Enhancing Hydrogen Storage Kinetics and Cycling Properties of NaMgH3 by 2D Transition Metal Carbide MXene Ti3C2

Zhouming Hang,Zhencan Hu,Meng Zhang,Xuezhang Xiao,Ruicheng Jiang

doi:10.3390/pr9101690

Zhouming Hang, Zhencan Hu + Show 3 more

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https://doi.org/10.3390/pr9101690

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Abstract

Metal hydrides have recently been proposed for not only hydrogen storage materials but also high-efficiency thermal storage materials. NaMgH3 contains a considerable theoretical thermal storage density of 2881 kJ/kg. However, its sluggish de/re-hydrogenation reaction kinetics and poor cycling stability exhibit unavailable energy efficiency. Doping with active catalyst into NaMgH3 is deemed to be a potential strategy to mitigate these disadvantages. In this work, the enhancement of de/re-hydrogenation kinetics and cycling properties of NaMgH3 is investigated by doping with lamellar-structure 2D carbon-based MXene, Ti3C2. Results shows that introducing 7 wt.% Ti3C2 is proved to perform excellent catalytic efficiency for NaMgH3, dramatically reducing the two-step hydrogen desorption peak temperatures (324.8 and 345.3 °C) and enhancing the de/re-hydrogenation kinetic properties with the hydrogen desorption capacity of 4.8 wt.% H2 within 15 min at 365 °C and absorption capacity of 3.5 wt.% H2 within 6 s. Further microstructure analyses reveal that the unique lamellar-structure of Ti3C2 can separate the agglomerated NaMgH3 particles homogeneously and decrease the energy barriers of two-step reaction of NaMgH3 (114.08 and 139.40 kJ/mol). Especially, lamellar-structure Ti3C2 can improve the reversibility of hydrogen storage of NaMgH3, rendering 4.6 wt.% H2 capacity remained after five cycles. The thermal storage density of the composite is determined to be 2562 kJ/kg through DSC profiles, which is suitable for thermal energy storage application.

Highlights

Sodium-based hydrides such as NaH, MgH2, NaBH4, NaAlH4, and NaMgH3 have been researched as promising candidates for hydrogen storage or thermal energy storage during the past decades [1,2,3,4,5,6,7,8]
It has been proved that adding Li or K into NaMgH3 would make Li or K partially take the place of the Na position and the formation of distorted perovskite structure would enhance the dehydrogenation kinetics performance [17,18]
The successful synthesis of lamellar-structure MXene Ti3 C2 was confirmed through XRD and SEM analyses (Figure 1)

Summary

Introduction

Sodium-based hydrides such as NaH, MgH2 (simple binary hydrides), NaBH4 (borohydride), NaAlH4 (alanates hydride), and NaMgH3 (perovskite hydride) have been researched as promising candidates for hydrogen storage or thermal energy storage during the past decades [1,2,3,4,5,6,7,8]. The further applications to thermal energy storage are limited by sluggish de/re-hydrogenation kinetic performance and pronounced degradation of cycling properties of NaMgH3. Much attention has been focused on improving de/re-hydrogenation kinetics performance and cycling properties of NaMgH3 during the last few decades [17,18,19,20,21]. It was confirmed that TiF3 can significantly reduce the activation energy of NaMgH3 to

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Results

Conclusion