Double phase tinoxide/tin/MWCNT nanocomposite negative electrodes for lithium microbatteries

As anode material for lithium microbatteries, Sno(2)/Sn/MWCNT nanocomposites were produced by two steps; thermal evaporation and subsequent plasma oxidation. Metallic tin was first evaporated onto free-standing MWCNT buckypapers having controlled porosity and subsequent RF plasma oxidized in Ar:O-2(1:1) gas mixture. The ratio between metallic tin (Sn) and tinoxide (SnO2) was controlled with plasma oxidation time. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to determine the structure and morphology of the obtained nanocomposites. The discharge/charge tests, electrochemical impedance spectroscopy (EIS) and rate capability tests were carried out to characterize the electrochemical properties of the composite. The flexible and free-standing SnO2/Sn/MWCNT nanocomposite electrode showed core-shell and functionally gradient composite structure. SnO2/Sn electrode was failed after 30 cycles and MWCNT paper electrode displays only 75 mAh g(-1) capacity value between 10 and 100 cycles. SnO2/Sn/MWCNT double phase electrode, exhibited 610 mAh g(-1) specific discharge capacity even after 100 cycles. (C) 2014 Elsevier B.V. All rights reserved.