Solid-state battery cell structure, solid-state battery, battery manufacturing apparatus, and battery manufacturing process

Abstract

The application belongs to the technical field of solid-state batteries, and particularly relates to a battery cell structure of a solid-state battery, the solid-state battery, a battery manufacturing device and a battery manufacturing process. The battery cell structure comprises a positive electrode sheet, a solid-state electrolyte layer and a negative electrode sheet arranged in sequence. The solid-state electrolyte layer has a wave-shaped structure, and the two side surfaces of the solid-state electrolyte layer are both provided with a micro-nano level convex point array. The surface of the convex point is provided with a self-repairing dynamic interface layer. The side of the positive electrode sheet facing the solid-state electrolyte layer is provided with a first wave-shaped surface, and the first wave-shaped surface has a gradient pore structure. The negative electrode sheet is provided with a second wave-shaped surface, and the second wave-shaped surface has a gradient pore structure. The self-repairing dynamic interface layer can autonomously repair micro-cracks generated in cycles, and cooperates with the mechanical anchoring of the convex point array to solve the problem of impedance rise caused by interface cracks in traditional solid-state batteries, and significantly prolongs the cycle life.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of solid-state batteries, and particularly relates to a solid-state battery cell structure, a solid-state battery, a battery manufacturing device and a battery manufacturing process. BACKGROUND

[0002] Solid-state batteries, also known as all-solid-state lithium batteries, are energy storage devices that do not contain liquid in their structure, with all materials existing in solid form. Specifically, they are composed of positive electrode material + negative electrode material and electrolyte, while liquid lithium batteries are composed of positive electrode material + negative electrode material + electrolyte and separator. Solid-state batteries use non-flammable solid-state battery electrolyte to replace flammable organic liquid electrolyte, greatly improving the safety of the battery system, while better adapting to high-energy positive and negative electrodes and reducing system weight, achieving synchronous improvement of energy density. Among various new battery systems, solid-state batteries are the closest next-generation technology to industrialization, which has become a consensus in the industry and scientific community.

[0003] Chinese Patent No. 202311807870.5 discloses a solid-state battery cell structure

[0004] comprising a positive electrode sheet, a solid-state electrolyte layer and a negative electrode sheet arranged in sequence, the two sides of the solid-state electrolyte layer are coupled with the positive electrode sheet and the negative electrode sheet respectively, and the solid-state electrolyte layer has a wave-shaped structure. It can solve the problem of low production efficiency and thick electrode thickness affecting ion transmission in traditional solid-state batteries with layer-by-layer stacked structure. It also discloses a solid-state battery comprising a solid-state battery cell structure, at least two of the cell structures are stacked, and a positive current collector is arranged outside the positive electrode sheet after stacking, and a negative current collector is arranged outside the negative electrode sheet. It can solve the problem of large weight and low energy density of solid-state batteries.

[0005] In the existing solid-state batteries, the thermal expansion characteristics of the electrode material and the solid-state electrolyte differ significantly. During the charging and discharging cycles and temperature changes, periodic thermal stress is easily generated at the interface, leading to the generation and expansion of micro-cracks, and ultimately causing interface peeling, which seriously affects the cycle life and stability of the battery. In the traditional structure, the contact area between the current collector and the electrode layer is limited, the contact resistance is high, and the resistance accumulation effect is obvious when stacked in multiple layers, resulting in a decrease in battery power performance. At the same time, there is a lack of targeted thermal management design, and local heat is accumulated during high-rate charging and discharging, which may cause material performance degradation and safety hazards. SUMMARY

[0006] In view of the above deficiencies in the prior art, the present application provides a solid-state battery cell structure, a solid-state battery, a battery manufacturing device and a battery manufacturing process to solve the problems in the background art.

[0007] To solve the above technical problems, the present application adopts the following technical solutions:

[0008] In a first aspect, the present application provides a solid-state battery cell structure, comprising a positive electrode sheet, a solid-state electrolyte layer and a negative electrode sheet arranged in sequence; the solid-state electrolyte layer has a wave structure, both sides of the solid-state electrolyte layer are provided with a micro-nano level bump array, and the surface of the bump is provided with a self-repairing dynamic interface layer;

[0009] The side of the positive electrode sheet facing the solid-state electrolyte layer is provided with a first wave surface matching the wave structure on one side of the solid-state electrolyte layer, and the first wave surface has a gradient pore structure; the side of the negative electrode sheet facing the solid-state electrolyte layer is provided with a second wave surface matching the wave structure on the other side of the solid-state electrolyte layer, and the second wave surface has a gradient pore structure;

[0010] Both sides of the solid-state electrolyte layer are coupled with the first wave surface of the positive electrode sheet and the second wave surface of the negative electrode sheet through the micro-nano level bump array and the self-repairing dynamic interface layer.

[0011] Further, the bumps of the micro-nano level bump array are conical or circular truncated cone shaped, the bump height is 1-5 μm, the bottom diameter is 5-20 μm, and the distance between adjacent bumps is 20-50 μm.

[0012] Further, the self-repairing dynamic interface layer is a polymer layer containing reversible dynamic covalent bonds, and the thickness of the self-repairing dynamic interface layer is 50-200 nm.

[0013] Further, the wave structure of the solid-state electrolyte layer is one of a sine wave structure, a square wave structure or a triangular wave structure.

[0014] Further, the pores in the gradient pore structure present a continuous and gradual distribution from the interface side close to the solid-state electrolyte layer to the current collector side away from the solid-state electrolyte layer, the number of pores gradually decreases away from the solid-state electrolyte layer, and the overall density of the pores decreases in a stepwise manner from the interface side to the current collector side.

[0015] Further, the total thickness of the solid-state electrolyte layer is 10-100 μm, the thickness of the positive electrode sheet is 20-300 μm, and the thickness of the negative electrode sheet is 10-200 μm.

[0016] Further, the side of the positive electrode sheet away from the solid-state electrolyte layer is provided with a first conductive transition layer, and the first conductive transition layer is a composite layer of conductive carbon nanotubes and graphene with a thickness of 1-5 μm.

