Morphology effects in MgH2 anode for lithium ion batteries

Abstract

In order to acquire reproducible electrodes relevant for Li ion batteries new MgH 2 electrodes are successfully obtained from homogenous slurries in N-Methyl-2-Pyrrolidone "NMP" solvent. The electrodes are aimed to elucidate the contribution of the cell components to the electrochemical cycling, in terms of morphology and composition. Various electrode preparations were tested and compared regarding their interaction with Li in a half-cell. The obtained electrochemical cycling curves are discussed according to the ball-milling-induced structural morphology changes and presence of carbon additives, along with the effect of the kinetic rate on the conversion reaction mechanism.

MgH2–CoO: a conversion-type composite electrode for LiBH4-based all-solid-state lithium ion batteries

“…TEM analysis indicates that the 24 h milled MgH 2 powders have an average particle size of about 150 nm. 8,9 The starting hand-mixed CoO powders are in the micron range. However, aer Spex-milling, Fig.…”

“…4,6 However, the reversible capacity is still limited owing to the poor conductivity of the involved entities (MgH 2 /LiH), along with transient aging issues of LiH in carbonate-based liquid electrolytes. [7][8][9] Using amorphous 80Li 2 S-20P 2 S 5 as a solid electrolyte (SE), Ikeda et al 10 reported $31% reversible capacity for MgH 2 for the 1 st cycle at room temperature, compared to $75% for liquid electrolytes. 6 Possible interaction at the electrode/SE (80Li 2 S-20P 2 S 5 ) interface is pointed out as a cause for the low reversible capacity.…”

“…The nal goal is to promote the cycling reversibility and inhibit the formation of Li-Mg alloys for low voltage operation in the presence of an oxide with large voltage window and better cycling response upon discharge/charge. Considering the effect of the cell assembly (additives, heat treatment, mechanical pressing) which may inuence the cycling performance, 5,7,8,10,32 the optimization of the design of the battery cells was performed rst with MgH 2 electrode without CoO addition. The prepared and optimized composite electrodes were characterized using powder X-ray diffraction (PXD), X-ray photoelectron spectroscopy (XPS) and scanning transmission electron microscopy (STEM) before and aer the electrochemical tests toward Li metal.…”

Exploits, advances and challenges benefiting beyond Li-ion battery technologies

“…From the early works, it was observed that the reaction is thermodynamically favorable (as G f (MgH 2 )/2 > G f (LiH)) but kinetically sluggish. This can be overcome by a cautious nanostructuring of MgH 2 [277,278] and by tuning the composition of the composite electrode (by using additives of carbon and polymer binder, like carboxymethyl cellulose) [279,280] to handle the poor electronic conductivity of the hydride and large volume changes (84%) upon lithiation. Despite these efforts, even if the lithiation is straightforward, delithiation remains very challenging at room temperature for this hydride.…”

Metal (boro-) hydrides for high energy density storage and relevant emerging technologies

“…Metal hydrides have been considered as potential anode materials for Li-ion batteries due to their large capacities and low average potential value versus Li + /Li 0 . Since the discovery of the electrochemical activity of metal hydrides towards lithium, MgH2 (theoretical capacity ~2000 mAh g -1 ) remains the most studied in this category of anodes for LIBs using a carbonate-based liquid electrolyte [17,18,[342][343][344][345][346][347][348][349].…”