Fabrication and performance evaluation of CuO, NiO, and Co3O4- embedded electrospun electrolytes: Suitable for lithium polymer solvent-free batteries

Electrospun fibrous materials are promising electrolytic candidates suitable for all-solid-state lithium batteries (ASSLBs), owning to high ionic conductivity and energy density. However, the limited conductivity is yet to overcome and exploring chemistries for decorating them using electro-active filler of dopants is suggested by experts. In this direction, copper oxide (CuO), nickel oxide (NiO), and cobalt oxide (Co₃O₄) have also gained considerable attention due to their intriguing properties in various electrochemical devices. Herein, nano CuO, NiO, and Co₃O₄ were synthesized and used as the filler in the polyethylene oxide-based electrospun fibers to approach a proper electrochemical behavior. The obtained electrolytes were fully characterized using appropriate analytical systems. Based on the careful analysis of the results, incorporating 0.21 wt% nano CuO into the membrane led to approaching the most desirable characteristics by showing a higher concentration of free Li⁺ ions, greater amorphous domains, and lower Tg. Therefore, the highest ionic conductivity of 0.32 mS cm⁻¹ was achieved at 25 °C. In addition, the CuO-filled fibers resulted in the activation energy drop from 53 to 19 kJ mol⁻¹. The observed trends were confirmed through the estimation of dielectric and electrical properties. In a Li|LiCoO₂ half-cell, reversible CV curves after 25 cycles as well as a stable structure up to 5.00 V were attained for the filled electrospun fibers. More significantly, the presence of CuO nanoparticles caused the discharge capacity increment from 68 to 120 mA h g⁻¹ at 0.5 C for up to 100 cycles. Overall, the upgraded designing of the electrospun fibers through embedding the filler particles opens an influential way toward high-performance ASSLBs with appropriate safety.

Keywords: Electrospun polymer electrolyte All-solid-state lithium battery Copper oxide Nickel oxide Cobalt oxide