Mixed ionic-electronic conductor ceramic and solid-state electrolyte, preparation methods therefor, and battery

Abstract

A mixed ionic-electronic conductor ceramic, comprising Ag-modified LLZTO ceramic. Further provided is a preparation method for the mixed ionic-electronic conductor ceramic, comprising the following steps: adding LLZTO ceramic to a solution containing a soluble silver salt and a reducing reagent to obtain silver oxide, and then reacting the silver oxide under the action of the reducing reagent to prepare the Ag-modified LLZTO ceramic. Further provided is a composite solid-state electrolyte, comprising the mixed ionic-electronic conductor ceramic, a lithium salt and a polymer. Further provided are a battery electrode material, comprising the mixed ionic-electronic conductor ceramic; and a battery, comprising the mixed ionic-electronic conductor ceramic or the solid-state electrolyte. When being used for electrode materials, said modified ceramic can achieve the effects of transporting both electrons and ions, thereby improving the dynamics of electrodes and achieving a good prospect of application in the field of batteries.

Description

Ionic electron mixed conductor ceramic, solid electrolyte, preparation method and battery Technical Field

[0001] The present invention relates to battery technology, in particular to ion-electron mixed conductor ceramics, solid electrolytes, preparation methods and batteries. Background Art

[0002] Compared with lead-acid batteries, lithium-ion batteries (LIBs) have the advantages of low self-discharge, no memory effect, high energy density, and long cycle life. They are widely used in many fields such as consumer electronics, energy storage, and new energy. With the introduction of the "carbon peak and carbon neutrality" dual carbon policy, the new energy field has entered a new stage of development. Electric vehicles (EVs) are in urgent need of batteries with higher safety and longer endurance, so lithium-ion batteries (LIBs) are developing towards high energy density, long life and greater safety. However, the capacity of traditional graphite negative electrodes is currently close to the theoretical limit, which limits the further improvement of the energy density of lithium batteries. Lithium metal and NCM811 have a charge capacity of 3860 mA·h·g –1 and more than 200mA·h·g –1 Due to their high theoretical capacity, they are considered one of the most promising negative and positive electrode materials for achieving high energy density. However, liquid lithium-ion batteries prepared with organic liquid electrolytes have many disadvantages, such as severe interfacial reactions and poor safety, which limit their practical application. For example, lithium dendrite growth can lead to battery short circuits, thermal runaway, and even explosion, and severe interfacial side reactions can lead to rapid capacity decay. Solid-state lithium-ion batteries (ASSLBs), which theoretically have high energy density and safety, are the most promising alternatives to liquid lithium-ion batteries.

[0003] Solid polymer electrolytes (SPEs) have the advantages of high elasticity and plasticity, good electrode affinity, and easy preparation. They are one of the most studied solid electrolytes. However, many problems such as poor mechanical properties and low ionic conductivity limit their practical use. For example, polymers such as polyethylene oxide (PEO) have a low dielectric constant and cannot promote the dissociation of lithium salt anion and cation pairs in the electrolyte, resulting in low room temperature ionic conductivity, which cannot meet the needs of daily use. At the same time, PEO has a low oxidation resistance window and cannot match high-voltage positive electrodes represented by NCM811. Solid electrolytes based on polyvinylidene fluoride (PVDF) have higher oxidation resistance and thermal stability, which makes them have greater practical application prospects. However, PVDF-based solid electrolytes still face problems such as low mechanical strength, low dielectric constant, insufficient ionic conductivity and ion migration number, resulting in poor battery rate performance and poor cycle life.

[0004] It should be noted that the information disclosed in the above background technology section is only used to understand the background of this application, and therefore may include information that does not constitute prior art known to ordinary technicians in this field.

[0005] Summary of the Invention

[0006] The main purpose of the present invention is to overcome the defects in the above-mentioned background technology and provide an ionic-electronic mixed conductor ceramic, a solid electrolyte, a preparation method and a battery.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] An ionic-electronic mixed conductor ceramic comprises Ag-modified LLZTO ceramic.

[0009] Furthermore, the LLZTO is Li 6.5 La3Zr 1.5 Ta 0.5 O 12 or Li7La3Zr2O 12 or its doped derivative ceramics.

