All-solid-state battery and preparation method thereof
By using a composite solid electrolyte membrane in an all-solid state battery, the first solid electrolyte reacts with the lithium negative electrode to generate the second solid electrolyte layer, the problem of poor compatibility between the solid electrolyte and the lithium negative electrode is solved, and efficient lithium ion transmission and battery performance improvement is achieved.
Patent Information
- Application Number
- CN202510524481.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-24
- Publication Date
- 2025-08-08
AI Technical Summary
In all-solid-state batteries, the solid electrolyte has poor compatibility with the lithium negative electrode and is easy to decompose, resulting in interface problems and the inability to use the battery.
A composite solid electrolyte membrane is used to react the first solid electrolyte with the lithium negative electrode to form a second solid electrolyte layer to form a chemically stable interface. The second solid electrolyte layer acts as a passivation layer to prevent further reactions, and the interface contact performance is improved through Young's modulus difference.
It improves lithium ion transmission performance, reduces battery internal resistance, inhibits lithium dendrites growth, prevents battery short circuit, and improves battery circulation and fast charging performance.
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Abstract
Description
Technical Field
[0001] The present application relates to the field of battery technology, and in particular to an all-solid-state battery and a preparation method thereof. Background Art
[0002] In all-solid-state batteries, since solid electrolytes are used instead of electrolytes, there is solid-solid contact between the solid electrolyte membrane and the positive and negative electrodes, resulting in obvious interface problems. Moreover, most solid electrolytes have poor compatibility with lithium-containing negative electrodes and are prone to decomposition, making the battery unusable. Summary of the Invention
[0003] Based on this, the present application provides an all-solid-state battery and an electrical device to solve the above technical problems.
[0004] A first aspect of the present application provides an all-solid-state battery, comprising a positive electrode, a lithium-containing negative electrode, and a composite solid electrolyte membrane disposed therebetween, wherein the composite solid electrolyte membrane comprises a first solid electrolyte layer and a second solid electrolyte layer, wherein the first solid electrolyte layer and the second solid electrolyte layer respectively comprise a first solid electrolyte and a second solid electrolyte;
[0005] The second solid electrolyte is generated by the reaction of the first solid electrolyte and the lithium-containing negative electrode, and the second solid electrolyte does not react with the lithium-containing negative electrode;
[0006] The lithium-containing negative electrode includes a lithium metal negative electrode or a lithium alloy negative electrode.
[0007] In some embodiments, the first solid electrolyte comprises Li a1 P b1 S c1 O d1 Cl e1 F f1 , among which, a1+5b1=2c1+2d1+e1+f1, 4≤a1≤7, 0.8≤b1≤1.3, 2≤c1≤6, 0<d1≤3, 0<e1≤2, 0<f1≤2.
[0008] In some embodiments, the first solid electrolyte comprises Li a2 P b2 S c2 O d2 Cl e2 , among which, a2+5b2=2c2+2d2+e2, 4≤a2≤7, 0.8≤b2≤1.3, 2≤c2≤6, 0<d2≤3, 0<e2≤4.
[0009] In some embodiments, the Young's modulus of the first solid electrolyte layer is lower than the Young's modulus of the second solid electrolyte layer.
[0010] In some embodiments, the Young's modulus of the first solid electrolyte layer is 5 GPa to 40 GPa.
[0011] In some embodiments, the Young's modulus of the second solid electrolyte layer is 40 GPa to 200 GPa.
[0012] In some embodiments, the second solid electrolyte layer includes Li2O and / or LiF.
[0013] In some embodiments, the composite solid electrolyte membrane further includes a third solid electrolyte layer, which is disposed on a side of the first solid electrolyte layer close to the positive electrode, and has a Young's modulus of less than 50 GPa.
[0014] The second aspect of the present application provides a method for preparing an all-solid-state battery as described in the first aspect, comprising the following steps:
[0015] S1. Roll-pressing the first solid electrolyte to obtain a first solid electrolyte layer;
[0016] S2. Laying a lithium-containing negative electrode on the other side of the first solid electrolyte layer, and laying a positive electrode on the other side of the first solid electrolyte layer, or laying a third solid electrolyte layer and a positive electrode on the other side of the first solid electrolyte layer, and then rolling the layers to produce an all-solid-state battery;
[0017] The first solid electrolyte in the first solid electrolyte layer reacts with the lithium-containing negative electrode to generate a second solid electrolyte for forming the second solid electrolyte layer.
[0018] In some embodiments, in step S2, the rolling pressure is 100 MPa to 500 MPa.
[0019] This application involves a first solid electrolyte reacting with lithium to form a second solid electrolyte. This second solid electrolyte does not react with the lithium negative electrode. This second solid electrolyte layer is generated through an in-situ reaction between the first solid electrolyte layer and the lithium-containing negative electrode, forming a chemically stable interface. The second solid electrolyte layer acts as a passivation layer, preventing further reaction between the negative electrode and the first solid electrolyte. This solves the problems of electrolyte decomposition and increased interfacial impedance caused by continuous side reactions when a conventional lithium metal negative electrode and solid electrolyte are in direct contact.
[0020] Furthermore, compared with traditional composite solid electrolyte membranes, there is no obvious interface between the first solid electrolyte layer and the second solid electrolyte layer in the composite solid electrolyte membrane of the present application, which improves the lithium ion transmission performance and reduces the internal resistance of the battery.
