Interface modification material with high failure threshold value, solid electrolyte and all-solid-state battery

Abstract

The invention discloses an interface modification material with a high failure threshold, a solid electrolyte and an all-solid-state battery, and relates to the technical field of electrochemistry. The interface modification material comprises a lithium salt, polymer particles, nanometer indium oxide particles and nanometer NASICON type solid electrolyte powder, the solid electrolyte is obtained by modifying the NASICON type solid electrolyte through the interface modification material, and the all-solid-state battery can be prepared through the solid electrolyte. According to the interface modification material, the cycle performance of the all-solid-state battery at room temperature can be improved, and meanwhile, the interface critical failure threshold can be increased.

Description

Technical Field

[0001] The present invention relates to the technical field of all-solid-state batteries, and specifically to an interfacial modification material, a solid electrolyte, and an all-solid-state battery with a high failure threshold. Background Art

[0002] In recent years, with the surge in the demand for high-energy-density energy storage, all-solid-state lithium-metal batteries have become a research hotspot due to their inherent safety and theoretical energy density advantages. As a core component, NASICON-type solid electrolytes have attracted much attention due to their high room-temperature ionic conductivity (i.e., room-temperature ionic conductivity > 10 -4 S / cm), wide electrochemical window (electrochemical window > 5 V vs. Li+ / Li), stable chemical properties, and low-cost characteristics. However, the interfacial compatibility problem between NASICON-type solid electrolytes and lithium-metal anodes severely restricts their practical applications. Among them, Ti 4+ and Ge 4+ are easily reduced by lithium metal, triggering interfacial side reactions and forming a high-impedance layer. In addition, uneven local current distribution during lithium deposition caused by poor solid-solid interface contact leads to the growth of lithium dendrites, which may pierce the electrolyte and cause a short circuit.

[0003] Introducing a modification layer is a very effective solution. Coatings such as alumina prepared by atomic deposition or magnetron sputtering have been proven to be feasible methods. However, the ion-insulating coating hinders ion diffusion, affects the performance of solid-state batteries, and the process is complex and expensive. Polymers have flexibility, adjustable lithium salt concentration, and good interfacial compatibility with lithium-metal anodes. Based on the above advantages, polymers are considered suitable as NASICON-type electrolyte modification layers. However, the low room-temperature ionic conductivity of the PEO (polyethylene oxide)-based modification layers used in a large number of studies greatly limits their applications. And due to insufficient lithium-ion flux and poor mechanical strength, the PEO-based intermediate layer still faces the problem of lithium dendrite growth.

[0004] Therefore, there is an urgent need for a composite interface design that combines interfacial chemical stability, lithium dendrite inhibition ability, and process compatibility to break through the room-temperature performance bottleneck of NASICON-type solid electrolyte batteries. Summary of the Invention

[0005] To solve at least one of the above problems, the present invention proposes an interfacial modification material, a solid electrolyte, and an all-solid-state battery with a high failure threshold.

[0006] The technical solution of the present invention is as follows: An interfacial modification material with a high failure threshold, comprising a lithium salt, polymer particles, nano-indium oxide particles, nano-NASICON type solid electrolyte powder, and a dispersant. Among them, the mass ratio of the lithium salt, polymer particles, nano-indium oxide particles, and nano-NASICON type solid electrolyte powder is 1:0.5 - 1:0.1 - 0.2:0.1 - 0.3.

[0007] In the present invention, each of the added components has its own function: The polymer particles are flexible and can effectively reduce the adverse effects caused by the volume change of the electrolyte during the operation of the battery. Therefore, for the polymer particles, common polymer particles in the art can be used; The added nano-indium oxide will undergo an in-situ reaction with lithium metal at the interface to form an ion and electron composite conductive layer composed of a lithium-indium alloy and lithium oxide. This composite conductive layer can promote the uniform deposition of lithium at the interface and effectively enhance the long-term stability performance of the interface; The lithium salt serves as an ion transport carrier to increase the ionic conductivity of the modification layer and transport lithium ions; The electrolyte powder can also increase the transport of lithium ions and enhance the mechanical properties of the modification layer.

