Solid-state electrolyte and preparation method thereof, and solid-state battery

Abstract

The application discloses a kind of solid electrolyte and preparation method thereof, solid-state battery, solid electrolyte is made of polymer, and lithium salt and additive dispersed in polymer, additive includes inorganic nano-particle, plasticizer and ionic liquid, polymer is one of polyvinyl ether of formula P1 to formula P7, the number average molecular weight of polymer is 1×10 4 -10×10 4 ;Wherein, m is positive integer, Cy is cyclohexyl, i Bu is isobutyl, n Bu is n-butyl, Bn is benzyl.The polyvinyl ether used in the application is a stereoregular polymer, the main chain and side chain do not contain active hydrogen chemical groups (such as hydroxyl), which can significantly reduce the tendency of electrolyte oxidation and decomposition under high pressure, and significantly improve the electrochemical window.The electrochemical window of the solid-state battery of the application is increased to 4.8V or more.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more specifically, to a solid electrolyte and its preparation method, and a solid battery. Background Technology

[0002] With the rapid development of electric vehicles, higher demands are being placed on the safety and energy density of power batteries. Currently, lithium-ion batteries generally use flammable liquid electrolytes, posing high safety risks. Replacing the original liquid electrolyte with a solid electrolyte is an effective way to solve the safety performance issues of lithium-ion batteries. Solid-state lithium batteries are considered by the industry to be the next generation of high-energy-density, high-safety batteries most likely to be widely adopted.

[0003] Research on all-solid-state lithium batteries using PEO as the solid electrolyte is the most mature. However, PEO electrolyte has a low voltage tolerance window (less than 4.0V), limiting its application to lithium iron phosphate systems. To further improve the energy density of solid-state batteries, using higher-capacity cathode materials has become the preferred approach. Currently, high-nickel ternary materials are the most widely used among high-capacity cathode materials.

[0004] Compared with lithium iron phosphate all-solid-state batteries, there are several difficulties in preparing high-nickel ternary all-solid-state batteries: (1) The charging voltage of high-nickel ternary cathode materials is relatively high, generally 4.2V and above, while the voltage resistance of traditional PEO-based electrolytes is less than 4.0V. Therefore, it is necessary to provide a solid electrolyte with a voltage resistance higher than 4.2V; (2) High-nickel ternary cathode materials in the charged state (fully charged state) have strong chemical oxidation properties, and the solid electrolyte in contact with them must have very good chemical oxidation resistance; (3) Conventional high-voltage resistant solid electrolytes are relatively unstable in the low potential range and are prone to react with the lithium metal anode.

[0005] Therefore, there is an urgent need to provide a high-voltage resistant solid electrolyte and its preparation method, as well as a solid-state battery. Summary of the Invention

[0006] In view of this, the present invention provides a high-voltage resistant solid electrolyte and its preparation method, as well as a solid battery. The solid electrolyte can withstand high voltages above 4.8V and is suitable for ternary systems with high requirements for solid electrolytes.

[0007] On one hand, the present invention provides a solid electrolyte made of a polymer, a lithium salt dispersed in the polymer, and additives, wherein the additives include inorganic nanoparticles, plasticizers, and ionic liquids, and the polymer is a polyvinyl ether of one of formulas P1 to P7, and the number average molecular weight of the polymer is 1 × 10⁻⁶. 4 -10×10 4 ;

[0008]

[0009] Where m is a positive integer, and Cy is a cyclohexyl basis. i Bu is isobutyl. n Bu is n-butyl, and Bn is benzyl.

[0010] The polymer used in this invention is polyethylene ether, a stereoisotactic polymer whose structural units contain ether bonds, enabling it to complex and rapidly transfer lithium ions. This solid electrolyte can withstand high voltages above 4.8V and is suitable for ternary systems with high electrolyte requirements.

