Solid-state battery and preparation method and application thereof

Abstract

The invention provides a solid-state battery and a preparation method and application thereof, and relates to the technical field of solid-state batteries. Specifically, an oxide solid electrolyte is pressed to obtain a porous green body; preparing a dispersion liquid of a polymer precursor containing a thermal polymerization monomer, a lithium salt and an initiator; infiltrating the porous green body in the dispersion liquid in a vacuum environment, then transferring the porous green body to a non-vacuum environment, and separating to obtain an electrolyte precursor; and assembling the electrolyte precursor and an electrode to obtain a battery precursor, and performing constant-temperature treatment to obtain the solid-state battery. The electrolyte obtained by the preparation method has high bulk phase ionic conductivity, extremely low interface impedance and high mechanical strength, the process is simple, the cost is low, electrolyte synthesis and battery assembly are completed in one step through an in-situ polymerization strategy in the battery, and a new path is opened up for large-scale manufacturing of all-solid-state batteries.

Description

Technical Field

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

[0002] All-solid-state lithium batteries are considered an ideal choice for next-generation energy storage devices due to their high energy density and high safety. However, traditional all-solid-state batteries still face problems such as poor interfacial contact between the solid electrolyte and electrode materials, high interfacial impedance, and slow lithium-ion transport kinetics, which severely limit the battery's rate performance and cycle life. The commercialization process of all-solid-state batteries is constrained by the following key issues: (1) The solid-solid interface impedance is huge: Traditional inorganic solid electrolytes (such as oxide LLZO) are rigid and have point-to-point contact with the electrode active particles, resulting in a small effective contact area and extremely high interfacial ion transport impedance. This is the primary reason for the high internal resistance, poor rate performance and rapid capacity decay of the battery.

[0003] (2) The inherent contradiction between bulk ionic conductivity and interfacial contact: Although dense inorganic electrolytes have high bulk ionic conductivity and mechanical strength, their rigid surfaces cannot be adapted to electrodes, resulting in prominent interfacial problems; soft polymer electrolytes have good interfacial contact, but their bulk ionic conductivity, especially at room temperature, is low, and their mechanical strength is insufficient, making it difficult to effectively suppress the growth of lithium dendrites; at the same time, the traditional homogeneous composite electrolytes obtained by physical blending are made by mixing inorganic fillers with polymers. Although this can improve the interface to a certain extent, the random distribution of inorganic fillers will destroy the continuity of the polymer phase, often leading to a significant decrease in bulk ionic conductivity. Moreover, the fillers are prone to agglomeration, generating interfacial defects and forming dead volumes. Therefore, it is difficult to achieve a synergistic improvement in bulk ionic conductivity and interfacial contact performance.

[0004] (3) The preparation process is complex and difficult to scale up: The composite solid electrolyte with an ideal three-dimensional interpenetrating network structure can effectively suppress the core defects in ion transport, interface stability, mechanical properties and energy density, but it usually requires complex template method, high temperature sintering or precise photolithography technology, which is costly and has poor compatibility with existing battery manufacturing processes.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The primary objective of this invention is to provide a method for preparing a solid-state battery that simultaneously achieves high bulk ionic conductivity, excellent interfacial contact, high mechanical strength electrolyte structure, and a simple preparation method.

[0007] A second objective of this invention is to provide a solid-state battery.

[0008] A third objective of this invention is to provide the application of the aforementioned solid-state battery preparation method in the field of solid-state batteries.

[0009] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: A method for preparing a solid-state battery includes the following steps: Porous green bodies were obtained by pressing with oxide solid electrolytes; Prepare a dispersion of a polymer precursor containing a thermally polymerizable monomer, a lithium salt, and an initiator; In a vacuum environment, the porous green body is immersed in the dispersion and then transferred to a non-vacuum environment to separate and obtain the electrolyte precursor. The electrolyte precursor and electrodes are assembled to obtain a battery precursor, which is then subjected to isothermal treatment to obtain a solid-state battery.

[0010] Preferably, the porosity of the porous green body is 10% to 40%.

[0011] Preferably, the pressing pressure is 100MPa~400MPa.

