Method for producing a lithium dendrite resistant solid state battery

Abstract

The application discloses a preparation method of a solid-state battery capable of resisting lithium dendrites, which comprises the following steps: preparing a buffer layer slurry, interface coating, pre-drying and in-situ solidification. Through precise proportioning of a four-component group and integrated in-situ solidification design, an interface buffer layer is accurately positioned between a lithium metal negative electrode and an electrolyte and is formed, which can form a uniform lithium ion transmission channel, guide lithium ions to vertically and uniformly reach the surface of the lithium metal negative electrode, buffer the volume change of the lithium negative electrode, in-situ form a stable SEI film on the passivation phase of the interface, eliminate the growth hot spot of lithium dendrites, and inhibit the growth of lithium dendrites from the source. Meanwhile, through battery-level integrated in-situ crosslinking solidification, the buffer layer is integrally and closely combined with the lithium negative electrode and the electrolyte, the interface impedance is significantly reduced, and the interface compatibility and long-term stability of the electrolyte and the lithium negative electrode are improved.

Description

Technical Field

[0001] This invention relates to the field of solid-state battery technology, and in particular to a method for preparing a solid-state battery resistant to lithium dendrite formation. Background Technology

[0002] Solid-state batteries, as a core direction of next-generation energy storage technology, have attracted widespread attention due to their advantages of high energy density and high safety. Lithium metal anodes, with a theoretical specific capacity as high as 3860 mAh / g, far exceeding that of traditional graphite anodes (372 mAh / g), are key electrode materials for improving the energy density of solid-state batteries.

[0003] Lithium ions preferentially undergo reduction deposition at defect sites on the surface of lithium metal anodes, gradually forming needle-like and dendritic lithium metal crystals. These lithium dendrites continue to grow, consuming electrolyte and disrupting the electrolyte-anode interface, leading to battery capacity decay and increased interfacial impedance. Furthermore, when the dendrite growth length exceeds the electrolyte thickness, it can pierce the electrolyte layer, causing a direct short circuit between the positive and negative electrodes, generating significant Joule heating, inducing thermal runaway, and seriously threatening battery safety. To address these issues, existing technologies have proposed various solutions, such as applying ultra-high pressure to suppress dendrite growth, modifying the surface of the lithium metal anode, and electrolyte doping modification. However, these solutions all have significant limitations: applying ultra-high pressure (10-20 MPa) is unsuitable for practical applications such as automotive and accelerates battery aging; existing lithium metal anode surface modification technologies, such as the polymer composite modification layer disclosed in CN202310419037.7, mostly use binary or ternary component systems, relying on a single physical barrier or chemical passivation mechanism, failing to achieve synergistic control of ion transport uniformity and interface stability. The modification layer is prone to cracking during charge-discharge cycles due to electrode volume expansion, and cannot effectively block dendrites in the long term; electrolyte doping modification can only slightly improve anti-dendrite ability, and cannot fundamentally solve the core problem of uneven lithium-ion deposition; in addition, the room temperature in-situ solid electrolyte technology disclosed in CN120109286A, although adopting the in-situ solidification approach, focuses on the preparation of the electrolyte bulk and does not involve the precise control of the lithium anode interface, failing to solve the pain point of uneven lithium-ion deposition at the interface. Therefore, it is necessary to propose a new solution to address the above problems. Summary of the Invention

