Preparation And Electrochemical Properties Of Micro-expansion Carbon Microsphere Composites

In this paper,micro-expanded microspheres with large interlayer spacing were prepared by low-temperature oxidation and hydrothermal reduction.A type of Sn-C composite materials has been fabricated by using hydrothermal reduction.The prepared materials were characterized by scanning electron microscopy,transmission electron microscopy,X-ray diffraction,X-ray photoelectron spectroscopy,Raman spectroscopy,galvanostatic charge and discharge tests,cyclic voltammetry and AC impedance measurements.And structure and electrochemical properties of the samples were analyzed and studied.The expanded microspheres were successfully prepared by hydrothermal reduction at low temperature,and the expanded microspheres could be effectively controlled by changing the temperature of hydrothermal reduction,and the sphere structure of carbon microspheres could be adjusted effectively.The expanded carbon microspheres material structure remains intact.And they showed a good electrochemical properties and excellent cycle performances in sodium ion battery.The maximum specific capacity and cycling performance of the expanded carbon microspheres treated at 180℃ were obtained.And,the expanded carbon microspheres anode exhibited a large reversible capacity of 199.2 mAh/g and capacitance retention rate of more than 90%after 1000 cycles at 100 mA/g.As the anode material of Li-ion battery,the expanded carbon microspheres with higher reversible capacity were hydrothermally reduced at 150℃ and 180℃.At the current density of 20mA/g,the charge-specific capacity was 698.7 mAh/g,664.3 mAh/g,much higher than the actual specific capacity of graphite.The Sn-C composite materials with different composite contents were prepared successfully.The best cycling performance and a good specific capacity were obtained when the mass ratio of tin to carbon was 1:1.After 220 cycles,the specific capacity reached 550 mAh/g at current density of 100 mA/g.the capacitance retention rate of 95%,with excellent cycle performance.The Sn-C composite materials has a good rate performance at high current density 1A/g,the discharge specific capacity of 230.3 mAh/g.