Realizing a 3C Fast‐Charging Practical Sodium Pouch Cell

Sodium‐ion batteries (SIBs), endowed with relatively small Stokes radius and low desolvation energy for Na+, are reckoned as a promising candidate for fast‐charging endeavors. However, the C‐rate charging capability of practical energy‐dense sodium‐ion pouch cells is currently limited to ≤1C, due to the high propensity for detrimental metallic Na plating on the hard carbon (HC) anode at elevated rates. Here, an ampere‐hour‐level sodium‐ion pouch cell capable of 3C charging is successfully developed via phosphorus (P)‐sulfur (S) interphase chemistry. By rational electrolyte regulation, desired P‐S constituents, namely, Na3PO4 and Na2SO4, are generated in the solid‐electrolyte interphase with favorable Na+ interface kinetics. Specifically, Na+ desolvation energy barrier has been greatly lowered by the weak ion‐solvent coordination near the inner Helmholtz plane on Na3PO4 interphase, while Na2SO4 expedites charge carrier mobility due to its intrinsically high ionic conductivity. Consequently, an energy‐dense (126 Wh kg‐1) O3‐Na(Ni1/3Fe1/3Mn1/3)O2||HC pouch cell capable of 3C charging (100% state of charge) without Na plating can be achieved, with a great capacity retention of 91.5% over 200 cycles. Further, the assembled power‐type Na3V2(PO4)3||HC pouch cell displays an impressive fast‐charging capability of 50C, which surpasses that of previously reported high‐power SIBs. This work serves as an enlightenment for developing fast‐charging SIBs.