Quasi-solid-state battery and its preparation method

Abstract

A preparation method of a quasi-solid-state battery, comprising the following steps: adding a first solvent to a first solid electrolyte at 180°C to 185°C to prepare a composite solid electrolyte; coating the composite solid electrolyte on a positive composite sheet and a negative composite sheet respectively to prepare a solid electrolyte composite positive sheet and a solid electrolyte composite negative sheet; injecting an electrolyte solution between the solid electrolyte composite positive sheet and the solid electrolyte composite negative sheet to prepare the quasi-solid-state battery; the mass ratio of the first solid electrolyte to the first solvent is 85 to 90:10 to 15; the preparation raw materials of the positive composite sheet include a positive active material; the addition amount of the electrolyte solution and the mass ratio of the positive active material is 8 to 20:80 to 92. The preparation method of the quasi-solid-state battery of the present invention can enable the solid electrolyte to better seal the positive composite sheet and the negative composite sheet, reduce the interfacial resistance, improve the cycling performance of the battery core, reduce the electrolyte content, and improve the battery safety performance.

Description

Technical Field

[0001] The present invention relates to the technical field of battery preparation, and particularly to a method for preparing a quasi-solid-state battery. Background Art

[0002] Traditional lithium-ion batteries use organic liquids as electrolytes for lithium-ion transmission. The liquid electrolyte is usually distributed between the positive and negative electrode particles and in the pores of the separator, and an ion channel is constructed through the liquid electrolyte. This liquid electrolyte is often a highly volatile and flammable organic solvent type, posing a huge safety hazard to the battery, and is also prone to generating lithium dendrites, accelerating battery failure. Solid-state lithium batteries use all-solid-state electrolytes to replace the separator and electrolyte in traditional batteries, and lithium-ion transmission is carried out through the all-solid-state electrolyte to construct an ion channel. However, the interfacial resistance between the solid electrolyte and the positive electrode particles, between the solid electrolyte and the negative electrode particles, and between the solid electrolytes is relatively large, and the ionic conductivity of the solid electrolyte ions is not as good as that of the liquid electrolyte, and the cycle performance of the battery cell is not good.

[0003] For the quasi-solid-state batteries prepared by the existing technical routes at present, a method of coexisting solid electrolytes and liquid electrolytes is adopted. At this time, the solid electrolyte and the liquid electrolyte are distributed between the positive and negative electrode particles, and the liquid electrolyte is distributed in the gaps of the solid electrolyte film to construct an ion channel. However, it is very difficult to reduce the amount of the liquid electrolyte in this state of coexistence of the solid electrolyte and the liquid electrolyte, because there are gaps between the solid electrolyte and the positive electrode particles, between the solid electrolyte and the negative electrode particles, and between the solid electrolytes, and the liquid electrolyte will penetrate in, which is not much different from a fully liquid battery, with a relatively high safety hazard, and the interfacial resistance between the solid electrolyte and the positive electrode particles, between the solid electrolyte and the negative electrode particles, and between the solid electrolytes is still very high, and the cycle performance of the battery cell is not good. Summary of the Invention

[0004] Based on this, it is necessary to provide a method for preparing a quasi-solid-state battery, which appropriately reduces the content of the electrolyte, enables the solid electrolyte to better seal the positive and negative electrode materials, reduces the gaps, reduces the interfacial resistance, and improves the cycle performance of the battery cell.

[0005] In the first aspect of the present invention, a method for preparing a quasi-solid-state battery is provided, including the following steps:

[0006] At 180°C to 185°C, a first solvent is added to a first solid electrolyte to prepare a composite solid electrolyte; the composite solid electrolyte solution is respectively coated on a positive electrode composite sheet and a negative electrode composite sheet to prepare a solid electrolyte composite positive electrode sheet and a solid electrolyte composite negative electrode sheet; an electrolyte is injected between the solid electrolyte composite positive electrode sheet and the solid electrolyte composite negative electrode sheet to prepare the quasi-solid-state battery.

[0007] In one embodiment, the mass ratio of the first solid electrolyte to the first solvent is 85 to 90:10 to 15.

[0008] In one embodiment, the preparation raw materials of the positive electrode composite sheet include a positive electrode active material.

[0009] In one embodiment, the mass ratio of the addition amount of the electrolyte solution to the mass of the positive electrode active material is 8 to 20:80 to 92.

