Multifunctional composite ceramic nanowires, solid state electrolytes, batteries, and methods of making the same

Abstract

A multifunctional composite ceramic nanowire, a solid-state electrolyte, a battery and a preparation method thereof, the multifunctional composite ceramic nanowire comprising a one-dimensional continuous structure of a functional ceramic and a zero-dimensional granular functional ceramic uniformly distributed thereon, the functional ceramic being a one-dimensional Li 0.33 La 0.56 TiO 3‑x (LLTO) nanowire, and the zero-dimensional granular functional ceramic being gadolinium-doped cerium oxide Gd 0.1 Ce 0.9 O 1.9 (GDC). The electrochemical performance of a composite solid-state electrolyte using the composite ceramic nanowire as a filler and the compatibility with electrodes are both significantly improved. The cycle performance and rate performance of a solid-state battery using the solid-state electrolyte are obviously improved, and the stability between a polymer matrix electrolyte and positive and negative electrodes is obviously improved.

Description

Technical Field

[0001] This invention relates to solid-state battery technology, and in particular to a multifunctional composite ceramic nanowire, a solid electrolyte, a battery, and a method for preparing the same. Background Technology

[0002] With the advancement of portable electronic devices and the popularization of new energy vehicles, energy storage systems with high safety and high energy density have received widespread attention. Solid-state lithium metal batteries, compared to traditional lithium-ion batteries, replace the flammable and volatile electrolyte components of lithium-ion batteries with a safer solid electrolyte. Furthermore, solid-state electrolytes have better compatibility with lithium metal than liquid electrolytes; therefore, their negative electrode can use lithium metal with extremely high specific capacity (3860 mA hg). -1 Taking both of the above into account, solid-state lithium metal batteries are a type of energy storage that combines high safety with high energy density.

[0003] As a key component of solid-state lithium metal batteries, solid-state electrolytes mainly come in two forms: inorganic solid-state electrolytes and polymer-based solid-state electrolytes. Compared to ceramic electrolytes, polymer-based solid-state electrolytes have better processability, better contact between the positive and negative electrodes, and relatively lower cost, leading to their widespread research. However, polymer solid-state electrolytes suffer from drawbacks such as low room-temperature ionic conductivity, low lithium-ion transference number, poor electrolyte-to-aft electrode interface stability, and poor mechanical properties, which significantly limit the performance of polymer-based solid-state batteries at high rates at room temperature. Therefore, achieving good compatibility at the electrolyte / electrode interface and improving the free lithium content within the polymer solid-state electrolyte are crucial aspects of solid-state battery development. + The concentration and ion transport efficiency are key to achieving excellent rate performance and cycle performance of solid-state lithium metal batteries.

[0004] PVDF, as a common polymer solid electrolyte matrix, contains Li + The transmission mechanism is: [Li(DMF)] x ] + Transport and movement occur within and between PVDF molecular chains. However, the room-temperature ionic conductivity of PVDF electrolytes (~2×10⁻⁶) is limited. -4 S cm -1 The lithium-ion transference number (~0.2) and lithium salt dissociation are both low, and the residual DMF molecules in the electrolyte have poor interfacial compatibility with the positive and negative electrodes; all of these greatly limit the cycle and rate performance of solid-state batteries using PVDF electrolytes.

[0005] 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

[0006] The main objective of this invention is to overcome the deficiencies of the aforementioned background technology and provide a solution.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A multifunctional composite ceramic nanowire comprises a one-dimensional continuous functional ceramic structure and zero-dimensional particulate functional ceramic uniformly distributed thereon, wherein the functional ceramic is a one-dimensional Li. 0.33 La 0.56 TiO 3-x (LLTO) nanowires, the zero-dimensional particulate functional ceramic being gadolinium-doped cerium oxide (Gd) 0.1 Ce 0.9 O 1.9 (GDC).

