Preparation And Lithium Storage Properties Of Alloy/Graphite Composite Anode Materials

Since the birth of lithium-ion battery,due to its high working voltage,high energy density,and low environmental pollution,it has become an indispensable tool for promoting social development and improving the quality of life.The alloy anodes can accumulate a large amount of lithium without being restricted by crystal frame,which leads a huge advantage in terms of theoretical specific capacity.However,in the process of lithiation/de-lithiation,there will be a huge volume change,resulting in cracking and fracture of the material matrix,which limit the development of alloy-category anode materials.The current research on the modification of alloy anodes is mainly focused on improving the first cycle coulombic efficiency and cycling performance.The methods are nano particle size control,the use of carbon materials and other methods to suppress the volume expansion of the material,or the use of some metal and polymer materials with self-healing properties to repair the mechanical damage of the material.This article attempts to use ball milling to modify AlCuFe quasicrystals with carbon coating,and to use room temperature liquid metal GaInSn and graphite to prepare new self-healing materials.The main research contents are as follows:(1)In this paper,the mass ratio of quasicrystal and graphite is set to 1:1,and the surface of AlCuFe quasicrystal is modified by ball milling.By changing the rotation speed and time of ball milling,it is found that the carbon coating layer is well prepared.Optimal process to increase the lithium storage capacity of AlCuFe quasicrystal/C composite material and improve its cycling performance.The study found that the composite material prepared at 500r/min 60 h has a good carbon coating effect,and the carbon coating layer is uniform and no shedding occurs.The study on the lithium storage performance of the composite material has found that the specific capacity of the composite material varies with the increase in speed,which shows a trend of first rising and then falling,and with the increase of time,a trend of first falling and then rising.Among them,the 500r/min 60 h composite material has the highest specific capacity(239m Ah/g)and rate performance(higher than 150 m Ah/g at 2C).(2)To improve the coulombic efficiency of the first loop of GaInSn negative electrode,using a carbon coating layer to stabilize the SEI film.The GaInSn/C composite materials are prepared by using two different rotating speed of shear force stirring.Its electrochemical performance and self-repairing properties are researched which shows that the first columbic efficiency of the GaInSn/C composite prepared at2000r/min has been significantly improved(about 78%),and the material has shown good stability at a rate of 0.1C(about 68% capacity retention after 50 cycles)and rate performance(about 220 m Ah/g at 2C).The morphology of electrode materials at different stages of lithiation has been characterized and the good self-healing properties of liquid metal GaInSn have been observed.