[0010] In one embodiment, the first solvent is poly-1,3-dioxolane.

[0011] In one embodiment, the first solid electrolyte is selected from one of sulfide solid electrolytes and oxide solid electrolytes.

[0012] In one embodiment, the sulfide solid electrolyte is selected from one of Li 10 GeP2S 12 、Li2S-P2S5, and Li2S-SiS2.

[0013] In one embodiment, the oxide solid electrolyte is selected from one of Li 1.3 Si 0.225 V 1.36 (PO4)3, Li 0.34 La 0.51 TiO 2.94 、Li7La3Zr2O 12 and so on.

[0014] In one embodiment, the preparation method of the positive electrode composite sheet includes:

[0015] Mix the positive electrode active material, the second solid electrolyte, and the conductive agent, sinter the obtained mixture to prepare positive electrode composite particles; add the second solvent at 180°C to 185°C to make the mass ratio of the positive electrode composite particles to the second solvent 91 to 99:1 to 9 to prepare a positive electrode composite particle solution; use the positive electrode composite particle solution to coat a positive electrode current collector to prepare a positive electrode composite sheet.

[0016] In one embodiment, the positive electrode active material is selected from one of LiCoO2, NCM 811, and NCA ternary materials.

[0017] In one embodiment, the conductive agent is selected from one of graphene, conductive carbon black, carbon nanotubes, Ketjen black, and conductive graphite.

[0018] In one embodiment, the second solid electrolyte is selected from one of sulfide solid electrolytes and oxide solid electrolytes.

[0019] In one embodiment, the second solvent is poly(1,3-dioxolane).

[0020] In one embodiment, the mass ratio of the positive electrode active material, the second solid electrolyte, and the conductive agent is 85-95:4-14:1, respectively.

[0021] In one embodiment, the parameters of the sintering step include:

[0022] The sintering temperature is 900°C ± 5°C, and the sintering time is 2h ± 0.5h.

[0023] In one embodiment, the method for preparing the negative electrode composite sheet includes:

[0024] Coating a negative electrode current collector with a negative electrode active material to prepare a negative electrode composite sheet.

[0025] In one embodiment, the negative electrode active material is selected from one of graphite, silicon-carbon, and metallic lithium.

[0026] In the second aspect of the present invention, a quasi-solid-state battery is prepared by using the method for preparing the quasi-solid-state battery described above.

[0027] Compared with the traditional scheme, the present invention has the following beneficial effects:

[0028] For the quasi-solid-state battery prepared by the present invention, by controlling the mass ratio of the first solid electrolyte to the first solvent and the melting temperature of the first solvent, the first solid electrolyte can better seal the positive electrode composite sheet and the negative electrode composite sheet, eliminating the interfacial resistance between the solid electrolyte and the positive electrode composite sheet, and between the solid electrolyte and the negative electrode composite sheet. By controlling the mass ratio of the added amount of the electrolyte solution to the positive electrode active material to be 8-20:80-92, the interfacial resistance between the solid electrolytes is eliminated, the growth of lithium dendrites is prevented, the safety performance of the quasi-solid-state battery is improved, and the cell cycle performance of the quasi-solid-state battery is improved. Description of the Drawings

[0029] Figure 1 Schematic diagram of positive electrode composite particles of one embodiment, 101 - positive electrode active material, 102 - second solid electrolyte, 103 - conductive agent;

[0030] Figure 2 Schematic diagram of a composite solid electrolyte of one embodiment, 201 - poly(1,3-dioxolane), 202 - first solid electrolyte;

[0031] Figure 3Schematic diagram of the preparation method of a solid electrolyte composite positive electrode sheet for an embodiment, 301 - positive electrode composite sheet, 302 - composite solid electrolyte, 303 - positive electrode current collector;

[0032] Figure 4 Schematic diagram of the preparation method of a quasi - solid - state battery for an embodiment, 401 - positive electrode current collector, 402 - positive electrode composite sheet, 403 - composite solid electrolyte, 404 - negative electrode current collector, 405 - negative electrode composite sheet, 406 - composite solid electrolyte, 407 - electrolyte. Specific embodiments

[0033] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. Preferred embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs. The terms used in the description of the present invention in this specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0035] Term

[0036] Unless otherwise stated or there is a contradiction, the terms or phrases used herein have the following meanings:

