Realizing a 3 C Fast‐Charging Practical Sodium Pouch Cell

Abstract Sodium‐ion batteries (SIBs), endowed with relatively small Stokes radius and low desolvation energy of 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 ≤1 C, 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 3 C charging is successfully developed via phosphorus (P)‐sulfur (S) interphase chemistry. By rational electrolyte regulation, desired P−S constituents, namely, Na 3 PO 4 and Na 2 SO 4 , 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 Na 3 PO 4 interphase, while Na 2 SO 4 expedites charge carrier mobility due to its intrinsically high ionic conductivity. Consequently, an energy‐dense (126 Wh kg −1 ) O3‐Na(Ni 1/3 Fe 1/3 Mn 1/3 )O 2 ||HC pouch cell capable of 3 C 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 Na 3 V 2 (PO 4 ) 3 ||HC pouch cell displays an impressive fast‐charging capability of 50 C, which surpasses that of previously reported high‐power SIBs. This work serves as an enlightenment for developing fast‐charging SIBs.