Cation substitution is a promising strategy for modulating the structural properties and optimizing the electrochemical performance of spinel cobalt oxide (Co3O4); however, the underlying mechanism of this action induced by different cation substitutions has not yet been clearly addressed.

New insight into the effect of fluorine doping and oxygen vacancies on electrochemical performance of Co 2 MnO 4 for flexible quasi-solid-state asymmetric supercapacitors, Energy Storage Materials (2019),

The intrinsically poor electrical conductivity and insufficient number of electrochemically active sites of transition-metal oxides hamper their wide application in high-performance supercapacitors. Herein, we demonstrate an effective strategy of creating phosphorus-containing cobalt molybdate (CoMoO 4) with oxygen vacancies (P-CoMoO 4-x) on nickel foam for use as a supercapacitor electrode. Experimental We have demonstrated a facile strategy for creating O vacancies and incorporating P atoms in P-CoMoO 4-x nanosheets on conductive Ni foam. Experimental and theoretical studies provide insight into the effect of the introduction of P and of O vacancies on structural and electrical properties of P-CoMoO 4-x. Moreover, P incorporation into the P-CoMoO 4-x lattice induces reduction in bond energy of CoO and the formation of Mo species with a lower oxidation state, resulting in substantially enhanced redox reaction kinetics and electrochemical performance. 4 Accordingly, the optimized P-CoMoO 4-x achieves a high specific capacity of 1368 C g −1 at a current density of 2 A g −1 , and excellent electrochemical stability. The asymmetric supercapacitor P-CoMoO 4-x //AC delivers superior energy densities of 58 W h kg −1 at a power density of 850 W kg −1 .

Designing new cathodes with high capacity and moderate potential is the key to break energy density ceiling imposed by current intercalation chemistry on rechargeable battery. 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.

Via first-principles calculations, we showed that the Mg-ion diffusion energy barrier in α-V2O5 can be substantially decreased through hydrogenation.