A preparation method of a functional lanthanum hydroxide composite PEO-based solid electrolyte for a solid-state battery

Abstract

The application discloses a preparation method of a functional lanthanum hydroxide composite PEO-based solid electrolyte for a solid-state battery, and relates to a preparation method of a PEO-based solid electrolyte.The application solves the problems of poor contact with an electrode plate, low ion transmission and unstable interface of an existing PEO electrolyte.The preparation method comprises the following steps: one, preparation of functional group modified La(OH)3-NH2 nanofibers; and two, preparation of a PEO-based composite solid electrolyte.The application is used for the preparation of the functional lanthanum hydroxide composite PEO-based solid electrolyte for the solid-state battery.

Description

Technical Field

[0001] This invention relates to a method for preparing a PEO-based solid electrolyte. Background Technology

[0002] Lithium-ion batteries have garnered significant market attention due to their high energy density, long cycle life, and high charge / discharge rate, and have become the most widely used electrochemical energy storage technology. Traditional lithium-ion batteries use liquid electrolytes, which pose risks of leakage, flammability, and even explosion. Solid-state batteries, with their solid electrolytes, can replace the liquid electrolytes and separators in traditional lithium-ion batteries, improving battery safety. The development of lithium-ion battery electrolytes towards solid-state and high thermal stability further enhances battery safety, potentially addressing battery safety issues at their source.

[0003] In solid polymer electrolytes, the ether-based repeating units of PEO solid polymer electrolytes exhibit good lithium-ion transport capacity and good compatibility with metallic lithium. However, existing PEO electrolytes still suffer from poor contact with the electrode, low ion transport, and interfacial instability, which are problems that need to be addressed in solid-state batteries. Summary of the Invention

[0004] This invention aims to address the problems of poor contact with the electrode and low ion transport in existing PEO electrolytes, and thus provides a method for preparing a functional lanthanum hydroxide composite PEO-based solid electrolyte for solid-state batteries.

[0005] A method for preparing a functional lanthanum hydroxide composite PEO-based solid electrolyte for solid-state batteries, comprising the following steps: I. Preparation of La(OH)3-NH2 nanofibers modified with functional groups: ① Mix La(NO3)3·6H2O with deionized water to obtain a La(NO3)3 solution; ② Mix sodium hydroxide and potassium hydroxide to obtain a NaOH / KOH mixture; ③ Mix the La(NO3)3 solution with the NaOH / KOH mixture until homogeneous and preheat to a warm temperature. Then shake well and heat to react. Finally cool to room temperature to obtain the reaction product. ④ The reaction product was filtered and centrifuged and washed to obtain La(OH)3 nanofibers; ⑤ Dissolve La(OH)3 nanofibers in ethanol to obtain La(OH)3 solution, add APTES dropwise to the La(OH)3 solution to react, and finally filter, wash and dry to obtain La(OH)3-NH2 two-dimensional fiber filler; II. Preparation of PEO-based composite solid electrolytes: ① Add the La(OH)3-NH2 two-dimensional fiber filler to acetonitrile and mix evenly to obtain a La(OH)3-NH2 solution. Then dissolve LiTFSI and PEO in the La(OH)3-NH2 solution and stir evenly to obtain a homogeneous solution. ② Pour the uniform solution onto a polytetrafluoroethylene plate, then vacuum dry and allow it to stand at room temperature to complete the preparation method of functional lanthanum hydroxide composite PEO-based solid electrolyte for solid-state batteries.

[0006] The beneficial effects of this invention are: 1. The La(OH)3 nanofibers modified with the electron-donating group –NH2 prepared in this invention, when added as a filler to a PEO-based electrolyte, effectively inhibit the crystallization of the polymer matrix, increase the proportion of amorphous PEO molecules at the filler / PEO interface, and the high mobility of their chain segments can provide efficient Li... + On the one hand, the packing effectively suppressed TFSI by mitigating the transport pathway. - The migration motion of these molecules greatly enhances the ion mobility in PEO-based solid electrolytes. Furthermore, it lowers the melting point of the solid electrolyte to below 50°C, significantly increasing the disorder of the solid electrolyte under 60°C battery operating conditions and improving the problem of poor electrode contact, thus facilitating lithium ion migration.

