Intercalation Reaction in Amorphous Layer-Wrapped Ni_0.2Mo_0.8N/Ni₃N Heterostructure Toward Efficient Lithium-Ion Storage

Transition metal nitrides (TMNs) with high specific capacity and electric conductivity have drawn considerable attention as electrode materials of lithium-ion batteries (LIBs). However, the cycling stability of most TMNs is not satisfactory, which was caused by the large volume variation during cycles due to their intrinsic conversion reaction mechanism. Herein, by rational design, a much stable tremella-like Ni0.2Mo0.8N/Ni3N heterostructure with amorphous Ni0.2Mo0.8N wrapped layer has been fabricated. The Ni3N particles worked as pillars to support the Ni0.2Mo0.8N material as well as conductive medium to facilitate ionic and electronic transport. The amorphous layer can relieve the structural stress of Ni0.2Mo0.8N during cycles. Moreover, an exotic intercalation-type reaction mechanism in the ternary nitride Ni0.2Mo0.8N was revealed by a series ex situ and in situ characterization. Profiting from these advantages, the Ni0.2Mo0.8N/Ni3N heterostructure anode displays an outstanding electrochemical performance with a high initial reversible discharge capacity of 1001.6 mA h g-1 at 0.1 A g-1, excellent cycle stability of 695.5 mA h g-1 at 2 A g-1 after 600 cycles, and superior rate capability of 595.3 mA h g-1 at a high current density of 5 A g-1. This work provides a new insight for designing high efficiency LIBs based on intercalation reaction for practical applications.