Boosting potassium-ion storage in large-diameter carbon nanotubes/MoP hybrid

Potassium-ion batteries (KIBs) as a substitute for lithium ion batteries have attracted tremendous attention in recent years thanks to the cost-effectiveness and abundance of potassium resources. However, the current lack of suitable electrode materials is a major obstacle against the practical application of KIBs. Hence, design and preparation of capable anode materials are critical for the development of KIBs. In this study, a promising electrode based on N, P-codoped large diameter hollow carbon nanotubes decorated with ultrasmall MoP nanoparticles (MoP@NP-HCNTs) were prepared. The hollow carbon nanotubes facilitate the rapid electron and ion transfer, and release the huge volume expansion during discharge/charge. The MoP@NP-HCNT electrode delivers high initial capacity of 485, 482 and 463 mAh g^-1 corresponding to 100, 200 and 1000 mA g^-1, respectively. The discharge specific capacity still maintains 300 mAh g^-1 at 100 mA g^-1 after over 80 cycles. It still shows ultralong cycling stability with a discharge capacity of 255 mAh g^-1 at a high current density of 1000 mA g^-1 after 120 cycles. This study opens up a new routine to develop high reversible capacity and promising electrode materials for KIBs.