Solid-state battery and manufacturing method therefor, negative electrode sheet, and electric device

Abstract

The present application provides a solid-state battery and a manufacturing method therefor, a negative electrode sheet, and an electric device, and further relates to a negative-electrode-free solid-state battery. The solid-state battery comprises a negative electrode current collector, a second carbon layer, a first carbon layer, a solid electrolyte layer, and a positive electrode layer that are sequentially stacked; the second carbon layer comprises a second carbon material, and the first carbon layer comprises a first carbon material; the pore volume fraction of the second carbon material is low; the ion diffusion coefficient and / or pore volume fraction of the first carbon material is greater than that of the second carbon material; at least one of the Dv50 and average particle size of the second carbon material is less than that of the first carbon material; further, the first carbon material is a porous material.

Description

Solid-state batteries, their preparation methods, negative electrode sheets, and electrical devices

[0001] Related applications

[0002] This application claims priority to Chinese patent application CN2024119974339, filed on December 31, 2024, entitled "Solid-state battery and preparation method thereof, negative electrode sheet and electrical device thereof", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of solid-state battery technology, further to a negative electrode-free solid-state battery, and even further to a solid-state battery and its preparation method, negative electrode sheet, and electrical device. Background Technology

[0004] The statements herein are provided only as background information in connection with this application and do not necessarily constitute prior art.

[0005] Solid-state batteries possess immense potential for application due to their advantages such as high energy density, high power, and high safety. Among them, electrodeless solid-state batteries, as a novel battery system, initially store all active ions in the positive electrode active material. Taking lithium ions as an example, during charging, lithium ions are extracted from the positive electrode, migrate to the negative electrode, and directly electrodeposit on the negative electrode current collector to form lithium metal. During subsequent discharge, the lithium metal loses electrons and converts back to lithium ions, which then migrate to the positive electrode and embed into the crystal lattice of the positive electrode active material. Electrodeless solid-state batteries exhibit extremely high energy densities, such as exceeding 500 Wh / kg. However, the non-uniformity of lithium deposition, and the resulting issues of cycle stability and battery reliability, limit the practical application of electrodeless solid-state batteries. Summary of the Invention

[0006] According to various embodiments and examples of this application, this application provides a solid-state battery and its preparation method, a negative electrode sheet, and an electrical device, wherein the solid-state battery can be a negative electrode-free solid-state battery. This solid-state battery has a long cycle life.

[0007] In a first aspect of this application, a solid-state battery is provided, comprising a negative electrode current collector, a second carbon layer, a first carbon layer, a solid electrolyte layer, and a positive electrode layer sequentially stacked. The second carbon layer comprises a second carbon material, and the first carbon layer comprises a first carbon material. The second carbon material has a very low pore volume fraction. The ion diffusion coefficient and / or pore volume fraction of the first carbon material is greater than that of the second carbon material. The second carbon material has a D... vAt least one of the particle size and average particle size is smaller than that of the first carbon material. Furthermore, the first carbon material is a porous material. This solid-state battery exhibits a long cycle life and good battery reliability.

[0008] In some embodiments, the pore volume fraction of the second carbon material is ≤5%.

[0009] In this application, the “pore volume fraction” of a material refers to the percentage of the total pore volume in the particles relative to the particle volume.

[0010] In some embodiments, a solid-state battery is provided, comprising a negative electrode current collector, a second carbon layer, a first carbon layer, a solid electrolyte layer, and a positive electrode layer sequentially stacked. The second carbon layer comprises a second carbon material, and the first carbon layer comprises a first carbon material. The first carbon material is a porous carbon material, and the pore volume fraction of the second carbon material is less than or equal to 5%. At least one of the ion diffusion coefficient and the pore volume fraction of the first carbon material is greater than that of the second carbon material. The D0 of the second carbon material is... v At least one of 50 and average particle size is smaller than the first carbon material.

[0011] In this solid-state battery, due to factors such as energy, kinetics, and solid-phase interface characteristics, the storage of active ions at the negative electrode is mainly through direct deposition on the negative electrode current collector. This solid-state battery comprises a second carbon layer, including a second carbon material, and a first carbon layer, including a first carbon material, sequentially disposed between the negative electrode current collector and the solid electrolyte layer. The first carbon material near the solid electrolyte layer is a porous carbon material with a high lithium-ion diffusion coefficient and / or a high pore volume fraction, providing abundant interfaces and a good electrolyte-first carbon layer interface. This allows the first carbon layer to quickly attract and mediate the rapid transport of active ions to the negative electrode current collector. The second carbon material near the negative electrode current collector has no obvious pore structure (corresponding to a very low pore volume fraction) and a low particle size, forming a dense and flat second carbon layer. This provides a good negative electrode current collector-second carbon layer interface, which is beneficial for inducing uniform deposition of active ions at the negative electrode current collector. Based on the aforementioned multiple effects, through multi-level interface optimization between the solid electrolyte layer-first carbon layer-second carbon layer-negative electrode current collector, the deposition behavior of active ions can be optimized, significantly suppressing local deposition and deposition inhomogeneity at the negative electrode, and significantly suppressing dendrite formation at the negative electrode. Therefore, the cycle life of the solid-state battery can be significantly extended.

[0012] It is understandable that by suppressing the formation of dendrites on the negative electrode, short circuits in the battery can also be suppressed, thereby improving the reliability of solid-state batteries.

[0013] In some embodiments, the first carbon material and the second carbon material satisfy one or more of the following characteristics:

[0014] (a1) The ion diffusion coefficient of the first carbon material is greater than or equal to 1×10⁻⁶ -9 cm 2 / s, optional 1×10 -9 cm 2 / s~5×10 -9 cm 2 / s;

[0015] (a2) The ion diffusion coefficient of the second carbon material is greater than or equal to 1×10⁻⁶. -10 cm 2 / s, optional 1×10 -10 cm 2 / s~1×10 -9 cm 2 / s.

[0016] In some embodiments, the first carbon material and the second carbon material satisfy one or more of the following characteristics:

[0017] (a1') The ion diffusion coefficient of the first carbon material is 2 × 10⁻⁶ -9 cm 2 / s~5×10 -9 cm 2 / s;

[0018] (a2') The ion diffusion coefficient of the second carbon material is 2 × 10⁻⁶. -10 cm 2 / s~8×10 -10 cm 2 / s.

[0019] By controlling the ion diffusion coefficient of the first carbon material within the aforementioned range, and / or by controlling the first carbon material to have a higher ion diffusion coefficient than the aforementioned ion diffusion coefficient of the second carbon material, the ability of the first carbon layer to rapidly conduct active ions can be improved, which is beneficial for better mediating the rapid transport of active ions to the negative electrode current collector and for better suppressing the formation of dendrites on the negative electrode.

[0020] By better suppressing dendrite formation on the negative electrode, it is beneficial to extend the cycle life of solid-state batteries.

[0021] It is understandable that by improving the ability of the first carbon layer to rapidly conduct active ions, the initial coulombic efficiency can also be improved, battery kinetics can be enhanced, and battery rate performance can be optimized.

[0022] By controlling the transport kinetics of the first carbon layer, solid-state battery cells can maintain high discharge capacity even at high current densities, thus enabling them to achieve good rate performance. Furthermore, by controlling the transport kinetics of the first carbon layer, active ions can be more easily deposited and stripped at the negative electrode, thereby reducing capacity decay during cycling and improving the cycle stability of the solid-state battery.

[0023] By increasing the ion diffusion coefficients of the first and second carbon materials, the number of active ions adsorbed in the porous carbon can be reduced, thereby allowing more active ions to be deposited on the surface of the negative electrode current collector and improving the first coulombic efficiency of the solid-state battery.

[0024] In some embodiments, the first carbon layer and the second carbon layer satisfy one or more of the following characteristics:

[0025] (b1) The first carbon material includes one or more of hard carbon, soft carbon, artificial graphite and natural graphite;

[0026] (b2) The second carbon material includes one or more of carbon black, carbon nanotubes, graphene and fullerene;

[0027] (b3) The second carbon material includes a doping element, which includes one or more of silver, tin, copper, silicon, magnesium and zinc; optionally, the doping element is in the form of one or more of elemental, carbon alloy and oxide.

[0028] (b4) The second carbon material is a non-porous carbon material;

[0029] (b5) The mass percentage of the first carbon material in the first carbon layer is greater than or equal to 90%, and can be selected as 90% to 98%;

[0030] (b6) The mass percentage of the second carbon material in the second carbon layer is greater than or equal to 90%, and can be selected as 90% to 98%.

[0031] In some embodiments, the first carbon layer and the second carbon layer satisfy one or more of the following characteristics:

[0032] (b1') The total mass of hard carbon, soft carbon, artificial graphite and natural graphite accounts for 80% to 100% of the mass of the first carbon material;

[0033] (b2') The total mass of carbon black, carbon nanotubes, graphene and fullerene accounts for 80% to 100% of the mass of the second carbon material;

[0034] (b5') The mass percentage of the first carbon material in the first carbon layer is 95% to 98%;

[0035] (b6') The mass percentage of the second carbon material in the second carbon layer is 95% to 98%.

[0036] By controlling the first carbon material to include the aforementioned porous carbon materials, such as one or more of hard carbon, soft carbon, artificial graphite and natural graphite, abundant interfaces can be provided, which can quickly conduct active ions. This enables the first carbon layer to quickly attract and mediate the rapid transport of active ions to the negative electrode current collector, which is beneficial to better suppress the formation of dendrites on the negative electrode.

[0037] By controlling the second carbon material to include one or more of the aforementioned non-porous carbon materials, such as carbon black, carbon nanotubes, graphene, and fullerene, a dense and flat surface can be formed, which is more conducive to inducing the uniform deposition of active ions on the negative electrode current collector and is more conducive to better suppressing the formation of dendrites on the negative electrode.

[0038] In some embodiments, the first carbon material includes a porous structure, and the first carbon material satisfies one or more of the following characteristics:

[0039] (c1) The pore volume fraction of the first carbon material is greater than or equal to 25%, optionally 30% to 60%, and further optionally 35% to 55%;

[0040] (c2) The pore volume of the first carbon material is greater than or equal to 0.1 cm³. 3 / g, can be selected as 0.1cm 3 / g~0.5cm 3 / g; where, the pore volume of the material refers to the ratio of the total pore volume in the particles to the mass of the particles;

[0041] (c3) The pore structure in the first carbon material includes mesopores and micropores, wherein the diameter of the mesopores is 2m to 50nm and the diameter of the micropores is less than 2nm.

[0042] In some embodiments, the pore structure in the first carbon material includes mesopores and micropores, and the first carbon material satisfies one or more of the following characteristics:

[0043] (d1) The mesopores account for 5% to 50% of the total number of pores in the pore structure;

[0044] (d2) The number of micropores in the pore structure accounts for 10% to 80%.

[0045] In some embodiments, the first carbon material satisfies one or more of the following characteristics:

[0046] (d1') The mesopores account for 10% to 40% of the total number of pores in the pore structure;

[0047] (d2') The number of micropores in the pore structure accounts for 10% to 65%.

[0048] By controlling one or two parameters of the pore volume fraction and pore volume of the first carbon material within the aforementioned range, it is beneficial to provide a richer interface for the first carbon layer, to enhance the ability of the first carbon layer to rapidly conduct active ions, to promote the rapid attraction and mediation of active ions to the negative electrode current collector by the first carbon layer, and to suppress the formation of dendrites on the negative electrode; in addition, the structural strength of the first carbon material can also be taken into account.

[0049] The pore volume fraction reflects the richness of the pore structure. By controlling the pore volume fraction and / or pore volume of the first carbon material within the aforementioned range, on the one hand, a higher total amount of micropores and mesopores and fewer macropores can be achieved, providing a rich pore structure that is conducive to the rapid transport of active ions to the surface of the negative electrode current collector; on the other hand, the first carbon material can also have good structural strength, which can better withstand the volume changes caused by the deposition of active metals and better suppress the volume expansion of the negative electrode.

[0050] Mesopores and micropores can increase the specific surface area of ​​the first carbon material, which is beneficial for providing better channels for the diffusion of active ions inside the first carbon material, and is conducive to further improving the active ion transport rate of the first carbon material.

[0051] By controlling the proportion of mesopores and / or micropores in the pore structure within the aforementioned range, it is beneficial to provide a richer surface interface for the first carbon layer, to enhance the ability of the first carbon layer to rapidly conduct active ions, to promote the rapid attraction and mediation of active ions to the negative electrode current collector by the first carbon layer, and to suppress the formation of dendrites on the negative electrode.

[0052] The first carbon material D v 50 is denoted as D v 501, the first carbon material D v 90 is written as D v 901, the D of the first carbon material v 10 is denoted as D v 101, the SPAN value of the first carbon material is denoted as SPAN1, SPAN1 = (D v 901-D v 101) / D v 501.

[0053] In some embodiments, the first carbon material satisfies one or more of the following characteristics:

[0054] (e1) D of the first carbon material v50 or an average particle size of 50 nm to 2 μm, optionally 500 nm to 2 μm, and further optionally 500 nm to 1.5 μm;

[0055] (e2) The first carbon material satisfies SPAN1 of 1.5 to 4, and can be selected as 1.5 to 2;

[0056] (e3) The specific surface area of ​​the first carbon material is 50m² 2 / g~500m 2 / g, optional 300m 2 / g~500m 2 / g;

[0057] (e4) The compaction density of the first carbon material powder under a pressure of 5 tons is 0.75 g / cm³. 3 ~0.9g / cm 3 .

[0058] By controlling the specific surface area of ​​the first carbon material within the aforementioned range, the larger specific surface area of ​​porous carbon can promote the rapid transport of lithium ions to the surface of the negative electrode current collector, improve the ion transport kinetics of the negative electrode, and reduce the adsorption of lithium ions in the porous carbon.

[0059] By controlling the D of the first carbon material v 50. One or more of the parameters among SPAN1, specific surface area and powder compaction density under 5 tons of pressure, within the aforementioned range, can adjust the packing density of the first carbon material, which is beneficial to make the first carbon layer have a more suitable porosity, more suitable for rapid conduction of active ions, more conducive to the first carbon layer to rapidly attract and mediate the rapid transport of active ions to the negative electrode current collector, and more conducive to suppressing the formation of dendrites on the negative electrode.

[0060] In some embodiments, the second carbon material satisfies one or more of the following characteristics:

[0061] (f1) The average diameter of the primary particles in the second carbon material is 20 nm to 100 nm, and can be selected as 20 nm to 80 nm;

[0062] (f2) The specific surface area of ​​the second carbon material is 25m². 2 / g~50m 2 / g, optional 40m 2 / g~50m 2 / g;

[0063] (f3) The compaction density of the second carbon material powder under a pressure of 5 tons is 0.7 g / cm³. 3 ~0.9g / cm 3 ;

[0064] (f4) The pore volume fraction of the second carbon material is less than 5%, which can be selected as 0 to 1%, and more preferably less than 1%.

[0065] By controlling one or more of the following parameters within the aforementioned range: the average diameter of the primary particles in the second carbon material, the specific surface area of ​​the second carbon material, and the compaction density of the powder under 5 tons of pressure in the second carbon material, the packing density of the second carbon material can be adjusted. This is beneficial for making the second carbon layer denser and smoother, for inducing more uniform deposition of active ions on the negative electrode current collector, and for suppressing dendrite formation on the negative electrode.

[0066] By controlling the pore volume fraction of the second carbon material within a low range, it is beneficial to make the second carbon layer denser and smoother.

[0067] In some embodiments, the solid-state battery satisfies one or more of the following characteristics:

[0068] (g1) The thickness of the first carbon layer is 2μm to 8μm;

[0069] (g2) The thickness of the second carbon layer is 2μm to 8μm;

[0070] (g3) The thickness ratio of the first carbon layer to the second carbon layer is 5:1 to 1:5.

[0071] In some embodiments, the solid-state battery satisfies one or more of the following characteristics:

[0072] (g1') The thickness of the first carbon layer is 2.5 μm to 7.5 μm;

[0073] (g2') The thickness of the second carbon layer is 2.5 μm to 7.5 μm;

[0074] (g3') The thickness ratio of the first carbon layer to the second carbon layer is 3:1 to 1:3;

[0075] (g4') The sum of the thicknesses of the first carbon layer and the second carbon layer is 5 μm to 15 μm.

[0076] By controlling the thickness of the first carbon layer within the aforementioned range, it is beneficial to better leverage the role of the first carbon layer in rapidly attracting and mediating the rapid transport of active ions, and to better suppress the formation of dendrites on the negative electrode.

[0077] By controlling the thickness of the second carbon layer within the aforementioned range, it is beneficial to better leverage the role of the second carbon layer in inducing the uniform deposition of active ions on the negative electrode current collector, and to better suppress the formation of dendrites on the negative electrode.

[0078] By controlling the thickness ratio of the first carbon layer to the second carbon layer within the aforementioned range, it is beneficial to enable the first carbon layer and the second carbon layer to work together better, to better balance the rapid transport of active ions to the negative electrode current collector and the uniform deposition on the negative electrode current collector, and to better suppress the formation of dendrites on the negative electrode.

[0079] By controlling the sum of the thicknesses of the first carbon layer and the second carbon layer within the aforementioned range, the active ion transport distance between the solid electrolyte layer and the negative electrode current collector can be controlled within a more suitable range, which is beneficial for improving the initial coulombic efficiency, battery kinetics, and battery rate performance.

[0080] In some embodiments, the solid-state battery satisfies one or more of the following characteristics:

[0081] (h1) The first carbon layer includes a first adhesive;

[0082] (h2) The second carbon layer includes a second binder.

[0083] By setting a binder in the first carbon layer, it is beneficial to improve the electrical contact network between the first carbon materials, to better leverage the role of the first carbon layer in mediating the rapid transport of active ions, and to better suppress the formation of dendrites on the negative electrode.

[0084] By setting a binder in the second carbon layer, it is beneficial to make the second carbon layer denser and flatter, which is beneficial to induce active ions to deposit more uniformly on the negative electrode current collector and to suppress dendrite formation on the negative electrode.

[0085] In some embodiments, the solid-state battery satisfies one or more of the following characteristics:

[0086] (h1') The first carbon layer includes a first adhesive, which includes one or more of polyvinylidene fluoride, polyacrylic acid, styrene-butadiene rubber and carboxymethyl cellulose;

[0087] (h2') The second carbon layer includes a second adhesive, which includes one or more of polyvinylidene fluoride, polyacrylic acid, styrene-butadiene rubber and carboxymethyl cellulose;

[0088] (h3') The mass percentage of the first adhesive in the first carbon layer is 2% to 10%, and can be selected as 2% to 5%;

[0089] (h4') The second adhesive has a mass percentage content of 2% to 10% in the second carbon layer, and can be selected as 2% to 5%.

[0090] By controlling the mass percentage of the first binder in the first carbon layer within the aforementioned range, it is beneficial to better balance the effect of the rapidly active ions of the first carbon material and the bonding effect of the first binder.

[0091] By controlling the mass percentage of the second binder in the second carbon layer within the aforementioned range, it is beneficial to better balance the density and smoothness of the second carbon layer and the electrical conductivity of the second carbon material.

[0092] In some embodiments, the negative current collector includes one or more of copper, stainless steel, nickel, titanium, aluminum, and alloys composed of at least two of copper, stainless steel, nickel, titanium, and aluminum.

[0093] The type of negative electrode current collector can be flexibly selected.

[0094] In some embodiments, the solid-state battery is a negative electrode-free solid-state battery.

[0095] In some embodiments, the solid electrolyte layer comprises a solid electrolyte material and a third binder. This facilitates the formation of large-size solid electrolyte films, leading to the fabrication of large-size batteries.

[0096] In some embodiments, the solid-state battery satisfies one or both of the following characteristics:

[0097] (i1) The mass percentage of the third binder in the solid electrolyte layer is denoted as f. E Satisfying 0 <f E ≤5%;

[0098] (i2) The third adhesive includes polytetrafluoroethylene, wherein the polytetrafluoroethylene accounts for 80% to 100% of the mass of the third adhesive.

[0099] By controlling the mass percentage (f) of the third binder in the solid electrolyte layer E Within the aforementioned range, it is beneficial to better utilize the ability of the solid electrolyte layer to rapidly conduct active ions.

