Fibrous composite solid electrolyte and preparation method and application thereof

Abstract

The application provides a fibrous composite solid electrolyte, a preparation method and application thereof, the fibrous composite solid electrolyte comprises an electron conductive part and an ion conductive part, the electron conductive part has a reticular structure, and the material of the ion conductive part is filled in the pores of the reticular structure; the preparation raw material of the electron conductive part comprises a carbon material precursor, and the material of the ion conductive part comprises an inorganic solid electrolyte; the fibrous composite solid electrolyte has the dual conduction effect of ions and electrons, combines long-range conduction and short-range conduction, has high conductivity and low interface impedance, can be used as a conductive agent of an electrode material, and makes the battery prepared by using the electrode material have excellent electrical properties.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, specifically relating to a fibrous composite solid electrolyte, its preparation method, and its application. Background Technology

[0002] The positive and negative electrode materials of alkali metal batteries are mostly composed of active materials, conductive agents, and binders. Among them, the conductive agent provides electronic conductivity and becomes a key component in the conductive network of the positive and negative electrode materials. Ionic conductivity is solved by the electrolyte that permeates into it. This combination of ionic and electronic conductivity can basically handle the conventional charge and discharge process when the electrode load is relatively small. However, it is somewhat affected for the charge and discharge performance of thick electrodes that are aimed at pursuing high energy density batteries. At the same time, if it is a solid electrode design, the battery itself does not add electrolyte, so it is necessary to introduce the design of ionic conductivity pathways.

[0003] Solid electrolytes are the core component of solid-state and semi-solid-state batteries. They mainly fall into two categories: polymer solid electrolytes and inorganic solid electrolytes, primarily serving as carriers for ion transport. Common inorganic solid electrolytes include sulfide solid electrolytes and oxide solid electrolytes. Among them, oxide solid electrolyte materials possess advantages such as high safety, good stability, low cost, and environmental friendliness, mainly including NASICON-type oxide electrolytes, garnet-type oxide electrolytes, and perovskite-type oxide electrolytes. Sulfide solid electrolytes exhibit characteristics such as high room-temperature ionic conductivity, low electronic conductivity, and good mechanical properties. Oxide and sulfide solid electrolytes are also the inorganic solid electrolyte materials that have received the most attention in the development of all-solid-state batteries. CN111816916A discloses a composite solid electrolyte membrane, its preparation method, and a lithium-ion battery. This invention proposes a composite solid electrolyte membrane comprising a polymer electrolyte and inorganic electrolyte fibers dispersed in the polymer electrolyte. The angle θ between the length direction of the inorganic electrolyte fibers and the thickness direction of the composite solid electrolyte membrane satisfies: 0°≤θ≤30°. The composite solid electrolyte membrane obtained by this invention improves the ionic conductivity and mechanical strength of the composite solid electrolyte membrane by designing the material composition and structure.

[0004] However, due to the high rigidity of inorganic solid electrolytes, they are not conducive to pore filling and interfacial contact with electrodes, and they cannot provide long-range conductivity. Meanwhile, polymer solid electrolytes often have low conductivity. Therefore, neither existing inorganic solid electrolytes nor polymer solid electrolytes can simultaneously possess excellent conductivity and low interfacial impedance.

[0005] Therefore, developing a fibrous composite solid electrolyte with high conductivity, good toughness, and low interfacial impedance with electrodes is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a fibrous composite solid electrolyte and its preparation method. The fibrous composite solid electrolyte combines electronic conductivity and ionic conductivity, thus possessing the advantages of both. It achieves dual conduction of ions and electrons, exhibits high conductivity and low interfacial impedance, thereby enabling batteries prepared using it to have excellent electrical performance.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a fibrous composite solid electrolyte, the fibrous composite solid electrolyte comprising an electronically conductive portion and an ionicly conductive portion;

[0009] The electronically conductive portion has a mesh structure, and the material of the ionically conductive portion fills the pores of the mesh structure;

[0010] The raw materials for preparing the electronically conductive part include carbon material precursors, and the materials for the ionicly conductive part include inorganic solid electrolytes.

