E-Mobility Engineering 019 | In conversation: Stephen Lambert l WAE EVR l Battery case materials focus l Quality control insight l Clipper Automotive Clipper Cab digest l Optimising battery chemistries insight l Powertrain testing focus

59 May/June 2023 | E-Mobility Engineering low activation energy. The researchers say the large-scale synthesis method, exceptionally high lithium storage characteristics, and exceptional SSE application of the layered SiS 2 make it highly suitable for various applications. “Researchers have struggled to address the elevated vapour pressure of sulphur, which required using expensive rawmaterials or introducing special processes,” says Dr Ha. “What we have achieved will contribute to producing SiS 2 for solid- state electrolytes cheaper and easier.” The team also used SiS 2 as an anode active material for liquid electrolyte- based lithium sulphur batteries, and identified the destruction and recovery of layered structures during charging and discharging for the first time. KERI is preparing a patent application for this technology. Another project, called SOLBAT, in the UK, is developing an understanding of themechanisms behind the premature short-circuiting and failure of solid- state batteries – a crucial step towards avoiding such events and realising the commercial potential of this technology. For the anode, the project will investigate the use of lithiummetal alloys, the nature of the anode/electrolyte interface and the use of lithium-less solid-state batteries as ways to increase critical current densities, improve cycling performance, reducemanufacturing costs and prevent cell failure by managing dendrite growth and void formation. For the cathode, the researchers are looking at polymers that can be used as a coating between the solid electrolyte and cathode active particles to minimise swelling and reduce cell operating pressures. Controlling the microstructure and mechanical properties of the solid electrolyte separator can minimise the growth of the dendrites that can cause short-circuits and reduce the thickness of the separator. Layered anodes Researchers from the Pohang University of Science and Technology (Postech) and Sogang University, in South Korea, have developed a functional polymeric binder for a stable, high-capacity anode material that could increase current EV ranges by a factor of at least 10. They produced it by replacing graphite with a silicon anode combined with a layered charged polymer binder to lithiation/delithiation capacity, of 1610/1363 mAh/g; a high initial coulombic efficiency, of 84.7%; extremely high cycling stability after 800 cycles; and a high rate capability. Furthermore, SiS 2 is incorporated into a lithium-argyrodite solid-state electrolyte (SSE) used in ASSBs, resulting in noteworthy air/moisture stability and high ionic conductivity with Deep insight | Optimising battery materials A charged polymer binding layer can boost solid-state battery performance (Courtesy of Postech) The morphology of silicon disulphide is key to building solid-state batteries (Courtesy of KERI)