Heterogeneous MoSe2/Nitrogen‐Doped‐Carbon Nanoarrays: Engineering Atomic Interface for Potassium‐Ion Storage

Abstract

AbstractOwing to the lower price and higher safety, developing high‐performance K‐ion batteries (KIBs) is of great significance as an alternative to Li‐ion batteries. High‐energy‐density MoSe2 has been identified as a promising anode material for KIBs; however, its electrochemical reversibility remains a big challenge. Herein, heterogenous MoSe2/N‐doped carbon nanoarrays demonstrate a brilliant performance as KIBs anode materials. The as‐formed hetero‐interface weakens the KSe bond of discharged products (K2Se), the length of KSe bond is stretched by 3.9% with an enlargement of 19.2% in angle compared with pure K2Se, greatly promoting the regeneration of MoSe bond during charge. Moreover, the atomically inter‐overlapping feature leads to an expanded MoSe2 interlayer distance of 1.20 nm that enables a much faster K‐ion diffusion. Consequently, this nanoarray delivers an unprecedented K‐ion storage performance, that is, a capacity of 402 mAh g−1 at 0.2 A g−1 over 200 cycles, and a long cycle life over 1000 cycles at 1.0 A g−1 with 307 mAh g−1 capacity retention.