Solid electrolyte, preparation method thereof and solid-state battery

Abstract

The invention discloses a solid-state electrolyte and a preparation method thereof, and a solid-state battery, the solid-state electrolyte is prepared from a polymer, and a lithium salt and an additive dispersed in the polymer, the additive comprises inorganic nanoparticles, a plasticizer and an ionic liquid, the polymer is polyvinyl ether of one of formulas P1 to P7, the number-average molecular weight of the polymer is 1 * 10 < 4 >-10 * 10 < 4 >; wherein m is a positive integer, Cy is cyclohexyl, iBu is isobutyl, nBu is n-butyl, and Bn is benzyl. The adopted polyvinyl ether is a three-dimensional isotactic polymer, and a main chain and a side chain do not contain chemical groups (such as hydroxyl) of reactive hydrogen, so that the oxygenolysis tendency of the electrolyte under high pressure can be remarkably reduced, and an electrochemical window is remarkably improved. The electrochemical window of the solid-state battery is improved to 4.8 V or above.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and more specifically, to a solid electrolyte and a preparation method thereof, and a solid-state battery. Background Art

[0002] The rapid development of electric vehicles has placed higher demands on the safety and energy density of power batteries. Currently, lithium-ion batteries generally use flammable liquid electrolytes, which pose a high safety risk. Replacing the original liquid electrolyte with a solid-state electrolyte is an effective means of addressing lithium-ion battery safety issues. Solid-state lithium batteries are considered by the industry to be the next generation of high-energy-density, high-safety batteries with the greatest potential for widespread application.

[0003] Research on all-solid-state lithium batteries using PEO as a solid electrolyte is the most mature. However, PEO electrolytes have a low voltage window (less than 4.0V), limiting their use to lithium iron phosphate systems. To further increase the energy density of solid-state batteries, higher-capacity cathode materials are the preferred choice. Currently, high-nickel ternary materials are the most widely used high-capacity cathode materials.

[0004] Compared with lithium iron phosphate all-solid-state batteries, the preparation of high-nickel ternary all-solid-state batteries has the following difficulties: (1) The charging voltage of high-nickel ternary cathode materials is relatively high, generally at 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) The 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 metal lithium negative electrode.

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

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

[0007] In one aspect, the present invention provides a solid electrolyte, which is made of a polymer, a lithium salt dispersed in the polymer, and an additive, wherein the additive includes inorganic nanoparticles, a plasticizer, and an ionic liquid, and the polymer is a polyethylene ether of one of the following formulas P1 to P7, and the number average molecular weight of the polymer is 1×10 4 -10×10 4 ;

[0008]

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

[0010] The polymer in the present invention is polyvinyl ether, a stereoisotactic polymer with ether bonds in its structural units, capable of complexing and rapidly transferring metal lithium ions. The solid electrolyte can withstand high voltages exceeding 4.8V and is suitable for ternary systems with high electrolyte requirements.

[0011] The synthesis method of the polymer is a method in the prior art, for example, reference may be made to 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 the present invention is 1×10 4 -10×10 4 , optionally, 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 liquid and has poor moldability. The number average molecular weight of the polymer in the present invention is 1×10 4 -10×10 4 , good solubility and film-forming properties.

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

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

[0015] Optionally, the mass ratio of the polymer, lithium salt and additive can be: 75%:25%:0%, or 60%:25%:15%, or 70%:20%:10%, or 75%:15%:10%, or any value between 60%-75%:10%-25%:0%-15%, which is not specifically limited here.

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

[0017] In the present invention, Li7La3Zr2O 12 、Li7La3Zr 1.5 Ta 0.5 O 12 It has high ionic conductivity. After being compounded with polymers, it can not only reduce the cleanliness of the polymer matrix and improve the ionic conductivity, but also provide another ion transmission path, further improving the electrochemical performance of the composite electrolyte.

[0018] Optionally, the plasticizer includes succinonitrile.

