Realizing a 3 C Fast‐Charging Practical Sodium Pouch Cell

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, 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(Ni_1/3Fe_1/3Mn_1/3)O₂||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 Na₃V₂(PO₄)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.