[0011] For methods of polymer synthesis that are existing technologies, please refer to, for example, WO_2022151797_A1; JACS, 143, 16388-16393; Science, 363, 1439-1443; Polym. Chem., 2024, 15, 1062-1969.

[0012] The number-average molecular weight of the polymer in this invention is 1×10⁻⁶. 4 -10×10 4 Optional, it can be 1×10 4 2×10 4 3×10 4 4×10 4 5×10 4 6×10 4 7×10 4 8×10 4 9×10 4 10×10 4 If the number-average molecular weight is too high, the solubility is poor; if the number-average molecular weight is too low, it is in a liquid state and has poor molding properties. In this invention, the polymer has a number-average molecular weight of 1 × 10⁻⁶. 4 -10×10 4 It has good solubility and film-forming properties.

[0013] In this invention, the addition of inorganic nanoparticles is beneficial to improving the strength of solid electrolytes, and the addition of plasticizers or ionic liquids is beneficial to improving the room temperature ionic conductivity of solid electrolytes.

[0014] Optionally, the mass ratio of polymer, lithium salt, and additives is 60%-75% : 10%-25% : 0%-15%.

[0015] Optionally, the mass ratio of polymer, lithium salt, and additive can be 75%:25%:0%, 60%:25%:15%, 70%:20%:10%, 75%:15%:10%, or any value between 60%-75%:10%-25%:0%-15%, without any specific limitation here.

[0016] Optionally, the inorganic nanoparticles are titanium dioxide, Li7La3Zr2O 12 、Li7La3Zr 1.5 Ta 0.5 O 12 One of them.

[0017] In this invention, Li7La3Zr2O 12 、Li7La3Zr 1.5 Ta 0.5 O 12 It has high ionic conductivity. When combined with polymers, it can not only reduce the cleanliness of the polymer matrix and increase the ionic conductivity, but also provide an additional ion transport pathway, further improving the electrochemical performance of the composite electrolyte.

[0018] Optional, plasticizers include succinic anhydride.

[0019] Succinate molecules possess a highly polar cyano group, which can interact with lithium salts, effectively dissociating the lithium salts and promoting lithium-ion transport. Furthermore, succinate can improve interfacial stability; succinate molecules can interact with the electrode surface to form a stable interfacial layer and reduce interfacial impedance.

[0020] Optionally, ionic liquids include piperidine salts.

[0021] Piperidine salts possess excellent thermal stability, high ionic conductivity, negligible vapor pressure, and non-flammability, making them suitable for enhancing the ionic conductivity of solid electrolytes.

[0022] Optionally, the lithium salt is at least one of lithium hexafluorophosphate, lithium perchlorate, lithium difluorooxalate borate, lithium bis(trifluoromethanesulfonyl)imide, and lithium bis(fluorosulfonyl)imide.

[0023] On the other hand, the present invention also provides a method for preparing a solid electrolyte, comprising:

[0024] S1, obtain the polymer, lithium salt and additives by mass fraction, and dissolve them in a volatile solvent to obtain a mixed solution;

[0025] S2, Apply the mixed solution evenly to the surface of the polytetrafluoroethylene sheet;

[0026] S3 is vacuum dried at 25℃-60℃ for 4-8 hours to remove volatile solvents, yielding a solid electrolyte.

[0027] Optionally, the volatile solvent can be tetrahydrofuran (THF).

[0028] Optionally, the vacuum drying temperature can be 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, or 60℃, or any value between 25℃ and 60℃. The vacuum drying time can be 4 hours, 4.5 hours, 5 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, 7.5 hours, or 8 hours, or any value between 4 hours and 8 hours.

[0029] Thirdly, the present invention also provides a solid-state battery, which includes a positive electrode, a negative electrode and a solid electrolyte located between the positive electrode and the negative electrode, wherein the solid electrolyte is the aforementioned solid electrolyte, and the electrochemical window of the solid-state battery is greater than or equal to 4.8V.

