Introducing heteroatoms, oxygen vacancies and heterostructures in Co3O4 wrapped in carbon nanofibers by low-temperature vulcanization for lithium-ion storage

Abstract

Co3O4 is considered to be a promising anode material for lithium-ion batteries (LIBs) owing to the high theoretical specific capacity. Nevertheless, its electrochemical performance is not ideal due to structural instability arising from significant volume expansion and poor reaction kinetics. Herein, the electronic structure of Co3O4 is optimized by a one-step low-temperature vulcanization method to form CoO-Co3O4 heterostructures embedded in the carbon nanofibers (CNF, about 400 nm) shell, which is denoted as S-Co3O4-CoO/CNF. The target anode material has rich heterostructure interfaces, oxygen vacancies, and a unique 3D network core-shell structure, which significantly improves the conductivity and reaction kinetics. The improvement has been verified through experimental results and Density Functional Theory (DFT) calculations. As expected, the S-Co3O4-CoO/CNF anode shows excellent rate performance (324.6 mAh g−1 at 10 A/g) and cycling stability (591.2 mAh g−1 after 600 cycles at 1 A/g). Moreover, lithium-ion full cell assembled with LiFePO4 cathode still exhibits good electrochemical performance. Hence, it is expected that the vulcanization method for optimizing electronic structures and constructing heterostructures provides valuable insights for the development of high-performance energy storage materials.