Method for producing porous material of porous lithium and its alloy and application thereof
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANGHAI JIAOTONG UNIV
- Filing Date
- 2023-03-31
- Publication Date
- 2026-06-16
Smart Images
Figure CN116344783B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a technology in the field of lithium battery manufacturing, specifically a method for preparing porous lithium and its alloys into porous materials and their applications. Background Technology
[0002] Lithium-ion batteries are widely used in various fields, including portable electronic devices and power batteries. However, due to the limited energy density of graphite anodes, they cannot meet the requirements for high energy density, necessitating the development of new high-energy-density anode materials.
[0003] Lithium metal is valued for its extremely low electrode potential (-3.04V) and high theoretical specific capacity (3860mAh g / g). -1 Lithium metal anodes are ideal choices for high-energy-density rechargeable batteries. However, they suffer from severe volume expansion and dendrite growth during cycling, leading to battery performance degradation and even safety issues. Currently, much research focuses on modifying electrolytes, constructing artificial SEIs, and building three-dimensional metal anodes using three-dimensional framework materials. Among these, constructing three-dimensional porous metal electrodes is an effective strategy. Summary of the Invention
[0004] This invention addresses the shortcomings of existing porous composite electrodes, which have low energy density and porosity. It proposes a method for preparing porous lithium and its alloys, and their applications. This method significantly suppresses the volume expansion of the negative electrode during cycling, reduces the nucleation overpotential of lithium metal, and induces uniform lithium deposition. Simultaneously, the substances produced during the decomposition of the foaming agent react with the lithium metal, forming a protective layer around the pore walls. This greatly suppresses side reactions between the electrode and the electrolyte, accelerates lithium-ion transport, and, through its self-supporting structure, eliminates the need for an additional porous framework, avoiding electrode energy density loss and reducing manufacturing costs. This achieves uniform and dense lithium deposition, suppresses volume expansion and dendrite growth of the lithium negative electrode, and improves the electrochemical performance of lithium metal batteries.
[0005] This invention is achieved through the following technical solution:
[0006] This invention relates to a method for preparing porous materials of porous lithium and its alloys. First, a foaming agent is thoroughly mixed with metallic lithium or lithium alloy. Then, the mixed lithium metal or lithium alloy is heated to a molten state by orderly heating. The foaming agent decomposes under heat and releases gas to generate a three-dimensional porous structure in the melt. After the melt cools and solidifies, the porous material is obtained.
[0007] The thorough mixing refers to the process of uniformly mixing a foil obtained by rolling lithium metal or lithium alloy with a uniformly sized foaming agent obtained by ball milling or recrystallization through rolling.
[0008] The self-supporting porous structure refers to: open pores and / or closed pores, that is, cavities and channels in porous lithium and its alloy electrodes that are connected to the external electrolyte and / or cavities and channels that are not connected to the external surface and into which the electrolyte cannot penetrate.
[0009] The lithium alloy is LiM, wherein M is Na, K, Mg, Zn, Ca, Sn, Si, Ag, Au, Al, In, Bi or a combination thereof. Preferably, it is obtained by mixing metallic lithium with other metals, melting and heating it under an inert atmosphere and then cooling it to room temperature, or by mixing metallic lithium with other metals and then rolling it.
[0010] The foil material has a thickness of 10–500 μm.
[0011] The ball milling process yields a foaming agent with a particle diameter distribution of 100 nm to 30 μm, wherein the foaming agent is an organic foaming agent and / or an inorganic foaming agent.
[0012] The organic foaming agent mentioned herein is an N-nitroso compound, an azo compound (such as azodicarbonamide, dinitrosopeptimethylenetetramine, etc.), a sulfonyl hydrazine compound, a urea compound (such as urea, p-toluenesulfonamide, benzenesulfonamide, etc.), a chlorofluorocarbon, or a combination thereof.
[0013] The inorganic foaming agent mentioned herein is a combination of carbonates (sodium bicarbonate, potassium bicarbonate, magnesium bicarbonate, ammonium bicarbonate, sodium chloride, etc.), nitrites (such as a mixture of sodium nitrite and ammonium chloride), water glass, silicon carbide, carbon black, or combinations thereof.
[0014] The mass ratio of the foil to the foaming agent is 20:1 to 100:1.
[0015] The heating process specifically involves raising the temperature from room temperature at a rate of 1°C / min to 20°C / min, maintaining the temperature at 100°C to 800°C for 1 to 600 minutes, and finally allowing it to cool naturally back to room temperature.
