Aqueous rechargeable zinc-ion batteries (ARZIBs) are widely considered to be potential energy storage devices because of their low toxicity, low cost and environment-friendliness. Recent studies have proved that hydrated vanadium oxides are significant cathode materials for ARZIBs. However, their low specific capacity and poor cycling stability limit their further development because of the structural instability of the resulting device. In this work, we developed a “double guarantee mechanism” composite of Ca²⁺-intercalated hydrated vanadium oxide (V₂O₅·nH₂O, abbreviated as VOH) integrated with reduced graphene oxide (rGO), denoted as CaVOH/rGO, via a facile hydrothermal process and subsequent freeze-drying method. The inserted Ca²⁺ expanded the layer spacing, greatly reduced the electrostatic interactions and increased the reversibility of the vanadium oxide, while the integrated graphene improved the conductivity and made the composite material stable during the discharge/charge process with outstanding electrochemical performances. The CaVOH/rGO//Zn battery delivered an exceptional specific capacity of 409 mA h g⁻¹ at 0.05 A g⁻¹. It also exhibited an admirable capacity retention of more than 90% (299 mA h g⁻¹) after 2000 cycles at 4.0 A g⁻¹ and an impressive energy density (381 W h kg⁻¹ at 48 W kg⁻¹). To determine the main reaction mechanisms of Zn²⁺ reversible (de)intercalation, we employed multiple ex situ analytical methods to reveal the process of Zn²⁺ storage. The results illustrated that the CaVOH/rGO three-element composite has marvelous potential as a cathode material, and this work provides a novel method to enhance the electrochemical properties of V₂O₅·nH₂O.

中文翻译：

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Ca2 +嵌入和rGO整合的“双重保证机制”确保了水性锌离子电池高性能的水合氧化钒

水性可充电锌离子电池（ARZIBs）由于其低毒性，低成本和环境友好性而被广泛认为是潜在的能量存储设备。最近的研究证明，水合氧化钒是ARZIBs的重要阴极材料。但是，由于所得装置的结构不稳定，它们的低比容量和较差的循环稳定性限制了它们的进一步发展。在这项工作中，我们开发了一种“双重保证机制”复合物，该复合物是由Ca ²⁺嵌入的水合氧化钒（V ₂ O ₅ · n H ₂ O，缩写为VOH）与还原型氧化石墨烯（rGO）集成而成，表示为CaVOH / rGO，通过简便的水热工艺和随后的冷冻干燥方法。插入的Ca ²⁺扩大了层间距，大大降低了氧化钒的静电相互作用并提高了可逆性，而集成的石墨烯则改善了电导率，并使复合材料在放电/充电过程中稳定，并具有出色的电化学性能。CaVOH / rGO // Zn电池在0.05 A g ^-1时可提供409 mA hg ^-1的出色比容量。它也显示出超过90％（299毫安汞柱的极佳容量保持^-1 4.0 A G 2000次循环后）^-1和令人印象深刻的能量密度（381 W时千克^-1在48 w ^千克^-1）。为了确定Zn ²⁺可逆（去）插层的主要反应机理，我们采用了多种非原位分析方法来揭示Zn ^2+的存储过程。结果表明，CaVOH / rGO三元复合材料作为正极材料具有极好的电势，为提高V ₂ O ₅ · n H ₂ O的电化学性能提供了一种新方法。