Garnet‐type solid‐state electrolytes (SSEs) have been widely studied as a promising candidate for Li metal batteries. Despite the common belief that inorganic SSEs can prevent dendrite propagation, garnet SSEs suffer from relatively low critical current density (CCD) at which the SSEs are abruptly short‐circuited by Li dendrites. In this study, the short‐circuiting mechanism of garnet Li7La2.75Ca0.25Zr1.75Nb0.25O12 (LLCZN) is investigated. It is found that instead of propagating uniaxially from one electrode to other in a dendritic form, metallic lithium is formed within the SSE. This can be attributed to the fact that electrons combine with Li ions at the grain boundary, which exhibits relatively high electronic conductivity, and then reduce Li+ to Li0 to cause short circuits. In order to reduce the electronic conductivity at the grain boundary, a thin layer of LiAlO2 is coated on the grain surface of LLCZN, which results in an improved CCD value. It is also found that under higher external voltages, the electronic conductivity of SSE becomes more significant, which is believed to be the origin of CCD. These findings not only shed light on the short‐circuiting mechanism of garnet‐type SSEs but also offer a novel perspective and useful guidance on their designs and modifications.
A flexible composite solid electrolyte membrane consisting of inorganic solid particles (Li1.3Al0.3Ti1.7(PO4)3), polyethylene oxide (PEO), and boronized polyethylene glycol (BPEG) is prepared and investigated. This membrane exhibits good stability against lithium dendrite, which can be attributed to its well‐designed combination components: the compact inorganic lithium ion conducting layer provides the membrane with good mechanical strength and physically barricades the free growth of lithium dendrite; while the addition of planar BPEG oligomers not only disorganizes the crystallinity of the PEO domain, leading to good ionic conductivity, but also facilitates a “soft contact” between interfaces, which not only chemically enables homogeneous lithium plating/stripping on the lithium metal anode, but also reduces the polarization effects. In addition, by employing this membrane to a LiFePO4/Li cell and testing its galvanostatic cycling performances at 60 °C, capacities of 158.2 and 94.2 mA h g−1 are delivered at 0.1 C and 2 C, respectively.
Aqueous Zn‐MnO2 batteries using mild electrolyte show great potential in large‐scale energy storage (LSES) application, due to high safety and low cost. However, structure collapse of manganese oxides upon cycling caused by the conversion mechanism (e.g., from tunnel to layer structures for α‐, β‐, and γ‐phases) is one of the most urgent issues plaguing its practical applications. Herein, to avoid the phase conversion issue and enhance battery performance, a structurally robust novel phase of manganese oxide MnO2H0.16(H2O)0.27 (MON) nanosheet with thickness of ≈2.5 nm is designed and synthesized as a promising cathode material, in which a nanosheet structure combined with a novel H+/Zn2+ synergistic intercalation mechanism is demonstrated and evidenced. Accordingly, a high‐performance Zn/MON cell is achieved, showing a high energy density of ≈228.5 Wh kg−1, impressive cyclability with capacity retention of 96% at 0.5 C after 300 cycles, as well as exhibiting rate performance of 115.1 mAh g−1 at current rate of 10 C. To the best current knowledge, this H+/Zn2+ synergistic intercalation mechanism is first reported in an aqueous battery system, which opens a new opportunity for development of high‐performance aqueous Zn ion batteries for LSES.
A nanoscale MOF material NMOF 1 with controllable morphologies is realized whose morphology control has been simulated based on the BFDH method. The targeted NMOF 1 exhibits highly sensitive, selective and instant "turn-on" sensing of bacterial endospores.
As
one of the promising alternatives of lithium-ion batteries,
zinc-ion batteries (ZIBs) have received growing interest from researchers
due to their good safety, eco-friendliness, and low cost. Nevertheless,
aqueous ZIBs are still a step away from practical applications due
to the nonuniform deposition of Zn and parasitic side reactions, which
cause capacity fading and even short circuit. To tackle these problems,
here we introduce a single-Zn-ion conducting hydrogel electrolyte
(SIHE), P(ICZn-AAm), synthesized with iota carrageenan (IC) and acrylamide
(AAm). The SIHE manifests single Zn2+ conductivity via
the abundant sulfates fixed on the IC polymer backbone, delivering
a high Zn2+ transference number of 0.93. It also exhibits
outstanding ionic conductivity of 2.15 × 10–3 S cm–1 at room temperature. The enhanced compatibility
at the electrode–electrolyte interface was verified by the
stable Zn striping/plating performance along with a homogenous and
smooth Zn deposition layer. It is also found that the passivation
of the Zn anode can be effectively prohibited due to the lack of free
anions in the electrolyte. The practical performance of the SIHE is
further investigated with Zn–V2O5 batteries,
which showed a stable capacity of 271.6 mA h g–1 over 150 cycles at 2 C and 127.5 mA h g–1 over
500 cycles at 5 C.
A self-healing zinc anode is achieved by introducing a liquid Ga–In–Zn alloy as a protective layer on zinc foil. The high fluidity and deformability of the liquid alloy ensure an ultralong cycling life by enabling dendrite-free Zn deposition.
A new fluorescence probe for distinguishing Zn(2+) and Cd(2+) is designed and synthesized. For the first time to our knowledge, this probe can recognize similar metal ions by coherently utilizing intramolecular charge transfer (ICT) and different electronic affinities of various metal ions, instead of by selective coordination alone, which may be interfered with and lose its selectivity easily in a complicated environment, providing a distinct recognition even by the naked eye for Zn(2+) and Cd(2+) with the sensitivity at the ppb level. This design strategy may initiate a straightforward approach for the selective detection of various metal ions with similar chemical properties in extensive applications such as environmental, industrial, and bio-science.
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