3D printing overhang slurry, electrode plate, battery cell and preparation method thereof, and solid-state battery

Abstract

The invention relates to the technical field of solid-state batteries, and discloses 3D printing overhang slurry which comprises composite powder, a binder, a surfactant and a solvent, the composite powder comprises inorganic solid electrolyte particles with the particle size distribution range of 0.01-2 microns and two-dimensional layered powder with the two-dimensional size of 0.6-2 microns, and the mass percent of the particles with the particle size within the range of 0.01-0.3 microns is 25%-50%; part of the inorganic solid electrolyte particles are embedded into the interlayer and / or lamellar surface of the two-dimensional layered powder. According to the 3D printing overhang slurry, high solid content and rheological property are taken into account, so that the 3D printing overhang slurry can be suitable for a 3D printing method, printability and high strength of the high-solid-content slurry are realized, the printing strength is ensured, the printing smoothness is also ensured, and a packaging structure with an expected effect can be obtained at a gap. The invention further discloses an electrode plate, a battery cell, a preparation method of the battery cell and a solid-state battery.

Description

Technical Field

[0001] This application relates to the technical field of solid-state batteries, for example, it relates to a 3D printed overhang slurry, an electrode sheet, a battery cell, and their preparation methods and solid-state batteries. Background Art

[0002] The negative overhang area refers to the part of the negative electrode sheet that extends beyond the positive electrode sheet in the length and / or width directions. This design is mainly to prevent the precipitation of lithium dendrites on the surface of the negative electrode during charging, which may pierce the separator and cause internal short circuit of the battery, leading to thermal runaway and improving the safety of the battery. However, since a relatively high assembly pressure is usually required during the preparation of all-solid-state batteries. When using the traditional electrode sheet with a larger negative electrode and a smaller positive electrode, due to the different sizes of the positive and negative electrode sheets, the force is uneven during the pressurized assembly of the solid-state battery, which easily causes the collapse of the negative overhang area and the contact between the positive and negative electrodes, resulting in battery short circuit.

[0003] Regarding the problem that the negative overhang area is prone to collapse during the assembly of the solid-state battery, resulting in the contact between the positive and negative electrodes and then causing battery short circuit, substances are mostly set / filled in the overhang voids corresponding to the negative overhang area for support to avoid the collapse of the negative overhang area during the assembly of the solid-state battery. Currently, the methods for setting / filling substances in the overhang voids are generally coating methods, pouring methods, etc. However, these methods for setting / filling substances cannot effectively control the amount of substances set / filled during the setting / filling process, resulting in the filling of the overhang voids not achieving the expected effect.

[0004] It should be noted that the information disclosed in the above background art section is only used to enhance the understanding of the background of this application, and therefore may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0005] To provide a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. This summary is not a comprehensive review, nor is it intended to identify key / important elements or delineate the scope of protection of these embodiments, but rather serves as a prelude to the detailed description that follows.

[0006] The embodiments of the present disclosure provide a 3D printed overhang slurry, an electrode sheet, a battery cell, and their preparation methods and solid-state batteries. The 3D printed overhang slurry can be applied to 3D printing methods, and the 3D printing methods can precisely control printing parameters such as the discharge amount, so as to obtain an overhang void filling effect with the expected result.

[0007] In some embodiments, the 3D printing overhang slurry includes: composite powder, binder, surfactant, and solvent. The mass ratio of the composite powder to the binder is 4 to 20:1, the mass ratio of the surfactant to the binder is 0.0005 to 0.02:1, and the solid content of the overhang slurry is 60% to 75%. Among them, the composite powder includes inorganic solid electrolyte particles and two-dimensional layered powder. The mass ratio of the inorganic solid electrolyte particles to the two-dimensional layered powder is 0.5 to 1.5:1. The particle size distribution range of the inorganic solid electrolyte particles is 0.01 to 2 μm, and the mass percentage of the first inorganic solid electrolyte particles with a particle size in the range of 0.01 to 0.3 μm is 25% to 50%. The two-dimensional size of the two-dimensional layered powder is 0.6 to 2 μm. Some of the inorganic solid electrolyte particles are embedded between the layers and / or on the surface of the flakes of the two-dimensional layered powder.

[0008] In some embodiments, the method for preparing the 3D printing overhang slurry includes: preparing each raw material according to the foregoing 3D printing overhang slurry; ball-milling and mixing the inorganic solid electrolyte particles and the two-dimensional layered powder to obtain composite powder; and mixing the composite powder with other raw materials to obtain the 3D printing overhang slurry.

[0009] In some embodiments, the electrode pole piece is a positive electrode pole piece or a negative electrode pole piece. When the electrode pole piece includes a positive electrode pole piece, the positive electrode pole piece includes an empty foil area, and the 3D printing overhang slurry is provided in the empty foil area. When the electrode pole piece includes a negative electrode pole piece, the negative electrode pole piece includes an overhang area, and the 3D printing overhang slurry is provided in the overhang area of the negative electrode pole piece. When the electrode pole piece includes a composite negative electrode pole piece with a solid electrolyte layer provided on both its two side surfaces and the negative electrode pole piece is the negative electrode pole piece, the 3D printing overhang slurry is provided on the surface of the solid electrolyte layer of the composite negative electrode pole piece corresponding to the overhang area of the negative electrode pole piece. Among them, the 3D printing overhang slurry is the foregoing 3D printing overhang slurry or the 3D printing overhang slurry prepared by the method for preparing the foregoing 3D printing overhang slurry.

[0010] In some embodiments, the battery cell includes alternately stacked positive electrode plates and negative electrode plates, and a solid electrolyte layer is disposed between adjacent positive electrode plates and negative electrode plates; at least one side of the negative electrode plate in the circumferential direction extends beyond the positive electrode plate to form an overhang region; wherein, a packaging structure is disposed in the overhanging void region corresponding to the overhang region; wherein, the packaging structure is obtained by 3D printing an overhang slurry in the overhanging void region; the 3D printing overhang slurry is the aforementioned 3D printing overhang slurry or the 3D printing overhang slurry prepared by the preparation method of the aforementioned 3D printing overhang slurry.

[0011] In some embodiments, the method for preparing the battery cell includes: preparing a positive electrode plate, a negative electrode plate and a solid electrolyte layer; wherein, the size of the negative electrode plate is larger than that of the positive electrode plate at least on one side in the circumferential direction, so that the negative electrode plate has an overhang region; wherein, the positive electrode plate is the aforementioned positive electrode plate, or the negative electrode plate is the aforementioned negative electrode plate or a combined negative electrode plate; alternately stacking the positive electrode plate and the negative electrode plate, and disposing a solid electrolyte layer between adjacent positive electrode plates and negative electrode plates to obtain a battery cell; wherein, a cured 3D printing overhang slurry is disposed at the overhang void of the battery cell.

[0012] In some embodiments, the solid-state battery includes: the aforementioned electrode plates; or, the aforementioned battery cells; or the battery cells prepared by the preparation method of the aforementioned battery cells.

[0013] The 3D printing overhang slurry, electrode plates, battery cells, their preparation methods and solid-state batteries provided by the embodiments of the present disclosure can achieve the following technical effects: The 3D printing overhang slurry of the embodiments of the present disclosure takes into account both high solid content and rheological properties, enabling it to be suitable for 3D printing methods, achieving printability and high strength of high-solid-content slurries, that is, ensuring printing strength and printing smoothness, so as to obtain a packaging structure with the desired effect at the overhang void. At the same time, the compounding of inorganic solid electrolyte particles with a large particle size distribution range and two-dimensional layered powders, then, inorganic solid electrolyte particles adapted to the interlayer spacing and surface defects of the two-dimensional layered powders can be embedded into the interlayer and / or surface of the two-dimensional layered powders. Then, the surface defects of the two-dimensional layered powder flakes provide affinity sites for lithium ions, and the embedded inorganic solid electrolyte particles cooperate to construct a continuous lithium ion transport path, reducing the short-circuit risk and capacity loss caused by lithium precipitation at the negative electrode side edge, achieving the expected effect of filling the overhang void.

[0014] In the method for preparing the 3D printed overhang slurry according to the embodiments of the present disclosure, the inorganic solid electrolyte particles and the two-dimensional layered powder are mixed evenly by ball milling to obtain a composite powder, and then the composite powder is mixed evenly with other raw materials. During the ball milling process, the strong collision and friction between the inorganic solid electrolyte particles and the two-dimensional heat-conducting material will further create abundant defects on the surface of the two-dimensional layered material, providing a large number of affinity sites for lithium ions. Moreover, under the action of the grinding shear force, the amount of inorganic solid electrolyte particles embedded between the layers and / or on the surface of the two-dimensional layered powder can be increased, thereby synergistically constructing a better continuous lithium ion transmission path and reducing the short-circuit risk and capacity loss caused by lithium precipitation at the edge of the negative electrode side.

