Rare-earth-based lithium alloy negative electrode material as well as preparation method and application thereof

Abstract

The invention discloses a rare earth-based lithium alloy negative electrode material and a preparation method and application thereof, and the preparation method comprises the following steps: S1, mechanically mixing rare earth and an active material to obtain a rare earth-active material mixture; s2, calcining the rare earth-active material mixture obtained in the step S1 at 500-1500 DEG C for 1-10 hours to obtain a rare earth-based alloy material; s3, lithium metal and the rare earth-based alloy material obtained in the step S2 are mechanically mixed, and a rare earth-based lithium alloy material is obtained; wherein the molar ratio of the rare earth to the active material to the lithium metal is (1-50): (1-99): (1-99). The rare-earth-based lithium alloy material can be obtained by combining a high-temperature solid-phase method and a mechanical mixing method, the rare-earth-based lithium alloy material is applied to a lithium battery as a negative electrode, dendritic crystal growth can be inhibited to a certain extent, and the cycling stability of the battery is improved.

Description

Technical Field

[0001] The present invention relates to a rare earth-based lithium alloy anode material, a preparation method thereof, and an application thereof, belonging to the technical field of lithium batteries. Background Art

[0002] With the proposal of the dual-carbon goal, China has vigorously promoted the development of green and low-carbon industries such as wind / solar power generation and new energy vehicles, and the storage and utilization of electric energy is a key link that supports the development of the new energy industry. Among many energy storage devices, lithium batteries have the advantages of long cycle life and high energy density, and are the most widely used.

[0003] A lithium battery usually consists of three parts: an anode, an electrolyte, and a cathode. The storage and release of electric energy are carried out through the movement of lithium ions between the electrodes. Among them, the properties of the anode can affect the overall performance of the battery. For example, during the charge and discharge process of a lithium battery, uncontrollable dendrite problems often occur on the anode side, which reduces the cycle life of the battery and may even cause short circuits, posing safety risks such as combustion and explosion. In addition, the volume change of the anode material during the charge and discharge process and the side reaction with the electrolyte will increase the internal resistance of the battery and reduce the battery capacity. To address the above problems, researchers often use lithium-based alloys as the battery anode, which can promote the uniform deposition of lithium ions. However, the volume change during the insertion and extraction of lithium ions in the lithium-based alloy anode is also obvious.

[0004] In view of the above problems, this application is specifically proposed. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a class of rare earth-based lithium alloy anode materials and apply them in lithium batteries, solving the problem that the stability of the lithium battery anode needs to be optimized.

[0006] The first object of the present invention is to provide a preparation method of a rare earth-based lithium alloy anode material, including the following steps:

[0007] S1: Mechanically mix rare earths with active materials to obtain a rare earth-active material mixture;

[0008] S2: Calcinate the rare earth-active material mixture obtained in step S1 at 500-1500 °C for 1-10 h to obtain a rare earth-based alloy material;

[0009] S3: Mechanically mix lithium metal with the rare earth-based alloy material obtained in step S2 to obtain a rare earth-based lithium alloy material;

[0010] Wherein, the molar ratio of the rare earths, active materials, and lithium metal is 1-50:1-99:1-99.

[0011] Preferably, the molar ratio of the active material, lithium metal is 1-4:10-18:4-10.

[0012] Preferably, the rare earth includes one or more of scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium.

[0013] Preferably, the lithium metal is one or more of lithium blocks, lithium sheets, lithium powders.

[0014] Preferably, the active material includes alloy-type negative electrodes indium, tin, aluminum, magnesium, silicon, germanium, antimony, bismuth and one or more of carbon-based negative electrodes graphite, graphene, hard carbon, soft carbon.

[0015] Preferably, the mechanical mixing in step S1 is the repeated cold pressing method, the manual grinding method or the mechanical ball milling method. The repeated cold pressing method is to cold press the rare earth and the active material into sheets repeatedly for multiple times, the pressure is 2-4t, and the number of cold pressing repetitions is 5-20 times. The manual grinding method is to mix the rare earth and the active material in a mortar, and the grinding time is 5-30min. The mechanical ball milling method is to use a ball mill to mix the rare earth and the active material, the ball milling speed is 200-500r / min, and the ball milling time is 1-10h.

[0016] Adopting the above technical solution, for sheet-like or block-like active materials with good ductility, such as indium, tin, etc., it is preferred to use the repeated cold pressing method to mix the rare earth and the active material; for powdered active materials, it is preferred to use the manual grinding or mechanical ball milling method to mix the rare earth and the active material.

[0017] Preferably, the rare earth-active material mixture is calcined at 700-1000°C for 4-6h in step S2.

[0018] Adopting the above technical solution, the physical forms of the rare earth, active material, and lithium metal used in the present invention are powdered, sheet-like or block-like. Among them, the particle sizes of the powdered rare earth, active material, and lithium metal are 10-10000 mesh, preferably 100-1000 mesh.

[0019] In step S3, the mechanical mixing of the lithium metal and the rare earth-based alloy material includes repeated cold pressing, manual grinding or mechanical ball milling. For lithium sheets or lithium blocks, it is preferred to use the repeated cold pressing method to mix the lithium metal and the rare earth-based alloy material. For lithium powders, it is preferred to use the manual grinding or mechanical ball milling method to mix the lithium metal and the rare earth-based alloy material.

