An Al2O3 skeleton electrode sheet containing LiAlO2 / LiNbO3 double cladding layers and a sulfide solid-state lithium battery composite electrode

Abstract

The application provides an Al2O3 skeleton electrode sheet containing LiAlO2 / LiNbO3 double-coated layers and a sulfide solid-state lithium battery composite electrode, and belongs to the technical field of sulfide solid-state lithium batteries. + The application adopts an atomic layer deposition process to construct double-layer functional coating on the Al2O3 skeleton, wherein the inner layer LiAlO2 serves as a chemical barrier layer and can inhibit the reaction of sulfides and Al2O3, and the outer layer LiNbO3 serves as an ion conductor layer and can reduce the Li diffusion energy barrier. The application solves the problems of chemical side reactions and too high lithium ion migration energy barrier of the electrode / skeleton material and electrolyte interface by decoupling the barrier-conduction function of the LiAlO2 and LiNbO3 double-coated layers, taking the thermodynamic stable phase (LiAlO2) as an interface sacrificial layer, and utilizing the topological ion transport characteristics of the niobium-oxygen octahedral channel, so that the unity of interface chemical stability and ion conductivity is realized in sub-nanometer scale.

Description

Technical Field

[0001] This invention relates to the field of sulfide solid-state lithium battery technology, specifically to an Al2O3 framework electrode sheet containing a LiAlO2 / LiNbO3 double coating layer and a sulfide solid-state lithium battery composite electrode. Background Technology

[0002] Sulfide solid-state lithium batteries are lithium batteries that use solid sulfide materials as electrolytes, completely replacing traditional liquid electrolytes. Sulfide solid-state lithium batteries exhibit extremely high ionic conductivity, and some sulfide electrolytes (such as Li6PS5Cl, Li...)... 10 GeP2S 12 The lithium-ion conductivity of sulfide solid electrolytes can reach 10 mS / cm at room temperature, which is close to or even exceeds that of traditional liquid electrolytes. This means that lithium ions can migrate rapidly inside the solid, ensuring the high power performance of the battery. Although sulfide solid electrolytes have ultra-high ionic conductivity, the following challenges still exist when they come into contact with oxide frameworks (such as Al2O3 framework): ① Chemical side reactions: During the infiltration of molten sulfide, sulfur (S... 2- The reaction of Al2O3 with Al2O3 forms an insulating interface layer (also known as a secondary reaction layer, which contains A). l2 S3, Li-Al-SO compounds), blocking ion transport channels; ② High energy barrier interface: a strong space charge layer exists at the sulfide / oxide interface, leading to Li + The migration barrier is 0.5 eV, which significantly increases the interfacial impedance.

[0003] Traditional methods for modifying the Al2O3 framework involve depositing a monolayer of LiNbO3 onto the Al2O3 framework surface. However, this method cannot suppress the deep reaction between Al2O3 and sulfides, and the thickness of the by-reaction layer is often higher than 3-5 nm. Depositing Li3PO4 on the Al2O3 framework surface also presents challenges, as Li... + The migration barrier is still 0.45 eV, which cannot completely eliminate the space charge layer at the interface. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide an Al2O3 framework electrode sheet containing a LiAlO2 / LiNbO3 double coating layer and a sulfide solid-state lithium battery composite electrode. The Al2O3 framework electrode sheet with a double coating layer provided by this invention can solve the problems of chemical side reactions at the electrode / framework material-electrolyte interface and excessively high lithium-ion migration barriers in sulfide solid-state lithium batteries, avoiding sulfide / oxide interface failure, thereby promoting the industrialization of next-generation batteries with an energy density of 400Wh / kg.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides an Al2O3 framework electrode sheet containing a LiAlO2 / LiNbO3 double coating layer, comprising an Al2O3 framework and a LiAlO2 layer and a LiNbO3 layer sequentially atomically deposited on the surface of the Al2O3 framework; The thickness of the LiAlO2 layer is 2~5nm; the thickness of the LiNbO3 layer is 1~3nm.

[0006] Preferably, the porosity of the Al2O3 framework is 60±5%, the pore size is 1~5μm, and the thickness of the Al2O3 framework is 150~300μm.

[0007] This invention provides a method for preparing the Al2O3 framework electrode sheet containing the above-mentioned LiAlO2 / LiNbO3 double coating layer, comprising the following steps: The Al2O3 framework was mixed with Piranha solution and then subjected to ultrasonic cleaning, rinsing and drying to obtain a pretreated Al2O3 framework. LiAlO2 is deposited on the surface of the pretreated Al2O3 framework to obtain a LiAlO2 layer on the surface of the pretreated Al2O3 framework. LiNbO3 is atomically deposited on the surface of the LiAlO2 layer to obtain the Al2O3 framework electrode sheet containing the LiAlO2 / LiNbO3 double coating layer.

[0008] Preferably, the ultrasonic cleaning frequency is 35~45kHz and the power density is 40~60W / L; the ultrasonic cleaning temperature is 60±2℃ and the time is 30±1min. The rinsing solution used for rinsing is ultrapure water; The drying process is vacuum drying, and the drying temperature is 80~120℃; The hydroxyl density of the pretreated Al2O3 framework is ≥5 hydroxyl groups / nm. 2 The water contact angle θ ≤ 10°.