[0007] 2. Functional La(OH)3–NH2 nanofibers were prepared using a traditional and simple method. On the one hand, the oxygen vacancies on the surface of La(OH)3–NH2 nanofibers can capture TFSI in LiTFSI. - Anions, therefore can increase Li + The degree of freedom of movement promotes Li + Rapid migration of cations at the solid / solid interface; on the other hand, the introduction of functional electron-donating groups limits TFSI. - The movement of these molecules significantly increases the migration rate of lithium ions. At 60℃, the ionic conductivity of the La(OH)3–NH2 system can reach 9.6 × 10⁻⁶. -4 Compared to the blank electrolyte, the ionic conductivity (S / cm) is significantly improved. The lithium-ion transference number can be increased from 0.20 to 0.51.

[0008] 3. The PEO-based solid electrolyte constructed from multifunctional La(OH)3 nanofiber filler enables lithium metal batteries based on LiFePO4 (LFP) cathodes to exhibit excellent cycling performance at high rates. After 350 cycles at 6C, the capacity retention rate is 64.4%, and after 600 cycles at 12C, the capacity retention rate is 63.4%.

[0009] In summary, the product proposed in this invention has good application prospects and practical value. The functional lanthanum hydroxide composite PEO-based solid electrolyte for solid-state batteries prepared by this invention is a high-rate solid electrolyte with broad application prospects in high-rate solid-state batteries.

[0010] Instruction manual illustrations Figure 1 The XRD pattern of the La(OH)3 nanofibers prepared in step 4 of Example 1; Figure 2 This is a TEM image of the La(OH)3 nanofibers prepared in step 4 of Example 1; Figure 3 The image shows an HRTEM image of the La(OH)3 nanofibers prepared in step 4 of Example 1. Figure 4 The elemental scattering diagram of the La(OH)3 nanofibers prepared in step 4 of Example 1; Figure 5 EPR image of La(OH)3 nanofibers prepared in step 4 of Example 1; Figure 6 The image shows an infrared spectrum. 1 is the La(OH)3 nanofiber prepared in step 4 of Example 1, and 2 is the La(OH)3-NH2 two-dimensional fiber filler prepared in step 5 of Example 1. Figure 7 The elemental scattering diagram is shown for the La(OH)3-NH2 two-dimensional fiber filler prepared in step 1⑤ of Example 1. Figure 8 The images show the XRD patterns of solid electrolytes. 1 is PEO:LiTFSI prepared in Comparative Experiment 1, and 2 is LNPE-15 prepared in Example 1. Figure 9 The thermogravimetric diagrams are for solid electrolytes. 1 is LNPE-20 prepared in Example 2, 2 is LNPE-15 prepared in Example 1, 3 is LNPE-10 prepared in Example 3, 4 is LNPE-5 prepared in Example 4, and 5 is PEO:LiTFSI prepared in Comparative Experiment 1. Figure 10 A scanning electron microscope image of LNPE-15 prepared in Example 1; Figure 11 The images show LSV images of solid electrolytes at 60℃. 1 is PEO:LiTFSI prepared in Comparative Experiment 1, 2 is LPE-15 prepared in Comparative Experiment 2, and 3 is LNPE-15 prepared in Example 1. Figure 12The data are the rate curves of LFP|Li batteries from 0.2C to 6C at 60℃. 1 is an LFP|Li battery based on LNPE-15 solid electrolyte, 2 is an LFP|Li battery based on LPE-15 solid electrolyte, and 3 is an LFP|Li battery based on PEO:LiTFSI solid electrolyte. Figure 13 The charge-discharge curves of LFP|Li batteries based on LNPE-15 solid electrolyte at 60℃ and 12C are shown. Figure 14 The diagram shows the long-cycle operation of LFP|Li batteries at 60℃ and 12C. 1 is an LFP|Li battery based on LNPE-15 solid electrolyte, 2 is an LFP|Li battery based on LPE-15 solid electrolyte, and 3 is an LFP|Li battery based on PEO:LiTFSI solid electrolyte. Figure 15 The graphs show the long-term cycling of LFP|Li batteries at 60℃ and 6C. 1 is an LFP|Li battery based on LNPE-15 solid electrolyte, 2 is an LFP|Li battery based on LPE-15 solid electrolyte, and 3 is an LFP|Li battery based on PEO:LiTFSI solid electrolyte. Figure 16 EIS curves of LFP|Li batteries at 60℃ are shown. 1 is an LFP|Li battery based on LNPE-15 solid electrolyte, 2 is an LFP|Li battery based on LPE-15 solid electrolyte, and 3 is an LFP|Li battery based on PEO:LiTFSI solid electrolyte. Figure 17 The time-current curves of LFP|Li batteries based on LNPE-15 solid electrolyte at 10mV are shown. Figure 18 The time-current curves of LFP|Li batteries based on PEO:LiTFSI solid electrolyte are shown at 10 mV. Detailed Implementation