[0008] At the same time, since in the present invention, the addition amount of the polymer particles is small while the addition amount of the lithium salt is large, a salt-in-polymer with the lithium salt as the main body will be formed. This salt-in-polymer can greatly improve the ionic conductivity of the electrolyte layer at room temperature and reduce the interfacial impedance.

[0009] One embodiment of the present invention is that the lithium salt is LiFSI (lithium bis(fluorosulfonyl)imide) or LiTFSI (lithium bis(trifluoromethanesulfonyl)imide), the polymer particles are PVDF-HFP (poly(vinylidene fluoride - hexafluoropropylene) copolymer) or P(VDF-TrFE-CTFE) (terpolymer of vinylidene fluoride - trifluoroethylene - chlorofluoroethylene), the nano-NASICON type solid electrolyte powder is nano-LATP powder or nano-LAGP powder, and the dispersant is one or several of dimethylformamide, dimethyl sulfoxide, or tetrahydrofuran; LiFSI and LiTFSI are common lithium salts in the art, PVDF-HFP and P(VDF-TrFE-CTFE) are common polymer solid electrolyte matrix materials, the chemical formula of LATP is Li 1+x Al x Ti 2-x (PO 4 ) 3 ₃, and the chemical formula of LAGP is Li 1+x Al x Ge 2-x (PO 4 ) 3, where x represents the doping amount of aluminum or germanium to titanium, and its range is usually 0.2 ≤ x ≤ 0.5. Preferably, LiFSI is Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 , and LAGP is Li 1.5 Ge 0.5 Ti 1.5 (PO 4 ) 3 .

[0010] Another object of the present invention is to propose a solid electrolyte, which uses the above-mentioned interface modification material with a high failure threshold to modify the NASICON-type solid electrolyte. The interface modification method includes the following steps: S1. Take the above-mentioned lithium metal all-solid-state battery interface modification material based on nano-indium oxide and disperse or dissolve it in a dispersant to prepare a precursor solution for the modification layer; the dispersant can dissolve lithium salts and polymer particles; S2. Coat the precursor solution for the modification layer in S1 on one or both sides of the NASICON-type solid electrolyte to form a solid electrolyte modification layer.

[0011] In S1, for each component in the interface modification material, the nano-indium oxide particles and the nano-NASICON-type solid electrolyte powder are in a dispersed state in the dispersant and are basically insoluble; while for the lithium salt and polymer particles, when a suitable dispersant is selected, they have good solubility. After the two are dissolved in the dispersant, a relatively uniform salt-in-polymer can be formed, and this salt-in-polymer can effectively improve the performance of the solid electrolyte.

[0012] For the NASICON-type solid electrolyte, it is a common solid electrolyte in the art. Specifically, the difference between the above-mentioned nano-NASICON-type solid electrolyte powder and the NASICON-type solid electrolyte here is only in size. This solid electrolyte can be purchased as a mature commercial product or can be prepared by self-made means. Its preparation method is as follows: Step 1: Take the raw materials of the NASICON-type solid electrolyte, such as lithium carbonate, aluminum oxide, titanium dioxide, and ammonium dihydrogen phosphate. The dosages of these raw materials can be determined with reference to their specific molecular structural formulas. After ball milling to refine the particle size, it is cold isostatically pressed at a pressure of 50 - 500 Mpa for 1 - 10 minutes to form.

[0013] Step 2: Sinter it in an air atmosphere to make it densified. The sintering temperature is 800°C - 1300°C, and the sintering time lasts for 4h - 24h. After completion, wait for it to cool, and then polish it to obtain.

[0014] Of course, the above preparation method is only one of the methods, and those skilled in the art can select the remaining methods for preparation according to the prior art and actual situations.

[0015] Meanwhile, for the above NASICON-type solid electrolyte, its size can be set according to actual situations: its diameter can be designed according to the size of the battery case, and its thickness can refer to the thickness of conventional solid electrolytes, such as 1 mm.

[0016] One embodiment of the present invention is that the dispersant is one of dimethylformamide, dimethyl sulfoxide or tetrahydrofuran; the thickness of the solid electrolyte modification layer is 5 - 100 μm. For the dispersant, its main function is to dissolve the lithium salt and polymer particles, and disperse the nano indium oxide particles and nano NASICON-type solid electrolyte powder. As long as the above conditions can be met, it can be applied to the present invention. For the thickness of the solid electrolyte modification layer, after a large number of experiments, it is found that the thickness can be set to 5 - 100 μm.

