Deep eutectic solvent synthesis of a 3D hierarchical porous NaTi2(PO4)3/C as a high-performance anode for sodium-ion batteries

A 3D hierarchical porous NaTi2(PO4)(3)/C was successfully synthesized by using choline chloride/triethanolamine-based deep eutectic solvent (DES), which act as both solvent and template. The as-synthesized sample consisted of carbon-coated nanosized NaTi2(PO4)(3) with abundant macropores. When this sample is used as an anode material for sodium-ion batteries, it exhibits excellent rate capability (116 mAh g(-1) at 5 C and 113 mAh g(-1) at 20 C) and superior long-term cyclic stability (capacity retention of over 99% after 1000 cycles at 5 and 20 C). The improved performance can be ascribed to the high Na+ transport and its high structural stability. The excellent electrochemical results indicate that the prepared 3D hierarchical porous NaTi2(PO4)(3)/C could be used as a promising anodematerial for SIBs. The finding of this work opens a new way to design porous electrode materials by using DESs as structure-directing reagent.