[0100] By controlling the third binder, including polytetrafluoroethylene (PTFE), it is beneficial to improve the chemical compatibility between the solid electrolyte material and the binder components in the solid electrolyte layer, which is more conducive to the chemical stability of the solid electrolyte layer and the efficiency and stability of its ability to conduct active ions.

[0101] In addition, PTFE can be rapidly fiberized under shear force. Fiberized PTFE can provide more bonding force between solid electrolyte particles, giving the solid electrolyte layer extremely high mechanical strength and making it less prone to cracking during densification. This can improve the processability of the solid electrolyte layer and solid-state battery.

[0102] In some embodiments, the positive electrode layer includes a positive electrode active layer, which comprises one or more of lithium transition metal oxide positive electrode materials and lithium phosphate positive electrode materials.

[0103] The type of positive electrode active material in the positive electrode active layer can be flexibly selected according to the battery performance requirements.

[0104] In some embodiments, the solid-state battery satisfies one or both of the following characteristics:

[0105] (j1) The solid-state battery is a lithium-ion solid-state battery;

[0106] (j2) The solid-state battery is an all-solid-state battery.

[0107] In a second aspect of this application, a negative electrode sheet is provided, comprising a negative current collector, a second carbon layer and a first carbon layer stacked sequentially, wherein the second carbon layer comprises a second carbon material and the first carbon layer comprises a first carbon material;

[0108] Wherein, the first carbon material is a porous carbon material; the pore volume fraction of the second carbon material is less than or equal to 5%; at least one of the ion diffusion coefficient and the pore volume fraction of the first carbon material is greater than that of the second carbon material; the D of the second carbon material... v At least one of 50 and average particle size is smaller than the first carbon material; the pore volume fraction of the material refers to the percentage of the total pore volume in the particles relative to the particle volume.

[0109] This negative electrode sheet allows for the sequential placement of a second carbon layer comprising a second carbon material and a first carbon layer comprising a first carbon material between the negative electrode current collector and the solid electrolyte layer in a solid-state battery. The first carbon material near the solid electrolyte layer is a porous carbon material with a high lithium-ion diffusion coefficient and / or a high pore volume fraction, providing abundant interfaces and a good electrolyte-first carbon layer interface. This allows the first carbon layer to quickly attract and mediate the rapid transport of active ions to the negative electrode current collector. The second carbon material near the negative current collector has no obvious pore structure (corresponding to a very low pore volume fraction) and a low particle size, forming a dense and flat second carbon layer. This provides a good negative electrode current collector-second carbon layer interface, which is beneficial for inducing uniform deposition of active ions at the negative electrode current collector. Based on the aforementioned multiple effects, through multi-level interface optimization between the solid electrolyte layer-first carbon layer-second carbon layer-negative electrode current collector, the deposition behavior of active ions can be optimized, significantly suppressing local deposition and deposition inhomogeneity of the negative electrode, and significantly suppressing dendrite formation in the negative electrode. Therefore, the cycle life of the solid-state battery can be significantly extended.

[0110] It is understandable that by suppressing the formation of dendrites on the negative electrode, short circuits in the battery can also be suppressed, thereby improving the reliability of solid-state batteries.

[0111] In some embodiments, the negative electrode sheet satisfies one or both of the following characteristics:

[0112] (k1) The negative electrode current collector includes the features of the negative electrode current collector in the solid-state battery described in the first aspect of this application;

[0113] (k2) The second carbon layer includes the features of the second carbon layer in the solid-state battery described in the first aspect of this application;

[0114] (k3) The first carbon layer includes the features of the first carbon layer in the solid-state battery described in the first aspect of this application.

[0115] In a third aspect of this application, a method for preparing a solid-state battery is provided, comprising the following steps:

[0116] A positive electrode, a solid electrolyte membrane, and a negative electrode are sequentially stacked to prepare a laminate. The solid electrolyte membrane comprises a solid electrolyte material, and the negative electrode comprises a negative current collector, a second carbon layer, and a first carbon layer sequentially stacked, with the second carbon layer located between the first carbon layer and the solid electrolyte membrane. The second carbon layer comprises a second carbon material, and the first carbon layer comprises a first carbon material. The first carbon material is a porous carbon material. The pore volume fraction of the second carbon material is less than or equal to 5%. At least one of the ion diffusion coefficient and the pore volume fraction of the first carbon material is greater than that of the second carbon material. The D0 of the second carbon material is... v50 and at least one of the average particle size is smaller than the first carbon material; the pore volume fraction of the material refers to the percentage of the total pore volume in the particles relative to the particle volume;

[0117] The solid-state battery is prepared by densifying the laminate under heating conditions.

[0118] In some embodiments, the method for preparing the solid-state battery satisfies one or more of the following characteristics:

[0119] (m1) The negative electrode sheet is prepared by a method including the following steps: coating a second negative electrode slurry including the second carbon material onto at least one side surface of the negative electrode current collector, drying it, and forming a second carbon layer on at least one side surface of the negative electrode current collector; coating a first negative electrode slurry including the first carbon material onto the second carbon layer, drying it, and forming a first carbon layer on the second carbon layer;

[0120] (m2) The negative electrode sheet is the negative electrode sheet described in the second aspect of this application;

[0121] The heating conditions for (m3) are 50℃~100℃;

[0122] (m4) The pressure for the densification treatment is 300MPa to 600MPa.

[0123] After densification treatment, the solid-solid interface contact quality in the overall structure of solid-state batteries can be improved. This can not only improve the solid-solid interface between different structural layers and form a good contact between the positive electrode layer, solid electrolyte layer, first carbon layer, second carbon layer and negative electrode current collector, but also improve the solid-solid interface between solid particles in each structural layer, including the solid-solid interface between the first carbon materials in the first carbon layer and the solid-solid interface between the second carbon materials in the second carbon layer.

[0124] In some embodiments, the solid-state battery preparation method produces the solid-state battery described in the first aspect of this application.

[0125] In a fourth aspect of this application, an electrical device is provided, comprising at least one of the solid-state battery described in the first aspect of this application, the negative electrode sheet described in the second aspect of this application, and a solid-state battery prepared by the method for preparing a solid-state battery described in the third aspect of this application.

[0126] Details of one or more embodiments or examples of this application are set forth in the following drawings and description. Other features, objects, and advantages of this application will become apparent from the specification, drawings, and claims. Attached Figure Description

[0127] To better describe and illustrate the embodiments, examples, or models provided in this application, reference may be made to one or more accompanying drawings. Additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the disclosed applications, the currently described embodiments, examples, or models, or the best mode of conduct of these applications as currently understood. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0128] Figure 1 is a schematic diagram of the structure of a solid-state battery according to an embodiment of the present application. The solid-state battery includes a negative electrode current collector, a second carbon layer, a first carbon layer, a solid electrolyte layer and a positive electrode layer stacked in sequence.

[0129] Figure 2 is a schematic diagram of a solid-state battery cell according to an embodiment of this application.

[0130] Figure 3 is an exploded view of a solid-state battery cell according to an embodiment of this application shown in Figure 1.

[0131] Figure 4 is a schematic diagram of a battery device according to an embodiment of this application.

[0132] Figure 5 is a schematic diagram of a battery pack according to one embodiment of this application.

[0133] Figure 6 is an exploded view of the battery pack of one embodiment of this application shown in Figure 5.

[0134] Figure 7 is a schematic diagram of an electrical device using a solid-state battery as a power source according to an embodiment of this application.

[0135] Figure 8 is a scanning electron microscope (SEM) image of the second carbon material used in one embodiment of this application. The second carbon material is acetylene black.

[0136] Figure 9 is a transmission electron microscope (TEM) image of the second carbon material used in one embodiment of this application. The second carbon material is acetylene black.

[0137] Explanation of reference numerals in the attached drawings: 130, negative current collector; 120, second carbon layer; 110, first carbon layer; 200, solid electrolyte layer; 300, positive electrode layer; 1, battery pack; 2, upper casing; 3, lower casing; 4, battery assembly; 5, solid-state battery cell; 51, casing; 52, solid-state cell; 53, cover plate; 6, electrical device. Detailed Implementation

[0138] The following describes in detail, with appropriate reference to the accompanying drawings, some embodiments of the solid-state battery and its preparation method, negative electrode sheet, and electrical device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0139] The "range" disclosed in this application can be defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints. Any endpoint can be included or excluded independently and can be combined arbitrarily; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​1 and 2 are listed, and maximum range values ​​3, 4, and 5 are also listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0" and "5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when describing a parameter as an integer ≥ 2, it is equivalent to listing integers such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, and 12 for that parameter. For instance, when describing a parameter as an integer selected from "2-10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0140] In this application, the term "numerical value" includes the number itself and its reasonable approximations. The definition of "numerical value" can apply to discrete numerical points or to the endpoints of a numerical range. Unless otherwise specified, the term "approximation" covers a numerical interval based on a reasonable range of fluctuations of the number itself. This reasonable range of fluctuations can vary depending on the type and magnitude of the number. This reasonable range of fluctuations can be reasonably determined based on the accuracy of the testing or measurement method. Therefore, when referring to a numerical value or a numerical range, unless otherwise specified, it should be understood that the numerical value includes its reasonable approximation, and the numerical range includes reasonable approximations at both endpoints. Those skilled in the art will understand that acceptable fluctuation ranges of the relevant approximations can be included within the definition of the numerical value or the numerical range. In this application, unless otherwise specified, "N1" can be reasonably understood as "about N1," and "N1~N2" can be reasonably understood as "about N1 to about N2," where N1 and N2 are two unequal numerical values.

[0141] In this application, unless otherwise specified, "about" means within a reasonable range above and below the stated number, and the range of fluctuation may vary depending on the type and value of the stated number. For example, a range of ±10%, ±5%, ±2%, ±1%, etc., may be allowed. For example, taking "about 20°C" and its approximation as ±1°C, approximate values ​​such as 19°C, 19.5°C, etc., within the approximation range indicated by "about 20°C" should also be included in the range indicated by "about 20°C".

[0142] In this application, the terms "multiple," "various," "multiple items," "several," etc., unless otherwise specified, refer to a quantity greater than or equal to 2. For example, "one or more" means one or more (greater than or equal to) two. It can be understood that when "any number of" items are involved, it refers to any suitable combination of multiple items, that is, a combination of "any number of" items in a manner that does not conflict and enables the implementation of this application.

[0143] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0144] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments. The term "implementation" as used herein has a similar understanding.

[0145] Those skilled in the art will understand that, unless otherwise specified, the order in which the steps are written in the various embodiments or methods of this application does not imply a strict execution order and does not constitute any limitation on the implementation process. The detailed execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps of this application may be performed sequentially or randomly, but are preferably performed sequentially. For example, if method M includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, method M may also include step (c), meaning that step (c) can be added to method M in any order. For example, method M may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0146] In this application, open-ended technical features or solutions described using terms such as "containing," "comprising," or "including" do not exclude additional members beyond those listed unless otherwise specified. They can be considered as providing both closed-ended features or solutions comprised of the listed members and open-ended features or solutions that include additional members beyond the listed members. For example, if 'a' includes a1, a2, and a3, it may also include other members or exclude additional members unless otherwise specified. This can be considered as providing both features or solutions where "a consists of a1, a2, and a3" or "a is selected from a1, a2, and a3," and features or solutions where "a includes not only a1, a2, and a3, but also other members."

[0147] In this application, unless otherwise specified, M (e.g., m1) means that m1 is a non-limiting example of M, and it is understood that M is not limited to m1.

[0148] In this application, "optionally," "optionally," and "optional" mean that something is optional, that is, it is selected from either "with" or "without." If multiple "options" appear in a technical solution, unless otherwise specified and there are no contradictions or mutual constraints, each "option" is independent. Unless otherwise specified, the descriptions such as "optionally include" and "optionally contain" in this application, taking "optionally include" as an example, mean "may include or not include."

[0149] In this application, unless otherwise specified, the features or solutions corresponding to "and / or" include any one of two or more of the related listed items, as well as any and all combinations of the related listed items. Any and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "M and / or N" represents the group consisting of M, N, and "a combination of M and N". "Containing M and / or N" can mean "containing M, containing N, and containing both M and N", or "containing M, containing N, or containing both M and N", and can be appropriately understood according to the context.

[0150] The terms “combinations of,” “any combination of,” and “any combination of” used in this article include all suitable combinations of any two or more of the listed items.

[0151] In this document, the term "suitable" in phrases such as "suitable combination," "suitable method," and "any suitable method" refers to the technical solution that enables the implementation of this application.

[0152] In this document, terms such as "preferred," "better," "more suitable," "ideal," "good," and "superior" are merely descriptions of more effective implementation methods or embodiments, and should be understood not to limit the scope of protection of this application. If multiple "preferred" terms appear in a technical solution, unless otherwise specified and there are no contradictions or mutual constraints, each "preferred" term shall be independent.

[0153] In this application, terms such as "further," "even more," "especially," "for example," "as," "example," and "exemplary" are used for descriptive purposes to indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0154] In this application, the terms "first aspect," "second aspect," "third aspect," "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," "fourth," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on quantity.

[0155] In this application, unless otherwise expressly specified and limited, the phrase "above" or "below" the second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. In this application, unless otherwise expressly specified and limited, the phrase "above" or "below" the second feature can indicate a horizontal positional relationship, or it can simply indicate the existence of an attachment relationship without specifying a horizontal positional relationship.

[0156] In this application, the term "room temperature" generally refers to 4℃ to 35℃, and may refer to 20℃ ± 5℃. In some embodiments or examples of this application, room temperature refers to 20℃ to 30℃.

[0157] In this application, if the unit for a data range is only followed by the right endpoint, it indicates that the units for the left and right endpoints are the same. For example, 3~5h or 3-5h both mean that the unit for the left endpoint "3" and the right endpoint "5" is h (hours), and both have the same meaning as 3h~5h. Furthermore, similar descriptions of other parameters such as temperature and size are interpreted in the same way.

[0158] In this application, the exemplary descriptions such as "in some implementations (or embodiments)" and "in one implementation (or embodiment)" may cover, but are not limited to, the following meanings: these solutions can be combined with other solutions in a suitable manner to form new technical solutions.

[0159] Unless otherwise stated, the improvements described in this application are not intended to be limited to any theoretical constraints.

[0160] For any test method for a certain parameter described in this application, as long as the test result of at least one test method is within the described range, it can be included in the protection scope of this application.

[0161] In electrodeless solid-state batteries, the non-uniformity of lithium deposition leads to issues such as cycle stability and battery reliability, hindering their practical application. Taking lithium ions as the active ion, during charging and discharging, lithium tends to deposit unevenly on the negative electrode current collector, forming lithium dendrites. This results in rapid lithium ion consumption, severely impacting the battery's cycle life and affecting capacity utilization. Reduced capacity utilization, in turn, affects the battery's actual energy density. Furthermore, with increasing cycle count, the continuously growing lithium dendrites can easily cause short circuits, leading to battery failure and decreased battery reliability.

[0162] According to various embodiments and examples of this application, this application provides a solid-state battery and its preparation method, a negative electrode sheet, and an electrical device, wherein the solid-state battery can be a negative electrode-free solid-state battery. This solid-state battery exhibits significantly improved cycle life.

[0163] In some embodiments, the solid-state battery includes a negative electrode current collector 130, a second carbon layer 120, a first carbon layer 110, a solid electrolyte layer 200, and a positive electrode layer 300, which are stacked sequentially. See Figure 1.

[0164] In some embodiments, a solid-state battery is provided, comprising a negative electrode current collector, a second carbon layer, a first carbon layer, a solid electrolyte layer, and a positive electrode layer sequentially stacked. The second carbon layer comprises a second carbon material, and the first carbon layer comprises a first carbon material. The first carbon material is a porous material, and the second carbon material has a very low pore volume fraction. The ion diffusion coefficient and / or pore volume fraction of the first carbon material is greater than that of the second carbon material. The D0 of the second carbon material is... v At least one of the particle size and average particle size is smaller than that of the first carbon material. This solid-state battery exhibits significantly extended cycle life, as well as improved battery reliability.

[0165] In this application, "layered arrangement" refers to the description of the stacking direction between layered structures. For example, "including structural layer A and structural layer B in a layered arrangement" means that the stacking direction of structural layer A and structural layer B is along their respective layer thickness directions, that is, the thickness direction of structural layer A and the thickness direction of structural layer B are the same or substantially the same.

[0166] In this application, the terms "first" and "second" in "first carbon layer," "second carbon layer," "first carbon material," and "second carbon material" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features.

[0167] Unless otherwise stated, the term "solid-state battery" as used in this application refers to a battery in which the electrolyte includes a solid electrolyte material.

[0168] In this solid-state battery, the storage of active ions at the negative electrode is mainly through direct deposition on the negative electrode current collector. The solid electrolyte layer acts as a conductor between the positive electrode layer and the negative electrode current collector, and also isolates the positive electrode layer from the negative electrode current collector, thus preventing short circuits between the positive and negative electrodes. Taking lithium ions as an example, during charging, lithium ions are released from the positive electrode, migrate through the solid electrolyte layer to the negative electrode, and are directly electrodeposited on the negative electrode current collector to form lithium metal. During subsequent discharge, lithium metal loses electrons and converts into lithium ions, which migrate through the solid electrolyte layer to the positive electrode and then embed into the lattice of the positive electrode active material. Based on the excellent theoretical specific capacity of lithium metal (e.g., up to 3860 mAh / g), this solid-state battery has excellent energy density. Although a first carbon layer and a second carbon layer are set in this solid-state battery, due to factors such as energy, kinetics, and solid-phase interface characteristics, lithium metal deposition is more advantageous than lithium ion embedding in graphite, and lithium metal deposition still dominates at the negative electrode.

[0169] The positive electrode active layer includes positive electrode active materials. "Positive electrode active materials" refers to materials used in the positive electrode layer that have the ability to reversibly extract and insert active ions. There is no particular limitation on the active ions; however, they can be lithium ions, in which case it corresponds to a lithium-ion solid-state battery.

[0170] In this application, unless otherwise specified, "solid electrolyte material" refers to an electrolyte material or electrolyte substance that exists in solid form during the storage and fabrication of solid-state batteries and components constituting solid-state batteries, as well as during the operation of solid-state batteries. It is understood that this includes, but is not limited to, solid electrolyte materials existing in solid form at room temperature.

[0171] In a first aspect of this application, a solid-state battery is provided, comprising a negative current collector, a second carbon layer, a first carbon layer, a solid electrolyte layer, and a positive electrode layer sequentially stacked. The second carbon layer comprises a second carbon material, and the first carbon layer comprises a first carbon material. The second carbon material has a very low pore volume fraction, and the first carbon material has the ability to rapidly transport active ions (e.g., this can be achieved by controlling the ion diffusion coefficient and / or pore volume fraction of the first carbon material to be greater than that of the second carbon material). The second carbon material has a D... v At least one of the particle size and average particle size is smaller than that of the first carbon material. This solid-state battery exhibits significantly extended cycle life, as well as high battery reliability.

[0172] In some embodiments, the first carbon material is a porous carbon material. Unless otherwise specified, "porous carbon material" refers to a carbon material having a porous structure with a certain pore volume fraction.

[0173] In some embodiments, the ion diffusion coefficient and / or pore volume fraction of the first carbon material are greater than those of the second carbon material.

[0174] In some embodiments, a solid-state battery is provided, comprising a negative current collector, a second carbon layer, a first carbon layer, a solid electrolyte layer, and a positive electrode layer sequentially stacked. The second carbon layer comprises a second carbon material, and the first carbon layer comprises a first carbon material. The second carbon material has a very low pore volume fraction. The ion diffusion coefficient and / or pore volume fraction of the first carbon material is greater than that of the second carbon material. The D0 of the second carbon material is... v At least one of 50 and average particle size is smaller than that of the first carbon material. Furthermore, the first carbon material is a porous carbon material.

[0175] In some embodiments, a solid-state battery is provided, comprising a negative current collector, a second carbon layer, a first carbon layer, a solid electrolyte layer, and a positive electrode layer sequentially stacked. The second carbon layer comprises a second carbon material, and the first carbon layer comprises a first carbon material. The second carbon material has a very low pore volume fraction. The ion diffusion coefficient and / or pore volume fraction of the first carbon material is greater than that of the second carbon material. The D0 of the second carbon material is... v At least one of 50 and average particle size is smaller than that of the first carbon material. Furthermore, the first carbon material is a porous carbon material.

