Densely Populated Bismuth Nanosphere Semi-Embedded Carbon Felt for Ultrahigh-Rate and Stable Vanadium Redox Flow Batteries.
Densely Populated Bismuth Nanosphere Semi-Embedded Carbon Felt for Ultrahigh-Rate and Stable Vanadium Redox Flow Batteries.
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DOI：
10.1002/smll.201907333
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发表时间：
2020-08
期刊：
影响因子：
13.3
通讯作者：
Xuelong Zhou;Xiangyang Zhang;Lanlan Mo;Xuechang Zhou;Qixing Wu
中科院分区：
文献类型：
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作者：
Xuelong Zhou;Xiangyang Zhang;Lanlan Mo;Xuechang Zhou;Qixing Wu
高活性电催化剂在多孔基底中的精细空间排列和固定对于钒氧化还原液流电池能够高倍率充电/放电和稳定运行至关重要。本文设计并制备了一种铋纳米球/碳毡，通过碳热还原纳米结构的氧化铋。铋纳米球的尺寸约为25 nm，以高度分散的方式分布在碳纤维表面，其密度可达500 pcs µm-2，提供了丰富的活性位点。此外，在碳热反应过程中自发形成具有强界面Bi/C化学键的独特铋纳米球半嵌入式碳纤维结构，在流动电解质下提供优异的机械稳定性。结果表明，铋纳米球半包埋碳毡能有效地促进V（II）/V（III）氧化还原反应，具有一定的催化活性。当电流密度达到480 mA cm-2时，电池的能量效率为77.1 ± 0.2%，电解液利用率为57.2 ± 0.2%，明显高于电沉积法制备的铋纳米颗粒/碳毡电池的能量效率（62.6 ± 0.1%，23.6 ± 0.2%）。此外，具有本电极的电池在1000次循环后表现出98.2%的稳定能效保持率。
The elaborate spatial arrangement and immobilization of highly active electrocatalysts inside porous substrates are crucial for vanadium redox flow batteries capable of high-rate charging/discharging and stable operation. Herein, a type of bismuth nanosphere/carbon felt is devised and fabricated via the carbothermic reduction of nanostructured bismuth oxides. The bismuth nanospheres with sizes of ≈25 nm are distributed on carbon fiber surfaces in a highly dispersed manner and its density reaches up to ≈500 pcs µm-2 , providing abundant active sites. Besides, a unique bismuth nanosphere semi-embedded carbon fiber structure with strong interfacial BiC chemical bonding is spontaneously formed during carbothermic reactions, offering an excellent mechanical stability under flowing electrolytes. It shows that the bismuth nanosphere semi-embedded carbon felt can effectively promote V(II)/V(III) redox reactions with appreciable catalytic activity. The battery with the present electrode sustains an energy efficiency of 77.1 ± 0.2% and an electrolyte utilization of 57.2 ± 0.2% even when a current density up to 480 mA cm-2 is applied, which are remarkably higher than those of batteries with the bismuth nanoparticle/carbon felt synthesized by the electrodeposition method (62.6 ± 0.1%, 23.6 ± 0.2%). Further, the battery with the present electrode demonstrates a stable energy efficiency retention of 98.2% after 1000 cycles.