Tubular MoO₂ organized by 2D assemblies for fast and durable alkali-ion storage

Multifunctional anode materials with high durability and outstanding rate capability are desirable for alkali-ion storage applications, such as lithium ion batteries (LIBs) and sodium ion batteries (SIBs). The present study illustrates a tubular nanoarchitecture composed of ultra-fine MoO₂ nanodomains embedded in hierarchical carbon nanosheets by sol-gel processing and post-annealing. The metallic characteristics and small crystallites of MoO₂ not only favor ionic/electronic transport, but also shorten the diffusion length. Hierarchical arrangement of nanosheets and tubular architecture offer sufficient electrode/electrolyte contact and excellent strain-accommodation associated with Li/Na-intercalation. Electrochemical measurements show that hierarchical tubular MoO₂ enable the rapid, reversible, and durable storage of Li/Na-ions. A capacity retention of 89% and 96% is retained at a high rate of 10 A g⁻¹ over 10 000 cycles for LIBs and SIBs, respectively. The greatly enhanced Li/Na ion storage capacity is attributed to the significant pseudocapacitance contributions up to approximately 80% and 95% at 2 mV s⁻¹ for LIBs and SIBs, respectively. These results not only hold prospects for the multifunctional fabrication of durable energy storage devices, but also demonstrate the potential applications of metallic MoO₂ for next-generation clean energy strategies.