Perovskite negative electrode with trifunctional interface structure and preparation method and application thereof

Abstract

The application belongs to the field of hydrogen negative ion batteries and solid-state energy storage technology, and discloses a perovskite negative electrode with a three-functional interface structure and a preparation method and application thereof. The perovskite negative electrode comprises a perovskite-based negative electrode active material, a lithium-based defect regulation layer arranged on the surface of the active material, a hydrogen negative ion transmission layer arranged on the surface of the defect regulation layer, and an electron conducting layer with a window region. The lithium-based defect regulation layer is used for optimizing the defect energy level on the surface of the active material and reducing the irreversible trapping of hydrogen negative ions; the hydrogen negative ion transmission layer is used for reducing the interface ion migration barrier between the active material and the solid-state electrolyte; and the electron conducting layer is used for providing an electron transmission path and retaining a hydrogen negative ion channel. Through the synergistic effect of the three functional layers, the first cycle coulombic efficiency, the rate performance and the cycle stability of the battery are improved.

Description

Technical Field

[0001] This invention relates to the fields of hydrogen negative ion batteries and solid-state energy storage technology, and in particular to a perovskite negative electrode with a three-functional interface structure, its preparation method and application. Background Technology

[0002] The gas-solid hydrogen negative ion battery uses gaseous hydrogen as the positive electrode active material and a solid electrolyte capable of conducting hydrogen negative ions as the ion transport medium. It achieves the coupling conversion between hydrogen energy and electrical energy through the reversible containment or release of hydrogen negative ions at the negative electrode. This system possesses the potential for both high energy density and solid-state safety, representing an important development direction in the field of electrochemical energy storage.

[0003] Perovskite defect oxides, perovskite hydrides, and double perovskite hydrides possess tunable A-sites, B-sites, and anion sites, enabling them to accommodate hydride anions via oxygen vacancies, anion vacancies, interstitial sites, or hydrogen vacancies. Compared to anodes based on the overall magnesium / magnesium hydride conversion reaction, perovskite-based anodes can achieve hydrogen storage and release through local lattice site occupation, insertion / deintercalation, or anion exchange processes, avoiding repeated migrations at large-scale metal / metal hydride phase interfaces. Therefore, they exhibit better structural stability and cycling potential.

[0004] However, using only perovskite-based anodes with reversible hydrogen anion-accommodating sites still faces the following technical challenges.

[0005] First, perovskite particles contain both shallow and deep defect sites on their surface and near-surface regions. Shallow defect sites enable reversible occupancy and release of hydride anions, while deep defect sites exhibit excessively strong binding forces to hydride anions, leading to irreversible trapping, resulting in initial capacity loss and increased residual hydrogen content during charging. When the number of oxygen or anion vacancies is insufficient, there are not enough sites available for hydride anions; conversely, excessively high defect concentrations or strong local structural distortions easily lead to the formation of deep traps, defect clusters, and irreversible hydrogenation regions. Simply increasing the number of defects cannot guarantee the reversibility of hydride anions; selective modulation of defect energy levels is necessary.

[0006] Second, the perovskite-based anode and the hydrogen anion solid electrolyte are solid materials with different crystal structures and different chemical environments. When the two come into direct contact, there are problems such as lattice mismatch, discontinuous chemical potential, local space charge layer and insufficient actual effective contact area, which leads to a high energy barrier for hydrogen anion migration across the interface.

[0007] Third, some perovskite oxides and hydrides have low electronic conductivity. When hydrogen ions rapidly reach the negative electrode interface through the solid electrolyte while electrons cannot reach the corresponding active sites in time, a mismatch between ion transport rate and electron transport rate occurs, leading to interfacial charge accumulation and electrode polarization. Although forming a dense carbon layer on the surface of perovskite particles can improve electronic conductivity, this dense electron-conducting layer can also obscure the hydrogen ion exchange interface, increasing the penetration distance of hydrogen ions and thus reducing ion transport efficiency.

[0008] Fourth, lithium doping alone can only adjust some lattice defects and cannot solve the problems of hydrogen ion exchange barrier and insufficient electron conduction at the solid electrolyte / anode interface. While introducing hydrogen ion exchange aids alone can reduce interfacial ion impedance, it cannot eliminate the irreversible trapping of hydrogen ions by deep defects within the perovskite, nor can it solve the electron transport bottleneck. Introducing conductive carbon materials alone can improve electron transport, but its improvement on deep hydrogen ion trapping and the hydrogen ion exchange barrier at the solid-solid interface is limited.

[0009] Therefore, there is an urgent need to construct a multifunctional interface structure that can synergistically regulate defect thermodynamics, hydrogen anion interface dynamics, and electron transport dynamics. Summary of the Invention

[0010] This invention provides a perovskite anode with a three-functional interface structure, aiming to solve the technical problems of irreversible deep trapping of hydrogen anions in perovskite-based anodes, high hydrogen anion exchange energy barrier at the interface between the anode and the solid electrolyte, and mismatch between electron transport rate and hydrogen anion transport rate.

[0011] Another object of the present invention is to provide a method for preparing the aforementioned three-functional interface perovskite anode.

[0012] Another object of the present invention is to provide a gas-solid hydrogen negative ion battery comprising the aforementioned three-functional interface perovskite negative electrode and its application.

[0013] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a perovskite anode with a three-functional interface structure, comprising: Perovskite-based anode active materials; A defect control layer is disposed on at least a portion of the surface of the perovskite-based anode active material, the defect control layer containing lithium element, for controlling the defect energy level distribution on the surface of the perovskite-based anode active material. An ion transport layer disposed on at least a portion of the surface of the defect control layer, the ion transport layer containing a hydrogen negative ion conductive material, is used to provide a hydrogen negative ion transport channel between the perovskite-based negative electrode active material and the solid electrolyte. An electron conduction layer is disposed on at least a portion of the surface of the ion transport layer and / or distributed in the gaps between adjacent perovskite particles. The electron conduction layer forms an electron conduction connection with at least one of the perovskite-based negative electrode active material, the defect control layer, and the ion transport layer to provide an electron transport pathway. The electron conduction layer has a window region for hydrogen negative ions to pass through.

