Solid-state-like lithium battery and preparation method thereof

Abstract

The invention belongs to the technical field of batteries, and relates to a solid-state-like lithium battery and a preparation method thereof.The preparation method comprises the steps that a positive plate, a negative plate and a diaphragm are assembled into a battery cell, a precursor solution is injected for a polymerization reaction, and the solid-state-like lithium battery is prepared; the preparation method of the positive plate comprises the following steps: providing a positive plate active material, a positive conductive agent and a positive binder, and dispersing in a solvent to prepare positive slurry; coating the positive electrode slurry on a positive electrode current collector to prepare a positive electrode plate; the positive current collector is an aluminum foil of which one surface is coated with an insulating layer or a composite aluminum foil of which one surface is doped with a solid electrolyte; the preparation method of the negative plate comprises the following steps: dispersing a negative plate active material, a negative conductive agent and a negative binder in a solvent to prepare negative slurry; coating a negative electrode current collector with the negative electrode slurry to prepare a negative electrode plate; the precursor solution accounts for 1%-5% of the mass of the solid-state-like lithium battery and comprises a polymerizable monomer, a thermal initiator and a lithium salt. According to the invention, the solid-state-like lithium battery with high safety, wide temperature range and high energy density can be prepared.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to a solid-state-like lithium battery and its preparation method. Background Technology

[0002] Traditional liquid lithium-ion batteries contain a large amount (usually accounting for 10%-20% of the total battery mass) of flammable organic electrolyte, which is prone to membrane collapse and internal short circuits under mechanical abuse such as puncture and extrusion, ultimately leading to thermal runaway. In addition, their operating temperature range is narrow (usually -20℃ to 60℃). At low temperatures, the electrolyte viscosity increases sharply, which leads to ion transport obstruction and severe capacity decay (capacity retention rate is often <50% at <-20℃). At high temperatures, the side reactions at the electrolyte and electrode interface are aggravated, and the cycle life drops sharply (capacity retention rate is often <75% after 500 cycles at >60℃).

[0003] While all-solid-state batteries address safety concerns by replacing liquid electrolytes with solid electrolytes, they also suffer from high solid-solid interfacial impedance (typically much higher than liquid systems, reaching up to 1000 Ω·cm²) and low ionic conductivity (often <10 at room temperature). -4 Problems such as low S / cm and high manufacturing costs (the cost of raw materials and sintering processes for solid electrolytes is 5-10 times that of liquid electrolytes) make it difficult to scale up for commercialization.

[0004] Patent CN113839096A uses fluoroethylene carbonate and lithium salt as synergistic plasticizers and initiators to achieve in-situ polymerization of polymer monomers at room temperature, improving battery safety. However, the liquid precursor content is >5% (accounting for more than 5% of the total battery mass), limiting the safety improvement; low-temperature performance is poor (capacity retention rate at -30℃ 0.2C discharge <60%). Patent CN116404146A uses a radial star-shaped nano-silicon-carbon composite material, preparing nano-silicon through metallothermic reduction and combining it with carbon nanomaterials, effectively mitigating volume expansion and improving battery capacity and rate performance. However, it suffers from short cycle life (capacity retention rate <70% after 1000 cycles at 0.5C) and poor safety (prone to thermal runaway in nail penetration tests). Patent CN117410501A forms a two-dimensional graphite-modified layer on the surface of aluminum foil using electrical discharge technology, and then coats it with a conductive coating containing conductive carbon black and carbon nanotubes. This significantly enhances the adhesion and conductivity between the current collector and the electrode, while also improving battery safety and rate performance. However, it cannot cope with internal short circuits under mechanical abuse (fails the nail penetration test) and does not improve wide-temperature performance. Patent CN120300273A enhances the thermal stability of the electrolyte and improves ionic conductivity and interface stability through a zirconium-based metal-organic framework (Zr-MOF). However, it has defects such as high interface impedance (>50Ω·cm²), poor wide-temperature performance (capacity retention rate <70% at -30℃), liquid content >5%, and insufficient safety.

[0005] Therefore, existing technologies are mostly limited to "single-dimensional" improvements and have failed to solve the problem of synergistic adaptation between various components. For example, simply reducing the liquid content will sacrifice interface and kinetic performance; only nano-sizing the electrodes will exacerbate interfacial side reactions; and simply adding a conductive coating to the current collector cannot cope with safe abuse. The lack of a systematic synergistic design among the "electrode-electrolyte-current collector" has made it impossible to break through the technical bottleneck and has always been difficult to simultaneously achieve the three core requirements of high safety, wide temperature range, and high energy density. Summary of the Invention

[0006] One of the objectives of this invention is to provide a method for preparing a solid-state-like lithium battery, which can produce a solid-state-like lithium battery with high safety, wide temperature range, and high energy density.

