Research and Development Work on Lithium-ion Batteries for Enviromental Vehicles

In the first stage of our research and development work on high-performance lithium-ion batteries from the early to the mid-1990s, a high-energy-capacity battery was investigated with the aim of applying it to electric vehicles (EVs). The second stage of our program concerned studies of a lithium-ion battery for application to series hybrid electric vehicles (SHEVs), and the third stage was mainly focused on a high- power lithium-ion battery for use on parallel hybrids (PHEVs). The results of those studies demonstrated that lithium-ion batteries are the best battery systems for use on these environmental vehicles. A battery simulation program was also constructed concurrently with those investigations for use as a tool in verifying the superiority of lithium-ion batteries. This simulation program takes into account the electrochemical phenomena that occur inside the battery, especially the effect of lithium-ion diffusion on power output characteristics. In the present study, battery simulations were performed to quantify the flow of ions inside the battery. This paper presents the results of sensitivity analyses concerning the electrode structural parameters influencing the long-duration power output characteristic that is required of batteries for use on EVs and SHEVs.