[0017] Furthermore, a second conductive transition layer is provided on the side of the negative electrode sheet away from the solid electrolyte layer. The second conductive transition layer is a composite layer of conductive carbon black and carbon fiber with a thickness of 1-5 μm.

[0018] Secondly, the present invention also provides a solid-state battery, comprising at least two of the above-mentioned cell structures, wherein the cell structures are stacked sequentially, and a positive current collector is disposed outside the first conductive transition layer of the outermost positive electrode sheet after stacking, and a negative current collector is disposed outside the second conductive transition layer of the outermost negative electrode sheet, wherein the positive current collector is press-fitted to the first conductive transition layer, and the negative current collector is press-fitted to the second conductive transition layer.

[0019] Thirdly, the present invention also provides a battery manufacturing apparatus, including a mold opening and closing unit for opening or closing an injection mold, wherein the inner wall of the injection mold cavity is provided with a micro-nano pit array that matches the micro-nano-level bump array, and the mold cavity is used to form the core of the solid electrolyte layer of the above-mentioned cell structure.

[0020] An atomic layer deposition unit is used to deposit a shell on the surface of the solid electrolyte layer core, the atomic layer deposition unit comprising a precursor supply device and a vacuum reaction chamber;

[0021] A pressing unit is used to press the positive electrode sheet, the solid electrolyte layer and the negative electrode sheet together. The pressing head surface of the pressing unit is provided with a waveform structure that matches the first waveform surface and the second waveform surface.

[0022] A coating unit is used to coat the surface of the micro-nano-scale bump array with a self-healing dynamic interface layer material, and the coating unit is manufactured using an aerosol jet printing device.

[0023] Fourthly, the present invention also provides a battery manufacturing process for forming the above-mentioned solid-state battery cell structure, comprising the following steps:

[0024] S1: Preparation of solid electrolyte layer: Molten electrolyte is injected into the mold cavity of injection mold, cooled and demolded to obtain a solid electrolyte layer with waveform structure and micro-nano-scale bump array;

[0025] S2: Preparation of positive electrode sheet: Prepare positive electrode slurry, inject the positive electrode slurry into a mold with a first wave surface, form a first wave surface with a gradient pore structure through gradient sintering process, bake and roll and demold, and coat a first conductive transition layer on the side away from the first wave surface.

[0026] S3: Preparation of negative electrode sheet: Prepare negative electrode slurry, inject the negative electrode slurry into a mold with a second wave surface, form a second wave surface with a gradient pore structure through gradient sintering process, bake and roll and demold, and coat a second conductive transition layer on the side away from the second wave surface.

[0027] S4: sequentially align the first wavy surface of the positive electrode sheet, one side of the solid-state electrolyte layer, and the second wavy surface of the negative electrode sheet, and press and form a half battery through a pressing unit;

[0028] S5: stack at least two half batteries, press the positive current collector through the first conductive transition layer of the outermost positive electrode sheet, and press the negative current collector through the second conductive transition layer of the outermost negative electrode sheet to form a battery cell;

[0029] S6: baking the battery cell at a temperature of 80-120℃ for 2-4h.

[0030] Further, the gradient sintering process in steps S2 and S3 is: pre-sintering at 30-60℃ for 1-2h, then heating to 100-150℃ at a rate of 5-10℃ / min, and keeping for 2-3h.

[0031] Compared with the prior art, the present application has the following beneficial effects:

[0032] 1. Through the four-way synergistic design of "wavy adaptation + convex point anchoring + self-repairing protection + gradient buffering", the core problems of insufficient interface contact, poor stability and stress damage of solid-state batteries are solved, wherein the repair dynamic interface layer can autonomously repair the micro-cracks generated in the cycle, and cooperates with the mechanical anchoring of the convex point array to solve the problem of impedance rise caused by interface cracks in traditional solid-state batteries, and significantly prolongs the cycle life;

[0033] 2. The wavy structure + micro-nano convex point array greatly increases the interface contact area, the gradient pore structure optimizes the wettability of the electrolyte to the electrode, shortens the ion transmission path, reduces the interface impedance, and improves the battery charge and discharge efficiency;

[0034] 3. The wavy adaptation design cooperates with the gradient pore structure to buffer the expansion and contraction difference of the electrode and the electrolyte, reduces the stress concentration in the cycle process, reduces the risk of interface peeling, and improves the stability of the battery structure;

[0035] 4. The gradient pore structure enhances the contact and buffering near the electrolyte side through high porosity, and ensures the strength of the electrode through low porosity away from the side, and the self-repairing layer gives the interface the ability of "damage self-healing" without sacrificing ion conduction, realizing the synergistic optimization of multiple performance indicators. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 It is a structural schematic diagram of the battery cell structure of the solid-state battery of the present application;

[0037] Figure 2 It is a schematic diagram of the solid-state electrolyte layer in the battery cell structure of the solid-state battery of the present application;

[0038] Figure 3 Fig. 1 is a schematic diagram of a solid-state battery according to the present application; Figure 2 Fig. 2 is a local enlarged view at A in Fig. 1;

[0039] Figure 4 Fig. 3 is a schematic diagram of a positive electrode sheet in a cell structure of a solid-state battery according to the present application;

[0040] Figure 5 Fig. 4 is a schematic diagram of a negative electrode sheet in a cell structure of a solid-state battery according to the present application;

[0041] Figure 6 Fig. 5 is a schematic diagram of a battery manufacturing device according to the present application;

[0042] Figure 7 Fig. 6 is a flow chart of a battery manufacturing process according to the present application;

[0043] The reference signs in the drawings of the specification include:

[0044] 1, solid-state electrolyte layer; 101, bump; 102, self-repairing dynamic interface layer; 2, positive electrode sheet; 201, first conductive transition layer; 202, positive current collector; 203, pore; 3, negative electrode sheet; 301, second conductive transition layer; 302, negative current collector. DETAILED DESCRIPTION

[0045] In order for those skilled in the art to better understand the present application, the technical solutions of the present application are further described below in conjunction with the drawings and examples.

[0046] Among them, the drawings are only used for exemplary illustration, and the representation is only a schematic diagram, not a physical diagram, and cannot be understood as a limitation on the present patent; in order to better illustrate the embodiments of the present application, some components of the drawings will be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings can be omitted.

