Breaking the limitation of sodium-ion storage for nanostructured carbon anode by engineering desolvation barrier with neat electrolytes

In the past, most of the studies monotonously focused on developing electrode materials for sodium ion batteries (SIBs), while the compatibility effects and mechanism of electrolytes with material microstructures on the sodiation behavior are barely involved. Here, we demonstrate the sodium-ion storage behavior of carbon anode in neat ether electrolytes with outstanding ion diffusion kinetics at electrode surface that breaks its innate limitation. Porous nanocarbon with small interlayer spacing but very high surface area exhibits a record high ICE over 91.1% and exceptional rate capability for Na-ion storage in ether-based electrolytes. This is due to the remarkably reduced Na+ desolvation barrier in ether electrolytes (~94.6 meV) that is less than one-third of that in ester electrolytes (~307.8 meV). The strong interaction of Na-ions with ester electrolytes and their decomposition on electrode surface can be suppressed by adopting ether solvents owing to lower Gibbs free energies of solvation and Na+ desolvation energy as revealed by DFT calculations. For electrode materials working with ether electrolytes, a large surface area is critical for better electrochemical performance. This study provides a reliable regulation parameter for tailoring electrolytes with materials that offers promising potential for nanostructured materials toward high-rate rechargeable devices.