Synthesis and performance testing of cobalt-zinc bimetallic sulfide microsphere anode materials
The low capacity of graphite anode materials in current commercial lithium batteries limits their use in applications such as high-power devices. Metal sulfides are inexpensive,have high theoretical capacity and excellent physicochemical properties,and are potentially advantageous for application as anode materials in lithium-ion batteries. However,the cycling performance and multiplication performance crossover are the main obstacles to the large-scale application of metal sulfides. Compared with monometallic sulfides,bimetallic sulfides have richer spatial structures and more variable compositions,with richer redox reaction potentials,higher electrochemical activities,and higher conductivities. In this paper,with the aim of finding and developing new electrode materials for bimetallic sulphides with high capacity density,long cycle life and high multiplicity performance,samples of cobalt-zinc bimetallic sulphide (CoZn2S4) were synthesised by a simple hydrothermal method at 100,150 and 200 ℃. The synthesized cobalt-zinc bimetallic sulphide (CoZn2S4) samples were analytically characterised and tested for electrochemical properties using X-ray powder diffraction,scanning electron microscopy,and energy dispersive X-ray spectroscopy. It was found that CoZn2S4 has a porous microstructure,and the porous microstructure of the synthesised CoZn2S4 at 150 and 200 ℃ is better,which can improve the contact area of the electrode material with the electrolyte and provide extra space to accommodate the volume change during electrochemical charging and discharging.At a current density of 100 mA/g,the synthesised CoZn2S4 at 200 ℃ has an initial discharging capacity,an initial charging capacity were 1038.7 and 1296.2 mA·h/g,respectively,and the initial discharge capacity and initial charging capacity of the synthesised CoZn2S4 at 150 ℃ were 497.7 and 757.6 mA·h/g,respectively,and it still exhibited a reversible capacity of 931.8 mA·h/g with a capacity retention of 69％ after 100 cycles. The results showed that the reversibility,cycling performance,and multiplicity performance were better when cobalt-zinc bimetallic sulfide (CoZn2S4) was synthesised as the anode material for lithium batteries at 200 ℃.
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