NiSe2/CoSe2 heterostructure nanoparticles anchoring on graphene for enhanced Li-ions storage

Abstract

Selenide anodes have been extensively studied due to their exceptional electrochemical performance in lithium-ion batteries (LIBs). However, selenides suffer from inadequate specific capacity and high mechanical stress/strain resulting from significant volume changes during cycling. This leads to a rapid reduction in capacity and reversibility, which limits their practical application. Nanoscale bimetallic heterostructure selenides can effectively reduce the lattice vibration induced by lithiation/delithiation and improve the lithium storage capacity and cycle life. This study describes the preparation of NiSe2 and CoSe2 nanoparticles anchored on graphene (NiSe2/CoSe2/Graphene) using freeze-drying and thermal selenization methods. The graphene, selenide particles, and electric field between heterostructure interfaces significantly enhance electrical conductivity, provide active species storage sites, and improve lithium-ion adsorption ability, resulting in high storage capacity and excellent cycling stability. The NiSe2/CoSe2/Graphene composite exhibited a specific capacity of 929.6 mAh g−1 after 320 cycles at a current density of 100 mA g−1. Even at a high current density of 1000 mA g−1, the composite was stably cycled for 1250 cycles with a continuous increase in specific capacity. This study provides valuable insights into the use of bimetallic selenides for improved lithium storage.