Pre-lithiated alloy negative electrode for sulfide-based all-solid-state lithium battery and preparation method thereof
By employing a pre-lithiated alloy anode with an M metal matrix and a LiF/LiM interface layer in a sulfide-based all-solid-state lithium battery, the chemical reaction problem between the sulfide electrolyte and the lithium anode material was solved, achieving efficient lithium-ion distribution and improved battery performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- BEIJING INST OF TECH
- Filing Date
- 2023-09-28
- Publication Date
- 2026-07-14
AI Technical Summary
Sulfide electrolytes spontaneously react with lithium anode materials upon contact, which easily leads to pores and dendrite growth during charging and discharging. Existing preparation methods are demanding, costly, and unsuitable for large-scale production.
The pre-lithiation alloy anode employing an M metal substrate layer and a LiF/LiM dual-phase interface layer structure is prepared by adding a lithium salt solution containing CF bonds after the M metal thin film comes into contact with a lithium sheet, allowing it to stand, and applying pressure to form the LiF/LiM interface layer. The preparation method is simple and easy to promote.
It suppresses dendrite growth, improves the first-cycle coulombic efficiency, ensures high battery capacity, achieves uniform lithium-ion distribution, reduces interface impedance, and enhances battery performance.
Smart Images
Figure CN117038859B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a pre-lithiation alloy anode for sulfide-based all-solid-state lithium batteries and its preparation method, belonging to the field of new energy materials technology. Background Technology
[0002] Lithium-ion batteries have already had a significant impact on electronics, transportation, energy storage, and other fields. With the changing energy demands of society, there is a growing expectation for the development of batteries with higher energy density and greater safety. Next-generation all-solid-state battery technology is highly anticipated, as its development carries the mission of reshaping the global energy landscape, thus attracting widespread attention from industry and the industrial sector. Solid-state electrolytes, as one of its core components, have been developed in systems including oxides, sulfides, polymers, and halides.
[0003] Sulfide electrolytes have become a key research focus in all-solid-state battery development due to their high ionic conductivity and good mechanical properties. However, the spontaneous chemical reaction between sulfides and high-energy-density lithium anode materials, coupled with defects such as pores and interfacial dendrite growth during charge-discharge, hinders the realization of high-energy-density all-solid-state batteries. While alloying lithium powder with other metal powders can mitigate these issues, the development environment is demanding, prone to explosion, and lithium powder preparation and storage are difficult, hindering large-scale production. Another common strategy involves constructing a protective layer on the lithium metal surface using sputtering and chemical deposition methods, but this requires high selectivity for the protective layer, has poor operability, and is costly, also unsuitable for mass production. Therefore, developing an interface-stable, dendrite-free, and low-interfacial-resistance anode material is crucial for the application of sulfide electrolytes and helps to leverage the high-performance advantages of all-solid-state batteries. Summary of the Invention
[0004] In view of this, the purpose of the present invention is to provide a pre-lithiation alloy anode for sulfide-based all-solid-state lithium batteries and a method for preparing the same.
[0005] To achieve the above objectives, the technical solution of the present invention is as follows.
[0006] A pre-lithiation alloy anode for a sulfide-based all-solid-state lithium battery, the anode comprising an M metal matrix layer and a LiF / LiM dual-phase interface layer, wherein M is one or more of In, Al, Ag, Mg and Sn; the thickness of the LiF / LiM dual-phase interface layer is 10~100 micrometers, and the thickness of the LiF / LiM dual-phase interface layer < the thickness of the M metal matrix layer is ≤200 micrometers; based on the total mass of LiF and LiM as 100%, the mass fraction of LiF is 20%~70%, and the mass fraction of LiM is 30%~80%.
[0007] Preferably, the thickness of the LiF / LiM biphase interface layer is 20~50 micrometers.
[0008] Preferably, the thickness of the M substrate layer is 30~100 micrometers.
[0009] Preferably, based on the total mass of LiF and LiM as 100%, the mass fraction of LiF is 40%~60% and the mass fraction of LiM is 40%~60%.