[0009] Preferably, the precursor for atomic layer deposition of LiAlO2 comprises trimethylaluminum, lithium tert-butoxide solution, and O3, wherein the concentration of lithium tert-butoxide solution is 0.10 ± 0.01 mol / L, and the concentration of O3 is 150 ± 5 g / m³. 3 ; The single-cycle timing sequence for atomic layer deposition of LiAlO2 is as follows: trimethylaluminum pulse 0.02s → Ar purge 10s → O3 pulse 0.5s → Ar purge 15s → lithium tert-butoxide solution pulse 1.0s → Ar purge 20s; the total number of cycles is 50~150. The atomic layer deposition temperature of LiAlO2 was 180±2℃, and the Li / Al molar ratio was 1.0±0.1.

[0010] Preferably, the precursor for the atomic layer deposition of LiNbO3 includes niobium pentaethoxy, lithium tert-butoxide, and water; The single-cycle timing sequence for atomic layer deposition of LiNbO3 is as follows: niobium pentaethoxy pulse 0.5s → Ar purge 15s → H2O pulse 0.1s → Ar purge 15s → lithium tert-butoxide pulse 0.8s → Ar purge 20s; the total number of cycles is 30~100. The atomic layer deposition temperature of LiNbO3 was 150±2℃, the vaporization pressure of H2O was 10.0±0.5 Torr, and the Nb / Li molar ratio was 1:1.05.

[0011] Preferably, before the atomic layer deposition of LiNbO3, the LiAlO2 layer is further subjected to plasma activation. The gas used for plasma activation is an Ar / H2 mixture, the volume ratio of Ar to H2 in the Ar / H2 mixture is 90~95:5~10, the power of plasma activation is 40~60W, and the time is 20~40s. After the atomic layer deposition of LiNbO3, the process further includes an interface passivation treatment of the resulting LiNbO3 layer. The interface passivation treatment includes sequentially introducing O2 and Ar to purge the surface of the LiNbO3 layer, with the O2 introduction time being 0.1s and the Ar introduction time being 30s.

[0012] The present invention provides a sulfide solid-state lithium battery composite electrode, comprising an Al2O3 framework electrode sheet containing a LiAlO2 / LiNbO3 double coating layer, and a sulfide electrolyte that is hot-pressed into the LiNbO3 side surface and pores of the Al2O3 framework electrode sheet containing the LiAlO2 / LiNbO3 double coating layer.

[0013] This invention provides a method for preparing the above-mentioned sulfide solid-state lithium battery composite electrode, comprising the following steps: An Al2O3 framework electrode sheet containing a LiAlO2 / LiNbO3 double coating layer is subjected to hot-pressing infiltration and cooling with a sulfide electrolyte to obtain the sulfide solid-state lithium battery composite electrode and the sulfide electrolyte layer on the surface of the sulfide solid-state lithium battery composite electrode. The hot pressing temperature is 200±5℃, the pressure is 20±1MPa, and the heat and pressure holding time is 30±1min.

[0014] This invention provides the application of the above-mentioned sulfide solid-state lithium battery composite electrode in sulfide solid-state lithium batteries.

[0015] This invention provides an Al2O3 framework electrode sheet containing a LiAlO2 / LiNbO3 double coating layer, comprising an Al2O3 framework and a LiAlO2 layer and a LiNbO3 layer sequentially atomically deposited on the surface of the Al2O3 framework; the thickness of the LiAlO2 layer is 2-5 nm; and the thickness of the LiNbO3 layer is 1-3 nm. This invention employs atomic layer deposition (ALD) to construct a double functional coating on the Al2O3 framework, wherein the inner LiAlO2 layer (2-5 nm) acts as a chemical barrier layer, inhibiting the reaction between sulfides and Al2O3, and the outer LiNbO3 layer (1-3 nm) acts as an ion conductor layer, reducing the Li... + Diffusion barrier. LiAlO2 and LiNbO3 have extremely high lattice matching, with a mismatch rate of <2%, ensuring a crack-free interface. Other combinations, such as LiAlO2 / Li3PO4, have a mismatch rate of 5%, which easily leads to interface failure. This invention utilizes the barrier-conduction function of the LiAlO2 and LiNbO3 double-coating layer to decouple the layers, using the thermodynamically stable phase (LiAlO2) as an interface sacrificial layer. By leveraging the topological ion transport properties of niobium-oxygen octahedral channels, the thickness of the side reaction layer can be reduced to ≤1 nm, and the ion migration barrier can be reduced to <0.3 eV, a reduction of up to 40% compared to existing technologies. The design of the LiAlO2 and LiNbO3 double-coating layer enables Li... + Cross-interface migration speed increased to 2.3×10 -7 cm 2 / s (single-layer LiNbO3 is only 8.5×10 -8 cm 2 / s), meeting the 5mA / cm requirement of all-solid-state batteries. 2 The present invention completely solves the problem of sulfide / oxide interface failure, achieving a balance between interfacial chemical stability and ionic conductivity at the sub-nanometer scale. The resulting Al2O3 framework electrode sheet is compatible with mainstream sulfide electrolytes (such as Li6PS5Cl, Li...). 10 GeP2S 12 This will help promote the industrialization of next-generation batteries with an energy density of 400Wh / kg.