[0020] The second object of the present invention is to provide the rare earth-based lithium alloy negative electrode material prepared by the above method, and the rare earth-based lithium alloy negative electrode material is block-like or powdered.

[0021] The third object of the present invention is to provide the application of the above rare earth-based lithium alloy anode material in a lithium battery, including an anode, an electrolyte and a cathode, wherein the anode is the rare earth-based lithium alloy anode material.

[0022] Preferably, the anode is one or both of a massive rare earth-based alloy material and a powdered rare earth-based alloy material.

[0023] Preferably, the electrolyte includes one or both of a liquid electrolyte and a solid electrolyte. The liquid electrolyte includes one or both of a carbonate-based electrolyte and an ether-based electrolyte. The solid electrolyte includes one or more of a polymer electrolyte, an oxide electrolyte, a sulfide electrolyte, and a halide electrolyte.

[0024] Preferably, the cathode includes 10%-90% of a cathode active material, 0-70% of a solid electrolyte, 0-20% of a carbon material, and 0-10% of a binder. The cathode active material includes one or more combinations of a lithium-containing cathode or a lithium-free cathode. The carbon material includes one or more combinations of acetylene black, Ketjen black, carbon nanotubes, graphite, graphene, soft carbon, hard carbon, activated carbon, and carbon fiber.

[0025] Preferably, the binder is one or more of polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), polyacrylic acid (PAA), polyacrylonitrile (PAN), polyethylene oxide (PEO), and polyacrylate.

[0026] Adopting the above technical solution, the massive rare earth-based alloy material needs to be cold-pressed into flakes, with a pressure of 1-5t, preferably 3-4t, and a thickness of 100-200μm. The powdered rare earth-based alloy material needs to be mixed with a binder and made into a rare earth-based alloy film by rolling or rolling, with a mass of 10-20mg / cm 2 , and a thickness of 100-200μm.

[0027] The beneficial effects of the present invention:

[0028] (1) The present invention combines the high-temperature solid-phase method and the mechanical mixing method to obtain a rare earth-based lithium alloy material. When used as an anode in a lithium battery, it can, to a certain extent, inhibit dendrite growth and improve the cycle stability of the battery.

[0029] (2) Rare earth elements have large sizes and small electronegativities, which can stabilize the structure of the anode material, limit the volume change during charge and discharge, and at the same time can guide the uniform deposition of lithium ions, showing great application potential in lithium-based alloy anodes. Description of the Drawings

[0030] Figure 1It is the charge-discharge cycle performance of the lithium battery in Embodiment 1 of the present invention, where the negative electrode is a cerium-indium-lithium alloy.

[0031] Figure 2 It is the charge-discharge cycle performance of the lithium battery in Comparative Example 1 of the present invention, where the negative electrode is an indium-lithium alloy.

[0032] Figure 3 It is the charge-discharge cycle performance of the lithium symmetric battery in Embodiment 2 of the present invention, where the electrode is a cerium-indium-lithium alloy.

[0033] Figure 4 It is the charge-discharge cycle performance of the lithium symmetric battery in Comparative Example 2 of the present invention, where the electrode is a magnesium-indium-lithium alloy.

[0034] Figure 5 It is the SEM image of the lanthanum-tin-lithium alloy in Embodiment 3 of the present invention.

[0035] Figure 6 It is the SEM image of the tin-lithium alloy in Comparative Example 3 of the present invention.

[0036] Figure 7 It is the electrochemical impedance spectrum of the lithium symmetric battery in Embodiment 4 of the present invention, where the electrode is a lanthanum-tin-lithium alloy.

[0037] Figure 8 It is the electrochemical impedance spectrum of the lithium symmetric battery in Comparative Example 4 of the present invention, where the electrode is a zinc-tin-lithium alloy.

[0038] Figure 9 It is the charge-discharge curve of the lithium battery in Embodiment 5 of the present invention, where the electrode is a yttrium-aluminum-lithium alloy.

[0039] Figure 10 It is the charge-discharge curve of the lithium battery in Comparative Example 5 of the present invention, where the electrode is an aluminum-lithium alloy.

[0040] Figure 11 It is the electrochemical impedance spectrum of the lithium symmetric battery in Embodiment 6 of the present invention, where the electrode is a yttrium-aluminum-lithium alloy.

[0041] Figure 12 It is the electrochemical impedance spectrum of the lithium symmetric battery in Comparative Example 6 of the present invention, where the electrode is a tin-aluminum-lithium alloy.

[0042] Figure 13 It is the electrochemical impedance spectrum of the lithium symmetric battery after cycling in Embodiment 7 of the present invention, where the electrode is a praseodymium-silicon-lithium alloy.

[0043] Figure 14 It is the electrochemical impedance spectrum of the lithium symmetric battery after cycling in Comparative Example 7 of the present invention, where the electrode is a silicon-lithium alloy.

[0044] Figure 15 It is the charge-discharge cycle performance of the lithium battery in Example 8 of the present invention, wherein the electrode is a praseodymium-silicon-lithium alloy.

[0045] Figure 16 It is the charge-discharge cycle performance of the lithium battery in Comparative Example 8 of the present invention, wherein the electrode is a praseodymium-silicon-lithium alloy.

[0046] Figure 17 It is the cycle performance of the lithium battery in Example 9 of the present invention, wherein the electrode is a yttrium-silicon-graphite-lithium alloy.

