Research On Lithium Storage Performance And Modification Of Two-dimensional Al-Cu-Co10-fold Quasicrystal

Lithium-ion batteries are widely used in portable electronic devices,electric vehicles,aerospace,military and other fields because of their high capacity and cycle-stable.However,it still has some safety problems,such as battery swelling,short circuit caused by diaphragm puncture,etc.The embedded anode material is a material with smaller volume expansion and better safety among many anode materials.The two-dimensional 10-fold quasicrystal Al-Cu-Co is a periodic sheet-like material.Lithium ions may be stored between the layers.However,the lithium storage mechanism of two-dimensional 10-fold quasicrystals is still unclear.In this paper,two-dimensional 10-fold quasicrystals Al₆₅Cu₂₀Co₁₅ and Al₆₄Cu₂₂Co₁₄ are selected as the research objects,using XRD,SEM,TEM,STEM and in-situ TEM to study the morphology and microstructure of quasicrystals,and explore the quasicrystals Lithium storage performance and mechanism as a battery's negative electrode material.The innovative research results obtained in this article are summarized in the following aspects:(1)Al₆₅Cu₂₀Co₁₅ and Al₆₄Cu₂₂Co₁₄ quasicrystal materials were prepared by the arc furnace method,and the lithium storage performances of them in the heat-treated and unheated state were studied.The as-cast Al₆₅Cu₂₀Co₁₅ quasicrystal morphology is irregular granular,which shows a reversible capacity with 150 m Ahg^-1.The heat treatment Al₆₅Cu₂₀Co₁₅ quasicrystal material presents a regular spherical morphology with a low specific capacity,which is not conducive to rapid charge and discharge at a high rate,and the internal resistance of the heat-treated Al₆₅Cu₂₀Co₁₅ quasicrystal becomes smaller.The unheated Al₆₄Cu₂₂Co₁₄ quasicrystal exhibits an irregular granular morphology and has a reversible capacity with 52 m Ahg^-1.The heat-treated Al₆₄Cu₂₂Co₁₄ quasicrystal has a lower specific capacity,but the expansion rate is larger,and the internal resistance of the heat-treated Al₆₄Cu₂₂Co₁₄ quasicrystal becomes larger.These materials have maintained a reversible capacity of more than 90%after 1000cycles,and exhibited expansion phenomenon,and presented good structural stability.(2)The in-situ microscopic nano battery charge/discharge test was carried out on the unheated Al₆₅Cu₂₀Co₁₅ quasicrystal by using a transmission electron microscope.The morphologies during the in-situ charging and discharging process showed that the quasicrystal material had no significant volume expansion occurred during the charging and discharging process.The in-situ electron diffraction results showed that the electron diffraction pattern did not change,indicating that the structure of the quasicrystal did not change during the charge and discharge process.The results of Al₆₅Cu₂₀Co₁₅quasicrystal after charge and discharge with 1000 cycles which characterized by TEM and HAADF showed that the morphology and periodic lamellar structure of Al₆₅Cu₂₀Co₁₅ quasicrystal material did not change.(3)Owing to its low electrical conductivity of Al₆₄Cu₂₂Co₁₄ quasicrystal,carbon composite method has been taken to solve the problem of its small specific capacity.Composite materials were prepared by using carbonized bovine serum albumin(CBSA)and reduced graphene oxide(RGO)as carbon sources which has good conductivity.The experimental results showed that the CBSA composite material had a smaller reversible capacity and internal resistance,which was more conducive to the rapid charge and discharge at a high rate.Even the RGO composite material has a higher specific capacity,but it did not show an excellent capacity expansion like the original quasicrystal due to the limitation of the nature of the RGO material.The research results will provide a certain reference for the modification of quasicrystal materials as battery anode materials.