Zhang Xuzi, Shang Chaoqun, Akinoglu Eser Metin, Wang Xin, Zhou Guofu
Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays South China Academy of Advanced Optoelectronics South China Normal University Guangzhou 510006 China.
International Academy of Optoelectronics at Zhaoqing South China Normal University Zhaoqing 526060 China.
Adv Sci (Weinh). 2020 Oct 11;7(22):2002037. doi: 10.1002/advs.202002037. eCollection 2020 Nov.
Lithium-sulfur batteries (LSBs) have shown great potential as a rival for next generation batteries, for its relatively high theoretical capacity and eco-friendly properties. Nevertheless, blocked by the shuttle effect of lithium polysulfides (LPSs, LiS-LiS) and insulation of sulfur, LSBs show rapid capacity loss and cannot achieve the practical application. Herein, a composite of carbon nanofibers coated by CoS nanosheets (denoted as CNF@CoS) is successfully synthesized as freestanding sulfur host to optimize the interaction with sulfur species. The combination of the two materials can lead extraordinary cycling and rate performance by alleviating the shuttle of LPSs effectively. N-doped carbon nanofibers serve as long-range conductive networks and CoS nanosheets can accelerate the conversion of LPSs through its electrocatalytic and chemical adsorption ability. Benefiting from the unique structure, the transporting rate of Li can be enhanced. Distribution of Li is uniform for enough exposed negative active sites. As a result, the cell with CNF@CoS as sulfur host is able to stabilize at 710 mA h g at 1 C after 200 cycles with average coulombic efficiency of 97.8% in a sulfur loading of 1.7 mg cm and deliver 4.1 mA h cm at 0.1 C even in 6.8 mg cm for 100 cycles.
锂硫电池（LSBs）因其相对较高的理论容量和环保特性，已展现出作为下一代电池竞争对手的巨大潜力。然而，受多硫化锂（LPSs，LiS-LiS）的穿梭效应和硫的绝缘性阻碍，锂硫电池表现出快速的容量损失，无法实现实际应用。在此，一种由CoS纳米片包覆的碳纳米纤维复合材料（记为CNF@CoS）被成功合成，作为独立的硫宿主以优化与硫物种的相互作用。这两种材料的结合通过有效减轻LPSs的穿梭效应，可带来卓越的循环性能和倍率性能。氮掺杂碳纳米纤维作为长程导电网络，而CoS纳米片可通过其电催化和化学吸附能力加速LPSs的转化。受益于独特的结构，Li的传输速率得以提高。由于有足够暴露的负极活性位点，Li的分布均匀。结果，以CNF@CoS作为硫宿主的电池在硫负载为1.7 mg cm²时，1 C下200次循环后能够稳定在710 mA h g，平均库仑效率为97.8%，甚至在硫负载为6.8 mg cm²时，0.1 C下100次循环可提供4.1 mA h cm² 。