[0012] Preferably, the thermally polymerizable monomer includes at least one of acrylate monomers, vinyl monomers, and epoxy monomers.

[0013] Preferably, the oxide solid electrolyte includes at least one of garnet-type solid electrolyte, NASICON-type solid electrolyte, and perovskite-type solid electrolyte.

[0014] Preferably, the lithium salt comprises at least one of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium fluorosulfonyl(trifluoromethanesulfonyl)imide, lithium bis(oxalato)borate, lithium difluorooxalato)borate, and lithium hexafluorophosphate.

[0015] More preferably, the acrylate monomers include at least one of polyethylene glycol methyl ether acrylate, polyethylene glycol diacrylate, trimethylolpropane triacrylate, methoxy polyethylene glycol methacrylate, acrylonitrile, and pentaerythritol tetraacrylate.

[0016] More preferably, the vinyl monomers include at least one of ethylene carbonate, vinylene carbonate, allyl methyl carbonate, ethyl propylene carbonate, diallyl carbonate, diallyl pyrocarbonate, bis(2-methylallyl) carbonate, cyanoethyl acrylate, N-vinylpyrrolidone, 1,3-butanediol divinyl ether, and vinylene carbonate.

[0017] More preferably, the epoxy monomer includes at least one of ethylene oxide, propylene oxide, epichlorohydrin, ethylene glycol diglycidyl ether, allyl glycidyl ether, 1,4-butanediol diglycidyl ether, glycerol propoxy triglycidyl ether, and vinylcyclohexene dioxide.

[0018] Preferably, the temperature of the constant temperature treatment is 50℃~70℃, and the time of the constant temperature treatment is 6h~12h.

[0019] Preferably, the molar ratio of the initiator to the thermally polymerizable monomer is 0.1% to 5.0%.

[0020] Preferably, the concentration of the lithium salt in the dispersion is 1 mol / L to 5 mol / L.

[0021] Preferably, the vacuum level of the vacuum environment is ≤1 kPa, and / or the pressure of the non-vacuum environment is ≥101.325 kPa.

[0022] A solid-state battery is prepared using the solid-state battery preparation method described above.

[0023] Preferably, the solid-state battery includes electrodes and a solid electrolyte disposed between the electrodes; The solid electrolyte includes a porous framework and a cross-linked polymer supported on the porous framework; The concentration of the crosslinked polymer increases in the direction from the porous framework to the electrode surface.

[0024] The application of the solid-state battery preparation method described herein in the field of solid-state batteries.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention achieves synergistic optimization of performance, including: firstly, high bulk ionic conductivity, which, according to the test, can reach 10. -4 The S / cm level is comparable to that of pure oxide tablets, and far exceeds that of traditional composite electrolytes that are simply blended with the same components; secondly, it has extremely low interfacial resistance: the interfacial resistance with lithium metal can be reduced to 100 Ω·cm. 2 Below, compared to pure oxide tablets (typically >1000 Ω·cm) 2 The first is that the modulus of the electrolyte is reduced by an order of magnitude; the second is that it has high mechanical strength: the Young's modulus of the electrolyte exceeds 5 GPa through nanoindentation testing, which shows that it has excellent anti-dendritic ability.

[0026] (2) The process of the present invention is simple, low in cost, and has broad prospects for industrialization. Specifically, the preparation method of the present invention avoids high-temperature sintering, has a simple process and low energy consumption; the electrolyte synthesis and battery assembly are completed in one step through the in-situ polymerization strategy inside the battery, and the heat of the polymerization process causes the polymer to flow slightly, which can automatically repair the tiny interfacial gaps and achieve a high yield; the process of the present invention has good compatibility with existing battery production processes (coating, stacking or winding, etc.), opening up a new path for the large-scale manufacturing of all-solid-state batteries. Detailed Implementation

[0027] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0028] A key technical challenge for all-solid-state batteries is achieving a balance between high bulk ionic conductivity, excellent interfacial contact, high mechanical strength electrolyte structure, and a simple fabrication method. To overcome these shortcomings, this invention provides a novel electrolyte solution for all-solid-state batteries. The technical solution of this invention achieves the following four typical effects: First, this invention synergistically resolves the contradiction between bulk transport and interfacial contact. Instead of simply compromising performance through material mixing, it achieves an organic combination of "internal rigid high-speed channels" and "flexible close contact on both sides" within the same electrolyte structure through structural design.

