Song Lili, Zhang Shilin, Duan Liping, Li Renke, Xu Yifan, Liao Jiaying, Sun Liang, Zhou Xiaosi, Guo Zaiping
School of Chemistry and Materials Science, Nanjing Normal University, Nanjing, 210023, China.
School of Chemical Engineering, University of Adelaide, Adelaide, South Australia, 5000, Australia.
Angew Chem Int Ed Engl. 2024 Jul 8;63(28):e202405648. doi: 10.1002/anie.202405648. Epub 2024 May 28.
The interfacial electric field (IEF) in the heterostructure can accelerate electron transport and ion migration, thereby enhancing the electrochemical performance of potassium-ion batteries (PIBs). Nevertheless, the quantification and modulation of the IEF for high-efficiency PIB anodes currently remains a blank slate. Herein, we achieve for the first time the quantification and tuning of IEF via amorphous carbon-coated undifferentiated cobalt-doped FeSe/FeSe heterostructure (denoted UN-CoFeSe/C) for efficient potassium storage. Co doping can increase the IEF in FeSe/FeSe, thereby improving the electron transport, promoting the potassium adsorption capacity, and lowering the diffusion barrier. As expected, the IEF magnitude in UN-CoFeSe/C is experimentally quantified as 62.84 mV, which is 3.65 times larger than that of amorphous carbon-coated FeSe/FeSe heterostructure (FeSe/C). Benefiting from the strong IEF, UN-CoFeSe/C as a PIB anode exhibits superior rate capability (145.8 mAh g at 10.0 A g) and long cycle lifespan (capacity retention of 95.1 % over 3000 cycles at 1.0 A g). Furthermore, this undifferentiated doping strategy can universally regulate the IEF magnitude in CoSe/CoSe and FeS/FeS heterostructures. This work can provide fundamental insights into the design of advanced PIB electrodes.
异质结构中的界面电场（IEF）可以加速电子传输和离子迁移，从而提高钾离子电池（PIB）的电化学性能。然而，目前用于高效PIB阳极的IEF的量化和调制仍然是一片空白。在此，我们首次通过非晶碳包覆的未分化钴掺杂FeSe/FeSe异质结构（表示为UN-CoFeSe/C）实现了IEF的量化和调节，以实现高效的钾存储。钴掺杂可以增加FeSe/FeSe中的IEF，从而改善电子传输，提高钾吸附能力，并降低扩散势垒。正如预期的那样，UN-CoFeSe/C中的IEF大小通过实验量化为62.84 mV，这是非晶碳包覆的FeSe/FeSe异质结构（FeSe/C）的3.65倍。受益于强大的IEF，UN-CoFeSe/C作为PIB阳极表现出优异的倍率性能（在10.0 A g下为145.8 mAh g）和长循环寿命（在1.0 A g下3000次循环后的容量保持率为95.1%）。此外，这种未分化的掺杂策略可以普遍调节CoSe/CoSe和FeS/FeS异质结构中的IEF大小。这项工作可以为先进PIB电极的设计提供基本见解。
