Lithium-sulfur battery have been considered as promising energy storage devices because of its superiority in energy density. However, the low active material utilization, low sulfur loading, shuttle effect and torpid kinetics of polysulfides, and poor cycling stability limit its commercial applications. Herein, the functionalized nitrogen doped carbon nanofibers containing amide groups were designed by electrospun and polyamidoamine dendrimer (PAMAM) solution impregnation techniques. The obtained amide groups modified nitrogen-doped carbon nanofibers (ANF) were combined with spinel CoFe2O4 (CFO) nanoparticles (CFOANF) via hydrothermal method to design as membrane electrode containing Li2S6 catholyte for lithium-sulfur batteries. The introduction of nitrogen doped and amide groups modified ANF can increase fibers polarity, which have chemical adsorption capability toward lithium polysulfides. CFO nanoparticles can further absorb the soluble polysulfides by strong chemical interaction due to its intrinsic polarity and also serve as a catalyst to promote the redox kinetics of polysulfides conversion. Benefiting from the synergism of the physical confinement, polar chemical adsorption, and catalytic conversion, the as-prepared CFOANF delivers excellent electrochemical performances at high sulfur loading. The as-prepared CFOANF membrane with 6.3 mg cm−2 sulfur loading delivers a high initial capacity of 940 mAh g−1 and excellent long-term cycling stability up to 450 cycles with a low decay rate 0.059 % per cycle at 0.2C. Remarkably, even at 12.6 mg cm−2 and 16.4 mg cm−2 sulfur loading, the CFOANF membrane electrodes show high capacity of 9.7 mAh cm−2 and 11.8 mAh cm−2, respectively. The results show that the chemically anchoring polysulfides and catalyzing redox reaction by multifunctional CFOANF hybrid composite is promising for assembling with a high sulfur loading electrode, which exhibits a superior electrochemical performance in lithium-sulfur batteries.

中文翻译：

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CoFe2O4纳米颗粒修饰氮掺杂碳纳米纤维混合催化剂的酰胺化加速高硫负载量锂硫电池的电化学动力学


锂硫电池因其能量密度的优越性而被认为是有前途的储能装置。然而，多硫化物活性物质利用率低、硫负载量低、穿梭效应和动力学迟钝以及循环稳定性差限制了其商业应用。在此，通过静电纺丝和聚酰胺胺树枝状聚合物（PAMAM）溶液浸渍技术设计了含有酰胺基团的功能化氮掺杂碳纳米纤维。通过水热法将所得酰胺基改性氮掺杂碳纳米纤维（ANF）与尖晶石CoFe2O4（CFO）纳米颗粒（CFOANF）复合，设计用于锂硫电池的含Li2S6正极电解液的膜电极。引入氮掺杂和酰胺基团改性的ANF可以增加纤维的极性，对多硫化锂具有化学吸附能力。 CFO纳米颗粒由于其固有的极性，可以通过强化学相互作用进一步吸收可溶性多硫化物，并且还可以作为催化剂促进多硫化物转化的氧化还原动力学。受益于物理限制、极性化学吸附和催化转化的协同作用，所制备的CFOANF在高硫负载量下具有优异的电化学性能。所制备的硫负载量为 6.3 mg cm−2 的 CFOANF 膜具有 940 mAh g−1 的高初始容量和高达 450 个循环的出色长期循环稳定性，在 0.2C 下每个循环的衰减率为 0.059%。值得注意的是，即使硫负载量为 12.6 mg cm−2 和 16.4 mg cm−2，CFOANF 膜电极也分别显示出 9.7 mAh cm−2 和 11.8 mAh cm−2 的高容量。 结果表明，多功能CFOANF杂化复合材料化学锚定多硫化物并催化氧化还原反应，有望用于组装高硫载量电极，在锂硫电池中表现出优异的电化学性能。