[0011] Specific Implementation Method 1: This implementation method provides a method for preparing a functional lanthanum hydroxide composite PEO-based solid electrolyte for solid-state batteries, which is carried out according to the following steps: I. Preparation of La(OH)3-NH2 nanofibers modified with functional groups: ① Mix La(NO3)3·6H2O with deionized water to obtain a La(NO3)3 solution; ② Mix sodium hydroxide and potassium hydroxide to obtain a NaOH / KOH mixture; ③ Mix the La(NO3)3 solution with the NaOH / KOH mixture until homogeneous and preheat to a warm temperature. Then shake well and heat to react. Finally cool to room temperature to obtain the reaction product. ④ The reaction product was filtered and centrifuged and washed to obtain La(OH)3 nanofibers; ⑤ Dissolve La(OH)3 nanofibers in ethanol to obtain La(OH)3 solution, add APTES dropwise to the La(OH)3 solution to react, and finally filter, wash and dry to obtain La(OH)3-NH2 two-dimensional fiber filler; II. Preparation of PEO-based composite solid electrolytes: ① Add the La(OH)3-NH2 two-dimensional fiber filler to acetonitrile and mix evenly to obtain a La(OH)3-NH2 solution. Then dissolve LiTFSI and PEO in the La(OH)3-NH2 solution and stir evenly to obtain a homogeneous solution. ② Pour the uniform solution onto a polytetrafluoroethylene plate, then vacuum dry and allow it to stand at room temperature to complete the preparation method of functional lanthanum hydroxide composite PEO-based solid electrolyte for solid-state batteries.

[0012] In step 2①, LiTFSI is the full name of lithium bis(trifluoromethanesulfonate)imide; and PEO is the full name of polyethylene oxide.

[0013] The method of doping with inorganic fillers in this embodiment significantly reduces the crystallinity of the PEO polymer matrix. One-dimensional (1D) inorganic fillers can significantly improve the crystallinity of Li. + The conductivity of ions is due to their ability to facilitate the transport of ions along continuous ion transport pathways. Fillers with oxygen vacancies and electron-donating groups (amino groups) possess abundant positive charges, which can limit TFSI. - The movement of these molecules greatly increases the lithium-ion transference number.

[0014] The beneficial effects of this embodiment are: 1. The La(OH)3 nanofibers modified with the electron-donating group –NH2 prepared in this embodiment, when added to PEO-based electrolytes as fillers, effectively inhibit the crystallization of the polymer matrix, increase the proportion of amorphous PEO molecules at the filler / PEO interface, and the high mobility of their chain segments can provide efficient Li + On the one hand, the packing effectively suppressed TFSI by mitigating the transport pathway. - The migration motion of these molecules greatly enhances the ion mobility in PEO-based solid electrolytes. Furthermore, it lowers the melting point of the solid electrolyte to below 50°C, significantly increasing the disorder of the solid electrolyte under 60°C battery operating conditions and improving the problem of poor electrode contact, thus facilitating lithium ion migration.

[0015] 2. Functional La(OH)3–NH2 nanofibers were prepared using a traditional and simple method. On the one hand, the oxygen vacancies on the surface of La(OH)3–NH2 nanofibers can capture TFSI in LiTFSI.- Anions, therefore can increase Li + The degree of freedom of movement promotes Li + Rapid migration of cations at the solid / solid interface; on the other hand, the introduction of functional electron-donating groups limits TFSI. - The movement of these molecules significantly increases the migration rate of lithium ions. At 60℃, the ionic conductivity of the La(OH)3–NH2 system can reach 9.6 × 10⁻⁶. -4 Compared to the blank electrolyte, the ionic conductivity (S / cm) is significantly improved. The lithium-ion transference number can be increased from 0.20 to 0.51.

