All-solid-state battery cell and dry-method electrostatic spraying nozzle and method for preparing all-solid-state battery cell

Abstract

The invention discloses an all-solid-state battery cell and a dry-method electrostatic spraying nozzle and method for preparing the all-solid-state battery cell, the nozzle structure is suitable for a powder spraying technology, the nozzle structure comprises an inner layer structure, a middle layer structure and an outer layer structure, the inner layer and the outer layer can be electrode active material channels, and the middle layer can be a coating layer channel of multiple materials such as a carbon conductive agent, a solid electrolyte and a binder; wherein the middle-layer powder can realize quantitative and uniform coating of the inner-layer electrode active material and the outer-layer electrode active material by virtue of electrostatic adhesion and control of a flow rate ratio, a good electron and ion transport channel is constructed, and the electrochemical performance of the solid-state battery is improved. A solvent is not needed in the preparation process of the all-solid-state battery cell, the design of the nozzle structure can be compatible with integrated preparation of a current collector, an electrode and an electrolyte membrane at the same time, the preparation process is greatly simplified, and the production cost is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy batteries, and particularly relates to an all-solid-state battery cell, a dry electrostatic spraying nozzle for preparing the same, and a method for preparing the same. Background Art

[0002] Currently, liquid lithium batteries mainly use flammable and explosive organic electrolytes, and their potential safety hazards cannot be completely eliminated. All-solid-state battery cells use all-solid electrolytes to replace the flammable and volatile liquid electrolyte components in traditional liquid batteries, and they have outstanding advantages of high safety and high energy density, and are considered to be the most promising next-generation battery technology.

[0003] However, the traditional wet coating process for preparing battery cells cannot solve the problems of chemical compatibility between solvents and solid electrolytes and the contact problem between solid-solid particles in the all-solid-state battery cells caused by solvent volatilization. Currently, combining the characteristics of different electrolytes (mainly including three categories: polymer all-solid-state, sulfide all-solid-state, and oxide ceramic all-solid-state), related patents cover wet / dry electrode preparation technologies (CN117038862A), ceramic-organic composite separator technologies (CN117673442A), sulfide electrolyte membrane technologies (CN118156593A), and spraying preparation electrode process technologies (CN117038862A). Among them, wet electrode preparation is only completed by introducing a certain amount of solid electrolyte filler during the preparation process of traditional liquid battery electrodes, while dry electrode preparation mainly mixes the positive and negative active materials and conductive agents together to form an electrode through the fibrillation of binders and cold / hot pressing processes. The preparation of the separator (electrolyte membrane) is to mix solid electrolyte powder and binder powder and then press them into a membrane under high pressure, and the spraying process completes the preparation of the electrode through wet mixing, electrostatic high-pressure spraying, drying and other processes. It can be seen that the preparation of existing electrodes often focuses on wet coating roll pressing and wet electrostatic spraying technologies, and the separator uses a composite solid electrolyte pressing technology. Among them, the pore structure formed during the drying and volatilization of the solvents required for wet coating roll pressing and wet electrostatic spraying mixing is not conducive to the interfacial contact between the solid electrolyte and the electrode active material, and the use of too much solvent will also increase the preparation cost of the battery cell; although the dry preparation technologies such as dry roll pressing / pressing can greatly solve the problems of solvent compatibility and solid-solid contact, they have new problems such as difficulty in uniformly mixing the conductive agent, solid electrolyte and positive and negative active substances and low roll pressing / pressing efficiency.

[0004] In view of this, the present invention is specifically proposed. Summary of the Invention

[0005] Aiming at the above problems, the main purpose of the present invention is to provide an all-solid-state battery cell, a dry electrostatic spraying nozzle for preparing the same, and a method for preparing the same, which can achieve the preparation of all-solid-state battery cells with rapid dispersion, uniform mixing and coating, high efficiency and low cost through powder atomization mixing, multi-channel orientation, and electrostatic spraying.

[0006] To this end, in the first aspect of the present invention, a dry electrostatic spraying nozzle for preparing an all-solid-state battery cell is proposed. The nozzle includes a three-layer structure of an outer channel, a middle channel, and an inner channel arranged coaxially. Among them, the outer channel and the inner channel are both formed by two electrostatic insulation layers and are respectively used for flowing the first dry powder and the third dry powder; the middle channel is formed by two non-electrostatic insulation layers and is used for flowing the second dry powder; after applying static electricity to the non-electrostatic insulation layer, the second dry powder flowing into the middle channel becomes charged powder, and the charged powder and the uncharged powder, namely the first dry powder and / or the third dry powder, can form a coating material in which the charged powder coats the uncharged powder after being ejected together.

[0007] Furthermore, the middle channel includes n fan-shaped partitions, where n = 1 to 12.

[0008] Furthermore, the outer channel, the middle channel, and the inner channel include at least one of the following conditions:

[0009] The diameter range of the inner channel is 0.1 mm to 1.5 mm;

[0010] The width of the middle channel is 0.01 mm to 1 mm;

[0011] The width of the outer channel is 0.1 mm to 2 mm.

[0012] In the second aspect, a method for preparing an all-solid-state battery cell is proposed. The preparation method is realized by using the nozzle described in the first aspect.

[0013] Furthermore, the preparation method includes the following steps:

[0014] S1. The raw material dry powder of the all-solid-state battery cell is atomized, dispersed, and advanced to flow to the nozzle by the power of compressed air;

[0015] S2. After applying static electricity to the non-electrostatic insulation layer of the nozzle, the ejected raw material dry powder is combined and deposited under the action of static electricity, and forms a material layer of the all-solid-state battery cell after cold pressing or hot pressing.

[0016] Among them, when the ejected raw material dry powder contains both charged powder and uncharged powder at the same time, a coating material in which the charged powder coats the uncharged powder can be formed.

[0017] Even further, the pressure of the compressed air is 100 to 500 kPa;

[0018] and / or, the voltage of the static electricity is 0.1 to 15 kV;

[0019] and / or, the flow rate of the first dry powder is 0.1 to 3 g / min;

[0020] and / or, the flow rate of the second dry powder is 0.005 to 1 g / min;

[0021] and / or, the flow rate of the third dry powder is 0.1 to 5 g / min.