[0015] The electrode pole piece according to the embodiments of the present disclosure can print and set an overhang encapsulation structure by a 3D printing method, and can accurately control the printing amount, so that parameters such as the thickness and uniformity of the encapsulation structure can be well controlled, and the printing speed is fast and the efficiency is high.

[0016] The above general description and the following description are only exemplary and explanatory, and are not used to limit the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] One or more embodiments are exemplarily illustrated by corresponding drawings. These exemplary illustrations and the drawings do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings are shown as similar elements. The drawings do not constitute a scale limitation, and among them: Figure 1 is a schematic structural diagram of a part of the composite powder in a 3D printed overhang slurry provided by the embodiments of the present disclosure; Figure 2 is a flowchart of a method for preparing a 3D printed overhang slurry provided by the embodiments of the present disclosure; Figure 3 is a flowchart of a method for preparing an electric core provided by the embodiments of the present disclosure; Figure 4 is a rheological property curve diagram of the 3D printed overhang slurry provided by the embodiments of the present disclosure.

[0018] REFERENCE SIGNS: 11. Two-dimensional layered powder; 12. Inorganic solid electrolyte particles. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] In order to more comprehensively understand the features and technical content of the embodiments of the present disclosure, the implementation of the embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. The attached drawings are for reference and illustration only and are not intended to limit the embodiments of the present disclosure. In the following technical description, for the sake of explanation, numerous details are provided to provide a thorough understanding of the disclosed embodiments. However, one or more embodiments may still be implemented without these details. In other cases, well-known structures and devices may be shown in a simplified manner to simplify the drawings.

[0020] In the embodiments of the present disclosure, terms such as "first" and "second" in the specification, claims, and the above-mentioned drawings are used to distinguish similar objects and do not necessarily describe a specific order or sequence. It should be understood that such terms can be interchanged under appropriate circumstances to facilitate understanding of the embodiments of the present disclosure described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion.

[0021] In the embodiments of the present disclosure, the orientation or positional relationship indicated by terms such as "upper", "lower", "inner", "middle", "outer", "front", and "back" is based on the orientation or positional relationship shown in the drawings. These terms are mainly used to better describe the embodiments of the present disclosure and their embodiments, and are not intended to limit that the indicated devices, elements, or components must have a specific orientation or be constructed and operated in a specific orientation. Moreover, in addition to being able to represent an orientation or positional relationship, some of the above terms may also be used to represent other meanings. For example, the term "upper" may also be used to represent a certain attachment relationship or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in the embodiments of the present disclosure can be understood according to specific circumstances.

[0022] In addition, the terms "arranged", "connected", and "fixed" should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or there can be internal communication between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present disclosure can be understood according to specific circumstances.

[0023] Unless otherwise specified, the term "plurality" means two or more.

[0024] In the embodiments of the present disclosure, the character " / " indicates that the objects before and after are in an "or" relationship. For example, A / B means: A or B.

[0025] The term "and / or" is a description of the associated relationship of an object and indicates that three relationships can exist. For example, A and / or B means: A or B, or, A and B.

[0026] It should be noted that, without conflict, the embodiments in the present disclosure and the features in the embodiments may be combined with each other.

[0027] Combined with Figure 1 As shown, the present disclosure provides a 3D printing overhang slurry, including: composite powder, binder, surfactant and solvent. The mass ratio of the composite powder to the binder is 4-20:1, the mass ratio of the surfactant to the binder is 0.0005-0.02:1, and the solid content of the overhang slurry is 60%-75%; wherein, the composite powder includes inorganic solid electrolyte particles and two-dimensional layered powder, and the mass ratio of the inorganic solid electrolyte particles to the two-dimensional layered powder is 0.5-1.5:1; the particle size distribution range of the inorganic solid electrolyte particles is 0.01-2 μm, and the mass percentage of the first inorganic solid electrolyte particles with a particle size in the range of 0.01-0.3 μm is 25%-50%; the two-dimensional size of the two-dimensional layered powder is 0.6-2 μm; part of the inorganic solid electrolyte particles 12 are embedded into the interlayer and / or the surface of the sheet layer of the two-dimensional layered powder 11.

[0028] The 3D printing overhang slurry of the embodiments of the present disclosure takes into account both high solid content and rheological properties, enabling it to be applicable to 3D printing methods, achieving the printability and high strength of high-solid-content slurries, that is, ensuring both printing strength and printing smoothness, so as to obtain an encapsulation structure with the expected effect at the overhang gap. At the same time, the compounding of inorganic solid electrolyte particles with a large particle size distribution range and two-dimensional layered powder, then, the inorganic solid electrolyte particles adapted to the interlayer spacing and the surface defects of the sheet layer of the two-dimensional layered powder can be embedded into the interlayer and / or the surface of the sheet layer of the two-dimensional layered powder. Then, the surface defects of the sheet layer of the two-dimensional layered powder provide affinity sites for lithium ions, and the co-embedded inorganic solid electrolyte particles build a continuous lithium ion transmission path, reducing the short-circuit risk and capacity loss caused by lithium precipitation at the edge of the negative electrode side, achieving the expected effect of filling the overhang gap.

[0029] The solid content of the 3D printed overhang slurry in the embodiments of the present disclosure is 60% - 75%, which has a very high solid content. By combining inorganic solid electrolyte particles with different particle sizes and two-dimensional materials and regulating surfactants, the rheological properties of the slurry are significantly improved, enabling the 3D printed overhang slurry with this solid content to achieve a balance between the rheological properties and high solid content of the slurry. This results in a reasonable number of solid phase particles in the 3D printed overhang slurry, with appropriate particle spacing, thus having reasonable rheology, making it suitable for 3D printing methods, ensuring the processability and stability of 3D printing, and guaranteeing the strength and density of the printed overhang encapsulation structure. It can be understood that the solid content of the 3D printed overhang slurry can be the mass solid content or the volume solid content, without limitation. Optionally, the solid content of the 3D printed overhang slurry is the mass solid content. The adjustment of the solid content is achieved through the addition amount of the solvent, that is, the amount of the solvent in the 3D printed overhang slurry of the present disclosure is determined according to the solid content of the slurry. The type of the solvent is not limited.

[0030] Optionally, the solvent includes one or more of N,N-dimethylacetamide, N-methylpyrrolidone, acetonitrile, toluene, xylene, butyl butyrate, isobutyl butyrate, ethyl acetate, chloroform, tetrahydrofuran, and alkanes.

[0031] Optionally, the solid content of the 3D printed overhang slurry is 60% - 70%. Optionally, the solid content of the 3D printed overhang slurry is 60% - 65%.

[0032] Optionally, the solid content of the 3D printed overhang slurry is 60%, 62%, 65%, 70%, or 75%, or any value within the range of 60% - 75%.

[0033] The viscosity of the 3D printed overhang slurry in the embodiments of the present disclosure is 2 - 10 Pa·s -1 . The viscosity is low and the rheology is good.

[0034] In the 3D printing overhang slurry according to the embodiments of the present disclosure, by controlling the mass percentage of the first inorganic solid electrolyte particles with a particle size in the range of 0.01 to 0.3 μm, the usage amount of the first inorganic solid electrolyte particles in the small particle size range is ensured, so that at least part of the nano-scale first inorganic solid electrolyte particles can be embedded between the layers and / or on the surface of the two-dimensional layered powder, and the nano-inorganic solid electrolyte small particles act as a "bridge" between the two-dimensional layered materials. The anisotropy of the two-dimensional material is complementary to the random orientation of the nano-scale inorganic solid electrolyte particles, realizing a quasi-isotropic ion-conducting functional three-dimensional network, effectively reducing the ion transport resistance inside the battery, and improving the safety and cycle life of the battery. Moreover, the small particle size solid electrolyte particles can flow in the gaps between the large particle size solid electrolyte particles, weakening the flow resistance between the particles, further reducing the viscosity of the slurry and improving the rheological properties of the slurry. Moreover, the two-dimensional layered thermal conductive material can also be used as a lubricant and combined with the combination of different particle sizes of the inorganic solid electrolyte particles to improve the rheological properties of the slurry, thereby facilitating the construction of a continuous ion transport path in the overhang gap and improving the density and strength of the overhang encapsulation structure after forming.

[0035] Optionally, the mass percentage of the first inorganic solid electrolyte particles is 30% to 50%. Optionally, the mass percentage of the first inorganic solid electrolyte particles is 30% to 40%. Optionally, the mass percentage of the first inorganic solid electrolyte particles is 25%, 30%, 35%, 40%, 45%, 50%, or any value within 25% to 50%. It can be understood that the mass percentage of the first inorganic solid electrolyte particles refers to the mass percentage of the first inorganic solid electrolyte particles in all inorganic solid electrolyte particles.