[0029] Second, the present invention significantly reduces the interface impedance of solid-state batteries by using a flexible interface layer to achieve a change from point contact to surface contact between the electrolyte and the electrode, thereby significantly improving ion transport efficiency.

[0030] Third, this invention improves the overall mechanical strength and anti-dendritic ability of the electrolyte, ensuring that there is a continuous rigid skeleton inside the battery to physically prevent lithium dendrites from penetrating.

[0031] Fourth, this invention provides a simple, efficient, and compatible preparation method that avoids high-temperature sintering and complex processes, enabling low-cost, large-scale preparation of functional gradient structures.

[0032] The first aspect of the present invention is to provide a method for preparing a solid-state battery, which mainly includes the following steps S1 to S4; the core of the preparation process of the present invention is: by combining "vacuum impregnation" and "in-situ thermal polymerization in the battery", a composite electrolyte with a functional gradient structure is prepared in one step, and the battery is encapsulated at the same time.

[0033] S1. A porous green body is obtained by pressing with an oxide solid electrolyte; S2. Prepare a dispersion of a polymer precursor containing a thermally polymerizable monomer, a lithium salt, and an initiator; S3. Under vacuum conditions, the porous green body is immersed in the dispersion liquid and then transferred to a non-vacuum environment to separate and obtain the electrolyte precursor. S4. Assemble the electrolyte precursor and the electrode to obtain the battery precursor, and obtain the solid-state battery after isothermal treatment.

[0034] In a preferred embodiment, the oxide solid electrolyte includes at least one of garnet-type solid electrolyte, NASICON-type solid electrolyte, and perovskite-type solid electrolyte; in some embodiments, the garnet-type solid electrolyte includes, but is not limited to, LLZO (Li7La3Zr2O). 12 ), LLZNO (Li 6.75 La3Zr 1.75 Nb 0.25 O 12 ), LLZTO (Li 6.4 La3Zr 1.4 Ta 0.6 O 12 The NASICON-type solid electrolyte includes, but is not limited to, LATP (Li 1+x Al x Ti 2-x (PO4)3), LAGP (Li 1+x Al x Ge 2-x (PO4)3), the perovskite-type solid electrolyte includes, but is not limited to, LLTO (Li 3x La 2 / 3-x TiO3). In some preferred embodiments, the oxide solid electrolyte is a garnet-type solid electrolyte, preferably LLZO and its doped variants, which have the best chemical and electrochemical stability to lithium metal and are ideal for constructing high-energy-density lithium metal batteries.

[0035] In a preferred embodiment, the pressing pressure is 100MPa to 400MPa, including but not limited to any one or any two of 100, 125, 150, 175, 200, 225, 250, 275, 300, 325, 350, 375, and 400 (MPa); in some more preferred embodiments, the pressing time and pressure are adaptively adjusted in a coordinated manner to obtain an electrolyte green compact with a specific porosity.

[0036] In a preferred embodiment, the porosity of the porous green body is 10% to 40%, including but not limited to any one or any two of the following values: 10%, 12%, 15%, 18%, 20%, 24%, 25%, 28%, 30%, 32%, 35%, 38%, and 40%; the electrolyte green body with the above-mentioned specific porosity serves as the rigid framework and ion conduction channel for subsequent composites.

[0037] In one preferred embodiment, the thermally polymerizable monomer includes at least one of acrylate monomers, vinyl monomers, and epoxy monomers; it is understood that several monomers with different functionalities can also be mixed. The present invention can precisely design and control the crosslinking density and chain segment mobility of the polymer network in the finished solid-state battery, thereby balancing mechanical strength and ionic conductivity.