[0022] Furthermore, the particle size of the raw material dry powder satisfies at least one of the following conditions:

[0023] The particle size D50 of the positive electrode active material or the negative electrode active material is 0.5 to 50 μm;

[0024] The particle size D50 of the carbon conductive agent is 0.002 to 50 μm;

[0025] The particle size D50 of the solid electrolyte is 0.1 to 20 μm;

[0026] The particle size D50 of the binder is 0.1 to 600 μm;

[0027] The particle size D50 of the current collector is 0.5 to 50 μm.

[0028] Furthermore, the first dry powder and / or the third dry powder includes one or more dry powders of a current collector, a positive electrode active material, a negative electrode active material, and a solid electrolyte, and the second dry powder includes one or more dry powders of a carbon conductive agent, a solid electrolyte, and a binder.

[0029] Still further, the current collector includes positive electrode aluminum or negative electrode copper;

[0030] and / or, the positive electrode active material includes at least one of a lithium-rich manganese-based material, a nickel cobalt manganese ternary oxide material, a high-voltage lithium nickel manganate material, and a lithium manganate material;

[0031] and / or, the negative electrode active material includes graphite, silicon carbon, or a silicon oxide negative electrode material;

[0032] and / or, the solid electrolyte includes at least one of a fast ion conductor, a garnet oxide, a perovskite material, a sulfide, and a halide;

[0033] and / or, the carbon conductive agent includes at least one of acetylene black, graphene, carbon nanotubes, super conductive carbon black, conductive carbon black, mesophase carbon microspheres, and carbon fibers;

[0034] and / or, the binder includes at least one of polytetrafluoroethylene, polyvinylidene fluoride, polyacrylonitrile, styrene-butadiene rubber, polyvinyl alcohol, polyvinyl butyral, and polyethylene oxide.

[0035] In a third aspect, a all-solid-state battery cell is proposed, and the all-solid-state battery cell is prepared by using the nozzle described in the first aspect or by the preparation method described in the second aspect.

[0036] Compared with the prior art, the present invention has at least the following beneficial effects:

[0037] 1. The nozzle of the present invention has a coaxial three-layer structure and is particularly suitable for powder spraying technology. It can optimize the coating and stacking form between the sprayed electrode active material, carbon conductive agent, and solid electrolyte, and improve the energy density and electrochemical kinetic performance of the battery cell. Specifically, the inner and outer channels can be used as the channels for the electrode active material, while the middle channel can be used as the channel for the coating layer. Further, the channels for different coating materials including carbon conductive agent, solid electrolyte, and binder can be specifically divided by a fan shape. In the case of gas atomizing the powder and feeding it to the nozzle, through the control of electrostatic adhesion and flow rate ratio, the middle-layer powder can quantitatively and uniformly coat the inner and outer electrode active materials, constructing a good electron and ion transport channel, thereby improving the electrochemical performance of the solid-state battery. The nozzle of the present invention can perform dry powder spraying, without the use of solvents, and can also be compatible with the integrated preparation of current collectors, electrodes, and electrolyte membranes, significantly simplifying the preparation process and reducing the production cost.

[0038] 2. The preparation method of the present invention adopts a dry electrostatic spraying process, mainly avoiding the use of solvents in the wet coating process, fundamentally eliminating the formation of electrode pores during the solvent evaporation and drying process and reducing costs; and compared with the dry binder fibrillation drawing and wrapping roller pressing process, it can rely on the strong electrostatic attraction and aggregation between particles to reduce the use of the electron insulator - organic binder, and form a denser electrode layer and electrolyte layer through hot pressing; the spraying process can also be applied to the in-situ preparation of copper / aluminum current collectors.

[0039] 3. The all-solid-state battery of the present invention is integrally formed by dry electrostatic spraying, layer-by-layer pressing and stacking. It has a compact structure, a wide controllable range of layer thickness, good solid-solid interface contact between particles, excellent ion-electron migration kinetics, excellent cycle stability, high stacking efficiency, and can achieve high-voltage output of a single cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0041] Figure 1 It is a schematic diagram of the coaxial nozzle structure;

[0042] Among them: 1 - outer channel, 2 - first middle channel, 3 - second middle channel, 4 - inner channel, 5 - non-electrostatic insulating layer. Detailed implementation manners

[0043] To make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described below in conjunction with embodiments. The embodiments of the present invention are implemented on the premise of the technical solutions of the present invention, and detailed implementation manners and processes are given. Those skilled in the art should understand that the said embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention. The protection scope of the present invention is not limited to the following embodiments either. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0044] In the embodiments of the present invention, the process parameters without specific conditions are usually carried out according to conventional conditions. Unless otherwise specified and / or described, throughout, all numerical values related to the component dosages are "numerical values or ratios of mass". Unless otherwise specified, the raw materials used in the present invention can all be obtained from commercially available products.

[0045] In the present invention, the endpoints and any values of the disclosed ranges are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in the present invention.

[0046] According to the first aspect of the present invention, a dry electrostatic spraying nozzle for preparing an all-solid-state battery cell, as Figure 1 shown, the nozzle includes three-layer structures of an outer layer channel 1, a middle layer channel, and an inner layer channel 4 set coaxially. Among them, both the outer layer channel 1 and the inner layer channel 4 are formed by two electrostatic insulating layers and are respectively used for flowing first dry powder and third dry powder; the middle layer channel is formed by two non-electrostatic insulating layers 5 and is used for flowing second dry powder; after applying static electricity on the non-electrostatic insulating layer 5, the second dry powder flowing into the middle layer channel becomes charged powder, and after being sprayed out together with the uncharged powder, that is, the first dry powder and / or the third dry powder, a coating material in which the charged powder coats the uncharged powder can be formed.