[0011] The fibrous composite solid electrolyte provided by this invention includes an electronically conductive portion and an ionicly conductive portion. The electronically conductive portion has a continuous mesh structure with a large number of continuous voids. The material of the ionicly conductive portion fills the voids, thereby achieving a dual conductivity effect by combining electronic and ionic conductivity. This improves the conductivity of both ionic and electronic conduction and combines long-range and short-range conductivity. As a result, the fibrous composite solid electrolyte has high conductivity, high compaction density, good flexibility, and suitable porosity, while also exhibiting low impedance at the electrode interface.

[0012] The fibrous composite solid electrolyte provided by this invention can completely or partially replace the conductive agent in the electrode material, reducing the amount of traditional conductive agent used, thereby helping to increase the mass ratio of active material in the electrode material and reduce the amount of electrolyte used. It is particularly suitable for use with thick electrodes (>200μm) and can make the battery prepared using the electrode material have excellent electrical performance.

[0013] Preferably, the diameter of the fibrous composite solid electrolyte is 5-5000 nm, such as 10 nm, 50 nm, 100 nm, 500 nm, 1000 nm, 2000 nm, 3000 nm or 4000 nm, and more preferably 50-500 nm, such as 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm or 450 nm.

[0014] Preferably, the aspect ratio of the fibrous composite solid electrolyte is 2 to 100, such as 10, 20, 30, 40, 50, 60, 70, 80 or 90, and more preferably 5 to 50.

[0015] Preferably, the porosity of the fibrous composite solid electrolyte is less than 20%, for example, 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12%, 11%, or 10%.

[0016] Preferably, the mass ratio of the electronically conductive portion to the ionicly conductive portion is 1:(0.1 to 9), such as 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7 or 1:8, and more preferably 1:(1 to 3.5).

[0017] Preferably, the carbon material precursor comprises a polymer material.

[0018] Preferably, the polymer material includes any one or a combination of at least two of polyacrylonitrile, polyvinylpyrrolidone, polyurethane, or polyimide.

[0019] Preferably, the inorganic solid electrolyte includes any one or a combination of at least two of oxide solid electrolytes, sulfide solid electrolytes, or chloride solid electrolytes.

[0020] Preferably, the oxide solid electrolyte includes any one or a combination of at least two of the following: NASICON type oxide solid electrolyte, garnet type oxide solid electrolyte, or perovskite type oxide solid electrolyte.

[0021] Preferably, the NASICON-type oxide solid electrolyte includes any one or a combination of at least two of lithium aluminum titanium phosphate, lithium titanium phosphate, lithium germanium phosphate, or lithium zirconium phosphate.

[0022] Preferably, the garnet-type oxide solid electrolyte comprises lithium zirconium oxide (LNO).

[0023] Preferably, the perovskite-type oxide solid electrolyte comprises lithium lanthanum titanium oxide.

[0024] Preferably, the sulfide solid electrolyte includes a Li-PS type solid electrolyte, Li 11-n M 2-n P 1+n S 12 Any one or a combination of at least two of the following: a solid electrolyte of type Li6PS5X or a solid electrolyte of type Li6PS5X.

[0025] Where n is greater than 0 and less than or equal to 1, M is selected from Ge, Sn or Si, and X is selected from Cl, Br or I.

[0026] Preferably, the Li-PS type solid electrolyte includes Li3PS4 and / or Li7P3S 11 .

[0027] Preferably, the Li 11-n M 2-n P 1+n S 12 Solid electrolytes include Li2S-GeS2-P2S5.

[0028] Preferably, the material of the electronically conductive portion further includes carbon nanotubes;

[0029] Preferably, the mass ratio of the carbon material precursor to the carbon nanotube is 1:(0.1-9), such as 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7 or 1:8.

[0030] In a second aspect, the present invention provides a method for preparing a fibrous composite solid electrolyte as described in the first aspect, the method comprising the following steps:

[0031] (1) Dissolve carbon material precursor and optionally carbon nanotubes in a solvent, add inorganic solid electrolyte and mix to obtain electrospinning solution;

[0032] (2) The electrospinning solution obtained in step (1) is electrospinned, and after stabilization, carbonization and shearing, the fibrous composite solid electrolyte is obtained.

