Solid-state lithium metal battery and electronic apparatus

Abstract

The present application provides a solid-state lithium metal battery and an electronic apparatus. The solid-state lithium metal battery comprises a positive electrode layer, a negative electrode current collector, and an electrolyte layer arranged between the positive electrode layer and the negative electrode current collector. The positive electrode layer comprises a positive electrode current collector and a positive electrode active material layer, and the positive electrode active material layer is arranged on the surface of the positive electrode current collector that faces the electrolyte layer. The electrolyte layer comprises an oxide solid-state electrolyte sheet and a graphite modification layer, and the graphite modification layer is arranged on the surface of the oxide solid-state electrolyte sheet that faces a negative electrode layer. A metal layer and a lithiation polymer interface layer are arranged on the surface of the negative electrode current collector that faces the electrolyte layer, and the metal layer is located between the negative electrode current collector and the lithiation polymer interface layer. Through such arrangement of the graphite modification layer, the metal layer and the lithiation polymer interface layer, the initial coulombic efficiency and the cycle performance of the solid-state lithium metal battery of the present application are improved.

Description

Solid-state lithium metal battery and electronic device Technical Field

[0001] The present application relates to the field of electrochemical technology, and in particular to a solid-state lithium metal battery and an electronic device. Background Art

[0002] Existing solid-state lithium metal batteries use solid-state electrolytes instead of traditional organic electrolytes to effectively improve the safety performance of lithium-ion batteries. However, due to poor solid-solid interface contact between the solid electrolyte and the copper current collector and the dramatic volume expansion during lithium metal deposition, solid-state lithium metal batteries have high impedance and uneven lithium metal deposition. Therefore, negative electrode-less solid-state lithium metal batteries often suffer from low initial coulombic efficiency and poor cycle performance, limiting their practical application. Therefore, how to improve the initial coulombic efficiency and cycle performance of solid-state lithium metal batteries has become a technical problem that needs to be solved urgently by those skilled in the art.

[0003] Summary of the Invention

[0004] The present application provides a solid-state lithium metal battery and an electronic device to improve the first coulombic efficiency and cycle performance of the solid-state lithium metal battery.

[0005] The first aspect of the present application provides a solid-state lithium metal battery, which includes a positive electrode layer, a negative electrode current collector, and an electrolyte layer arranged between the positive electrode layer and the negative electrode current collector; the positive electrode layer includes a positive electrode current collector and a positive electrode active material layer, the positive electrode active material layer is arranged on the surface of the positive electrode current collector facing the electrolyte layer; the electrolyte layer includes an oxide solid electrolyte sheet and a graphite modification layer, the graphite modification layer is arranged on the surface of the oxide solid electrolyte sheet facing the negative electrode current collector; a metal layer and a lithiated polymer interface layer are arranged on the surface of the negative electrode current collector facing the electrolyte layer, the metal layer is located between the negative electrode current collector and the lithiated polymer interface layer. By arranging the graphite modification layer, the metal layer and the lithiated polymer interface layer between the oxide solid electrolyte sheet and the negative electrode current collector, the possibility of physical contact between the solid-solid interface of the oxide solid electrolyte sheet and the negative electrode current collector can be reduced, the impedance of the solid-state lithium metal battery can be reduced, the problem of uneven lithium deposition can be improved, and the risk of short circuit of the solid-state lithium metal battery due to the growth of lithium dendrites can be reduced. As a result, the first coulombic efficiency and cycle performance of the solid-state lithium metal battery of the present application are improved.

[0006] In some embodiments of the present application, the negative electrode current collector is selected from a copper current collector; and the metal layer comprises at least one of aluminum, silver, zinc, silicon, or tin. The copper current collector and the metal layer are advantageously used to improve the initial coulombic efficiency and cycling performance of solid-state lithium metal batteries.

[0007] In some embodiments of the present application, the material of the lithiated polymer interface layer includes at least one of lithium poly(acrylate), lithium carboxymethyl cellulose, lithium alginate, or lithium polymethyl methacrylate. Selecting the above types of materials as the lithiated polymer interface layer is beneficial to improving the initial Coulombic efficiency and cycling performance of the solid-state lithium metal battery.

[0008] In some embodiments of the present application, the material of the graphite modification layer is Li x C6, where 0 ≤ x ≤ 1. Selecting the above types of materials as the graphite modification layer is beneficial to improving the initial Coulombic efficiency and cycling performance of the solid-state lithium metal battery.

[0009] In some embodiments of the present application, the material of the oxide solid electrolyte sheet includes at least one of the following compounds: lithium aluminum germanium phosphate Li 1+x1 Al x1 Ge 2-x1 (PO4)3 or its isomorphous heteroatom-doped compounds, lithium aluminum titanium phosphate Li 1+x2 Al x2 Ti 2-x2 (PO4)3 or its isomorphous heteroatom-doped compounds, lithium lanthanum titanate Li 3x3 L a2 / 3-x3 TiO3 or its isomorphous heteroatom-doped compounds, lithium lanthanum zirconium oxide Li 7-x4 La3Zr 2-x4 O 12 or its isomorphous heteroatom-doped compounds, inverse perovskite structure Li 3-2x5 M x5 HalO, Li3OCl or its isomorphous heteroatom-doped compounds, LISICON structure Li 4-x6 Si 1-x6 P x6 O4 or its isomorphous heteroatom-doped compounds, Li 14 ZnGe4O 16 or its isomorphous heteroatom-doped compounds; where 0 < x1 ≤ 0.75, 0 < x2 ≤ 0.5, 0.06 ≤ x3 ≤ 0.14, 0 ≤ x4 < 1, 0 ≤ x5 ≤ 0.01, 0.5 ≤ x6 ≤ 0.6, Hal is the element Cl or I, and the heteroatoms of each compound are independently selected from at least one of Al, Ta, Nb, Ti, Ge, F, Br or V. Selecting the above types of materials as the oxide solid electrolyte sheet is beneficial to improving the initial Coulombic efficiency and cycling performance of the solid-state lithium metal battery.

