Solid-state battery and method of manufacturing the same

Abstract

This invention discloses a solid-state battery and its fabrication method, relating to the field of lithium battery technology. The solid-state battery includes: a solid electrolyte layer, a positive electrode and a negative electrode disposed on opposite sides of the solid electrolyte layer, wherein the solid electrolyte layer includes: a conductive layer and a first doped layer doped with a lithiophilic dopant material disposed on one side of the conductive layer; the first doped layer is located between the negative electrode and the conductive layer, and is in contact with the negative electrode. The solid electrolyte layer of this solid-state battery forms an asymmetric functional gradient, and its side near the negative electrode can promote uniform lithium nucleation, effectively reducing interfacial resistance.

Description

Technical Field

[0001] This invention relates to the field of lithium battery technology, and in particular to a solid-state battery and its preparation method. Background Technology

[0002] For solid-state batteries, the interface performance between the solid electrolyte and the negative electrode is a key factor affecting the battery's performance. On the one hand, poor physical contact between the rigid solid electrolyte layer and the flexible lithium negative electrode can easily lead to high interfacial impedance. On the other hand, uneven lithium deposition can easily occur at the contact between the rigid solid electrolyte layer and the flexible lithium negative electrode, resulting in the formation and growth of lithium dendrites, which can penetrate the electrolyte and cause internal short circuits. Summary of the Invention

[0003] In view of this, embodiments of the present invention provide a solid-state battery and a method for preparing the same. The solid electrolyte layer of the solid-state battery forms an asymmetric functional gradient, and the side near the negative electrode can promote uniform lithium nucleation and effectively reduce the interface resistance.

[0004] To achieve the above objectives, in a first aspect, according to an embodiment of the present invention, a solid-state battery is provided, comprising: a solid electrolyte layer, a positive electrode and a negative electrode disposed on both sides of the solid electrolyte layer, wherein, The solid electrolyte layer includes: a conductive layer and a first doped layer doped with a lithiophilic dopant material disposed on one side of the conductive layer; The first doped layer is located between the negative electrode and the conductive layer, and is in contact with the negative electrode.

[0005] Optionally, the solid electrolyte layer further includes: A second doped layer, containing an insulating metal oxide, is disposed between the positive electrode and the conductive layer, and the second doped layer is in contact with the positive electrode.

[0006] Optionally, the thickness of the first doped layer is 1 μm to 5 μm.

[0007] Optionally, the lithiophilic doped material includes silver oxide, zinc oxide, or silicon oxide.

[0008] Optionally, the first doped layer contains 2wt% to 12wt% of the mass fraction of the lithophilic doped material.

[0009] Optionally, the thickness of the second doped layer is 1 μm to 5 μm.

[0010] Optionally, the insulating metal oxide doped in the second doped layer is aluminum oxide and / or tantalum pentoxide.

[0011] Optionally, the second doped layer contains an insulating metal oxide with a mass fraction of 1 wt% to 6 wt%.

[0012] Optionally, the first doped layer, the conductive layer, and the second doped layer are integrally formed.

[0013] Optionally, the first doped layer and the second doped layer further include a solid electrolyte, wherein the solid electrolyte included in the first doped layer and the second doped layer is the same as the solid electrolyte included in the conductive layer.

[0014] Optionally, the conductive layer comprises a garnet-type solid electrolyte.

[0015] Optionally, the thickness of the conductive layer is 30μm to 50μm.

[0016] Secondly, embodiments of the present invention provide a method for preparing a solid-state battery, comprising: Step 1: Mix the lithiophilic doped material with the solid electrolyte to form a first mixture; Step 2: Lay out the first mixture and the solid electrolyte in layers and sinter at high temperature to form a solid electrolyte layer. The solid electrolyte forms the conductive layer in the solid electrolyte layer, and the first mixture forms the first doped layer in the solid electrolyte layer. Step 3: Assemble the positive electrode, negative electrode and solid electrolyte layer, wherein the positive electrode and the negative electrode are respectively disposed on both sides of the solid electrolyte layer, and the first doped layer is located between the negative electrode and the conductive layer and is in contact with the negative electrode.

