Structural Batteries for Aeronautic Applications—State of the Art, Research Gaps and Technology Development Needs

Radical innovations for all aircraft systems and subsystems are needed for realizing future carbon-neutral aircraft, with hybrid-electric aircraft due to be delivered after 2035, initially in the regional aircraft segment of the industry. Electrical energy storage is one key element here, demanding safe, energy-dense, lightweight technologies. Combining load-bearing with energy storage capabilities to create multifunctional structural batteries is a promising way to minimize the detrimental impact of battery weight on the aircraft. However, despite the various concepts developed in recent years, their viability has been demonstrated mostly at the material or coupon level, leaving many open questions concerning their applicability to structural elements of a relevant size for implementation into the airframe. This review aims at providing an overview of recent approaches for structural batteries, assessing their multifunctional performance, and identifying gaps in technology development toward their introduction for commercial aeronautic applications. The main areas where substantial progress needs to be achieved are materials, for better energy storage capabilities; structural integration and aircraft design, for optimizing the mechanical-electrical performance and lifetime; aeronautically compatible manufacturing techniques; and the testing and monitoring of multifunctional structures. Finally, structural batteries will introduce novel aspects to the certification framework

Rational Optimization of Cathode Composites for Sulfide-Based All-Solid-State Batteries

All-solid-state lithium-ion batteries with argyrodite solid electrolytes have been developed to attain high conductivities of 10−3 S cm−1 in studies aiming at fast ionic conductivity of electrolytes. However, no matter how high the ionic conductivity of the electrolyte, the design of the cathode composite is often the bottleneck for high performance. Thus, optimization of the composite cathode formulation is of utmost importance. Unfortunately, many reports limit their studies to only a few parameters of the whole electrode formulation. In addition, different measurement setups and testing conditions employed for all-solid-state batteries make a comparison of results from mutually independent studies quite difficult. Therefore, a detailed investigation on different key parameters for preparation of cathodes employed in all-solid-state batteries is presented here. Employing a rational approach for optimization of composite cathodes using solid sulfide electrolytes elucidated the influence of different parameters on the cycling performance. First, powder electrodes made without binders are investigated to optimize several parameters, including the active materials’ particle morphology, the nature and amount of the conductive additive, the particle size of the solid electrolyte, as well as the active material-to-solid electrolyte ratio. Finally, cast electrodes are examined to determine the influence of a binder on cycling performance

CleanSky2 SOLIFLY - Developing structural batteries towards aeronautic application

Radical innovations for all aircraft systems and subsystems are needed for realizing future carbon neutral aircraft, with Hybrid Electric Aircraft (HEA) to be delivered after 2035, at first in the regional aircraft segment. Electrical energy storage is one key element here, demanding safe, energy dense, lightweight technologies. Combining load bearing with energy storage capabilities is a promising way to minimise the detrimental impact of battery weight on the aircraft. However, despite the various concepts developed in recent years, the viability of this solution has been demonstrated at material or coupon level only, leaving many open questions concerning its effective applicability for structural elements of a size relevant to the effective implementation into the airframe. Within the CleanSky2 project SOLIFLY “Semi-SOlid-state LI-ion Batteries FunctionalLY Integrated in Composite Structures for Next Generation Hybrid Electric Airliners” (2021-2023) the AIT Austrian Institute of Technology, the aeronautics research centers ONERA and CIRA, the Universities of Vienna and Naples, and the SME CUSTOMCELLS Itzehoe, will be conducting research to develop further structural batteries towards aeronautic applications. Based on a non-conventional semi-solid-state formulation suitable for Li-ion structural batteries, two different scalable battery cell concepts are to be developed further and combined: on the one hand, so-called Coated Carbon Fibres (CCF/carbon fibres coated with active material), which intrinsically store energy, and, on the other hand, thin battery cells that are installed into the carbon composite structure (Reinforced Multilayer Stack/RMS). Functional integration of the formulation will be optimized, first at the cell level and subsequently scaling up the cell concepts, on a representative aerospace-grade component, here a stiffened panel, to demonstrate the electrochemical and mechanical properties of the developed structural battery technology. A further aspect that SOLIFLY focuses on is to closely link technological development to the actual needs of the aviation industry. To ensure this, the expectations and specifications of the aircraft manufacturers are incorporated into the design process from the very beginning, taking into account airworthiness and production requirements. A technology roadmap and a technology readiness level scale-up strategy are project outcomes which ensure that the inherently scalable processes can actually be industrialized. The talk will present the concept of SOLIFLY, the progress achieved in the first phase of the project including the outcome of a first industrial workshop

Assessing LiF as coating material for Li metal electrodes

International audienc

Optimizing Current Collector Interfaces for Efficient "Anode-Free" Lithium Metal Batteries

Current lithium (Li)-metal anodes are not sustainable for the mass production of future energy storage devices because they are inherently unsafe, expensive, and environmentally unfriendly. The anode-free concept, in which a current collector (CC) is directly used as the host to plate Li-metal, by using only the Li content coming from the positive electrode, could unlock the development of highly energy-dense and low-cost rechargeable batteries. Unfortunately, dead Li-metal forms during cycling, leading to a progressive and fast capacity loss. Therefore, the optimization of the CC/electrolyte interface and modifications of CC designs are key to producing highly efficient anode-free batteries with liquid and solid-state electrolytes. Lithiophilicity and electronic conductivity must be tuned to optimize the plating process of Li-metal. This review summarizes the recent progress and key findings in the CC design (e.g. 3D structures) and its interaction with electrolytes.Anode-free Li-metal batteries (AFLMBs) are a promising candidate for future high-energy density batteries, however, besides many advantages (safety and low cost), they still face challenges in terms of poor cycling life. This work discusses the challenges, current status, and important discoveries in optimizing the current collector as the host for Li-metal plating, since its critical role for achieving superior electrochemical performance