Electrochimica Acta, Vol.52, No.28, 7820-7826, 2007
Advanced structures in electrodepo sited tin base anodes for lithium ion batteries
A novel composite anode material consisted of electrodeposited Sn dispersing in a conductive micro-porous carbon membrane, which was directly coated on Cu current collector, was investigated. The composite material was prepared by: (1) casting a polyacrylonitrile (PAN)/dimethylformamide (DMF) solution that contained silica particles on a copper foil, (2) removing the solvent by evaporation, (3) dissolving the silica particles by immersing the copper foil into an alkaline solution, (4) drying the copper foil coated by micro-porous membrane, (5) electrodepositing Sn onto the copper foil through the micro-pores in the micro-porous membrane, and (6) annealing as-obtained composite material. This method provided the composite material with high decentralization of Sn and supporting medium purpose of conductive carbon membrane deriving from pyrolysis of PAN. SEM, XRD and EDS analysis confirmed this structure. The characteristic structure was beneficial to inhibit the aggregation between Sn micro-particles, to relax the volume expansion during cycling, and to improve the cycleability of electrode. Galvanostatic tests indicated the discharge capacity of the composite material remained over 550 mAh g(-1) and 71.4% of charge retention after 30 cycles, while that of the electrode prepared by electrodepositing Sn on a bare Cu foil decreased seriously to 82.5 mAh g(-1) and 13%. These results show that the composite material is a promising anode material with larger specific capacity and long cycle life for lithium ion batteries. (C) 2007 Elsevier Ltd. All rights reserved.