Boosting sodium-storage behaviors of NASICON-type NaTi2(PO4)3 anode by synergistic modulations in both materials and electrolytes towards aqueous Na-ion batteries.

• Porous single-crystal NTP micro-sized framework coated with conductive carbon nano-layer (NTP@C) is designed. • The carbon coating enhances conductivity of NTP@C, and protects it from O2 erosion serves as a protective phase. • Regulations in both the dissolved O2 content and pH values of aqueous Na2SO4 electrolyte are conducted. • The NTP@C displays superb electrochemical properties in the optimized Na2SO4 electrolyte (N2 purged and pH = 8.0). • The NTP@C based full devices exhibit high energy density and cycling stability with the optimum electrolyte. NASICON-type NaTi 2 (PO 4) 3 (NTP) is one of the most competitive anode materials for aqueous sodium-ion batteries (ASIBs), thanks to its unique three-dimensional open framework structure, high ionic conductivity and good chemical stability. However, the low electrical conductivity of NTP and the oxygen reduction induced side reactions seriously affect its practical applications. To well address the above issues, the synergistic regulation strategy in electrode materials and electrolytes is motivatively put forward. The porous single-crystal NTP micro-sized framework coated with conductive carbon nano-layer (denoted as NTP@C) is designed with significantly improved electronic conductivity and structural stability. With further regulations in both the dissolved oxygen content and pH values of aqueous Na 2 SO 4 electrolyte, the enhanced reversible capacities and cyclic stability especially at high rates are achieved by effectively alleviating side reactions. As a result, the fabricated NTP@C anode is optimized with a high-rate capability and remarkable long-duration electrochemical stability in the N 2 -purged aqueous Na 2 SO 4 electrolyte with pH = 8.0. Furthermore, the assembled NTP@C//Na 0.44 MnO 2 ASIBs exhibit high energy density of ∼40.0 Wh kg‒1 along with excellent cycling stability. More significantly, our work provides an insightful guideline for rational construction of other advanced aqueous rechargeable batteries. Hierarchical porous single-crystal NaTi 2 (PO 4) 3 @C framework is first designed, and exhibits enhanced electrochemical Na+-storage properties in half/full cells with detailed regulation in both the dissolved oxygen content and pH values of electrolytes, when evaluated a competitive anode platform for aqueous sodium-ion batteries. [Display omitted] [ABSTRACT FROM AUTHOR]