[0047] Figure 18 It is the cycle performance of the lithium battery in Comparative Example 9 of the present invention, wherein the electrode is a silicon-graphite-lithium alloy.

[0048] Figure 19 It is the charge-discharge cycle performance of the lithium battery in Example 10 of the present invention, wherein the electrode is a yttrium-silicon-graphite-lithium alloy.

[0049] Figure 20 It is the charge-discharge cycle performance of the lithium battery in Comparative Example 10 of the present invention, wherein the electrode is a tin-silicon-graphite-lithium alloy. Detailed implementation manners

[0050] To make the technical means, creative features, achieved purposes and effects of the present invention easy to understand, the present invention will be further described below in conjunction with specific implementation manners.

[0051] Example 1

[0052] (1) The preparation method of the cerium-indium-lithium alloy material is as follows:

[0053] Raw materials: cerium blocks, indium flakes and lithium metal flakes, and their molar ratio is 7:65:28.

[0054] First, the cerium blocks and indium flakes are repeatedly cold-pressed into a mixed metal block. Then, the mixed metal block is placed in a graphite crucible and calcined in an argon atmosphere for 5 h at a calcination temperature of 700 °C to obtain a cerium-indium alloy block. Subsequently, the lithium flakes and the cerium-indium alloy block are repeatedly cold-pressed and mixed to obtain a cerium-indium-lithium alloy.

[0055] (2) The lithium symmetric battery with the cerium-indium-lithium alloy material as the electrode is prepared as follows:

[0056] The electrolyte is a halide solid electrolyte (Li3YBr6); the electrode is a cerium-indium-lithium alloy sheet after cold pressing, the pressure is 4 t, and the thickness of the cerium-indium-lithium alloy sheet is 100-200 μm.

[0057] Weigh 100 mg of Li3YBr6 powder, place it in a circular mold, apply a pressure of 2 t to obtain an electrolyte sheet. Add cerium-indium-lithium alloy sheets on both sides of the electrolyte sheet, and apply a pressure of 4 t to obtain a lithium symmetric battery. Among them, the inner diameter of the circular mold is 10 mm, and the diameter of the cerium-indium-lithium alloy sheet is 10 mm.

[0058] (3) The lithium battery with a cerium-indium-lithium alloy material as the negative electrode is prepared as follows:

[0059] The electrolyte is a halide solid electrolyte (Li3YBr6); the negative electrode is a cold-pressed cerium-indium-lithium alloy sheet with a pressure of 4 t, and the thickness of the cerium-indium-lithium alloy sheet is 100 - 200 μm; the positive electrode is a mixture of lithium titanate, Li3YBr6, and Ketjen black, with a mass ratio of 2:7:1.

[0060] Weigh 100 mg of Li3YBr6 powder, place it in a circular mold, apply a pressure of 2 t to obtain an electrolyte sheet. Add 10 mg of the positive electrode on one side of the electrolyte sheet, apply a pressure of 4 t, and add a cerium-indium-lithium alloy sheet on the other side, apply a pressure of 1 t to obtain a lithium battery. Among them, the inner diameter of the circular mold is 10 mm, and the diameter of the cerium-indium-lithium alloy sheet is 10 mm.

[0061] Comparative Example 1

[0062] (1) The difference in the preparation method of the indium-lithium alloy material from that in Example 1 is as follows: Raw materials: indium sheet and metallic lithium sheet, with a molar ratio of 7:3. Repeatedly cold-press and mix the lithium sheet and the indium sheet to obtain an indium-lithium alloy.

[0063] (2) The difference in the preparation method of the lithium symmetric battery with an indium-lithium alloy material as the electrode from that in Example 1 is as follows:

[0064] Replace the cerium-indium-lithium alloy with an indium-lithium alloy.

[0065] (3) The difference in the preparation method of the lithium battery with an indium-lithium alloy material as the negative electrode from that in Example 1 is as follows:

[0066] Replace the cerium-indium-lithium alloy with an indium-lithium alloy.

[0067] Figure 1 is the charge-discharge curve of the lithium battery in Example 1 (negative electrode: cerium-indium-lithium alloy), Figure 2 is the charge-discharge curve of the lithium battery in Comparative Example 1 (negative electrode: indium-lithium alloy). Compared with Figure 2 the charge-discharge curve in Figure 1 has a larger capacity, smaller voltage polarization, and smaller capacity decay, indicating that the cerium-indium-lithium alloy negative electrode can achieve a more stable lithium insertion / extraction process.

[0068] Example 2

[0069] (1) The preparation method of the cerium-indium-lithium alloy material is different from that of Example 1 in that: in the raw materials, the cerium block is replaced by cerium powder, and the indium sheet is replaced by indium powder.

[0070] (2) For the lithium symmetric battery with the cerium-indium-lithium alloy material as the electrode, the specific preparation method is different from that of Example 1 in that: the electrolyte is a halide solid electrolyte (Li3YCl6).

[0071] (3) For the lithium battery with the cerium-indium-lithium alloy material as the negative electrode, the specific preparation method is different from that of Example 1 in that: the electrolyte is a halide solid electrolyte (Li3YCl6), and the positive electrode is a mixture of lithium manganate, Li3YCl6, and Ketjen black, with a mass ratio of 7:2:1.

