Fabrication of versatile nanocomposite materials for advanced energy storage systems

Abstract

In general, the energy density capacity of the Li-S battery is exceptional, reaching a value of 2600 Wh kg-1, nearly five times higher than that of the lithium-ion battery. However, the application of this technology faces a lot of challenges because of the polysulfides shuttle effect and redox reaction that results in the kinetic capacity loss of the electrode material. In this current study, anatase phase TiO2 nanotubes with a size of approximately 18.3 nm were fabricated by the hydrothermal technique as a multifunctional additive in three different forms: TiO2 nanotubes, nickel oxide decorated TiO2 nanotubes (NiO/TiO2), and nickel metal-modified TiO2 nanotubes (Ni/TiO2). These materials were deposited onto carbon fibre paper to fabricate cathode materials. It should be noted that TiO2 has a high polarity nature and acts as a good adsorbent for polysulfides, but the material is characterized by poor electron conductivity and catalytic activity. After decoration with NiO nanoparticles, TiO2 can demonstrate improved ability for chemisorption and oxidation-reduction of polysulfides. Nickel metal nanoparticles decoration improves electronic conductivity and facilitates interfacial reaction. According to all analyzed cells, the one that contains Ni/TiO2 electrode provides a superior energy output with a specific capacity of 1285 mAh g-1 and after 100 cycles, obtained 1095 mAh g-1 at the sulfur load of 4 mg cm-2 under 0.2 C discharge rate. It was observed that the same cell maintains distinguished charge-discharge plateaus without polarization after 100 cycles. The minimum transfer resistance of 14Ω and maximum Li2S nucleation of 746 mAh g-1 have been achieved by using Ni/TiO2.