[0009] A method for preparing the aforementioned multifunctional composite ceramic nanowires includes the following steps:

[0010] Gd 0.1 Ce 0.9 O 1.9 (GDC) particles are uniformly dispersed in the material used to prepare Li 0.33 La 0.56 TiO 3-x A mixture was obtained by electrospinning a solution of (LLTO) nanowire precursors, and then the composite ceramic nanowire precursor was prepared using the mixture. After calcination, GDC@LLTO composite ceramic nanowires were obtained.

[0011] Furthermore, the method specifically includes the following steps:

[0012] LiNO3 and La(NO3)3·6H2O were dissolved in a mixed solution of DMF and acetic acid; then, an appropriate amount of GDC nanoparticles were added and dispersed evenly; then, PVP was added to adjust the solution viscosity, and tetrabutyl titanate was added, and the mixture was stirred thoroughly to obtain the electrospinning solution.

[0013] GDC@LLTO nanowire precursors were prepared by electrospinning using the electrospinning solution.

[0014] The GDC@LLTO nanowire precursor was calcined at 750–900°C and then naturally cooled to obtain the GDC@LLTO composite ceramic nanowire.

[0015] A composite solid electrolyte includes a lithium salt, a polymer matrix, and a filler, wherein the filler includes one of GDC particles, LLTO nanowires, and GDC@LLTO composite ceramic nanowires.

[0016] Furthermore, the polymer matrix is ​​PVDF.

[0017] Furthermore, the lithium salt is LiFSI.

[0018] A method for preparing the composite solid electrolyte includes the following steps:

[0019] Dissolve the lithium salt in a DMF solution;

[0020] The filler comprising GDC@LLTO composite ceramic nanowires was added to the solution and dispersed evenly.

[0021] Then add the polymer matrix powder and stir until homogeneous;

[0022] The solution is then poured into a container and dried.

[0023] A lithium metal battery having the aforementioned composite solid electrolyte.

[0024] The present invention has the following beneficial effects:

[0025] This invention provides a multifunctional composite ceramic nanowire, comprising a functional ceramic Li with a one-dimensional continuous structure. 0.33 La 0.56 TiO 3-x (LLTO) nanowires and zero-dimensional particulate functional ceramic Gd uniformly distributed thereon 0.1 Ce 0.9 O 1.9 (GDC), as a filler, can be used to construct continuous Li-type electrolytes in polymer-based electrolytes, especially PVDF-based electrolytes. + The invention improves ion transport efficiency by creating a transport channel; simultaneously, it enhances the degree of lithium salt dissociation and lithium-ion transference number in the electrolyte, resulting in uniform lithium deposition and extended battery cycle life. When the multifunctional composite ceramic nanowires of this invention are added as fillers to polymer-based electrolytes, especially PVDF-based electrolytes, the room-temperature ionic conductivity, lithium-ion transference number, and electrochemical window of the resulting composite solid-state electrolyte are significantly improved. The cycle stability of Li / Li symmetric batteries prepared using this composite solid-state electrolyte is significantly enhanced; the NCM811 / Li solid-state battery exhibits excellent cycle and rate performance. This invention has broad application prospects in the field of solid-state lithium metal batteries.

[0026] In a preferred embodiment, multifunctional composite ceramic nanowires are used as fillers for the solid electrolyte. One-dimensional LLTO nanowires construct continuous lithium-ion transport channels within the PVDF polymer solid electrolyte, while zero-dimensional GDC particles are grown on the surface of the LLTO one-dimensional nanowires. GDC, as a type of oxygen-vacancy-rich ceramic, possesses positively charged oxygen vacancies, which can effectively immobilize lithium salt anions, increase lithium-ion transference number, and promote lithium salt dissociation. The electrochemical performance and electrode compatibility of the composite solid electrolyte using GDC@LLTO composite ceramic nanowires as fillers are significantly improved, which is of great significance for enhancing the electrochemical performance of PVDF-based electrolytes.

