Monoatomic dispersed MXene materials and applications in lithium battery negative electrodes

Abstract

The invention discloses a monatomic dispersed MXene material and applications in lithium battery negative electrodes. The monatomic dispersed MXene material is characterized in that single doped metalatoms are dispersed on the surface of the sheet layer of the monoatomic dispersed MXene material, and can realize controllable nucleation growth of metal lithium in an initial metal lithium deposition stage; lithium tends to nucleate uniformly on the MXene layer containing single doped atoms, originates from a large number of doped metal atoms, and then grows vertically along the nucleation position due to a strong electric field at the edge so as to form bowl-shaped lithium and even blocky lithium, so that the growth of lithium dendrites is avoided; and when the monatomic dispersed MXene material is used as a metal lithium negative electrode, the monatomic dispersed MXene material is a dendrite-free metal lithium negative electrode, and the negative electrode has low overpotential, longcycle life and deep dissolution deposition plating performance. According to the invention, based on mature roll-to-roll and spraying technologies, the metal lithium negative electrode can be easily expanded in scale so as to substantially benefit the development of lithium batteries in the future.

Description

technical field [0001] The invention belongs to the field of new materials, and more specifically relates to an MXene material with monoatomic dispersion on the surface and its use in lithium battery negative electrodes. Background technique [0002] In recent years, with the rapid development of mobile devices, vehicle electrification, grid storage, 5G information transmission technology, biochips and wearable electronic devices, commercial lithium-ion batteries using graphite as the negative electrode have been difficult to meet the needs of applications. Lithium metal has become one of the most potential negative electrode materials for lithium-based batteries. Lithium metal has the most negative electrochemical potential (about -3.04V compared to the standard hydrogen electrode) and up to 3860 mAh g -1 Theoretical specific capacity, almost the commercial graphite anode material (372mAh g -1 ) 10 times. However, in the process of repeated charging and discharging of met...

AI Technical Summary

Problems solved by technology

However, in the process of repeated charging and discharging of metal lithium negative electrode, dendrites are easy to form due to uneven deposition at the interface. With the growth of dendrites, it is possible to pierce the separator and cause a short circuit of the battery, causing safety problems. In addition, it will affect its metal. The problem with the cycle performance of the lithium anode is that the skeletonless nature of the lithium metal itself during charging and discharging will produce a huge volume change that leads to the instability of the negative electrode structure, and the high chemical reduction of the lithium metal also leads to the formation of a fragile solid electrolyte. Interfacial (SEI) membrane, depleted lithium and liquid electrolyte

These problems will lead to short cycle life, low coulombic efficiency, low energy density, and even short-circuit safety accidents of lithium-based batteries, hindering the further practical application of lithium-based batteries.

[0003] In order to deal with the problem that lithium metal anodes are prone to produce lithium branched crystals during charging and discharging, the current technical routes mainly include: (1) preparing a three-dimensional (3D) matrix with stable performance and good electrical conductivity and compounding with metal lithium to obtain metal Lithium composite materials promote the uniform plating of lithium metal during charge and discharge, such as rGO film-Li, carbon nanotube foam-Li, 3D Cu foam-Li and 3D Ni network-Li, etc., but such materials have a large number of porous structures , usually showing low Coulombic efficiency and low volumetric capacity; (2) is an improved SEI film, such as composite graphene film, alloy layer, MoS 2 layers, MXenes or polymers, etc., or adding additives in the electrolyte, such as LiF, polysulfide or fluoroethylene carbonate (FEC), etc., to grow a stable and uniform SEI film in situ

The improved SEI film obtained by this type of technical route can effectively protect the metal lithium anode from electrolyte corrosion, but this type of improved SEI film is difficult to resist the stress caused by the huge volume change of the metal lithium anode, which eventually leads to poor cycle performance; (3) Select suitable materials to control the nucleation and growth of lithium metal, such as designing a suitable structure and selecting efficient nucleating agents, such as Au, Ag or Zn. Laboratory stage, but this type of technical route is expected to become an effective way to obtain dendrite-free metal lithium anodes

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