In-situ polymerized dioxolane polymer solid-state electrolyte, fluorine-containing magnesium interface layer, battery, and preparation method

Abstract

An in-situ polymerization dioxolane polymer solid electrolyte, a fluorinated magnesium interface layer, a battery and a preparation method thereof, 1,3-dioxolane, lithium salt and magnesium-containing montmorillonite are uniformly mixed to obtain a mixed solution, then the mixed solution is immersed into a support, matched with a lithium metal negative electrode and a positive electrode to assemble a full battery, and placed for a period of time, and a polymerized dioxolane composite polymer solid electrolyte is prepared through an in-situ polymerization reaction. The magnesium ions spontaneously aggregated on the surface of the montmorillonite compete with the lithium salt anions for coordination, regulate the coordination environment of lithium ions in the electrolyte, increase the number of free lithium ions, and thus improve the ionic conductivity of the electrolyte. In addition, the magnesium ions and the lithium salt anion ligands decompose at the positive and negative electrode interface to participate in the formation of the interface layer, producing an inorganic component-rich interface layer (CEI and SEI) containing fluorinated magnesium, which has a high Young's modulus and fast lithium ion transport kinetics, is beneficial to the rapid transport of lithium ions and improves the stability of the electrolyte and the positive and negative electrode interface, and thus has a good application prospect.

Description

Technical Field

[0001] This invention relates to battery technology, and in particular to an in-situ polymerized dioxolane polymer solid electrolyte, a magnesium fluoride interface layer, a battery, and a method for preparing the same. Background Technology

[0002] Since their invention, lithium-ion batteries (LIBs) have been widely used in consumer electronics, energy storage, and new energy fields due to their numerous advantages, including low self-discharge, no memory effect, high energy density, and long cycle life. With increasing societal demands, the new energy sector has entered a new stage of development. Electric vehicles (EVs) urgently require batteries with higher safety and longer driving range; therefore, lithium-ion batteries are developing towards higher energy density, longer lifespan, and greater safety. However, the capacity of traditional graphite anodes is currently approaching its theoretical limit, which restricts further increases in the energy density of lithium batteries. Lithium metal and NCM811 have a capacity of 3860 mA·h·g. –1 and more than 200 mA·h·g –1 High theoretical capacity makes them among the most promising anode and cathode materials for achieving high energy density. However, liquid lithium-ion batteries prepared with organic liquid electrolytes suffer from numerous drawbacks, including severe interfacial reactions and poor safety, limiting their practical application. For example, lithium dendrite growth can lead to short circuits, thermal runaway, and even explosions, while severe side reactions at the electrolyte-high-voltage cathode interface cause rapid capacity decay. Solid-state lithium-ion batteries (ASSLBs), theoretically possessing high energy density and safety, are the most promising alternative to liquid lithium-ion batteries.

[0003] As a type of solid-state electrolyte, in-situ polymerized solid-state electrolytes (SPEs) have advantages such as ease of preparation, good electrode / electrolyte integration, and good interfacial contact, making them one of the most studied solid-state electrolytes. However, problems such as poor mechanical properties, severe lithium dendrite growth, and severe side reactions when matched with high-voltage cathodes limit their practical application. For example, although polydioxanone (PDOL) polymer-based solid-state electrolytes obtained by in-situ polymerization of dioxanone monomer (DOL) have good elasticity and plasticity and high ionic conductivity, they are difficult to suppress lithium dendrite growth and are unstable with high-voltage cathodes, making it difficult to match high-voltage cathodes (such as high-nickel cathodes) for stable operation at high voltages. These problems lead to severe dendrite growth and severe side reactions on the cathode side in batteries assembled with in-situ polymerized solid-state electrolytes, making it difficult to achieve stable operation. Therefore, constructing a stable electrolyte / anode interface is imperative.

[0004] It should be noted that the information disclosed in the background section above is only for understanding the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0005] The main objective of this invention is to overcome the deficiencies in the above-mentioned background technology and provide an in-situ polymerized dioxolane polymer solid electrolyte, a magnesium fluoride interface layer, a battery, and a method for preparing the same.

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

[0007] A method for preparing an in-situ polymerized dioxolane composite polymer solid electrolyte includes: mixing 1,3-dioxolane, 1-4M lithium salt and 2-15 wt.% magnesium-containing montmorillonite to obtain a mixed solution, then immersing the mixed solution into a support, matching and assembling it with a lithium metal anode and cathode to form a full cell, allowing it to stand for a period of time, and obtaining the polymerized dioxolane composite polymer solid electrolyte through an in-situ polymerization reaction.

[0008] Furthermore:

[0009] The support is selected from at least one of PP membrane, PE membrane, PVDF (polyvinylidene fluoride) membrane, PAN (polyacrylonitrile) membrane, LATP (lithium aluminum titanium phosphate) electrospinning matrix, LLZO (lithium lanthanum zirconium oxide) electrospinning matrix, and BTO (barium titanate) electrospinning matrix.

[0010] The lithium salt is selected from at least one of lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethyl)sulfonyl)imide (LiTFSI), lithium difluorooxalate borate (LiDFOB), and lithium hexafluorophosphate (LiPF6).

