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Introduction to Nanostructured Multifunctional Materials
Published in Esteban A. Franceschini, Nanostructured Multifunctional Materials Synthesis, Characterization, Applications and Computational Simulation, 2021
In the particular case of UAV, the factors that affect flight efficiency are; the weight stored battery energy and the battery efficiency factor. Equation (18) (Thomas et al. 2002) shows how these parameters are related. It can be seen that the decrease in the aircraft weight increases flight time by 1.5 times, while the increase in battery capacity increases the autonomy by a factor of one So, for the development of this type of aircraft, weight reduction of both, the aircraft and the battery, is a priority. However, there is an alternative that implies a greater degree of integration which could be much more efficient to increase the flight time: Combining the battery with the structural parts using MFMS. ΔtEtE=1Δ(EBηB)EBηB−1.5Δ(WS+ΔWB)WB+WB where tE is the flight endurance time, EB is the nominal stored energy in the battery, ηB represents the battery efficiency factor which explains the influence of the current extraction rate, temperature, etc., on the amount of energy extracted, Ws is the aircraft weight and WB is the battery weight. Although there are numerous examples in the literature on the integration of batteries and capacitors with structural functions (Chan et al. 2018, Shi et al. 2016), one of great interest is that presented by Moyer et al. (2020). They design ad-hoc a structural battery for a 1U Cube Sat reducing considerably the weight of the system, due to the refunctionalization of part of the lithium-ion battery packs which occupy a significant volume in these systems. Specifically, in the case of four panels of structural batteries assembled in the 1U CubeSat, each with an energy density of 35 Wh/kg, it stores total energy of — 10 Wh, which decreases the total required mass of external batteries in — 30% in this configuration and creates free volume in the CubeSat chassis, approaching the operational requirements of NASA. This system was designed and tested with favourable results.
Finite element analysis and experimental investigation on the mechanical behaviours of multifunctional sandwich structures embedded with batteries
Published in Advanced Composite Materials, 2022
Research on multifunctional energy storage composite structures (sometimes known as structural batteries) aiming to improve energy storage and space efficiency without sacrificing load-bearing capacity of structures has recently attracted researcher’s attention. Attar et al. and Pattarakunnan et al. [3,4] inserted pouch lithium-ion batteries into carbon fibre composite laminates. They found that the pouch cell battery insertion caused an adverse effect on the mechanical properties which could be attributed to discontinuities in the carbon fibres, geometric stress concentration created by the pouch cell, lower mechanical properties of the pouch cell compared to the carbon fibre composite laminate, and poor load transfer at pouch cell-composite laminate interface. Ladpli et al. [5] reported the design, fabrication processes, and experimental mechano-electrical characterization of a structural battery panel made by encapsulating lithium-ion battery materials inside carbon-fibre composites and using interlocking polymer rivets to stabilize the electrode layer stack. Their experiments demonstrated that the structural battery had a comparable electrochemical behaviour to baseline, higher mechanical rigidity than pouch cells, and negligible capacity fading after 1000 bending cycles at 80% design load. Instead of using the interlocking polymer rivets, Moyer et al. [6,7] used a traditional composite layup method (layup process) to combine lithium-ion battery active materials with carbon fibre weave materials. In their work, epoxy resin was used as a packaging medium for the battery whereas the carbon fibres were used as both a structurally reinforcing layer and conductive current collector. Javaid et al. [8] used resin infusion method with flexible tooling to fabricate structural batteries containing woven carbon fabric anode, lithium cobalt oxide/graphene nanoplatelets coated aluminum cathode, filter paper separator and cross-linked polymer electrolyte. Their experimental results showed that the compressive properties of the structural batteries would decrease with increasing concentrations of electrolyte salt in cross-linked epoxy resin (the ionic conductivity). Snyder et al. [9] who pioneered the development of multifunctional laminated structural batteries used lithium iron phosphate cathode and a vinyl ester random copolymer as polymer electrolytes. Johannisson et al. [10] proposed a model for multifunctional performance of a structural battery and presented various case-studies including interior panel in aircraft, electric vehicle roof, hull of electric ferry, and laptop computer chassis. The model could be used to improve the design of the structural battery, i.e. to achieve mass saving compared to the monofunctional systems (composite laminates and lithium-ion batteries).