[0047] The nozzle of the present invention can, during the dry powder electrostatic spraying process, when compressed air atomizes and disperses the powder material into single or tiny particles, uniformly adsorb these particles onto the surface of the target device through the selective action of an electrostatic field to form a uniform coating. Specifically, due to the coaxial design of the nozzle, by applying static electricity to the middle layer and not applying static electricity to the outer and inner layers, the dry powder ejected from the three-layer channel or two-layer channel forms a coating material through electrostatic action. That is, the second dry powder flowing into the middle layer channel becomes charged powder, and after being ejected together with the uncharged powder, namely the first dry powder and / or the third dry powder, a coating material in which the charged powder coats the uncharged powder can be formed, that is, the coating material in which the second dry powder coats the first dry powder, the coating material in which the second dry powder coats the third dry powder, and the mixture of the coating material in which the second dry powder coats the first dry powder and the coating material in which the second dry powder coats the third dry powder. When the types of dry powder are different, a multi-component coating material with a core-shell structure can be formed, which can achieve specific mixing between different functional powder materials, including the core-shell coating and bonding of binders, carbon conductive agents, and solid electrolytes to electrode main materials such as NCM / SiC in the electrode active layer. When the materials of the first dry powder, the second dry powder, and the third dry powder are the same, a single-component coating material with layer-by-layer coating can also be formed. Particularly, in the nozzle of the present invention, the channel where static electricity is applied is set as the middle layer, and the channels where no static electricity is applied are set as the inner and outer layers, which can enable the uncharged powder in the inner and outer layers to be coated by the charged powder passing through the middle layer at a short distance. Compared with the setting of a single inner layer channel or outer layer channel without applying static electricity, it can enable the material to be coated to be dispersed through the inner and outer double channels, with more uniform dispersion, which is more convenient for the material to be dispersed into particles and then all be coated, and can also improve the coating efficiency. Generally, starting from the performance of all-solid-state batteries, in the preparation of all-solid-state batteries, the inner and outer layers of the nozzle of the present invention are channels for electrode active materials, and the middle layer is a coating layer channel for multi-materials such as carbon conductive agents, solid electrolytes, and binders with multiple sector partitions.

[0048] As an alternative embodiment of the nozzle of the present invention, the middle layer channel includes n sector partitions, where n = 1 to 12; when n ≠ 1, the middle layer channel includes a first middle layer channel 2 and a second middle layer channel 3; preferably, n ≥ 3, and the middle layer channel includes sector partitions of carbon conductive agent powder, solid electrolyte powder, and binder powder.

[0049] As an alternative embodiment of the nozzle of the present invention, the outer layer channel 1, the middle layer channel, and the inner layer channel 4 include at least one of the following conditions:

[0050] The diameter range of the inner layer channel 4 is r 1 = 0.1 mm to 1.5 mm (such as 0.2 mm, 0.4 mm, 0.6 mm, 0.8 mm, 1.0 mm, 1.2 mm, 1.4 mm, etc.);

[0051] The width d of the middle layer channel1 = r 2 - r 1 = 0.01 mm to 1 mm (such as 0.05 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, etc.), r 2 is the outer diameter of the middle layer channel;

[0052] The width d of the outer layer channel 1 2 = r 3 - r 2 = 0.1 mm to 2 mm (such as 0.2 mm, 0.4 mm, 0.6 mm, 0.8 mm, 1.0 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, etc.), r 3 is the outer diameter of the outer layer channel.

[0053] According to the second aspect of the present invention, a method for preparing an all-solid-state battery cell, the preparation method is realized by using the nozzle described in the first aspect.

[0054] The nozzle structure described in the first aspect of the present invention is adapted to the dry electrostatic spraying technology, which uses compressed air power to atomize, disperse and propel the powder to spray out; since the inner layer and the outer layer channels of the nozzle are provided with electrostatic insulation layers, only the middle layer channel and the target device for spraying, i.e., the receiver, can apply static electricity, so that the atomized powder in each channel of the middle layer channel or its fan-shaped area is negatively charged after being applied with static electricity, and will spontaneously adsorb to the uncharged powder, i.e., the neutral powder, ejected from the inner layer and the outer layer channels after spraying under the action of electrostatic induction interaction, forming a uniform coating effect of negatively charged powder coating neutral powder. The solid electrolyte and carbon conductive agent that do not form a coating structure can also play a role in filling the stacking holes. Therefore, as an optional implementation manner of the preparation method of the present invention, the preparation method includes the following steps: S1. The raw material dry powder of the all-solid-state battery cell is atomized, dispersed and propelled to flow through the nozzle by using the power of compressed air; S2. After applying static electricity to the non-electrostatic insulation layer of the nozzle, the ejected raw material dry powder is combined and deposited under the action of static electricity, and forms the material layer of the all-solid-state battery cell after cold pressing or hot pressing.

[0055] Wherein, when the ejected raw material dry powder contains both charged powder and uncharged powder, a coating material of charged powder coating uncharged powder can be formed.

[0056] In the present invention, the raw material dry powders used in the process of preparing the all-solid-state battery cell, such as carbon conductive agents, binders, solid electrolytes, and electrode active materials, are not particularly limited, and existing ones can be used. The coaxial function of the nozzle is mainly intended to achieve the coating of the carbon conductive agent, solid electrolyte, and binder on the electrode active material particles. Therefore, as an optional implementation manner of the preparation method of the present invention, the first dry powder and / or the third dry powder include one or more dry powders of current collectors, positive electrode active materials, negative electrode active materials, and solid electrolytes, and the second dry powder includes one or more of carbon conductive agents, solid electrolytes, and binders. Further, the current collector includes positive electrode aluminum or negative electrode copper; the positive electrode active material includes lithium-rich manganese-based materials, nickel cobalt manganese ternary oxide materials, high-voltage lithium nickel manganate materials, and lithium manganate materials; the negative electrode active material includes graphite, silicon-carbon, or silicon-oxygen negative electrode materials; the solid electrolyte includes fast ion conductors (Li 1.4 Al 0.4 Ti 1.6 (PO 4 ) 3 、Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 ), garnet oxides (Li 7 La 3 Zr 2 O 12 ), perovskite materials (Li 0.35 La 0.55 TiO 3 ), sulfides (Li 7 P 3 S 11 、Li 6 PS 5 Cl、Li 10 GeP 2 S 12 、Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 ), and halides (Li 3 YCl 6 、Li 3 YBr 6 、Li 3 InCl 6 、Li 3 ErCl 6 ) of at least one kind.

