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Sulfur‐Grafted Hollow Carbon Spheres for Potassium‐Ion Battery Anodes
Author(s) -
Ding Jia,
Zhang Hanlei,
Zhou Hui,
Feng Jun,
Zheng Xuerong,
Zhong Cheng,
Paek Eunsu,
Hu Wenbin,
Mitlin David
Publication year - 2019
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201900429
Subject(s) - faraday efficiency , materials science , potassium ion battery , anode , carbon fibers , sulfur , electrochemistry , diffusion , electrode , battery (electricity) , chemical engineering , potassium , titration , inorganic chemistry , chemistry , composite material , power (physics) , physics , quantum mechanics , composite number , metallurgy , thermodynamics , lithium vanadium phosphate battery , engineering
Sulfur‐rich carbons are minimally explored for potassium‐ion batteries (KIBs). Here, a large amount of S (38 wt%) is chemically incorporated into a carbon host, creating sulfur‐grafted hollow carbon spheres (SHCS) for KIB anodes. The SHCS architecture provides a combination of nanoscale (≈40 nm) diffusion distances and CS chemical bonding to minimize cycling capacity decay and Coulombic efficiency (CE) loss. The SHCS exhibit a reversible capacity of 581 mAh g −1 (at 0.025 A g −1 ), which is the highest reversible capacity reported for any carbon‐based KIB anode. Electrochemical analysis of S‐free carbon spheres baseline demonstrates that both the carbon matrix and the sulfur species are highly electrochemically active. SHCS also show excellent rate capability, achieving 202, 160, and 110 mAh g −1 at 1.5, 3, and 5 A g −1 , respectively. The electrode maintains 93% of the capacity from the 5th to 1000th cycle at 3 A g −1 , with steady‐state CE being near 100%. Raman analysis indicates reversible breakage of CS and SS bonds upon potassiation to 0.01 V versus K/K + . The galvanostatic intermittent titration technique (GITT) analysis provides voltage‐dependent K + diffusion coefficients that range from 10 −10 to 10 −12 cm 2 s −1 upon potassiation and depotassiation, with approximately five times higher coefficient for the former.