Metastable Marcasite-FeS₂ as a New Anode Material for Lithium Ion Batteries: CNFs-Improved Lithiation/Delithiation Reversibility and Li-Storage Properties

Abstract

Marcasite (m-FeS) exhibits higher electronic conductivity than that of pyrite (p-FeS) because of its lower semiconducting gap (0.4 vs 0.7 eV). Meanwhile, as demonstrates stronger Fe-S bonds and less S-S interactions, the m-FeS seems to be a better choice for electrode materials compared to p-FeS. However, the m-FeS has been seldom studied due to its sophisticated synthetic methods until now. Herein, a hierarchical m-FeS and carbon nanofibers composite (m-FeS/CNFs) with grape-cluster structure was designed and successfully prepared by a straightforward hydrothermal method. When evaluated as an electrode material for lithium ion batteries, the m-FeS/CNFs exhibited superior lithium storage properties with a high reversible capacity of 1399.5 mAh g after 100 cycles at 100 mA g and good rate capability of 782.2 mAh g up to 10 A g. The Li-storage mechanism for the lithiation/delithiation processes of m-FeS/CNFs was systematically investigated by ex situ powder X-ray diffraction patterns and scanning electron microscopy. Interestingly, the hierarchical m-FeS microspheres assembled by small FeS nanoparticles in the m-FeS/CNFs composite converted into a mimosa with leaves open shape during Li insertion process and vice versa. Accordingly, a "CNFs accelerated decrystallization-recrystallization" mechanism was proposed to explain such morphology variations and the decent electrochemical performance of m-FeS/CNFs.

The application of nanostructured transition metal sulfides as anodes for lithium ion batteries

“…The pyrite owns the advantages of high theoretical energy density ( ∼ 1313 Wh kg −1 ), good thermal stability, low cost, earth abundant, nontoxic etc. Compared with other metal sulfides, the pyrite has been applied in Li-FeS 2 primary batteries long and successfully, and it would be more viable to develop commercial FeS 2based LIBs compared with other metal sulfides [59,117,118] .…”

Understanding the Li-ion storage mechanism in a carbon composited zinc sulfide electrode

“…[7][8][9][10][11] Thus, many sulde conversion materials (e.g., FeS 2 , NiS, CoS 2 , MnS, MoS 2 , and ZnS) have been studied as anode materials for LIBs. [12][13][14][15][16][17] Differing from other transitionmetals, lithium storage in the ZnS electrode relies not only on the redox conversion mechanism but also on the alloying mechanism. The formation of a Zn-Li alloy leads to a higher theoretical capacity (824.9 mA h g À1 ), compared to the one only based on the conversion mechanism (549.9 mA g À1 ).…”

Pseudocapacitive sodium storage of Fe1−xS@N-doped carbon for low-temperature operation

“…The capacity loss is mainly ascribed to the formation of SEI layer. These charge/discharge plots are well-overlapped over the subsequent cycles, implying the good reversibility of the Fe 1−x S@NC electrode [42]. Fig.…”

“…The Fe 1−x S@NC electrode remains a reversible capacity of 647.9 mA h g −1 with a high average CE of 99%. The slightly increased capacity is mainly attributed to two reasons: one is the activation effect, and the other is the formation of organic SEI film that can increase extra Na- storage sites via the alleged "pseudocapacitive behavior" [25,42,45]. In addition, the Fe 1−x S@CN electrode also exhibits a high capacity of~533.6 mA h g −1 at 3000 mA g -1 with stable capacity evolution (Fig.…”