Synergistic anode materials based on crystalline Fe3O4 nanoparticles supported over different carbon matrices

E. PRIMO; M. V. BRACAMONTE; G. L. LUQUE; L. VENOSTA; P. G. BERCOFF; D. E. BARRACO

Workshop; II WLiME 2016: 3rd International Workshop on Lithium, Industrial Minerals and Energy; 2016

In order to fulfil the rapidlygrowing demand for lithium-ion batteries (LIB) with higher energy density andlong cycle life, transition-metal oxides have been investigated as promisinghigh-capacity anodes [1]. Among them, magnetite (Fe3O4)is a natural occurring mineral found in the earth?s crust and is also easy tosynthesize through simple and non-hazardous techniques. Complete reduction of Fe3O4involves the transfer of 8 electrons, providing a theoretical capacity of 925mAhg-1 [2]. As the completeutilization of the electroactive metalcenters can be challenging for a densely structured material as Fe3O4,which doesn?t have well defined layers or tunnel for facile Li+insertion, the utilization of nano-sized Fe3O4 hybridstructures is almost mandatory.In this work, we report a study of cabon materials (C), with differentparticle sizes, used as support for magnetite nanoparticles (NPs) to obtain Fe3O4-Chybrids. The obtained hybrids were characterized as a function of the carbonsupport and were used for the development of anodes for LIBs. The cyclabilityand charge-discharge profiles were compared taking into advantage the capacityof lithiation of both Fe3O4 NPs and carbon. The carbon samples used (C1 and C2) were of different sizes; and Fe3O4NPs(~12 nm) are mainly located at the edges of thestructures; as determined by SEM micrographs and Raman analysis. Hysteresisloops obtained through magnetometric measurements showed that the Fe3O4wt%of e3O4-C1 hybrid was 16% while of Fe3O4-C2was 9%.When used as anode materials, Fe3O4-C1 and Fe3O4-C2samples exhibit 2 different regions when cycling them between 3.000 and 0.010V. The first one (around 0.700 V) corresponds to the lithiation of Fe3O4NPs and the formation of Li2O and metallic Fe. The second one(around 0.100 V) arises from the intercalation of Li ions in the graphiticplanes. As a consequence, both constituents play a synergistic role in thelithium uptake and observed capacity profile.Fe3O4-C1anode retains its specific capacity after cycling the battery several timeswhile Fe3O4-C2 loses its capacity up to half of theinitial one in the first cycles. This suggests that the differences in Fe3O4content and carbon material size play a major role in the performance of theLIB.In conclusion, Fe3O4-Chybrid materials were synthesized, producing Fe3O4NPswhich are uniformly dispersed over the carbon surfaces. The Fe3O4-Chybrids with different sizes were employed for the development of anodes forLIB. A synergistic effect between the magnetite lithiation conversion reactionand the graphite lithium intercalation was observed. We also concluded that Fe3O4loading and carbon material size determines the LIB cyclability.Acknowledgments:Authorswould like to thank CONICET, Y-TEC, SeCyT-UNC and ANPCyT for the fellowship andgrants. References: [1]F. Wu, J.Bai, J. Feng, S. Xiong, Nanoscale, 7(2015) 17211-17230[2] A. M. Bruck, C. A. Cama, C. N. Gannett, A. C. Marschilok, E. S.Takeuchi, K. J. Takeuchi, InorganicChemistry Frontiers, 3 (2016) 26-40