[0016] This invention relates to a method for preparing a lithium battery electrode based on the above-mentioned porous material, wherein a porous lithium battery electrode supported by an alloy skeleton is obtained by immersing a porous lithium electrode in a metal halide solution for alloying interface layer modification.
[0017] The metal halide solution refers to: NaCl, KCl, MgCl2, ZnCl2, CaCl2, SnCl4, SiCl4, AgCl, AuCl, AlCl3, InCl3, BiCl3, or a combination thereof.
[0018] This invention relates to lithium battery electrodes prepared by the above method, which, from the outside to the inside, include: a lithium and lithium alloy phase, a self-supporting porous structure of the lithium and lithium alloy electrode, and an interface modification layer on the electrode surface and inside the bulk phase. The lithium alloy phase serves as a lithiophilic site during the lithium deposition process, the porous structure of the lithium and lithium alloy electrode provides a space for the deposited metallic lithium, and the interface modification layer on the electrode surface and inside the bulk phase provides interface protection and a fast ion migration interface for the electrode.
[0019] The interface modification layer is an inorganic and / or organic material containing lithium, specifically: LiM, where M is Na, K, Mg, Zn, Ca, Sn, Si, Ag, Au, Al, In, Bi or a combination thereof; or a product obtained by reacting lithium or lithium alloy with a foaming agent at high temperature, such as Li3N, LiF, Li2O, Li2CO3 or a combination thereof.
[0020] This invention relates to the application of the aforementioned lithium battery electrode, using it as a negative electrode material, matched with the positive electrode and electrolyte, to assemble a high-energy-density lithium metal battery.
[0021] The positive electrode includes an embedded positive electrode battery, a conversion positive electrode, and an embedded / conversion composite positive electrode. Attached Figure Description
[0022] Figure 1 This is a cross-sectional schematic diagram of a three-dimensional porous lithium electrode or lithium alloy electrode.
[0023] Figure 2 The image shows a surface SEM image of the porous lithium-magnesium alloy electrode prepared in Example 1.
[0024] Figure 3 This is a comparison chart of the specific capacity of the porous lithium metal electrode obtained during the preparation process of Example 6 and a commercial lithium electrode;
[0025] Figure 4 The electrolyte permeability test of the porous lithium-magnesium alloy electrode prepared in Example 1 demonstrates that the electrode has an open pore structure that communicates with the outside world.
[0026] Figure 5 The symmetrical cells in Example 1, Comparative Example 1, and Comparative Example 2 were tested at 3 mA / cm. -2 -3mAhcm -2 A comparison of voltage-time curves under cyclic conditions;
[0027] Figure 6 The symmetrical cells in Example 1, Comparative Example 1, and Comparative Example 2 were tested at 1 mA / cm. -2 -1mAhcm -2 A comparison of voltage-time curves under cyclic conditions;
[0028] Figure 7 The symmetrical cells in Example 1 and Comparative Example 2 were tested at 5 mA / cm. -2 -1mAhcm -2 Comparison of electrode volume changes after 100 cycles under certain conditions. Detailed Implementation
[0029] Example 1
[0030] This embodiment relates to the preparation of a self-supporting porous lithium and lithium alloy anode and its application in lithium metal batteries. The specific preparation process includes the following steps:
[0031] Step 1) Place 1g of azodicarbonamide, 5ml of water, and 10μl of sodium dodecyl sulfate aqueous solution with a concentration of 0.001g / ml into a planetary ball mill for ball milling. The ball milling conditions are set as follows: 500r / min, 5min operation, 5min stop, alternating, for a total working time of 16h;
[0032] Step 2) The slurry obtained after ball milling is dried in a vacuum oven at 100°C for 12 hours;
[0033] Step 3) Disperse 15 mg of dried azodicarbonamide powder in 5 ml of DME solution and sonicate in an ultrasonic cleaner for 2 h until a uniformly dispersed azodicarbonamide dispersion is obtained.
[0034] Step 4) Weigh lithium and magnesium sheets in advance with a mass ratio of 21:8 (atomic ratio of 9:1). First, place the lithium sheets in a muffle furnace and heat to 300°C. After the lithium sheets are heated to melt, mix them with the weighed magnesium sheets. When both are in a molten state, stir with a stainless steel rod to mix them evenly. Then, keep the mixture at 300°C for 2 hours and let it cool naturally to room temperature to obtain a lithium-magnesium alloy with the composition Li9Mg.
