An Ultrahigh-Power Mesocarbon Microbeads|Na+-Diglyme|Na3V2(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 Na3V2(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 approximate to 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.

Automated summary

The authors demonstrated an ultrahigh power sodium-ion battery prototype utilizing high-rate NVP cathode, MCMB anode, and Na+-diglyme electrolyte, achieving remarkable rate capability. The study showed that the cathode's overpotential follows Ohmic rule, allowing for high electronic conductivity and reduced charge transfer resistances. This highly efficient full-cell SIB achieved an energy density of 88 Wh kg(-1) at a power density of around 10 kW kg(-1), with potential for large-scale applications in the future.