[0014] Furthermore, in the defect control layer, lithium elements are distributed in the surface lattice of the perovskite-based anode active material in at least one manner selected from A-site substitution, B-site substitution, interstitial occupation, and defect adjacent enrichment.

[0015] Furthermore, the lithium content in the defect control layer is 0.1-15% of the total number of A-site and B-site elements in the perovskite-based anode active material, and the thickness of the defect control layer is 1-300 nm.

[0016] Furthermore, the lithium concentration in the defect control layer decreases from the surface of the perovskite-based anode active material particles to the interior, and the ratio of surface lithium atom content to interior lithium atom content is 1.2~20:1.

[0017] Furthermore, the material of the ion transport layer is at least one of metal hydride, metal oxyhydride and composite metal hydride, and the thickness of the ion transport layer is 2~1000 nm; the surface coverage of the ion transport layer on the defect control layer is 20~100%.

[0018] Furthermore, the material of the electron conduction layer is at least one of conductive carbon material, conductive ceramic material and conductive perovskite oxide, the thickness of the electron conduction layer is 1~500 nm, the surface coverage of the electron conduction layer to the ion transport layer is 10~95%, the area ratio of the window region is 5~90%, and the porosity of the electron conduction layer is 10~80%.

[0019] Furthermore, the three-functional interface structure can be any of the following configurations: The perovskite-based anode active material, defect regulation layer, ion transport layer and electron conduction layer are sequentially arranged in a multi-layer core-shell structure. The ion transport layer and electron conduction layer are interleaved and distributed on the surface of the defect control layer in an embedded structure. The structure consists of a double-sided partitioned structure with the ion transport layer located on the side facing the solid electrolyte and the electron conduction layer located on the side facing the current collector. The electron conduction layer forms a three-dimensional network in the gaps between adjacent perovskite particles, and the ion transport layer is located in a three-dimensional interpenetrating structure in the contact area between the particles and the solid electrolyte.

[0020] Furthermore, the perovskite-based anode active material has ABO content. 3- δ, ABO 3- δH x A n+1 B n O 3n+1- δH x and A2BB′H 6-x Any one of the chemical formulas shown, where 0 < δ < 1, 0 < x ≤ 6, and n is an integer from 1 to 4.

[0021] This invention provides a method for preparing the above-mentioned perovskite anode with a three-functional interface structure, comprising the following steps: S1. Provides perovskite-based anode active materials; S2. Introduce lithium elements on the surface of the perovskite-based anode active material to form a defect control layer; S3. An ion transport layer containing hydrogen negative ion conductive material is formed on the surface of the defect control layer. S4. An electron conduction layer with a window region is formed on the surface of the ion transport layer, in the gaps between adjacent perovskite particles, and / or on the side facing the current collector. S5. The composite material forming the three-functional interface structure is used to make the negative electrode layer.

[0022] The present invention also provides a gas-solid hydrogen negative ion battery, comprising a gaseous hydrogen positive electrode, a positive electrode gas diffusion / catalytic layer, a hydrogen negative ion solid electrolyte layer, the aforementioned perovskite negative electrode, a negative electrode current collector, and a battery casing.

[0023] Compared with the prior art, the present invention has at least the following beneficial effects: First, by selectively optimizing the near-surface defect energy levels of perovskite through a lithium-based defect control layer, rather than simply increasing the number of defects, the irreversible trapping ratio of hydrogen anions is effectively reduced, and the first-cycle coulombic efficiency is improved.

[0024] Second, by designing a gradient distribution of lithium concentration, the stability of the bulk lattice structure is maintained while enhancing the surface defect control effect.

[0025] Third, by establishing an ion conduction bridge between the perovskite-based negative electrode and the solid electrolyte through the ion transport layer, the cross-interface migration barrier and interfacial impedance of hydrogen negative ions are reduced.

[0026] Fourth, through the electron conduction layer with a window area, a continuous electron transport pathway is established while a hydrogen negative ion transport channel is retained, thus achieving a match between ion and electron transport rates.

[0027] Fifth, the three functional layers coordinate and regulate the three independent limiting steps of trapping, interface migration, and electronic transmission, resulting in a significant improvement in overall performance compared to single-functional-layer or dual-functional-layer structures.

[0028] Sixth, this invention is applicable to a variety of perovskite-based anode material systems and has good versatility. Attached Figure Description

[0029] Figure 1 for Figure 1 This is a schematic diagram of the overall structure of the three-functional interface perovskite anode of the present invention; Figure 2 This is a schematic diagram illustrating how the defect control layer regulates the distribution of deep and shallow defects. Figure 3 A schematic diagram illustrating how the ion transport layer lowers the migration barrier at the solid electrolyte / perovskite anode interface. Figure 4 A schematic diagram of an electron conduction layer structure with a window region; Figure 5 A schematic diagram of a multi-layered core-shell three-functional interface composite particle structure; Figure 6 A schematic diagram of a double-sided partitioned three-function interface negative electrode structure; Figure 7 A schematic diagram of a three-dimensional interpenetrating hydrogen anion channel and electron channel structure; Figure 8 This is a flowchart illustrating the preparation process of the three-functional interface perovskite anode of the present invention. Detailed Implementation

[0030] This invention provides a perovskite anode with a three-functional interface structure, comprising: Perovskite-based anode active materials; A defect control layer containing lithium is disposed on at least a portion of the surface of the perovskite-based anode active material. The defect control layer is used to control the defect energy level distribution on the surface of the perovskite-based anode active material. The lithium element occupies A-sites, B-sites, or interstitial sites in the perovskite surface lattice, thereby adjusting the local charge compensation mode and lattice strain state, and thus converting some deep defects with excessive binding energy for hydrogen anions into shallow reversible defects with moderate binding energy, thereby reducing the irreversible trapping ratio of hydrogen anions.