[0021] At the same time, the mechanical strength of the first solid electrolyte layer is lower than that of the second solid electrolyte layer. The first solid electrolyte layer with smaller mechanical strength is in contact with the positive electrode, which effectively improves the interface contact performance between the composite solid electrolyte membrane and the positive electrode; the second solid electrolyte layer with larger mechanical strength is in contact with the negative electrode, which effectively inhibits the growth of lithium dendrites on the negative electrode side, prevents lithium dendrites from piercing the composite solid electrolyte membrane, and prevents battery short circuit. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following briefly introduces the drawings required for use in the embodiments or related technical descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0023] Figure 1 This is a process diagram for the preparation of all-solid-state batteries in some embodiments of the present application. DETAILED DESCRIPTION
[0024] Reference will now be made to embodiments of the present application in detail, one or more examples of which are described below. Each example is provided to illustrate, but not to limit, the present application. Indeed, it will be apparent to those skilled in the art that various modifications and variations may be made to the present application without departing from the scope or spirit of the present application. For example, features illustrated or described as part of one embodiment may be used in another embodiment to produce further embodiments.
[0025] Therefore, it is intended that this application covers such modifications and variations that fall within the scope of the appended claims and their equivalents. Other objects, features, and aspects of the present application are disclosed in or are apparent from the following detailed description. Those skilled in the art will appreciate that this discussion is merely a description of exemplary embodiments and is not intended to limit the broader aspects of the present application.
[0026] In this application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.
[0027] In this application, when referring to numerical ranges, unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges subsumed therein.
[0028] In this document, when referring to a range, if the unit is followed only by the right endpoint, it means that the units of the left and right endpoints are the same. For example, 100~150 nm means that the units of the left endpoint "100" and the right endpoint "150" are both nm (nanometers).
[0029] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.
[0030] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.
[0031] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, a statement that a method includes steps (a) and (b) indicates that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, a statement that a method may also include step (c) indicates that step (c) may be added to the method in any order, for example, the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.
[0032] Unless otherwise specified, the terms "include" and "comprising" used in this application may be open-ended or closed-ended. For example, "include" and "comprising" may indicate that other components not listed may also be included or that only the listed components are included.
[0033] Unless otherwise specified, the term "or" is used in this application to be inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied if any of the following conditions are met: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).
[0034] As mentioned above, traditional solid-state electrolytes cannot be used in all-solid-state batteries with lithium metal and / or lithium alloys as negative electrodes because they easily react continuously with lithium metal and lithium alloys.
[0035] The first aspect of the present application provides an all-solid-state battery, comprising a positive electrode, a lithium-containing negative electrode, and a composite solid-state electrolyte membrane disposed therebetween, wherein the composite solid-state electrolyte membrane comprises a first solid-state electrolyte layer and a second solid-state electrolyte layer, wherein the first solid-state electrolyte layer and the second solid-state electrolyte layer respectively comprise a first solid-state electrolyte and a second solid-state electrolyte; wherein the second solid-state electrolyte is generated by the reaction of the first solid-state electrolyte and the lithium-containing negative electrode, and the second solid-state electrolyte does not react with the lithium-containing negative electrode.
[0036] The lithium-containing negative electrode includes a lithium metal negative electrode or a lithium alloy negative electrode.
[0037] Illustratively, the lithium alloy may be one of an aluminum-lithium alloy, a lithium-tin alloy, a lithium-lead alloy, and a lithium-silicon alloy.
[0038] The first solid electrolyte reacts with lithium to form a second solid electrolyte. This second solid electrolyte does not react with the lithium anode. This second solid electrolyte layer is generated through an in-situ reaction between the first solid electrolyte layer and the lithium-containing anode, forming a chemically stable interface. This second solid electrolyte layer acts as a passivation layer, preventing further reaction between the anode and the first solid electrolyte. This solves the problems of electrolyte decomposition and increased interfacial impedance caused by continuous side reactions when direct contact between traditional lithium metal anodes and solid electrolytes occurs.
[0039] In some embodiments, the first solid electrolyte comprises Li a1 P b1 S c1 O d1 Cl e1 F f1 , among which, a1+5b1=2c1+2d1+e1+f1, 4≤a1≤7, 0.8≤b1≤1.3, 2≤c1≤6, 0<d1≤3, 0<e1≤2, 0<f1≤2.
[0040] In some embodiments, the first solid electrolyte comprises Li a2 P b2 S c2 O d2 Cl e2 , among which, a2+5b2=2c2+2d2+e2, 4≤a2≤7, 0.8≤b2≤1.3, 2≤c2≤6, 0<d2≤3, 0<e2≤4.
[0041] In some embodiments, the first solid electrolyte contains a lithium-containing negative electrode that reacts to form a second solid electrolyte, and the second solid electrolyte includes Li2O and / or LiF.
[0042] In some embodiments, the Young's modulus of the first solid electrolyte layer is lower than the Young's modulus of the second solid electrolyte layer.
[0043] On the one hand, the second solid electrolyte layer has a higher Young's modulus and greater mechanical strength. When placed on the negative electrode side, it effectively inhibits the growth of lithium dendrites on the negative electrode side, preventing them from piercing the composite solid electrolyte membrane and preventing battery short circuits. The first solid electrolyte layer has a lower Young's modulus and a softer texture, which effectively cooperates with the positive electrode and improves the interfacial contact between the electrolyte layer and the positive electrode.