[0010] In some embodiments of the present application, the thickness of the metal layer is 0.1 μm to 5 μm. Preferably, the thickness of the metal layer is 1 μm to 3 μm. Controlling the thickness of the metal layer within the above range is beneficial for improving the initial coulombic efficiency, energy density, and cycle performance of solid-state lithium metal batteries.

[0011] In some embodiments of the present application, the thickness of the lithiated polymer interface layer is 0.1 μm to 5 μm. Preferably, the thickness of the lithiated polymer interface layer is 1 μm to 3 μm. Controlling the thickness of the lithiated polymer interface layer within the above range is beneficial for improving the initial coulombic efficiency, energy density, and cycling performance of solid-state lithium metal batteries.

[0012] In some embodiments of the present application, the thickness of the graphite-modified layer is 0.1 μm to 5 μm. Preferably, the thickness of the graphite-modified layer is 1 μm to 3 μm. Controlling the thickness of the graphite-modified layer within the above range is beneficial for improving the initial coulombic efficiency, energy density, and cycling performance of solid-state lithium metal batteries.

[0013] In some embodiments of the present application, the thickness of the oxide solid electrolyte sheet is 0.01 mm to 1 mm. Controlling the thickness of the oxide solid electrolyte sheet within the above range is beneficial for improving the initial coulombic efficiency, energy density, and cycle performance of solid-state lithium metal batteries.

[0014] A second aspect of the present application provides an electronic device comprising the solid-state lithium metal battery according to any of the aforementioned embodiments. Therefore, the electronic device has good performance.

[0015] Beneficial effects of this application:

[0016] The present application provides a solid-state lithium metal battery and electronic device, wherein the solid-state lithium metal battery includes a positive electrode layer, a negative electrode current collector, and an electrolyte layer disposed between the positive electrode layer and the negative electrode current collector; the positive electrode layer includes a positive electrode current collector and a positive electrode active material layer, the positive electrode active material layer being disposed on the surface of the positive electrode current collector facing the electrolyte layer; the electrolyte layer includes an oxide solid electrolyte sheet and a graphite modification layer, the graphite modification layer being disposed on the surface of the oxide solid electrolyte sheet facing the negative electrode layer; a metal layer and a lithiated polymer interface layer are disposed on the surface of the negative electrode current collector facing the electrolyte layer, the metal layer being located between the negative electrode current collector and the lithiated polymer interface layer. By disposing the graphite modification layer, the metal layer, and the lithiated polymer interface layer, the first coulombic efficiency and cycle performance of the solid-state lithium metal battery of the present application are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings described herein are used to provide further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute improper limitations on the present application.

[0018] FIG1 is a schematic diagram of a cross-sectional structure of a solid-state lithium metal battery along its thickness direction in some embodiments of the present application;

[0019] FIG2 is a schematic diagram of a cross-sectional structure of a solid-state lithium metal battery along its thickness direction in other embodiments of the present application;

[0020] FIG3 is a specific capacity-voltage test diagram of Example 1-1 of the present application;

[0021] FIG4 is a test graph of cycle number-specific capacity-Coulombic efficiency of Example 1-1 of the present application;

[0022] FIG5 is a specific capacity-voltage test diagram of Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0023] To make the objectives, technical solutions, and advantages of this application more clearly understood, the present application is further described below with reference to the accompanying drawings and examples. It is apparent that the described examples are only a portion of the embodiments of this application, and not all of them. All other embodiments derived by persons of ordinary skill in the art based on the examples in this application are intended to fall within the scope of protection of this application.

[0024] Conventional lithium-ion batteries use graphite as the negative electrode (gram capacity 372 mAh / g), and its energy density is close to the limit, making it difficult to meet the growing demand for electric vehicles and grid storage. Using lithium metal as the negative electrode can greatly improve the energy density of the battery because it has a low potential (-3.04 V versus SHE) and a high theoretical capacity. Negative-electrode lithium metal batteries directly use copper foil as the negative electrode. During the charging process, the lithium ions released from the positive electrode are deposited in situ on the negative electrode to form a lithium metal negative electrode. Therefore, based on this battery structure, negative-electrode lithium metal batteries have the following advantages: (1) Improve the volume energy density and mass energy density of lithium-ion batteries; (2) Because a large amount of lithium metal is not used, it is beneficial to improve the safety of lithium-ion batteries; (3) Because ultra-thin lithium metal is not required, the manufacturing process can be simplified. Moreover, in solid-state lithium metal batteries, the use of solid electrolytes instead of traditional organic electrolytes can improve the safety performance of solid-state lithium metal batteries. However, at present, due to the poor solid-solid interface contact between the solid electrolyte and the copper current collector, and the violent volume expansion during lithium metal deposition, the solid-state lithium metal battery has high impedance and uneven lithium metal deposition. Therefore, the negative electrode-free solid-state lithium battery often has problems such as low first coulombic efficiency and poor cycle performance, which limits its practical application.

[0025] As shown in FIG1 , the first aspect of the present application provides a solid-state lithium metal battery 100, which includes a positive electrode layer 10, a negative electrode current collector 30, and an electrolyte layer 20 disposed between the positive electrode layer 10 and the negative electrode current collector 30. The positive electrode layer 10 includes a positive electrode current collector 11 and a positive electrode active material layer 12, with the positive electrode active material layer 12 disposed on a surface 11a of the positive electrode current collector 11 facing the electrolyte layer 20. The electrolyte layer 20 includes an oxide solid electrolyte sheet 21 and a graphite modified layer 22, with the graphite modified layer 22 disposed on a surface 21a of the oxide solid electrolyte sheet 21 facing the negative electrode current collector 30. A metal layer 40 and a lithiated polymer interface layer 50 are disposed on a surface 30b of the negative electrode current collector 30 facing the electrolyte layer 20, with the metal layer 40 located between the negative electrode current collector 30 and the lithiated polymer interface layer 50. The graphite modified layer 22 has a good improvement effect on lithium ion conduction and has good interfacial contact with the oxide solid electrolyte sheet 21, thereby effectively uniformizing the lithium ion flux. The negative electrode current collector 30 (made of metals such as Cu, Ni, etc.) does not undergo an alloying reaction with Li and is usually in a lithium-phobic state. During the lithium deposition process, uneven lithium deposition and lithium dendrite growth can easily lead to short circuits in solid-state lithium metal batteries. The metal in the metal layer 40 can react with Li to form an alloy, increase the nucleation sites of lithium and reduce the nucleation overpotential of lithium, thereby solving the problem of high nucleation overpotential of Li on the negative electrode current collector. In this way, the uneven deposition of lithium ions on the negative electrode current collector 30 and the growth behavior of lithium dendrites can be improved. The provision of the lithiated polymer interface layer 50 can improve the contact between the oxide solid electrolyte sheet 21 and the negative electrode current collector 30 and buffer the stress generated by volume changes during lithium deposition. In addition, the material in the lithiated polymer interface layer 50 has been lithiated and will not cause additional consumption of lithium ions.

