Synthesis And Electrochemical Performance Of Anode Materials (Sulfide-Based Materials?Biomass Carbon) For Lithium-Ion Battery

In this paper,Cu₂ZnSnS₄?MoS₂ and WS₂,as well as biomass carbon were studied as anode materials for lithium-ion battery.The synthesis,modification,structure and electrochemical properties of these materials were also studied.The properties of novel Cu₂ZnSnS₄ and biomass carbon as anodes are our highlights in this paper.The important conclusions were drawn from our expriments.The main contents are listed as follows:1.The precursors of three dimensional kesterite Cu₂ZnSnS₄?CZTS?microstructures were firstly synthesized by a facile solvothermal method using Cu?NO₃?₂·3H₂O,Zn?NO₃?2·6H₂O,SnCl₂·2H₂O and CH₄N₂S as raw materials,and oxalic acid was used as additive agent.The as-synthesized precursors were further annealed at a low temperature in argon atmosphere to obtain the expected CZTS microstructures.And the effect of oxalic acid on the crystal structure,morphology and formation mechanism as well as electrochemical properties of the as-synthesized products were also investigated in depth.The structure and morphology of the expected samples are characterized by X-ray diffraction,Raman spectroscopy,X-ray photoelectron spectroscopy,scanning electron microscopy and transmission electron microscopy techniques,and its electrochemical properties were tested by galvanostatic charge/discharge system and AC impedance measurement.The results show that the Cu₂ZnSnS₄?CZTS?takes on morphology of microspheres with ultrathin nanosheet constituents and has a stoichiometric composition.As a novel anode material for lithium ion batteries,the as-prepared CZTS microstructures synthesized in OA can maintain a high capacity of 786mAhg-1 after 100 cycles,exhibiting both high reversible capacity and good cycling performance at room temperature under a potential window from 3.0 to 0.01 V?vs.Li+/Li?at current density of 100mAg-1.The mechanism of the electrochemical reactions in the electrode was also investigated,which provides experimental basis for developing novel anode material with high specific capacity and excellent cycling performances for lithium-ion battery.2.MoS₂ nano-structures were prepared through a facile one-pot hydrothermal method followed by a low temperature annealing process.The structure and morphology of the expected samples were characterized by X-ray diffraction,X-ray photoelectron spectroscopy and scanning electron microscopy technique,and its electrochemical properties were tested by galvanostatic charge/discharge system and AC impedance measurement.The results reveal that the as-prepared MoS₂ microstructures exhibit high reversible capacity,while the cycling performance is poor.The MoS₂/C composites were synthesized by hydrothermal method using carbon spheres as a template.It has the same structure as that of pure MoS₂.The electrical conductivity of MoS₂/C composites was increased significantly,thus behaved better cycling performances than that of pure MoS₂ nanostrctures.As a novel anode material for lithium ion batteries,the achieved discharge capacity can be retained at 705mAhg-1 after 165 cycles at room temperature under a potential window from 3.0 to 0.01 V?vs.Li+/Li?at current density of 100mAg-1.Furthermore,the mechanism of the electrochemical reactions in the electrode was investigated,which showed that the charge/discharge plateau had little change,while the charge transfer resistance of the MoS₂/C electrode was decreased obviously,and the lithium ion diffusion in this electrode was faster,thus,the MoS₂/C possessed excellent electrochemical properties.3.The precursors of amorphous WS₂/C composites were synthesized by a facile one-pot hydrothermal method using Na₂WO₄·2H₂O?H₂C₂O₄ and CH₃CSNH₂ as raw materials,and polyethylene glycol with molecular weight as 20000 was used as dispersant,as well as using glucose as carbon source.The as-synthesized precursors were further annealed at a low temperature in argon atmosphere to obtain the expected samples.The structure and morphology of the expected samples are characterized by X-ray diffraction,X-ray photoelectron spectroscopy and scanning electron microscopy techniques.The electrochemical properties were tested by galvanostatic charge/discharge system and AC impedance measurement.The results reveal that as a novel anode material for lithium ion batteries,the as-prepared amorphous WS₂/C composites exhibit both high reversible capacity and good cycling performance at room temperature under a potential window from 3.0 to 0.01 V?vs.Li+/Li?at current density of 100mAg-1.The achieved initial discharge capacity was 1080mAhg-1 and retained at 786mAhg-1 after 170 cycles.What is more important is that the amorphous WS₂/C composites exhibited lower charge/discharge plateau,which is more beneficial for being used as an anode for lithium ion battery application.The cyclic voltammetry?CV?and AC impedance test further confirmed the plateau change and the decrease of charge transfer resistance in the WS₂/C electrode.And the chemical formation process and electrochemical mechanism of WS₂/C the composites were also analysized in brief presently.The good electrochemical performance suggests that the amorphous WS₂/C composites could be a promising candidate as a novel anode material for lithium ion battery applications.4.Three-dimensional?3D?rod-like carbon micro-structures derived from natural ramie fibers and two-dimensional?2D?carbon nanosheets derived from corncobs have been fabricated by high temperature pyrolysis under argon atomsphere.The structure and morphology of the expected samples are characterized by X-ray diffraction,Raman spectroscopy,scanning electron microscopy and transmission electron microscopy techniques,and their electrochemical properties were tested by galvanostatic charge/discharge system.The results show that both biomass carbon electrodes exhibit excellent lithium storage properties,especially for the nanosheets derived from corncobs which possess a high reversible capacity and superior cycling performance,achieving a high capacity of 606 mAhg-1 after 180 cycles.In addition,both electrodes present the same cycling properties when tested as anodes in sodium ion batteries.And the electrochemical mechanism of the biomass carbon were also analysized through cyclic voltammetry?CV?and AC impedance test.The good electrochemical performance suggests that both biomass carbon could be a promising candidate as a novel anode materials.