[0027] The solid-state electrolyte provided by this invention can be well matched with lithium metal anodes and NCM811 cathodes. The addition of GDC@LLTO composite ceramic nanowires to the solid-state electrolyte significantly improves the cycle performance and rate performance of solid-state batteries using this electrolyte. Simultaneously, it significantly improves the stability between polymer-based electrolytes, especially PVDF electrolytes, and the cathodes and anodes. Therefore, this invention is of great significance for achieving long-term room-temperature cycling of lithium metal batteries and has high application value. Attached Figure Description

[0028] Figure 1 In this paper, 'a' is a SEM image of the LLTO nanowires prepared in Example 1 of this invention; Figure 1 In the image, b represents a high-magnification SEM image of the LLTO nanowires prepared in Example 1, along with mapping images of O, Ti, and La elements.

[0029] Figure 2 The image shows the XRD pattern of the LLTO nanowires prepared in Example 1.

[0030] Figure 3 The XRD patterns of GDC@LLTO composite ceramic nanowires prepared at different calcination temperatures in Example 2 are shown.

[0031] Figure 4 In Example 2, 'a' is a SEM image of the composite ceramic nanowire with a GDC to LLTO mass ratio of 5:95. Figure 4 b in Example 2 is a SEM image of the composite ceramic nanowire with a GDC to LLTO mass ratio of 10:90. Figure 4 c in Example 2 is a SEM image of the composite ceramic nanowire with a GDC to LLTO mass ratio of 15:85. Figure 4 In the image, d represents the SEM image of the composite ceramic nanowire with a GDC to LLTO mass ratio of 20:80 in Example 2.

[0032] Figure 5 In the image, 'a' is an optical photograph of the PVDF solid electrolyte membrane prepared in Example 3. Figure 5In the image, b is a scanned image of the PVDF solid electrolyte membrane prepared in Example 3.

[0033] Figure 6 In the image, 'a' is an optical photograph of the PVLG solid electrolyte membrane prepared in Example 4. Figure 6 In the image, b is a scanned image of the PVLG solid electrolyte membrane prepared in Example 4.

[0034] Figure 7 Electrochemical performance of the NCM811 / PVDF / Li, NCM811 / PVG / Li, NCM811 / PVL / Li and NCM811 / PVLG / Li solid-state batteries assembled for Example 7. Detailed Implementation

[0035] The embodiments of the present invention will be described in detail below. It should be emphasized that the following description is merely exemplary and is not intended to limit the scope and application of the present invention.

[0036] In some embodiments, the present invention provides a multifunctional composite ceramic nanowire comprising a one-dimensional continuous functional ceramic structure and a zero-dimensional particulate functional ceramic uniformly distributed thereon. The functional ceramic is a one-dimensional Li. 0.33 La 0.56 TiO 3-x (LLTO) nanowires are a type of material used to construct ion transport channels in polymer electrolytes, exhibiting high room-temperature ionic conductivity (~10). -3 S cm -1 This LLTO nanowire can construct highly efficient ion transport channels in polymer solid electrolytes. The zero-dimensional particulate functional ceramic is gadolinium-doped cerium oxide (Gd). 0.1 Ce 0.9 O 1.9 GDC (Glass Dioxide) is a material that promotes the dissociation of lithium salts in polymer electrolytes. As a type of oxygen-vacancy-rich ceramic, it can effectively fix the anions of lithium salts used in lithium batteries, increase the lithium-ion transference number, and promote lithium salt dissociation. This invention refers to this multifunctional composite ceramic nanowire as GDC@LLTO composite ceramic nanowire. Utilizing it as a filler significantly improves the electrochemical performance of composite solid electrolytes and its performance in solid-state batteries.

