Li-air battery system was proposed in 1970s but only had a breakthrough in a non-aqueous system after the report of Abraham and Jiang in 1996. Although Li-air batteries have been recognized as a promising technology from back in the years, they have still several issues in developing practical cells having high energy density (Wh/kg). In particular, it is important to employ a small amount of electrolyte and keep it from escaping cathode during the charge/discharge process. Herein, we developed a free-standing web-like mat cathode comprising composite nanofibers with high CNT loading. The cathode was directly synthesized by an electrospinning process. In order to achieve good electrical conductivity as cathode, high amounts of CNT (ca. 40% of cathode total weight) were simultaneously loaded into nanofibers in the course of electrospinning process, which could be attributed to the utilization of a mixed polymer matrix (PAN and PVP). The domain occupied by PVP was converted to pores after a simple washing process while the remaining PAN domain constructed a backbone of the nanofibers. Polymer fibers, adjacent to CNT particles, can act as an electrolyte reservoir forming continuous path of Li ions. The pores thus formed can promote facile ionic diffusion from electrolyte containing fiber to CNT surface and vice versa. Using this cathode, we successfully prepared a practical cell achieving energy density of 500 Wh/kg by applying optimum electrolyte to cathode ratio. The morphology of nanofibers and the capacity based on CNT of the cathode can be shown in Fig. 1. In this presentation, the morphology of nanofibers composed of CNT and polymers, and their properties as cathode of Li-air cell will be discussed. The battery performances such as capacity and cycle life of Li-air cell will also be described.

Free-standing cathode from locked-in CNTs in as-spun mixed polymer fibers for Li-air batteries

2019 Spring National Meeting

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