[0047] Based on the significant difference in thermal expansion characteristics between the electrode material and the solid-state electrolyte in the existing solid-state battery, during the charge and discharge cycle and the temperature change process, periodic thermal stress is easily generated at the interface, leading to the generation and expansion of micro-cracks, and ultimately triggering the interface peeling, which seriously affects the cycle life and stability of the battery. In the traditional structure, the contact area between the current collector and the electrode layer is limited, the contact resistance is high, and the resistance accumulation effect is obvious when stacked in multiple layers, leading to the decline of the battery power performance; at the same time, there is a lack of targeted thermal management design, and local heat is accumulated during high-rate charging and discharging, which exists the risk of material performance degradation and safety hazard.

[0048] The application provides a solid-state battery cell structure, comprising a positive electrode sheet, a solid-state electrolyte layer and a negative electrode sheet arranged in sequence; the solid-state electrolyte layer has a wave structure, both sides of the solid-state electrolyte layer are provided with a micro-nano level protrusion array, and the surface of the protrusion is provided with a self-repairing dynamic interface layer; the side of the positive electrode sheet facing the solid-state electrolyte layer is provided with a first wave surface matching the wave structure on one side of the solid-state electrolyte layer, and the first wave surface has a gradient pore structure; the side of the negative electrode sheet facing the solid-state electrolyte layer is provided with a second wave surface matching the wave structure on the other side of the solid-state electrolyte layer, and the second wave surface has a gradient pore structure; the two sides of the solid-state electrolyte layer are coupled with the first wave surface of the positive electrode sheet and the second wave surface of the negative electrode sheet through the micro-nano level protrusion array and the self-repairing dynamic interface layer.

[0049] The wave structure significantly increases the contact area of the electrolyte and the electrode compared with a planar structure, and the micro-nano level protrusion array is embedded in the gradient pores of the electrode to form a "physical anchoring" effect, that is, the protrusions penetrate into the pores and the pores fill the gaps between the protrusions, which greatly improves the actual contact area of the interface, shortens the ion transmission path and reduces the interface impedance. The self-repairing dynamic interface layer on the surface of the protrusion acts as an "active buffer layer", and when micro-cracks are generated between the electrode and the electrolyte due to expansion and contraction during the charging and discharging cycle of the battery, the cracks can be self-healed through the reversible chemical / physical action (such as dynamic covalent bond reorganization) of the material itself, the interface integrity is maintained, and the impedance is prevented from rising due to crack propagation. The gradient pore structure of the wave surface of the electrode gradually changes from the side close to the electrolyte to the side away from the electrolyte, which not only provides sufficient embedding space for the electrolyte protrusions (the high-porosity side enhances the wettability), but also gradually improves the structural strength of the electrode by reducing the porosity (the low-porosity side ensures the mechanical stability); at the same time, the wave structure and the gradient pore structure can buffer the thermal stress and mechanical stress in the cycle process, reduce the risk of interface peeling. The gradient pore structure optimizes the wettability of the electrolyte to the electrode, shortens the ion transmission path, reduces the interface impedance, improves the charging and discharging efficiency of the battery, the wave matching design and the gradient pore structure cooperatively buffer the expansion and contraction difference between the electrode and the electrolyte, reduce the stress concentration in the cycle process, reduce the risk of interface peeling, improve the structural stability of the battery, the gradient pore structure provides contact and buffering on the side close to the electrolyte through high porosity, and ensures the strength of the electrode on the side away from the electrolyte through low porosity, and the self-repairing layer endows the interface with the ability of "damage self-healing" without sacrificing ion conduction, realizing the synergistic optimization of multiple performance indicators.

[0050] In some embodiments, the protrusions of the micro-nano level protrusion array are conical or frustoconical, the height of the protrusions is 1-5 μm, the diameter of the base surface is 5-20 μm, and the distance between adjacent protrusions is 20-50 μm.

[0051] In the charge-discharge cycle of solid-state batteries, the electrode and electrolyte will expand and shrink due to the difference in material properties. The bump structure can be directly embedded in the gradient pores of the electrode, forming a physical anchoring structure similar to "mortise and tenon engagement". The bumps of the electrolyte layer penetrate the pore area of the electrode, and the electrode material fills the gap between the bumps, so that the interface forms a mechanically locked relationship of mutual embedding. This structure can effectively resist the peeling force in the cycle process, reduce the interface micro-cracks caused by stress, and significantly improve the interface stability. The bump design can increase the effective contact area of the electrolyte and the electrode through "three-dimensional extension". Based on the wave structure, the bumps protrude towards the electrode, converting the original planar or simple wave contact into a three-dimensional contact of "wave + bump". The larger contact area can shorten the ion transmission path and reduce the interface impedance, which is crucial for solid-state batteries that rely on interface contact for ion conduction. The solid-state electrolyte layer is prepared by injection molding process. The micro-nano pit array on the inner wall of the mold cavity can directly copy the bump structure (mold pit → electrolyte bump). This process is mature and easy to control in precision (the height and spacing of micro-nano bumps can be accurately set by the mold). The bump structure is more likely to be formed during the cooling and solidification process of the molten electrolyte, and the connection strength between the root of the bump and the main body of the electrolyte layer is higher, and it is not easy to fall off in subsequent processing.

[0052] In addition, it is explained why bumps are designed on the surface of the solid-state electrolyte layer instead of pits. First, in the pit design, the contact between the electrolyte and the electrode mainly depends on the edge of the pit, and the inside of the pit will form a "cavity area" that cannot participate in ion transmission, leading to an increase in interface impedance. Second, the pit structure cannot form an effective mechanical anchor. If the electrode material is to match the pit, it needs to form a bump itself, but the electrode active material (such as ternary material, graphite) is usually high in brittleness, and micro-nano bumps are easy to break in compression or cycle; even if the electrode remains flat, the edge of the pit will become a stress concentration area and is easy to crack in the cycle, leading to interface peeling. The pit structure is easy to leave bubbles or impurities during the compression process, forming a "dead zone" for ion transmission; at the same time, the increased thickness of the electrolyte at the bottom of the pit will lengthen the ion transmission path and reduce the conduction efficiency. Third, pits need to be processed into a concave structure on the surface of the electrolyte layer. The formation of micro-nano pits is prone to edge burrs, uneven depth, etc.; and the material thickness at the bottom of the pit is thin, and cracks are easy to occur due to uneven stress during cooling and solidification, reducing the structural integrity of the electrolyte layer, and the manufacturing process is more difficult.

