One‐Step Synthesis of 2‐Ethylhexylamine Pillared Vanadium Disulfide Nanoflowers with Ultralarge Interlayer Spacing for High‐Performance Magnesium Storage

Abstract

Abstract Rechargeable magnesium batteries (RMBs) are attractive candidates for large‐scale energy storage owing to the high theoretical specific capacity, rich earth abundance, and good safety characteristics. However, the development of desirable cathode materials for RMBs is constrained by the high polarity and slow intercalation kinetics of Mg 2+ ions. Herein, it is demonstrated that 2‐ethylhexylamine pillared vanadium disulfide nanoflowers (expanded VS 2 ) with enlarged interlayer distances exhibit greatly boosted electrochemical performance as a cathode material in RMBs. Through a one‐step solution‐phase synthesis and in situ 2‐ethylhexylamine intercalation process, VS 2 nanoflowers with ultralarge interlayer spacing are prepared. A series of ex situ characterizations verify that the cathode of expanded VS 2 nanoflowers undergoes a reversible intercalation reaction mechanism, followed by a conversion reaction mechanism. Electrochemical kinetics analysis reveal a relatively fast Mg‐ion diffusivity of expanded VS 2 nanoflowers in the order of 10 −11 –10 −12 cm 2 s −1 , and the pseudocapacitive contribution is up to 64% for the total capacity at 1 mV s −1 . The expanded VS 2 nanoflowers show highly reversible discharge capacity (245 mAh g −1 at 100 mA g −1 ), good rate capability (103 mAh g −1 at 2000 mA g −1 ), and stable cycling performance (90 mAh g −1 after 600 cycles at 1000 mA g −1 ).