Tungsten‐Doped Nanocrystalline V6O13 Nanoparticles as Low‐Cost and High‐Performance Electrodes for Energy Storage Devices

Vanadium oxide (VO x ) nanomaterials are promising candidates for energy storage devices, such as lithium‐ and sodium‐ion batteries and supercapacitors, in which many complicated structural designs and composite strategies are applied to harness the high theoretical capacity of these materials. Herein, a simple yet effective method to achieve improved performance of electrodes via tungsten doping in a green hydrothermal reaction is demonstrated. The evolution of three VO x phases (V 2 O 5 , VO 2 , and V 6 O 13 ) during the synthesis of the VO x nanostructures is revealed by the systematic investigation of the reaction products. The dopants are critical for the formation of nanocrystalline structures. The as‐fabricated VO x is tested for lithium‐ion batteries, which shows that tungsten doping significantly improves the battery performance, including initial discharge capacity of the VO x (doped VO x = 615.2 ± 41.6 mAh g –1 , undoped VO x = 377.9 ± 72.8 mAh g –1 , and precursor V 2 O 5 = 393.4 ± 74.0 mAh g –1 ), cycle stability, and rate performance. This research provides important insights into the understanding of the dopant‐induced phase tuning of VO x nanostructures for energy storage–related applications.