Lawrence Berkeley National Laboratory

Baseline Si electrodes were developed and characterized based on Si nanomaterials. Silicon (Si) with a designed nanostructure has attracted much attention as potential anode materials for lithium-ion batteries due to its high gravimetric specific capacity. Because of a resulted poor tap density of Si from the electrode while using nano-sized Si and also from including other additives like conductive carbon and binder, it is difficult to maintain a high loading of active materials at the anode side in lithium-ion batteries. In this report, we aim to investigate how the thickness of Si-based electrode influences the cycling performance, rate performance and impedance. We also discuss the variation of gravimetric, area and volumetric capacity along with increasing of electrode thickness. It is found that with a thinner electrode of 7 μm the volumetric capacity could reach up to 920 mAh cm-3 but a poor area capacity of 0.7 mAh cm-2, while a thicker one of 33 μm enables to provide a high area capacity up to 1.5 mAh cm-2 and gives a volumetric capacity less than 500 mAh cm-3. A cell operated under 0 °C shows a gravimetric capacity of 2000 mAh g-1 after 60 cycles.