[0037] For example, the microstructure of the multifunctional composite ceramic nanowire is as follows: Figure 4As shown in (b), zero-dimensional particles are grown on the surface of one-dimensional nanowires in the composite ceramic, exhibiting a rough microstructure and good continuity with a nanowire diameter of approximately 200 nm. When this particle is added as a filler to polyvinylidene fluoride (PVDF) substrate, the room-temperature ionic conductivity, lithium-ion transference number, and electrochemical window of the resulting composite solid electrolyte are significantly improved. The cycling stability of the Li / Li symmetric battery prepared using this material is significantly enhanced; the NCM811 / Li solid-state battery demonstrates excellent cycling and rate performance. This invention has broad application prospects in the field of solid-state lithium metal batteries.

[0038] In some embodiments, the present invention provides a method for preparing multifunctional composite ceramic nanowires, comprising the following steps:

[0039] Gd 0.1 Ce 0.9 O 1.9 (GDC) particles are uniformly dispersed in the material used to prepare Li 0.33 La 0.56 TiO 3-x A mixture was obtained by electrospinning a solution of (LLTO) nanowire precursors. This mixture was then used to prepare composite ceramic nanowire precursors. Finally, multifunctional composite ceramic nanowires were prepared by calcination in a muffle furnace at a suitable temperature. The resulting product was Gd... 0.1 Ce 0.9 O 1.9 (GDC) nanoparticles are distributed in Li 0.33 La 0.56 TiO 3-x GDC@LLTO composite ceramic nanowires on (LLTO) nanowires.

[0040] In a preferred embodiment, the preparation method of the multifunctional composite ceramic nanowire specifically includes the following steps:

[0041] S1: Dissolve appropriate amounts of LiNO3 and La(NO3)3·6H2O in a mixed solution of DMF (N,N-dimethylformamide) and acetic acid; then, add appropriate amounts of GDC nanoparticles and ultrasonically disperse them evenly; then, add polyvinylpyrrolidone (PVP) to adjust the solution viscosity; finally, add tetrabutyl titanate and stir thoroughly to form a light yellow uniform slurry, which is the electrospinning solution.

[0042] S2: Using the above electrospinning solution, the electrospinning voltage is -1 to 20 kV, and the liquid propulsion rate is 1 mL / h. -1 The distance between the needle and the receiving roller was 15 cm, the temperature was 34 °C, and the ambient humidity was 55%. GDC@LLTO nanowire precursors were prepared by electrospinning under these parameters.

[0043] S3: Place the GDC@LLTO nanowire precursor in an alumina ceramic boat and incubate at 1℃ for 1 minute. -1 The temperature was increased from room temperature to 280°C and held for 2 hours; thereafter, the temperature was increased at a rate of 5°C per minute. -1 The heating rate was increased from 280℃ to 900℃ and held for 3 hours; finally, it was naturally cooled to room temperature to obtain GDC@LLTO nanowires.

[0044] This invention successfully prepared GDC@LLTO composite ceramic nanowires using a fast lithium-ion conductor ceramic LLTO precursor and GDC nanopowder. LLTO possesses high room-temperature ionic conductivity, enabling it to construct continuous lithium-ion transport channels in PVDF polymer solid electrolytes. GDC, as an oxygen-vacancy-rich ceramic, effectively immobilizes lithium salt anions due to the positive charge of oxygen vacancies, thereby increasing lithium-ion transference number and promoting lithium salt dissociation. The electrochemical performance and electrode compatibility of the composite solid electrolyte using GDC@LLTO composite ceramic nanowires as fillers are significantly improved, which is of great significance for enhancing the electrochemical performance of polymer-based electrolytes such as PVDF-based electrolytes in solid-state batteries.

[0045] Therefore, embodiments of the present invention also provide a composite solid electrolyte, which includes a lithium salt, a polymer matrix and a filler, wherein the filler includes GDC@LLTO composite ceramic nanowires.

[0046] In some embodiments, the polymer matrix of the composite solid electrolyte is PVDF (polyvinylidene fluoride), and the lithium salt is LiFSI (lithium bisfluorosulfonyl imide). The electrolyte can be prepared by casting followed by a drying process.

