Composite lithium metal negative electrode material and preparation method thereof

Abstract

The invention discloses a composite lithium metal negative electrode material and a preparation method thereof. The preparation method comprises the following steps: in the inert atmosphere, adding metal lithium and other metal into an alloy smelting furnace to be smelted; keeping the temperature unchanged, and adding an electric field with a certain intensity into the smelting furnace to make elements in the molten liquid uniformly distributed to obtain a first molten liquid; adding an Mxene material into the first molten liquid; continuously keeping the temperature and the voltage unchangedfor 1-5 hours to obtain a second molten liquid; pouring the second molten liquid into a mold, cooling to room temperature, keeping the mold in the magnetic field, and cooling to obtain a composite metal lithium plate; and molding the metal lithium plate to obtain a composite metal lithium strip with controllable thickness. According to the prepared composite negative electrode material, the rate capability is remarkably improved, the cycle life is remarkably prolonged, and the lithium dendritic crystal problem is obviously improved, so that the safety performance of a battery is greatly improved.

Description

[0001] Technical solutions [0002] The invention relates to the technical field of lithium batteries, in particular to a composite lithium metal negative electrode material and a preparation method thereof. Background technique [0003] With the continuous development of science and technology, the demand for high energy density power supply is getting higher and higher. At present, batteries that can theoretically provide high energy density include lithium-air batteries, lithium-sulfur batteries and lithium metal batteries, which are considered to be the most promising next-generation batteries. A generation of high specific energy batteries. Lithium metal anode is considered to be the most potential anode material because of its extremely high theoretical specific capacity (3860mAh·g-1) and extremely negative potential (-3.040Vvs standard hydrogen electrode). [0004] However, there are still many problems in the large-scale application of metal lithium anodes: during the...

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Problems solved by technology

[0004] However, there are still many problems in the large-scale application of metal lithium anodes: during the charging and discharging process, due to the high activity of metal lithium anodes and the uneven deposition of lithium ions, lithium dendrites are easily grown on the surface, thus piercing the separator. The short circuit causes thermal runaway, which leads to serious safety accidents. At the same time, the "dead lithium" formed after the dendrite breaks will reduce the Coulombic efficiency. Instability, leading to chalking of the material, which shortens battery life

[0006] With the increasing demand for high-energy-density power supplies, many researchers have turned their attention to metal lithium anode materials. Although the mass-energy density has been improved to a certain extent, there are still unresolved problems: Due to the high activity of the lithium metal negative electrode and the uneven deposition of lithium ions, lithium dendrites are easily grown on the surface, which can pierce the separator and cause a short circuit to cause thermal runaway, causing serious safety accidents. "Dead lithium" will reduce the Coulombic efficiency. During the charging and discharging process, the metal lithium itself has no skeleton characteristics, which will cause a huge volume change, resulting in the instability of the negative electrode structure, resulting in material pulverization, and shortening the service life of the battery.

In the previous research work, a lot of research has been done on this series of problems, but fundamentally this series of problems has not been solved well.

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