Elastic eutectic alloy negative electrode and preparation method and application thereof

Abstract

The invention relates to a preparation method of an elastic eutectic alloy negative electrode, the elastic eutectic alloy negative electrode is prepared by compounding lithium metal and an elastic eutectic alloy, the elastic eutectic alloy is prepared from a component I and a component II, the component I is one or two of metal Mg, Al, Zn, Ga, Ag, In, Sn, Sb and Bi and nonmetal Si, the component II is one or two of metal Ca, Ti, Cr, Mn, Fe, Ni, Cu, Ge, Zr, Nb, Mo and Au, and the component II is one or two of metal Ca, Ti, Cr, Mn, Fe, Ni, Cu, Ge, Zr, Nb, Mo and Au. The types of metals in the components of the elastic eutectic alloy are not more than three. The invention also relates to the elastic eutectic alloy negative electrode prepared by the preparation method and application of the elastic eutectic alloy negative electrode in a bipolar solid-state battery. The elastic eutectic alloy negative electrode can effectively reduce the nucleation potential barrier of lithium metal, induce uniform deposition of lithium and buffer mechanical contact stress, so that volume expansion in the charging and discharging process is relieved, and assembly layering induced by pulverization and volume fluctuation is inhibited.

Description

TECHNICAL FIELD

[0001] The present application relates to a flexible eutectic alloy negative electrode and a preparation method and application thereof, and belongs to the technical field of alloy materials and their applications. BACKGROUND

[0002] The rapid development of the global energy field puts forward application requirements of high energy density (>500 Wh / kg) and wide temperature range scenarios (-40℃~80℃) for lithium secondary batteries. At present, the low theoretical specific capacity of traditional negative electrode materials represented by carbon materials has become a bottleneck restricting the energy density, and the limited ion / electron transmission at low temperature exacerbates the polarization phenomenon and lithium precipitation behavior. Lithium metal is expected to become the preferred negative electrode of the next generation of high-energy density solid-state batteries due to its low electrochemical potential (-3.04V relative to the standard hydrogen electrode) and high theoretical specific capacity (3860 mAh / g).

[0003] Lithium metal negative electrode has extremely high thermodynamic instability, and continuously spontaneous reduction reaction occurs with the electrolyte. At the same time, the lithium deposition / dissolution process lacks lattice skeleton constraint, and its nucleation and growth has high spatial randomness, which causes uneven lithium deposition and uncontrollable volume expansion, resulting in continuous reduction of the coulombic efficiency of the battery and micro-short circuit, which seriously hinders the practical application of lithium metal negative electrode in solid-state batteries. In order to solve the above two key problems of lithium metal negative electrode, the current solution strategy mainly starts from optimizing the compatibility of electrolyte / lithium metal negative electrode, artificially constructing an interface protection layer, and designing a three-dimensional porous current collector. Although these technical means can improve the electrochemical performance of lithium metal batteries to some extent, they are difficult to effectively overcome the intrinsic defects of lithium metal negative electrode, and the research results are difficult to be popularized and applied on a commercial scale. SUMMARY

[0004] In order to overcome the above-mentioned defects of the prior art, the present application provides a flexible eutectic alloy negative electrode and a preparation method and application thereof, which can effectively reduce the nucleation barrier of lithium metal, induce uniform lithium deposition, buffer mechanical contact stress, and further relieve volume expansion during charging and discharging, inhibit pulverization, and improve the problem of continuous reduction of coulombic efficiency and micro-short circuit of lithium metal negative electrode in practical application.

[0005] The technical solution adopted in this invention is: a method for preparing an elastic eutectic alloy anode, wherein lithium metal is combined with an elastic eutectic alloy to prepare an elastic eutectic alloy anode, wherein the mass ratio of lithium metal to the elastic eutectic alloy in the elastic eutectic alloy anode is 1:1.05~1:100; the elastic eutectic alloy is prepared by using component one and component two, wherein component one is one or two of the following metals: Mg, Al, Zn, Ga, Ag, In, Sn, Sb, Bi and non-metal Si, and component two is one or two of the following metals: Ca, Ti, Cr, Mn, Fe, Ni, Cu, Ge, Zr, Nb, Mo and Au, wherein the number of metals in the components of the elastic eutectic alloy does not exceed three, and the mass ratio of component one to component two is 1.5:1~100:1.