[0031] An ion transport layer is disposed on at least a portion of the surface of the defect control layer. The ion transport layer contains a hydrogen negative ion conducting material and is used to provide a hydrogen negative ion transport channel between the perovskite-based negative electrode active material and the solid electrolyte. As an intermediate medium layer, the ion transport layer can fill the microscopic voids at the solid-solid contact interface, increase the effective contact area, and transform the interface ion migration mode from a single high barrier crossing to a continuous low barrier transition by providing a hydrogen negative ion environment similar to the chemical potential of the materials on both sides.

[0032] An electron conduction layer is disposed on at least a portion of the surface of the ion transport layer and / or distributed in the gaps between adjacent perovskite particles. This electron conduction layer forms an electron conduction connection with at least one of the perovskite-based anode active material, the defect control layer, and the ion transport layer, providing an electron transport pathway. The electron conduction layer also has a window region for hydrogen anions to pass through. Through a porous structure, a discontinuous distribution structure, or a partitioned structure, the electron conduction layer establishes an electron conduction network throughout the anode while retaining sufficient channels for hydrogen anions to enter and exit, avoiding a significant mismatch between electron and ion transport rates.

[0033] In this invention, the defect control layer is not an independent lithium metal layer, but a defect control region formed after lithium enters the surface or near-surface region of the perovskite lattice. Lithium can regulate perovskite defects in the following ways: (1) by replacing high-valence or low-valence elements at A sites, causing charge compensation; (2) by replacing transition metals at B sites, regulating the valence state of the transition metals; (3) by occupying interstitial sites in the lattice; (4) by forming defect aggregates with oxygen vacancies, anion vacancies, or hydrogen vacancies; (5) by regulating the local electron density and defect energy levels on the surface; (6) by suppressing the clustering of excess oxygen vacancies; and (7) by reducing the strong coordination binding of transition metals to hydride anions.

[0034] In this invention, in the defect control layer, lithium elements are distributed in the surface lattice of the perovskite-based anode active material in at least one manner selected from A-site substitution, B-site substitution, interstitial occupation, and defect adjacent enrichment.

[0035] In this invention, the lithium content in the defect control layer is 0.1-15% of the total number of atoms of A-site and B-site elements in the perovskite-based anode active material, preferably 0.5-6%. When the lithium content is too low, the defect energy level regulation effect is limited; when the lithium content is too high, Li2O, LiOH, LiH or lithium-rich second phase may be formed, causing distortion of the perovskite framework. The thickness of the defect control layer is 1-300 nm, preferably 5-80 nm.

[0036] In this invention, the lithium concentration in the defect control layer decreases from the surface of the perovskite-based anode active material particles towards the interior. The ratio of surface lithium atom content to interior lithium atom content is 1.2~20:1, preferably 5~15:1. The higher lithium content on the particle surface is mainly used to control interface defects that directly participate in hydrogen anion exchange. The lower lithium content inside the particles is maintained to reduce the adverse effects of large-scale lithium substitution on the perovskite main crystal structure and bulk hydrogen storage sites.

[0037] In this invention, after the defect control layer is formed, it is treated at 150~700℃ for 0.5~20 h under hydrogen-containing atmosphere, inert atmosphere, low oxygen partial pressure atmosphere or vacuum conditions, so that lithium diffuses from the surface to the near-surface region, forming a lithium concentration gradient.

[0038] In this invention, the material of the ion transport layer is at least one of metal hydrides, metal oxyhydrides, and composite metal hydrides. The metal hydride is preferably at least one of BaH2, CeH3, LaH3, SrH2, and CaH2. The metal oxyhydride is preferably at least one of barium-based oxyhydride, lanthanum-based oxyhydride, and perovskite oxyhydride. The composite metal hydride is a core-shell composite hydride, an alkali metal composite hydride, or an alkaline earth metal composite hydride. The core-shell composite hydride is preferably 3CeH3@BaH2.

[0039] In this invention, the main functions of the ion transport layer include: (1) filling the micropores between the perovskite particles and the solid electrolyte; (2) increasing the actual solid-solid contact area; (3) reducing the chemical potential abrupt change when hydrogen negative ions directly enter the perovskite lattice from the solid electrolyte; (4) shortening the migration distance of hydrogen negative ions in the low ion conductivity region; and (5) forming multiple parallel hydrogen negative ion exchange channels.

[0040] In this invention, the thickness of the ion transport layer is 2~1000 nm, preferably 10~300 nm. Excessive thickness may increase ion migration distance and inactive mass, while insufficient thickness makes it difficult to form effective ion conduction bridging. The surface coverage of the ion transport layer over the defect control layer is 20~100%, preferably 50~95%. When the coverage is 100%, the ion transport layer is a continuous thin layer. When the coverage is less than 100%, the ion transport layer is an island-shaped distribution layer, a particle bridging layer, or a three-dimensional ion conduction network embedded in the gaps between adjacent perovskite particles.

[0041] In this invention, the material of the electron conduction layer is at least one of conductive carbon material, conductive ceramic material, and conductive perovskite oxide; the conductive carbon material is preferably at least one of conductive carbon black, Ketjen black, acetylene black, graphite, graphene, reduced graphene oxide, carbon nanotubes, carbon nanofibers, amorphous carbon, and porous carbon; the conductive ceramic material is preferably at least one of TiN, NbN, VN, TiC, Mo2C, and WC.

[0042] In this invention, in order to avoid the electron conduction layer blocking the hydrogen negative ion exchange interface, the electron conduction layer preferably adopts at least one of the following structures: (1) a porous carbon layer; (2) an island discontinuous carbon layer; (3) a carbon nanotube network layer; (4) a graphene sheet interlaced network; (5) a conductive ceramic particle point contact layer; (6) a gradient conductive layer enriched towards the current collector side; and (7) an interlaced layer with the ion transport layer.

[0043] In this invention, the thickness of the electron conduction layer is 1~500 nm, preferably 3~100 nm; the surface coverage of the electron conduction layer of the ion transport layer is 10~95%, preferably 20~80%, and retains a hydrogen negative ion transport window region with an area ratio of 5~90%; the porosity of the electron conduction layer is 10~80%, preferably 25~65%.