[0033] The preparation method provided by this invention first dissolves a carbon material precursor and optionally carbon nanotubes in a solvent, then adds an inorganic solid electrolyte for mixing, so that the powder particles of the inorganic solid electrolyte are uniformly dispersed in the liquid to obtain an electrospinning solution. Then, the obtained electrospinning solution is spun into composite fibers by electrospinning. The obtained composite fibers are then subjected to stabilization and carbonization treatments, so that the carbon material precursor forms carbon material, which, together with the optionally carbon nanotubes, forms an electronically conductive part with a network structure, while the inorganic solid electrolyte fills the pores of the network structure as an ion-conducting part. The preparation method is simple and suitable for mass industrial production.

[0034] Preferably, the solvent in step (1) includes N,N-dimethylformamide.

[0035] Preferably, the mixing in step (1) is carried out under stirring conditions.

[0036] Preferably, the mixing time in step (1) is 3 to 5 hours, such as 3.2 hours, 3.4 hours, 3.6 hours, 3.8 hours, 4 hours, 4.2 hours, 4.4 hours, 4.6 hours or 4.8 hours.

[0037] Preferably, the mixing temperature in step (1) is 50 to 70°C, such as 52°C, 54°C, 56°C, 58°C, 60°C, 62°C, 64°C, 66°C, or 68°C.

[0038] Preferably, the voltage of electrospinning in step (2) is 50 to 70 kV, such as 52 kV, 54 kV, 56 kV, 58 kV, 60 kV, 62 kV, 64 kV, 66 kV or 68 kV.

[0039] Preferably, the spinning distance of the electrospinning in step (2) is 10 to 20 cm, such as 11 cm, 12 cm, 13 cm, 14 cm, 15 cm, 16 cm, 17 cm, 18 cm or 19 cm.

[0040] Preferably, the stabilization treatment and carbonization treatment in step (2) are both carried out in a tube furnace.

[0041] Preferably, the stabilization treatment and carbonization treatment in step (2) are both carried out under inert gas protection conditions.

[0042] Preferably, the inert gas includes argon.

[0043] Preferably, the stabilization treatment temperature in step (2) is 400-500℃, such as 410℃, 420℃, 430℃, 440℃, 450℃, 460℃, 470℃, 480℃ or 490℃.

[0044] Preferably, the stabilization treatment time in step (2) is 1.5 to 2.5 hours, such as 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours, 2 hours, 2.1 hours, 2.2 hours, 2.3 hours or 2.4 hours.

[0045] Preferably, the carbonization temperature in step (2) is 800 to 1000°C, such as 820°C, 840°C, 860°C, 880°C, 900°C, 920°C, 940°C, 960°C or 980°C.

[0046] Preferably, the carbonization treatment time in step (2) is 1.5 to 2.5 hours, such as 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours, 2 hours, 2.1 hours, 2.2 hours, 2.3 hours or 2.4 hours.

[0047] Preferably, the shearing process in step (2) includes high-energy ball milling.

[0048] As a preferred embodiment of the present invention, the preparation method includes the following steps:

[0049] (1) Dissolve carbon material precursor and optionally carbon nanotubes in a solvent, add inorganic solid electrolyte and stir at 50-70°C for 3-5 hours to obtain electrospinning solution;

[0050] (2) The electrospinning solution obtained in step (1) is electrospinned at a voltage of 50-70kV with a spinning distance of 10-20cm. Under argon protection, it is stabilized at 400-500℃ for 1.5-2.5h, carbonized at 800-1000℃ for 1.5-2.5h, and then ball-milled at high energy to obtain the fibrous composite solid electrolyte.

[0051] Thirdly, the present invention provides an electrode material comprising an active substance, a binder, and a fibrous composite solid electrolyte as described in the first aspect.

[0052] Preferably, the electrode material includes a positive electrode material or a negative electrode material.

[0053] Fourthly, the present invention provides an application of the electrode material as described in the third aspect in an alkali metal battery.

