Development of 1 kW h class lithium ion battery for power storage

With the aim of developing 1 kW h class lithium ion batteries with long lif e and high efficiencies, we trial manufactured batteries that were fabricat ed using LiCoO2 and natural graphite as cathode and anode materials, respec tively, with I M LiPF6 diluted by EC/DEC as an electrolyte. Fundamental stu dies necessary for the development of a large-scale battery consisting of l aminated large electrodes were conducted, examining various factors. These factors were selected from the observations of batteries dismantled after t he battery Life reached an end point. The construction of the batteries was based on the results of fundamental research, done to elucidate the proble ms encountered in the present study. We achieved 543 cycles with high effic iencies with the fourth battery. It is noteworthy that technical factor; su ch as homogeneous impregnation of the electrolyte into the electrode lamina tes and maintenance of uniform conditions of laminates by the control of ex pansion and contraction accompanied with charge and discharge, respectively , were very important for the long life of large-scale lithium ion batterie s. (C) 2001 Elsevier Science B.V. All rights reserved.