[0176] In some embodiments, the pore volume fraction of the second carbon material is ≤5%.

[0177] In some embodiments, a solid-state battery is provided, comprising a negative electrode current collector, a second carbon layer, a first carbon layer, a solid electrolyte layer, and a positive electrode layer sequentially stacked. The second carbon layer comprises a second carbon material, and the first carbon layer comprises a first carbon material. The first carbon material is a porous carbon material; the pore volume fraction of the second carbon material is less than or equal to 5%; at least one of the ion diffusion coefficient and the pore volume fraction of the first carbon material is greater than that of the second carbon material; the D0 of the second carbon material is... v At least one of 50 and average particle size is smaller than that of the first carbon material.

[0178] In a solid-state battery, a first carbon layer is located between a second carbon layer and a solid electrolyte layer, and a second carbon layer is located between a negative electrode current collector and a first carbon layer. The first carbon layer comprises a porous first carbon material, and the second carbon layer comprises a second carbon material without a clearly defined pore structure.

[0179] In this application, unless otherwise stated, the "second carbon material" has no obvious pore structure and has a very low pore volume fraction, for example, ≤5%.

[0180] In this application, unless otherwise stated, "first carbon material" is a porous material that can mediate the rapid transport of active ions through its surface and interface.

[0181] In some embodiments, at least one of the ion diffusion coefficient and pore volume fraction of the first carbon material is greater than that of the second carbon material.

[0182] In some embodiments, the ion diffusion coefficient of the first carbon material is greater than that of the second carbon material.

[0183] In this application, unless otherwise specified, the "ion diffusion coefficient" of carbon materials refers to the diffusion coefficient of carbon materials mediated by ion transport, and more specifically, the lithium-ion diffusion coefficient. Unless otherwise specified, the test temperature is 25°C. Units can be square centimeters per second (cm²). 2 / s) or square meters per second (m 2 / s). The ion diffusion coefficient of carbon materials can be tested using methods known in the art, such as the GITT method. The GITT technique measures the diffusion behavior of ions in the test material through a series of "pulse + constant current + relaxation" processes. More detailed steps include: first, applying a small current pulse, then turning off the current, recording the potential change, analyzing the polarization information of the electrode reaction based on this, and then calculating the diffusion coefficient.

[0184] Taking the GITT method as an example, the steps for testing the ion diffusion coefficient of the test material, using either the first carbon material or the second carbon material, are as follows:

[0185] The test temperature was 25℃. The test material was ground into a powder microelectrode. The powder microelectrode was then connected to an electrochemical workstation for coulometric titration. A pulsed current of 20 μA was used, with a titration time of 1 hour followed by a 4-hour interval (Note: To compare the effect of pulsed current and time, parallel experiments of 10 μA for 10 minutes can be performed). The GITT curve was obtained. The ion diffusion coefficient D was calculated using the following formula:

[0186] Where D is the ion diffusion coefficient; I0 ​​is the applied pulse current of 20 μA; V m dE / dx is the molar volume of the analyte, i.e., the volume of one mole of the substance; F is the Faraday constant; A is the electrode surface area; n is the charge number of the transported ion; unless otherwise specified, the transported ion is lithium ion, and n is 1; dE / dx is the slope of the coulometric titration curve, i.e., the slope of the open-circuit potential versus Li concentration curve at a certain concentration in the electrode; dE / d(t 1 / 2 ) represents the polarization voltage relative to t 1 / 2 The slope of the curve.

[0187] In some embodiments, the pore volume fraction of the first carbon material is greater than that of the second carbon material.

[0188] In some embodiments, the ion diffusion coefficient and pore volume fraction of the first carbon material are both greater than those of the second carbon material.

[0189] In this application, the "pore volume fraction" of a solid material refers to the percentage of the total pore volume in the particles relative to the particle volume. Unless otherwise specified, the pore volume fraction of a solid material can be determined using instruments and methods known in the art, referring to GB / T24586-2009, and can be tested using, but is not limited to, the gas displacement method. The testing instrument can be a Micromeritics AccuPycII 1340 true density meter. The pore volume fraction of carbon materials is calculated as (V1-V2) / V1×100%, where V1 is the apparent volume of the sample, V2 is the true volume of the sample, and nitrogen is used as the test gas.

[0190] Unless otherwise stated in this application, D v 50 refers to the particle size at which the cumulative volume distribution percentage reaches 50% in the particle size-cumulative volume distribution curve of the material. This parameter indicates that the particle size of 50% of the material's volume is less than or equal to D. v 50, and particles accounting for 50% of the material volume have a particle size greater than D. v 50. D v 90 refers to the particle size at which the cumulative volume distribution percentage reaches 90% in the particle size-cumulative volume distribution curve of the material. (D) v 10 refers to the particle size corresponding to a cumulative volume distribution percentage of 10% in the particle size-cumulative volume distribution curve of the material. Those skilled in the art will understand that D... v 50. D v 90. D v The meaning of 10 can be determined using instruments and methods known in the art. For example, it can be conveniently determined using a laser particle size analyzer, such as the MasterSizer 3000, Mastersizer 2000E, or LS-909 laser particle size analyzer from Malvern Instruments Ltd. (UK). The procedure for determining the material's D can be referenced to GB / T19077-2016 / ISO 13320:2009. v 50. D v 90. D v 10. Conduct the test.

[0191] Testing the D of the first carbon material and the second carbon material v 50. D v 90. D vThe detailed test procedure for 10 includes: taking an appropriate amount of the sample to be tested, adding deionized water as solvent (the sample concentration can be controlled to meet the 8%~12% shading level), sonicating for 5 minutes (53KHz / 120W) to fully disperse the sample, turning on the laser particle size analyzer, cleaning the optical path system, and automatically testing the background; stirring the sonicated suspension to ensure uniform dispersion, adding the uniformly dispersed sample to the injection cell, and starting the test after the sample has stabilized for 5s~10s. After the sample is poured into the injection tower, it circulates with the solution to the test optical path system. Under the irradiation of the laser beam, the particle size distribution characteristics can be obtained by receiving and measuring the energy distribution of the scattered light. Based on the test data, a particle size volume distribution map is plotted, and D is obtained from the distribution map. v 50. D v 90. D v 10. To avoid agglomeration during the drying process affecting particle size testing, a dispersion test was performed on the washed and moistened sample. Ethanol could be used as the washing reagent. The Da of the first and second carbon materials was tested. v 50. D v 90. D v 10. Suitable solvents include deionized water. Unless otherwise specified, a MasterSizer 3000 laser particle size analyzer may be used.

[0192] In this application, unless otherwise specified, the "average particle size" of the first carbon material and the second carbon material can be confirmed using the particle size statistics from scanning electron microscopy (SEM). Alternatively, a combined SEM and energy dispersive spectroscopy (EDS) scan can be used to obtain an SEM+EDS image, and the first and second carbon materials can be identified based on their elemental distribution. Based on the SEM image of the first carbon material, or based on a cross-sectional view of the first carbon layer, the particle size of each particle in the SEM image can be statistically analyzed, and the average value can be taken to obtain the "average particle size" of the first carbon material. Similarly, based on the SEM image of the second carbon material, or based on a cross-sectional view of the second carbon layer, the particle size of each particle in the SEM image can be statistically analyzed, and the average value can be taken to obtain the "average particle size" of the second carbon material. The magnification for SEM testing can range from 1000X to 30000X, such as 1000X, 2000X, 3000X, 4000X, 5000X, 6000X, 8000X, 10000X, 15000X, 20000X, 25000X, 30000X, etc., but is not limited to these; it can also be selected from any range of two of the aforementioned magnifications. The "particle size" of the selected particle refers to the largest diameter among the diameters of the particle in all directions in the SEM image. The number of particles counted must be at least 20, optionally at least 50, and further optionally at least 100.

[0193] For example, in this application, the scanning electron microscope (SEM) may be an instrument such as ZEISS Sigma 300, JEOL scanning electron microscope, or Axia ChemiSEM scanning electron microscope.

[0194] "The transverse section of the first carbon layer" refers to the cross section obtained by cutting the first carbon layer transversely.

[0195] "The transverse section of the second carbon layer" refers to the cross section obtained by cutting the second carbon layer transversely.

[0196] In this application, unless otherwise specified, "lateral" refers to the direction perpendicular to the thickness direction of the solid-state battery, and the thickness direction of the solid-state battery is referred to as "longitudinal".

[0197] In some implementations of solid-state batteries, due to factors such as energy, kinetics, and solid-phase interface characteristics, the storage of active ions at the negative electrode is mainly achieved through direct deposition on the negative electrode current collector. This solid-state battery comprises a second carbon layer, including a second carbon material, and a first carbon layer, including a first carbon material, sequentially disposed between the negative electrode current collector and the solid electrolyte layer. The first carbon material near the solid electrolyte layer is a porous carbon material with a high lithium-ion diffusion coefficient and / or a high pore volume fraction, providing abundant interfaces and a good electrolyte-first carbon layer interface. This allows the first carbon layer to quickly attract and mediate the rapid transport of active ions to the negative electrode current collector. The second carbon material near the negative electrode current collector has no obvious pore structure (corresponding to a very low pore volume fraction) and a low particle size, forming a dense and flat second carbon layer. This provides a good negative electrode current collector-second carbon layer interface, which is beneficial for inducing uniform deposition of active ions at the negative electrode current collector. Based on the aforementioned multiple effects, through multi-level interface optimization between the solid electrolyte layer-first carbon layer-second carbon layer-negative electrode current collector, the deposition behavior of active ions can be optimized, significantly suppressing local deposition and deposition inhomogeneity at the negative electrode, and significantly suppressing dendrite formation at the negative electrode. Therefore, the cycle life of the solid-state battery can be significantly extended.

[0198] It is understandable that by suppressing the formation of dendrites on the negative electrode, short circuits in the battery can also be suppressed, thereby improving the reliability of solid-state batteries.

[0199] In this application, the uniformity of lithium deposition can be observed by the following method: The battery is fully charged, and the solid-state cell is cut longitudinally to obtain a longitudinal cross-section. Scanning electron microscopy (SEM) is then performed. The stacking status and thickness of each structural layer (negative electrode current collector, second carbon layer, first carbon layer, solid electrolyte layer, and positive electrode layer) can be observed based on the SEM image. The uniformity of lithium deposition can be observed and analyzed at the interface between the negative electrode current collector and the second carbon layer. The longitudinal cross-section of the solid-state cell can be obtained using instruments or equipment including, but not limited to, focused electron beam (FIB) microscopes (non-limiting examples such as the FEI Scios 2HiVac device), ion cross-section polishers, or ion beam polishers (non-limiting examples such as the IB-09010CP argon ion cross-section polisher and IB-19500CP ion cross-section polisher from JEOL Corporation, Japan). Alternatively, plasma quenching can be used to obtain the longitudinal cross-section of the solid-state cell. SEM testing can be performed using instruments such as ZEISS Sigma 300, JEOL scanning electron microscope, and Axia Chemi SEM.

[0200] The solid-state battery provided in this application has a very uniform deposition of lithium on the negative electrode current collector, and the deposition surface is very flat (the flatness of the deposition surface can be judged by analyzing the longitudinal cross-section at different locations).

[0201] In some embodiments, the first carbon material and the second carbon material satisfy one or more of the following characteristics (any numerical parameter of the following characteristics may also be selected from any suitable value or range in the context):

[0202] (a1) The ion diffusion coefficient of the first carbon material is greater than or equal to 1×10⁻⁶ -9 cm 2 / s, optional 1×10 -9 cm 2 / s~5×10 -9 cm 2 / s;

[0203] (a2) The ion diffusion coefficient of the second carbon material is greater than or equal to 1×10⁻⁶ -10 cm 2 / s, optional 1×10 -10 cm 2 / s -1 ~1×10 -9 cm 2 / s.

[0204] In some embodiments, the first carbon material and the second carbon material satisfy one or more of the following characteristics (any numerical parameter of the following characteristics may also be selected from any suitable value or range in the context):

[0205] (a1') The ion diffusion coefficient of the first carbon material is 2 × 10⁻⁶ -9 cm 2 / s~5×10 -9 cm 2 / s;

[0206] (a2') The ion diffusion coefficient of the second carbon material is 2 × 10⁻⁶. -10 cm 2 / s~8×10 -10 cm 2 / s.

[0207] Without limitation, the ion diffusion coefficient of the first carbon material can be greater than or equal to 1 × 10⁻⁶. -9 cm 2 / s, optional 1×10 -9 cm 2 / s~5×10 -9 cm 2 / s, further optional to 2×10 -9 cm 2 / s~5×10 -9 cm 2 / s can also be any of the following values, or greater than or equal to any of the following values, or a range consisting of any two of the following values: 1×10 -9 cm 2 / s, 1.2×10 -9 cm 2 / s, 1.4×10 -9 cm 2 / s, 1.5×10 -9 cm 2 / s, 1.6×10 -9 cm 2 / s, 1.8×10 -9 cm 2 / s, 2×10 -9 cm 2 / s, 2.5×10 -9 cm 2 / s, 3×10 -9 cm 2 / s, 3.5×10 -9 cm 2 / s, 4×10 -9 cm 2 / s, 4.5×10 -9 cm 2 / s, 5×10 -9 cm 2 / s etc.

[0208] Without limitation, the ion diffusion coefficient of the second carbon material can be greater than or equal to 1 × 10⁻⁶. -10 cm 2 / s, optional 1×10 -10 cm 2 / s -1 ~1×10 -9 cm 2 / s, further optional to 2×10 -10 cm 2 / s~1×10 -9 cm 2 / s can also be any of the following values, or greater than or equal to any of the following values, or a range consisting of any two of the following values: 1×10 -10 cm 2 / s, 1.2×10 -10 cm 2 / s, 1.4×10 -10 cm 2 / s, 1.5×10 -10 cm 2 / s, 1.6×10 -10 cm 2 / s, 1.8×10 -10 cm 2 / s, 2×10 -10 cm 2 / s, 2.5×10 -10 cm 2 / s, 3×10 -10 cm 2 / s, 4×10 -10 cm 2 / s, 5×10 -10 cm 2 / s, 6×10 -10 cm 2 / s, 7×10 -10 cm 2 / s, 8×10 -10 cm 2 / s、9×10 -10 cm 2 / s, 1×10 -9 cm 2 / s etc.

[0209] By controlling the ion diffusion coefficient of the first carbon material within the aforementioned range, and / or by controlling the first carbon material to have a higher ion diffusion coefficient than the aforementioned ion diffusion coefficient of the second carbon material, the ability of the first carbon layer to rapidly conduct active ions can be improved, which is beneficial for better mediating the rapid transport of active ions to the negative electrode current collector and for better suppressing the formation of dendrites on the negative electrode.

[0210] By better suppressing dendrite formation on the negative electrode, it is beneficial to extend the cycle life of solid-state batteries.

[0211] It is understandable that by improving the ability of the first carbon layer to rapidly conduct active ions, the initial coulombic efficiency can also be improved, battery kinetics can be enhanced, and battery rate performance can be optimized.

[0212] By controlling the transport kinetics of the first carbon layer, solid-state battery cells can maintain high discharge capacity even at high current densities, thus enabling them to achieve good rate performance. Furthermore, by controlling the transport kinetics of the first carbon layer, active ions can be more easily deposited and stripped at the negative electrode, thereby reducing capacity decay during cycling and improving the cycle stability of the solid-state battery.

[0213] By increasing the ion diffusion coefficients of the first and second carbon materials, the number of active ions adsorbed in the porous carbon can be reduced, thereby allowing more active ions to be deposited on the surface of the negative electrode current collector and improving the first coulombic efficiency of the solid-state battery.

[0214] In some embodiments, the first carbon layer and the second carbon layer satisfy one or more of the following characteristics (any numerical parameter of the following characteristics may also be selected from any suitable value or range in the context):

[0215] (b1) The first carbon material includes one or more of hard carbon, soft carbon, artificial graphite and natural graphite;

[0216] (b2) The second carbon material includes one or more of carbon black, carbon nanotubes, graphene and fullerene;

[0217] (b3) The second carbon material includes a doping element, which includes one or more of silver, tin, copper, silicon, magnesium and zinc; optionally, the doping element is in the form of one or more of elemental, carbon alloy and oxide.

[0218] (b4) The second carbon material is a non-porous carbon material;

[0219] (b5) The mass percentage of the first carbon material in the first carbon layer is greater than or equal to 90%, preferably 90% to 98%, and further preferably 95% to 98%;

[0220] (b6) The mass percentage of the second carbon material in the second carbon layer is greater than or equal to 90%, preferably 90% to 98%, and further preferably 95% to 98%.

[0221] In some embodiments, the first carbon layer and the second carbon layer satisfy one or more of the following characteristics (any numerical parameter of the following characteristics may also be selected from any suitable value or range in the context):

[0222] (b1') The total mass of hard carbon, soft carbon, artificial graphite and natural graphite accounts for 80% to 100% of the mass of the first carbon material;

[0223] (b2') The total mass of carbon black, carbon nanotubes, graphene and fullerene accounts for 80% to 100% of the mass of the second carbon material;

[0224] (b5') The mass percentage of the first carbon material in the first carbon layer is 95% to 98%;

[0225] (b6') The mass percentage of the second carbon material in the second carbon layer is 95% to 98%.

[0226] In some embodiments, the first carbon material includes one or more of hard carbon, soft carbon, artificial graphite, and natural graphite. Non-limitingly, the total mass of hard carbon, soft carbon, artificial graphite, and natural graphite in the first carbon material can account for 80% to 100% of the total mass, optionally 90% to 100%, or any of the following percentages or a range selected from any two of the following percentages: 80%, 82%, 84%, 85%, 86%, 88%, 90%, 92%, 94%, 95%, 96%, 97%, 98%, 99%, 100%, etc.

[0227] By controlling the first carbon material to include the aforementioned porous carbon materials, such as one or more of hard carbon, soft carbon, artificial graphite and natural graphite, abundant interfaces can be provided, which can quickly conduct active ions. This enables the first carbon layer to quickly attract and mediate the rapid transport of active ions to the negative electrode current collector, which is beneficial to better suppress the formation of dendrites on the negative electrode.

[0228] In some embodiments, the first carbon material includes hard carbon. Non-limitingly, the mass percentage of hard carbon in the first carbon material can be 80% to 100%, optionally 90% to 100%, or any of the following percentages or a range selected from any two of the following percentages: 80%, 82%, 84%, 85%, 86%, 88%, 90%, 92%, 94%, 95%, 96%, 97%, 98%, 99%, 100%, etc.

[0229] In some embodiments, the second carbon material includes one or more of carbon black, carbon nanotubes, graphene, and fullerene. Non-limitingly, the total mass percentage of carbon black, carbon nanotubes, graphene, and fullerene in the second carbon material can be 80% to 100%, optionally 90% to 100%, or any of the following percentages or a range selected from any two of the following percentages: 80%, 82%, 84%, 85%, 86%, 88%, 90%, 92%, 94%, 95%, 96%, 97%, 98%, 99%, 100%, etc.

[0230] In some embodiments, the second carbon material is a non-porous carbon material.

[0231] In this application, unless otherwise specified, "non-porous carbon material" refers to a carbon material with a substantially non-porous structure, containing very few pores in its bulk phase, for example, a pore volume fraction of ≤5%, optionally ≤1%, or even close to 0. Non-limiting examples of non-porous carbon materials include solid particulate materials such as carbon black, carbon nanotubes, graphene, and fullerenes.

[0232] By controlling the second carbon material to include one or more of the aforementioned non-porous carbon materials, such as carbon black, carbon nanotubes, graphene, and fullerene, a dense and flat surface can be formed, which is more conducive to inducing the uniform deposition of active ions on the negative electrode current collector and is more conducive to better suppressing the formation of dendrites on the negative electrode.

[0233] In some embodiments, the second carbon material includes a dopant element. Non-limitingly, the dopant element may include one or more of silver, tin, copper, silicon, magnesium, and zinc. Non-limitingly, the dopant element may be in the form of one or more of elemental, carbon alloy, and oxide. A non-limiting example of an oxide of the dopant element is zinc oxide.

[0234] Non-limiting, the mass percentage of the first carbon material in the first carbon layer may be greater than or equal to 90%, optionally 90% to 98%, further optionally 95% to 98%, and may also be any of the following percentages or a range selected from any two of the following percentages: 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, etc.

