A composite solid electrolyte and its preparation method and application

Abstract

The present invention discloses a composite solid electrolyte, its preparation method, and application. The composite solid electrolyte of the present invention comprises an amorphous nanotube array and a polymer matrix, wherein the polymer matrix is ​​filled inside the nanotubes of the amorphous nanotube array. The composite solid electrolyte of the present invention has the advantages of good electrochemical performance, mechanical rigidity comparable to that of inorganic electrolytes, damping characteristics comparable to those of polymer electrolytes, and strong stability, and has broad application prospects in the field of lithium-ion batteries. In addition, the preparation method of the present invention has the advantages of simple operation, short synthesis time, mild conditions, low cost, easy large-scale preparation, and convenient market promotion.

Description

Technical Field

[0001] The present invention belongs to the field of electrochemical technology, and in particular relates to a composite solid electrolyte and a preparation method and application thereof. Background Art

[0002] Lithium-ion batteries have the advantages of high discharge voltage, high energy density and environmental friendliness, and they occupy an important position in portable electronic devices including mobile phones, tablet computers, digital cameras, etc. The rapid development of electric vehicles, smart networks, aerospace and space technology has led to higher requirements for the various performance indicators of lithium-ion batteries. At present, commercial lithium-ion batteries still use organic liquid electrolytes or gel electrolytes. The organic electrolytes are flammable and explosive, posing a great safety hazard. At the same time, the incompatibility of organic electrolytes with high-energy-density electrode materials such as metallic lithium limits the improvement of battery energy density. Therefore, the fundamental way to solve the above problems is to replace organic electrolytes with solid electrolytes to develop solid-state batteries with high energy density, high safety and long cycle life.

[0003] In recent years, solid-state batteries have received widespread attention and attention from researchers at home and abroad. Compared with traditional liquid batteries, all-solid-state batteries have unique advantages such as high safety, high energy density and long cycle life. Therefore, solid-state batteries are expected to become the preferred energy storage material for future development. However, solid-state batteries also face some problems that need to be solved urgently, such as the use of inorganic solid electrolytes, which may cause short circuits due to lithium dendrite growth and poor mechanical compatibility with electrodes. As the core component of all-solid-state lithium batteries, solid electrolytes are key materials for achieving high energy density, high cycle stability and high safety performance of all-solid-state lithium batteries.

[0004] The existing technology has made various attempts to modify the types and structures of solid electrolytes, including adding plasticizers, cross-linking, grafting, optimizing the structure and concentration of lithium salts, and introducing inorganic fillers. Among them, adding inorganic fillers to polymer solid electrolytes to construct composite solid electrolytes is an effective strategy to comprehensively improve the various properties of solid electrolytes. However, existing solid electrolytes still have problems such as easy agglomeration of inorganic fillers and a large proportion of internal coupled lithium ion transport areas, resulting in poor performance. Moreover, the mechanical rigidity of the prepared composite solid electrolyte is low, making it difficult to inhibit the growth of lithium dendrites. There are many composite materials in nature that combine various superior properties, and enamel is one of them. It is both hard and has high damping properties, and can cope well with external impacts.

[0005] Therefore, in response to the above-mentioned problems in the field of composite solid electrolytes, there is an urgent need for a bionic composite solid electrolyte with high rigidity, high damping, simple experimental operation, convenience for actual production needs, and high mechanical properties. Summary of the Invention

[0006] To address at least some of the technical problems in the above-mentioned prior art, the present invention mimics the microstructure and composition of natural tooth enamel and utilizes the oxygen vacancies on the surface of the amorphous nanotube array and its orientation perpendicular to the electrode to increase the number and transmission channels of free lithium ions, reduce interfacial impedance, and increase lithium ion conductivity, thereby improving the mechanical rigidity and damping properties of the solid-state electrolyte, effectively inhibiting the growth of lithium dendrites, improving mechanical compatibility with the electrode, and enhancing the stability and electrochemical performance of the solid-state battery. Specifically, the present invention includes the following contents.

[0007] In a first aspect, the present invention provides a biomimetic composite solid electrolyte based on an amorphous nanotube array, which comprises an amorphous nanotube array and a polymer matrix, wherein the polymer matrix is ​​filled inside the nanotubes of the amorphous nanotube array.

