Zheng Hui, Xu Han-Shu, Hu Jiaping, Liu Huimin, Wei Lianwei, Wu Shusheng, Li Jin, Huang Yuhu, Tang Kaibin
Department of Chemistry, University of Science and Technology of China Hefei 230026 People's Republic of China.
Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China Hefei 230026 People's Republic of China
RSC Adv. 2022 Aug 2;12(33):21374-21384. doi: 10.1039/d2ra03608h. eCollection 2022 Jul 21.
Potassium-ion batteries (PIBs) have received much attention as next-generation energy storage systems because of their abundance, low cost, and slightly lower standard redox potential than lithium-ion batteries (LIBs). Nevertheless, they still face great challenges in the design of the best electrode materials for applications. Herein, we have successfully synthesized nano-sized CoSe encapsulated by N-doped reduced graphene oxide (denoted as CoSe@N-rGO) by a direct one-step hydrothermal method, including both orthorhombic and cubic CoSe phases. The CoSe@N-rGO anodes exhibit a high reversible capacity of 599.3 mA h g at 0.05 A g in the initial cycle, and in particular, they also exhibit a cycling stability of 421 mA h g after 100 cycles at 0.2 A g. Density functional theory (DFT) calculations show that CoSe with N-doped carbon can greatly accelerate electron transfer and enhance the rate performance. In addition, the intrinsic causes of the higher electrochemical performance of orthorhombic CoSe than that of cubic CoSe are also discussed.
钾离子电池（PIBs）因其储量丰富、成本低廉且标准氧化还原电位略低于锂离子电池（LIBs），作为下一代储能系统受到了广泛关注。然而，在设计适用于该应用的最佳电极材料方面，它们仍然面临巨大挑战。在此，我们通过直接一步水热法成功合成了由氮掺杂还原氧化石墨烯包裹的纳米级CoSe（表示为CoSe@N-rGO），其中包括正交相和立方相的CoSe。CoSe@N-rGO阳极在初始循环中于0.05 A g时表现出599.3 mA h g的高可逆容量，特别是在0.2 A g下循环100次后，它们还表现出421 mA h g的循环稳定性。密度泛函理论（DFT）计算表明，氮掺杂碳的CoSe可以极大地加速电子转移并提高倍率性能。此外，还讨论了正交相CoSe比立方相CoSe具有更高电化学性能的内在原因。