[0235] Non-limitingly, the mass percentage of the second carbon material in the second carbon layer can be greater than or equal to 90%, optionally 90% to 98%, further optionally 95% to 98%, and can also be any of the following percentages or a range selected from any two of the following percentages: 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, etc.

[0236] The elemental composition and material type of the first and second carbon materials can be tested using methods and instruments already available in the art. Non-limitingly, methods such as Raman spectroscopy, energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma optical emission spectrometry (ICP), and Fourier transform infrared spectroscopy (FT-IR) can be used, and optionally combined with particle morphology analysis methods, such as scanning electron microscopy (SEM). The sample preparation and testing methods for these methods are known to those skilled in the art, and the test parameters can be appropriately adjusted according to the structure of the material or substance and the characteristics of the sample.

[0237] Using the distinction between natural graphite and artificial graphite as a non-limiting example, natural graphite and artificial graphite can be distinguished by the appearance and morphology of the particles; X-ray diffraction (XRD) analysis can be further performed. In the XRD pattern, if the characteristic peak near 2θ26.5° is very sharp and has a high intensity, it is natural graphite; if the characteristic peak near 2θ26.5° is relatively broad and has a weaker intensity, it is artificial graphite.

[0238] Taking the distinction between graphite and soft carbon as an example, Raman spectroscopy can be used for testing and analysis to differentiate them; more specifically, the characteristic peak information of carbon components in the spectrum (such as the intensity ratio of the D peak to the G peak, I) can be used. D / G The analysis focused on soft carbon. Both the D and G peaks are Raman characteristic peaks of carbon atom crystals. The D peak represents defects in the carbon atom crystal; the more defects, the greater the intensity of the D peak. The intensity of the D peak reflects the content of amorphous (randomly stacked) regions. The G peak represents the in-plane stretching vibrations of sp2 hybridized carbon atoms; the intensity of the G peak reflects the content of graphitized (layered structure) regions. As the degree of disorder in carbon atoms increases, the intensity ratio of the D peak to the G peak also increases. The Raman spectra can also be compared. D / G Standard Raman spectrum of graphite I D / G The differences between the two peaks can be used to determine whether the material being tested contains soft carbon. Similarly, based on the differences in information between the D and G peaks in the Raman spectrum, such as peak shape, peak position, and intensity, graphite and hard carbon can be distinguished, as well as natural graphite and artificial graphite.

[0239] Similarly, based on the differences in information between the D and G peaks in the Raman spectrum, such as peak shape, peak position, and intensity, the types of second carbon materials can also be distinguished.

[0240] In some embodiments, the first carbon material includes a porous structure, and the first carbon material satisfies one or more of the following characteristics (any numerical parameter of the following characteristics may also be selected from any suitable value or range in the context):

[0241] (c1) The pore volume fraction of the first carbon material is greater than or equal to 25%, optionally 30% to 60%, and further optionally 35% to 55%;

[0242] (c2) The pore volume of the first carbon material is greater than or equal to 0.1 cm³. 3 / g, can be selected as 0.1cm 3 / g~0.5cm 3 / g; where, the pore volume of the material refers to the ratio of the total pore volume in the particles to the mass of the particles;

[0243] (c3) The pore structure in the first carbon material includes mesopores and micropores, wherein the diameter of mesopores is 2m to 50nm and the diameter of micropores is less than 2nm.

[0244] In some embodiments, the pore volume fraction of the first carbon material is greater than or equal to 25%, optionally 30% to 60%, further optionally 35% to 55%, and may also be any of the following percentages, or greater than or equal to any of the following percentages, or selected from any two of the following percentages: 30%, 35%, 40%, 45%, 50%, 55%, 60%, etc.

[0245] The "pore volume fraction" and "pore volume" of a material can reflect the richness of its pore structure.

[0246] In this application, unless otherwise specified, the "pore volume" of a material refers to the ratio of the total pore volume in the particles to the particle mass. It can be obtained using a similar method to that used for testing pore volume fraction. The pore volume of a carbon material is calculated as (V1 - V2) / M. C V1 is the apparent volume of the sample, V2 is the actual volume of the sample, and M... C Nitrogen gas was used as the test gas to measure the mass of the carbon material to be tested.

[0247] In some embodiments, the pore volume of the first carbon material is greater than or equal to 0.1 cm³. 3 / g, can be selected as 0.1cm 3 / g~0.5cm 3 / g can also be any of the following values, or greater than or equal to any of the following values, or a range selected from any two of the following values: 0.1cm 3 / g, 0.15cm 3 / g, 0.2cm 3 / g, 0.25cm 3 / g, 0.3cm 3 / g, 0.35cm 3 / g, 0.4cm 3 / g, 0.45cm 3 / g, 0.5cm 3 / g etc.

[0248] By controlling one or two parameters of the pore volume fraction and pore volume of the first carbon material within the aforementioned range, it is beneficial to provide a richer interface for the first carbon layer, to enhance the ability of the first carbon layer to rapidly conduct active ions, to promote the rapid attraction and mediation of active ions to the negative electrode current collector by the first carbon layer, and to suppress the formation of dendrites on the negative electrode; in addition, the structural strength of the first carbon material can also be taken into account.

[0249] By controlling the pore volume fraction and / or pore volume of the first carbon material within the aforementioned range, on the one hand, a higher total amount of micropores and mesopores can be achieved, with fewer macropores, providing a rich pore structure that facilitates the rapid transport of active ions to the surface of the negative electrode current collector; on the other hand, the first carbon material can also have good structural strength, which can better withstand the volume changes caused by the deposition of active metals and better suppress the volume expansion of the negative electrode.

[0250] In some embodiments, the pore structure in the first carbon material includes mesopores and micropores. Unless otherwise specified, the diameter of mesopores is 2 nm to 50 nm, and the diameter of micropores is less than 2 nm. In this case, mesopores and micropores can increase the specific surface area of ​​the first carbon material, which is beneficial for increasing the adsorption sites of active ions, providing better channels for the diffusion of active ions within the first carbon material, and further improving the active ion transport rate of the first carbon material.

[0251] In some embodiments, the first carbon material satisfies one or more of the following characteristics (any numerical parameter of the following characteristics may also be selected from any suitable value or range in the context):

[0252] (d1) The proportion of mesopores in the pore structure is 5% to 50%, optionally 10% to 40%, and further optionally 10% to 20%.

[0253] (d2) The proportion of micropores in the pore structure is 10% to 80%, and can be selected as 10% to 65%.

[0254] In some embodiments, the first carbon material satisfies one or more of the following characteristics (any numerical parameter of the following characteristics may also be selected from any suitable value or range in the context):

[0255] (d1') Mesopores account for 10% to 40% of the total number of pore structures;

[0256] (d2') Micropores account for 10% to 65% of the total number of pores in the pore structure.

[0257] Non-limitingly, the proportion of mesopores in the pore structure can be 5% to 50%, optionally 10% to 40%, further optionally 10% to 20%, and can also be any of the following percentages or a range selected from any two of the following percentages: 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, etc.

[0258] Non-limitingly, the proportion of micropores in the pore structure can be 10% to 80%, optionally 10% to 65%, or any of the following percentages or a range selected from any two of the following percentages: 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, etc.

[0259] By controlling the proportion of mesopores and / or micropores in the pore structure within the aforementioned range, it is beneficial to provide a richer surface interface for the first carbon layer, to enhance the ability of the first carbon layer to rapidly conduct active ions, to promote the rapid attraction and mediation of active ions to the negative electrode current collector by the first carbon layer, and to suppress the formation of dendrites on the negative electrode.

[0260] The proportion of mesopores and micropores in the pore structure can be tested using methods already available in the art, including but not limited to gas adsorption methods such as nitrogen adsorption. At liquid nitrogen temperature, nitrogen is adsorbed on the surface of porous materials, and adsorption isotherms are plotted by measuring the amount of nitrogen adsorbed under different relative pressures. For microporous materials, the volume and proportion of micropores can be determined using methods such as the t-plot method, αs-plot method, or Dubining's micropore filling theory. For mesoporous materials, the volume and proportion of mesopores can be calculated from the adsorption isotherms using methods such as the Barrett-Joyner-Halenda method (BJH), thus determining the proportion of mesopores to micropores. Refer to GB / T 21650.2-2008. Instruments that can be used, but are not limited to, include: fully automated specific surface area and pore size distribution analyzers, gas adsorption analyzers, etc.

[0261] For example, the sizes of mesopores and micropores in the first carbon material can be measured using morphology images obtained by methods such as high-resolution scanning electron microscopy (SEM), and then the proportion of mesopores and micropores in the pore structure can be obtained based on the statistical results. The scanning electron microscope (SEM) used for observing and measuring mesopores and micropores can be an instrument such as a ZEISS Sigma 300, JEOL scanning electron microscope, or Axia ChemiSEM. The number of pores counted to obtain the proportion of mesopores and / or micropores in the pore structure should be at least 20, and more preferably at least 50. The statistical range includes micropores with a diameter less than 2 nm, mesopores with a diameter of 2 nm to 50 nm, and macropores with a diameter greater than 50 nm. For the "diameter" of micropores, mesopores, and macropores, if the pore structure is a three-dimensional pore such as a sphere, ellipsoid, or irregular shape, the "diameter" of the pore structure refers to the maximum diameter of the corresponding pore structure in all directions of the morphology diagram; if the pore structure is a shape with a certain length-to-diameter ratio such as a channel, the "diameter" of the pore structure refers to the maximum diameter of the corresponding channel at different length positions.

[0262] In some embodiments, the first carbon material satisfies one or more of the following characteristics (any numerical parameter of the following characteristics may also be selected from any suitable value or range in the context):

[0263] (e1) D of the first carbon material v 50 is 50nm to 2μm, can be selected as 500nm to 2μm, and can be further selected as 500nm to 1.5μm;

[0264] (e2) The first carbon material satisfies SPAN1 of 1.5 to 4, and can be selected as 1.5 to 2;

[0265] (e3) The specific surface area of ​​the first carbon material is 50m². 2 / g~500m 2 / g, optional 300m 2 / g~500m 2 / g;

[0266] (e4) The compaction density of the first carbon material powder under 5 tons of pressure is 0.75 g / cm³. 3 ~0.9g / cm 3 .

[0267] In some embodiments, the first carbon material D v50 can be 50nm to 2μm, optionally 500nm to 2μm, further optionally 500nm to 1.5μm, or any of the following values, or a range consisting of any two of the following values: 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, 600nm, 700nm, 800nm, 900nm, 1000nm or 1μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm, 1.5μm, 1.6μm, 1.7μm, 1.8μm, 1.9μm, 2μm, etc.

[0268] In this application, the first carbon material D v 50 is denoted as D v 501, the first carbon material D v 90 is written as D v 901, the first carbon material D v 10 is denoted as D v 101, the SPAN value of the first carbon material is denoted as SPAN1, SPAN1 = (D v 901-D v 101) / D v 501. The larger the SPAN value, the wider the particle size distribution; conversely, the smaller the SPAN value, the narrower the particle size distribution and the better the particle size uniformity.

[0269] In some embodiments, the first carbon material satisfies SPAN1 as 1.5 to 4, which can be selected as 1.5 to 2, or any of the following values, or a range consisting of any two of the following values: 1.5, 1.6, 1.8, 2, 2.2, 2.4, 2.5, 2.6, 2.8, 3, 3.2, 3.4, 3.5, 3.6, 3.8, 4, etc.

[0270] In some embodiments, the specific surface area of ​​the first carbon material is 50 m². 2 / g~500m 2 / g, optional 300m 2 / g~500m 2 / g can also be any of the following values, or a range selected from any two of the following values: 50m 2 / g、55m 2 / g、60m 2 / g、65m 2 / g、70m 2 / g、80m 2 / g、90m 2 / g, 100m 2 / g, 150m2 / g、200m 2 / g、250m 2 / g、300m 2 / g, 350m 2 / g、400m 2 / g、450m 2 / g、500m 2 / g etc.

[0271] In this application, unless otherwise specified, the term "specific surface area" has the meaning known in the art. It can be measured using nitrogen adsorption specific surface area analysis and calculated using the BET (Brunauer Emmett Teller) method. Nitrogen adsorption specific surface area analysis can be performed using a Tri Star II 3020 specific surface area and porosity analyzer from Micromeritics, Inc.

[0272] The specific surface area of ​​the material can be determined according to GB / T19587-2017, using the nitrogen adsorption specific surface area analysis method, and calculated using the BET (Brunauer Emmett Teller) method. The testing instrument can be the Tri-Star 3020 specific surface area and pore size analyzer from 5Micromeritics, USA.

[0273] By controlling the specific surface area of ​​the first carbon material within the aforementioned range, the larger specific surface area of ​​porous carbon can promote the rapid transport of lithium ions to the surface of the negative electrode current collector, improve the ion transport kinetics of the negative electrode, and reduce the adsorption of lithium ions in the porous carbon.

[0274] In some embodiments, the compaction density of the first carbon material powder under a pressure of 5 tons is 0.75 g / cm³. 3 ~0.9g / cm 3 It can also be any of the following values, or a range selected from any two of the following values: 0.75 g / cm³ 3 0.76 g / cm 3 0.78g / cm 3 0.80g / cm 3 0.72g / cm 3 0.84 g / cm 3 0.85g / cm 3 0.76 g / cm 3 0.88g / cm 3 0.9g / cm 3 wait.

[0275] In this application, unless otherwise specified, the term "powder compaction density" has a commonly known meaning in the art, referring to the ratio of the mass to the volume of a powder material after compaction under a certain pressure. The "powder compaction density" of a powder material can be determined using instruments and methods known in the art. For example, it can be determined using an electronic pressure testing machine (e.g., UTM7305) in accordance with standard GB / T24533-2009. Unless otherwise specified, the test method is as follows: Weigh a mass M0 of the powder material to be tested, add it to a mold with a bottom area of ​​A0, pressurize it to a certain pressure P0, maintain the pressure for a certain time (e.g., 5T for 30s), then release the pressure, maintain the pressure for a period of time (e.g., 10s), and then record and calculate the powder compaction density of the material under pressure P0. Unless otherwise specified, the pressure P0 for testing the powder compaction density is 5T.

[0276] The following method can be used for testing: Weigh 201.0000±0.0500g of sample and place it in a test mold with a diameter of 13mm (e.g., CARVER#3619). Then, place the powder sample in the testing equipment. Select the following test conditions: 5 tons pressure, pressure increase rate 10mm / min, pressure increase holding time 30s, pressure release rate 30mm / min, and pressure release holding time 10s. Measure the compacted density of the sample when the pressure is released. The powder compacted density of the sample = sample mass / (mold area × sample thickness). The testing equipment can be a UTM7305 compaction density tester.

[0277] The "powder compaction density under 5 tons of pressure" for the first or second carbon material refers to the powder compaction density measured under 5 tons (5T) of pressure. This pressure condition is better matched to the particle packing conditions of the first and second carbon layers.

[0278] By controlling the D of the first carbon material v 50. One or more of the parameters among SPAN1, specific surface area and powder compaction density under 5 tons of pressure, within the aforementioned range, can adjust the packing density of the first carbon material, which is beneficial to make the first carbon layer have a more suitable porosity, more suitable for rapid conduction of active ions, more conducive to the first carbon layer to rapidly attract and mediate the rapid transport of active ions to the negative electrode current collector, and more conducive to suppressing the formation of dendrites on the negative electrode.

[0279] In some embodiments, the second carbon material satisfies one or more of the following characteristics (any numerical parameter of the following characteristics may also be selected from any suitable value or range in the context):

[0280] (f1) The average diameter of the primary particles in the second carbon material is 20 nm to 100 nm, which can be selected as 20 nm to 80 nm, and further selected as 20 nm to 50 nm;

[0281] (f2) The specific surface area of ​​the second carbon material is 25m². 2 / g~50m 2 / g, optional 40m 2 / g~50m 2 / g;

[0282] (f3) The compaction density of the second carbon material powder under a pressure of 5 tons is 0.7 g / cm³. 3 ~0.9g / cm 3 ;

[0283] (f4) The pore volume fraction of the second carbon material is less than 5%, which can be selected as 0 to 1%, and further can be less than 1%.

[0284] In some embodiments, the average diameter of the primary particles in the second carbon material is 20 nm to 100 nm, optionally 20 nm to 80 nm, or any of the following values ​​or a range selected from any two of the following values: 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, etc.

[0285] In this application, "primary particle" in the second carbon material refers to the basic particle unit in the second carbon material.

[0286] In this application, the "average diameter of primary particles" in the second carbon material can be confirmed using statistical results of particle diameter from scanning electron microscopy (SEM). Alternatively, a combined SEM and EDS scan can be used to obtain an SEM+EDS image, and the primary particles in the second carbon material can be identified based on elemental distribution. Based on the SEM image of the second carbon material, or based on a cross-sectional view of the second carbon layer, the particle size of each primary particle in the second carbon material in the SEM image can be statistically analyzed, and the average value can be taken to obtain the "average diameter of primary particles" in the second carbon material. The diameter of the selected primary particle refers to the maximum diameter among the anisotropic diameters of that primary particle in the SEM image. The number of primary particles counted is at least 20, and possibly at least 50, or at least 100.

[0287] In some embodiments, the specific surface area of ​​the second carbon material is 25 m². 2 / g~50m 2 / g, optional 30m 2 / g~50m 2 / g, optional 40m 2 / g~50m 2 / g can also be any of the following values, or a range selected from any two of the following values: 25m 2 / g、26m 2 / g、28m 2 / g、30m 2 / g、32m2 / g、34m 2 / g、35m 2 / g、36m 2 / g、38m 2 / g、40m 2 / g、42m 2 / g、44m 2 / g、45m 2 / g、46m 2 / g、48m 2 / g、49m 2 / g, 50m 2 / g etc.

[0288] By controlling one or more of the following parameters within the aforementioned range: the average diameter of the primary particles in the second carbon material, the specific surface area of ​​the second carbon material, and the compaction density of the powder under 5 tons of pressure in the second carbon material, the packing density of the second carbon material can be adjusted. This is beneficial for making the second carbon layer denser and smoother, for inducing more uniform deposition of active ions on the negative electrode current collector, and for suppressing dendrite formation on the negative electrode.

[0289] In some embodiments, the specific surface area of ​​the second carbon material is smaller than that of the first carbon material. In this case, the specific surface area of ​​the smaller-sized second carbon material is smaller than that of the porous, larger-sized first carbon material.

[0290] In some embodiments, the pore volume fraction of the second carbon material is ≤5%, which can be 0-5%, optionally 0-2%, and further optionally 0-1%. Non-limitingly, the pore volume fraction of the second carbon material can be any of the following percentages, or less than or equal to any of the following pore volume fractions, or less than any of the following pore volume fractions, or greater than or equal to 0 and less than or equal to any of the following pore volume fractions, or greater than or equal to 0 and less than any of the following pore volume fractions, or selected from the range of any two of the following pore volume fractions: 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.8%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc.

[0291] By controlling the pore volume fraction of the second carbon material within a low range, it is beneficial to make the second carbon layer denser and smoother.

[0292] In some implementations, solid-state batteries satisfy one or more of the following characteristics (any numerical parameter of the following characteristics may also be selected from any suitable value or range in the context):

[0293] (g1) The thickness of the first carbon layer is 2μm to 8μm, and can be selected as 2.5μm to 7.5μm;

[0294] (g2) The thickness of the second carbon layer is 2μm to 8μm, and can be selected as 2.5μm to 7.5μm;

[0295] (g3) The thickness ratio of the first carbon layer to the second carbon layer is 5:1 to 1:5, and can be selected as 3:1 to 1:3.

[0296] In some implementations, solid-state batteries satisfy one or more of the following characteristics (any numerical parameter of the following characteristics may also be selected from any suitable value or range in the context):

[0297] (g1') The thickness of the first carbon layer is 2.5 μm to 7.5 μm;

[0298] The thickness of the second carbon layer (g2') is 2.5 μm to 7.5 μm;

[0299] (g3') The thickness ratio of the first carbon layer to the second carbon layer is 3:1 to 1:3;

[0300] (g4') The sum of the thicknesses of the first and second carbon layers is 5 μm to 15 μm.

[0301] Non-limitingly, the thickness of the first carbon layer can be 2 μm to 8 μm, or any of the following values ​​or a range selected from any two of the following values: 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, etc.