[0008] In certain embodiments, according to the biomimetic composite solid electrolyte based on an amorphous nanotube array of the present invention, the nanotubes of the amorphous nanotube array are open at both ends, and the orientation of each nanotube is the same.

[0009] In certain embodiments, according to the biomimetic composite solid electrolyte based on amorphous nanotube arrays of the present invention, the characteristic peak in the XRD diffraction pattern of the amorphous nanotubes is a Bao peak.

[0010] In certain embodiments, the biomimetic composite solid electrolyte based on amorphous nanotube arrays according to the present invention further comprises a lithium salt.

[0011] In certain embodiments, according to the biomimetic composite solid electrolyte based on amorphous nanotube arrays of the present invention, the outer diameter of the nanotubes is 50-500 nm, and the height of the array is 2-100 μm.

[0012] In certain embodiments, according to the biomimetic composite solid electrolyte based on amorphous nanotube arrays of the present invention, at least the surface of the nanotubes has oxygen vacancies.

[0013] A second aspect of the present invention provides a method for preparing a biomimetic composite solid electrolyte based on an amorphous nanotube array, comprising the following steps:

[0014] (1) providing an amorphous nanotube array; and

[0015] (2) A step of filling the nanotubes of the amorphous nanotube array with a polymer matrix.

[0016] In certain embodiments, according to the method of the present invention, the amorphous nanotube array is prepared by an electrolytic etching method.

[0017] A third aspect of the present invention provides a solid-state lithium-ion battery comprising the biomimetic composite solid electrolyte based on the amorphous nanotube array according to the present invention.

[0018] In certain embodiments, the solid-state lithium-ion battery according to the present invention further comprises a positive electrode and a negative electrode, and the biomimetic composite solid-state electrolyte is located between the positive electrode and the negative electrode.

[0019] The fourth aspect of the present invention provides the use of the bionic composite solid electrolyte according to the present invention, the bionic composite solid electrolyte obtained by the preparation method according to the present invention, or the solid-state lithium-ion battery according to the present invention in electrical equipment.

[0020] The biomimetic composite solid electrolyte and its preparation method of the present invention have the following advantages:

[0021] First, the amorphous nanotube arrays of the present invention have a large number of positively charged oxygen vacancies on their surface, which imparts increased surface activity. These oxygen vacancies promote the dissociation of lithium salts in the polymer, increasing the number of free lithium ions and transport channels, and reducing interfacial impedance, thereby promoting lithium ion conduction.

[0022] Secondly, the polymer chains have a greater diffusion coefficient on the surface of the amorphous nanotubes, increasing the diffusion of free lithium ions. Furthermore, the amorphous nanotube arrays of the present invention have an orientation perpendicular to the positive and negative electrodes, providing a continuous and rapid lithium ion transport path within the polymer matrix. Furthermore, they effectively disrupt the crystallinity of the polymer, increasing the volume fraction of the amorphous phase and, consequently, improving lithium ion conductivity.

[0023] In addition, the bionic composite solid electrolyte of the present invention has a bionic structure that imitates dental enamel, which can improve the mechanical rigidity and damping properties of the solid electrolyte, effectively inhibit the growth of lithium dendrites, thereby significantly improving the mechanical compatibility with the electrode, and further improving the stability and electrochemical performance of the solid-state battery.

[0024] Finally, the preparation method of the present invention has the advantages of simple operation, short synthesis time, mild conditions, low cost, easy large-scale preparation, and convenient market promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the TEM image of the amorphous titanium oxide nanotubes in Example 1.

[0026] Figure 2 This is the XRD pattern of the amorphous titanium oxide nanotube array in Example 1.

[0027] Figure 3 This is the SEM image of the amorphous titanium oxide nanotube array in Example 1.

[0028] Figure 4This is the EDS analysis diagram of the amorphous titanium oxide nanotube elements in Example 1.

[0029] Figure 5 This is the XPS analysis chart of the titanium element in the amorphous titanium oxide nanotubes of Example 1.

[0030] Figure 6 These are the EPR test images of amorphous titanium oxide nanotubes and crystalline titanium oxide nanotubes in Example 1.

