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

Abstract

The present application relates to the field of solid-state battery technology, and discloses a battery cell, which includes stacked positive and negative electrode sheets, and a solid electrolyte layer is provided between adjacent positive and negative electrode sheets, and at least one side of the negative electrode sheet extends beyond the positive electrode sheet to form an overhang area, and a packaging structure is provided in the overhanging gap area corresponding to the overhang area; wherein, the packaging structure includes a lithium supplement, the lithium supplement has ionic conductivity, and the lithium depolymerization product of the lithium supplement includes a solid product and lithium ions, and the solid product is electronically insulating. In this way, the insulating support function and the lithium supplement function can be effectively combined with the packaging structure. The lithium supplement in the packaging structure has the function of a lithium source, which can effectively improve the first coulomb efficiency of the battery and the energy density of the battery. At the same time, the solid product in the lithium depolymerization product of the lithium supplement is electronically insulating, and will not affect the electrochemical reaction path and stability inside the battery cell. The present application also discloses a preparation method, a 3D printed overhang slurry, and a solid-state battery.

Description

Technical Field

[0001] The present application relates to the field of solid-state battery technology, for example, to a battery cell and a preparation method thereof, a 3D printing overhang slurry and a solid-state battery. Background Art

[0002] As the energy sector continues to increase its requirements for battery energy density and safety, solid-state batteries, with their advantages such as high energy density and inherent safety, have become an important development direction for future battery technology. When a solid-state battery is first charged, a solid electrolyte interface (SEI) membrane forms, and lithium loss occurs in the positive electrode material. This reduces the number of lithium ions available for charge and discharge reactions in the battery, reducing the actual available capacity of the battery and, in turn, affecting the battery's energy density and cycle performance. To address this issue, those skilled in the art typically resort to lithium replenishment to compensate for the effects of lithium loss.

[0003] Currently, the common approach to addressing lithium loss in solid-state batteries is to layer a lithium-replenishing layer on the electrode surface. However, these lithium-replenishing methods introduce additional inactive materials, occupying the limited space within the battery cell and thus reducing the energy density of solid-state batteries.

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

[0005] In order to provide a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. The summary is not an extensive review, nor is it intended to identify key / critical 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 battery cell and a preparation method thereof, a 3D printed overhang slurry, and a solid-state battery to solve the problem of reduced battery energy density due to the introduction of inactive substances into the lithium replenishment layer during the lithium replenishment process of existing solid-state batteries.

[0007] In some embodiments, the battery cell includes: stacked positive electrode sheets and negative electrode sheets, and a solid electrolyte layer is arranged between adjacent positive electrode sheets and negative electrode sheets, at least one side of the negative electrode sheet extends beyond the positive electrode sheet to form an overhang area, and a packaging structure is arranged in the overhang gap area corresponding to the overhang area; wherein the packaging structure includes a lithium supplement agent, the lithium supplement agent has ionic conductivity, and the delithiation product of the lithium supplement agent includes a solid product and lithium ions, and the solid product is electronically insulating.

[0008] In some embodiments, the method for preparing the battery cell includes: preparing a positive electrode sheet, a negative electrode sheet and a solid electrolyte layer; wherein the size of the negative electrode sheet is larger than the size of the positive electrode sheet on at least one circumferential side, so that the negative electrode sheet has an overhang area; setting a packaging material on the circumferential side of the positive electrode sheet to obtain a positive electrode sheet with a packaging structure; or, setting a packaging material on the end face of the solid electrolyte layer facing the positive electrode sheet to obtain a solid electrolyte layer with a packaging structure; wherein the packaging material includes the aforementioned lithium supplement, and the packaging structure corresponds to the overhang area; and stacking the negative electrode sheet, the solid electrolyte layer and the positive electrode sheet in the order of the negative electrode sheet, the solid electrolyte layer and the positive electrode sheet to obtain a battery cell.

[0009] In some embodiments, the 3D printed overhang slurry is used as a packaging material for the aforementioned packaging structure of the battery cell, or as a packaging material in the aforementioned method for preparing the battery cell; in terms of mass percentage, the 3D printed overhang slurry includes: 10% to 50% of a lithium supplement agent, 1% to 30% of a second binder, and 2% to 89% of a solvent; wherein the lithium supplement agent has ionic conductivity, the delithiation product of the lithium supplement agent includes a solid product and lithium ions, and the solid product is electronically insulating.

[0010] In some embodiments, the solid-state battery includes: the aforementioned battery cell; or a battery cell obtained using the aforementioned battery cell preparation method.

[0011] The battery cell and its preparation method, 3D printing overhang slurry, and solid-state battery provided in the embodiments of the present disclosure can achieve the following technical effects:

[0012] The battery cell provided by the embodiment of the present disclosure can effectively combine the insulating support function and the lithium replenishment function in the packaging structure by forming an overhang area on at least one side of the circumference of the negative electrode sheet exceeding the positive electrode sheet, and providing a packaging structure including a lithium replenisher in the overhang gap area corresponding to the overhang area. The lithium replenisher in the packaging structure has the function of a lithium source, and can effectively release lithium ions during the battery charging process, compensate for the lithium loss caused by factors such as the formation of the SEI film, thereby effectively improving the battery's first coulombic efficiency and the battery's energy density. At the same time, the solid product in the delithiation product of the lithium replenisher is electronically insulating and will not affect the electrochemical reaction path and stability inside the battery cell. In this way, the overhang gap area can be fully utilized to achieve the lithium replenishment function without reducing the battery's energy density. The packaging structure can also form a stable support for the overhang area, effectively preventing short circuit problems caused by the misalignment of the positive and negative electrode sheets during assembly.

[0013] In the cell manufacturing method of the disclosed embodiments, packaging material is applied to the circumferential side surfaces of the positive electrode sheet or the end surface of the solid electrolyte layer facing the positive electrode sheet, corresponding to the overhang area. Through a molding process, a composite packaging structure with both lithium replenishment and short-circuit protection is constructed. This method integrates the release of the lithium replenisher and the insulation protection functions into the packaging structure, avoiding the stacking of multiple functional structures such as lithium replenishment layers and insulation layers in traditional solutions. This simplifies the process and improves production efficiency.

[0014] The above general description and the following description are exemplary and explanatory only and are not intended to limit the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] One or more embodiments are exemplarily described by corresponding drawings. These exemplary descriptions and drawings do not limit the embodiments. Elements with the same reference numerals in the drawings are shown as similar elements. The drawings do not constitute a scale limitation. In addition,

[0016] Figure 1 is a structural schematic diagram of a battery cell provided by an embodiment of the present disclosure;

[0017] Figure 2 is a schematic structural diagram of another battery cell provided by an embodiment of the present disclosure;

[0018] Figure 3 is a schematic structural diagram of another battery cell provided by an embodiment of the present disclosure;

[0019] Figure 4 is a schematic structural diagram of another battery cell provided by an embodiment of the present disclosure;

[0020] Figure 5 is a schematic structural diagram of another battery cell provided by an embodiment of the present disclosure;

[0021] Figure 6 is a schematic structural diagram of another battery cell provided by an embodiment of the present disclosure;

[0022] Figure 7 This is a schematic diagram of the structure of a battery cell provided in Comparative Example 3;

[0023] Figure 8 It is a schematic flow chart of a method for preparing a battery cell provided by an embodiment of the present disclosure;

[0024] Figure 9 It is a flow chart of another method for preparing a battery cell provided in an embodiment of the present disclosure.

[0025] Reference numerals:

[0026] 101: Tab; 102: Packaging structure; 1021: Embedding groove; 103: Positive electrode active material layer; 104: Positive electrode current collector layer; 105: Solid electrolyte layer; 106: Positive electrode sheet; 16: Positive electrode lithium replenishing coating. DETAILED DESCRIPTION

[0027] In order to be able to understand the features and technical content of the embodiments of the present disclosure in more detail, the implementation of the embodiments of the present disclosure is described in detail below in conjunction with the accompanying drawings. The accompanying drawings are for reference only and are not used to limit the embodiments of the present disclosure. In the following technical description, for the sake of convenience of explanation, a full understanding of the disclosed embodiments is provided through multiple details. However, one or more embodiments can still be implemented without these details. In other cases, to simplify the drawings, well-known structures and devices can be simplified for display.

[0028] In the description and claims of the embodiments of the present disclosure, as well as in the accompanying drawings, the terms "first," "second," and the like are used to distinguish similar objects and are not necessarily used to describe a particular order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate to facilitate understanding of the embodiments of the present disclosure described herein. In addition, the terms "including," "having," and any variations thereof are intended to cover non-exclusive inclusions.

[0029] In the embodiments of the present disclosure, the terms "upper", "lower", "inside", "middle", "outside", "front", "back" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. These terms are mainly intended to better describe the embodiments of the present disclosure and their embodiments, and are not intended to limit the indicated devices, elements or components to having a specific direction, or to be constructed and operated in a specific direction. Moreover, in addition to being used to indicate directions or positional relationships, some of the above terms may also be used to indicate other meanings. For example, the term "upper" may also be used to indicate a certain dependency or connection relationship in certain circumstances. 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.