[0047] The composite solid electrolyte provided by this invention can be well matched with lithium metal anode and NCM811 cathode. The addition of GDC@LLTO composite ceramic nanowires to the solid electrolyte significantly improves the cycle performance and rate performance of solid batteries using this solid electrolyte, making it highly valuable for application.

[0048] This invention also provides a lithium metal battery having the aforementioned composite solid electrolyte.

[0049] This invention also provides another composite solid electrolyte, which includes a lithium salt, a polymer matrix and a filler, wherein the filler includes LLTO nanowires or GDC particles.

[0050] In a preferred embodiment, the fabrication process of the LLTO nanowire includes the following steps:

[0051] S1: Dissolve appropriate amounts of LiNO3 (lithium nitrate) and La(NO3)3·6H2O (lanthanum nitrate hexahydrate) in a mixed solution of DMF (N,N-dimethylformamide) and acetic acid; then, add polyvinylpyrrolidone (PVP) to make the solution reach a suitable viscosity; finally, add tetrabutyl titanate and stir thoroughly to obtain the electrospinning solution.

[0052] S2: Using the above electrospinning solution, the electrospinning voltage is -1 to 20 kV, and the liquid propulsion rate is 1 mL / h. -1 The distance between the needle and the receiving roller was 15 cm, the temperature was 34 °C, and the ambient humidity was 55%. LLTO nanowire precursors were prepared by electrospinning under these parameters.

[0053] S3: Place the LLTO nanowire precursor in an alumina ceramic boat and incubate at 1℃ for 1 minute. -1 The temperature was increased from room temperature to 280°C and held for 2 hours; thereafter, the temperature was increased at a rate of 5°C per minute. -1 The heating rate was increased from 280℃ to 900℃ and held for 3 hours; finally, it was naturally cooled to room temperature to obtain LLTO nanowires.

[0054] The present invention also provides a lithium metal battery having a composite solid electrolyte including the LLTO nanowires.

[0055] Example 1

[0056] This embodiment provides a method for preparing LLTO nanowires:

[0057] LLTO ceramic nanowires were prepared using the sol-gel method, and the specific preparation steps are as follows:

[0058] S1: Dissolve 0.1311g LiNO3 and 1.19g La(NO3)3·6H2O in a mixed solution of 7.5mL DMF and 1.5mL acetic acid;

[0059] S2: Add 0.6g PVP to the solution of S1 and stir for 3 hours;

[0060] S3: Add 1.7g of tetrabutyl titanate to the solution containing S2 and stir for 12 hours to prepare a pale yellow, clear, and transparent solution;

[0061] S4: Electrospinning voltage -1 to 20kV, driving rate 1mL / h -1 The distance between the needle and the receiving roller was 15 cm, the electrospinning temperature was 34℃, and the ambient humidity was 55%. LLTO precursor slurry was electrospun under the above parameters to prepare LLTO nanowire precursors.

[0062] S5: Place the LLTO nanowire precursor in an alumina ceramic boat and incubate at 1℃ for 1 minute.-1 The heating rate was increased from room temperature to 280℃, and the temperature was maintained for 2 hours;

[0063] S6: at 5℃ min -1 The heating rate was increased from 280℃ to 900℃ and held for 3 hours; finally, it was naturally cooled to room temperature to obtain LLTO nanowires.

[0064] Experimental results are as follows Figure 1 As shown in a-b, SEM images of LLTO nanowires show that the nanowires have a diameter of approximately 500 nm; high-magnification SEM images of LLTO nanowires reveal a porous surface. Energy-dispersive X-ray spectroscopy (EDS) results of LLTO nanowires indicate that O, Ti, and La elements are uniformly distributed within the nanowires. Figure 2 The X-ray diffraction (XRD) pattern of the LLTO nanowires shown matches well with PDF#45-0465 and has a tetragonal phase structure, indicating that the prepared LLTO nanowires are pure phase.

