Unveiling the role of atmospheric plasma treatment in boosting MXene-based heterostructure for supercapattery application

Abstract

The increasing demand for advanced energy storage technologies has driven the need for a single energy storage device (ESD) capable of delivering high energy density, high power density, and long-term cyclic stability. However, existing ESDs are unable to achieve these critical attributes simultaneously. To overcome the existing limitations, a hybrid device known as a supercapattery was developed by integrating a battery-type electrode with a capacitive-type electrode. In this study, carbon electrode as capacitive electrode was employed to ensure high power delivery, while a novel MXene-based heterostructure was designed as a battery type electrode material to enhance the energy density. This heterostructure was synthesized by integrating a zirconium oxide@zirconium carbide MXene (MX) with a zinc‑nickel carbonate hydroxide hydrate (Zn-NiCHH) composite via a facile hydrothermal method. Subsequently, the material was subjected to atmospheric plasma jet treatment, resulting in a remarkable specific capacity/specific capacitance of 1423.80 Cg⁻¹/3046.21 Fg⁻¹ with an exceptional rate capability of 96 % at a high current density of 10 Ag⁻¹. This enhancement is attributed to improved surface chemistry, morphological modifications, and the introduction of diverse surface functionalities, which collectively enhance the electrical conductivity and surface wettability, facilitating rapid faradaic reactions. The assembled supercapattery demonstrated a significantly higher maximum energy density (45.83 Wh kg⁻¹) and competitive maximum power density (6680 W kg⁻¹), positioning it as a promising electrode material for next-generation ESDs. Furthermore, the device exhibited excellent cyclic stability, retaining 82 % of its capacity over 8000 continuous charge-discharge cycles.