[0030] Furthermore, the terms "disposed," "connected," and "fixed" should be interpreted broadly. For example, "connected" can mean a fixed connection, a removable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection, an indirect connection through an intermediary, or an internal connection between two devices, elements, or components. Those skilled in the art will understand the specific meanings of these terms in the embodiments of this disclosure based on the specific circumstances.

[0031] Unless otherwise stated, the term "plurality" means two or more.

[0032] In the embodiment of the present disclosure, the character " / " indicates that the preceding and following objects are in an "or" relationship. For example, A / B means: A or B.

[0033] The term "and / or" describes an association between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or A and B.

[0034] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present disclosure can be combined with each other.

[0035] Combine Figure 1-6 As shown, an embodiment of the present disclosure provides a battery cell, including stacked positive electrode sheets 106 and negative electrode sheets, and a solid electrolyte layer 105 is arranged between adjacent positive electrode sheets 106 and negative electrode sheets, at least one side of the negative electrode sheet circumferentially extends beyond the positive electrode sheet to form an overhang area, and a packaging structure 102 is arranged in the overhang gap area corresponding to the overhang area; wherein, the packaging structure 102 includes a lithium supplement agent, the lithium supplement agent has ion conductivity, and the delithiation product of the lithium supplement agent includes a solid product and lithium ions, and the solid product is electronically insulating.

[0036] In the embodiment of the present disclosure, at least one side of the negative electrode sheet extends beyond the positive electrode sheet to form an overhang area. The overhang area can be formed by extending one side of the negative electrode sheet beyond the positive electrode sheet 106, or by extending multiple sides of the negative electrode sheet beyond the positive electrode sheet to form an overhang area. The packaging structure 102 is arranged in the overhang gap area corresponding to the overhang area. The packaging structure 102 can maintain uniform force on the positive electrode sheet and the negative electrode sheet during battery assembly, application of external pressure and operation, and prevent the positive electrode sheet and the negative electrode sheet from being misaligned. Even in the case of misalignment between the positive electrode sheet and the negative electrode sheet, the packaging structure 102 can prevent direct contact between the positive electrode sheet and the negative electrode sheet, prevent short circuits, and improve the yield and cycle life of the battery.

[0037] In the disclosed embodiments, the lithium supplement has ionic conductivity and can release lithium ions during the battery charging and discharging process, effectively replenishing the reduction in the number of lithium ions caused by SEI film formation and other reasons, thereby increasing the actual available capacity of the battery and improving energy density and cycle performance.

[0038] The battery cell provided by the embodiment of the present disclosure forms an overhang area by extending the negative electrode sheet beyond the positive electrode sheet on at least one side in the circumferential direction, and provides a packaging structure 102 including a lithium supplement in the overhanging gap area corresponding to the overhanging area, thereby effectively combining the insulating support function and the lithium supplement function in the packaging structure 102. The lithium supplement in the packaging structure 102 acts as a lithium source and can effectively release lithium ions during the battery charging process to compensate for the lithium loss caused by factors such as the formation of the SEI film, thereby effectively improving the battery's first coulombic efficiency and the battery's energy density. At the same time, the solid product in the lithium supplement's delithiation product is electronically insulating and will not affect the electrochemical reaction path and stability inside the battery cell. In this way, the overhanging gap area can be fully utilized to achieve the lithium supplement function without reducing the battery's energy density. The packaging structure 102 can also form a stable support for the overhang area, effectively preventing short circuit problems caused by the misalignment of the positive and negative electrode sheets during assembly.

[0039] In some embodiments, the packaging structure 102 is disposed on the circumferential side of the positive electrode sheet 106 corresponding to the overhanging gap area, and the packaging structure 102 and the positive electrode sheet are integrated to form a positive electrode sheet with the packaging structure 102 .

[0040] The encapsulation structure 102 can be directly integrated onto the circumferential side of the positive electrode sheet, forming a positive electrode sheet with the encapsulation structure 102. In this case, the solid electrolyte layer 105 uses a solid electrolyte layer 105 without the encapsulation structure 102, that is, a conventional solid electrolyte layer 105 without lithium supplementation and insulation support functions.

[0041] Optionally, the positive electrode sheet 106 and the negative electrode sheet are both rectangular, and the four circumferential sides of the negative electrode sheet extend beyond the positive electrode sheet to form an overhang area. The corresponding overhanging gap area of ​​the packaging structure 102 is surrounded by the circumferential side of the positive electrode sheet, and the packaging structure 102 is integrated with the positive electrode sheet to form a positive electrode sheet with the packaging structure 102.

[0042] The packaging structure 102 is arranged around the four sides of the positive electrode sheet, forming a U-shaped or U-shaped structure. The packaging structure 102 is arranged around the four sides of the positive electrode sheet 106, making full use of the overhanging gap area corresponding to the overhang area for lithium replenishment. At the same time, the electronic insulation properties of the solid product in the lithium de-lithiation product of the lithium replenisher ensure that the packaging structure 102 does not interfere with the electrochemical reaction path and stability within the battery cell after lithium replenishment. It can provide stable support for the overhang area around the positive electrode sheet, effectively preventing short circuit problems caused by misalignment between the positive and negative electrode sheets during assembly.

[0043] The corresponding overhanging gap area of ​​the packaging structure 102 is surrounded by the circumferential side of the positive electrode sheet, and is integrated with the positive electrode sheet to form a positive electrode sheet with the packaging structure 102. This layout method tightly combines the packaging structure 102 with the circumferential side of the positive electrode sheet and realizes an integrated setting, which can effectively enhance the overall stability of the structure. During the lithium replenishment process, lithium ions exhibit two movement paths. One is to move directly from the packaging structure 102 to the negative electrode sheet through the solid electrolyte layer 105; the other is to first enter the positive electrode sheet 106 from the packaging structure 102, and then move to the negative electrode sheet through the solid electrolyte layer 105. The integrated setting of the packaging structure 102 and the positive electrode sheet can effectively reduce the interface contact resistance between the two and reduce the power loss inside the battery. In addition, the integrated design of the packaging structure 102 and the positive electrode sheet can simplify the manufacturing and assembly process and improve production efficiency.

[0044] In some embodiments, the packaging structure 102 corresponds to the overhanging gap area and is arranged on the end face of the solid electrolyte layer 105 facing the positive electrode plate 106, forming a solid electrolyte layer 105 with a packaging structure 102. The packaging structure 102 is constructed with an interlocking groove 1021, and the interlocking groove 1021 is adapted to the size of the positive electrode plate so that the positive electrode plate can be embedded in the interlocking groove 1021.

[0045] The encapsulation structure 102 is provided on the end surface of the solid electrolyte layer 105 facing the positive electrode sheet, corresponding to the overhanging gap area. After assembly, the positive electrode sheet can be embedded in the embedding groove of the end-capping structure. Similarly, the encapsulation structure 102 can be provided in the overhanging gap area corresponding to the overhang area. In this case, the positive electrode sheet adopts a positive electrode sheet without the encapsulation structure 102, that is, a conventional positive electrode sheet without lithium supplementation and insulation support functions.

[0046] Optionally, both the positive electrode sheet and the negative electrode sheet are rectangular, the solid electrolyte layer 105 is a rectangle with the same size as the negative electrode sheet, and the corresponding overhanging gap area of ​​the packaging structure 102 is arranged on the end face of the solid electrolyte layer 105 facing the positive electrode sheet, forming a solid electrolyte layer 105 with a packaging structure 102.

[0047] The corresponding overhanging gap area of ​​the packaging structure 102 is arranged on the end face of the solid electrolyte layer 105 facing the positive electrode sheet, forming a U-shaped or U-shaped structure. After the positive electrode sheet is assembled with the solid electrolyte layer 105, the positive electrode sheet can be embedded in the interlocking groove 1021 of the packaging structure 102, and the packaging structure 102 can make full use of the overhanging gap area corresponding to the overhang area for lithium replenishment. At the same time, the electronic insulation properties of the solid product in the delithiation product of the lithium replenisher ensure that the packaging structure 102 will not interfere with the electrochemical reaction path and stability inside the battery cell after lithium replenishment, and can provide stable support for the overhang area around the positive electrode sheet, effectively preventing short circuit problems caused by misalignment between the positive electrode sheet and the negative electrode sheet during assembly.

[0048] The corresponding overhanging gap area of ​​the packaging structure 102 is arranged on the end face of the solid electrolyte layer 105 facing the positive electrode sheet, forming a solid electrolyte layer 105 with a packaging structure 102, and constructing an interlocking groove 1021 so that the positive electrode sheet can be embedded. This layout method uses the solid electrolyte layer 105 as a carrier to organically combine the packaging structure 102 with the solid electrolyte layer 105. On the one hand, the solid electrolyte layer 105 itself has good ion conductivity, which can provide a more efficient channel for the lithium ion transmission of the lithium supplement, further improving the lithium supplement effect; on the other hand, the design of the interlocking groove 1021 makes the positional relationship between the positive electrode sheet and the solid electrolyte layer 105 more precise, which can improve the overall assembly accuracy and reliability of the battery cell. At the same time, this design also helps to optimize the internal space utilization of the battery cell, making the battery cell structure more compact and further improving the energy density.