[0031] Figure 7 The thermogravimetric diagram of the biomimetic composite solid electrolyte derived from the amorphous nanotube array in Example 1 and the pure polyethylene oxide (PEO) solid electrolyte.

[0032] Figure 8 This is a mechanical comparison diagram of the biomimetic composite solid electrolyte derived from the amorphous nanotube array in Example 1 and other solid electrolytes.

[0033] Figure 9 This is the EIS graph of the biomimetic composite solid electrolyte derived from the amorphous nanotube array in Example 1.

[0034] Figure 10 This is the Li-Li cycle diagram of the biomimetic composite solid electrolyte derived from the amorphous nanotube array in Example 1.

[0035] Figure 11 This is an electrochemical test diagram of a button-type full battery assembled with a biomimetic composite solid electrolyte derived from an amorphous nanotube array and a LiFePO4 positive electrode in Example 1, and a specific capacity and coulombic efficiency cycle curve of the full battery at 60°C. DETAILED DESCRIPTION

[0036] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0037] It should be understood that the terms described in the present invention are only for describing particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges in the present invention, it should be understood that the upper and lower limits of the ranges and each intermediate value therebetween are specifically disclosed. Each smaller range between any stated value or intermediate value within a stated range and any other stated value or intermediate value within the stated range is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0038] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the invention belongs. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In the event of any conflict with any incorporated document, the content of this specification shall prevail.

[0039] Bionic composite solid electrolyte

[0040] One aspect of the present invention provides a biomimetic composite solid electrolyte based on an amorphous nanotube array, which includes an amorphous nanotube array and a polymer matrix and does not contain any fluid in the form of a solvent, wherein the polymer matrix is ​​filled inside the nanotubes of the amorphous nanotube array.

[0041] In the present invention, "amorphous" refers to a nanotube array that lacks a fixed crystalline structure. Instead, its atomic units, such as basic units, form a disordered, irregular structure without a long-range ordered structure. The amorphous structure is formed by rapid cooling of the solidified material used to prepare the nanotube array during the preparation process. In certain embodiments, "amorphous nanotubes" refers to a material having characteristic peaks in its XRD diffraction pattern that are characterized by a peak pattern of a bund, broad, or bun-shaped peak.

[0042] In the present invention, nanotubes include but are not limited to nanotubes made from metal oxides, wherein the metal oxides include but are not limited to titanium oxide, zirconium oxide, aluminum oxide, magnesium oxide, zinc oxide, copper oxide, tin oxide, etc. In a preferred embodiment, the nanotubes are titanium oxide nanotubes.

[0043] In a preferred embodiment, the nanotubes in the amorphous nanotube array are open at both ends, and the nanotubes have the same orientation. "Same orientation" means that the nanotubes in the array are arranged in parallel or substantially parallel.

[0044] In a preferred embodiment, the outer diameter of the nanotubes is 50-500 nm, preferably 60-400 nm, further preferably 70-300 nm, further preferably 80-200 nm, more preferably 90-180 nm, and even more preferably 100-150 nm, for example, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, and 150 nm. The height of the nanotube array is 2-100 μm, preferably 3-90 μm, further preferably 4-70 μm, and even more preferably 5-50 μm, for example, 5, 10, 15, 20, 25, 30, 35, 40, 45, and 50 μm.

[0045] In the present invention, at least the surface of the amorphous nanotube array has a large number of positively charged oxygen vacancies. These can interact with negatively charged ions, promoting the dissociation of lithium salts in the polymer, increasing the number of free lithium ions and the transport pathways, reducing interfacial impedance, and thus promoting lithium ion conduction. Furthermore, the amorphous nanotube array has an orientation perpendicular to the positive and negative electrodes in the solid-state battery, providing a continuous and rapid lithium ion transport path and increasing lithium ion conductivity.

