A solid electrolyte battery based on an unevenly coated solid electrolyte layer and a preparation method thereof

Abstract

The present invention discloses a solid electrolyte battery based on an unevenly coated solid electrolyte layer and a preparation method thereof, belonging to the technical field of lithium-ion batteries. The solid electrolyte battery is composed of a positive electrode sheet, a double-layer solid electrolyte layer and a negative electrode sheet from bottom to top. The double-layer solid electrolyte layer is composed of a solid electrolyte layer of the positive electrode and a solid electrolyte layer of the negative electrode from bottom to top. Both the solid electrolyte layer of the positive electrode and the solid electrolyte layer of the negative electrode have a structure that is thin in the middle and thick on both sides, and the thicknesses on both sides are symmetrically distributed, and the edges gradually thicken from the center to both sides. This electrolyte layer is an unevenly coated electrolyte layer, which fills the gaps in the thinned areas on both sides of the positive and negative electrodes, making the positive electrode sheet, the solid electrolyte layer and the negative electrode sheet fully fit, thereby improving the interfacial impedance between the electrode and the electrolyte and making the cycle performance of the all-solid-state battery better.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium - ion batteries, and particularly relates to a solid - state electrolyte battery based on an unevenly coated solid - state electrolyte layer and a preparation method thereof. Background Art

[0002] In the production process of solid - state batteries, there is a production method in the form of laminating the positive electrode, electrolyte layer, and negative electrode. Due to the solid - solid interface of the solid - state electrolyte, it is necessary to be in close contact with the positive and negative electrode foils to ensure the smooth transmission of lithium ions and reduce the internal resistance. However, during the coating process of the positive and negative electrodes, in order to prevent problems such as over - pressing, wavy edges, and edge explosion caused by uneven thickness in the coated area and the empty foil area during the rolling process, the two sides of the coating direction during the coating process of the positive and negative electrodes are usually thinned. The thinning treatment at the edges of the positive and negative electrode foils will cause the middle solid - state electrolyte layer to be unable to be in close contact with the electrode foils, increasing the difficulty of lithium - ion transmission and the battery impedance, thus affecting the performance of the battery core.

[0003] In the actual production process, only the assembled electrode core is pressurized after the lamination is completed. However, this pressurization only fits the central flat area and cannot cover the two - side thinned areas, resulting in an unevenly - fitted solid - state electrolyte - electrode foil interface, leading to uneven current flow and uneven resistance, affecting the performance of the battery core; and after the electrode core is assembled, the head of the electrode core is prone to uneven thickness of the battery core due to the thinning problem, affecting the assembly. Summary of the Invention

[0004] In order to overcome problems such as the increase in impedance caused by interface separation during the charge - discharge process in the prior art, the present invention provides a solid - state electrolyte battery based on an unevenly coated solid - state electrolyte layer and a preparation method thereof. The electrolyte layer is an unevenly coated electrolyte layer that fills the gaps in the thinned areas on both sides of the positive and negative electrodes, making the positive electrode foil, solid - state electrolyte layer, and negative electrode foil completely fit, thereby improving the interfacial impedance between the electrode and the electrolyte, making the cycle performance of the all - solid - state battery better and the thickness consistency of the electrode core higher.

[0005] The present invention is realized through the following technical solutions:

[0006] A solid - state electrolyte battery based on an unevenly coated solid - state electrolyte layer is composed of a positive electrode foil 5, a double - layer solid - state electrolyte layer, and a negative electrode foil 6 from bottom to top. The double - layer solid - state electrolyte layer is composed of a solid - state electrolyte layer 3 of the positive electrode and a solid - state electrolyte layer 1 of the negative electrode from bottom to top; both the solid - state electrolyte layer 3 of the positive electrode and the solid - state electrolyte layer 1 of the negative electrode have a structure that is thin in the middle and thick on both sides, and the thicknesses on both sides are symmetrically distributed, and the edges gradually thicken from the center to both sides.

[0007] Furthermore, the positive electrode foil 5 has a structure that is thick in the middle and thin on both sides, and is matched and fitted with the structure of the solid - state electrolyte layer 3 of the positive electrode;

[0008] The negative electrode sheet 6 has a structure that is thicker in the middle and thinner at both sides, and is matched and adhered to the structure of the solid electrolyte layer 1 of the negative electrode.