[0038] In some embodiments, the acrylate monomers include at least one selected from polyethylene glycol methyl ether acrylate (CAS: 26570-48-9), polyethylene glycol diacrylate (CAS: 32171-39-4), trimethylolpropane triacrylate (CAS: 3290-92-4), methoxy polyethylene glycol methacrylate (CAS: 26915-72-0), acrylonitrile (CAS: 107-13-1), and pentaerythritol tetraacrylate (CAS: 4986-89-4).

[0039] In some embodiments, the vinyl monomers include at least one of ethylene carbonate, vinylene carbonate, allyl methyl carbonate, ethyl propylene carbonate, diallyl carbonate, diallyl pyrocarbonate, bis(2-methylallyl) carbonate, cyanoethyl acrylate, N-vinylpyrrolidone, 1,3-butanediol divinyl ether, and vinylene carbonate.

[0040] In some embodiments, the epoxy monomers include at least one of ethylene oxide, propylene oxide, epichlorohydrin, ethylene glycol diglycidyl ether, allyl glycidyl ether, 1,4-butanediol diglycidyl ether, glycerol propoxy triglycidyl ether, and vinylcyclohexene dioxide.

[0041] In a preferred embodiment, the lithium salt comprises at least one of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium fluorosulfonyl(trifluoromethanesulfonyl)imide (LiFTFSI), lithium bis(oxalato)borate (LiBOB), lithium difluorooxalato)borate (LiDFOB), and lithium hexafluorophosphate (LiPF6). In some optional embodiments, the dispersion further comprises a lithium-replenishing additive or a lithium-containing functional additive, the specific type of which can be conventional or unconventional, to simultaneously optimize bulk conductivity and interfacial stability.

[0042] In one preferred embodiment, the initiator includes, but is not limited to, azobisisobutyronitrile (AIBN), benzoyl peroxide (BPO), dicumyl peroxide (DCP), etc.; in some embodiments, if increasing production speed is desired, the dispersion also includes a photoinitiator.

[0043] In a preferred embodiment, the solvent of the dispersion includes at least one of acetonitrile, tetrahydrofuran, N-methylpyrrolidone, and sulfolane. It should be noted that in this invention, a low-boiling-point, low-viscosity solvent is preferred to ensure that the precursor dispersion has good permeability and can be completely removed in the subsequent vacuum environment and heating polymerization process, ultimately obtaining a truly solvent-free all-solid electrolyte.

[0044] In a preferred embodiment, the molar ratio of the initiator to the thermally polymerizable monomer is 0.1% to 5.0%, or the mass ratio of the initiator to the thermally polymerizable monomer is 0.1% to 3.0%.

[0045] In a preferred embodiment, the molar ratio of the thermally polymerized monomer to the lithium element in the lithium salt is ≤20.

[0046] In a preferred embodiment, the concentration of the lithium salt in the dispersion is 1 mol / L to 5 mol / L.

[0047] In a preferred embodiment, the vacuum level of the vacuum environment is ≤1 kPa (i.e., ≤10 mbar or ≤7.5 Torr); the non-vacuum environment can be at atmospheric pressure or high pressure, and the pressure of the non-vacuum environment is ≥101.325 kPa.

[0048] In a preferred embodiment, the porous green body is impregnated in a vacuum environment for 30 minutes to 2 hours. After being transferred to a non-vacuum environment, it is left to stand for 1 hour to 6 hours, and then the impregnated green body is separated to obtain the electrolyte. It is understood that in this invention, the green body and dispersion are first transferred as a whole to a vacuum environment, the air in the pores of the green body is expelled by vacuuming, and then the pressure is restored to a certain level, using the pressure difference to allow the dispersion to fully and deeply penetrate into the pore network of the inorganic green body.

[0049] In a preferred embodiment, the assembly is carried out in an inert atmosphere, which includes, but is not limited to, nitrogen, helium, neon, argon, etc.

[0050] In a preferred embodiment, the isothermal treatment temperature is 50℃~70℃, and the isothermal treatment time is 6h~12h. In some optional embodiments, the isothermal treatment temperature includes, but is not limited to, any one or any two of the following: 50, 52, 55, 58, 60, 62, 65, 68, 70 (℃).

