Effect of calendering on rate performance of Li4Ti5O12 anodes for lithium-ion batteries

Lithium titanate (LTO) anodes despite their low specific capacity of 175 mAhg(-1) from a low volume change and intercalation voltage of 1.55 V vs lithium are excellent for automotive applications requiring fast and safe charging at times like regenerative braking. The present study focuses exclusively on the effect of calendering on the charging rate of LTO anodes. Calendering is a process where the current collector coated with the electrode, both anode, and the cathode is passed between two rolls at an elevated temperature to compact and improve the electrode's energy density and electrochemical performance. The anode, LTO coated on aluminum foil current collector, calendered at about 42% (i.e. reducing the thickness of uncalendered anode from similar to 175 to similar to 100 mu m) showed exceptional capacity retention even at 10C rate. Rate performance analyses reveal that calendering improves the capacity at high C-rate, whereas it doesn't impact significantly at low C-rate. Electrochemical impedance spectroscopy measurements show that the resistive losses decrease with calendering.