[0009] Furthermore, the length L1 of the thickened regions at both sides of the solid electrolyte layer 3 of the positive electrode and the solid electrolyte layer 1 of the negative electrode is 5 - 20 mm, the increased thickness H1 of the thickened regions at both ends of the solid electrolyte layer 3 of the positive electrode compared to the central region is 5 - 25 μm, and the increased thickness H2 of the thickened regions at both ends of the solid electrolyte layer 1 of the negative electrode compared to the central region is 3 - 20 μm.

[0010] On the other hand, the present invention also provides a method for preparing a solid electrolyte battery based on an unevenly coated solid electrolyte layer, comprising the following steps:

[0011] Step S1: Prepare a solid electrolyte coating substrate;

[0012] Step S2: Coat the slurry of the solid electrolyte onto the surface of the substrate prepared in Step S1, and then dry it, so as to form a solid electrolyte layer with different coating thicknesses on the substrate, wherein the thickness of the solid electrolyte layer of the positive electrode is less than the thickness of the solid electrolyte layer of the negative electrode;

[0013] Step S3: Separate the solid electrolyte layer of the positive electrode and the solid electrolyte layer of the negative electrode in Step S2 from the substrate respectively, and attach the side close to the substrate of the solid electrolyte layer of the positive electrode and the solid electrolyte layer of the negative electrode to each other to form a double-layer solid electrolyte layer;

[0014] Step S4: Assemble in the order of the positive electrode sheet, the solid electrolyte layer of the positive electrode of the double-layer solid electrolyte layer, the solid electrolyte layer of the negative electrode of the double-layer solid electrolyte layer, and the negative electrode sheet;

[0015] Step S5: Perform hot pressing or cold pressing treatment on the assembled electrode group to form a tightly adhered solid electrolyte battery.

[0016] Furthermore, the solid electrolyte coating substrate described in Step S1 is a metal thin sheet such as copper foil, aluminum foil, nickel foil, or a non-metal film such as polytetrafluoroethylene or polyvinyl chloride.

[0017] Furthermore, forming a solid electrolyte layer with different coating thicknesses on the substrate in Step S2 specifically means that the solid electrolyte layer has a structure that is thinner in the middle and thicker at both sides, the thicknesses at both sides are symmetrically distributed, and the edge gradually thickens from the center to both sides.

[0018] Furthermore, the solid electrolyte described in Step S2 is a polymer solid electrolyte or a sulfide electrolyte.

[0019] Furthermore, the coating method of the slurry of the solid electrolyte described in Step S2 is extrusion coating or gravure coating.

[0020] Further, the material of the positive electrode sheet described in step S4 includes, but is not limited to, one or a mixture of several materials such as nickel-cobalt-manganese ternary material, lithium iron phosphate material, lithium manganese iron phosphate material, lithium cobalt oxide material, lithium nickel oxide material, lithium manganese oxide material, lithium titanate material, etc.

[0021] Further, the material of the negative electrode sheet described in step S4 includes, but is not limited to, one or a mixture of several materials such as graphite material, lithium titanate material, silicon-containing negative electrode material, and lithium metal negative electrode material.

[0022] Compared with the prior art, the advantages of the present invention are as follows:

[0023] (1) The thinning area of the electrode sheet of the solid electrolyte battery based on uneven coating of the solid electrolyte layer in the present invention fits more closely with the solid electrolyte layer, and the contact resistance is significantly reduced.

[0024] (2) The life of the all-solid-state battery prepared by the method of the present invention is significantly improved;

[0025] (3) After cycling, the thickness of the electrode core of the all-solid-state battery prepared by the method of the present invention is more uniform, which is convenient for assembly. Description of the Drawings

[0026] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0027] Figure 1 It is a schematic diagram of the solid electrolyte layer corresponding to the negative electrode surface;

[0028] Figure 2 It is a schematic diagram of the solid electrolyte layer corresponding to the positive electrode surface;

[0029] Figure 3 It is a schematic diagram of the double-layer fitting of the solid electrolyte layer;

[0030] Figure 4 It is a schematic diagram of the composition of the solid electrolyte layer and the electrode sheet;

[0031] Figure 5 It is a schematic diagram of the solid electrolyte battery;

[0032] Figure 6 It is a schematic diagram of taking eight points in sequence from top to bottom in the height direction of the electrode core;