[0011] A method for constructing a magnesium fluoride-rich inorganic interface layer includes: uniformly mixing 1,3-dioxolane, 1-4M lithium salt, and 2-15 wt.% magnesium-containing montmorillonite to obtain a mixed solution; immersing the mixed solution in a support; assembling it into a full cell by matching it with a lithium metal anode and cathode; allowing it to stand for a period of time; and obtaining a polymerized dioxolane composite polymer solid electrolyte through an in-situ polymerization reaction; and performing electrochemical cycling, where magnesium ions and lithium salt anions react at the interface of the cathode and anode to form an inorganic component-rich interface layer containing magnesium fluoride.

[0012] An in-situ polymerized dioxolane composite polymer solid electrolyte is prepared using the same preparation method.

[0013] A magnesium fluoride-rich inorganic interface layer is prepared using the method described above for constructing a magnesium fluoride-rich inorganic interface layer.

[0014] A battery preparation method includes: uniformly mixing 1,3-dioxolane, 1-4M lithium salt and 2-15 wt.% magnesium-containing montmorillonite to obtain a mixed solution; then immersing the mixed solution into a support; assembling it with a lithium metal anode and cathode to form a full battery; allowing it to stand for a period of time; and obtaining a polymerized dioxolane composite polymer solid electrolyte through an in-situ polymerization reaction; and performing electrochemical cycling, in which magnesium ions and lithium salt anions react at the interface of the cathode and anode to form an inorganic component-rich interface layer containing magnesium fluoride.

[0015] A battery is prepared using the aforementioned battery preparation method containing magnesium fluoride-rich inorganic interface layer.

[0016] A battery comprising either the in-situ polymerized solid electrolyte or the magnesium fluoride-rich inorganic interface layer.

[0017] A battery includes a lithium metal anode, a cathode, and a polymeric dioxolane composite solid electrolyte formed on a support, wherein the polymeric dioxolane composite solid electrolyte is formed by in-situ polymerization of 1,3-dioxolane monomers initiated by magnesium ions in magnesium-containing montmorillonite, and a magnesium fluoride-rich inorganic component interface layer is formed at the contact interface between the lithium metal anode and / or cathode and the polymeric dioxolane composite solid electrolyte; preferably, the cathode is a high-nickel cathode.

[0018] The present invention has the following beneficial effects:

[0019] This invention provides an innovative in-situ polymerized dioxolane solid electrolyte, a magnesium fluoride interface layer, a battery, and its preparation method. The preparation method involves adding magnesium-containing montmorillonite to a solution of dioxolane and lithium salt, and using magnesium ions to initiate a polymerization reaction at room temperature to obtain a polydioxolane (PDOL) composite polymer solid electrolyte. This electrolyte has a simple preparation process, mild conditions, low cost, and strong adaptability and universality. Due to the competitive coordination between magnesium ions and lithium salt anions, the lithium ion coordination environment inside the electrolyte is regulated, effectively increasing the number of free lithium ions and thus significantly improving the electrolyte's ionic conductivity. Furthermore, the decomposition of magnesium ions and lithium salt anion ligands at the positive and negative electrode interfaces participates in the formation of the interface layer, producing a magnesium fluoride-rich inorganic component interface layer (CEI and SEI). In addition to traditional inorganic components such as LiF, Li₂CO₃, Li₂S, and Li₃N, this interface layer also contains a magnesium-containing inorganic component, Mg₂F. The introduction of magnesium fluoride, due to its high Young's modulus and low lithium-ion transport barrier, significantly enhances the mechanical stability and lithium-ion transport capacity of the interface layer, achieving uniform lithium deposition / stripping on the negative electrode side and excellent oxidation resistance on the positive electrode side. This composite polymer solid electrolyte exhibits a high lithium-ion transference number of 0.60 and a wide electrochemical window of 5.3V. Li / Li symmetric batteries based on this electrolyte can cycle stably for over 6000 hours, while Li / LiNi... 0.8 Co 0.1 Mn 0.1 When used in conjunction with O2 batteries, this invention exhibits excellent rate performance and cycle stability exceeding 500 cycles, demonstrating promising application prospects in the battery field. Therefore, this invention not only improves the performance of solid-state electrolytes but also enhances battery safety and cycle stability, which is of great significance for promoting the development of high-energy-density, long-life, and safer battery technologies.

[0020] Other beneficial effects of the embodiments of the present invention will be further described below. Attached Figure Description

[0021] Figure 1 Zeta potential test of montmorillonite in an embodiment of the present invention.

[0022] Figure 2 This is a Zeta potential test of montmorillonite in an embodiment of the present invention.

[0023] Figure 3 Raman spectroscopy tests were performed on the PDE and MPDE of the comparative examples and embodiments of the present invention.

[0024] Figure 4 The ionic conductivity of PDE and MPDE in the comparative examples and embodiments of this invention was tested.

[0025] Figure 5 Electrochemical window LSV testing of PDE and MPDE in comparative examples and embodiments of the present invention.