[0053] In some embodiments, the self-healing dynamic interface layer is a polymer layer containing reversible dynamic covalent bonds. The self-healing dynamic interface layer has a thickness of 50-200 nm and completely covers the entire surface of the micro / nano-scale bumps and the surface of the solid electrolyte layer between adjacent bumps, forming a continuous and uninterrupted interface repair layer. The self-healing dynamic interface layer, being a polymer layer containing reversible dynamic covalent bonds, is used to achieve autonomous crack healing through reversible recombination of chemical bonds when microcracks occur at the interface. The reversible dynamic covalent bonds include Diels-Alder bonds.

[0054] Specifically, the self-healing dynamic interface layer is a key functional structure in solid-state batteries. Its core function is to dynamically repair microcracks at the interface, alleviate stress, and maintain ion transport efficiency. The self-healing dynamic interface layer is typically composed of the following four types of materials working together:

[0055] 1. Dynamically bonded polymer matrices, commonly including polyether polyurethanes (PTMG-HDI-BHDS), dynamically imine-bonded elastomers, and disulfide-bonded crosslinked polymers. Dynamic bonds (such as disulfide bonds and imine bonds) can achieve crack healing through reversible fracture-recombination when the interface cracks, while hydrogen bond networks provide rapid physical crosslinking-assisted repair.

[0056] 2. Ion-conducting media include composite systems containing lithium salts (such as LiFSI) and ionic liquids (such as triethylene glycol dimethyl ether), or liquid gallium-based alloys (primarily gallium-indium-tin, with additives such as bismuth and zinc). The liquid alloy solidifies during lithium insertion and liquefies during delithiation, adapting to interface deformation through solid-liquid conversion. The ionic liquid combines with the lithium salt to form a dynamic environment with high ionic conductivity, ensuring unimpeded ion transport during the repair process.

[0057] 3. Reinforcing fillers and interface modifiers include: Inorganic nanoparticles: such as amino-functionalized ZIF nanomaterials and modified hexagonal boron nitride (h-BN), used to improve mechanical strength and thermal conductivity. Coupling agents: silane coupling agents (such as KH550) and isopropyl titanate, to enhance the interfacial bonding between the polymer and the electrode / electrolyte. ZIF nanomaterials form hydrogen bonds with the polymer matrix through amino groups, while providing ion transport channels; h-BN binds to the polymer chains through π-π stacking, constructing a thermally conductive network.

[0058] 4. Auxiliary functional additives include: corrosion inhibitors: benzimidazole (BIM) and dichloromethylbenzimidazole (2CBI), which inhibit interfacial side reactions; antioxidants: vitamin E and hindered phenolic compounds, which prevent polymer oxidative degradation. During the repair process, the corrosion inhibitors are released to form a passivation film protecting the electrode surface; the antioxidants extend the material's service life.

[0059] In some embodiments, the waveform structure of the solid electrolyte layer is one of a sine wave structure, a square wave structure, or a triangular wave structure.

[0060] Specifically, the sinusoidal structure exhibits a continuous and smooth periodic curve shape, with its contour conforming to the law of a sine function: the peaks and troughs transition naturally through the arc-shaped surface, without obvious sharp edges or turns. The smooth arc-shaped surface can evenly disperse the interfacial stress during charge-discharge cycles, avoiding crack initiation caused by local stress concentration, making it particularly suitable for long-term cycling scenarios. The continuous and uninterrupted surface allows the contact area between the electrolyte and the electrode to form a complete closed loop, resulting in smoother ion transport paths and smaller interfacial impedance fluctuations. During the pressing process, the arc-shaped structure can adapt to the slight undulations on the electrode surface through elastic deformation, reducing poor contact caused by processing errors, making it suitable for the field of power batteries with high requirements for cycle stability.

[0061] The square wave structure consists of alternating horizontal planes and vertical surfaces, presenting a "stepped" periodic shape: the peaks and troughs are parallel planar segments, and the connecting parts are vertical or near-vertical surfaces. The horizontal planar segments can form a large area of ​​parallel contact, which, combined with the lateral contact of the vertical surfaces, creates a "mortise and tenon" interlocking between the stepped structure and the gradient pores of the electrodes. The vertical surfaces can be embedded into the depth of the electrodes' pores, enhancing the mechanical locking force at the interface. The uniform thickness of the planar segments reduces local accumulation of electrolyte material, saving electrolyte usage compared to a sine wave for the same contact area, making it suitable for applications with high power performance requirements (such as energy storage batteries).

[0062] The triangular wave structure exhibits a zigzag, periodic shape, with peaks formed by the intersection of two symmetrical, inclined straight lines. Adjacent peaks are connected to troughs by these inclined straight lines, creating an overall profile resembling a continuous arrangement of triangles. The inclined sides act as guides during the pressing process, directing the electrode material towards the troughs and reducing interfacial bubble residue. The straight inclined sides can linearly match the gradient porosity structure of the electrode, resulting in a uniform change in contact pressure from peak to trough, adapting to the gradient distribution of porosity. Compared to the complex curved surface of a sine wave, the straight contour of the triangular wave is easier to process using injection molds, simplifying dimensional accuracy control. It is suitable for mass production in the consumer electronics battery field.