[0033] In the figure: the solid electrolyte layer 1 of the negative electrode, the first substrate 2, the solid electrolyte layer 3 of the positive electrode, the second substrate 4, the positive electrode plate 5, and the negative electrode plate 6. Detailed implementation mode

[0034] To clearly and completely describe the technical solution of the present invention and its specific working process, in combination with the accompanying drawings of the specification, the specific implementation mode of the present invention is as follows:

[0035] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0036] A solid electrolyte battery based on an unevenly coated solid electrolyte layer of the present invention is composed of a positive electrode plate 5, a double-layer solid electrolyte layer, and a negative electrode plate 6 from bottom to top. The double-layer solid electrolyte layer is composed of the solid electrolyte layer 3 of the positive electrode and the solid electrolyte layer 1 of the negative electrode from bottom to top; both the solid electrolyte layer 3 of the positive electrode and the solid electrolyte layer 1 of the negative electrode have a structure that is thin in the middle and thick on both sides, and the thicknesses on both sides are symmetrically distributed, and the edges gradually thicken from the center to both sides.

[0037] The positive electrode plate 5 has a structure that is thick in the middle and thin on both sides, and is matched and adhered to the structure of the solid electrolyte layer 3 of the positive electrode;

[0038] The negative electrode plate 6 has a structure that is thick in the middle and thin on both sides, and is matched and adhered to the structure of the solid electrolyte layer 1 of the negative electrode.

[0039] The thickness H3 of the solid electrolyte layer 3 of the positive electrode and the solid electrolyte layer 1 of the negative electrode is 20 - 200 um;

[0040] The length of the thickened regions on both sides of the solid electrolyte layer 3 of the positive electrode and the solid electrolyte layer 1 of the negative electrode is 5 - 20 mm. The thickness H1 increased in the thickened regions at both ends of the solid electrolyte layer 3 of the positive electrode compared with the central region is 5 - 25 um, and the thickness H2 increased in the thickened regions at both ends of the solid electrolyte layer 1 of the negative electrode compared with the central region is 3 - 20 um.

[0041] The present invention also provides a preparation method for a solid electrolyte battery based on an unevenly coated solid electrolyte layer, which includes the following steps:

[0042] Step S1: Prepare a substrate for solid electrolyte coating;

[0043] Step S2: Coat the slurry of the solid electrolyte onto the surface of the substrate prepared in Step S1, and then dry it, so as to form solid electrolyte layers with different coating thicknesses on the substrate. Among them, the thickness of the solid electrolyte layer of the positive electrode is less than that of the solid electrolyte layer of the negative electrode;

[0044] Step S3: Separate the solid electrolyte layer of the positive electrode and the solid electrolyte layer of the negative electrode in Step S2 from the substrate respectively, and attach the solid electrolyte layer of the positive electrode and the solid electrolyte layer of the negative electrode to each other on the side close to the substrate to form a double-layer solid electrolyte layer;

[0045] Step S4: Assemble in the order of the positive electrode sheet, the solid electrolyte layer of the positive electrode of the double-layer solid electrolyte layer, the solid electrolyte layer of the negative electrode of the double-layer solid electrolyte layer, and the negative electrode sheet;

[0046] Step S5: Perform hot pressing or cold pressing treatment on the assembled electrode group to form a tightly adhered solid electrolyte battery.

[0047] The substrate for solid electrolyte coating described in Step S1 is a metal thin sheet such as copper foil, aluminum foil, nickel foil, or a non-metal film such as polytetrafluoroethylene or polyvinyl chloride.

[0048] Forming solid electrolyte layers with different coating thicknesses on the substrate in Step S2 specifically means that the solid electrolyte layer has a structure that is thin in the middle and thick on both sides, and the thicknesses on both sides are symmetrically distributed, and the edge gradually thickens from the center to both sides.

[0049] The solid electrolyte described in Step S2 is a polymer solid electrolyte or a sulfide electrolyte.

[0050] The coating method of the slurry of the solid electrolyte described in Step S2 is extrusion coating or gravure coating.

[0051] The materials of the positive electrode sheet described in Step S4 include, but are not limited to, one or a mixture of several materials such as nickel-cobalt-manganese ternary materials, lithium iron phosphate materials, lithium manganese iron phosphate materials, lithium cobaltate materials, lithium nickelate materials, lithium manganate materials, and lithium titanate materials.