[0010] The present invention discloses a method for preparing a pre-lithiated alloy anode for a sulfide-based all-solid-state lithium battery, the method comprising the following steps:
[0011] In an environment with humidity less than or equal to 5%, a high-purity M metal sheet is bonded to a lithium sheet, and a lithium salt solution containing CF bonds is added between the two to completely wet the contact surface. A pressure of 15~50 MPa is applied, and the contact time is left to stand for 12~36 hours. After standing, the metal sheet is peeled off from the lithium sheet, and the liquid on the surface of the metal sheet is dried and evaporated to obtain a sulfide-based pre-lithiated alloy anode for all-solid-state lithium batteries.
[0012] The concentration of the lithium salt solution containing CF bonds is 1~3 mol / L.
[0013] Preferably, the thickness of the high-purity M metal thin film is 30~1000 micrometers, and the purity is ≥99.9%.
[0014] Preferably, the lithium salt containing the CF bond is lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) or lithium bis(fluorosulfonyl)imide (LiFSI).
[0015] Preferably, the solvent of the lithium salt solution containing CF bonds is a carbonate compound, succinate, or pyrrolidine ionic liquid.
[0016] Preferably, during drying, the product is first dried in a glove box for 5 to 15 hours, and then transferred to a vacuum drying oven at 50 to 100°C for 6 to 12 hours.
[0017] A sulfide-based all-solid-state lithium battery, wherein the negative electrode of the battery is a pre-lithiation alloy negative electrode for a sulfide-based all-solid-state lithium battery according to the present invention, and the electrolyte is a sulfide-based solid electrolyte.
[0018] Beneficial effects
[0019] This invention provides a pre-lithiation alloy anode for sulfide-based all-solid-state lithium batteries, which generates an in-situ LiF / LiM biphase interface layer after pre-lithiation treatment on a thin metal surface. (1) The LiF phase hinders electrons from entering the sulfide electrolyte, reducing the reduction and decomposition of electrolyte components; (2) The LiM alloy phase improves lithium-ion deposition / stripping characteristics, resulting in a low surface energy and high Li-ion content of the alloy. + The diffusion rate helps the interface lithium ion flow and charge distribution to be uniform, thereby suppressing dendrite growth; (3) The excess lithium source in the alloy phase compensates for the limited active lithium ions of the cathode material, improves the first-cycle coulombic efficiency, and ensures the high capacity advantage of the battery; (4) The metal matrix can serve as a storage repository for active lithium, enabling larger capacity lithium insertion and extraction, and preventing excessive lithium deposition at the interface from forming dendrites.
[0020] This invention provides a pre-lithiation alloy anode for sulfide-based all-solid-state lithium batteries. The thickness of each layer needs to be controlled within a reasonable range. If the layer structure is too thin, it is not conducive to isolating electrons, causing the electrolyte to be reduced on the anode side to form a thick interface film, which is also not conducive to suppressing dendrite growth. If the layer structure is too thick, it is not conducive to reducing the lithium-ion transport rate and increasing the interface impedance.
[0021] This invention provides a method for preparing a pre-lithiated alloy anode for sulfide-based all-solid-state lithium batteries. The method involves adding a lithium salt solution containing CF bonds to the contact surface between an M metal thin film and a lithium sheet, allowing it to stand under high pressure for a period of time, and then pre-lithiating it to obtain the anode. The method is simple to operate and easy to promote. Attached Figure Description
[0022] Figure 1 This is a scanning electron microscope (SEM) image of the indium thin section described in Example 1.
[0023] Figure 2 This is a SEM image of the cross-section of the alloy negative electrode described in Example 1.
[0024] Figure 3 The image shows the Li 1s spectrum of the alloy negative electrode described in Example 1.
[0025] Figure 4 The cycling performance curve of the symmetrical battery assembled as described in Example 1.
[0026] Figure 5 The cycling performance curve of the half-cell assembled as described in Example 1.
[0027] Figure 6 This is a SEM image of the cross-section of the alloy negative electrode described in Comparative Example 2.
[0028] Figure 7 The cycle performance curves of the symmetrical battery assembled with the alloy negative electrode described in Comparative Example 2 are shown.