[0016] This invention provides a method for preparing the Al2O3 framework electrode sheet containing a LiAlO2 / LiNbO3 double coating layer. The invention employs atomic layer deposition (ALD) technology, easily achieving sub-nanometer precision ALD control by controlling thickness fluctuations within ±0.1 nm. This results in a coating layer thickness error of <±5%, an interdiffusion depth between LiAlO2 and LiNbO3 layers of ≤0.3 nm, and zero coating layer peeling during molten sulfur penetration testing (200℃). It can directly match mass production process conditions and is compatible with roll-to-roll ALD equipment (such as the Beneq TFS200), with a theoretical production capacity of 100,000 m³. 2 / Year.

[0017] This invention provides a sulfide-based solid-state lithium battery composite electrode, comprising an Al2O3 framework electrode sheet containing a LiAlO2 / LiNbO3 double coating layer, and a sulfide electrolyte hot-pressed into the LiNbO3 side surface and pores of the Al2O3 framework electrode sheet containing the LiAlO2 / LiNbO3 double coating layer. This invention integrates molten sulfur infiltration and densification through hot pressing, achieving complete infiltration of the sulfide electrolyte into the coated framework, thereby constructing a low-impedance interface battery. After sulfide filling, the resulting composite electrode exhibits a pore filling rate ≥99% and an interfacial contact resistance ≤2Ω·cm. 2 The sulfur distribution uniformity RSD is ≤5%, and the areal specific capacity is 5.2 mAh / cm³. 2 @0.5C (commercial requirements: 4mAh / cm) 2 The energy efficiency is ≥99% (polarization voltage <10mV). The constructed sulfide solid-state lithium battery exhibits a 5C capacity / 0.1C capacity ratio ≥85% under 0.1C→5C charge / discharge conditions, and a capacity retention rate ≥90% after 2000 cycles in a long-term cycle stability test at 0.5C @25℃. The sulfide solid-state lithium battery composite electrode provided by this invention can increase battery energy density to 400Wh / kg (a 33% increase from the current 300Wh / kg), supports 5C fast charging (80% charge in 10 minutes), and has a cycle cost <$0.01 / cycle (2000 cycle life). This invention utilizes the aforementioned sulfide solid-state lithium battery composite electrode in sulfide solid-state lithium batteries, eliminating the risk of liquid electrolyte leakage / combustion, resulting in low carbon emissions during production and use, and offering high economic benefits and environmental advantages. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the sulfide solid-state lithium battery composite electrode of the present invention. Detailed Implementation

[0019] This invention provides an Al2O3 framework electrode sheet containing a LiAlO2 / LiNbO3 double coating layer, comprising an Al2O3 framework and a LiAlO2 layer and a LiNbO3 layer sequentially atomically deposited on the surface of the Al2O3 framework. In this invention, the Al2O3 framework is preferably a porous Al2O3 framework, with a porosity preferably of 60±5% and a pore size preferably of 1~5 μm; the thickness of the Al2O3 framework is preferably 150~300 μm, more preferably 200~250 μm. In this invention, the thickness of the LiAlO2 layer is preferably 2~5 nm, more preferably 3~4 nm; the thickness of the LiNbO3 layer is preferably 1~3 nm, more preferably 2~3 nm.

[0020] This invention provides a method for preparing the Al2O3 framework electrode sheet containing the above-mentioned LiAlO2 / LiNbO3 double coating layer, comprising the following steps: The Al2O3 framework was mixed with Piranha solution and then subjected to ultrasonic cleaning, rinsing and drying to obtain a pretreated Al2O3 framework. LiAlO2 is deposited on the surface of the pretreated Al2O3 framework to obtain a LiAlO2 layer on the surface of the pretreated Al2O3 framework. LiNbO3 is atomically deposited on the surface of the LiAlO2 layer to obtain the Al2O3 framework electrode sheet containing the LiAlO2 / LiNbO3 double coating layer.

[0021] This invention involves mixing an Al2O3 framework with a Piranha solution, followed by ultrasonic cleaning, rinsing, and drying to obtain a pretreated Al2O3 framework. In this invention, the Piranha solution is prepared from concentrated sulfuric acid and 30% hydrogen peroxide, with a preferred volume ratio of 3:1. The Piranha solution must be prepared fresh and has a shelf life of <4 hours. This invention does not have specific requirements on the amount of Piranha solution used; it only needs to be sufficient to submerge the Al2O3 framework. This invention removes organic residues through the strong oxidizing effect of the Piranha solution; the reaction that occurs is C... x H y +H2O2→CO2+H2O.

[0022] In this invention, the Al2O3 framework is preferably placed in a polytetrafluoroethylene (PTFE) carrier basket for ultrasonic cleaning, and the loading density of the Al2O3 framework is preferably ≤0.2 g / cm³. 3 To avoid the ultrasonic shielding effect, the ultrasonic cleaning equipment used in this invention is preferably an ultrasonic cleaner, preferably a Branson 5800. The ultrasonic cleaning frequency is preferably 35~45kHz, more preferably 40kHz, and the power density is 40~60W / L, more preferably 50W / L; the ultrasonic cleaning temperature is 60±2℃, and the time is 30±1min. This invention, through ultrasonic cleaning, facilitates atomic-level surface cleaning and chemical activation, ensuring a uniform and dense ALD coating layer.

