Preparation of FeSe₂/Ti₃C₂T_x Composites with Sodium Storage Properties

Selenides have a higher reversible capacity and a suitable working potential. However, their large volume change during cycling and low conductivity restrict their practical applications. In this paper, FeSe₂/Ti₃C₂T_x composites were synthesized as anode materials for sodium-ion batteries by a simple hydrothermal method. Fe²⁺ were firstly coordinated with ethylene diamine tetraacetie acid to form chelates, and then FeSe₂/Ti₃C₂T_x composites were synthesized via the electrostatic interaction between Ti₃C₂T_x and Fe²⁺ chelates after the hydrothermal reaction. FeSe₂/Ti₃C₂T_x has an open ‘flower petal’ structure, and Ti₃C₂T_x in the composite provides an intense conductive network for the material and relieves volume expansion. According to the results of the electrochemical test, Ti₃C₂T_x electrode has a capacity of 455 mA·h/g after 150 cycles at 0.5 A/g, while the capacity of FeSe₂ electrode at the same current density is only 335 mA·h/g after 100 cycles, and the capacity decays rapidly in the subsequent cycles. It is indicated that FeSe₂/Ti₃C₂T_x electrode has superior electrochemical sodium storage performance and cycling stability.