NatriumVolt™: Sodium-Ion Cells with Ultra-Low-Defect Prussian White Cathode and Lignin-Derived Hard-Carbon Anode Completely Replacing Lithium and Cobalt

Preprint presenting NatriumVolt™, a 100% lithium-, nickel- and cobalt-free sodium-ion battery chemistry combining a vacancy-free Prussian White cathode (Na1.92Fe[Fe(CN)6]0.98□0.02) with a lignin-Kraft-derived hard-carbon anode (d002 = 0.378 nm) and aluminium current collectors on both electrodes. In a 200 Ah prismatic format it delivers 168 Wh/kg, 310 Wh/L, 92.5% capacity retention after 4,500 cycles at 1C/1C and 84% capacity at -30 °C, at a cell cost of US$38.50/kWh (51.9% below LFP), saving US$44 million in pack CAPEX per 1 GWh BESS while cutting cradle-to-gate CO2 by 68.3%. Includes a full laboratory protocol for Prussian White synthesis, lignin carbonization, CR2032 coin-cell assembly and chemical pre-sodiation with sodium naphthalenide.