[0010] A method for preparing an ionic-electronic mixed conductor ceramic comprises the following steps:

[0011] LLZTO ceramics are added to a solution containing a soluble silver salt and a reducing agent to obtain silver oxide;

[0012] The silver oxide reacts under the action of the reducing agent to prepare Ag-modified LLZTO ceramics.

[0013] Furthermore, the soluble silver salt is one of AgNO3, AgClO3 and AgClO4.

[0014] Furthermore, the reducing agent is one of ethanol, sulfurous acid, sodium sulfite, and hydrogen peroxide.

[0015] A composite solid electrolyte comprises the ionic-electronic mixed conductor ceramic, lithium salt and polymer.

[0016] Furthermore, the lithium salt is lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethylsulfonyl)imide, lithium hexafluorophosphate or lithium tetrafluoroborate. The polymer is polyethylene oxide (PEO), polyvinylidene fluoride (PVDF) or polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP).

[0017] A method for preparing a solid electrolyte comprises uniformly mixing the polymer, the lithium salt and the ion-electron mixed conductor ceramic in a predetermined proportion to prepare the solid electrolyte.

[0018] A battery electrode material comprises the ion-electron mixed conductor ceramic.

[0019] A battery comprises the ionic-electronic mixed conductor ceramic or the solid electrolyte.

[0020] The present invention has the following beneficial effects:

[0021] The present invention provides a Ag-modified LLZTO (LLZTO@Ag) ionic-electronic mixed conductor ceramic. This LLZTO@Ag composite ceramic exhibits both ionic and electronic conductivity. The composite solid electrolyte formed from this modified ceramic and polyvinylidene fluoride exhibits high dielectric constant, high ionic conductivity, and high ion transference number. When assembled with a lithium metal anode and an NCM811 cathode, the resulting battery exhibits excellent cycling stability at room temperature and maintains a high capacity after multiple cycles. This modified ceramic, when used as an electrode material, can simultaneously transport electrons and ions, improving electrode kinetics and promising application prospects in the battery field.

[0022] The present invention provides a method for preparing Ag-modified LLZTO (LLZTO@Ag) ionic and electronic mixed conductor ceramics. The method involves reacting silver ions with residual alkali on the LLZTO surface to form silver oxide, which is then reduced to elemental silver metal in the presence of a reducing agent. The solvent is then dried to yield LLZTO@Ag ceramic particles. The preparation method provided by the present invention is simple, operates under mild reaction conditions, is low-cost, and possesses strong adaptability and universality. The resulting LLZTO@Ag ceramic can be used to prepare composite solid-state electrolytes to improve their ionic conductivity and mechanical strength.

[0023] The composite solid electrolyte provided in this application has a high dielectric constant, exhibits high lithium salt dissociation degree, high ionic conductivity and ion migration number, can be well matched with the lithium metal negative electrode and NCM811 positive electrode, has good rate performance and cycle stability at large current, and has great application value.

[0024] Other beneficial effects of the embodiments of the present invention will be further described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 shows the preparation of Ag-modified Li in Example 1 6.5 La3Zr 1.5 Ta 0.5 O 12 Chemical reaction equations in the (LLZTO@Ag) ion-electron mixed conductor ceramic process;

[0026] FIG2 is an XRD test phase structure diagram of the LLZTO@Ag material prepared in Example 1;

[0027] FIG3 is the SEM morphology and element distribution of the LLZTO@Ag material prepared in Example 1;

[0028] FIG4 is a surface and cross-sectional SEM image of the composite solid electrolyte prepared in Example 2;

[0029] FIG5 is a surface SEM image of the PVL solid electrolyte membrane prepared in Comparative Example 1;

[0030] Figure 6 is an optical photograph (a) of the PVLA solid electrolyte membrane prepared in Example 2 and an optical photograph (b) of the PVL solid electrolyte prepared in Comparative Example 1;

[0031] FIG7 is a tensile test diagram of the solid electrolytes prepared in Comparative Example 1 and Example 2;

[0032] FIG8 is a dielectric constant test graph of the solid electrolytes prepared in Comparative Example 1 and Example 2;

[0033] FIG9 shows the ionic conductivity of the solid electrolytes prepared in Comparative Example 1 and Example 2;

[0034] FIG10 is a graph showing the ion migration number of the solid electrolytes prepared in Comparative Example 1 and Example 2;

[0035] FIG11 is a rate performance test curve of a full cell based on a PVLA and PVL composite solid electrolyte membrane prepared in Example 3;