[0051] It is worth noting that the above-mentioned constant temperature treatment conditions need to be maintained in this invention, on the one hand to allow the solvent to evaporate, and on the other hand to decompose the thermal initiator, initiating in-situ cross-linking polymerization of monomers inside the pores of the precursor and at the interface between the electrolyte and the electrodes on both sides, forming a stable polymer network.

[0052] In a preferred embodiment, after assembling the battery precursor, an external pressure is applied to the battery precursor, followed by the isothermal treatment; the pressure range of the external pressure is 100MPa~200MPa.

[0053] A second aspect of the present invention is to provide a solid-state battery product obtained by the preparation method described in the first aspect.

[0054] In a preferred embodiment, the solid-state battery includes electrodes and a solid electrolyte disposed between the electrodes; the solid electrolyte includes a porous framework and a cross-linked polymer loaded on the porous framework; wherein, the concentration of the cross-linked polymer increases in the direction from the interior of the porous framework to the electrode surface. It is understood that the cross-linked polymer can be loaded in the pores of the porous framework or on its surface; the term "increasing trend" means that the concentration exhibits a gradient increase, a continuous increase, or both.

[0055] The concentration-increasing electrolyte structure formed in this invention can be understood as follows: (1) Core layer: mainly composed of oxide particles in contact with each other, forming a continuous phase with high ionic conductivity and high mechanical modulus, responsible for rapid bulk ion transport and dendrite blocking.

[0056] (2) Transition zone / interface layer: On the outside of the core layer, the content of polymer phase gradually increases, forming a gradient region with continuous changes in composition and properties; this region is composed of an "oxide skeleton" and a "polymer network running through it", achieving a balance between rigidity and flexibility.

[0057] (3) Surface layer: In the outermost layer, the polymer phase becomes dominant, forming a soft, dense, and large-area surface contact with the positive and negative electrodes, thereby minimizing the interfacial impedance.

[0058] A third aspect of the present invention is to provide the application of the preparation method as described in the first aspect in the field of solid-state batteries.

[0059] Example 1 (1) Preparation of porous inorganic green sheets: LLZTO (Li) oxide solid electrolyte powder was used to prepare the green sheets. 6.4 La3Zr 1.4 Ta 0.6 O 12 The green sheet was pressed at 200 MPa to obtain a dense green sheet with a porosity of 20%.

[0060] (2) Preparation of polymer precursor solution: dissolve polyethylene glycol diacrylate (PEGDA, Mn=250), lithium bis(trifluoromethanesulfonyl)imide, and azobisisobutyronitrile in acetonitrile to form a homogeneous solution; the molar ratio of polyethylene glycol diacrylate, lithium bis(trifluoromethanesulfonyl)imide, and azobisisobutyronitrile is 100:8:3, and the concentration of bis(trifluoromethanesulfonyl)imide in the solution is 3 mol / L.

[0061] (3) Vacuum-assisted impregnation: The inorganic green sheet prepared in step (1) is placed in the polymer precursor solution in step (2) and transferred as a whole to a vacuum environment; then the atmospheric pressure (1 atmosphere) is restored, and the pressure difference is used to allow the precursor solution to fully and deeply penetrate into the pore network of the inorganic sheet.

[0062] (4) Battery assembly and in-situ polymerization: The fully impregnated composite green sheet is used as the electrolyte, and the positive electrode NMC811 (area loading of 3.0 mAh / cm²) is used. 2 The lithium foil metal anode is rapidly assembled into a coin cell in an inert atmosphere glove box, and a stacking pressure of 100 MPa is applied.

[0063] (5) The assembled battery is placed in a constant temperature environment of 60°C and kept warm for 6 hours to obtain the solid-state battery of this embodiment.

[0064] Example 2: Basically the same as Example 1, except that the type of oxide solid electrolyte powder in step (1) is replaced with LLZO (Li7La3Zr2O). 12 The porosity is 30%.

[0065] Example 3: It is basically the same as Example 1, except that the porosity is 40% in step (1).

[0066] Example 4: It is basically the same as Example 1, except that the porosity is 10% in step (1).

[0067] Example 5: It is basically the same as Example 1, except that in step (2), polyethylene glycol diacrylate is replaced with another monomer, ethylene carbonate.

