Synthesis of electrochemically active LiCoO 2 and LiNiO 2 at 100 °C

Abstract

Presently, fabrication of LiCoO 2 requires calcination and annealing at temperatures ranging from 850 °C to 1000 °C from one to two days. Herein we show that LiCoO 2 powders can be prepared at temperatures as low as 100 °C through the use of a two days ion exchange reaction between CoOOH and an excess of LiOH · H 2O. The resultant LiCoO 2 powders were studied through the use of X-ray diffraction, thermal gravimetry, and infrared analysis. Low-temperature fabricated LiCoO 2 powders were well crystallized with lattice parameters agreeing with 850 °C prepared samples. The samples had an infrared spectrum similar to that of LiCoO 2 with, however, weak extra lines indicating the presence of both carbonate and hydroxyl species. The presence of these species was found to severely affect both the capacity and reversibility of the electrochemical intercalation reactions. Heating these powders at moderate temperatures, around 250 °C, was effective in removing the species and drastically improving their electrochemical cycling properties. The same ion exchange reaction was successfully applied to the synthesis of LiNiO 2.