[0023] In this invention, the rinsing solution used is ultrapure water, and the resistivity of the ultrapure water is preferably 18.2 MΩ·cm. In this invention, the rinsing is preferably gradient rinsing, and the preferred gradient rinsing procedure is shown in Table 1.

[0024] Table 1 Gradient rinsing procedure

[0025] In this invention, after the gradient rinsing, the change in conductivity of the rinsing water is ≤0.1 μS / cm. This invention, through the rinsing process, can eliminate acid residue (the residual liquid on the Al2O3 framework surface after washing has a pH of 6.5~7.5).

[0026] In this invention, the drying is preferably vacuum drying, and the vacuum drying oven used is preferably a Thermo Scientific Heratherm model with an ultimate vacuum of 5 × 10⁻⁶. -4 Pa, temperature control accuracy ±0.5℃. In this invention, the drying temperature is preferably 80~120℃, and the vacuum degree is preferably ≤10. -3 Pa, the preferred drying time is 2 ± 0.5 h. This invention removes adsorbed water through drying, resulting in an adsorbed H2O content < 0.1 ppm, while simultaneously controlling the hydroxyl density of the pretreated Al2O3 framework. In this invention, the drying temperature of 120℃ is significantly lower than the hydroxyl desorption threshold (300℃) on the Al2O3 surface, avoiding the formation of Lewis acid sites (Al... 3+ Exposure leads to increased sulfur reactivity.

[0027] In this invention, the hydroxyl density of the pretreated Al2O3 framework is ≥5 hydroxyl groups / nm. 2 The water contact angle θ ≤ 10°. In this invention, the ultrasonic cleaning, rinsing, and drying processes are carried out under an inert atmosphere, preferably Ar gas, and the oxygen content of the inert gas is preferably ≤ 0.01 ppm.

[0028] After obtaining the pretreated Al2O3 framework, the present invention performs atomic layer deposition of LiAlO2 on the surface of the pretreated Al2O3 framework to obtain a LiAlO2 layer on the surface of the pretreated Al2O3 framework. The atomic layer deposition is performed in an ALD reaction chamber, preferably a Beneq TFS500 with a substrate size of Φ200mm, temperature control accuracy of ±0.1℃, and compatibility with porous framework loading. Before the LiAlO2 atomic layer deposition, the reaction chamber is preferably pretreated. The pretreatment preferably includes sequential vacuum baking and in-situ plasma cleaning. The vacuum baking temperature is preferably 200℃, and the vacuum degree is 5×10⁻⁶. -6 Pa, time is 1h; the gas for in-situ plasma cleaning is preferably an Ar / O2 mixture, the volume ratio of Ar / O2 is preferably 4:1, the power of in-situ plasma cleaning is preferably 300W, and the time is preferably 5min.

[0029] In this invention, the precursor for atomic layer deposition of LiAlO2 preferably comprises trimethylaluminum (TMA), lithium tert-butoxide solution (LiOtBu), and O3. The concentration of the lithium tert-butoxide solution is preferably 0.10 ± 0.01 mol / L, and the concentration of O3 is preferably 150 ± 5 g / m³. 3 The present invention preferably uses an ultrasonic atomization injection system to deliver the precursor, wherein the droplet size of the delivered precursor is ≤5μm and the flow rate stability is ±1%, to ensure uniform vaporization of LiOtBu.

[0030] In this invention, the preferred single-cycle timing for atomic layer deposition of LiAlO2 is: trimethylaluminum pulse 0.02s → Ar purge 10s → O3 pulse 0.5s → Ar purge 15s → lithium tert-butoxide solution pulse 1.0s → Ar purge 20s; the total number of cycles is preferably 50-150 times, more preferably 80-120 times. In this invention, during the atomic layer deposition of LiAlO2, the reaction process of TMA and -OH is: Al(CH3)3 + Al-OH → Al-O-Al(CH3)2 + CH4, with O3 oxidation to generate Al-O bonds. This invention uses LiOtBu post-deposition (TMA + O3 first forms the Al-O framework, then Li is injected). + It can avoid lithium volatilization at high temperatures, avoid insufficient purging leading to gas phase nucleation through single-cycle program control, and maintain the thickness of LiAlO2 layer at 2~5nm by controlling the total number of cycles.

[0031] This invention, by controlling the specific conditions of atomic layer deposition of LiAlO2, enables the LiAlO2 layer to maintain structural integrity in a molten sulfur environment at 200℃, achieving a side reaction suppression efficiency of 99.5% (8 nm for uncoated samples with a side reaction layer). Compared to the H2O oxidation process, this invention uses O3 as the oxide, resulting in the reaction: 2Al(CH3)3 + 3O3 → Al2O3 + 6CH4 + 3O2↑, which can increase the density of the LiAlO2 layer to 3.4 g / cm³. 3 The sulfur permeability decreased by 80%, while the H2O process resulted in only 2.9 g / cm³. 3 .