[0044] Moreover, since the Young's modulus of the second solid electrolyte layer is relatively high, it is not easy to repeatedly break / rebuild during the cycle, resulting in the consumption of lithium and electrolyte, which is beneficial to improving the cycle performance of the battery.
[0045] On the other hand, the second solid electrolyte layer is generated in situ by the first solid electrolyte layer and the lithium negative electrode, which can effectively avoid the interface contact problem between the first solid electrolyte layer and the second solid electrolyte layer and the interface contact problem between the entire composite solid electrolyte membrane and the negative electrode.
[0046] In some embodiments, the Young's modulus of the first solid electrolyte layer is 5 GPa to 40 GPa, including but not limited to 5 GPa, 8 GPa, 10 GPa, 15 GPa, 18 GPa, 20 GPa, 25 GPa, 30 GPa, 32 GPa, 35 GPa, 38 GPa, and 40 GPa.
[0047] In some embodiments, the Young's modulus of the second solid electrolyte layer is 40 GPa to 200 GPa, including but not limited to 40 GPa, 50 GPa, 55 GPa, 60 GPa, 65 GPa, 70 GPa, 75 GPa, 90 GPa, 100 GPa, 120 GPa, 140 GPa, 160 GPa, 180 GPa, and 200 GPa.
[0048] In some embodiments, the ionic conductivity λ1 of the first solid electrolyte layer is 0.5 mS / cm~10 mS / cm, including but not limited to 0.5 mS / cm, 1.5 mS / cm, 2.5 mS / cm, 3.5 mS / cm, 4.5 mS / cm, 5.5 mS / cm, 6.5 mS / cm, 7.5 mS / cm, 8.5 mS / cm, and 10 mS / cm.
[0049] This application constructs a first solid electrolyte layer with high ionic conductivity as the main functional layer, which can effectively improve the lithium ion transmission efficiency of the composite solid electrolyte membrane, thereby effectively enhancing the fast charging performance of the battery. Moreover, the first solid electrolyte layer close to the negative electrode side can generate a second solid electrolyte layer in situ. This structure not only maintains high ion conductivity characteristics, but also achieves stabilization of the electrode / electrolyte interface, so that the composite solid electrolyte membrane has both excellent ion conductivity and good interface compatibility, and ultimately achieves a significant improvement in the overall performance of the battery.
[0050] In some embodiments, the thickness of the first solid electrolyte layer is 5 μm to 200 μm, including but not limited to 5 μm, 10 μm, 20 μm, 40 μm, 60 μm, 80 μm, 100 μm, 120 μm, 140 μm, 160 μm, 180 μm, and 200 μm.
[0051] In some embodiments, the thickness of the first solid electrolyte layer is greater than the thickness of the second solid electrolyte layer. This may be because the second solid electrolyte does not react with the negative electrode, effectively preventing the negative electrode from reacting with the first solid electrolyte. Therefore, the thickness of the second solid electrolyte does not continue to increase. The above is merely the applicant's possible speculation on the reaction mechanism and does not constitute a limitation on the scope of protection of this application.
[0052] In some embodiments, the composite solid electrolyte membrane further includes a third solid electrolyte layer, which is disposed on a side of the first solid electrolyte layer close to the positive electrode, and has a Young's modulus of less than 50 GPa.
[0053] In some embodiments, the third solid electrolyte layer includes a third solid electrolyte.
[0054] In some embodiments, the third solid electrolyte is a halide solid electrolyte.
[0055] Exemplarily, the third solid electrolyte includes one or more of Li2ZrCl6 and its derivatives, Li3InCl6 and its derivatives, Li3YCl6 and its derivatives, etc. It is understood that the derivatives here refer to halide solid electrolytes prepared by doping or the like.
[0056] Such as Li 2.4 Zr 0.7 Eu 0.2 Mg 0.1 Cl5F1、Li 2.07 Zr 0.83 Dy 0.12 Nb 0.05 Cl 5.8 F 0.2 、Li2ZrCl5O 0.5 、Li3InCl5Br、Li3In 0.9 Sc 0.1 Cl6、Li3YCl3Br3、Li3Y 0.8 Al 0.2 Cl6 etc.
[0057] In some embodiments, the first solid electrolyte layer further includes a binder.
[0058] It is understandable that, in the present application, there is no particular limitation on the type of adhesive, and any known adhesive can be used in the present application without violating the inventive concept of the present application.
[0059] As an illustrative example only and not a limitation of the scope of protection, the binder includes but is not limited to one or more of polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyvinylidene fluoride hexafluoropropylene (PVDF-HFP), polypropylene (PP), polyethylene (PE), styrene-butadiene rubber (SBR), nitrile rubber (NBR), sodium carboxymethyl cellulose (CMC), polyacrylic acid, polyacrylonitrile, and sodium alginate.
[0060] It is understandable that the first solid electrolyte layer may also include conventional additives. Without violating the inventive concept of this application, this application does not specifically limit the types and amounts of conventional additives. Adjustments to the types and amounts of conventional additives based on conventional purposes should be considered within the scope of protection of this application.
[0061] In some embodiments, in the first solid electrolyte layer, the mass proportion of the binder is 0-10 wt %, preferably, the mass proportion of the binder is 0.1 wt %-5 wt %, more preferably, the mass proportion of the binder is 0.5 wt %-3 wt %.
