Synthesis of Spherical Mesoporous TiO2 for High-Performance Battery-Supercapacitor Hybrid Devices

Abstract

Hybrid supercapacitors, integrated system of battery and supercapacitor, have been increasingly studied due to its excellent energy density as well as high power density, with long cycle life. However, it is suffer from kinetic imbalance between sluggish faradaic anode based on lithium ion intercalation and rapid non-faradaic capacitive cathode. One of the solutions of the imbalance problem is take high-power anode materials which can be possible fast charge/discharge. Another solution is nanostructuring electrode resulting in higher capacity and rate capability. Herein, we choose high power anode material, titanium dioxide (TiO2) and synthesized mesoporous TiO2 using facile one-pot self-assembly. The m-TiO2 electrode exhibit high capacity and rate performance derived from carbon-coated mesostructured; reversible capacity of ~198 mA h g-1 at 0.05 A g-1 within a potential range 1.0-3.0 V (vs. Li/Li+). The lithium-ion hybrid supercapacitor system fabricated using mesoporous TiO2 anode and activated carbon cathode perform high energy density and power density (63 W h kg-1, and 4,044 W kg-1) within a potential window form 0-3.0V. On the other hand, mesoporous structured samples have some challenge related to volume occupation. Due to its huge surface area and pore volume, mesoporous structured electrode occupied large space, which interrupt commercialization. To mitigate this problem, morphology controlled particle was synthesized through simple method. Therefore, spherical mesoporous TiO2 performed improved volumetric capacity with excellent rate capability (228 mA h cm-3 at 0.05 A g-1 and 92 mA h cm-3 at 5 A g-1). Volumetric energy and power density of lithium-ion hybrid supercapacitor using spherical TiO2 are 36 W h L-1 and 1269 W L-1. In this works, we suggest the direction of lithium-ion hybrid supercapacitors for commercialization.