Thickness-Controllable Electrode of Lithium Titanium Oxide Nanowire Sheets with Multiple Stacked Morphology for Ultrahigh Areal Capacity and Stability of Lithium-Ion Batteries

Nowadays, thickness optimization of an electrode is considered an effective approach to achieve a high energy density or high areal capacity of Li-ion batteries. In this paper, we report a simple electrospinning technique to develop free-standing sheet bundles of lithium titanium oxide (LTO) nanowires with a readily controlled thickness of electrodes. The LTO nanowire sheet bundles (LNSBs) can show a very high areal capacity as an anode due to its microscale layer-by-layer configuration in which the nanoscale LTO nanowires are networked in each microscale layer. Such unique structures with interspaces formed between the multiple stacked sheet layers should promote electrolytes to efficiently penetrate through the thick electrode layer. Nanoscale wire assemblies can also increase the transfer rates of ions and electrons during the lithiation/delithiation processes. Consequently, the fabricated LNSB electrode delivers an ultrahigh areal capacity of up to ca. 14.2 mA h cm^–2 for the first cycle and ca. 6.5 mA h cm^–2 for the 500th cycle at 0.2C rate current density, which is a much larger areal capacity than the commercial graphite anode (ca. 3.5 mA h cm^–2). Such a high areal discharge capacity on a novel free-standing electrode design could provide an idea for advanced energy storage applications.