[0057] In addition, in the present invention, the carbon conductive agent includes at least one of acetylene black (AB), graphene, carbon nanotube (CNT), super conductive carbon black (SP), conductive carbon black (KB), mesocarbon microbeads (MCMB), and carbon fiber (CNF);

[0058] and / or, the binder includes at least one of polytetrafluoroethylene, polyvinylidene fluoride, polyacrylonitrile, styrene-butadiene rubber, polyvinyl alcohol, polyvinyl butyral, and polyethylene oxide.

[0059] In the present invention, the receiver is preferably a plate (receiving plate) to facilitate the layering of the received powder. Specifically, the charged and uncharged dry powders are adsorbed and combined with each other by electrostatic interaction, and are jointly sprayed onto the receiving plate to neutralize the static electricity, and at the same time form a thin layer, and then a dense electrode layer and other material layers can be formed by cold / hot pressing. Through the preparation method of the present invention, the negative current collector layer, negative active layer, solid electrolyte layer, positive active layer, and positive current collector layer in the all-solid-state battery cell can be obtained. Further, the positive and negative active layers can be a mixed layer of electrode active materials (such as NCM, SiC, graphite, etc.), solid electrolyte, carbon conductive agent, and binder; the electrolyte layer can be a solid electrolyte layer mixed with a binder.

[0060] As an alternative embodiment of the preparation method of the present invention, the pressure P of the compressed air is 100 - 500 kPa (such as 150 kPa, 200 kPa, 250 kPa, 300 kPa, 350 kPa, 400 kPa, 450 kPa, etc.);

[0061] and / or, the voltage E of the static electricity is 0.1 - 15 kV (such as 0.5 kV, 1 kV, 3 kV, 5 kV, 7 kV, 9 kV, etc.);

[0062] and / or, the flow rate v of the third dry powder 1 = 0.1 - 5 g / min (such as 0.5 g / min, 1 g / min, 1.5 g / min, 2 g / min, 2.5 g / min, 3 g / min, 3.5 g / min, 4 g / min, 4.5 g / min, etc.), and further is 2 - 2.5 g / min;

[0063] and / or, the flow rate v of the second dry powder 2 = 0.005 - 1 g / min (such as 0.01 g / min, 0.05 g / min, 0.07 g / min, 0.09 g / min, 0.11 g / min, 0.13 g / min, 0.15 g / min, 0.17 g / min, 0.19 g / min, etc.), and further is 0.005 - 0.5 g / min;

[0064] and / or, the flow rate v of the first dry powder 3 = 0.1 - 3 g / min (such as 0.2 g / min, 0.4 g / min, 0.6 g / min, 0.8 g / min, 1 g / min, 1.2 g / min, 1.4 g / min, 1.6 g / min, 1.8 g / min, 2 g / min, 2.2 g / min, 2.4 g / min, 2.6 g / min, 2.8 g / min, etc.), further 2 - 2.5 g / min.

[0065] The dry electrostatic spraying preparation method of the present invention is very different from the wet electrospinning process; the former realizes powder-air mixing and atomization by means of compressed air flow, and then drives the atomized particles to spray out through the air flow thrust. The nozzle diameter is large, the production line process efficiency is high, the required electrostatic voltage is low, and the energy consumption is low; while the latter relies on ultra-high voltage electrostatic drive and high-viscosity fluid to draw wire at the ultra-fine needle tip to achieve the wire-making effect. Whether the Taylor cone is formed at the nozzle determines the success or failure of electrospinning, and this is closely related to the ultra-high voltage electrostatic parameters and the nozzle diameter. Therefore, the nozzle of the present invention and the nozzle used in wet electrospinning cannot be directly interchanged and applied.

[0066] In the present invention, the powder flow rates in the inner, middle, and outer channels of the nozzle can be the same or different, and the specific control can be achieved through existing technologies. For example, the external connections of the three channels are high-pressure gas pipelines of three branches, and the air flow can be easily controlled through valves. In addition, the feeding flow rate of the powder into the atomization area can also be controlled; the control of the air flow rate and the powder feeding flow rate, the combination adjustment of these two rates can achieve the specified atomization and dispersion effect and spraying efficiency; and the air flow rates and the powder feeding rates of the three channels can all be controlled through separate valves; when the dry powder flow rates of the three channels are controlled to be different, different ratios of the electrode active material / carbon conductive agent / binder / solid electrolyte can be achieved.

[0067] As an optional implementation manner of the preparation method of the present invention, the particle size of the raw material dry powder satisfies at least one of the following conditions:

[0068] The particle size D50 of the positive electrode active material or the negative electrode active material is 0.5 - 50 μm (such as 1 μm, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 45 μm, 49 μm, etc.), further 1 - 30 μm, and even further 2 - 15 μm;

[0069] The particle size D50 of the carbon conductive agent is 0.002 - 50 μm (such as 0.01 μm, 0.1 μm, 1 μm, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 45 μm, 49 μm, etc.), further 0.01 - 0.1 μm;

[0070] The particle size D50 of the solid electrolyte is 0.1 to 20 μm (such as 0.5 μm, 1 μm, 3 μm, 5 μm, 7 μm, 9 μm, 11 μm, 13 μm, 15 μm, 17 μm, 19 μm, etc.), and further is 0.5 to 2 μm;

[0071] The particle size D50 of the binder is 0.1 to 600 μm (such as 1 μm, 5 μm, 10 μm, 50 μm, 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, 550 μm, etc.), and further is 0.2 to 0.5 μm;

[0072] The particle size D50 of the current collector is 0.5 to 50 μm (such as 1 μm, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 45 μm, 49 μm, etc.), and further is 10 to 15 μm.

[0073] In the above technical solution, the particle size of the electrode active material mainly affects the rate performance of the battery, that is, the performance of fast charging and fast discharging. For the particle sizes of the conductive agent, solid electrolyte, binder, and current collector, their influences are mainly divided into two aspects: one is the physical strength of each spray coating, and the other is the coating effect of each auxiliary material on the main material. The performance varies with the relative particle size and content matching; the spraying and coating with small sizes have good contact.