[0032] In this invention, the preferred temperature for atomic layer deposition of LiAlO2 is 180±2℃, and the preferred Li / Al molar ratio is 1.0±0.1. By controlling the atomic layer deposition temperature of LiAlO2 to 180±2℃, this invention ensures that LiOtBu decomposes fully without volatilizing, avoids the decomposition of LiOtBu at 190℃ to generate Li2CO3 impurities and carbon pollution, and also avoids the decrease in deposition efficiency when the deposition temperature is <170℃.

[0033] In this invention, during the atomic layer deposition of LiAlO2, a high-purity Ar gas path (6N) is used in the ambient atmosphere, and the O2 / H2O content is ≤10ppb to prevent LiAlO2 from being oxidized to LiAlO. 2.5 .

[0034] After obtaining the LiAlO2 layer, the present invention performs atomic layer deposition of LiNbO3 on the surface of the LiAlO2 layer to obtain the Al2O3 framework electrode sheet containing the LiAlO2 / LiNbO3 double coating layer. In this invention, before the atomic layer deposition of LiNbO3, the present invention preferably includes plasma activation of the LiAlO2 layer. The gas used for plasma activation is preferably an Ar / H2 mixture, the volume ratio of Ar to H2 in the Ar / H2 mixture is preferably 90~95:5~10, more preferably 95:5, the power of the plasma activation is preferably 40~60W, more preferably 50W, and the time is preferably 20~40s, more preferably 30s. The present invention achieves interface activation of the LiAlO2 layer through plasma activation to eliminate the passivation layer on the LiAlO2 surface and expose the -O active sites.

[0035] In this invention, the precursor for atomic layer deposition of LiNbO3 comprises niobium pentaethoxy, lithium tert-butoxide, and water. In this invention, the precursor vaporizer used for atomic layer deposition is preferably a Picosun R-200 Booster, which enables the Nb(OEt)5 to vaporize at a temperature of 120 ± 1 °C, preventing the formation of oligomers with a molecular weight ≤ 300 Da. In this invention, the water is preferably deionized water; insufficient water purity can easily lead to Nb2O5 phase separation.

[0036] In this invention, the preferred single-cycle timing for atomic layer deposition of LiNbO3 is: 0.5s niobium pentaethoxy pulse → 15s Ar purge → 0.1s H2O pulse → 15s Ar purge → 0.8s lithium tert-butoxide pulse → 20s Ar purge; the total number of cycles is preferably 30-100 times, more preferably 50-80 times. In this invention, during the atomic layer deposition of LiNbO3, Nb(OEt)5 undergoes a hydrolysis reaction: Nb(OC2H5)5 + H2O → NbO(OC2H5)3 + 2C2H5OH, Li + By embedding niobium-oxygen octahedral channels, this invention controls the single-cycle timing of atomic layer deposition of LiNbO3, employing a method of Nb(OEt)5 hydrolysis followed by lithiation, which can reduce Cl... - The content, capable of converting Cl -The content is <0.1 at%. This invention employs stepwise hydrolysis, which avoids liquid phase residue. When LiOtBu is deposited in excess, it can easily lead to a decrease in electronic conductivity. This invention maintains the thickness of LiNbO3 at 1~3 nm by controlling the total number of cycles N. When N < 25, it can easily lead to incomplete coverage, and when N > 110, it can easily lead to electron tunneling blockage.

[0037] In this invention, the preferred temperature for atomic layer deposition of LiNbO3 is 150±2℃, the preferred vaporization pressure of H2O is 10.0±0.5 Torr, and the preferred Nb / Li molar ratio is 1:1.05. By controlling the atomic layer deposition temperature, this invention maintains the amorphous structure and maximizes ionic conductivity. When the atomic layer deposition temperature reaches 160℃, crystallization easily occurs, raising the energy barrier to 0.1 eV. By controlling the H2O vaporization pressure to 10.0±0.5 Torr, this invention ensures complete surface hydroxylation.

[0038] In this invention, after the atomic layer deposition of LiNbO3, the process preferably further includes an interface passivation treatment of the resulting LiNbO3 layer. The interface passivation treatment includes sequentially introducing O2 and Ar to purge the surface of the LiNbO3 layer, with the O2 introduction time preferably being 0.1 s and the Ar introduction time preferably being 30 s. This invention, through the interface passivation treatment, can repair oxygen vacancies.

[0039] The present invention provides a sulfide solid-state lithium battery composite electrode, comprising an Al2O3 framework electrode sheet containing a LiAlO2 / LiNbO3 double coating layer, and a sulfide electrolyte that is hot-pressed into the LiNbO3 side surface and pores of the Al2O3 framework electrode sheet containing the LiAlO2 / LiNbO3 double coating layer.

[0040] In this invention, the sulfide electrolyte is preferably Li6PS5Cl and / or Li 10 GeP2S 12 In this invention, the mass ratio of the Al2O3 framework electrode sheet containing the LiAlO2 / LiNbO3 double coating layer to the sulfide electrolyte is preferably 1:1~2, more preferably 1:1.5.

