Performance improvement of hybrid electrolyte technology batteries for electrical propulsion in aerospace industry
Creators: name: AYERBE, Elixabete
name: VARAS, Fernando
Publisher: name: Proceedings of the 8th European Conference for Aeronautics and Space Sciences. Madrid, Spain, 1-4 july 2019
Year: 2019
Subjects: ELECTRIC PROPULSION

description: In the aerospace industry, electrical propulsion promises to completely revolutionize the industry, with brand new architectures and ecosystems becoming tomorrow\'s reality. High storage capacity and low weight batteries are clearly crucial to all-electric and hybrid-electric aircrafts, and in order to begin to allow the reaction of products with commercially viable payload-range characteristics, it is generally accepted that electrical storage systems would need an energy density of at least 500 Wh/kg after 2025.6 Currently, the battery market is dominated by conventional Li-ion technology (LIB), which is reaching its theoretical limits (300 Wh/kg). Hybrid electrolyte with metallic lithium and Ni-rich cathode batteries are among the most promising candidates due to their many advantages, such as high specific energy density, high operating voltage, low self-discharge rate and no memory effect. However improvement of performance must be achieved through the optimal design of electrolyte and cathode materials. In this regard, optimizing electrode design and hybrid electrolyte transport properties is a straightforward approach to increase the cell energy density. For this purpose, numerical modeling has been previously applied to understand the electrochemical system when defining the best electrode and electrolyte design. The operation of a lithium ion battery (LIB) follows porous electrode theory and electrochemical reaction thermodynamics and Newman at col. developed the governing equations138 that later the community used for electrode design improvement purposes. For instance, LiFePO4 and nickel rich layered material LiNi1-x-y Mn xCoy O2 (NMC) thick electrodes were optimized by a combined experimental and simulation approach7 .5 LiNi0.8Co0.15 Al0.05 O2 (NCA)/graphite cell stack energy density was improved by a mathematical model.1 Furthermore, the influence of the negative electrode design (in terms of porosity and electrode thickness) was studied under Newman continuum model12 . The main aim in this work is to provide in-depth understanding of the cell performance and design improvement of the current status of the hybrid electrolyte technology through a novel approach relying on non-dimensional parameters. This approach arises as an appropriate tool to study the electrode performance since it brings the opportunity to identify the limiting factos in the battery performance by analyzing a somewhat reduced number of dimensionless parameters, which are obtained by condensating the huge number of physical, dimensional parameters involved in the description of the electrochemical phenomena taking place in the cell. Here, a parametric study is developed in order to identify the limiting mechanisms in each region of the parametric space of different Hybrid Electrolyte Batteries. For this purpose, battery consisting of porous cathodes (i.e NMC622), hybrid electrolyte and a lithium metal anode is examined and investigation of a much larger set of operation conditions of hybrid electrolyte based battery performance is also performed. By analyzing the resulting dimensionless parameters, the main physical phenomena that limit battery performance are identified (and rough estimates of voltage drops associated with each transport mechanism are obtained). Our resulting outcomes can be used as quantitative guidelines in the development and design of hybrid electrolyte batteries.