[0006] Preferably, both component one and component two are made of elemental powder materials with a purity of ≥99.99%.

[0007] Preferably, the lithium metal is composited with the elastic eutectic alloy by melt infusion, electrochemical lithiation, or physical imprinting.

[0008] Preferably, when component one uses two components (or materials), the mass ratio of the two components is 1.5:1 to 50:1; when component two uses two components (or materials), the mass ratio of the two components is 1:1 to 30:1.

[0009] Preferably, the raw materials for preparing the elastic eutectic alloy further include a space-retaining agent, which is urea, ammonium bicarbonate or PMMA microspheres. The mass ratio between the space-retaining agent and the total mass of component one and component two (the sum of the masses of component one and component two) is 1:40 to 3:2, that is, the mass ratio between the space-retaining agent and the mixed powder material composed of component one and component two is 1:40 to 3:2.

[0010] Preferably, in the composite process of the lithium metal and the elastic eutectic alloy, the elastic eutectic alloy serves as the substrate framework for the lithium metal deposition, and component one in the elastic eutectic alloy undergoes a lithium alloying reaction with the lithium metal to form an intermetallic compound or a solid solution alloy.

[0011] Preferably, the method for preparing the elastic eutectic alloy includes the following steps: Step 1, Material Preparation: Select the component materials required for preparing the elastic eutectic alloy, and prepare the materials according to the mass ratio of each component material. The component materials are powder materials. Step 2, Mixing: Place the prepared components into a mixer and mix them evenly to obtain a powder mixture; Step 3, Powder compaction: The powder mixture is placed in a mold and pressed to form a eutectic alloy green compact; Step 4, alloy preparation: The eutectic alloy green billet is placed in an electromagnetic induction heating device. Under the action of the induced current, the interior of the eutectic alloy green billet is immediately (within 30 seconds) heated to the eutectic temperature of the alloy. After maintaining the temperature for a certain period of time, the power is turned off and the billet is cooled to obtain the elastic eutectic alloy.

[0012] Preferably, the material preparation in step one is carried out in a dry room with a dew point below -40°C.

[0013] Preferably, in step two, after placing each component material into the mixer, an inert gas is introduced into the mixer as a protective gas. After the inert gas in the mixer is repeatedly replaced several times, an inert gas is introduced into the mixer again to maintain a slight positive pressure of no more than 0.05 MPa in the mixer. The mixing speed and duration are set to mix each component material.

[0014] The inert gas can be high-purity argon (purity ≥ 99.999%), high-purity nitrogen (purity ≥ 99.999%), or high-purity helium (purity ≥ 99.999%).

[0015] Preferably, the inert gas in the mixer is replaced 2-3 times, using either a pressure relief method or a vacuum replacement method.

[0016] Preferably, after the inert gas is refilled into the mixer, the positive pressure maintained inside the mixer is 0.02MPa~0.05MPa.

[0017] Preferably, the mixing speed of the mixer is 5 r / min to 20 r / min, and the mixing time is 15 min to 60 min.

[0018] The mixer can be a three-dimensional mixer, a V-type mixer, or a double-cone mixer.

[0019] Preferably, in step three, the mold is a square mold, the pressure for pressing the powder mixture is 100MPa~500MPa, and the holding time is 10s~60s.

[0020] Preferably, in step four, the eutectic temperature is determined based on the phase diagram of the elastic eutectic alloy system combined with differential scanning calorimetry.

[0021] Preferably, in step four, after the eutectic alloy green billet is placed in the electromagnetic induction heating device, an inert gas is introduced into the electromagnetic induction heating device as a protective gas. The inert gas can be argon, and the purity of the argon is ≥99.999%.