[0046] In the present invention, the polymer matrix and its molecular weight are not particularly limited, and can be any polymer used for solid electrolytes, examples of which include but are not limited to at least one of polyethylene oxide, ethylene oxide-propylene oxide copolymer, polyethylene oxide, polyacrylonitrile, polymethacrylonitrile, polymethyl methacrylate, polyvinylidene fluoride, polypropylene oxide, polyvinylidene chloride, polyethylene carbonate, polytrimethylene carbonate, polypropylene carbonate and its derivatives, polyimide, polyurethane, polyacrylamide, polyvinyl acetate, polyvinyl pyrrolidone, polyethylene glycol diacrylate, polyphenylene sulfide, poly(p-phenylene oxide), polyetheretherketone, polyphthalamide, polypyrrole, polyaniline and polysulfone. In a preferred embodiment, the polymer matrix of the present invention is polyethylene oxide.

[0047] In the present invention, the biomimetic composite solid electrolyte further includes a lithium salt, which can be any lithium ion salt used for electrolytes, examples of which include but are not limited to at least one of lithium bis(trifluoromethanesulfonyl)imide, lithium chloride, lithium bromide, lithium iodide, lithium sulfide, lithium perchlorate, lithium tetrafluoroborate, lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium acetate, lithium trifluoromethanesulfonate, lithium trifluoromethanesulfonate, lithium cyanide, lithium bis(oxalatoborate), lithium nitrate, lithium bis(trifluoromethylsulfonyl)imide and lithium bis(oxalatoborate).

[0048] Preparation method

[0049] One aspect of the present invention provides a method for preparing a biomimetic composite solid electrolyte based on an amorphous nanotube array, which includes steps (1) and (2), which are described in detail below.

[0050] Step (1) of the present invention is a step of providing an amorphous nanotube array. The amorphous nanotube array can be prepared using any method known in the art, including but not limited to electrolytic etching (also known as "anodization"), template synthesis, hydrothermal synthesis, sol-gel, and electrochemical deposition. As an exemplary embodiment, the present invention uses an anodic oxidation method to prepare the amorphous nanotube array.

[0051] In a specific embodiment, the steps of preparing the amorphous nanotube array include:

[0052] (1') preparing an electrolyte solution of anhydrous ethylene glycol, ammonium fluoride, and hydrogen peroxide, immersing a titanium sheet in the electrolyte solution, setting a voltage for a first anodic oxidation, and obtaining an amorphous titanium oxide nanotube array;

[0053] (2') The amorphous titanium oxide nanotube array is subjected to heat treatment to obtain a peeled (separated) amorphous titanium oxide nanotube array, which is then immersed in an electrolyte and subjected to a second anodization to obtain an amorphous titanium oxide nanotube array with through holes.

[0054] In order to obtain an amorphous titanium oxide nanotube array and thus obtain a biomimetic composite solid electrolyte with excellent mechanical and electrochemical properties, the temperature of the anodic oxidation should not be too high or too low. If it is too high, the nanotube array will transform from an amorphous to a crystalline form, while if it is too low, the oxidation will be incomplete. In a preferred embodiment, the temperature of the anodic oxidation is 5-40°C, preferably room temperature, such as 20-40°C, and more preferably 20-35°C, such as 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35°C.

[0055] In the present invention, in order to obtain an amorphous titanium oxide nanotube array and thus obtain a biomimetic composite solid electrolyte with excellent mechanical and electrochemical properties, the heat treatment temperature should not be too high. In a preferred embodiment, the heat treatment temperature is 100-350°C, preferably 110-340°C, further preferably 120-330°C, more preferably 130-320°C, for example 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320°C.

[0056] In a preferred embodiment, step (1') of the present invention comprises: adding 200-800 mL, preferably 250-750 mL, further preferably 300-700 mL, for example 300, 350, 400, 450, 500, 550, 600, 650, 700 mL of anhydrous ethylene glycol, 0.05-5 wt%, preferably 0.1-4 wt%, for example 0.1 wt%, 0.5 wt%, 1.0 wt%, 1.5 wt%, 2.0wt%, 2.5wt%, 3.0wt%, 3.5wt%, 4.0wt% of ammonium fluoride, 0.5-10wt%, preferably 1-9wt%, also preferably 1-8wt%, for example 1.0wt%, 1.5wt%, 2.0wt%, 2.5wt%, 3.0wt%, 3.5wt%, 4.0wt%, 4.5wt%, 5.0wt%, 5.5wt%, 6.0wt%, 6.5wt%, 7.0wt% The titanium sheet is immersed in the electrolyte with hydrogen peroxide containing t%, 7.5wt%, and 8.0wt%, and the voltage is set to 40-100V, preferably 50-90V, such as 50, 55, 60, 65, 70, 75, 80, 85, and 90V. The first anodization is performed at room temperature for 0.5-6h, such as 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, and 6h to obtain Amorphous titanium oxide nanotube array; subsequently, the amorphous titanium oxide nanotube array is heat treated at 100-350 ° C for 0.5-6 hours, for example, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6 hours, immersed in an electrolyte, and subjected to a second anodization at room temperature for 0.5-6 hours, for example, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6 hours.

