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Silicon as a high energy material for lithium ion batteries

Published on 12 March 2020
Silicon (Si) is the most promising high-capacity candidate for the next generation anodes of lithium-ion batteries thanks to its theoretical capacity about 10 times higher than the capacity of the actual commercial anode material, graphite. However Si expands enormously when lithiating during battery charge, which causes pulverization, contact loss and continuous formation of unstable solid electrolyte interphase (SEI).

Si nanowires (SiNWs) withstand mechanical constraints due to lithiation/delithiation better than Si nanoparticles. In Si nanoparticles, lithiation/delithiation induces a large swelling/deswelling of the Si crystal. The particles crack under strain, offering new surface to make SEI at each cycle, reducing the available Li and Si quantity in the battery. Some particles lose electrical contact and stop cycling. These effects are reduced in SiNWs because of their long aspect ratio.