[0017] One embodiment of the present invention is that in S2, when the precursor solution of the modification layer is coated on one side of the NASICON-type solid electrolyte, a liquid electrolyte layer or a solid electrolyte layer is provided on the other side of the NASICON-type solid electrolyte.

[0018] Currently, there are the following two types of lithium solid-state batteries: lithium solid-state full batteries, which are composed of a positive electrode and a negative electrode. Among them, lithium metal is the negative electrode, the middle part is the electrolyte, and the other side is the positive electrode; lithium solid-state symmetric batteries, the difference between which and the full batteries is that both of their electrodes are lithium metal.

[0019] For the lithium solid-state full battery, a solid electrolyte modification layer of the present invention is provided on one side, and the solid electrolyte modification layer is in contact with lithium metal; for the other side, due to the poor contact between the NASICON-type solid electrolyte and the positive electrode material, generally, a certain modification layer or liquid electrolyte needs to be introduced to solve this problem.

[0020] For existing lithium solid-state all-solid-state batteries, the modification layer of the positive electrode either has the defect of inconvenient use (liquid electrolyte layer) or has the defect of low room-temperature conductivity (conventional solid electrolyte layer). In the present invention, a new solid electrolyte layer is proposed. The difference between this solid electrolyte layer and the interface modification material proposed in the present invention is that it does not contain nano-indium oxide: it is composed of a lithium salt, polymer particles, and nano-NASICON type solid electrolyte powder with a mass ratio of 1:0.5 to 1:0.1 to 0.3; the lithium salt is LiFSI or LiTFSI, the polymer particles are PVDF-HFP or P(VDF-TrFE-CTFE), and the nano-NASICON type solid electrolyte powder is nano-LATP powder or nano-LAGP powder; the nano-LATP powder is nano-Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 powder, and the nano-LAGP powder is nano-Li 1.5 Ge 0.5 Ti 1.5 (PO 4 ) 3 powder.

[0021] When in use, its usage method is the same as that of the interface modification material: adding a dispersant to dissolve or disperse it, and then coating it on the other side of the NASICON type solid electrolyte to obtain it. The dispersant used here is the same as the above dispersant, and one or several of dimethylformamide, dimethyl sulfoxide, or tetrahydrofuran can be selected.

[0022] Furthermore, the solid electrolyte layer is composed of a lithium salt, polymer particles, and nano-NASICON type solid electrolyte powder with a mass ratio of 1:0.5 to 1:0.1 to 0.3; the lithium salt is LiFSI or LiTFSI, the polymer particles are PVDF-HFP or P(VDF-TrFE-CTFE), and the nano-NASICON type solid electrolyte powder is nano-LATP powder or nano-LAGP powder; the nano-LATP powder is nano-Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 powder, and the nano-LAGP powder is nano-Li 1.5 Ge 0.5 Ti 1.5 (PO 4 ) 3 powder.

[0023] One embodiment of the present invention is that in S2, the method of coating the precursor solution of the modification layer includes drop coating, spin coating, spraying or coating, which are common coating methods in the art.

[0024] Another object of the present invention is to provide a all-solid-state battery, including a battery encapsulation case, wherein the above-mentioned solid electrolyte is provided in the battery encapsulation case, and one side or both sides of the solid electrolyte provided with the solid electrolyte modification layer are in close contact with lithium metal. According to the different numbers of solid electrolyte modification layers, the types of all-solid-state batteries are different: when the solid electrolyte modification layers are provided on both sides of the solid electrolyte, one layer of lithium metal is in close contact with each side, and the finally prepared battery is called a lithium solid-state symmetric battery in the art; when the solid electrolyte modification layer is only provided on one layer of the solid electrolyte, the other side of the solid electrolyte is not provided with lithium metal, but a battery positive electrode, and such a battery is called a lithium solid-state full battery in the art.

[0025] Furthermore, due to the poor contact between the NASICON-type solid electrolyte and the positive electrode material, when one side of the solid electrolyte is provided with an electrolyte modification layer, the other side is provided with a liquid electrolyte layer or a solid electrolyte layer, and one side of the liquid electrolyte layer or the solid electrolyte layer is in close contact with the positive electrode.

