Modification And Electrochemical Properties Of Sisal Fiber Carbon Materials

The biomass carbon has attracted extensive interest of researchers due to many advantages such as low cost,abundant reserves,no pollution and high capacity,and etc.,which has become a new type of anode material and can replace the existing graphitized materials for lithium battery.In this paper,the sisal fiber was chosen as the raw material.First,the hydrothermal modified sisal fiber carbon?HSFC?was prepared by a two-step hydrothermal method.And then,the iron oxide/HSFC composites were prepared by hydrothermal composition of HSFC and iron compound.The morphology,structure,adsorption properties and electrochemical performance as anode materials for lithium battery of the resulted material have been investigated.The main results are as follows:?1?The adsorption rate of HSFC is significantly higher than that of SFC.Under the same concentration of the acid solution,hydrothermal temperature,the adsorption rate of the samples treated with hydrochloric acid is better than that treated with sulfuric acid.The samples treated with 1mol/L hydrochloric at 160?showed a better adsorption performance to methylene blue dye,with a highest adsorption of 90%.Moreover,compared with SFC,the HSFC showed better adsorption performance to some ions like CrO₄^2-,Cu²⁺,Zn²⁺,and etc.,whose maximum adsorption capacity to CrO₄^2-reached 83mg/g.?2?The HSFC show a more disordered structure,and contain a large number of rare"spring like"spiral structures.Compared with the samples with direct carbonization,the surface area of HSFC increase about 101m²/g,and the number of mesoporous in it also increase significantly,in which the average pore diameter change from 1-2.0 nm to 15-20 nm.The results of electrochemical test show that the specific capacity of the modified carbon material is obviously increased,the initial capacity is increased from 710mAh/g to 1150mAh/g,and the coulombic efficiency is increased from 56.2%to 60.7%for the first time.After the 100 cycle,the specific capacity can be stabilized at around 570mAh/g,and can be maintained at 405mAh/g even at the current density of 500mA/g.?3?The iron oxide/HSFC composites were prepared by hydrothermal synthesis.Its morphology and electrochemical performance can be directly affected by hydrothermal temperature,calcination temperature and iron oxide loading ratio.The results of electrochemical test show that,with a Fe₂O₃ loading ratio of 25%and a hydrothermal temperature of 130?,the coulombic efficiency of the composite materials is 63%for the first time,and can be maintained at 595mAh/g after 50 cycles.The Fe₃O₄/HSFC composite calcinated at 600?exhibit the best electrochemical performance:the first coulombic efficiency is 64%and the capacity is still maintained at 610mAh/g after 50 cycles,and a specific capacity of 480 mAh/g can be maintained after 50 cycles with a current density of 500mA/g.Therefore,the composite modification is an effective method to improve the electrochemical properties of carbon materials.