A first-principles investigation of α, β, and γ-MnO₂ as potential cathode materials in Al-ion batteries

Abstract

An inexpensive and eco-friendly alternative energy storage solution is becoming more in demand as the world moves towards greener technology.

Engineering Aqueous Zn-MnO2 Microbatteries Using a Synergistic Reaction Mechanism

“…43 Different crystal structures have different ion diffusion paths and thus exhibit different storage capacities and storage mechanisms. 44 Compared with MnO 2 of other crystal structures, α-MnO 2 has a significantly more stable and larger 2 × 2 (4.6 Å × 4.6 Å) tunneling structure, resulting in more stable capacity retention and higher capacity. 45 If the MnO 2 particles are excessively bulky, it will lead to slow and uneven penetration of the electrolyte into the electrode.…”

“…Due to the different connection methods, MnO 2 has various crystal structures, such as α-MnO 2 , β-MnO 2 , γ-MnO 2 , and δ-MnO 2 . Different crystal structures have different ion diffusion paths and thus exhibit different storage capacities and storage mechanisms . Compared with MnO 2 of other crystal structures, α-MnO 2 has a significantly more stable and larger 2 × 2 (4.6 Å × 4.6 Å) tunneling structure, resulting in more stable capacity retention and higher capacity .…”

Recent Achievements in Experimental and Computational Studies of Positive Electrode Materials for Nonaqueous Ca- and Al-Ion Batteries

“…142−145 Upon Al-ion insertion, the evolution of the unit cell volume, electronic structure, diffusion barrier, and binding energy parameters were studied for different MnO 2 polymorphs. 142 Of these, γ-MnO 2 was found to exhibit the lowest binding energy and diffusion barrier, thus setting a standard reference for selecting MnO 2 -based cathode materials for AIBs (Figure 8a−c). MoO 3 , as reported by Das et al, was predicted to offer a theoretical Al-insertion voltage of 1.6 V. 144 On the basis of DFT calculations of the MXene-based M 2 CT 2 (M = Ti, V, Cr, Mn, Fe, Co, and Ni; T = O and S) series, Lee et al proposed the potential use of Fe 2 CS 2 MXene as an AIB cathode.…”

“…Hydrogen-substituted graphdiyne materials could reach a storage capacity of 456 mAh g –1 . In addition, several cathodes, including MnO 2 and V 2 O 5 polymorphs, MoO 3 , and Fe 2 CS 2 MXenes have been subjected to DFT-based computational studies using Al ion as a charge carrier. − Upon Al-ion insertion, the evolution of the unit cell volume, electronic structure, diffusion barrier, and binding energy parameters were studied for different MnO 2 polymorphs . Of these, γ-MnO 2 was found to exhibit the lowest binding energy and diffusion barrier, thus setting a standard reference for selecting MnO 2 -based cathode materials for AIBs (Figure a–c).…”

“…Al ions diffusion paths in MnO 2 structures and their corresponding energy barrier profiles: (a) α-, (b) β-, and (c) γ-MnO 2 , respectively. Reprinted with permission from ref , copyright 2020 Royal Society of Chemistry. (d) Intercalation energy diagram of Al-intercalated M 2 CT 2 .…”