[0026] Beneficial effects: 1. The present invention introduces a salt-in-polymer added with nano indium oxide between the lithium metal and the NASICON-type solid electrolyte. Nano indium oxide and lithium metal react in situ at the interface to form an ionic and electronic composite conductive layer composed of lithium indium alloy and lithium oxide. This composite conductor promotes the uniform deposition of lithium at the interface, effectively enhancing the long-term stability of the interface. The use of the salt-in-polymer greatly improves the ionic conductivity at room temperature, reduces the interface impedance, and significantly improves the cycle performance of the all-solid-state battery at room temperature.

[0027] 2. The present invention introduces a salt-in-polymer between the positive electrode sheet and the NASICON-type solid electrolyte to avoid using a flammable liquid electrolyte system. The flexible polymer layer effectively reduces the adverse effects caused by the volume change that occurs during the operation of the battery between the electrode and the electrolyte.

[0028] 3. The present invention uses a lithium symmetric battery to quickly and accurately evaluate the critical failure threshold of the interface modification layer. The critical current density test of the lithium symmetric battery can quickly evaluate the interface performance to achieve efficient search for the optimal material ratio. The interface modification method based on nano indium oxide in the present invention significantly improves the critical failure threshold of the interface. Description of the Drawings

[0029] Figure 1 is a cross-sectional microscopic scan of the solid electrolyte 1; Figure 2 For the all-solid-state battery 1 and the all-solid-state battery 4 at 0.5 mA cm-2 Graph of the lithium symmetric battery performance test results under certain conditions; Figure 3 Graph of the lithium symmetric battery performance test results for all-solid-state batteries 1 to 4 at 1 mA cm -2 conditions; Figure 4 Graph of the full-cell performance test results for all-solid-state battery 7 at 1C; Figure 5 Graph of the full-cell performance test results for all-solid-state battery 5 at 1C; Figure 6 Graph of the full-cell performance test results for all-solid-state battery 5 at 5C; Figure 7 Graph of the full-cell performance test results for all-solid-state battery 6 at 0.3C; Figure 8 Graph of the full-cell performance test results for all-solid-state battery 6 at 1C; Figure 9 Graph of the evaluation test results of the critical failure threshold at the interface between all-solid-state battery 1 and all-solid-state battery 4. Detailed implementation method

[0030] Next, the specific implementation method of the present invention will be clearly and completely described in combination with examples and drawings. Obviously, the described examples are only a part of the embodiments of the present invention, rather than all embodiments.

[0031] In the following examples, the preparation method of the NASICON-type solid electrolyte sheet is as follows: Step 1: Weigh 19.8 g of Li 2 CO 3 19.8g, 6.2g of Al2O 3 6.2g, 32.5g of TiO 2 32.5g, NH 4 H 2 PO 4 41.5g, mix and ball mill for 8 hours, pre-burn at 350°C for 4 hours to remove ammonium salts, and then calcine at 980°C for 12 hours. After crushing and ball milling, LATP mother powder is obtained.

[0032] Step 2: Take 0.3 g of the mother powder and place it in a 12 mm circular mold, perform cold isostatic pressing for 1 min at a pressure of 280 MPa to obtain a white circular sheet.

[0033] Step 3: Place the white original sheet in a muffle furnace and sinter at 900°C for 5 h in an air atmosphere to obtain an LATP solid electrolyte sheet with a diameter of about 10.5 mm.

[0034] Step 4: Take the sintered LATP solid electrolyte sheet and polish it successively on 800-mesh and 2000-mesh SiC sandpapers. Then, use an electric polisher with 0.5-μm diamond abrasive polishant to perform wet polishing on the electrolyte sheet to make both sides of the electrolyte sheet flat. The thickness of the polished electrolyte sheet is 1 mm and the diameter is 10.5 mm.

[0035] In the following examples, unless otherwise specified, the reagents used are all conventional commercial products.

[0036] In the following examples, unless otherwise specified, the methods used are all conventional operations in the art.

[0037] Example 1: An interfacial modification material, comprising: 0.4 g of LiFSI, 0.3 g of PVDF-HFP, 0.08 g of nano-NASICON type solid electrolyte powder, and 0.06 g of nano-indium oxide powder.

