Preparation Method of Aerogel Current Collector and Preparation Method of Composite Anode

Abstract

The present invention discloses a preparation method of an aerogel current collector and a preparation method of a composite negative electrode, belonging to the technical field of energy storage batteries. The preparation method of the aerogel current collector includes: Step 1, stirring and mixing metal nanowires, a flocculant, and water in a mass ratio of n:1:m to obtain a hydrogel, where 1≤n≤10 and 1≤m≤10; Step 2, placing the hydrogel in a mold and freezing it for a certain time through liquid nitrogen and / or a refrigerator and / or a cold trap to obtain a solid gel; Step 3, putting the solid gel into a freeze dryer and drying it for 24-72 h to obtain an aerogel, and obtaining an ultra-light metal nanowire aerogel current collector after demolding. The ultra-light metal nanowire aerogel current collector proposed by the present invention has an ultra-high porosity (99%) and excellent mechanical properties, and the preparation process is simple, environmentally friendly, low in danger, and low in cost, and the ultra-light metal nanowire aerogel current collector can accommodate an ultra-high amount of metallic lithium loading.

Description

Technical Field

[0001] The present invention relates to a preparation method of an aerogel current collector and a preparation method of a composite negative electrode, belonging to the technical field of energy storage batteries. Background Art

[0002] Benefiting from the rapid development of lithium-ion batteries, portable electronic devices, electric bicycles and electric vehicles have gradually penetrated into people's lives. In the case of electric vehicles, the energy density of power batteries determines the cruising range of electric vehicles. Taking the currently widely used lithium-ion batteries as an example, graphite is used for the negative electrode (the theoretical specific capacity is 372 mAh g -1 ), and layered electrodes, spinel electrodes and olivine are used for the positive electrode. The energy density of the full battery has approached its theoretical limit, but it is still difficult to meet the requirements of high energy density. Metallic lithium has a high theoretical specific capacity (3860 mAh g -1 ) and a low redox potential (relative to the standard hydrogen electrode -3.040 V), so it is regarded as the most potential material. However, rechargeable batteries with metallic lithium have not yet been commercially produced. The two main scientific problems are the safety and recyclability of lithium metal batteries.

[0003] In order to solve the problems targeted, designing the current collector into a three-dimensional porous structure can effectively increase the loading of active substances and at the same time improve its conductivity. Therefore, the development of lightweight, highly conductive and highly porous three-dimensional porous current collectors is crucial for the application of lithium metal negative electrodes. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method of an aerogel current collector and a preparation method of a composite negative electrode, so as to reduce the potential safety hazards of the battery, increase the battery life and stability, improve the energy density of lithium metal batteries, not only simplify the production operation of lithium metal batteries, but also reduce pollution, energy consumption and costs.

[0005] To achieve the above purpose, the present invention provides a preparation method of an aerogel current collector, including:

[0006] Step 1, stirring and mixing metal nanowires, a flocculant and water in a mass ratio of n:1:m to obtain a hydrogel, where 1 ≤ n ≤ 10 and 1 ≤ m ≤ 10;

[0007] Step 2, placing the hydrogel in a mold and freezing it for a certain time through liquid nitrogen and / or a refrigerator and / or a cold trap to obtain a solid gel;

[0008] Step 3, putting the solid gel into a freeze dryer and drying it for 24 - 72 h to obtain an aerogel, and obtaining an ultra-light metal nanowire aerogel current collector after demolding.

[0009] As a further improvement of the present invention, the metal nanowires in step 1 are one or a combination of several of copper nanowires, silver nanowires, gold nanowires, copper-nickel alloy nanowires, nickel nanowires, and copper-silver alloy nanowires.

[0010] As a further improvement of the present invention, the flocculant in step 1 is one or a combination of several of polyvinylpyrrolidone, hydroxypropyl cellulose, lignin fiber, hydroxyethyl cellulose, and carboxymethyl cellulose.

[0011] As a further improvement of the present invention, the water in step 1 is deionized water.

[0012] As a further improvement of the present invention, the ratio of the metal nanowires, flocculant, and water in step 1 is 3:1:3.