[0035] Step 5) Roll press 500mg of the lithium-magnesium alloy prepared in step 4 into a 100μm sheet. Then, apply the azodicarbonamide dispersion obtained in step 3 evenly to the surface of the alloy material in multiple batches. After the solvent has completely evaporated, fold the alloy sheet and roll it repeatedly to 100μm so that the azodicarbonamide is evenly dispersed in the alloy material.
[0036] Step 6) The alloy foil obtained by rolling is punched into a circular sheet with a diameter of 12mm and placed in a muffle furnace for heat treatment. The specific heating process of the muffle furnace includes: heating to 200℃ at 25℃ for 60min, holding for 20min, then heating to 260℃ for 7min, holding for 20min, and then naturally cooling to room temperature; after the heat treatment is completed, an alloy negative electrode with a porous structure is obtained.
[0037] Step 7) The electrode prepared in Step 6 was applied to a lithium metal battery for electrochemical testing. A symmetrical battery was assembled using porous alloy electrodes, a 0.2M LiPF6, 0.2M LiBF4, 0.8M LiDFOBinDEC:FEC = 2:1 vol% electrolyte, and a Celgard 2400 separator. The battery was tested at 1 mA / cm². -2 -1mAhcm -2 3mAcm -2 -1mAhcm -2 3mAcm -2 -3mAhcm -2 Long-cycle testing was performed under these conditions; and the results were tested at 1 mA cm⁻¹. -2 -1mAhcm -2 The electrode was characterized by SEM after 200 cycles under the specified conditions to observe the deposition morphology of lithium metal and the change in electrode thickness. The on-surface capacity was 4 mAh / cm². -2 The NCM811 cathode was paired with a 0.2M LiPF6, 0.2M LiBF4, and 0.8M LiDFOBinDEC:FEC = 2:1 Vol% electrolyte to assemble a full cell, which was then subjected to long-cycle testing at 0.5C, 1C, and 2C rates.
[0038] In the above steps, except for steps 1-3, all other steps are carried out in a glove box where the water content and oxygen content are both below 0.1 ppm.
[0039] Example 2
[0040] The difference between this implementation and Example 1 is as follows:
[0041] Weigh 400 mg of lithium metal foil and 200 mg of indium metal foil, and then prepare a sheet with a thickness of 100 μm by rolling. Then, the azodicarbonamide dispersion obtained in step 1 is coated on the surface of the sheet multiple times. After the solvent has completely evaporated, the sheet is repeatedly folded and rolled until the azodicarbonamide is evenly dispersed in the sheet formed by the mixture of lithium metal and indium metal.
[0042] The obtained thin sheet was punched into an electrode with a diameter of 12 mm, and then placed in a muffle furnace for heat treatment. The heating process specifically included: heating from 25°C to 200°C for 60 min, holding at that temperature for 20 min, then heating to 240°C for 7 min, holding at that temperature for 20 min, and then naturally cooling to room temperature. After the heat treatment was completed, a electrode with Li and Li₂ was obtained. 13 In3 porous lithium indium alloy.
[0043] Example 3
[0044] The difference between this implementation and Example 1 is as follows:
[0045] 420 mg of metallic lithium was weighed and placed in a muffle furnace and heated to a molten state at 300 °C. Then, 324 mg of metallic silver powder was added to the molten lithium. The mixture was continuously stirred with a stainless steel rod to accelerate the dissolution of the silver. Finally, the mixture was cooled to room temperature to obtain Li. 20 Ag lithium-silver alloy;
[0046] The lithium silver alloy prepared by 500mg was rolled into a 100μm sheet. Then, the azodicarbonamide dispersion was evenly coated on the surface of the alloy material in multiple batches. After the solvent evaporated completely, the alloy sheet was folded and repeatedly rolled to 100μm to make the azodicarbonamide evenly dispersed in the alloy material.
[0047] Step 4) The alloy sheet obtained by rolling is punched into a circular sheet with a diameter of 12mm and placed in a muffle furnace for heat treatment. The specific heating process of the muffle furnace includes: heating from 25℃ to 200℃ for 60 minutes, holding for 20 minutes, then heating to 270℃ for 7 minutes, holding for 20 minutes, and then naturally cooling to room temperature. After the heat treatment is completed, an alloy negative electrode with a porous structure is obtained.
