Natural Vermiculite Enables High‐Performance in Lithium–Sulfur Batteries via Electrical Double Layer Effects
Natural Vermiculite Enables High‐Performance in Lithium–Sulfur Batteries via Electrical Double Layer Effects
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DOI：
10.1002/adfm.201902820
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发表时间：
2019-05
影响因子：
19
通讯作者：
Feixiang Wu;Haifeng Lv;Shuangqiang Chen;S. Lorger;V. Srot;M. Oschatz;P. V. van Aken;Xiaojun Wu
中科院分区：
文献类型：
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作者：
Feixiang Wu;Haifeng Lv;Shuangqiang Chen;S. Lorger;V. Srot;M. Oschatz;P. V. van Aken;Xiaojun Wu
具有潜在高比能量的锂硫电池被视为下一代轻质低成本可充电电池的非常有前途的候选者。然而，硫基阴极遭受多硫化物的溶解，导致穿梭效应。这里，为了限制元素硫和锚多硫化物，使用了一种新型主体，其是一种廉价的天然粘土矿物，即，提出了蛭石。当与常规的碳-硫复合材料相比时，蛭石-硫复合材料提供有希望的倍率性能和好得多的循环稳定性，在C/2和1C下分别在200次循环内显示出1089和1093%的容量保持率，并且在1000次循环内在C/5下显示出1060%的容量保持率。尸检研究，先进的吸附测试，密度泛函理论计算，zeta电位测量结合天然蛭石的固有特性提供了新的机制的见解。蛭石含有天然存在的表面阳离子，这些阳离子表现出强烈的吸附Sn 2 −阴离子的倾向，从而保护它们不被溶解。多余的表面电荷很可能被空间电荷区中多余的Li+所补偿，这有利于电荷转移和局部导电。报告的结果表明，天然粘土矿物是有前途的硫主体，能够通过双电层效应固定硫化物，从而实现锂硫族电池的高性能。
Lithium–sulfur batteries with potentially high specific energy are viewed as very promising candidates for next‐generation lightweight and low‐cost rechargeable batteries. However, sulfur‐based cathodes suffer from dissolution of polysulfides causing shuttle effects. Here, in order to confine elemental sulfur and anchor the polysulfides, a novel host that is an inexpensive natural clay mineral, viz., vermiculite is proposed. When compared to regular carbon–sulfur composites, vermiculite–sulfur composites offer promising rate capability and much better cycling stabilities, displaying capacity retentions of ≈89 and ≈93% within 200 cycles at C/2 and 1 C, respectively, and ≈60 % at C/5 within 1000 cycles. Postmortem studies, advanced adsorption tests, density functional theory calculations, and zeta potential measurements in combination with intrinsic characteristics of the natural vermiculite provide insights into the new mechanism. The vermiculite contains naturally present surface cations which show a strong tendency to adsorb Sn2− anions, hence protecting them from dissolution. The excess surface charge is most probably compensated by excess Li+ in the space charge zones which is beneficial for charge transfer and local conductivity. The reported results show that natural clay‐minerals are promising sulfur hosts being able to fixate sulfides via electrical double layer effects, thus enabling high‐performance in lithium–chalcogen batteries.