[0036] Among the inorganic solid electrolyte particles, except for the first inorganic solid electrolyte, the particle size range of the remaining inorganic solid electrolyte particles is 0.3 to 2 μm. The inorganic solid electrolyte particles within this particle size range are not limited and can be determined according to actual situations.

[0037] In some embodiments, among the inorganic solid electrolyte particles, the mass percentage of the second inorganic solid electrolyte particles with a particle size in the range of 0.3 to 0.6 μm is 40% to 75%. In this embodiment, the proportion of the second inorganic solid electrolyte particles with a particle size in the range of 0.3 to 0.6 μm is limited, and it is compounded with the first inorganic solid electrolyte particles in the small particle size range to further improve the rheological properties of the slurry, construct a better continuous ion transport path, and further improve the density and strength of the overhang encapsulation structure.

[0038] Optionally, the composite powder is obtained by grinding and mixing inorganic solid electrolyte particles and two-dimensional layered powder. Through grinding, such as ball milling, the strong collision and friction between the inorganic solid electrolyte particles and the two-dimensional heat-conducting material will further create abundant defects on the surface of the two-dimensional layered material, providing a large number of affinity sites for lithium ions. Moreover, under the action of the grinding shear force, the amount of inorganic solid electrolyte particles embedded between the layers and / or on the surface of the two-dimensional layered powder can be increased, thereby synergistically constructing a better continuous lithium ion transmission path and reducing the short-circuit risk and capacity loss caused by lithium precipitation at the edge of the negative electrode side.

[0039] Optionally, the composite powder is obtained by ball milling and mixing inorganic solid electrolyte particles and two-dimensional layered powder. Optionally, it is obtained by high-energy ball milling and mixing. The ball milling parameters are determined according to actual requirements.

[0040] Optionally, the ball milling parameters include: the ball-to-material ratio is 10 - 40:1; and / or, the rotation speed is 400 - 600 rpm; and / or, the ball milling time is 1 - 2 h. Optionally, the ball-to-material ratio is 20 - 40:1.

[0041] Optionally, the inorganic solid electrolyte particles are composed of a first inorganic solid electrolyte and a second inorganic solid electrolyte, that is, the particle size distribution range of the inorganic solid electrolyte particles is 0.01 - 0.6 μm. In this embodiment, the inorganic solid electrolyte particles are two-stage particle size compounded particles, defined as two-stage compounded inorganic solid electrolyte particles. In this embodiment, the mass percentage of the first inorganic solid electrolyte is 25% - 50%, and the mass percentage of the second inorganic solid electrolyte particles is 50% - 75%.

[0042] Optionally, in the two-stage compounded inorganic solid electrolyte particles, the mass ratio of the second inorganic solid electrolyte particles to the first inorganic solid electrolyte particles is (4 - 7):(3 - 6). Optionally, the mass ratio of the second inorganic solid electrolyte particles to the first inorganic solid electrolyte particles is (5 - 6):(3 - 4).

[0043] Optionally, in the two-stage compounded inorganic solid electrolyte particles, the mass percentage of the first inorganic solid electrolyte is 30% - 50%, and the mass percentage of the second inorganic solid electrolyte particles is 50% - 70%.

[0044] Optionally, in the two-stage compounded inorganic solid electrolyte particles, the mass percentage of the first inorganic solid electrolyte is 30% - 40%, and the mass percentage of the second inorganic solid electrolyte particles is 60% - 70%.

[0045] Optionally, in the two-stage compounded inorganic solid electrolyte particles, the particle size ratio of the second inorganic solid electrolyte particles to the first inorganic solid electrolyte particles (defined as the first particle size ratio) is 1:0.03 to 0.4. That is, the specific particle sizes of the second inorganic solid electrolyte particles and the first inorganic solid electrolyte particles are determined within this particle size ratio range. Optionally, the first particle size ratio is 1:0.03 to 0.3; optionally, the first particle size ratio is 1:0.03 to 0.2. Optionally, the first particle size ratio is 1:0.03, 1:0.05, 1:0.1, 1:0.15, 1:0.2, 1:0.25, or 1:0.3, etc. By defining the first particle size ratio, the rheological properties of the slurry are further improved, a better continuous ion transport path is constructed, and the density and strength of the Overhang encapsulation structure are further increased.

[0046] In some embodiments, among the inorganic solid electrolyte particles, the third inorganic solid electrolyte particles with a particle size in the range of 0.6 to 2 μm, and the mass percentage of the third inorganic solid electrolyte particles is 0 to 20% and not 0. In this embodiment, among the inorganic solid electrolyte particles, the mass percentage of the second inorganic solid electrolyte particles with a particle size in the range of 0.3 to 0.6 μm is not limited as long as the sum of the first inorganic solid electrolyte particles, the second inorganic solid electrolyte particles, and the third inorganic solid electrolyte particles is 100%. The inorganic solid electrolyte particles of this embodiment are defined as three-stage compounded inorganic solid electrolyte particles.

[0047] In the three-stage compounded inorganic solid electrolyte particles of this embodiment, the mass percentage of the first inorganic solid electrolyte particles is 25% to 50%, the mass percentage of the second inorganic solid electrolyte particles is 40% to 75%, the mass percentage of the third inorganic solid electrolyte particles is 0 to 20% and not 0; and the sum of the three is 100%.

[0048] Optionally, in the three-stage compounded inorganic solid electrolyte particles, the mass ratio of the third inorganic solid electrolyte particles, the second inorganic solid electrolyte particles, and the first inorganic solid electrolyte particles is (0 to 2):(4 to 7):(3 to 6); and the third inorganic solid electrolyte particles are not 0. Optionally, the mass ratio of the third inorganic solid electrolyte particles, the second inorganic solid electrolyte particles, and the first inorganic solid electrolyte particles is (1 to 2):(5 to 6):(3 to 4).

[0049] Optionally, in the three-stage compounded inorganic solid electrolyte particles, the mass percentage of the first inorganic solid electrolyte particles is 25% to 50%, the mass percentage of the second inorganic solid electrolyte particles is 40% to 60%, and the mass percentage of the third inorganic solid electrolyte particles is 0% to 20% and not 0.

[0050] Optionally, in the ternary composite inorganic solid electrolyte particles, the mass percentage of the first inorganic solid electrolyte particles is 25% - 40%, the mass percentage of the second inorganic solid electrolyte particles is 40% - 60%, and the mass percentage of the third inorganic solid electrolyte particles is 5% - 20%.

[0051] Optionally, in the ternary composite inorganic solid electrolyte particles, the mass percentage of the first inorganic solid electrolyte particles is 30% - 40%, the mass percentage of the second inorganic solid electrolyte particles is 45% - 60%, and the mass percentage of the third inorganic solid electrolyte particles is 10% - 20%.

[0052] In the ternary composite inorganic solid electrolyte particles, the particle size ratio of the third inorganic solid electrolyte particles to the second inorganic solid electrolyte particles (defined as the second particle size ratio) is 1:0.25 - 0.6; the particle size ratio of the second inorganic solid electrolyte particles to the first inorganic solid electrolyte particles (the same as the aforementioned first particle size ratio) is 1:0.03 - 0.4.

[0053] Optionally, the second particle size ratio is 1:0.3 - 0.5. Optionally, the second particle size ratio is 1:0.35 - 0.45. Optionally, the second particle size ratio is 1:0.4. Optionally, the second particle size ratio is 1: 0.25, 1:0.3, 1:0.35, 1:0.4, 1:0.45, 1:0.5, 1:0. 55 or 1:0. 6, etc. By defining the second particle size ratio and the first particle size ratio, the rheological properties of the slurry are further improved, a better continuous ion transport path is constructed, and the density and strength of the Overhang encapsulation structure are further increased.

[0054] In the embodiments of the present disclosure, the types of inorganic solid electrolyte particles are not limited. Optionally, the inorganic solid electrolyte particles include, but are not limited to, one or more of oxide-based solid electrolyte particles, halide-based solid electrolyte particles, sulfide-based solid electrolyte particles, hydride-based solid electrolyte particles, and nitride-based solid electrolyte particles. It can be determined according to actual needs.

[0055] In the embodiments of the present disclosure, the two-dimensional layered powder includes a two-dimensional powder with a certain thickness composed of multiple lamellae, and there is a certain lamellar spacing between adjacent lamellae. At least part of the particles in the first inorganic solid electrolyte particles with a particle size in the range of 0.01 - 0.3 μm can be embedded into the interlayer and / or the surface of the lamellae of the two-dimensional layered powder. Moreover, the two-dimensional layered powder generally has surface defects on the two-dimensional lamellar surface, and these surface defects cooperate with the embedded inorganic solid electrolyte particles to construct a continuous lithium ion transport path, reduce the short circuit risk and capacity loss caused by lithium precipitation at the negative electrode side edge, and achieve the expected effect of filling the overhang void.