[0057] Step (2) of the present invention is a step of filling the nanotubes of the amorphous nanotube array with a polymer matrix. In a preferred embodiment, step (2) comprises immersing the amorphous titanium oxide nanotube array in a polymer electrolyte solution for 12-18 hours, removing it, and drying it. In order to obtain a composite solid electrolyte with adjustable thickness, the immersion / dropping and drying process can be repeated several times. For example, the polymer electrolyte is dropped onto the dried amorphous titanium oxide nanotube array, dried again, and the dropping and drying are repeated to obtain a composite solid electrolyte with a specific thickness.

[0058] In a specific embodiment, step (2) comprises soaking the amorphous titanium oxide nanotube array in the polymer electrolyte solution for 12-18 hours, for example, 12, 12.5, 13, 13.5, 14, 14.5, 15, 15.5, 16, 16.5, 17, 17.5, 18 hours, taking it out, drying it, and adding 20-80 μL, preferably 30-70 μL, for example, 30, 35, 40, 45, 50, 55, 60, 65, 70 μL The polymer electrolyte is dropped onto the dried amorphous titanium oxide nanotube array and dried again, and the dropping and drying steps are repeated 4-6 times, for example 4, 5, and 6 times, to obtain a composite solid electrolyte with a thickness of 2-100 μm (preferably 5-90 μm, also preferably 10-80 μm, further preferably 10-70 μm, more preferably 10-60 μm, more preferably 10-50 μm, for example 10, 15, 20, 25, 30, 35, 40, 45, 50 μm).

[0059] solid-state lithium-ion batteries

[0060] One aspect of the present invention provides a solid-state lithium-ion battery comprising the biomimetic composite solid-state electrolyte based on the amorphous nanotube array described in the present invention.

[0061] In a preferred embodiment, the solid-state lithium-ion battery of the present invention further comprises a positive electrode and a negative electrode, the biomimetic composite solid electrolyte is located between the positive electrode and the negative electrode, and the orientation of the nanotubes in the biomimetic composite solid electrolyte is perpendicular to the positive electrode and the negative electrode of the battery.

[0062] In the present invention, the materials used for the positive and negative electrodes are not particularly limited. For example, the positive electrode materials include but are not limited to lithium cobalt oxide (LCO), lithium manganese oxide (LMO), lithium iron phosphate (LFP), ternary materials (lithium nickel cobalt manganese oxide (NCM) and lithium nickel cobalt aluminum oxide (NCA). The negative electrode materials include but are not limited to carbon negative electrode materials, tin-based negative electrode materials, lithium transition metal nitride negative electrode materials, alloy negative electrode materials and nano-scale negative electrode materials.

[0063] The solid-state lithium-ion battery using the bionic composite solid-state electrolyte of the present invention can effectively inhibit the growth of lithium dendrites and improve the mechanical compatibility with the electrode, thereby improving the stability and electrochemical performance of the solid-state lithium-ion battery.

[0064] application

[0065] The biomimetic composite solid electrolyte or solid-state lithium-ion battery of the present invention can be used in various applications, such as solar panels, consumer electronic devices, vehicles, or power grids. Consumer electronic devices include, but are not limited to, display devices, MP3 players, smartphones, tablets, smartwatches, other wearable devices, or medical devices. Vehicles include, but are not limited to, hybrid electric buses, electric buses, hybrid electric vehicles, electric vehicles, electric bicycles, electric motorcycles, electric scooters, electric golf carts, trains, ships, airplanes, electric airplanes, helicopters, unmanned aerial vehicles, electric unmanned aerial vehicles, drones, other aircraft, space stations, space shuttles, satellites, unmanned spacecraft, other spacecraft, hybrid electric vehicles, and plug-in hybrid electric vehicles. Power grids include, but are not limited to, independent microgrids for residences, commercial buildings, and communities, as well as centralized power grids. Those skilled in the art will appreciate that the biomimetic composite solid electrolyte or solid-state lithium-ion battery of the present invention can also be used in energy storage devices for telecommunications systems, antenna towers, data centers, and uninterruptible power supplies.