[0026] Figure 6 XPS composition analysis of the SEI of lithium metal surfaces formed based on PDE and MPDE for comparative examples and embodiments of the present invention.

[0027] Figure 7 XPS composition analysis of CEI on NCM811 surfaces formed based on PDE and MPDE for comparative examples and embodiments of the present invention.

[0028] Figure 8 This is a comparison diagram of the Young's modulus of the interface layers SEI and CEI formed based on PDE and MPDE in the comparative examples and embodiments of the present invention.

[0029] Figure 9 The lithium-ion migration barriers of lithium fluoride and magnesium fluoride in the comparative examples and embodiments of the present invention.

[0030] Figure 10 This invention provides comparative examples and embodiments of the long-cycle performance of in-situ polymerized lithium-ion symmetric batteries based on PDE and MPDE.

[0031] Figure 11 The rate performance test curves of the in-situ polymerized full cells based on PDE and MPDE in the comparative examples and embodiments of the present invention are shown.

[0032] Figure 12 The test curves show the long-cycle performance of PDE and MPDE-based in-situ polymerized full cells in comparative and embodiment examples of the present invention. Detailed Implementation

[0033] The embodiments of the present invention will be described in detail below. It should be emphasized that the following description is merely exemplary and not intended to limit the scope and application of the present invention.

[0034] According to an embodiment of the present invention, a method for preparing an in-situ polymerized dioxolane composite polymer solid electrolyte includes: mixing 1,3-dioxolane, 1-4M lithium salt and 2-15 wt.% magnesium-containing montmorillonite to obtain a mixed solution, then immersing the mixed solution in a support, matching and assembling it with a lithium metal anode and cathode to form a full cell, allowing it to stand for a period of time, and obtaining the polymerized dioxolane composite polymer solid electrolyte through an in-situ polymerization reaction.

[0035] A method for constructing a magnesium fluoride-rich inorganic interface layer includes: uniformly mixing 1,3-dioxolane, 1-4M lithium salt, and 2-15 wt.% magnesium-containing montmorillonite to obtain a mixed solution; immersing the mixed solution in a support; assembling it into a full cell by matching it with a lithium metal anode and cathode; allowing it to stand for a period of time; and obtaining a polymerized dioxolane composite polymer solid electrolyte through an in-situ polymerization reaction; and performing electrochemical cycling, where magnesium ions and lithium salt anions react at the interface of the cathode and anode to form an inorganic component-rich interface layer containing magnesium fluoride.

[0036] A battery preparation method includes: uniformly mixing 1,3-dioxolane, 1-4M lithium salt and 2-15 wt.% magnesium-containing montmorillonite to obtain a mixed solution; then immersing the mixed solution into a support; assembling it with a lithium metal anode and cathode to form a full battery; allowing it to stand for a period of time; and obtaining a polymerized dioxolane composite polymer solid electrolyte through an in-situ polymerization reaction; and performing electrochemical cycling, in which magnesium ions and lithium salt anions react at the interface of the cathode and anode to form an inorganic component-rich interface layer containing magnesium fluoride.

[0037] The present invention also provides an in-situ polymerized dioxolane composite polymer solid electrolyte, a magnesium fluoride-rich inorganic interface layer, and a battery prepared by the above method.

[0038] The battery includes a lithium metal anode, a cathode, and a polymeric dioxolane composite solid electrolyte formed on a support. The polymeric dioxolane composite solid electrolyte is formed by in-situ polymerization of 1,3-dioxolane monomers initiated by magnesium ions in magnesium-containing montmorillonite. Furthermore, an inorganic interface layer containing magnesium fluoride is formed at the interface between the lithium metal anode and / or cathode and the polymeric dioxolane composite solid electrolyte. Preferably, the cathode is a high-nickel cathode.

[0039] The mechanism and process of magnesium ion-initiated in-situ polymerization of DOL are shown in equation (Ⅰ):

[0040]

[0041] The in-situ polymerized solid electrolyte and solid-state battery characteristics are as follows: Figure 1 As shown.

[0042] According to some embodiments of the present invention, the dioxolane, the lithium salt and the magnesium-containing montmorillonite are mixed evenly in a certain proportion to obtain a mixed solution. An appropriate amount of the above mixed solution is dropped onto a support, and the mixture is allowed to stand at room temperature for a period of time to polymerize in situ to obtain a composite polymer solid electrolyte. The obtained solid electrolyte is matched with a lithium metal anode and a high-voltage cathode. During physical contact and electrochemical charge and discharge, in-situ chemical and electrochemical reactions occur to generate an interface layer rich in inorganic components containing magnesium fluoride.