[0030] Optionally, the positive electrode includes a positive current collector and a positive electrode material coated on the surface of the positive current collector; the positive electrode material is composed of a ternary active material and an inorganic compound coated on the surface of the ternary active material.

[0031] Optionally, the ternary active material is LiNi. 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.7 Co 0.1 Mn 0.2 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.8 Co 0.15 Al 0.05 O2 or LiNi 0.9 Co 0.05 Al 0.05 O2.

[0032] Compared with the prior art, the solid electrolyte, its preparation method, and solid battery provided by the present invention achieve at least the following beneficial effects:

[0033] In existing technologies, PEO is used to make solid electrolytes, which contain active hydrogen groups. These active hydrogen groups pose a risk of oxidative decomposition. For example, active hydrogen groups such as hydroxyl (-OH) are easily oxidized to carbonyl (C=O) or carboxyl (-COOH) groups under high voltage (>4.0V), which further react with lithium ions to generate byproducts such as Li2CO3, leading to electrolyte decomposition and increased interfacial impedance. At the same time, active hydrogen groups can also cause a decrease in interfacial stability. The oxidation products of active hydrogen groups can damage the interface between the electrolyte and the electrode, triggering side reactions, thereby limiting the cycle life of the battery under high voltage.

[0034] This invention uses polyvinyl ether as a stereoisotactic polymer. Neither the main chain nor the side chains of polyvinyl ether contain chemical groups with active hydrogen (such as hydroxyl groups), which can significantly reduce the tendency of the electrolyte to oxidize and decompose under high voltage, and significantly improve the electrochemical window. Furthermore, by replacing the hydroxyl groups in the main chain and side chains with inert groups, polyvinyl ether can reduce interfacial side reactions, lower battery internal resistance, and extend cycle life.

[0035] The electrochemical window of the solid-state battery in this invention has been increased to above 4.8V.

[0036] Of course, any product implementing this invention does not necessarily need to achieve all of the technical effects described above at the same time.

[0037] Other features and advantages of the invention will become clear from the following detailed description of exemplary embodiments of the invention with reference to the accompanying drawings. Attached Figure Description

[0038] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the invention and, together with their description, serve to explain the principles of the invention.

[0039] Figure 1 This is a flowchart of a method for preparing a solid electrolyte provided by the present invention. Detailed Implementation

[0040] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention.

[0041] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0042] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0043] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0044] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0045] Examples 1 to 12 below are examples of the preparation method of solid electrolyte provided by the present invention and the corresponding solid electrolyte obtained therefrom. Comparative Example 1 is a preparation method of PEO-based solid electrolyte in the prior art and the corresponding solid electrolyte obtained therefrom.

[0046] Example 1

[0047] The method for preparing the solid electrolyte in this embodiment includes the following steps:

[0048] polymer (P1, M) n =9.5×10 4 A solid electrolyte is obtained by dissolving lithium hexafluorophosphate (LiPF6) in tetrahydrofuran (P1 / mol) at a mass percentage of 75% and 25%, respectively. The solution is then uniformly coated onto a polytetrafluoroethylene (PTFE) plate and dried under vacuum at 45°C for 6 hours to remove the tetrahydrofuran.

[0049] Example 2

[0050] polymer (P2, M) n =8.8×10 4 P2 (g / mol) and lithium perchlorate (LiClO4) are dissolved in tetrahydrofuran, wherein the mass percentages of P2 and LiClO4 are 75% and 25%, respectively. The solution is then uniformly coated onto a polytetrafluoroethylene plate, and the tetrahydrofuran is removed by vacuum drying at 45°C for 6 hours to obtain a solid electrolyte.

[0051] Example 3

[0052] polymer (P3, M) n =9.2×10 4 The electrolyte is prepared by dissolving lithium difluorooxalate borate (P3, g / mol) in tetrahydrofuran, wherein the mass percentages of P3 and lithium difluorooxalate borate are 75% and 25%, respectively. The solution is then uniformly coated onto a polytetrafluoroethylene (PTFE) plate and dried under vacuum at 45°C for 6 hours to remove the tetrahydrofuran, yielding a solid electrolyte.

