were added to the mixture at a mass ratio of ZrO2 to PEO of 3:1. The mixture was mechanically stirred at 500 rpm for 1 hour to obtain a uniform PEO-ZrO2 composite particle slurry. The solid content of the slurry was adjusted to 30 wt%.

[0139] (3) The PEO-ZrO2 composite particle slurry is uniformly coated on the surface of the PE base film (thickness 12μm, porosity 80%) using a wire rod. After drying at 60℃, a semi-finished separator is obtained, and its coating thickness is controlled at 3μm. Then, the separator is pressed at 15MPa for 1h using a hydraulic press to obtain the semi-solid battery composite separator.

[0140] The performance of the composite membranes obtained in the above embodiments and comparative examples was tested, and the results are shown in Table 1.

[0141] Table 1: Performance Test Results of Composite Separator

[0142]

[0143] The test conditions for heat shrinkage rate were: 105℃, 1h.

[0144] As can be seen from Table 1, the composite membranes prepared by the method of the present invention in Examples 1 to 7 have high ionic conductivity and puncture strength, and low thermal shrinkage. They can effectively improve the ionic conductivity of polyethylene-based membranes, reduce the amount of electrolyte used, and also improve the heat resistance and safety stability of the base membrane.

[0145] In Comparative Example 1, no ZrO2@polyetheramine core-shell nanoparticles were added to the PEO layer for reinforcement. As a result, the mechanical properties of the membrane were significantly reduced compared to Example 3, and it was easily punctured by lithium dendrites under high temperature conditions, which could lead to safety issues.

[0146] In Comparative Example 2, ZrO2 nanoparticles were directly used to reinforce the PEO layer without coating it with polyetheramine. The poor compatibility between ZrO2 nanoparticles and PEO hindered the uniform dispersion of ZrO2 nanoparticles in the PEO layer. The heat resistance and safety stability of the membrane decreased compared to Example 3. Furthermore, the lack of coating with the conductive polymer polyetheramine resulted in a decrease in the ionic conductivity of the membrane compared to Example 3.

[0147] In Comparative Example 3, the LATP layer was not provided, and the ionic conductivity and heat resistance of the membrane decreased significantly compared with those in Example 4.

Claims

1. A semi-solid-state battery composite separator, characterized in that, It includes a base film and a nanoparticle-reinforced PEO layer and an LATP layer sequentially coated on the surface of the base film; The raw materials for the nanoparticle-reinforced PEO layer include ZrO2@polyetheramine core-shell nanoparticles and PEO in a mass ratio of 1 to 3:1; the ZrO2@polyetheramine core-shell nanoparticles are prepared by a solvent-free nanofluidic method, with ZrO2 nanoparticles as the core and polyetheramine as the shell, and the mass ratio of ZrO2 nanoparticles to polyetheramine is 1:5 to 20.

2. The semi-solid battery composite separator according to claim 1, characterized in that, The ZrO2 nanoparticles in the ZrO2@polyetheramine core-shell nanoparticles have a particle size of 50~200nm.

3. The semi-solid battery composite separator according to claim 1, characterized in that, The base film is a polyethylene base film with a thickness of 10~30μm and a porosity of 70~80%.

4. The semi-solid battery composite separator according to claim 1 or 3, characterized in that, The thickness of the nanoparticle-reinforced PEO layer is 3~5μm; the thickness of the LATP layer is 2~3μm.

5. A method for preparing a semi-solid-state battery composite separator as described in any one of claims 1 to 4, characterized in that, Includes the following steps: (1) ZrO2@polyetheramine core-shell nanoparticles were prepared by a solvent-free nanofluidic method; (2) ZrO2@polyetheramine core-shell nanoparticles, PEO and solvent are mixed to form a coating slurry, which is then coated on the surface of the base film and dried to obtain a nanoparticle-reinforced PEO layer. (3) Mix LATP particles with solvent to make a coating slurry, coat it on the surface of the nanoparticle-reinforced PEO layer, and dry it to obtain the LATP layer. (4) The composite membrane is pressed to obtain the semi-solid battery composite membrane.

6. The method for preparing the semi-solid-state battery composite separator according to claim 5, characterized in that, The preparation method of ZrO2@polyetheramine core-shell nanoparticles in step (1) includes the following steps: A) Mix polyetheramine, silane coupling agent and solvent evenly to obtain mixture A; B) Add ZrO2 nanoparticles to mixture A and stir until homogeneous to obtain mixture B; C) The mixture B is placed in a dialysis bag for dialysis, then dried to remove the solvent, to obtain the ZrO2@polyetheramine core-shell nanoparticles.

7. The method for preparing the semi-solid-state battery composite separator according to claim 6, characterized in that, In step A), the molar ratio of silane coupling agent to polyetheramine is 1~2:1; in step C), the molecular weight cutoff of the dialysis bag is 3000~8000, and the dialysis time is 24~60h.

8. The method for preparing the semi-solid-state battery composite separator according to claim 6 or 7, characterized in that, The polyetheramine mentioned in step A) is one or more of polyether monoamine M1000, polyether monoamine M2070, polyether diamine D230, and polyether diamine D400; the silane coupling agent is one or more of KH550 and KH560; and the solvent is one or more of methanol, ethanol, ethylene glycol, and isopropanol.

9. The method for preparing the semi-solid battery composite separator according to claim 5, characterized in that, The solvent mentioned in steps (2) and (3) is anhydrous acetonitrile; the drying temperature is 50~70℃.

10. The method for preparing the semi-solid-state battery composite separator according to claim 5, characterized in that, In step (4), the pressure during pressing is 10~20MPa, and the holding time is 1~2h.

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