Pyrite (FeS₂) nanocrystals as inexpensive high-performance lithium-ion cathode and sodium-ion anode materials

Abstract

In light of the impeding depletion of fossil fuels and necessity to lower carbon dioxide emissions, economically viable high-performance batteries are urgently needed for numerous applications ranging from electric cars to stationary large-scale electricity storage. Due to its low raw material cost, non-toxicity and potentially high charge-storage capacity pyrite (FeS2) is a highly promising material for such next-generation batteries. In this work we present the electrochemical performance of FeS2 nanocrystals (NCs) as lithium-ion and sodium-ion storage materials. First, we show that nanoscopic FeS2 is a promising lithium-ion cathode material, delivering a capacity of 715 mA h g(-1) and average energy density of 1237 Wh kg(-1) for 100 cycles, twice higher than for commonly used LiCoO2 cathodes. Then we demonstrate, for the first time, that FeS2 NCs can serve as highly reversible sodium-ion anode material with long cycling life. As sodium-ion anode material, FeS2 NCs provide capacities above 500 mA h g(-1) for 400 cycles at a current rate of 1000 mA g(-1). In all our tests and control experiments, the performance of chemically synthesized nanoscale FeS2 clearly surpasses bulk FeS2 as well as large number of other nanostructured metal sulfides.

Mechanism and Solution for the Capacity Fading of Li/FeS2Battery

“…6, suggesting that the FeS formed by charging is either amorphous or in very small particle size. 4,8 After 200 cycles (Fig. 3d), the FeS 2 cathode does not show any XRD peaks except for two small peaks of the Al substrate, revealing that (1) the FeS formed by charging is either amorphous or in very small particle size and (2) no sufficient amount of Li 2 S n can be formed due to the loss of sulfur active material during repeated cycling.…”

“…1-4. Li 2−x FeS 2 − (2 − x) e − → (2 − x) Li + + FeS n + (2 − n) S x ≥ 0.8 [4] The first discharge of Li/FeS 2 cells has been intensively investigated and well understood. Under the thermodynamic equilibrium condition that is typically obtained by either reducing FeS 2 particle size or lowering the current density, the first discharge follows a Li + intercalation (Eq.…”

“…8 After this, the resultant sulfur serves as an independent cathode material and hence induces the same problems as observed in the conventional Li/S cells, such as dissolution of lithium polysulfide (Li 2 S n with n > 2), redox shuttle, and other resultant parasitic reactions. 15 Based on the above redox mechanism, the C-FeS 2 composites [16][17][18][19][20][21] and carbon-modified/wrapped FeS 2 materials [22][23][24][25] with various novel structures, such as nanocrystals, 4 microspheres 26,27 and core-shell structures, 28 have been widely synthesized to improve the cyclability and power capability of the Li/FeS 2 cells. On the other hand, the solid-state electrolyte, 11,[29][30][31][32] polymer composite electrolyte, 6,11,29,30 and ionic liquid 33 have been proposed to prevent the dissolution of Li 2 S n .…”

In Situ Construction of 3D Interconnected FeS@Fe3C@Graphitic Carbon Networks for High‐Performance Sodium‐Ion Batteries

“…[9][10][11][12][13][14][15] Among them, iron sulfide (FeS) undergoes a sodiation/ desodiation process via the following reaction: FeS + 2Na + 2e − → Na 2 S + Fe, offering a high theoretical capacity of 609 mA h g −1 . [9][10][11][12][13][14][15] Among them, iron sulfide (FeS) undergoes a sodiation/ desodiation process via the following reaction: FeS + 2Na + 2e − → Na 2 S + Fe, offering a high theoretical capacity of 609 mA h g −1 .…”

Recent Advances in Sodium-Ion Battery Materials

“…The discharge process involved a Na + insertion reaction above 0.8 V and a subsequent conversion reaction below 0.8 V [214,215]. When cycled in low-potential region, the FeS 2 electrode exhibited a high reversible capacity of 900 mAh g −1 and long stable cyclic life [216]. Lou and co-workers designed unique FeS 2 @C yolk-shell nanoboxes with a long cycle life over 800 cycles (Fig.…”