Impact of Carbonization Temperature on the Structure and Li Deposition Behavior of 3D Dual Metal Carbon Fibers

Li deposition within lithiophilic-lithiophobic metal carbon fibers is influenced by several structural factors, including electrical conductivity, surface-bound functional groups, particle size and distribution of the lithiophilic-lithiophobic components, which are significantly affected by the carbonization temperature. To gain a deeper understanding of how these different parameters affect the Li deposition behavior, a detailed analysis of Ag and Cu containing carbon fibers at carbonization temperatures from 500 to 1000 degrees C is performed. At lower carbonization temperatures, the fibers exhibit an unordered carbon structure with a high concentration of heteroatoms and a lithiophilic-lithiophobic gradient. However, the high electrical resistance at these temperatures impedes Li-ion interaction with the fibers, leading to the formation of mossy and dead Li. In contrast, higher carbonization temperatures result in the removal of heteroatoms and a more ordered carbon structure. The agglomeration of Cu and Ag particles at these temperatures disrupts the lithiophilic-lithiophobic gradient, causing concentrated Li deposition on top of the fibers. A threshold temperature of 700 degrees C has been identified for achieving homogeneous Li deposition. At this temperature, the lithiophilic-lithiophobic gradient still exists, and the more ordered carbon structure enhances Li-ion interaction with the fibers, resulting in stable Li deposition for over 1100 h. A detailed investigation of the structural evolution of 3D lithiophilic (Ag)-lithiophobic (Cu) carbon fibers at different carbonization temperatures and the corresponding correlation between the structural features and Li deposition is performed. Particular emphasis is placed on understanding how changes in the carbon structure, along with the size and distribution of the metal particles, influence the Li deposition behavior.image (c) 2024 WILEY-VCH GmbH