[0044] In this invention, the three-functional interface structure can be any one of the following configurations: (1) Multilayer core-shell configuration: from the inside out, the perovskite-based anode active material, the defect control layer, the ion transport layer, and the electron conduction layer are arranged sequentially; wherein, the electron conduction layer is a porous or discontinuous structure. This structure is suitable for particle-scale composite anodes.

[0045] (2) Two-sided partitioned configuration: The ion transport layer is disposed on the side of the negative electrode facing the solid electrolyte, and the electron conduction layer is disposed on the side of the negative electrode facing the current collector; the defect control layer and the ion transport layer are preferentially disposed on the side of the negative electrode facing the solid electrolyte, and the electron conduction layer is preferentially disposed on the side of the negative electrode facing the current collector. This structure can prevent the electron conduction layer from blocking the hydrogen negative ion exchange interface.

[0046] (3) Three-dimensional interpenetrating configuration: The defect control layer is disposed on the surface of the perovskite particles; the ion transport layer fills the contact area between the perovskite particles and the solid electrolyte; the electron conduction layer forms a three-dimensional network between the perovskite particles.

[0047] (4) Inlay configuration: The ion transport layer and the electron conduction layer are island-shaped or strip-shaped regions that are staggered on the surface of the defect control layer, forming hydrogen negative ion exchange region and electron contact region respectively.

[0048] In this invention, the perovskite-based anode active material has ABO content. 3- δ, ABO 3- δH x A n+1 B n O 3n+1- δH x and A2BB′H 6-x Any of the chemical formulas shown, where 0 < δ < 1, 0 < x ≤ 6, and n is an integer from 1 to 4; preferably, the perovskite-based anode active material is LaFeO. 3- δH x La 1-a Sr a FeO 3- δH x SrTiO 3- δH x BaTiO 3- δH x CaTiO 3- δH x LaTiO 3- δH x Sr2TiO 4- δH x Li2CaTiH 5-x Na2CaTiH 6-x Li2SrTiH 6-x and Li2BaTiH 6-x At least one of them.

[0049] In this invention, the perovskite anode further includes an anode current collector and a binder. The mass ratio of the perovskite-based anode active material, the hydrogen anion conducting material in the ion transport layer, the electron conducting material in the electron conducting layer, and the binder is 50~95:1~30:2~30:1~15. Preferably, it is 65~85:5~20:5~20:3~10.

[0050] This invention provides a method for preparing the above-mentioned perovskite anode with a three-functional interface structure, comprising the following steps: S1. Provides perovskite-based anode active materials; S2. Introduce lithium elements on the surface of the perovskite-based anode active material to form a defect control layer; S3. An ion transport layer containing hydrogen negative ion conductive material is formed on the surface of the defect control layer. S4. An electron conduction layer with a window region is formed on the surface of the ion transport layer, in the gaps between adjacent perovskite particles, and / or on the side facing the current collector. S5. The composite material forming the three-functional interface structure is used to make the negative electrode layer.

[0051] In this invention, in step S1, the perovskite-based anode active material can be prepared using a sol-gel method, co-precipitation method, hydrothermal method, spray pyrolysis method, solid-state reaction method, or mechanochemical method; for LaFeO 3- δH x SrTiO 3- δH x For perovskite hydrides, the corresponding perovskite oxides are first prepared, and then reversible hydride sites are formed through hydrogen treatment, hydrogen plasma treatment, metal hydride reduction, or electrochemical pre-intercalation treatment. For Li₂CaTiH₂... 5-x Double perovskite hydrides are prepared by high-energy ball milling and heat treatment under a protective atmosphere or a hydrogen atmosphere.

[0052] In this invention, in step S2, the perovskite-based negative electrode active material is contacted with a solution of a lithium-containing precursor, causing the lithium precursor to adsorb onto the particle surface. The lithium-containing precursor is at least one of LiNO3, LiOH, Li2CO3, lithium acetate, lithium citrate, and lithium ethoxide. After drying, it is heat-treated at 150-700°C under an inert atmosphere, a low-oxygen partial pressure atmosphere, a hydrogen-containing atmosphere, or a vacuum, causing lithium to diffuse from the surface to the near-surface region, forming a lithium concentration gradient. For hydride perovskite materials, low-temperature mechanochemical diffusion or solid-phase diffusion is performed using LiH, LiBH4, or other lithium-containing hydrides to avoid high-temperature oxidation.

[0053] When introducing lithium into the surface of the perovskite-based anode active material, at least one method selected from solution impregnation, sol-gel coating, molten salt diffusion, solid-phase diffusion, ion exchange, atomic layer deposition, chemical vapor deposition, magnetron sputtering, plasma-assisted diffusion, mechanochemical treatment, and electrochemical pre-intercalation treatment is used.

[0054] In this invention, in step S3, lithium-modified perovskite particles are dry-mechanically coated with an ion transport material. The ion transport material is at least one of BaH2, CeH3, 3CeH3@BaH2, or other hydride anion-conducting materials. The ion transport layer can also be formed through low-energy ball milling, melt wetting, cold pressing, atomic layer deposition, or in-situ reaction. To avoid damaging the defect-modifying layer, low temperature, low impact energy, and a protective atmosphere are preferred.

[0055] In this invention, in step S4, at least one of the following methods is used to form an electronic conductive layer with a window region: carbon source pyrolysis, chemical vapor deposition, spraying, dip coating, electrostatic spraying, conductive slurry coating, in-situ polymerization carbonization, and conductive ceramic deposition.

[0056] The composite particles forming the ion transport layer are contacted with a carbon source and then carbonized at low temperature in an inert atmosphere to form a porous carbon layer. The carbon source is at least one of glucose, sucrose, dopamine, and phenolic resin. Alternatively, carbon nanotubes, graphene, or conductive ceramic particles can be used for spraying, dip coating, or dry mixing. The electron conduction layer should be controlled to have a porous, discontinuous, or mesh structure to avoid forming a completely closed, dense outer shell.

