An organic mixed conductor, its preparation method and application

Abstract

The present invention provides an organic mixed conductor, a preparation method thereof and an application thereof. The organic mixed conductor comprises a lithium salt and poly(3-monomethoxypolyethylene glycol)thiophene represented by General Formula 1. The organic mixed conductor provided by the present invention has both good electronic and ionic conductivities and certain adhesiveness, and can replace polyvinylidene fluoride and conductive carbon in a traditional positive electrode to ensure the mass ratio of the positive electrode active material; by adjusting the side chain length and the degree of polymerization of the main chain of the poly(3-monomethoxypolyethylene glycol)thiophene represented by General Formula 1, the present invention can realize the modulation of the ionic and electronic conductivities of the organic mixed conductor, thereby preparing positive electrodes of solid-state lithium secondary batteries with different performances; compared with the traditional positive electrode of polyvinylidene fluoride / conductive carbon / positive electrode active material, the organic mixed conductor provided by the present invention for the positive electrode of the solid-state lithium secondary battery can significantly improve the cycling performance of the solid-state lithium secondary battery.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium batteries, and relates to an organic mixed conductor and its preparation method and application, specifically to an organic mixed conductor, its preparation method, a positive electrode sheet, and a solid-state lithium secondary battery. Background Art

[0002] For traditional liquid lithium-ion batteries, simply relying on the optimization of battery structure and preparation process is difficult to meet the social demand for energy storage devices with higher energy density and safety. Therefore, developing the next-generation battery chemical system has become the only way to prepare high-specific-energy and safe batteries. Among them, rechargeable lithium-metal batteries using metallic lithium as the negative electrode and paired with high-voltage positive electrode materials are considered to be one of the most promising high-energy-density energy storage devices. However, traditional electrolytes can cause lithium powdering and uncontrollably lead to the formation of lithium dendrites and dead lithium under electrochemical conditions. In contrast, solid-state lithium secondary batteries using solid electrolytes can well overcome the above problems. However, traditional positive electrode sheets prepared using polyvinylidene fluoride / conductive carbon / positive electrode active materials belong to solid-state porous electrodes. In liquid lithium-ion batteries, the positive electrode sheet can achieve good electron and ion transport due to the infiltration of the electrolyte. However, for solid-state lithium secondary batteries, the contact between the solid electrolyte and the positive electrode sheet is a solid-solid contact. Because the ionic conductivity of commonly used binders such as polyvinylidene fluoride is very low, except for the active material part in contact with the solid electrolyte on the surface layer of the positive electrode sheet, the lithium-ion transport of most of the active materials in its inner layer will face great difficulties, thereby affecting the overall performance of solid-state lithium secondary batteries. And the method of directly adding an ionic conductive agent to the original positive electrode slurry will not only reduce the mass ratio of the active material in the positive electrode sheet but also cannot ensure that the ionic conductivity of the positive electrode sheet can be significantly improved.

[0003] Therefore, for solid-state lithium secondary batteries, the component structure of their positive electrode sheets needs to be reconfigured. The goal of the reconfiguration is to simultaneously make the positive electrode sheet have higher ionic conductivity while ensuring the mass ratio of the active substance in the positive electrode sheet. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide an organic mixed conductor and its preparation method and application, specifically to provide an organic mixed conductor, its preparation method, a positive electrode sheet, and a solid-state lithium secondary battery. The organic mixed conductor provided by the present invention includes a poly(thiophene) polymer grafted with monomethoxy polyethylene glycol and a lithium salt. This organic mixed conductor has good ionic / electronic conductivity and good adhesion to the positive electrode active material and the current collector. Compared with traditional polyvinylidene fluoride / conductive carbon / positive electrode active materials, the solid-state lithium secondary battery assembled with the positive electrode sheet prepared from the organic mixed conductor / positive electrode active material has higher battery cycling performance.

[0005] To achieve this purpose, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides an organic mixed conductor, which includes a lithium salt and poly(3-monomethoxy polyethylene glycol)thiophene shown in General Formula 1:

[0007]

[0008] In General Formula 1, m is the number of repeating units in the polymer chain, and the value of m is an integer from 1 to 100 (such as 1, 3, 5, 8, 10, 13, 15, 18, 20, 23, 25, 28, 30, 33, 35, 38, 40, 43, 45, 48, 50, 53, 55, 58, 60, 63, 65, 68, 70, 73, 75, 78, 80, 83, 85, 88, 90, 93, 95, 98 or 100, etc.), and n is the number of ethoxy repeating units, and the value of n is an integer from 1 to 8 (such as 1, 2, 3, 4, 5, 6, 7 or 8).