[0056] Optionally, the two-dimensional layered powder includes two-dimensional layered thermally conductive powder. The two-dimensional layered thermally conductive powder only needs to have a certain thermal conductivity, without limitation. In this embodiment, the use of the two-dimensional layered thermally conductive powder can enable the construction of a quasi-isotropic ion-conducting functional three-dimensional network with nano-scale inorganic solid electrolyte particles, increasing the thermal conductivity function, that is, constructing a quasi-isotropic dual-functional three-dimensional network of ion-conducting and heat-conducting, effectively reducing the heat concentration and ion transport hindrance inside the battery, and improving the safety and cycle life of the battery.

[0057] In some embodiments, the two-dimensional size of the two-dimensional layered powder is 0.8 - 2 μm. Optionally, the two-dimensional size of the two-dimensional layered powder is 1 - 1.5 μm.

[0058] Optionally, the powder particle thickness of the two-dimensional layered powder (or two-dimensional layered thermally conductive powder) is 0.7 - 20 nm. The thickness refers to the thickness of the powder particles of the two-dimensional layered powder in the direction perpendicular to the two-dimensional direction. The powder particles can be single-layer two-dimensional powder or multi-layer two-dimensional powder.

[0059] Optionally, the two-dimensional layered powder includes multi-layer two-dimensional powder (or multi-layer two-dimensional thermally conductive powder), and the thickness of the powder particles is 2 nm - 20 nm. Optionally, the thickness of the powder particles is 5 nm - 20 nm. Optionally, the thickness of the powder particles is 10 nm - 20 nm.

[0060] In some embodiments, the mass ratio of the inorganic solid electrolyte particles to the two-dimensional layered powder (defined as the first mass ratio) is 0.5 - 1.5:1. For example, the first mass ratio is 0.5:1, 0.8:1, 1:1, 1.2:1 or 1.5:1.

[0061] Optionally, the two-dimensional layered powder includes one or more of two-dimensional layered nitride inorganic materials, layered silicate materials, layered sulfides, and two-dimensional metal-organic frameworks. It can be determined according to the actual situation.

[0062] Optionally, the two-dimensional layered nitride inorganic material includes hexagonal boron nitride, two-dimensional layered aluminum nitride, or two-dimensional layered carbon nitride.

[0063] Optionally, the layered silicate material includes montmorillonite.

[0064] Optionally, the layered sulfide includes molybdenum disulfide or tungsten disulfide.

[0065] Optionally, the two-dimensional layered powder includes one or more of hexagonal boron nitride, two-dimensional layered aluminum nitride, two-dimensional layered carbon nitride, montmorillonite, MXene, molybdenum disulfide, tungsten disulfide, and two-dimensional metal-organic frameworks.

[0066] In the 3D printed overhang slurry according to the embodiments of the present disclosure, the binder is used to bond the composite powder. By controlling the ratio of the composite powder to the binder, the slurry can have rheological properties suitable for 3D printing methods, and the stability of the formed overhang encapsulation structure and the heat dissipation and ion transport functions can be ensured. Therefore, it is sufficient to control the mass ratio of the composite powder to the binder to be (4-20):1.

[0067] Optionally, the mass ratio of the composite powder to the binder is (4-18):1. Optionally, the mass ratio of the composite powder to the binder is (5-15):1. Optionally, the mass ratio of the composite powder to the binder is (8-12):1. Optionally, the mass ratio of the composite powder to the binder is (9-10):1.

[0068] In some embodiments, the binder includes, but is not limited to, one or more of polyvinylidene fluoride, nitrile rubber, butadiene rubber, styrene-butadiene rubber, polypropylene carbonate, poly-tert-butyl acrylate, polyethylene glycol diacrylate, polyethylene oxide, polyethylene-methyl methacrylate, polymethyl methacrylate, polyethylene glycol diacrylate, polyacrylonitrile, polyisobutene, ethylene vinyl acetate and its derivatives.

[0069] In the 3D printed overhang slurry according to the embodiments of the present disclosure, the surfactant can reduce the interfacial tension between the slurry and the printing substrate (for example, the empty foil area of the positive electrode tab or the overhang area of the negative electrode tab) and the side (or end face) of the electrode, improve the wettability of the slurry, increase the adhesion strength between the overhang and the side (or end face) of the electrode and between layers, enhance the stability of the overhang encapsulation structure. At the same time, the surfactant can form a self-assembled lubricating layer on the surface of the inorganic solid electrolyte particles and two-dimensional layered powder (or two-dimensional layered heat-conducting powder), reduce the friction between particles, and improve the dispersion uniformity and rheological properties of the slurry. It is necessary to control the proportion of the surfactant in the slurry. For example, the mass ratio of the surfactant to the binder is (0.0005-0.02):1. The proportion of the surfactant in the slurry should not be too large, otherwise it is easy to make the fluidity of the slurry too large and thus difficult to maintain the shape fidelity of the printed structure. In addition, bubbles are likely to be generated in the slurry, affecting the density of printing and the strength after forming.

[0070] Optionally, the mass ratio of the surfactant to the binder is 0.001-0.02:1. Optionally, the mass ratio of the surfactant to the binder is 0.005-0.02:1. Optionally, the mass ratio of the surfactant to the binder is 0.01-0.02:1.

[0071] Optionally, the mass ratio of the surfactant to the binder is 0.005:1, 0.008:1, 0.01:1, 0.015:1, 0.02:1.

[0072] Optionally, the surfactant includes one or more of linear alkyl primary thiol, polyethylene glycol octyl phenyl ether, polysorbate - 20, sorbitan monooleate, oleic acid, stearic acid, and hydroxy - functionalized alkyl ammonium salt.

[0073] In some embodiments, the 3D - printed overhang slurry of the embodiments of the present disclosure further includes: a lithium salt; the mass ratio of the lithium salt to the binder is 0.05 - 0.15:1. In this embodiment, by adding a lithium salt as a supplementary lithium source in the overhang encapsulation structure to provide sufficient lithium ions, and cooperating with the interfaces of the binder, inorganic solid - state electrolyte particles, and two - dimensional layered material (or two - dimensional layered thermal conductive powder) to construct a continuous three - dimensional ion transport network. By controlling the dosage of the lithium salt, an appropriate concentration of lithium ions can be provided to ensure the lithium - ion transport ability, and it will not affect the plasticity of the binder, ensuring the strength and stability of the overhang encapsulation structure.

[0074] Optionally, the mass ratio of the lithium salt to the binder is 0.08 - 0.12:1. Optionally, the mass ratio of the lithium salt to the binder is 0.1:1.

[0075] Optionally, the lithium salt includes one or more of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium difluoroborate oxalate, lithium bis(oxalato)borate, and lithium trifluoromethanesulfonate.

[0076] Combined Figure 2 As shown, the embodiments of the present disclosure provide a preparation method of a 3D - printed overhang slurry, including the following steps: S110. Prepare each raw material according to the 3D - printed overhang slurry of any one of the foregoing embodiments. In this step S110, each raw material at least includes inorganic solid - state electrolyte particles, two - dimensional layered powder, binder, surfactant, and solvent. Or, it further includes a lithium salt. The dosage of each raw material meets the dosage of each raw material of the 3D - printed overhang slurry of any one of the foregoing embodiments.

[0077] S120. Ball - mill and mix the inorganic solid - state electrolyte particles and the two - dimensional layered powder to obtain a composite powder; S130. Mix the composite powder with other raw materials to obtain a 3D - printed overhang slurry. In this embodiment, other raw materials at least include a binder, a surfactant, and a solvent; or, it further includes a lithium salt.

[0078] In the method of the embodiments of the present disclosure, inorganic solid electrolyte particles and two-dimensional layered powder are mixed evenly by ball milling to obtain a composite powder, and then the composite powder is mixed evenly with other raw materials. During the ball milling process, strong collisions and frictions between the inorganic solid electrolyte particles and the two-dimensional layered material (or two-dimensional layered thermal conductive powder) will further create abundant defects on the surface of the two-dimensional layered material, providing a large number of affinity sites for lithium ions. Moreover, under the action of the grinding shear force, the amount of inorganic solid electrolyte particles embedded between the layers and / or on the surface of the two-dimensional layered powder can be increased, thereby synergistically constructing a better continuous lithium ion transmission path and reducing the short circuit risk and capacity loss caused by lithium precipitation at the edge of the negative electrode side.

[0079] Optionally, in step S120, the ball milling parameters include: the ball-to-material ratio is 10-40:1; and / or, the rotation speed is 400-600 rpm; and / or, the ball milling time is 1-2 h.

[0080] Optionally, the ball-to-material ratio is 20-40:1.

