Effective 3D open-channel nanostructures of a MgMn₂O₄ positive electrode for rechargeable Mg batteries operated at room temperature

Abstract

Room-temperature operations of rechargeable Mg coin-cell batteries have been achieved using a spinel MgMn2O4 powder having a large specific surface area > 200 m2 g–1 and more than 90% porosity with a triple-tiered 3D open-channel network.

Phenylphosphonate surface functionalisation of MgMn2O4 with 3D open-channel nanostructures for composite slurry-coated cathodes of rechargeable magnesium batteries operated at room temperature

“…The initial discharge capacity agreed well with the value ($100 mA h g À1 ) expected for the pristine structured MgMn 2 O 4 with the BET surface area of $100 m 2 g À1 , when evaluated at 25 C using coin-type full cells with dry composite cathodes at the active material : AB : PTFE weight ratio of 60 : 30 : 10. 23 These results demonstrate that the phenylphosphate functionalisation of the structured MgMn 2 O 4 surface signicantly improves the current collection efficiency in slurry-coated cathodes with high active material fractions. The improvement in the electrical contact between the surfacefunctionalised MgMn 2 O 4 and CNTs is attributed to p interactions between phenyl groups and carbon surfaces, increasing their affinity.…”

“…The observed patterns were essentially identical to the patterns for pristine samples reported previously. 20,23 The broadening of diffraction peaks indicate nanocrystalline nature of the samples. The surface functionalisation did not change the diffraction pattern.…”

“…Rechargeable magnesium batteries (RMBs) have attracted attention because Mg has high natural abundance and is safer to handle than Li in metal anodes, and the divalent mobile Mg 2+ ions can increase the energy density of active materials. [1][2][3][4] Promising cathode materials for RMBs include transition metal spinel oxides, such as AB 2 O 4 (A ¼ Mg, Zn, Mn; B ¼ Mn, Fe, Co, Ni) [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] and ZnMnO 3 . 24 These compounds discharge at an operating voltage of $2-3 V vs. Mg/Mg 2+ along with Mg 2+ ion insertion and simultaneous transformation into Mg-rich rock-salt-like phases.…”

“…A general approach to enhance the insertion and extraction of Mg 2+ ions is to reduce the particle size of host lattice and minimise the diffusion length of Mg 2+ ions in it. 11,12,14,[18][19][20]23,25,26 Recently, structured MgMn 2 O 4 (theoretical discharge capacity: 270 mA h g À1 ) with continuous three-dimensional (3D) macroand mesopores has been synthesised 20,23 by a propylene-oxidedriven sol-gel method. [27][28][29] Because of the small particle size ($10 nm), high surface area ($100-300 m 2 g À1 ), and controlled bimodal pore size distribution in the micrometre (1-10 mm) and nanometre (10-100 nm) regions, cathodes of the material prepared by the sol-gel method outperform those of conventionally prepared MgMn 2 O 4 .…”

Revisiting Delithiated Li_1.2Mn_0.54Ni_0.13Co_0.13O₂: Structural Analysis and Cathode Properties in Magnesium Rechargeable Battery Applications

“…Recently, a new class of electrolyte materials those compatible with magnesium metallic anode and possessing sufficient oxidative stability has been developed. [19][20][21][22][23] Therefore, through the appropriate cell assembly, it will be possible to achieve the full cell that performance exceeding the current LIBs.…”