[0036] FIG12 is a cycle performance test curve of a full battery based on a PVLA and PVL composite solid electrolyte membrane prepared in Example 3;

[0037] FIG13 is a long cycle test curve of a lithium-lithium symmetrical battery based on a PVLA and PVL composite solid electrolyte membrane prepared in Example 3. DETAILED DESCRIPTION

[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0040] The embodiment of the present invention provides an ionic and electronic mixed conductor ceramic, including Ag-modified LLZTO ceramic (LLZTO@Ag). The LLZTO is Li 6.5 La3Zr 1.5 Ta 0.5 O 12 、Li7La3Zr2O 12 In the present invention, the ionic and electronic mixed conductor ceramics only need to contain an effective amount of Ag. In some embodiments, the mass ratio of Ag to LLZTO is less than 1.

[0041] In one embodiment, an Ag-modified Li 6.5 La3Zr 1.5 Ta 0.5 O 12 The phase structure and morphology of ionic and electronic mixed conductor ceramics are shown in Figures 2 and 3.

[0042] The present invention also provides a method for preparing an ionic-electronic mixed conductor ceramic, comprising the following steps:

[0043] LLZTO ceramics are added to a solution containing a soluble silver salt and a reducing agent to obtain silver oxide;

[0044] The silver oxide reacts under the action of the reducing agent to prepare Ag-modified LLZTO ceramics.

[0045] In some embodiments, the molar ratio of silver ions to LLZTO in the silver salt is greater than 2, and the molar ratio of the number of electrons that can participate in the redox reaction of the reducing agent to the silver ions is greater than 1. 6.5 La3Zr 1.5 Ta 0.5 O 12 The preparation method of ionic electron mixed conductor ceramics comprises the following steps:

[0046] Take soluble silver salt and add it to ethanol solution to dissolve it. 6.5 La3Zr 1.5 Ta 0.5 O 12 Add it to the above solution to generate an in-situ reaction of Ag metal-modified LLZTO ceramic particle suspension, and dry the solution to obtain LLZTO@Ag particles.

[0047] Among them, silver ions are used to react with residual alkali on the surface of LLZTO to generate silver oxide, which is further reduced to silver metal in the presence of a reducing agent, and the solvent is dried to obtain LLZTO@Ag ceramic particles.

[0048] In some embodiments, the silver salt is selected from one of AgNO 3 , AgClO 3 and AgClO 4 .

[0049] In some embodiments, the reducing agent is selected from ethanol, sulfurous acid, sodium sulfite, and hydrogen peroxide.

[0050] A solid electrolyte is prepared from raw materials including the LLZTO@Ag ceramic, lithium salt and polymer.

[0051] In some embodiments, the lithium salt is selected from lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethylsulfonyl)imide, lithium hexafluorophosphate, and lithium tetrafluoroborate.

[0052] In some embodiments, the polymer is selected from one of polyoxyethylene (PEO), polyvinylidene fluoride (PVDF), and polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP).

[0053] In some embodiments, the method for preparing the solid electrolyte comprises the following steps:

[0054] The polymer, the lithium salt and the modified ceramic are mixed evenly in a certain proportion to prepare a solid electrolyte.

[0055] A battery comprises the above-mentioned Ag-modified LLZTO (LLZTO@Ag) ion-electronic mixed conductor ceramic, or the above-mentioned solid electrolyte.

[0056] In some embodiments, the battery is a lithium battery.

[0057] In one example, LLZTO is preferably Li 6.5 La3Zr 1.5 Ta 0.5 O 12 Ag metal-modified LLZTO ceramic particles are generated by in-situ reaction in an ethanol solution of silver nitrate, so that the formed LLZTO@Ag has both ionic conductivity and electronic conductivity.

[0058] The composite solid electrolyte formed from this modified ceramic and polyvinylidene fluoride exhibits high dielectric constant, high ionic conductivity, and high ion transference number. When paired with a lithium metal anode and an NCM811 cathode, the resulting battery exhibits excellent cycling stability at room temperature and maintains a high capacity after multiple cycles. The modified ceramic, when used in electrode materials, can simultaneously transport both electrons and ions, improving electrode kinetics and holding great promise for battery applications.

[0059] The following describes the method in combination with specific embodiments.