[0302] By controlling the thickness of the first carbon layer within the aforementioned range, it is beneficial to better leverage the role of the first carbon layer in rapidly attracting and mediating the rapid transport of active ions, and to better suppress the formation of dendrites on the negative electrode.

[0303] Non-limitingly, the thickness of the second carbon layer can be 2 μm to 8 μm, and can also be any of the following values ​​or a range selected from any two of the following values: 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, etc.

[0304] By controlling the thickness of the second carbon layer within the aforementioned range, it is beneficial to better leverage the role of the second carbon layer in inducing the uniform deposition of active ions on the negative electrode current collector, and to better suppress the formation of dendrites on the negative electrode.

[0305] Non-limitingly, the thickness ratio of the first carbon layer to the second carbon layer can be from 5:1 to 1:5, optionally from 3:1 to 1:3, or any of the following ratios or a range selected from any two of the following ratios: 5:1, 4.5:1, 4:1, 3.5:1, 3:1, 2.5:1, 2:1, 1.5:1, 1:1, 1:1.5, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, etc.

[0306] By controlling the thickness ratio of the first carbon layer to the second carbon layer within the aforementioned range, it is beneficial to enable the first carbon layer and the second carbon layer to work together better, to better balance the rapid transport of active ions to the negative electrode current collector and the uniform deposition on the negative electrode current collector, and to better suppress the formation of dendrites on the negative electrode.

[0307] Non-limitingly, the sum of the thicknesses of the first carbon layer and the second carbon layer can be 5 μm to 15 μm, or any of the following values ​​or a range selected from any two of the following values: 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm, 10 μm, 11 μm, 12 μm, 12.5 μm, 13 μm, 13.5 μm, 4 μm, 14.5 μm, 15 μm, etc.

[0308] By controlling the sum of the thicknesses of the first carbon layer and the second carbon layer within the aforementioned range, the active ion transport distance between the solid electrolyte layer and the negative electrode current collector can be controlled within a more suitable range, which is beneficial to better improve the initial coulombic efficiency, battery kinetics, and battery rate performance.

[0309] In some implementations, solid-state batteries satisfy one or more of the following characteristics (any numerical parameter of the following characteristics may also be selected from any suitable value or range in the context):

[0310] (h1) The first carbon layer includes a first adhesive;

[0311] (h2) The second carbon layer includes a second binder.

[0312] In this application, the binder in the first carbon layer is referred to as "first binder", the binder in the second carbon layer is referred to as "second binder", and the binder in the solid electrolyte layer is referred to as "third binder".

[0313] In this application, the terms "first," "second," and "third" in "first adhesive," "second adhesive," and "third adhesive" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features.

[0314] By setting a binder (denoted as the first binder) in the first carbon layer, it is beneficial to improve the electrical contact network between the first carbon materials, to better exert the role of the first carbon layer in mediating the rapid transport of active ions, and to better suppress the formation of dendrites on the negative electrode.

[0315] By setting a binder (denoted as the second binder) in the second carbon layer, it is beneficial to make the second carbon layer denser and smoother, which is beneficial to induce active ions to deposit more uniformly on the negative electrode current collector and to suppress dendrite formation on the negative electrode.

[0316] In some implementations, solid-state batteries satisfy one or more of the following characteristics (any numerical parameter of the following characteristics may also be selected from any suitable value or range in the context):

[0317] (h1') The first carbon layer includes a first adhesive, which includes one or more of polyvinylidene fluoride (PVDF), polyacrylic acid (PAA), styrene-butadiene rubber (SBR), and carboxymethyl cellulose (CMC);

[0318] (h2') The second carbon layer includes a second adhesive, which includes one or more of polyvinylidene fluoride, polyacrylic acid, styrene-butadiene rubber and carboxymethyl cellulose;

[0319] (h3') The mass percentage of the first binder in the first carbon layer is 2% to 10%, and can be selected as 2% to 5%;

[0320] (h4') The second binder has a mass percentage of 2% to 10% in the second carbon layer, and can be selected as 2% to 5%.

[0321] In some embodiments, the first carbon layer includes a first binder. Non-limitingly, the first binder may include one or more of polyvinylidene fluoride, polyacrylic acid, styrene-butadiene rubber, and carboxymethyl cellulose. Non-limitingly, the first binder may constitute 2% to 10% by mass in the first carbon layer, and may also be any one of the following percentages or a range selected from any two of the following percentages: 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 6%, 7%, 8%, 9%, 10%, etc.

[0322] By controlling the mass percentage of the first binder in the first carbon layer within the aforementioned range, it is beneficial to better balance the effect of the rapidly active ions of the first carbon material and the bonding effect of the first binder.

[0323] In some embodiments, the second carbon layer includes a second binder. Non-limitingly, the second binder may include one or more of polyvinylidene fluoride, polyacrylic acid, styrene-butadiene rubber, and carboxymethyl cellulose. Non-limitingly, the second binder may constitute 2% to 10% by mass in the second carbon layer, and may also be any of the following percentages or a range selected from any two of the following percentages: 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 6%, 7%, 8%, 9%, 10%, etc.

[0324] By controlling the mass percentage of the second binder in the second carbon layer within the aforementioned range, it is beneficial to better balance the density and smoothness of the second carbon layer and the electrical conductivity of the second carbon material.

[0325] Non-limiting, the binder components in solid-state batteries can be identified using one or more of the following methods: Fourier transform infrared (FT-IR) spectroscopy, ultraviolet spectroscopy, and proton nuclear magnetic resonance (NMR) spectroscopy. 1 Methods include ¹H NMR, gel permeation chromatography (GPC), high-performance liquid chromatography (HPLC), mass spectrometry, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The sample preparation and testing methods for these methods are known to those skilled in the art, and the test parameters can be appropriately adjusted according to the sample characteristics. The following method can be used for testing: disassemble the solid-state battery cell, scrape off the powder of the selected film layer, soak it in an organic solvent to fully dissolve the binder component, centrifuge, collect the liquid phase, and obtain a solution containing the binder component. This solution can be prepared as a liquid sample or dried to prepare a solid sample for detection. The organic solvent can be N-methylpyrrolidone.

[0326] In some embodiments, the negative current collector includes one or more of copper, stainless steel, nickel, titanium, aluminum, and alloys composed of at least two of copper, stainless steel, nickel, titanium, and aluminum.

[0327] The type of negative electrode current collector can be flexibly selected.

[0328] In some implementations, the solid-state battery is a negative electrode-free solid-state battery.

[0329] In electrodeless solid-state batteries, the capacity of the negative electrode is mainly contributed by the deposited lithium metal.

[0330] In some embodiments of the electrodeless solid-state battery, the sum of the thicknesses of the first carbon layer and the second carbon layer is ≤15μm, and can be ≤10μm.

[0331] In some embodiments, the solid electrolyte layer comprises a solid electrolyte material and a third binder. This facilitates the formation of large-size solid electrolyte films, enabling the fabrication of large-size batteries.

[0332] In some implementations, solid-state batteries satisfy one or both of the following characteristics:

[0333] (i1) The mass percentage of the third binder in the solid electrolyte layer is denoted as f. E Satisfying 0 <f E ≤5%, optionally, f E It ranges from 0.5% to 2%;

[0334] (i2) The third adhesive includes polytetrafluoroethylene, which accounts for 80% to 100% of the mass of the third adhesive.

[0335] Non-limiting, the mass percentage of the third binder in the solid electrolyte layer (f E ) can be 0-5%, optionally, 0 <f E ≤5%, further optionally, f E It is 0.5% to 2%. Without limitation, f E It can also be any of the following percentages or a range composed of any two of the following percentages: 0%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.8%, 1%, 1.2%, 1.5%, 1.6%, 1.8%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc.

[0336] By controlling the mass percentage (f) of the third binder in the solid electrolyte layer E Within the aforementioned range, it is beneficial to better utilize the ability of the solid electrolyte layer to rapidly conduct active ions.

[0337] In some embodiments, the third adhesive comprises polytetrafluoroethylene (PTFE). Non-limitingly, the mass percentage of PTFE in the third adhesive can be 80% to 100%, optionally 90% to 100%, or any of the following percentages or a range selected from any two of the following percentages: 80%, 82%, 84%, 85%, 86%, 88%, 90%, 92%, 94%, 95%, 96%, 97%, 98%, 99%, 100%, etc.

[0338] By controlling the third binder, including polytetrafluoroethylene (PTFE), it is beneficial to improve the chemical compatibility between the solid electrolyte material and the binder components in the solid electrolyte layer, which is more conducive to the chemical stability of the solid electrolyte layer and the efficiency and stability of its ability to conduct active ions.

[0339] In addition, PTFE can be rapidly fiberized under shear force. Fiberized PTFE can provide more bonding force between solid electrolyte particles, giving the solid electrolyte layer extremely high mechanical strength and making it less prone to cracking during densification. This can improve the processability of the solid electrolyte layer and solid-state battery.

[0340] In some embodiments, the positive electrode layer includes a positive electrode active layer, which includes one or more of lithium transition metal oxide positive electrode materials and lithium phosphate positive electrode materials.

[0341] The type of positive electrode active material in the positive electrode active layer can be flexibly selected according to the battery performance requirements.

[0342] The elemental composition of the positive electrode active material in the positive electrode active layer can be analyzed using methods known in the art, including but not limited to: inductively coupled plasma atomic emission spectrometry (ICP), X-ray diffraction (XRD), single-crystal X-ray diffraction (SCXRD), and energy dispersive spectroscopy (EDS). The sample preparation and testing methods for these methods are known to those skilled in the art, and the test parameters can be appropriately adjusted according to the sample characteristics. ICP can be used for quantitative analysis of the component content in the positive electrode active material. Alternatively, a solid-state battery can be fully discharged, then the cell can be disassembled, and the material extracted from the positive electrode active layer can be subjected to elemental analysis.

[0343] In some implementations, solid-state batteries satisfy one or both of the following characteristics:

[0344] (j1) The solid-state battery is a lithium-ion solid-state battery;

[0345] (j2) The solid-state battery is an all-solid-state battery.

[0346] In some implementations, the solid-state battery is a lithium-ion solid-state battery.

[0347] In some implementations, the solid-state battery is an all-solid-state battery.

[0348] In some of these embodiments, the solid-state battery is an all-solid-state lithium-ion secondary battery, which simultaneously satisfies features (j1) and (j2).

[0349] In this application, unless otherwise specified, "all-solid-state battery" refers to a solid-state battery in which all electrolytes are solid electrolytes. In this case, the positive electrode layer, solid electrolyte layer, first carbon layer, second carbon layer and negative electrode current collector are all made of solid materials, and no liquid electrolyte is provided in the battery, so it can be called "all-solid-state battery".

[0350] A solid-state battery includes at least one solid-state battery cell. A solid-state battery may include one or more solid-state battery cells.

[0351] In this application, unless otherwise specified, "solid-state battery cell" refers to a basic unit capable of converting chemical energy into electrical energy, and all its components are solid-state. In some embodiments, a solid-state battery cell may be an all-solid-state battery cell.

[0352] In this application, unless otherwise specified, "all-solid-state battery cell" refers to a solid-state battery cell in which all electrolytes are solid electrolytes. In this case, no liquid electrolyte is provided in the battery cell, and therefore it can be called an "all-solid-state battery cell".

[0353] In some embodiments, a solid-state battery cell includes a positive electrode layer, a solid electrolyte layer, a first carbon layer, a second carbon layer, and a negative electrode current collector. In some embodiments, the solid-state battery cell is an all-solid-state battery cell.

[0354] In some embodiments, the solid-state battery cell 5 includes a solid-state cell 52.

[0355] In some implementations, the solid-state cell is an all-solid-state cell.

[0356] In some embodiments, the solid-state battery cell 52 includes a positive electrode layer, a solid electrolyte layer, a first carbon layer, a second carbon layer, and a negative electrode current collector, which are stacked sequentially. In some embodiments, the solid-state battery cell is an all-solid-state battery cell.

[0357] The following is a description of the solid electrolyte layer.

[0358] The solid electrolyte layer acts as a conductor of ions between the positive electrode layer and the negative electrode current collector, and also isolates the positive electrode layer from the negative electrode current collector, thus preventing short circuits between the positive and negative electrodes. It is understood that the solid electrolyte layer includes a solid electrolyte material. The solid electrolyte material in the solid electrolyte layer can be any solid electrolyte material known in the art that can be used in solid-state batteries.

[0359] Non-limitingly, the mass percentage of the solid electrolyte material in the solid electrolyte layer can be 95% to 100%, optionally greater than or equal to 95% and less than 100%, further optionally 98% to 99.5%, or any of the following percentages, or greater than or equal to any of the following percentages and less than or equal to 100%, or greater than or equal to any of the following percentages and less than 100%, or selected from the range of any two of the following percentages: 95%, 95.5%, 96%, 96.5%, 97%, 97.5%, 98%, 98.5%, 99%, 99.5%, 99.9%, etc.

[0360] The solid electrolyte material in the solid electrolyte layer may include, but is not limited to, one or more of the following: sulfide solid electrolytes, halide solid electrolytes, and oxide solid electrolytes.

[0361] In some embodiments, the solid electrolyte material includes sulfide-based solid electrolytes. Among the many solid electrolyte materials currently available, sulfide electrolytes possess extremely high ionic conductivity (e.g., ≥1 mS / cm at room temperature) and excellent mechanical properties, making them one of the most promising solid electrolyte materials for solid-state battery systems.

[0362] Non-limitingly, sulfide solid electrolytes may include one or more of binary sulfide solid systems and ternary sulfide solid systems. Non-limitingly, binary sulfide solid systems may include Li₂S-P₂S₅ (such as Li₇P₃S₅). 11 The ternary sulfide solid-state system may include one or more of Li₂S-SiS₂, Li₂S-GeS₂, and Li₂S-B₂S₃. Non-limitingly, the ternary sulfide solid-state system may include Argyrodite-type sulfide electrolytes, Li₂S-M… 5 S2-P2S5 ternary sulfide electrolyte, lithium germanium phosphorus sulfide electrolyte, Li2S-P2S5-M 6 S-ternary sulfide electrolyte, Li2S-P2S5-M 6 Cl is one or more of a ternary sulfide electrolyte and a thio-LISICON type sulfide electrolyte; wherein, M 5 It may include one or more elements selected from silicon (Si), germanium (Ge), tin (Sn), and aluminum (Al); M 6 It may include one or more elements selected from Ge, Al, Sn, lead (Pb), antimony (Sb), Si, and arsenic (As).

[0363] In some embodiments, the sulfide solid electrolyte includes one or more of the following: silver sulfide-germanium sulfide electrolyte, LGPS-type sulfide electrolyte, and lithium sulfide-phosphorus pentasulfide complex-type sulfide electrolyte.

[0364] Unless otherwise specified, the sulfide electrolyte exhibits a sulfide-germanium sulfide crystal structure. Without limitation, the sulfide electrolyte may include electrolytes with the chemical formula Li 6±s P 1-j A 1 j S 5±s-t B 1 t X 1 1±s Sulfide electrolytes, where 0≤j<1, 0≤t<1, 0≤s<1, A 1It can be selected from, but is not limited to, one or more elements from Ge, Si, Sn, and Sb, B 1 X can be one or more elements from O, Se, and Te. 1 For halogens, further, X 1 It can be selected from one or more elements chosen from Cl, Br, I, and F. Non-limiting examples of sulfide electrolytes of the sulfide type include Li6PS5Cl, Li... 5.5 PS 5.5 Cl 1.5 Li 5.7 PS5Cl 1.3 wait.

[0365] Unless otherwise specified, LGPS-type sulfide electrolytes possess an LGPS-type crystalline phase structure. Non-limitingly, LGPS-type sulfide electrolytes may include those with the chemical formula Li. 10±δ5 Ge 1-g G 2 g P 2-q Q 2 q S 12-w W 2 w Sulfide electrolytes, where 0≤δ5<1, 0≤g≤1, 0≤q≤2, 0≤w<1, G 2 Q is selected from one or both elements of Si and Sn. 2 For Sb, W 2 Selected from one or more elements from O, Se, Te, Cl, Br, I, and F. Non-limiting examples of LGPS-type sulfide electrolytes include Li. 10 GeP2S 12 .

[0366] Non-limitingly, lithium pentaphosphine sulfide complex-type sulfide electrolytes may include those with the chemical formula (100-uv)Li₂S·uP₂S₅·vM 3 m N 3 n Sulfide electrolytes, of which 0 <u<100,0≤v<100,0≤u+v<100,0≤m<4,0≤n<6,M 3 It can be selected from, but is not limited to, one or more elements from Li, B, Ge, Si, Sn, and Sb, N 3 It can be selected from one or more elements from S, Se, Te, O, Cl, Br, I, and F.

[0367] Non-limiting examples of oxide solid electrolytes may include LISICON-type oxide electrolytes (such as γ-Li3PO4, etc.) and NASICON-type oxide electrolytes (such as Li...). 1+δ2 Al δ2 Ge 2-δ2 (PO4)3,Li 1+δ2 Al δ2 Ti 2-δ2 (PO4)3, etc., 0≤δ2≤1), Garnet type (such as Li7La3Zr2O) 12 (etc.), perovskite-type oxide electrolytes (such as Li, etc.) 3·δ3 La 2 / 3-δ3 One or more of the following: TiO3, 0≤δ3≤0.5, etc.

[0368] Non-limiting examples of halide solid electrolytes may include one or more of Li3InCl6, Li3YCl6, Li3ScCl6, Li3ErCl6, Li2ZrCl6, etc.

[0369] A solid electrolyte layer can be introduced through a solid electrolyte membrane.

[0370] Solid electrolyte membranes can be prepared using a dry process. In some embodiments, the solid electrolyte layer can be formed by pressing an electrolyte layer raw material comprising a solid electrolyte material into a solid electrolyte membrane. Optionally, the electrolyte layer raw material may include a binder (referred to as a third binder). The types of third binders are described in the context of this application. The pressure during dry pressing can be controlled to be lower than the pressure used for high-temperature densification during the fabrication of solid-state batteries.

[0371] Solid electrolyte membranes can also be prepared by a wet process, wherein the electrolyte slurry used includes at least a solid electrolyte material and an organic solvent, and optionally, a third binder.

[0372] In some embodiments, the solid electrolyte material in the solid electrolyte layer includes a sulfide-based solid electrolyte, and the third binder includes polytetrafluoroethylene.

[0373] This application relates to slurries including sulfide-based solid electrolytes, such as electrolyte slurries or positive electrode slurries, and the organic solvents used may include one or more of p-xylene, trimethylbenzene, butyl butyrate, heptane, etc., and may further be pseudotrimethylbenzene or p-xylene.

[0374] In some embodiments, the thickness of the solid electrolyte layer can be 20μm to 100μm, 30μm to 50μm, etc.

[0375] The following is a description of the positive electrode layer.

[0376] The positive electrode layer can be provided by a pre-fabricated positive electrode sheet.

[0377] The positive electrode sheet can be prepared by a wet process. It can be wet-coated and dried to form a film.

[0378] Unless otherwise stated, the positive electrode layer in this application includes at least a positive electrode active layer.

[0379] Unless otherwise stated in this application, the positive electrode sheet includes at least a positive active layer.

[0380] In this application, unless otherwise specified, the positive electrode active layer includes at least a positive electrode active material, and typically also includes a solid electrolyte material. In this application, unless otherwise specified, the solid electrolyte material in the positive electrode layer may be referred to as "positive electrode electrolyte material".

[0381] The positive electrode active material may be any positive electrode active material known in the art for use in batteries. As a non-limiting example, the positive electrode active material may include one or more of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides include, but are not limited to, one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their modified compounds. Non-limiting examples of lithium-containing phosphates with an olivine structure include, but are not limited to, one or more of lithium iron phosphate, lithium iron phosphate and carbon composites, lithium manganese phosphate, lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium manganese iron phosphate and carbon composites. Non-limiting examples of lithium cobalt oxides may include LiCoO2; non-limiting examples of lithium nickel oxides may include LiNiO2; non-limiting examples of lithium manganese oxides may include LiMnO2, LiMn2O4, etc.; non-limiting examples of lithium nickel cobalt manganese oxides may include LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn0.2 O2 (which can also be abbreviated as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (which can also be abbreviated as NCM 811 ). Non - limiting examples of lithium nickel cobalt aluminum oxide can include LiNi 0.80 Co 0.15 Al 0.05 O2. An example of lithium iron phosphate is LiFePO4 (which can also be abbreviated as LFP). An example of lithium manganese phosphate is LiMnPO4.

