Controllable synthesis of crystalline germanium nanorods as anode for lithium-ion batteries with high cycling stability.

Germanium (Ge) nanomaterials have emerged as promising anode materials for lithium-ion batteries (LIBs) due to their higher capacity compared to commercial graphite. However, their practical application has been limited by the high cost associated with harsh preparation conditions and the poor electrode cycling stability in charging and diacharging. In this study, we successfully synthesized crystalline Ge nanorods through the reaction of intermetallic compound CaGe and ZnCl2. Ge nanorods with different morphologies and crystallinity can be obtained through precisely controlling the reaction temperature. When employed as electrodes for LIBs, the Ge nanorods demonstrate exceptional long-term cyclic stability. Even after 1000 cycles at a high rate of 2C (1C = 1600 mA g-1), it exhibits a remarkable reversible capacity of around 1000 mAh/g. Furthermore, such Ge electrode displays excellent cycling performance across a wide temperature range. And it could achieve reversible capacities of 1267, 832, and 690 mAh/g, with the rate of 1C, at temperatures of 20, 0, and -20 °C, respectively. Above all, our study offers a cost-effective approach for the synthesis of crystalline Ge nanorods, addressing the concerns associated with high production costs. And the application of Ge nanorods as anode materials in LIBs over a wide temperature range opens up new possibilities for the development of advanced energy storage systems.

Achieving a Record Scintillation Performance by Micro-Doping a Heterovalent Magnetic Ion in Cs3 Cu2 I5 Single-Crystal.

An ultrabright, ultrafast, and low-cost ideal scintillator has been critically absent and is sorely desired in scintillation detection, but has hitherto not been found. Here, a high-quality bulk Cs3 Cu2 I5 :Mn single-crystal scintillator with ultrahigh light yield (≈95 772 photons per MeV, 137 Cs γ-rays), excellent energy resolution (3.79%, 662 keV), and ultrafast scintillation decay time (3 ns, 81.5%) is reported. In mechanism, it is found that micro-doping of a heterovalent magnetic ion (at the ppm level) can effectively modulate the luminescence kinetics of self-trapped excitons in the scintillator. Compared with previous reports, the introduction of trace amounts of magnetic Mn2+ (≈18.6 ppm) in Cs3 Cu2 I5 single-crystal shortens the scintillation decay time by several hundred times, transforming the slow decay into an ultrafast decay. Simultaneously, the light yield is also increased about three times to the highest value so far. From the comprehensive performance of the micro-doped Cs3 Cu2 I5 :Mn single-crystal, these excellent scintillation properties, physical characteristics suitable for practical applications, and low-cost advantages render this single-crystal an ideal scintillator with great potential for commercialization.