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Owing to the low‐cost, safety, and three‐electron redox properties of aluminum, rechargeable aluminum‐ion batteries (AIBs) are emerging as a promising energy storage technology. However, exploring suitable cathode material with both elevated working voltage and high reversible capacity remains a daunting challenge. Herein, under the guidance of density functional theory calculations, V6O13 is proposed as a promising cathode candidate in AIBs for the first time. It is demonstrated that aluminum ions are reversibly stored in V6O13 by intercalation reactions, with a high discharge voltage plateau of ≈1.1 V. Of particular note a pre‐lithiation strategy is employed to further promote the redox kinetics, which endows the pre‐lithiated V6O13 nanobelt (Li–VONB) with improved capacity of 161.6 mAh g−1 and impressive energy density of 177.7 Wh kg−1 after 300 cycles, far higher than other reported oxide cathodes in AIBs. Moreover, the shielding effect of pre‐inserted Li and accelerated diffusion rate are uncovered at the atomic scale. This work develops a novel Li–VONB cathode for high‐energy AIBs, and shows the great potential of pre‐intercalation strategies in the application of AIBs. [ABSTRACT FROM AUTHOR]

Sodium borohydride (NaBH4) has been widely regarded as a potential hydrogen storage material due to its high gravimetric and volumetric capacity. Its practical application, however, is hindered by the high operating temperature of over 500 °C and extremely poor reversibility. Herein, thermodynamically favored reversible hydrogen storage performance of NaBH4 is developed inside of bimetallic (NiCo) nanoporous carbon nanosheets. Benefiting from the synergetic effect of nanoconfinement and the catalytic role of NiCo alloys, the apparent activation energy for H2 desorption from NaBH4@NiCo-NC is reduced to 36.8 kJ mol−1 with the complete H2 desorption at only 400 °C, resulting in the simultaneous formation of NiB and CoB as the dehydrogenation products. More interestingly, the reversible transformation between NiB/CoB and Ni2B/Co2B that are in situ formed during the subsequent re-/dehydrogenation process acts as a B reservoir, leading to a significant decrease of Gibbs free energy change for the reversibility of NaBH4 to 1.41 eV, 0.62 eV lower than that of pure NaBH4. As a result, coupled with the catalytic role of in situ formed Co2B/Ni2B in promoting the H2 desorption performance of NaBH4, a stable reversible capacity of 9.0 wt% is realized for NaBH4 at a temperature as low as 400 °C for 5 cycles. [ABSTRACT FROM AUTHOR]

Transition-metals have emerged as promising catalyst candidates for improving the hydrogen storage properties of MgH2. However, the preparation of uniformly dispersed and extra-fine transition-metals catalysts with high catalytic activity still remains a challenge. In this paper, an electrospinning-based reduction approach is presented to generate nanostructured nickel catalyst, which is protected from irreversible fusion and aggregation in subsequent high-temperature pyrolysis, in carbon nanofibers (Ni@C) in situ. The obtained Ni@C reveals remarkable catalytic effect on improving the hydrogen storage properties of MgH2. For example, the MgH2-10 wt%Ni@C composite delivers dehydrogenation capacities of 5.79 wt% and 6.12 wt% at 280 °C and 300 °C, respectively, whereas the as-milled MgH2 hardly decomposes at the same temperature. By Arrhenius plots, the calculated Ea of the dehydrogenation of MgH2-10 wt%Ni@C is 93.08 kJ mol−1, which is 94.33 kJ mol−1 lower than that of the as-milled MgH2. Furthermore, the microstructure of Ni@C is remained during the re/dehydrogenation process and the Ni nanoparticles are still distributed homogeneously in the composite, accounting for the excellent cycling performance. This study could render combinations of ultrafine metal nanoparticles with carbon accessible, thereby, extending opportunities in catalytic applications for hydrogen storage. The homogeneously distributed Ni with refined particle size in carbon nanofibers has been synthesized successfully. A certain proportion of Ni@C and commercial MgH 2 were mechanically mixed by high-energy ball milling and the Ni@C were uniformly dispersed on the surface of MgH 2 , which enhanced the interface interaction and reduced the apparent activation energy of the dehydrogenation of MgH 2 -10 wt % Ni@C. Image 1 • Ni nanoparticles in-situ encapsulated in carbon nanofibers has been synthesized successfully by electrospinning technique. • The Ni@C catalyst was uniformly dispersed on the surface of MgH 2 by high-energy ball milling. • The MgH 2 -10 wt %Ni@C delivers a hydrogen release of 5.91 wt% in 500 s at 325 °C. • The hydrogen storage capacity of the MgH 2 -10 wt %Ni@C composite can be maintained without degradation after 20 cycles. [ABSTRACT FROM AUTHOR]