[0026] In general, by providing a graphite modified layer 22, a metal layer 40, and a lithiated polymer interface layer 50 between the oxide solid electrolyte sheet 21 and the negative electrode current collector 30, the solid-solid interface physical contact between the oxide solid electrolyte sheet 21 and the negative electrode current collector 30 can be improved, reducing the impedance of the solid-state lithium metal battery. It can also improve the problem of uneven lithium deposition and reduce the risk of short circuits in the solid-state lithium metal battery due to the growth of lithium dendrites. As a result, the first coulombic efficiency and cycle performance of the solid-state lithium metal battery of the present application are improved.

[0027] In some embodiments of the present application, as shown in FIG. 2 , the positive electrode active material layer 12 may also be provided on the surface 11 b of the positive electrode current collector 11 facing away from the electrolyte layer 20 .

[0028] In some embodiments of the present application, the negative electrode current collector is selected from a copper current collector; the material of the metal layer includes at least one of aluminum, silver, zinc, silicon or tin, and preferably, the material of the metal layer is silver. The negative electrode current collector is selected from a copper current collector, and the above-mentioned types of materials are selected as the metal layer. The metal in the metal layer reacts with Li to form an alloy, which can increase the nucleation sites of lithium and reduce the nucleation overpotential of lithium, thereby solving the problem of high nucleation overpotential of Li on the negative electrode current collector. In this way, the uneven deposition of lithium ions on the negative electrode current collector and the growth behavior of lithium dendrites can be improved. This is conducive to improving the first coulombic efficiency and cycle performance of solid-state lithium metal batteries.

[0029] In some embodiments of the present application, the material of the lithiated polymer interface layer includes at least one of lithium poly(acrylic acid) (LiPAA), lithium carboxymethyl cellulose (LiCMC), lithium sodium alginate, or lithium polymethyl methacrylate (LiPMMA). The above-mentioned types of materials are selected as the lithiated polymer interface layer. The lithiated polymer interface layer has good bonding ability and good elasticity, which can improve the contact between the oxide solid electrolyte sheet and the negative electrode current collector and buffer the stress generated by volume change during lithium deposition. In addition, the material in the lithiated polymer interface layer has been lithiated and will not cause additional consumption of lithium ions. This is conducive to improving the first coulombic efficiency and cycle performance of the solid-state lithium metal battery.

[0030] The present application does not particularly limit the weight average molecular weight of the above-mentioned lithium poly(acrylic acid), lithium carboxymethyl cellulose, lithium sodium alginate, and lithium polymethyl methacrylate, as long as the purpose of the present application can be achieved. For example, the weight average molecular weight of lithium poly(acrylic acid) is 2,000 to 450,000, the weight average molecular weight of lithium carboxymethyl cellulose is 90,000 to 700,000, the weight average molecular weight of lithium sodium alginate is 20,000 to 50,000, and the weight average molecular weight of lithium polymethyl methacrylate is 100,000 to 350,000.

[0031] The present application has no particular restrictions on the method for controlling the weight average molecular weight of the above-mentioned lithium poly(acrylic acid), lithium carboxymethyl cellulose, lithium sodium alginate, and lithium polymethyl methacrylate, as long as the purpose of the present application can be achieved. For example, they can be purchased directly from manufacturers.

[0032] In some embodiments of the present application, the material of the graphite modification layer is Li x C6, 0≤x≤1. In some embodiments of the present application, the material of the graphite modification layer is Li x C6, x=0. In other embodiments of the present application, the material of the graphite modification layer is Li x C6, 0<x≤1. Preferably, Li x In C6, x=1. Graphite is a good lithium ion conductor. Chemical pre-lithiation of graphite forms Lix C6 can further improve lithium ion conduction. Selecting the materials of the above types as the graphite modification layer has a good improvement effect on lithium ion conduction, has good interfacial contact with the oxide solid electrolyte sheet, can better uniform the lithium ion flux, and then improve the problem of uneven lithium deposition. This is conducive to improving the initial Coulomb efficiency and cycling performance of the solid-state lithium metal battery. The above "chemical prelithiation" is the "chemical prelithiation" well-known in the art.