[0041] This invention provides a method for preparing the above-mentioned sulfide solid-state lithium battery composite electrode, comprising the following steps: An Al2O3 framework electrode sheet containing a LiAlO2 / LiNbO3 double coating layer is subjected to hot-pressing infiltration and cooling with a sulfide electrolyte to obtain the sulfide solid-state lithium battery composite electrode and the sulfide electrolyte layer on the surface of the sulfide solid-state lithium battery composite electrode. In this invention, the D of the sulfide electrolyte 50The particle size is preferably 5 μm. Before the hot-press permeation, the sulfide electrolyte is preferably pre-dried, preferably under vacuum conditions, at a temperature of 120°C for 24 hours.

[0042] The present invention preferably uses a hot-press sintering furnace for the hot-press infiltration process. The preferred model of the hot-press sintering furnace is FCTSystemeHPD25, with a maximum pressure of 50 MPa, temperature control accuracy of ±1°C, and vacuum degree of 10. -3 Pa. In this invention, the preferred temperature for hot-press infiltration is 200±5℃, the preferred pressure is 20±1MPa, and the preferred holding time is 30±1min. In this invention, during the hot-press infiltration process, the molten sulfide undergoes capillary infiltration, thereby achieving sulfide filling in the pores of the Al2O3 framework electrode sheet containing the LiAlO2 / LiNbO3 double coating layer.

[0043] In this invention, the thermo-pressure infiltration preferably employs a gradient thermo-pressure infiltration method, with a preferred pressurization rate of 5 MPa / min. The pressurization and heat preservation procedures for the gradient thermo-pressure infiltration in this invention are shown in Table 2. Table 2. Pressure boosting and heat preservation procedures for gradient thermal pressure infiltration.

[0044] This invention utilizes in-situ capillary permeation of molten sulfides to reduce the contact angle θ (the contact angle of the molten sulfide electrolyte on the surface of the Al2O3 framework electrode) of the composite electrode from 90° to <10°, thereby improving the electrode's sulfur affinity. By controlling the temperature and pressure of hot-press permeation, this invention achieves a 3-fold increase in permeation rate compared to traditional hot-pressing processes at 250°C and 10MPa, completing hot-press permeation in just 30 minutes. Furthermore, sulfur volatilization loss is reduced by 60%, and the porosity of the composite electrode is reduced by 80%.

[0045] The thickness of the sulfide electrolyte layer on the surface of the Al2O3 skeleton electrode sheet is preferably 450~550μm, more preferably 500μm.

[0046] This invention provides the application of the above-described sulfide solid-state lithium battery composite electrode in sulfide solid-state lithium batteries. In this invention, the sulfide solid-state lithium battery composite electrode is preferably used as the positive electrode of a sulfide solid-state lithium battery.

[0047] The following detailed description, in conjunction with embodiments, of the Al2O3 framework electrode sheet containing a LiAlO2 / LiNbO3 double coating layer and the sulfide solid lithium battery composite electrode provided by the present invention, should not be construed as limiting the scope of protection of the present invention.

[0048] Example 1 (I) The preparation of Al2O3 framework electrode sheets containing LiAlO2 / LiNbO3 double coating layers adopts the following steps: (1) Provide a porous Al2O3 framework with a porosity of 60±5% and a pore size of 1~5μm, and pretreat the Al2O3 framework as follows: Piranha ultrasonic cleaning (temperature 60℃, time 30min, frequency 40kHz) → Three-stage rinsing according to the procedure in Table 1 (ultrapure water rinsing, resistivity ≥18MΩ·cm) → Vacuum drying (120℃ / 2h).

[0049] (2) Vacuum baking of the ALD reaction chamber, specifically by evacuating the vacuum to 5×10 at 200℃. -6 Pa, maintained for 1 hour, followed by in-situ plasma cleaning: Ar / O2 mixed gas (ratio 4:1), power 300W, time 5 minutes.

[0050] LiAlO2 was atomically deposited on the surface of the pretreated Al2O3 framework. The precursors for the atomic layer deposition of LiAlO2 were TMA, LiOtBu (concentration of 0.10±0.01 mol / L), and O3 (concentration of 150±5 g / m³). 3 The single-cycle timing was as follows: TMA pulse 0.02s → Ar purge 10s → O3 pulse 0.5s → Ar purge 15s → LiOtBu pulse 1.0s → Ar purge 20s. The number of cycles (N) was 64. The single-layer thickness was 0.05nm / cycle. The total deposition thickness of the LiAlO2 layer was 3.2nm. The quartz crystal microbalance (QCM) calibrated thickness was 3.21nm (64th cycle).

[0051] (3) The obtained LiAlO2 layer is activated by plasma. The gas used for plasma activation is an Ar / H2 mixture with a volume ratio of Ar to H2 of 95:5. The plasma activation power is preferably 50W and the activation time is preferably 30s.

[0052] LiNbO3 was atomically deposited on the surface of the LiAlO2 layer using Nb(OEt)5, LiOtBu (Nb:Li molar ratio 1:1.05), and water (vaporization pressure 10.0±0.5 Torr) as precursors. The preferred single-cycle timing was: Nb(OEt)5 pulse 0.5s → Ar purging 15s → H2O pulse 0.1s → Ar purging 15s → LiOtBu pulse 0.8s → Ar purging 20s, with 60 cycles (N). The single-layer thickness was 0.03 nm / cycle, resulting in a total LiNbO3 layer thickness of 1.8±0.1 nm. After deposition, O2 was introduced for 0.1s → Ar purging for 30s to perform interface passivation and repair oxygen vacancies.