[0060] Example 1

[0061] This embodiment provides a Ag-modified Li 6.5 La3Zr 1.5 Ta 0.5 O 12 (LLZTO@Ag) ionic and electronic mixed conductor ceramics were prepared according to the following steps:

[0062] Step S1, adding 150 mg of AgNO3 into ethanol and completely dissolving it to obtain an ethanol solution of silver nitrate.

[0063] Step S2, take 200 mg Li 6.5 La3Zr 1.5 Ta 0.5 O 12 Add to the silver nitrate ethanol solution in S1 and stir for 12 hours to fully react.

[0064] Step S3, the suspension in S2 is allowed to stand for 2 hours, the supernatant is removed by suction, ethanol is added and stirred for 1 hour for washing, the suspension is allowed to stand for 2 hours, the supernatant is removed by suction, and a precipitate is obtained.

[0065] Step S4, drying the precipitate in step S3 in a blast oven at 80°C for 12 hours to obtain Ag-modified Li 6.5 La3Zr 1.5 Ta 0.5 O 12 (LLZTO@Ag) ionic and electronic mixed conductor ceramics.

[0066] See Figure 1, which shows the preparation of Ag-modified Li 6.5 La3Zr 1.5 Ta 0.5 O 12 The chemical reaction equations during the preparation and storage of the (LLZTO@Ag) ion-electron mixed conductor ceramic are shown. Residual alkali inevitably forms on the surface of LLZTO during its preparation and storage (Equation 1). Silver ions react with the residual alkali on the LLZTO surface to form silver oxide (Equation 2). The silver oxide is further reduced to elemental silver metal in the presence of a reducing agent (Equation 3). The solvent is then dried to yield the LLZTO@Ag ceramic particles.

[0067] Figure 2 shows the X-ray diffraction analysis (XRD) test phase structure diagram of the LLZTO@Ag material prepared in Example 1. It can be seen that the prepared material has two diffraction peaks, LLZTO and Ag, that is, there are two phases, LLZTO and Ag.

[0068] Figure 3 shows the scanning electron microscope (SEM) morphology of the LLZTO@Ag material prepared in Example 1. It can be seen that the morphology distribution of the two phases of LLZTO and Ag is that small Ag particles are dispersed on the surface of large LLZTO particles.

[0069] Example 2

[0070] This embodiment provides a high dielectric composite solid electrolyte (PVLA solid electrolyte), which is prepared according to the following steps:

[0071] Step S1: First, under an inert atmosphere, weigh 267 mg of LiFSI (lithium bis(fluorosulfonyl)imide) and place it in a stirring bottle. Add 15 mL of DMF (N,N-dimethylformamide) and 400 mg of PVDF (polyvinylidene fluoride) and stir on a small stirrer. Stir at room temperature for more than 2 hours until LiFSI and PVDF are completely dissolved to obtain a uniform transparent solution.

[0072] Step S2: 200 mg of the LLZTO@Ag obtained in Example 1 was added to the transparent solution obtained in Step S1, and stirred at room temperature for more than 6 hours to obtain a uniform black solution.

[0073] Step S3: Pour the solution obtained in step S2 into a glass culture dish, place it in a 55°C forced air oven and dry it for 23 hours to remove excess solvent DMF to obtain a PVLA composite solid electrolyte membrane, punch it into a suitable size, and store it in an inert atmosphere for drying before use.

[0074] FIG4 shows the surface and cross-sectional SEM images of the composite solid electrolyte prepared in Example 2. It can be seen that the surface of the composite solid electrolyte prepared in Example 2 of the present application is dense, the ceramic particles are evenly distributed, and the thickness is about 80 μm.

[0075] Comparative Example 1

[0076] A solid electrolyte is provided, and the preparation process is the same as step S1 of Example 2, except that in step S2, 200 mg of untreated Li 6.5 La3Zr 1.5 Ta 0.5 O 12 (LLZTO) was added to the transparent solution obtained in step S1, and after stirring for 6 h, the resulting solution was poured into a glass container and placed in a 55°C forced air oven to dry for 23 h to remove excess DMF solvent to obtain a PVL composite solid electrolyte membrane, which was punched into a suitable size and stored dry in an inert atmosphere until use.

[0077] Figure 5 shows a surface SEM image of the PVL composite solid electrolyte membrane prepared in Comparative Example 1. It can be seen that the composite solid electrolyte prepared in Comparative Example 1 of the present application has a rough surface, large pores, and uneven distribution of ceramic particles.