[0033] In some embodiments of the present application, the material of the oxide solid electrolyte sheet includes at least one of the following compounds: lithium aluminum germanium phosphate Li 1+x1 Al x1 Ge 2-x1 (PO4)3 (LAGP) or its isomorphous heteroatom-doped compounds, lithium aluminum titanium phosphate Li 1+x2 Al x2 Ti 2-x2 (PO4)3 (LATP) or its isomorphous heteroatom-doped compounds, lithium lanthanum titanate Li 3x3 L a2 / 3-x3 TiO3 (LLTO) or its isomorphous heteroatom-doped compounds, lithium lanthanum zirconium oxide Li 7-x4 La3Zr 2-x4 O 12 (LLZO) or its isomorphous heteroatom-doped compounds, Li 3-2x5 M x5 HalO, Li3OCl or its isomorphous heteroatom-doped compounds, Li 4-x6 Si 1-x6 P x6 O4 or its isomorphous heteroatom-doped compounds, Li 14 ZnGe4O 16 ; wherein, 0 < x1 ≤ 0.75, 0 < x2 ≤ 0.5, 0.06 ≤ x3 ≤ 0.14, 0 ≤ x4 < 1, 0 ≤ x5 ≤ 0.01, 0.5 ≤ x6 ≤ 0.6, Hal is the element Cl or I, and the heteroatoms of each compound are independently selected from at least one of Al, Ta, Nb, Ti, Ge, F, Br, V. Selecting the materials of the above types as the oxide solid electrolyte sheet is conducive to the transmission of lithium ions, reduces the interfacial side reactions between the electrolyte and the electrode (the positive electrode sheet and / or the negative electrode sheet), and inhibits the growth of lithium dendrites, thereby being conducive to improving the initial Coulomb efficiency and cycling performance of the solid-state lithium metal battery.

[0034] Preferably, the material of the oxide solid electrolyte sheet includes at least one of the following compounds: LLZO, LATP, LAGP.

[0035] In some embodiments of the present application, NASICON structured lithium germanium aluminum phosphate Li 1+x1 Al x1 Ge 2-x1 (PO4)3 isomorphous heteroatom doping compounds include Li 1.6 Al 0.4 Mg 0.1 Ge 1.5 (PO4)3 or Li 1.5 Al 0.5-x Ga x Ge 1.5 (PO4)3 etc., at least one of lithium titanium aluminum phosphate Li 1+x2 Al x2 Ti 2-x2 (PO4)3 isomorphous heteroatom doping compounds include Li 1.3 Al 0.5 Nb 0.2 Ti 1.3 (PO4)3、Li 1.3 Al 0.3 Ti 1.7 (PO4) 2.9 (VO4) 0.1 At least one of the following, perovskite structured lanthanum titanate lithium Li 3x3 L a2 / 3-x3 TiO3 isomorphous heteroatom doping compounds include Li 0.36 La 0.55 Ti 0.95 Ge 0.05 O3、Li 0.36 La 0.55 Ti 0.95 Ti 0.05 O3、Li 0.36 La 0.56 Ti 0.97 Al 0.03 At least one of O3, etc., garnet structure lithium lanthanum zirconium oxide Li 7-x4 La3Zr 2-x4 O 12 Isomorphous heteroatom doping compounds include Li 6.5 La3Za 1.5 Ta 0.5 O 12 (LLZTO), Li 6.75 La3Zr 1.75 Nb 0.25 O 12 (LLZNO), Li 6.25 La3Zr2Al 0.25 O 12At least one of the following, the Li3OCl isomorphous heteroatom doping compound includes Li3OCl 0.5 Br 0.5 、Li3OCl 0.5 F 0.5 At least one of the following, Li with LISICON structure 4-x6 Si 1-x6 P x6 O4 isomorphous heteroatom doping compounds include Li 4.25 Si 0.75 Al 0.25 O4、Li4Al 0.33 Si 0.33 P 0.33 At least one of O4, etc.

[0036] In some embodiments of the present application, as shown in FIG1 , the thickness t of the metal layer 40 is 40 The thickness of the metal layer 40 is 0.1 μm to 5 μm, preferably 1 μm to 3 μm. For example, the thickness of the metal layer 40 is 0.1 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm or any value between any two of the above ranges. 40 By regulating within the above range, the negative electrode current collector 30 is completely covered by the metal layer 40, and lithium deposition is relatively uniform on the exposed areas of the negative electrode current collector 30. This can also reduce the risk of all lithium ions alloying with the metal layer, causing an increase in the negative electrode potential and thus reducing the energy density of the solid-state lithium metal battery 100. This is conducive to improving the initial coulombic efficiency, cycle performance, and energy density of the solid-state lithium metal battery 100.

[0037] In some embodiments of the present application, as shown in FIG1 , the thickness t of the lithiated polymer interface layer 50 is 50 is 0.1 μm to 5 μm, preferably 1 μm to 3 μm. For example, the thickness t of the lithiated polymer interface layer 50 is 50 The thickness t of the lithiated polymer interface layer 50 is 0.1 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm or any value between any two of the above ranges. 50 By regulating within the above range, the lithiated polymer can be evenly distributed on the metal layer 40, can evenly improve the interface contact between the oxide solid electrolyte sheet 21 and the negative electrode current collector 30, and can reduce the interface impedance and reduce the polarization of the solid-state lithium metal battery 100, thereby facilitating the improvement of the first coulombic efficiency and cycle performance of the solid-state lithium metal battery 100.

[0038] In some embodiments of the present application, as shown in FIG1 , the thickness t of the graphite modification layer 22 is 22 is 0.1 μm to 5 μm, preferably 1 μm to 3 μm. For example, the thickness t of the graphite modified layer 22 is22 The thickness t of the graphite modified layer 22 is 0.1 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm or any value between any two of the above ranges. 22 By regulating within the above range, the graphite-modified layer 22 can be evenly distributed on the lithiated polymer interface layer 50, the lithium ion flux is uniform in the exposed area of ​​the negative electrode current collector 30, and the graphite-modified layer 22 is well bonded to the oxide solid electrolyte sheet 21. This reduces the risk of loss of volumetric energy density due to excessive volume in the solid-state lithium metal battery 100. This is conducive to improving the initial coulombic efficiency, energy density, and cycle performance of the solid-state lithium metal battery 100.

[0039] In some embodiments of the present application, as shown in FIG1 , the thickness t of the oxide solid electrolyte sheet 21 is 21 For example, the thickness t of the oxide solid electrolyte sheet 21 is 0.01 mm to 1 mm. 21 The thickness t of the oxide solid electrolyte sheet 21 is 0.01 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm or any value between any two of the above ranges. 21 By regulating within the above range, the oxide solid electrolyte sheet can have high mechanical strength and be less prone to breakage, while also reducing the risk of loss of volumetric energy density due to excessive volume of the solid-state lithium metal battery 100. This is beneficial for improving the initial coulombic efficiency, energy density, and cycle performance of the solid-state lithium metal battery 100.