[0057] In this invention, in step S5, the composite material forming the three-functional interface structure is mixed with a binder, and a negative electrode layer is formed by coating, scraping, dry pressing, screen printing, or composite lamination. In the double-sided partitioned structure, an ion transport enrichment layer is first formed on the side of the negative electrode close to the solid electrolyte, and then an electron conduction enrichment layer is formed on the side close to the current collector.

[0058] The present invention also provides a gas-solid hydrogen negative ion battery, comprising a gaseous hydrogen positive electrode, a positive electrode gas diffusion / catalytic layer, a hydrogen negative ion solid electrolyte layer, the aforementioned perovskite negative electrode, a negative electrode current collector, and a battery casing.

[0059] In the gas-solid hydrogen negative ion battery, the ion transport layer is located between the perovskite-based negative electrode active material and the solid electrolyte layer, and the electron conduction layer forms an electronic conduction connection with the perovskite-based negative electrode active material and the negative electrode current collector, respectively.

[0060] The mechanism of action of this invention is as follows: 1. Mechanism of Defect Control Layer The storage and release of hydride anions in perovskite-based anodes depend on oxygen vacancies, anion vacancies, interstitial sites, low-coordination metal sites, and other local defect sites. Different defect sites exhibit varying binding strengths to hydride anions: defect sites with moderate binding strength can accommodate hydride anions during discharge hydrogen storage and release them during charging hydrogen release; while defect sites with excessively high binding strength deeply trap hydride anions, making it difficult for them to escape from the lattice.

[0061] For shallow defect sites capable of reversible hydride ion storage, the reaction process can be represented as follows:

[0062] Where P represents the perovskite framework, s s This indicates a shallow defect site that can reversibly accommodate hydrogen anions, and PH indicates the state after the hydrogen anion occupies the defect site.

[0063] When defect clusters, severe lattice distortion, low-coordination transition metal centers, or regions with highly concentrated local electronic states exist on or near the surface of perovskite particles, deep defect traps with high binding energies for hydride anions may form. After entering these sites, the hydride anion's extraction process requires overcoming a high energy barrier, which can be represented as:

[0064] Where, d d Indicates a deep defect trap, PH trap This indicates the state of hydrogen negative ions that are bound by deep defects and difficult to completely release during charging.

[0065] This invention introduces lithium into the surface or near-surface region of a perovskite-based anode active material to form a defect control layer. Lithium exists in the perovskite near-surface lattice in at least one manner selected from A-site substitution, B-site substitution, interstitial occupancy, and defect ortho-enrichment, thereby regulating the local charge compensation mode, the degree of lattice distortion, the valence state of the B-site transition metal, and the defect energy level distribution.

[0066] When lithium enters the near-surface region of perovskite, its valence state, ionic radius, and coordination mode differ from those of the original A-site or B-site elements. Therefore, the perovskite lattice can achieve charge compensation by adjusting the oxygen vacancy concentration, anion vacancy distribution, B-site element valence state, and local electron density. This modulation process does not simply increase the total number of defects, but rather changes the type of defects, their spatial distribution, and their binding energy to hydrides. This transforms some deep defects with excessively strong hydride binding into shallow defect sites capable of reversible occupation and extraction. This transformation process can be represented as:

[0067] Subsequently, hydrogen anions can undergo reversible storage and release at lithium-regulated defect sites:

[0068] Among them, □ s (Li) represents a shallow defect reversible site formed by lithium regulation.

[0069] Lithium can also weaken the excessive electrostatic and coordination effects of low-coordination transition metal centers on hydride anions by adjusting the local electric field in the region near the defect. At the same time, the local lattice relaxation induced by lithium can reduce the structural rearrangement energy required for hydride anions to enter or leave the defect site, thereby reducing the hydride anion extraction barrier and improving the reversible utilization rate of the defect site.

[0070] 2. Mechanism of action of ion transport layer When a perovskite-based anode comes into direct contact with a hydride-containing solid electrolyte, the hydride ions need to cross an interface formed by different crystal structures and chemical environments. An ion transport layer forms an intermediate phase with a similar chemical environment for hydride ions between the two materials, transforming the hydride ion migration process from a single high-barrier transition to multiple consecutive low-barrier transitions. Simultaneously, the ion transport layer fills the solid-solid contact gaps, increasing the actual effective contact area and reducing localized current concentration.

[0071] 3. Mechanism of Electron Conductivity Layer When hydrogen ions enter or leave perovskite defect sites, electronic compensation must occur simultaneously. If the electron transport rate is lower than the hydrogen ion migration rate, charge accumulation and polarization will occur at the interface, preventing some hydrogen ion sites from being fully utilized. An electron-conducting layer forms a continuous electron network between perovskite particles, enabling electrons to quickly reach sites where hydrogen ion insertion or extraction occurs. By controlling the porosity and coverage of the electron-conducting layer, the hydrogen ion transport window can be preserved while improving electron conductivity.

[0072] 4. Three-layer synergistic mechanism The defect control layer addresses the question of whether hydrogen anions can reversibly escape after entering the perovskite; the ion transport layer addresses the question of whether hydrogen anions can efficiently cross the solid electrolyte / anode interface; and the electron conduction layer addresses the question of whether the electrons required for the hydrogen anion reaction can arrive synchronously. The three layers work together to synchronize the three processes of hydrogen anion migration across the interface, defect site occupancy, and electron compensation in terms of reaction kinetics.

[0073] 5. Summary of the collaborative relationships among the three functional layers In the three-functional interface perovskite anode of the present invention, each functional layer plays its own role in addressing different technical problems, and achieves a synergistic effect through mutual cooperation.

[0074] The main structural features of the defect control layer are lithium substitution, interstitial occupation, or surface gradient distribution, which are used to solve the problem of irreversible trapping of hydrogen anions by deep defects on the perovskite surface. Its mechanism of action lies in: by adjusting the defect formation energy, local valence state, and defect energy level distribution through lithium, some deep traps are transformed into shallow reversible sites. The direct technical effect of this functional layer is to improve the first-cycle efficiency and the reversible utilization rate of hydrogen anions.