[0078] Figure 6 (a) shows an optical photograph of the PVLA composite solid electrolyte in Example 2, and (b) shows an optical photograph of the PVL composite solid electrolyte membrane prepared in Comparative Example 1. The PVL solid electrolyte membrane in Comparative Example 1 is brownish yellow, while the PVLA solid electrolyte obtained in Example 2 of the present application is black and the electrolyte is flat and dense.

[0079] Figure 7 shows the tensile curves of the PVL composite solid electrolyte membrane prepared in Example 1 and the PVLA composite solid electrolyte membrane modified in Example 1. It can be seen that compared with the PVL solid electrolyte membrane (3.1 MPa), the PVLA solid electrolyte membrane exhibits higher tensile strength (3.7 MPa).

[0080] Referring to FIG8 , the dielectric constant of the solid electrolytes prepared in Example 2 and Comparative Example 1 was tested. The experimental results show that after adding 50 wt% of the ionic-electronic mixed conductor ceramic LLZTO@Ag, the dielectric constant of the PVLA composite electrolyte is greatly improved, and the relative dielectric constant is 47 at a frequency of 10 Hz, which is much higher than that of the PVL composite solid electrolyte (15) prepared in Comparative Example 1.

[0081] FIG9 shows the ionic conductivity of the PVL-based solid electrolyte membrane of Comparative Example 1 and the PVLA solid electrolyte membrane of Example 2. It can be found that due to the significant increase in the dielectric constant, the dissociation degree of the lithium salt in the PVLA composite solid electrolyte increases, showing a 9.05×10 -4 S / cm, which is much higher than the 6.11×10 -4 Room temperature ionic conductivity of S / cm.

[0082] Referring to Figure 10 , ion transference number tests were conducted on the solid electrolytes prepared in Comparative Example 1 and Example 2. It was found that due to the significant increase in the dielectric constant, the degree of dissociation of the lithium salt in the PVLA composite solid electrolyte increased, resulting in a lithium ion transference number of 0.58, significantly higher than the 0.31 of the PVL-based solid electrolyte in Comparative Example 1.

[0083] Example 3

[0084] This embodiment provides an assembled full battery, which is assembled according to the following steps:

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

[0086] Step S2, preparing the positive electrode: coating the positive electrode slurry obtained in step S1 on aluminum foil, drying at 80°C for more than 6 hours, cutting into appropriate sizes to obtain NCM811 positive electrodes, and placing in a vacuum oven for drying and storage.

[0087] Step S3, preparing a composite solid electrolyte.

[0088] In step S4, according to the full battery assembly process, the NCM811 positive electrode prepared in step S2, the PVLA composite solid electrolyte membrane prepared in Example 2, the PVL composite solid electrolyte membrane prepared in Comparative Example 1 and lithium metal are assembled into a full battery.

[0089] Step S5, according to the symmetrical battery assembly process, the PVLA composite solid electrolyte membrane prepared in Example 2 and the PVL composite solid electrolyte membrane prepared in Comparative Example 1 are sandwiched between two layers of lithium metal to assemble into a lithium-lithium symmetrical battery.

[0090] Following the full-cell assembly process, this example fabricated a full cell based on PVLA and PVL composite solid electrolyte membranes. Figure 11 shows the rate performance test curves for the two cells. As can be seen, the full cell assembled with PVLA, an NCM811 cathode, and a lithium metal anode still achieved a capacity of 103 mAh / g at a current density of 10C at room temperature, exceeding the 54 mAh / g capacity of PVL.

[0091] Figure 12 shows the cycle performance test curve of the full battery based on PVLA and PVL composite solid electrolyte membrane. The results show that the full battery assembled after PVLA is matched with NCM811 positive electrode and lithium metal negative electrode can stably cycle 300 cycles at a current density of 3C at room temperature, showing higher discharge capacity and stability than PVL.

[0092] According to the assembly process of symmetrical cells, this embodiment prepared a lithium-lithium symmetrical cell based on PVLA and PVL composite solid electrolyte membranes. Figure 13 shows the lithium-lithium symmetric test curves of the two batteries. The results show that the lithium-lithium symmetrical cell formed by PVLA matching lithium metal assembly has a high conductivity at 1 mA / cm 2 Current density, 1mAh / cm 2It can cycle stably for 1000 hours at the deposited capacity, showing lower polarization voltage and longer cycle life than PVL.

