Interface Polarization Effects Enhancing Mn<sub>2</sub>O<sub>3</sub>@TiO<sub>2</sub>@MXene Heterostructures for Aqueous Magnesium Ion Capacitors: Guided Charge Distribution and Transportation via Built‐in Electric Fields
Mudi Li, Yaxi Ding, Siwen Zhang, Ying Sun, Minghui Liu, Jianwei Zhao, Bosi Yin, Tianyi Ma
Abstract
The electrochemical performances of aqueous magnesium ion energy storage devices rely on the transmission capacity of magnesium ions (Mg 2+ ) at the electrode/electrolyte interface. However, the diffusion of Mg 2+ is hindered by the strong electrostatic attraction of doubly charged magnesium cations. Herein, novel Mn 2 O 3 @TiO 2 @MXene three‐phase heterostructures with rich phase boundaries and synergistic effects is successfully designed. As expected, the mesoporous Mn 2 O 3 /TiO 2 @MXene can deliver a relatively high specific capacity of 241.5 mAh g −1 at 0.1 A g −1 . Moreover, the energy density of the device using mesoporous Mn 2 O 3 @TiO 2 @MXene as cathode can reach 146.62 Wh kg −1 . The unique construction of extensive interfaces between different phases creates a polarization effect. This polarization effect leads to intrinsic electric fields that guide charge distribution and promote fast migration of Mg 2+ ions. Additionally, the in‐situ growth of TiO 2 nanoparticles derived from MXene on Mn 2 O 3 helps mitigate the volume expansion of host material, resulting in enhanced cycle stability. By strategically implementing the interface polarization effect and carefully engineering the heterostructure interfaces, we demonstrate a promising electrode synthesis approach with potential commercial viability and robust performance. This research aims to advance the field of materials science by exploring interface engineering and the multifunctional applications of MXene‐related materials.