[0062] In some embodiments, the positive electrode includes a positive electrode layer, the positive electrode layer includes a positive electrode active material, the positive electrode active material includes but is not limited to LiCoO2, LiMnO2, LiNiO2, LiVO2, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiMn2O4, LiTi5O 12 、Li(Ni 0.5 Mn 1.5 )O4, LiFePO4, LiMnPO4, LiNiPO4, LiCoPO4, LiNbO3 or any one or a combination of at least two of sulfur-carbon composite materials. Among them, LiCoO2, LiMnO2, LiNiO2, LiVO2 and LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 has a rock salt layered structure, LiMn2O4, LiTi5O 12 and Li(Ni 0.5 Mn 1.5 )O4 has a spinel structure, LiFePO4, LiMnPO4, LiNiPO4, LiCoPO4 and LiNbO3 have an olivine structure. Without violating the inventive concept of this application, any known positive electrode active material can be used in this application.
[0063] In some embodiments, the positive electrode further includes a positive electrode conductor, a positive electrode binder, and a positive electrode current collector.
[0064] The positive electrode conductive material is mainly used to assist and improve the conductivity in the secondary battery, and there is no particular limitation on it in the embodiments of the present application, as long as it has conductivity without causing chemical changes.
[0065] The following are merely examples of positive electrode conductive agents including graphite, such as natural graphite or artificial graphite; carbon materials, such as super-P, acetylene black, Ketjen black, channel black, furnace black, lamp black and thermal black; conductive fibers, such as carbon fibers and metal fibers; conductive tubes, such as carbon nanotubes; metal powders, such as fluorocarbon powder, aluminum powder and nickel powder; conductive whiskers, such as zinc oxide and potassium titanate; conductive metal oxides, such as titanium oxide; and polyphenylene derivatives, and from the aspect of improving conductivity, the positive electrode conductive agent may preferably be carbon black.
[0066] In some embodiments, the positive electrode binder includes, but is not limited to, a fiberized binder. The fiberized binder includes one or more of polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyvinylidene fluoride hexafluoropropylene, polypropylene, polyethylene, and polyimide. It is used to bond components such as the positive electrode active material, the positive electrode conductive material, and the positive electrode current collector together.
[0067] In some embodiments, the positive electrode current collector is not particularly limited as long as it has conductivity and does not cause chemical changes in the battery. Specifically, copper, stainless steel, aluminum, nickel, titanium, or a metal current collector with a surface treated with carbon or other substances can be used.
[0068] It should be understood that the above examples of positive and negative electrodes are merely illustrative. Any known positive electrode active material, positive electrode binder, positive electrode conductive agent, positive electrode current collector, and negative electrode current collector may be used in this application without violating the inventive concept of this application. Furthermore, the addition of known additives based on actual usage requirements should also be considered within the scope of protection of this application.
[0069] In some embodiments, the positive electrode further comprises a solid electrolyte.
[0070] In some embodiments, the solid electrolyte included in the positive electrode is a first solid electrolyte.
[0071] The present application adds a first solid electrolyte to the positive electrode and the first solid electrolyte layer in contact therewith at the same time, so that the interface between the positive electrode and the first solid electrolyte layer can be better contacted, thereby reducing the obstruction of ion transmission at the interface, reducing the interface resistance, and increasing the migration rate of lithium ions between the positive electrode and the solid electrolyte membrane, thereby improving the charge and discharge efficiency of the battery.
[0072] At the same time, adding the first solid electrolyte to the positive electrode can fill the gaps between the positive electrode active materials, relieve the stress caused by the volume change of the positive electrode active materials during charging and discharging, enhance the structural stability of the positive electrode, and improve the cycle performance of the battery.
[0073] In some embodiments, the solid electrolyte included in the positive electrode is a third solid electrolyte. It is understood that when the positive electrode includes the first solid electrolyte, the first solid electrolyte layer or the third solid electrolyte layer may be disposed near the positive electrode side. Similarly, when the positive electrode includes the third solid electrolyte, the first solid electrolyte layer or the third solid electrolyte layer may be disposed near the positive electrode side.
[0074] Second, as Figure 1 As shown, the present application provides a method for preparing an all-solid-state battery, comprising the following steps:
[0075] S1. Roll-pressing the first solid electrolyte to obtain a first solid electrolyte layer;
[0076] S2. Laying a lithium-containing negative electrode on one side of the first solid electrolyte layer and a positive electrode on the other side of the first solid electrolyte layer, or laminating a third solid electrolyte layer and a positive electrode on the other side of the first solid electrolyte layer, and performing roll pressing to produce an all-solid-state battery;
[0077] The first solid electrolyte in the first solid electrolyte layer reacts with the lithium-containing negative electrode to form a second solid electrolyte, which is used to form the second solid electrolyte layer. It is understandable that because the first solid electrolyte layer and the lithium-containing negative electrode are both relatively soft, roller pressing can effectively increase the contact area between the first solid electrolyte layer and the lithium-containing negative electrode, which is conducive to the formation of the second solid electrolyte layer and improves the density.
[0078] In some embodiments, the rolling pressure is 100 MPa to 500 MPa.
[0079] The present application will be further described below with reference to specific embodiments and comparative examples.