[0081] In step S130, mixing the composite powder with other raw materials includes mixing the composite powder with other raw materials by stirring. In this embodiment, the stirring and mixing method is determined according to the actual situation.

[0082] The embodiments of the present disclosure provide an electrode tab, which can be a positive electrode tab or a negative electrode tab. When the electrode tab includes a positive electrode tab, the positive electrode tab includes an empty foil area, and a 3D printed overhang paste is provided in the empty foil area. When the electrode tab includes a negative electrode tab, the negative electrode tab includes an overhang area, and a 3D printed overhang paste is provided in the overhang area of the negative electrode tab. When the electrode tab includes a composite negative electrode tab with solid electrolyte layers provided on both its two side surfaces, a 3D printed overhang paste is provided on the surface of the solid electrolyte layer of the composite negative electrode tab corresponding to the overhang area of the negative electrode tab. Among them, the 3D printed overhang paste is the 3D printed overhang paste of any of the foregoing embodiments or the 3D printed overhang paste prepared by the preparation method of the 3D printed overhang paste of any of the foregoing embodiments.

[0083] A 3D printed overhang paste is provided in the area corresponding to the overhang area of the electrode tab of the embodiments of the present disclosure. For example, in the empty foil area of the positive electrode tab, on the surface of the overhang area of the negative electrode tab, or on the surface of the solid electrolyte layer of the composite negative electrode tab corresponding to the overhang area, so that the 3D printed overhang paste is provided in the overhang gap of the stacked battery cell, and an overhang encapsulation structure is obtained after curing.

[0084] The 3D printed overhang paste provided on the electrode tab in the embodiments of the present disclosure can be printed and provided by a 3D printing method.

[0085] The 3D printed overhang paste provided on the electrode tab in the embodiments of the present disclosure can enter the subsequent process while remaining in a paste state; or the 3D printed overhang paste can be cured and then enter the subsequent process, without limitation, which is determined according to the actual situation.

[0086] The embodiments of the present disclosure provide an electric core, including a positive electrode tab and a negative electrode tab stacked alternately, and a solid electrolyte layer is provided between adjacent positive electrode tabs and negative electrode tabs; at least one side of the negative electrode tab in the circumferential direction extends beyond the positive electrode tab to form an overhang region; wherein, a packaging structure is provided in the overhanging void region corresponding to the overhang region; wherein, the packaging structure is obtained by disposing the 3D printed overhang paste in the overhanging void region; the 3D printed overhang paste is the 3D printed overhang paste of any of the foregoing embodiments or the 3D printed overhang paste prepared by the preparation method of the 3D printed overhang paste of any of the foregoing embodiments.

[0087] The electric core in the embodiments of the present disclosure includes the 3D printed overhang paste of any of the foregoing embodiments, and the electric core has all the technical effects of the 3D printed overhang paste, which will not be elaborated herein.

[0088] In the electric core of the embodiments of the present disclosure, the 3D printed overhang paste will be cured to obtain a packaging structure. Curing is a process of evaporating the solvent in the paste. Therefore, the curing temperature is determined according to the type of solvent used. Optionally, the temperature is 60°C to 150°C.

[0089] In some embodiments, the positive electrode tab adopts the positive electrode tab in the electrode tab of any of the foregoing embodiments; or, the negative electrode tab adopts the negative electrode tab or the combined negative electrode tab in the electrode tab of any of the foregoing embodiments.

[0090] Combined Figure 3 As shown, the embodiments of the present disclosure provide a method for manufacturing an electric core, including the following steps: S210. Prepare a positive electrode tab, a negative electrode tab and a solid electrolyte layer; wherein, the size of the negative electrode tab is at least larger than that of the positive electrode tab on at least one side in the circumferential direction, so that the negative electrode tab has an overhang region; wherein, the positive electrode tab adopts the positive electrode tab of any of the foregoing embodiments, or the negative electrode tab adopts the negative electrode tab or the combined negative electrode tab of any of the foregoing embodiments.

[0091] S220. Alternately stack the positive electrode sheet and the negative electrode sheet, and dispose a solid electrolyte layer between adjacent positive and negative electrode sheets to obtain an electric core; wherein, a cured 3D printed overhang paste is disposed at the overhang gap of the electric core.

[0092] Optionally, in step S210, preparing the positive electrode sheet includes: disposing a positive electrode active paste on a positive electrode current collector to obtain a positive electrode active material layer, and leaving an empty foil area on the positive electrode current collector around the positive electrode active material layer; printing and disposing the 3D printed overhang paste on the empty foil area of the positive electrode sheet by a 3D printing method to obtain the positive electrode sheet.

[0093] Optionally, in step S210, preparing the negative electrode sheet includes: disposing a negative electrode active paste on a negative electrode current collector to obtain a negative electrode active material layer, and obtaining it by printing and disposing the 3D printed overhang paste on the surface of the negative electrode sheet in the overhang area of the negative electrode sheet by a 3D printing method.

[0094] Optionally, in step S210, it further includes: transferring the solid electrolyte layer to both surfaces of the negative electrode sheet, and printing and disposing the 3D printed overhang paste on the surface of the solid electrolyte layer corresponding to the overhang area of the negative electrode sheet by a 3D printing method to obtain a combined negative electrode sheet.

[0095] Optionally, before alternately stacking the positive electrode sheet and the negative electrode sheet in step S220, it further includes: curing the 3D printed overhang paste disposed on the positive electrode sheet or the negative electrode sheet to obtain a positive electrode sheet or a negative electrode sheet with a packaging structure. Or, after alternately stacking the positive electrode sheet and the negative electrode sheet in step S220, it further includes: curing the stacked sheet electric core structure to obtain an electric core with a packaging structure. Determine according to the actual situation.

[0096] The embodiments of the present disclosure further provide a solid-state battery, including: the electrode sheets of any one of the foregoing embodiments; or, the electric cores of any one of the foregoing embodiments; or the electric cores prepared by the preparation method of the electric cores of any one of the foregoing embodiments.

[0097] Specific embodiments are given below to specifically illustrate the 3D printed overhang paste, electrode sheets, electric cores, and their preparation methods and solid-state batteries of the embodiments of the present disclosure, so as to more clearly illustrate the technical problems, technical solutions, and beneficial effects solved by the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The description of at least one exemplary embodiment below is actually only illustrative and in no way limits the present application and its application.

[0098] In the examples where specific technologies or conditions are not specified, follow the technologies or conditions described in the literature in this field or according to the product instructions. For reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchases.

[0099] Example 1 A 3D printing overhang slurry, comprising composite powder, binder, lithium salt, surfactant and solvent. The mass ratio of the composite powder to the binder is 4 - 20:1, the mass ratio of the surfactant to the binder is 0.0005 - 0.02:1, the mass ratio of the lithium salt to the binder is 0.05 - 0.15:1, and the solid content of the overhang slurry is 60% - 75%; wherein, the composite powder includes inorganic solid electrolyte particles and two-dimensional layered powder, and the mass ratio of the inorganic solid electrolyte particles to the two-dimensional layered powder is 0.5 - 1.5:1. The particle size distribution range of the inorganic solid electrolyte particles is 0.01 - 2 μm, and the mass percentage of the first inorganic solid electrolyte particles with a particle size in the range of 0.01 - 0.3 μm is 25% - 50%; the mass percentage of the second inorganic solid electrolyte particles with a particle size in the range of 0.3 - 0.6 μm is 40% - 60%; the mass percentage of the third inorganic solid electrolyte particles with a particle size in the range of 0.6 - 2 μm is 0% - 20% and not zero. The particle size ratio of the third inorganic solid electrolyte particles to the second inorganic solid electrolyte particles is 1:0.25 - 0.6; the particle size ratio of the second inorganic solid electrolyte particles to the first inorganic solid electrolyte particles is 1:0.03 - 0.4.

[0100] The two-dimensional size of the two-dimensional layered powder is 0.6 - 2 μm; some of the inorganic solid electrolyte particles are embedded into the interlayer and / or the surface of the lamellae of the two-dimensional layered powder.

[0101] The 3D printing overhang slurry of this Example 1 is defined as a three-stage compounded inorganic solid electrolyte particle.

[0102] In this Example 1, 4 kinds of slurries with specific compositions are given. Among them, the inorganic solid electrolyte particles are LATP oxide solid electrolytes, the binder is graft-modified polyvinylidene fluoride, the lithium salt is lithium bis(trifluoromethanesulfonyl)imide, the surfactant is polyoxyethylene octyl phenyl ether, and the solvent is low-boiling tetrahydrofuran. Among them, the mass ratio of the composite powder, binder, lithium salt, surfactant and solvent is 90:10:1:0.2:43 in sequence, and the solid content of the overhang slurry is 60% - 65%. The composition of the remaining raw materials is shown in Table 1.