[0019] Succinonitrile molecules have highly polar cyano groups that can interact with lithium salts, effectively dissociating them and promoting the transport of lithium ions. Succinonitrile can also improve interfacial stability. Succinonitrile molecules can interact with the electrode surface to form a stable interfacial layer and reduce interfacial impedance.

[0020] Optionally, the ionic liquid comprises a piperidinium salt.

[0021] Piperidinium salts have good thermal stability, high ionic conductivity, negligible vapor pressure and non-flammability, and can be used to improve the ionic conductivity of solid electrolytes.

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

[0023] On the other hand, the present invention also provides a method for preparing a solid electrolyte, which is used to prepare the above-mentioned solid electrolyte, comprising:

[0024] S1, obtaining a polymer, a lithium salt, and an additive according to mass fractions, and dissolving them in a volatile solvent to obtain a mixed solution;

[0025] S2, evenly coating the mixed solution on the surface of the polytetrafluoroethylene plate;

[0026] S3, vacuum drying at a temperature of 25° C. to 60° C. for 4 to 8 hours to remove the volatile solvent to obtain a solid electrolyte.

[0027] Alternatively, the volatile solvent may be tetrahydrofuran (THF).

[0028] Optionally, the vacuum drying temperature can be 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, or any value between 25°C and 60°C, and 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, 8 hours, or any value between 4 hours and 8 hours.

[0029] In a third aspect, 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, the solid electrolyte is the above-mentioned 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 electrode current collector and a positive electrode material coated on the surface of the positive electrode current collector; the positive electrode material is composed of a ternary active substance and an inorganic compound coated on the surface of the ternary active substance.

[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 and its preparation method, and the solid-state battery provided by the present invention achieve at least the following beneficial effects:

[0033] In the prior art, PEO is used to make solid electrolytes, which have active hydrogen groups. Active hydrogen groups have the risk of oxidative decomposition. For example, active hydrogen groups such as hydroxyl (-OH) are easily oxidized to carbonyl (C=O) or carboxyl (-COOH) at high voltage (>4.0V), and further react with lithium ions to generate by-products such as Li2CO3, leading to electrolyte decomposition and increased interfacial impedance; at the same time, active hydrogen groups will also cause the interface stability to decrease, and the oxidation products of active hydrogen groups will destroy the interface between the electrolyte and the electrode, triggering side reactions, thereby limiting the cycle life of the battery at high voltage.

[0034] The present invention uses polyvinyl ether as a stereoisotactic polymer. Neither the main chain nor the side chains of the polyvinyl ether contain active hydrogen chemical groups (such as hydroxyl groups), which significantly reduces the tendency of the electrolyte to oxidatively decompose under high pressure and significantly improves the electrochemical window. Furthermore, the polyvinyl ether replaces the hydroxyl groups in the main chain and side chains with inert groups, which reduces interfacial side reactions, lowers the internal resistance of the battery, and extends the cycle life.

[0035] The electrochemical window of the solid-state battery of the present invention is increased to above 4.8V.

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

[0037] Further features and advantages of the present invention will become apparent from the following detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0039] Figure 1 The present invention provides a flow chart of a method for preparing a solid electrolyte. DETAILED DESCRIPTION

[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 of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention.

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

[0042] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

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

[0044] It should be noted that like reference numerals and letters refer to like items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

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

[0046] Example 1

[0047] The method for preparing the solid electrolyte of this embodiment comprises the following steps:

[0048] The polymer (P1, M n =9.5×10 4 g / mol) and lithium hexafluorophosphate (LiPF6) are dissolved in tetrahydrofuran, with the mass percentages of P1 and LiPF6 being 75% and 25%, respectively. The solution is then evenly coated on a polytetrafluoroethylene plate and dried in a vacuum at 45°C for 6 hours to remove the tetrahydrofuran, thereby obtaining a solid electrolyte.

[0049] Example 2

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

[0051] Example 3

[0052] The polymer (P3, M n =9.2×10 4 g / mol) and lithium difluorooxalatoborate are dissolved in tetrahydrofuran, wherein the mass percentages of P3 and lithium difluorooxalatoborate are 75% and 25% respectively. The solution is then coated on a polytetrafluoroethylene plate and dried in a vacuum at 45°C for 6 hours to remove the tetrahydrofuran to obtain a solid electrolyte.

