|Initial Investigations on the Use of Coated Nano-Sized Phthalocyanines for Very High Energy Density Rechargeable Lithium-Based Batteries Progress in Cathodes VII
The FePc cells consisted of lithium metal foil as the anode (149 µm thick, 0.970 cm2 cross-sectional area), Celgard with a 1.0 M solution of LiPF6 in ethylene carbonate/dimethyl carbonate (1:1 vol% ratio) electrolyte. and the cathode consisted of 60:30:10 wt% C-FePc, CNT, PEO binder, respectively (~90 µm thick, 1.267 cm2cross-sectional area).
Nano-sized FePc particles were prepared by placing FePc powder, from Aldrich, into a SPEX SamplePrep model 8003 alumina grinding vial with an ½" diameter alumina grinding ball. The jar was then placed inside a SPEX SamplePrep 8000M Mixer/Mill for 200 minutes. A TEM was then used to verify the size of the particles as approximately 25-50 nm; significantly smaller than the 1-2 um size when originally purchased.
The nano-sized FePc particles were then encapsulated with carbon. This was done by mixing the nano-sized FePc and malic acid in a 1:2 wt% ratio in a Pyrex vial and then adding a small amount of toluene to create a slurry. A magnetic stir bar was then placed in the mixture and the slurry was stirred for 2 hours on a stir plate. The vial was then placed inside a vacuum oven, heated to 180 °C, and dried overnight under vacuum and at temperature to form the carbon coated FePc particles.
The CNT particles were prepared by an AFRL in-house procedure to be disclosed in the full paper.
A Hohsen 2032 coin cell crimping machine was used to make the coin cells. All procedures for the making of the coin cells were performed in a dry room with a dew point temperature of ~-40 oC. The coin cells were cycled using a Maccor 3600 system and AC impedance spectroscopy was performed using a Gamry 3000 system.