[0053] Example 4

[0054] polymer (P4, M) n =7.3×104 Lithium bis(trifluoromethanesulfonyl)imide (TFSILi) was dissolved in tetrahydrofuran, with P4 and TFSILi having a mass percentage of 75% and 25%, respectively. The solution was then uniformly coated onto a polytetrafluoroethylene plate and dried under vacuum at 45°C for 6 hours to remove the tetrahydrofuran, yielding a solid electrolyte.

[0055] Example 5

[0056] polymer (P5, M) n =7.3×10 4 Lithium bis(trifluoromethanesulfonyl)imide (LiTFSi) was dissolved in tetrahydrofuran, with P5 and TFSILi having a mass percentage of 75% and 25%, respectively. The solution was then uniformly coated onto a polytetrafluoroethylene plate, and the tetrahydrofuran was removed by vacuum drying at 45°C for 6 hours to obtain the solid electrolyte.

[0057] Example 6

[0058] polymer (P6, M) n =5.6×10 4 Lithium bis(fluorosulfonyl)imide (LiFSi) was dissolved in tetrahydrofuran, with P6 and LiFSi having a mass percentage of 75% and 25%, respectively. The solution was then uniformly coated onto a polytetrafluoroethylene plate, and the tetrahydrofuran was removed by vacuum drying at 45°C for 6 hours to obtain a solid electrolyte.

[0059] Example 7

[0060] polymer (P7, M) n =7.5×10 4 Lithium bis(trifluoromethanesulfonyl)imide (LiTFSi) was dissolved in tetrahydrofuran, with P7 and LiFSi having mass percentages of 75% and 25%, respectively. The solution was then uniformly coated onto a polytetrafluoroethylene plate, and the tetrahydrofuran was removed by vacuum drying at 45°C for 6 hours to obtain the solid electrolyte.

[0061] Example 8

[0062] polymer (P7, M) n =7.8×10 4 P7, LiFSi, titanium dioxide, and succinate were dispersed in tetrahydrofuran, with mass percentages of 60%, 25%, 7.5%, and 7.5% for P7, LiFSi, titanium dioxide, and succinate, respectively. The solution was then uniformly coated onto a polytetrafluoroethylene (PTFE) plate and vacuum dried at 45°C for 6 hours to remove the tetrahydrofuran, yielding a solid electrolyte.

[0063] Example 9

[0064] polymer (P7, M) n =7.8×10 4 P7, lithium bis(trifluoromethanesulfonyl)imide (LiTFSi), titanium dioxide, and succinate were dispersed in tetrahydrofuran, wherein the mass percentages of P7, LiFSi, titanium dioxide, and succinate were 65%, 20%, 7.5%, and 7.5%, respectively. The solution was then uniformly coated onto a polytetrafluoroethylene plate and vacuum dried at 45°C for 6 hours to remove the tetrahydrofuran, yielding a solid electrolyte.

[0065] Example 10

[0066] polymer (P7, M) n =7.8×10 4 g / mol), lithium bis(trifluoromethanesulfonylimide) (LiTFSi), Li7La3Zr2O 12 Succinate is dispersed in tetrahydrofuran, including P7, LiFSi, and Li7La3Zr2O. 12 The mass percentages of succinate and diisocyanate are 60%, 25%, 7.5%, and 7.5%. The solution is then uniformly coated onto a polytetrafluoroethylene plate, and the tetrahydrofuran is removed by vacuum drying at 45°C for 6 hours to obtain the solid electrolyte.

