A kind of 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, comprising the following steps: adding metal lithium and other metals into an alloy melting furnace for melting under an inert atmosphere; keeping the temperature unchanged, and applying an electric field of a certain strength to In the smelting furnace, the elements in the molten liquid are uniformly distributed to obtain the first molten liquid; the Mxene material is added to the first molten liquid; the temperature and voltage are kept unchanged for 1 to 5 hours to obtain the second molten liquid; The second molten liquid is poured into a mold and cooled to room temperature, the mold is placed in a magnetic field, and a composite metal lithium plate is obtained after cooling; the metal lithium plate is shaped to obtain a composite metal lithium strip with a controllable thickness. The prepared composite negative electrode material significantly improves its rate performance and cycle life, and significantly improves the lithium dendrite problem, resulting in a significant improvement in the safety performance of the battery.

Description

technical field [0001] 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 [0002] 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. Metal lithium anode is considered to be the most potential anode material with its extremely high theoretical specific capacity (3860 mAh g-1) and extremely negative potential (-3.040Vvs standard hydrogen electrode). [0003] However, there are still many problems in the large-scale application of metal lithium anodes: during the charging and di...

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Problems solved by technology

[0003] 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 brings serious safety accidents. At the same time, the "dead lithium" formed after dendrite fracture will reduce the Coulombic efficiency. Instability, leading to chalking of the material, which shortens battery life

[0005] 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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