Progress towards high-power Li/CFx batteries: electrode architectures using carbon nanotubes with CFx

Abstract

Carbon monofluoride (CF_x) has a high energy density, exceeding 2000 W h kg⁻¹, yet its application in primary lithium batteries is limited by its power capability. Multi-walled carbon nanotubes (CNTs) are appealing additives for high-power batteries, due to their outstanding electronic transport properties, high aspect ratio necessitating low volume fraction for percolation, and high tensile strength. This perspective describes the current state of the art in lithium–carbon monofluoride (Li/CF_x) batteries and highlights the opportunities for the development of high-power Li/CF_x batteries via utilization of carbon nanotubes. In this report, we generated several electrode architectures using CF_x/CNT combinations, and demonstrated the effectiveness of CNTs in enhancing the rate capability and energy density of Li/CF_x batteries. First, we investigated the resistivity of CF_x combined with CNTs and compared the CF_x/CNT composites with conventional carbon additives. Second, we built CF_x–CNT electrodes without metallic current collectors using CNTs as substrates, and compared their electrochemical performance with conventional CF_x electrodes using aluminum foil as a current collector. Furthermore, we fabricated multi-layered CNT–CF_x–CNT composite electrodes (sandwich electrodes) and studied the impact of the structure on the performance of the electrode. Our work demonstrates some of the opportunities for utilization of CNTs in CF_x electrodes and the resultant implementation of CF_x as a battery cathode in next-generation high-power batteries.