Vertically aligned polyaniline nano-array decorated on ultra-thin MXene nanosheets for high energy density supercapacitors

Abstract

Titanium carbide (Ti3C2), with the features of metallic conductivity and two-dimension (2D) structure, is considered as a promising material using in supercapacitors. In this work, a kind of Ti3C2-based nanocomposite with vertically-aligned polyaniline (PANI) nanoarrays was prepared by simple in-situ polymerization, where Ti3C2 served as a conductive substrate supporting the growth of PANI. Vertically aligned PANI nano-array may increase the surface area, provide considerable pseudocapacitance, and prevent the aggregation of Ti3C2 nanosheets. Owing to its hierarchical structure, the composite electrode gained significant advantage in increasing electrochemical active sites and accelerating electrolyte ions diffusion. The energy storage devices with high electrochemical performance and simple preparation methods has attracted much attention reached 536 F g−1 at the current density of 0.1 A g−1, and the composite had a good capacitance retention and cycle stability (86.2 % after 5000 cycles) at a high current density of 10 A g−1. In addition, the symmetric supercapacitor was assembled and displayed a high energy density (933.9 W kg−1) at the power density of 26.9 Wh kg−1. After 5000 charge-discharge cycles, the capacitance retention rate is 70.4 %. The experimental results indicated that the improved electrochemical performance of supercapacitor was closely related to the introduction of Ti3C2 and construction of the hierarchical structure. Furthermore, the preparation strategy of Ti3C2-PANI composite can be used to further produce other composites with similar regular structure and unique electrochemical performance.