[0043] In this embodiment of the invention, magnesium-containing montmorillonite is added to a solution of dioxolane (DOL) and lithium salt. Magnesium ions initiate in-situ polymerization at room temperature to obtain a polydioxolane (PDOL) composite polymer solid electrolyte. Magnesium ions spontaneously aggregate on the montmorillonite surface compete with lithium salt anions for coordination, regulating the lithium ion coordination environment within the electrolyte, increasing the number of free lithium ions, and thus improving the ionic conductivity of the electrolyte. Furthermore, magnesium ions and lithium salt anion ligands decompose at the positive and negative electrode interfaces, participating in the formation of an interface layer, generating a magnesium fluoride-rich inorganic component interface layer (CEI and SEI). This magnesium fluoride-rich inorganic interface layer possesses a high Young's modulus and rapid lithium-ion transport dynamics, which is beneficial for rapid lithium-ion transport and improves the stability of the electrolyte and the positive and negative electrode interfaces. This composite polymer solid electrolyte exhibits a high lithium-ion transference number of 0.60 and a wide electrochemical window of 5.3V. A Li / Li symmetric battery based on this composite polymer solid electrolyte can cycle stably for over 6000 hours, and a Li / LiNi... 0.8 Co 0.1 Mn 0.1 O2 batteries exhibit excellent rate performance and cycle stability exceeding 500 cycles, showing promising application prospects in the battery field.

[0044] In some embodiments, the support may be selected from one or more of PP membrane, PE membrane, PVDF (polyvinylidene fluoride) membrane, PAN (polyacrylonitrile) membrane, LATP (lithium aluminum titanium phosphate) electrospinning matrix, LLZO (lithium lanthanum zirconium oxide) electrospinning matrix, and BTO (barium titanate) electrospinning matrix. The lithium salt may be selected from one or more of lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium difluorooxalate borate (LiDFOB), and lithium hexafluorophosphate (LiPF6).

[0045] The in-situ polymerized composite solid electrolyte provided in this application comprises polydioxolane, a support, a lithium salt, and magnesium-containing montmorillonite. It exhibits uniform polymer segment distribution, high ionic conductivity, high lithium-ion transference number (0.60), high mechanical strength, and a wide electrochemical window (5.3V), making it well-suited for use with lithium metal anodes and NCM811 cathodes, thus possessing significant application value. The preparation method provided in this application is simple, with mild in-situ reaction conditions, low cost, and strong adaptability and versatility. The prepared composite solid electrolyte and the magnesium fluoride-rich inorganic component interface layer can be applied to lithium metal / high-nickel ternary batteries to improve the stability of the solid electrolyte to lithium metal and high-voltage cathodes.

[0046] The following describes specific embodiments of the present invention.

[0047] A magnesium ion-initiated in-situ polymerization of dioxolane polymer solid electrolyte, magnesium fluoride interface layer, battery, and preparation method thereof.

[0048] Example 1

[0049] This embodiment provides a composite solid electrolyte (MPDE composite solid electrolyte), which is prepared according to the following steps:

[0050] Step S1: First, weigh 2583 mg LiTFSI (lithium bis(trifluoromethanesulfonyl)imide) and 144 mg LiDFOB (lithium difluorooxalate borate) under an inert atmosphere and place them in a stirring flask. Add 5 mL of DOL (1,3-dioxolane) and stir on a small stirrer at room temperature for more than 10 minutes to completely dissolve and obtain a uniform transparent solution.

[0051] Step S2: Add 100 mg of montmorillonite to the transparent solution obtained in step S1, and stir at room temperature for more than 10 minutes to obtain a mixture.

[0052] Step S3: The mixture obtained in step S2 is dropped onto the PP membrane, placed in a glove box and left to stand at room temperature for 24 hours. In-situ polymerization is carried out to obtain the MPDE composite solid electrolyte membrane, which is then cut to the appropriate size, dried and stored under an inert atmosphere for later use.

[0053] Comparative Example 1

[0054] This comparative example provides an in-situ polymerized solid electrolyte (PDE composite solid electrolyte), which is prepared according to the following steps:

[0055] Step S1: First, weigh 2583 mg LiTFSI (lithium bis(trifluoromethanesulfonyl)imide) and 144 mg LiDFOB (lithium difluorooxalate borate) under an inert atmosphere and place them in a stirring flask. Add 5 mL of DOL (1,3-dioxolane) and stir on a small stirrer at room temperature for more than 10 minutes to completely dissolve and obtain a uniform transparent solution.

[0056] Step S2: Add 100 mg of LiPF6 (lithium hexafluorophosphate) to the transparent solution obtained in step S1, and stir at room temperature for more than 10 minutes to obtain a homogeneous solution.

[0057] Step S3: The solution obtained in step S2 is dropped onto the PP membrane, placed in a glove box and left to stand at room temperature for 24 hours to obtain a PDE solid electrolyte membrane through in-situ polymerization. The membrane is then cut to the appropriate size, dried under an inert atmosphere, and stored for later use.

[0058] Figure 2 The zeta potential of montmorillonite was measured. The result was positive, indicating that magnesium ions spontaneously aggregated on the surface of montmorillonite, making the whole material positively charged.

[0059] Figure 3Raman spectroscopy tests were performed on PDE and MPDE. The Raman shift of the MPDE sample corresponding to the TFSI anion shifted to higher wavenumbers, indicating that magnesium ions in montmorillonite compete for coordination with TFSI anions.

[0060] Figure 4 The ionic conductivity of PDE and MPDE was measured. In MPDE, magnesium ions compete with lithium salt anions for coordination, generating more free lithium ions and increasing ionic conductivity.

