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.