溶解
吸附
阴极
氧化还原
碳纤维
金属
电池(电)
材料科学
电极
化学
硫黄
无机化学
锂(药物)
氧化物
化学工程
电化学
有机化学
物理化学
复合材料
功率(物理)
内分泌学
工程类
物理
复合数
医学
量子力学
作者
Quanquan Pang,Dipan Kundu,Marine Cuisinier,Linda F. Nazar
摘要
The lithium-sulphur battery relies on the reversible conversion between sulphur and Li2S and is highly appealing for energy storage owing to its low cost and high energy density. Porous carbons are typically used as sulfur hosts, but they do not adsorb the hydrophilic polysulphide intermediates or adhere well to Li2S, resulting in pronounced capacity fading. Here we report a different strategy based on an inherently polar, high surface area metallic oxide cathode host and show that it mitigates polysulphide dissolution by forming an excellent interface with Li2S. Complementary physical and electrochemical probes demonstrate strong polysulphide/Li2S binding with this ‘sulphiphilic’ host and provide experimental evidence for surface-mediated redox chemistry. In a lithium-sulphur cell, Ti4O7/S cathodes provide a discharge capacity of 1,070 mAh g−1 at intermediate rates and a doubling in capacity retention with respect to a typical conductive carbon electrode, at practical sulphur mass fractions up to 70 wt%. Stable cycling performance is demonstrated at high rates over 500 cycles. In lithium-sulfur batteries, many porous conductive carbon materials are proposed to confine soluble polysulfides, but the efficiency is generally low. Here, the authors use a Magnéli phase of titanium oxide as the cathode host and electron conduit, which binds the lithium (poly)sulfides well, leading to excellent battery performance.
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