NaV ₃ O ₈ /poly(3,4‐ethylenedioxythiophene) composites as high‐rate and long‐lifespan cathode materials for reversible sodium storage

Abstract

Abstract Sodium‐ion batteries have received a surge of interests for the alternatives to lithium‐ion batteries due to their abundant reserves and low cost. The quest of reliable and high‐performance cathode materials is crucial to future Na storage technologies. Herein, poly(3,4‐ethylenedioxythiophene) (PEDOT) was successfully introduced to NaV 3 O 8 via in situ oxidation polymerization, which can effectively enhance electron conductivity and ionic diffusion of NaV 3 O 8 material. As a result, these NaV 3 O 8 @PEDOT composites exhibit a significantly improved electrochemical performance including cycle stability and rate performance. In particular, NaV 3 O 8 @20 wt% PEDOT composite demonstrates better dispersibility and lower charge transfer resistance compared with bare NaV 3 O 8 , which delivers the first discharge capacity of 142 mAh·g −1 and holds about 128.7 mAh·g −1 after 300 cycles at a current density of 120 mA·g −1 . Even at a high current density of 300 mA·g −1 , a high reversible capacity of 99.6 mAh·g −1 is revealed. All these consequences suggest that NaV 3 O 8 @20 wt% PEDOT composite may be a promising candidate to serve as a high‐rate and long‐lifespan cathode material for sodium‐ion batteries.