[0013] As a further improvement of the present invention, the freezing time in step 2 is 1 h, and the material of the mold is polytetrafluoroethylene.

[0014] As a further improvement of the present invention, the drying time in step 3 is 48 h.

[0015] To achieve the above object, the present invention also provides a method for preparing a composite negative electrode. Using the ultra-light metal nanowire aerogel current collector prepared by the aforementioned method for preparing an aerogel current collector as the positive electrode, and a lithium foil as the negative electrode, deposition is carried out at a current density of 1 mA cm -2 and a lithium deposition amount of 1 - 10 mAh cm -2 to obtain a composite negative electrode.

[0016] To achieve the above object, the present invention also provides a method for preparing a composite negative electrode. Molten metallic lithium is melted under an inert gas, and the ultra-light metal nanowire aerogel current collector prepared by the aforementioned method for preparing an aerogel current collector is placed on the molten liquid metallic lithium, and pressure is applied to cause the liquid metallic lithium to be inhaled into the grid structure of the ultra-light metal nanowire aerogel current collector to obtain a composite negative electrode.

[0017] As a further improvement of the present invention, the inert gas is argon, and the temperature of the molten metallic lithium is 400 °C.

[0018] The beneficial effects of the present invention are as follows: The production method of the aerogel current collector of the present invention can prepare a three-dimensional metal nanowire aerogel current collector, which can increase the specific surface area of the current collector, enhance the mechanical properties of the current collector, relieve the volume expansion caused by lithium deposition / dissolution, reduce the current density, not only reduce the internal contact resistance between copper and lithium, but also effectively inhibit the formation of dendritic lithium, prevent safety problems such as short circuits caused during the cycling of the battery, greatly improve the safety, stability and lifespan of the battery, and the metal nanowire aerogel is light in weight, can accommodate more lithium, reduce the mass of inactive substances, improve the energy density of the battery, and at the same time can simplify the production operation, reduce pollution, energy consumption and cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is the preparation flow chart of the ultra-light metal nanowire current collector of the present invention.

[0020] Figure 2 is the morphology photograph of the ultra-light metal nanowire current collector of the present invention.

[0021] Figure 3 is the electrochemical performance of the half-cell of the ultra-light metal nanowire current collector of the present invention.

[0022] Figure 4 is the performance graph of the symmetric cell of the composite negative electrode of the ultra-light metal nanowire current collector of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] As Figure 1 shown, the present invention discloses a production method of a metal nanowire aerogel current collector to reduce the potential safety hazards of the battery, increase the lifespan and stability of the battery, improve the energy density of the lithium metal battery, not only simplify the production operation of the lithium metal battery, but also reduce pollution, energy consumption and cost.

[0025] The main steps include:

[0026] Step 1: Stir and mix the metal nanowire 1, the flocculant 2, and the water 3 in a mass ratio of n:1:m to obtain a hydrogel A, where 1 ≤ n ≤ 10 and 1 ≤ m ≤ 10.

[0027] Step 2: Place the hydrogel A in a mold and freeze it for a certain period of time through liquid nitrogen and / or a refrigerator and / or a cold trap to obtain a solid gel B, and a large number of ice crystals in a certain shape are included in the solid gel B. Preferably, the material of the mold is polytetrafluoroethylene, and the freezing time is 1 h.

[0028] Step 3: Place the solid gel B into a freeze dryer and dry it for 24 - 72 h to obtain the aerogel C. The aerogel C contains a large number of pores formed by air that are similar in shape to the aforementioned ice crystals. After demolding, a super-light metal nanowire aerogel current collector is obtained. Preferably, the drying time is 48 h.

[0029] Preferably, in Step 1, the ratio of the metal nanowires 1, the flocculant 2, and the water 3 is 3:1:3. The water 3 in Step 1 is deionized water 3. Of course, in other embodiments, the water 3 in Step 1 can also be one of pure water, high-purity water, and ultra-pure water, and there is no limitation here.

[0030] Specifically, the metal nanowires 1 in Step 1 are one or a combination of copper nanowires, silver nanowires, gold nanowires, copper-nickel alloy nanowires, nickel nanowires, and copper-silver alloy nanowires. Of course, in other embodiments, they can also be nanowires of other metals or alloys, and there is no limitation here.