[0037] In the present invention, the selection scope related to "and / or", "or / and", "and / or" includes any one of two or more related listed items, and also includes any and all combinations of the related listed items. The said any and all combinations include combinations of any two related listed items, any more related listed items, or all related listed items. It should be noted that when at least three items are connected by at least two conjunctive combinations selected from "and / or", "or / and", "and / or", it should be understood that this technical solution undoubtedly includes the technical solution connected by "logical AND", and also undoubtedly includes the technical solution connected by "logical OR". For example, "A and / or B" includes three parallel solutions: A, B, and A + B. Another example, the technical solution of "A, and / or, B, and / or, C, and / or, D" includes any one of A, B, C, D (that is, the technical solution connected by "logical OR"), and also includes any and all combinations of A, B, C, D, that is, it includes combinations of any two or any three of A, B, C, D, and also includes the four-item combination of A, B, C, D (that is, the technical solution connected by "logical AND").

[0038] In the present invention, regarding "multiple", "diverse", "multiple times", "multiple elements", etc., if there is no special limitation, it means greater than or equal to 2 in quantity. For example, "one or more" means one or greater than or equal to two.

[0039] In the present invention, "its combination", "any combination thereof", "any combination mode thereof", etc. include all suitable combination modes of any two or more than two of the listed items.

[0040] In the present invention, for "suitable combination mode", "suitable mode", "any suitable mode", etc., the "suitable" described therein is subject to being able to implement the technical solution of the present invention, solve the technical problems of the present invention, and achieve the expected technical effects of the present invention.

[0041] In the present invention, "preferred", "better", "more preferable", "as appropriate" are only used to describe the implementation modes or embodiments with better effects. It should be understood that they do not constitute a limitation to the protection scope of the present invention.

[0042] In the present invention, "further", "even further", "especially", etc. are used for descriptive purposes, indicating differences in content, but should not be understood as a limitation to the protection scope of the present invention.

[0043] In the present invention, "optionally", "optional", "optional" mean that it can be either present or absent, that is, it refers to any one of the two parallel solutions of "present" or "absent". If "optional" appears multiple times in a technical solution, without special instructions and without contradictions or mutual restrictions, each "optional" is independent of each other.

[0044] In the present invention, in relation to "the first aspect", "the second aspect", "the third aspect", "the fourth aspect", etc., the terms "first", "second", "third", "fourth", etc. are only for descriptive purposes and cannot be construed as indicating or implying relative importance or quantity, nor can they be construed as implicitly specifying the importance or quantity of the indicated technical features. Moreover, "first", "second", "third", "fourth", etc. only serve the purpose of non-exhaustive listing and description and should be understood not to constitute a closed limitation on quantity.

[0045] In the present invention, among the technical features described in an open-ended manner, it includes both a closed technical solution composed of the listed features and an open technical solution containing the listed features.

[0046] In the present invention, in relation to a numerical interval (i.e., a numerical range), unless otherwise specified, the selectable numerical values are considered continuous within the above numerical interval and include the two numerical endpoints (i.e., the minimum value and the maximum value) of the numerical range, as well as each numerical value between these two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to integers within the numerical interval, it includes the two endpoint integers of the numerical range, as well as each integer between the two endpoints. In this article, it is equivalent to directly listing each integer. For example, when t is an integer selected from 1 to 10, it means that t is any integer selected from the integer group composed of 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10. In addition, when multiple ranges are provided to describe features or characteristics, these ranges can be combined. In other words, unless otherwise specified, the ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.

[0047] For the temperature parameter in the present invention, unless otherwise specified, it allows both constant temperature treatment and variation within a certain temperature interval. It should be understood that the so-called constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. It is allowed to fluctuate within a range such as ±5°C, ±4°C, ±3°C, ±2°C, ±1°C.

[0048] In the present invention, in relation to the percentage content, unless otherwise specified, for solid-liquid mixing and solid-solid mixing, it refers to the mass percentage, and for liquid-liquid mixing, it refers to the volume percentage.

[0049] In the present invention, in relation to the percentage concentration, unless otherwise specified, it all refers to the final concentration. The so-called final concentration refers to the proportion of the added component in the system after adding this component.