[0063] In some embodiments, the pores in the gradient pore structure exhibit a continuous, gradual distribution from the interface side near the solid electrolyte layer to the current collector side away from the solid electrolyte layer. The number of pores gradually decreases with distance from the solid electrolyte layer, and the overall pore density decreases in a stepwise manner from the interface side to the current collector side. The dense distribution of pores in the interface region near the solid electrolyte layer provides embedding space for micro / nano-scale bumps on the surface of the solid electrolyte layer. The gaps between pores can accommodate the bump structure and fill the microscopic voids in the interface region, forming a complementary interlocking structure of pores and bumps. The pore size gradually decreases with distance from the solid electrolyte layer, with larger and more uniformly distributed pores on the interface side, providing ample space for bump embedding. As the structure extends towards the current collector side, the pore size gradually decreases, while the spacing between pores gradually increases, resulting in a smooth increase in electrode structure density. The gradient distribution of pores has no obvious stratification boundaries. Through continuous, gradual changes in density and size, a stress-free transition of the electrode material from a loose structure on the interface side to a dense structure on the current collector side is achieved, buffering the interfacial stress caused by the difference in expansion and contraction between the electrode and the electrolyte.

[0064] "Porosity" refers to the actual number of pores per unit volume. Starting from the interface side of the electrode near the solid electrolyte layer and moving away from the electrolyte layer and closer to the current collector: in the high-porosity region on the interface side, the number of pores distributed per cubic millimeter is greater;

[0065] "Porosity" refers to the proportion of the total pore volume to the electrode volume in the area (i.e., porosity). "Stepwise decrease" emphasizes that this density change presents a phased gradient characteristic: The first stage (high porosity layer on the interface side): The area near the solid electrolyte layer is a high porosity region with the highest porosity (30-50%). At this time, there are many pores, which are densely distributed and the overall structure is more loose. The purpose is to provide sufficient embedding space for the electrolyte bumps and reserve buffer gaps for expansion and contraction; The second stage (intermediate transition layer): The intermediate region transitioning towards the current collector. The first stage is a medium-porosity region with moderate porosity (30-35%). The number of pores is reduced compared to the first stage, and the density is also lower, achieving a smooth transition from "loose" to "dense" and avoiding stress concentration caused by abrupt density changes. The third stage (low-porosity layer on the current collector side): The area near the current collector is a low-porosity region with the lowest porosity (10-20%), the fewest pores, and the lowest density, resulting in a more compact overall structure. The aim is to ensure the mechanical strength of the electrode-current collector contact area and reduce the space occupied by the active material to increase energy density. Here, "stepped" does not refer to obvious "steps" or "faults," but rather to a gradient division of pore density from "high → medium → low" through process control, with no obvious interfaces between regions, achieving a continuous transition in density.

[0066] As the electrode penetrates deeper, the number of pores per unit volume gradually decreases (the number of voids is significantly reduced). Near the current collector, in the low-porosity region, the number of pores per unit volume reaches its minimum (only a few tiny pores remain). This reduction in pore number is essentially consistent with the stepwise decrease in density: the reduction in number directly leads to a decrease in the pore ratio (density) per unit volume, while the stepwise decrease clearly defines the phased nature of this reduction. High-number, high-density pores on the interface side can accommodate the electrolyte's micro-nano bumps, increasing the contact area and buffering stress. Gradually decreasing the number and density towards the current collector side can progressively improve the electrode's structural strength, avoiding insufficient mechanical properties due to overall porosity. The smooth, stepwise transition eliminates interfacial stress caused by abrupt density changes, ensuring the electrode is less prone to cracking due to expansion and contraction during cycling, while simultaneously guiding ions smoothly from the electrolyte to the electrode interior.

[0067] In some embodiments, the total thickness of the solid electrolyte layer is 10-100 μm, the thickness of the positive electrode is 20-300 μm, and the thickness of the negative electrode is 10-200 μm. The solid electrolyte layer has a core-shell structure, with a sulfide electrolyte core and a 5-10 nm Li3BO3 layer coated using atomic layer deposition (ALD) technology.

[0068] In one embodiment, the solid electrolyte layer has a specific structure in which the core body is Li7P3S. 11 The sulfide electrolyte forms the basic framework of the waveform structure, with a thickness of 25-70 μm, accounting for 85-90% of the total thickness. The outer shell is a uniformly coated Li3BO3 film, 5-10 nm thick, completely covering all surfaces of the core, including the waveform outline and bump structure, forming a dense protective layer. The micro / nano-scale bump array consists of frustum-shaped bumps uniformly distributed on both sides of the waveform surface of the solid electrolyte layer, with a bump density of 50-100 bumps / mm². Individual bumps are 2-4 μm high, with a base diameter of 8-15 μm and a top diameter that is 1 / 2-2 / 3 of the base diameter. Adjacent bumps are spaced 25-40 μm apart, arranged in a matrix pattern, and distributed in both peak and trough regions. The self-healing dynamic interface layer completely covers all bump surfaces and the waveform areas on both sides of the electrolyte layer, with a thickness of 80-150 nm, forming a continuous thin film. The material is a polyimide-epoxy copolymer containing Diels-Alder bonds, which is tightly attached to the surface of the Li3BO3 shell and maintains a uniform thickness on the top and sides of the protrusions.

[0069] In some feasible embodiments, a first conductive transition layer is provided on the side of the positive electrode away from the solid electrolyte layer. The first conductive transition layer is a composite layer of conductive carbon nanotubes and graphene with a thickness of 1-5 μm.

[0070] The positive electrode sheet has a rectangular sheet structure with a thickness of 100-200μm. The side facing the solid electrolyte layer is a first waveform surface that matches the electrolyte waveform, and the waveform profile is completely consistent with one side of the solid electrolyte layer. The other side is a planar structure with a first conductive transition layer covering the surface.

[0071] A three-layer gradient structure from the electrolyte side to the current collector side; the first layer (composite layer): accounting for 1 / 5 of the thickness, with a thickness of 20-40 μm. Constructed from LiNi 0.8 Co 0.1 Mn 0.1 It is composed of O2 and 25-30 vol% Li3BO3, exhibiting a porous structure with a porosity of 40-50%. The pores are irregularly distributed, with a higher pore density near the electrolyte side. The coefficient of thermal expansion is 12 × 10⁻ 6 / ℃, and the coefficient of thermal expansion of the solid electrolyte layer (9×10⁻) 6 ( / ℃) is close.