[0093] Example 4

[0094] This embodiment provides an Ag-modified Li7La3Zr2O 12 (LLZO@Ag) ionic and electronic mixed conductor ceramics are prepared according to the following steps:

[0095] Step S1, adding 150 mg of AgNO3 into ethanol and completely dissolving it to obtain an ethanol solution of silver nitrate.

[0096] Step S2, take 200mg Li7La3Zr2O 12 Add to the silver nitrate ethanol solution in S1 and stir for 12 hours to fully react.

[0097] In step S3, the suspension in step S2 is allowed to stand for 2 hours, the supernatant is removed by suction, ethanol is added and stirred for 1 hour for washing, the suspension is allowed to stand for 2 hours, and the supernatant is removed by suction to obtain a precipitate.

[0098] Step S4, drying the precipitate in step S3 in a forced air oven at 80°C for 12 hours to obtain Ag-modified Li7La3Zr2O 12 (LLZO@Ag) ionic and electronic mixed conductor ceramics.

[0099] Example 5

[0100] This embodiment provides an assembled full battery, which is assembled according to the following steps:

[0101] Step S1, prepare the positive electrode slurry: First, weigh 100 mg of PVDF (binder) and place it in a stirring bottle. Add 1 mL of NMP (N-methylpyrrolidone) and stir on a small stirrer for 1 hour until the PVDF is completely dissolved. Then, add 100 mg of SuperP (conductive carbon black) and 1 mL of NMP and stir at room temperature for 1 hour. Then, add 800 mg of NCM811 active material and 1.5 mL of NMP and stir at room temperature for at least 6 hours.

[0102] Step S2, preparing the positive electrode: coating the positive electrode slurry obtained in step S1 on aluminum foil, drying at 80°C for more than 6 hours, cutting into appropriate sizes to obtain NCM811 positive electrodes, and placing in a vacuum oven for drying and storage.

[0103] Step S3, preparing PVDF-LLZO@Ag composite solid electrolyte:

[0104] S31. First, weigh 267 mg of LiFSI under an inert atmosphere, place it in a stirring bottle, add 15 mL of DMF and 400 mg of PVDF, and stir on a small stirrer. Stir at room temperature for more than 2 hours until LiFSI and PVDF are completely dissolved to obtain a uniform transparent solution.

[0105] S32. Add 200 mg of LLZO@Ag to the solution obtained in step S31, and stir at room temperature for more than 24 hours to obtain a uniform black solution.

[0106] S33. Pour the solution obtained in step S32 into a glass culture dish, place it in a 55°C forced air oven and dry it for 23 hours to remove excess solvent DMF to obtain a PVDF-LLZO@Ag composite solid electrolyte membrane, punch it into a suitable size, and store it in an inert atmosphere for drying and use.

[0107] In step S4, according to the battery assembly process, the NCM811 positive electrode prepared in step S2, the PVDF-LLZO@Ag-based solid electrolyte membrane prepared in step S3 and lithium metal are assembled into a full battery.

[0108] Example 6

[0109] This embodiment provides an assembled full battery, which is assembled according to the following steps:

[0110] Step S1, prepare the positive electrode slurry: First, weigh 100 mg of PVDF (binder) and place it in a stirring bottle. Add 1 mL of NMP (N-methylpyrrolidone) and stir on a small stirrer for 1 hour until the PVDF is completely dissolved. Then, add 100 mg of SuperP (conductive carbon black) and 1 mL of NMP and stir at room temperature for 1 hour. Then, add 800 mg of NCM811 active material and 1.5 mL of NMP and stir at room temperature for at least 6 hours.

[0111] Step S2, preparing the positive electrode: coating the positive electrode slurry obtained in step S1 on aluminum foil, drying at 80°C for more than 6 hours, cutting into appropriate sizes to obtain NCM811 positive electrodes, and placing in a vacuum oven for drying and storage.

[0112] Step S3, preparing a PEO-LLZTO@Ag composite solid electrolyte:

[0113] S31. First, under an inert atmosphere, weigh 267 mg of LiTFSI and place it in a stirring bottle. Add 15 mL of acetonitrile and 400 mg of PEO, and stir on a small stirrer. Stir at room temperature for more than 2 h until LiTFSI and PEO are completely dissolved to obtain a uniform transparent solution.