[0050] In the first aspect of the present invention, a method for preparing a quasi-solid-state battery is provided, including the following steps:

[0051] At 180 °C to 185 °C, a first solvent is added to the first solid electrolyte to prepare a composite solid electrolyte; the composite solid electrolyte is respectively coated on the positive composite sheet and the negative composite sheet to prepare a solid electrolyte composite positive sheet and a solid electrolyte composite negative sheet; an electrolyte solution is injected between the solid electrolyte composite positive sheet and the solid electrolyte composite negative sheet to prepare the quasi-solid-state battery.

[0052] Optionally, the mass ratio of the first solid electrolyte to the first solvent is 85 to 90:10 to 15.

[0053] Optionally, the mass ratio of the addition amount of the electrolyte solution to the positive active material is 8 to 20:80 to 92.

[0054] Preferably, the first solvent is poly-1,3-dioxolane.

[0055] Optionally, the first solid electrolyte is selected from one of sulfide solid electrolytes and oxide solid electrolytes.

[0056] Optionally, the sulfide solid electrolyte is selected from one of Li 10 GeP2S 12 、Li2S-P2S5, and Li2S-SiS2;

[0057] Optionally, the oxide solid electrolyte is selected from one of Li 1.3 Si 0.225 V 1.36 (PO4)3, Li 0.34 La 0.51 TiO 2.94 、Li7La3Zr2O 12 among others.

[0058] Optionally, the coating step includes: using the spraying method, at a temperature of 180 °C to 185 °C, a stirring speed of 300 R / min to 500 R / min, a stirring time of 20 min to 40 min, and a spray gun pressure of 7 N to 9 N.

[0059] Optionally, the method for preparing the positive composite sheet includes:

[0060] Mixing the positive active material, the second solid electrolyte, and the conductive agent, sintering the resulting mixture to prepare positive composite particles; adding a second solvent at 180 °C to 185 °C, such that the mass ratio of the positive composite particles to the second solvent is 91 to 99:1 to 9, to prepare a positive composite particle solution; using the positive composite particle solution to coat the positive current collector to prepare the positive composite sheet.

[0061] Optionally, the positive electrode active material is selected from one of LiCoO2, NCM 811, and NCA ternary materials.

[0062] Optionally, the conductive agent is selected from one of graphene, conductive carbon black, carbon nanotubes, Ketjen black, and conductive graphite.

[0063] Optionally, the second solid electrolyte is selected from one of sulfide solid electrolytes and oxide solid electrolytes.

[0064] Preferably, the second solvent is poly(1,3-dioxolane).

[0065] Optionally, the mass ratio of the positive electrode active material, the second solid electrolyte, and the conductive agent is 85-95:4-14:1, respectively.

[0066] Optionally, the parameters of the sintering step include:

[0067] The sintering temperature is 900°C ± 5°C, and the sintering time is 2h ± 0.5h.

[0068] Optionally, the average particle size of the positive electrode composite particles is 10μm ± 0.5μm.

[0069] Preferably, the coating method of the positive electrode composite sheet is double-sided coating, and the coating amount is 442mg / cm 2 .

[0070] Optionally, the coating step of the positive electrode composite sheet includes: using the spraying method, the temperature is 180°C - 185°C, the stirring speed is 300R / min - 500R / min, the stirring time is 20min - 40min, and the spray gun pressure is 7N - 9N.

[0071] Optionally, when preparing the positive electrode composite sheet, after coating, a rolling step is further included.

[0072] Optionally, the thickness of the positive electrode composite sheet is 133μm ± 5μm.

[0073] Preferably, the positive electrode current collector is aluminum foil.

[0074] Optionally, the preparation method of the negative electrode composite sheet includes:

[0075] Coating the negative electrode current collector with the negative electrode active material to prepare the negative electrode composite sheet.

[0076] Optionally, the negative electrode active material is selected from one of graphite, silicon-carbon, and metallic lithium.

[0077] Optionally, the coating method of the negative electrode composite sheet is double-sided coating, and the single-sided coating thickness is 5μm ± 0.1μm.

[0078] Optionally, the coating step of the negative electrode composite sheet includes: using magnetron sputtering method, the magnetron sputtering power is 4.5 kW ± 0.1 kW, and the magnetron sputtering vacuum degree is 5×10 -3 Pa.

[0079] Preferably, the negative electrode current collector is copper foil.

[0080] In the second aspect of the present invention, a quasi-solid-state battery is prepared by using the preparation method of the quasi-solid-state battery.