[0065] Example 2

[0066] This example provides a method for preparing GDC@LLTO composite ceramic nanowires:

[0067] S1: Dissolve an appropriate amount of 0.05g LiNO3 and 0.396g La(NO3)3·6H2O in a mixed solution of 2.5mL DMF and 0.5mL acetic acid;

[0068] S2: Add an appropriate amount of GDC nanopowder to the solution of S1 and disperse it evenly by ultrasonication;

[0069] S3: Add 0.6g PVP to S2 to adjust the solution viscosity;

[0070] S4: Add 0.567g of tetrabutyl titanate to S3 and stir thoroughly to prepare a light yellow uniform slurry;

[0071] S5: Using the above electrospinning solution, the electrospinning voltage is -1 to 20 kV, and the liquid propulsion rate is 1 mL / h. -1 The distance between the needle and the receiving roller was 15 cm, the temperature was 34 °C, and the ambient humidity was 55%. GDC@LLTO nanowire precursors were prepared by electrospinning under these parameters.

[0072] S6: Place the GDC@LLTO nanowire precursor in an alumina ceramic boat and incubate at 1℃ for 1 minute. -1 The heating rate was increased from room temperature to 280℃, and the temperature was maintained for 2 hours;

[0073] S7: at 5℃ min -1The heating rate was increased from 280℃ to a certain calcination temperature, and the temperature was maintained at this temperature for 3 hours. Finally, the temperature was naturally cooled to room temperature to obtain GDC@LLTO nanowires.

[0074] In this example, we first explored the effect of different calcination temperatures on the phase composition of GDC@LLTO nanowires. With a GDC content of 10 wt% in the composite nanowires, the XRD patterns of the GDC@LLTO nanowires calcined at 750, 800, 850, and 900 °C are shown below. Figure 3 As shown, at calcination temperatures of 750, 800, and 850 °C, distinct impurity peaks appeared at positions 26.3 and 27.1 °C, corresponding to Li₂TiO₃ (PDF#33-0381) and La₂Ti₂O₇ (PDF#70-1690), respectively. When the calcination temperature was 900 °C, the impurity peaks disappeared, and the GDC@LLTO composite ceramic nanowires were found to be a pure phase.

[0075] Meanwhile, the effect of GDC content on the morphology of composite nanowires was investigated. Figure 4 SEM images of composite ceramic nanowires with different GDC to LLTO mass ratios are shown. When the GDC to LLTO mass ratio is 5:95, the surface of the composite ceramic nanowires is relatively smooth, with a diameter of approximately 170 nm and uniform morphology. When the mass ratio is 10:90, the surface of the composite nanowires has small particles growing on it, resulting in a rough and uneven surface. The nanowires have a diameter of approximately 200 nm and good continuity. However, when the mass ratio is 15:85, the nanowires appear as ribbons with uneven diameters and exhibit breakage. Further increasing the proportion of GDC to a mass ratio of 20:80 results in nanowires with a surface composed of many fine particles, reaching a diameter of approximately 1 μm. Considering both phase composition and microstructure, the preferred composition ratio for the nanowires is determined to be a GDC to LLTO mass ratio of 1:9, with a calcination temperature of 900℃.

[0076] Example 3

[0077] This example provides a method for preparing a PVDF polymer solid electrolyte:

[0078] S1: Dissolve 0.276g LiFSI completely in 15mL of DMF solution;

[0079] S2: Add 0.4g PVDF powder (Mw=300,000) to S2 and stir for 6 hours;

[0080] S3: Pour the solution in S3 into a glass dish with a diameter of 10cm;

[0081] S4: Dry in a 55℃ forced-air oven for 24 hours to obtain a light yellow solid electrolyte, which is then cut into 19mm diameter discs for use.