[0022] Preferably, in step four, the electromagnetic induction heating temperature range of the electromagnetic induction heating device is 300℃~900℃, and the constant temperature duration is 10s~300s.

[0023] The electromagnetic induction heating device can be an electromagnetic heater.

[0024] Preferably, in step four, the cooling method is natural controlled-rate cooling or gas quenching cooling, and the cooling time is 1h to 20h. When natural controlled-rate cooling is used, the cooling rate is 1℃ / min to 5℃ / min. When gas quenching cooling is used, an inert gas is used, which can be argon gas with a purity ≥99.999% and a gas pressure of 0.2MPa to 1MPa.

[0025] The elastic eutectic alloy anode is prepared using any of the preparation methods for elastic eutectic alloy anodes disclosed in this invention.

[0026] The application of any of the elastic eutectic alloy anodes disclosed in this invention in bipolar solid-state batteries.

[0027] The bipolar solid-state battery is a mold battery or a pouch battery, comprising a composite positive electrode, an electrolyte, and the elastic eutectic alloy negative electrode. The active material of the composite positive electrode includes one or more of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium-rich manganese-based oxide, lithium iron phosphate, and lithium nickel cobalt aluminum oxide. The electrolyte includes one or more of polymer solid electrolyte, sulfide solid electrolyte, oxide solid electrolyte, and halide solid electrolyte.

[0028] The beneficial effects of this invention are: (1) The elastic eutectic alloy anode prepared by the preparation method of the present invention exhibits controllable porosity, excellent plastic deformation ability and yield behavior, which can effectively buffer the mechanical contact stress during the cycle process, optimize the interface contact, thereby alleviate the volume expansion during the charging and discharging process, suppress the component delamination induced by pulverization and volume fluctuation, and effectively reduce the nucleation barrier of lithium metal, induce uniform lithium deposition, achieve uniform current density distribution, suppress the growth of lithium dendrites, improve the problem of continuous reduction of coulombic efficiency and micro short circuit in the practical application of lithium metal anode, help improve the cycle life and power density of battery, and promote the application of high safety and high energy density lithium metal battery; (2) The present invention innovatively constructs a three-dimensional elastic eutectic alloy substrate framework in the negative electrode, providing a structured fast transport path for lithium ions, significantly improving the mass transfer dynamics inside the electrode, and still achieving fast and stable charging and discharging under extreme low temperature conditions; (3) The preparation method of the elastic eutectic alloy of the present invention is simple, efficient, highly adjustable, and has good potential for large-scale production. It can be further extended to the preparation and application of other metal alloys such as sodium and zinc. Attached Figure Description

[0029] Figure 1 This is a flowchart of the preparation method of the elastic eutectic alloy negative electrode of the present invention; Figure 2 This is a SEM image of the elastic eutectic alloy negative electrode of Embodiment 1 of the present invention; Figure 3 This is a comparison chart of the low-temperature critical current density test results of symmetrical batteries assembled with alloy negative electrodes prepared according to Example 1 and Comparative Example 1 of the present invention. Figure 4 The symmetrical battery assembled using the alloy negative electrode prepared in Example 1 and Comparative Example 1 of this invention operates at a current density of 1 mA·cm⁻¹. -2 The deposition surface capacity is 1 mAh·cm³. -2 Comparison of low-temperature long-cycle performance under certain conditions; Figure 5 This is a schematic diagram of one embodiment of the bipolar solid-state battery of the present invention; Figure 6 This is a comparison chart of the cycle performance of bipolar solid-state batteries assembled using alloy negative electrodes prepared in Example 1 and Comparative Example 1 of the present invention. Detailed Implementation

