Functional carbon nanofibers prepared by electrospinning as free-standing electrodes for Lithium-Sulfur batteries

Lithium-sulfur (Li−S) batteries have emerged as one of the most promising alternatives to commercial Li-ion batteries. However, their development has been hampered by low Coulombic efficiency, rapid capacity fading, and safety concerns associated with the lithium metal anode. This thesis focuses on the construction of functional carbon nanofibers prepared by electrospinning as free-standing electrodes for Li−S batteries. These carbon nanofibers were synthesized by calcination of various electrospun polymer nanofibers (polyvinylpyrrolidone and lignin nanofibers) in an inert gas, which can be directly used as electrodes without additional binders or conductive carbon. Meanwhile, the carbon nanofibers were functionalized with hybrid materials (e.g., oxygen-deficient titanium dioxide, molybdenum disulfide, and phosphorus doping) to suppress the shuttle effect of lithium polysulfides (LiPSs) in Li−S batteries. Their interactions with LiPSs in the cathode have been comprehensively investigated in the following three parts. The influence of phosphorus-doped carbon nanofibers on Li deposition in the anode has also been investigated in the third part.