Hierarchical construction of MoSe2 nanoparticles anchored on N-doped porous carbon nanocages with Mo-C bonding for enhanced potassium-ion storage

Abstract

Molybdenum selenide (MoSe2) is considered as a promising anode material for potassium ion batteries (PIBs) due to its high theoretical capacity and large interlayer spacing. However, the low intrinsic conductivity and large volume expansion impede its practical application. Herein, hierarchical nanostructure of MoSe2 nanoparticles tightly anchored on hollow porous nitrogen-doped carbon nanocages (MoSe2/NCC) is constructed as an anode material for PIBs. Nitrogen-doped carbon nanocages not only improve the conductivity, provide more active sites, and alleviate the volume expansion during K+ insertion and desertion, but also serve as a nucleation substrate for suppressing the agglomeration of MoSe2 nanoparticles. Importantly, the structural stability and electron/ion transfer kinetics are significantly enhanced by strong interfacial coupling between MoSe2 and carbon via the formation of Mo-C bonding. Consequently, MoSe2/NCC electrode exhibits a reversible capacity of 321 mA h g−1 at 0.1 A g−1, excellent cycling stability with a retention of 323 mA h g−1 after 80 cycles, and rate capability of 173 mA h g−1 at 5 A g−1. In addition, the storage mechanism and transfer kinetics of potassium ions during the charging and discharging process are investigated. This work paves the ideas for the design of novel anode materials for high-rate and stable PIBs.