[0017] Optionally, step 1 further includes: mixing the insulating metal oxide with the solid electrolyte to form a second mixture; Step 2 further includes: before high-temperature sintering, layering the second mixture onto the side of the solid electrolyte away from the first mixture.

[0018] Optionally, if the first mixture, the solid electrolyte, and the second mixture are all slurries, step 2 includes: sequentially coating the first mixture, the solid electrolyte, and the second mixture to form a multi-layer green strip with a structure of first mixture-solid electrolyte-second mixture; cutting the green strip; and sintering the cut green strip at high temperature.

[0019] Optionally, if the first mixture, the solid electrolyte, and the second mixture are all powders, step 2 includes: sequentially filling the first mixture, the solid electrolyte, and the second mixture into a mold, cold pressing them at a pressure of 150MPa to 350MPa to form a multilayer structure of the first mixture-solid electrolyte-second mixture, and sintering at high temperature.

[0020] Optionally, step 2 includes: high-temperature sintering at an oxygen atmosphere at a temperature of 1050℃~1200℃ for 10h~14h.

[0021] One embodiment of the above invention has the following advantages or beneficial effects: The solid-state battery provided by the embodiment of the present invention, by designing the solid electrolyte layer to include a conductive layer and a first doped layer doped with a lithiophilic dopant material disposed on one side of the conductive layer, wherein the lithiophilic dopant material doped in the first doped layer has lithiophilic properties to improve the uniformity of lithium deposition, can promote uniform lithium nucleation, and the conductive layer and the first doped layer work together to effectively reduce the interface resistance.

[0022] The further effects of the aforementioned unconventional alternative methods will be explained below in conjunction with specific implementation methods. Attached Figure Description

[0023] The accompanying drawings are provided to better understand the invention and are not intended to unduly limit the scope of the invention. Wherein: Figure 1 This is a cross-sectional structural diagram of a first structure of a solid-state battery according to an embodiment of the present invention. Figure 2 This is a cross-sectional structural diagram of a second structure of a solid-state battery according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the main process of a solid-state battery preparation method according to an embodiment of the present invention.

[0024] Explanation of reference numerals in the attached figures: 10-Solid electrolyte layer; 11-Conductive layer; 12-First doped layer; 13-Second doped layer; 20-Positive electrode; 30-Negative electrode. Detailed Implementation

[0025] Solid-state batteries, especially solid-state lithium metal batteries (SSLMBs), have emerged as a promising next-generation energy storage technology due to their potential for high energy density and enhanced safety. However, practical applications of solid-state batteries are hampered by poor physical contact between the negative electrode (particularly the lithium metal negative electrode) and the solid electrolyte (SSE), which can easily lead to high interfacial impedance, particularly for garnet-type Li7La3Zr2O. 12Ceramic electrolytes such as LLZO, which are inherently "lithium-repellent," are more prone to poor physical contact between the negative electrode and the solid electrolyte. Furthermore, poor physical contact between the negative electrode and the solid electrolyte easily leads to uneven lithium deposition. This uneven lithium deposition results in the formation and growth of lithium dendrites, which may penetrate the solid electrolyte, causing internal short circuits. Simultaneously, the formation and growth of lithium dendrites can easily lead to mechanical failure due to lithium volume changes during battery cycling. Therefore, an improved solid electrolyte structure is needed to address the aforementioned technical problems of solid-state batteries.

[0026] The following description, in conjunction with the accompanying drawings, illustrates exemplary embodiments of the present invention, including various details to aid understanding. These details should be considered merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the invention. Similarly, for clarity and brevity, descriptions of well-known functions and structures are omitted in the following description.

[0027] It should be noted that, unless otherwise specified, the embodiments of the present invention and the technical features thereof can be combined with each other.