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] (1) The fibrous composite solid electrolyte provided by the present invention includes an electronically conductive part and an ionicly conductive part. The electronically conductive part has a continuous mesh structure with a large number of continuous voids. The material of the ionicly conductive part fills the voids, thereby enabling the fibrous composite solid electrolyte to achieve dual conduction of electronic and ionic conductivity, improving the conductivity of both ionic and electronic conduction, and combining long-range and short-range conductivity. This results in a fibrous composite solid electrolyte with high compaction density, good flexibility, suitable porosity, and high conductivity, while having low impedance at the electrode interface.

[0056] (2) The fibrous composite solid electrolyte provided by the present invention can replace or partially replace the conductive agent in the electrode material, reduce the amount of traditional conductive agent, and thus help to increase the mass ratio of active material in the electrode material and reduce the amount of electrolyte. It is particularly suitable for use with thick electrodes and can also effectively improve the electrical performance of the battery prepared using the electrode material. Specifically, the lithium-ion battery prepared using the fibrous composite solid electrolyte provided by the present invention has an interfacial impedance of only 4.3 to 4.6 mΩ and a capacity retention rate of 92 to 93% after 500 cycles. Detailed Implementation

[0057] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0058] Example 1

[0059] A fibrous composite solid electrolyte, composed of an electronically conductive portion and an ionicly conductive portion in a mass ratio of 1:1, has a diameter of 250 nm and an aspect ratio of 50. Its preparation method includes the following steps:

[0060] (1) Dissolve 22g of polyacrylonitrile (Aladdin Reagent (Shanghai) Co., Ltd., P303197) and 3g of conductive carbon nanotubes (Qingdao Haoxin New Energy Technology Co., Ltd., HX-NS) in 200mL of N,N-dimethylformamide, add 10g of lithium titanium aluminum phosphate and mix magnetically at 60℃ for 4h to obtain electrospinning stock solution.

[0061] (2) The electrospinning solution obtained in step (1) is electrospinned. The electrospinning voltage is 60kV and the spinning distance is 15cm. Then it is placed in a tube furnace and stabilized at 450℃ for 2h and carbonized at 900℃ for 2h in an argon atmosphere. The fibrous composite solid electrolyte is obtained by high-energy ball milling.

[0062] Example 2

[0063] A fibrous composite solid electrolyte, composed of electronically and ionicly conductive components in a mass ratio of 1:2, has a diameter of 50 nm and an aspect ratio of 5. Its preparation method includes the following steps:

[0064] (1) Dissolve 12g of polyacrylonitrile (Aladdin Reagent (Shanghai) Co., Ltd., P303197) and 3g of conductive carbon nanotubes (Qingdao Haoxin New Energy Technology Co., Ltd., HX-NS) in 180mL of N,N-dimethylformamide, add 10g of lithium titanium aluminum phosphate and mix magnetically at 50℃ for 5h to obtain electrospinning stock solution.

[0065] (2) The electrospinning solution obtained in step (1) is electrospinned. The electrospinning voltage is 50kV and the spinning distance is 15cm. Then it is placed in a tube furnace and stabilized at 400℃ for 2.5h and carbonized at 1000℃ for 1.5h in an argon atmosphere. The fibrous composite solid electrolyte is obtained by high-energy ball milling.

[0066] Example 3

[0067] A fibrous composite solid electrolyte, composed of electronically and ionicly conductive components in a mass ratio of 2:3, has a diameter of 500 nm and an aspect ratio of 50. Its preparation method includes the following steps:

[0068] (1) Dissolve 18g of polyvinylpyrrolidone (Aladdin Reagent (Shanghai) Co., Ltd., K88-96) and 3g of conductive carbon nanotubes (Qingdao Haoxin New Energy Technology Co., Ltd., HX-NS) in 200mL of N,N-dimethylformamide, add 12g of lithium lanthanum titanium oxide and mix magnetically at 70℃ for 3h to obtain electrospinning solution;

[0069] (2) The electrospinning solution obtained in step (1) is electrospinned. The electrospinning voltage is 70kV and the spinning distance is 15cm. Then it is placed in a tube furnace and stabilized at 500℃ for 1.5h and carbonized at 800℃ for 2.5h in an argon atmosphere. The fibrous composite solid electrolyte is obtained by high-energy ball milling.

