Lin Haojian, Shi Haodong, Wang Zhen, Mu Yuewen, Li Sidian, Zhao Jijun, Guo Jingwei, Yang Bing, Wu Zhong-Shuai, Liu Fei
State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Province Key Laboratory of Display Material and Technology, and School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, China.
State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
ACS Nano. 2021 Nov 23;15(11):17327-17336. doi: 10.1021/acsnano.1c04961. Epub 2021 Sep 22.
Two-dimensional (2D) borophene has attracted tremendous interest due to its fascinating properties, which have potential applications in catalysts, energy storage devices, and high-speed transistors. In the past few years, borophene was theoretically predicted as an ideal electrode material for lithium-sulfur (Li-S) batteries because of its low-density, metallic conductivity, high Li-ion surface mobility, and strong interface bonding energy to polysulfide. But until now, borophene-based Li-S batteries have not yet been achieved in experiments due to the absence of a large-scale synthetic method of freestanding borophene nanostructures with a high enough structural stability, conductivity, and uniformity. Herein, we developed a low-temperature liquid exfoliation (LTLE) method to synthesize freestanding few-layer β-borophene single-crystalline sheets with a symmetry in tens of milligrams. The as-synthesized 2D sheets were used as the polysulfide immobilizers and electrocatalysts of Li-S batteries. The resulting borophene-based Li-S battery delivered an extralarge areal capacity of 5.2 mAh cm at a high sulfur loading of 7.8 mg cm, an excellent rate performance of 8 C (@721 mAh g), and an ultralow capacity fading rate of 0.039% in 1000 cycles, outperforming commercial Li-ion batteries and many other 2D material-based Li-S batteries. Based on the density functional theory model, the excellent electrochemical performances of the borophene-based Li-S batteries should originate from the enormous enhancement of β-borophene sheets for both the surface migration of the Li-ions and the adsorption energy of LiS clusters. Our results thus demonstrate a great potential for scalable production of freestanding β-borophene single-crystalline sheets in future high-performance Li-S batteries.
二维（2D）硼烯因其迷人的特性而引起了极大的关注，这些特性在催化剂、储能装置和高速晶体管方面具有潜在应用。在过去几年中，硼烯在理论上被预测为锂硫（Li-S）电池的理想电极材料，因为它具有低密度、金属导电性、高锂离子表面迁移率以及与多硫化物的强界面结合能。但直到现在，由于缺乏具有足够高结构稳定性、导电性和均匀性的独立硼烯纳米结构的大规模合成方法，基于硼烯的Li-S电池尚未在实验中实现。在此，我们开发了一种低温液相剥离（LTLE）方法，以合成数十毫克具有对称性的独立少层β-硼烯单晶片。所合成的二维片材用作Li-S电池的多硫化物固定剂和电催化剂。由此得到的基于硼烯的Li-S电池在7.8 mg cm的高硫负载下具有5.2 mAh cm的超大面积容量、8 C（@721 mAh g）的优异倍率性能以及在1000次循环中0.039%的超低容量衰减率，优于商业锂离子电池和许多其他基于二维材料的Li-S电池。基于密度泛函理论模型，基于硼烯的Li-S电池的优异电化学性能应源于β-硼烯片材对锂离子表面迁移和LiS簇吸附能的极大增强。因此，我们的结果表明了在未来高性能Li-S电池中可扩展生产独立β-硼烯单晶片的巨大潜力。