[0028] Specifically, embodiments of the present invention provide two basic solid-state battery structures. Figure 1 and Figure 2 The following are schematic cross-sectional views of two basic solid-state battery structures provided in the embodiments of the present invention.

[0029] like Figure 1 As shown, the first basic structure of the solid-state battery may include: a solid electrolyte layer 10, a positive electrode 20 and a negative electrode 30 disposed on both sides of the solid electrolyte layer 10, wherein the solid electrolyte layer 10 includes: a conductive layer 11 and a first doped layer 12 doped with a lithium-loving dopant material disposed on one side of the conductive layer 11; the first doped layer 12 is located between the negative electrode 30 and the conductive layer 11 and is in contact with the negative electrode 30.

[0030] like Figure 2 As shown, the second basic structure of this solid-state battery also includes: a solid electrolyte layer 10, a positive electrode 20 and a negative electrode 30 respectively disposed on both sides of the solid electrolyte layer 10, wherein, with Figure 1 The solid-state battery structure shown is different from the first basic structure. The second basic structure of the solid-state battery includes a solid electrolyte layer 10, which, in addition to a conductive layer 11 and a first doped layer 12 with a lithium-loving dopant material disposed on the side of the conductive layer 11 near the negative electrode 30, also includes a second doped layer 13 with an insulating metal oxide disposed between the positive electrode 20 and the conductive layer 11, and the second doped layer 13 is in contact with the positive electrode 20.

[0031] The two basic solid-state battery structures described above are designed with a solid electrolyte layer including a conductive layer and a first doped layer doped with a lithiophilic dopant material disposed on one side of the conductive layer. The lithiophilic dopant material in the first doped layer has lithiophilic properties to improve the uniformity of lithium deposition and promote uniform lithium nucleation. Furthermore, the conductive layer and the first doped layer work together to effectively reduce the interface resistance.

[0032] In addition, the solid electrolyte layer of the two basic solid-state battery structures mentioned above generally contains a conductive layer that is basically undoped and of high purity, which can maximize the ionic conductivity and mechanical strength of the solid electrolyte layer 10.

[0033] Furthermore, for the second type of solid-state battery, a second doped layer 13, doped with an insulating metal oxide, is provided between the positive electrode 20 and the conductive layer 11, which enhances the electrochemical stability of the high-voltage positive electrode active material.

[0034] For the two basic solid-state battery structures mentioned above, the conductive layer 11 and the first doped layer 12 are integrally formed. More specifically, the conductive layer 11 and the first doped layer 12 are integrally formed, such as through die extrusion sintering, multilayer casting casting sintering, etc. The integral structure of the conductive layer 11 and the first doped layer 12 can eliminate the physical interface, ensuring excellent mechanical integrity and a stable, low-resistance ion transport path throughout the electrolyte, and can significantly improve the reliability and safety of the battery during long-term cycling.

[0035] Furthermore, the integrated conductive layer 11 and the first doped layer 12 achieve a gradient structure for a seamless transition from the functional region to the bulk region in the solid electrolyte layer. This avoids ion transport bottlenecks that may occur at independent interfaces, thereby achieving a lower and more stable areal resistivity (ASR) and improving the rate performance and power density of the solid-state battery.

[0036] Furthermore, the conductive layer 11 and the first doped layer 12 are integrally structured, wherein the conductive layer 11 provides a robust physical barrier and the first doped layer 12 provides a lithium-friendly interface that promotes uniform lithium nucleation. The gradient structure realizes the vehicle-mounted defense mechanism, which can more effectively suppress the nucleation and growth of lithium dendrites, thereby improving the critical current density (CCD) and safety of the battery.