[0009] The organic mixed conductor provided by the present invention not only has good electronic and ionic conductivities, but also has a certain adhesiveness, and can replace polyvinylidene fluoride and conductive carbon in the traditional positive electrode to ensure the mass ratio of the positive electrode active material; by adjusting the side chain length and the degree of polymerization of the main chain of poly(3-monomethoxy polyethylene glycol)thiophene shown in General Formula 1, the present invention can realize the modulation of the ionic and electronic conductivities of the organic mixed conductor, thereby preparing solid-state lithium secondary battery positive electrodes with different performances; compared with the traditional polyvinylidene fluoride / conductive carbon / positive electrode active material positive electrode, the organic mixed conductor provided by the present invention used in the solid-state lithium secondary battery positive electrode can significantly improve the cycle performance of the solid-state lithium secondary battery.

[0010] Preferably, the poly(3-monomethoxy polyethylene glycol)thiophene shown in General Formula 1 is a protonic acid-catalyzed polymerization product of 3-monomethoxy polyethylene glycol)thiophene monomers.

[0011] Preferably, the poly(3-monomethoxy polyethylene glycol)thiophene shown in General Formula 1 is prepared by the following preparation method:

[0012] (1) 3-Methoxythiophene reacts with oligomeric monomethoxy-capped polyethylene glycol to generate 3-monomethoxy polyethylene glycol)thiophene monomers;

[0013] (2) The 3-monomethoxy polyethylene glycol)thiophene monomers undergo a polymerization reaction to obtain the poly(3-monomethoxy polyethylene glycol)thiophene.

[0014] The preparation route is as follows:

[0015]

[0016] Preferably, the molar ratio of the 3-methoxythiophene to the oligomeric monomethoxy-capped polyethylene glycol in step (1) is 1:(1 - 4), such as 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, or 1:4, etc.

[0017] Preferably, the catalyst for the reaction in step (1) includes sodium bisulfate.

[0018] Preferably, the catalyst for the polymerization reaction in step (2) includes a protonic acid.

[0019] Preferably, the protonic acid includes any one or a combination of at least two of hydrogen chloride, sulfuric acid, nitric acid, formic acid, acetic acid, trifluoromethanesulfonic acid, p-toluenesulfonic acid, or heteropolyacid (such as phosphotungstic acid, etc.).

[0020] Preferably, n is an integer from 3 to 6.

[0021] Preferably, the lithium salt includes any one or a combination of at least two of lithium difluorophosphate (LiPF2O2), lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), lithium hexafluoroborate (LiBF6), lithium trifluoromethanesulfonate (LiCF3SO3), lithium hexafluoroarsenate (LiAsF6), lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), lithium bis(difluoromethylsulfonyl)imide (LiFSI), lithium bis(oxalato)borate (LiBOB), lithium difluoro(oxalato)borate (LiDFOB), or lithium malonate oxalate borate (LiMOB).

[0022] Preferably, the molar ratio of the lithium salt to the ethoxy group in the poly(3-monomethoxypolyethylene glycol)thiophene represented by the general formula 1 is 1:1 - 1:100, such as 1:1, 1:3, 1:5, 1:8, 1:10, 1:20, 1:30, 1:40, 1:50, 1:60, 1:70, 1:80, 1:90, or 1:100, etc.

[0023] In a second aspect, the present invention provides a method for preparing the organic mixed conductor described in the first aspect, and the preparation method includes the following steps:

[0024] Dissolve the poly(3-monomethoxypolyethylene glycol)thiophene represented by the general formula 1 in an organic solvent, then add a lithium salt, and remove the organic solvent to obtain the organic mixed conductor.

[0025] Preferably, the organic solvent includes chloroform.

[0026] Alternatively, mix the poly(3-monomethoxypolyethylene glycol)thiophene represented by the general formula 1 and a lithium salt, and perform solid-phase grinding to obtain the organic mixed conductor.

[0027] In a third aspect, the present invention provides a positive electrode sheet, which includes a current collector and a coating disposed on the current collector, and the material of the coating includes a positive electrode active material and an organic mixed conductor as described in the first aspect.

