Solid-state battery, positive electrode active material, preparation method, positive electrode sheet, and electric device

Abstract

The present application relates to a solid-state battery, a positive electrode active material, a preparation method, a positive electrode sheet, and an electric device. The solid-state battery comprises a positive electrode active layer, wherein the positive electrode active layer comprises a positive electrode active material and a solid electrolyte material. The positive electrode active material comprises a coated oxide-based active material. The coated oxide-based active material comprises a positive electrode active body and a coating layer located on at least part of the surface of the positive electrode active body, wherein the positive electrode active body comprises a lithium transition metal oxide, and the coating layer comprises a lithium metal oxyhalide; and the coating thickness of the coating layer in the coated oxide-based active material is relatively uniform.

Description

Solid-state batteries, positive electrode active materials, preparation methods, positive electrode sheets, and electrical devices.

[0001] Related applications

[0002] This application claims priority to Chinese patent application No. CN2024119971487, filed on December 31, 2024, entitled "Solid-state battery, positive electrode active material, preparation method, positive electrode sheet and electrical device", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of solid-state battery technology, and further to solid-state batteries, positive electrode active materials, preparation methods, positive electrode sheets, and electrical devices, and even further to solid-state batteries, positive electrode active materials, preparation methods of coated oxide active materials, positive electrode sheets, and electrical devices. 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 use a non-flammable solid electrolyte instead of the organic electrolyte in traditional liquid secondary batteries, significantly improving battery safety and are considered the next generation of batteries closest to industrialization. However, interface compatibility issues in solid-state batteries lead to less than ideal cycle performance. Summary of the Invention

[0006] According to various embodiments and examples of this application, this application provides a solid-state battery, a positive electrode active material, a preparation method, a positive electrode sheet, and an electrical device, and further provides a solid-state battery, a positive electrode active material, a preparation method for a coated oxide-based active material, a positive electrode sheet, and an electrical device. This solid-state battery exhibits significantly improved cycle performance.

[0007] In a first aspect of this application, a solid-state battery is provided, comprising a positive electrode active layer, the positive electrode active layer comprising a positive electrode active material and a solid electrolyte material; the positive electrode active material comprises a coated oxide active material, the coated oxide active material comprising a positive electrode active body and a coating layer located on at least a portion of the surface of the positive electrode active body, the positive electrode active body comprising a lithium transition metal oxide, and the coating layer comprising a lithium metal halide oxide; the coating thickness of the coating layer in the coated oxide active material is relatively uniform.

[0008] In some embodiments, a solid-state battery is provided, comprising a positive electrode layer, a solid electrolyte layer, and a negative electrode layer stacked sequentially, wherein the positive electrode layer includes a positive electrode active layer, the positive electrode active layer comprising a positive electrode active material and a solid electrolyte material; the positive electrode active material includes a coated oxide active material, the coated oxide active material comprising a positive electrode active body and a coating layer located on at least a portion of the surface of the positive electrode active body, the positive electrode active body comprising a lithium transition metal oxide, and the coating layer comprising a lithium metal halide oxide;

[0009] The difference between the maximum and minimum thickness of the coating layer in the coated oxide active material is denoted as ΔD, the average thickness of the coating layer in the coated oxide active material is denoted as D1, and the ratio of ΔD to D1 is denoted as R1.

[0010] The coated oxide-based active material satisfies one or two of the following characteristics:

[0011] (v1)ΔD≤50nm;

[0012] (v2)R1≤0.5.

[0013] In the coated oxide active material set in the positive electrode active layer, the coating layer has a relatively uniform thickness and contains lithium metal halide oxide with high ionic conductivity. This can significantly reduce the positive electrode interface impedance, significantly reduce the positive electrode interface polarization caused by coating layer thickness fluctuations, effectively improve the solid-phase transport of positive electrode active ions, greatly promote the positive electrode capacity, and significantly improve the cycle performance of solid-state batteries.

[0014] Unless otherwise stated, the improvements described in this application are not intended to be limited to any theoretical constraints.

[0015] By introducing coated oxide-based active materials with high ionic conductivity and good coating uniformity, the interface impedance of the positive electrode can be significantly reduced, which can facilitate the more efficient insertion of active ions into the positive electrode during the first charge and discharge process, thereby significantly improving the coulombic efficiency of solid-state batteries.

[0016] The percentage of the coverage area of ​​the coating layer relative to the positive electrode active body in the coated oxide active material is denoted as F. A .

[0017] In some embodiments, the coated oxide-based active material satisfies one or more of the following characteristics:

[0018] (a1) ΔD ≤ 30nm;

[0019] (a2) R1 is 0 to 0.3;

[0020] (a3)F A ≥80%.

[0021] In some embodiments, the coated oxide-based active material satisfies one or more of the following characteristics:

[0022] (a1')ΔD≤15nm;

[0023] (a2')R1 is 0 to 0.25;

[0024] (a3')F A It ranges from 80% to 100%.

[0025] In some embodiments, the coated oxide-based active material satisfies one or more of the following characteristics:

[0026] (a1”)ΔD≤10nm;

[0027] (a2')R1 is 0 to 0.2;

[0028] (a3”)F A It is 95% to 100%.

[0029] By controlling ΔD and / or R1 to a lower range, coated oxide-based active materials with more uniform coating thickness can be provided. This helps to better reduce the polarization of the cathode interface caused by coating thickness fluctuations, and thus improves the cycle performance of solid-state batteries. Furthermore, it also helps to improve the initial coulombic efficiency of solid-state batteries.

[0030] By using the difference between the maximum and minimum thicknesses of the coating layer in the coated oxide active material ΔD, the ratio of the difference between the maximum and minimum thicknesses of the coating layer ΔD to the average thickness D1 R1 (R1 = ΔD / D1), and the percentage of the coating layer's coverage area relative to the positive electrode active body in the coated oxide active material (F... A Controlling one or more parameters within the aforementioned range is beneficial for improving the uniformity of the coating layer on the surface of the coated oxide-based active material, and for improving the cycle performance of the solid-state battery. Furthermore, it also helps to improve the initial coulombic efficiency of the solid-state battery.

[0031] The average thickness of the coating layer in the coated oxide active material is denoted as D1.

[0032] In some embodiments, the coated oxide-based active material satisfies one or more of the following characteristics:

[0033] (b1)D1 is 10nm to 100nm, and can be selected as 20nm to 80nm;

[0034] (b2) The thickness of at least a portion of the coating layer is greater than or equal to 10 nm, optionally 10 nm to 100 nm, further optionally 10 nm to 80 nm, and even more preferably 10 nm to 60 nm;

[0035] (b3) In the coated oxide active material, the lithium metal halide oxide accounts for 70% to 100% by mass in the coating layer, optionally 80% to 100%, and further optionally 90% to 100%;

[0036] (b4) The lithium metal halide oxide accounts for 0.2% to 2% of the mass of the coated oxide active material, and may be 0.5% to 2%.

[0037] In some embodiments, the coated oxide-based active material satisfies one or more of the following characteristics:

[0038] (b1')D1 is 20nm~60nm;

[0039] (b2') At least a portion of the coating layer has a thickness of 20 nm to 50 nm;

[0040] (b3') In the coated oxide active material, the lithium metal halide oxide accounts for 90% to 100% of the mass of the coating layer;

[0041] (b4') The lithium metal halide oxide accounts for 0.5% to 2% of the mass of the coated oxide active material.

[0042] By measuring the average thickness (D1) of the coating layer in the coated oxide active material, the thickness of at least a portion of the coating layer, and the mass percentage (F) of lithium metal halide oxide in the coating layer, the method can be used to determine the composition of the coating layer. X1 ) and lithium metal halide oxides in coated oxide active materials (F X0 Controlling one or more parameters in the mass ratio of the material within the aforementioned range is beneficial for controlling the coating amount on the surface of the coated oxide active material to be more suitable. This not only significantly reduces the interface impedance of the positive electrode, but also helps to take into account the energy density of the positive electrode.

[0043] In some embodiments, the lithium metal halide oxide includes lithium, non-lithium metal elements, halogens, and oxygen; the halide formed by the non-lithium metal elements and halogens in the lithium metal halide oxide is denoted as M halide, and the M halide satisfies one or more of the following characteristics:

[0044] (c1) The M halide is in a gaseous or liquid state at 120℃~400℃, and may be in a gaseous state;

[0045] (c2) The melting point of the M halide is 120℃~400℃;

[0046] (c3) The boiling point of the M halide is 120℃~400℃.

[0047] In some embodiments, the M halide satisfies one or more of the following characteristics:

[0048] (c1') The M halide is in a gaseous or liquid state at 150°C to 350°C, and may be in a gaseous state; optionally, the M halide is in a liquid or gaseous state at 180°C to 300°C, and may be further selected as a gaseous state;

[0049] (c2') The melting point of the M halide is 150℃~350℃, and can be selected as 180℃~300℃;

[0050] (c3') The boiling point of the M halide is 150℃~350℃, and can be selected as 180℃~300℃.

[0051] By selecting lithium metal halide oxides in the coating layer that include the aforementioned types, in-situ coating reactions can be carried out using gaseous and / or liquid M halides and residual alkali on the surface of lithium transition metal oxides at relatively low temperatures (e.g., 120℃~400℃) far below the sintering temperature of the positive electrode active material. This allows for the formation of lithium metal halide oxides with high ionic conductivity while also controlling the coating layer to have a relatively uniform thickness distribution.

[0052] In some embodiments, the lithium metal halide oxide includes lithium, non-lithium metal elements, halogens, and oxygen; wherein the non-lithium metal elements include one or more of Zr, Ta, Nb, In, W, Ge, Ga, Sb, Sn, Al, and Ti.

[0053] In some embodiments, the halogen in the lithium metal halide includes one or more of F, Cl, Br and I.

[0054] In some embodiments, the halogen in the lithium metal halide oxide includes one or both of F and Cl.

[0055] The aforementioned halides of non-lithium metal elements all have relatively low melting and / or boiling points (e.g., 120°C to 400°C). At relatively low temperatures, these halides of non-lithium metal elements can be controlled to undergo in-situ coating reactions with the surface residual alkali of lithium transition metal oxides in gaseous and / or liquid states, thereby forming coating layers with high ionic conductivity and uniform coating thickness.

[0056] In some embodiments, the atomic molar ratio of halogen to oxygen in the lithium metal halide is (1-4):(0.8-1.2).

[0057] In some embodiments, the atomic molar ratio of halogen to oxygen in the lithium metal halide oxide is (2-5):1.

[0058] By controlling the atomic molar ratio of halogens and oxygen in lithium metal halide oxides within the aforementioned range, it is beneficial to balance the high ionic conductivity of the coating, the chemical stability of the coating, and its sensitivity to water.

[0059] In some embodiments, the lithium metal halide oxide has the chemical formula Li. a M b O c X d The M element in the lithium metal halide oxide includes one or more of Zr, Ta, Nb, In, W, Ge, Ga, Sb, Sn, Al, and Ti; a is 1 to 2, b is 0.8 to 1.2, c is 0.8 to 1.2, d is 1 to 4, and X is a halogen.

[0060] In some embodiments, the X element in the lithium metal halide oxide is selected from one or both of F and Cl.

[0061] In some embodiments, the D of the positive electrode active material v 50 is 2μm to 10μm, and can be selected from 3μm to 6μm, where D v 50 represents the particle size at which the cumulative volume distribution percentage of the multi-particle mixture reaches 50%.

[0062] By using the D of the positive electrode active material v Controlling the 50 within the aforementioned range is beneficial for forming a uniform coating, achieving better intrinsic interface contact, and better balancing the reduction of positive electrode interface impedance and positive electrode energy density.

[0063] The relatively small particle size of the positive electrode active material is beneficial to further improve the interfacial contact of the positive electrode and to better reduce the interfacial impedance of the positive electrode.

[0064] In some embodiments, the lithium transition metal oxide includes one or more of lithium nickel-based oxides, lithium-rich manganese-based cathode active materials, spinel lithium manganese oxide, and lithium cobalt oxide.

[0065] In some embodiments, the lithium transition metal oxide includes a lithium nickel-based oxide; wherein the lithium nickel-based oxide includes Li, a non-lithium metal element, and O, and the non-lithium metal element includes Ni.

[0066] The lithium transition metal oxide satisfies one or more of the following characteristics:

[0067] (i1) The atomic molar ratio of Ni to the non-lithium metal element in the lithium nickel-based oxide is q1, where 0.5 ≤ q1 ≤ 1;

[0068] (i2) The lithium nickel-based oxide contains Ni and Li elements in an atomic molar ratio of q2:x2, wherein 0.5≤q2≤1 and 0.6≤x2≤1.2;

[0069] (i3) The lithium nickel-based oxide contains Ni and O elements in an atomic molar ratio of q3:x3, wherein 0.5≤q3≤1 and 1.6≤x3≤2.2;

[0070] (i4) The lithium nickel-based oxide contains Co;

[0071] (i5) The lithium nickel-based oxide contains the element Mn;

[0072] (i6) The lithium nickel-based oxide has a layered crystal structure.

[0073] In some embodiments, the lithium transition metal oxide satisfies one or more of the following characteristics:

[0074] (t1)0.6≤q1≤1; optionally, 0.6≤q1≤0.96;

[0075] (t2)0.6≤q2≤1; optionally, 0.6≤q2≤0.96;

[0076] (t3)0.6≤x2≤1.1;

[0077] (t4)0.6≤q3≤1; optionally, 0.6≤q3≤0.96;

[0078] (t5)1.8≤x3≤2.1;

[0079] (t6) The lithium nickel-based oxide contains Co, and the atomic molar ratio of Co to non-lithium metal elements in the lithium nickel-based oxide is q4, wherein 0.02≤q4≤0.35;

[0080] (t7) The lithium nickel-based oxide contains Mn element, and the atomic molar ratio of Mn element to non-lithium metal element in the lithium nickel-based oxide is q5, wherein 0.01≤q5≤0.38;

[0081] (t8) The lithium nickel-based oxide accounts for 80% to 100% of the mass of the lithium transition metal oxide.

[0082] In some embodiments, the lithium transition metal oxide satisfies one or more of the following characteristics:

[0083] (t1')0.5≤q1≤0.99; optionally, 0.5≤q1≤0.9;

[0084] (t2')0.5≤q2≤0.99; optionally, 0.5≤q2≤0.9;

[0085] (t3')0.8≤x2≤1.1;

[0086] (t4')0.5≤q3≤0.99; optionally, 0.5≤q3≤0.9;

[0087] (t5')1.8≤x3≤2.06;

[0088] (t6') The lithium nickel-based oxide contains Co, with 0.05 ≤ q4 ≤ 0.25;

[0089] (t7') The lithium nickel-based oxide contains Mn element, 0.05≤q5≤0.3;

[0090] (t8') The lithium nickel-based oxide accounts for 90% to 100% of the mass of the lithium transition metal oxide;

[0091] (t9') The lithium transition metal oxide includes lithium nickel cobalt manganese-based oxide, and optionally, the lithium nickel cobalt manganese-based oxide accounts for 80% to 100% of the mass of the lithium transition metal oxide, and more preferably 90% to 100%;

[0092] (t10') The lithium transition metal oxide includes lithium nickel cobalt manganese-based oxides; in the lithium nickel cobalt manganese-based oxides, the ratio of the sum of the atomic molar ratios of nickel, cobalt, and manganese to the sum of the atomic molar ratios of non-lithium metal elements is denoted as R. NCM R NCM The value is 0.9 to 1; optionally, R NCM It ranges from 0.95 to 1.

[0093] By incorporating the aforementioned types of lithium transition metal oxides into coated oxide-based active materials, it is beneficial to improve the energy density of solid-state batteries. When the lithium transition metal oxide includes lithium nickel-based oxides, controlling the nickel content within the aforementioned range is beneficial to improving the structural stability of the cathode active material at high voltages (e.g., 4.0V–4.8V, further such as 4.0V–4.5V). Furthermore, lithium-rich manganese-based cathode active materials, spinel lithium manganese oxide, and lithium cobalt oxide also exhibit good structural stability at high voltages.

[0094] In some embodiments, the positive electrode active material satisfies one or more of the following characteristics:

[0095] (e1) The lithium metal halide oxide has an ionic conductivity of 1 mS / cm to 10 mS / cm at 25 °C.

[0096] (e2) The ionic conductivity of the positive electrode active material at 25℃ is greater than or equal to 0.01 mS / cm;

[0097] (e3) The positive electrode active material or the coated oxide active material has an ionic conductivity at 25°C greater than or equal to 0.01 mS / cm.

[0098] In some embodiments, the solid electrolyte material includes a sulfide solid electrolyte.

[0099] For solid-state batteries with cathode active materials including coated oxide active materials and solid electrolyte materials including sulfide solid electrolytes, on the one hand, the introduction of coated oxide active materials helps reduce cathode interfacial impedance and polarization, significantly improving the cycle performance of solid-state batteries. On the other hand, sulfide solid electrolytes have excellent high ionic conductivity, and the coating layer in the coated oxide active material can effectively reduce the direct contact between the lithium transition metal oxide inside the coated oxide active material and the sulfide solid electrolyte, which helps to significantly suppress the decomposition effect of oxygen released from the lithium transition metal oxide lattice on the sulfide solid electrolyte. This significantly improves the interfacial stability between the cathode active material and the solid electrolyte material, and significantly enhances the structural stability and ion conduction stability of the solid electrolyte material. Based on the aforementioned multiple effects, it is beneficial to better improve the cycle performance of solid-state batteries. In addition, a higher initial coulombic efficiency can also be achieved.

[0100] 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.

[0101] In some embodiments, the sulfide solid electrolyte satisfies one or more of the following characteristics:

[0102] (f1) The sulfide electrolyte of the silver-germanium sulfide type includes 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 1 Selected from one or more elements of Ge, Si, Sn, and Sb, B 1X is selected from one or more elements of O, Se, and Te. 1 One or more elements selected from Cl, Br, I, and F;

[0103] (f2) The LGPS-type sulfide electrolyte includes 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 One or more elements selected from O, Se, Te, Cl, Br, I, and F;

[0104] (f3) The lithium sulfide pentaphosphine complex sulfide electrolyte comprises 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 One or more elements selected from Li, B, Ge, Si, Sn, and Sb, N 3 One or more elements selected from S, Se, Te, O, Cl, Br, I, and F.

[0105] In some embodiments, the positive electrode active layer satisfies one or more of the following characteristics:

[0106] (d1) The mass percentage of the coated oxide active material in the positive electrode active material is 80% to 100%;

[0107] (d2) The mass percentage of the coated oxide active material in the positive electrode active layer is 70% to 98%;

[0108] (d3) The solid electrolyte material in the positive electrode active layer has a mass percentage content of 2% to 30%;

[0109] (d4) The solid electrolyte material includes a sulfide solid electrolyte; the sulfide solid electrolyte has a mass percentage content of 2% to 30% in the positive electrode active layer.

[0110] In some embodiments, the positive electrode active layer satisfies one or more of the following characteristics:

[0111] (d1') The mass percentage of the coated oxide active material in the positive electrode active material is 90% to 100%;

[0112] (d2') The mass percentage of the coated oxide active material in the positive electrode active layer is 75% to 95%;

[0113] (d3') The solid electrolyte material in the positive electrode active layer has a mass percentage content of 5% to 25%;

[0114] (d4') The solid electrolyte material includes a sulfide solid electrolyte; the sulfide solid electrolyte has a mass percentage content of 5% to 25% in the positive electrode active layer.

[0115] By measuring the mass ratio (F) of coated oxide active materials in the positive electrode active material M1 ), the mass percentage of coated oxide active materials in the positive electrode active layer (F) M0 Controlling one or two parameters within the aforementioned range is more conducive to reducing the positive electrode interface impedance and improving the cycle performance of solid-state batteries through coated oxide active materials.

[0116] By measuring the mass ratio (F) of coated oxide active materials in the positive electrode active material M1 ), the mass percentage of coated oxide active materials in the positive electrode active layer (F) M0 Controlling one or more parameters, such as the mass percentage of solid electrolyte material in the positive electrode active layer and the mass percentage of sulfide solid electrolyte in the positive electrode active layer, within the aforementioned range is beneficial to better promote the synergistic effect of coated oxide active materials and solid electrolyte materials (such as sulfide solid electrolyte) in the positive electrode active layer to improve the cycle performance of solid-state batteries.

