41 Acknowledgements The author would like to thank JJ Kim and Johannes Eschenauer at Hitachi Hightech for their help with researching this article. E-Mobility Engineering | September/October 2023 forms molybdenum oxide within the MXene’s structure. To tackle this problem, the researchers used infrared laser pulses to create small ‘nanodots’ of molybdenum carbide within the MXene, a process called laser scribing. The nanodots, roughly 10 nm wide, were connected to the MXene’s layers by carbon materials. This offers several benefits. First, the nanodots provide additional storage capacity for lithium and speed up the charging-discharging process. The laser treatment has also been shown to reduce the oxygen content in the layer, helping to prevent the formation of problematic molybdenum oxide. Finally, strong connections between the nanodots and the layers improve the MXene’s conductivity and stabilise its structure during charging and discharging. This provides a cost-effective and fast way to tune battery performance. An anode constructed from the laser-scribed material was tested in a lithium-ion battery over 1000 chargedischarge cycles. With the nanodots in place, the material had a fourfold higher electrical storage capacity than the original MXene, at 340 mAh/g versus 83 mAh/g, and an improved cycling stability with a capacity retention of 106.2% versus 80.6% for pristine over 1000 cycles. This laser scribing could be applied as a general strategy to improve the properties of other MXenes for a new generation of rechargeable batteries that use cheaper and more abundant metals than lithium such as sodium and potassium ions. Digital twin analysis Digital twin technology can be used to evaluate battery materials’ characteristics using computational models, minimising the need for complex equipment and speeding up analysis. A battery electrode degradation diagnosis technology has been developed in Korea that uses a particlelevel multi-physics model of high-nickel active materials to identify the root causes of performance degradation in battery particles. It offers optimal particle designs through a more detailed analysis of their electrochemical and mechanical properties. The model accurately diagnoses the internal structure by replicating the intricate particle arrangement found in actual batteries in a virtual environment. The model isolates and evaluates the numerous micrometre-sized particles in the electrode, effectively eliminating external factors that have an impact on battery performance. The model reveals the actual characteristics of the active materials responsible for generating electrical energy, enabling highly precise measurements and ways to develop optimal particle designs. The structures in digital twins closely resemble real particles and accurately predict volume changes during battery operation. The technology not only enables the diagnosis of electrode particle degradation but also offers opportunities for optimising designs to overcome such challenges. Conclusion There are many techniques for analysing the surface of battery materials, from X-ray spectrometry to laser diffraction. But new techniques, from in-situ XPS analysis to cryo-EM and new ways to measure the shape of nanoparticles, are improving the accuracy of the analysis and the understanding of the way the layers interact with each other in a battery cell over time. All this enhanced data is also helping to improve the computational models used in digital twins of the battery cells. The improved accuracy of the twins is helping to develop new battery cell designs without having to use expensive analysis equipment all the time. Developing new designs and then testing the materials is leading to longer lifetimes and higher energy density in the cells to boost the range and performance of e-mobility platforms. A rendering of the rhombic dodecahedron shape that lithium atoms formed on a surface with the researchers’ technique for avoiding corrosion (top), with four illustrations (middle and bottom rows) showing the irregular shapes that appeared in conditions where corrosion formed (Courtesy of UCLA)
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