[0103] Table 1

[0104] The preparation method of the 3D printing overhang slurry in Example 1 includes the following steps: For the 3D printing overhang slurry according to Example 1, prepare each raw material: inorganic solid electrolyte particles, two-dimensional layered powder, binder, lithium salt, surfactant, and solvent.

[0105] High-energy ball mill and mix the inorganic solid electrolyte particles and the two-dimensional layered powder to obtain a composite powder; among them, the high-energy ball milling parameters include: the ball-to-material ratio is 40:1; the rotation speed is 500 rpm; the ball milling time is 1.5 h.

[0106] Mix the composite powder, binder, lithium salt, surfactant, and solvent to obtain a 3D printing overhang slurry.

[0107] In Example 1, the rheological properties of the 3D printing overhang slurry were tested. As Figure 4 can be seen from the rheological property curve of the 3D printing overhang slurry shown, the viscosity of the 3D printing overhang slurry (Slurry I and Slurry II) in Example 1 is 2 - 10 Pa·s -1 . The viscosity is low and the rheological property is good.

[0108] Example 2 A 3D printing overhang slurry, including composite powder, binder, lithium salt, surfactant, and solvent. The mass ratio of the composite powder to the binder is 4 - 20:1, the mass ratio of the surfactant to the binder is 0.0005 - 0.02:1, the mass ratio of the lithium salt to the binder is 0.05 - 0.15:1, and the solid content of the overhang slurry is 60% - 75%; among them, the composite powder includes inorganic solid electrolyte particles and two-dimensional layered powder, and the mass ratio of the inorganic solid electrolyte particles to the two-dimensional layered powder is 0.5 - 1.5:1. The particle size distribution range of the inorganic solid electrolyte particles is 0.01 - 0.6 μm, and the mass percentage of the first inorganic solid electrolyte particles with a particle size in the range of 0.01 - 0.3 μm is 25% - 50%; the mass percentage of the second inorganic solid electrolyte particles with a particle size in the range of 0.3 - 0.6 μm is 50% - 75%. The particle size ratio of the second inorganic solid electrolyte particles to the first inorganic solid electrolyte particles is 1:0.03 - 0.4. The two-dimensional size of the two-dimensional layered powder is 0.6 - 2 μm; some inorganic solid electrolyte particles are embedded between the layers and / or on the surface of the lamellae of the two-dimensional layered powder.

[0109] The 3D printing overhang slurry in Example 2 is defined as two-stage compounded inorganic solid electrolyte particles.

[0110] In Example 2, a specific composition of Slurry V is given. The difference between Slurry V and Slurry I is that the inorganic solid electrolyte particles only include first inorganic solid electrolyte particles with a particle size of 0.01 μm and a mass percentage of 40%, and second inorganic solid electrolyte particles with a particle size of 0.3 μm and a mass percentage of 60%. The remaining raw materials, dosages, and preparation methods are the same as those of Slurry I.

[0111] Comparative Example 1 The Slurry Comparison I of this Comparative Example 1 is different from Slurry I in Example 1. In the preparation method, the inorganic solid electrolyte particles and the two-dimensional layered powder are mixed by mechanical stirring, and the stirring speed is 500 rpm. The remaining raw materials, compositions, and preparation methods are the same as those of Slurry I.

[0112] Comparative Example 2 The Slurry Comparison II of this Comparative Example 1 is different from Slurry I in Example 1. The surfactant is removed. The remaining raw materials, compositions, and preparation methods are the same as those of Slurry I.

[0113] The rheological property curve of the Slurry Comparison II of this Comparative Example 2 is as Figure 4 shown. It can be seen that compared with Slurry I of Example 1, the rheological property of the Slurry Comparison II without adding surfactant is significantly worse. This is because the surfactant can form a self-assembled lubricating layer on the surfaces of the inorganic solid electrolyte particles and the two-dimensional layered heat-conducting powder, reducing the friction between particles and improving the rheological property of the slurry.

[0114] Comparative Example 3 The Slurry Comparison III of this Comparative Example 3 is different from Slurry I in Example 1. The raw materials do not contain two-dimensional layered powder, that is, the proportion of the two-dimensional layered powder in the composite powder is 0. The remaining raw materials, compositions, and preparation methods are the same as those of Slurry I.

[0115] The rheological property curve of the Slurry Comparison III of this Comparative Example 3 is as Figure 4 shown. It can be seen that the viscosity of the Slurry Comparison III without adding two-dimensional material is greater and the processing property is worse. The reason is that: the slurry of Example 1 is compounded with two-dimensional material and solid electrolyte particles with multi-particle size distribution. Under shear force, the two-dimensional material acts as a lubricant, effectively reducing the movement resistance of the solid powder in the slurry. And the solid electrolyte particles with multi-particle size distribution enable the small-size solid electrolyte particles to flow in the gaps between the large-size solid electrolyte particles, weakening the flow resistance between particles, and further playing a role in reducing the viscosity of the slurry and improving the rheological property of the slurry.

[0116] Comparative Example 4 The slurry comparison Ⅳ of Comparative Example 4 is different from the slurry comparison Ⅲ of Comparative Example 3 in that the inorganic solid electrolyte particles are composed only of a single LATP oxide solid electrolyte with a particle size of 0.5 μm. The remaining raw materials, composition and preparation method are the same as those of the slurry comparison Ⅲ.

[0117] The rheological property curve of the slurry comparison Ⅳ of Comparative Example 4 is as Figure 4 shown. It can be seen that the viscosity of the slurry comparison Ⅳ without adding two-dimensional materials and without multi-particle size compounding is greater and the processing performance is worse. The reason is that: the slurry of Example 1 is compounded with two-dimensional materials and solid electrolyte particles with multi-particle size matching. Under shear force, the two-dimensional materials play the role of lubricant, effectively reducing the movement resistance of the solid powder in the slurry. And the solid electrolyte particles with multi-particle size matching enable the small particle size solid electrolyte particles to flow in the gaps between the large particle size solid electrolyte particles, weakening the flow resistance between the particles, further playing the role of reducing the slurry viscosity and improving the rheological properties of the slurry. Example 3 A positive electrode sheet, the positive electrode sheet includes an empty foil area, and an overhang encapsulation structure is provided in the empty foil area. The overhang encapsulation structure is obtained by curing the 3D printing overhang slurry printed to the empty foil area by a 3D printing method.

[0118] In this Example 3, the slurries Ⅰ to Ⅴ of Example 1 and Example 2 are respectively used as the 3D printing overhang slurries and printed to the empty foil area and then cured to obtain the positive electrode sheets Ⅰ to Ⅴ correspondingly. At the same time, the slurry comparisons Ⅰ to Ⅳ of Comparative Example 1 to Comparative Example 4 are respectively used as the 3D printing overhang slurries and printed to the empty foil area and then cured to obtain the positive electrode sheet comparisons Ⅰ to Ⅳ correspondingly.

[0119] In this Example 3, for subsequent solid-state battery assembly and battery performance testing, the following positive electrode sheets are specifically prepared.

[0120] The positive electrode sheet includes a positive electrode current collector (for example, an aluminum foil current collector) and a positive electrode active material layer provided on the positive electrode current collector. Specifically, the positive electrode slurry is coated on the positive electrode current collector, dried in a forced-air oven at 70 °C for 2 h and then transferred to a vacuum oven at 60 °C and dried for at least 6 h. The obtained dried electrode sheet is roll-pressed and then cut into a suitable size to obtain a semi-finished positive electrode sheet with an empty foil area reserved around the positive electrode active material layer, and stored in a vacuum oven. Among them, the positive electrode slurry is obtained by uniformly dispersing a graft-modified polyvinylidene fluoride binder, Super P, LATP solid electrolyte and NCM811 active material in a mass ratio of 1:1:10:88 in an N-methylpyrrolidone solvent.

[0121] Using a 3D printing method, print the 3D printing overhang slurry onto the empty foil area of the semi-finished positive electrode sheet. The printing width is 0.5 mm, and the thickness is the same as that of the semi-finished positive electrode sheet. After drying and curing, a positive electrode sheet with an overhang encapsulation structure is obtained.

[0122] Example 4 A battery cell includes alternately stacked positive electrode sheets and negative electrode sheets, and a solid electrolyte layer is provided between adjacent positive electrode sheets and negative electrode sheets; at least one side of the negative electrode sheet extends beyond the positive electrode sheet in the circumferential direction to form an overhang area; among them, an encapsulation structure is provided in the overhanging void area corresponding to the overhang area.

[0123] In this Example 4, the positive electrode sheets of Example 3, namely positive electrode sheet I to positive electrode sheet V, are respectively used for the positive electrode sheets, and battery cells I to battery cells V are correspondingly obtained. At the same time, positive electrode sheets for comparison I to positive electrode sheets for comparison IV are respectively used, and battery cells for comparison I to battery cells for comparison IV are correspondingly obtained.

