Synchronous regulation of Schottky/p-n dual junction in Prussian blue-derived Janus heterostructures: A path to ultrafast long life potassium ion batteries

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 474; p. 145992
• Main Authors: Mai, Shou-Shan, Hsiao, Kai-Yuan, Yang, Yi-Chun, Lu, Ying-Rui, Lu, Ming-Yen, Hsieh, Yi-Yen, Chang, Che-Bin, Tuan, Hsing-Yu
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.10.2023
• Subjects: Graphite layer; Janus heterostructure; P-n junction; Potassium ion battery; Schottky junction; Schottky junction; P-n junction; Graphite layer; Potassium ion battery; Janus heterostructure
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2023.145992

[Display omitted] •A Janus heterostructure, namely CoSe2-FeSe2/graphite/N-doped carbon.•(CFS//g@NC) was prepared.•CFS//g@NC with dual heterojunction (p-n and Schottky junction) was used as a potassium ion battery anode.•DFT calculations reveal that the diffusion barrier of K ions on CFS//g@NC is half that on CoSe2 or FeSe2.•CFS//g@NC delivers a capacity of 200 mA h g−1 at a high rate of 10 A/g.•CFS//g@NC exhibits excellent cycling stability of over 2500 cycles at 0.5 A/g. Practical applications of conversion-type metal selenide electrodes in potassium ion batteries (PIBs) encounter multiple challenges, such as particle aggregation, the shuttle effect, and pulverization during cycling. We design a Janus heterostructure, namely CoSe2-FeSe2/graphite/N-doped carbon (CFS//g@NC), with dual heterojunctions (p-n and Schottky junction), which generates the synergistic effect to enhance interface charge storage and improve electrode structure integrity. When the Janus heterostructure is used as a PIB anode, it demonstrates high-rate performance up to 10 A/g, offering a capacity of 200 mA h g−1 and excellent cycling stability of over 2500 cycles at 0.5 A/g. According to the density functional theory (DFT) calculations, the diffusion barrier of K ions on CFS//g@NC is two times lower than that on CoSe2 or FeSe2. The distribution of n-type and p-type semiconductors in the Janus particles has been confirmed by quantitative assessment through dark-field electron microscopy. In addition to the p-n junction crossing two semiconductor interfaces, the Schottky junction between the graphite layer derived from Prussian blue analogues (PBA) and the semiconductor also creates a built-in electric field, thus enhancing ion/electron transport and increasing the diffusion of potassium ions. This work provides new insights into the architectural strategy of multi-layer heterointerfaces and offers a promising new pathway for anode design in PIBs.