Na‐Se and K‐Se batteries are attractive as a stationary energy storage system because of much abundant resources of Na and K in the Earth's crust. As the alloy‐type Se has a severe pulverization issue, one critical challenge to develop advanced Na‐Se and K‐Se batteries is to explore a highly efficient and stable Se‐based cathode. Herein, a flexible free‐standing Se/carbon composite film is prepared by encapsulation of Se into a carbon nanotube (CNT) interwoven N,O dual‐doped porous carbon nanosheet (Se@NOPC‐CNT). The 3D interconnected CNT uniformly wrapped on the N,O dual‐doped porous carbon skeletons improves the flexibility and offers an interconnected conductive pathway for rapid ionic/electronic transport. In addition, the N,O dual‐doping significantly enhances the chemical affinity and adhesion between Na_xSe/K_xSe (0 < x ≤ 2) and porous carbon, which is confirmed by density functional theory calculation. When used as the cathode in Na‐Se batteries, the Se@NOPC‐CNT delivers a remarkable reversible capacity of 400 mA h g⁻¹ at 1 A g⁻¹ after 2000 cycles with a 0.008% capacity decay per cycle. For K‐Se batteries, it also exhibits an excellent cycling stability (335 mA h g⁻¹ after 700 cycles at 0.8 A g⁻¹). This unique design may open an avenue for practical application of flexible Na‐Se and K‐Se batteries.

中文翻译：

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碳纳米管交织的氮和氧双掺杂多孔碳纳米片作为用于高性能Na-Se和K-Se柔性电池的自由电极

Na-Se和K-Se电池作为固定式储能系统具有吸引力，因为地壳中Na和K的资源非常丰富。由于合金型Se存在严重的粉碎问题，因此开发高级Na-Se和K-Se电池的一项关键挑战是探索一种高效且稳定的Se基阴极。在此，通过将Se封装到碳纳米管（CNT）交织的N，O双掺杂多孔碳纳米片（Se @ NOPC-CNT）中来制备柔性的自立式Se /碳复合膜。均匀包裹在N，O双掺杂多孔碳骨架上的3D互连CNT改善了柔韧性，并提供了互连的导电路径，可快速进行离子/电子传输。此外，N，O双掺杂显着增强了Na _x之间的化学亲和力和附着力Se / K _x Se（0 < x≤2）和多孔碳，这通过密度泛函理论计算得到了证实。当用作Na-Se电池的阴极时，Se @ NOPC-CNT在2000次循环后在1 A g ^-1下可提供400 mA hg ^-1的显着可逆容量，每循环0.008％的容量衰减。对于K硒电池，它也显示出优异的循环稳定性（335毫安汞柱^-1在0.8 A克700次循环后^-1）。这种独特的设计可能为柔性Na-Se和K-Se电池的实际应用开辟一条道路。