[0053] Example 4

[0054] The polymer (P4, M n =7.3×104 g / mol) and lithium bis(trifluoromethylsulfonyl imide) (TFSILi) were dissolved in tetrahydrofuran, with the mass percentages of P4 and TFSILi being 75% and 25% respectively. The solution was then coated onto a polytetrafluoroethylene plate and dried in a vacuum at 45°C for 6 hours to remove the tetrahydrofuran to obtain a solid electrolyte.

[0055] Example 5

[0056] The polymer (P5, M n =7.3×10 4 g / mol) and lithium bis(trifluoromethylsulfonyl imide) (LiTFSi) were dissolved in tetrahydrofuran, with the mass percentages of P5 and TFSILi being 75% and 25% respectively. The solution was then coated onto a polytetrafluoroethylene plate and dried in a vacuum at 45°C for 6 hours to remove the tetrahydrofuran to obtain a solid electrolyte.

[0057] Example 6

[0058] The polymer (P6, M n =5.6×10 4 g / mol) and lithium bis(fluorosulfonyl)imide (LiFSi) were dissolved in tetrahydrofuran, with the mass percentages of P6 and LiFSi being 75% and 25% respectively. The solution was then coated on a polytetrafluoroethylene plate and dried in a vacuum at 45°C for 6 hours to remove the tetrahydrofuran to obtain a solid electrolyte.

[0059] Example 7

[0060] The polymer (P7, M n =7.5×10 4 g / mol) and lithium bis(trifluoromethylsulfonyl)imide (LiTFSi) were dissolved in tetrahydrofuran, with the mass percentages of P7 and LiFSi being 75% and 25% respectively. The solution was then coated onto a polytetrafluoroethylene plate and dried in a vacuum at 45°C for 6 hours to remove the tetrahydrofuran to obtain a solid electrolyte.

[0061] Example 8

[0062] The polymer (P7, M n =7.8×10 4 g / mol), lithium bis(trifluoromethylsulfonyl)imide (LiTFSi), titanium dioxide, and succinonitrile are dispersed in tetrahydrofuran, where the mass percentages of P7, LiFSi, titanium dioxide, and succinonitrile are 60%, 25%, 7.5%, and 7.5%, respectively. The solution is then coated on a polytetrafluoroethylene plate and dried in a vacuum at 45°C for 6 hours to remove the tetrahydrofuran to obtain a solid electrolyte.

[0063] Example 9

[0064] The polymer (P7, M n =7.8×10 4 g / mol), lithium bis(trifluoromethylsulfonyl)imide (LiTFSi), titanium dioxide, and succinonitrile are dispersed in tetrahydrofuran, where the mass percentages of P7, LiFSi, titanium dioxide, and succinonitrile are 65%, 20%, 7.5%, and 7.5%, respectively. The solution is then coated on a polytetrafluoroethylene plate and dried in a vacuum at 45°C for 6 hours to remove the tetrahydrofuran to obtain a solid electrolyte.

[0065] Example 10

[0066] The polymer (P7, M n =7.8×10 4 g / mol), lithium bis(trifluoromethanesulfonyl)imide (LiTFSi), Li7La3Zr2O 12 , succinonitrile is dispersed in tetrahydrofuran, among which P7, LiFSi, Li7La3Zr2O 12 The mass percentages of succinonitrile are 60%, 25%, 7.5% and 7.5%. The solution is then coated on a polytetrafluoroethylene plate and dried in a vacuum at 45°C for 6 hours to remove tetrahydrofuran to obtain a solid electrolyte.

