Inhibiting dissolution strategy achieving high-performance sodium titanium phosphate hybrid anode in seawater-based dual-ion battery

Aqueous sodium-ion batteries hold practical promise for large-scale energy storage; however, the energy density and lifespan are constrained by the decomposition of anode materials. To address this issue, a Bi-coating is applied to inhibit the localized enrichment of OH– near the NTP surface, effectively curbing its dissolution. Moreover, the Bi-coating on the hybrid anode ensures a higher capacity compared to other NTP-based anodes, attributed to the anion-cation relay mechanism. This study lays the foundation for a potential approach to developing long-lifespan NTP-based anodes and SIBs. [Display omitted] •The OH– hindered Bi-coating was firstly constructed by elaborate design.•The designed Bi-coating can significantly enhance the stability of NTP.•The NTP-based hybrid anode sets a new record for the capacity. Aqueous sodium-ion batteries (ASIBs) show great promise as candidates for large-scale energy storage. However, the potential of ASIB is impeded by the limited availability of suitable anode types and the occurrence of dissolution side reactions linked to hydrogen evolution. In this study, we addressed these challenges by developing a Bi-coating modified anode based on a sodium titanium phosphate (NTP)-carbon fibers (CFs) hybrid electrode (NTP-CFs/Bi). The Bi-coating effectively mitigates the localized enrichment of hydroxyl anion (OH–) near the NTP surface, thus addressing the dissolution issue. Notably, the Bi-coating not only restricts the local abundance of OH– to inhibit dissolution but also ensures a higher capacity compared with other NTP-based anodes. Consequently, the NTP-CFs/Bi anode demonstrates an impressive specific capacity of 216.8 mAh/g at 0.2 mV/s and maintains a 90.7 % capacity retention after 1000 cycles at 6.3 A/g. This achievement sets a new capacity record among NTP-based anodes for sodium storage. Furthermore, when paired with a cathode composed of hydroxy nickel oxide directly grown on Ni foam, we assembled a seawater-based cell exhibiting high energy and power densities, surpassing the most recently reported ASIBs. This groundbreaking work lays the foundation for a potential method to develop long-life NTP-based anodes.