[0124] In this Example 4, for subsequent solid-state battery assembly and battery performance testing, a lithium indium alloy with a silver-carbon protective layer is specifically selected as the negative electrode sheet, and a Li6PS5Cl solid electrolyte membrane prepared using PTFE as a binder is used as the solid electrolyte layer.

[0125] Example 5 A solid-state battery includes a battery cell.

[0126] In this Example 5, the battery cell is assembled into a solid-state battery, including: isostatic pressing, tab welding, and final encapsulation. Among them, the isostatic pressing parameters in the assembly process are 500 MPa and 15 min, and the rest of the assembly processes can be carried out using conventional operations.

[0127] In this Example 5, battery cells I to battery cells V of Example 4 are respectively assembled into solid-state batteries I to solid-state batteries V. At the same time, battery cells for comparison I to battery cells for comparison IV are respectively assembled into solid-state batteries for comparison I to solid-state batteries for comparison IV.

[0128] Comparative Example 5 In this Comparative Example 5, different from Example 5, the battery cell uses a stacked battery cell without overhang encapsulation, that is, the semi-finished positive electrode sheet in Example 3 is used for the positive electrode sheet, and solid-state battery for comparison V is obtained.

[0129] Performance test: 1. Test on the rheological properties of the 3D printed overhang slurry: The rheological properties of the slurry are tested using a rheometer at room temperature. A 40 mm flat plate fixture is used, the test gap is 150 µm, and the shear rate scanning mode is used. As Figure 4Rheological property curves of various slurries shown

[0130] 2. Test the rheological properties of Slurry I to Slurry V in Examples 1 and 2 and Slurry Comparison I to Slurry Comparison IV in Comparative Examples 1 to 4 during the actual 3D printing process. Under the conditions of a 3D printing needle aperture of 100 μm, a constant extrusion pressure of 0.3 MPa, a linear trajectory for path planning, a line width of 80 μm, a layer height of 20 μm, and a printing speed of 25 mm / s, test the continuous printing time of Slurry I to Slurry V and Slurry Comparison I to Slurry Comparison IV without clogging the needle and the number of times of needle clogging within 10 h. The test results are shown in Table 2.

[0131] Table 2

[0132] As can be seen from Table 2, Slurry I to Slurry V have a longer continuous printing time and fewer clogging times within 10 h compared to Slurry Comparison I to Slurry Comparison IV, indicating that by combining two-dimensional layered materials with inorganic solid electrolytes of multi-particle size compounding and adding a self-assembled lubricating layer formed by a surfactant on the powder surface, the rheological properties of the slurry can be significantly improved, and the feasibility and printing efficiency of 3D printing can be enhanced.

[0133] 3. Solid-state battery performance test: Perform initial short-circuit rate and cycle performance tests on Solid-state Battery I to Solid-state Battery V in Example 5 and Solid-state Battery Comparison I to Solid-state Battery Comparison IV respectively.

[0134] The short-circuit rate is tested using a multimeter. The test results are shown in Table 3. Compared with Comparative Example 5 without Overhang design, the short-circuit rates of the corresponding solid-state batteries in Examples 1-5 and Comparative Examples 1-4 with Overhang design are significantly reduced, and the short-circuit rate of the solid-state batteries in Examples 1-5 prepared with 3D printing Overhang slurry with two-dimensional materials and solid electrolyte particles of different particle sizes is 0%. It shows that the Overhang prepared from the 3D printing Overhang slurry of the present application can significantly alleviate the short-circuit problem in solid-state batteries and improve the yield and safety of solid-state batteries.

[0135] Table 3

[0136] The cycle performance test is carried out using a charge-discharge test cabinet. Assemble a mold battery, set the voltage range to 2.8 V to 4.3 V, and perform charge-discharge cycle tests with a charge-discharge current of 0.1 C, and record process data such as the charge-discharge gram capacity of the battery. The test results are shown in Table 4.

[0137] Table 4

[0138] As can be seen from the data in Table 4, compared with Solid State Battery Comparison I to Solid State Battery Comparison V, the capacity retention rate of the solid state batteries of Solid State Battery I to Solid State Battery V after 100 cycles is significantly higher and the short circuit rate is relatively lower, indicating the beneficial effect of the Overhang design of the present application on alleviating the short circuit of solid state batteries and improving the battery cycle performance. Solid State Battery I to Solid State Battery V all use 3D printed Overhang slurries of two-dimensional material composite multi-sized solid electrolyte particles, which have more excellent rheological properties, better 3D printing processability, the obtained Overhang has higher density and strength, and stronger ability to inhibit edge curling and lithium dendrites; in addition, the synergistic effect generated by the two-dimensional material and the solid electrolyte particles after high-energy ball milling can construct a continuous lithium ion transport path in the Overhang, evenly deposit lithium ions at the negative electrode edge, which is beneficial to inhibiting the growth of lithium dendrites and further improving the cycle life and safety of the battery.

[0139] In the embodiments of the present disclosure, for the inorganic solid electrolyte particles, when the endpoint values of the particle size ranges of the first inorganic solid electrolyte particles, the second inorganic solid electrolyte particles, and the third inorganic solid electrolyte particles coincide, it is default that the maximum endpoint value particle size of the particle size range may not be included, or the minimum endpoint value particle size of the particle size range may not be included, as long as the overlapping particle size values are avoided.

[0140] The above description and the accompanying drawings fully illustrate the embodiments of the present disclosure, enabling those skilled in the art to practice them. Other embodiments may include structural, logical, electrical, process, and other changes. The embodiments merely represent possible variations. Unless explicitly required, the individual components and functions are optional, and the order of operations may vary. Parts and features of some embodiments may be included in or replace parts and features of other embodiments. Moreover, the terms used in this application are only for describing the embodiments and do not limit the claims. As used in the description of the embodiments and the claims, unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" are intended to also include the plural forms. Similarly, as used in this application, the term "and / or" refers to any and all possible combinations of one or more of the associated listed items. Additionally, when used in this application, the term "comprise" and its variants "comprises" and / or "comprising" etc. mean the presence of the stated features, wholes, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or groups of these. Without further limitation, an element defined by the statement "comprising one..." does not exclude the presence of another identical element in the process, method, or device comprising the element. In this article, what each embodiment focuses on may be the differences from other embodiments, and the same or similar parts between the embodiments may be referred to each other. For the methods, products, etc. disclosed in the embodiments, if they correspond to the method parts disclosed in the embodiments, the relevant parts may refer to the description of the method parts.

[0141] Those skilled in the art can realize that the units and steps of each example described in combination with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are executed in a hardware or software manner may depend on the specific application and design constraints of the technical solution. The skilled person may use different methods for each specific application to implement the described functions, but such implementation should not be considered to exceed the scope of the embodiments of the present disclosure. The skilled person can clearly understand that for the convenience and brevity of description, the specific working processes of the systems, devices, and units described above can refer to the corresponding processes in the foregoing method embodiments, and will not be elaborated herein.

[0142] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to embodiments of the present disclosure. In this regard, each block in the flowchart or block diagram may represent a module, a segment of a program, or a portion of code, which contains one or more executable instructions for implementing a specified logical function. In some alternative implementations, the functions noted in the blocks may occur in a different order than noted in the accompanying drawings. For example, two consecutive blocks may in fact be executed substantially in parallel, or they may sometimes be executed in the reverse order, depending on the functions involved. In the description corresponding to the flowcharts and block diagrams in the accompanying drawings, the operations or steps corresponding to different blocks may also occur in a different order than disclosed in the description, and sometimes there is no specific order between different operations or steps. For example, two consecutive operations or steps may in fact be executed substantially in parallel, or they may sometimes be executed in the reverse order, depending on the functions involved. Each block in the block diagram and / or flowchart, and combinations of blocks in the block diagram and / or flowchart, may be implemented by a dedicated hardware-based system that performs the specified functions or actions, or may be implemented by a combination of dedicated hardware and computer instructions.

Claims

1. A 3D printing overhang slurry, characterized in that, Comprising: Composite powder, binder, surfactant and solvent, the mass ratio of the composite powder to the binder is 4 - 20:1, the mass ratio of the surfactant to the binder is 0.0005 - 0.02:1, and the solid content of the overhang slurry is 60% - 75%; wherein, the composite powder includes inorganic solid electrolyte particles and two-dimensional layered powder, and the mass ratio of the inorganic solid electrolyte particles to the two-dimensional layered powder is 0.5 - 1.5:1, the particle size distribution range of the inorganic solid electrolyte particles is 0.01 - 2 μm, and the mass percentage of the first inorganic solid electrolyte particles with a particle size in the range of 0.01 - 0.3 μm is 25% - 50%; the two-dimensional size of the two-dimensional layered powder is 0.6 - 2 μm; part of the inorganic solid electrolyte particles are embedded into the interlayer and / or the surface of the sheet layer of the two-dimensional layered powder.

