Titanium doped niobium oxide for stable pseudocapacitive lithium ion storage and its application in 3 v non-aqueous supercapacitors

Developing high energy density supercapacitors is of great importance to the transportation, consumer electronics and micro-grid energy storage sectors. In this contribution, we introduce a titanium doping strategy to enhance the electrochemical performance of orthorhombic phase niobium oxide (T-Nb₂O₅). The Ti doping is able to provide an additional redox reaction and reduce the charge transfer resistance during the electrochemical reaction. As a result, Ti doped T-Nb₂O₅ shows a pseudocapacitive Li⁺ storage capacity of 204.3 mA h g^-1 and a capacity retention of 88.8% after 1000 cycles at 5C rate. Moreover, a non-aqueous supercapacitor prototype based on Ti doped T-Nb₂O₅ and polyaniline-single wall carbon nanotubes is fabricated. The 3 V prototype supercapacitor achieves an enhanced energy density of 110.3 Wh kg^-1 at 150 W kg^-1.