This paper highlights our progress in developing pristine single-walled carbon nanotubes (SWCNTs) into functional materials for lightweight, conductive cathodes in lithium air (Li-air) batteries. We outline a process to produce foams of single-walled carbon nanotubes using liquid processing routes that are free of additives or surfactants, using polar solvents and electrophoretic deposition. To accomplish this, SWCNTs are deposited onto sacrificial metal foam templates, and the metal foam is removed to yield a freestanding, all-SWCNT foam material. We couple this material into a cathode for a Li-air battery and demonstrate excellent performance that includes first discharge capacity over 8200 mAh/g, and specific energy density of ∼ 21.2 kWh/kg (carbon) and ∼ 3.3 kWh/kg (full cell). We further compare this to the performance of foams prepared with SWCNTs that are dispersed with surfactant, and our results indicate that surfactant residues completely inhibit the nucleation of stable lithium peroxide materials — a result measured across multiple devices. Comparing to multi-walled carbon nanotubes produced using the same technique indicates a discharge capacity of only ∼ 1500 mAh/g, which is over 5X lower than SWCNTs in the same processing technique and material architecture. Overall, this work highlights SWCNT materials in the absence of impurities introduced during experimental processing as a lightweight and high performance electrode material for lithium-air batteries.
Fluorinated graphene nanoribbons from unzipped single-walled carbon nanotubes for ultrahigh energy density lithium-fluorinated carbon batteries