[0117] In some embodiments, the solid electrolyte material includes a sulfide solid electrolyte, wherein the sulfide solid electrolyte has a mass percentage of 5% to 12% in the positive electrode active layer, and is optionally 5% to 10%.

[0118] Optionally, the solid electrolyte material has a mass percentage content of 5% to 12% in the positive electrode active layer, and can be optionally 5% to 10%.

[0119] By introducing coated oxide-based active materials, the amount of solid electrolyte material (such as sulfide solid electrolyte) used in the positive electrode active layer can be reduced while maintaining good specific capacity of the positive electrode, thereby improving the energy density of solid-state batteries.

[0120] In some embodiments, the solid-state battery is an all-solid-state battery.

[0121] In some embodiments, the solid-state battery is a lithium-ion secondary battery, which may be an all-solid-state lithium-ion secondary battery.

[0122] In some embodiments, the charging cutoff voltage of the solid-state battery is 3.8V to 4.8V, and can be selected as 4.0V to 4.5V.

[0123] In a second aspect of this application, a positive electrode active material is provided, comprising a coated oxide active material, wherein the coated oxide active material comprises a positive electrode active body and a coating layer located on at least a portion of the surface of the positive electrode active body, the positive electrode active body comprising a lithium transition metal oxide, and the coating layer comprising a lithium metal halide oxide.

[0124] The average thickness of the coating layer in the coated oxide active material is denoted as D1, and the ratio of ΔD to D1 is denoted as R1; the coated oxide active material satisfies one or both of the following characteristics: (v1) ΔD≤50nm; (v2) R1≤0.5.

[0125] For positive electrode active materials including coated oxide active materials, as mentioned above, the coating layer in coated oxide active materials has a relatively uniform thickness, and lithium metal halide oxide with high ionic conductivity is set in the coating layer. This can significantly reduce the positive electrode interface impedance, significantly reduce the positive electrode interface polarization caused by the coating layer thickness fluctuation, effectively improve the solid phase transport of positive electrode active ions, greatly promote the positive electrode capacity, and significantly improve the cycle performance of solid-state batteries.

[0126] By introducing coated oxide-type active materials with high ionic conductivity and good coating uniformity into the positive electrode active material, the interface impedance of the positive electrode can be significantly reduced, which can significantly improve the coulombic efficiency of solid-state batteries.

[0127] In some embodiments, the positive electrode active material includes the characteristics of the positive electrode active material in a solid-state battery as described in the first aspect of this application.

[0128] In some embodiments, the lithium transition metal oxide includes lithium nickel-based oxides;

[0129] The lithium transition metal oxide satisfies one or more of the following characteristics:

[0130] (j1) The atomic molar ratio of Ni element to non-lithium metal element in the lithium nickel-based oxide is q1, where 0.5≤q1≤1;

[0131] (j2) The lithium nickel-based oxide contains Ni and Li elements in an atomic molar ratio of q2:x2, wherein 0.5≤q2≤1 and 0.9≤x2≤1.1;

[0132] (j3) The lithium nickel-based oxide contains Ni and O elements in an atomic molar ratio of q3:x3, wherein 0.5≤q3≤1 and 1.8≤x3≤2.1;

[0133] (j4) The lithium nickel-based oxide contains Co.

[0134] (j5) The lithium nickel-based oxide contains the element Mn;

[0135] (j6) The lithium nickel-based oxide has a layered crystal structure.

[0136] In some embodiments, the lithium transition metal oxide satisfies one or more of the following characteristics:

[0137] (z1)0.6≤q1≤1; optionally, 0.6≤q1≤0.96;

[0138] (z2)0.6≤q2≤1; optionally, 0.6≤q2≤0.96;

[0139] (z3)0.98≤x2≤1.02;

[0140] (z4)0.6≤q3≤1; optionally, 0.6≤q3≤0.96;

[0141] (z5)1.96≤x3≤2.04;

[0142] (z6) The lithium nickel-based oxide contains Co, and the atomic molar ratio of Co to non-lithium metal elements in the lithium nickel-based oxide is q4, wherein 0.02≤q4≤0.35;

[0143] (z7) The lithium nickel-based oxide contains Mn element, and the atomic molar ratio of Mn element to non-lithium metal element in the lithium nickel-based oxide is q5, wherein 0.01≤q5≤0.38;

[0144] (z8) The lithium nickel-based oxide accounts for 80% to 100% of the mass of the lithium transition metal oxide.

[0145] In some embodiments, the lithium transition metal oxide satisfies one or more of the following characteristics:

[0146] (z1')0.5≤q1≤0.99; optionally, 0.5≤q1≤0.8;

[0147] (z2')0.5≤q2≤0.99; optionally, 0.5≤q2≤0.8;

[0148] (z3')0.99≤x2≤1.01;

[0149] (z4')0.5≤q3≤0.99; optionally, 0.5≤q3≤0.8;

[0150] (z5')1.98≤x3≤2.02;

[0151] (z6') The lithium nickel-based oxide contains Co element, 0.05≤q4≤0.25;

[0152] (z7') The lithium nickel-based oxide contains Mn element, 0.02≤q5≤0.38;

[0153] (z8') The lithium nickel-based oxide accounts for 90% to 100% of the mass of the lithium transition metal oxide;

[0154] (z9') The lithium transition metal oxides include lithium nickel cobalt manganese-based oxides.

[0155] In some embodiments, the positive electrode active material satisfies one or more of the following characteristics:

[0156] (g1) The lithium transition metal oxide includes lithium nickel cobalt manganese-based oxides; in the lithium nickel cobalt manganese-based oxides, the ratio of the sum of the atomic molar ratios of nickel, cobalt, and manganese to the sum of the atomic molar ratios of non-lithium metal elements is denoted as R. NCM R NCM The value is 0.9 to 1; optionally, R NCM It ranges from 0.95 to 1;

[0157] (g2) The mass percentage of the coated oxide active material in the positive electrode active material is 80% to 100%, and can be 90% to 100%;

[0158] (g3) The lithium metal halide oxide has an ionic conductivity at 25°C greater than or equal to 1 mS / cm, and can be selected as 1 mS / cm to 10 mS / cm.

[0159] (g4) The ionic conductivity of the positive electrode active material at 25℃ is greater than or equal to 0.01 mS / cm;

[0160] (g5) The ionic conductivity of the coated oxide active material at 25°C is greater than or equal to 0.01 mS / cm.

[0161] In a third aspect of this application, a method for preparing a coated oxide-based active material is provided, comprising the following steps:

[0162] An oxide-based positive electrode active material is provided; wherein the oxide-based positive electrode active material includes a positive electrode active body and a lithium-containing residual alkali located on at least a portion of the surface of the positive electrode active body, and the positive electrode active body includes a lithium transition metal oxide;

[0163] Under selected atmosphere and heating conditions, the oxide-based positive electrode active material is subjected to an in-situ coating reaction with a non-solid metal halide, so that the lithium-containing residual alkali reacts with the non-solid metal halide to form lithium metal halide oxide. After cooling, a coated oxide-based active material is obtained; wherein, the selected atmosphere is a vacuum condition or an inert gas atmosphere, and the metal element in the non-solid metal halide is a non-lithium metal element.

[0164] Wherein, the average thickness of the coating layer in the coated oxide active material is denoted as D1, and the ratio of ΔD to D1 is denoted as R1; the coated oxide active material satisfies one or both of the following characteristics: (v1) ΔD≤50nm; (v2) R1≤0.5.

[0165] By in-situ coating a non-solid metal halide with an oxide-based positive electrode active material containing lithium residual alkali, a lithium metal halide oxide with high ionic conductivity can be formed while maintaining a relatively uniform thickness distribution of the coating layer. Furthermore, the in-situ coating reaction consumes a significant amount of the residual alkali on the surface of the oxide-based positive electrode active material, further reducing the interfacial impedance of the positive electrode active material. Applying the prepared coated oxide-based active material to positive electrode sheets and solid-state batteries can significantly reduce the positive electrode interfacial impedance, significantly reduce positive electrode interfacial polarization caused by coating layer thickness fluctuations, effectively improve the solid-phase transport of positive electrode active ions, greatly promote positive electrode capacity utilization, and significantly improve the cycle performance of solid-state batteries. Moreover, the method is simple, highly controllable, easy to operate, and low in cost, making it suitable for large-scale production.

[0166] Compared to the method of physically mixing oxide-based active materials with prepared metal halide oxides to achieve coating, the aforementioned in-situ coating reaction method produces a coating layer with better uniformity and a more uniform coating thickness.

[0167] In addition, coated oxide active materials have high ionic conductivity and good coating uniformity. By introducing such coated oxide active materials into the cathode layer, the cathode interface impedance can be significantly reduced, and the coulombic efficiency of solid-state batteries can be significantly improved.

[0168] In some embodiments, the preparation method of the coated oxide-based active material satisfies one or more of the following characteristics:

[0169] (h1) The non-solid metal halide is one or both of gaseous and liquid states;

[0170] (h2) The melting point of the non-solid metal halide is 120℃~400℃, optionally 150℃~350℃, and further optionally 180℃~300℃;

[0171] (h3) The boiling point of the non-solid metal halide is 120℃~400℃, optionally 150℃~350℃, and further optionally 180℃~300℃;

[0172] (h4) The temperature for carrying out the in-situ coating reaction is 120℃~400℃, optionally 150℃~350℃, and further optionally 180℃~300℃; optionally, the reaction time is 2h~6h;

[0173] (h5) The metal element in the non-solid metal halide includes one or more of Zr, Ta, Nb, In, W, Ge, Ga, Sb, Sn, Al and Ti;

[0174] (h6) The halogen in the non-solid metal halide includes one or more of F, Cl, Br and I.

[0175] In some embodiments, the preparation method of the coated oxide-based active material satisfies one or more of the following characteristics:

[0176] (k1) The non-solid metal halide is in a gaseous state;

[0177] (k2) The lithium transition metal oxide includes one or more of lithium nickel-based oxides, lithium-rich manganese-based positive electrode active materials, spinel lithium manganese oxide, and lithium cobalt oxide;

[0178] (k3) The lithium-containing residual alkali includes one or more of lithium carbonate and lithium hydroxide;

[0179] (k4) In the oxide-based positive electrode active material, the mass percentage of the lithium-containing residual alkali is 0.5% to 2%;

[0180] (k5) The initial ratio of the oxide-based positive electrode active material to the non-solid metal halide salt is (30-50):1, based on the amount of material fed.

[0181] (k6) Based on the amount of material fed, the atomic molar ratio of halogen in the non-solid metal halide to oxygen in the oxide-type positive electrode active material is (1-4):(0.8-1.2), which can be selected as 1-5, and further selected as 2-5;

[0182] (k7) The lithium metal halide oxide has an ionic conductivity of 1 mS / cm to 10 mS / cm at 25 °C.

[0183] (k8) The ionic conductivity of the coated oxide active material prepared at 25℃ is greater than or equal to 0.01 mS / cm;

[0184] (k9) The coated oxide active material obtained includes the characteristics of the coated oxide active material in the positive electrode active material described in the second aspect of this application.

[0185] By selecting the aforementioned types of non-solid metal halide salts, in-situ coating reactions can be carried out between gaseous and / or liquid M halides and the surface residual alkali of lithium transition metal oxides at relatively low temperatures (such as 120℃~400℃), far below the sintering temperature of the positive electrode active material, thereby forming a coating layer with high ionic conductivity and relatively uniform coating thickness.

[0186] In a fourth aspect of this application, a positive electrode sheet is provided, comprising a positive electrode active layer, wherein the positive electrode active layer comprises at least one of the positive electrode active material described in the second aspect of this application and a coated oxide active material prepared by the preparation method of the coated oxide active material described in the third aspect of this application, or the positive electrode active layer comprises the characteristics of the positive electrode active layer in the solid-state battery described in the first aspect of this application.

[0187] In a fifth aspect of this application, an electrical device is provided, comprising at least one of the following: a solid-state battery as described in the first aspect of this application, a positive electrode active material as described in the second aspect of this application, a coated oxide active material prepared by the method for preparing coated oxide active materials as described in the third aspect of this application, and a positive electrode sheet as described in the fourth aspect of this application.

[0188] 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

[0189] 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:

[0190] Figure 1 is a schematic diagram of a solid-state battery cell according to an embodiment of this application.

[0191] Figure 2 is an exploded view of a solid-state battery cell according to an embodiment of this application shown in Figure 1.

[0192] Figure 3 is a schematic diagram of a battery device according to an embodiment of this application.

[0193] Figure 4 is a schematic diagram of a battery pack according to one embodiment of this application.

[0194] Figure 5 is an exploded view of the battery pack of one embodiment of this application shown in Figure 4.

[0195] Figure 6 is a schematic diagram of an electrical device using a solid-state battery as a power source according to an embodiment of this application.

[0196] Figure 7 shows the first charge-discharge curve of a solid-state battery according to an embodiment of this application.

[0197] Figure 8 shows a transmission electron microscope (TEM) image and TEM-EDS selected area test results of the coated oxide active material in one embodiment of this application. The right figure shows the distribution of Cl element.

[0198] Figure 9 shows a transmission electron microscope (TEM) image and TEM-EDS selected area test results of the coated oxide active material in one embodiment of this application. The right figure shows the distribution of Cl element.

[0199] Figure 10 is a transmission electron microscope (TEM) image of the coated oxide-based active material according to one embodiment of this application. The left and right images correspond to different magnifications.

[0200] Figure 11 is a transmission electron microscope (TEM) image of a coated oxide-based active material according to an embodiment of this application.

[0201] Explanation of reference numerals in the attached figures:

[0202] 1. Battery pack; 2. Upper casing; 3. Lower casing; 4. Battery assembly; 5. Solid-state battery cell; 51. Housing; 52. Solid-state battery cell; 53. Cover plate; 6. Electrical device. Detailed Implementation

[0203] The following describes in detail, with appropriate reference to the accompanying drawings, some embodiments of the solid-state battery, positive electrode active material, preparation method, positive electrode sheet, and electrical device of this application. However, some unnecessary details 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 for the purpose of providing a full understanding of this application by those skilled in the art and are not intended to limit the subject matter of the claims.

[0204] 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.

[0205] 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.

[0206] 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".

[0207] 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.

[0208] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0209] 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.

[0210] 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.

[0211] 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."

[0212] 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.

[0213] 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."

[0214] 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.

[0215] 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.

[0216] 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.

[0217] 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.

[0218] 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.

[0219] In this application, the terms "first aspect," "second aspect," "third aspect," "fourth aspect," and "fifth 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," and "fifth" etc. serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on quantity.

[0220] 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.

[0221] 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℃.

[0222] 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.

[0223] 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.

[0224] Unless otherwise stated, the improvements described in this application are not intended to be limited to any theoretical constraints.

[0225] 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.

[0226] Interfacial contact issues in solid-state batteries have always been a key problem restricting the improvement of solid-state battery performance (including cycle performance). During charge-discharge cycles, reversible extraction and insertion of active ions occur at the positive electrode, leading to volume changes in the positive electrode active material. This affects the stability of the solid-phase interfacial contact within the positive electrode layer, potentially causing poorer contact between the active materials and increasing the positive electrode interfacial impedance, thus impacting the cycle performance of the solid-state battery. Furthermore, poor solid-phase interfacial contact within the positive electrode layer also affects the initial coulombic efficiency.

[0227] By coating and modifying the surface of the positive electrode active material, its volume change during charge-discharge cycling can be suppressed. However, in existing coating methods, the ionic conductivity of the coating layer remains low in some methods, resulting in limited improvement in the transport kinetics of active ions; some methods improve the solid-phase interface contact of the positive electrode by increasing the amount of solid electrolyte material, however, this reduces the loading of the positive electrode active material and the specific capacity of the positive electrode.

[0228] According to various embodiments and examples of this application, this application provides a solid-state battery, a positive electrode active material, a preparation method, a positive electrode sheet, and an electrical device. This solid-state battery exhibits significantly improved cycle performance.

[0229] In some embodiments, a solid-state battery is provided, comprising a positive electrode layer, which includes a positive electrode active layer, a positive electrode active material, and a solid electrolyte material. The positive electrode active material includes a coated oxide-based active material, comprising a positive electrode active body and a coating layer located on at least a portion of the surface of the positive electrode active body. The coating layer includes lithium metal halide oxide. The coating thickness of the coating layer in the coated oxide-based active material is relatively uniform. This solid-state battery exhibits significantly improved cycle performance.

[0230] In some implementations, the positive electrode active body comprises a lithium transition metal oxide.

[0231] In some embodiments, the solid-state battery includes a positive electrode layer, which includes a positive electrode active layer, and the positive electrode active layer includes a positive electrode active material and a solid electrolyte material; the positive electrode active material includes a coated oxide active material, which includes a positive electrode active body and a coating layer located on at least a portion of the surface of the positive electrode active body, the positive electrode active body including a lithium transition metal oxide, and the coating layer including a lithium metal halide oxide; the coating thickness of the coating layer in the coated oxide active material is relatively uniform.

[0232] In some embodiments, a solid-state battery includes a positive electrode layer, a solid electrolyte layer, and a negative electrode layer stacked sequentially.

[0233] 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 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.

[0234] Unless otherwise specified, the term "solid-state battery" in this application refers to a battery in which the electrolyte includes a solid electrolyte material. Typically, a solid-state battery includes a positive electrode layer, a solid electrolyte layer, and a negative electrode layer. During charging and discharging, active ions repeatedly insert and extract between the positive and negative electrode layers. The solid electrolyte layer acts as a conductor of ions between the positive and negative electrode layers and also isolates them, preventing short circuits. Therefore, a separator, as found in traditional lithium-ion batteries, is not required in solid-state batteries. Solid-state batteries use a non-flammable solid electrolyte instead of the organic electrolyte in traditional liquid lithium-ion batteries, significantly improving battery safety. In addition to enhanced safety, solid-state batteries are better suited for high-energy-density positive and negative electrode materials and reduce system weight, thus facilitating improvements in energy density.

[0235] 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.

[0236] In this application, unless otherwise specified, "electrode layer" includes electrode active material. The electrode layer can be a positive electrode layer or a negative electrode layer. "Electrode active material" in the electrode layer refers to a material capable of reversibly inserting and extracting active ions. Unless otherwise specified, "negative electrode active material" refers to a material used in the negative electrode layer capable of reversibly inserting and extracting active ions; "positive electrode active material" refers to a material used in the positive electrode layer capable of reversibly extracting and inserting active ions. During solid-state battery charging, active ions are extracted from the positive electrode, pass through the solid electrolyte layer, and insert into the negative electrode; during solid-state battery discharging, active ions are extracted from the negative electrode and insert into the positive electrode. The active ions are not particularly limited; non-limitingly, the active ions can be lithium ions, corresponding to a lithium-ion solid-state battery.

[0237] In this application, unless otherwise specified, "electrode active layer" includes at least one of the positive active layer in the positive electrode layer and the negative active layer in the negative electrode layer. Depending on the specific circumstances, the electrode active layer may refer to either the positive active layer or the negative active layer. It is understood that the positive active layer includes the positive active material and may also be referred to as the "positive active material layer"; the negative active layer includes the negative active material and may also be referred to as the "negative active material layer".

[0238] In a first aspect of this application, a solid-state battery is provided, which includes a positive electrode layer, the positive electrode layer including a positive electrode active layer, the positive electrode active layer including a positive electrode active material and a solid electrolyte material, the positive electrode active material including a coated oxide active material.

[0239] In this application, unless otherwise specified, "coated oxide-based active material" includes a positive electrode active body and a coating layer located on at least a portion of the surface of the positive electrode active body. The coating layer includes lithium metal halide oxide, and the coating thickness of the coating layer in the coated oxide-based active material is relatively uniform. Exemplarily, the uniformity of the coating thickness can be characterized by parameters such as the difference between the maximum and minimum thickness of the coating layer (ΔD), and the ratio of ΔD to D1 (the average thickness of the coating layer), R1, but is not limited thereto. The smaller ΔD and / or R1, the more uniform the coating thickness. The smaller ΔD, the smaller the difference between the maximum and minimum thickness, and the more uniform the coating thickness. The smaller R1, the smaller the fluctuation in coating thickness, and the more uniform the coating thickness. In some embodiments, ΔD ≤ 50 nm. In some embodiments, R1 ≤ 0.5.

