Because of its ultrahigh specific capacity, lithium metal holds great promise for revolutionizing current rechargeable battery technologies. Nevertheless, the unavoidable formation of dendritic Li, as well as the resulting safety hazards and poor cycling stability, have significantly hindered its practical applications. A mainstream strategy to solve this problem is introducing porous media, such as solid electrolytes, modified separators, or artificial protection layers, to block Li dendrite penetration. However, the scientific foundation of this strategy has not yet been elucidated. Herein, using experiments and simulation we analyze the role of the porous media in suppressing dendritic Li growth and probe the underlying fundamental mechanisms. It is found that the tortuous pores of the porous media, which drastically reduce the local flux of Li moving toward the anode and effectively extend the physical path of dendrite growth, are the key to achieving the nondendritic Li growth. On the basis of the theoretical exploration, we synthesize a novel porous silicon nitride submicron-wire membrane and incorporate it in both half-cell and full-cell configurations. The operation time of the battery cells is significantly extended without a short circuit. The findings lay the foundation to use a porous medium for achieving nondendritic Li growth in Li metal-based batteries.
Owing to its ultrahigh specific capacity and low electrochemical potential, lithium (Li) metal is regarded as one of the most attractive anode materials for next-generation lithium batteries. Nevertheless, the commercialization of Li-metal-based rechargeable batteries (LiMBs) has been retarded by the uncontrollable growth of Li dendrites, as well as the resulting poor cycle stability and safety hazards. In this work, a 3D graphene@Ni scaffold has been proposed to accomplish dendrite-free Li deposition via structural and interfacial synergistic effects. Due to the intrinsic high surface area used to reduce the effective electrode current density and the surface-coated graphene working as an artificial protection layer to provide high cycle stability as well as suppress the growth of Li dendrites, the Coulombic efficiencies of Li deposition on 3D graphene@Ni foam after 100 cycles can be sustained as high as 96, 98, and 92% at the current densities of 0.25, 0.5, and 1.0 mA cm, respectively, which shows more excellent cycle stability than that of its planar Cu foil and bare Ni foam counterparts. The results obtained here demonstrate that the comprehensive consideration of multiaspect factors could be more help to enhance the performance of Li metal anode so as to achieve its real application in next-generation LiMBs.
Rechargeable lithium (Li) metal batteries hold great promise for revolutionizing current energy‐storage technologies. However, the uncontrollable growth of lithium dendrites impedes the service of Li anodes in high energy and safety batteries. There are numerous studies on Li anodes, yet little attention has been paid to the intrinsic electrocrystallization characteristics of Li metal and their underlying mechanisms. Herein, a guided growth of planar Li layers, instead of random Li dendrites, is achieved on self‐assembled reduced graphene oxide (rGO). In situ optical observation is performed to monitor the morphology evolution of such a planar Li layer. Moreover, the underlying mechanism during electrodeposition/stripping is revealed using ab initio molecular dynamics simulations. The combined experiment and simulation results show that when Li atoms are deposited on rGO, each layer of Li atoms grows along (110) crystallographic plane of the Li crystals because of the fine in‐plane lattice matching between Li and the rGO substrate, resulting in planar Li deposition. With this specific topographic characteristic, a highly flexible lithium–sulfur (Li–S) full cell with rGO‐guided planar Li layers as the anode exhibits stable cycling performance and high specific energy and power densities. This work enriches the fundamental understanding of Li electrocrystallization without dendrites and provides guidance for practical applications.
A space-confined "sauna" reaction system is introduced for the simultaneous reduction and functionalization of graphene oxide to unique graphene-sulfur hybrid nanosheets, in which thin layers of amorphous sulfur are tightly anchored on the graphene sheet via strong chemical bonding. Upon being used as the cathode material in lithium-sulfur batteries, the as-synthesized composite shows an excellent electrochemical performance.
Heterostructure engineering plays a vital role in regulating the material interface, thus boosting the electron transportation pathway in advanced catalysis. Herein, a novel Bi2O3/BiO2 heterojunction catalyst was synthesized via a molten alkali-assisted dealumination strategy and exhibited rich structural dynamics for an electrocatalytic CO2 reduction reaction (ECO2RR). By coupling in situ X-ray diffraction and Raman spectroscopy measurements, we found that the as-synthesized Bi2O3/BiO2 heterostructure can be transformed into a novel Bi/BiO2 Mott–Schottky heterostructure, leading to enhanced adsorption performance for CO2 and *OCHO intermediates. Consequently, high selectivity toward formate larger than 95% was rendered in a wide potential window along with an optimum partial current density of −111.42 mA cm–2 that benchmarked with the state-of-the-art Bi-based ECO2RR catalysts. This work reports the construction and fruitful structural dynamic insights of a novel heterojunction electrocatalyst for ECO2RR, which paves the way for the rational design of efficient heterojunction electrocatalysts for ECO2RR and beyond.
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