[0030] See Figure 1This invention discloses a method for preparing an elastic eutectic alloy anode. The method involves combining lithium metal with an elastic eutectic alloy to prepare the anode. The mass ratio of lithium metal to the elastic eutectic alloy in the anode is 1:1.05 to 1:100. The elastic eutectic alloy is prepared using component one and component two. During the preparation process, component one and component two are heated by instantaneous electromagnetic induction. When the eutectic temperature is reached, a liquid film is formed at the interface between component one and component two. This liquid film greatly accelerates atomic migration and densification (i.e., sintering), thereby rapidly obtaining the elastic eutectic alloy at a temperature below the melting point of the main components. Component one is one or two of the following metals: Mg, Al, Zn, Ga, Ag, In, Sn, Sb, Bi, and non-metal Si. Component two is one or two of the following metals: Ca, Ti, Cr, Mn, Fe, Ni, Cu, Ge, Zr, Nb, Mo, Au. The number of metals in the components of the elastic eutectic alloy does not exceed three. The mass ratio of component one to component two is 1.5:1 to 100:1. Preferably, both component one and component two are made of elemental powder with a purity ≥99.99%. The lithium metal can be composited with the elastic eutectic alloy by melt infusion, electrochemical lithiation, or physical imprinting. During the composite process of lithium metal and the elastic eutectic alloy, the elastic eutectic alloy serves as the substrate framework for lithium metal deposition. Component one in the elastic eutectic alloy undergoes a lithium alloying reaction with the lithium metal to form an intermetallic compound or a solid solution alloy.

[0031] When component one uses two components, the mass ratio of the two components is 1.5:1 to 50:1 (referring to the mass ratio of the component with a relatively larger mass to the component with a relatively smaller mass); when component two uses two components, the mass ratio of the two components is 1:1 to 30:1.

[0032] The raw materials for preparing the elastic eutectic alloy preferably also include a space retention agent, which can be urea, ammonium bicarbonate or PMMA microspheres. The mass ratio of the space retention agent to the total mass of component one and component two is 1:40 to 3:2, for example, 1:40, 1:20, 1:10, 1:1 or 3:2.

[0033] A preferred method for preparing the elastic eutectic alloy includes the following steps: Step 1, Material Preparation: Select the component materials required for preparing the elastic eutectic alloy, and prepare the materials according to the mass ratio of each component material. The component materials are powder materials. Material preparation is preferably carried out in a dry room with a dew point below -40°C.

[0034] Step 2, Mixing: Place the prepared components into a mixer and mix them evenly to obtain a powder mixture; After placing each component material into the mixer, inert gas is introduced into the mixer as a protective gas. The inert gas in the mixer is repeatedly replaced several times. Then, inert gas is introduced into the mixer again to maintain a slight positive pressure of no more than 0.05 MPa. The mixing speed and duration are set to mix each component material.

[0035] The inert gas can be high-purity argon (purity ≥ 99.999%), high-purity nitrogen (purity ≥ 99.999%), or high-purity helium (purity ≥ 99.999%). The inert gas in the mixer is preferably replaced 2-3 times, using either a pressure-relief method or a vacuum replacement method. After refilling the mixer with inert gas, the positive pressure maintained inside the mixer is preferably 0.02 MPa to 0.05 MPa.

[0036] When replacing the inert gas using the pressurization and depressurization method, open the inert gas inlet valve and slowly pressurize the mixer drum until the pressure gauge reads 0.05MPa~0.1MPa. Close the inlet valve and slowly open the exhaust valve to discharge the gas from the drum until the pressure gauge reads 0MPa. Repeat the above steps 2~3 times to repeat the pressurization and depressurization process. When replacing the inert gas using the vacuum replacement method, turn on the vacuum pump and slowly extract the gas from the mixer drum until the pressure gauge reads -0.1MPa. Turn off the vacuum pump, open the inert gas inlet valve, and slowly pressurize the mixer drum until the pressure gauge reads 0MPa. Repeat the above steps 2~3 times to repeat the vacuuming and pressing process.

[0037] The mixing speed of the mixer is preferably 5 r / min to 20 r / min, and the mixing time is preferably 15 min to 60 min, to ensure thorough mixing of the components and suppress segregation. The mixer can be a three-dimensional mixer, a V-type mixer, or a double-cone mixer.