[0029] Figure 8 The cycling performance curves of the half-cell assembled as described in Example 2 and Comparative Example 2 are shown. Detailed Implementation
[0030] The present invention will be further described in detail below with reference to specific embodiments.
[0031] The following are examples and comparative examples:
[0032] (1) SEM test: The microstructure of the composite electrode was analyzed using Hitachi's S-3500N scanning electron microscope.
[0033] (2) XPS test, using Thermo Fisher Scientific X-ray photoelectron spectrometer.
[0034] (3) Symmetrical battery assembly: 80 mg of sulfide electrolyte is loaded into a 13 mm battery mold, 70 MPa pressure is applied, and the prepared negative electrode material is placed on both sides of the electrolyte to assemble a symmetrical battery.
[0035] (4) Button battery assembly: 80 mg of sulfide electrolyte is loaded into a 13 mm battery mold and a pressure of 70 MPa is applied. The composite positive electrode material (sulfide electrolyte: oxide positive electrode material = 7:3) is added to one side of the electrolyte and a pressure of 250 MPa is applied. The prepared negative electrode material is placed on the other side of the electrolyte to assemble an all-solid-state battery. The battery is charged and discharged at a pressure of 50 MPa.
[0036] (5) Electrochemical performance test: Charge-discharge cycle test was conducted using the LAND battery test system (CT2001A) of Wuhan Jinno Electronics Co., Ltd.
[0037] Example 1
[0038] (1) In an environment with humidity below 5%, high-purity indium sheets (In purity ≥ 99.9%) are repeatedly rolled into metallic indium sheets by a roller press, with a thickness of 83.6 micrometers;
[0039] (2) Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) was added to 1-methyl-1-propylpyrrolidine bis(trifluoromethanesulfonyl)imide salt to prepare a solution with a molar concentration of 2 mol / L;
[0040] (3) The indium sheet is brought into contact with the lithium sheet, and the solution is added in between to completely wet the sheet. A pressure of 20 MPa is applied, and the contact time is 24 hours.
[0041] (4) The indium sheet is peeled off from the lithium sheet, dried in a glove box for 5 hours, and then transferred to a vacuum drying oven at 60°C for 10 hours to obtain a sulfide-based pre-lithiation alloy anode for all-solid-state lithium batteries.
[0042] The cross-section of the indium thin film and pre-lithiation alloy anode is as follows: Figure 1-2 As shown, the results indicate that the thickness of the alloy anode is 96 micrometers, and there is a boundary line between the interface layer and the indium substrate, with the interface layer thickness being 36 micrometers and the indium substrate thickness being 60 micrometers.
[0043] The XPS test results of the alloy negative electrode are as follows: Figure 3 As shown, the results indicate that the surface of the alloy anode consists of two phases, LiF and LiIn. Based on the peak area integral, the LiF content in the interface layer is approximately 49.7%, and the LiIn content is 50.3%.
[0044] The alloy anode was assembled into a symmetrical battery, and the symmetrical battery underwent lithium deposition and stripping tests, such as... Figure 4 As shown, the alloy anode exhibits excellent electrochemical stability, with a current density of 0.64 mA cm⁻¹ at room temperature. -2 Stable cycle for 1000 hours.
[0045] The alloy negative electrode was matched with a lithium cobalt oxide positive electrode to assemble a coin cell, and the coin cell was subjected to charge-discharge tests, such as... Figure 5 As shown, the discharge specific capacity during the first cycle is 129 mAh g at an operating voltage of 2.7~4.2 V. -1 The discharge specific capacity after 100 cycles is 121.9 mAh g. -1 The capacity retention rate reached 94.42%.
[0046] Example 2
[0047] (1) In an environment with humidity below 5%, high-purity silver sheets (Ag purity ≥ 99.9%) are repeatedly rolled into silver sheets by a roller press, with a thickness of 30 micrometers;
[0048] (2) Add lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) to succinate to prepare a solution with a molar concentration of 1 mol / L;
[0049] (3) The silver foil is brought into contact with the lithium sheet, the solution is added in the middle for wetting, a pressure of 30 MPa is applied, and the contact time is 24 hours.