[0037] Furthermore, for the second type of solid-state battery structure, the first doped layer 12, the conductive layer 11, and the second doped layer 13 are integrally formed. More specifically, the first doped layer 12, the conductive layer 11, and the second doped layer 13 are integrally formed, such as through die extrusion sintering or multilayer casting sintering. In addition to the aforementioned beneficial effects of the integrally formed conductive layer 11 and the first doped layer 12, the second doped layer 13 and the conductive layer 11 can also form a gradient structure integrally formed, which eliminates the interface between the second doped layer 13 and the conductive layer 11, further improving the overall mechanical robustness and enhancing the reliability and safety of the solid-state battery during long-term cycling. Furthermore, the gradient structure integrally formed by the second doped layer 13 and the conductive layer 11 can further enhance the electrochemical stability of the high-voltage cathode active material.

[0038] In addition, the integrated structure of the first doped layer 12 and the conductive layer 11 means that there is no clear boundary between the first doped layer 12 and the conductive layer 11, thus preventing lithium from accumulating between the first doped layer 12 and the conductive layer 11.

[0039] In this embodiment of the invention, for either of the two basic solid-state battery structures described above, the thickness of the first doped layer 12 can be 1 μm to 5 μm. For example, the thickness of the first doped layer 12 can be 1 μm, 2 μm, 3 μm, 4 μm, or 5 μm, etc. This facilitates the deposition of lithium ions in the first doped layer 12 and ensures uniform deposition of lithium ions in the first doped layer 12.

[0040] In this embodiment of the invention, for either of the two basic solid-state battery structures described above, the first doped layer 12 of the solid-state battery includes a lithiophilic dopant material comprising silver oxide, zinc oxide, or silicon oxide. Selecting these lithiophilic dopant materials can further improve the uniformity of lithium-ion deposition in the first doped layer 12. More specifically, the first doped layer 12 contains a lithiophilic dopant material with a mass fraction of 2 wt% to 12 wt%. For example, the mass fraction of the lithiophilic dopant material in the first doped layer 12 can be 2 wt%, 5 wt%, 7 wt%, 10 wt%, or 12 wt%, etc.

[0041] Furthermore, for the solid-state battery with the second basic structure described above, the thickness of the second doped layer 13 is 1 μm to 5 μm. For example, the thickness of the second doped layer 13 can be 1 μm, 2 μm, 3 μm, 4 μm, or 5 μm, which helps to provide long-term cycle stability of the solid-state battery.

[0042] Furthermore, for the solid-state battery with the second basic structure mentioned above, the insulating metal oxide doped in the second doped layer 13 is aluminum oxide and / or tantalum pentoxide, which can stabilize the structural stability of the solid electrolyte (such as garnet-type solid electrolyte, LLZO) and suppress the interaction between the solid electrolyte and high-voltage cathode materials (such as LiNi). x Mn γ The second doped layer 13 reduces harmful side reactions of Co2O2, thereby improving the mechanical robustness of the solid-state battery and further enhancing the electrochemical stability of the high-voltage cathode active material. Preferably, the second doped layer 13 contains an insulating metal oxide with a mass fraction of 1 wt% to 6 wt%. For example, the mass fraction of the insulating metal oxide in the second doped layer 13 can be 1 wt%, 2 wt%, 4 wt%, 5 wt%, or 6 wt%.

[0043] In this embodiment of the invention, the first doped layer 12 and the second doped layer 13 further include a solid electrolyte. The solid electrolyte included in the first doped layer 12 and the second doped layer 13 is the same as the solid electrolyte included in the conductive layer 11, so as to further eliminate the interface between the first doped layer 12 and the conductive layer 11 and the interface between the second doped layer 13 and the conductive layer 11, ensuring the excellent mechanical integrity of the solid electrolyte layer 10 and a stable and low-resistance ion transport path throughout the solid electrolyte layer 10.

[0044] The conductive layer 11 typically includes a garnet-type solid electrolyte.

[0045] In the embodiments of the present invention, the solid-state battery provided in any of the above embodiments generally includes a conductive layer 11 with a thickness of 30μm to 50μm. For example, the thickness of the conductive layer 11 can be 30μm, 40μm, or 50μm. By controlling the thickness of the conductive layer 11, a robust mechanical barrier can be provided to resist lithium dendrite penetration, and high ionic conductivity can promote rapid lithium-ion transport.