[0114] S32. Add 200 mg of LLZTO@Ag to the solution obtained in step S31 and stir at room temperature for more than 24 h to obtain a uniform black solution.

[0115] S33. Pour the solution obtained in step S32 into a glass culture dish, place it in a 60°C forced air oven and dry it for 24 hours to remove the solvent acetonitrile to obtain a PEO-LLZTO@Ag composite solid electrolyte membrane, punch it into a suitable size, and store it in an inert atmosphere for drying and use.

[0116] In step S4, according to the battery assembly process, the NCM811 positive electrode prepared in step S2, the PEO-LLZTO@Ag-based solid electrolyte membrane prepared in step S3 and lithium metal are assembled into a full battery.

[0117] Example 7

[0118] This embodiment provides an assembled full battery, which is assembled according to the following steps:

[0119] Step S1, prepare the positive electrode slurry: First, weigh 100 mg of PVDF (binder) and place it in a stirring bottle. Add 1 mL of NMP (N-methylpyrrolidone) and stir on a small stirrer for 1 hour until the PVDF is completely dissolved. Then, add 100 mg of SuperP (conductive carbon black) and 1 mL of NMP and stir at room temperature for 1 hour. Then, add 800 mg of NCM811 active material and 1.5 mL of NMP and stir at room temperature for at least 6 hours.

[0120] Step S2, preparing the positive electrode: coating the positive electrode slurry obtained in step S1 on aluminum foil, drying at 80°C for more than 6 hours, cutting into appropriate sizes to obtain NCM811 positive electrodes, and placing in a vacuum oven for drying and storage.

[0121] Step S3, preparing PVDF-HFP-LLZTO@Ag composite solid electrolyte:

[0122] S31. First, weigh 267 mg of LiFSI under an inert atmosphere, place it in a stirring bottle, add 15 mL of DMF, and stir 400 mg of PVDF-HFP on a small stirrer. Stir at room temperature for more than 2 h until LiFSI and PVDF-HFP are completely dissolved to obtain a uniform transparent solution.

[0123] S32. Add 200 mg of LLZTO@Ag to the solution obtained in step S31 and stir at room temperature for more than 24 h to obtain a uniform black solution.

[0124] S33. Pour the solution obtained in step S32 into a glass culture dish, place it in a 60°C forced air oven and dry it for 24 hours to remove the solvent DMF to obtain a PVDF-HFP-LLZTO@Ag composite solid electrolyte membrane, punch it into a suitable size, and store it in an inert atmosphere for drying and use.

[0125] In step S4, according to the battery assembly process, the NCM811 positive electrode prepared in step S2, the PVDF-HFP-LLZTO@Ag-based solid electrolyte membrane prepared in step S3 and lithium metal are assembled into a full battery.

[0126] Example 8

[0127] This embodiment provides a composite positive electrode and an assembled full battery, which are assembled according to the following steps:

[0128] Step S1, prepare the composite cathode slurry: First, weigh 90 mg of PVDF (binder) and place it in a stirring bottle. Add 1 mL of NMP (N-methylpyrrolidone) and stir on a small stirrer for 1 hour until the PVDF is completely dissolved. Then, add 90 mg of SuperP (conductive carbon black) and 1 mL of NMP and stir at room temperature for 1 hour. Then, add 20 mg of LLZTO@Ag ionic electronic mixed conductor ceramic, 800 mg of NCM811 active material, and 1.5 mL of NMP and stir at room temperature for more than 6 hours.

[0129] Step S2, preparing a composite positive electrode: coating the positive electrode slurry obtained in step S1 on aluminum foil, drying at 80° C. for more than 6 h, cutting into a suitable size to obtain an NCM811 positive electrode, and placing in a vacuum oven for drying and storage.

[0130] Step S3, preparing a PVLA composite solid electrolyte according to the method of Example 2:

[0131] In step S4, according to the battery assembly process, the NCM811 positive electrode prepared in step S2, the PVLA solid electrolyte membrane prepared in step S3 and lithium metal are assembled into a full battery.

[0132] The present invention has the following technical advantages:

[0133] The modified ceramic of the present invention solves the problem of low dielectric constant of existing solid electrolytes; solves the problem of difficult lithium salt dissociation and low ion conductivity in existing solid electrolytes; and solves the problem of poor rate performance of existing solid electrolytes.

