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Nitrogen-Doped CoSe2 as a Bifunctional Catalyst for High Areal Capacity and Lean Electrolyte of Li–S Battery
ACS Energy Letters ( IF 22.0 ) Pub Date : 2020-08-27 , DOI: 10.1021/acsenergylett.0c01564
Maoxu Wang 1 , Lishuang Fan 1 , Xun Sun 1 , Bin Guan 1 , Bo Jiang 1 , Xian Wu 1 , Da Tian 1 , Kening Sun 1 , Yue Qiu 1 , Xiaoju Yin 1 , Yu Zhang 1 , Naiqing Zhang 1
Affiliation  

The sluggish redox kinetics of polysulfides and difficult oxidation process of Li2S severely hinder practical application of Li–S batteries under high sulfur loading and a low electrolyte dosage. To address these issues, we develop a bifunctional catalyst by manipulation of anion N doping in CoSe2 (N-CoSe2). Theoretical simulation results uncover that an introduced N element into CoSe2 could form a shorter Co–N bond, create a higher charge number of the Co central atom, bring new defect levels, and induce the Co 3d band closer to Fermi level. Further atomic level analysis revealed that N-CoSe2 could form shorter Co–S bonds with sulfur species and simultaneously weaken the S–S bridged bond of Li2S4 and Li–S bond of Li2S, which eventually facilitate the polysulfide conversion reaction in the discharge process and the Li2S oxidation in the charge process. With N-CoSe2 as a bifunctional catalyst, the battery exhibited a high areal capacity of 9.26 mAh g–1 under the low E/S (electrolyte/sulfur) ratio of 4.4 μL mg–1. Understanding the design concept of a bifunctional catalyst with anion doping would provide a new vision for realizing a high-performance Li–S battery.

中文翻译:

掺氮CoSe 2作为双功能催化剂,用于高容量锂电池和稀薄电解质

多硫化物的氧化还原动力学迟缓和Li 2 S的氧化过程困难,严重阻碍了在高硫负荷和低电解质用量下Li-S电池的实际应用。为了解决这些问题,我们通过操纵CoSe 2(N-CoSe 2)中的阴离子N掺杂开发了一种双功能催化剂。理论仿真结果表明,向CoSe 2中引入N元素可以形成较短的Co–N键,产生较高的Co中心原子电荷数,带来新的缺陷能级,并诱导Co 3d能带更接近费米能级。进一步的原子级分析表明,N-CoSe 2可以与硫物种形成较短的Co-S键,同时削弱Li 2的S-S桥键。Li 2 S的S 4和Li–S键,最终促进了放电过程中的多硫化物转化反应和充电过程中的Li 2 S氧化。使用N-CoSe 2作为双功能催化剂,在4.4μLmg –1的低E / S(电解质/硫)比下,电池的单位面积容量为9.26 mAh g –1。了解带有阴离子掺杂的双功能催化剂的设计概念将为实现高性能Li-S电池提供新的视野。
更新日期:2020-09-11
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