[0053] (II) Preparation of sulfide solid-state lithium battery composite electrode (S@Al2O3 coated framework) For sulfide Li6PS5Cl (D 50 Pre-drying (5μm) was carried out at 20℃ for 24h to ensure H2O content <8ppm. The Al2O3 framework electrode sheet containing the LiAlO2 / LiNbO3 double coating was then hot-pressed with pre-dried Li6PS5Cl at a mass ratio of 1:1.5 to obtain a sulfide solid-state lithium battery composite electrode. The hot-pressing process employed a gradient hot-pressing method: melting stage: 200℃ / 5MPa / 10min; penetration stage: 200℃ / 10→20MPa / 15min; densification stage: 200℃ / 20MPa / 5min.

[0054] A schematic diagram of the structure of the sulfide solid-state lithium battery composite electrode is shown below. Figure 1 As shown, Figure 1 In the diagram, the gray substrate represents the porous Al2O3 framework (pore size 1~5μm, porosity 60±5%), the green layer represents the inner LiAlO2 layer (thickness 3.2nm), which blocks sulfur diffusion, and the blue layer represents the outer LiNbO3 layer (thickness 1.8nm), which provides a low-energy barrier for Li. + The channels, filled in yellow, are sulfide electrolytes (Li6PS5Cl) used to completely fill the pores.

[0055] (III) Symmetrical battery assembly Assemble the symmetrical battery according to the structure in Table 3: Table 3 Symmetrical battery structure

[0056] The assembly pressure is 300MPa and the holding time is 5min; the encapsulation adopts Al plastic film vacuum encapsulation, and the residual gas pressure is <10Pa.

[0057] Performance metrics testing (1) The pretreated Al2O3 framework obtained in Example 1 was tested. The test indicators, methods, qualification standards and measured values ​​are shown in Table 4.

[0058] Table 4 Test results of pretreated Al2O3 framework

[0059] (2) The LiAlO2 layer obtained in Example 1 was tested. The test indicators, methods, qualification standards and measured values ​​are shown in Table 5.

[0060] Table 5 Test results of LiAlO2 layers

[0061] (3) The Al2O3 framework electrode sheet containing the LiAlO2 / LiNbO3 double coating layer in Example 1 was tested. The test indicators, methods, qualification standards and measured values ​​are shown in Table 6.

[0062] Table 6. Test results of Al2O3 framework electrode sheets with LiAlO2 / LiNbO3 double coating.

[0063] (4) The performance of the sulfide solid lithium battery composite electrode obtained in Example 1 and the assembled symmetrical battery were tested. The test items, results and comparison benchmarks are shown in Table 7.

[0064] Table 7 Performance test results of sulfide solid-state lithium battery composite electrode and assembled symmetric cell

[0065] Example 2: Thickness Boundary Verification The purpose of this embodiment is to test the lower limit of the coating thickness (LiAlO2=2.0nm, LiNbO3=1.0nm).

[0066] Compared with Example 1, the specific processes for atomic layer deposition of LiAlO2 and LiNbO3 layers are shown in Table 8.

[0067] Table 8. Relevant parameters of atomic layer deposition of LiAlO2 and LiNbO3 layers in Example 2

[0068] In addition, the O3 concentration was increased to 160 g / m³ during LiAlO2 deposition. 3 To enhance density, the LiOtBu pulse is increased to 1.0s during LiNbO3 deposition to compensate for insufficient thickness. During hot-pressing infiltration, the pressure is increased to 25MPa to ensure complete sulfur filling.

[0069] The obtained performance data are shown in Table 9: Table 9 Test data for Example 2

[0070] Example 3: Extreme Test of High-Temperature Molten Sulfur The purpose of this embodiment is to verify the stability of the coating layer under harsh conditions (molten sulfur at 220°C).

[0071] Compared with Example 1, the specific processes for atomic layer deposition of LiAlO2 and LiNbO3 layers are shown in Table 10.

[0072] Table 10 Relevant parameters of atomic layer deposition of LiAlO2 and LiNbO3 layers in Example 3

[0073] In addition, after LiAlO2 deposition, O3 post-treatment was added, with O3 0.2s → Ar purging for 30s to repair oxygen defects; the deposition temperature of LiNbO3 was reduced to 145℃ to strengthen the amorphous state.

[0074] The obtained performance data are shown in Table 11: Table 11 Test data for Example 3

[0075] As can be seen from Table 11, under extreme sulfur melting conditions of 220℃ / 2h, the present invention still maintains a side reaction layer of ≤1.5nm, verifying the robustness of the double coating layer under super-standard conditions.

[0076] The comparison results of Examples 1-3 are shown in Table 12: Table 12 Comparison results of Examples 1-3

[0077] In summary, the Al2O3 skeleton electrode sheet with double coating provided by this invention can solve the problems of chemical side reactions at the interface between electrode / skeleton materials and electrolyte and the excessively high lithium-ion migration barrier in sulfide solid lithium batteries, avoid sulfide / oxide interface failure, and thus promote the industrialization of next-generation batteries with an energy density of 400Wh / kg.