[0046] Furthermore, embodiments of the present invention provide a method for preparing a solid-state battery. Specifically, as shown in the figure... Figure 3 As shown, the method for fabricating this solid-state battery may include the following steps: Step S301: Mix the lithiophilic doped material with the solid electrolyte to form a first mixture.

[0047] Step S302: Lay out the first mixture and the solid electrolyte, and sinter at high temperature to form a solid electrolyte layer 10. The solid electrolyte forms a conductive layer 11 in the solid electrolyte layer 10, and the first mixture forms a first doped layer 12 in the solid electrolyte layer 10.

[0048] Step S303: Assemble the positive electrode 20, the negative electrode 30 and the solid electrolyte layer 10, wherein the positive electrode 20 and the negative electrode 30 are respectively disposed on both sides of the solid electrolyte layer 10, and the first doped layer 12 is located between the negative electrode 30 and the conductive layer 11 and is in contact with the negative electrode 30.

[0049] The above preparation method simplifies the assembly process of solid-state batteries and has greater potential for large-scale production.

[0050] In addition, the solid-state battery prepared by the above preparation method is designed with a solid electrolyte layer including a conductive layer and a first doped layer doped with a lithiophilic dopant material disposed on one side of the conductive layer. The lithiophilic dopant material doped in the first doped layer has lithiophilic properties to improve the uniformity of lithium deposition and promote uniform lithium nucleation. Furthermore, the conductive layer and the first doped layer work together to effectively reduce the interface resistance.

[0051] The above preparation method yields Figure 1 The structure of the solid-state battery is shown.

[0052] In addition, based on the above preparation method, step S301 may further include: mixing the insulating metal oxide with the solid electrolyte to form a second mixture. Step S302 further includes: before high-temperature sintering, layering the second mixture on the side of the solid electrolyte away from the first mixture, and then performing step S303 to obtain... Figure 2 The structure of the solid-state battery is shown.

[0053] Since the first mixture, the solid electrolyte, and the second mixture have different forms, step S302 adopts different implementation schemes.

[0054] Specifically, when the first mixture, the solid electrolyte, and the second mixture are all slurries, step S302 may include: sequentially coating the first mixture, the solid electrolyte, and the second mixture to form a multi-layer green strip with a structure of first mixture-solid electrolyte-second mixture; cutting the green strip; and sintering the cut green strip at high temperature to obtain a solid electrolyte layer.

[0055] When the first mixture, solid electrolyte, and second mixture are all powders, step S302 may include: sequentially filling the first mixture, solid electrolyte, and second mixture into a mold, cold-pressing them under a pressure of 150MPa to 350MPa to form a multilayer structure of the first mixture-solid electrolyte-second mixture, and then sintering at high temperature. For example, the cold-pressing pressure may be 150MPa, 280MPa, 300MPa, 320MPa, or 350MPa, etc.

[0056] Step S302 may include: high-temperature sintering in an oxygen atmosphere at a temperature of 1050℃~1200℃ for 10h~14h. For example, if the first mixture, solid electrolyte, and second mixture are all slurries, the cut green strip is sintered at an oxygen atmosphere at a temperature of 1050℃~1200℃ for 10h~14h. If the first mixture, solid electrolyte, and second mixture are all slurries, the first mixture-solid electrolyte-second mixture is sintered at an oxygen atmosphere at a temperature of 1050℃~1200℃ and then cold-pressed to form a multilayer structure of the first mixture-solid electrolyte-second mixture for 10h~14h. For example, the high-temperature sintering temperature may be 1050℃, 1100℃, 1150℃, or 1200℃, and the high-temperature sintering time may be 10h, 12h, 13h, or 14h. High-temperature sintering forms a dense and continuous structure in the solid electrolyte layer, and the functional gradient is permanently integrated into the solid electrolyte layer, eliminating the interface between the conductive layer and the first doped layer, as well as the interface between the conductive layer and the second doped layer.