[0016] 3. The PEO-based solid electrolyte constructed from multifunctional La(OH)3 nanofiber filler enables lithium metal batteries based on LiFePO4 (LFP) cathodes to exhibit excellent cycling performance at high rates. After 350 cycles at 6C, the capacity retention rate is 64.4%, and after 600 cycles at 12C, the capacity retention rate is 63.4%.

[0017] In summary, the product proposed in this embodiment has good application prospects and practical value. The functional lanthanum hydroxide composite PEO-based solid electrolyte for solid-state batteries prepared in this embodiment is a high-rate solid electrolyte with broad application prospects in high-rate solid-state batteries.

[0018] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the molar ratio of La(NO3)3·6H2O to the volume ratio of deionized water in step one ① is 1 mmol:(6~9) mL. Everything else is the same as in Specific Implementation Method One.

[0019] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that the mass ratio of sodium hydroxide to potassium hydroxide in step one, ②, is 1:(1~1.2). Everything else is the same as in Specific Implementation Method One or Two.

[0020] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the volume ratio of the La(NO3)3 solution to the NaOH / KOH mixture in step one ③ is 1 mL:(7~8) g. Everything else is the same as in Specific Implementation Methods One to Three.

[0021] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that: the preheating and heat preservation described in step one ③ is specifically carried out at a temperature of 190℃~210℃ for 25min~35min; the heating reaction described in step one ③ is specifically carried out at a temperature of 190℃~210℃ for 20h~25h. Everything else is the same as in Specific Implementation Methods One to Four.

[0022] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that: the mass ratio of La(OH)3 nanofibers to ethanol in step one (⑤) is 1 g:(75~85) mL; the mass ratio of La(OH)3 nanofibers to APTES in step one (⑤) is 1 g:(0.45~0.55) mL. Everything else is the same as in Specific Implementation Methods One to Five.

[0023] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that the reaction described in step one (⑤) is carried out at a temperature of 150℃ to 280℃ for 4 to 5 hours. Everything else is the same as in Specific Implementation Methods One to Six.

[0024] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in the following ways: Step 1, ④, involves centrifugal washing using deionized water and hot water at 40℃~60℃, repeated at 6000rpm~7000rpm until the pH value reaches 7; Step 1, ⑤, involves washing repeatedly with deionized water, then placing the product in a vacuum oven at 45℃~60℃ for 8~12 hours; Step 2, ②, involves vacuum drying in a vacuum oven at 45℃~60℃ for 20~24 hours. The rest is the same as Specific Implementation Methods One to Seven.

[0025] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that: the mass ratio of the La(OH)3-NH2 two-dimensional fiber filler to the volume ratio of acetonitrile in step two① is 1g:(72~74)mL; the mass ratio of PEO to LiTFSI in step two① is (0.45~0.55):1; and the mass of the La(OH)3-NH2 two-dimensional fiber filler in step two① is 5%~20% of the mass of PEO. Everything else is the same as in Specific Implementation Methods One to Eight.

[0026] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that: in step two ②, the mixture is left to stand at room temperature for 24 to 36 hours. Everything else is the same as in Specific Implementation Methods One to Nine.