[0061] Figure 5 Electrochemical window LSV measurements were performed for PDE and MPDE. MPDE exhibited a wider electrochemical window of 5.3V.

[0062] Example 2

[0063] This embodiment provides an assembled battery and a magnesium fluoride-rich inorganic interface layer, assembled according to the following steps:

[0064] Step S1, Preparation of positive electrode slurry: First, weigh 100 mg of PVDF (binder) and place it in a stirred flask, add 1 mL of NMP (N-methylpyrrolidone), and stir on a small stirrer for 1 hour until the PVDF is completely dissolved. Then add 100 mg of SuperP (conductive carbon black) and 1 mL of NMP, stir at room temperature for 1 hour, add 800 mg of NCM811 (ternary material nickel-cobalt-manganese) active material and 1.5 mL of NMP, and stir at room temperature for more than 6 hours.

[0065] Step S2, Preparation of positive electrode: The positive electrode slurry obtained in step S1 is coated on aluminum foil, dried at 80°C for more than 6 hours, cut into appropriate size to obtain NCM811 positive electrode, and placed in a vacuum oven for drying and storage.

[0066] Step S3: First, weigh 2583 mg of LiTFSI (bis(trifluoromethanesulfonyl)) under an inert atmosphere. Lithium amine (LiDFOB) and 144 mg of LiDFOB (lithium difluorooxalate borate) were placed in a stirred flask, and 5 mL of DOL (1,3-dioxolane) was added. The mixture was stirred on a small stirrer at room temperature for at least 10 minutes to completely dissolve the precipitate and obtain a homogeneous, transparent solution. 100 mg of montmorillonite was then added to the transparent solution obtained in step S1, and the mixture was stirred at room temperature for at least 10 minutes to obtain a mixed solution.

[0067] Step S4: Following the full-cell assembly process, the NCM811 cathode obtained in step S2, the PP separator, the mixture obtained in step S3, and lithium metal are assembled into a full cell. The full cell is left to stand at room temperature for 24 hours to obtain an in-situ polymerized solid-state MPDE full cell. The full cell is then charged and discharged three times at a current density of 0.1C to construct a magnesium fluoride-rich inorganic interface layer at the positive and negative electrode interfaces.

[0068] Following the full-cell assembly process, the NCM811 cathode obtained in step S2, the PP separator, the mixture obtained in step S2 of Comparative Example 1, and lithium metal were assembled into a full cell. The full cell was left to stand at room temperature for 24 hours to obtain an in-situ polymerized solid-state PDE full cell. The full cell was then subjected to three charge-discharge cycles at a current density of 0.1C to construct a common interface layer at the positive and negative electrode interfaces.

[0069] Step S5: Following the symmetric cell assembly process, the PP separator and the mixture obtained in step S3 are sandwiched between two layers of lithium metal to assemble a lithium-lithium symmetric cell. The symmetric cell is left to stand at room temperature for 24 hours to obtain an in-situ polymerized solid-state MPDE symmetric cell. The symmetric cell is then subjected to an A / cm² temperature of 0.1 mA. 2 0.1mAh / cm 2 After 30 cycles, a lithium metal anode containing magnesium fluoride and rich in inorganic SEI was constructed.

[0070] Following the symmetric cell assembly process, a PP separator and the mixture obtained in step S2 of Comparative Example 1 were sandwiched between two layers of lithium metal to assemble a lithium-lithium symmetric cell. The symmetric cell was left to stand at room temperature for 24 hours to obtain an in-situ polymerized solid-state PDE symmetric cell. The symmetric cell was then subjected to an A / cm² temperature of 0.1 mA. 2 0.1 mA h / cm 2 After 30 cycles, a lithium metal anode containing ordinary SEI was constructed.

[0071] Figure 6 XPS compositional analysis of the SEI on the lithium metal surface formed based on PDE and MPDE. Figure 7 XPS composition analysis of CEI on the NCM811 surface formed based on PDE and MPDE was performed. It was found that the MPDE-based interfacial layer contained less CO organic content compared to the PDE-based layer, indicating reduced interfacial decomposition of the MPDE electrolyte. Furthermore, the MPDE-formed interfacial layer contained a new magnesium fluoride component, which is beneficial for improving the mechanical strength and lithium-ion transport capacity of the interfacial layer, thus enhancing its protective effect on both the positive and negative electrodes.

[0072] Figure 8 This is a comparison of the Young's modulus of the SEI and CEI interface layers formed based on PDE and MPDE, respectively. The results show that magnesium fluoride has a higher Young's modulus than lithium fluoride. Due to the presence of magnesium fluoride, the Young's modulus of both the SEI and CEI formed based on MPDE electrolytes is significantly improved.

[0073] Figure 9 The lithium-ion migration barrier for lithium fluoride and magnesium fluoride was determined. The results showed that magnesium fluoride has a lower lithium-ion migration barrier than the conventional component lithium fluoride, which is beneficial for lithium-ion transport in the magnesium fluoride interface layer.

