Sodium vanadate hydrate (NaV 3 O 8 ·1.5H 2 O, NVO) is a promising layered cathode material that offers a high theoretical capacity while delivering exceptional fast-charging performance. However, the long-term cycling performance of NVO at moderate current densities (0.25C to 2C) for practical application is hampered by significant vanadium dissolution, and structural degradation induced by Na + -pillar loss. Herein, a concentrated bisalt electrolyte based on a water-trimethyl phosphate (TMP) mixture is designed to simultaneously suppress vanadium dissolution and Na + interlayer leakage of NVO. The proposed electrolyte consists of 1 m ZnAc 2 and 5 m NaAc in an 80:20 ( v /v) H 2 O/TMP mixture. The failure of NVO cathodes is attributed to vanadium dissolution (induced by active water attack and local pH fluctuations) as well as Na + -pillar loss, as identified through various characterization techniques such as X-ray diffraction and electron microscopy. This failure mechanism can be effectively mitigated by the high abundance of Na + , hydrophilic acetate anions, and TMP molecules in the electrolyte. These components collectively suppress water activity, restrict anodic OH − crossover and proton co-insertion into NVO via hydrogen bond modulation and Zn 2+ solvation structure regulation, and meanwhile preserve the intact nanostructure of NVO cathode. This approach enables Zn||NVO full cells to achieve exceptional cycling stability (∼1.6 mAh cm −2 for 240 cycles at 0.1 A g −1 ), underscoring its practical potential. • A concentrated bisalt electrolyte was designed to stabilize sodium vanadate hydrate • Reducing active H 2 O attack, H + insertion, anodic OH − crossover to NVO and Na + loss • Simultaneously suppressing vanadium dissolution and Na + interlayer leakage of NVO • Achieving stable cycling performance of Zn||NVO cells for 1500 cycles at 0.2 A g −1
Fei et al. (Thu,) studied this question.