[0052] The materials of the negative electrode sheet described in Step S4 include, but are not limited to, one or a mixture of several materials such as graphite materials, lithium titanate materials, silicon-containing negative electrode materials, and lithium metal negative electrode materials.

[0053] Example 1

[0054] This embodiment provides a solid-state electrolyte battery based on an unevenly coated solid-state electrolyte layer, which is composed of a positive electrode sheet 5, a double-layer solid-state electrolyte layer, and a negative electrode sheet 6 from bottom to top. The double-layer solid-state electrolyte layer is composed of a solid-state electrolyte layer 3 of the positive electrode and a solid-state electrolyte layer 1 of the negative electrode from bottom to top. Both the solid-state electrolyte layer 1 of the negative electrode and the solid-state electrolyte layer 3 of the positive electrode have a structure that is thin in the middle and thick on both sides. The thicknesses on both sides are symmetrically distributed, and the edges gradually thicken from the center to both sides. The thickness changes on both sides correspond to the thinned areas on both sides of the negative electrode sheet and the positive electrode sheet respectively.

[0055] Among them, the thickness of the central region of the solid-state electrolyte layer 1 of the negative electrode is H3 = 50 μm, the thickness increase in the two end thickening regions compared with the central region is H2 = 3 μm, and the length of the two side thickening regions is L1 = 5 mm. The thickness of the central region of the solid-state electrolyte layer 3 of the positive electrode is H3 = 50 μm, the thickness increase in the two end thickening regions compared with the two side thickening regions is H1 = 5 μm, and the length of the two side thickening regions is L2 = 10 mm. After the solid-state electrolyte layer is dried, it is peeled off from the first substrate 2 and the second substrate 4 to form the solid-state electrolyte layer 1 of the negative electrode and the solid-state electrolyte layer 3 of the positive electrode. The corresponding substrate sides of the solid-state electrolyte layer 1 of the negative electrode and the solid-state electrolyte layer 3 of the positive electrode are bonded to form a double-layer solid-state electrolyte layer, as Figure 3 .

[0056] Comparative Example 1

[0057] This comparative example provides a solid-state electrolyte battery based on an unevenly coated solid-state electrolyte layer, corresponding to Example 1. Among them, the unevenly coated solid-state electrolyte layer is a single-layer structure, without distinguishing the corresponding positive and negative electrode sheets. The corresponding electrode side has a structure that is thin in the middle and thick on both sides. The thicknesses on both sides are symmetrically distributed, and the edges gradually thicken from the center to both sides. While the corresponding other electrode side is flat without thickness change, and the overall thickness is 60 μm. Comparative Example 2 This comparative example provides a solid-state electrolyte battery based on an unevenly coated solid-state electrolyte layer, corresponding to Example 1. Among them, the unevenly coated solid-state electrolyte layer is a single-layer structure, without distinguishing the corresponding positive and negative electrode sheets, without thickness change, and the overall thickness is 60 μm.

[0058] The performance test results of Example 1 and Comparative Examples 1-2 are as follows:

[0059] ACR test method: The test conditions are as follows: Under open circuit potential, the frequency range is 100 kHz - 0.1 Hz, the amplitude is 50 mV, and the impedance size of the solid-state lithium battery is measured. The test results are shown in Table 1.

[0060] DCR test method: The test conditions are as follows: At 25°C, the SOC of the battery cell is adjusted to 50%, and it is discharged with a 2C current I. Record the initial discharge voltage as V1 and the final discharge voltage as V2. DCR = (V1 - V2) / I. The test results are shown in Table 1;

[0061] Cyclic test method: The test conditions are as follows: Under the condition of 25 ± 1 °C, the batteries in the examples and comparative examples are charged at a constant current of 0.05C until the cut-off voltage is 4.2V, then left standing for 5 minutes; discharged at a constant current of 0.1C until the voltage reaches 2.5V; and the batteries are cycled for charge and discharge in this way until the discharge capacity reaches 80% of the initial capacity. The test results are shown in Table 1.

[0062] Table 1 is the performance test table of Example 1 and the comparative examples.

[0063] ACR / mohm DCR / mohm Cycle / Round Example 1 0.95 1.58 550 Comparative Example 1 1.15 1.67 420 Comparative Example 2 1.27 1.74 350

[0064] It can be seen from Table 1 that compared with the solid electrolyte batteries of Comparative Example 1 and Comparative Example 2, the contact resistance of the solid electrolyte battery of Example 1 with an unevenly coated solid electrolyte layer is significantly reduced, and the reduction rate can reach 10%. The life of the all-solid-state battery is also significantly improved.