[0048] Example 4
[0049] The difference between this implementation and Example 1 is as follows:
[0050] 420 mg of metallic lithium was weighed and placed in a muffle furnace and heated to a molten state at 300 °C. Then, 195 mg of metallic zinc was added to the molten lithium, and the zinc was continuously stirred with a stainless steel rod to accelerate its dissolution. Finally, the mixture was cooled to room temperature to obtain Li. 20 Lithium-zinc alloys of Zn;
[0051] The lithium-zinc alloy prepared by 500mg was rolled into a 100μm sheet. Then, the azodicarbonamide dispersion was evenly coated on the surface of the alloy material in multiple batches. After the solvent evaporated completely, the alloy sheet was folded and repeatedly rolled to 100μm to make the azodicarbonamide evenly dispersed in the alloy material.
[0052] Example 5
[0053] The difference between this implementation and Example 1 is as follows:
[0054] Weigh 300 mg of metallic lithium and place it in a muffle furnace. Heat it to a molten state at 300 °C. Then add 300 mg of metallic calcium to the molten metallic lithium. Initially, the calcium floats on the liquid lithium. After holding the temperature for 1 minute, the metallic calcium can melt into the metallic lithium. Finally, cool it to room temperature to obtain a lithium-rich lithium-calcium alloy with the composition of Li and CaLi2.
[0055] 500mg of lithium-calcium alloy was rolled into a 100μm sheet. Then, azodicarbonamide dispersion was evenly applied to the surface of the alloy material in multiple applications. After the solvent had completely evaporated, the alloy sheet was folded and repeatedly rolled to 100μm to ensure that the azodicarbonamide was evenly dispersed in the alloy material.
[0056] Example 6
[0057] The difference between this implementation and Example 1 is as follows:
[0058] Weigh 500mg of metallic lithium foil and prepare it into a lithium foil with a thickness of 100μm by rolling. Then, apply the azodicarbonamide dispersion to the surface of the lithium foil in multiple applications. After the solvent has completely evaporated, repeatedly fold and roll the lithium foil until the azodicarbonamide is evenly dispersed in the lithium foil.
[0059] Lithium foil is punched into electrode sheets with a diameter of 12 mm and then placed in a muffle furnace for heating treatment. The heating process specifically includes: heating from 25°C to 200°C for 60 min, holding at that temperature for 20 min, then heating to 240°C for 7 min, holding at that temperature for 20 min, and then naturally cooling to room temperature. After the heating treatment is completed, a metal lithium sheet with a porous structure is obtained.
[0060] Example 7
[0061] The difference between this implementation and Example 6 is that:
[0062] Weigh 0.2271g InCl3 and dissolve it in 8.9g THF, then stir until homogeneous to obtain an indium chloride solution with a concentration of 0.167mol / L;
[0063] The porous lithium sheet obtained in Example 6 was immersed in the indium chloride solution prepared in step 2 for 20 seconds. After being taken out, the lithium sheet was cleaned with THF to obtain a porous alloy material with a conformal alloy modification layer.
[0064] Comparative Example 1
[0065] Comparative Example 1 relates to the preparation of an alloy electrode and its application in lithium metal batteries. The process includes the following steps:
[0066] Step 1) Weigh lithium and magnesium sheets in advance with a mass ratio of 21:8 (atomic ratio of 9:1). First, place the lithium sheets in a muffle furnace and heat to 300°C. After the lithium sheets are heated to melt, mix them with the weighed magnesium sheets. When both are in a molten state, stir with a stainless steel rod to mix them evenly. Then, keep the mixture at 300°C for 2 hours and let it cool naturally to room temperature to obtain a lithium-magnesium alloy with the composition Li9Mg.
[0067] Step 2) The lithium-magnesium alloy obtained in Step 1 is processed into a thin sheet with a thickness of 100μm by rolling, and then punched into an electrode sheet with a diameter of 12mm;
[0068] Step 3) is the same as step 7 in Example 1.
[0069] like Figure 2 As shown, at 3mAcm -2 -3mAhcm -2 Under the cycling conditions, the overpotential-time curve shows that the porous alloy anode prepared by Example 1 exhibits a smaller overpotential and better cycling stability under high current density and large area specific capacity conditions. This indicates that a more standardized lithium deposition behavior occurs on the surface of the electrode, which greatly suppresses the volume expansion of the electrode during cycling. At the same time, it has good interface stability, reduces the side reactions between the electrode and the electrolyte, obtains a more stable SEI, and reduces the generation of "dead lithium".
[0070] Similarly, from Figure 3 The same conclusion can be drawn from this.