[0070] Example 4

[0071] A fibrous composite solid electrolyte differs from Example 1 only in that it does not contain carbon nanotubes; all other structures, materials, and preparation methods are the same as in Example 1.

[0072] Comparative Example 1

[0073] A fibrous solid electrolyte with a diameter of 250 nm and an aspect ratio of 50 is prepared by the following steps:

[0074] (1) Dissolve 22g of polyacrylonitrile (Aladdin Reagent (Shanghai) Co., Ltd., P303197) and 3g of conductive carbon nanotube (Qingdao Haoxin New Energy Technology Co., Ltd., HX-NS) in 200mL of N,N-dimethylformamide to obtain electrospinning solution;

[0075] (2) The electrospinning solution obtained in step (1) is electrospinned. The electrospinning voltage is 60kV and the spinning distance is 15cm. Then it is placed in a tube furnace and stabilized at 450℃ for 2h and carbonized at 900℃ for 2h in an argon atmosphere. The fibrous solid electrolyte is obtained by high-energy ball milling.

[0076] Comparative Example 2

[0077] A fibrous solid electrolyte with a diameter of 250 nm and an aspect ratio of 50 is prepared by the following steps:

[0078] (1) Add 12g of lithium titanium aluminum phosphate to 200mL of N,N-dimethylformamide and mix magnetically at 60℃ for 4h to obtain electrospinning solution.

[0079] (2) The electrospinning solution obtained in step (1) is electrospinned. The electrospinning voltage is 60kV and the spinning distance is 15cm. Then it is placed in a tube furnace and stabilized at 450℃ for 2h and carbonized at 900℃ for 2h in an argon atmosphere. The fibrous solid electrolyte is obtained by high-energy ball milling.

[0080] Application Example 1

[0081] A positive electrode sheet, the preparation method of which includes the following steps:

[0082] (1) 41.5g of PVDF and 1.3L of NMP were added to a mixer in sequence and stirred at high speed of 4000rpm and 70rpm for 3h. Then, 10.4g of Super P, 208g of carbon nanotube conductive slurry (solid content of 5%) and 10.4g of fibrous composite solid electrolyte (Example 1) were added in sequence and mixed at high speed for 1h. Then, 2000g of lithium iron phosphate was added and stirred at high speed for 6h to obtain the positive electrode slurry.

[0083] (2) The positive electrode slurry obtained in step (1) is uniformly mixed according to a surface density of 320 g / m³. 2 The coating is applied to aluminum foil, and then cut with a die to obtain the positive electrode sheet.

[0084] Application Examples 2-4

[0085] A positive electrode sheet, which differs from Application Example 1 only in that the fibrous composite solid electrolyte obtained in Examples 2 to 4 is used instead of the fibrous composite solid electrolyte obtained in Example 1, while the other materials and preparation methods are the same as in Application Example 1.

[0086] Application Example 5

[0087] A lithium-ion battery, the manufacturing process of which includes the following steps:

[0088] (1) Preparation of negative electrode slurry: 175.4g of LA132 with a solid content of 15%, 10.5g of CMC and 1.14L of deionized water were added to a mixer in sequence and stirred at high speed of 4000rpm and 70rpm for 3h. Then, 15.8g of Super P was added in sequence and the mixture was stirred at high speed for 1h. Finally, 1000g of artificial graphite was added and stirred at high speed for 6h to obtain the negative electrode slurry.

[0089] (2) Preparation of electrolyte: LiPF6 was dissolved in an electrolyte composed of EC, EMC and DMC in a volume ratio of 1:1:1 in an argon-filled glove box at a concentration of 1 mol / L. The mixture was stirred for 1 h, and then 3 wt% FEC was added and stirred for 3 h to obtain the electrolyte.