[0067] Example 11

[0068] polymer (P7, M) n =7.8×10 4 g / mol), lithium bis(trifluoromethanesulfonylimide) (LiTFSi), Li7La3Zr 1.5 Ta 0.5 O 12 Succinate is dispersed in tetrahydrofuran, including P7, LiFSi, and Li7La3Zr2O. 12 The mass percentages of succinate and diisocyanate are 60%, 25%, 7.5%, and 7.5%. The solution is then uniformly coated onto a polytetrafluoroethylene plate, and the tetrahydrofuran is removed by vacuum drying at 45°C for 6 hours to obtain the solid electrolyte.

[0069] Example 12

[0070] polymer (P7, M) n =7.8×10 4 g / mol), lithium bis(trifluoromethanesulfonylimide) (LiTFSi), Li7La3Zr 1.5 Ta 0.5 O 12Succinate, 1-butyl-1-methylpiperidine bis(trifluoromethanesulfonyl)imide salt were dispersed in tetrahydrofuran, wherein the mass percentages of P7, LiFSi, titanium dioxide, succinate, and 1-butyl-1-methylpiperidine bis(trifluoromethanesulfonyl)imide salt were 60%, 25%, 7.5%, 3.75%, and 3.75%, respectively. The solution was then uniformly coated onto a polytetrafluoroethylene plate, and the tetrahydrofuran was removed by vacuum drying at 45°C for 6 hours to obtain the solid electrolyte.

[0071] Comparative Example 1

[0072] PEO(M) n =60×10 4 Lithium bis(trifluoromethanesulfonyl)imide (LiTFSi), titanium dioxide, succinate, and 1-butyl-1-methylpiperidine bis(trifluoromethanesulfonyl)imide salt were dispersed in tetrahydrofuran, wherein the mass percentages of PEO, LiFSi, titanium dioxide, succinate, and 1-butyl-1-methylpiperidine bis(trifluoromethanesulfonyl)imide salt were 60%, 25%, 7.5%, 3.75%, and 3.75%, respectively. The solution was then uniformly coated onto a polytetrafluoroethylene plate, and the tetrahydrofuran was removed by vacuum drying at 45°C for 6 hours to obtain the solid electrolyte.

[0073] Examples 13 to 22 below are specific embodiments of ternary solid-state batteries. In Comparative Example 2, the solid electrolyte in the solid-state battery is the solid electrolyte prepared in Comparative Example 1.

[0074] Example 13

[0075] In this embodiment of the ternary solid-state battery, the positive electrode is an 811 positive electrode sheet, the negative electrode is a lithium metal negative electrode, and the solid electrolyte located between the positive electrode and the negative electrode is the solid electrolyte prepared in Example 1. The above-mentioned positive electrode, solid electrolyte and negative electrode are assembled into a solid-state battery, and the battery cells are assembled in a stacked manner.

[0076] Example 14

[0077] In this embodiment of the ternary solid-state battery, the positive electrode is an 811 positive electrode sheet, the negative electrode is a lithium metal negative electrode, and the solid electrolyte located between the positive electrode and the negative electrode is the solid electrolyte prepared in Example 2. The above-mentioned positive electrode, solid electrolyte and negative electrode are assembled into a solid-state battery, and the battery cells are assembled in a stacked manner.

[0078] Example 15

[0079] In this embodiment of the ternary solid-state battery, the positive electrode is an 811 positive electrode sheet, the negative electrode is a lithium metal negative electrode, and the solid electrolyte located between the positive electrode and the negative electrode is the solid electrolyte prepared in Example 4. The above-mentioned positive electrode, solid electrolyte and negative electrode are assembled into a solid-state battery, and the battery cells are assembled in a stacked manner.

[0080] Example 16

[0081] In this embodiment of the ternary solid-state battery, the positive electrode is an 811 positive electrode sheet, the negative electrode is a lithium metal negative electrode, and the solid electrolyte located between the positive electrode and the negative electrode is the solid electrolyte prepared in Example 5. The above-mentioned positive electrode, solid electrolyte and negative electrode are assembled into a solid-state battery, and the battery cells are assembled in a stacked manner.

