High-entropy two-dimensional metal phosphorus trichalcogenides boost high-performance potassium ion storage devices via electrochemical reconstruction

Abstract

We investigate the influence of configurational entropy on the cycling performance of 2D metal phosphorus trichalcogenides (MPS₃) when utilized as anodes in potassium-ion devices. High yield, two-dimensional high-entropy CoVMnFeZnPS₃ (HEPS₃) with thickness ranging from 6 to 10 nm was synthesized via a vacuum solid-state method. HEPS₃ enables efficient potassium-ion transport and intercalation at the interface of electrodes, thanks to the high-entropy effects arising from the interaction of various metal ions on the K⁺ binding energy. HEPS₃ potassium-ion anodes outperform their medium-entropy (CoMnFePS₃ (ME₃PS₃) and CoMnFeZnPS₃ (ME₄PS₃)), CoFePS₃ (LE₂PS₃), and FePS₃ (LEPS₃) counterparts, exhibiting a high reversible capacity of 524 mAh g⁻¹, impressive high-rate capability up to 10 A g⁻¹, and exceptional cycling stability over 1000 cycles. Our findings indicate that the electrochemical reconstruction of HEPS₃ during cycling is crucial for achieving high-performance potassium-ion batteries. In situ-formed metal alloy layers act as catalysts, offering not only suitable adsorption energy to prevent the shuttle effect but also promoting the complete conversion of polysulfides. Furthermore, cations uniformly dispersed across the 2D plane create a "lattice distortion effect," imparting the structure with high mechanical stability and allowing for even distribution of internal stress generated in the electrode during the K⁺ insertion/extraction process, which in turn suppresses electrode pulverization and prevents the aggregation of MPCh₃ layers. This work proposes a novel strategy for significantly enhancing potassium-ion storage performance through the electrochemical activation of high-entropy layered metal phosphides, thus opening a new horizon of 2D material design principle in energy storage devices.