Walnut-like MoO ₂ with interconnected skeleton and opened muti-channel for fast sodium storage

Abstract Molybdenum dioxide (MoO ₂ ) has attracted lots of theoretical interest as an anode material for sodium ion batteries (SIBs) due to its high theoretical capacity (836 mA h g ⁻¹ ) and metallic electrical conductivity (1.9 × 10 ² S cm ⁻¹ ). The insertion reaction, forming Na _0.98 MoO ₂ and the reversible conversion reaction, forming Mo and Na ₂ O from Na _0.98 MoO ₂ contribute capacities of 209 and 627 mA h g ⁻¹ , respectively, the latter occupies 75% of the totally theoretical capacity. However, intrinsic slow kinetics in bulk MoO ₂ severely restricts the redox conversion reaction. In the present work, a walnut-like MoO ₂ architecture (W-MoO ₂ ) with opened multi-channel and interconnected skeleton was prepared in a tube furnace, providing an interconnected ion/electron dual-pathway, which effectively facilitates Na ⁺ diffusion and reduces the internal resistance of the cells. The W-MoO ₂ anode demonstrates an enhanced reversible sodium storage capacity of 354.7 mA h g ⁻¹ at 0.5 A g ⁻¹ .