[0072] Second layer (transition layer): accounting for 1 / 5 of the thickness, with a thickness of 20-40 μm. LiNi 0.8 Co 0.1 Mn 0.1 The O2 content is increased to 85-90 vol%, and the Li3BO3 content is reduced to 10-15 vol%. The porosity is 30-35%, with slightly smaller and more uniformly distributed pore sizes compared to the first layer. The coefficient of thermal expansion is reduced to 10 × 10⁻⁻⁻⁻⁶. 6 / ℃, to achieve a smooth transition with the first layer.

[0073] The third layer (pure active material layer): accounting for 3 / 5 of the total thickness, with a thickness of 60-120 μm. It is pure LiNi. 0.8 Co 0.1 Mn 0.1 The O2-active material has a porosity of 10-20%, with the porosity decreasing gradually, and the porosity being slightly larger near the second layer. The coefficient of thermal expansion is stable at 8×10⁻⁻. 6 / ℃, matching the thermal expansion characteristics of the current collector.

[0074] The first conductive transition layer is tightly attached to the planar side of the positive electrode away from the electrolyte, with a thickness of 3-5 μm, and is a uniform thin film. It is composed of a three-dimensional conductive network formed by interwoven carbon nanotubes with a diameter of 5-10 nm, graphene sheets with a thickness of 0.34 nm, and nickel-coated carbon fibers with a diameter of 50-100 nm. The carbon fibers are randomly distributed, and the carbon nanotubes and graphene sheets uniformly fill the gaps.

[0075] In some feasible embodiments, a second conductive transition layer is provided on the side of the negative electrode away from the solid electrolyte layer. The second conductive transition layer is a composite layer of conductive carbon black and carbon fiber with a thickness of 1-5 μm.

[0076] Specifically, the negative electrode sheet is symmetrically distributed with the positive electrode sheet, and has a rectangular sheet structure with a thickness of 80-150 μm. The side facing the solid electrolyte layer is a second wave-shaped surface, which perfectly matches the wave pattern of the other side of the electrolyte layer. The other side is a planar structure, covered by a second conductive transition layer.

[0077] A three-layer gradient structure from the electrolyte side to the current collector side:

[0078] First layer (composite layer): accounting for 1 / 4 of the total thickness, with a thickness of 20-37.5 μm. It is composed of graphite and 25-30 vol% Li3BO3, with a porosity of 40-50% and a coefficient of thermal expansion of 11 × 10⁻⁻⁻⁶. 6 / ℃.

[0079] Second layer (transition layer): accounting for 1 / 4 of the total thickness, with a thickness of 20-37.5 μm. Graphite content 85-90 vol%, Li3BO3 content 10-15 vol%, porosity 30-35%, and coefficient of thermal expansion 9 × 10⁻ 6 / ℃.

[0080] The third layer (pure active material layer): accounting for 2 / 4 of the total thickness, with a thickness of 40-75 μm. It is made of pure graphite material with a porosity of 10-20% and a coefficient of thermal expansion of 7 × 10⁻⁻⁻⁻⁴. 6 / ℃.

[0081] The second conductive transition layer, attached to the planar side of the negative electrode away from the electrolyte, is 3-5 μm thick. It consists of conductive carbon black (20-30 nm particle size), carbon fibers, and copper-coated carbon nanotubes, with a volume resistivity ≤5×10⁻⁻. 5 Ω・cm, forming a uniform conductive thin film

[0082] Secondly, the present invention also provides a solid-state battery, comprising at least two of the above-described cell structures, wherein the cell structures are stacked sequentially, and a positive current collector is disposed outside the first conductive transition layer of the outermost positive electrode sheet, and a negative current collector is disposed outside the second conductive transition layer of the outermost negative electrode sheet. The positive current collector is press-fitted to the first conductive transition layer, and the negative current collector is press-fitted to the second conductive transition layer. The positive current collector is an aluminum foil or an aluminum alloy foil with a thickness of 6-15 μm; the negative current collector is a copper foil or a copper alloy foil with a thickness of 6-15 μm.

[0083] Thirdly, the present invention also provides a battery manufacturing apparatus, including a mold opening and closing unit for opening or closing an injection mold, wherein the inner wall of the injection mold cavity is provided with a micro-nano pit array that matches the micro-nano-level bump array, and the mold cavity is used to form the core of the solid electrolyte layer of the above-mentioned cell structure.

[0084] An atomic layer deposition unit is used to deposit a shell on the surface of the solid electrolyte layer core, the atomic layer deposition unit comprising a precursor supply device and a vacuum reaction chamber;

[0085] A pressing unit is used to press the positive electrode sheet, the solid electrolyte layer and the negative electrode sheet together. The pressing head surface of the pressing unit is provided with a waveform structure that matches the first waveform surface and the second waveform surface.

[0086] A coating unit is used to coat the surface of the micro-nano-scale bump array with a self-healing dynamic interface layer material, and the coating unit is manufactured using an aerosol jet printing device.

[0087] Fourthly, the present invention also provides a battery manufacturing process for forming the above-mentioned solid-state battery cell structure, comprising the following steps:

[0088] S1: Preparation of solid electrolyte layer: Molten electrolyte is injected into the mold cavity of the injection mold, cooled and demolded to obtain a solid electrolyte layer with a waveform structure and micro-nano-scale bump array.

[0089] S11: Molten sulfide electrolyte is injected into the mold cavity of an injection mold, cooled, and then demolded to obtain a solid electrolyte core with a wave-like structure and a micro / nano-scale bump array; specifically, a melt injection molding process is used to inject the sulfide electrolyte (such as Li7P3S) into the mold cavity. 11 The core is injected into a precision-machined waveform cavity, with the inner wall of the cavity pre-designed with micro-nano pit structures that match the bump array. During cooling, the temperature is controlled at a rate of 5-10℃ / min to avoid internal stress, ensuring waveform contour accuracy (peak / trough error ≤2μm) and bump integrity (height deviation ≤0.5μm). After demolding, the core surface roughness is controlled to Ra≤10nm, providing a smooth substrate for subsequent shell deposition.