[0075] The main structural feature of the ion transport layer is that it is a hydride conductor or a hydride bridging layer, which is used to address the high energy barrier for hydride ion exchange at the interface between perovskite and solid electrolyte. Its mechanism of action lies in establishing a continuous chemical potential for hydride ions and ion transport channels, thereby increasing the effective contact area. The direct technical effect of this functional layer is to reduce the hydride ion interface exchange impedance.

[0076] The main structural feature of the electron conduction layer is a porous, discontinuous, or three-dimensional conductive network, which is used to address the mismatch between electron transport and hydrogen ion transport rates. Its mechanism of action lies in constructing a continuous electron path from particle to particle to current collector while preserving the ion window. The direct technical effect of this functional layer is to reduce electron polarization and rate loss.

[0077] More importantly, the three functional layers mentioned above are not simply superimposed, but rather, through the coupling of ion transport, electronic conduction and defect regulation, the four processes of hydrogen anion entry, occupation, extraction and electronic compensation are matched on the time scale, thereby synergistically solving the three types of bottleneck problems that cannot be solved simultaneously by a single modification method, and ultimately achieving a comprehensive improvement in capacity, rate capability and cycling stability.

[0078] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0079] General testing and evaluation conditions: All examples and comparative examples used the same batch of LaFeO. 3- δH x Perovskite hydride is used as the basic negative electrode active material. The solid electrolyte uses the same batch of 3CeH3@BaH2 composite hydride. The positive electrode gas diffusion / catalytic layer uses the same loading of LaNi5 / porous nickel.

[0080] The effective area of ​​a single cell is 0.785 cm². 2 The test temperature was 25℃. The typical charge / discharge current density was 50 mA·g. -1 The initial reversible capacity test and cycle performance test were both conducted at this current density. In the rate performance test, the current densities were 50, 100, 150, and 200 mA·g. -1 The following tests were conducted sequentially. The hydrogen anion exchange impedance was obtained by electrochemical impedance spectroscopy and equivalent circuit fitting; the negative electrode electronic conductivity was measured by the four-probe method; the first-cycle coulombic efficiency was calculated as the ratio of the first-cycle reversible charge capacity to the first-cycle discharge capacity.

[0081] Example 1

[0082] This embodiment provides a three-functional interface perovskite anode with a multilayer core-shell structure.

[0083] LaFeO 3- δH x As a perovskite-based active core, LaFeO 3- δH xThe lithium acetate was dispersed in an ethanol solution to achieve an atomic ratio of lithium to the total amount of A-site and B-site elements in the perovskite of 2.5%. After drying, it was treated at 400℃ for 3 h in a 5% H2 / Ar atmosphere to form a defect control layer with a thickness of 20 nm.

[0084] The obtained powder was ball-milled with 3CeH3@BaH2 fine powder at a mass ratio of 85:15 to form an ion transport layer with a thickness of 50 nm.

[0085] Using glucose as a carbon source, a porous carbon electron conduction layer with a thickness of 10 nm and a coverage of 50% was formed by low-temperature carbonization at 550℃ in an inert atmosphere.

[0086] The resulting composite material is mixed with a binder and coated onto a current collector to form a negative electrode layer.

[0087] Testing showed that the first-cycle coulombic efficiency of the three-functional interface perovskite anode obtained in this embodiment was 86%; the hydrogen anion interface exchange resistance was 35 Ω·cm. 2 The electron conductivity at the negative electrode is 0.12 S·cm. -1 ;At 50 mA·g -1 The first reversible capacity is 380 mAh·g -1 ;At 50 mA·g -1 The capacity retention rate after the next 100 cycles is 90%.

[0088] Example 2

[0089] This embodiment provides a three-functional interface perovskite anode with a lithium concentration gradient defect layer and a graphene-carbon nanotube composite electronic conduction network.

[0090] LaFeO 3- δH x As the active core, the lithium content on the particle surface is 4 at%, and the lithium content inside the particle is 0.8 at%, which is achieved by two low-concentration lithium acetate impregnations and one low-temperature diffusion treatment, forming a lithium concentration gradient that gradually decreases from the surface to the inside.

[0091] An ion transport layer with a thickness of 80 nm was formed using CeH3@BaH2 composite particles.

[0092] A graphene-carbon nanotube composite network was constructed on the outside of the ion transport layer, with an electron conduction layer coverage of 45% and an open porosity of 50%.

[0093] Testing showed that the first-cycle coulombic efficiency of the three-functional interface perovskite anode obtained in this embodiment was 89%; the hydrogen anion interface exchange resistance was 24 Ω·cm. 2 The electron conductivity of the negative electrode is 0.26 S·cm. -1;At 50 mA·g -1 The first reversible capacity is 400 mAh·g -1 ;At 50 mA·g -1 The capacity retention rate after the next 100 cycles was 92%; at 50 mA·g -1 The capacity retention rate after the next 200 cycles is 86%.

[0094] Example 3

[0095] This embodiment provides a three-functional interface perovskite anode with a double-sided partitioned structure.

[0096] Lithium-modified LaFeO 3- δH x As the main anode, a 3CeH3@BaH2 enrichment layer is formed on the side of the anode facing the solid electrolyte, with the ion transport material accounting for 25% of the mass on this side. A carbon nanotube and graphene enrichment layer is formed on the side of the anode facing the current collector, with the conductive material accounting for 20% of the mass on this side. The hydrogen storage region, mainly composed of lithium-regulated perovskite particles, is retained in the middle of the anode.

[0097] Testing showed that the first-cycle coulombic efficiency of the three-functional interface perovskite anode obtained in this embodiment was 88%; the hydrogen anion interface exchange resistance was 28 Ω·cm. 2 The in-plane electron conductivity is 0.30 S·cm. -1 ;At 200 mA·g -1 The reversible capacity is at 50 mA·g -1 78% of the capacity; at 50 mA·g -1 The capacity retention rate after the next 100 cycles is 92%.