[0382] In some embodiments, the positive electrode active material includes one or more of lithium nickel cobalt manganese oxide ternary positive electrode material, lithium nickel cobalt manganese aluminum oxide quaternary positive electrode material, lithium - rich manganese - based positive electrode material, lithium iron phosphate, lithium manganese phosphate, lithium iron manganese phosphate, lithium manganese oxide or nickel manganese acid.

[0383] In this application, unless otherwise specified, the "lithium nickel cobalt manganese oxide ternary positive electrode material" refers to a positive electrode active material composed of Li element, Ni element, Co element, Mn element and O oxygen element.

[0384] In this application, unless otherwise specified, the "lithium nickel cobalt manganese aluminum oxide quaternary positive electrode material" refers to a positive electrode active material composed of Li element, Ni element, Co element, Mn element, Al element and O oxygen element.

[0385] In this application, unless otherwise specified, the "lithium - rich manganese - based positive electrode active material" refers to a positive electrode active material containing Li2MnO3, and optionally containing LiM 7 O2, where M 7 is a transition metal element. Non - restrictively, M 7 can include one or more of transition metal elements such as Ni, Co, Mn, Cr, Fe, Al, Nb, Zr, Mo, Ta, etc. The layered lithium - rich manganese - based positive electrode active material has advantages such as high specific capacity, high voltage platform and easy synthesis. In some embodiments, the chemical formula of the layered lithium - rich manganese - based positive electrode active material is y1(Li2MnO3)·(1 - y1)(LiM 7 O2), where 0 < y1 ≤ 1, and optionally, 0 < y1 < 1. In some embodiments, the lithium - rich manganese - based positive electrode active material is a layered lithium - rich manganese - based positive electrode active material.

[0386] Taking solid-state batteries with lithium-ion active ions as an example, it is understandable that lithium (Li) is intercalated and deintercalated during the charging and discharging process, and the Li content in the positive electrode layer varies depending on the state of discharge. In the exemplary description of the positive electrode active material in this application, unless otherwise specified, the Li content can be the initial state of the material or a non-initial state after charge-discharge cycles. When the positive electrode active material is applied to the positive electrode layer in a solid-state battery system, the Li content in the positive electrode active material contained in the positive electrode layer usually changes after charge-discharge cycles. The Li content can be measured using atomic molar content, but is not limited to this. Regarding "Li content is the initial state of the material," the initial state of the material refers to the state before the positive electrode layer. It is understood that new materials or substances obtained by appropriate modification based on the listed positive electrode active materials are also within the scope of positive electrode active materials. The aforementioned appropriate modification refers to an acceptable modification method for the positive electrode active material, and non-limiting examples include one or more of coating modification and doping modification. In the exemplary description of the positive electrode active material in this application, the oxygen (O) content is usually a theoretical value. Lattice oxygen release will cause changes in the atomic molar content of oxygen, and the actual O content will fluctuate. The O content can be measured in atomic molar content, but is not limited to this.

[0387] Non-limitingly, the mass percentage content of the positive electrode active material in the positive electrode active layer can be ≥70%, or 70% to 94%, further 70% to 90%, and even more preferably 70% to 88%, or any of the following percentages or a range selected from any two of the following percentages: 70%, 72%, 74%, 75%, 76%, 78%, 80%, 82%, 84%, 85%, 86%, 88%, 90%, 92%, 94%, etc.

[0388] The solid electrolyte material in the positive electrode active layer may be any solid electrolyte material known in the art that can be used in the positive electrode layer of a solid-state battery, including but not limited to the solid electrolyte material described in the solid electrolyte layer section.

[0389] The types of solid electrolyte materials present in different film layers of a solid-state battery can be the same or different. For example, the solid electrolyte materials in the positive electrode layer and the solid electrolyte layer can be the same or different. As a non-limiting example, the solid electrolyte materials in different film layers of a solid-state battery can include one or more of the following: sulfide solid electrolytes, halide solid electrolytes, oxide solid electrolytes, and polymer solid electrolytes.

[0390] Non-limitingly, the mass percentage of the positive electrode electrolyte material in the positive electrode active layer can be 5% to 30%, preferably 5% to 20%, further preferably 5% to 15%, and can also be any of the following percentages, or selected from any two of the following percentages: 5%, 6%, 8%, 10%, 12%, 14%, 15%, 16%, 18%, 20%, 22%, 24%, 25%, 30%, etc.

[0391] In some embodiments, the positive electrode active layer optionally includes a conductive agent (which may be referred to as a positive electrode conductive agent). As a non-limiting example, the positive electrode conductive agent may be a carbon conductive agent. Non-limitingly, the carbon conductive agent may include one or more of superconducting carbon, acetylene black, conductive carbon black (SP), Ketjen black (ECP), carbon dots, carbon nanotubes (CNTs), graphene, and carbon fibers. Examples of carbon nanofibers include vapor-grown carbon fiber (VGCF). Non-limitingly, the mass percentage of the positive electrode conductive agent in the positive electrode active layer may be 0–10%, 0.1%–5%, and further 0.5%–2%.

[0392] In some embodiments, the positive electrode active layer optionally includes a binder. The binder in the positive electrode active layer may be referred to as a positive electrode binder. The positive electrode binder may be a binder known in the art for use in positive electrode layers in solid-state batteries. As a non-limiting example, the positive electrode binder may include one or more of the following: polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), polyethylene (PE), etc.

[0393] Typically, the mass percentage of the positive electrode binder in the positive electrode active layer can be 0-5%, optionally 0-3%, and further optionally 0-2%. In some embodiments, the mass percentage of the positive electrode binder in the positive electrode active layer is 0.1%-5%, optionally 0.5%-3%, and further optionally 0.5%-2%.

[0394] In some embodiments, the positive electrode layer includes a positive electrode current collector and a positive electrode active layer disposed on at least one surface of the positive electrode current collector. As a non-limiting example, the positive electrode current collector has two surfaces that are opposite to each other in its own thickness direction, and the positive electrode active layer is disposed on either or both of the two opposite surfaces of the positive electrode current collector.

[0395] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. In the positive electrode current collector, the composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. In the positive electrode current collector, the composite current collector may be obtained by forming a metal material on the polymer material substrate. Non-limiting examples of the metal material in the positive electrode current collector may include at least one of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. Non-limitingly, in the positive electrode current collector, the polymer material substrate may include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0396] In some embodiments, the positive electrode sheet can be prepared by dispersing the components used to prepare the positive electrode sheet, such as positive electrode active material, positive electrode electrolyte material, positive electrode conductive agent, positive electrode binder, and any other components, in a suitable organic solvent to form a positive electrode slurry. Further, the positive electrode slurry is coated onto at least one surface of the positive electrode current collector, and after drying and optionally cold pressing, the positive electrode sheet is obtained. The optional cold pressing process can be performed using a cold press. The surface of the positive electrode current collector coated with the positive electrode slurry can be a single surface or both surfaces of the positive electrode current collector. The solid content of the positive electrode slurry can be 50wt% to 80wt%. When coating the positive electrode slurry, the coating surface density on both sides of the positive electrode current collector, based on dry weight (excluding solvent), can be, but is not limited to, 15 mg / cm³. 2 ~50mg / cm 2 15mg / cm 2 ~35mg / cm 2 .

[0397] In solid-state batteries, the compaction density of the positive electrode layer can be, but is not limited to, 3.0 g / cm³. 3 ~3.6g / cm 3 3.3g / cm³ is an option. 3 ~3.5g / cm 3 In this application, unless otherwise stated, the compaction density of the cathode layer is equal to the ratio of the mass to the volume of the cathode layer.

[0398] For a method of assembling a positive electrode and a solid electrolyte membrane into a solid-state battery, please refer to the third aspect of this application.

[0399] In some embodiments, the solid-state battery may include an outer packaging. This outer packaging can be used to encapsulate the aforementioned solid-state battery cell.

[0400] In some embodiments, the outer packaging of a solid-state battery can be a rigid shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of a solid-state battery can also be a soft pack, such as a pouch-type soft pack. The material of the soft pack can be plastic; further, non-limiting examples of plastics may include one or more of polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0401] This application does not impose any particular limitation on the shape of the solid-state battery cell; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 2 shows a square solid-state battery cell 5 as an example.

[0402] In some embodiments, referring to FIG3, the outer packaging may include a housing 51 and a cover plate 53. The housing 51 may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 can be placed over the opening to close the receiving cavity. A solid-state battery cell 52 is encapsulated within the receiving cavity. The number of solid-state battery cells 52 contained in the solid-state battery cell 5 may be one or more, which can be selected by those skilled in the art according to actual needs.

[0403] Solid-state batteries can be battery device 4 or battery pack 1.

[0404] The battery device includes at least one solid-state battery cell. The number of solid-state battery cells in the battery device can be one or more, and those skilled in the art can select an appropriate number according to the application and capacity of the battery device.

[0405] Figure 4 shows a battery device 4 as an example. Referring to Figure 4, in the battery device 4, multiple solid-state battery cells 5 can be arranged sequentially along the length of the battery device 4. Of course, they can also be arranged in any other arbitrary manner. Furthermore, the multiple solid-state battery cells 5 can be fixed in place by fasteners.

[0406] Optionally, the battery device 4 may also include a housing with a receiving space in which a plurality of solid-state battery cells 5 are housed.

[0407] In some embodiments, the battery devices described above can also be assembled into a battery pack, and the number of battery devices contained in the battery pack can be one or more. Those skilled in the art can select an appropriate number according to the application and capacity of the battery pack.

[0408] Figures 5 and 6 illustrate a battery pack 1 as an example. Referring to Figures 5 and 6, the battery pack 1 may include a battery compartment and multiple battery devices 4 disposed within the battery compartment. The battery compartment includes an upper compartment 2 and a lower compartment 3, with the upper compartment 2 covering the lower compartment 3 to form a closed space for accommodating the battery devices 4. The multiple battery devices 4 can be arranged in any manner within the battery compartment.

[0409] In a second aspect of this application, a negative electrode sheet is provided, comprising a negative current collector, a second carbon layer and a first carbon layer stacked sequentially, wherein the definitions of the first carbon layer and the second carbon layer are provided in the first aspect of this application.

[0410] In some embodiments, a negative electrode sheet is provided, which includes a negative current collector and a second carbon layer and a first carbon layer sequentially stacked on at least one side of the negative current collector.

[0411] The negative electrode includes a negative current collector and a composite carbon layer. The composite carbon layer includes a second carbon layer and a first carbon layer, with the second carbon layer located between the negative current collector and the first carbon layer.

[0412] Unless otherwise specified, the second carbon layer comprises a second carbon material, and the first carbon layer comprises a first carbon material. The definitions of the first carbon material and the second carbon material can be found in the first aspect of this application.

[0413] In some embodiments, the first carbon material is a porous carbon material, and the pore volume fraction of the second carbon material is less than or equal to 5%; at least one of the ion diffusion coefficient and the pore volume fraction of the first carbon material is greater than that of the second carbon material; the D of the second carbon material... v At least one of 50 and average particle size is smaller than that of the first carbon material.

[0414] In some embodiments, a negative electrode sheet is provided, comprising a negative electrode current collector, a second carbon layer, and a first carbon layer stacked sequentially. The second carbon layer comprises a second carbon material, and the first carbon layer comprises a first carbon material. The first carbon material is a porous carbon material, and the pore volume fraction of the second carbon material is less than or equal to 5%. At least one of the ion diffusion coefficient and the pore volume fraction of the first carbon material is greater than that of the second carbon material. The D0 of the second carbon material is... v At least one of 50 and average particle size is smaller than that of the first carbon material.

[0415] The definition of "pore volume fraction" in the material is consistent with the first aspect of this application, referring to the percentage of the total pore volume in the particles relative to the particle volume.

[0416] This negative electrode sheet allows for the sequential placement of a second carbon layer comprising a second carbon material and a first carbon layer comprising a first carbon material between the negative electrode current collector and the solid electrolyte layer in a solid-state battery. The first carbon material near the solid electrolyte layer is a porous carbon material with a high lithium-ion diffusion coefficient and / or a high pore volume fraction, providing abundant interfaces and a good electrolyte-first carbon layer interface. This allows the first carbon layer to quickly attract and mediate the rapid transport of active ions to the negative electrode current collector. The second carbon material near the negative current collector has no obvious pore structure (corresponding to a very low pore volume fraction) and a low particle size, forming a dense and flat second carbon layer. This provides a good negative electrode current collector-second carbon layer interface, which is beneficial for inducing uniform deposition of active ions at the negative electrode current collector. Based on the aforementioned multiple effects, through multi-level interface optimization between the solid electrolyte layer-first carbon layer-second carbon layer-negative electrode current collector, the deposition behavior of active ions can be optimized, significantly suppressing local deposition and deposition inhomogeneity of the negative electrode, and significantly suppressing dendrite formation in the negative electrode. Therefore, the cycle life of the solid-state battery can be significantly extended.

[0417] It is understandable that by suppressing the formation of dendrites on the negative electrode, short circuits in the battery can also be suppressed, thereby improving the reliability of solid-state batteries.

[0418] In some implementations, the negative electrode sheet satisfies one or both of the following characteristics:

[0419] (k1) The negative electrode current collector includes the features of the negative electrode current collector in the solid-state battery described in the first aspect of this application;

[0420] (k2) The second carbon layer includes the features of the second carbon layer in the solid-state battery described in the first aspect of this application;

[0421] (k3) The first carbon layer includes the features of the first carbon layer in the solid-state battery described in the first aspect of this application.

[0422] In a third aspect of this application, a method for preparing a solid-state battery is provided, which can be used to prepare the solid-state battery of the first aspect of this application.

[0423] In some embodiments, a method for preparing a solid-state battery is provided, which includes the following steps:

[0424] S100: A positive electrode, a solid electrolyte membrane, and a negative electrode are stacked sequentially to prepare a laminate; wherein, the solid electrolyte membrane includes a solid electrolyte material, and the definition of the negative electrode can be found in the second aspect of this application. The negative electrode includes a negative current collector, a second carbon layer, and a first carbon layer stacked sequentially, with the second carbon layer located between the first carbon layer and the solid electrolyte membrane.

[0425] S200: Under heating conditions, the laminate is densified to prepare a solid-state battery.

[0426] In some embodiments, the negative electrode sheet includes a negative current collector, a second carbon layer, and a first carbon layer stacked sequentially. The second carbon layer includes a second carbon material, and the first carbon layer includes a first carbon material. The first carbon material is a porous carbon material, and the pore volume fraction of the second carbon material is less than or equal to 5%. At least one of the ion diffusion coefficient and the pore volume fraction of the first carbon material is greater than that of the second carbon material. The D0 of the second carbon material is... v At least one of 50 and average particle size is smaller than that of the first carbon material.

[0427] After densification treatment, the solid-solid interface contact quality in the overall structure of solid-state batteries can be improved. This can not only improve the solid-solid interface between different structural layers and form a good contact between the positive electrode layer, solid electrolyte layer, first carbon layer, second carbon layer and negative electrode current collector, but also improve the solid-solid interface between solid particles in each structural layer, including the solid-solid interface between the first carbon materials in the first carbon layer and the solid-solid interface between the second carbon materials in the second carbon layer.

[0428] In step S100, the first carbon layer is positioned between the solid electrolyte membrane and the second carbon layer.

[0429] In step S100, the laminate includes a negative electrode current collector, a second carbon layer, a first carbon layer, a solid electrolyte membrane, and a positive electrode sheet stacked sequentially. Correspondingly, after densification, the resulting solid-state battery includes a negative electrode current collector, a second carbon layer, a first carbon layer, a solid electrolyte layer, and a positive electrode layer stacked sequentially. After densification, the solid electrolyte membrane corresponds to the solid electrolyte layer in the solid-state battery, and the positive electrode sheet corresponds to the positive electrode layer in the solid-state battery.

[0430] In some embodiments, the solid electrolyte membrane comprises at least a solid electrolyte material and optionally a third binder.

[0431] In some embodiments, the negative electrode sheet is prepared by a method including the following steps: a second carbon layer and a first carbon layer are sequentially formed on at least one side surface of the negative electrode current collector.

[0432] In some embodiments, the method for fabricating solid-state batteries satisfies one or more of the following characteristics (any numerical parameter of the following characteristics may also be selected from any suitable value or range in the context):

[0433] (m1) The negative electrode sheet is prepared by a method including steps S12 and S14:

[0434] S12: A second negative electrode slurry including a second carbon material is coated onto at least one side surface of the negative electrode current collector and dried to form a second carbon layer on at least one side surface of the negative electrode current collector.

[0435] S14: The first negative electrode slurry, including the first carbon material, is coated onto the second carbon layer and dried to form the first carbon layer on the second carbon layer.

[0436] (m2) The negative electrode sheet is the negative electrode sheet described in any embodiment of the second aspect of this application;

[0437] (m3) The heating conditions are 50℃~100℃, which can be selected as 80℃~100℃, or any of the following temperatures or a range composed of any two temperatures: 50℃, 60℃, 70℃, 80℃, 90℃, 100℃, etc.

[0438] (m4) The densification pressure is 300MPa to 600MPa, and can be selected as 400MPa to 600MPa. It can also be any of the following pressures or a range consisting of any two pressures: 300MPa, 350MPa, 400MPa, 450MPa, 500MPa, 550MPa, 600MPa, etc.

[0439] In this application, the "first negative electrode slurry" includes at least a first carbon material and an organic solvent.

[0440] In this application, the "second negative electrode slurry" includes at least a second carbon material and an organic solvent.

[0441] In this application, the terms "first" and "second" in "first negative electrode slurry" and "second negative electrode slurry" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features.

[0442] In some embodiments, the first negative electrode slurry may optionally include a first binder.

[0443] In some embodiments, the second negative electrode slurry may optionally include a second binder.

[0444] The definitions of the first carbon material, the second carbon material, the first binder, and the second binder can be found in the first aspect of this application, and the corresponding amounts can also be found in the compositional description of the first carbon layer and the second carbon layer in the first aspect of this application.

[0445] Densification under heating conditions can be high-temperature densification. The temperature conditions for high-temperature densification can be 50℃~100℃, can be selected from 80℃~100℃, or can be any of the following temperatures or a range composed of any two of the following temperatures: 50℃, 60℃, 70℃, 80℃, 90℃, 100℃, etc.

[0446] The organic solvents in the first and second negative electrode slurries can be the same or different; for example, they can be N-methylpyrrolidone (NMP).

[0447] In some embodiments, the negative electrode sheet is prepared by a method including steps S12' and S14':

[0448] S12': The second negative electrode slurry is coated on at least one side surface of the negative electrode current collector and dried to form a second carbon layer on at least one side surface of the negative electrode current collector.

[0449] S14': The first negative electrode slurry is coated onto the second carbon layer and dried to form the first carbon layer on the second carbon layer.

[0450] The first carbon material and the second carbon material can be selected from commercially available products that conform to the carbon material described in the first aspect of this application, or they can be obtained by adjusting relevant parameters based on existing methods according to the feature description of the first aspect of this application to obtain the first carbon material and the second carbon material described in the first aspect of this application.

[0451] Taking hard carbon as the first carbon material as an example, hard carbon with a porous structure can be prepared by the following method:

[0452] (1) Selection of carbon source. The carbon source may include one or more of resins, organic polymers, carbon black, and biomass carbon. Non-limiting examples of resins may include one or more of phenolic resins, epoxy resins, polyfurfuryl alcohol resins, etc.; non-limiting examples of organic polymers may include one or more of polyvinyl alcohol (PVA), polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), etc. Non-limiting examples of biomass carbon may include one or more of plant residues and shells, etc.

[0453] (2) Synthesis of hard carbon precursor.

[0454] A carbon source and a pore-forming agent are mixed and pre-carbonized under a protective gas atmosphere to obtain a hard carbon precursor (the obtained hard carbon precursor is a porous carbon precursor material). The obtained porous carbon precursor material is then crushed and carbonized again under a protective gas atmosphere to obtain hard carbon. The carbonization temperature can be between 1000℃ and 1600℃, but is not limited to this.