[0081] The following are specific examples.

[0082] Example 1

[0083] Example 1 provides a method for manufacturing a quasi-solid-state battery, including the following steps:

[0084] 1. Method for manufacturing a solid electrolyte composite positive electrode sheet

[0085] (a) Preparation of positive electrode composite particles:

[0086] Mix the positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1 O2, the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 (PO4)3, and the conductive agent graphene by ball milling in a mass ratio of 90:9:1. After sintering at 900 °C for 2 h, the sintered material is crushed and sieved using a 200-mesh sieve to obtain positive electrode composite particles with an average particle size of 10 μm.

[0087] (b) Preparation of positive electrode composite sheet:

[0088] Mix the above positive electrode composite particles and poly-1,3-dioxolane by ball milling at 180 °C in a mass ratio of 95:5 to melt the poly-1,3-dioxolane. Then, using the spraying method (the specific process conditions of the spraying method are: temperature 180 °C, stirring speed 300 R / min, stirring time 20 min, spray gun pressure: 8 N), coat the above slurry evenly on both sides of the aluminum foil according to a coating amount of 442 mg / cm 2 After drying, rolling treatment is carried out to obtain a positive electrode composite sheet with a thickness of 133 μm;

[0089] (c) Preparation of solid electrolyte composite positive electrode sheet:

[0090] The oxide solid electrolyte Li 1.3 Si 0.225 V 1.36(PO4)3 and poly(1,3-dioxolane) are ball-milled and mixed at a mass ratio of 90:10 at 180 °C to melt the poly(1,3-dioxolane). Then, using the spraying method (the specific process conditions of the spraying method are: temperature 180 °C, stirring speed 300 R / min, stirring time 20 min, spray gun pressure: 8 N), it is uniformly coated on both sides of the positive composite sheet. The single-sided coating thickness is 3 μm, and the double-sided coating thickness is 6 μm.

[0091] 2. Method for fabricating a solid electrolyte composite negative electrode sheet:

[0092] (a) Preparation of a lithium metal composite negative electrode sheet:

[0093] Using a copper foil as the substrate, hanging it on the pay-off reel, after the lithium metal is excited, it is uniformly magnetron sputtered onto the copper foil. The thickness of the single-sided lithium metal coating is 5 μm. During the magnetron sputtering process, the magnetron sputtering power is 4.5 kW, the magnetron sputtering vacuum degree is 5×10 - 3 Pa, and the distance between the target and the substrate is 40 mm. After completing the coating on the first side of the copper foil substrate, the coating on the second side of the copper foil is carried out. The thickness of the double-sided lithium metal coating is 10 μm, and the completed negative electrode sheet is wound up.

[0094] (b) Preparation of a solid electrolyte composite lithium metal negative electrode sheet:

[0095] The oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 (PO4)3 and poly(1,3-dioxolane) are ball-milled and mixed at a mass ratio of 90:10 at 180 °C to melt the poly(1,3-dioxolane). Then, using the spraying method (the specific process conditions of the spraying method are: temperature 180 °C, stirring speed 300 R / min, stirring time 20 min, spray gun pressure: 8 N), it is uniformly coated on both sides of the lithium metal sheet. The single-sided coating thickness is 3 μm, and the double-sided coating thickness is 6 μm.

[0096] 3. Battery assembly and injection of liquid electrolyte:

[0097] In this example, the positive and negative electrode sheets are wound and assembled into a core, and then put into a shell to make a 1254 button cell. The injection amount of the electrolyte is 0.02 g, and the mass ratio of the positive active material to the injection amount of the electrolyte is 92:8.

[0098] 4. Test the battery performance of the sealed cell.

[0099] Example 2

[0100] The preparation method of Example 2 is basically the same as that of Example 1, except that: during the battery assembly process of Example 2, when injecting the electrolyte, the injection amount of the electrolyte is 0.03 g, and the mass ratio of the positive active material to the injection amount of the electrolyte is 88:12.

[0101] Example 3

[0102] The preparation method of Example 3 is basically the same as that of Example 1, except that: during the battery assembly process of Example 3, when injecting the electrolyte, the injection amount is 0.04 g, and the mass ratio of the positive electrode active material to the injection amount is 84:16.

