Advancements in Li/LiCoO2 hardware cell performance, safety and reliability

A general review of the Li/LiCoO₂ electrochemistry is presented along with a summary of the component and design analyses that have supported the development of the hardware cells. The authors cover various details on charging parameters, storage capabilities, cycle life as related to depth-of-discharge, varying discharge profiles, peak power limits, series cell testing. etc. Component variables that were evaluated included cathode densities and thicknesses, separator layers and types, cathode processing techniques, electrolyte molarity and volume, and other construction details. The Li/LiCoO₂ system has been significantly advanced through recent prototype production lot build and test programs of standard D size rechargeable cells. Performance criteria such as energy density, voltage level, rate capability, and charging efficiency have been demonstrated to be superior in practical hardware to most competing technologies. Storage characteristics and cycling capacity are comparable to many other rechargeables. Methods for increasing cycling efficiency to better achieve expected cycle life at full capacity have also been identified. D cells with 5 Ah capacity for over 50 cycles at a 2 A discharge rate are practical