[0455] In a non-limiting manner, the carbon source for preparing hard carbon precursors may include one or more of the following: coal tar, coal pitch, petroleum residue, petroleum pitch, synthetic pitch, anthracite, aliphatic organic compounds, organic compounds containing carbonyl groups, organic compounds containing benzene rings, synthetic resins, epoxy resins, phenolic resins, sucrose, cellulose, lignin, glucose, starch, and gelatin.

[0456] Taking the resin as a carbon source as an example, the resin and porogen are mixed to obtain a preliminary mixture, which is then cured and molded before being vulcanized and dried to crosslink the resin.

[0457] Non-limitingly, the pore-forming agent (i.e., the pore-forming agent) may include one or more of the following: water vapor, potassium hydroxide, sodium hydroxide, calcium hydroxide, calcium oxide, magnesium oxide, magnesium hydroxide, melamine, aluminum oxide, polymers, etc. In some embodiments, the pore-forming agent is water vapor, which is beneficial for the formation of mesopores and micropores.

[0458] The curing process can include injection molding, spraying, freeze drying, etc.

[0459] (3) Pyrolytic carbonization. The hard carbon precursor is subjected to high-temperature pyrolytic carbonization. The temperature for high-temperature pyrolytic carbonization can be 1000℃~1400℃, or any of the following temperatures or a range selected from any two of the following temperatures: 1000℃, 1050℃, 1100℃, 1150℃, 1200℃, 1250℃, 1300℃, 1350℃, 1400℃, etc.

[0460] (4) Post-processing: After pyrolysis and carbonization, some post-processing steps may be required, such as washing, crushing, and sieving.

[0461] For example, by steps such as crushing and sieving, the particle size and particle size distribution of the first carbon material can be controlled, and the D of the first carbon material can be controlled. v One or more of the following parameters: 50 or average particle size, SPAN1, specific surface area, and powder compaction density at 5 tons of pressure.

[0462] For example, by adjusting parameters such as the type and amount of pore-forming agent and pore-forming process conditions, the porosity inside the first carbon material can be controlled, thereby adjusting parameters such as the pore volume fraction, ion diffusion coefficient, and the proportion of mesopores / or micropores in the pore structure of the first carbon material.

[0463] Taking acetylene black as the second carbon material as an example, acetylene black can be prepared by the following method:

[0464] (1) Preparation of acetylene gas. The calcium carbide method is commonly used: calcium carbide is added to an acetylene generator and reacts with water to produce acetylene gas. The reaction equation is: CaC2 + 2H2O → C2H2 + Ca(OH)2.

[0465] (2) Purification of acetylene gas: Acetylene gas coming out of the acetylene generator needs to be condensed, washed and purified to ensure its purity.

[0466] (3) Preparation of acetylene black: Purified acetylene gas is introduced into a preheated pyrolysis furnace and subjected to thermal pyrolysis in the absence of air to produce acetylene black and hydrogen. Since acetylene pyrolysis is an exothermic reaction, this process can continue.

[0467] (4) Collection and treatment of acetylene black: The generated acetylene black and hydrogen are discharged from the bottom of the pyrolysis furnace, cooled and conveyed to a grinding mill for crushing and removal of coke lumps. Then, the acetylene black is classified by air separation through a cyclone separator to obtain acetylene black of the desired particle size. The prepared acetylene black has a basically non-porous structure and can be included in the category of non-porous carbon materials.

[0468] For example, the average diameter of primary particles in the second carbon material can be controlled by adjusting parameters such as the temperature and time of the pyrolysis reaction. Similarly, the Dg of the second carbon material can be controlled by adjusting relevant parameters of air classification. v One or more parameters can be selected from 50 or average particle size, specific surface area, and powder compaction density under 5 tons of pressure. Ultrasonic vibration sieving can also be used to more precisely control the size and distribution of the second carbon material, thereby adjusting the specific surface area and powder compaction density under 5 tons of pressure.

[0469] For a second carbon material containing doped elements, those skilled in the art can employ suitable methods. For example, the doping elements can be incorporated in powder form during the coating process to form the second carbon layer.

[0470] In some embodiments, the solid-state battery preparation method produces the solid-state battery described in the first aspect of this application.

[0471] In a fourth aspect of this application, an electrical device is provided, comprising at least one of the solid-state battery described in the first aspect of this application, the negative electrode sheet described in the second aspect of this application, and a solid-state battery prepared by the method for preparing a solid-state battery described in the third aspect of this application.

[0472] In some embodiments, the electrical device includes at least one of the solid-state batteries of any of the embodiments provided in this application.

[0473] In a non-limiting sense, solid-state batteries can be used as a power source for electrical devices or as an energy storage unit for electrical devices. Electrical devices can include, but are not limited to, mobile devices, electric vehicles, electric trains, ships and satellites, energy storage systems, etc. Mobile devices can be, for example, mobile phones, laptops, etc.; electric vehicles can be, for example, pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, electric motorcycles, power tools, etc., but are not limited to these. This electrical device can also be applied to military equipment, aerospace, and other fields, and can also be applied to energy storage power systems such as hydroelectric, thermal, wind, and solar power plants.

[0474] As an electrical device, solid-state batteries can be selected based on its usage requirements.

[0475] Figure 7 shows an example of an electrical device 6. This electrical device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the high power and high energy density requirements of this electrical device for solid-state batteries, a battery device or battery pack can be used.

[0476] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a thin and light design and can use solid-state batteries as their power source.

[0477] The following describes some embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where the technology or conditions are not specified in the embodiments, they are performed according to the description above, or according to the technology or conditions described in the literature in this field, or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially, or can be synthesized from commercially available products using conventional methods.

[0478] In the following examples, room temperature refers to 20°C to 30°C.

[0479] It should be noted that the following embodiments and examples use all-solid-state batteries as non-limiting examples of solid-state batteries, and further use all-solid-state lithium-ion secondary batteries as an example.

[0480] In the following examples, unless otherwise specified, the use of organic solvents to disperse sulfide-based solid electrolyte materials is involved. The organic solvent may be one or more of p-xylene, trimethylbenzene, butyl butyrate, heptane, etc., and may further be p-xylene.

[0481] In the following embodiments and comparative examples, unless otherwise stated, the steps involving sulfide solid electrolytes and materials or films containing them are carried out in an argon atmosphere.

[0482] In the following examples, unless otherwise specified, the parameters involved can be confirmed and / or adjusted by referring to the test methods described above. For example, parameters involving the ion diffusion coefficient of the first and second carbon materials, the pore volume fraction and pore volume of the first and second carbon materials, and the average particle size and D of the first carbon material. v 50. D v 90. D v Size parameters such as 10 and SPAN value relate to the average particle size and D of the second carbon material. v 50. Dimensional parameters such as the average diameter of primary particles, specific surface area of ​​the first and second carbon materials, pore structure size and distribution of the first carbon material (e.g., the proportion of mesopores and / or micropores in the pore structure, pore volume, etc.), compaction density of the first and second carbon materials under 5 tons of pressure, material types of the first and second carbon materials, mass percentage of the first carbon material, second carbon material, and solid electrolyte material in the corresponding first carbon layer, second carbon layer, and solid electrolyte layer, types of the first binder, second binder, and third binder and their mass percentage in the corresponding first carbon layer, second carbon layer, and solid electrolyte layer, thickness, thickness ratio, and sum of thickness of the first and second carbon layers, elemental composition of the positive electrode active body material, etc.

[0483] I. Testing of first and second carbon materials.

[0484] From commercially available materials and the first and second carbon materials obtained by the aforementioned preparation methods, the desired first and second carbon materials are selected based on the test results of relevant parameters. The selection criteria can be found in Table 1.

[0485] The detection methods for the first carbon material and the second carbon material in the following embodiments include:

[0486] (I) Scanning Electron Microscopy (SEM)

[0487] Instrument model: Hitachi SU8600 field emission scanning electron microscope.

[0488] 1. Test parameters: average particle size of the first carbon material and the second carbon material.

[0489] Samples to be tested: Powder samples of the first carbon material and the second carbon material.

[0490] Test method: The powder sample to be tested is adhered to conductive adhesive for SEM testing at a magnification of 10000X to 50000X. At least 20 particles are selected for particle size analysis. The maximum diameter of the selected particles in each direction of the SEM image is recorded as the "particle size". The average particle size of the analyzed particles is recorded as the "average particle size" of the sample.

[0491] 2. The pore structure of the first carbon material and the proportion of pore structures of different sizes, pore volume fraction and pore volume.

[0492] Samples to be tested: Powder samples of the first carbon material and the second carbon material.

[0493] Test method: Please refer to the previous text.

[0494] The proportion of mesopores and micropores in the pore structure is defined in GB / T 21650.2-2008.

[0495] The pore volume fraction was tested according to GB / T24586-2009, using the gas displacement method. The testing instrument was a Micromeritics AccuPycII1340 true density meter. The pore volume fraction of carbon materials was calculated as (V1-V2) / V1×100%, where V1 is the apparent volume of the sample and V2 is the true volume. Nitrogen gas was used for the test. The pore volume of carbon materials was calculated as (V1-V2) / M. C V1 is the apparent volume of the sample, V2 is the actual volume of the sample, and M... C Nitrogen gas was used as the test gas to measure the mass of the carbon material to be tested.

[0496] (II) Laser Particle Size Analyzer Analysis

[0497] Testing instrument: MasterSizer3000 laser particle size analyzer.

[0498] Samples to be tested: Powder samples of the first carbon material and the second carbon material.

[0499] Parameter to be measured: D v 50. D v 90. D v 10; In addition, the SPAN value = (D v 90-D v 10) / D v 50.

[0500] Test Method: Take an appropriate amount of the sample to be tested, add deionized water as solvent (sample concentration can be controlled to meet 8%~12% light-blocking requirements), and sonicate for 5 minutes (53KHz / 120W) to fully disperse the sample. Turn on the laser particle size analyzer, clean the optical path system, and automatically test the background. Stir the sonicated suspension to ensure uniform dispersion, and add the uniformly dispersed sample to the injection cell. After the sample stabilizes for 5s~10s, start the test. After the sample is poured into the injection tower, it circulates with the solution to the test optical path system. Under the irradiation of the laser beam, the particle size distribution characteristics can be obtained by receiving and measuring the energy distribution of the scattered light. Based on the test data, a particle size volume distribution map is plotted, and the D value is obtained from the distribution map. v 50. Dv 90. D v 10. To avoid agglomeration during the drying process affecting particle size testing, a dispersion test was performed on a sample that had been washed with ethanol and then moistened. Ethanol can be used as the washing reagent.

[0501] (III) Ion diffusion coefficient

[0502] Materials to be tested: Powder samples of first carbon material and second carbon material.

[0503] Test method: GITT method. The diffusion behavior of ions in the test material is measured through a series of "pulse + constant current + relaxation" processes. More detailed steps include: first, applying a small current pulse, then turning off the current, recording the potential change, analyzing the polarization information of the electrode reaction based on this, and then calculating the diffusion coefficient.

[0504] The test temperature was 25℃. The test material was ground into a powder microelectrode. The powder microelectrode was then connected to an electrochemical workstation for coulometric titration. A pulsed current of 20 μA was used, with a titration time of 1 hour followed by a 4-hour interval (Note: To compare the effect of pulsed current and time, parallel experiments of 10 μA for 10 minutes can be performed). The GITT curve was obtained. The ion diffusion coefficient D was calculated using the following formula:

[0505] Where D is the ion diffusion coefficient; I0 ​​is the applied pulse current of 20 μA; V m dE / dx is the molar volume of the analyte, i.e., the volume of one mole of the substance; F is the Faraday constant; A is the electrode surface area, the transported ion is lithium ion, and n is 1; dE / dx is the slope of the coulometric titration curve, i.e., the slope of the open-circuit potential versus Li concentration curve at a certain concentration in the electrode; dE / d(t 1 / 2 ) represents the polarization voltage relative to t 1 / 2 The slope of the curve.

[0506] (iv) Specific surface area of ​​the first carbon material and the second carbon material.

[0507] Testing instrument: Tri-Star3020 specific surface area and pore size analyzer from 5Micromeritics, USA.

[0508] Test method: Refer to GB / T19587-2017, use the nitrogen adsorption specific surface area analysis test method, and calculate it using the BET (Brunauer Emmett Teller) method.

[0509] (v) Powder compaction density of the first and second carbon materials under 5 tons of pressure.

[0510] Referring to standard GB / T24533-2009, the testing equipment was a UTM7305 compaction density tester.

[0511] The test method is as follows: Weigh 201.0000±0.0500g of sample and place it in a test mold with a diameter of 13mm (e.g., CARVER#3619). Then, place the powder sample in the test equipment. Select the following test conditions: 5 tons pressure, pressure increase rate 10mm / min, pressure increase holding time 30s, pressure release rate 30mm / min, and pressure release holding time 10s. Measure the compacted density of the sample when the pressure is released. The powder compacted density of the sample = sample mass / (mold area × sample thickness) to obtain the powder compacted density under 5 tons pressure.

[0512] II. Preparation of negative electrode sheets and all-solid-state batteries

[0513] Example 1.

[0514] 1. Preparation of negative electrode sheet

[0515] Preparation of the second negative electrode slurry: The second carbon material acetylene black and the binder polyvinylidene fluoride (PVDF) are mixed at a mass ratio of 95%:5% and dispersed evenly in the solvent N-methylpyrrolidone (NMP) to prepare the first negative electrode slurry with a solid content of about 25 wt%.

[0516] Forming the second carbon layer: The second negative electrode slurry is coated on both sides of the copper foil of the negative electrode current collector and dried to form a second carbon layer with a thickness of about 5 micrometers (μm).

[0517] Preparation of the first negative electrode slurry: The first carbon material, hard carbon, and the binder, polyvinylidene fluoride (PVDF), are mixed at a mass ratio of 95%:5% and dispersed evenly in the solvent N-methylpyrrolidone (NMP) to prepare the first negative electrode slurry with a solid content of approximately 18 wt%.

[0518] Forming the first carbon layer: The first negative electrode slurry is coated onto the second carbon layers on both sides and dried to form a first carbon layer with a thickness of about 5 micrometers (μm), thus preparing a negative electrode sheet with a composite carbon layer. The composite carbon layer includes a second carbon layer and a first carbon layer, with the second carbon layer located between the negative electrode current collector and the first carbon layer.

[0519] In this example, the second carbon material is hard carbon, and the first carbon material is acetylene black;

[0520] 2. Preparation of the positive electrode sheet

[0521] The positive electrode active material (NCM) 811The positive electrode electrolyte material (sulfide solid electrolyte Li6PS5Cl), conductive agent (vapor-grown carbon fiber VGCF), and binder polytetrafluoroethylene (PTFE) were weighed and mixed in a mass ratio of 70:20:5:5, added to the solvent pseudotrimethylbenzene, and mixed thoroughly to prepare a positive electrode slurry with a solid content of 65wt%. The positive electrode slurry was coated on both sides of the positive electrode current collector aluminum foil (with consistent coating on both sides), rolled, and cut to obtain the positive electrode sheet. (Based on dry weight, deducting solvent content).

[0522] 3. Preparation of solid electrolyte membranes

[0523] The solid electrolyte material (sulfide solid electrolyte Li6PS5Cl) and the binder polytetrafluoroethylene (PTFE) were mixed at a mass ratio of 99:1, ground and dispersed evenly, and then pressed to obtain a solid electrolyte membrane with a thickness of about 60 μm.

[0524] 4. Assembly of all-solid-state batteries

[0525] The cells are assembled in the order of "positive electrode - solid electrolyte membrane - negative electrode" and then subjected to high-temperature densification at 80℃ and 500MPa for 10 minutes to prepare an all-solid-state battery, taking a pouch battery as an example.

[0526] In Example 1, the first carbon material, hard carbon, has a pore volume fraction of 43% and a pore volume of approximately 0.3 cm³. 3 / g, mesopores (2-50nm) account for approximately 33%, micropores (<2nm) account for approximately 65%, macropores (>50nm) account for approximately 2%, and the ion diffusion coefficient is approximately 3.8×10 -9 cm 2 / s, D v The particle size is approximately 1 μm, the average particle size is approximately 0.95 μm, the SPAN1 value is approximately 2.9, and the specific surface area (BET) is approximately 382 m². 2 / g, the compacted density of the powder under 5 tons of pressure is approximately 0.86 g / cm³. 3 The second carbon material, acetylene black, has a pore volume fraction of less than 1% and an ion diffusion coefficient of approximately 5.5 × 10⁻⁶. -10 cm 2 / s, the average diameter of primary particles is approximately 52nm, D v 50 nm is approximately 65 nm, and the specific surface area (BET) is approximately 43 m². 2 / g, the compacted density of the powder under 5 tons of pressure is approximately 0.78 g / cm³. 3 The SEM and TEM images of the second carbon material, acetylene black, can be found in Figures 8-9.

[0527] Examples 2-14 use the same method as Example 1 to prepare negative electrode sheets and all-solid-state batteries. The difference is that one or more parameters, such as the raw materials of the first carbon material, the raw materials of the second carbon material, the thickness of the first carbon layer and the thickness ratio of the second carbon layer, are different. The description is as follows. The remaining operation steps are the same as in Example 1.

[0528] Examples 2-5 involve changing at least one parameter in the pore volume fraction (correspondingly changing the pore volume) and the proportion of mesopores and micropores in the pore structure of the first carbon material. Examples 2-3 primarily adjust the pore volume fraction of the first carbon material. Examples 4-5 primarily adjust the proportion of mesopores and micropores in the pore structure.

[0529] In Example 2, the hard carbon had a pore volume fraction of 32% and an average particle size of about 1 μm.

[0530] In Example 3, the hard carbon had a pore volume fraction of 54% and an average particle size of approximately 1 μm.

[0531] In Example 4, the proportions of mesopores, micropores, and macropores in the first carbon material, hard carbon, were 9%, 78%, and 19%, respectively. The pore volume fraction of hard carbon was 45%, and the average particle size was about 1 μm.

[0532] In Example 5, the proportions of mesopores, micropores, and macropores in the first carbon material, hard carbon, were 59%, 21%, and 20%, respectively. The pore volume fraction of hard carbon was 44%, and the average particle size was about 1 μm.

[0533] Example 6: The source of hard carbon in the first carbon material was changed, and the ion diffusion coefficient of the hard carbon was approximately 1.1 × 10⁻⁶. -9 cm 2 / s, with an average particle size of approximately 1μm.

[0534] Example 7: The source of hard carbon in the first carbon material was changed, and the pore volume fraction of the hard carbon was about 25%, with an average particle size of about 1 μm.

[0535] Examples 8-9: Changing the average particle size of the first carbon material, D v 50. Changes in SPAN value, specific surface area (BET), and compaction density of powder under 5 tons of pressure.

[0536] In Example 8, the hard carbon had an average particle size of about 500 nm and a pore volume fraction of about 44%.

[0537] In Example 9, the average particle size of the hard carbon was about 1.97 μm, and the pore volume fraction of the hard carbon was about 43%.

[0538] Example 10 mainly changed the specific surface area of ​​the acetylene black in the second carbon material, using a specific surface area of ​​25m². 2 / g of carbon black, with a pore volume fraction of about 2% and an average primary particle diameter of about 100nm.

[0539] Examples 11-12: The average primary particle diameter of the second carbon material, acetylene black, was changed, D v 50. The corresponding changes in specific surface area (BET) and compaction density of powder under 5 tons of pressure.

[0540] In Example 11, the average diameter of the primary particles of the second carbon material, acetylene black, is 26 nm.

[0541] In Example 12, the average diameter of the primary particles of the second carbon material, acetylene black, is 87 nm.

[0542] Examples 13-14 involve changing the thickness and thickness ratio of the first carbon layer and the second carbon layer.

[0543] Example 13: The thickness ratio of the first carbon layer to the second carbon layer is 3:1, and the total thickness is 10 μm.

[0544] Example 14: The thickness ratio of the first carbon layer to the second carbon layer is 1:3, and the total thickness is 10 μm.

[0545] Comparative Example 1 used essentially the same method as Example 1 to prepare the negative electrode and the all-solid-state battery, except that the first carbon layer, which included porous carbon material, was omitted, and only the second carbon layer, which included acetylene black, was retained. The remaining operating steps were the same as in Example 1.