[0134] The ionic electronic hybrid ceramic LLZTO@Ag ceramic particles of the present invention have both ionic conductivity and electronic conductivity. This unique property is different from existing ceramics and can simultaneously transport electrons and ions. It can be combined with polymer electrolytes to improve the dielectric properties of the composite electrolyte body. Compared with existing polymer solid electrolytes, the composite solid electrolyte of the present invention has the advantages of high dielectric constant, high degree of lithium salt dissociation, high ionic conductivity and ion migration number. It also has excellent mechanical properties and can achieve high-rate operation. The production method of the composite solid electrolyte and gradient SEI is simple, which greatly reduces production costs. In addition, the performance of the solid electrolyte is greatly improved, with obvious technical and cost advantages.

[0135] The solid electrolyte of the present invention has a higher dielectric constant, ionic conductivity, and ion transference number, while having a similar cost to conventional solid electrolytes. It can simultaneously solve the problems of difficult dissociation of electrolyte lithium salts, low ionic conductivity, and poor resistance to lithium dendrite growth, thereby achieving stable high-rate operation of the battery. Conventional composite electrolytes cannot simultaneously address issues such as ionic conductivity and interfacial stability. It can solve safety issues such as fire and explosion caused by conventional batteries using electrolytes, and has high research value and application prospects.

[0136] The background section of the present invention may contain background information about the problem or environment of the present invention, but does not necessarily describe the prior art. Therefore, the inclusion of content in the background section is not an admission by the applicant that the prior art is present.

[0137] The above description further details the present invention in conjunction with specific / preferred embodiments, and the specific implementation of the present invention should not be construed as being limited to these descriptions. Persons skilled in the art will appreciate that, without departing from the spirit of the present invention, they may make various substitutions or modifications to the described embodiments, and these substitutions or modifications should be considered to fall within the scope of protection of the present invention. Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "preferred embodiments," "examples," "specific examples," or "some examples" indicates that the specific features, structures, materials, or characteristics described in conjunction with such embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Persons skilled in the art may combine and assemble the different embodiments or examples described in this specification, as well as features of different embodiments or examples, without conflicting opinions. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions, and modifications may be made herein without departing from the scope of protection of the patent application.

Claims

1. An ion-electron mixed conductor ceramic, characterized in that: Including Ag-modified LLZTO ceramics.

2. The ionic-electronic mixed conductor ceramic according to claim 1, characterized in that: The LLZTO is Li 6.5 LqCy 1.5 Ta 0.5 O 12 or Li7La3Zr2O 12 Or its doped derivative ceramics.

3. A method for preparing an ionic-electronic mixed conductor ceramic, characterized in that: The following steps are involved: The LLZTO ceramic is added into a solution containing a soluble silver salt and a reducing agent to obtain silver oxide; The silver oxide reacts under the action of the reducing agent to obtain Ag-modified LLZTO ceramics.

4. The preparation method according to claim 3, characterized in that: The soluble silver salt is one of AgNO3, AgClO3 and AgClO4.

5. The preparation method according to claim 3, characterized in that: The reducing agent is one of ethanol, sulfurous acid, sodium sulfite and hydrogen peroxide.

6. A composite solid electrolyte, characterized in that: The invention comprises the ionic electronic mixed conductor ceramic according to any one of claims 1 to 2, a lithium salt and a polymer.

7. The composite solid electrolyte according to claim 6, characterized in that The lithium salt is lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethylsulfonyl)imide, lithium hexafluorophosphate or lithium tetrafluoroborate; the polymer is poly(ethylene oxide) PEO, poly(vinylidene fluoride) PVDF or poly(vinylidene fluoride-hexafluoropropylene) PVDF-HFP.

8. A method for preparing a solid electrolyte according to any one of claims 6 to 7, characterized in that: The polymer, the lithium salt and the ion-electron mixed conductor ceramic are uniformly mixed in a certain proportion to prepare a solid electrolyte.

9. A battery electrode material, characterized in that: It comprises the ionic-electronic mixed conductor ceramic as claimed in claim 1 or 2.

10. A battery, characterized in that: It comprises the ionic-electronic mixed conductor ceramic as claimed in claim 1 or 2, or the solid electrolyte as claimed in claim 6 or 7.

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