[0038] Step 3, Powder compaction: The powder mixture is placed in a mold and pressed to form a eutectic alloy green compact; The mold can be a square mold, and the pressure for pressing the powder mixture is preferably 100MPa~500MPa, and the holding time is preferably 10s~60s.

[0039] Step 4, alloy preparation: The eutectic alloy green billet is placed in an electromagnetic induction heating device. Under the action of the induced current, the interior of the eutectic alloy green billet is heated to the eutectic temperature of the alloy immediately (within 30 seconds). After maintaining the temperature for a certain period of time, the power is turned off and the billet is cooled to obtain the elastic eutectic alloy. The purpose of rapid sintering (immediate heating) is to cross the decomposition temperature range of the space retention agent in a very short time, so as to avoid premature decomposition and structural collapse when the strength of the blank is insufficient, improve the sintering driving force, obtain an elastic eutectic alloy with controllable pore structure, and help improve the mechanical and electrochemical properties of the alloy anode.

[0040] The preferred eutectic temperature is determined using a phase diagram of the elastic eutectic alloy system combined with differential scanning calorimetry (DSC). Specifically, the method involves reading the theoretical eutectic temperature corresponding to the eutectic point of the elastic eutectic alloy system from the phase diagram. A small amount (5-20 mg) of uniformly mixed component one and component two powders is placed in a high-purity alumina or boron nitride crucible, heated under inert gas protection, and a DSC curve is acquired. The endothermic peak corresponding to the eutectic reaction on the curve is used to determine the extrapolated onset temperature using the tangent method, which is then taken as the accurate eutectic temperature.

[0041] After placing the eutectic alloy green billet in an electromagnetic induction heating device, it is preferable to introduce an inert gas as a protective gas into the device. The inert gas can be argon, with a purity ≥99.999%. The electromagnetic induction heating temperature range of the device is preferably 300℃~900℃, and the holding time is preferably 10s~300s. The electromagnetic induction heating device can be an electromagnetic heater.

[0042] Cooling can be achieved through natural controlled-rate cooling or gas quenching, with a preferred cooling time of 1 to 20 hours. When natural controlled-rate cooling is used, the preferred cooling rate is 1°C / min to 5°C / min. When gas quenching is used, an inert gas is employed, such as argon, with a purity ≥99.999% and a preferred gas pressure of 0.2 MPa to 1 MPa. This ensures maximum heat exchange efficiency while maintaining a refined and stable eutectic structure.

[0043] The present invention also discloses an elastic eutectic alloy anode, which is prepared by any of the preparation methods of the elastic eutectic alloy anode disclosed in the present invention.

[0044] This invention also discloses the application of the elastic eutectic alloy anode in bipolar solid-state batteries. The bipolar solid-state battery is a mold battery or a pouch battery, comprising a composite cathode, an electrolyte, and the elastic eutectic alloy anode. The active material of the composite cathode includes one or more of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium-rich manganese-based oxide, lithium iron phosphate, and lithium nickel cobalt aluminum oxide. The electrolyte includes one or more of polymer solid electrolytes, sulfide solid electrolytes, oxide solid electrolytes, and halide solid electrolytes.

[0045] Example 1 (taking Al-Cu-Mg as an example of an elastic eutectic alloy system): S1: Material preparation: In a dry room with a dew point below -40℃, weigh Al, Cu, and Mg powders in a mass ratio of 64:30.5:5.5, and weigh PMMA microspheres with a mass fraction of 3% as a space retention agent.

[0046] S2: Mixing: Transfer the above powder materials to the three-dimensional motion mixer, with the loading volume not exceeding 50% of the effective volume of the three-dimensional mixer; close all ports of the mixer to ensure it is in a sealable state; fill the three-dimensional mixer with high-purity argon as an inert protective gas; repeat the high-purity argon replacement three times using the pressure-relief method; after the last pressure relief, fill the three-dimensional mixer with high-purity argon again to maintain a positive pressure of 0.05 MPa inside the three-dimensional mixer, keeping the inlet valve slightly open; set the mixing speed of the three-dimensional mixer to 10 r / min and the mixing time to 30 min; start the three-dimensional mixer to mix the powder materials evenly to obtain a powder mixture.