[0240] In this application, the difference between the maximum and minimum thickness of the coating layer in the coated oxide active material is denoted as ΔD, the average thickness of the coating layer in the coated oxide active material is denoted as D1, and the ratio of ΔD to D1 is denoted as R1. R1 = ΔD / D1.

[0241] In some embodiments, the coated oxide active material includes a positive electrode active body and a coating layer located on at least a portion of the surface of the positive electrode active body, the coating layer including lithium metal halide oxide.

[0242] In some embodiments, the coated oxide active material includes a positive electrode active material comprising a positive electrode active body and a coating layer located on at least a portion of the surface of the positive electrode active body. The positive electrode active body comprises a lithium transition metal oxide, and the coating layer comprises a lithium metal halide oxide.

[0243] In some embodiments, a solid-state battery is provided, which includes a positive electrode layer, a solid electrolyte layer and a negative electrode layer stacked sequentially, wherein the positive electrode layer includes a positive electrode active layer, and the positive electrode active layer includes a positive electrode active material and a solid electrolyte material;

[0244] The positive electrode active material includes a coated oxide active material, which includes a positive electrode active body and a coating layer located on at least a portion of the surface of the positive electrode active body. The positive electrode active body includes a lithium transition metal oxide, and the coating layer includes a lithium metal halide oxide.

[0245] Coated oxide active materials satisfy one or both of the following characteristics: (v1) ΔD≤50nm; (v2) R1≤0.5.

[0246] In this earlier application, unless otherwise specified, "lithium metal halide oxides" include lithium, non-lithium metal elements, halogens, and oxygen. "Non-lithium metal elements" refers to metal elements other than lithium (Li). Compared to lithium metal oxides composed of the corresponding non-lithium metal elements, lithium, and oxygen, lithium metal halide oxides exhibit higher ionic conductivity.

[0247] In this application, unless otherwise specified, "lithium transition metal oxide" refers to a positive electrode active material containing lithium, transition metal, and oxygen. It is understood that lithium transition metal oxides have the ability to reversibly extract and insert active ions. Therefore, lithium transition metal oxides include non-lithium metal elements, and non-lithium metal elements include transition metal elements. Non-limitingly, in lithium transition metal oxides, the molar percentage of transition metal elements relative to non-lithium metal elements can be 90% to 100%, 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%, 99%, 100%, etc.

[0248] In the coated oxide active material set in the positive electrode active layer, the difference ΔD between the maximum and minimum thickness of the coating layer is low (ΔD≤30nm), which makes the thickness of the coating layer more uniform. In addition, the coating layer contains lithium metal halide oxide with high ionic conductivity, which can significantly reduce the positive electrode interface impedance, significantly reduce the positive electrode interface polarization caused by the coating layer thickness fluctuation, effectively improve the solid phase transport of positive electrode active ions, greatly promote the positive electrode capacity, and significantly improve the cycle performance of solid-state batteries.

[0249] Unless otherwise stated, the improvements described in this application are not intended to be limited to any theoretical constraints.

[0250] By introducing coated oxide-based active materials with high ionic conductivity and good coating uniformity, the interface impedance of the positive electrode can be significantly reduced, which can facilitate the more efficient insertion of active ions into the positive electrode during the first charge and discharge process, thereby significantly improving the coulombic efficiency of solid-state batteries.

[0251] In this application, the uniformity of the coating thickness in the coated oxide active material can also be expressed as the percentage of the coverage area of ​​the coating layer relative to the positive electrode active body (F). A To characterize it. F A The higher the value, the more complete the coverage.

[0252] In this application, the percentage of the coverage area of ​​the coating layer relative to the positive electrode active body in the coated oxide active material is denoted as F. A .

[0253] In some embodiments, the coated oxide-based active 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):

[0254] (a1) ΔD≤30nm; optionally, ΔD≤15nm; further optionally, ΔD≤10nm;

[0255] (a2) R1 is 0 to 0.3, which can be selected as R1 being 0 to 0.25, and can be further selected as 0 to 2;

[0256] (a3)F A ≥80%; optionally, F A The percentage is 80%–100%, with an optional further range of 95%–100%.

[0257] Without limitation, ΔD can be less than or equal to 50nm, or ≤30nm, or ≤15nm, or ≤10nm, or any of the following values, or greater than or equal to 0 and less than or equal to any of the following values, or a range consisting of any two of the following values: 0, 1nm, 2nm, 3nm, 4nm, 5nm, 6nm, 8nm, 10nm, 12nm, 14nm, 15nm, 26nm, 18nm, 20nm, 22nm, 24nm, 25nm, 26nm, 28nm, 30nm, 35nm, 40nm, 45nm, 50nm, etc.

[0258] Non-restrictive, R1 can be less than or equal to 0.5, can also be 0 to 0.3, can be 0 to 0.25, can be 0 to 2, can also be any of the following values, or less than or equal to any of the following non-zero values, or less than any of the following non-zero values, or selected from any two of the following values: 0, 0.001, 0.002, 0.004, 0.005, 0.006, 0.008, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.15, 0.16, 0.18, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, etc.

[0259] By controlling ΔD and / or R1 within a lower range, coated oxide-based active materials with more uniform coating thickness can be provided. This helps to better reduce the polarization of the cathode interface caused by coating thickness fluctuations, and thus improves the cycle performance of solid-state batteries. Furthermore, it also helps to improve the initial coulombic efficiency of solid-state batteries.

[0260] Non-limiting, the percentage of the coverage area of ​​the coating layer relative to the positive electrode active body in a coated oxide-type active material (F A The percentage can be any of the following percentages, or a range consisting of any two of the following percentages: 80%, 82%, 84%, 85%, 86%, 88%, 90%, 94%, 95%, 96%, 98%, 99%, 100%, etc.

[0261] By using the difference between the maximum and minimum thicknesses of the coating layer in the coated oxide active material ΔD, the ratio of the difference between the maximum and minimum thicknesses of the coating layer ΔD to the average thickness D1 R1 (R1 = ΔD / D1), and the percentage of the coating layer's coverage area relative to the positive electrode active body in the coated oxide active material (F... AControlling one or more parameters within the aforementioned range is beneficial for improving the uniformity of the coating layer on the surface of the coated oxide-based active material, and for improving the cycle performance of the solid-state battery. Furthermore, it also helps to improve the initial coulombic efficiency of the solid-state battery.

[0262] In some embodiments, the coated oxide-based active 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] (b1) D1 is 10nm to 100nm, can be 15nm to 100nm, can also be 10nm to 80nm, can be 20nm to 80nm, and can be further selected as 20nm to 60nm (wherein, D1 is the average thickness of the coating layer in the coated oxide active material);

[0264] (b2) The thickness of at least a portion of the coating layer is greater than or equal to 10 nm, and can be selected from 10 nm to 100 nm, further selected from 10 nm to 80 nm, even further selected from 10 nm to 60 nm, and even further selected from 20 nm to 50 nm;

[0265] (b3) In coated oxide-based active materials, the mass percentage of lithium metal halide oxides in the coating layer (F) X1 The percentage is 70%–100%, with an optional range of 80%–100%, and further optional range of 90%–100%.

[0266] (b4) Mass percentage of lithium metal halide oxides in coated oxide-based active materials (F) X0 The concentration is 0.2% to 2%, with an optional concentration of 0.5% to 2%.

[0267] Non-limitingly, the average thickness D1 of the coating layer in the coated oxide active material can be 10 nm to 100 nm, optionally 15 nm to 100 nm, or 10 nm to 80 nm, optionally 20 nm to 80 nm, further optionally 20 nm to 60 nm, or any of the following values ​​or a range selected from any two of the following values: 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, etc.

[0268] Non-limitingly, the thickness of at least a portion of the coating layer can be 10nm to 100nm, optionally 10nm to 80nm, optionally 10nm to 60nm, further optionally 20nm to 50nm, and can also be any of the following values ​​or a range selected from any two of the following values: 10nm, 15nm, 20nm, 25nm, 30nm, 35nm, 40nm, 45nm, 50nm, 55nm, 60nm, 70nm, 80nm, 90nm, 100nm, etc.

[0269] Non-limiting, in coated oxide-based active materials, the mass percentage (F) of lithium metal halide oxide in the coating layer. X1 The percentage can be 70% to 100%, optionally 80% to 100%, further optionally 90% to 100%, further optionally 95% to 100%, or any of the following percentages or a range consisting of any two of the following percentages: 70%, 75%, 80%, 82%, 84%, 85%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 100%, etc.

[0270] Without limitation, the mass percentage (F) of lithium metal halide oxides in coated oxide-based active materials. X0 The percentage can be 0.2% to 2%, optionally 0.5% to 2%, further optionally 1% to 2%, or any of the following percentages or a range composed of any two of the following percentages: 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.2%, 1.4%, 1.5%, 1.6%, 1.8%, 2%, etc., or any of the following ranges: 1.0% to 2.0%, 0.5% to 2.0%, 0.2% to 2.0%, 1.5% to 2%, etc.

[0271] By measuring the average thickness (D1) of the coating layer in the coated oxide active material, the thickness of at least a portion of the coating layer, and the mass percentage (F) of lithium metal halide oxide in the coating layer, the method can be used to determine the composition of the coating layer. X1 ) and the mass percentage of lithium metal halide oxides in coated oxide active materials (F X0 Controlling one or more parameters in the above-mentioned range is beneficial to control the coating amount on the surface of the coated oxide active material to be more suitable, which can significantly reduce the interface impedance of the positive electrode and also help to take into account the energy density of the positive electrode.

[0272] In this application, particle structure analysis methods such as transmission electron microscopy (TEM, such as Talos L120C TEM, Talos F200X, etc.) can be used to detect and analyze whether the positive electrode active material has a coating layer. Elemental analysis methods such as energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD, such as BRAGG110), and inductively coupled plasma spectroscopy (ICP) (such as Thermo Fisher Scientific ICAP XP, Pekin Elmer Optima 5300DV, etc.) can be combined to detect and identify the elemental types and chemical composition of the positive electrode active material and the coating layer. These methods can also be used to determine the coating layer thickness parameters (such as ΔD, D1, R1, etc.) and the content ratio parameters of the coating layer in coated particulate matter (such as coated oxide active materials) (such as F...). X1 F X0 (etc.), parameters related to the degree of coating of the coating layer on the surface of the coated particles (such as F) A ) and other parameters are analyzed.

[0273] For coated oxide-based active materials, particle cutting can be performed using methods such as FIB (Focused Ion Beam, EI Helios Nanolab 450S) and argon ion polishing (CP, such as Hitachi-IM 5000) to obtain cross-sections. The cross-sectional morphology of the particles can then be observed under TEM (Transmission Electron Microscopy). A clear boundary can be observed at the coating interface. Based on the TEM images, the difference between the maximum and minimum thickness of the coating layer (ΔD), the average thickness (D1), and the percentage of the coating layer's coverage area relative to the positive electrode active body (F) can be analyzed and calculated. A R1 (R1 = ΔD / D1) can be calculated. Further analysis using one or more methods, such as energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and inductively coupled plasma optical emission spectrometry (ICP), can confirm the types and content parameters of substances in the coating layer and the positive electrode active material, such as the mass percentage of lithium metal halide oxides in the coating layer (F...). X1 ) and the mass percentage of lithium metal halide oxides in coated oxide active materials (F X0 The number of statistical positions for statistical analysis of ΔD and D1 can be ≥15, optionally ≥20; the number of particles counted can be ≥3, optionally ≥5, further optionally ≥6; the number of statistical positions per particle can be ≥5, optionally ≥10, further optionally ≥20. Statistical F A At that time, the number of particles of the coated oxide active material can be ≥10, or optionally ≥10.

[0274] Solid-state batteries can be disassembled, and the solid materials in the positive electrode active layer can be extracted for particle structure analysis and / or elemental analysis, such as TEM.

[0275] In a non-limiting manner, the composition and content of lithium metal halide oxides can be determined by methods such as XPS and ICP.

[0276] In this application, the positive electrode active material sample can be obtained from a solid-state battery by the following method: disassembling the solid-state cell, extracting the positive electrode active layer material, sonicating with an organic solvent (such as a non-polar solvent, further for example cyclohexane), then dropping the solution onto the sample stage, drying it, and then performing a FIB-TEM selected area test.

[0277] In this application, lithium metal halide oxides include lithium, non-lithium metal elements, halogens, and oxygen. Halides formed by the non-lithium metal elements and halogens in lithium metal halide oxides can be denoted as M halides.

[0278] In some implementations, the M halide 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):

[0279] (c1) The M halide is in a gaseous or liquid state at 120℃~400℃ (optionally 150℃~350℃, further optionally 180℃~300℃), and can be in a gaseous state;

[0280] (c2) The melting point of the M halide is 120℃~400℃, optionally 150℃~350℃, and further optionally 180℃~300℃;

[0281] (c3) The boiling point of the M halide is 120℃~400℃, which can be selected as 150℃~350℃, and further selected as 180℃~300℃.

[0282] In some implementations, the M halide 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):

[0283] (c1') The M halide is in a gaseous or liquid state at 150°C to 350°C, and can be selected as gaseous; optionally, the M halide is in a liquid or gaseous state at 180°C to 300°C, and can be further selected as gaseous;

[0284] The melting point of (c2')M halide is 150℃~350℃, and can be selected as 180℃~300℃;

[0285] The boiling point of (c3')M halides is 150℃~350℃, and can be selected as 180℃~300℃.

[0286] Non-limitingly, the M halide is in a gaseous or liquid state at temperature T1, and may be gaseous. T1 may be 120℃~400℃, may be 150℃~350℃, may be 180℃~300℃, or may be a range consisting of any two of the following temperatures: 120℃, 130℃, 140℃, 150℃, 160℃, 180℃, 200℃, 220℃, 240℃, 250℃, 260℃, 280℃, 300℃, 320℃, 340℃, 350℃, 360℃, 380℃, 400℃, etc.

[0287] Without limitation, the melting point of the M halide can be T1.

[0288] Without limitation, the boiling point of the M halide can be T1.

[0289] In this application, the melting point and / or boiling point of the metal halide (such as M halide) can be confirmed by consulting technical manuals or existing literature, or the melting point and / or boiling point can be tested by existing methods after the chemical composition confirmed by elemental analysis is prepared. For example, it can be confirmed by the following method: TGA-DSC simultaneous thermal analyzer.

[0290] By selecting lithium metal halide oxides in the coating layer that include the aforementioned types, in-situ coating reactions can be carried out using gaseous and / or liquid M halides and residual alkali on the surface of lithium transition metal oxides at relatively low temperatures (e.g., 120℃~400℃) far below the sintering temperature of the positive electrode active material. This allows for the formation of lithium metal halide oxides with high ionic conductivity while also controlling the coating layer to have a relatively uniform thickness distribution.

[0291] In some embodiments, lithium metal halide oxides include lithium, non-lithium metal elements, halogens, and oxygen; wherein, the non-lithium metal elements may include, but are not limited to, one or more of Zr, Ta, Nb, In, W, Ge, Ga, Sb, Sn, Al, and Ti.

[0292] In some embodiments, the halogen in the lithium metal halide oxide may include one or more of F, Cl, Br and I.

[0293] In some embodiments, the halogen in the lithium metal halide oxide includes one or both of F and Cl. In some of these embodiments, the halogen in the lithium metal halide oxide is selected from one or both of F and Cl.

[0294] The aforementioned halides of non-lithium metal elements all have relatively low melting and / or boiling points (e.g., 120°C to 400°C). At relatively low temperatures, these halides of non-lithium metal elements can be controlled to undergo in-situ coating reactions with the surface residual alkali of lithium transition metal oxides in gaseous and / or liquid states, thereby forming coating layers with high ionic conductivity and uniform coating thickness.

[0295] In some embodiments, the atomic molar ratio of halogen to oxygen in the lithium metal halide oxide can be (1-4):(0.8-1.2), optionally (1-5):1, further optionally (2-5):1, or any of the following ratios or a range selected from any two of the following ratios: 1:1, 1.1:1, 1.2:1, 1.25:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.75:1, 1.8:1, 2:1, 2.1:1, 2.2:1, 2.25:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.75:1, 2.8:1, 3:1, 3.2:1, 3.25:1, 3.4:1, 3.5:1, 3.6:1, 3.8:1, 4:1, 4.25:1, 4.5:1, 4.6:1, 4.75:1, 4.8:1, 5:1, etc.

[0296] By controlling the atomic molar ratio of halogens and oxygen in lithium metal halide oxides within the aforementioned range, it is beneficial to balance the high ionic conductivity of the coating, the chemical stability of the coating, and its sensitivity to water.

[0297] In some embodiments, the chemical formula of the lithium metal halide oxide is Li. a M b O c X dThe M element in the lithium metal halide oxide includes one or more of Zr, Ta, Nb, In, W, Ge, Ga, Sb, Sn, Al, and Ti; a is 1 to 2, b is 0.8 to 1.2, c is 0.8 to 1.2, d is 1 to 4, and X is a halogen. Non-limitingly, a can be any of the following values ​​or a range selected from any two of the following values: 1, 1.1, 1.2, 1.25, 1.3, 1.4, 1.5, 1.6, 1.7, 1.75, 1.8, 1.9, 2, etc. Non-limitingly, b and c can each independently be any of the following values ​​or a range selected from any two of the following values: 0.8, 0.9, 1, 1.1, 1.2, etc. Without limitation, d can be any of the following values ​​or a range consisting of any two of the following values: 1, 1.1, 1.2, 1.25, 1.3, 1.4, 1.5, 1.6, 1.7, 1.75, 1.8, 2, 2.1, 2.2, 2.25, 2.3, 2.4, 2.5, 2.6, 2.75, 2.8, 3, 3.2, 3.25, 3.4, 3.5, 3.6, 3.8, 4, etc.

[0298] In some embodiments, lithium metal halide oxides include those with the chemical formula Li. a M b O c X d The substance.

[0299] In some embodiments, the X element in the lithium metal halide oxide includes one or both of F and Cl, and may be further selected from one or both of F and Cl.

[0300] In some embodiments, the X element in the lithium metal halide oxide is F or Cl.

[0301] In some embodiments, the D of the positive electrode active material v 50 is 1μm to 8μm, and can be selected from 3μm to 6μm, where D v 50 represents the particle size at which the cumulative volume distribution percentage of the multi-particle mixture reaches 50%.

[0302] Non-limiting, the D of the positive electrode active material v 50 can be 1μm to 8μm, can be selected from 3μm to 6μm, or can be any of the following values ​​or a range composed of any two of the following values: 1μm, 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 4.5μm, 5μm, 5.5μm, 6μm, 6.5μm, 7μm, 7.5μm, 8μm, etc.

[0303] Unless otherwise stated in this application, D v50 refers to the particle size corresponding to a cumulative volume distribution percentage of 50% in 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. Those skilled in the art will understand D v The meaning of 50 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 2000E laser particle size analyzer from Malvern Instruments Ltd. (UK) or the LS-909 laser particle size analyzer (Omega). The standard procedure for determining the material's D value can be referenced in GB / T19077-2016 / ISO 13320:2009. v 50 is tested. The detailed test procedure includes: taking an appropriate amount of the sample to be tested, adding solvent (the solvent can be deionized water, and the sample concentration can be controlled at 8%~12% opacity), sonicating for 5 minutes (53KHz / 120W) to fully disperse the sample, and then measuring the sample according to GB / T19077-2016 / ISO 13320:2009 standard. 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. To avoid agglomeration during the drying process affecting particle size testing, a dispersion test was performed on the washed and moistened sample, using the solvent as specified.

[0304] By using the D of the positive electrode active material v Controlling the 50 within the aforementioned range is beneficial for forming a uniform coating, achieving better intrinsic interface contact, and better balancing the reduction of positive electrode interface impedance and positive electrode energy density.

