Electrolyte plays an important role in the success of rechargeable batteries. Identification of appropriate electrolyte materials for sodium-based batteries is an active research area today. Using molecular dynamics method, we simulate a widely studied electrolyte for sodium-ion batteries (SIBs): NaPF₆ salt in ethylene carbonate solvent. The roles of temperature and salt concentration on the structural and dynamic properties of the electrolyte are studied. Temperature and salt concentration affect the molecular structure of the solution. The electrolyte tends to form contact-ion-pairs and multi-ion aggregates at higher temperature and concentration. An in-depth understanding of the effect of temperature and concentration on various properties of the electrolyte that define the rate and safety characteristics of the battery is required to rationally guide the design of electrolytes for SIBs.