by Isık İpek Avcı Yayla (ENW)
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by Isık İpek Avcı Yayla (ENW)
October 21, 2024
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Lithium-ion batteries (LIBs) are widely used in portable electronic devices due to their high energy density, excellent performance, and long cycle life. Silicon (Si) has become a highly favored material for enhancing the capacity of the negative electrodes in these batteries. This is largely due to silicon’s impressive theoretical capacity of 3500 mAh/g, low discharge potential (approximately 0.5 V against Li/Li+), and ability to store up to 4.4 lithium atoms per silicon atom.
Despite these advantages, the use of silicon in lithium-ion batteries faces significant challenges. The most critical of these is the excessive volumetric expansion—up to 300%—that silicon undergoes during the charge and discharge process (lithium intercalation and deintercalation). This dramatic expansion leads to instability in the solid-electrolyte interface (SEI) and causes the silicon atoms to pulverise, which results in a rapid decline in battery capacity over time.
To mitigate this issue, polymer binders have been introduced to improve the electrode performance of silicon-lithium alloys. These binders allow the silicon particles to expand and contract within a buffer matrix, helping to maintain the structural integrity of the electrode. However, further advancements have been made by incorporating self-healing polymers (SHP) as binders, which have shown to significantly reduce the pulverisation of silicon nanoparticles, extending the life and capacity of the batteries.
The PHOENIX project has focused on improving the performance of these self-healing polymers. Specifically, they have developed an SHP with long linear chains and hydroxyl functional groups, synthesised through a process called free radical polymerisation. By embedding Fe₃O₄ nanoparticles into the copolymer, the resulting material can be magnetically triggered, allowing for controlled and enhanced self-healing capabilities.
In studies conducted by the PHOENIX project, it has been demonstrated that this magnetically triggered self-healing polymer not only prevents the degradation of the silicon anode but also contributes to a longer battery life cycle and increased capacity. This innovation offers a promising step forward in the development of next-generation lithium-ion batteries, with the potential to significantly improve both performance and longevity.