[0305] The relatively small particle size of the positive electrode active material is beneficial to further improve the interfacial contact of the positive electrode and to better reduce the interfacial impedance of the positive electrode.

[0306] Coated oxide-based active materials include at least a positive electrode active body. The "positive electrode active body" is the fundamental part of the coated oxide-based active material that has the ability to reversibly extract and insert active ions.

[0307] In some implementations, the positive electrode active body comprises a lithium transition metal oxide.

[0308] In this application, unless otherwise specified, the definition of lithium transition metal oxides encompasses lithium transition metal oxides and their modified forms. Modified forms of lithium transition metal oxides include the lithium transition metal oxide itself and modifying elements. Modifying elements may include one or more of doping elements and coating elements. Modified forms of lithium transition metal oxides still fall within the scope of lithium transition metal oxides.

[0309] In this application, unless otherwise specified, "a modified positive electrode active material" includes the positive electrode active material itself and the modifying element. Furthermore, the modifying element may exist as a dopant element, a coating element, or a combination of a dopant element and a coating element. Unless otherwise specified, "a modified positive electrode active material" still falls within the scope of positive electrode active materials.

[0310] Non-limitingly, lithium transition metal oxides may include, but are not limited to, lithium transition metal oxides known in the art that can be used as cathode active materials in solid-state batteries. Examples of lithium transition metal oxides may include, but are not limited to, one or more of lithium cobalt oxides, lithium nickel oxides, lithium manganese oxides, lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, lithium nickel cobalt manganese oxides, lithium nickel cobalt aluminum oxides, and their modifications. Non-limiting examples of lithium nickel cobalt manganese oxides may include LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 LiNi 0.6 Co 0.3 Mn 0.1 O2 (also known as NCM) 631 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 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 (e.g., lithium nickel oxides can be LiNiO2. Non-limiting examples of lithium nickel manganese oxides can include LiNi...) 0.5 Mn 1.5 O2, etc. Non-limiting examples of lithium nickel cobalt aluminum oxides may include LiNi. 0.80 Co 0.15 Al 0.05 O2.

[0311] In some embodiments, the lithium transition metal oxide has a layered crystal structure.

[0312] In some embodiments, the lithium transition metal oxide includes one or more of lithium nickel-based oxides, lithium-rich manganese-based cathode active materials, spinel lithium manganate, and lithium cobaltate.

[0313] In the present application, unless otherwise specified, "lithium nickel-based oxide" refers to a lithium transition metal oxide that includes lithium element, nickel element, and oxygen element. At this time, the non-lithium metal element in the lithium transition metal oxide includes nickel element. Without limitation, the lithium nickel-based oxide may include one or more of lithium nickel cobalt manganese-based oxides and lithium nickel cobalt aluminum-based oxides.

[0314] In some embodiments, the lithium nickel-based oxide includes a lithium transition metal oxide with the chemical formula Li x (Ni a Co b M’ c M” d )O 2-e , where 0.6 ≤ x ≤ 1.2, 0 < a < 1, 0 < b < 1, 0 < c < 1, 0 ≤ d < 1 (optionally, 0 < d < 1), a + b + c + d = 1, -0.2 ≤ e ≤ 0.4 (optionally, -0.1 ≤ e ≤ 0.1). M’ may include at least one of Mn and Al. M” may include one or more of Na, K, Ca, Ba, Sb, Ti, Zr, W, Sr, Nb, Mo, Si, Mg, B, Cr, and Ta. Without limitation, the value or value range of x can refer to the value or value range of x2. The value of a can refer to the value or value range of q1. Without limitation, the value of b can refer to the value or value range of q4. Without limitation, the value of c can refer to the value or value range of q5. Without limitation, (2 - e) can refer to the value or value range of x3. In some of these embodiments, M’ is the Mn element.

[0315] In the present application, unless otherwise specified, "lithium-rich manganese-based cathode active material" refers to a lithium transition metal oxide containing Li2MnO3, and may also optionally contain LiMO2, where M is a transition metal element. Without limitation, M may 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 cathode 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 cathode active material is y(Li2MnO3)·(1 - y)(LiMO2), where 0 < y ≤ 1, optionally, 0 < y < 1. In some embodiments, the lithium-rich manganese-based cathode active material is a layered lithium-rich manganese-based cathode active material.

[0316] Unless otherwise stated in this application, "lithium spinel manganese oxide" refers to LiMn2O4 with a spinel structure, which has a three-dimensional tunnel structure that can provide a fast diffusion channel for lithium ions. It has advantages such as good rate performance and low cost, and can operate under some high voltage conditions.

[0317] In some embodiments, the lithium transition metal oxide includes a lithium nickel-based oxide; wherein the lithium nickel-based oxide includes Li, a non-lithium metal element, and O, and the non-lithium metal element includes Ni.

[0318] In this application, unless otherwise specified, "lithium nickel-based oxide" refers to lithium transition metal oxides containing nickel. It is understood that lithium nickel-based oxides include lithium, non-lithium metals, and oxygen, with nickel being one of the non-lithium metals.

[0319] In this application, the atomic molar ratio of Ni to non-lithium metal elements in lithium nickel-based oxides is denoted as q1; the atomic molar ratio of Ni to Li in lithium nickel-based oxides is denoted as q2:x2; and the atomic molar ratio of Ni to O in lithium nickel-based oxides is denoted as q3:x3. When the lithium nickel-based oxide contains Co, the atomic molar ratio of Co to non-lithium metal elements in the lithium nickel-based oxide is denoted as q4. When the lithium nickel-based oxide contains Mn, the atomic molar ratio of Mn to non-lithium metal elements in the lithium nickel-based oxide is denoted as q5.

[0320] In some implementations, the lithium nickel-based oxide contains the element Co.

[0321] In some embodiments, the lithium nickel-based oxide contains the element Mn.

[0322] In some embodiments, the lithium nickel-based oxide has a layered crystal structure.

[0323] In some embodiments, the lithium transition metal oxide 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):

[0324] (i1) The atomic molar ratio of Ni to non-lithium metal elements in lithium nickel-based oxides is q1, where 0.5≤q1≤1;

[0325] (i2) The lithium nickel-based oxide contains Ni and Li elements in an atomic molar ratio of q2:x2, wherein 0.5≤q2≤1 and 0.6≤x2≤1.2;

[0326] (i3) The lithium nickel-based oxide contains Ni and O elements in an atomic molar ratio of q3:x3, wherein 0.5≤q3≤1 and 1.6≤x3≤2.2;

[0327] (i4) Lithium nickel-based oxides contain the element Co;

[0328] (i5) Lithium nickel-based oxides contain the element Mn;

[0329] (i6) Lithium nickel-based oxides have a layered crystal structure.

[0330] In some embodiments, the lithium transition metal oxide 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):

[0331] (t1)0.6≤q1≤1; optionally, 0.6≤q1≤0.96;

[0332] (t2)0.6≤q2≤1; optionally, 0.6≤q2≤0.96;

[0333] (t3)0.6≤x2≤1.1;

[0334] (t4)0.6≤q3≤1; optionally, 0.6≤q3≤0.96;

[0335] (t5)1.8≤x3≤2.1;

[0336] (t6) The lithium nickel-based oxide contains the element Co, and the atomic molar ratio of the element Co to the non-lithium metal elements in the lithium nickel-based oxide is q4, where 0.02≤q4≤0.35;

[0337] (t7) The lithium nickel-based oxide contains the element Mn, and the atomic molar ratio of the element Mn to the non-lithium metal elements in the lithium nickel-based oxide is q5, where 0.01≤q5≤0.38;

[0338] (t8) The mass percentage of lithium nickel-based oxides in lithium transition metal oxides is 80% to 100%.

[0339] In some embodiments, the lithium transition metal oxide 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):

[0340] (t1')0.5≤q1≤0.99; optionally, 0.5≤q1≤0.9; optionally, 0.5≤q1≤0.8;

[0341] (t2')0.5≤q2≤0.99; optionally, 0.5≤q2≤0.9; optionally, 0.5≤q2≤0.8;

[0342] (t3')0.8≤x2≤1.1;

[0343] (t4')0.5≤q3≤0.99; optionally, 0.5≤q3≤0.9; optionally, 0.5≤q3≤0.8;

[0344] (t5')1.8≤x3≤2.06;

[0345] (t6') Lithium nickel-based oxides contain Co, with a concentration of 0.05 ≤ q4 ≤ 0.25;

[0346] (t7') Lithium nickel-based oxides contain Mn element, 0.05≤q5≤0.3;

[0347] (t8') The mass percentage of lithium nickel-based oxides in lithium transition metal oxides is 90%–100%;

[0348] (t9') Lithium transition metal oxides include lithium nickel cobalt manganese-based oxides, wherein, optionally, the lithium nickel cobalt manganese-based oxides account for 80% to 100% of the mass of the lithium transition metal oxides, and more preferably 90% to 100%.

[0349] (t10') Lithium transition metal oxides include lithium nickel cobalt manganese-based oxides; in lithium nickel cobalt manganese-based oxides, the ratio of the sum of the atomic molar ratios of nickel, cobalt, and manganese to the sum of the atomic molar ratios of non-lithium metal elements is denoted as R. NCM R NCM The value is 0.9 to 1; optionally, R NCM It ranges from 0.95 to 1.

[0350] Without limitation, q1, q2 and q3 can each be independently any of the following values, or selected from a range consisting of any two of the following values: 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 0.96, 0.97, 0.98, 0.99, 1, etc.

[0351] In existing solid-state batteries, when the positive electrode active material includes lithium nickel-based oxides with high nickel content, such as ternary positive electrode materials with high nickel content, physical and / or chemical changes are prone to occur at high potentials, leading to deterioration of the interface contact and potentially causing interface failure.

[0352] By depositing a coating layer containing lithium metal halide oxide with good coating uniformity on the surface of a lithium nickel-based oxide with high nickel content, the prepared coated oxide active material has a positive electrode active body comprising a lithium nickel-based oxide with high nickel content (the nickel content can be referred to as one or more parameters q1, q2, and q3). In this case, the high ionic conductivity of the lithium metal halide oxide, combined with its excellent coating uniformity, can significantly reduce the positive electrode interface impedance, improve the positive electrode interface stability, and significantly improve the cycle performance of solid-state batteries. Furthermore, it can also significantly improve the initial coulombic efficiency.

[0353] Without limitation, x2 can be any of the following values, or a range consisting of any two of the following values: 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1, 1.05, 1.1, 1.15, 1.2, etc.

[0354] Without limitation, x3 can be any of the following values, or a range consisting of any two of the following values: 1.6, 1.7, 1.8, 1.9, 2, 2.05, 2.06, 2.08, 2.1, 2.2, etc.

[0355] Without limitation, q4 can be any of the following values, or a range consisting of any two of the following values: 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.1, 0.12, 0.14, 0.15, 0.16, 0.18, 0.2, 0.22, 0.24, 0.25, 0.26, 0.28, 0.3, 0.32, 1 / 3, 0.34, 0.35, etc.

[0356] Without limitation, q5 can be any of the following values, or a range selected from any two of the following values: 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.1, 0.12, 0.14, 0.15, 0.16, 0.18, 0.2, 0.22, 0.24, 0.25, 0.26, 0.28, 0.3, 0.32, 1 / 3, 0.34, 0.35, 0.36, 0.38, 0.4, 0.42, 0.44, 0.45, 0.46, 0.48, 0.5, etc.

[0357] Non-limitingly, the mass percentage of lithium nickel-based oxide in lithium transition metal oxide 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%, 98%, 100%, etc.

[0358] In some embodiments, the lithium transition metal oxide includes lithium nickel cobalt manganese-based oxides.

[0359] In this application, unless otherwise specified, "lithium nickel cobalt manganese-based oxide" refers to a lithium transition metal oxide comprising lithium, nickel, cobalt, manganese, and oxygen, and more specifically, a lithium nickel-based oxide. It is understood that lithium nickel cobalt manganese-based oxide includes lithium, non-lithium metal elements, and oxygen, wherein the non-lithium metal elements include nickel, cobalt, and manganese. In this application, unless otherwise specified, lithium nickel cobalt manganese-based oxides used as positive electrode active materials typically have a layered structure.

[0360] In lithium nickel cobalt manganese-based oxides, the ratio of the sum of the atomic molar ratios of nickel, cobalt, and manganese to the sum of the atomic molar ratios of non-lithium metal elements is denoted as R. NCM In a non-restrictive sense, R NCM It can be 0.9 to 1, can be selected from 0.95 to 1, or can be any of the following values, or selected from a range consisting of any two of the following values: 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1, etc.

[0361] In lithium nickel cobalt manganese-based oxides, the ratio of the atomic molar ratio of nickel to the sum of the atomic molar ratios of nickel, cobalt, and manganese is denoted as R. Ni The ratio of the atomic molar ratio of cobalt to the sum of the atomic molar ratios of nickel, cobalt, and manganese is denoted as R. Co The ratio of the atomic molar ratio of manganese to the sum of the atomic molar ratios of nickel, cobalt, and manganese is denoted as R. Mn .

[0362] Without limitation, R Ni It can be any of the following values, or a range selected from any two of the following values: 0.5, 0.55, 0.6,

[0363] 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 0.96, 0.97, 0.98, 0.99, 1, etc. R Ni You can also refer to the values ​​or ranges of q1 mentioned above.

[0364] Without limitation, R Co It can be any of the following values, or a range selected from any two of the following values: 0.02, 0.03, 0.04,

[0365] 0.05, 0.06, 0.07, 0.08, 0.1, 0.12, 0.14, 0.15, 0.16, 0.18, 0.2, 0.22, 0.24, 0.25, 0.26, 0.28, 0.3

[0366] 0.32, 1 / 3, 0.34, 0.35, etc. R Co You can also refer to the values ​​or ranges of q4 mentioned above.

[0367] Without limitation, R Mn It can be any of the following values, or a range selected from any two of the following values: 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.1, 0.12, 0.14, 0.15, 0.16, 0.18, 0.2, 0.22, 0.24, 0.25, 0.26, 0.28, 0.3, 0.32, 1 / 3, 0.34, 0.35, 0.36, 0.38, 0.4, 0.42, 0.44, 0.45, 0.46, 0.48, 0.5, etc. R Mn You can also refer to the values ​​or ranges of q5 mentioned above.

[0368] Non-limitingly, the mass percentage of lithium nickel cobalt manganese-based oxide in lithium transition metal oxide can be 80% to 100%, further 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%, 98%, 100%, etc.

[0369] In some embodiments, the lithium transition metal oxide includes a ternary cathode material, which may be selected as a ternary cathode material. In this application, the "ternary cathode material" is composed of Li, nickel, cobalt, M2, and oxygen; wherein, M2 can be manganese or aluminum. When M2 is manganese (Mn), the ternary cathode material is lithium nickel cobalt manganese oxide, which can be denoted as NCM; when M2 is aluminum (Al), the ternary cathode material is lithium nickel cobalt aluminum oxide, which can be denoted as NCA.

[0370] By incorporating the aforementioned types of lithium transition metal oxides into coated oxide-based active materials, it is beneficial to improve the energy density of solid-state batteries. When the lithium transition metal oxide includes lithium nickel-based oxides, controlling the nickel content within the aforementioned range is beneficial to improving the structural stability of the cathode active material at high voltages (e.g., 4.0V–4.8V, further such as 4.0V–4.5V). Furthermore, lithium-rich manganese-based cathode active materials, spinel lithium manganese oxide, and lithium cobalt oxide also exhibit good structural stability at high voltages.

[0371] Those skilled in the art can use one or more elemental analysis methods, including but not limited to energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and inductively coupled plasma optical emission spectrometry (ICP), to perform compositional analysis on the positive electrode active material in the positive electrode layer.

[0372] 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.

[0373] In some embodiments, the positive electrode active 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):

[0374] (e1) The ionic conductivity of lithium metal halide oxides at 25 °C is 1 mS / cm~10 mS / cm;

[0375] (e2) The ionic conductivity of the positive electrode active material at 25℃ is greater than or equal to 0.01 mS / cm;

[0376] (e3) The ionic conductivity of the positive electrode active material or the coated oxide active material at 25℃ is greater than or equal to 0.01 mS / cm.

[0377] In some embodiments, the ionic conductivity of lithium metal halide oxide at 25°C can be 1 mS / cm to 10 mS / cm, or any of the following values ​​or a range selected from any two of the following values: 1 mS / cm, 2 mS / cm, 3 mS / cm, 4 mS / cm, 5 mS / cm, 6 mS / cm, 7 mS / cm, 8 mS / cm, 9 mS / cm, 10 mS / cm, etc.

[0378] In some embodiments, the ionic conductivity of the positive electrode active material at 25°C is greater than or equal to 0.01 mS / cm.

[0379] In some embodiments, the ionic conductivity of the coated oxide-based active material at 25°C is greater than or equal to 0.01 mS / cm.

[0380] In this application, "ionic conductivity" has a well-known meaning in the art, and the ionic conductivity of lithium metal halide oxides can be obtained by using conventional testing methods in the art. The "25°C ionic conductivity" of lithium metal halide oxides refers to the ionic conductivity measured at a test temperature of 25°C. The "25°C ionic conductivity" of the positive electrode active material refers to the ionic conductivity measured at a test temperature of 25°C.

[0381] The ionic conductivity of solid materials can be tested using electrochemical impedance spectroscopy (EIS): The solid material is placed into a mold of a certain diameter and pressed into a membrane under a certain pressure. The membrane is then tested using electrochemical impedance spectroscopy (EIS) with an impedance analyzer, and the ionic conductivity of the membrane is calculated based on the impedance value. The diameter of the membrane can be 10 mm.

[0382] More specifically, the ionic conductivity of solid materials can be tested using the following method: A cylindrical stainless steel current collector of a certain diameter (e.g., 10 mm) is used to clamp the diaphragm under test in a mold under a certain pressure (e.g., 300 MPa). The current collector is then connected to an electrochemical workstation with a bias voltage of 10 mV and a frequency range of 10... 6 Hz to 10 -2 Electrochemical impedance spectroscopy (EIS) was performed on the membrane under test within the Hz range. The intersection point of the electrochemical impedance spectrum curve from the high-frequency band to the low-frequency band with the Z' axis was recorded as the resistance value R. The ionic conductivity of the membrane under test can be calculated using formula (1):

[0383] Where d is the diaphragm thickness and A is the contact area between the diaphragm and the current collector.

[0384] The following steps can be used to test the ionic conductivity of coated oxide active materials or positive electrode active materials at 25℃: Press 100mg of the test material into a mold at 10MPa (corresponding to the positive electrode active layer), then add Li6PS5Cl sulfide electrolyte powder to the other two sides respectively, and press twice at 300MPa respectively. Then, add indium sheets and composite copper-lithium sheets to the outside of the two sides respectively, and perform impedance testing. Calculate the ionic conductivity based on the impedance value and the thickness of the positive electrode active layer. It is also necessary to separately test the impedance of lithium indium|Li6PS5Cl|lithium indium without the test material. Subtract the impedance of the latter from the former impedance to obtain the actual impedance value R.

[0385] In this application, the solid electrolyte material in the positive electrode active layer is referred to as "positive electrode electrolyte material".

[0386] In some embodiments, the solid electrolyte material in the positive electrode active layer includes a sulfide solid electrolyte.

[0387] For solid-state batteries with cathode active materials including coated oxide-based active materials and solid electrolyte materials including sulfide solid electrolytes, on the one hand, the introduction of coated oxide-based active materials helps reduce cathode interfacial impedance and polarization, significantly improving the cycle performance of solid-state batteries. On the other hand, sulfide solid electrolytes have excellent high ionic conductivity, and the coating layer in the coated oxide-based active material can effectively reduce the direct contact between the lithium transition metal oxide inside the coated oxide-based active material and the sulfide solid electrolyte, which helps to significantly suppress the decomposition effect of oxygen released from the lithium transition metal oxide lattice on the sulfide solid electrolyte. This significantly improves the interfacial stability between the cathode active material and the solid electrolyte material, and significantly enhances the structural stability and ion-conducting stability of the solid electrolyte material. Based on the aforementioned multiple effects, it is beneficial to better improve the cycle performance of solid-state batteries. In addition, it is also beneficial to better improve the first coulombic efficiency of solid-state batteries.

