Efficient potential-tuning strategy through p-type doping for designing cathodes with ultrahigh energy density.

Designing new cathodes with high capacity and moderate potential is the key to breaking the energy density ceiling imposed by current intercalation chemistry on rechargeable batteries. The carbonaceous materials provide high capacities but their low potentials limit their application to anodes. Here, we show that Fermi level tuning by p-type doping can be an effective way of dramatically raising electrode potential. We demonstrate that Li(Na)BCF2/Li(Na)B2C2F2 exhibit such change in Fermi level, enabling them to accommodate Li+(Na+) with capacities of 290-400 (250-320) mAh g-1 at potentials of 3.4-3.7 (2.7-2.9) V, delivering ultrahigh energy densities of 1000-1500 Wh kg-1. This work presents a new strategy in tuning electrode potential through electronic band structure engineering.