[0072] Comparative Example 2

[0073] (1) The preparation method of the magnesium-indium-lithium alloy material is different from that of Example 2 in that: the raw materials are magnesium powder, indium sheet, and metallic lithium sheet, and their molar ratio is 0.07:0.65:0.28. The magnesium powder and the indium sheet are repeatedly cold-pressed into a mixed metal block.

[0074] (2) For the lithium symmetric battery with the magnesium-indium-lithium alloy material as the electrode, the preparation method is different from that of Example 2 in that: the cerium-indium-lithium alloy is replaced by the magnesium-indium-lithium alloy.

[0075] (3) For the lithium battery with the magnesium-indium-lithium alloy material as the negative electrode, the preparation method is different from that of Example 2 in that: the cerium-indium-lithium alloy is replaced by the magnesium-indium-lithium alloy.

[0076] Figure 3 is the charge-discharge curve of the lithium symmetric battery in Example 2 (negative electrode: cerium-indium-lithium alloy), Figure 4 is the charge-discharge curve of the lithium symmetric battery in Comparative Example 2 (negative electrode: magnesium-indium-lithium alloy). Compared with Figure 4 , Figure 3 the charge-discharge curve in

[0077] Example 3

[0078] (1) The preparation method of the lanthanum-tin-lithium alloy material is different from that of Example 1 in that: the raw materials are lanthanum block, tin sheet, and metallic lithium sheet, and their molar ratio is 1:11:8.

[0079] (2) The preparation method of the lithium symmetric battery with the lanthanum-tin-lithium alloy material as the electrode is different from that of Example 1 in that: the electrolyte is a sulfide solid electrolyte (Li7P3S 11 ), and its mass is 80 mg.

[0080] (3) The lithium battery with a lanthanum-tin-lithium alloy material as the negative electrode is different from that in Example 1 in the preparation method: the electrolyte is a sulfide solid electrolyte (Li7P3S 11 ), the positive electrode is a mixture of lithium cobaltate, Li7P3S 11 , and Ketjen black, and the mass ratio is 7:2.8:0.2.

[0081] Comparative Example 3

[0082] (1) The preparation method of the tin-lithium alloy material is different from that in Example 3: the raw materials are tin flakes and metal lithium flakes, and their molar ratio is 6:4. The lithium flakes and tin flakes are cold-pressed and mixed repeatedly to obtain the tin-lithium alloy.

[0083] (2) The preparation method of the lithium symmetric battery with the tin-lithium alloy material as the electrode is different from that in Example 1: the lanthanum-tin-lithium alloy is replaced with the tin-lithium alloy.

[0084] (3) The preparation method of the lithium battery with the tin-lithium alloy material as the negative electrode is different from that in Example 1: the lanthanum-tin-lithium alloy is replaced with the tin-lithium alloy.

[0085] Figure 5 is the SEM image of the lanthanum-tin-lithium alloy in Example 3, Figure 6 is the SEM image of the tin-lithium alloy in Comparative Example 3. Compared with the Figure 6 flat surface morphology, Figure 5 the SEM image in

[0086] Example 4

[0087] (1) The preparation method of the lanthanum-tin-lithium alloy material is different from that in Example 3: the raw materials are lanthanum powder, tin powder and metal lithium flakes. The lanthanum powder and tin powder are ground by hand into a mixed metal powder.

[0088] (2) The preparation method of the lithium symmetric battery with the lanthanum-tin-lithium alloy material as the electrode is different from that in Example 3: the electrolyte is a sulfide solid electrolyte (Li3PS4).

[0089] (3) The preparation method of the lithium battery with the lanthanum-tin-lithium alloy material as the negative electrode is different from that in Example 3: the electrolyte is a sulfide solid electrolyte (Li3PS4), and the positive electrode is a mixture of lithium cobaltate, Li3PS4, and Ketjen black, and the mass ratio is 7:2.8:0.2.

[0090] Comparative Example 4

[0091] (1) The preparation method of the zinc-tin-lithium alloy material is different from that of Example 4 in that the raw materials are zinc flakes, tin flakes and metallic lithium flakes. The zinc flakes and tin flakes are repeatedly cold-pressed into a mixed metal block.

[0092] (2) The preparation method of the lithium symmetric battery with the zinc-tin-lithium alloy material as the electrode is different from that of Example 1 in that the lanthanum-tin-lithium alloy is replaced by the zinc-tin-lithium alloy.

[0093] (3) The preparation method of the lithium battery with the zinc-tin-lithium alloy material as the negative electrode is different from that of Example 1 in that the lanthanum-tin-lithium alloy is replaced by the tin-lithium alloy.

[0094] Figure 7 is the electrochemical impedance spectrum of the lithium symmetric battery in Example 4 (negative electrode: lanthanum-tin-lithium alloy), Figure 8 is the electrochemical impedance spectrum of the lithium symmetric battery in Comparative Example 4 (negative electrode: zinc-tin-lithium alloy). Compared with Figure 8 that in Figure 7 , the electrochemical impedance spectrum shows a smaller interfacial impedance, indicating better compatibility between the lanthanum-tin-lithium alloy negative electrode and the electrolyte layer and more sufficient interfacial contact.

