Synergistic air electrode combining carbon nanotube tissue and fluorinated graphite material in hybrid nonaqueous aluminum batteries

In a typical Al-air battery, the air cathode functions as a deposition substrate for discharge products while allowing O-2 entrance. Herein, we present an air electrode that simultaneously allows two discharge processes. The function of the metal-air battery is enabled by using porous carbon nanotube (CNT)-based tissue substrates. In contrast, the fluorinated graphite (CFx) coating on the CNT substrate provides an additional discharge process, enhancing discharge capacity. Two CFx loadings are investigated, and their performances are compared with that of a pristine CNT tissue. Electrochemical evaluations, including half- and full-cell measurements, are performed to examine the effect of the coating layer thickness on the ability of the cell to function at high discharge rates. High CFx loadings improved the cell performance and increased discharge capacities (an increase of similar to 3 mAh cm(-2) for the 0.1 mA cm(-2) and similar to 5 mAh cm(-2) for the 0.25 mA cm(-2) evaluations) until reaching high discharge loads. When applying 0.5 mA cm(-2), the additional layer restricts O-2 access into the cell, preventing the metal-air battery from functioning as intended. High-resolution scanning electron microscopy and energy-dispersive X-ray spectroscopy are used to characterize the discharge products deposited on this unique electrode.

Automated summary

This study introduces a new air electrode that allows two discharge processes simultaneously, with the use of fluorinated graphite coating on carbon nanotube substrates to enhance battery performance. However, at high discharge loads, the additional layer may restrict oxygen access into the cell.