[0049] In some embodiments, the positive electrode sheet 106 includes a positive current collector layer 104 and a positive active material layer 103 , wherein the positive active material layer 103 is arranged on the positive current collector layer 104 ; wherein the encapsulation structure 102 is disposed around the circumferential side of the positive active material layer 103 .

[0050] In this embodiment, the positive electrode current collector layer 104 is typically made of a metal material. Optionally, the material of the positive electrode current collector layer 104 includes aluminum foil. The encapsulation structure 102 is disposed around the circumferential side of the positive electrode active material layer 103, fully encapsulating and protecting the positive electrode active material layer 103. This allows the encapsulation structure 102 to be tightly bonded to the positive electrode active material layer 103 while also preventing interference with the contact between the positive electrode active material layer 103 and the solid electrolyte layer 105.

[0051] The positive electrode active material layer 103 includes a positive electrode active material, a solid electrolyte, a first conductive agent and a first binder. In some embodiments, the weight ratio of the positive electrode active material, the solid electrolyte, the first conductive agent and the first binder is 50-89:10-30:0-10:1-3. Optionally, the weight ratio of the positive electrode active material, the solid electrolyte, the first conductive agent and the first binder is 75:20:3:2. Optionally, the positive electrode active material adopts NCM (811) ternary positive electrode, that is, nickel cobalt lithium manganese oxide (811 type) ternary positive electrode material, the solid electrolyte adopts sulfide solid electrolyte (Lithium Phosphorus Sulfur Chloride, LPSC), the chemical formula is Li6PS5Cl, and the first conductive agent adopts vapor-grown carbon fiber (VGCF), and the mass ratio of NCM (811): LPSC: VGCF = 75:20:3:2.

[0052] The first conductive agent can effectively improve the conductivity of the positive electrode active material layer 103. The solid electrolyte provides the positive electrode active material layer 103 with good ionic conductivity. During the battery's charge and discharge process, lithium ions can be rapidly transferred between the positive electrode active material layer 103 and the solid electrolyte layer 105 through the solid electrolyte, thereby reducing polarization during ion transfer and improving the battery's charge and discharge efficiency.

[0053] In some embodiments, the positive electrode active material includes one or more of lithium nickel cobalt aluminum oxide, lithium nickel oxide, lithium sulfide, lithium nickel manganese oxide, lithium manganese oxide, lithium manganese oxide, lithium-rich manganese-based, lithium iron manganese phosphate, lithium cobalt oxide, lithium nickel cobalt manganese oxide, and lithium iron phosphate. These positive electrode active materials have different electrochemical properties and energy density characteristics. For example, lithium nickel cobalt aluminum oxide has high energy density and good cycling stability; lithium iron phosphate has good thermal stability and safety. By selecting the appropriate positive electrode active material or combination thereof, a positive electrode sheet that meets specific needs can be prepared according to different application scenarios and performance requirements.

[0054] In some embodiments, the first binder includes one or more of polyvinylidene fluoride (PVDF)-hexafluoropropylene (HFP)-diisobutyl ketone, fluorinated rubber-isobutyl isobutyrate, fluorinated rubber-butyl butyrate, styrene-ethylene / butylene-styrene block copolymer (SEBS), SEBS-anisole, and polyisobutylene (PIB)-n-heptane. Using any one of these first binders, or a combination of multiple first binder systems, can effectively enhance the bonding between the positive electrode active material, the first conductive agent, and the solid electrolyte.

[0055] Optionally, the positive electrode plate further includes a tab 101 , which is connected to the positive electrode current collector layer 104 .

[0056] Optionally, the positive electrode current collector layer 104 is rectangular, the positive electrode active material layer 103 is rectangular, and the packaging structure 102 is in the shape of a Chinese umbilical cord or a type of a Chinese umbilical cord.

[0057] In some embodiments, the thickness of the packaging structure 102 is 0.5 to 20 mm. Alternatively, the thickness of the packaging structure 102 is 1 to 20 mm. Alternatively, the thickness of the packaging structure 102 is 5 to 20 mm. Alternatively, the thickness of the packaging structure 102 is 10 to 20 mm. Alternatively, the thickness of the packaging structure 102 is 3 mm. It is understood that the thickness of the packaging structure 102 can be any value between 0.5 and 20 mm. Alternatively, the thickness of the packaging structure 102 is the same as the thickness of the positive electrode active material layer 103. Alternatively, the thickness of the packaging structure 102 is the same as the thickness of the positive electrode tab. By controlling the thickness of the packaging structure 102, the lithium supplement agent can be effectively utilized while minimizing the space occupied by the packaging structure 102 within the battery cell. A thinner packaging structure 102 can increase the energy density of the battery cell, while a packaging structure 102 of appropriate thickness can improve the ionic conductivity and structural stability of the lithium supplement agent, thereby achieving an optimal balance between energy density and lithium supplementation effectiveness.

[0058] In some embodiments, the lithium replenisher includes one or more of Li2MoO3, Li2S, Li2S2, Li2S4, Li2S6, Li5FeO4, and Li2C4O4. These lithium replenishers are ionically conductive, and their desorption products include lithium ions and an electronically insulating solid product. This enables the package structure 102 to simultaneously perform both lithium replenishment and insulating support functions. While replenishing lithium, the conductivity of the desorption products does not interfere with the electrochemical reaction pathways and stability within the battery.

[0059] In some embodiments, the solid electrolyte layer 105 includes one or more of an LPSC-type solid electrolyte, a LISICON-type solid electrolyte, a NASICON-type lithium-ion solid electrolyte, a garnet-type solid electrolyte, a perovskite-type solid electrolyte, a Garnet-type solid electrolyte, a LIPON-type solid electrolyte, a Thio-LISICON-type solid electrolyte, an Argyrodite-type solid electrolyte, a Halide-type solid electrolyte, a Hydride-type lithium-ion solid electrolyte, an LGPS-type solid electrolyte, a PEO-type solid electrolyte, a PVDF-type solid electrolyte, a PAN-type solid electrolyte, a PMMA-type solid electrolyte, and a PVC-type solid electrolyte. Optionally, the solid electrolyte layer 105 also includes a fourth binder. Optionally, the mass ratio of the solid electrolyte to the fourth binder in the solid electrolyte layer 105 is 96:4. Optionally, the fourth binder includes SEBS. These solid electrolytes have different ionic conductivity, chemical stability, and mechanical properties. By selecting the appropriate solid electrolyte or combination thereof, the ion transport performance and interfacial stability of the battery cell can be optimized, thereby improving the charge and discharge efficiency and cycle life of the battery. At the same time, different solid-state electrolytes have different thermal stability and safety characteristics, which can meet the battery performance requirements of different application scenarios.

[0060] In some embodiments, the negative electrode plate includes a negative electrode active material layer, which includes a negative electrode active material. The negative electrode active material includes one or more of graphite, silicon, lithium titanate, hard carbon, soft carbon, silicon-carbon, silicon-oxygen, tin-based, lithium-based, and lithium-metal materials. By using a combination of multiple negative electrode active materials, the specific capacity, cycle stability, rapid charge and discharge capability, safety, and low-temperature performance of the negative electrode plate can be improved.

[0061] Optionally, the negative electrode active material layer further includes a third binder, which includes one or more of PVDF-NMP, CMC-deionized water, SEBS, SEBS-anisole, and PIB-n-heptane systems, wherein PVDF-NMP is polyvinylidene fluoride-N-methylpyrrolidone.

[0062] Optionally, the negative electrode active material layer further includes a second conductive agent, and the mass ratio of the negative electrode active material, the second conductive agent, and the third binder is 90:8:2. Optionally, the second conductive agent includes a highly conductive carbon black material (Super P Conductive Carbon Black, SP).

[0063] Optionally, the negative electrode sheet includes a negative electrode active material layer and a negative electrode current collector layer, and the negative electrode active material layer is arranged on the negative electrode current collector layer.

[0064] In this embodiment, the negative electrode current collector layer is generally made of a metal material. Optionally, the negative electrode current collector layer includes copper foil.

[0065] The present disclosure provides a method for preparing the aforementioned battery cell, comprising:

[0066] S110, preparing a positive electrode sheet, a negative electrode sheet and a solid electrolyte layer; wherein the size of the negative electrode sheet is larger than that of the positive electrode sheet on at least one circumferential side, so that the negative electrode sheet has an overhang area.

[0067] S120 , disposing a packaging material on the circumferential side of the positive electrode plate to obtain a positive electrode plate having a packaging structure; wherein the packaging material includes the aforementioned lithium supplement, and the packaging structure corresponds to the overhang area.

[0068] S130 , stacking the negative electrode sheet, the solid electrolyte layer, and the positive electrode sheet in this order to obtain a battery cell.

[0069] The present disclosure provides a method for preparing the aforementioned battery cell, comprising:

[0070] S210, preparing a positive electrode sheet, a negative electrode sheet and a solid electrolyte layer; wherein the size of the negative electrode sheet is larger than that of the positive electrode sheet on at least one circumferential side, so that the negative electrode sheet has an overhang area.

[0071] S220 , disposing a packaging material on the end surface of the solid electrolyte layer facing the positive electrode sheet to obtain a solid electrolyte layer having a packaging structure; wherein the packaging material includes the aforementioned lithium replenisher, and the packaging structure corresponds to the overhang area.