[0050] (4) The silver foil is peeled off from the lithium sheet, dried in a glove box for 5 hours, and then transferred to a vacuum drying oven at 60°C for 10 hours to obtain a pre-lithiated alloy anode.
[0051] The cross-sectional test results of the silver thin and pre-lithiated alloy anodes show that the thickness of the alloy anode is 53 micrometers, and there is a boundary line between the interface layer and the lithium substrate. The interface layer thickness is 20 micrometers, and the silver substrate thickness is 33 micrometers.
[0052] XPS test results of the lithium metal electrode show that the electrode surface is composed of two phases, LiF and LiAg. According to the peak area integral, the LiF content of the interface layer is about 55.3% and the LiAg content is 44.7%.
[0053] The alloy anode was assembled into a symmetrical cell, and lithium deposition and stripping tests were performed on the symmetrical cell. The anode exhibited excellent electrochemical stability, with a current density of 0.64 mA cm⁻¹ at room temperature. -2 Stable cycle for 800 hours.
[0054] The alloy negative electrode was matched with a lithium cobalt oxide positive electrode to assemble a coin cell, and the coin cell was subjected to charge-discharge tests, such as... Figure 8 As shown, the discharge specific capacity during the first cycle is 123 mAh g at an operating voltage of 2.7~4.2 V. -1 The discharge specific capacity after 100 cycles is 117.6 mAh g. -1 The capacity retention rate reached 95.6%.
[0055] Example 3
[0056] (1) In an environment with humidity below 5%, high-purity aluminum sheets are repeatedly rolled into metal sheets by a roller press, with a thickness of 200 micrometers;
[0057] (2) Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) was added to 1-methyl-1-propylpyrrolidine bis(trifluoromethanesulfonyl)imide salt to prepare a solution with a molar concentration of 3 mol / L;
[0058] (3) The aluminum sheet is brought into contact with the lithium sheet, the solution is added in the middle for wetting, a pressure of 30 MPa is applied, and the contact time is 30 hours.
[0059] (4) Peel the aluminum sheet off the lithium sheet, dry it in a glove box for 5 hours, and then transfer it to a vacuum drying oven at 60°C for 10 hours to obtain a pre-lithiated alloy anode.
[0060] The cross-sectional test results of the aluminum thin film and the alloy negative electrode show that the thickness of the alloy negative electrode is 223 micrometers, and there is a boundary line between the interface layer and the aluminum substrate. The thickness of the interface layer is 30 micrometers, and the thickness of the aluminum substrate is 193 micrometers.
[0061] XPS test results of the alloy anode show that the surface of the anode is composed of two phases, LiF and LiAl. According to the peak area integral, the LiF content of the interface layer is about 59.3% and the LiAl content is 40.7%.
[0062] The alloy anode was assembled into a symmetrical cell, and lithium deposition and stripping tests were performed on the symmetrical cell. The alloy anode exhibited excellent electrochemical stability, with a current density of 0.64 mA cm⁻¹ at room temperature. -2 Stable cycle time 1200 hours.
[0063] The alloy negative electrode was matched with a lithium cobalt oxide positive electrode to assemble a coin cell. Charge-discharge tests were performed on the coin cell, and the discharge specific capacity during the first cycle was 126 mAh g⁻¹ under a working voltage of 2.7–4.2 V. -1 The discharge specific capacity after 100 cycles is 118.2 mAh g. -1 The capacity retention rate reached 93.8%.
[0064] Comparative Example 1
[0065] (1) In an environment with humidity below 5%, high-purity indium metal (lithium purity ≥ 99.9%) is repeatedly rolled into indium thin film by a roller press, with a thickness of 150 micrometers;
[0066] (2) Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) was added to 1-methyl-1-propylpyrrolidine bis(trifluoromethanesulfonyl)imide salt to prepare solution A with a molar concentration of 10 mol / L;
[0067] (3) Indium sheet (purity ≥ 99.9%) is brought into contact with lithium sheet, solution A is added in the middle to completely wet it, pressure of 20 MPa is applied, and the contact time is 72 hours.
[0068] (4) The indium sheet is peeled off from the lithium sheet, dried in a glove box for 5 hours, and then transferred to a vacuum drying oven at 60°C for 10 hours to obtain an alloy negative electrode.