[0047] S3: Powder compaction: The mixed powder mixture is taken out from the three-dimensional mixer and quickly transferred to a square mold. A pressure of 200MPa is applied and the pressure is held for 30s to form a eutectic alloy green compact.

[0048] S4: Preparation of elastic eutectic alloy: The eutectic alloy green billet is transferred to an electromagnetic induction heating device. High-purity argon gas is introduced into the electromagnetic induction heating device as an inert protective gas. The heating temperature is set to 500℃ (eutectic temperature). The electromagnetic induction heating device is started and the temperature is immediately raised to this temperature. After holding the temperature for 60 seconds, the power is immediately cut off and high-purity argon gas is continuously introduced for gas quenching and cooling. The gas pressure is set to 0.4MPa and the flow rate is turned on to the maximum to obtain the elastic eutectic alloy.

[0049] S5: Preparation of Elastic Eutectic Alloy Anode: Lithium metal was heated to 350℃ to obtain molten lithium, which was then poured into the top of the elastic eutectic alloy. During the lithium metal impregnation and filling process, Li-Al and Li-Mg alloying reactions occurred simultaneously to obtain the elastic eutectic alloy anode. Its SEM image is shown below. Figure 2 As shown, the mass percentage of lithium in the elastic eutectic alloy anode is 10%.

[0050] Example 2 (taking Mg-Al-Ca as an example of an elastic eutectic alloy system): The difference between this embodiment and Embodiment 1 is that: In step S1, Mg, Al, and Ca powders are weighed in a mass ratio of 94:3.5:2.5.

[0051] In step S4, the heating temperature is set to 510℃.

[0052] In step S5, during the lithium metal impregnation and filling process, Li-Mg and Li-Al alloying reactions occur simultaneously.

[0053] Apart from the differences mentioned above, the other preparation steps and methods are the same as in Example 1.

[0054] Example 3 (taking Mg-Zn-Ca as an example of an elastic eutectic alloy system): The difference between this embodiment and Embodiment 1 is that: In step S1, Mg, Zn, and Ca powders are weighed in a mass ratio of 94.5:4:1.5.

[0055] In step S4, the heating temperature is set to 340°C.

[0056] In step S5, during the lithium metal impregnation and filling process, Li-Mg and Li-Zn alloying reactions occur simultaneously.

[0057] Apart from the differences mentioned above, the other preparation steps and methods are the same as in Example 1.

[0058] Example 4 (taking Al-Cu as an example of an elastic eutectic alloy system): The difference between this embodiment and Embodiment 1 is that: In step S1, Al and Cu powders are weighed in a mass ratio of 66.8:33.2.

[0059] In step S4, the heating temperature is set to 540℃.

[0060] In step S5, during the lithium metal impregnation and filling process, a Li-Al alloying reaction occurs simultaneously.

[0061] Apart from the differences mentioned above, the other preparation steps and methods are the same as in Example 1.

[0062] Example 5: The difference between this embodiment and Embodiment 1 is that: In step S1, the space retention agent is urea with a mass fraction of 3.3%.

[0063] Apart from the differences mentioned above, the other preparation steps and methods are the same as in Example 1.

[0064] The elastic eutectic alloy anode prepared in Example 5 can achieve essentially the same effect as the elastic eutectic alloy anode prepared in Example 1.

[0065] Example 6: The difference between this embodiment and Embodiment 1 is that: In step S2, the powder material is mixed using a V-type mixer, and the inert gas (protective gas) is repeatedly replaced using a vacuum displacement method.

[0066] Apart from the differences mentioned above, the other preparation steps and methods are the same as in Example 1.

[0067] The elastic eutectic alloy anode prepared in Example 6 can achieve essentially the same effect as the elastic eutectic alloy anode prepared in Example 1.

[0068] Example 7: The difference between this embodiment and Embodiment 1 is that: In step S5, the lithium metal is impregnated and filled using physical imprinting.

