Complex hydrides as thermal energy storage materials: characterisation and thermal decomposition of Na2Mg2NiH6

Humphries, Terry D.; Sheppard, Drew A.; Li, Guanqiao; Rowles, Matthew R.; Paskevicius, Mark; Matsuo, Motoaki; Aguey-Zinsou, Kondo Francois; Sofianos, M. Veronica; Orimo, Shin Ichi; Buckley, Craig E.

doi:10.1039/c8ta00822a

Cited by 26 publications

(9 citation statements)

References 53 publications

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“…Experimental results showed that the decomposition of Na 2 Mg 2 FeH 8 is a three‐stage reaction with dehydrogenation enthalpies of 93, 87, and 111 kJ mol −1 ‐H 2 , respectively . The decomposition of Na 2 Mg 2 NiH 6 , on the other hand, is a two‐step reaction with the overall dehydrogenation enthalpy of 94 kJ mol −1 ‐H 2 , and can be operated in the temperature range of 318–568 °C under H 2 pressures from 1 to 150 bar . Light metal complex hydrides such as alanates, borohydrides and amide–hydride composites can also be used as thermal energy storage materials.…”

Section: Thermal Energy Storagementioning

confidence: 99%

Complex Hydrides for Energy Storage, Conversion, and Utilization

2019

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functionalities and exhibit great potentials for the applications in the energy transfer chain (Figure 1).In chemistry, a hydride is a compound having negatively charged hydrogen anion. [2] Nowadays, however, hydrogenous compounds having hydrogen bonded to metals or nonmetal in ionic, metallic or covalent manner are collectively referred as hydrides. [3] Complex hydride is such a class of compound having a general formula of M(XH n ) m , where M is usually a metal cation and X is a metal or nonmetal element which sets up covalent or ionocovalent bonding with H. [4] The M[XH n ] m is H-rich and can decompose selectively to H 2 allowing complex hydrides of light-weight elements potential hydrogen storage media. As a matter of fact, since the pioneering work of Ti-catalyzed NaAlH 4 in 1997, [5] extensive investigations on hydrogen storage over alanates, [6] amide-hydride composites, [7] borohydrides, [8] amidoboranes [9] as well as metallorganic hydrides [10] were carried out and tremendous progress has been made (Figure 2). [1,4a] The break and setup of XH bonding would be endergonic and exergonic, respectively. The energy input and output in hydrogen desorption and reabsorption over a complex hydride depends strongly on its thermodynamic stability, which also offers an opportunity of using complex hydrides as thermal energy storage materials to cope up with the intermittent, fluctuating and unstable supply of renewable energies. Owning to their exclusive advantages of diversity, high energy densities and tunability, complex hydrides have been actively pursued for this application since year 2000. [11] Solid electrolytes with fast conduction of Li, Na, or Mg ions are highly demanded for all-solid-state batteries with high energy density and safety. Coincidentally, complex hydrides are composed of those cations and a relatively large sized [XH n ] anion. The coordination flexibility of the large anion with alkali or alkaline earth cation would create some favorable structural features, such as defects and/or low-barrier diffusion channels, to facilitate cation migration within the lattice of complex hydrides. [12] Starting from the finding of high Li-ion conduction in the high-temperature-phase LiBH 4 , [13] a variety of complex hydrides has been developed, some of which show superior ion conductivity to their nonhydride peers. [14] Hydrogen storage over complex hydride would undergo dihydrogen dissociation into surface H atoms followed by H Functional materials are the key enabling factor in the development of clean energy technologies. Materials of particular interest, which are reviewed herein, are a class of hydrogenous compound having the general formula of M(XH n ) m , where M is usually a metal cation and X can be Al, B, C, N, O, transition metal (TM), or a mixture of them, which sets up an iono-covalent or covalent bonding with H. M(XH n ) m is generally termed as a complex hydride by the hydrogen storage community. The rich chemistry between H and B/C/N/O/Al/TM allows complex hydrides of diverse compo...

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Section: Thermal Energy Storagementioning

confidence: 99%

Complex Hydrides for Energy Storage, Conversion, and Utilization

2019

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“…Also the interest towards metal hydrides is not recent, these thermochemical storage systems were explored since the mid-1970s [264]. Several applications and different metal hydrides systems were explored for thermochemical heat storage [265][266][267][268][269].…”

Section: Thermochemical Processes and Materialsmentioning

confidence: 99%

A Review of Thermochemical Energy Storage Systems for Power Grid Support

et al. 2020

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Power systems in the future are expected to be characterized by an increasing penetration of renewable energy sources systems. To achieve the ambitious goals of the “clean energy transition”, energy storage is a key factor, needed in power system design and operation as well as power-to-heat, allowing more flexibility linking the power networks and the heating/cooling demands. Thermochemical systems coupled to power-to-heat are receiving an increasing attention due to their better performance in comparison with sensible and latent heat storage technologies, in particular, in terms of storage time dynamics and energy density. In this work, a comprehensive review of the state of art of theoretical, experimental and numerical studies available in literature on thermochemical thermal energy storage systems and their use in power-to-heat applications is presented with a focus on applications with renewable energy sources. The paper shows that a series of advantages such as additional flexibility, load management, power quality, continuous power supply and a better use of variable renewable energy sources could be crucial elements to increase the commercial profitability of these storage systems. Moreover, specific challenges, i.e., life span and stability of storage material and high cost of power-to-heat/thermochemical systems must be taken in consideration to increase the technology readiness level of this emerging concept of energy systems integration.

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“…In addition, a splitting of the NaH Bragg peaks is observed to occur above 100 °C which is associated with the dissolution of NaOH impurities into the NaH lattice. 11 From TGA, the mass loss in the first decomposition step was measured as 16.8 %, while quantitative Rietveld refinement determined that 85 wt% of NH4Cl has been consumed along with 100 % NaH, giving a weight loss of 16% consisting of 0.85NH3 and 0.925H2. The remaining NH4Cl decomposes in an endothermic process, with a maximum rate of H2 and NH3 release at ~215 °C, leaving NaCl as the only crystalline product.…”

Section: Thermal Decomposition Of Pure Nh4clmentioning

confidence: 99%

“…They have the capacity to be developed from inexpensive or abundant materials such as sodium, magnesium, calcium and titanium and form a variety of hydrogen containing species including ionic hydrides, complex hydrides and interstitial hydrides. [7][8][9][10][11] The thermal energy density of metal hydrides is up to thirty times more than molten salts, currently used to store solar energy. 3,12,13 They also have the potential to reversibly absorb large amounts of hydrogen which makes them ideal for fuel cell applications.…”

Section: Introductionmentioning

confidence: 99%