[0388] 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.

[0389] Unless otherwise specified, the sulfide electrolyte of the sulfide type has a sulfide-germanium type crystal phase structure. Without limitation, the sulfide electrolyte of the sulfide type may include compounds 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 1 It 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 It can be selected from one or more elements chosen from Cl, Br, I, and F. In some embodiments, X 1 For halogens, further, X 1 It can be selected from one or more elements of Cl, Br, I and F.

[0390] 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 Ge1-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 One or more elements selected from O, Se, Te, Cl, Br, I, and F.

[0391] 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.

[0392] Without limitation, sulfide solid electrolytes can include Li 7-y PS5Cl y Li 10 GeP2S 12 One or more of Li3PS4, but not limited to these. Wherein, y can be 0.5 to 1.6.

[0393] In some implementations, the positive electrode active layer 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):

[0394] (d1) The mass percentage of coated oxide active materials in the positive electrode active materials is 80% to 100%, and can be selected as 90% to 100%;

[0395] (d2) The mass percentage of the coated oxide active material in the positive electrode active layer is 70% to 98%, and can be selected as 75% to 95%;

[0396] (d3) The mass percentage of solid electrolyte material in the positive electrode active layer is 2% to 30%, and can be selected as 5% to 25%;

[0397] (d4) Solid electrolyte materials include sulfide solid electrolytes; the mass percentage of sulfide solid electrolytes in the positive electrode active layer is 2% to 30%, and can be selected as 5% to 25%.

[0398] Without limitation, the mass percentage (F) of coated oxide active materials in the positive electrode active material. M1 The percentage can be 80% to 100%, or optionally 90% to 100%, or any of the following percentages or a range consisting of any two of the following percentages: 80%, 82%, 84%, 85%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 100%, etc.

[0399] Without limitation, the mass percentage (F) of the coated oxide-based active material in the positive electrode active layer M0 The percentage can be 70% to 98%, or 75% to 95%, or any of the following percentages or a range of any two of the following percentages: 70%, 72%, 74%, 75%, 76%, 78%, 80%, 82%, 84%, 85%, 86%, 88%, 90%, 92%, 94%, 95%, 96%, 98%, etc.

[0400] By measuring the mass ratio (F) of coated oxide active materials in the positive electrode active material M1 ) and the mass percentage of coated oxide active materials in the positive electrode active layer (F M0 Controlling one or two parameters within the aforementioned range is more conducive to reducing the positive electrode interface impedance and improving the cycle performance of solid-state batteries through coated oxide active materials.

[0401] In some embodiments, the mass percentage of the solid electrolyte material in the positive electrode active layer can be 2% to 30%, optionally 5% to 25%, further optionally 5% to 20%, even further optionally 5% to 15%, or any of the following percentages, or a range selected from any two of the following percentages: 5%, 6%, 8%, 10%, 12%, 14%, 15%, 16%, 18%, 20%, 22%, 24%, 25%, 26%, 28%, 30%, etc.

[0402] In some embodiments, the mass percentage of the sulfide solid electrolyte in the positive electrode active layer is 5% to 30%, optionally 5% to 25%, further optionally 5% to 20%, and even more preferably 5% to 15%. It can also be any of the following percentages, or a range selected from any two of the following percentages: 5%, 6%, 8%, 10%, 12%, 14%, 15%, 16%, 18%, 20%, 22%, 24%, 25%, 26%, 28%, 30%, etc.

[0403] By measuring the mass ratio (F) of coated oxide active materials in the positive electrode active material M1 ), the mass percentage of coated oxide active materials in the positive electrode active layer (F) M0 Controlling one or more parameters, such as the mass percentage of solid electrolyte material in the positive electrode active layer and the mass percentage of sulfide solid electrolyte in the positive electrode active layer, within the aforementioned range is beneficial for better promoting the synergistic effect of coated oxide active materials and positive electrode electrolyte materials (such as sulfide solid electrolytes) in improving the cycle performance of solid-state batteries.

[0404] In some embodiments, the mass percentage of the sulfide solid electrolyte in the positive electrode active layer can be greater than or equal to 5% and less than 15%, and can be selected from 5% to 12%, further selected from 5% to 10%, or can be any of the following percentages, or selected from any two of the following percentages: 5%, 6%, 7%, 8%, 9%, 10%, etc.

[0405] In some embodiments, the mass percentage of solid electrolyte material in the positive electrode active layer can be greater than or equal to 5% and less than 15%, and can be selected from 5% to 12%, further selected from 5% to 10%, or can be any of the following percentages, or selected from any two of the following percentages: 5%, 6%, 7%, 8%, 9%, 10%, etc.

[0406] By introducing coated oxide-based active materials, the amount of cathode electrolyte materials (such as sulfide solid electrolytes) can be reduced while maintaining good specific capacity of the cathode, thereby improving the energy density of solid-state batteries.

[0407] In some implementations, the solid-state battery is an all-solid-state battery.

[0408] 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, negative electrode layer and electrolyte part are all made of solid materials, and no liquid electrolyte is provided in the battery, so it can be called "all-solid-state battery".

[0409] In some implementations, the solid-state battery is a lithium-ion secondary battery; in this case, the active ions include lithium ions.

[0410] In some implementations, the solid-state battery is an all-solid-state lithium-ion secondary battery, which is both an all-solid-state battery and a lithium-ion secondary battery.

[0411] In some embodiments, the charging cutoff voltage of the solid-state battery is 2.5V to 4.8V, optionally 3.8V to 4.8V, further optionally 4.0V to 4.8V, further optionally 4.0V to 4.5V, and may also be any of the following voltages or a range selected from any two of the following voltages: 2.5V, 2.6V, 2.8V, 3.0V, 3.2V, 3.4V, 3.5V, 3.6V, 3.8V, 4.0V, 4.2V, 4.4V, 4.5V, 4.6V, 4.8V, etc.

[0412] In some implementations, the solid-state battery has a charging cutoff voltage greater than or equal to 4.0V, and optionally, greater than 4.0V.

[0413] In some implementations, the solid-state battery has a charging cutoff voltage greater than or equal to 4.2V, and optionally greater than 4.2V.

[0414] In some implementations, the solid-state battery has a charging cutoff voltage greater than or equal to 4.3V, and optionally greater than 4.3V.

[0415] In this application, unless otherwise specified, the "charging cut-off voltage" of a solid-state battery has a well-known meaning in the art and is usually marked on battery products. Solid-state battery products can operate at voltages equal to or lower than the charging cut-off voltage. Taking a lithium-ion solid-state battery as an example, as charging progresses, the battery voltage continuously rises; when the charging cut-off voltage is reached, it indicates that the distribution of lithium ions in the positive and negative electrode materials and the electrochemical equilibrium inside the battery have reached a specific state. If charging continues at a high current, exceeding the charging cut-off voltage, irreversible chemical reactions can easily occur inside the battery.

[0416] 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.

[0417] 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.

[0418] 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, the positive electrode layer, negative electrode layer and electrolyte part are all made of solid materials, and no liquid electrolyte is provided in the battery cell, so it can be called "all-solid-state battery cell".

[0419] Non-limitingly, a solid-state battery cell (which can be an all-solid-state battery cell) may include a positive electrode layer, a solid electrolyte layer, and a negative electrode layer, with the solid electrolyte layer located between the positive and negative electrode layers. During battery charging and discharging, active ions shuttle between the positive and negative electrode layers, inserting and extracting. The solid electrolyte layer serves to conduct ions between the positive and negative electrode layers and also isolates them, thus preventing short circuits between the positive and negative electrodes.

[0420] In some embodiments, the solid-state battery cell 5 includes a solid-state cell 52.

[0421] In some implementations, the solid-state cell is an all-solid-state cell.

[0422] In some embodiments, the solid-state cell 52 (which may be an all-solid-state cell) includes a positive electrode layer, a solid electrolyte layer, and a negative electrode layer stacked sequentially.

[0423] In a non-limiting manner, the positive electrode layer, the solid electrolyte layer, and the negative electrode layer can be assembled in a stacked manner, with the solid electrolyte layer placed between the positive electrode layer and the negative electrode layer.

[0424] The following is a description of the positive electrode layer.

[0425] The positive electrode layer can be formed based on a solid electrolyte membrane or provided by a pre-fabricated positive electrode sheet, which can be a positive electrode sheet that is available in the art for use in solid-state batteries.

[0426] Positive electrode sheets can be prepared using dry or wet methods. For example, they can be dry-pressed into films. Alternatively, they can be wet-coated and dried to form films.

[0427] 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.

[0428] Unless otherwise stated, the positive electrode layer in this application includes at least a positive electrode active layer.

[0429] Unless otherwise stated in this application, the positive electrode sheet includes at least a positive active layer.

[0430] 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". The positive electrode electrolyte material can enhance the ion conductivity of the positive electrode layer, reduce interfacial impedance, and promote the charge transfer efficiency and full release of the capacity of the positive electrode active material with the external environment.

[0431] The types of positive electrode active materials in the positive electrode active layer can be referred to in the context of this application. Optionally, other types of positive electrode active materials known in the art that can be used in the positive electrode layer of solid-state batteries may also be included.

[0432] Non-limitingly, the mass percentage of the positive electrode active material in the positive electrode active layer can be ≥70%, or 70% to 98%, or even 75% to 95%, 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%, 95%, 96%, 98%, etc.

[0433] The types and contents of solid electrolyte materials in the positive electrode active layer can be found in the context of this application. Optionally, other types of solid electrolyte materials known in the art that can be used in the positive electrode layer of solid-state batteries may also be included.

[0434] 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, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the positive electrode conductive agent may include, but is not limited to, one or more of SP, KS-6, acetylene black, branched Ketjen black ECP, SFG-6, vapor-grown carbon fiber VGCF, carbon nanotubes (CNTs), graphene, and graphene oxide. Non-limitingly, the mass percentage of the positive electrode conductive agent in the positive electrode active layer may be 0–10%, more preferably 0–8%, further preferably 0–5%, further preferably 0.1%–5%, further preferably 0.1%–3%, and further preferably 0.5%–3%. When a positive electrode component, including a positive electrode active material, is prepared into a positive electrode active layer using a dry method, a positive electrode conductive agent can be added to the positive electrode component to improve the conductivity of the positive electrode active layer.

[0435] In some embodiments, the positive electrode active layer is composed of a conductive agent, a positive electrode electrolyte material, and a positive electrode active material in a mass ratio of 1:(10-12):(40-45). In some embodiments, the positive electrode active material is a coated oxide-based active material.

[0436] In some embodiments, the positive electrode active layer optionally includes a binder (which may be referred to as a positive electrode binder). As a non-limiting example, the positive electrode binder may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a terpolymer of PVDF-tetrafluoroethylene-propylene, a terpolymer of PVDF-hexafluoropropylene-tetrafluoroethylene, a tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resins. Typically, the mass percentage of the positive electrode binder in the positive electrode active layer can be 0–10%, more commonly 0–8%, further commonly 0.1%–5%, further commonly 0.5%–5%, and further commonly 0.5%–3%. By preparing the positive electrode active layer after wet-processing the positive electrode composition including the positive electrode active material into a positive electrode slurry, the positive electrode binder can be placed in the positive electrode slurry, which can assist film formation and also facilitate the formation of a good electrical contact network between the positive electrode active materials in the positive electrode layer in solid-state batteries.

[0437] As a non-limiting example, the positive current collector has two surfaces that are opposite to each other in its own thickness direction, and the positive active layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0438] 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).

[0439] Positive electrode sheets can be prepared using dry or wet methods. For example, they can be dry-pressed into films. Alternatively, they can be wet-coated and dried to form films.

[0440] In some embodiments, the positive electrode sheet can be prepared by: dry mixing the components used to prepare the positive electrode sheet, such as the positive electrode active material, positive electrode electrolyte material, positive electrode conductive agent, positive electrode binder, and any other components; then heating and pressurizing the mixed material to knead it into a clump; hot rolling pressing to form a self-supporting positive electrode sheet; and hot rolling bonding the self-supporting positive electrode sheet with a positive electrode current collector, wherein the self-supporting positive electrode sheet can be bonded to at least one side (single or double sides) of the positive electrode current collector to obtain the positive electrode sheet. Non-limitingly, a dual planetary mixer can be used for dry mixing. Non-limitingly, a kneading and pressing process can be performed using a Banbury mixer. Non-limitingly, the temperature for hot rolling pressing can be 75°C to 85°C, and further, such as 78°C, 80°C, 82°C, etc. The method of assembling solid-state batteries using positive electrode sheets is suitable for industrial mass production.

[0441] 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 an 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 cold pressing (optional), the positive electrode sheet is obtained. The optional cold pressing process can be performed using a cold rolling mill. Taking a sulfide solid electrolyte as an example, the organic solvent in the positive electrode slurry can include one or more of p-xylene, trimethylbenzene, butyl butyrate, heptane, etc., and more specifically, p-xylene. The surface of the positive electrode current collector coated with the positive electrode slurry can be a single surface of the positive electrode current collector or both surfaces of the positive electrode current collector. The solid content of the positive electrode slurry can be 40wt% to 80wt%. The viscosity of the positive electrode slurry at room temperature can be adjusted to 5000 mPa·s to 25000 mPa·s. 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 .

[0442] 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 .

[0443] 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.

[0444] The following is a description of the negative electrode layer.

[0445] The negative electrode layer can be formed based on a solid electrolyte membrane or provided by a pre-fabricated negative electrode sheet, which can be a negative electrode sheet that is available in the art for use in solid-state batteries.

[0446] Negative electrode sheets can be prepared using either dry or wet methods. For example, they can be dry-pressed into films under low pressure conditions, such as 1 MPa to 2 MPa. Alternatively, they can be wet-coated into films.

[0447] In this application, unless otherwise specified, the negative electrode layer includes at least a negative electrode active layer.

[0448] In this application, unless otherwise stated, the negative electrode sheet includes at least a negative electrode active layer.

[0449] Unless otherwise stated in this application, the negative electrode active layer includes at least a negative electrode active material.

[0450] Non-limiting, the negative electrode active layer may include a solid electrolyte material. In this application, unless otherwise specified, the solid electrolyte material in the negative electrode active layer may be referred to as "negative electrode electrolyte material".

[0451] Non-limiting, the mass percentage content of the negative electrode active material in the negative electrode active layer can be ≥80%, and more preferably ≥90%. Non-limiting, the mass percentage content of the negative electrode active material in the negative electrode active layer can be 80% to 98%, optionally 90% to 98%, and more preferably 95% to 98%, and can also be any of the following percentages or a range selected from any two of the following percentages: 80%, 82%, 84%, 85%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, etc.

[0452] Non-limitingly, the mass percentage of the negative electrode electrolyte material in the negative electrode active layer can be 0% to 30%, preferably 0.1% to 30%, and further preferably 5% to 20%.

[0453] In some implementations, the negative electrode active material is a lithium indium alloy (InLi alloy).

[0454] In some embodiments, the negative electrode layer or negative electrode sheet is an InLi alloy film.

[0455] In some embodiments, the negative electrode active material may also be a negative electrode active material known in the art for use in solid-state batteries. As a non-limiting example, the negative electrode active material may include one or more of the following materials: elemental silicon, elemental tin, silicon-carbon composites, silicon suboxide, graphite, and metallic lithium. However, this application is not limited to these materials or substances, and other conventional materials that can be used as battery negative electrode active materials may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0456] In some embodiments, the negative electrode active material includes a silicon-based material, and more particularly, it can be a silicon-based material. Non-limitingly, the mass percentage of the silicon-based material in the negative electrode active layer can be 80% to 98%, optionally 90% to 98%, more preferably 95% to 98%, and can also be any of the following percentages or a range selected from any two of the following percentages: 80%, 82%, 84%, 85%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, etc.

[0457] In some embodiments, the negative electrode sheet may include a negative current collector and a negative active layer disposed on at least one surface of the negative current collector, the negative active layer comprising a negative active material. As a non-limiting example, the negative current collector has two surfaces opposite to each other in its own thickness direction, and the negative active layer is disposed on either or both of the two opposite surfaces of the negative current collector.

[0458] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. In the negative 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 negative electrode current collector, the composite current collector may be formed by forming a metal material on the polymer material substrate. Non-limiting examples of the metal material in the negative electrode current collector may include at least one of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. Non-limitingly, in the negative 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).

[0459] In some implementations, the negative electrode current collector is a composite copper-lithium sheet, which is composed of copper and lithium sheets.

[0460] In some embodiments, the negative electrode active layer optionally includes a conductive agent (which may be referred to as a negative electrode conductive agent). Non-limitingly, the negative electrode conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. Non-limitingly, the mass percentage of the negative electrode conductive agent in the negative electrode active layer may be 0–15%, more preferably 0–10%, and even more preferably 0–5%.

[0461] In some embodiments, the negative electrode active layer optionally includes an adhesive (denoted as negative electrode adhesive). As a non-limiting example, the negative electrode adhesive may include one or more of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS). Non-limitingly, the mass percentage of the negative electrode adhesive in the negative electrode active layer may be 0–10%, more further 1%–10% or 0–5%, even more further 1%–5%, and even more preferably 1%–3%.

[0462] In some embodiments, the negative electrode active layer may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)). The mass percentage of the other additives in the negative electrode active layer may be 0–15%, more preferably 0–10%, even more preferably 0–5%, even more preferably 0–3%, and even more preferably 0–2%.

[0463] In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as negative electrode active material, negative electrode conductive agent, negative electrode binder, and any other components, in a solvent to form a negative electrode slurry. Taking a negative electrode component including a sulfide solid electrolyte as an example, a non-limiting example of a solvent is p-xylene. Further, the negative electrode slurry is coated onto at least one surface of the negative electrode current collector, and after drying, cold pressing (optional), etc., the negative electrode sheet is obtained. Optional cold pressing can be performed using a cold rolling mill. The surface of the negative electrode current collector coated with the negative electrode slurry can be a single surface of the negative electrode current collector or both surfaces of the negative electrode current collector. The solid content of the negative electrode slurry can be 30wt% to 70wt%, optionally 40wt% to 60wt%. The viscosity of the negative electrode slurry at room temperature can be adjusted to 2000 mPa·s to 10000 mPa·s, optionally 3000 mPa·s to 10000 mPa·s. When coating the negative electrode slurry, the coating surface density on one side of the negative electrode current collector, based on dry weight (excluding solvent), can be, but is not limited to, 5 mg / cm³. 2 ~22mg / cm 2 However, it is not limited to this.

[0464] In solid-state batteries, the compaction density of the negative electrode layer can be, but is not limited to, 1.0 g / cm³. 3 ~2.0g / cm 3 1.0g / cm³ is an optional value. 3 ~1.8g / cm 3 .

[0465] In this application, unless otherwise stated, the compaction density of the negative electrode layer is equal to the ratio of the mass to the volume of the negative electrode layer.

[0466] The following is a description of the solid electrolyte layer.

[0467] A solid electrolyte layer can be introduced by forming electrode layers on both sides of the solid electrolyte membrane, or it can be introduced on the electrode layer.

[0468] The solid electrolyte layer acts as a conductor of ions between the positive and negative electrode layers, and can also isolate the positive and negative electrode layers to prevent short circuits between them.

[0469] 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.

[0470] 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.

[0471] As a non-limiting example, in different film layers of a solid-state battery, the solid electrolyte material may include one or more of the following: sulfide solid electrolyte, halide solid electrolyte, oxide solid electrolyte, polymer solid electrolyte, etc.