[0069] Apart from the differences mentioned above, the other preparation steps and methods are the same as in Example 1.

[0070] The elastic eutectic alloy anode prepared in Example 7 can achieve essentially the same effect as the elastic eutectic alloy anode prepared in Example 1.

[0071] Comparative Example 1: The difference between this comparative example and Example 1 is as follows: In step S4, the heating temperature is set to 650°C, which is higher than the eutectic temperature of the Al-Cu-Mg alloy.

[0072] Apart from the differences mentioned above, the other preparation steps and methods are the same as in Example 1.

[0073] Comparative Example 2: The difference between this comparative example and Example 1 is as follows: In step S4, the eutectic alloy green billet is heated by a tube furnace with a heating rate of 5°C / min, gradually increasing to 500°C, and then quenched in air to obtain the Al-Cu-Mg alloy.

[0074] Apart from the differences mentioned above, the other preparation steps and methods are the same as in Example 1.

[0075] Symmetrical cells were assembled using the elastic eutectic alloy anode prepared in Example 1 and the alloy anode prepared in Comparative Example 1, respectively. Critical current density tests were conducted under low-temperature conditions, with a current density of 1 mA·cm⁻¹. -2 The deposition surface capacity is 1 mAh·cm³. -2 The following long-loop test was performed, and the test results are as follows: Figure 3 and Figure 4 As shown, the critical current density of the symmetrical battery assembled using the elastic eutectic alloy anode prepared in Example 1 can reach 4 mA·cm⁻¹. -2 1mA·cm -2 It can cycle stably for 1400 hours. The elastic eutectic alloy anode can still achieve rapid and stable lithium deposition / stripping under low temperature conditions, with excellent interface contact and compatibility, effectively inducing uniform lithium deposition and suppressing lithium dendrite growth.

[0076] Bipolar solid-state mold batteries were assembled using the elastic eutectic alloy anode 1 prepared in Example 1 and the alloy anode prepared in Comparative Example 1, respectively, along with Li6PS5Cl silver-germanium sulfide electrolyte 2 and lithium nickel cobalt-manganese oxide cathode 3. Stainless steel 4 was used as the outer casing. The structure of the bipolar solid-state mold battery assembled using the elastic eutectic alloy anode prepared in Example 1 is as follows: Figure 5 As shown. The charge-discharge cycle test data of bipolar solid-state mold batteries assembled using the elastic eutectic alloy anode 1 prepared in Example 1 and the alloy anode prepared in Comparative Example 1 are as follows. Figure 6 As shown in the figure, the bipolar solid-state mold battery assembled with the elastic eutectic alloy anode prepared in Example 1 exhibits significantly improved cycle stability compared to the bipolar solid-state mold battery assembled with the alloy anode prepared in Comparative Example 1.

[0077] The elastic eutectic alloy anodes or alloy anodes prepared in each embodiment and comparative example were used to assemble bipolar solid-state batteries with Li6PS5Cl silver-germanium sulfide electrolyte and lithium nickel cobalt-manganese oxide cathode, and charge-discharge cycle tests were conducted. The cycle performance is summarized in Table 1.

[0078] Table 1. Cycle count and capacity retention of bipolar solid-state batteries assembled with negative electrodes obtained using each embodiment and comparative example.

[0079] As shown in Table 1, the bipolar solid-state battery assembled with the elastic eutectic alloy anode prepared in each embodiment still has a higher capacity retention rate than the bipolar solid-state battery assembled with the alloy anode prepared in each comparative example, even when the number of cycles is increased by about two times.

[0080] This invention proposes an innovative alloy anode preparation strategy that can provide a structured and rapid transport path for lithium ions, effectively reduce the nucleation barrier of lithium metal, induce uniform lithium deposition, buffer mechanical contact stress, and suppress alloy anode pulverization. This, in turn, alleviates volume expansion and component delamination during charging and discharging, providing an effective solution for solid-state batteries with long lifespan, high safety, and extreme operating conditions.