[0074] Figure 10 To assess the long-cycle performance of in-situ polymerized lithium-ion symmetric batteries based on PDE and MPDE. Results show that at room temperature and a current density of 0.1 mA cm⁻¹... –2 The surface capacity is 0.1mAh cm –2 Under these conditions, the Li / MPDE / Li battery can cycle stably for over 6000 hours and exhibits low overpotential. In contrast, the PDE-based symmetric battery has high overpotential and short cycle life, demonstrating the superiority of the magnesium fluoride-containing interface layer.

[0075] Figure 11 The figures show the rate performance test curves of full cells based on PDE and MPDE in-situ polymerization. As can be seen from the figures, the full cell assembled by matching MPDE with NCM811 cathode and lithium metal anode exhibits excellent rate performance, still achieving a capacity of 128 mAh / g at a current density of 0.5C at room temperature.

[0076] Figure 12 The figures show the long-cycle performance test curves of full cells based on in-situ polymerization of PDE and MPDE. As can be seen from the figures, the full cell assembled by matching MPDE with NCM811 cathode and lithium metal anode exhibits excellent cycle stability, and can stably cycle 500 times at room temperature and 0.1C with a capacity retention of 82.6%.

[0077] Example 3

[0078] This embodiment provides a battery assembly method, which involves assembling the battery according to the following steps:

[0079] Step S1, Preparation of positive electrode slurry: First, weigh 100 mg of PVDF (binder) and place it in a stirred flask, add 1 mL of NMP (N-methylpyrrolidone), and stir on a small stirrer for 1 hour until the PVDF is completely dissolved. Then add 100 mg of SuperP (conductive carbon black) and 1 mL of NMP, stir at room temperature for 1 hour, add 800 mg of NCM811 (ternary material nickel-cobalt-manganese) active material and 1.5 mL of NMP, and stir at room temperature for more than 6 hours.

[0080] Step S2, Preparation of positive electrode: The positive electrode slurry obtained in step S1 is coated on aluminum foil, dried at 80°C for more than 6 hours, cut into appropriate size to obtain NCM811 positive electrode, and placed in a vacuum oven for drying and storage.

[0081] Step S3: First, weigh 2583 mg of LiTFSI (lithium bis(trifluoromethanesulfonyl)imide) and 144 mg of LiDFOB (lithium difluorooxalate borate) into a stirred flask under an inert atmosphere. Add 5 mL of DOL (1,3-dioxolane) and stir on a small stirrer at room temperature for at least 10 minutes until completely dissolved to obtain a homogeneous, transparent solution. Add 100 mg of montmorillonite to the transparent solution obtained in step S1 and stir at room temperature for at least 10 minutes to obtain a mixed solution.

[0082] Step S4: Following the full-cell assembly process, the NCM811 cathode obtained in step S2, the PE separator, the mixture obtained in step S3, and lithium metal are assembled into a full cell. The full cell is then left to stand at room temperature for 24 hours to obtain an in-situ polymerized solid-state full cell.

[0083] Example 4

[0084] This embodiment provides a battery assembly method, which involves assembling the battery according to the following steps:

[0085] Step S1, Preparation of positive electrode slurry: First, weigh 100 mg of PVDF (binder) and place it in a stirred flask, add 1 mL of NMP (N-methylpyrrolidone), and stir on a small stirrer for 1 hour until the PVDF is completely dissolved. Then add 100 mg of SuperP (conductive carbon black) and 1 mL of NMP, stir at room temperature for 1 hour, add 800 mg of NCM811 (ternary material nickel-cobalt-manganese) active material and 1.5 mL of NMP, and stir at room temperature for more than 6 hours.

[0086] Step S2, Preparation of positive electrode: The positive electrode slurry obtained in step S1 is coated on aluminum foil, dried at 80°C for more than 6 hours, cut into appropriate size to obtain NCM811 positive electrode, and placed in a vacuum oven for drying and storage.

[0087] Step S3: First, weigh 2583 mg of LiTFSI (lithium bis(trifluoromethanesulfonyl)imide) and 144 mg of LiDFOB (lithium difluorooxalate borate) into a stirred flask under an inert atmosphere. Add 5 mL of DOL (1,3-dioxolane) and stir on a small stirrer at room temperature for at least 10 minutes until completely dissolved to obtain a homogeneous, transparent solution. Add 100 mg of montmorillonite to the transparent solution obtained in step S1 and stir at room temperature for at least 10 minutes to obtain a mixed solution.

[0088] Step S4: Following the full-cell assembly process, the NCM811 cathode obtained in step S2, the PVDF separator, the mixture obtained in step S3, and lithium metal are assembled into a full cell. The full cell is then left to stand at room temperature for 24 hours to obtain an in-situ polymerized solid-state full cell.

[0089] Example 5

[0090] This embodiment provides a battery assembly method, which involves assembling the battery according to the following steps:

[0091] Step S1, Preparation of positive electrode slurry: First, weigh 100 mg of PVDF (binder) and place it in a stirred flask, add 1 mL of NMP (N-methylpyrrolidone), and stir on a small stirrer for 1 hour until the PVDF is completely dissolved. Then add 100 mg of SuperP (conductive carbon black) and 1 mL of NMP, stir at room temperature for 1 hour, add 800 mg of NCM811 (ternary material nickel-cobalt-manganese) active material and 1.5 mL of NMP, and stir at room temperature for more than 6 hours.

