Abstract:We review the current achievements in the numerical studies of adsorption of molecular hydrogen in boron substituted nanoporous carbons. We show that the enhanced attraction of H-2 by boron-substituted all-carbon structures may allow designing new porous materials with modulated capacity for hydrogen adsorption. Such new structures are characterized by modification of energy landscape of adsorbing surfaces extending beyond the vicinity of substituted atom over several graphene carbon sites, and show strong sur… Show more
“…Notwithstanding the fact that the N‐doped carbon coated NVP materials have shown exceptional electrochemical performance, the N‐doped carbon materials are relatively sensitive to moisture and oxygen, which unfavorably affects their conductivity. Boron‐doped carbon materials prepared by using boron trichloride (BCl 3 ), borane‐tetrahydrofuran adduct (BH 3 ‐THF) or boron oxide (B 2 O 3 ) as boron agent have demonstrated high conductivity regardless of environment influence . For example, Wang et al used sodium tetraphenylborate (NaBC 24 H 20 ) as boron source to prepare the boron‐doped carbon coated NVP (NVP‐C‐B) composites via a facile sol–gel approach .…”
Section: Components Of Sodium‐ion Batteriesmentioning
Sodium-ion batteries (SIBs) have attracted increasing attention in the past decades, because of high overall abundance of precursors, their even geographical distribution, and low cost. Apart from inherent thermodynamic disadvantages, SIBs have to overcome multiple kinetic problems, such as fast capacity decay, low rate capacities and low Coulombic efficiencies. A special case is sodium super ion conductor (NASICON)-based electrode materials as they exhibit - besides pronounced structural stability - exceptionally high ion conductivity, rendering them most promising for sodium storage. Owing to the limiting, comparatively low electronic conductivity, nano-structuring is a prerequisite for achieving satisfactory rate-capability. In this review, we analyze advantages and disadvantages of NASICON-type electrode materials and highlight electrode structure design principles for obtaining the desired electrochemical performance. Moreover, we give an overview of recent approaches to enhance electrical conductivity and structural stability of cathode and anode materials based on NASICON structure. We believe that this review provides a pertinent insight into relevant design principles and inspires further research in this respect.
“…Notwithstanding the fact that the N‐doped carbon coated NVP materials have shown exceptional electrochemical performance, the N‐doped carbon materials are relatively sensitive to moisture and oxygen, which unfavorably affects their conductivity. Boron‐doped carbon materials prepared by using boron trichloride (BCl 3 ), borane‐tetrahydrofuran adduct (BH 3 ‐THF) or boron oxide (B 2 O 3 ) as boron agent have demonstrated high conductivity regardless of environment influence . For example, Wang et al used sodium tetraphenylborate (NaBC 24 H 20 ) as boron source to prepare the boron‐doped carbon coated NVP (NVP‐C‐B) composites via a facile sol–gel approach .…”
Section: Components Of Sodium‐ion Batteriesmentioning
Sodium-ion batteries (SIBs) have attracted increasing attention in the past decades, because of high overall abundance of precursors, their even geographical distribution, and low cost. Apart from inherent thermodynamic disadvantages, SIBs have to overcome multiple kinetic problems, such as fast capacity decay, low rate capacities and low Coulombic efficiencies. A special case is sodium super ion conductor (NASICON)-based electrode materials as they exhibit - besides pronounced structural stability - exceptionally high ion conductivity, rendering them most promising for sodium storage. Owing to the limiting, comparatively low electronic conductivity, nano-structuring is a prerequisite for achieving satisfactory rate-capability. In this review, we analyze advantages and disadvantages of NASICON-type electrode materials and highlight electrode structure design principles for obtaining the desired electrochemical performance. Moreover, we give an overview of recent approaches to enhance electrical conductivity and structural stability of cathode and anode materials based on NASICON structure. We believe that this review provides a pertinent insight into relevant design principles and inspires further research in this respect.
“…The optimum pore diameter/width is about 0.7 nm, as predicted by Monte-Carlo simulations. [23][24][25] Therefore, it is easy to predict that hydrogen adsorption is feasible only on the surface of graphite and not in the layers between the graphite sheets. Thus, it is necessary to expand the width between the graphite layers.…”
Section: Discussionmentioning
confidence: 99%
“…In addition, the MPV was increased by the loaded vanadium catalyst because small mesopores were changed into micropores through a special reduction process. It is well known that micropore structures are beneficial for advanced hydrogen storage 18,19,[23][24][25] ; therefore, one can expect hydrogen storage to improve with an enlarged pore structure and controlled pore size.…”
The hydrogen storage mechanism of graphite was studied by measuring the electrical resistance change. Graphite was expanded and activated to allow for an easy hydrogen molecule approach and to enlarge the adsorption sites. A vanadium catalyst was simultaneously introduced on the graphite during the activation process. The hydrogen storage increased due to the effects of expansion, activation, and the catalyst. In addition, the electrical resistance of the prepared samples was measured during hydrogen molecule adsorption to investigate the hydrogen adsorption mechanism. It was found that the electrical resistance changed as a result of the easy hydrogen molecule approach, as well as of the adsorption process and the catalyst. It was also notable that the catalyst improved not only the hydrogen storage capacity but also the speed of hydrogen storage based on the response time. The hydrogen storage mechanism is suggested based on the effects of expansion, activation, and the catalyst.
“…It aims at totally new architectures based on larger supra-molecular structures, which can be built from fragmented and chemically modified graphene structures. Typical porous activated carbon, are not able to achieve the required capacity, mainly, due to the weak energy of interaction and too low surface accessible for adsorption (below 3,500 m 2 /g, Kuchta et al 2010). Important limiting factor is the H 2 -H 2 interaction, which is not strong enough to make a multilayer hydrogen adsorption at ambient temperatures.…”
Section: Introductionmentioning
confidence: 99%
“…Many of them are not stable enough. Hydrogen can be stored in solid materials by chemisorption (atomic form) or by physisorption (molecular form) (Kuchta et al 2010;Firlej et al 2009). Metal hydrides and complex hydrides are investigated systems and well known for reversible hydrogen storage by chemisorption.…”
Hydrogen storage is a key technology for the advancement of hydrogen and fuel cell power technologies in transportation, stationary, and portable applications. The currents state of art shows that there is no existing material which could be used as efficient storage medium. In this paper we present a new concept of a non-conventional engineering storage solution. It is based on the recent theoretical and experimental discoveries which show existence of a new meta-stable phase of graphite with mixed sp 2 -sp 3 hybridization called diaphite. By means of the molecular dynamics calculations with adaptive intermolecular reactive empirical bond order potential empirical potential we show that the increase of the hydrogen-carbon binding energy on diaphite is related to the transformation of local bonds geometry from sp 2 hybridization to sp 3 . We propose and discuss a scenario of fully reversible photostimulated process of adsorption/desorption of hydrogen on/of diaphite.
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