[0090] S12: The solid electrolyte core is placed in the vacuum reaction chamber of the atomic layer deposition unit. A 5-10 nm Li3BO3 shell is deposited using Li(tmhd)3 and B2H6 as precursors. Specifically, the vacuum reaction chamber pressure is maintained at 1-5 Torr. Atom-level layer-by-layer growth is achieved using Li(tmhd)3 (lithium source) and B2H6 (boron source) as precursors through alternating pulses (Li source pulse 0.5s → purge 2s → B source pulse 0.5s → purge 2s). The deposition temperature is controlled at 150-200℃ to ensure that the precursors are fully decomposed and uniformly coat all surfaces of the core (including the top of the bumps, sides, and wave slopes), ultimately forming a dense 5-10 nm film that isolates the sulfides from side reactions with air / electrode.

[0091] S13: An aerosol jet printing device is used to spray a dynamic covalent polymer solution containing Diels-Alder bonds onto the surface of the micro / nano-scale bump array, forming a 50-200 nm thick self-healing dynamic interface layer through UV curing. Specifically, the dynamic covalent polymer solution (a polyimide-epoxy copolymer containing Diels-Alder bonds, with a solid content of 10-15%) is atomized through a 0.1 mm nozzle and sprayed at a pressure of 0.5 MPa under an inert atmosphere (Ar gas protection) to ensure complete coverage of the bump surface without droplet aggregation. UV curing uses a 365 nm wavelength, an energy density of 500-800 mJ / cm², and a curing time of 30-60 s, causing the polymer to crosslink and form a continuous 80-150 nm film with a thickness deviation ≤10 nm.

[0092] S2: Preparation of positive electrode sheet: Prepare positive electrode slurry, inject the positive electrode slurry into a mold with a first wave surface, form a first wave surface with a gradient pore structure through gradient sintering process, bake and roll and demold, and coat a first conductive transition layer on the side away from the first wave surface.

[0093] A positive electrode slurry is prepared by coating it in two stages. The first stage is a composite slurry containing 10-30 vol% Li3BO3 with a thickness of 20-30 μm, and the second stage is a pure positive electrode active material slurry with a thickness of 100-150 μm. The positive electrode slurry is injected into a mold with a first wave-shaped surface, and a first wave-shaped surface with a gradient pore structure is formed by gradient sintering. After baking and rolling, the slurry is demolded, and a first conductive transition layer is coated on the side away from the first wave-shaped surface.

[0094] The specific composite slurry (first layer) is made of LiNi 0.8 Co 0.1 Mn 0.1 O2, Li3BO3 (10-30 vol%), and binder (PVDF) are mixed in a ratio of 85:10:5, with NMP as the solvent and a solid content of 50-60%. A 20-30 μm wet film is formed by doctor blade coating. The pure active material slurry (second and third layers) does not contain Li3BO3, but its solid content is increased to 60-70%, with a total coating thickness of 100-150 μm, forming a compositional gradient with the composite slurry layer.

[0095] Pre-sintering stage (30-60℃, 1-2h): Slowly evaporate the solvent (NMP residue ≤0.1%) to avoid surface cracking caused by rapid drying, while allowing the slurry particles to initially accumulate and form a loose skeleton.

[0096] Heating stage (5-10℃ / min to 100-150℃): Low heating rate reduces thermal stress and prevents interlayer delamination; as the temperature rises, Li3BO3 gradually melts and fills part of the gaps, regulating the pore distribution.

[0097] During the heat preservation stage (100-150℃, 2-3h): the adhesive decomposes (removes organic residues) and particles fuse together, resulting in a composite layer with a porosity of 40-50% (suitable for electrolyte bump embedding) and a pure active material layer with a low porosity of 10-20% (ensuring structural strength). The porosity between the two layers changes continuously and gradually (without a clear interface).

[0098] After baking and rolling, the surface roughness of the positive electrode is controlled to Ra≤50nm. The first conductive transition layer (carbon nanotubes + graphene + nickel-coated carbon fibers, solid content 5%) is coated by a doctor blade, with a thickness of 3-5μm. After lamination, the volume resistivity is ≤1×10⁻ 4 Ω・cm

[0099] S3: Preparation of negative electrode sheet: Prepare negative electrode slurry, inject the negative electrode slurry into a mold with a second wave surface, form a second wave surface with a gradient pore structure through gradient sintering process, bake and roll and demold, and coat a second conductive transition layer on the side away from the second wave surface.

[0100] A negative electrode slurry is prepared by coating it in two stages. The first stage is a composite slurry containing 10-30 vol% Li3BO3 with a thickness of 20-30 μm, and the second stage is a pure negative electrode active material slurry with a thickness of 80-120 μm. The negative electrode slurry is injected into a mold with a second wave-shaped surface, and a second wave-shaped surface with a gradient pore structure is formed by gradient sintering. After baking and rolling, the material is demolded, and a second conductive transition layer is coated on the side away from the second wave-shaped surface.

[0101] The specific symmetrical design with the positive electrode process has the following core differences:

[0102] The slurry components are replaced with graphite (the composite layer contains 10-30 vol% Li3BO3), and the pure active material layer is graphite;

[0103] After gradient sintering, the composite layer has a porosity of 40-50%, the pure graphite layer has a porosity of 10-20%, and the coefficient of thermal expansion is 11×10⁻⁻⁻⁶. 6 / ℃ gradient reduced to 7×10⁻ 6 / ℃, matching the characteristics of the electrolyte layer;

[0104] The second conductive transition layer uses conductive carbon black + copper-coated carbon nanotubes, with a volume resistivity ≤5×10⁻⁻ 5 Ω・cm, enhances electron conduction.

[0105] S4: Align the first wave surface of the positive electrode, one side of the solid electrolyte layer, and the second wave surface of the negative electrode in sequence, and press them together to form a two-cell battery; use hot pressing process (temperature 60-80℃, pressure 5-10MPa) to make the electrolyte bumps embed into the high porosity region of the positive / negative electrode through the self-healing layer to form mechanical anchoring, and the interface contact resistance after pressing is ≤50Ω・cm².

[0106] S5: Stack at least two of the aforementioned binary cells, press a positive current collector onto the first conductive transition layer of the outermost positive electrode, and press a negative current collector onto the second conductive transition layer of the outermost negative electrode to form a cell; the alignment accuracy of the binary cells is controlled within ±10μm during stacking, and the current collector is bonded to the conductive transition layer by ultrasonic pressing (power 50-100W) to form a gapless connection.

