Preparation and Properties of P-Bi<sub>2</sub>Te<sub>3</sub>/MXene Superstructure-Based Anode for Potassium-Ion Battery

Abstract: With increasing global energy demand and stricter environmental protection requirements, energy storage technology has become a research hotspot in the global energy field. New types of energy storage devices continue to emerge owing to the continuous development of cost-effective energy storage technology. Among them, potassium-ion batteries have received widespread attention as a new type of alkali metal ion battery because of their high capacity and low cost and are considered one of the future development directions. However, the research on potassium-ion batteries is still in its infancy, with many challenges to overcome regarding practical applications. A key factor affecting the performance of potassium-ion batteries is the anode material, as it not only affects the manufacturing costs but also directly affects the power density and energy density of the battery. Traditional anode materials for lithium-ion batteries cannot meet the requirements of potassium-ion batteries. Therefore, developing high-performance anode materials suitable for potassium-ion batteries is an important research direction at present. The charge and discharge rate and cycling life of potassium-ion batteries also need further improvements. Currently, the low-rate performance, short cycle life, and unsatisfactory practical capacities limit their practical application and commercialization. However, the future of potassium-ion batteries remains promising. Upon resolving the aforementioned issues, potassium-ion batteries will have diverse application prospects, such as electric vehicles, energy storage stations, and smart grids, providing important support for solving energy problems. Therefore, the research and development of potassium-ion batteries are an important direction in the global energy field. Current research efforts are primarily focused on exploring novel anode materials with exceptional ratability and cyclability. In this regard, we synthesized a new type of anode material based on bismuth telluride (Bi2Te3) and experimentally studied its applicability in potassium-ion batteries. The performance of Bi2Te3 anode for potassium-ion batteries has been limited by its structural instability and slow electrochemical reaction kinetics. In this study, rod-like Bi2Te3 was grown on accordion-like MXene, followed by P-doping to obtain a high-performance P-Bi2Te3/MXene superstructure. This novel anode had abundant Te vacancies and good self-auto adjustable function, providing excellent cycling stability (323.1 mAh·g-1 after 200 cycles at 0.2 A·g-1) and outstanding rate capability (67.1 mAh·g-1 at 20 A·g-1). Kinetic analysis and ex situ characterization indicate that the superstructure exhibits superior pseudocapacitive properties, high electrical conductivity, favorable diffusion capability, and reversible insertion and conversion reaction mechanism.