The mechanism of Mg²⁺conduction in ammine magnesium borohydride promoted by a neutral molecule

Abstract

Light weight and cheap electrolytes with fast multi-valent ion conductivity can pave the way for future high-energy density solid-state batteries, beyond the lithium-ion battery.

Beyond Hydrogen Storage—Metal Hydrides as Multifunctional Materials for Energy Storage and Conversion

“…Elaborating the influence of amorphous Mg(BH 4 ) 2 on the conduction process has recently been published [10]. In addition, Jensen et al demonstrated a conductivity of σ = 3.3 × 10 −4 S cm −1 at T = 353 K for Mg(BH 4 ) 2 •NH 3 [11]. The conclusions of this work in connection with an earlier study [12] suggest a novel ion conduction mechanism in these materials [11].…”

“…In addition, Jensen et al demonstrated a conductivity of σ = 3.3 × 10 −4 S cm −1 at T = 353 K for Mg(BH 4 ) 2 •NH 3 [11]. The conclusions of this work in connection with an earlier study [12] suggest a novel ion conduction mechanism in these materials [11]. In general, the work on Mg 2+ conductors and especially M-B-N-H systems (M = Li, Mg) has a positive impact on material properties thus increasing their potential as new battery materials [13][14][15][16].…”

Mg3(BH4)4(NH2)2 as Inorganic Solid Electrolyte with High Mg2+ Ionic Conductivity

“…15 Very recent studies have shown the possibility to reach high ionic conductivities of about 10 -5 S.cm -1 close to room temperature by adding neutral molecules to Mg(BH4)2. In this manner, Mg(en)1(BH4)2 with en being ethylene-diamine, Mg(BH4)2-NH3 and Mg(BH4)2(NH3BH3)2 reach ionic conductivities of 6x10 -5 S.cm -1 at 70°C, 16 8.5x10 -5 S.cm -1 at 70°C, 17 and 8.4x10 -5 S.cm -1 at 40°C, 18 respectively. The latter is indeed the solid compound with the highest Mg 2+ ionic conductivity reported so far.…”

A Series of Primary Alkylamine Borane Adducts CxH2x+1NH2BH3: Synthesis and Properties

“…Such a design can be done by combining NH 3 (or N 2 H 4 ) molecules with BH 4 À anions for example, [36][37] as for ammonium calcium tetra-borohydride NH 4 Ca(BH 4 ) 4 , [38] and ammine magnesium borohydride Mg(BH 4 ) 2 ⋅ NH 3 . [39] The third example is about the dihydrogen H δ + ⋅⋅⋅H δÀ bond-driven dehydrocoupling of amine boranes into polyaminoborane and borazine-linked polymeric structures. [17][18][19][20][21][22] Dihydrogen H δ + ⋅⋅⋅H δÀ bonds have not been used to their full potential.…”