Designing a High-Power Sodium-Ion Battery by in Situ Metal Plating

Sodium-ion batteries represent a drop-in technology and a more sustainable alternative to lithium-ion batteries, but higher energies and power levels are required to meet the demands for a greener electrification. Here, the design of an anode-free sodium-ion battery is presented, and the performance of the battery is discussed in terms of reduced mass and high power capabilities. The cell consists of an iron hexacyanoferrate–reduced graphene oxide composite as cathode material, the synthesis of which is tailored to achieve minimal structural defects (3%) and water content. Its high-potential redox couple FeLS(C) is stabilized at high current rates, granting the full cell high discharge voltage and power. As negative substrate, a carbon-coated aluminum foil was adopted for in situ plating/stripping of Na metal, showing very small voltage hysteresis up to an applied current of 2 mA/cm2. Overall, this simplified full-cell architecture can deliver 340 Wh/kg and 500 W/kg at nominal 1C (= 150 mA/g), retaining 80% of its capacity over 250 cycles, with the possibility of reaching 9000 W/kg at 20C. Bridging the boundaries between batteries and supercapacitors, this research aims to expand the range of possible applications for Na-ion technology.