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

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-MnO(2 )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. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

The interfacial modification of layered materials can achieve high energy storage by allowing the occurrence of intercalation pseudocapacitance. The Bi2Se3-MnO2 nanotube composite shows excellent electrochemical performance in terms of high specific capacitance, capacitance retention, and energy density.