Rechargeable magnesium-ion battery based on a TiSe2-cathode with d-p orbital hybridized electronic structure

Abstract

Rechargeable ion-batteries, in which ions such as Li+ carry charges between electrodes, have been contributing to the improvement of power-source performance in a wide variety of mobile electronic devices. Among them, Mg-ion batteries are recently attracting attention due to possible low cost and safety, which are realized by abundant natural resources and stability of Mg in the atmosphere. However, only a few materials have been known to work as rechargeable cathodes for Mg-ion batteries, owing to strong electrostatic interaction between Mg2+ and the host lattice. Here we demonstrate rechargeable performance of Mg-ion batteries at ambient temperature by selecting TiSe2 as a model cathode by focusing on electronic structure. Charge delocalization of electrons in a metal-ligand unit through d-p orbital hybridization is suggested as a possible key factor to realize reversible intercalation of Mg2+ into TiSe2. The viewpoint from the electronic structure proposed in this study might pave a new way to design electrode materials for multivalent-ion batteries.

Beyond Li-ion: electrode materials for sodium- and magnesium-ion batteries

“…Lastly, Gu et al [172] obtained similar results for VSe 2 as compared to TiSe 2 . With a major discharge plateau slightly below 1 V and a capacity of ~110 mA h g −1 , over 60 cycles were demonstrated with no apparent capacity fading.…”

“…In agreement with Liang et al [166], they point to tuning the interlayer spacing as a useful tool. However, they also note that the ease with which transition metals change valence states plays an important role in determining the diffusion barrier for Mg, which may preclude TiS 2 Gu et al [172] recently reported on TiSe 2 for the first time as an MIB cathode material. Noting the beneficial effects of electron delocalization in CP [100], the study focused on hybridization of the energetically similar Ti 3d and Se 4p atomic orbitals (Fig.…”

Readily Exfoliated TiSe2 Nanosheets for High‐Performance Sodium Storage

“…Gu et al. reported that the d‐p orbital hybridization in TiSe 2 is a possible key factor to realize reversible intercalation of Mg 2+ into TiSe 2 . As inspired by all these previous reports, TiSe 2 nanosheets are expected to be promising electrode materials for SIBs.…”

Copper Selenide as a New Cathode Material based on Displacement Reaction for Rechargeable Magnesium Batteries

“…The strong Coulomb interaction between Mg 2+ and host lattice prevents fast ion diffusion in solid-state electrodes [9], as well as the high coordinating ability of Mg 2+ ion to hard Lewis bases such as N-and O-containing functional groups. Compared to Li-ion batteries, only a few kinds of transition metal compounds, such as Chevrel phase (Mo 6 X 8 , X = S, Se) [10,11], oMo 9 Se 11 [12], MX 2 (M = Ti, Mo, W, X = S, Se) [13][14][15][16], TiS 3 [17], MgMSiO 4 (M = Fe, Mn, Co) [18][19][20], MgFePO 4 F [21], and MnO 2 [22,23], have been reported as insertion-type cathodes for Mg batteries. It is noteworthy here that these cathode materials were basically chosen from a viewpoint that Mg 2+ ions could be inserted into, and extracted from, void space of the host lattices; this type of compounds was, however, extremely limited at present.…”