[0031] The flocculant 2 in Step 1 is one or a combination of polyvinylpyrrolidone, hydroxypropyl cellulose, lignin fiber, hydroxyethyl cellulose, and carboxymethyl cellulose. Of course, in other embodiments, it can also be other flocculants 2 with the same function, and there is no limitation here.

[0032] The present invention also provides a method for preparing a composite negative electrode, specifically a constant current electrochemical deposition method. Using the super-light metal nanowire aerogel current collector prepared by the aforementioned method for preparing the aerogel current collector as the positive electrode and a lithium foil as the negative electrode, deposit at a current density of 1 mA cm -2 and a lithium deposition amount of 1 - 10 mAh cm -2 to prepare the composite negative electrode.

[0033] The present invention also provides another method for preparing a composite negative electrode, specifically a hot melt perfusion method. Under the protection of an inert gas, melt metallic lithium, place the super-light metal nanowire aerogel current collector prepared by the aforementioned method for preparing the aerogel current collector on the molten liquid metallic lithium, and apply pressure to make the liquid metallic lithium be inhaled into the grid structure of the super-light metal nanowire aerogel current collector to obtain the composite negative electrode. Preferably, the inert gas is argon, and the temperature of the molten metallic lithium is 400 °C.

[0034] The present invention also provides specific embodiments for preparing the super-light metal nanowire aerogel current collector and the composite negative electrode, which are specifically as follows:

[0035] Example 1

[0036] Take 1 kg of copper nanowires, hydroxypropyl cellulose, and ultrapure water, stir and mix them evenly at a mass ratio of 5:1:5, place them in a polytetrafluoroethylene mold, and freeze them with liquid nitrogen; freeze for 1 h to obtain solid gel B, and place solid gel B in a freeze dryer and dry for 48 h; after drying is completed, remove the mold to obtain an ultra-light three-dimensional porous copper nanowire current collector.

[0037] Select the battery model as a 2032-type button battery. Therefore, the diameter of the electrode sheet is set to 12 mm. Assemble a button battery with the copper nanowire current collector as the positive electrode and lithium foil as the negative electrode. At the same time, at a current density of 1 mA cm -2 and a lithium deposition amount of 1 mAh cm -2 deposit to prepare a composite negative electrode of copper nanowire aerogel composite lithium metal. Of course, in other embodiments, other battery models can also be selected, which are not limited here.

[0038] Assemble the composite negative electrode of copper nanowire aerogel composite lithium metal in a symmetric battery, test the voltage hysteresis under a small current, and the test value is 22 mV, proving that the copper nanowire aerogel current collector has very good stability.

[0039] Example 2

[0040] Take 1 kg of silver nanowires, hydroxypropyl cellulose, and ultrapure water, stir and mix them evenly at a mass ratio of 5:1:5, place them in a polytetrafluoroethylene mold, and freeze them with liquid nitrogen; freeze for 1 h to obtain solid gel B, and place solid gel B in a freeze dryer and dry for 48 h; after drying is completed, remove the mold to obtain an ultra-light three-dimensional porous silver nanowire current collector.

[0041] Select the battery model as a 2032-type button battery. Therefore, the diameter of the electrode sheet is set to 12 mm. Assemble a button battery with the silver nanowire current collector as the positive electrode and lithium foil as the negative electrode. At the same time, at a current density of 1 mA cm -2 and a lithium deposition amount of 1 mAh cm -2 deposit to prepare a composite negative electrode of silver nanowire aerogel composite lithium metal. Of course, in other embodiments, other battery models can also be selected, which are not limited here.

[0042] Assemble the composite negative electrode of silver nanowire aerogel composite lithium metal in a symmetric battery, test the voltage hysteresis under a small current, and the test value is 25 mV, proving that this silver nanowire aerogel current collector has very good stability.