[0472] As another non-limiting example, in different film layers of a solid-state battery, the solid electrolyte material can be, but is not limited to, one or more of oxide-based solid electrolytes, sulfide-based solid electrolytes, and halide-based solid electrolytes. In some embodiments, the solid electrolyte material can independently include, but is not limited to, one or more of Argyrodite-type sulfide electrolytes and halide electrolytes. Non-limiting examples of oxide-based solid electrolytes may include LISICON-type oxide electrolytes (such as γ-Li3PO4), NASICON-type oxide electrolytes (such as Li... 1+x Al x Ge 2-x (PO4)3,Li 1+x Al x Ti 2-x(PO4)3, etc., 0≤x≤1), Garnet type (such as Li7La3Zr2O) 12 (etc.), perovskite-type oxide electrolytes (such as Li, etc.) 3x La 2 / 3-x One or more of the following: TiO3, etc., 0≤x≤0.5, etc. Non-limiting examples of sulfide solid electrolytes may include Li... 10 GeP2S 12 Li₂S-P₂S₅, Argyrodite type (such as Li₆PS₅Cl, Li 5.5 PS 5.5 Cl 1.5 One or more of the following, and may also include sulfide solid electrolytes as described in the context. Non-limiting examples of halide solid electrolytes may include one or more of the following: Li3InCl6, Li3YCl6, Li3ScCl6, Li3ErCl6, Li2ZrCl6, etc.

[0473] Solid electrolyte membranes or solid electrolyte layers can be prepared using dry methods. In some embodiments, the solid electrolyte layer can be formed by pressing solid electrolyte materials into a solid electrolyte membrane. In other embodiments, the solid electrolyte layer is formed by pressing the constituent raw materials of the solid electrolyte layer onto an electrode layer. In still other embodiments, the solid electrolyte membrane can also be prepared using methods such as fibrosis combined with calendering, melt extrusion, or spraying.

[0474] Solid electrolyte layers can also be prepared using a wet process. The electrolyte slurry used includes at least a solid electrolyte material and an organic solvent, and usually also includes one or more of a binder and a dispersant.

[0475] In some embodiments, the thickness of the solid electrolyte layer can be 0.1 μm to 1000 μm, and can be selected as 10 μm to 100 μm.

[0476] In a non-limiting manner, the positive electrode layer, the solid electrolyte layer, and the negative electrode layer can be assembled in a stacked manner, with the solid electrolyte layer placed between the positive electrode layer and the negative electrode layer.

[0477] Non-limitingly, a solid-state battery cell can be prepared by stacking a positive electrode, a solid electrolyte membrane, and a negative electrode in sequence, placing the solid electrolyte membrane between the positive and negative electrodes, and densifying the membrane.

[0478] 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.

[0479] 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.

[0480] 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 1 shows a square solid-state battery cell 5 as an example.

[0481] In some embodiments, referring to FIG2, 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.

[0482] Solid-state batteries can be battery device 4 or battery pack 1.

[0483] 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.

[0484] Figure 3 shows a battery device 4 as an example. Referring to Figure 3, 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.

[0485] 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.

[0486] 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.

[0487] Figures 4 and 5 show a battery pack 1 as an example. Referring to Figures 4 and 5, 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, 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.

[0488] In a second aspect of this application, a positive electrode active material is provided, which includes a coated oxide active material. The definition of a coated oxide active material can be found in the first aspect of this application.

[0489] In some embodiments, a positive electrode active material is provided, comprising a coated oxide-based active material. The coated oxide-based active material includes a positive electrode active body and a coating layer located on at least a portion of the surface of the positive electrode active body. The positive electrode active body comprises a lithium transition metal oxide, and the coating layer comprises a lithium metal halide oxide. In some embodiments, the coated oxide-based active material satisfies one or both of the following characteristics: (v1) ΔD ≤ 50 nm; (v2) R1 ≤ 0.5; wherein the definitions of ΔD and R1 are provided in the first aspect of this application.

[0490] By in-situ coating a non-solid metal halide with an oxide-based positive electrode active material containing lithium residual alkali, a lithium metal halide oxide with high ionic conductivity can be formed while maintaining a relatively uniform thickness distribution of the coating layer. Furthermore, the in-situ coating reaction consumes a significant amount of the residual alkali on the surface of the oxide-based positive electrode active material, further reducing the interfacial impedance of the positive electrode active material. Applying the prepared coated oxide-based active material to positive electrode sheets and solid-state batteries can significantly reduce the positive electrode interfacial impedance, significantly reduce positive electrode interfacial polarization caused by coating layer thickness fluctuations, effectively improve the solid-phase transport of positive electrode active ions, greatly promote positive electrode capacity utilization, and significantly improve the cycle performance of solid-state batteries. Moreover, the method is simple, highly controllable, easy to operate, and low in cost, making it suitable for large-scale production.

[0491] By introducing coated oxide-type active materials with high ionic conductivity and good coating uniformity into the positive electrode active material, the interface impedance of the positive electrode can be significantly reduced, which can significantly improve the coulombic efficiency of solid-state batteries.

[0492] In some embodiments, the positive electrode active material includes the characteristics of the positive electrode active material in the solid-state battery described in the first aspect of this application.

[0493] In other embodiments, a positive electrode active material is provided, which can be used as a raw material for preparing positive electrode active materials in solid-state batteries.

[0494] In some embodiments, the lithium transition metal oxide in the coated oxide active material includes lithium nickel-based oxide.

[0495] Without limitation, lithium transition metal oxides 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):

[0496] (j1) The atomic molar ratio of Ni to non-lithium metal in lithium nickel-based oxides is q1, where 0.5≤q1≤1;

[0497] (j2) Lithium nickel-based oxides contain Ni and Li elements in an atomic molar ratio of q2:x2, wherein 0.5≤q2≤1 and 0.9≤x2≤1.1;

[0498] (j3) Lithium nickel-based oxides contain Ni and O elements in an atomic molar ratio of q3:x3, wherein 0.5≤q3≤1 and 1.8≤x3≤2.1;

[0499] (j4) Lithium nickel-based oxides contain the element Co;

[0500] (j5) Lithium nickel-based oxides contain the element Mn;

[0501] (j6) Lithium nickel-based oxides have a layered crystal structure.

[0502] In some embodiments, the lithium transition metal oxide 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):

[0503] (z1)0.6≤q1≤1; optionally, 0.6≤q1≤0.96;

[0504] (z2)0.6≤q2≤1; optionally, 0.6≤q2≤0.96;

[0505] (z3)0.98≤x2≤1.02;

[0506] (z4)0.6≤q3≤1; optionally, 0.6≤q3≤0.96;

[0507] (z5)1.96≤x3≤2.04;

[0508] (z6) The lithium nickel-based oxide contains the element Co, and the atomic molar ratio of the element Co to the non-lithium metal elements in the lithium nickel-based oxide is q4, where 0.02≤q4≤0.35;

[0509] (z7) The lithium nickel-based oxide contains the element Mn, and the atomic molar ratio of the element Mn to the non-lithium metal elements in the lithium nickel-based oxide is q5, where 0.01≤q5≤0.38;

[0510] (z8) The mass percentage of lithium nickel-based oxides in lithium transition metal oxides is 80% to 100%.

[0511] In some embodiments, the lithium transition metal oxide 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):

[0512] (z1')0.5≤q1≤0.99; optionally, 0.5≤q1≤0.9; optionally, 0.5≤q1≤0.8;

[0513] (z2')0.5≤q2≤0.99; optionally, 0.5≤q2≤0.9; optionally, 0.5≤q2≤0.8;

[0514] (z3')0.99≤x2≤1.01;

[0515] (z4')0.5≤q3≤0.99; optionally, 0.5≤q3≤0.9; optionally, 0.5≤q3≤0.8;

[0516] (z5')1.98≤x3≤2.02;

[0517] (z6') Lithium nickel-based oxides contain Co, with 0.05 ≤ q4 ≤ 0.25;

[0518] (z7') Lithium nickel-based oxides contain Mn element, 0.02≤q5≤0.38;

[0519] (z8') The mass percentage of lithium nickel-based oxides in lithium transition metal oxides is 90%–100%;

[0520] (z9') Lithium transition metal oxides include lithium nickel cobalt manganese-based oxides.

[0521] Without limitation, the definitions of q1, q2, q3, q4, and q5 can also be found in the first aspect of this application.

[0522] In some implementations, x2 is 0.9 to 1.1, optionally 0.95 to 1.05, further optionally 0.98 to 1.02, and even further optionally 0.99 to 1.01. It can also be any of the following values ​​or a range selected from any two of the following values: 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.08, 1.1, etc.

[0523] In some implementations, x3 is 1.96 to 2.04, can be 1.098 to 2.02, or can be any of the following values ​​or a range selected from any two of the following values: 1.96, 1.97, 1.98, 1.99, 2, 2.01, 2.02, 2.03, 2.04, etc.

[0524] In some embodiments, the positive electrode active 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):

[0525] (g1) Lithium transition metal oxides include lithium nickel cobalt manganese-based oxides; in lithium nickel cobalt manganese-based oxides, the ratio of the sum of the atomic molar ratios of nickel, cobalt, and manganese to the sum of the atomic molar ratios of non-lithium metal elements is denoted as R. NCM R NCM The value is 0.9 to 1; optionally, R NCM The value is 0.95 to 1; see also the first aspect of this application.

[0526] (g2) The mass percentage of the coated oxide active material in the positive electrode active material is 80% to 100%, and can be selected as 90% to 100%. See also the first aspect of this application.

[0527] (g3) The ionic conductivity of lithium metal halide oxide at 25°C is greater than or equal to 1 mS / cm, and can be selected from 1 mS / cm to 10 mS / cm. See also the first aspect of this application.

[0528] (g4) The ionic conductivity of the positive electrode active material at 25°C is greater than or equal to 0.01 mS / cm. See also the first aspect of this application.

[0529] (g5) The ionic conductivity of the coated oxide active material at 25°C is greater than or equal to 0.01 mS / cm. See also the first aspect of this application.

[0530] In another aspect of this application, a coated oxide-based active material is provided, which may be the coated oxide-based active material described in the second aspect of this application.

[0531] In a third aspect of this application, a method for preparing a coated oxide-based active material is provided, which can be used to prepare the coated oxide-based active material described in the second aspect of this application.

[0532] In some embodiments, a method for preparing a coated oxide-based active material is provided, comprising the following steps:

[0533] S100: Provides an oxide-based positive electrode active material; wherein, the oxide-based positive electrode active material includes a positive electrode active body and a lithium-containing residual alkali located on at least a portion of the surface of the positive electrode active body, and the positive electrode active body includes a lithium transition metal oxide;

[0534] S200: Under selected atmosphere and heating conditions, an oxide-based positive electrode active material is subjected to an in-situ coating reaction with a non-solid metal halide, so that the lithium-containing residual alkali reacts with the non-solid metal halide to form lithium metal halide oxide. After cooling, a coated oxide-based active material is obtained. The selected atmosphere is a vacuum or an inert gas atmosphere, and the metal element in the non-solid metal halide is a non-lithium metal element.

[0535] For a definition of coated oxide-based active materials, please refer to the second aspect of this application.

[0536] By in-situ coating a non-solid metal halide with an oxide-based positive electrode active material containing lithium residual alkali, a lithium metal halide oxide with high ionic conductivity can be formed while controlling the coating layer to have a relatively uniform thickness distribution. Applying the prepared coated oxide-based active material to positive electrode sheets and solid-state batteries can significantly reduce the positive electrode interface impedance, significantly reduce the positive electrode interface polarization caused by coating layer thickness fluctuations, effectively improve the solid-phase transport of positive electrode active ions, greatly promote the positive electrode capacity, and significantly improve the cycle performance of solid-state batteries.

[0537] Compared to methods that involve physically mixing oxide-based active materials with prepared metal halide oxides (such as through ball milling) to achieve coating, the aforementioned in-situ coating reaction method produces a coating layer with better uniformity and a more uniform coating thickness.

[0538] In addition, coated oxide active materials have high ionic conductivity and good coating uniformity. By introducing such coated oxide active materials into the cathode layer, the cathode interface impedance can be significantly reduced, and the coulombic efficiency of solid-state batteries can be significantly improved.

[0539] In step S100, the oxide-based positive electrode active material can be commercially available or prepared by the following method: under an oxygen-containing atmosphere, a mixture including the positive electrode active material precursor and the lithium source is sintered to prepare the oxide-based positive electrode active material.

[0540] In some embodiments, the positive electrode active material precursor is prepared by a method including the following step S10:

[0541] S10: Under alkaline conditions (such as in the presence of ammonia), a co-precipitation reaction is carried out on raw materials including transition metal salts and alkali metal hydroxides to prepare a precursor for the positive electrode active material; wherein the precursor for the positive electrode active material includes lithium transition metal oxides. The composition of the precursor for the positive electrode active material can be determined using instruments such as the Pekin Elmer Optima 5300DV, but is not limited to these.

[0542] In step S10, it is understood that the transition metal salt is a soluble salt in the reaction system undergoing the co-precipitation reaction. Non-limiting examples of transition metal salts may include, but are not limited to, sulfates. Non-limiting examples of alkaline lithium sources include lithium hydroxide. Taking the preparation of lithium nickel cobalt manganese oxide as an example, the transition metal salt can be a combination of nickel, cobalt, and manganese salts.

[0543] In some embodiments, the solvent in the reaction system in which the coprecipitation reaction takes place is water.

[0544] In some embodiments, the pH for the co-precipitation reaction can be controlled by ammonia and alkaline oxygenates of alkali metals (such as alkali metal hydroxides, alkali metal carbonates, etc.). The residual alkali content on the surface of the oxide-based cathode active material can be controlled by adjusting the amount of alkaline oxygenate used. In some embodiments, the alkaline oxygenate of the alkali metal is in excess relative to the theoretical yield of the cathode active material precursor, such as an excess of 2wt% to 5wt%. Non-limiting examples of alkaline oxygenates of alkali metals may include LiOH, Li₂CO₃, etc.

[0545] The amount of residual lithium alkali on the surface can be determined using methods already available in the art, such as, but not limited to, electrochemical titration.

[0546] In some embodiments, in the step of sintering the mixture comprising the positive electrode active material precursor and the lithium source, the sintering temperature is 600°C to 1000°C, and optionally, the sintering time is 4h to 8h.

[0547] In some embodiments, the preparation method of the coated oxide-based active 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):

[0548] (h1) Non-solid metal halide salts are one or both of gaseous and liquid states;

[0549] (h2) The melting point of the non-solid metal halide is 120℃~400℃, optionally 150℃~350℃, and further optionally 180℃~300℃;

[0550] (h3) The boiling point of the non-solid metal halide is 120℃~400℃, preferably 150℃~350℃, and further preferably 180℃~300℃;

[0551] (h4) The temperature for the in-situ coating reaction is 120℃~400℃, optionally 150℃~350℃, and further optionally 180℃~300℃; optionally, the reaction time is 2h~6h;

[0552] (h5) The metal elements in non-solid metal halide salts include one or more of Zr, Ta, Nb, In, W, Ge, Ga, Sb, Sn, Al and Ti;

[0553] (h6) The halogens in non-solid metal halide salts include one or more of F, Cl, Br and I.

[0554] In some embodiments, the non-solid metal halide is one or both of gaseous and liquid states.

[0555] In some implementations, the non-solid metal halide is in a gaseous state.

[0556] In some embodiments, the melting point (T2) and boiling point (T3) of the non-solid metal halide can each be independently 120°C to 400°C, optionally 150°C to 350°C, further optionally 180°C to 300°C, or a range consisting of any two of the following temperatures: 120°C, 130°C, 140°C, 150°C, 160°C, 180°C, 200°C, 220°C, 240°C, 250°C, 260°C, 280°C, 300°C, 320°C, 340°C, 350°C, 360°C, 380°C, 400°C, etc.

[0557] In some embodiments, the temperature (T4) for carrying out the in-situ coating reaction can be 120°C to 400°C, optionally 150°C to 350°C, further optionally 180°C to 300°C, or a range consisting of any two of the following temperatures: 120°C, 130°C, 140°C, 150°C, 160°C, 180°C, 200°C, 220°C, 240°C, 250°C, 260°C, 280°C, 300°C, 320°C, 340°C, 350°C, 360°C, 380°C, 400°C, etc.

[0558] In a non-limiting sense, the reaction time for the in-situ coating reaction can be 2h to 6h, such as 2h, 3h, 4h, 5h, 6h, etc., or any of the aforementioned durations or a range selected from any two of the aforementioned durations.

[0559] In step S200, the setup used for the in-situ coating reaction can be a tube furnace. The selected atmosphere can be a vacuum condition or an inert gas atmosphere; non-limiting examples of inert gas atmospheres include helium, neon, nitrogen, and argon. In-situ sintering in an inert atmosphere within a tube furnace is more conducive to achieving adjustable surface coating thickness and coating uniformity. Sintering under vacuum conditions in a tube furnace or other temperature-controlled heat treatment methods under an inert atmosphere, such as a muffle furnace, can also be used to achieve the same or similar effects.

[0560] Without limitation, the metal element in the non-solid metal halide may include one or more of Zr, Ta, Nb, In, W, Ge, Ga, Sb, Sn, Al, and Ti.

[0561] Without limitation, the halogen in the non-solid metal halide may include one or more of F, Cl, Br and I, and may further include one or two of F and Cl, and even further may be selected from one or two of F and Cl.

[0562] Non-limiting examples of metal halide salts may include one or more of ZrF4, ZrCl4, TaCl5, TaF5, NbCl5, NbF5, WCl6, InCl3, InF3, AlF3, AlCl3, GaF3, and GaCl3.

[0563] In some embodiments, the metal halide includes one or more of ZrCl4, TaCl5, NbCl5, ZrF4, NbF5, WCl6, AlCl3, and InCl3.

[0564] By selecting the aforementioned types of non-solid metal halide salts, in-situ coating reactions can be carried out between gaseous and / or liquid M halides and the surface residual alkali of lithium transition metal oxides at relatively low temperatures (such as 120℃~400℃), far below the sintering temperature of the positive electrode active material, thereby forming a coating layer with high ionic conductivity and relatively uniform coating thickness.

[0565] In step S200, the cooling rate can be 1°C / min to 3°C / min, but is not limited to this. A suitable cooling rate is beneficial for improving the uniformity of the coating layer. In some embodiments, cooling is performed to room temperature.

[0566] In some embodiments, the preparation method of the coated oxide-based active 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):

[0567] (k1) Non-solid metallic halides are in the gaseous state;

[0568] (k2) Lithium transition metal oxides include one or more of lithium nickel-based oxides, lithium-rich manganese-based cathode active materials, spinel lithium manganese oxide and lithium cobalt oxide, and may also be referred to the first aspect of this application;

[0569] (k3) Lithium-containing residual alkali includes one or more of lithium carbonate and lithium hydroxide;

[0570] (k4) In oxide-based positive electrode active materials, the mass percentage of lithium residual alkali is 0.5% to 2%;

[0571] (k5) The initial ratio of oxide-based positive electrode active material to non-solid metal halide salt in terms of feed amount is (30-50):1;

[0572] (k6) Based on the amount of material fed, the atomic molar ratio of halogen in non-solid metal halide salts to oxygen in oxide-type positive electrode active materials is (1-4):(0.8-1.2), which can be selected as 1-5, and further selected as 2-5;

[0573] (k7) The ionic conductivity of lithium metal halide oxides at 25°C is 1 mS / cm to 10 mS / cm, and see also the first aspect of this application;

[0574] (k8) The ionic conductivity of the coated oxide active material at 25℃ is greater than or equal to 0.01 mS / cm. See also the first aspect of this application.

[0575] (k9) The obtained coated oxide active material includes the characteristics of the coated oxide active material in the positive electrode active material described in the second aspect of this application.

[0576] In some embodiments, in step S100, the sintering temperature is 600℃ to 1000℃, and optionally, the sintering time is 4h to 8h. The sintering temperature can also be any of the following temperatures or a range selected from any two of the following temperatures: 600℃, 650℃, 700℃, 750℃, 800℃, 850℃, 900℃, 950℃, 1000℃, etc. The sintering time can be 4h to 8h, such as 4h, 5h, 6h, 7h, 8h, etc., and can also be any of the aforementioned durations or a range selected from any two of the aforementioned durations.

[0577] In some embodiments, the lithium-containing residual alkali includes one or more of lithium carbonate and lithium hydroxide.

[0578] Non-limitingly, in oxide-based positive electrode active materials, the mass percentage of lithium residual alkali can be 0.5% to 2%, and can also be any of the following percentages or a range selected from any two of the following percentages: 0.5%, 0.6%, 0.8%, 1%, 1.2%, 1.4%, 1.5%, 1.6%, 1.8%, 2%, etc.