[0007] The second objective of this invention is to provide a type of solid-state lithium battery that features high safety, wide temperature range, and high energy density.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] On the one hand, a method for preparing a solid-state-like lithium battery is provided, which provides a positive electrode, a negative electrode, a separator and a precursor solution, assembles the positive electrode, the negative electrode and the separator into a cell, injects the precursor solution into the cell and carries out a polymerization reaction to form a solid-state-like electrolyte, thereby obtaining a solid-state-like lithium battery.

[0010] The preparation method of the positive electrode sheet is as follows: providing positive electrode raw materials: positive electrode active material, positive electrode conductive agent and positive electrode binder; mixing and dispersing the raw materials in a first solvent to obtain a positive electrode slurry; coating the positive electrode slurry onto the non-insulating surface of the positive electrode current collector to obtain the positive electrode sheet; wherein, the positive electrode current collector includes an aluminum foil and a solid electrolyte layer attached to one surface of the aluminum foil, the solid electrolyte layer being LLZTO or LATP; (after the solid electrolyte layer is attached to one surface of the aluminum foil, that surface is the insulating surface, and the opposite side is the non-insulating surface);

[0011] The method for preparing the negative electrode sheet is as follows: the negative electrode sheet active material, negative electrode conductive agent, and negative electrode binder are mixed and dispersed in a second solvent to obtain a negative electrode slurry; the negative electrode slurry is coated on a negative electrode current collector to obtain a negative electrode sheet.

[0012] The precursor solution contains polymerizable monomers, thermal initiators, and lithium salts; the precursor solution accounts for 1%-5% of the total mass of the solid-state lithium battery.

[0013] As a preferred method for preparing a solid-state lithium battery, the primary particle size D50 of the positive electrode active material is ≤200nm; and / or, the primary particle size D50 of the negative electrode active material is ≤200nm.

[0014] As a preferred method for preparing a solid-state lithium battery, the primary particle size D50 of the positive electrode active material is 50nm-100nm; and / or, the primary particle size D50 of the negative electrode active material is 100nm-200nm.

[0015] As a preferred method for preparing solid-state lithium batteries, the cathode material also includes nanoscale solid electrolyte particles.

[0016] As a preferred method for preparing solid-state lithium batteries, the particle size D50 of the nanoscale solid electrolyte particles is 90-110 nm; and / or, the amount of nanoscale solid electrolyte particles added is 5%-10% of the mass of the positive electrode active material; and / or, the nanoscale solid electrolyte particles are selected from LLZTO and / or LATP.

[0017] As a preferred method for preparing a solid-state lithium battery, the mass ratio of positive electrode active material, positive electrode conductive agent and positive electrode binder is (91-97):(1-3):(2-3).

[0018] As a preferred method for preparing a solid-state lithium battery, the positive electrode active material is selected from one or at least two of ternary materials, lithium iron phosphate, lithium-rich manganese-based materials, and lithium cobalt oxide; and / or, the positive electrode conductive agent is selected from acetylene black and / or Super P; and / or, the positive electrode binder is selected from PVDF.

[0019] As a preferred method for preparing solid-state-like lithium batteries, the ternary material is selected from LiNi. x Co y Mn 1-x-y O2, 0.6≤ x ≤ 0.9, 0.05 ≤ y ≤ 0.2, and x + y < 1.

[0020] As a preferred method for preparing a solid-state lithium battery, the active material of the negative electrode is selected from any one or at least two of nano-silicon-carbon, graphite, and hard carbon; and / or, the conductive agent of the negative electrode is selected from Super P; and / or, the binder of the negative electrode is selected from CMC and / or SBR.

[0021] As a preferred method for preparing solid-state-like lithium batteries, nano-silicon carbon is selected from SiO₂. X / C, 0.1≤x≤0.5.

[0022] As a preferred method for preparing solid-state lithium batteries, the mass ratio of negative electrode active material, negative electrode conductive agent, and negative electrode binder is (90-96):(1-3):(2-4).