[0067] Example 11

[0068] The polymer (P7, M n =7.8×10 4 g / mol), lithium bis(trifluoromethanesulfonyl)imide (LiTFSi), Li7La3Zr 1.5 Ta 0.5 O 12 , succinonitrile is dispersed in tetrahydrofuran, among which P7, LiFSi, Li7La3Zr2O 12 The mass percentages of succinonitrile are 60%, 25%, 7.5% and 7.5%. The solution is then coated on a polytetrafluoroethylene plate and dried in a vacuum at 45°C for 6 hours to remove tetrahydrofuran to obtain a solid electrolyte.

[0069] Example 12

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

[0071] Comparative Example 1

[0072] PEO(M n =60×10 4 g / mol), lithium bis(trifluoromethanesulfonyl)imide (LiTFSi), titanium dioxide, succinonitrile, and 1-butyl-1-methylpiperidinium bis(trifluoromethanesulfonyl)imide are dispersed in tetrahydrofuran, wherein the mass percentages of PEO, LiFSi, titanium dioxide, succinonitrile, and 1-butyl-1-methylpiperidinium bis(trifluoromethanesulfonyl)imide are 60%, 25%, 7.5%, 3.75%, and 3.75%, respectively. The solution is then coated on a polytetrafluoroethylene plate and the tetrahydrofuran is removed by vacuum drying at 45°C for 6 hours to obtain a solid electrolyte.

[0073] The following Examples 13 to 22 are specific examples of ternary solid-state batteries, and the solid electrolyte in the solid-state battery of Comparative Example 2 is the solid-state electrolyte prepared in Comparative Example 1.

[0074] Example 13

[0075] The ternary solid-state battery of this embodiment has an 811 positive electrode plate as the positive electrode, a lithium metal negative electrode as the negative electrode, and a solid electrolyte prepared in Example 1 as the solid electrolyte between the positive and negative electrodes. The above-mentioned positive electrode, solid electrolyte, and negative electrode are assembled into a solid-state battery, and the battery core is assembled in a stacking manner.

[0076] Example 14

[0077] The ternary solid-state battery of this embodiment has an 811 positive electrode plate as the positive electrode, a lithium metal negative electrode as the negative electrode, and a solid electrolyte prepared in Example 2 as the solid electrolyte between the positive and negative electrodes. The above-mentioned positive electrode, solid electrolyte, and negative electrode are assembled into a solid-state battery, and the battery core is assembled in a stacking manner.

[0078] Example 15

[0079] The ternary solid-state battery of this embodiment has an 811 positive electrode plate as the positive electrode, a metallic lithium negative electrode as the negative electrode, and a solid electrolyte prepared in Example 4 as the solid electrolyte between the positive and negative electrodes. The above-mentioned positive electrode, solid electrolyte, and negative electrode are assembled into a solid-state battery, and the battery core is assembled in a stacking manner.

[0080] Example 16

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

[0082] Example 17

[0083] The ternary solid-state battery of this embodiment has an 811 positive electrode plate as the positive electrode, a metallic lithium negative electrode as the negative electrode, and a solid electrolyte prepared in Example 7 as the solid electrolyte between the positive and negative electrodes. The above-mentioned positive electrode, solid electrolyte, and negative electrode are assembled into a solid-state battery, and the battery core is assembled in a stacking manner.

[0084] Example 18

[0085] The ternary solid-state battery of this embodiment has an 811 positive electrode plate as the positive electrode, a metallic lithium negative electrode as the negative electrode, and a solid electrolyte prepared in Example 8 as the solid electrolyte between the positive and negative electrodes. The above-mentioned positive electrode, solid electrolyte, and negative electrode are assembled into a solid-state battery, and the battery core is assembled in a stacking manner.

[0086] Example 19

[0087] The ternary solid-state battery of this embodiment has an 811 positive electrode plate as the positive electrode, a lithium metal negative electrode as the negative electrode, and a solid electrolyte prepared in Example 9 as the solid electrolyte between the positive and negative electrodes. The above-mentioned positive electrode, solid electrolyte, and negative electrode are assembled into a solid-state battery, and the battery core is assembled in a stacking manner.