[0066] Example 1

[0067] The preparation and characterization of the biomimetic composite solid electrolyte are shown below.

[0068] 1. Preparation Method

[0069] S1. Weigh 500 mL of anhydrous ethylene glycol, add 1 wt.% ammonium fluoride and 1 wt.% hydrogen peroxide to prepare an electrolyte, immerse a 95% pure titanium sheet (2.5×2.5 cm) in the electrolyte, set a voltage of 60 V, and perform anodization at room temperature for 6 h to obtain an amorphous titanium oxide nanotube array.

[0070] S2. Place the amorphous titanium oxide nanotube array in a tube furnace and heat treat it at 150°C for 2 h.

[0071] S3. Immerse the heat-treated amorphous titanium oxide nanotube array in an electrolyte and perform secondary anodization at a voltage of 60 V for 6 hours to obtain a through-hole amorphous titanium oxide nanotube array.

[0072] S4. Soak the amorphous titanium oxide nanotube array obtained in step S1 in a PEO polymer electrolyte solution for 12 hours, take it out and dry it naturally.

[0073] S5. Take 50 μL of PEO polymer electrolyte and drop it on the obtained dried amorphous titanium oxide nanotube array. After drying, add PEO polymer electrolyte solution again. Repeat 4 times to obtain a biomimetic composite solid electrolyte with a thickness of 55 μm.

[0074] 2. Characterization

[0075] The morphology and structure of the prepared biomimetic composite solid electrolyte were characterized. Figure 1 As shown, the diameter of the nanotube is 120 nm and the inner diameter is 80 nm. The phase structure of the nanotube was characterized by X-ray diffractometer (measurement conditions: scanning range 10°-80° (2θ), scanning rate set to 4°·min -1 ), Figure 2 The XRD spectrum results show that the nanotubes prepared in this embodiment have amorphous characteristic peaks. Figure 3 As shown, the nanotube array is uniformly arranged. Figure 4 and Figure 5 They are the EDS analysis chart of the amorphous nanotubes of Example 1 of the present invention and the XPS analysis chart of the titanium element. Figure 4 It can be seen that titanium and oxygen elements are evenly distributed. Figure 5 It can be seen that the titanium binding energy of amorphous nanotubes shifts toward the low binding energy direction. Figure 6 It can be seen that amorphous nanotubes have oxygen vacancies, while crystalline nanotubes do not.

[0076] Figure 7 The thermogravimetric diagrams of the bionic composite solid electrolyte derived from amorphous nanotube arrays and pure PEO solid electrolyte show that the composite solid electrolyte of the present invention has excellent thermal stability.

[0077] Figure 8 This is a mechanical diagram of a biomimetic composite solid electrolyte derived from an amorphous nanotube array. The results show that the rigidity of the composite solid electrolyte of the present invention is comparable to that of an inorganic solid electrolyte, and the damping properties are comparable to those of a polymer.

[0078] Figure 9 This is the electrochemical impedance spectroscopy (EIS) graph of the biomimetic composite solid electrolyte derived from amorphous nanotube arrays at room temperature. Figure 10 The Li-Li cycle diagram of the biomimetic composite solid electrolyte derived from amorphous nanotube arrays at 60°C shows that its ionic conductivity reaches 1.34×10 -4 S cm -1 , lithium-lithium cycle polarization voltage is 68mV.

[0079] Figure 11 This is the electrochemical test diagram of a button-type full battery assembled with a bionic composite solid electrolyte derived from an amorphous nanotube array and a LiFePO4 positive electrode. This is the specific capacity-Coulombic efficiency cycle curve of the full battery at 60°C. The results show that the solid-state lithium battery using lithium iron phosphate as the positive electrode can stably cycle 800 cycles at a current density of 1C.