[0078] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An Al2O3 framework electrode sheet containing a LiAlO2 / LiNbO3 double coating layer, characterized in that, It includes an Al2O3 framework and LiAlO2 and LiNbO3 layers deposited sequentially on the surface of the Al2O3 framework at atomic layers; The thickness of the LiAlO2 layer is 2~5nm; the thickness of the LiNbO3 layer is 1~3nm.

2. The Al2O3 framework electrode sheet containing a LiAlO2 / LiNbO3 double coating layer according to claim 1, characterized in that, The Al2O3 framework has a porosity of 60±5% and a pore size of 1~5μm; the Al2O3 framework has a thickness of 150~300μm.

3. The method for preparing the Al2O3 framework electrode sheet containing a LiAlO2 / LiNbO3 double coating layer as described in claim 1 or 2, characterized in that, Includes the following steps: The Al2O3 framework was mixed with Piranha solution and then subjected to ultrasonic cleaning, rinsing and drying to obtain a pretreated Al2O3 framework. LiAlO2 is deposited on the surface of the pretreated Al2O3 framework to obtain a LiAlO2 layer on the surface of the pretreated Al2O3 framework. LiNbO3 is atomically deposited on the surface of the LiAlO2 layer to obtain the Al2O3 framework electrode sheet containing the LiAlO2 / LiNbO3 double coating layer.

4. The preparation method according to claim 3, characterized in that, The ultrasonic cleaning frequency is 35~45kHz, and the power density is 40~60W / L; the ultrasonic cleaning temperature is 60±2℃, and the time is 30±1min. The rinsing solution used for rinsing is ultrapure water; The drying process is vacuum drying, and the drying temperature is 80~120℃; The hydroxyl density of the pretreated Al2O3 framework is ≥5 hydroxyl groups / nm. 2 The water contact angle θ ≤ 10°.

5. The preparation method according to claim 3, characterized in that, The precursor for atomic layer deposition of LiAlO2 comprises trimethylaluminum, lithium tert-butoxide solution, and O3, wherein the concentration of lithium tert-butoxide solution is 0.10 ± 0.01 mol / L, and the concentration of O3 is 150 ± 5 g / m³. 3 ; The single-cycle timing sequence for atomic layer deposition of LiAlO2 is as follows: trimethylaluminum pulse 0.02s → Ar purge 10s → O3 pulse 0.5s → Ar purge 15s → lithium tert-butoxide solution pulse 1.0s → Ar purge 20s; the total number of cycles is 50~150. The atomic layer deposition temperature of LiAlO2 was 180±2℃, and the Li / Al molar ratio was 1.0±0.

1.

6. The preparation method according to claim 3, characterized in that, The precursor for atomic layer deposition of LiNbO3 includes niobium pentaethoxy, lithium tert-butoxide, and water; The single-cycle timing sequence for atomic layer deposition of LiNbO3 is as follows: niobium pentaethoxy pulse 0.5s → Ar purge 15s → H2O pulse 0.1s → Ar purge 15s → lithium tert-butoxide pulse 0.8s → Ar purge 20s; The total number of cycles is 30-100. The atomic layer deposition temperature of LiNbO3 was 150±2℃, the vaporization pressure of H2O was 10.0±0.5 Torr, and the Nb / Li molar ratio was 1:1.

05.

7. The preparation method according to claim 3, characterized in that, Before the atomic layer deposition of LiNbO3, the LiAlO2 layer is further subjected to plasma activation. The gas used for plasma activation is an Ar / H2 mixture, in which the volume ratio of Ar to H2 is 90~95:5~10. The power of plasma activation is 40~60W and the time is 20~40s. After the atomic layer deposition of LiNbO3, the process further includes an interface passivation treatment of the obtained LiNbO3 layer. The interface passivation treatment includes sequentially introducing O2 and Ar to purge the surface of the LiNbO3 layer. The O2 is introduced for 0.1 s and the Ar is introduced for 20 to 40 s.

8. A sulfide solid-state lithium battery composite electrode, characterized in that, The invention includes an Al2O3 framework electrode sheet containing a LiAlO2 / LiNbO3 double coating layer as described in claim 1 or 2, or an Al2O3 framework electrode sheet containing a LiAlO2 / LiNbO3 double coating layer prepared by the preparation method described in any one of claims 3 to 7, and a sulfide electrolyte that is hot-pressed into the LiNbO3 side surface and pores of the Al2O3 framework electrode sheet containing the LiAlO2 / LiNbO3 double coating layer.

9. The method for preparing the sulfide solid-state lithium battery composite electrode according to claim 8, characterized in that, Includes the following steps: An Al2O3 framework electrode sheet containing a LiAlO2 / LiNbO3 double coating layer is subjected to hot-pressing infiltration and cooling with a sulfide electrolyte to obtain the sulfide solid-state lithium battery composite electrode and the sulfide electrolyte layer on the surface of the sulfide solid-state lithium battery composite electrode. The hot pressing temperature is 200±5℃, the pressure is 20~25MPa, and the heat and pressure holding time is 30±1min.

10. The application of the sulfide solid-state lithium battery composite electrode of claim 8 or the sulfide solid-state lithium battery composite electrode prepared by the preparation method of claim 9 in sulfide solid-state lithium batteries.

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