Modulating Na plating morphology via interfacial design to achieve energy-dense and fast-charging sodium-ion batteries

Sodium (Na) plating occurring at the anode interface is considered the major hurdle for fast-charging sodium-ion batteries (SIBs), but identifying the rate-determining step remains a challenge due to the distinct cell parameters. Exploring the extended Na plating capacity, rather than its inhibition, along with compatible Na-ion intercalation chemistry on hard carbon (HC) anodes, is a practical approach to breaking through the barriers of fast-charging SIBs. Herein, we construct a NaF-rich solid electrolyte interphase (SEI) featuring high Na-ion flux and uniform species distribution to smooth Na plating morphology on HC anodes. The versatile SEI can not only facilitate reversible Na plating but also maintain its self-structural stability over repeated Na plating/stripping. When Na plating capacity contributes to 27 % of the total sodiation capacity, an average Coulombic efficiency (99.86 %) of the sodiated HC anodes can be sustained over 300 cycles. Consequently, the self-made Ah-level NaNi1/3Fe1/ 3Mn1/3O2||HC pouch cell achieves a fairly high energy density of 224 Wh (kg active)-1 at 0.2 C while delivering a remarkable state of charge of 83.2% at 3C-rate charging with a retention of 86.2% over 500 cycles. The work provides an alternative approach to address Na plating issues, advancing fast-charging and energy-dense SIBs for practices.