Intercalation pseudocapacitance in Bi2Se3−MnO2 nanotube composite for high electrochemical energy storage

Abstract

Layered materials exhibit exclusive electrochemical properties centered on interlayer spaces. However, slow kinetics and poor cycling stability restrict overall performance. A possible solution to deliver high energy storage is by interfacial modification of layered materials, which can structurally allow the occurrence of intercalation pseudocapacitance at redox-capacitance timescale. In this work, MnO2 has been intercalated in-situ in layered Bi2Se3 for the first time to give Bi2Se3−MnO2 nanotube composite. Structural and morphological characterizations have been conducted elaborately by several experimental and theoretical studies. Electrokinetic measurements reveal a dominant capacitive mechanism of 69% at 60 mV s − 1. Ex-situ XRD analysis after electrochemical charge-discharge cycles show reversible shifts in c-axis containing Bi2Se3 (015) plane, which confirms intercalation pseudocapacitance. The nanocomposite demonstrates high specific capacitance (438 F g − 1 at 1 A g − 1 in a three-electrode system) in a wide potential window of 2 V. Moreover, a symmetric two-electrode system for Bi2Se3−MnO2 exhibits a high energy density of 62 Wh kg−1 and a power density of 2.7 kW kg−1 at 1 A g − 1 and 10 A g − 1, respectively, along with capacitance retention of 86% after 2000 cycles. The study gives promising direction to design integrated high energy and power density intercalation pseudocapacitive materials. © 2020