[0546] Comparative Example 2 used essentially the same method as Example 1 to prepare the negative electrode and the all-solid-state battery, except that the second carbon layer was omitted, meaning only the first carbon layer, including hard carbon, was retained. The remaining steps were the same as in Example 1.

[0547] Comparative Example 3 used essentially the same method as Example 1 to prepare the negative electrode sheet and the all-solid-state battery, except that the order of the first carbon layer and the second carbon layer was changed. First, the first negative electrode slurry (including hard carbon) from Example 1 was coated, and then the second negative electrode slurry (including acetylene black) from Example 1 was coated. The remaining operation steps were the same as in Example 1.

[0548] Comparative Example 4 used essentially the same method as Example 1 to prepare the negative electrode and the all-solid-state battery, except that the second carbon material was replaced with porous graphene with a pore volume fraction of approximately 8%, instead of a carbon material with a high pore volume fraction. The remaining operating steps were the same as in Example 1.

[0549] Comparative Example 5 used essentially the same method as Example 1 to prepare the negative electrode and the all-solid-state battery, the difference being that the first carbon material and the second carbon material were artificial graphite from the same source, with a pore volume fraction of approximately 20% and an ion diffusion coefficient of approximately 1 × 10⁻⁶. -9 cm 2 / s, with an average particle size of approximately 0.1 μm. The remaining operating steps are the same as in Example 1.

[0550] III. Test Analysis Methods

[0551] (a) First carbon layer and second carbon layer

[0552] 1. Thickness of the first carbon layer and the second carbon layer

[0553] Test instrument: Field emission scanning electron microscope (SEM), model: Hitachi Su8600.

[0554] The solid-state battery cell was cut along its thickness direction using a CP ion beam polisher (ITACHI IM4000II polisher) to obtain a longitudinal cross-section. SEM observation was performed to measure the thickness of the first and second carbon layers, and then the thickness ratio of the first and second carbon layers was calculated.

[0555] (ii) Electrochemical performance.

[0556] The test temperature can range from -20℃ to 60℃, and the test pressure can range from 0 to 10MPa.

[0557] For each of Examples 1-18 and Comparative Examples 1-5, the test temperature was 45°C and the test pressure was 5 MPa.

[0558] Test method:

[0559] (1) Cyclic performance test:

[0560] The battery under test was subjected to charge-discharge cycles. The first two cycles were performed using a 0.1C rate for formation, followed by a long cycle using 1 / 3C.

[0561] Detailed test: 0.1C charging - 0.1C discharging - 0.33C charging - 0.33C discharging.

[0562] At 25℃, the battery under test was charged to 4.3V at a constant current of 0.1C, left to rest for 10 minutes, and then discharged to 2.6V at a constant current of 0.1C, left to rest for 5 minutes. This constitutes one charge-discharge cycle. The discharge capacity at this point is recorded as C0. This charge-discharge cycle is repeated for the same battery, and the discharge capacity Cn of the 1st, 2nd, ... nth cycle is recorded. The capacity retention rate P after 100 cycles is also recorded. 100 =C100 / C0×100%. The first two cycles are performed using a charge-discharge rate of 0.1C for formation, followed by a long cycle at 0.33C.

[0563] SOC (State of Charge) indicates the state of charge. When "SOC = 0", it means that the battery is fully discharged, and when "SOC = 100%", it means that the battery is fully charged.

[0564] The first coulombic efficiency of the battery under test can be obtained by dividing the first discharge capacity obtained at 0.1C by the first charge capacity.

[0565] The test results are recorded as "first-cycle discharge capacity", "first-cycle coulombic efficiency", and "capacity retention rate P". 100 ".

[0566] (2) Uniformity of lithium deposition

[0567] After the cycle performance test, the solid-state battery cell was removed and cut along the thickness direction using a CP ion beam polisher (ITACHI IM4000II polisher) to obtain a longitudinal cross-section. The uniformity of the lithium deposition layer thickness, the presence and severity of lithium dendrites were then observed. A more uniform lithium deposition layer thickness indicates more uniform lithium deposition.

[0568] (3) Ratio performance test:

[0569] The battery under test was subjected to rate tests at 0.1C, 0.2C, 0.5C, 1C, 2C, and 0.1C. After charging at 0.1C, it was discharged at different rates.

[0570] At 25℃, the solid-state battery under test was first charged to 4.3V (vs. Li+ / Li) at a rate of 0.1C, allowed to stand for 5 minutes, and then discharged to 2.3V (vs. Li+ / Li) at a rate of 0.1C. The solid-state battery under test was then charged and discharged sequentially at rates of 0.1C, 0.2C, 0.5C, 1C, 2C, and 0.1C, with each rate cycled for 3 times. The charging capacity and discharging capacity of each cycle were recorded.

[0571] IV. Test Analysis Results

[0572] Taking hard carbon as the first carbon material and acetylene black as the second carbon material as an example, compared with Comparative Examples 1-5, the all-solid-state batteries prepared in Examples 1-14 all exhibit significantly extended cycle life. Furthermore, lithium deposition uniformity is significantly improved, and battery reliability is markedly enhanced. In addition, compared with Comparative Examples 1-5, the first-cycle discharge capacity and first-cycle coulombic efficiency of the all-solid-state batteries prepared in Examples 1-14 are also significantly improved. See Table 1 for details.

[0573] In Examples 1-14, a dense and flat second carbon layer and a first carbon layer including a porous first carbon material were sequentially deposited on the negative electrode current collector, resulting in very uniform lithium deposition. In Examples 1-14, lithium deposition on the negative electrode current collector was very uniform, and the deposition surface was very flat (the flatness of the deposition surface can be determined by analyzing the longitudinal cross-section at different locations).

[0574] Comparative Example 1 omits the first carbon layer in Example 1 and retains only the second carbon layer including acetylene black, resulting in poor kinetics, reduced initial efficiency, and poor rate performance. The cycle performance (capacity retention after 100 cycles), first-cycle discharge capacity, first coulombic efficiency, and 2C discharge capacity of the prepared solid-state battery all decreased to varying degrees.

[0575] Comparative Example 2 omits the second carbon layer in Example 1, retaining only the first carbon layer including hard carbon. As a result, the uniformity of lithium deposition is significantly worse, the uneven interface leads to obvious uneven lithium deposition, lithium dendrite growth occurs, the battery decays quickly, the coulombic efficiency decreases, and the cycle performance (capacity retention after 100 cycles), first-cycle discharge capacity, first-cycle coulombic efficiency, and 2C discharge capacity of the prepared solid-state battery all decrease to varying degrees.

[0576] Comparative Example 3, by changing the order of the first carbon layer and the second carbon layer in Example 1, showed that the cycle performance (capacity retention after 100 cycles), first-cycle discharge capacity, first coulombic efficiency, and 2C discharge capacity of the prepared solid-state battery decreased to varying degrees.

[0577] In Comparative Example 4, the high pore volume fraction of the second carbon material affected the compactness and smoothness of the second carbon layer, resulting in poorer lithium deposition uniformity compared to Example 1, faster battery degradation, and reduced coulombic efficiency. The cycle performance (capacity retention after 100 cycles), first-cycle discharge capacity, first coulombic efficiency, and 2C discharge capacity of the solid-state battery all decreased to varying degrees.

[0578] In Comparative Example 5, the first carbon material and the second carbon material have the same pore volume fraction. However, the pore volume fraction of the first carbon material is lower than that of the Example 1, while the pore volume fraction of the second carbon material is higher than that of Example 1. This results in poor kinetics and easy growth of lithium dendrites. The cycle performance (capacity retention after 100 cycles), first-cycle discharge capacity, first coulombic efficiency, and 2C discharge capacity of the solid-state battery all decrease to varying degrees.

[0579] Table 1.

[0580] The descriptions of the various implementation methods and embodiments above tend to emphasize the differences between them. Similarities or resemblances can be referenced interchangeably, and for the sake of brevity, they will not be repeated here. The technical features of the implementation methods and embodiments described above can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments have been described. However, as long as the combinations of these technical features do not contradict each other, they should be considered within the scope of this specification.

[0581] It should be noted that this application is not limited to the above-described embodiments and examples. The above-described embodiments and examples are merely examples, and any embodiments and examples that have the same structure and achieve the same effect as the technical concept within the scope of this application are included in the technical scope of this application. The embodiments and examples described above only illustrate several embodiments and examples of this application, and although the descriptions are relatively detailed, they should not be construed as limiting the scope of the patent. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments or examples, and other ways of constructing embodiments or examples by combining some of the constituent elements of the embodiments or examples, are also included in the scope of this application without departing from the spirit of this application.

Claims

A solid-state battery includes a negative electrode current collector, a second carbon layer, a first carbon layer, a solid electrolyte layer and a positive electrode layer stacked sequentially, wherein the second carbon layer includes a second carbon material and the first carbon layer includes a first carbon material. in, The first carbon material is a porous carbon material, and the pore volume fraction of the second carbon material is less than or equal to 5%; at least one of the ion diffusion coefficient and the pore volume fraction of the first carbon material is greater than that of the second carbon material; the D of the second carbon material... v At least one of 50 and average particle size is smaller than the first carbon material; The pore volume fraction of a material refers to the percentage of the total pore volume in the particles relative to the particle volume. According to claim 1, the solid-state battery, wherein, The first carbon material and the second carbon material satisfy one or more of the following characteristics: (a1) The ion diffusion coefficient of the first carbon material is greater than or equal to 1×10⁻⁶ -9 cm 2 / s, optional 1×10 -9 cm 2 / s~5×10 -9 cm 2 / s; (a2) The ion diffusion coefficient of the second carbon material is greater than or equal to 1×10⁻⁶. -10 cm 2 / s, optional 1×10 -10 cm 2 / s~1×10 -9 cm 2 / s. According to claim 2, the solid-state battery, wherein, The first carbon material and the second carbon material satisfy one or more of the following characteristics: (a1') The ion diffusion coefficient of the first carbon material is 2 × 10⁻⁶ -9 cm 2 / s~5×10 -9 cm 2 / s; (a2') The ion diffusion coefficient of the second carbon material is 2 × 10⁻⁶. -10 cm 2 / s~8×10 -10 cm 2 / s. The solid-state battery according to any one of claims 1 to 3, wherein, The first carbon layer and the second carbon layer satisfy one or more of the following characteristics: (b1) The first carbon material includes one or more of hard carbon, soft carbon, artificial graphite and natural graphite; (b2) The second carbon material includes one or more of carbon black, carbon nanotubes, graphene and fullerene; (b3) The second carbon material is a non-porous carbon material; (b4) The second carbon material includes a doping element, which includes one or more of silver, tin, copper, silicon, magnesium and zinc; the doping element is in one or more of the following forms: elemental, carbon alloy and oxide. (b5) The mass percentage of the first carbon material in the first carbon layer is greater than or equal to 90%, and can be selected as 90% to 98%; (b6) The mass percentage of the second carbon material in the second carbon layer is greater than or equal to 90%, and can be selected as 90% to 98%. According to claim 4, the solid-state battery, wherein, The first carbon layer and the second carbon layer satisfy one or more of the following characteristics: (b1') The total mass of hard carbon, soft carbon, artificial graphite and natural graphite accounts for 80% to 100% of the mass of the first carbon material; (b2') The total mass of carbon black, carbon nanotubes, graphene and fullerene accounts for 80% to 100% of the mass of the second carbon material; (b5') The mass percentage of the first carbon material in the first carbon layer is 95% to 98%; (b6') The mass percentage of the second carbon material in the second carbon layer is 95% to 98%. The solid-state battery according to any one of claims 1 to 5, wherein, The first carbon material includes a porous structure, and the first carbon material satisfies one or more of the following characteristics: (c1) The pore volume fraction of the first carbon material is greater than or equal to 25%, optionally 30% to 60%, and further optionally 35% to 55%; (c2) The pore volume of the first carbon material is greater than or equal to 0.1 cm³. 3 / g, can be selected as 0.1cm 3 / g~0.5cm 3 / g; where, the pore volume of the material refers to the ratio of the total pore volume in the particles to the mass of the particles; (c3) The pore structure in the first carbon material includes mesopores and micropores, wherein the diameter of the mesopores is 2m to 50nm and the diameter of the micropores is less than 2nm. The solid-state battery according to claim 5 or 6, wherein, The pore structure of the first carbon material includes mesopores and micropores, and the first carbon material satisfies one or more of the following characteristics: (d1) The mesopores account for 5% to 50% of the total number of pores in the pore structure; (d2) The number of micropores in the pore structure accounts for 10% to 80%. The solid-state battery according to claim 7, wherein, The first carbon material satisfies one or more of the following characteristics: (d1') The mesopores account for 10% to 40% of the total number of pores in the pore structure; (d2') The number of micropores in the pore structure accounts for 10% to 65%. The solid-state battery according to any one of claims 1 to 8, wherein, The first carbon material D v 50 is denoted as D v 501, the first carbon material D v 90 is written as D v 901, the D of the first carbon material v 10 is denoted as D v 101, the SPAN value of the first carbon material is denoted as SPAN1, SPAN1 = (D v 901-D v 101) / D v 501; The first carbon material satisfies one or more of the following characteristics: (e1) D of the first carbon material v 50 or with an average particle size of 50 nm to 2 μm; (e2) The first carbon material satisfies SPAN1 of 1.5 to 4; (e3) The specific surface area of ​​the first carbon material is 50m² 2 / g~500m 2 / g; (e4) The compaction density of the first carbon material powder under a pressure of 5 tons is 0.75 g / cm³. 3 ~0.9g / cm 3 . According to claim 9, the solid-state battery, wherein, The first carbon material satisfies one or more of the following characteristics: (e1') D of the first carbon material v 50 or with an average particle size of 500 nm to 1.5 μm; (e2') The first carbon material satisfies SPAN1 of 1.5 to 2; (e3') The specific surface area of ​​the first carbon material is 300 m² 2 / g~500m 2 / g. The solid-state battery according to any one of claims 1 to 10, wherein, The second carbon material satisfies one or more of the following characteristics: (f1) The average diameter of the primary particles in the second carbon material is 20 nm to 100 nm; (f2) The specific surface area of ​​the second carbon material is 25m². 2 / g~50m 2 / g; (f3) The pore volume fraction of the second carbon material is less than 5%; (f4) The compaction density of the second carbon material powder under a pressure of 5 tons is 0.7 g / cm³. 3 ~0.9g / cm 3 . According to claim 11, the solid-state battery, wherein, The second carbon material satisfies one or more of the following characteristics: (f1) The average diameter of the primary particles in the second carbon material is 20 nm to 80 nm; (f2) The specific surface area of ​​the second carbon material is 40m². 2 / g~50m 2 / g; (f3) The pore volume fraction of the second carbon material is less than 1%. The solid-state battery according to any one of claims 1 to 12, wherein, It meets one or more of the following characteristics: (g1) The thickness of the first carbon layer is 2μm to 8μm; (g2) The thickness of the second carbon layer is 2μm to 8μm; (g3) The thickness ratio of the first carbon layer to the second carbon layer is 5:1 to 1:

5. The solid-state battery according to claim 13 satisfies one or more of the following characteristics: (g1') The thickness of the first carbon layer is 2.5 μm to 7.5 μm; (g2') The thickness of the second carbon layer is 2.5 μm to 7.5 μm; (g3') The thickness ratio of the first carbon layer to the second carbon layer is 3:1 to 1:3; (g4') The sum of the thicknesses of the first carbon layer and the second carbon layer is 5 μm to 15 μm. The solid-state battery according to any one of claims 1 to 14 satisfies one or two of the following characteristics: (h1) The first carbon layer includes a first adhesive; (h2) The second carbon layer includes a second binder. The solid-state battery according to claim 15 satisfies one or two of the following features: (h1') The first carbon layer includes a first adhesive, which includes one or more of polyvinylidene fluoride, polyacrylic acid, styrene-butadiene rubber and carboxymethyl cellulose; (h2') The second carbon layer includes a second adhesive, which includes one or more of polyvinylidene fluoride, polyacrylic acid, styrene-butadiene rubber and carboxymethyl cellulose; (h3') The mass percentage of the first adhesive in the first carbon layer is 2% to 10%; (h4') The second adhesive has a mass percentage content of 2% to 10% in the second carbon layer. The solid-state battery according to any one of claims 1 to 16, wherein, The negative electrode current collector includes one or more of copper, stainless steel, nickel, titanium, aluminum, and alloys composed of at least two of copper, stainless steel, nickel, titanium, and aluminum. The solid-state battery according to any one of claims 1 to 17, wherein, The solid-state battery is a negative electrode-free solid-state battery. The solid-state battery according to any one of claims 1 to 18, wherein, The solid electrolyte layer comprises a solid electrolyte material and a third binder. The solid-state battery according to claim 19 satisfies one or two of the following characteristics: (i1) The mass percentage of the third binder in the solid electrolyte layer is denoted as f. E Satisfying 0 <f E ≤5%; (i2) The third adhesive includes polytetrafluoroethylene, and optionally, the polytetrafluoroethylene accounts for 80% to 100% of the mass of the third adhesive. The solid-state battery according to any one of claims 1 to 20, wherein, The positive electrode layer includes a positive electrode active layer, which includes one or more of lithium transition metal oxide positive electrode materials and lithium phosphate positive electrode materials. The solid-state battery according to any one of claims 1 to 21 satisfies one or two of the following characteristics: (j1) The solid-state battery is a lithium-ion solid-state battery; (j2) The solid-state battery is an all-solid-state battery. A negative electrode sheet includes a negative current collector, a second carbon layer and a first carbon layer stacked sequentially, wherein the second carbon layer includes a second carbon material and the first carbon layer includes a first carbon material. in, The first carbon material is a porous carbon material, and the pore volume fraction of the second carbon material is less than or equal to 5%; at least one of the ion diffusion coefficient and the pore volume fraction of the first carbon material is greater than that of the second carbon material; the D of the second carbon material... v At least one of 50 and average particle size is smaller than the first carbon material; the pore volume fraction of the material refers to the percentage of the total pore volume in the particles relative to the particle volume. The negative electrode sheet according to claim 23 satisfies one or two of the following characteristics: (k1) The negative electrode current collector includes the features of the negative electrode current collector in the solid-state battery according to any one of claims 1 to 22; (k2) The second carbon layer includes the features of the second carbon layer in the solid-state battery according to any one of claims 1 to 22; (k3) The first carbon layer includes the features of the first carbon layer in the solid-state battery according to any one of claims 1 to 22. A method for preparing a solid-state battery includes the following steps: A laminate is prepared by sequentially stacking a positive electrode, a solid electrolyte membrane, and a negative electrode; wherein... The solid electrolyte membrane comprises a solid electrolyte material, and the negative electrode comprises a negative electrode current collector, a second carbon layer, and a first carbon layer stacked sequentially, with the second carbon layer located between the first carbon layer and the solid electrolyte membrane; the second carbon layer comprises a second carbon material, and the first carbon layer comprises a first carbon material; the first carbon material is a porous carbon material; the pore volume fraction of the second carbon material is less than or equal to 5%; at least one of the ion diffusion coefficient and the pore volume fraction of the first carbon material is greater than that of the second carbon material; the D of the second carbon material... v At least one of 50 and average particle size is smaller than the first carbon material; wherein, the pore volume fraction of the material refers to the percentage of the total pore volume in the particles relative to the particle volume; The solid-state battery is prepared by densifying the laminate under heating conditions. The method for preparing a solid-state battery according to claim 25 satisfies one or more of the following characteristics: (m1) The negative electrode sheet is prepared by a method including the following steps: coating a second negative electrode slurry including the second carbon material onto at least one side surface of the negative electrode current collector, drying it, and forming a second carbon layer on at least one side surface of the negative electrode current collector; coating a first negative electrode slurry including the first carbon material onto the second carbon layer, drying it, and forming a first carbon layer on the second carbon layer; (m2) The negative electrode sheet is the negative electrode sheet as described in claim 25; The heating conditions for (m3) are 50℃~100℃; (m4) The pressure for the densification treatment is 300MPa to 600MPa. According to the method for preparing a solid-state battery according to claim 25 or 26, a solid-state battery as described in any one of claims 1 to 22 is prepared. An electrical device comprising at least one of the following: a solid-state battery as described in any one of claims 1 to 22; a negative electrode sheet as described in claim 23 or 24; and a solid-state battery prepared by the method for preparing a solid-state battery as described in claim 25 or 26.

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