Defect engineering on carbon black for accelerated Li-S chemistry
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i National Laboratory for Physical Sciences at Microscale and Department of Chemistry, University of Science and Technology of China, Hefei 230026, China 2 State Key Laboratory of Environment-Friendly Energy Materials, School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, China © Tsinghua University Press and Springer-Verlag GmbH Germany, part of Springer Nature 2020 Received: 9 May 2020 / Revised: 23 July 2020 / Accepted: 26 July 2020
ABSTRACT Rationally designing sulfur hosts with the functions of confining lithium polysulfides (LiPSs) and promoting sulfur reaction kinetics is critically important to the real implementation of lithium–sulfur (Li–S) batteries. Herein, the defect-rich carbon black (CB) as sulfur host was successfully constructed through a rationally regulated defect engineering. Thus-obtained defect-rich CB can act as an active electrocatalyst to enable the sulfur redox reaction kinetics, which could be regarded as effective inhibitor to alleviate the LiPS shuttle. As expected, the cathode consisting of sulfur and defect-rich CB presents a high rate capacity of 783.8 mA·h·g−1 at 4 C and a low capacity decay of only 0.07% per cycle at 2 C over 500 cycles, showing favorable electrochemical performances. The strategy in this investigation paves a promising way to the design of active electrocatalysts for realizing commercially viable Li–S batteries.
KEYWORDS Li–S chemistry, defect engineering, carbon black, sulfur reaction kinetics
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Introduction
Owing to the overwhelming theoretical capacity (1,672 mA·h·g−1), high energy density (2,600 W·h·kg−1), and low cost of sulfur, lithium–sulfur (Li–S) batteries have been regarded as one of the most promising next-generation energy storage devices [1–5]. However, the practical application of Li–S batteries have been impeded by a multitude of issues: (i) the noticeable volume variation (80%) during the continuous and repetitive transformation between sulfur and lithium sulfide; (ii) the low utilization of active materials due to the poor electronic/ionic conductivity; (iii) the notorious shutting effect of soluble lithium polysulfides (LiPSs) between the electrodes; (iv) the resultant side reactions at lithium anode side [6–10]. In recent years, extensive efforts have been devoted to addressing the above-mentioned problems for facilitating the commercialization of Li–S batteries [11–14]. Of the many alternatives, optimizing sulfur electrochemical process has been confirmed as an effective strategy to mitigate the shuttle phenomenon [15–18]. Carbonaceous materials, such as porous carbon [19], graphene [20], and carbon nanotube [21], were used at the earliest to confine LiPSs by physical adsorption. Nevertheless, such weak van der Waals affinity is insufficient to stabilize LiPSs. In this case, polar groups were introduced into carbon host, resulting in the strong polar–polar interaction with LiPSs [22–24]. Thus far, wide investigations reveal that the polar hosts should present the functions of both confi
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