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

NASICON-type NaTi2(PO4)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 [email protected]) is designed with significantly improved electronic conductivity and structural stability. With further regulations in both the dissolved oxygen content and pH values of aqueous Na2SO4 electrolyte, the enhanced reversible capacities and cyclic stability especially at high rates are achieved by effectively alleviating side reactions. As a result, the fabricated [email protected] anode is optimized with a high-rate capability and remarkable long-duration electrochemical stability in the N2-purged aqueous Na2SO4 electrolyte with pH = 8.0. Furthermore, the assembled [email protected]//Na0.44MnO2 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.