[0038] Example 2: An interfacial modification material, comprising: 0.4 g of LiFSI, 0.3 g of PVDF-HFP, 0.08 g of nano-NASICON type solid electrolyte powder, and 0.04 g of nano-indium oxide powder.

[0039] Example 3: An interfacial modification material, comprising: 0.4 g of LiFSI, 0.3 g of PVDF-HFP, 0.08 g of nano-NASICON type solid electrolyte powder, and 0.08 g of nano-indium oxide powder.

[0040] Example 4: An interfacial modification material, comprising: 0.4 g of LiFSI, 0.3 g of PVDF-HFP, and 0.08 g of nano-NASICON type solid electrolyte powder.

[0041] Example 5: A method for modifying a solid electrolyte, comprising the following steps: Take the interfacial modification materials of Examples 1 to 3, and respectively add 5 g of dimethylformamide. After the NASICON type solid electrolyte powder and nano-indium oxide are uniformly dispersed and the LiFSI and PVDF-HFP particles are dissolved, the modified layer precursor solutions 1 to 3 are obtained.

[0042] Take NASICON type solid electrolyte sheets, and adopt a stepwise drop-coating process. Under an argon atmosphere, respectively drop 20 μL of the modified layer precursor solutions 1 to 3 on one side of the NASICON type solid electrolyte sheets. After drying at 50 °C, take the same modified layer precursor solution and drop it on the other side of the NASICON type solid electrolyte sheets, and continue drying to obtain the solid electrolytes 1 to 3.

[0043] Comparative Example 1: Take the interface modification material of Example 4, add 5 g of dimethylformamide, and wait until the NASICON-type solid electrolyte powder is uniformly dispersed and the LiFSI and PVDF-HFP particles are dissolved to obtain the precursor solution 4 of the modification layer.

[0044] Take a NASICON-type solid electrolyte sheet, and adopt a stepwise drop-coating process. Under an argon atmosphere, drop 20 μL of the precursor solution 4 of the modification layer on one side of the NASICON-type solid electrolyte sheet. After drying at 50 °C, take the same precursor solution of the modification layer and drop it on the other side of the NASICON-type solid electrolyte sheet, and continue drying to obtain the solid electrolyte 4.

[0045] Example 6: A method for modifying a solid electrolyte, comprising the following steps: Take the interface modification material of Example 1, add 5 g of dimethylformamide, and wait until the NASICON-type solid electrolyte powder and indium oxide nanoparticles are uniformly dispersed and the LiFSI and PVDF-HFP particles are dissolved to obtain the precursor solution 1 of the modification layer; take the interface modification material of Example 4, add 5 g of dimethylformamide, and wait until the NASICON-type solid electrolyte powder is uniformly dispersed and the LiFSI and PVDF-HFP particles are dissolved to obtain the precursor solution 4 of the modification layer.

[0046] Take a NASICON-type solid electrolyte sheet, and adopt a stepwise drop-coating process. Under an argon atmosphere, drop 20 μL of the precursor solution 1 of the modification layer on one side of the NASICON-type solid electrolyte sheet. After drying at 50 °C, drop 20 μL of the precursor solution 4 of the modification layer on the other side of the NASICON-type solid electrolyte sheet, and continue drying to obtain the solid electrolyte 5.

[0047] Example 7: A all-solid-state battery, comprising a 2032-type button battery case. Take lithium metal sheets with a diameter of 8 mm and a thickness of 0.45 mm respectively and fix them on both sides of the solid electrolytes 1 to 4 to form a sandwich structure of lithium metal / solid electrolyte / lithium metal. Then, press and encapsulate this sandwich structure into the aforementioned battery case to obtain the all-solid-state batteries 1 to 4.

[0048] Example 8: A all-solid-state battery, comprising a 2023-type button battery case. Take the solid electrolyte 5, fix a lithium metal sheet on the side coated with the precursor solution 1 of the modification layer, and fix an electrode sheet on the side coated with the precursor solution 4 of the modification layer. Then, press and encapsulate it into the aforementioned battery case to obtain the all-solid-state battery 5; wherein, the lithium metal sheet has a diameter of 8 mm and a thickness of 0.45 mm, and the electrode sheet is a lithium iron phosphate (LFP) electrode sheet with a areal capacity of 1.25 mg cm -2 Lithium iron phosphate (LFP) electrode sheet.