[0095] Example 5

[0096] (1) The preparation method of the yttrium-aluminum-lithium alloy material is as follows:

[0097] The raw materials are yttrium powder, aluminum powder and lithium powder. The yttrium powder, aluminum powder and lithium powder with a molar ratio of 0.10:0.45:0.45 are hand-ground for 10 min to obtain a mixed metal powder. Then, the mixed metal powder is placed in a ball milling tank and ball-milled for 5 h in an argon atmosphere at a ball milling speed of 400 r / min to obtain a yttrium-aluminum-lithium alloy powder.

[0098] (2) The preparation method of the lithium symmetric battery with the yttrium-aluminum-lithium alloy material as the electrode is as follows:

[0099] The electrolyte is a PEO-based polymer solid electrolyte membrane, and the electrode is a yttrium-aluminum-lithium alloy powder material.

[0100] The PEO-based polymer solid electrolyte membrane is cut into circular pieces with a thickness of 100 - 200 μm and a diameter of 12 mm; the yttrium-aluminum-lithium alloy powder is mixed with a binder, and the mass ratio of the binder is 0.5% - 5.0%. Then, a yttrium-aluminum-lithium alloy membrane is made by rolling or rolling, with a mass of 10 - 20 mg / cm 2, with a thickness of 100 - 200 μm. Cut the yttrium-aluminum-lithium alloy film into circular pieces with a diameter of 10 mm. Place the cut circular pieces into the CR2032 coin cell mold in the order of yttrium-aluminum-lithium alloy film, PEO-based polymer solid electrolyte film, and yttrium-aluminum-lithium alloy film, and encapsulate them with an encapsulation pressure of 0.5 t.

[0101] (3) The preparation method of a lithium battery with a yttrium-aluminum-lithium alloy material as the negative electrode is as follows:

[0102] The electrolyte is a PEO-based polymer solid electrolyte film, the negative electrode is a yttrium-aluminum-lithium alloy film, and the positive electrode is a composite of lithium manganate, carbon nanotubes, and a binder.

[0103] The preparation method of the positive electrode: Mix lithium manganate, carbon nanotubes, and a binder in a mass ratio of 8:1:1, and load the positive electrode onto the aluminum foil by smearing. The loading amount of the positive electrode is 5.0 - 10.0 mg / cm 2 . Cut the aluminum foil loaded with the positive electrode into circular pieces to obtain positive electrode sheets with a diameter of 10 mm.

[0104] Place the cut circular pieces into the CR2032 coin cell mold in the order of yttrium-aluminum-lithium alloy film, PEO-based polymer solid electrolyte film, and positive electrode sheet, and encapsulate them with an encapsulation pressure of 0.5 t.

[0105] Comparative Example 5

[0106] (1) The difference in the preparation method of the aluminum-lithium alloy material from that of Example 5 is that the raw materials are aluminum powder and lithium powder with a molar ratio of 1:1.

[0107] (2) The difference in the preparation method of a lithium symmetric battery with an aluminum-lithium alloy material as the electrode from that of Example 5 is that the yttrium-aluminum-lithium alloy is replaced with an aluminum-lithium alloy.

[0108] (3) The difference in the preparation method of a lithium battery with an aluminum-lithium alloy material as the negative electrode from that of Example 5 is that the yttrium-aluminum-lithium alloy is replaced with an aluminum-lithium alloy.

[0109] Figure 9 is the charge-discharge curve of the lithium battery in Example 5 (negative electrode: yttrium-aluminum-lithium alloy), Figure 10 is the charge-discharge curve of the lithium battery in Comparative Example 5 (negative electrode: aluminum-lithium alloy). Compared with Figure 10 , Figure 9 the charge-discharge curve in

[0110] Example 6

[0111] (1) The preparation method of the yttrium-aluminum-lithium alloy material is as follows:

[0112] The raw materials are yttrium powder, aluminum powder and lithium powder, and their molar ratio is 2:9:9. The yttrium powder, aluminum powder and lithium powder are manually ground evenly for 10 min. Then, the mixed metal powder is placed in a graphite crucible and calcined in an argon atmosphere at 700 °C for 5 h to obtain a yttrium-aluminum-lithium alloy block. After that, the yttrium-aluminum-lithium alloy block is placed in a ball milling tank and ball milled in an argon atmosphere for 5 h at a ball milling speed of 400 r / min to obtain yttrium-aluminum-lithium alloy powder.

[0113] (2) A lithium symmetric battery with a yttrium-aluminum-lithium alloy material as the electrode. The difference in the preparation method from Example 5 is that the electrolyte is a PAN-based polymer solid electrolyte membrane.

[0114] (3) A lithium battery with a yttrium-aluminum-lithium alloy material as the negative electrode. The difference in the preparation method from Example 5 is that the electrolyte is a PAN-based polymer solid electrolyte membrane.

[0115] Comparative Example 6

[0116] (1) The preparation method of the tin-aluminum-lithium alloy material is as follows:

[0117] The raw materials are tin powder, aluminum powder and lithium powder, and their molar ratio is 2:9:9. The tin powder, aluminum powder and lithium powder are manually ground evenly for 10 min. Then, the mixed metal powder is placed in a ball milling tank and ball milled in an argon atmosphere for 5 h at a ball milling speed of 400 r / min to obtain tin-aluminum-lithium alloy powder.

[0118] (2) A lithium symmetric battery with a tin-aluminum-lithium alloy material as the electrode. The difference in the preparation method from Example 6 is that the yttrium-aluminum-lithium alloy is replaced by the tin-aluminum-lithium alloy.