[0090] (3) Battery manufacturing: ① The negative electrode slurry is coated, baked and cut to obtain the negative electrode sheet; ② The battery core is made in the following order: the negative electrode sheet is wrapped with a separator, the negative electrode sheet is wrapped with a separator, and the separator is wrapped with a positive electrode sheet (Application Example 1); ③ The electrode tabs are welded to the core, the positive electrode tab is aluminum and the negative electrode tab is nickel / copper plated with nickel; ④ The core is sealed in an aluminum-plastic film, with an opening on the side for subsequent electrolyte injection; ⑤ The sealed battery cell is placed in a 110℃ forced-air oven for baking for 48 hours; ⑥ The baked battery cell is transferred to an electrolyte injection room with a dew point of -30℃ under a low dew point environment and an appropriate amount of electrolyte is injected; ⑦ The battery cell is sealed and then aged, formed and capacity tested to obtain a lithium-ion battery.

[0091] Application Examples 6-8

[0092] A lithium-ion battery differs from Application Example 5 only in that the positive electrode obtained in Application Example 2 to 4 is used to replace the positive electrode obtained in Application Example 1. All other materials and preparation methods are the same as in Application Example 5.

[0093] Comparative application examples 1-2

[0094] A positive electrode sheet, which differs from Application Example 1 only in that the fibrous composite solid electrolyte obtained in Comparative Examples 1 and 2 is used instead of the fibrous composite solid electrolyte obtained in Example 1, while the other materials and preparation methods are the same as in Application Example 1.

[0095] Compare and contrast examples 3-4

[0096] A lithium-ion battery differs from Application Example 5 only in that the positive electrode obtained in Application Example 1 is replaced with the positive electrode obtained in Comparative Application Examples 1-2, while the other materials and preparation methods are the same as in Application Example 5.

[0097] Performance testing:

[0098] (1) Elastic modulus: Mechanical properties were measured using an instrumental nanoindentation device (G200 nanoindenter, KLA) at a constant strain rate of 0.05 s⁻¹. -1 Under the condition, by formula 1 / E r =(1-v 2 ) / E+(1-v i 2 ) / E i Determine the elastic modulus, where v and v i These are the Poisson's ratios of the sample and the indenter, respectively, where Ei is the elastic modulus of the indenter, and E... r =0.5S√(π / A) c S is the unloading slope of the load-displacement curve after the initial pressure head is removed.

[0099] (2) Ionic conductivity: A stainless steel / electrolyte / stainless steel button cell was assembled in a glove box filled with argon gas. After standing for 1 day, an electrochemical AC impedance spectroscopy test was performed using a Bio-logic VMP-300 electrochemical workstation. The frequency range was 7kHz to 500MHz and the test temperature was 30 to 80℃.

[0100] Ionic conductivity (σ) is calculated using σ = L / RS, where L is the electrolyte membrane thickness in mm, R is the electrolyte resistance in ohms, and S is the effective electrode surface area in mm². 2 .

[0101] The solid electrolytes obtained in Examples 1-4 and Comparative Examples 1-2 were tested according to the above test methods, and the test results are shown in Table 1:

[0102] Table 1

[0103] Elastic modulus / GPa Ionic conductivity / S / cm Example 1 126 4.2 x 10 -4 ]]> Example 2 135 <![CDATA[4.1×10 -4 ]]> Example 3 185 <![CDATA[4.0×10 -4 ]]> Example 4 128 <![CDATA[4.1×10 -4 ]]> Comparative Example 1 115 <![CDATA[3.8×10 -4 ]]> Comparative Example 2 113 <![CDATA[3.9×10 -4 ]]>

[0104] As can be seen from the data in Table 1, the fibrous composite solid electrolyte provided by this invention has excellent mechanical and electrical properties; specifically, the fibrous composite solid electrolytes obtained in Examples 1-4 have an elastic modulus of 126-185 GPa and an ionic conductivity of 4.0 × 10⁻⁶. -4 ~4.2×10 -4 The solid electrolytes containing only electronic conductive parts (Comparative Example 1) and solid electrolytes containing only ionic conductive parts (Comparative Example 2) have lower elastic moduli and lower ionic conductivity, indicating that their mechanical and electrical properties are both poor.

[0105] (3) Impedance test: The impedance test is performed using a battery internal resistance tester (Changzhou Hepu Electronic Technology Co., Ltd., CHT3561). Connect the red terminal to the positive terminal and the black terminal to the negative terminal. Select the internal resistance test and then read the value.