[0072] S230 , stacking the negative electrode sheet, the solid electrolyte layer, and the positive electrode sheet in the order of the negative electrode sheet, the solid electrolyte layer, and the positive electrode sheet to obtain a battery cell.

[0073] The negative electrode sheet, the solid electrolyte layer and the positive electrode sheet are stacked in the order of negative electrode sheet, solid electrolyte layer and positive electrode sheet, which means that the basic stacking unit of the battery cell is composed of the negative electrode sheet, the solid electrolyte layer and the positive electrode sheet stacked in sequence, and when the battery cell contains two or more groups of positive and negative electrode sheets, the two adjacent groups of basic stacking units need to be isolated and ion-conducted by the solid electrolyte layer, forming an overall stacking structure that periodically repeats the order of negative electrode sheet, solid electrolyte layer, positive electrode sheet and solid electrolyte layer.

[0074] In the cell manufacturing method of the disclosed embodiments, packaging material is applied to the circumferential side surfaces of the positive electrode sheet or the end surface of the solid electrolyte layer facing the positive electrode sheet, corresponding to the overhang area. Through a molding process, a composite packaging structure with both lithium replenishment and short-circuit protection is constructed. This method integrates the release of the lithium replenisher and the insulation protection functions into the packaging structure, avoiding the stacking of multiple functional structures such as lithium replenishment layers and insulation layers in traditional solutions. This simplifies the process and improves production efficiency.

[0075] In some embodiments, in step S220, before providing the packaging material on the end surface of the solid electrolyte layer facing the positive electrode plate, the step further includes: transferring the solid electrolyte layer to the negative electrode plate to obtain a negative electrode-solid electrolyte layer composite plate.

[0076] After the solid electrolyte layer is transferred to the negative electrode sheet, a negative electrode-solid electrolyte layer composite sheet is formed. The rigidity of the negative electrode sheet can provide mechanical support for the solid electrolyte layer, thereby improving the structural strength of the solid electrolyte layer. This can improve the pressure bearing capacity of the solid electrolyte layer during the setting process of the packaging material. In addition, the transfer process can achieve a close combination of the solid electrolyte layer and the negative electrode sheet, and can also improve the interface contact quality and stability between the two. At the same time, through the transfer process, the solid electrolyte layer can be evenly covered on the surface of the negative electrode sheet, reducing interface defects and pores, thereby reducing the interface impedance and improving the transmission efficiency of lithium ions at the interface.

[0077] In some embodiments, in step S120 , providing packaging material on the circumferential side of the positive electrode sheet includes: providing packaging material on the empty foil area of ​​the positive electrode sheet using a 3D printing method.

[0078] In some embodiments, in step S220, providing packaging material on the end surface of the solid electrolyte layer facing the positive electrode piece includes: using a 3D printing method to provide packaging material on the end surface of the solid electrolyte layer facing the positive electrode piece.

[0079] Using 3D printing to apply packaging material to the hollow foil area of ​​the positive electrode sheet, or applying packaging material to the end surface of the solid electrolyte layer facing the positive electrode sheet, can achieve precise deposition and shaping of the packaging material. 3D printing can effectively control the dimensional accuracy of the printed packaging structure, effectively reduce the amount of binder and lithium supplement, reduce the waste of raw materials, and lower production costs. At the same time, 3D printing technology has a high degree of automation and production efficiency, which can reduce manual operation errors and improve production efficiency and product quality. It is understood that the application of packaging materials can also be achieved through processes such as coating.

[0080] In some embodiments, the 3D printing method includes: configuring a 3D printing overhang slurry; wherein the 3D printing overhang slurry includes a lithium supplement, a second binder, and a solvent; printing the 3D printing overhang slurry onto the empty foil area of ​​the positive electrode sheet, or printing the 3D printing overhang slurry onto the end face of the solid electrolyte layer facing the positive electrode sheet; and curing to obtain a positive electrode sheet with a packaging structure or a solid electrolyte layer with a packaging structure.

[0081] Optionally, configuring the 3D printing overhang slurry includes: preparing various component raw materials of the 3D printing overhang slurry, mixing them, and obtaining a mixture slurry. Optionally, curing includes: heat treatment in a tube furnace or drying oven under a certain atmosphere for 0.5 to 6 hours, and natural cooling. Optionally, nitrogen, vacuum, oxygen, air, or argon is used for drying in the tube furnace. Optionally, the temperature of the tube furnace or drying oven is between 70 and 500 degrees Celsius.

[0082] In some embodiments, in step S110, a positive electrode sheet is prepared, including: disposing a positive electrode active material layer on a positive electrode current collector layer, the positive electrode current collector layer being larger than the positive electrode active material layer on at least one circumferential side, so that the positive electrode sheet forms a hollow foil area; wherein the hollow foil area corresponds to the overhang area of ​​the negative electrode sheet.

[0083] The empty foil area on the positive electrode current collector layer provides suitable space for the packaging structure. At the same time, the positive electrode current collector layer, as a carrier of the packaging structure, can also improve the structural strength of the positive electrode sheet.

[0084] Optionally, the encapsulation structure is disposed around the circumferential side of the positive electrode sheet, corresponding to the overhanging gap region. When the encapsulation structure is integrated with the positive electrode sheet, the outer edge of the encapsulation structure is flush with the positive electrode current collector layer. In the positive electrode sheet, the encapsulation structure is disposed around the circumferential side of the positive electrode active material layer. The thickness of the encapsulation structure is the same as that of the positive electrode active material layer, so that the positive electrode active material layer is effectively protected and encapsulated by the encapsulation structure. Optionally, the dimensions of the positive electrode active material layer are 8.4×11.4 cm, and the dimensions of the positive electrode current collector layer are 9×12 cm. A 3 mm edge is exposed on each of the four sides of the positive electrode current collector layer.

[0085] In some embodiments, in step S130, before stacking the negative electrode sheet, the solid electrolyte layer and the positive electrode sheet, the preparation method further includes: transferring the solid electrolyte layer to the negative electrode sheet to obtain a negative electrode-solid electrolyte layer composite sheet.

[0086] The transfer process allows for a close bond between the solid electrolyte layer and the negative electrode, improving the interface contact quality and stability between the two. Furthermore, the transfer process allows the solid electrolyte layer to evenly coat the surface of the negative electrode, reducing interface defects and pores, thereby lowering interfacial impedance and improving lithium ion transmission efficiency at the interface.

[0087] In some embodiments, after stacking the negative electrode sheet, the solid electrolyte layer, and the positive electrode sheet to obtain a laminate structure, the laminate structure can be compressed to obtain a battery cell. The compression process can be performed by isostatic pressing, which can press and connect the layers in the laminate structure.

[0088] An embodiment of the present disclosure provides a 3D printing overhang slurry, which is used as a packaging material for the packaging structure 102 of the aforementioned battery cell, or as a packaging material in the aforementioned battery cell preparation method. The 3D printing overhang slurry includes, by mass percentage, 10% to 50% of a lithium replenisher, 1% to 30% of a second binder, and 2% to 89% of a solvent. The lithium replenisher has ionic conductivity, and a delithiation product of the lithium replenisher includes a solid product and lithium ions, and the solid product is electronically insulating.

[0089] Optionally, the 3D printing overhang slurry also includes a dispersant in an amount of 0.1% to 4%. The mass percentage of the dispersant is 0.1% to 4%, calculated based on the total mass of the lithium supplement, the second binder, and the solvent (excluding the dispersant) as 100%. The lithium supplement, the second binder, and the solvent form the base slurry, and the dispersant is a component added to the base slurry. Optionally, the dispersant includes polyetherimide, and the mass percentage of polyetherimide is 2% (calculated based on the total mass of the lithium supplement, the second binder, and the solvent as 100%). The dispersant can improve the properties of the 3D printing overhang slurry. Specifically, it can reduce the surface tension of the particles, prevent agglomeration of solid particles such as the lithium supplement and the second binder, improve the uniformity of the 3D printing overhang slurry, and prevent the 3D printing overhang slurry from clogging the nozzle during printing. The dispersant can also maintain the fluidity of the 3D printing overhang slurry.

[0090] Optionally, the viscosity of the 3D printing overhang slurry is 2000~10000 mPa·s. Optionally, the viscosity of the 3D printing overhang slurry is 4000~10000 mPa·s. Optionally, the viscosity of the 3D printing overhang slurry is 6000~10000 mPa·s. Optionally, the viscosity of the 3D printing overhang slurry is 8000~10000 mPa·s. This allows the 3D printing overhang slurry to achieve a balance between fluidity and support. The 3D printing overhang slurry has a certain fluidity and can smoothly pass through the narrow aperture of the 3D printing nozzle to avoid clogging due to excessive viscosity, and is suitable for continuous extrusion printing. At the same time, the above viscosity range can also prevent the slurry from excessively flowing, avoiding dripping or deformation due to gravity after extrusion, and is suitable for the molding of the packaging structure 102 in the overhanging gap area.

[0091] In this embodiment, the viscosity of the 3D printing overhang slurry is tested at room temperature using a rotational viscometer.