[0027] The beneficial effects of the present invention are verified using the following embodiments: Example 1: A method for preparing a functional lanthanum hydroxide composite PEO-based solid electrolyte for solid-state batteries, comprising the following steps: I. Preparation of La(OH)3-NH2 nanofibers modified with functional groups: ① Mix 1.5 mmol La(NO3)3·6H2O with 9 mL of deionized water to obtain a La(NO3)3 solution; ② Mix 26.16g of sodium hydroxide and 27.81g of potassium hydroxide to obtain a NaOH / KOH mixture; ③ Mix 7 mL of La(NO3)3 solution with 54 g of NaOH / KOH mixture evenly, preheat at 200℃ for 30 min, then shake well and heat at 200℃ for 24 h, and finally cool to room temperature to obtain the reaction product. ④ Filter the reaction product, and then wash it repeatedly by centrifugation at 7000 rpm using deionized water and hot water at 45℃ until the pH value is 7, to obtain La(OH)3 nanofibers. ⑤ Dissolve 0.5g of La(OH)3 nanofibers in 40mL of ethanol to obtain a La(OH)3 solution. Add 0.25mL of APTES to the La(OH)3 solution and react at 200℃ for 4h. Finally, filter the solution, wash it repeatedly with deionized water, and then place it in a vacuum oven at 60℃ for vacuum drying for 12h to obtain La(OH)3-NH2 two-dimensional fiber filler. II. Preparation of PEO-based composite solid electrolytes: ① Add 0.5435g of La(OH)3-NH2 two-dimensional fiber filler to 40mL of acetonitrile and mix well to obtain La(OH)3-NH2 solution. Then dissolve 2g of LiTFSI and 1.09g of PEO in the La(OH)3-NH2 solution and stir well to obtain a homogeneous solution. ② Pour the uniform solution onto a polytetrafluoroethylene plate, then place it in a vacuum oven at 60°C and vacuum dry for 24 hours. Finally, let it stand at room temperature for 24 hours to obtain a La(OH)3-NH2-doped PEO solid electrolyte, named LNPE-15. The mass of the La(OH)3-NH2 two-dimensional fiber filler mentioned in step 2① is 15% of the mass of PEO.

[0028] Example 2: This comparative experiment differs from Example 1 in that: the mass of the La(OH)3-NH2 two-dimensional fiber filler in step 2① is 20% of the mass of PEO; and the La(OH)3-NH2-doped PEO solid electrolyte prepared in step 2② is named LNPE-20. Everything else is the same as in Example 1.

[0029] Example 3: This comparative experiment differs from Example 1 in that: the mass of the La(OH)3-NH2 two-dimensional fiber filler mentioned in step 2① is 10% of the mass of PEO; and the La(OH)3-NH2-doped PEO solid electrolyte prepared in step 2② is named LNPE-10. Everything else is the same as in Example 1.

[0030] Example 4: This comparative experiment differs from Example 1 in that: the mass of the La(OH)3-NH2 two-dimensional fiber filler mentioned in step 2① is 5% of the mass of PEO; and the La(OH)3-NH2-doped PEO solid electrolyte prepared in step 2② is named LNPE-5. Everything else is the same as in Example 1.

[0031] Comparative Experiment 1: This comparative experiment differs from Example 1 in that: step 2① omits the addition of the La(OH)3-NH2 two-dimensional fiber filler; step 2② prepares an undoped solid electrolyte, named PEO:LiTFSI. Everything else is the same as in Example 1.

[0032] Comparative Experiment 2: This comparative experiment differs from Example 1 in that: the La(OH)3 prepared in step 1④ was dried in a vacuum oven at 60℃ for 12 hours to obtain dried La(OH)3; in step 2①, the dried La(OH)3-NH2 two-dimensional fiber filler was replaced with the dried La(OH)3; in step 2②, a La(OH)3-doped solid electrolyte was prepared and named LPE-15. Everything else was the same as in Example 1.

[0033] Figure 1 The image shows the XRD pattern of the La(OH)3 nanofibers prepared in step 4 of Example 1. As can be seen from the image, the characteristic peaks of the obtained sample correspond to La(OH)3 (PDF#06–0585), and it can be clearly seen that the crystallinity of the sample is high, indicating that La(OH)3 was successfully synthesized.

[0034] Figure 2 The image shows a TEM image of the La(OH)3 nanofibers prepared in step 4 of Example 1. As can be seen from the image, the average diameter of the obtained La(OH)3 nanofibers is 300 nm, and the length is over 10 μm. This high aspect ratio nanofiber structure can form a three-dimensional continuous ion transport channel in an all-solid-state lithium battery, further improving electrochemical stability and lithium-ion conductivity.

[0035] Figure 3 The image shown is an HRTEM image of the La(OH)3 nanofibers prepared in step 4 of Example 1. The lattice spacing of the prepared La(OH)3 nanofibers is 0.3268 nm, which can be well matched to the (110) lattice plane of the hexagonal phase of La(OH)3.