[0040] The thickness of the negative electrode current collector is not particularly limited in this application, as long as the purpose of this application can be achieved. For example, the thickness of the negative electrode current collector is 5 μm to 30 μm.

[0041] The present application has no particular restrictions on the type of positive electrode current collector, as long as the purpose of the present application can be achieved. For example, the positive electrode current collector may include aluminum foil, aluminum alloy foil, etc. The positive electrode active material layer of the present application includes positive electrode active materials. The present application has no particular restrictions on the type of positive electrode active materials, as long as they include the transition metal elements of the present application and can achieve the purpose of the present application. For example, the positive electrode active material may include lithium nickel cobalt manganese oxide (LiNi 0.8 Co 0.1 Mn 0.1O2), lithium nickel cobalt aluminum oxide, lithium iron phosphate (LiFePO4), lithium-rich manganese-based materials, lithium cobalt oxide (LiCoO2), lithium manganese oxide, lithium iron manganese phosphate or lithium titanate, etc. In the present application, there is no particular restriction on the thickness of the positive electrode current collector and the positive electrode active material layer, as long as the purpose of this application can be achieved. In the present application, there is no particular restriction on the thickness of the positive electrode current collector and the positive electrode active material layer, as long as the purpose of this application can be achieved. For example, the thickness of the positive electrode current collector is 5μm to 20μm, preferably 6μm to 18μm. The thickness of the single-sided positive electrode active material layer is 30μm to 120μm.

[0042] Optionally, the positive electrode active material layer may further include a positive electrode conductor and a positive electrode binder. The present application has no particular restrictions on the types of positive electrode conductors and positive electrode binders in the positive electrode active material layer, as long as the purpose of the present application can be achieved. The present application has no particular restrictions on the mass ratio of the positive electrode active material, the positive electrode conductor, and the positive electrode binder in the positive electrode active material layer. Those skilled in the art can choose according to actual needs, as long as the purpose of the present application can be achieved. For example, the mass ratio of the positive electrode active material, the positive electrode conductor, and the positive electrode binder in the positive electrode active material layer is (97-98): (0.5-1.5): (1.5-3.4).

[0043] The present application has no particular restrictions on the preparation method of the solid-state lithium metal battery, and methods well known to those skilled in the art can be used, as long as the purpose of the present application can be achieved. For example, the preparation method of the solid-state lithium metal battery includes but is not limited to the following steps: the positive electrode layer, the electrolyte layer and the negative electrode layer are stacked in sequence, placed in a shell, and sealed with a sealing machine to form a solid-state lithium metal battery. The present application has no particular restrictions on the preparation method of the positive electrode layer, the electrolyte layer and the negative electrode layer, and methods well known to those skilled in the art can be used, as long as the purpose of the present application can be achieved. For example, the preparation method of the electrolyte layer includes but is not limited to the following steps: a graphite modification layer is provided on the surface of the oxide solid electrolyte sheet facing the negative electrode layer. For example, the preparation method of the negative electrode layer includes but is not limited to the following steps: a metal layer is provided on the surface of the negative electrode current collector facing the electrolyte layer, and a lithium polymer interface layer is provided on the surface of the metal layer that is not in contact with the negative electrode current collector.

[0044] In a second aspect, the present application provides an electronic device comprising the solid-state lithium metal battery according to any of the aforementioned embodiments. Therefore, the electronic device has good first coulombic efficiency and cycle performance.

[0045] The electronic device of the present application is not particularly limited and can be any electronic device known in the art. For example, the electronic device can include, but is not limited to, a laptop computer, a pen-type computer, a mobile computer, an electronic book player, a portable phone, a portable fax machine, a portable copier, a portable printer, a headset, a video recorder, an LCD television, a portable cleaner, a portable CD player, a mini-disc, a transceiver, an electronic notepad, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, an automobile, a motorcycle, a power-assisted bicycle, a bicycle, a lighting fixture, a toy, a game console, a clock, a power tool, a flashlight, a camera, a large household battery, and a lithium-ion capacitor.

[0046] Example

[0047] Hereinafter, the embodiments of the present application will be described in more detail with reference to Examples and Comparative Examples. Various tests and evaluations were performed according to the following methods.

[0048] Test methods and equipment:

[0049] It should be noted that the embodiments and comparative examples in the present application all adopt a constant current charge and discharge method and are tested using a Xinwei test cabinet (model CT-4008-5V 10mA current dual range).

[0050] The first coulombic efficiency test:

[0051] At room temperature, the solid-state lithium metal batteries of each embodiment and comparative example were charged and discharged for the first time in an environment of 25°C: constant current charging was performed at a charging current of 0.05C until the upper limit voltage reached 4.2V, and then constant current discharge was performed at a discharge current of 0.05C until the final voltage reached 2.5V. The charge specific capacity and discharge specific capacity of the first cycle were recorded. First effective coulombic efficiency = (discharge specific capacity of the first cycle / charge specific capacity of the first cycle) × 100%.

[0052] Cycle performance test:

[0053] The solid-state lithium metal batteries of the embodiments and comparative examples were repeatedly charged and discharged through the following steps, and the discharge capacity retention rate of the solid-state lithium metal batteries was calculated.

[0054] In an environment of 25°C, perform the first charge and discharge, perform constant current charging at a charging current of 0.1C until the upper limit voltage reaches 4.2V, then perform constant current discharge at a discharge current of 1C until the final voltage reaches 2.5V, record the discharge specific capacity of the first cycle, then repeat the above steps for 20 cycles of charge and discharge, and record the discharge capacity of the 20th cycle. 20-cycle cycle capacity retention = (20th cycle discharge specific capacity / first cycle discharge specific capacity) × 100%.

