Organically modified NbSe2 as cathode material for magnesium-lithium hybrid batteries

Rechargeable magnesium-lithium hybrid batteries (MLHBs) are promising for energy storage applications due to their high volumetric energy density, enhanced safety, and reliable performance. However, the advancement of MLHBs has been impeded by the low median discharge voltage and insufficient cycle life of cathode materials. In this work, NbSe2 pre-intercalated with PY14+ ions is employed as the cathode for MLHBs, delivering a median discharge voltage as high as 1.30 V. The intercalation of PY14+ effectively expands the interlayer spacing of the material, which provides wider diffusion channels for ion transport and reduces the migration barrier. This structural modification significantly enhances the rate capability of the material, enabling a reversible capacity of 58.71 mAh g−1 even at a high current density of 2000 mA g−1. Simultaneously, PY14+ ions act as structural pillars, mitigating the collapse of the layered structure during cycling and thereby improving the cycling stability, with a capacity retention of 61.65% after 1000 cycles at 500 mA g−1. Kinetic analyses and ex situ characterization confirm an increased contribution from the diffusion-controlled process and a highly reversible conversion reaction mechanism in the PY14+-intercalated NbSe2 cathode. This study provides valuable insights for developing high-performance cathodes for MLHBs.