[0065] Test method for the thickness of the assembled battery cell: Use a micrometer to measure the thickness at eight points from top to bottom in the height direction of the electrode core, as Figure 6 shown, and the test results are shown in Table 2.

[0066] Table 2 is the thickness test table of Example 1 and the comparative examples.

[0067] Position 1 / mm Position 2 / mm Position 3 / mm Position 4 / mm Position 5 / mm Position 6 / mm Position 7 / mm Position 8 / mm Example 1 11.8 11.7 11.8 11.9 11.8 11.8 12.0 12.2 Comparative Example 1 11.2 11.8 11.7 12.0 12.1 11.9 11.7 12.3 Comparative Example 2 10.5 11.8 11.9 12.2 12.1 11.9 12.0 12.1

[0068] It can be seen from Table 2 that compared with Comparative Example 1 and Comparative Example 2, for the all-solid-state battery of the present invention, the thicknesses at various positions in the height direction of the electrode core of Example 1 are basically the same, the electrode core thickness is more uniform, and the fitting between the thinned area of the electrode sheet and the solid electrolyte layer will be closer. (In Example 1, due to the closer fitting between the thinned area of the electrode sheet and the solid electrolyte layer, the thickness of the electrode core near the tab side is basically the same as the thicknesses at other positions, and the electrode core thickness is more uniform.)

[0069] Example 2:

[0070] This example provides a solid electrolyte battery based on an unevenly coated solid electrolyte layer, which is composed of a positive electrode sheet 5, a double-layer solid electrolyte layer, and a negative electrode sheet 6 from bottom to top. The double-layer solid electrolyte layer is composed of a solid electrolyte layer 3 of the positive electrode and a solid electrolyte layer 1 of the negative electrode from bottom to top; both the solid electrolyte layer 1 of the negative electrode and the solid electrolyte layer 3 of the positive electrode have a structure that is thin in the middle and thick on both sides, and the thicknesses on both sides are symmetrically distributed, gradually thickening from the center to both sides at the edges, and the thickness changes on both sides correspond to the thinned areas on both sides of the negative electrode sheet and the positive electrode sheet respectively.

[0071] Among them, the thickness of the central area of the negative electrode solid electrolyte layer 1 is H3 = 100um, the thickness of the thickened areas at both ends is H2 = 20um greater than that of the central area, and the length of the thickened areas on both sides is L1 = 20mm. The thickness of the central area of the positive electrode solid electrolyte layer 3 is H3 = 100um, the thickness of the thickened areas at both ends is H1 = 25um greater than that of the thickened areas on both sides, and the length of the thickened areas on both sides is L2 = 10mm. After the solid electrolyte layer is dried, it is peeled off from the first substrate 2 and the second substrate 4 to form the negative electrode solid electrolyte layer 1 and the positive electrode solid electrolyte layer 3. The corresponding substrate sides of the negative electrode solid electrolyte layer 1 and the positive electrode solid electrolyte layer 3 are laminated to form a double-layer solid electrolyte layer, such as Figure 3 .

[0072] Example 3

[0073] This embodiment provides a solid-state electrolyte battery based on unevenly coated solid electrolyte layers, which consists, from bottom to top, of a positive electrode sheet 5, a double-layer solid electrolyte layer, and a negative electrode sheet 6. The double-layer solid electrolyte layer consists, from bottom to top, of a positive electrode solid electrolyte layer 3 and a negative electrode solid electrolyte layer 1. Both the negative electrode solid electrolyte layer 1 and the positive electrode solid electrolyte layer 3 have a structure that is thin in the middle and thick at both sides. The thickness of the two sides is symmetrically distributed, and the edges gradually thicken from the center to the sides. The thickness changes on both sides correspond to the thinned areas on both sides of the negative electrode sheet and the positive electrode sheet, respectively.