[0057] The following examples illustrate in detail the fabrication method of the solid-state battery described above.

[0058] Example 1

[0059] Step A: Three different LLZO precursor slurries were prepared. The first slurry, applied near the negative electrode, consisted of LLZO precursor powder and 5 wt% nano-zinc oxide (ZnO) powder. The second slurry consisted of pure LLZO precursor powder. The third slurry, applied near the positive electrode, consisted of LLZO precursor powder and 2 wt% nano-alumina (Al2O3) powder. Using a multilayer casting machine, the first slurry (target thickness 5 μm), the second slurry (target thickness 40 μm), and the third slurry (target thickness 5 μm) on the negative electrode side were sequentially coated into multilayer green belts.

[0060] Step B: The green strip is punched into a circular sheet and co-sintered in an oxygen atmosphere at 1100°C for 12 hours to form a dense, monolithic asymmetric solid electrolyte layer.

[0061] Step C: After assembling the asymmetric solid electrolyte layer with the lithium metal negative electrode, due to the lithiophilicity of the ZnO doped region, the interfacial resistance between the asymmetric solid electrolyte layer and the lithium metal negative electrode is reduced from 1500 Ω·cm² to below 100 Ω·cm².

[0062] Step D: Assemble the structure assembled in step C with the NCM811 positive electrode to form a full cell. After 300 cycles at a 0.5C rate, the capacity retention rate of the full cell can still reach more than 90%.

[0063] Example 2

[0064] The difference from Example 1 is that the 5 wt% nano-zinc oxide (ZnO) powder in the bulk phase of the first slurry applied near the negative electrode is replaced with 3 wt% nano-silver oxide (Ag2O), and the 2 wt% nano-alumina (Al2O3) powder in the bulk phase of the third slurry applied near the positive electrode is replaced with 1 wt% tantalum pentoxide (Ta2O5). Silver is chosen due to its excellent lithiophilicity, which allows it to form alloys with lithium, significantly reducing the lithium nucleation overpotential. Tantalum effectively stabilizes the cubic phase of LLZO and suppresses side reactions with the high-nickel cathode.

[0065] Furthermore, the difference from Example 1 is that Example 2 uses a powder co-pressing method to prepare the asymmetric solid electrolyte layer. Specifically, a first powder containing 3 wt% nano-silver oxide (Ag2O) and LLZO precursor powder, a second powder composed of LLZO precursor powder, and a third powder containing 2 wt% nano-alumina (Al2O3) powder and LLZO precursor powder are sequentially filled into a mold, cold-pressed under a pressure of 200 MPa, and then pressureless sintered at 1150°C in an oxygen atmosphere.

[0066] In the test, the critical current density (CCD) of the monolithic solid electrolyte layer fabricated in Example 2 increased to 4.0 mA·cm⁻¹. - ² indicates that the solid electrolyte layer prepared in Example 2 has a significantly enhanced ability to suppress dendrite growth.

[0067] Example 3

[0068] The difference from Example 1 is that the 5 wt% nano zinc oxide (ZnO) powder applied to the bulk phase of the first slurry near the negative electrode side is replaced with 10 wt% nano silicon dioxide (SiO2).

[0069] A gradient green embryo was prepared by sequentially layering slurries containing LLZO precursor powder and 10 wt% nano-silica (SiO2), a second slurry from Example 1, and a third slurry from Example 1 using a sequential centrifugal casting method. The green embryo was then co-sintered at 1100°C in an oxygen atmosphere for 15 hours, resulting in a solid electrolyte layer. In this layer, the SiO2 on the negative electrode side was partially reduced and reacted with lithium to form a lithium-affinity Li. x The Si alloy phase improves interfacial wettability. This solid electrolyte layer was applied in a scenario requiring high power output. Electrochemical tests showed that due to the significant reduction in interfacial impedance, the battery's rate performance was significantly improved, still releasing more than 80% of its capacity at a high rate of 5C.