[0004] In view of this, the present invention addresses the deficiencies of the prior art, and its main objective is to provide a method for preparing a solid-state battery that is resistant to lithium dendrite formation. This method can effectively solve the problems of existing lithium metal anodes easily forming lithium crystals, consuming electrolytes, and damaging the interfacial contact between the electrolyte and the anode, leading to battery capacity decay and increased interfacial impedance.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing a solid-state battery resistant to lithium dendrite formation includes the following steps: (1) Preparation of buffer layer slurry Li3PO4 particles were added to an organic solvent and ultrasonically dispersed at 180 W for 25 min to obtain a uniform Li3PO4 dispersion. Subsequently, PEGDA, LiTFSI and FEC were added to the Li3PO4 dispersion. The mass ratio of Li3PO4 particles, PEGDA, LiTFSI and FEC was (60-75):(18-30):(5-8):2. The mixture was stirred at 600 r / min for 1.5 h in an inert gas atmosphere to obtain a buffer layer slurry. (2) Interface coating The buffer layer slurry obtained in step (1) is uniformly coated onto the surface of the lithium metal anode by means of coating, so as to obtain the coated lithium metal anode. (3) Pre-drying The coated lithium metal anode obtained in step (2) was placed in a vacuum oven at 35°C and dried for 1.5 h to remove the organic solvent, thus obtaining the dried anode sheet. (4) In-situ curing The dried negative electrode obtained in step (3) is stacked sequentially with LLZO electrolyte and LiCoO2 positive electrode to form an unencapsulated button cell. The unencapsulated button cell is placed in an 85°C oven and heated for 1.5 hours to trigger PEGDA crosslinking and curing, forming a dense buffer layer that can resist lithium dendrite interfaces, thus obtaining a solid-state battery that can resist lithium dendrites.

[0006] As a preferred embodiment, in step (1), the viscosity of the buffer layer slurry is 120 cps.

[0007] As a preferred option, in step (1), the inert gas is argon.

[0008] As a preferred embodiment, in step (1), the organic solvent is acetonitrile.

[0009] As a preferred embodiment, in step (1), the particle size of the Li3PO4 particles is 100 nm.

[0010] As a preferred option, in step (2), the buffer layer slurry obtained in step (1) is uniformly coated on the surface of the lithium metal anode by a doctor blade coating method to obtain the coated lithium metal anode; As a preferred embodiment, in step (2), the coating thickness is 3-15 μm.

[0011] Compared with the prior art, the present invention has obvious advantages and beneficial effects. Specifically, as can be seen from the above technical solution: By employing a precise ratio of quaternary components and an integrated in-situ curing design, an interface buffer layer is precisely positioned between the lithium metal anode and the electrolyte, forming a uniform lithium-ion transport channel that guides lithium ions to the surface of the lithium metal anode vertically and uniformly, buffering the volume change of the lithium anode. The passivation phase at the interface forms a stable SEI film in situ, eliminating lithium dendrite growth hotspots and inhibiting lithium dendrite growth from the source. At the same time, through battery-level integrated in-situ crosslinking curing, the buffer layer is tightly integrated with the lithium anode and electrolyte, significantly reducing interface impedance and improving the interfacial compatibility and long-term stability of the electrolyte and lithium anode.

[0012] To more clearly illustrate the structural features and effects of the present invention, the present invention will be described in detail below with reference to specific embodiments. Detailed Implementation

[0013] This invention discloses a method for preparing a solid-state battery resistant to lithium dendrite formation, which includes the following steps: (1) Preparation of buffer layer slurry Li3PO4 particles were added to an organic solvent and ultrasonically dispersed at 180 W for 25 min to obtain a uniform Li3PO4 dispersion. Subsequently, PEGDA, LiTFSI, and FEC were added to the Li3PO4 dispersion, with a mass ratio of Li3PO4 particles, PEGDA, LiTFSI, and FEC of (60-75):(18-30):(5-8):2. The mixture was stirred at 600 r / min for 1.5 h in an inert gas atmosphere to obtain a buffer layer slurry. The viscosity of the buffer layer slurry was 120 cps, the inert gas was argon, the organic solvent was acetonitrile, and the particle size of the Li3PO4 particles was 100 nm.

[0014] (2) Interface coating The buffer layer slurry obtained in step (1) is uniformly coated onto the surface of the lithium metal anode using a doctor blade coating method to obtain the coated lithium metal anode; the coating thickness is 3-15 μm.

[0015] (3) Pre-drying The coated lithium metal anode obtained in step (2) was placed in a vacuum oven at 35°C and dried for 1.5 h to remove the organic solvent, thus obtaining the dried anode sheet. (4) In-situ curing The dried negative electrode obtained in step (3) is stacked sequentially with LLZO electrolyte and LiCoO2 positive electrode to form an unencapsulated button cell. The unencapsulated button cell is placed in an 85°C oven and heated for 1.5 hours to trigger PEGDA crosslinking and curing, forming a dense buffer layer that can resist lithium dendrite interfaces, thus obtaining a solid-state battery that can resist lithium dendrites.

