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Toward Theoretically Cycling-Stable Lithium–Sulfur Battery Using a Foldable and Compositionally Heterogeneous Cathode

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posted on 27.11.2017, 00:00 authored by Lei Zhong, Kai Yang, Ruiteng Guan, Liangbin Wang, Shuanjin Wang, Dongmei Han, Min Xiao, Yuezhong Meng
Rechargeable lithium–sulfur (Li–S) batteries have been expected for new-generation electrical energy storages, which are attributed to their high theoretical energy density, cost effectiveness, and eco-friendliness. But Li–S batteries still have some problems for practical application, such as low sulfur utilization and dissatisfactory capacity retention. Herein, we designed and fabricated a foldable and compositionally heterogeneous three-dimensional sulfur cathode with integrated sandwich structure. The electrical conductivity of the cathode is facilitated by three different dimension carbons, in which short-distance and long-distance pathways for electrons are provided by zero-dimensional ketjen black (KB), one-dimensional activated carbon fiber (ACF) and two-dimensional graphene (G). The resultant three-dimensional sulfur cathode (T-AKG/KB@S) with an areal sulfur loading of 2 mg cm–2 exhibits a high initial specific capacity, superior rate performance and a reversible discharge capacity of up to 726 mAh g–1 at 3.6 mA cm–2 with an inappreciable capacity fading rate of 0.0044% per cycle after 500 cycles. Moreover, the cathode with a high areal sulfur loading of 8 mg cm–2 also delivers a reversible discharge capacity of 938 mAh g–1 at 0.71 mA cm–2 with a capacity fading rate of 0.15% per cycle and a Coulombic efficiency of almost 100% after 50 cycles.