Yajun Zhao,Pengjun Zhang,Jinrui Liang,Xiaoyu Xia,Longtao Ren,Li Song,Wen Liu,Xiaoming Sun
Advanced cathode materials play an important role in promoting aqueous battery technology for safe energy storage. Transition metal double hydroxides are usually elusive as a stable cathode for aqueous zinc-ion batteries (AZIBs) due to their unstable crystal structure, sluggish ion transportation, and insufficient active sites for zinc-ion storage. Here, a trinary layered double hydroxide (LDH) with hydrogen vacancies (Ni 3 Mn 0.7 Fe 0.3 -LDH) is reported as a new cathode material for AZIBs. A reversible high capacity up to 328 mAh g −1 can be obtained and cycle stably over 500 cycles with a capacity retention of 85%. Experimental and theoretical studies reveal that the hydrogen vacancies in LDH can expose lattice oxygen atoms as active sites for zinc-ion storage and accelerate ion diffusion by reducing the electrostatic interactions between zinc ions and the host structure. In addition, the synergy of the trinary transitional metal cations can suppress the Jahn–Teller distortion of manganese (III) oxide octahedron and enable long cycle stability. This work provides not only a series of high-performance cathode materials for AZIBs but also a novel materials design strategy that can be extended to other multi-valence metal-ion batteries.
Transition metal double hydroxides (LDHs) are among the most promising electrode materials in electrochemical energy storage. In this study, we synthesized electrodeposited nickel–cobalt layered double hydroxide (NiCo−LDH) to investigate the significant capacity gap in LDHs at different scan rates in an alkaline electrolyte. Experimental results demonstrate that the degradation of capacity at high scan rates is primarily attributed to the slow ion diffusion and the decreased reversibility of active metal ions. Furthermore, by exploiting the low reversibility of the deprotonation reaction at high scan rates, a NiCo−LDH with enriched hydrogen vacancies (H v −rich LDH) was obtained. Consequently, the H v −rich LDH, when used as the cathode in a magnesium ions hybrid supercapacitor (Mg−HSC), exhibits a high specific capacity of 94.97mAh g −1 at a current density of 1 A g −1 and maintains a significant capacity of 41.90 mAh g −1 even at 20 A g −1 . Moreover, a Mg−HSC device assembled with an H v −rich LDH cathode and a VS 2 anode delivers a high energy density of 48.44 Wh kg −1 and a power density of 937.49 W kg −1 , demonstrating its practical application value. This work not only provides a theoretical basis for the defect design of LDHs but also expands their applicability.
Lithium hydride (LiH), a saline hydride with a hydrogen density of 12.6 wt %, is highly thermostable, which hinders its extensive application in hydrogen storage. In this study, we demonstrate a distinct photodecomposition of LiH under ambient conditions. Ultraviolet–visible (UV–vis) illumination induces hydrogen release and creates surface hydrogen vacancies on LiH. The subsequent H– migration enables hydrogen desorption and the accumulation of vacancies at the subsurface, resulting in the generation of metallic Li clusters. Rehydrogenation, on the contrary, can be charged under UV–vis illumination in 1 bar H2. Such phenomena show that the thermodynamic and kinetic limits in the re/dehydrogenation of LiH can be broken under illumination, which allows hydrogen storage over the LiH surface at temperatures ∼600 K lower than those of the corresponding thermal process. This work provides new insights into the interaction of semiconducting hydrides and photons and opens an avenue for the development and optimization of materials for hydrogen storage and related photodriven reactions.
危险品化学品经营许可证（带存储）