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Anchoring polysulfides in hierarchical porous carbon aerogel via electric-field-responsive switch for lithium sulfur battery
Electrochimica Acta ( IF 5.5 ) Pub Date : 2018-10-11 , DOI: 10.1016/j.electacta.2018.10.054
Jingjian Yu , Xueliang Li , Yizhen Shu , Li Ma , Xingchi Zhang , Yunsheng Ding

Lithium sulfur batteries have attracted significant attention owing to their remarkably high theoretical capacities and energy density for the potential next-generation energy storage system. Considerable efforts have been developed to improve the redox reversibility and suppress sulfur loss when maintaining their capacities. However, few strategies have enlightened to address shuttle issues via electric-field-responsive film. Here, we postulate a new strategy to create smart electric-field-responsive surface structure and design special molecular film with quaternary ammonium group. The responsive film bonded to carbon matrix can act as a switch to control the on-off of polysulfide channels. Meanwhile, the prepared carbon aerogel (CA) matrix presents highly cross-linked 3D framework, abundant hierarchical pore channels and high specific surface area. The results show the composite sulfur cathode with selective film exhibits outstanding high discharging capacities and long-term cycling stability. Specifically, the cathode with 61.6 wt% sulfur displays an initial specific capacity of 1307 mAh g−1 at 0.2C and maintains 84.0% after 100 cycles. The improved electrochemical performance may mainly benefit from the switch function of self-responsive film, effectively preventing polysulfides escaping from the cathode, suppressing shuttle effect and enhancing the utilization of sulfur. Furthermore, the adsorption calculation by the density functional theory (DFT) shows trapping role of beta-cyclodextrin quaternary ammonium (CDQA) to polysulfides. The DFT simulation further supports the confining and switching mechanism.



中文翻译:

通过电场响应开关将多硫化物固定在分层多孔碳气凝胶中,用于锂硫电池

锂硫电池由于其极高的理论容量和潜在的下一代储能系统的能量密度而备受关注。在保持其容量时,已经进行了相当大的努力以改善氧化还原可逆性并抑制硫的损失。但是,很少有策略可以通过电场响应胶片解决穿梭问题。在这里,我们提出了一种新的策略来创建智能的电场响应表面结构,并设计具有季铵基团的特殊分子膜。结合到碳基质上的响应膜可以充当开关,以控制多硫化物通道的通断。同时,制备的碳气凝胶(CA)基质具有高度交联的3D框架,丰富的分层孔隙通道和高比表面积。结果表明,具有选择膜的复合硫阴极具有优异的高放电容量和长期循环稳定性。具体而言,具有61.6 wt%硫的阴极显示的初始比容量为1307 mAh g-1在0.2C时,在100个循环后保持84.0%。改善的电化学性能可以主要得益于自响应膜的转换功能,有效地防止多硫化物从阴极逸出,抑制穿梭效应并提高硫的利用率。此外,通过密度泛函理论(DFT)进行的吸附计算表明,β-环糊精季铵盐(CDQA)对多硫化物具有捕集作用。DFT仿真进一步支持约束和切换机制。

更新日期:2018-10-11
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