[0092] Optionally, the fineness of the 3D printing overhang slurry is 5-30 μm. Optionally, the fineness of the 3D printing overhang slurry is 10-30 μm. Optionally, the fineness of the 3D printing overhang slurry is 15-30 μm. Optionally, the fineness of the 3D printing overhang slurry is 20-30 μm. This can improve the fluidity and dispersion uniformity of the 3D printing overhang slurry, evenly disperse solid components such as the lithium supplement and the second binder, and reduce sedimentation and stratification.

[0093] In this embodiment, the fineness of the 3D printing overhang slurry is measured using a scraper fineness meter and tested at room temperature.

[0094] Optionally, the particle size of the lithium supplement agent is 20 nm~10 μm. Optionally, the particle size of the lithium supplement agent is 100 nm~10 μm. Optionally, the particle size of the lithium supplement agent is 500 nm~10 μm. Optionally, the particle size of the lithium supplement agent is 1~10 μm. This particle size range is wide, covering nanometer to micrometer scales. Smaller particles (such as 20 nm) can provide a larger specific surface area, accelerate the release of lithium ions, and improve lithium supplement efficiency. Larger particles (such as 10 μm) help maintain the structural stability of the lithium supplement agent, prevent it from quickly dissolving or aggregating in the electrolyte, thereby continuously releasing lithium ions for a longer period of time and improving battery cycle stability.

[0095] Optionally, the mass ratio of the lithium replenisher to the second binder is 100-0.01. A higher content of the lithium replenisher can enhance the lithium replenishment capacity of the 3D printed overhang slurry, effectively replenishing lithium loss in solid-state batteries. An appropriate amount of the second binder can improve the adhesion and formability of the 3D printed overhang slurry, enabling it to form a stable structure during the 3D printing process.

[0096] Optionally, the lithium supplement agent is Li2S, the second binder is PIB, the solvent is n-heptane, and the mass ratio of Li2S, PIB and n-heptane is 16:4:80.

[0097] The use of the 3D printing overhang slurry in this embodiment can achieve efficient preparation and precise molding of the packaging structure 102. The 3D printing overhang slurry serves as a packaging material, and its components include a lithium replenisher, a second binder, and a solvent. The lithium replenisher has ionic conductivity and can release lithium ions during the battery charging and discharging process to replenish lithium loss; the second binder can effectively bond the lithium replenisher and other components together to improve the formability and stability of the slurry; the solvent can adjust the rheological properties of the slurry to make it suitable for the 3D printing process. By reasonably controlling the proportion of each component, the performance of the 3D printing overhang slurry can be optimized, so that it has good printability, molding accuracy and mechanical properties during the 3D printing process.

[0098] In some embodiments, the second binder includes one or more of polyethylene terephthalate, polyvinyl chloride, hydroxyethyl cellulose, polyisobutylene (PIB), polyphenylene ether (PPO), polyimide (PI), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polyethylene glycol (PEG), polyethylene oxide (PEO), hydroxypropyl cellulose, styrene-butadiene rubber (SBR), polyacrylic acid (PAA), polyvinyl pyrrolidone, and polyacrylate.

[0099] By using one or a combination of these second binders, the slurry's bonding strength and flexibility can be improved, enabling it to form a stable structure during 3D printing and maintain structural integrity during battery operation. Furthermore, a good binder can improve the slurry's processing properties, increasing production efficiency and product quality, further enhancing the battery's overall performance.

[0100] In some embodiments, the solvent includes one or more of N-methylpyrrolidone, anisole, polyvinylpyrrolidone, ethanol, toluene, acetonitrile, glycerol, and n-heptane.

[0101] A good solvent can improve the stability of the slurry, preventing component precipitation and separation, thereby improving the quality and performance of the slurry. Furthermore, the above solvent can evaporate quickly during the slurry drying process, forming a dense package structure 102 and further improving the performance of package structure 102. By using one or a combination of these solvents, the viscosity, surface tension, and fluidity of the slurry can be optimized, making it suitable for 3D printing processes.

[0102] The embodiments of the present disclosure further provide a solid-state battery, comprising: a battery cell according to any of the aforementioned embodiments; or a battery cell obtained by using the method for preparing the battery cell according to any of the aforementioned embodiments.

[0103] The battery cell of the aforementioned embodiment is welded to the tab 101, vacuum packaged, and subjected to isostatic pressing to obtain a solid-state battery.

[0104] Optionally, the isostatic pressing treatment is performed at 500 MPa for 8 minutes. The isostatic pressing process presses and connects the stacked negative electrode sheet, solid electrolyte layer 105, and positive electrode sheet layers. The high pressure ensures a tight fit between the multilayer structure and eliminates interlayer gaps. Optionally, the solid-state battery is a pouch cell.

[0105] The following specific examples are given to specifically illustrate the battery cells and their preparation methods, 3D printing overhang slurries, 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 part of the embodiments of the present application, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present application and its applications.

[0106] If no specific techniques or conditions are specified in the examples, the experiments were carried out according to the techniques or conditions described in the literature in the field or according to the product instructions. All reagents or instruments used without specifying the manufacturer are commercially available conventional products.

[0107] Example 1

[0108] A battery cell comprises stacked positive and negative electrode sheets, with a solid electrolyte layer disposed between adjacent positive and negative electrode sheets, at least one circumferential side of the negative electrode sheet extending beyond the positive electrode sheet to form an overhang region, and a packaging structure disposed in a corresponding overhanging gap region of the overhang region; wherein the packaging structure comprises a lithium replenisher, the lithium replenisher having ionic conductivity, and a delithiation product of the lithium replenisher comprising a solid product and lithium ions, and the solid product being electronically insulated; the packaging structure is disposed around the circumferential side of the positive electrode sheet corresponding to the overhanging gap region, and the packaging structure is integrated with the positive electrode sheet to form a positive electrode sheet having a packaging structure.

[0109] See also Figure 1-3 As shown, the battery cell of this embodiment 1 includes a positive electrode sheet with a packaging structure, the packaging structure is arranged around the circumferential side of the positive electrode active material layer, and the solid electrolyte layer is not provided with a packaging structure.

[0110] In this embodiment 1, for the subsequent solid-state battery assembly and battery performance testing, the following positive electrode sheet, negative electrode sheet and solid electrolyte layer with a packaging structure are specifically adopted.

[0111] A positive electrode sheet with an encapsulated structure: The composition of the positive electrode active material layer is NCM(811):LPSC:VGCF:SEBS=75:20:3:2 by mass, and the positive electrode current collector layer is aluminum foil. The size of the positive electrode active material layer is 8.4×11.4 cm, the size of the positive electrode current collector layer is 9×12 cm, and there is a 3 mm exposed aluminum foil edge (i.e., empty foil area) on each of the four sides of the positive electrode current collector layer. Among them, NCM(811) material refers to lithium nickel cobalt manganese oxide (811 type) ternary positive electrode material, LPSC is a sulfide-silver-germanite type sulfide solid electrolyte, VGCF (vapor-grown carbon fiber) is the first conductive agent, and SEBS (styrene-ethylene / butylene-styrene block copolymer) is the first binder. The packaging material of the packaging structure is 3D printing overhang slurry. The components of the 3D printing overhang slurry include Li2S:PIB:n-heptane in a mass ratio of 16:4:80, among which Li2S is a lithium supplement, PIB (polyisobutylene) is a second binder, and n-heptane is a solvent. The 3D printing overhang slurry also includes a polyetherimide dispersant with a mass percentage of 2% (calculated based on the total mass of Li2S, PIB and n-heptane as 100%).

[0112] Negative electrode sheet: The negative electrode active material layer is composed of a mass ratio of graphite: secondary conductive agent: tertiary binder = 90:8:2. The negative electrode current collector layer uses copper foil. The secondary conductive agent is a highly conductive carbon black material SP. The tertiary binder can be any of PVDF-NMP, CMC-deionized water, SEBS, SEBS-anisole, or PIB-n-heptane.

[0113] Solid electrolyte layer: The mass ratio of sulfide electrolyte LPSC to the fourth binder SEBS is 96:4.

[0114] The method for preparing the battery cell of this embodiment 1 comprises the following steps:

[0115] Preparation of positive electrode sheet: dissolving the first binder SEBS in anisole solvent to obtain binder glue A; mixing NCM (811) ternary positive electrode, LPSC, VGCF with binder glue A to obtain positive electrode slurry; wherein, the mass ratio of each component in the positive electrode slurry is NCM (811): LPSC: VGCF: SEBS = 75:20:3:2; coating the positive electrode slurry on the positive electrode current collector layer aluminum foil by intermittent coating method, and vacuum drying at 80 ° C to obtain a positive electrode sheet, wherein the dried positive electrode slurry is the positive electrode active material layer; die-cutting the positive electrode sheet to obtain a positive electrode active material area with a size of 8.4×11.4 cm, an aluminum foil positive electrode current collector layer with a size of 9×12 cm, and a 3 mm exposed aluminum foil edge on each of the four sides of the aluminum foil, and the exposed aluminum foil edge is the empty foil area.

