Freeze-casting preparation of three-dimensional directional porous LiFePO4-graphene composite aerogel for lithium-ion battery

作者：Liu, Zhaofeng; Du, Guodong; Zhou, Yingke^*; Tian, Xiaohui^*

来源：Diamond and Related Materials, 2023, 137: 110074.

DOI：10.1016/j.diamond.2023.110074

• Directional freezing
• Graphene composite aerogel
• Lithium -ion battery
• LiFePO4

An oriented porous three-dimensional LiFePO4-graphene composite aerogel is successfully synthesized using a directional freezing method and applied as the cathode material of lithium-ion battery. The three-dimensional ordered porous structure is formed by the ice crystal template developed in the directional freezing device, which can provide abundant diffusion and transfer channel for electron and lithium ion, and enhance the lithium-ion insertion kinetics. The introduced graphene sheets are evenly embedded into the three-dimensional porous skeleton formed by LiFePO4 particles and are in close contact with the LiFePO4 particles, thus accelerating the electron transfer of the composite. With the graphene content increases, the specific surface area of composite increases, which can afford more active sites for intercalation of lithium ion and enhance the electrolyte/electrode contact area, to improve the energy storage capability of the composites. The optimized directional porous LFP-G composite exhibits high specific discharge capacity (168.2 mAh g-1 at 0.1C), superior rate capability (154.8 and 72.4 mAh g-1 at 1 and 20C) and outstanding cycling stability (98.1 % retention over 800 cycles at 1C). The directional freezing strategy provides a novel way to achieve excellent electrode material for high-performance lithium-ion battery.