[0074] Among them, the thickness of the central area of the negative electrode solid electrolyte layer 1 is H3 = 50um, the thickness of the thickened areas at both ends is H2 = 7um greater than that of the central area, and the length of the thickened areas on both sides is L1 = 10mm. The thickness of the central area of the positive electrode solid electrolyte layer 3 is H3 = 50um, the thickness of the thickened areas at both ends is H1 = 10um greater than that of the thickened areas on both sides, and the length of the thickened areas on both sides is L2 = 12mm. After the solid electrolyte layer is dried, it is peeled off from the first substrate 2 and the second substrate 4 to form the negative electrode solid electrolyte layer 1 and the positive electrode solid electrolyte layer 3. The corresponding substrate sides of the negative electrode solid electrolyte layer 1 and the positive electrode solid electrolyte layer 3 are laminated to form a double-layer solid electrolyte layer, such as Figure 3 .

[0075] Example 4

[0076] This embodiment provides a solid electrolyte battery based on an unevenly coated solid electrolyte layer, which has the unevenly coated solid electrolyte layer in the above-mentioned embodiment 1, and the negative solid electrolyte layer 1 and the positive solid electrolyte layer 3 of the double-layer solid electrolyte correspond to the negative electrode sheet 6 and the positive electrode sheet 5 respectively, forming a solid electrolyte and a pole piece, such as Figure 4 As shown;

[0077] Among them, the thickness H4 of the thinned area of the positive electrode tab is equal to the thickness H1 of the thickened area of the solid electrolyte layer 3 of the positive electrode, H4 = H1 = 10 μm. The length of the thinned area of the positive electrode tab is equal to the length of the thickened area of the solid electrolyte layer 3 of the positive electrode, that is, L2 = L4 = 12 mm. The thickness H5 of the thinned area of the negative electrode tab is equal to the thickness H2 of the thickened area of the solid electrolyte layer 1 of the negative electrode, H5 = H2 = 7 μm. The length L3 of the thinned area of the negative electrode tab is equal to the length L1 of the thickened area of the solid electrolyte layer 3 of the positive electrode, that is, L3 = L1 = 10 mm. The solid battery core is assembled in the order of positive electrode - double-layer solid electrolyte layer corresponding to the positive electrode side - double-layer solid electrolyte layer corresponding to the positive electrode side - negative electrode, as Figure 5 shown. The solid electrolyte can be perfectly attached to the edge areas on both sides of the positive and negative electrodes. After the battery core is cold-pressed or hot-pressed, the electrode tab and the electrolyte are in close contact, avoiding uneven current flow and uneven resistance caused by excessive edge gaps, improving the battery cycle performance, and reducing the internal resistance. Moreover, the thickness of the large surface is the same as that of the edge area, which is convenient for assembly.

[0078] Example 5

[0079] This example also provides a preparation method of a solid electrolyte battery based on an unevenly coated solid electrolyte layer, which includes the following steps:

[0080] Step S1: Prepare a solid electrolyte coating substrate;

[0081] The solid electrolyte coating substrate described in step S1 is a copper foil.

[0082] Step S2: Extrusion-coat the slurry of the polymer solid electrolyte onto the surface of the substrate in step S1 to form a solid electrolyte layer with different coating thicknesses. Specifically, the solid electrolyte layer has a structure that is thin in the middle and thick on both sides, and the thicknesses on both sides are symmetrically distributed, gradually increasing from the center to both sides along the edge. Then dry it to form a solid electrolyte layer with different coating thicknesses on the substrate. Among them, the thickness of the solid electrolyte layer of the positive electrode is less than the thickness of the solid electrolyte layer of the negative electrode;

[0083] Step S3: Separate the solid electrolyte layer of the positive electrode and the solid electrolyte layer of the negative electrode in step S2 from the substrate respectively, and attach the solid electrolyte layer of the positive electrode and the solid electrolyte layer of the negative electrode close to the substrate side to each other to form a double-layer solid electrolyte layer;

[0084] Step S4: Assemble in the order of the positive electrode tab, the solid electrolyte layer of the positive electrode of the double-layer solid electrolyte layer, the solid electrolyte layer of the negative electrode of the double-layer solid electrolyte layer, and the negative electrode tab;

[0085] The material of the positive electrode tab is nickel cobalt manganese ternary material;

[0086] The material of the negative electrode tab is graphite material;

[0087] Step S5: Perform hot pressing or cold pressing on the assembled electrode group to form a tightly adhered solid electrolyte battery.

[0088] The preferred embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0089] In addition, it should be noted that, in the case of no conflict, the various specific technical features described in the above specific embodiments can be combined in any suitable manner. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0090] Furthermore, any combination can be made between various different embodiments of the present invention, as long as it does not violate the idea of the present invention, and it should also be regarded as the content disclosed by the present invention.

