ISSUE 011 Autumn 2021 Candela C-7 hydrofoil speedboat dossier l In conversation: Robert Hoevers l Battery recycling focus l Vehicle dynamics insight l ZeroAvia hydrogen-electric aircraft digest l Motor materials

Nanotech alloy ups HVpower Xtalic has used its nano-structured silver coating to provide more powerful connectors for high-voltage EVs (writes Nick Flaherty). Extending the safe operating temperature of connectors above the current limit of 170 C allows higher current and voltages to be used. That increases the efficiency of the powertrain and helps reduce charging times. The coating, produced using a process called LUNA developed at the Massachusetts Institute of Technology in the US, consists of 50 nm particles of a silver alloy. This is stable above 220 C, allowing higher current for fast charging, but also provides the hardness needed for reliable connectors. Traditional contact finishes such as metallic silver coatings rely on electrically derating connectors at higher temperatures to provide a safety margin, but that limits their performance. To tailor the properties of the silver alloy to meet the requirements of different powertrain electrical connections, Xtalic engineers have used the company’s Dynamic Nanostructure Control software and Rapid Alloy Design toolkits with EV OEM and Tier 1 designers. Controlling the grain size provides the ability to tailor metal properties and maintain those properties at higher temperatures – a major improvement over traditional silver and silver alloys. In high-power EV connectors, LUNA targets the transfer of more current at the higher maximum operating temperature of 220 C while maintaining safe operation. In EV charger contacts, LUNA has a low insertion force and improved wear, enabling a much thinner coating – at 25% thickness compared with traditional silver – for better durability and improved corrosion resistance. LUNA extends the thermal stability performance of contact physics beyond the maximum contact interface temperature of 170 C and the transient current-carrying capability limitations of traditional silver. The thermal stability provides low and stable resistance after heat ageing at 210 C for 4000 hours. LUNA is also twice as hard as traditional silver plating across temperatures from 23 to 200 C. The LUNA material is applied using a traditional electro-deposition process for connectors, and Xtalic provides the chemistry and process knowledge so that existing electroplating facilities can be used. CONNECTORS Comparison of the LUNA silver alloy for connectors versus a traditional coating Matrix aimed at seal and EMI issues MATERIALS Datwyler is developing a materials matrix for e-mobility applications that range from design and development to testing and industrialisation (writes Nick Flaherty). The Electrically and Thermally Conductive and Electromagnetic Interference Shielding Materials (ETEMI) project aims to enhance conventional elastomers, liquid silicon rubber and thermoplastics to address sealing and EMI issues in EVs at the same time. This is driving the development of a new class of electrically conductive sealing materials. Hybrid and battery EVs need sealing components with enhanced functionality, such as sensing seal integrity or keeping electrical charge locally in a battery gasket. One example is a seal in a battery pack produced with thermally conductive elastomer material. This is spurring the development of a matrix of materials where electrical and thermal conductivity and EMI shielding can be coupled and decoupled to suit a variety of applications, said Luana Lettieri, manager, materials development, at Datwyler. The choice of material would allow the thermal management of an EV battery to be managed in part by its sealing material, for example, while EMI shielding could be introduced via sealing technology to safeguard components such as sensors from environmental effects as well as EMI. Electrical conductivity for discharging static is also possible using the sealing materials. This would allow components such as metal conductors to be removed, reducing the weight of the platform. The ETEMI project is developing compounds using mixing equipment and specific mixing programmes to provide the conductivity in the materials. 6 Autumn 2021 | E-Mobility Engineering The Grid