| Sodium ion batteries?SIBs?have attracted significant attentions as a promising alternative to lithium ion batteries?LIBs?for large-scale energy storage due to their inherent safety and the low cost of sodium.However,most of the anode materials suitable for LIBs cannot be directly used by SIBs due to severe losses in energy capacity and cycle stability.Therefore,a critical need for advancing SIBs is the development of suitable anodes.Alloying compounds?Ge?Sn?Pb?P?Sb?Bi?are proposed as new kinds of anode for SIBs in terms of its appropriate sodium insertion potentials,and high sodium storage capacity.Unfortunately,the rapid capacity loss originated from the large volume changes severely hinder its applications for SIBs.Sb has a two-dimension layered structure and is actually a graphite-like material.,and is considered as a promising candidate in terms of its appropriate sodium insertion potentials,flat charge-discharge plateau and high sodium storage capacity.Sb/C and NiSb/C composite prepared via an efficient and facile method with alginate as precursor have been evaluated as anode material for sodium ion batteries.Sb/C composite demonstrates high specific capacity(423.0 mAh g-1 at 0.1 A g-1),good rate capability(226.0 mAh g-1 at 15.0 A g-1),and excellent cycle life(81.4%capacity retention for 200 cycles at 2.0 A g-1).NiSb/C composite delivers a high reversible capacity(405.2 mAh g-1)and superior rate capability(247.7 mAh g-1 at 5.0 A g-1),as well as excellent cycling performance at 0.1 A g-1(404.9 m Ah g-1 after 100 cycles with a capacity retention of 100%)when evaluated as an anode for SIB.Sb2S3 has several advantages over pure Sb or other Sb-based composites,including greater gravimetric energy density,smaller volume change,and better cycling performance.These advantages are promising,but the long-term cyclability and rate capability of Sb2S3need to be further improved due to the poor electrical conductivity and unavoidable volume changes,which easily induce particle aggregation and pulverization.Herein,we report a facile approach toward high-performance Sb2S3/sulfur-doped graphene anodes?Sb2S3/SGS?for SIB by strong chemical binding of Sb2S3 on sulfur-doped graphene sheets?SGS?.The stronger affinity between Sb2S3 and SGS is verified by density functional theory?DFT?calculations,as characterized by a much higher adsorption energy of-2.15 eV.The composite exhibits an exceptionally stable capacity retention of 83.0%for 900 cycles at 2.0 A g-1 with high capacities and excellent high-rate response up to 5.0 A g-1.To the best of our knowledge,the performance of Sb2S3/SGS is superior to those reported for any other Sb-based materials for SIBs.SnS stand out to be the most promising candidates for hosting larger Na+because of their unique layered structure,smaller volume change and less phase transformation upon a sodiation/desodiation process,making it more suited for repeated cycling operations.However,SnS is a poor electrical conductor,a direct use of which would result in large polarizations and low utilization of SnS,and thus very poor electrical performance.Herein,we report a unique,facile and self-assembly method to fabricate an active and durable SnS/3D N-doped graphene?SnS/3DNG?hybrid SIB anode by utilizing poly?diallydimethylam-monium chloride??PDDA?to positively charge the surface of graphene oxide?GO?nanosheets that can significantly increase the electrostatic attraction to[SnS3]2-.As evidenced by experimental results and first-principles calculations,such a CMG provides ample efficient electron conducting channels and a platform for electrostatically anchoring SnS nanoparticles?NPs?without aggregation of SnS NPs during cycling.As a result,the hybrid anode shows unprecedented capacity retention rate of 87.1%for 1,000 cycles at 2.0 A g-1 with a high capacity of 509.9 m Ah g-1. |
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