[0016] The following detailed description is based on several embodiments.

[0017] Example 1 (1) Preparation of buffer layer slurry Li3PO4 particles were added to an organic solvent and ultrasonically dispersed at 180 W for 25 min to obtain a uniform Li3PO4 dispersion. Subsequently, PEGDA, LiTFSI, and FEC were added to the Li3PO4 dispersion in a mass ratio of 75:18:5:2. The mixture was stirred at 600 r / min for 1.5 h in an inert gas atmosphere to obtain a buffer layer slurry. The viscosity of the buffer layer slurry was 120 cps, the inert gas was argon, the organic solvent was acetonitrile, and the particle size of the Li3PO4 particles was 100 nm.

[0018] (2) Interface coating The buffer layer slurry obtained in step (1) is uniformly coated onto the surface of the lithium metal anode using a doctor blade coating method to obtain the coated lithium metal anode; the coating thickness is 8 μm.

[0019] (3) Pre-drying The coated lithium metal anode obtained in step (2) was placed in a vacuum oven at 35°C and dried for 1.5 h to remove the organic solvent, thus obtaining the dried anode sheet. (4) In-situ curing The dried negative electrode obtained in step (3) is stacked sequentially with LLZO electrolyte and LiCoO2 positive electrode to form an unencapsulated button cell. The unencapsulated button cell is placed in an 85°C oven and heated for 1.5 hours to trigger PEGDA crosslinking and curing, forming a dense buffer layer that can resist lithium dendrite interfaces, thus obtaining a solid-state battery that can resist lithium dendrites.

[0020] Example 2 (1) Preparation of buffer layer slurry Li3PO4 particles were added to an organic solvent and ultrasonically dispersed at 180 W for 25 min to obtain a uniform Li3PO4 dispersion. Subsequently, PEGDA, LiTFSI, and FEC were added to the Li3PO4 dispersion in a mass ratio of 75:18:5:2. The mixture was stirred at 600 r / min for 1.5 h in an inert gas atmosphere to obtain a buffer layer slurry. The viscosity of the buffer layer slurry was 120 cps, the inert gas was argon, the organic solvent was acetonitrile, and the particle size of the Li3PO4 particles was 100 nm.

[0021] (2) Interface coating The buffer layer slurry obtained in step (1) is uniformly coated onto the surface of the lithium metal anode using a doctor blade coating method to obtain the coated lithium metal anode; the coating thickness is 3 μm.

[0022] (3) Pre-drying The coated lithium metal anode obtained in step (2) was placed in a vacuum oven at 35°C and dried for 1.5 h to remove the organic solvent, thus obtaining the dried anode sheet. (4) In-situ curing The dried negative electrode obtained in step (3) is stacked sequentially with LLZO electrolyte and LiCoO2 positive electrode to form an unencapsulated button cell. The unencapsulated button cell is placed in an 85°C oven and heated for 1.5 hours to trigger PEGDA crosslinking and curing, forming a dense buffer layer that can resist lithium dendrite interfaces, thus obtaining a solid-state battery that can resist lithium dendrites.

[0023] Example 3 (1) Preparation of buffer layer slurry Li3PO4 particles were added to an organic solvent and ultrasonically dispersed at 180 W for 25 min to obtain a uniform Li3PO4 dispersion. Subsequently, PEGDA, LiTFSI, and FEC were added to the Li3PO4 dispersion in a mass ratio of 75:18:5:2. The mixture was stirred at 600 r / min for 1.5 h in an inert gas atmosphere to obtain a buffer layer slurry. The viscosity of the buffer layer slurry was 120 cps, the inert gas was argon, the organic solvent was acetonitrile, and the particle size of the Li3PO4 particles was 100 nm.

[0024] (2) Interface coating The buffer layer slurry obtained in step (1) is uniformly coated onto the surface of the lithium metal anode using a doctor blade coating method to obtain the coated lithium metal anode; the coating thickness is 15 μm.