[0070] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can occur depending on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A solid-state battery, characterized in that, include: A solid electrolyte layer (10), a positive electrode (20) and a negative electrode (30) disposed on both sides of the solid electrolyte layer (10), wherein, The solid electrolyte layer (10) includes: a conductive layer (11) and a first doped layer (12) doped with a lithiophilic dopant material disposed on one side of the conductive layer (11). The first doped layer (12) is located between the negative electrode (30) and the conductive layer (11) and is in contact with the negative electrode (30).

2. The solid-state battery according to claim 1, characterized in that, The solid electrolyte layer (10) further includes: A second doped layer (13) of an insulating metal oxide is disposed between the positive electrode (20) and the conductive layer (11), and the second doped layer (13) is in contact with the positive electrode (20).

3. The solid-state battery according to claim 1 or 2, characterized in that, The thickness of the first doped layer (12) is 1 μm to 5 μm; And / or, The lithiophilic doping material includes: silver oxide, zinc oxide, or silicon oxide; And / or, The first doped layer (12) contains 2wt% to 12wt% of the lithophile doped material.

4. The solid-state battery according to claim 2, characterized in that, The thickness of the second doped layer (13) is 1 μm to 5 μm; And / or, The insulating metal oxide doped in the second doped layer (13) is aluminum oxide and / or tantalum pentoxide; And / or, The second doped layer (13) contains an insulating metal oxide with a mass fraction of 1wt% to 6wt%.

5. The solid-state battery according to claim 2 or 4, characterized in that, The first doped layer (12), the conductive layer (11) and the second doped layer (13) are integrally formed structures; And / or, The first doped layer (12) and the second doped layer (13) further include a solid electrolyte, and the solid electrolyte included in the first doped layer (12) and the second doped layer (13) is the same as the solid electrolyte included in the conductive layer (11); And / or, The conductive layer (11) includes a garnet-type solid electrolyte; And / or, The thickness of the conductive layer (11) is 30μm~50μm.

6. A method for preparing a solid-state battery, characterized in that, include: Step 1: Mix the lithiophilic doped material with the solid electrolyte to form a first mixture; Step 2: Lay out the first mixture and the solid electrolyte in layers and sinter at high temperature to form a solid electrolyte layer (10). The solid electrolyte forms a conductive layer (11) in the solid electrolyte layer (10), and the first mixture forms a first doped layer (12) in the solid electrolyte layer (10). Step 3: Assemble the positive electrode (20), negative electrode (30) and solid electrolyte layer (10), wherein the positive electrode (20) and the negative electrode (30) are respectively disposed on both sides of the solid electrolyte layer (10), and the first doped layer (12) is located between the negative electrode (30) and the conductive layer (11) and is in contact with the negative electrode (30).

7. The preparation method according to claim 6, characterized in that, Step 1 further includes: mixing the insulating metal oxide with the solid electrolyte to form a second mixture; Step 2 further includes: before high-temperature sintering, layering the second mixture onto the side of the solid electrolyte away from the first mixture.

8. The preparation method according to claim 7, characterized in that, When the first mixture, the solid electrolyte, and the second mixture are all slurries, Step 2 includes: sequentially coating the first mixture, the solid electrolyte, and the second mixture to form a multilayer green strip with a structure of first mixture-solid electrolyte-second mixture; cutting the green strip; and sintering the cut green strip at high temperature.

9. The preparation method according to claim 7, characterized in that, When the first mixture, the solid electrolyte, and the second mixture are all powders, Step 2 includes: sequentially filling the first mixture, the solid electrolyte, and the second mixture into a mold, cold pressing them at a pressure of 150MPa~350MPa to form a multilayer structure of the first mixture-solid electrolyte-second mixture, and then sintering them at high temperature.

10. The preparation method according to any one of claims 6 to 9, characterized in that, Step 2 includes: high-temperature sintering at 1050℃~1200℃ in an oxygen atmosphere for 10h~14h.

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