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The rapid development of flexible and wearable electronics calls for advanced batteries with high safety, long cycling stability, and low cost. Aqueous Zn metal batteries (ZMBs) are some of the most promising candidates. The main challenges are the water-induced parasitic reactions (corrosion and passivation) and dendrite-driven battery failure in traditional liquid electrolytes. Developing new electrolyte systems is critical to overcoming these issues. Herein, an ultrastrong self-standing gelatin-based solid-state electrolyte (GSE) formed by strong hydrophobic interaction between gelatin molecule chains is first introduced for stable solid-state ZMBs. The GSEs prepared by a facile soaking strategy contain much less free water compared to conventional electrolyte systems and exhibit the highest fracture tensile strength of 2.78 MPa among the reported self-standing single-component solid-state electrolytes for ZMBs, which effectively inhibit the corrosion/passivation reaction and enable the Zn/Zn symmetric cells to stably cycle at hitherto the highest current density of 5 mA cm−2 with record high cumulative plating/stripping capacity. Meanwhile, the solid-state Zn/MnO2 full cell can deliver a high reversible specific capacity of 285 mA h g−1, superior cycling stability (90% capacity retention/500 cycles), and excellent safety under extreme working circumstances. The impressive performance sheds light on the design and applications of robust solid-state electrolytes for ZMBs. [ABSTRACT FROM AUTHOR]

The Na-O2 battery system is attracting increasing attention due to its superiority in specific capacity and cost. However, its practical implementation is hindered by many issues, such as high charge-discharge overpotential, limited cycling life, and poor reversibility, all of which result from the mediocre O2 electrode. Herein, to surmount these critical challenges, hierarchical Co3O4@MnCo2O4.5 nanocubes (h-Co3O4@MnCo2O4.5 Ns) with a yolk-shell structure are designed for the first time as the novel O2 electrode. h-Co3O4@MnCo2O4.5 Ns are synthesized from a metal-organic framework via a template-assisted method, which is demonstrated to be helpful in creating a high specific surface area of 130.4 m2 g-1, a hierarchical macro- and mesoporous structure, and synergistic yolk-shelled Co3O4@MnCo2O4.5 active sites. These unique structural properties endow h-Co3O4@MnCo2O4.5 Ns with remarkably enhanced electrocatalytic activity towards both the ORR and OER. The Na-O2 battery based on h-Co3O4@MnCo2O4.5 Ns displays an ultrahigh initial discharge capacity of 8400 mA h g-1, ultralow charge-discharge overpotential of 0.45 V, long cycling life of 135 cycles, and excellent rate capability.

In this study Er³⁺ doped CaMoO₄ (CaMoO₄:Er³⁺), and Er³⁺/Yb³⁺-co-doped CaMoO₄ (CaMoO₄:Er³⁺Yb³⁺) nanoparticles have been synthesized by the microwave-assisted metathetic method. Er³⁺/Yb³⁺ co-doped CaMoO₄ nanoparticles sintered at 600 °C showed the strongest photoluminescence intensity, and crystallized well. At the excitation of 980 nm, the CaMoO₄ nanoparticles show the strongest green emission at the 520 nm and 550 nm emission bands. Moreover, the green light produced has a better color purity.