[0069] The cross-sectional test results of the indium thin and alloy anode show that the thickness of the pre-lithiated alloy anode is 183.2 micrometers, and there is a boundary line between the interface layer and the indium substrate. The interface layer thickness is 62 micrometers, and the indium substrate thickness is 121.2 micrometers.
[0070] XPS test results of the electrode show that the surface of the alloy negative electrode is composed of two phases, LiF and LiIn. According to the peak area integral, the LiF content of the interface layer is about 92.7% and the LiIn content is 7.3%.
[0071] The alloy anode was assembled into a symmetrical cell, and lithium deposition and stripping tests were performed on the symmetrical cell. The alloy anode exhibited poor electrochemical stability, with a current density of 0.64 mA cm⁻¹ at room temperature. -2 Short-circuit behavior occurs during looping.
[0072] The alloy negative electrode was matched with a lithium cobalt oxide positive electrode to assemble a coin cell. Charge-discharge tests were performed on the coin cell, and the discharge specific capacity during the first cycle was 55.6 mAh g⁻¹ under a working voltage of 2.7–4.2 V. -1 The discharge specific capacity after 100 cycles is 36.5 mAh g. -1 The capacity retention rate reached 65.58%.
[0073] Comparative Example 2
[0074] (1) In an environment with humidity below 5%, high-purity indium metal (lithium purity ≥ 99.9%) is repeatedly rolled into lithium film by a roller press, and the thickness of the indium film is 82 micrometers;
[0075] (2) Indium film (purity ≥ 99.9%) is brought into contact with lithium sheet, a pressure of 20 MPa is applied, and the contact time is 12 hours;
[0076] (4) The indium sheet is peeled off from the lithium sheet, dried in a glove box for 5 hours, and then transferred to a vacuum drying oven at 60°C for 10 hours to obtain an alloy negative electrode.
[0077] The cross-section of the alloy negative electrode is as follows: Figure 6 As shown, the results indicate that the thickness of the pre-lithiated alloy anode is 84 micrometers, and there is no boundary between the interface layer and the indium substrate, making it impossible to distinguish the interface layer.
[0078] XPS test results of the alloy anode show that no LiF-containing peaks were formed on the surface of the alloy anode, only peaks of indium and trace alloys were formed.
[0079] The negative electrode is assembled into a symmetrical battery, and the symmetrical battery undergoes lithium deposition and stripping tests, such as... Figure 7 As shown, the negative electrode material exhibits poor electrochemical stability, with a current density of 0.64 mA cm⁻¹ at room temperature. -2 Short-circuit behavior occurs during looping.
[0080] The negative electrode material was matched with a lithium cobalt oxide positive electrode to assemble a coin cell, and the coin cell was subjected to charge-discharge tests, such as... Figure 8 As shown, the discharge specific capacity during the first cycle is 79.2 mAh g at an operating voltage of 2.7–4.2 V. -1 The discharge specific capacity after 100 cycles is 10.2 mAh g. -1 The capacity retention rate reached 12.9%.
[0081] Comparative Example 3
[0082] (1) In an environment with humidity below 5%, high-purity aluminum metal (lithium purity ≥ 99.9%) is repeatedly rolled into aluminum sheets by a roller press, with a thickness of 100 micrometers;
[0083] (2) Add lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) to succinate to prepare a solution with a molar concentration of 3 mol / L;
[0084] (3) Add the solution to the aluminum sheet, apply a pressure of 20 MPa, and allow it to stand for 12 hours.
[0085] (4) Take out the aluminum foil, dry the evaporated liquid on the surface, and obtain a negative electrode material.
[0086] The cross-sectional results of the negative electrode show that the aluminum thin negative electrode is 102 micrometers in diameter, and there is no boundary between the interface layer and the aluminum substrate, making it impossible to distinguish the interface layer.
[0087] XPS test results of the negative electrode show that only lithium fluoride exists on the surface of the negative electrode.
[0088] The negative electrode was assembled into a symmetrical cell, and lithium deposition and stripping tests were performed on the symmetrical cell. The negative electrode material exhibited poor electrochemical stability, with a current density of 0.64 mA cm⁻¹ at room temperature. -2 Short-circuit behavior occurs during looping.