[0080] Example 1
[0081] Preparation of positive electrode:
[0082] The positive electrode active material LiNi 0.8Co 0.1 Mn 0.1 O2 (NCM811), positive electrode binder PTFE, positive electrode conductive agent super-P and solid electrolyte Li6PS 2.5 O₂ClF₂ was uniformly mixed in a mass ratio of 70:3:2:25 and placed in a high-shear mixer for fiberization to form a first mixture. This first mixture was then roller-pressed to form a positive electrode layer at a temperature of 60°C for 5 minutes. The positive electrode layer was then laminated with the positive electrode current collector aluminum foil to produce the positive electrode.
[0083] Negative electrode: lithium sheet.
[0084] Preparation of the first solid electrolyte layer:
[0085] The first solid-state electrolyte Li6PS 2.5 O2ClF was roll-pressed at a pressure of 400 MPa to obtain the first solid electrolyte layer.
[0086] Among them, the Young's modulus of the first solid electrolyte layer is 30 GPa, the thickness is 50 μm, and the ionic conductivity λ1 is 2.75 mS / cm.
[0087] Preparation of all-solid-state batteries:
[0088] A positive electrode is attached to one side of the first solid electrolyte layer, and a lithium sheet is attached to the other side of the first solid electrolyte layer. An all-solid-state battery is produced after rolling under a pressure of 200 MPa.
[0089] The first solid electrolyte in the first solid electrolyte layer reacts with the lithium sheet to form a second solid electrolyte layer. The Young's modulus of the second solid electrolyte layer is 120 GPa, and the second solid electrolyte layer includes LiF and Li2O.
[0090] Example 2
[0091] The difference between this embodiment and embodiment 1 is the thickness of the first solid electrolyte layer. The details are as follows:
[0092] Preparation of positive electrode:
[0093] The positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811), positive electrode binder PTFE, positive electrode conductive agent super-P and solid electrolyte Li6PS 2.5O₂ClF₂ was uniformly mixed in a mass ratio of 70:3:2:25 and placed in a high-shear mixer for fiberization to form a first mixture. This first mixture was then roller-pressed to form a positive electrode layer at a temperature of 60°C for 5 minutes. The positive electrode layer was then laminated with the positive electrode current collector aluminum foil to produce the positive electrode.
[0094] Negative electrode: lithium sheet.
[0095] Preparation of the first solid electrolyte layer:
[0096] The first solid-state electrolyte Li6PS 2.5 O2ClF was roll-pressed at a pressure of 400 MPa to obtain the first solid electrolyte layer.
[0097] Among them, the Young's modulus of the first solid electrolyte layer is 30 GPa, the thickness is 10 μm, and the ionic conductivity λ1 is 2.75 mS / cm.
[0098] Preparation of all-solid-state batteries:
[0099] A positive electrode is attached to one side of the first solid electrolyte layer, and a lithium sheet is attached to the other side of the first solid electrolyte layer. An all-solid-state battery is produced after rolling under a pressure of 200 MPa.
[0100] The first solid electrolyte in the first solid electrolyte layer reacts with the lithium sheet to form a second solid electrolyte layer. The Young's modulus of the second solid electrolyte layer is 120 GPa, and the second solid electrolyte layer includes LiF and Li2O.
[0101] Example 3
[0102] The difference between this embodiment and embodiment 1 is the thickness of the first solid electrolyte layer. The details are as follows:
[0103] Preparation of positive electrode:
[0104] The positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811), positive electrode binder PTFE, positive electrode conductive agent super-P and solid electrolyte Li6PS 2.5 O₂ClF₂ was uniformly mixed in a mass ratio of 70:3:2:25 and placed in a high-shear mixer for fiberization to form a first mixture. This first mixture was then roller-pressed to form a positive electrode layer at a temperature of 60°C for 5 minutes. The positive electrode layer was then laminated with the positive electrode current collector aluminum foil to produce the positive electrode.
[0105] Negative electrode: lithium sheet.
[0106] Preparation of the first solid electrolyte layer:
[0107] The first solid-state electrolyte Li6PS 2.5 O2ClF was roll-pressed at a pressure of 400 MPa to obtain the first solid electrolyte layer.
[0108] The Young's modulus of the first solid electrolyte layer is 30 GPa, the thickness is 200 μm, and the ionic conductivity λ1 is 2.75 mS / cm.
[0109] Preparation of all-solid-state batteries:
[0110] A positive electrode is attached to one side of the first solid electrolyte layer, and a lithium sheet is attached to the other side of the first solid electrolyte layer. An all-solid-state battery is produced after rolling under a pressure of 200 MPa.
[0111] The first solid electrolyte in the first solid electrolyte layer reacts with the lithium sheet to form a second solid electrolyte layer. The Young's modulus of the second solid electrolyte layer is 120 GPa, and the second solid electrolyte layer includes LiF and Li2O.
[0112] Example 4
[0113] The difference between this embodiment and embodiment 1 is that a different first solid electrolyte is used. The details are as follows:
[0114] Preparation of positive electrode:
[0115] The positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811), positive electrode binder PTFE, positive electrode conductive agent super-P and solid electrolyte Li5PS 2.5 O 1.75 Cl 1.5 The mixture was uniformly mixed in a mass ratio of 70:3:2:25 and placed in a high-shear mixer for fiberization to form a first mixture. The first mixture was then roll-pressed to form a positive electrode layer at a temperature of 60°C for 5 minutes. The positive electrode layer and the positive electrode current collector aluminum foil were then laminated together to form a positive electrode.
[0116] Negative electrode: lithium sheet.