[0080] The above electrochemical tests show that the biomimetic composite solid electrolyte derived from the amorphous nanotube array of the present invention has excellent electrochemical properties.

[0081] Example 2

[0082] The preparation and characterization of the biomimetic composite solid electrolyte are shown below.

[0083] 1. Preparation Method

[0084] S1. Weigh 500 mL of anhydrous ethylene glycol, add 1 wt.% ammonium fluoride and 1 wt.% hydrogen peroxide to prepare an electrolyte, immerse a 95% pure titanium sheet (2.5×2.5 cm) in the electrolyte, set a voltage of 90 V, and perform anodization at room temperature for 6 h to obtain an amorphous titanium oxide nanotube array.

[0085] S2. Place the amorphous titanium oxide nanotube array in a tube furnace and heat treat it at 150°C for 2 h.

[0086] S3. Immerse the heat-treated amorphous titanium oxide nanotube array in an electrolyte and perform secondary anodization at a voltage of 60 V for 6 hours to obtain a through-hole amorphous titanium oxide nanotube array.

[0087] S4. Soak the amorphous titanium oxide nanotube array obtained in step S1 in a PEO polymer electrolyte solution for 12 hours, take it out and dry it naturally.

[0088] S5. Then, 50 μL of PEO polymer electrolyte was dripped onto the obtained dried amorphous titanium oxide nanotube array. After drying, PEO polymer electrolyte solution was dripped again. This was repeated 4 times to obtain a biomimetic composite solid electrolyte with a thickness of 55 μm.

[0089] 2. Characterization

[0090] The prepared biomimetic composite solid electrolyte was electrochemically tested according to the test method of Example 1, and its ionic conductivity reached 0.46×10 -4 S cm -1 .

[0091] Example 3

[0092] The preparation and characterization of the biomimetic composite solid electrolyte are shown below.

[0093] 1. Preparation Method

[0094] S1. Weigh 500 mL of anhydrous ethylene glycol, add 1 wt.% ammonium fluoride and 1 wt.% hydrogen peroxide to prepare an electrolyte, immerse a 95% pure titanium sheet (2.5×2.5 cm) in the electrolyte, set a voltage of 50 V, and perform anodization at room temperature for 6 h to obtain an amorphous titanium oxide nanotube array.

[0095] S2. Place the amorphous titanium oxide nanotube array in a tube furnace and heat treat it at 150°C for 2 h.

[0096] S3. Immerse the heat-treated amorphous titanium oxide nanotube array in an electrolyte and perform secondary anodization at a voltage of 60 V for 6 hours to obtain a through-hole amorphous titanium oxide nanotube array.

[0097] S4. Soak the amorphous titanium oxide nanotube array obtained in step S1 in a PEO polymer electrolyte solution for 12 hours, take it out and dry it naturally.

[0098] S5. Then, 50 μL of PEO polymer electrolyte was dripped onto the obtained dried amorphous titanium oxide nanotube array. After drying, PEO polymer electrolyte solution was dripped again. This was repeated 4 times to obtain a biomimetic composite solid electrolyte with a thickness of 55 μm.

[0099] 2. Characterization

[0100] The prepared biomimetic composite solid electrolyte derived from amorphous nanotube arrays was electrochemically tested according to the test method of Example 1, and the ionic conductivity was measured to be 0.98×10 -4 S cm -1 .

[0101] Comparative Example 1

[0102] 1. Preparation Method

[0103] K1. Dissolve 1 g of polyethylene oxide and 0.7 g of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in 6 ml of acetonitrile solvent, and heat and stir to obtain a PEO polymer electrolyte solution.

[0104] K2. Pour the solution onto release paper and then place it in a vacuum oven to dry to obtain a composite solid electrolyte.

[0105] 2. Characterization

[0106] The prepared solid electrolyte was electrochemically tested according to the test method of Example 1, and its ionic conductivity reached 0.24×10 -4 S cm -1 The lithium-lithium cycle polarization voltage is 150mV, and the capacity of the solid-state lithium battery using lithium iron phosphate as the positive electrode at a current density of 1C is 50mAh·g -1 It can be seen that the electrochemical performance of pure PEO solid electrolyte is poor and it is difficult to meet application needs.

