Lithium Ion Capacity of Single Wall Carbon Nanotube Paper Electrodes

Abstract

The electrochemical cycling performance of high purity single wall carbon nanotube (SWCNT) paper electrodes has been measured vs lithium metal for a series of electrolyte solvent compositions. The addition of propylene carbonate (PC) into the conventional ethylene carbonate (EC):dimethyl carbonate (DMC) cosolvent mixture enabled a reversible lithium ion capacity of 520 mAh/g for high purity SWCNTs. The free-standing SWCNT electrode (absent of polymer binder or metal substrate support) with this electrolyte combination demonstrates enhanced cycleability, retaining >95% of the initial capacity after 10 cycles. The first cycle hysteresis, common in these materials, is shown to vary dramatically with solvent selection and illustrates the importance of the solid−electrolyte−interface (SEI) formation on SWCNT capacity. The effect of galvanostatic charge rate (i.e., C-rate) on lithium ion capacity shows a 2× improvement [in capacity per current] over reported values for conventional graphite anode materials. The...