[0028] Preferably, the positive electrode active material contains any one or a combination of at least two of lithium, iron, cobalt, nickel, manganese, aluminum, or phosphorus elements, and the positive electrode active material is doped or coated with one or at least two elements selected from aluminum, magnesium, zirconium, titanium, scandium, lanthanum, nickel, manganese, yttrium, or strontium.

[0029] Preferably, the positive electrode active material includes any one or a combination of at least two of lithium iron phosphate (LFP), lithium manganese iron phosphate, lithium cobalt oxide (LCO), lithium manganese oxide, nickel cobalt manganese ternary electrode material (NCM111, 523, 622, 811), nickel cobalt aluminum ternary electrode material, or lithium-rich manganese-based material.

[0030] Preferably, based on the total weight of the positive electrode active material and the organic mixed conductor being 100%, the weight percentage of the organic mixed conductor is 2.5 - 40%, such as 2.5%, 5%, 8%, 10%, 15%, 18%, 20%, 25%, 28%, 30%, 35%, 38%, or 40%, etc.

[0031] Preferably, the positive electrode sheet is prepared by the following method:

[0032] Dissolve the organic mixed conductor in an organic solvent, then add the positive electrode active material to obtain a mixed slurry, coat the mixed slurry on the current collector, dry, and roll to obtain the positive electrode sheet.

[0033] Preferably, the organic solvent includes N-methylpyrrolidone.

[0034] Alternatively, mix the organic mixed conductor and the positive electrode active material, grind to obtain a grinding material, and compound the grinding material on the current collector to obtain the positive electrode sheet.

[0035] In a fourth aspect, the present invention provides a solid-state lithium secondary battery, which includes a positive electrode sheet, a solid electrolyte, and a negative electrode sheet, and the positive electrode sheet is the positive electrode sheet described in the third aspect.

[0036] Preferably, the solid electrolyte is selected from any one of polymer solid electrolytes, inorganic solid electrolytes, or organic-inorganic composite solid electrolytes.

[0037] Preferably, the active material of the negative electrode sheet includes any one or a combination of at least two of carbon-based materials, silicon-based materials, boron-based materials, metallic lithium, metallic bismuth, nitrides, magnesium-based alloys, transition metal oxides, or phosphides.

[0038] On the basis of conforming to the common knowledge in the art, the above-mentioned preferred conditions can be freely combined without exceeding the protection scope of the present invention.

[0039] Compared with the prior art, the present invention has at least the following beneficial effects:

[0040] (1) The present invention mainly solves the problem of ion transport between the porous solid cathode prepared from traditional polyvinylidene fluoride / conductive carbon / cathode active material and the solid electrolyte, which limits the areal loading of the cathode active material in the existing solid-state lithium secondary battery. The organic mixed conductor designed and synthesized in the present invention has both good electronic and ionic conductivities and certain adhesiveness, so it can replace polyvinylidene fluoride and conductive carbon in the traditional cathode to ensure the mass ratio of the cathode active material.

[0041] (2) By adjusting the side-chain length of poly(3-monomethoxy polyethylene glycol)thiophene shown in General Formula 1 and the degree of polymerization of the main chain, the present invention can realize the modulation of the ionic and electronic conductivities of the organic mixed conductor, thereby preparing solid-state lithium secondary battery cathodes with different performances.

[0042] (3) Compared with the traditional polyvinylidene fluoride / conductive carbon / cathode active material cathode, the organic mixed conductor designed and synthesized in the present invention for the solid-state lithium secondary battery cathode can significantly improve the cycle performance of the solid-state lithium secondary battery (initial cycle efficiency: 80.2%-87.5%; capacity retention rate after 300 cycles: 81%-91%). Specific Embodiments

[0043] The technical solution of the present invention will be further described below by specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0044] Example 1

[0045] In this example, an organic mixed conductor is provided, and the organic mixed conductor includes a lithium salt and poly(3-monomethoxy polyethylene glycol)thiophene shown as follows:

[0046]

[0047] The preparation method includes the following steps:

[0048] (1) Under a nitrogen atmosphere, 8 grams of 3-methoxythiophene was weighed and placed in a round-bottom flask, 50 milliliters of toluene was added and stirred to dissolve at room temperature. Subsequently, 17.2 grams of monomethoxytriglycol and 2.6 grams of sodium bisulfate were added to the solution, and the reaction solution was refluxed for 72 hours to obtain 11.7 grams of 3-monomethoxytriglycolylthiophene monomer.