[0025] (3) Pre-drying The coated lithium metal anode obtained in step (2) was placed in a vacuum oven at 35°C and dried for 1.5 h to remove the organic solvent, thus obtaining the dried anode sheet. (4) In-situ curing The dried negative electrode obtained in step (3) is stacked sequentially with LLZO electrolyte and LiCoO2 positive electrode to form an unencapsulated button cell. The unencapsulated button cell is placed in an 85°C oven and heated for 1.5 hours to trigger PEGDA crosslinking and curing, forming a dense buffer layer that can resist lithium dendrite interfaces, thus obtaining a solid-state battery that can resist lithium dendrites.

[0026] Example 4 (1) Preparation of buffer layer slurry Li3PO4 particles were added to an organic solvent and ultrasonically dispersed at 180 W for 25 min to obtain a uniform Li3PO4 dispersion. Subsequently, PEGDA, LiTFSI, and FEC were added to the Li3PO4 dispersion in a mass ratio of 60:30:8:2. The mixture was stirred at 600 r / min for 1.5 h in an inert gas atmosphere to obtain a buffer layer slurry. The viscosity of the buffer layer slurry was 120 cps, the inert gas was argon, the organic solvent was acetonitrile, and the particle size of the Li3PO4 particles was 100 nm.

[0027] (2) Interface coating The buffer layer slurry obtained in step (1) is uniformly coated onto the surface of the lithium metal anode using a doctor blade coating method to obtain the coated lithium metal anode; the coating thickness is 8 μm.

[0028] (3) Pre-drying The coated lithium metal anode obtained in step (2) was placed in a vacuum oven at 35°C and dried for 1.5 h to remove the organic solvent, thus obtaining the dried anode sheet. (4) In-situ curing The dried negative electrode obtained in step (3) is stacked sequentially with LLZO electrolyte and LiCoO2 positive electrode to form an unencapsulated button cell. The unencapsulated button cell is placed in an 85°C oven and heated for 1.5 hours to trigger PEGDA crosslinking and curing, forming a dense buffer layer that can resist lithium dendrite interfaces, thus obtaining a solid-state battery that can resist lithium dendrites.

[0029] Example 5 (1) Preparation of buffer layer slurry Li3PO4 particles were added to an organic solvent and ultrasonically dispersed at 180 W for 25 min to obtain a uniform Li3PO4 dispersion. Subsequently, PEGDA, LiTFSI, and FEC were added to the Li3PO4 dispersion in a mass ratio of 74:18:6:2. The mixture was stirred at 600 r / min for 1.5 h in an inert gas atmosphere to obtain a buffer layer slurry. The viscosity of the buffer layer slurry was 120 cps, the inert gas was argon, the organic solvent was acetonitrile, and the particle size of the Li3PO4 particles was 100 nm.

[0030] (2) Interface coating The buffer layer slurry obtained in step (1) is uniformly coated onto the surface of the lithium metal anode using a doctor blade coating method to obtain the coated lithium metal anode; the coating thickness is 55 μm.

[0031] (3) Pre-drying The coated lithium metal anode obtained in step (2) was placed in a vacuum oven at 35°C and dried for 1.5 h to remove the organic solvent, thus obtaining the dried anode sheet. (4) In-situ curing The dried negative electrode obtained in step (3) is stacked sequentially with LLZO electrolyte and LiCoO2 positive electrode to form an unencapsulated button cell. The unencapsulated button cell is placed in an 85°C oven and heated for 1.5 hours to trigger PEGDA crosslinking and curing, forming a dense buffer layer that can resist lithium dendrite interfaces, thus obtaining a solid-state battery that can resist lithium dendrites.

[0032] Example 6 (1) Preparation of buffer layer slurry Li3PO4 particles were added to an organic solvent and ultrasonically dispersed at 180 W for 25 min to obtain a uniform Li3PO4 dispersion. Subsequently, PEGDA, LiTFSI, and FEC were added to the Li3PO4 dispersion in a mass ratio of 70:20:8:2. The mixture was stirred at 600 r / min for 1.5 h in an inert gas atmosphere to obtain a buffer layer slurry. The viscosity of the buffer layer slurry was 120 cps, the inert gas was argon, the organic solvent was acetonitrile, and the particle size of the Li3PO4 particles was 100 nm.

[0033] (2) Interface coating The buffer layer slurry obtained in step (1) is uniformly coated onto the surface of the lithium metal anode using a doctor blade coating method to obtain the coated lithium metal anode; the coating thickness is 10 μm.