[0043] Example 3

[0044] Take 1 kg of copper nanowires, polyvinylpyrrolidone, and ultrapure water, and stir and mix them evenly at a mass ratio of 5:1:5. Place them in a polytetrafluoroethylene mold and freeze them with liquid nitrogen; freeze for 1 h to obtain solid gel B, and place solid gel B in a freeze dryer and dry for 24 h; after drying is completed, remove the mold to obtain an ultra-light three-dimensional porous copper nanowire current collector.

[0045] Select the battery model as a 2032-type button battery. Therefore, the diameter of the electrode sheet is set to 12 mm. Assemble a button battery with the copper nanowire current collector as the positive electrode and lithium foil as the negative electrode. At the same time, at a current density of 1 mA cm -2 and a lithium deposition amount of 1 mAh cm -2 deposit to prepare a composite negative electrode of copper nanowire aerogel composite lithium metal. Of course, in other embodiments, other battery models can also be selected, and there is no limitation here.

[0046] Assemble the composite negative electrode of copper nanowire aerogel composite lithium metal in a symmetric battery, and test its voltage hysteresis under a small current. The test value is 28 mV, which proves that the stability of this copper nanowire aerogel current collector is very good.

[0047] Example 4

[0048] Take 1 kg of copper nanowires, lignin fibers, and ultrapure water, and stir and mix them evenly at a mass ratio of 1:1:1. Place them in a polytetrafluoroethylene mold and freeze them with liquid nitrogen; freeze for 1 h to obtain solid gel B, and place solid gel B in a freeze dryer and dry for 48 h; after drying is completed, remove the mold to obtain an ultra-light three-dimensional porous copper nanowire current collector.

[0049] Select the battery model as a 2032-type button battery. Therefore, the diameter of the electrode sheet is set to 12 mm. Assemble a button battery with the copper nanowire current collector as the positive electrode and lithium foil as the negative electrode. At the same time, at a current density of 1 mA cm -2 and a lithium deposition amount of 1 mAh cm -2 deposit to prepare a composite negative electrode of copper nanowire aerogel composite lithium metal. Of course, in other embodiments, other battery models can also be selected, and there is no limitation here.

[0050] Assemble the composite negative electrode of copper nanowire aerogel composite lithium metal in a symmetric battery, and test its voltage hysteresis under a small current. The test value is 23 mV, which proves that the stability of this copper nanowire aerogel current collector is very good.

[0051] Example 5

[0052] Take 1 kg of copper nanowires, hydroxyethyl cellulose, and ultrapure water, stir and mix them evenly at a mass ratio of 10:1:10, place them in a polytetrafluoroethylene mold, and freeze them with liquid nitrogen; freeze for 1 h to obtain solid gel B, and put solid gel B into a freeze dryer and dry for 48 h; after drying, remove the mold to obtain an ultra-light three-dimensional porous copper nanowire current collector.

[0053] Select the battery model as a 2032-type button battery. Therefore, the diameter of the electrode sheet is set to 12 mm. Assemble a button battery with the copper nanowire current collector as the positive electrode and lithium foil as the negative electrode. At the same time, at a current density of 1 mA cm -2 , deposit to prepare a composite negative electrode of copper nanowire aerogel composite lithium metal with a lithium deposition amount of 1 mAh cm -2 . Of course, in other embodiments, other battery models can also be selected, which are not limited here.

[0054] Assemble the composite negative electrode of copper nanowire aerogel composite lithium metal in a symmetric battery, test its voltage hysteresis under a small current, and the test value is 28 mV, proving that the stability of this copper nanowire aerogel current collector is very good.

[0055] Example 6

[0056] Take 1 kg of copper nanowires, carboxymethyl cellulose, and ultrapure water, stir and mix them evenly at a mass ratio of 5:1:5, place them in a polytetrafluoroethylene mold, and freeze them with liquid nitrogen; freeze for 1 h to obtain solid gel B, and put solid gel B into a freeze dryer and dry for 24 h; after drying, remove the mold to obtain an ultra-light three-dimensional porous copper nanowire current collector.

[0057] Select the battery model as a 2032-type button battery. Therefore, the diameter of the electrode sheet is set to 12 mm. Assemble a button battery with the copper nanowire current collector as the positive electrode and lithium foil as the negative electrode. At the same time, at a current density of 1 mA cm -2 , deposit to prepare a composite negative electrode of copper nanowire aerogel composite lithium metal with a lithium deposition amount of 1 mAh cm -2 . Of course, in other embodiments, other battery models can also be selected, which are not limited here.