[0579] Non-limitingly, the initial ratio of oxide-based positive electrode active material to non-solid metal halide salt, based on the amount of material fed, can be (30-50):1, or any of the following ratios or a range selected from any two of the following ratios: 30:1, 32:1, 34:1, 35:1, 36:1, 38:1, 40:1, 42:1, 44:1, 45:1, 46:1, 48:1, 50:1, etc.

[0580] Non-limitingly, based on the amount of material fed, the atomic molar ratio of halogen in the non-solid metal halide to oxygen in the oxide-based positive electrode active material can be (1-4):(0.8-1.2), optionally 1-5, further optionally 2-5, and can also be any of the following ratios or a range selected from any two of the following ratios: 1:1, 1.1:1, 1.2:1, 1.25:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7 :1, 1.75:1, 1.8:1, 2:1, 2.1:1, 2.2:1, 2.25:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.75:1, 2.8:1, 3:1, 3.2:1, 3.25:1, 3.4:1, 3.5:1, 3.6:1, 3.8:1, 4:1, 4.25:1, 4.5:1, 4.6:1, 4.75:1, 4.8:1, 5:1, etc.

[0581] In a fourth aspect of this application, a positive electrode sheet is provided, which includes a positive active layer. The positive active layer includes at least one of the positive active materials described in the second aspect of this application and the coated oxide active materials prepared by the preparation method of the coated oxide active materials described in the third aspect of this application, or the positive active layer includes the characteristics of the positive active layer in the solid-state battery described in the first aspect of this application.

[0582] In a fifth aspect of this application, an electrical device is provided, comprising at least one of the following: a solid-state battery as described in the first aspect of this application, a positive electrode active material as described in the second aspect of this application, a coated oxide active material prepared by the method for preparing coated oxide active materials as described in the third aspect of this application, and a positive electrode sheet as described in the fourth aspect of this application.

[0583] In some embodiments, the electrical device includes at least one of the solid-state batteries of any of the embodiments provided in this application.

[0584] 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.

[0585] As an electrical device, solid-state batteries can be selected based on its usage requirements.

[0586] Figure 6 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.

[0587] 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.

[0588] The following describes some embodiments of this application. The described embodiments are only a part of the embodiments of this application, and not all of them. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application and its applications. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0589] Unless otherwise specified in the examples, the procedures described above, or those described in the literature in this field, or those described in the product instructions, shall be followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products, or products that can be synthesized using conventional methods from commercially available products.

[0590] In the following examples, room temperature refers to 20°C to 30°C.

[0591] 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.

[0592] In the following examples, unless otherwise specified, the use of organic solvents to disperse sulfide 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.

[0593] 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.

[0594] In the following examples, unless otherwise specified, the parameters involved can be confirmed and / or adjusted using the test methods described above. For example, parameters involving ionic conductivity, D... v 50. Coating layer related parameters (ΔD, D1, R1, F) A Tests were conducted on the melting and boiling points of M halides, the chemical composition of lithium metal halide oxides, and the material composition of the positive electrode active layer.

[0595] I. Preparation of coated oxide active materials and all-solid-state lithium-ion secondary batteries.

[0596] In the following examples, the prepared coated oxide-based active materials can be labeled LMOX@Cathode, where LMOX represents lithium metal halide oxide, L corresponds to the element Li, M corresponds to the non-lithium metal element, O corresponds to the element oxygen, X corresponds to the halogen element, and Cathode corresponds to the type of positive electrode active material. It should be noted that LMOX only refers to the elemental types in the lithium metal halide oxide and does not indicate the atomic molar ratio of each element.

[0597] Example 1.

[0598] (1) Preparation of coated oxide-based active materials (second sintering)

[0599] The surface includes an oxide-based positive electrode active material containing lithium residual alkali (denoted as NCM). 811 The material is mixed with the metal halide at a mass ratio of (30-50):1, weighed and placed in a mortar. After grinding for 10-30 minutes, it is transferred to a tube furnace through an alumina ceramic boat. The atmosphere is replaced several times with inert gas, and sintered at a temperature of T4 for 2-5 hours. After cooling to room temperature, the coated oxide active material can be obtained.

[0600] In this example, the positive electrode active material is NCM. 811 (LiNi 0.8 Co 0.1 Mn 0.1 O2), and the mass percentage of lithium-containing residual alkali in oxide-based positive electrode active materials is approximately 4 wt%.

[0601] In Example 1, the metallic halide was a chloride of Ta (TaCl5), with a melting point of approximately 216°C and a boiling point of approximately 239.4°C. A suitable sintering temperature was selected based on the melting and boiling points of the metallic halide to maintain it in a gaseous and / or liquid state, preferably in a gaseous state. Argon was used as the inert gas. In Example 1, the sintering temperature T4 was 220°C, the sintering time was 2 hours, and the cooling rate was controlled within the range of 1°C / min to 3°C / min. Some parameters can be found in Table 1.

[0602] The lithium metal halide oxide on the surface of the prepared coated oxide active material can be denoted as LTaOCl.

[0603] The coated oxide-based active material in Example 1 can be designated as LTaOCl@NCM 811 .

[0604] (2) Assemble all-solid-state lithium-ion secondary batteries.

[0605] Coated oxide-based active materials are used as positive electrode active materials.

[0606] Conductive agent (carbon black Super P), positive electrode electrolyte material (sulfide solid electrolyte Li) 7-y PS5Cl y In this example, y = 1) and coated oxide active materials are mixed in a mass ratio of 1:(5~8):(40~45) (total weight is several grams (g)) and ground for 10 min to 30 min to obtain composite cathode powder.

[0607] 80mg to 130mg (100mg in this example) of sulfide solid electrolyte Li6PS5Cl was weakly pressed into a sheet at 1MPa to 2MPa to obtain a solid electrolyte membrane. Indium sheet and composite copper-lithium sheet (lithium side facing the solid electrolyte layer) were added sequentially on the other side. Then, about 15mg to 25mg (20mg in this example) of composite cathode powder was added on the other side of the solid electrolyte membrane. The pressure was increased to 20MPa to 50MPa and held for several minutes. Then, the battery performance was tested.

[0608] In this example, the conductive agent, positive electrode electrolyte material, and coated oxide active material are in a mass ratio of 1:5:44, which corresponds to 2:10:88.

[0609] Examples 2-6 use the same method as Example 1 to prepare coated oxide active materials and all-solid-state lithium-ion secondary batteries. The difference is that different types of metal halide salts are used in the step of preparing coated oxide active materials, and different coated oxide active materials are used to assemble all-solid-state lithium-ion secondary batteries. The remaining operation steps are the same as in Example 1.

[0610] The metal halide salts used in Examples 2-7 are NbCl5, TaF5, NbF5, AlCl3, and InCl3, respectively. See Table 1 for details.

[0611] Example 7 uses the same method as Example 1 to prepare coated oxide active materials and all-solid-state lithium-ion secondary batteries. The difference is that the prepared coated oxide active materials are different, the chemical composition of the positive electrode active body has different nickel content, the average thickness of the coating layer is basically the same as that of Example 1, and the all-solid-state lithium-ion secondary batteries are assembled using different coated oxide active materials. The remaining operation steps are the same as those in Example 1.

[0612] In Example 7, the positive electrode active material prepared was NCM. 622 (LiNi 0.6 Co 0.2 Mn 0.2 O2).

[0613] Example 8 uses the same coated oxide active material as Example 1 as the positive electrode active material; an all-solid-state lithium-ion secondary battery is prepared using a method basically the same as in Example 1, the difference being that the component ratios in the positive electrode composite powder are different, and the conductive agent (carbon black Super P) and the positive electrode electrolyte material (sulfide solid electrolyte Li) are different. 7-y PS5Cl y The mass ratio of the active material (y=1) and the coated oxide active material is 2:14.5:83.5, and the remaining operation steps are the same as in Example 1.

[0614] Comparative Example 1 used essentially the same method as Example 1 to prepare an all-solid-state lithium-ion secondary battery, the difference being that the positive electrode active material was coated with a different substance; the positive electrode active material was Li3PO4@NCM. 811 Different positive electrode active materials were used to assemble all-solid-state lithium-ion secondary batteries, and the remaining operation steps were the same as in Example 1.

[0615] Preparation of Li3PO4@NCM 811 The steps are as follows: NCM cathode material 811 (D v 50 approximately 5 μm, the same NCM as in Example 1 811 The material was placed in the ALD (Atomic Layer Deposition) deposition chamber reactor, and the total mass of NCM was... 811 The precursors A (trimethyl phosphate) and B (lithium tert-butoxide) in 0.5 wt% by mass of the material are volatilized at a controlled temperature in a molar ratio of 1:3, and an in-situ coating layer is formed.

[0616] Comparative Example 2 uses the same method as Example 1 to prepare coated oxide active materials and all-solid-state lithium-ion secondary batteries. The difference is that in the step of preparing coated oxide active materials, the sintering temperature T4 is adjusted to 600°C, and different positive electrode active materials are used to assemble all-solid-state lithium-ion secondary batteries. The remaining operation steps are the same as in Example 1.

[0617] Comparative Example 3 uses a physical blending method to prepare a positive electrode active material with a lithium metal halide oxide layer on the surface. Different positive electrode active materials are used to assemble an all-solid-state lithium-ion secondary battery. The remaining operation steps are the same as in Example 1.

[0618] (1) LiTaOCl4 was prepared by the following method: 5g of LiOH and TaCl5 were added to a 250mL vacuum zirconia ball mill jar at a molar ratio of 1:1. 100-200g of 5mm diameter zirconia beads were added, and the mixture was ball-milled at 600rpm for 30h. The zirconia beads were then separated by sieving to obtain LiTaOCl4 powder. v 50 is 2.3nm.

[0619] (2) LiTaOCl4 was coated onto NCM using a physical blending method. 811 Surface: according to NCM 811 The same materials (as in Example 1) and LiTaOCl4 powder were added to a mixer at a mass ratio of 45:1. Ten times the mass ratio (compared to the powder) of balls were added, and the mixture was stirred at 300 rpm for half an hour. NCM 811 The raw materials are the same as in Example 1. LiTaOCl4 powder and NCM 811 The mass ratio of the raw materials is approximately 2%, which is similar to that of Example 1.

[0620] Comparative Example 4 uses the same method as Example 8 for a fully solid-state lithium-ion secondary battery. The difference is that the positive electrode active material is the same as in Comparative Example 3, but a different positive electrode active material is used to assemble the fully solid-state lithium-ion secondary battery. The remaining operation steps are the same as in Example 8.

[0621] In Comparative Example 4, LTaOCl@NCM was prepared by physical blending. 811 The mass percentage of sulfide solid electrolyte in the positive electrode active layer is 14.5%.

[0622] Comparative Example 5 uses essentially the same method as Example 1 for an all-solid-state lithium-ion secondary battery, the difference being that the NCM without a coating layer from Example 1 is used instead. 811 The material is used as the positive electrode active material. Different positive electrode active materials are used to assemble all-solid-state lithium-ion secondary batteries. The remaining operation steps are the same as in Example 1.

[0623] Comparative Example 6 uses a method that is basically the same as that in Example 8 for a fully solid-state lithium-ion secondary battery. The difference is that the positive electrode active material is the same as in Comparative Example 5, but a different positive electrode active material is used to assemble the fully solid-state lithium-ion secondary battery. The other operation steps are the same as in Example 8.

[0624] In Comparative Example 6, the NCM without the coating layer from Example 1 was used. 811 As the positive electrode active material, the sulfide solid electrolyte in the positive electrode active layer has a mass percentage of 14.5%.

[0625] The relevant parameters for preparing the coated oxide active materials in Examples 1-8 and Comparative Examples 1-6 can be found in Table 1. The relevant parameters for the positive electrode active layer can also be found in Table 1.

[0626] II. Test and Analysis Methods

[0627] 1. Characterization of the structure and coating layer of coated oxide-based active materials

[0628] Instruments: Talos L120C TEM or Talos F200X.

[0629] Parameters: Average thickness of the coating layer (D1), difference between the maximum and minimum thickness of the coating layer (ΔD), percentage of the coating layer's coverage area relative to the positive electrode active body (F). A The mass percentage of lithium metal halide oxides in the coating layer (F) X1 The mass percentage of lithium metal halide oxides in coated oxide-based active materials (F) X0 ) Calculate R1 = ΔD / D1 according to the formula.

[0630] Refer to the testing methods described above.

[0631] 2. Ionic conductivity testing of coated oxide-based active materials

[0632] The conductive agent (carbon black Super P), the positive electrode electrolyte material (sulfide solid electrolyte Li6PS5Cl), and the coated oxide active material were mixed according to the mass ratio in Example 1 to obtain a composite positive electrode powder.

[0633] Test temperature: 25℃.

[0634] 100 mg of composite cathode powder was pressed into a mold at 10 MPa to obtain the test film. Then, sulfide solid electrolyte Li6PS5Cl was added to both sides of the test film, and it was pressed twice at 10 MPa. Subsequently, indium sheets and composite copper-lithium sheets were added to the outer sides, respectively. The resulting test system consisted of, in sequence, an indium layer, a sulfide solid electrolyte Li6PS5Cl layer, a cathode layer (composed of composite cathode powder), a sulfide solid electrolyte Li6PS5Cl layer, and a composite copper-lithium sheet (lithium side facing the sulfide solid electrolyte Li6PS5Cl layer). The test system was connected to an electrochemical workstation with a bias voltage of 10 mV and a frequency range of 10... 6 Hz to 10 -2 Electrochemical impedance spectroscopy (EIS) was performed in the Hz range, and the ionic conductivity was calculated based on the impedance value and the thickness of the positive electrode layer.

[0635] The resistance value R is recorded as the intersection of the curve from high frequency to low frequency with the Z' axis in the electrochemical impedance spectroscopy. The ionic conductivity of the membrane under test can be calculated using formula (1).

[0636] Where d is the thickness of the membrane to be tested, and A is the contact area between the membrane to be tested and the sulfide solid electrolyte Li6PS5Cl layer.

[0637] The test results can be found in Table 3, “Ionic Conductivity at 25℃”.

[0638] See also the description above.

[0639] 3. Battery performance test

[0640] (1) Battery internal resistance DCR test

[0641] At 25℃, the battery under test was charged to 4.3V at a constant current of 1 / 3C, then charged to a cutoff current of 0.05C at a constant voltage of 4.3V, allowed to stand for 30 minutes, and then discharged at a constant current of 1 / 3C for 0.5 hours, allowed to stand for 30 minutes, and the voltage V1 after standing was recorded. Subsequently, it was discharged at 1C for 30 seconds with a sampling interval of 0.1 seconds, and the voltage V2 at the end of the discharge was recorded.

[0642] The DCR of the battery under test is (V1-V2) / I, where I is the current corresponding to a 1C rate.

[0643] The test result was recorded as "Battery DCR".

[0644] (2) Discharge capacity, initial coulombic efficiency, and battery cycle performance tests

[0645] The operating voltage range of the battery under test was set to 2.6V to 4.3V. A constant current charge-discharge cycle test was conducted to obtain the initial discharge capacity, initial coulombic efficiency, and capacity retention rate after a certain number of cycles. The test current was 0.1C (current density 0.5mA / cm²). 2) The test temperature was 60℃.

[0646] At 60℃, the battery under test was charged to 4.3V at a constant current of 0.1C, rested for 10 minutes, and then discharged to 2.6V at a constant current of 0.1C, rested 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 cycles is recorded. The capacity retention rate P after 50 and 100 cycles is also recorded. 50 =C50 / C0×100%, P 100 =C100 / C0×100%.

[0647] 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.

[0648] The initial coulombic efficiency of the battery under test can be obtained by dividing the initial discharge capacity obtained from the test at 0.1C by the initial charge capacity.

[0649] The test results were recorded as “first-cycle discharge capacity”, “first-cycle coulombic efficiency”, “capacity retention rate after 50 cycles”, and “capacity retention rate after 100 cycles”.

[0650] III. Test Analysis Results

[0651] The coated oxide-based active materials prepared in Examples 1-8 exhibited excellent coating uniformity. In Examples 1-8, the difference between the maximum and minimum thickness of the coating layer (ΔD) was ≤50 nm; the percentage of the coating layer's coverage area relative to the positive electrode active body (F...)... A All parameters meet the requirement of ≥90%; the average thickness (D1) of the coating layer meets the requirement of ≥10nm, and further falls within the range of 20nm to 60nm; R1 (R1=ΔD / D1) is within the range of ≤0.3. Furthermore, in each of Examples 1-8, the mass percentage F of lithium metal halide in the coating layer is... X1 The mass percentage (F) of lithium metal halide oxides in coated oxide-based active materials is all within the range of 90% to 100%. X0 All were within the range of 0.2% to 2%.

[0652] Taking Example 1 as an example, ΔD is approximately 5 nm, F AApproximately 96%, D1 is approximately 30nm, R1 is approximately 0.17, F X1 Approximately 94%, F X0 Approximately 1.6%. The main component of the coating layer is LiTaOCl4, with a small amount of LiTaO3 also present. See Table 2 and Figure 8-11.

[0653] The coated oxide active materials prepared in each of Examples 1-8 all have high ionic conductivity, as shown in Table 3.

[0654] Compared with Comparative Examples 1-3 and 5, the all-solid-state lithium-ion secondary batteries prepared in Examples 1-7 and the all-solid-state lithium-ion secondary batteries prepared in Example 8 compared with Comparative Examples 4 and 6 all showed significantly improved cycle performance. The capacity retention rates after 50 and 100 cycles were significantly higher than those of the corresponding comparative examples.

[0655] Furthermore, the all-solid-state lithium-ion secondary batteries prepared in Examples 1-8 all exhibited significantly improved first-cycle discharge specific capacity and first-cycle coulombic efficiency, indicating that there were fewer side reactions during the first-cycle reaction, which kinetically favored lithium-ion transport. See Tables 3 and 4 for further details.

[0656] Taking Example 1 as an example, the first charge-discharge curve of the solid-state battery is shown in Figure 7.

[0657] The all-solid-state lithium-ion secondary batteries prepared in Examples 1-8 also exhibit significantly reduced DCR.

[0658] The coating material used in Comparative Example 1 is not a lithium metal halide oxide. Taking Example 1 as an example, the ionic conductivity of the coated oxide active material is an order of magnitude higher than that of Li3PO4 in Comparative Example 1.

[0659] The sintering temperature used in Comparative Example 2 was too high, which caused the metal halide to volatilize rapidly and fail to form an effective coating layer (see Table 2). The electrical properties were significantly degraded (see Table 3).

[0660] Comparative Example 3 used a physical blending method to coat the prepared lithium metal halide oxide onto the surface of the positive electrode active body. The coating uniformity was poor (see Table 2). The specific capacity of the first discharge cycle, the initial coulombic efficiency, and the capacity retention rate after 50 and 100 cycles were all significantly lower than those of the previous example.

[0661] Example 1 (see Table 3). Although Comparative Example 4 used a higher amount of solid electrolyte material, its capacity retention after 50 and 100 cycles was still lower than that of Example 1.

[0662] Comparative Example 5, which lacks a coating layer, exhibits significantly lower first-cycle discharge specific capacity, initial coulombic efficiency, and capacity retention after 50 and 100 cycles compared to Example 1 (see Table 3). Although Comparative Example 6 utilizes a higher amount of solid electrolyte material, its first-cycle discharge specific capacity, initial coulombic efficiency, and capacity retention after 50 and 100 cycles are still significantly lower than those of Example 8.

[0663] Table 1.

[0664] Table 2.

[0665] Table 3.

[0666] 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.

[0667] 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

1. A solid-state battery, comprising a positive electrode layer, a solid electrolyte layer, and a negative electrode layer sequentially stacked, wherein, The positive electrode layer includes a positive electrode active layer, which includes a positive electrode active material and a solid electrolyte material. The positive electrode active material includes a coated oxide active material, which includes a positive electrode active body and a coating layer located on at least a portion of the surface of the positive electrode active body. The positive electrode active body includes a lithium transition metal oxide, and the coating layer includes a lithium metal halide oxide. The difference between the maximum and minimum thickness of the coating layer in the coated oxide active material is denoted as ΔD, the average thickness of the coating layer in the coated oxide active material is denoted as D1, and the ratio of ΔD to D1 is denoted as R1. The coated oxide-based active material satisfies one or two of the following characteristics: (v1)ΔD≤50nm; (v2)R1≤0.