[0034] (3) Pre-drying The coated lithium metal anode obtained in step (2) was placed in a vacuum oven at 35°C and dried for 1.5 h to remove the organic solvent, thus obtaining the dried anode sheet. (4) In-situ curing The dried negative electrode obtained in step (3) is stacked sequentially with LLZO electrolyte and LiCoO2 positive electrode to form an unencapsulated button cell. The unencapsulated button cell is placed in an 85°C oven and heated for 1.5 hours to trigger PEGDA crosslinking and curing, forming a dense buffer layer that can resist lithium dendrite interfaces, thus obtaining a solid-state battery that can resist lithium dendrites.

[0035] Comparative Example 1 Using conventional all-solid-state battery manufacturing processes, without setting any interface buffer layer, the lithium metal anode, LLZO electrolyte, and LiCoO2 cathode are directly stacked in sequence to assemble a solid-state button battery; the LLZO electrolyte is prepared using a traditional high-temperature sintering process, that is, sintering at 1100°C for 6 hours, and other conditions and parameters are consistent with those in Example 1.

[0036] Performance tests were conducted on the above embodiments, and the test results are shown in Table 1.

[0037]

[0038] Table 1 Analysis of the above data shows that the solid-state batteries prepared by the method of the present invention have excellent performance. The performance of Examples 1-6 is far superior to that of Comparative Example 1. Examples 1-6 have high ionic conductivity, excellent cycle performance, and can suppress lithium dendrite growth. After 500 cycles, the length can be only 3μm, reducing the probability of battery short circuit to as low as 0.5%. In addition, the interface impedance is low, which greatly improves the interfacial compatibility and long-term stability of the electrolyte and lithium anode, and achieves remarkable progress.

[0039] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a solid-state battery resistant to lithium dendrite formation, characterized in that: It includes the following steps: (1) Preparation of buffer layer slurry Li3PO4 particles were added to an organic solvent and ultrasonically dispersed at 180 W for 25 min to obtain a uniform Li3PO4 dispersion. Subsequently, PEGDA, LiTFSI and FEC were added to the Li3PO4 dispersion. The mass ratio of Li3PO4 particles, PEGDA, LiTFSI and FEC was (60-75):(18-30):(5-8):

2. The mixture was stirred at 600 r / min for 1.5 h in an inert gas atmosphere to obtain a buffer layer slurry. (2) Interface coating The buffer layer slurry obtained in step (1) is uniformly coated onto the surface of the lithium metal anode by means of coating, so as to obtain the coated lithium metal anode. (3) Pre-drying The coated lithium metal anode obtained in step (2) was placed in a vacuum oven at 35°C and dried for 1.5 h to remove the organic solvent, thus obtaining the dried anode sheet. (4) In-situ curing The dried negative electrode obtained in step (3) is stacked sequentially with LLZO electrolyte and LiCoO2 positive electrode to form an unencapsulated button cell. The unencapsulated button cell is placed in an 85°C oven and heated for 1.5 hours to trigger PEGDA crosslinking and curing, forming a dense buffer layer that can resist lithium dendrite interfaces, thus obtaining a solid-state battery that can resist lithium dendrites.

2. The method for preparing a solid-state battery resistant to lithium dendrites according to claim 1, characterized in that: In step (1), the viscosity of the buffer layer slurry is 120 cps.

3. The method for preparing a solid-state battery resistant to lithium dendrites according to claim 1, characterized in that: In step (1), the inert gas is argon.

4. The method for preparing a solid-state battery resistant to lithium dendrites according to claim 1, characterized in that: In step (1), the organic solvent is acetonitrile.

5. The method for preparing a solid-state battery resistant to lithium dendrites according to claim 1, characterized in that: In step (1), the particle size of the Li3PO4 particles is 100 nm.

6. The method for preparing a solid-state battery resistant to lithium dendrites according to claim 1, characterized in that: In step (2), the buffer layer slurry obtained in step (1) is uniformly coated on the surface of the lithium metal anode by using a doctor blade coating method to obtain the coated lithium metal anode.

7. The method for preparing a solid-state battery resistant to lithium dendrites according to claim 1, characterized in that: In step (2), the coating thickness is 3-15 μm.

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