Novel NASICON-type Mn0.5Ti2(PO4)3@F-doped carbon composite with high electrochemical performance as anode materials for potassium-ion batteries

Mn 0.5 Ti 2 (PO 4 ) 3 with a NASICON structural is used as an anode material in potassium-ion batteries due to its abundance of vacancies that can hold potassium ions . This characteristic not only contributes to its excellent stability but also results in a high specific capacity. However, the poor electrical conductivity of the polyanionic type structure limits the material's ability to fully utilize its capacity. In this paper, the conductivity and electrochemical stability of the Mn 0.5 Ti 2 (PO 4 ) 3 anode material are enhanced through composite formation with an F-doped carbon layer. The introduction of F into the carbon matrix creates a large number of vacancy defects and F active sites. The vacancies enhance the transport of potassium ions on the Mn 0.5 Ti 2 (PO 4 ) 3 material's surface, while the active sites exhibit strong electronegativity , improving the absorption of potassium ions. Therefore, the diffusion impedance of potassium ions is significantly reduced, leading to an increased diffusion rate of potassium ions. Attributing to the improved reaction kinetics, the Mn 0.5 Ti 2 (PO 4 ) 3 @F-doped carbon composite demonstrates a high specific capacity of 86 mA h g −1 at 10,000 mA g −1 when used as the anode for potassium-ion batteries. Even more, the specific capacity remains a capacity of 136 mA g −1 after 3000 cycles at 1000 mA h g −1 . This study enhances our comprehension of material design by investigating the alteration of carbon matrix to promote the electrochemical characteristics of materials.