Baek GY  Jeong SM  Na BK

Vol. 22,  No. 4, pp. 308-315, Dec.  2016
10.7464/ksct.2016.22.4.308

Lithium secondary batteries Anode materials Sol-Gel Silicon

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SiOx/ZnO composites were prepared from sol-gel method for excellent cycle life characteristics. The composites were coated by PVC as a carbon precursor. ZnO removal to create a void space therein was able to buffer the volume change during charge and discharge. To determine the crystal structure and the shape of the synthesized composite, XRD, SEM, TEM analysis was performed. The carbon contents in the composites were confirmed by TGA. The pore structure and pore size distribution of the composite was measured with the BET specific surface area analysis and BJH pore size distribution. Enhanced electric conductivity by carbon addition was determined from powder resistance measurement. Electrochemical properties were measured with the AC impedance and the charge and discharge cycle life characteristics. When carbon was coated on the SiOx/ZnO sample, the electrical conductivity and the discharge capacity were increased. After removal of ZnO with HCl the surface area of the sample was increased, but the discharge capacity was decreased. SiOx/ZnO sample without acarbon coating showed very low discharge capacity, and after carbon coating the sample showed high discharge capacity. For cycle life characteristics, C-SiOx/ZnO composite (Zn : Si : C = 1 : 1 : 8) with a capacity of 815 mAh g-1 at 50 cycle and 0.2 C has higher capacity than existing graphite-based anode materials.