[0098] Example 4

[0099] This embodiment provides a method using Li2CaTiH 6-x A three-functional interface perovskite anode with a double perovskite hydride as the active core.

[0100] Using Li2CaTiH 6-x As the active core, a lithium-enriched defect layer with a lithium content of 5 at% and a lithium content of 1.5 at% inside the particle is formed on the particle surface through low-energy mechanochemical treatment.

[0101] An ion transport layer is formed using a BaH2-CeH3 composite hydride.

[0102] A porous electron conduction layer is formed using TiN nanoparticles and carbon nanotubes.

[0103] Testing showed that the first-cycle coulombic efficiency of the three-functional interface perovskite anode obtained in this embodiment was 84%; the hydrogen anion interface exchange resistance was 30 Ω·cm. 2 The negative electrode electron conductivity is 0.10 S·cm. -1 ;At 50 mA·g -1 The first reversible capacity is 510 mAh·g -1 ;At 50 mA·g -1 The capacity retention rate after the next 100 cycles is 87%.

[0104] Example 5

[0105] This embodiment provides a three-dimensional interpenetrating perovskite anode with a three-dimensional interpenetrating structure and three functional interfaces.

[0106] Using lithium-controlled LaFeO 3- δH x A 300 μm thick negative electrode layer was prepared using particles. Fine 3CeH3@BaH2 particles were dispersed in the gaps between adjacent perovskite particles, preferentially enriching on the side closer to the solid electrolyte, forming a three-dimensional hydrogen anion conduction network. Carbon nanotubes and Ketjen black formed an electron conduction network penetrating the thickness direction of the negative electrode between the particles.

[0107] Testing showed that the utilization rate of the active material in the thick negative electrode obtained in this embodiment was 82%; the hydrogen anion interface exchange resistance was 35 Ω·cm. 2 The electron conductivity along the thickness direction of the negative electrode is 0.18 S·cm. -1 ;At 50 mA·g -1 The capacity retention rate after the next 100 cycles is 90%.

[0108] Example 6

[0109] This embodiment provides a three-functional interface perovskite anode with an embedded interface structure.

[0110] Island-shaped BaH2 particles and graphene sheets are alternately deposited on the surface of the defect control layer. The BaH2 island regions account for 50% of the surface area and serve as hydrogen ion exchange regions; the graphene and carbon nanotube regions account for 30% of the surface area and serve as electron contact regions; the remaining 20% ​​of the area forms interconnected hydrogen ion transport windows.

[0111] Testing showed that the first-cycle coulombic efficiency of the three-functional interface perovskite anode obtained in this embodiment was 88%; the hydrogen anion interface exchange resistance was 26 Ω·cm. 2 The electron conductivity of the negative electrode is 0.23 S·cm. -1 ;At 50 mA·g -1 The capacity retention rate after the next 100 cycles is 91%.

[0112] The main performance parameters of each embodiment are shown in Table 1.

[0113] Table 1 Summary of Performance of Examples

[0114] Comparative Example 1 LaFeO without lithium regulation, without an ion transport layer, and without a dedicated electron conduction layer was used. 3- δH x negative electrode.

[0115] The initial coulombic efficiency was 62%; the hydrogen anion interfacial exchange impedance was 115 Ω·cm. 2 The electron conductivity of the negative electrode is 0.006 S·cm. -1 The initial reversible capacity is 310 mAh·g. -1 The capacity retention rate after 100 cycles was 64%.

[0116] Comparative Example 2 The same lithium modulation treatment as in Example 1 was used, but without the ion transport layer and electron conduction layer.

[0117] Tests showed that the coulombic efficiency for the first cycle was 75%; the interfacial exchange resistance of hydrogen anions was 95 Ω·cm. 2 The electronic conductivity is 0.008 S·cm. -1 The capacity retention rate after 100 cycles was 74%.

[0118] Comparative Example 3 Without lithium regulation, in ordinary LaFeO 3- δH x A 3CeH3@BaH2 ion transport layer is formed on the surface.

[0119] The measured interfacial exchange impedance of hydrogen anions is 46 Ω·cm. 2 The first-cycle coulomb efficiency is 68%; the electronic conductivity is 0.010 S·cm. -1 The capacity retention rate after 100 cycles was 77%.

[0120] Comparative Example 4 Without lithium regulation or the establishment of an ion transport layer, only in LaFeO 3- δH x A porous carbon layer is formed on the surface.

[0121] The electronic conductivity was measured to be 0.15 S·cm. -1 The interfacial exchange impedance of hydrogen anions is 100 Ω·cm. 2 The first-cycle coulomb efficiency was 66%; the capacity retention rate after 100 cycles was 76%.

[0122] Comparative Example 5 A defect control layer and an ion transport layer are provided, but a continuous electron conduction network is not provided.

[0123] The initial coulombic efficiency was 82%; the hydrogen anion interfacial exchange impedance was 32 Ω·cm. 2 The electronic conductivity is 0.012 S·cm. -1 The capacity retention rate after 100 cycles was 84%.

[0124] Comparative Example 6 Instead of lithium regulation, an ion transport layer and a porous electron conduction layer are constructed.

[0125] The hydrogen ion exchange impedance was measured to be 34 Ω·cm. 2 The electronic conductivity is 0.18 S·cm. -1 The first-cycle coulomb efficiency was 70%; the capacity retention rate after 100 cycles was 82%.

[0126] Comparative Example 7 The same defect control layer and ion transport layer as in Example 1 are used, but a continuous dense carbon shell is formed on the outside, with an electron conduction layer coverage of 98% and a porosity of 3%.

[0127] The electronic conductivity was measured to be 0.30 S·cm. -1 The interfacial exchange impedance of hydrogen anions is 80 Ω·cm. 2 The first reversible capacity is 330 mAh·g. -1 The capacity retention rate after 100 cycles was 76%.

[0128] Comparative Example 8 The lithium content was increased to 12 at%, and the rest of the structure was the same as in Example 1.

