Effect of the inorganic filler on the electrochemical properties of the polymer electrolytes

Abstract

The goal of the research in this thesis is to extend the understanding of the physics involved in the electrochemical characteristics of the polymer electrolytes including silica and to develop the novel composite polymer electrolytes(CPE) applicable to lithium polymer batteries (LPB). The important challenge in lithium battery technology are the replacement of the carbonaceous anode by a lithium metal anode and of the liquid electrolyte by a polymer one, i.e., going from a liquid lithium-ion battery to a solid “lithium polymer battery” (LPB). These developments are in turn expected to result in a further improvement of energy density and to enable a plastic configuration for enhanced versatility in battery design and reduced manufacturing costs. These traits are particularly appealing for electric vehicle applications, whence the intensive LPB studies currently underway at various industrial and academic laboratories. The main requisite for success in LPB development is the optimization and control of the electrode/polymer electrolyte interface. This is indeed the requirement which poses the main problems, especially as regards the reactivity of the lithium metal to the polymer electrolyte, which can lead to uncontrolled passivation phenomena with the formation of surface layers. Thick, passivation-induced layers cause uneven lithium deposition in the charge process, thereby resulting in dendritic growth and eventual cell short-circuiting. Of paramount importance is to control the growth of passivation layers so as to attain protection against further lithium corrosion and to assure an efficient lithium deposition-stripping process. It is now well established that the type and growth of the lithium passivation layer is unpredictably influenced by the presence of liquid components and/or impurities in the electrolytes. The liquid phase decomposes at the surface of lithium, thereby severely affecting the cyclability of the lithium electrode. One obvious approa...