[0092] Step S2, Preparation of positive electrode: The positive electrode slurry obtained in step S1 is coated on aluminum foil, dried at 80°C for more than 6 hours, cut into appropriate size to obtain NCM811 positive electrode, and placed in a vacuum oven for drying and storage.

[0093] Step S3: First, weigh 2583 mg of LiTFSI (lithium bis(trifluoromethanesulfonyl)imide) and 144 mg of LiDFOB (lithium difluorooxalate borate) into a stirred flask under an inert atmosphere. Add 5 mL of DOL (1,3-dioxolane) and stir on a small stirrer at room temperature for at least 10 minutes until completely dissolved to obtain a homogeneous, transparent solution. Add 100 mg of montmorillonite to the transparent solution obtained in step S1 and stir at room temperature for at least 10 minutes to obtain a mixed solution.

[0094] Step S4: Following the full-cell assembly process, the NCM811 cathode obtained in step S2, the LLZTO support, the mixture obtained in step S3, and lithium metal are assembled into a full cell. The full cell is then left to stand at room temperature for 24 hours to obtain an in-situ polymerized solid-state full cell.

[0095] Example 6

[0096] This embodiment provides a battery assembly method, which involves assembling the battery according to the following steps:

[0097] Step S1, Preparation of positive electrode slurry: First, weigh 100 mg of PVDF (binder) and place it in a stirred flask, add 1 mL of NMP (N-methylpyrrolidone), and stir on a small stirrer for 1 hour until the PVDF is completely dissolved. Then add 100 mg of SuperP (conductive carbon black) and 1 mL of NMP, stir at room temperature for 1 hour, add 800 mg of NCM811 (ternary material nickel-cobalt-manganese) active material and 1.5 mL of NMP, and stir at room temperature for more than 6 hours.

[0098] Step S2, Preparation of positive electrode: The positive electrode slurry obtained in step S1 is coated on aluminum foil, dried at 80°C for more than 6 hours, cut into appropriate size to obtain NCM811 positive electrode, and placed in a vacuum oven for drying and storage.

[0099] Step S3: First, weigh 2583 mg of LiTFSI (lithium bis(trifluoromethanesulfonyl)imide) and 144 mg of LiDFOB (lithium difluorooxalate borate) into a stirred flask under an inert atmosphere. Add 5 mL of DOL (1,3-dioxolane) and stir on a small stirrer at room temperature for at least 10 minutes until completely dissolved to obtain a homogeneous, transparent solution. Add 100 mg of montmorillonite to the transparent solution obtained in step S1 and stir at room temperature for at least 10 minutes to obtain a mixed solution.

[0100] Step S4: Following the full-cell assembly process, the NCM811 cathode obtained in step S2, the BTO support, the mixture obtained in step S3, and lithium metal are assembled into a full cell. The full cell is then left to stand at room temperature for 24 hours to obtain an in-situ polymerized solid-state full cell.

[0101] In summary, this invention presents an in-situ polymerized dioxolane (DOL) solid electrolyte, a magnesium fluoride interface layer, a battery, and a method for their preparation. By adding magnesium-containing montmorillonite to a solution of dioxolane (DOL) and lithium salt, and utilizing magnesium ions to initiate an in-situ polymerization reaction at room temperature, a polydioxolane (PDOL) composite polymer solid electrolyte was successfully prepared. This process is not only simple but also features mild in-situ reaction conditions, low cost, and strong adaptability and versatility. This allows the prepared composite solid electrolyte and the magnesium fluoride-rich inorganic component interface layer to be widely used in lithium metal / high-nickel ternary batteries, thereby improving the stability of the solid electrolyte to lithium metal and high-voltage cathodes.

[0102] Within the electrolyte, magnesium ions spontaneously aggregate on the montmorillonite surface compete for coordination with lithium salt anions, effectively regulating the lithium ion coordination environment, increasing the number of free lithium ions, and thus improving the electrolyte's ionic conductivity. Furthermore, the separation of magnesium ions and lithium salt anion ligands at the positive and negative electrode interfaces... The solution participated in the formation of the interface layer, resulting in magnesium fluoride-rich... Inorganic component interface layers (CEI and SEI) This magnesium fluoride-rich inorganic interface layer exhibits high Young's modulus and rapid lithium-ion transport dynamics, which is beneficial for the rapid transport of lithium ions and improves the stability of the electrolyte and positive and negative electrode interfaces.

[0103] This composite polymer solid electrolyte exhibits a high lithium-ion transference number of 0.60 and a wide electrochemical window of 5.3V, enabling Li / Li symmetric batteries based on this electrolyte to cycle stably for over 6000 hours, while Li / LiNi... 0.8 Co 0.1 Mn 0.1 When used with O2 batteries, it exhibits excellent rate performance and cycle stability of over 500 cycles, demonstrating promising application prospects in the battery field.