2. The 3D printing overhang slurry according to claim 1, wherein in the inorganic solid electrolyte particles, the mass percentage of the second inorganic solid electrolyte particles with a particle size in the range of 0.3 - 0.6 μm is 40% - 75%; and / or in the inorganic solid electrolyte particles, the mass percentage of the third inorganic solid electrolyte particles with a particle size in the range of 0.6 - 2 μm is 0% - 20%; when the mass percentage of the third inorganic solid electrolyte particles is not 0, the inorganic solid electrolyte particles include the first inorganic solid electrolyte particles, the second inorganic solid electrolyte particles and the third inorganic solid electrolyte particles, and the sum of the mass percentages is 100%.

3. The 3D printing overhang slurry according to claim 2, wherein the particle size ratio of the second inorganic solid electrolyte particles with a particle size in the range of 0.3 - 0.6 μm to the first inorganic solid electrolyte particles is 1:0.03 - 0.4; and / or the particle size ratio of the third inorganic solid electrolyte particles with a particle size in the range of 0.6 - 2 μm to the second inorganic solid electrolyte particles with a particle size in the range of 0.3 - 0.6 μm is 1:0.25 - 0.6; and / or the mass ratio of the second inorganic solid electrolyte particles with a particle size in the range of 0.3 - 0.6 μm to the first inorganic solid electrolyte particles is 4 - 7:3 - 6; and / or the mass ratio of the third inorganic solid electrolyte particles with a particle size in the range of 0.6 - 2 μm, the second inorganic solid electrolyte particles with a particle size in the range of 0.3 - 0.6 μm and the first inorganic solid electrolyte particles is 0 - 2:4 - 7:3 - 6; and the third inorganic solid electrolyte particles are not 0.

4. The 3D printing overhang slurry according to claim 1, wherein the inorganic solid electrolyte particles include one or more of oxide-based solid electrolyte particles, halide-based solid electrolyte particles, sulfide-based solid electrolyte particles, hydride-based solid electrolyte particles and nitride-based solid electrolyte particles; and / or, the two-dimensional layered powder includes two-dimensional layered heat-conducting powder; and / or The two-dimensional layered powder includes one or more of nitride inorganic materials, layered silicate materials, layered sulfides, and two-dimensional metal-organic frameworks in a two-dimensional layered form; and / or, The two-dimensional layered powder includes one or more of hexagonal boron nitride, two-dimensional layered aluminum nitride, two-dimensional layered carbon nitride, montmorillonite, MXene, molybdenum disulfide, tungsten disulfide, and two-dimensional metal-organic frameworks; and / or The binder includes one or more of polyvinylidene fluoride, nitrile rubber, butadiene rubber, styrene-butadiene rubber, polypropylene carbonate, poly-tert-butyl acrylate, polyethylene glycol diacrylate, polyethylene oxide, polyethylene-methyl methacrylate, polymethyl methacrylate, polyethylene glycol diacrylate, polyacrylonitrile, polyisobutene, and polyethylene vinyl acetate and its derivatives; and / or The solvent includes one or more of N,N-dimethylacetamide, N-methylpyrrolidone, acetonitrile, toluene, xylene, butyl butyrate, isobutyl butyrate, ethyl acetate, chloroform, tetrahydrofuran, and alkanes; and / or The surfactant includes one or more of linear alkyl primary thiol, polyethylene glycol octyl phenyl ether, polysorbate-20, sorbitan monooleate, oleic acid, stearic acid, and hydroxy-functionalized alkyl ammonium salts.

5. The 3D printing overhang paste according to any one of claims 1 to 4, characterized in that It further includes: A lithium salt; the mass ratio of the lithium salt to the binder is 0.05 - 0.15:

1.

6. The 3D printing overhang slurry according to claim 5, wherein The mass ratio of the lithium salt to the binder is 0.08 - 0.12:1; or, the mass ratio of the lithium salt to the binder is 0.1:1; and / or The lithium salt includes one or more of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium oxalodifluoroborate, lithium bis(oxalato)borate, and lithium trifluoromethanesulfonate.

7. The 3D printing overhang slurry according to any one of claims 1 to 4, wherein The mass ratio of the composite powder to the binder is 4 - 18:1; or, the mass ratio of the composite powder to the binder is 5 - 15:1; or, the mass ratio of the composite powder to the binder is 8 - 12:1; or, the mass ratio of the composite powder to the binder is 9 - 10:1; and / or The mass ratio of the surfactant to the binder is 0.001 - 0.02:1; or, the mass ratio of the surfactant to the binder is 0.005 - 0.02:1; or, the mass ratio of the surfactant to the binder is 0.01 - 0.02:

1.

8. The preparation method of the 3D printing overhang paste according to any one of claims 1 to 7, characterized in that It includes: Prepare each raw material according to the 3D printing overhang slurry according to any one of claims 1 to 7; Ball-mill and mix the inorganic solid electrolyte particles and the two-dimensional layered powder to obtain a composite powder; Mix the composite powder with other raw materials to obtain a 3D printing overhang slurry.

9. The preparation method according to claim 8, wherein The ball-milling parameters include: the ball-to-material ratio is 10 - 40:1; and / or, the rotation speed is 400 - 600 rpm; and / or, the ball-milling time is 1 - 2 h.

10. An electrode tab, characterized in that, The electrode pole piece is a positive electrode pole piece or a negative electrode pole piece; When the electrode sheet includes a positive electrode sheet, the positive electrode sheet includes an empty foil area, and a 3D printed overhang paste is provided in the empty foil area; When the electrode sheet includes a negative electrode sheet, the negative electrode sheet includes an overhang area, and a 3D printed overhang paste is provided in the overhang area of the negative electrode sheet; When the electrode sheet includes a negative electrode sheet and the negative electrode sheet is a composite negative electrode sheet provided with solid electrolyte layers on both of its side surfaces, a 3D printed overhang paste is provided on the surface of the solid electrolyte layer of the composite negative electrode sheet corresponding to the overhang area of the negative electrode sheet; Among them, the 3D printed overhang paste is the 3D printed overhang paste described in any one of claims 1 to 7 or the 3D printed overhang paste obtained by the preparation method of the 3D printed overhang paste described in any one of claims 8 to 9.

11. A battery cell, characterized in that, It includes alternately stacked positive electrode sheets and negative electrode sheets, and a solid electrolyte layer is provided between adjacent positive electrode sheets and negative electrode sheets; at least one side of the negative electrode sheet in the circumferential direction extends beyond the positive electrode sheet to form an overhang area; among them, a packaging structure is provided in the overhanging void area corresponding to the overhang area; Among them, the packaging structure is obtained by providing a 3D printed overhang paste in the overhanging void area; the 3D printed overhang paste is the 3D printed overhang paste described in any one of claims 1 to 7 or the 3D printed overhang paste obtained by the preparation method of the 3D printed overhang paste described in any one of claims 8 to 9.

12. The battery cell according to claim 11, characterized in that, The positive electrode sheet adopts the positive electrode sheet in the electrode sheet described in claim 10; or, the negative electrode sheet adopts the negative electrode sheet or the composite negative electrode sheet in the electrode sheet described in claim 10.

13. The method for preparing an electric core according to claim 11 or 12, characterized in that, It includes: Preparing a positive electrode sheet, a negative electrode sheet and a solid electrolyte layer; among them, the size of the negative electrode sheet is at least larger than that of the positive electrode sheet on one side in the circumferential direction, so that the negative electrode sheet has an overhang area; among them, the positive electrode sheet adopts the positive electrode sheet described in claim 10, or the negative electrode sheet adopts the negative electrode sheet or the composite negative electrode sheet described in claim 10; Alternately stacking the positive electrode sheet and the negative electrode sheet, and providing a solid electrolyte layer between adjacent positive electrode sheets and negative electrode sheets to obtain an electric core; Among them, a cured 3D printed overhang paste is provided at the overhang void of the electric core.

14. The method for preparing an electric core according to claim 13, wherein Before alternately stacking the positive electrode sheet and the negative electrode sheet, it further includes: curing the 3D printed overhang paste provided on the positive electrode sheet or the negative electrode sheet to obtain a positive electrode sheet or a negative electrode sheet with a packaging structure; or, After alternately stacking the positive electrode sheet and the negative electrode sheet, it further includes: curing the stacked laminated electric core structure to obtain an electric core with a packaging structure.

15. A solid-state battery, characterized in that, It includes: The electrode tab according to claim 10; or, the battery cell according to claim 11 or 12; or the battery cell obtained by the method for preparing a battery cell according to claim 13 or 14.

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