Enhanced Electrochemical Performance of Electrospun Ag/Hollow Glassy Carbon Nanofibers as Free-standing Li-ion Battery Anode

Silver with a high theoretical capacity for lithium storage is an attractive alloy based anode for Li-ion batteries, but large volume changes associated with AgLix alloy formation leads to electrode cracking, pulverization and rapid capacity fading. A buffer matrix, like the electrospun hollow carbon nanofibers, can reduce this problem to a great extent. Herein, we demonstrate the facile synthesis of a free-standing, binder free Ag-C hybrid electrode through co-axial electrospinning, where well dispersed Ag nanoparticles are embedded in hollow carbon nanofibers. Using this approach, the long cycle life of carbon is complemented with the high lithium storage capacity of Ag, resulting in a high performance anode. The Ag-C composite electrode delivers a capacity of 739 mAh g(-1) (>conventional graphite anodes) at 50 mA g(-1), with similar to 85% capacity retention after 100 cycles. In addition, the Ag-C composite nanofibers are highly porous and exhibit a large accessible surface area (similar to 726.9 m(2) g(-1)) with an average pore diameter of similar to 6.07 nm. The encapsulation of Ag in the hollow interiors not only provides additional lithium storage sites but also enhances the electronic conductivity, which combined with the reduced lithium diffusion path lengths in the nanofibers result in faster charge-discharge kinetics and hence a high rate performance. (C) 2015 Elsevier Ltd. All rights reserved.