Nano-sized MoO2 spheres interspersed three-dimensional porous carbon composite as advanced anode for reversible sodium/potassium ion storage

Recently, MoO 2 has been widely studied as an anode material owing to its high theoretical capacity and stability. In this study, nano-sized MoO 2 is successfully fabricated on three-dimensional porous carbon (3DPC) using a simple hydrothermal method followed by calcination . The composite exhibits higher surface area (171.6 m 2  g −1 ) than that of bulk MoO 2 (81.4 m 2  g −1 ). For the first time, the novel MoO 2 /3DPC composite is tested in both sodium and potassium ion batteries . The MoO 2 /3DPC composite exhibits improved electrochemical performance than that of bulk MoO 2 powder. In Na + half cells, the specific charge capacity in the first cycle of the MoO 2 /3DPC composite at 0.1 A g −1 is ∼463 mAh g −1 and a reversible capacity of ∼367 mAh g −1 can be maintained after 200 cycles. In K + half cells, the initial charge capacity is ∼350 mAh g −1 at 0.05 A g −1 . In addition, a reversible charge capacity of as high as 213 mAh g −1 can be maintained after 200 cycles. The synergistic effect of 3DPC and nano-sized MoO 2 improves the electrochemical performance. The unique 3D structure of porous carbon can increase the electrical conductivity and alleviate the absolute stress/strain. Results demonstrate that the MoO 2 /3DPC composite is one of the promising candidates for Na + /K + storage.