[0068] Example 6: It is basically the same as Example 1, except that in step (2), polyethylene glycol diacrylate is replaced with another monomer, ethylene oxide.

[0069] Comparative Example 1: Only step (1) of Example 1 was performed.

[0070] Comparative Example 2: LLZTO powder was directly and physically blended with PEGDA, LiTFSI and AIBN (the dosage relationship is the same as in Example 1), coated into a film, cured at 60°C, and then assembled into a coin cell with the positive electrode NMC811 and the lithium foil metal negative electrode in an inert atmosphere glove box.

[0071] Experimental Example: The batteries prepared in each embodiment and comparative example were tested, and the basic physical and electrochemical properties are shown in Table 1. In the electrochemical performance test, the batteries were cycled under 0.5C conditions, and the performance is shown in Table 2. In addition, rate tests were performed on each battery, with the rate increased from 0.2C to 0.5C, then to 1.0C, and then decreased back to 0.2C, corresponding to the values ​​in the four columns of Table 3, and the performance is shown in Table 3.

[0072] Table 1

[0073] As can be seen from Table 1: (1) Bulk conductivity: The conductivity of the embodiment is on the same order of magnitude as that of Comparative Example 1, and is significantly higher than that of Comparative Example 2, which is a traditional blend; it can be seen that the gradient structure of the present invention perfectly preserves the continuous ion conduction trunk of LLZTO, and is not cut off by the polymer phase as in Comparative Example 2.

[0074] (2) Interface impedance: The interface impedance of the embodiment is extremely low, which is reduced by about 95% compared to the rigid Comparative Example 1 and by about 66% compared to Comparative Example 2; this fully demonstrates the great advantage of the in-situ formed polymer interface layer in achieving intimate “surface contact”.

[0075] (3) Lithium-ion transference number: The transference number of the example is much higher than that of Comparative Example 2. This is due to the high transference number characteristics of the LLZTO framework and the combined contribution of the "salt-coated polymer" environment in the solution of step (2) of the example. A high transference number means smaller polarization, which is beneficial for the rapid charging and discharging of the battery.

[0076] (4) Mechanical properties: The modulus of the embodiment is much higher than that of Comparative Example 2, and it has the ability to rigidly block dendrites. At the same time, it is not completely rigid like Comparative Example 1, and has a certain degree of toughness to adapt to volume changes during cycling.

[0077] Table 2

[0078] As shown in Table 2, the battery in the Example exhibits the highest initial capacity and the best cycle stability. The rapid degradation of Comparative Example 1 stems from its large, unstable interfacial impedance, leading to active material deactivation and exacerbated side reactions. The degradation of Comparative Example 2 is mainly due to its lower ionic conductivity and mechanical strength, which may result in uneven local current density and micro-short circuits. Furthermore, the Example retains approximately 90% of its capacity after 200 cycles, demonstrating the high stability of its structure and interface.

[0079] Table 3

[0080] As shown in Table 3, the examples exhibited higher reversible capacities than the comparative examples at all rates, especially at the high rate of 1.0C, where their capacity was significantly higher than both comparative examples. This is attributed to the high bulk conductivity and low interfacial impedance of the examples, which enabled lithium ions to be rapidly transported within the electrolyte and smoothly pass through the interface. In contrast, the performance of Comparative Example 1 decreased sharply at high rates, mainly because its large interfacial impedance became a bottleneck for ion transport; Comparative Example 2 was limited by its relatively low bulk conductivity.

[0081] Furthermore, the present invention also conducted critical current density (CCD) tests on Example 1 and the comparative example, and the results are as follows: a) Example 1: >1.5mA / cm 2 (Combining excellent interface and rigid framework, effectively suppressing dendrites). b) Comparative Example 1: ~0.4 mA / cm 2 (It typically fails due to interfacial contact failure before reaching higher currents). c) Comparative Example 2: ~0.8 mA / cm 2(Due to insufficient mechanical strength, dendrites can easily penetrate).