[0058] Assemble the composite negative electrode of copper nanowire aerogel composite lithium metal in a symmetric battery, test its voltage hysteresis under a small current, and the test value is 27 mV, proving that the stability of this copper nanowire aerogel current collector is very good.

[0059] Example 7

[0060] Take 1 kg of gold nanowires, hydroxypropyl cellulose, and ultrapure water, stir and mix them evenly at a mass ratio of 5:1:5, place them in a polytetrafluoroethylene mold, and freeze them with liquid nitrogen; freeze for 1 h to obtain a solid gel B, and place the solid gel B in a freeze dryer and dry for 48 h; after drying is completed, remove the mold to obtain an ultra-light three-dimensional porous gold nanowire current collector.

[0061] Place the current collector on the molten liquid metal lithium, apply pressure to make the liquid metal lithium inhale into the grid structure of the ultra-light metal nanowire aerogel current collector to obtain a composite negative electrode. Select the battery model as a 2032-type button battery, assemble the composite negative electrode of the gold nanowire aerogel composite lithium metal in a symmetric battery, and test its voltage hysteresis under a small current. The test value is 19 mV, which proves that this gold nanowire aerogel current collector has very good stability.

[0062] Example 8

[0063] Take 1 kg of copper-nickel nanowires, hydroxypropyl cellulose, and ultrapure water, stir and mix them evenly at a mass ratio of 5:1:5, place them in a polytetrafluoroethylene mold, and freeze them with liquid nitrogen; freeze for 1 h to obtain a solid gel B, and place the solid gel B in a freeze dryer and dry for 48 h; after drying is completed, remove the mold to obtain an ultra-light three-dimensional porous copper-nickel nanowire current collector.

[0064] Select the battery model as a 2032-type button battery. Therefore, the diameter of the electrode sheet is set to 12 mm. Use the copper-nickel nanowire current collector as the positive electrode and the lithium foil as the negative electrode to assemble a button battery. At the same time, at a current density of 1 mA cm -2 and a lithium deposition amount of 1 mAh cm -2 , deposit to prepare a composite negative electrode of copper-nickel nanowire aerogel composite lithium metal. Of course, in other embodiments, other battery models can also be selected, which are not limited here.

[0065] Assemble the composite negative electrode of copper-nickel nanowire aerogel composite lithium metal in a symmetric battery, and test its voltage hysteresis under a small current. The test value is 26 mV, which proves that this copper-nickel nanowire aerogel current collector has very good stability.

[0066] Example 9

[0067] Take 1 kg of nickel nanowires, hydroxypropyl cellulose, and ultrapure water, stir and mix them evenly at a mass ratio of 5:1:5, place them in a polytetrafluoroethylene mold, and freeze them with liquid nitrogen; freeze for 1 h to obtain a solid gel B, and place the solid gel B in a freeze dryer and dry for 72 h; after drying is completed, remove the mold to obtain an ultra-light three-dimensional porous nickel nanowire current collector.

[0068] The selected battery model is the 2032 button battery. Therefore, the diameter of the electrode sheet is set to 12 mm. A nickel nanowire current collector is used as the positive electrode, and a lithium foil is used as the negative electrode to assemble a button battery. At the same time, with a current density of 1 mA cm -2 and a lithium deposition amount of 1 mAh cm -2 , a composite negative electrode of nickel nanowire aerogel composite lithium metal is deposited and prepared. Of course, in other embodiments, other battery models can also be selected, which are not limited here.

[0069] The composite negative electrode of nickel nanowire aerogel composite lithium metal is assembled in a symmetric battery, and its voltage hysteresis under a small current is tested. The test value is 32 mV, which proves that the stability of this nickel nanowire aerogel current collector is very good.