[0049] (2) Take 6 g of 3 - monomethoxytriethylene glycol - based thiophene monomer, add 0.6 g of p - toluenesulfonic acid, react at room temperature for 24 h, and wash with methanol multiple times to obtain poly(3 - monomethoxytriethylene glycol - based) thiophene precipitate.

[0050] (3) Take 5 g of poly(3 - monomethoxytriethylene glycol - based) thiophene and dissolve it in 20 mL of chloroform, add 1.1 g of LiTFSI and stir, then remove the chloroform to obtain a dark - colored organic mixed conductor.

[0051] Example 2

[0052] In this example, an organic mixed conductor is provided, and the organic mixed conductor includes a lithium salt and poly(3 - monomethoxypolyethylene glycol - based) thiophene as shown below:

[0053]

[0054] The preparation method includes the following steps:

[0055] (1) Under a nitrogen atmosphere, weigh 8 g of 3 - methoxythiophene and place it in a round - bottom flask, add 70 mL of toluene and stir to dissolve at room temperature. Subsequently, add 21.8 g of monomethoxytetraethylene glycol and 3.0 g of sodium bisulfate to the solution, and reflux the reaction solution for 72 h to obtain 14.7 g of 3 - monomethoxytetraethylene glycol - based thiophene monomer.

[0056] (2) Take 6 g of 3 - monomethoxytetraethylene glycol - based thiophene monomer, add 0.6 g of trifluoromethanesulfonic acid, react at room temperature for 24 h, and wash with methanol multiple times to obtain a dark - colored precipitate of poly(3 - monomethoxytetraethylene glycol - based) thiophene.

[0057] (3) Take 5 g of poly(3 - monomethoxytetraethylene glycol - based) thiophene and dissolve it in 35 mL of chloroform, add 1.5 g of LiFSI and stir, then remove the chloroform to obtain a dark - colored organic mixed conductor.

[0058] Example 3

[0059] In this example, an organic mixed conductor is provided, and the organic mixed conductor includes a lithium salt and poly(3 - monomethoxypolyethylene glycol - based) thiophene as shown below:

[0060]

[0061] The preparation method includes the following steps:

[0062] (1) Under a nitrogen atmosphere, weigh 4 g of 3 - methoxythiophene and place it in a round - bottom flask, add 80 mL of toluene and stir to dissolve at room temperature. Subsequently, add 15.5 g of monomethoxyhexethylene glycol and 2.0 g of sodium bisulfate to the solution, and reflux the reaction solution for 72 h to obtain 9.3 g of 3 - monomethoxyhexethylene glycol - based thiophene monomer.

[0063] (2) Take 5 g of 3-monomethoxy hexaglycolylthiophene monomer, add 0.5 g of phosphotungstic acid, react at room temperature for 24 h, and wash with methanol multiple times to obtain poly(3-monomethoxy hexaglycolyl)thiophene precipitate.

[0064] (3) Take 5 g of poly(3-monomethoxy hexaglycolyl)thiophene and dissolve it in 45 mL of chloroform, add 1.1 g of LiDFOB and stir, then remove the chloroform to obtain a dark organic mixed conductor.

[0065] Comparative Example 1

[0066] The difference between this comparative example and Example 1 is only that is replaced with an equimolar amount of

[0067] Comparative Example 2

[0068] The difference between this comparative example and Example 1 is only that is replaced with an equimolar amount of

[0069] Application Examples 1-8

[0070] A positive electrode plate, the positive electrode plate includes a current collector (aluminum foil) and a coating provided on the current collector, the material of the coating includes a positive electrode active material and the organic mixed conductor provided in Examples 1-3, and the positive electrode active material, the organic mixed conductor used in Application Examples 1-8, and, based on the total weight of the positive electrode active material and the organic mixed conductor being 100%, the weight percentage of the organic mixed conductor is specifically shown in Table 1.

[0071] The preparation methods of the positive electrode plates provided in Application Examples 1-8 are shown in Table 1.

[0072] Table 1

[0073]

[0074] In Table 1, (1) The slurry mixing and coating method specifically includes the following steps: dissolve the organic mixed conductor in N-methylpyrrolidone, then add the positive electrode active material to obtain a mixed slurry, coat the mixed slurry on the current collector, and perform vacuum drying and rolling to obtain the positive electrode plate. (2) The mixed grinding method specifically includes the following steps: mix the organic mixed conductor and the positive electrode active material and grind to obtain a grinding material, and compound the grinding material on the current collector to obtain the positive electrode plate. (3) The inorganic solid electrolyte is LLZTO, and the polymer solid electrolyte is poly(ethylene oxide) (PEO).