[0104] The interface layer prepared in this invention is a magnesium fluoride-rich inorganic SEI / CEI on the surface of a lithium metal anode / high-nickel cathode. It contains not only traditional inorganic components such as LiF, Li₂CO₃, Li₂S, and Li₃N, but also magnesium-containing inorganic components such as Mg₂F. The introduction of magnesium fluoride, due to its high Young's modulus and low lithium-ion transport barrier, greatly enhances the mechanical stability and lithium-ion transport capacity of the interface layer, achieving uniform lithium deposition / stripping on the anode side and excellent oxidation resistance on the cathode side. Therefore, the composite solid electrolyte based on this magnesium fluoride-rich inorganic interface layer, matched with a lithium metal anode, exhibits long-term cycling stability, and the lithium-lithium symmetric battery can cycle stably for over 6000 hours. The full cell formed by matching and assembling with a lithium metal anode and an NCM811 cathode exhibits excellent rate and cycle performance at room temperature, further demonstrating its promising application prospects in the battery field.

[0105] The above description provides a further detailed explanation of the present invention in conjunction with specific / preferred embodiments, and it should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various substitutions or modifications can be made to these described embodiments without departing from the concept of the present invention, and all such substitutions or modifications should be considered within the scope of protection of the present invention. In the description of this specification, the reference to terms such as "an embodiment," "some embodiments," "preferred embodiment," "example," "specific example," or "some examples," etc., indicates that the specific features, structures, materials, or characteristics described in connection with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples. Without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification and the features of different embodiments or examples. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions, and modifications can be made herein without departing from the scope of protection of the patent application.

Claims

1. A method for preparing an in-situ polymerized dioxolane composite solid electrolyte, characterized in that, include: A mixture of 1,3-dioxolane, 1-4M lithium salt and 2-15 wt.% magnesium-containing montmorillonite was prepared. The mixture was then immersed in a support and assembled into a full cell with lithium metal anode and cathode. After standing for a period of time, a polymerized dioxolane composite polymer solid electrolyte was prepared by in-situ polymerization.

2. The method for preparing the in-situ polymerized dioxolane composite solid electrolyte as described in claim 1, characterized in that, The support is selected from at least one of PP membrane, PE membrane, PVDF membrane, PAN membrane, LATP electrospinning matrix, LLZO electrospinning matrix, and BTO electrospinning matrix.

3. The method for preparing the in-situ polymerized dioxolane composite polymer solid electrolyte as described in claim 1 or 2, characterized in that, The lithium salt is selected from at least one of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethyl)sulfonyl)imide, lithium difluorooxalateborate, and lithium hexafluorophosphate.

4. A method for constructing a magnesium fluoride-rich inorganic interface layer, characterized in that, include: A mixture of 1,3-dioxolane, 1-4M lithium salt, and 2-15 wt.% magnesium-containing montmorillonite was uniformly mixed to obtain a mixed solution. The mixed solution was then immersed in a support and assembled into a full cell with lithium metal anode and cathode. After standing for a period of time, a polymerized dioxolane composite polymer solid electrolyte was prepared by in-situ polymerization. Electrochemical cycling was carried out, and magnesium ions and lithium salt anions reacted at the interface of the anode and cathode to form an inorganic component-rich interface layer containing magnesium fluoride.

5. An in-situ polymerized dioxolane composite solid electrolyte, characterized in that, It was prepared using the preparation method of the in-situ polymerized dioxolane composite polymer solid electrolyte as described in claim 1.

6. A magnesium fluoride-containing inorganic interface layer, characterized in that, It was prepared using the method for constructing a magnesium fluoride-rich inorganic interface layer as described in claim 4.

7. A method for manufacturing a battery, characterized in that, include: A mixture of 1,3-dioxolane, 1-4M lithium salt, and 2-15 wt.% magnesium-containing montmorillonite was uniformly mixed to obtain a solution. The solution was then immersed in a support and assembled into a full cell with lithium metal anodes and cathodes. After standing for a period of time, a polymerized dioxolane composite polymer solid electrolyte was prepared by in-situ polymerization. Electrochemical cycling was then performed, and magnesium ions and lithium salt anions reacted at the interface between the cathode and anode to form an inorganic component-rich interface layer containing magnesium fluoride. The battery was thus obtained.

8. A battery, characterized in that, It was prepared using the battery preparation method as described in claim 7.

9. A battery, characterized in that, It includes the in-situ polymerized dioxolane composite polymer solid electrolyte as described in claim 5, or the magnesium fluoride-containing inorganic interface layer as described in claim 6.

10. A battery, characterized in that, The invention includes a lithium metal anode, a cathode, and a polymeric dioxolane composite solid electrolyte formed on a support. The polymeric dioxolane composite solid electrolyte is formed by in-situ polymerization of 1,3-dioxolane monomer and lithium salt under magnesium ion initiation in magnesium-containing montmorillonite. Furthermore, an inorganic component-rich interface layer containing magnesium fluoride is formed at the contact interface between the lithium metal anode and / or cathode and the polymeric dioxolane composite solid electrolyte.

11. The battery as claimed in claim 10, characterized in that, The cathode is a high-nickel cathode.

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