[0074] According to the third aspect of the present invention, a all-solid-state battery cell is provided, and the all-solid-state battery cell is prepared by using the nozzle described in the first aspect or by the preparation method described in the second aspect.

[0075] Further, the all-solid-state battery cell includes a positive current collector layer, a positive active layer, an electrolyte layer, a negative active layer, and a negative current collector layer. The battery cell is formed by sequentially spraying and hot pressing each layer and then stacking them. The specific method is as follows: the raw material dry powder of the all-solid-state battery cell is atomized, dispersed, and advanced through the power of compressed air and flows to the nozzle. Among them, the current collector powder, as the second dry powder, flows to the middle channel to become charged powder, combines and deposits under the action of static electricity, and forms the current collector layer of the all-solid-state battery cell after hot pressing. When the current collector powder is copper powder, the current collector layer is the negative current collector layer; when the current collector powder is aluminum powder, the current collector layer is the positive current collector layer;

[0076] The electrode active powder flows as the first dry powder and / or the third dry powder into the outer channel and / or the inner channel to become uncharged powder, and the carbon conductive agent, the solid electrolyte, and the binder flow as the second powder into the middle channel to become charged powder. After they are ejected together, under the action of static electricity, a coating material in which the carbon conductive agent, the solid electrolyte, and the binder coat the electrode active powder is formed, and at the same time, it is deposited under the action of static electricity. After hot pressing, an electrode active layer of the all-solid-state battery cell is formed. When the electrode active powder is the positive electrode active powder, the electrode active layer is the positive electrode active (mixed) layer; when the electrode active powder is the negative electrode active powder, the electrode active layer is the negative electrode active (mixed) layer;

[0077] The electrolyte powder flows as the second dry powder into the middle channel to become charged powder, combines and deposits under the action of static electricity, and forms the solid electrolyte layer of the all-solid-state battery cell after hot pressing; the binder powder can also be ejected together with the electrolyte powder as the second powder, and finally a solid electrolyte layer in which the electrolyte and the binder are mixed is formed.

[0078] In addition, since the electrode coating and the electrolyte coating have a significantly increased density after cold / hot pressing, the contact and conductivity between the powder particles can be significantly improved.

[0079] Moreover, the positive electrode active layer is formed by a material in which the carbon conductive agent, the solid electrolyte, and the binder coat the positive electrode active material; the negative electrode active layer is formed by a material in which the carbon conductive agent, the solid electrolyte, and the binder coat the negative electrode active material. This uniform coating can enhance the electronic conductivity and ionic conductivity of the surface interfaces of the positive and negative electrode active materials.

[0080] The present invention will be further described in detail below with reference to specific embodiments.

[0081] The specific materials and raw materials used in the following examples and comparative examples are as follows:

[0082] Copper metal powder, that is, copper powder, D50 = 10 μm, purchased from Jiangxi Copper;

[0083] Polytetrafluoroethylene binder powder, D50 = 0.3 μm, purchased from Chemours;

[0084] Silicon oxide powder (a negative electrode material of silicon monoxide type, abbreviated as SiO negative electrode), D50 = 7 μm, purchased from Bosai Lis;

[0085] Graphite powder, D50 = 12 μm, purchased from Shanshan Technology;

[0086] Sulfide solid electrolyte powder: Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 , D50 = 1 μm, purchased from Ganfeng Lithium;

[0087] Superconductive carbon black (SP), D50 = 0.05 μm, purchased from Timcal, Switzerland;

[0088] Ternary polycrystal (nickel-cobalt-manganese ternary polycrystalline oxide), D50 = 15 μm, purchased from Rongbai Technology;

[0089] Ternary single crystal (nickel-cobalt-manganese ternary single crystal oxide), D50 = 2 μm, purchased from Dongsheng Technology;

[0090] Aluminum metal powder, namely aluminum powder, D50 = 15 μm, purchased from Laipeng;

[0091] Lithium nickel manganate high-voltage material, D50 = 12 μm, purchased from Dongsheng Technology;

[0092] Perovskite material, Li 0.35 La 0.55 TiO 3 , D50 = 0.5 μm, purchased from Hengli New Materials;

[0093] Butadiene rubber binder, D50 = 0.2 μm, purchased from Shanhaichem;

[0094] Example 1:

[0095] An all-solid-state battery cell and its dry electrostatic spraying nozzle and method for preparation. The nozzle is as Figure 1 shown, including three-layer structure of an outer layer channel 1, a middle layer channel and an inner layer channel 4 set coaxially. Among them, both the outer layer channel 1 and the inner layer channel 4 are formed by two electrostatic insulation layers, and the middle layer channel is formed by two non-electrostatic insulation layers 5. The middle layer channel includes n fan-shaped partitions, n > 3, at least including a first middle layer channel 2 and a second middle layer channel 3. Among them, the diameter range r 1 of the inner layer channel 4 = 1.5 mm, and the width d 1 of the first middle layer channel 2 and the second middle layer channel 3 = r 2 -r 1 = 0.5 mm, r 2 is the outer diameter of the middle layer channel, and the width d 2 of the outer layer channel 1 = r 3 -r 2 = 0.5 mm.

