Fractal Electrodes for Lithium-Ion Batteries
Creators: name: University Of California Office Of The President
Publisher: name: University of California Office of the President
publisherIdentifier: https://ror.org/00dmfq477
publisherIdentifierScheme: ROR
Year: 2024

description: In recent years, hybrid electric vehicles (HEVs) have emerged as the most viable alternative propulsion system amidst growing environmental concerns. The electrical energy storage system is a key component in the HEV, and the lithium-ion battery is expected to be an attractive storage device owing to its high energy and power density as compared to the commercialized nickel-metal hydride battery (NiMH). In order to use lithium-ion batteries in automotive applications, one key factor is the development of high-performance electrodes. Even though a major research effort is being directed to the use of nano-scale materials in battery electrodes (i.e., nanopowders), this approach is not optimal. Disadvantages include an increase in undesirable electrode/electrolyte reactions due to high surface area, leading to self-discharge, poor cycling and short life. Additionally, inferior packing of particles leads to lower volumetric energy densities. To improve their performance, aside from a larger surface area and small particle size, the electrodes need to have an optimum microstructural architecture to allow for efficient charge transfer leading to enhanced electrochemical activity. Here we propose to develop fractal electrode structures for lithium-ion batteries. Fractals are ubiquitous in nature and are especially efficient in the exchange and transport of mass and energy. They also provide a middle ground between high-surface-area electrodes comprised of nanomaterials and solid electrodes: they offer a large area of contact at their interface while keeping a continuous path for charge transport . Our multi-disciplinary approach involves theoretical/computational modeling, experimental diagnostics and fabrication techniques towards a completely new type of three-dimensional electrodes with fractal properties. The computational model will comprise of a multi-physical, multi-scale model for species and charge transport along with electrochemical reaction for optimizing electrode structures for enhanced performance. The fractal structures will be synthesized by integrating micro- and nano-fabrication techniques using a combination of bottom-up and top-down approaches. The tasks to be performed during the development of this project are: 1. Modeling and optimization of the behavior and performance of fractal-like carbon electrodes through computational methods (multi-scale modeling approach). 2. Integration of top-down and bottom-up fabrication techniques in order to create structures that span over 6 or more orders of magnitude in dimension in a fractal-like arrangement. 3. Characterization and evaluation of the performance of the fractal electrodes, measurement of their fractal dimensions and assembling of complete lithium-ion cells for characterization. 4. Applicability of the new fractal electrodes to automotive applications (scaling up into HEV-sized battery) The collaboration builds on the complimentary expertise of the collaborating investigators at LANL (modeling of electrochemical energy systems) and UCI (fabrication and testing of battery electrodes). Professor Marc Madou (PI) is an expert in microfabrication techniques and electrochemical diagnostics. Dr. Partha P. Mukherjee and Dr. Qinjun Kang (co-PI’s) from LANL have extensive expertise in multi-physics, multi-scale modeling involving multicomponent, reactive transport in porous media and electrochemical energy systems. The LANL researchers will benefit by integrating experimental measurements with the theoretical/modeling predictions, while the research team from UC Irvine will develop theoretical/modeling capability by working closely with LANL researchers. Two graduate students will be involved each year during the development of this project. They will perform both experimental and theoretical work, and will collaborate extensively with the investigators at the LANL. Furthermore, this proposal relates to the following energy security areas, which are part of the Los Alamos National Lab’s energy security goal: 1. Diversify our energy mix and reduce dependence on foreign petroleum, thereby reducing vulnerability to disruption and increasing the flexibility of the market to meet U.S. needs 2. Reduce greenhouse gas emissions and other environmental impacts (water use, land use, criteria pollutants) from our energy production and use 3. Improve the energy productivity (or energy efficiency) of the U.S. economy.