Flexible energy storage devices show promising advantages in next-generation bendable, wearable, and implantable electronic systems, and therefore, they attract considerable interest for researchers to fulfill requirements of future energy storage devices. Here, we report a facile two-step strategy to construct flexible and binder-free NaTi₂(PO₄)₃/graphene film with a sandwich structure (GN/NaTi₂(PO₄)₃/GN). Such a design makes the resulting film with an excellent flexibility, which can be used for a binder-free anode for flexible sodium-ion batteries (SIBs). GN nanosheet supported NaTi₂(PO₄)₃ nanocrystals (NaTi₂(PO₄)₃/GN) are first prepared by a facile hydrothermal route. Then, the resultant NaTi₂(PO₄)₃/GN hybrid is embedded homogeneously in interconnected GN nanosheet framework to form three-dimensional flexible GN/NaTi₂(PO₄)₃/GN film. The flexible film exhibits excellent cycling stability (91% capacity retention over 1000 cycles at 500 mA g^–1) for sodium half cells. Furthermore, it can be assembled into flexible full SIBs (Na_0.44MnO₂ as the cathode) for practical application. The flexible full battery shows good cycling stability both under flat and bent states, maintaining 92.9% retention after the first 30 cycles under a flat state compared to the original capacity and 86% retention after another 40 cycles under a bent state. This synthesis route offers a general method for constructing other flexible films for SIBs.

中文翻译：

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通过两步石墨烯杂交策略构建具有三明治结构的柔性无粘合剂NaTi ₂（PO ₄）₃薄膜电极作为长寿命钠离子电池的超稳定阳极

柔性储能设备在下一代可弯曲，可穿戴和可植入电子系统中显示出令人鼓舞的优势，因此，它们吸引了研究人员满足未来储能设备需求的巨大兴趣。在这里，我们报告了一种简便的两步策略来构造具有三明治结构（GN / NaTi ₂（PO ₄）₃ / GN）的柔性且无粘合剂的NaTi ₂（PO ₄）₃ /石墨烯薄膜。这样的设计使所得膜具有优异的柔韧性，可用于挠性钠离子电池（SIB）的无粘合剂阳极。GN纳米片支持的NaTi ₂（PO ₄）₃纳米晶体（NaTi ₂（PO ₄）₃ / GN）首先通过简便的水热法制备。然后，将所得的NaTi ₂（PO ₄）₃ / GN杂化物均匀地嵌入互连的GN纳米片框架中，以形成三维柔性GN / NaTi ₂（PO ₄）₃ / GN薄膜。柔性膜对钠半电池表现出出色的循环稳定性（在500 mA g ^–1的1000个循环中，91％的容量保持率）。此外，它可以组装成柔性全SIB（Na _0.44 MnO ₂作为阴极）的实际应用。柔性全电池在平坦和弯曲状态下均显示出良好的循环稳定性，与原始容量相比，在平坦状态下的前30个循环后保持92.9％的保持力，在弯曲状态下另外40个循环后保持86％的保持力。该合成途径提供了构建用于SIB的其他柔性膜的通用方法。