10:45 〜 11:00
▲ [6a-A401-7] A First-Principles Study of the Potassium Insertion in Crystalline Vanadium Oxide Phases as Possible Potassium-Ion Battery Cathode Materials
キーワード：potassium ion batteries, vanadium oxide, intercalation
Potassium (K) is an element almost as abundant as sodium and with a low standard redox potential comparable to that of Li/Li+, which makes potassium ion batteries attractive and attracting increasing research interest. Especially in the investigation of suitable cathode materials some progress was made. A group of possible cathode materials which has not yet been studied in detail are crystalline vanadium oxides, although their excellent intercalation properties are known for a variety of other alkali and alkaline earth elements, including Li, Na, Mg, and Al. Since numerous vanadium oxides with different stoichiometries and with distinct phases exist in close proximity in phase space, a systematic experimental study of all possible intercalation compounds and a rationalization of the performance (insertion potentials, capacities) of different phases and of the mechanism of insertion is difficult. That is why it is important to use ab initio methods to investigate and pre-screen suitable electrode materials and make accurate predictions with regard to the above properties in a systematic way. In this study, four promising vanadium oxide phases (α-V2O5, β-V2O5, bronze- and rutile-type VO2) are investigated from first principles as potential electrode materials for K ion batteries. Insertion energetics and diffusion barriers are computed. Our results show that the monoclinic β-V2O5 provides the lowest (strongest) insertion energies for K and the lowest diffusion barriers compared to orthorhombic α-V2O5, bronze and rutile VO2. While three of these phases show an energetically favorable potassiation and relatively small diffusion barriers, VO2(R) is predicted to be incapable of electrochemical K incorporation.