[0107] Comparative Example 2

[0108] This comparative example illustrates the preparation of the crystalline nanotube-derived solid electrolyte described in Example 1. The method differs from the amorphous nanotube preparation method in Example 1 in that, after the amorphous nanotubes are prepared in S2, they are heat-treated at 400°C in air to obtain crystalline nanotubes. The remaining steps are the same as in Example 1.

[0109] The results are as follows Figure 8 As shown in the results, the performance of solid electrolytes derived from crystalline nanotubes in suppressing dendrites is lower than that of solid electrolytes derived from amorphous nanotubes. The rigidity and damping properties of solid electrolytes derived from crystalline nanotubes are also lower than those of solid electrolytes derived from amorphous nanotubes. Their lower mechanical compatibility limits their further applications. Figure 6 It can be seen that amorphous nanotubes have oxygen vacancies, while crystalline nanotubes do not. This makes crystalline nanotubes have poor electrochemical performance without surface modification, further limiting their application.

[0110] In summary, the biomimetic composite solid electrolyte derived from the amorphous nanotube array of the present invention has good interface stability and excellent electrochemical performance.

[0111] Finally, it should be noted that the above embodiments are intended only to illustrate the technical solutions of the present invention, and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may be modified or some of the technical features thereof may be replaced with equivalents. Such modifications or replacements do not deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for preparing a biomimetic composite solid electrolyte based on an amorphous nanotube array, characterized in that: The biomimetic composite solid electrolyte comprises an amorphous nanotube array and a polymer matrix, wherein the polymer matrix is ​​filled inside the nanotubes of the amorphous nanotube array, and at least the surface of the nanotubes has oxygen vacancies; The method comprises: (1) providing an amorphous titanium oxide nanotube array, comprising preparing an electrolyte solution with anhydrous ethylene glycol, ammonium fluoride, and hydrogen peroxide, immersing a titanium sheet in the electrolyte solution, setting a voltage for a first anodization to obtain an amorphous titanium oxide nanotube array, heat-treating the amorphous titanium oxide nanotube array to obtain a stripped amorphous titanium oxide nanotube array, and then immersing the amorphous titanium oxide nanotube array in the electrolyte solution for a second anodization to obtain an amorphous titanium oxide nanotube array having through holes, wherein the temperatures for the first anodization and the second anodization are 20-40° C., the temperature for the heat treatment is 120-200° C., and the time is 0.5-6 hours; (2) Filling the nanotubes of the amorphous titanium oxide nanotube array with a polymer matrix, comprising immersing the amorphous titanium oxide nanotube array in a polymer electrolyte solution for 12-18 hours, removing the amorphous titanium oxide nanotube array, drying the amorphous titanium oxide nanotube array, dripping the polymer electrolyte onto the dried amorphous titanium oxide nanotube array, drying the amorphous titanium oxide nanotube array, and repeating the dripping and drying process several times to obtain a composite solid electrolyte having a thickness of 2-100 μm.

2. The method for preparing a biomimetic composite solid electrolyte based on an amorphous nanotube array according to claim 1, characterized in that: Both ends of the nanotubes in the amorphous nanotube array are open, and the orientations of the nanotubes are the same.

3. The method for preparing a biomimetic composite solid electrolyte based on an amorphous nanotube array according to claim 1, characterized in that: The characteristic peaks in the XRD diffraction pattern of the amorphous nanotubes are envelope peaks or approximately envelope peaks.

4. The method for preparing a biomimetic composite solid electrolyte based on an amorphous nanotube array according to claim 1, characterized in that: The biomimetic composite solid electrolyte further includes a lithium salt.

5. The method for preparing a biomimetic composite solid electrolyte based on an amorphous nanotube array according to claim 1, wherein: The outer diameter of the nanotubes is 50-500 nm, and the height of the array is 2-100 μm.

6. A biomimetic composite solid electrolyte based on an amorphous nanotube array, characterized in that: It is prepared by the method according to any one of claims 1 to 5.

7. A solid-state lithium-ion battery, characterized in that: A biomimetic composite solid electrolyte based on an amorphous nanotube array according to claim 6, and A positive electrode and a negative electrode, and the bionic composite solid electrolyte is located between the positive electrode and the negative electrode.

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