Highly symmetric gigaporous carbon microsphere as conductive host for sulfur to achieve high areal capacity for lithium–sulfur batteries

• Published in: Journal of power sources Vol. 451; p. 227818
• Main Authors: Cho, Chuan-Sheng, Chang, Jin-Yu, Li, Chia-Chen
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-03-2020
• Subjects: Areal capacity; Cathode; Li-S battery; Porous microsphere; Li-S battery; Cathode; Areal capacity; Porous microsphere
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2020.227818

We propose a gigaporous carbon microsphere, given its large surface area and high porosity, as a novel host for sulfur infusion and a potential cathode active material for Li–S batteries. Because the infused sulfur is distributed and confined in the three-dimensional, connected carbon network of the porous microsphere, an electrode made of this material shows very high conductivity. In addition, as the synthesized carbon microsphere is polar and a good adsorbent for polar polysulfides, it improves battery performance by reducing loss of sulfur and suppressing the shuttle effect. The battery constructed using this material shows high cell performance with a highly stable capacity at ~1000 mAh g−1 under a charge/discharge current of 0.2C for 200 cycles and a Coulombic efficiency of 100%. After 200 charge/discharge cycles the electrode retains good structural integrity, which is an important cause for the insignificant increase in the ionic and electronic impedances of the battery. Moreover, a simple increase in the sulfur loading of the electrode to 6 mg cm−2 with the addition of electrolyte in a moderate electrolyte/sulfur ratio of 5 μL mg−1 can effectively achieve a practical areal capacity > 3–4 mAh cm−2 at 0.1–0.3C.
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•A new porous composite of sulfur and carbon is constructed.•High porosity from the new composite provides a high loading volume for sulfur.•Using the composite as cathode active material yields greatly improved conductivity.•Improved utilization of sulfur and weaker shuttle effect are achieved.•Cell performance with good rate-capability and cycle-life is obtained.