[0055] Example 1-1

[0056] <Preparation of positive electrode layer>

[0057] The positive electrode active material LiFePO4, the positive electrode conductive agent conductive carbon black (Super P), and the positive electrode binder polyvinylidene fluoride (abbreviated as PVDF, with a weight average molecular weight of 1100000) are mixed in a mass ratio of 97.5:1.0:1.5, and then N-methylpyrrolidone (NMP) is added as a solvent. The mixture is stirred under the action of a vacuum mixer until the solid content is 75wt% and the system is uniform. The positive electrode slurry is evenly coated on one surface of an 8μm thick positive electrode current collector aluminum foil and dried at 90°C to obtain a positive electrode layer with a single-sided coating of a positive electrode active material layer (thickness 130μm). The positive electrode active material layer is then cold pressed to 2.0g / cm 3 The compaction density is cut into positive electrode layers with a diameter of 8 mm for later use.

[0058] <Preparation of Negative Electrode Layer>

[0059] A copper current collector with a thickness of 12 μm and a diameter of 12 mm was selected as the negative electrode current collector.

[0060] On the surface of the copper current collector facing the electrolyte layer, AgNO3 solution was first added dropwise to perform ion exchange, replacing the t 40 = 1 μm thick Ag layer as the metal layer, the metal layer was washed with deionized water to remove excess impurity ions on the surface, and then dried; then a layer of 5 mg / ml LiPAA (weight average molecular weight of 450000) aqueous solution was scraped on the surface of the metal layer not in contact with the copper current collector, and dried to a thickness of t 50 =1 μm lithiated polymer interface layer to obtain a negative electrode layer of LiPAA / Ag / Cu (diameter of 12 mm).

[0061] <Preparation of Electrolyte Layer>

[0062] Li 6.5 La3Zr 1.5 Ta 0.5 O 12 Oxide solid electrolyte sheet (diameter 14mm, thickness t 21 =1 mm) was polished to remove impurities such as LiCO3 and LiOH on the surface. A 1 μm thick graphite layer was scraped on the surface of the oxide solid electrolyte sheet facing the negative electrode layer using a graphite pencil (manufacturer: China First Pencil Co., Ltd., model: 10B). The graphite layer was exposed to 150°C molten lithium at an ambient temperature of 25°C for chemical pre-lithiation until the graphite layer was lithiated to a golden Li xC6 layer (x=1), namely graphite modified layer (t 22 =1μm), the x value can be adjusted by controlling the contact time between the molten lithium and the graphite layer. Here, a LiC6 layer can be obtained when the contact time is 1min.

[0063] <Preparation of solid-state lithium metal batteries>

[0064] The electrolyte layer obtained above is flanked by a positive electrode layer and a LiPAA / Ag / Cu negative electrode layer. 10 μL of liquid electrolyte was dripped onto the surface of the electrolyte layer facing the positive electrode layer to improve contact between the electrolyte layer and the positive electrode layer. The negative electrode layer was then attached to the surface of the electrolyte layer facing away from the positive electrode layer. The battery was then placed in a button cell case and sealed with a sealing machine to form a button cell solid-state lithium metal battery. The structure of the assembled solid-state lithium metal battery is shown in Figure 1, and its electrochemical performance is shown in Figure 3.

[0065] The liquid electrolyte refers to an electrolyte obtained by mixing organic solvents ethylene carbonate (EC) and diethyl carbonate (DEC) in a mass ratio of 3:7, adding lithium hexafluorophosphate to dissolve and mixing evenly, and the concentration of lithium hexafluorophosphate is 1 mol / L.

[0066] Example 1-2 to Example 1-15

[0067] Except for adjusting the relevant preparation parameters according to Table 1, the rest is the same as Example 1-1.

[0068] Example 2-1 to Example 2-3

[0069] Except for adjusting the relevant preparation parameters according to Table 1, the rest is the same as Example 1-1.

[0070] Examples 2-4

[0071] <Preparation of Negative Electrode Layer>

[0072] A copper current collector with a thickness of 12 μm and a diameter of 12 mm was selected as the negative electrode current collector.

[0073] A layer with a thickness of t is deposited on the surface of the copper current collector facing the electrolyte layer by vacuum evaporation. 40 = 1 μm Zn layer as the metal layer, the metal layer was washed with deionized water to remove excess impurity ions on the surface, and then dried; then a layer of LiPAA (weight average molecular weight of 450000) aqueous solution was scraped on the surface of the metal layer not in contact with the copper current collector, and dried to a thickness of t 50 =1 μm lithiated polymer interface layer to obtain a LiPAA / Zn / Cu negative electrode layer (diameter of 12 mm).

[0074] The rest is the same as Example 1-1.

[0075] Example 2-5 to Example 2-7

[0076] Except for adjusting the relevant preparation parameters according to Table 2, the rest is the same as Example 2-4.

[0077] Examples 2-8

[0078] <Preparation of Electrolyte Layer>

[0079] Li 6.5 La3Zr 1.5 Ta 0.5 O 12 Oxide solid electrolyte sheet (diameter 14mm, thickness t 21 =1 mm) was polished to remove impurities such as LiCO3 and LiOH on the surface. A graphite layer with a thickness of 1 μm was scraped on the surface of the oxide solid electrolyte sheet facing the negative electrode layer using a graphite pencil (manufacturer: China First Pencil Co., Ltd., model: 10B) as a graphite modification layer (t 22 =1μm).

[0080] The rest is the same as Example 1-1.

[0081] Examples 2-9

[0082] Except for adjusting the relevant preparation parameters according to Table 2, the rest is the same as Example 1-1.

[0083] Comparative Example 1

[0084] <Preparation of positive electrode layer> and <Preparation of solid-state lithium metal battery> are the same as those in Example 1-1.

[0085] <Preparation of Negative Electrode Layer>

[0086] A copper current collector with a thickness of 12 μm and a diameter of 12 mm was selected as the negative electrode layer.

[0087] <Preparation of Electrolyte Layer>

[0088] Li 6.5 La3Za 1.5 Ta 0.5 O 12 Oxide solid electrolyte sheet (diameter 14mm, thickness t 21 =1 mm) was polished to remove impurities such as LiCO3 and LiOH on the surface to obtain an electrolyte layer.