[0049] Example 9: The difference between this example and Example 8 is that the electrode sheet is an NMC811 electrode sheet (9.2 mg cm-2 , with the proportion of the active substance as high as 94.5%), and the rest are the same, and finally the all-solid-state battery 6 is obtained.

[0050] Comparative Example 2: The difference between this comparative example and Example 8 is that for the solid electrolyte used, both sides are modified with the modifier precursor solution 4, and the rest are the same, and the all-solid-state battery 7 is obtained.

[0051] To further illustrate the advantages of the products of the embodiments of the present invention, specific performance tests are carried out below.

[0052] 1. Microscopic scanning: The solid electrolyte 1 is scanned using a scanning electron microscope, and the results are as Figure 1 shown. It can be seen that the modification layer is successfully modified, and its thickness is about 8.5 μm.

[0053] 2. Half-cell performance test: Use a Neware battery test system to perform charge and discharge cycles on a lithium symmetric battery at 0.5 mA cm -2 and 1 mA cm -2 . The charging time is 0.5 h, the discharging time is 0.5 h, and the charge and discharge alternate without rest time.

[0054] Figure 2 are the test results of the all-solid-state battery 1 and the all-solid-state battery 4 under the condition of 0.5 mA cm -2 . It can be seen from the figure that the all-solid-state battery 1, under the condition of 0.5 mA cm -2 , does not fail after cycling for more than 3000 hours; while the all-solid-state battery 4 of Comparative Example 1 fails after only cycling for more than two hundred hours.

[0055] Figure 3 are the test results of the all-solid-state batteries 1-4 under the condition of 1 mA cm -2 . From Figure 3 it can be seen that when the modification material of the embodiments of the present invention is applied to a symmetric battery, the addition amount of indium oxide needs to be within a certain range, and too much or too little is not beneficial.

[0056] The above test results show that the modified materials and solid electrolytes of the embodiments of the present invention greatly enhance the ability of lithium stripping and deposition.

[0057] 2. Full-cell performance test: Use a Neware battery test system to perform charge and discharge cycle tests on the above all-solid-state battery at 1C and 5C, and the test voltage is 2.5-4.0V, and the results are as Figures 4 to 8 shown. In the figure, the yellow part represents the discharge capacity test result, and the blue part represents the Coulomb efficiency test result.

[0058] Figure 4Test results of all-solid-state battery 7 under 1C condition. As can be seen from the figure, when the number of cycles is less than 300, the battery has failed and lost all its capacity.

[0059] Figure 5 Test results of all-solid-state battery 5 under 1C condition. As can be seen from the figure, after 1000 cycles, it still has a high capacity of 140.76 mAh cm -2 , and the capacity hardly decays; Figure 6 Test results of all-solid-state battery 5 under 5C condition. As can be seen from the figure, even under the relatively large 5C current condition, it still shows excellent cycling performance. During the whole test process, its highest capacity is 119.43 mAh cm -2 , and after 5000 cycles, its battery discharge capacity is still 109.00 mAh cm -2 , which is 91.26% of the highest discharge capacity. At the same time, under the conditions of 1C and 5C, the average Coulombic efficiency of this battery is close to 100%, indicating that the performance of the battery in the embodiments of the present invention is relatively superior.

[0060] Figure 7 and Figure 8 are respectively the test results of all-solid-state battery 6 under 0.3C and 1C conditions, and the test voltage is 3.0 - 4.3V. As can be seen from the figure, in the face of the high-areal-capacity high-voltage oxide cathode, the modified battery also shows excellent cycling performance. At 0.3C current, after 260 cycles, the battery capacity retention rate is 81.82%. And under 1C condition, after 126 cycles, the battery capacity retention rate is 88.57%.

[0061] This shows that the modified materials and solid electrolytes in the embodiments of the present invention can not only be adapted to the low-areal-capacity low-voltage cathodes, but also show high performance in the face of the high-areal-capacity high-voltage cathodes.

