Sodium-based rechargeable batteries are some of the most promising candidates for electric energy storage with abundant sodium reserves, particularly, sodium-based dual-ion batteries (SDIBs) perform advantages in high work voltage (≈5.0 V), high-power density, and potentially low cost. However, irreversible electrolyte decomposition and co-intercalation of solvent molecules at the electrode interface under a high charge state are blocking their development. Herein, a high-salt concentration microenvironment is created and proposed by tailoring the solvation structures of charge carriers including both cations and anions, which maintains highly oxidation-resistant contact ion pairs and ion aggregates and provides a high ion conductivity. The tailored solvation structure makes a great contribution to protecting the graphite cathode from electrolyte oxidation, solvent co-intercalation, and structural degradation by constructing a robust cathode-electrolyte interphase with standout electrochemical stability. Based on this, the SDIBs achieved an excellent high-voltage cycling stability with 81% capacity retention after 10 000 cycles and the battery showed an improved rate performance with 97.4 mAh g