Biomass Hyaluronic Acid to Construct High‐Loading Electrode with Fast Na+ Transport Structure for Na3V2(PO4)3 Sodium‐Ion Batteries

Abstract Sodium‐ion batteries (SIBs) are considered a promising candidate in green energy storage due to their considerable abundance. The low mass loading (less than 2.0 mg cm −2 ) of SIBs‐based cathodes cannot meet the energy density on the practical device level, which is mainly restricted by sluggish Na + transport. To the end, a facile and compatible strategy was demonstrated by utilizing hyaluronic acid (HA) binder to achieve fast ion transport and targeted energy density for Na 3 V 2 (PO 4 ) 3 (NVP) cathodes. As a novel functional aqueous binder, HA allowed cathodic materials to organize the unique conductive network. The network‐like electrode structure could buffer volume changes during sodiation/desodiation process and provide bi‐continuous charge transport channels for both Na + and electrons at the interface. HA promoted the formation of the stable solid permeable interface films, protecting the electrochemical stability of the cathode and ensuring its good cycle performance. These functions of HA binder enabled that NVP delivered a reversible discharge capacity of 107.3 mAh g −1 at 0.5 C (1 C=117 mA g −1 ), which showed no sacrifice of electrochemical performances with mass loading increasing from 1.1 to 4.4 mg cm −2 . Even at a high rate of 20 C, NVP‐HA (loading 4.0 mg cm −2 ) could reserve a good capacity of 76.8 mAh g −1 with the retention of 99.3 % after 2000 cycles. This study provides a novel strategy to achieve high energy density for SIBs in large‐scale energy storage.