[0075] In Application Examples 1 - 8, a solid - state lithium secondary battery is also provided respectively, which includes a positive electrode sheet, a solid electrolyte, and a negative electrode sheet. The positive electrode sheet and the solid electrolyte are as shown in Table 1 respectively. The preparation method of the solid - state lithium secondary battery is as follows:

[0076] (1) Positive electrode sheet: As shown in Table 1;

[0077] (2) Solid electrolyte: As shown in Table 1;

[0078] (3) Negative electrode sheet: A lithium metal sheet with a thickness of 0.25 mm;

[0079] (4) Assembly of the solid - state lithium secondary battery: Assemble the prepared positive electrode sheet, solid electrolyte, and negative electrode sheet into a 5 Ah soft - pack battery (the negative electrode and the positive electrode are paired and assembled according to N / P = 1.1).

[0080] Comparative Application Example 1

[0081] The difference between this comparative application example and Application Example 1 is only that the organic mixed conductor provided in Example 1 is replaced by polyvinylidene fluoride and conductive carbon with the same weight percentage (85%) (where the weight ratio of polyvinylidene fluoride to conductive carbon is 1:1.7).

[0082] Comparative Application Example 2

[0083] The difference between this comparative application example and Application Example 3 is only that the organic mixed conductor provided in Example 2 is replaced by polyvinylidene fluoride and conductive carbon with the same weight percentage (85%) (where the weight ratio of polyvinylidene fluoride to conductive carbon is 1:1.8).

[0084] Comparative Application Example 3

[0085] The difference between this comparative application example and Application Example 5 is only that the organic mixed conductor provided in Example 3 is replaced by polyvinylidene fluoride and conductive carbon with the same weight percentage (85%) (where the weight ratio of polyvinylidene fluoride to conductive carbon is 1.1.6).

[0086] Comparative Application Example 4

[0087] The difference between this comparative application example and Application Example 1 is only that the organic mixed conductor provided in Example 1 is replaced by the organic mixed conductor provided in Comparative Example 1.

[0088] Comparative Application Example 5

[0089] The difference between this comparative application example and Application Example 1 is only that the organic mixed conductor provided in Example 1 is replaced by the organic mixed conductor provided in Comparative Example 2.

[0090] Perform performance tests on the solid-state lithium secondary batteries provided by the application examples and comparative application examples. The test method is as follows: The battery adopts a constant current-constant potential charging / constant current discharging mode. The charging and discharging cut-off voltages are 4.20 V and 2.75 V respectively. The cut-off current of the constant potential is 0.02 C. Leave it standing for 30 minutes between the charging and discharging of each cycle. The battery is cycled at a charging and discharging rate of 0.1 C / 0.5 C at 60 °C.

[0091] The performance test results are shown in Table 2.

[0092] Table 2

[0093] First-week efficiency (%) Capacity retention rate after 300 cycles (%) Application Example 1 86.5 91 Application Example 2 85.7 89 Application Example 3 84.3 87 Application Example 4 87.2 85 Application Example 5 85.7 86 Application Example 6 83.5 85 Application Example 7 80.2 81 Application Example 8 87.5 90 Comparative Application Example 1 72.6 76 Comparative Application Example 2 70.5 73 Comparative Application Example 3 67.3 64 Comparative Application Example 4 71.4 65 Comparative Application Example 5 78.5 75

[0094] As can be seen from Table 2, the solid-state lithium secondary batteries provided by Application Examples 1-8 of the present invention all have a relatively high first-week efficiency (80.2%-87.5%) and a 300-cycle capacity retention rate (81%-91%).

[0095] Through the comparison between Application Example 1 and Comparative Application Example 1, Application Example 3 and Comparative Application Example 2, and Application Example 5 and Comparative Application Example 3, it can be seen that the organic mixed conductor provided by the present invention can significantly improve the cycling performance of the solid-state lithium secondary battery.

[0096] Compared with Application Example 1, the first-week efficiency and the 300-cycle capacity retention rate of the solid-state lithium secondary batteries provided by Comparative Application Examples 4-5 have both decreased significantly.