[0081] Unless otherwise specified or further limited to one preferred or optional technical means being another, the preferred and optional technical means disclosed in this invention can be arbitrarily combined to form several different technical solutions.

[0082] Any method for preparing an elastic eutectic alloy anode of the present invention, or any elastic eutectic alloy anode, can be used in any bipolar solid-state battery of the present invention.

[0083] Any bipolar solid-state battery of the present invention can also be prepared using any of the elastic eutectic alloy anode preparation methods of the present invention or any of the elastic eutectic alloy anodes.

Claims

1. A method for preparing an elastic eutectic alloy negative electrode, characterized in that... An elastic eutectic alloy anode is prepared by combining lithium metal with an elastic eutectic alloy. In the elastic eutectic alloy anode, the mass ratio of lithium metal to the elastic eutectic alloy is 1:1.05 to 1:

100. The elastic eutectic alloy is prepared by using component one and component two. Component one is one or two of the following metals: Mg, Al, Zn, Ga, Ag, In, Sn, Sb, Bi, and non-metal Si. Component two is one or two of the following metals: Ca, Ti, Cr, Mn, Fe, Ni, Cu, Ge, Zr, Nb, Mo, and Au. The number of metals in the components of the elastic eutectic alloy does not exceed three. The mass ratio of component one to component two is 1.5:1 to 100:

1.

2. The method for preparing the elastic eutectic alloy negative electrode according to claim 1, characterized in that... The lithium metal is composited with the elastic eutectic alloy by melt infusion, electrochemical lithiation, or physical imprinting.

3. The method for preparing the elastic eutectic alloy negative electrode according to claim 1, characterized in that... When component one uses two components, the mass ratio of the two components is 1.5:1 to 50:1; when component two uses two components, the mass ratio of the two components is 1:1 to 30:

1.

4. The method for preparing the elastic eutectic alloy negative electrode according to claim 1, characterized in that... The raw materials for preparing the elastic eutectic alloy also include a space retention agent, which is urea, ammonium bicarbonate or PMMA microspheres, and the ratio of the mass of the space retention agent to the total mass of component one and component two is 1:40 to 3:

2.

5. The method for preparing the elastic eutectic alloy negative electrode according to claim 1, characterized in that... During the composite process of the lithium metal and the elastic eutectic alloy, component one of the elastic eutectic alloy undergoes a lithium alloying reaction with the lithium metal to form an intermetallic compound or a solid solution alloy.

6. The method for preparing the elastic eutectic alloy negative electrode according to any one of claims 1-5, characterized in that... The preparation method of the elastic eutectic alloy includes the following steps: Step 1, Material Preparation: Select the component materials required for preparing the elastic eutectic alloy, and prepare the materials according to the mass ratio of each component material. The component materials are powder materials. Step 2, Mixing: Place the prepared components into a mixer and mix them evenly to obtain a powder mixture; Step 3, Powder compaction: The powder mixture is placed in a mold and pressed to form a eutectic alloy green compact; Step 4, alloy preparation: Place the eutectic alloy green billet in an electromagnetic induction heating device, immediately heat it to the eutectic temperature of the alloy, keep it at a constant temperature for a certain period of time, then turn off the power to cool it down, and obtain the elastic eutectic alloy.

7. The method for preparing the elastic eutectic alloy negative electrode according to claim 6, characterized in that... The eutectic temperature is determined based on the phase diagram of the elastic eutectic alloy system combined with differential scanning calorimetry.

8. The method for preparing the elastic eutectic alloy negative electrode according to claim 6, characterized in that... In step two, after placing each component material into the mixer, inert gas is introduced into the mixer. After the inert gas in the mixer is repeatedly replaced several times, inert gas is introduced into the mixer again and the positive pressure inside the mixer is maintained at no more than 0.05 MPa. The mixing speed and duration are set to mix each component material.

9. An elastic eutectic alloy negative electrode, characterized in that... The anode is prepared using the method described in any one of claims 1-8.

10. The application of the elastic eutectic alloy anode according to claim 9 in a bipolar solid-state battery.

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