Lithium metal storage in zeolitic imidazolate framework derived nanoarchitectures

© 2020 Elsevier B.V. Due to the increasing demands for energy storage devices with higher energy density, lithium (Li) metal is considered to be the ultimate choice as an anode material because it has a high theoretical capacity (3860 mAh g−1) and the lowest reduction potential (−3.04 V versus standard hydrogen electrode) among all the alkali metals. Despite these advantages, repeated Li plating/stripping during cell operation leads to dendritic Li and the formation of irreversible Li (dead Li), leading to internal short-circuits and capacity fading. These fundamental problems cause safety issues and cell failure, so they must be resolved to commercialize Li-metal anode. Many in-depth studies are ongoing to solve these drawbacks through a variety of approaches, such as the formation of artificial solid-electrolyte interphase (SEI), inserting an interfacial layer between the electrolyte and electrode, demonstrating three-dimensional structured electrodes, and using stable host structures to store Li-metal. In this Review, we focus on using host materials to store Li-metal among various strategies, which may be regarded as an alternative method but is very feasible. Also, we propose porous carbon materials derived from zeolitic imidazolate frameworks (ZIFs) as the host materials due to their suitable properties for Li-metal storage. To advance progress towards practical application, the Li-metal storage capacity of porous materials is mathematically inferred, and further strategies are discussed for improving the storage capacity in this regard. Finally, we presented a perspective that paves the way for applying host materials to anodes of practical Li-metal battery

Design of cobalt catalysed carbon nanotubes in bimetallic zeolitic imidazolate frameworks

Carbon nanotubes are the most effective way to enhance electrical conductivity between particles, although the growth mechanism in zeolitic imidazolate frameworks still remains elusive. According to our density functional theory calculations and experimental studies, the role of cobalt nanoparticles as catalysts was proved to induce graphitization during pyrolysis. In particular, the sizes and exposed facets of the Co particles play an important role in triggering a hierarchical carbon nanotubes. This work paves the way to control the growth of carbon nanotubes toward various applications

Structurally stabilized lithium-metal anode via surface chemistry engineering

Dendrite-free lithium (Li) has been the primary issue for the practical application of metallic Li anode. Repeated Li plating/stripping is known to inevitably lead to severe volume changes and gradual Li dendrite growth, eventually resulting in irreversible Li (called dead-Li) as an unexpected feature. In order to avoid the dead-Li, a lithiophilic surface is highly desirable and a nanoarchitectured host for metallic Li is also required. Herein, cobalt-embedded, mesoporous, nitrogen-doped graphite (N-doped graphite) is strategically proposed as a new innovative Li-metal storage host. After tuning the surface chemistry, the material shows high Li ion affinity as well as a highly lithiophilic surface, which is attributed to the low formation energy of N-doped graphite, strongly supported by density functional theory calculations. As a result, the desirable anode shows excellent electrochemical performance with high Li-metal reversible capacity and even stable long-term cyclability with no dead-Li formation. Our findings pave the way to optimize the Li-metal host up to the limit of the theoretical capacity.11Nsciescopu