Abstract
Graphene/sulfur@graphene composite structure as a cathode material is synthesized with a facile method. Graphene can provide a more efficient conductive network for sulfur and improve the coulombic efficiency of the battery. On the other hand, it may also show the anchoring effect on sulfur, which reduces the loss of sulfur and improves the cycling performance of the battery. Due to the unique structure, the initial discharge capacity of a battery assembled with this structure could reach 1036 mAh g−1 at 0.1 C, and its reversible capacity of 619 mAh g−1 was retained after 200 cycles with a low fading rate of 0.2% per cycle. The battery could hold a discharge capacity of 501 mAh g−1 after 200 cycles at 0.5 C. Thus, the electrochemical performance improved because of the reduction of sulfur loss through polysulfide accumulation at the cathode.
Highlights
High-energy-density rechargeable batteries are essential for various applications, such as portable electronic devices and grid-scale renewable energy storage, especially electric vehicles [1]
S is covered by G layers and protected to a certain extent, but many S losses still occurred during the cycle
S was further protected by adding a layer of G, which could provide more attachment points for active substances and to a certain extent alleviate the shuttle effect
Summary
High-energy-density rechargeable batteries are essential for various applications, such as portable electronic devices and grid-scale renewable energy storage, especially electric vehicles [1]. The volume of S expands up to 80% during discharge, causing the positive electrode to be powdered and the batteries to fail [1, 3,4,5,6,7] To alleviate these problems and improve the electrochemical performance of Li-S batteries, researchers extensively investigated the cathodes, anodes, electrolytes, and separators of Li-S batteries. In studies on cathode materials, especially structural designs, many interesting structures, such as coaxial carbon nanotube structure [20,21,22,23], dual-core shell structure [24,25,26], and plane hierarchical structure [11, 27,28,29], have been proposed, and the Journal of Nanomaterials electrochemical performance of Li-S batteries has been effectively improved. EIS tests were performed at a frequency range of 0.01–100 kHz with a perturbation amplitude of 5 mV at 25°C
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