Coupling effect of the conductivities of Li ions and electrons by introducing LLTO@C fibers in the LiNi0.8Co0.15Al0.05O2 cathode

• 作者: Hao-yang Wang Xue Cheng Xiao-feng Li Ji-min Pan Jun-hua Hu
• 来源期刊: 矿物冶金与材料学报
• 年，卷（期）: 2021,（2）
• 页码范围: 305-316
• 页数: 12页
• 语种: 英文

摘要

To probe the coupling effect of the electron and Li ion conductivities in Ni-rich layered materials (LiNi0.8Co0.15Al0.05O2, NCA), lithi-um lanthanum titanate (LLTO) nanofiber and carbon-coated LLTO fiber (LLTO@C) materials were introduced to polyvinylidene difluoride in a cathode. The enhancement of the conductivity was indicated by the suppressed impedance and polarization. At 1 and 5 C, the cathodes with coupling conductive paths had a more stable cycling performance. The coupling mechanism was analyzed based on the chemical state and structure evolution of NCA after cycling for 200 cycles at 5 C. In the pristine cathode, the propagation of lattice damaged regions, which con-sist of high-density edge-dislocation walls, destroyed the bulk integrity of NCA. In addition, the formation of a rock-salt phase on the surface of NCA caused a capacity loss. In contrast, in the LLTO@C modified cathode, although the formation of dislocation-driven atomic lattice broken regions and cation mixing occurred, they were limited to a scale of several atoms, which retarded the generation of the rock-salt phase and res-ulted in a pre-eminent capacity retention. Only NiO phase"pitting"occurred. A mechanism based on the synergistic transport of Li ions and electrons was proposed.