High-performance Sn@carbon nanocomposite anode for lithium-ion batteries: Lithium storage processes characterization and low-temperature behavior

The electrochemical behavior of a composite anode for Li-ion batteries, based on nanosize tin particles embedded in electrically conducting porous multichannel carbon microtubes (Sn-PMCMT), synthesized by co-electrospinning, is here evaluated. An activation protocol aimed at maximizing anode mechanical stability and capacity retention upon cycling is presented. The results are compared with those obtained with an anode using pristine PMCMT carbon as active material. The Li uptake and release processes by Sn and C are evaluated by galvanostatic charge/discharge cycles, in order to differentiate the two contributions to the overall anode capacity. Electrochemical impedance spectroscopy (EIS) analysis is utilized in order to evaluate possible improvements to charge-transfer kinetics due to the nanosize Sn particles dispersion. Finally, the performances of the composite Sn-PMCMT anode are characterized at different charge/discharge currents and temperatures. The anode can deliver a capacity of 500 mAh g(-1) for more than 300 cycles, most of them at 1C or higher charge/discharge rate, which confirms its very high, stable cycling performances. Moreover, this tailored nanostructured anode retains a relevant amount of capacity even in very demanding cycling conditions, as the case for very low temperatures. These results make the proposed Sn-PMCMT an ideal candidate anode for high-performance Li-ion batteries able to operate in a wide array of operating conditions. (C) 2013 Elsevier Ltd. All rights reserved.