Key Laboratory of Synthesis and Natural Functional Molecular Chemistry (Ministry of Education), College of Chemistry & Materials Science, Northwest University , Xi'an, Shaanxi, 710069, China.
Nano Lett. 2013 Sep 11;13(9):4206-11. doi: 10.1021/nl4018868. Epub 2013 Aug 7.
To date, most of the research on electrodes for energy storage has been focused on the active material itself. It is clear that investigating isolated active materials is no longer sufficient to solve all kinds of technological challenges for the development of modern battery infrastructure. From the interface chemistry point of view, a system-level strategy of designing polydopamine coated reduced graphene oxide/sulfur composite cathodes aimed at enhancing cyclic performance was reported in this work. As a soft buffer layer, the polydopamine shell was used to accommodate the volume expansion of S and avoid the leakage of polysulfide during cycling. A cross-link reaction between polydopamine buffer and poly(acrylic acid) binder was further designed to improve the strength of the entire electrode. As a result, the electrode demonstrated excellent cyclic performance with a discharge capacity of 728 mAh/g after 500 cycles at the current density of 0.5 A/g (a very small capacity loss of 0.41 mAh/g per cycle). Most importantly, 530 mAh/g was obtained even at a higher current density of 1 A/g after 800 cycles. Our results indicate the importance of chemically designing interfaces in the whole electrode system on achieving improved performance of electrodes of rechargeable lithium ion batteries.
迄今为止，大多数储能电极的研究都集中在活性材料本身。显然，仅研究孤立的活性材料已经不足以解决现代电池基础设施发展所面临的各种技术挑战。从界面化学的角度来看，本工作报道了一种系统级策略，即设计聚多巴胺包覆还原氧化石墨烯/硫复合正极，以提高循环性能。聚多巴胺壳层作为软缓冲层，用于容纳 S 的体积膨胀，并在循环过程中避免多硫化物的泄漏。进一步设计了聚多巴胺缓冲层和聚丙烯酸粘结剂之间的交联反应，以提高整个电极的强度。结果，该电极在 0.5 A/g 的电流密度下循环 500 次后，具有 728 mAh/g 的出色循环性能（每循环的容量损失非常小，为 0.41 mAh/g）。最重要的是，在 800 次循环后，即使在更高的电流密度 1 A/g 下，仍可获得 530 mAh/g 的容量。我们的研究结果表明，在整个电极系统中进行化学界面设计对于提高可充电锂离子电池电极的性能非常重要。
