Abstract Potassium-ion batteries (KIBs) have been regarded as prospective energy storage system due to the rich reserves and affordable price of potassium resources. However, the lack of high-capacity electrode materials still inhibits the further development of KIBs. Here, we report a unique hollow metallic Co0.85Se cubes encapsulated in graphene (Co0.85Se/G) for KIBs anode. The unique hollow structure features high surface area that guarantees Co0.85Se enough contact with electrolyte. The graphene wrapping blocks the agglomeration and relieves the volume changes of Co0.85Se. The metallic property of Co0.85Se and high conductivity of graphene can boost the rate performance. As a consequence, Co0.85Se/G delivers a high capacity of 324 mAh g−1 at 50 mA g−1 over 200 cycles, and the capacity can be kept at 213 mAh g−1 even at of 1000 mA g−1 over 1000 cycles.

中文翻译：

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封装在石墨烯中的空心 Co0.85Se 立方体以增强钾的储存

摘要 钾离子电池（KIBs）由于钾资源储量丰富且价格合理，被认为是具有前景的储能系统。然而，高容量电极材料的缺乏仍然阻碍了KIBs的进一步发展。在这里，我们报告了一种独特的空心金属 Co0.85Se 立方体，封装在石墨烯 (Co0.85Se/G) 中，用于 KIBs 阳极。独特的中空结构具有高表面积，可确保 Co0.85Se 与电解质充分接触。石墨烯包裹阻止了团聚并缓解了 Co0.85Se 的体积变化。Co0.85Se 的金属特性和石墨烯的高导电性可以提高倍率性能。因此，Co0.85Se/G 在 50 mA g-1 下在 200 次循环中提供了 324 mAh g-1 的高容量，