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Controllable Chain‐Length for Covalent Sulfur–Carbon Materials Enabling Stable and High‐Capacity Sodium Storage
Author(s) -
Wu Tianjing,
Jing Mingjun,
Yang Li,
Zou Guoqiang,
Hou Hongshuai,
Zhang Yang,
Zhang Yu,
Cao Xiaoyu,
Ji Xiaobo
Publication year - 2019
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201803478
Subject(s) - sulfur , covalent bond , carbon fibers , materials science , chemical engineering , ionic bonding , sulfide , cathode , inorganic chemistry , chemistry , ion , organic chemistry , composite number , composite material , metallurgy , engineering
Room temperature sodium–sulfur batteries have emerged as promising candidate for application in energy storage. However, the electrodes are usually obtained through infusing elemental sulfur into various carbon sources, and the precipitation of insoluble and irreversible sulfide species on the surface of carbon and sodium readily leads to continuous capacity degradation. Here, a novel strategy is demonstrated to prepare a covalent sulfur–carbon complex (SC‐BDSA) with high covalent‐sulfur concentration (40.1%) that relies on SO 3 H (Benzenedisulfonic acid, BDSA) and SO 4 2− as the sulfur source rather than elemental sulfur. Most of the sulfur is exists in the form of OS/CS bridge‐bonds (short/long‐chain) whose features ensure sufficient interfacial contact and maintain high ionic/electronic conductivities of the sulfur–carbon cathode. Meanwhile, the carbon mesopores resulting from the thermal‐treated salt bath can confine a certain amount of sulfur and localize the diffluent polysulfides. Furthermore, the CS x C bridges can be electrochemically broken at lower potential (<0.6 V vs Na/Na + ) and then function as a capacity sponsor. And the R‐SO units can anchor the initially generated S x 2− to form insoluble surface‐bound intermediates. Thus SC‐BDSA exhibits a specific capacity of 696 mAh g −1 at 2500 mA g −1 and excellent cycling stability for 1000 cycles with 0.035% capacity decay per cycle.