Silicon anodes in solid-state batteries can swell by up to 300% during charging, cracking the electrode and breaking electrical contact. This swelling is the core problem the research tackles. Silicon offers far higher charge capacity than current lithium anodes, making it a promising material for next-generation batteries in electric vehicles. But its expansion during use creates internal mechanical stresses that cause delamination and loss of performance. While researchers have tried various fixes, using laser patterning to create controlled porosity and surface textures in silicon anodes remains largely unexplored. The PhD project will use a fibre laser to engineer the surface of silicon materials, increasing porosity and improving resistance to mechanical stress. The goal is to prevent the structural failures that currently block silicon from industrial battery production. If successful, the work could enable cheaper, higher-energy solid-state batteries for electric vehicles and grid storage. The research also includes an environmental assessment of the laser processing technique itself, measuring energy consumption and waste generation. This is applied engineering research with a clear practical target: making a promising but problematic material work reliably at scale.
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The growing expansion of renewable energy sources is driving an increased demand for energy storage systems that are both affordable and efficient. Among the various options, solid-state batteries (SSBs) stand out as one of the most promising technologies, particularly with ongoing research into new materials and advanced electrode architecture. Silicon, as a new-generation electrode material for SSBs, has become a key focus of recent research. This is especially pertinent considering the surging prevalence of electric vehicles in the transportation sector, necessitating a boost in the production capacity of cost-effective, high-power, and high-energy SSBs. In recent times, the most significant advancements have predominantly occurred in the realm of lithium-metal-oxide cathodes, while lithium anodes in SSBs have remained largely unchanged. Silicon, with its ability to provide a high charge capacity as the active material (AM) in anodes of all-solid-state batteries (ASSBs), has long been considered a promising medium for anodes. However, it may expand by up to 300% during charging, causing fluctuations, leading to internal mechanical stresses within the composite electrode, resulting in issues such as loss of electrical contact and delamination, thereby impeding its seamless integration into industrial battery production. While numerous researchers are exploring various promising approaches to facilitate the incorporation of silicon alloys in electrodes, the potential implementation of additional porosity and functionalisation of surface textures through laser patterning remains an under-researched area. There is growing evidence in literature that, for example nanowire geometry in silicon anodes allows less swelling compared to spherical nanoparticles [1], therefore there is a need not only to functionalise the geometry of the silicon nanowire anode technology but also to produce a basic understanding of the geometrical/topographical effect of the nanofeatures on the battery performance. Laser-based processing could offer the chance, for the first time, to solve issues of volume expansion of the anode when loaded with lithium ions and the resulting material fracture that can happen when an anode expands and contracts. The aim of this PhD is to develop novel laser processing strategies (texturing and laser surface engineering) using the 70 W Innolas MMS single mode SPI fibre laser (1060 nm wavelength) in the High-Power Laser Lab (Wolfson) with the following objectives: Increase the porosity of Silicon-materials by functionalising its surface properties. Improve resistance to mechanical stresses thereby avoiding delamination. Ultimately functionalise the electrochemical performance of batteries. This will be done using various techniques used in current battery research such as: Battery cycling evaluation, Electrochemical impedance spectroscopy (EIS) and Galvanostatic intermittent titration technique (GITT) [2]. Assessment of environmental impact of the developed technique. This will include energy consumption and waste generation analysis. References [1] https://doi.org/10.1002/ente.202400206; [2] https://doi.org/10.1007/s10008-023-05670-z
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