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

Owing 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.

Automated summary

The heterogeneous MoSe2/N-doped carbon nanoarrays demonstrate excellent performance as KIBs anode materials, with enhanced K-ion diffusion and improved electrochemical reversibility, resulting in unprecedented K-ion storage performance with high capacity retention over cycles.