[0023] As a preferred embodiment of the preparation method for solid-state lithium batteries, the polymerizable monomer is selected from any one or at least two of acrylate monomers, carbonate monomers, and methyl methacrylate; and / or, the thermal initiator is selected from azobisisobutyronitrile (AIBN); and / or, the lithium salt is selected from any one or at least two of LiFSI, LiPF6, lithium difluorooxalatoborate, lithium bis(trifluoromethanesulfonyl)imide, and lithium difluorodiooxalatophosphate.

[0024] As a preferred method for preparing solid-state lithium batteries, acrylate monomers are selected from any one or at least two of butyl acrylate, ethylene glycol methyl ether acrylate, PEGMA, TEGDA, and PTTEA; carbonate monomers are selected from any one or at least two of vinylene carbonate, ethylene ethylene carbonate, ethylene carbonate, propylene carbonate, and TMC.

[0025] As a preferred method for preparing solid-state-like lithium batteries, the amount of thermal initiator added is 2%-3% of the mass of the polymerizable monomer; and / or, the concentration of lithium salt is 1 mol / L-1.5 mol / L.

[0026] As a preferred method for preparing a solid-state lithium battery, the negative electrode current collector is a copper foil with a thickness of 4μm-10μm, or a copper foil with a carbon nanotube or graphene conductive framework on its surface (which can be made by coating, spraying, dipping or sputtering), or a composite copper foil composed of metal-polymer-metal.

[0027] As a preferred embodiment of the preparation method of solid-state lithium battery, the separator includes a PP base film and an Al2O3 ceramic layer with a thickness of 1μm-2μm coated on the surface of the PP base film. The thickness of the PP base film is 5μm-12μm; the thickness of the Al2O3 ceramic layer is 1μm-2μm, the porosity of the Al2O3 ceramic layer is 40%-50%, and the thermal pore-closing temperature of the Al2O3 ceramic layer is ≥130℃.

[0028] As a preferred method for preparing a solid-state-like lithium battery, the method for preparing the positive electrode includes the following steps:

[0029] (1) Positive electrode raw materials will be provided: positive electrode active material, positive electrode conductive agent and positive electrode binder;

[0030] (2) Add the cathode material to the first solvent and stir at a speed of 2000r / min-3000r / min for 4h-6h to obtain a cathode slurry with a solid content of 50%-60%;

[0031] (3) Coat the positive electrode slurry onto the non-insulating surface of the positive electrode current collector, with a coating density of 20 mg / cm³. 2 -28mg / cm 2 ;

[0032] (4) Dry at 100℃-120℃ to remove the first solvent;

[0033] (5) The positive electrode sheet is obtained by cold pressing and cutting.

[0034] As a preferred method for preparing solid-state lithium batteries, when the positive electrode active material is selected from ternary materials, the compaction density after cold pressing is 3.2 g / cm³-3.6 g / cm³; when the positive electrode active material is selected from lithium iron phosphate, the compaction density after cold pressing is 2.0 g / cm³-2.2 g / cm³; and when the positive electrode active material is selected from lithium cobalt oxide, the compaction density after cold pressing is 3.6 g / cm³-4.2 g / cm³.

[0035] As a preferred method for preparing a solid-state-like lithium battery, the method for preparing the negative electrode includes the following steps:

[0036] (1) Mix the negative electrode active material, negative electrode conductive agent and negative electrode binder into the second solvent, stir at a speed of 1500r / min-2500r / min for 3h-5h, and after uniform dispersion, a negative electrode slurry with a solid content of 50%-60% is obtained.

[0037] (2) Coat the negative electrode slurry onto the upper surface of the negative electrode current collector with a coating density of 10 mg / cm²-15 mg / cm².

[0038] (3) Bake in an oven, with the temperature gradually increasing from 80°C to 105°C;

[0039] (4) The negative electrode sheet is obtained by cold pressing and cutting.

[0040] As a preferred method for preparing solid-state lithium batteries, the compaction density of the negative electrode sheet is 1.5 g / cm³-1.8 g / cm³.

[0041] As a preferred method for preparing solid-state lithium batteries, when preparing the precursor solution, polymerizable monomers, thermal initiators and lithium salts are added sequentially in an inert atmosphere, and stirred for 2-4 hours until completely dissolved and clear.

[0042] As a preferred method for preparing a solid-state-like lithium battery, a positive electrode, a negative electrode, a separator, and a precursor solution are provided.

[0043] Stack or wind the positive electrode sheet, separator, and negative electrode sheet in sequence, then pack them into aluminum-plastic packaging bags and assemble them into battery cells; pre-vacuum them for 10-15 minutes at -0.09MPa to -0.1MPa.