[0082] Figure 5 Image a shows an optical image of the PVDF electrolyte, which appears white with a smooth surface. The SEM image of the PVDF electrolyte reveals obvious PVDF spherulites and a porous surface. Figure 5 b). The PVDF electrolyte prepared using this method has a room temperature ionic conductivity of 3.69 × 10⁻⁶. -4 S cm -1 The lithium-ion transference number is 0.24, the oxidation resistance window is 4.1V, and the activation energy for lithium-ion migration is 0.31eV.

[0083] Example 4

[0084] This example provides a method for preparing a PVDF-based composite solid electrolyte (PVLG):

[0085] S1: Dissolve 0.276g LiFSI completely in 15mL of DMF solution;

[0086] S2: Add 60 mg of GDC@LLTO nanowires to S1 and disperse them evenly by ultrasonication;

[0087] S3: Add 0.4g PVDF powder (Mw=300,000) to S2 and stir for 6 hours;

[0088] S4: Pour the solution from S3 into a glass dish with a diameter of 10cm;

[0089] S5: Dry in a 55℃ forced-air oven for 24 hours to obtain a light yellow solid electrolyte, which is then cut into 19mm diameter discs for use.

[0090] like Figure 6 As shown in a–b, the PVLG electrolyte is pale yellow, and the GDC@LLTO nanowires are distributed within the voids of the PVDF solid electrolyte, exhibiting a relatively dense surface. The PVLG electrolyte prepared using this method has a room-temperature ionic conductivity of 8.71 × 10⁻⁶. -4 Scm -1 The lithium-ion transference number is 0.66, the oxidation resistance window is 4.5V, and the activation energy for lithium-ion migration is 0.24eV.

[0091] Example 5

[0092] This example provides a method for preparing a PVDF-based composite solid electrolyte (PVG):

[0093] S1: Dissolve 0.276g LiFSI completely in 15mL of DMF solution;

[0094] S2: Add 60mg of GDC nanoparticles to S1 and disperse them evenly by ultrasonication;

[0095] S3: Add 0.4g PVDF powder (Mw=300,000) to S2 and stir for 6 hours;

[0096] S4: Pour the solution from S3 into a glass dish with a diameter of 10cm;

[0097] S5: Dry in a 55℃ forced-air oven for 24 hours to obtain a light yellow solid electrolyte, which is then cut into 19mm diameter discs for use.

[0098] The PVG electrolyte prepared using this method has a room temperature ionic conductivity of 3.61 × 10⁻⁶. -4 S cm -1 The lithium-ion transference number is 0.51, and the activation energy for lithium-ion migration is 0.28 eV.

[0099] Example 6

[0100] This example provides a method for preparing a PVDF-based composite solid electrolyte (PVL):

[0101] S1: Dissolve 0.276g LiFSI completely in 15mL of DMF solution;

[0102] S2: Add 60 mg of LLTO nanowires to S1 and disperse them evenly by ultrasonication;

[0103] S3: Add 0.4g PVDF powder (Mw=300,000) to S2 and stir for 6 hours;

[0104] S4: Pour the solution from S3 into a glass dish with a diameter of 10cm;

[0105] S5: Dry in a 55℃ forced-air oven for 24 hours to obtain a light yellow solid electrolyte, which is then cut into 19mm diameter discs for use.

[0106] The PVL electrolyte prepared using this method has a room temperature ionic conductivity of 4.37 × 10⁻⁶. -4 S cm -1 The lithium-ion transference number is 0.38, and the activation energy for lithium-ion migration is 0.29 eV.

[0107] Example 7

[0108] This example provides a method for preparing a solid-state battery using a PVDF-based solid-state electrolyte:

[0109] S1: The positive electrode active material NCM811, the conductive agent Super P and the binder PVDF 5130 are dispersed in N-methyl-2-pyrrolidone (NMP) at a mass ratio of 8:1:1 to prepare a uniform slurry;

[0110] S2: Apply the slurry evenly onto the aluminum foil; then place it in a vacuum oven at 120°C and dry for 3 hours;

[0111] S3: Used by stamping into 12mm round discs with a positive electrode active material loading of 1.4mg / cm³. -2 ;

[0112] S4: Using the positive electrode from S3, the negative electrode uses lithium metal with a diameter of 15 mm, and the electrolytes are PVDF, PVLG, PVG and PVL electrolytes prepared in Examples 3 to 6, respectively. CR2032 coin cells are prepared in an argon glove box.

