Heterogeneous structured-metal sulfides are widely used in various applications due to their excellent electrochemical activity. We report a facile synthesis of Cu_1.75S/Cu_1.8S microspheres assembled with mesoporous nanosheets and their application in sodium-ion batteries. This unique structure is obtained by a simple reaction of Cu₂O octahedra and Na₂S in an optimized molar ratio of 1–2.5 in an aqueous solution at room temperature without any other capping agents and chemicals. It is revealed that roxbyite Cu_1.75S has preferential growth along the c direction leading to nanosheets with highly exposed (008) facets. The Cu_1.75S is transformed into a digenite Cu_1.8S phase without a significant morphological change by a thermal treatment. The Cu_1.75S and Cu_1.8S microspheres with thin sheets have particle sizes of ∼2 μm, surface areas of 5.9 and 3.3 m² g^–1, and mesopores mainly in a range of 2–50 nm. Remarkable sodium storage properties were achieved, including charge capacities of 324 and 327 mAh g^–1 at 0.1 C, stable cyclabilities of 93% and 96% over 500 cycles at 3 C, and high-rate capabilities of 285 (88%) and 290 mAh g^–1 (90%) at 3 C in a voltage range of 0.3–2.1 V versus Na/Na⁺.

中文翻译：

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介孔纳米片组装的富金属Cu _1.75 S和Cu _1.8 S微球的快速生长及其在钠离子电池中的应用

异质结构化金属硫化物由于其优异的电化学活性而广泛用于各种应用中。我们报道了介孔纳米片组装的Cu _1.75 S / Cu _1.8 S微球的简便合成及其在钠离子电池中的应用。这种独特的结构是通过在室温下，水溶液中Cu ₂ O八面体和Na ₂ S的最优化摩尔比为1-2.5的简单反应而获得的，无需任何其他封端剂和化学物质。揭示了方铁铜_1.75 S在c方向上具有优先生长，从而导致纳米片具有高度暴露的（008）面。铜_1.75通过热处理，S被转化为地绿石Cu _1.8 S相，而没有明显的形态变化。薄的Cu _1.75 S和Cu _1.8 S微球的粒径约为2μm，表面积分别为5.9和3.3 m ² g ^–1，中孔主要在2–50 nm范围内。钠的存储性能显着，包括在0.1 C下的充电容量为324和327 mAh g ^–1，在3 C下500个循环下的稳定循环能力分别为93％和96％，以及高倍率能力为285（88％）和290相对于Na / Na ^+，在0.3–2.1 V的电压范围内，于3 C时mAh g ^–1（90％）。