[0044] At 5℃-25℃, inject the precursor solution and let it stand for more than 30 minutes to ensure that the positive electrode, negative electrode and separator are fully wetted.

[0045] Vacuum sealing is performed at 5℃-25℃ and -0.095MPa to -0.1MPa to remove air from the battery cell;

[0046] In a constant temperature oven at 50℃-65℃, the temperature is maintained for 1h-24h, preferably at 55℃-65℃ for 4h-8h, and more preferably at 60℃ for 6h, so that the thermal initiator initiates the polymerization of monomers to form a solid-like electrolyte layer, thereby obtaining a solid-like lithium battery.

[0047] Specifically, after obtaining the solid-state-like lithium battery, it is necessary to perform a formation process on the solid-state-like lithium battery. The formation process is a conventional technology in this field and will not be described in detail here.

[0048] On the other hand, a solid-state-like lithium battery prepared using the aforementioned method is provided.

[0049] The beneficial effects of this invention are:

[0050] The solid-state-like lithium battery of this invention adopts a three-in-one synergistic design of "nanosized electrode - ultra-low content in-situ polymerized electrolyte - safety modified current collector", which is achieved through the following specific technical features:

[0051] 1. Nanostructured electrode system: The primary particle size of the positive and negative electrode active materials is D50≤200nm. This nanostructure provides a huge wettable specific surface area and an extremely short ion solid-phase diffusion path for low-content electrolytes, which is the basis for solving the interfacial dynamics problem under ultra-low liquid content.

[0052] 2. Ultra-low content in-situ polymerized electrolyte system: formed by thermally initiated in-situ polymerization of a liquid precursor solution accounting for 1%-5% of the total battery mass. This system (such as PTTEA / PEGDA-AIBN-LiFSI / LiPF6) forms a unique structure of "rigid cross-linked network + flexible segments + a small amount of liquid channels" after polymerization. This structure is the core to achieve high intrinsic safety and good ion transport.

[0053] 3. Safety-Modified Current Collector System: The positive electrode current collector uses a composite current collector with a solid electrolyte layer (such as LLZTO or LATP) attached to its surface. This design acts as a physical insulation barrier in the event of diaphragm failure, and is a key guarantee for responding to mechanical abuse and achieving "active" safety protection;

[0054] The nano-electrode system, the ultra-low content in-situ polymerized electrolyte system, and the safety-modified current collector system are interdependent and synergistic: the nano-electrode ensures that the ultra-low content electrolyte can form a highly efficient ion transport interface; the safety current collector provides the final safety redundancy for the entire system; and the low-content, non-flammable electrolyte is the foundation of high safety. Together, they constitute an inseparable technological whole, resolving the contradictions that cannot be overcome by a single technological approach. Attached Figure Description

[0055] Figure 1 The image shows the DSC spectrum of the solid-like electrolyte in Example 1.

[0056] Figure 2 The image shows the FTIR spectrum of the solid-like electrolyte in Example 1.

[0057] Figure 3 The image shows the SEM spectrum of the solid-like electrolyte from Example 1. Detailed Implementation

[0058] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0059] Unless otherwise specified, all raw materials used in this invention are commercially available or can be prepared using conventional methods in this technical field.

[0060]

[0061] Example 1

[0062] 1. Preparation of the positive electrode:

[0063] Formulation: Nano-sized ternary materials (LiNi) 0.8 Co 0.1 Mn 0.1 O2, NCM811 (primary particle size D50≈200nm, specific surface area 20m² / g), conductive agent acetylene black, and binder polyvinylidene fluoride (PVDF) are mixed in a mass ratio of 96:2:2.

[0064] Process: The above mixture was added to an appropriate amount of N-methylpyrrolidone (NMP) solvent and stirred at 2000 rpm for 4 hours in a vacuum planetary mixer to form a uniform positive electrode slurry. The slurry was then uniformly coated onto a 12 μm thick aluminum foil (with a 2 μm thick Al2O3 ceramic layer on one side) using a coating machine, with a coating surface density of 25 mg / cm². The foil was then dried in an oven at 100℃-120℃ for 10 minutes, followed by cold pressing using a roller press to achieve a compaction density of 3.4 g / cm³, and finally cut into positive electrode sheets of the required size.