[0082] Example 17

[0083] In this embodiment of the ternary solid-state battery, the positive electrode is an 811 positive electrode sheet, the negative electrode is a lithium metal negative electrode, and the solid electrolyte located between the positive electrode and the negative electrode is the solid electrolyte prepared in Example 7. The above-mentioned positive electrode, solid electrolyte and negative electrode are assembled into a solid-state battery, and the battery cells are assembled in a stacked manner.

[0084] Example 18

[0085] In this embodiment of the ternary solid-state battery, the positive electrode is an 811 positive electrode sheet, the negative electrode is a lithium metal negative electrode, and the solid electrolyte located between the positive electrode and the negative electrode is the solid electrolyte prepared in Example 8. The above-mentioned positive electrode, solid electrolyte and negative electrode are assembled into a solid-state battery, and the battery cells are assembled in a stacked manner.

[0086] Example 19

[0087] In this embodiment of the ternary solid-state battery, the positive electrode is an 811 positive electrode sheet, the negative electrode is a lithium metal negative electrode, and the solid electrolyte located between the positive electrode and the negative electrode is the solid electrolyte prepared in Example 9. The above-mentioned positive electrode, solid electrolyte and negative electrode are assembled into a solid-state battery, and the battery cells are assembled in a stacked manner.

[0088] Example 20

[0089] In this embodiment of the ternary solid-state battery, the positive electrode is an 811 positive electrode sheet, the negative electrode is a lithium metal negative electrode, and the solid electrolyte located between the positive electrode and the negative electrode is the solid electrolyte prepared in Example 10. The above-mentioned positive electrode, solid electrolyte and negative electrode are assembled into a solid-state battery, and the battery cells are assembled in a stacked manner.

[0090] Example 21

[0091] In this embodiment of the ternary solid-state battery, the positive electrode is an 811 positive electrode sheet, the negative electrode is a lithium metal negative electrode, and the solid electrolyte located between the positive electrode and the negative electrode is the solid electrolyte prepared in Example 11. The above-mentioned positive electrode, solid electrolyte and negative electrode are assembled into a solid-state battery, and the battery cells are assembled in a stacked manner.

[0092] Example 22

[0093] In this embodiment of the ternary solid-state battery, the positive electrode is an 811 positive electrode sheet, the negative electrode is a lithium metal negative electrode, and the solid electrolyte located between the positive electrode and the negative electrode is the solid electrolyte prepared in Example 12. The above-mentioned positive electrode, solid electrolyte and negative electrode are assembled into a solid-state battery, and the battery cells are assembled in a stacked manner.

[0094] Comparative Example 2

[0095] In this embodiment of the ternary solid-state battery, the positive electrode is an 811 positive electrode sheet, the negative electrode is a lithium metal negative electrode, and the solid electrolyte located between the positive electrode and the negative electrode is the solid electrolyte prepared in Comparative Example 1. The above-mentioned positive electrode, solid electrolyte, and negative electrode are assembled into a solid-state battery, and the battery cells are assembled in a stacked manner.

[0096] Performance testing:

[0097] The present invention conducted performance tests on the ternary solid-state batteries obtained in Examples 13 to 22 and Comparative Example 2. The test methods adopted were existing technologies, and the results are shown in Table 1 below.

[0098] Table 1. Performance test results of solid-state batteries in Examples 13 to 22 and Comparative Example 2.

