Rich oxygen vacancies promotes MoO2/N-doped carbon nanoribbons for high-performance sodium/potassium-ion batteries

The natural abundance and potential cost benefits of sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) make them increasingly appealing as viable substitutes to lithium-ion batteries (LIBs). Nonetheless, the progress of PIBs and SIBs is significantly hindered by the limited poor rate capability and mediocre cycling durability attributed to the huger ionic radius of K+ and Na+ in comparison to Li+. Herein, MoO2/N-doped carbon nanoribbons with rich oxygen vacancies (OVs) have been prepared via hydrothermal method followed by thermal annealing in Ar atmosphere. The composite nanoribbons, as novel anode materials, demonstrate excellent electrochemical performance with a specific capacity of 132.6 mAh g- 1 at 5 A g- 1 for SIBs and 130.2 mAh g- 1 at 1 A g- 1 for PIBs, along with a high Coulombic efficiency of approximately 100% over 2000 cycles for SIBs and 10,000 cycles for PIBs. The highly conductive N-doped carbon significantly facilitates electron transfer, effectively suppress volume expansion, and increase additional sodium and potassium storage sites. A built-in electric field at heterojunction interface is beneficial for Na/K ions diffusion across the interface. Novelty, the rich OVs in MoO2 lattices could induce built-in electric field around localized oxygen-vacancies, accelerating the migration of Na/K ions based on built-in electric field (BIEF) and percolation-channel model.