[0065] 2. Preparation of nano-sized negative electrode sheets:

[0066] Formulation: Nano-silicon-carbon composite material (nano-silicon-carbon composite material (SiO)) 0.3 The following ingredients are mixed in a mass ratio of 94:2:2:2:C: (primary particle size D50≈100nm), conductive agent Super P, binder sodium carboxymethyl cellulose (CMC), and styrene-butadiene rubber (SBR).

[0067] Process: The above mixture is added to deionized water and stirred to form a uniform negative electrode slurry. This slurry is then coated onto a 6μm thick copper foil with a coating density of 12mg / cm². The slurry is baked in an oven and heated in a gradient from 80℃ to 105℃ for 10 minutes, followed by cold pressing to obtain a negative electrode sheet with a compacted density of 1.6g / cm³.

[0068] 3. Preparation of liquid precursor solution:

[0069] In a glove box, pentaerythritol tetraacrylate (PTTEA) monomer was weighed, and then 2% (by mass) of its thermal initiator azobisisobutyronitrile (AIBN) was added. Lithium bisfluorosulfonyl imide (LiFSI) lithium salt was then added to prepare a solution with a lithium salt concentration of 1.2 mol / L. The solution was stirred thoroughly until completely dissolved and clear. This precursor solution accounts for approximately 3% of the mass of the subsequent battery.

[0070] 4. Cell assembly and in-situ polymerization:

[0071] The positive electrode, PP porous separator (2μm alumina ceramic layer + 5μm base film), and negative electrode are stacked in sequence and placed in an aluminum-plastic packaging bag. An appropriate amount of the above liquid precursor solution is injected using a precision syringe to ensure that the separator and electrode are fully wetted. The wetting rate test method is: "The wetting rate is tested by weighing method (test steps: mass of unwetted electrode m1, mass of excess solution on the surface after wetting m2, wetting rate = (m2-m1) / electrode pore volume × precursor solution density × 100%), the wetting rate of the nanoelectrode to the precursor solution is ≥95%".

[0072] Vacuum sealing was performed at 60°C to remove air from the cell. The cell was then placed in a constant temperature oven at 60°C and left to stand for 12 hours, allowing AIBN to decompose and generate free radicals, which triggered the complete cross-linking polymerization of PTTEA monomers to form a solid-state electrolyte, thus producing a solid-state lithium battery. After formation, a pouch-type solid-state lithium battery was finally obtained.

[0073] Example 2

[0074] 1. Preparation of nano-sized positive electrode sheets:

[0075] Formulation and process: The basic steps are the same as in Example 1, but garnet-type solid electrolyte (Li) accounting for 5% of the mass of the positive electrode active material is additionally added to the positive electrode slurry.6.4 La3Zr 1.4 Ta 0.6 O 12 LLZTO nanoparticles. The ratio of other components was adjusted to: nano-sized NCM811: acetylene black: PVDF = 91:2:2 (LLZTO was added separately).

[0076] 2. Preparation of nano-sized negative electrode sheet: exactly the same as in Example 1.

[0077] 3. Preparation of liquid precursor solution:

[0078] Polyethylene glycol diacrylate (PEGDA, Mn=700) was used as the polymerization monomer. The thermal initiator AIBN was added at 3% of the PEGDA monomer mass. Lithium hexafluorophosphate (LiPF6) was used as the lithium salt, prepared as a 1.2 mol / L solution. The precursor solution accounted for approximately 2% of the battery mass.

[0079] 4. Cell assembly and in-situ polymerization:

[0080] The assembly process was the same as in Example 1. The polymerization reaction conditions were adjusted to be heated at 65°C for 8 hours.

[0081] Example 3:

[0082] 1. Preparation of nano-sized positive electrode sheets:

[0083] A. Current collector pretreatment: Aluminum foil with a total thickness of about 17μm and a mixed ceramic layer (Al2O3-SiO2 composite material with a mass ratio of 7:3) coated on one side of the surface is used as the positive electrode current collector.

[0084] B. Slurry and Coating: The positive electrode slurry formulation is the same as in Example 2 (i.e., containing 5% LLZTO particles). The slurry is coated onto the smooth surface of the current collector without the ceramic layer, dried, cold-pressed, and then ready for use.

[0085] 2. Preparation of nano-sized negative electrode sheet: exactly the same as in Example 1.

[0086] 3. Preparation of liquid precursor solution: Same as in Example 1 (i.e., PTTEA + 2% AIBN + 1.0 mol / L).