[0107] S6: Bake the battery cell at a temperature of 80-120℃ for 2-4 hours. Vacuum baking at 80-120℃ (vacuum degree ≤1Pa) removes trace amounts of moisture (water content ≤50ppm) and promotes the interfacial wetting of the self-healing layer with the electrode / electrolyte, thereby improving long-term stability.

[0108] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A solid-state battery cell structure, comprising a positive electrode, a solid electrolyte layer, and a negative electrode arranged sequentially; wherein the solid electrolyte layer has a wave-like structure, characterized in that: Both sides of the solid electrolyte layer are provided with micro-nano-scale bump arrays, and the surface of the bumps is provided with a self-healing dynamic interface layer. The self-healing dynamic interface layer is a polymer layer containing reversible dynamic covalent bonds, and the thickness of the self-healing dynamic interface layer is 50-200nm. The positive electrode sheet has a first waveform surface on the side facing the solid electrolyte layer that matches the waveform structure of one side of the solid electrolyte layer. The first waveform surface has a gradient pore structure. The negative electrode sheet has a second waveform surface on the side facing the solid electrolyte layer that matches the waveform structure of the other side of the solid electrolyte layer. The second waveform surface has a gradient pore structure. The pores in the gradient pore structure are continuously and gradually distributed from the interface side near the solid electrolyte layer to the current collector side away from the solid electrolyte layer. The number of pores gradually decreases as they move away from the solid electrolyte layer. The overall pore density decreases in a stepwise manner from the interface side to the current collector side. The pore size gradually decreases as they move away from the solid electrolyte layer. As they extend towards the current collector side, the pore size gradually decreases and the spacing between the pores gradually increases. The two sides of the solid electrolyte layer are coupled to the first waveform surface of the positive electrode and the second waveform surface of the negative electrode through the micro-nano-level bump array and the self-healing dynamic interface layer, respectively.

2. The cell structure of the solid-state battery as described in claim 1, characterized in that: The bumps in the micro-nano scale bump array are conical or frustum-shaped, with a bump height of 1-5 μm, a base diameter of 5-20 μm, and a spacing of 20-50 μm between adjacent bumps.

3. The cell structure of the solid-state battery as described in claim 1, characterized in that: The waveform structure of the solid electrolyte layer is one of a sine wave structure, a square wave structure, or a triangular wave structure.

4. The cell structure of the solid-state battery as described in claim 1, characterized in that: The total thickness of the solid electrolyte layer is 10-100 μm, the thickness of the positive electrode is 20-300 μm, and the thickness of the negative electrode is 10-200 μm.

5. The cell structure of the solid-state battery as described in claim 4, characterized in that: The positive electrode sheet is provided with a first conductive transition layer on the side away from the solid electrolyte layer. The first conductive transition layer is a composite layer of conductive carbon nanotubes and graphene with a thickness of 1-5 μm.

6. The cell structure of the solid-state battery as described in claim 4, characterized in that, The negative electrode sheet has a second conductive transition layer on the side away from the solid electrolyte layer. The second conductive transition layer is a composite layer of conductive carbon black and carbon fiber with a thickness of 1-5 μm.

7. A solid-state battery, characterized in that: The battery cell structure includes at least two of the cell structures described in any one of claims 1-6, wherein the cell structures are stacked sequentially, and a positive current collector is disposed outside the first conductive transition layer of the outermost positive electrode sheet after stacking, and a negative current collector is disposed outside the second conductive transition layer of the outermost negative electrode sheet, wherein the positive current collector is press-fitted to the first conductive transition layer, and the negative current collector is press-fitted to the second conductive transition layer.

8. A battery manufacturing apparatus, characterized in that: The device includes a mold opening and closing unit for opening or closing an injection mold. The inner wall of the injection mold cavity is provided with a micro-nano pit array that matches the micro-nano-level bump array. The mold cavity is used to form the solid electrolyte layer core of the cell structure according to any one of claims 1-6. An atomic layer deposition unit is used to deposit a shell on the surface of the solid electrolyte layer core, the atomic layer deposition unit comprising a precursor supply device and a vacuum reaction chamber; A pressing unit is used to press the positive electrode sheet, the solid electrolyte layer and the negative electrode sheet together. The pressing head surface of the pressing unit is provided with a waveform structure that matches the first waveform surface and the second waveform surface. A coating unit is used to coat the surface of the micro-nano-scale bump array with a self-healing dynamic interface layer material, and the coating unit is manufactured using an aerosol jet printing device.

9. A battery manufacturing process for forming the cell structure of a solid-state battery according to any one of claims 1-6, characterized in that, Includes the following steps: S1: Preparation of solid electrolyte layer: Molten electrolyte is injected into the mold cavity of injection mold, cooled and demolded to obtain a solid electrolyte layer with waveform structure and micro-nano-scale bump array; S2: Preparation of positive electrode sheet: Prepare positive electrode slurry, inject the positive electrode slurry into a mold with a first wave surface, form a first wave surface with a gradient pore structure through gradient sintering process, bake and roll and demold, and coat a first conductive transition layer on the side away from the first wave surface. S3: Preparation of negative electrode sheet: Prepare negative electrode slurry, inject the negative electrode slurry into a mold with a second wave surface, form a second wave surface with a gradient pore structure through gradient sintering process, bake and roll and demold, and coat a second conductive transition layer on the side away from the second wave surface. S4: Align the first wave-shaped surface of the positive electrode, one side of the solid electrolyte layer, and the second wave-shaped surface of the negative electrode in sequence, and press them together using a pressing unit to form a two-part battery; S5: Stack at least two of the aforementioned two-cell batteries, press a positive current collector onto the first conductive transition layer of the outermost positive electrode sheet, and press a negative current collector onto the second conductive transition layer of the outermost negative electrode sheet to form a battery cell. S6: Bake the battery cell at a temperature of 80-120℃ for 2-4 hours.

10. The battery manufacturing process according to claim 9, characterized in that, The gradient sintering process in steps S2 and S3 is as follows: pre-sintering at 30-60℃ for 1-2 hours, then heating to 100-150℃ at a rate of 5-10℃ / min and holding for 2-3 hours.

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