[0117] Preparation of the first solid electrolyte layer:
[0118] The first solid-state electrolyte Li5PS 2.5 O 1.75 Cl 1.5 The first solid electrolyte layer was obtained by roll pressing at a pressure of 400 MPa.
[0119] Among them, the Young's modulus of the first solid electrolyte layer is 37 GPa, the thickness is 50 μm, and the ionic conductivity λ1 is 4.36 mS / cm.
[0120] Preparation of all-solid-state batteries:
[0121] A positive electrode is attached to one side of the first solid electrolyte layer, and a lithium sheet is attached to the other side of the first solid electrolyte layer. An all-solid-state battery is produced after rolling under a pressure of 200 MPa.
[0122] The first solid electrolyte in the first solid electrolyte layer reacts with the lithium sheet to generate a second solid electrolyte layer. The Young's modulus of the second solid electrolyte layer is 130 GPa, and the second solid electrolyte layer includes Li2O.
[0123] Example 5
[0124] The difference between this embodiment and embodiment 1 is that a different first solid electrolyte is used. The details are as follows:
[0125] Preparation of positive electrode:
[0126] The positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811), positive electrode binder PTFE, positive electrode conductive agent super-P and solid electrolyte Li6PS 2.5 O2Cl 1.5 F 0.5 The mixture was uniformly mixed in a mass ratio of 70:3:2:25 and placed in a high-shear mixer for fiberization to form a first mixture. The first mixture was then roll-pressed to form a positive electrode layer at a temperature of 60°C for 5 minutes. The positive electrode layer and the positive electrode current collector aluminum foil were then laminated together to form a positive electrode.
[0127] Negative electrode: lithium sheet.
[0128] Preparation of the first solid electrolyte layer:
[0129] The first solid-state electrolyte Li6PS 2.5 O2Cl 1.5 F 0.5 The first solid electrolyte layer was obtained by roll pressing at a pressure of 400 MPa.
[0130] The Young's modulus of the first solid electrolyte layer is 34 GPa, the thickness is 50 μm, and the ionic conductivity λ1 is 3.68 mS / cm.
[0131] Preparation of all-solid-state batteries:
[0132] A positive electrode is attached to one side of the first solid electrolyte layer, and a lithium sheet is attached to the other side of the first solid electrolyte layer. An all-solid-state battery is produced after rolling under a pressure of 200 MPa.
[0133] The first solid electrolyte in the first solid electrolyte layer reacts with the lithium sheet to form a second solid electrolyte layer. The Young's modulus of the second solid electrolyte layer is 124 GPa, and the second solid electrolyte layer includes LiF and Li2O.
[0134] Example 6
[0135] Preparation of positive electrode:
[0136] The positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811), positive electrode binder PTFE, positive electrode conductive agent super-P and solid electrolyte Li6PS 2.5 O₂ClF₂ was uniformly mixed in a mass ratio of 70:3:2:25 and placed in a high-shear mixer for fiberization to form a first mixture. This first mixture was then roller-pressed to form a positive electrode layer at a temperature of 60°C for 5 minutes. The positive electrode layer was then laminated with the positive electrode current collector aluminum foil to produce the positive electrode.
[0137] Negative electrode: lithium-indium alloy.
[0138] Preparation of the first solid electrolyte layer:
[0139] The first solid-state electrolyte Li6PS 2.5 O2ClF and binder PVDF were mixed in a mass ratio of 99.9:0.1 and then roller pressed under a pressure of 400 MPa to obtain a first solid electrolyte layer.
[0140] Among them, the Young's modulus of the first solid electrolyte layer is 30 GPa, the thickness is 5 μm, and the ionic conductivity λ1 is 2.75 mS / cm.
[0141] Preparation of the third solid electrolyte layer:
[0142] The third solid electrolyte Li2ZrCl6 and the binder PVDF were mixed in a mass ratio of 99.9:0.1 and then roller pressed under a pressure of 400 MPa to obtain a third solid electrolyte layer with a thickness of 50 μm.
[0143] Preparation of all-solid-state batteries:
[0144] A third solid electrolyte layer is attached to one side of the first solid electrolyte layer, a positive electrode is attached to the other side of the third solid electrolyte layer, and a lithium-indium alloy sheet is attached to the other side of the first solid electrolyte layer. An all-solid-state battery is produced after rolling under a pressure of 300 MPa.
[0145] The first solid electrolyte in the first solid electrolyte layer reacts with the lithium sheet to form a second solid electrolyte layer. The Young's modulus of the second solid electrolyte layer is 120 GPa, and the second solid electrolyte layer includes LiF and Li2O.
[0146] Comparative Example 1
[0147] The difference between this comparative example and Example 1 lies in the different compositions of the solid electrolyte membranes. Specific details are as follows:
[0148] Preparation of positive electrode:
[0149] The positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811), positive electrode binder PTFE, positive electrode conductive agent super-P and solid electrolyte Li6PS 2.5 O₂ClF₂ was uniformly mixed in a mass ratio of 70:3:2:25 and placed in a high-shear mixer for fiberization to form a first mixture. This first mixture was then roller-pressed to form a positive electrode layer at a temperature of 60°C for 5 minutes. The positive electrode layer was then laminated with the positive electrode current collector aluminum foil to produce the positive electrode.
[0150] Negative electrode: lithium sheet.