[0082] Through the above systematic examples and comparative comparisons, the following conclusive conclusions can be drawn: (1) This invention successfully constructs a high-performance functionally graded composite electrolyte. Its unique structure enables the three key indicators of high bulk ionic conductivity, low interfacial impedance and high mechanical strength to be achieved synergistically, rather than compromised, in a simple process for the first time.

[0083] (2) The battery performance of the present invention surpasses that of existing technologies in all aspects. It exhibits significant advantages in cycle life, rate performance, and safety window (CCD).

[0084] (3) The method provided by the present invention is simple, low-cost and compatible with existing production lines, providing a promising new path to solve the commercialization problem of all-solid-state batteries.

[0085] Although the present invention has been illustrated and described with specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and scope of the present invention; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such substitutions and modifications that fall within the scope of the present invention are included in the appended claims.

Claims

1. A method for preparing a solid-state battery, characterized in that, Includes the following steps: Porous green bodies were obtained by pressing with oxide solid electrolytes; Prepare a dispersion of a polymer precursor containing a thermally polymerizable monomer, a lithium salt, and an initiator; In a vacuum environment, the porous green body is immersed in the dispersion and then transferred to a non-vacuum environment to separate and obtain the electrolyte precursor. The electrolyte precursor and electrodes are assembled to obtain a battery precursor, which is then subjected to isothermal treatment to obtain a solid-state battery.

2. The method for preparing a solid-state battery according to claim 1, characterized in that, The porosity of the porous green body is 10%~40%; Preferably, the pressing pressure is 100MPa~400MPa.

3. The method for preparing a solid-state battery according to claim 1, characterized in that, The thermopolymerizable monomer includes at least one of acrylate monomers, vinyl monomers, and epoxy monomers; And / or, the oxide solid electrolyte includes at least one of garnet-type solid electrolyte, NASICON-type solid electrolyte, and perovskite-type solid electrolyte; And / or, the lithium salt includes at least one of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium fluorosulfonyl(trifluoromethanesulfonyl)imide, lithium bis(oxalato)borate, lithium di(fluorooxalato)borate, and lithium hexafluorophosphate.

4. The method for preparing a solid-state battery according to claim 3, characterized in that, The acrylate monomers include at least one of polyethylene glycol methyl ether acrylate, polyethylene glycol diacrylate, trimethylolpropane triacrylate, methoxy polyethylene glycol methacrylate, acrylonitrile, and pentaerythritol tetraacrylate. And / or, the vinyl monomers include at least one of ethylene carbonate, vinylene carbonate, allyl methyl carbonate, ethyl propylene carbonate, diallyl carbonate, diallyl pyrocarbonate, bis(2-methylallyl) carbonate, cyanoethyl acrylate, N-vinylpyrrolidone, 1,3-butanediol divinyl ether, and vinylene carbonate. And / or, the epoxy monomers include at least one of ethylene oxide, propylene oxide, epichlorohydrin, ethylene glycol diglycidyl ether, allyl glycidyl ether, 1,4-butanediol diglycidyl ether, glycerol propoxy triglycidyl ether, and vinylcyclohexene dioxide.

5. The method for preparing a solid-state battery according to claim 1, characterized in that, The temperature of the constant temperature treatment is 50℃~70℃, and the time of the constant temperature treatment is 6h~12h.

6. The method for preparing a solid-state battery according to claim 1, characterized in that, The molar ratio of the initiator to the thermally polymerizable monomer is 0.1% to 5.0%. And / or, the concentration of the lithium salt in the dispersion is 1 mol / L to 5 mol / L.

7. The method for preparing a solid-state battery according to claim 1, characterized in that, The vacuum level of the vacuum environment is ≤1 kPa; And / or, the pressure of the non-vacuum environment is ≥101.325 kPa.

8. A solid-state battery prepared by the method of any one of claims 1 to 7.

9. The solid-state battery according to claim 8, characterized in that, The solid-state battery includes electrodes and a solid electrolyte disposed between the electrodes; The solid electrolyte includes a porous framework and a cross-linked polymer supported on the porous framework; The concentration of the crosslinked polymer increases in the direction from the porous framework to the electrode surface.

10. Use of the method for preparing a solid-state battery as described in any one of claims 1 to 7 in the field of solid-state batteries.

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