[0087] 4. Cell assembly and in-situ polymerization: The process is the same as in Example 1.

[0088] Comparative Example 1

[0089] This comparative example is basically the same as Example 1, except that:

[0090] Positive electrode: The active material uses conventional micron-sized LiNi. 0.8Co 0.1 Mn 0.1 O2 (NCM811), median primary particle size D50≈1.5μm.

[0091] Negative electrode: The active material uses conventional micron-sized artificial graphite, with a median particle size D50 of approximately 1.2 μm.

[0092] Electrolyte: The formulation and process of Example 1 were used exactly. The same mass percentage (3%) of liquid precursor solution (PTTEA + 2% AIBN + 1.0 mol / L) was injected, and in-situ polymerization was carried out under the same conditions (60°C, 12 h).

[0093] Comparative Example 2

[0094] This comparative example is basically the same as Example 1, except that:

[0095] Positive current collector: Ordinary light aluminum foil (without any ceramic coating or solid electrolyte composite layer) is used, and all other steps and materials are exactly the same as in Example 1.

[0096] Comparative Example 3

[0097] This comparative example is basically the same as Example 3, except that the electrolyte is not produced by in-situ polymerization, but is directly injected with a traditional liquid electrolyte (such as 1.2 mol / L LiPF6 in EC / DEC / EMC) accounting for about 12.5% ​​of the total mass of the battery.

[0098] like Figure 1 As shown, the glass transition temperature (Tg) of the solid-like electrolyte in Example 1 was measured by differential scanning calorimetry (DSC) to be in the range of -20°C to -10°C, proving the presence of flexible segments.

[0099] like Figure 2 As shown, the acrylate double bond (located at 1630 cm⁻¹) in the solid-like electrolyte of Example 1 was detected by Fourier transform infrared spectroscopy (FTIR). -1 and 810 cm -1 The disappearance of nearby characteristic peaks proves that the polymerization reaction is complete and a cross-linked network has been formed.

[0100] like Figure 3 As shown, the cross-sectional morphology of the solid-like electrolyte in the embodiment was observed by scanning electron microscopy (SEM), and ion transport channels were found distributed in the continuous phase.

[0101] The performance of the batteries prepared in Examples 1-3 and Comparative Examples 1-3 was tested, and the results are shown in Table 1.

[0102] Table 1. Battery performance test results

[0103]

[0104] Comparative Example 1 (micron electrode) demonstrates that without the synergy of nano-electrodes, the ultra-low electrolyte content system leads to severe degradation in low-temperature performance (<45%) and interfacial impedance (>150 Ω·cm²). Comparative Example 2 (conventional current collector) demonstrates that without the synergy of a safety current collector, even with nanoelectrodes and a low electrolyte content, the battery still fails the nail penetration test. Comparative Example 3 (traditional electrolyte) demonstrates that without the synergy of an ultra-low polymeric electrolyte, even with nanoelectrodes and a safety current collector, the battery's energy density (290 Wh / kg) and safety (failure to pass the nail penetration test) both fail to meet standards. Therefore, it is evident that the three technical features described in this invention are not simply superimposed, but rather produce a close and inseparable synergistic effect. The absence of any one of them will prevent the entire technical solution from achieving the expected high safety, high energy density, and wide temperature range performance, which fully demonstrates the non-obviousness of this invention.

[0105] The comparison shows that this invention successfully solves the industry problem of "the incompatibility between high safety and high energy density / wide temperature range performance" through the synergistic innovation of "nanosized electrode - ultra-low content in-situ polymeric electrolyte - safe insulating current collector".

[0106] This invention is not a simple superposition of existing technologies. Its core lies in revealing the profound interdependence among nano-electrodes, ultra-low content in-situ polymerized electrolytes, and safe insulating current collectors. Based on this, a brand-new and efficient technical system is constructed, thereby producing a synergistic effect of "1+1+1>3".

