Metallic and complex hydride-based electrochemical storage of energy

Abstract

The development of efficient storage systems is one of the keys to the success of the energy transition. There are many ways to store energy, but among them, electrochemical storage is particularly valuable because it can store electrons produced by renewable energies with a very good efficiency. However, the solutions currently available on the market remain unsuitable in terms of storage capacity, recharging kinetics, durability, and cost. Technological breakthroughs are therefore expected to meet the growing need for energy storage. Within the framework of the Hydrogen Technology Collaboration Program – H2TCP Task-40, IEA's expert researchers have developed innovative materials based on hydrides (metallic or complex) offering new solutions in the field of solid electrolytes and anodes for alkaline and ionic batteries. This review presents the state of the art of research in this field, from the most fundamental aspects to the applications in battery prototypes.

Methylamine Lithium Borohydride as Electrolyte for All‐Solid‐State Batteries

“…[14] Despite significant efforts to increase the Li + conductivity of LiBH 4 -based materials at lower temperatures, e.g. using a variety of additives, nano-confinement, anion substitution or by partial dehydrogenation, [15][16][17][18][19][20][21][22][23][24] there are only few reports of sufficiently high Li + conductivity at ambient conditions, i.e. σ(Li + ) > 10 À 3 S cm À 1 .…”

Ion Conductivity in a Magnesium Borohydride Ammonia Borane Solid-State Electrolyte

“…3−9 The substitution of Li with Mg is both safer and cheaper, as they are not flammable or subject to exploding and have a larger theoretical capacity, thanks to the double charge per ion. 10,11 Despite the higher molecular mass, the use of Mg electrodes is also advantageous compared to Li ones, as these anodes have high volumetric capacity and good redox potential and magnesium is more abundant than lithium. 12 However, significant challenges have been faced in finding a suitable solid-state electrolyte exhibiting both high ionic conductivity and good oxidative/reductive stability.…”

“…The increasing global demand for renewable energy and energy storage devices is driving the ongoing research for better materials for batteries. , Li-ion-based devices are already widely used, but alternative materials based on Mg ions have been proposed for the new generation of all-solid-state batteries. − The substitution of Li with Mg is both safer and cheaper, as they are not flammable or subject to exploding and have a larger theoretical capacity, thanks to the double charge per ion. , Despite the higher molecular mass, the use of Mg electrodes is also advantageous compared to Li ones, as these anodes have high volumetric capacity and good redox potential and magnesium is more abundant than lithium . However, significant challenges have been faced in finding a suitable solid-state electrolyte exhibiting both high ionic conductivity and good oxidative/reductive stability. , New ad-hoc electrolytes need, therefore, to be developed, and inorganic solid-state ionic conductors could be viable candidates because they are intrinsically safer than liquids. , The bivalent nature of Mg ions however represents a significant obstacle to their mobility, and high values of ionic conductivity have been proved elusive for these materials .…”

Polymorphism and solid solutions of trimethylammonium monocarboranes

“…The past decade has witnessed a new focus for the utilisation of boron-hydrogen based materials as electrolytes for all-solid-state batteries. 12,25–28 Lithium borohydride and derivatives were the initial focus, while recently metal borohydrides with neutral ligands have received significant attention, and also shown applicability as divalent solid-state ionic conductors. 29–35 A highly dynamical structure is often correlated to a high cationic mobility.…”