[0099]

[0100]

[0101] Table 1 shows that the upper limit of the electrochemical window for Examples 13-22 is higher than 4.8V, which is higher than that of the PEO-based solid-state battery (Comparative Example 2), demonstrating good electrochemical stability and adaptability to high-voltage cathode materials. In Examples 14 and 16, an additional coordinating group was added to the alkoxy chain, resulting in a corresponding increase in conductivity and ion transference number. In Examples 16 and 17, two coordinating groups were added to the alkoxy chain, leading to a significant increase in conductivity and ion transference number. In the solid electrolytes of Examples 18, 19, 20, and 21, inorganic nanoparticles and a plasticizer (succinate) were added. Since the inorganic nanoparticles can increase the strength of the electrolyte and the plasticizer can increase ionic conductivity, the conductivity and ion transference number are further increased. In the solid electrolyte of Example 22, an additional ionic liquid (1-butyl-1-methylpiperidine bis(trifluoromethanesulfonyl)imine salt) was added to the original plasticizer (succinate). Since the ionic liquid can also increase the ionic conductivity, it leads to an increase in conductivity and ion transport number.

[0102] In summary, the solid electrolyte involved in this invention, with lithium salt, stereoisotactic polyethylene ether, inorganic nanoparticles, and plasticizer as its main components, exhibits good room-temperature lithium-ion transport capability, high-voltage resistance, and stability to lithium metal.

[0103] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the field; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0104] While specific embodiments of the invention have been described in detail by way of examples, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of the invention. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.

Claims

1. A solid electrolyte, characterized in that, This solid electrolyte can withstand high voltages above 4.8V and comprises a polymer, a lithium salt, and additives dispersed in the polymer. The additives include inorganic nanoparticles, plasticizers, and ionic liquids. The polymer is a polyvinyl ether of one of formulas P1 to P7, and the polyvinyl ether is a stereoisotactic polymer with a number-average molecular weight of 1 × 10⁻⁶. 4 -6×10 4 ; ； Where m is a positive integer, Cy is cyclohexyl, iBu is isobutyl, nBu is n-butyl, and Bn is benzyl.

2. The solid electrolyte according to claim 1, characterized in that, The mass ratio of the polymer, the lithium salt, and the additive is 60%-75% : 10%-25% : 0%-15%.

3. The solid electrolyte according to claim 1, characterized in that, The inorganic nanoparticles are titanium dioxide and Li7La3Zr2O. 12 、Li7La3Zr 1.5 Ta 0.5 O 12 One of them.

4. The solid electrolyte according to claim 1, characterized in that, The plasticizer includes succinic anhydride.

5. The solid electrolyte according to claim 1, characterized in that, The ionic liquid includes piperidine salts.

6. The solid electrolyte according to claim 1, characterized in that, The lithium salt is at least one of lithium hexafluorophosphate, lithium perchlorate, lithium difluorooxalate borate, lithium bis(trifluoromethanesulfonyl)imide, and lithium bis(fluorosulfonyl)imide.

7. A method for preparing a solid electrolyte, used to prepare the solid electrolyte according to any one of claims 1 to 6, characterized in that, include: The polymer, lithium salt, and additives are obtained by mass fraction and dissolved in a volatile solvent to obtain a mixed solution; The mixed solution is evenly applied to the surface of the polytetrafluoroethylene sheet; Vacuum drying at 25℃-60℃ for 4-8 hours removes the volatile solvent, yielding a solid electrolyte.

8. A solid-state battery, characterized in that, The solid-state battery includes a positive electrode, a negative electrode, and a solid electrolyte located between the positive electrode and the negative electrode. The solid electrolyte is the solid electrolyte according to any one of claims 1 to 6, and the electrochemical window of the solid-state battery is greater than or equal to 4.8V.

9. The solid-state battery according to claim 8, characterized in that, The positive electrode includes a positive current collector and a positive electrode material coated on the surface of the positive current collector; the positive electrode material is composed of a ternary active material and an inorganic compound coated on the surface of the ternary active material.

10. The solid-state battery according to claim 9, characterized in that, The ternary active material is LiNi. 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.7 Co 0.1 Mn 0.2 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.8 Co 0.15 Al 0.05 O2 or LiNi 0.9 Co 0.05 Al 0.05 O2.

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