[0116] A positive electrode sheet with an encapsulated structure was prepared by a 3D printing method: a PIB glue solution with a mass concentration of 1:20 was prepared using n-heptane and PIB, and a lithium supplement Li2S was added to the PIB glue solution to prepare a slurry of Li2S:PIB:n-heptane = 16:4:80. Then, 2% of a polyetherimide dispersant was additionally added and homogenized to prepare a 3D printed overhang slurry; the 3D printed overhang slurry was placed in the loading area of ​​a 3D printer, and the printer parameters were set to print the 3D printed overhang slurry on the empty foil area of ​​the positive electrode current collector layer; the printing parameters were an injection speed of 6 mL / min and a needle printing speed of 50 mm / s; the printing width was designed to be 3 mm, and the thickness of the 3D printed overhang slurry was consistent with the thickness of the positive electrode sheet; the printed positive electrode sheet was placed in a tube furnace for drying and heating. The heat treatment atmosphere was argon, the temperature was 100 °C, and the time was 3 h to obtain a positive electrode sheet with an encapsulated structure.

[0117] Preparation of negative electrode sheet: dissolving the third binder PIB in the organic solvent dodecane to obtain binder glue B; mixing the graphite negative electrode, the second conductive agent SP and the binder glue B to obtain a negative electrode slurry; wherein the components of the negative electrode slurry are graphite: second conductive agent: third binder = 90:8:2 by mass ratio; coating the negative electrode slurry on the copper foil of the negative electrode current collector layer, and vacuum drying at 80°C to obtain a negative electrode sheet, wherein the dried negative electrode slurry is the negative electrode active material layer.

[0118] Preparation of the solid electrolyte layer: Dissolve the fourth binder SEBS in the organic solvent dodecane to obtain binder glue C; dissolve the sulfide electrolyte LPSC in the binder glue C and stir for 2 hours to obtain an electrolyte slurry; wherein, the ratio of the sulfide electrolyte to the fourth binder in the electrolyte slurry is 96:4; the electrolyte slurry is coated on a stainless steel foil and dried at 100°C in a nitrogen atmosphere for 2 hours to obtain an electrolyte sheet, wherein the dried electrolyte slurry is the solid electrolyte layer.

[0119] Preparation of negative electrode-solid electrolyte layer composite electrode sheet: The solid electrolyte layer of the electrolyte sheet is transferred from the stainless steel foil to the negative electrode electrode sheet to obtain a negative electrode-solid electrolyte layer composite electrode sheet; the negative electrode-solid electrolyte layer composite electrode sheet is die-cut to have the same length and width dimensions as the positive electrode electrode sheet with an encapsulated structure, which is 9×12 cm.

[0120] Lamination operation: The positive electrode sheet with a packaging structure is laminated to the solid electrolyte layer side of the negative electrode-solid electrolyte layer composite sheet to form a structure consisting of a copper foil negative electrode current collector layer, a negative electrode active material layer, a solid electrolyte layer, a positive electrode active material layer (surrounded by a packaging structure) and an aluminum foil positive electrode current collector layer from bottom to top to obtain a battery cell.

[0121] In Example 1, the cells were assembled into a solid-state battery, including tab welding, vacuum packaging, and isostatic pressing. The isostatic pressing parameters in the assembly process were 500 MPa for 8 minutes, and the remaining assembly processes were conventional.

[0122] Example 2

[0123] A battery cell includes stacked positive and negative electrode sheets, with a solid electrolyte layer arranged between adjacent positive and negative electrode sheets, at least one side of the negative electrode sheet protruding from the positive electrode sheet in a circumferential direction to form an overhang region, and a packaging structure is provided in a hanging gap region corresponding to the overhang region; wherein the packaging structure includes a lithium replenisher, the lithium replenisher has ion conductivity, and a delithiation product of the lithium replenisher includes a solid product and lithium ions, and the solid product is electronically insulated; the packaging structure is provided at the end face of the solid electrolyte layer facing the positive electrode sheet corresponding to the hanging gap region, forming a solid electrolyte layer with a packaging structure, and the packaging structure is constructed with an embedding groove, which is adapted to the size of the positive electrode sheet so that the positive electrode sheet can be embedded in the embedding groove.

[0124] See also Figure 4-6 As shown, the battery cell of this embodiment 2 includes a solid electrolyte layer with a packaging structure. The packaging structure corresponds to the overhanging gap area provided on the end surface of the solid electrolyte layer facing the positive electrode sheet, and the positive electrode sheet is not provided with a packaging structure.

[0125] In this embodiment 2, for the subsequent solid-state battery assembly and battery performance testing, the following positive electrode plate and negative electrode-solid electrolyte layer composite plate with packaging structure are specifically used.

[0126] Positive electrode sheet: The composition of the positive electrode active material layer is NCM(811):LPSC:VGCF:SEBS = 75:20:3:2 by mass, and the positive electrode current collector layer is aluminum foil. The dimensions of the positive electrode sheet are 8.4 × 11.4 cm, that is, the dimensions of the positive electrode active material layer and the positive electrode current collector layer are both 8.4 × 11.4 cm.

[0127] This encapsulated negative electrode-solid electrolyte composite electrode sheet features a negative electrode active material layer composed of a mass ratio of graphite: secondary conductive agent: tertiary binder of 90:8:2. The negative electrode current collector layer utilizes copper foil. The secondary conductive agent is a highly conductive carbon black material (SP), and the tertiary binder can be selected from PVDF-NMP, CMC-deionized water, SEBS, SEBS-anisole, or PIB-n-heptane. The solid electrolyte layer is composed of a sulfide electrolyte (LPSC) and a fourth binder (SEBS) of 96:4. The packaging material of the packaging structure is 3D printing overhang slurry. The components of the 3D printing overhang slurry include Li2S:PIB:n-heptane in a mass ratio of 16:4:80, among which Li2S is a lithium supplement, PIB (polyisobutylene) is a second binder, and n-heptane is a solvent. The 3D printing overhang slurry also includes a polyetherimide dispersant with a mass percentage of 2% (calculated based on the total mass of Li2S, PIB and n-heptane as 100%).

[0128] The preparation method of the battery cell of this embodiment 2 includes the following steps:

[0129] Preparation of positive electrode sheet: dissolving the first binder SEBS in anisole solvent to obtain binder glue A; mixing NCM (811) ternary positive electrode, LPSC, VGCF with binder glue A to obtain positive electrode slurry; wherein, the mass ratio of each component in the positive electrode slurry is NCM (811): LPSC: VGCF: SEBS = 75:20:3:2; coating the positive electrode slurry on the aluminum foil of the positive electrode collector layer, and vacuum drying at 80 ° C to obtain a positive electrode sheet, wherein the dried positive electrode slurry is the positive electrode active material layer; die-cutting the positive electrode sheet to obtain a positive electrode sheet with a size of 8.4×11.4 cm in which the positive electrode active material area completely covers the positive electrode collector layer.

[0130] Preparation of negative electrode sheet: dissolving the third binder PIB in the organic solvent dodecane to obtain binder glue B; mixing the graphite negative electrode, the second conductive agent SP and the binder glue B to obtain a negative electrode slurry; wherein, the components of the negative electrode slurry are graphite: second conductive agent: third binder = 90:8:2 by mass ratio; coating the negative electrode slurry on the copper foil of the negative electrode current collector layer, and vacuum drying at 80°C to obtain a negative electrode sheet, wherein the dried negative electrode slurry is the negative electrode active material layer.

[0131] Preparation of the solid electrolyte layer: dissolving the fourth binder SEBS in the organic solvent dodecane to obtain binder glue C; dissolving the sulfide electrolyte LPSC in the binder glue C and stirring for 2 hours to obtain an electrolyte slurry; wherein, the ratio of the sulfide electrolyte to the fourth binder in the electrolyte slurry is 96:4; the electrolyte slurry is coated on a stainless steel foil and dried at 100°C in a nitrogen atmosphere for 2 hours to obtain an electrolyte sheet, wherein the dried electrolyte slurry is the solid electrolyte layer.

[0132] Preparation of negative electrode-solid electrolyte layer composite electrode sheet: transfer the solid electrolyte layer of the electrolyte sheet from the stainless steel foil to the negative electrode electrode sheet to obtain a negative electrode-solid electrolyte layer composite electrode sheet; die-cut the negative electrode-solid electrolyte layer composite electrode sheet to a length and width size of 9×12 cm.

[0133] The negative electrode-solid electrolyte layer composite electrode with an encapsulated structure was prepared by a 3D printing method: n-heptane and PIB were used to prepare a PIB glue with a mass concentration of 1:20, and the lithium supplement Li2S was added to the PIB glue to prepare a slurry of Li2S:PIB:n-heptane = 16:4:80. Then, 2% of polyetherimide dispersant was additionally added and homogenized to prepare a 3D printing overhang slurry; the 3D printing overhang slurry was placed in the loading area of ​​the 3D printer, and the printer parameters were set to print the 3D printing overhang slurry along the circumferential direction on the end face of the solid electrolyte layer facing the positive electrode; among which, the printing parameters were an injection speed of 6 mL / min, a needle printing speed of 50 mm / s; the printing width was designed to be 3 The thickness of the 3D printed overhang slurry was consistent with that of the positive electrode. The printed negative electrode-solid electrolyte layer composite electrode was placed in a tube furnace for drying and heating in an argon atmosphere at 80°C for 3 hours, ultimately obtaining a negative electrode-solid electrolyte layer composite electrode with an encapsulated structure. The solid electrolyte layer formed a solid electrolyte layer with an encapsulated structure.