[0089] The negative electrode material was matched with a lithium cobalt oxide positive electrode to assemble a coin cell. Charge-discharge tests were performed on the coin cell, and the discharge specific capacity during the first cycle was 112 mAh g⁻¹ under a working voltage of 2.7–4.2 V. -1 The discharge specific capacity after 100 cycles is 45.2 mAh g. -1 The capacity retention rate reached 40.3%.
[0090] In summary, the invention includes, but is not limited to, the above embodiments. Any equivalent substitutions or partial improvements made under the spirit and principles of this invention shall be considered to be within the protection scope of this invention.
Claims
1. A pre-lithiation alloy anode for a sulfide-based all-solid-state lithium battery, characterized in that: The negative electrode is composed of a lithium substrate layer and a LiF / LiM dual-phase interface layer, where M is one or more of In, Al, Ag, Mg and Sn; the thickness of the LiF / LiM dual-phase interface layer is 10~100 micrometers, and the thickness of the LiF / LiM dual-phase interface layer < the thickness of the lithium substrate layer is ≤200 micrometers. Based on the total mass of LiF and LiM as 100%, the mass fraction of LiF is 20%~70%, and the mass fraction of LiM is 30%~80%.
2. The pre-lithiation alloy anode for a sulfide-based all-solid-state lithium battery as described in claim 1, characterized in that: The thickness of the LiF / LiM biphase interface layer is 20~50 micrometers.
3. The pre-lithiation alloy negative electrode for a sulfide-based all-solid-state lithium battery as described in claim 1, characterized in that: The thickness of the lithium substrate layer is 30~100 micrometers.
4. The pre-lithiation alloy anode for a sulfide-based all-solid-state lithium battery as described in claim 1, characterized in that: With the total mass of LiF and LiM as 100%, the mass fraction of LiF is 40%~60%, and the mass fraction of LiM is 40%~60%.
5. A method for preparing a pre-lithiation alloy anode for a sulfide-based all-solid-state lithium battery as described in any one of claims 1 to 4, characterized in that: The method steps include: In an environment with humidity less than or equal to 5%, a high-purity M metal sheet is bonded to a lithium sheet, and a lithium salt solution containing CF bonds is added between the two to completely wet the contact surface. A pressure of 15~50 MPa is applied, and the contact time is left to stand for 12~36 hours. The metal sheet is then peeled off from the lithium sheet, and the liquid on the surface of the metal sheet is dried and evaporated to obtain a sulfide-based pre-lithiated alloy anode for all-solid-state lithium batteries. The concentration of the lithium salt solution containing CF bonds is 1~3 mol / L.
6. The method for preparing a pre-lithiation alloy anode for a sulfide-based all-solid-state lithium battery as described in claim 5, characterized in that: The purity of the high-purity M metal is ≥99.9%; the thickness of the lithium sheet is 30 micrometers to 1 millimeter, and the purity is ≥99.9%.
7. The method for preparing a pre-lithiation alloy anode for a sulfide-based all-solid-state lithium battery as described in claim 5, characterized in that: The lithium salt containing CF bonds is lithium bis(trifluoromethanesulfonyl)imide or lithium bis(fluorosulfonyl)imide.
8. The method for preparing a pre-lithiation alloy anode for a sulfide-based all-solid-state lithium battery as described in claim 7, characterized in that: The solvent for the lithium salt solution containing CF bonds is a carbonate compound, succinate, or pyrrolidine ionic liquid.
9. The method for preparing a pre-lithiation alloy anode for a sulfide-based all-solid-state lithium battery as described in claim 5, characterized in that: During drying, first dry in a glove box for 5 to 15 hours, then transfer to a vacuum drying oven at 50 to 100°C for 6 to 12 hours.
10. A sulfide-based all-solid-state lithium battery, characterized in that: The negative electrode of the battery is a pre-lithiation alloy negative electrode for a sulfide-based all-solid-state lithium battery as described in any one of claims 1 to 4, and the electrolyte is a sulfide-based solid electrolyte.