[0089] Comparative Example 2

[0090] <Preparation of positive electrode layer>, <Preparation of negative electrode layer>, and <Preparation of solid-state lithium metal battery> are the same as those in Example 1-1.

[0091] <Preparation of Electrolyte Layer> is the same as Comparative Example 1.

[0092] Comparative Example 3

[0093] <Preparation of Negative Electrode Layer>

[0094] A copper current collector with a thickness of 12 μm and a diameter of 12 mm was selected as the negative electrode current collector.

[0095] A layer of LiPAA (weight average molecular weight 450,000) aqueous solution was scraped on the surface of the copper current collector facing the electrolyte layer and dried to a thickness of t 50 =1 μm lithiated polymer interface layer to obtain the LiPAA / Cu negative electrode layer (diameter of 12 mm).

[0096] <Preparation of positive electrode layer>, <Preparation of electrolyte layer>, and <Preparation of solid-state lithium metal battery> are the same as those in Example 1-1.

[0097] Comparative Example 4

[0098] <Preparation of Negative Electrode Layer>

[0099] A copper current collector with a thickness of 12 μm and a diameter of 12 mm was selected as the negative electrode current collector.

[0100] AgNO3 solution was added dropwise on the surface of the copper current collector facing the electrolyte layer to perform ion exchange and replace the t 40 = 1 μm thick Ag layer as the metal layer, the metal layer was washed with deionized water to remove excess impurity ions on the surface, and then dried to obtain an Ag / Cu negative electrode layer (diameter of 12 mm).

[0101] <Preparation of positive electrode layer>, <Preparation of electrolyte layer>, and <Preparation of solid-state lithium metal battery> are the same as those in Example 1-1.

[0102] The preparation parameters and performance parameters of each embodiment and comparative example are shown in Table 1 and Table 2.

[0103] Table 1 Note: “\” in Table 1 indicates no corresponding preparation parameters.

[0104] From Examples 1-1 to 1-15 and Comparative Examples 1 to 4, it can be seen that the solid-state lithium metal battery in the embodiment of the present application, by providing a graphite modified layer, a metal layer, and a lithiated polymer interface layer between the oxide solid electrolyte sheet and the negative electrode current collector, can reduce the possibility of solid-solid interface physical contact between the oxide solid electrolyte sheet and the negative electrode current collector, reduce the impedance of the solid-state lithium metal battery, and can also improve the problem of uneven lithium deposition, reducing the risk of short circuit of the solid-state lithium metal battery due to the growth of lithium dendrites. The solid-state lithium metal batteries of Examples 1-1 to 1-15 have higher first coulombic efficiency and capacity retention rate, indicating that the first coulombic efficiency and cycle performance of the solid-state lithium metal battery of the embodiment of the present application are improved. However, the solid-state lithium metal battery in Comparative Examples 1 to 4 does not provide at least one of a graphite modified layer, a metal layer, or a lithiated polymer interface layer between the oxide solid electrolyte sheet and the negative electrode current collector, and has a lower first coulombic efficiency and capacity retention rate, indicating that the solid-state lithium metal battery of the comparative example has a lower first coulombic efficiency and poorer cycle performance.

[0105] In addition, FIG3 shows a specific capacity-voltage test diagram of Example 1-1, FIG4 shows a cycle number-specific capacity-coulombic efficiency test diagram of Example 1-1 of the present application, and FIG5 shows a specific capacity-voltage test diagram of Comparative Example 1 of the present application. As can be seen from FIG3 and FIG4, Example 1-1 can be stably circulated with high coulombic efficiency in the voltage range of 2.0 to 4.2V, and the capacity remains very stable; as can be seen from FIG5, the voltage of the solid-state lithium metal battery of Comparative Example 1 quickly exceeds the 4.2V cut-off potential after charging, reaching the protection voltage of the test equipment 5V, and cannot circulate normally. The curve is abnormal. This is because the solid-state lithium metal battery of Comparative Example 1 does not have a graphite modification layer, a metal layer, and a lithiated polymer interface layer between the oxide solid electrolyte sheet and the negative electrode current collector. The interface contact on the negative electrode side is poor, and the interface impedance is too large to cause the inability to work normally and show an abnormal curve phenomenon (excessive polarization will cause the solid-state lithium metal battery voltage to be quickly charged to a 4.2V cut-off voltage, which is shown as a vertical straight line in the figure).

[0106] The thickness of the graphite modification layer typically affects the initial coulombic efficiency and cycling performance of solid-state lithium metal batteries. As can be seen from Examples 1-1 to 1-5, solid-state lithium metal batteries with a graphite modification layer thickness within the range of this application exhibit high initial coulombic efficiency and capacity retention, indicating that solid-state lithium metal batteries have good initial coulombic efficiency and cycling performance.

[0107] The thickness of the metal layer generally affects the initial coulombic efficiency and cycling performance of solid-state lithium metal batteries. As can be seen from Examples 1-1 to 1-3, 1-6, and 1-7, solid-state lithium metal batteries with metal layer thicknesses within the range of this application exhibit high initial coulombic efficiency and capacity retention, indicating that solid-state lithium metal batteries have good initial coulombic efficiency and cycling performance.

[0108] The thickness of the lithiated polymer interface layer typically affects the initial coulombic efficiency and cycling performance of solid-state lithium metal batteries. As can be seen from Examples 1-1 to 1-3, and 1-8 to 1-10, solid-state lithium metal batteries with a lithiated polymer interface layer thickness within the range of this application exhibit high initial coulombic efficiency and capacity retention, demonstrating that solid-state lithium metal batteries have good initial coulombic efficiency and cycling performance.

[0109] The thickness of the oxide solid electrolyte sheet typically affects the initial coulombic efficiency and cycling performance of solid-state lithium metal batteries. As can be seen from Examples 1-1, 1-11, and 1-12, solid-state lithium metal batteries using oxide solid electrolyte sheet thicknesses within the range of this application exhibit high initial coulombic efficiency and capacity retention, demonstrating that solid-state lithium metal batteries have good initial coulombic efficiency and cycling performance.

