Polydopamine@carbon nanotubes composite for sodium-ion-based dual-ion-batteries with high reversible capacity
Dual-ion battery has attracted widespread attention due to its high energy density,high safety,and low cost. However,limited by the large ionic radius of anions,finding cathode materials with stable structures has become the key to promoting the development of dual-ion batteries. To address the issues of limited anion storage capacity and short battery cycle life associated with traditional cathode materials,a sodium-based dual-ion battery cathode (named PDA@CNTs) was prepared by uniformly dispersing an appropriate amount of carbon nanotubes in deionized water,followed by adding an appropriate amount of dopamine to construct a polydopamine coating layer on the surface of the carbon nanotubes. The results showed that the carbon nanotubes improved the conductivity of the composite material,thereby enhancing its rate performance,and also provided a three-dimensional carbon skeleton for the in-situ polymerization of dopamine,exposing more active sites and achieving a high reversible capacity. The half-cell assembled with PDA@CNTs as the cathode and metallic sodium as the anode exhibited excellent electrochemical performance,with a reversible capacity of 108.1 mA·h/g and a capacity retention rate of 81.5％ after 50 cycles at a current density of 0.1 A/g. Compared with pure carbon nanotube materials,a significant optimization effect was achieved. This method increased the conductivity and active sites of the material,further improving the reversible capacity and rate performance of the cathode material,providing good guidance for the commercial application of dual-ion batteries.
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