A first-principles study of potassium insertion in crystalline vanadium oxide phases as possible potassium-ion battery c
- PDF / 641,704 Bytes
- 7 Pages / 612 x 792 pts (letter) Page_size
- 47 Downloads / 142 Views
Research Letter
A first-principles study of potassium insertion in crystalline vanadium oxide phases as possible potassium-ion battery cathode materials Daniel Koch, Vadym V. Kulish, and Sergei Manzhos, Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576, Singapore Address all correspondence to Sergei Manzhos at [email protected] (Received 11 July 2017; accepted 25 September 2017)
Abstract Four different vanadium oxide phases [α-vanadium pentoxide (V2O5), β-V2O5, bronze-type vanadium dioxide [VO2(B)], and rutile-type VO2 [VO2(R)])] are investigated from first principles as potential electrode materials for potassium (K) ion batteries. Specifically, insertion energetics and diffusion barriers are computed. These phases are known as promising cathode materials for other types of metal ion batteries. Our results show that the metastable β-V2O5 provides the lowest (strongest) insertion energies for K and the lowest diffusion barriers compared with orthorhombic α-V2O5, VO2(B), and VO2(R). While three of these phases show energetically favorable potassiation and relatively small diffusion barriers, VO2(R) is predicted to be incapable of electrochemical K incorporation.
Introduction When it comes to electrochemical energy storage, lithium (Li) ion batteries currently reach the largest market share for portable applications among all battery types. On the other hand, concerns over the longevity of existing Li resources, their distribution and the prospect of upcoming Li utilization in other kinds of technologies started to shift the focus of research toward alternative battery types. The most frequently investigated alternative to Li ions is currently sodium (Na) due to its abundance and relatively low atomic mass as well as good insertion properties for a variety of host materials. As an element almost as abundant (2.14% in the continental crust) as Na (2.36%)[1] and with an even lower standard redox potential (−2.936 V versus Na/ Na+: −2.714 V against SHE) comparable to Li/Li+ (−3.040 V[2]), the investigation of potassium (K)-based batteries has been gaining interest. Although showing advantageous behavior in terms of standard potential and a generally faster diffusion in electrolytes due to a smaller Stokes radius,[3] there are several obstacles currently preventing a more widespread application of K in batteries, like the large ionic radius of K+ (1.52 Å radius in crystal octahedral coordination versus Na+: 1.16 Å versus Al3+: 0.675 Å[4]), which limits the number of suitable host materials capable of accommodating K without significant stresses or volume expansion. Other issues are typical for the alkali metals’ safety concerns regarding the use of pure metal anodes due to their reactivity and possible dendrite formation, although the latter issue is believed to be less pronounced than for Li and Na,[5] and a generally lower specific capacity of these technologies due to K’s small valence electron number-to-atomic mass ratio compared with other elements such as
Data Loading...