[0119] (3) A lithium battery with a tin-aluminum-lithium alloy material as the negative electrode. The difference in the preparation method from Example 6 is that the yttrium-aluminum-lithium alloy is replaced by the tin-aluminum-lithium alloy.

[0120] Figure 11 is the electrochemical impedance spectrum of the lithium symmetric battery in Example 6 (negative electrode: yttrium-aluminum-lithium alloy), Figure 12 is the electrochemical impedance spectrum of the lithium symmetric battery in Comparative Example 6 (negative electrode: tin-aluminum-lithium alloy). Compared with Figure 12 the Figure 11 electrochemical impedance spectrum shows a smaller interfacial impedance, indicating better compatibility between the yttrium-aluminum-lithium alloy negative electrode and the electrolyte layer and more sufficient interfacial contact.

[0121] Example 7

[0122] (1) The praseodymium-silicon-lithium alloy material, the preparation method is as follows:

[0123] The raw materials are praseodymium powder, silicon powder and lithium flakes, and their molar ratio is 1:11:8. The praseodymium powder and silicon powder are manually ground evenly for 10 min. Then, the mixed metal powder is placed in a crucible and calcined at a high temperature in an argon atmosphere. The calcination temperature is 1000 °C and the calcination time is 1 h, and praseodymium-silicon alloy powder can be obtained. Then, the lithium flakes are mixed with the praseodymium-silicon alloy powder and manually ground for 20 min to obtain praseodymium-silicon-lithium alloy powder.

[0124] (2) The lithium symmetric battery with the praseodymium-silicon-lithium alloy material as the electrode is prepared as follows:

[0125] The electrolyte is a solid oxide electrolyte (LLZO) wafer; the electrode is a praseodymium-silicon-lithium alloy powder material.

[0126] The thickness of the LLZO wafer is 200 - 400 μm and the diameter is 12 mm; the praseodymium-silicon-lithium alloy powder is mixed with a binder, and the mass ratio of the binder is 0.5% - 5.0%. Then, a praseodymium-silicon-lithium alloy film with a mass of 10 - 20 mg / cm 2 and a thickness of 100 - 200 μm is made by rolling or rolling. The praseodymium-silicon-lithium alloy film is cut into wafers with a diameter of 10 mm. The cut wafers are sequentially placed in a CR2032 coin cell mold in the order of praseodymium-silicon-lithium alloy film, LLZO wafer, and praseodymium-silicon-lithium alloy film. Among them, a carbonate-based electrolyte with a volume of 100 - 200 μL needs to be dropped between the praseodymium-silicon-lithium alloy film and the LLZO wafer, and then encapsulated with an encapsulation pressure of 0.5 t.

[0127] (3) The lithium battery with the praseodymium-silicon-lithium alloy material as the negative electrode is prepared as follows:

[0128] The electrolyte is an LLZO wafer; the negative electrode is a praseodymium-silicon-lithium alloy film; the positive electrode is a composite of nickel-cobalt-manganese ternary material, Ketjen black, and binder.

[0129] The preparation method of the positive electrode: Mix the nickel-cobalt-manganese ternary material, Ketjen black, and binder with a mass ratio of 8:1:1, and load the positive electrode on the aluminum foil by smearing. The loading amount of the positive electrode is 5.0 - 10.0 mg / cm 2 . The aluminum foil loaded with the positive electrode is cut into wafers to obtain positive electrode sheets with a diameter of 10 mm.

[0130] The cut wafers are sequentially placed in a CR2032 coin cell mold in the order of praseodymium-silicon-lithium alloy film, LLZO wafer, and positive electrode sheet. Among them, a carbonate-based electrolyte with a volume of 100 - 200 μL needs to be dropped between the praseodymium-silicon-lithium alloy film and the LLZO wafer and between the positive electrode sheet and the LLZO wafer, and then encapsulated with an encapsulation pressure of 0.5 t.

[0131] Comparative Example 7

[0132] (1) The silicon-lithium alloy material was prepared as follows:

[0133] The raw materials were silicon powder and lithium flakes, and their molar ratio was 1:1. The lithium flakes and silicon powder were mixed and ground by hand for 20 min to obtain silicon-lithium alloy powder.

[0134] (2) The lithium symmetric battery with the silicon-lithium alloy material as the electrode was prepared in the same way as in Example 7, except that the praseodymium-silicon-lithium alloy was replaced by the silicon-lithium alloy.

[0135] (3) The lithium battery with the praseodymium-silicon-lithium alloy material as the negative electrode was prepared in the same way as in Example 7, except that the praseodymium-silicon-lithium alloy was replaced by the silicon-lithium alloy.

[0136] Figure 13 is the electrochemical impedance spectrum after cycling of the lithium symmetric battery in Example 7 (negative electrode: praseodymium-silicon-lithium alloy), Figure 14 is the electrochemical impedance spectrum after cycling of the lithium symmetric battery in Comparative Example 7 (negative electrode: silicon-lithium alloy). Compared with Figure 14 the Figure 13 electrochemical impedance spectrum shows a smaller interfacial impedance, indicating that a better interfacial contact can be maintained between the praseodymium-silicon-lithium alloy negative electrode and the electrolyte layer after battery cycling.