[0036] Figure 4The image shows the elemental scattering pattern of the La(OH)3 nanofibers prepared in step 4 of Example 1. As can be seen from the image, the uniform distribution of La and O in La(OH)3 indicates the successful preparation of La(OH)3.

[0037] Figure 5 The image shows the ESR (Enhanced Power Reduction) spectrum of the La(OH)3 nanofibers prepared in step 4 of Example 1. The test results show that the ESR signal dominates at g=2.008. Studies indicate that the signal closest to the free electron from the oxygen vacancy should be generated at g=2.0. The signal at g=2.008 is related to the free electron generated by the oxygen vacancy. The results suggest that surface oxygen vacancies are generated during the preparation of La(OH)3.

[0038] Figure 6 The images show infrared spectroscopy. Image 1 shows the La(OH)3 nanofibers prepared in step 4 of Example 1, and image 2 shows the La(OH)3-NH2 two-dimensional fiber filler prepared in step 5 of Example 1. (1560cm) -1 The vibrational absorption peak at the point is related to the bending vibrational absorption peak of -NH2, indicating that -NH2 has been successfully modified into La(OH)3 nanofibers.

[0039] Figure 7 The image shows the elemental scattering spectrum of the La(OH)3-NH2 two-dimensional fiber filler prepared in step 1⑤ of Example 1. The elemental spectrum shows clear La, O, and N elemental signals in the La(OH)3-NH2 nanofibers, indicating the successful modification of the La(OH)3 nanofibers by -NH2.

[0040] Figure 8 The images show the XRD patterns of the solid electrolytes. 1 shows PEO:LiTFSI prepared in Comparative Experiment 1, and 2 shows LNPE-15 prepared in Example 1. LNPE-15 is a perfect match to the PDF card. It can also be seen that the addition of filler significantly inhibits the crystallization of PEO, which is beneficial to lithium ion migration.

[0041] Figure 9 The thermogravimetric analysis (TGA) diagrams for solid electrolytes are shown below. 1 represents LNPE-20 prepared in Example 2, 2 represents LNPE-15 prepared in Example 1, 3 represents LNPE-10 prepared in Example 3, 4 represents LNPE-5 prepared in Example 4, and 5 represents PEO:LiTFSI prepared in Comparative Experiment 1. With the addition of functional La(OH)3-NH2, the TGA of LNPE-x... mThe significant reduction indicates that LNPE-x has a significant inhibitory effect on PEO crystallization, and the proportion of amorphous PEO molecules increases, leading to a decrease in the melting point and an increase in the mobility of polymer molecular chain segments. Furthermore, it lowers the melting point of the solid electrolyte to as low as 45.1℃, greatly increasing the disorder of the solid electrolyte under the battery's 60℃ operating conditions, which facilitates lithium-ion migration; simultaneously, it improves the contact compatibility between the solid electrolyte and the electrode.

[0042] Figure 10 This is a scanning electron microscope (SEM) image of LNPE-15 prepared in Example 1. As can be seen from the image, La(OH)3-NH2 is uniformly distributed in the PEO substrate.

[0043] Figure 11 The images show the LSV (Laser Vapor Spectrometry) of the solid electrolytes at 60 °C. 1 shows the PEO:LiTFSI prepared in Comparative Experiment 1, 2 shows LPE-15 prepared in Comparative Experiment 2, and 3 shows LNPE-15 prepared in Example 1. To verify the electrochemical stability window of the solid electrolytes, linear sweep voltammetry was performed. The results showed that the electrochemical stability window of all solid electrolytes was improved after the addition of inorganic fillers. The electrochemical window of LNPE-15 was 5.64 V, which was attributed to the introduction of La(OH)3-NH2 filler and the interaction between La(OH)3-NH2 and TFSI. - The interaction between anions and Lewis acids and bases.

[0044] LFP|Li batteries were fabricated using LNPE-15, PEO:LiTFSI, and LPE-15 solid electrolytes, as follows: 0.012 g of cathode material (LiFePO4), 0.004 g of conductive agent (super p), and 0.004 g of PPVDF were mixed in 0.5 mL of N-methylpyridinium to obtain a mixture. This mixture was then transferred to an Al foil and dried in a vacuum oven to obtain the cathode electrode. The cathode electrode was cut, and finally, a full cell containing a cathode, electrolyte membrane, and lithium metal (Li) was assembled in an argon-filled glove box, yielding LFP|Li batteries based on LNPE-15 solid electrolyte, LFP|Li batteries based on LPE-15 solid electrolyte, and LFP|Li batteries based on PEO:LiTFSI solid electrolyte. The cycle performance and rate performance of the full cells were tested using a LAND battery testing system.

