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Promoting the Transformation of Li 2 S 2 to Li 2 S: Significantly Increasing Utilization of Active Materials for High‐Sulfur‐Loading Li–S Batteries
Author(s) -
Yang Xiaofei,
Gao Xuejie,
Sun Qian,
Jand Sara Panahian,
Yu Ying,
Zhao Yang,
Li Xia,
Adair Keegan,
Kuo LiangYin,
Rohrer Jochen,
Liang Jianneng,
Lin Xiaoting,
Banis Mohammad Norouzi,
Hu Yongfeng,
Zhang Hongzhang,
Li Xianfeng,
Li Ruying,
Zhang Huamin,
Kaghazchi Payam,
Sham TsunKong,
Sun Xueliang
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.201901220
Subject(s) - polysulfide , sulfur , cobalt sulfide , materials science , sulfide , electrochemistry , catalysis , amorphous solid , chemical engineering , lithium–sulfur battery , electrode , organic chemistry , metallurgy , chemistry , electrolyte , engineering
Lithium–sulfur (Li–S) batteries with high sulfur loading are urgently required in order to take advantage of their high theoretical energy density. Ether‐based Li–S batteries involve sophisticated multistep solid–liquid–solid–solid electrochemical reaction mechanisms. Recently, studies on Li–S batteries have widely focused on the initial solid (sulfur)–liquid (soluble polysulfide)–solid (Li 2 S 2 ) conversion reactions, which contribute to the first 50% of the theoretical capacity of the Li–S batteries. Nonetheless, the sluggish kinetics of the solid–solid conversion from solid‐state intermediate product Li 2 S 2 to the final discharge product Li 2 S (corresponding to the last 50% of the theoretical capacity) leads to the premature end of discharge, resulting in low discharge capacity output and low sulfur utilization. To tackle the aforementioned issue, a catalyst of amorphous cobalt sulfide (CoS 3 ) is proposed to decrease the dissociation energy of Li 2 S 2 and propel the electrochemical transformation of Li 2 S 2 to Li 2 S. The CoS 3 catalyst plays a critical role in improving the sulfur utilization, especially in high‐loading sulfur cathodes (3–10 mg cm −2 ). Accordingly, the Li 2 S/Li 2 S 2 ratio in the discharge products increased to 5.60/1 from 1/1.63 with CoS 3 catalyst, resulting in a sulfur utilization increase of 20% (335 mAh g −1 ) compared to the counterpart sulfur electrode without CoS 3 .