[0071] Comparative Example 2
[0072] This comparative sample relates to the preparation of a lithium metal anode and its application in lithium metal batteries. The process includes the following steps:
[0073] Step 1) A lithium foil with a thickness of 500 μm is rolled into a metallic lithium foil with a thickness of 100 μm, and then punched into an electrode with a diameter of 12 mm.
[0074] Step 2) is the same as step 7 in Example 1.
[0075] like Figure 2 As shown, at 3mAcm -2 -3mAhcm -2 Under the cycling conditions, the overpotential of the comparative sample exhibited significant fluctuations over time, indicating that the pure lithium electrode exhibits substantial instability under high current density and large areal capacity cycling conditions. In contrast, the porous lithium-magnesium alloy anode prepared in Example 1 significantly improves the stability of the battery.
[0076] Similarly, from Figure 3 The same conclusion can be drawn from this.
[0077] Compared with the prior art, the present invention does not require the introduction of additional inactive substrate framework materials for the three-dimensional porous structure design of metal electrodes, thus avoiding the reduction of electrode energy density caused by inactive materials. By utilizing the gas generation principle of thermal decomposition foaming agent, porous alloy materials supported by alloy framework are prepared by melting method on the one hand, and porous alloy materials with conformal alloy modification layer are prepared by in-situ alloying reaction of lithium metal with other metal halides on the other hand.
[0078] In summary, this invention enables the energy density of a three-dimensional porous lithium electrode to reach 99% of that of commercial lithium electrodes, and the open pore structure design inside the electrode provides sufficient space for lithium metal deposition, achieving zero volume change during electrode cycling. The resulting porous lithium metal or lithium alloy anode material can significantly improve the electrochemical performance of lithium metal batteries at high current densities, which is of great significance for the practical application of lithium metal batteries.
[0079] The above-described specific implementations can be partially adjusted by those skilled in the art in different ways without departing from the principles and purpose of the present invention. The scope of protection of the present invention is defined by the claims and is not limited to the above-described specific implementations. All implementation schemes within the scope of the claims are bound by the present invention.
Claims
1. A method for preparing porous lithium and its alloys into porous materials, characterized in that, First, the foaming agent is thoroughly mixed with metallic lithium or lithium alloy. Then, the mixture is heated in an orderly manner, starting from room temperature and increasing the temperature at 1℃ / min to 20℃ / min until it reaches 100℃ to 800℃. The temperature is then maintained for 1 to 600 minutes, and finally, it is allowed to cool naturally to room temperature. The mixed lithium metal or lithium alloy is heated to a molten state. The foaming agent decomposes under heat and releases gas, which generates a three-dimensional porous structure in the melt. After the melt cools and solidifies, a porous material is obtained. The thorough mixing refers to: rolling lithium metal or lithium alloy to obtain foil, and then uniformly mixing it with a uniformly sized foaming agent obtained by ball milling or recrystallization through rolling. The mass ratio of the foil to the foaming agent is 20:1 to 100:1; The foaming agent used is azodicarbonamide.
2. The method for preparing porous lithium and its alloys according to claim 1, characterized in that, The lithium alloy is LiM, wherein M is Na, K, Mg, Zn, Ca, Sn, Si, Ag, Au, Al, In, Bi or a combination thereof. It is obtained by mixing metallic lithium with other metals, melting and heating it under an inert atmosphere and then cooling it to room temperature, or by mixing metallic lithium with other metals and then rolling it.
3. A method for preparing a lithium battery electrode based on a porous material obtained by the method of claim 1 or 2, characterized in that, A porous lithium battery electrode supported by an alloy framework was obtained by immersing porous materials in a metal halide solution to modify the alloy interface layer. The metal halide solution mentioned refers to InCl3.
4. A lithium battery electrode prepared according to the method of claim 3, characterized in that, From the outside in, it includes: a lithium or lithium alloy phase, a self-supporting porous structure of the lithium or lithium alloy electrode, and an interface modification layer on the electrode surface and inside the bulk phase. The lithium alloy phase serves as a lithiophilic site during the lithium deposition process, the porous structure of the lithium or lithium alloy electrode provides a space for the deposited metallic lithium, and the interface modification layer on the electrode surface and inside the bulk phase provides interface protection and a fast ion migration interface for the electrode.
5. An application based on the lithium battery electrode of claim 4, characterized in that, It is used as a negative electrode material, matched with the positive electrode and electrolyte, to assemble a high-energy-density lithium metal battery. The positive electrode includes: an embedded positive electrode, a conversion positive electrode, or an embedded / conversion composite positive electrode.