[0106] (4) Cyclic performance: Tested using a Xinwei battery tester. The assembled lithium-ion battery was placed on the battery tester, with the red terminal connected to the positive terminal and the black terminal connected to the negative terminal. The battery was then set up as follows: ① Rest for 12 hours; ② Constant current charging, current 0.1C, cutoff voltage 4.2V; ③ Constant current discharging, current 0.1C, cutoff voltage 2.7V; ④ 500 cycles; ⑤ End.

[0107] The lithium-ion batteries provided in Test Cases 5-8 and Comparative Application Examples 3-4 were tested according to the above test methods. The test results are shown in Table 2.

[0108] Table 2

[0109] Interface impedance / mΩ Capacity retention rate / % Application Example 5 4.3 93 Application Example 6 4.4 92 Application Example 7 4.2 93 Application Example 8 4.6 91 Comparative Application Example 3 4.7 89 Comparative Application Example 4 5.2 88

[0110] As can be seen from the data in Table 1, lithium-ion batteries containing the composite solid electrolyte provided by this invention have excellent electrical performance. Specifically, the lithium-ion batteries obtained in Examples 5 to 8 have an interface impedance of only 4.2 to 4.6 mΩ and a capacity retention rate of 92 to 93% after 500 cycles. In contrast, lithium-ion batteries containing only ionic conductive parts and solid electrolytes containing only electronic conductive parts have higher interface impedances and thus lower cycle retention rates, indicating poorer electrical performance.

[0111] As can be seen from Tables 1 and 2 above, the fibrous composite solid electrolyte obtained by combining the electronic and ionic conductive parts has been effectively improved in terms of both mechanical properties and ionic conductivity. At the same time, with the construction of the composite conductive network, the interfacial impedance is reduced to a certain extent, indicating that the addition of the composite solid electrolyte improves the electronic conductivity of the battery.

[0112] The applicant declares that this invention illustrates a fibrous composite solid electrolyte, its preparation method, and its application through the above embodiments. However, this invention is not limited to the above embodiments, meaning that this invention does not necessarily rely on the above embodiments for implementation. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection and disclosure scope of this invention.

Claims

1. A fibrous composite solid electrolyte, characterized in that, The fibrous composite solid electrolyte comprises an electronically conductive portion and an ionicly conductive portion; The electronically conductive portion has a mesh structure, and the material of the ionically conductive portion fills the pores of the mesh structure; The raw materials for preparing the electronically conductive part include carbon material precursors and carbon nanotubes in a mass ratio of 1:(0.1~9), and the materials for the ionically conductive part include inorganic solid electrolytes. The carbon material precursor includes polymer materials.

2. The fibrous composite solid electrolyte according to claim 1, characterized in that, The diameter of the fibrous composite solid electrolyte is 5~5000 nm.

3. The fibrous composite solid electrolyte according to claim 2, characterized in that, The diameter of the fibrous composite solid electrolyte is 50~500 nm.

4. The fibrous composite solid electrolyte according to claim 1, wherein the aspect ratio of the fibrous composite solid electrolyte is 2 to 100.

5. The fibrous composite solid electrolyte according to claim 4, wherein the aspect ratio of the fibrous composite solid electrolyte is 5 to 50.

6. The fibrous composite solid electrolyte according to claim 1, wherein the porosity of the fibrous composite solid electrolyte is less than 20%.

7. The fibrous composite solid electrolyte according to claim 1, characterized in that, The mass ratio of the electronically conductive portion to the ionicly conductive portion is 1:(0.1~9).

8. The fibrous composite solid electrolyte according to claim 7, wherein the mass ratio of the electronically conductive portion to the ionicly conductive portion is 1:(1~3.5).

9. The fibrous composite solid electrolyte according to claim 1, wherein the polymer material comprises any one or a combination of at least two of polyacrylonitrile, polyvinylpyrrolidone, polyurethane, or polyimide.

10. The fibrous composite solid electrolyte according to claim 1, characterized in that, The inorganic solid electrolyte includes any one or a combination of at least two of oxide solid electrolytes, sulfide solid electrolytes, or chloride solid electrolytes.

