Li Guang, Li Tianyu, Jiang Mingchi, Somoro Razium Ali, Sun Ning, Xu Bin
State Key Laboratory of Organic-Inorganic Composites, Beijing Key Laboratory of Electrochemical Process and Technology for Materials, Beijing University of Chemical Technology, Beijing 100029, China.
Shaanxi Key Laboratory of Chemical Reaction Engineering, School of Chemistry and Chemical Engineering, Yan'an University, Yan'an 716000, China.
ACS Appl Mater Interfaces. 2024 Aug 14;16(32):42118-42127. doi: 10.1021/acsami.4c06049. Epub 2024 Aug 2.
Graphite, with abundant resources and low cost, is regarded as a promising anode material for potassium-ion batteries (PIBs). However, because of the large size of potassium ions, the intercalation/deintercalation of potassium between the interlayers of graphite results in its huge volume expansion, leading to poor cycling stability and rate performance. Herein, a self-propagating reduction strategy is adopted to fabricate a flexible, self-supporting 3D porous graphite@reduced graphene oxide (3D-G@rGO) composite film for PIBs. The 3D porous network can not only effectively mitigate the volume expansion in graphite but also provide numerous active sites for potassium storage as well as allow for electrolyte penetration and rapid ion migration. Therefore, compared to the pristine graphite anode, the flexible 3D-G@rGO film electrode exhibits greatly improved K-storage performance with a reversible capacity of 452.8 mAh g at 0.1 C and a capacity retention rate of 80.4% after 100 cycles. It also presents excellent rate capability with a high specific capacity of 139.1 and 94.2 mAh g maintained at 2 and 5 C, respectively. The proposed self-propagating reduction strategy to construct a three-dimensional self-supporting structure is a viable route to improve the structural stability and potassium storage performance of graphite anodes.
石墨资源丰富且成本低廉，被视为钾离子电池（PIB）颇具前景的负极材料。然而，由于钾离子尺寸较大，钾在石墨层间的嵌入/脱嵌会导致其体积大幅膨胀，进而致使循环稳定性和倍率性能较差。在此，采用自蔓延还原策略制备了一种用于钾离子电池的柔性、自支撑三维多孔石墨@还原氧化石墨烯（3D-G@rGO）复合薄膜。三维多孔网络不仅能有效缓解石墨中的体积膨胀，还能为钾存储提供大量活性位点，并允许电解质渗透和离子快速迁移。因此，与原始石墨负极相比，柔性3D-G@rGO薄膜电极展现出大幅提升的钾存储性能，在0.1 C时可逆容量为452.8 mAh g，100次循环后容量保持率为80.4%。它还具有出色的倍率性能，在2 C和5 C时分别保持139.1和94.2 mAh g的高比容量。所提出的构建三维自支撑结构的自蔓延还原策略是提高石墨负极结构稳定性和钾存储性能的可行途径。