[0107] The above embodiments are only used to illustrate the detailed method of the present invention. The present invention is not limited to the above detailed method, that is, it does not mean that the present invention must rely on the above detailed method to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a solid-state-like lithium battery, characterized in that, A positive electrode, a negative electrode, a separator, and a precursor solution are provided. The positive electrode, a negative electrode, and a separator are assembled into a cell. The precursor solution is injected into the cell and a polymerization reaction is carried out to form a solid-like electrolyte, thus producing a solid-like lithium battery. The preparation method of the positive electrode sheet is as follows: providing positive electrode raw materials: positive electrode active material, positive electrode conductive agent and positive electrode binder; mixing and dispersing the raw materials in a first solvent to obtain a positive electrode slurry; coating the positive electrode slurry onto the non-insulating surface of the positive electrode current collector to obtain a positive electrode sheet; wherein, the positive electrode current collector includes an aluminum foil and a solid electrolyte layer attached to one surface of the aluminum foil, the solid electrolyte layer being LLZTO or LATP; The method for preparing the negative electrode sheet is as follows: the negative electrode sheet active material, negative electrode conductive agent, and negative electrode binder are mixed and dispersed in a second solvent to obtain a negative electrode slurry; the negative electrode slurry is coated on a negative electrode current collector to obtain a negative electrode sheet. The precursor solution contains polymerizable monomers, thermal initiators, and lithium salts; the precursor solution accounts for 1%-5% of the total mass of the solid-state lithium battery.

2. The method for preparing a solid-state-like lithium battery according to claim 1, characterized in that, The primary particle size D50 of the positive electrode active material is ≤200nm; and / or, the primary particle size D50 of the negative electrode active material is ≤200nm.

3. The method for preparing a solid-state-like lithium battery according to claim 1, characterized in that, The primary particle size D50 of the positive electrode active material is 50nm-100nm; and / or, the primary particle size D50 of the negative electrode active material is 100nm-200nm.

4. The method for preparing a solid-state-like lithium battery according to claim 1, characterized in that, The cathode material also includes nanoscale solid electrolyte particles.

5. The method for preparing a solid-state-like lithium battery according to claim 4, characterized in that, The particle size D50 of the nanoscale solid electrolyte particles is 90nm-110nm; and / or, the amount of nanoscale solid electrolyte particles added is 5%-10% of the mass of the positive electrode active material; and / or, the nanoscale solid electrolyte particles are selected from LLZTO and / or LATP.

6. The method for preparing a solid-state-like lithium battery according to claim 1, characterized in that, The mass ratio of the positive electrode active material, the positive electrode conductive agent and the positive electrode binder is (91-97):(1-3):(2-3).

7. The method for preparing a solid-state-like lithium battery according to claim 1, characterized in that, The positive electrode active material is selected from one or at least two of ternary materials, lithium iron phosphate, lithium-rich manganese-based materials, and lithium cobalt oxide; and / or, the positive electrode conductive agent is selected from acetylene black and / or Super P; and / or, the positive electrode binder is selected from PVDF.

8. The method for preparing a solid-state-like lithium battery according to claim 7, characterized in that, The ternary material is selected from LiNi x Co y Mn 1-x-y O2, 0.6 ≤ x ≤ 0.9, 0.05 ≤ y ≤ 0.2, and x + y < 1.

9. The method for preparing a solid-state-like lithium battery according to claim 1, characterized in that, The negative electrode active material is selected from any one or at least two of nano-silicon carbon, graphite, and hard carbon; and / or, the negative electrode conductive agent is selected from Super P; and / or, the negative electrode binder is selected from CMC and / or SBR.

10. The method for preparing a solid-state-like lithium battery according to claim 9, characterized in that, Nano-silicon carbon is selected from SiO x / C, 0.1≤x≤0.

5.

11. The method for preparing a solid-state-like lithium battery according to claim 1, characterized in that, The mass ratio of the negative electrode active material, negative electrode conductive agent, and negative electrode binder is (90-96):(1-3):(2-4).

12. The method for preparing a solid-state-like lithium battery according to claim 1, characterized in that, The polymerizable monomer is selected from any one or at least two of acrylate monomers, carbonate monomers, and methyl methacrylate; and / or, the thermal initiator is selected from azobisisobutyronitrile (AIBN); and / or, the lithium salt is selected from any one or at least two of LiFSI, LiPF6, lithium difluorooxalate borate, lithium bis(trifluoromethanesulfonyl)imide, and lithium difluorodioxalate phosphate.

13. The method for preparing a solid-state-like lithium battery according to claim 12, characterized in that, The acrylate monomers are selected from any one or at least two of butyl acrylate, ethylene glycol methyl ether acrylate, PEGMA, TEGDA, and PTTEA; the carbonate monomers are selected from any one or at least two of vinylene carbonate, ethylene ethylene carbonate, ethylene carbonate, and TMC.

14. The method for preparing a solid-state-like lithium battery according to claim 1, characterized in that, The amount of thermal initiator added is 2%-3% of the mass of the polymerizable monomer; and / or, the concentration of lithium salt is 1 mol / L-1.5 mol / L.

