An Ultrahigh-Power Mesocarbon Microbeads|Na⁺ -Diglyme|Na₃ V₂ (PO₄ )₃ Sodium-Ion Battery

Sodium-ion batteries (SIBs) show practical applications in large-scale energy storage systems. But, their power density is limited by the sluggish Na⁺ diffusion into the cathode and anode materials. Herein, the authors demonstrate a prototype of ultrahigh power SIB, consisting of the high-rate Na₃ V₂ (PO₄ )₃ (NVP) cathode, graphite-type mesocarbon microbeads (MCMB) anode, and Na⁺ -diglyme electrolyte. It is found that the overpotential of the NVP cathode obeys the Ohmic rule. Thus, the as-synthesized NVP@C@carbon nanotubes (CNTs) cathode with the high conductive CNTs networks displays high electronic conductivity, reducing the overpotential and charge transfer resistances and leading to the remarkable rate capability over 1000C. For the MCMB anode, the initial [Na-diglyme]⁺ co-intercalation step is pseudocapacitive dominated, and then the expanded graphite's layers ensure the subsequent fast ions diffusion. The rapid (de)intercalation kinetics in between the cathode and anode are well-matched. Thus, the assembled MCMB|1 m NaPF₆ in diglyme|NVP@C@CNTs full-cell SIB delivers the energy density of 88 Wh kg^-1 at the high power density of ≈10 kW kg^-1 . Even at the ultrahigh power density of 23 kW kg^-1 , an energy density of 58 Wh kg^-1 is obtained. The encouraging results of the full cell will promote the development of high-power SIB for large-scale applications in the future.