Covalently encapsulating sulfur chains into carbon-rich nanomaterials towards high-capacity and high-rate sodium-ion storage

Abstract

Synchronously achieving high-capacity and high-rate sodium-ion storage is critical for large-scale energy stationary application of sodium-ion batteries (SIB). Here we present a facile bottom-up strategy to covalently encapsulate sulfur chains...

High-sulfur-doped hard carbon for sodium-ion battery anodes with large capacity and high initial coulombic efficiency

“…Interestingly, a new peak appears at a very low binding energy of $159.6 eV when the electrode is under a discharge state of 0.3 V. This peak becomes stronger once discharged to 0.01 V and weakens during the charging process, and nally disappeared. This can be attributed to the reversible formation and disassembly of Na x S. 14 To conrm this, the XRD pattern of the carbon electrode discharged to 0.01 V is recorded and given in Fig. 5d, in which a clear peak located at 38.9 appears, corresponding to the (220) crystal plane of Na 2 S crystals (PDF#65-2995).…”

“…Such a discharge plateau also has been observed in a number of related publications. 11,12 c ,14 In the initial charge branch, a plateau around 1.75 V appears, corresponding to the reversible Na extraction from the carbon framework. It is notable that the initial discharge and charge capacities are 921 and 777 mA h g −1 , among the highest values of current carbon anodes for sodium ion batteries.…”

“…It is notable that the initial discharge and charge capacities are 921 and 777 mA h g −1 , among the highest values of current carbon anodes for sodium ion batteries. 7 a , e ,12 c ,14,19 Without doubt, this high capacity originates from the loading of S atoms, which is able to provide enough additional Na storage sites in the carbon framework. In addition, it is more important that the ICE of this SHC-500 electrode reaches 84.4%, higher than that of most of the state-of-the-art S-doped carbon anodes.…”

“…22), S-doped carbon nanosheets (S–CNS ref. 12c), and some other S-doped amorphous carbon materials (KEC-600, 14 S–HC–p ref. 23 and SC ref.…”

“…13 A similar method was reported by knitting 3,4-ethylenedioxythiophene (EDOT) with external crosslinking reactants, which endowed the elaborate anode material with a high capacity of 456 mA h g À1 . 14 These methods have achieved great success in designing high-performance hard carbon anodes. However, exploiting a simple and effective method to construct carbon anodes with an ultrahigh S content is still a big challenge.…”