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Tuning of interactions between cathode and lithium polysulfide in Li-S battery by rational halogenation
Journal of Energy Chemistry ( IF 14.0 ) Pub Date : 2020-02-25 , DOI: 10.1016/j.jechem.2020.01.015
Samson O. Olanrele , Zan Lian , Chaowei Si , Shuo Chen , Bo Li

Li–S batteries have aroused intense interests as one of the most promising high-energy-density storage technology. However, the complex undesired shuttle effect induced by dissolution and diffusion of lithium polysulfide intermediates remains the major setback of this technology. Chemical modification of carbon cathode through heteroatom-doping is widely accepted as an effective method to inhibit the shuttle effect in Li-S battery cathode. Herein, using first principle calculations, we systematically examined the interaction between halogenated graphene and lithium polysulfide species. It is found that the halogen dopants (F, Cl, Br, I) significantly modify the local electronic structure of adsorption site and further induce a polarization to trap the polysulfides. Interestingly, a concave curve is observed from F to I for lithium polysulfide adsorption rather than a linear relation. The exceptions demonstrated from iodine dopant is carefully analyzed and attributed to its unique charge state. Moreover, boron as second dopant further strengthens the interaction between halogenated graphene and polysulfide molecule. Based on halogenation strategy, lithium polysulfide/cathode interactions are tuned in a wide range, which can also be of great importance to accelerate redox reaction in Li-S battery. Overall, an effective method by halogenation is verified to regulate the adsorption of lithium polysulfide and also enhance the reaction kinetics of the Li-S battery system.



中文翻译:

通过合理的卤化作用来调节Li-S电池中阴极与多硫化锂之间的相互作用

锂离子电池作为最有前途的高能量密度存储技术之一,引起了人们的浓厚兴趣。然而,由多硫化锂中间体的溶解和扩散引起的复杂的不希望的穿梭效应仍然是该技术的主要挫折。通过杂原子掺杂对碳阴极进行化学修饰被广泛认为是抑制Li-S电池阴极穿梭效应的有效方法。在本文中,我们使用第一性原理计算系统地研究了卤代石墨烯与多硫化锂物质之间的相互作用。发现卤素掺杂剂(F,Cl,Br,I)显着改变了吸附位的局部电子结构,并进一步引起极化以捕获多硫化物。有趣的是 从F到I观察到凹曲线是多硫化锂的吸附,而不是线性关系。仔细分析了碘掺杂剂显示的异常,并将其归因于其独特的电荷状态。此外,硼作为第二掺杂剂进一步增强了卤代石墨烯与多硫化物分子之间的相互作用。基于卤化策略,多硫化锂/阴极相互作用的调节范围很广,这对于加速锂-硫电池的氧化还原反应也具有重要意义。总的来说,已证明通过卤化的有效方法可调节多硫化锂的吸附,并增强Li-S电池系统的反应动力学。硼作为第二掺杂剂进一步增强了卤代石墨烯与多硫化物分子之间的相互作用。基于卤化策略,可广泛调节多硫化锂/阴极的相互作用,这对于加速锂-硫电池的氧化还原反应也具有重要意义。总的来说,已证明通过卤化的有效方法可调节多硫化锂的吸附,并增强Li-S电池系统的反应动力学。硼作为第二掺杂剂进一步增强了卤代石墨烯与多硫化物分子之间的相互作用。基于卤化策略,多硫化锂/阴极相互作用的调节范围很广,这对于加速锂-硫电池的氧化还原反应也具有重要意义。总的来说,已证明通过卤化的有效方法可调节多硫化锂的吸附,并增强Li-S电池系统的反应动力学。

更新日期:2020-02-25
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