Synthesis and characterization of new cathode material for Lithium - ion batteries

TERNY, S.; DE LA RUBIA M; DE FRUTOS VAQUERIZO, J.; FRECHERO M. A.

Conferencia; 14 International Conference European Ceramic Society; 2015

Energy is of central importance in the evolution of human societies. Fossil fuels like oil, coal, and natural gas are nature?s ancient energy resources. The continued combustion of non-renewable fossil fuels, however, is not only hastening the depletion of resources, but is also increasingly worsening global warming and environmental issues. Consequently, energy alternatives, such as solar, wind, hydropower, and geothermal, are emerging. Although these energy resources are renewable, cost-effective and clean, some of them significantly rely on natural conditions (e.g., sunshine, rain, wind, location, etc.) and thus are not reliable which restrict their wide spread usage. Energy storage thus becomes even more important and has received worldwide attention. Converting into chemical energy is the most convenient form to store energy. Rechargeable (or secondary) batteries are the most successful energy storage devices that convert off-peak electricity into chemical energy and release the stored energy reversely during the on-peak period. Lithium-ion batteries (LIBs) with various shapes (e.g., coin, cylindrical, prismatic, or stack, etc.) are the dominant power sources in today?s information-rich, mobile society to power numerous portable consumer electronics (e.g., smartphones, tablets, notebook PCs, and camcorders, etc.) and even as a vital component in new hybrid electric vehicles. The motivation for using a LIB relies on its high energy density (both volumetric and gravimetric), low self discharge rate, wide operating temperature range, no voltage depression (i.e., ?memory effect?) and environmental friendliness. There is a growing interest in developing high capacity cathode materials to power large-scale systems. Moreover, cathodes have a significant impact on the cell voltage, charge transfer kinetic, safety, and cost. Therefore, the developments of cathode materials have become extremely important. There are exciting developments in new positive electrode (cathode) materials to replace the LiCoO2 for use in the LIBs over the past decade. Monoclinic Li3V2(PO4)3 (LVP) with promising electrochemical properties including excellent cycling stability, high theoretical capacity (197 mAh g-1), low synthetic cost, improved safety characteristic, and low environmental impact emerges as highly suitable candidate. The main objective of this work is the synthesis and characterization of new cathode materials of general composition: The new materials presented here will be doped with two transition metal ions (TM: Cu2+ and Nb5+); ion-doping is an efficient method to improve the intrinsic electronic conductivity and Li-ion diffusion. On the other hand, these materials will be coated with CNF (carbon nano fibers) as carbon source. Coating of the LVP particle surface with amorphous carbon is the most common way to enhance its electronic conductivity so that the active materials can be largely utilized at high current rates. Carbon coating can also improve the growing up and aggregation of LVP particles during the high temperature calcinations. Additionally, carbon can act as reducing agent to reduce V5+ to V3+ and thus simplify the atmosphere requirement in the synthesis. These materials will be characterized structural and electrically by SEM, TEM, EIS and Confocal Raman spectroscopy.