Triggering highly conductive FePSe3 with Cu-based coordination towards all-climate ultrafast sodium ion storage

Limited by the relative radii of sodium ions (0.102 nm), sodium ion batteries suffer from sluggish kinetics. Owing to the high conductivity of selenium, Se-rich samples have captured plenty of attention. Herein, FePSe3 sheets were successfully prepared through vacuum tube sealing. Significantly, the as-resulted samples displayed considerable conductivity, further forming electrodes without conductive agents. Utilized as sodium ion storage anode with ether-based electrolytes, even at 20.0 A g(-1), the ultra-stable rate abilities could be retained at about 480 mA h g(-1) after 4000 cycles at room temperature (25 degrees C) and similar to 210 mA h g(-1) after 10 000 loops at low temperature (-30 degrees C). Assisted by a series of Cu2Se/Se samples, the strong coordination of Cu-atoms with DEGDME was noted, finally resulting in the formation of ultra-large coordination molecule Cu-(DEGDME)(n). From the detailed kinetic analysis, the coordination could offer rich shared electron pairs, inducing the quickening adsorption/desorption of ions, finally resulting in the remarkable pseudo-capacitive behavior Moreover, a detailed phase transformation (Cu-0 -> Cu1+ -> Cu2+) was carried out. Furthermore, the selection of glass fiber as separators was conducive to capturing NaPSes, improving the cycling stabilities. Given this, the work was anticipated to provide anion-rich materials for advanced SIBs anodes whilst shedding light on the in-depth reaction mechanism of metal-sulfide/selenides in ether-based electrolytes.

Automated summary

In this study, FePSe3 sheets were successfully prepared and exhibited considerable conductivity as anode material for sodium ion batteries. The strong coordination of Cu-atoms with DEGDME was also observed, leading to the formation of ultra-large coordination molecule Cu-(DEGDME)(n). Detailed kinetic analysis showed that this coordination facilitated the adsorption/desorption of ions, resulting in remarkable pseudo-capacitive behavior. The use of glass fiber separators improved the cycling stabilities. This work provides valuable insights into the development of anion-rich materials for advanced SIBs anodes and understanding of the reaction mechanism of metal-sulfide/selenides in ether-based electrolytes.