[0096] Using the aforementioned nozzle, compressed air (pressure 0.5 MPa) is used as the power to atomize, disperse and propel and eject each material powder to prepare an all-solid-state battery cell. The specific method includes the following steps:

[0097] (1) Spraying and forming of the negative electrode current collector layer: Copper powder and polytetrafluoroethylene binder powder are uniformly mixed in a mass ratio of 99:1 and injected into a fluidized powder barrel. Then, they are introduced into the atomization chamber of the middle layer channel through an air flow pipeline, and a 5 kV electrostatic charge is applied to the surface of the powder particles. Then, they are uniformly ejected through the middle layer channel of the nozzle at a powder flow rate of 0.1 g / min, and a 2-μm ultra-thin copper layer current collector is deposited and hot-pressed on a metal copper foil base plate, that is, the negative electrode current collector layer;

[0098] (2) Spraying and forming of the negative electrode active layer: Silicon oxide powder and graphite powder are uniformly mixed in a mass ratio of 35:65 to form silicon oxide-graphite powder and injected into a fluidized powder barrel. They are introduced into the atomization chambers of the inner layer and the outer layer channels through an air flow pipeline, and then uniformly ejected through the inner layer and the outer layer channels of the nozzle at a powder flow rate of 2 g / min. At the same time, sulfide solid electrolyte powder, polytetrafluoroethylene binder powder, and SP are respectively introduced into different atomization chambers of the middle layer channel through an air flow pipeline, and a 5 kV electrostatic charge is applied to the surface of the powder particles. Then, they are ejected simultaneously through each fan-shaped partition in the middle layer channel of the nozzle, such as the first middle layer channel 2, the second middle layer channel 3, and the first middle layer channel 2, etc., at powder flow rates of 0.5 g / min, 0.06 g / min, and 0.04 g / min respectively. The charged sulfide solid electrolyte, carbon conductive agent, and binder powder will spontaneously combine with the neutral silicon oxide-graphite powder in the air to complete the uniform coating of the main electrode active material, and are directionally deposited on the copper layer current collector obtained in step (1). After hot pressing, a negative electrode active layer with a thickness of 120 μm is obtained;

[0099] (3) Spraying and forming of the electrolyte layer: Sulfide solid electrolyte powder and polytetrafluoroethylene binder powder are uniformly mixed in a mass ratio of 98:2 and injected into a fluidized powder barrel. They are introduced into the atomization chamber of the middle layer channel through an air flow pipeline, and a 5 kV electrostatic charge is applied to the surface of the powder particles. Then, they are uniformly ejected through the middle layer channel of the nozzle at a powder flow rate of 1 g / min, and are directionally deposited on the negative electrode active layer obtained in step (2). After hot pressing, a solid electrolyte layer with a thickness of 20 μm is obtained;

[0100] (4) Spraying and forming of the positive electrode active layer: Ternary polycrystal and ternary single crystal are uniformly mixed in a mass ratio of 75:25 and injected into a fluidized powder barrel. Other process parameters are the same as those of the negative electrode active layer spraying and forming process. Finally, they are directionally deposited on the solid electrolyte layer obtained in step (3), and after hot pressing, a positive electrode active layer with a thickness of 150 μm is obtained;

[0101] (5) Spraying and forming of the positive electrode current collector layer: Aluminum powder and polytetrafluoroethylene binder powder are uniformly mixed in a mass ratio of 99:1 and injected into a fluidized powder barrel. Other process parameters are the same as those of the negative electrode current collector layer spraying and forming process. Finally, they are directionally deposited on the positive electrode active layer obtained in step (4), and after hot pressing, a 4-μm ultra-thin aluminum layer current collector is obtained, that is, the positive electrode current collector layer;

[0102] (6) On the positive current collector layer obtained in step (5), continue to spray the negative current collector layer, and successively fabricate the second-layer battery cell according to the above steps, and a total of 5 times of battery cell layer fabrication are completed; finally, positive and negative electrode tabs are led out from the upper and lower surfaces of the stacked battery cell.

[0103] Example 2:

[0104] The difference between this example and Example 1 is only that in each layer of the battery cell: the thickness of the positive active layer is controlled at about 300 μm, the thickness of the negative active layer is controlled at about 240 μm, the thickness of the solid electrolyte layer is controlled at 8 μm, and other preparation process parameters are the same as those in Example 1.

[0105] Example 3:

[0106] The difference between this example and Example 1 is only that in each layer of the battery cell: the active powder used in the positive active layer is a lithium nickel manganate high-voltage material with D50 = 12 μm, and other preparation process parameters are the same as those in Example 1.

[0107] Example 4:

[0108] The difference between this example and Example 1 is only that in the solid electrolytes used in the negative active layer, the solid electrolyte layer and the positive active layer, perovskite materials (Li 0.35 La 0.55 TiO 3 ) are used. The thickness of the positive active layer is controlled at about 75 μm, the thickness of the negative active layer is controlled at about 60 μm, the thickness of the solid electrolyte layer is controlled at 4 μm, and other preparation process parameters are the same as those in Example 1.

[0109] Example 5:

[0110] The difference between this example and Example 1 is only that in the spraying process of the negative active layer and the positive active layer, the inner and outer channels of the nozzle eject evenly at a powder flow rate of 1.8 g / min; in each fan-shaped partition in the middle channel of the nozzle, such as the first middle channel 2, the second middle channel 3, and the first middle channel 2 arranged at intervals, eject simultaneously at powder flow rates of 0.5 g / min (solid electrolyte powder), 0.06 g / min (binder powder), and 0.065 g / min (carbon conductive agent) respectively, and other preparation process parameters are the same as those in Example 1.

[0111] Comparative Example 1:

[0112] This comparative example is a comparative experiment of Example 1. The only difference from Example 1 is that the preparation of the negative electrode active layer and the positive electrode active layer is carried out by electrostatic spraying molding in a single nozzle mode, that is: using a conventional single-channel nozzle that can apply static electricity or using any one of the first middle channels 2 or the second middle channels 3 in each fan-shaped partition in the middle channel of the nozzle of the present invention to apply 5 kV static electricity to the premixed and atomized active main material, carbon conductive agent, solid electrolyte and binder and spray it out at a powder flow rate of 2 g / min. The electrode active main material, carbon conductive agent, solid electrolyte and binder powders, all of which are charged with each other, collide with each other in the air and cannot form a structure in which the electrode active main material is evenly coated, and are directly deposited directionally on the previously formed layer to obtain the positive / negative electrode active layer. Other preparation process parameters are the same as those in Example 1.