[0045] Figure 12The figures show the rate curves of LFP|Li batteries from 0.2C to 6C at 60℃. Figure 1 shows an LFP|Li battery based on LNPE-15 solid electrolyte, Figure 2 shows an LFP|Li battery based on LPE-15 solid electrolyte, and Figure 3 shows an LFP|Li battery based on PEO:LiTFSI solid electrolyte. As the current increases, the capacity of the LNPE-15-based battery remains stable, still reaching 100 mAh g at 3C. –1 The capacity of PEO:LiTFSI decreased significantly, falling below 30 mAh g at 3C. –1 .

[0046] Figure 13 The figure shows the charge-discharge curves of the LFP|Li battery based on LNPE-15 solid electrolyte at 60℃ and 12C. As can be seen from the figure, the LFP|Li battery based on LNPE-15 solid electrolyte can maintain 67.8% capacity even after 500 cycles at a high rate current of 12C.

[0047] Figure 14 The figures show the long-term cycling performance of LFP|Li batteries at 60℃ and 12C. 1 represents an LFP|Li battery based on LNPE-15 solid electrolyte, 2 represents an LFP|Li battery based on LPE-15 solid electrolyte, and 3 represents an LFP|Li battery based on PEO:LiTFSI solid electrolyte. The LFP|Li battery with LNPE-15 solid electrolyte retains 63.4% of its capacity after 600 cycles at 12C, significantly outperforming both the LPE-15 solid electrolyte without functional group modification and the undoped PEO:LiTFSI solid electrolyte.

[0048] Figure 15 The graph shows the long-term cycling performance of LFP|Li batteries at 60℃ and 6C. 1 represents an LFP|Li battery based on LNPE-15 solid electrolyte, 2 represents an LFP|Li battery based on LPE-15 solid electrolyte, and 3 represents an LFP|Li battery based on PEO:LiTFSI solid electrolyte. The LFP|Li battery with LNPE-15 solid electrolyte retains 64.4% of its capacity after 350 cycles at 6C, significantly outperforming both the LPE-15 solid electrolyte without functional group modification and the undoped PEO:LiTFSI solid electrolyte.

[0049] Figure 16The images show the EIS curves of LFP|Li batteries at 60℃. Figure 1 shows an LFP|Li battery based on LNPE-15 solid-state electrolyte; Figure 2 shows an LFP|Li battery based on LPE-15 solid-state electrolyte; and Figure 3 shows an LFP|Li battery based on PEO:LiTFSI solid-state electrolyte. The curves show that the all-solid-state battery constructed with LNPE-15 solid-state electrolyte exhibits the highest lithium-ion transport efficiency, with an ionic conductivity reaching 9.6 × 10⁻⁶. -4 S / cm −1 .

[0050] Figure 17 The time-current curves of LFP|Li batteries based on LNPE-15 solid electrolyte are shown at 10 mV; Li solid electrolytes are studied... + To verify Li + Transmission efficiency. The Li of LNPE-15 + The transfer number is 0.51, which increases the interfacial area for lithium salt dissociation.

[0051] Figure 18 The time-current curves of LFP|Li batteries based on PEO:LiTFSI solid electrolyte are shown at 10 mV; Li + The transfer number was 0.2, which is significantly lower than that of LNPE-15 solid electrolyte.

