Can doping of transition metal oxide cathode materials increase achievable voltages with multivalent metals?

Abstract

AbstractThe use of substitutional p‐doping as a means to enhance the insertion energies of multivalent metals in transition metal oxides, and therefore the resulting voltages in an electrochemical cell, due to band structure modulation is investigated using first principles calculations. The investigations reveal the formation of n‐hole polarons (with n > 1) in the form of oxygen dimers in p‐doped charge‐transfer insulating transition metal oxides, caused by localized p holes on oxide ions in agreement with previous findings. It is found that the oxygen dimer formation has an adverse effect on adsorption energetics compared to the single‐hole case without dimerization. On the other hand, strained systems or Mott insulators with qualitatively different valence band composition do not exhibit oxygen dimerization with multihole doping. The results demonstrate the advantages and limitations of transition metal oxide electrode p‐doping and show a path to possible strategies to overcome detrimental effects.