[0129] Testing revealed the presence of a lithium-rich second phase and lattice distortion in the sample; the first-cycle coulombic efficiency was 73%; and the hydrogen anion exchange impedance was 52 Ω·cm. 2 The capacity retention rate after 100 cycles was 77%.

[0130] Table 2 shows a comparison of the key performance characteristics of Example 2 and the comparative example.

[0131] Table 2 Comparison of key performance characteristics between Example 2 and the comparative example

[0132] As shown in Tables 1 and 2, compared with the comparative examples having only a single functional layer or a dual functional layer, the three-functional interface structure of the present invention can simultaneously improve the first-cycle coulombic efficiency, hydride anion interface exchange impedance, and electronic conductivity, significantly improving capacity retention and cycle stability. Comparative Examples 7 and 8 further demonstrate that the porosity and lithium content of the electronic conduction layer need to be controlled within appropriate ranges; excessive or insufficient content will adversely affect battery performance.

[0133] The three-functional interface perovskite anode and its preparation method provided by this invention have good process compatibility and can be applied to different types of perovskite oxide, oxyhydride, and double perovskite hydride anode systems. Gas-solid hydrogen negative ion batteries incorporating this anode can effectively reduce irreversible capacity loss, interfacial impedance, and electrode polarization, exhibiting excellent rate performance and cycle stability. This invention can be widely applied in hydrogen-electricity co-storage systems, low-pressure hydrogen storage systems, fuel cell hydrogen supply systems, stationary energy storage systems, mobile energy systems, unmanned equipment power supplies, and emergency power supply systems, possessing significant industrial practical value and broad market application prospects.

[0134] 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. A perovskite anode with a three-functional interface structure, characterized in that, include: Perovskite-based anode active materials; A defect control layer is disposed on at least a portion of the surface of the perovskite-based anode active material, the defect control layer containing lithium element, for controlling the defect energy level distribution on the surface of the perovskite-based anode active material. An ion transport layer disposed on at least a portion of the surface of the defect control layer, the ion transport layer containing a hydrogen negative ion conductive material, is used to provide a hydrogen negative ion transport channel between the perovskite-based negative electrode active material and the solid electrolyte. An electron conduction layer is disposed on at least a portion of the surface of the ion transport layer and / or distributed in the gaps between adjacent perovskite particles. The electron conduction layer forms an electron conduction connection with at least one of the perovskite-based negative electrode active material, the defect control layer, and the ion transport layer to provide an electron transport pathway. The electron conduction layer has a window region for hydrogen negative ions to pass through.

2. The perovskite anode with a three-functional interface structure according to claim 1, characterized in that, In the defect control layer, lithium elements are distributed in the surface lattice of the perovskite-based anode active material in at least one manner selected from A-site substitution, B-site substitution, interstitial occupation, and defect adjacent enrichment.

3. The perovskite anode with a three-functional interface structure according to claim 2, characterized in that, The lithium content in the defect control layer is 0.1-15% of the total number of A-site and B-site elements in the perovskite-based anode active material, and the thickness of the defect control layer is 1-300 nm.

4. The perovskite anode with a three-functional interface structure according to any one of claims 1 to 3, characterized in that, The concentration of lithium in the defect control layer decreases from the surface of the perovskite-based anode active material particles to the interior, and the ratio of surface lithium atom content to interior lithium atom content is 1.2~20:

1.

5. The perovskite anode with a three-functional interface structure according to claim 4, characterized in that, The material of the ion transport layer is at least one of metal hydride, metal oxy hydride and composite metal hydride, and the thickness of the ion transport layer is 2~1000 nm; the surface coverage of the ion transport layer on the defect control layer is 20~100%.

6. The perovskite anode with a three-functional interface structure according to claim 5, characterized in that, The electron conduction layer is made of at least one of conductive carbon material, conductive ceramic material, and conductive perovskite oxide, and the thickness of the electron conduction layer is 1~500 nm; the surface coverage of the electron conduction layer to the ion transport layer is 10~95%, the area ratio of the window region is 5~90%, and the porosity of the electron conduction layer is 10~80%.

7. The perovskite anode with a three-functional interface structure according to claim 1, characterized in that, The three-functional interface structure can be any of the following configurations: The perovskite-based anode active material, defect regulation layer, ion transport layer and electron conduction layer are sequentially arranged in a multi-layer core-shell structure. The ion transport layer and electron conduction layer are interleaved and distributed on the surface of the defect control layer in an embedded structure. The structure consists of a double-sided partitioned structure with the ion transport layer located on the side facing the solid electrolyte and the electron conduction layer located on the side facing the current collector. The electron conduction layer forms a three-dimensional network in the gaps between adjacent perovskite particles, and the ion transport layer is located in a three-dimensional interpenetrating structure in the contact area between the particles and the solid electrolyte.

8. The perovskite anode with a three-functional interface structure according to claim 7, characterized in that, The perovskite-based negative electrode active material has ABO 3- δ, ABO 3- δH x , A n+1 B n O3 n+1- δH x and A2BB' H 6-x Any one of the chemical formulas shown in the formula, wherein 0 < δ < 1, 0 < x ≤ 6, n is an integer of 1~4.

9. A method for preparing a perovskite anode with a three-functional interface structure as described in any one of claims 1 to 8, characterized in that, Includes the following steps: S1. Provides perovskite-based anode active materials; S2. Introduce lithium elements on the surface of the perovskite-based anode active material to form a defect control layer; S3. An ion transport layer containing hydrogen negative ion conductive material is formed on the surface of the defect control layer. S4. An electron conduction layer with a window region is formed on the surface of the ion transport layer, in the gaps between adjacent perovskite particles, and / or on the side facing the current collector. S5. The composite material forming the three-functional interface structure is used to make the negative electrode layer.

10. A gas-solid hydrogen negative ion battery, characterized in that, It includes a gaseous hydrogen positive electrode, a positive electrode gas diffusion / catalytic layer, a hydrogen negative ion solid electrolyte layer, a perovskite negative electrode according to any one of claims 1 to 8, a negative electrode current collector, and a battery casing.

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