Zhao Menglong, Lu Yang, Yang Ya, Zhang Mengjie, Yue Zhenjie, Zhang Ning, Peng Tao, Liu Xianming, Luo Yongsong
Henan Joint International Research Laboratory of New Energy Storage Technology, Key Laboratory of Microelectronics and Energy of Henan Province, School of Physics and Electronic Engineering, Xinyang Normal University, Xinyang 464000, P. R. China.
Nanoscale. 2021 Aug 14;13(30):13085-13094. doi: 10.1039/d1nr03763c. Epub 2021 Jul 23.
The commercial application of lithium-sulfur (Li-S) batteries is obstructed by the inherent dissolution/shuttling of lithium polysulfides (LiPSs) in a sluggish redox reaction. Here, a heterophase VO-VN yolk-shell nanosphere encapsulated by a nitrogen-doped carbon layer has been designed to address the problems of the short cycle life and rapid capacity decay of Li-S batteries synchronously. The structural merits comprise efficient polysulfide anchoring (VO), rapid electron transfer (VN) and a reinforced frame (N-doped carbon). The assembled cathode based on the VO-VN@NC sulfur host delivered a high initial capacity of 1352 mA h g at 0.1C with excellent rate performance (797 mA h g at 2C) and favorable cycle stability with a low capacity-decay rate of only 0.038% per cycle over 800 cycles at 1C. Even with a high sulfur loading of 3.95 mg cm, an initial capacity of 954 mA h g at 0.2C could be achieved, along with a good capacity retention of 75.1% after 150 cycles. Density functional theory computations demonstrated the crucial role of the VO-VN@NC heterostructure in the trapping-diffusion-conversion of polysulfides. This multi-functional cathode is very promising in realizing practically usable Li-S batteries owing to the simple process and the prominent rate and cyclic performances.
锂硫（Li-S）电池的商业应用受到多硫化锂（LiPSs）在缓慢氧化还原反应中固有溶解/穿梭的阻碍。在此，设计了一种由氮掺杂碳层包裹的异相VO-VN蛋黄壳纳米球，以同步解决Li-S电池循环寿命短和容量快速衰减的问题。其结构优点包括高效的多硫化物锚定（VO）、快速的电子转移（VN）和增强的框架（氮掺杂碳）。基于VO-VN@NC硫主体组装的阴极在0.1C时具有1352 mA h g的高初始容量，具有优异的倍率性能（2C时为797 mA h g），并且在1C下800次循环中具有良好的循环稳定性，容量衰减率仅为每循环0.038%。即使硫负载量高达3.95 mg cm，在0.2C时仍可实现954 mA h g的初始容量，并且在150次循环后具有75.1%的良好容量保持率。密度泛函理论计算证明了VO-VN@NC异质结构在多硫化物的捕获-扩散-转化中的关键作用。由于工艺简单以及突出的倍率和循环性能，这种多功能阴极在实现实际可用的Li-S电池方面非常有前景。