[0113] Comparative Example 2:

[0114] This comparative example is a comparative experiment of Example 2. The traditional wet coating process is adopted, and the negative electrode active layer, the positive electrode active layer and the electrolyte layer are all prepared by the wet method, specifically as follows:

[0115] Preparation of the negative electrode active layer: Mix silicon oxide powder and graphite powder evenly according to a mass ratio of 35:65 as the negative electrode active main material powder, and then mix the negative electrode active main material powder, Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 , butadiene rubber binder and SP are mixed according to a mass ratio of 2:0.5:0.06:0.04, and dissolved in an ethanol dispersion solvent, and homogenized to obtain a negative electrode slurry with a solid content of 43%. Then, the negative electrode slurry is coated on a commercially available copper foil with a thickness of 6 μm, and after drying, die-cutting and other steps, the preparation of the negative electrode active layer with a thickness of 120 μm is completed to obtain a negative electrode sheet;

[0116] Preparation of the positive electrode active layer: Mix ternary polycrystal and ternary single crystal evenly according to a mass ratio of 75:25 as the positive electrode active main material powder, and then mix the positive electrode active main material powder, Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 , butadiene rubber binder and SP are mixed according to a mass ratio of 2:0.5:0.06:0.04, and dissolved in an ethanol dispersion solvent, and homogenized to obtain a positive electrode slurry with a solid content of 65%. Then, the positive electrode slurry is coated on a commercially available aluminum foil with a thickness of 12 μm, and after drying, die-cutting and other steps, the preparation of the positive electrode active layer with a thickness of 150 μm is completed to obtain a positive electrode sheet;

[0117] Preparation of the electrolyte layer: The sulfide solid electrolyte (Li 9.54 Si 1.74 P1.44 S 11.7 Cl 0.3 ) The powder and polytetrafluoroethylene binder powder are uniformly mixed at a mass ratio of 98:2, dissolved in an ethanol dispersion solvent, and homogenized to obtain an electrolyte slurry with a solid content of 24%. Then, a wet coating and drying and film peeling process are carried out to complete the preparation of an electrolyte (membrane) layer with a thickness of about 12 μm. Then, the positive and negative electrode sheets and the electrolyte membrane are wound / layered and encapsulated to complete the preparation of the battery cell.

[0118] Comparative Example 3:

[0119] This comparative example is a comparative experiment of Example 2, and is prepared by a dry rolling process. Specifically, the negative / positive current collectors use industrial 6-μm copper foil and 12-μm aluminum foil respectively;

[0120] The electrolyte layer, through Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 The powder and polytetrafluoroethylene binder powder with D50 = 500 μm are uniformly mixed at a mass ratio of 98:2, and are formed into a film through processes such as shearing (drawing), kneading, and rolling, with a film thickness of about 60 μm;

[0121] The negative active layer is formed by mixing silicon oxide powder and graphite powder at a mass ratio of 35:65, and then sequentially mixing with Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 polytetrafluoroethylene binder powder and SP at a mass ratio of 2:0.5:0.06:0.04, and are formed into a film through processes such as shearing, kneading, and rolling, with a film thickness of about 240 μm;

[0122] The positive active layer uses ternary polycrystalline and ternary single-crystalline positive active powder materials uniformly mixed at a mass ratio of 75:25 as the main positive active powder. Then, the main positive active powder, Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 polytetrafluoroethylene binder and carbon conductive agent are sequentially mixed at a mass ratio of 2:0.5:0.06:0.04, and are formed into a film through processes such as shearing, kneading, and rolling, with a film thickness of about 300 μm;

[0123] The positive active layer is roll-pressed and adhered to the positive aluminum current collector, and the negative active layer is roll-pressed and adhered to the negative copper current collector. Finally, the positive and negative electrodes and the separator are cut, layered, and hot-pressed to complete the production of the battery cell.

[0124] Testing and Results

[0125] The cells obtained in Examples 1-5 and Comparative Examples 1-3 were tested as follows:

[0126] 1. Positive / negative current collector thickness test: Conducted using a micrometer.

[0127] 2. Positive active layer / negative active layer / electrolyte layer thickness test: Quantitatively determined by SEM cross-section scanning or X-ray-CT.

[0128] 3. First-cycle Coulombic efficiency (first efficiency) and cycle capacity retention rate test of the cell: Charge and discharge were carried out at a rate of 0.1C.

[0129] The above test results are shown in Table 1:

[0130] Table 1. Performance comparison of all-solid-state cells prepared in Examples 1-5 and Comparative Examples 1-3

[0131]

[0132] As can be seen from Table 1, compared with Comparative Example 1, the powder electrostatic spraying with a multi-nozzle structure design can achieve a better dispersion effect of the main material and the auxiliary material. Through the effective coating of the active main material by the carbon conductive agent, the binder and the solid electrolyte powder, the first charge-discharge efficiency and cycle stability of the battery cell can be improved; compared with Comparative Example 2, the electrostatic powder spraying can easily realize the preparation of thick electrodes and thin electrolyte layers, while the traditional wet mixing and coating method has limitations in the preparation process of the thickness of the positive and negative active layers; compared with Comparative Example 3, the electrostatic powder spraying can achieve a more uniform mixing and coating through the atomization treatment of the powder particles, while the dry powder mixing and rolling process (dry binder fiberization and wire drawing wrapping and rolling process) has problems of uneven physical mixing, and is significantly lower than the electrostatic powder spraying process in terms of the Coulomb efficiency and cycle stability in the first week of charge and discharge; Examples 3 and 4 prove that this electrostatic powder spraying process can be applied to many positive and negative electrode materials and electrolyte materials. Among them, since the positive electrode material in Example 3 belongs to a super-high voltage material, there is a slightly mismatched electrochemical window when matching with the sulfide solid electrolyte at high voltage, resulting in a lower efficiency and a slightly faster performance decay; Example 4 is a thickness ultra-thin design made in combination with the low ionic conductivity and insufficient ion transfer kinetics of the current oxide solid electrolyte. Due to the use of an electrolyte with a relatively low conductivity, the preparation thickness of the electrode sheet and the electrolyte membrane and the charge-discharge rate will be significantly lower, which is a normal situation in the current industry; compared with Example 1, it can be seen from Example 5 that by freely and independently adjusting the ratio of the active main material, the solid electrolyte, the carbon conductive agent, and the binder through the multi-nozzle structure, the electrical performance of the battery cell can be optimized. The relative content ratios of the active main material, the solid electrolyte, the carbon conductive agent, and the adhesive in Example 5 are 85.3%, 11.9%, 1.4%, and 1.4% respectively; while the relative content ratios of the active main material, the solid electrolyte, the carbon conductive agent, and the adhesive in Example 1 are 87%, 10.8%, 0.9%, and 1.3% respectively; the increase in the capacity retention rate of Example 5 compared with Example 1 mainly comes from the increase in the content of the solid electrolyte and the carbon conductive agent, maintaining the ion and electron conduction network during the charge and discharge process of the battery.