[0151] Preparation of solid electrolyte membrane:
[0152] Li2O, LiF and binder PVDF are mixed evenly and rolled under a pressure of 400 MPa to obtain a solid electrolyte membrane.
[0153] The mass ratio of Li2O, LiF and binder PVDF is 60:29.5:1. The Young's modulus of the solid electrolyte membrane is 120 GPa, the thickness is 50 μm, and the ionic conductivity λ2 is 1.2*10 -6 S / cm.
[0154] Preparation of all-solid-state batteries:
[0155] A positive electrode is attached to one side of the solid electrolyte membrane, and a lithium sheet is attached to the other side of the solid electrolyte membrane. An all-solid-state battery is produced after rolling under a pressure of 200 MPa.
[0156] Comparative Example 2
[0157] The difference between this comparative example and Example 1 is that the first solid electrolyte layer and the second solid electrolyte layer are prepared separately, and then a composite solid electrolyte layer is prepared by rolling. The details are as follows:
[0158] Preparation of positive electrode:
[0159] The positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811), positive electrode binder PTFE, positive electrode conductive agent super-P and solid electrolyte Li6PS 2.5 O₂ClF₂ was uniformly mixed in a mass ratio of 70:3:2:25 and placed in a high-shear mixer for fiberization to form a first mixture. This first mixture was then roller-pressed to form a positive electrode layer at a temperature of 60°C for 5 minutes. The positive electrode layer was then laminated with the positive electrode current collector aluminum foil to produce the positive electrode.
[0160] Negative electrode: lithium sheet.
[0161] Preparation of composite solid electrolyte membrane:
[0162] Preparation of the first solid electrolyte layer: The first solid electrolyte Li6PS 2.5 O2ClF was roll-pressed at a pressure of 400 MPa to obtain the first solid electrolyte layer.
[0163] Among them, the Young's modulus of the first solid electrolyte layer is 30 GPa, the thickness is 40 μm, and the ionic conductivity λ1 is 4.86 mS / cm.
[0164] Preparation of the second solid electrolyte layer: Li2O, LiF and binder PVDF were mixed evenly and rolled under a pressure of 400 MPa to obtain a solid electrolyte membrane.
[0165] The mass ratio of Li2O, LiF and binder PVDF is 60:29.5:1. The Young's modulus of the second solid electrolyte layer is 120 GPa, the thickness is 10 μm, and the ionic conductivity λ2 is 1.2*10 -6 S / cm.
[0166] Preparation of all-solid-state batteries:
[0167] A positive electrode is attached to the side of the first solid electrolyte layer away from the second solid electrolyte layer, and a lithium sheet is attached to the side of the second solid electrolyte layer away from the first solid electrolyte layer. An all-solid-state battery is produced after rolling under a pressure of 200 MPa.
[0168] Comparative Example 3
[0169] The difference between this comparative example and Example 1 is that a third solid electrolyte layer is used instead of the first solid electrolyte layer. The details are as follows:
[0170] Preparation of positive electrode:
[0171] The positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811), positive electrode binder PTFE, positive electrode conductive agent super-P and solid electrolyte Li6PS 2.5 O₂ClF₂ was uniformly mixed in a mass ratio of 70:3:2:25 and placed in a high-shear mixer for fiberization to form a first mixture. This first mixture was then roller-pressed to form a positive electrode layer at a temperature of 60°C for 5 minutes. The positive electrode layer was then laminated with the positive electrode current collector aluminum foil to produce the positive electrode.
[0172] Negative electrode: lithium sheet.
[0173] Preparation of the third solid electrolyte layer: The third solid electrolyte Li2ZrCl6 was roll-pressed at a pressure of 400 MPa to obtain the third solid electrolyte layer.
[0174] Among them, the Young's modulus of the third solid electrolyte layer is 38 GPa, the thickness is 50 μm, and the ionic conductivity λ3 is 1.17 mS / cm.
[0175] Preparation of all-solid-state batteries:
[0176] A positive electrode is attached to one side of the third solid electrolyte layer and a lithium sheet is attached to the other side. An all-solid-state battery is produced after rolling under a pressure of 200 MPa.
[0177] Test Case
[0178] (1) Thickness test
[0179] According to GB / T 6672-2001 standard, a Millimar C1208 thin film thickness gauge (Millimar C1208, manufactured by Millimar GmbH, Germany) was used to measure the thickness of the first solid electrolyte layer in the examples and comparative examples.
[0180] (2) Young's modulus test
[0181] Young's modulus measurements were performed using a Bruker DimensionIcon system equipped with an RTESPA525 probe (Bruker). The probe was calibrated, and then a 5 μm × 5 μm area on the sample surface was selected and tested with a peak force of 146.5 nN. The test data were fitted using the DMT model to calculate the Young's modulus.
[0182] (3) Ionic conductivity test
[0183] At room temperature, the composite solid electrolyte membranes obtained in the embodiment and the comparative example were connected to an electrochemical workstation, respectively, and an initial impedance test was performed. The final ionic conductivity was calculated according to the formula σ = I / (AR); where σ is the conductivity in mS / cm, I is the average thickness of the solid electrolyte membrane in cm, and A is the area of the solid electrolyte membrane in cm. 2 ; R is the bulk impedance of the solid electrolyte membrane, in Ω. The results are shown in Table 1 below.
[0184] (4) Internal resistance test
[0185] The battery was connected to an electrochemical workstation and the internal resistance of the battery was measured by EIS. The results are shown in Table 1 below.