5.

2. The solid-state battery according to claim 1, wherein, The percentage of the coverage area of ​​the coating layer relative to the positive electrode active body in the coated oxide active material is denoted as F. A ; The coated oxide-based active material satisfies one or more of the following characteristics: (a1) ΔD ≤ 30nm; (a2) R1 is 0 to 0.3; (a3)F A ≥80%。 3. The solid-state battery according to claim 2, wherein, The coated oxide-based active material satisfies one or more of the following characteristics: (a1')ΔD≤15nm; (a2')R1 is 0 to 0.25; (a3')F A It ranges from 80% to 100%.

4. The solid-state battery according to claim 3, wherein, The coated oxide-based active material satisfies one or more of the following characteristics: (a1”)ΔD≤10nm; (a2')R1 is 0 to 0.2; (a3”)F A It is 95% to 100%.

5. The solid-state battery according to any one of claims 1 to 4, wherein, The average thickness of the coating layer in the coated oxide-based active material is denoted as D1, and the coated oxide-based active material satisfies one or more of the following characteristics: (b1) D1 is 10nm~100nm; (b2) The thickness of at least a portion of the coating layer is greater than or equal to 10 nm, optionally 10 nm to 100 nm, and further optionally 10 nm to 80 nm; (b3) In the coated oxide active material, the lithium metal halide oxide accounts for 70% to 100% of the mass of the coating layer; (b4) The lithium metal halide oxide accounts for 0.2% to 2% of the mass of the coated oxide active material.

6. The solid-state battery according to claim 5, wherein, The coated oxide-based active material satisfies one or more of the following characteristics: (b1')D1 is 20nm~60nm; (b2') At least a portion of the coating layer has a thickness of 20 nm to 50 nm; (b3') In the coated oxide active material, the lithium metal halide oxide accounts for 90% to 100% of the mass of the coating layer; (b4') The lithium metal halide oxide accounts for 0.5% to 2% of the mass of the coated oxide active material.

7. The solid-state battery according to any one of claims 1 to 6, wherein, The lithium metal halide oxide includes lithium, non-lithium metal elements, halogens, and oxygen; the halide formed by the non-lithium metal elements and halogens in the lithium metal halide oxide is denoted as M halide, and the M halide satisfies one or more of the following characteristics: (c1) The M halide is in a gaseous or liquid state at 120℃~400℃, and may be in a gaseous state; (c2) The melting point of the M halide is 120℃~400℃; (c3) The boiling point of the M halide is 120℃~400℃.

8. The solid-state battery according to claim 7, wherein, The M halide satisfies one or more of the following characteristics: (c1') The M halide is in a gaseous or liquid state at 150°C to 350°C, and may be in a gaseous state; optionally, the M halide is in a liquid or gaseous state at 180°C to 300°C, and may be further selected as a gaseous state; (c2') The melting point of the M halide is 150℃~350℃, and can be selected as 180℃~300℃; (c3') The boiling point of the M halide is 150℃~350℃, and can be selected as 180℃~300℃.

9. The solid-state battery according to any one of claims 1 to 8, wherein, The lithium metal halide oxide includes lithium, non-lithium metal elements, halogens, and oxygen; wherein the non-lithium metal elements include one or more of Zr, Ta, Nb, In, W, Ge, Ga, Sb, Sn, Al, and Ti.

10. The solid-state battery according to any one of claims 1 to 9, wherein, The halogens in the lithium metal halide oxide include one or more of F, Cl, Br and I.

11. The solid-state battery according to claim 10, wherein, The halogens in the lithium metal halide oxide include one or both of F and Cl.

12. The solid-state battery according to any one of claims 1 to 11, wherein, The atomic molar ratio of halogen to oxygen in the lithium metal halide oxide is (1-4):(0.8-1.2).

13. The solid-state battery according to any one of claims 1 to 11, wherein, The atomic molar ratio of halogen to oxygen in the lithium metal halide oxide is (2-5):

1.

14. The solid-state battery according to any one of claims 1 to 12, wherein, The chemical formula of the lithium metal halide oxide is Li a M b O c X d The M element in the lithium metal halide oxide includes one or more of Zr, Ta, Nb, In, W, Ge, Ga, Sb, Sn, Al, and Ti; a is 1 to 2, b is 0.8 to 1.2, c is 0.8 to 1.2, d is 1 to 4, and X is a halogen.

15. The solid-state battery according to claim 14, wherein, The X element in the lithium metal halide oxide is selected from one or both of F and Cl.

16. The solid-state battery according to any one of claims 1 to 15, wherein, The positive electrode active material D v 50 is 1μm to 8μm, and can be selected from 3μm to 6μm, where D v 50 represents the particle size at which the cumulative volume distribution percentage of the multi-particle mixture reaches 50%.

17. The solid-state battery according to any one of claims 1 to 16, wherein, The lithium transition metal oxide includes one or more of lithium nickel-based oxides, lithium-rich manganese-based cathode active materials, spinel lithium manganese oxide, and lithium cobalt oxide.

18. The solid-state battery according to claim 17, wherein, The lithium transition metal oxide includes lithium nickel-based oxide; wherein, the lithium nickel-based oxide includes Li, non-lithium metal elements and O, and the non-lithium metal elements include Ni. The lithium transition metal oxide satisfies one or more of the following characteristics: (i1) The atomic molar ratio of Ni to the non-lithium metal element in the lithium nickel-based oxide is q1, where 0.5 ≤ q1 ≤ 1; (i2) The lithium nickel-based oxide contains Ni and Li elements in an atomic molar ratio of q2:x2, wherein 0.5≤q2≤1 and 0.6≤x2≤1.2; (i3) The lithium nickel-based oxide contains Ni and O elements in an atomic molar ratio of q3:x3, wherein 0.5≤q3≤1 and 1.6≤x3≤2.2; (i4) The lithium nickel-based oxide contains Co; (i5) The lithium nickel-based oxide contains the element Mn; (i6) The lithium nickel-based oxide has a layered crystal structure.

19. The solid-state battery according to claim 18, wherein, The lithium transition metal oxide satisfies one or more of the following characteristics: (t1)0.6≤q1≤1; optionally, 0.6≤q1≤0.96; (t2)0.6≤q2≤1; optionally, 0.6≤q2≤0.96; (t3)0.6≤x2≤1.1; (t4)0.6≤q3≤1; optionally, 0.6≤q3≤0.96; (t5)1.8≤x3≤2.1; (t6) The lithium nickel-based oxide contains Co, and the atomic molar ratio of Co to non-lithium metal elements in the lithium nickel-based oxide is q4, wherein 0.02≤q4≤0.35; (t7) The lithium nickel-based oxide contains Mn element, and the atomic molar ratio of Mn element to non-lithium metal element in the lithium nickel-based oxide is q5, wherein 0.01≤q5≤0.38; (t8) The lithium nickel-based oxide accounts for 80% to 100% of the mass of the lithium transition metal oxide.

20. The solid-state battery according to claim 18, wherein, The lithium transition metal oxide satisfies one or more of the following characteristics: (t1')0.5≤q1≤0.99; optionally, 0.5≤q1≤0.9; (t2')0.5≤q2≤0.99; optionally, 0.5≤q2≤0.9; (t3')0.8≤x2≤1.1; (t4')0.5≤q3≤0.99; optionally, 0.5≤q3≤0.9; (t5')1.8≤x3≤2.06; (t6') The lithium nickel-based oxide contains Co, with 0.05 ≤ q4 ≤ 0.25; (t7') The lithium nickel-based oxide contains Mn element, 0.05≤q5≤0.3; (t8') The lithium nickel-based oxide accounts for 90% to 100% of the mass of the lithium transition metal oxide; (t9') The lithium transition metal oxide includes lithium nickel cobalt manganese-based oxide, and optionally, the lithium nickel cobalt manganese-based oxide accounts for 80% to 100% of the mass of the lithium transition metal oxide, and more preferably 90% to 100%; (t10') The lithium transition metal oxide includes lithium nickel cobalt manganese-based oxides; in the lithium nickel cobalt manganese-based oxides, the ratio of the sum of the atomic molar ratios of nickel, cobalt, and manganese to the sum of the atomic molar ratios of non-lithium metal elements is denoted as R. NCM R NCM The value is 0.9 to 1; optionally, R NCM It ranges from 0.95 to 1.

21. The solid-state battery according to any one of claims 1 to 20, wherein, The positive electrode active material satisfies one or more of the following characteristics: (e1) The lithium metal halide oxide has an ionic conductivity at 25°C greater than or equal to 1 mS / cm, and can be selected as 1 mS / cm to 10 mS / cm. (e2) The ionic conductivity of the positive electrode active material at 25℃ is greater than or equal to 0.01 mS / cm; (e3) The positive electrode active material or the coated oxide active material has an ionic conductivity at 25°C greater than or equal to 0.01 mS / cm.

22. The solid-state battery according to any one of claims 1 to 21, wherein, The solid electrolyte material includes sulfide solid electrolytes.

23. The solid-state battery according to claim 22, wherein, The sulfide solid electrolyte includes one or more of the following: silver sulfide-germanium sulfide type sulfide electrolyte, LGPS type sulfide electrolyte, and lithium sulfide-phosphorus pentasulfide complex type sulfide electrolyte; The sulfide solid electrolyte satisfies one or more of the following characteristics: (f1) The sulfide electrolyte of the silver-germanium sulfide type includes 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 1 Selected from one or more elements of Ge, Si, Sn, and Sb, B 1 X is selected from one or more elements of O, Se, and Te. 1 One or more elements selected from Cl, Br, I, and F; (f2) The LGPS-type sulfide electrolyte includes 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 One or more elements selected from O, Se, Te, Cl, Br, I, and F; (f3) The lithium sulfide pentaphosphine complex sulfide electrolyte comprises 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 One or more elements selected from Li, B, Ge, Si, Sn, and Sb, N 3 One or more elements selected from S, Se, Te, O, Cl, Br, I, and F.

24. The solid-state battery according to any one of claims 1 to 23, wherein, The positive electrode active layer satisfies one or more of the following characteristics: (d1) The mass percentage of the coated oxide active material in the positive electrode active material is 80% to 100%; (d2) The mass percentage of the coated oxide active material in the positive electrode active layer is 70% to 98%; (d3) The solid electrolyte material in the positive electrode active layer has a mass percentage content of 2% to 30%; (d4) The solid electrolyte material includes a sulfide solid electrolyte; the sulfide solid electrolyte has a mass percentage content of 2% to 30% in the positive electrode active layer.

25. The solid-state battery according to claim 24, wherein, The positive electrode active layer satisfies one or more of the following characteristics: (d1') The mass percentage of the coated oxide active material in the positive electrode active material is 90% to 100%; (d2') The mass percentage of the coated oxide active material in the positive electrode active layer is 75% to 95%; (d3') The solid electrolyte material in the positive electrode active layer has a mass percentage content of 5% to 25%; (d4') The solid electrolyte material includes a sulfide solid electrolyte; the sulfide solid electrolyte has a mass percentage content of 5% to 25% in the positive electrode active layer.

26. The solid-state battery according to any one of claims 22 to 25, wherein, The solid electrolyte material includes a sulfide solid electrolyte; the sulfide solid electrolyte has a mass percentage content of 5% to 12% in the positive electrode active layer, and can be selected as 5% to 10%. Optionally, the solid electrolyte material has a mass percentage content of 5% to 12% in the positive electrode active layer, and can be optionally 5% to 10%.

27. The solid-state battery according to any one of claims 1 to 26, wherein, It meets one or more of the following characteristics: (u1) The solid-state battery mentioned is an all-solid-state battery; (u2) The solid-state battery is a lithium-ion secondary battery, which can be selected as an all-solid-state lithium-ion secondary battery.

28. The solid-state battery according to any one of claims 1 to 27, wherein, The charging cutoff voltage of the solid-state battery is 3.8V to 4.8V, and can be selected as 4.0V to 4.5V.

29. A positive electrode active material, wherein, The positive electrode active material includes a coated oxide active material, which includes a positive electrode active body and a coating layer located on at least a portion of the surface of the positive electrode active body. The positive electrode active body includes a lithium transition metal oxide, and the coating layer includes a lithium metal halide oxide. The average thickness of the coating layer in the coated oxide active material is denoted as D1, and the ratio of ΔD to D1 is denoted as R1; the coated oxide active material satisfies one or both of the following characteristics: (v1) ΔD≤50nm; (v2) R1≤0.

5.

30. The positive electrode active material according to claim 29, wherein, The positive electrode active material comprises the characteristics of the positive electrode active material in the solid-state battery according to any one of claims 2 to 17.

31. The positive electrode active material according to claim 29, wherein, The lithium transition metal oxide includes lithium nickel-based oxides; The lithium transition metal oxide satisfies one or more of the following characteristics: (j1) The atomic molar ratio of Ni element to non-lithium metal element in the lithium nickel-based oxide is q1, where 0.5≤q1≤1; (j2) The lithium nickel-based oxide contains Ni and Li elements in an atomic molar ratio of q2:x2, wherein 0.5≤q2≤1 and 0.9≤x2≤1.1; (j3) The lithium nickel-based oxide contains Ni and O elements in an atomic molar ratio of q3:x3, wherein 0.5≤q3≤1 and 1.8≤x3≤2.1; (j4) The lithium nickel-based oxide contains Co. (j5) The lithium nickel-based oxide contains the element Mn; (j6) The lithium nickel-based oxide has a layered crystal structure.

32. The positive electrode active material according to claim 31, wherein, The lithium transition metal oxide satisfies one or more of the following characteristics: (z1)0.6≤q1≤1; optionally, 0.6≤q1≤0.96; (z2)0.6≤q2≤1; optionally, 0.6≤q2≤0.96; (z3)0.98≤x2≤1.02; (z4)0.6≤q3≤1; optionally, 0.6≤q3≤0.96; (z5)1.96≤x3≤2.04; (z6) The lithium nickel-based oxide contains Co, and the atomic molar ratio of Co to non-lithium metal elements in the lithium nickel-based oxide is q4, wherein 0.02≤q4≤0.35; (z7) The lithium nickel-based oxide contains Mn element, and the atomic molar ratio of Mn element to non-lithium metal element in the lithium nickel-based oxide is q5, wherein 0.01≤q5≤0.38; (z8) The lithium nickel-based oxide accounts for 80% to 100% of the mass of the lithium transition metal oxide.

33. The positive electrode active material according to claim 32, wherein, The lithium transition metal oxide satisfies one or more of the following characteristics: (z1')0.5≤q1≤0.99; optionally, 0.5≤q1≤0.9; (z2')0.5≤q2≤0.99; optionally, 0.5≤q2≤0.9; (z3')0.99≤x2≤1.01; (z4')0.5≤q3≤0.99; optionally, 0.5≤q3≤0.9; (z5')1.98≤x3≤2.02; (z6') The lithium nickel-based oxide contains Co element, 0.05≤q4≤0.25; (z7') The lithium nickel-based oxide contains Mn element, 0.02≤q5≤0.3; (z8') The lithium nickel-based oxide accounts for 90% to 100% of the mass of the lithium transition metal oxide; (z9') The lithium transition metal oxides include lithium nickel cobalt manganese-based oxides.

34. The positive electrode active material according to any one of claims 29 to 33, wherein, The positive electrode active material satisfies one or more of the following characteristics: (g1) The lithium transition metal oxide includes lithium nickel cobalt manganese-based oxides; in the lithium nickel cobalt manganese-based oxides, the ratio of the sum of the atomic molar ratios of nickel, cobalt, and manganese to the sum of the atomic molar ratios of non-lithium metal elements is denoted as R. NCM R NCM The value is 0.9 to 1; optionally, R NCM It ranges from 0.95 to 1; (g2) The mass percentage of the coated oxide active material in the positive electrode active material is 80% to 100%, and can be 90% to 100%; (g3) The lithium metal halide oxide has an ionic conductivity at 25°C greater than or equal to 1 mS / cm, and can be selected as 1 mS / cm to 10 mS / cm. (g4) The ionic conductivity of the positive electrode active material at 25℃ is greater than or equal to 0.01 mS / cm; (g5) The ionic conductivity of the coated oxide active material at 25°C is greater than or equal to 0.01 mS / cm.

35. A method for preparing a coated oxide-based active material, comprising the following steps: Provide oxide-based positive electrode active materials; among which, The oxide-based positive electrode active material includes a positive electrode active body and a lithium-containing residual alkali located on at least a portion of the surface of the positive electrode active body, wherein the positive electrode active body includes a lithium transition metal oxide. Under selected atmosphere and heating conditions, the oxide-based positive electrode active material is subjected to an in-situ coating reaction with a non-solid metal halide, so that the lithium-containing residual alkali reacts with the non-solid metal halide to form lithium metal halide oxide. After cooling, a coated oxide-based active material is obtained; wherein, the selected atmosphere is a vacuum condition or an inert gas atmosphere, and the metal element in the non-solid metal halide is a non-lithium metal element. The average thickness of the coating layer in the coated oxide active material is denoted as D1, and the ratio of ΔD to D1 is denoted as R1; the coated oxide active material satisfies one or both of the following characteristics: (v1) ΔD≤50nm; (v2) R1≤0.

5.

36. The method for preparing the coated oxide-based active material according to claim 35, wherein it satisfies one or more of the following characteristics: (h1) The non-solid metal halide is one or both of gaseous and liquid states; (h2) The melting point of the non-solid metal halide is 120℃~400℃, optionally 150℃~350℃, and further optionally 180℃~300℃; (h3) The boiling point of the non-solid metal halide is 120℃~400℃, optionally 150℃~350℃, and further optionally 180℃~300℃; (h4) The temperature for carrying out the in-situ coating reaction is 120℃~400℃, optionally 150℃~350℃, and further optionally 180℃~300℃; optionally, the reaction time is 2h~6h; (h5) The metal element in the non-solid metal halide includes one or more of Zr, Ta, Nb, In, W, Ge, Ga, Sb, Sn, Al and Ti; (h6) The halogen in the non-solid metal halide includes one or more of F, Cl, Br and I.

37. The method for preparing the coated oxide-based active material according to any one of claims 35 or 36, wherein, It meets one or more of the following characteristics: (k1) The non-solid metal halide is in a gaseous state; (k2) The lithium transition metal oxide includes one or more of lithium nickel-based oxides, lithium-rich manganese-based positive electrode active materials, spinel lithium manganese oxide, and lithium cobalt oxide; (k3) The lithium-containing residual alkali includes one or more of lithium carbonate and lithium hydroxide; (k4) In the oxide-based positive electrode active material, the mass percentage of the lithium-containing residual alkali is 0.5% to 2%; (k5) The initial ratio of the oxide-based positive electrode active material to the non-solid metal halide salt is (30-50):1, based on the amount of material fed. (k6) Based on the amount of material fed, the atomic molar ratio of halogen in the non-solid metal halide to oxygen in the oxide-type positive electrode active material is (1-4):(0.8-1.2), which can be selected as 1-5, and further selected as 2-5; (k7) The lithium metal halide oxide has an ionic conductivity of 1 mS / cm to 10 mS / cm at 25 °C. (k8) The ionic conductivity of the coated oxide active material prepared at 25℃ is greater than or equal to 0.01 mS / cm; (k9) The coated oxide active material obtained includes the characteristics of the coated oxide active material in any one of claims 29 to 34.

38. A positive electrode sheet comprising a positive active layer, wherein the positive active layer comprises at least one of the positive active material according to any one of claims 29 to 34 and the coated oxide active material prepared by the preparation method of the coated oxide active material according to any one of claims 35 to 37, or the positive active layer comprises the characteristics of the positive active layer in a solid-state battery according to any one of claims 1 to 28.

39. An electrical device comprising at least one of the following: a solid-state battery according to any one of claims 1 to 28; a positive electrode active material according to any one of claims 29 to 34; a coated oxide active material prepared by the method for preparing a coated oxide active material according to any one of claims 35 to 37; and a positive electrode sheet according to claim 38.

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