[0137] Example 8

[0138] (1) The preparation method of the praseodymium-silicon-lithium alloy material was different from that in Example 7 in that the calcination temperature of the mixed metal powder was 900 °C, the calcination time was 5 h, the lithium powder was mixed with the praseodymium-silicon alloy powder, the ball milling speed was 400 r / min, and the ball milling time was 2 h.

[0139] (2) The lithium symmetric battery with the praseodymium-silicon-lithium alloy material as the electrode was prepared in the same way as in Example 7, except that the electrolyte was a disk of oxide solid electrolyte (LATP).

[0140] (3) The lithium battery with the praseodymium-silicon-lithium alloy material as the negative electrode was prepared in the same way as in Example 7, except that the electrolyte was a disk of oxide solid electrolyte (LATP).

[0141] Comparative Example 8

[0142] (1) The preparation method of the magnesium-silicon-lithium alloy material was different from that in Example 8 in that the raw materials were magnesium powder, silicon powder and lithium powder.

[0143] (2) The lithium symmetric battery with the magnesium-silicon-lithium alloy material as the electrode was prepared in the same way as in Example 8, except that the praseodymium-silicon-lithium alloy was replaced by the magnesium-silicon-lithium alloy.

[0144] (3) The lithium battery with a magnesium-silicon-lithium alloy material as the negative electrode is different from that in Example 8 in the preparation method: the praseodymium-silicon-lithium alloy is replaced by the magnesium-silicon-lithium alloy.

[0145] Figure 15 is the charge-discharge curve of the lithium battery in Example 8 (negative electrode: praseodymium-silicon-lithium alloy), Figure 16 is the charge-discharge curve of the lithium battery in Comparative Example 8 (negative electrode: magnesium-silicon-lithium alloy). Compared with Figure 16 compared, Figure 15 the charge-discharge curve in has more stable performance, and the capacity attenuation is not obvious, indicating that the praseodymium-silicon-lithium alloy negative electrode can maintain more sufficient and stable lithium ion diffusion during charge and discharge.

[0146] Example 9

[0147] (1) The preparation method of the yttrium-silicon-graphite-lithium alloy material is as follows:

[0148] The raw materials are yttrium powder, silicon powder, graphite powder and lithium powder, and their molar ratio is 1:5:9:5. The yttrium powder, silicon powder, graphite powder and lithium powder are manually ground evenly for 10 min, and then the mixed metal powder is placed in a ball milling tank and ball milled for 5 h in an argon atmosphere at a ball milling speed of 400 r / min to obtain the yttrium-silicon-graphite-lithium alloy powder.

[0149] (2) The preparation method of the lithium symmetric battery with the yttrium-silicon-graphite-lithium alloy material as the electrode is as follows:

[0150] The electrolyte is an ether-based electrolyte; the electrode is the yttrium-silicon-graphite-lithium alloy powder material.

[0151] The glass fiber separator is cut into a round piece with a diameter of 16 mm, and then infiltrated with the ether-based electrolyte, and the volume of the electrolyte is 200 - 400 μL to obtain the electrolyte / separator sheet. The yttrium-silicon-graphite-lithium alloy powder is mixed with the binder, and the mass ratio of the binder is 0.5% - 5.0%, and then it is made into a yttrium-silicon-graphite-lithium alloy film by rolling or rolling, with a mass of 10 - 20 mg / cm 2 and a thickness of 100 - 200 μm. The yttrium-silicon-graphite-lithium alloy film is cut into a round piece with a diameter of 10 mm. The cut round pieces are sequentially placed into a CR2032 button battery mold in the order of the yttrium-silicon-graphite-lithium alloy film, the electrolyte / separator, and the yttrium-silicon-graphite-lithium alloy film, and encapsulated, and the encapsulation pressure is 0.5 t.

[0152] (3) The preparation method of the lithium battery with the yttrium-silicon-graphite-lithium alloy material as the negative electrode is as follows:

[0153] The electrolyte is an ether-based electrolyte; the negative electrode is a yttrium-silicon-graphite-lithium alloy film; the positive electrode is a composite of selenium disulfide, acetylene black, and a binder.

[0154] Preparation method of the positive electrode: Selenium disulfide, Ketjen black, and a binder with a mass ratio of 7:2:1 are mixed, and the positive electrode is loaded on an aluminum foil by a coating method, and the loading amount of the positive electrode is 5.0 - 10.0 mg / cm 2 . The aluminum foil loaded with the positive electrode is cut into circular pieces to obtain positive electrode sheets with a diameter of 10 mm.

[0155] The cut circular pieces are sequentially placed into a CR2032 coin cell mold in the order of yttrium-silicon-graphite-lithium alloy film, electrolyte / separator, and positive electrode sheet, and then encapsulated, and the encapsulation pressure is 0.5 t.

[0156] Comparative Example 9

[0157] (1) The difference in the preparation method of the silicon-graphite-lithium alloy material from that of Example 9 is that the raw materials are silicon powder, graphite powder, and lithium powder, and their molar ratio is 1:2:1.

[0158] (2) For the lithium symmetric battery with the silicon-graphite-lithium alloy material as the electrode, the difference in the preparation method from that of Example 9 is that the yttrium-silicon-graphite-lithium alloy is replaced with the silicon-graphite-lithium alloy.

[0159] (3) For the lithium battery with the silicon-graphite-lithium alloy material as the negative electrode, the difference in the preparation method from that of Example 9 is that the yttrium-silicon-graphite-lithium alloy is replaced with the silicon-graphite-lithium alloy.