[0186] (5) Cycle retention rate test
[0187] At 25°C, the battery was charged at 0.1C to a cutoff voltage of 4.25V. The battery was then switched to constant voltage charging until the cutoff current reached 0.05C, allowed to rest for 0.5h, and then discharged at 0.1C to a cutoff voltage of 3.0V. The battery was allowed to rest for 0.5h before entering the next charge-discharge cycle. This cycle was repeated for a total of 500 charge-discharge cycles. Capacity retention = discharge capacity after 500 cycles / initial discharge capacity. The results are shown in Table 1 below.
[0188] (6) 2C capacity retention test
[0189] At 25°C, a fully charged battery was discharged at a current of 0.1C to a cutoff voltage of 3.0V. The measured capacity was C0. At 25°C, a fully charged battery was discharged at a current of 2C to a cutoff voltage of 3.0V. The measured capacity was C1. C1 / C0 is the 2C discharge capacity retention rate referred to below. The results are shown in Table 1 below.
[0190]
[0191] According to the above experimental data, by adopting the composite solid electrolyte membrane provided in this application, a second solid electrolyte layer is generated by an in-situ reaction on the surface of the first solid electrolyte layer facing the lithium-containing negative electrode. The first solid electrolyte reacts with lithium to form the second solid electrolyte, and the second solid electrolyte does not react with the lithium negative electrode. That is, the second solid electrolyte layer is generated by an in-situ reaction between the first solid electrolyte layer and the lithium-containing negative electrode, forming a chemically stable interface. The second solid electrolyte layer acts as a passivation layer to prevent further reaction between the negative electrode and the first solid electrolyte, solving the problems of electrolyte decomposition and increased interfacial impedance caused by continuous side reactions when the traditional lithium metal negative electrode is in direct contact with the solid electrolyte.
[0192] Compared with the scheme in which the second solid electrolyte layer is directly used as the solid electrolyte membrane in Comparative Example 1, and compared with the scheme in which the first and second solid electrolyte layers are prepared separately and then roll-combined to obtain a composite solid electrolyte membrane in Comparative Example 2, there is no obvious interface between the first solid electrolyte layer and the second solid electrolyte layer in the composite solid electrolyte membrane of the present application, which improves the lithium ion transmission performance, reduces the internal resistance of the battery, and improves the cycle performance and capacity retention rate of the battery.
[0193] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0194] The above embodiments merely illustrate several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.
Claims
1. An all-solid-state battery, characterized in that: The invention comprises a positive electrode, a lithium-containing negative electrode and a composite solid electrolyte membrane disposed therebetween, wherein the composite solid electrolyte membrane comprises a first solid electrolyte layer and a second solid electrolyte layer, wherein the first solid electrolyte layer and the second solid electrolyte layer respectively comprise a first solid electrolyte and a second solid electrolyte; Wherein, the second solid electrolyte is generated by the reaction of the first solid electrolyte and the lithium-containing negative electrode; the second solid electrolyte does not react with the lithium-containing negative electrode; The lithium-containing negative electrode includes a lithium metal negative electrode or a lithium alloy negative electrode.
2. The all-solid-state battery according to claim 1, characterized in that The first solid electrolyte includes Li a1 P b1 S c1 O d1 Cl e1 F f1 , among which, a1+5b1=2c1+2d1+e1+f1, 4≤a1≤7, 0.8≤b1≤1.3, 2≤c1≤6, 0<d1≤3, 0<e1≤2, 0<f1≤2.
3. The all-solid-state battery according to claim 1, characterized in that The first solid electrolyte includes Li a2 P b2 S c2 O d2 Cl e2 , among which, a2+5b2=2c2+2d2+e2, 4≤a2≤7, 0.8≤b2≤1.3, 2≤c2≤6, 0<d2≤3, 0<e2≤4.
4. The all-solid-state battery according to claim 2 or 3, characterized in that: A Young's modulus of the first solid electrolyte layer is lower than a Young's modulus of the second solid electrolyte layer.
5. The all-solid-state battery according to claim 4, characterized in that The Young's modulus of the first solid electrolyte layer is 5 GPa to 40 GPa.
6. The all-solid-state battery according to claim 4, characterized in that The Young's modulus of the second solid electrolyte layer is 40 GPa to 200 GPa.
7. The all-solid-state battery according to claim 2 or 3, characterized in that: The second solid electrolyte layer includes Li2O and / or LiF.
8. The all-solid-state battery according to claim 2 or 3, characterized in that: The composite solid electrolyte membrane further includes a third solid electrolyte layer, which is disposed on a side of the first solid electrolyte layer close to the positive electrode, and has a Young's modulus of less than 50 GPa.
9. A method for preparing an all-solid-state battery according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. Roll-pressing the first solid electrolyte to obtain a first solid electrolyte layer; S2. Laying a lithium-containing negative electrode on one side of the first solid electrolyte layer and a positive electrode on the other side of the first solid electrolyte layer, or laminating a third solid electrolyte layer and a positive electrode on the other side of the first solid electrolyte layer, and then rolling the layer to produce an all-solid-state battery; The first solid electrolyte in the first solid electrolyte layer reacts with the lithium-containing negative electrode to generate a second solid electrolyte for constituting the second solid electrolyte layer.
10. The preparation method according to claim 9, characterized in that In step S2, the pressure of the roller pressing process is 100 MPa to 500 MPa.