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Investigation on lithium conversion behavior and degradation mechanisms in Tin based ternary component alloy anodes for lithium ion batteries
, A. Mitra, P.P. Dahiya, A. Kumar, M. Mallik, K. Das, S.B. Majumder, S. Das
Published in Elsevier Ltd
Volume: 721
Pages: 236 - 248
In this article, we investigate into the ternary tin based alloy, thin film anodes for lithium ion batteries, specifically into Sn-Sb-Cu system, synthesized via electrodeposition. The alloy electrodes show a stable discharge capacity of ∼600 mAh g−1 discharged at a rate of 200 mA g−1 (∼0.3C) for 50 cycles. FESEM images show a nano-dendritic, porous microstructure which can help in accommodating high volume expansion during lithiation and prevent the problem of pulverization. The phases present in the prepared anodes are Sn, SnSb and Cu6 Sn5 which are all active towards lithium insertion and extraction. The behavior of this multi-phase alloy system is examined using X-ray diffraction measurements. At extremely slow discharge rates, the phases take up lithium at distinct potentials with reactions with SnSb, Cu6Sn5 and Sn occurring at 0.86 V, 0.65 V and 0.45 V, respectively. A mechanism, where a lithiated phase decomposes and internally supplies lithium to the reacting phase, is observed and thereby lowering the total specific capacity of the anode as a whole when discharged. EIS measurements further reveal that there is degradation in the reaction kinetics with increasing cycles. Finally, failure of the anode is investigated and the cause is identified as the delamination of active material from the current collector. The problem is successfully removed by replacing Copper current collector with Silver current collector, where the intermetallic composition reacts at a lower voltage than Tin. Cycling the anode above this cutoff voltage removes the problem of delamination. However, it is identified that the existing electrolyte composition in the market, used for graphite anodes, is incompatible with Tin based anodes. © 2017
About the journal
JournalData powered by TypesetJournal of Alloys and Compounds
PublisherData powered by TypesetElsevier Ltd