[0097] The applicant declares that the present invention uses the above-mentioned embodiments to illustrate the organic mixed conductor of the present invention, its preparation method and application. However, the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned embodiments to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent substitution of each raw material of the product of the present invention, the addition of auxiliary components, the selection of specific methods, etc., all fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A positive electrode sheet, characterized in that, The positive electrode plate includes a current collector and a coating disposed on the current collector, and the material of the coating is composed of a positive electrode active material and an organic mixed conductor; The organic mixed conductor includes a lithium salt and poly(3-monomethoxy polyethylene glycol)thiophene shown in General Formula 1: In General Formula 1, m is an integer with a value of 1-100, and n is an integer with a value of 3-6; Based on the total weight of the positive electrode active material and the organic mixed conductor being 100%, the weight percentage of the organic mixed conductor is 15-20%.

2. The positive electrode sheet according to claim 1, characterized in that, The poly(3-monomethoxy polyethylene glycol)thiophene shown in General Formula 1 is a protonic acid-catalyzed polymerization product of 3-monomethoxy polyethylene glycol thiophene monomers.

3. The positive electrode sheet according to claim 1, wherein The poly(3-monomethoxy polyethylene glycol)thiophene shown in General Formula 1 is prepared by the following preparation method: (1) 3-Methoxythiophene reacts with oligomeric monomethoxy-capped polyethylene glycol to generate 3-monomethoxy polyethylene glycol thiophene monomers; (2) The 3-monomethoxy polyethylene glycol thiophene monomers undergo a polymerization reaction to obtain the poly(3-monomethoxy polyethylene glycol)thiophene.

4. The organic hybrid conductor according to claim 3, characterized in that, In step (1), the molar ratio of 3-methoxythiophene to oligomeric monomethoxy-capped polyethylene glycol is 1:(1-4).

5. The organic hybrid conductor according to claim 3, wherein The catalyst for the reaction in step (1) includes sodium bisulfate.

6. The organic hybrid conductor according to claim 3, characterized in that, The catalyst for the polymerization reaction in step (2) includes a protonic acid.

7. The organic mixed conductor according to claim 6, characterized in that, The protonic acid includes any one or a combination of at least two of hydrogen chloride, sulfuric acid, nitric acid, formic acid, acetic acid, trifluoromethanesulfonic acid, p-toluenesulfonic acid, or heteropolyacid.

8. The organic hybrid conductor according to claim 1, characterized in that, The lithium salt includes any one or a combination of at least two of lithium difluorophosphate, lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroborate, lithium trifluoromethanesulfonate, lithium hexafluoroarsenate, lithium bis(trifluoromethylsulfonyl)imide, lithium bis(difluoromethanesulfonyl)imide, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, or lithium malonate oxaloborate.

9. The organic mixed conductor according to claim 1, wherein, The molar ratio of the lithium salt to the ethoxy group in the poly(3-monomethoxy polyethylene glycol)thiophene shown in General Formula 1 is 1:1-1:

100.

10. The positive electrode sheet according to claim 1, characterized in that, The preparation method of the organic mixed conductor includes the following steps: Dissolve the poly(3-monomethoxy polyethylene glycol)thiophene shown in General Formula 1 in an organic solvent, then add a lithium salt, and remove the organic solvent to obtain the organic mixed conductor; Or, mix the poly(3-monomethoxy polyethylene glycol)thiophene shown in General Formula 1 and a lithium salt, and perform solid-phase grinding to obtain the organic mixed conductor.

11. The positive electrode sheet according to claim 1, characterized in that, The positive electrode active material includes any one or a combination of at least two of lithium iron phosphate, lithium manganese iron phosphate, lithium cobaltate, lithium manganate, nickel cobalt manganese ternary electrode material, nickel cobalt aluminum ternary electrode material, or lithium-rich manganese-based material.

12. The positive electrode sheet according to claim 1, characterized in that, The positive electrode plate is prepared by the following method: Dissolve the organic mixed conductor in an organic solvent, then add the positive electrode active material to obtain a mixed slurry, coat the mixed slurry on the current collector, dry, and roll to obtain the positive electrode plate; Or, mix the organic mixed conductor and the positive electrode active material, grind to obtain a grinding material, and compound the grinding material on the current collector to obtain the positive electrode plate.

13. A solid-state lithium secondary battery, comprising a positive electrode sheet, a solid electrolyte, and a negative electrode sheet, characterized in that, The positive electrode plate is the positive electrode plate according to any one of claims 1-12.

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