[0133] In addition, comparing Examples 1-5 with Comparative Examples 2-3, it can be seen that electrostatic powder spraying can also achieve precise control of the thickness of ultra-thin positive / negative current collectors, breaking through the limitations of traditional rolling current collector technology. Among them, the comparison between Comparative Example 2 and Example 2 focuses on the difference in thickness control ability caused by different processes. Among them, the main positive and negative materials (ternary polycrystalline single crystal composite, silicon-oxygen graphite composite) and carbon conductive agent (SP) in Comparative Example 2 are the same as those in Example 2. However, due to the different dry and wet processes, the selected binders, their dissolution characteristics and binding mechanisms are different. In addition, the thickness of the current collector is different, and there is a difference in the current collection direction. These differences caused by different processes all have an impact on the performance. For example, the internal cell layers of the stacked cell are in a series mode, and the single cell voltage is high; while the internal cell layers of traditional wound and laminated cells are in a parallel mode, and the single cell capacity is high; there is also a significant difference in the current-carrying capacity of the current collectors of the two. Under the same size, the current-carrying capacity of the current collector of the stacked cell is much greater than that of the current collector of the laminated / wound cell. The fundamental reason is the difference in the current collection direction.

[0134] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A dry electrostatic spray nozzle for preparing all-solid-state battery cells, characterized in that: The nozzle comprises a three-layer structure of a coaxially set outer channel (1), a middle channel and an inner channel (4), wherein the outer channel (1) and the inner channel (4) are both formed by two electrostatic insulating layers, and are used to circulate the first dry powder and the third dry powder respectively; the middle channel is formed by two non-electrostatic insulating layers (5), and is used to circulate the second dry powder; after static electricity is applied to the non-electrostatic insulating layer (5), the second dry powder circulated to the middle channel becomes a charged powder, and after being sprayed out together with the uncharged powder, i.e., the first dry powder and / or the third dry powder, a coating material in which the charged powder coats the uncharged powder can be formed.

2. The nozzle according to claim 1, characterized in that: The middle-level channel includes n sector-shaped partitions, where n=1-12.

3. The nozzle according to claim 1, characterized in that: The outer channel (1), the middle channel and the inner channel (4) include at least one of the following conditions: The diameter of the inner channel (4) ranges from 0.1 mm to 1.5 mm; The width of the middle channel is 0.01 mm to 1 mm; The width of the outer channel (1) is 0.1 mm to 2 mm.

4. A method for preparing an all-solid-state battery cell, characterized in that: The preparation method is achieved by using the nozzle described in any one of claims 1-3.

5. The preparation method according to claim 4, characterized in that: The following steps are involved: S1. The raw material dry powder of the all-solid-state battery cell is atomized and dispersed by compressed air and is pushed to flow to the nozzle; S2, after applying static electricity to the non-static insulating layer of the nozzle, the ejected raw material dry powder is combined and deposited under the action of static electricity, and is cold pressed or hot pressed to form a material layer of the all-solid-state battery core, When the sprayed raw material dry powder contains both charged powder and uncharged powder, a coating material in which the charged powder covers the uncharged powder can be formed.

6. The preparation method according to claim 5, characterized in that: The pressure of the compressed air is 100-500 kPa; And / or, the voltage of the static electricity is 0.1 to 15 kV; and / or, the flow rate of the first dry powder is 0.1 to 3 g / min; and / or, the flow rate of the second dry powder is 0.005 to 1 g / min; And / or, the flow rate of the third dry powder is 0.1-5 g / min.

7. The preparation method according to claim 5, characterized in that: The particle size of the raw material dry powder at least meets at least one of the following conditions: The particle size of the positive electrode active material or the negative electrode active material is D50=0.5-50 μm; The particle size of the carbon conductive agent is D50 = 0.002 to 50 μm; The particle size of the solid electrolyte is D50 = 0.1 to 20 μm; The particle size of the binder is D50 = 0.1 to 600 μm; The particle size of the current collector is D50 = 0.5 to 50 μm.

8. The preparation method according to claim 5, characterized in that: The first dry powder and / or the third dry powder include one or more dry powders of a current collector, a positive electrode active material, a negative electrode active material and a solid electrolyte, and the second dry powder includes one or more dry powders of a carbon conductive agent, a solid electrolyte and a binder.

9. The preparation method according to claim 8, characterized in that: The current collector includes positive electrode aluminum or negative electrode copper; And / or, the positive electrode active material includes at least one of a lithium-rich manganese-based material, a nickel-cobalt-manganese ternary oxide material, a nickel-manganese-lithium high-voltage material, and a lithium manganese-oxide material; And / or, the negative electrode active material includes graphite, silicon carbon or silicon oxygen negative electrode material; and / or, the solid electrolyte comprises at least one of a fast ion conductor, a garnet oxide, a perovskite material, a sulfide and a halide; And / or, the carbon conductive agent includes at least one of acetylene black, graphene, carbon nanotubes, super conductive carbon black, conductive carbon black, mesophase carbon microspheres and carbon fibers; And / or, the binder includes at least one of polytetrafluoroethylene, polyvinylidene fluoride, polyacrylonitrile, styrene-butadiene rubber, polyvinyl alcohol, polyvinyl butyral and polyethylene oxide.

10. An all-solid-state battery cell, characterized in that: The all-solid-state battery cell is prepared using the nozzle described in any one of claims 1 to 3 or by the preparation method described in any one of claims 4 to 9.

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