Claims

1. A method for preparing a functional lanthanum hydroxide composite PEO-based solid electrolyte for solid-state batteries, characterized in that... It is done in the following steps: I. Preparation of La(OH)3-NH2 nanofibers modified with functional groups: ① Mix La(NO3)3·6H2O with deionized water to obtain a La(NO3)3 solution; ② Mix sodium hydroxide and potassium hydroxide to obtain a NaOH / KOH mixture; ③ Mix the La(NO3)3 solution with the NaOH / KOH mixture until homogeneous and preheat to a warm temperature. Then shake well and heat to react. Finally cool to room temperature to obtain the reaction product. ④ The reaction product was filtered and centrifuged and washed to obtain La(OH)3 nanofibers; ⑤ Dissolve La(OH)3 nanofibers in ethanol to obtain La(OH)3 solution, add APTES dropwise to the La(OH)3 solution to react, and finally filter, wash and dry to obtain La(OH)3-NH2 one-dimensional fiber filler; II. Preparation of PEO-based composite solid electrolytes: ① Add the La(OH)3-NH2 one-dimensional fiber filler to acetonitrile and mix evenly to obtain a La(OH)3-NH2 solution. Then dissolve LiTFSI and PEO in the La(OH)3-NH2 solution and stir evenly to obtain a homogeneous solution. ② Pour the uniform solution onto a polytetrafluoroethylene plate, then vacuum dry and allow it to stand at room temperature to complete the preparation method of functional lanthanum hydroxide composite PEO-based solid electrolyte for solid-state batteries.

2. The method for preparing a functional lanthanum hydroxide composite PEO-based solid electrolyte for solid-state batteries according to claim 1, characterized in that... The molar ratio of La(NO3)3·6H2O to the volume ratio of deionized water in step 1① is 1 mmol: (6~9) mL.

3. The method for preparing a functional lanthanum hydroxide composite PEO-based solid electrolyte for solid-state batteries according to claim 1, characterized in that... The mass ratio of sodium hydroxide to potassium hydroxide mentioned in step 1② is 1:(1~1.2).

4. The method for preparing a functional lanthanum hydroxide composite PEO-based solid electrolyte for solid-state batteries according to claim 1, characterized in that... The volume ratio of the La(NO3)3 solution to the NaOH / KOH mixture in step 1③ is 1 mL:(7~8) g.

5. The method for preparing a functional lanthanum hydroxide composite PEO-based solid electrolyte for solid-state batteries according to claim 1, characterized in that... The preheating and heat preservation mentioned in step 1③ specifically refers to preheating and heat preservation for 25 min to 35 min at a temperature of 190℃ to 210℃; the heating reaction mentioned in step 1③ specifically refers to heating and reacting for 20 h to 25 h at a temperature of 190℃ to 210℃.

6. The method for preparing a functional lanthanum hydroxide composite PEO-based solid electrolyte for solid-state batteries according to claim 1, characterized in that... The mass ratio of La(OH)3 nanofibers to ethanol in step 1, ⑤ is 1 g:(75~85) mL; the mass ratio of La(OH)3 nanofibers to APTES in step 1, ⑤ is 1 g:(0.45~0.55) mL.

7. The method for preparing a functional lanthanum hydroxide composite PEO-based solid electrolyte for solid-state batteries according to claim 1, characterized in that... The reaction described in step 1, ⑤ is specifically carried out at a temperature of 150℃~280℃ for 4h~5h.

8. The method for preparing a functional lanthanum hydroxide composite PEO-based solid electrolyte for solid-state batteries according to claim 1, characterized in that... The centrifugal washing described in step 1, ④ specifically involves using deionized water and hot water at a temperature of 40℃~60℃, centrifuging and washing multiple times at a speed of 6000rpm~7000rpm until the pH value is 7; the washing and drying described in step 1, ⑤ specifically involves repeatedly rinsing with deionized water, and then placing it in a vacuum oven at a temperature of 45℃~60℃ for vacuum drying for 8h~12h; the vacuum drying described in step 2, ② specifically involves placing it in a vacuum oven at a temperature of 45℃~60℃ for vacuum drying for 20h~24h.

9. The method for preparing a functional lanthanum hydroxide composite PEO-based solid electrolyte for solid-state batteries according to claim 1, characterized in that... In step 2①, the mass ratio of the La(OH)3-NH2 one-dimensional fiber filler to the volume ratio of acetonitrile is 1 g: (72~74) mL; the mass ratio of PEO to LiTFSI in step 2① is (0.45~0.55):1; and the mass of the La(OH)3-NH2 one-dimensional fiber filler in step 2① is 5%~20% of the mass of PEO.

10. The method for preparing a functional lanthanum hydroxide composite PEO-based solid electrolyte for solid-state batteries according to claim 1, characterized in that... In step 2②, let it stand at room temperature for 24h~36h.

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