Li-Air Thin Film Energy Storage Devices: Materials Development and Integration
Professor Ernesto E. Marinero
Schools of Chemical and Materials Engineering, Purdue University, Neil Armstrong Hall of Engineering, West Lafayette, Indiana, USA; firstname.lastname@example.org
The need for higher energy capacity, portable, wearable and implantable devices has enormously incremented in recent years. Additional functionality and thus, enhanced energy consumption characterizes the development of new generations of portable devices. Whereas evolutionary improvements in energy density can be anticipated in Li-ion technology, the most advanced portable battery devices currently in the market, its chemistry, limits the attainable capacity in such devices. Alternative lithium-air battery systems provide a theoretical energy density rivaling that of liquid fuels.
There remains however significant technical challenges to be solved for the realization of safe, fully recyclable, high-energy capacity Li-Air batteries. These include, the reactivity of high capacity Li metal anodes, the propensity for incremental dendrite formation when employing said anodes with state-of-the-art liquid and polymer electrolytes. In addition, during cycling of rechargeable lithium-ion cells, lithium can buildup in the electrolyte, resulting in thermal runoff, rapid discharge, ultimately failure of the cell. Engineering an electrolyte to better interface with lithium metal and easily cycle lithium ions, is essential for making Li-air technology a reality. The realization of Li-Air batteries have been equally hindered by the lack of an Air-cathode capable of providing the multi-functionality required for device operation. This include a cathode microstructure that accommodates solid state oxide and peroxide Lithium reaction products while providing adequate transport of oxygen and Li toward the active, electron conducting surfaces; the development of oxygen resistant cathode materials that are impervious to high oxidation potentials and the implementation of an efficient redox process at the cathode surface in a way that lithium oxidation is fully reversible. Solving these challenges will provide solutions to key technical barriers for the implementation of Li-Air technology, which include limited cyclability, in particular at high current densities, excessive fading, charge and discharge over potentials and temperature dependent effects.
The goal of this project is the rational design and synthesis of materials and energy storage device components through thin film growth techniques to engineer the microstructure, the stoichiometry and the functionality of solid-state electrolytes and air-cathode structures for Li-Air thin film batteries. Materials properties such as crystalline phase, grain size, growth orientation, lattice parameters and stress will be manipulated to develop solid state electrolytes whose Li-ionic conductivity is on par liquid phase electrolytes. The multi-functional characteristics of the air-cathode will be addressed through co-deposition, multilayered and laminated of for example nanoporous carbon thin films with judiciously chosen catalytic nanoparticles and/or thin films. Property optimization of the solid state electrolytes and the air-cathode materials will be bench-marked against state-of-the art electrolytes and cathode components utilizing industry standard tests and methodologies. In parallel we will conduct extensive materials characterization studies of solid-state electrolyte and air-cathode materials for additional functionality improvements based on fundamental understanding. These optimized components will be integrated into battery devices which will be in turn be tested and benchmarked against state-of-the-art battery devices with the same form factor.