Boosting potassium-storage performance via confining highly dispersed molybdenum dioxide nanoparticles within N-doped porous carbon nano-octahedrons.

The development of durable and stable metal oxide anodes for potassium ion batteries (PIBs) has been hampered by poor electrochemical performance and ambiguous reaction mechanisms. Herein, we design and fabricate molybdenum dioxide (MoO)@N-doped porous carbon (NPC) nano-octahedrons through metal-organic frameworks derived strategy for PIBs with MoO nanoparticles confined within NPC nano-octahedrons. Benefiting from the synergistic effect of nanoparticle level of MoO and N-doped carbon porous nano-octahedrons, the MoO@NPC electrode exhibits superior electron/ion transport kinetics, excellent structural integrity, and impressive potassium-ion storage performance with enhanced cyclic stability and high-rate capability. The density functional theory calculations and experiment test proved that MoO@NPC has a higher affinity of potassium and higher conductivity than MoO and N-doped carbon electrodes. Kinetics analysis revealed that surface pseudocapacitive contributions are greatly enhanced for MoO@NPC nano-octahedrons. In-situ and ex-situ analysis confirmed an intercalation reaction mechanism of MoO@NPC for potassium ion storage. Furthermore, the assembled MoO@NPC//perylenetetracarboxylic dianhydride (PTCDA) full cell exhibits good cycling stability with 72.6 mAh g retained at 100 mA g over 200 cycles. Therefore, this work present here not only evidences an effective and viable structural engineering strategy for enhancing the electrochemical behavior of MoO material in PIBs, but also gives a comprehensive insight of kinetic and mechanism for potassium ion interaction with metal oxide.