CAMP March Newsletter: Page 7
CAMP Professor Dipankar Roy Studies Different Aspects of Materials Engineering for Advanced Lithium Ion Batteries
CAMP Professor Dipankar Roy and his group are studying different aspects of materials engineering for advanced lithium ion batteries. A major performance-limiting factor for lithium ion batteries is the cathode that determines the capacity, operational voltage, charge-discharge rates, and energy density. The carbon-based anodes traditionally used in these batteries exhibit relatively slow charging. Many new applications of these batteries also require safe and efficient operation over a wide temperature range, for which the flammable and volatile carbonate electrolytes alone are not adequate. In addition, if the cathode reacts with the electrolyte, the cycle life of the battery becomes rather limited. Professor Roy’s group is studying these different aspects of materials engineering for advanced lithium ion batteries. They are focusing on ceramic cathodes and electrochemically fabricated transition metal oxides for anodes. These materials are attractive for pulse-power applications (e.g., HEVs) and large-scale energy storage (e.g., solar storage). The CAMP group also studies electrolytes based on room temperature ionic liquids (ILs) that can significantly reduce the utilization of volatile/flammable solvents.
Illustrative results of electrolyte engineering in Roy’s group are shown in Figure 11 in the form of Ragone plots using an IL-incorporated solution. The plots demonstrate how the performance of the battery at an elevated temperature is improved over the corresponding room temperature case. Further experiments using anode materials other than Li are currently underway. More information about Professor Roy’s research can be found at http://people.clarkson.edu/~samoy/cr_projects.htm.
FIGURE 11: Ragone plots for a Li (anode) | LiMn2O4 (cathode) cell. The gravimetric energy and power correspond to the active material mass of the cathode. Commercially available LiMn2O4 was used to fabricate the cathode, and the electrolyte included LiBF4 dissolved in carbonate solvents. The numbers associated with each straight line (marking power density regimes) indicate the total time and C-rate of discharge. The more a Ragone plot moves toward the upper right corner, the better is the battery performance.