[0103] Example 4

[0104] The preparation method of Example 4 is basically the same as that of Example 1, except that: during the battery assembly process of Example 4, when injecting the electrolyte, the injection amount is 0.05 g, and the mass ratio of the positive electrode active material to the injection amount is 80:20.

[0105] Example 5

[0106] The preparation method of Example 5 is basically the same as that of Example 1, except that: when preparing the composite solid electrolyte, the mass ratio of the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 (PO4)3 to poly-1,3-dioxolane is 85:15.

[0107] Example 6

[0108] The preparation method of Example 6 is basically the same as that of Example 2, except that: when preparing the composite solid electrolyte, when the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 (PO4)3 is mixed with poly-1,3-dioxolane, the melting temperature is 185 °C.

[0109] Comparative Example 1

[0110] The preparation method of Comparative Example 1 is basically the same as that of Example 1, except that: during the battery assembly process of Comparative Example 1, no electrolyte is injected after the battery assembly.

[0111] Comparative Example 2

[0112] The preparation method of Comparative Example 2 is basically the same as that of Example 1, except that: during the battery assembly process of Comparative Example 2, when injecting the electrolyte, the injection amount is 0.01 g, and the mass ratio of the positive electrode active material to the injection amount of the electrolyte is 96:4.

[0113] Comparative Example 3

[0114] The preparation method of Comparative Example 3 is basically the same as that of Example 1, except that: when preparing the composite solid electrolyte, the oxide solid electrolyte Li1.3 Si 0.225 V 1.36 (PO4)3 and poly(1,3 - dioxolane) have a mass ratio of 95:5.

[0115] Comparative Example 4

[0116] The preparation method of Comparative Example 4 is basically the same as that of Example 2, except that: when preparing the composite solid electrolyte, the molten temperature is 175 °C when the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 (PO4)3 and poly(1,3 - dioxolane) are mixed.

[0117] Electrochemical performance test

[0118] 1. Use a battery internal resistance tester to measure the internal resistance of the button cell.

[0119] 2. Measure the specific capacity of the button cell (specific capacity = capacity of the button cell / weight of the electrode material) under a current density of 0.5C.

[0120] 3. Charge and discharge the button cell 50 cycles under a current density of 0.5C to test the cycle performance of the button cell.

[0121] 4. Charge and discharge the button cell under a current density of 0.5C to test the number of cycles when the capacity retention rate of the button cell reaches 80%.

[0122] The recorded results of the internal resistance and capacity of the button cells in the electrochemical performance tests of the quasi - solid - state batteries prepared in Examples 1 - 6 and Comparative Examples 1 - 4 are shown in Table 1 below:

[0123] Table 1

[0124]

[0125] The recorded results of the capacity retention rate of the button cells and the contact surface condition between the solid electrolyte membrane and the positive electrode sheet in the quasi - solid - state batteries prepared in Examples 1 - 6 and Comparative Examples 1 - 4 are shown in Table 2 below:

[0126] Table 2

[0127]

[0128] As can be seen from Table 1 and Table 2 above:

[0129] The first - week specific capacity of Comparative Example 1 is relatively low and the battery internal resistance is relatively high because no electrolyte is added and the interfacial resistance between the solid - electrolyte composite lithium - metal positive electrode sheet and the solid - electrolyte composite lithium - metal negative electrode sheet is relatively high.

[0130] The first-week specific capacity of Comparative Example 2 was relatively low, the internal resistance of the battery was relatively high, and the cycling performance of the battery cell was relatively poor. This was because the mass ratio of the positive active material to the injection amount of the electrolyte was 96:4, and the injection amount of the electrolyte was too small, increasing the interfacial resistance.

[0131] The first-week specific capacity of Comparative Example 3 was relatively low, and the internal resistance of the battery was relatively high. This was because the gaps in the solid electrolyte membrane were not completely filled with poly(1,3-dioxolane), and the electrolyte penetrated into the composite of the solid electrolyte and the positive electrode or the composite of the solid electrolyte and the negative electrode from the gaps, resulting in insufficient electrolyte between the solid electrolyte composite lithium metal positive electrode sheet and the solid electrolyte composite lithium metal negative electrode sheet, increasing the interfacial resistance.

