Electrochemical properties of electrospun CuxO (x = 1, 2)-embedded carbon nanofiber with EXAFS analysis

The CuxO (x = 1, 2)-embedded carbon nanofibers (CuxO/CNF) were prepared by electrospinning of the composite solutions of Cu(II) acetate, PAN (polyacrylonitrile) and PVP (polyvinylpyrrolidone), and subsequent stabilization and carbonization. The structure of Cu2O/CNF is largely dependent on the carbonization temperature. The CuxO/CNF-700 has the disordered CuO structure, while the CuxO/CNF-800 has the intermediate structure between the disordered CuO and Cu2O. The structural change in the CNF prepared by electrospinning and optimum thermal treatment leads to excellent electrochemical properties. The CNF plays an important role as buffering agent to prevent CuxO particles from agglomerating. Besides, the aligned CNF with high electrical conductivity leads to the occurrence of Cu nano-particles in the discharging process, and it serves to convert Li2O into Li in the charging process. Both CuxO/CNF-700 and CuxO/CNF-800 exhibit high specific discharge capacity, exceptional cycle retention, and excellent reversible capacity even in initial cycle, while CuxO/CNF-900 shows bad electrochemical performance.

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► Electrospun CuxO-embedded carbon nanofiber (CuxO/CNF) represents the outstanding electrochemical performance as anode materials for LIB.
► Fine structure of CuxO in carbon nanofiber is scrutinized by EXAFS.
► For CuxO/CNF-800, the CuxO has intermediate structure between the disordered CuO and Cu2O.
► The coulomb efficiency and specific discharge capacity of CuxO/CNF-800 exhibit 75% at 1st cycle and 464 mAh g−1 at 100th cycle, respectively.