11. The fibrous composite solid electrolyte according to claim 10, characterized in that, The oxide solid electrolyte includes any one or a combination of at least two of the following: NASICON type oxide solid electrolyte, garnet type oxide solid electrolyte, or perovskite type oxide solid electrolyte.

12. The fibrous composite solid electrolyte according to claim 11, characterized in that, The NASICON-type oxide solid electrolyte includes any one or a combination of at least two of lithium aluminum titanium phosphate, lithium titanium phosphate, lithium germanium phosphate, or lithium zirconium phosphate.

13. The fibrous composite solid electrolyte according to claim 11, characterized in that, The garnet-type oxide solid electrolyte includes zirconium lanthanum lithium oxide.

14. The fibrous composite solid electrolyte according to claim 11, characterized in that, The perovskite-type oxide solid electrolyte includes lithium lanthanum titanium oxide.

15. The fibrous composite solid electrolyte according to claim 10, characterized in that, The sulfide solid electrolyte includes Li-PS type solid electrolyte, Li 11-n M 2-n P 1+n S 12 Any one or a combination of at least two of the following: a solid electrolyte of type Li6PS5X or a solid electrolyte of type Li6PS5X. Where n is greater than 0 and less than or equal to 1, M is selected from Ge, Sn or Si, and X is selected from Cl, Br or I.

16. The fibrous composite solid electrolyte according to claim 15, characterized in that, The Li-PS type solid electrolyte includes Li3PS4 and / or Li7P3S 11 .

17. The fibrous composite solid electrolyte according to claim 15, characterized in that, The Li 11-n M 2-n P 1+n S 12 Solid electrolytes include Li2S-GeS2-P2S5.

18. A method for preparing a fibrous composite solid electrolyte as described in any one of claims 1 to 17, characterized in that, The preparation method includes the following steps: (1) Dissolve carbon material precursors and carbon nanotubes in a solvent, add inorganic solid electrolyte and mix to obtain electrospinning solution; (2) The electrospinning solution obtained in step (1) is electrospinned, and after stabilization, carbonization and shearing, the fibrous composite solid electrolyte is obtained.

19. The preparation method according to claim 18, characterized in that, The solvent in step (1) includes N,N -Dimethylformamide.

20. The preparation method according to claim 18, characterized in that, The mixing in step (1) is carried out under stirring conditions.

21. The preparation method according to claim 18, characterized in that, The mixing time in step (1) is 3 to 5 hours.

22. The preparation method according to claim 18, characterized in that, The mixing temperature in step (1) is 50~70℃.

23. The preparation method according to claim 18, characterized in that, The voltage for electrospinning in step (2) is 50~70 kV.

24. The preparation method according to claim 18, characterized in that, The spinning distance of the electrospinning in step (2) is 10~20 cm.

25. The preparation method according to claim 18, characterized in that, The stabilization and carbonization processes described in step (2) are both carried out in a tube furnace.

26. The preparation method according to claim 18, characterized in that, The stabilization and carbonization processes described in step (2) are both carried out under inert gas protection conditions.

27. The preparation method according to claim 26, characterized in that, The inert gas includes argon.

28. The preparation method according to claim 18, characterized in that, The stabilization treatment in step (2) is carried out at a temperature of 400~500℃.

29. The preparation method according to claim 18, characterized in that, The stabilization process in step (2) takes 1.5 to 2.5 hours.

30. The preparation method according to claim 18, characterized in that, The carbonization temperature in step (2) is 800~1000℃.

31. The preparation method according to claim 18, characterized in that, The carbonization process in step (2) takes 1.5 to 2.5 hours.

32. The preparation method according to claim 18, characterized in that, The shearing process described in step (2) includes high-energy ball milling.

33. An electrode material, characterized in that, The electrode material includes an active substance, a binder, and a fibrous composite solid electrolyte as described in any one of claims 1 to 17.

34. The electrode material according to claim 33, characterized in that, The electrode material includes a positive electrode material or a negative electrode material.

35. The application of an electrode material as described in claim 33 or 34 in an alkali metal battery.