[0132] The first-week specific capacity of Comparative Example 4 was relatively low, and the internal resistance of the battery was relatively high. This was because the melting temperature of poly(1,3-dioxolane) was too low and it did not melt completely. Therefore, the combination of poly(1,3-dioxolane) and Li 1.3 Si 0.225 V 1.36 (PO4)3 was not tight enough, the gaps in the solid electrolyte membrane were not completely filled with poly(1,3-dioxolane), and the electrolyte penetrated into the solid electrolyte, the positive electrode composite sheet and the negative electrode composite sheet from the gaps, resulting in insufficient electrolyte between the solid electrolyte composite lithium metal positive electrode sheet and the solid electrolyte composite lithium metal negative electrode sheet, increasing the interfacial resistance and the cycling performance of the battery cell was not good.

[0133] In Examples 1 to 6, when the mass ratio of the addition amount of the electrolyte to the positive active material was 85-90:10-15, and the mass ratio of Li 1.3 Si 0.225 V 1.36 (PO4)3 and poly(1,3-dioxolane) was 85-90:10-15, and the melting temperature was 180°C - 185°C, a quasi-solid-state battery was prepared. For this quasi-solid-state battery, under the condition of 0.5C charge and discharge, the first-week specific capacity of the positive electrode material was increased, there was no lithium dendrite powder on the contact surface between the solid electrolyte membrane and the positive electrode sheet. After 50 cycles, the growth rate of the internal resistance of the battery was not higher than 2.21%, and the number of cycles with a cell capacity retention rate of 80% was not less than 434 cycles.

[0134] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0135] The above-described embodiments merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A preparation method of a quasi-solid-state battery, characterized in that, It includes the following steps: At 180°C to 185°C, add a first solvent to a first solid electrolyte to prepare a composite solid electrolyte; coat the composite solid electrolyte on a positive composite sheet and a negative composite sheet respectively to prepare a solid electrolyte composite positive sheet and a solid electrolyte composite negative sheet; inject an electrolyte solution between the solid electrolyte composite positive sheet and the solid electrolyte composite negative sheet to prepare the quasi-solid-state battery; The mass ratio of the first solid electrolyte to the first solvent is 85 to 90:10 to 15; The preparation method of the positive composite sheet includes: Mix a positive active material, a second solid electrolyte and a conductive agent, sinter the obtained mixture to prepare positive composite particles; add a second solvent at 180°C to 185°C, and make the mass ratio of the positive composite particles to the second solvent be 91 to 99:1 to 9 to prepare a positive composite particle solution; use the positive composite particle solution to coat a positive current collector to prepare a positive composite sheet; The addition amount of the electrolyte solution and the mass ratio of the positive active material is 8 to 20:80 to 92; The first solvent is poly(1,3-dioxolane), and the second solvent is poly(1,3-dioxolane).

2. The preparation method according to claim 1, wherein The first solid electrolyte is selected from one of sulfide solid electrolytes and oxide solid electrolytes; the sulfide solid electrolyte is selected from one of Li 10 GeP2S 12 , Li2S-P2S5, and Li2S-SiS2; the oxide solid electrolyte is selected from one of Li 1.3 Si 0.225 V 1.36 (PO4)3, Li 0.34 La 0.51 TiO 2.94 , Li7La3Zr2O 12 .

3. The preparation method according to claim 1, characterized in that, The positive active material is selected from one of LiCoO₂, NCM811 and NCA ternary materials; the conductive agent is selected from one of graphene, conductive carbon black, carbon nanotubes and conductive graphite; the second solid electrolyte is selected from one of sulfide solid electrolytes and oxide solid electrolytes.

4. The preparation method according to claim 3, wherein The conductive carbon black includes Ketjen black.

5. The preparation method according to claim 1, characterized in that, The mass ratios of the positive active material, the second solid electrolyte and the conductive agent are 85 to 95:4 to 14:1 respectively.

6. The preparation method according to claim 1, characterized in that, The parameters of the sintering step include: The sintering temperature is 900°C ± 10°C, and the sintering time is 2h ± 0.5h.

7. The preparation method according to claim 1, characterized in that, The preparation method of the negative composite sheet includes: Use a negative active material to coat a negative current collector to prepare a negative composite sheet.

8. The preparation method according to claim 7, characterized in that, The negative active material is selected from one of graphite, silicon carbon and metallic lithium.

9. A quasi-solid-state battery, characterized in that, It is made by using the preparation method according to any one of claims 1 to 8.

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