[0110] Table 2

[0111] The material type of the lithiated polymer interface layer typically affects the initial coulombic efficiency (ICE) and cycling performance of solid-state lithium metal batteries. As can be seen from Examples 1-1, 2-1, and 2-3, solid-state lithium metal batteries using a lithiated polymer interface layer material within the scope of this application exhibit high initial coulombic efficiency (ICE) and capacity retention, demonstrating that solid-state lithium metal batteries have good initial coulombic efficiency and cycling performance.

[0112] The material type of the metal layer generally affects the initial coulombic efficiency and cycling performance of solid-state lithium metal batteries. As can be seen from Examples 1-1, 2-4, and 2-7, solid-state lithium metal batteries using metal layer materials within the scope of this application exhibit high initial coulombic efficiency and capacity retention, indicating that solid-state lithium metal batteries have good initial coulombic efficiency and cycling performance.

[0113] The material type of the graphite-modified layer typically affects the initial coulombic efficiency and cycling performance of solid-state lithium metal batteries. As can be seen from Examples 1-1 and 2-8, solid-state lithium metal batteries using graphite-modified layers with materials within the scope of this application exhibit high initial coulombic efficiency and capacity retention, demonstrating that solid-state lithium metal batteries have good initial coulombic efficiency and cycling performance.

[0114] The material type of the oxide solid electrolyte sheet typically affects the initial coulombic efficiency and cycling performance of solid-state lithium metal batteries. As can be seen from Examples 1-1 and 2-9, solid-state lithium metal batteries using oxide solid electrolyte sheets made from materials within the scope of this application exhibit high initial coulombic efficiency and capacity retention, demonstrating that solid-state lithium metal batteries have good initial coulombic efficiency and cycling performance.

[0115] It should be noted that, in this article, the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements that are inherent to such process, method, article or apparatus.

[0116] Each embodiment in this specification is described in a related manner. The same or similar parts between the embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments.

[0117] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A solid-state lithium metal battery, which includes a positive electrode layer, a negative electrode current collector, and an electrolyte layer disposed between the positive electrode layer and the negative electrode current collector; The positive electrode layer includes a positive electrode current collector and a positive electrode active material layer, and the positive electrode active material layer is disposed on the surface of the positive electrode current collector facing the electrolyte layer; The electrolyte layer includes an oxide solid electrolyte sheet and a graphite modification layer, and the graphite modification layer is disposed on the surface of the oxide solid electrolyte sheet facing the negative electrode current collector; A metal layer and a lithiated polymer interface layer are disposed on the surface of the negative electrode current collector facing the electrolyte layer, and the metal layer is located between the negative electrode current collector and the lithiated polymer interface layer.

2. The solid-state lithium metal battery according to claim 1, wherein, The negative electrode current collector is selected from a copper current collector; The material of the metal layer includes at least one of aluminum, silver, zinc, silicon, or tin.

3. The solid-state lithium metal battery according to claim 1, wherein, The material of the lithiated polymer interface layer includes at least one of lithium poly(acrylate), lithium carboxymethyl cellulose, lithium alginate, or lithium polymethyl methacrylate.

4. The solid-state lithium metal battery according to claim 1, wherein, The material of the graphite modification layer is Li x C 6 , 0≤x≤1.

5. The solid-state lithium metal battery according to claim 1, wherein, The material of the oxide solid electrolyte sheet includes at least one of the following compounds: NASICON structure of lithium germanium aluminum phosphate 1+x1 Al x1 Ge 2-x1 (PO 4 ) 3 or its isomorphous heteroatom doped compound, lithium aluminum titanium phosphate Li 1+x2 Al x2 Ti 2-x2 (PO 4 ) 3 Or its isomorphous heteroatom doped compound, lanthanum titanate lithium Li with perovskite structure 3x3 L a2 / 3-x3 TiO 3 or its isomorphous heteroatom doped compound, garnet structured lithium lanthanum zirconium oxide Li 7-x4 La 3 Zr 2-x4 O 12 or its isomorphous heteroatom doped compounds, antiperovskite structured Li 3-2x5 M x5 HalO, Li 3 OCl or its isomorphous heteroatom doped compounds, Li with LISICON structure 4-x6 Si 1-x6 P x6 O 4 or its isomorphous heteroatom doped compound, Li 14 ZnGe 4 O 16 or an isomorphous heteroatom-doped compound thereof; where 0 < x1 ≤ 0.75, 0 < x2 ≤ 0.5, 0.06 ≤ x3 ≤ 0.14, 0 ≤ x4 < 1, 0 ≤ x5 ≤ 0.01, 0.5 ≤ x6 ≤ 0.6, Hal is the element Cl or I, and the heteroatoms of each compound are independently selected from at least one of Al, Ta, Nb, Ti, Ge, F, Br, or V.

6. The solid-state lithium metal battery according to claim 1, wherein, The thickness of the metal layer is 0.1 μm to 5 μm.

7. The solid-state lithium metal battery according to claim 6, wherein, The thickness of the metal layer is 1 μm to 3 μm.

8. The solid-state lithium metal battery according to claim 1, wherein, The thickness of the lithiated polymer interface layer is 0.1 μm to 5 μm.

9. The solid-state lithium metal battery according to claim 8, wherein, The thickness of the lithiated polymer interface layer is 1 μm to 3 μm.

10. The solid-state lithium metal battery according to claim 1, wherein, The thickness of the graphite modification layer is 0.1 μm to 5 μm.

11. The solid-state lithium metal battery according to claim 10, wherein, The thickness of the graphite modification layer is 1 μm to 3 μm.

12. The solid-state lithium metal battery according to claim 1, wherein, The thickness of the oxide solid electrolyte sheet is 0.01 mm to 1 mm.

13. An electronic device, which includes the solid-state lithium metal battery according to any one of claims 1 to 12.

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