[0070] Example 10

[0071] Take 1 kg of copper-silver nanowires, hydroxypropyl cellulose, and ultrapure water, stir and mix them evenly in a mass ratio of 5:1:5, place them in a polytetrafluoroethylene mold, and freeze them with liquid nitrogen; freeze for 1 h to obtain solid gel B, and put solid gel B into a freeze dryer and dry for 48 h; after drying, remove the mold to obtain an ultra-light three-dimensional porous copper-silver nanowire current collector.

[0072] The selected battery model is the 2032 button battery. Therefore, the diameter of the electrode sheet is set to 12 mm. A copper-silver nanowire current collector is used as the positive electrode, and a lithium foil is used as the negative electrode to assemble a button battery. At the same time, with a current density of 1 mA cm -2 and a lithium deposition amount of 1 mAh cm -2 , a composite negative electrode of copper-silver nanowire aerogel composite lithium metal is deposited and prepared. Of course, in other embodiments, other battery models can also be selected, which are not limited here.

[0073] The composite negative electrode of copper-silver nanowire aerogel composite lithium metal is assembled in a symmetric battery, and its voltage hysteresis under a small current is tested. The test value is 21 mV, which proves that the stability of this copper-silver nanowire aerogel current collector is very good.

[0074] Example 11

[0075] Take 1 kg of copper nanowires, hydroxypropyl cellulose, and ultrapure water, stir and mix them evenly in a mass ratio of 3:1:3, place them in a polytetrafluoroethylene mold, and freeze them with liquid nitrogen; freeze for 1 h to obtain solid gel B, and put solid gel B into a freeze dryer and dry for 48 h; after drying, remove the mold to obtain an ultra-light three-dimensional porous copper nanowire current collector.

[0076] The selected battery model is the 2032 button battery. Therefore, the diameter of the electrode sheet is set to 12 mm. A copper nanowire current collector is used as the positive electrode, and a lithium foil is used as the negative electrode to assemble a button battery. At the same time, with a current density of 1 mA cm-2 The current density is 1 mAh cm -2 Deposit to prepare a composite negative electrode of copper nanowire aerogel composite lithium metal with a lithium deposition amount of... Of course, in other embodiments, other battery models can also be selected, which is not limited here.

[0077] Assemble the composite negative electrode of copper nanowire aerogel composite lithium metal in a symmetric battery, and test its voltage hysteresis under a small current. The test value is 20 mV, which proves that the stability of this copper nanowire aerogel current collector is very good.

[0078] Example 12

[0079] Take 1 kg of copper nanowires, hydroxypropyl cellulose, and ultrapure water and stir and mix them evenly at a mass ratio of 3:1:2. Place them in a polytetrafluoroethylene mold and freeze them with liquid nitrogen; freeze for 1 h to obtain solid gel B, and then put solid gel B into a freeze dryer and dry it for 24 h; after drying, remove the mold to obtain an ultra-light three-dimensional porous copper nanowire current collector.

[0080] Select the battery model as a 2032-type button battery. Therefore, the diameter of the electrode sheet is set to 12 mm. Assemble a button battery with a copper nanowire current collector as the positive electrode and a lithium foil as the negative electrode. At the same time, with a current density of 1 mA cm -2 Deposit to prepare a composite negative electrode of copper nanowire aerogel composite lithium metal with a lithium deposition amount of 1 mAh cm -2 ... Of course, in other embodiments, other battery models can also be selected, which is not limited here.

[0081] Assemble the composite negative electrode of copper nanowire aerogel composite lithium metal in a symmetric battery, and test its voltage hysteresis under a small current. The test value is 21 mV, which proves that the stability of this copper nanowire aerogel current collector is very good.

[0082] In the above Examples 1 to 6 and 8 to 12, the composite negative electrode is prepared by the constant current electrochemical deposition method. Of course, the composite negative electrode can also be prepared by the melt thermal perfusion method. Example 7 uses the melt thermal perfusion method to prepare the composite negative electrode. Of course, the composite electrode can also be prepared by the constant current electrochemical deposition method, which is not limited here.

[0083] Please refer to Figure 2 As shown in the scanning electron microscope morphology of the metal nanowire aerogel current collector in..., the aerogel current collector after freeze-drying and demolding has a high-porosity network structure, and NWs-NWs junctions connected by van der Waals forces are connected into a complete conductive cross-linked network.

