Fast Li+ diffusion in interlayer-expanded vanadium disulfide nanosheets for Li+/Mg2+ hybrid-ion batteries

Abstract

Li⁺/Mg²⁺ hybrid-ion batteries (LMIBs) have attracted intensive attention because they can circumvent some serious drawbacks of Li- and Mg-rechargeable batteries. In this work, a novel LMIB was proposed that uses a VS₂ nanosheet-based cathode and an all-phenyl complex + LiCl/tetrahydrofuran hybrid electrolyte. Combined spectroscopic analysis and theoretical simulations revealed that (phenyl)₂Mg and tetrahydrofuran inserted into the nanosheets at an early battery-cycling stage. The interlayer spacing of VS₂ was expanded from 5.78 to 8.76 Å by the inserted organic species, which significantly reduced the diffusion barrier of Li⁺. As a result, the LMIBs showed remarkable battery performance with a large discharge capacity (181 mA h g⁻¹ at 50 mA g⁻¹), high rate capability (93 mA h g⁻¹ at 5 A g⁻¹), and long cycle stability (0.04% capacity fading per cycle in 500 cycles).