[0134] Lamination operation: The positive electrode sheet is laminated to the solid electrolyte layer side of the negative electrode-solid electrolyte layer composite sheet with a packaging structure, and the positive electrode sheet is embedded in the interlocking groove of the packaging structure to form a structure from bottom to top consisting of a copper foil negative electrode current collector layer, a negative electrode active material layer, a solid electrolyte layer (with a packaging structure), a positive electrode active material layer and an aluminum foil positive electrode current collector layer to obtain a battery cell.

[0135] In Example 2, the cells were assembled into a solid-state battery, including tab welding, vacuum packaging, and isostatic pressing. The isostatic pressing parameters in the assembly process were 500 MPa for 8 minutes, and the remaining assembly processes were conventional.

[0136] Comparative Example 1

[0137] Unlike Examples 1 and 2, the battery cell of Comparative Example 1 does not have an encapsulation structure. In the preparation method of the battery cell of Comparative Example 1, after preparing the negative electrode-solid electrolyte layer composite electrode sheet, the process of preparing the negative electrode-solid electrolyte layer composite electrode sheet with an encapsulation structure using a 3D printing method is not performed. The remaining steps and parameters are the same as those of Example 2.

[0138] Comparative Example 2

[0139] Unlike Examples 1 and 2, the battery cell of Comparative Example 2 does not have an encapsulation structure, and the positive electrode sheet contains a lithium supplement. In the preparation method of the battery cell of Comparative Example 2, during the step of preparing the positive electrode sheet, the lithium supplement Li2S is directly added to the positive electrode slurry, wherein the components of the positive electrode slurry are NCM (811): LPSC: Li2S: VGCF: SEBS = 72:20:3:3:2 by mass, to obtain a positive electrode sheet containing a lithium supplement. After preparing the negative electrode-solid electrolyte layer composite electrode sheet, the processing step of preparing the negative electrode-solid electrolyte layer composite electrode sheet with an encapsulation structure using a 3D printing method is not performed, resulting in the battery cell having no encapsulation structure. The remaining steps and parameters are the same as those of Example 2.

[0140] Comparative Example 3

[0141] Unlike Examples 1 and 2, the battery cell of Comparative Example 3 is not provided with a packaging structure, and a positive electrode lithium replenishing coating 16 is provided on the surface of the positive electrode plate. In the preparation method of the battery cell of Comparative Example 3, in the step of preparing the positive electrode plate, a step of mixing the lithium replenishing agent, the conductive agent and the binder glue A is added to obtain a lithium replenishing agent mixed slurry, wherein the components of the lithium replenishing agent mixed slurry are lithium replenishing agent Li2S: conductive agent VGCF: binder SEBS=60:38:2 in a mass ratio, and before the positive electrode plate is die-cut, the lithium replenishing agent mixed slurry is applied to the surface of the positive electrode plate to obtain a positive electrode plate containing a positive electrode lithium replenishing coating 16; and after preparing the negative electrode-solid electrolyte layer composite plate, the processing step of preparing the negative electrode-solid electrolyte layer composite plate with a packaging structure by a 3D printing method is not performed, so that the battery cell has no packaging structure. The remaining steps and parameters are the same as those in Example 2. The battery cell structure of this Comparative Example 3 is as follows: Figure 7 shown.

[0142] Comparative Example 4

[0143] Unlike Example 2, the battery cell of Comparative Example 4 does not contain a lithium supplement in its packaging structure. In the preparation method of the battery cell of Comparative Example 4, during the step of preparing the negative electrode-solid electrolyte layer composite electrode sheet with the packaging structure using a 3D printing method, the lithium supplement Li2S was not added to the PIB glue. Instead, alumina was added to the PIB glue to create a slurry of alumina:PIB:n-heptane = 16:4:80, eliminating the lithium supplement in the packaging structure. The remaining steps and parameters were the same as in Example 2.

[0144] Comparative Example 5

[0145] Unlike Example 2, the battery cell of Comparative Example 5 does not contain a lithium supplement agent in its packaging structure, and a lithium supplement coating is provided on the surface of the positive electrode. In the preparation method of the battery cell of Comparative Example 5, during the preparation of the positive electrode, a step is added in which a lithium supplement agent, a conductive agent, and a binder glue solution A are mixed to form a lithium supplement agent mixed slurry. The lithium supplement agent mixed slurry comprises the following components: lithium supplement agent Li2S: conductive agent VGCF: binder SEBS = 60:38:2 by mass. Before die-cutting the positive electrode, the lithium supplement agent mixed slurry is applied to the surface of the positive electrode to form a positive electrode with a lithium supplement coating. Furthermore, during the preparation of the negative electrode-solid electrolyte layer composite electrode sheet with a packaging structure using a 3D printing method, the lithium supplement agent Li2S is not added to the PIB glue solution, resulting in a lithium supplement agent-free packaging structure. The remaining steps and parameters are the same as those of Example 2.

[0146] Comparative Example 6

[0147] Unlike Example 2, the battery cell of Comparative Example 6 does not contain a lithium supplement in its packaging structure, and the positive electrode sheet contains a lithium supplement. In the preparation method of the battery cell of Comparative Example 6, during the step of preparing the positive electrode sheet, the lithium supplement Li2S is directly added to the positive electrode slurry, wherein the components of the positive electrode slurry are NCM (811): LPSC: Li2S: VGCF: SEBS = 72:20:3:3:2 by mass, to obtain a positive electrode sheet containing a lithium supplement. Furthermore, during the step of preparing the negative electrode-solid electrolyte layer composite sheet having a packaging structure using a 3D printing method, the lithium supplement Li2S is not added to the PIB glue solution, so that the packaging structure does not contain a lithium supplement. The remaining steps and parameters are the same as those of Example 2.

[0148] The cells of Examples 1 and 2, and Comparative Examples 1 to 6 were assembled to obtain solid-state batteries, and charge and discharge tests were performed under a pressure of 30 MPa. The obtained charge and discharge test performance data are shown in Table 1.

[0149] From the test results of the embodiments and comparative examples in Table 1, it can be found that the solid-state battery containing the packaging structure can effectively prevent the battery from short-circuiting during pressurized assembly and pressurized operation, and the battery survival rate is relatively high. Moreover, compared with the comparative example in which the lithium replenisher is set in the positive electrode plate or in the lithium replenisher coating on the surface of the positive electrode plate, Examples 1 and 2 set the lithium replenisher in the packaging structure, which can achieve the lithium replenishment effect while avoiding affecting the energy density of the battery. The first average coulombic efficiency, the 50th cycle capacity retention rate, and the positive electrode surface capacity are all relatively high.

[0150] Table 1

[0151]

[0152] A comparison of the test data from Example 1, Example 2, and Comparative Example 1 shows that Examples 1 and 2, which incorporate the packaging structure, have higher battery survival rates, while Comparative Example 1, which lacks the packaging structure, exhibits extremely low cell survival rates and 50-cycle battery survival rates. Furthermore, the packaging structures of Examples 1 and 2 contain a lithium supplement, resulting in higher initial coulombic efficiency and higher capacity retention.

[0153] Comparison of the test data from Example 1, Example 2, and Comparative Example 2 shows that Examples 1 and 2, which incorporate the packaging structure, have higher battery survival rates, while Comparative Example 2, which does not incorporate the packaging structure, has extremely low cell survival rates and 50-cycle battery survival rates. Compared to Comparative Example 2, which directly incorporates the lithium supplement into the positive electrode sheet, Examples 1 and 2, which incorporate the lithium supplement into the packaging structure, achieve higher first-pass average coulombic efficiency and 50-cycle capacity retention, as well as higher positive electrode areal capacity, resulting in higher battery capacity and battery energy density.

[0154] By comparing the test data of Example 1 and Comparative Example 3, it can be seen that compared with Comparative Example 3 in which a lithium replenishing coating is provided on the surface of the positive electrode plate, Example 1 adopts a packaging structure containing a lithium replenishing agent, which enables the battery to have a higher first coulombic efficiency and cycle life. At the same time, due to the support and anti-short-circuit effect of the packaging structure, the battery survival rate of Example 1 is much greater than that of Comparative Example 3.

[0155] By comparing the test data of Example 2 and Comparative Example 4, it can be seen that compared with the packaging structure without lithium replenisher in Comparative Example 4, the packaging structure containing lithium replenisher in Example 2 can make the battery have higher first coulombic efficiency and cycle life.

[0156] By comparing the test data of Example 2 with Comparative Examples 5 and 6, it can be seen that compared with providing the lithium supplement agent in the form of a coating on the positive electrode surface and directly adding the lithium supplement agent into the positive electrode, filling the lithium supplement agent into the packaging structure enables the battery to have a higher positive electrode surface capacity, thereby enabling the battery to have a higher battery capacity and battery energy density.