[0084] By repeatedly applying pressure and releasing pressure on the aerogel current collector to test the resilience of the aerogel current collector. In this embodiment, when pressure is applied, the thickness of the aerogel is about 1 cm. After the pressure is released, the aerogel can rebound to about 1.5 cm. That is to say, the aerogel current collector prepared in this embodiment has good resilience, high mechanical properties and specific surface area. The porosity of the aerogel current collector prepared by the preparation method of this application is measured by mercury intrusion method. After testing, the porosity of the aerogel current collector is 99%.

[0085] Please refer to Figure 3 and Figure 4 As shown, the half-cell Coulomb efficiency and symmetric cell test are carried out on the aerogel current collector prepared by this application. As the number of cycles increases, the Coulomb efficiency basically remains unchanged. As time extends, the voltage of the symmetric cell basically remains unchanged. That is to say, the aerogel current collector prepared by this application has good stability.

[0086] In summary, the negative electrode sheet of the three-dimensional porous ultra-light metal current collector obtained by the production method of the multi-metal nanowire aerogel current collector of the present invention can increase the specific surface area of the current collector and reduce the current density. It not only reduces the internal contact resistance between the metal and lithium, but also can effectively inhibit the formation of dendritic lithium, prevent safety problems such as short circuit caused during the cycling of the battery, greatly improve the safety, stability and life of the battery, and the metal nanowire aerogel is light in weight, can accommodate more lithium, reduces the mass of inactive substances, and improves the energy density of the battery. It not only simplifies the production operation, but also reduces pollution, energy consumption and cost.

[0087] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A preparation method of an aerogel current collector, characterized in that Including: Step 1: Stir and mix metal nanowires, a flocculant, and water in a mass ratio of n:1:m to obtain a hydrogel, where 1 ≤ n ≤ 10 and 1 ≤ m ≤ 10; Step 2: Place the hydrogel in a mold and freeze it for a certain time by liquid nitrogen and / or a refrigerator and / or a cold trap to obtain a solid gel; Step 3: Put the solid gel into a freeze dryer and dry it for 24 - 72 h to obtain an aerogel, and after demolding, obtain an ultra-light metal nanowire aerogel current collector; The metal nanowires in Step 1 are one or a combination of several of copper nanowires, silver nanowires, gold nanowires, copper-nickel alloy nanowires, nickel nanowires, and copper-silver alloy nanowires; The flocculant in Step 1 is one or a combination of several of polyvinylpyrrolidone, hydroxypropyl cellulose, lignin fiber, hydroxyethyl cellulose, and carboxymethyl cellulose.

2. The preparation method of the aerogel current collector according to claim 1, wherein: The water in Step 1 is deionized water.

3. The preparation method of the aerogel current collector according to claim 1, characterized in that: The ratio of the metal nanowires, flocculant, and water in Step 1 is 3:1:

3.

4. The preparation method of the aerogel current collector according to claim 1, wherein: The freezing time in Step 2 is 1 h, and the material of the mold is polytetrafluoroethylene.

5. The preparation method of the aerogel current collector according to claim 1, characterized in that: The drying time in Step 3 is 48 h.

6. A preparation method of a composite negative electrode, characterized in that: Using the ultralight metal nanowire aerogel current collector prepared by the method for preparing an aerogel current collector according to any one of claims 1-5 as the positive electrode and a lithium foil as the negative electrode, a composite negative electrode is prepared by deposition at a current density of 1 mA cm -2 and a lithium deposition amount of 1-10 mAh cm -2 .

7. A method for preparing a composite negative electrode, characterized in that: Melt metallic lithium under an inert gas, place the ultra-light metal nanowire aerogel current collector prepared by the preparation method of the aerogel current collector according to any one of claims 1 - 5 on the molten liquid metallic lithium, and apply pressure to make the liquid metallic lithium inhale into the grid structure of the ultra-light metal nanowire aerogel current collector to obtain a composite negative electrode.

8. The preparation method of the composite negative electrode according to claim 7, wherein: The inert gas is argon, and the temperature of the molten metallic lithium is 400 °C.

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