15. The method for preparing a solid-state-like lithium battery according to any one of claims 1 to 14, characterized in that, The negative electrode current collector is a copper foil with a thickness of 4μm-10μm, or a copper foil with a multilayer or mesh conductive framework of carbon nanotubes or graphene on its surface, or a composite copper foil composed of metal-polymer-metal.

16. The method for preparing a solid-state-like lithium battery according to any one of claims 1 to 14, characterized in that, The diaphragm includes a PP base membrane and an Al2O3 ceramic layer with a thickness of 1μm-2μm coated on the surface of the PP base membrane. The thickness of the PP base membrane is 5μm-12μm. The thickness of the Al2O3 ceramic layer is 1μm-2μm, the porosity of the Al2O3 ceramic layer is 40%-50%, and the thermal closure temperature of the Al2O3 ceramic layer is ≥130℃.

17. The method for preparing a solid-state-like lithium battery according to any one of claims 1 to 14, characterized in that, The preparation method of the positive electrode includes the following steps: (1) Positive electrode raw materials will be provided: positive electrode active material, positive electrode conductive agent and positive electrode binder; (2) Add the cathode material to the first solvent and stir at a speed of 2000r / min-3000r / min for 4h-6h to obtain a cathode slurry with a solid content of 50%-60%; (3) Coat the positive electrode slurry onto the non-insulating surface of the positive electrode current collector, with a coating density of 20 mg / cm³. 2 -28mg / cm 2 ; (4) Dry at 100℃-120℃ to remove the first solvent; (5) The positive electrode sheet is obtained by cold pressing and cutting.

18. The method for preparing a solid-state-like lithium battery according to claim 17, characterized in that, When the positive electrode active material is selected from ternary materials, the compaction density after cold pressing is 3.2 g / cm³-3.6 g / cm³; when the positive electrode active material is selected from lithium iron phosphate, the compaction density after cold pressing is 2.0 g / cm³-2.2 g / cm³; and when the positive electrode active material is selected from lithium cobalt oxide, the compaction density after cold pressing is 3.6 g / cm³-4.2 g / cm³.

19. The method for preparing a solid-state-like lithium battery according to any one of claims 1 to 14, characterized in that, The preparation method of the negative electrode includes the following steps: (1) Mix the negative electrode active material, negative electrode conductive agent and negative electrode binder into the second solvent, stir at a speed of 1500r / min-2500r / min for 3h-5h, and after uniform dispersion, a negative electrode slurry with a solid content of 50%-60% is obtained. (2) Coat the negative electrode slurry onto the upper surface of the negative electrode current collector with a coating density of 10 mg / cm²-15 mg / cm². (3) Bake in an oven, with the temperature gradually increasing from 80°C to 105°C; (4) The negative electrode sheet is obtained by cold pressing and cutting.

20. The method for preparing a solid-state-like lithium battery according to claim 19, characterized in that, The compaction density of the negative electrode sheet is 1.5 g / cm³-1.8 g / cm³.

21. The method for preparing a solid-state-like lithium battery according to any one of claims 1 to 14, characterized in that, When preparing the precursor solution, add the polymerizable monomer, thermal initiator and lithium salt sequentially in an inert atmosphere, and stir for 2-4 hours until completely dissolved and clear.

22. The method for preparing a solid-state-like lithium battery according to any one of claims 1 to 14, characterized in that, We provide positive electrode plates, negative electrode plates, separators, and precursor solutions; Stack or wind the positive electrode sheet, separator, and negative electrode sheet in sequence, then pack them into aluminum-plastic packaging bags and assemble them into battery cells; pre-evacuate the battery at -0.09MPa to -0.1MPa for 10-15 minutes. At 5℃-25℃, inject the precursor solution and let it stand for more than 30 minutes to ensure that the positive electrode, negative electrode and separator are fully wetted. Vacuum sealing is performed at 5℃-25℃ and -0.095MPa to -0.1MPa to remove air from the battery cell; In a constant temperature oven at 50℃-65℃, the temperature is maintained for 1h-24h, preferably at 55℃-65℃ for 4h-8h, and more preferably at 60℃ for 6h, so that the thermal initiator initiates the polymerization of monomers to form a solid-like electrolyte layer, thereby obtaining a solid-like lithium battery.

23. A solid-state-like lithium battery prepared by the preparation method according to any one of claims 1 to 22.

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