[0160] Figure 17 is the cycle performance of the lithium battery in Example 9 (negative electrode: yttrium-silicon-graphite-lithium alloy), Figure 18 is the cycle performance of the lithium battery in Comparative Example 9 (negative electrode: silicon-graphite-lithium alloy). Compared with Figure 18 that, Figure 17 the cycle performance of the battery in

[0161] Example 10

[0162] (1) The preparation method of the yttrium-silicon-graphite-lithium alloy material is as follows:

[0163] The raw materials are yttrium powder, silicon powder, graphite powder, and lithium powder, and their molar ratio is 1:4:9:6. The yttrium powder, silicon powder, graphite powder, and lithium powder are manually ground evenly for 20 min, and then the mixed metal powder is placed in a ball mill jar and ball milled for 10 h in an argon atmosphere at a ball mill speed of 300 r / min to obtain yttrium-silicon-graphite-lithium alloy powder.

[0164] (2) The lithium symmetric battery with a yttrium-silicon-graphite-lithium alloy material as the electrode, the difference in the preparation method from Example 9 lies in that: the electrolyte is a carbonate-based electrolyte solution.

[0165] (3) The lithium battery with a yttrium-silicon-graphite-lithium alloy material as the negative electrode, the difference in the preparation method from Example 9 lies in that: the electrolyte is a carbonate-based electrolyte solution.

[0166] Comparative Example 10

[0167] (1) The difference in the preparation method of the tin-silicon-graphite-lithium alloy material from Example 9 lies in that: the raw materials are tin powder, silicon powder, graphite powder and lithium powder.

[0168] (2) The lithium symmetric battery with a tin-silicon-graphite-lithium alloy material as the electrode, the difference in the preparation method from Example 9 lies in that: the yttrium-silicon-graphite-lithium alloy is replaced by the tin-silicon-graphite-lithium alloy.

[0169] (3) The lithium battery with a tin-silicon-graphite-lithium alloy material as the negative electrode, the difference in the preparation method from Example 9 lies in that: the yttrium-silicon-graphite-lithium alloy is replaced by the tin-silicon-graphite-lithium alloy.

[0170] Figure 19 is the charge-discharge curve of the lithium battery in Example 10 (negative electrode: yttrium-silicon-graphite-lithium alloy), Figure 20 is the charge-discharge curve of the lithium battery in Comparative Example 10 (negative electrode: tin-silicon-graphite-lithium alloy). Compared with Figure 20 the Figure 19 charge-discharge curve in

[0171] has a larger capacity and the attenuation is not obvious, indicating that the yttrium-silicon-graphite-lithium alloy negative electrode can maintain a more sufficient and stable lithium ion diffusion during the charge-discharge process.

[0172] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A preparation method of a rare earth-based lithium alloy negative electrode material, characterized in that, It includes the following steps: S1: Mechanically mix rare earths and active materials to obtain a rare earth-active material mixture; S2: Calcinate the rare earth-active material mixture obtained in step S1 at 500-1500 °C for 1-10 h to obtain a rare earth-based alloy material; S3: Mechanically mix lithium metal and the rare earth-based alloy material obtained in step S2 to obtain a rare earth-based lithium alloy material; Wherein, the molar ratio of the rare earths, active materials, and lithium metal is 1-50:1-99:1-99.

2. The preparation method of a rare earth-based lithium alloy negative electrode material according to claim 1, characterized in that, The rare earths include one or more of scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium.

3. The preparation method of a rare earth-based lithium alloy anode material according to claim 1, characterized in that, The lithium metal is one or more of lithium blocks, lithium sheets, and lithium powders.

4. The preparation method of a rare earth-based lithium alloy negative electrode material as described in claim 1, characterized in that, The active materials include alloy-type negative electrodes indium, tin, aluminum, magnesium, silicon, germanium, antimony, bismuth, and one or more of carbon-based negative electrodes graphite, graphene, hard carbon, and soft carbon. A rare earth-based lithium alloy negative electrode material prepared by the method according to any one of claims 1-4. An application of the rare earth-based lithium alloy negative electrode material according to claim 5 in a lithium battery.

7. The application of a rare earth-based lithium alloy negative electrode material in a lithium battery as described in claim 6, wherein, It includes a negative electrode, an electrolyte, and a positive electrode, and the negative electrode is a rare earth-based lithium alloy negative electrode material.

8. The application of a rare earth-based lithium alloy negative electrode material in a lithium battery as claimed in claim 7, wherein, The electrolyte includes one or two of a liquid electrolyte and a solid electrolyte. The liquid electrolyte includes one or two of a carbonate-based electrolyte and an ether-based electrolyte. The solid electrolyte includes one or more of a polymer electrolyte, an oxide electrolyte, a sulfide electrolyte, and a halide electrolyte.

9. The application of a rare earth-based lithium alloy negative electrode material in a lithium battery as claimed in claim 7, characterized in that, The positive electrode includes 10%-90% of positive electrode active materials, 0-70% of solid electrolyte, 0-20% of carbon materials, and 0-10% of binder. The positive electrode active materials include one or more combinations of lithium-containing positive electrodes or lithium-free positive electrodes. The carbon materials include one or more combinations of acetylene black, Ketjen black, carbon nanotubes, graphite, graphene, soft carbon, hard carbon, activated carbon, and carbon fiber.

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