[0113] Cycle performance tests were performed on the NCM811 / PVDF / Li, NCM811 / PVG / Li, NCM811 / PVL / Li, and NCM811 / PVLG / Li solid-state batteries assembled in this example. Figure 7 At a charge / discharge rate of 2C, the solid-state battery using the PVLG electrolyte in Example 4 can operate stably for 1500 cycles, while solid-state batteries assembled with other types of electrolytes all exhibited significant capacity decay. This indicates that the GDC@LLTO composite ceramic nanowires significantly improve the electrochemical performance of the PVDF electrolyte; simultaneously, they significantly improve the stability between the PVDF electrolyte and the positive and negative electrodes. The test results demonstrate that this invention is of great significance for achieving long-term cycling at room temperature in lithium metal batteries.

[0114] The background section of this invention may include background information about the problems or environment in which the invention is being developed, and is not necessarily a description of prior art. Therefore, the content included in the background section does not constitute an admission of prior art by the applicant.

[0115] 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 composite solid electrolyte, characterized in that, The product comprises a lithium salt, a polymer matrix, and a filler, wherein the filler includes GDC@LLTO composite ceramic nanowires. The GDC@LLTO composite ceramic nanowires comprise a one-dimensional continuous functional ceramic structure and zero-dimensional particulate functional ceramics uniformly distributed thereon. The functional ceramic is a one-dimensional Li₂O₃. 0.33 La 0.56 TiO 3−x (LLTO) nanowires, wherein the zero-dimensional particulate functional ceramic is gadolinium-doped cerium oxide (Gd). 0.1 Ce 0.9 O 1.9 (GDC).

2. The composite solid electrolyte as described in claim 1, characterized in that, The polymer matrix is ​​PVDF.

3. The composite solid electrolyte as described in claim 1 or 2, characterized in that, The lithium salt is LiFSI.

4. A method for preparing the composite solid electrolyte as described in any one of claims 1 to 3, characterized in that, It also includes the following steps: Dissolve the lithium salt in a DMF solution; The filler comprising GDC@LLTO composite ceramic nanowires was added to the solution and dispersed evenly. Then add the polymer matrix powder and stir until homogeneous; The solution is then poured into a container and dried.

5. The method as described in claim 4, characterized in that, The process also includes the following steps for preparing the GDC@LLTO composite ceramic nanowires: [The text abruptly ends here, likely due to an incomplete sentence or missing information.] 0.1 Ce 0.9 O 1.9 (GDC) particles are uniformly dispersed in the substrate used to prepare Li 0.33 La 0.56 TiO 3−x A mixture was obtained in the precursor solution of (LLTO) nanowires, and then the composite ceramic nanowire precursor was prepared by electrospinning using the mixture. After calcination, GDC@LLTO composite ceramic nanowires were prepared.

6. The method as described in claim 5, characterized in that, The preparation of the GDC@LLTO composite ceramic nanowires specifically includes the following steps: LiNO3 and La(NO3)3·6H2O were dissolved in a mixed solution of DMF and acetic acid; then, an appropriate amount of GDC nanoparticles were added and dispersed evenly; then, PVP was added to adjust the solution viscosity, and tetrabutyl titanate was added, and the mixture was stirred thoroughly to obtain the electrospinning solution. GDC@LLTO nanowire precursors were prepared by electrospinning using the electrospinning solution. The GDC@LLTO nanowire precursor was calcined at 750~900℃ to prepare the GDC@LLTO composite ceramic nanowire.

7. A lithium metal battery, characterized in that, It has a composite solid electrolyte as described in any one of claims 1 to 3.

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