[0062] 3. Evaluation of the critical failure threshold at the interface: Using a Neware battery test system, the critical current density (CCD) tests were carried out on the above-mentioned all-solid-state battery 4 and all-solid-state battery 1. The current density was gradually increased from low to high and applied to the all-solid-state battery. At each current density, it was charged for 0.5 hours and then discharged for 0.5 hours. The current density started from 0.2 mA cm -2 , and increased by 0.2 mA cm -2 each time after charge and discharge until 5 mA cm -2 . The voltage changes during the whole process were recorded. The results are as Figure 9 shown.

[0063] The failure threshold of the modified layer of all-solid-state battery 4 is 2.2 mA cm -2, while the failure threshold of the modified layer of the all-solid-state battery 1 is 4.2 mA cm -2 . This indicates that the introduction of indium oxide nanoparticles forms a more stable interfacial layer with lithium metal. A higher interfacial critical failure threshold is conducive to achieving fast charging and high-rate discharging of all-solid-state batteries.

[0064] The above are only the preferred embodiments of the present invention and do not impose any form of limitation on the present invention. Although the present invention is disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments by using the above-disclosed technical content within the scope of the technical solution of the present invention. However, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. An interface modification material with a high failure threshold, characterized in that: It includes lithium salt, polymer particles, nano indium oxide particles and nano NASICON solid electrolyte powder in a mass ratio of 1:0.5~1:0.1~0.2:0.1~0.

3.

2. The interface modification material according to claim 1, characterized in that: The lithium salt is LiFSI or LiTFSI, the polymer particles are PVDF-HFP or P(VDF-TrFE-CTFE), the nano NASICON solid electrolyte powder is nano LATP powder or nano LAGP powder; the nano LATP powder is nano Li 1.3 Al 0.3 Ti 1.7 (PO4)3 powder, the nano LAGP powder is nano Li 1.5 Ge 0.5 Ti 1.5 (PO4)3 powder.

3. A solid electrolyte, characterized in that The interface modification material with a high failure threshold as claimed in claim 1 or 2 is used to modify the interface of a NASICON solid electrolyte, and the interface modification method comprises the following steps: S1. Disperse or dissolve the interface modification material with a high failure threshold according to claim 1 in a dispersant to prepare a modification layer precursor solution; the dispersant can dissolve lithium salts and polymer particles; S2. Apply the modification layer precursor solution of S1 to one side or both sides of the NASICON solid electrolyte to form a solid electrolyte modification layer.

4. The solid electrolyte according to claim 3, characterized in that The dispersant is one or more of dimethylformamide, dimethyl sulfoxide or tetrahydrofuran; and the thickness of the solid electrolyte modification layer is 5-100 μm.

5. The solid electrolyte according to claim 3, characterized in that In S2, when the modification layer precursor solution is coated on one side of the NASICON type solid electrolyte, a liquid electrolyte layer or a solid electrolyte layer is provided on the other side of the NASICON type solid electrolyte.

6. The solid electrolyte according to claim 5, characterized in that The solid electrolyte layer is composed of lithium salt, polymer particles and nano NASICON solid electrolyte powder in a mass ratio of 1:0.5-1:0.1-0.

3.

7. The solid electrolyte according to claim 6, characterized in that The lithium salt is LiFSI or LiTFSI, the polymer particles are PVDF-HFP or P(VDF-TrFE-CTFE), the nano NASICON solid electrolyte powder is nano LATP powder or nano LAGP powder; the nano LATP powder is nano Li 1.3 Al 0.3 Ti 1.7 (PO4)3 powder, the nano LAGP powder is nano Li 1.5 Ge 0.5 Ti 1.5 (PO4)3 powder.

8. The solid electrolyte according to claim 3, characterized in that In S2, the method of coating the precursor solution of the modification layer includes drop coating, spin coating, spray coating or coating.

9. An all-solid-state battery, characterized in that: The invention comprises a battery packaging shell, wherein the solid electrolyte according to any one of claims 3 to 8 is arranged in the battery packaging shell, and one side or both sides of the solid electrolyte modification layer provided with the solid electrolyte are in close contact with lithium metal.

10. The all-solid-state battery according to claim 9, characterized in that: When an electrolyte modification layer is provided on one side of the solid electrolyte, a liquid electrolyte layer or a solid electrolyte layer is provided on the other side thereof, and one side of the liquid electrolyte layer or the solid electrolyte layer is in close contact with the positive electrode.

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