As one of prussian blue analogues, Co₃[Co(CN)₆]₂ has been explored as a promising anode material for potassium-ion batteries (PIBs) owing to its high potassium storage capacity. Unfortunately, Co₃[Co(CN)₆]₂ possesses low electronic conductivity and its structure collapses easily during potassiation and depotassiation, resulting in poor rate performance and cyclic stability. To solve these problems, we develop a facile multi-step method to successfully combine uniform Co₃[Co(CN)₆]₂ nanocubes with rGO by C−O−Co bonds. As expected, these chemcial bonds shorten the distance between Co₃[Co(CN)₆]₂ and rGO to the angstrom meter level, which significantly improve the electronic conductivity of Co₃[Co(CN)₆]₂. Besides, the complete encapsulation of Co₃[Co(CN)₆]₂ nanocubes by rGO endows the structure of Co₃[Co(CN)₆]₂ with high stability, thus withstanding repeated insertion/extraction of potassium-ions without visible morphological and structural changes. Benefiting from the above-mentioned structural advantages, the Co₃[Co(CN)₆]₂/rGO nanocomposite exhibits a high reversible capacity of 400.8 mAh g⁻¹ at a current density of 0.1 A g⁻¹, an exceptional rate capability of 115.5 mAh g⁻¹ at 5 A g⁻¹, and an ultralong cycle life of 231.9 mAh g⁻¹ at 0.1 A g⁻¹ after 1000 cycles. Additionally, the effects of different amounts of rGO and different sizes of Co₃[Co(CN)₆]₂ nanocubes on the potassium storage performance are also studied. This work offers an ideal route to significantly enhance the electrochemical properties of prussian blue analogues.

作为普鲁士蓝的类似物之一，由于其高的钾存储能力，已将Co ₃ [Co（CN）₆ ] ₂作为有前景的钾离子电池负极材料进行了研究。不幸的是，Co ₃ [Co（CN）₆ ] ₂具有低电子电导率，并且在钾化和去钾化过程中其结构容易崩溃，导致差的速率性能和循环稳定性。为了解决这些问题，我们开发了一种简便的多步方法，通过C-O-Co键成功地将均匀的Co ₃ [Co（CN）₆ ] ₂纳米立方体与rGO结合。不出所料，这些化学键缩短了Co ₃之间的距离[Co（CN）₆ ] ₂和rGO达到埃米级，可显着提高Co ₃ [Co（CN）₆ ] ₂的电子电导率。此外，rGO完全包裹了Co ₃ [Co（CN）₆ ] ₂纳米立方体，使得Co ₃ [Co（CN）₆ ] _2的结构具有很高的稳定性，因此可以经受钾离子的反复插入/提取而没有明显的形态和结构变化。受益于上述结构优势，Co ₃ [Co（CN）₆ ] ₂/ rGO纳米复合材料在0.1 A g ^-1的电流密度下显示出400.8 mAh g ^-1的高可逆容量，在5 A g ^-1时显示出115.5 mAh g ^-1的出色倍率容量，以及231.9 mAh的超长循环寿命克^-1在0.1 A克^-1 1000次循环之后。此外，还研究了不同量的rGO和不同大小的Co ₃ [Co（CN）₆ ] ₂纳米立方体对钾存储性能的影响。这项工作提供了一条理想的途径，可以显着增强普鲁士蓝类似物的电化学性能。