[0088] Example 20

[0089] The ternary solid-state battery of this embodiment has an 811 positive electrode plate as the positive electrode, a metallic lithium negative electrode as the negative electrode, and a solid electrolyte prepared in Example 10 as the solid electrolyte between the positive electrode and the negative electrode. The above-mentioned positive electrode, solid electrolyte, and negative electrode are assembled into a solid-state battery, and the battery core is assembled in a stacking manner.

[0090] Example 21

[0091] The ternary solid-state battery of this embodiment has an 811 positive electrode plate as the positive electrode, a metallic lithium negative electrode as the negative electrode, and a solid electrolyte prepared in Example 11 as the solid electrolyte between the positive electrode and the negative electrode. The above-mentioned positive electrode, solid electrolyte, and negative electrode are assembled into a solid-state battery, and the battery core is assembled in a stacking manner.

[0092] Example 22

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

[0094] Comparative Example 2

[0095] The ternary solid-state battery of this embodiment has an 811 positive electrode sheet as the positive electrode, a lithium metal negative electrode as the negative electrode, and the solid electrolyte 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 core is assembled in a stacking 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 testing method adopted the method of the prior art. The results are shown in Table 1 below.

[0098] Table 1 Solid-state battery performance test results of Examples 13 to 22 and Comparative Example 2

[0099]

[0100]

[0101] It can be concluded from Table 1 that the upper limits of the electrochemical windows of Examples 13-22 are all higher than 4.8V, which are higher than those of PEO-based solid-state batteries (Comparative Example 2), showing good electrochemical stability and being able to adapt to high-voltage positive electrode materials. In Example 14 and Example 16, a coordinating group is added to the alkoxy chain. Due to the additional addition of a coordinating group, the electrical conductivity and the ion migration number increase accordingly. In Example 16 and Example 17, two coordinating groups are added to the alkoxy chain, resulting in a substantial increase in electrical conductivity and ion migration number. Inorganic nanoparticles and plasticizers (succinonitrile) are added to the solid electrolytes of Example 18, Example 19, Example 20, and Example 21. Since inorganic nanoparticles can increase the strength of the electrolyte, plasticizers can increase ionic conductivity, thereby further increasing electrical conductivity and ion migration number. In the solid electrolyte of Example 22, an ionic liquid (1-butyl-1-methylpiperidinium bis(trifluoromethanesulfonyl)imide salt) is added to the original plasticizer (succinonitrile). Since the ionic liquid can also increase the ionic conductivity, it leads to an increase in the conductivity and the ion migration number.

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

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

[0104] Although some specific embodiments of the present invention have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present invention. It should be understood by those skilled in the art that modifications may be made to the above embodiments without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.

Claims

1. A solid electrolyte, characterized in that The invention comprises a polymer, a lithium salt and an additive dispersed in the polymer, wherein the additive comprises inorganic nanoparticles, a plasticizer and an ionic liquid, the polymer is a polyethylene ether of one of the following formulas P1 to P7, and the number average molecular weight of the polymer is 1×10 4 -6×10 4 ; Wherein, m is a positive integer, Cy is a cyclohexyl group, i Bu is isobutyl, n Bu 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, 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 succinonitrile.

5. The solid electrolyte according to claim 1, characterized in that The ionic liquids include piperidinium 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 difluorooxalatoborate, lithium bis(trifluoromethylsulfonyl)imide, and lithium bis(fluorosulfonyl)imide.

7. A method for preparing a solid electrolyte, for preparing the solid electrolyte according to any one of claims 1 to 6, characterized in that: include: obtaining a polymer, a lithium salt and an additive according to mass fractions, and dissolving them in a volatile solvent to obtain a mixed solution; Evenly coating the mixed solution on the surface of the polytetrafluoroethylene plate; The solid electrolyte is obtained by vacuum drying at a temperature of 25° C. to 60° C. for 4 to 8 hours to remove the volatile solvent.

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-state electrolyte is the solid-state 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 comprises a positive electrode current collector and a positive electrode material coated on the surface of the positive electrode current collector; the positive electrode material is composed of a ternary active substance and an inorganic compound coated on the surface of the ternary active substance.

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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