Preparation And Electrochemical Performance Study Of SnO₂ Anode Material For Lithium-Ion Battery

SnO₂ is one of the promising novel anode materials for lithium-ion battery. However, the poor cycle performance of material becomes the bottleneck to any further application. The anode material with nanosized and functionalization is considered as an appropriate candidate.A series of SnO₂ anode materials were synthesized by solvothermal method combined with template method. The structure of SnO₂ was characterized by XRD, FE-SEM, BET, FT-IR and UV-Vis. The galvanostatic charge-discharge and alternating current impedance methods were used to study the electro- chemical performance of materials. The influence of solvothermal temperature, solvothermal time, carbon content, solvent system, carbon source, Ni²⁺-doped SnO₂ and SnO₂/C composite on microstructure, first charge-discharge and cycle performance of materials was systematically investigated. The aim of this part was to determine the optimum processing condition, doping amount of Ni²⁺ and addition content of carbon for SnO₂.SnO₂/C precursor was prepared at 180℃for 24 h in the solvothermal condition, using glucose:SnCl4=20 mmol:8 mmol as reactant and water:ethanol =20 mL:50 mL as solvent system. The precursor was then calcined at 550℃for 5 h in air. The results revealed that calcined product had tetragonal rutile structure. The zero-dimensional SnO₂ spherical nanoparticles were successfully assembled into a higher-order structure of three-dimensional microporous sphere. The SnO₂ sphere had a BET surface area of 36.41 m²/g, with an average BJH pore diameter of 15.8 nm and a pore volume of 0.211 cm³/g.SnO₂ had a high first discharge specific capacity of 896.1 mAh/g and the capacity retention rate was 39.76% of initial capacity after 50 cycles at the charge-discharge current rate of 0.1C. The coulombic efficiency was above 90% from the fourth cycle. The first discharge specific capacity was 628.1 mAh/g with the capacity retention rate of 66.98% of initial capacity after 30 cycles at 0.5C rate. SnO₂ exhibited good reversibility, cycle and rate performance due to the structure of three-dimensional microporous sphere. The capacity retention rates of SnO₂ doped with 7 mol%Ni²⁺ and SnO₂/C composite with 50 wt.%C were 52.85% and 69.22% of initial capacity, respectively, after 50 cycles at the rate of 0.2C. It was suggested that Ni²⁺-doped SnO₂ and SnO₂/C composite exhibited better cycling stability than that of pure SnO₂.