Claims

1. A solid electrolyte battery based on an unevenly coated solid electrolyte layer, characterized in that, It is composed of a positive electrode plate (5), a double-layer solid electrolyte layer, and a negative electrode plate (6) from bottom to top. The double-layer solid electrolyte layer is composed of a solid electrolyte layer (3) of the positive electrode and a solid electrolyte layer (1) of the negative electrode from bottom to top. The solid electrolyte layer (3) of the positive electrode and the solid electrolyte layer (1) of the negative electrode both have a structure that is thin in the middle and thick on both sides, and the thicknesses on both sides are symmetrically distributed, with the edges gradually thickening from the center to both sides. The positive electrode plate (5) has a structure that is thick in the middle and thin on both sides, and is matched and adhered to the structure of the solid electrolyte layer (3) of the positive electrode. The negative electrode plate (6) has a structure that is thick in the middle and thin on both sides, and is matched and adhered to the structure of the solid electrolyte layer (1) of the negative electrode. The length L1 of the thickened areas on both sides of the solid electrolyte layer (3) of the positive electrode and the solid electrolyte layer (1) of the negative electrode is 5 - 20 mm. The thickness increase H1 of the thickened areas at both ends of the solid electrolyte layer (3) of the positive electrode compared to the central area is 5 - 25 μm, and the thickness increase H2 of the thickened areas at both ends of the solid electrolyte layer (1) of the negative electrode compared to the central area is 3 - 20 μm. The solid electrolyte is a polymer solid electrolyte.

2. The preparation method of a solid electrolyte battery based on an unevenly coated solid electrolyte layer as described in claim 1, characterized in that, It includes the following steps: Step S1: Prepare a solid electrolyte coating substrate. Step S2: Coat the slurry of the solid electrolyte onto the surface of the substrate in Step S1, and then dry it to form solid electrolyte layers with different coating thicknesses on the substrate. Among them, the thickness of the solid electrolyte layer of the positive electrode is less than the thickness of the solid electrolyte layer of the negative electrode. Step S3: Peel the solid electrolyte layer of the positive electrode and the solid electrolyte layer of the negative electrode in Step S2 from the substrate respectively, and attach the side close to the substrate of the solid electrolyte layer of the positive electrode and the solid electrolyte layer of the negative electrode to each other to form a double-layer solid electrolyte layer. Step S4: Assemble in the order of the positive electrode plate, the solid electrolyte layer of the positive electrode of the double-layer solid electrolyte layer, the solid electrolyte layer of the negative electrode of the double-layer solid electrolyte layer, and the negative electrode plate. Step S5: Perform hot pressing or cold pressing treatment on the assembled electrode group to form a tightly adhered solid electrolyte battery.

3. The preparation method of a solid electrolyte battery based on an unevenly coated solid electrolyte layer as claimed in claim 2, wherein, The solid electrolyte coating substrate described in Step S1 is copper foil, aluminum foil, nickel foil, polytetrafluoroethylene, or polyvinyl chloride.

4. The preparation method of a solid electrolyte battery based on an unevenly coated solid electrolyte layer according to claim 2, wherein Forming solid electrolyte layers with different coating thicknesses on the substrate in Step S2 specifically means that the solid electrolyte layer has a structure that is thin in the middle and thick on both sides, and the thicknesses on both sides are symmetrically distributed, with the edges gradually thickening from the center to both sides.

5. The preparation method of a solid electrolyte battery based on an unevenly coated solid electrolyte layer as claimed in claim 2, wherein, The coating method of the slurry of the solid electrolyte described in Step S2 is extrusion coating or gravure coating.

6. The preparation method of a solid electrolyte battery based on an unevenly coated solid electrolyte layer as claimed in claim 2, wherein, The materials of the positive electrode plate described in Step S4 include one or a mixture of several materials such as nickel cobalt manganese ternary materials, lithium iron phosphate materials, lithium manganese iron phosphate materials, lithium cobalt oxide materials, lithium nickel oxide materials, lithium manganese oxide materials, and lithium titanate materials.

7. The preparation method of a solid electrolyte battery based on an unevenly coated solid electrolyte layer as described in claim 2, characterized in that, The materials of the negative electrode plate described in Step S4 include one or a mixture of several materials such as graphite materials, lithium titanate materials, silicon-containing negative electrode materials, and lithium metal negative electrode materials.

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