[0157] The above description and the accompanying drawings sufficiently illustrate the embodiments of the present disclosure to enable those skilled in the art to practice them. Other embodiments may include structural, logical, electrical, process and other changes. The embodiments represent only possible variations. Unless expressly required, individual components and functions are optional, and the order of operations may vary. Portions and features of some embodiments may be included in or replace portions and features of other embodiments. Moreover, the terms used in this application are only used to describe the embodiments and are not used to limit the claims. As used in the description of the embodiments and claims, the singular forms "a", "an" and "the" are intended to also include the plural forms unless the context clearly indicates otherwise. Similarly, the term "and / or" as used in this application means any and all possible combinations of one or more of the associated listings. In addition, when used in this application, the term "comprise" and its variations "comprises" and / or comprising refer to the presence of 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 thereof. In the absence of further restrictions, an element defined by the sentence "comprising a..." does not exclude the presence of other identical elements in the process, method or device that includes the element. In this article, each embodiment may focus on the differences from other embodiments, and the same and similar parts between the various embodiments can be referenced to each other. For the methods, products, etc. disclosed in the embodiments, if they correspond to the method part disclosed in the embodiments, then the relevant parts can be referred to the description of the method part.

[0158] Those skilled in the art will appreciate that the units and steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software may depend on the specific application and design constraints of the technical solution. The technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the embodiments of the present disclosure. The technicians will 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 aforementioned method embodiments and will not be repeated here.

[0159] The flowcharts and block diagrams in the accompanying drawings show the possible implementation architectures, functions and operations of the systems, methods and computer program products according to the embodiments of the present disclosure. In this regard, each box in the flowchart or block diagram can represent a module, program segment or part of the code, and the module, program segment or part of the code contains one or more executable instructions for implementing the specified logical functions. In some alternative implementations, the functions marked in the box can also occur in an order different from that marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, or they can sometimes be executed in the opposite order, which can depend on the functions involved. In the descriptions corresponding to the flowcharts and block diagrams in the accompanying drawings, the operations or steps corresponding to different boxes can also occur in an order different from that disclosed in the description, and sometimes there is no specific order between different operations or steps. For example, two consecutive operations or steps can actually be executed substantially in parallel, or they can sometimes be executed in the opposite order, which can depend on the functions involved. Each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, may be implemented by a dedicated hardware-based system that performs the specified function or action, or may be implemented by a combination of dedicated hardware and computer instructions.

Claims

1. A battery cell, characterized in that: include: The positive electrode sheet and the negative electrode sheet are stacked, 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 to form an overhang area. The packaging structure is provided in the overhang gap area corresponding to the overhang area. Among them, the packaging structure includes a lithium supplement agent, the lithium supplement agent has ionic conductivity, and the delithiation product of the lithium supplement agent includes a solid product and lithium ions, and the solid product is electronically insulating. The lithium supplement agent has the function of a lithium source and can release lithium ions during the battery charging process.

2. The battery cell according to claim 1, characterized in that The packaging structure is arranged on the circumferential side of the positive electrode sheet corresponding to the overhanging gap area, and the packaging structure and the positive electrode sheet are integrated to form a positive electrode sheet with a packaging structure; or, The packaging structure corresponds to the overhanging gap area and is arranged on the end face of the solid electrolyte layer facing the positive electrode sheet to form a solid electrolyte layer with a packaging structure. The packaging structure is constructed with an interlocking groove, which is adapted to the size of the positive electrode sheet so that the positive electrode sheet can be embedded in the interlocking groove.

3. The battery cell according to claim 2, characterized in that The positive electrode includes: positive electrode current collector layer; A positive electrode active material layer is arranged on the positive electrode current collector layer; The packaging structure is arranged around the circumferential side of the positive electrode active material layer.

4. The battery cell according to claim 3, characterized in that The positive electrode active material layer includes a positive electrode active material, a solid electrolyte, a first conductive agent, and a first binder. The parameters of the positive electrode active material layer include: The weight ratio of the positive electrode active material, the solid electrolyte, the first conductive agent and the first binder is 50-89:10-30:0-10:1-3; or the weight ratio of the positive electrode active material, the solid electrolyte, the first conductive agent and the first binder is 75:20:3:2; and / or The positive electrode active material includes one or more of lithium nickel cobalt aluminum oxide, lithium nickel oxide, lithium sulfide, lithium nickel manganese oxide, lithium manganese oxide, lithium rich manganese base, lithium iron manganese phosphate, lithium cobalt oxide, lithium nickel cobalt manganese oxide and lithium iron phosphate; and / or The first binder includes one or more of PVDF-HFP-diisobutyl ketone, fluoropolymer-isobutyl isobutyrate, fluoropolymer-butyl butyrate, SEBS, SEBS-anisole, and PIB-n-heptane.

5. The battery cell according to any one of claims 1 to 4, characterized in that: The thickness of the package structure is 0.5~20 mm; and / or The lithium supplement includes one or more of Li2MoO3, Li2S, Li2S2, Li2S4, Li2S6, Li5FeO4 and Li2C4O4; and / or The solid electrolyte layer includes one or more of an LPSC-type solid electrolyte, a LISICON-type solid electrolyte, a NASICON-type lithium-ion solid electrolyte, a garnet-type solid electrolyte, a perovskite-type solid electrolyte, a Garnet-type solid electrolyte, a LIPON-type solid electrolyte, a Thio-LiSICON-type solid electrolyte, an Argyrodite-type solid electrolyte, a Halide-type solid electrolyte, a Hydride-type lithium-ion solid electrolyte, an LGPS-type solid electrolyte, a PEO-type solid electrolyte, a PVDF-type solid electrolyte, a PAN-type solid electrolyte, a PMMA-type solid electrolyte, and a PVC-type solid electrolyte.

6. A method for preparing a battery cell according to any one of claims 1 to 5, characterized in that: include: Prepare a positive electrode sheet, a negative electrode sheet and a solid electrolyte layer; wherein the size of the negative electrode sheet is larger than that of the positive electrode sheet on at least one circumferential side, so that the negative electrode sheet has an overhang area; Disposing packaging material on the circumferential side of the positive electrode sheet to obtain a positive electrode sheet having an encapsulated structure; or disposing packaging material on the end surface of the solid electrolyte layer facing the positive electrode sheet to obtain a solid electrolyte layer having an encapsulated structure; wherein the packaging material comprises the lithium supplement agent according to any one of claims 1 to 5, and the packaging structure corresponds to the overhang area; The negative electrode sheet, the solid electrolyte layer and the positive electrode sheet are stacked in this order to obtain a battery cell.

7. The method for preparing a battery cell according to claim 6, wherein: Before providing the packaging material on the end surface of the solid electrolyte layer facing the positive electrode sheet, the method further includes: The solid electrolyte layer is transferred to the negative electrode plate to obtain a negative electrode-solid electrolyte layer composite plate.

8. The method for preparing a battery cell according to claim 6 or 7, wherein: The packaging material is provided on the circumferential side of the positive electrode sheet, including: using a 3D printing method to provide the packaging material on the empty foil area of ​​the positive electrode sheet; or The packaging material is provided on the end surface of the solid electrolyte layer facing the positive electrode piece, comprising: using a 3D printing method to provide the packaging material on the end surface of the solid electrolyte layer facing the positive electrode piece.

9. The method for preparing a battery cell according to claim 8, wherein: 3D printing methods include: Preparing a 3D printing overhang slurry; wherein the 3D printing overhang slurry includes a lithium supplement agent, a second binder, and a solvent; Printing the 3D printed overhang slurry onto the empty foil area of ​​the positive electrode sheet, or printing the 3D printed overhang slurry onto the end surface of the solid electrolyte layer facing the positive electrode sheet; The solidified structure can obtain a positive electrode sheet with a package structure or a solid electrolyte layer with a package structure.

10. A 3D printing overhang slurry, characterized in that: As a packaging material for the packaging structure of the battery cell according to any one of claims 1 to 5, or as a packaging material in the method for preparing the battery cell according to any one of claims 6 to 9; According to the mass percentage, the 3D printing overhang slurry includes: 10%~50% lithium replenisher, 1%~30% second binder and 2%~89% solvent; among them, the lithium replenisher has ion conductivity, and the lithium delithiation product of the lithium replenisher includes solid products and lithium ions, and the solid products are electronically insulating.

11. The 3D printing overhang slurry according to claim 10, characterized in that: The 3D printing overhang slurry has at least one of the following: The 3D printing overhang slurry also includes a dispersant of 0.1% to 4%; and / or The viscosity of the 3D printing overhang slurry is 2000-10000 mPa·s; and / or The fineness of the 3D printing overhang slurry is 5-30 μm; and / or The particle size of the lithium supplement is 20 nm to 10 μm; and / or The mass ratio of the lithium supplement agent to the second binder is 100-0.01; and / or The second binder comprises one or more of polyethylene terephthalate, polyvinyl chloride, hydroxyethyl cellulose, polyisobutylene, polyphenylene ether, polyimide, polyacrylonitrile, polyvinylidene fluoride, polyethylene glycol, polyethylene oxide, hydroxypropyl cellulose, styrene-butadiene rubber, polyacrylic acid, polyvinyl pyrrolidone and polyacrylate; and / or The solvent includes one or more of N-methylpyrrolidone, anisole, polyvinylpyrrolidone, ethanol, toluene, acetonitrile, glycerol and n-heptane.

12. A solid-state battery, characterized in that: include: The battery cell according to any one of claims 1 to 5; or, a battery cell obtained by the method for preparing the battery cell according to any one of claims 6 to 9.

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